Research On The Key Technology Of Low-rigidity Parts Cutting Auxiliary Support

In the new century, the low rigidity parts are widely used in aerospace, defense and production of modern people’s lives, such as low stiffness slender shaft parts. Due to the low rigidity parts are interacted to produce size error easier in the cutting process by cutting force,cutting heat, cutting stress, so the low- rigidity parts are difficult to be machined. At present mainly rely on the experienced operator to improve the machining quality of low rigidity of slender shaft, and due to the lack of effective theoretical guidance, the quality of low rigidity part machining is very difficult to guarantee and the processing efficiency is not high.Therefore, the low stiffness of slender shaft machining is studied in this paper, and the main research is as follows.Studying the mechanism of cutting forces and the main factors affecting the cutting forces. The stress, strain, cutting force, cutting heat and chip forming process of the slender shaft in the cutting process is simulated by use of the finite element software DEFORM. The simulation results of the cutting force showed that the main cutting force was the largest, feed force was followed and backward force was minimal. And in the cutting process, the cutting force increased rapidly to a value. Then, with the processing, the cutting force fluctuated up and down near the value.This paper uses the impact characteristics of water jet, not destruction of slender shaft material as the premise, the application of water jet technology in the auxiliary of slender shaft supporting cutting, so that the impact force of water jet offsets the cutting force of slender shaft machining, thereby increasing its stiffness, reduce the size error. This paper analyzes some basic theories and impact properties of water jets, mainly for liquid flow rate at the nozzle exit, power, flow and pressure impact on the workpiece, and get the formula of these parameters of the theory, and the use of CFD software FLUENT to simulation of nozzle flow field impact characteristics, analyze the influence of different jet pressure, spray distance,and nozzle diameter to jet impact pressure and impact regional.We established a working mechanical model of slender shaft about jet auxiliary supportor, in-depth analyzed and established the mathematical model of size error of slender shaft with and without jet auxiliary supportor. Based on this model we can see, slender shaft turning in water jet auxiliary supportor is good to reduce the size error. In this paper several vibration model of slender shaft is analyzed. We establish the free vibration equation of slender shaft and the forced vibration equation of slender shaft which is under the cutting force and jet impact force, according to the established equation we are known, jet auxiliary support technology can reduce forced vibration well which due to the cutting force of slender shaft.Through the experiment to verify the correctness of jet aided support of slender shaft processing model, we get a size error with or without jet auxiliary supportor of slender shaft,and further analyze of the influence of cutting parameters and jet parameters on size error of slender shaft. Due to the selected machining process parameters of low stiffness slender shaft is smaller than ordinary axis’ s, so it needs multiple passes slender shaft to complete theprocess, and the slender shaft machining efficiency is low. We use a modified artificial bee colony algorithm to optimize machining parameters of slender shaft, and establish mathematical model of optimum slender shaft machining parameter. We add constraints based on the requirements of designers on the machining accuracy of slender shaft, which not only can ensure machining quality of slender shaft, but also can greatly improve the production efficiency.