Mitsubishi Jukogyo Kabushiki Kaisha

Hideo Kuroda

Masayoshi Kasai

Yukio Tamura

Yoshio Shikase

Kouji Kubota

Sensho Saito

A process and apparatus for effecting injection molding of plastic resin products on an injection molding apparatus including a metal mold composed of a slidable mold element and a fixed mold element defining together the mold cavity, an actuator for sliding the slidable mold element and an injection nozzle for adjusting the nozzle flow path section, which comprises a first molding step of injecting a molten resin into the mold cavity which has been preset by the slidable mold element so as to include a post-compression margin to be compressed afterwards in a second molding step, to effect the injection under a reduced molding pressure, while causing a temperature elevation and, thus, a viscosity reduction of the molten resin, until the mold cavity has been filled up, and a second molding step of compressing the resin so charged in the mold cavity by operating the slidable mold element to compress the charged resin to compensate the post-compression margin, so as to allow an effective pressing force to be imposed onto the charged resin within the mold cavity also after the gate has been sealed.

Process for injection molding and apparatus therefor

The invention is embodied as a raw material resin feeding apparatus for a molding machine, such as an injection molding machine or an extruder. In this system, upon carrying out a variable resin-change operation by making use of material to be changed, raw material resin is intermittently fed to a feed section by intermittently opening and closing a resin passageway. The improvements reside in that the apparatus includes a raw resin material feed selection mechanism provided midway along a resin passageway for selectively either feeding a predetermined amount intermittently or continuously to a feed section. A resin-change resin feed start detector mechanism is provided for detecting completion of discharge of the amount of raw material corresponding to the predetermined amount, and a resin-change completion detector mechanism is provided. With this apparatus, raw material can be selectively fed to effect quick resin-change or for normal operation.

Growing community of inventors

Nagoya, Japan

Hideo Kuroda