Abstract:
In order to improve a material-working machine for flat material parts, comprising a machine frame, processing tools held on the machine frame, a supporting unit, on which the flat material part can be placed for feeding to the processing tools in at least one main feed direction, and a controller for controlling a processing sequence using the processing tools, in such a way that it can be operated in an ergonomically favorable manner, it is proposed that the supporting unit extends in the main feed direction from a region toward the tool to a region remote from the tool and that the extent between the region toward the tool and the region remote from the tool is variably adjustable.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims the benefit of German Application No. 10 2006 047 109.1, filed Sep. 27, 2006, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a processing machine for flat material parts, comprising a machine frame, processing tools held on the machine frame, a supporting unit, on which the flat material can be placed for feeding to the processing tools in at least one main feed direction, and a controller for controlling a processing sequence using the processing tools. 
         [0003]    Material-working machines of this type are known from the prior art. 
         [0004]    They have the problem that, when a supporting unit of this type is provided, operating the material-working machine is ergonomically unfavorable. 
         [0005]    It is therefore an object of the invention to improve a processing machine of the generic type in such a way that it can be operated in an ergonomically favorable way. 
       SUMMARY OF THE INVENTION 
       [0006]    This object is achieved according to the invention by a processing machine of the type described at the beginning by the supporting unit extending in the main feed direction from a region toward the tool to a region remote from the tool and by the extent between the region toward the tool and the region remote from the tool being variably adjustable. 
         [0007]    The variable adjustability of the supporting unit provides the possibility for an operator to be able to operate the processing machine from the sides of the supporting unit, since, in the case of flat material parts of a small extent in the main feed direction, the extent of the supporting unit can be correspondingly reduced and, on the other hand, in the case of flat material parts of a great extent in the main feed direction, the extent of the supporting unit can be increased. 
         [0008]    In principle, it is possible to adjust the extent of the supporting unit manually. However, a particularly advantageous solution provides that the supporting unit is provided with an adjusting drive adjusting its extent between the region toward the tool and the region remote from the tool. 
         [0009]    An adjusting drive of this type could also be manually controllable. 
         [0010]    A particularly advantageous solution provides that the adjusting drive can be controlled by the controller. 
         [0011]    This provides the possibility of adjusting the extent of the supporting unit already on the basis of the data available to the controller for the working operations on the flat material part. 
         [0012]    A particularly advantageous solution provides that the extent of the supporting unit in the main feed direction can be adjusted by means of the controller to correspond to an extent in the main feed direction of the flat material part to be processed. 
         [0013]    This provides the possibility of always adjusting the supporting unit in such a way that the flat material part to be processed can be favorably placed on it without an operator having to actively intervene and, on the other hand, the variable adjustment of the supporting unit provides the operator standing at the sides of the supporting unit, in particular in front of the region remote from the tool, with the possibility of appropriately handling the flat material part. 
         [0014]    In particular, the controller is formed in such a way that it controls this extent of the supporting unit in the main feed direction in such a way that the flat material part to be processed can be placed fully on the supporting unit in the main feed direction. 
         [0015]    If the flat material part is also to be positioned by the supporting unit exactly in relation to the material-working tools, the supporting unit is preferably provided with stop elements. 
         [0016]    These stop elements could in principle be disposed independently of the means for adjusting the extent of the supporting unit. 
         [0017]    However, a particularly advantageous solution provides that the supporting unit is provided in the region remote from the tool with stop elements for positioning the flat material part. 
         [0018]    In principle, the stop elements could in this case also be adjustable relative to the region remote from the tool and independently of the position of the same. 
         [0019]    However, a particularly advantageous solution provides that the stop elements are disposed in a positionally fixed manner in relation to the region remote from the tool and that positioning of the stop elements is effected by variation of the extent of the supporting unit in the main feed direction. 
         [0020]    In this respect, the variation of the extent of the supporting unit in the main feed direction may be used not only to optimize the supporting possibility for the flat material but at the same time be used to position the stop elements at an appropriate distance from the processing tools, so that the position of the flat material can be predetermined exactly by the stop elements, and consequently the adjustability of the region remote from the tool by the controller offers numerous advantages. 
         [0021]    It is particularly advantageous in this respect if a number of stop elements at different distances from the processing tools are provided at the end region remote from the tool. 
         [0022]    These multiple stop elements provide the possibility of reducing the adjusting displacement for the position of the stop elements, since different basic distances from the processing tools can already be predetermined by using the different stop elements. 
