Title:
REINFORCING STRUCTURE FOR PLASTIC LID
Kind Code:
A1


Abstract:
A plastic closing lid for a storage container, the closing lid having a length dimension and a shorter width dimension. The lid defining a receiving channel extending lengthwise and a stiffening component captured within said receiving channel.



Inventors:
Orr, Kenneth Lewis (Indianapolis, IN, US)
Application Number:
12/029110
Publication Date:
08/14/2008
Filing Date:
02/11/2008
Primary Class:
Other Classes:
220/780
International Classes:
B65D41/16; B65D41/02
View Patent Images:
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Primary Examiner:
MCKINLEY, CHRISTOPHER BRIAN
Attorney, Agent or Firm:
Greatbatch Ltd. (Clarence, NY, US)
Claims:
1. In combination: elongate, lid-stiffening member; and a plastic lid for a storage tray, said plastic lid having a length dimension and a shorter width dimension and being constructed and arranged with an elongate rib defining an interior channel, said interior channel being constructed and arranged for receiving said lid-stiffening member.

2. The combination of claim 1 wherein said plastic lid including a tray-facing surface and opposite thereto an outer surface, said elongate rib being constructed and arranged in a raised configuration so as to extend above an adjacent portion of said outer surface.

3. The combination of claim 2 wherein said lid-stiffening member is generally cylindrical and said interior channel is part-cylindrical.

4. The combination of claim 3 wherein said interior channel includes a channel opening that is defined by a pair of spaced-apart, facing rib edges.

5. The combination of claim 4 wherein said generally cylindrical, lid-stiffening member includes a diameter dimension and said facing rib edges have a distance of separation that is smaller than said diameter dimension.

6. The combination of claim 5 wherein said generally cylindrical, lid-stiffening member is a metal tube.

7. The combination of claim 4 wherein said channel opening opens in a downward direction adjacent said tray-facing surface.

8. The combination of claim 4 wherein said channel opening opens in an upward direction away from said outer surface.

9. The combination of claim 1 wherein said plastic lid includes a tray-facing surface and opposite thereto an outer surface, said elongate rib being constructed and arranged in a raised configuration so as to extend beyond an adjacent portion of said tray-facing surface.

10. The combination of claim 9 wherein said lid-stiffening member is generally cylindrical and said interior channel is part-cylindrical.

11. The combination of claim 10 wherein said interior channel includes a channel opening that is defined by a pair of spaced-apart, facing rib edges.

12. The combination of claim 11 wherein said generally cylindrical, lid-stiffening member includes a diameter dimension and said facing rib edges have a distance of separation that is smaller than said diameter dimension.

13. The combination of claim 12 wherein said generally cylindrical, lid-stiffening member is a metal tube.

14. The combination of claim 1 wherein said elongate rib extends in a direction that is generally parallel to said length dimension.

15. The combination of claim 14 which further includes: second, elongate, lid-stiffening member; and a second, elongate rib that is spaced-apart from said first elongate rib, said second elongate rib defining an interior channel that is constructed and arranged for receiving said second, elongate, lid-stiffening member.

16. The combination of claim 15 wherein said first and second elongate ribs are substantially parallel to each other.

17. The combination of claim 16 wherein said first and second lid-stiffening member are each generally cylindrical and wherein each interior channel is part-cylindrical.

18. The combination of claim 17 wherein each interior channel includes a channel opening that is defined by a pair of spaced-apart, facing rib edges.

19. The combination of claim 18 wherein said each lid-stiffening member includes a diameter dimension and each pair of facing rib edges have a distance of separation that is smaller than each of said diameter dimensions.

20. In combination: an insertable, lid-stiffening component; and a plastic lid for a storage tray, said plastic lid being constructed and arranged with a plurality of rib sections, said plurality of rib sections being positioned in different locations on said lid and extending in different directions, at least one rib section of said plurality of rib sections defining an interior channel and said lid-stiffening component being constructed and arranged to be manually inserted into the interior channel of said at least one rib section for adding stiffening to said plastic lid.

21. The combination of claim 20 wherein said plastic lid includes a tray-facing surface and opposite thereto an outer surface, said at least one rib section being constructed and arranged in a raised configuration so as to extend above an adjacent portion of said outer surface.

