GB1300621A - Improvements in sewing machines - Google Patents

Abstract

1300621 Sewing HER MAJESTY INDU STRIES Inc 1 April 1970 15498/70 Heading DIG Feeding by movement of stitch forming apparatus; frames; machine bridging work. The upper and lower stitching instrumentalities 20, 22, are movable in unison along two axes X, Y, in the same plane and are rotatable in unison about an axis Z perpendicular to the plane. To this end the units 20, 22 are each separately mounted on cross slides (Fig: 2-5 not shown) and driven in the appropriate directions in the plane by motors driving lead screws, further motors 38, 62 rotating the units in unison about the stitching axis. The motors may be controlled by the logic system shown in Fig. 7. A photo-electric cell 50 mounted on a circular presser foot detects the edge of the fabric to be stitched and provides stepped inputs to the motors 38, 62, by means of the multi-vibrators 150, 148 and components 142, 144, 146, 152, 154, 156, 158, 170, 172. The units thus turn parallel to the work edge, displacing the sine/cosine potentiometer 42 which provides appropriate signals to the X axis motors 98, 116 and the Y axis motors 82, 104. Zero detector devices 176, 178 supplied from the potentiometer brushes 136, 138, detect a zero signal therefrom as the outputs pass through zero and reverse the polarity of the supply to the X, Y motors accordingly. A Schmitt trigger network 188, receiving a signal from a needle drive shaft when the needle is in the work, then supplies a signal to the NOR gates 184, 186 connected to the motor supply circuits to prevent X, Y motion when the needle is in the work. Where the stitching is to be controlled by a tape or programme a servo drive (Fig. 10 not shown) is substituted. The servo drive includes tacho feed back and selsyn units (300, 302). It is stated that the machine may be supported within rings or half rings (380, 382, Fig. 16 not shown) when rotation about and movement along all three axes X, Y and Z permit sewing along any three dimensional compound curve. Using air; machines designed for special goods; seams; feed by belts. The specification describes the sewing of pants and skirts (Fig. 11 not shown) fed to the stitching area by belts (328); of collars and cuffs (Fig. 12 not shown) brought to the sewing area by clamps (338) or, (Figs. 13, 13A not shown) stitched from a number of superimposed plies subsequently cut out by a die not shown; of small parts sewn to larger parts (Fig. 14 not shown). The Specification also states that cloth workpieces may be sewn to a paper support or belt which is stripped away automatically after the sewing operation. Air jets (326, Fig. 11 not shown) may be directed against the bottom of the workpiece to maintain a slight tension therein.