| 摘要 |
PROBLEM TO BE SOLVED: To satisfactorily exclude the thermal decomposition and carbonation of a resin at both ends of a resin passage by closing both width ends of upper and lower mold pieces parallel to each other by side pieces and forming the inner surface of each of the side pieces into a groove surface of a recessed curved surface or a groove surface of an outside angle corner and reducing the groove depth of the groove surfaces of the side piece parts in the vicinity of a resin emitting orifice. SOLUTION: Both ends of a resin passage formed by the connection of the resin passage 24 between upper and lower mold pieces 21, 22, the passage 16 just under a choke bar and a manifold part 13 are closed by side pieces 23, 23. The surfaces facing to the resin passage 24 between the upper and lower mold pieces 21, 22 of the side pieces are formed into circular arc groove surfaces 25 and the quantity of heat received by a resin is reduced and contact friction resistance is reduced. Further, the groove depth of the groove surface 251 of the parts of the side pieces 23 in the vicinity of the emitting orifice of the resin passage is reduced. The change of the cross-sectional area of the resin passage between the upper and lower mold pieces by providing grooves to the side pieces 23 is fine and, when the groove depth of short side piece parts is reduced, the flow velocity only of the resin at the part coming into contact with a groove surface can be increased. |
