Friedrich Bleicher

Interdisciplinary Strategies for Simulation-Based Optimization of Energy Efficiency in Production Facilities

This paper presents an approach for interdisciplinary optimization of energy efficiency in production plants. Domain-specific areas of action are discussed as well as the integration into a dynamic co-simulation that helps predicting the impact and financial benefit of selected energy saving measures by comparing and quantifying different scenarios. This should help giving incentives and creating impulses for strategic investment decisions. In a comprehensive methodological approach, optimization potential of both the production process itself as well as the production infrastructure is combined. The technical implementation involves several simulation environments and a framework for synchronization and data exchange in terms of co-simulation. The paper concludes with a discussion of some exemplary simulation results.

Improving wear resistance of functional surfaces using the machine hammer peening technique

Abstract Machine hammer peening (MHP) is a novel surface treatment technology, which creates smoother surfaces with a local hardness increase and compressive residual stresses well below the surface. By these means, properties of functional surfaces can be enhanced, which opens a broad range of potential applications, especially for surfaces undergoing tribological contact. In the present work, two commercially available steels are processed using the MHP technique. Additionally, the technique is applied as a tool for embedding hard particles into the surfaces of samples. The tribological performance of the MHP processed samples is investigated under reciprocating sliding conditions using a ball-on-flat configuration. The wear resistance of the samples is analysed using optical and white light confocal microscopy methods. The results show a significant increase in terms of wear resistance for MHP samples with embedded hard particles.

Enhanced Sliding Wear Resistance of Technical Alloys by Hard Particle Reinforcement Using Machine Hammer Peening

ABSTRACT Machine hammer peening is a surface treatment technique originally developed for smoothening tools and mold surfaces. Treated surfaces are locally cold-worked, which results in a hardness increase and the induction of compressive residual stresses. In the present work, the feasibility of using this technique as a tool for embedding tungsten carbide hard particles on engineering-relevant substrate materials is systematically investigated. Tungsten carbide particles of three different sizes were embedded onto selected substrates using machine hammer peening. The particle embedment quality of the engineered surfaces was evaluated and correlated to the substrates mechanical properties. The resulting tribological performance was investigated under reciprocating sliding conditions and the dominant wear mechanisms were correlated with the diameter of the embedded particles. The results show that machine hammer peening is a suitable technique for embedding hard particles in substrates of various materials, which additionally results in an enhancement in wear resistance, thus opening up a wide range of potential applications in tribologically loaded surfaces.

New Design of a Bimetallic Finned Tube for the Use in Latent Heat Thermal Energy Storage Units

The use of finned tubes as enhancement method to increase the heat flow rate into a phase change material, which has in many cases a low thermal conductivity, is a common method. A highly efficient and easy-to-assemble solution for finned heat exchanger tubes is a key component for innovative thermal energy storage systems which play a key-role in electricity production and industrial heat management.In the present article the results of the investigation for different designs of bimetallic heat exchanger tubes is presented. These tube designs are developed for the use in latent heat thermal energy storage systems (LHTES) at a medium temperature range. For the use in latent heat thermal energy storage systems, the probably high pressure of the heat transfer medium and the high temperature differences between the operating temperature and the ambient temperature are challenging. Therefore, the bimetallic finned heat exchanger tube consists of a steel tube, where the heat transfer fluid flows, and an aluminum tube with longitudinal fins, which should improve the heat transfer to the phase change material. Due to different thermal expansion coefficients, displacements of the tubes are given. To guarantee a high heat transfer rate between the two connected tubes the contact between aluminum and steel plays an important role.In the present study 4 prototypes (including the new design) were designed, analyzed and compared on the connection strength. Long-term tests for simulating the application in a LHTES were done to determine the creep rupture properties of the compositions. All prototypes were tested successfully; the new design is convinced in many aspects of that challenge and is submitted to the Austrian patent office. Main advantages of the new design are the simple production and assembling compared to other analyzed prototypes. Furthermore, the new design shows the best results under the analyzed operation conditions and the layout of the geometry has a high optimization potential in terms of stresses.Copyright

Some Contributions at the Technology of Electrochemical Micromachining with Ultra Short Voltage Pulses

The tendency to make progressively smaller and increasingly complex products is no longer an exclusive demand of the electronics industry. Many fields such as medicine, biomechanical technology, the automotive, and the aviation industries are searching for tools and methods to realize microand nanostructures in various materials. The microstructuring of very hard materials, like carbides or brittle-hard materials, pose a particularly major challenge for manufacturing technology in the near future. For these reasons the Institute for Production Engineering and Laser Technology (IFT) of the Vienna University of Technology is working in the field of electrochemical micromachining with ultra short voltage pulses (μPECM) in nanosecond duration. With the theoretical resolution of 10 nm, this technology enables high precision manufacturing. [Kock M.]. A question, which can illustrate the motivation to do this research work in this field, is: “Which parameters have to be set at a production machine and which framework conditions have to be managed to reach a desired result?” To answer this question for the materials nickel and steel (1.4301), the IFT has done experimental work.

