Patent Publication Number: US-10328476-B2

Title: Bending machine

Description:
FIELD OF THE INVENTION 
     The invention relates to a bending machine for bending metal workpieces. 
     PRIOR ART DISCUSSION 
     U.S. Pat. No. 4,870,849 describes a clamp die assembly for tube bending. GB566226 describes a machine with two dies operating in tandem. GB468406 describes a machine having formers mounted on a turret. U.S. Pat. No. 1,473,101 describes an iron bender with bars having holes to receive pins. CN202984375 describes a pipe bending machine with a moving seat and a fixed die. 
     Also, it is known to provide a bending machine which has a die on a vertical post and a counter die on a lever arm. The lever arm is rotated to move the counter die with respect to the die, with sufficient force to bend the workpiece. 
     The invention is directed towards providing a bending machine which is simpler and/or more versatile, and/or more accurate. 
     SUMMARY OF THE INVENTION 
     According to the invention, there is provided a bending machine comprising:
         a die support shaft,   at least two working arms:
           mounted to rotate about the die support shaft, and   arranged to each support a counter die and to rotate about the die support shaft to move the counter dies to bend a work-piece in conjunction with a die on the die support shaft, and   
           a drive for the working arms, said drive comprising a translational drive driving link arms pivotally connected to the working arms.       

     In one embodiment, the translational drive comprises a ram. 
     In one embodiment, the translational drive acts on a pivot joint or joints interconnecting the link arms. 
     In one embodiment, the translational drive acts on a longitudinal axis extending through a longitudinal axis of the die support shaft. 
     In one embodiment, the die support shaft has a through-hole for the translational drive, and the die support shaft may be of integral construction. 
     In one embodiment, the working arms have a plurality of counter die support fixtures. In one embodiment, said fixtures include holes or sockets. 
     In one embodiment, the machine further comprises a counter die support arranged for mounting on a working arm and supporting a die. This provides for indirectly supporting a counter die on a working arm, giving the possibility of further adjustment of the counter die position with respect to the working arm. In one embodiment, said support is adapted to allow adjustment of position of a counter die with respect to the working arm. In one embodiment, the adjustment is infinite. In one embodiment, the supports are arranged to support counter dies asymmetrically. In one embodiment, the adjustment is translational. 
     In one embodiment, the machine comprises a die drive mechanism arranged to directly rotate a bearing for a die or a die. This provides for roller bending, with traversal of the work-piece through the machine. In one embodiment, the die drive mechanism is dedicated to a die bearing or die. In one embodiment, the die drive mechanism has a gear transmission. 
     In one embodiment, the die drive mechanism has a manual or automatic actuator. 
     In one embodiment, the die drive mechanism comprises a feature for engaging a working arm at a location spaced apart from the bearing, to prevent rotation of the die drive mechanism. In one embodiment, said feature is spaced apart by a distance corresponding to separation of two engagement features of a working arm. The feature may be a pin for engaging a hole in the working arm. 
     In one embodiment, the machine comprises a plurality of die drive mechanisms, and said mechanisms are arranged to operate in synchronism for roller bending of a work-piece. In one embodiment, said die drive mechanisms are inter-linked. In one embodiment, said die drive mechanisms have inter-engaging gears. 
     In one embodiment, the die support shaft is rotatable on a fixed machine base for adjustment of orientation of the machine. 
     In one embodiment, the machine comprises a lock for locking a working arm, causing at least one joint to be static and other joints to be movable in a plane normal to the die support shaft axis. 
     In one embodiment, the machine further comprises means for locking the translational drive to prevent it from rotating with respect to a machine base. In one embodiment, a pivot joint of a working arm is hollow and is arranged to support a die, and a rotational drive extends through said joints to apply rotational drive to a die. 
     In one embodiment, the joint is between a link arm and a working arm. 
     In one embodiment, the base includes a hydraulic drive arranged to pump oil through conduits in the die support shaft to the working arm drive. 
     In one embodiment, the machine further comprises a die support comprising a plate with a slot to guide translational movement of a die. 
