WO1997029871A1

WO1997029871A1 - Wire straightening apparatus

Info

Publication number: WO1997029871A1
Application number: PCT/GB1997/000413
Authority: WO
Inventors: Antonio Andrew Perna
Original assignee: Pave Automation Design And Development Ltd.
Priority date: 1996-02-15
Filing date: 1997-02-14
Publication date: 1997-08-21
Also published as: EP0880415A1; WO1997029872A1; DE69703343T2; ATE197005T1; AU1802197A; DE69703343D1; EP0880415B1; AU1802097A

Abstract

Apparatus for straightening an elongate material, such as a wire (2; 512) from a coiled stock (6) comprises a pair of counter rotating rotary members (12, 14; 508, 510) through which the wire is fed. The wire (2; 512) is fed through a succession of engagement members such as sleeves (114; 588, 600) which radially deflect the wire (2; 512). Consequently the wire follows a path which is co-axial with the rotary member (12, 14; 508, 510) as it enters and leaves the latter, but is deflected along its substantially helical path as it travels therethrough. Each engagement member is rotatably mounted on the rotary member so that the torsional forces exerted on the engagement members on the wire (2; 512) and the wear on the engagement members by the passage of wire therethrough are reduced. There is also provided a wire bending machine which incorporates such straightening apparatus.

Description

TITLE; WIRE STRAIGHTENING APPARATUS

Field of the Invention

This invention relates to apparatus for straightening wire or other elongate material, and to a machine which is operable to bend such material and which incorporates such apparatus.

Background to the invention

Some types of wire straightening machine are able to accept a wire from a coiled stock. In such a machine, the wire is fed from the stock to a bending head of the machine via a wire straightener which straightens the wire so that it can then be bent into the desired shape by the bending head.

An example of a wire straightener comprises a pair of axially spaced cylindrical spinners which, in use, rotate in opposite senses around their respective axes. The wire is fed from one end to the other of the spinners, each of which deflects the wire causing it to travel along a helical path.

Although the wire which passes from the spinners is straight, it can include some residual twist which results in the shape of the final piece of bent wire deviating from the desired shape.

In addition, the surfaces of the spinners which engage the wire are prone to wear, and as a result the spinners have to be adjusted frequently to take into account the effects of this wear. A skilled technician is needed to perform the adjustments, and the wire bending machine is not operative while adjustment is taking place. Summary of the Invention

According to a first aspect of the invention, there is provided apparatus for straightening elongate material, the apparatus comprising at least one rotary member, guide means mounted on the rotary member and operable to guide the wire through the rotary member, as the latter rotates, along a path the end regions of which are substantially coaxial with the axis of rotation of the rotary member, the guide means having deflection means which comprise an engagement member for engaging the wire to deflect it away from said axis of rotation as it travels along said path, wherein the engagement member is rotatable relative to the rotary member about the axis of rotation of the latter, or an axis substantially parallel to the portion of the path at the engagement member.

The rotatable engagement member will tend not to rotate relative to the wire as the latter is fed through the rotary member, and therefore exerts less torsional force on the wire than an engagement member which is rotationally fixed relative to the rotary member. In addition any frictional wear of the engagement member by the wire is reduced so that the apparatus can be operated for a relatively long time before the engagement member has to be readjusted or replaced.

Preferably, the deflection means further comprises an annular support which surrounds said path, and the engagement member is mounted for rotation about the inner periphery of the support.

Preferably, the engagement member comprises a sleeve which surrounds said path and which is preferably mounted on the inner periphery of the annular support through low friction rolling elements, preferably ball bearings.

Preferably, the annular support and engagement member is one of a pair of such supports and engagement members, radially and axially spaced from each other so that the engagement members deflect the wire in opposite radial directions relative to the axis of rotation of the rotary member.

Preferably, the guide means includes axial annular supports positioned upstream and downstream of the deflection means, and arranged to guide the wire along the axis of rotation of the rotary members.

Preferably, each axial support has a respective further engagement member for engaging the wire to guide the latter along said axis, wherein each said further engagement member is mounted on the inner periphery of its respective annular support for rotation relative to the support about the axis of rotation of the rotary member.

This further reduces the torsional forces exerted on the wire by the rotary member, and the frictional wear of the guide means.

Preferably, the rotary member is one of two such members which are operable to counter rotate, and which are so positioned that the wire passes through first one and then the other rotary member, in use.

