PURPOSE: To perform easily punching by machining with less man-hour and excellent working accuracy in the stage of manufacturing parts for hydraulic control apparatus having many fluid passages by dividing beforehand blank materials for the parts so as to facilitate punching and assembling the materials after punching.
CONSTITUTION: Two pieces of half split metallic blank materials 10 are prepared and half split surfaces 11 are finished to good dimensional accuracy. A spool hole 12 is ground from the surface 11 side and an Ni coating layer 14 having 0.1μ thickness is formed on the non-ground surface 13 by a vacuum deposition method. The two blank materials worked in the above-mentioned way are correctly mated with the worked surfaces, and thereafter the coating parts 14 are welded by a diffusion welding method. A pressure transmission hole 2 is finally worked in a prescribed position and a desired part for a hydraulic control apparatus is completed.
KADOI JIYUN
ITANO SHIGEO
WADA TETSUYOSHI
OHARA KATSUTOSHI
