Papers by Keyword: Cylindrical Grinding

Abstract: The joint research of scientists of two countries deals with cylindrical and surface grinding with abrasive wheels of heat-resistant steel Inconel 625 (KhN77TYu GOST 5632 – 72 Russian Federation standard), (analogues include Hastalloy, N07080, Alloy 80A, Nimonic 80A, 2.4952 ASTM B637/ASME SB637, UNS N07080). The article shows the results of studies of the features of high-temperature steel during grinding with a fastened abrasive. The results of experiments are given to determine the optimal characteristics of grinding wheels, grinding modes, cooling-lubricant fluids. Experimental data about geometric accuracy, surface roughness, resistance of wheels are demonstrated as well. The ways to prevent from defects during cylindrical and surface grinding of high-strength steel are proposed. The recommendations to increase the tool resistance and output of the process are given.

Abstract: Grinding is a main method of silicon nitride ceramic in finish machining stage. The technical parameters had an important influence on the surface quality of silicon nitride ceramic. The silicon nitride ceramic spindle was ground by the high-speed cylindrical grinder MGKS1432-H. The relations between different speed parameters and surface roughness were researched. The cylindrical and internal high speed grinding experiments of silicon nitride ceramics spindle were carried out. The S-4800 scanning electron microscope was used to explore the roughness change rule of the grinded surface under the condition of only changed grinding wheel’s velocity. In the process of cylindrical and internal grinding on silicon nitride ceramic spindle, the roughness tended to decrease with the linear velocity increasing, and increased with the radial feed speed increasing and decreased with the wheel shaft’s oscillation speed increasing. The result indicated that the linear velocity of grinding wheel influenced the sample’s roughness most. The effect of radial feed speed on the roughness is next only to the effect from linear velocity. The effect of shaft’s oscillation speed on the roughness is the lowest of the three factors. In the process of internal grinding, with the linear velocity increasing, the ceramic material transformed from brittle rupture to plastic deformation and the roughness appeared one peak. These results were very helpful to optimize the grinding parameters and improve grinding efficiency.

Abstract: Structuring of the grinding wheels is a promising method to reduce the forces involved in grinding, especially during dry grinding. In this paper, one of the methods of grinding wheel structuring is presented. The structuring process was modeled to find the corresponding dressing parameters for the desired structure dimensions. The cylindrical grinding operation with the structured wheels was simulated to produce a spiral free ground surface. Afterwards, the dry grinding experiments with the structured and non-structured wheels were carried out to evaluate the efficiency of the structured wheels. The results revealed that the grinding forces can be reduced by more than 50% when the grinding wheels are structured, while the surface roughness values increase by 80%.

Abstract: This paper presents an investigation of possibilities of using regression analysis and genetic algorithms in modelling the cutting force values in cylindrical grinding. The process included measurement of cutting forces during cylindrical grinding and later calculating their values using abovementioned techniques. It was concluded that both techniques can be used for cutting forces modelling with genetic algorithms having a slight advantage.

Abstract: While grinding with CNC cylindrical grinding machines, there are many factors that determine the precision and accuracy of the finished product. These may include dimensional accuracy, surface roughness, circularity (roundness), cylindricity, etc. But all these factors pertain to the work. The condition of the tool, in this case, the cutting edges of the grinding wheel, also greatly influence the profile and precision of the work. So, in order to maintain the precision of the work, there is a need to repeatedly and regularly maintain the cutting edges in a good cutting condition, by the process of dressing. In other words, when the swarf gets adhered to the grinding wheel, the abrasive particles can no longer perform machining with the same efficiency, due to increase in contact surface area between the abrasive particles and the work. This dissertation describes a technique that can be adopted to continuously monitor the grinding forces generated during the grinding operation, by using an in-process 2-dimensional piezoelectric force sensor, which can simultaneously measure the force and break it down into its two force components. The force sensor not only calculates the force generated, but also quantifies the force variation. By analyzing the variation in the radial and tangential force components individually, and by conducting Fourier analysis on the observed data, it is found that deterioration of the grinding wheel and the dress pattern can be continuously monitored and controlled.

Abstract: The present research work involves investigating the cylindrical grinding process parameters of Al/SiC metal matrix composites during machining. The effect of grinding process parameters on grinding force, surface roughness and grinding temperature were investigated experimentally using L₂₇ orthogonal array. Grinding process was carried out using different combination of wheel velocity, workpiece velocity, feed rate and depth of cut. The significant grinding process parameters have been determined by using ANOVA. The grey grades identify the optimum level grinding process parameters. From the grey relational grade, low wheel velocity, medium workpiece velocity, medium feed rate and medium depth of cut gives the best results.

Abstract: In order to decrease the negative environmental impacts of the cutting fluids (for example, disposal of grinding sludge) and also to reduce the manufacturing costs and the required space for the machines the dry grinding can be a conceivable alternative for the conventional grinding processes. Nevertheless, dry grinding has not been widely introduced into industry because of the high temperature generated in the grinding zone and difficulties of heat transfer without coolants. Selection of the proper grinding wheel bonds, grit sizes and concentration has significant effect on the grinding performance and the generated heat in the contact zone. This paper addresses the effects of the grinding wheel bond and the concentration on the dry grinding process efficiency through comparing the results of the carried out experiments with three resin bonded cBN-cup-wheels, each consisting different bond components. For this purpose, surface roughness and thermal damages during dry and wet grinding (utilizing grinding oil) by three different resin bonds were measured. The results show almost identical surface roughness values for dry and wet grinding. Furthermore, using the resin-kryolith-graphite bonded wheel leads to a reduction in thermal damages on the workpiece. Through different experiments, it was shown that the different bonds, used in this study, have significant influence on the chip loading of the grinding wheels. This is contributed to the different chip formation mechanisms and induced grinding temperatures when grinding by the different wheel bonds.

Abstract: In order to reduce the roundness error of cylindrical grinding of shaft parts for 20CrMnTi alloy steel, the related experiments of high-speed cylindrical grinding are carried out and the influence of grinding parameters on roundness is analyzed. Based on the analysis of experimental data the conclusions are as follows: The influence of grinding wheel speed on work-piece roundness is not apparent, but the influence of work-piece speed and grinding depth on roundness is very significant. Based on high-speed grinding experiments the prediction model of cylindrical grinding for 20CrMnTi alloy steel is established by using of regression analysis method of least square. Based on the analysis of the roundness prediction model of cylindrical grinding the conclusions are as follows: The roundness error of cylindrical grinding parts will become lager with the increase of work-piece speed, grinding depth and grinding wheel speed.

Abstract: In cylindrical grinding, a sizing device is generally used to obtain the required dimension. However, the dimensional error can be caused by the thermal deformation of the workpiece even if grinding machine is controlled with the sizing device. To solve this problem, it is necessary to develop the grinding system that can consider the thermal deformation of the workpiece during grinding process. In this study, an advanced grinding system was developed, which can predict the net stock removal of ground workpiece immediately. The grinding experiment is carried out to verify the developed system.

Abstract: This paper is focused on the application of acoustic emission (AE) based monitoring systems to grinding processes. To develop the AE signal model for the process monitoring, a comparison between the AE and power signals is presented. The AE model is developed according to a traditional grinding force model. Based on the developed model, experiment indicates the AE signal is similar to the power of spindle and verifies the proposed AE model can be used to predict the AE root meam square (RMS) signal for monitoring the grinding process.