The apparatus preferably includes drive means for rotating said rotary members, feed means for feeding the wire through the rotary members and control means for controlling the operation of the drive means so that, while the wire is being fed through the rotary members, there is maintained a substantially constant ratio of the speed of rotation of at least one of the members to the speed with which the wire passes through the rotary members.

According to a second aspect of the invention, there is provided a machine for bending elongate material, such as wire, the machine comprising straightening apparatus according to the first aspect of the invention, a bending head situated downstream of the straightening apparatus for bending the elongate material into a desired shape and feed means for feeding the material through the straightening apparatus and thus to the bending head.

Preferably, the straightening apparatus is mounted on a carriage which is moveable in either direction parallel to the direction in which the material is fed through the machine.

There are instances where it is preferable to draw elongate material back in to the machine a short distance in the direction opposite the normal feed direction, whereas it is desirable for the wire to travel through the rotary members in only one direction. The carriage enables this to be done without feeding wire through the or each rotary member in the reverse direction.

Brief Description of the Drawings

Three embodiments of wire straightening apparatus, in accordance with the invention, will now be described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic isometric view of a wire bending machine fitted with one embodiment of wire straightening apparatus;

Figure 2 is a sectional side view of a rotary member of the wire straightening apparatus;

Figure 3 is a cross-sectional view taken along the line III-III of Figure 2;

Figure 4 is a sectional side view of one of a number of deflection members forming part of the rotary member; Figure 5 is a more detailed sectional side view of one of the components shown in Figure 4;

Figure 6 is a partially exploded perspective view of a region of the rotary member between its two ends;

Figure 7 is an exploded sectional view of an end region of the rotary member;

Figure 8 is a sectional side view of part of the rotary member, showing wire passing therethrough;

Figure 9 is a sectional side view, corresponding to Figure 2, of the rotary member of the second embodiment of wire straightening apparatus;

Figure 10 is a longitudinal sectional view of a housing forming part of that rotary member;

Figure 11 is an end view of the housing;

Figure 12 is a front view of one of the components housed in the housing;

Figure 13 is a sectional side view of that component;

Figure 14 is a sectional view along the line XIV-XIV in Figure 12;

Figure 15 is an end view of one of two end fittings for the housing (of either embodiment);

Figure 16 is a sectional side view of that end fitting; and

Figure 17 is a plan view of another component of the rotary member of the second embodiment. Figure 18 is a plan diagram of part of a bending machine in accordance with the invention, the machine incorporating the third embodiment of straightening apparatus;

Figure 19 is a partially sectioned side view of part of the third embodiment including a rotary member;

Figure 20 is a simplified partially sectional view of the rotary member with a wire extending therethrough the member being so arranged that the wire extends along its axis;

Figure 21 is a similar more detailed, partially sectioned, more detailed view of the rotary member when arranged radially to deflect a wire;

Detailed Description

Figure 1 shows a bending machine having a bending head 1 to which a wire 2 is fed by a feed mechanism 4 from a coiled stock 6. The machine includes a rotatable gripper mechanism 8 for rotating the wire 2 about its own axis, and wire straightening apparatus 10 which is interposed between the feed mechanism 4 and the stock 6.

The straightening apparatus 10 comprises a pair of co-axial cylindrical rotary members, referred to as spinners, 12 and 14 which are arranged in series and connected to a motor 16 through a pulley and belt transmission 18 and a gear box 20.

The motor 16 is operable to rotate the spinners 12 and 14 respectively in a clockwise and an anticlockwise direction as viewed in Figure 1 at an angular speed which is controlled by a control unit 22.

The spinners 12 and 14 are identical, and only the components of the spinner 12 will be described in detail. Referring to Figure 2, the spinner 12 comprises a hollow cylindrical housing 34 which contains seven axially-spaced cylindrical bodies 35-41.

The axis of each cylindrical body is substantially perpendicular to the elongate axis of the housing 34, and the ends of each housing extend into a respective pair of diametrically opposed circular apertures in the housing 34. Those apertures are indicated by the reference numerals 44-57 (apertures 48 and 44) being more clearly shown in Figures 6 and 7 respectively), and are of a slightly larger diameter than that of the cylindrical bodies 35-41 so that the bodies 35-41 can be inserted into and removed from the housing 34 through the apertures, and the ends of the bodies are accessible through the apertures when the bodies are in position in the housing 34.

