共查询到18条相似文献,搜索用时 125 毫秒
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为实现21-6-9高强不锈钢管数控弯曲精确成形,提高其成形质量与成形极限,需要对弯曲过程中壁厚减薄进行有效控制。基于ABAQUS/Explicit有限元软件平台,建立了21-6-9高强不锈钢管数控弯曲三维弹塑性有限元模型,并对其可靠性进行了验证。通过有限元模拟和正交试验,研究了工艺参数对21-6-9高强不锈钢管数控弯曲壁厚减薄影响的显著性及规律。结果表明,影响壁厚减薄的显著性工艺参数依次为芯棒伸出量、管材与芯棒间隙、管材与防皱块摩擦因数、管材与芯棒摩擦因数、管材与压块摩擦因数和弯曲速度,其影响规律为:壁厚减薄率随着芯棒伸出量、管材与防皱块摩擦因数、管材与芯棒摩擦因数、管材与压块摩擦因数、弯曲速度的增大或管材与芯棒间隙的减小而增大。采用多元线性回归方法建立了最大壁厚减薄率与显著性工艺参数之间的回归预测模型,经对比验证,回归预测模型结果与正交试验结果之间的相对误差不超过5%。 相似文献
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薄壁管数控弯曲应变的网格法研究 总被引:4,自引:1,他引:4
采用网格法,对50mm×1mm×R100mm(管径×壁厚×弯曲半径)的LF2M和1Cr18Ni9Ti薄壁管数控弯曲中弯管三向应变分布规律进行了研究,结果表明:LF2M弯管最外侧切向拉应变大于1Cr18Ni9Ti弯管的最外侧切向拉应变,而最内侧压应变前者小于后者,导致与1Cr18Ni9Ti弯管相比,LF2M弯管的最外侧壁厚减薄应变大,最内侧增厚应变小;薄壁管小弯曲半径数控弯曲成形中,周向应变不可忽略,其值最大可达最大切向应变的1/3;随着弯曲角度的增大,弯管三向应变均增大,但周向应变增幅小于切向应变与厚向应变的增幅;LF2M弯管切向最外侧拉应变大于其最内侧压应变,1Cr18Ni9Ti弯管切向拉、压应变相差不大,导致前者最外侧壁厚减薄应变大于其最内侧增厚应变,而后者的壁厚减薄应变与增厚应变相差不大。 相似文献
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大口径船用管件多采用冷弯成形工艺,为掌握管件弯曲工艺参数对截面质量的影响规律,采用ABAQUS对管件弯曲过程进行模拟。模拟结果显示:随着芯棒与管件单侧间隙的增加,壁厚减薄率相应减小,单侧间隙合适范围为0.5mm~1mm;随着芯棒伸出量增加,弯管截面圆度值增大,芯棒伸出量合适范围为25mm~30mm。 相似文献
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《流体传动与控制》2016,(2)
以液压管路系统常用的20号冷拔无缝钢管为研究对象,基于ABAQUS软件建立其数控弯管过程有限元模型,模拟弯曲,抽芯,回弹三过程,分析应力应变分布规律,揭示弯管成形与回弹机理。研究结果与实际数控弯管生产过程的经验状况基本一致:在弯管过程,各区域切向应力应变先达最大值,而后应力大幅卸载但应变不变,完成塑性变形后该区域应力基本恒定,在后续弯管进程起传递弯矩作用;但初始弯曲区域受芯棒、模具影响,应力不卸载;抽芯、回弹对应力有卸载作用,对应变影响极小;回弹是钢管在残余应力作用下静力平衡过程,影响其成形,结束后存在残余应力。该研究有助于对弯管的成形、回弹机理的理解,为后续分析工艺参数对弯管成形质量的影响提供理论依据。 相似文献
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Double?roller clamping spinning(DRCS) is a new process for forming a thin?walled cylinder with a complex surface flange. The process requires a small spinning force,and can visibly improve forming quality and production e ciency. However,the deformation mechanism of the process has not been completely understood. Therefore,both a finite element numerical simulation and experimental research on the DRCS process are carried out. The results show that both radial force and axial force dominate the forming process of DRCS. The deformation area elongates along the radial direction and bends along the axial direction under the action of the two forces. Both the outer edge and round corner of the flange show the tangential tensile stress and radial compressive stress. The middle region shows tensile tangential stress and radial stress,while the inner edge shows compressive tangential stress and radial stress. Tan?gential tensile strain causes a wall thickness reduction in the outer edge and middle regions of the flange. The large compressive thickness strain causes material accumulation and thus,an increase in the wall thickness of the round corner. Because of bending deformation,the round corner shows a large radial tensile strain in addition. The inner edge of the flange shows small radial compressive strain and tensile strain in thickness. Thus,the wall thickness on the inner edge of the flange continues to increase,although the increment is small. Furthermore,microstructure analysis and tensile test results show that the flanged thin?walled cylinder formed by DRCS has good mechanical properties. The results provide instructions for the application of the DRCS process. 相似文献
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H. Li H. Yang K. Liu 《The International Journal of Advanced Manufacturing Technology》2013,65(9-12):1303-1318
