Patent Publication Number: US-7721582-B2

Title: Bending machine for rod-shaped workpieces made from wire, tubular material or the like

Description:
RELATED APPLICATION 
   The current application claims the benefit of priority to European Patent Application No. 06 007 400.2 filed on Apr. 7, 2006. Said application is incorporated by reference herein. 
   FIELD OF THE INVENTION 
   The invention relates to a bending machine for rod-shaped workpieces made from wire, tubular material or the like. 
   BACKGROUND OF THE INVENTION 
   In the prior art, different bending machines for bilateral processing of workpieces cut to length are known. 
   DE 3922326 C2 describes a bending machine comprising two bending heads mounted to robot arms, wherein up to four axes of rotation are present for positioning the tool on the workpiece. Each robot arm has its own guide assigned to it, allowing said robot arm to be displaced parallel to the workpiece. Between the guideways of the robot arms, a gripping unit is provided for fixing the respective workpiece to be processed, which gripping unit can be lowered, in which case a bending tool then functions as gripping means. The use of bending robots for bending the workpiece to be shaped is very complex, so that due to the workpiece to be processed being held only at its center or even only due to the fixation of the workpiece when lowering it, undesired vibrations may occur at the bending tool in the longitudinal direction of the workpiece, which has an unfavorable influence both on the bending accuracy as well as on the possible speed of the bending operations and, thus, on the performance of the machine. 
   A bending device is known from DE 4300311 C2, which bending device comprises one or more gripping units that can be displaced in one plane, said gripping units transporting the workpiece to be processed between parallel bending stations, each of said bending stations carrying out one single bending operation. During bending itself, the tool is fixed by the clamps of the bending tool of the respective bending station. In this case, the bending heads are fitted on a vertically displaceable table so as to enable transport of the workpieces without vertically moving the gripping units. This known machine is very complex in terms of its overall structure and does not allow the processing of wire directly from the coil. 
   DE 19630023 A1 describes a bending system comprising a plurality of bending stations in which a workpiece can be processed first on one side and then on the other or, in the case of bending in one plane, on both sides at the same time. In this case, a plurality of gripping units are provided to convey the workpiece between the individual bending stations, which grippers are also used to rotate the workpieces. The bending heads are arranged for displacement parallel to the workpiece axis. All gripping units are mounted to a portal. This known bending machine also has a very complex structure, which applies particularly to the arrangement of the gripping units on a portal construction. This known bending machine also does not enable processing of wire drawn directly from the coil. 
   The bending machine known from DE 20 2004 011 947 U1 also serves to process elongated workpieces in a plurality of stations. In this case, each station comprises a central gripping unit and two bending heads mounted laterally thereof, which are displaceable on a common bed guide as is the gripping unit. In addition, a pivotable transfer device is provided by which the workpiece can be pivoted from the first processing station to the second, parallel processing station. The transfer device may be the gripping unit at the same time. This known machine works serially from out of a magazine and likewise does not allow the processing of wire directly from the coil. 
   SUMMARY OF THE INVENTION 
   In view of the above, it is an object of certain embodiments of the invention to propose a new bending machine of the above-mentioned type, which is also suitable to process wire from a coil, has a comparatively simple structure, is particularly flexible in use and allows a high production capacity. 
   According to certain embodiments of the invention, this object is achieved by a bending machine for rod-shaped workpieces made from wire, tubular material or the like, wherein a machine frame is provided with at least one bending station thereon comprising two bending units, each of said bending units comprising a bending head with a bending head housing and with a bending tool as well as an auxiliary gripper arranged on the bending head housing so as to be pivotable perpendicular to the longitudinal axis of the frame and an associated gripping unit which is spaced apart from the bending head, as viewed along the longitudinal axis of the frame, is pivotable perpendicular to the longitudinal axis of the frame and is displaceable on a guide in the direction of said axis. Further, the two bending heads of each bending station are arranged adjacent to each other with their auxiliary grippers facing each other and are positioned between the two gripping units such that each bending head—viewed in the direction of the frame&#39;s longitudinal axis—is mounted between the other bending head and its associated gripping unit. 
