Patent GB-664717-A (GB)
Title: A method of and means for visually indicating a machining operation of a machine-tool
Inventor: WHITEHHEAD FREDERICK WILLIAM
IPC: B23Q15/22
Filed: 1949-06-14
Abstract: 664,717. Lathes. BRISTOL AEROPLANE CO., Ltd., and HERBERT, Ltd., A. May 17, 1950 [June 14, 1949], No. 15767/49. Class 83 (iii). The movement of a tool-slide 14, Fig. 1, in directions transverse to one another during a particular machining operation in a machinetool is magnified and indicated visually on a screen 35, fixed to the bed of the machine, by a light - transmitting graticule mounted on the slide for co-operation with a stationary source of light 30 when the cutting-tool is in the operative position in order that the light rays may be transmitted through the graticule and magnifying means to project indicating markings 40, 41, Fig. 7, on the graticule and related to the desired feed of the tool on to the screen where they co-operate with screen-markings 38, 39 which are related to the particular machining operation. As applied to a lathe, Fig. 1, for machining cylindrical grooves 23 in compressor casings 20, in which the latter are rotated by a headstock 21 adapted to be swivelled to bring the inclined wall 22 of the casing into parallel relationship with the axis of a boring bar 16, the position of the slide 14 may be indicated on the screen for facing the end of the casing 20 by a tool 46, for boring the casing by a tool 29, Fig. 7, fixed to the end of the bar 16, and for rough and finished turning the grooves 23. The turning-tools 52, which may be equal in number to the number of grooves 23 to be cut, are mounted around the circumference of the bar 16 so as to be operative one at a time and are indexed into the operative position by releasing clamps 27,. 27a on the tool-head 15 and rotating the bar by a wheel 26. Alternatively, each tool 52 may cut two grooves 23 by repositioning the bar 16 after the first series of grooves have been cut. The slide 14, which is mounted to slide in a direction parallel to the inclined axis of the casing 20 on a cross-slide 13 supported on a saddle 12 carried by rails 11 on the bed of the machine, supports two similar holders B, B<SP>1</SP> for composite graticules and a third holder A for a further graticule, the holders B, B<SP>1</SP> being of opposite hand to permit of close spacing. The bar 16 is positioned for boring by traversing the saddle 12 to bring the graticule in the holder A beneath the source of light 30, which may be a lamp, and aligning V-markings 40, 41, Fig. 7, projected from the graticule by a lens and projector 33 on to the vertical screen 35, with the markings 38, 39 on the screen. In connection with the graticule in the holder A, the mark 38 on the screen refers to a position of the boring-tool just clear of the end of the casing, and the mark 39, which is inclined to the horizontal at the same angle as that between the axis of the casing 20 and the rails 11, refers to a position of the tool to cut to the required bore. The boring operation is then carried out by traversing the saddle 12 which causes the holder A to pass from beneath the source of light 30. The composite graticule, Fig. 3, in each of the holders B, B<SP>1</SP> comprises an upper slide 55 having a light-transmitting disc 64 bearing a V-mark 42, and a lower slide 59 with a lighttransmitting disc bearing markings 40a, 41a, 43 and 44, the slides being locked together by a clamp 83 after adjustment. Springs 56 urge the slide 55 against adjustable stops 57, carried by projections 58 from the slide 59, and against a pin 69 which can be adjusted roughly by a grub-screw 81 and locating-nut 82, and finely by a micrometer-head 75. The slide 59 is also spring-pressed against adjusting stops 62 on the casing of the holder and against a bell-crank lever adjustable by a screw 66 to cause movement of the slide in a direction to the left as viewed in Fig. 3. For the end-facing operation, the graticule B<SP>1</SP> is brought beneath the source of light 30 and the graticule markings 40a, 41a aligned with the screen markings 38, 39, as shown in Fig. 6, which is a view of one of the composite graticules having the screen markings projected thereon. The saddle remains stationary during the facing operation which is carried out by movement of a tool-slide 47. The bar 16 is positioned for rough-turning the grooves 23 by traversing the saddle 12 until the markings 40a, 41a on the graticule B are bisected by the screen markings 38, 39. The cross-slide 13 is then caused to feed the turning- tool into the rotating work-piece, this operation being indicated visually on the screen by movement of the graticule marking 44 towards the stationary screen marking 39, and terminated when the marking 39 bisects the marking 44. After withdrawing the cross-slide 13 until the marking 41a is bisected by the screen line 39, the bar may be indexed and the operation repeated for each tool station on the bar. A second series of grooves may be cut after the bar 16 has been repositioned by traversing the saddle 12 until the markings 40a, 41a of the graticule B<SP>1</SP> are bisected by the screen lines 38, 39. For finish-turning the grooves, the roughing tools are replaced in the bar by the finishing tools 52, Fig. 10, which are fed into the workpiece until the marking 44 is again bisected by the screen line 39. The grooves are then turned to the required width by traversing the slide 14 until the points of intersection of the markings 42, 43 are coincident with the points of intersection of the screen lines 38, 39. Wear across the width of the tools 52 is compensated by micrometer-head adjustment of the graticule marking 42 relatively to the other markings on the graticule. As illustrated in Fig. 6, this adjustment increases the distance 53 on the screen from the reference line 38 to the point of intersection of the markings 42, 43 by a distance 70. The operation of the micrometerhead 75 is such that when it is kept adjusted to read the worn width of the tool, the width of the groove cut will remain constant at the desired value. Specification 638,945 is referred to.