Advanced Materials Research Vols. 154-155

Abstract: Generating line method for designing and manufacturing spiral bevel gears is proposed in this paper. The tooth surface of spiral bevel gears produced by generating line method is formed by exact spherical involutes, the mathematical model to describe tooth surface has been derived based on gear meshing theory and the cutting motion. This study can provide some fundamentals for manufacturing and contact analysis of spherical involutes spiral bevel gears.

Abstract: Being the heat source of arc spray, the characteristics of arc are of importance for properties of coatings. In this paper, the arc shape in the wire arc spray process was analyzed in the aid of high-speed digital camera. It is testified that the arc has the elliptical shape. This type of shape is favorable for heating the metal particles. The arc isn’t always in burning state and it is extinguished frequently. There are two kinds of reasons for arc extinguish. The first one is that the two metal wires short circuit. The second one is that the imperfect melted metal stretches the arc long, and then this part melted and broken away from the metal wires’ tips. If we can control the metal wires state, the properties of coatings will be improved.

Abstract: Generating line method, which is based on the generating process of spherical involute curve, is a new processing theory of cutting ideal spherical involute gears. This paper proposed the geometry and basic principle of cutting hypoid gears by this method, and defined the planar conjugated relationship between generating lines of the pinion and gear. A mathematical model of tooth surfaces is established based on cutting process. This model can be applied to any shapes and parameters of the gear generating line.

Abstract: In this paper, the structure design and operating principle is introduced to micromachined gyroscope with electrostatic drive and piezoresistive detection. In the paper, the piezoresistive effect of multi-barrier nano-film is used as detection method, which achieves high piezoresistive sensitivity compared with Silicon piezoresistive device. The gyroscope structure and multi-barrier nano-film device is fabricated by using heteroepitaxy GaAs film on Si substrate which implements the process compatible. The natural frequencies of gyroscope are determined from the modal analysis.

Abstract: The interatomic exchange interactions and the electronic structure of Co-doped ZnO with and without oxygen vacancy have been investigated by the first-principles calculations based on density functional theory. It is found that the oxygen vacancy can strengthen the ferromagnetic exchange interaction between Co atoms and might be available for carrier mediation. The oxygen vacancy near to the Co atoms is more favorable for the ferromagnetic ground state.

Abstract: Based on Gaussian process (GP), a new parameters’ correlation analysis method for injection molding is proposed. Referred to the design idea of canonical correlation analysis (CCA), GP is used to extract accurate canonical correlation variables simultaneously from two data sets. And then the canonical correlation variables are used to analyze the correlation between parameters and design objectives. The cross member under windshield of a van is taken for a case. For the weld lines defects produced in injection process, the correlation of process parameters is analyzed to identify which parameters are more related to weld lines. The validity of this method is proved by the optimal result. And this provides strong theory and feasible algorithm for adaptive intelligent optimization and controlling of the parameters in injection process.

Abstract: The mathematic model of the flow press sever-valve was built in this paper, during the process of building the model, the author took into account the load moment brought by the pair of spray nozzles flow force and the load moment brought by the force couples back pole and the fundamental equation of the force moment motor. On the other hand, the author analyzed the influence of the nonlinear factor to system performance, and the nonlinear factor was valve port overlap length disaccord caused by machining error. The mathematic model of the electro-hydraulic force control system controlled by the flow press servo-valve with valve port error was built. The results of simulation and experiment showed that valve port error badly influenced the system performance, and that valve port error was the main reason of the pressure higher than the supply pressure, which is one of the two cylinder cavities. The simulation curve and the experiment curve were accord compared by system simulation and experiment results, so we can know that the mathematic model of the flow press sever-valve and of the electro-hydraulic force control system controlled by the flow press servo-valve is correct.

Abstract: The closed hot precision forging process of a bevel gear with large cone angle was studied. According to the structure features of the bevel gear, two types of relief forging processes were proposed. First, simulations based on thermal-mechanical coupling finite element model were performed with Deform3D. Then the corresponding experiments were conducted and the results perfectly matched the simulation results. The advantages and deficiencies of two processes were discussed and a reliable basis for selecting the optimal process was proposed.

Abstract: Ti-6Al-4V laser cladding layers were performed on the Ti substrate respectively based on four different laser scanning ways by laser cladding with coaxial powder feeding. The results showed that the morphology of cladding layers in heat overlapping was much smoother than cold overlapping. The possibility of appearance of concave-convex would be increased in the laser cladding performed with reverse scanning direction. However with same direction scanning the possibility of distortion of the substrate would increase. The microstructure of cladding layers in four scanning ways all exhibit epitaxial growth huge columnar β grains in which fine acicular α and Widmanstaten α lath are distributed. The columnar β grains and fine acicular α formed during cold overlapping were denser than during heat overlapping. Also the microhardness of laser cladding zone was improved compared to the substrate no matter in which scanning way while the microhardness in cold overlapping was higher than that in heat overlapping in the same position of cladding zone.

Abstract: Deformation of round castings due to thermal and/or mechanical strain may lead to the occurrence of their ovality defects during continuous casting. Presently, ovality defect from thermal deformation have been effectively controlled in actual casting process with the application of more advanced equipments and more sophisticated control strategies. But the control of ovality defect from larger mechanical deformation still cannot satisfy the need of caster design or higher qualified rate of castings. It is shown that excessive hot pressure while strand passes through tension leveler, is the main reason to generate larger mechanical deformation. With consideration of the characteristics of round caster and the requirement of safety production, a theoretical calculated model based on mechanical deformation analysis has been developed in the paper to eliminate ovality defect specially from the over large hot pressure. Calculation analysis suggests that groove design of drive roller and range of round section sizes should be the important consideration for the determination of hot pressure, and there always exists an optimum value for hot pressure when the machine equipments of round caster have been designed and installed. The model can provide a useful guideline for casting engineers to design the groove of drive roller and to determine reasonable safe hot pressure. Reliability of the model analysis has been verified by industrial application on a newly built round caster.