GB251746A - An improved method of and apparatus for testing the dynamic balance of rotary bodies - Google Patents

Abstract

251,746. Avery, Ltd., W. & T., and Linley, C. M. March 30, 1925. Testing balance of rotary apparatus. - The apparatus comprises a bed mounted on resilient supports, a pair of hollow mandrels carried by the bed and adapted for connection to the body to be tested, a pair of shafts slidably secured within the mandrels, eccentrically displaceable weights in conjunction with the shafts and provided with means for varying the eccentricity, and means for effecting rotation of the body. The trough-shaped body 6 is mounted on springs 7. Adapted to slide on guidings 6<a> on the bed 6 are two pairs of bearing members 9 which may be clamped to the guideways in any adjusted position. Each member 9 has a central aperture in which is disposed a ball race 11, each pair of ball races affording bearings for a mandrel 12 formed at the inner end with a. disc-like section 12a having a V-notch 12b adapted to receive a driving belt. Secured to the disc 12<a> and spaced therefrom by distance-piece is a disc 14 between which and the disc 12<a> is guided a displaceable weight 15. Intermediate the members 9 the mandrel is formed on the outer surface with a helical groove. Within the mandrel is a shaft 16 which may slide axially without rotating relatively to the mandrel. The outer end of the shaft 16 is provided with a ball thrust bearing 19 within a collar 21, an extension 21<a> of which is screwed into a cross-piece 23 integral with a frame 9. Concentrically arranged about each mandrel are a pair of annular members 27 adapted to be slid lengthwise of the apparatus by a forked lever 28 pivoted by a link 29 to the member 9. Rotatably mounted between the members 27 is an annular block 27b having diametricallyopposite pins 30 to the lower ends of which are secured guide-pieces 31 working in longitudinal grooves 16<a> in the shaft 16. Bushes 32 disposed about the pins 30 work in the helical grooves 12<c> in the mandrel 12. The crank shaft or rotor to be tested is connected at each end to the discs 14 and the mandrels rotated. The lever 28 and the handles 24<a> are operated until there is no vibration of the bed. The handles 24<a> effect displacement of the weights by moving the shaft 16 longitudinally, this movement causing projections 15b on the weight 15 to slide along grooves 16c in the inner end of the shaft 16 and the weight to move along a diameter of the plane of rotation. Simultaneously movement of the levers 28 effects a rotation of the mandrels 12 and alters the angular relation between the diameter containing the sliding weight and the body under test. The movement of the shaft 16 can be read off on a scale 25 and the movement of the lever 28 is also read off on a scale not shown. By suitable calibration of these scales the amount and position of the unbalanced mass in the test body can be determined.