PURPOSE:To mass-produce a top-shaped valve from which a packing does not drop off, by protruding a vertical wall on the peripheral edge of the packing seat of a top-shaped body and using the tapered surface of a metal die to press the wall inward to form a recess and by injecting kneaded rubber into the recess to mold the packing. CONSTITUTION:A vertical wall 6 is protruded on the peripheral edge of the packing seat 5 of a top-shaped body 1. An upwardly tapered surface 8 is provided on the inside of a die 7 so that the tapered surface extends from the lower open end of the die. After the body 1 is set on a lower die 2, the wall 6 of the body 1 is pressed inward by the tapered surface 8 of the upper die 7 to form a recess of dovetail-shaped section. A piston 10 in a cylinder 9 is then moved down so that kneaded rubber 11 is injected under pressure through a passage 12 into the recess and an opening defined by the metal dies 2, 7 and is vulcanized. A packing 13 is thus molded in the recess and the opening. Since the press formation of the recess and the molding of the rubber are simultaneously effected, the number of processing steps is reduced. Because the wall 6 is inclined inward, a sufficient cross-sectional area is assured for a water passage.
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