         [0023]    A particularly advantageous solution in this respect provides that the various stop elements can be individually activated by the controller, so that the stop element that is the most advantageous for the processing is already activated by the controller and all that is then required is for the position of this stop element with respect to the processing tool to be finely adjusted by moving the region remote from the tool. 
         [0024]    In principle, it is also conceivable to provide the entire processing machine with a supporting unit that is variably adjustable in the main feed direction. 
         [0025]    However, in the case of individual processing operations, in particular for the handling of the flat material parts by an operator, it is advantageous if a supporting device that is invariable with respect to its extent in the main feed direction is disposed in a transverse direction with respect to the main feed direction on one side of the adjustable supporting unit. 
         [0026]    An invariable support of this type can be favorably used in particular for feeding flat material parts to the supporting unit. 
         [0027]    A further advantageous solution provides for a supporting device that is invariable in the main feed direction to be disposed on both sides of the variable supporting unit. 
         [0028]    In the simplest case, supporting devices of this type may be formed as conventional supporting tables for flat material parts. 
         [0029]    No further details have been provided so far with regard to the structural form of a supporting unit that is variably adjustable in the main feed direction. 
         [0030]    So, an advantageous solution provides that the variable supporting unit has a cross member disposed in the region remote from the tool and extending transversely in relation to the main feed direction. 
         [0031]    A cross member of this type consequently defines the position of the region remote from the tool in a simple way. 
         [0032]    In order to guide this cross member adjustably in the main feed direction, it is preferably provided that the cross member is guided on lateral guides extending in the main feed direction. 
         [0033]    The guides in this case lie for example laterally of the supporting region defined by the variable supporting unit. 
         [0034]    In order to be able to move the cross member in the main feed direction, it is preferably provided that the cross member is displaceable in the main feed direction, driven by the adjusting drive. 
         [0035]    In this respect, it would be conceivable for example to dispose the adjusting drive in a stationary manner. 
         [0036]    A structurally particularly simple and advantageous solution provides that the adjusting drive is disposed on the cross member, and consequently can be moved along with the cross member. 
         [0037]    Furthermore, no further details have been provided in connection with the explanation so far of the supporting unit according to the invention as to how the supporting unit is to be formed between the region toward the tool and the region remote from the tool. 
         [0038]    In principle, it would be conceivable not to provide any additional supports for the flat material parts between the two regions. 
         [0039]    In order, however, to facilitate the handling of the flat material parts, in particular to prevent one of the flat material parts from falling through between the region toward the tool and the region remote from the tool, it is preferably provided that intermediate supporting elements are disposed between the region remote from the tool and the region toward the tool. 
         [0040]    Intermediate supporting elements of this type could, for example, be constituted by separate devices between the region toward the tool and the region remote from the tool—depending on the distance between them. 
         [0041]    However, a particularly advantageous solution provides that the intermediate supporting elements are coupled with a movement of the region remote from the tool in the main feed direction. 
         [0042]    A solution that can be structurally realized particularly suitably provides that the intermediate supporting elements can be moved into various positions between the region toward the tool and the region remote from the tool when there is movement of the region remote from the tool in the main feed direction. 
         [0043]    The intermediate supporting elements could for their part be movably guided on guides especially provided for them. 
         [0044]    However, it is structurally advantageous if the intermediate supporting elements are guided on the guides for the cross member. 
         [0045]    Guidance of this type may provide that guides especially provided for the intermediate supporting elements are held on the guides for the cross member or that the intermediate supporting elements are directly guided themselves in the guides for the cross member. 
         [0046]    In particular whenever invariable supporting devices are provided laterally of the supporting unit in the main feed direction, it is advantageous when providing a cross member if the cross member extends up to and into the invariable supporting devices. 
         [0047]    In this respect, the cross member may be used in a wide variety of ways within the invariable supporting devices. 
         [0048]    One possibility provides that the cross member carries stop elements in the region of the invariable supporting devices, so that variably adjustable stop elements are also available in the region of the invariable supporting devices, in order to position the workpiece exactly. 
         [0049]    No further details have been provided in connection with the explanation so far of the individual features of the material-working machine according to the invention. So, in particular, the material-working tools could be, for example, punching or bending and pressing tools. 
         [0050]    A particularly advantageous solution provides that the processing tools are pivoting bending or folding tools for flat material parts. 
