Patent GB-142170-A (GB)
Title: Improvements in or relating to machines adapted for operation upon parts of boots orshoes or leather articles
IPC: D05B15/00
Filed: 1919-01-24
Abstract: 142,170. British United Shoe Machinery Co., (United Shoe Machinery Corporation). Jan. 24, 1919. Sewing-machines; stopping-gear.-Boot - sole sewing-machines and other boot-sole machinery are provided with a stop-gear by means of which a machine can be stopped at one. of two points in the cycle of operations as selected by the operator. In the case of a sewing-machine, the machine may be stopped with the awl in the work or out of it, and in the latter case with the presserfoot raised or not. The stop-gear includes a slow-speed drive and a brake, which are brought into operation in succession by means of a cam-motion, and the invention consists essentially in the provision of a lostmotion device by means of which a part of the movement of the cam can, at will, be rendered ineffectual, and the moment when the brake becomes operative thereby delayed. The slowspeed clutch member 328, Fig. 10, is carried by a pulley 314 driven independently of the main drive of the machine. The inner member 334 rotates with one 92 of the shafts of the machine. The outer brake member 340 is fixed, and the inner member 338 is integral with the clutch member 334 and the operating-cam 360. The parts 334, 338, 360 can slide axially upon the shaft 92 and are normally held in a middle position by a spring. One end of a lever 368 engages the cam-groove, and the other end, during the continued operation of the machine, is free to oscillate under the control of the cam. To initiate the stopping operation after the main drive is disconnected, an upwardly-pressed bolt 372, Fig. 11, is freed and, rising, enters a recess in the free end of the lever 368 and locks it to a slide 376 in which the bolt is mounted. This occurs at the inner position of the lever's oscillation, and when the slide 376 reaches a stop provided by the end of a bolt 380, the lever 368 is prevented from further movement, and thereafter, by its continued rotation, the cam 360 is moved to bring the clutch member 334 into engagement with the slow-speed driving-member 314. The further rotation of the cam, if the lever 368 remained held, would release the clutch and put in the brake by causing the cam to slide in the opposite direction. The return movement of the lever 368 is, however, opposed by one or other of two pawls 424, 426, Fig. 11, of different lengths. If the longer pawl 424 is in operative position, no return of the lever 368 is possible, and the cam causes the early engagement of the brake. If the shorter pawl 426 is in operative position, a portion of the cam movement is absorbed in moving the lever 368 to bring the slide 376 up to the pawl, and only subsequently is the brake brought into action. The use of the longer pawl secures the stopping of the machine with both needle and awl clear of the work, and the use of the shorter pawl, with the awl in the work. A further arrangement provides that, when the longer pawl is used, the devices can be set, at will, to lifs the presser-foot and release the rear thread lock and the thread tension. This involves the use of a lever 460, Figs. 2 and 10, for operating these parts which is put into operative connexion with a cam only when a spring-urged latch lever is freed by the stopping- devices. The freeing is effected when two stops are removed from the control of the latch lever. One stop 482 is part of the slide 376, and is removed in each stopping operation; the other stop 484 is controlled by a hand-lever 458, Figs. 2 and 11, which also determines which of the two parts. shall be operative. The hand-lever, which is bent forwardly from the plane of Fig. 11, is integral with a barrel 454. When the hand-lever is turned up from the horizontal position, a longitudinal projection 452 engages a toe 450 of the longer pawl 424 and, raising it, depresses the body nf the pawl into an inoperative position. When the hand-lever is horizontal, the longer pawl is left inoperative. When the hand-lever is depressed, the longer pawl remains operative as before, but a cam-groove 498 is used to remove the stop 484 from the latch lever 472, Fig. 10, and in the stopping operation, the lever 460 transmits presserlifting and thread-releasing movements. The pawls 424, 426, in the continued operation of the machine, are held below the path of the engaging part of the slide 376 by a link 444 having a pin- and-slot connexion with the treadle-rod 408. When this rod is raised, the pawls wait to snap