WO2006005942A1

WO2006005942A1 - Bending apparatus

Info

Publication number: WO2006005942A1
Application number: PCT/GB2005/002730
Authority: WO
Inventors: Alan Cunningham
Original assignee: Radius Engineering Limited
Priority date: 2004-07-09
Filing date: 2005-07-11
Publication date: 2006-01-19
Also published as: GB0415501D0

Abstract

A bending apparatus comprises a platen for supporting at least one set point (54) about which an elongate member (62) is to be bent; the at least one set point (54) being connected to a hub (56) by means of a chain (58), wherein the distance between the hub (56) and at least one set point (54) is variable by way of extending or retracting the chain (58).

Description

BENDING APPARATUS

Description:

The present invention relates to forming means.

Forming of plastics can be carried out in a number of ways including, amongst others; extrusion; pulltrusion; injection moulding and bending

operations. Normally, plastics materials are heated to soften or melt them prior to such forming operations, and thereby render them pliable. However, the softening of plastics materials can cause problems such as accidental Deformation or marking during handling or transportation.

The scope of present invention pertains in particular, but not exclusively to bending operations performed on extruded sections of plastics material.

Certain plastics products, for example window frames, can be manufactured from extruded plastics materials. Window frame extrusions usually comprise formations for retaining glazing panels and for securing the frame within an aperture in a building. Such extrusions may have complex profiles in order to accommodate multiple-layer glazing units (i.e. double or

triple glazing panels) and affixing the frame within an aperture of a building may be effected by way of mechanical fastening means (i.e. screws or bolts) or using adhesives or by injecting expanding foam between the frame and

building. For the majority of applications, straight sections of plastics materials are used to form polygonal windows. However, in certain circumstances, it is desirable to have curved window frames for aesthetic

purposes. Examples where curved window frames would be used include circular or arched windows.

In order to manufacture a curved-framed window, it is therefore

necessary to bend straight sections of extruded material into a desired shape.

Normally, such a bending operation is carried out by heating a desired

length of extruded material to its softening point, and by bending it manually

around a template having the desired shape and dimensions of the finished article. For example, unplastsicised polyvinylchloride (PVCu) sections are heated to about 120 degrees centigrade prior to forming.

Whilst this approach is generally satisfactory where large numbers of components are to be manufactured, it is often uneconomical to fabricate a bespoke template for manufacturing small numbers of, or single frames.

Prior art solutions to this problem include the provision of adjustable templates as depicted in Figure 1 of the accompanying drawings, which shows in plan view, a prior art bending apparatus 10 comprising a substantially flat platen 12, having a central boss 14 mounted thereon and a plurality of set points 16 positioned outwardly of the central boss 14 on retractable arms 18.

The platen 12 has a number of grooves 20 therein, corresponding to the locus of each set point 16. There are also provided, locking screws 24 and 22 arranged to grip the inner ends of the arms 18 within the central boss 14 and

the set-points 16 to the platen 12, respectively. A heated elongate member 26 is bent around a former 28, which is

supported at a desired position from the central boss 14 by the set-points.

Figure 2 of the accompanying drawings is a cross section on x-x of

Figure 1 showing how the set points 16 are preventing from moving laterally A by means of a bolt 30 passing through an aperture 32 in the set-point 16,

which is arranged to engage with an undercut 34 part of a groove 20 in the platen 12. The bolt 30 is hand tightened using wing nut 36.

Figure 3 of the drawings shows how, when heated, the elongate member 26 can sag 38 into the grooves 20 of the platen 12, and Figure 4 shows how the sags 38 manifest themselves as unsightly marks on the finished article 40.

Prior art methods for overcoming this problem include the provision of horseshoe-shaped sheets of flat material which is cut to fit around the template and to cover the grooves on the platen. However, a new "horseshoe" is required for each window geometry, leading to additional fabrication time and expense.

The present invention aims to provide an improved adjustable forming means for bending elongate components, which overcomes some of the above problems.

