Provision of plastic insulation upon an electrical conductor

Abstract From the Canadian patent

Abstract of the Disclosure, Providing plastic insulation on an electrical conductor in which the conductor, enclosed in an oversize tube is passed through a, fluid and through an annular crystal of a piezoelectric material immersed in the fluid. During passage of tube and conductor the crystal is, subjected to electric current to cause alternating expansion and contraction of the crystal. Pressure shockwaves are produced by this expansion and contraction and the shockwaves are focussed upon the pass line of the tube and conductor to cause localized inward deformations of the tube into engagement with the conductor to form spaced annular depressions in the tube. In preferred arrangements …