Prof. Steffen Ihlenfeldt
Technical University Dresden, Germany
Thermo-energetic design of machine tools
Advanced, high strength materials and new machine tool technology increase cutting power, which requires higher energy input and causes larger thermal losses in machining operations. As a result, thermally induced defects increase and the expensive necessity to keep them within limits puts the economic efficiency of the production at risk.
To address this challenge, the collaborative research center SFB/TR 96 was established. It explores methods for maintaining full control over the machining process despite rising power losses, unsteady ambient temperature settings, and operating conditions of single as well as small batch production without additional energetic measures.
The researchers of SFB/TR 96 conducted basic investigations on methods for correction and for compensation of thermal errors on simplified structures and applied them to machine tool sub-assemblies. In the current phase, the research efforts encompass the entire machine tool under real production conditions. These holistic considerations entail large numbers of uncertainties and parameter fluctuations, which require new numerical approaches and data acquisition methods.
The keynote speech will elaborate on how factoring in process data and a large number of assemblies increases the accuracy of transient temperature distribution models and how these methods are adapted to the requirements of the design phase (generalized load data) and the operating phase (real-time data).
The second part will point out exemplary or lifetime fluctuating parameters as cause of remaining deviations between simulation and measurement and show how model enhancement, e.g. solutions for model tracking and online model monitoring address this issue.
Subsequently, the talk introduces methods how to manage the increasing complexity (e.g. position dependence of thermal effects) and how to implement advanced boundary conditions such as cooling lubricants and chips into simulation models. This comprises the analysis of the interactions between different machine-internal influences (process as well as fluid, drive and motion systems) and the interaction with thermal environmental influences on the machine.
Finally, the talk discusses methods for using the CNC program to influence the temperature field and the evaluation of potential combination of correction and compensation solutions.
The SFB/TR 96 is on the way to break the trade-off between energy consumption, machining accuracy and productivity.
Prof. Dr.-Ing. Steffen Ihlenfeldt, born 1971 in Aschersleben, studied Mechanical Engineering at the Technische Universität Braunschweig from 1991 to 1997. From 1997 to 1999, he worked as a research assistant in the Department of Machine Tools at the Fraunhofer Institute for Machine Tools and Forming Technology IWU. From 2000 to 2015, he held various management positions at the Fraunhofer IWU Chemnitz, most recently as Head of the Machine Tool Department in the Main Department Machine Tools and Automation.
In 2015, Prof. Ihlenfeldt took over as head of the Chair of Machine Tools Development and Adaptive Controls at the Institute of Machine Tools and Control Engineering (IWM) – now the Institute of Mechatronic Engineering (IMD) – at Technische Universität Dresden, thus replacing the former director Prof. Dr.-Ing. habil. Knut Großmann. Since 2016, Prof. Ihlenfeldt has also been head of the Department of Cyber-Physical Production Systems (CPPS) at Fraunhofer IWU Chemnitz. Furthermore, he is Corporate member of the International Academy for Production Engineering (CIRP) for the Fraunhofer IWU and member of the German Academic Association for Production Technology, WGP.
Prof. Konrad Wegener
ETH Zürich, Switzerland
Hot topics in thermal compensation of machine tools
The machine tool of the future will be capable of ultra-precision manufacturing under job shop conditions. Energy efficiency gains importance not only as such, but due to the fact that any energy supplied to the machine tool needs to be extracted and is the origin of temperature gradients. An efficient approach takes into account all information available, computes correction values and uses also available actors for influencing the deviations on the workpiece. Countermeasures to thermal displacements involving sensory and actors and a model based control system in between can be considered as a morphological box. Different modelling approaches distinguished in the degree of experimentation versus modelling effort are discussed. This ranges from complex and detailed physical modelling down to phenomenological models and Neural Networks with hundreds of parameters to be defined in measuring and machine learning algorithms but their physical contents is only the history dependency. Besides internal thermal loads environmental issues play a major role and must be taken into account, despite their complexity and variability for different machines of the same type, depending on the individual placement of the machine in the job shop, but also on the coolant supply and enclosures that create a micro climate within the perimeter of the machine tool. Sensors must be chosen according to the placement conditions and also here machine learning techniques can be applied with great benefit. Solutions provided so far drastically enhance the behavior but still leave machine tools with thermal influences, and therefore required new countermeasures are discussed as outlook to future research.
Konrad Wegener is full professor and head of the IWF (Institut of machine tools and manufacturing) at ETH Zurich since October 2003 and leads the manufacturing section of the Swiss technology transfer center inspire AG. Fields of research are today optimization of machine tools, cyberphysical production systems, cutting technology, additive manufacturing, laser material processing and electro discharge machining. He is fellow of the CIRP.
After his studies in mechanical engineering and PHD in Braunschweig 1990 he began his
industrial carreer at Schuler Presses GmbH & Co. KG in Göppingen as head of design and layout planning departments. In 1999 he was charged with the general management of a newly acquired company for laser systems. Under his leadership large welding machines for shipbuilding and construction of aeroplanes, welding and cutting machines for the automotive industry and cutters for fabric have been developed and built.
