GB141888A - Work-holder mechanisms for buttonhole sewing machines - Google Patents

Abstract

141,888. Fairweather, W., (Singer Manufacturing Co.). April 5, 1919. Button-hole sewing-machines.-A work-clamp. made in two parts so that the work can be spread after it is clamped, is provided with two separately adjustable spreading-devices so that the ends of the button-hole can be stretched to different extents. The stretching-cams are not themselves adjustable, but the plates on the clamp-parts are adjustable to or from the cams, so as to vary the lost motion. The lower clamping-plates 11 upon which the upper clamping- plates are mounted can move, under the restraint of screws 25, laterally between guides 10, 24 and can rotate slightly. A pin 35 having a head with two flats is placed between plates 38 on the plate 11 and, when rotated, separates the plates 38. The pin 35 carries an arm 34 linked by a dumbbell shaped part 33 to a plate 32 having cam-projections 31, and when the pin is rotated, these projections bear upon pins 29 and separate the inner ends of the clamp-plates 11. By adjusting the plates 38 and plates 26 which carry the pins 29, any desired differential stretching may be given to the button-hole. The pin 35 is rotated to stretch the work during the withdrawal of the cutting-devices, by means of a rack-rod 50, a latch lever 47, and a lever arm 45 on the pin 35. The pin is then locked by a detent lever 58; the latch-lever 55 also serves to hold it. At the close of the stitching operation, the feed-wheel, by means of a lever 63, turns the detent lever 58, thereby removing the lock on the arm 46 of the pin 35, and also, by an arm 60, depressing the hinged latch lever 47. This permits the pin 35 to turn, under the influence of a spring 43, and the lateral tension is removed from the fabric.