The bodies 37-39 are identical with each other, and only the body 37 will therefore be described in detail.

With reference to Figures 3-6, the body 37 is formed with two flat end faces 60 and 62, each of which is surrounded by a respective one of two cylindrical peripheral walls 64 and 66 which are formed as extensions to the sides of the body 37. The walls 64 and 66 have part circular portions formed at their outboard ends, and each of the walls includes a pair of opposed slots. The slots in the wall 64 are denoted by the reference numerals 68 and 70, whilst reference numerals 72 and 74 denote the slots in the wall 66.

As can be seen from the drawings, particularly Figure 4, the face 60 is closer to the inboard ends of the slots 68 and 70 than is the face 62 to the inboard ends of the slots 72 and 74.

With the body 37 in place in the housing 34, the slots 68 and 70 atingly engage a bar 76 which extends, in the direction of the axis of the housing 34, across the aperture 48, and which is screwed at either end to the housing 34. The slots 72 and 74 matingly engage a similar bar 78 which extends across the aperture 49. The engagement of the slots with the bars 76 and 78 provides angular location of the body 37 in the housing 34, and also prevents the body 37 from dropping out of the housing 34 through either of the apertures 48 and 49.

The bars are partially accommodated in two opposed recesses 79 and 81 (Figure 7) running along the length of the housing 34.

The bars 76 and 78 include central screw-threaded bores through which two screw-threaded adjustment shafts, respectively referenced 80 and 82, extend. The ends of the shafts 80 and 82 external to the housing 34 are terminated in heads 84 and 86 for facilitating the rotating of the shafts so as to vary the distance by which they extend radially into the housing 34.

The opposite ends of each shaft engages a respective one of the faces 60 and 62, so that the shafts provide radial location for the body 37 relative to the housing 34. The external portions of the shafts also carry locking nuts 88 and 90 which define (adjustable) limits of movement of the shafts into the body 34.

With reference to Figure 4, the body 37 has a central passage 92 which includes a reduced diameter exit 94, and which is stepped so as to define two annular shoulders 96 and 98. The shoulders 96 and 98 are situated between the exit 94 and an annular groove 100 which accommodates a removable circlip 110.

The circlip 110 helps to hold a deep-groove ball bearing 112 against the shoulder 98. The deep-grove ball bearing 112 provides rotatable mounting for a cylindrical sleeve 114 which extends through the bearing 112, and which includes a radial outer flange 116 at one end, and an annular groove 118 in the region of irs other end.

The flange 116 is of a larger diameter than the inner periphery of the bearing 112, whilst the annular groove 118 accommodates a circlip 120 which is also of a larger diameter than the inner periphery of the bearing 112. Thus, the sleeve 114 is retained in position in the bearing 112 by the engagement of the flange 116 and circlip 120 with the bearing 112.

The sleeve 114 is shown to an enlarged scale in Figure 5, from which it can be seen that the inner surface of the sleeve has two curved end portions 122 and 124 disposed one on either side of a central, untapered cylindrical portion 126.

The components shown in Figure 4 can all be inserted into or removed from the housing 34 as a single sub-assembly. The bodies 38 and 39 contain identical bearings, sleeves and circlips, those components forming identical sub-assemblies to that shown in Figure 4, and are retained in position by identical arrangements of bars, screws and adjustments shafts, to those used for the body 37.

Each of the bodies 36, 40 and 41 is identical to the body 35 and contains identical components to those contained in that body.

The body 35 is shown in more detail in Figure 7, and forms part of another sub-assembly which is identical to the sub-assembly shown in Figure 4 in all features other than the shape of the body. In this case, the body 35 is, in the section shown in Figure 2, symmetrical about the axis of the housing 34. Thus, the body has two end faces 130 and 132 which are spaced by the same distance from the inboard ends (for example 134 and 138) of the slots in the corresponding peripheral walls 140 and 142 which surround the faces 130 and 134. Since the components housed within the body 35 are identical to those in the body 37, they have been denoted in Figure 7 by identical reference numbers followed by the symbol ' .

The spinner 12 also includes identical end pieces 146 and 148. The end piece 146 is shown in more detail in Figure 15 and 16, and takes the form of a cylinder which includes a radial outer end flange 150 and two diametrically opposed slots 152 and 154 which provide rotational key to a complementary cylindrical inlet guide 156 of the spinner 12 (Figures 1 and 2).

