Abstract:
A device and a method for shaping sheared edges on stamped or fine-blanked parts having a burr include at least one cutting stage and at least one forming stage. The forming stage includes a shaping punch which has a shaping region for smoothing the sheared edge of the outer or inner contour of the workpiece to the net shape and an embossing shoulder for mashing the burr of the outer or inner contour. The shaping punch is configured so that the shaping region initially bends the burr on the outer or inner contour away from the sheared edge, then seizes the sheared edge for widening, wherein the embossing shoulder of the shaping punch mashes the burr on the outer or inner contour when the widening on the workpiece has ended and flattens the embossing bead, created during mashing, during separating of the shaping punch from the workpiece.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a device for shaping sheared edges on stamped or fine-blanked workpieces such as bobs, disks, synchronizer rings for clutches or the like, having a burr, comprising an upper part and a lower part, which form at least one cutting stage for cutting the outer and/or inner contours of the workpiece, and at least one forming stage for mashing the burrs created during cutting, wherein the forming stage is divided into a fixed upper die part having an embossing be and a lower the part movable in the stroke direction having an embossing anvil. 
     The invention further relates to a method for shaping sheared edges of stamped or fine blanked-workpieces such as bobs, disks, synchronizer rings or the like, having a burr, in which the outer contour and/or inner contour of a workpiece are cut from a flat strip within a device comprising an upper part and a lower part in a stamping or fine blanking stage, the cut workpiece is transferred into a forming stage by a cross slide ( 16 ) after the device has been opened, and the net shape of the workpiece is created in this forming stage. 
     Stamped and fine-blanked parts are known to have a burr on the side of the sheared edge opposite the punch side, the size of the burr being dependent on various influencing factors, such as the die clearance between the punch and the die plate, the strength of the material, and the wear of the punch and cutting plate (see DIN 6930 and VDI Guideline 2906). This burr is undesirable since it limits the functional capability of high-precision parts. The burr must be removed by way of reworking, which necessitates additional complex work steps, such as grinding and brushing, for example, recutting (CH 665 367 A5) or mashing the burr edges (DE 41 13 165 A1, U.S. Pat. No. 3,478,558 A, DE 10 2004 020 483 A1, DE 10 2006 018 847 34). 
     The sheared edges of stamped parts additionally exhibit a variably large fracture surface, which considerably reduces the functional area, which is to say the flush-cut surface, so that in addition to removing the burr, it is also necessary to rework the entire sheared edge, losing material, so as to ensure a final contour of the part that is true to shape. 
     In particular in the case of parts having non-circular inner contours, such as kidney-shaped or elliptic openings, apertures or holes in the workpiece, reworking is particularly complex, since the subsequent mashing of the burr edges by way of roller bodies (DE 41 13 165, DE 10 2004 020 483 A1) is not suitable here, and only grinding and brushing of the cut edges will ensure the necessary precision. 
     Subsequent mashing of the burr has the added disadvantage that an embossing bead is formed, which detracts from the accuracy of the sheared edge. 
     SUMMARY OF THE INVENTION 
     With this prior art in mind, it is the object of the invention to create a device and a method for shaping sheared edges on stamped or fine-blanked parts such as bobs, disks, synchronizer rings or the like, having a burr, which make it possible to achieve a high-precision inner contour and outer contour on stamped or fine-blanked parts in a way that is true to shape and dimensions, while also eliminating reworking and saving material and costs. 
     The core idea of the solution according to the invention is to first bring the entire sheared edge of an outer contour or inner contour on a stamped or fine-blanked part, such as of an elliptic hole, having a burr into such a position that the burr can be bent away from the cut edge on the workpiece, then widen the sheared edges on the inner contour in a defined manner to the net shape and dimensions using a shaping punch, and subsequently completely flatten the embossing bead created during mashing, within one stage. 
     This is achieved in that the forming stage comprises a shaping punch, which has a shaping region for smoothing the sheared edge of the outer or inner contour to the net shape and an embossing shoulder for mashing the burr of the outer or inner contour, the embossing shoulder being designed so that the shaping region initially bends the burr on the outer or inner contour away from the sheared edge, then seizes the sheared edge for widening, wherein the embossing shoulder of the shaping punch mashes the burr on the outer or inner contour when the widening on the workpiece has ended, forming an embossing bead, and flattens the embossing bead during demolding of the shaping punch. 
