|
|
Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2017 Vol.18 No.3 P.194-211
Study on the deformation theory of a parabolic part based on solid granules medium forming
Abstract: Solid granules medium forming (SGMF), a new flexible die forming technology, uses solid granules instead of a rigid male or female die (or elastomer, liquid) for sheet metal drawing. The good fluidity and compressive capacity of a solid granules medium can improve the forming limit of complex shell parts. The sheet metal drawing process of SGMF is a compound process of drawing and bulging, which is very different from the conventional drawing process. A parabolic part is used as the research object for a study of the forming process. Two concepts, drawing weight and bulging weight, are originally proposed in the sheet metal drawing of SGMF (replacing the rigid male die), and the corresponding expressions are obtained. The computational formulas of geometrical conditions and strain in the sheet metal drawing of SGMF are established, and the radius of the strain dividing circle is obtained by calculation. The established theoretical model is applied to the research object, an aircraft part, to analyze the forming process. The results show that the proposed theory can be applied to analyze the strain in different deformation regions of SGMF. This original theory provides a new theoretical analysis for studying the sheet metal drawing of SGMF.
Key words: Solid granules medium, Flexible die forming, Drawing, Drawing weight, Bulging weight, Strain
创新点：1. 首次提出了描述固体颗粒介质板材拉深成形变形机理的拉深权和胀形权的概念，并建立了相应的计算公式；2. 建立了固体颗粒介质抛物线型零件软凸模拉深成形的几何条件和应变计算公式。
方法：1. 通过对抛物线型零件固体颗粒介质拉深成形的变形过程分析(图1~3)，将变形过程和成形工件的变形区进行划分；2. 将数学中权函数的思想引入到对抛物线型零件固体颗粒介质拉深成形的分析中，提出拉深权和胀形权的定义及相应表达式(公式(1)和(2))；3. 通过理论推导，构建不同成形阶段抛物线型零件拉深成形过程中的应变计算式(公式(28)~(30)和公式(62a)~(62c))和壁厚计算公式(公式(31)和(63))；4. 利用MATLAB编制抛物线型零件拉深成形应变计算程序(图14)；5. 以某航空零件为目标零件，通过试验试制不同成形条件下不同阶段的抛物线型工件(表2和3)，将理论计算壁厚与实测厚度进行对比(图19)，将试验轮廓与理论计算轮廓进行对比(图21)，验证分析过程中所提假设及理论计算的可行性和正确性；将试验获得成形工件的几何尺寸(表3)代入MATLAB计算程序中，对该航空零件的变形过程进行分析(图15、18、19、21和22)。
结论：1. 固体颗粒介质拉深成形过程是胀形和拉深的复合成形，通过对其变形过程分析，首次提出了拉深权和胀形权的概念，并且给出了其计算公式。成形过程中，拉深权越大，工件成形后的壁厚差越小；胀形权则正好相反。2. 利用拉深权和胀形权，建立了固体颗粒介质软凸模拉深成形变形区应变计算公式，且可以计算出应变分界圆位置半径，为分析固体颗粒介质软凸模拉深成形工艺变形过程提供了新的理论依据。3. 设置合理的成形条件、拉深权的提高和应变分界圆半径的缩小可以降低拉深成形过程中底部的过度减薄，进而提高极限成形高度。
关键词组：
References:
Open peer comments: Debate/Discuss/Question/Opinion
<1>
DOI:
10.1631/jzus.A1600408
CLC number:
TG386
Download Full Text:
Downloaded:
2614
Download summary:
<Click Here>Downloaded:
1999Clicked:
4212
Cited:
0
On-line Access:
2017-03-07
Received:
2016-06-01
Revision Accepted:
2016-09-01
Crosschecked:
2017-02-07