PI U-651 Ultra-Low Profile Rotation Stage with Ultrasonic Motor

PI's ultra-low profile ultrasonic linear-motor-driven U-651 series of rotary stageswas designed for high-speed, high-stability positioning tasks with limited space. These stages are the lowest profile closed-loop linear motor equipped micropositioning systems in the industry. Based on PI’s proprietary PILine® ultrasonic ceramic motor technology (US Pat. No. 6,765,335) these stages provide velocity to 720 deg/sec, with very rapid start/stop behavior while holding a stable position with zero energy consumption when at rest.

PILine® stages are particularly suitable for applications that require fast precision positioning. When switched off, the self-locking drive holds the position of the stage mechanically stable. Energy consumption and heat generation is therefore considerably reduced. Applications with a low duty cycle that are battery-powered or heat-sensitive benefit from these characteristics. The position of the axis is measured by an encoder and an optical reference switch allows reliable repeatable motion. The piezomotor drive principle and its electrical operation is inexpensive and can be customized.
PILine® ultrasonic piezomotors

An integral part of a PILine® ultrasonic piezomotor is a piezo actuator that is preloaded against a movable, guided runner via a coupling element. The piezoceramic actuator is excited to ultrasonic oscillation by a high-frequency AC voltage between 100 and 200 kHz. Deformation of the actuator leads to periodic diagonal motion of the coupling element relative to the runner. The feed created is a few nanometers per cycle; the high frequencies lead to the high velocities. Preloading the piezoceramic actuator against the runner ensures self-locking of the drive when at rest and switched off.
Direct position measurement with incremental encoder

Noncontact optical encoders measure the actual position directly at the motion platform with the greatest accuracy so that nonlinearity, mechanical play or elastic deformation have no influence on position measuring.

Crossed Roller Bearings

With crossed roller bearings, the point contact of the balls in ball bearings is replaced by a line contact of the hardened rollers. Consequently, they are considerably stiffer and need less preload, which reduces friction and allows smoother running. Crossed roller bearings are also distinguished by high guiding accuracy and load capacity. Forced guiding of the rolling body cages prevents the roller bearings from creeping.

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