Patent GB-527636-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B15/00
Filed: 1939-04-06
Abstract: 527,636. Sewing-machines. DEL-MAC SHOE PROCESS CORPORATION. April 6, 1939, No. 10731. Convention date, April 7, 1938. Addition to 488,855. [Class 112] In a machine for stitching the upper to the sole of a turnshoe in the manner described in Specification 488,855 and having a work-feeding straight hooked needle 24, Fig. 1, work supports 20, 22, 38, horn 40, presser-foot 26, upper guard 42, and awl 28, Fig. 9, as described in that Specification, the horn 40 is moved a fixed slight distance away from the work to reduce the pressure during the feeding operation while maintaining its guiding effect and is locked in position during the operation of the needle and awl, the upper guard 42 (which is modified) is lifted a small distance during the feeding operation, and the presser-foot has modified locking means and is released slightly before the end of the needle stroke so that the work is slightly lifted from the supports 20, 22 during feeding. The upper guard and horn are retracted from the work when the presser-foot is lifted by the usual means at the end of a seam. The presser-foot is biased towards the work by a relatively light leaf spring 64, and is lifted during the feeding operation by an arm 68 on a rock shaft 66 through means as described in Specification 488,855. The presserfoot is locked in engagement with the work by a pawl 88, Fig. 6, engaging a series of teeth 86 on a slide 80 which is connected to a pin 82 on a bracket 84, Fig. 1, clamped on the presser-bar 62 ; the pawl is pivoted at 90 and is actuated by the arm 68 through a contact screw 98 carried by a tail on the pawl. The pawl is also actuated to permit lifting of the presser-foot by the usual treadle-operated lever 102, by a member 104 pivoted on the pin 82 and provided with a cam surface for engagement by an arm 108 on the lever 102. The horn 40, Fig. 1, is pivoted on a pin 110 adjustable vertically in a bracket 118 which is adjustable horizontally on an arm 112 pivoted at 114. The horn is controlled by a sliding bar 122 connected to the arm 112 by a link 126 which forms a toggle with the arm 112 ; a spring 128 engaging a lug on the bar 122 presses the horn against the work. The horn is moved a predetermined small distance from its work-holding position during feeding by an arm 148, Fig. 7, on a rock-shaft 150 actuated by a block on the awl-bar engaging another arm on the shaft, the arm 148 engaging one edge of a tilting-ring clamp 140 surrounding the bar 122; the clamp ring 140 is pressed downwards by springs 142. This movement of the horn away from the work takes place before the feed starts, and preferably slightly in advance of the presser-foot lifting, and the horn engages the work again before the presser-foot to ensure correct positioning of the work. The horn is also retractedby the presser-bar lifting lever 102 by means of a lug 196 on the bar 122 engaging the arm 108. The upper guard 42, Fig. 9, formed on the lower end of a slide 156, has a recess 166 to clear the needle and a flange 168 with a downward projection 170 which engages the edge of the shoe sole, even in the retracted position shown, and clears loose parts of the shoe lining in advance of the sewing point. The upper guard 42 is moved a predetermined short distance away from the work during feeding, this movement starting only after that of the horn and presserfoot, and is re-engaged with the work before the horn and presser-foot. The guard is pressed downwards by an arm 172 of a torsion spring arranged on the lower end of the bar 122, and the movement referred to above is produced by a cam member 176, pivoted on the pin 114 and working in a slot in the slide 156, actuated against a spring 178 by a lug 189 on the awl-bar 60. The guard is lifted by the presser-lifting lever 102 by means of a lug 200 on the bar 122 engaging under an offset upper end of the slide 156.