Patent GB-206710-A (GB)
Title: Sewing machine
IPC: D05B65/00
Filed: 1922-11-21
Abstract: 206,710. Fairweather, W., (Singer Manufacturing Co.). Nov. 21, 1922. Button-attaching machines; starting and stopping gear; thread-cutters and thread-rod holders; threads, controlling, otherwise than in stitch-forming; presser-bars with periodic control. - In a sewing-machine, for attaching buttons or for barring, tacking &c., having a hook which gives the needle-loop a half twist in casting it about a bobbin to juxtapose the bobbin thread and the work limb of the needle-loop, devices are provided which detain the last needle-loop acted on by the take-up and sever the under-thread and the; limb of the needle-thread attached to the work close up to the work so as to leave a sumcient length of needle-loop thread for starting the next sequence of stitches. An automatic brake is provided for the stop-motion and as this actuates the cutter too abrupt an action of the latter is prevented. In the button-attaching machine shown, the stop motion of which is as described in Specification 206.374, a jogging work-clamp is actuated through levers by a cam 25, and a stopmotion is provided comprising a stop-lever 44 carrying a belt-shifter 46, and a, plunger 47 engaging a positive stopping-cam 48 the lever also' having a limited sidewise shock-absorbing movement. The lever is held out of stopping position by a catch 49 released at the close of a sewing operation by a projection on the camwheel. An arm 77 pivoted to a bracket 76 on the, underside of the throat plate carries a needleloop detaining and bobbin-thread pull-off blade 78 on which is a cutting edge coacting with a blade, on a plate 85. Also mounted on the arm are a nipper-blade 80 pressing against the part 78 and a barbed plate 80<1> which nips the needle thread at the beginning of an operation. A lever 90, Fig. 5, is pivoted to the base and connected by a link 92 to an arm 77 and by a link 93 to a lug 94 projecting from a. slide bar 95 at the rear end of which is a notched block 96 engaged by the end of a lever 98, Fig. 2, pivoted at 99 and actuated by a follower engaging a cam-groove 101. The block 96 also carries a stud 102 engaged by a lever 103 pivoted at 104, the other arm 105 of this lever carrying a pin 106 which is pressed outward by a spring 107 and adapted to enter a recess in the lever 44 just before its sidewise movement. A presser-bar 109, Fig. 4, carries a bracket 111, 112 engaged by the end of a lifting arm 114. A bracket 116 on the presserbar engages an arm 27<1> on the button-clamp 27 which may thus be lifted by the presser-bar. An arm secured to the presser-bar has a cam-surface engaged by a cam on a U-shaped lever 120 pivoted at 121, the other arm of this lever engaging the release-pin of the tension 122. Two arms 123, 124 axe secured to the arm 114, the arm 123 having eyes 125 for a treadle connection and the arm 124 having a projection 124<1> adapted to engage one or other of a pair of projections 126 on the cam-wheel. A lever 130, 132, one end of which rests on the periphery of the cam-wheel and engages a recess 127, is connected by a rod 133 to an arm 134 bearing against the rear end of a lever 135 pivoted at 136 to the needle-bar and in contact at its lower end with a spring needle-thread clamp 137 which tends to open when not restrained by the lever 135. On starting the machine the needle-thread clamp is closed on the first reciprocation and the tension is open, while a recess 127 and projection 126 are in contact with their respective followers and the bobbin thread is held by the nipper 80. As the follower on the lever 98 passes from the part 141 to the dwell 139 of its cam the cutting mechanism is moved partly back and the barbed blade 80<1> pulls the needle-thread to one side and nips it. The tension then closes and the thread-clamp opens. On the fourth reciprocation the cam-follower of the lever 98 passes :nto the dwell 101 completely withdrawing the cutter-mechanism and releasing the needle-thread end. At the end of an operation the needle makes several tying-stitches in the same hole and on its last rise as the loop is cast off and drawn up by the take up the thread-cutter advances and the detainer 78 pulls off the bobbinthread and enters the loop. The rotary hook has caused the positions of the limbs of the loop to be reversed as shown in Fig. 13 so that the limb a attached to the work together with the bobbinthread are in a position to be cut by the blade. The final sidewise motion of the stopping-lever 44 is communicated by the lever 103 to the slidebar 95 and gives an additional thread-severing movement to the cutter, this being permitted by an enlargement 138 in the cam track.