Influences of material parameters on deep drawing of thin-walled hemispheric surface part

During deep drawing process,the material parameters of blank have a significant effect on the quality of the drawn part and the determination of process parameters. Here,a 3D finite element model is developed for the deep drawing process of a thin-walled hemispheric surface part. Then the influences of material parameters including hardening exponent n,yield stress σs and elastic modulus E on the process are investigated by simulation. The results show that the effects of n and σs on punch force,thickness variation and equivalent strain are more notable. The maximum equivalent plastic strain occurs outside the die corner. However,when the value of n is 0.03 or σs is smaller than 120 MPa,higher equivalent plastic strain occurs at ball top.

FRACTURE LIMIT LOAD OF CONE SHAPE PART IN DRAWING PROCESS

The deformation characters and load status of the blank＇s potential fracture zone are analyzed at the moment when blank is approaching to punch comer in drawing process of cone shape part. Based on tension instability theory, the formula for calculating fracture limit load of cone shape part in drawing process is derived. Also, the formula is analyzed and verified by experiment.

Labeling Line Drawings with Hidden-Part-Drawn of Planar Object with Trihedral Vertices

Although line drawings consist of only line segments on a plane, they convey much information about the three-dimensional object structures. For a computer interpreting line drawings, some intelligent mechanism is required to extract three-dimensional information from the two-dimensional line drawings. In this paper, a new labeling theory and method are proposed for the two-dimensional line drawing with hidden-part-draw of a three-dimensional planar object with trihedral vertices. Some rules for labeling line drawing are established. There are 24 kinds of possible junctions for line drawing with hidden-part-draw, in which there are 8 possible Y and 16 W junctions. The three problems are solved that Sugihara＇s line drawing labeling technique exists. By analyzing the projections of the holes in manifold planar object, we have put forward a labeling method for the line drawing. Our labeling theory and method can discriminate between correct and incorrect hidden-part-draw natural line drawings. The hidden-part-draw natural line drawings can be labeled correctly by our labeling theory and method, whereas the labeling theory of Sugihara can only label the hidden-part-draw unnatural line drawings in which some visible lines must be drawn as hidden lines, and some invisible lines must be drawn as continuous lines.

NUMERICAL SIMULATION AND EXPERIMENTAL RESEARCH ON HYDRAULIC COUNTER-PRESSURE DEEP DRAWING OF CONICAL PART

Hydraulic counter pressure deep drawing of truncated conical part is numerically simulated with MARK and the nature of increasing the forming limit in this process is searched.The effects of blank holding force and chamber pressure on forming results are investigated by experiments and,as a result,truncated conical parts with large drawing ratio are successfully formed in single step with this drawing method.

Intelligent control technology for deep drawing of sheet metal

The intelligent press forming of sheet metal is a completely new and comprehensive technology that combines control-science, computer science, material science and metal forming theory. Although the technology originated in 1980s from America, it was focused on the spring-back of V-shaped bending. Not until 1990s was some pioneering research conducted on the intellectualized control of cup-deep drawing. The research field is expanded to the axis-symmetric part and non-axis symmetric part. After a series of theoretical and experimental research, an intellectualized control system on the deep drawing processing of sheet metal is developed. The common general feature of sheet metal on the process of deep drawing is analyzed and a completely mechanical model is concluded and the deep drawing intellectualized control of sheet metal is finally realized.

Research on friction law in deep drawing process of rectangular parts

Friction law is researched in rectangular parts deep drawing using simulation test ma-chine that is used to assess lubricants performance in deep drawing process. Friction coefficientsin different positions on die surface in deep drawing process are measured through probe sensors.Friction coefficients of flange corner, near straight border and far straight border are verified anddescribed quantitatively. It plays an important role in using appropriate lubricants in auto-bodypanel deep drawing process.

