WO1997029872A1

WO1997029872A1 - Straightening apparatus

Info

Publication number: WO1997029872A1
Application number: PCT/GB1997/000414
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: DE69703343D1; EP0880415A1; AU1802197A; WO1997029871A1; DE69703343T2; AU1802097A; ATE197005T1; EP0880415B1

Abstract

Apparatus for straightening elongate material such as wire (2) comprises a rotary member (12, 14) through which the material is fed, and which includes deflection means (for example sleeve 114) for deflecting the material regularly as it passes through the rotary member. The rotary member (12, 14) is driven at a controlled speed by a motor (16) controlled by a control unit (22) which also controls a feed mechanism (4) for feeding material through the rotary member (12, 14) at a controlled rate. The control unit (22) is operable to cause a rotation speed of the rotary member to increase and decrease in response to corresponding variations in the rate at which the material is fed through the rotary member. For example, the rotary member may rotate at a speed directly proportional to the rate of feed of the elongate material.

Description

STRAIGHTENING APPARATUS

Field of the Invention

This invention relates to apparatus for straightening elongate material, such as wire, and to a wire bending machine fitted with such apparatus.

Background to the Invention

Several types of known wire bending machines include a wire bending head which is supplied, by feed means, with wire from a coiled or rolled stock. In order to enable the bending head to bend the wire into a desired shape, the wire is first fed through wire straightening apparatus interposed between the bending head and the stock.

One example of wire straightening apparatus is discussed in UK Patent No. 2185921 (Benton) and comprises a pair of counter- rotating spinners, each having a respective set of rollers between which the wire is fed. The rollers deflect the wire, as it travels through the spinners, and this deflection straightens the wire.

However, it is normally necessary to feed the wire through a bending machine at a variable rate, and at times to hold the wire stationary (relative to the bending head) while a piece of the wire is being bent into shape. It has been found that, as a result, the spinners can burn through or cause work hardening of the wire. The Benton reference acknowledges the former problem, but does not discuss the latter, and fails to give any clear explanation of the possible causes or solution to those problems. Summary of the Invention

According to a first aspect of the invention, there is provided apparatus for straightening wire, the apparatus comprising a rotary member through which the wire passes, deflection means for deflecting the wire as it passes through the member, drive means for rotating the rotary member, control means connected to the drive means and operable to control the speed of rotation of the rotary member, the control means also being connectable to feed means for feeding wire through the rotary member at a variable rate, wherein the control means is operable to cause the rotational speed of the rotary member to increase and decrease in response to corresponding variations in the rates at which wire is fed through the rotary members.

Preferably, the control means is so arranged that there is substantially no rotation of the rotary member while the wire is stationary.

It has been found that, by varying the speed of rotation of the rotary member in accordance with the feed rate of wire, damage, such as "burn through" or work hardening, of the wire by the rotary member can be reduced or avoided.

Preferably, the control of the feed means and drive means is such that the speed of rotation of the rotary member is proportional to the rate at which wire is fed through the passage, the ratio between rotational speed and feed rate thus being substantially constant.

Preferably, the control means is operable to cause the drive means to rotate the rotary member by between one half and six (preferably five) revolutions for every inch (2.54 cm) of wire fed therethrough.

Thus if, for example, the wire is being fed through the rotary member at a rate of 1 metre per second, the control means will cause the rotary member to rotate at around 2,360 rpm if the member is to rotate once for every inch of wire fed therethrough, around 11,800 rpm in order to achieve five revolutions per inch of wire, or around 14,160 rpm if a rate of six revolutions per inch is required.

The feed means may form part of the apparatus, or may constitute part of a wire bending machine in which the apparatus is installed.

Preferably, the rotary member is one of a pair of such members, and the drive means is operable to cause the rotary members to counter-rotate.

Preferably, each rotary member includes guide means 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, and the deflection means 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.

The invention also lies in a method of straightening wire by the steps of feeding wire through a rotating rotary member so as to deflect the wire radially relative to the axis of rotation of the rotary member, wherein the speed of rotation of the rotary member is substantially proportional to the rate at which wire is fed therethrough.

The invention also lies in a wire bending machine having wire straightening apparatus in accordance with the first aspect of the invention.

Brief Description of the Drawings Two 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 wire straightening apparatus in accordance with the invention;

Figure 2 is a sectional side view of a rotary member of one embodiment 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 of 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.

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 matingly 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-groove 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 its 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 140 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 adjustment shafts, to those used for the body 37.

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 end (for example 134 and 138) of the slots in the 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 indicated 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.

(Figure 1). 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.

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

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 an alternative 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 hars. 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 alternating 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 through 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-8 Omni-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. Wire 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.

Claims

1. Apparatus for straightening elongate material, the apparatus comprising a rotary member through which the material passes, deflection means for deflecting the material as it passes through the member, drive means for rotating the rotary member, control means connected to the drive means and operable to control the speed of rotation of the rotary member, the control means also being connectable to feed means for feeding material through the rotary member at a variable rate, wherein the control means is operable to cause the rotational speed of the rotary member to increase and decrease in response to corresponding variations in the rates at which material is fed through the rotary member.

2. Apparatus according to claim 1, in which the control means is so arranged that there is substantially no rotation of the rotary member while the material is stationary.

3. Apparatus according to either of the preceding claims, in which the control means is operable to cause the speed of rotation of the rotary member to be directly proportional to the rate at which material is fed through the passage, the ratio between rational speed and feed rate thus being substantially constant.

4. Apparatus according to claim 3, in which the control means is set up to cause the drive means to rotate the rotary member through between one half and six revolutions for every inch of material fed therethrough.

5. Apparatus according to claim 4, in which the control means is set up to cause the drive means to rotate the rotary member through five revolutions for every inch of material fed therethrough. 6. Apparatus according to any of the preceding claims, in which the rotary member is one of a pair of such members, and the drive means is operable to cause the rotary members to counter-rotate.

7. Apparatus according to claim 6, in which each rotary member includes guide means operable to guide the 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, and an engagement member for engaging the 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 an axis substantially parallel to the axis of rotation of the rotary member.

8. A method of straightening wire by the steps of feeding wire through a rotating rotary member so as to deflect the wire radially away from the then back to the axis of rotation of the rotary member, wherein the speed of rotation of the rotary member is substantially proportional to the rate at which wire is fed therethrough.

9. A wire bending machine having wire straightening apparatus in accordance with any of claims 1 to 7.