US2773537A - Metal-bending machines - Google Patents

Description

Dec. 11, 19576 A. M. REDMAN METAL-BENDING MACHINES 2 Sheets-Sheetl l Filed March 30 1955 ,wrm/Vars United States Patent O 2,773,531 METAL-BENDING MACHINES Albert Maurice Redman, Worcester, England, assignor to Redman Tools & Products Limited, Worcester, England, a British company Application March 30, 1953, Serial No. 345,437 7 Claims. (Cl. 153-46) This invention comprises improvements in or relating to metal-working machines, and relates to methods of and machines for bending and shaping metal bars, strips, rods and like work pieces. In British patent specifica-y tions Nos. 655,560 and 661,041 and the corresponding U. S. Patents No. 2,636,537 and No. 2,680,487, respectively, there are described metal bending machines each comprising the combination of a curved former, means to hold the workpiece in place against the former for shaping, a shoe capable of rolling upon the workpiece against the former, a iluid-pressure-operated ram or its equivalent to press the shoe, workpiece and former together, and means to effect rolling of the shoe against the former, while theram pressure is maintained to shift the place of application of pressure to the workpiece progressively along its surface, the means to hold the workpiece in place serving to clamp against the former one end of the part to he bent and the shoe moving during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end; the present invention relates to machines of this type.

Such machines have made it practicable to produce, by cold bending, curved forms which it was hitherto thought virtually impossible to obtain.

However, with the machines according to British patent specifications Nos. 665,560 and 661,041 and conforming to the above type, there is a limit to `the complexity of the curved forms which can be produced due to the fact that during the bending operation the free unformed part of the workpiece beyond the nip between shoe and former tends to wrinkle and distort or wind out of line with the former as the shoe rolls, if the desired curve is too sharp or the form is too complicated.' Particularly is this so if the workpiece to be formed is a flanged workpiece with flanges along both edges, one of which anges is of much thicker or wider section-than the other; the diierence in width of the flanges tends to result in the workpiece pulling to one side out of line with the former during the bending operation. 'i

According to the present invention, in ametal-bending machine of the type described there is provided, on the side of the nip between shoe and former towards which bending proceeds, a supplementary work-holding member which supports the workpiece against becoming misaligned with respect to the former while being bent. v

In the preferred construction, the 'supplementary work-holding member is carried by the shoe, being mounted to be movable along it, said'member being in slidable engagement with the workpiece during bending and actuating means, such as a fluid-operated piston-andcylinder unit, is provided operatively connected to the supplementary work-holding member to move it along the shoe and workpiece ahead of the place of application of pressure to the workpiece as the latter advances and thereby to keep it clear of the nip between shoe and former.

Preferably, the supplementary work-holding member is mounted to slide along the forming surface ofthe shoe and is spaced from said surface suiciently'to allow a workpiece to pass between the supplementary workholding membervand the shoe while being held closely L Mice against the shoe by the supplementary work-holding member. Thus, in the case where the forming surface of the shoe is concave in the cross-sectional plane at right angles to the plane of movement of the shoe (the former being correspondingly convex) thereby constituting a channel along the shoe, the supplementary work-holding member may be mounted to slide within the channel.

One form of bending machine constructed in accordance with the invention will now be described by way of example and with reference to the accompanying drawings in which:

Figure l is a plan view of the machine, and

Figure 2 is an enlarged perspective view of part of the machine, looking slightly downwards and in the general direction of the arrow 2 of Figure 1, showing one end of the bending shoe of the machine, and also showing the supplementary work holding member in partially withdrawn position.

The machine is primarily for forming motor car bumpers and is, in general, similar to that described in British patent specification No. 665,560, having a heavy main frame l1 upon' which is secured a fixed male former 12 with a convexly curved profile 15 as considered in plan view, and an arm 13 mounted to swing upon the frame 11, in a horizontal plane about a pivot 14 located behind the former profile, which arm 13 spans the former 12 and carries beyond the convex profile 15 a hydraulic piston-and-eylinder unit 16 with its piston rod 31 extending towards the former, the axis of said unit lying in the horizontal plane bisecting the former.

