发动机高精度螺纹孔加工技术研究

发布时间：2018-10-20 12:59

【摘要】：发动机曲柄上螺纹孔的加工是零件加工的关键工序。然而传统的加工方法存在着精度低、刀具易损坏等缺点,所生产的螺纹也存在着烧结、松动等问题,存在重大安全隐患,而且需要人工修整,效率较低。通过对比各种加工方法,选定螺纹铣削工艺为最终方案。螺纹铣削方法对比其他工艺,具有效率高、精度高、成本低等优点,且适用于批量生产。但是由于铣削需要三轴联动数控铣床,因此一直未能广泛应用,随着数控设备的普及,螺纹铣削工艺的应用日益广泛。本次项目设计了螺纹铣削的工艺流程,结合刀具知识和生产实际,选择合适的螺纹铣刀,并根据其加工原理编制数控加工程序。通过应用正交试验方法,确定螺纹铣削加工中的关键参数,以实现提高加工质量与效率的目的。试验以切削速度、每齿进给量、背吃刀量为影响因素,每个因素选取4个设计水平,以螺纹牙的粗糙度为实验指标。在数控铣床上进行加工实验,用螺纹塞规检验其合格性,用粗糙度仪测量螺纹牙粗糙度。并对实验结果分别进行直观分析和方差分析,确定各因素对指标的影响大小。分析结果表明,在螺纹铣削加工中因素的影响大小依次是:每齿进给量,切削速度,背吃刀量。之后,对每齿进给量进行单因素优化,确定最优参数组合。在试验的基础上,确定了表面粗糙度的预测模型。由于螺纹孔和螺栓强度直接影响发动机的正常运转,所以本文对平衡块与螺栓随曲轴运动的过程进行受力分析和计算,并通过UG软件对其建模。通过运用有限元分析软件ANSYS对螺纹孔和螺栓进行受力仿真和分析。并应力分布规律为基础,提出了对现有螺纹设计的改进措施。
[Abstract]:The machining of threaded holes on engine crank is the key process of machining parts. However, the traditional machining methods have some shortcomings, such as low precision, easy damage of cutting tools, and the problems of sintering and loosening of thread produced, which have great safety hidden trouble, and need manual dressing, so the efficiency is low. Through the comparison of various processing methods, the thread milling process is selected as the final scheme. The thread milling method has the advantages of high efficiency, high precision and low cost, and is suitable for mass production. But because milling needs three-axis linkage NC milling machine, it has not been widely used. With the popularization of numerical control equipment, thread milling technology is increasingly widely used. The process of thread milling is designed in this project. According to the knowledge of cutting tool and production practice, the suitable thread milling cutter is selected, and the NC machining program is compiled according to its machining principle. In order to improve the quality and efficiency of thread milling, the key parameters of thread milling are determined by means of orthogonal test. In the experiment, cutting speed, feed rate per tooth and the amount of back feed knife were taken as the influencing factors, 4 design levels were selected for each factor, and the roughness of the thread tooth was taken as the experimental index. The machining experiment was carried out on the NC milling machine, the thread plug gauge was used to test its eligibility, and the roughness of the thread tooth was measured with the roughness meter. The experimental results were analyzed by visual analysis and variance analysis to determine the influence of each factor on the index. The results show that the influence of factors in thread milling is as follows: feed per tooth, cutting speed and back feed. After that, the feed rate per tooth is optimized by single factor, and the optimal parameter combination is determined. On the basis of experiment, the prediction model of surface roughness is established. As the strength of thread holes and bolts directly affect the normal operation of the engine, the force analysis and calculation of the balance block and bolt with the crankshaft movement are carried out in this paper, and the model is established by UG software. The finite element analysis software ANSYS is used to simulate and analyze the stress of thread holes and bolts. On the basis of stress distribution law, the improvement measures of thread design are put forward.
【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK406;TG62

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