Method for bending the machine bed of a stamping press, and stamping press

Abstract

A method for warping the machine bed of a punching press, which machine bed has an aperture for carrying away punching parts and rubbish, compensates at least partially for a bending of the machine bed caused by the punching force during the punching operation. Thereby, forces acting transverse to the punching direction are introduced into the machine bed and/or forces acting transverse to the punching force direction are produced inside the machine bed, by means of which the machine bed warps in the direction towards the press ram and indeed such that it warps stronger in the area adjacent to the aperture than in the areas adjacent to its longitudinal sides. By the method, apertured machine beds of punching presses can, with very little expenses on the equipment side, be spatially pre-deformed in order to compensate at least partially bendings caused by punching forces.

What is claimed is: 
     
         1 . A method for warping a machine bed of a punching press to compensate at least partially a bending caused by the punching force during punching operation, wherein the machine bed has an aperture for carrying away punching parts and rubbish,
 wherein forces acting transverse to the punching force direction are introduced into the machine bed or are created within the machine bed for warping the machine bed in the direction towards the press ram such that the machine bed is warped stronger in the area adjacent to the aperture than in the areas adjacent to the longitudinal sides.   
     
     
         2 . The method according to  claim 1 , wherein the machine bed with tie-rods extending in its longitudinal direction is set under compressive stress in its lower area for warping the same in the direction towards the press ram. 
     
     
         3 . The method according to  claim 2 , wherein the tie-rods are arranged such that they cross the machine bed in its lower area. 
     
     
         4 . The method according to  claim 2 , wherein on both sides of the aperture of the machine bed, in particular symmetrical to both sides of the aperture, in each case a tie-rod is arranged such that the tie-rod in each case has a smaller distance to the aperture than to the respective longitudinal side of the machine bed. 
     
     
         5 . The method according to  claim 1 , wherein a temperature gradient is produced within the machine bed or a supporting structure for the lower tool parts built with the machine bed, by means of which the machine bed warps in the direction towards the press ram. 
     
     
         6 . The method according to  claim 5 , wherein the temperature gradient is produced by heating the machine bed in the area of its side facing the press ram. 
     
     
         7 . The method according to  claim 6 , wherein the machine bed near to the boundaries of the aperture is heated stronger than near to the longitudinal sides. 
     
     
         8 . The method according to  claim 5 , wherein the temperature gradient is produced by cooling the machine bed in the area of its side facing away from the press ram. 
     
     
         9 . The method according to  claim 8 , wherein the machine bed is near to the boundaries of the aperture is cooled stronger than near to the longitudinal sides. 
     
     
         10 . The method according to  claim 5 , wherein flow channels arranged within the machine bed are flown through by a heated or cooled gaseous or liquid medium for producing the temperature gradient. 
     
     
         11 . The method according to  claim 10 , wherein heated lubricating oil of a lubricating oil circuit of the press is passed through the flow channels. 
     
     
         12 . The method according to  claim 5 , wherein electrical heating elements arranged within the machine bed are charged with electric current for producing the temperature gradient. 
     
     
         13 . The method according to  claim 5 , wherein a clamping plate arranged on the machine bed is present which is heated for warping the machine bed in the direction towards the press ram as a consequence of a heating of it by the clamping plate on its side facing the ram and/or for warping the machine bed in the direction towards the press ram as a consequence of an introduction of shear forces produced by a thermal expansion of the clamping plate into the side of the machine bed facing the ram. 
     
     
         14 .- 40 . (canceled) 
     
     
         41 . The method according to  claim 5 , wherein a clamping plate arranged on the machine bed is present and a heating device arranged between the machine bed and the clamping plate, which is heated for warping the machine bed in the direction towards the press ram as a consequence of a heating of it by the heating device on its side facing the ram and/or for warping the machine bed in the direction towards the press ram as a consequence of a heating of the clamping plate by the heating device and by an introduction of shear forces produced by a thermal expansion of the clamping plate into the side of the machine bed facing the ram. 
     
     
         42 . The method according to  claim 1 , wherein the warp of the machine bed is adjusted depending on parameters of the punching process, in particular depending on a calculated or measured maximal punching force, and in particular, wherein the warp is adjusted during the intended operation of the press. 
     
