Method and apparatus for attaching insulation to duct work

Claim 1

The method of attaching an insulator batt or the like to a metal substrate, comprising the steps of providing a welding pin having an elongated shank with a turned, sharpened tip tapering to a point at one end and an enlarged head having an area of at least about 20 times the shank cross section at the other end, advancing said pin, point first, through said batt and into pressured contact with said substrate, passing a welding current through the length of said pin to melt said tip while maintaining said head in intimate contact with an electrode defining a heat sink, and while continuously pressing said tip against said substrate, thereby to melt said tip to effect a weld to said substrate while simultaneously cooling said head and the head adjacent portions of said shank to maintain a temperature differential of at least about 1,500* F. between said tip of said pin and the portions of said shank adjacent said head, whereby the electrical resistance of increments of said shank adjacent said tip, after commencement of said weld, greatly exceed the electrical resistance of portions of said shank adjacent said head.

Claim 2

The method of attaching an insulator batt or the like to a metal substrate, comprising the steps of providing a welding pin having an elongated shank with a turned, sharpened tip tapering to a point at one end and an enlarged head having an area of at least about 20 times the shank cross section at the other end, advancing said pin, point first, through said batt and into pressured contact with said substrate, passing a welding current through the length of said pin to melt said tip while maintaining said head in intimate contact with an electrode defining a heat sink, and while continuously pressing said tip against said substrate, thereby to melt said tip to effect a weld to said substrate while simultaneously cooling said head and the head adjacent portions of said shank to maintain a temperature differential of at least about 1,500* F. between said tip of said pin and the portions of said shank adjacent said head, whereby the electrical resistance of increments of said shank adjacent said tip, after commencement of said weld, greatly exceed the electrical resistance of portions of said shank adjacent said head.

Claim 3

The method of attaching an insulative batt or the like to a metal substrate, such as a duct, by resistance welding through the use of an elongated pin having a head portion, the cross-sectional area of which is at least about 20 times the cross-sectional area of the shank of said pin, said pin having a tapered, turned, sharpened tip, which comprises the steps of intimately contacting said head portion with an electrode which also comprises a heat sink, pressing said pointed tip against said substrate and passing a current from said electrode through the length of said pin into said duct while continuing said pressure of said tip against said substrate to melt said tip portion while said head of said pin is maintained in intimate contact with said heat sink electrode, thereby to establish a high-temperature gradient along the length of said pin and divide said pin into high resistance areas adjacent said duct and low resistance areas adjacent said head.

Claim 4

The method of attaching an insulative batt or the like to a metal substrate, such as a duct, by resistance welding through the use of an elongated pin having a head portion, the cross-sectional area of which is at least about 20 times the cross-sectional area of the shank of said pin, said pin having a tapered, turned, sharpened tip, which comprises the steps of intimately contacting said head portion with an electrode which also comprises a heat sink, pressing said pointed tip against said substrate and passing a current from said electrode through the length of said pin into said duct while continuing said pressure of said tip against said substrate to melt said tip portion while said head of said pin is maintained in intimate contact with said heat sink electrode, thereby to establish a high-temperature gradient along the length of said pin and divide said pin into high resistance areas adjacent said duct and low resistance areas adjacent said head.

Claim 6

The method of attaching an insulative batt comprising a material subject to disintegration under intense heat to a metallic duct by resistance welding, comprising the steps of providing a conductive welding pin including an elongated shank having a sharpened, turned tip at one end and an enlarged head at the other, contacting said head with a first electrode defining a heat sink, contacting said duct with the other electrode, advancing said pin, tip end first, through said insulating batt to bring said tip into conductive contact with said duct, and passing a welding current through said head and shank while continuously pressing said tip against said duct, thereby to effect a resistance weld between said tip portion of said pin and said duct while simultaneously cooling said head and the head adjacent portions of said shank of said pin by the contact of said head and said first electrode, thereby to prevent overheating of said pin in the areas of said shank adjacent said head to avoid heat damage to the portion of said batt juxtaposed to said head adjacent portions.

Claim 7

The method of attaching an insulative batt comprising a material subject to disintegration under intense heat to a metallic duct by resistance welding, comprising the steps of providing a conductive welding pin including an elongated shank having a sharpened, turned tip at one end and an enlarged head at the other, contacting said head with a first electrode defining a heat sink, contacting said duct with the other electrode, advancing said pin, tip end first, through said insulating batt to bring said tip into conductive contact with said duct, and passing a welding current through said head and shank while continuously pressing said tip against said duct, thereby to effect a resistance weld between said tip portion of said pin and said duct while simultaneously cooling said head and the head adjacent portions of said shank of said pin by the contact of said head and said first electrode, thereby to prevent overheating of said pin in the areas of said shank adjacent said head to avoid heat damage to the portion of said batt juxtaposed to said head adjacent portions.