E-mobility, digitalization and automation - these are just some of the trends that are currently shaping the field of grinding technology. Exhibiting companies at the new GrindingHub trade fair and research experts will provide insights into current technologies and processes in this particularly demanding industry.
E-mobility is changing the entire drivetrain in cars. Transmission parts must be ever more precise, lighter and more robust. Liebherr-Verzahntechnik GmbH has dealt intensively with the requirements of e-mobility. Methods for flank line modification minimize noise development and optimize load capacities. Here in particular, generating grinding with dressing-free CBN grinding worms can be an economical alternative to corundum grinding worms. It is process-reliable, ensures long tool life and significantly reduces measuring and testing costs.
The grinding process and clamping technology must be fast and highly precise for the production of delicate e-bike transmission parts. With special clamping solutions, even small and collision-critical components can be machined without any problems. The exclusive Liebherr machine concept with a single-table solution achieves optimum concentricity and high reproducibility - for the production of parts with quality requirements in the micrometer range. The choice of the right process ultimately always depends on the specific requirements. Liebherr can test all process parameters on its own test machines. "There is often no 'right or wrong'," explains Dr. Andreas Mehr, gear grinding expert. "As a partner and solution provider, we advise customers and show them alternatives so that they can make the best decision in the end - including at GrindingHub 2022."
Process monitoring during generating grinding of electric gear teeth
Photo: Liebherr VerzahntechnikGearboxesfor electric cars are simpler in design than those of conventional combustion engines, but place much higher demands on the manufacturing accuracy of the gears. In addition to speeds of up to 16,000 rpm, electric motors deliver a constant torque over a wide speed range. There is also another constraint, explains Friedrich Wölfel, Head of Machine Sales at Kapp Niles: "A combustion engine masks the transmission noise. An electric motor, on the other hand, is virtually silent. At speeds above around 80 km/h, rolling and wind noise are the dominant factors, regardless of the drivetrain. But in the range below this, transmission noise can be disturbing in electric vehicles." For the fine machining of these components, it means implementing a generating grinding process that is equally productive and, above all, optimized in terms of the noise behaviour of the ground gears. In particular, so-called "ghost frequencies", which can be introduced into the component during grinding due to unfavorable machine and process design, must be avoided.
Since the machining of a gear wheel takes considerably less time than the control measurement during generating grinding, it is not possible to inspect 100 percent of all components. The approach is therefore to identify possible errors during the grinding process. Process monitoring is the keyword. "We already have numerous sensors and measuring systems in the machine that provide us with a lot of signals and information," explains Head of Advanced Development Achim Stegner. "We will use these to assess the machining process and therefore the expected quality level of each individual gear directly in the generating grinding machine in real time. For noise-critical components, an order analysis similar to an end-of-line test bench can be created.
Gear grinding will therefore provide significant added value in the future to ensure the quality requirements of these components. As an exhibitor at GrindingHub, we are looking forward to the innovative concept of the trade fair."
Developments in tool grinding technology
The challenges in the field of tool grinding are constantly increasing. On the one hand, more and more special tools are being produced in small batch sizes, meaning that the process design right up to the first good part is becoming more and more economically relevant. On the other hand, existing series processes need to be continuously optimized in terms of their robustness and productivity so that they can hold their own against international competition, even in high-wage countries. The Institute of Production Engineering and Machine Tools (IFW) in Hanover is pursuing several research approaches. The first step is to support process design by simulating the tool grinding process. The simulation makes it possible to predict the displacement of the ground blanks caused by the process force even before the first cutting tool is manufactured, so that this is compensated for during grinding and the resulting geometric deviations are avoided. Furthermore, an analysis of the load occurring on the grinding tool is carried out so that the process planning can be ideally adapted to the grinding tool used. As a result, the machining result is improved and the production of reject parts is minimized.
"In order to maintain the increased machining quality even with higher quantities, laser-based sensor technology was also installed in the machine tool to measure the grinding wheel topography," explains Managing Director Prof. Berend Denkena, who is also active on the board of the WGP (Wissenschaftliche Gesellschaft für Produktionstechnik). "This allows continuous evaluation of the grinding tool condition and can therefore be used for process-specific dressing intervals. Wear-related deviations in the workpiece geometry and the associated rejects can therefore be avoided."
Automation + digitalization
"The pace of development within grinding technology has increased significantly in recent years. The advances in digitalization are largely responsible for this," says Dr Stefan Brand, Managing Director of the Vollmer Group from Biberach, commenting on the trends in grinding technology. "At Vollmer, we have been using digitalization for automation and data analysis for years and have developed our own IoT gateway, which we are increasingly feeding with data. The latest trend for grinding technology is the further integration of process data. With this knowledge, the user can gain interesting insights to optimize the grinding process. The journey into a digital future is constantly evolving: we are seeing a trend where the integration of classic grinding technology with digital functions is not only influencing the grinding process itself, but also changing the grinding technology market. Whether sharpening service, tool manufacturer or global production company - digital and automated processes are being used as a lever for optimization. This development is one reason why the new GrindingHub trade fair will focus on automation and digitalization in grinding technology in addition to the areas of technology/processes and productivity. We therefore welcome the opportunity to present our grinding technology to a broad and international audience at GrindingHub."
