JPS641509A - Manufacture of plastic cap - Google Patents

Abstract

PURPOSE:To obtain a cap having excellent strength and quality, by a method wherein a skirt is formed of a material, which flows out to a space between the end of the side peripheral surface of a first plunger and the inner peripheral surface of a dice cavity, and the first and second plungers are introduced into the dice cavity. CONSTITUTION:A spiral recess 10, corresponding to the projected part of the screw of a cap 1, is formed on the lower end 5a of the side peripheral surface of an upper plunger 5 while the lower end surface 5b of the upper plunger 5 is provided with a configuration corresponding to the inner surface 2b of the ceiling plate 2 of the cap 1. A lower plunger 6 is provided with an upper end surface 6a, having a configuration corresponding to the outer surface 2c of the ceiling plate 2 of the cap 1, and a side peripheral surface 6b, having a configuration corresponding to the outer peripheral surface 3a of a skirt 3, and is constituted so as to be capable of sliding in the cavity 7a of a dice 7 having an inner peripheral surface 7a1 provided with a configuration corresponding to the outer peripheral surface 3a of the skirt 3. A pushing pad 8 is an annular body having an inner peripheral surface 8a capable of sliding along the side peripheral surface 5a of the upper plunger 5. Further, the pushing pad 8 is constituted so as to be capable of moving up-and-down by a driving mechanism with a predetermined timing through a vertical rod 11.