Pressing Machine, Pressing Method, and Punched Article

Abstract

A press working apparatus is provided with a first working unit and a second working unit 14 . In the first working unit, a first stage is performed for forming a half-blanked portion 15 with a projecting shape at a region where a through hole P is to be formed in a sheet W. In the second working unit 14 , a second stage S 2 is performed in which the half-blanked portion 15 is blanked from the sheet W by a second punch 26 and a second die 23 . Also in the second stage S 2 , when a blanked body is blanked from the sheet W, shaving work is performed with respect to a side wall surface Pa on a region of the sheet W where the blanked body has been blanked.

1 . A press working apparatus, which performs blanking work on a sheet, comprising: 
 a first working unit having a first upper die and a first lower die, wherein    at least one of the first upper die and the first lower die is mobile in the vertical direction with respect to the other, with the first upper die fixedly attached with at least one among an opposing first punch and a first die, and the first lower die fixedly attached with the other among the first punch and the first die, and    a negative clearance is set between the first punch and the first die as viewed from the vertical direction, and half-blanking work is performed on the sheet by relatively moving the first punch and the first die in the vertical direction; and    a second working unit having a second upper die and a second lower die, wherein    at least one of the second upper die and the second lower die is mobile in the vertical direction with respect to the other, with the second upper die fixedly attached with at least one among a second punch and a second die having a paired relationship, and the second lower die fixedly attached with the other among the second punch and the second die, and    a positive clearance is set between the second punch and the second die as viewed from the vertical direction, and when a half-blanked portion that was formed in the sheet by half-blanking work performed by the first working unit is blanked to become a blanked body by the second punch, a blanked surface is formed along a blanking direction on a region where the blanked body is blanked from the sheet, and at least a portion of the blanked surface is subjected to shaving work performed by the second punch.    
   
   
       2 . The press working apparatus according to  claim 1 , wherein the second punch is structured so as to achieve a form wherein a cross-sectional shape for the second punch when cut in a direction orthogonal to the vertical direction is a similar and enlarged version of a cross-sectional shape for the first punch when cut in a direction orthogonal to the vertical direction.  
   
   
       3 . The press working apparatus according to  claim 2 , wherein the second punch is structured such that if the cross-sectional shape for the second punch when cut in a direction orthogonal to the vertical direction overlaps in the vertical direction with the cross-sectional shape for the first punch when cut in a direction orthogonal to the vertical direction, then there is a distance dimension of 0.01 mm to 0.3 mm between adjacent outer peripheral regions with mutually similar shapes.  
   
   
       4 . The press working apparatus according to any one of  claims 1  to  3 , wherein the first die is formed with a through hole running therethrough that extends in the vertical direction, and the second punch is structured such that the cross-sectional shape for the second punch when cut in a direction orthogonal to the vertical direction is a similar and enlarged shape of a hole shape of the through hole when the first die when is cut in a direction orthogonal to the vertical direction.  
   
   
       5 . The press working apparatus according to  claim 4 , wherein the second punch is structured such that if the cross-sectional shape for the second punch when cut in a direction orthogonal to the vertical direction overlaps in the vertical direction with the cross-sectional shape for the first die when cut in a direction orthogonal to the vertical direction, then there is a distance dimension of 0.01 mm to 0.3 mm between an outer peripheral region of the cross section of the second punch and an inner peripheral region of the cross section of the first die, which have a mutually similar relationship.  
   
   
       6 . A press working apparatus, which performs blanking work on a sheet, comprising: 
 a first working unit having a first upper die and a first lower die, wherein    at least one of the first upper die and the first lower die is mobile in the vertical direction with respect to the other, with the first upper die fixedly attached with at least one among an opposing first punch and a first die, and the first lower die fixedly attached with the other among the first punch and the first die, and    a negative clearance is set between the first punch and the first die as viewed from the vertical direction, and half-blanking work is performed on the sheet by relatively moving the first punch and the first die in the vertical direction; and    a second working unit having a second upper die and a second lower die, wherein    at least one of the second upper die and the second lower die is mobile in the vertical direction with respect to the other, with the second upper die fixedly attached with at least one among a second punch and a second die having a paired relationship, and the second lower die fixedly attached with the other among the second punch and the second die, and    a positive clearance is set between the second punch and the second die as viewed from the vertical direction, and when a half-blanked portion that was formed in the sheet by half-blanking work performed by the first working unit is blanked to become a blanked body by the second punch, a blanked surface is formed along a blanking direction on the blanked body, and at least a portion of the blanked surface is subjected to shaving work performed by the second die.    
   
