Patent Publication Number: US-6658913-B1

Title: Multistage metal-forming machine tool having tool combination blocks

Description:
FIELD OF THE INVENTION 
     The present invention relates to a multi-stage forming machine with combined tool blocks. 
     BACKGROUND OF THE INVENTION 
     In conventional multi-stage forming machines, the removal, fastening and setting of tools requires the loosening or screwing in of screws, so that a tool change normally takes around an hour or more. Since the forming machine is out of operation during this time, this entails a considerable loss in productivity. Therefore, forming machines which allow a faster tool change have been developed. 
     DE-A-197 22 228 discloses a multi-stage forming machine in which each tool is arranged in a tool cartridge which is held in the forming machine by means of a clamping device. The securely clamped tool cartridges can be exchanged relatively quickly as and when required, so that the downtime of the forming machine can be reduced considerably. However, a tool change still takes a comparatively long time, since the fine setting of the distance between two opposite interacting tools is performed on the forming machine. 
     EP-B-0 354 428 describes a multi-stage forming machine which comprises a first combined tool block, with for example five female-die blocks, fitted on a fixed machine body, and a second combined tool block, with for example five male-die blocks, fitted on a press slide which can be moved back and forth in the direction of the said first combined tool block. The combined tool blocks are exchangeable as a whole and can be set outside the forming machine. To obtain adequate clamping, the combined tool blocks are screwed to the machine body or press slide. This has the disadvantage that quick changing of combined tool blocks is not possible, since the operating personnel have to work from the outside using auxiliary tools. 
     In view of the disadvantages of the previously known forming machines described above, the invention is based on the following object. It is intended to provide a multi-stage forming machine of the type mentioned at the beginning in which the downtime of the forming machine when changing tools can be reduced considerably with respect to comparable forming machines of the prior art. 
     SUMMARY OF THE INVENTION 
     The essence of the invention is that a multi-stage forming machine comprises a first and second combined tool block, of which at least one has at least one clamping lug, by which it is suspended, by means of a clamping cam fitted directly or indirectly on a fixed machine body or on a press slide, directly or indirectly from above on the machine body or on the press slide. The clamping lug and the clamping cam are designed in such a way that the dead weight of the combined tool block and/or a clamping force acting in the vertical direction on the combined tool block produces a resilient clamping together of the combined tool block and the machine body or press slide in the horizontal direction. The first and second combined tool blocks have interacting individual tool blocks and are respectively fitted on the fixed machine body and the press slide, which can be moved back and forth in the direction of the first combined tool block. 
     The suspending of the combined tool block by clamping lugs directly or indirectly on the machine body or on the press slide makes it possible for the combined tool block to be fitted and removed quickly, since it is possible to dispense with screwing. The necessary clamping of the combined tool block to the machine body or press slide is produced by the clamping lug and the clamping cam, which partially deflect the dead weight of the combined tool block and/or a clamping force acting in the vertical direction on the combined tool block into a horizontal clamping force. The clamping has the effect of prestressing the clamping lug in such a way that it is additionally loaded only insignificantly by production-related forces on the combined tool block, as a result of which it is fatigue-resistant. Any clamping device can be arranged outside the tool space, so that it does not take up any space in the latter. The exchanging of an entire combined tool block allows the fine setting of the distance between two opposite interacting individual tool blocks outside the forming machine, while the latter can continue to be operated with the old combined tool block. The downtime can in this way be restricted to the removal of the old combined tool block and the actual fitting of the new combined tool block. 
     Normally, both combined tool blocks are provided with at least one clamping lug and are suspended directly or indirectly on the machine body or press slide, but it is also conceivable in principle for one of the combined tool blocks to be fastened in some other way. 
     In a first advantageous design variant, the said at least one clamping lug is arranged in the upper edge region of the combined tool block and at least one further clamping lug is arranged in the lower edge region of the combined tool block and is suspended by means of a further clamping cam from above directly or indirectly on the machine body or on the press slide. 
     In a second advantageous design variant, the said at least one clamping lug is arranged in the upper edge region of the combined tool block and at least one downwardly projecting clamping cam is arranged in the lower edge region of the combined tool block and is pushed into an upwardly open clamping lug fitted directly or indirectly on the machine body or on the press slide. 
     These two design variants make it possible for the combined tool block to be clamped uniformly at the top and bottom. 