         [0051]    In particular, it is advantageous in this respect if the processing tools are supported by a pivotable folding beam as well as an upper beam and a lower beam for clamping the flat material part in place. 
         [0052]    In particular in the case of folding with a folding beam, safety requirements demand that, wherever possible, an operator must not be allowed in the region of the pivotable folding beam. 
         [0053]    For this reason, the solution according to the invention proves to be particularly advantageous in the case of folding, since it provides the possibility of allowing the operator to operate, monitor and control the processing machine from the side of the region remote from the tool. 
         [0054]    In this case, it is advantageous for safety reasons if the folding beam can be moved in a bending space protected by a housing. 
         [0055]    In this case, it is therefore particularly advantageous if an operating side of the processing machine is provided on a side of the machine frame that is toward the supporting unit. 
         [0056]    For example, it is provided in this case that the machine frame carries an operating unit for the controller on a side toward the supporting unit. 
         [0057]    However, it would also be conceivable for the supporting unit itself to carry the operating unit for the controller. 
         [0058]    The operator unit is preferably disposed in such a way that it is accessible in an ergonomically favorable manner for an operator standing in front of the region of the supporting unit that is remote from the tool, that is to say is within reach of the operator standing at this location. 
         [0059]    It is possible for the processing machine to be operated in an ergonomically particularly favorable manner if an operating element that can be moved along with the region remote from the tool and with which, for example, the individual processing operations can be initiated, is provided for an operator. 
         [0060]    Further features of the invention are the subject of the following description and the graphic representation of several exemplary embodiments. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0061]      FIG. 1  shows a perspective representation of a material-working machine according to the invention with a supporting unit in an intermediate position between the minimum extent and the maximum extent; 
           [0062]      FIG. 2  shows a perspective representation of the processing machine with the supporting unit at the minimum extent; 
           [0063]      FIG. 3  shows a cross-section through the first exemplary embodiment of the processing machine according to the invention at the maximum extent of the supporting unit; 
           [0064]      FIG. 4  shows a partial representation of the first exemplary embodiment of the supporting unit according to the invention with cross members and intermediate cross members; 
           [0065]      FIG. 5  shows a section along line  5 - 5  in  FIG. 4 ; 
           [0066]      FIG. 6  shows a section along line  6 - 6  in  FIG. 5 ; 
           [0067]      FIG. 7  shows a representation similar to  FIG. 4  at the minimum extent of the supporting unit; 
           [0068]      FIG. 8  shows a perspective representation similar to  FIG. 4  in the case of a second exemplary embodiment of the processing machine according to the invention and 
           [0069]      FIG. 9  shows a perspective representation similar to  FIG. 7  in the case of the second exemplary embodiment of the processing machine according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0070]    A first exemplary embodiment of a material-working machine, represented in  FIGS. 1 and 2 , comprises a machine frame  10  with two stands  12  and  14 , between which there extends a lower beam  20 , which is preferably fixedly connected to the stands  12  and  14 , and also an upper beam  22 , which is movable in a direction  24  relative to the lower beam  20 , in order to be able to push a flat material part  26  in between the upper beam  22  and the lower beam  20  and also in order to be able to clamp it firmly between the upper beam  22  and the lower beam  20 . 
         [0071]    In this case, the lower beam  20  acts with a lower beam tool  21  and the upper beam  22  acts with an upper beam tool  23  on the flat material part  26 , in order to clamp it in place. 
         [0072]    The flat material part  26  can in this case be positioned and displaced in a supporting plane  30 . 
         [0073]    For bending the flat material part  26  clamped in between the upper beam  22  and the lower beam  20 , a folding beam is provided, designated as a whole by  32 , which is pivotable about a geometrical axis  34  relative to the machine frame  10 , so that a bending tool  36  of the folding beam  32  is capable of bending a protruding leg  40  of the flat material part into a bending space  38 . 
         [0074]    The folding beam  32  is in this case preferably disposed and formed in such a way that bending of the leg  40  is possible in a direction  42  from top to bottom or in a direction  44  from bottom to top. 
         [0075]    For this purpose, a movement of the folding beam is performed for example in a way corresponding to European Patent 0 497 780. As represented in  FIGS. 1 and 2 , the bending space  38  is not freely accessible, but is protected by a housing  46 , which encloses the bending space  38  both in the region of the stands  12  and  14  and by a wall  48  disposed at a distance from the lower beam  20  and the upper beam  22 , and consequently prevents access to the bending space  38  by personnel during the bending of the flat material parts. 
