System and method for continuous injection molding
A carousel-like continuous molding system includes an arrangement of inclined feed channels. Each of the feed channels has a controllable valve therein positioned upstream of an inlet to an associated mold cavity. The valve is controllable so that adjustments may be made in real time to achieve or maintain delivery of molten polymeric material to the mold cavity at constant pressure.
1. A method of injection molding comprising:
advancing at least one of a plurality of mold cavity and mold core pairs along a continuous cam track, each of the mold cavity and mold core pairs being actuatable between an open condition along a first portion of the cam track and a closed condition along a second portion of the cam track;
subsequent to the at least one of the plurality of actuatable mold cavity and mold core pairs being actuated to the closed condition, bringing an inlet of a mold cavity of the at least one of the plurality of actuatable mold cavity and mold core pairs into communication with a respective one of a plurality of inclined feed channels, the inclined feed channels being disposed in a conical distribution and being in fluid communication with a nozzle, the nozzle being at a different elevation than the inlet of the mold cavity of at least one of the plurality of actuatable mold cavity and mold core pairs;
while the at least one of the plurality of mold cavity and mold core pairs is still in the closed condition and advancing along the second portion of the cam track, actuating, from a closed position to an open position, a controllable valve that selectively permits fluid communication from the respective one of the plurality of inclined feed channels to the inlet of the mold cavity of the at least one of the plurality of actuatable mold cavities and mold core pairs;
continuously feeding a supply of molten polymeric material to the nozzle in fluid communication with the respective one of a the plurality of inclined feed channels while the at least one of the plurality of mold cavity and mold core pairs continues to advance along the second portion of the cam track, thereby introducing the molten polymeric material into the mold cavity of the at least one of the plurality of mold cavity and mold core pairs;
actuating the controllable valve from the open position to the closed position to discontinue introducing the molten polymeric material into the mold cavity of the at least one of the plurality of mold cavity and mold core pairs;
prior to the at least one of the plurality of actuatable mold cavity and mold core pairs being actuated to the open condition, bringing the inlet of the mold cavity of the at least one of the plurality of actuatable mold cavity and mold core pairs out of communication with the respective one of the plurality of inclined feed channels; and
further advancing the at least one of the plurality of mold cavity and mold core pairs along the continuous cam track until the at least one of the plurality of mold cavity and mold core pairs reaches the first portion of the cam track, thereby opening the at least one of the plurality of mold cavity and mold core pairs.
2. The method of claim 1 , and in continuously feeding the supply of molten polymeric material to the nozzle, dividing the molten polymeric material from the nozzle into the plurality of inclined feed channels, the plurality of inclined feed channels including a second one of the plurality of inclined feed channels in communication with a second at least one of the plurality of actuable mold cavity and mold core pairs.
3. The method of claim 1 , wherein a sprue is provided intermediate the respective one of the plurality of inclined feed channels and the at least one of the plurality of actuable mold cavity and mold core pairs.
4. The method of claim 1 , further comprising rotating the respective one of a plurality of inclined feed channels about the nozzle.
5. The method of claim 1 , wherein the second portion of the cam track is disposed in an arcuate arrangement relative to the nozzle.
6. The method of claim 1 , wherein the cam track is disposed in a circular arrangement relative to the nozzle.
7. The method of claim 1 , and in continuously feeding the supply of molten polymeric material to the nozzle, the continuous feeding includes extrusion of the molten polymeric material.
8. The method of claim 1 , further comprising metering the flow of molten polymeric material in to the at least one of the plurality of actuable mold cavity and mold core pairs through one of a metering gate or a controllable valve.
9. The method of claim 1 , further comprising cooling the molten polymeric material in the at least one of the plurality of actuable mold cavity and mold core pairs.
10. The method of claim 9 , wherein a molded part is ejected from the mold cavity of the at least one of the plurality of actuatable mold cavity and mold core pairs when the at least one of the plurality of actuatable mold cavity and mold core pairs is in the open condition.
11. The method of claim 10 , wherein the molded part is ejected after the molten polymeric material in the at least one of the plurality of actuable mold cavity and mold core pairs is cooled.
12. The method of claim 8 , and in metering the flow of molten polymeric material in to the at least one of the plurality of actuable mold cavity and mold core pairs, adjusting the metering gate or controllable valve in the respective one of the plurality of inclined feed channels to a different extent than that to which the metering gate or controllable valve in a second one of the plurality of inclined feed channels is adjusted.