Effect of Variable Blank Holder Force on Rectangular Box Drawing Process of Hot-galvanized Sheet Steel

At first, a series of finite element method （FEM） simulation tests were used to find the critical forming conditions of hot-galvanized sheet steel during the rectangular box drawing processing when constant blank holder forces were applied. According the test results, the reasonable alteration scope of initial variable blank holder force （VBHF） was as 1.9-2.3 T. Then, based on the test productions of blank holder force, 12 typical VBHF curves were applied to perform the simulation tests by the simulation software of DYNAFORM. The simulation test results showed that VBHF had great effects on drawing formability of hot-galvanized sheet steel during the rectangular box drawing. However, the different VBHF curves were applied to control the whole drawing and it would get great different effects. At the same tine, the VBHF had great effects on the maximum thick thinning ratio, but had little effect on the maximum thick incrassation ratio. So, reasonable application of the VBHF would greatly decrease the fractures. When the VBHF profile is taken as curve L, the best effect of drawing formability could be obtained. When curve I is used, contrary effect could be gotten. The other types of curves would cause effects between above two types of VBHF curves. Finally, the actual tests were applied to check the validity of the FEM simulation tests. The results show that the FEM simulation tests are good ways for predicting and optimizing the VBHF.

Process window diagram of conical cups in hydrodynamic deep drawing assisted by radial pressure

Major defects in forming of conical cups are wrinkles and rupture.Hydrodynamic deep drawing assisted by radial pressure（HDDRP） is a sheet hydroforming process for production of shell cups in one step.In this work,process window diagrams（PWDs） for Al1050-O,pure copper and DIN 1623 St14 steel are obtained for HDDRP process.The PWD is determined to provide a quick assessment of part producibility for sheet hydroforming process.Finite element method is used for this purpose considering the process parameters including pressure path,and the blank material and its thickness.Numerical results are validated by experiments.It is shown that the sheets with less initial thickness and higher strength show better formability and uniformity of thickness distribution on final product.The results demonstrate that the obtained PWD can predict appropriate forming area and probability of rupture or wrinkling occurrence under different pressure loading paths.

Effect of Friction on the Drawing Process of Hot-Galvanized Sheet Steel

A probe test method was employed to detect the friction condition of the interfaces between tools and blank. At the same time a self-developed measurement apparatus to realize the probe test method was also presented. Based on the analysis of force, a correlative friction model was also given. With the self-developed measurement apparatus,the effects of three kinds of lubricating oils which were in common use during the process of sheet steel drawing were studied. By probing the friction coefficient values of different lubricating oils during the drawing process of the hot-galvanized sheet steel （steel brand： ST07Zn）, we can see that the friction caused by PK oil was the lowest, so the effect of PK oil was the best. Then PK oil was used as the base lubricating oil and some solid additive powers was added into it to make a new type lubrication （named as L oil）.The result of test proved that the new lubricating oil had remarkable effect on the drawing process of hot-galvanized sheet steel.

Influence of process parameters on deep drawing of AA6111 aluminum alloy at elevated temperatures

To gain a deep insight into the hot drawing process of aluminum alloy sheet, simulations of cylindrical cup drawing at elevated temperatures were carried out with experimental validation. The influence of four important process parameters, namely,punch velocity, blank holder force(BHF), friction coefficient and initial forming temperature of blank on drawing characteristics(i.e.minimum thickness and thickness deviation) was investigated with the help of design of experiments(DOE), analysis of variance(ANOVA) and analysis of mean(ANOM). Based on the results of ANOVA, it is shown that the blank holder force has the greatest influence on minimum thickness. The importance of punch velocity for thickness deviation is 44.35% followed by BHF of 24.88%,friction coefficient of 15.77% and initial forming temperature of blank of 14.995%. After determining the significance of each factor on forming characteristics, how the individual parameter affects characteristics was further analyzed by ANOM.

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.

Textures of high-strength and low-expansion Fe-Ni alloy wires during cold-drawing processes

Textures of high-strength and low-expansion Fe-Ni alloy wires during cold-drawing processes were investigated using X-ray diffraction （XRD） and electron back scatter diffraction （EBSD） techniques. The experimental results show that the 〈111〉 and 〈100〉 fibre textures are the main texture components, and crystalline grains in the surface are more fine and uniform than those in the center of Fe-Ni alloy wires during cold-drawing processes. It is found that the volume fraction of the 〈111〉 fibre texture component determined by quantitative regression calculation of the Gaussian distribution function reaches more than 60% and the strong 〈111〉 fibre texture component favors the torsional property of Fe-Ni alloy wires.