     It is particularly advantageous that the shaping punch has shapes and dimensions that are adapted to the outer contour or inner contour of the workpiece, for example circular or non-circular openings, such as holes, boreholes, or cut-outs. This makes it possible to use the device according to the invention for the production of stamped or fine-blanked parts having different configurations, such as bobs, disks, synchronizer rings, or the like. 
     According to a preferred embodiment variant of the device according to the invention, the shaping region of the shaping punch is formed of a spherical segment-shaped thickening that is provided at the head end of the punch and is oversized in a defined manner in relation to the outer or inner contour so as to radially widen the sheared edge and flatten the embossing bead. During the stroke movement of the workpiece, the thickening of the shaping region engages the sheared edge and displaces the material radially into the workplace, so that an evenly smooth surface is imparted to the sheared edge of the inner contour, which can be brought into the desired net shape and dimensions. During demolding of the shaping punch, which is to say during the return movement of the shaping punch counter to the stroke direction, the shaping region moves past the embossing bead, flattening the same. 
     In a further embodiment of the device according to the invention, the shape and dimensions of the shaping punch are adapted to the inner contour of the workpiece, for example circular or non-circular openings such as holes, boreholes or cut-outs. This makes it possible to use the device according to the invention for the production of stamped or fine-blanked parts having different configurations, such as bobs, disks, synchronizer rings, or the like. 
     In a refinement of the invention, the embossing shoulder is provided on the shaping punch at a height on the head end of the shaping punch at which, during the vertical movement of the workplace, the shaping region of the shaping punch first slightly bends the burr present on the outer or inner contour away from the sheared edge, then seizes the sheared edge of the outer or inner contour for widening, and flattens the embossing bead during the return stroke of the shaping punch. 
     In a further embodiment of the device according to the invention, the shaping punch is fixed on an upper block of the upper part in a stationary manner. 
     In a further advantageous embodiment of the device according to the invention, the embossing bell is provided with an embossing shoulder, wherein an ejector that is designed to be movable in the stroke direction is provided in the embossing bell for vertically guiding the shaping punch. 
     So as to fix the outer contour of the workplace, the embossing bell has an annular design and completely surrounds the outer contour of the workplace. 
     The spring-loaded holder for the embossing anvil is vertically guided in an embossing positioning plate held by a cavity frame and has a support surface, which forms a seat for the embossing bell when the upper die part and the lower die part are closed. 
     The cavity frame is fixed on the lower block in the stationary manner, in which the lower additional hydraulic unit is accommodated, which via a lower embossing pressure plate that is additionally supported by a spring force is operatively connected to the embossing anvil by lower pressure pins. 
     A further preferred embodiment of the device according to the invention provides for the upper additional hydraulic unit accommodated in an upper block to be operatively connected to the ejector via an upper embossing pressure plate, and for the shaping punch to be attached in a fixed position on the upper embossing pressure plate, wherein the ejector is operatively connected to the upper additional hydraulic unit via pressure pins that are subject to additional spring force for detaching the finished workpiece. 
     The object is further achieved by a method in which the following steps are carried out in a single operation in the forming stage:
         a) slightly bending the burr present on the sheared edge of the outer or inner contour away from the sheared edge by way of a shaping punch having a shaping region, when the workpiece carries out a vertical movement in the stroke direction;   b) widening the sheared edge of the outer or inner contour of the workpiece, by way of the shaping region of the shaping punch, to the desired net shape and dimensions until the embossing shoulder on the shaping punch seizes the burr on the sheared edge of the outer or inner contour;   c) creating an embossing bead in the sheared edge by mashing the burr of the outer or inner contour on the workpiece by way of the embossing shoulder of the shaping punch;   d) flattening the embossing bead by way of the shaping region of the shaping punch during demolding thereof from the workpiece, by way of a vertical movement of the shaping punch counter to the stroke direction of the workpiece.       

     It is particularly advantageous for the widening of the sheared edge to the desired net shape and dimensions to begin on the side of the sheared edge facing the burr and to end on the burr-less sheared edge, without the orientation of the slightly bent burr changing during the widening step. 
     In a further embodiment of the method according to the invention, shaping punches having different shapes and dimensions may be used. The only prerequisite is that the shaping punch is adapted to the inner contour of the workpiece, for example to circular or non-circular openings, such as holes, boreholes or cut-outs, with a defined oversized dimension. This makes it possible to use the method according to the invention for stamped or fine-blanked parts having different configurations, such as centrifugal weights, disks, synchronizer ring, or the like. 
