| 摘要 |
PURPOSE:To enable the weld line occurring at the boss part of a molding to be perfectly removed by pushing out a punch into the molten resin in a cavity before the solidification of the molten resin. CONSTITUTION:A cavity 8 is filled with a molten resin 52 injected by way of a sprue member 20. Before the solidification of the molten resin, a punch 46 and a slide pin 36 are moved in the left direction. While the punch 46 is inserted into the molten resin 52 by said movement, the molten resin 52 is pushed out by the volume corresponding to the movement of the slide pin 36, whereby a boss part is molded. On the other hand, at the portion where the punch 46 is inserted, a hole is molded in the boss part. The moving speed of the slide pin 36 is made slower than that of the punch 46. At the time point where a boss part with desired height is provided, the tip surface of the punch 46 is in contact with the tip surface of the slide pin 36. Accordingly, no weld line is generated at the periphery of the boss.
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