Patent GB-1295237-A (GB)
IPC: D05B19/00
Filed: 1970-12-22
Abstract: 1295237 Zig zag sewing machines BROTHER KOGYO KK 22 Dec 1970 [22 Dec 1969] 60944/70 Index F2T 37E1R In an ornamental stitch sewing maching having at least one zigzag cam 6 connected by a first adjustable linkage to a laterally movable needle frame 4 and at least one feed control cam 8 connected by a second adjustable linkage to a feed dog 131, a manually operable setting means 31 is provided operatively connected with the first and second linkages for adjusting the linkages simultaneously to vary in constant proportion the  lateral movement of the needle and the feed of the feed dog to alter the size but not shape of a stitch pattern. In the non-automatic condition of the machine the control 31, in a different range, adjusts the second linkage and feed only and a manual control 40 adjusts the first linkage and stitch width. In a second embodiment the manual amplitude control controls both the feed and amplitude in the automatic pattern condition. The first linkage between the cams 6 on the machine shaft 2 and the needle frame 4 comprises an arm 14 mounted slidably on a splined shaft 11 and engaging a cam 6 to pivot the shaft 11 and an arm 13 at its end. The arm 13 abuts and pivots on arm 19 of a bell crank lever pivoted at 18 and having a depending arm 20 which pivots a block 28 about a pivot 30. The block 28 has a groove 29 in which is slidable a block 66 pivoted to a link 65 which rocks the needle frame 4. Manual adjustment of the zigzag linkage is carried out by a knob 36 rotation of which pivots a sinuous lever 26 about the pivot 18 thereby moving the pivot 30 of the block 28 to give a left, right or middle needle field, and by pivoting of a lever 40 anticlockwise, rotation of which rotates a lever 42 mounted on a common shaft 41 Fig.4 and having a lug 46 which engages a lug 49 on a spring loaded lever 47, to lower the generally vertical link 64 and hence the slider 66 in the groove 29, to reduce the needle amplitude. Adjustment of the needle movement during automatic pattern stitching to vary the pattern size is carried out by rotation of the knob 31 with the scale (33) adjacent the mark (34) Fig.3, (not shown) anticlockwise when the varying radius cam surface 69 engages a pin 74 on the lever 73 to move the link 64 by means of the lever 73, bell crank 53, lugs 57 and 51 and lever 47. Feed means. The feed dog 131 is oscillated from a cam 132 on the machine shaft 2 through a Pitman 130 controlled by a feed controller 102 which is either controlled manually by rotation of the knob 31 in the clockwise position of its field of movement when the scale (32) is adjacent the mark (34) Fig.3 (not shown) causing axial movement of the nose 67, depression of a button 35 in the knob 31 reversing the feed, or automatically from the feed cam 8. In the latter case undulations of the cam are transmitted to the controller 102 through an arm 23 which is moved simultaneously with the arm 14, engaging the cam, a splined oscilatable shaft 12 and an arm 21 at its end, Fig.6, a centrally pivoted lever 90, an end pivoted lever 81 and a rod 105, the central pivot 93 being slidable in a groove 100 of the machine frame to adjust the displacement ratio of the linkage. The pivot 93 is moved simultaneously with the slider 66 to adjust a stich pattern size on rotation of the knob 31 through a pin 77 engaging a cam 70, a rod 79 and a bell crank 95. Second Embodiment (Figs.10, 11, 12). During manual control, the lever 40a in the range 0 to 5 on the scale 109a, actuates the rod 64 and slider 66 on the knob 31a in the range 0 to 4 adjusts the feed controller 102a as above and also a lever 113 is held out of engagement with a cam surface 112 of the lever 40a by an abutment 122 on a depending arm 120 which has a pin 121 engaging a circumferential groove 119 below the knob 31a. During automatic stitch control the knob 31a is rotated anticlockwise until the inclined portion of the groove 119 engages the pin 121 and pushes the abutment 122 away from the lever 113, allowing its lower end to engage the cam surface 112. The lever 40a is moved in the range 5 to 7 on the scale 109a to adjust the pattern width through the link 64 and slider 66 and to simultaneously adjust the feed by pivoting the lever 113 which moves a pin 124 through link 127 and lever 125 to alter the displacement ratio of the linkage between the arm 21a on the splined shaft 12a and the rod 105a connected to the feed controller 102a.