RESEARCH ON THE EVALUATION METHOD OF FRICTION AND LUBRICATION IN DEEP DRAWING

The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other plastic process. The common test methods in laboratories are analyzed. It shows that though all those test methods can test the friction coefficient, the probe test method is most suitable for the research of friction and lubrication and the process in deep drawing, for this method is identical with the actual work condition either from the test principle or deformation status of the blank. Last the successful application in the deep drawing simulator newly developed the the probe method are intro- duced in detail.

OPTIMIZATION AND METHOD OF DRAWING CONTROL IN BLOCK CAVING AT TONGKUANGYU MINE

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Research on the Reform of the Course“Reading of Concrete Structure Plan and Construction Drawings”Under the Background of“Promoting Teaching and Learning Through Competitions”

The inherent teaching approach can no longer meet the demands of society.In this paper,current issues within the teaching landscape of architectural engineering technology in higher vocational colleges as well as the policies and teaching demands that formed the basis of this model were analyzed.The study shows the importance of the implementation of the teaching model“promoting teaching and learning through competitions.”This model puts emphasis on the curriculum and teaching resources,while also integrating the teaching process and evaluation with competition.These efforts aim to drive education reform in order to better align with the objectives of vocational education personnel training,while also acting as a reference for similar courses.

Effect of Friction Coefficient on Deep Drawing of 6A16 Aluminum Alloy for Automobile Body

Based on the ABAQUS/Explicit finite element method,the forming force changing trend of deep drawing test for 6A16 aluminum alloy plate after pre-aging and storage at room temperature for one month was simulated under friction coefficient ranging from 0 to 0.22.The lubricants selected for the tests were mechanical oil,butter and dry film lubricant,and the friction coefficient of these lubricants were 0.05,0.10 and 0.15,respectively.Microstructural evolution of 6 A16 aluminum alloy plate during drawing forming was investigated by OM,SEM and EBSD.The results showed that,with the increase of friction coefficient,the stress,strain and deformation degree in deformation zone increased,while the grain size in deformation zone decreased.Thus,the hardness of the cup-typed component increased with the increase of friction coefficient.Butter-lubricated cups had the highest tensile strength and yield strength after paint-bake cycle.The combination of simulation results and microstructure analysis of 6A16 aluminum alloy plate after drawing forming indicates that the appropriate lubricant is butter.

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.

Formability improvement and blank shape definition for deep drawing of cylindrical cup with complex curve profile from SPCC sheets using FEM

In the current work,to predict and improve the formability of deep drawing process for steel plate cold rolled commercial grade(SPCC) sheets,three parameters including the blanking force,the die and punch corner radius were considered.The experimental plan according to Taguchi's orthogonal array was coupled with the finite element method(FEM) simulations.Firstly,the data from the test of stress-strain and forming limit curves were used as input into ABAQUS/Explicit finite element code to predict the failure occurrence of deep drawing process.The three parameters were then validated to establish their effects on the press formability.The optimum case found via simulation was finally confirmed through an experiment.In order to obtain the complex curve profile of cup shape after deep drawing,the anisotropic behavior of earring phenomenon was modeled and implemented into FEM.After such phenomenon was correctly predicted,an error metric compared with design curve was then measured.

FINITE ELEMENT ANALYSES OF THE EXTRUSION FLOWS OF BOGER FLUIDS WITH END-DRAWING AND GRAVITY-DRAWING

The spinning flow of Boger fluids and the gravity-drawing extrusion flow of a Newtonianas well as a Boger fluid have been simulated by using the stream-line finite element method and thetechnique of matching the finite element solutions with those of one-dimensional spinning equations.The recoverable shear strain is proved not to be a basic parameter in characterising thespinning flow of Boger fluids.For Newtonian fluids this technique predicts the experimental jetshape accurately.For Boger fluids,the numerical simulation agrees with the experimental data of spin-ning flow reported by Sridhar et al.,but seems to give an insufficient swelling and over contractionof the jets when drawn by its own weight,compared with the experimental results of Trang andYeow.It implies that the Oldroyd-B model fitting the viscometric-flow data fails to describeaccurately the elasticity and extensional viscosity in the extrusion flow of Boger fluids with gravi-ty-drawing.