According to the present invention, there is provided a bending apparatus comprising a platen for supporting at least one set-point about which an elongate member is to be bent; the set-point or set-points being connected to a hub by means of a chain, wherein the distance between the hub

and each set point is variable by way of extending or retracting the chain.

In a preferred embodiment of the invention, the chain is a push-chain

and may be manufactured of substantially rigid materials including polymers and metals. Where the chain is a polymeric chain, it is preferably

manufactured of high-density polymers.

A substantially flat platen is a preferred, however, for certain applications, arched or undulating platens may be used. The platen may be manufactured of any suitable material, including plastics, wood, metals or ceramics.

The set points may be formed in such a way as to facilitate the bending operation for example by having rounded or chamfered edges. Preferably, means is provided on each set point to prevent lateral movement of the set point during the bending operation. Suitable means for achieving this objective includes; the provision of suction cups arranged to be affixed to the platen; or magnets that that can be attracted to metallic parts of the platen.

Where provided, set-point fixing means are preferably operable on demand, that is to say, having an engaged state and an unengaged state.

For example; where suction cups are provided, they may be set to

engage or release from the platen manually by way of operating a lever that distorts the diaphragm of the suction cup. Alternatively, pneumatic lines and a vacuum pump connected to diaphragms mounted on the underside of each set

point may be provided whereby the vacuum pump can be switched on to engage the suction cups with the platen, and off to release them. Where

pneumatic means are provided, switching between engaged and unengaged states may be effected by way of a valve on the pneumatic line.

In an alternative embodiment of the invention, the set-point fixing means maybe an electromagnet that is arranged to attract a metallic part of the

platen when an electrical current is supplied thereto. Where desired, metallic parts of the platen may be provided by way of manufacturing the platen from metals or by recessing metallic strips in a non-metallic platen.

In a most preferred embodiment of the invention, two metallic strips are provided in the platen, one at each side of the set-point locus in conjunction with a corresponding pair of outwardly orientated electromagnets. The electromagnets may be arranged to repel the metallic strips by providing a current therethrough in one direction, and to attract the metallic strips by reversing the current. According to this set-up, the electromagnets may be put in repelling mode to guide the set-point along a desired path between the metallic strips whilst it is being extended or retracted; and then put in attracting mode when the set-point is at a desired position, thereby affixing it in-situ.

Switching of the set-point fixing means between engaged and

unengaged states may.be manually, computer or remotely controlled.

A preferred embodiment of the invention shall now be described, by

way of example only, with reference to the accompanying drawings in which;

Figure 1 shows a plan view of a prior art bending apparatus; Figure 2 is a section on X-X of Figure 1 showing how prior art set-points are affixed to the platen;

Figure 3 shows in section, how a heated elongate member can sag into the grooves on the platen;

Figure 4 is a perspective view of the bent elongate member of Figure 3 showing the unsightly effect of the sags of Figure 3 on the finished article;

Figure 5 is a plan view of a preferred embodiment of the present invention showing the elongate member being bent around a former supported on set-points held away from a central boss using push chains and having a reciprocating belt bearing upon the outer face of the elongate member to improve the finish of the elongate member upon cooling;

Figure 6 is a cross section on Y-Y of Figure 3 showing how the set-points can be affixed to the platen using a suction cup;

Figure 7 is a cross section on Y-Y of Figure 3 showing how the set-points can be affixed to the platen using electromagnets acting on metallic strips recessed in the platen;

Figure 8 shows a detail in side elevation of a push chain of a preferred embodiment of the invention being cantilevered between a set-point and a bearing surface within the central hub; and

Figure 9 shows in side elevation, how a plurality of set-points can be extended or retracted using a single actuator acting upon innermost ends of push chains. Referring now to Figure 5 of the drawings, a preferred embodiment of the invention 50 is shown having a platen 52 supporting a plurality of set- points 54 thereon. Each set-point 54 is held at a desired radial position from the central hub 56 by a push chain 58. A flexible former 60 is bent around the set-points 54 for supporting the heated elongate member 62 during the bending operation.