Between the piston-and-cylinder unit 16 and the former there is a shoe 17 for shaping the workpieces, which shoe is in the `forni of a mild steel block about three feet long and with a cross-section about a` foot square; this shoe rests upon a horizontal table 18 over which it is free to slide and which forms part of the swinging arm 13. The piston rod of the piston-and-cylinder unit has a roller nose 19 to bear upon the back of the shoe 17 and press it against the former. The former prole 15 is shaped, in vertical cross-section, to suit the internal form of the motor car bumper it is desired to produce, and the front face of the shoe has a longitudinal recess or channel 20 on a level with the former prole and shaped in crosssection in accordance with the required outside form of the bumper so that it constitutes a movable female former to mate with the fixed male former in shaping the workpiece. n

In addition to the main piston-and-cylinder unit 16 carried on the swinging arm 13 `for applying pressure to the yback of the shoe 17, there is an auxiliary piston-andcylinder unit 2l to Igive a further `degree of control over the movements of the shoe, as described in British patent specification 665,5 60. .The auxiliary unit `has its cylinder pivoted at one end to a carrier 22 mounted to Islide alongside the swinging arm 13 in unison with the piston rod of the main unit r16, and extends `from 4said pivotal connection toward lthe back of the shoe at ,an angle `to the arm 13 and main unit, las viewed in plan. The piston rod of the auxiliary unit is connected lthrough a .pin-andslot connection 23 `whichallows .a certain amount of lost motion `in `a direction substantially parallel rto the axis of the unit to one end of 'a saddle 24 mounted to slide in 'a lhorizontal direction upon 1guides along the back of the shoe 17. The places of action of 'the main :and auxiliary [piston-and-cylinder units upon the back of the shoe are thus `spaced Itherealong so that lthe, units may be employed to controlthe slewing ofthe shoe.

The channel 20 in the `front of the shoe 17 constituting the fem-ale former is provided -with hardened steel liners. A hardened form-block or supplementary work holding member 25 is Vlocated within the channel, and arranged to slide therealong, having at its upper an'dlower faces a pair of male guide members or tenons 26 which run in corresponding guide slots 27 fori-ned in the liners 23 constituting the walls of the channel. The guide slots 27 extend from about midway along the shoe to the end of the shoe which is nearer the place of action of the auxiliary piston-and-cylinder unit 21 than that of 'the main unit 16 and the path -of travel of the lform-block extends for a corresponding distance. To the end of the shoe at which the guide slots terminate are bolted a pair of vertically spaced ybrackets 124, extending horizontally out -frorn the end face of the shoe, and forming trunnion mounting for one end of a hydraulic pistonand-cylinder unit 29 for controlling the movement of the form-block 25. kThe cylinder of the unit extends from the -trunnion mounting toward the shoe and form-block` and has a pistonrod passing into the channel 20 of the shoe and pivotally connected to the form-block.

The form-block 25 is ground on its inner surface facing the channel walls to a lconvex shape in accordance with the cross-section or the male former 12, that is, correspending to the inside shape of the 'finished workpiece, so that there is a gap yat 33 `between said inner surface of the forrmblock and the channel walls, which is equivalent to the `thickness of the metal of a workpiece.

in operation, a straight workpiece, having a shape in t cross section of that -desired in the finished bumper, has one end held to the fixed male former 12 by means of 'a hydraulically-operated clamp 34. Since the workpiece is straight, and the former profile is convex, the Itwo are only in contact for a short distance near the point of clamping. With the main `and auxiliary piston-.and-cylinder units for controlling the shoe retracted, fthe arm 13 carrying the shoe 17 is swung ito a position (Figure l) in which the `main hydraulic unit 16 is in line with the part of the workpiece lying close up to the clamped end thereof (it will be seen that the workpiece is so clamped to the male former 12 that, with the arm 13 in this position, the clamped end is on the opposite side of the axis ot the main hydraulic unit 16 to that on which the auxiliary shoe-control hydraulic unit 21 lies, while the tree unclamped end is on the same side as said auxiliary unit) and the shoe 17 is positioned so vthat its end remote from the hydraulic cylinder 29 controlling Ithe formblock 25 thereon lies between the roller nose 19 of the main hydraulic unit 16 and said part of the workpiece adjacent the clamp 34, .the remainder of the shoe extending away from the clamped end on the far side therefrom of the axis of the main hydraulic unit.

