板料压扁成形研究及在压扁精冲复合成形工艺中的应用

发布时间：2018-06-08 03:38

本文选题：板料压扁 + 成形力　；参考：《重庆理工大学》2017年硕士论文

【摘要】：板料压扁成形是综合体积成形和板料成形特点的一种工艺,一方面具有体积成形的三维特征即厚度差,另一方面作用对象是厚度较薄的板料,该工艺具有节省材料、强化基体的特点。在板料压扁过程中,根据零件的尺寸和形变,凸模上会被施加非常高的压力,可能导致过载,从而造成模具开裂或者产生疲劳裂纹。由于现存的压扁经验公式的误差较大,针对板料压扁成形力大的特点,为了获取准确的压扁力公式,为了模具设计和压力机选型展开以下研究。首先,根据零件和模具的几何特点对板料压扁进行分类和特点分析,运用有限元软件deform对实心板、空心板、外环局部板和内环局部板压扁过程中的速度场,应力场,应变场进行了分析,一方面得到板料压扁工艺中金属材料流动的规律特征,另一方面获得板料压扁材料中的应力和应变分布以及扩展规律。其次,采用正交实验方法,以实心板料压扁成形力为对象,对材料、直径、厚度以及摩擦系数四个影响因素进行重要性分析,随后采用控制变量法进行各个因素的单一分析,得出各个因素对成形力的影响规律,为压扁力公式的提出奠定基础。通过对棒料镦粗成形力、闭式模锻的变形抗力和摩擦力、压扁力经验公式的研究以及结合板料压扁本身特点提出实心和空心板料压扁成形力的数学模型,经过模拟反推得出关键系数m,结合工艺试验进行验证对系数m进行修正;对于内环局部压扁和外环局部压扁采用剪切力加上墩压力的方法计算得出。最后,通过MATLAB对于20钢的流动应力曲线进行拟合,以此来计算一次能够下压的压扁量最大值,进而针对零件要求计算压扁次数;针对压扁力大的问题,根据零件的几何特征采取合适的分流降压措施,并对分流降压进行了分析比较;结合磁盘架对压扁在精冲压扁复合成形中的应用进行工艺分析。主要工作包括:板料压扁特征分析,速度场等各种场量结果分析,压扁力的影响因素重要性排序以及数学模型构建,进行物理实验修正以及精冲压扁复合成形工艺研究。以上研究成果具有一定的科研价值和工程意义,为板料压扁在精冲压扁复合成形提供一定意义的技术指导。
[Abstract]:Sheet metal flattening is a process that integrates the characteristics of bulk forming and sheet metal forming. On the one hand, it has the three-dimensional characteristics of volume forming, that is, thickness difference, on the other hand, the action object is thin sheet metal, which can save materials. Strengthen the characteristics of matrix. In the process of sheet metal flattening, according to the size and deformation of the parts, the punch will be subjected to very high pressure, which may lead to overload, which may lead to die cracking or fatigue crack. Due to the large error of the existing flattening empirical formula, in order to obtain the accurate flattening force formula, die design and press type selection, the following research is carried out in view of the characteristics of the sheet metal flattening forming force. Firstly, according to the geometric characteristics of parts and dies, the flattening of sheet metal is classified and analyzed. The velocity field and stress field of solid plate, hollow plate, outer ring local plate and inner ring local plate are analyzed by using finite element software deform. On the one hand, the characteristics of metal material flow in sheet metal flattening process are obtained; on the other hand, the stress and strain distribution and propagation law in sheet metal flattening material are obtained. Secondly, the importance of four factors, such as material, diameter, thickness and friction coefficient, is analyzed by orthogonal experiment method, and the single analysis of each factor is carried out by controlling variable method. The influence of various factors on forming force is obtained, which lays a foundation for the formulation of flattening force. Based on the research of the forging force of bar, the deformation resistance and friction force of closed die forging, the empirical formula of flattening force and combining with the characteristics of sheet metal flattening, the mathematical model of solid and hollow sheet flattening forming force is put forward. The key coefficient m is obtained by the simulation and back extrapolation, and the coefficient m is corrected by the process test. The method of shear force and pier pressure is used to calculate the local flattening of the inner ring and the local flattening of the outer ring. Finally, the flow stress curve of steel 20 is fitted by MATLAB to calculate the maximum flattening amount which can be pressed at a time, and then to calculate the flattening times according to the requirements of the parts, and to solve the problem of large flattening force. According to the geometric characteristics of the parts, appropriate measures of shunt pressure reduction are adopted, and the shunt pressure reduction is analyzed and compared, and the application of flattening in the fine punching flattening composite forming is analyzed in combination with the disk frame. The main work includes: analysis of flattening characteristics of sheet metal, analysis of the results of various fields such as velocity field, ranking of influencing factors of flattening force and construction of mathematical model, modification of physical experiments and research on the process of fine blanking flattening composite forming. The above research results have certain scientific research value and engineering significance, and provide some significant technical guidance for sheet metal flattening in fine punching flattening composite forming.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

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