Title:
Inserts and method and apparatus for embedding inserts in cast members
Kind Code:
A1


Abstract:
Method and apparatus for forming cast members having curved or flat walls. Steps are provided in the cast member by placing hollow plastic step inserts into holders provided along the inner core of a mold assembly or mounting inserts on reciprocating pins or mounting inserts to a marginal portion of the inner core. The cast material is then poured into the mold. The cast member, when set, is withdrawn from the mold assembly. In one embodiment, a holder portion of the step insert is broken away, leaving the step inserts embedded in the cast member to receive legs of manhole steps. The inserts are provided with flanges, preventing leakage of the cast material into the mold assembly. Similar seals are provided by other types of cylindrical-shaped inserts for use in wetcast and drycast fabrication methods. Mounting assemblies are also provided for holding inserts for embedment in planar walls.



Inventors:
Westhoff, James A. (Langhorne, PA, US)
Kelly, James A. (Upper Black Eddy, PA, US)
Application Number:
11/107252
Publication Date:
09/01/2005
Filing Date:
04/15/2005
Assignee:
Poly-Tec Products, Inc. (Tullytown, PA, US)
Primary Class:
International Classes:
B28B21/56; B28B23/00; E04B1/41; E04G15/06; E04G21/18; E06C9/04; (IPC1-7): B22D19/00; B22D33/04; E04B1/38; E04C5/00
View Patent Images:
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Primary Examiner:
ROBITAILLE, JOHN P
Attorney, Agent or Firm:
VOLPE AND KOENIG, P.C. (30 SOUTH 17TH STREET, 18th Floor, PHILADELPHIA, PA, 19103, US)
Claims:
1. An apparatus for producing cast members having step inserts embedded therein for receiving legs of a step, comprising; a mold assembly having inner and outer walls forming a hollow space defining a member to be cast; one of said inner and outer walls having at least one mounting opening; at least one insert member having a body portion and integral mounting portion inserted into said mounting opening for retaining the insert member on said mold assembly during a casting operation; at least a portion of said mounting portion breaking away from the body portion when said cast member is separated from the mold assembly; said main body portion being hollow and open at one end and having internal projections for force-fittingly receiving and holding one leg of the step member; and said body portion including a sealing flange covering the mounting opening to prevent cast material inserted into the mold assembly from seepage therethrough.

2. The insert of claim 1 wherein mounting means comprises a plurality of flexible hook-like members for gripping a marginal portion of said opening and cooperating with said flange to retain said insert member in said opening.

3. The insert of claim 1 wherein said housing is provided with a plurality of annular flanges integral with and extending radially outwardly from said housing and spaced along the housing for retaining the insert in place when embedded in a cast member.

4. The insert of claim 1 wherein said closed end has an annular flange integral with said housing and extending radially outward therefrom to seal an opening in a mold core preparatory to insertion of the insert into a cast material.

5. In combination, an insert and a reciprocatable pin assembly for receiving said insert for insertion into a casting material, said insert comprising: a hollow, substantially cylindrical-shaped, elongated housing having an open end and a closed end; one of said ends and having a flange lying in a plane diagonally aligned with a longitudinal axis of said housing; another one of said ends having a flange lying in a plane perpendicular to said longitudinal axis; said pin assembly having a first cylindrical-shaped portion of a first diameter; a second cylindrical-shaped portion of a second diameter less than said first diameter, one end of said second portion being integrally joined to one end of said first portion, forming an annular ledge at the juncture thereof; said ledge lying in a plane perpendicular to a longitudinal axis of said pin assembly; said pin assembly second portion being inserted into said insert through said open end with said open end resting on said ledge; said pin assembly having an integral projection arranged on said ledge and extending along said second portion toward a free end thereof; said insert having at least one slot extending inwardly from said open end for receiving said projection for aligning said insert on said pin assembly.

6. A method for producing in a mold assembly a cast member having openings for receiving the legs of a step and employing a pin assembly and insert comprising: (a) providing a pin assembly, said pin assembly having a first cylindrical-shaped portion of a first diameter; a second cylindrical-shaped portion of a second diameter less than said first diameter one end of said second portion being integrally joined to one end of said first portion, forming an annular ledge at the juncture thereof; said ledge lying in a plane perpendicular to individual axis of said pin assembly; said pin assembly having an integral projection arranged on said ledge and extending along said second portion toward a free end and thereof; (b) providing an insert having a hollow substantially cylindrical-shaped elongated housing having an open end and a closed end; one of said ends and having a flange lying in a plane diagonally aligned with a longitudinal axes of said housing another one of said ends having a flange lying in a plane perpendicular to said longitudinal axis; said insert having at least one slot extending inwardly from said open end for receiving said projection for aligning said insert on said pin assembly. (c) placing said insert on said pin assembly second portion by inserting said second portion through the open end of said insert; (d) sliding the insert onto said second portion until said open end engages said ledge; (e) orienting said insert on said pin assembly to align said insert so that said slot receives said projection; (f) projecting said pin assembly through an opening in said mold assembly and into casting material in said mold assembly; and (g) withdrawing said pin assembly from the casting material, whereby said insert remains properly positioned in said casting material.

7. An insert assembly adapted to be embedded in a cast member for force-fittingly receiving a leg portion of a step, said insert assembly being comprised of: first and second members adapted to be telescopingly mounted to one another; said first member comprising a hollow, substantially cylindrical-shaped elongated housing having first and second open ends and an integral annular flange intermediate said first and second ends, said flange being diagonally aligned to a longitudinal axis of said first member; said second member comprising a hollow, substantially cylindrical-shaped elongated housing having a first closed end and a second open end; said open end of said second member being telescopingly mounted upon one end of said first member, whereby the second member is force-fitted on said first member.

8. The insert assembly of claim 7 wherein said second member is provided with a plurality of outwardly extending integral flanges arranged at spaced intervals therealong to enhance embedment of the second member in a cast member.

9. The insert assembly of claim 7 wherein an interior surface of said second member has a portion thereof being provided with a plurality of annular projections extending radially inward; and each projection having tapering cross-section.

10. The insert assembly of claim 7 wherein said first member has a portion of reduced thickness adjacent said diagonally-aligned flange to facilitate breaking away of a portion of the first member from said second member.

11. The insert of claim 10 wherein said portion of reduced thickness is obtained by scoring the first member.

12. The insert assembly of claim 7 wherein said first member is provided with a plurality of outwardly directed annular flanges for gripping an interior surface of said second member, the surfaces of said flanges being inclined so that it requires less force to telescopingly mount the second member onto the first member than is required to pull the first and second members apart.

13. The insert assembly of claim 7 wherein an interior of said second member is provided with a helical annular flange for gripping an exterior surface of said first member, the surface of said helical flange being inclined so that it requires less force to telescopingly mount the second member onto the first member than is required to pull the first and second members apart, said helical annular flange also serving to form a snug press-fit with a leg of a step member insertable therein.

14. A method for embedding inserts in a cast member, said inserts being comprised of an assembly of first and second members adapted to be telescopingly mounted to one another; said first member being a hollow, substantially cylindrical-shaped elongated housing having first and second open ends and an integral annular flange intermediate said first and second ends, said flange being diagonally aligned to a longitudinal axis of said first member; said second member being a hollow, substantially cylindrical-shaped elongated housing having a first closed end and a second open end; said open end of said second member being capable of being telescopingly mounted upon one end of said first member, said method comprising the steps of: (a) providing a mold assembly including an annular-shaped core member having at least one opening and a tubular step tube joined to the core member and aligned with said opening and extending inwardly from a concave surface of said core member; (b) inserting one end of said first member into a convex surface side of said core member and into said step tube, whereby said first member is force-fitted in said step tube, said first member being pushed into said step tube by a distance sufficient to move said diagonally-aligned flange adjacent to a marginal portion of said core surrounding the opening in said core; and (c) telescopingly mounting said second member onto an end of said first member extending outwardly from the convex surface of said core, whereby said second member is force-fitted to said first member.

15. The method of claim 14 further comprising providing an annular-shaped area on said first member adjacent to said diagonally-aligned flange designed to enable the first member to easily break away from said second member when cast material, which is poured into the mold assembly, has set and the cast member is separated from said mold.

