Papers by Keyword: Grinding

Abstract: The article monitors the effect of length of grinding in the process of homogenization of raw material mixture and soaking on the number of monoclinic phases of alite M1 and M3 in the sample using the Rietveld method. The wet grinding process in the water environment in the planetary mill PULVERISETTE 6 was chosen for the preparation of raw material mixture. Based on previous research in this area, two firing temperatures 1450 and 1550 °C with soaking of 30, 60 and 90 minutes were selected. The results showed the monoclinic phase M1 is more readily formed during coarser grinding, during which large crystals of M1 are formed. On the contrary, the monoclinic phase M3 is formed at a higher firing temperature, at a larger amount nuclei and finer grinding. The results show that the grinding time has an important effect on the rate of formation of monoclinic phases.

Abstract: In this paper, through a series of grinding experiments with different machining parameters on the surface of the workpiece, the surface roughness under different machining parameters are obtained The surface roughness prediction model is constructed by the response surface method. The effects of feed rate, amplitude, and spindle speed on the surface roughness are analyzed. The results show that the surface quality of ultrasonic-assisted grinding is better than that of conventional grinding. Amplitude has the most prominent effect on the improvement of surface quality, followed by the spindle speed. The feed rate has little effect on the surface roughness. The model can predict 93.71% of the experimental results and the prediction error of the model is lower than 5%.

Abstract: Cemented carbide has huge applications in industrial production, but its high mechanical properties also increase the difficulty of processing. In this work, ultrasonic vibration-assisted grinding technology is used for the precision manufacturing of cemented carbide. The influence of the dynamic trajectory of the grains on the material removal process is analyzed. The morphology and roughness of the processed surface are measured and studied. It was observed that in the conventional grinding, the blade pattern is obvious with some defects on the surface. While in the ultrasonic vibration-assisted grinding, the material surface is mainly distributed with pits and small protrusions, and there is no obvious blade pattern. According to the roughness test, the roughness of ultrasonic vibration-assisted grinding is better than that of conventional grinding, and the increase in amplitude has a significant effect on the improvement of roughness. When the amplitude increases from 3μm to 9μm, the surface roughness is improved about 38.1%. The research of ultrasonic vibration-assisted grinding should be of great importance for promote the high-efficiency and high-quality processing and special applications of cemented carbide.

Abstract: One of the critical physical and mechanical properties of metals and alloys is the suitability for abrasive machining. Machining by abrasive tools is the final operation that sets the desired macro-geometry parameters of processed blanks and microgeometry parameters of processed surfaces such as roughness and length of a bearing surface. Abrasive machining determines the most important physical and mechanical parameters of a blank surface layer, i.e. stresses, phase composition, structure. Machinability by abrasive tools depends on the machining performance affected both by the blank material properties and various processing factors. In our previous studies, we proved that during abrasive machining the metal microvolume affected by abrasive grains accumulates energy. This energy is used for metal dispersion and is converted into heat. According to the theoretical studies described herein, one may note the absence of a reliable and scientifically valid method as well as measuring instruments to determine the machinability of metals and alloys by abrasive tools. For this reason, we suggested a method simulating the effect the multiple abrasive grains produce in a grinding wheel, and enabling us to identify machinability of metals and alloys, select the most efficient abrasive materials for machining of the same, and form the basis for development of effective grinding operations.

Abstract: A set of theoretical and experimental studies showing the promising application of devices with the rotating electromagnetic field in the technology of processing sludge wastes of metal production is presented in the paper. Regularities of magneto-vibrational layer formation in those devices and parameters of its energy state control are disclosed. There has also a model of agglomerate destruction in the magneto-vibrational layer been proposed, which establishes a connection of agglomerate particle sizes with the strength of magnetic field induction required for its destruction. The results of studies of the process of ferromagnetic particle grinding are presented, factors affecting the degree of grinding are determined. The possibility of forming an ultradisperse fraction during grinding in the rotating electromagnetic field has been experimentally proved. The effect of porousness on the degree of ferromagnetic particle grinding is shown.

