Patent GB-774654-A (GB)
Title: Gear analyzing apparatus
IPC: G02B21/00
Filed: 1955-09-02
Abstract: 774,654. Gear gauge optical-projection apparatus. PROJECTION GAGES, Inc. Sept. 2, 1955 [Sept. 20, 1954], No. 25304/55. Class 106(2). The accuracy of a gear is analysed by projecting an image of its teeth, together with that of a simulated theoretical rack with which it is engaged on to a calibrated screen. Projection apparatus.- The gear is held by supporting means on a work table 57, Fig. 6, and the images projected by a lamp 59, lenses 63, 65, 67, reflectors 69, 71, lenses 73, 75 and reflector 77 on to a screen 55. Another lamp 81 is mounted in the focal plane of lenses 65, 67 and illuminates the rear surface of the gear via a ring-shaped reflector 79. Gear supporting means, Figs. 3 and 5.-A T- shaped transverse carriage 95 runs on ballbearings 105 between longitudinal guide bars 91 secured to a base plate 89 bolted to the worktable 57. The carriage 95 is moved longitudinally by a rack housed on its undersurface and engaging with a spur gear whose shaft has a hand-knob 121, means being provided to eliminate back-lash and to lock the carriage with respect to the base-plate. Adjustable stops to limit the travel of the carriage are also provided. Rails 153 are sceured to the upper surface of the carriage 95 on which is guided by ball bearings 163 a second horizontal longitudinal carriage 155 which is constantly urged to the right as viewed in Fig. 5 by a compression spring located between it and the carriage, adjustable stop means being provided. The longitudinal carriage 155 supports a vertical dovetail guideway for a third carriage 223 movable in a vertical direction by a threaded shaft driven through bevel gearing by a handle 267. The vertical guideway supports a removable dial gauge 269 whose plunger 273 engages a rod 275 adjustably secured in the vertical carriage 223. Two independently movable worksupporting arms 297 are mounted for horizontal sliding movement on the wall 223 and may be locked in adjusted position by a locking lug 287 operated by a knob 295. Each arm has a free end 229, 300 approximately circular in shape and each bearing a mounting centre with conical points 305, 329 which engage holes in the ends of the shaft 331 on which the gear 333 is mounted. The centre 305 is axially movable to accommodate gear shafts of differing lengths. The rack holding means, Figs. 19 and 24.-A rack pin 457 simulating one tooth of a theoretical rack for meshing with the gear being gauged is mounted for longitudinal movement in a groove in a face plate 423, locking means 459, 465 being provided. The face plate 423 is rotatable on a transverse carriage 397 about an axis parallel to the optical axis and to the axis of the gear supporting centres by a knob 445 and is locked to the carriage by an ear 451 and a screw 453. The carriage 397 is movable transversely by a knob 413 in dovetail guides in a guide plate secured to a longitudinal carriage 361 and may be locked relatively thereto by a locking screw 403. The longitudinal carriage 361 is movable by a pinion on a shaft 349 actuated by a knob 381, the pinion engaging a rack secured to the carriage, the rack lying in a longitudinal guiding recess in a part tubular support 343 secured to the comparator housing by bolts 337 a locking screw being provided. The longitudinal travel of the rack holding means is measured by a scale on the upper part of the support 343 and its transverse movement may be measured by clamping a dial gauge on a bracket 417 so that its plunger co-operates with a flat 420 on the transverse carriage. Setting-up and use.-The apparatus is used with a comparative chart gauge, Fig. 8, containing many sets of rack teeth of different diametral pitches in nested relationship each with its own pitch diameter line and the support means is set up for a particular test by means of an alignment fixture 471, Fig. 31, inserted between the conical centres 305, 329 and having an adjustable pin 481 settable by means of gauge blocks to project a distance equal to the pitch radius above the axis of the centre, the horizontal longitudinal carriage and the vertical carriage being adjusted until the pin 481 lies in the focal plane of the comparator with its tip on the selected pitch diameter line of the chart. The rack tooth pin 457 is then set up so that its image coincides exactly with the chart picture of the tooth to be used in testing as in Figure 7. During testing, by moving the transverse carriage the gear can be made to " roll " on the stationary rack tooth. Specification 674,193, [Group XX], is referred to.