Swivel bending machine for creating an open hem on a sheet and sheet bending method

Abstract

A swivel bending machine and method produces a hollow fold on a sheet with a lower beam for supporting the sheet, an upper beam with a wedge-shaped bending edge for clamping the sheet between the upper beam and the lower beam, a rotatable or pivotable bending beam for bending the sheet section of the sheet protruding between the upper beam and the lower beam in a first bending step along the wedge-shaped bending edge into an acute angle, and a movement device for moving the wedge-shaped bending edge out of the sheet section pre-bent into an acute angle. The swivel bending machine further bends the sheet section into a hollow fold in a second bending step with further actuation of the bending beam between the bending beam and the lower beam, while the sheet is fixed against the lower beam by the wedge-shaped bending edge.

What is claimed is: 
     
         1 . A swivel bending machine ( 100 ) for producing a hollow fold on a sheet ( 103 ) with:
 a lower beam ( 101 ) for supporting the sheet ( 103 ),   an upper beam ( 105 ) with a wedge-shaped bending edge ( 107 ) for clamping the sheet ( 103 ) between the upper beam ( 105 ) and the lower beam ( 101 ),   a rotatable or pivotable bending beam ( 109 ) for bending the sheet section ( 115 ) of the sheet ( 103 ) protruding be-tween the upper beam and the lower beam in a first bending step along the wedge-shaped bending edge ( 107 ) to an acute angle, and   a movement device ( 111 ) for moving the wedge-shaped bending edge ( 107 ) out of the sheet section ( 115 ) pre-bent to an acute angle,
 wherein the swivel bending machine ( 100 ) is set up to further bend the sheet section ( 115 ) pre-bent into an acute angle into a hollow fold ( 125 ) in a second bending step with further actuation of the bending beam ( 109 ) between the bending beam ( 109 ) and the lower beam ( 101 ), while the sheet ( 103 ) is fixed against the lower beam by the wedge-shaped bending edge ( 107 ). 
   
     
     
         2 . The swivel bending machine ( 100 ) of  claim 1 , wherein the movement device ( 111 ) comprises a displacement device ( 123 ) for linearly pulling out the wedge- shaped bending edge ( 107 ). 
     
     
         3 . The swivel bending machine ( 100 ) of  claim 1 , wherein the movement device ( 111 ) comprises a rotating device ( 113 ) for turning out or swiveling out the wedge-shaped bending edge ( 107 ). 
     
     
         4 . The swivel bending machine ( 100 ) of  claim 3 , wherein the rotating device ( 113 ) comprises a plurality of bending edges ( 107 - 1 ,  107 - 2 ). 
     
     
         5 . The swivel bending machine ( 100 ) of  claim 1 , wherein the bending beam ( 109 ) comprises a bending bar ( 121 ) for bending the sheet section ( 115 ). 
     
     
         6 . The swivel bending machine ( 100 ) of  claim 5 , wherein the bending bar ( 121 ) or the bending beam ( 109 ) comprises a crowning ( 127 ) for uniformly producing the hollow fold ( 125 ). 
     
     
         7 . The swivel bending machine ( 100 ) of  claim 6 , wherein the bending bar ( 121 ) has a profile which is vertically crowned in the longitudinal direction of the machine. 
     
     
         8 . A sheet bending method for producing a hollow fold ( 125 ) on a sheet ( 103 ) with a swivel bending machine of  claim 1 , comprising the steps of:
 (A) Placing a sheet ( 103 ) with a sheet section ( 115 ), which is initially to be pre-bent to an acute angle, on a lower beam ( 101 ) of the swivel bending machine ( 100 ),   (B) clamping of the sheet between an upper beam ( 105 ) having a wedge-shaped bending edge ( 107 ) and the lower beam ( 101 ),   (C) bending of a sheet section ( 115 ) protruding between the upper beam and the lower beam by means of the bending beam ( 109 ) in a first bending step along the wedge-shaped bending edge ( 107 ) to an acute angle,   (D) moving the wedge-shaped bending edge ( 107 ) out of the sheet section ( 115 ) pre-bent to an acute angle, and   (E) further bending of the sheet section ( 115 ) in a second bending step into a hollow fold ( 125 ) by further swiveling of the bending beam ( 109 ), while the sheet ( 103 ) is fixed against the lower beam ( 101 ) by means of the wedge-shaped bending edge ( 107 ).   
     
     
         9 . The sheet bending method of  claim 8 , wherein the wedge-shaped bending edge ( 107 ) is moved out of the pre-bent sheet section ( 115 ) in the opposite wedge direction by a movement device ( 111 ). 
     
     
         10 . The sheet bending method of  claim 9 , wherein the wedge-shaped bending edge ( 107 ) is pivoted out or pulled out of the pre-bent sheet section ( 115 ). 
     
     
         11 . The sheet bending method of  claim 8 , wherein a deflection of the bending beam ( 109 ) and or the bending bar ( 121 ) during the first or second bending step is compensated by a crowning ( 127 ).