Back to results
US 5,281,385 AGranted
Injection molding system for threaded tamper indicating closures
AssigneeSunbeam Plastics Corporation
InventorRandall K. Julian
Life of this patent
Estimating the term…
Abstract
A method of injection molding a container cap with a precision thread having a tamper indicating band depending from the bottom of the cap skirt. Collet jaws form at least a frangible connection between the bottom of the cap skirt and the top of the tamper indicating band, and these jaws are moved radially outward specified amounts during the molding process to provide clearance for stripping an inwardly directed retaining element on the band from the core and for ejection of the finished cap.
Claims26
A method of molding a plastic tamper indicating closure having a threaded cap and a tamper indicating band joined to the bottom of the cap by a frangible connection, said method comprising the following steps:
- a) providing a cavity mold defining an exterior portion of said cap;
- b) providing a core defining an internal thread of said cap and an inwardly directed retaining element on said tamper indicating band;
- c) providing a circumferential array of radially movable jaws concentrically around said core, said jaws, when in a radially innermost position, defining the exterior surface and bottom of said tamper indicating band, the bottom of said cap and the frangible connection between said tamper indicating band and the bottom of said cap;
- d) axially moving said core and array of jaws into said cavity mold;
- e) moving said jaws into their radially innermost position and locking said jaws in said position completing delineation of a molding cavity for said closure;
- f) injecting plastic material into said molding cavity to form said closure;
- g) moving said jaws radially outward a predetermined amount to provide clearance for stripping of the retaining element on said tamper indicating band from said core;
- h) rotating said core in an unthreading direction while restraining rotation of said closure;
- i) axially advancing said array of jaws while maintaining contact between each of said jaws and the bottom of the tamper indicating band and the bottom of the cap of said closure to strip said cap from said core as said core is being rotated;
- and
- j) moving said jaws radially outward a further, amount than the predetermined amount of step
- g) and ejecting said closure.
9 more elements
A method of molding a plastic tamper indicating closure having a threaded cap and a tamper indicating band joined to the bottom of the cap by a frangible connection, said method comprising the following steps:
- a providing a cavity mold defining an exterior portion of said cap;
- b) providing a core defining an internal thread of said cap and an inwardly directed retaining element on said tamper indicating band;
- c) providing a collet concentrically around said core having radially spring biased axially extending fingers forming a circumferential array of jaws, the collet when in its closed position, defining the exterior surface and bottom of said tamper indicating band, the bottom of said cap with a plurality of unthreading teeth and the frangible connection between said tamper indicating band and the bottom of said cap;
- d) axially moving said core and said collet into said cavity mold and closing said collet thereby defining a molding cavity for said closure;
- e) injecting plastic material into said molding cavity to form said closure;
- f) moving said cavity mold axially with respect to said collet so that said cavity mold lies axially beyond said closure;
- g) partially opening said collet a predetermined amount to provide clearance for stripping of the retaining element on said tamper indicating band from said core but maintaining engagement of the jaws with the plurality of unthreading teeth;
- h) rotating said core in an unthreading direction while said unthreading teeth restrain rotation of said closure;
- i) axially advancing said collet while maintaining contact between each of said jaws and the bottom of the tamper indicating band and the bottom of the cap of said closure to strip said cap from said core as said core is being rotated;
- and
- j) opening said collet a further amount than the predetermined amount of step g) disengaging said unthreading teeth from said closure and ejecting said closure.
8 more elements
A method of molding a plastic tamper indicating closure having a threaded cap and a tamper indicating band joined to the bottom of the cap by a frangible connection, said method comprising the following steps:
- a) providing a cavity mold defining an exterior portion of said cap with a circumferential array of axially extending ribs;
- b) providing a core defining an internal thread of said cap and an inwardly directed retaining element on said tamper indicating band;
- c) providing a collet concentrically around said core having radially spring biased axially extending fingers forming a circumferential array of jaws when the collet is in its closed position, defining the exterior surface and bottom of said tamper indicating band, the bottom of said cap and the frangible connection between said tamper indicating band and the bottom of said cap;
- d) axially moving said core and said collet into said cavity mold and closing said collet thereby defining a molding cavity for said closure;
- e) injecting plastic material into said molding cavity to form said closure;
- f) moving said cavity mold axially with respect to said collet so as to release the collet jaws from their closed position but maintaining engagement of said ribs with the cavity mold;
- g) partially opening said collet a predetermined amount to provide clearance for stripping of the retaining element on said tamper indicating band from said core but maintaining engagement of the jaws with the bottom of the cap and the bottom of the tamper indicating band;
- h) rotating said core in an unthreading direction of said closure while said ribs restrain rotation of said closure;
- i) axially advancing said collet while maintaining contact between each of said jaws and the bottom of the tamper indicating band and the bottom of the cap of said closure to strip said closure from said core as said core is being rotated;
- j) axially moving said cavity mold away from said collet, releasing said cap ribs;
- and
- k) opening said collet a further amount than the predetermined amount of step g) disengaging said collet from the bottom of said cap and the bottom of said tamper indicating band and ejecting said closure.
9 more elements
Dependencies are inferred from the claim text.