| 摘要 |
PROBLEM TO BE SOLVED: To reduce the amount of burrs that are generated frequently by extending a rotation prevention groove on the opposite side surface of the cavity formation surface of a drag cavity block toward the center of a cavity. SOLUTION: A cavity 11 that is a square recessed part is formed on the upper surface of a drag cavity block 10, a force-cutting surface 11a is formed around the cavity 11, at the same time a round gate pin 12 being inserted into a through hole 10a is formed at one corner of the cavity 11. Then, a rotation prevention groove 13 is provided so that it is engaged to the collar part of the round gate pin 12 and is extended and formed up to the center of the cavity 11 including the through hole 10a from the outside of the cavity 11 formed on the upper surfaced of the drag cavity block 10, thus preventing the decrease in the applied pressure to be applied to a force-cutting surface 11a in molding and preventing burr from occurring.
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