GB183586A - Chain-stitch sewing machine - Google Patents

Abstract

183,586. Fairweather, W., (Singer Manufacturing Co.). April 27, 1921. Sewing-machines; thread end-holders and thread cutters; governing needle thread.-A sewing-machine of the kind producing groups of stitches as employed in button-attaching, tacking, &c., and of the type employing a rotary looper for a single-thread chain-stitch is provided with a thread nipper on the supply side of the needle and with a second thread nipper weaker than the first arranged beneath the work rest which is inactive while the needle performs the first reciprocation of a set, the free end of the thread being at the same time drawn beneath the work by the looper, but is then moved automatically to retain the free end during the second reciprocation of the needle. The nipperarm 23, shown as mounted below the work-plate 19 of a machine for button-attaching provided with means for jogging the work-support, is actuated by a link 38 connected to an arm 37 mounted on a rock-shaft 33 rocked by a doublearmed lever 34 engaging cam-plates 29 on the periphery of the cam-wheel 16. The nipper is in contact with an adjustable spring 26 and nips the thread against the plate at the side of the needle-throat. The cam-plates are so arranged that the arm 36 of the lever 34 is in contact with the part e of a cam-plate at the commencement of a group of stitches and as the needle descends the arm is moved by the cam to ensure the retention out of action of the nipper until the needle has made the first stitch. The loose end of thread is at the same time drawn through the work by the looper. As the needle is half-way down on its second stroke the arm 36 rides down the surface d of the cam and the arm 35 rides up the surface b. The nipper is moved into nipping position and yieldingly retains the thread until the commencement of the third stroke, whereupon the arm 35 rides down the surface a and the arm 36 up the surface c and the nipper is moved out of action and withheld during the rest of the stitch-forming cycle. A thread-nipper 18, opened by a cam 18' on the needle-shaft s, and stronger than the nipper 23 nips the thread from just before the entry of the needle into the work on the down-stroke until it has lifted three quarters of its distance above the work on the up-stroke. The effect is that in the second needlestroke the looper draws sufficient thread from the free end for part of the loop against the tension of the nipper 23, but obtains the remainder from the thread supply after the release of the nipper 18 on the up-stroke. A thread-cutter 51 pivoted to the work plate and operated by the overthrow action of the stop mechanism cuts the last loop of a series close to the work.