Punch Hole Forming Method and Punch Hole Forming Device

Abstract

A punch hole forming method and a punch hole forming device that can suppress a decrease in the temperature of a workpiece due to a machining tool when a hole is formed by punching the workpiece using the machining tool. In the punch hole forming method, when a workpiece that is a plate-like member having a thickness of 0.01 mm or more and 1 mm or less is placed on a die, and a hole is formed by punching the workpiece in the thickness direction using a punch, the workpiece is kept at a temperature at which the workpiece can be punched at least during formation of the hole.

1 . A punch hole forming method comprising placing a workpiece that is a plate-like member having a thickness of 0.01 mm or more and 1 mm or less on a die, and forming a hole by punching the workpiece in a thickness direction using a punch,
 wherein the workpiece is kept at a temperature TO at which the workpiece can be punched at least during formation of the hole.   
     
     
         2 . The punch hole forming method according to  claim 1 , wherein a load applied by the punch to the workpiece while the workpiece at the temperature TO is being punched using the punch is smaller than or equal to a predetermined value. 
     
     
         3 . The punch hole forming method according to  claim 2 , wherein a load applied by the punch to the workpiece kept at the temperature TO while a hole is formed in the workpiece using the punch is 10% or more and 30% or less of a load required to form a hole in the workpiece at room temperature using the punch. 
     
     
         4 . The punch hole forming method according to  claim 1 , wherein the temperature TO is 300° C. or higher and 950° C. or lower. 
     
     
         5 . The punch hole forming method according to  claim 1 , wherein the workpiece is kept at the temperature TO by placing the workpiece on the die heated to a temperature TD. 
     
     
         6 . The punch hole forming method according to  claim 5 , wherein the workpiece is kept at the temperature TO by punching the workpiece using the punch heated to a temperature TP. 
     
     
         7 . The punch hole forming method according to  claim 1 , wherein an aspect ratio defined as a ratio of a thickness of the workpiece to a diameter of the hole, thickness/diameter, is set to 2 or more and 30 or less. 
     
     
         8 . The punch hole forming method according to  claim 7 , wherein the diameter of the hole is 1 mm or less. 
     
     
         9 . The punch hole forming method according to  claim 1 , wherein a plurality of the holes are formed in the workpiece. 
     
     
         10 . The punch hole forming method according to  claim 1 , wherein the workpiece is made of a heat-resistant metal material selected from ferrite-based stainless steel, austenite-based stainless steel, and martensite-based stainless steel. 
     
     
         11 . The punch hole forming method according to  claim 1 , wherein at least one of the punch and the die is made of a superhard material containing at least one of ceramic and tungsten. 
     
     
         12 . The punch hole forming method according to  claim 1 , wherein a coolant gas is blasted onto the punch after the workpiece has been punched using the punch. 
     
     
         13 . The punch hole forming method according to  claim 12 , wherein the coolant gas is at least one of carbonic acid gas, nitrogen, and argon. 
     
     
         14 . The punch hole forming method according to  claim 1 ,
 wherein the punch includes:
 a punch main body having a plate shape with a predetermined thickness: 
 a punching blade that protrudes and extends from an opposed face of the punch main body opposed to the workpiece and that is used to form a hole in the workpiece; and 
 a stripper member including a base portion that is located on a face facing in a direction opposite to a protruding direction of the punching blade out of two opposite faces of the punch main body, and a stripper pin that extends from the base portion, passes through the punch main body in the protruding direction of the punching blade, and has a length larger than a thickness of the punch main body, 
   wherein the stripper pin is retracted so as not to protrude from the opposed face while the workpiece is being punched using the punch, and   after the workpiece has been punched using the punch, a leading end of the stripper pin protrudes from the opposed face and presses the workpiece, and the punching blade is removed from the workpiece together with the punch main body.   
     
     
         15 . A punch hole forming device for forming a hole in the workpiece using the punch hole forming method according to  claim 1 , the device comprising:
 a die on which the workpiece is to be placed;   a punch for forming a hole by punching the workpiece placed on the die in a thickness direction; and   a control unit that performs control to keep the workpiece at a temperature TO at which the workpiece can be punched while the hole is being formed.   
     
     
         16 . The punch hole forming method according to  claim 2 , wherein the temperature TO is 300° C. or higher and 950° C. or lower. 
     
     
         17 . The punch hole forming method according to  claim 3 , wherein the temperature TO is 300° C. or higher and 950° C. or lower. 
     
     
         18 . The punch hole forming method according to  claim 2 , wherein the workpiece is kept at the temperature TO by placing the workpiece on the die heated to a temperature TD. 
     
     
         19 . The punch hole forming method according to  claim 3 , wherein the workpiece is kept at the temperature TO by placing the workpiece on the die heated to a temperature TD. 
     
     
         20 . The punch hole forming method according to  claim 4 , wherein the workpiece is kept at the temperature TO by placing the workpiece on the die heated to a temperature TD.