| 摘要 |
PROBLEM TO BE SOLVED: To be excellent in dimensional stability in mass production, to surely stand stress in a weld line, and to prevent breakage in a synthetic resin piston. SOLUTION: In the synthetic resin piston 1, oil pathways 3 are formed at approximately equal intervals in six places along a projection, and a gate 5 is formed between the oil pathways 3 of two places to form one weld line 6 between the oil pathways 3 of opposite two places. In the synthetic resin piston 1, since the oil pathway 3 is formed by denting a part of the projection 2, the cross-sectional area 3A of oil pathway 3 parts is smaller than the cross-sectional area 2A of a projection 2 part. By forming the weld line 6 in the projection 2 part of a larger cross-sectional area while avoiding the oil pathway 3 parts of a smaller cross-sectional area, the weld line 6 causing the decrease of strength is surely prevented from being formed in the oil pathway 3 parts, so that the synthetic resin piston 1 high in reliability can be formed. COPYRIGHT: (C)2006,JPO&NCIPI |
