GB2253801A - Support for holding work pieces and forming process thereof - Google Patents

Abstract

The support (10) for holding a work piece (23) comprises a base (11) and a holder (12) e.g. of silicone rubber which is moulded in or on the base (11) to form a recess (22) that is of such a shape as to receive and hold the work piece (23) in place. A two-part mould comprising two such bases (11) is assembled, with an internal cavity and containing a PCB. Holder material is introduced into the mould in order, by moulding operation, to form a recess (22) of such a shape as to receive and hold the work piece (23) in place. The upper base part (11) of the mould is removed, thereby leaving the holder (12) in or on the other part (11) of the mould to form the support (10). <IMAGE>

Description

SUPPORT FOR HOLDING WORK PIECES AND FORMING PROCESS THEREOF The invention relates to a support for holding work pieces, such as but not exclusively electronic component boards or the like, and to a process of forming such a support.

It is often necessary to hold a work piece in position for operations to be performed thereon. Holders or supports for that purpose are known. In relation to electronic component boards, for example, aluminium supports are used which are typically aluminium plates having recesses machined, such as by milling, therein for receiving and thereby holding the boards in place. The recesses are normally milled to substantially the shape of the boards, and operations such as placing electronic components thereon or soldering so placed electronic components to the boards can be performed.

It will be appreciated that the making of such supports are expensive and time consuming, particularly where the design of work pieces changes too frequently.

The invention aims to mitigate or alleviate such disadvantages of existing supports.

According to a first aspect of the invention, there is provided a support for holding a work piece, which support comprises a base and a holder which is moulded in or on the base and to form a recess that is of such a shape as to receive and hold a said work piece in place.

Preferably, the holder is moulded to form the recess to that shape by using a moulding piece to provide part of the moulding surface against which the holder is moulded.

It is preferred that the recess has a shape corresponding substantially to that of a said work piece.

Advantageously, a said work piece is used as the moulding piece.

In a preferred embodiment, the holder is moulded by introducing the appropriate holder material into a moulding cavity formed by placing together two said bases against each other.

Preferably, the base has upper and lower surfaces, on or in which upper surface the holder is moulded and on which lower surface a pattern is provided for determining the position of the recess to be formed.

It is preferred that the holder is moulded from silicone rubber.

In a preferred embodiment, the support is provided for holding an electronic component board or boards.

According to a second aspect of the invention, there is provided a process of forming a support for holding a work piece, which process comprises providing a two-part mould, introducing a material into the mould in order to form a work piece holder by moulding operation, which holder is to be moulded to form a recess of such a shape as to receive and hold a said work piece in place, and removing one part of the mould, thereby leaving the holder in or on the other part of the mould to form the support.

In a preferred embodiment, the mould has two substantially the same parts each having a hole, and the process comprises placing more than two said parts one against the next other so as to form a series of moulding cavities which are in communication through the holes, and introducing the holder material into the cavities successively through the holes.

Preferably, the process further comprises fixing a moulding piece on the inner surface of the said one part of the mould so that the recess will be formed substantially to the shape of the moulding piece.

Advantageously, a said work piece is used as the moulding piece.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of an embodiment of a support in accordance with the invention; Figure 2 is a plan view of a base of the support of Figure 1; Figure 3 is an underneath plan view of the base of Figure 2; and Figure 4 is a partial sectional side view of two bases of Figures 2 and 3.

Referring to the Figures 1 to 3 of the drawings, there is shown an embodiment of a support 10 according to the invention, which support 10 comprises a base 11 and a holder mat 12 therein. The base 11 has a shape resembling that of a square tray, and is formed of ABS by injection moulding. A bottom wall 13 of the base 11 has a ribbing grid pattern 14 on its upper side and a comparatively much finer grooved grid pattern 15 in its lower side. A central and four corner holes 16 are formed in the bottom wall 13.

The base 11 has two pairs of opposed, outwardly extending rims 17a and 17b, and a central hole 18 and two recesses 19 on opposite sides of the central hole 18 are formed in each rim 17a. Directly below each recess 19, on the under side of the corresponding rim 17a, there is provided a co-axial peg 20 whose diameter is slightly smaller than that of the recess 19 above it.

Referring also to Figure 4, when an identical base 11' (having like parts designated by like reference numerals with apostrophes) and the base 11 are placed one squarely upon the other, the pegs 20' are received in the corresponding recesses 19 so that the bases 11' and 11 are prevented from moving apart sideways. Each said base is designed so that it can be completely closed by another base placed thereupon as described above, forming therebetween a cavity 21 in which the holder mat 12 is moulded into shape.

