Rockwell Automation 8510 AC Spindle Drive System User Manual - Manual (Page 8)

Introduction
Chapter 1
1-4
Servo Mode – configures the drive to be used as a velocity servo in a
closed position loop system. Whenever the CNC is operating the spindle
drive in a closed position loop, such as during spindle orient or when
performing C-axis machining on a turning center, this operating mode
should be used. In servo mode, only analog speed commands can be used,
the acceleration rate ramp generators are disabled, and a maximum
integrator gain clamp is added to guard against limit cycle conditions in
high friction applications. The analog input scaling can be set for a
different maximum speed in servo mode than is used in spindle mode. An
optional high speed, high linearity A/D converter can be added for
contouring and high bandwidth applications. The 8510 has ample dynamic
performance to allow using it as a high power axis servo.
Torque Mode – configures the drive to function as a torque controlled drive
rather than a speed controlled drive. When this mode is active, the analog
input is commanding a level of motor torque rather that a specific motor
speed. The connected load or an external control loop must provide the
speed control or the motor will be accelerated to maximum speed and the
drive will shut down on an overspeed condition. A single digital input can
instantaneously switch the drive between torque control and speed control
modes. Torque mode allows the drive to operate as the torque follower in
leader/follower or anti-backlash dual drive configuration. Some motion
control systems close both the position and velocity loops from a single
feedback device and output torque commands to the drive amplifier. In
torque mode, the 8510 can be used with these motion control systems.
Optimized Performance For Multi-Speed Gear Boxes
Many multi-speed spindle gear boxes provide very different drive loading
or have different performance requirements in each gear range. Some
directly driven spindles may have large differences in load inertia or
performance requirements in certain situations. To provide optimum
performance in each of these different situations, the 8510 drive can store
totally independent sets of all drive configuration and tuning parameters for
up to four different gear ranges or sets of operating conditions. Two binary
coded digital inputs allow the CNC or other control system to select the
appropriate parameter set while the drive is running. Changeover takes
only about 30 milliseconds.
Since all configuration parameters can be changed for each data set, this
feature could be used to select multiple preset orient positions, change the
maximum speed at maximum command scaling, or change any of the
preset speed or load detectors in addition to optimizing the dynamic
response of the drive. This flexibility can help eliminate the need for
making performance compromises in different operating conditions.