Patent GB-751953-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B39/00
Filed: 1951-11-30
Abstract: 751,953. Sewing-machines. JONES & SONS (MACHINE PARTS), Ltd., G. E., and HUGGIN, F. B. HOLMES-. Dec. 1, 1952 [Nov. 30, 1951], No. 28197/51. Class 112. [Also in Groups XXIV and XXXV] The work is held on a carriage which is reciprocated, by a rotary cam, on a primary carriage moved along a guide by a rotary cam against the force of restoring means, the two carriages moving in mutually perpendicular paths and the two cams rotating uni-directionally in unison, each cam being formed in two separate relativelyadjustable halves so that the length of the effective portion may be varied. Means are provided for actuating the stitch-forming devices, and for controlling and cutting the threads at the end of an operation. The work may be trimmed during sewing. In the machine shown, for stitching together layers of material to form a collar, a clamp C, Fig. 4 (rear view), of the kind described in Specification 734,835, formed in the shape of the collar, is closed on the layers of material to be sewn and is then attached by locating-pins 90 and electromagnets 91 to a carriage 12 mounted on rollers between upper and lower rails 14 of a second carriage 11 which is guided on a fixed vertical rail 8 by means of a roller 16a engaging the rear face of the rail and a pair of grooved rollers engaging the front corner an anchorage 57, the pulleys 54, 56 being mounted in a block 41 sliding on a rail 42 provided with a follower roller 40 acted on by a cam 23; the anchorage 57 is formed by a lever which bears against an adjustable stop 60. The cam-shaft is driven through change-speed gears, to vary the rate of feed of the work, by an electric motor which also drives the other parts of the machine, and it also carries a cam 25 which imparts horizontal movements to the carriage 12 by means of mechanism 76, 80, 82 against the force of a spring 74 acting on a linkage 67, 69, 70 connecting the two carriages. The cams are removable from the shaft for interchanging with others of different form, and are secured by a hand-nut 31 and a locating-pin; in order to provide for stitching lines of similar form but different overall dimensions, each cam may be formed in two relatively-adjustable parts, such as 23a, 23b in Fig. 21, which shows the block 41 provided with two follower rollers 40a, 40b, for actuation successively by the two cam parts, the roller 40b being adjustable on the block 41 to suit the varying step between the two cam parts. A horizontal needle-bar is reciprocated in fixed guides by a crank on a shaft connected through an electromagnetic clutch with a shaft on the input side of the gearbox driving the cams; a shaft 139, Fig. 4, connected by bevel gearing with the needle-bar shaft, carries a loop-taker 140 to co-operate with the needle in forming lock-stitches. Thread passes to the needle between two discs of a tension device pressed together by a spring in the usual way, and over take-up pins carried between two discs on the end of the needle-bar shaft; the flat end of a solenoid-actuated lever lies between the spring and the adjacent disc of the tension device, whereby the tension is released when the machine stops. The needle of the rail. The carriage 11 is urged upwards by a weight attached to it by chains passing over pulleys, and is moved downwards as required by a chain 50 passing over pulleys 51 . . . 56 to and locking threads are cut at the end of a stitching operation by scissors comprising two blades 197, Fig. 18, formed on the upper end of a vertical lever 195 mounted on the carriage 12 and two pivoted blades 200, 202 biased to the open position by a spring 211; the movement of the carriage 12 near the end of the stitching carries the lever 195 into contact with a fixed member whereby the lever is rocked against the action of a spring to bring a nose 209 on the blade 200 into engagement with a lug on the work-clamp C, whereby the blade is given a closing movement which is also transmitted to the blade 202 by interengaging parts on the two blades. Operation of the machine is started by reversal of a manual switch which energizes a clutch in the main drive to start the movement of the cams 23, 25, whereupon a pin on one of the cams allows a mercury switch 158, Fig. 4, to reverse, thus energizing the needle-driving clutch and the magnets 91 securing the workclamp to the carriage. At the end of the stitching operation the carriage 11 engages the manual switch to restore it to its initial position, thus disconnecting the driving motor and energizing a brake to stop the motor; the pin on the cam restores the mercury switch 158, de-energizing the needle-driving clutch and the clampsecuring magnets and energizing the tensionrelease solenoid and an eddy-current brake (see Group XXXV) which stops the mechanism with the needle clear of the work and with the cam 23 clear of its follower roller so that the carriage 11 is allowed to return to its upper position under the action of its counterweight. In a modified arrangement of the machine, the layers of material are fed in continuous lengths, passing together over a roller at the top of the frame, this roller being movable endwise to allow for the lateral movement of the carriage 12; the work-clamp is permanently secured to the carriage, and its hand closing-levers are dispensed with, the magnets 91 being used to close it instead. According to the Provisional Specification, the cams may be actuated through an intermittent drive, so that the work is moved only when the needle is clear of it; the work may be fixed and the stitch-forming devices mounted on the carriage; the needle may be actuated by a cam from which the follower may be retracted, against a spring by a solenoid energized at the end of the stitching to carry the needle clear of the work, this solenoid being de-energized by insertion of the clamp into the carriage for a new operation; a number of switches may be arranged around the cams for actuation by a member on the latter to start and stop stitching in order to produce several disconnected sets of stitches in the work; the cam-follower which is not required to be effective at a given time may be retracted mechanically or electromagnetically under control of the cams; the needle carriage may have attached to it a trimming knife acting at each needle stroke to cut the work at an adjustable distance from the line of stitching; the workcarriage may be arranged in an inclined or horizontal plane; for a long line of stitching several cams operating successively may be used to avoid the need for very large cams, and the cams for transverse movement may move more slowly than the others so as to have the same effective length.