Sankyo Automation

RollerDrive CNC

The RollerDrive CNC is a circular table designed to fulfill the demands of the latest machine tools for increased speed and precision. It uses our zero-backlash reducer known as RollerDrive, which transmits motion without distortions. The RollerDrive CNC remains robust against external forces unlike existing gears and torque motors. The precision and rigor of the zero-backlash technology results in a rotational accuracy of ±10 arc sec. and repeatability of less than ±4 arc sec. The RollerDrive CNC powerfully persists while cutting through hard metals.

Due to its mechanically rigid, zero-backlash structure, the RollerDrive CNC does not require clamp operation. This eliminates clamp and unclamp time while using no energy the way conventional hydraulic systems do. This distortion free performance and no-clamp design delivers ultra fast positioning that leads to higher productivity. For instance, a typical 90 degree rotation can be completed within 0.4 seconds.

The unique mechanism of the RollerDrive allows the RollerDrive CNC to withstand years of operation without compromised performance. This means no internal part wear and no loss of precision. Regular calibration and readjustment is unnecessary when you choose the RollerDrive CNC.

The RollerDrive mechanism mainly consists of an input shaft and output turret with embedded roller followers. A cross-roller bearing works to support the output turret with minimal run out.

Preloaded roller followers contact the input rib surfaces with a wedge-shaped cross section. This can be adjusted my moving the input axis, which in turn eliminates backlash completely – meaning superior precision and rigor for CW and CCW rotation; as displayed in the diagram to the right.

Even with preload and zero-backlash, the needle bearing type roller followers transmit power by rolling rather than sliding. This allows the RollerDrive to achieve an outstanding efficiency of 90% or more. RollerDrive guarantees a lifetime of wear-free durability.

All parts are made from only qualified alloy steels; machined and ground with our ultra-precision machining system.

The RollerDrive product series are widely used in various industries that require the highest excellence in performance levels. Machine tool companies are no exception, being at the forefront of these industries and applying our RollerDrive technologies to the world’s leading machine tools.

The “RollerDrive QUALITY” logo encompasses rotary axis speed, precision, and mechanical stiffness – essential performance qualities for standing up to heavy cutting work. This logo is available to RollerDrive users to make their applications distinctive in their market. Contact Sankyo Automation for details on the use of this logo.

• No backlash
• Rolling contact transfers power while eliminating wear
• High accuracy and excellent efficiency
• Preloadable for high rigidity

RollerDrive

Servo-driven motion control systems play a major role in defining the performance of FA equipment. Machine specifications and performance requirements may be developed with the assumption that the given system is capable of producing the expected motion. However, if the motion control system has preexisting control instabilities such as backlash or is rigidity lacking, the output motion will deviate from the control input. In turn, it is difficult to to achieve an ideal, expected performance.

The RollerDrive® RA Series mechanically reduces the speed of the servomotor while delivering powerful torque, rigidity, and stability. It features a unique preload mechanism that produces zero-backlash – resulting in the output motion responding faithfully to the input control references. Numerous features make the RollerDrive® RA Series a revolutionary motion control unit for FA applications. Consider such qualities as the high efficiency afforded by the rolling transfer of power, wearless design, compact packaging resulting from the right-angle input to output shaft layout, and the convenient, large-diameter hollow output shaft.

When assessing conventional motion equipment, the quality of motion is primarily evaluated by its accuracy and rigidity while static. However, the accuracy and stability impacts FA equipment performance in motion just as much as it does in a standstill condition. Backlash or poor responsiveness can degrade the dynamic accuracy of motion control equipment, preventing it from creating the motions intended by the control references.

The RollerDrive® uses zero-backlash technology to create output motions that are faithful to the input control references; delivering improved performance levels in all kinds of FA equipment.

Settling time is instantaneous for precise positioning while speed variation during motion is minimal for accurate synchronized operation. The RollerDrive® is virtually maintenance free, resulting in a reduced cycle cost of the entire FA system.

The output shaft of the RollerDrive® has very minimal runout, which makes it suitable for precision θ-axis positioners and alignment tables. Its thin, compact design makes it ideal for X-Y stages and other positioning units as well.

Improved speed and reciprocating repeatability allows thin, profile drive layouts for compact integration, while piping and cables can easily be passed through the hollow bore in the large diameter output shaft.

Backlash is eliminated entirely by maintaining constant contact between the wedge-shaped ribs on the input shaft and the roller followers under preload. Preload is adjusted by turning the adjustment mechanism on the input shaft.

The steel alloy input shaft is built to meet extremely tight tolerances using the latest in machining theory and equipment. These shafts are balanced to suppress self-excited vibration under high speed rotation.

Roller bearing construction transfers torque through the rolling action of the roller followers. Rolling contact maintains the initial accuracy, even for extended periods of use.

The output shaft has an oversized hollow bore that allows easy passage of wiring and piping, or the shaft of another device, allowing for design flexibility.

Inside the output unit, cross roller bearings are used for increased rigidity and minimal runout.

The motor shaft is rigidly clamped to the input shaft of the reducer for a direct transfer of power from the motor. The motor base is designed to absorb error in alignment during assembly (patent pending).

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