爆燃冲击波对热能去毛刺的影响研究

发布时间：2018-07-03 16:10

本文选题：热能去毛刺 + AutoReaGas　；参考：《中北大学》2012年硕士论文

【摘要】：在机械加工过程中，，工件的表面往往会产生许多不同形状以及厚度的毛刺，毛刺很小但危害很大，有时甚至会导致安全事故。所以，安全有效的去除毛刺已成为工件加工过程中的一道关键工序。而热能去毛刺法可以有效快速的去除不同材料工件的毛刺，在去毛刺领域具有很高的实际应用价值。虽然热能去毛刺法的工艺水平日趋成熟，但是系统的研究热能去毛刺机理以及预混合可燃性气体燃烧爆炸后，爆燃冲击波对工件及毛刺的影响缺乏有效、科学的数据。本文以氢氧混合气体作为热能去毛刺中的预混合气体，应用CFD流体力学软件AutoReaGas以及后处理软件AutoDyn，通过建立具体的爆炸缸数学模型，建立了不同的工件以及毛刺尺寸的数学模型，划分网格，设置不同的初始条件，采用湍流燃烧模型，基于Navier—Stokes方程进行仿真计算，并对不同参数下氢氧预混合可燃性气体燃烧爆炸产生的结果进行分析，总结不同参数对热能去毛刺法的适用性并得出如下结论：（1）工件尺寸小范围变化对预混合可燃性气体爆燃冲击波的影响很小。所以工件面与体积之比越大，单位时间内吸收的热量就越多，经研究发现，在工件面与体积之比大于20以上的时候，利用热能去毛刺法会破坏金属工件表面的金相组织；（2）毛刺厚度的大小影响着爆燃冲击波的超压、温度以及速度。毛刺越厚，其爆燃冲击波的超压、温度以及速度也就越大。经研究发现，在毛刺厚度与工件薄壁处的比值大于0.1的时候，利用热能去毛刺会破坏金属工件表面的金相组织；（3）在利用热能去毛刺过程中，预混合可燃性气体混合比的变化影响其爆燃冲击波的超压、温度、化学反应速率以及速度。其预混合可燃性气体的混合比为当量比时，爆燃冲击波的各项参数均为最大值。同时给出了不同材料工件需要的预混合可燃性气体比值的适用范围；（4）在利用热能去毛刺过程中，预混合可燃性气体初始压力的变化影响其反应速率、爆燃冲击波产生的超压；并且预混合可燃性气体燃烧爆炸后的超压与初始压力呈近似的线性关系；但是，预混合可燃性气体燃烧爆炸产生的温度和冲击波的速度并不随着初始压力的增加而变化；同时给出了不同材料工件需要的初始压力的适用范围；（5）工件装填密度的大小直接影响着预混合气体燃烧爆炸后的超压、化学反应速率、温度和爆燃冲击波的速度。工件装填密度越大其预混合气体燃烧爆炸后的超压、化学反应速率、温度和爆燃冲击波的速度也就越小。本论文研究所取得的成果可为今后的工程应用以及安全生产提供一定的理论指导。
[Abstract]:In the process of machining, many burrs with different shapes and thickness are often produced on the surface of the workpiece. The burrs are small but harmful, and sometimes even lead to safety accidents. Therefore, the safe and effective burr removal has become a key process in the process of workpiece processing. The thermal deburring method can effectively and quickly remove the burrs of different materials, which has a high practical value in the field of deburring. Although the technology level of thermal energy deburring method is becoming more and more mature, the mechanism of thermal energy deburring and the effect of deflagration shock wave on workpiece and burr after combustion explosion of pre-mixed combustible gas are studied systematically. In this paper, the mixture of hydrogen and oxygen is used as the premixed gas in the thermal energy deburring. By using the CFD fluid dynamics software AutoReaGas and the post processing software AutoDyng, the mathematical models of different workpieces and burr sizes are established by establishing a specific mathematical model of the explosion cylinder. With different initial conditions, the turbulent combustion model is adopted and simulated based on Navier-Stokes equation. The results of combustion and explosion of hydrogen and oxygen premixed combustible gas under different parameters are analyzed. The applicability of different parameters to the thermal deburring method is summarized and the following conclusions are drawn: (1) the influence of the small range of workpiece size on the deflagration shock wave of pre-mixed combustible gas is very small. Therefore, the larger the ratio of workpiece surface to volume, the more heat is absorbed in unit time. It is found that when the ratio of workpiece surface to volume is more than 20, the metallographic structure of metal workpiece surface will be destroyed by using thermal energy deburring method. (2) the thickness of burr affects the overpressure, temperature and velocity of deflagration shock wave. The thicker the burr, the greater the pressure, temperature and velocity of the deflagration shock wave. It is found that when the ratio of burr thickness to workpiece thin-wall is greater than 0.1, the metallographic structure of metal workpiece surface will be destroyed by thermal energy deburring. (3) in the process of thermal energy deburring, The change of mixing ratio of premixed combustible gas affects the overpressure, temperature, chemical reaction rate and velocity of deflagration shock wave. When the mixing ratio of premixed combustible gas is equivalent, the parameters of deflagration shock wave are all the maximum. At the same time, the applicable range of the ratio of pre-mixed combustible gas required for different materials and workpieces is given. (4) the change of initial pressure of pre-mixed combustible gas affects its reaction rate in the process of burring with thermal energy. The overpressure caused by deflagration shock wave and the linear relation between the overpressure and the initial pressure after combustion explosion of premixed combustible gas; however, The temperature and velocity of shock wave produced by combustion explosion of pre-mixed combustible gas do not change with the increase of initial pressure, and the applicable range of initial pressure for different materials is given. (5) the filling density of the workpiece directly affects the overpressure, the chemical reaction rate, the temperature and the deflagration shock wave velocity after the combustion and explosion of the premixed gas. The higher the loading density of the workpiece, the smaller the overpressure, the chemical reaction rate, the temperature and the velocity of the deflagration shock wave after the combustion and explosion of the premixed gas. The results obtained in this paper can provide some theoretical guidance for engineering application and production safety in the future.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH161.14;TG66

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