Patent GB-1463512-A (GB)
Title: Methods and apparatus for balancing a rotary body
IPC: G01M1/24
Filed: 1974-08-12
Abstract: 1463512 Automatic control HOFMANN GmbH Gebr [trading as HOFMANN KG MASCHINENFABRIK Gebr] 12 Aug 1974 [23 Aug 1973] 35447/74 Heading G3N Unbalance in a rotary body is removed by calculating unbalance in components relatively dis-  placed at 120 degrees and, after adjustment for the amounts to be removed from each component in respect of the maximum amount allowable in that component, removing the residual amount of unbalance in a direction bisecting the angle between the components, or at 60 degrees to the components. The sequence measurement and control system is responsive to two unbalance conditions (a) that of Fig. 2 (not shown), in which the value of one of the 120 degrees resolved components of the unbalance vector is greater than the maximum allowable, when amounts equal to the maximum allowable of the one component is removed and from the other component an amount equal to the component value less the residual amount in the one component; the resolute, of the remaining equal residual amounts is then removed in a direction at 60 degrees to both components, and (b) that of Fig. 3 (not shown), wherein the residual amount in the one component exceeds the component value in the other component, then the component values are removed in each component direction, and the residual amount in the one direction is removed in the direction of the angle bisector of the two components and the negative residual value in the other component, ignored if within tolerance or removed in a subsequent operation. The sequence control system, Fig. 4, whereby the balancing operation is effected, comprises a component calculator 1 in which X, Y co-ordinate D.C. voltages are converted to negative voltage 120 degrees components at terminals A, B. In the figure all resistors are of equal value and the operation amplifiers invert. A potentiometer 48 sets in the maximum machining amount, equal for both components, and by the use of diode-coupling a negative voltage occurs at terminal 46 or 47, from amplifier 18, 19 when the voltage at terminal A or B exceeds the set voltage from the potentiometer. The voltages at terminals 46, 47 together with positive voltages, corresponding to A or B from amplifiers 8, 9, are fed to amplifiers 26, 27 to derive, by diodes, 34, 35 voltages corresponding to A, B provided they are of less value than the set voltage. At the same time the voltages at terminals 46, 47 are inverted by amplifiers 44, 43 crossconnected to the inputs of amplifiers 8, 9 so that from the inverted output is subtracted an amount by which the voltage B or A exceeds the set voltage causing a corresponding alteration to the voltage at terminals 38, 39. For the unbalance condition b the voltage at terminal 46, or 47 can exceed the voltage at terminal B or A so that the output of amplifiers 8, 9 is negative. This voltage causes a diode 31, 30 to conduct and an output appear at terminal 37, 36 while the out-puts at terminal 38, 39 fall to zero. The voltages at terminals 38, 39 represent the amount of machining to be carried out along the component directions. The voltage at terminal 46 or 47 represents the machining at the bisector or at 60 degrees to each component. A signal on terminal 36, 37 represents a residual amount for condition (b) to be removed by an operation at 180 degrees to the respective component.