Patent GB-152252-A (GB)
Title: Improvements in and relating to sewing machines
IPC: D05B15/02
Filed: 1920-01-20
Abstract: 152,252. Thompson, W. P., (Union Special Machine Co.). Jan. 20, 1920. Multiple-needle machines; loop-stitching.-In a chain-stitch sewing-machine for darning fabrics having a pair of needles arranged tandem fashion and each sewing its own seam, the work is fed by hand and means are provided for positively laying the threads in the hooks of the needles and for positioning the thread loops in the needle paths irrespective of the direction of feed of the work. The needles are arranged in a line diagonal to the general direction of feed of the work. The thread-handling means comprises a pair of thread-engaging fingers 104, 105, Fig. 23, which move across the needle paths when the needles are retracted, engaging both needle threads and positioning them in rear of the needles, and a pair of thread-carriers 106, 107 which carry the threads around the shanks of the needles 42, 43 respectively and lay them in the hooks thereof. A pair of loop-positioners 168, 169 carried on a common shank 170 actuated by connexions from cams on the main shaft, engage the thread loops beneath the work so that the needles in their ascent after the feed of the work pass through the loops to form the chain stitch. The threadengaging fingers have a common shank 103, Fig. 8, fixed to a rod 143 carried in a collar 114 having a universal joint connexion with the rod 13 that actuates the presser-foot, the threadcarriers having the common shank 108 fixed to a rod 109 carried by a collar 110 being similarly connected to the rod 13, whereby both the fingers and carriers are raised and lowered with the presser-foot. The rods 143, 109 are actuated by a pair of oscillating and axially moving shafts each carrying a crank connected to sleeves, one of which is shown at 122, on the rods and operated through connexions by cams on the main shaft. The needles 42, 43 are carried on a bar 44, Fig. 5, reciprocated by connexions from a shaft 56 rocked by an eccentric on the main shaft. Each needle has a latch 62 carrying lugs 63, 64 engaged by a collar 65 which is moved relatively to the needles by an arm 68. This arm is connected by a link 71 with one arm of a bell-crank lever pivoted on the needle bar and carrying on the other arm a roll 76 engaging a vertical slot in a guide member 79 which is horizontally oscillated by a crank on a cam-actuated rock-shaft. The latches are thus actuated to open the needle hooks to receive the threads when the needles are above th work, thereafter closing as the needles pass through the work. Presser-feet; work-supports.-The underside of the presser foot 11 and the upper side of the work support are cupped to form a recess around the stitching points to permit the threads to be set while the work is clamped. Presser-bars with periodic control. - The presser-foot 11 carried on the bar 12, Fig. 8, is pressed on to the work by a spring 17 of adjustable tension and is lifted once for each stitch by the rod 13 which carries a collar 14 having a pin 16 engaging a hole in the bar 12. A pin 26 on the rod 13 is engaged by a lever 23 pivoted at 24 and adjustably connected to a link 27 which is moved axially by a cam. The presser-foot is prevented from upward movement while the needles are penetrating the work, by a dog 35 held by a spring 37 in the path of the collar 14. To allow the presser-foot to be lifted, the dog is pushed out of the path of the collar at every stitch by the crank that moves the thread-engaging fingers. Thread-cutters and thread-end holders; threads, controlling otherwise than in stitch forming.- Means are provided for pulling off a length of thread and for severing the threads beneath the work on the completion cf sewing. A knife 199 carried by a lever 200 pivoted at 201 is arranged to operate in the plane of the needles to cut one limb of both needle loops simultaneously, and is actuated by a treadle connected to a rod 211 through the connexions shown in Fig. 31. The lever 209 is connected through the link 222 to the arm 218 which carries a thread-eye for each thread, and has a lost-motion connexion 212, 213 with the cutter-actuating mechanism whereby depression of the treadle first draws off thread for the succeeding stitching operation and then cuts the thread ends, which are thereafter drawn under the presser-foot by removal of the work and are clamped thereby at the commencement of the next operation. A recess in the Bange of a pulley 215 on the cam-shaft 3 entered by the end 214 of the lever 209 ensures that the treadle can only be actuated when the sewing is completed and the needles are withdrawn from the work.