     The clamping lug or lugs and/or the clamping cam or cams advantageously has or have a bearing face for the assigned clamping cam or clamping lug, which face is inclined with respect to the vertical and is preferably curved, so that when a vertically downwardly directed force is exerted on the combined tool block the clamping lug or lugs is or are bent outwards by the assigned clamping cam or cams. The resilient bending of the clamping lug or lugs allows a high prestressing to be produced in the horizontal direction, which provides a secure, clamped fastening of the combined tool block, counteracts the development of fretting corrosion and makes it unnecessary for the contact surfaces to fit one another absolutely exactly. The curving of the bearing face prevents edge pressure from occurring. 
     A plurality of clamping lugs are advantageously arranged in the upper edge region of at least one of the two combined tool blocks and/or a plurality of downwardly projecting clamping cams are advantageously arranged at intervals next to one another in the lower edge region of this combined tool block. As a result, the combined tool block can be supported and clamped over a wide area. 
     The combined tool block with clamping lugs or at least one of the combined tool blocks with clamping lugs advantageously has at least one stop which rests from above on a stopping face outside the combined tool block. The combined tool block is thus accurately positioned vertically during suspension and thereby defines the maximum clamping force. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The multi-stage forming machine according to the invention is described in more detail below on the basis of an exemplary embodiment with reference to the attached drawings, in which: 
     FIG. 1 shows part of a multi-stage forming machine according to the invention with a combined tool block and releasing device on the female die side, in a vertical sectional view; 
     FIGS. 2 and 3 show detailed sectional views of a clamping lug, stop and clamping cam of the forming machine during suspension; 
     FIG. 4 shows part of the forming machine with a combined tool block and clamping device on the female die side, in a further vertical sectional view; 
     FIG. 5 shows the part of the forming machine on the female die side with the combined tool block removed, seen from the male die side; 
     FIG. 6 shows the removed combined tool block on the female die side of the forming machine; 
     FIG. 7 shows part of the forming machine with a combined tool block and releasing device on the male die side, in a vertical sectional view; 
     FIG. 8 shows part of the forming machine with a combined tool block and clamping device on the male die side, in a further vertical sectional view; 
     FIG. 9 shows the part of the forming machine on the male die side, with the combined tool block removed, seen from the female die side; and 
     FIG. 10 shows the removed combined tool block on the male die side of the forming machine. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 to  6 —part of the forming machine on the female die side 
     A multi-stage forming machine according to the invention comprises a machine body  1 , to which an apron  5  is fastened by means of screws  15 . Force-absorbing wedges  16  (FIG.  4 ), arranged in wedge-shaped recesses  53  (FIG. 5) in the apron  5  serve in addition to the screws  15  for supporting the vertical clamping forces occurring. Running through the machine body  1  and the apron  5  are an ejector-rod bore  28  and an ejector-rod guide  29  (FIG.  4 ). At its upper end, the apron  5  has two elongated clamping cams  52 , which extend on either side of a centring housing  12 , arranged above the apron  5 , respectively up to the lateral edge of the said apron. At the lower end of the apron  5 , four upwardly projecting clamping lugs  51  are fitted, distributed over its width. 
     Suspended in the apron  5  is a combined tool block  3 , with a supporting plate  32 , a centring plate  36 , normally five female-die blocks  35  and a block guide  34  extending over the entire width. Drawn in FIG. 6 is a female-die block  35 , which is fastened to the centring plate  36  by means of screws  24 . The clamping of the female die takes place by means of claws  351  and claw screws  352 . The block guide  34 , centring plate  36  and supporting plate  32  are connected to one another by means of screws  18  and the centring plate  36  and supporting plate  32  are additionally connected to each other by means of screws  17 . Four clamping lugs  31  are formed at the upper end of the supporting plate  32 , evenly distributed over the width, while four clamping cams  322  are formed at the lower end. Fastened by means of screws  19  to the supporting plate  32  respectively between the two outer clamping lugs  31  are stops  33 , which rest on stopping faces  521  on the clamping cams  52  of the apron  5  and thus accurately position the combined tool block  3  vertically. Force-absorbing wedges  316  (FIGS.  2  and  3 ), arranged in wedge-shaped recesses  323  (FIG. 6) in the supporting plate  32 , serve in addition to the screws  19  for supporting the clamping forces occurring. The supporting plate  32  has, furthermore, slot-shaped recesses  324 , which make it possible for the combined tool block  3  to be inserted and lifted out, whilst ejector rods protrude into the region of the supporting plate  32 . 
