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1.
This paper investigates the conventional and hydromechanical deep drawing of circular tailor welded blanks (TWBs) with a linear weld line. TWBs offer the possibility to combine different materials, different thicknesses and different coatings within one part, as to optimally fit the applied loads with the lowest possible weight. By combining the hydromechanical deep drawing process with TWBs, a new range of applications can be offered. For the investigations experimental trials are carried out, as well as finite‐element simulations. The material parameters of the parent materials and of the weld line are determined and included in the modelling of the TWB. A tool die is designed allowing the hydromechanical deep drawing of TWBs while taking into account the sealing of the TWB and the gap in thickness created by blanks of different thickness. In this way a different blank holder pressure can be applied on each side of the TWB, using a segmented blank holder and a multi‐point cushion system. The goal of this study is to investigate the influence of the counter pressure on the deep drawing process of TWBs with particular interest given to the weld line movement during the forming process. It is found that the deep drawing process can be simulated accurately by the finite‐element analysis and that the weld line movement plays a crucial role in the deep drawing of a sound part.  相似文献   

2.
This paper covers the study of hydromechanical deep drawing of cylindrical steel cups using a controllable sealing mechanism between the blank and the draw ring. Precise control of the counter pressure curve over the punch stroke in hydromechanical deep drawing is difficult to accomplish due to fluid leakage. A controllable sealing mechanism has been developed and tested; this resulted in a die set designed to withstand fluid pressures up to 200 MPa with draw ratios up to 3.0. A micro‐metering pressure control valve is used to limit the developed counter pressure to avoid die breakage. Furthermore, the ability of transferring complex microstructures from the punch onto the blank surface is investigated.  相似文献   

3.
Aluminum 7075 is a functional aerospace alloy that has high strength and low formability during room temperature deep drawing. Therefore, to avoid warm forming process and relative difficulties, careful control in the process design is needed to enhance quality of drawn part and improve die life. In the present work, an attempt was made to experimentally and numerically study the effect of hydrodynamic deep drawing process such as die geometry and fluid pressure on thinning ratio and punch force. Statistical analysis based on response surface methodology was carried out to correlate empirical relationship between die corner radius, punch corner radius and die fluid pressure as process factors and maximum thinning ratio and punch force as responses. Sensitivity analysis was also performed to find out the factor having greatest impact on aforementioned responses. Further, optimization was carried out by using desirability approach to find out optimal parameter setting to attain minimum thinning and forming force simultaneously. Results indicated that punch and die corner radius followed by fluid had significant effect on the process quality characteristics. Moreover, setting of 9.3 mm punch corner radius, 2 mm die corner radius and 26 MPa fluid pressure resulted in 71% desirability incorporating 31% thinning and 175 MPa punch force. The obtained optimal results were then verified through both FE simulation and confirmatory experiment.  相似文献   

4.
Sheet hydroforming, which is based on an active working medium, results in advantages over conventional forming techniques that make this technology interesting for the production of components with a large surface area. In order to expand the range of applications for this method, the current limits must be extended and the obstacles eliminated. One important aspect here is finding a solution to the conflict between a reliable tool sealing and a controlled material flow, particularly in the filling and preforming phases of the hydroforming process. One way of achieving progress in this area is to employ multipoint technology. In order to exploit multipoint cushion technology ‐ the potential of which has been proved in conventional deep‐drawing operations ‐ to extend the limits of sheet hydroforming, this technology has to be developed further, similarly to the multipoint cushion systems used in deep‐drawing, and adapted to the process‐specific conditions of sheet hydroforming.  相似文献   

5.
The continuing trend of miniaturization has entailed the need for new cost efficient and fast methods for processing small parts. In this paper a new non‐mechanical process for the forming process of micro deep drawing is presented. This new deep drawing process utilizes a laser initiated plasma shock wave at the target, which forms the sheet. Several pulses can be applied at one point and therefore high forming degrees can be reached without increasing the energy density. In this paper the pressure of the shock wave is measured in order to enable optimizations of the process in future. Furthermore, an analysis of the thickness distribution over the deep drawn cups will be introduced. Laser deep drawing of samples made of Al99.5, Cu and stainless steel sheet metal with thicknesses of 20 μm and 50 μm are shown. Finally the efficiency of the laser shock forming process in calculated.  相似文献   

6.
The work detailed in this paper focuses on a new forming strategy for the CNC incremental sheet forming (ISF) process that is appropriate to form steep flanges, e.g. for parts designed for deep‐drawing. When parts are designed for deep‐drawing, they usually contain steep or rectangular side walls that cannot be manufactured using the standard ISF strategies. Unlike prior approaches to obtain steep flanges through ISF, the present method achieves a rough approximation to the final part already in the preforming stage. This can be accomplished without excessive sheet thinning due to sheet bending and stretching at this stage. As a consequence, additional material can be used for the finishing stages, thus yielding a final part with largely reduced thinning. After basic studies on a simple benchmark problem, the new bending/stretching strategy is tested with an industrially applied part that is usually produced by deep‐drawing. Finally, the ISF workpiece is evaluated against the deep‐drawn component with respect to sheet thickness and geometric accuracy.  相似文献   

