Study on force and temperature characteristics of micro-grinding nickel-based single-crystal superalloy

Abstract

Aiming at the status of fewer researches on the anisotropy of single-crystal superalloy and micro-grinding temperature field, micro-grinding using the tool of < 1 mm in diameter to remove material is the final procedure of machining micro-parts. This paper firstly analyzes the anisotropy of surface-centered cubic structural material and establishes the theoretical model of elastic modulus and shearing modulus of single-crystal superalloy in the (001), (110) and (111) crystal plane. Afterward, it builds the three-dimensional simulation model of grinding temperature based on the Hill model, adopts any Lagrangian-Euler method to realize the simulation of micro-grinding temperature, gets the distribution of temperature field and changing situation during the micro-grinding through single-factor experiment and simulation analysis, and makes a study on the laws of different grinding depths, feeding rates, grinding velocities, different crystal planes {(001), (110) and (111)} and different crystal orientations in (001) crystal plane that affect the micro-grinding temperature, thus obtaining the crystal orientation which produces low grinding force and temperature. The result indicates that the grinding temperature increases with the increase in spindle speed, feeding rate and grinding depth; the grinding force and temperature are proportional to the elastic modulus and shearing modulus of the single-crystal material; the grinding temperature along (111) crystal plane is the highest, that of the (110) crystal plane is at the middle, and that along (001) is the lowest. When grinding in the (001) crystal plane, the normal grinding force and temperature along [110], [110] , [110] , [110] crystal orientations are the highest, and those along [100], [010], [100] , [010] crystal orientations are the lowest. And along with the aggravating of wear of abrasives on the grinding tool, the normal grinding force, tangential grinding force and grinding temperature all increase and the wear state of grinding tool can be judged online according to the signal of grinding force and temperature. These results provide an important evidence to do further research on the surface integrity of grinding single-crystal superalloy.

Study on theoretical model of roughness and wear of the microgrinding tool in microgrinding nickel-based single crystal superalloy

“…This is mainly because when the speed is low, the surface vibration traces appear, as shown in Fig. 6; when the spindle speed is high, the grinding temperature is high [27], the deformation on the machined surface increases, which affects the surface quality.…”

“…There are several reasons. The grinding force, grinding temperature and cutting thickness of a single abrasive increase with the increasing of feeding rate [27]. The material is not removed in time, and the large deformation leads to bad surface roughness.…”

“…Chen et al [30] analyzed the primary wear forms of porous composite-boned CBN wheel included abrasive abrasion wear, abrasive and bond fracture, and adhesion wear. With the further abrasion of abrasives on the surface of the grinding tool, the grinding force of workpiece material on the abrasives increases sharply, the grinding temperature increases [27], and the rate of abrasive's wear accelerates. The diameter of the grinding tool changes rapidly, the wear rate of the grinding tool increases gradually, the wear of the grinding tool is serious, many of the abrasives fall off, and the grinding tool tends to be scrapped gradually, as shown in Fig.…”

Evaluation of the grinding process utilizing an auxiliary compressed air jet on cleaning the grinding wheel surface

“…Grinding wheel lifespan is reduced when sharpening is increased, especially in the case of super-abrasive grinding wheels. 11,12 The continual dressing could be a method to reduce the wheel loading phenomenon and keep high-porosity grains on the surface of the wheel. However, this will result in a significant increase in wheel prices.…”