Patent GB-499327-A (GB)
Title: Improvements in or relating to shoe sewing machines
IPC: D05B15/00
Filed: 1937-07-22
Abstract: 499,327. Sewing-machines. UNITED SHOE MACHINERY CORPORATION. July 22, 1937, No. 20282. Convention date, July 25, 1936. [Class 112] A welt sewing-machine of the type described in Specification 22382/09, [Class 112], for uniting a welt, insole and upper by stitches, is provided with means for slashing the sewing rib in timed relation to the sewing, to render the completed shoe more pliable. In the embodiment shown, the curved hooked needle 20, awl 22, looper 24, take-up 26, and feed slide 42 are operated and constructed as described in Specification 22382 /09. The slashing knife 70 is supported coaxially with the awl on the feed slide and is spaced from the awl about half a stitch length and operates in the line of feed in advance of the needle. The knife 70 may have a broad cutting edge to slash through the whole of the rib, Fig. 8, or may be replaced by a knife 71, Fig. 9, with a short cutting edge so as only to cut through the lower part of the rib. In the first case, both the main rib and marginal rib are slashed. In the second case, the marginal rib is bent back as shown at 73 and is uncut. Assuming the machine is in a condition in which the slashing mechanism is inoperative and the latch 74 free to move upwards under the influence of the spring 80, Fig. 14, the retracting movement of the needle 20 and its segment 34 will cause the latch 74 to ride idly over the plate 78. As the needle segment continues its retraction to draw in the last completed stitch, the pivot pin 54 will engage with the rear side of the knife segment 72 and impart to it an idle movement insufficient to bring the knife 70 into contact with the work. For retracting the knife, a tension spring 84 is connected to an eye 86 in the segment 72 and to an L-shaped plate 88 secured to the feed slide 42. To ensure that the knife is retracted with the awl an L-shaped member 90 with an extension 92 is provided on the awl segment 38 to engage the knife segment 72. The operation of the slashing mechanism is as follows. When the knee lever 112 is turned to the left the rocking lever 116 causes the control rod 124 to compress the spring 131 and rocks the control lever 108 in a counter clockwise direction and depresses the plunger 100 and foot 102 into operative engagement with the latch 74. The downward movement of the plunger 100 is only permitted as the feed slide is back-fed causing the cam surface 146 to ride out of engagement with and release the control lever 108. During this back-feed movement, the needle 20 advances to its limit through the work and the foot 102 of the plunger 100 comes into engagement with and depresses the latch 74, Fig. 14. The knife segment is held at the limit of its retracting movement in which the abutment 94 is engaged with the L-shaped stop plate 88 and the latch 74 is behind the locking member 78. As the needle segment rocks to retract the needle, the latch 74 enters into locking engagement with the member 78 so connecting the knife segment 72 and knife 70 so that a slashing cut is formed in the sewing rib as the needle segment completely retracts the needle. The advance of the feed slide then operates to engage the cam surface 146 with the control lever 108 to lift the plunger 100 and foot 102 out of the path of the needle segment. As the needle is again advanced through the work after completion of the feeding movement, the knife is retracted by the action of the spring 84, or by the engagement of the stop 92 with the segment 72. So long as the knee lever 112 is held in its operative position, this cycle of operations continues. When the lever is released the downward movement of the control rod 124 restores the slashing mechanism to inoperative position.