Patent GB-929551-A (GB)
Title: Improvements in change-speed indicators
IPC: B23Q1/00
Filed: 1959-01-06
Abstract: 929,551. Change-speed control. WILLIAM ASQUITH Ltd., and A. JOHNSON. Jan. 6, 1960 [Jan. 6, 1959], No. 467/59. Class 80 (2). Indicating means for pre-selecting gear mechanism comprises a dial bearing a series of markings corresponding to different ratios, a first indicating means showing on the dial a marking corresponding with a pre-selected ratio and a second indicating means showing on the dial the ratio which is established at any time, irrespective of any adjustment imparted to the first indicating means. In the form shown, two indicating means according to the invention are described applied to two preselector gears controlling the spindle speed and the rate of feed of a cutting machine tool. A dial 10, Fig. 1, made from translucent material, bears markings corresponding to the ratios in a spindle speed change-speed gear controlled by its rotation. A fixed indicating panel 11, carried by a casing 16, has a window aligned with the markings on the dial 10. Coaxial with the dial 10 is a ring 13 formed with a window 14 through which light from lamps 15, Fig. 4, can pass to illuminate one only of the ratio markings on the dial 10. The ring 13 is carried by a sleeve 23, Fig. 2, journalled on a bearing sleeve 19 and fast with a cam 24 coating with a vertically movable weight 25 guided on rods 26 so as to bias the dial 13 always to position its window 14 under the window in the fixed indicator 11. The dial 10 is fast with a knob 12 and a sleeve 18 journalled within thebearing sleeve 19, a diametral pin 30 passing through axial slots in the sleeve 18 and coating at its ends with teeth 31 in the outer sleeve 23. Accordingly, rotation of the knob 12 turns both the dial 10 and the ring 13. A gear 36 fast on the end of the sleeve 18 meshes a gear 37 rotating a ratio selecting valve 38. In the ratio established position, the window 14 in the ring 13 lies beneath the window in the fixed indicator 11, so that light from the lamps 15 passes therethrough and illuminates one of the markings on the dial 10. To preselect a new ratio, the knob 12 is turned and rotates both the dial 10 and the ring 13 together, the window 14 continuing to transmit light to the marking of the dial 10 indicating the ratio already established. When the appropriate marking on the dial 10 has been positioned beneath the fixed window 11 to indicate that the ratio has been pre-selected, a button 17, Fig. 2, is depressed and acts through its stem 29 to move the diametral pin 30 axially against the bias of a spring 32 out of engagement with the teeth 31 within the outer sleeve 23. The dial 10 and the ring 13 are now disconnected for relative rotation therebetween, so that the weight 25 acting on the heart-shaped cam 24 is able to turn the ring 13 and the window 14 back to their original position with respect to the indicator 11. At the same time, a snap-over switch, Fig. 3 (not shown), is actuated by the axial sliding of a flanged ring 44, effected on depression of the button 17, to establish the preselected ratio. The snap-over switch may operate as described in Specification 929,552 to cause a brake to be applied to the output of a driving electric motor and at the same time bring a governor switch into the motor power circuit, as well as de-energizing the electric lamps 15. When the speed of the driving motor falls to a predetermined speed for which the governor switch has been set, the latter causes energization of a solenoid-operated valve to supply fluid under pressure to the gear change mechanism and release the motor brake. The gear change mechanism is adjusted according to the setting of the selector valve, and current is restored to the driving motor when ratio establishment has been completed. Simultaneously, the lamps 15 are energized to illuminate the relevant marking of the dial 10 alignedwith the indicator frame 11 and the window 14 in the ring 13, which latter was restored to its zero position when the button 17 was depressed. The driving motor then continues to run at its normal speed, and the illumination provided by the lamps 15 indicates that establishment has been effected. The gear 36 fast upon the end of the sleeve 18 rotated by the knob 12 meshes the ratio selecting gear 37 and also with a gear 41 rotating a speed selector switch 43 in the circuit controlling the driving electric motor. In the form shown, the dial 10 indicates the spindle speed of the machine tool. A similar dial 10<SP>1</SP> and associated selector mechanism is provided within the casing 16 to control the ratios in gearing driving the feed mechanism. The feed selector mechanism is similar to that controlling the spindle drive gearing, with the exception that the ratio establishing button is omitted, establishment of pre-selected ratios in the feed drive gearing being effected simultaneously with depression of the button 17 within the spindle speed drive knob, this depression pivoting links 45, 48 acting upon a flange ring 44<SP>1</SP> to establish the selected ratio. As a modification, the mechanical connection between the diametral pin 30 and the teeth 31 within the sleeve 23 may be replaced by an electromagnetically controlled device disengaged on depression of the establishing button 17.