     For the horizontal centring of the combined tool block  3 , a centring pin  11  with a spherical head is screwed into the supporting plate  32  (FIG.  4 ). During the suspension of the combined tool block  3 , the spherical head is inserted into the centring housing  12  and directed into the desired horizontal position by the special design of the said housing (FIG.  5 ). 
     The suspension of the combined tool block  3  in the apron  5  generally takes place by means of an external crane device (not shown here) To make it easier for the combined tool block  3  to be fitted into the tool space, insertion aids  21 ,  22  are provided on the machine body  1  and on the apron  5 . The clamping lugs  31  of the combined tool block  3  are hung over the clamping cams  52  of the apron  5 , while the clamping cams  322  of the combined tool block  3  are inserted between the clamping lugs  51  and the vertical bearing face of the apron  5  and the spherical head of the centring pin  11  is inserted into the centring housing  12 . Thus, the dead weight of the combined tool block  3  is used to achieve a position in which the stops  33  are not yet resting on the stopping faces  521  of the clamping cams  52 , but the clamping lugs  31  have already been minimally bent resiliently outwards by the clamping cams  52  in the direction of the arrow A (FIG.  3 ). In a corresponding way, the clamping lugs  51  have also been minimally bent resiliently outwards by the clamping cams  322 . The clamping lugs  31  and  51  are in this way prestressed and exert a horizontal clamping force, which clamps together the combined tool block  3  and the apron  5 , and consequently indirectly the machine body  1 . 
     Since the clamping brought about by the dead weight of the combined tool block  3  is generally not adequate, a clamping force acting in the vertical direction on the combined tool block  3  is produced by two clamping devices  7  arranged underneath the combined tool block  3  (FIGS. 4,  5 ), by means of which force the clamping lugs  31  and  51  are further bent resiliently outwards and the clamping is increased to the desired degree. The clamping devices  7  each comprise a clamping lever  71 , which can be pivoted about a clamping lever spindle  73  mounted on the apron  5 . The clamping levers  71  can be actuated by means of hydraulic cylinders  74  with rams  741  and, when actuated, press down clamping clips  72  fastened by means of screws  20  to the supporting plate  32 . The two extreme positions of a clamping lever  71  are drawn in FIG.  4 . Bending springs  75  ensure that the clamping levers  71  are constantly in contact with the rams  741  of the double-acting hydraulic cylinders  74 . 
     The clamping forces and clamping arrangements required vary according to the size of machine. With two clamping devices  7 , material-dependent deformations of the clamping lugs  31 ,  51  in the range of tenths of a millimetre and a clamping force in the pressing direction of 250 kN were achieved with a vertical clamping force on the two clamping clips  72  of 110 kN in each case. In the case of smaller or larger forming machines, the clamping devices  7  were designed for clamping forces in the pressing direction of 125 kN and 500 kN, respectively. 
     For releasing the combined tool block  3 , a releasing device  9  arranged thereunder is provided, the said device comprising a release lever  91 , which can be pivoted about a release-lever spindle  92  and is mounted on a carriage  93  fastened to the machine body  1 . The release lever  91  can be actuated by means of a hydraulic cylinder  94  with ram  941  and, when actuated, presses up a lifting element  95 , fastened to the centring plate  36  by means of screws  23 . The two extreme positions of the release lever  91  are drawn in FIG.  1 . 
     FIGS. 7 to  10 —part of the forming machine on the male die side 
     The fastening of a combined tool block  4  on the male die side to a press slide  2 , which can be moved back and forth in the direction of the combined tool block  3  on the female die side, takes place in principle in the same way as the fastening of the combined tool block  3  on the female die side to the machine body  1 . 
     An apron  6  is fastened to the press slide  2  by means of screws  115 . At its upper end, the apron  6  has six elongated clamping cams  62 , distributed over its width, while four upwardly projecting clamping lugs  61  are fitted at its lower end. The apron  6  has, furthermore, slot-shaped recesses  64 , which make it possible for the combined tool block  4  to be inserted and lifted out, whilst ejector rods on the tool side protrude into the region of the apron  6 . 
