Method and apparatus for stretching and crystallizing the neck finish of a molded plastic article
View Patent ↗Apparatus and method for making a molded plastic article having a stretched and crystallized neck finish. In one embodiment, a series of platforms are carried by a conveying apparatus for transporting a series of molded plastic articles along a predetermined path of travel through one or more treatment stations. At a finish widening station, the molded article, having a relatively wide and thin-walled blow-molded body portion, and a relatively narrow and thick-walled unexpanded neck finish portion, is positioned to enable insertion of a mandrel into an open top aperture of the finish portion to widen the finish.
1. Apparatus for treating a series of molded plastic articles, each article having a relatively wide and thin-walled blow-molded body portion and a relatively narrow and thick-walled unexpanded neck finish portion, the apparatus comprising:
a series of platforms carried by a conveying apparatus that transports the platforms along a predetermined path of travel through a finish widening station;
each platform having a top surface and a mating mechanism for engaging the body portion of one article, the top surface engaging a bottom surface and the mating mechanism engaging a sidewall surface of the body portion of the one article;
the finish widening station comprising a mandrel insertable within and removable from an open top aperture of the finish portion to widen the finish portion, wherein the mandrel has a lower tapered body portion insertable into the open top aperture of the finish portion for widening the neck finish portion from a first neck size to an expanded second neck size and the mandrel further includes a cooled upper body portion of the second expanded neck size for cooling the expanded neck finish portion; and
the mating mechanism adjustably receiving and engaging against the sidewall portion to hold the one article in a steady position relative to the platform during insertion and removal of the mandrel from the aperture.
2. The apparatus of claim 1 , wherein the mating mechanism comprises two or more fingers extending upwardly from the top surface of the platform and forming a recess between the fingers that engages the sidewall portion.
3. The apparatus of claim 2 , wherein the fingers are adjustably mounted on the platform to move along a path toward and away from a more central point of the platform, the fingers being fixable at selected positions along the path of movement.
4. The apparatus of claim 1 , wherein one or more of the platform and mandrel are rotatable for rotating the finish portion with respect to the mandrel.
5. The apparatus of claim 1 , wherein the lower body portion of the mandrel is heated by a flow of fluid through channels in the lower body portion.
6. The apparatus of claim 5 , wherein the upper body portion is cooled by a flow of fluid through channels in the upper body portion.
7. The apparatus of claim 6 , wherein the mandrel includes an external cooling mechanism for directing a cooling fluid into contact with an exterior surface of the widened finish portion.
8. The apparatus of claim 7 , wherein the external cooling mechanism provides a ring of cooling fluid to and around the exterior surface of the widened finish portion.
9. The apparatus of claim 8 , wherein the external cooling mechanism comprises a collar mounted on the upper body portion of the mandrel.
10. The apparatus of claim 8 , wherein the cooling fluid provided by the external cooling mechanism is air.
11. The apparatus of claim 6 , wherein the fluid in the channels of the upper body portion is cold water.
12. The apparatus of claim 5 , wherein the fluid in the channels of the lower body portion is hot water.
13. The apparatus of claim 1 , wherein the predetermined path of travel includes a finish crystallizing station comprising a heating device that heats the widened finish portion for a time and temperature selected to crystallize at least a portion of the widened finish portion.
14. The apparatus of claim 13 , wherein the finish crystallizing station includes a sizing device insertable within and removable from the widened finish portion.
15. The apparatus of claim 1 , wherein the treated molded plastic articles are food or beverage containers.
16. The apparatus of claim 1 , wherein the upper body portion is cooled by a flow of fluid through channels in the upper body portion.
17. The apparatus of claim 1 , wherein the mandrel includes an external cooling mechanism for directing a cooling fluid into contact with an exterior surface of the widened finish portion.
18. The apparatus of claim 1 , wherein an outer surface of the mandrel comprises a low friction material.
19. The apparatus of claim 1 , wherein the upper body portion of the mandrel is cylindrical.
20. The apparatus of claim 1 , wherein the mandrel is rotatable.