Method of making a high temperature flexible unitary sleeving insulation
AssigneeEssex Group, Inc.
InventorsLouis G. Landry, Fabian Nunez
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Abstract
The present invention discloses a glass covered electrical insulation having an inner lining of glass fibers coated with a flexible, high temperature, electrically insulating silicone polymer, the electrically insulating layer then has a second layer of glass fibers overbraided on it and bonded to it by the use of a heat treating process. A further teaching is the method of making the flexible sleeving and a method of use. The sleeving is particularly adapted for use in VPI processing and has superior flexibility as well as higher temperature capabilities than sleeving of the prior art.
Claims1
A method of making a flexible, unitary electrical insulation sleeving comprising, in combination, the steps of:
- (a) drawing a fiberglass sleeving through a heat source to heat stabilize the fiberglass sleeving;
- (b) coating the heat stabilized fiberglass sleeving with a silicone rubber having a Shore A durometer hardness of 40 or lower in a die operating at a pressure greater than atmospheric, thereby bonding the silicon rubber to the fiberglass sleeving;
- (c) heating the coated fiberglass sleeving formed in step (b) in a curing oven heated to a temperature of about 400.degree. F. (204.degree. C.) to about 500.degree. F. (260.degree. C.) to cure the silicone rubber;
- (d) introducing a gas into one end of the coated fiberglass sleeving to create a positive pressure of from about 1 to about 5 psig within the sleeving;
- (e) overbraiding the pressurized coated fiberglass sleeving with fiberglass having about 10 to about 20 pics to the inch without adding an adhesive to the silicon rubber;
- (f) drawing the overbraided coated fiberglass sleeving formed in step (e) through a die and then through a furnace heated to a temperature of about 1,000.degree. F. (537.8.degree. C.) without adding an adhesive to the overbraid;
- and
- (g) heating the overbraided coated fiberglass sleeving in the furnace to a temperature sufficient to bond the overbraid directly to the silicon rubber, thereby forming a unitary highly flexible, electrically insulated sleeving with high dielectrics strength.
Dependencies are inferred from the claim text.