Processing limit maps for the stable deformation of dieless drawing

Tin bronze wires were produced by dieless drawing. The effects of heating power, the distance between cooler and heater as well as feeding speed on the diameter, the temperature field, and the deformation region profile of the wires were investigated. The results indi-cated that each processing parameter exhibited both lower and upper limits of stable deformation based on the criterion of stable deformation with the diameter fluctuation of ±0.05 mm. Both the temperature and its gradient of the deformation region increased with increasing heating power under stable deformation, but decreased with an increase in feeding speed. As the distance between cooler and heater increased, the temperature of the deformation region increased and the slope of the deformation region profile decreased. The processing limit map of sta-ble deformation exhibited a closed curve and the unstable deformation consisted of wire breakage and diameter fluctuations.

Modifying the Traditional Analyzing Method of Cylindrical Workpieces’ Deep Drawing Process by Using a Novel Loop Material Theory Method

In this paper, the traditional empirical coefficient method and a novel loop material analytical method presented by the authors have been compared and discussed by analyzing several practical cylindrical workpieces’ deep drawing projects. Also, some conclusions about how to modify the traditional analyzing method of cylindrical workpieces’ deep drawing process could be concluded and the necessity of this modification could be proved.

Effects of processing parameters on figuration during the GMAW rapid prototyping process

As a deposition technology, gas metal arc welding （GMAW） has shown new promise for rapid prototyping of metallic parts. During the process of metal forming using the arc of GMA W, low heat input and stable droplet transition are critical to high quality figuration. The effects of various processing parameters on figuration quality were studied in the experiment of GMA W rapid prototyping using the wire of ERSO-6 , including welding voltage, wire feeding rate, welding speed and so on. The optimal parameters for ERSO-6 are obtained. Simultaneously, it is verified that the rapid prototyping parts with favorable structures and quality can be achieved under the conditions of low heat input and stable droplet transition.

Finite element simulation on the deep drawing of titanium thin-walled surface part

The deep drawing of titanium thin-walled surface part was simulated based on a self-developed three-dimensional finite element model. After an investigation on forming rules, a virtual orthogonal experimental design was adopted to determine the significance of processing parameters, such as die radius, blank holder force, and friction coefficient, on the forming process. The distributions of thickness and equivalent plastic strain of the drawn part were evaluated. The results show that die radius has a relative major influence on the deep drawing process, followed by friction coefficient and blank holder force.

Numerical Analysis of Hydroforming Deep Drawing of Conical Cup

Aided by the FE-code. analysis is carried to find the proper hydroforming deep-drawing condition for the perfect forming of a conical cup that can not be drawn successfully by conventional deep drawing method. Hydraulic counter pressure must be reasonably controlled, otherwise defects such as fracture and wrinkling can not be avoided. Therefore, the forming procedure is divided into three stages, and the counter pressure is adjusted intentionally to make the blank clamped onto the punch at a suitable time, then deformation at dangerous area is resisted by the effect of the counter pressure and the conical cup can be formed without defects.

An Approach to Determine Tool Speed for Cylindrical Part Drawing

In order t o evaluate inertial effect on sheet deformation in the simulation of stamping pr ocesses by dynamic explicit FEM, an analytic model is established for analyzing cylindrical cup drawing process. The main factors governing the extent of inerti al effect on sheet deformation pattern are investigated by energy method, and th e approach to the selection of reasonable tool speed for dynamic analysis of sta mping processes is proposed. The effectiveness of the present approach is furthe r demonstrated and justified by the numerical result herewith provided.

Software Development for the Management of CAD Drawings

A software for the management of computer aided design（CAD） drawings was developed. It can be used to classify and register information including geometric features of the drawings, and to search appropriate reference drawings matching the given conditions of a new design. The thumbnails of the drawings can be displayed in an order of preference and can be used to zoom and access the PDF file or CAD data of a selected drawing. The thumbnails and the data structure are two key elements of the software.

Wear behaviors and lubrication medium of TiC/Al_2O_3 ceramic wire drawing dies

The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawing force was investigated. The wear mechanisms of the ceramic drawing dies were investigated. Worn bore surfaces of the ceramic drawing dies were examined by scanning electron microscopy. The results show that lubricant media have great influence on the drawing force. The drawing force is the smallest when a grease lubricant is used. But alteration of drawing velocity has scarcely any influence on the drawing force. Detailed observations and analyses of the die wear surface reveal that the most common failure of the ceramic drawing die is the wear in the invariable zone and bearing zone owing to the greater press stresses. Abrasive and adhesive wear are found to be the predominant wear mechanisms for ceramic drawing die.

