GB2191264A

GB2191264A - Method of forming a resilient unit

Info

Publication number: GB2191264A
Application number: GB08712917A
Authority: GB
Inventors: Alan Salisbury Lamburn
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-06-02
Filing date: 1987-06-02
Publication date: 1987-12-09
Also published as: GB8712917D0; GB8613336D0

Abstract

The method includes forming a tubular outer member 10 from one or more sections 14,15, providing a plurality, e.g. four of rubber elements 12 between an inner member 11 and the outer member 10, and securing the outer member sections 14,15 together by welding. A heat sink such as a cooling liquid (at 18) can be used to prevent damage to the rubber elements resulting from the application of heat used to weld the sections. Instead of welding, adhesive bonding may be used, or the sections may be secured together by clips. <IMAGE>

Description

SPECIFICATION A method of producing a resilient unit and a resilient unit produced by such a method The invention relates to a method of producing a resilient unit of the kind comprising a tubular outer member having a plurality of inner surfaces, a rigid inner member disposed coaxially within the outer member and having a plurality of outer surfaces, and a plurality of pre-compressed resilient elements interposed between the inner and outer members in engagement with said surfaces, the resilient elements being arranged to resist rotation of said inner member relative to said outer member from an undeflected position. Such a unit is hereinafter referred to as a resilient unit of the kind described.

It has long been known that a major problem involved in manufacturing such units is the introduction of the resilient elements, usually lengths of rubber, in a pre-compressed state between the inner and outer members which are normally of elongate form. One method of doing that is described in UK Patent No.

1057103 where the elements are first stressed to reduce their cross-sectiondl size, frozen in the stressed state, inserted between the inner and outer members and then allowed to thaw. However, the elements do not normally freeze very quickly, even in a liquid gas such as liquid nitrogen, and so high speed production of such units by the freezing method is difficult. Also, once frozen, the elements are difficult to handle and rapid installation of the elements between the inner and outer members is most important.

An object of the present invention is to provide an improved method of producing resilient units of the kind described.

According to a first aspect of the invention there is provided a method of producing a resilient unit of the kind described including urging surfaces of the outer member against said resilient elements to compress the elements between the outer and inner members, and securing together portions of the outer member to maintain the resilient elements in the compressed form.

The outer member may comprise a plurality of sections and each of said sections may define a corner for locating one of said resilient elements. Alternatively the outer member may include a single section of material defining corners for locating respective resilient elements and the method may include urging free edges of the section towards each other so as to compress the resilient elements between said section and the inner member, and securing said free edges together.

According to a second aspect of the present invention there is provided a method of producing a resilient unit of the kind described including forming the outer member from a plurality of sections each of which defines at least one corner for locating a respective resilient element, urging the outer member sections towards each other so that the resilient elements are compressed between said sections and the inner member, and securing the said sections together.

According to a third aspect of the invention a method of producing a resilient unit of the kind described includes forming the outer member from at least one section defining corners for locating respective resilient elements, urging free edges of said section towards each other so as to compress said resilient elements between said section and the inner member and securing the edges together.

With such methods, the need for freezing is avoided and the necessary pre-compression of the resilient elements is achieved by urging the sections together.

The sections may be fused together eg by welding or other heat fusion means. In order to reduce the likelihood of the resilient elements from being damaged by the application of heat from the fusion means, the method may include providing heat-sink means adjacent the area to be welded. Such a method may include applying heat-sink components, e.g. copper bars, to the outer member sections assembled with the resilient elements and inner section in a cooling liquid or by immersing the assembly fully in the liquid or positioning portions of the sections to be welded such that the level of the liquid lies between the inner and outer surfaces of said portions.

The method may include effecting relative movement between the heat fusion means, eg a welding head and the outer member assembled with the resilient elements and inner section.

Instead of fixing together the portions/sections of the outer member of said second and third aspects by fusing, a mechanical fixing element could be used.

The mechanical securing element may comprise clip means which engages flanges on the outer member. The clip means may be elongate, e.g. a metal extrusion.

Another method of securing the edges of the sections or section of the outer member may involve bonding.

According to a fourth aspect of the present invention, there is provided a method of producing a resilient unit of the kind described including urging surfaces of the outer member against said resilient elements to compress the resilient elements between the inner and outer members and bonding said outer member in position by adhesive means to maintain the resilient elements in the compressed form.

The method may include forming the outer member from a plurality of sections bonded to each other.

In one embodiment the sections overlap each other and the overlapping sections are bonded together.

In another embodiment the sections may be held together by bonding between said sections and one or more members which may extend across edge portions of adjacent sections of said outer member.

