Patent GB-833311-A (GB)
Title: Improvements in or relating to sewing machines for automatically producing stitches forming various patterns
IPC: D05B19/02
Filed: 1958-05-02
Abstract: 833,311. Sewing machines. MEFINA S.A. May 2, 1958 [May 15, 1957], No. 14080/58 Class 112 Needles, shifting laterally; work-feeding. In a sewing machine having a control device adapted to act upon a needle bar or upon a work-feed element for producing a predetermined pattern of stitches, the control device comprises a digital programme controller adapted to supply electric signals to a series of contact studs, driving means connected mechanically to the needle bar or feed element, an exploring member which is displaced with the driven element to make contact with said studs in succession, and means, operated electrically at the instant when the exploring member contacts that stud supplied with current by the programme controller, for stopping the driving means in a position thus determined by the programme controller. As shown, the swinging needle barcarrying gate 3 of a zig-zag sewing machine is connected by a link 5 to a control member 6 pivoted at 7. Means for driving the control member comprise an electromagnet 8 and a spring 9 acting in opposition to each other. An exploring arm 6a on the control member is movable over a series of contact studs 10a to 10e, and a sector 6b on the control member is formed with a series of notches 11 which correspond with the said studs. A finger 12 on a lever 13 is adapted to enter one or another of the notches when an electromagnet 15 is energized, to immobilize the control member. The studs are connected to respective contacts 31 in a digital programme controlling device 23. Contacts 31 are connected in succession, in accordance with the programme, to a contact 34. The electromagnet 8 is energized by a current source 16 through the agency of a thyratron 17 and a contact 18 controlled by the programme controller 23. The grid of thyratron 17 is supplied with current by a source 19 at instants controlled by a ring 20 mounted on a shaft 21 driven by the sewing machine. Arm 6a is connected to the source 19, and contact 34 is connected to the grid of a thyratron 24 whose output circuit supplies the electromagnet 15. As soon as arm 6a makes contact with the stud which is at that time in communication with the grid of thyratron 24, electromagnet 15 is energized and the control member 6 is locked. The feed circuit of electromagnet 15 is controlled by a ring 25 on shaft 21, whereby electromagnet 15 is released after each stitch. Th programme control device 23 comprises two insulating plates 26, 27 interconnected by five rods 29a to 29e and carried by a rotatable shaft 28. The rods, which are situated at different radial distances from the axis of the latter, project beyond plate 26 to make contact with respective fixed concentric rings 30a to 30e the latter being respectively connected to the studs 10a to 10e. Mounted on the rods are several series of five contact discs 31 separated from each other by insulating discs 32. The discs are formed with holes 33 for the passage therethrough of the rods, but in each disc 31 one of the holes designated at 33<SP>1</SP>, is small enough for its edges to make electrical contact with the rod. Each disc 31 is thus connected to a different rod. The discs 31 are formed peripherally with noses 31<SP>1</SP> which, on the step-bystep rotation of shaft 28, make successive contact with the contact 34. One of the discs 31 of each series, designated as 32<SP>1</SP>, is in the form of a cam and controls the contact 18. The contacts 18 and 34 are displaceable to co-operate with one or other of the series of discs, in order to produce various natterns of stitches.