   
       7 . The press working apparatus according to  claim 6 , wherein the first die and the second die are respectively formed with insertion holes running therethrough in the vertical direction, and the second die is structured so as to achieve a form wherein a hole shape of the insertion hole when the second die is cut in a direction orthogonal to the vertical direction is a similar and scaled-down version of a hole shape of the insertion hole when the first die is cut in a direction orthogonal to the vertical direction.  
   
   
       8 . The press working apparatus according to  claim 7 , wherein the second die is structured such that if a cross-sectional shape for the second die when cut in a direction orthogonal to the vertical direction overlaps in the vertical direction with a cross-sectional shape for the first die when cut in a direction orthogonal to the vertical direction, then there is a distance dimension of 0.01 mm to 0.3 mm between an outer peripheral region of a cross section of the second die and an inner peripheral region of a cross section of the first die, which have a mutually similar relationship.  
   
   
       9 . The press working apparatus according to any one of  claims 1  to  8 , wherein the first working unit is structured such that if the first punch is made to relatively approach the first die, then the first punch is made to approach up to a position that is separated only by a distance dimension that is 10% to 50% of a thickness dimension of the sheet.  
   
   
       10 . The press working apparatus according to any one of  claims 1  to  9 , wherein the first punch is formed such that a width dimension of the negative clearance is a width dimension that is 1% to 15% of the thickness dimension of the sheet.  
   
   
       11 . The press working apparatus according to any one of  claims 1  to  10 , wherein the second punch is fixedly attached with the second lower die if the first punch is fixedly attached with the first upper die, and the second punch is fixedly attached with the second upper die if the first punch is fixedly attached with the first lower die.  
   
   
       12 . The press working apparatus according to any one of  claims 1  to  11 , wherein the second punch is formed such that a width dimension of the positive clearance is a width dimension that is 0.3% to 8% of the thickness dimension of the sheet.  
   
   
       13 . The press working apparatus according to any one of  claims 1  to  12 , wherein at least one among an end edge portion on a side facing the sheet in the first punch and an inner-side edge portion on a side facing the sheet in the first die is subjected to chamfering work so as to have a curved surface.  
   
   
       14 . The press working apparatus according to  claim 13 , wherein the curved surface formed on at least one among the end edge portion on a side facing the sheet in the first punch and the inner-side edge portion on a side facing the sheet in the first die is formed so as to achieve an arc shape, which has a curvature radius with a length dimension that is equal to or less than 7.5% of the thickness dimension of the sheet when the first punch and the first die are cut in the vertical direction.  
   
   
       15 . The press working apparatus according to any one of  claims 1  to  14 , wherein an end edge portion on a side facing the sheet in the second punch is subjected to chamfering work so as to have a curved surface.  
   
   
       16 . The press working apparatus according to  claim 15 , wherein the curved surface of the end edge portion on a side facing the sheet in the second punch is formed so as to achieve an arc shape, which has a curvature radius with a length dimension that is equal to or less than 7.5% of the thickness dimension of the sheet when the second punch is cut in the vertical direction.  
   
   
       17 . A blanked product manufactured by blanking a blanked body from a sheet using a press working apparatus according to any one of  claims 1  to  16 .  
   
   
       18 . A press working method, which performs blanking work on a sheet, comprising: 
 a first stage where a first punch and a first die in a paired relationship are used to perform half-blanking work on a region where a blanked body is to be blanked in the sheet; and    a second stage where a second punch and a second die in a paired relationship are used to blank the blanked body from the region in the sheet subjected to half-blanking in the first stage, and at such time, the second punch performs shaving work on at least a portion of a blanked surface along a blanking direction on a region where the blanked body is blanked.    
   
   
       19 . A press working method, which performs blanking work on a sheet, comprising: 
 a first stage where a first punch and a first die in a paired relationship are used to perform half-blanking work on a region where a blanked body is to be blanked in the sheet; and    a second stage where a second punch and a second die in a paired relationship are used to blank the blanked body from the region in the sheet subjected to half-blanking in the first stage, and at such time, the second die performs shaving work on at least a portion of a blanked surface along a blanking direction on the blanked body.