   The bending machine according to certain embodiments of the invention is very flexibly usable, because it permits not only the processing of rod-shaped workpieces from out of a magazine, but also the processing of material from a coil. The arrangement of one bending station with two bending units according to certain embodiments of the invention allows both ends or sides of a cut-to-length workpiece to be bent one after the other into a desired shape in a bending station. The arrangement of at least two bending stations (that is, one on either side of the machine frame), each comprising a pair of bending heads mounted thereto with an associated gripping unit, makes it possible to simultaneously process as many as four workpieces in different stations, which is a considerable improvement in efficiency, with each workpiece cut to length being processed in an alternating manner in the first and then in the second bending unit of the respective bending station. Since each bending unit fixes the respective workpiece itself, it is possible that, after processing of the workpiece in the first bending unit and transfer to the second bending unit of the same bending station, a new workpiece can be received and processed again in the other bending station at the same time as and parallel to the processing of the transferred workpiece. 
   The fact that, due to their pivotability perpendicular to the longitudinal axis of the frame in certain embodiments, the gripping units of each bending station seize the workpieces in an orientation parallel to said axis allows the workpieces to be supplied centrally in the longitudinal direction of the frame (and oriented along said axis) between the bending stations arranged on both sides of the machine frame. This allows the feeding, straightening and separation of the wire from the coil to be effected by a preceding unit, with the workpiece that has been cut to length being present immediately after cutting in a position suitable for seizing between the bending stations. 
   However, the bending machine according to certain embodiments of the invention may also be operated without such a feeding and straightening unit as well as without such a cutting unit, in which case workpieces already cut to length would have to be provided in a magazine, e.g. laterally of the machine frame. The arrangement of the bending stations with their bending units also allows the bending machine according to the invention to seize the individually provided workpieces from the magazine and to transfer them into the respective bending unit without any problem. 
   Similarly, it is also possible, for workpieces having the same shape to be manufactured on one side of the bending machine in the respective bending station, and for other workpieces having a different shape (for example, also having a different length) to be manufactured on the other side of the frame so that simultaneous processing of different workpieces is possible using the bending machine according certain embodiments of the invention. 
   A further increase in the flexibility of use of the bending machine according to certain embodiments of the invention can also be achieved if two or even more bending stations are arranged on either side of the frame&#39;s longitudinal axis, in which case, for example, the same workpieces can be processed at all the bending stations of the respective bending machine, thus further increasing the production capacity of the machine. However, it would also be conceivable to bend in each bending station of such a bending machine a workpiece that is to have a different shape, so that even simultaneous bending of a plurality of different workpieces could take place. 
   Of course, in certain embodiments each of the two gripping units of a bending station can have its own guide mounted to the bending machine according to the invention. However, it is particularly preferred if both gripping units of a bending station are displaceable along the same guide. 
   The guide of the gripping units may be provided in any suitable manner. In particularly preferred embodiments, however, each guide for the gripping units of a bending station consists of two guideways, in particular two guide rails, which are parallel to each other as well as to the frame&#39;s longitudinal axis on the machine frame. If more than one bending station is provided on either side of the machine frame in a bending machine according to an embodiment of the invention, it is particularly preferred for all gripping units of all bending stations on the same side of the bending machine to be able to be displaced along the same guide rails on the machine frame. This provides for not only a simplification of the overall structure, but particularly also a precise alignment of the adjusting directions of the gripping units of a bending station relative to one another. 
   In a bending machine according to certain embodiments of the invention, each auxiliary gripper advantageously comprises a supporting arm which is pivotably supported directly on the side of the bending head housing of the associated bending head, said supporting arm again preferably comprising, at its protruding end, a gripping arrangement that is radially displaceable with respect to its pivoting axis and is provided with two clamps for seizing the rod-shaped workpiece to be fed to the bending tool for bending. This results in a relatively simply structured, but very efficient overall constructive arrangement for the auxiliary gripper. 
   It is further advantageous if each gripping unit in the bending machine according to certain embodiments of the invention also comprises a pivotable lever arm which carries at its end region facing away from its pivoting axis a gripping arm that is in turn mounted so as to be pivotable about a further pivoting axis and comprises two gripping arrangements spaced apart from each other in the longitudinal direction of the frame&#39;s longitudinal axis for seizing a rod-shaped workpiece. In this case, the pivoting axes of the lever and gripping arms of each gripping unit are preferably parallel to one another. This also results in a relatively simple construction of the individual gripping unit. 
   Each gripping unit is preferably accommodated, with its associated drives, on a holding plate which is in turn displaceably fitted on the guide rails of the machine frame. 
   A further embodiment of the bending machine according to the invention also provides that, although each bending head housing is securely attached to the machine frame, the bending tool is displaceable, in the direction of its axis of rotation, relative to the bending head housing. 
