基于Lemaitre模型的辊式冲裁工艺断面质量分析

为了准确表征材料变形中逐渐劣化的过程,引入考虑损伤与裂纹萌发的弹塑性本构模型.基于Abaqus/Explicit的二次开发接口,编写耦合Lemaitre损伤模型的用户子程序,根据算例验证其可靠性.通过反复加载-卸载拉伸试验并利用弹性模量变化法来获得损伤参数值.建立辊式冲裁工艺有限元模型,应用Lemaitre损伤模型来预测断面质量,并进行试验验证.分析冲裁间隙、模具磨损与板厚等工艺参数对断面质量、冲裁力及扭矩的影响.结果表明:前刃口断面质量总体上要好于后刃口,但光亮带具有一定的倾角;塌角区会随冲裁间隙增加而增大;模具磨损程度增加会导致毛刺急剧增大;最大冲裁力与扭矩会随着板厚的增大而增大.      

基于剪切修正GTN损伤模型的辊冲工艺数值模拟

在GTN模型基础上,考虑到微孔洞剪切变形对材料劣化的影响,建立适用于压应力状态的剪切修正模型.通过用户子程序接口VUMAT将与损伤耦合的弹塑性本构模型嵌入具有ALE法的有限元软件Abaqus/Explicit中.利用模拟拉伸与纯剪切试验拟合载荷-位移曲线以确定模型参数.将修正模型应用到辊冲工艺有限元模拟中预测断面质量,并进行试验验证.结果表明:前刃口为小间隙冲裁,塌角较小,光亮带较大但带有一定的倾角;后刃口为大间隙冲裁,塌角与断裂带较大,光亮带较小;裂纹会同时在前刃口凸模与凹模侧面萌发,而对于后刃口,会首先在凹模侧面产生.      

冷轧硅钢成品剪切机组纵切毛刺产生原因及处理办法

阐述了冷轧硅钢剪切机组纵切毛刺产生的原因,分析了剪刃侧隙、重叠量、剪刃精度和刃口状态和纵剪机的精度等因素对硅钢纵切毛刺的影响,提出了纵切毛刺超差的原因的处理办法：采用新型毛刺清理装置,使冷轧硅钢的成品毛刺控制在了0.01 mm以内,满足下游用户的要求,对提高剪切质量及成品率具有重要的参考价值。     

高强钢冲裁断面质量模具间隙敏感性分析

高强度汽车板应用越来越多,其成形边裂问题一直是研究的热点。冲裁间隙对冲压件断面质量有着重要的影响,以S550MC、S315MC和SPFH590等3种高强钢板为研究对象,以冲孔、扩孔和电镜扫描等物理试验为研究手段,分析了冲裁间隙对断面质量、冲裁力和扩孔率的影响。结果表明,对于高强钢来说,随着光亮带宽度的增加,扩孔率并不一定增加;对于S550MC来说,适当增加冲裁间隙不仅有利于降低冲裁力,且有利于提高板料的扩孔性能。     

基于电子图板快速确定冲裁模压力中心

在冲模设计中,冲裁模压力中心通常采用计算法、作图法或悬挂法求解,其计算量大,操作繁琐,且容易出错.为简化计算过程,通过CAXA电子图板的偏移命令将冲裁轮廓转化为无限小的面域,使用了桥接方式使面域重心确定简单化,提出了基于电子图板快速确定压力中心的方法,实现了多凸模冲裁模压力中心的精确计算.计算结果表明,此方法在冲压工艺计算中值得推广.     

