Patent GB-672183-A (GB)
Title: Control means for sewing machines
IPC: D05B27/24
Filed: 1950-08-23
Abstract: 672,183. Sewing-machines. SINGER MANUFACTURING CO. Aug. 23, 1950 [May 5, 1950], No. 20833/50. Class 112. [Also in Group XXIV] Means for actuating an element controlling sewing-machine mechanism,.such as mechanism for laterally vibrating the needle, comprises a lever movable by the machine operator and connected to the element through a pair of interengaging cranks of which one is adjustable relative to the other to alter the ratio between the movement of the lever and that of the element. The machine described produces a monogram copying a pattern by pantograph mechanism and has a laterally vibrating needle controlled by a knee-lever to vary the width of the stitching, means being provided for altering the ratio of reproduction of the pattern and for automatically producing corresponding alteration in the ratio between the movement of the knee-lever and the resulting change in amplitude of the needle vibration. Feed by clamps; stands.-In the embodiment described, the sewing-machine 14, Fig. 1, is mounted on a turntable 106 in the top of its stand 19, the axis of the turntable being beneath the neutral position of the needle, so that the plane of needle vibration may be turned relatively to the work by a handle 108. The work is held by a tambour 16 connected by a pantographic linkage 15 (not described) to a stylus head 17 which is similar to that described in Specification 673,317 and is moved by hand over the pattern to be followed; the pattern is carried in a pocket 29 beneath a transparent cover on an apron 24. The apron is slidable in and out from the stand, and the linkage is so arranged that this sliding alters the ratio of movement between the tracing head 17 and the workholder 16; means are provided for holding the apron in the desired position. Needles, vibrating laterally.-The needle-bar 49, Fig. 4, reciprocates in a gate 51 pivoted at its upper end to a screw-adjusted mounting and provided at its lower end with a lug 54 carrying a pivoted block 55 embraced by a forked end of a lever 58, pivotally mounted at 57, whereby the gate 51 is vibrated. A horizontal pitman connected to the upper end of the lever 58 has a forked end embracing a cam on a transverse shaft 66 driven by helical gearing from the main shaft 38; a roller on the pitman near the forked end slidably engages a guide which is fixed on an angularly adjustable spindle 76 to vary the longitudinal movement of the pitman resulting from its lateral throw and thus to vary the amplitude of vibration of the needle. The position of the spindle 76 is controlled by a push-rod 90 acting on an arm 70 on the spindle against the action of a spring 85 which urges the mechanism to the position in which no vibration of the needle takes place; the arm 70 moves between stops 82, 84. The push-rod 90 is actuated by a knee-lever 18, Figs. 1 and 2, carried by the apron 24, through the linkage described below, which automatically alters the ratio of movement between the lever 18 and the rod 90 when the apron is moved to vary the ratio of reproduction of the linkage 15. The lever 18 is integral with a rod 86, Fig. 2, rotatable against a spring 101 in bearing lugs 87, 88 on the apron 24, the stem of the lever 18 being guided by a U-member 89, to prevent the rod from moving endwise relatively to the apron; the rear end of the rod 86 is bent to form an arm 97 which engages a rod 96 carried by arms 98, 99 on a spindle 92 carried by the stand 19, these arms being rigid with a horizontal arm 100 through which the rod 90, Fig. 1, is actuated. The rod 96 is inclined, so that as the apron 24 is pulled out from the position shown, carrying the rod 86 with it so that the arm 97 moves along the rod 96, the point of contact between the arm and rod 96 moves away from the rod 86 and towards the spindle 92, the ratio of movement between the latter arms and the knee-lever 18 being consequently varied; the arm 99 has a plurality of holes in which the rod 96 may be placed, so that its inclination, and thus the rate of change of ratio, may be varied. The horizontal arm 100 engages beneath a bar 110 pivoted to the table 19 at 115, and the latter bar engages, on the axis of the turntable 106, beneath a similar bar hinged beneath the turntable and having its free end engaging beneath the end of the push-rod 90, which is thus actuated by the arm 100 regardless of the position of the turntable. Needles, driving.-The needle-bar 49, Fig. 4, is driven from the crank 40 on the main shaft 38 by a pitman 44 which is hinged at its ends to collars carried respectively by the crank-pin and by a pin on a block 48 secured to the needle-bar, the lateral vibration of the needle being thus provided for.