         [0076]    In order to be able to position the flat material  36  exactly for the bending in the supporting plane  30 , a supporting unit is provided, designated as a whole by  50  and having a region  52  toward the tool and a region  54  remote from the tool, which regions are disposed at a distance from one another in a main feed direction  56 , which for its part runs parallel to the supporting plane  30  and transversely, preferably perpendicularly, in relation to the axis  34 . 
         [0077]    In this case, the region  52  toward the tool is preferably fixedly connected to the machine frame  10  and has, for example, a cross member  62 , which is supported in particular on the lower beam  20  and carries supporting strips  64  for the flat material part  26  extending parallel to the main feed direction  56 . 
         [0078]    Furthermore, the region  54  remote from the tool has a cross member  72 , which likewise carries on the one hand supporting strips  74  extending parallel to the main feed direction  56  and on the other hand stop strips  76 . 
         [0079]    According to the concept of the invention, the region  54  of the supporting unit  50  that is remote from the tool, and in particular the cross member  72 , is movable in the main feed direction  56  toward the lower beam  20  or movable away from it, so that an extent A of the supporting unit  50  is variable between a minimum extent A min , represented in  FIG. 2 , and a maximum extent A max , represented in  FIG. 3 , in order always to obtain an optimum extent of the supporting unit  50  for the placement of the flat material part  26  to be processed. 
         [0080]    In particular, this variation of the extent of the supporting unit  50  in the main feed direction  56  can be achieved by the cross member  72  being movable in the main feed direction  56 . 
         [0081]    For this purpose, two longitudinal guides  82  and  84  are provided at a distance from one another in a transverse direction  76  running transversely in relation to the main feed direction  56 , mounted on base frames  86 ,  88  and extending parallel to the main feed direction  56 . 
         [0082]    As represented in  FIGS. 4 and 5 , each of these longitudinal guides  82 ,  84 , in this case the longitudinal guide  82 , comprises a longitudinal guide rail  90 , in which a guide carriage  92  is guided, for example mounted on roller bearings. 
         [0083]    Furthermore, the longitudinal guide rail  90  is seated on a longitudinal member  94 , which also carries a rack  96 , a pinion  98  meshing with the rack  96  and being rotatably disposed on a bearing body  100 , which carries the cross member  72 , which bearing body is for its part also seated on the guide carriage  92  and is guided by the latter along the longitudinal guide rail  90 . 
         [0084]    The bearing body  100  in this case bears a drive shaft  102  of an adjusting drive  110 , which is disposed for example on the cross member on a side remote from the supporting plane  30 . 
         [0085]    The entire cross member  72  is supported on the bearing body  100 , and consequently the region  54  remote from the tool is substantially supported on it in the exemplary embodiments represented. 
         [0086]    The adjusting drive  110  comprises, for example, an electric drive motor  112  and a gear mechanism  114 , and consequently, by driving the pinion  98  via the drive shaft  102 , is capable of displacing the cross member  72 , and consequently the region  54  remote from the tool, relative to the region  52  that is toward the tool, in the main feed direction  56  and positioning them in defined positions between a minimum extent A min  and a maximum extent A max . 
         [0087]    Since—as represented in FIG.  3 —the cross member  72  carrying the region  54  of the supporting unit  50  that is remote from the tool not only carries the supporting strips  74  but also the stop strips  76 , the adjustability of the region  54  remote from the tool, and in particular of the cross member  72 , is at the same time used to position the stop strips  76 , and consequently their stop elements  116  and  118  which can be brought into use, to be precise in dependence on the position of the cross member  72  relative to the tools  21  and  23 . 
         [0088]    For this purpose, the adjusting drive  110  is preferably coupled with a controller  120  for the processing machine, which primarily controls the movement of the lower beam  20  and the upper beam  22  relative to one another and also controls the movement of the folding beam  32  for bending the flat material part  26 . Since the position of the flat material part  26  relative to a bending line defined by the lower beam tool  21  and the upper beam tool  23  is decisive for this, the controller  120  also controls the position of the stop elements  116  and  118  relative to the lower beam tool  21  and the upper beam tool  23 , and consequently ultimately relative to the bending line defined by these tools  21 ,  23 , by controlling the adjusting drive  110  during the bending of the flat material part by the folding beam  32 , the controller  120  selecting and activating those of the stop elements  116 ,  118  that are suitable on the basis of their distance from the bending line. 
