To attain repairing which requires only replacing a divided piece and metal mold cost reduction by forming a plurality of divided pieces formed with groove parts at their jointed parts, out of adjacent divided pieces jointed to each other and formed side by side.

This device is constituted of divided pieces 1, 2 which are made of metal such as cemented carbide and divided into a plurality of pieces, and a square type frame body 3 made of metal such as cemented carbide. The divided piece 1 involves a plurality of groove parts 1e, and inclined end surfaces 1f at both end parts of it. The divided piece 2 positioned between divided pieces 1 involves a plurality of grooved parts 2e formed vertically at a surface to be the joining part 2d of its both side parts, and inclined end surfaces 2f at both end parts of it. The divided pieces 1, 2 are fitted by being pressured in the square type frame body 3 in such a condition as their joining parts 1d, 2d and 2d, 2d are joined to each other and formed side by side, so that a lower metal mold K is formed. In this metal mold K, the groove parts 1e, 2e of adjacent divided pieces 1, 2 become in such a condition as to face each other, so as to form punch fitting holes.