| 摘要 |
PROBLEM TO BE SOLVED: To provide a plunger of a resin molding device which is capable of smoothly moving up/down and extending the life of a pot. SOLUTION: The plunger 3 mounted in the pot 2 has axial grooves 4 formed from the edge face to a specified position in the axial direction (a direction parallel with the edge face) on the side and a peripheral groove 5 formed across the entire periphery of the side of the plunger 3. Thus when the plunger 3 presses a molten resin 7, the molten resin 7 is forcibly injected into the peripheral groove 5 through each of the axial grooves 4 to form a seal ring 10. Consequently, the penetration of the molten resin 7 into a gap between the pot 2 and the plunger 3 is inhibited, resulting in the decrease of a sliding resistance between the pot 2 and the plunger 3 and in turn, the smooth ascending/ descending motion of the plunger 3. After all, the wear of the inner face of the pot 2 is suppressed and the life of the pot 2 is extended.
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