PURPOSE: To obtain the titled tube having no constriction or locally varied thickness and useful as a corrosion preventive layer or the like for an electric power cable connection part, by placing a raw tube coaxially in a molding pipe, heating them with the opposite ends sealed, and expanding molding the raw tube using compressed air by a special method.
CONSTITUTION: A raw tube (for example: of vinyl chrolide, etc.) 2 is placed coaxially in a molding pipe 1 having an inner diameter equal to the outer diameter of the intended heat shrinkable tube, the opposite ends of the raw tube 2 and the molding pipe 1 are dismountably secured to caps 5, 6 or the like, are sealed, and then are heated. Pressurized fluid is filled from a fluid supply hose 8 into the space between the raw tube 2 and the molding pipe 1, and the pressurised fluid in the space is gradually evacuated through a discharge hose 9 to reduce the pressure in the space 13 while compressed air is charged vai an air hose connected to an open plug 3 at the upper end of the raw tube 2 into the raw tube 2 until the raw tube becomes in contact with the inner wall of the molding pipe so that the raw tube is expanded to be molded.
KATOU MASAHIRO
OOTA MINORU
SHIRAIWA MASAICHI
