Torque motor without interference forces and interference torques in the µm range

Details: Released: 14.11.2017; Last updated: 09.03.2022; Hits: 5303

With an optimization of Torque motor SRV series from Idam Schaeffler eliminates disturbance forces and disturbance torques of the drives, which with the usual design in Rotary axes and Rotary tables Cause tilting of the axis or the clamping surface in the micrometer range. This tilting of the motors affects the surface quality during precision machining and leads to additional costs due to the necessary rework.

Within the Machining With very stiff and directly driven rotary axes in ultra-precise tool machines, the phenomenon of short-wave surface defects can occur on workpieces. They are often in need of optical effects Surfaces as recognizable by regular stripes or shadows or by grinding stars on the front sides. These accuracy deviations from less than one to a few micrometers lead to quality problems on high-precision workpieces in mold making, lens finishing or at Gear parts highest quality.

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The cause of the deviations are pulsating axial and radial forces from the Magnetic fields of the torque motor, which act as disruptive forces and torques on the Storage impact. These relatively small loads for the bearing cause axial displacements and tilting in the submicrometer range, which can be reflected in the workpiece surface. In the case of grinding stars in particular, the error period is usually due to the number of poles.

Double structure in the torque motor

The phenomenon is by no means new, but they are Surface qualities so high today that it can be seen in the machining marks. In addition, the requirements for shape tolerances and surface quality in some industries have increased so much that the effort for reworking is no longer tolerated and the market is demanding a solution. As a solution, the engineers at the specialist for direct drives developed a "double" Engines Structure in which the disturbing forces and torques occurring in the torque motor balance each other internally and so the so-called surface defects can be effectively avoided in ultra-precision manufacturing.

The importance of precision sensors for engine feedback

Those based on this principle SRV Despite their more complex structure, torque motors are interchangeable with the torque motors available on the market. Air gap diameters from 89 to over 460 mm and magnet heights from 25 to 200 mm are planned for the new series. The motor series has already started with an air gap diameter of 89 mm.

By using the new SRV torque motors, there is no measurable input of pulsating, motor-related axial and radial forces into the machine structure. The best surfaces without optical defects and with extreme form and dimensional accuracy can now be achieved. At the same time, the new motors offer very high speeds of up to 14.000 min^-1.