    
    
     
       DETAILED DESCRIPTION OF THE INVENTION 
       Brief Description of the Drawings 
       The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:— 
         FIGS. 1 and 2  are plan views of a bending machine of the invention, showing different positions of die-support working arms; 
         FIG. 3  is a side view of the machine; 
         FIGS. 4( a ), ( b ), and ( c )  are front, side, and plan views respectively of a main spindle; 
         FIGS. 5 and 6  are plan and side views of the machine ready to start bending a tube, and 
         FIG. 7  is a plan view after it has bent; 
         FIGS. 8 and 9  are side views showing mounting of a roller die assembly, and  FIG. 10  shows the machine ready for use with this roller die assembly; 
         FIG. 11  shows addition of a motorized die actuator; 
         FIGS. 12 and 13  are plan views showing use of a pair of adjustable counter die supports; 
         FIG. 14  shows use of a hook for guiding a work-piece; 
         FIG. 15  shows a tooting arrangement for a V-bend; 
         FIG. 16  shows an alternative bending machine of the invention; 
         FIGS. 17 and 18  show the machine of  FIG. 16  in use set up for section rolling of a tube; 
         FIGS. 19 and 20  show the machine of  FIG. 16  in plan and elevation set up for sharp bending up to 90°; 
         FIG. 21  shows a die assembly with a built-in drive; 
         FIG. 22  shows a bending machine incorporating three dies with built-in drives, in this case incorporating gears; and 
         FIG. 23  shows a machine incorporating three dies with interconnected gears. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIGS. 1 to 4  a bending machine  1  is for three-point bending in a versatile manner. The machine  1  comprises a main spindle  2  which extends vertically. The spindle  2  is non-rotating during a bending operation. However, it may be rotated about a base  40  for desired orientation of the machine main working parts. 
     Two working arms  3  are pivotally mounted on the main spindle  2  under action of link arms  4 . The link arms  4  are connected to each other at their outer ends by a pivot joint  5  and are each connected at their inner ends to a working arm  3  by a pivot joint  21  on a lug  20 . The working arms  3  each have a series of holes  22  for receiving counter dies. 
     Each working arm  3  also has posts  23  which interconnect two arm plates  3 ( a ) and  3 ( b ), joining the plates so that they form a unit. This spreads the bearing load in the vertical direction on the main spindle  2 . 
     The link arms  4  each comprise two arm plates  4 ( a ) and  4 ( b ) joined by pillars  4 ( c ) and spacers  4 ( d ). 
     To ensure accuracy, the spindle  2  is mounted on the base  40  by connection by a bronze bearing in a protractor ring  30 . The ring  30  is in turn fixed to the remainder of the base  40 . 
     All of the machine  1  above the disc or ring  30  is rotatable by rotation of the spindle  2  in the bearing in the ring  30 . A particular angular position for the upper part of the machine with respect to the base may be locked by one or more of three clamps  31 . One clamp  31  locks the ram  6  to prevent it rotating, but leaves everything else free to rotate, as shown in  FIGS. 1 and 2 . The other two clamps  31  lock a working arm  3  to the ring  30 . These are only used for particular modes of operation where it is desired to prevent one of the working arms from rotating, as described in more detail below. 
     A working arm drive is in this embodiment a ram  6  having a cylinder  7  which passes through the spindle  2  and a piston  8 . This provides a translational, linear, drive along a horizontal longitudinal axis which passes orthogonally through the vertical axis of the main spindle  2 . 
     There is a piston follower  35 , a piston follower clamp  36 , and a valve/switch  37 . The purpose of the piston follower  35  is to support the clamp  36  so that it can be locked to any desired position along its length. The clamp  36  in turn acts as a stop which contacts a push-to-open valve  37  which is mounted to the piston follower guide which in turn is mounted to the hydraulic cylinder  7 . As the piston  8  extends the follower  35  follows it, moving the clamp  36  to the left as viewed in  FIG. 3 . The clamp  36  will contact the valve  37  spool and activates the valve, oil is diverted back to the hydraulic tank, in turn stopping the linear motion of the ram, thus enabling bends to be reproduced accurately. 
       FIG. 3  shows a pin  50  for insertion in one of the holes  22  of a working arm  3  to support a counter die, as described in more detail below. 
