Wyniki wyszukiwania - BazTech

1

Numerical flow simulation of rotating circular saw blades for the investigation of sound generation mechanisms

Möhring H.-C., Stehle T., Güzel K., Zizelmann C.

Journal of Machine Engineering

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2018

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Vol. 18, No. 1

61--71

EN

Emission of airborne sound in the production industry is endangering the employees’ health and is lowering productivity. Circular saw blades in particular cause high sound pressure levels. Therefore, the tool geometry of saw blades should be improved in the sense that the emission of airborne sound is lowered. In this work, the basics for the tool optimization regarding the emission of airborne sound are elaborated. To avoid high costs for various prototypes and experimental investigations, a computational fluid dynamics (CFD) simulation is used. By this, the effects of the adjustments of the geometry on the fluid mechanics can be researched efficiently. Using the acoustic analogy of Ffowcs-Williams/Hawkings, the results of the numerical flow simulation are converted into the sound pressure level. To validate the calculated results, previously conducted experiments are used for comparison. The calculated results correspond well to the values from the experimental measurements. Hence, it is possible to use the developed method to predict the influence of geometry adjustments on the acoustic behaviour, making the optimization process possible. In an outlook, the concept for an optimization loop is explained, which couples the CFD simulation with a parameterized geometry model and an evaluation algorithm.

2

Measuring the dynamic twisting behaviour of saw blades in the kerf during the sawing process

Albrecht D., Stehle T.

Journal of Machine Engineering

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2016

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Vol. 16, No. 3

75--87

EN

Vibrations may occur in all kinds of production processes. Particularly the kinematics of band saws with their thin and unstable structure of the saw blade causes high vibrations, which generate, on the one hand, a high acoustic level. On the other hand, the impact can be seen as grooves on the surface of the workpiece. To optimize the sawing process, the vibration behaviour of the saw blades is investigated by experiment on a test band saw with a contactless measuring system during the sawing process of steel. The focus here is on the twisting of the saw blade in the kerf. The sawing parameters of cutting speed and feed rate are varied here in a wide range to examine the stability of the process and the occurring displacement of the saw blade. The results of this investigation indicate that the saw blade in the kerf shows a characteristic behaviour, which is subject to the cutting parameters. It is obvious that the performance of the process depends not only on the cutting process but also on the tensile state of the saw blade affected by the design of the saw frame, the saw blade guides and the saw blade tension. The results obtained are able to support future developments and identify an optimization potential for the sawing process.

3

Experimental Investigation into Parameters Influencing Roll Tensioning of Circular Saw Blades

Heisel U., Stehle T., Ghassemi H.

Journal of Machine Engineering

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2015

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Vol. 15, No. 1

98--111

EN

Circular saw blades are rolled in the shape of a ring by special roll tensioning machines to improve the static and dynamic behaviour of steel saw blades. Plastic deformation and strain hardening in the roller track area cause residual stresses in the circular saw blade, which influence the static stiffness and the natural frequencies of the circular saw blade. Roll tensioning is one of the important parts when producing circular saws, especially in the production of thin circular saw blades. Although the influence of the roll tensioning process on the static and dynamic properties is well-known, it is interesting to further investigate the parameters influencing the roll tensioning process. This paper presents the influence of various parameters on the roll tensioning process, such as material properties, rolling force, contact condition between roller wheels and circular saw blade. These investigations help to find the optimisation ability of this process and to gain a better understanding of the relationships between roll tensioning processes and improved static and dynamic properties of thin saw blades.

4

Development of characteristic numbers for evaluating maintainable designs

Heisel U., Stehle T., Schleich B.

Prace Naukowe Instytutu Technologii Maszyn i Automatyzacji Politechniki Wrocławskiej. Konferencje

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2003

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Vol. 84, nr 41

35-44

EN

As preliminary investigations by the Institute for Machine Tools confirm, practical experiences of the users show that the maintainability often plays a secondary role in the development and the design of machining systems. The reasons for that are various. In the absence of suitable characteristic numbers, the economic benefit of a maintainable design is difficult to quantify for practical application. The paper is concerned with a possible approach to the economic evaluation of machine assemblies and components such as main spindle, feed drives with guides and pallet changing system, also with regard to the expenditure on their maintenance. With the help of the LCC equations (optimization of the life cycle costs for machines and machining centres [1]), the costs of the life cycle phases are determined by using the example of a pallet changing system (see Chapter 2) of a medium-sized machining centre. The comparison demonstrates that improving the maintainability in designing offers economic advantages, resulting in corresponding reductions in maintenance costs. In addition, this paper presents a procedure for drawing up a design catalogue for maintainable development and design by using the example of a chip collection system (suction hood close to tool) developed at the IfW.

5

Stand der Technik und Potentiale de HSC-Technologie

Heisel U., Stehle T.

Postępy Technologii Maszyn i Urządzeń

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1998

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vol. 22, nr 4

59-77

PL

Opisano możliwości i zastosowanie obróbki z dużymi prędkościami (HSC). Przedstawiono stan wiedzy dotyczący zastosowania tej technologii do obróbki materiałów wykorzystywanych w różnych dziedzinach przemysłu. Dokonano przeglądu obrabiarek spełniających wymagania technologii HSC. Wskazano, że do HSC mają zastosowanie również heksapody - obrabiarki o nowoczesnych, niekonwencjonalnych rowiązaniach konstrukcyjnych.