     A further advantageous embodiment of the method according to the invention provides for the burr of the outer contour to be mashed, simultaneously with the burr of the inner contour, by an embossing shoulder of the embossing bell, wherein the outer contour of the workpiece is fixed by the embossing be forming part of the upper the part, and the workpiece is deposited on the embossing anvil of the lower the part in an appropriately positioned manner. 
     Further advantages, features and details of the invention will be apparent from the following description with reference to the accompanying drawings. 
     The invention shall be described in more detail hereafter based on the example of producing a bob having elliptic holes as the inner contour. It goes without saying that the invention also covers stamped or fine-blanked parts having different shapes at the outer and inner contours, such as disks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIGS. 1 a  and 1 b    show a perspective view and a section along line A-A of  FIG. 1 a    of a fine-blanked workpiece for a commercially available centrifugal weight; 
         FIG. 2  shows a perspective top view onto an exemplary arrangement of a fine blanking stage and a forming stage in a device according to the invention; 
         FIG. 3 a    shows a schematic sectional illustration of the forming stage in the open state; 
         FIG. 3 b    shows a schematic sectional illustration of the forming stage with a returned embossing anvil; 
         FIG. 3 c    shows a schematic sectional illustration of the forming stage in the clamped state; 
         FIG. 3 d    shows a schematic sectional illustration of the forming stage in the state after mashing of the burr; 
         FIG. 3 e    shows a schematic sectional illustration of the forming stage with a workplace partially detached from the shaping punch; 
         FIG. 3 f    shows a schematic sectional illustration of the forming stage during opening; 
         FIG. 4  shows an enlarged illustration of the shaping punch comprising an embossing shoulder and a shaping region provided at the head; 
         FIG. 5  shows a perspective view of the upper die part of the device according to the invention in a depiction of revolution; 
         FIG. 6  shows an enlarged illustration of the embossing bell comprising the embossing shoulder; 
         FIG. 7  shows a perspective view of the lower die part; 
         FIG. 8  shows a perspective view of the embossing anvil with the holder; and 
         FIGS. 9 a  to 9 e    show schematic illustrations of the sequence of the method according to the invention with simultaneous mashing of the burrs on the outer and inner contours. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 a  and 1 b    show a workplace  1  for a bob, for example, which was produced by way of fine blanking. On the outer contour  2 , it has sheared edges  3  having rollover  4  and a burr  5 , wherein the burr  5  is located on the side  6  of the workplace  1  facing away from the rollover. The inner contour  7  is formed by the sheared edges  8 , which are part of two ellipsoidal holes  9 . The sheared edges  8  likewise have a corresponding burr  5 . 1 . The workpiece  1  has a thickness D of 6 mm, for example, and is made of steel. 
     The workplace  1  is to be produced in a device that comprises an upper part  10  and a lower part  11  and—as shown in  FIG. 2 —is composed of at least one fine blanking stage  12  and at least one forming stage  13 . 
     The upper block  14  ( FIG. 3 a   ) of the upper part  10  is fixed in a stationary manner on a machine table, which is not shown, and the lower block  15  of the lower part  11  is fixed on a ram of a press so as to be able to perform stroke movements, so that the workpiece  1  is fine-blanked from bottom to top—which is to say in the direction of the upper part—from a flat strip in the fine blanking stage  12 , which corresponds to the known prior art and therefore need not be described in more detail. 
     The burr  5  of the sheared edge  3  of the outer contour  2  projects perpendicularly downward, while the burr  5 . 1  of the sheared edge  8  of the inner contour  7  projects perpendicularly upward from the workplace  1  (see also  FIG. 1 b   ). 
     After having been ejected from the fine blanking stage  12 , the fine-blanked workpiece  1  is seized by a cross elide  16  and transported by the same into the forming stage  13 , where the workpiece is deposited in an accurately positioned manner prior to the forming step (see also  FIGS. 3 a  to 3 f   ). 
       FIGS. 3 a  to 3 f    show the basic design of the forming stage  13  in a variety of processing states. The forming stage  13  comprises an upper die part  17  and a lower die part  18 . 
     The upper die part  17  includes an annular embossing bell  19 , an ejector  20 , and shaping punch  21 . The embossing bell  19  is fixed to an upper embossing block  22   a  in a stationary manner, the embossing block  22   a  in turn being fixed to the upper block  14 . 