The working cycle is now ready to start, and the machine is switched on. Pressure is applied to the back of the shoe 17 by means of the main hydraulic unit 16 so that the shoe is forced toward the former 12 and driven tightly on to it laround the workpiece over a limited area in line with the taxis of the main hydraulic cylinder. Since the workpiece is straight and its outer shape corresponds to the female profile of the channel 20 in the shoe, it iits snugly over its whole length (except for the clamped end beyond the shoe) into the bottom of the channel in lthe shoe when the shoe is moved on to the male former. At this stage the hydraulic piston-and-cylinder unit 29 controlling the form-block 25 in the shoe channel 20 is in the retracted position, so that `the form-block is drawn right up to the end of the channel, tand since the shoe is a little longer than the unclamped part of the workpiece to be bent, the form-block 25 is clear of the unclamped end of the workpiece, :and does not interfere with the snug fitting thereof into the shoe channel.

Bending of the workpiece is now ready to commence, and at this point a micro-switch is operated, `by the relative `movements of .the machine parts, which actuates a solenoid-controlled vialve admitting hydraulic pressure to the head end :of the form-block operating cylinder 29, and thereby causes the form-block 25 to slide along the shoe channel 20 to the opposite end of its travel. In doing so, the form-block passes in front of the workpiece,

and traps it between the block and the walls of the channel 20. At the same time, the arm 13 carrying the table 13 on which the shoe 17 rests commences to swing slowly in the direction away from the clamped end of the workpiece; in the embodiment illustrated the means for swinging the yarm 13 consists of a horizontal hydraulic piston-and-cylinder traversing unit 32 pivotally connected to the arm as described in British patent specification No. 665,560 but lalternatively the pivot 14 of the arm may be arranged to be bodily movable as described in British patent specification No. 661,041. As the arm 13 swings, the shoe 17 begins to slide on its table 18, and the roller nose 19 of the main hydraulic unit 16 travels along Ithe back of lthe shoe toward the other end thereof, causing the shoe to roll slowly along the workpiece and around the lengthwise curve of the Am'ale former 12, swinging angularly as it does so, but independently of the arm, so thait the 4pressure of the shoe on the workpiece is transferred or 'shifts `gradually and progressively along the workpiece and the metal is progressively `bent around, and shaped on to, the male former. The auxiliary shoccontrol hydraulic unit 21 may ybe employed .to ensure correct slewing of the shoe, in rel-ation to |the curve of the male former, as described in British patent specification No. 665,560.

During the bending operation, after the traversing arm 13 has rotated through a predetermined angular distance the micro-switch associated with the form-block-control piston-andcylinder unit 29 is again actuated automatically, by the relative movement of the parts, to operate the solenoid valve and reverse the iiow of pressure Huid to said piston-and-cylinder unit, which is of the double-acting type, thereby reversing the movement of the forni-block 25 in the shoe channel 2) so that it`commences to withdraw toward the end of the shoe. The iiuid iiowing to and from the head end of the cylinder 29 passes through a non-return check valve which allows free liow into the cylinder chamber, but throttles the How leaving the chamber, so that although the first-described movement 0f the form-block, which takes place at the commencement of swinging of the arm to trap the workpiece, is completed rapidly, the withdrawal of the formblock occurs at a slow controlled rate as the bending proceeds. The check. valve is of the needle-valve type, and the throttle opening may be varied, at will, during the operation of the machine, by means of a valve control handy to the operator, to vary the rate of withdrawal of the form-block.

