GB894657A - Thread-end holder for sewing machines - Google Patents

Abstract

894,657. Sewing-machines. SINGER MANUFACTURING CO. May 15, 1959 [May 26, 1958], No. 16711/59. Class 112. Thread end holders, using the movement of air. A thread end holder for securing the loose ends of the sewing threads during the initial operation of the stitching mechanism of a sewing-machine comprises a rod 27 carried on the machine head 5 for endwise movement thereon, a clamping foot 41 mounted on the rod for movement into and out of engagement with the work supporting surface of the machine, and fluid pressure means for imparting endwise movement to the rod. The rod 27 which comprises two parts 26 and 29 is mounted for endwise sliding in a bushing 28 in the head of a cylinder 20 and in a bracket 30 mounted on a plate 17 secured to the head 5. A piston 25 within the cylinder is mounted on the part 26 of the rod and biased upwards by a spring 36. An arm 34 mounted on a collar 33 on the piston rod projects through a slot 35 in the plate to restrain the rod from turning. Compressed air is supplied to the top of the cylinder from a solenoid actuated valve unit 38. The thread clamping foot 41 has a horizontal stud mounted in a bore in a shank 43 secured to the lower part 29 of the rod 27, the foot 41 being free to turn about the horizontal axis of the stud to provide automatic levelling relative to the throat plate 12. The turning of the foot is limited by a pin mounted on the stud, which is received in a groove in the shank, (Fig. 4, not shown). To position the thread ends beneath the clamping foot a blower is provided comprising a bore or nozzle 50 in the throat plate positioned to blow the threads beneath the foot in a direction slightly forward of the direction of feed and connected to a source of compressed air. Before the operation of the sewing machine is commenced the thread ends are blown under the foot, the solenoid of the valve unit 38 is energized to supply air to above the piston and-the foot is forced downwards to clamp the thread ends against a roughened surface of the throat plate. After the formation of a few stitches the solenoid is de-energized and the spring 36 raises the piston and the clamping foot. Releasing thread tension. To prevent breakage of the needle thread while clamped by the foot when there is insufficient thread in the thread system to accommodate the take-up action an arm 53 pivoted to a bracket 54 has one end engaged by the collar 33 on the piston rod when the clamping foot is lowered. The other end of the arm 53, which extends round the head 5, then engages and releases the needle thread tension device. The presser foot has a sole plate 15<SP>1</SP> mounted for rotation about an axis coinciding with the axis of a needle aperture in the foot, so that the plate 15<SP>1</SP> will remain in line with or tangential to the line of seam formation as the work is moved in straight lines or around corners respectively. The throat plate has a needle aperture 13 and is provided with a roughened surface in the area engaged by the foot 41.