曲面连续辊压成形中的辊缝控制及数值分析与实验研究

发布时间：2018-01-04 21:39

本文关键词：曲面连续辊压成形中的辊缝控制及数值分析与实验研究　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：曲面连续辊压成形是一种新型的板料连续成形工艺，将传统轧制技术与多点调形技术相结合，采用两个可小挠度弯曲的柔性辊作为工作辊。该方法的理论基础是不均匀减薄原理和横向弯曲变形机理。通过调形机构可调节柔性辊的横向弯曲和辊缝大小，从而实现不同曲率的三维曲面板类件的高效、连续成形，在汽车、飞机、船舶和建筑等领域有着广泛的应用前景。连续辊压成形的曲面形状是由辊缝控制的，在成形过程中，工作辊总成的弹性变形使辊缝发生变化，实际辊缝大小与目标辊缝发生偏离，成形件达不到目标形状。在工作辊总成内有一个柔性辊和两个钢丝软轴支撑辊，钢丝软轴的刚度小，弹性变形量大，钢丝软轴的弹性变形量是辊缝变化的主要原因。本文考虑了实际成形过程中钢丝软轴支撑辊的变形，建立了更贴合实际的有限元模型，采用数值分析方法对连续辊压成形中的辊缝变化及影响因素进行了研究；提出基于工作辊机构弹性变形补偿的辊缝修正方法，对辊缝修正方法进行数值分析和实验验证；对基于钢丝软轴支撑辊的辊缝控制方法进行改进，采用基于光轴支撑辊的辊缝控制方法，进行了数值分析和实验验证，并将两种辊缝控制方法进行了对比分析。本文的主要研究内容和结论如下：（1）研究了不同工艺参数对连续辊压成形中辊缝变化的影响。结果表明：随着板料压缩率的增大，辊缝相对变化量增大；板料强度越高，辊缝相对变化量越大；在相同整体下压量的条件下，随板料厚度减小，，辊缝相对变化量变大；在整体下压量相同的条件下，随着相邻两钢丝软轴间距离增大，辊缝相对变化量增大；随着上辊施加的整体下压量的增大，对辊缝的补偿增多，辊缝相对变化量逐渐减小。（2）研究了凸曲面和鞍面的辊缝变化规律。结果表明：成形凸曲面件时，辊缝中间部位的辊缝变化量大于辊缝边缘部位的辊缝变化量；成形鞍面件时，辊缝边缘部位的辊缝变化量大于辊缝中间部位的辊缝变化量。（3）将工作辊总成内各部分的弹性变形量进行对比，得出辊缝变化的主要原因。柔性辊弹性变形量很小，为10-4mm数量级，相对于钢丝软轴支撑辊弹性变形量和柔性辊中心与钢丝软轴支撑辊中心的竖直方向距离变化量可以近似忽略，钢丝软轴支撑辊弹性变形量、柔性辊中心与钢丝软轴支撑辊中心的竖直方向距离变化量是辊缝变化的主要原因。（4）提出了基于工作辊机构弹性变形补偿的辊缝修正方法，并进行了数值分析和实验验证。利用工作辊机构各部分弹性变形量之和作为第一次修正量，不同修正步的总弹性变形量差值作为后续修正步的修正量，对辊缝进行修正。通过数值分析和实验研究发现：修正后的辊缝变化量明显小于修正前，辊缝达到较高精度，成形件也达到较高的表面质量和成形精度。（5）对辊缝控制方法进行改进，采用基于光轴支撑辊的辊缝控制方法，并对基于光轴支撑辊的辊缝控制方法进行数值分析和实验研究。结果表明：采用基于光轴支撑辊的辊缝控制方法时，辊缝相对变化量明显减小，辊缝修正量和修正次数也明显减少。采用两种辊缝控制方法对辊缝进行若干次修正后，基于光轴支撑辊的辊缝控制方法采用更少的修正次数和更小的修正量，可以获得更高的成形精度，基于光轴支撑辊的辊缝控制方法明显优于基于钢丝软轴支撑辊的辊缝控制方法。
[Abstract]:The continuous roll forming process of curved surface is a new continuous forming process of sheet material . The traditional rolling technology is combined with multi - point adjustment technology . Two flexible rolls with small deflection are used as the working rolls . The theory basis of this method is uneven thinning principle and transverse bending deformation mechanism . The transverse bending and roll gap size of flexible roll can be adjusted by the adjusting mechanism , so that the three - dimensional curved surface plate with different curvature can be formed efficiently and continuously , and has wide application prospect in the fields of automobile , airplane , ship and building . the shape of the curved surface formed by the continuous rolling is controlled by a roller seam ; during the forming process , the elastic deformation of the working roller assembly causes the roller gap to change , the actual roll gap size is deviated from the target roll gap , the forming piece can not reach the target shape , and the working roll assembly has a flexible roller and two steel wire flexible shaft support rollers , the rigidity of the steel wire flexible shaft is small , the elastic deformation amount is large , and the elastic deformation amount of the steel wire flexible shaft is the main reason of the change of the roll gap . In this paper , the deformation of the steel wire flexible shaft supporting roller during the actual forming process is considered , and a more realistic finite element model is established . The roller gap correction method based on the elastic deformation compensation of the work roller mechanism is adopted to carry out numerical analysis and experimental verification on the roller gap control method based on the elastic deformation compensation of the work roller mechanism . The main research contents and conclusions are as follows : ( 