Drill Bit And Hole Formation Method

Abstract

Provided are a hole formation method enabling the formation of a high-quality hole even when a workpiece material is a difficult-to-machining metal material or a fiber-reinforced composite material and a drill bit used in the method. A drill bit includes at least one cutting edge and a face (a leading flank and a trailing flank) positioned in the vicinity of the cutting edge, and on the face, a recess exhibiting a prescribed planar shape (groove) is provided. A hole formation method includes a hole formation step of machining a portion to be processed of a workpiece material by means of drilling to form a hole while a lubricant material for assisting machining process is in contact

1 . A drill bit used to form a hole by machining a portion to be processed of a workpiece material by means of drilling while a lubricant material for assisting machining process is in contact with the portion to be processed, the drill bit comprising:
 at least one cutting edge; and   a face positioned in a vicinity of the cutting edge,   wherein, on the face, a recess exhibiting a prescribed planar shape is provided;   when the portion to be processed is machined by means of drilling to form a hole, the lubricant material for assisting machining process is held on the recess;   the recess is set to have a maximum depth of 0.05 mm or more and 0.15 mm or less;   the recess is a substantially linear groove formed substantially parallel to the cutting edge;   a dimension between the cutting edge and the groove is set to be 0.25 mm or more and 0.43 mm or less; and   the groove is set to have an average width of 0.23 mm or more and 0.30 mm or less.   
     
     
         2 . The drill bit according to  claim 1 , wherein
 the face includes a leading flank adjacent to the cutting edge, and   the recess is provided on the leading flank.   
     
     
         3 . The drill bit according to  claim 1 , wherein
 the face includes a leading flank adjacent to the cutting edge and a trailing flank adjacent to the leading flank, and   the recess is provided on the trailing flank.   
     
     
         4 - 7 . (canceled) 
     
     
         8 . A hole formation method comprising:
 a hole formation step of machining a portion to be processed of a workpiece material by means of drilling to form a hole while a lubricant material for assisting machining process is in contact with at least one of a drill bit and the portion to be processed,   wherein, in the hole formation step, the drill bit according to  claim 1  is used.   
     
     
         9 . The hole formation method according to  claim 8 , wherein the lubricant material for assisting machining process has a sheet shape. 
     
     
         10 . The hole formation method according to  claim 8 , wherein
 the workpiece material has a thickness of 1.0 mm or more, and   a hole formed in the hole formation step has a diameter of 3.0 mm or more.   
     
     
         11 . The hole formation method according to  claim 8 , wherein the workpiece material is a difficult-to-machining metal material. 
     
     
         12 . The hole formation method according to  claim 8 , wherein the workpiece material is a fiber-reinforced composite material. 
     
     
         13 . The hole formation method according to  claim 8 , wherein the workpiece material is a material in which a difficult-to-machining metal material is in close contact with a fiber-reinforced composite material. 
     
     
         14 . The hole formation method according to  claim 11 , wherein the difficult-to-machining metal material is any one material selected from the group consisting of a titanium alloy, an aluminum alloy, a magnesium alloy, a low alloy steel, a stainless steel, and a heat-resistant alloy. 
     
     
         15 . The hole formation method according to  claim 11 , wherein the difficult-to-machining metal material is a Ti-6Al-4V titanium alloy. 
     
     
         16 . The hole formation method according to  claim 13 , wherein the difficult-to-machining metal material is any one material selected from the group consisting of a titanium alloy, an aluminum alloy, a magnesium alloy, a low alloy steel, a stainless steel, and a heat-resistant alloy. 
     
     
         17 . The hole formation method according to  claim 13 , wherein the difficult-to-machining metal material is a Ti-6Al-4V titanium alloy.