Advanced Materials Research Vols. 53-54

Abstract: This paper analyses the material removal and surface forming mechanism of ultrasonic auxiliary gear honing. According to the Huygens principle of diffraction, a theory is proposed firstly that the ultrasonic waves transmit through the being honed gear in toroidal form, and the mathematical equation of the abrasive trace is built that expresses the relative movement between CBN abrasive and the gear surface. The equation is accordant with the experimental result. The paper concludes that the material removal of the gear surface depends on two factors, one is that CBN abrasives scratch the gear surface, and the other is that the gear surface vibrating itself along its normal direction impacts the abrasives.

Abstract: The contrast experiments between ultrasonic vibration honing and ordinary honing are firstly taken. It shows that the removal rates and the working accuracy of ultrasonic honing are much better than that of the ordinary honing. Then the optimum experiments on technological parameters of ultrasonic vibration honing on engine cylinder is taken, which gained the proper technological parameters. The experimental results indicate that the gained parameter totally meets the actual need and reaches a new height in this field, which provides the reliable technological parameter for the ultrasonic vibration honing to process cylinder and has a broad application in prospect.

Abstract: Ultrasonic vibration can reduce honing forces efficiently. As the honing wheel can be washed by ultrasonic cavitations of cutting fluids, its jams are decreased and the higher honing efficiency has been obtained. Therefore, gear honing combined with ultrasonic machining honing is a method for gear finish machining with its wide application future. Ultrasonic-assisted honing of gears is firstly proposed, its machining devices are manufactured based upon the design parameters derived by four-terminal network principle. Experiments of gear honing show that the machining traces on the tooth flanks in ultrasonic and traditional honing are different. The ultrasonic honing can produce a better tooth surface roughness (Ra 0.45 μm) than one obtained conventional honing (Ra 0.72 μm).

Abstract: Polishing is usually the last working procedure of making die surface. The roughness of die surface affects using performance of die directly; therefore, surface roughness is a key factor to scale quality of die surface. The paper focuses on affecting factors of polishing surface roughness, including the rotation speed of polishing head, floating force on polishing head, pass of polishing head movement, feeding rate of polishing head, and size of abrasive particles. Then, establish the parameters database in order to select appropriate technological parameters expediently. These results are used as operating guides for applications of die polisher.

Abstract: Potassium dihydrogen phosphate (KDP) crystal is widely used in navigates spaceflight, national defenses, energy sources and information technology fields based on its excellent nonlinear optical property. Surface quality of KDP crystal influences the property and life time of the device directly. So detection and analysis of the damage induced during machining process, especially on subsurface, should be solved. In this paper, surface damage of the KDP crystal, which machined from #600 grinding wheel with different feed rate, was detected by optical microscope. Cross section and selective etching were used to analyzing the subsurface damage. Because #600 grinding wheel mainly used in coarse grinding and the removal rate is high, the results shown that there was obvious scratch, crack and crushing on the machining surface. When the feed rate is 10+m and 40+m, the subsurface damage depth is 7.41+m and 8.96+m corresponding. This study is a kind of guide for following precision grinding, polishing machining time and removal amount.

Abstract: In high and super-high speed grinding process, there is an airflow layer with high speed around the circle edge of the grinding wheel that hinders the grinding fluid into contact layer, namely, the air barrier effect. The speed of airflow layer is directly proportional to the square of the wheel speed. Quick-point grinding is a new type of high and super-high speed grinding process with a point contact zone and less grinding power. The edge effect of the air barrier is weakened because the thin CBN wheel is applied in the process. By the analysis of dynamic pressure and velocity distributions in the airflow layer around the wheel edge, the mathematic models of the flow and jet pressure of grinding fluid for effective supply in the process were established and the process of optimization calculation of the jet nozzle diameter for green manufacturing was also analyzed based on the thermodynamics and the technical character of quick-point grinding process. The quick-point grinding experiment for surface integrity influenced by grinding fluid supply parameters was performed.

Abstract: The grinding wheel in the grinding process will surely become duller and duller. To find the reason for it is beneficial to optimize grinding process. The paper draws the graph of the Passivation process of grinding wheel by carrying grinding experiment in the condition of invariable grinding force. The curve can be divided into three parts according to the Passivation rate i.e. initial dull stages, regular dullness stages and rapid dullness stages. In the initial stages, the Passivation rate is lowest and the grinding efficiency is the greatest. The curve figure changes from concave to protruding，which is greatly different from wear curve of grinding process.

Abstract: This paper studies the grinding temperature field of dry belt grinding titanium alloys using finite simulation and experiments. A reasonable finite element model of dry belt grinding temperature field is established on the basis of ANSYS. And three kinds of boundary conditions are loaded on the element of a moving line heat source. The corresponding computer program is designed to calculate the temperature field for different grinding parameters, and the experiment results show that the simulated temperature have good agreement with the measuring ones. The model could be utilized to forecast the distribution and variation characteristics of the grinding temperature field under different conditions.

Abstract: In this paper, a new mathematical model and grinding method of ball-end milling cutter are proposed, based on the orthogonal spiral cutting edge curve. The movements of grinding wheel and ball-end milling cutter are presented while grinding rake face. In order to grind conveniently and avoid interference, a conical wheel is also designed and employed to grind the rake face of ball-end milling cutter on a grinder. In order to improve the machining characteristics of ball-end milling cutter, the model of rake face with equal rake angle is established. The software of ball-end milling cutter is developed to design and optimize different shapes of rake face. Furthermore, the simulation analysis on rake face with equal rake angle is carried out to confirm the validation of the mathematical models.

Abstract: Grinding is a very complex machining process. Single grain grinding methods are useful to study complex grinding action. Very low speed single-grain grinding tests were carried out for 45 steel and 20Cr alloy with 14# ZA grain. The grinding groove width and depth, the grinding force ratio, specific grinding forces, and grain wear and fracture are studied. The plowing decreases with the grinding section area or grinding depth increase. The average tangential force at grain fracture in the experiments is 54.4N; the average normal force at grain fracture is 949.6N. The ratio of tangential-to-normal force varies suddenly when grain fracture.