Multicavity injection molding apparatus having precision adjustment and shut off of injection flow to individual mold cavities

Claim 1

An injecting molding apparatus, said apparatus including structure defining a plurality of mold cavities; said apparatus further including an array of injection nozzles, each nozzle having a gate entering into a respective mold cavity; each injection nozzle having a longitudinal passage communicating with said gate, said mold apparatus including manifold means with runner passages for supplying said longitudinal passage of each injection nozzle with hot melt; a plurality of parallel, elongated valve pins each extending within the longitudinal passage of a respective nozzle, each valve pin having a tip aligned with a respective gate; a movable valve pin holder plate; valve pin mounting means mounting said valve pins to said holder plate to project lengthwise from said holder plate; actuation means connected to said holder plate for advancing and retracting said holder plate between retracted and fully advanced positions to move the tip of each of said valve pins into a respective gate to cause shut off of flow through each gate or to enable flow through each gate; said mounting means mounting said valve pins to said holder plate further including adjustment means which enables individual adjustment of the lengthwise position of each of said valve pins, so that lengthwise position of each valve pin may be individually fit to a respective gate to achieve complete flow shutoff when said holder plate is fully advanced; a plurality of elongated plunger sleeves, each sleeve surrounding a respective valve pin and having a tip portion lying within said longitudinal passage of a respective injection nozzle and located above a respective gate; plunger sleeve mounting means mounting each of said plunger sleeves to be longitudinally fixed within said respective injection nozzle; adjustment means allowing selective adjustment of the lengthwise position of each of said plunger sleeves in the longitudinal passage of said respective injection nozzle; said longitudinal passage of each injection nozzle including a shoulder adjacent said tip portion of a respective plunger sleeve, said shoulder together with said tip portion defining a variable restriction controlled by the adjusted lengthwise position of said plunger sleeve, whereby flow shutoff can be achieved by operation of said actuation means to move said valve pins into said gates, as well as individual flow adjustment to each valve gate by adjustment of each plunger sleeve.