| 摘要 |
A core assembly is provided to improve durability of a core by reducing wear of a front end of a molding protrusion to improve productivity of injection-molding. A core assembly includes a first core(31) and a second core(51). A plurality of molding protrusions(33) are projected on a surface of the first core. The second core has a cavity formed by being coupled to the first core and air holes(57,57') on a surface on which the cavity is formed. A part of front ends of the molding protrusions is inserted into the air holes. The second core further includes cavity forming units(55,55') indented at a predetermined depth on a surface facing the molding protrusions. The air holes communicate an inside of the cavity with an outside through the cavity forming units.
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