         [0089]    Consequently, by virtue of the controller  120  and the resultant positioning of the stop elements  116  or  118 , the extent A of the supporting unit  50  in the main feed direction  56  necessarily varies according to the size of the flat material part  26  to be processed, if it is assumed that the flat material part  26  is to be supported on the stop elements  116  or  118  on its side opposite from the side to be bent, in order to position the side to be bent exactly relative to the lower beam tool  21  and the upper beam tool  23 . 
         [0090]    The variation of the extent A of the supporting unit  50  in the main feed direction  56  between the region  52  toward the tool and the region  54  remote from the tool makes it easily possible for an operator manually to put the flat material parts  26  to be processed in place and lay them against the stop elements  116  or  118 , and consequently position them exactly relative to the tools  21 ,  23  and  36  that are applicable to the processing, an operator having the possibility of always being able to take hold of and displace the flat material part  26  on its region intended for butting against one of the stop elements  116  or  118 . 
         [0091]    Consequently, the flat material part  26  always remains ergonomically favorably within reach of the person standing in front of the region  54  remote from the tool, in particular near the cross member  72 , for the handling on the supporting unit  50 . 
         [0092]    To provide additional support for the flat material part  26  between the region  52  toward the tool and the region  54  remote from the tool, an intermediate cross member  122  is provided between the cross member  62  and the cross member  72  and for its part carries supporting strips  124 . 
         [0093]    In this case, the intermediate cross member  122  is always positioned between the cross member  62  and the cross member  72 , preferably approximately midway between the two, irrespective of the distance between the cross member  72  and the cross member  62 , by a pantograph drive mechanism  130 . 
         [0094]    As represented in  FIG. 4 , the pantograph drive mechanism  130  in this case comprises a pantograph lever  132 , which is articulatingly connected to the cross member  62  and is also articulatingly connected to a carriage  134 , which is guided in the longitudinal direction of the intermediate cross member  122 , sliding on the latter. 
         [0095]    Also articulatingly mounted on the carriage  134  is a pantograph lever  136 , which for its part is articulatingly connected to the cross member  72 . 
         [0096]    The two pantograph levers  132  and  136  consequently have the effect that the carriage  134 , guided in a sliding manner along the intermediate cross member  122 , is always positioned in an intermediate position relative to the cross member  62  and the cross member  72 , preferably approximately midway between them, the intermediate cross member  122  lying virtually against the cross member  62  and the cross member  72  being disposed at a small distance from the intermediate cross member  122  in the case of the minimal extent of the supporting unit  50 , represented in  FIG. 7 , whereas in the case of the maximum extent of the supporting unit  50 , represented in  FIG. 4 , the cross member  72  is at the maximum distance from the cross member  62  and the intermediate cross member  122  is approximately midway between them, and is kept in this position by the pantograph drive mechanism  130 . 
         [0097]    In all the intermediate positions between the state of maximum extent of the supporting unit  50  and minimum extent of the supporting unit  50 , the pantograph drive mechanism  130  always keeps the intermediate cross member  122  substantially midway between the cross member  72  and the cross member  62 . 
         [0098]    Preferably, the intermediate cross member  122  is also guided in a sliding manner on the longitudinal guide rail  90  by a corresponding guide carriage  92 , so that no additional guidance is required for the movement of the intermediate cross member  122  in the main feed direction  56 . 
         [0099]    Preferably, as represented in  FIGS. 1 and 2 , the supporting strips  64 ,  74  and  124  are disposed on the cross members  62 ,  72  and  122  in such a way that, in the state of minimum extent of the supporting unit  50  represented in  FIGS. 2 and 7 , the supporting strips  64 ,  74  and  134  lie next to one another and do not protrude beyond either the cross member  62  or the cross member  72 , whereas in intermediate positions between the state of minimum extent of the supporting unit  50  in the main feed direction  56  and the state of maximum extent of the supporting unit  50  in the main feed direction  56 , portions of the supporting strips  64 ,  74  and  124  lie next to one another, as represented in  FIG. 1 , so that, as before, adequate support on the supporting unit  50  of the flat material part  26  to be processed can be achieved. 
         [0100]    As represented in  FIGS. 1 and 2 , the supporting unit  50 , which is variably adjustable with respect to its extent in the main feed direction  56 , does not extend over the entire extent of the processing tools  21 ,  23  and  36  in the transverse direction  78 , but rather only over a partial region of the same. 
