GB299636A - An improved method of and apparatus for testing the balance of rotatable bodies - Google Patents

Abstract

299,636. Lundgren, J. Dec. 20, 1927. Testing balance of rotary apparatus. - Comprises a method which consists in supporting the body to be tested, rotating the body, limiting in one direction the movement of the body under the unbalanced forces and permitting the body to move freely in the opposite direction so as to influence an electrical angle indicating device whereby the angular position of the unbalance can be observed. A foundation plate 1 provided with a raised portion 2 carrying a motor 3 is slotted to receive the securing bolts of base plates 7 of the specimen supports which are longitudinally adjustable on the plate 1. Each base plate is provided with an upwardly extending portion 9 to which is connected a bracket 10 bifurcated to receive a spring holder 12 pivoted to it. The holder has secured to it a spring 15 carrying a V-bearing 17. Each holder is threaded to receive a screw 20 provided with an enlarged and graduated collar 21 and a knurled handle 23. A contact carrying plate 25 is also fixed to the part 9 of the base to the upper end of which is secured a bar of insulating material 26 carrying a contact screw 30 adapted to co-operate with a contact 31 secured to the bearing. Each base plate 7 has one or more studs 34 connected at the upper end to a cross bar 35 provided with an adjustable screw stop 36. The motor 3 drives the specimen through a universal coupling 38, flexible rod 39 and coupling 40. The dial hand 51 is driven from the motor shaft through gears 41, shaft 43 and gears 46, 47 and moves over a dial 53 of conducting material. The rotor to be balanced is mounted in the bearings 17 and coupled to the motor. The masses 20 are adjusted to their neutral positions and the motor started. The vibration due to unbalance causes one or both contacts 31 to engage contacts 30 so that on pressing one or both of two pushes the current through an induction coil is broken and a spark passes between the hand and the dial showing the angle of unbalance. The angle is determined for one axial plane of balance by moving the screw 36 to prevent oscillation at the other end, and the mass 20 is adjusted until no spark passes. This gives the amount of unbalance. The same operation is now done for the second balancing plane. Any number of balancing planes may be chosen.