16. A method for embedding inserts in a cast member, said inserts being comprised of an assembly of first and second members adapted to be telescopingly mounted to one another; said first member being a hollow, substantially cylindrical-shaped elongated housing having first and second open ends and an integral annular flange intermediate said first and second ends, said flange being diagonally aligned to a longitudinal axis of said first member; said second member being a hollow, substantially cylindrical-shaped elongated housing having a first closed end and a second open end; said open end of said second member being adapted for being telescopingly mounted upon one end of said first member, said method comprising the steps of: (a) providing a mold assembly including an annular-shaped core member having a pair of openings and a pair of cylindrical step tubes joined to the core member and each being aligned with one of said openings and extending inwardly from a concave surface of said core members that the longitudinal axis of said step tubes are substantially parallel; (b) telescopingly mounting said second member onto one end of said first member, whereby said first and second members create a friction-fit therebetween; and (c) inserting another end of said first member into a convex surface side of said core member and into said step tube, whereby said step tube and said other end of said first member creates a friction-fit therebetween, said first member being pushed into said step tube by a distance sufficient to move said diagonally-aligned flange adjacent to a marginal portion of said core surrounding the opening in said core.

17. The method of claim 16 further comprising providing at least one annular-shaped, diagonally aligned weakened area on said first member adjacent to said diagonally-aligned flange to enable an end of said first member holding said second member to easily break away from said other end of said first member at said weakened area when cast material, which is poured into the mold assembly, has set and the cast member is separated from the mold.

18. A method for embedding inserts in a cast member, comprising: providing first and second sets of holding pins, each set arranged along spaced intervals of an associated elongated support; mounting an insert on each of said holding pins; releasably securing said support along an exterior surface of a core member of a mold assembly with the support being aligned to position the holding pin sets in spaced, substantially parallel fashion; and placing cast material in the mold assembly so as to embed the inserts into the cast material.

19. The method of claim 18 further comprising: separating said core member from said cast member after the cast member has been set, thereby releasing the supports from said core member.

20. The method of claim 19, further comprising: prying the supports away from said cast member while said inserts remain embedded within the cast member.

21. The method of claim 20, further comprising: inserting cooperating legs of a step member into an associated pair of inserts.

22. The method of claim 18 further comprising: providing at least one template having a pair of alignment edges; and placing said supports along opposite sides of the template whereby one side edge of each support engages an associated one of said alignment edges to control the spacing distance between said supports and thereby controlling the spacing distance between the sets of holding pins.

23. The method of claim 22 wherein said template is further employed to maintain said supports in spaced parallel fashion.

24. The method of claim 22 wherein the step of placing the template between said supports further includes releasably securing the template to said core member.

25. The method of claim 24, further comprising: removing the template releasably mounted to the core after the supports have been aligned and before placing cast material into the mold assembly.

26. The method of claim 18 wherein the step of releasably mounting the supports to said core member further comprises: providing a magnetized member on said core member having at least a surface portion upon which the supports are to be mounted; and the step of providing said supports further including providing a member along a surface of said support opposite the surface from which the holding pins are mounted and which is magnetically attractive to said magnetized member for releasable mounting the supports to said core.

27. The method of claim 26, further comprising: providing a pair of templates each having a permanent magnet member on one surface thereof for placement against the core formed of a material which is magnetically attracted to the magnet members; and placing said supports against opposite parallel edges of said templates to properly align said supports a given distance apart on said core.

28. The method of claim 27, further comprising: the step of removing the templates from said core after the supports have been properly aligned and before placing cast material into the mold assembly.

29. An insert for receiving and supporting a leg of a step, comprising: a hollow body closed at one end and open at an opposite end for force-fittingly receiving and supporting said leg; an interior of said hollow body having a plurality of annular, spaced, inwardly directed projections for engaging and retaining the leg of the step therein; and said interior further having plurality of substantially linear, axially aligned spaced projections located near said closed end and adapted for receiving and engaging a positioning pin inserted into the hollow interior preparatory to a casting operation to form a force fit with the positioning pin.

30. The insert of claim 29, wherein said axially aligned projections terminate a spaced distance inwardly from said open end so as not interfere with a function of the annular projections provided for retaining said leg in said insert.

31. In combination a plurality of inserts, insert positioning assemblies and an interior core of a mold assembly having at least one planar surface portion, comprising: said insert positioning assemblies comprising first and second elongated supports having a plurality of holding pins arranged at spaced intervals along each of said supports; said inserts each comprising a hollow shaped body having an open end for mounting on an associated one of said holding pins each inserted into one of said open ends; each elongated support having a magnet assembly arranged on a surface of each elongated support opposite the surface upon which said holding pins are mounted; said planar portion of said mold assembly inner-core having magnetically attractive means arranged therealong; said elongated supports being placed upon said planar region and being magnetically attracted thereto; and an alignment template provided with permanent magnet means along at least a portion of one surface thereof; and said template having at least one pair of opposite parallel sides and being positioned on said inner core so as to be magnetically attracted to said magnetically attractive means and between and abutting adjacent sides of said elongated supports to properly position said supports in parallel fashion and at a given spacing.

32. The combination of claim 31 wherein said insert is provided with a hollow interior having annular projections to facilitate gripping of a leg of a step insertable into said hollow interior; and a plurality of axially aligned spaced projections provided in a region extending from a closed end of said insert toward and terminating a spaced distance inward from said open end to provide a force fit with an associated positioning pin.

33. The combination of claim 31 wherein said permanent magnet means provided on said elongated supports comprises permanent magnet means embedded in a suitable plastic material.

34. The combination of claim 31 wherein said magnetically attractive means of said inner-core member comprises at least said planar portion of said core member being formed of a metal which is magnetically attractive to a permanent magnet.

35. In combination a plurality of inserts, insert positioning assemblies and an interior core of a mold assembly having at least one planar surface, comprising: said mounting assemblies comprising first and second elongated supports having a plurality of holding pins arranged at spaced intervals along one surface each of said supports; said inserts each comprising a hollow shaped body having an open end for mounting on an associated one of said holding pins; each elongated support comprising a magnetically attractive material; said planar portion of said mold assembly inner-core having magnetic means arranged therealong; said elongated supports being placed upon said planar region and being magnetically attracted to said magnetic means; and an alignment template provided with magnetically attractive means along at least a portion of one surface thereof; and said template having at least one pair of opposite parallel sides and being positioned on said inner core so as to be magnetically attracted to said magnetic means and between and abutting adjacent sides of said elongated supports to properly position said supports in spaced parallel fashion.

36. An insert adapted to be embedded in a cast member for force-fittingly receiving a leg of a step, said insert comprising: a hollow, substantially cylindrical-shaped elongated housing having an open end and a closed end; one of said ends having a flange lying in a plane diagonally aligned with a longitudinal axis of said housing; an interior surface of said housing having a portion thereof being provided with a plurality of projections arranged at spaced intervals and extending radially inward to facilitate gripping of said leg.

37. The insert of claim 36 further comprising: a holding portion projecting away from the housing for engaging an opening in a support member for retaining the insert on the support member.

38. The insert of claim 36 wherein said flange at said open end covers a marginal portion surrounding an opening in a support member for retaining the insert on the support member and to prevent seepage of a cast material therethrough.

39. The insert of claim 36 wherein said housing is provided with a second plurality of flanges extending radially outwardly from said housing and spaced along the housing for retaining the insert in place when embedded in a cast member.

40. The insert of claim 36 wherein said closed end seals an opening in a mold core of a mold assembly preparatory to insertion of a cast material into the mold assembly.

41. The insert of claim 36 wherein each of the plurality of projections have a tapering cross-section defined by first and second sides transverse to the longitudinal axis.

42. The apparatus of claim 1 wherein said projections are arranged at spaced intervals and extend radially inward.

43. The apparatus of claim 1 wherein each of the internal projections have a tapering cross-section defined by first and second sides transverse to the longitudinal axis.

44. The apparatus of claim 1 wherein said projections are annular projections arranged at spaced intervals and extend radially inward.