   In a bending machine according to certain embodiments of the invention, the machine frame is advantageously provided, at its upper portion to which the bending stations are attached, with a machine bed that is substantially an isosceles trapezoid in cross-section, with the bending stations on both sides of the frame&#39;s longitudinal axis respectively being mounted to the oblique sides of the machine bed. This provides a particularly advantageous overall arrangement which is also relatively space-saving and, at the same time, allows easy and unhindered access to the individual elements of the bending stations. 
   The holding plates with the gripping units fitted thereon may be displaced along the guide rails in any suitable manner. However, it is particularly preferred if the gripping units are each displaceable along the guides via a rack-and-pinion drive, in which case the use of a single rack over the entire length of the guides on one side of the frame is sufficient to displace all holding plates with their gripping units. 
   Moreover, it is particularly preferred that in the bending machine both the bending heads with the auxiliary grippers and also the gripping units in a bending station are structurally identical. 
   It is similarly advantageous also if respective pairs of bending stations arranged opposite each other with respect to the frame&#39;s longitudinal axis are identical in design. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail below, principally by way of example, with reference to the drawings, wherein: 
       FIG. 1  shows a perspective view (an oblique frontal top view) of a bending machine according to an embodiment of the invention with a preceding feeding and straightening unit as well as with cutting and guiding units; 
       FIG. 2  shows a top view of the bending machine of  FIG. 1 ; 
       FIG. 3  shows an end view of a bending machine according to  FIG. 1  from the machine&#39;s end side (viewed in the longitudinal direction of the machine); 
       FIG. 4  shows a perspective top view of a bending station of the bending machine according to  FIG. 1 ; 
       FIG. 5  shows an enlarged perspective view of a gripping unit of the bending machine according to  FIG. 1 , said unit being mounted to a holding plate, and 
       FIG. 6  shows a perspective (enlarged) view of a detail of a bending head with a bending head housing and an auxiliary gripper of the machine according to  FIG. 1 , said gripper being pivotable on the bending head. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a bending machine  10  for processing wire  12  from a coil according to an embodiment of the present invention. On the wire input side, the bending machine  10  is provided with an infeed and straightening unit  14 , following which there is arranged a machine frame  16  comprising at its upper region a machine bed  18  whose cross-section is substantially an isosceles trapezoid, as is well-recognizable particularly from the (only schematically drawn) representation of the machine frame  16  in the end view of the bending machine  10  in  FIG. 3 . 
   The bending machine  10  has a longitudinal frame axis M-M, with a first bending station  20  (located at the front in the representation of  FIG. 1 ) and a second bending station  22  (located at the rear in the representation of  FIG. 1 ) being mounted to the machine bed  18  opposite each other on both sides of the frame&#39;s longitudinal axis M-M. 
   Reference is made first to the infeed and straightening unit  14 , which comprises at least one infeed module  24  including a pair of infeed rollers  26  for feeding wire  12  from a coil (not shown). In addition, a straightening module  28  is provided, which may consist of a conventional rotating straightening body or also of a straightening apparatus with rollers and which straightens the wire  12  by bending in all planes. 
   Arranged following the straightening module  28  are a further infeed module  30 , comprising a pair of infeed rollers  32 , and a length-measuring unit  34 , the latter being engageable with the wire  12  so as to determine the exact feed length. 
   After the infeed and straightening unit  14 , the wire  12  passes through a cutting and guiding unit  36 , with the wire being supported over its entire length by a plurality of guide elements  38  spaced apart on the machine bed  18  in the longitudinal direction of the frame. 
   At a suitable location between these guide elements, namely following the second guide element  38  (as viewed in the feed direction R of the wire  12 ) after the output point of the wire from the infeed and straightening unit  14  in the depicted bending machine  10 , a cutting module  40  is mounted to the machine bed  18  such that it cuts off the wire  12  after a corresponding infeed length and thereby produces an elongated workpiece  42  cut to length as the initial workpiece for the subsequent bending operations. The position of the cutting module  40  is suitably selected at a site which is located in front of the entrance of the cut-to-length workpiece  42  between the bending stations  20  and  22  so that the workpiece  42  is easily seized there directly by a gripping unit of a subsequently arranged bending unit of a bending station  20  or  22 , respectively, after the cutting operation and without further transport in the longitudinal direction of the frame and can then be transferred to one of the bending stations  20  or  22 , respectively. 
