LORD designs balancing systems for high-speed, high-precision grinders. The response of the system enables balancing corrections to be performed in seconds, and can be used on machines with automatic wheel changes.
The balancing system is comprised of five parts: balancer, actuator coil, sensors, controller and software. The balancer is mounted permanently onto the spindle of wheel hub; sensors continuously monitor the vibration levels while running. When an increase in vibration is detected above a pre-determined level, the controller sends an advisory message to the operator and the machine PLC, either of which can instruct the balancer to make an automatic balance correction.
The Balancers have been designed to address the following:
- Grinding wheel wear
- Chatter caused by vibration
- High-speed spindles
- Precision two – plane balancing
- Machine Tool PLC interface
- Reduced cycle times
- Improved surface finish and dimensional accuracy
- Extended wheel and spindle bearing life
The Balancer
The electro-mechanical balancer contains a balance ring, which mounts directly onto the spindle shaft or wheel hub. Inside the balance ring are two symmetrical counterweighted rotor assemblies which, when directed, move to create a net correction vector that will offset the measured unbalance. The counterweighted rotors are held in place using permanent magnets that are fixed to the rotors. These magnets create a holding torque, which prevents the rotors from slipping during normal operation, ramp-up or coast down. When a balance correction is required, actuator coil power pulses are sent to magnetically step the rotors to the desired position in a few seconds.
Balancing System Features
- Balances at spindle speeds up to 40,000 RPM
- Balances to levels below G-1.0 at speed prior to grinding or truing
- Balances the entire spindle assembly in seconds after each wheel change
- Protects spindles by monitoring vibration continuously and shutting down automatically if vibration is excessive
- Rugged construction withstands the harshest environment
The Actuator Coil
The actuator coil typically mounts to the wheel guard door. With no moving parts, the actuator coil pulses power to the balancer assembly. The counterweighted rotors are thus moved to the desired counter-balance position. The actuator coils contains sensors for monitoring spindle RPM as well as the angular location of each counterweighted rotor.
The Controller
The controller continuously monitors vibration levels. When a change occurs which exceed a preset level, the controller determines the optimum balance correction required. Depending upon the mode of operation selected the controller will send an advisory message to the operator and the machines PLC (via either PLC I/O or an RS232 serial port) either of which can instruct the balancer to make an automatic balance correction.
The Software
The full-featured graphical user interface software provides the ability to view real-time amplitude and phase information in both numerical and graphical format. Additionally the software provides the ability to view the balancer correction vector, which provides valuable information regarding the available correction capacity.
The ability to remotely access the software via Ethernet and configure the balancer while initiating the balance correction is a popular feature of the software package.