22. The combination of claim 21 wherein said lid-stiffening component is generally cylindrical and said interior channel is part-cylindrical.

23. The combination of claim 22 wherein said interior channel includes a channel opening that is defined by a pair of spaced-apart, facing rib edges.

24. The combination of claim 23 wherein said lid-stiffening component includes a diameter dimension and said facing rib edges have a distance of separation that is smaller than said diameter dimension.

25. The combination of claim 20 wherein said plastic lid having a length dimension and a shorter width dimension and wherein said at least one rib section extends in a direction that is generally parallel to said length dimension.

26. The combination of claim 25 which further includes: a second, insertable, lid-stiffening component; and a second rib section that is spaced-apart from said at least one rib section, said second rib section defining an interior channel that is constructed and arranged for receiving said second, insertable, lid-stiffening component.

27. The combination of claim 26 wherein said at least one rib section and second rib section are substantially parallel to each other.

28. A lid assembly for a storage tray comprising: a plastic lid body having a length dimension and a shorter width dimension; and a lid-stiffening component that is insert-molded into said lid body.

29. The lid assembly of claim 28 wherein said lid-stiffening component is constructed and arranged so as to extend in a direction that is substantially parallel with said length dimension.

30. The lid assembly of claim 29 wherein a second lid-stiffening component is insert-molded into said lid body.

31. The lid assembly of claim 30 wherein said second lid-stiffening component is substantially parallel with said first lid-stiffening component.

32. The lid assembly of claim 31 wherein each lid-stiffening component is a metal tube.

Description:

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a Continuation-in-Part of and claims the benefit of U.S. Provisional Patent Application Ser. No. 60/900,907, filed Feb. 12, 2007, entitled “REINFORCING STRUCTURE FOR PLASTIC LID” which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Storage containers for the containment of discrete articles, such as medical devices, equipment and instruments typically include a storage tray and closing lid combination. Typical materials for either the tray or the lid or both include steel, aluminum, other metals, and plastics. Size variations, whether in length, width or depth, are also common for these types of storage containers.

One concern that has been recognized is the flexible nature of plastic closing lids when the longer dimension (length) reaches a certain size, depending on the material, material thickness, and other design variables. This lid flexibility can be influenced to some extent on the plastic selected for the molding or forming process as well as the material thickness that is molded or formed. Other influencing factors include the length dimension and the presence or absence of stiffening ribs, bosses, channels, etc., that are part of the unitary lid construction and that might be able to provide some degree of stiffening or reinforcing to the lid, adding to its rigidity. For the most part, these added forms need to run length-wise with a sufficient length to actually add to the stiffness of the lid and reduce or lessen its flexibility. Handling of the closing lid and assembly of the lid onto the tray are facilitated by added lid stiffening or rigidity. There may also be a customer benefit in terms of the overall product construction not appearing to be cheap or flimsy. As used herein “reinforcing” of the closing lid is achieved by adding a stiffening component to increase the rigidity.

Perhaps a less intuitive aspect of having a flexible closing lid as one portion of a storage container is the number of slide latches (as one example of the type that can be used) that is required for securely connecting or attaching the closing lid to the tray. When the closing lid is constructed of a size, shape, and material that results in overall lid flexibility, it is likely that four slide latches will be used. There is typically a slide latch on each end and a slide latch on each side. While the reference herein is made to a slide latch, it should be understood that any type of latching or closing mechanism should be suitable at those four spaced-apart locations. By reinforcing the closing lid according to the present disclosure, it is envisioned that only two oppositely-disposed latches would be required to properly secure the closing lid to the tray in order to create the desired storage container. The anticipated arrangement when only two latches are used is to position one latch on each side. When tray-lifting handles are provided and are used as lid-latching members, the stiffening members disclosed herein are considered to be sufficient to provide the requisite lid rigidity such that no other latches of any type are needed.

The addition of molded-in or formed-in shapes to the unitary lid construction normally require some amount of added material and this in turn equates to added mold expense. One consideration is the amount of added material that is required to achieve the desired closing lid reinforcement. Another consideration is whether molded-in or formed-in shapes might interfere with any forms that are used for stacking of one container onto another container. Aesthetically, there may be concerns if the top surface of the lid is filled with stiffening forms in lieu of customer decals or labels, for example. Further, once the mold or vacuum-formed tooling is fixed for these stiffening shapes, it is not economical to change or offer design alternatives to customers, particularly to those customers that do not need, want, or want to pay for these lid stiffening features.