     The ejector  20  is supported vertically on the inner wall of the embossing bell  19  and horizontally on the upper embossing pressure plate  22 , such that the ejector  20  is able to carry out a vertical relative movement with respect to the embossing bell  19 . 
     The operative connection between the ejector  20  and the upper embossing pressure plate  22  is established by pressure pins  25  that are additionally subject to spring force. 
     The shaping punch  21  is inserted into the ejector  20 , the punch in turn being held on the upper embossing block  22   a  in a stationary manner. 
     The embossing pressure plate  22  is accommodated in the upper embossing block  22   a  and is operatively connected to an upper additional hydraulic unit  23  and a pressure pin  24 . The ejector  20  is vertically guided and supported on the outer wall of the embossing bell  19  on one side and on the shaping punch  21  on the other side. 
     The lower die part  18  is formed by a cavity frame  26 , a holder  27 , and an embossing anvil  8 . The cavity frame  26  is attached to the lower block  15 . The embossing anvil  28  is seated on a lower embossing pressure plate  29 , which in turn is operatively connected via a lower additional hydraulic unit  30 . The operative connection between the embossing pressure plate  29  and the lower additional hydraulic unit  30  is ensured by lower pressure pins  32 . In addition, the lower embossing pressure plate  29  is held with the lower black  15  via a pin  38  that is placed under spring action by a compression spring  44 . 
     The holder  27 , which contains the embossing anvil  28 , is held in a spring-loaded manner on an intermediate plate  42  by way of a compression spring  31  guided by a pin  43 , so that the holder  27  is able to carry out a vertically directed relative movement with respect to the embossing anvil  28  and the embossing positioning plate  29 . 
     The holder  27  moreover has a support surface  46 , which forms a seat for the embossing bell  19  when the upper die part  17  and the lower die part  18  are closed. 
       FIG. 3 b    shows the state of the embossing stage  13  when the embossing anvil  28  has returned. For this purpose, the lower additional hydraulic unit  30  decreases the load on the lower pressure pin  32 , so that the embossing anvil  28  travels back with respect to the holder  27  in the direction of TDC so far that the fine-blanked workpiece  1  is seated in the holder  127  in an appropriately positioned manner. 
       FIG. 3 c    shows the workpiece  1  when clamped between the ejector  20  and the embossing anvil  28 , which is the prerequisite for starting the shaping process by way of the shaping punch  21 . 
       FIG. 3 d    shows the state after the burr mashing has been completed. 
     In  FIG. 3 e   , the upper additional hydraulic unit  24  has moved the shaping punch  21  back in the direction of bottom dead center with respect to the workpiece  1  on which the burr has been mashed. The workpiece  1  on which the burr has been mashed is partially detached, but not yet ejected. 
       FIG. 3 f    shows the state in which the forming stage is open, before the cross slide  16  is moved in so as to discharge the workpiece  1 . 
     As is shown in an enlarged illustration in  FIG. 4 , the shaping punch  21  is appropriately adapted to the inner contour  7  of the workpiece  1 , which is to say it has an ellipsoidal shape like the hole  9 . The head  33  of the shaping punch  21  is shaped as a spherical segment-shaped thickening  34 , which has defined slightly oversized dimensions compared to the inner contour  7  (holes  9 ). This thickening  34  on the shaping punch  21  forms a shaping region  35 . As soon as the workpiece  1  clamped between the ejector  20  and the embossing anvil  28  moves from the bottom to the top during the stroke, the shaping region  35  first presses the burr  5 . 1  on the inner contour outward in the direction of the burr  5  on the outer contour  2  and then engages the sheared edges  8  of the inner contour  7 , so that the inner contour  7  is widened along the circumference thereof by a defined degree by material displacement into the workplace interior, and the desired shape and dimensions are imparted to the inner contour  7  (see also  FIGS. 9 a  to 9 f   ). 
     The shaping punch  21  moreover has an embossing shoulder  36 , which is provided at a height H such that this is spaced vertically from the head end  45  of the shaping punch  21 , which is slightly greater than the thickness D of the workpiece  1 . 
     Once the sheared edge  8  has moved past the shaping region  35  during the stroke of the workpiece  1 , the inner contour  7  (hole  9 ) is widened by a defined degree and smoothed. The embossing shoulder  36  of the shaping punch  21  has seized the burr  5 . 1  on the inner contour and mashed it into the upper face of the workpiece  1 , whereby an embossing bead  47  is created on the sheared edge  8 . 