     
         43 . A punching press for performing the method according to  claim 1 , with a machine bed and with a press ram working against the machine bed,
 wherein means are present for warping the machine bed in the direction towards the press ram by an introduction of forces acting transverse to the punching force direction into the machine bed and/or by producing forces acting transverse to the punching force direction within the machine bed,   wherein the machine bed has an aperture for carrying away punching parts and rubbish and the means for warping the machine bed are designed such that they warp the machine bed stronger in the area adjacent to the aperture than in the areas adjacent to the longitudinal sides of the machine bed,   and wherein the means for warping the machine bed comprise tie-rods extending in longitudinal direction of the machine bed, by means of which the machine bed can be set under compressive stress in its lower area for warping the machine bed in the direction towards the press ram.   
     
     
         44 . The punching press according to  claim 43 , wherein the tie-rods cross the machine bed in its lower area. 
     
     
         45 . The punching press according to  claim 43 , wherein on both sides of the aperture of the machine bed in each case a tie-rod is arranged such that in each case the tie-rod has a smaller distance to the aperture than to the respective longitudinal side of the machine bed. 
     
     
         46 . The punching press according to  claim 45 , wherein the both tie-rods are arranged symmetrically to both sides of the aperture. 
     
     
         47 . A punching press for performing the method according to  claim 1 , with a machine bed and with a press ram working against the machine bed, wherein means are present for warping the machine bed in the direction towards the press ram by introducing forces acting transverse to the punching force direction into the machine bed and/or by producing forces acting transverse to the punching force direction within the machine bed,
 wherein the machine bed has an aperture for carrying away punching parts and rubbish and the means for warping the machine bed are designed such that they warp the machine bed in the area adjacent to the aperture stronger than in the areas adjacent to the longitudinal sides of the machine bed,   wherein the means for warping the machine bed are designed for producing a temperature gradient within the machine bed or a supporting structure for the lower tool parts built with the machine bed, respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram,   wherein the means for warping the machine bed comprise flow channels arranged within the machine bed, which can be flown through by a heated or cooled gaseous or liquid medium during the intended operation of the press for producing the temperature gradient, and   wherein the press comprises a lubricating oil circuit and the means for warping the machine bed comprise arrangements, by means of which heated lubricating oil of the lubricating oil circuit can be passed through the flow channels during the intended operation of the press.   
     
     
         48 . The punching press according to  claim 47 , wherein the means for warping the machine bed are designed for heating the machine bed in the area of its side facing the press ram. 
     
     
         49 . The punching press according to  claim 48 , wherein the means for warping the machine bed are designed to heat the machine bed in the area of its side facing the press ram stronger near to the boundaries of the aperture than near to its longitudinal sides. 
     
     
         50 . The punching press according to  claim 47 , wherein the means for warping the machine bed are designed to cool the machine bed in the area of its side facing away from the press ram. 
     
     
         51 . The punching press according to  claim 50 , wherein the means for warping the machine bed are designed to cool the machine bed in the area of its side facing away from the press ram stronger near to the boundaries of the aperture than near to its longitudinal sides. 
     
     
         52 . The punching press according to  claim 47 , wherein the means for warping the machine bed comprise electrical heating elements arranged within the machine bed, which can be charged by electric current during the intended operation of the press for producing the temperature gradient. 
     
     
         53 . The punching press according to  claim 47 , wherein on both sides of the aperture of the machine bed in each case one or more flow channels and/or electrical heating elements are arranged within the machine bed such that, per side, the sum of the distances of the flow channels and/or the heating elements to the aperture is smaller than the sum of the distances of the flow channels and/or heating elements to the respective longitudinal sides of the machine bed. 
     
     
         54 . The punching press according to  claim 53 , wherein the flow channels and/or the heating elements are arranged symmetrically to both sides of the aperture. 
     
     
         55 . A punching press for performing the method according to  claim 1 , with a machine bed and with a press ram working against the machine bed,
 wherein means are present for warping the machine bed in the direction towards the press ram by introducing forces acting transverse to the punching force direction into the machine bed and/or by producing forces acting transverse to the punching force direction within the machine bed,   wherein the machine bed has an aperture for carrying away punching parts and rubbish and the means for warping the machine bed are designed such that they warp the machine bed in the area adjacent to the aperture stronger than in the areas adjacent to the longitudinal sides of the machine bed,   wherein the means for warping the machine bed are designed for the production of a temperature gradient within the machine bed or a supporting structure for the lower tool parts built with the machine bed, respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram, and   wherein a clamping plate arranged on the machine bed is present which can be heated by the means for warping the machine bed during the intended operation of the press for producing the temperature gradient by heating the machine bed on its side facing the ram by the clamping plate.   
     
