Blow molding method
OwnerRobert X. Hafeleinventor
Life of this patent
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Abstract
A method and apparatus are disclosed for forming thermoplastic articles in which preforms are injection molded interiorly of mold cavities around substantially cylindrical core pins on a rotatable turret. The turret is then indexed to displace the core pins to a second position and the preforms are retained on the core pins during indexing and thereafter to cool the preforms to a self sustaining condition. To enhance cooling, the preforms may be engaged by temperature conditioning molds while on the core pins. After adequate cooling, the preforms are removed from the core pins and positioned on carrier sleeves. The preforms are then thermally conditioned on the carrier sleeves to a predetermined temperature, following which they are blow molded in blow mold cavities.
Claims13
In a method of forming a plurality of thermoplastic articles, the steps of:
- (a) injection molding a plurality of essentially tubular, thermoplastic preforms at a first position interiorly of a plurality of mold cavities around a plurality of substantially cylindrical core pins mounted on a rotatable turret, thereby forming preforms having at least one open end;
- (b) indexing the turret to displace the core pins from the first position to a second position;
- (c) retaining the preforms on the core pins during the indexing step to cool the preforms;
- (d) maintaining the inner surfaces of the preforms in contact with the core pins while engaging the outer surface of the preforms with a set of molds having inner dimensions substantially equivalent to the outer dimensions of the preforms, and thereby cooling the preforms to an essentially self-sustaining condition by transferring heat from both the inner and outer surfaces of the preforms respectively to the associated core pins and the set of the molds;
- (e) removing the preforms from the core pins;
- (f) positioning the preforms in carrier blocks substantially aligned with the core pins and displacing the carrier blocks to space the preforms further apart preparatory to blow molding;
- (g) telescopically inserting a plurality of respective carrier sleeves into the preforms as spaced apart by the performance of step (f);
- (h) thermally conditioning the preforms while on the carrier sleeves to a temperature conducive to blow molding;
- and
- (i) blow molding the preforms within a plurality of blow mold cavities.
In a method of injection molding a plurality of thermoplastic preforms and then blow molding the preforms into a plurality of articles, the steps of:
- (a) injection molding a plurality of thermoplastic preforms around a first set of generally axially aligned vertically oriented core pins at a first station in an injection cavity formed by injection mold sections closed around the core pins;
- (b) opening the injection mold sections after the molded preforms are formed and cooled sufficiently to be transported on the core pins;
- (c) transporting the injection molded preforms on the first set of core pins from the first station and cooling the preforms by heat transfer to the core pins;
- (d) during the performance of step (c), transporting a second set of generally axially aligned core pins to the first station so that the injection mold halves may be closed around those core pins for the formation of a subsequent set of molded preforms;
- (e) maintaining the inner surfaces of the preforms in contact with the core pins while engaging the outer surfaces of preforms with a set of molds having inner dimensions substantially equivalent to the outer dimensions of the preforms, and thereby cooling the preforms to an essentially self-sustaining condition by transferring heat from both the inner and outer surfaces of the preforms respectively to the associated core pins and the set of molds;
- (f) at a second station, after the performance of step (e), downwardly displacing the molded preforms in a vertically oriented position from the first set of core pins to a set of transporting blocks generally vertically aligned with the core pins, and pendantly supporting the preforms with the transporting blocks;
- (g) after the performance of step (f), displacing the first set of core pins away from the second station and toward the first station while simultaneously displacing the second set of core pins from the first station preparatory to performance of step (f) with respect to the second set of core pins;
- (h) successively repeating the performance of steps (a)-(g) in a continuous operational cycle to form successive sets of generally axially aligned preforms and then transferring each successive set to the transporting blocks;
- (i) after the receipt of each successive set of preforms, laterally displacing the transporting blocks from the position in general alignment with the core pins and moving the blocks along the axis of the aligned preforms to space the preforms a greater distance from each other in preparation for a blow molding step;
- and
- (j) blow molding each successive set of preforms interiorly of a set of blow mold cavities to form a plurality of blown plastic articles.
Dependencies are inferred from the claim text.