GB400114A - Improvements in and relating to buttonhole sewing machines - Google Patents

Abstract

400,114. Buttonhole - sewing machines. HUGHES, R. M., 72, Cannon Street, London.-(International Button Hole Sewing Machine Co. ; 502, Harrison Avenue, Boston, U.S.A.) May 2, 1933, No. 12785. [Class 112.] The required length of under-thread to form the first stitch of the next buttonhole is drawn through the throat plate before severing. The thread passes through a tensioning device 17, over a lever 27, through guides 19, 77 and thence through the throat plate 11. The required length of thread is first drawn through the tension device by the lever 27 and is then pulled through the throat plate by a hooked arm 51. The lever 27 is operated when the stitch frame is moved from the stitching to the cutting position by an arm 38 which is mounted on a pivoted block 39. A fixed pin 43 riding over a cam surface 45 tilts the block 39 and rocks over the lever 27. At the same time the thread tension device is released by a cam surface 30 engaging a pin 32. During the sewing operation the arm 51 occupies the full line position shown in Fig. 6. During the operation of the arm 27 the arm 51 moves over the under-thread and clamps it in the throat plate slot 46, but leaves the stay cord free. On the turret rotating, the arm 51 moves to the dotted position and the arm 27 swings back to its original position, thus enabling the thread to be pulled through the throat plate and subsequently severed. In a modification, the thread is pulled through the throat plate as the turret is rotating by an extension 62, Fig. 9.