Patent GB-811956-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B81/00
Filed: 1957-02-21
Abstract: 811,956. Sewing machines, KAGIYAMA, K. Feb. 21, 1957 [April 11, 1956], No. 5844/57. Class 112 A portable sewing machine for chain stitching comprises a curved needle arranged to osillate in a vertical plane, and a looper arranged to oscillate in a horizontal plane, the axis of oscillation of the needle being arranged to slide vertically, and vertical movement, synchronized with the oscillation of the needle, being imparted to said axis by a driving member via an operating linkage. Stitch formation. Work feed by presser foot. The curved needle 29 is carried by an arm 28 fixed to a horizontal shaft 1 driven from a shaft 17 via a crank 24 and a connecting rod 26. Shaft 17 is driven by a pulley 19 and belt 20 from an electric motor mounted in the machine frame. The looper 11, which is of bullet shape, is carried by one arm of a lever 31 pivoted about a fixed vertical pin 32, the other arm being forked to embrace the ball-shaped end 30<SP>1</SP> of a pitman 30 actuated by an eccentric 23 on shaft 17. A thread take-up arm 16, formed with a thread eye 16<SP>1</SP>, is pivoted at 34 to the frame and has a pin 33 disposed in a slot 15<SP>1</SP> in a pitman 15 actuated by an eccentric 22 on shaft 17. A spring 40 biases pin 33 to one end of slot 15<SP>1</SP>. The needle shaft 1 is journalled in a vertically movable slide 3 biased upwardly by a spring 4. The rounded end 6<SP>1</SP> of a lever 6 pivoted at 7 to the frame bears on the slide 3. The other end of lever 6 is pivoted at 5 to an arm 9 formed with a projection 9<SP>1</SP> which co-operates with a projection 10<SP>1</SP> on a cam disc 10 fixed to shaft 17, whereby slide 3 reciprocates vertically. A screw 8, which is threaded into lever 6 and abuts arm 9, serves to adjust the vertical movement of slide 3 to suit the thickness of the work. The needle penetrates the work at spaced points to form a loop on the upper surface, and the looper moves into the loop to retain the latter while the needle retracts. The previous stitch is then set and the work is fed, whereby on its next penetrating stroke the needle passes through said held loop, the looper then retracting to free the loop. A workfeeding presser foot 14<SP>1</SP> is carried by a pitman 14 which is actuated by an eccentric 25 on shaft 17 and is pivotally suspended by a link from the frame. In a modification, Fig. 6, the machine is hand-driven. A compression spring 21<SP>1</SP> is disposed between a pair of handles 20<SP>1</SP>, one of which is fixed and the other of which is pivoted about an inclined axis. A bar 19<SP>1</SP>, fixed to the movable handle, is slotted to embrace the ball-shaped upper end of an arm 36 pivoted to an arm 37 of a lever 24<SP>1</SP> fulcrummed about a horizontal shaft 17'. Movement of handle 20<SP>1</SP> thereby serves to oscillate lever 24<SP>1</SP>, and movement of the latter is conveyed by respective connecting rods 14, 15, 26 and 30 to the feeding foot 14<SP>1</SP>, the thread take-up 16, the needle shaft 1, and the looper 11. The rounded upper end 10<SP>11</SP> of lever 24<SP>1</SP> co-operates with a roller 9<SP>11</SP> on an arm 9 to reciprocate slide 3.