According to a further aspect of the invention, there is provided a bending apparatus comprising; a platen for supporting one or more set-points about which an elongate member is to be bent; and a means for reciprocating the elongate member relative to the set-points.

Preferably, the means for reciprocating the elongate member relative to the set- points is a flexible component arranged to conform to be surface of the elongate member. The flexible component may be a belt or a web.

The flexible component is preferably arranged such that it is retained at one end by a spring means and at the other end by an actuator. Any suitable spring means may be employed, for example a resiliently deformable material such as a rubber, or a coiled spring. The actuator may be a cam, servomotor, ram or any other suitable means being arranged to impart a reciprocating motion to an end of the flexible component.

Thus, Figure 5 of the drawings shows outwardly of the elongate member 62 and the former 60, is a belt 64 for holding the elongate member 62 onto the former 60. The belt 64 is tensioned around pulleys 66 located near to the ends of the elongate member 62. One end of the belt 64 is held by a spring 68 to take up any slack in the belt 64 whilst the other end of the belt is held by a linear actuator 70 for

example, a ram or linear motor. The linear actuator 70 is arranged to

reciprocate, thereby reciprocating the elongate member 62 on the former 60 as

indicated by arrow B. The purpose of the reciprocating belt is to improve the surface finish of the elongate member, and the function that it performs,

replaces the manual equivalent procedure that is well known to those skilled in the art.

Referring now to Figure 6, a section on Y - Y of Figure 5 is shown,

schematically illustrating a set-point 54 of the present invention. The set-point 54 has a recess 72 in the bottom face thereof for receiving a suction cup 74.

There is also provided, a vacuum/air line 76 which can deliver pressurised air or a vacuum from a pump (not shown) to the suction cup 74. Accordingly, the

suction cup 74 can be made to engage with the platen 52 preventing lateral movement of the set-point as shown by arrows C.

Figure 7 shows an alternative section on Y - Y of Figure 5, whereby the

set-points 54 are prevented from moving laterally as indicated by arrows C using electromagnets.

Metallic strips 78 are recessed flush into the platen 52, and the set point 54 has two electromagnets 80 therein orientated towards the metallic

strips 78. Each electromagnet 80 is provided with electrical connections 82 such that they can be made to repel or attract the metallic strips 78 by the selection of suitable currents and polarities. When the set-point 54 is being moved along its locus by its associated

push chain (i.e. out of the plane of the drawing), the electromagnets 80 are set to repel the metallic strips 78. Since the repulsive force on the strips 78 varies according to an inverse square law with distance, the magnetic field generated

by the electromagnets 80 can be used to guide and centre the set-point along a desired locus.

For example: If the set-point 52 were to be displaced laterally as

indicated by arrow D, the force exerted by electromagnet 80' would be greater than that exerted by electromagnet 80. This would have the effect of

encouraging the set-point 54 to move in a direction opposite to arrow D, thereby re-centring it.

Figure 8 shows in side elevation how the push-chain 58 of a preferred embodiment of the invention is supported between a set point 54 a bearing surface 82. The push chain 58 comprises a plurality of parts 59 hingedly connected to one another having formations 84 thereon that prevent the chain 58 from bending under its own weight (as indicated by arrow E) and having cut-away sections 86 that enable the chain 58 to bend as indicated by arrow F. The chain 58 is further restrained by bearing surfaces 88 and 90 that guide it around the bearing surface 82 and keep it straight and inline with a vertical guide 94.

At the innermost end of the chain 58, there is provided a plate 96 that is acted upon by an actuator 98. The actuator 98 is capable of imparting a

substantially linear translation (arrow G) to the plate 96. Thus, by making the actuator move in the general direction indicated by arrow G, the set point 54 can be made to retract H or extend I, relative to the central boss (i.e. 82).

The actuator 98 may be a linear servomotor, hydraulic or pneumatic

ram or any other suitable means for producing linear actuation.

