Influence of Wear Volume on Surface Quality in Grinding Process Based on Wear Prediction Model

In the grinding process, the workpiece would not only be cut by abrasive grains, but also have adhesive wear caused by high temperature and heavy load, which makes the surface quality of the workpiece worse. In this paper, a wear test method considering speed, force, wear coefficient, temperature and hardness was proposed. A new wear prediction physical model was established based on finite element method and numerical simulation technology. The wear test was carried out on a grinding machine. The comprehensive research on the relationship between force, temperature, surface morphology and wear volume of grinding process was studied. The relationship between workpiece speed, grinding depth, cooling lubrication conditions and wear volume of grinding process was studied. The results show that the wear model can achieve numerical prediction and trend prediction of grinding temperature, surface profile and wear volume, the relative errors between the theoretical and actual values of wear and grinding temperature are 9.84% and 2.07% respectively. This study provides a support for wear prediction and surface quality control of grinding process from the perspective of temperature and micro material removal form.

Electrodischarge Methods of Shaping the Cutting Ability of Superhard Grinding Wheels

In the paper, the influence of the electrodischarge dressing methods of superhard grinding wheels on shaping their cutting ability are presented. The results of research concerning the influence of dressing conditions using a stationary electrode, rotating electrode and segmental tool electrode on shaping the cutting ability of the superhard grinding wheels are reported. The cutting ability of superhard grinding wheels is assessed using an external tester made of titanium alloy Ti-6Al-4V (with a thermocouple) to determine the grinding temperature and the relative volumetric grinding efficiency of the tool. The results of the research reveal the diversified usefulness of the analyzed methods. At the end of the article application conclusions concerning the adaptation of developed methods of electrodischarge dressing in the industry are formulated.

Grinding Force and Heat of Titanium Alloy Abrasive Belt and Its Effect on Surface Integrity

Key rotating parts such as integral blisks and blades of aero-engines are widely made of titanium alloys. Abrasive belt grinding is one of the effective methods to improve the surface integrity. However, the grinding process produces greater grinding force and higher Grinding temperature,which have an impact on surface quality. At present, the force-heat coupling relationship in the grinding process and its influence on surface quality have not been explored. In this paper, a titanium alloy belt experiment is carried out to detect the force and temperature in the grinding process, this paper explores the influence of the grinding process parameters on the grinding force and temperature, and analyzes the influence on surface integrity of the force and temperature in the grinding process. The results show that the decrease of the belt linear speed, the increase of the feed speed and the grinding depth leads to the increase of the grinding force, the decrease of the feed speed, the increase of the belt linear speed and the grinding depth cause the temperature to rise. The effect of grinding depth on grinding force and grinding temperature is the most significant. And High grinding force and grinding temperature will cause the surface quality to deteriorate and even more serious defects. However, when the maximum temperature of the grinding temperature field reaches above 120°C, the surface roughness of the workpiece decreases from 1.596μm to 1.093μm, and the height of the surface undulation is reduced from 32μm to 19μm. This paper provides a reference for improving the surface integrity of the grinding process.

Hardness Prediction of Grind-Hardening Layer Based on Integrated Approach of Finite Element and Cellular Automata

As an emerging composite processing technology, the grind-hardening process implements efficient removal on workpiece materials and surface strengthening by the effective utilization of grinding heat. The strengthening effect of grind-hardening on a workpiece surface is principally achieved by a hardened layer, which is chiefly composed of martensite. As a primary parameter to evaluate the strengthening effect, the hardness of the hardened layer mostly depends on the surface microstructure of the workpiece. On this basis, this paper integrated the finite element (FE) and cellular automata (CA) approach to explore the distribution and variation of the grinding temperature of the workpiece surface in a grind-hardening process. Moreover, the simulation of the transformation process of “initial microstructure–austenite–martensite” for the workpiece helps determine the martensite fraction and then predict the hardness of the hardened layer with different grinding parameters. Finally, the effectiveness of the hardness prediction is confirmed by the grind-hardening experiment. Both the theoretical analysis and experiment results show that the variation in the grinding temperature will cause the formation to a certain depth of a hardened layer on the workpiece surface in the grind-hardening process. Actually, the martensite fraction determines the hardness of the hardened layer. As the grinding depth and feeding speed increase, the martensite fraction grows, which results in an increase in its hardness value.

