| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method of manufacture of an electric heating mat used in molding of a branched pipe joint burying the electric heating mat mounting an electric heating wire in a reverse surface of an almost semicylindrically curved saddle, so as to prevent a distortion from being left in the electric heating wire when it is wound. SOLUTION: A method of manufacture of an electric heating mat is used in molding of a branched pipe joint burying the electric heating mat mounting an electric heating wire in a reverse surface of an almost semicylindrically curved saddle. A through hole 21 is provided in an almost central part, the method of manufacture comprises a process winding an electric heating wire D along a groove of a metal-made mat 2 providing a spiral groove 22 with this through hole 21 serving as the center, process applying fixed voltage to this electric heating wire D to heat it cooled so as to obtain a spiral electric heating wire 12 removing a distortion at winding time and a process mounting this spiral electric heating wire 12 in a groove of a resin-made mat formed in the same shape to the metal-made mat 2.</p> |