基于稀疏匹配的机床零件瑕疵投影辅助视觉检测方法

机械臂在自动精准打磨机床零件前需要对机床零件进行特征识别,传统激光点阵扫描精度高,但设备成本高昂而难以规模应用。引入固定式投影产生扫描线图、棋盘格图和随机灰度图等特征作为测量辅助,并结合双目立体视觉测量对零件瑕疵进行检测,改善了传统双目视觉针对光滑平面零件难以识别特征进行立体匹配的情况。分析结果与激光点阵扫描结果进行精度校验。同时,通过5种经典局部立体匹配算法与所提方法进行精度比较,并对辅助图的关键参数进行精度关联分析。最后,引入自适应算法对所提方法进行优化以提高识别精度。结果表明:随机灰度图能够显著提高匹配精度,扫描线优化与子像素拟合能够进一步提高匹配精度,扫描线法与棋盘格法优化后精度提高较大,新方法可有效识别平面零件的瑕疵特征,检测精度达标区域占比大于98%。

U型框类零件双向拉深成形研究

针对U型框类零件成形质量不稳定、修整手工量大等问题,通过对零件结构的分析研究,借助CATIA对其进行了工艺补充面设计,并借助数值模拟对成形过程进行了仿真,研究了双向拉深成形工艺,设计了一种特有传力方式的双向拉深模具结构;选取凸凹模间隙、摩擦因数、压边力及拉深速度4个因素为优化变量,通过正交试验得出最优工艺参数组合,即压边力大小为30 kN、摩擦因数为0.1、凸凹模间隙为1.6 mm、拉深速度为6000 mm·s^(-1);最后针对拉深后回弹现象,对校正模进行了分析和设计并修整。生产试验表明,此模具结构可以很好地改善零件成形质量,提高效率并满足生产及设计要求。

Inner wrinkling control in hydrodynamic deep drawing of an irregular surface part using drawbeads

Inner wrinkling phenomenon is more likely to develop during hydrodynamic deep drawing （HDD） of complicated component-forms due to the higher demand for controlling deformation sequences. Aiming at the problems in control of inner wrinkling for an irregular surface part featured with both concavity and convex, this research proposes an optimal design method of drawbead parameters to change the material flow. According to theoretical analysis of the mechanism of inner wrinkling, optimizing cavity pressure only is unreasonable to form a wrinkle-free deep-drawn part, so semi-circular drawbeads are employed. The effects of layout and height of drawbeads on forming results are discussed, and a process window is established based on evaluation indicators including the anti-wrinkle coefficient and the minimum wall thickness. Experiments are carried out to validate the process window, and the wall thickness and the wrinkle height are measured and compared with numerical findings. The results show that the anti-wrinkle ability of drawbeads weakens with increasing oblique angle and distance from the die center, while the wall thickness increases with increasing oblique angle and distance, and the inner wrinkling can be completely suppressed by drawbeads arranged in zones I and II with optimum penetration.

基于Towedm数控线切割编程系统的上下异形零件加工

分析了上下异形零件的线切割加工原理,基于Towedm数控线切割编程系统介绍上下异形零件的编程与加工的方法.基于DK7720电火花数控线切割机床的Towedm数控线切割编程系统,以上表面为圆和下表面为正六边形复合的典型上下异形零件加工任务为例,对其进行绘图编程、生成加工轨迹和3B格式的数控程序以及进行线切割加工和分析.

拉深模间隙对薄壁件壁厚的影响规律研究

薄壁零件利用拉深模具成形,拉深件可加工尺寸范围相当广泛。利用拉深模具成形,产品具有一致性,故拉深工艺可高效生产,使材料得到充分利用。本文通过有限元分析软件模拟分析局部热等静压的拉深成形过程效果;在此基础上模拟分析锥部两次拉深成形过程中不同参数方案下的壁厚演变规律,并基于此优化参数方案,实现对薄壁零件拉深成形的壁厚控制。

基于特征关联的零件图尺寸自动标注方法

三维模型生成二维零件图后,存在多视图尺寸标注繁琐、尺寸表达不规范等问题,为确保零件图尺寸标注的完整性,提出了一种基于特征关联的零件图尺寸自动标注算法。首先,建立特征封装体的参数化建模方法,分析零件特征关联关系;其次,创建“修饰特征-特征关联-尺寸”的关联机制获取特征尺寸,并结合尺寸完备性处理方法完成零件图多视图尺寸自动标注。将该算法无缝集成到Creo软件平台上,开发一套零件图尺寸自动标注系统。最后,在Creo平台通过实例测试,验证了所提方法的有效性和可行性。

