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Extending stability limits by designed-in damping

Daghini L., Archenti A., Osterlind T.

Journal of Machine Engineering

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2013

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Vol. 13, No. 1

37--48

EN

With advances in material technology come challenges to productivity. New materials are, in fact, more difficult to machine with regards to tool wear and especially machine tool stability. This paper proposes to extend the stability limits of the machining system by enhancing the structures damping capability. The aim of the research work presented here is to introduce a unified concept based on the distribution of damping within the machining system components exploiting the dynamic properties of the existing joints. To maintain a high level of static stiffness, it was chosen to adapt hydrostatic clamping systems to the tools. Damping is designed in the structure via high damping interfaces (HDI), intentionally introduced interfaces where the damping ratio is enhanced by introduction of viscoelastic polymer metal composites between the two metallic surfaces composing the interface. In this paper HDI are introduced at two joints, between tool and turret and between turret and lathe. The tests show that the designed-in damping is effective and allows extending the stability limits of the machining system. The implementation of designed-in damping allows the end user to select the most suitable parameters in terms of productivity avoiding the hassle of tuning the devices, having to acquire a deep knowledge in structural dynamics or having to use additional control systems. In addition to this, the enhanced machine tool system becomes less sensitive to stability issues provoked by difficult-to-machine materials or even fluctuations of the work material properties that might occur in everyday production processes.

2

Elements of design of production systems - methodology of machine tool selection in casing-class FMS

Świć A., Gola A.

Management and Production Engineering Review

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2010

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Vol. 1, No. 2

72-80

EN

The work presents a new methodology of computer aided FMS machine tools selection. Flexible manufacturing systems (FMS) are systems which allow manufacturing of parts in small lot sizes, keeping a high level of productivity and low costs of production. Despite the fact that applied research on designing FMS systems has been continued for several years, there are no methodological solutions that can help design engineers to select machine tools for FMS in an optimal way. This article shows the main stages of the methodology which is based on computer database systems, as well as the principles of elimination and optimisation.

3

Application of unconventional materials on primary structural parts of machine tools

Smolik J., Kulisek V.

Journal of Machine Engineering

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2009

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Vol. 9, No. 2

93--105

EN

The paper is mainly focused on possible domains of application of composite sandwich materials in the field of machine tools. A theoretical case study analyzing the effect of application of composite sandwich materials on the dynamics of the X-feed-drive axis of the horizontal milling machine is presented. The benefits of composite sandwich materials are discussed and summarized in the context of modern machine tools and their desired static and dynamic properties. Experimental case study is also presented.

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Stick-slip modelling by SOM (self-organising map): towards the intelligent design and selection of friction surface and material in machine tool design

Naude J., Nel N., Kruger J.

Prace Naukowe Instytutu Technologii Maszyn i Automatyzacji Politechniki Wrocławskiej. Konferencje

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2000

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Vol. 76, nr 35

69-80

EN

In the designing of machine tools the absence of a detailed design procedure for selecting friction material on slideways often results in the stick-slip phenomena causing tolerance defects and undesirable motion properties. The paper describes the use of self-organising maps (SOM) to capture the tendencies of the stick-slip phenomena, according to predefined parameters, from experimental data. These tendencies are presented graphically to the designer through which the designer can analyse and predict the stick-slip properties for a given slideway set-up. Due to the intelligent data grouping properties of the SOM the graphical interface produces areas of "acceptable" and "unacceptable" stick-slip properties according to the designer's stick-slip criteria for the current slideway design. The above results in the correct friction material selection and slideway surface finish for a certain stress on the friction material. The system tested in industry proved to be very successful and is currently under further development to include an expert system for more detailed design by various graphical interfaces.