Virtually developed, precisely controlled
The machine manufacturer Kellenberger Switzerland AG has replaced the controls of the Kellenberger T1000 cylindrical grinding machines with the current Sinumerik One. The CNC control, together with other Siemens components, ensures precise grinding processes.
Accurate to a tenth of a micrometer
When Kellenberger consolidated its four previous Swiss subsidiaries in an impressive new building, production of the Kellenberger T1000 cylindrical grinding machines moved from the Bern region to eastern Switzerland. Stäheli explains: "The modular cylindrical grinding machine 'Kellenberger T1000' is specially designed for the highly productive manufacturing of specific components. While universal grinding machines are constantly retooled during operation, we develop and manufacture each T1000 specifically for a particular component – e.g., hydraulic cylinders for valves in the automotive or aerospace industry."
The material is removed with grinding wheels coated with diamond or corundum. Before, during and after this process, measuring probes control the position of the grinding wheel. This allows the required accuracies of up to 1 micrometer and smaller to be achieved. For comparison: A human hair with a diameter of 80 micrometers is 80 times thicker. The axes of the Kellenberger T1000 are hydrostatically supported. A thin oil film prevents direct contact between the guides, thus reducing wear and dampening vibrations. The automatic oil pressure control precisely levels the system, ensures uniform axis movements and enables the highest dimensional accuracy when grinding.
Precisely controlled with Sinumerik One: In cylindrical grinding, the required accuracy is sometimes in the tenth of a micrometer range.
To avoid rejects with expensive workpieces, Kellenberger relies on the uninterruptible power supply Sitop.
The mobile Sinumerik HT handheld device is helpful for setting up the machine or making adjustments.
The Kellenberger T1000 cylindrical grinding machine from Kellenberger stands for precise and fast single-purpose manufacturing and is typically not retooled during operation.
High efficiency through parallel implementation
After project migration to TIA Portal, the AVM team used the self-developed tool "TiaExchange" to export the entire project via an Openness interface into open text files. This allowed all adjustments to be seamlessly documented in a version control system. "The great advantage of this so-called source code management was that our development team and AVM could work in parallel," explains Stäheli. "This made us faster, required fewer on-site meetings and allowed us to ensure high quality requirements at all times."
During the construction of the first of four machines with the new control, the specialists from Kellenberger and AVM cleaned up the interaction between the programmable S7 controller and Sinumerik, integrated the new operating elements, the machine control panel and the handheld device. With the software "Create MyVirtual Machine" (CMVM) and the newly created PLC-IO simulation, all functions in Sinumerik One up to Safety and Human-Machine Interface (HMI) with integrated Display Manager could be tested before the machine was completely assembled. The resulting digital twin will continue to be updated regularly in the future and can provide valuable services for adjustments, e.g., if the machine should ever produce a different component in the future.
The project took almost two years in total. The switch to the new control brings joy: "The TIA environment offers significantly improved configuration and diagnostic capabilities and we are extremely satisfied with the performance, precision, process monitoring and safety functions of Sinumerik One," emphasizes Stäheli. "We are pleased that Kellenberger can now also offer its process-specific machines with Sinumerik One control."
Thanks to the digital twin, Kellenberger was able to equip several cylindrical grinding machines with the current numerical control Sinumerik One in a short time.
Simple operation: Multiple operator interfaces – including those from third-party providers – can be clearly displayed on the Siemens HMI.
Updating the NC control to Sinumerik One brings numerous advantages. The digital twin and valuable diagnostic capabilities in TIA Portal are among them.
In cylindrical grinding, material is removed with a rotating grinding wheel to achieve precise diameters, surface qualities and roundness.