Sankyo Kasei Kabushiki Kaisha

Niigata Engineering Co., Ltd.

Masakazu Ohno

Yukio Yoshizawa

Sumio Sato

Osamu Nakazawa

Masaki Ogawa

Motohiro Kobayashi

Shoji Miyajima

Chuzo Simizu

Toshio Inage

An improved injection molding apparatus having a fixed mold 7 having a molten resin passage 16b and a movable second mold 8 having a molten resin passage 18 is presented in which residual hardened resin left in molten resin passages of the injection apparatus is removed automatically after every injection operation. The invented device is provided with a reciprocating member 34 which is coupled in molten resin passages 16b, 18, and during the injection step, the molten resin passage 16b is extended to the molten resin passage 18 by moving the reciprocating member 34 into the second mold to communicate a mold cavity 17 with a resin injection device 14. After the completion of the injection step, the reciprocating member 34 is moved to the back position to remove any resin left in the molten resin passage towards the first mold. The mold is then opened to separate the fixed mold 7 from the movable mold 8, leaving the reciprocating member 34 in the first mold so as to close off the opening of the molten resin passage 18. When the molds 16b, 18 are separated, this arrangement is effective in preventing exposing the passages 16b, 18 to ambient atmosphere, leading to leaking of molten resin from the passage 16b as well as preventing inclusion of air in molded products to cause a phenomenon called burning.

Apparatus for forming synthetic resins

The present intention intends to operate an ejector which carries out gate cut and product ejection in an injection molding machine, at optimal speeds, respectively. According to the present invention, a control unit for controlling hydraulic or electric drive means for operating one or more than one ejector pin comprises operation speed setting means for gate cut and another operation speed setting means for product ejection. Such a structure enables to carry out gate cut by operating an ejector unit controlled by an ejector unit operation speed setting means for a gate cut and, subsequently, to carry out a product ejection from metallic molds by operating the ejector unit controlled by another ejector unit operation speed setting means for product ejection. The ejector unit is set at a comparatively high operation speed for gate cut so that no gate trace will remain, and at a comparatively low operation speed for product ejection so that no cracks will be generated in the product.

Gate-cut and ejection control apparatus and control method for an

To provide a resin molding method and apparatus that may realize a sprue runnerless system with a very simple structure and at a low cost, a molten resin 4 is fed from a resin supply portion 1 into a pair of cavities 3 through a resin passages 2 such as a sprue portion 2A and a pair of runner portion 2B for molding the resin. The method includes the following steps of: moving a resin return member 5 toward the resin supply portion 1 after supplying the molten resin 4 into the cavities 3, the resin return member 5 being disposed so as to be projectable into the resin passage 2 and movable through the resin passage 2; and returning a waste molded resin 6 under a molten/solid condition within the resin passage 2 back into the resin supply portion 1 under a molten condition by a heat of the resin supply portion 1.

Resin molding method and apparatus

Growing community of inventors

Tokyo, Japan

Masakazu Ohno