套管叉热成形三维有限元模拟分析与实验研究
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摘要
套管叉是长安SC6350微型汽车传动系统的重要零件，由于套管叉属长轴分叉类锻件，形状较复杂，材料变形较困难，之前人们对其热成形过程的研究尚未深入，其生产用模具结构并未达到最优化。因此，采用三维有限元数值模拟技术，对套管叉热成形过程及其成形规律进行深入的研究，对套管叉热锻工艺和模具的设计与优化以及套管叉热锻技术的发展具有重要的理论意义和实用价值。
本文对套管叉热成形过程三维刚粘塑性有限元模拟分析中关键技术问题进行了较深入的研究，建立了符合实际的套管叉热成形过程三维有限元模拟的力学模型，应用美国SFTC公司开发的DEFORM3D有限元模拟分析系统对套管叉热锻过程进行了系统的模拟分析。获得了该锻件不同变形阶段的变形体形状、变形坯料内网格图、速度场、等效应力、 等效应变、材料损伤等场变量的分布及成形过程载荷-行程曲线等结果。研究表明，套管叉热成形过程分为预成形和终成形两个工序，其中预成形为棒料局部镦粗工艺，变形体内各部分应力、应变的分布集中在预成形件头部，分布也不均匀，且坯料头部的变形较大，杆部的变形较小；终成形过程是叉部形成过程，变形坯料内的应力、应变、速度及损伤的分布随压下量不同而不同，基本分为三个阶段，并且在同一变形阶段内各主要场量的分布也不均匀。成形初期叉部底端圆角处的变形较大，应力、应变值也较大，叉部顶端的坯料流动速度较大，应力、应变值较小；成形后期叉部顶端区域的应力、应变值较大，同时损伤因子值也较大。
本文根据套管叉热成形的特点及规律，提出了三种终成形凸模结构：无约束台凸模、平面约束台凸模及弧形约束台凸模。利用DEFORM3D系统，模拟研究了不同终成形凸模结构对套管叉热成形影响的规律。研究表明：采用无约束台凸模生产出符合外形和尺寸要求的锻件最小需用Φ38×165㎜的棒料来成形；采用平面约束台凸模生产出符合外形和尺寸要求的锻件最小需用Φ38×158㎜的棒料成形；采用弧形面约束台凸模生产出符合要求的锻件最小需用Φ38×155㎜的棒料就能够满足。 另外，采用平面约束台凸模在热成形过程中会出现载荷突变，这将降低模具的使用寿命，而弧形面约束台凸模能够较好地克服这一问题，因而采用弧形面约束台凸模在套管叉终成形时能够得质量和尺寸较为理想的锻件，并且能够使初始坯料高度减少10mm，节约材料0.09Kg/件。另外，这种凸模所形成的顶部废料厚度为原来的1/2，切边所需的力减少1/2，切边模具的实际使用寿命至少提高为原来的2倍。
基于常摩擦模型，利用DEFORM3D系统，模拟研究了变形坯料与模具间的摩擦对套管叉热成形过程的影响。结果显示：坯料杆部的变形基本不受摩擦的影响。叉部各区域的变形随摩擦的不同差别也较大，总的说来当摩擦因子m值较大时，材料变
形的流动速度会降低，变形抗力会增大，变形所需载荷也较大，成形相对比较困难。否则，情况则刚好相反。因而，在生产过程中应尽量减小坯料与模具间的摩擦。
本文利用长安厂设备JS-630离合器式螺旋压力机及45钢为实验材料进行了生产实验，通过实验数据与模拟数据的对比，进一步验证了DEFORM3D有限元数值模拟系统的有效性和模拟结果的可靠性。
The transmission-shaft is one of the most important parts in the SC6350 car of Changan automobile liability co ltd. The transmission shaft belongs to longer shaft and furcated parts which shapes are complicated and metal flowing in forming process is difficult. Previously no thorough study has been carried out on this kind of parts and the configuration of die used for manufacturing has not been optimized. Therefore, systematically and through research on the deformation process of transmission shaft and on the optimization of it form law is very important for die design and its process analysis via 3-D FEM simulation. A brief introduction to the project and its main results are as follows:
A thorough study on the key technical problems of 3D rigid-viscoplastic FEM simulation of transmission-shaft hot forging process has been carried out and a 3D FEM simulation mechanics model corresponding to reality has been proposed. Simulation and analysis has been done using DEFORM3D developed by SFTC Corporation in USA. A series results such as the deformed mesh, velocity field, equivalent stress field, equivalent strain field, material damage and load stroke curve at various deformation degrees have been obtained. The research shows that its hot process consists of two working stages, which are preform and finish-form. On the process of preform, the distribution of stress and strain and local upsetting in top fields are largest and are extremely uneven; the deformation in the head is larger, and the deformation in the pole is smaller. On the process of finish-form, the deformation in the furcate fields is largest, the distribution of equivalent stress, equivalent strain, velocity and damage are different at various deformation degrees, which are divided into three phases and the distribution of the main variable are extremely uneven at same phase; the value of equivalent stress, equivalent strain and deformation are larger at bottom of the fork, at the same time, the values of equivalent stress, equivalent strain are smaller, but the velocity of deformation is larger on initial stage of forming. However, the values of equivalent stress, equivalent strain and damage are larger at furcate top on later period of deformation.
