Handling module provides independent linear and rotary motion

According to Festo, module is capable of performing similar types of loading and unloading movements as many industrial SCARA robots, and with comparable performance, but at less than half the cost.

Users may also tailor the price/performance of the motion subsystem by choosing to use an electric motor and electric actuator for the two axes, or a motor and pneumatic cylinder. Festo's modular EHMB design can be configured with a range of the company's positioning cylinders, motors and controllers.

The rotary axis is always actuated electrically using a stepper or servo motor, whereas the lifting axis can employ a Festo DNCE electric or DNC pneumatic cylinder, depending on the user's performance requirements and technology preferences. A typical low-cost configuration would comprise a stepper-driven rotary axis and a standard DNC pneumatic cylinder to provide simple high-accuracy linear movement between two positions. A more demanding application, requiring freely programmable linear positioning, could use suitable Festo servo motors and controllers for both axes - the linear axis being driven by a DNCE electric cylinder. This all-electric approach facilitates implementation of complex rotary/linear movement, with the significant advantage that machine productivity improvement, and even retooling, can be accomplished under software control alone.

Two sizes

Festo offers a choice of two EHMB modules to simplify application matching. The smaller size 20 model can accommodate payloads of up to 3kg, generate more than 3Nm of torque and handle moments of inertia as high as 30kg/cm/cm. It is suitable for providing the integral Z movement in portal and Cartesian parts handling systems. The larger size 25 model is more suited to stationary use, such as in loading, unloading and stacking applications. Capable of accommodating payloads as high as 5kg, it can generate 8.8Nm of torque and handle moments of inertia of up to 100kg/cm/cm. Both modules offer a choice of 100mm and 200mm stroke lengths, and are capable of generating up to 480N of lifting force.

Festo's EHMB modules offer exceptionally fast and accurate lifting and rotating capabilities. Depending on the choice of motors and cylinder, both models can handle linear speeds as high as 500mm/s with +/-0.1mm repeatability, and rotational speeds of up to 300rpm with a repeatability of +/-0.05 degrees; a 1kg load, for example, can be rotated through 180 degrees in 250ms.

Mechanically, Festo's new rotary/lifting unit is similar to a Festo ERMB rotary actuator, but with the platen attached to a guided splined shaft that is free to move through the actuator's body under control of an adjacent linear axis. The cylinder's piston rod end is directly attached to the platen support bearing by a ball-and-socket coupling.

Easy integration

Festo says that several factors make the EHMB particularly easy to install. The lifting shaft is hollow - the size 20 module has an internal shaft diameter of 14mm, while that of the larger module is 21mm - which provides ample space for routing compressed air tubes and electrical cables to the platen for controlling attachments such as gripper units; all mounting interfaces are compatible with Festo's existing range of pneumatic grippers. Furthermore, the linear axis can be mounted on any of three sides of the EHMB module to suit the layout of the customer's machine. Overall, the EHMB has a very compact work envelope - the rotating/lifting platen is the only part that extends beyond the confines of the module - and can be installed either way up to suit the application.

Festo produces several accessories for the EHMB module. These include an adjustable end-stop for the lifting shaft, for use with pneumatic cylinders, a support bush for flexible tubes and cables, and a shaft cover kit. An axial motor mounting kit is also available for modules that employ an electrical linear axis.