Patent GB-656799-A (GB)
IPC: G01B5/20
Abstract: 656,799. Gauging-apparatus; recording- apparatus. MEASURING MACHINES, Inc. Aug. 23, 1948, No. 22180. Convention date, April 13. [Classes 106 (ii) and 106 (iv)] Apparatus for making and recording profile measurements of an object comprises a movable feeler, means for causing the feeler to engage different regions of the object and control the direction of rays of light on to a sensitized photographic film, and means for subjecting the film at the same time to illuminating rays spaced to photographically produce a scale on the film. The article to be gauged, e.g. a turbine blade A, Figs. 1 and 2, is fixed to a clamp 17 mounted on a table 16 rotatably adjustable by micrometer screws 30, 31 which co-operate with upstanding pins 32, 33. The table 16 is carried by a slide 15 laterally moved along a slide 12, as described later, in step-bystep manner by a screw 20 rotated by a motor 25. The slide 12 is transversely adjustable on a vertically adjustable block 11. Feelers 42 are carried by arms 40 pivotally mounted by ball bearings 100, 101, Fig. 3, on respective spindles 41. Overlapping permanent magnets 125, 126, carried by the arms 40 respectively urge the feelers 42 towards each other into engagement with opposed faces of the work - piece A. Each arm 40 carries a rack 43, Figs. 1, 6 and 7, the teeth of which engage a pinion 110 rigidly mounted on a sleeve 120 on a vertical shaft 112 journalled in jewel bearings carried by a bracket 116 supported by the base 10. Each sleeve 120 carries a disc 121 which supports a forked plate 122 on which a mirror 45 is mounted. The movements of the feelers 42 as the workpiece passes between them are thereby transmitted to the respective mirrors 45. A pair of springs 128 press on the discs 121 respectively to prevent backlash in the gear train between the racks 43 and the pinions 110. A source of light 50 periodically directs rays through focusing lenses 51 to the mirrors 45 from which reflected beams 53 are directed through a slot 65 in a housing 64 containing a sensitized paper or film B unwound in stepby-step manner, as described later, by a motor 70, Fig. 8, from a roll 60. Two profile series of dots X and Y are thereby produced on the paper or film, Fig. 10. A second source of light 66 operated as the paper B is moving also directs a beam of light 54 through the slot 65 on to the sensitized paper but this beam is broken by passage through a curved comb 67, Figs. 2 and 9, so that it produces on the paper a series of dashes in rows a, b, c..., Fig. 10. The spacing of the slots in the comb 67 is fixed so that the " dashes " on the paper form in effect a scale against which the distance between corresponding pairs of " dots " on the curves X and Y may be measured. Every tenth slot in the comb 67 is widened to produce a thicker vertical column of " dashes " and at every fourth successive step or feed of the paper 60 a resistance is cut out from the circuit of the lamp 66, the light of which is thus intensified and so every fourth horizontal row of " dashes " is heavier than those of the preceding three rows. Before testing or gauging a new workpiece a lever 185, Fig. 15, is moved downwardly, whereupon a pawl 186 rotates the paper feed ratchet 90 one step. At the same time a frame 182 is pivoted by a link 187 against the pressure of a spring 183 to move a roller 181 away from a slot 180 in the housing 64 to a position over the slot 65, the daylight passing through the slot 180 produces a datum line Z on the paper strip. The motor 70, Fig. 8, rotates continuously and effects through an eccentric 95 vertical movement of a link 93 which carries a pawl 92, whereby step-bystep movement is given to the ratchet 90 and the paper feed rollers 61, 62. The motor 70 rotates a cam 96 which operates the switches 97, 98, 99 to control respectively the starting of the motor 25 which controls the slide 12, the lighting of the lamp 66 and the lighting of the lamp 50. The motor 25 is stopped when a cam 170 rotated thereby opens a switch Q. A cam 165 carried by the shaft 91 of the ratchet 90 effects closure of a switch 164 during every fourth step of the ratchet 90 to short circuit the resistance R in the circuit of the lamp 66 for the above-mentioned purpose. In a modification the feeler carrying levers are mounted on a common pivot and each mirror is carried by a bracket so as to be tiltably adjustable.