The disclosed embodiments address this lid flexibility/lid stiffness issue by capturing a metal or rigid plastic tube or rod in a molded, lengthwise channel or groove, allowing the rigidity of the stiffening component to noticeably reduce the degree of flexibility or flexing of the lid. In order to effectively stiffen the lid, the stiffening component needs to be of adequate length and preferably centered between the ends of the lid. The stiffening component can alternatively be fabricated out of other materials and formed in other shapes. This stiffening component can be mechanically captured by the form or shaping of the channel, or bonded into position with a suitable adhesive, or configured as a molded-in or formed-in insert. A further way of capturing the stiffening component is to lay it in a groove or channel and then enclose the tube with an outer layer or cover. This outer layer or cover can be molded or adhesively bonded or ultrasonically welded into position.

A containment case, as referenced herein, that is suitable for use with the disclosed reinforced plastic lid, is constructed and arranged according to U.S. patent application Ser. No. ______, entitled Containment-Case With Latching Handle, filed (Feb. 11, 2008), and further identified by Attorney Reference 8036-48.

BRIEF SUMMARY

A plastic closing lid for a storage container, the closing lid having a length dimension and a shorter width dimension. The lid defining a receiving channel extending lengthwise and a stiffening component captured within said receiving channel.

One object of the present invention is to provide an improved plastic closing lid. Related objects and advantages will be apparent from the following description.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a plastic closing lid according to the present invention.

FIG. 1A is an end elevational view, in full section, of an integral rib formed lengthwise in the FIG. 1 plastic closing lid and defining a hollow interior channel.

FIG. 1B is an end elevational view corresponding to FIG. 1A with a hollow metal tube installed in the interior channel.

FIG. 2 is a bottom plan view of a generic plastic closing lid showing its inner surface.

FIG. 3 is a partial, bottom plan view of a plastic closing lid showing an alternative embodiment of the present invention.

FIG. 4 is a partial, bottom plan view of a plastic closing lid showing another embodiment of the present invention.

FIG. 5 is a partial, end elevational view of a receiving channel and metal tube combination according to the present invention.

FIG. 5A is a partial, end elevational view of an alternative receiving channel and metal tube combination according to the present invention.

FIG. 5B is a partial, end elevational view of another alternative receiving channel and metal tube combination according to the present invention.

FIG. 6 is a partial, end elevational view of a receiving channel and metal tube combination according to the present invention.

FIG. 6A is a partial, end elevational view of an alternative receiving channel and metal tube combination according to the present invention.

FIG. 6B is a partial, end elevational view of another alternative receiving channel and metal tube combination according to the present invention.

FIG. 7 is a partial, end elevational view of a receiving groove and metal tube combination according to the present invention.

FIG. 7A is a partial, end elevational view of an alternative receiving groove and metal tube combination according to the present invention

FIG. 7B is a partial, end elevational view of another alternative receiving groove and metal tube combination according to the present invention

FIG. 8 is an end elevational view of an enclosing cover suitable for use as part of the present invention.

FIG. 9 is an end elevational view of an alternative enclosing cover suitable for use as part of the present invention.

FIG. 10 is a partial, end elevational view, in full section, of a metal tube captured within a molded plastic lid.

FIG. 11 is a perspective view of a plastic closing lid according to another embodiment of the present invention.

FIG. 12 is a partial, end elevational view, in full section, of the FIG. 11 plastic closing lid with a stiffening tube installed.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated device and its use, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.

Referring to FIG. 1, there is illustrated a unitary plastic closing lid 20, according to the present disclosure, that is constructed and arranged to be applied to a containment tray (not illustrated) for creating a containment case for receiving and storing discrete articles, typically medical (or dental) equipment, devices, and/or instruments. Prior art versions of lid 20 typically include areas for receiving cooperating slide latches (not illustrated), preferably one on each side or end, that are used to secure the closing lid to the tray. Based on the use of stiffening members for reinforcing lid 20, it is possible to reduce the four latches to two, likely located along the sides near areas 21. When the lifting handles are used to latch the lid, it is possible to eliminate all four slide latches, due to the use of stiffening members. Lid 20 also includes a plurality of spaced-apart openings 22 for the flow of steam (or sterilant) into and out of the case.