ANALYSIS OF DRAWING UNDER LUBRICATION OF NON-NEWTONIAN LUBRICATING MATERIALS

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Discrimination of Junctions in Line Drawing by Computer

For discrimination of the common W-junction and Y-junction in the labels of line drawing for a three-dimensional manifold plane surface with trihedral vertices, the existing algorithms are almost using angles between two adjacent lines and W-junction and Y- junction＇s definitions, and other complex methods. This passage gives four methods with their detailed mathematical inference processes in order to use these algorithms implemented by computer. The algorithms listed are Angle Summation method and Points to the Line method, Triangle methods which are the Triangle Area method and the Cross method. When the computer programs discriminate junctions, by comparison, the Angle Summation method and Points to the Line method are less efficacious than the Triangle method, and Cross method is more efficacious than the Triangle Area method in the Triangle method.

PREDICTION AND CONTROL OF BOTH WRINKLE AND FRACTURE LIMITS ON CYLINDRICAL CUP MULTI DEEP DRAWING

Based on the superfluous triangle material wrinkle model,the no wrinkle limit criterion of cylindrical cup multi deep drawing is calculated as the prediction and control of the wrinkle limit.According to fracture model,the no fracture limit criterion of cylindrical cup multi deep drawing is calculated as the prediction and control of the fracture limit.Combining the no wrinkle limit criterion with the no fracture limit criterion,the no wrinkle and no fracture limit criterion and diagram on cylindrecal cup multi deep drawing are given as the prediction and control of both wrinkle and fracture limits.In accordance with this can determine the limit deep drawing coefficient and minimum deep drawing coefficient,and can choose the deep drawing coefficient of multi deep drawing,blank holder force and deformation force by optimization choice method.Theory calculation and test data are highly consistent,and suitable for no flange multi deep drawing,flange multi deep drawing and rigid punch expanding

考虑硬化历史的圆筒形件二次拉深极限拉深比的解析模型

以圆筒形件二次拉深成形为例,基于主应力法和板料弯曲理论,考虑材料硬化历史、壁厚比t_(min)/t_(max)、凹模圆角半径和摩擦因数的影响,建立了一种预测圆筒形件二次拉深极限拉深比的解析模型,并对SUS304不锈钢板料进行了拉深试验验证。结果表明:解析模型的预测值与试验结果吻合较好;考虑硬化历史的解析模型与未考虑硬化历史的模型相比二次拉深极限拉深比相差约10%;摩擦因数、凹模圆角半径对二次拉深极限拉深比有显著影响,摩擦因数越大,二次拉深极限拉深比越小;凹模圆角半径越大,二次拉深极限拉深比越大。

有限回采空间内贫矿资源无底柱分段崩落法低贫损开采方案研究

做好无底柱分段崩落法的贫损控制对于矿山经济效益及环境保护具有重要意义,但当矿床开采条件复杂、矿石品位较低时,矿石贫损控制难度将会大幅增加,在此条件下如何做好矿石贫损控制一直是崩落法开采方向的重要关注点。金川龙首矿西二采区无底柱分段崩落法采场仅可布置4个分段,回采空间十分有限,不利于矿石的贫损控制,加之西二采区矿石品位较低但经济价值较高,因此在开采过程中需要严格控制矿石贫损。针对西二采区的复杂开采条件及贫损控制需求,提出了一种“首采分段总量控制出矿、中间分段低贫化出矿、最末分段低贫化出矿+辅助进路回收残留矿石”的组合式低贫损回采方案。以西二采区为工程背景,设计并制作了一种高仿真度的物理放矿模型并对该方案展开了试验研究。结果表明:即便是在暂时不考虑回收最末分段残留矿石的情况下,该方案可使西二采区崩落法采场的矿石回收率达到75.6%,而废石混入率仅为6.0%,在确保矿石回收率的基础上显著降低了矿石贫化。该方案在现场应用后,实际的矿石回收指标与试验结果基本接近,表明该方案在西二采区有限回采空间内实现了贫矿资源低成本、高质量回收的总体目标。

