Wyniki wyszukiwania - Biblioteka Nauki

1

Development of an adaptronic spindle for a faultless machining of homogeneous and inhomogeneous materials

100%

Dobrinski A. , Möhring H.-C. , Stehle T.

Journal of Machine Engineering

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2021

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tom Vol. 21, No. 2

5--23

EN

One of the latest topics in construction concerns the difficulty of producing faultless drill holes in parts made of composite and sandwich materials. At the Institute for Machine Tools of the University of Stuttgart, a prototype of an adaptronic drilling spindle for a machining of components made of homogeneous and inhomogeneous materials was developed within the framework of a research project, funded by the Federal Ministry for Economic Affairs and Energy. The spindle made it possible to limit the axial force and the torque acting on the tool, thus protecting the tools and the workpieces from any possible damage. The tests carried out with the spindle prototype proved that the axial feed force acting from the spindle can be reliably controlled by means of the developed spindle. It might be possible to restrict critical machining situations arising due to the removal of drill chips or the reduction of process temperatures.

2

Lightweight machine enclosures for dynamic and efficient production processes

100%

Möhring H.-C. , Stehle T. , Schneider M.

Journal of Machine Engineering

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2019

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tom Vol. 19, No. 2

46--53

EN

Usually machining centres for processing wood-based and composite materials have moving partial machine enclosures in the X-axis direction. Because the workpieces to be machined are often large (e.g. aircraft doors), these partial enclosures have prevailed on the market compared to voluminous complete enclosures. Owing to the general trend towards complete machining through process integration, an increasing number of additional units are integrated into machining centres in addition to the main spindle. This leads to an increase of the mass to be moved as well as a larger and thus heavier partial enclosure. This inevitable increase in mass leads to a deterioration of the dynamic properties of the machine. To counteract this increase in mass, the use of lightweight design materials for machine enclosures becomes in the focus of attention. The lightweight materials to be used must comply with the requirements of modern mechanical engineering and legislation: retention in the event of tool breakage, reduction in the noise exposure of the machine environment and cost-effective solutions compared to the materials used nowadays. The sheet steel used today as material for partial enclosures is therefore to be supplemented or replaced with suitable lightweight design materials. Different lightweight materials are qualified for suitability as machine enclosure. Apart from mass reduction, ecological as well as economic aspects of the used materials play an important role. For this purpose, the safety properties (impact resistance in case of tool breakage / collision) of these weight-reduced materials have to be determined. In addition, an improvement in the acoustic behaviour of the machine is achieved by the new lightweight materials since the machine enclosure shields the distinctive sound sources.

3

A study of low-frequency vibration-assisted bandsawing of metallic parts

100%

Tandler T. , Stehle T. , Möhring H.-C.

Journal of Machine Engineering

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2023

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tom Vol. 23, No. 2

110-122

EN

Sawing is often the first work step in the metal cutting production chain. Especially for larger workpieces, bandsawing is used for this purpose. Nevertheless, studies on sawing have led a niche existence in the research landscape for a long time. However, as a result of the optimization of manufacturing processes in terms of economic efficiency, bandsawing is increasingly becoming the focus of research, since there are still saving potentials here. The aim of this paper is to investigate the extent to which the bandsawing process can be influenced by active, low-frequency vibration superimposition in the feed direction. First, analogue tests were carried out and parameter combinations were determined which have a positive influence on the process. Subsequently, these parameter combinations were investigated on a real sawing machine with an excitation unit, analysing the extent to which the results from the analogue tests could be transferred to the real process.

4

The additive-subtractive process chain – a review

88%

Moehring H.-C. , Maucher C. , Becker D. , Stehle T. , Eisseler R.

Journal of Machine Engineering

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2023

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tom Vol. 23, No. 1

5--35

EN

In recent years, metal additive manufacturing developed intensively and became a relevant technology in industrial production of highly complex and function integrated parts. However, almost all additively manufactured parts must be post-processed in order to fulfil geometric tolerances, surface quality demands and the desired functional properties. Thus, additive manufacturing actually means the implementation of additive-subtractive process chains. Starting with the most relevant additive processes (powder-based PBF-LB, LMD-p and wire-based WAAM and LMD-w/WLAM), considering intermediate process steps (heat treatment and shot peening) and ending up with post-processing material removal processes (with defined and undefined cutting edges), this paper gives an overview of recent research findings with respect to a comprehensive scientific investigation of influences and interactions within the additive-subtractive process chain. This includes both the macroscopic geometric scale and the microscopic scale of the material structure. Finally, conclusions and future perspectives are derived and discussed.

5

Prediction of the shape accuracy of parts fabricated by means of FLM process using FEM simulations

88%

Möhring H.-C. , Stehle T. , Maucher C. , Becker D. , Braun S.

Journal of Machine Engineering

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2019

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tom Vol. 19, No. 1

114--127

EN

The prediction of component properties from the Additive manufacturing (AM) process poses a challenge. Therefore, this paper presents the development of a novel machine data (G-Code) based procedure as well as its programming implementation of a process simulation in ANSYS Mechanical for the fused layer modelling (FLM) process. For this purpose, an investigation of additively produced components with varying parameters made of polylactic acid (PLA) is carried out and simulated by means of the developed method. Application of the developed method makes it possible to predict the thermally induced distortion of PLA-Parts based on the machine data from the FLM process before production.