Method for molding hollow plastic articles

A method of making plastic articles from a thermoplastic resin material which comprises the steps of:

• extruding plasticized resin continuously from an extruder to form a continuous stream of hot plasticized material;
• sequentially feeding the continuous stream of plasticized material to a plurality of preform molds disposed in at least two sets of molds having two or more molds in each set;
• sequentially forming a plurality of preforms in the molds;
• transferring each of the preforms from the molds to blowing apparatus before the preforms cool substantially, the preforms from each set of two or more molds being transferred directly to a single blowing apparatus, there being a separate blowing apparatus for each set of molds;
• and
• blowing each preform into the plastic article in the blowing apparatus.

A method of making plastic articles from a thermoplastic resin material, which comprises the steps of:

• extruding hot plasticized resin;
• feeding the plasticized resin sequentially into alternate molds of a plurality of preform molds disposed in at least two sets of two or more molds each;
• forming preforms in each mold;
• transferring the preforms while they are still warm sequentially from each mold of one set of two or more molds directly to one of at least two blowing apparatus;
• transferring the preforms while they are still warm sequentially from each mold of each other set of two or more molds directly to each other blowing apparatus, there being a separate blowing apparatus for each set of two or more molds;
• and
• blowing the preforms into plastic articles in each of the blowing apparatus, the time interval between the forming of the preform and the blowing of the preform being substantially the same for all preforms.

A method of making plastic articles, which comprises the steps of:

• extruding a stream of hot plasticized resin;
• providing a plurality of preform molds disposed in at least two sets with each set comprising two or more molds;
• directing the stream sequentially into the preform molds;
• forming a preform in each mold;
• providing a separate blowing apparatus for each set of two or more molds;
• removing the preforms from each mold in one of the sets of molds and transferring them directly to the blowing apparatus for that set of molds before the preforms cool substantially, the preforms being transferred sequentially from each mold of the set;
• blowing the preforms in the blowing apparatus into plastic articles;
• and
• sequentially transferring the preforms from each other set of molds to the respective blowing apparatus for that set of molds, and blowing the preforms into plastic articles.

A method of making plastic articles from a thermoplastic resin material, which comprises the steps of:

• (a) extruding hot plasticized resin continuously;
• (b) feeding the plasticized resin sequentially into a plurality of preform molds disposed in at least two sets of molds, each set of molds comprising two or more molds;
• (c) forming preforms in each mold;
• (d) transferring the preforms while still warm sequentially from each mold of each set of molds to one of at least two blowing apparatus;
• (e) sequentially transferring the preforms from each other set of molds to the respective blowing apparatus for that set of molds;
• (f) temperature conditioning uniformly the preforms in each blowing apparatus;
• (g) stretching and orienting the preforms in each blowing apparatus;
• (h) blowing the preforms into plastic articles in each blowing apparatus, the time interval between steps (c) and (g) being substantially the same for all preforms;
• and
• (i) removing the plastic articles from each blowing apparatus.

A method of making plastic articles from a thermoplastic resin material, which comprises the steps of:

• (a) extruding hot plasticized resin;
• (b) feeding the plasticized resin into a first mold of a set of two or more molds to form a first preform, there being at least two sets of molds;
• (c) transferring the first preform before it cools excessively from the first mold directly to one of a plurality of blowing apparatus;
• (d) after performing step (b), feeding the plasticized resin into a second mold of the set of molds to form a second preform;
• (e) blowing the first preform in the blowing apparatus to form the plastic article;
• (f) removing the plastic article from the blowing apparatus;
• (g) after performing step (c), transferring the second preform before it cools excessively from the second mold directly to the same blowing apparatus used in step (c);
• (h) repeating steps (e) and (f) for said second preform, the time interval between forming and blowing being substantially the same for both the first and second preforms;
• and
• (i) sequentially performing steps (b) through (h) for each other set of molds using the respective blowing apparatus for that set of molds.

A method of making plastic articles from a thermoplastic resin material which comprises the steps of:

• (a) placing plastic resin material in an extruder;
• (b) heating and extruding plasticized resin from the extruder continuously;
• (c) sequentially feeding the plasticized resin into alternate molds of a plurality of molds, the molds being disposed in sets with at least two molds in each set;
• (d) forming a first preform in the first mold of one of the sets;
• (e) substantially immediately after step (d), transferring the first preform while it is warm from the first mold directly to one of a plurality of blowing apparatus units, the number of blowing apparatus units being equal to the number of sets of molds;
• (f) while performing step (e), forming a second preform in the second mold of the set;
• (g) while performing step (d) and substantially immediately after step (f), transferring the second preform from the second mold directly to the same blowing apparatus unit as in step (e);
• (h) receiving the preforms sequentially transferred in steps (e) and (g) in the blowing apparatus unit;
• (i) temperature conditioning the preforms in the blowing apparatus unit;
• (j) blowing the preform in the blowing apparatus units to form the plastic article, the time interval between steps (d) and (i) for the first preform being substantially the same as the time interval between steps (f) and (i) for the second preform;
• (k) removing the plastic article from the blowing apparatus unit;
• and
• (l) performing steps (a) through (k) for each other set of molds using each other of the plurality of blowing apparatus units.