光子晶体结构生色真丝织物的制备及应用研究

为实现真丝织物的结构生色,文章分别利用真空辅助过滤法和手绘法在白色真丝织物上构筑光子晶体结构。进一步探究真空辅助过滤法中微球组装液体积浓度对结构色的影响规律,分析微球在真丝织物上形成光子晶体运动机制,讨论真丝织物上光子晶体结构色的虹彩效应,并探究手绘法在真丝织物光子晶体结构生色中的应用效果。结果表明:真空辅助过滤法中聚(苯乙烯-甲基丙烯酸),即P(St-MAA)微球组装液的体积浓度为2.4 L/m^(2)时,真丝织物的两面能同时获得光子晶体结构色,此时正反面结构色的反射率峰值在18%左右;在真空辅助过滤法中,P(St-MAA)微球在真丝织物上形成光子晶体结构的过程遵循“先反后正”堆积原则,即织物反面先形成光子晶体,随后微球进一步透过织物堆积在正面。此外,该光子晶体结构生色真丝织物的虹彩效应不明显,与常规染料或颜料着色效果接近;手绘法可以获得图案化的光子晶体生色结构,较适合于个性化加工。该研究为光子晶体结构生色在真丝织物着色中的应用提供参考。

甘孜藏族自治州寺庙壁画绘制方法及风格分析

甘孜州寺庙壁画从属于卫藏地区壁画风格体系,16世纪形成于康巴地区的“噶玛嘎孜画派”唐卡绘画对本地区寺庙壁画产生影响。本文在分析传统寺庙墙面制作、壁画绘制的基本方法前提下探究卫藏地区传统寺庙壁画风格,以及在秉承传统绘画技法中形成的“噶玛嘎孜画派”唐卡画与壁画平行发展相辅相成的纽带关系;梳理甘孜州寺庙壁画现状以及发展趋势,有助于形成壁画技法传承、风格演变脉络的理性认知,建立壁画图像价值判断的客观依据,并在此基础上进行科学保护。

基于BIM技术的施工图智能审查实施策略

建筑信息模型(BIM)技术在我国建筑行业中的应用日益广泛,尤其是在房建施工图审查环节。该文从传统施工图审查存在的问题出发,分析BIM施工图审查与传统审查方式之间的联系,并调研目前国内开展BIM施工图审查的城市,通过对比分析关键技术的优异,分析BIM技术在施工图审查中的优势,阐述BIM智能审查技术的实施策略,为业内开展施工图智能审查提供思路和方向。

多策略检视问题设计 确保试题命制质量——由一道错题引发的思考

在命题实践中,一味求新求异,致使试题所考查的知识点超出中学物理范畴,难以达到检测学生核心素养的发展过程与现有水平的目的.以一个考查连接体的经典错题为例,尝试采用微元法、求导法、极坐标法及Origin绘图4种策略厘清连接体中加速度关联情景,剖析该题错误成因,分析相同知识点在高考题中应如何设问,以规避错误的发生.希望引起一线命题者的共鸣,以此促进命题质量的提升.

民办本科院校教考分离模式下课程试题库建设研究——以“工程制图与CAD”课程为例

传统的教学方式已不能满足人们对更高教育质量的追求,为了实现培养新型人才的目标,教考分离成为传统教学模式改革的重要方向。此模式不仅有助于保证教学和考试的公正性,对提高教师的教学质量和学生的综合素质也具有重要作用。“工程制图与CAD”是工科专业的核心课程,以“工程制图与CAD”课程为例,构建了规范化、标准化的试题库,并在浙江树人学院进行了教考分离下的试题库改革。结果表明,民办本科院校教考分离模式下课程试题库建设及应用,可有效提升教师的教学质量和学生的学习能力。