   In the bending machine  10  of  FIG. 1 , the first bending station  20  and the second bending station  22  have an identical design, so that only the first bending station  20  (namely the bending station which is at the front, i.e. facing the viewer, in  FIG. 1 ) will be described in more detail, because its description likewise applies to the second bending station  22  as well. 
   The first bending station  20  comprises two bending units  44  and  46  and the opposite second bending station  22  comprises two bending units  48  and  50 . 
   The first bending unit  44  of the bending station  20  comprises a gripping unit  52  and a bending head unit  54  with an auxiliary gripper  56  mounted thereto and pivotable in a plane perpendicular to the frame&#39;s longitudinal axis M-M. 
   The other bending unit  46  of the bending station  20  in turn also comprises a gripping unit  58 , a bending head unit  60  and an auxiliary gripper  62  mounted to the latter and pivotable in a plane perpendicular to the frame&#39;s longitudinal axis M-M. 
   Each of the two gripping units  52  and  58 , respectively, is fitted on a holding plate  64  or  66 , respectively. Both holding plates  64 ,  66  are displaceable on a guide extending in the frame&#39;s longitudinal direction M-M on the machine bed  18  (in the direction Z in  FIG. 1  and  FIG. 6 ), said guide consisting of two guideways in the form of suitably provided guide rails  68 ,  70  that are parallel to one another as well as to the frame&#39;s longitudinal axis M-M. 
   The displacement of the holding plates  64 ,  66  is effected along the guide rails  68 ,  70  via a toothed rack  72 , in a motor-driven manner and parallel to the workpiece  42  cut to length. 
   The two bending head units  54  and  60 , whose construction is shown in detail in the enlarged representation of  FIG. 6  (which will be discussed in detail below), are in turn securely attached to the pair of guide rails  68 ,  70  and are not displaceable relative to the latter. As shown in detail in  FIG. 6 , only the two auxiliary grippers  56  and  62  are laterally mounted to the bending head housing  84  in a pivotable manner (in the pivoting direction T within a pivoting plane perpendicular to the frame&#39;s longitudinal axis M-M). 
   The gripping unit  52  on the holding plate  64  cooperates with the bending head unit  54  and its laterally associated auxiliary gripper  56  in connection with the first bending unit  44 , while the other gripping unit  58  cooperates with the bending head unit  60  and its laterally mounted auxiliary gripper  62  in connection with the second bending unit  46 . 
   In analogy, this also applies to the second bending station  22  arranged opposite the first bending station  20  and to the bending units  48  and  50  comprised by the former. 
   The top view shown in  FIG. 2  of the bending machine  10  according to  FIG. 1  again clearly depicts the arrangement of the bending stations  20  and  22  effected on both sides of the frame&#39;s longitudinal axis M-M (which coincides with the orientation of the fed wire  12  in the top view) and their respective two bending units  44 ,  46  (bending station  20 ) and  48 ,  50  (bending station  22 ). 
   It is recognizable in FIGS.  1  and  3 —the latter showing a view of the bending machine  10  from the end side thereof (i.e. from the right-hand end in FIG.  1 )—that the bending stations  20  and  22  exhibit a mirror-symmetrical arrangement of the individual elements of both bending stations  20 ,  22  with respect to each other relative to the vertical longitudinal central plane of the machine frame  16 . 
   First of all, however, reference is made to the representation of  FIG. 5  which shows the structure of a gripping unit, namely that of the gripping unit  58  of  FIG. 1 , in an enlarged perspective view. 
   The gripping unit  58  comprises a lever arm  74  which is pivotable in the direction of rotation Y about an axis of rotation D that is parallel to the direction of displacement Z. The pivoting movement is caused by a motor  76  to which the lever arm  74  is connected. 
   At its end region facing away from the axis of rotation D, the lever arm  74  supports a gripping arm  78  such that it is pivotable in the direction of rotation X about an axis of rotation E that is parallel to the axis of rotation D of the lever arm  74 . The gripping arm  78  which also extends in the direction of the axis of rotation E comprises at its lower surface two gripping arrangements  80 , which are spaced apart by a distance a and each of which comprises two clamps  82  that are arranged perpendicular to the axis of rotation E and are mutually displaceable for seizing the workpiece  42 , as shown in detail in  FIG. 5  to which reference is made. 
   The gripping unit  58  is fitted on a holding plate  66  which also accommodates the motor  76  as well as other drives required to effect the various movements. 
