Sealing jaw constructed from two ceramic materials of which one is electrically conductive
AssigneeTetra Laval Holdings & Finance S.A.
InventorHans Selberg
Life of this patent
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Abstract
The invention relates to a sealing jaw for sealing thermoplastic materials or paper or cardboard coated with thermoplastic material, preferably packaging material. The sealing jaw is constructed from two ceramic materials, of which one is electrically insulating and the other electrically conductive: The electrically conductive ceramic material forms a continuous strand embedded in the insulating material and is, at or in the proximity of its end points, metallized so as to make good connection with an electric current source. The electrically conductive ceramic materials are treated with high pressure and heat so that they together form a pore-free, hard and abrasion-resistant body which can be applied to a steel rail.
Claims18
A method for making a sealing jaw adapted to seal thermoplastic materials, said sealing jaw having an electrically insulating ceramic layer a heating element, which is imbedded in said insulating layer, first connecting means, which is located in proximity to one end of said heating element, and second connecting means, which is located in proximity to an opposite end of said heating element, said first and second connecting means connecting said heating element to a source of electric current, and said heating element being made from an electrically conductive ceramic material and cooperating with said first and second connecting means to form an electric current conducting pathway, whereby electric current flowing through said heating element causes the direct heating of said heating element, said method comprising the steps of forming ceramic powders into bodies of desired configuration for said insulating layer and said heating element;
- uniting said bodies with one another into a combined body;
- heating said combined body to a range between 1600.degree. C. and 1900.degree. C. under a pressure exceeding 100 MPa for at least 120 minutes, whereby the ceramic powders are sintered together to form an integral, dense and pore-free structure which is extremely hard and abrasion-resistant.
Apparatus adapted for use in producing packages which are formed from a tube produced from a planar web of packaging material, the tube being, after filling with the intended contents, divided up into packaging containers by repeated sealings transversely of the longitudinal direction of the tube, said apparatus comprising a sealing jaw having an electrically insulating ceramic layer a heating element, which is imbedded in said insulating layer such that at least a portion of said heating element is inlaid in said insulating layer, said at least a portion of said heating element and said insulating layer being sintered together so as to form an integral, fine-pored, hard and abrasion-resistant body;
- first connecting means, which is located in proximity to one end of said heating element;
- and second connecting means, which is located in proximity to an opposite end of said heating element, said first and second connecting means connecting said heating element to a source of electric current, and said heating element being made from an electrically conductive ceramic material and cooperating with said first and second connecting means to form an electric current conducting pathway, whereby electric current flowing through said heating element causes the direct heating of said heating element.
A sealing jaw for sealing thermoplastic materials, comprising an electrically insulating ceramic layer;
- a heating element imbedded in said insulating layer such that at least a portion of said heating element is inlaid in said insulating layer, said at least a portion of said heating element and said insulating layer being sintered together so as to form an integral, fine-pored, hard and abrasion-resistant body;
- first connecting means located in proximity to one end of said heating element;
- and second connecting means located in proximity to an opposite end of said heating element, said first and second connecting means connecting said heating element to a source of electric current, and said heating element being made from an electrically conductive ceramic material and cooperating with said first and second connecting means to form an electric current conducting pathway, whereby electric current flowing through said heating element causes the direct heating of said heating element.
Dependencies are inferred from the claim text.