The corresponding slots in the end piece 148 provide a rotational key to a complementary cylindrical connector 158 which connects the member 12 to the output of the gearbox 20.

Bodies 35 and 36 are held in position by two bars 160 and 162 which engage in the slots in the ends of the bodies 35 and 36. The bar 160 extends across the apertures 44 and 46, whilst the bar 162 extends across the apertures 45 and 47. Both bars are screwed to the body 34 by the fixing screws 163-168 as shown in Figure 2. A similar arrangement of bars and fixing screws retains the bodies 40 and 41 in position. When so retained, the bodies 35, 36, 40 and 41 are so positioned that their central passages, and hence the sleeves therein, are co-axial with the axis of the body 34.

The body 38 is inverted relative to the bodies 37 and 39 so that the end face of the body 38 which is closer to the inboard end of its corresponding slot is downwardly facing when the bodies are orientated as shown in Figure 2. With the rotary member set up as shown in Figure 2, the screw-threaded adjustment shafts have been so positioned that the sleeves within the bodies 37-39 are co-axial with the axis of the housing 34. When in this position, the body 38 is at the top of its range of allowable motion (when orientated as shown in Figure 2) whilst the bodies 37 and 39 are at the bottom of theirs.

When the bodies are so positioned, the wire 2 may be readily "threaded" through the rotary member (the tapered entrances to the sleeves facilitate the threading process). Once the wire 2 has been threaded through the rotary member, the adjustment shafts for the members 37-40 are altered until the members are in positions such as are shown in Figure 8, in which the sleeves in the members 37 and 40 are radially displaced in one direction relative to the axis of the housing 34, whilst the sleeve in the body 38 is radially displaced in the opposite direction.

On its passage through the spinner 12, the wire 2 is deflected by the sleeve in the rotary member 37 along a path which has an initial curved portion 170 followed by a second portion 172 which is substantially parallel with the axis (denoted by 174) of the housing 34 before the wire reaches a third curved portion 176. Each of the sleeves in the bodies 38 and 39 deflects the wire along a path which has a respective set of three similar portions. The co-axial sleeves in the pairs of bodies 35, 36 and 40, 41 cause the path of the wire 2 to be co¬ axial (with the spinner axis) respectively before and after the radial displacement by the sleeves shown in Figure 8 occurs.

Since the spinner 12 rotates as the wire is fed therethrough, the radial displacement caused by the sleeves shown in Figure 8 results in the wire travelling along a generally helical path.

Figure 9 shows a spinner of the second embodiment of wire straightening apparatus. That spinner is identical to the spinner 12 (and hence the spinner 14) in all respects apart from the arrangement of sleeves at the entrance and exit of the spinner (and apertures in the body for accommodating the associated cylindrical bodies) and the means of retaining the cylindrical bodies within the housing. Accordingly, features corresponding to those of the spinner 12 are indicated by the same reference numerals raised by 200.

Instead of having four axial end sleeves contained in corresponding bodies (35, 36, 40 and 41) the spinner of the second embodiment has two axial end sleeves 400 and 402 of extended length. Those sleeves are mounted by deep-groove ball bearings 404 and 406 in cylindrical bodies 408 and 410 of enlarged diameter compared with the bodies 237-239. Apart from their dimensions, the bodies 408 and 410 and bearings 404 and 406 are identical to the other bodies and bearings of the spinner. The shape of the body 408 (and hence the body 410) is indicated in greater detail in Figures 12-14. The body 234 has correspondingly enlarged apertures 409 and 411 for accommodating the ends of the bodies 408 and 410.

Each of the other bodies of the second embodiment, unlike those of the first embodiment, is not held in place by a respective pair of bars. Instead, all three bodies 237, 238 and 239 are retained and angularly located in the housing 234 by a single pair of opposed common bars 412 and 414. Each bar is held in position by a respective set of four screws which extend into screw-threaded holes (some of which are visible in Figure 10) in the body 234. the bar 412 is shown in more detail in Figure 17, from which it will be seen that the bar includes four large diameter apertures for accepting the screws for fixing to the body 234 and three smaller dimension apertures, arranged in alternative relationship with the large diameter apertures which accommodate the screw-threaded radial adjustment shafts for the bodies 237-239.

