PURPOSE: To carry out the highly accurate machining of the outside diameter dimension and straightness of a pipe having an aperture on the peripheral wall by forming a groove hole along the inner wall face of the aperture to be formed on the peripheral wall of pipe while leaving the peripheral wall in part and, after carrying out the finishing polishing of the outside diameter face, cutting the remaining portion.
CONSTITUTION: After roughly machining the outside diameter face of a pipe 10 to be machined having no hole, a groove hole 12 is opened along the inner wall face 11 of an aperture to be formed on the peripheral wall 10a of the pipe 10 while leaving the peripheral wall in part. Thereby, a part 13 of the peripheral wall of the pipe 10 remains inside the aperture to be formed with its peripheral wall edge being in close vicinity to the inner wall face 11 while, at the same time, the part 13 is left linked to the peripheral wall 10a with the bridging portions 14 which are left uncut. Also, due to the perforating machining, the peripheral wall in the vicinity of the groove hole 12 is deformed by a residual stress. Then, the outside diameter face of the pipe 10 is subjected to close finishing polishing. In this case, since the part 13 of the peripheral wall remains on the aperture portion, the polishing stone is guided and slides on the outside diameter face of the part 13 of the peripheral wall passing on the inner wall face 11 in the advancing direction. Hence, no chipping off of the abrasive grains out of the polishing stone due to an edge portion occurs while removing the deformed projecting portion caused by the residual stress by means of polishing, forming a complete aperture 15.
IMURA YOSHIAKI
MATSUURA SHINJI
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