       FIGS. 5 and 6  show the design of the upper die part  17 . 
     The ejector  20 , which is vertically guided on the inner wall  37  of the embossing bell  19  and acted upon by the pressure pins  25  so as to carry out a relative movement with respect to the fixed embossing bell  19 , is inserted into the embossing bell  19  (see  FIG. 5 ). 
     The shape of the embossing bell  19  is adapted to the outer contour  2  of the workplace  1 , whereby the circumference of the outer contour  2  can be completely surrounded by the inner wall  37  of the embossing bell  19 . 
     The shaping punches  21  are attached to the upper embossing pressure plate  22  by screw bolts  38   a  and vertically guided in the ejector  20 , so that the shaping punches  21  are fixed on the upper embossing block  22   a  in a stationary manner. 
       FIG. 6  shows a section of the embossing bell  19  along line B-B in  FIG. 5 . An embossing shoulder  39  is provided on the inner wall  37  of the embossing bell  19  along the circumference thereof. This embossing shoulder  39  is designed so as to be able to mash the upwardly projecting burr  5  on the outer contour  2  as soon as the workpiece  1  seizes the upwardly projecting burr  5 . 1  during the stroke movement. The embossing shoulder  39  is provided at a height h that corresponds to the height H of the shaping punches  21 . This ensures that the mashing on the inner contour  7  and the outer contour  8  takes place simultaneously on the workpiece  1 . 
     The lower die part  18  is shown in  FIG. 7  in a depiction of revolution. The lower die part is composed of the embossing anvil  28 , a holder  27  for the embossing anvil  28 , an embossing positioning plate  40 , a shim  41 , the lower embossing pressure plate  29 , and an intermediate plate  42 . 
       FIG. 8  shows a section of the lower die part  18 . It is clearly apparent that the holder  27  is held on the intermediate plate  42  by way of the compression spring  31  in conjunction with the screw bolt  43 , and the intermediate plate  42  is held in a spring-loaded manner on the lower block  15  of the forming stage  13  by way of a compression spring  44  and a pin  43  (see also  FIG. 3 a   ). 
     The sequence of the method according to the invention is shown based on  FIGS. 9 a    to  9   e.    
       FIG. 9 a    is based on the open state of the device. The ejector  20  and the embossing anvil  28  are not shown in detail for the sake of simplicity. The shaping region  35  and the embossing shoulder  36  of the shaping punch  21 , and the embossing shoulder  39  of the embossing bell  19  are located non-engaged above the workpiece  1 . 
       FIG. 9 b    shows the state in which the workpiece  1  has reached the burr  5 . 1  on the sheared edge  8  of the inner contour  7  during the stroke. The upwardly projecting burr  5 . 1  is bent slightly outward in the direction of the outer contour  2  with the burr embossing radius GR by the spherical segment-shaped thickening  34 , so that the subsequent mashing of the burr  5 . 1  extends outwardly away from the inner contour  7 . 
     After another stroke of the workpiece  1 , the spherical segment-shaped thickening  34  of the shaping region  35  seizes the sheared edge  8  of the inner contour  7  and displaces material into the interior of the workpiece  1 . This creates a defined widening of the inner contour  7  on the workplace  1 . The defined widening is determined by the oversized dimension of the shaping region  35  in relation to the inner contour  7  or the hole  9  (see  FIG. 9 c   ). The widening of the inner contour is ended as soon as the sheared edge  8  no longer engages the shaping region  35 , which is to say as soon as the shaping region  35  of the shaping punch  21  has moved through the inner contour  7 . 
       FIG. 9 d    shows that the embossing shoulder  36  of the shaping punch  21  has mashed the slightly bent burr  5 . 1  on the workpiece  1  away from the inner contour  7 . The embossing shoulder  39  of the embossing bell  19  engages the burr  5  of the sheared edge  3  of the outer contour  2  simultaneously with the embossing shoulder  36  of the shaping punch  21 , so that the burr  5  is mashed on the workpiece  1  in the direction of the inner contour  7 . 
     If only one outer contour  2 , such as a disk, is to be produced, the simultaneous mashing is dispensed with of course, without departing from the method according to the invention. 
       FIG. 9 e    shows the state in which the shaping punch  21  carries out a return stroke movement counter to the stroke direction HR so as to demold the shaping punch  21  from the workpiece  1 . The shaping region  35  seizes the embossing bead  47  during the return stroke and flattens the same to the final dimensions.