FEM SIMULATION AND EXPERIMENTAL RESEARCH ON THE SHEET BLANKING

Both experiment and simulation are made on the AlMg4 . 5Mn0 .4 sheet blanking with 1 % , 10% and 20% relative clearance respectively. The cutting force curves and the cutting surface parameters which can be used to describe the quality of the blankings are measured. Simulation is accomplished by MARC Autoforge software package. Calculated cutting forces are always bigger than measured ones. All difference between experiment and simulation is not greater than 20% . It is feasible making virtual experiment on workstation to estimate the cutting force and to predict the quality of the workpiece for new material using certain blanking technical parameters.

Ductile damage and simulation of fine-blanking process by FEM

Based on the Curson Tvergaard void damage plastic potential equation and by using orthogonal rules of plastic material, the influence of void volume fraction on stress and strain fields was introduced into Levy Mises flow rules. The variation principle of rigid plastic material with void degradation was demonstrated. Furthermore, FEM equations coupled with damage factor were presented to study the void growth and the criterion to judge the damage was also given. Using the developed system, the fine blanking process was simulated and the sheared surface of the part edge was predicted. Meanwhile, the influence of process parameters, such as punch die clearance, V ring force, counter force, radius of punch and die edges, on the height and quality of the sheared surface was analyzed. The calculation results were compared with the experiments, which can be used to guide the design of fine blanking process.

Effects of parameters on rotational fine blanking of helical gears

The application of fine blanking to the manufacturing of helical gears directly from a strip has been restricted due to the traditional linear cutting stroke of the punch and die.In this work,rotational fine blanking which combined the linear and rotational motion of punch and counterpunch was applied for the forming of helical gears.A three-dimensional(3D) rigid-plastic finite element model was developed on the DEFORM-3D platform.By finite element simulation and analysis,the influences of key parameters on the punch load and cut surface were investigated.It is shown that: 1) with increasing the counterforce or helical angle,the punch load and the depth of die roll increase; 2) with increasing blank holder force,the punch load increases while the depth of die roll decreases; 3) V-ring indenter facilitates an improvement in the quality.The results of this research reveal the deformation mechanism of rotational fine blanking of helical gears,and provide valuable guidelines for further experimental studies.

COUPLED ELECTRICAL-THERMAL-MECHANICAL ANALYSIS FOR ELECTRICAL/LASER HEATING ASSISTED BLANKING

A coupled electrical-thermal-mechanical analysis is conducted for electrical/laser heating assisted blanking. Two novel localized-heating methods, electrical heating and laser-heating, recently proposed for small-part blanking, are investigated with FE simulations. Results show that electrical heating would result in an advantageous distribution of temperature in a 316 stainless steel work-material. A desired temperature distribution may also be achievable for a copper work-material, if laser beam is used. Both electrical heating and laser-heating enable to reduce the blanking force and increase the aspect ratio achievable by blanking. The simulation also demonstrates that both electrical heating and laser-heating can result in desired temperature-distributions at sufficiently high heating-rates, ease of implementation and application. Comparatively, electrical heating could generate more favorable temperature distribution for small-part blanking.

Effects of Break-through State and System Rigidity on Vibration and Noise in Blanking

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Finite Element Optimization of Vee-ring Factor in Fine-blanking Process

The vee-ring is one of the most characteristic features of the fine-blanking process which is derived from the conventional blanking. With the vee-ring, a counter plate and some other working parameters, a component with a precise geometry and smoothly blanked surface can be produced without any major secondary operations. However, these working parameters are always empirically determined or determined by trial-and-error method, which is time-consuming and expensive. In this study, a numerical simulation method was used to analyze the effect of vee-ring factors on product quality, such as distance between vee-ring and punch, vee-ring height and blank holder force, so as to obtain as high clean cut ratio as possible. During the simulation, the model was assumed as axisymmetric one and the workpiece was considered as rigid plastic material, meanwhile the tools were defined as rigid bodies so as to shorten the computational time. A damage model taking into account the influence of hydrostatic stress was used to simulate material fracture in fine-blanking. The result obtained from the simulation indicated that with the help of vee-ring, the metal material near the shear band does not flow with the punch penetration and high compressive stress in the shear band is generated. Consequently, higher clean cut ratio can be obtained with a vee-ring model than the one obtained with a plane blank holder model. Furthermore, the longer the distance between vee-ring and punch is, the higher the height of roll-over becomes.

