GB908215A - Improvements in and relating to sewing machines - Google Patents

Abstract

908,215. Sewing-machines. BERNERUS, D. N., and JOHANSSON, E. L. May 23, 1961 [May 28, 1960; Dec. 3, 1960], No. 18666/61. Class 112. Mechanism for extracting and inserting thread spools, bobbin winding apparatus.-A sewing- machine has two or more rotary hooks which are each movable to a position for co-operation with the sewing-machine needle, means being provided for removing the empty bobbin from a hook and re-insertion of the re-wound bobbin into the same hook when the latter takes a position other than the first-mentioned position. Rotary hooks 67, 68 (Figs. 3 and 4) are mounted on shafts 87, 89 which have coupling halves 147, 151 disposed at diametrically opposite positions on a disc-shaped holder 91 journalled at 93 in a support 94. The disc 91 is biased for rotation about the shaft 93 by a spring 101, wound up by a ratchet-drive, and retained in position by a pawl 111 engaged with one of a pair of diametrically opposite stop shoulders 117, 118. The momentary depression of a treadle 119 by the operator rocks shaft 125, lever 133 then withdrawing the pawl 111 from the shoulder 117 to allow the disc 91 to revolve under the action of the spring 101, the peg 685 on the disc disengages lever 133 from the pawl which then engages the shoulder 118 to stop the disc after it has made half a revolution and a previouslydisengaged hook is disposed to be driven by shaft 65. The operation of the treadle also stops the machine with the needle raised and the shaft 65 in a position where the coupling half 147 can be disengaged from the coupling half 145 as the disc revolves. Release of the treadle restarts the machine, a cam disc 217 mounted beneath the plate 69 then being rotated step-bystep by a disengageable ratchet drive actuated from the shaft 65. A bobbin-winding spindle 153 (Figs. 3 and 6) is journalled in a block 155 which has a peg engaging a groove in the cam disc 217 to move the spindle axially towards and away from the bobbin 79 in the lower hook once every half-revolution of the cam disc and carry the bobbin with it on its split end as the spindle moves away from the hook. At the end of the spindle retraction the ratchet drive to the cam disc is disengaged and a clutch engaged to rotate spindle 153 to wind the thread 267 on to the bobbin. When the bobbin is fully wound a lever 263 (Figs. 3 and 5) is deflected to restart the rotation of the cam disc and disengage the drive to the spindle 153. The spindle then moves towards the hook together with its surrounding sleeve 179 to replace the bobbin in the hook, the sleeve 179 is then maintained in its forward position by a catch 193, previously deflected by the depression of the pedal, while the spindle 153 retracts, leaving the bobbin in the hook. Thread-cutters and end-holders.-A thread manipulator comprising an arm 743 (Fig. 5) is mounted on a pivot 709 which is moved axially and rotated by connections with the disc 217 to cause the arm to engage the thread 267, move to the position shown in Fig. 5 after the bobbin has been fully wound and pass the thread limb extending from the bobbin behind a resilient tensioning washer 746 on the side of the bobbin case. The other limb is passed to a combined thread cutter and end clamp where the thread is severed and the limb held until the spindle is advanced to withdraw the next empty bobbin, the limb then being taken between the bobbin and a disc 185 mounted around the spindle so as to rotate with it but not partake of its axial movement. The thread is then trapped between the disc 185 and the newly withdrawn empty bobbin, the disc and bobbin then rotating together as described to rewind the bobbin. The cutter and clamp comprises a fixed blade 749 and a co-operating movable blade 747 rockable about a screw 751 by a connection with the cam disc 217. The blades are pressed together by a blade spring 755, and the members 747 and 755 have co-operating blunt edges which clamp the thread between them. Construction of rotary hooks.-The bobbins are contained in bobbin cases which are restrained from rotation by projections on plates 75 fixed to the disc 91. The bobbin in the hook which is co-operating with the needle is retained in place by a spring attached to the bedplate of the machine.