1. Introduction
Modular, multi-branch equipment with various safety functions requires a clear structure, easy programming, and manageable safety solutions. For example, Sietatec achieved full automation of its erection equipment with the help of a complete solution provided by Pilz, enabling smooth and unimpeded operation of the production process.
For a long time, Still GmbH of Germany has remained a leading supplier of internal logistics systems such as forklifts, transport vehicles, and tractors.
In order to remain competitive in the fierce market, the company has steadily modernized its production in recent years, gradually completing the production of forklifts on a multi-branch and nearly fully automated machine.
Most of the assembled lifting components arrive at the end of the assembly line in the material buffer zone via an unmanned conveyor system. This system consists of two conveyor sections for transporting empty conveyor frames, two erecting devices, and a 32-meter-long buffer section. At the two loading stations, cranes position and secure the arriving masts onto the automatically fed conveyor frames. A ball-thread electrically driven erecting device elevates the assembly, consisting of the conveyor frames and masts and weighing up to 2 tons, from a horizontal position to a vertical position. The secured masts then pass through driven roller guides and chain conveyors into the spare area of the buffer zone, where final assembly is completed (Figure 1).
Figure 1 shows the two loading stations, where the crane positions and secures the arriving mast onto the automatically fed conveyor, and the PSS4000 automation system ensures the safety of this process.
The design and manufacture of the vertical equipment, which requires approximately 20 x 50 m of space, are both by Sietatec GmbH, located in Albersdorf, Heide, Schleswig-Holstein, Germany. The company specializes in the design and manufacture of specialized machinery in the fields of automation, manipulation, and conveying technologies. In addition, the company develops and manufactures tools and devices for clamping and positioning, and designs and writes specific software and control programs.
2. A 1000 m² safety zone
During the design process of the erecting equipment, Sietatec and Pilz jointly identified areas that could pose hazards to people and machinery. Based on the risk analysis, they developed safety measures to ensure maximum safety around the multi-branched equipment while minimizing adverse impacts on logistics access and accessibility. "We have been working closely with Pilz for many years, and because we are familiar with their product range and value their expertise, we invited them to join this project," said Rainer Ziehe, Head of Development and Design at Sietatec.
3. Unconventional and intuitive automation
The Pascal Safety Calculator makes safety function calculations easier to understand. This tool calculates safety functions based on the PL (performance level) and SIL (safety integrity level) achievable in the components and equipment used. The results are verified using the performance level required in ENISO 13849 and the safety integrity level required in EN/IEC 62061. If processing is required, the Safety Calculator will display the results.
Complex field devices with numerous monitoring and security functions require remote solutions, and Pilz's PSS4000 automation system for safety and automation became the final choice. All components of the system achieve a perfect integration of hardware, software, network components, and real-time Ethernet SafetyNETp.
Figure 2 shows Still's "CubeXX," a multi-functional vehicle that combines the functions of six vehicles into one.
With the allocation and transfer of peripheral device control functions, the PSS4000 offers greater flexibility and convenience for a wide variety of projects compared to traditional solutions. User programs achieve simple and unified processing, while the PSS4000 software platform makes configuration and programming faster and more intuitive. Tools for project configuration, programming, debugging, and operation work seamlessly together, eliminating the need for software license purchases and leaving only the essential functionality. "We believe that the modular automation system PSS4000 is easy to program, convenient to network, requires minimal space in the control cabinet, and can be easily plugged in for startup and management," Rainer Ziehe emphasized.
Figure 3 shows a complex field device with numerous monitoring and security functions that requires a remote solution; Pilz's PSS4000 automation system for security and automation became the final choice.
4. All line segments and gates possess a high level of security.
Safety technologies are installed in three control cabinets. Pilz's remote I/O system, PSSuniveral, uses two I/O modules and a total of 105 inputs and 18 outputs at the ends of the vertical equipment input segments 1 and 2 and the buffer segment to perform all control and monitoring related to safety functions. The I/O modules are interconnected via industrial Ethernet, and message notifications and equipment status are transmitted to the equipment controller via fieldbus.
The PSS4000 automation system monitors all emergency stop buttons, 13 light curtains, multiple positioning switches, and scanning detectors installed along the equipment. A special task is the monitoring of two gates: the PSS4000 monitors not only the mast conveyor within the equipment but also the lateral movement of an unmanned transport system that operates at a distance from the equipment, ensuring that no collisions occur between them during this process.
Pilz's electromagnetic safety switch PSENmag is responsible for the positioning detection of the erection device. The PSENopt grating in the gate ensures that no personnel will be injured during the erection process. In addition, an indicator light will flash when the gate is in motion.
5. Relay monitoring for drive vollePower
Sietatec specifically endorses Pilz's PNOZpower safety relay: the device incorporates 63 small actuators, with each safety relay monitoring 10 actuators and safely shutting off in an emergency. Thanks to the selection of compatible modules, the relay offers scalability and flexible adaptability, retaining only essential functions and eliminating the need for external contactors and contactor assemblies. "This technology is irreplaceable; previously, only complex relays could achieve this," said Rainer Ziehe.
Additionally, Pilz's efficient operating mode selection switch, PITmode, was installed. This switch combines two functions: it can securely switch between defined and authorized modes, and it provides various control permissions through identification management integrated into the switch. Each key has a unique personalized ID engraved on its back, which monitors traceability and accountability, determining who can perform tasks related to individuals or user groups on the machine and in what manner.
The "safety contact" integrated into the emergency stop button (PIT) ensures the button's functionality at all times.
“The collaboration between the two parties has been excellent as always: Pilz understood our needs, raised the right questions, and the implemented solution provided operators with a safe, efficient, and highly practical solution,” Rainer Ziehe concluded. Further projects with even higher requirements are yet to be completed, and Sietatec's customers will soon have access to highly sophisticated and safety-standard automation solutions.
