GB931214A - Lock stick zigzag sewing machine - Google Patents

Abstract

931,214. Sewing-machines. SINGER MANUFACTURING CO. May 4, 1962 [May 12, 1961], No.17126/62. Class 112. A lock-stitch swing-needle zigzag sewing - machine comprises means for winding thread on the looptaker bobbin during operation and of the needle bar and looptaker, and control means for initiating and terminating operation of the winding means, the zig-zag mechanism being rendered inoperative upon initiation of winding, and operative upon termination of winding. The main shaft 14, carrying a gear 40 meshing with a pinion on a driving motor, is coupled by a crank 15 and a connecting-rod 16 to the needle bar 17, and is also coupled via gears 31, 32 and a vertical shaft 33 to the bed shaft 34, the latter being coupled by gears 35 to a hollow vertical shaft 36 driving a rotary hook 37. The needle bar 17 is slidable in a stationary universal joint 18 and a universal joint 19 carried by a swinging gate 20 coupled by a link 29 to a pivoted bar 28 adapted to be oscillated by engagement with cam followers 27 selectively engageable with a cam pack 26 rotated via a gear 25 from shaft 14. Rotary hook 37 comprises a hollow body 60 rigid with shaft 36 and formed with a loop-seizing beak 62 and an inner circumferential flange 61 supporting a bobbin carrier 63. The latter is held from rotation by a pair of opposed spring fingers 67 projecting fron a stationary plate 66. A bobbin 70 has an upper flange 71 supported by the bobbin carrier 63, and a lower flange 72 which is spaced from the internal wall 69 of the bobbin carrier and is formed with a concentric ring of holes 76. A pin 73, upstanding from the bobbin, engages a hole in an arm 74 pivoted at 75 to the bobbin carrier. A radial, thread-guiding groove 77 formed in the bobbin carrier is covered by a thread-tensioning leafspring 78 formed with a thread-guiding notch 79. A pin 80, slidable in shaft 36 carries a bobbinwinding member 81 having a radial finger 84 engaged in a recess 85 in the rotary body 60. Pin 80 is adapted to be raised by engagement therewith of a spring finger 92, when a pin 82 on the bobbin winder enters one of the holes 76 to drive the bobbin, a leaf-spring 86 on the bobbin winder engages beak 62 to clamp the needle thread thereagainst, and an upstanding, circular rib 83 on the bobbin winder enters the gap between wall 69 and flange 72 to direct the needle thread, drawn from the supply by beak 62, on to the bobbin, the bobbin winder being lowered momentarily during each revolution, to ensure correct thread clamping, by the co-operation of a cam-plate 93 on pin 80 with a fixed abutment 94. Thread winding is controlled by a rotary knob 103 which is fixed to a pin 102 journalled in a stationary block 100, and carries a dial 104 provided with graduations 105 visible through an aperture 106 in a fixed plate 101. Pin 102 carries a ratchet-wheel 107 and a hub 108 formed with a cam notch 109. A lever 110, journalled on pin 102, is formed with a notch 117 loosely embracing a fixed pin 118, and carries a pair of pawls 111 biased by springs 112 into engagement with the ratchet-wheel 107 at a distance apart of one-half of the pitch of the ratchet teeth. A control lever 121, pivoted at 120 on block 100, has an abutment 122 normally engaged in the notch 109, a notch 131 loosely embracing pin 118, and an arm 123 normally disposed above a finger 124 on a vertical bar 125. The lower end of the latter is pivoted to one end of a lever 90, the other end of which carries the spring finger 92. The upper end of bar 125 is pivoted to one arm of a bell-crank lever 127 the other arm of which is connected by a bar 140 to one arm of a bellcrank lever 143. A bar 145 depending from the other end of the latter underlies the tensionrelieving lever 146 of the thread tensioner 22, and a stud 151 carried by bar 140 is positioned adjacent a block 152 on link 29. A finger 129 on bar 125 abuts the feed-advance pitman 57, the upper end of which embraces an eccentric 59 on shaft 14, and the lower end of which is biased by a spring 116 to engage one arm 56 of a T-shaped slot therein with a pin 55 on an arm 54 rigid with the feed-advance shaft 53. If knob 103 is turned clockwise about 20 degrees while the machine is operating, abutment 122 is shifted to the periphery of hub 108 and lever 121 is swung counterclockwise to depress bar 125. Thereby, finger 92 raises pin 80 to initiate bobbin winding, bar 145 is raised to operate the thread tension-release lever 146, stud 151 engages block 152 to swing bar 28 away from the cam followers 27 and to hold the needle bar gate in one position, and finger 129 co-operates with a cam surface 130 on pitman 57, whereby the latter is swung to position pin 55 in a vertical arm 58 of the T-shaped slot for immobilizing the feed, while a pin 114 carried by pitman 57 engages a slot 113 in the pawl-carrying lever 110 to oscillate the latter. Ratchet-wheel 107 then turns clockwise until abutment 122 re-enters notch 109, when the bobbin is fully wound and normal operation of the machine re-commences. The amount of thread wound on the bobbin progressively diminishes as knob 103 is initially turned increasingly beyond 20 degrees, the dial 104 being marked with numbers indicating the length in yards of thread so wound.