Swage-forming of container or preform internal threads
A method of making a plastic container having a body and an internally threaded finish includes providing a preform of molded plastic construction having a body and an integral neck, and expanding the body of the preform within a mold cavity to form the body of the container. Either prior to or subsequent to blow molding the container body, at least one internal thread is formed in the neck by engaging an inner surface of the neck with a first rotary tool having a peripheral channel, engaging an outer surface of the neck with a second rotary tool having a peripheral bead, and causing rotation of the neck and tools to swage at least one internal thread in the neck.
1 . A method of making a plastic container having a body and an internally threaded finish, which includes the steps:
(a) providing a preform of molded plastic construction having a body and an integral neck,
(b) expanding said body of said preform within a mold cavity to form said body of said container, and
(c) either prior to or subsequent to said step (b), forming at least one internal thread in said neck by:
(c1) engaging an inner surface of said neck with a first rotary tool having a peripheral channel,
(c2) engaging an outer surface of said neck with a second rotary tool having a peripheral bead, and
(c3) causing rotation of said neck and said tools to swage at least one internal thread in said neck.
2 . The method set forth in claim 1 wherein said step (c) includes heating one or both of said tools.
3 . The method set forth in claim 1 which includes the step, following said step (c3), of:
(d) placing a finish ring with at least one external thread over said neck to form a container having a finish with both internal and external threads.
4 . The method set forth in claim 1 wherein said step (a) includes providing at least one molded external thread on said neck, such that said neck has at least one external thread and at least one internal thread following said step (c).
5 . A method of making an internally threaded finish on a plastic preform or container, which includes the steps of:
(a) providing a plastic neck on the preform or container without internal threads, and
(b) forming at least one internal thread in said neck by:
(b1) engaging an inner surface of said neck with a first rotary tool having a peripheral channel,
(b2) engaging an outer surface of said neck with a second rotary tool having a peripheral bead, and
(b3) causing rotation of said neck and said tools to swage at least one internal thread in said neck.
6 . The method set forth in claim 5 wherein said step (c) includes heating one or both of said tools.
7 . The method set forth in claim 5 which includes the step, following said step (c3), of:
(d) placing a finish ring with at least one external thread over said neck to form a container having a finish with both internal and external threads.
8 . The method set forth in claim 5 wherein said step (a) includes providing said neck with at least one external thread, such that said neck has at least one external thread and at least one internal thread following said step (c)
9 . A plastic container made in accordance with the method set forth in claim 1 .
10 . A finish on a plastic container or preform made in accordance with the method set forth in claim 5 .
11 . A finish on a plastic container or preform made in accordance with the method set forth in claim 8 .
12 . A finish on a plastic container or preform, which includes:
a cylindrical neck of substantially uniform wall thickness and having at least one internal thread, and
a finish ring secured over said neck and having at least one external thread.
13 . A finish on a plastic container or preform, which includes:
a cylindrical neck having at least one internal thread and at least one external thread.
14 . The finish set forth in claim 13 wherein said neck is of molded plastic construction, said at least one external thread is integrally molded with said neck, and said at least one internal thread is swage-formed on said neck.