How to integrate a direct drive into your machine: Installation options for torque motors

Susanne Reinhard, Baumüller Nürnberg GmbH

Read min.

Because there are no gears, direct drives , offer numerous advantages over traditional motor-transmission combinations, such as greater compactness, high energy efficiency and low service costs.

Installation options for torque motors

Because there are no gears, direct drives offer numerous advantages over traditional motor-transmission combinations, such as greater compactness, high energy efficiency and low service costs. An optimal integration of the electric motor into the machine is the basis for realizing these advantages. For that reason, a variety of installation options are available for the DST2 torque motors from Baumüller.

Torque motors

You can find information on our torque motors here.

The classic solution: Hollow shaft

Torque motors with hollow shaft allow good transmission of power to the machine shaft and excel with their high torsional stiffness
The version with hollow shaft is the classic form of the torque motor. It offers high stiffness and thus enables good transmission of power. The connection to the machine with hollow shaft motors can be made using e.g. a clamping set, a shrink disc, a hydraulic clamping bush or a ball screw.

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Hollow shaft with…

…clamp set

The clamping set is an interference-fit shaft-hub connection that is mounted inside the hollow shaft. This connection is cost-efficient, free of play and has excellent running properties.

…shrink disc

Shrink discs are external clamping devices. Here, torques can be directly transmitted by friction from the hollow shaft to the shaft. In one version, the shrink discs are also available with a flange ring which allows the clamping element to be directly mounted to the motor flange. Because the clamping here is external and the compressive forces only go towards the inside, there are no impermissible clamping forces on the hollow shaft inside the motor. The shrink disc is also free of play and offers excellent running properties, although it does result in an extended structural length.

…hydraulic clamping bush

The hydraulic clamping bushes generate an even surface pressing between the shaft and hub through the tightening of a screw. The advantage here is primarily a quick assembly and good running properties, even if the cost is higher than for the other versions.

…ball screw nut

The ball screw with driven nut is used when it is necessary to convert a rotating movement into a linear movement, in which case the screws can be moved axially through the hollow shaft motor. This allows a high level of positioning precision with high traversing speeds and a high torque. The important thing when connecting hollow motors is that the machine construction absorbs the axial forces produced. No axial forces should act on the motors.

All of the hollow shaft connections are suitable for very high torques. They can meet virtually any requirements, from high positioning precision to rapid assembly to compactness, according to priority. The assembly elements named are not part of the supply scope of Baumüller motors, but we will be happy to refer you to a supplier that we trust.

Reference video

In the video you will learn more about the cooperation with WEIMA Maschinenbau GmbH and get to know our drive solution for shredding systems:

With the ball screw with driven nut, rotating movements can be converted into linear movements.

The flexible solution: Kit motor

With a torque motor as a kit motor you are particularly flexible for integration.

The kit motor consists exclusively of the active parts of the motor, i.e. the rotor and the stator without the housing and bearing. This allows an especially flexible integration with the machine.

The kit motor is delivered without end shields, bearings and encoder mounts and is thus the most flexible version

The industry-specific solution: Thrust-bearing motor

The version with thrust bearing is an industry-specific version of the torque motors specially designed for the plastics industry. Thrust-bearing motors were specially designed for use in extruders. The extruder screw is directly coupled here with the blind hole of the motor, thereby exposing the motor to high axial forces. These forces are absorbed by the integrated spherical roller bearings, which protects the motor from damage.

Torque motors are also available with solid shaft (left) or as a customized option also with blind hole shaft (right)

Reference video

In an interview with our customer Bemaco Engineering, you can find out more about a Coex system that has been equipped with our drive technology:

Solid shaft and blind hole shaft

The DST2 torque motors are additionally available with solid shaft or also with blind hole shaft. Although the solid shaft reduces the stiffness in the drive train, it simplifies assembly, is compact, has positive damping properties and can e.g. have a balancing effect with offset or production tolerances. Advantages of blind hold shafts are that the machine spindles can reach into the motor and a coaxial sensor mount and thus the use of a safety sensor is possible.

In the motor version with blind hole shaft, the machine spindles can extend into the motor.

Torque motors DST2

You can download our brochure with detailed information on our torque motors here:

The diversity of assembly options simplifies the change from high-loss hydraulic solutions and classic motor-transmission combinations to direct drives. Contact us for further information on the integration options with our high torque motors.

Do you have anymore questions?

Markus Keila
Product Manager Motors

Our responsible expert will be happy to assist you.

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