| 摘要 |
1,195,079. Sewing machines. AMERICAN SAFETY TABLE CO. 14 Dec., 1967 [2 Nov., 1967], No. 56921/67. Heading D1G. A lock stitch sewing machine comprises an electrically-heated element disposed beneath the throat plate and adjacent the needle-passing hole therein, and thread pick-up means operative when actuated to pick up only the needle thread extending from the needle for drawing thread from the supply, and then to catch the needle and bobbin threads extending from the work and to shift said threads against the heated element for severing the same. When the needle is rising and the thread takeup leaver 25 is adjacent its lowest position, a thread pick-up arm 35, disposed beneath the throat plate 31 is swung clockwise by the energisation of a rotary solenoid 42. The bobbin thread 41 and the limb 40a of the needle thread extending from the work are then deflected by the inclined outer edge 44 of arm 35, and the limit 40b of needle thread extending from the needle lodges in a notch 43 in the forward edge of arm 35, whereby sufficient thread to commence the next seam is drawn from the supply. Solenoid 42 is then de-energised, whereby arm 35 swings counter-clockwise and the thread 41 and thread limb 40b, now engaged with the rear edige 45 of arm 35, are shifted against an electrically-heated element 36 and are severed thereat. Solenoid 42 is energised when a switch 51 is closed by an energised relay 52. Element 36 is heated when a switch 55 is closed by an energised relay 56. The machine is arranged to stop automatically with the needle in its lowest position by means comprising three rotary slip rings 83, 84, 85 interconnected by a bar 85'. Actuation of a treadle then serves to raise the presser foot, to release the thread tension, and to close a switch 62 whereby the needle is raised to its highest position. A rotary segment 64, connected to bar 85', on contacting a brush 65 serves to energise relay 52 via a switch 63 which is coupled to switch 62 for actuation therewith. Thereby relay 42 is energised and a switch blade 59 is shifted to a contact 60 for charging a capacitor 57. Relay 52 is de-energised when segment 64 disengages from brush 65, whereby relay 42 is de-energised and blade 59 re-engages a contact 58 for dischanging capacitor 57 through relay 56 for heating element 36 through temporarily closed switch 55. |
