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SPS IPC Drives 2014

Certified safety gripping system

The EGN and EZN gripper modules from Schunk (Germany) provide the functions SLS, SOS, and STO, and are certified according to DIN EN ISO 13849. They thus enable a safe human-machine interaction in confined spaces.

The certified safety gripping system ensures safety with SLS, SOS, and STO up to the level of the actuators (Photo: Schunk)

AT THE SPS IPC DRIVES THE COMPANY PRESENTED its gripping systems. Combined with the ECM Schunk controller, and a safety module, the ready-to-install safety gripping systems comply with performance Level d, SIL 3, and establish personal safety up to the level of the actuators.

By combining the safety gripping systems with safety mats, door switches, light curtains or 3D cameras for room surveillance, for the first time ever it is possible, to define graded protection zones without having to interrupt the production process by emergency shutdown due to close human-machine contact. Instead, the grippers slow down to a save limited speed or safely stop – according to the activated protection zone. The safety gripper is energized during the safe stop, and gripped parts are held even without a mechanic gripping force maintenance. As soon as the protection zone is released again, the gripper switches back into the regular operation mode without any delay, and without having to start up the plant again, thus allowing new scenarios of human-machine cooperation. The DGUV (German Statutory Accident Insurance Association) certified the safety gripping systems with the functionalities SLS, SOS, and STO up to the level of the actuators.

Range of applications

The program of the EGN/EZN 2-finger parallel, or 3-finger centric grippers is based on a modular design and covers a range of applications. Gripping force, speed, and finger position can be flexibly regulated and controlled during the handling process. The gripper fingers are already prepositioned during the process, and therefore short cycle times can be realized. Every module is equipped with the multi-tooth guidance by Schunk: several, parallel prism guides minimize wear and reduce the guiding tolerance. Depending on the size, the mechatronic modules produce gripping forces up to 1000 N.

The certified safety gripping system ensures safety with SLS, SOS, and STO up to the level of the actuators (Photo: Schunk)

Safety functionality can be retrofitted

Beside the basic version, a mechatronic universal gripper is available, which can be also used for dusty, humid or corrosive environments. Depending on the application, trailing or robot-compatible cable sets of various lengths are available. A brushless servo motor is used as a drive, and its rotary movement is converted via a spindle nut into a lifting movement.

A resolver is connected to the motor, and monitors the position of the servo motor, thus allowing positioning of the gripper fingers. The control of the EGN/EZN is done via an ECM controller with plug-in technology, optionally via a CAN network or Profibus. Parameterization is done via PC, USB stick, or rotary encoding switch. In order to benefit from the certified functionalities SLS, SOS, and STO, the grippers and the controller are complemented by a safety module, which monitors the resolver, and compares the values to those of the ECM, without having to modify the gripper.

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