Patent GB-190222929-A (GB)
Title: Improvements in Stitch Forming Mechanism for Shoe and Leather Sewing Machines.
Inventor: IMRAY OLIVER
Filed: 1902-10-21
Granted: 1903-02-12
Abstract: 22,929. Imray, O., [Duplessis Pegging and Sewing Machine Co.]. Oct. 21. Boot - sole stitching - machines; leather - sewing machines; lock-stitch hook sewing-machines.-The oscillating lock-stitch hook in a shoe and leather sewing-machine is replaced by a revolving hook, enabling the machine to be worked more rapidly ; means are also provided for reducing friction between the needle thread and the bobbin case of the locking-thread as the needle-thread loop is drawn over the case, and for preventing abrasion as the thread is removed from the barbed needle which draws the loop np through the material. The revolving hook 17, Figs. 4, 7, and 10, consists of an arcuate extension of a disc 18 supported in a block 15, Fig. 7, by a shaft 19, on which is mounted a screw-gear pinion 33 extended to form a bearing-sleeve in the bearing-block 35. The shaft 19 is secured by lock-nuts 36, and the end may be recessed and split laterally to receive a wedge screw 37<b> to tighten the locknuts. The hook is driven by a pinion 39 mounted on a shaft 40 worked continuously but irregularly by cam mechanism. The hook 17 has a forked nose, the inner limb 41, Figs. 4 and 10, of which passes into the loop of the needle thread, to remove it from the barbed needle, while the outer and shorter limb 42 passes outside the loop to direct it into the fork. The thread-hook disc 18, Figs. 4 and 7, has a shallow conical recess 47, which is faced by a corresponding recess in a ring 22 on a bracket 20, Fig. 14, forming a support for the bobbin case. The conical surface of the ring 22, is provided with three irregularly-spaced bosses 27, 28, 29, on the lower one 27 of which the bobbin case rests loosely and works from side to side, the bosses 28, 29 formmg buffers against which the bobbin reacts. A notch 30 is also provided in the centre of the boss 27 to engage a lip 31, Fig. 4, on the bobbin case to prevent its rotation. The conical recess in the disc 18 is provided with a slightly-eccentric heel 48 just in advance of the point of the upper limb 41 of the hook, which pushes the bobbin case over against the opposite boss as the loop is being drawn over, to give the loop a frictionless passage. A recess 51<a>, Fig. 14, in the conical part of the bobbin bracket adjacent to the boss 27 further enables one lap of the thread loop to pass round the bobbin without excessive friction. When the loop is cast off, the motion of the hook is stopped or retarded to allow time for the take-up of the loop and for the formation of a new loop. Figs. 11 and 2 show the application of the arrangements to oscillating hooks. The thread hook 52 consists of a point 53, a re-curved nose 54, and a grooved tail-shield 55. A triangular lump 57 projects beyond the nose 54 a suficient distance to throw the bobbin case from side to side for the free passage of the loop over it. Needles, hook, cast-off devices for.-In order to take off the needle-thread loop from the barbed needle without abrasion, the needle passes into a groove 45, Fig. 7, in the limb 41, which clears the thread from the barb. The motion of the hook ceases momentarily for the entrance and withdrawal of the needle, and is then resumed. The oscillating hook, Fig. 11, is also provided with a groove 56 to remove the needle loop from the needle. Needle shields -The revolving hook is provided with an outwardly-projecting rim 49, Fig. 4, which forms a shield or guard for the barb of the needle as the loop is drawn down tight, and also prevents entanglement of the loop with the needle.