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Handling module rivals Scara robots but is half the price

20 February, 2011

Festo has developed a compact motion control subsystem for machine-builders that provides programmable rotary and linear movements at a low cost. The EHMB module allows rotary and lifting movements to be controlled independently, for fast and accurate positioning in applications such as parts-handling. The device can perform similar loading and unloading movements to Scara robots, with a comparable performance, but at less than half the price.

The rotary axis is actuated electrically using either a stepper or servo motor, while the lifting axis can be driven by either electric or pneumatic cylinders. Users can tailor the price and performance of the module by choosing to use a motor and an electrical actuator for both axes, or by combining a motor with a lower-cost pneumatic cylinder.

A typical low-cost configuration would pair a stepper-driven rotary axis with a pneumatic cylinder to provide simple, accurate linear movements between two positions. A more demanding application, needing freely programmable linear positioning, could use servomotors and controllers for both axes, with the linear axis being driven by an electric cylinder. This all-electric approach allows complex rotary and linear movements to be implemented, thus improving machine productivity under software control alone.

The EHMB modules are available in two sizes. The smaller version can accommodate payloads of up to 3kg, generate more than 3Nm of torque, and handle moments of inertia up to 30kg•cm2. It is ideal for providing Z movements in portal and Cartesian parts-handling systems.

The larger model is more suitable for stationary uses – such as loading, unloading and stacking applications. It accepts payloads up to 5kg, can generate 8.8Nm of torque, and handles moments of inertia of up to 100 kg•cm2.

Both versions offer a choice of 100mm or 200mm stroke lengths, and can generate up to 480N of lifting force. Depending on the choice of motors and cylinder, both modules can handle linear speeds up to 500mm/s with a repeatability of ±0.1mm, and rotational speeds up to 300 rpm with a repeatability of ±0.05 degrees. For example, a 1kg load can be rotated through 180 degrees in 250ms.

The modules’ hollow lifting shafts can be used to route compressed air tubes and electrical cables to the platen for attachments such as grippers. The linear axis can be mounted on any of the module’s three sides. The rotating and lifting platen is the only part that extends beyond the module, and can be installed either way up.

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