초록 ▼

An apparatus is disclosed for controlling operating pressure within a mold cavity of an injection molding die. Finely detailed, and parts having thin walls are molded with the invention providing a process for eliminating defects. There is a pressure control apparatus which is preset to provide vary

An apparatus is disclosed for controlling operating pressure within a mold cavity of an injection molding die. Finely detailed, and parts having thin walls are molded with the invention providing a process for eliminating defects. There is a pressure control apparatus which is preset to provide varying degrees of negative and positive pressure during the mold cycle, and to reset to repeat the procedure for subsequent cycles. The procedure includes a cleaning stage for preparing the mold cavity for the following mold cycle.

대표청구항 ▼

An apparatus for controlling operating pressure during predetermined increments of time in a mold cycle for producing intricate and thin wall plastic parts formed within a cyclical injection molding die operatively associated with an injection molding machine, said apparatus comprising: A. a mold ca

An apparatus for controlling operating pressure during predetermined increments of time in a mold cycle for producing intricate and thin wall plastic parts formed within a cyclical injection molding die operatively associated with an injection molding machine, said apparatus comprising: A. a mold cavity located between a mating male and female die member of said cyclical injection molding die, said mold cavity having an inlet port for receiving a heated thermoplastic material, B. a sealing device for insuring an airtight bond between said mating male and female die member during said mold cycle when said cyclical injection molding die is closed, C. a venting path for operatively applying a sustained negative pressure to said mold cavity during a first time interval beginning after said cyclical injection molding die has closed and before said cyclical injection molding die has filled with said heated thermoplastic material, D. first control means for maintaining a substantially constant negative pressure within said mold cavity during said first time interval of said mold cycle while said intricate, and thin walled parts are being formed, E. second control means for reversing said substantially constant negative air pressure to a positive air pressure and for maintaining said positive air pressure at a level sufficiently high enough during a second time interval of said mold cycle to cause a predetermined incremental and uniform separation of said intricate and thin walled plastic parts from said male and female die member at a predetermined increment of time substantially close to that portion of time in said mold cycle when said cyclical injection molding die initially opens, and F. means for resetting said first and second control means to an initial condition whereupon a succeeding mold cycle will be started.