The method may include using an epoxy resin, anaerobic, cyanocrylate or other suitable high integrity adhesive to effect bonding.

The invention also includes a resilient unit made in accordance with any of the aforesaid method aspects.

Resilient units and methods for making the same in accordance with the invention will now be described by way of example with reference to the acompanying drawings in which: Figure 1 is an elevation of a resilient unit of the kind set forth; Figure 2 is a transverse cross-section through one form of a resilient unit in accordance with the invention illustrating a first welding/cooling arrangement; Figure 3 is a view similar to Fig. 2 showing a second welding/cooling arrangement; Figure 4 is a transverse cross-section through a Figure 5 is a transverse cross section through a partly assembled resilient unit having an outer member formed from a single metal sheet.

Figure 6 is a view of part of the fully assembled resilient unit of Fig. 5 provided with a fixing clip.

Figure 7 is a cross-section through a resilient unit in accordance with the invention having outer member sections held together by bonding, and Figures 8 and 9 are cross-sections through alternative outer members of resilient units in accordance with the invention held together by bonding.

In Fig. 1 the known resilient unit has an elongate outer member 10, an elongate inner member 11 and four rubber elements 12 disposed therebetween (two only of which are shown in Fig. 1). The inner member 11 in Fig.

1 is connected to a suspension arm 13 although the present invention is not limited to suspension units. In the remaining figures parts corresponding to parts in Fig. 1 carry the same reference numerals.

In Fig. 2 it can be seen that in accordance with the invention the outer member 10 comprises two U-shaped sections 14,15 each of which defines two corners 16 for locating the four rubber elements 12. To produce the unit two rubber elements 12 are placed in the lower section 15 and the inner member 11 is then placed in position, along with the upper section 14 and remaining rubber elements 12.

Clamping forces F are then applied e.g. by rollers, to the sections 14,15 to urge their adjacent edges 14a, 15a together and simultaneously compress the rubber elements from a basic circular cross-section into the shape shown. Copper cooling bars 17 having cooling water galleries 18 are then applied to the sides 14b, 15b of the sections 14, 15 as shown and the complete assembly is moved past stationary welding heads 19 which weld the two sections together simultaneously along adjacent edges. The cooling bars 17 act as heat sinks to conduct sufficient heat away from the welding zone to prevent head damge to the rubber elements. Preferably the rubber elements should not be subject to a temperature in excess of 100"C.

Fig. 3 shows an alternative method of cooi- ing the sections during welding and involves the use of a cooling tank having an inlet 50 and an outlet 51 for a constant head of water or other suitable coolant C. The assembly of outer sections 14,15 rubber elements 12 and inner member 11 is positioned in the coolant with the surface S of the coolant C lying against the underside of sides 14b, 15b between the upper and lower surfaces of those sides.

The assembly is moved past the welding head 19 After welding along the portions 14a, 15a, the assembly is inverted to enable the opposite edge portions to be welded together.

It is envisaged that welding may be performed beneath the surface of the coolant in the tank.

In such a case the sections 14, 15 could be welded together along opposite sides simuitaneously as in Fig. 1.

In Fig. 4 the outer member 10 is constructed from four sections 20, 21, 22, 23 each of which defines a corner 16 for locating one rubber element 12. Prior to welding together the four sections, the sections are clamped together by applying forces F. Welding can then be carried out using methods similar to those described with respect to Figs. 2 and 3.

Preferably four welding heads would be used for simultaneous welding of all four sections.

M.l.G. or plasma welding could be used in the methods decribed. As an alternative laser welding could be used. In the latter case, the need for a heat-sink would be less critical and could probably be dispensed with completely.

The welding need not penetrate the full thickness of the material.

Instead of moving the assembly of inner and outer members and rubber elements past the or each welding load, it may be more convenient to move the welding head or welding heads past the assembly to effect fusion.

Whilst the tank of liquid is a convenient form of heat sink, it may be possible to utilise a stream or spray of cooling liquid directed at the fusion zone. In such a case a nozzle may be arranged to move in unison with the assembly or welding head so as to direct the cooling liquid appropriately.

Provided that the heat sink will conduct heat awey sufficiently, it is envisaged that brazing may be used instead of welding.

In Fig. 5 the outer member 10 is constructed from a single sheet of material so as to define corners 16 for the rubber elements (not shown). Free edges of the sheet are formed as out-turned flanges 30. With the rubber elements and inner members in place, forces F are applied to the material as shown to compress the rubber elements as before.

