GB2275219A

GB2275219A - Bending apparatus

Info

Publication number: GB2275219A
Application number: GB9303441A
Authority: GB
Inventors: Graham J Benstead
Original assignee: BTR PLC
Current assignee: BTR PLC
Priority date: 1993-02-20
Filing date: 1993-02-20
Publication date: 1994-08-24
Anticipated expiration: 2013-02-20
Also published as: GB9303441D0; GB2275219B

Abstract

Elongate material is bent by use of bending apparatus comprising a support frame (41), a former (10) rotatably mounted in the frame and selectively locatable relative to the frame in any one of a plurality of prescribed angular positions, the former (10) providing a surface (13, 14) about which elongate material may be deformed, retention means (47) to hold the former (10) in said selected position relative to the support frame (41), deformation means (52) for applying bending pressure to the elongate material to cause it to be bent around the former and stop means (25, 26) associated with the former to restrict angular movement of the deformation means (52). <IMAGE>

Description

BENDING OF ELONGATE MATERIAL This invention relates to an apparatus for and a method of bending elongate material such as strips, including tubes, of metal and other permanently deformable materials. It relates in particular, though not exclusively, to the bending of metal tubes and rods.

A requirement to bend metal tubes arises often when installing electrical conduits and gas or water supply pipes. An example of a portable bending machine for use in such installations work is that described in the specification of GB Patent 1175331. That machine comprises a bending arm pivoted about the centre of curvature of a part-circular former having a grooved periphery against which a length of pipe is bent to conform with the radius of the former. The bending arm carries a roller rotatable about an axis parallel to the pivot axis of the arm. The machine is provided with an elongate guide which is grooved along one side to rest on the length of pipe to be bent and is flat along the opposite side to provide a contacting surface for the roller as the bending arm is swung to bend the pipe by pressure applied through the intermediary of the guide.

Whilst a machine of the aforedescribed type works effectively to bend tubes and rods, it is not well adapted for bending material accurately to a particular pre-selected angle.

It is possible to provide a portable bending apparatus adapted for bending material to a pre-selected angle from a range of angles by use of a special former such as that described in the specification of GB Patent 2051632B. That former employs a variable position stop in the form of a pin which is inserted through a peripheral region of the former, across a part-circumferentially extending groove in the periphery of the former. As strip material is bent by movement of a bending arm, that movement is arrested when the strip material is prevented from further deformation into the former groove upon abutment with the variable position stop pin.

Whilst this apparatus operates reliably and satisfactorily, care is necessary, particularly when bending tubes of thin wall section and/or soft material to ensure that the tube is not overstressed and distorted when it comes into contact with the stop pin.

The present invention seeks to provide a bending apparatus for and a method of bending elongate material to a selected angle from any of a wide range of angles.

In accordance with one of its aspects the present invention provides a bending apparatus comprising a support frame, a former rotatably mounted in the frame and selectively locatable relative to the frame in any one of a plurality of prescribed angular positions, the former providing a surface about which elongate material may be deformed, retention means to hold the former in said selected position relative to the support frame, deformation means for applying bending pressure to the elongate material to cause it to be bent around the former and stop means associated with the former to restrict angular movement of the deformation means.

Typically the bending apparatus additionally comprises material support means for retaining elongate material in position against a part of the former prior to and during operation of the apparatus to bend material about the former.

The former may be provided with a plurality of circumferentially spaced openings or other location formations each alignable with at least one opening or other formation in the support frame whereby retention means such as a retention pin insertable through a hole in the support frame and a selected one of the holes in the former may be employed to retain the former in a pre-selected angular position relative to the frame.

The former preferably comprises a protruberance or other formation adapted to act as said stop means to be abutted by the deformation means at least when said means is moved in a first direction of rotation.

Rotation of the deformation means may be inhibited in a direction opposite to said first direction for example by the structure of the support frame or the former may incorporate stop means which restricts rotation of the deformation means in each of the two directions of angular movement.

