Patent GB-190902093-A (GB)
Title: Improvements in or relating to Sewing Machines.
Inventor: PLANT GUSTAVE THOMAS
IPC: D05B15/00
Filed: 1909-01-28
Granted: 1910-01-27
Abstract: 2093. Plant, T. G. Jan. 28. Boot - sole sewi n g - m a c h i n e s ; trimming or cutting; thread-cutters a n d endholders. - Relates to welt and thread cutting and endholding devices in boot-sole sewing- machines. A bar 51 slidingly mounted in the machine f r a m e carries a h e a d upon which are mounted upper and lower clamping-heads 59, 68, having at their forward ends co-operating welt and thread clamping- jaws 67, 71. These jaws are normally held open by a spring 80. A projection on the head 59 contacts with the rear of the head 68 so that the jaws move oppositely in closing. On the side of the machine frame is pivoted an actuator plate 38, which is linked to the head 59 by means of two links, one 86 pivoted to the plate and the other to the head, and each slotted to embrace the pin of the other. These links are kept in extended relation by a spring 93. On the forward end of the link 86 is a welt-cutting blade 89 which runs in a groove 92, Fig. 10, in the lower cutting-head 68. When the actuator plate is rotated, by means of its special treadle, the links 84, 86 acting together move the head 52 and the clamping - parts forward into operative position as determined by a stop 52<1> on the rear of the rod 51. Thereafter, the links rotate the head 59, which pressing upon the rear 78 of the clamping-head 68 commences the closing of the jaws. This is completed by a bowl on the actuator plate, which passes under and forces up the cam-end 61 of a resilient arm 60 attached to the head 59. When the head 59 is arrested by the completion of the clamping movement, the pin 85 on the actuator plate, as it continues to move, carries with it, in opposition to the spring 93, the link 86, and the cutter 89 upon it severs the welt. To ensure the proper positioning of the welt at the commencement of the next welting operation, the jaws are so shaped as to bend the welt as indicated in Fig. 7. A guide 75 is attached to the lower clamping-head to guide the welt as the clamping-jaws are moved to engage it. A thread-cutter 73 is secured to the side of the upper jaw, and the thread is cut when the operator draws the boot towards him. The thread is clamped with the welt between the jaws 67, 71. These jaws are normally held open position by a detent 96, which is released during the first rotation of the cam shaft in the next operation. In the return of the parts to their inoperative positions, a cam-plate 104, Fig. 4, contacts with a bowl 63 on a rigid arm 62<1> attached to the head 59 and rotates the latter, thus ensuring the opening of the clamping-jaws. A pivoted plate 118 prevents the operation of the clamping and cutting devices until the backgauge is in its rear position, and thereafter prevents the movement of the back-gauge forwards until the detent 96 is retracted and the actuator and co-operating parts are returned by the springs acting on the treadle-rod. The plate 118 is operated by a pin 121 on the stop 52<1>, which contacts with arms 119, 120. When the back-gauge is in its forward position, an arm 122 of the plate 118 is held by a pin 117 on the arm 114 attached to the back-gauge slide. The arm 123 at the same time bears upon a bowl on the actuator and so prevents the movement of the actuator. When the backward movement of the back-gauge frees the arm 122, the movement of the actuator, by means of the stop 52<1>, which contacts with the arm 120, lowers the arm 122 into a position in which it acts as a stop to prevent forward movement of the back-gauge. The thread tension, which may be of the kind described in Specification 18,423/08, is released, when the actuator plate is moved to clamping position, by means of a rod which is linked by parts 125, 127 to the actuator plate.