GB1065565A - Needle jogging mechanisms - Google Patents

Abstract

1,065,565. Sewing machines. SINGER CO. July 31, 1965, No. 32878/65. Heading DIG. A zig zag sewing machine comprises dual eccentric means mounted on a driven shaft and connected to the needle bar gate for vibrating the latter, the arrangement being such that dwell periods occur in the vibration while the needle is penetrating the work. As shown, the needle bar 30 is mounted in a gate 32 rigid with a rod 33 slidable axially in bearings 34, gate 32 being engaged on each side by a fixed pin 35. Two eccentrics 50, 51 are rigid with a shaft 52 driven by 2 to 1 reduction gearing from the arm shaft 20. The eccentrics are embraced by respective straps 55, 56 pivoted at 58 and 59 respectively to an integrating link 57 pivoted at 62 to an arm 61. One end of the latter is pivoted at 63 to a bracket 64 rigid with rod 33. The other end is pivoted to a pin slidable on a substantially vertical rod 68, Fig. 2 not shown. The amplitude of vibration and the neutral position of gate 32 are respectively determined by the inclination of rod 68 and the position of the latter along the longitudinal axis of the machine. Rod 68 is fixed in a frame 69 having a lateral pin journalled eccentrically in a sheave 80 journalled eccentrically in a sheave 81 which is journalled in the machine frame. A block 90 pivoted on sheave 80 is slidable in a slot 91 in a fixed bracket 87. Sheave 81 is rotated by means of a handle 83 for varying the longitudinal position of rod 68. Bracket 69 is pivoted to a block 102, Fig. 2, slidable in a groove formed in a member 101 supported by two parallel pivoted arms 103, 104. A handle 100, rigid with arm 103, may be turned for varying the inclination of rod 68. The geometrical centres of the eccentrics 50, 51 are spaced at 80 degrees apart about shaft 52. The plane through shaft 32 and pivot 63 is perpendicular to the plane through shaft 52 and pivot 62. The distance between the geometric centre of each eccentric 50, 51 and its associated pivot 58, 59 is 2.25 times the eccentricity of the eccentrics. The distance between the pivots 58, 59 is 2.5 times the eccentricity, and the height of an isocells triangle defined by the pivots 58, 59, 62 is 2.8 times the eccentricity. The arrangement is thereby such that link 57 turns about 62 without raising arm 61 to shift gate 32 while the neddle is engaging the work.