基于中望ZW3D和ZWCAD软件的轴套类零件工程图绘制

职业院校技能大赛背景下,数字化设计与制造赛项对零件工程图提出了更高的要求。综合利用ZW3D和ZWCAD绘制工程图能大大提高作图效率,并且符合国家标准。本文首先阐述了轴套类零件的工程图表达方案,结合输出轴零件,深入分析了基于ZW3D和ZWCAD软件的工程图绘制流程、方法和步骤,快速高效完成符合国家制图标准的工程图绘制。

成形系列化不同长度零件可柔性化调整的模具结构设计

针对不同长度系列的接水盘,如采用1种规格用1副模具成形的方式,经济性差,对不同长度系列接水盘拉深成形特点进行分析,找出系列化接水盘拉深成形的共性点,根据共性点采用系列化分段柔性组合的方式进行切断与拉深,局部根据拉深成形的特点进行叠加,解决了系列化接水盘宽度相同而长度不同的成形问题。

基于FLD成形极限理论的盒型冲压件质量控制的研究

为研究复杂盒形件成型质量的控制,使用USIBOR1500高强钢,通过SIS系统建立了盒形件有限元模型,对冲压过程进行了仿真模拟,通过在压料板上添加拉延筋结构对比成形结果,分析拉延筋对盒形件冲压成形的影响。仿真结果表明,通过增加拉延筋可以改变材料流动,减少拉延过程中材料起皱的程度。同时,提取了冲压成形过程中的行程曲线,确定拉延过程所需成形力和压边力大小,为模具设计提供依据,也可为其他同类冲压制件的成形提供参考。

中职汽车机械零部件制图人才培养方向的探索

中职汽车机械零部件制图人才是汽车机械制造业中不可或缺的重要力量,而其培养方向对于行业的发展和人才引领的作用显得至关重要。本文以此为研究对象,探索中职汽车机械零部件制图人才培养的方向。首先,通过调查和分析当前行业技术发展趋势以及市场需求,从制图技能、制图知识、实践技能和高素质人才四个方面提出了人才培养的主要方向和目标。其次,分析中职教育条件和实践教学的具体要求,提出了校企合作、开设实践课程、开展实习和实训等措施,以培养适应市场需求的中职汽车机械零部件制图人才。

长环形薄壁唇口整体充液成形方法研究

针对大拉深比长环形薄壁唇口难成形问题,设计了先成形气动外形区,后成形内侧进气道区的二次被动充液成形工艺方案。借助有限元模型分析并结合试模优化实现了长环形薄壁唇口整体成形,通过模拟优化液压室加载曲线、压边条件、反胀、坯料形状等了解壁厚变化规律,液压室压力使板料与凸模之间产生有益摩擦,可抑制凸模圆角处的减薄;在定间隙压边条件下,法兰根部悬空区减薄率随着最大液压室压力的增大而增大。与传统拉深比较,被动充液成形易将最大减薄区由凸模圆角区转移至凹模圆角区。

基于3种驱动方式的镁合金覆盖件柔性砂模拉深试验与仿真研究

选择砂子作为柔性介质,通过砂子摆放位置的不同实现不同驱动方式,并针对复杂镁合金覆盖件进行研究。采用有限元模拟与拉深试验对比验证的方法,针对差异化驱动方式探究了拉深温度、板厚以及填砂高度对镁合金板材成形结果的影响,并采用宏微观协同验证的方法对有限元模拟进行验证。针对复杂镁合金覆盖件,最终提出了能够改善其拉深性能的优化策略。

盒形件拉伸次数的快速确定方法

介绍了盒形件拉伸成形特点,分析了高低盒形件的界定及盒形件拉伸次数的快速确定。

基于AutoForm-PD软件DL图全参数化建型研究

冲压工艺DL图的设计过程复杂,方案多变,不仅型面需要根据模拟结果进行更改,修边工序也需要根据结构空间和强度等因素进行多次变更,这就导致需要经过不断的更改和尝试,才能得到稳定的DL图。AutoForm-PD是基于CATIA软件开发的冲压工艺建型软件,可以借助CATIA平台实现全工序全参数化的建型过程。利用AutoForm-PD软件建立了DL图设计模板,提出了整体规划工艺方案、分段建型的思路,有效的减少了因工艺方案更改而造成的DL图更改时间,使DL图设计效率提升100%以上。