GB1064904A - Strand monitoring process and apparatus and melt spinning plant using such process - Google Patents

Abstract

A device for monitoring the diameter of a running yarn (particularly in melt-spinning), comprises a gauge responsive to a predetermined minimum variation in the diameter of the yarn, a deflector activated by the gauge for changing the path of the yarn and means for severing the yarn when deflected from its path by the deflector. As depicted in Fig. 2 (not shown) a monitoring device according to the invention mounted on a fixed supporting plate 2 and disposed below the quenching chamber of a melt spinning apparatus comprises a shaft 6 rotatably mounted in the plate 2. A gauge 8 is mounted on the shaft 6 and is adapted to rotate the shaft by downward movement. The gauge consists of a plate 10, one end of which is attached to the shaft 6 and which is provided with a U-shaped slot 14 lined with a pair of gauge bars 16 made of an abrasion-resistant material. A slot 14a between the gauge bars 16 is set to correspond to the predetermined maximum filament diameter intended to pass through the gauge 8 without being detected thereby. The open ends of the slots 14 and 14a are partially enclosed by a crescent-shaped knife blade 18. A pair of bushings 24, rotatably mounted on trunnions 22 projecting from the plate 10 carry rods 26 supporting a deflector 28, which has a concave surface made of a material having a high coefficient of friction. A support bracket 30 welded to the rods 26 limits the counter-clockwise rotation of the rods 26 to a position only slightly off vertical when the gauge 8 is in its normal horizontal position. A counterweight 34 attached to the end of a rod 32 adjustably fixed to the shaft 6 tends to rotate the rod 32 against a limiting pin 36 attached to the plate 2, thus holding the gauge horizontal when spinning conditions are normal. As long as the diameter of the filaments does not exceed a predetermined value they pass freely through the slot 14a of the gauge 8 in the downward direction shown by the arrow, the gauge 8 remains in the horizontal position shown in Fig. 2. When an enlarged diameter portion of one or more of the running filaments reaches the gauge 8, if the diameter is larger than the width of the slot 14a, the further passage of the filaments through the p gauge is prevented, and as the wind-up roll of the melt-spinning apparatus continues to pull the filaments, the gauge 8 will pivot in the clockwise direction about the shaft 6 against the torque of the counterweight 34 and the filament deflector 28 is carried against the filament bundle and pivots downward, about the trunnions 22, as depicted in Fig. 4 (not shown). The deflector 28 bears against the filaments, snubbing them and carrying them against knife edge 18 where the filaments are severed. The deflector 28 besides serving to snub the filaments for severance may also serve to deflect the filaments from their normally vertical downward path to wind upon a godet roll disposed slightly above the deflector and through the plane of rotation of the deflector. Continuous take-up of freshly formed filaments is thus maintained and winding of defective yarn on the wind-up roll of the spinning apparatus is prevented.