共查询到20条相似文献,搜索用时 31 毫秒
1.
Hak-Gon Noh Woo-Jin Song Beom-Soo Kang Jeong Kim 《Journal of Mechanical Science and Technology》2014,28(8):3263-3271
Electromagnetic forming (EMF) is a high strain rate forming process that uses Lorentz force. In this study, electromagnetic forming with a rectangular block shape in the center of the forming die was examined to determine the possibility and applicability of EMF. However, the high speed of the process in the absence of a medium between the coil and the workpiece results in bouncing of the workpiece, which may result in poor forming. So, in this study, the use of a cushion plate is proposed as a means of reducing the degree of bounce in an EMF process. A 3D electromagnetic numerical model using a spiral forming coil was considered. An RLC circuit, coupled with the spiral coil, was numerically simulated to determine the deformation behavior and design parameters, such as the input current and the magnetic forces. A cushion plate was used between the forming coil and the sheet to be deformed to reduce the extent of bounce. In the numerical simulation, the sheet was found to be well fitted to the objective die with the cushion plate. The simulation results showed that the extent of bounce was drastically reduced because of the velocity direction of the workpiece and the cushion plate. The experiment was performed using 24 kJ to deform Al 1100 with a thickness of 1.27 mm, based on the simulation results. The deformed sheet was well formed, and closely fitted the objective die with a minimum of wrinkling, relative to the results obtained without a cushion plate. As a result, an EMF process with a middle-block die was successfully established both numerically and experimentally to reduce the bouncing. 相似文献
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Xiaohui Cui Jianhua Mo Fei Han 《The International Journal of Advanced Manufacturing Technology》2012,59(5-8):521-529
Numerical simulations of electromagnetic forming process offer the opportunity to overcome the multi-physics filed coupling problems. The purpose of this work is to establish a three-dimensional (3D) finite element model which can be used for non-axisymmetrical 3D models. And the simulation method will serve as a guide to analyze arbitrary complex 3D models in the future. In each time step, the transient magnetic forces and the joule heat generated by electromagnetic code are used as the loading condition to predict the deformation of the tube by mechanical code and the temperature variation of the tube by thermal code, respectively. Whereafter, the tube geometry is updated according to the deformation result. The simulation result of displacement at the center of the tube with time and the final tube profile are in better agreement with the experimental ones. The lows of the strain, stress, strain rate, and the temperature variation are analyzed. The changes of the magnetic force on the tube are also analyzed. 相似文献
4.
3D Numerical simulation method of electromagnetic forming for low conductive metals with a driver 总被引:1,自引:1,他引:0
Fenqiang Li Jianhua Mo Haiyang Zhou Yang Fang 《The International Journal of Advanced Manufacturing Technology》2013,64(9-12):1575-1585
Electromagnetic forming (EMF) process is a high-speed forming process which can inhibit warping, reduce springback, and improve the formability of material at room temperature. In general, the electromagnetic forming process is applied to high-conductive metals such as copper, aluminum, and their alloys. In order to solve the problem of the low formability of titanium alloy, the electromagnetic forming process can be applied to form titanium alloy. The effects on the forming properties of titanium and other low-conductive metals must be studied before the EMF process is used. To that end, this paper presents a tool: a 3D numerical simulation method of electromagnetic forming with a driver. First, the electromagnetic field distribution and electromagnetic forces are calculated using the ANSYS/EMAG software. The resulting data are then imported to ABAQUS/Explicit software to carry out mechanical analysis. Although the electromagnetic field calculation does not take the deformation of the blank into account, the results accurately reflect the law of the deformation. This method is especially suitable for cases involving small deformations, such as tube compression and embossing. The calculation can also be used to simulate the impact forming process between the driver and the blank. 相似文献
5.