     The combined tool block  4  is suspended in the apron  6  with a wedge-shaped supporting plate  42 , five adjusting wedges  44 , an adjusting-wedge housing  47  and normally five adjusting plates  46  and five male-die blocks  45 . In FIG. 10 there is drawn only one male-die block  45 , fastened to the associated adjusting plate  46  by means of screws  124 . The clamping of the male dies takes place by means of claws  451  and claw screws  452 . The adjusting plates  46  are fastened to the adjusting-wedge housing  47  by means of bolts  126  and nuts  127  screwed into the adjusting-wedge housing  47 , the adjusting plates  46  having play around the bolts  126  before the nuts  127  are securely screwed, so that the said adjusting plates can be aligned with the female dies. The supporting plate  42  and the adjusting-wedge housing  47  are connected by means of screws  117 . 
     Four clamping lugs  41  are formed at the upper end of the supporting plate  42 , distributed over the width, while four clamping cams  422  are formed at the lower end, on either side of a centring housing  14  arranged underneath the supporting plate  42 . Fastened by means of screws  25  to the supporting plate  42  respectively between the two outer clamping lugs  41  are stops  43 , which rest on stopping faces  621  on the clamping cams  62  of the apron  6  and thus accurately position the combined tool block  4  vertically. Force-absorbing wedges  416 , arranged in wedge-shaped recesses  423  (FIG. 10) in the supporting plate  42 , serve in addition to the screws  25  for supporting the clamping forces occurring. 
     For the horizontal centring of the combined tool block  4 , a centring pin  13  with a spherical head is screwed into the apron  6  (FIG.  7 ). During the suspension of the combined tool block  4 , the centring housing  14  is guided by means of the spherical head and directed into the desired horizontal position. 
     The suspension of the combined tool block  4  in the apron  6  takes place again by means of an external crane device (not shown here). The clamping lugs  41  of the combined tool block  4  are hung over the clamping cams  62  of the apron  6 , while the clamping cams  422  of the combined tool block  4  are inserted between the clamping lugs  61  and the vertical bearing face of the apron  6  and the centring housing  14  is guided by means of the spherical head of the centring pin  13 . Thus, the dead weight of the combined tool block  4  is used to achieve a position in which the stops  43  are not yet resting on the stopping faces  621  of the clamping cams  62 , but the clamping lugs  41  and/or  61  have aready been minimally bent resiliently outwards by the clamping cams  62  and  422 , respectively. The clamping lugs  41  and  61  are in this way prestressed and exert a horizontal clamping force, which clamps together the combined tool block  4  and the apron  6 , and consequently indirectly the press slide  2 . 
     Since the clamping brought about by the dead weight of the combined tool block  4  is generally not adequate, a clamping force acting in the vertical direction on the combined tool block  4  is produced by two clamping devices  8  arranged underneath the combined tool block  4  (FIGS. 8,  9 ), by means of which force the clamping lugs  41  and  61  are further bent resiliently outwards and the clamping is increased to the desired degree. The clamping devices  8  each comprise a clamping lever  81 , which can be pivoted about a clamping lever spindle  83  mounted on the apron  6 . The clamping levers  81  can be actuated by means of hydraulic cylinders  84  with rams  841  and, when actuated, press down clamping clips  82  fastened by means of screws  120  to the supporting plate  42 . The two extreme positions of a clamping lever  81  are drawn in FIG.  8 . Bending springs  85  ensure that the clamping levers  81  are constantly in contact with the rams  841  of the double-acting hydraulic cylinders  84 . 
     The clamping forces and clamping arrangements correspond approximately to those for the combined tool block  3  on the female die side. 
     For releasing the combined tool block  4 , a releasing device  10  arranged thereunder is provided, the said device comprising a release lever  101 , which can be pivoted about a release-lever spindle  102  and is mounted on the apron  6 . The release lever  101  can be actuated by means of a hydraulic cylinder  104  with ram  106  and, when actuated, presses up the combined tool block  4  by means of the centring housing  14  arranged on the supporting plate  42 . The two extreme positions of the release lever  101  are drawn in FIG.  7 . 
     Further design variations of the parts described above of a forming machine can be realized. It should also be expressly mentioned here that there are many conceivable alternatives for the clamping and releasing mechanisms, such as toggle-lever, screw, cone or wedge clamping systems.