Blow molding method and apparatus
AssigneeELC Management LLC
InventorSushil Iyer
Life of this patent
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Abstract
In a method of forming a container from a thermoplastic material, a thermoplastic preform may be introduced into a blow cavity at a temperature greater than or equal to a glass transition temperature of a thermoplastic material and less than a melting temperature of the thermoplastic material. A fluid pressure may be introduced into a preform that may expand the preform radially outwardly to form a semi-finished container. An external surface of the semi-finished container may be engaged with a wall of the blow cavity. The wall of the blow cavity may be rapidly heated. Heat may be transferred to the external surface of the semi-finished container. A surface finish may be imparted from the wall of the blow cavity onto the external surface of the semi-finished container.
Claims15
A method of forming a container from a thermoplastic material, comprising the steps of:
- introducing a thermoplastic preform into a blow cavity at a temperature greater than or equal to a glass transition temperature of the thermoplastic preform and less than a melting temperature of the thermoplastic preform;
- introducing a fluid pressure into the preform to expand the preform radially outwardly to form a semi-finished container;
- engaging an external surface of the semi-finished container with a wall of the blow cavity;
- heating the wall of the blow cavity;
- transferring heat to the external surface of the semi-finished container;
- imparting a surface finish from the wall of the blow cavity onto the external surface of the semi-finished container;
- and
- arranging one or more electrical inductors within a mold body and spacing portions of the one or more electrical inductors equally about a circumference of the blow cavity.
A thermoplastic blow molding apparatus comprising:
- a mold comprising a mold body and a concave blow cavity formed therein;
- one or more electrical inductors within the mold body;
- a source of an alternating current connected across the inductor wherein a frequency of the alternating current is between 10 kHz and 300 kHz,
- wherein the mold is produced from a magnetic material,
- wherein the magnetic material is a tool steel,
- wherein an electrical inductor of the one or more electrical inductors is located within the cooling passage,
- wherein an annular space is formed within the cooling passage about the electrical inductor, and
- wherein the one or more electrical inductors include portions spaced equally about a circumference of the concave blow cavity.
A thermoplastic blow molding apparatus comprising:
- a mold comprising a mold body and a concave blow cavity formed therein;
- one or more electrical inductors within the mold body;
- a source of an alternating current connected across the inductor wherein a frequency of the alternating current is between 10 kHz and 300 kHz,
- wherein an electrical inductor of the one or more electrical inductors is located within or surrounded by the cooling passage, and
- wherein the one or more electrical inductors include portions spaced equally about a circumference of the concave blow cavity.
Dependencies are inferred from the claim text.