GB788081A - Apparatus for obtaining, in a zig-zag sewing machine, automatic cyclic displacement of adjustable amplitude of the fabric to be stitched - Google Patents

Abstract

788,081. Sewing machines. SOC. PER AZIONI FRATELLI BORLETTI. Aug. 8, 1955 [Aug. 6, 1954, May 25, 1955], No. 22847/55. Class 112 Feeding work; needles, shifting laterally. In a zig zag sewing machine cyclic displacement of the work, with variable amplitude, is obtained by a cam 46, Figs. 4 and 7, removably mounted on a rear extension of the cam 25 effecting vibration of the needle, the cam 46 controlling the means for driving the fabric pusher 71, Fig. 2. through a lever 52, 53, the pivot 57 of which is displaceable by a handoperated mechanism to adjust the amplitude of the movement of the. pusher. The invention is described as applied to a machine according to Specification 784,358. The cam 46 is held by a nut 47 on a flange 48 fixed to the shaft 8, a spring 68 facilitating removal of the cam. A window closed by a plate 69 is provided in the rear wall of the frame 2 to permit access to the cam. In modifications, Figs. 5 and 6 (not shown), the flange 48 is mounted in a bearing, fixed to the frame 2 on a separate shaft and is driven from the shaft 8 through a connection or a gear. The pivot 57, Figs. 2 and 7, is carried on a support 58 pivoted at 59 and rigidly connected to an arm 60 resting on an eccentric 61 which may be turned by a knob 63 to adjust the position of the pivot 57. The arms of the lever 52, 53 carry pins 51, 54 contacting respectively the cam 46 and a projection 55 on a lever 56 controlling the mechanism operating the fabric pusher. There is at least one position of the eccentric 61 in which the pin 54 is disengaged from the projection 55. In this event the lever 65 can be manually adjusted by knob 66 said lever coming into contact with lever 56 through the.pin 67 and the control of displacement of the fabric takes place by hand. The lifting of the fabric pusher 71 is effected by a cam 72 mounted on the shaft 20 driving the looper hook. The cam is engaged by a lever 73 pivoted at 74 in a bush 80 which may be fixed in the chosen position on a pin 81. The end 77 of the movable support 78 of the pusher rests on pin 76 carried by the arm 75 of lever 73, the lever and support being coupled by a spring 79 which keeps the lever in contact with the cam. The pin 76 is axially slidable so that it can be disengaged from the support to disconnect the latter from the cam drive. The driving means for the fabric pusher may comprise a fork 82. Figs. 8 and 10, pivoted on a pin 83 and embracing a cam 84 mounted on the upper driving shaft 1. A guide pin 85, fixed in arms 86 rigidly secured to the fork, carries a slide 88 coupled to the link 91 which is coupled to an arm 95, Fig. 2, actuating the pusher support 78 through arm 96. When the slide occupies the central position the support remains stationary. If the slide occupies a position at one end of the guide the end of the link 91 coupled thereto moves through an arc of ten to twelve degrees. Displacement of the slide is effected by a lever 97 pivoted on the pin 83 and having a projection 97<SP>1</SP> carrying a pin with a runner 98 engaged in a fork 99 fixed to the link 91. The slide 88 is pivoted to the upper portion of the fork. The lever 97 can be operated by a hand-actuated member 101 or by a member 102 actuated by the lever 52, the lever being loaded by a spring 103 to maintain projections 97<SP>111</SP>, 97" thereon in contact with one of these members. Either member can be excluded independently of the other, from effecting movement of the lever.