Continuous production of molded plastic containers
View Patent ↗A system for making plastic containers includes a source for providing a continuous stream of molten plastic, and a cutter for severing a continuing series of individual mold charges from the continuous molten plastic stream. A compression molder includes a plurality of compression molds arranged in a continuing series for receiving the mold charges in sequence and compression molding the mold charges into a continuing series of individual plastic container preforms. A blow molder includes a plurality of blow molds arranged in a continuing series for receiving the individual plastic container preforms in sequence and blow molding the preforms into a continuing series of plastic containers. A common drive coordinates continuous and synchronous operation of the molten plastic source, the cutter, the compression molder and the blow molder to provide the continuing series of plastic containers from the continuous stream of molten plastic.
1. A system for making plastic containers, which includes:
a source for providing a continuous stream of molten plastic,
a compression preform molder for molding said plastic into a continuing series of individual plastic container preforms,
a blow molder including a plurality of blow molds arranged in a continuing series for receiving said individual plastic container preforms in sequence and blow molding said preforms into a continuing series of plastic containers, and
a common drive connected to and coordinating continuous and synchronous operation of said source, said compression molder and said blow molder.
2. The system set forth in claim 1 wherein said common drive includes a drive/control mechanism connected to a drive of said source, a drive of said compression molder, and a drive of said blow molder.
3. The system set forth in claim 2 wherein said drive/control mechanism includes servo control electronics for synchronizing operation of servo motors connected to said source, said compression molder, and said blow molder.
4. The system set forth in claim 2 wherein said drive/control mechanism comprises a single motor connected by drive mechanisms to operating mechanisms of said source, said compression molder, and said blow molder.
5. The system set forth in claim 1 wherein said source comprises an extruder which provides said continuous stream.
6. The system set forth in claim 1 further including a preform conditioner connected between said compression molder and said blow molder for conditioning performs from said compression molder preparatory to blow molding in said blow molder, and wherein said common drive is also connected to and coordinates continuous and synchronous operation of said conditioner.
7. The system set forth in claim 6 wherein said preform conditioner includes a loop around which said preforms travel and wherein said common drive is connected to and coordinates continuous and synchronous operation of said loop.
8. The system set forth in claim 6 further including a transfer device connected to said preform conditioner for conveying said conditioned preforms to said blow molder, and wherein said common drive is also connected to and coordinates continuous and synchronous operation of said transfer device.
9. The system set forth in claim 1 further including a conveyer connected to said blow molder for receiving said continuing series of plastic containers from said blow molder, and wherein said common drive is also connected to and coordinates continuous and synchronous operation of said conveyer.
10. The system set forth in claim 1 wherein said compression molder includes a turret carrying a plurality of compression molds for receiving a continuous series of mold charges in sequence cut from said stream and compression molding the charges into said continuous series of preforms, and wherein said common drive is also connected to and coordinates continuous and synchronous operation of said compression molder turret.
11. The system set forth in claim 1 wherein said blow molder includes a turret carrying said plurality of blow molds and wherein said common drive is also connected to and coordinates continuous and synchronous operation of said blow molder turret.
12. The system set forth in claim 1 wherein said compression molder molds multiple performs at each mold stage.
13. The system set forth in claim 1 wherein said blow molder molds multiple containers at each mold stage.
14. The system set forth in claim 1 including a cutter for severing a continuing series of individual mold charges from said continuous stream, and wherein said common drive is connected to and coordinates continuous and synchronous operation of said cutter.
15. A method of making plastic containers, which includes the steps of:
(a) providing a continuous stream of molten plastic,
(b) compression molding said plastic into a continuing series of plastic container preforms,
(c) transferring said continuing series of plastic container preforms in sequence to a continuing series of blow molds,
(d) blow molding a continuing series of plastic containers in said blow molds,
(e) removing said containers in sequence from said blow molds, and
(f) operating said steps (a) through (e) in synchronism to provide a continuing series of blow molded containers from said molten plastic stream.
16. The method set forth in claim 15 wherein said step (c) includes conditioning said plastic container performs preparatory to blow molding in said step (d).
17. The method set forth in claim 15 that includes at least one step, prior to said step (c) or subsequent to said step (e), selected from the group consisting of:
crystallizing all or a portion of a finish of the preform or container, and attaching all or a portion of a finish to the preform or container.
18. The method set forth in claim 15 that includes the step of attaching a label to the container during or subsequent to said step (d).
19. The method set forth in claim 15 wherein after said step (d) the preforms are transferred to a conditioning stage where they are allowed to cool to a temperature suitable for blow molding.
20. The method set forth in claim 19 wherein said step (f) includes operating said steps (a) through (e) in synchronism with said conditioning step.
21. The method set forth in claim 15 wherein after said step (d) the preforms are transferred to a conditioning stage where they are heated to a temperature suitable for blow molding.
22. The method set forth in claim 15 wherein during said step (b) multiple preforms are compression molded in a single mold cycle.
23. The method set forth in claim 15 wherein during said step (d) multiple containers are blow molded in a single mold cycle.
24. The method set forth in claim 15 wherein said step (f) of operating in synchronism comprises connecting a common or integrated drive/control mechanism to a drive of an extruder for providing said continuous stream of molten plastic, a drive of a compression molder turret carrying a plurality of compression molds for said step of compression molding of said preforms, a drive of a transfer device for said step of transferring of said preforms to said blow molds, a drive of a blow molder turret carrying said blow molds, and a drive of a conveyer for said step of removing said containers from said blow molds.
25. The method of claim 15 including the step of cutting such continuous stream into individual mold charges and transferring said mold charges in sequence to a continuing series of compression molds for said step of compression molding, and wherein said operating step (f) includes operating said cutting step in synchronism with steps (a) through (e).
26. The method set forth in claim 15 wherein the continuous stream of molten plastic is fed to a cutter and transfer mechanism for severing a continuing series of individual mold charges from said stream and transferring the mold charges into individual compression molds carried by a turret which is operated in synchronism with the cutter and the transfer mechanism.