Said deformation means may be in the form of a bending lever mounted to be otherwise free to rotate about the axis of the former.

The bending lever may incorporate a roller whose axis of rotation is parallel to the axis of rotation of the bending lever and whose spacing from said axis of rotation may be pre-set or may be selectively adjustable having regard to size variations of strip material to be deformed.

Where the bending lever incorporates a roller, said roller may be arranged to act directly on the strip material in the manner in which in the aforementioned GB 2051632 the variable position bar 13 directly contacts the strip material 10.

Alternatively the roller may act via a guide, such as one shaped to the profile of the elongate material to seek to avoid distortion of the profile of the strip material; an example of use of such a guide is that described in the aforementioned GB 1175331.

The support means for retaining elongate material in position for bending normally will be fixed in position relative to the support frame.

The former may be of a multi-purpose type comprising for example two side-by-side groove formations of different lengths. The two groove formations may have similar or different cross-sectional profiles. Thus, in the case of a former adapted for the bending of circular section tubes, one part of the former may have a first length and a groove of a first radius of curvature for bending tubes of a first diameter to a first radius of curvature, and the other part of the former may have a different length and cross-sectional radius of curvature thereby to enable tubes of a different outer diameter to be bent to a different radius of curvature.

The or each former typically will have a groove which extends at least part in a circumferential manner to facilitate bending to a uniform radius of curvature.

The support frame may have a pointer or like marker means associated therewith for use as a datum reference for positioning of elongate material prior to bending.

Marks may be pre-applied to the elongate material at positions in accordance with pre-tabulated information and thereby assist, in combination with the marker means, in achieving a desired degree of set, e g a required spacing of successive bend zones.

In accordance with another of its aspects the present invention provides a method of bending elongate material comprising providing bending apparatus comprising a support frame, a former rotatably mounted in the frame and selectively locatable relative to the frame in any one of a plurality of prescribed angular positions, selecting the former to lie in one of said prescribed angular positions and positioning retention means to hold the former in said angular position relative to the support frame, said apparatus additionally comprising a bending means rotatably mounted for rotation about the axis of rotation of the former and able to engage stop means associated with the former, positioning elongate material against a first circumferential region of the former at a position remote from a distal end of the elongate material, operating material support means to secure the elongate material in position relative to said portion of the former and then operating the bending means to act on the elongate material to deform it against the former, and continuing movement of the bending means until said means comes into abutment with said former stop means.

The method of the invention additionally may comprise selecting the angular position by reference to pre-tabulated data which give the required angular position of the former for attaining a desired bend angle in elongate material of specified cross-sectional dimensions.

One embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a plan view of a former of a bending machine in accordance with the present invention; Figure 2 is a side view of the former of Figure 1; Figure 3 is a plan view of apparatus in accordance with the present invention, and Figure 4 is a side view of the apparatus of Figure 3.

The former 10 for use in the bending machine 11 of the present invention will be described first.

The former 10 comprises a central disc portion 12 to respective sides of which lie a pair of integrally formed part-circular former portions 13,14, one 13 having a larger radius of curvature than the other 14.

Each former portion 13,14 has an edge groove l3',l4' which is semi-circular in cross-section (see Figure 1) and extends circumferentially through an angle of approximately 2300. Each groove lies between a pair of flange formations 15,16; 17,18, one flange formation 16 for the larger groove being defined by said central disc portion 12.

The former portions 13,14 each have substantially flat edge surfaces 19,20 to interconnect between ends 21,22 of the respective grooves.

Adjacent the flat surfaces 21,22 the former portions each have at an axially outwards position an integrally formed abutment 23,24. Each abutment 23,24 presents at its ends a pair of abutment stops 25,26 arranged to restrict movement of a bending lever as described below. The abutment stops 25,26 of a pair are aligned as viewed in Figure 2 to lie in a common plane spaced from the central axis 27 of rotation of the former by approximately half the width W (see Figure 4) of the bending lever. Each pair of stops 25,26 has therebetween an arcuate zone to provide a recess 28 which allows free rotation of a pivotally mounted end of the bending lever.