behind the slide 376 on its outward movement, excepting when, in the case of the longer pawl, the toe 450 is engaged. To permit this independent movement of the pawls, the link 444 is pinned to the pawl 426, and the other pawl is constrained to move with it normally by a spring 442. In order that the upward movement of the bolt 372 may be delayed to ensure the early disconnexion of the main drive, the bolt 372 is normally held depressed by a latch 432 pivoted at 396 upon a crosshead secured to the bolt. A lever 394, also pivoted at 396, is pinned to the rod 408 and moves the latch only after certain lost motion due to the clearance between a lug 406 on the lever 394 and a recess 404 on the boss of the latch 432. Driving.-The main drive is by way of a pivoted shaft 266 urged upwardly by a spring 294 into a position in which the belt 272 is slack. The machine is driven when the treadle 302 is held depressed. The slow-speed clutch pulley 314 is driven independently by a belt 316. Perforating-devices ; feed by awl.-A sliding carrier 18, Fig. 4, is connected by a link 54 to an oscillating arm 56 on a shaft 58 having a second arm linked by a pitman to a rotary crank. The awl-carrier slide is mounted upon parallel swing- ing levers 22, 24. A second lever 30, Fig. 5, is fixed upon the shaft of the lever 24 and is actuated by a pitman 32. The pitman is pivoted upon a swinging link 42, shown in dotted lines, and is actuated by a cam-groove engaging the bowl 34. The link 42 swings upon the pin of a crank 44 on a shaft 46, and the feed is varied by rotating the crank. The crank centre is concentric with the extreme upper position of the pin uniting the pitman and the swinging link, so that for all lengths of feed, the awl is brought to the same position at the end of each feeding movement. For adjustment of the feed, the crank-shaft has a second arm 50 prolonged to form a hand-adjuster. The end of this arm is tubular and encloses a spring-pressed plunger, the end of which engages teeth cut in a fixed plate 52. Presser-bars, lifted automatically and non-automatically; presser-bar springs.-The presser-bar 98, Fig. 4, is given a uniform lift from work of any thickness by means of a gripping-lever 118 mounted in a sleeve sliding upon the presser-bar and normally held upon the top of a presser-bar .bearing bracket 102 by a spring 114. The lever 118 is actuated through a link 120 and lever 122 on a cam-oscillated shaft 124. The presser-bar can be lifted by a hand-lever 154, Fig. 4, on a shaft 146 having a second arm 142. The end of the arm 142 engages between two laterally projecting lugs on the top of the presser-bar. The presser spring is helical and situated concentric with the presser shaft 146 perpendicular to the presser-bar. One end of the spring extends tangentially and presses upon the end of the arm 142 and the preseer-bar. The other end is secured to a sleeve concentric with the shaft 146, and which may be rotated to vary the pressure of the spring upon the presserbar by means of a hand-operated worm 166. The hand-lever is connected by a link 464, Figs. 4 and 5, to the stop-gear. Thread tensioning devices.-The thread tension comprises a thread disk 170, Fig. 4, situated between a fixed friction disk 176 and a movable friction disk 180 pressed towards the disk 176 by a spring 182, but periodically moved against the spring to release the tension by the lengthways movement of a central rod 172 to which it is fixed. The rod 172 is jointed to rod 186 pivoting upon a pin-point and actuated by a ball-and-socket connexion with an arm 196. Upon a second arm 198 of this shaft, a cranked lever 200 is pivoted. This lever is joined at one end by a link 204 to an arm on the shaft 146 of the presser-lifting gear, and at the other end by a link 206 to a cam-actu. ated lever 208, Fig. 5. Normally, the link 206 and the arm 202 form a toggle strut and transmit to the shaft 196 the tension-releasing movements. When the presser is raised, the cranked lever is rotated, and the shaft 196 is actuated by the bending of the toggle. The thread lock on the work side of the pull-off comprises a thread roll 218 and a clamping-lever 222 actuated by engagement with a lever 226 on a shaft 228, which is oscillated by two oppositely-disposed cam-levers 230, 232, Fig. 5, bearing upon separate cam-surfaces on a camdrum. The thread lock or the supply side of the pull-off comprises a thread roll 242 and a clamping-lever 244 secured upon the shaft 196 of the tension-release mechanism. This arrangement provides for the release of the latter thread lock when the presser is raised