Machine safety for a newly developed rotating packing system
These packing systems are designed for the efficient filling of free-flowing materials, such as cement, into bags, the model range is being continuously expanded. The people responsible at Haver & Boecker used the development of the current Roto-Packer generation to fundamentally optimize the safety functions.
In view of fast movements and high loads, machine safety generally plays an important role in this area of application. As "rotary packing systems", the machines have particularly complex safety requirements: Up to 16 filling spouts rotate around a central axis. Theoretically, each individual filling station can be protected separately. However, with conventional, i.e. hard-wired, safety relays and contactors, this means high technical effort, high space requirements and, last but not least, considerable costs.
In addition, the rotation or a cycle rate of around 2,400 bags per hour require a high switching frequency of the safety relay. Until now, the specified safety standards were therefore usually met by enclosing the entire system, and safe access required or triggered a machine shutdown.
Digitalization now creates new possibilities for safeguarding each filling system individually – just as safely as with conventional safety devices, but much more efficiently. This not only facilitates access to the stopped plant. Maintenance is also made easier because, for example, a running motor can be checked with the cover open.
Software-parameterizable SIRIUS 3SK2 safety relays
In the search for a suitable solution, the SIRIUS 3SK2 safety relays from Siemens SIRIUS portfolio were chosen. Unlike conventional safety components, these can be parameterized via software and are therefore flexibly adaptable. The parameters can be quite easily transferred to other machines using a USB cable or via a fieldbus/PROFINET interface. Various safety functions can be combined in one device.
The advantages of this software-based approach over hardwired devices are enormous: The problem-free transfer of the pre-programmed parameters saves time at each individual danger point. With eight safety components installed in one Roto-Packer, the time savings add up accordingly. The overhead required for planning and wiring is also reduced enormously.
Further plus points from Haver & Boecker's point of view: The machine builder generally uses its own controls. Since the safety relays operate independently of the control system, they can also be easily integrated into this automation environment. In addition to the SIRIUS 3SK2 safety relays, SIRIUS ACT ID key-operated switches complement the safety concept. Using the electronic ID key-operated switches, individual authorizations can be flexibly assigned – this further increases personnel and plant safety.
The ability to pre-program SIRIUS 3SK2 safety relays simplifies our spare parts inventory management. So we can help the customer very quickly in the event of a failure.Michael Grollich, HAVER & BOECKER oHG