     As shown most clearly in  FIG. 4 , the main spindle  2  is machined from a single piece of steel. It has a vertical shaft  2 ( a ), and an integral fixture  2 ( b ) through which there is a hole  2 ( c ) for the cylinder  7  and a hole  2 ( d ) for the piston follower. This arrangement allows the main spindle  2  perform the roles of:
         a common pivot joint for the working arms  3  (which support the counter dies),   a support for the die,   a guide and an attachment point for the drive ram  6  for moving the link arms  4 .       

     There is a hexagonal head  2 ( e ) on top of the spindle  2  for preventing rotation of a die mounted on the spindle  2 . 
     The spindle  2  has the holes  2 ( c ) and  2 ( d ) perpendicular to its axis, through one of which the hydraulic cylinder passes and is attached by means of a nut, and the other one through which the piston follower  35  passes. It is also the vertical axis about which the machine above the base  40 / 30  rotates, independently of its base  40  and the degree plate (protractor ring)  30 . The spindle  2  also has a threaded hole through its axis, through which a bolt and washer assembly can secure tooling. As the hydraulic cylinder  7  passes through the hole  2 ( c ) in the main spindle  2 , the hex orientation for die support cannot change relative to the cylinder. 
     There are three ring clamps  31 , one of which is attached to the cylinder of the hydraulic ram, the other two being attached to each working arms  3 . Only one clamp  31  can be activated at any one time. 
     Referring to  FIGS. 5 and 6  there are two pin counter dies  50  pegged into holes  22  of the working arms  3  and a die  51  on the main shaft  2 . There is a hexagonal index plate  53  over the die  51 , to prevent the die from rotating about the main spindle (using six bolts  52 ). 
     In one example of operation a straight tube work-piece W 1  is placed horizontally between the counter dies  50  on one side and the die  51  on the other. Operation of the hydraulic ram  6  to extend the piston  8  pulls, via the link arms  4 , the working arms  3  so that the tube W 1  is formed around the die  51 , as shown in  FIG. 7 . 
     This is merely one example of a very wide variety of ways in which the machine  1  can be used to form workpieces. Any of many different types of dies and counter dies may be mounted, the positions of the counter dies may be selected by choice of hole  22  to use or it may be infinitely adjustable by using a counter die support on at least one of the working arms  3 . 
     Extension of the piston  8  causes symmetrical movement of the arms  3  and  4  about the longitudinal axis of the ram  6 . Example positions are shown in  FIG. 1  (piston  8  retracted),  FIG. 2  (piston  8  fully extended),  FIG. 13  (only partially extended). 
     The machine may be used even if one of the working arms  3  is locked by for example a clamp  31  to the base  30 / 40 . In this case, there are two fixed pivot joints, the main shaft  2  and one of the joints  21 . The other joint  21  and the link arm joint  5  move in the horizontal plane, and the piston  8  drives the joint  5 . The ram  6  and the opposing working arm  3  rotate about the axis of the main spindle  2 , albeit at different speeds i.e. the ram  6  moves at half of the degrees of rotation of the opposing working ram. 
     The machine could also be used, for example, if the ram  6  is locked by a clamp  31  to the degree ring  30 . In this case there is a fixed pivot joint  2 . Both of the joints  21  and  5  move in the horizontal plane. Both of the working arms  3  rotate about the axis of the main spindle  2  with equal degrees of rotation. 
     Referring to  FIGS. 8 and 9  two ball bearing counter dies  55  are mounted on the working arms, and a roller die assembly  56  is mounted on the main spindle  2 . The roller die assembly  56  has a bearing  57  and a gear unit  58  and a top plate  59  through which extends an actuator shaft  60  which is rotated by a handle  61 . In this particular set-up one of the three clamps  31  may be locked to the degree plate  30 . 
     Referring to  FIG. 10 , when a work-piece W 2  is inserted between the two counter dies  55  and a die  70 , a small extension of the piston  8  moves the counter dies  55  to a point where the desired bend is achieved. Rotation of the handle  61  causes the roller die  70 , keyed to the die bearing  57 , to rotate to move the work-piece through the machine as it is formed into the desired radius of curvature. In this mechanism, the actuator  60  connects to a gear which drives a larger gear which is fixed to the bearing  57 . With this set-up, infinitely variable radius of curvature can be achieved in the work-piece. 
