Method for producing water jacket spacer

Abstract

A spacer ( 1 ) is injection molded by using an injection molding die having resin flow channels that are designed such that a plurality of gates ( 6 ) are arranged along the longitudinal direction at a position corresponding to the outer peripheral surface of a side wall part ( 4 ) in which a plurality of arc-like peripheral surface parts ( 2 ) are connected through a waist part ( 3 ). After opening the mold and ejecting the spacer, the spacer is cooled with a runner ( 7 ) being connected to the gate ( 6 ), and thereafter, the runner ( 7 ) is cut off. As a result, when producing a water jacket spacer that is assembled to the inside of the water jacket and controls the flow of cooling water by injection molding, while producing with a high productivity without being affected by design constraints caused by draft angle, deformation in the post-molding cooling step is prevented.

1 . A method for producing a water jacket spacer that is assembled into the inside of a water jacket provided in a water-cooled internal combustion engine in order to control the flow of cooling water, wherein
 the water jacket spacer has a shape having a side wall part in which a plurality of arc-like peripheral surface parts are connected through a waist part;   a prescribed resin material is injection molded by using a molding die for injection molding in which resin flow channels are designed so that a plurality of gates are arranged along the longitudinal direction at a position corresponding to both ends in the direction orthogonal to the longitudinal direction of the water jacket spacer, but any gates are not arranged at a position corresponding to an inner peripheral surface of the side wall part being a surface facing a bore wall of the water-cooled internal combustion engine when the water jacket spacer is assembled into the inside of a water jacket,   whereby there is no need to provide draft angle on the inner peripheral surface of the side wall part and it is possible to be opposed to the bore wall along an inclination thereof when the water jacket spacer is assembled into the inside of the water jacket,   after mold opening and ejecting, cooling is done while leaving a runner being connected to the gates in a shape of a teeth of a comb, and thereafter, the runner is cut off.