Study on Chip Formation in Grinding of Nickel-Based Polycrystalline Superalloy GH4169

Based on the variation of the actual cutting depth during the grinding process, a 3D finite element (FE) simulation model for grinding nickel-based superalloy GH4169 with single abrasive was initially constructed. Then the morphological evolution of the grinding chips during the grinding process was studied. In addition, the effect of the single abrasive cutting depth and the grinding speed on chip morphology and segmentation frequency was investigated. Finally, experimental results with the same test parameters verify the finite element simulation results. The results showed that in the experimental grinding speed range, the sawtooth lamellar chip with the free surface being serrated and the contact surface being smooth due to the extrusion of the abrasive is easy to produce when grinding nickel-based superalloy GH4169. As the grinding speed increases, the chip morphology changes from a unitary lamellar chip to a continuous serrated chip, developing into a continuous ribbon chip. The chip segmentation frequency is mainly determined by grinding depth and grinding speed. To be specific, the smaller the grinding depth and the greater the grinding speed, the greater the chip formation frequency.

Prediction of Abrasive Belt Wear Based on BP Neural Network

Abrasive belt grinding is the key technology in high-end precision manufacturing field, but the working condition of abrasive particles on the surface of the belt will directly affect the quality and efficiency during processing. Aiming at the problem of the inability to monitor the wearing status of abrasive belt in real-time during the grinding process, and the challenge of time-consuming control while shutdown for detection, this paper proposes a method for predicating the wear of abrasive belt while the grinding process based on back-propagation (BP) neural network. First, experiments are carried out based on ultra-depth-of-field detection technology, and different parameter combinations are used to measure the degree of abrasive belt wear. Then the effects of different grinding speeds, different contact pressures, and different work piece materials on the abrasive belt wear rate are obtained. It can be concluded that the abrasive belt wear rate gradually increases as the grinding speed of the abrasive belt increases. With the increase of steel grade, the hardness of the steel structure increases, which intensifies the abrasive belt wear. As the contact pressure increases, the pressure on a single abrasive particle increases, which ultimately leads to increased wear. With the increase of contact pressure, the increase of the wear rate of materials with higher hardness is greater. By utilizing the artificial intelligence BP neural network method, 18 sets of experiment data are used for training BP neural network while 9 sets of data are used for verification, and the nonlinear mapping relationship between various process parameter combinations such as grinding speed, contact pressure, workpiece material, and wear rate is established to predict the wear degree of abrasive belt. Finally, the results of verification by examples show that the method proposed in this paper can fulfill the purpose of quickly and accurately predicting the degree of abrasive belt wear, which can be used for guiding the manufacturing processing, and greatly improving the processing efficiency.

Selection of parameters during shredding of corn stalks as an additive to the polymer

This paper presents the results of research on the process of grinding dried corn stalks to use them as polylactide filler. Shredding was carried out on a laboratory shredder with the use of a design variant based on discs with cylindrical holes. By selecting the design variant, the appropriate grinding speed and the material pressure on the shredder discs, the most favourable parameters in terms of the quality of the shredded product and low energy consumption were selected. The research was conducted to reduce the energy demand during the shredding process and to obtain the shredded material suitable for further processing steps.

The Story of a Re-Operating Windmill

Research on the history of the development of grain milling structures is a priority topic of the Department of Technical Sciences of the Transylvanian Museum Association. Quite a few publications and study volumes contain the results of the research. The present dissertation presents another grinding structure, the windmill, its reconstruction, creating a connection between the theoretical foundations and the practical implementation. Although it was built as a museum and tourist object, it is also a significant work from the point of view of technical history. The Felsőszentiván windmill is powered by a 14-meter-diameter windmill. The mill has a two-stage accelerator gear that increases the low, non-grinding speed of the wind turbine for the rotation typical of grindstone mills. The upper stones of a pair of grindstones rest on a vertical axis, and by raising this the gap between the stones can be adjusted. This determines the particle size of the grind. The windmill consists of three functional parts: a windmill, an accelerator gear and a grain mill made up of a pair of grindstones.

Machinability of enamel under grinding process using diamond dental burrs

Enamel grinding is a critical dental surgery process. However, tooth damage during the process remains a significant problem. Grinding forces, burr wear, and surface quality were characterised in relation to grinding speed, enamel orientation, grinding depth, and burr grit grain size. Results indicated that enamel rod orientation, grinding depth, and grinding speed critically affected enamel grinding. Occlusal surface grinding resulted in significantly higher normal forces, surface roughness, and marginally greater tangential forces than axial surface grinding. Damage to enamel machined surfaces indicated the significant impact of diamond grit size and rod orientation. Burr wear was primarily diamond grit peeling off and breakage. Surface roughness of axial and occlusal sections was largely influenced by grinding speed and diamond grit size. Improving the surface quality of machined enamel surfaces could be realised using fine burrs, reducing the grinding speed and grinding depth, and adjusting the feed direction vertical to the rod orientation. Enamel surface quality and roughness could be improved by reducing brittle failure and circular runout during the grinding process, respectively.

The Grey Theory Combining the Taguchi Method for the Best Parameters: A Case Study of Polishing M300 Steel

M300 steel, as high-chromium alloy steel with strong wear resistance and corrosion resistance, is widely used in the manufacture of complex profile molds and aerospace military equipment such as missile parts. However, there are still some problems such as the contradiction between productivity and surface quality in the polishing process for M300 steel. Therefore, in order to solve these problems, surface polishing experiments on M300 steel, single-factor and orthogonal experiments, and parameters’ optimization were studied. In this paper, orthogonal experiments are conducted for four selected machining parameters: grain size (A), grinding speed (B), cutting depth (C), and feed rate (D) on a grinding machine. The experiment and parameters’ optimization of the ball type abrasive tool polishing M300 were investigated by a five-axis machining center, electronic analytical balance, and three-dimensional surface topographer, and the optimal process parameters and preferred intervals were optimized. The optimal parametric condition obtained for simultaneous minimization of surface roughness (Ra) and maximization of material removal rate (MRR) is as follows: grain size=#320, grinding speed=4500 r/min, cutting depth=0.4 mm, and feed rate=80 mm/s. The above parametric combination has been validated by confirmatory tests.

Residual Stresses Distributions in Grinding of 3J33 Maraging Steel with Miniature Electroplated CBN Wheel

It is well known that the residual stresses on the ground surface and the subsurface can influence the service quality of a component, such as fatigue life, tribological properties, and distortion. In this paper, an experimental investigation was conducted to determine the effects of grinding force, temperature and grinding conditions, such as grinding speed, workpiece speed and grinding depth, on the surface and in-depth residual stresses distributions induced by grinding of 3J33 maraging steel with the miniature electroplated CBN Wheels. The results show that a ‘hook’ shaped residual stress profile is generated with the maximum compressive stresses occur at the depth of 3-14 ?m below the ground surface. There is a good correlation between residual stress and cutting force, but the trend related to grinding temperature is not obvious. The main grinding parameters affecting the residual stresses distributions is grinding speed, while the workpiece speed and grinding depth have the least effect.