The holder mat 12 is moulded from silicone rubber, and to form a recess 22 having such a shape as to receive and thereby hold a work piece 23 which in this particular embodiment is a blank electronic component board. In order to form the recess 22, a spare electronic component board 23' which serves as a moulding piece is firstly glued on the lower side of the bottom wall 13' of the base 11' at a position determined with reference to the grooved grid pattern 15'.

After the two bases 11 and 11' have been placed together, thereby forming a mould, as described above, silicone rubber paste is then injected into the cavity 21 through one of the holes 16', preferably the central one, of the base 11' while the holes 16 of the bottom base 11 are sealed until the cavity 21 is fully occupied, and this happens usually when the silicone rubber paste overthrows through all the corner holes 16' of the upper base 11'.

When the silicone rubber has become harden, the upper base 11' is removed, and the silicone rubber holder mat 12 is left in the lower base 11, together forming the support 10.

The ribbing grid pattern 14 serves to assist retaining the holder mat 12 within the base 11 both during and after removal of the upper base 11'.

The design of the base 11 permits several supports 10 to be formed simultaneously. This is done by stacking several (the number of supports to be formed plus one) bases 11 together, in the same manner as described above, and injecting silicone rubber paste through the central hole 16 of the uppermost base 11. The silicone rubber paste will travel down the stack and eventually fill up all the cavities 21 successively.

As soon as the supports 10 are formed, each electronic component board (moulding piece) 23 fixed on the bottom side of the corresponding next upper base 11 can be removed except the one fixed underneath the uppermost base 11 which can be used again as it does not form a complete support.

The manner described above of forming the recess 22 by using an actual electronic component board 23 to provide part of the moulding surface is the simplest and most convenient method. An alternative is to use a model of the electronic component board 23 as a moulding piece, and advantageously such a moulding piece can be made slightly smaller so as to enhance the gripping of the actual work piece by the recess 22 by virtue of the resilience of silicone rubber. A further alternative is to use a moulding piece 24 which does not have a shape corresponding to that of the actual work piece to be held, by means of that the resulting recess will form some gaps 25 between the peripheries of the recess and the work piece placed therein to facilitate removal of the work piece after the appropriate operations have been performed.

It is understood that precise positioning of the work piece or moulding piece to be fixed underneath the upper or the next upper base is preferred for subsequent fully automatic operations to be performed by an automatic machine on the work piece held by the support 10. This is because such precise positioning provides an accurate positioning of the resulting recess 22 and in turn the work piece 23 located therein relative to the base 11 whose position can serve as a reference for the automatic machine, such as a pick-andplace machine or chip mounter, to reach the work piece.

The invention has been described by way of example only, and various other modifications of and/or alterations to the described embodiment may be made by persons skilled in the relevant art without departing from the scope of the invention as specified in the appended claims.

Claims (14)

1. A support for holding a work piece, which support comprises a base and a holder which is moulded in or on the base and to form a recess that is of such a shape as to receive and hold a said work piece in place.

2. A support as claimed in claim 1, wherein the holder is moulded to provide the recess to that shape by using a moulding piece to provide part of the moulding surface against which the holder is moulded.

3. A support as claimed in claim 1 or claim 2, wherein the recess has a shape corresponding substantially to that of a said work piece.

4. A support as claimed in claim 2 or claim 3, wherein a said work piece is used as the moulding piece.

5. A support as claimed in any one of claims 1 to 4, wherein the holder is moulded by introducing the appropriate holder material into a moulding cavity formed by placing together two said bases against each other.

6. A support as claimed in claim 5, wherein the base has upper and lower surfaces, on or in which upper surface the holder is moulded and on which lower surface a pattern is provided for determining the position of the recess to be formed.

7. A support as claimed in any one of the preceding claims, wherein the holder is moulded from silicone rubber.

8. A support as claimed in any one of the preceding claims, which is provided for holding an electronic component board or boards.

9. A support substantially as hereinbefore described with reference to the accompanying drawings.

10. A process of forming a support for holding a work piece, which process comprises providing a two-part mould, introducing a material into the mould in order to form a work piece holder by moulding operation, which holder is to be moulded to form a recess of such a shape as to receive and hold a said work piece in place, and removing one part of the mould, thereby leaving the holder in or on the other part of the mould to form the support.

11. A process as claimed in claim 10, wherein the mould has two substantially the same parts each having a hole, and the process comprises placing more than two said parts one against the next other so as to form a series of moulding cavities which are in communication through the holes, and introducing the holder material into the cavities successively through the holes.

12. A process as claimed in claim 10 or claim 11, further comprising fixing a moulding piece on the inner surface of the said one part of the mould so that the recess will be formed substantially to the shape of the moulding piece.

13. A process as claimed in claim 12, wherein a said work piece is used as the moulding piece.

14. A process of forming a support for holding a work piece, substantially as hereinbefore described with reference to the accompanying drawings.