       FIG. 11  shows a variation in which an hydraulic motor  80  causes the die  70  (not shown) to rotate (via the gear train  58 ). This is of course convenient and provides a uniform speed of operation. 
     As shown in  FIGS. 12 and 13  a counter die support  100  may be mounted on each working arm  3  at any combination of the holes  22 . This supports a counter die  102  at a position with an infinite adjustment in a direction to or from the main spindle  2  axis. Adjustment screws  101  are used for this infinite adjustment, as they cause translational movement of a bronze glider plate  103  attached to a hardened round steel pin  104  at the outer end of which there is a counter die  102 . The pin  104  is inserted into the plate  103  and retained there by a pin. 
     A die  110  comprises a round die  111  with a disc having a hexagonal hole in it. These two are attached by six bolts, stopping rotation on the spindle  2 . 
     The infinitely adjustable counter die supports  100  can act asymmetrically. For example there could be fixed anvil as one counter die and a roller counter die as another, in different positions. 
     The ram  6  can be locked to the ring  30  and as a result of this, the degrees read off the degree plate are half of the value indicated as both arms  3  are travelling in opposing directions. If one arm  3  is locked to the degree plate, then both the ram  6  and the opposing working arm  3  rotate about the main spindle  2 , albeit at different speeds i.e. the ram is moving at half the degrees as the working arm. 
     This arrangement allows infinite adjustment to suit the workpiece dimensions and the desired bending angles, as shown in  FIG. 13  (which shows alternative counter dies  120 ). 
       FIG. 14  shows the support  100  being mounted on one working arm  3 , and a die  130  which is free to rotate about the main spindle  2 . There is a material hook  140  for gripping and anchoring to provide one point of the three-point bending. The main die  130  is attached to the material hook  140  and acts as one piece. That assembly is bolted to the working arm  3  by means of bolts  131 , and is free of the hex on the spindle  2  and as such is free to rotate about the main spindle  2  in conjunction with working arm  3 . 
     The hook  140  acts as one point in a three-point bending setup. The counter die tip  142  is another point in this system, and the main die  130  is the last. As the machine  1  cycles, the hook  140  (with an internal opening  141 ) retains the material which is drawn through the counter die, held by the adjustable counter die support. This process is referred to as “rotary draw bending”. 
       FIG. 15  shows a die set  150  for solid cross-sectional bar bending. A male V-shaped die  152  is mounted on the main shaft, while a female V-shaped counter die  153  slides in a frame  151  upon rotation of the working arms  3 . As the arms  3  rotate pins  155  push against a base  156  forcing it to move translationally to slide the counter die  153  within the frame  151 . 
     These are but some examples of use of the machine  1  for a very wide range of bending operations because the machine  1  is a three point bending platform, the main spindle  2  of which is an axis about which the working arms  3  rotate. 
     The working arms  3  act in pairs and by having a number of holes  22  can receive pins, which can be placed in any one of eight holes, acting as two of the points in the three point bending function. 
     Accuracy of location of the counter dies is achieved because they are on the arms  3  rotating about the spindle  2  and there is further rotation about the common joint  5 , and the arms are driven by a common drive  6 . 
     When the machine  1  is activated, the linear motion of the hydraulic piston  8  imparts its motion to the piston follower  35  and also acts on both pairs of link arms  4  simultaneously, which in turn act on both pairs of working arms  3 , rotating them about the axis of the main spindle  2 . The linkage assembly thus converts linear motion into rotary motion. Any material trapped between the counter dies on the arms  3  and the main spindle  2  die is subjected to a bending force. Force can be applied both on the push and pull strokes of the ram  6 . 
     The machine  1  allows inter alia the following functions to be carried out with the appropriate tooling:
         rotary draw bending, to 220°,   three point bending i.e. manufacture of U bolts, pipe bending up to 220° in both cases,   V-block bending of a bar, square or round or any other solid cross-section.       