Using coupled simulation for planning of energy efficient production facilities

To meet the increasing requirements of sustainable production and to assure economic competitiveness, novel strategic approaches are necessary in designing production systems and to increase energy efficiency in the manufacturing industry. Individual areas within production facilities (e.g. production system, energy system, building hull) can be analyzed individually by using simulation-based methods. In order to access additional optimization potential, it is necessary to expand the boundaries of such simulations and to consider dynamic interactions between individual optimization fields. This work presents an approach for an interdisciplinary co-simulation, in which, for an overall integrated simulation, several simulation environments are coupled that periodically exchange data quasi-parallel at runtime. This allows not only to combine different model descriptions, but also multiple calculation algorithms, each specifically tailored to the individual needs of the respective field of engineering. A case study of a metal-cutting production facility presents an application example. The goal is to provide a decision-support tool for the early planning stages of production facilities that allows making qualified predictions about the effect and financial impact of different energy saving measures.

Weighted Euclidean distance-based approach as a multiple attribute decision making method for manufacturing situations

The selection of appropriate alternative in the manufacturing environment is a very important but at the same time a complex and difficult problem because of the availability of wide range of alternatives and similarity among them. So, there is a need for simple, systematic, and logical methods or mathematical tools to guide decision makers in considering a number of selection attributes and their interrelations. In this paper, a new multi-attribute decision making (MADM) method, ‘weighted Euclidean distance-based approach (WEDBA)’ is developed and applied to various decision making situations of the manufacturing environment. The method considers the objective weights of importance of the attributes as well as the subjective preferences of the decision maker to decide the integrated weights of importance of the attributes. Furthermore, the method uses fuzzy logic to convert the qualitative attributes into the quantitative attributes. Four examples are presented to illustrate the potential of the proposed WEDBA method and the results are compared with the results obtained by using other decision making methods.

Vibration assisted drilling of CFRP/metal stacks at low frequencies and high amplitudes

In many applications of automotive and aircraft industries the use of material combinations such as compound materials made from carbon fiber reinforced plastics (CFRP) and metal materials like steel, titanium or aluminum alloys is significantly increasing. For these industries, the lightweight and mechanical properties of the reinforced plastic materials gain more and more importance. When machining material combinations, a number of distinctive material related effects occur and hamper the straight-forward implementation of machining processes. These effects mainly derive from the distinctive chipping behavior of the material combination caused by the different material characteristics. Thus, the drilling process of CFRP/metal stacks is to be regarded as a challenging task due to the requirements of machining efficiency and quality aspects. In this regard, vibration assisted drilling at low frequencies but high amplitudes opens up significant opportunities for improvements of the machining processes. The feed rate is superimposed by a controlled harmonic motion in order to create an intermittent cutting state. The potential of vibration assisted drilling lies in the reduction of cutting forces and tool wear.

IN-PROCESS CONTROL WITH A SENSORY TOOL HOLDER TO AVOID CHATTER

Hydro-, steamand gasturbines, aircraft components or moulds are milled parts with complex geometries and high requirements for surface quality. The production of such industry components often necessitates the use of long and slender tools. However, instable machining situations together with work pieces with thin wall thickness can lead to dynamic instabilities in the milling processes. Resulting chatter vibrations cause chatter marks on the work piece surface and have influence on the tool lifetime. In order to detect and avoid the occurrence of process instabilities or process failures in an early stage, the Institute for Production Engineering and Laser Technology (IFT) developed an active control system to allow an in-process adaption of machining parameters. This system consists of a sensory tool holder with an integrated low cost acceleration sensor and wireless data transmission under real time conditions. A condition monitoring system using a signalprocessing algorithm, which analyses the received acceleration values, is coupled to the NCcontrol system of the machine tool to apply new set points for feed rate and rotational speed depending on defined optimisation strategies. By the implementation of this system process instabilities can be avoided.

Machining of Difficult-To-Cut Materials

Austenitic steels are used in different areas of application where high strength and corrosion resistance are necessary at low and intermediate temperature levels. Machining these materials therefore induces high mechanical and thermal loading and reduces tool life and the overall process performance. A well-known approach to raise tool life is to dissipate the heat from the cutting edge. This paper presents some findings of a combined externally and internally cooled cutting insert compared to a solely externally cooled cutting insert.