Patent ID: 6942752

Claim:
A method for joining, to each other, a first edge of a first thermoplastic sheet and a second edge of a second thermoplastic sheet, the method comprising acts of forming substantially matching angles on the first edge of the first thermoplastic sheet and on the second edge of the second thermoplastic sheet such that the first and second edges are inclined with respect to an upper surface of the first and second thermoplastic sheets, respectively, thereby forming first and second matching inclined edges; forming openings in the first edge of the first thermoplastic sheet, the openings extending transversely from the first edge into the first thermoplastic sheet; forming openings in the second edge of the second thermoplastic sheet, the openings extending transversely from the second edge into the second thermoplastic sheet; placing the first and second matching inclined edges together with a slight overlap such that the substantially matching inclined edges fit together; pressing the first and second matching inclined edges together; heating the first and second matching inclined edges to above a melting temperature of the thermoplastic sheets; maintaining contact between the first and second matching inclined edges for a predetermined period of time; cooling the first and second matching inclined edges, so that they are joined together; and wherein the openings extend substantially beyond a heated zone of the first and second matching inclined edges created by the heating act.