Patent ID: 8057631

Claim:
A method for applying strips of thermoplastic material to thermoplastic membranes, the strips each having an upstanding central portion extending lengthwise thereof and opposed flange portions extending widthwise from a base of the central portion, the method comprising the steps of: applying a first thermoplastic strip to a thermoplastic membrane; providing apparatus comprising: a self-propelled housing assembly having drive wheels thereon for movably supporting said housing on the membranes; a guide assembly fixed to said housing assembly, said guide assembly comprising: a first pair of guide wheels for disposition around the previously applied first strip, and movable along the first strip with one guide wheel on either side thereof; and a second pair of guide wheels for disposition around a second strip to be applied, and movable along the second strip so as to guide the second strip to a welding station mounted on the apparatus, the welding station being adapted to heat weld the second strip to at least one of the membranes; mounting the first pair of guide wheels on the first strip; mounting the second pair of guide wheels on the second strip; and moving the housing on the drive wheels, the first pair of guide wheels riding along the first strip and the second pair of guide wheels channeling the second strip therebetween and into the welding station for attachment to the membrane by the heat weld, the second strip thereby extending equidistantly from the first strip.