Referring back to Figure 1, the control unit 22 is connected to, and controls the speed of operation of a motor 24 on the feed mechanism 4. The motor 24 is, in turn, connected to a screw-threaded shaft 26 though a belt and pulley transmission 28.

The shaft 26 extends through a screw-threaded passage in a block 30. The screw-threads on the shaft 26 and in the passage complement each other so that rotation of the shaft 26 moves the block 30 therealong. The block 30, in turn, carries a pneumatic clamp 32 through which the wire 2 extends. The control unit 22 also controls the operation of a fixed pneumatic clamp 420 which forms part of the feed means 4 and is situated downstream of the reciprocating clamp 32.

The clamp 420 holds the wire 2 during the return strokes of the reciprocating clamp 32, but is released from the wire 2 when the latter is being held by the clamp 32 during its advance strokes (which feed the wire 2 through the apparatus).

The control unit 22 so controls the speed of operation of the motors 16 and 24 that each of the spinners 12 and 14 undergoes one complete revolution for each inch of wire 2 drawn therethrough. Thus, if the wire 2 is drawn through the spinners 12 and 14 at a speed of 1 metre per second during advance strokes of the clamp 32, the rotary members 12 and 14 are rotated at a speed of 2,362 rpm. However, at the end of the advance stroke of the clamp 32, and during its subsequent return stroke, there is no feed of the wire 2 through the spinners 12 and 14. During this time, therefore, there is correspondingly no rotation of the spinners 12 and 14.

The clamps 32 and 420 can be operated to feed the wire through the machine in a reverse direction, which enables certain shapes of wire to be formed by the head 1. However, it is undesirable to feed the wire through the spinners 12 and 14 in a reverse direction, and to avoid this the wire straightening apparatus 10 is mounted on a carriage (not shown) for moving the apparatus in a reverse direction during such reverse feed of the wire.

The wire twisting apparatus 8 comprises a motor 422 connected to a releasable clamp 424 via an intermediate gear wheel 426. When the wire 2 is not being fed through the machine (in either direction) the clamp 424 is operable to grip the wire 2 and the motor 422 to rotate the clamp 424 to twist the wire 2 about its own axis to enable the bending head 1 to form wire products which are bent in more than one plane. The bending head 1 is similar to the bending head used on the CNC-9 O ni-Forming Centre produced by Pave Automation Design and Development Limited, and comprises a pair of opposed guide projections 428 and 430 through which the wire 2 passes, and a finger 432 mounted on a rotatable support 434. The support 434 is, in turn, connected to a motor 436 through gear wheels 438 and 440, and is, in use, rotated by the motor 436, thus causing the finger 432 to bend the wire 2 against either of the projections 430 and 428. The bending head 1 is connected to pneumatic cylinder 442 which is operable to move the bending head in a direction perpendicular to the wire axis. This enables the finger 432 to be moved clear of the wire 2 so that subsequent rotation of the support 434 can move the finger 432 to either side of the wire 2. ire products which have been bent at the bending head 1 are subsequently severed from the rest of the wire by a guillotine 444 situated downstream of the head 1.

With reference to Figure 18, the third embodiment of wire straightening apparatus is also operable to apparatus 501 shown in Figure 18 straightening apparatus 501 which straighten wire from a coiled stock before the wire is fed to a bending head similar to the head 1 for bending portions of the wire into a desired shape. Such a portion is then separated from the rest of the wire by means of a guillotine similar to guillotine 444, positioned upstream of the bending head.

The third embodiment of wire straightening apparatus comprises a pair of axially aligned cylindrical spinners 508 and 510 arranged in series. The wire, referenced 512, passes through the spinner 508 and then through the spinner 510. The spinners are mounted for rotation about an axis defined by the wire 512, and the spinner 508 is connected to a motor 514 through a toothed belt 516 which extends around a pulley wheel attached to the output of the motor 514 and a further pulley wheel which is attached to the end of the spinner 508, and which is hollow to allow the wire to pass therethrough. A similar arrangement of a toothed belt 518, and pulley wheels, connects the spinner 510 to a motor 520. The motors 514 and 520 are operable to rotate the spinners 508 and 510 in opposite senses about the axis defined by the wire 512.

In Figures 18 to 20, the arrows F indicate the normal direction of feed of the wire 512 through the machine.