   By pivoting the lever arm  74  in the direction of rotation Y, the gripping unit  58  can be pivoted towards the workpiece  42 , which has been centrally fed between the two bending stations  20  and  22 , in order to seize said workpiece  42  with the gripping arm  78 , by means of the two gripping arrangements  80 , following which the workpiece  42  can be transferred, by pivoting in the opposite direction, to the region of the bending station  20  in order to effect bending operations there. 
   However, it is likewise possible that a workpiece  42  already partially bent in the bending station  20  could either be deposited laterally of the machine frame  16  by further pivoting of the gripping unit  58  following the bending operations or, in the case of pivoting in the opposite direction, the workpiece  42  could be transferred, for example, to the opposite bending station  22 , picked up there by a gripping unit of that bending station and then subjected there to further shaping by bending. 
   Thus, the entire assembly of the gripping unit  58  with holding plate  66  comprises two axes of rotation D and E and is displaceable in the direction of Z. However, in special cases of use it could also be convenient to provide the gripping unit  58  such that the gripping arm  78  is in turn rotatable also about a further (third) axis of rotation which passes through the axes of rotation D and E and is perpendicular to said axes of rotation. This makes it possible to transfer a workpiece  42  also in an initial position or in an orientation which is not parallel to the frame&#39;s longitudinal axis M-M. 
   Reference will now be made to the representation of  FIG. 6  showing, in an enlarged oblique perspective view (an oblique frontal top view), the construction of a bending head unit with an associated auxiliary gripper, in this case the bending head unit  60  and the auxiliary gripper  62 , which cooperate with the gripping unit of  FIG. 6  in connection with the first bending unit  44  of the first bending station  20 . The bending head unit  60  comprises a bending head housing  84  to which a bending tool  86  is attached which consists of a central bending mandrel  88  that is in turn rotatable in the direction of rotation U and of an associated bending pin  90  that is arranged concenctrically to the mandrel  88  and is rotatable in the direction of rotation V. 
   An auxiliary gripper  62  is mounted to the bending head housing  84  immediately laterally of the latter, said auxiliary gripper  62  being pivotable about a pivoting axis F in a direction of rotation T and consisting of a supporting arm  92 , whose end facing away from its pivoting axis F is provided with a gripping arrangement  94  comprising two mutually displaceable clamps  96 . The gripping arrangement  94  including the clamps  96  is radially displaceable in the direction S (i.e. in the longitudinal direction of the supporting arm  92 ) with respect to the pivoting axis F. The pivoting axis F of the supporting arm  92  extends parallel to the frame&#39;s longitudinal axis M-M and is located at a point on the side of the bending head housing  84  such that, when the supporting arm  92  is aligned parallel to the axis of rotation of the bending tool  86  (bending mandrel  88  and bending pin  90 ), the workpiece  42  to be processed and held between the clamps  96  has an orientation that is proper for reception within the bending tool. 
     FIG. 4  shows an oblique perspective view of a portion of the bending machine  10  which substantially comprises the bending station  20 . 
     FIG. 4  shows the condition of the machine in which the feed wire has just been cut by the cutting module  40  (the wire arranged preceding the cutting module  40  in the infeed direction has been omitted), thereby producing a workpiece  42  cut to length (in this case, a wire section having a predetermined length), which is initially held by various guide elements  38  arranged with an offset in the longitudinal direction. 
   The gripping unit  58  has now been pivoted such that the clamps  82  at the bottom surface of the gripping arm  78  can seize the elongated workpiece  42  at its front end region at two mutually offset points and transfer it to the processing zone of the bending station  20  by pivoting in the direction Y. If required or desired, the auxiliary gripper  62  of the bending head unit  60  cooperating with the gripping unit  58  may also be pivoted towards the workpiece  42 , which can additionally be seized also by the clamps  96  of said auxiliary gripper  62  at a further point and then transferred to the bending station  20  together with the gripping unit  58  by being pivoted back. 
   As is also clearly shown in  FIG. 4 , the bending head units  54  and  60  of the first bending station  20 , which are both securely fixed to the guide rails  68 ,  70  of the machine bed  18 , have different orientations with respect to each other so that their bending tools have bending axes that are inclined towards each other. 
   The bending machine  10  shown in the Figures operates in the manner described below, shown with reference to a continuously fed wire  12 : 
   As  FIG. 1  shows, the wire  12  is drawn from a coil (not shown) through the infeed module  24  via the infeed rollers  26  and is fed to the straightening module  28 . The further infeed module  30  arranged following the straightening module  28  pulls the wire  12 , just straightened, out of the straightening module  28  and feeds it via the further pair of infeed rollers  32  to the subsequently arranged length-measuring unit  34 . From the length-measuring unit  34 , the wire  12  is further fed to the cutting and guiding unit  36 . As soon as the desired length of wire has been detected by the length-measuring unit  34 , the infeed modules  24  and  30  are stopped, and the cutting module  40  is actuated, thereby producing a workpiece  42  cut to length, as shown in  FIG. 4 . 