When the flanges 30 reach the Fig. 6 position, a clip 32 (preferably an elongate metal extrusion) is slid longitudinally along the flanges to complete the outer member. If desired the outer member sections in Figs. 2, 3 and 4 could be formed with edge flanges and could be fastened together with clips in a similar manner. It is envisaged that the Fig. 5 outer member could be joined by heat fusion as described above instead of using flanges and a clip.

Further methods of forming a resilient unit will now be described with reference to Figs.

7, 8 and 9 which involve the use of an adhesive. Parts in Figs. 7-9 which correspond to parts in Figs. 1 to 6 carry the same reference numerals.

In Fig. 7, the outer member 10 comprises two U-shaped sections 14,15 each of which defines two corners 16 for locating the four rubber elements 12. To produce the unit, two rubber elements 12 are placed in the lower section 15 and the inner member 11 is then placed in position along with the upper section 14 and remaining rubber elements 12.

Clamping forces F are then applied e.g. by rollers, to the sections 14,15 to urge their adjacent edges 14a, 15a together and simultaneously compress the rubber elements from a basic circular cross-section into the shape shown. Two further U-shaped sections 8,9 are then provided for positioning as shown in Fig. 1 with adjacent edges 8a, 9a thereof displaced by 90 from the edges 14a, 15a. Before being placed in position. The outer surfaces of the sections 14,15 and/or the inner surfaces of the sections 8,9 are coated with an adhesive such as permabond F245 toughened acrylic adhesive used in conjunction with an initiator. However, other suitable adhesives could be used. Once walls 8b, 9b overlap the sections 14,15 sufficiently, the clamping forces F on the latter sections can be relieved.

The inner surfaces of the sections 8,9 are of complementary shape to the outer surfaces of sections 14,15 and the distance X between opposite inner surfaces of each section 8,9 corresponds substantially to the distance between the opposite outer surfaces of the section 14,15 when the rubber elements 12 are compressed as in Fig. 1. The adhesive is then allowed to cure.

In Fig. 8 the outer member 10 is constructed from four sections 20,21,22, 23 each of which defines a corner 16 for locating one rubber element 12.

The sections are clamped together by applying forces F and four metal strips 47 are bonded in the positions shown overlapping the edges of adjacent sections.

In Fig. 9 the outer member 10 is constructed from four sections 50,51,52,53 which overlap each other at positions A. The overlapping portions of the sections are bonded to each other once they have been urged into the position shown to compress therubber elements. Each section 50,51,52,53 defines a corner 56 for locating one rubber element 12.

The bonding required in Figs. 8 and 9 can be effected by the same adhesive mentioned above.

If desired an outer member of the kind shown in Figs. 5 and 6 could have its free edges secured together by adhesive by overlapping the free edges or using a metal strip bonded across them. Alternatively a U-shaped member such as that shown at 8 in Fig. 7 could be applied to the outer member of Fig.

5 so that its walls 8b extend across the sides to which forces F are applied. Where a metal strip or U-shaped member were used, the free edges would terminate as edges 8a, 9a as in Fig. 7 rather than as out-turned flanges 30.

However, the clip 32 of Fig. 6 could be held in place by an adhesive.

Whiist specific reference has been made to four rubber elements, the outer and inner members could be shaped to receive a different number of elements.

Claims

1. A method of producing a resilient unit of the kind described including urging surfaces of the outer member against said resilient elements to compress the elements between the outer and inner members and securing together edge portions of the outer member to maintain the resilient elements in the compressed form.

2. A method according to Claim 2 in which the outer member comprises a plurality of sections.

3. A method according to Claim 2 in which each section defines a corner for locating a said resilient element.

4. A method according to any preceding claim including fusing the portions of the outer member together by welding, brazing or other heat fusion means.

5. A method according to Claim 4 including providing heat-sink means adjacent the area to be fused.

6. A method according to Claim 5 including providing heat-sink means in the form of a cooling liquid.

7. A method according to Claim 6 including providing the cooling liquid as a stream or spray.

8. A method according to Claim 6 including providing the cooling liquid in a tank or other container and immersing the outer member assembled with the inner member and resilient elements at least partially in the liquid.

9. A method according to Claim 8 including immersing the outer member assembled with the inner member and resilient elements fully in the liquid.

10. A method according to Claim 8 including immersing the outer member assembled with the resilient elements so that the level of the liquid lies between inner and outer surfaces of said portions of the outer member.

11. A method according to any preceding claim and where the fusion is effected by heat-fusion means, including effecting relative movement between said heat-fusion means and the outer member assembled with said inner member and resilient elements.