AUTOMATIC CONTROL OF TEMPERATURE AND POWER CONDITIONS DURING ROUGH GRINDING OF SLABS

The production of high-quality rolled products (slabs), the formation of its surface phase-structural composition, texture, stress state during rough grinding depends on the temperature in the area of contact between the wheel and the slab. During processing, due to geometric errors of the rolled surface, as well as due to local changes in hardness, periodic fluctuations of the instantaneous depth of cut occur, which can be determined indirectly by controlling one of the technological parameters, for example, the power spent on grinding, with subsequent recalculation it to online temperature values. The grinding temperature is described as a control object in the form of an aperiodic link. Computer simulation has confirmed the efficiency of the system for maintaining the specified temperature of slab grinding under various operating conditions that simulate the situations of real production.

Study on the Effect of Grinding Pressure on Material Removal Behavior Performed on a Self-Designed Passive Grinding Simulator

Passive grinding is a new rail grinding strategy. In this work, the influence of grinding pressure on the removal behaviors of rail material in passive grinding was investigated by using a self-designed passive grinding simulator. Meanwhile, the surface morphology of the rail and grinding wheel were observed, and the grinding force and temperature were measured during the experiment. Results show that the increase of grinding pressure leads to the rise of rail removal rate, i.e., grinding efficiency, surface roughness, residual stress, grinding force and grinding temperature. Inversely, the enhancement of grinding pressure and grinding force will reduce the grinding ratio, which indicates that service life of grinding wheel decreases. The debris presents dissimilar morphology under different grinding pressure, which reflects the distinction in grinding process. Therefore, for rail passive grinding, the appropriate grinding pressure should be selected to balance the grinding quality and the use of grinding wheel.

Systematic Monitoring and Evaluating the Wear of Alumina Wheel When Grinding the Workpiece of Cr12

The performance of the grinding wheel demonstrably affects the machining efficiency and the quality of the workpiece. Therefore, it is essential to evaluate the wear of the wheel and then operate the dressing or replacement in time. The wear procession of the wheel was monitored and evaluated systematically in this paper. A surface grinding experiment was performed by using an alumina wheel to grind the workpiece made of Cr12. The grinding force and the grinding temperature were monitored and measured while the wheel grinds the workpiece. The surface topography of the wheel was also being observed. The distribution of the gray value of pixels in the image of the wheel surface was analyzed by the method of the histogram. Processing of the binary image of the wheel was performed after determining the gray threshold of the gray value. Then, the blockading and the wearing area on the grinding wheel were calculated. Moreover, the relation of the projection area of a single abrasive derived from theory and derived by image recognition was studied. The results of the grinding experiment show that wheel performance degradation occurs when the material removal volume reaches 210 mm3/mm. At this time, the ratio of blockage area on the grinding wheel reaches 13.4%. The percentage of the wearing area is 9.5%. The method of image recognition combined with grinding temperature is workable to realize monitoring and evaluating the wear of wheels on site without unloading them.

Experimental Evaluation on the Effect of Nanofluids Physical Properties With Different Concentrations on Grinding Temperature

This chapter is proposed to solve the insufficient MQL cooling and heat transfer capability based on the heat transfer enhancement theory of solid. Adding nanoparticles into the base fluid can significantly elevate heat conductivity coefficient of the base fluid and enhance convective heat transfer capability of the grinding area. Researchers have carried out numerous experimental studies on nanofluids with different concentrations. However, the scientific nature of MQL cooling has not been explained. Degradable, nontoxic, low-carbon, and environmentally friendly green grinding fluid, palm oil taken as the base fluid, grinding force, grinding temperature and proportionality coefficient of energy transferred to workpiece of nanofluids with different volume fractions, are investigated in this chapter. Based on the analysis of the influence of physical characteristics of nanofluids on experimental results, cooling and heat transfer mechanism of NMQL grinding is studied. The experimental study can provide a certain technical guidance for industrial machining.