轴类件拔长锻透性及应力应变分析

发布时间：2018-05-27 19:11

本文选题：拔长 + V型砧　；参考：《安徽工业大学》2017年硕士论文

【摘要】：轴类大锻件的发展应用与各行业领域中大型设备的运转息息相关。用于生产大锻件的坯料,内部会存在不同程度的疏松、孔洞等缺陷,集中在中心轴线附近,影响锻件质量。而且随着坯料尺寸改变和重量的增加,坯料芯部缺陷更加严重。这些缺陷的存在直接影响了大锻件的运转和寿命期限。相对于其它生产工艺,锻造是改善和消除大型锻件芯部缺陷较为有效的方法。利用锻造方法来修复大锻件内部缺陷,就是要在有缺陷的区域上能够产生足够大的变形量和足够高的静水压应力,二者缺一不可。本文结合生产实际,应用有限元软件MSC.SuperForm对轴类大锻件拔长过程进行热力耦合数值模拟,分析了在多种拔长过程中锻件芯部锻透性和内部应力应变分布规律。研究表明,V型砧拔长,锻后锻件内部等效应变分布不均匀,各处变形差异较大,经三道次拔长后,锻件芯部锻透性较好,平均累积等效应变可达1.6。四砧径向锻造,锻件外层金属变形较大,芯部金属变形较小,锻件芯部锻透性较差,经四道次拔长后,端部中心最小等效应变小于0.2;中间部分等效应变较大,芯部累积等效应变为0.8左右。V型砧拔长,在拔长过程中锻件内部应力表现为两拉一压、两压一拉和三向压应力状态;四砧径向锻造,芯部周围始终存在轴向拉应力区域。无论是V型砧拔长还是四砧径向锻造,锻件芯部平均应力都为负,有利于芯部缺陷的锻合。为提高四砧径向锻造变形渗透性,本文还分析了四砧径向锻造过程中锤头的尺寸和形状、转速、压下量、轴向送进量等工艺参数对锻件芯部锻透性的影响规律,为轴类大锻件芯部缺陷的锻合提供参考依据。
[Abstract]:The development and application of shaft forgings are closely related to the operation of large equipment in various industries. For the production of large forgings, internal defects such as porosity and holes will exist in varying degrees, which are concentrated near the central axis and affect the quality of forgings. And with the change of the blank size and the increase of weight, the defects of the blank core become more serious. The existence of these defects directly affects the operation and lifetime of large forgings. Compared with other production processes, forging is an effective method to improve and eliminate the core defects of large forgings. In order to repair the internal defects of large forgings by forging method, it is necessary to produce large enough deformation and high hydrostatic stress in the defective region. In this paper, the thermo-mechanical coupling numerical simulation of the drawing process of large axial forgings is carried out by using the finite element software MSC.SuperForm, and the forging permeability and stress and strain distribution of the core in various drawing processes are analyzed. The results show that the internal equivalent strain distribution is not uniform and the deformation difference is great. After three times of drawing, the forging core has better forging permeability, and the average cumulative equivalent strain can reach 1.6. In the four anvil radial forging, the outer metal deformation of the forgings is large, the core metal deformation is small, the forging permeability of the forgings core is poor, the minimum equivalent strain of the end center is less than 0.2 after the four-pass drawing, the equivalent strain of the middle part is larger, The cumulative iso-effect of core is about 0.8. During the process of drawing, the internal stress of the forgings is shown as two tension and one press, two pressure and one tension, and three direction compressive stress, and the axial tensile stress region always exists around the core in the radial forging of four anvil. The average stress of the core of the forging is negative, which is beneficial to the forging of the core defect, whether the V-shape anvil is long or the four-anvil is radial forging. In order to improve the deformation permeability of four-anvil radial forging, this paper also analyzes the influence of the technological parameters such as the size and shape of hammer head, rotational speed, reduction amount and axial feed rate on the forging permeability of the forging core during the four-anvil radial forging process. It provides the reference for forging the core defect of the shaft type big forgings.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG316

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