Patent GB-1167986-A (GB)
Title: Improvements in or relating to Sewing Apparatus
IPC: D05B85/06
Filed: 1967-07-06
Abstract: 1,167,986. Sewing machines. UNION SPECIAL MACHINE CO. 6 July, 1967 [12 July, 1966], No. 31167/67. Heading D1G. A sewing machine for automatically performing stitching operations on successive edge portions of a workpiece comprises workpiece edge-guiding means, means responsive to the completion of the stitching of one of the edges for automatically turning the workpiece so as to align another edge in the direction of work feed, and means for raising the presser foot on completion of the stitching of an edge and for retaining the presser foot in the raised position while said turning means is operative. The sewing machine is provided with sensing means adapted to detect the interconnection of successive edges and to control electrical circuit means, whereby, at the completion of the stitching of one of the edges, the sewing machine is stopped, the presser foot is raised, and the workpiece is turned until said sensing means detects that the succeeding edge is urged in the direction of work feed. An overedge sewing machine 10, mounted on a platform 11 carried by a pillar 14, is driven via a belt 19 from a shaft 17 driven in turn by a motor 15 via a clutch controlled by a solenoid 16. Shaft 17 is also coupled by a belt 26 and one-way clutch to a motor (20) which, when energised, drives the sewing machine slowly, and which, when subsequently energised to rotate in the reverse direction by means of a radial reflective strip on a disc 30 driven by the sewing machine and co-operating with a sensor 22, as described in specification 1,156,851, stops the sewing machine with the needle lowered. A main work-supporting plate 52 is relatively narrow and has curved leading and trailing corners. The work hangs over the leading corner and the right hand edge is thereby urged against a guide surface 60 adjustably mounted on an auxiliary work-supporting plate 61. A main presser foot (36c) is spring-biased downwardly and raised by energisation of a solenoid (35). An auxiliary presser foot 70, arranged in advance of the stitching point 57, has a workengaging plate 70a depending from a bracket 70b which is secured, together with a workengaging spring finger 68, by a screw 68a to one end of a bar 72 pivoted intermediately at 73 to plate 61. The other end carries a counterweight 76 adapted to raise foot 70, and is connected to the armature of a solenoid 77, energisation of which serves to lower foot 70 and to actuate a switch 80. A completed workpiece, on leaving the stitching point, moves counterclockwise over the curved trailing corner of plate 52, whereby the thread chain is extended laterally leftwards to be severed by a knife 47 disposed in the line of stitching. Knife 47 is carried by the armature of a solenoid 40, energisation of which serves to engage knife 47 with a hardened work-supporting surface. A motor 101 has a vertical shaft 100 which is aligned with the stitching point 57 and carries a disc 103 which rotates counterclockwise and is formed on its upper surface with radial grooves 104. A fixed sleeve 99, co-axial with shaft 100, is slidably and rotatably engaged by a sleeve 90c rigid with the upper end of a downwardly-curved arm 90, the lower end of which carries a spring-mounted work-engaging foot 91. The forked inner end of a lever 111 carries pins 110 engaging a circumferential groove in sleeve 90c, and the outer end of lever 111 is connected to the armature of a solenoid 116. A spring 120 acts on lever 111 to bias arm 90 upwardly, and a spring 123 acts on arm 90 to bias the latter clockwise against an adjustable stop 118. Energisation of solenoid 116 on completion of the stitching of one edge of a workpiece, when the machine is stopped with the needle engaged in the work and the presser feet are raised, serves to lower arm 90 for engaging a member 122, carried thereby, with one of the grooves 104, and foot 91 with the work. Arm 90 then turns counterclockwise through an angle equal to the angle between adjacent edges of the work, when solenoid 116 is de-energised. The lower portion of the work is supported by a disc 130 carried by a shaft 132 coupled by a belt 136 to a motor (139) and driven by the latter counter-clockwise while the workpiece is being turned. Shaft 132 also carries a disc 135 having spaced cam lobes 148 adapted to actuate a switch (141). Automatic operation is effected via a electrical control circuit energised by the covering and exposure of suitably positioned photocells 64, 65, 67 illuminated by a lamp, in conjunction with the actuation of the switches 80 and (141). Photocell 64 is adjustably carried at the leading edge of plate 61 in alignment with guide 60. Photocell 65 is carried by plate 61 adjacent guide 60 and in advance of the stitch-forming point. Photocell 67 is carried at the leading edge of plate 52. The photocells operate relays adapted to control the stopping and starting of the machine, the lifting of the presser feet, the number of turns and the extent of each turn at the completion of the respective edges, and the formation and severing of the thread chain on completion of the final edge. As shown, the edges E1, E2 and E3 of a rectangular workpiece are stitched in succession. In a modification the needle is halted at random and the work is turned about the needle thread extending therefrom. In a further modification, multi-needles are halted in the raised position and the work is turned about an auxiliary unthreaded needle which is then projected into the work.