US 4,285,657 AGranted

Injection blow molding apparatus

OwnerLeonard B. Ryderinventor

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Abstract

Molecular biaxially oriented hollow articles are obtained by injection blow molding using a novel apparatus. The technique involves the use of an inline, single stage injection blow molding apparatus wherein injection molding and cooling, and conditioning and stretch blow molding of parisons are all performed simultaneously at a single station at different positions within that station.

Claims9

Dependent claims

An apparatus for forming biaxially oriented articles from thermoplastic materials, said apparatus comprising:

(a) at least one injection mold defining an injection mold cavity having an open mouth and a horizontal longitudinal axis;
(b) two blow molds associated with and positioned laterally of each injection mold, each such blow mold defining a blow mold cavity having an open mouth and a horizontal longitudinal axis, the dimensions of each such blow mold cavity being greater than the dimensions of said injection mold cavity;
(c) two core assemblies corresponding to each injection mold and its associated blow molds, each such assembly including an elongated core rod having a horizontal longitudinal axis and a sleeve surrounding such core rod in the neck area, said sleeves and core rods having respective circumferentially extensive seal surfaces, each such core rod having a parison contact portion which extends outwardly to a parison contact end or tip, each such core rod being slidable relative to the associated sleeve, between a fully retracted position wherein its seal surface sealingly engages the seal surface of the associated sleeve and a fully extended position wherein its seal surface is spaced from the seal surface of the associated sleeve in an outward direction;
(d) support and transfer means, consisting of conventional injection molding machine platens, press, and lateral shifting mechanism for engaging and disengaging each of said core assemblies alternately with an injection mold and a blow mold, such that the sleeve of the core assembly is within the cavity mouth of the engaged mold and the core rod of the core assembly protrudes into the cavity of said mold, said support and transfer means being constructed and arranged to simultaneously engage one of said core assemblies with an injection mold and one of said core assemblies with a blow mold;
(e) neck form means, operative during the engagement of each of said core assemblies within an aforesaid mold, for defining the neck extension of the mold cavity and for retaining a parison about the core rod;
(f) core rod retractor means for retaining the core rod of each of said core assemblies in its fully retracted position while such assembly is engaged within an injection mold, and holding the core rod in this position during lateral transfer to a blow mold until the time the core rod is advanced for axial stretching;
(g) injection means comprising sprues in the injection mold which allow thermoplastic, in molten form, to be injected via a conventional runner system, into the cavity of each of the said injection molds while one of said core assemblies is engaged therewith to form a parison;
(h) core rod cooling means comprising interlaced helical channels formed around a cylindrical flow director slug within the core rod wherein coolant is circulated throughout the core rod for maintaining parison contact surfaces of said core rod at cold temperatures relative to the injection temperatures at which the thermoplastic is processed, at least while such core rod is engaged within the injection mold;
(i) injection and blow mold cooling means for maintaining the cavity surface of each said injection and blow molds at cold temperatures relative to the injection temperatures of the thermoplastic being processed;
(j) equilibration means for promoting equalization of temperatures across the wall thickness of a parison during the interval between the engagement of the associated core rod within the blow mold and the advancement of the core rod of such assembly during axial stretching of the parison;
(k) core rod advance means for advancing the core rod of each of said core assemblies to a partially or fully extended position during each engagement of said core assemblies within a blow mold, so that an associated parison thereon may be stretched in an axial direction;
(l) blow gas passageway means for introducing gas under pressure within each parison while said parison is within a blow mold cavity, at a time not earlier than the aforesaid axial stretching of such parison, to radially expand and stretch the walls of such parison into intimate contact with the blow mold cavity surfaces, such that said parison assumes the final shape of a finished article;
(m) final cooling means for cooling each of said finished articles to a suitable ejection temperature within a blow mold cavity;
and
(n) means for releasing each finished article from its associated neck form means and for ejecting said finished article from its associated core assembly while said core assemblies are disengaged from said injection mold and blow molds.

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Dependencies are inferred from the claim text.

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Abstract

An apparatus for forming biaxially oriented articles from thermoplastic materials, said apparatus comprising:

(a) at least one injection mold defining an injection mold cavity having an open mouth and a horizontal longitudinal axis;
(b) two blow molds associated with and positioned laterally of each injection mold, each such blow mold defining a blow mold cavity having an open mouth and a horizontal longitudinal axis, the dimensions of each such blow mold cavity being greater than the dimensions of said injection mold cavity;
(c) two core assemblies corresponding to each injection mold and its associated blow molds, each such assembly including an elongated core rod having a horizontal longitudinal axis and a sleeve surrounding such core rod in the neck area, said sleeves and core rods having respective circumferentially extensive seal surfaces, each such core rod having a parison contact portion which extends outwardly to a parison contact end or tip, each such core rod being slidable relative to the associated sleeve, between a fully retracted position wherein its seal surface sealingly engages the seal surface of the associated sleeve and a fully extended position wherein its seal surface is spaced from the seal surface of the associated sleeve in an outward direction;
(d) support and transfer means, consisting of conventional injection molding machine platens, press, and lateral shifting mechanism for engaging and disengaging each of said core assemblies alternately with an injection mold and a blow mold, such that the sleeve of the core assembly is within the cavity mouth of the engaged mold and the core rod of the core assembly protrudes into the cavity of said mold, said support and transfer means being constructed and arranged to simultaneously engage one of said core assemblies with an injection mold and one of said core assemblies with a blow mold;
(e) neck form means, operative during the engagement of each of said core assemblies within an aforesaid mold, for defining the neck extension of the mold cavity and for retaining a parison about the core rod;
(f) core rod retractor means for retaining the core rod of each of said core assemblies in its fully retracted position while such assembly is engaged within an injection mold, and holding the core rod in this position during lateral transfer to a blow mold until the time the core rod is advanced for axial stretching;
(g) injection means comprising sprues in the injection mold which allow thermoplastic, in molten form, to be injected via a conventional runner system, into the cavity of each of the said injection molds while one of said core assemblies is engaged therewith to form a parison;
(h) core rod cooling means comprising interlaced helical channels formed around a cylindrical flow director slug within the core rod wherein coolant is circulated throughout the core rod for maintaining parison contact surfaces of said core rod at cold temperatures relative to the injection temperatures at which the thermoplastic is processed, at least while such core rod is engaged within the injection mold;
(i) injection and blow mold cooling means for maintaining the cavity surface of each said injection and blow molds at cold temperatures relative to the injection temperatures of the thermoplastic being processed;
(j) equilibration means for promoting equalization of temperatures across the wall thickness of a parison during the interval between the engagement of the associated core rod within the blow mold and the advancement of the core rod of such assembly during axial stretching of the parison;
(k) core rod advance means for advancing the core rod of each of said core assemblies to a partially or fully extended position during each engagement of said core assemblies within a blow mold, so that an associated parison thereon may be stretched in an axial direction;
(l) blow gas passageway means for introducing gas under pressure within each parison while said parison is within a blow mold cavity, at a time not earlier than the aforesaid axial stretching of such parison, to radially expand and stretch the walls of such parison into intimate contact with the blow mold cavity surfaces, such that said parison assumes the final shape of a finished article;
(m) final cooling means for cooling each of said finished articles to a suitable ejection temperature within a blow mold cavity;
and
(n) means for releasing each finished article from its associated neck form means and for ejecting said finished article from its associated core assembly while said core assemblies are disengaged from said injection mold and blow molds.

12 more elements