     The machine provides a bending platform which enables use of specialised, customised tooling, or standard tooling for e.g. section rolling, V block, pipe bending tooling etc. It allows such use in a very efficient and simple manner, eliminating the need to have individual machines to perform each individual task, and avoiding complicated set up procedures often associated with multifunction machines while at the same time avoiding the pin and ratchet system sometimes associated with single hydraulic cylinder machines. The machine  1  has a small footprint which has the ability to take the place of a minimum of three machines, namely section rolls, pipe bender, horizontal press. 
     The main spindle  2  plays a very important role in operation of the machine. It is the coaxial point about which both working arms  3  rotate, providing equal degrees about the axis of the machine in opposing directions, the mechanical function of which lends itself suitably to bending material equal degrees about a centre line. It also serves as the attachment point for the hydraulic cylinder as well as being the anchor point for the main bending dies. Its hexagonal cross section, when required, provides a rotational lock for the main bending dies, while also providing the axis about which the machine itself rotates, independently of its degree plate and base. This feature facilitates long lengths of material to be bent and maneuvered within a confined space while eliminating material whip as the machine can rotate to align itself with the material being bent. 
     The machine also provides ease of use. When single bends are required, and the machine is set up appropriately, degrees can be read directly off the degree plate  30 . For multiple bends, once the piston  8  stroke length has been established and the clamp set accordingly, multiple bends of the same angle can be achieved using one control lever. 
     The small footprint saves valuable workspace, especially in its start position as it folds back upon itself. 
     The ability to cater for multiple tooling is very advantageous. It provides an unobstructed and level working surface on which a multitude of tooling may be mounted, allowing multiple bending functions to be carried out. These include:
         180° or more bends in flat bar, bent the hard way, used for example in traditional farmyard gates.   Custom die bending i.e. the manufacture of bow shackles etc.   Section rolling: solid and hollow cross sections.   Freeform bending: shaping scrolls, elliptical forms etc.   Straightening of bent stock and forged material.   V Block bending.   Sharp 90 degree bends etc.   Manufacture of u bolts, pipes etc. up to 220 degrees.   Bending of concrete reinforcing bars, electrical conduits, or copper pipes etc.       

     The aspect of the machine whereby all major components perform multiple roles, makes for a very efficient machine both in its function and use, given the relatively few moving parts it requires i.e. minimum wear and long life expectancy 
     All greasepoints are easily accessible and all wear components can be replaced (bronze bushes) 
     Also the machine can be manufactured in any size, and so is scalable. 
     Referring to  FIGS. 16 to 20  an alternative machine,  200 , is illustrated. Like parts are given the same reference numerals. The machine  20  has a hollow link arm pivot joint  201 , and hollow joints  202  for connection of the link arms  4  to the working arms  3 . The joints  202  have internal keyways  203 . There is a main spindle  205 . 
     A base  210  of the machine  200  has a twin-port hydraulic rotary union distributer  215  fed by an electric motor  211  and hydraulic pump  212  assembly. There is an auxiliary valve  216 . The distributer  215  feeds the spool valve  230 . The auxiliary valve  216  feeds, via flexible hoses (not shown), two hydraulic motors  220 , in turn driving the hollowed keyed shafts  203 . These drive the dies  261  in the use shown in  FIGS. 17 and 18 . 
     The machine  200  also has a spool valve  230  and there is an adjustable stop  231  on the piston follower  35 . Hydraulic lines  232  run from the spool valve  230  ( FIG. 17 ). 
     The main spindle  205  has a through-hole  245  for the ram  6 , and pressure and return hydraulic conduits  240  and  241  which feed hydraulic oil to the ram  6  and potentially other parts such as motors  220 . This reduces the number of flexible holes needed. 
     The spool valve  230  has a handle  250 . 
     In operation, when the clamp  231  is attached to the piston follower  35  and the handle  250  is moved to the left, bend, position the end of the spool is forced to the rear of the machine. As the machine cycles the piston follower  35  clamp  231  moves towards the spool valve  230  until the end of the fine adjustment stop makes contact with the end of the spool. This forces the spool back to the neutral position. This achieves an infinitely variable fixed point used for producing multiple bends of the same degree. This depends on where the clamp  231  is set on the piston follower  35 , and on where the fine adjustment is set. 