It will be understood that the form-block 25 acts as a supplementary work-holding member or clamp to control the part of the workpiece which is not clamped to the male former, that is, the part of the workpiece on the side of the nip between shoe and former toward which bending proceeds, and to prevent it from winding or distorting in such manner as to become misaligned with respect to the male former. It is clear that the part of the workpiece which is gripped between the form-block 25 and the walls of the shoe channel 20 cannot become misaligned, despite forces set up by the bending of a workpiece with flanges of unequal width, neither can the part of the workpiece on the side of the form-block remote from the nip between shoe and former at which the actual bending takes place; therefore, for the best operation, the form-block should be kept as close to the nip as it is possible for it to be without actually getting caught in the nip, so as to keep the length of workpiece between the nip and the work-holding form-block as short as possible. The form-block must slide along the workpiece ahead of the nip as the place of application of pressure to the workpiece advances or shifts, and the rate of withdrawal of the form-block. is thus to be controlled in accordance with the speed of rolling of the shoe and the contour of the bent form desired.

Ascan be seen in Figure 1 the space between the shoe 17 and former 12, on the side `of the nip toward which bending proceeds, is acute-angled in plan, and therefore the face 35 of the form-block 25 at the side nearer the nip makes an acute-angle with the surface of the block facing the bottom of the shoe channel 20 in order that the block may be introduced between shoe and former as far as possible toward the nip without fouling the shoe or former; the said acute-angle face 35 is also ground to a form corresponding to the cross-section of the male former profile for the same purpose. ln this manner, the workpiece laterally approaches the nip from a place close by at which it is held in control between the formblock and the shoe, and distortion is thereby obviated; the form-block keeps control of the workpiece during the bending until it clears the end of the workpiece, when only a small portion is left unbent, which is insuicient to distort to any material degree. It will be appreciated that as the bending proceeds to the more sharply curved end of the work, the withdrawal of the form block 25 can be slowed down in relation to the movement of the shoe so that the gap between the nip and the form block decreases. The result is that quite sharply curved forms may be produced with workpieces having iianges of different widths, each workpiece being held in correct alignment with the former throughout the bending, and this has, as far as we are aware, previously been impossible to achieve.

At the end of the bending operation the form-block 25 is fully retracted. The main and auxiliary piston- andcylinder units 16, 21 on the arm 13 are then also retracted, the shoe being pulled 0E the work by means of the auxiliary shoe-controlled unit 21, and the finished workpiece removed. The arm 13 may then be swung back to its starting position ready for the recommencement of the cycle to form another workpiece.

It will be understood that the point at which the microswitch is operated during bending to commence withdrawal of the forrn-block 25 is related to the distance, determined by the guide slots 27, to which the form-block is able to travel along the channel from the end of the shoe, and both these factors are dependent on, and decided according to, the nature of the curved form which it is desired to produce. l

Considerable modification of the machine as described above is possible without departing from the scope of the invention. Thus, it would be possible to arrange a form-block, or equivalent sliding work-holding member, to slide along the face of the shoe for holding a flat unilanged workpiece in correct alignment with the male former, the anging and forming of the desired crosssectional shape of the workpiece, and the lengthwise bending thereof, being carried out in a single operation, instead of in two operations making use of preformed workpieces in the final stage as described above. The main diiiiculty, hitherto, in the flanging and lengthwise bending of workpieces in a single operation in one mathe bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member, situated on the side of the nip between shoe and former towards which bending proceeds, to support the workpiece against becoming mis-aligned with respect to the former while being bent, said supplementary work-holding member being mounted on the shoe to slide along it, and actuating means operatively connected to the supplementary work-holding member to move it while the workpiece is being bent along the shoe and workpiece ahead of the place of application of pressure to the workpiece as said place is shifted, thereby keeping said member clear of the nip between shoe and former.

2. A metal-bending machine comprising a frame, a curved former on said frame, means to hold a workpiece in place against the former for shaping, a shoe capable of v rolling upon the workpiece against the former, pressurechine instead of employing two machines, or carrying out two runs on each workpiece in one machine, has been the control of the loose unclamped metal which, if left hanging with no support, will wind sideways out of alignment with the former as the workpiece is bent; however, the present invention provides a means for holding the unclamped metal in control, and keeping the workpiece in correct alignment during the bending.

