Drilling method, resist layer, and fiber-reinforced plastic

Abstract

In an embodiment, provided is a drilling method of Bawling a hole having a desired diameter in a fiber-reinforced plastic workpiece. The method includes disposing a resist layer, in which an opening having a diameter smaller than the desired diameter is formed, on the workpiece and ejecting blasting abrasives to the workpiece through the resist layer to cut a portion, which is exposed from the opening, in the workpiece while cutting a peripheral edge portion of the opening of the resist layer.

1 . A drilling method of forming a hole having a desired diameter in a fiber-reinforced plastic workpiece, comprising steps of:
 disposing a resist layer, in which an opening having a diameter smaller than the desired diameter is formed, on the workpiece; and   ejecting blasting abrasives to the workpiece through the resist layer to cut a portion, which is exposed from the opening, in the workpiece while cutting a peripheral edge portion of the opening of the resist layer.   
     
     
         2 . The drilling method according to  claim 1 ,
 wherein a ratio of the diameter of the opening to the desired diameter is 0.84 or more and 0.94 or less.   
     
     
         3 . The drilling method according to  claim 1 ,
 wherein in the step of ejecting the blasting abrasives to the workpiece, the blasting abrasives are ejected toward the workpiece from a nozzle, and   an angle formed by a surface of the workpiece and a ejecting direction of the blasting abrasives from the nozzle is 90°±5°.   
     
     
         4 . The drilling method according to  claim 3 ,
 wherein the nozzle is configured to suck the blasting abrasives by introducing compressed air to the inside of the nozzle to eject the blasting abrasives with the compressed air as a solid-gas two-phase flow.   
     
     
         5 . The drilling method according to  claim 1 ,
 wherein the workpiece comprises the fiber-reinforced plastic in which a cut reinforcing fibers are dispersed in a resin.   
     
     
         6 . The drilling method according to  claim 1 ,
 wherein the workpiece comprises the fiber-reinforced plastic in which a woven reinforcing fibers infiltrate into a resin.   
     
     
         7 . A resist layer that is used in the drilling method according to  claim 1 ,
 wherein the resist layer is a polymer including unsaturated polyurethane or an abrasion-resistant rubber as a main component.   
     
     
         8 . A fiber-reinforced plastic having a hole formed by the drilling method according to  claim 1 ,
 wherein the fiber-reinforced plastic has a plate shape having a thickness of 1.0 mm or more and 2.0 mm or less, and   an angle formed by a plane perpendicular to a central axis line of the hole and a wall surface defining the hole is 80° or more and 90° or less.   
     
     
         9 . A drilling method of forming a hole in a fiber-reinforced plastic workpiece having a front surface and a rear surface, the hole being opened on the front surface and the rear surface and having a first opening on the front surface side having a first area, comprising:
 disposing a resist layer having blast resistance higher than blast resistance of the workpiece on the workpiece, the resist layer having a second opening which has a shape corresponding to a shape of the first opening and has a second area smaller than the first area; and   ejecting blasting abrasives to the workpiece through the resist layer to cut a portion, which is exposed from the second opening, in the workpiece while cutting a peripheral edge portion of the second opening of the resist layer.