Patent GB-192833-A (GB)
Title: Improvements in or relating to hemstitching attachment for sewing machine
IPC: D05B73/12
Filed: 1921-11-23
Abstract: 192,833. Hickey, J. Nov. 23, 1921. Hem - stitching machines.-A hem-stitching attachment A, B, Fig. 1, for making the cycle of stitches 53, 51, 52, Fig. 25, is supported by the presser-bar 36 of a household sewing-machine and comprises a piercer 26, a feed-dog m, giving sidewise and forward movement to the work, and means actuated bv the reciprocating needle-bar 38, for operating the said parts. A bridgeplate 39, having pierced apertures with a strengthening lug between them, masks the ordinary feeddog of the machine. A forked arm d, oscillated by a set-screw on the needle-bar 38, is pivoted on a shoulder of a camwheel b, Fig. 4, to which is fixed a ratchet-wheel f. A spring - pressed pawl e, pivoted on the lever d, engages with the ratchet-wheel f and at intervals rotates the cam wheel b, normally held stationary by an internal coiled spring. The forked feed-dog m is pivoted by a pin l in a slot in the base-plate a. A block o in the grooved face of which slides a plate j pivoted at k to the base a, is pivoted to the feed-bar at o<1>, and passes through an aperture in the base-plate a. A roller g, journaled in the plate j, bears in a peripheral camgroove in' the wheel b, which imparts sidewise movements to the feedbar m. A lug y<2> on the feed - bar m projects through an aperture in the base a so as to have longitudinal and lateral motion. On a pin c in the frame-plate a<1> are journaled a duplex ratchet-wheel u<1>, comprising ratchets u, v, of twelve and four teeth respectively, and a cam-plate s, pivoted by a pin r to a link q, which connects it to the arm d. A spring-pressed pawl t, pivoted at r, engages with and intermittently gives one-twelfth of a revolution to the ratchet-wheel u'. An arm x, pivoted to the lug y<2> has a lateral toe y and a notch x<2> for engaging in turn with pins w on the wheel u<1> and a slot r<1> in the pin r. The notch x<2> engages with the pin r at every third stitch to give a forward movement to the feed-bar. A vertical shaft z<1>, journaled in a bracket z on the frame-plate a', carries arms 4, 2, at its upper and lower ends respectively. An arm 9, Fig. 1, having a roller 9a at one end, is hinged at 5<b> to an arm 5, pivoted to the frameplate a' at 6. The arm 9 normally contacts with a stop 5a on the arm 5 under the influence of a spring so that the roller 9a is not over the cam-plate s. The end 5c of the arm 5 bears in a recess 7a in a vertically-movable bar 7, connected at its lower end to a lever-arm 8, which is pivoted at 8<b> to the underside of the baseplate a, and the free end of which bears on the bnidge-plate 39. When the feed-bar moves forward, a pin 3 thereon, Fig. 4, strikes the arm 2, thus rotating the shaft z<1> and the arm 4, which swings the arm 9, the end of which projects through the arm 5, Fig. 1, to bring its roller 9a over the cam-plate s. During the next downward movement of the needle into the hole 50, Fig. 25, the cam-plate s tilts the arms 9, 5, thereby depressing the bar 7; this causes the lever-arm 8 to press on the bridge,-plate and raise the attachment against the presser-bar spring so as to clear the feed-bar m from the work; the feed-bar is then drawn back by contact of the pin r with the lug y<2> on the feed-bar. The grooved piercer 26 is clamped to a piercer-head 24, sliding in a vertical slot 25 in a plate 12, which is adjustably fixed to a hinged plate 13, Fig. 1. A spring-controlled reciprocable plate 29, Fig. 3, slidably supported on the plate 12, has an inclined slot 22b in which bears a roller 23 on the piercer-head 24. A spring-pressed element 14c having an eye 14<d> is hinged at 14a to a stirrup 14, adjustably fixed at 17 to the plate 29. A spring-controlled arm 35, Fig. 2, pivoted to the frame-plate a<1> at 35a, has a dog 36, Fig. 4, at one end, which contacts with the ratchet-wheel v. Once in each cycle, when the dog 36 is in a notch, a toe 35b on the arm 35 will be below the stirrup 14<c>, which can then engage with a pin 11 on the cam-plate s, coaxial with the pin r ; when not in a notch, the toe 35b will bear against the stirrup and hold it out of engagement with the pin 11, which thus actuates the plate 29 to reciprocate the piercer 26 once in each cycle. A latch-plate 33, Fig. 1, has a hooked end 31, adapted to engage a slot in the feed-bar m and so lock the groups A, B in cooperative positions. The plate 29 can be locked in retlracted position with the piercer raised by depressing the plate 33, which engages the pin 20 thereon. The depression of the plate 33 disengages the hooked end thereof from the feedbar m and allows the part A to be swung open. The tongue y may be adjustably fixed to the arm x to permit of variation of the feed. The feed-bar m is provided with an eye m<x>, Fig. 1, through which a cord, to be stitched to the work, may be fed.