12. A resilient unit formed by a method according to any preceding claim.

13. A method of producing a resilient unit of the kind described including forming the outer member from a plurality of sections each of which defines at least one corner for locating a respective resilient element, urging the outer member sections towards each other so that the resilient elements are compressed between said sections and the inner member, and securing the said sections together.

14. A method according to Claim 13 including using a mechanical securing element to secure together the plurality of sections.

15. A method according to Claim 14 including using a mechanical securing element in the form of a clip.

16. A method according to Claim 15 including providing flanges on the outer member sections and engaging said flanges with the mechanical securing element.

17. A method according to Claim 15 or 16 in which the clip, where provided, is an elongate extrusion which slides along adjacent flanges.

18. A method according to Claim 13 including fusing the portions of the outer member together by welding or other heat fusion means.

19. A method according to Claim 18 including providing heat-sink means adjacent the area to be fused.

20. A method according to Claim 19 including providing heat-sink means in the form of a cooling liquid.

21. A method according to Claim 20 including providing the cooling liquid as a stream or spray.

22. A method according to Claim 20 including providing the cooling liquid in a tank or other container and immersing the outer member assembled with the resilient elements at least partially in the liquid.

23. A method according to Claim 22 including immersing the outer member assembled with the resilient elements fully in the liquid.

24. A method according to Claim 22 including immersing the outer member assembled with the resilient elements so that the level of the liquid lies between inner and outer surfaces of said portions of the outer member.

25. A method according to any of Claims 18 to 24 including effecting relative movement between said heat-fusion means and the outer member assembled with said inner member and resilient elements.

26. A resilient unit formed by a method according to any of Claims 13 to 25.

27. A method of producing a resilient unit of the kind described including forming the outer member from at least one section defining corners for locating respective resilient elements, urging free edges of said section towards each other so as to compress said resilient elements between said section and the inner member and securing the edges together.

28. A method according to Claim 27 including using a mechanical securing element to secure together the free edges of said section.

29. A method according to Claim 28 including using a mechanical securing element in the form of a clip.

30. A method according to Claim 29 including providing flanges on the respective free edges of said section and engaging said flanges with the mechanical securing element.

31. A method according to Claim 30 in which the clip, where provided, is an elongate extension which slides along adjacent flanges.

32. A method according to Claim 27 including fusing the free edges of said section together by welding or other heat fusion means.

33. A method according to Claim 32 including providing heat-sink means adjacent the area to be fused.

34. A method according to Claim 33 including providing heat-sink means in the form of a cooling liquid.

35. A method according to Claim 34 including providing the cooling liquid as a stream or spray.

36. A method according to Claim 34 including providing the cooling liquid in a tank or other container and immersing the outer member assembled with the inner member and resilient elments at least partially in the liquid.

37. A method according to Claim 36 including immersing the outer member assembled with the inner member and resilient elements fully in the liquid.

38. A method according to Claim 36 including immersing the outer member assem bled with the resilient elements so that the level of the liquid lies adjacent said free edges.

39. A method according to any of Claims 32 to 38 including effecting relative movement between said heat-fusion means and the outer member assembled with said elements.

40. A resilient unit formed by a method acccording to any of claims 27 to 39.

41. A method according to any of Claims 1 to 3, 13 to 17 or 27 to 31 including bonding together said edge portions, sections or edges of the outer member to maintain the resilient elements in the compressed form.

42. A method of producing a resilient unit of the kind described including urging surfaces of the outer member against said resilient elements to compress the resilient elements between the outer and inner members, and securing the outer member by adhesive bonding to maintain the resilient elements in the compressed form.

43. A method according to Claim 41 or 42 including forming the outer member from a plurality of sections bonded to each other.

44. A method according to Claim 41, 42 or 43 in which the the sections overlap each other and the overlapping sections are bonded together.

45. A method according to Claim 43 or 44 including holding the sections together by bonding between said sections and one or more members which may extend across edge portions of adjacent sections of said outer member.

46. A method according to Claim 45 in which the or each member is a substantially flat strip or plate of material.

47. A method according to Claim 45 in which the member is a channel-like member.

48. A method according to Claim 47 in which the channel-like member at least partly contains a section or sections forming the outer member.

49. A method according to Claim 48 in which two channel-like members fit around sections of the outer member so that adjacent edges of the respective channels are displaced from adjacent edges of sections forming the outer member.

50. A method according to any of Claims 41 to 49 including using an epoxy resin, anaerobic, cyanoacrylate or other suitable adhesive to effect bonding.

51. A resilient unit formed by a method according to any of Claims 41 to 50.

52. A method of producing a resilient unit substantially as described herein with reference to the accompanying drawings.

53. A resilient unit produced by a method according to Claim 52.