Lifeng Wang Z. Y. Chen C. X. Li S. Y. Huang 《The International Journal of Advanced Manufacturing Technology》2006,30(5-6):395-400
Electromagnetic forming (EMF) is an uncommon metal working process that relies on the use of electromagnetic forces to deform metallic workpieces at high speeds. It is expected to overcome some formability barriers of materials. EMF process analysis is the foundation of theoretical analysis. However, the electromagnetic sheet metal process is very difficult to describe, because of the complexity of magnetic pressure distribution. In this paper, a numerical modeling of the electromagnetic sheet metal process is performed using a finite element method, and a series of simulations on free bulging are carried out using the FEA program ADINA. The dynamic deformation process of sheet metal is investigated. At last, some experiments are made and those simulations agree well with the experimental results. 相似文献
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Electromagnetic blank restrainer (EMBR) is a new technology that was recently developed to control material movement in sheet metal forming processes. Magnetic attraction on the ferrous sheet metal is the intrinsic property of EMBR. Such magnetic force is quantified using Maxwell's stress tensor to assess the feasibility of EMBR in the sheet metal forming process. The 3D finite element analysis (FEA) of an electromagnetic system is conducted to determine the distribution of magnetic flux density on contacting surfaces of the sheet metal. The distribution is then used to estimate the magnetic force. Experiments have been conducted to measure the magnetic force and compare with results from the FEA. Biaxial-loading apparatus has been built to measure restraining forces on the sheet metal with blankholder, drawbead, and EMBR. All the restraining forces are put together in a chart to see where each method stands with respect to one another. In order to evaluate the quality of forming with each method, an experimental die has been built. The die forms a channel in a single stroke and provides a direct indication of how each restraining method controls blank movement in the die. The real advantage of EMBR lies in the effectiveness of force control and its flexible location in a sheet metal forming die. To prove this, a prototype has been built in a tryout die where house appliance panel is formed with blankholder and EMBR. EMBRs are locally installed in the die and actively controlled during the forming process. The part formed with EMBR shows a significant improvement in the forming quality. At the end of this paper, two immediate impacts that EMBR can bring to the sheet metal forming industry are also discussed. 相似文献
8.
J.P.M. Correia M.A. Siddiqui S. Ahzi S. Belouettar R. Davies 《International Journal of Mechanical Sciences》2008,50(10-11):1466-1475
Electromagnetic sheet forming is a high-velocity forming process driven by the coupled electromagnetic and mechanical phenomena. The deformation of the workpiece is governed by the body forces (Lorentz forces) that results from a pulsed magnetic field produced by a flat spiral coil. Formability can be increased using this high-velocity forming technique due to the inertial forces and high strain rates. In this study, we consider the electromagnetic and the mechanical aspect of the process as two independent problems. The finite difference method has been employed to solve the electromagnetic equations. The pressure acting on the sheet and due to the Lorentz forces is estimated neglecting the influence of the sheet velocity on the magnetic field. Then it has been treated as a load in the mechanical problem. Numerical simulations of the mechanical problem have been performed with the commercial finite element code ABAQUS/Explicit. The magnetic pressure has been introduced in ABAQUS/Explicit as an analytical pressure distribution. The general objective of this study is to better understand the complex phenomenon of deformation and the influence of viscoplastic material behaviour during the simulation of a free bulging electromagnetic sheet forming process. 相似文献
9.
A theoretical model is presented to calculate the lubricant film thickness in an unsteady hydrodynamic lubrication of cup-shaped products to be formed by the ironing process. The model covers the development of hydrodynamic lubrication in various phases of the ironing process. The model provides equations for estimating the lubricant film thickness for each phase. Experiments were conducted to study the effect of lubricant viscosity on die expansion and punch force in making cup-shaped products by the ironing process. It was found that the die expansion varied between unlubricated and lubricated cups and depended on the lubricant viscosity. The film thickness was estimated from the difference between the increased die/punch clearance, which was calculated from the expansion, and the lubricated cup wall thickness. The theoretical film thickness was compared with the estimated film thickness based on the die expansion measurement. 相似文献
10.
M. Goodarzi T. Kuboki M. Murata 《The International Journal of Advanced Manufacturing Technology》2007,35(1-2):66-74
Tube shear bending is a beneficial technique to realize considerable small bending radii. The authors have investigated the
tube shear bending process of circular tubes experimentally. Moreover, an elastoplastic 3D finite element simulation has been
conducted, aimed at clarifying the forming mechanism. Both the experiment and simulation results indicate that, in order to
perform successful forming, the value of the applied pushing force on the tube must be appropriate. In this paper, the mechanism
of defect generation was clarified. Two failure criteria were introduced and employed to recognize the occurrence of defects
in the simulation. The effects of the die corner radius, as the main parameter, on the defect generation of circular A1050
aluminum tubes were investigated both by experiments and numerical simulation. From the results, the formability of tube on
dies with different corner radii applying various pushing pressures was clarified. Moreover, the influence of the die radius
on the dimensional accuracy of the deformed tube regarding cross-section ovality and thickness changes of the deformed tube
was evaluated. The results of this study indicate that, whilst a small bending radius results in high cross-section ovality,
increasing the die corner radius raises the wrinkling tendency of the tube. However, the die radius has a small effect on
the suitable values of pushing pressure required for a successful shear bending deformation. Moreover, the effect of the die
corner radius on the thickness strain of the deformed tube is insignificant. 相似文献
11.
针对弹体温成形实际生产过程中模具寿命低及壁厚差大的问题,通过对温成形工艺参数的分析,提出弹体温成形过程的改进方案,即在温挤压工步之前增加预成形工步,在温挤压工步之后增加变薄拉深工步.经对改进工艺的计算机模拟及实验验证表明,此改进的工艺能够减小壁厚差,降低凸模温升,延长凸模寿命. 相似文献
12.
