GB570373A - Improvements in and relating to the treatment of tubing - Google Patents

Abstract

570,373. Liquid treatment of flexible tubing. BRIGGS MANUFACTURING CO. May 4, 1943, No. 7025. Convention date, May 9, 1942. [Class 140] In the treatment of flexible (e.g., fibrous) tubing with a liquid (e.g., resinous) composition, the tubing is passed through the liquid so that this is applied to both the inner and outer surfaces, and is then fed through a doctor device which removes excess liquid from both surfaces and comprises a tube containing an element (e.g., an iron ball) which is magnetically held within the tubing. The inner surface of the doctor tube may make actual contact with the outer surface of the flexible tubing. As shown, apparatus for impregnating a length of fibrous tubing, as of woven wool, cotton, silk, or glass with resinous material, e.g., a phenol-formaldehyde resin, comprises a tank 16, Fig. 1, for the resinous liquid. which may be heated by coils, and through which the tubing 10 is passed over pulleys 18. 20, 21 from a supply roll 11. From the tank the tubing is delivered through a doctor A via curing and cooling stacks 43, 44 and a pulley 34 to a take-up roll 37. The doctor A comprises an open-ended tube 28, Fig. 3, of non-magnetic material such as copper, brass, bronze, or stainless steel, enclosing a ball 27 of magnetic material which rests on a shoulder formed between two sections 29, 30 of the tube having diameters respectively greater than and less than that of the ball ; an intermediate annular casing 42 through which hot oil, water, or steam may be circulated ; and an outer annular casing 25 containing a solenoid which serves both to hold the ball 27 in position within the tubing 10 as this is fed through the tube 28, and also to heat the ball by induction. Using phenol-formaldehyde as the resinous material, the temperatures of the tank 10 and doctor A are maintained around 240‹ F. and 220‹ F. respectively. In the curing stack 43 the temperature is maintained at about 300‹ F. to cause polymerization of the resin. Various other shapes of the magnetic element 27 are referred to. Reference is made to a similar known treatment in which the magnetic element operates without the external doctor tube.