Dynamic Constitutive Model of Physical Simulation in High-Speed Blanking for C5191 Phosphor Bronze

Strain hardening,strain rate strengthening and thermal softening data of C5191 phosphor bronze at highspeed blanking are not easy to be obtained with a general measure method,therefore,it is quite difficult to establish the dynamic constitutive model.To solve this problem,the tensile properties at a strain rate of 1 s^(-1) by GLEEBLE-3500,and dynamic tensile conditions at strain rates of 500,1 000 and 1 500 s^(-1) by split Hopkinson tensile bar (SHTB) apparatus are studied.According to these test data,the classic Johnson-Cook equation is modified.Furthermore,the modified Johnson-Cook equation is validated in the physical simulation model of high-speed blanking.The results show that the strength of C5191 phosphor bronze maintains a certain degree of increase as the strain rate increasing and presents a clear sensitivity to strain rate.The modified Johnson-Cook equation,which has better description accuracy than the classical Johnson-Cook equation,can provide important material parameters for physical simulation models of its high-speed blanking process.

Comparative Study on Shearing Edge Quality Influence of the Change of Tool Geometry in Fine-Blanking for Non-homogeneous Materials

Excellent quality of shearing edge implies that a s mo oth cutting edge without tearing will be observed on the whole edge surface. Thi s is one of the most significant features of the Fine-blanking process. To achi eve such a superb blanking edge quality in fine-blanking, there actually involv es quite a large number of factors, such as blanking speed, processing material, product shape, lubrication and tool geometry, to be considered simultaneously d uring the operation. Nevertheless, the thorough investigations on different effe cts of those critical factors for different kinds of popular and applicable mate rial are rare and limited. Thus, the objective of this paper is mainly focused o n the study of the quality influence of tool geometry change in fine-blanking f or non-homogeneous materials. However, the most obvious change of the tool geo metry during the operation will be the essential variation of the nose radius of the punch. This is because the nose radius usually seriously deteriorates with the increasing service period in mass production which eventually causes the ent irely lose of the specific features of the fine-blanking process. Therefore, a tailor-made experimental study was carried out to investigate the relationship between the punch nose radius and the shearing edge quality, such as blanked edg e finish, burr height and die-roll height, during fine-blanking for different types of material. Five punches with each specified nose radius (Rp), 0.00 mm, 0.25 mm, 0.50 mm, 0.75 mm and 1.00 mm, and four kinds of blanking material ( Mil d steel SS400, Stainless steel AISI316L, Copper alloy UNSC16200 and Aluminium al loy AA6063 ) were employed throughout the study. Subsequently, features of the s heared edge surfaces and data of each experiment were observed and captured for further analysis in this research. Consequently, findings show that an increase of punch nose radius would produce a higher percentage of fracture of blanked ed ge and increase the amount of burr height. In overall comparison, it is found th at mild steel and copper alloy do provide better surface edge finish with higher percentage of sheared area and less burr height than that of stainless steel an d aluminium alloy.

Mechanism of localized severe plastic deformation and damage fracture in fine-blanking using mixed displacement and pressure FEM

A mixed displacement-pressure updated Lagrange FEM was used to simulate the severe plastic deformation, which can overcome shear locking and volume locking. Together with adaptive remeshing technique based on strain gradient and surface curvature, the strain localization in severe plastic deformation can be captured. Schiffmann damage density was used to predict the developments of damage and fracture in sheet metal. The intensive dislocation and slip appear under the action of severe shear deformation, and metallic grains are flattened and elongated in shear band. Because of the existence of large radius of die edge, the flow direction of grains changes, and the grains are elongated and simultaneous. As a result, it is not easy to cut the grains off, and outer surfaces with clean cut are formed.

