Study On Cutting-Extrusion Shaping Technology And Its Experiments

Fin tubes are widely used in industrial practice. How to get a good heat transfer fin structure is widely concerned in the area of engineering. A new cutting-extrusion composite shaping technology that uses the conventional machine tools and special grinding cutting tools to make the chips in traditional machining plough up, deform and erect become integral spiral type fins erecting on the tube body through selecting appropriate machining parameters and geometric parameters of cutting tools is advanced in the thesis.Taking the fin tubs and plane fins as researched objects, the kinematical relation of cutting-extrusion composite shaping process and the structure feature of the cutting tool were researched, the principle of shaping process and its geometric model were obtained, the point view that the cutting-extrusion process can be divided into three stages:cutting, extrusion and plough up was advanced based on those, the theory calculation formula between the fin structures and process parameters was established.Factors impacting on the structure and size of fin were analyzed, the relationship between quantity used in cutting, cutting-tool angle and fin structures was systemically researched, the fin shaping conditions and the law of structural changes in size were obtained, the design principle of the cutting tools and the reasonable geometric angle scope were presented, those lay a foundation for practical application.Based on method of rigid-plastic FEM, a three-dimensional FEM's analysis model of cutting-extruding integral shaping process was built, the key problems such as chip-body separation rule, mesh distortion, etc. in simulation were analyzed, the statics analysis was carried out by using the Ansys FEM method, the distributing rules of stress and strain inside of fin were gained, and the fin separation criterion was presented. Using the software of the finite element method Deform-3D, the dynamic shaping process of the fin was simulated. The simulation of fin structure, dimension consistent with the theoretical analysis were obtained as well as the distribution of fin stress and strain field, the important reference for the experimental study was provided. Aiming at the vertical fins, the experimental researches at different cutting parameter and tool geometrical parameters were made, the effect law of technical parameters affecting fin geometrical dimension was obtained, the empirical equations of fin high and thick dimension were gained, Through copper and aluminum material, the fin's shaping scope at different cutting parameters was achieved by copper and aluminum material cutting-extrusion experiments; the differences between the actual fins tip structure and of the ideal shape were analyzed as well as the impact factors of fin accumulation, fin bending and fin upright reason, the whole process parameters of cutting-extrusion shaping and the method of parameters matching were acquired.Through cutting-extrusion shaping theoretical analysis and experiment researches, the analytical model of cutting-extrusion was built up. The copper and aluminum material fin shaping empirical formula of cutting-extrusion force was obtained. The experiment results showed that the three direction force is bigger than common cutting force using the shaping method, the extrusion force play main role at the same cutting parameters, making the opposite direction of axial force and that of common cutting; those have good guide meaning to the tool design and equipment adjustment.The simulation and experimental research on the heat exchanger of cutting-extrusion fin tube were carried out, the fin tube structural parameters and the effect of inside and outside of fin tube were analyzed, the laws of the fin space, thickness and height and of the outside of fin tube at different fluid effecting on heat transfer are obtained, the correctness of the numerical simulation was verified through experiments, which provides the basis of fin parameters structure optimization and the guidance of cutting-extrusion shaping process.