Plunger tip and sliding method

Abstract

A plunger tip slides along an inner surface of the plunger sleeve and that injects a molten metal into a mold. The plunger tip includes: a tip main body; a ring-shaped hard resin member that is attached to an outer peripheral surface of the tip main body and that is in contact with the inner surface of the plunger sleeve at least during a hot period in which the plunger tip slides along the inner surface of the plunger sleeve; and a silicone resin member positioned between the tip main body and the ring-shaped hard resin member, in which a radial thickness of the silicone resin member during the hot period is thinner than a radial thickness of the silicone resin member during a cold period in which the molten metal is not supplied in the plunger sleeve.

What is claimed is: 
     
         1 . A plunger tip that slides along an inner surface of a plunger sleeve and that injects a molten metal into a mold, the plunger tip comprising:
 a tip main body;   a ring-shaped hard resin member that is attached to an outer peripheral surface of the tip main body and that is in contact with the inner surface of the plunger sleeve at least during a hot period in which the plunger tip slides along the inner surface of the plunger sleeve; and   
       a ring-shaped elastic member positioned between the tip main body and the ring-shaped hard resin member, wherein
 a radial thickness of the ring-shaped elastic member during the hot period is thinner than a radial thickness of the ring-shaped elastic member during a cold period in which the molten metal is not supplied in the plunger sleeve. 
 
     
     
         2 . The plunger tip according to  claim 1 , wherein the ring-shaped elastic member is formed of a silicone resin. 
     
     
         3 . The plunger tip according to  claim 1 , wherein the ring-shaped elastic member is an elastic spring. 
     
     
         4 . The plunger tip according to  claim 1 , wherein the ring-shaped hard resin member is in contact with the inner surface of the plunger sleeve both during the hot period and during the cold period. 
     
     
         5 . A sliding method in which a plunger tip is slid along an inner surface of a plunger sleeve to inject molten metal into a mold, the plunger tip comprising:
 a tip main body;   a ring-shaped hard resin member that is attached to an outer peripheral surface of the tip main body and that is in contact with the inner surface of the plunger sleeve at least during a hot period in which the plunger tip slides along the inner surface of the plunger sleeve; and   a ring-shaped elastic member positioned between the tip main body and the ring-shaped hard resin member, wherein   a radial thickness of the ring-shaped elastic member during the hot period is thinner than a radial thickness of the ring-shaped elastic member during a cold period in which the molten metal is not supplied in the plunger sleeve.   
     
     
         6 . The sliding method according to  claim 5 , wherein the ring-shaped elastic member is formed of a silicone resin. 
     
     
         7 . The sliding method according to  claim 5 , wherein the ring-shaped elastic member is an elastic spring. 
     
     
         8 . The sliding method according to  claim 5 , wherein the ring-shaped hard resin member is in contact with the inner surface of the plunger sleeve both during the hot period and during the cold period.