45. A method for embedding inserts in a cast member, said inserts being comprised of a hollow, substantially cylindrical-shaped elongated support portion, a hollow, substantially cylindrical-shaped elongated insert portion having interior projections for gripping a leg of a step and a diagonally aligned flange between said holding portion and said insert portion; said method comprising the steps of: (a) providing a mold assembly including an annular-shaped core member having at least one opening and a tubular step tube joined to the core member and aligned with said opening and extending inwardly from a concave surface of said core member; and (b) inserting one end of said holding portion into a convex surface side of said core member and into said step tube, whereby said first member is force-fitted in said step tube, said holding portion being pushed into said step tube by a distance sufficient to move said diagonally-aligned flange adjacent to a marginal portion of said core surrounding the opening in said core.

46. The method of claim 45 further comprising providing at least one annular-shaped, diagonally aligned weakened area adjacent to said diagonally-aligned flange; placing cast material into the mold assembly; and separating the cast member from the mold assembly causing the holding portion to break away from the insert portion along said diagonally aligned weakened portion; and inserting the leg of the step into said insert portion.

47. The combination of claim 31 wherein said magnet assembly comprises a plurality of permanent magnets arranged in recesses in said opposite surface; and epoxy material for retaining said magnets in said recesses.

Description:

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation-in-part of U.S. patent application Ser. No. 09/395,106, filed Sep. 14, 1999, which is incorporated by reference as if fully set forth and which claims priority from provisional application Ser. No. 60/100,234, filed Sep. 14, 1998 and which provisional application is also incorporated by reference as if fully set forth.

FIELD OF THE INVENTION

The present invention relates to method and apparatus for producing cast concrete members and the like and more particularly to a method and apparatus for producing cast members which are provided with step inserts to facilitate insertion and firm gripping of steps in cast members. One embodiment of step inserts is designed to prevent undesirable seepage of the cast material and thereby retain the cast material within the mold assembly. Novel one-piece or two-pieces insert assemblies are provided to retain the insert in proper position during casting. The two-piece step inserts are designed to adapt to a variety of installation applications. Templates are provided for easily and accurately locating step inserts employed in cast members at least one flat wall.

BACKGROUND OF THE INVENTION

It is well known in the art to provide manhole assemblies with steps to facilitate a descent into and ascent from the manhole assembly through a top opening thereof.

One of the preferred techniques is described, for example, in U.S. Pat. No. 3,974,615 issued Aug. 17, 1976, assigned to the assignee of the present invention, which patent teaches the use of hollow plastic manhole step inserts releasably mounted to an inner mold member of a mold assembly. The cast

    • material is poured into the mold assembly and when set, the cast member is withdrawn from the mold assembly. Mounting flanges provided at the open end of the manhole step inserts are arranged to break away from the main body portion of the manhole step insert when the cast member is lifted out of the mold assembly, leaving the manhole step inserts imbedded in the cast material. A pair of such inserts is adapted to receive the free ends (i.e. legs) of a substantially U-shaped step member, which free ends are force-fitted into the hollow manhole step inserts forming an excellent force-fit there between.

Known inserts are preferably made of polypropylene which has a life expectancy exceeding concrete itself and further exhibits excellent chemical resistance and serve as a protective shield against dissimilar material reaction such as an electrolysis of aluminum and concrete. The insert meets requirements of all ASTM C-478 § 12 and Performance Test Procedures of ASTM C-497.

A number of conventional step members utilized in manhole assemblies and the like have been provided with substantially rectangular and in most cases square-shaped, cross-sectional shapes. Other step members adapted for insertion into the step inserts are designed to have circular cross-sections. In addition, as can be seen from FIG. 1, a major portion of the insertable portion of each leg of the step is provided with a generally saw-tooth-shaped configuration wherein the saw-tooth configuration is of such a nature as to facilitate insertion of the legs of the step into each step insert while providing a frictional fit of significantly increased gripping force which acts against a force acting in the direction to withdraw the step legs from the insert.

The steps of circular cross-section thus require a step insert of a design and shape which conforms with and cooperates with the design and shape of the steps whose legs are adapted to be inserted therein.

Manhole assemblies are typically produced through either a drycast or a wetcast method, both of which methods are well known in the art.

Utilizing one conventional drycast method, the granulated casting material is placed into the mold assembly which is vibrated and packed down to assure that the dry casting material is evenly and densely packed within the mold assembly. When the casting material has been filled to the appropriate level within the mold assembly and appropriately compacted, the core portion of the mold extends a pair of reciprocating pins, which are operated by either hydraulic or pneumatic means, into the casting material to form openings within the cast material of a size appropriate for receiving the legs of a step. In the conventional technique, the tremendous pressures developed within the casting material cause these openings to “sag” or become “off-round” when the pins are removed and the openings often accumulate some of the cast material when the cast member is removed from the mold assembly which necessitates that the operators employ a drill or other device to reopen or “reround” the openings to enable the legs of a step to be inserted therein.

The pneumatically or hydraulically-operated pins which create the step openings in cylindrical-shaped case members typically extend from a core mold member which has a curved, convex outer periphery. The casting material entering into the openings in the region between the pins and the opening in the core member through which the pins extend, often renders the pins inoperative and possibly even causing damage to the mechanism. At the minimum, the entry of fines into the mechanism require regular maintenance to maintain the mechanism in operating condition, which disadvantages are to be avoided.

In the employment of the wetcast method, there has heretofore been no step insert available which is inserted into the casting material by hydraulically or pneumatically operated pins.

BRIEF DESCRIPTION OF THE INVENTION

The present invention, in one embodiment, is characterized by comprising a step insert design for use with manhole steps having circular-shaped insertion portions, said insert having a substantially circular cross-section and being provided with an open end and closed end. The closed end has a conical-shaped outer surface. The insert is designed to fit over a free end of a circular-shaped, reciprocating pin and is provided with inwardly directed projections which are parallel to the longitudinal central axis of the insert and are located near the closed end of the insert so as not to interfere with the continuous, annular projections arranged along the interior surface of the insert and provided for firmly gripping the leg of a step inserted into the insert.

The insert is mounted upon the pin and, when properly positioned, has a diagonally aligned flange at its open end which is substantially flush with the convex surface of the mold assembly core member, which flange has an outer diameter that is just slightly less than the inner diameter of the opening in the core mold which it substantially seals, to prevent seepage of fines into the mold assembly mechanism.

The outer periphery of the insert is provided with a plurality of radially outwardly extending annular flanges therealong which serve to significantly enhance the holding power of the dry cast concrete upon the insert.

The closed end of the insert may, if desired, be increased in thickness as compared with the remainder of the insert to significantly enhance the structural strength of the insert as it is pushed into the drycast material.

As described above, the interior periphery of the insert, in one embodiment, is provided, in one embodiment, with closely spaced projections forming annular serrations of a “one way” type in that the tapered, annular projections are preferably diagonally aligned along one surface thereof so as to make it easier to insert the leg portion of a step while the opposite surface is substantially perpendicular to the longitudinal axis of the insert, thereby significantly increasing the frictional fit between the leg portion and the insert to act against forces working in the direction of removal of a leg of a step out of the insert. The interior surface adjacent to the inner most end is also provided with a plurality of inwardly, directed projections to provide a good friction grip with the reciprocating mounting pin extending through the mold member to retain the insert in its proper position during casting of the cast member.

Another step insert utilized in the fabrication of the cast members has an open end and a closed end. The open end lies in a plane which diagonal to a longitudinal axis of the insert and is provided with a flange adapted to rest against an opening in the mold assembly core member. A plurality of flexible, hook-like ears or projections extend away from the diagonally aligned flange and are arranged, preferably at equiangularly spaced intervals about the insert so as to make a snap-fit with a marginal portion of the opening to hold the insert in position preparatory to filling of the mold assembly with cast material. The flange surrounding the open end substantially seals the opening to prevent fines from entering into the mold assembly mechanism.

The ears are designed to snap off due to a shearing force applied thereto as the cast member, after having been set, is separated from the mold form.

Heretofore, inserts utilized in the wetcast method for providing inserts for circular-shaped step members employ a pin which is inserted into the mold assembly during casting. The pin is then removed from the cast member after it has set and is removed from the form. This technique requires an undesirable additional manufacturing step and further fails to provide an opening for the leg of the step which has the supporting strength and holding force of the insert of the present invention.

