Patent GB-418823-A (GB)
Title: Improvements in or relating to shoe inseam sewing machines
IPC: D05B15/00
Filed: 1933-04-27
Abstract: 418,823. Sewing-machines. BRITISH UNITED SHOE MACHINERY CO., Ltd., Belgrave Road, Leicester.-(United Shoe Machinery Corporation ; 140, Federal Street, Boston, U.S.A.) April 27, 1933, No. 12261. [Class 112.] Chain stitching; feed by needles and awls.- Inseam chain stitch curved hook needle boot sole sewing-machines are arranged so that the chain of stitches is laid in a channel of the insole instead of on the welt. The needle is arranged to enter the work from the channel side instead of the welt side. Co-operating with the needle 2 is a take-up 4, Fig. 1, which when the needle is through the work, Fig. 15, is actuated to draw the needle loop tight around the shank of the needle and exert a stitchsetting pull. A needle-threading looper 6 with an eye through which the thread passes also co-operates with the needle. A thread finger 8 engages the thread between the work and the looper to draw out a bight of thread, Fig. 15. The take up lever 4 is actuated by a cam groove in a cam disc 12, Fig. 4. This groove engages a follower on the rear end of the take-up lever and actuates the lever positively to draw the thread tight round the shank of the needle, as shown in Fig. 15, and then draw the amount of thread required for the next stitch from the supply through a tension wheel 16. The take up lever is acted upon by a spring 18, Fig. 1, coiled around the pivot shaft 20 to which the lever is fixed. The spring 18 causes the lever to exert a yielding tension on the thread between the tension wheel 16 and the work. A curved awl 26 enters the work on the side opposite the channel. The needle, which is of smaller radius than in machines in which the needle enters at the welt side, follows the retracting awl and enters the work from the channel side and emerges at the correct point in the welt or upper. To ensure that the needle follows the path of the awl accurately, the needle and awl are provided at their points with corresponding surfaces, Fig. 15, which come into overlapping relation as the awl withdraws from and the needle goes through, the work, forming a continuous instrument during the needle advancing stroke. The needle is clamped to a segment 28 projecting from a hub 30 forming part of a slide moving backward and forward in the direction of feed. The awl is clamped to a segment 32 projecting from a hub mounted on the hub 30. A needle guide 38 is also mounted on the hub 30. Back and forth movements are imparted to the slide carrying the hub 30 by levers 42, 44 connected together by a link 48. The lever 44 has a rear extension pivoted to a link 50 connected by a block and curved slot to a cam actuated by an arm 52. Oscillating work penetrating and retracting movements are imparted to the needle by a cam groove formed in one face of a spiral gear 54 on the camshaft 14 through a series of levers and links. Similar movements are imparted to the awl by a cam groove in the opposite face of the gear 54. The slide carrying the needle and awl is moved in a direction to feed the work while either or both are in the work and is moved in the opposite direction while both are out of the work. To avoid jerky feeding, means are provided for continuing the feed of the work while the needle and awl are out of the work. To this end, the channel guide 10 is mounted in a separate slide comprising a yoke shaped frame, Fig. 4, to which reciprocating movements are imparted by cam actuated connections. These reciprocating movements are timed with relation to the feed movements of the needle and awl to produce a continuous and uniform feed. Work supports and guides.-The position of the work in the machine is determined by a channel guide 10, so that the length of loop drawn through the work by the needle measured from the welt side varies with the thickness of the work. A welt guide 104 is also provided. It consists of a loop through which the welt passes and is yieldably held against the shoe during sewing. The work is also guided and supported by a rest 118 on the forward end of a curved slide 120. The welt guide carrier has teeth 124 engaging a pawl to prevent backward movement of the work holding means. Trimming or cutting.-The welt is severed after the sewing operation by mechanism comprising gripping jaws 148, 150 on a slide 154, and a severing knife 152 on a separate slide 156, Fig. 22. To prevent the knife from severing the thread, the gripper 148 is recessed and the knife 152 arranged to pass beneath the thread. Driving.-The driving mechanism comprises a gear 206 meshing with a gear 54 on the main cam shaft. The gear 206 is splined on a vertical shaft 208 provided on the driven part 210 of the main friction clutch. The driving part of the clutch 212 is carried by a vertical shaft 214 driven from a motor in the base of the machine. A spring tends to separate the members of the driving clutch and a foot treadle is actuated to cause the clutch to engage. The stopping mechanism comprises a relatively low speed driving mechanism which operates after the main driving clutch has been thrown out to slow down the driving shaft and then reverse it to final stopping position. This low speed mechanism comprises a gear 226 integral with the gear 194 rotating loosely on the cam shaft 14 and meshing with the gear 228 on the end of an inclined vertical shaft 230 carrying a bevel gear meshing with a bevel gear on the motor shaft 214. A follower 258 is provided to stop the cam shaft with certainty at a predetermined position. An arm 260 swings on stopping the machine to retract the welt guide and release the thread tension. Tension devices.-The thread tension is controlled by a wheel 16 of usual construction having a brake member 282 pivoted on an arm of a bell crank 284. A compression spring 288 acting on an adjustable nut on the bolt 286 forces the brake against the drum 280 to produce the required tension. The brake is released during the stopping of the machine by a rod 290 operated by the lever 260.