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The main problem of grinding of magnetic composites is to combine high efficiency with low grinding temperature. This is difficult due to, among others, different properties of composite components. High temperature is dangerous especially for magnetic component whose integrity may be easily destroyed. To investigate grinding process of magnetic composites the thermal model was developed which enables...
The investigations, which indicate the possibility of controlling the final stresses residing in the surface layer after grinding of a shaft hardened steel being toughened to 56 HRC, have been presented. The results obtained indicate that it is possible to forecast the maximum value of the final stress in the surface layer by an appropriate selection of the machining parameters. The measurement method,...
The durability and performance of bunch-string tools used for cutting hard ceramics were investigated. The strings were designed in the form of a wire or fibre bunch core in a winding coated with an abrasive layer. The windings were made of various materials wound at a different pitch. Two factors turned out to be critical for the durability of such tools: a constant diameter of the string along its...
An algorithm for the identification of the parameters of models, based on the least-squares method and exploiting the properties of the signal wavelet packet analysis, has been proposed. A short introduc-tion to wavelet and wavelet packets’ analysis was presented. It has been shown that the n-th step of the Walsh wavelet packet analysis can yield filtered, smooth forms of the deterministic or randomly...
The paper presents theoretical analysis of dry-ice grains (CO2) behaviour in a high-pressure multiphase liquid jet. The velocities of ice grains at the cryo-sprinkler outlet and in the collision zone were calculated. Their kinetic energy and thermodynamic properties of water-ice jet were also calculated. Experiment methodology concerning two test stands, cryo-sprinkler and dry-ice (CO2) pellets characteristics...
The paper presents the results of the tests on surface microgeometry being formed during internal grinding by means of micro- and monocrystalline CBN and Al2O3 grinding wheels. Surface roughness was characterized by such parameters as: Ra, S, rśr, .a, KPS versus vs, vfa, vw, ae. They describe specific quality of internal grinding surfaces obtained due to work of each of grinding wheels. The detailed...
The genetic algorithm presented in the paper was developed to search for favourable conditions of cleaning by means of the high-pressure abrasive-water jet. Due to application of specific numerical procedures the linear mono-parametric models of the surface machining process were developed. On the basis of process parameters stored in as the input data, the genetic algorithm enabled us to determine...
A system, which improves a decision-making process during grinding operation planning, is described. It should favour the selection of grinding wheel, dressing conditions and grinding conditions. The system was designed as an artificial intelligence hybrid system. Wheel selection is realised by an expert system, while forecasting of grinding results is performed by means of a grinding process model...
The results of comparative studies of the roughness profile of cutting surface of grinding wheel, based on the prophilograms obtained from 2-D and 3-D measurements, were analysed. It was indicated that the cutting surface of the grinding wheel could be considered as a surface of one element of a tribological pair of elements, whose highest peaks are essential in decohesion of the grinded material...
It is possible to reduce considerably manufacturing costs by the application of modern ecological grinding processes. In their paper, the authors present the current state-of-the-art of such processes. They have discussed the following modern and ecological methods of cooling: cooling by means of holes purposely formed in grinding wheels and reducing a flow zone of fluid supply; cooling by the use...
Theoretical analysis of thermodynamical conditions of water-ice jet formation is presented. It was assumed that ice material constitutes the model of grain made of ball-shaped particles of crushed ice H2O of different sizes. The conditions of transport of such “ice abradant” to the cryo-sprinkler and of pre-cooling of high-pressure water jet in the cryogenic technological plant are thoroughly analysed...
The main objective of this investigation is to study the Abrasive Electrodischarge Grinding (AEDG) process performance while machining such advanced materials as polycrystalline diamond (PCD), metal matrix composite Al-SiC, polycrystalline cubic boron nitride (PCBN) and electric conductive ceramics. AEDG machining characteristics obtained with oil and deionized water have been compared. The effects...
In the paper, there have been presented the dependences that describe the intensity of grinding wheels wear which occurs due to elementary processes of grains wear and bond fracture. The interactions between these elements during the grinding process were also analysed. This allowed describing the formulas which render the resulting intensity of grinding wheel wear calculated various grinding conditions...
The character of chipping of the abrasive grain edges is one of the most important factors affecting grinding efficiency. Such a kind of wear is possible when mechanical and thermal tensions exceed an abrasive material resistance. The mechanism of chipping of silicon carbide grains, which was emphasized by the theory of thermal stresses domination, was discussed in the paper. Both temperature and...
Classical processes of manufacturing polycrystalline electro-corundum abradants, using the method of charge melting, have gradually been loosing their industrial significance because of two high energy consumtion, inability to manufacture abrasive grains with the pre-defined stereometry patterns, as well as the inability of the abrasive grains thus manufactured to undergo self-sharpening during grinding...
In the paper, a neural model allowing us to forecast chosen surface layer features of the ground workpiece is described. The model was used for analysing the influence of wheel characteristics and dressing conditions on surface roughness of workpiece and residual stresses. The relationships published in literature were also taken into account. An example of the model application was shown as well.
The paper proposes an approach employing fractal geometry to describe growing martensite phase in an austenitic steel. Inside macroscopic volume (specimen), the distribution of martensite is depicted by measure, and the scaling properties of this measure describe the important, long scale changes of materi-als characteristics. In fact, distribution of martensite relates to two measures. The first...
The paper deals with the stress distribution and stress value in grinding wheels with ceramic binding obtained using the method of optically sensitive surface layer. The tests were conducted with the grinding wheels being loaded both statically and with inertial forces existing during rotation of the grinding wheel. The results obtained were compared to those concerning the dynamic strength of grinding...
Grinding, polishing, honing, lapping and superfinishing are the most common methods of producing fine surface finishes. Fine surface finish and high dimensional accuracy can be obtained in lapping with the use of relatively simple means of pro-ductions. This technology can be used for metallic parts, as well as for non-metallic machine elements, mainly for engineering ceramics which have found use...
The paper presents the topographic model and geometrical parameters of the active surface of grind-ing wheels made of the mixture of two types of abrasive grains and a microsphere. A special filler, called a microsphere by the authors, is a novelty in the structure of such abrasive tools. The aim of this paper was to obtain the basic parameters of microgeometry of such grinding wheels by means of...
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