B1500 HS硼钢热冲裁过程的相变和冲裁精度

为了研究热冲裁零件微观组织及尺寸精度的变化规律,采用不同的冲裁温度和模具间隙比对B1500HS钢板进行了热冲裁试验.根据冷却曲线,研究了冲裁温度对硼钢组织转变和零件力学性能的影响;根据落料件的尺寸,分析了冲裁温度和模具间隙比对尺寸精度的影响;通过观察零件的断口形貌,分析了冲裁温度对断口质量的影响.结果表明:当冲裁温度一定时,落料件的尺寸随着模具间隙比的减小而增大;当模具间隙比一定时,落料件的尺寸误差随着冲裁温度的降低出现“正—负—正”的增长波动趋势;当冲裁温度为600~650℃或750~800℃时,落料件具有较高的冲裁精度;落料件的硬度随着冲裁温度的升高而增大,当冲裁温度为650~800℃时,落料件的组织为马氏体,硬度值HV约为550;冲裁断面光亮带的宽度随着冲裁温度升高而增大.      

基于ABAQUS的板材精冲工艺研究

构建厚度为1.5mm的板材精密冲裁有限元模型,分析板材精冲的变形过程.通过大量有限元模拟,重点分析压边力和反压力对精冲断面质量的影响规律,并将模拟结果和试验结果进行对比分析.结果表明:当压边力不变时,随着反压力的增大,精冲断裂带长度不断减小,而断面平整度逐渐变差;当反压力不变时,断裂带长度不随压边力的增大发生较大改变,但断面平整度提高;当压边力和反压力相互配合时,冲孔断裂带最小,断面平整度最好;模拟结果与试验结果非常接近,说明压边力对精冲断面质量影响规律的模拟结果准确.     

一种板材小圆角胀压复合成形工艺解析

针对薄壁板材零件小圆角特征成形制造难的问题,提出了一种新型胀压复合成形工艺.其关键工艺参数为:预成形高度、预成形凹圆角大小和终成形胀形压力与背压凸模运行速度匹配关系.预成形高度决定了终成形小圆角的材料储备,预成形凹圆角的最佳值为充液拉深时凸模圆角可取的最小值,通过理论分析给出了预成形高度和预成形凹圆角的计算方法.建立了胀压复合成形过程力学模型,通过应力状态分析给出了不同胀形压力与背压凸模运行速度匹配关系下坯料圆角区变形状况.同时基于有限元模拟和工艺试验,研究了预成形高度和终成形胀形压力与背压匹配路径对试验件成形质量的影响,验证了理论分析的准确性,并证明了该新工艺的适用性.      

超级钢板材V型弯曲回弹的数值模拟

利用ANSYS/LS-DYNA非线性动力有限元程序的显式-隐式连续求解功能,模拟了超级钢板材在弯曲成形和卸载后的回弹变形过程,得到了超级钢板材在不同凸模圆角半径下弯曲成形后的回弹结果.将模拟计算结果与实验结果进行对比,验证了计算结果的准确性.     

剪力墙大钢模施工中的门洞侧模板加固技术

在某工程施工中,针对剪力墙门洞尺寸较大、数量较多给施工带来的问题,对剪力墙侧模板的加固方式进行了改进.通过对支撑方案进行优化设计,解决了传统支模方式导致模板位移、变形及炸模的问题,保证了剪力墙的垂直度和平整度.结合该工程实例,介绍了剪力墙大门洞侧模的加固技术.     

Rotary Blanking ‐ a New Manufacturing Process

Rotary blanking is a method of blanking and punching with rotating tools whereby the cutting tools are fixed to a pair of rollers performing a continuous blanking operation on a strip of sheet metal. The purpose of this paper is to outline the determining conditions under which the rotary blanking process takes place and to discuss advantages, restrictions, applications and optimization of this technology.     