Another preferred insert embodiment for use in the wetcast method is comprised of an assembly of first and second hollow, cylindrical-shaped, molded plastic members. A first member, which serves as a tube holder, has a diagonally aligned flange intermediate its open end and has axially aligned slots on opposite sides of the flange. A bead provided on one end of the first member slides into a step tube welded to a mold core member and is aligned with an opening in the core. The slots allow the first member one end to be pressed inwardly by the tube, providing a good press-fit between the step tube and the first member. Alternatively, the slot on the opposite sides of the member may be omitted while still providing a suitable force-fit into both the second member and the step tube.

The second member serves as the insert and generally resembles one of the embodiments described above and has a open end and a closed end. The open end lies in a plane which forms a right-angle with a longitudinal axis of the insert and is provided with a flange adapted to rest against an opening in the mold assembly core member. The end of the first member extending away from the step tube is force-fitted into the open end of the second member. The diagonally-aligned flange on the first member, engages a marginal portion of the core surrounding the opening in the core to hold the insert assembly in the proper position and to further seal the opening in the core mold member as the casting material is poured into the mold assembly.

The first member is scored at least in the region of the diagonally-aligned flange on the side of the first member extending into the cast member, enabling the portion of the first member embedded in the cast member to easily break away from both the second member and the insert embedded in the cast member when the cast member, after having set, is separated from the mold assembly. The portion of the first member remaining in the step tube is removed from the step tube in readiness for receipt of a first member of another insert assembly in preparation for molding another cast member. The portion of the first member remaining in the second member is pushed toward the closed end of the second member when a leg of a step is inserted or may be removed prior to insertion of the leg of a step.

Another embodiment of the present invention is to provide method and apparatus for imbedding inserts within a box-like cast member having an interior typically comprised of a plurality of walls each having planar surfaces. Steps can be placed at different areas along the flat surfaces of such box-like structures to suit the particular application. One present day technique is to drill holes in the finished product at a location where steps are required. This technique is very time consuming and labor intensive. In order to greatly simplify the precise location of inserts for steps, a unique method and apparatus of the present invention comprises the provision of a pair of substantially rigid elongated plates having pairs of holder pins arranged at spaced intervals along each plate. Two additional plates employed as spacing templates are arranged between the first and second elongated plates and preferably near upper and lower ends thereof so as to provide the proper spacing between the elongated plates and hence between the holder pins. The elongated plates and templates are, in one preferred embodiment, comprised of a rigid metallic strip and a sheet of plastic material affixed to the metal plate and homogeneously impregnated with magnetized particles, said impregnated sheet being affixed to one major surface of each of the elongated strips opposite the surface carrying the holding pins. In another alternative embodiment, recesses may be formed in the surface of the rigid metal strip opposite the surface along which the pins are mounted. Permanent magnets are placed in the recesses and an epoxy is applied to the surface carrying the permanent magnets to retain them in place. The strips and templates are affixed to the wall of an interior or “core” mold member of a mold assembly which core is formed of a ferromagnetic material attractive to the magnetized sheet (or permanent magnet members). When the elongated strips and templates are properly positioned with longitudinal sides of said strips abutting opposing side edges of the templates, the templates may then be removed. Inserts are press fitted onto the holding pins and the cast material is poured into the mold assembly.

When the cast material has set, the cast member is removed from the mold assembly. The embedded inserts and holding pins are lifted together with the cast member, the lifting forces overcoming the magnetic attraction of the magnetized sheets (or permanent magnets) to the surface of the mold core so that the elongated strips and magnetized sheets are stripped from the inner mold member.

The elongated strips carrying the pins are then peeled away from the interior wall of the cast member, leaving the inserts embedded within the cast member. The steps are then pushed into the inserts thereby completing the procedure.

The templates and elongated strips bearing the positioning pins are reusable and in fact have a long useful operating life.

In an alternative embodiment wherein the mold assembly is formed of a material which is neither ferromagnetic nor metallic such as wood, aluminum or plastic, the elongated strips and templates are magnetically attracted to a planar wall of the mold form upon which inserts are to be provided by placing a magnet or magnets on or beneath an interior surface of the hollow interior mold member opposite the surface receiving the elongated strips carrying the holding pins and the templates. This embodiment enables the use of metallic forms formed of non-magnetic material as well as wooden or plastic forms.

As another alternative, an adhesive may be placed upon the rear surface of the elongated plates bearing the positioning pins and the templates, which adhesive has sufficient strength to hold the elongated plates and templates in position against the interior mold member during the positioning and pouring phases of the casting operation but which has a limited holding power, enabling the elongated strips to break away from the interior mold member when the completed cast member is lifted away from the mold core.

OBJECTS OF THE INVENTION

It is therefore one object of the present invention to provide a novel insert for cast members and which is adapted to receive the insertable leg of a step having a circular cross-section.

Still another object of the present invention is to provide a novel insert for use in a casting method and which is designed to prevent seepage of the cast material into the mechanism of the mold assembly.

Still another object of the present invention is to provide a novel step insert for use in a casting method wherein the insert has an alignment slot which is keyed to a insertion pin to assure proper mounting and alignment thereof.

Still another object of the present invention is to provide a novel insert for step members produced in either a wetcast or drycast method and having an internal serrated design which provides increased frictional holding forces acting against forces which may be applied in a direction to pull the step out of the insert.

It is still another object of the present invention to provide a novel two-piece insert for cast members produced employing the wetcast method and which is adapted to receive the insertable leg of a step having a circular cross-section.

It is still another object of the present invention to provide a novel two-piece insert for cast members produced during a casting method and which is adapted to seal the opening in the core mold member during casting of a mold member.

Still another object of the invention is to provide novel method and apparatus for casting step inserts into cast members having a flat wall for receiving the step members.

BRIEF DESCRIPTION OF THE FIGURES

The above as well as other objects of the present invention will become apparent from a consideration of the specification and drawings of the present invention, in which:

FIG. 1 is a top plan view showing a step having an insertable portion thereof provided with a circular cross section.

FIG. 2 is a cross section of an insert designed in accordance with the principles of the present invention and which is usable with the steps of FIG. 1.

FIG. 2A is an end view of the insert of FIG. 2.

FIG. 3 shows the developmental steps employed in the utilization of the step insert of FIG. 2 when using the wetcast method.

FIG. 4 shows the developmental steps employed in the utilization of the step insert of FIG. 2 when using the wetcast method.

FIG. 5 is an exploded view of a two-piece insert assembly for use in the wetcast method.

FIG. 6 shows the developmental steps employed in the utilization of the two-piece step insert assembly of FIG. 5 when using the wetcast method.

FIG. 7 is a sectional view showing first and second insert assemblies of another preferred embodiment of the present invention with the left-hand assembly being shown in exploded fashion to facilitate an understanding of the assembly and with the right-hand assembly being inserted in a core mold member.

FIGS. 7A and 7B respectively show a detailed elevation and top view of the tube holder shown in FIG. 7.

FIG. 8 is a perspective view of another embodiment of the present invention for mounting inserts upon a flat surface of a box-like structure.

FIGS. 8A-8E are developmental views showing the manner in which the embodiment of FIG. 8 is employed to embed inserts along an interior wall of a box-shaped cast member.

FIG. 8F is a perspective view showing another arrangement of the mold assembly shown in FIG. 8A.

FIGS. 8G, 8H and 8I are perspective views respectively showing alternative embodiments for the templates of FIG. 8A.

FIG. 8J is a perspective view showing an alternative embodiment of a permanent magnet arrangement which replaces the permanent magnet strip assembly and template embodiments shown, for example, in FIGS. 8 and 8A.