M. H. Sadeghi H. Haghighat M. A. Elbestawi 《The International Journal of Advanced Manufacturing Technology》2003,22(11-12):775-785
A system for geometric and physical simulation of the ball-end milling process using solid modeling is presented in this paper. A commercially available geometric engine is used to represent the cutting edge, cutter and updated part. The ball-end mill cutter modeled in this study is an insert type ball-end mill and the cutting edge is generated by intersecting an inclined plane with the cutter ball nose. The contact face between cutter and updated part is determined from the solid model of the updated part and cutter solid model. To determine cutting edge engagement for each tool rotational step, the intersections between the cutting edge with boundary of the contact face are determined. The engaged portion of the cutting edge for each tool rotational step is divided into small differential oblique cutting edge segments. Friction, shear angles and shear stresses are identified from orthogonal cutting data base available in the open literature. For each tool rotational position, the cutting force components are calculated by summing up the differential cutting forces. The instantaneous dynamic chip thickness is computed by summing up the rigid chip thickness, the tool deflection and the undulations left from the previous tooth, and then the dynamic cutting forces are obtained. For calculating the ploughing forces, Wu's model is extended to the ball-end milling process [21]. The total forces, including the cutting and ploughing forces, are applied to the structural vibratory model of the system and the dynamic deflections at the tool tip are predicted. The developed system is verified experimentally for various up-hill and down-hill angles. 相似文献
13.
B. Yang W. G. Zhang S. H. Li 《The International Journal of Advanced Manufacturing Technology》2006,29(5-6):453-458
To investigate the effect of the loading path on the forming result and get the reasonable range of the loading path in tube
bulge hydroforming process, a mathematical model considering the forming tube as an ellipsoidal surface is proposed to examine
the plastic deformation behavior of a thin-walled tube during the tube bulge hydroforming process in an open die, and thus
different loading paths are gained based on this model. The finite element code Ls-Dyna is also used for simulating the tube
bulge hydroforming process. The effect of the loading paths on the bulged shape and the wall thickness distribution of the
tube are discussed, and then the reasonable range of the loading path for the tube bulge hydroforming process is determined. 相似文献
14.
B. Yang W.G. Zhang S.H. Li 《The International Journal of Advanced Manufacturing Technology》2006,29(5):453-458
To investigate the effect of the loading path on the forming result and get the reasonable range of the loading path in tube
bulge hydroforming process, a mathematical model considering the forming tube as an ellipsoidal surface is proposed to examine
the plastic deformation behavior of a thin-walled tube during the tube bulge hydroforming process in an open die, and thus
different loading paths are gained based on this model. The finite element code Ls-Dyna is also used for simulating the tube
bulge hydroforming process. The effect of the loading paths on the bulged shape and the wall thickness distribution of the
tube are discussed, and then the reasonable range of the loading path for the tube bulge hydroforming process is determined. 相似文献
15.
Chi-Chen Huang Jung-Chung Hung Chinghua Hung Chia-Rung Lin 《The International Journal of Advanced Manufacturing Technology》2011,56(9-12):1039-1048
Tube spinning process is a metal forming process used in the manufacture of axisymmetric products and has been widely used in various applications. Finite element analysis has been successfully applied to the tube spinning processes, but no temperature effects have been considered on neck-spinning. For this reason, the aim of this research is to investigate numerically the neck-spinning process of a tube at elevated temperature. The commercial software Abaqus/Explicit was adopted in the simulation. For the construction of the material model, special uniaxial tensile tests were conducted at elevated temperature and various strain rates, since the material is sensitive to strain rates at high temperature. Comparisons between experimental and simulation results on thickness distribution and the outer contour of the spun tube are discussed. During the final stage, the average deviations between the simulation and experiment were 10.65% in thickness and 3.03% in outer contour. Good agreement was found between experimental and simulation results. The influence of the coefficient of friction, roller translation speeds, and the tip radius of the rollers were also investigated through numerical simulation. 相似文献
16.
Quanliang Cao Liang Li Zhipeng Lai Zhongyu Zhou Qi Xiong Xiao Zhang Xiaotao Han 《The International Journal of Advanced Manufacturing Technology》2014,74(1-4):361-368
This paper presents a simple and efficient method for the analysis of dynamic behavior of the workpiece in the electromagnetic forming process. A two-dimensional (2D) axisymmetric finite element model with the equations of electrical equivalent circuit, electromagnetic field, and mechanical field has been developed for calculating the discharge currents through the forming coil, the magnetic forces acting on the workpiece, and the plastic deformation of the workpiece. By considering the effects of the sheet geometry and velocity on the above parameters, the method realizes the full coupling between the electromagnetic fields and the workpiece deformation, which should be more accurate than the existing loose coupling and sequential coupling simulation methods. 相似文献
17.
