| 摘要 |
A method and apparatus for making high speed injection molded ultra-thin walled plastic parts which are scarless at the gate area so that molten mold material fills a hot runner system 2, and is kept under pressure. The mold material fills the channel 4 and the recessed area 9. A core pin is initially kept at a position such that the central cylindrical body portion 8b of the core pin 8 seals off, or blocks,the mold cavity 10 at the annular gate 9a. To fill the mold cavity 10, hydraulic pressure is applied to the proximal end of the core pin, and the core pin 8 is depressed a predetermined distance. The pin 8 is held in the depressed position such that the tapered end portion 8c is positioned to open the gate 9a and allow molten molding material to flow under pressure into the molding cavity 10. At predetermined time sufficient for the mold cavity 10 to be filled with molten mold material, the hydraulic pressure on the core pin 8 is switched, and the core pin 8 returns to a predetermined position within the channel 4, such that the central cylindrical body portion 8b of the core pin 8 is in contact with and seals off the annular gate 9a. In this way, the core pin 8 creates a scarless opening 9b at the gate 9a. The mold half blocks 15 and 16 are then separated by any mechanical means to reveal the molded part 17 which is preferably retained in either mold half block. The part is then mechanically and preferably automatically removed from the mold. <IMAGE> |
