All-in-one rotary/lifting module offers robot-style handling and positioning performance at a fraction of the cost

Assembly Automation

ISSN: 0144-5154

Article publication date: 27 September 2011



(2011), "All-in-one rotary/lifting module offers robot-style handling and positioning performance at a fraction of the cost", Assembly Automation, Vol. 31 No. 4.



Emerald Group Publishing Limited

Copyright © 2011, Emerald Group Publishing Limited

All-in-one rotary/lifting module offers robot-style handling and positioning performance at a fraction of the cost

Article Type: Mini features From: Assembly Automation, Volume 31, Issue 4

Festo has launched a compact integrated motion control subsystem for automation applications that provides machine builders with a highly flexible means of providing programmable rotary and linear movement. Ideal for parts handling and positioning applications, the new EHMB module features a unique decoupled design, enabling the rotary and lifting movements to be controlled completely independently, for exceptionally fast and accurate positioning.

The subsystem is capable of performing similar types of loading and unloading movements as many industrial SCARA robots, 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 a motor and electrical 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.

Festo offers a choice of two EHMB modules, to simplify application matching. The smaller size 20 model can accommodate payloads of up to 3 kg, generate more than 3 Nm of torque and handle moments of inertia as high as 30 kg/cm/cm. It is ideal 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 5 kg, it can generate 8.8 Nm of torque and handle moments of inertia of up to 100 kg/cm/cm. Both modules offer a choice of 100 and 200 mm stroke lengths, and are capable of generating up to 480 N 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 500 mm/s with ±0.1 mm repeatability, and rotational speeds of up to 300 rpm with a repeatability of ±0.05° – a 1-kg load, for example, can be rotated through 180° in 250 ms.

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

Several factors make the EHMB particularly easy to install. The lifting shaft is hollow – the size 20 module has an internal shaft diameter of 14 mm, while that of the larger module is 21 mm – which provides ample space for routing compressed air tubes and electrical cables up 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.

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