Based on the trait and law of hot deformation of transmission-shaft, three kinds of finish-form punch are designed: the punch without restricts, the punch with plane restricts and the punch with cambered restrict. A simulation and analysis has been
carried out by using DEFORM3D for hot deformation process of finish-form punch with different configuration. The research shows that, the dimension of billet at least is Φ38×165㎜ for eligible products that are produced by using the punch without restrict; the dimension of billet at least is Φ38×158㎜ for eligible products that are produced by using the punch with plane restrict; the dimension of billet at least is Φ38×155㎜ for eligible products that are produced by using the punch with cambered restrict. On the other side, the break of load occurs in hot deformation process when using the punch with plane restricts. This will reduce the die's natural life. However, the problem can be overcame and the eligible products can be obtained when using the punch with cambered restricts. Other, the billet height can be reduced 10mm and 0.09Kg material can be saved per work piece when using the punch with cambered restrict. Besides, the thickness of top scrap is reduced half, so that the life of the trimming die is increased at least two times in the followed procedure.
Based on the usual function frictional model, a simulation and study of an influence of friction along die-material interface on the hot deformation process of transmission-shaft has been carried out by using DEFORM3D. The results show: the deformation in billet pole is hardly affected by friction, but the deformation in fork field notably varies with various friction conditions. Taking one with another, the larger the friction factor, the metal flow reduced, the resistance and the loa
本文对套管叉热成形过程三维刚粘塑性有限元模拟分析中关键技术问题进行了较深入的研究，建立了符合实际的套管叉热成形过程三维有限元模拟的力学模型，应用美国SFTC公司开发的DEFORM3D有限元模拟分析系统对套管叉热锻过程进行了系统的模拟分析。获得了该锻件不同变形阶段的变形体形状、变形坯料内网格图、速度场、等效应力、 等效应变、材料损伤等场变量的分布及成形过程载荷-行程曲线等结果。研究表明，套管叉热成形过程分为预成形和终成形两个工序，其中预成形为棒料局部镦粗工艺，变形体内各部分应力、应变的分布集中在预成形件头部，分布也不均匀，且坯料头部的变形较大，杆部的变形较小；终成形过程是叉部形成过程，变形坯料内的应力、应变、速度及损伤的分布随压下量不同而不同，基本分为三个阶段，并且在同一变形阶段内各主要场量的分布也不均匀。成形初期叉部底端圆角处的变形较大，应力、应变值也较大，叉部顶端的坯料流动速度较大，应力、应变值较小；成形后期叉部顶端区域的应力、应变值较大，同时损伤因子值也较大。
本文根据套管叉热成形的特点及规律，提出了三种终成形凸模结构：无约束台凸模、平面约束台凸模及弧形约束台凸模。利用DEFORM3D系统，模拟研究了不同终成形凸模结构对套管叉热成形影响的规律。研究表明：采用无约束台凸模生产出符合外形和尺寸要求的锻件最小需用Φ38×165㎜的棒料来成形；采用平面约束台凸模生产出符合外形和尺寸要求的锻件最小需用Φ38×158㎜的棒料成形；采用弧形面约束台凸模生产出符合要求的锻件最小需用Φ38×155㎜的棒料就能够满足。 另外，采用平面约束台凸模在热成形过程中会出现载荷突变，这将降低模具的使用寿命，而弧形面约束台凸模能够较好地克服这一问题，因而采用弧形面约束台凸模在套管叉终成形时能够得质量和尺寸较为理想的锻件，并且能够使初始坯料高度减少10mm，节约材料0.09Kg/件。另外，这种凸模所形成的顶部废料厚度为原来的1/2，切边所需的力减少1/2，切边模具的实际使用寿命至少提高为原来的2倍。
基于常摩擦模型，利用DEFORM3D系统，模拟研究了变形坯料与模具间的摩擦对套管叉热成形过程的影响。结果显示：坯料杆部的变形基本不受摩擦的影响。叉部各区域的变形随摩擦的不同差别也较大，总的说来当摩擦因子m值较大时，材料变
形的流动速度会降低，变形抗力会增大，变形所需载荷也较大，成形相对比较困难。否则，情况则刚好相反。因而，在生产过程中应尽量减小坯料与模具间的摩擦。
本文利用长安厂设备JS-630离合器式螺旋压力机及45钢为实验材料进行了生产实验，通过实验数据与模拟数据的对比，进一步验证了DEFORM3D有限元数值模拟系统的有效性和模拟结果的可靠性。
The transmission-shaft is one of the most important parts in the SC6350 car of Changan automobile liability co ltd. The transmission shaft belongs to longer shaft and furcated parts which shapes are complicated and metal flowing in forming process is difficult. Previously no thorough study has been carried out on this kind of parts and the configuration of die used for manufacturing has not been optimized. Therefore, systematically and through research on the deformation process of transmission shaft and on the optimization of it form law is very important for die design and its process analysis via 3-D FEM simulation. A brief introduction to the project and its main results are as follows:
A thorough study on the key technical problems of 3D rigid-viscoplastic FEM simulation of transmission-shaft hot forging process has been carried out and a 3D FEM simulation mechanics model corresponding to reality has been proposed. Simulation and analysis has been done using DEFORM3D developed by SFTC Corporation in USA. A series results such as the deformed mesh, velocity field, equivalent stress field, equivalent strain field, material damage and load stroke curve at various deformation degrees have been obtained. The research shows that its hot process consists of two working stages, which are preform and finish-form. On the process of preform, the distribution of stress and strain and local upsetting in top fields are largest and are extremely uneven; the deformation in the head is larger, and the deformation in the pole is smaller. On the process of finish-form, the deformation in the furcate fields is largest, the distribution of equivalent stress, equivalent strain, velocity and damage are different at various deformation degrees, which are divided into three phases and the distribution of the main variable are extremely uneven at same phase; the value of equivalent stress, equivalent strain and deformation are larger at bottom of the fork, at the same time, the values of equivalent stress, equivalent strain are smaller, but the velocity of deformation is larger on initial stage of forming. However, the values of equivalent stress, equivalent strain and damage are larger at furcate top on later period of deformation.
Based on the trait and law of hot deformation of transmission-shaft, three kinds of finish-form punch are designed: the punch without restricts, the punch with plane restricts and the punch with cambered restrict. A simulation and analysis has been
carried out by using DEFORM3D for hot deformation process of finish-form punch with different configuration. The research shows that, the dimension of billet at least is Φ38×165㎜ for eligible products that are produced by using the punch without restrict; the dimension of billet at least is Φ38×158㎜ for eligible products that are produced by using the punch with plane restrict; the dimension of billet at least is Φ38×155㎜ for eligible products that are produced by using the punch with cambered restrict. On the other side, the break of load occurs in hot deformation process when using the punch with plane restricts. This will reduce the die's natural life. However, the problem can be overcame and the eligible products can be obtained when using the punch with cambered restricts. Other, the billet height can be reduced 10mm and 0.09Kg material can be saved per work piece when using the punch with cambered restrict. Besides, the thickness of top scrap is reduced half, so that the life of the trimming die is increased at least two times in the followed procedure.
Based on the usual function frictional model, a simulation and study of an influence of friction along die-material interface on the hot deformation process of transmission-shaft has been carried out by using DEFORM3D. The results show: the deformation in billet pole is hardly affected by friction, but the deformation in fork field notably varies with various friction conditions. Taking one with another, the larger the friction factor, the metal flow reduced, the resistance and the loa
引文
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[2] 汪大年. 金属塑性成形原理. 西安：西安交通大学，1986
[3] 王祖唐，关廷栋，肖景容等. 金属塑性成形理论. 北京：机械工业出版社，1989
[4] 吴诗惇. 挤压理论. 北京：国防工业出版社，1994
[5] 彭颖红. 金属塑性成形仿真技术. 上海：上海交通大学出版社，1999
[6] 李尚健. 金属塑性成形过程模拟.北京.机械工业出版社.1999
[7] 邝国能等. 工程实用边界单元法，北京：中国铁道出版社，1989
[8] 周杰等. 摩擦对收口的影响研究. 锻压技术, 2001, 26 (1)
[9] 周永强等. 万向节叉热成形过程模拟研究. 锻压技术, 2002, 2
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