A COMPUTER MULTIMEDIA BOOK OF MECHANICAL DRAWING

This report gives a view of a computer multimedia book of mechanical drawing. This electronic book is developed under Windows and Chinese Star to form an integrated system on a CD-ROM. In the electronic book, graphics, images, 3D animation, audio, video and text techniques of computer multimedia are applied. The techniques, methods, contents and purpose of developing this system are introduced.

深冲钢炼钢区段专线化层流运行模式实践

鉴于某钢厂深冲钢炼钢区段运行效率较低、能量耗散较大、过程稳定性较差等问题,对炼钢区段各工序内时间-事件进行解析,协调优化各工序作业时间;并结合生产线特点,构建“一对一”层流专线化生产路径。生产实践表明:采用专线化层流运行模式生产深冲钢,可避免前、后工序间交叉运行时铁素流在空间、时间、能耗上的不确定性;工序间链接时间缩短,炼钢区段总作业时间从247.9 min缩短至193.5 min;过程能量耗散减少,转炉终点温度从1671.7℃降至1653.9℃。

二轴摩擦型V带传动工作过程分析与带速选择

引入梯形中位线定理,以几何图形和胡克定律对各力之间关系,进行了清晰的阐述。提出了有效拉力释放系数Hα的概念,定义了常规因子K_(1),提供了一种最大有效拉力的计算方法,通过比例系数Xα证明了Hα的适用性和准确性。绘制了综合性能曲线图,探讨了紧边极限拉力F_(1)、松边极限拉力F_(2)、最大有效拉力F_(ec)、最大功率P_(0)等随带速v的变化规律。给出了最大应力与功率曲线图,阐明了最佳带速的选择方法、任意包角α0下最大功率P_(0)的计算方法,定义了安全系数S_(0)。

铝型材冷却初拉伸控制

针对铝型材加工过程中的拉伸夹具及冷却时间度量问题,设计适用于不同型号的拉伸夹具,确定了不同加工参数下的最佳冷却时间。通过优化拉伸夹具的设计和冷却时间的控制,能够提高铝型材的加工质量和生产效率。实验结果表明,该方法能够有效地改善铝型材的性能和形状,具有较高的应用价值。

薄壁水槽拉深变形规律研究及工艺优化

为解决几何形状复杂且不对称及采用3次拉深工艺成形的薄壁水槽模具制造及试模难度大和成本高的问题,研究了该水槽采用多道次拉深工艺时板料的变形规律,同时对其拉深工艺进行了优化。利用Dynaform有限元分析软件对薄壁水槽拉深一序、拉深二序和拉深三序进行数值模拟分析,研究了关键工艺参数对成形结果的影响规律并得出最优的工艺参数,最后通过拉深实验对该工艺方案进行了验证。根据工艺优化方案,得出了最优工艺参数。拉深一序:从0 s至0.01 s,压边力恒定40 kN,从0.01 s至拉深结束,压边力从40 kN线性增长至500 kN;凸模、凹模、压边圈与板料之间的摩擦因数分别为0.2、0.05、0.05;模具间隙为0.66 mm。拉深二序:凸模、凹模、压边圈与板料之间的摩擦因数分别为0.15、0.1、0.1;压边力为500 kN。拉深三序:采用合适的拉深筋布置方式及阻力值。实验结果表明,在不同拉深工序中分别侧重调控不同拉深工艺参数可以有效控制薄壁水槽的减薄量。

3维激光扫描技术在历史建筑保护中的应用

为了更好地将即时定位与地图构建(SLAM)3维激光扫描技术应用在历史建筑保护中,实现利用3维点云模型对历史建筑进行数字化保护,以云南白族历史建筑为研究对象,采用了SLAM 3维激光扫描技术获取历史建筑高精度点云模型,该技术不仅能快速地完成数据采集工作、提高历史建筑数字化保护工作的效率,还可以形成历史建筑丰富的数字化成果;通过对实验区数据的理论分析和实验验证,证明了SLAM 3维激光扫描技术在历史建筑数字化保护中的可行性。结果表明,距离中误差为0.004 m,点位中误差为0.037 m和0.021 m;SLAM 3维激光扫描技术能够快速、准确地完成历史建筑数据采集过程并形成高精度点云模型,基于该模型提取的平立剖面图能够达到相关规范精度要求。该研究为历史建筑数字化保护提供了一种新的思路和方法,有望在未来的应用中发挥更为积极的作用。