Patent ID: 7677430

Claim:
A cold-pressure welding method for producing a welded metal product, comprising: piling a plurality of metal plates different in hardness together; pressing the metal plates by a die in a direction intersecting surfaces of the metal plates; and cold-pressure welding and deforming the metal plates so as to form a recess portion, wherein one metal plate having a greater hardness of the metal plates different in hardness is disposed on a surface side of the metal plates toward which the die presses, wherein the hardness of each metal plate other than the one metal plate is at least the hardness of copper, the cold-pressure welding and deforming step comprising: restricting an extension of the metal plates in a width direction thereof by a lower mold and an upper mold so that widths of the metal plates match each other, and wherein the upper mold includes a groove so that the entire width of the one metal plate fits within the groove of the upper mold, and the lower mold includes a groove so that the entire width of the other metal plates fit within the groove of the lower mold, and wherein the die passes through the upper mold.