Finally, Figure 9 of the drawings shows an alternative embodiment of the invention whereby a plurality of set points can be made to extend I or

retract H by way of a single actuator 98 acting upon a plurality of plates 96 located at innermost ends of a plurality of push chains 58 connected to the set

points 54. Many features of Figure 9 are analogous to those of Figure 8 and have not been labelled for clarity.

Claims

1. A bending apparatus comprising: a platen for supporting at least one set point about which an elongate member is to be bent; the set point at least one being connected to a hub by means of a chain, wherein the distance between the hub and each set point is variable by way of extending or retracting the chain.

2. A bending apparatus as claimed in claim 1, wherein the chain is a push chain.

3. A bending apparatus as claimed in claim 1 or 2, wherein the chain is manufactured from a rigid material such as polymers and/or metal.

4. A bending apparatus as claimed in claim 3, wherein the rigid material is selected from polymers and metals.

5. A bending apparatus as claimed any one of claims 1 to 4, wherein the chain is made from a high-density polymeric material.

6. A bending apparatus as claimed any one of claims 1 to 5, wherein the platen is substantially flat.

7. A bending apparatus as claimed any one of claims 1 to 5, wherein the platen is substantially arched or undulated.

8. A bending apparatus as claimed any one of claims 1 to 7, wherein the at least one set point has rounded or chamfered edges.

9. A bending apparatus as claimed in any one of claims 1 to 8, further comprising means for preventing lateral movement of the at least one set point.

10. A bending apparatus as claimed in claim 9, wherein the means for preventing are suction cups arranged to be affixed to the platen.

11. A bending apparatus as claimed in claim 9, wherein the means for preventing are magnets arranged to be attracted to metallic parts of the platen.

12. A bending apparatus as claimed in claims 10 or 11, wherein the means for preventing are operable on demand.

13. A bending apparatus as claimed in 12 when appendant to claim 10, wherein the suction cups are set to engage or release from the platen manually by distorting a diaphragm of the at least one suction cup.

14. A bending apparatus as claimed in claim 13, further comprising a pneumatic line and a vacuum pump connected to the diaphragm mounted on the underside of each set point such that the vacuum pump engages and releases the suction cup.

15. A bending apparatus as claimed in claim 13, further comprising a valve for engaging and releasing the at least one suction cup.

16. A bending apparatus as claimed in claim 11 or 12 when appendant to claim 11, wherein the magnets are electromagnets that magnetise when an electrical current is applied thereto.

17. A bending apparatus as claimed in claim 11 or 16, wherein the platen is of metal.

18. A bending apparatus as claimed in claim 11 or 16, wherein the metallic parts of the platen are provided by way of recessing at least one metallic strip in a non-metallic platen.

19. A bending apparatus as claimed in claim 18, wherein the platen has two metallic strips, one at each side of the set-point locus in conjunction with a corresponding pair of outwardly orientated electromagnets.

20. A bending apparatus as claimed in claim 19, wherein the electromagnets are arranged to repel the metallic strips by providing a current therethrough in one direction and to attract the metallic strips by reversing the current.

21. A bending apparatus as claimed in claim 20, wherein the electromagnets are put in repelling mode to guide the set-point along a desired path between the metallic strips whilst it is being extended or retracted and then put in attracting mode when the set point is at desired position, thereby affixing it in-situ.

22. A bending apparatus as claimed in any one of claims 12 to 21, wherein switching the set point fixing means between engaged and disengaged states is manually, computer or remotely controlled.

23. A bending apparatus as claimed in any one of the preceding claim, further comprising a belt for holding the elongate member onto a former.

24. A bending apparatus as claimed in claim 23, wherein the belt is tensioned around pulleys in the proximal area to the ends of the elongate member.

25. A bending apparatus as claimed in claim 24, wherein one end of the belt is held by a spring whilst the other end of the belt is held by a linear actuator.

26. A bending apparatus as claimed in claim 25, wherein the linear actuator is a ram or a motor.

27. A bending apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1/4

FIGURE 2 2/4

FIGURE 4 3/4

4/4

54