FOUNDRY FLASK GUIDE APPARATUS
United States Patent 3645324
A guide pin and bushing assembly for use in the alignment of the cope and drag of a foundry flask or core box wherein the bushing is reversible and is formed with two external annular grooves and carries a resilient retaining ring in one of said grooves. As the bushing becomes worn at one end on its interior through repeated frictional contact with the guide pin, it can be reversed to use the other end by removal of the retaining ring and replacing the ring in the other annular groove. This effectively doubles the useful life of the bushing.
International Harvester Company (Chicago, IL)
B22C21/10; (IPC1-7): B22C21/10
Field of Search:
Baldwin, Robert D.
1. A pin and bushing assembly for use in the alignment of the cope and drag sections of a foundry flask or core box and the like, each of said core and drag sections having a lateral edge flange with at least one of said lateral edge flanges having a cylindrical bore formed therethrough with one end thereof opening into a cylindrical recess of a larger diameter than said bore, said recess being formed in a substantially flat surface area portion of said lateral edge flange and partially defining an annular surface spaced and substantially parallel with respect to said flat surface area portion, comprising, a guide pin secured to a respective one of said lateral edge flanges and projecting substantially normally from one side thereof, said guide pin having an external guide surface formed thereon; a selectively reversible guide bushing removably carried by the other respective one of said lateral edge flanges, said guide bushing having a central axially extending opening therethrough, axially spaced end surface portions of the surface defining said opening serving as internal guide surfaces, either end of said bushing being selectively insertable into said cylindrical bore a predetermined distance to dispose either one of said internal guide surfaces in a pin-receiving position so as to be capable of individually slidingly receiving said external guide surface of said guide pin and to simultaneously dispose the other internal guide surface in a position wherein it is incapable of slidingly receiving said external guide surface of said guide pin; abutment means carried by said bushing and operably engageable with said annular surface to limit the distance said bushing is insertable into said cylindrical bore so as to dispose a respective one of said internal guide surfaces in a pin-receiving position; and means for releasably securing said abutment means to said bushing at either one of two spaced positions along the longitudinal axis of said bushing so as to permit adjustment of said abutment means with respect to said bushing and to thereby selectively dispose either one of said internal guide surfaces in its pin-receiving position when said abutment means is in operable engagement with said annular surface.
2. A pin and bushing assembly as set forth in claim 1, wherein said bushing has a generally cylindrical external surface, and said abutment means includes an annular portion extending generally radially outwardly from said external cylindrical surface of said bushing, said annular portion being abuttable against said annular surface of said one lateral edge flange to establish said pin-receiving positions of said internal guide surfaces.
3. A pin and bushing assembly as set forth in claim 2, wherein said bushing cylindrical external surface is formed with a pair of axially spaced annular grooves therein, each of said grooves being spaced closely adjacent a respective end of said bushing, said abutment means being receivable in either of said annular grooves so as to be axially fixed with respect to said bushing.
4. A pin and bushing assembly as set forth in claim 3, wherein said abutment means is in the form of a detachable retaining ring, said ring being radially contractable to frictionally grip said bushing when disposed in either of said grooves, said ring including biasing means yieldably and radially contracting said ring.
5. A pin and bushing assembly as set forth in claim 4, wherein the cylindrical section of said bushing located between said grooves has a larger diameter than the diameters of the cylindrical end sections of said bushing.
6. A pin and bushing assembly as set forth in claim 5, wherein said external guide surface of said guide pin is substantially cylindrical in shape, and wherein said opening extending through said bushing is in the form of a generally cylindrical bore and said internal guide surfaces of said bushing are substantially cylindrical in shape.
7. A pin and bushing assembly as set forth in claim 6, wherein each end of said cylindrical bore is defined by an annular, outwardly tapering section to facilitate insertion of said guide pin therein.
8. A pin and bushing assembly as set forth in claim 5, wherein said internal guide surfaces of said bushing are substantially ovate in shape, and the cross sectional area of said guide pin through said external guide surface thereof is substantially ovate in shape.
BACKGROUND OF THE INVENTION
This invention relates to Metal Founding and more particularly to plural part flasks or flask sections, including guide means to align superposed flask sections.
In modern foundry practice, a plurality of flasks or core boxes are used to form molded metal products from molten metal. Such flasks normally are made of two parts, a cope and a drag, with guide pins and bushings located around the periphery of each to ensure proper alignment when the two parts are brought together. Such pins and bushings normally are retained or positioned within cylindrical bores formed in flanges integral with the cope and drag. The guide pins normally comprise a cylindrical body formed with an integral enlarged collar or stop for locating the pin in its proper position in the flange. The bushing normally is in the form of a cylindrical sleeve and has an integral enlarged external collar. The collar serves as a stop for locating the bushing in its proper position with respect to its flange.
When the cope and drag are brought together prior to filling with molten metal, the guide pins enter the central bores of the bushings and form a close fit so as to ensure proper alignment of the cope and drag. Through repeated use, the frictional contact of the guide pins with the interior surfaces of the bushings produce wear to an extent that misalignment beyond tolerable limits can occur.
SUMMARY OF THE INVENTION
The present invention provides an improved guide pin and bushing assembly that has a useful life that is practically double that of the conventional assembly. In particular, the guide bushing is designed so as to be reversible as one end becomes worn on its interior and thereby effectively provide the equivalent of a new bushing.
The bushing of the present invention is not formed with an enlarged external collar. Rather, the bushing is in the form of a cylindrical sleeve. This permits the bushing to be machined from tube stock that has an initial diameter that is smaller than is required for the conventional bushings.
