Abstract: A failsafe device, or pressure relief mechanism, for a shooting pot actuator in an injection molding machine. The shooting pot actuator has a multiple pusher rods mounted on one, or more, plates. Moving the plate holding the pusher rods depresses the shooting pot injection pistons and injects molten material into a number of mold cavities. To avoid damage to the machine from the pusher rods if an injection piston seizes, a failsafe device is used to mount the pusher rods to the plates. A shearing member is interposed, or sandwiched, between first and second apertures. Typically, the shearing member is a plate that, in normal operating conditions, blocks rearward movement of the pusher rod. However, when a predetermined shear force is applied to the shear plate, the shearing member shears and the pusher rod retracts within the channel, thereby alleviating the pressure.

Abstract: An injection molding machine, and stack assembly, employing a novel mold gate insert that can decrease the cycle time of the machine, and crystallinity and other defects in the mold gate area of plastic articles. A mold gate insert is described that is formed in two pieces. A first portion of the insert can forms a gate land for valve gated machines, and can thermally shield the nozzle tip. This first portion is made of a wear resistant material having a relatively low thermal conductivity, such as H13 tool steel. A second portion of the insert forms a section of the mold cavity and is made of a relatively highly thermally conductive material, such as beryllium copper. During the cooling phase of the injection cycle, the second portion provides rapid dissipation of heat to cool the section of the mold cavity, while the first portion creates a thermal barrier to shield the nozzle tip from the cooling of the second portion.

Abstract: A valve stem is mounted in a nozzle body, with the valve stem moving from an open position retracted from the injection orifice permitting the flow of resin to the mold cavity, to a closed position blocking the injection orifice and preventing the flow of resin to the mold cavity, and to an advanced position within the gate nub area to assist in the ejection of a molded part and clear the gate nub area.

Abstract: A plastic article is formed in an injection mold by injecting molten plastic into the injection mold at an elevated temperature, cooling the plastic from the molten condition to a solid condition, and crystallizing a portion of the plastic by slowing down the cooling of said portion.

Abstract: A shooting pot actuator for an injection molding machine having two plates carrying pusher rods for pushing against injection plungers within the shooting pots. The plates are mounted outside the mold and the clamp unit, and the pushers extend through bores in the stationary platen of the clamp unit to reach the injection plungers.

Abstract: A sprue bar assembly for a melt transfer system for stack molds comprises a sprue bar and a sprue bar sleeve, a sprue bar and drool restrictor and sleeve or a sprue bar and drool restrictor. For the assemblies with the sleeve, when the stack mold is opened, the sprue bar slides inside the sprue bar sleeve which captures any leakage therefrom. When the mold is closed, the sprue bar sweeps captured leakage out of the sleeve to an area outside the mold. As the busing at the end of the sprue bar can contact the nozzle of the injection machine at a point very close to the edge of the fixed platen, the resulting minimum length of the sprue bar is reduced, reducing pressure losses through the sprue bar and reducing the cost of the sprue bar. The sprue bar sleeve can be fabricated from an insulating material to enhance the thermal characteristics of the sprue bar assembly and a scraper can be provided on the sprue bar to improve removal of captured material from the sprue bar sleeve.

Abstract: The present invention relates to an apparatus for injection molding a thin-walled plastic article with substantially equal thickness sidewalls, a base portion, and a lip portion. The apparatus includes a two part mold arrangement in which a first part defines has a mold cavity and a second part defines a mold core. The first and second mold parts in a mold closed position define a mold space in the shape of the article being molded. The apparatus further includes two or more gates adjacent a lip portion of the mold space for injecting molten plastic material into the mold space and a bottom center venting arrangement. The apparatus further includes a restriction in the mold space for improving the operation of the bottom center venting arrangement and providing a more balanced filling in a multi-cavity molding machine.

Abstract: Apparatus includes a mold cavity and a molten plastic inlet channel for communication with the mold cavity for transmission of molten plastic to the mold cavity. A valve stem is provided with substantially no net resulting forces on the valve stem due to melt pressure acting on the projecting area of its upstream and downstream faces.

Abstract: Apparatus provides a large opening for rapid filling of a mold cavity and includes a heated injection nozzle adjacent the mold cavity, an elongated inlet conduit from the injection nozzle to the mold cavity, a channel in the heated injection nozzle communicating with the inlet conduit and cooling channels adjacent the inlet conduit to cool the inlet conduit operative to freeze resin in the inlet conduit after filling the mold cavity.