GB696782A - Mechanism for the setting of the starting point of the oscilaltion of the needle andthe adjustment of the amplitude of said oscillation in zig-zag sewing machines - Google Patents

Abstract

696,782. Sewing machines. SOC. PER AZIONI FRATELLI BORLETTI. April 2, 1951 [April 7, 1950], No. 7629/51. Class 112. Needles, vibrating laterally.-In order to provide for independent variation of the amplitude of needle vibration and alteration of the line from which vibration starts in a machine in which the vibration is effected by a forked bar 4 actuated by a cam 3, a fulcrum pin 5 of the bar 4 is carried by a block sliding in a guide 14 which can be moved bodily by an arm 17 from one control lever and moved angularly from a second control lever by a shaft jointed at its ends to permit axial and swinging movement. In the embodiment shown, the guide 14 is pivotally mounted by means of a vertical pin in the end of the arm 17, which is fixed to a spindle carrying the first control lever 21 at its lower end, and the pin of the guide is connected by a universal joint 22 to a shaft 25 which is connected at its lower end by a similar joint 27 to the second control lever 31; the joints 22, 27 allow for relative lateral and vertical movements, but not angular movements, of the parts they connect, so that shifting of the lever 31 on its pivot causes corresponding angular movement of the guide 14 on its pin to vary the amplitude of longitudinal reciprocation of the rod 4. Movement of the lever 21 carries the guide 14 obliquely across the length of the lever 4, thus moving this lever longitudinally, so that the line of stitching produced when the guide is set perpendicular to the lever 4 (in which position the needle does not vibrate) is shifted laterally; this movement of the guide also causes the reciprocation therein of the pin 5 to occur mainly or wholly to one side of the pivot pin of the guide so that the needle vibration produced when the guide is in a suitable angular position lies correspondingly more or less to one side of the line of stitching which would be produced if the vibration did not occur. In the mechanism shown, the lever 4 is connected to a lever 8 pivotally mounted at 9 and engaging at its lower end the needle-bar gate 10 which is pivoted at 11; in a modification the lever 8 is replaced by two arms extending from a vertical rock-shaft.