The bushing of the present invention is formed with two external annular grooves spaced substantially equidistant from the ends of the bushing. A resilient retaining ring is mounted in one of the grooves and it serves as a stop member or positioning means; that is, to perform the same function as the enlarged cylindrical collar of the conventional bushing. As this improved bushing becomes worn on its internal surface through use, it is merely removed from its mounting bore, the retaining ring removed from one groove and replaced in the other groove. The bushing is then turned end for end and replaced in its mounting bore. This presents a new wear surface for contact with the guide pin.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the guide pin and bushing assembly of the present invention as located in its proper position with respect to the cope and drag sections of a foundry flask;
FIG. 2 is an exploded view of the components of the pin and bushing assembly of FIG. 1;
FIG. 3 is an end view, taken on line 3--3 of FIG. 2, of the bushing of FIG. 2;
FIG. 4 is an end view of a modified form of bushing having an ovate interior;
FIG. 5 is an elevation view in section of the improved pin and bushing assembly of the present invention;
FIG. 6 is an elevation view, partly in section of a prior art pin and bushing assembly; and
FIG. 7 is an elevation view of the bushing of FIG. 6 showing areas of wear on its interior surface.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The pin and bushing assembly of the present invention is designated generally by the numeral 10 and comprises a cylindrical guide bushing 11, a guide or stub pin 12, and a split retaining ring or abutment 13. A plurality of such assemblies are incorporated in a foundry flask to ensure precise registry of the cope and drag sections of the flask.
Referring to FIG. 1, a fragmentary view of a foundry flask or core box 20 is shown and comprises a cope 21 and drag 22. The cope 21 has a lateral edge flange 23 and the drag 22 has a parallel facing edge flange 24. The flange 23 is formed with a cylindrical bore 25 for receiving the bushing 11, and the flange 24 is formed with a cylindrical bore 26 for receiving the stub pin 12.
Referring now to FIG. 2, the bushing 11 is formed of steel and is seen to have an internal cylindrical bore 30 and external cylindrical surfaces 31, 32, and 33 separated by annular grooves 34 and 35. The ends of the bore 30 taper outwardly at 36 and 37 to facilitate entry of the stub pin 12 into the bore 30. The diameter of the middle cylindrical outer surface 31 is slightly larger than the diameters of the end cylindrical surfaces 32 and 33 by a few thousandths of an inch. This is to facilitate the mounting of the retaining ring or abutment 13 in the grooves 34 and 35, These grooves are cu by a machining process to the proper width and depth to receive closely a ring or abutment 13 of given predetermined dimensions. The ring or abutment 13 is made of spring steel and preferably is of the "Spirolox" type.
The stub pin 12 is generally in the form of a cylindrical sleeve and has a central bore 40 and outer cylindrical surfaces 41 and 42. The outer cylindrical surfaces 41 and 42 are separated by a collar 43 of somewhat larger diameter. The outer ends of the pin 2 are beveled at 44 and 45 to facilitate entry into the bore 26 and 30. The bore 26 is formed with an enlarged cylindrical recess 46 for receiving the collar 43.
Referring now to FIG. 6, there is illustrated a conventional stub pin 12 and conventional bushing 11A, a type well known in the art. The bushing 11A is formed at one end with an integral enlarged cylindrical collar 11B. The bore 25 in the cope 23 is formed with an enlarged cylindrical recess 27 for receiving the collar 11B.
In normal operation, the cope 23 and drag 24 are repeatedly separated to allow removal of a cast article and brought together again for refilling with molten metal. To ensure that the article cast is uniform from one molding cycle to the next, it is important that the cope 23 and drag 24 be in exact registry each time. The entry of the stub pin 12 into the bore 30A of the conventional bushing ensures that the cope 23 and drag 24 are properly aligned each time. Through repeated use, the entry of the pin 12 into the bore 30A causes wear on the inner wall of the bore as shown in shaded section 30B in FIG. 7. Eventually, this wear may proceed to the point where misalignment of the cope 23 and drag 24 beyond tolerable limits can occur. The bushing 11A must then be replaced.
The effective life of a bushing can be doubled by introducing the improved bushing 11 of the present invention as shown in FIG. 5. The bushing 11 differs from the bushing 11A in that the collar 11B is eliminated, and the retainer ring 13 is snapped into place in the groove 34. The ring or abutment 13 serves the same function as the collar 11B and it bottoms out within the recess 27 to ensure proper positioning of the bushing 11 within the bore 25.
When wear occurs within the bore 30 of the bushing 11 through repeated use to the point that the bushing must be replaced, it is merely removed from the bore 25, and the retainer ring or abutment 13 is removed from the groove 34 and replaced in the groove 35. The bushing 11 then is turned end for end and replaced in the bore 25. The unused end of the bushing 11 is as good as new, and the effective life of the bushing 11 is therefore doubled. By causing the ring or abutment 13 to bottom out within the recess 27 and abut the annular surface at one end of the bore 30, the unused internal guide surface portion of the bushing 11 is in correct position to receive and properly guide the pin 12.
Referring now to FIGS. 3 and 4, there is shown an end view of the bushing 11 and of an alternate form of bushing 11'. The bushing 11 has been described as having a cylindrical central bore 30. As can be seen from FIG. 4, the bushing 11' may have an ovate interior 30', or other shape for that matter, as long as mating stub pins of the same cross sectional dimensions are provided. The principle of the present invention that allows the doubling of the useful life of the bushing 11 still prevails.
The invention shown and described is by way of example only and is not to be considered as limited thereto, except insofar as the claims may be so limited. It is to be understood that modifications may be made thereto without departing from the spirit of the invention.