Patent GB-1364379-A (GB)
Title: Apparatus for the fine balancing of grinding wheels
IPC: B24B41/04
Filed: 1972-07-27
Abstract: 1364379 Rotary unbalance measurement and compensation SCHAUDT MASCHINENBAU GmbH 27 July 1972 [29 July 1971] 35072/72 Heading G1N [Also in Division B3] Apparatus for balancing a grinding wheel 13, Fig.2, comprises two balance masses 25, 27 adjustable jointly in one direction about the axis of the wheel and arranged one on each side of a third balance mass 26, the masses being arranged in a housing 14 and on a common balance shaft 22 rotatable relative to both the housing and grinding wheel, and a pinion 30 mounted in the housing and meshing with a bevel gear 31 on the third balance mass 26 and a bevel gear 29 on one 25 of the other masses, the gear 29 and mass 25 being rotationally fixed to the shaft and the gear 31 and mass 26 being rotatably mounted on the shaft. The balance masses and housing 14 are located within the end of the spindle 12 supporting the grinding wheel, the spindle at its other end having a pulley engaged by V-belts 11 and a device for controlling the position of the masses. The housing 14 is rotatably mounted in bearings 15, 16 in the spindle and connected to a hollow shaft 21. As described, fourth and fifth semi-circular balance masses 18, 19 are secured to the housing one on each side of the third mass which is secured to the bevel gear 31 rotatable on balance shaft 22 which extends through the hollow shaft 21. The pinion 30 is mounted in the mass 19 and engages the bevel gear 31 and the bevel gear 29 which is secured to the mass 25 and is keyed to shaft 22 as also is mass 27. Rotation of the shafts 21, 22 together angularly adjusts the balance masses in unison. The hollow shaft 21 is connected by a coupling 32, Fig.1, to the spindle 12 and by a coupling 33 to the shaft 22 which, in turn, is connected to an electric motor 34, the couplings being electromagnetic. Normally the couplings are engaged. When coupling 32 is released, rotation of motor 34 rotates shafts 21, 22 relative to the spindle 12 for rotation of all the masses. When coupling 33 is released, rotation of motor 34 rotates shaft 22 relative to shaft 21 and spindle 12 to rotate the masses 25, 26, 27. A vibration transducer 38, Fig.7, and reference generator 39 are mounted on the spindle assembly and connected to a circuit controlling the couplings 32, 33 and motor 34. Signals from the transducer reference generator are supplied to phase-sensitive detector 40 which produces a signal which is a measure of the unbalance and is fed to a comparison stage 42. If the value of the signal is greater than a nominal value, the signal 1 passes to an 'AND' gate 43. The signal from the gate 43 passes to an 'OR' gate 44 to set a flip-flop 45 and releases coupling 32. A flipflop 46 is also set to prepare an 'AND' gate 47 and, by a dynamic OR gate 48 a flip-flop 49 to actuate delay members 50, 51. The AND gate 47 passes a signal 1 to OR gate 52 to operate the motor 34. If the signal from detector 40 deminishes, a differentiation state 53 supplies negative voltage to a zero discriminator 54. An AND gate 55 connected to the discriminator supplies two AND gates 56, 57 and the delay members 50, 51 remain without effect. A signal from the gate 55 through an OR gate 59 sets a flip-flop 60 to prepare an AND gate 61. When motor 34 has run to adjust all the masses to reduce the vibration to a minimum, the stage 53 gives a signal 0 to discriminator 54 whereby AND gate 55 produces a signal. Flip-flop 49 is thus cancelled and flipflop 63 set to engage coupling 32 and release coupling 33. A signal at gate 61 strikes delay member 64 which when it runs out cancels flipflop 60 and sets flip-flop 65 to prepare AND gate 66 so that after the delay of member 64 the motor 34 is again switched on and the masses 25, 26, 27 adjust until the out of balance is a minimum. In another embodiment, the spindle 12, shaft 21 and shaft 22 are connected by gearing to couplings arranged to be driven by a motor for controlling the position of the balance masses. In a further embodiment, the balance masses are arranged to be adjusted manually.