     In one example ( FIGS. 17 and 18 ), a die  260  is free to rotate on roller bearings. Dies  261  are mounted on the joints  202 . Rotational power is supplied to the dies  261  from the hydraulic motors  220 , each attached to the working arms  3  which in turn are fed via flexible hoses from the valve  216  (hoses not shown). This example use allows for section rolling of pipe but with alternative dies it could be any section such as square or rectangular. 
     In another example ( FIGS. 19 and 20 ) of use a sliding plate  270  is pivotally connected to the joint  201 . However its movement is restricted to translational only, (sliding), movement by a fixed guide tool  271  on the spindle  205  extending through a rectangular aperture  273  in the plate  270 . There is also a V-block moving tool  272  extending through the aperture  273 . This is fixed to the sliding plate  270 . This achieves a bending force between the dies  271  and  272  when the machine cycles. 
     Referring to  FIG. 21  a roller die assembly  300  comprises an hydraulic motor  301  mounted on a plate  302  and having an output shaft  303  driving a bearing  304  (shown supporting a die  305 ). The bearing has a pin  306  for engaging a hole  22  of a working arm  3 . The plate extends laterally and at its other end it supports a pin  309  on a spacer  310  arranged for engagement in another hole  22  of the same working arm  3 . The die assembly provides its own independent drive and the pin  309  engagement in the hole  22  prevents it from rotating, so all of the motor&#39;s drive is applied to the bearing  304  and hence the die  305 . 
     The die assembly  300  is particularly simple because it does not have a gear mechanism. The required speeds and torques may be applied by control of the hydraulic motor  301 . 
     It will be appreciated that if both of the working arms support a “self-drive” die assembly  300  and the main spindle supports a self-drive die assembly such as the assembly  56  then all three dies may be driven. This allows very effective and fast roller bending. 
     Referring to  FIG. 22  a machine has many parts like the machines described above, and like parts are indicated by the same reference numerals. There is a self-drive die assembly  360  on each of the working arms  3  and such a die assembly on the main spindle  2 . Each assembly  360  has a motor  361  on a plate  362  and an output shaft gear  363  drives a larger gear  364 , in turn driving a bearing  365  for a die. There is a pin  366  to prevent rotation of the overall assembly. 
     The assembly  370  comprises a motor  371  on a plate  372  driving a gear  373 , in turn driving a larger gear on a bearing  374 . 
     Referring to  FIG. 23  a machine  400  also has many parts like those of the embodiments above and like parts are given the same reference numerals. In this case a handle  401  provides drive via a shaft  402  to a gear  404  through a plate  403 . The (small) gear  404  drives a larger gear  405  on a die bearing  406  for a die  407 . Each working arm  3  supports a die assembly with a gear  410  intermeshed with the gear  405 , as also shown in plan in  FIG. 23 . Each gear  410  is on a bearing  411  for a die  412 . 
     The machine  400  has the advantage that the dies may apply a particularly small radius bend and do so without slippage of the dies. Slippage has in the past been a particular problem for roller bending with a small radius of curvature. 
     It will be appreciated that the invention in the various embodiments achieves simplicity and cost-effectiveness due to the small number of parts. For example, the die support shaft performs the multiple roles of supporting the main die and of providing a pivot joint for the working arms supporting the counter dies. Moreover, it also guides the ram orientation in a central and symmetrical manner for bending accuracy. There is also excellent versatility because of the range of mutual angles through which the dies may be driven, the choice of counter die locations on the working arms, and the possibility of having die supports on the working arms and also of self-driving the dies. 
     The invention is not limited to the embodiments described but may be varied in construction and detail. For example, the link arms may be indirectly pivotally connected to each other, such as via a short bar. This, however, creates an additional pivot joint and might restrict freedom of movement of the link arms. 
     The translational drive component may be provided by any other suitable drive such as a screw. 
     Where an individual die drive is provided (such as the drive  220 ), this may be, additionally or alternatively, for the main die rather than just for the counter dies. 
     There may be built-in electronic and/or optical sensors for the ram, rather than a piston follower arrangement.