GB879300A - Needle bar drive for sewing machines - Google Patents

Abstract

879,300. Sewing machines. SINGER MANUFACTURING CO. June 18, 1959 [June 24, 1958], No. 21004/59. Class 112. In a sewing machine the reciprocating needle bar is turned about its longitudinal axis when leaving the work in order to break the frictional resistance between the needle and the work and thereby reduce the tendency of the work to rise with the needle. As shown, the invention is applied to a zig-zag sewing machine in which the needle bar 7 reciprocates in and pivots about a ball 8. A crank pin 17, carried by the arm shaft 15, is connected by a link 18 to a pin 21 which projects from a yoke 22 pivoted to the needle bar about an axis perpendicular to the plane in which the needle bar oscillates. Pin 21 is slidable in a bearing sleeve 19, on link 18, inclined to the axis of shaft 15, when pin 17 is at its dead-centre positions, at an angle of 8 degrees. Owing to the arrangement the needle bar turns about its axis, the rate of turning being greatest at the top and bottom positions, but the turning then occurring in opposite directions. The arrangement also compensates for the vertical variations of the needle eye relatively to the beak 5 of the vertical axis looptaker 4 during zig zag stitching. Beak 5 and the needle eye are arranged at their optimum relative positions when needle eye is in its central position 23. Pin 21 slides in sleeve 19 to raise the needle eye to an extreme right hand position 23a, and to lower the needle eye to an extreme left hand position 23b, so as to compensate for the respective earlier and later loop-seizing moments corresponding to said positions. Specification 808,351 is referred to.