Bent tubular parts have attracted extensive applications in various industries due to high strength and light weight. However, tube bending (TB) is a strong knowledge-based tri-nonlinear physical process with multi-tool constrains, and minor inappropriate tooling design may induce several failures such as wrinkling, over thinning (even fracture), section distortion, and springback. In response to the urgent requirements of the tubular products with mass quantities and diverse specifications, we proposed an integrated methodology for robust and loop tooling design for TB by combining several technologies such as knowledge-based engineering, parametric CAD modeling, and parametric finite element modeling. Via the spreadsheet formatted rules extracted from different sources of knowledge, several sequences are automatically conducted to preliminarily avoid the wrinkling and section distortion, including the selection of tooling sets (bend die, clamp die, pressure die, wiper die, or mandrel die with flexible balls), the determination of die dimensions, 3D modeling of both external and internal tools, die assemble, and the selection of material type for each die. Then, by importing the feature parameters of tools into 3D-finite elements models, the bendability of tube under previously designed multi-tool constraints is quantitatively evaluated in terms of multi-defect, and the springback can be calculated to redesign the bending die by radius reduction. The design variables are only tube diameter, wall thickness, bending radius, bending angle, and material types. The tool design system is then implemented, and the reliability and efficiency of the system are experimentally verified in the aviation industries regarding several practical bending cases with different specifications and tubular materials. 相似文献
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Mei Zhan Tao Huang Zhi-Qiang Jiang Pei-Pei Zhang He Yang 《The International Journal of Advanced Manufacturing Technology》2013,68(1-4):663-672
Determining appropriate process parameters is key to obtain qualified TA18 (Ti–3Al–2.5V, ASTM Gr. 9) titanium alloy tubes with medium strength by numerically controlled (NC) bending at low cost. This paper focuses on the variations in wall thickness and cross-section under various operating parameters and mandrel parameters for the NC bending of TA18 tubes. We put forward a method for quickly determining the range of the axial mandrel feed. The method is based on the principle of an equivalent mandrel supporting radius for a given bending radius but employing some mandrels with varying diameters and the principle of an equivalent mandrel supporting angle for various bending radii but employing the same diameter mandrel. The finite element analysis and the experimental verification results show that the bending speed should be less than 0.5 rad/s and the pressure die velocity should be approximately equal to or slightly higher than the bending speed, and that the method for determining the range of the axial mandrel feed is feasible. Considering the effects of an equivalent mandrel supporting radius and equivalent mandrel supporting angle, the mandrel diameter and axial feed should be chosen in a compatible range. 相似文献
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Yuanhai Xiao Yuli Liu He Yang Jiahai Ren 《The International Journal of Advanced Manufacturing Technology》2014,70(9-12):2003-2011
The rotary draw bending of double-ridged rectangular tube is a complex nonlinear physical process with multifactors coupling effects. Processing parameters, especially clearances and friction coefficients between tube and various dies, have a significant effect on the forming quality of the double-ridged rectangular tube in rotary draw bending. If the values of these processing parameters are inappropriate, some defects including cross-sectional deformation, wall thinning, and wall thickening easily occur in the bending process of double-ridged rectangular tube. So optimization of these processing parameters is of great importance to control these defects. Based on the grey relational analysis method combined with the orthogonal experimental design and finite element simulation, a grey relational analysis model was established for the rotary draw bending process of double-ridged rectangular H96 brass