Patent GB-795329-A (GB)
Title: Zig-zag sewing machine
IPC: D05B19/00
Filed: 1956-06-04
Abstract: 795,329. Sewing machines. NIHON MISHIN SEIZO KABUSHIKI KAISHA. June 4, 1956 [June 2, 1955; Oct. 29, 1955], No. 17199/56. Class 112 Needles, shifting laterally; feeding work. A zig-zag sewing machine has two groups of rotary cams 93, 92, Figs. 1 and 4, and associated followers 101, 96 which determine respectively the needle swing and the rate and direction of the work feed. A single, manually operated control assembly serves to select one of a predetermined number of combinations of a cam from each group to produce a predetermined stitch pattern. To choose a pattern, a spring loaded central knob 126 of the control assembly is pushed inwardly and is held in the position by a detent. In moving it moves a pivoted lever 115 to rotate the shafts 55, 95 on which the cam followers are mounted so as to remove them from the cams. The dial member 128 is then rotated to make the desired selection which is effected by cams 139, 140 in the assembly being thus rotated to move pivoted levers 102, 105 to move the cam followers along the shafts 55, 95 to selected positions. The dial member is then pulled forward to release the knob 126 and the cam followers move to contact the selected cams. The dial member has a "manual" position in which the follower 96 has moved beyond the end cam of its group and is engaged by a member pivoted at 114 and provided with a manually operable member 112. Meanwhile, the follower 101 will have moved to register with a cam producing a simple zig-zag stitch. The needle-bar 28 is reciprocated vertically in a guide 30 pivoted at 31. Lateral swing of the guide is effected by a bar 32 to one end of which is secured a slotted nosepiece 35, Fig. 10, which is urged by spring 34 into contact with a track member 43 pivoted at 42<SP>1</SP> to one arm of a bell-crank lever 44 pivoted at 41<SP>1</SP>. A lever pivoted at 52 has one arm 53 contacting the rear face of the track member and another arm 51 contacting a ledge 54 secured to the shaft 55 carrying the cam follower 101. A link 36, pivoted at 36<SP>1</SP>, carries a pin 37 engaging the slot in the nose-piece 35 and a pin 40 engaged by a forked arm 39 mounted on a shaft 38. A hub 47, loosely mounted on the shaft carries a pin 46 engaging the fork 45 on bell-crank 44. The shaft 38 and hub 47 may be rotated manually by a knob 41 and a lever 50 respectively to move the nosepiece 35 vertically and the pivot pin 42 horizontally so as to vary the amplitude of needle swing the field of operation of the needle. The feed dog 63, Fig. 1, is supported by an arm 64 secured to or integral with a shaft 65 journalled in a pivoted bracket, 66. A lever 69 pivoted intermediate its ends to an arm 68 on the bracket bears at one end of a feed cam on the shaft 56 driving the shuttle 62 and carries at the other end a shaft 70. A link 71 pivotally mounted on the shaft 70 supports at its opposite end a pin on which is pivotally mounted the adjacent end of an arm 72 fixed to the shaft 57. When the angular position of this shaft is such that the axis of this pin is co-linear with the axis on which the lever 69 is pivoted to the arm 68 the action of the feed cam does not rock the bracket 66. In other positions of the shaft the feed is effective in magnitude and direction dependent upon the relative position of the axis referred to. The shaft 57<SP>1</SP> is rocked, in unison with the shaft 95 through an arm 96<SP>1</SP> on the shaft which engages a pin 97 on a lever 98 connected to a crank arm 100 on the shaft 57<SP>1</SP>. The lever 98 is slotted to engage a pivot pin 99 carried by a pivoted lever 109 which may be moved manually to modify the movement transmitted to the shaft 57<SP>1</SP> and thus modify the feed motion. The vertical movement of the feed dog is effected by an eccentric 83, Fig. 11, on shaft 56 operating a bell crank lever 86 carrying a roller 81 contacting the underside of the arm 64 carrying the feed dog. The lever is pivoted at 79, to a lever 78 pivoted at 79<SP>1</SP> and angularly adjustable manually by a disc 76 to raise or lower the pivot 79 and hence the feed dog. The machine may employ two or more needles. Needle thread take-ups. A thread take-up lever 21, Fig. 1, is pivoted at 22 to a link 23 carried by a rotatable shaft 24. One end of the lever is pivotally mounted on the crank pin 27 of a crank arm 26 on the arm shaft 25. The crank pin is also coupled to the needle bar.