Abstract: Machine tool is the basic equipment of machinery industry, playing very important role in today's manufacturing, and its variety, quality and processing efficiency directly affects economic benefits and the technology level of the mechanical industry production. The modular machine tool is widely used in the industry, and its production efficiency is increased by several times or even several times than the common machine tool, with such processing methods of multi-axis, multi-knife and multi-process. This paper designs the small combined machine with a set of turning, milling, drilling and grinding by PTC's 3D software, namely Pro/Engineer. At last, the technique of the interference analysis and visual simulation has been carried on, verifying the feasibility of the machine design. The machine tool is mainly used to meet the needs of processing the small parts in scientific research, teaching unit or small repair industry, not only improving the machining efficiency, but also saving space and processing costs.
Abstract: Needle valve is the key component of diesel engine cylinder. Changing the nozzle Orifice chamferinging will influence the flow coefficient and spray performance. Firstly, we proposed a physical model of abrasive flow field inside the needle valve based on computational fluid dynamics technology. Then, we set the computing method and boundary type. Finally, we simulated the abrasive flow field using fluent software. The result is useful for guidance in the actual grinding process.
Abstract: This paper proposed a method to analysis an external flow-field around a Formula SAE car. Firstly, the body of Formula SAE car was designed conforming to the FSAE rules using CATIA. Then, the model of the external flow-field around the vehicle was established using computational fluid dynamic technology. A comparative analysis of the aerodynamic characteristics was made for the body between the conditions of being without the wing package and being with the wing package under different attack angle to get the static pressure graph, the lift force and the drag force then worked out the drag coefficient and confirmed which is the most suitable angle for the wings. The results showed that: the static pressure of the front body, the front part of the tires and the driver’s chest and head is the highest; the body has good streamline since its drag coefficient is 0.385; the rear wings can supply 65% downforce, when the attack angle of the rear wing is set to 8°. Finally, the real mold was fabricated according to the above 3D model and the analysis results. The method presented in this paper can provide theoretical basis and technical parameter for the aerodynamic formation designing and amelioration of the Formula SAE cars. Also it has guiding significance for the design and aerodynamic analysis of the Ordinary Passenger car.
Abstract: Plastic materials are widely used in automobile manufacturing, and they have different mechanical characteristics at high and low temperature, which has a major influence on automobile safety. This paper mainly studies the relationship between elastic modulus and yield strength of plastic materials at high and low temperature, in order to predict the elastic modulus by the yield strength. On this basis, the values of the parameter of the constitutive model will be predicted to obtain the constitutive equation. The method meeting the precision is validated by the experiments. The method decreases experimental working, and provides technical support for product development as well.
Abstract: Hybrid measurement method is proposed to solve the problem that the partial or whole three-dimensional reconstruction accuracy of aviation engine parts is high. The point clouds of the aviation engine part are captured first using contact and non-contact measuring method. Feature-based parametric modeling strategy is adopted to reconstruct the aviation engine part so that it is easy to be modified in the future. Then, the point cloud data obtained by contact measurement and the reconstructed model are registrated to the same coordinate system to detect the deviation. The point cloud registration method is based upon the feature-based registration method and standard Iterative Closest Point (ICP) algorithm, which help to improve the accuracy of registration. According to the result of deviation, the three-dimensional model can be modified. The accuracy of the modified model is controlled within 0.02mm, satisfying the requirement of aviation engine parts. Three-dimensional reconstruction results have verified the feasibility of the method.
Abstract: The meshing force between pin wheels and gear teeth of modified and standard cycloidal gears is calculated. The parametric model of cycloidal gear and pin wheels is built. The flexible processing of cycloidal gear and pin wheel is conducted using Ansys software. The virtual prototype of cycloid reducer is built. The dynamic simulation of rigid-flexible coupling of modified and standard cycloidal gears has been developed, respectively. The meshing force with friction is calculated and the maximum equivalent stress is obtained. A comparison study of the meshing force using theoretical method is also carried out. It is significant to provide theoretical and technical supports for cycloidal gear design.
Abstract: An method was proposed to derive the formula of the overlap coefficient and the influence of main parameters on overlap coefficient were also discussed; The load distribution is deduced and the rule of contact load varying with overlap coefficient was revealed; The results indicate that the increasing overlap coefficient can extend the time of rollers engaging, reducing the contact load of globoidal indexing cam mechanism and altering the load distribution.
Abstract: Spray quality of Multi-hole nozzles decides the quality of diesels, but the control of spray is a hard work in the field of internal combustion engines. The spray quality can be changed by abrasive suspend jet which is a flexibility manufacturing method and the quality will vary with system pressure, abrasive kind, diameter of abrasive, preparation method, viscosity of working medium and grinding allowance and some other parameters. This paper tries to optimize the spray quality of nozzles by using orthogonal experimental design to select the values of these parameters. To evaluate the quality of spray, a scoring method was offered and input parameters were organized to three parameters before experiment. According to the orthogonal table of factor level (L16(45)), the line charters between the parameters and the spray quality was shown. This paper considers that the optimal combination is A2B2C2. Then the relationship between spray quality and the parameters optimized is deduced. And the significance of the forum was checked, it shows that the forum was significant at level α=0.01.
Abstract: The melting of the material is regarded as the moving boundary problem of the heat conduction equation. In this paper, the method of fundamental solution is extended into this kind of problem. The temperature function was expressed as a linear combination of fundamental solutions which satisfied the governing equation and the initial condition. The coefficients were gained by use of boundary condition. When the metal wire was melting, process of the moving boundary was gained through the conversation of energy and the Prediction-Correlation Method. A example was given. The numerical solutions agree well with the exact solutions. In another example, numerical solutions of the temperature distribution of the metal wire were obtained while one end was heated and melting.