PURPOSE: To manufacture a bimetallic cylinder having high accurate inner diameter surface by forming firm oxide film on a core of material having large coefficient of thermal expansion, inserting this core into a hole in cylinder base material and taking out the core after executing hot isostatic pressing treatment and cooling.
CONSTITUTION: The core 11 obtd. by joining one pair of a first and second cores 11a, 11b at right and left sides, is inserted into the hole 12a in the cylinder 12, thus space 13 for packing metal powder is formed between the core 11 and the hole 12a. The material of this core 11 has the coefficient of thermal expansion larger than the coefficient of thermal expansion of the material of cylinder 12, and on this surface, chemical treatment of black oxide film treatment, etc., is applied to form the firm oxide film. Into the above space 13 for packing metal powder, e.g. Ni-base corrosion resistant and wear resistant alloy powder is packed and the hot isostatic pressing is applied. By this method, lining layer 14 is formed. In cooling process after that, the core 11 and the lining layer 14 are easily separated with the difference of the coefficient of thermal expansion between the core 11 and the cylinder 12. Successively, the core 11 is taken out from the cylinder by extruding and the high accurate lining layer is fitted and formed in the inner face of cylinder 12.
SUGIYAMA YUTAKA
KATSUNO HARUO
TANAKA KAZUYUKI
