Method for controlling an ejector and injection molding machine

摘要

A method for ejecting a molded product from a die. The method includes advancing an ejector pin from a withdrawn position to a projected position for ejecting a molded product and withdrawing the ejector pin from the projected position to the withdrawn position. At a preset range in at least one of the advancing step and the withdrawing step, the ejector pin undergoes very small reciprocating movements having a period less than 0.1 seconds. When the ejector pin is advanced while very small reciprocation is performed over a preset range in the advancing step, energy due to the projection of the ejector pin is continuously and gradually dissipated. When the ejector pin is withdrawn while very small reciprocation is performed over a preset range in the withdrawing step, the molded product is easily separated from the ejector pin. Accordingly, scattering of molded products and generation of cracks in the molded products can be prevented. Also, the molded product is prevented from being placed back into the cavity. Further, a dwell step may be provided in which the ejector pin is maintained at its projected position while being subjected to very small reciprocation having a period shorter than 0.1 seconds.