Patent GB-312978-A (GB)
Title: Improvements in or relating to copying lathes
IPC: B23Q35/10
Filed: 1927-12-03
Abstract: 312,978. British United Shoe Machinery Co., Ltd., (United Shoe Machinery Corporation). Dec. 3, 1927. Divided on 312,946. Lathes.-In a copying lathe for producing boot and shoe lasts, width grading mechanism is' provided which is capable of cyclic variations in timed relation with the rotation of the work, so that a last may be produced which is identical with the pattern on part of its circumference. (such as the sole) and is proportionately larger or smaller than the pattern on the remainder of its circumference. The degree of width grading produced is not affected by change of the shape or dimensions of the model. The lathe, which is described in detail in Specification 312,946, comprises a pattern-follower carriage 20 and a cutter carriage 22 moved in opposite directions by a right and left hand screw 23. The pattern 12 and work 14 are mounted at opposite ends of a headstock-spindle 16 carried by a swinging frame 10, the spindle being rotated by gearing 40, 38 from a gear 32 concentric with the axis 34 about which the frame 10 swings. The gear 32 is driven by gears 28, 30 from a pinion on the end of the main driving shaft 24. The pattern follower 21 is carried by the grading slide 44 which is capable of movement in the stationary frame of the machine transversely to the axis of rotation of the work and is given this movement to alter the scale of reproduction by means of a link 48 pivoted thereto at 50 and having a roller 52 engaging a fan-board 54. The fan-board is connected by a link 58, Fig. 1, with the swinging frame 10 so as to partake of all its oscillatory movements and has an operative surface which is part of a circle described about the pivot 50 as centre. In the neutral position of the grading mechanism (i.e., when the axis of the model and work is tangential to the periphery of the cutter) the fan-board is concentric with the pivot 50 and the link 48 may be set to the desired grading position on the fan-board without displacing the follower slide 44, by means of a link 74. This link is pivoted at its lower end to a block 72 slidable in an arcuate slot 70 of a member pivoted at 76 and provided with an arm 68 having a roller 66 kept in contact with a cam 64 by a spring. The cam is rotated at the same speed as the work by a gear 62 engaging an elongated pinion 60 on the driving shaft 24, and the block 72 may be adjusted along the slot 70 by means of a link 78 pivoted to an arm 80 actuated by a toothed segment 82 in engagement with a worm 84 on a hand-operated shaft 86. The radius of the arcuate slot 70 is equal to the length of the Link 74 so that in one position of the arm 68 the slot will be concentric with the upper pivot 75 of the link 74, and when in this position no width grading can take place, i.e. the work will be produced to the same scale as the model. In operation, the block 72 is moved by the shaft 86 to a point in the slot 70 to produce the required width of grading and while the work is rotating, the raised concentric portion of the cam 64 rocks the slot to its concentric position and thus causes the grading to be suspended for a portion of each revolution of the work, while for the remainder of the revolution the lower concentric portion of the cam oscillates the slot to the position shown in Fig. 2 and allows the normal grading to become effective. For grading a series of lasts' having different width but the same insole pattern the block 72 is set for each width and the cam 64 ensures the insoles being the same width. For ordinary width grading without the cyclic variation the cam 64 is replaced by a circular cam having a radius which is approximately the mean of the larger and smaller radii of the cam 64. The remainder of the grading mechanism shown, which corrects the position of the pattern follower 21, is described in Specification 312,946. Specifications 27978/09 and 143,622 also are referred to.