The former is provided with nine location holes 30, of a through-hole type, to enable it to be secured to a support frame in any one of nine positions. The location holes are spaced equally from the axis 27 of the former and lie circumferentially spaced at positions relative to the abutment stops 25,26 which, in use of the apparatus, are appropriate for bending of a tube or other elongate material of appropriate size to any pre-selected one of four angles of deformation. Four positions are used to give different, selected, angles when the bending lever is rotated in one direction ( e g pulled down from above), four other positions provide similar angles of deformation when the lever is rotated in an opposite direction (i e pulled up from below) and the ninth is a neutral position, where no angular restraint acts upon the bending lever during rotation.

The bending machine comprises also a collapsible frame having four legs 40 (see Figures 3 and 4) pivotally mounted in conventional manner to a machine body 41. The former 10 is rotatably mounted on the body for rotation about its major axis 27.

The machine body 41 is of a U-shape form to provide a pair of arm portions 42,43 to which the former is mounted. The body has an auxiliary flange 44 provided with a first opening 45 which lies spaced from the axis 27 of the former by a distance corresponding to the radial spacing of the location holes 30 from that axis so a retention pin 47 may be fitted through the flange opening 45 into any one of the nine location holes of the former.

The auxiliary flange 44 has a second opening 46 spaced from the opening 45 and also alignable with the former location holes. This allows the former to be located in a greater number of positions relative to the frame than if the flange 44 had only the single opening 45. Provision of the two openings 45,46 suitably spaced apart has the further advantage that the former may be located relative to the frame at either of two angular positions which are close together and in particular which are closer than the minimum practical spacing of two successive former location holes.

The auxiliary flange 44 is positioned close to one side of the central disc portion 12, namely to that side at which the smaller former portion 14 is situated. The arm portion 42 nearest the other former portion 15 is provided with two holes aligned with the flange openings 45,46 to receive the retention pin 47. Thus the pin is supported in a balanced manner by the body 41 at each of its ends.

The spacing of the body arms 42,43 is sufficient to accommodate not only the axial thickness of the former 10, but also the thickness of a pair of arms 50,51 which form the bending lever 52. The bending lever is pivotally mounted about the axis 27 of the former and incorporates a pair of rollers 53,54 having edge formations profiled in known manner so as to co-operate with the edge formations of the former 10 to cause material to be bent against the former upon movement of the bending lever.

The machine body 41 incorporates a conventional stop support 55 for the elongate material so as to hold stationary an end of that portion of material which is subject to deformation during use of the machine. The stop support 55 comprises two support zones 56 only a lower one of which is illustrated (in Figure 4). The other support zone is located at a position symmetrically located above the horizontal line extending through the axis 27. The stop zones 56 allow material to be supported above or below the former for deformation either by downwards or upwards movement respectively of the bending lever 52.

In use of the bending machine material is arranged to be supported and/or clamped by one of the support zones 56 of the support stop 55 at a position adjacent one end of the portion of material to be bent. The former 10 is rotated relative to. the machine body 41 to a desired position which is then retained by inserting the retention pin 47 through an opening in the arm 42 and a flange opening 44,45 to locate with one of the former location holes 30 selected having regard to the desired angle of bend. The bending lever 52 is then rotated from a rest position to bend the material, the movement being continued until the bending lever abuts one 25 of the abutment stops carried by the former.

The use of a former which is rotatable allows any one of a number of set angles to be pulled in a pipe or tube, in either direction, before the bending lever comes to rest against a stop on the former.

When the bending lever is rotated, the roller may act directly on the side of the pipe or tube, as specifically described in the above example, or the force may be applied through a guide, which is shaped to the diameter of the pipe on the inside face, to restrict distortion to the profile of the pipe.

