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Method and apparatus for making a continuous length of tubing having an annular wall formed of polyurethane, including a forming cylinder having a mandrel extending centrally therethrough. Two strips of paper material are pulled through the forming cylinder, one surrounding the mandrel and one being

Method and apparatus for making a continuous length of tubing having an annular wall formed of polyurethane, including a forming cylinder having a mandrel extending centrally therethrough. Two strips of paper material are pulled through the forming cylinder, one surrounding the mandrel and one being disposed at the interior surface of the cylinder, and a curable plastic mixture is injected into the annular space between the paper strips. A sensor is provided to determine the point at which curing of the plastic mixture begins in the annular spacing within the cylinder, and the speed of travel of the paper through the cylinder is regulated as a function thereof. The control system shuts the apparatus down if a break in the paper strips is detected, or if the paper supply approaches exhaustion, or if the point of full curing is within a predetermined minimum spacing from the inlet end of the cylinder. Protrusions are provided at the outlet end of the cylinder to score the outer paper layer of the tubing, and the cylinder is mounted to frame for easy removal therefrom whereby cylinders of various sizes can be used.

대표청구항 ▼

Apparatus for making a continuous length of tubing with walls formed of foamed material, said apparatus comprising: a. a forming cylinder having mandrel means extending centrally along the length of said cylinder; b. first means for feeding a first strip of flexible material into one end of and thro

Apparatus for making a continuous length of tubing with walls formed of foamed material, said apparatus comprising: a. a forming cylinder having mandrel means extending centrally along the length of said cylinder; b. first means for feeding a first strip of flexible material into one end of and through said forming cylinder, and forming said first strip of material into a cylindrical shape about said mandrel; c. second means for feeding a second strip of flexible material into said one end of and through said forming cylinder, and forming said first strip of material into a cylindrical shape at the interior surface of said forming cylinder; d. means for injecting a curable foaming plastic mixture into said one end of said forming cylinder and into the annular space between said first and second strips of flexible material; and e. control means comprising a sensor means disposed adjacent said one end of said forming cylinder for sensing the point along the length of said forming cylinder at which said foaming plastic mixture begins to cure into a solid across the cross-section of said annular space between said strips of material, and regulating means responsive to said sensing means for selectively varying the speed at which said first and second strips of flexible material are fed through said forming cylinder.