tube. With the model, optimization of clearances and friction coefficients between tube and various dies was implemented with consideration of interactive effects of the above defects. The results show that (1) the main factors influencing cross-sectional deformation, wall thickening, and wall thinning are tube–mandrel clearance Δc m, tube-bending die clearance Δc b, and tube–mandrel clearance Δc m, respectively. (2) The optimal values of clearances Δc m, Δc p, Δc w, and Δc b and friction coefficients μm, μp, μw, and μb of tube–mandrel, tube–pressure die, tube–wiper die, and tube-bending die are 0.15, 0.2, 0.2, 0.2, 0.02, 0.3, 0.06 and 0.17 mm, respectively. Furthermore, the verification for the optimal values of these processing parameters was carried out, and the double-ridged rectangular H96 bent tube obtained by using the optimal values of these processing parameters has the minimum values of cross-sectional deformation, wall thinning, and wall thickening and can satisfy the national aviation industry standards. 相似文献
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Huawen Shen Yuli Liu Haiyan Qi He Yang Shuhui Zhou 《The International Journal of Advanced Manufacturing Technology》2013,68(1-4):651-662
The significant cross-sectional distortion is one of the major problems in the bending of thin-walled rectangular waveguide tube. The cross-sectional distortion, which contains the flange distortion and the web distortion, depends on the stress components distribution. In this paper, the cross-sectional distortion characteristics are investigated using a three-dimensional finite element (FE) model. Results show that: the maximum flange distortion locates at the symmetric line; meanwhile, the maximum web distortion locates at the extrados ridge of the tube. The deformation zone of the tube can be divided into three sub-zones considering the loads and deformation, viz., the clamp die affect zone, the middle zone, and the mandrel/cores affect zone. Then the underlying relations between the cross-sectional distortion and the stress components are obtained. It is found that the flange distortion has a close relation with the circumferential stress. At the same time, the web distortion is relevant to both the tangential and the circumferential stress. The above relations are verified by FE models with different cores number. Moreover, some guidelines are introduced to help reduce the cross-sectional distortion. 相似文献
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Yuanhai Xiao Yuli Liu He Yang 《The International Journal of Advanced Manufacturing Technology》2014,73(9-12):1789-1798
Based on the ABAQUS/Explicit, a three-dimensional elastic–plastic finite element model of the H96 brass double-ridged rectangular tube (DRRT) during H-typed rotary draw bending (RDB) was established and its reliability was validated by an experiment. With the model, distribution characteristic of cross-sectional deformation and effects of clearance and friction coefficient between tube and dies and core number on it were studied. The results show that the maximum cross-sectional height distortion ratio appears at the bending angle 60°. And the maximum cross-sectional width distortion ratio between side walls, as well as side walls of the ridge grooves, appears at the bending angle 80° and 60°, respectively. In addition, retracting mandrel has a great effect on the cross-sectional height distortion, but its influence on the cross-sectional width distortion can be ignored. And the maximum cross-sectional distortion ratio initially increases with increasing of clearance between tube and mandrel c m and friction coefficient μ b between tube and bending die, and then decreases with their increase, and initially decreases with the increase of core number N, and then increases with increasing of N. Moreover, the reasonable value of N is taken as 4. 相似文献