Application of CAD redevelopment in process design of stepping-mode laser blanking

To design a stepping-mode laser blanking process,in this study,CAD software was redeveloped based on VBA and a computer interface was established in the process design system. The program employs the modularization method to perform functions including one-key initialization of the process planning environment,creation and deletion of blanking steps,automatic identification of belt coordinates,recognition of the number of blanking steps in each domain,and the output and import of process data. The difficult problem of recognizing CAD block references with the same name in the automatic acquisition of belt coordinates is solved using the selection sets method,which greatly improves the efficiency of the process design,while also guaranteeing rapid development of the flexible data mold in stepping-mode laser blanking.

The Applied Research of Fracture in Three-point Bending to Blanking of Bearing Steel

The application of fracture in three-point bending to blanking of bearing steel is studied in this paper. Several mechanical models of stress blanking are discussed at first. And then the experiments have been made in special equipment of three-point bending designed by us. Several problems, such as the suitable span, the relations between bending and tension bending complex, the ratio of blanking length to the diameter, the relations of blank length to force, the feature of fracture, are studied through the experiments. The suitable parameters of three-point bending to blanking, depth and tip radius of notch and the ratio between blanking length and stick diameter have been proposed.

Investigation on ductile fracture in fine-blanking process by finite element method

In order to continuously analyze the whole fine-blanking process, from the beginning of the operation up to the total rupture of the sheet-metal, without computational divergence, a 3-D rigid visco-plastic finite-element method based on Gurson void model was developed. The void volume fraction was introduced into the finite element method to document the ductile fracture of the sheet-metal. A formulation of variation of the rigid visco-plastic material was presented according to the virtual work theory in which both the effects of equivalent stress and hydrostatic pressure in the deformation process were considered. The crack initiation of the sheet was predicted and the crack propagation was geometrically fulfilled in the simulation by separating the nodes according to the stress state. Furthermore, the influences of different state-variables on the deformation process were also studied.

Effect of Ultrasonic Vibration on Deformation in Micro-blanking Process with Copper Foil

Effect of ultrasonic vibration on deformation in micro-blanking was investigated with copper foils of different grain sizes using a developed device. It is found that maximum shearing strength is decreased by ultrasonic vibration, and this effect becomes bigger for coarse grain than that for fine grain, which can be attributed to acoustic softening effect considering the absorbed acoustic energy. Surface roughness R_a of smooth zone decreases for the polishing effect of vibration at the lateral contact surface. When ultrasonic vibration is applied, the sheared deformation area becomes relatively narrow, and it leads to the reduction of radius of rollover. The analysis of cross section in sheared deformation area shows that the crack initiation is inhabited for the existence of acoustic softening, and the proportion of smooth zone is increased. Also, angle of crack propagation becomes smaller because of periodic strain, and the angle of facture surface is decreased. As a result, the quality of micro-sheet parts is improved by applying ultrasonic vibration.

wbForming mechanism of collapse angle of fine blanking parts with sharp corners and influence of position of V-ring indenter of die on it

Fine blanking parts with sharp corners produce collapse angles in the fine blanking process,and larger collapse angles can affect the parts’ performance and lifetime. In this paper,a fine blanking part with sharp corners was taken as an example to analyze the forming mechanism of the collapse angles by DEFORM 3 D,then studying the influence of the position of the V-ring indenter of die on the collapse angle. It was concluded that the material’s metal flow line was intensive near the blanking clearance;The equivalent stress area of the material was mainly concentrated around the blanking clearance,and then gradually shrinked to joint of part and scrap;the closer the distance L was,and the smaller equivalent stress area was mainly concentrated around the blanking clearance was,and the smaller collapse angle was.