   Displacing the holding plate  66  of the gripping unit  58  in the Z direction and pivoting the lever arm  74  and the gripping arm  78  about their respective pivoting axes D and E allows the gripping arrangements  80  on the gripping arm  78  to be moved into the path of the cut-to-length workpiece  42  supported on the guiding elements  38  (cf.  FIG. 4 ) and allows the workpiece  42  to be seized at its end region there (cf.  FIG. 4 ). If a long workpiece  42  is to be processed—as already outlined above—the auxiliary gripper  62 , which cooperates with the gripping unit  58  and is provided at the bending head unit  60 , may also be pivoted towards the workpiece  42  and likewise seize the latter by the clamps  96  of the auxiliary gripper  62  so as to prevent, for example, the workpiece  42  beginning to vibrate when pivoting back to the bending head unit  60  of the bending unit  46 . 
   The gripping unit  58  and the auxiliary gripper  62  then pivot the workpiece  42  into the region of the bending head unit  60 . 
   As a result of the bending tools&#39; movements in the directions U, V and W as well as due to the movement of the holding plate  66  in the Z direction and of the gripping unit  58  about the pivoting axes D and E, one side of the cut-to-length workpiece  42  can be provided with bends in different planes. 
   In order to enable processing of the other side of the workpiece  42 , the gripping unit  52  and the auxiliary gripper  56  of the other bending unit  44  then pivot towards the bending head unit  60 , where they pick up the previously bent workpiece  42 , following which they pivot the latter towards the bending head unit  54 . There, the second portion of the workpiece  42  is then bent and, as soon as bending of the workpiece  42  is completed, the workpiece  42  can then be deposited laterally of the bending machine  10 , e.g. on a conveyor belt or the like, by the gripping unit  52 . 
   After the workpiece  42  has been transferred from the bending unit  46  to the other bending unit  44 , a new workpiece  42  can be fed to the bending unit  46 . 
   During processing of a workpiece  42  in the bending unit  46 , the infeed modules  24  and  30  are actuated again, and a second workpiece  42  cut to length is produced. This workpiece is then processed in the opposite second bending station  22 , for which purpose the gripping unit arranged there opposite the gripping unit  58  picks up this second workpiece  42  and pivots it into the bending zone of the bending head unit located opposite the bending head unit  60 . 
   The infeed and straightening unit  14  then alternately feeds the first bending station  20  (front) and the second bending station  22  (rear), the workpiece  42  being bent in both bending stations first in the bending unit  46  or  50 , respectively, and then in the bending unit  44  or  48 , respectively. 
   The construction of the bending machine  10  enables its extremely flexible use: 
   For instance, similar workpieces can be bent in the bending stations  20 ,  22 , which provides for almost double the production capacity as compared to a simple machine. It is also possible to produce different parts on both sides of the machine in both bending stations  20 ,  22  and also from wire sections having different lengths. 
   The bending machine  10  can also be operated without the infeed and straightening unit  14 , e.g. if cut-to-length workpieces are provided in a magazine. In this case, processing would be effected in a serial manner and the respective workpiece  42  would be shaped in up to four processing stations (bending units). A transfer from the first bending station  20  to the second bending station  22  is possible without any difficulty using the gripping units  52  and  58 . 
   It is also possible to arrange a plurality of bending stations behind each other on either side of the bending machine  10  so that, accordingly, more than four bending units are realized on either side. The gripping unit  58  is designed such that a transfer to a further bending machine (not shown in the Figures) placed next to the bending machine  10  could be effected. 
   All processes of the entire machine are conventionally controlled by a central program control (not shown in the Figures). 
   The gripping arms of all gripping units  52 ,  58  etc. are preferably pivotable through 360°, whereas the lever arms of the gripping units  52 ,  58  etc. as well as the supporting arms of the auxiliary grippers  56 ,  62  etc. are pivotable through 180°. 
   The bending head housings  84 , etc. of the individual bending head units  60 , etc. comprise the drive for the bending pins, the drive for the bending mandrels as well as the drive for displacing the actual bending head (bending tool) in the direction W.