Simulation Research In Three Dimensional Spiral Ultrasonic Vibration Assisted Grinding Of Hard And Brittle Materials By Using SPH Method

With the development of science and technology, the demand of hard and brittlematerials and advanced materials is increasing significantly. However, these materials arevery hard and brittle. In machining process, there may form surface/sub-surface microcrack,which may affect the performance of the workpiece. Grinding is one of the most widelyused precision processing technology, in order to improve processing efficiency and theworkpiece surface quality, grinding is usually used in the final machining process.Conventional grinding process may generate a lot of grinding heat and grinding force,which may reduce the using performance and reduce the wheel life. It’s confirmed byrelevant researches that, three dimensional spiral ultrasonic vibration assisted grinding(3DSUAG) method is an effective approach to solve these problems. However, the materialremoval mechanism in3DSUAG is still unclear. This research based on kinematics, metalcutting theory, knowledge of material removal mechanism, and digital computation, withthe combination of numerical simulation and theoretic analysis, the mechanism of3DSUAG method was investigated. This research focus on the analysis of cutting path, chipformation mechanism, and grinding forces, material removal mechanism were clarified.This research provides theoretical foundation and technical support to the wide applicationof3DSUAG technology in the field of ultra-precision machining of brittle materials. Themain research contents are listed as follows:1. Based on the general kinematic theory between the abrasive grain and theworkpiece, we built four types of single abrasive grain cutting processes, i.e.,3DSUAG,axial ultrasonic assisted grinding (AUAG), vertical ultrasonic assisted grinding (VUAG),and conventional grinding (CG). Then the variation of relative motion, velocity andaccelerate between the abrasive grain and the workpiece were analyzed to reveal themechanism of improving surface quality and reducing the grinding forces in3DSUAG.2. Discussed the modeling method in3DSUAG based on Smoothed ParticleHydrodynamics method (SPH). Numerical simulation by using SPH method of singleabrasive grain grinding process was made by using ANSYS/LS-DYNA. By comparing thesimulation results of ultrasonic assisted grinding AISI4340steel between FEM and SPH methods, we proved the advantages of SPH method in single abrasive grain ultrasonicassisted grinding simulation.3. Single abrasive grain grinding process in CG, AUAG, VUAG and3DSUAG weresimulated respectively in grinding brittle material and plastic material by using SPHmethod. Chip morphology, material removal mechanisms, and distribution of stress andstrain were analyzed after the simulation to reveal the material removal mechanism in3DSUAG.4. Build the force formula of a single abrasive grain in CG, AUAG, VUAG and3DSUAG. Analyzed the force-reducing mechanism in AUAG, VUAG and3DSUAGprocess. Then we simulated the single abrasive grain grinding SiC ceramic process and gotthe forces of the single abrasive grain in different grinding Pattern: in AUAG, VUAG and3DSUAG, the grain forces is less than in CG. The forces of single abrasive grain in3DSUAG are between the forces in AUAG and VUAG. In3DSUAG the average axial forceis not zero.