GB928200A - Lock stitch sewing machines - Google Patents

Abstract

928,200. Sewing-machines. SINGER MANUFACTURING CO. March 9, 1962 [March 17, 1961], No. 9175/62. Class 112. In a lock-stitch sewing-machine, successive needle thread loops taken by the looptaker are adapted to be wound in succession on the bobbin associated with the looptaker. As shown, the looptaker is an oscillating shuttle. It is stated that the looptaker may, alternatively, be a rotary hook. Stitch-forming; bobbin winding.-The shuttle 43 has an arcuate peripheral rib 44 which extends between radial abutments 51, 52, and also projects beyond abutment 51 to form a looptaking beak 53. Rib 44 is journalled in an open-sided groove 45 which is formed in a fixed supporting member 46 and which has its open side closed by a retainer member 47 hinged to member 46. A shuttle driver 49, fixed to an oscillating shaft 50, has a pair of driving fingers 48 coacting with the respective abutments 51 and 52. A bobbin case 131 has a sleeve 130 journalled on a post 121 projecting outwardly from the rear wall of the shuttle, and an end flange 132 from which projects a rotation-preventing finger 160 engaged in a groove 161 formed in a fixed member 162. A bobbin 142, journalled on sleeve 130, has an end flange 141 disposed under a peripheral lip 140 formed on flanges 132, and an end flange 143 formed with opposed peripheral lips 144, 145. Lip 144 extends towards lip 140 to leave a peripheral thread-passing slot 146. A friction member has a flange 149 abutting flange 143, and an eccentric sleeve 152 journalled on sleeve 130. A leaf-spring 150 is anchored at one end to lip 145 and bears at its other end both on flange 149 to urge the latter against flange 143 whereby the friction member rotates with the bobbin, and also bears on sleeve 152 to urge the latter against sleeve 130 for braking the rotation of the bobbin. Said braking may be varied by turning sleeve 152 relative to sleeve 130. The bobbin holder is held within the shuttle by a latch member 135 which is slidably mounted on flange 132 and is biased by a spring 136 into engagement with a peripheral groove formed near the free end of post 121. For bobbin winding, latch 135 is released by a lever 137 and the bobbin case is drawn to an outward position in which the slot 146 is exposed, and in which it is held by a magnet 168 mounted in a support 165 fixed to member 47. Thread from a spool 90 passes to the needle 40 in succession through a fixed guide 91, a main tensioner 92, a take-up 39, an auxiliary tensioner 96 interposed between fixed guides 95, and a guide 97 on the needle bar 37. For bobbin winding, the free end of the thread is fixed in a clamp 98 carried by the presser bar 99, the bobbin case is shifted to its outer position, and if the work is in position the presser foot 100 is raised and the feed dog 70 is lowered. The machine is then operated, and the successive loops of thread taken by the shuttle beak 53 are passed through the slot 146 and are successively wound on the bobbin under control of the take-up 39. On completion of bobbin winding, the bobbin case is returned to its inner position when a knife edge 170, formed on lip 140 to one side of the rotation-preventing finger 160, severs the limb of thread extending between the needle and clamp 98. In an alternative arrangement, thread is drawn through. the needle eye and, after being passed through a fixed guide 111, is wound on an auxiliary spool 110, and the thread between guide 91 and tensioner 92 is secured in a fixed clamp 112. Thread for bobbin winding is then drawn from spool 110, and the knife edge 170 is arranged on the opposite side of finger 160 so as to sever the limb of thread extending between the needle and the clamp 112. Alternatively, bobbin thread may be taken exclusively from Spool 110, when the thread, after being passed through guide 111, the needle, guides 97 and 95, the tensioner 96, the take-up 39 and the tensioner 92, has its free end secured in the clamp 112. Feeding; connecting upper and lower shafts.- The feed dog 70 is carried by a feed bar 71, one end of which is pivoted to cranks 72 on a feed advance shaft 73 oscillated via a crank 75 and pitman 76 from the upper arm shaft 34. The other end of the feed bar is connected by a pivotal link 77 to a crank 78 on a feed advance shaft 79. A retractible pivot pin 80, connecting link 77 and crank 78, is carried by a bracket 84 which is slidable on shaft 79 and is connected by a link 85 to a crank 86 turnable by means of a handle 87 for retracting the pivot pin 80 to immobilize the feed. Shaft 79 is oscillated via a crank 82 and a coacting cam 83 on a rockshaft 56. The latter is oscillated via a crank 58 and pitman 59 from the arm shaft 34. A bifurcated arm 55 on shaft 56 embraces a crankpin 54 on the shuttle driving-shaft 50 for oscillating the latter.