| 摘要 |
PURPOSE:To prevent the deformation of a molded bellows caused by a pulling action of one mold by providing a reinforcing pin that acts to prevent the deformation of molding during mold releasing period in the vicinity of the outer periphery of a mold cavity in the case of injection-molding bellows or the like for controlling the ink flux quantity of a writing utensil. CONSTITUTION:On the cavity parts of split-molds 1A, 1B, a number of partition plates 2A, 2B are projectingly provided in parallel at predetermined intervals and semicircular holes 3a, 3b are formed on the central parts of tapered surfaces and reinforcing pin fitting notched holes 6a, 6b are formed in the bellows outer peripheral part at both sides thereof. The molds 1A, 1B are closed and, in the formed central hole 3 and reinforcing pin fitting hole 6, a core pin 4 and rectangular rod-shaped reinforcing pin 7 are inserted respectively. Then, resin is injected from pouring gates 8A, 8B for forming bellows 5. When the molds 1A, 1B are opened, the molded bellows 5 is obstructed in its movement by the core pin 4 and reinforcing pin 7 and thereby the bellows 5 are not deformed by the pulling action of one mold even in the case where the partition plates 2A, 2B and bellows 5 are different in their chamfers. |
