Developing a toolmaking system that is expressly intended to be a model for others, is a demanding task. Only the most modern machines with intelligent control technology can be considered. At such a high level, a significant amount of engineering is required.
In order to secure the Mercedes-Benz plant in Sindelfingen as a site for development, technology and expertise, Daimler AG is also investing in this equipment centre with an additional building on Tübinger Allee, which is known internally by the abbreviation "TübA". It was here that in 2015 the new "production cell 3" was created – as a try-out centre, where sheet metal forming tools for the outer shell of vehicles can not only be manufactured but also tested straight away.
In addition to the fundamental requirements of Daimler for maximum accuracy, reliable processes, environmental protection and energy efficiency, Centre Manager Günter Sprecher set clear objectives for the project: "The new technology factory is intended to serve as a model for other toolmakers. And the equipment centre will in turn play a key role in the technology factory, because toolmaking and systems engineering skills can be bundled here." To implement all the requirements, all the project participants had to break new ground, as many new functions relating to the machine and control technology had to be developed in the process.
Modern, more modern – production cell 3
Kinematic measurement increases process reliability
Machines with interchangeable milling heads have complex kinematics. If, due to a temperature difference for example, there is uncertainty regarding the machine accuracy, or if particularly delicate or high-precision machining is planned, the automatic kinematic measurement of the milling heads provides the necessary process reliability. Based on the new C9960 measuring cycle made by Siemens, Droop+Rein developed a measuring and checking cycle for all milling heads available on the machine, which is easy and safe for the machine operator to use. The measurement of the machine kinematics is performed quickly, precisely and without a service call-out or special equipment. With the machine's standard measuring probe and a high-precision ceramic calibration ball, the machine operator is able to reproducibly qualify a milling head in less than an hour. Change the measuring probe, put on the calibration ball, call up the program, execute the automated process, check the results, adopt the correction values if necessary – and it's finished! For new system applications, such as the implementation of this extended kinematic measurement, what are called kinematic chains are required in the control system. These are a standardised declaration of the kinematic structure. Although they sound abstract and remain in the background for the user, they facilitate the realisation of other future functionalities, therefore making the machines future-proof.
Environmental protection and energy efficiency
The equipment of the new production cell 3 should not only ensure faultless and highly productive performance of the actual machining tasks; environmental protection and energy efficiency were other important issues in project implementation. The high requirement of the Daimler overall project management led by Ulrich Funk that energy consumption should be reduced by 40 percent was successfully achieved through intensive project work on the part of all the participants. Everything had been thought of from the LED lighting on the machine and the fitting of the machines with Siemens high-efficiency asynchronous motors of energy efficiency class IE3, right through to the idle power compensation. The latter is not simply a conventional, one-off, predefined idle power compensation. Instead, it automatically responds to different load statuses of the machine, which are produced with each activation or deactivation of swarf conveyors, units, etc. The idle power is therefore compensated automatically, permanently and almost completely. Ulrich Wiehagen: "In this way, the electricity consumption is optimised and the energy costs are limited to almost the active power."