         [0101]    The supporting unit  50 , variable in the main feed direction  56 , is preferably further supplemented by supporting tables  142  and  144 , which adjoin it on both sides in the transverse direction  78  and carry supporting strips  146  extending over their entire extent in the main feed direction  56 . 
         [0102]    However, the cross member  72  also extends under the supporting strips  146  of the supporting tables  142  and  144  in order to displace in the main feed direction  56  stop strips  76  disposed between these supporting strips  146 , so that the stop strips  76  can together be positioned over the entire extent of the supporting unit  50 , and also of the supporting tables  142  and  144  laterally adjoining them in the transverse direction  78 , by moving the cross member  72  in the main feed direction  56 . 
         [0103]    The supporting tables  142  and  144  are preferably formed in such a way that the longitudinal guides  82  and  84  are integrated into them and that the supporting tables  142  and  144  are also respectively carried by the base frames  86  and  88 . 
         [0104]    To operate the controller  120 , an operator unit  126  is disposed on a side of the machine frame  10  that is toward the supporting unit  50 —as represented in FIG.  2 —and said unit is still within reach of the operator standing in front of the end region  54  remote from the tool, in order to call up the required control programs. 
         [0105]    Furthermore, also disposed at the end region  54  remote from the tool is an operating element  128 , which can be moved along with the end region  54  and can consequently be actuated in an ergonomically favorable manner, for example for initiating each and every bending operation. 
         [0106]    In the case of a second exemplary embodiment of a material-working machine according to the invention, the supporting unit  50 ′ is disposed on the base frames  86  and  88 , as represented in  FIGS. 8 and 9 , the base frames  86  and  88  respectively carrying a longitudinal guide  82  and  84 , which is formed in the same way as in the case of the first exemplary embodiment. 
         [0107]    On this longitudinal guide  82  and  84 , the cross member  72  is then once again guided by means of guide carriages  92 , which are disposed on the bearing body  100 . 
         [0108]    In the same way as in the case of the first exemplary embodiment, the cross member  72  is movable, but it does not carry any supporting strips  74 , but merely stop elements  118 , which protrude upward beyond the supporting surface  152  of the cross member  72 . 
         [0109]    Furthermore, in the case of the second exemplary embodiment of the supporting unit  50 ′, the supporting plane  30  is formed in addition to the supporting surface  152  by supporting rollers  154 , which are disposed such that they follow one another in the main feed direction  56  and are guided in a supporting roller guide  156 , the supporting roller guide  156  having a portion  162  running parallel to the main feed direction  56  and a portion  164  running near the lower beam  20 , transversely with respect to the portion  162 , in which portion  164  the supporting rolls  154  that are not in the portion  162  can be positioned. 
         [0110]    The supporting rollers  154  that are respectively in the portion  162  of the supporting roller guide  156  contribute here to supporting the flat material part  26  to be processed in the supporting plane  30 , while the other supporting rollers  154  can be stored in the portion  164 . 
         [0111]    The supporting rollers  154  are in this case connected to one another and to the cross member  72 ′, for example by tie elements, so that a displacement of the cross member  72 ′ away from the processing tools  21 ,  23 ,  36  has the effect that the supporting rollers  154  are successively drawn up out of the portion  164  into the portion  162  of the supporting roller guide  156  and, by providing guidance in the portion  162 , contribute to the supporting plane  30  between the lower beam  20  and the cross member  72 ′, as represented for example in  FIG. 8 . 
         [0112]    In the state of maximum extent of the supporting unit  50 ′ in the main feed direction  56 , all the supporting rollers  154  are located in the portion  162 . 
         [0113]    If, on the other hand, the extent of the supporting unit  50 ′ in the main feed direction  56  is to be minimized, the cross member  72 ′ is moved in the direction of the processing tools  21 ,  23 ,  36  and, as a result, the supporting rollers  154  are transferred one after the other from the portion  162  into the portion  164  of the supporting roller guide  156 , the supporting rollers  154  being stored in the portion  164 . 
         [0114]    Consequently, the supporting roller  154  that is closest to the lower beam  20  while still in the portion  162  forms the region  52  of the supporting unit  50 ′ that is toward the tool, while the cross member  72 ′ with the supporting surface  152  forms the region  54  of the supporting unit  50  that is remote from the tool.