The accuracy of guiding a spindle is greatly influenced by the thermal load of the bearing. Increased thermal load implies deformation of the bearing parts which is directly reflected in the work ...quality of the machine system. For this reason, the aim of this paper is to analyse the influence of the material and the geometry of the housing on the temperature field of the threaded spindle bearing assembly, which was realised by "radially mounting" of axial angular contact ball bearing ZKLN. This paper represents a new approach for thermal analysis of the special bearings, type ZKLN which are not involved in the relevant standards for the determination of the reference speed. At the same time the value of this paper finds itself in finding of the guideline at engineering practice which is very important at early design phase of the systems with threaded spindle. The analysis was carried out using experimental and numerical methods. Combination of the mentioned methods gave result which was used to define appropriate guideline regarding influence of housing material and geometry on thermal stability of the ZKLN bearing.
The paper deals with a novel design of a combined machine tool in comparison with known contemporary analogues. It is designed for multifunctional machining of workpieces in one or two setups in ...collet and centre-to-centre design. Typical of this machine tool is the use of a bed with a trapezoidal cross-section with inclined longitudinal guides on both sides for the slides used for rough, fine and finish machining. With this design, the slides are spatially separated and lightly loaded. The material removal during roughing and finishing is separated from each other. The grinding slide and its guides are not subjected to additional thermal deflections caused by the high-temperature crisps produced during turning, and the slide for roughing and finishing is spatially protected against the influence of grinding powder. The bed meets the requirements for a thermos symmetrical design and allows internal cooling. The advantages of this arrangement from the design, technical and economic points of view are presented.
Reliable measurement of surface roughness (Ra) is extremely important for quality control of production processes. The cost of the equipment and the duration of the measurement process are very high. ...The aim of this work is to develop a device for non-destructive measurement of specific roughness levels on stainless steel using computer vision. The device should be structurally simple, affordable, accurate, and safe for practical use. The purpose of the device is to effectively detect the level of roughness of the treated surface obtained by the water jet cutting process. On the basis of the obtained results, it is possible to adjust the parameters during the cutting process. The principle of operation of the device is based on measuring the intensity of the visible spectrum of the light reflected from the surface of the sample to be measured and correlating these values with the values of the measured roughness. After testing several variants of the device, the so-called vertical measurement variant was developed using the following equipment: violet light LED, optical filter and light splitter, USB 2.0 web camera, Arduino microcontroller, personal computer, and LabView programming interface.
This paper describes a fast Fourier transformation and its application to monitoring tool wear. It describes the transformation of the collected signal during cutting from the time domain to the ...frequency. The introduction describes the discrete Fourier transform, DFT deficiency observed in a large number of samples. Therefore, its use in this case is fast Fourier transform. As an example, an indirect method for monitoring tool wear is shown, based on the measurement values of process variables (acoustic emission) and the relationship between tool wear and these values. Tool wear monitoring is a difficult task because many machining processes are non-linear time-variant systems, which makes them difficult to model and the signals obtained from sensors are dependent on a number of other factors, such as machining conditions.Original Abstract: U radu je opisana brza Fouriova transformacija te njena primjena na pracenje trosenja alata. Opisana je transformacija prikupljenog signala tijekom rezanja iz vremenske domene u frekvencijsku. U uvodu je opisana diskretna Fouriova transformacija, nedostatak DFT se primjecuje kod veceg broja uzoraka. Stoga svoju primjenu u ovim slucajevima nalazi brza Fouriova transformacija. Kao primjer opisana je indirektna metoda za pracenje stanja alata koja se temelji na mjerenju vrijednosti procesnih varijabli (akusticna emisija), na koje utjece vrijednost istrosenja alata. Pracenje trosenja alata je tezak zadatak, jer mnogi obradni procesi su nelinearni vremenski promjenljivi sustavi, te se kao takvi ne mogu modelirati i ti signali dobiveni iz senzora ovise o nizu drugih cimbenika, kao sto su uvjeti strojne obrade.
AlSi9Cu3(Fe) aluminium alloy is one of the most commonly used casting aluminium alloys because their utility is based on good mechanical properties. Production often leads to deviations of maximum ...levels for certain alloying elements, particularly copper. Since mechanical properties of the final products of these alloys strongly depend on the concentration of copper in the alloy, various concentrations of copper were added to the basic alloy whereas the chemical composition was monitored using an optical emission spectrometer, measuring Brinell hardness and doing tensile tests. Moreover, the impacts of copper on oxidizing and corrosion resistance of the experimental alloys were analysed. The alloy with 3 wt. % Cu showed the best results.
When face milling using a toroidal cutter, with a change in the depth of the cut, the entering angle varies as well. An experimental test of the influence of cutting parameters, such as the depth of ...the cut and the feed per tooth on the cutting force components and surface roughness parameters, was conducted. The experimental test was carried out using a DMU 100 monoBLOCK CNC machine with registration of cutting force components and surface roughness parameters Ra, Rz, and RSm. FEM analysis of the face-milling process was also carried out and compared with the experimental results. The average deviation of the FEM values for cutting force components does not exceed 12%. Experimental models were established for each force component. It was shown that the depth of the cut has the strongest influence on each force component. The feed per tooth has a little impact on the cutting force. The obtained model of the feed force component is the most complex, and the model of the F
component is only linear. The influence of the
parameter on the surface roughness parameters is nonlinear and nonmonotonic. In the range of approx.
= 2 mm, there is a maximum surface roughness.
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