Method of making electrical heating units

Claim 1

A method of making an electrical heating unit such method comprising, A. providing a strip of undulated electrical resistance wire, B. shaping said strip of wire into a planar or areal configuration or pattern desired for a heating element for said heating unit; C. disposing in contact with one of the planar surfaces of said shaped strip of wire a planar surface of a masking member, such surface having a configuration or pattern corresponding to said one planar surface of said strip of wire but of lesser dimensions in width than the width of such wire strip; D. disposing the assembly, comprising said wire strip and said masking member, adjacent the bottom of a mold member having a cavity corresponding in planar configuration to the outer reaches of said shaped wire strip but of somewhat larger dimensions than said outer reaches, said assembly being so disposed with said masking member contacting said bottom of said mold member; E. flowing a mixture of an insulating and hardenable material into said mold member to encapsulate and cover said assembly to a depth for a desired insulating support for said heating unit; F. drying and hardening said mixture of insulating material; G. removing said encapsulated assembly from said mold member following the hardening of said encapsulating material; and H. removing said masking member from said encapsulated assembly to thereby expose the portion of said one planar surface of said shaped strip of wire contacted by the masking member while leaving the undulations along the edges of such wire strip embedded in said encapsulating and insulating material, whereby said electrical heating unit results.

Claim 2

A method of making an electrical heating unit such method comprising, A. providing a strip of undulated electrical resistance wire, B. shaping said strip of wire into a planar or areal configuration or pattern desired for a heating element for said heating unit; C. disposing in contact with one of the planar surfaces of said shaped strip of wire a planar surface of a masking member, such surface having a configuration or pattern corresponding to said one planar surface of said strip of wire but of lesser dimensions in width than the width of such wire strip; D. disposing the assembly, comprising said wire strip and said masking member, adjacent the bottom of a mold member having a cavity corresponding in planar configuration to the outer reaches of said shaped wire strip but of somewhat larger dimensions than said outer reaches, said assembly being so disposed with said masking member contacting said bottom of said mold member; E. flowing a mixture of an insulating and hardenable material into said mold member to encapsulate and cover said assembly to a depth for a desired insulating support for said heating unit; F. drying and hardening said mixture of insulating material; G. removing said encapsulated assembly from said mold member following the hardening of said encapsulating material; and H. removing said masking member from said encapsulated assembly to thereby expose the portion of said one planar surface of said shaped strip of wire contacted by the masking member while leaving the undulations along the edges of such wire strip embedded in said encapsulating and insulating material, whereby said electrical heating unit results.