The structure of the spinner 508, which is identical to the spinner 510, is shown in more detail in Figures 19 to 21.

Referring to Figure 19, in which the wire has been omitted for the sake of clarity, the components of the machine are mounted on a frame, part of which is shown at 524, which carries a rail (not shown) on which a carriage 522 is slidably mounted. The carriage 522 supports the spinners 508 and 510 and motors 514 and 520, and is able to slide along the rail in either the same or the opposite direction as the feed direction for the wire 512. The position of the carriage 522 relative to the frame is monitored by means of a linear potentiometer 526 which is attached at one end to the carriage 522 and at the opposite end to the portion 524 of the frame. An air spring 528 also extends between the carriage 522 and frame of the machine, and biases the carriage 522, and hence all components carried thereby in a direction opposite the feed direction of the wire 512.

In certain circumstances, the wire 512 has to be retracted through the machine by a short distance (in the opposite direction to the normal feed direction). This happens if, for example, the guillotine is to cut the wire at a distance from the nearest bend which is less than the distance separating the bending head and the guillotine. Thus, if the bending head and guillotine are separated by 120mm, the wire must be retracted by 70mm if it is to be cut at 50mm from the last bend formed by the head 1. If the wire is partially retracted, the air spring moves the carriage 522 in the same direction to prevent the wire travelling through the spinners in a reverse direction. The output of the potentiometer 526 is monitored by a computer (not shown) which ensures that no further retraction of the wire occurs if the carriage 552 is at the end of its path of movement in the direction opposite to the arrows F.

Subsequent forward feed of the wire (with the spinners stationary) moves the carriage 552 back away from that position. The carriage 552 may optionally be fitted with a clamp (not shown) which cooperates with a rail (not shown) on the frame of the machine to fix the position of the carriage during forward feed of the wire 512.

A housing 530 is attached to the carriage 522, and a tubular shaft 544 is rotatably mounted on the housing 530 through a pair of axially spaced deep-groove ball bearings 534 and 538. The pulley wheel which engages the drive belt 516 is referenced 504 and is attached to the shaft 544.

The downstream end of the shaft 544 is attached to an annular end stop 546 for the spinner 508, the body of which is formed from eight contiguous hollow annular sections, 548, 550, 552, 554, 556, 558, 560 and 562. The end stop 546 is attached to a lug 564 via a screw 566, and the lug 564 engages a corresponding recess in the section 548 rotationally to key the section 548 to the stop 546.

The opposite side of the section 548 includes an annular axial ridge, 570 which extends parallel to the axis defined by the wire 512, and which engages in a corresponding annular recess in the section 550. Each of the sections 550, 552, 554, 556, 558 and 560 includes a similar respective ridge which engages in a corresponding recess in the next section (in the direction of feed of the wire 512). Each section of the spinner 508 includes four through bores which register with the bores in the other sections to define a pair of offset diametrically opposed passages through the spinner. The spinner is held together in angularly fixed relative positions by means of four nut and bolt connectors, only one of which is shown (at 606 in Figure 21). Each of the connectors extends through a respective one of the passages.

The section 562 at the downstream end of the spinner 508 is attached to a tubular shaft 572. The shaft 572 is mounted on a housing 578 through deep groove ball bearings 574 and 576. The housing 578 is, in turn, mounted on the carriage 522.

The downstream face of the section 550 includes a central cylindrical recess 580 which is provided with a deep groove ball bearing comprising an annular lining 582. The inner periphery of the lining 582 includes an annular groove which acts as a race for a number of ball bearings, two of which are shown at 584 and 586, through which a central sleeve 588 is mounted for rotation relative to the section 550 about the axis defined by the wire 512. The sections 552, 558 and 560 have identical arrangements of deep groove ball bearings.

The sections 554 and 556 are identical, and only the features of section 556 shall therefore be described. The section 556 also has a recess 587 in its downstream face, but this is rectangular and accommodates a rectangular housing 589 of a length less than that of the recess 587. The position of the housing 589 in the recess 587 is adjustable by means of grub screws 590 and 592 which extend into the recess 587 through respective, diametrically opposed, screw-threaded passages in the section 556.

The housing 589 includes a central circular aperture which contains a grooved lining 594 similar to the lining 582. The groove in that lining acts as a race for ball bearings, two of which are shown at 596 and 598 through which a sleeve 600 is rotatably mounted in the housing 589. The corresponding recess and housing and sleeve in the section 554 are respectively referenced 602, 603 and 605.

