Deep-drawing press and method for deep-drawing sheet-metal workpieces

Abstract

A deep-drawing press includes a one-piece drawing cushion, an arrangement of cushion cylinders and a control unit. The overall performance of the press is increased by the possibility of using both large and small tools. The position of the drawing cushion is controlled during the forming process.

We claim:  
     
         1 . A deep-drawing press with a table drawing cushion and a tool arrangement comprising at least one upper die ( 2 ) secured to a press ram ( 1 ), at least one blank holder ( 4 ) supported by cushion bolts ( 7 ), at least one lower die ( 5 ) in connection with the press table ( 6 ), a one-piece drawing cushion ( 8 ), a plurality of outer cushion cylinders ( 9 ) arranged at least in corner areas of the drawing cushion ( 8 ), and, a control unit ( 16 ) for applying pressure to individual ones of the cushion cylinders ( 9 ) in connection with distance measuring elements ( 13 ,  14 ) and pressure measuring elements ( 15 ).  
     
     
         2 . The deep-drawing press according to  claim 1 , wherein at least one inner cushion cylinder ( 10 ) is arranged below the drawing cushion ( 8 ).  
     
     
         3 . The deep-drawing press according to  claim 2 , wherein the control unit ( 16 ) causes an application of pressure to the inner and outer cushion cylinders ( 9 ,  10 ) in response to distance and/or pressure signals of the tool arrangement.  
     
     
         4 . The deep-drawing press according to  claim 2 , wherein a ram path (sst) is detected by the distance measuring elements ( 13 ), a drawing cushion path (ski) is detected by the distance measuring elements ( 14 ), and a cushion cylinder pressure (p) is detected by the pressure measuring elements ( 15 ), wherein, after a set-value/actual-value comparison, measured values of the drawing cushion path (ski), of the ram path (sst), and the pressure signals (p) serve to control a stroke control unit, an x-tilt control unit, a y-tilt control unit, and synchronization means whose output signals control valves of the cushion cylinders ( 9 ,  10 ).  
     
     
         5 . The deep-drawing press according to  claim 1 , wherein the tool arrangement is a transfer tool ( 17 ) with at least one deep-drawing tool ( 2 ,  5 ) in a boundary area.  
     
     
         6 . A method of deep-drawing sheet-metal workpieces in the deep-drawing press according to  claim 2 , wherein, in a case of low forming forces, only outer cushion cylinders ( 9 ), which are effective in the corner areas of the one-piece drawing cushion ( 8 ), have pressure applied thereto, while the inner cushion cylinder(s) ( 10 ) has/have no pressure applied thereto.  
     
     
         7 . The deep-drawing method according to  claim 6 , wherein, depending on a forming force, the outer and inner cushion cylinders ( 9 ,  10 ) have pressure applied thereto in combination.  
     
     
         8 . The deep-drawing method according to  claim 6 , wherein force and position control is effected for parallel or non-parallel control of the drawing cushion relative to the table or the ram.