Integrated Safeguarding of a Robot System with Wireless Safety

Staehle GmbH in Schifferstadt has been manufacturing aerosol cans since 1956. A wide variety of customers from numerous industries trust in the quality of Staehle. For a fast and safe pallet change, the design engineers from SSP Safety System Products, together with Staehle, developed a clever airlock function that is operated with the help of the robot and evaluated by the "Safety Simplifier" safety controller with a wireless interface. In addition to this airlock function, SSP supplied a comprehensive safety package consisting of a safety fence, safety switches, a safety controller, and a risk assessment.

Challenge: Safe and Fast Pallet Changing

The Staehle company in Schifferstadt produces aerosol cans for various customers in a wide range of industries and is one of the leading manufacturers in Europe. "Surely everyone of us has already held a can in their hands that comes from the plant in Schifferstadt," says Mr. Sauter, Head of the Electrical Workshop. The goal was to find a safety concept for a safe and fast pallet change.

Solution: Customized Safety Concept and Design

To enable a fast and simultaneously safe pallet change, the design engineers from SSP Safety System Products, together with Staehle, implemented an innovative airlock solution. This is operated by the robot and monitored by the Safety Simplifier safety controller via a wireless connection. In addition to the airlock function, SSP provided a comprehensive safety concept that includes a safety fence, safety switches, control technology, and the complete risk assessment.

Figure 1: Robot system for packaging aerosol can bottoms

Staehle relies on an integrated safety concept from SSP Safety System Products, which utilizes, among other things, the "Safety Simplifier" safety controller
with a wireless interface. This allows safety functions to be linked more easily and reduces wiring and cabling effort to
a minimum.

Another special feature of this application is the created airlock function: The robot moves a hood over the pallet to be changed, so that the packaging process in the cell can safely continue. A cylinder locks the hood in place, and the SAFIX safety sensor ensures safe position monitoring. The application initially begins with the production of cones, the lids of the aerosol cans. The cones are punched from sheet metal, shaped in several presses, and finally receive a rubber seal. The robot then picks up a string of 200 parts and places them into insertion pallets.

At the end of the packaging process, the fully loaded pallets must be replaced. In order to carry out the pallet change without stopping the machine, an airlock was developed together with SSP. Four pallets can be loaded per robot. When a pallet change is due for a specific pallet, the robot moves a hood over the pallet to be removed. In this way, an additional drive for moving the hood could be saved. Once the hood is over the pallet, it is locked and the SAFIX RFID safety sensor ensures safe position verification. The airlock is now locked, and the safety guard lockings on the door are released.

Figure 2: Safeguarded airlock for pallet changing

The loaded pallet can be removed and replaced with an empty one. Meanwhile, the robot continues to work undisturbed and loads one of the remaining three pallets. The safety guard lockings from the "tGard" series also come from SSP's portfolio. They are particularly robust and perfectly suited for mounting directly onto an aluminum fence without a mounting plate.

Figure 3: Pickup tool for 200 can lids

Figure 4: Door safety switches for pallet removal

Collaboration with Machine Safety Expert Safety System Products

For Staehle, working with SSP was a major timesaver. Thanks to the complete package, including the risk assessment and safety concept, Mr. Sauter was able to place the safeguarding of the system into SSP's hands with a clear conscience.
The company impressed with extensive consultation, clever engineering and development work on the airlock, and innovative products. Mr. Sauter is very satisfied with the system.

From the very beginning, the Safety Simplifier safety controller with wireless communication was inspiring. Thanks to wireless communication and the simple connection
of the safety switches, a large part of the wiring could be eliminated.
Programming the safety controller was incredibly easy thanks to pre-programmed safety functions. The system could be plugged in directly
and was thus almost ready for use.

Figure 5: Wireless Safety - wireless communication from the control cabinet to the safety technology

The decentralized structure creates enormous flexibility should the system ever be expanded. Since communication takes place wirelessly and validation is supported by the software, in the event of an expansion, the new Safety Simplifiers only need to be paired with the system and added to the software.

Figure 6: Safety Simplifier – Decentralized safety controller