To enable ready removal and sure fixture with a small number of fixing pieces by constituting of uneven metal pieces arranged on the upper end side surface of a mold frame long side, and metal pieces for fixing them and pin bridges.

Uneven metal pieces 4 are fixed on the upper end side surface of a mold frame 13 long side in the form of its unevenness faced upward. The fixing pieces are formed of positions to be inserted into the recess portions of the uneven metal pieces 4 and inverted U-shape positions for holding pin bridges 10. The coupling parts with the insertion positions of the inverted U-shape positions are made into screw-fastening types by the use of a slot and screw, and rendered controllable in its positions. The pin bridges 10 having inserted pins 11 and fixed reinforcing bars 12 are positioned on the mold frame 13, and the insertion positions of the fixing metal pieces are inserted in recess portions lying spaces between the pin bridges 10 and the uneven metal pieces 4 before controlling the positions of the inverted U-shape positions and holding and fixing the pin bridges 10. The fixing metal pieces are prevented from falling off, and magnets are incorporated in the inner parts of the insertion positions. By this structure, movement of the pin bridges 10 can be easily prevented.