Abstract: X-ray spectroscopic microanalysis was used to determine the concentration of titanium on the surface of the wear spot of a silicon carbide crystal during micro-scratching and the concentration of silicon on the treated surface after grinding by a wheel of silicon carbide. The wear resistance and grinding coefficient of titanium alloys under micro-scratching with single crystals and grinding with wheels made of corundum, silicon carbide, cubic boron nitride and diamond were determined. The morphology of the treated surface and the regularities of changes in the indicators of the grinding process of titanium alloys with circles of various characteristics were studied. The features of the process of grinding titanium alloys using various lubricants and coolants are shown. The influence of the characteristics of the abrasive tool and grinding modes on low-cycle fatigue on the operation of flat and round grinding of samples made of titanium alloys VT9 and VT22 was studied. The influence of abrasive material, grinding speed, feed and sparkout during finishing on low-cycle fatigue was analyzed. Based on the research, recommendations were given for choosing a rational characteristic of the abrasive tool and processing modes.

Abstract: The article deals with the construction of an intensive process of grinding materials using a precast textured wheel and a device for the centrifugal giving of lubricating and cooling liquid (LCL) directly to the local contact zones of the cutting and pressing abrasive grains with the processed material. The design of the tool and an effective method of coolant giving to the cutting zone are described, which provide the required roughness of the treated surface and eliminate structural changes in the surface layer under intensive grinding conditions. An increase in the rate of heat removal from the grinding zone is achieved by using a textured tool design, a device for centrifugal giving of coolant and accelerating the liquid to approximately the cutting speed. A method for constructing an intensive grinding process with a precast textured tool has been developed, the implementation of which can significantly increase the processing efficiency. The results of the research are recommended for grinding steels, cast iron and other metals and alloys that are prone to the formation of cauterization, tensile residual stresses and other thermal defects that occur under the influence of high temperature in the grinding zone.

Abstract: In the science of car repair, the problem of restoring worn-out crankshafts is very relevant. The engineering solutions proposed in the article will provide an increase in the technical and economic indicators of repair: an increase in the quality of coating by a gas-flame method with a finishing non-abrasive antifriction treatment. At the same time, the engineering solution consisting in the formation of one groove on each journal of the crankshaft, brazing of a copper wire, followed by flame spraying of a coating, sealed by a disk, and grinding of the journals (the bearing supports), provides a non-wear effect. So, thanks to the coil of copper wire, the resource of the crankshaft increases and the cost of repaired crankshafts are reduced in comparison with new ones.

Abstract: The article summarizes the results of the of the titanium alloy surface morphology and chemical composition study after grinding with a wheel of cubic boron nitride on a ceramic bond. The titanium alloy was treated using the method of cut-in grinding in the finishing mode using a synthetic water-soluble lubricant-cooling liquid that does not contain mineral oil. The research was carried out using the FEI Versa 3D LoVac electron microscope. Digital photos of the titanium alloy surface at different magnifications are given. Individual objects’ morphology allows us to identify them as wear products of abrasive tools. The chemical composition of the selected objects was studied by local x-ray spectral analysis. CBN crystals are partially or completely pressed into the treated surface and covered with a layer of the treated material. On the surface of CBN crystals, there are chemical elements that are part of the abrasive tool bond.

Abstract: The high adhesive activity of titanium alloys in interaction with abrasive materials is the main cause of poor grinding treatment. The most common abrasive material for grinding titanium alloys is silicon carbide. Silicon carbide wheels operate primarily in self-sharpening mode. Wear of the abrasive tool in the self-sharpening mode occurs as a result of brittle destruction of the fret. The purpose of the study was to determine experimentally the crystalline wear products of an abrasive tool, made of silicon carbide, on the treated surface during grinding of a titanium alloy. Samples of VT9 titanium alloy were processed by flat mortise grinding by a wheel of silicon carbide with the use of VOLTES coolant and the characteristic of the abrasive tool - 64CF80L7V. The treated surface was examined on the electron microscope Versa 3D Dual Beam. The condition of the treated surface testifies to the intensive adhesive interaction of the titanium alloy with the abrasive tool. The thickness of the metal deposits reaches 3 microns. As a result of morphological analysis, objects are identified on the treated surface, the appearance of which allows us to attribute them to crystals. The chemical composition of the selected objects was determined by a microprobe analysis in a microscope camera. On the basis of the conducted researches, a presence on the grinded surface of silicon carbide crystals of various sizes and a ceramic ligament is established.