One characteristic of plastic closing lids of the type generally illustrated herein is the flexibility of the lid due to its size and material. Depending on the length (L) and width (W) dimensions, the material, the material thickness, and any added (molded) forms for stiffening, the typical plastic lid will exhibit some degree of flexibility. In terms of handling, assembly to or removal from the tray, and overall customer impressions of product quality, a lid with too much flexibility is not desired. While flexibility is a relative concept, if the lid is too flexible, it will be considered flimsy and not representative of a quality product. Further, if the lid is too flexible, the aforementioned concerns about handling and assembly to or removal from the tray will also be realized. Lids with the typical degree of flexibility would also typically require four latches, such as the referenced slide latches (see the four locations of FIG. 1).

The issue then for the manufacturer of such a plastic lid is how to reinforce the lid by adding rigidity (i.e., stiffening) to the lid in order to reduce the flexibility, without creating other design problems or issues and without significantly adding to the overall cost of the lid. The approach selected, as disclosed herein, is to capture a rigid stiffening component in a molded or vacuum-formed channel or groove or similar receiving recess. Whether the channel or groove or recess is of a continuous length or formed or in a plurality of spaced-apart segments, they are formed as a unitary part of the molded or formed plastic lid. The stiffening component is preferably a metal tube, but alternatively can be fabricated from a rigid plastic or other material and can be a rod or some other shape.

Lid 20 includes a pattern of molded channels, grooves and related forms (raised ribs) extending around the periphery of the lid, across the upper surface of the lid, and around the latching handle areas. The peripheral raised ribs 20a that are adjacent the outer peripheral edge of lid 20 include and define open channels 20b that are formed (i.e., integrally molded) into the raised rib shape that extends above upper surface 20c, as is illustrated in FIGS. 1A and 1B.

FIG. 1A illustrates a cross sectional configuration of one raised rib 20a and its interior open and defined channel 20b. This open interior channel, as formed by rib 20a, extends above upper surface 20c. As will be described in greater detail herein, the open channel interior 20b is sized and shaped to receive a rigid stiffening component.

As noted, lid 20 includes outer raised rib forms, similar to raised rib 20a, specifically raised ribs 20d around the receiving area 20e for a latching handle (not illustrated). These ribs 20d are constructed and arranged to receive properly sized and shaped stiffening members, if that would be desired. However, the maximum benefit from the addition of a stiffening member is a length-wise member that is generally parallel to the length dimension “L” of lid 20. Four smaller raised ribs 20f are formed in the interior panel portion of lid 20. While these raised ribs 20f could be configured to also receive a smaller diameter stiffening member, it is anticipated that larger stiffening members in the peripheral ribs 20a will add sufficient reinforcement and rigidity to lid 20.

FIG. 1B illustrates the raised peripheral rib 20a with a hollow metal tube 23 snapped into channel 20b. Due to the forming and spacing of edges 20g in the manner illustrated, clearance opening 20h has a width dimension that is smaller than the diameter of hollow metal tube 23. Accordingly, the assembly of tube 23 into channel 20b is accomplished by forcing tube 23 through opening 20h such that the tube 23 snaps into the channel 20b.

Referring to FIG. 2, the inner surface 25 of an alternative lid 24 is illustrated and includes, as part of its unitary construction, two substantially parallel molded-in (or vacuum formed) channels 26 and 27. In terms of “inner” and “outer” as used herein, an “inner” surface of the lid is the surface that faces the interior of the containment case, toward the instruments and/or devices, equipment, etc. These two channels extend along the length dimension (L) and are substantially parallel to the longitudinal centerline 28. Preferably, each channel extends for at least forty percent (40%) of the “L” dimension. The FIG. 2 illustration shows each channel 26 and 27 as a raised form (inwardly directed), similar to what is shown as a cross section in FIGS. 5 and 6, with a hollow metal tube 29 installed, as one example. Each raised channel 26 and 27 can also be arranged in spaced-apart sections or segments 30, as illustrated in FIG. 4. The FIG. 2 channels are assigned reference numerals 26 and 27 to represent a general or generic form. The specific channel constructions of FIGS. 5 and 6 are given distinguishing letters a and b, respectively. Further variations are illustrated in later drawings.

