Method And Apparatus For Determining The Thickness Or The Springback Of A Workpiece Bent By A Press Brake

Abstract

A method and apparatus for determining the thickness of a workpiece or its springback in a press brake is described. The method includes the steps of detecting the deformation or strain in the punch ( 1 ) and/or the die ( 4 ) during bending, and translating it into an electric signal, by suitable devices located directly on the working parts; possibly amplifying the electric signal by an amplifier ( 5 ) and transmitting the signal to a press brake controller ( 6 ), which processes the collected data and corrects the angle of the workpiece being bent. The process allows to determine the springback of the bent sheet, thereby increasing processing accuracy.

1 . A method for determining the thickness or the springback of a workpiece bent by a press brake, said workpiece being placed between the die ( 4 ) and the punch ( 1 ) of the press brake, characterized in that it comprises the steps of: 
 detecting the deformation or strain in the punch ( 1 ) and/or the die ( 4 ) and translating it into an electric signal; said detection occurring at the start of the process, during bending and release of the punch ( 4 );    amplifying the electric signal by means of an amplifier ( 5 );    transmitting the electric signal to a controller ( 6 ) of the press brake, which processes the collected data and corrects the angle of the workpiece being bent.    
   
   
       2 . A method as claimed in  claim 1 , characterized in that, based on the data collected at the start of the bending operation, the controller ( 6 ) corrects the thickness in the calculation of the penetration required to obtain the desired bend in the workpiece.  
   
   
       3 . A method as claimed in  claim 1 , characterized in that, based on the data collected in the releasing step, the controller ( 6 ) extrapolates and calculates the error in full springback conditions, without the workpiece being actually released, and corrects the bend on the same workpiece, thereby avoiding any error due to correcting the bend on a released workpiece.  
   
   
       4 . A method as claimed in  claim 1 , characterized in that the deformation or strain in the punch ( 1 ) and/or the die ( 4 ) is detected by means of at least one strain gage located on said punch ( 1 ) and/or die ( 4 ).  
   
   
       5 . An apparatus for determining the thickness or the springback of a workpiece bent by a press brake, characterized in that it comprises: 
 at least one device ( 2 ,  3 ) for measuring the deformation and/or strain in the punch ( 1 ) and/or die ( 4 ), said device being mounted to the punch ( 1 ) and/or to the die ( 4 ) of the press brake;    a signal amplifier ( 5 ), which amplifies the signal received by the deformation and/or strain measuring devices ( 2 ,  3 );    a controller ( 6 ) for receiving the amplified signal.    
   
   
       6 . A device as claimed in  claim 5 , characterized in that the controller ( 6 ) processes the data collected at the start of the bending operation and thereby appropriately corrects the thickness in the calculation of the penetration required to obtain the desired bend in the workpiece.  
   
   
       7 . A device as claimed in  claim 5 , characterized in that the controller ( 6 ) processes the data collected in the releasing step after the first bend and thereby appropriately corrects the bend angle in the subsequent bend.  
   
   
       8 . A device as claimed in  claim 3 , characterized in that the device ( 2 ,  3 ) for measuring the deformation and/or strain in the punch ( 1 ) and/or die ( 4 ) is a strain gage.