Papers by Keyword: Specific Grinding Energy

Abstract: Based on geometry model of single abrasive particle, comparing abrasive geometries of different materials displayed in SEM images, it is proposed that abrasive geometry is similar to inverted cone with vertex radius in sphere. Based on abrasives with inverted cone geometry, through introducing sliding ratio, mathematical models of cutting force and specific grinding energy of single abrasive have been established to study about cutting force in meshing line of single abrasive; in accordance with specific grinding energy of single abrasive, combined with internal meshing principle, the relationship among specific grinding energy, engagement, and meshing line length l have been studied. Through simulation analysis, it is shown that the unit normal force of single abrasive in whole meshing line gradually increases from tooth top to pitch line and tooth root; the greater the value of l from pitch line to tooth top, the more the specific grinding energy accordingly; however the greater the value of l from pitch line to tooth root, the smaller the specific grinding energy therewith; the greater the engagement, the smaller the specific grinding energy which tends to stable with changing of l.

Abstract: The high hardness of brittle materials always make it hard to machine with traditional grinding wheels. Conventionally a diamond grinding wheels was used to improve the poor processing capability. Usually the specific grinding energy had been used as an indicator of machinability. According to its definition, the specific grinding energy increases with the active contact area of the grinding wheel decreases. In other words, reducing the surface contact area of the grinding wheel can enhance the specific grinding energy effectively. Conditioning grooves on grinding wheels not only enhance the specific grinding energy, but also achieve the effect of reducing the heat dissipated during the grinding processes. With the proper selection parameters, the high cost of diamond grinding wheel may be replaced by less expensive conventional green carbon and aluminum oxide wheel. In this studies, the relationship between the surface topography of grinding wheels and the grinding capability of brittle materials was investigated. The results show that, the traditional grinding wheel dressing properly while the depth of cut less than 20μm with the rhombic pattern and the depth of cut more than 20μm with the groove-like pattern can grind the brittle materials as good as using diamond wheel.

Abstract: In the present work, ultrasonic assisted grinding (UAG) and conventional grinding (CG, without ultrasonic) tests of Carbon fiber reinforced silicon carbide matrix (C/SiC) composites were conducted. In addition, analysis was done by comparing the machining quality, grinding force, and specific grinding energy between the two processes. The results showed that material removal mode of carbon fiber both in CG and UAG were brittle fracture, and fracture size had no obvious difference. Compared with CG, brittle fracture area of SiC increased during UAG. In comparison with CG, the normal grinding force and tangential grinding force for UAG were reduced maximally by 45%, 39% respectively of those for CG. Accordingly, specific grinding energy was also reduced by UAG. Therefore, UAG can improve the grinding performance of C/SiC composites significantly.

Abstract: In this paper, plunge grinding experiment was conducted on 20CrMnTi with monolayer brazed cubic boron nitride (CBN) wheel. Surface integrity was evaluated through morphology observing and roughness testing. It is found that surface roughness Ra is lower than 0.8μm. Grinding forces were measured and the effects of process parameters (i.e. workpiece speed and depth of cut) on grinding forces were studied. The changing regulation of specific grinding energy with the increase of equivalent chip thickness was revealed. The result shows that both grinding force and specific energy are lower comparing with white fused alumina (WA) wheels. In general, monolayer brazed CBN wheels perform better in grinding of 20CrMnTi than WA wheels.

Abstract: For hard, brittle and difficult-to-cut materials, the technology heating auxiliary grinding has a significant role in improving productivity and reducing costs. Using different thermal loads and different ways of cooling to load granite,we carried out surface grinding experiments. We tested and analyzed variation of the grinding force and specific grinding energy. The results showed that strengthening the thermal load continuously, the grinding force and specific grinding energy reduce. This phenomenon significantly improves grinding efficiency and reduces the wear of wheel. Studies have shown that the auxiliary heating has an important contribution to enhance the production capacity of the stone processing.

Abstract: Metal-bonded cBN wheels with regular pores were fabricated using Cu-Sn-Ti alloy, cBN abrasive grains and alumina (Al2O3) bubble particles. Dressing experiments were carried out through rotary dressing method. Subsequently, grinding experiments were conducted on nickel-based superalloy GH4169. Comparative grinding performance was evaluated with vitrified cBN wheels in terms of grinding force and specific grinding energy. The results reveal that the pores in the working layer of the cBN wheels are exposed after rotary dressing. Compared to vitrified cBN wheels, grinding forces and specific grinding energy of the newly developed cBN wheels with regular pores are smaller.

Abstract: An investigation was undertaken to explore the grinding energy and removal mechanisms in grinding zirconia by using brazed diamond wheels. The grinding forces were measured and the morphological features of ground workpiece surfaces were examined. The results indicate that material removal mechanisms are dominated by the combined removal modes of brittle and ductile. The prevailing removal mechanism for the ground surface of zirconia changes from brittle to ductile when the maximum chip thickness change from large to small.

Abstract: An investigation was undertaken to explore the specific energy and material removal mechanisms involved in the grinding of cemented carbide with vacuum brazing diamond wheels. A mathematical model, relating to the grinding parameters such as wheel velocity, workpiece feedrate and depth of cut, was proposed to predict specific grinding energy, and was verified by experimental data. This verification came as a result of surface grinding two typical cemented carbides (YG8 and YG30) with a vacuum brazing diamond wheel under various grinding conditions. The earlier model’s prediction shows a direct correlation with the experimental results. Good relationships between the consumed power per unit width with the plowed face areas generated by all cutting points per unit width were obtained. Microscopic examination of the ground surfaces and the grinding detritus by a digital and video microscope system also revealed that material removal occurred mainly by flow-type chip formation (plastic flow) while grinding YG8 and by blocky fracture particles formation (brittle fracture) while grinding YT30.

Abstract: Focusing on the characteristic of hard-to-grinding for viscous materials, such as titanium alloy, systemic process experiments were done about grinding viscous materials, such as TC4 titanium alloy, under the high efficiency deep grinding (HEDG). Based on the analysis to the changing and characteristic of unit area grinding force F' with maximum undeformed chip thickness hmax and equivlent cutting thickness aeq , this paper discussed the changing of its material removal mode and analyzed the changing and characteristic of grinding force ratio N, specific grinding energy es with corresponding parameters further. Then, it was analyzed about the consumption of grinding power on the process of HEDG for TC4 titanium alloy. The experiment results reveal that application of HEDG can improve machining efficiency of grinding viscous materials.

Abstract: Grinding experiments for quenched high-speed tool steel by resin bonded CBN (cubic boron nitride) wheel were conducted with a surface grinder. The grinding forces were measured under different grinding parameters. The effects of grinding parameters on grinding forces and grinding force ratio are discussed. Specific grinding energy and heat flux over the grinding zone are computed according to grinding parameters and grinding forces. The effects of grinding parameters on specific grinding energy and heat flux are investigated.