FIGS. 9 and 9A respectively show perspective and top plan views of an alternative embodiment for the assembly of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a step 20′ which is formed of suitable plastic material and is typically provided with a reinforcing metallic frame embedded within the plastic material, has legs 22a′ provided with a tapered, conical-shaped tip 22a-1′ which merges with a portion 22a-2′ of generally cylindrical and yet slightly tapering shape which then merges with a serrated portion 22a-3′. The serrated portion is made up of a plurality of substantially closely-spaced, individual annular flanges F, each of which has an inclined surface F1 which is inclined at an angle to a longitudinal center-line CL on a side of each flange and a surface F2 which is substantially perpendicular to the center-line CL and which is on the side of each flange remote from the free end thereof. This design is such as to make it easier for insertion of the legs 22a′ into insert 60, for example, shown in FIG. 2 whereas any effort or attempt to pull the legs 22a′ out of an insert (60) is met with an increased frictional holding force, due to the preferred, “one way” design of the serrated portions 22a-3′.

FIG. 2 shows a cross-sectional view of the step insert 60 for employment in the fabrication of assemblies made using the drycast method and FIG. 2A shows a top view of the insert looking in the direction of arrows 2A-2A of FIG. 2.

Any suitable drycast method capable of utilizing hydraulically operated insert pins may be employed with the present invention.

Making reference to FIGS. 2, 2A and 3, the drycast method employs a core member 50 having a curved convex surface which serves to form the interior surface of the cast member being formed by providing dry material in the region 51 between core 50 and outer jacket 52, which mold assembly has been shown in highly simplified fashion.

The core member 50 is provided with circular-shaped openings 50a, 50b which are precisely arranged so as to provide the proper relationship between openings formed in the cast member and the legs of a step, such as legs 22a′ of the step 20′, for example.

When the cast material reaches an appropriate level and has been sufficiently vibrated, tamped down and the like, a pin 54 is operated by suitable hydraulic or pneumatic means (not shown for purposes of simplicity) to project out of core 50 and into the casting material.

The pin assembly 54 has a cylindrical shape and is comprised of a first portion 54a of a first diameter integrally joined to a second cylindrical portion 54b having a diameter larger than portion 54a so as to form a shoulder 54c there between. At least one projection 54d is arranged at one point along shoulder 54c and extends in an axial direction along the smaller diameter portion 54a.

It should be understood that the pin assembly 54 shown is modified from conventional pins to provide the design shown incorporating the smaller diameter portion 54a, larger diameter portion 54b, ledge 54c and projection 54d.

The insert 60 shown in FIGS. 2, 2A and 3 has a substantially circular cross-section and is comprised of a closed end 60a and an open end 60b. The outer periphery 60c is provided with a plurality of outwardly directed annular flanges 60d arranged at spaced intervals there along. The closed end 60a also incorporates a flange 60e. Flanges 60d all lie within planes which are substantially perpendicular to the longitudinal center line or axis CL of insert 60. The outer surface 60f of closed end 60a is likewise substantially planar but is diagonally aligned relative to center line CL.

The open end 60b is provided with two diametrically aligned alignment slots 60g, each of which is designed to receive the projection 54d of pin assembly 54 thereby assuring that the insert is aligned with proper orientation upon pin assembly 54 as will be understood from the description set forth below.

Noting the right-hand insert 60 shown in FIG. 3, the insert is mounted upon the right-hand pin assembly 54 with projection 54d received within one of the slots 60g. The flange 60d located at the open end rests upon ledge 54c, as shown. In the right-hand position shown in FIG. 3, with the pin assembly 54 in the “ready” position and the insert 60 properly mounted and aligned thereon, it can be seen that the planar surface 60f is substantially flush with the curved convex surface of core 50 and that the flange 60e serves to substantially completely seal opening 50b, preventing seepage of the casting material into the core assembly.

When the cast material has been duly and properly vibrated and compacted, the hydraulic (or pneumatic) mechanism (not shown) operating pin 54, moves the pin assembly 54 in the direction shown by arrow A1, urging the pin and the insert 60 mounted thereon into the cast material so as to ultimately occupy the final position shown by the left hand-insert 60′. The pin assembly 54 is designed so as to cause the ledge 54c to partially enter into the cast material, whereby the open end of the insert 60′ is slightly recessed into the cast member so that when the pin assembly 54 is withdrawn from the cast member into the mold core 50 there is no wiping action of the insert 60′ against the core, thereby preventing both the core 50 and the cast member (together with the insert) from being damaged and to prevent the cast material from swept into the core 50.

The insert 60 is provided with slots 60g at two (2) diametrically opposed positions in order to provide an insert of universal design. The manner of use is such that the slot 60g which receives projection 54d aligns the insert 60 so that the diagonally aligned end 60f is flush with the concave surface of the core. By rotating the second insert 60′, 180° relative to the first insert 60 and placing this insert 60′ on the left-hand pin assembly and so that the opposite slot 60g receives pin 54d, this assures that the diagonally aligned closed end 60f′ is flush with the curved surface surrounding the left-hand opening 50a when initially positioned on the left-hand pin 54.

As can be seen from the embodiment shown in FIG. 2, the wall of the insert in the portion 60j as well as the closed end portion 60f, may be of increased thickness to provide sufficient structural strength to enable the insert to retain its shape as it is pushed into the cast material during the practice of the drycast method. Alternatively, the thickness may be regulated to enhance or decrease cycle time. The amount of material may be reduced by providing cavities in the insert.

In equipment used for the drycast method wherein the interior region containing the hydraulically operated pins 54 is easily accessible, the inserts may be placed upon the pins when they are in a retracted position such as the left-hand pin 54 shown in FIG. 3. Alternatively, preparatory to insertion, vibration and tamping of the cast material, the pin assembly may be operated to extend into the region 51 whereupon the insert is placed upon the pin and properly aligned so that the projection 54d is received by the appropriate slot 60g and thereafter retracting the pin assembly 54 to the “ready” position shown by the pin 54 in the right-hand position of FIG. 3. It should be noted that the arrangement of FIG. 3 can also be used to make cast members employing the wetcast method.

In some applications, wherein the openings 50a, 50b in the core member 50 is at least slightly greater that the outer diameter of the flanges 60d, the pins 54, together with the inserts 60, 60′ mounted thereon my be retracted from the region 51 between the outer jacket 52 and inner core 50 during the casting operation. Nevertheless, the pins 54 and inserts 60, 60′ may be employed using either of these two (2) techniques.

FIG. 4 shows an insert 60″ employed in the manufacture of cast members using the wetcast method. In the utilization of mold assemblies employed in the wetcast method, the internal mold member or core 56 is provided with a pair of openings 56a, 56b similar to the openings provided in core 50 shown in FIG. 3. The insert 60″ differs from the insert 60 (and 60′) in that the closed end 60f′, although being a planar surface, is aligned so as to be perpendicular to the center line CL of the insert 60″. However, the closed end may be diagonally aligned with center line CL or may be conical-shaped, if desired.

The open end of insert 60″ is further modified so that the flange 60d″ immediately adjacent the open end lies in a plane which is diagonally aligned relative to center line CL. A plurality of ears 60h are integrally joined to the insert adjacent to the flange 60d″ and project away from the opening and are substantially parallel to the longitudinal axis CL. Each ear 60h has a substantially hooked-shaped configuration and each ear is sufficiently flexible so that, as the ears are pushed into opening 56a, the inclined surfaces 60h-1 slidingly engage the edge of the opening and cause the ears to be flexed substantially radially inwardly until the inclined surfaces 60h-1 clear the interior side of the opening, at which time the locking surface 60h-2 of each ear 60h grips a marginal portion of the inner mold member 56 surrounding opening 56a on the interior side of core 56 as the flexed ears return to their normal unflexed position, whereby the insert 60″ is locked into position with the ears engaging marginal portions along the interior concave surface of core 56 while flange 60d″ rests against a marginal portion surrounding the exterior convex portion of the core 56 surrounding opening 56a. Flange 60d″ prevents fines from entering into the interior of the mold member 56.

The insert 60″ utilized for both the left and right-hand positions, i.e., for insertion into the left and right-hand openings 56a, 56b, are identical in design to one another. The proper orientation of the inserts relative to the mold member 56 is obtained by rotating each insert so that the flange 60d″ rests against the external, curved convex surface of core 56. Thus, the insert inserted into the right-hand opening 56b is rotated 180° about its center line relative to the insert inserted into opening 56a so that the inserts are aligned with their longitudinal axes CL substantially parallel to one another to assure proper alignment with the insertion portions of step 20′ (see FIG. 1). The ears 60h are preferably aligned at equiangular intervals. Preferably, at least three (3) ears are provided at 120° intervals. Alternatively four (4) ears may be provided arranged at 90° intervals. A greater number of ears may be provided if desired.

