Method and apparatus for feeding granulated material

Abstract

Method and apparatus are disclosed for cyclically metering charges of a granulated wax-like or resinous material from a bulk supply and feeding such metered charges into a heated, pressurized reservoir. Each charge of the granulated material is fluidized with a stream of air under pressure to insure flow of the granules. The stream of air also serves to pressurize the reservoir and prevent the escape of hot air therefrom. Cooling of the reservoir inlet to prevent agglutination of the granules also is contemplated.

What is claimed is: 
     
       1. In .[.an.]. .Iadd.apparatus for .Iaddend.injection .[.apparatus.]. .Iadd.molding thermoplastic material .Iaddend.having a pair of relatively movable dies, .[.means including.]. a pressurized heated tank for supplying molten .Iadd.thermoplastic .Iaddend.injection material to the dies, .[.and.]. means for causing relative movement of the dies between open and closed positions, .Iadd.and injection means for transferring molten thermoplastic material from the tank to the dies when in closed position .Iaddend.the improvement .[.of a feeder for periodically supplying charges of solid granules of injection material to said tank, said feeder.]. comprising: a. .[.A.]. .Iadd.a .Iaddend.housing having an inlet port .[.and.]. .Iadd.adapted to be connected to a supply of granular thermoplastic material, .Iaddend.an outlet port .[.communicating.]. .Iadd.adapted to be connected .Iaddend.with .[.said.]. .Iadd.the .Iaddend.tank, .Iadd.and a pressure port spaced from said outlet port; .Iaddend.   b. .Iadd.transfer .Iaddend.means .[.containing a supply of granules communicating with said inlet port.]. .Iadd.in said housing.Iaddend.;   c. .Iadd.said .Iaddend.transfer means .[.including a metering chamber.]. .Iadd.being .Iaddend.movable .[.in said housing.]. between.Iadd.: (i) .Iaddend.a first position in which said .[.chamber receives a quantity of granules.]. .Iadd.transfer means can receive granular thermoplastic material .Iaddend.admitted through said inlet port.Iadd.; .Iaddend.and   .Iadd.(ii) .Iaddend.a second position in which said .[.chamber discharges a charge of granules.]. .Iadd.transfer means can discharge granular thermoplastic material .Iaddend.through said outlet port .Iadd.into the tank.Iaddend.;     d. means for actuating said transfer means, and   e. .[.means for pressurizing.]. .Iadd.said pressure port communicating with said outlet port when said transfer means is in said first and second positions .Iaddend.via said .[.metering chamber to fluidize the granules of injection material contained therein when said transfer means is in said second position.]. .Iadd.transfer means, whereby discharge of granular thermoplastic material from the transfer means can be assisted by pressurized gas and pressurized gas is trapped in said transfer means and released through said inlet port when said transfer means is moved to said first position to assist the flow of granular thermoplastic material into said transfer means and whereby the tank is pressurized with gas admitted thereto through said outlet port.Iaddend..   
     
     
       2. The improvement as claimed in claim 1 wherein when said transfer means is in its second position, a portion of said transfer means closes said inlet port. 
     
     
       3. The improvement as claimed in claim 1 wherein said means for actuating said transfer means is .Iadd.adapted to be .Iaddend.operatively connected to said die moving means, whereby a charge of granules is supplied to said tank in response to movement of said dies. 
     
     
       4. The improvement as claimed in claim 3 wherein .[.an.]. .Iadd.each .Iaddend.amount of molten .[.injection.]. material .[.is.]. withdrawn from the tank and injected into the dies in their closed position.[., and wherein each amount of molten material withdrawn from the tank.]. approximately equals the size of each granular charge supplied to the tank. .[.5. In an injection apparatus having a pair of relatively movable dies, means for causing relative movement of the dies between open and closed position, and means including a pressurized heated tank for supplying molten injection material to the dies in their closed position, the improvement of a feeder for periodically supplying charges of solid granules of injection material to said tank, said feeder comprising: a. a housing having an inlet port and an outlet port communicating with said tank,   b. means containing a supply of granules communicating with said inlet port,   c. transfer means including a metering chamber movable in said housing between a first position in which said chamber receives a quantity of granules admitted through said inlet port and a second position in which said chamber discharges a charge of granules through said outlet port,   d. means for actuating said transfer means, and   e. means for supplying gas under pressure to said metering chamber and to   
     
     
        said inlet and outlet ports within said housing..]. .[.6.  The improvement as claimed in claim 5 wherein when said transfer means is in its second position, a portion of said transfer means closes said inlet port..]. .[.7. The improvement as claimed in claim 5 wherein said pressurized gas supplied to the outlet port is admitted to said tank to pressurize it..]. 
     
     
         . The improvement as claimed in claim .[.5.]. 
     
     
       .Iadd.1 .Iaddend.including means for selectively changing said second position of said transfer means in order to .[.measure.]. .Iadd.change .Iaddend.the .[.charges.]. .Iadd.amount .Iaddend.of .[.granules.]. .Iadd.granular thermoplastic material .Iaddend.discharged from said .[.metering chamber.]. .Iadd.transfer means .Iaddend.through said outlet port. .[.9. In an injection apparatus having a pair of relatively movable dies, means including a pressurized heated tank for supplying molten injection material to the dies, and means for causing relative movement of the dies between open and closed positions, the improvement of a feeder for periodically supplying measured charges of solid granules of injection material to said tank, said feeder comprising: a. a housing having inlet and outlet ports, said outlet port communicating with said tank,   b. means containing a supply of granules communicating with said inlet port,   c. transfer means in said housing having a metering chamber,   d. said transfer means being movable between a first position in which said chamber is disposed in communicating with said inlet port to receive a quantity of granules and a variable second position in which at least part of said chamber overlaps said outlet port,   e. means for varying said second position of said transfer member in order to selectively measure the charge of granules metered from said chamber through said outlet port, and   f. means for actuating said transfer member between said first and second   
     
     
        positions..]. .[.10.  The improvement as claimed in claim 9 including means for supplying gas under pressure to said metering chamber and permitting the gas to be communicated to said inlet and outlet ports via said chamber when said transfer means is in said first and second 
     
     
        positions, respectively..]. 11. In an injection apparatus having a pair of relatively movable dies, means for causing relative movement of the dies between open and closed positions, and a pressurized heated tank for supplying molten injection material to the dies in their closed position, the method of feeding granulated wax-like injection molding material to the tank for melting and subsequent injection comprising: a. separating relatively small quantities of the granulated material from a bulk supply thereof;   b. fluidizing the relatively small quantities with .[.air.]. .Iadd.gas .Iaddend.under pressure .Iadd.from a source independent of the tank .Iaddend.to prevent agglutination of the granules;   c. metering a charge of predetermined size from each fluidized quantity; and   
     
     
       d. depositing each such metered charge in the tank. 12. The method of claim 11 and further comprising the step of depositing each such metered charge in the tank in response to withdrawal of molten injection material from the tank by the injection apparatus for .[.injecion.]. .Iadd.injection 
     
     
        .Iaddend.into the dies in their closed position. 13. The method of claim 11 and further comprising the step of admitting pressurized .[.air.]. .Iadd.gas .Iaddend.into the tank with each metered charge. .Iadd.14. A method of feeding granular thermoplastic material comprising the steps of: a. introducing material into a transfer means through an inlet port,   b. moving said material to an outlet port,   c. discharging at least part of said material from said transfer means through the outlet port, and   d. introducing pressurized gas into said transfer means through a pressure port spaced from said outlet port to assist in discharging said material from said transfer means. .Iaddend.