Patent GB-464773-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B1/20
Filed: 1935-10-23
Abstract: 464,773. Sewing-machines. WILLCOX & GIBBS SEWING MACHINE CO. Oct. 23, 1935, No. 29274. Convention date, March 16. [Class 112] An overedge sewing-machine capable of forming a seam with single, double, or triple threads by changing the loopers only, has only one driving connection for operating conjointly both the needle carrier and cutter carrier. Frame ; lubricating. The machine has a main frame 50, Fig. 5, of box-like form forming at the base a reservoir 56 for lubricant 57, which may be drawn off by a plug 57<1>. A glass panel may be inserted so that the oil level may be observed. Rubber plugs 49 are provided to minimize vibration between the machine and the bench. The work plate 60 is provided with a depending apron 69 to prevent oil spray from leaking out at the joint 71, which is further provided with a cork or felt pad 70. The plate 60 supports the trimming mechanism 77, the thread control mechanism 78, the presser device 79, main shaft 81 and driving mechanism 82, 83, 84, 85. The work plate 60 has a series of ducts of large cross-section to direct oil to the various operating mechanisms. The main duct 67 ramifies into subsidiary ducts with ports at suitable places to allow oil to drip on to the bearings and gather in the reservoir where a pump 358 is driven by a pulley operated from the main shaft to keep the oil in circulation. Main driving mechanism. This comprises a shaft 81 supported in bearings suspended from the work plate. The shaft is free to revolve but held against axial movement. The shaft carries an external pulley 99 for driving. Needle operating mechanism. The carrier 121, Figs. 5 and 6 is integral with a shaft 123 carried in earings clamped to the plate 60. The carrier has an arm 122 in which the needle 120 is secured. A rearwardly extending arm 129 is secured to the shaft 123 and carries an eccentric 132 held against the casing to prevent axial movement. The needle is oscillated by a link connection 140 to the crank 118 of the main shaft 81. Trimming mechanism. The upper movable cutter 144 is adjustably carried in an arm 146, Fig. 5, pivoted on a shaft 147 journalled in lugs on the plate 60. The cutter is driven by a link 150 embracing at its lower end an eccentric 132 on the shaft 123 of the needle carrier. The fixed blade 151 is clamped to a plate. As the needle carrier 121 is oscillated, the cutter is operated in unison. Presser. The presser 79, Fig. 3, comprises a carrier 180 on a rod 181 having axial and rotary movements in lugs on the upper face of the plate 60. The block has a finger 183 with a channel 184 to receive a spring carrier arm 185 carrying presser feet 187. The main pressure of the presser is derived from a coil spring 191, the arm 185 giving additional resiliency for passing over cross-seams. The pressure of the spring arm 185 is regulated by a screw 195. The presser is lifted by an arm 203 on the rear of the block 180 provided with the usual treadle connection. Trimmer and presser shifting mechanism. In overedge stitching machines, it is desirable to shift the trimming and presser devices laterally of the line of seam to obtain seams of various widths. The trimming mechanism is shifted by a knurled head 212, Fig. 2, which moves the shaft axially in its bearings to move the trimming closer or further from the needle. The same flange on the shaft of the head 212 also moves the presser shaft 181 in unison. Differential feed. A primary feed-dog 189 is secured to a carrier 235, Fig. 4, and an auxiliary feed-dog 190 is slidably secured to the carrier by a screw 243. Both dogs reciprocate in a slot 244 in the needle plate 245. The carrier 235 is operated for feed lift movement by a crank on the main shaft 81. The feedrocking movements are imparted by a crank arm 250 connected to an eccentric, which is adjustable to vary the feed stroke. The arm 250 has a forward extension 254 pivoted at 255 to a block 256 slidably mounted on a link 257 which is then connected to the auxiliary feed-dog carrier by a link 258. Several auxiliary feed-dogs may be attached to the carrier 258. By adjusting the block 256 up or down the curved arm 257, different movements of the auxiliary feed-dogs relative to the main feed dog are imparted, for crowding, stretching, or compensating the feed of elastic material. Looper mechanism. This comprises a lower looper 289, Fig. 10, and an overedge looper 287. The latter has a retracted position below the plate 60, but advances above the plate for sewing. The looper 289 is carried on a shaft 290, having an arm 292 connected by a link 294 with. crank on the main shaft. The looper is secured to the carrier 288 by screws 297 and is readily interchanged. The overedge looper comprises the carrier 298, readily replaceable looper 299 and shaft 300. The shaft 300 has an arm 301 connected to the crank 117 of the main shaft. Thread tension devices. The needle thread 310 and the looper threads 313, 314 are passed from their tension discs 330, 316, 325 to a common take-up finger 324, Fig. 2, which controls all three threads. The finger 324 is reciprocated once each time the needle and loopers are actuated, to take up the slack thread as the needle and loopers are retracted. Cover. The movable parts above the plate 60 may be enclosed by a cover 360, Fig. 5. Seams. The three-thread seam produced by the device is shown in Fig. 45, and the two-thread seam in Fig. 43, 310 being the needle thread and 314, 313 the looper threads.