After the inserts are snapped into position, the cast material is poured into the mold. When the cast material has been set, the cast member is pulled out of the form, whereupon the ears 60h shear off as the cast member is removed from the mold. The ears 60a are of a strength sufficient to retain the inserts in position during the casting operation and yet adapted to be easily sheared away from the main body of the insert when the cast member has been set and is pulled away from the mold.

The interior design of the insert 60″ is substantially identical to the design of insert 60 to preferably obtain the “one way” feature of the internal serrations for assuring the positive retention of the legs of the step within the inserts.

The inserts 60″ may be modified for use in core molds having flat walls by aligning flange 60d″ perpendicular with the center line CL.

Testing has indicated that the inserts 60 and 60″ are capable of withstanding as much as four (4) times the normal pulling force (1600 lbs. pulling force), the normal pulling force being of the order of 400 lbs. capability.

The two-piece insert assembly embodiment 70, shown in exploded fashion in FIG. 5, is comprised of first and second hollow, cylindrical-shaped, molded, plastic members 72 and 74. Member 72 has open ends 72a and 72b. A flange 72c provided intermediate ends 72a and 72b lies in a plane which is diagonally aligned relative to the central axis CL. Two (2) slots 72d are arranged at 180 degree intervals about the end 72b of member 72 and extend inwardly from end 72b toward flange 72c. Another set of two (2) slots 72e are arranged at 90 degree intervals about the end 72a of member 72 and extend inwardly from end 72a toward flange 72c. However, the inward end of slots 72e terminate a spaced distance from flange 72c. If desired, the number of slots 72d, 72e may be three or even four or more slots arranged a equi-spaced intervals about the circumference of member 72.

The major portion of member 72 extending between and 72a and flange 72c has a plurality of individual annular projections F′, similar to the projections F on the step 20, each of which has an inclined surface F1′ which is inclined at an angle to a longitudinal center-line CL, on a side of each projection and a surface F2′, which is substantially perpendicular to the center-line CL and which is on the side of each projection remote from the end 72a. Alternatively, the surface F1′ may be aligned perpendicular to the central axis CL. This design is such as to make it easier for insertion of the end 72a into insert member 74, whereas any effort or attempt to pull the insert member 74 out of insert member 72 is met with an increased frictional holding force, due to the “one way” design of the serrated or flanged portions F′.

Insert member 74 has a closed end 74a and an open end 74b. End 74a has a planar surface which is diagonally aligned relative to center line CL and terminates in an integral annular flange, similar to the embodiment 60 shown in FIG. 2. The exterior of member 74 is further provided with a plurality of integral annular flanges 74c and 74c′, all of which are substantially planar and lie in planes forming right-angles with the center line CL.

The interior periphery of member 74 is provided with a plurality of closely spaced, inwardly directed, annular projections F″, having an inclined surface F1″ which is inclined at an angle to the longitudinal center-line CL and a surface F2″ which is substantially perpendicular to the center-line CL and which is on the side of the projection remote from the end 74b. This design is such as to make it easier for insertion of the end 72a into insert member 74, whereas any effort or attempt to pull the insert member 74 out of insert member 72 is met with an increased frictional holding force, due to the “one way” design of the projections which form a serrated configuration. The “one way” design also more effectively holds the leg of a step when inserted into the insert 70. Nevertheless, both sides of the projections may be diagonally aligned, if desired.

The manner in which the insert assembly 70 is employed in the wetcast method will now be explained making reference to FIG. 6.

The core mold member 76 is provided with a pair of circular-shaped openings 76a, 76b. Step tubes 77, 78 are preferably welded to the core member 76 in the manner shown. The end of each step tube joined to mold core 76 is defined by an edge which lies in a plane that is diagonally aligned to the longitudinal axis of the step tube. Each step tube is aligned with its associated opening 76a, 76b and further so that the step tubes are parallel to one another.

Member 72′ is inserted into opening 76a from the convex surface side of core 76 and enters into step tube 77. The integral bead 72f at the open end 72b has an outer diameter which is greater than the inner diameter of opening 76a and step tube 77, causing the sides of member 72a to be pressed inwardly providing a force-fit. The sides of member 72′ are yieldable due to the slots 72d. Member 72′ is pushed into tube 77 until the flange 72c′ engages the marginal portion of core 76 surrounding opening 76a. Member 74′ is then pushed onto member 72. The slots 72e′ enable the sides of member 72′ to yield while providing a good force-fit between members 72′ and 74′. The one-way projections F′ and F″ make it easier to telescope member 74′ onto member 72′ while providing a snug fit as well as making it harder to pull members 72 and 74 apart.

Flange 72c′ substantially seals opening 76a, preventing fines from entering into the opening 76a. It should be understood that an insert assembly 70″ is mounted upon opening 76b in a similar fashion to that described above with regard to assembly 70. Alternatively, member 74 may be telescopingly mounted upon member 72 before member 72 is inserted into step tube 77.

When the insert assemblies have been properly mounted upon core 76, the casting material is poured into the mold assembly. After the casting material has set, the cast member separated from the mold assembly. Member 72 is scored in two (2) places in the region of flange 72c. The two substantially annular-shaped scored regions 72g, 72h respectively located above flange 72c and just below the annular projection F′ closest to the diagonal flange 72c and just below the diagonal flange 72c, preferably are formed by reducing the thickness of the first member in these regions as shown best in FIG. 5, to facilitate breaking away of the portion of member 72 between diagonally-aligned flange 72c and the annular projection F′ closest to flange 72c. The first member 72 thus breaks into three (3) or at least two (2) parts, so that the portion having the annular projections F′ remains inside of second member 74; the portion between the flange 72c and end 72b remains inside of the step tube 77 and the remaining portion intermediate the portions remaining inside member 74 and step tube 77 breaks free of the other two portions.

The shear line 72g is located so that the portion inside member 74 breaks into two parts, thereby simplifying its removal from member 74. The portion of the members 72 remaining in each step tube is also easily removed preparatory to the molding of the next member to be cast. The intermediate portion falls free of the core member 76 and the cast member when it is removed from the mold assembly.

Another preferred embodiment of a two-piece insert 80 is shown in FIGS. 7 through 7B, which is breakaway insert preferably for use in wet cast installations and comprises a main insert body 81 of a substantially cylindrical shape having a closed end 81a and an open end 81b, the open end being surrounded by a diagonally aligned annular flange 81c. The interior of the insert body 81 is provided with continuous annular projections extending radially inward for gripping a leg of a step insert therein. The projections may be similar to those shown in FIG. 2 wherein one side of each projection is diagonally aligned relative to center line CL and the other side of each projection is substantially perpendicular to center line CL. Alternatively, both sides of each projection may be diagonally aligned relative to the center line CL.

A tube holder 82 has upper body portion 82a and a lower body portion 82b joined at an intermediate shoulder 82c. The interior of holder 82 tapers at 82d to provide an annular, diagonally aligned region of reduced thickness relative to the upper body portion 82a and lower body portion 82b of the tube holder 82 to control breakage in the region of the shoulder 82c. More particularly, the inner diameter of upper body portion 82a just above shoulder 82c is larger than the inner diameter of upper body portion 82a at shoulder 82c, forming a diagonally aligned interior surface 82d. Upper body portion 82a telescopes into the interior of insert 81, shoulder 82d resting against flange 81b radially outwardly extending from insert 81. Upper portion 82a is preferably slightly tapered, increasing in diameter moving from the top end 82a-1 to the shoulder 82c, forming a force-fit when tube holder 82 is telescoped into the open end of insert 81. It should be understood that the tapered configuration of tube holder portion 82a may be employed to replace the serrated portion F′ of the holder 72′ of FIG. 6. Also, the tapered configuration eliminates the need for the slots 72e. Lower end 82b of tube holder 82 is provided with a plurality of fins (preferably three) 82e integral with tube holder 82 and preferably arranged at equi-spaced intervals about the outer periphery of lower end 82b. Fins 82e each have flat surfaces 82e-1 and their diagonally aligned edges 82e-2 and 82e-3 project away from the outer surface of the tube holder by a small distance, typically of the order of 0.012″. In addition, the interior of the lower half 82b of holder 82 is tapered, increasing in diameter from bottom end 82b-1 to shoulder 82c (the preferred embodiment has a taper of the order of 0.25″). The slightly outwardly extending edges 82e-2, 82e-3 of fins 82e provide a force-fit with each one of the pair of steel tubes 84 and 86, each of which receive a lower end 82b of a holder such as lower end 82b of tube holder 82, to thereby retain the tube holders within the tubes 84, 86 during the casting operation.

