Plunger tip for die casting and injection device

Abstract

A plunger tip for die casting is configured to slide in a cylindrical sleeve to inject a molten metal in the cylindrical sleeve into a mold and includes a crushing portion and recesses. The crushing portion is provided on an outer peripheral surface on a front end side of the plunger tip and is capable of contacting a solidified layer of the molten metal generated on an inner peripheral surface of the cylindrical sleeve to crush the solidified layer. The recesses are provided on both sides of the crushing portion in a circumferential direction and recessed radially inward from the crushing portion. The crushing portion has a triangular shape and is a region between two of the recesses adjacent to each other in the circumferential direction and in which a front end side of the plunger tip is an apex.

1 . A plunger tip for die casting, the plunger tip being configured to slide in a cylindrical sleeve to inject a molten metal in the cylindrical sleeve into a mold, the plunger tip comprising:
 a crushing portion that is provided on an outer peripheral surface on a front end side of the plunger tip and is capable of contacting a solidified layer of the molten metal generated on an inner peripheral surface of the cylindrical sleeve to crush the solidified layer; and   recesses provided on both sides of the crushing portion in a circumferential direction and recessed radially inward from the crushing portion, wherein   the crushing portion has a triangular shape and is a region between two of the recesses adjacent to each other in the circumferential direction and in which a front end side of the plunger tip is an apex.   
     
     
         2 . The plunger tip according to  claim 1 , wherein
 the plunger tip comprises crushing portions comprising the crushing portion,   the crushing portions and the recesses are provided on an entire circumference of the plunger tip such that the crushing portions and the recesses are alternately arranged in the circumferential direction.   
     
     
         3 . The plunger tip according to  claim 1 , wherein an outer diameter of the plunger tip gradually decreases toward a front end side of the plunger tip in a region where the crushing portions is provided. 
     
     
         4 . The plunger tip according to  claim 2 , wherein an outer diameter of the plunger tip gradually decreases toward a front end side of the plunger tip in a region where the crushing portions is provided. 
     
     
         5 . The plunger tip according to  claim 1 , wherein a bottom surface of each of the recesses is inclined inward in a radial direction of the plunger tip toward a front end side of the plunger tip. 
     
     
         6 . The plunger tip according to  claim 2 , wherein a bottom surface of each of the recesses is inclined inward in a radial direction of the plunger tip toward a front end side of the plunger tip. 
     
     
         7 . The plunger tip according to  claim 1 , further comprising:
 a rear crushing portion provided on an outer peripheral surface of a rear end portion of the plunger tip and capable of contacting the solidified layer generated on an inner peripheral surface of the cylindrical sleeve to crush the solidified layer; and   rear recesses provided on both sides of the rear crushing portion in the circumferential direction and recessed radially inward from the rear crushing portion, wherein   the rear crushing portion has a triangular shape in which a rear end side of the plunger tip is an apex in a region between two of the rear recesses adjacent in the circumferential direction.   
     
     
         8 . The plunger tip according to  claim 2 , further comprising:
 a rear crushing portion provided on an outer peripheral surface of a rear end portion of the plunger tip and capable of contacting the solidified layer generated on an inner peripheral surface of the cylindrical sleeve to crush the solidified layer; and   rear recesses provided on both sides of the rear crushing portion in the circumferential direction and recessed radially inward from the rear crushing portion, wherein   the rear crushing portion has a triangular shape in which a rear end side of the plunger tip is an apex in a region between two of the rear recesses adjacent in the circumferential direction.   
     
     
         9 . An injection device for die casting, the injection device comprising:
 a cylindrical sleeve; and   a plunger tip configured to slide in the cylindrical sleeve to inject a molten metal in the cylindrical sleeve into a mold, wherein   the plunger tip comprises:   a crushing portion that is provided on an outer peripheral surface on a front end side and is capable of contacting a solidified layer of the molten metal generated on an inner peripheral surface of the cylindrical sleeve to crush the solidified layer; and   recesses provided on both sides of the crushing portion in a circumferential direction and recessed radially inward from the crushing portion, and   the crushing portion has a triangular shape and is a region between two of the recesses adjacent to each other in the circumferential direction and in which a front end side of the plunger tip is an apex.