| 摘要 |
The present invention is directed to a forging method for forming a heat sink 9 including a base board 91 and a plurality of pin fins 92 integrally formed on an upper surface of the base board 91. A back pressure applying pin 75 of a forging die for forming pin fins 92 are slidably arranged in a fin-forming hole 52. At the time of plastically deforming a forging blank W, a back pressure is applied by the back pressure applying pin to a metal material of the forging blank W flowed into the fin-forming hole 52. A concave portion 76 is formed on the restraining tip end face of the back pressure applying pin 75 for restraining the metal material, and a joining convex portion 93 is integrally formed on a tip end of the pin fin 92 by the metal material filled in the concave portion 76. |