Tubes 84 and 86 have their ends, 84a, 86a welded or otherwise secured to the manhole mold core 88 which forms the inner mold member or core of a mold assembly used to cast manholes. The tubes extend inwardly into the hollow interior of the core 88 and are arranged in spaced parallel fashion. It should be noted that tubes 84 and 86 do not require slots or “keyways” since the edges 82e-2 and 82e-3 of fins 82e provide a good force-fit with interior surface of tubes 84, 86. The fin arrangement may be employed to replace the bead 72f and slots 72d in the holder 72 shown in FIG. 5. Flange 81c at the open end 81b of insert 81 is aligned so as to be substantially parallel to the curved surface of the manhole mold core 88 to prevent the cast material from entering into the holders 84, 86. Alignment between the tube holders and tubes is assured by aligning the shoulder 82c with the opening in the core.

In use, inserts 81, 81′ are each mounted upon a tube holder 82, 82′ and the lower ends of each tube holder 82, 82′ is inserted into one of the tubes 84 and 86 with the edges 82e-2, 82e-3 of fins 82e holding the tube holders in tubes 84 and 86.

Cast material, such as concrete is poured into the mold assembly and, after the cast member is set, the cast member is separated from the mold assembly, causing the upper halves 82a of each tube holder to break away from the lower halves 82b along the score lines 82c of each tube holder, each upper end 82a being retained within insert 81, whole the lower ends 82b are retained within the steel tubes 84 and 86. The broken away ends 82b are then removed and discarded preparatory to a subsequent casting operation.

In order to insert the legs of the manhole steps, the legs are pushed into the open ends 81b of the inserts 81. The upper ends 82a of the tube holders remaining in the inserts 81 are driven toward the closed ends 81a of the inserts 81 as the legs of the steps are forced fitted into the inserts. Alternatively, the upper portion 82a may be removed from the interior of insert 81.

The tube holders 82 need not be used when other positioning means are employed. As one example, the inserts may be mounted on positioning pins employed, for example, in dry cast installations, thereby greatly increasing the versatility of the two-piece design shown in FIG. 7.

The interior periphery of the insert 81 is preferably substantially identical to the interior of the embodiment shown in FIG. 6 greatly facilitating insertion of the legs of a manhole step while making it extremely difficult to remove steps after they have been inserted. The interior annular projections also provide a good friction fit with the upper ends of tube holders 82. In addition, the portion of the interior of each insert 81 adjacent the closed end 81b is provided with a plurality of elongated projections 81d which are parallel to the central longitudinal axis of insert 81 and hence are parallel to one another. The projections extend radially inwardly from the interior of the insert and provide a good force-fit with a mounting pin when mounted thereon as shown, for example, in the embodiment of FIG. 8 wherein insert 81 is mountable upon one of the mounting pins such as mounting pin 91b. The projections 81d provide insert 81 with increased versatility, making it usable with the holder 82 as well as being usable on a mounting pin and without the holder 82. The projections 81d are located inward from open end 81c by an amount sufficient so as not to interfere with a free end of a leg of a manhole step inserted into the insert 81.

In box-shaped enclosures employed in sewage and water handling systems, the cast members typically have four interior planar surfaces, any one of which may be selected for the embedment of inserts for manhole type steps. However, it is both expensive and wasteful to provide for embedment of a plurality of sets of inserts along each interior wall since only one set of steps is sufficient. In situations requiring a decision as to which planar wall to provide for the embedment of inserts prior to installation of the cast member, the conventional technique was to drill holes in the desired wall for each of the inserts after the cast member has been formed and then mount inserts into each drilled opening, which technique is time consuming, labor intensive and costly.

Another embodiment of the present invention is characterized by comprising method and apparatus for embedding inserts which is greatly simplified as compared with conventional techniques and which permits selection of any of the interior planar surfaces of the box like cast member to utilize as that surface or wall of the cast member which is to receive the inserts.

Making reference to FIG. 8, apparatus is shown therein which is comprised of first and second elongated assemblies 91 and 92. Elongated assemblies 91 and 92 are each comprised of a rigid metallic plate 91a, 92a such as steel, formed into an elongated strip. Each metallic strip 91a, 92a is provided with a plurality of pins 91b, 92b secured at spaced intervals along each strip and extending outwardly therefrom. The pins may be mounted to the strips in any suitable fashion. The embodiment shown employs fasteners F (see FIG. 8B).

A plastic sheet 91c, 92c is affixed to each of the rearward surfaces of the metal strips 91a, 92a. The plastic sheets 91c, 92c are each impregnated with a magnetized ferro-magnetic material which is preferably homogeneously dispersed throughout the sheets 91c, 92c. Each sheet 91c, 92c is secured to the surface of the metal strips 91a, 92a opposite the surface from which the pins 91b, 92b project. The adhesive is chosen to assure a high strength adhesion of the sheets 91c, 92c to the plates 91a, 92a for a purpose to be more fully described.

As is mentioned above, pins 91b, 92b may be affixed to strip assemblies 91, 92 in any suitable fashion. However, a preferred technique is to drill holes 91d, 92d, as shown in FIG. 8B and insert threaded fasteners F for threadedly engaging tapped openings in the holding pins 91b, 92b.

FIG. 8A shows the manner in which the strip assemblies 91 and 92 are utilized.

FIG. 8A shows the interior or core member 94 which is comprised of a hollow, substantially rectangular-shaped shell which defines and forms the four interior surfaces of a cast member. Although not shown for purposes of simplicity, it should be understood that an outer jacket, which is placed around the perimeter of pedestal 93, surrounds the core 94 to define a hollow interior space which receives the cast material, typically a composition including cement. Only a small portion of the outer jacket 97 is shown in FIG. 8a for purposes of simplicity, it being understood that the outer jacket 97 completely surrounds the inner core 94 and is of a conforming or substantially rectangular shape.

In order to assure the proper positioning between assemblies 91 and 92, a pair of rectangular-shaped templates 95 and 96 are provided, each having plastic sheets 95c, 96c, impregnated with magnetized particles. The templates are positioned between strips 91 and 92 as shown in FIG. 8A with the short edges 96a, 95a engaging one longitudinal side 91f of plate 91 and with the short edges 96b, 95b of templates 96 and 95 engaging the long edge 92f of assembly 92, thus assuring the proper spacing between and parallelism of the arrays of pins 91b, 92b, measured in the horizontal direction. The sheets 95c, 96c, are magnetically attracted to the core 94. In order to assure that the pins 91b of assembly 91 are the same vertical height as the associated pins 92b, cooperating alignment markers M may be placed along the edges 91f, 92f of strips 91 and 92 and along the opposite edges of templates 96 and 95 to assure that the associated pins will be vertically aligned when the markers M, provided on members 91 and 92 and the templates 95 and 96, are in alignment. To assure proper vertical orientation, a carpenter's level (not shown for purposes of simplicity) or other suitable leveling device may be utilized to assure the verticality of the assemblies 91 and 92, as is conventional. Alternatively, only one template 95′ may be provided as shown in FIG. 8G, and having plastic sheets 95d′ near the upper and lower ends. The template may have portions cut away to reduce the size and weight of the template, as shown in FIGS. 8H and 8I.

The assemblies 91 and 92 and templates 95 and 96 are aligned along surface 94a of core 94 and adhere to core 94 due to the magnetized ferro-magnetic material homogeneously dispersed throughout the sheets 91c, 92c and 95c, 96c, are magnetically attracted to the core 94 which is formed of a suitable ferro-magnetic material.