I claim:

1. A metal-bending machine comprising a frame, a

curved former'of said frame, means to hold a workpiece in place against the former for shaping, a shoe capable of rolling upon the workpiece against the former, pressure-applying means to press the shoe, workpiece and former together, means to effect rolling of the shoe against the former, while the pressure is maintained, to shift the place of application of pressure to the workpiece progressively along its surface, the means to hold the workpiece in place serving to clamp against the former one end of the part to be bent and the shoe moving during applying means to press the shoe, workpiece and former together, means to effect rolling of the shoe against the former, while the pressure is maintained, to shift the place of application of pressure to the workpiece progressively along its surface, the means to hold the workpiece in place serving to clamp against the former one end of the part to be bent and the shoe moving during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member, situated on the side of the nip between shoe and former towards which bending proceeds, to support the workpiece against becoming misaligned with respect to the former while being bent, which supplementary work-holding member is mounted on the shoe to slide along it in guide-ways provided along the forming surface of the shoe and is spaced from said forming surface sufficiently to allow a workpiece to lie between the supplementary work-holding member and the shoe while being held closely against the shoe by said member, and actuating means operatively connected to the supplementary work-holding member to move it while the workpiece is being bent along the shoe and workpiece ahead of the place of application of pressure to the workpiece as said place is shifted, thereby keeping said member clear of the nip between shoe and former.

y 3. A metal-bending machine comprising a frame, a curved former on said frame having a profile that is convex in cross-section, means to hold a workpiece in place against the former for shaping, a shoe capable of rolling upon the workpiece against the former, which shoe has a forming surface that is concave in the cross-sectional plane at right angles to the plane of movement of the shoe relative to the former so as to t the convex former profile, said forming surface thereby constituting a channel along the shoe, pressure-applying means to press the shoe, workpiece and former together, means to effect rolling of the shoe against the former, while the pressure ismaintained, to shift the place of application of pressure to the workpiece progressively along its surface, the means to hold the workpiece in place serving to clamp against t-he former one end of the part to be bent and the shoe moving during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member situated on the side of the nip between shoe and former towards which bending proceeds to support the workpiece against becoming misaligned with respect to the former while being bent, which supplementary work-holding member is mounted in the channel afforded by the forming surface of the shoe to slide along it and is spaced from said forming surface sufiiciently to allow a workpiece to lie between said surface and the supplementary Work-holding member while being held closely against said surface by said member, and actuating means operatively connected to the supplementary work-holding member to move it while the workpiece is being bent along the shoe and workpiece ahead of the place of application of pressure to the workpiece as said place is shifted, thereby keeping said member clear of the nip between shoe and former.

4. A metal-bending machine comprising a frame, a curved former on said frame, means to hold a workpiece in place against the former for shapnig, a shoe capable of rolling upon the workpiece against the former, pressureapplying means to press the shoe, workpiece and former together, means to effect rolling of the shoe against the former, while the pressure is maintained, to shift the place of application of pressure to the workpiece progressively along its surface, the means tov hold the workpiece in place serving to clamp against the former one end of the part to be bent and the shoe moving during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member, situated on the side of the nip between shoe and former towards which bending proceeds, to support the workpiece against becoming misaligned with respect to the former while being bent, said supplementary work-holding member being mounted on the shoe to slide along it, and a piston-andcylinder unit for actuating the supplementary work-holding member, the cylinder of which is pivotally mounted in brackets on the end of the shoe and the piston rod of which is pivotally connected to the supplementary workholding member, said piston and cylinder unit serving to move said member while the workpiece is being bent along thc shoe and workpiece ahead of the place of application of pressure to the workpiece as said place is shifted, thereby keeping said member clear of the nip between shoe and former.

