GB1160670A - Controlled Loose Stitching Mechanism for Chainstitch Sewing Machines - Google Patents

Abstract

1,160,670. Sewing machines. SINGER CO. 23 July, 1968 [28 July, 1967], No. 35067/68. Heading D1G. A chain stitch sewing machine comprises a thread tensioner, a stationary thread-guide adapted to accommodate a thread passing from the tensioner to the needle, first movable thread take-up means operably connected with the needle drive to manipulate a thread loop between said guide and the needle for paying out said loop during the needle penetration stroke and drawing in said loop during the needle withdrawal stroke, second movable thread take-up means operatively connected with the needle drive to manipulate a thread loop between said guide and tensioner for drawing in said loop during the needle penetration stroke and paying out said loop during the needle withdrawal stroke, and manually-operable means for regulating the amount by which the size of the thread loop manipulated by the second take-up means exceeds the size of the thread loop manipulated by the first take-up means. The needle bar 48, driven from the arm shaft 40, is rigid with a take-up arm 62 formed with thread-passing holes 63. A shaft 65, oscillated from shaft 40, is rigid with a take-up arm 64 projecting fdrwardly from the machine arm and formed with thread-passing holes 63. A shaft 91, oscillated from shaft 40, is rigid with a pull-off arm 90 projecting rearwardly from the machine arm. Arms 62, 64 and 90 move up and down in synchronism. Arm 90 is disposed between vertical limbs 83, of a wire loop 82. The upper ends of the latter are formed as respective eyelets 80, 81, and the lower end is slidably mounted in a fixed washer (85) and is connected by a pivotal link 105 to a crank arm 104 at the rear end of a shaft 101 journalled in fixed brackets 102, 103 and turnable by a front knob 100 for raising and lowering the eyelets 80, 81. Thread from a supply passes through a tensioner 100 and then through the eyelets 80, 81, the loop between the latter extending around the lower edge of arm 90. From eyelet 80 the thread passes from the rear to the front of the machine arm through a fixed, obliquely-disposed guide tube 73, and then passes to needle 52 via a fixed eyelet 69, arm 64, arm 62, a lightly-loaded tensioner 60 and a guide arm 59 on the needle bar 48. The arrangement is such that arm 90 in a down stroke draws more thread through tensioner 110 than the arms 62, 64 draw from the work during their upward stitch-setting strokes, to produce loose stitches, the degree of looseness being adjustable by varying the vertical position of eyelets 80, 81. Needle 52 co-operates with a threaded fourmotion looper 22. The looper thread passes through fixed guide eyelets 31 and under a fixed bar 32 positioned therebetween and associated with a take-up disc 30 mounted on a rotary shaft 20.