Inserts, such as, for example, inserts similar to the inserts 81 shown in FIG. 7, but with flanges at the open end which are perpendicular to the longitudinal axis of the insert, are placed on each of the pins 91b, 92b. A press fit is obtained by virtue of the inwardly radially extending elongated projections 81d provided in insert 81, as shown in FIG. 7. However, any suitable insert may be mounted on the holding pins. FIG. 8A shows the inserts identified as “I”, since assemblies 91 and 92 may be used with inserts of any design other than insert 81 and which are capable of being force-fitted to pins 91b, 92b.

With the assemblies 91, 92, inserts I and templates 95, 96 holding the assemblies 91, 92 properly in place as shown in FIG. 8A, the templates are removed and the cast material is poured into the hollow region in the mold and is typically vibrated to assure that the cast material is dispersed uniformly throughout the hollow interior of the mold assembly.

More specifically, once the assemblies 91 and 92 are properly aligned and magnetically attracted to the surface 94a of core 94, templates 95 and 96 are preferably removed. The templates 95 and 96 are preferably formed in a manner similar to the assemblies 91 and 92 in that they are metallic plates each having a plastic sheet 95c, 96c, each being formed of a plastic material having a magnetized ferro-magnetic material uniformly dispersed throughout the sheets so as to be magnetically attracted to surface 94a of the mold core 94. The templates are pried away from the mold core 94 after the assemblies 91, 92 are aligned and prior to filling the mold assembly with casting material, by a suitable tool (not shown), this operation preferably being performed in such a manner so as not to disturb the desired orientations of the assemblies 91 and 92.

After the cast member has been set, either the core 94 is lifted away from the cast member or the box-like cast member is lifted away from the core member. The separating (lifting) force is sufficient to overcome the magnetic attraction of the magnetized plastic sheets 91c, 92c to the core 94, causing the inserts 81, which are now embedded in the box-like cast member, and the assemblies 91 and 92 to be retained as part of the box-like cast member.

When the box-like cast member 93 has been removed from the mold assembly, the interior surface 93a of the cast member has the appearance shown in FIG. 8B with the planar surfaces of the sheets 91c and 92c being exposed, as shown. The assemblies 91 and 92 are partially embedded within the surface 93a of the box-like cast member 93. The assemblies 91 and 92 are then pried away from the surface 93a of the cast member 93. FIG. 8C shows one of the assemblies 91 partially pried away from interior surface 93a. Through the use of a suitable tool (not shown) the assembly 91 is pried away from surface 93a, the pins 91b being released from the inserts. The inserts remain embedded within the cast material and are retained embedded in the cast material by virtue of the external flanges 81d arranged at spaced intervals about the exterior of each insert.

FIG. 8D shows a view of the interior surface 93a of the cast member 93 the inserts, identified generically as “I” have their open ends open to the interior of the cast member 93 and are ready to receive step members. The recesses R have a depth substantially equal to the thickness of the assemblies 91, 92.

FIG. 8E shows a plurality of step members S having their outwardly extending legs Sa, Sb force-fittingly inserted into the open ends of the inserts I, thus completing the provision of manhole type steps within the cast member according to the present invention.

FIG. 8F shows an arrangement similar to that of FIG. 8D wherein the member to be cast is further provided with a reinforcing structure formed of a plurality of horizontally aligned and vertically aligned bars, such as I-bars B, to provide the cast member with additional structural strength. The manner in which the assemblies 91 and 92 are utilized is substantially the same as described hereinabove in connection with FIGS. 8-8E.

As a further alternative embodiment, in applications where the members making up the mold assemblies are formed of a material other than a ferro-magnetic material such as aluminum, wood, etc., the arrangement shown in FIGS. 9 and 9A is employed wherein suitable magnets 99 and 100 are positioned along the hollow interior surface of core member 94 and aligned so as to magnetically attract the assemblies 91, 92 when they are properly aligned. The manner in which the assemblies 91 and 92 and templates 95 and 96 are employed is substantially identical to that described above in connection with the assembly shown in FIGS. 8-8E, except that the magnetized members are arranged along the interior wall of the core 94 to magnetically attract the assemblies 91, 92, 95 and 96, which are formed of a ferromagnetic material, and hold them against the surface 94a. The assemblies 91′ and 92′ differ from the assemblies 91 and 92 described above in that the plastic sheets containing the ferro-magnetic particles may be omitted whereby the assemblies 91′, 92′, formed of a suitable ferro-magnetic material, are magnetically attracted to the magnets 99, 100. Alternatively, magnets 99, 100 may preferably comprise a plurality of permanent magnets arranged along the interior of the core member 94. The templates 95′ and 96′ may likewise have the plastic sheets 97, 98 impregnated with ferro-magnetic materials omitted. The permanent magnets 99, 100 are preferably of a width or extend to a width greater than the width of the strips 91′, 92′ so that their interior edges extend beyond the interior edges of the assemblies 91′, 92′ so as to cause the left-hand and right-hand ends of the templates 95′, 96′ to be magnetically attracted to the permanent magnets 99, 100.

As was described hereinabove, the templates 95′, 96′ are preferably removed before the cast material is poured into the mold assembly.

When the cast material has been set, it is separated from core 94. The force exerted in separating the cast member from the core 94 is sufficient to overcome the magnetic attraction between permanent magnets 99, 100 and the assemblies 91′, 92′ whereby the inserts I and hence the assemblies 91′, 92′ are retained by the cast member and are subsequently pried away from the cast member in the same manner described above, making reference to FIG. 8C.

The assemblies 91′, 92′, templates 95′, 96′, as well as the assemblies 91, 92 and templates 95 and 96 are sufficiently sturdy so as to provide repeated use over a long useful operating life.

As a further alternative, a suitable adhesive or glue may be placed upon the rear surface of each assembly 91′, 92′, which adhesive is sufficient to hold the assemblies in place during the alignment and the molding operations. The adhesive further preferably has limited adhesive holding power so as to enable the templates 95′, 96′ to be removed rather easily prior to filling the mold assembly with cast material and to enable the assemblies 91′, 92′ to be separated from the core member 94 when the cast member is lifted out of the mold assembly, whereupon the final steps of prying the assemblies 91′, 92′ away from the wall 93a of cast member 93 and the insertion of the manhole steps S are performed in the manner described above.

FIG. 8J is a perspective view showing an alternative arrangement for the assemblies 91, 92, 95 and 96 in which permanent magnets are substituted for the plastic sheets 91c, 92c, 95c, 96c impregnated with magnetized ferromagnetic particles. For simplicity, only a portion of one modified strip, 91a, is shown in FIG. 8J, it being understood that the assemblies 92, 95 and 96 may be modified in a manner substantially identical to that shown in FIG. 8J. The surface of strip 91a opposite the surface upon which pins 91b are mounted is provided with pairs of circular recesses 91g, each pair of recesses being arranged at spaced intervals along strip 91a. Disk-shaped permanent magnets 102 are placed in each recess as shown at 102. The surface of strip 91a in which the permanent magnets 102 are mounted is covered with a suitable epoxy 104 to retain the magnets 102 in place. The recesses and permanent magnets may alternatively be any other suitable shape such as rectangular, polygonal and the like and the number and the spacing of the recesses (and magnets) may be selected to assure that the attractive forces provided by the magnets are sufficient for purposes of successfully practicing the method of embedding inserts into a cast member according to the teachings of the present invention. The alternative embodiment of FIG. 8J is employed in the same manner as the strips and templates of FIGS. 8-8E to embed inserts into a cast member. As an alternative to coating the entire surface of strip 91a containing recesses 91g, the recesses are formed to have a depth substantially equal to and preferably slightly greater than the thickness of the permanent magnets 102 so that the top surface 102a of each permanent magnet 102 is substantially flush with the surface in which the recesses are formed, the additional depth of the recesses each accommodating a suitable epoxy applied to occupy the region between the side and bottom surfaces of each recess and the side and bottom surfaces of the magnets inserted into each recess.

A latitude of modification, change and substitution is intended in the foregoing disclosure, and in some instances, some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein described.