Cooling fin and manufacturing method of the cooling fin

Abstract

A cooling fin includes fin parts integrally extending from a base part. Each fin part is partially formed at a slant so that a proximal end portion is straight and a distal end portion is wavy (corrugated). Each fin part is partially slanted to make each fin part wavier as coming closer to the distal end portion from the proximal end portion. In a manufacturing process of the cooling fin, firstly, a straight cooling fin is produced by extrusion molding (an extruding step). Subsequently, the distal end portion of each fin is partially bent in a direction intersecting an extruding direction into a wave shape (a bending step).

1 . A cooling fin comprising a plurality of fin parts arranged in a row and a base part integrally continuous to one ends of the fin parts to support the fin parts,
 wherein each fin part has a shape in which a proximal end portion continuous to the base part is straight and a distal end portion is wavy in a flow direction of a coolant which will flow through the fin parts.   
     
     
         2 . The cooling fin according to  claim 1 , wherein
 the distal end portion of each fin part has a wave shape designed to meet an expression (I):
     a≧f−w   (I) 
   
       where “f” is a pitch of the fin parts, “w” is a thickness of each fin part, and “a” is a height of the wave shape of each fin part. 
     
     
         3 . The cooling fin according to  claim 1 , wherein
 the distal end portion of each fin part has a wavy shape including a region oblique with respect to the coolant flow direction.   
     
     
         4 . A manufacturing method of a cooling fin comprising a plurality of fin parts arranged in a row and a base part integrally continuous to one ends of the fin parts to support the fin parts,
 the method comprising the steps of:   extruding a straight shaped fin including a plurality of fin parts each extending from the base part into a comb teeth shape; and   partially bending a distal end portion of each straight fin part in a direction intersecting an extruding direction to shape the distal end portion into a wave shape in a flow direction of a coolant which will flow through between the fin parts.   
     
     
         5 . The manufacturing method of the cooling fin according to  claim 4 , wherein
 the bending step includes arranging a jig in a clearance between the fin parts and bending the fin parts with the jig by cold working.   
     
     
         6 . The manufacturing method of the cooling fin according to  claim 5 , wherein the bending step includes placing the jig on one side and the other side of each fin part in a staggered pattern, and applying a load on the fin part by at least the jig placed on one side. 
     
     
         7 . The manufacturing method of the cooling fin according to  claim 4 , wherein
 he bending step includes placing the jig in a position corresponding to clearances between the fin parts having just been extruded, and bending the fin parts with the jig by hot working.   
     
     
         8 . The manufacturing method of the cooling fin according to  claim 7 , wherein
 the jig has comb teeth insertable in the clearances between the fin parts, and   the bending step further comprises moving the jig in the direction intersecting the extruding direction.   
     
     
         9 . The manufacturing method of the cooling fin according to  claim 4 , wherein
 the bending step further comprises forming the distal end portion of each fin part into the wavy shape including a region oblique with respect to the coolant flow direction.   
     
     
         10 . The cooling fin according to  claim 2 , wherein
 the distal end portion of each fin part has a wavy shape including a region oblique with respect to the coolant flow direction.   
     
     
         11 . The manufacturing method of the cooling fin according to  claim 5 , wherein
 the bending step further comprises forming the distal end portion of each fin part into the wavy shape including a region oblique with respect to the coolant flow direction.   
     
     
         12 . The manufacturing method of the cooling fin according to  claim 6 , wherein
 the bending step further comprises forming the distal end portion of each fin part into the wavy shape including a region oblique with respect to the coolant flow direction.   
     
     
         13 . The manufacturing method of the cooling fin according to  claim 7 , wherein
 the bending step further comprises forming the distal end portion of each fin part into the wavy shape including a region oblique with respect to the coolant flow direction.   
     
     
         14 . The manufacturing method of the cooling fin according to  claim 8 , wherein
 the bending step further comprises forming the distal end portion of each fin part into the wavy shape including a region oblique with respect to the coolant flow direction.