GB1087900A - A process and apparatus for the heat treatment of yarn - Google Patents

Abstract

1,087,900. Heat-treating yarns. ALLIED CHEMICAL CORPORATION. Dec. 22, 1965 [Dec. 23, 1964], No. 54411/65. Heading B5B. Apparatus for heat-treating at controlled length a molecularly oriented, thermoplastic, heatshrinkable yarn 1, comprises a draw roll 5, a heater 10 having a substantially triangular cross - section, two of its sides respectively, 8 and 9, comprising a primary and a secondary outwardly arched heating surface, the third side being nearest the draw roll, a separator roll 7, an idler roll 6, and means 2 for feeding yarn to surface 8 and withdrawing it from draw roll 5 after it has been passed as a plurality of wraps about the heater and draw roll, the heating surfaces and one end portion of the draw roll being given matte low-friction surfaces, the arrangement being such that the common tangents between the guide roll and separator roll, and between the draw roll and separator roll, respectively intersect surfaces 9 and 8 to define arcs on these surfaces between 5 and 25 degrees, no edge of a heating surface being capable of deflecting a yarn wrap through more than 10 degrees, the idler roll and separator roll being each arranged to contact a yarn wrap through at least 10 degrees, and means for withdrawing the yarn under a tension of 0À05-0À25 gpd. at a speed of at least 1500 fpm. In operation, at least one full wrap of yarn contacts the draw roll on a polished surface thereof, and at least the last full wrap contacts it on its matte surface; the coefficient of friction between the yarn and the rolls 7 and 6 being not more than 0À1, and the frictional drag of the yarn over the heated surfaces not exceeding 0À1 gpd. Specified yarns are polyamides, linear polyesters and poly defines.