Patent GB-172689-A (GB)
Title: Improvements in or relating to machines for measuring, gauging, or the like
IPC: G01B5/16
Filed: 1920-08-12
Abstract: 172,689. Wickman, A. C. Aug. 12, 1920. Linear-dimension gauges; surface and outline gauges.-A machine for measuring and testing linear dimensions, for example external and internal diameters of bars, ring gauges, &c., comprises a pair of anvils for supporting the work, one 7 being carried by a stationary support and controlled by a micrometer 8, and the other 6 being mounted on a sliding carriage 5 urged towards the anvil 7 by a depending weight. A stylus 4 mounted upon a resilient plate or blade 15 and connected by a multiplying system of levers with an optical indicating arrangement is .employed for the purpose of ensuring a constant position for the carriage when external measurements are in progress, and this stylus may be readily interchanged for others designed for testing by direct contact the diameters of internal screws. The carriage 5 carries a pair of anvils 9 for supporting either the work (for internal gauging) or a grooved rod to be felt by the stylus, and is also provided with a cross slide 11. The carriage 5 is connected by a cord 50, Fig. 17, with a weight 49 fitted with a baffle-plate 55 and working in a cylinder 52 containing oil or glycerine for damping purposes; the plate and the weight have relatively staggered apertures 53, 54. The stylus 4 is removably mounted in a head 14 - secured to the upper edge of the spring plate 15 and attached to one arm of a lever 16 pivoted at 17. A second lever 20, Fig. 10, pivoted at 21 is connected by a distance-bar 24, Fig. 13, with the lever 16 and carries at its farther end a wire for casting a shadow upon a screen 34. The levers 16, 20 are kept in engagement with the distance-bar 24 by a pair of springs 23 secured to yokes 26 capable of rocking on the brackets 25 attached to the levers. The movements of the levers are damped by means of vanes 43, 45 mounted on their free ends and moving in dashpots containing liquids of differing viscosities. The index shadow is thrown upon the screen 34 by a beam of light from lamp 27 passing through lenses 28, 30 to a mirror at the top of the casing' 31<1> and thence back to a mirror 33. The micrometer device, Fig. 11, comprises a spoked wheel 64 carrying a removable or circularly adjustable graduated rim 63 and secured upon a sleeve 65 provided with a hand-wheel and fixed to the screwed bolt 62 bearing against the anvil 7. The bolt works in a stationary nut 66 and also in a nut 67 which is slidable within an extension of the nut 66 and is pressed outwardly by a spring 68.' A vernier-index arm 60 is pivotally mounted upon the anvil and its extension 70 bears upon a cam-plate 72 which may be shaped so as to compensate for any irregularities in the micrometer screw-threads. In order to test the length of a bar', a standard bar is first placed between the anvils 6, 7 and the stylus is engaged with the groove 10 in the feeling-rod 10<1> by moving the slide 11 towards the stylus. The micrometer is next adjusted until the shadow indicates zero upon the screen and a stop 58 on the frame is shifted so as to be nearly in contact with a stop 56 on the carriage 5. The graduated rim 63 on the micrometer wheel is then slipped round to show zero and secured by the clamping-screws 69. The standard bar is now removed from the anvils 6, 7 and the bar to be examined substituted for it. If the shadow index no longer shows zero, the micrometer may be turned forward or backward to make it do so. and thus the deviation from the standard length may be measured. When using the apparatus for measuring say the internal diameter of a ring gauge, the latter is mounted upon the slide 11 by means of a plug and a work-holder 12, and is engaged at one side by a stylus, (such as those shown in Figs. 19 and 21) which is shaped in accordance with the kind of diameter required. A plate 37, Fig. 10, having a coned aperture to fit over a pin on the lever 16 and controlled by opposing springs 35 is lowered upon the pin so as to impose a centralizing control upon the levers and index. The micrometer is adjusted to bring the index to one side of zero and' its scale then zeroized. A bar approximating or equal in length to the diameter to be gauged is now inserted between the anvils 6, 7, the stylus being thereby caused to engage with the opposite end of the diameter and the reading is again taken with the index displaced to the same extent on the other side of zero. In order to test whether the stylus points occupy their correct relative positions or to calibrate them, the device shown in Fig. 22 is employed. This consists of two pairs of chamfered discs 84 mounted in a head-piece 82 adapted to be inserted in the holder 12 and between the anvils 9. The shape of the virtual screw-threads formed by the chamfers of the discs may be tested in the known way, and one pair of discs may be removed from the plane of the other to the extent of half the pitch of the screw-thread concerned by inserting a washer 86 of the necessary thickness. The machine may be used for testing external screwthreads in the usual manner by making the anvils 6, 7 abut each other as by arranging the micrometer and anvil 7 so that the latter can be moved up to the anvil 6. Specification 133,416, [Class 12 (i), Bearings &c.], is referred to.