Injection molding device

Abstract

An injection molding device and related method includes a mold plate with at least one pocket having at least one discharge opening to discharge melted plastic from the pocket into at least one mold cavity interconnected to the pocket and a nozzle including a housing, which during operation is interconnected to the pocket. Per discharge opening a needle is arranged displaceable in an axial direction in the housing between a closed position and an open position. In the closed position the needle closes the thereto related discharge opening and is thereby preventing melted plastic from flowing from the pocket into the at least one mold cavity. In the open position, the needle releases the discharge opening such that melted plastic flows from the pocket into the at least one mold cavity. Furthermore, a melt channel is discharging into the pocket to supply melted plastic into the pocket.

It is claimed: 
     
         1 . A method to inject melted plastic into a mold cavity, comprising:
 supplying melted plastic into a pocket formed between a housing of a nozzle and a mold plate via a melt channel ending in said pocket;   opening at least one discharge opening by axial displacement of at least one of a plurality of needles, each needle arranged in a corresponding discharge opening, wherein each needle is arranged displaceable in said axial direction in a corresponding needle bore in said housing;   injecting melted plastic from the pocket into a thereto interconnected mold cavity through the at least one discharge opening; and   closing the at least one discharge opening by moving at least one of the plurality of needles in an opposite direction.   
     
     
         2 . The method of  claim 1  wherein during operation one or more of the plurality of needles displaces in a radial direction with respect to its corresponding discharge opening to compensate mismatch. 
     
     
         3 . The method of  claim 2  wherein one or more of the plurality of needles displaces in a gap formed between each needle and its corresponding discharge opening and/or a gap between each needle and the housing. 
     
     
         4 . An injection molding device, comprising:
 a mold plate with at least one pocket having at least one discharge opening arranged to discharge melted plastic from said pocket into at least one mold cavity interconnected to said pocket during an injection molding operation;   at least one nozzle having a housing, which during the injection molding operation is interconnected to said pocket, and a plurality of discharge openings;   a plurality of needles, each needle corresponding to one of the plurality of discharge openings, and each needle arranged displaceable in an axial direction in said housing in a corresponding needle bore between:   a closed position in which the needle closes its thereto related discharge opening thereby preventing melted plastic from flowing from the pocket into the at least one mold cavity; and   an open position in which the needle releases its discharge opening such that melted plastic flows from the pocket into the at least one mold cavity; and   a melt channel alignable with the pocket and arranged to supply melted plastic into the pocket during the injection molding operation, wherein the melt channel is arranged to supply the melted plastic into the pocket independently of the plurality of needles arranged in the corresponding needle bores, and wherein the melt channel is oriented centralized between the plurality of needles in the housing.   
     
     
         5 . The injection molding device of  claim 4 , further comprising:
 a spacer arranged between the housing of the nozzle and the mold plate, the spacer arranged as one or both of a thermal isolator between the housing and the mold plate and a seal between the housing and the mold plate.   
     
     
         6 . The injection molding device of  claim 5  wherein the housing includes a shoulder arranged to support the spacer in the axial direction. 
     
     
         7 . The injection molding device of  claim 5  wherein the spacer includes a sealing lip extending in the axial direction with a first side facing the pocket and a second side, opposite of the first side, abutting against the mold-plate and forming a sealing surface. 
     
     
         8 . The injection molding device of  claim 4  wherein at least one melt channel is arranged at least partially in the housing of the nozzle. 
     
     
         9 . The injection molding device of  claim 4  wherein at least two needles are arranged offset to the melt channel. 
     
     
         10 . The injection molding device of  claim 4  wherein at least two needles are actuated by a common actuator. 
     
     
         11 . The injection molding device of  claim 4  wherein each discharge opening is arranged in a dimple. 
     
     
         12 . The injection molding device of  claim 11  wherein each dimple is at least partially shaped conical. 
     
     
         13 . The injection molding device of  claim 11  wherein the housing includes a bump arranged to cooperate with each dimple of the thereto related discharge opening. 
     
     
         14 . The injection molding device of  claim 13  wherein each bump is at least partially shaped conical. 
     
     
         15 . The injection molding device of  claim 11  wherein two neighboring dimples are spaced apart by a ridge. 
     
     
         16 . The injection molding device of  claim 15  wherein the melt channel is arranged aligned with at least one ridge, said ridge arranged to support distribution of the melted plastic between at least two discharge openings. 
     
     
         17 . The injection molding device of  claim 4  wherein at least one discharge opening, in an area where it interacts with its thereto related needle, has a diameter that is 0.02 mm to 0.5 mm larger than a diameter of its thereto related needle. 
     
     
         18 . The injection molding device of  claim 4  wherein more than one needle has a needle tip with a reduced diameter to interact with the discharge opening. 
     
     
         19 . The injection molding device of  claim 4 , further comprising:
 a distribution point is located on the mold plate opposite of the melt channel opening to the pocket.   
     
     
         20 . The injection molding device of  claim 19 , further comprising:
 a stream trough arranged to direct melted plastic from the distribution point towards at least one discharge opening in the pocket.