Patent GB-893966-A (GB)
Title: Equipment for the automatic indication of measuring scale settings in machine tools
Filed: 1959-11-16
Abstract: 893,966. Controlling machine tools. HENSOLDT & SOHNE, OPTISCHE WERKE A.G., M. Nov. 16, 1959 [Nov. 19, 1958; Oct. 31, 1959], No. 38707/59. Class 83 (3). [Also in Group XXXVIII] In an arrangement for the automatic indication of measuring scale settings, particularly for machine tools, in which two automatic indicating devices of known form operating on different principles are utilized to derive the required indication, one of the indicating devices preferably comprising a photo-electric cell scanning the graduations of the measuring scale, the devices are arranged to operate so that each provides a check on the indication furnished by the other. If the two devices provide different indications, an alarm signal is given. In the diagrammatic arrangement, Fig. 1, impulses from an audio frequency generator 11 are passed to a sound head T associated with a ferromagnetic scale member 1 carrying divisions 2 which via amplifier 14 and rectifier 15 produce positive pulses p fed to the counting mechanism 16. Pulses from a generator 17 and photo-electric head F produce, in response to the markings 2, negative pulses p<SP>1</SP> equal in amplitude to the pulses p, fed to a discriminating circuit 20 to which the pulses p are also fed. When the pulses p, p<SP>1</SP> occur simultaneously the output of the circuit 20 is zero but in response to a pulse produced by solely one of the devices T, F, the output of the circuit 20 illuminates a warning lamp 21. A balanced bridge arrangement for the magnetic head T, Fig. 2 (not shown), comprises two pickup heads associated with two portions of a transverse line on the member 1, the scale divisions extending approximately for one half the width of the member 1. A modified pickup head, Fig. 3 (not shown), is operated as a transformer. An arrangement for automatically moving a slide to a position corresponding to a predetermined setting is described in connection with Figs. 4, 5, 6. The slide 101 carrying scale divisions 120 is coupled to a rack 102 engaged by a gear-wheel 161 driven by a motor 160. The desired setting is set up by knobs 105<SP>111</SP> in centimetres and hundredths on the two sections 105<SP>1</SP>, 105<SP>11</SP> of a counter 105 actuated photo-electrically by the centimetre divisions 120 of the scale 101 and by a luminous spot 140 in connection with a disc 143 having one hundred circumferential apertures, a mirror 146 displaced to the position 146<SP>1</SP>, lens 130, carried by a traversable member 140, surface 135 of a reflecting member 134 and the operating photo-cell 132. When the disc 143 has been rotated to correspond with the hundredths part of the setting as registered, the bracket 141 carrying the lens 130 is correspondingly moved by the shaft of micrometer screw 142, the portion 105<SP>11</SP> of the counter 105 is brought to the zero position and by means of a circuit 123 the motor 160 is set into operation and the mirror 146 withdrawn to the position shown in full lines. The scale 101 together with the rack 102 is now moved, and the detection of the centimetre divisions actuates the cell 132 to operate the centimetre recording part 105<SP>1</SP> of the counter 105. When the section 105 approaches the zero position a device 162 operates to retard the motor 160 and a circuit 157 is connected so that when the light impulse from the appropriate subdivision 120<SP>1</SP> appears beneath the lens 130 and by lenses 132<SP>1</SP>, 152 is passed to the photo-cells 153 and 154, the motor 160 is instantaneously brought to a stop. During the motion of the rack 102, a wheel 110 is rotated and periodically closes contacts 113 which through a generator 116 operate the mechanical counter 106 so that the reading at the end of the movement of the slide 101 should correspond with the predetermined figures originally set up on the photo-electrically actuated counter 105.