Method and apparatus for detecting mis-stripping in a punch press machine

Abstract

A method and apparatus for detecting the presence of mis-stripping uses a sensor function section free from operation sensibility variation or destruction due to vibration, impact or the like. Only a ram head in a punch press is provided in an electrically insulated state on the machine side and a low voltage is applied to the ram head. Grounding and conduction of the ram head to the machine side through punch tools is detected when the ram head is in contact with the punch tools, nonconduction is detected when the ram head and punch tools are not in contact, and the nonconduction time is determined to be mis-stripping.

What is claimed is:  
     
         1 . A method for detecting mis-stripping in a punch press machine, comprising; 
 operating a punch press having a ram head to strike a punch tool, the ram head being electrically insulated from the punch press machine;    applying a weak current to the ram head, and determining the presence or absence of mis-stripping by detecting contact or non contact between said ram head and punch tool by detecting presence or absence of flow of said current.    
     
     
         2 . The method for detecting mis-stripping in a punch press machine as defined in    claim 1   , wherein said weak current is a direct current of about 24V.  
     
     
         3 . A method for detecting mis-stripping in a punch press machine, comprising: 
 providing a ram head of a punch press that is electrically insulated from the punch press machine; applying an electric current of low voltage to the ram head, at a return upward stop position of a punch tool, detecting grounding and conduction of the ram head to the machine through the punch tool when said ram head is in contact with the punch tool, and detecting non conduction when the ram head and the punch tool is not in contact, where the non conduction time is judged to be mis-stripping.    
     
     
         4 . The method of detecting mis-stripping in a punch press machine as defined in    claim 3   , wherein said electric current is of about 24V.  
     
     
         5 . A detection apparatus for detecting mis-stripping in a punch press machine having a ram for contacting punch tools, comprising: 
 a ram head having bores therethrough;    fasteners passing through said bores and securing the ram head to the ram;    electrical insulation disposed between the ram and the ram head;    further electrical insulation disposed in the bores between the fasteners and the ram head; and    an electrical conductive member conductively attached to the ram head;    such that when the ram head contacts the punch tools an electric current supplied to the electrically conductive member will flow to the punch tools.    
     
     
         6 . A detection apparatus for detecting mis-stripping in a punch press machine having a ram for contacting punch tools as defined in    claim 5   , wherein the fasteners are threaded bolts passing through the bores of the ram head and threadedly engaged in screw-holes in the ram.  
     
     
         7 . A detection apparatus for detecting mis-stripping in a punch press machine as defined in    claim 6   , wherein the screw holes are provided in a concave mount seat of the ram and the ram head seats in said concave mount seat.