Claims

1. Bending apparatus for elongate material comprising a support frame, a

former rotatably mounted in the frane and selectively locatable relative to the frame in any one of a plurality of prescribed angular positions, the former providing a surface about which elongate material may be deformed, retention means to hold the former in said selected position relative to the support froze, deformation means for applying bending pressure to the elongate inaterial to cause it to be bent around the former and stcp means associated with the former to restrict angular serent of the deformation means.

2. Bending apparatus in accordance with claim 1 and comprising support means for retaining elongate material against a part of the former prior to and during operation of the apparatus to bend material about the former.

3. Bending apparatus in accordance with claim 2 wherein A said support means is fixed in position relative to the support frame.

4. Bending apparatus in accordance with any one of the preceding clams wherein the former is provided with a plurality of circumferentially spaced location means each alignable with at least one formation in the support frame whereby said retention means may co-operate with said at least one formation in the support frame and a selected one of the location means in the former to retain the former in a pre-selected angular position relative to the frame.

5. Bending apparatus in accordance with any one of the preceding claim wherein said stop means in a formation provided on the former and adapter to abutted by the deformation means when said means is roved in at least a first direction of rotation.

6. Bending apparatus in accordance with claim 5 wherein structure of the support frame inhibits rotation of the deformation means in a direction opposite to said first direction.

7. Bending apparatus in accordance with claim 5 wherein the former comprises stcp means which restricts rotation of the former in each of two directions of angular mocesent.

8. Bending apparatus in accordance with any one of the preceding claims wherein the deformation mans comprises a bending lever mounted to rotate about the axis of the former.

9. Bending apparatus in accordance with claim 8 wherein the bending lever incarporates a roller the axis of rotation of which s parallel to the axis of rotation of the bending lever.

10. Bending apparatus in accordance with claim 9 wherein the spacing between the axis of rotation of the roller and the axis of rotation of the bending lever is selectively adjustable.

11. Bending apparatus in accordance with claim 9 wherein said roller is arranged to act directly on the elongate material.

12. Bending apparatus in accordance with claim 9 or claim 10 wherein the roller acts on the elongate material via a guide shaped to the profile of the elongate material.

13. Bending apparatus in accordance with any one of the preceding claims wherein the former comprises two side-by-side groove formations of different lengths.

14. Bending apparatus in accordance with any one of the prec ding claims wherein the former comprises at least one grove which extends at least in part in a circrofenntial manner.

15. Bending apparatus in accordance with any one of the preceding clans wherein the support frame comprises marker means adapted for use as a datum reference for positioning of elongate material prior to bending.

16. Bending apparatus in accordance with claim 1 and substantially as described herein with reference to the drawing8.

17. A method of bending elongate material comprising providing bending apparatus comprising a support frame, a former rotatably mounted in the frame and selectively locatable relative to the frame in any one of a plurality of prescribed angular positions, selecting the former to lie in one of said prescribed angular positions and positioning positioning reteon means to hold the former in said angular position relative to the support frame, said apparatus additionally canarising deformation means rotatably mounted for rotation about the axis of rotation of the former and able to engage stop means associated with the former, positioning elongate material against a first circumferential region of the former at a position remote fran a distal end of the elongate material, arranging material support mans to secure the elongate material in position relative to said portion of the former and then operating the deformation means to act an the elongate material to deform it against the former, and continuing nrwerrrent of the deformation means until said means ccmes into abutment with said former stop means.

18. Method in accordance with claim 17 and comprising selecting said angular position by reference to pre-tablulated data which give the required angular position of the former for attaining a desired bend angle in elongate material of specified cross-sectional dimsmrions.

19. Method in accordance with claim 17 or claim 18 wherein a nPrk is preapplied to the elongate material at a position in accordance with pre tabulated information to assist in achieving a desired degree of set.

20. method in accordance with claim 17 and substantially as described herein with reference to the drawings.