1 ) The effect of different process parameters on the change of roll gap in continuous roll press forming is studied . The results show that the relative change of roll gap increases with the increase of the compression ratio of the sheet material , the higher the plate material strength , the greater the relative change of the roll gap , and the relative change amount of the roll gap decreases with the increase of the distance between the two adjacent steel wires under the same condition of the same overall depression amount . As the total downward pressure applied by the upper roll increases , the compensation of the roll gap increases , and the relative change amount of the roll gap decreases . ( 2 ) The variation law of roll gap between convex curved surface and saddle surface is studied . The results show that when forming convex curved surface piece , the change amount of roll gap in the middle part of roll gap is greater than the change amount of roll gap at the edge part of roll gap ; when forming saddle surface piece , the change amount of roll gap in the edge part of roll gap is greater than that of roll gap in middle part of roll gap . and ( 3 ) comparing the elastic deformation amount of each part in the working roll assembly to obtain the main reason of the change of the roll gap , wherein the elastic deformation amount of the flexible roller is very small , the distance variation of the elastic deformation amount of the flexible roller support roller and the center of the flexible roller center and the steel wire flexible shaft support roller can be approximately ignored , the elastic deformation amount of the steel wire flexible shaft support roller , and the change amount of the distance between the center of the flexible roller and the center of the steel wire flexible shaft support roller are the main causes of the change of the roll gap . ( 4 ) The roll gap correction method based on the elastic deformation compensation of the work roll mechanism is put forward , and the numerical analysis and experimental verification are carried out . By using the sum of the elastic deformation amount of each part of the working roller mechanism as the correction amount of the subsequent correction step , the roll gap is corrected . Through numerical analysis and experimental research , it is found that the modified roll gap change amount is obviously smaller than the correction , and the roll gap reaches higher precision , and the former also reaches higher surface quality and forming precision . ( 5 ) To improve the roll gap control method , a roll gap control method based on an optical axis support roller is adopted , and numerical analysis and experimental research on the roll gap control method based on the optical axis support roller are carried out . The results show that the roll gap control method based on the optical axis support roller is obviously reduced , and the roll gap control method based on the optical axis support roller can obtain higher forming precision , and the roll gap control method based on the optical axis support roller is obviously better than the roll gap control method based on the steel wire flexible shaft support roller .

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG306

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