US 5,292,243 AGranted

Apparatus for heating portions of container preforms

AssigneeCincinnati Milacron Inc.

InventorJoseph F. Gibbemeyer

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Abstract

Apparatus for heating longitudinally extending portions of a blow molding preform in order to provide a non-symmetrical temperature distribution about a longitudinal axis of the preform. The non-symmetrical temperature distribution permits the preform to be blown to form a non-symmetrical article that has an essentially uniform wall thickness distribution. An auxiliary heating and transfer station is provided between a reheating station and a blowing station, the auxiliary heating and transfer station including two side-by-side pairs of heating elements that are adapted to heat sequentially, corresponding sides of each of a pair of side-by-side blow molding preforms carried by a pallet. The two zone auxiliary heating arrangement permits the desired temperature rise to be achieved consistently while retaining some process flexibility. One or more of the heating elements in the second zone of the auxiliary heating and transfer station is mounted in a manner which allows it to be temporarily repositioned out of the preform movement path. In the preferred embodiment a pivotable turntable is used to shift the associated heating element by 90.degree., thereby permitting transverse movement of the pallet and associated preforms in a direction toward the blow molding station.

Claims13

Dependent claims

Apparatus for heating selected surfaces of a blow molding preform to a higher temperature than adjacent surfaces, said apparatus comprising:

a. a supporting frame;
a plurality of pallets, each of the pallets supporting a pair of container preforms in side-by-side relationship and conveying the container preforms along a preform movement path which includes a lateral shift, the pallets being supported for movement along the supporting frame;
c. a reheat station carried by the supporting frame for uniformly heating container preforms from ambient temperature to a desired first elevated temperature to soften the preforms for later blowing in a blow mold;
d. an auxiliary heating station carried by the supporting frame, downstream from and adjacent the reheat station, the auxiliary heating station including a plurality of heating elements adjustably positioned and geometrically configured to heat a selected circumferential area of the preforms to a desired second elevated temperature greater than the desired first elevated temperature to provide a non-symmetrical circumferential temperature distribution within the preform, at least one heating element in the auxiliary heating station being movable to a position out of the preform movement path;
and
e. a blowing station carried by the supporting frame, downstream from and adjacent the auxiliary heating station, for introducing pressurized air into the preforms while the preforms are within a non-symmetrical mold cavity to expand the preforms to conform with the walls of the cavity, the temperature distribution in the preform allowing expansion of the preform within the mold cavity to provide a blown article with substantially uniform wall thickness in a transverse plane.

3 more elements

Apparatus for heating selected surfaces of a blow molding preform to a higher temperature than adjacent surfaces, said apparatus comprising:

a. a supporting frame;
b. a plurality of pallets, each of the pallets supporting a pair of container preforms in side-by-side relationship and conveying the container preforms along a preform movement path which includes a lateral shift, the pallets being supported for movement along the supporting frame;
c. a reheat station carried by the supporting frame for uniformly heating container preforms from ambient temperature to a desired first elevated temperature to soften the preforms for later blowing in a blow mold;
d. an auxiliary heating station carried by the supporting frame, downstream from and adjacent the reheat station, the auxiliary heating station including two pairs of laterally spaced auxiliary heating elements to define first and second auxiliary heating zones to heat a selected circumferential area of the preform to a desired second elevated temperature grater than the desired first elevated temperature to provide a non-symmetrical circumferential temperature distribution within the preform, the second auxiliary heating zone including a second auxiliary heater that is movable to a position out of the path of movement of a respective preform;
and
e. a blowing station carried by the supporting frame, downstream from and adjacent the auxiliary heating station, for introducing pressurized air into the preforms while the preforms are within a non-symmetrical mold cavity to expand the preforms to conform with the walls of the cavity, the temperature distribution in the preform allowing expansion of the preform within the mold cavity to provide a blown article with substantially uniform wall thickness in a transverse plane.

3 more elements

Dependencies are inferred from the claim text.