Extrusion die for metallic material

Abstract

In some preferred embodiments, an extrusion die 10 for a metallic material includes a die case 20 having a pressure receiving portion 21 with a metallic material pressure receiving surface 22 faced rearward against an extrusion direction, a male die 30 disposed in the die case 20 , and a female die 40 disposed in the die case 20 . The pressure receiving portion 21 is formed into a convex configuration protruded rearward, and a porthole 24 for introducing the metallic material is provided in an outer periphery of the pressure receiving portion 21 . A ratio of a flat state opening area Sb of a porthole inlet portion 24 e to a flat state area Sa of the pressure receiving portion 21 is set to 0.15 to 0.80. The extrusion die is configured such that the metallic material pressurized against the metallic material pressure receiving surface 22 is introduced into the die case 20 via the porthole 24 and passes through the extrusion hole 11.

1 . An extrusion die for a metallic material, comprising:
 a die case having a pressure receiving portion with an outer surface functioning as a metallic material pressure receiving surface, the die case being disposed with the metallic material pressure receiving surface faced rearward against an extrusion direction of the metallic material;   a male die disposed in the die case; and   a female die disposed in the die case to define an extrusion hole between the male die and the female die,   wherein the pressure receiving surface is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is provided in an outer periphery of the pressure receiving portion,   wherein a ratio of an opening area of an inlet portion of the porthole defined by a plan view as seen from an axial upstream side (a plan state opening area of the inlet portion of the porthole) to an area of the pressure receiving portion defined by a plan view as seen from the axial upstream side (a plan state area of the pressure receiving portion) is set to 0.15 to 0.80, and   wherein the extrusion die is configured such that the metallic material pressurized against the metallic material pressure receiving surface is introduced in the die case via the porthole and passes through the extrusion hole.   
   
   
       2 . The extrusion die for a metallic material as recited in  claim 1 , wherein the porthole is configured such that the opening area of the inlet portion is larger than a passage cross-sectional area of an inside of the porthole. 
   
   
       3 . The extrusion die for a metallic material as recited in  claim 1 , wherein the porthole is configured such that a passage cross-sectional area gradually decreases from the inlet portion toward an inside of the porthole. 
   
   
       4 . The extrusion die for a metallic material as recited in  claim 1 , wherein the porthole is configured such that a radial length (thickness)) of the inlet portion is set to be larger than a thickness of an inside of the porthole. 
   
   
       5 . The extrusion die for a metallic material as recited in  claim 1 , wherein the porthole is configured such that a circumferential length (width) of the inlet portion is set to be larger than a width of an inside of the porthole. 
   
   
       6 . The extrusion die for a metallic material as recited in  claim 1 , wherein the metallic material pressure receiving portion is constituted by a convex spherical surface of a ⅙ to 4/6 sphere. 
   
   
       7 . The extrusion die for a metallic material as recited in  claim 1 , wherein a plurality of portholes are formed at regular intervals in a circumferential direction about an axis of the die case. 
   
   
       8 . The extrusion die for a metallic material as recited in  claim 1 , wherein the porthole is arranged toward the extrusion hole. 
   
   
       9 . The extrusion die for a metallic material as recited in  claim 1 , wherein an inclination of an axis of the porthole with respect to an axis of the die case is set to 3 to 45°. 
   
   
       10 . The extrusion die for a metallic material as recited in  claim 1 ,
 wherein the extrusion hole is formed into a flat cross-sectional configuration with a width larger than a thickness, and   wherein the portholes are formed at positions corresponding to thickness directional both sides of the extrusion die.   
   
   
       11 . The extrusion die for a metallic material as recited in  claim 1 ,
 wherein the male die and the female die define a flat circular extrusion hole with a height (thickness) smaller than a width,   wherein a portion of the male die corresponding to the extrusion hole is formed into a comb-like configuration having a plurality of passage forming protrusions arranged in a width direction, and   wherein the extrusion die is configured such that the metallic material passes through the extrusion hole to form a multi-passage hollow member with a plurality of passages arranged in a width direction.   
   
   
       12 . The extrusion die for a metallic material as recited in  claim 1 , wherein the male die and the female die define a circular extrusion hole, and the extrusion die is configured such that the metallic material passes through the extrusion hole to form a tubular member circular in cross-section. 
   
   
       13 . A die case for an extrusion die, comprising a pressure receiving portion with an outer surface functioning as a metallic material pressure receiving surface faced rearward against an extrusion direction of the metallic material, the die case being configured to mount a male die and a female die therein,
 wherein the pressure receiving surface is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is provided in an outer periphery of the pressure receiving portion,   wherein a ratio of an opening area of an inlet portion of the porthole defined by a plan view as seen from an axial upstream side (a plan state opening area of the inlet portion of the porthole) to an area of the pressure receiving portion defined by a plan view as seen from the axial upstream side (a plan state area of the pressure receiving portion) is set to 0.15 to 0.80, and   wherein the die case is configured such that the metallic material pressurized against the metallic material pressure receiving surface is introduced into the die case via the porthole and passes through the extrusion hole.   
   
   
       14 . The die case for an extrusion die as recited in  claim 13 , wherein the metallic material pressure receiving portion is constituted by a convex spherical surface of a ⅙ to 4/6 sphere. 
   
   
       15 . An extrusion method for a metallic material, comprising the steps of:
 preparing a die case, wherein the die case comprises a pressure receiving portion with an outer surface functioning as a metallic material pressure receiving surface faced rearward against an extrusion direction of the metallic material, a male die mounted in the die case, and a female die mounted in the die case for defining an extrusion hole between the male die and the female die, wherein the pressure receiving surface is formed into a convex configuration protruded rearward, and a porthole for introducing the metallic material is provided in an outer periphery of the pressure receiving portion, and wherein a ratio of an opening area of an inlet portion of the porthole defined by a plan view as seen from an axial upstream side (a plan state opening area of the inlet portion of the porthole) to an area of the pressure receiving portion defined by a plan view as seen from the axial upstream side (a plan state area of the pressure receiving portion) is set to 0.15 to 0.80; and   introducing the metallic material pressurized against the metallic material pressure receiving surface into the die case via the porthole to pass through the extrusion hole.