Asymmetric three-roller sheet-bending systems in steel-pipe production

Various attachments are used to produce components of particular configurations from metal sheet. In particular, sheet-bending roller systems may be classified in terms of the number of rollers (two, three, or four); the type of drive (mechanical, pneumatic, electromechanical, hydraulic); and the roller configuration (symmetric, asymmetric). Three-roller systems are used for the production of cylindrical, oval, and conical components by bending the metal sheet. They may be employed to manufacture pipes, channels, airways, shells, barrels, and sheathes. The operation of three-roller sheet-bending systems is based on the rotation of rollers in opposite directions, so that the sheet is captured and bent to the specified radius. To facilitate sheet supply and the release of the products bent into closed circles, the three-roller sheet-bending systems are combined with a removable front shaft applying a pressure that may be adjusted. In the three-roller systems, the diameter of the upper roller is about 1.5 times that of the lower rollers. In shaping, the rollers perform reversible motion. The upper roller may be raised and lowered to regulate the diameter of the circle produced. In this approach, extremely small sheet sections remain flat. This problem is eliminated by bending the ends of the sheet in a press or in a roller mill. In the present work, a mathematical method is proposed for determining the forces and torques in cold flexure of thick steel sheet on three-roller sheet-bending systems. The calculations permit the determination of the reaction of the roller supports, the residual stress in the wall of the steel sheet, the proportion of the plastic deformation over the sheet thickness, and the relative deformation of longitudinal surface fibers of the sheet in flexure as a function of the roller radius, the roller spacing, the reduction of the sheet by the upper roller, the sheet thickness, the Young’s modulus, the yield point, and the strengthening modulus of the steel sheet. The results may be used at metallurgical and manufacturing plants in the production of large-diameter steel pipe for major pipelines.     

中厚板热处理表面质量缺陷分析与控制

对热处理易出现的丸料压入、钢板下表面炉底辊压痕和钢板边部挤压变形等质量缺陷进行原因分析。通过对抛丸机组改造,在抛丸机上表面增加刮板和吹扫装置,改造下表面抛丸辊道;采用专用的钢板进行洗炉,清理黏附在炉底辊道表面的氧化铁皮;优化装炉制度和工艺参数,制定装炉偏移控制等措施,有效控制热处理钢板的表面质量。钢板热处理质量得到明显改善,提高了产品质量的控制能力。     

Causes of progressive stamping die damage and retooling measures to reduce carbide punch fracture

We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts.The failure modes of the carbide punches were statistically classified.Edge chipping and shoulder fracturing were the two types of failure modes that were found.The composition,hardness,and microstructure of the punches were analyzed.The cobalt content was found to be too low to ensure sufficient toughness.The brittle phase of tungsten carbide(WC) was prone to breaking off during the shear cutting process,and resulted in edge chipping.In addition,the material chips were easily bonded to the punch edge when there was a lack of press oil lubricity.It resulted in an uneven blanking clearance,which caused a lateral force and finally resulted in shoulder fracturing of the punches.Improvement measures were introduced to address the abovementioned issues.By using the carbide punches with greater toughness and shear cutting oil with high lubricity,the early damage problems of the punches are effectively solved,which ensures normal production of the magnetic shielding steel parts.     

圆盘剪切边过程间隙量与重叠量综合优化技术

 针对带钢切边过程现场与下游客户缺少统一的切边质量评价标准的问题,结合圆盘剪的设备与剪切工艺特点,经过大量现场试验与理论研究,在分析了带钢切边过程所存在的扣边、毛刺、切断比失衡三大主要质量缺陷的基础上,提出了一套有效实用的带钢切边质量评价方法。将带钢切边综合质量评价函数作为目标函数,圆盘剪间隙量与重叠量作为优化变量,开发出一套圆盘剪切边过程间隙量与重叠量综合优化设定的技术,并将其应用到某钢厂1 420生产线,大大提高了带钢切边质量,扣边、毛刺和切断比失衡缺陷改判率从技术应用前的0.52%下降到0.03%,同时保障了无返修,为企业创造了较大的经济效益,具有进一步推广应用的价值。     

滚切式双边剪剪刃间隙平行度偏差分析

双边剪剪刃的间隙与钢板厚度关系直接决定剪切钢板边部质量的好坏,文章主要分析剪刃间隙的平行度的不一致对钢板边部质量的影响,提出在生产过程中采取的处理方法和预防措施。