5. A metal-bending machine comprising a frame, a curved former on said frame, means to hold a workpiece in place lagainst the former for shaping, a shoe capable of rolling upon the workpiece against the former, pressureapplying means to press the shoe, workpiece and former together, means to effect rolling of the shoe against the former, while the pressure is maintained, to shift the place of application of pressure to t-he workpiece progressively along its surface, the means to hold the workpiece in place serving to clamp against the former one end of the part to be bent and the shoe moving during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member mounted to slide along the shoe on the side of the nip between shoe and former towards which bending proceeds to support the workpiece against becoming misaligned with respect to the former while being holding member has projections sliding in guide-slots extending along the -forming surface of the shoe to guide the supplementary work-holding member in its movements, and actuatin 7 means operatively connectedto the supplementary work-holding member to move it while the workpiece is being bent along the shoe and workpiece ahead of the place of application of pressure to the workpiece as said place is shifted, thereby keeping said member clear ofthe nip between shoe and former.

6. A metal-bending machine comprising a frame, a curved former on said frame having a prole that is couvex in cross-section, means to hold a workpiece in place against the former for shaping, a shoe capable of rolling upon the workpiece against the former, which shoe has a forming surface that is concave in the cross-sectional plane at right angles to the plane of movement of the shoe relative to the former so as to fit the convex former prole, said forming surface thereby constituting a channel along the shoe, pressure-applying means to press the shoe, workpiece and former together, means to elect rolling of the shoe against the former, while the pressure is maintained, to shift the place of application of pressure to the workpiece progressively along its surface, the means to hold the workpiece in former one end of the part to be bent and the shoe movbent, which supplementary workplace serving to clamp against the ing during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member situated on the side of the nip between shoe and former towards which bending proceeds to support the workpiece against becoming mis-aligned with respect to the former while being bent, which supplementary workholding member' is mounted in the channel afforded by the forming surface of the shoe to slide along it and has projections sliding in guide-slots extending along said forming surface to guide said member in its movements, said supplementary work-holding member being spaced from said forming surface sufficiently to allow a workpiece to lie between said surface and the supplementary work-holding member while being held closely against said surface by said member, and actuating means operatively connected to the supplementary work-holding member to move it while the workpiece is being bent along the shoe and workpiece ahead of the place of application of pressure tothe workpiece as said place is shifted, thereby keeping said member clear of the nip between shoe and former.

7. A metal-bending machine comprising a frame, a curved former on said frame having a profile that is con- Vex in cross-section, means to hold a workpiece in place against the former for shaping, a shoe capable of rolling upon the workpiece against the former, which shoe has a forming surface that is concave in the cross-sectional plane at right angles to the plane of movement of the shoe relative to the former so as to fit the convex former profile, said forming surface thereby constituting a channel along the shoe, pressure-applying means to press the shoe, workpiece and former together, means to etect rolling of the shoe against the former, while the pressure is maintained, to shift the place of application of pressure to the workpiece progressively along its surface, the means to hold the workpiece in place serving to clamp against the former one end of the part to be bent and the shoe moving during the bending operation in a direction to shift the place of application of pressure to the workpiece away from the clamped end, a supplementary work-holding member situated on the side of the nip between shoe and former towards which bending proceeds to support the workpiece against becoming mis-aligned with respect to the former while being bent, which supplementary work-holding member is mounted in the channel afforded by the forming surface of the shoe to slide along it and has projections sliding in guide-slots extending along said forming surface to guide said member in its movements, said supplementary work-holding member being spaced from said forming surface sufiiciently to allow a workpiece to lie between said surface and the supplementary work-holding member while being held closely against said surface by said member, and a piston-and-cylinder unit for actuating the supplementary work-holding member, the cylinder of which is pivotally mounted in brackets on the end of the shoe and the piston rod of which is pivotally connected to the supplementary work-holding member, said piston and cylinder unit serving to move said member while the workpiece is being bent along the shoe and workpiece ahead of the place of application of pressure to the workpiece as said place is shifted thereby keeping said member clear of the nip between shoe and former.

References Cited in the tile of this patent UNITED STATES PATENTS 1,379,858 Gail May 31, 1921 1,462,315 Akey July 17, 1923 1,982,164 Hoener Nov. 27, 1934 2,142,443 Goin Ian. 3, 1939 2,255,867 Wisckol Sept. 16, 1941 2,636,537 Redman Apr. 28, 1953 2,680,467 Redman June 8, 1954

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