PURPOSE: To perform uniform heat-sealing between the entire surface of a flange part and a cover part by forcing the part inside of the caved-in part of a blank into the cavity of a die.
CONSTITUTION: The upper plunger 1 is lowered while the inner part of the lower cavity 3b is lowered by the upper plunger 1 and the lower plunger 2 pushing the inside central part 10a by the caved-in part 10d of the plastic blank 10. During the initial period of lowering, space and material are accumulated. When extrusion force is reduced to continue to lower the plungers, the quantity of material extending from the space between these plungers reduces, accordingly tension is applied to the material accumulated at the shell wall part 5'b' thereby said part continues to extend. At the completion of lowering, a space 12 is formed between the shell wall part 5'b and the inside 3b1 of the lower cavity. The shell wall part 5'b of substantially uniform wall thickness can be obtained by the control of extrusion force and lowering speed.
MIHASHI MINORU
KAWAGUCHI KIYOSHI
| JPS56135015A | 1981-10-22 | |||
| JPS5624110A | 1981-03-07 | |||
| JPS50126768A | 1975-10-06 | |||
| JPS5750325U | 1982-03-23 |