Prof. Atsushi Matsubara
Kyoto University, Japan
Design and evaluation challenges in solving spindle thermal issues
To realize high speed and high stiffness machine tool spindles, design and evaluation techniques relating to thermal issues are essential. These include lubrication, bearing, motor, material, and monitoring technologies. This talk will introduce the challenges encountered in our research and development aiming for a large Dn number, reduced thermal displacement, and evaluation of the spindle's thermal stability. The first topic is the development of a high speed and high stiffness spindle for application to multi-tasking machines. The spindle, based on lean lubrication and variable preload techniques to avoid heat generation, had a maximum rotation speed of 50,000 rpm and a Dn number of 3 million. A monitoring system was also developed by integrating sensors that prevent the spindle from burning due to heat generation. The second topic is the evaluation results on a test spindle that employed a CFRP shaft to suppress thermal displacement. In this test spindle, we could compare a steel shaft directly with the CFRP shaft, and quantitatively evaluate its comparative advantages. The third topic is the development of a non-contact stiffness measuring device and its application to assessing the dynamic characteristics of rotating spindles. This non-contact stiffness measurement method makes it easy to measure dynamic changes over long running periods, and thus clarify thermal effects on the spindle stiffness.
Prof. Matsubara earned a B.Sc. degree from Kyoto University in 1985 and started his professional career as a production engineer in Murata Manufacturing Co., Ltd. While working in the company, he continued his studies at the Kyoto Institute of Technology, which granted him an M.Sc. degree in 1991. He was appointed as an assistant professor in precision engineering at Kyoto University in 1992. He obtained a Ph.D. from Kyoto University for a dissertation paper entitled "Development of Intelligent Grinding System" in 1997. He became an associate professor in 2000 and a full professor in 2005 in the Department of Micro Engineering at Kyoto University, where he is responsible for the precision measurement and machining laboratory.
Professor Matsubara is a member of the Japanese Society for Precision Engineering (JSPE), the Japanese Society of Mechanical Engineers (JSME), the Japan Society of Abrasive Technology, the international academy for production engineering (CIRP). He serves as the vice-chairman of the science technical committee "Machine" in CIRP. He had received Education Award from JSME in 2009, Numata Memorial Paper Award from JSPE in 2011, Best Paper Award from JSPE in 2017.
His research and education areas are modeling and controlling dynamic systems with applications in mechanical systems and manufacturing processes, as well as design of Intelligent systems for machine tools.
TOSHULIN , Czech Republic
Active thermal error compensation in real industrial environment
Improving the basic properties of machines, especially the accuracy and the reliability of machines and processes are among the main objectives of R&D. One of the main challenges of current manufacture is the high degree of product individualisation. In particular, advanced simulation and compensation models help reduce the risk of poor final quality and enable better utilization of the machine's production potential. However, application of research solutions into the real industry environment brings with it various difficulties, e.g. handling input parameters from appropriateness and safety point of view, implementation of solutions into control systems or effective validation within real industrial conditions, all depending on economical/ecological aspects. The outlined issues is discussed in more depth with resects to anchored principles of Industry 4.0, intelligent solutions.
Ing. Vojtěch Frkal is the technical director at TOSHULIN, a. s. He received his university education at the University of Technology in Brno. His study was focused on the construction of machine tools. He obtained his degree in 1995 at the Institute of Manufacturing Machines and Robotics. In his ongoing studies, he focused on computer support of design in mechanical engineering. He graduated in 1997 from the Institute of Solid Mechanics.
He started his career in 1995 in a small engineering company. Here he worked as a designer and later as a development manager until 1999. After that he worked shortly in the design department in the Brno branch of the Belgian company IG Wateuw. This company is engaged in the development and production of gearboxes. Gearboxes manufactured at the Brno plant are used in railway vehicles, agricultural machinery or construction machinery. Since 2000 he has been working for TOSHULIN, a. s. The company is one of major manufacturers of machine tools in the Czech Republic. It has its own design and development department. The company's products are at a high technical level and are considered to be at the forefront of the industry. Mr. Vojtěch Frkal initially worked as a designer, later he held other positions in the design department. Since 2006 he has been the head of technical support for the sale of machine tools. Here he participated in communication with customers and proposed new solutions according to their requirements. Since 2014, he has been working as a technical director. He is responsible for the development of new products, design of the mechanical part of machines, electrical HW, programming of basic SW equipment CNC, etc. He actively participates in the management of innovation and technical development. He manages cooperation with research organizations within different research projects. The company TOSHULIN, a. s. is a participant in important research projects in the Czech Republic as well as in Europe.
Dr. Ondřej Uher
Compo Tech PLUS, Czech Republic
Composite applications for thermal stable components
Carbon fiber composite applications in machine tool and machine building industry are slowly replacing conventional materials. One of the motivation for these applications is thermal stability of carbon fiber composites. Especially ultra-high modulus carbon (graphite) fiber composites can have not only elastic modulus higher than steel but also negative thermal expansion. On other hand these unique properties are function of fiber orientation. Another important parameter is thermal conductivity, where along the fiber the value can be higher than aluminium but across the fiber orientation is much worse. Thus design of machine parts with objective to apply one of above mentioned properties can be very complex. CompoTech company has several successful machine parts applications taking advantage of thermal behavior of ultra-high modulus carbon fiber, like compensation reference rods, machine tool spindle, milling tool, inspection machine beam. These will be presented and their performance discussed.
Dr. Ondřej Uher born in 1972 in Sušice, Czech Republic, studied Mechanical Engineering at the Czech Technical University in Prague (CTU) and obtained his degree in 1995. He found company Compo Tech Plus spol. s r.o. with his friend, and also CTU student Vít Šprdlík in 1994. Since that he is responsible for all research and development activities relating the main Compo Tech objective to develop and produce composite solution for industrial applications and especially the application in general machine building industry. He received his doctore degree under program of prof. Milan Růžička at CTU in 2003. The close collaboration between Ondřej Uher, CompoTech and CTU is not only the participation on many research projects, which resulted in number of successful composite applications in machine tool and machine building industries, but also in his active role in student education in the field of mechanics of composite materials.