     
         56 . A punching press for performing the method according to  claim 1 , with a machine bed and with a press ram working against the machine bed,
 wherein means are present for warping the machine bed in the direction towards the press ram by introducing forces acting transverse to the punching force direction into the machine bed and/or by producing forces acting transverse to the punching force direction within the machine bed,   wherein the machine bed has an aperture for carrying away punching parts and rubbish and the means for warping the machine bed are designed such that they warp the machine bed in the area adjacent to the aperture stronger than in the areas adjacent to the longitudinal sides of the machine bed,   wherein the means for warping the machine bed are designed for the production of a temperature gradient within the machine bed or a supporting structure for the lower tool parts built with the machine bed, respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram, and   wherein a clamping plate arranged on the machine bed is present which can be heated by the means for warping the machine bed during the intended operation of the press and which is connected with the machine bed such that it can transfer shear forces to the machine bed for warping the machine bed in the direction towards the press ram as a consequence of an introduction of shear forces produced by a thermal expansion of the clamping plate into the side of the machine bed facing the press ram.   
     
     
         57 . The punching press according to  claim 56 , wherein a thermal insulation layer is present between the clamping plate and the machine bed for reducing a heat transfer from the clamping plate to the machine bed. 
     
     
         58 . The punching press according to  claim 57 , wherein the thermal insulation layer is present in the areas, which adjoin the longitudinal sides of the clamping plate or of the machine bed, respectively, between the clamping plate and the machine bed and in the areas, which adjoin the aperture, a layer between the clamping plate and the machine bed is present which has an essentially better thermal conductivity for promoting a heat transfer from the clamping plate to the machine bed in these areas. 
     
     
         59 . The punching press according to  claim 55 , wherein the clamping plate can be heated by the means for warping the machine bed during the intended operation of the press such that it is warmer in the areas which adjoin the aperture than in the areas which adjoin the longitudinal sides. 
     
     
         60 . A punching press for performing the method according to  claim 1 , with a machine bed and with a press ram working against the machine bed,
 wherein means are present for warping the machine bed in the direction towards the press ram by introducing forces acting transverse to the punching force direction into the machine bed and/or by producing forces acting transverse to the punching force direction within the machine bed,   wherein the machine bed has an aperture for carrying away punching parts and rubbish and the means are designed for warping the machine bed such that they warp the machine bed in the area adjacent to the aperture stronger than in the areas adjacent to the longitudinal sides of the machine bed,   wherein the means for warping the machine bed are designed for the production of a temperature gradient within the machine bed or a supporting structure for the lower tool parts built with the machine bed, respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram, and   wherein a clamping plate arranged on the machine bed is present and wherein the means for warping the machine bed comprise a heating device arranged between the machine bed and the clamping plate, which can be operated during the intended operation of the press for warping the machine bed as a consequence of a heating of it on its side facing the ram.   
     
     
         61 . A punching press for performing the method according to  claim 1 , with a machine bed and with a press ram working against the machine bed,
 wherein means are present for warping the machine bed in the direction towards the press ram by introducing forces acting transverse to the punching force direction into the machine bed and/or by producing forces acting transverse to the punching force direction within the machine bed,   wherein the machine bed has an aperture for carrying away punching parts and rubbish and the means for warping the machine bed are designed such that they warp the machine bed in the area adjacent to the aperture stronger than in the areas adjacent to the longitudinal sides of the machine bed,   wherein the means for warping the machine bed are designed for the production of a temperature gradient within the machine bed or a supporting structure for the lower tool parts built with the machine bed, respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram, and   wherein a clamping plate arranged on the machine bed is present, which is connected with the machine bed such that it can transfer shear forces to the machine bed, and wherein the means for warping the machine bed comprise a heating device arranged between the machine bed and the clamping plate, which can be operated during the intended operation of the press for warping the machine bed in the direction towards the press ram as a consequence of an introduction of shear forces produced by a thermal expansion of the clamping plate into the side of the machine bed facing the ram.   
     
     
         62 . The punching press according to  claim 60 , wherein the heating device arranged between the machine bed and the clamping plate is designed such that with it the areas of the machine bed or of the clamping plate, respectively, which adjoin the aperture can be heated stronger than the areas of the machine bed or of the clamping plate, respectively, which adjoin their longitudinal sides. 
     
     
         63 . The punching press according to  claim 43 , wherein the means for warping the machine bed are built adjustable, in particular during the intended operation of the press, for enabling a specific adjustment of the warp of the machine bed. 
     
     
         64 . The punching press according to  claim 43 , wherein the punching press comprises a press control, by means of which the warp of the machine bed, in particular automatically, is adjustable depending on parameters of the punching process, in particular depending on a calculated or measured maximal punching force, and in particular is adjustable during the intended operation of the press.