Ke Hua Zhang

Experimental Investigations into Abrasive Flow Machining of Helical Gear

Abstract. Abrasive flow machining (AFM) is an effective method that uses the flow of a pressurized abrasive media for removing workpiece material. It is used to deburring, polishing or radiusing, etc. In this paper, the effect that AFM process on the surface of the helical gear is investigated. Then, the distribution of the velocities, shear rates and shear forces of the abrasive flow on the helical gear surface is obtained by CFD module of the COMSOL Multiphysics software. The simulation results show that the abrasive grains near the addendum, tooth surface and tooth root can be subjected to corresponding shear stress. Experimental results indicated that the surface roughness Ra of the left tooth surface, right tooth surface and addendum before processing 1.429um, 1.108um and 2.732um dropped after processing 0.228um, 0.216um and 1.754um. All burrs at the intersection between tooth surface and end surface has been cleared, the surface quality of the helical gear has been improved. Therefore, AFM method can improve the surface quality of the helical gear effectively.

Study on the Effect of Ultrasonic Surface Rolling Processing Parameters on the Surface Roughness of Q345 Hydraulic Prop

The surface roughness of the hydraulic prop had an important effect on the wear resistance, fatigue strength and property of fit. The ultrasonic surface rolling extrusion (USRE) processing experiment was employed to improve the surface roughness of the hydraulic prop, some machine parameters such as the tools transfer magnitude, feed were studied in detail, the contact style roughness tester( Mahr S2) was used to test the surface roughness of the workpiece. The experiment results showed that the USRE could improve the surface roughness evidently, the Ra value from 0.976μm reduce to 0.105 μm by one-hit machining. The feed was linear with the surface roughness, and when the tools’ amplitude was 6.5~8.5, there were a better surface roughness Ra 0.090μm. USRE processing the surface time and again could improve the surface state.

Study on the Abrasive Effecting Factors of the Removal Rate during Dual-Lapping Sapphire Wafer

Dual-lapping was a process to planarize the surface of the sapphire wafer, the nature of surface&subsurface damage and the surface uniformity was depended on the material removal mode and materials removal ratio. Material removal mode was studied in this paper, and the model of material removal was set up too. The SEM was used to scan the processed sapphire surface and the different removal style (two body and three body) were discovered. This research provided valuable insights into the material removal ratio and the dependence of lapping-induced damage on dual-lapping conditions, the asymmetry of abrasive granularity brought on the different materials removal mode and the surface asymmetry. The model was set up to qualitative analysis the material removal ratio in dual-lapping of sapphire, obtain the reasonable MMR and optimize the surface quality and the planarization result.

The Characterization and Experiment Research of Ultrasonic Rolling Machining for Column Surface

The machining method and characteristic of the ultrasonic extrusion-rolling machining was introduced in the paper. According to the machining characteristic, the kinematic analysis of the machining mechanism and surface anamorphic was analyzed too. And then the correlative theory of tribology was adopted to discuss the relation between surface anamorphic quantity and the technological parameter. The theory foundation was afforded for the choice of technological parameter.

Study on the Mechanical Properties of Sapphire by Numerical Simulation and Nanoindentation Technology

This paper presents a finite element (FE) modeling of the nanoindentation test of sapphire, in which the finite element method was employed to study the mechanical characteristic of sapphire under the nanoindentation process. The results demonstrated that the nanoindentation FE models were able to simulate the indentation loading-unloading curves of the sapphire. The load and unload displacement curves of the simulation and experiment results can match with each other well, and then the properties used in the simulation should be the actual properties of the sapphire. The Mises stress field distribution of the sapphire sample was calculated to reveal the alteration from elastic region to plastic region, which are useful for indentifying the ductile to brittle change in the sapphire abrasive process.

The Prediction of Material Removal and Surface Roughness of Workpiece during Abrasive Flow Machining

In order to study the finishing mechanism of abrasive flow machining (AFM), the model of material removal and solving method of surface roughness during material deformation have developed based on axial force and radial force. However, the axial force and radial force have been respectively measured by two pressure transducers fixed in the fixture. Both the material removal weight and surface roughness of workpiece have been calculated and measured during AFM experiments. The conclusions arrived by the analysis about the results of theoretical calculation are in agreement with the experimental AFM in some extent.

Research on Abrasive Flow Machining for the Outer Rotor of Cycloidal Pump

Abstract. In order to reduce the surface roughness and improve the manufacturing precision of the outer rotor surface of the cycloidal pump, the method that outer rotor tooth surface on the abrasive flow machining (AFM) is adopted. First of all, a power-law model to describe the form of abrasive flow was created, simulation analysis on AFM for the external rotor tooth surface, and the distribution of shear stress that the boundary layer abrasive subjected near the various parts of the outer rotor tooth surface can be draw. Then, choose abrasives with different particle size for processing. Experimental results demonstrate that tooth top, tooth surface and tooth root surface roughness Ra of the outer rotor from the 2.48um 2.192um and 2.107um down to processed 0.054um, 0.094um and 0.185um, material removal is 0.4g. AFM method can improve the manufacturing precision of the outer rotor, reduce the radial tooth tip meshing gap, reduce friction and wear of the tooth surface, extend the working life of cycloidal pump.

Numerical Simulation Analysis of Vibrating Screen’s Structure Vibration Property

Vibrating screen sifts materials via screen mesh, vibration displacement and velocity. In order to completing optimal design of vibrating screen’s vibration frequency. Firstly, Using the CAD function of the three dimensional software UG NX 6.0 to achieve vibrating screen modeling. Secondly, modal simulation analysis was carried out using the simulation soft NX NASTRAN. Numerical simulation experimental result indicates: this designed vibrating screen’s natural vibration frequency are 27.79Hz, 32.58 Hz, and 46.39Hz, consequently, designing this vibrating screen should avoid identical or approaching these natural vibration frequencies as far as possible, while choosing the vibration frequency.

Preparation and Processing Performance of Viscoelastic Abrasive Flow

Abstract. Abrasive flow machining (AFM) is an advanced technology which can improve the uniform consistency of profiled surface. First, the dielectric characteristics of the abrasive flow (the medium features include medium types, medium viscosity coefficient, the concentration of medium and abrasive, abrasive type, abrasive size) is studied, abrasive flow including different medium is deployed by mixing and mix well of the polymer silicone fluid, silicone oil, wax, and other fats, and adding silicon carbide with different particle size and mixed for processing experiment. Within the limits of the workpiece polishing, the change direction of the surface roughness and the removal rate of workpiece surface are substantially same and approaching the linear relationship, the lowest surface roughness Ra of SiC (abrasive particle size is 200#) reduced from 3.5μm to 0.5μm. The hardness and durability of the silicon carbide abrasive in this study is quite good, and the price is low, the processing characteristics are quite consistent with the economic costs on the demand.

Research on Process Parameters Influencing on Cutting Force in Abrasive Flow Machining (AFM)

In order to reduce the cost, improve the surface of workpiece machined by AFM and make out reasonable technological parameters of AFM, AFM theory model has been developed in the present work. The process parameters such as pressure, piston velocity, temperature and viscosity impacting on the workpiece surface quality have been researched. Firstly, the properties parameters of abrasive media such as viscous have been figured out with formulas based on the characters of abrasive media. And then the force between abrasive near to the workpiece surface and workpiece has been modeled with fluidics equations and dynamics equations. However, different parameter value leads to different force and different force has different surface quality (Ra) of workpiece. The calculation result is similar to the experiment result to some extent. Obviously, this model is helpful to establish the reasonable process parameters.