Advanced Materials Research Vols. 53-54

Abstract: This study using ultrasonic energy transmitted into the electrolyte to assist in discharging of electrolytic product out of the machining gap in the compound finishing processes of electrochemical finishing and burnishing on hole-wall surface beyond traditional process of holes machining instead of conventional hand or machine polishing. The design finish-tool includes a burnishing-tool and an electrode as a hole-wall surface finish improvement that goes beyond traditional rough boring. In the experiment, the finish-tool travels across the hole-wall surface with continuous or pulsed direct current. The experimental results show that the large supply of current rating is effectively to reach the amount of the material removal and is advantageous to the finishing processes. The average effect of the ultrasonic is more better than the pulsed current while the machining time needs not to be prolonged by the off-time. The finish effect is better with a high rotational speed of the finish-tool because the dregs discharge of electrochemical finishing becomes easier and is also advantageous to the finish. The compound processes of burnishing and ultrasonic electrochemical finishing just require a short time to make the hole-wall surface smooth and bright.

Abstract: Two-phase compulsive circulation flows finishing is put forward mainly for hole surface. By theoretic analysis, flows field characteristics will directly affect finishing quality and efficiency. On the basic premise of defining k-ε model, numerical simulation of field flows are made, and structure parameters of the nozzle are analyzed, which provide theoretic basis for thorough research.

Abstract: At present, crankshafts are finished mostly by abrasive cloth and manual steel brush, which is not ideal on finishing quality, efficiency and cost, especially cleanness degree does not meet design and use request. So horizontal spindle barrel finishing has been developed. Based on its finishing theory, process characteristics are key factors affecting the finishing effect, especially finishing uniformity. Process characteristics of motion parameters, finishing depth, finishing time, etc. are analyzed, and reasonable parameters are defined. It provides basis for industry application of this process.

Abstract: From the viewpoint of the change of the anodic surface microtopography in the process of Electrochemical Finishing (ECF), this paper studies the anodic smoothening mechanism of ECF and puts forward the directional issue of the dissolution of anodic surface in the microtopography sense. On condition that the anodic material is dissolved along with the normal direction of the micro-profile on the anodic surface, the influence of wave length of the micro-profile on the smoothening effect is discussed in detail and the mathematical model based on the “lateral direction dissolution” is established. Finally, ECP is taken as the example and the experiment is carried out, the result shows that the smoothening rule obtained by experiment accords with that by calculation.

Abstract: The mechanism of electrochemical finishing machining (ECFM) process was investigated. Some vital procedure parameters involving in ECFM process, such as operating voltage, electrolyte component and concentration，machining temperature, electrode gap and current density were also evaluated and optimized, and then these optimized machining process parameters were applied in ECFM experiments for promoting surface quality. In this study, two typical types of workpieces, stainless steel rod and aero-engine blade, were selected to evaluate the validity of ECFM. Furthermore, the important surface roughness characteristics before and after ECFM process such as height and spacing characteristics of surface roughness, surface waviness characteristics, surface microscopic appearance and light reflection characteristics were compared. The experiment and measurement results indicate that ECFM process can distinctly improve surface quality, eliminate the surface scratch marks and defects and reduce surface roughness.

Abstract: Hard-brittle materials can be polished by hydrodynamic suspension, which is based on the theory of sound eradiating. Owing to the high-speed rotating of the polishing tool, the polishing slurry would form dynamic pressure in the clearance between the work-piece and the tool. The dynamic pressure supplies abrasive particles the energy needed to impact on the work-piece surface, so the dynamic pressure will directly affect the machining effect. In order to obtain the steady and consistent machining quality, it’s necessary to implement the compliant control in the machining process, and adjust the dynamic pressure when needed. This paper utilizes piezoelectric ceramic micro-displacement actuating to investigate the technique that can achieve the control of micro-displacement between the polishing tool and the work-piece. It provides an effective mean for hydrodynamic slurry pressure in the hydrodynamic suspension ultra-smooth machining.

Abstract: The integration manufacturing technology is a kind of compound precision finishing process that combined grinding with abrasive jet finishing, in which inject slurry of abrasive and liquid solvent into grinding zone between grinding wheel and work surface under no radial feed condition when workpiece grinding were accomplished. The abrasive particles are driven and energized by the rotating grinding wheel and liquid hydrodynamic pressure and increased slurry speed between grinding wheel and work surface to achieve micro removal finishing. In the paper, the machining process validity was verified by experimental investigation. Experiments were performed with plane grinder M7120 and workpiece material 40Cr steel which was ground with the surface roughness mean values of Ra=0.6μm. The machined surface morphology was studied using Scanning Electron Microscope (SEM) and metallography microscope and microcosmic geometry parameters were measured with TALYSURF5 instrument respectively. The experimental results show the novelty process method, not only can obviously diminish longitudinal geometry parameter values of ground surface, but also can attain isotropy surface and uniformity veins at parallel and perpendicular machining direction. Furthermore, the finished surface has little comparability compared to grinding machining surface and the process validity was verified.

Abstract: According to the motion features of abrasive particles and workpieces in centrifugal roller, considering the abrasive particles and workpieces as two kinds of ball particles with different materials and sizes, 3-Dimensional Discrete Element Method (DEM) was used to build the dynamics model of single abrasive particles and workpieces motion. Based on such model, in this paper, the influence of rotation-revolution ratio on medium movement was mainly analyzed. Supposing filling ratio as 20%, mixing ratio as 1.5:1 and revolution speed as 180r/min, the movement procedure of medium within centrifugal roller was respectively simulated under the different cases of rotation-revolution ratio as -0.13, -1 and -2, then the velocity variation diagram and the average contact forces diagram for abrasive particles or workpieces under different rotation-revolution ratio were obtained, the simulation results are basically coincident to the experimental results. Both results have proved that rotation-revolution ratio is the main parameter that changes medium motion law, which provides a very efficient way to further optimize design parameters and process parameters, as well as to improve production efficiency.