Patent GB-646673-A (GB)
Title: Improvements in or relating to copying machines
IPC: B23Q35/20
Filed: 1948-10-26
Abstract: 646,673. Copying-milling machines. COOKE, E. A., PEARSON, R., and KAPELLA, Ltd. Oct. 26, 1948, No. 27808. [Class 83 (iii)] [Also in Group XX] A copying-machine employing a rotary milling or other tool comprises a pantograph a<SP>1</SP>, a2, a<SP>3</SP>, a<SP>4</SP>, Fig. 2, which is mounted on a fixed pivot a and carries a tracer support 31 so that movements of the tracer over the master to be copied are reproduced in the desired ratio by the reproduction point g of the pantograph and the axes of the fixed pivot a, reproduction point g, and tracer support 31 all lie in the same plane (i.e. the primary pantograph plane), and a tool support 41 which, in addition to its connection with the reproduction point, is connected to a fixed part 1 by a duplex parallogram linkage whereby any given plane of the tool support will for all translational positions be maintained parallel to a plane fixed in space. The pivoted connections e, f of the link a<SP>4</SP> are carried by slides 16, 17 which are, respectively, adjustable along the link a<SP>3</SP> and a guide 18 on the link a<SP>1</SP>. The pivot g is supported by a slide 19 adjustable along the link a<SP>4</SP> and is coupled to a slide 20 which is adjustable along a slide bar 21 pivotally connected to a frame 22 for the tool-holder or slide 41; the frame 22 is additionally supported by two interconnected links k<SP>1</SP>, k<SP>3</SP> which are pivoted on the pivot a and frame 22. The duplex parallelogram linkage comprises two links p<SP>1</SP>, ql, Fig. 2, which at one end are connected to opposite sides of the frame 22 and at the other end are joined by a secondary link which is pivoted centrally on another secondary link connected between two links x<SP>1</SP>, y<SP>1</SP> mounted on fixed pivots 12, 13 ; as shown in Fig. 5, the links x<SP>1</SP>, y<SP>1</SP> are pivoted to a ring m<SP>4</SP> adjustable relatively to a ring m<SP>5</SP> to which the links pl, q<SP>1</SP> are pivotally connected. The tool slide 43, Fig. 3, moves in vertical guides 40 in the frame 22, being urged upwardly by one or more springs, and the spindle 27, Fig. 4, of the tracer is slidable in guides 26 in the arm a<SP>2</SP>, being provided at the upper end with a plunger 32 slidable in a cylinder 31<SP>1</SP> in the tracer support. Rollers 35, 38 mounted, respectively, in the cylinder 31 and plunger 32 are caused by springs 36 to engage the upper and lower surfaces of a beam 14 which is pivoted at one end along vertical and horizontal axes 11, 25. The underface of the beam is also engaged by a roller 43 mounted on the head 42 of the tool slide 41 so as to be rotatable about a vertical axis. If desired, the vertical pivot 11 of the beam 14 may coincide with the pantograph axis a. The tool 44 carries a pulley 45, Fig. 3, which is driven by a belt 47 from motor-driven reduction gearing 48. In operation, the slides 16, 17, 19 are adjusted to give the desired pantograph ratio-and the rings m<SP>4</SP>, m<SP>5</SP>, Fig. 5, are clamped together after setting the angle between the secondary links of the duplex parallelogram so that the vertical plane of the longitudinal axis of the slide 21 is parallel to the vertical plane containing the axes a, 11. For operation at unity ratio, the slide 19 is released from the slide 20, and the tool and tracer supports are connected by a rigid coupling. In an alternative arrangement which' does not permit of unity reproduction, the slide 19 is permanently coupled to the slide 20, and the slide bar 21 or an extension thereof extends beyond the primary pantograph plane to the tool frame 22. In another arrangement, the tool axis h, Fig. 2, is not displaced from the primary pantograph plane, and the connection between the reproduction point g and the slide 20 is detachable so that the tool and tracer supports may be directly connected for unity reproduction. The pantograph mechanism may be modified (Fig. 8, not shown), by arranging for the link a<SP>3</SP> to be adjustable along guides on the links a<SP>2</SP>, a' and to carry a block which co-operates with a guide plate on the tool frame ; the block may be released from the tool frame when it is desired to couple the tool and tracer supports for unity reproduction. An alternative duplex parallelogram linkage comprises links x<SP>1</SP>, y<SP>1</SP>, Fig. 9, with two links p<SP>1</SP>, q<SP>1</SP> pivoted to the links x<SP>1</SP>, y<SP>1</SP> at n<SP>1</SP>, n<SP>2</SP> and connected by a tie-link p<SP>2</SP>; the link x<SP>1</SP> is pivoted at the pantograph axis a and the link p<SP>2</SP> extends to the tool axis H. For two-dimensional copying, the beam 14 is omitted, and the tool slide 41 is locked to the guides 40. The Provisional Specification describes also a modified form of the arrangement shown in Fig. 9, wherein the link p<SP>2</SP> is of triangular form in plan and carries a longitudinal guide to which a slide block connected at the reproduction point G may be coupled in desired position. The point G is carried by the pantograph link A<SP>3</SP> which is adjustable along both the links A<SP>3</SP>, A<SP>4</SP> and its own axis. The tool support is movable in vertical guides in the wide end of the link p<SP>2</SP>. Specification 418,135 is referred to.