As can be seen more clearly from Figure 21, the recess 587 is offset lengthwise from the centre of the downstream face of the section 556. The recess 602 in the section 554 is similarly offset.

With the spinner set up as shown in Figure 20, the grub screws associated with the sections 554 and 556 are so set up that the housings 603 and 589 are positioned so that the sleeves 600 and 605 are aligned with the sleeves in the sections 550, 552, 558 and 560, and hence with the centres of the tubes 544 and 572. In use, the sleeves 600 and 605 are radially offset as shown in Figure 21. Thus the wire 512 is guided through the spinner 508 along a path which is initially coaxial with the axis of rotation of the spinner, but which is then deflected away from that axis by the sleeve 605. The wire 512 is then radially deflected in the opposite direction to the opposite side of the axis of rotation by the sleeve 600 before being returned to the axis of rotation by the sleeves in the sections 558 and 560. Since the radial offset of the wire 512 occurs while the spinner 508 is rotating, the sleeves attached to the sections 554 and 556 cause the wire 512 to follow a helical path through the spinner 508.

Since the wire 512 only engages the spinner at the rotatable sleeves, no surface of the spinner 508 rotates on the wire 512 as the latter passes through the spinner, since those sleeves rotate relative to the spinner, and therefore can remain angularly stationary relative to the wire. This reduces the torsional stresses applied to the wire 512 by the spinner 508 and also helps to reduce the wear on the sleeves, and hence the need to readjust the spinner 508 by adjustment of the grub screws in the sections 554 and 556, or by replacement of any of the sleeves.

Claims

1. Apparatus for straightening elongate material, the apparatus comprising at least one rotary member, guide means mounted on the rotary member and operable to guide the elongate material through the rotary member, as the latter rotates, along a path the end regions of which are substantially co¬ axial with the axis of rotation of the rotary member, the guide means having deflection means which comprise an engagement member for engaging the elongate material to deflect it away from said axis of rotation as it travels along said path, wherein the engagement member is rotatable relative to the rotary member about the axis of rotation of the latter, or about an axis substantially parallel with the axis of rotation of the rotary member.

2. Apparatus according to claim 1, in which the deflection means further comprises a support having an annular support surface which surrounds said path, and the engagement member is rotatably mounted on the support.

3. Apparatus according to claim 1 or claim 2, in which the engagement member comprises a sleeve which, in use, surrounds said path.

4. Apparatus according to claim 3 when appended to claim 2, in which the engagement member is mounted on the inner periphery of the support through low friction rolling elements.

5. Apparatus according to claim 4, in which the rolling elements comprise ball bearings.

6. Apparatus according to any of claims 2 to 5 in which the support and engagement member are one of a pair of such supports and engagement members, radially and axially spaced from each other so that the engagement members deflect the wire in opposite radial directions relative to the axis of rotation of the rotary member.

7. Apparatus according to any of the preceding claims, in which the guide means includes axial annular supports positioned upstream and downstream of the deflection means, and arranged to guide the wire along the axis of rotation of the rotary member.

8. Apparatus according to claim 3 in which each axial support has a respective further engagement member for engaging the wire to guide the latter along said axis, wherein each said further engagement member is mounted on the inner periphery of its respective annular support for rotation relative to the support about the axis of rotation of the rotary member.

9. Apparatus according to any of the preceding claims, in which the rotary member is one of two such members which are operable to counter rotate, and which are positioned in series, so that the wire passes through first one and then the other rotary member, in use.

10. Apparatus according to claim 9, in which the apparatus includes drive means for rotating said rotary members, feed means for feeding the wire through the rotary members, and control means for controlling the operation of the drive means so that, while the wire is being fed through the rotary members, there is maintained a substantially constant ratio of the speed of rotation of at least one of the members to the speed with which the wire passes through the rotary members.

11. A machine for bending elongate material, such as wire, the machine comprising straightening apparatus according to any of claims 1 to 10, a bending head situated downstream of the straightening apparatus for bending the elongate material into a desired shape and feed means for feeding the material through the straightening apparatus and thus to the bending head.

12. Apparatus according to claim 11, in which the straightening apparatus is mounted on a carriage which is moveable in either direction parallel to the direction in which the material is fed through the machine.