The raised rib construction of lid 20 includes raised forms that are predominantly above upper surface 20c. These rib forms are illustrated in FIGS. 5B, 6B, and 7B. In FIG. 2, the rib construction of lid 24 includes forms extending inwardly from inner surface 31. These rib forms are illustrated in FIGS. 5, 6 and 7. A third variation, something that is actually in between these two other configurations, is also possible and is illustrated in FIGS. 5A, 6A and 7A.

With continued reference to FIG. 2, centered on centerline 28 in broken line form is an optional third channel 33. If additional stiffening or reinforcement is desired for lid rigidity, this third channel 33 can be added as a complement to channels 26 and 27. Each channel is constructed and arranged to receive a stiffening member, which is preferably hollow metal tube 29. Other options include a metal rod, a rigid plastic tube, a rigid plastic rod and other cross section shapes, such as square, rectangular, triangular, for example, in either metal or rigid plastic. One form for each raised channel 26 and 27 is illustrated in FIG. 5, specifically identified as 26a, wherein raised portions 34 and 35 are substantially parallel, straight walls that are spaced apart a dimension that is only slightly larger than the diameter of tube 29. This construction requires the use of an adhesive to hold the tube 29 in place or alternatively some form of enclosing cap 43, 44 or structure, see FIGS. 8, 9, and 10. The same sidewall construction of raised portions 34 and 35 can be used for the spaced-apart segments 30.

One option for the forms of FIGS. 5, 6, and 7 that include raised portions 34, 35, 36, and 37, and a recess (concave) shape such as groove 41, is to form the outer or upper surface of lid 20 (or lid 42 in the case of FIG. 7) with a complementing shape (see FIGS. 5A, 6A and 7A, respectively. This added forming or shaping contributes to the overall reinforcement or stiffening of the lid and additionally results in having slightly greater clearance on the interior of the containment case. In FIG. 5A, rib 34a spans the spacing of portions 34 and 35 so that tube 29 (the stiffening member) seats deeper into the body of the lid 20. A similar arrangement and result is achieved by rib 36a in FIG. 6A and by rib 41a in FIG. 7A. Another option, as illustrated in the preferred embodiments of FIGS. 1A and 1B, is to form all of the rib structure on the upper, outer surface of the lid, see also FIGS. 5B, 6B and 7B.

Referring to FIG. 6, the sidewall portions 36 and 37 of channel 26b are higher and are curved, as compared to portions 34 and 35. If channel 27b was illustrated, it would have the same construction as channel 26b. The curvature of each portion 36 and 37 creates a generally circular (in lateral cross section) space for receipt of tube 29. The edge-to-edge separation that defines gap 38 is smaller than the diameter of tube 29. As a result, when tube 29 is assembled into this channel form, the tube has to be forced through gap 38, something which is permitted by the flexing and separation of portions 36 and 37. The resiliency of this molded plastic construction provides a type of spring back with regard to portions 36 and 37, thereby causing the tube 29 to be captured and securely retained in its corresponding channel 26b (and 27b). The same is achieved by the FIG. 6A construction. The FIG. 6 style of channel can be used for the spaced-apart segments 30. While the use of adhesive is not required for the FIG. 6 construction, adhesive can be used for added security and the capture of tube 29. While the use of a hollow metal tube is illustrated, any of the other shapes and materials previously listed are suitable for the referenced stiffening member or component.

Referring now to FIG. 3, the channel construction of lid 20 is replaced by a recessed groove 41 as part of the construction of plastic closing lid 42. It is to be understood that lid 42 is identical to lid 20, except that the raised channel construction of channels 26 and 27, and possibly channel 33, including the various forms of these channels based upon FIGS. 5, 6, and 4 is replaced with a recessed groove 41. A second groove (although not illustrated) is used in the location of channel 27 and a third groove is an option and would be located generally in the same location as optional channel 33. Groove 41 is illustrated in FIG. 7 with tube 29 place therein. All of the grooves, channels and forms incorporated as part of the unitary lids 20 and 42 extend for at least forty percent (40%) of the “L” dimension. In the case of any segments or sections such as segments 30, the combined length is at least forty percent of the “1” dimension.

