| 摘要 |
The present invention provides a manufacturing method for manufacturing an outer tube of an injector having a barrel portion having an excellent circularity, while preventing generation of distortion or warp. A molten resin is injected into a cavity 17 of a metal mold 11 including: a fixed mold 13 having a hole portion 12 having a shape along the outer shape of the injector outer tube 1 ; a movable mold 14 closing the hole portion 12 ; and a core 15 inserted into the hole portion 12 . A cylindrical vacant portion is provided communicating with a flange forming portion 20 of the hole portion 12 . The molten resin R is injected from a sprue 22 and a runner 23 via a submarine gate 24 into the cylindrical vacant portion 21 and the molten resin R is introduced into the cavity 17 . The cylindrical vacant portion 21 has a push pin 25 . When the molten resin has become half-molten state, the resin in the cylindrical vacant portion is introduced with pressure into the cavity 17 by the push pin 25 . When the amount of the molten resin R in the cavity 17 is insufficient, a wait position of the push pin is moved in a direction apart from the connection portion of the submarine gate 24 , so as to inject the molten resin R and supplement the insufficient resin in the cavity 17.
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