Patent GB-895788-A (GB)
Title: Improvements relating to zig-zag sewing machines for the production of ornamental ordecorative designs or seams
IPC: D05B19/00
Filed: 1959-07-20
Abstract: 895,788. Sewing machines. GRITZNERKAYSER A.G. July 20, 1959 [July 22, 1958], No. 24778/59. Class 112. A zig-zag sewing machine has a pattern control means including rotatable pattern generating cam discs 32 rotatable about a fixed axis, a corresponding number of co-axially mounted followers or fingers 53 independently angularly displaceable about the axis of a spring loaded pattern control rocker 35 and selector means for connecting a cam disc with its corresponding finger, in which an abutment 56 for restraining the angular movement of the finger relative to the rocker is displaceably guided on the rocker parallel to the oscillatory axis thereof and along the row of followers by a fork or like member of the selector means to permit oscillation of the abutment relative to the selector means. A bearing block 1 is secured to the arm of a sewing machine through bores 2 and one end of a frame 8 is received in the block 1 between lugs 4. The other end of the frame 8 is clamped to the sewing machine arm thereby forming a rigid structure. A worm gear 16 driven in known manner and a pinion 17 both on a tubular shaft 18 are rotatably mounted in the frame 8 and the interchangeable cam discs 32 are driven through gears 17, 19. The rocker 35, journalled on a pin 34 disposed in the sewing machine arm, is connected by a link 42 to a double-armed rocker lever 44, which is rotatable relative to the frame 8 by an axle 15. A guide member 47 (Fig. 3) is clamped by a screw 46 to the lower end of the lever 44 and a block 48, which is adjustable in height by a stitch setting device, reciprocates in the member 47. The block 48 oscillates the needle bar rocker 51 via a lever 50. The magnitude of the oscillations depends on the distance between the screw 49 and the axle 15 and is reduced to zero when the two coincide. The rocker 35 is mounted on a sleeve 52 which extends between brackets 36, 37 and the fingers 53 are independently mounted on the sleeve 52. An abutment 56 slides on a rod 40 of the rocker frame and is kept in contact with one of the fingers 53 by a spring 57 attached to the bracket 36 (Fig. 3) thereby bringing the finger in contact with a cam disc and imparting a rocking movement to the rocker 35 as the cam rotates. The cam disc nearest the gear 19 has no finger and may control other devices such as the cloth feed. A stationary thrust plate 55 has a finger 53 and is the equivalent of a circular cam. Retaining springs 58 keep the inoperative fingers clear of the cam discs to eliminate unnecessary wear and noise. The bearing block 1 carries a helically grooved spindle 65 upon which is a sleeve 66 carrying a forked extension 68 to engage the abutment 56 in such manner that relative movement between the two parts 56, 68, is possible without them disengaging when the rocker 35 pivots about the pin 34. A screw 69 in the sleeve 66 engages in the helical groove and as the spindle 65 is turned the extension 68 displaces the abutment 56 along the row of fingers 53. A ratchet wheel 71 on one end of the spindle 65 engages with a pawl 74 when the abutment is aligned with a finger 53. A pinion 75 on the other end of the spindle 65 is driven by a selector knob 78 through a pinion 76. The knob 78 is also provided with a spindle 79 having a tapered end 80 and has provision for axial movement within the hub 77. Normally the knob 78 is pressed away from the sewing machine arm by a spring so that the tapered end of the spindle 79 is in contact with one arm of a three armed lever 81 as in Fig. 3. The lever is pivoted at 82 and the other end bears on a pin 83 shown in Fig. 2 in the plate 37. When the knob 78 is pushed towards the interior of the sewing machine arm the taper 80 on the spindle 79 rotates the arm 81 anti-clockwise and the rocker 35 and the abutment 56, pivoting about the pin 34, rotate clockwise. The fingers are retained by a stop surface 84 so that the abutment 56 is clear of them while traversing. When the knob 78 is released the arm 81 moves down the taper and the spring 57 restores the condition shown in Fig. 3. A further pinion 85 meshing with a pinion 86 operates a stitch pattern indicator carrying a pointer 90 which is visible through an opening in the sewing machine arm.