METHOD FOR FORMING FLANGED INTERMEDIATE CYLINDRICAL MEMBER HAVING ANNULAR STOPPER IN INNER DIAMETER

PURPOSE:To form the flanged cylindrical member having an annular stopper in the inner diameter by forming a T shape tubular intermediate member from a hollow circular blank and forming a flange part and outer cylindrical part with cold pressing by making the outer diameter dimension of the outer cylindrical part thereof as a reference. CONSTITUTION:A hollow circular blank 10 is obtd. by forming a plate stock, etc., of a mild iron stock. The inner diameter dphi, outer diameter Dphi and end face 10a of this blank 10 are constrained by a die and the circumference is subjected to cold pressing by the plunger punch of an inner diameter dimension Aphi. The intermediate member 11 having a flange part 11a and outer cylindrical part 11b is thus formed with holding the dimension of the circumference. The flange part 11a is spread in the outer diameter direction by compressing it with restraining the outer diameter of the outer cylindrical part 11b and the inner diameter of the flange part 11a of this intermediate member 11 and the flange part 12a in the necessary thickness is formed. The outer cylindrical part 11b is then expanded by backward extruding excepting the inner diameter part corresponding to the flange part 12a by using the stepped forming mandrel having the outer diameter part equal to said dphi and the outer diameter part larger than that and the outer cylindrical part 12b in the necessary thickness and the stopper 12c of the inner diameter part are formed. The flanged intermediate cylindrical member 12 having an annular stopper 12c on the inner diameter is thus obtd.