OPTIMIZING THE CUTTER FOR SLANTING KNIFE CUTTING OPERATION AND ITS BLANKING FORCE

The cutting force under a slanting cutter is discussed.It is not only related to the sheet to be cut and the slanting cutter height,but also to the shape of the cutter.It is from this point of view that the question of optimizing the cutter for slanting knife cutting operation is addressed.Then the general differential equations for the optimum cutter are obtained,and analytic solutions for the workpiece,the contour of which consists of straight lines and arcs,are obtained.A method for solving the general equations is also presented.The cutting force and breaking noise will be minimized for a given slanting cutter height and workpiece if the optimum cutter is employed.

Application of Blank Symbols in Japanese Architecture and Indoor Designs

A symbol is an expression of meaning,while blank symbols express special meanings.By focusing on the application of blank symbols in Japanese architecture and indoor designs,we analyzed the aesthetic principles in Japanese architecture and indoor designs from the perspective of semiotics,such as“Kongji,”“Emptiness,”and“Dying out,”and their minimalist and pure design concepts.Traditional Chinese culture was also further explored,especially the profound influence of the“Chan sect”and the philosophy of“unity of heaven and mankind”on Japanese architecture and designs.This study aims to facilitate the coexistence and mutual appreciation of Chinese and Japanese architectural designs.

留白在极简主义摄影中的应用与审美研究

留白是中国画独特的创作哲学。通过对中国画中留白的作用和留白在极简主义摄影中的应用研究,探讨留白在极简主义摄影中的审美价值。留白的巧妙运用不仅让极简主义摄影的美学价值最大化发挥,而且是中国审美文化的传承。从中国传统美学中汲取创作灵感,有助于推动极简主义摄影的创新与发展,为现代摄影多元化发展提供新思路。

前箱熔体温度对8011铝合金铸轧板坯组织性能的影响

为了稳定提高双零铝箔用铸轧坯料质量,使用电解铝液配料生产规格为7.0 mm×1300 mm的8011铝合金铸轧铝板卷,并利用光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)及电子万能拉伸试验机等手段,研究了不同前箱铝熔体温度(680,690,700,710℃)对8011铝合铸轧板坯微观组织和力学性能的影响.结果表明:随着前箱熔体温度的升高,铸轧板坯晶粒的尺寸呈略微增大再急剧变大的趋势,其抗拉强度和断后伸长率均呈先缓慢降低后急剧下降的趋势;当前箱熔体温度控制在680~700℃时,可获得综合力学性能较佳的铸轧板坯,其平均纵向抗拉强度和横向抗拉强度分别不低于141.87 MPa和138.84 MPa,平均纵向断后伸长率和横向断后伸长率分别不低于29.8%和26.4%.

融合裂缝形态信息的电阻率测井成像图空白条带填充方法

电阻率测井成像图中存在宽度和位置不定的空白条带,而目前常用的空白条带反距离加权插值填充法仅依靠像素点距离参数计算插值,往往导致填充后区域与实测区域纹理不连贯,纹理易呈现直线状,与实际状况不符。为此,将裂缝区域形态与分布信息作为参量,构建插值计算模型,形成融合裂缝形态分布信息的空白条带填充法。该填充算法能根据插值点与裂缝形态拟合线的相对位置关系,动态调整参考点对插值点插值的权重系数,填充后的裂缝区域纹理连贯平滑,更符合裂缝实际形态和分布的规律。实际测井数据应用表明,相较于传统填充方法,采用该方法填充后的裂缝分布拟合线与霍夫变换后曲线相似度提升25%以上,不连贯填充点数量下降88%以上,性能提升明显。该方法的应用成果可为后续测井图像中各种裂缝的智能识别和精确分割提供更好的数据支撑。