| 摘要 |
PURPOSE:To prevent the intrusion of a solidified metal into a cavity and to improve quality by advancing a small-diameter inner plunger tip in the mid-way of injection to allow the solidified metal to remain in the space part formed in the vertical hole in the lower part of a die. CONSTITUTION:The molten metal existing along the inside wall surface of a casting sleeve 32 solidifies partly to generate a shell 39 in said sleeve. The shell 39 is forced upward by the outer plunger tip 33 as the plunger 27 ascends, until the shall contacts with a contact surface 18 by which the shell is compressed. The inner plunger 34 ascends and projects from the top end face of the tip 33 when a pressure oil is fed into the oil chamber in the plunger 27. The compressed shell 39 is captured by the space part 19a between an inner plunger tip 35 and the inside circumferential surface of a stationary sleeve 19. The shell 39 remains consequently in the space part 19a without intruding into the cavity 15. |