Seong-Chan Heo Young-Ho Seo Tae-Wan Ku Beom-Soo Kang 《Journal of Mechanical Science and Technology》2011,25(2):429-439
Exhaust gas recirculation (EGR) cooler consists of a number of heat transfer tubes that have relatively larger net area than
that of flat type tubes. The surface of the tubes is made up with lots of grooves and protrusions for enlarging the net heat
transfer area. Most tubes are manufactured through forming processes, such as bending, spinning, roll forming, stamping and
so on. Therefore, a series of fracture or defect can occur during the various forming processes. In this study, the manufacturing
process of a dimple-type rectangular heat transfer tube used for an EGR cooler system is investigated based on the numerical
simulation and the experimental approach. A prototype of the tube is designed and modified to a newly designed tube considering
the conservation of the net heat transfer area based on the numerical and analytical approach. Formability evaluation of the
tube sheet is carried out by using forming limit curves based on the plastic instability conditions. Strain- and stress-based
forming limit curves are utilized to ensure the strain path independence. The newly designed tube having a number of dimples
on the both sides are manufactured by the press forming process. Thickness distributions for the principal cross-sections
are observed from both the simulation and the experiment and compared each other. From the results, it is confirmed that the
forming process is robust to manufacture the dimple type rectangular tubes with the comparison of thickness, and application
of the forming limit curves. 相似文献
18.
大型复杂型面铝合金翻边件电磁成形是一个电磁场和结构场耦合作用下的复杂塑性成形过程。由于大型复杂型面的影响,使得铝合金翻边件在电磁成形过程中的塑性流动行为与传统带凸模翻边成形不同。基于松散耦合法建立耦合电磁场和结构场的大型复杂型面铝合金翻边件电磁成形有限元模型,研究采用1层、2层和3层平板线圈电磁翻边下的板料塑性流动行为,并采用试验研究揭示了不同压边力控制下板料法兰部分塑性流动规律。结果表明,当采用3层平板线圈时,翻边件的复杂型面部分完全贴膜,法兰部分材料进入凹模腔的部分更多,促使板料发生更多的塑性流动;不同压边力控制下,法兰部分由塑性流动产生不同的工件形式,在压边力不足时,法兰部分产生明显的起皱现象;通过合理的压边力控制,可得到贴膜性良好的大型复杂型面铝合金翻边件。 相似文献
19.
This paper describes a three-dimensional numerical model based on finite volume method to simulate heat transfer and fluid flow in laser–tungsten inert gas (TIG) hybrid welding process. To simplify the model and reduce the calculation time, keyhole dynamics are not considered; instead, a new modified volumetric heat source model is presented for the laser source to take into account the effect of the keyhole on the heat transfer into the workpiece. Due to the presence of arc current, an appropriate electromagnetic model based on the Maxwell equations are also solved to calculate electromagnetic forces in the weld pool. The results of computer simulation, including temperature, current density, electromagnetic, and melted material velocity field, are presented here. Furthermore, several dimensionless numbers are employed to recognize the importance of fluid flow driving forces in the weld pool. It is deduced that the fluid flow has an important effect on the weld pool shape. It is also founded that among the driving forces, Marangoni force is dominant fluid force in the weld pool. Besides, calculated results of hybrid welding process are compared with those of TIG and laser welding processes. The weld pool depth is relatively the same, but the width of the weld pool is highly larger in hybrid welding than lone laser welding. Eventually, the presented model is validated by comparison between calculated and experimental weld pool shape. It is founded that there is a good agreement as the capability of this model can be proved. 相似文献
20.
针对轮边驱动电动汽车设计了一种直驱式的电磁悬架作动器。针对作动器存在的电磁力波动大的问题,提出了从空载定位力及负载波纹力两方面进行抑制的方法。建立作动器的磁场理论计算模型,通过对绕组磁链及感应电动势进行解析,验证了有限元模型的正确性。空载情况下基于有限元模型参数化分析了端部齿长度对定位力的影响,改进了定子长度。以感应电动势总谐波畸变率THD值作为评价指标,考虑了负载情况下的波纹力,通过改进槽口的宽度,以减小THD值及电磁力的波动。结果表明:当定子长度为182 mm时,定位力最小为24.0N,减小了75.6N;当槽口宽度为4.5 mm时,感应电动势THD值最小为4.5%,波纹力减小了3.2N。改进后作动器电磁力波动值仅为20.8N,降幅为80.1%,有效解决了波动力大的问题。 相似文献