Since tube 29 cannot be captured by groove 41, so as to remain within groove 41 in a securely retained condition, either an adhesive must be used or some type of capturing cover, see FIGS. 8 and 9. The capturing covers 43 and 44 can be adhesively bonded in place over tube 29 and groove 41 or the selected cover can be secured in place by ultrasonic welding. Covers 43 and 44 represent only two possibilities and virtually any construction is acceptable so long as tube 29 is securely captured. Covers 43 and 44 can be constructed as either short length segments, using a plurality along the length of the tube 29, or these two covers can be configured as substantially full length sleeves.

A still further option for securely capturing tube 29 is to insert mold the tube 29 in position at the time of molding or forming the corresponding lid 45, noting that lid 45 is otherwise virtually identical to lids 20 and 42. The molded-in insert concept involves positioning the selected tubes 29 in their desired position within the mold or forming tooling and then molding or forming the plastic of the lid around each tube 29.

With regard to the closing lids illustrated in FIGS. 1, 1A, 1B and 2, and depending on the particular edge configuration, something that could change depending on the style of tray, edge periphery channels, or at least channels adjacent the outer edge of the lid, may already exist as part of that lid construction. If such a channel already exists then, in order to practice the present invention, it is necessary to select a properly sized stiffening member, such as a metal tube, and install it. The installation scheme can correspond to any of those illustrated and/or described herein. These options include securing those tubes in position by a snap-fit, by the use of adhesive, or by covering over sufficient portions of the tubes with a plastic cover that would either be adhesively bonded in position or ultrasonically welded, for example.

A still further option would be to place the stiffening tube 29 into a formed corner, most likely formed as a right angle such that the tube 29 would be contacted on two sides 90 degrees apart. This type of interior right angled corner may exist, depending on the form of the lid edge and how it is shaped to attach to the tray. In this construction, those same capturing techniques would be required. Either a snap-fit or the use of an adhesive to secure the tube 29 in position or the use of some covering component that could either be adhesively bonded in position or ultrasonically welded, for example.

Referring now to FIGS. 11 and 12, a reinforced plastic closing lid 50 according to the present invention as illustrated, utilizing two stiffening members in the form of metal tubes installed in opposite length-wise channels formed by defining, raised ribs. Lid 50 is a unitary molded (or vacuumed formed) plastic component that includes a raised rib 51 along side 52 and symmetrically, a second raised rib 53 along the opposite side 54. The illustrated surface 55 is the outer or upper surface of lid 50 and the “raised” form of the two ribs 51 and 53 refers to extending away from surface 55. The raised and part cylindrical form of each rib 51 and 53 creates a corresponding part-circular (in lateral cross section) channel 56 and 57, respectively. Each channel 56 and 57 is constructed and arranged to receive a stiffening member 58 having a shape and material selected from those options already discussed. The edges of ribs 51 and 53 at their junction with the inner face of surface 55 are spaced apart so as to require a snap-fit by the metal tube 58.

Raised ribs 51 and 53 (as well as ribs 50a and 50c) provide some degree of stiffening for the plastic closing lid 50, depending on the size of the ribs, the wall thickness, the type of plastic being used, the length, etc., even without any stiffening component installed into the defined channel. For added stiffening of lid 50, each rib 51 and 53 is arranged and is shaped so as to receive a corresponding stiffening member 58, see FIG. 12. Whether the raised form or structure that defines the open channel that receives the stiffening tube (or rod) extends above the upper surface of the lid or below the inner surface, added lid stiffening is provided in substantially the same way. Similar to what has been described relative to the embodiments of FIGS. 1-10, each stiffening member 58 can be captured within its corresponding channel 56 and 57 (i.e. the open side of each rib 51 and 53, respectively) in a variety of ways. One way is to shape each rib and channel such that gap 59 is smaller than the tube diameter so that the tube must be forced into position and thereafter is retained by the shape of each rib and the more narrow gap 59. Another way to secure the hollow metal tube 58 in the desired position is to use a suitable adhesive. Still another way for securement of the metal tube in position is to insert mold (or form) the hollow metal tube into its corresponding rib. A still further way is to enclose the receiving channel with a cover that can be bonded in place using a suitable adhesive or by ultrasonic welding.

While the preferred embodiment of the invention has been illustrated and described in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that all changes and modifications that come within the spirit of the invention are desired to be protected.