Robots usually always perform the same tasks, which they repeat with high precision - making them ideal for mass production. However, flexibility is increasingly required to produce small batch sizes. Equipped with innovative tool changers that can be operated pneumatically, electrically or manually, robots are becoming flexible all-rounders with which users can also produce small batches or individual pieces economically. Brushless DC flat motors with high power density are the driving force behind the electrically operated changer systems.

With the TKX series tool changing systems, IPR from Eppingen aims to open up new possibilities for robotic automation. For this purpose, an adapter is attached to the end of the robot arm, which picks up various tools from a magazine. The same robot can, for example, first grip and position a workpiece, then process it and finally check and document the quality using a contour probe or a camera. The adapter is equipped with feed-throughs for corresponding tool functions and lateral screw-on surfaces for additional modules. The main function of the adapter is the fast and reliable locking of the tool train after picking up and unlocking after tool placement.

Various drive solutions

Traditionally, this task is performed pneumatically. Compressed air technology has proven itself over decades and is suitable for handling heavy objects. However, a pneumatic system requires compressors, lines and its own control system, which means a high investment for new installations. Pneumatics is often not possible in industries with increased requirements for cleanliness and hygiene, such as microelectronics or food, due to the risk of contamination from escaping compressed air; in cleanrooms, for example, it is taboo. Electric drives are therefore increasingly being chosen.

Roman Batz, development engineer at IPR, explains: "In addition to the hygienic safety, it is above all the flexibility in use that speaks in favor of electric motors. In contrast to a compressed air connection, a socket can be found practically anywhere. New industrial plants today often do not require a pneumatic system. For cobots and smaller robots as well as for decentralized locations, the electric version is almost always the better solution anyway." There has been progress in motor technology in recent years; many applications require a lot of power with small dimensions. "At Faulhaber, we find motors that can easily keep up with pneumatic drives," adds Roman Batz.

High performance required

The small motors have to be able to do a lot: the currently most powerful electric tool changer, the TKE 300, is suitable for handling objects weighing up to 300 kilograms. It is used in metal processing, for example, when robots handle cast ingots or large forged parts. In this case, the entire mass with its tensile force acts on the locking ring in the changer. The torque supplied by the motor in stationary mode would actually be sufficient for secure holding. However, IPR has installed additional kinematics developed in-house to ensure reliable and backlash-free locking.

The drive power for opening, closing and holding is provided by a brushless motor from the Faulhaber BXT family. The motors were developed on the basis of the classic external rotor design. Thanks to innovative winding technology and an optimized design, the brushless DC servomotors deliver torques of up to 134 milli-Newton meters with a diameter of 22, 32 or 42 millimeters and deliver a continuous output of up to 100 watts with high efficiency. The compact motors therefore exceed the usual standards in this drive class. The ratio of torque to installation space and weight is particularly impressive. Thanks to the high copper fill factor and the design of the pole pieces, the magnetic field is strong and the cogging torque is low.

Changer portfolio with all drive types

This power density is one of the prerequisites for the unique selling point of IPR's new product family, which Roman Batz describes as follows: "The TKX series is the first tool changer on the market that is available with both pneumatic and electric drives on the same platform. A manual version is also part of the product family. This means that the entire range of accessories can be used with all drive types. Switching to electric operation does not require any major effort either." The electric tool changers will be available in seven sizes for handling workpieces from 3 to 300 kilograms.