7.
The motivation of the presented research work was to provide an approach to reduce the high fluid pressures and clamping forces needed in hydroforming presses to cup small form elements. Using local heating, small form elements like domes and creases can be formed at very low pressures of 2‐3 MPa, whereas cold forming requires pressures which are 20‐50 times higher. Apart from the proportion of forming temperature and work pressure, temperature distribution is very important, and can be adjusted by a special laser beam shaping optic or scanning processing head. The second method is more flexible in regard to element sizes and outlines, but has a lower thermal efficiency. Line network analyses were carried out showing great improvements in the resulting strain distribution. In order to characterise the general improvement of the material's formability, forming limit curves (FLC) were generated, using the bulge‐test. The results prove the extended forming limit of the laser‐assisted warm cupping process. For the investigations different materials were used: the deep drawing steel DC05, the aluminium alloy 5182 and the magnesium alloy AZ31.  相似文献   

8.
9.
Dieless drawing is an example of flexible metal forming processes. The investigation of the main process parameters and their interdependence is the prerequisite for the deliberate choice of input parameters to get the desired quality of the workpiece. Drawing force, drawing velocity, and temperature are the main control parameters. But only the temperature can be influenced locally whereas the force and the velocity can be adjusted only globally. Because of this special importance of the temperature analytical and numerical models for the temperature distribution along the deformation zone have been developed.  相似文献   

10.
王伟  黄宇星  余鸿敏 《工程科学学报》2018,40(11):1373-1379
油箱壳外形复杂,拉深成形过程中容易出现侧壁起皱和圆角处破裂的缺陷,成形工艺参数的确定非常重要.结合分类与回归决策树(classification and regression tree,CART)的人工智能技术和模型交叉验证方法,通过调用Python平台开源库Scikit-Learn对油箱壳拉深成形数值模拟结果进行知识挖掘,筛选出对油箱壳拉深成形影响大的工艺参数;以基尼指数(Gini index)最小化作为最优特征值及最优切分点选择的依据,构建了工艺参数与性能指标关系的CART决策树,提取出了可靠的工艺设计规则.油箱壳拉深实例表明,CART决策树理论的知识发现技术是实现板料成形过程数值模拟结果潜在知识挖掘的可行途径.  相似文献   

11.
High‐pressure forming of metal sheets is an innovative forming technology for the production of complex components and offers high potentials to improve the properties and qualities of sheet metal parts. This report describes investigations of a newly developed active‐elastic tool system referred to as ACTEC system. Unlike the use of a comparable semi‐rigid tool system, the ACTEC system shows improvements with respect to the material flow in the flange area and reduced sheet thinning in critical corner regions of the workpiece. In addition, the clamping forces respectively sealing forces necessary to avoid leakage in the tool system during the forming process can be reduced. Moreover, the specific design of the ACTEC‐system as well as current experimental examinations are presented and discussed.  相似文献   

12.
Forming of automotive leightweight parts using aluminium offers numerous advantages. Compared to other wrought aluminium alloys, in particular AlMg‐alloys generally show a good formability which is favourable for the production of complex parts. However, forming of Mg‐containing alloys at room temperature leads to yielding patterns preventing their implementation for class‐A‐surface applications. Furthermore, the formability of steel still exceeds that of AlMg‐alloys at room temperature. Thus, in the present study, sheet metal forming is applied at a temperature range that is typical for warm forming. It is supposed to profit from the advantages of warm forming like high achievable strains and improved surface quality of the formed part, while not having the disadvantages of long production times and high energy consumption, which is correlated with superplastic forming. Applying fluid‐based sheet metal forming in this paper, nitrogen is used as fluid working medium to satisfy the demand on high temperature resistance. Concerning the blank material used, formability of Mg‐containing aluminium alloys shows strong strain rate sensitivity at elevated temperatures. To figure out the optimal strain rates for this particular process, a control system for forming processes is developed within the scope of this paper. Additionally, FE‐simulations are carried out and adapted to the experiment, based on the generated process data. FE‐investigations include forming of domes (bulging) as well as shape‐defined forming, having the objective to increase formability in critical form elements by applying optimal strain rates. Here, a closed‐loop process control for gas‐pressure forming at elevated temperatures is to be developed in the next stages of the project.  相似文献   

13.
针对薄壁板材零件小圆角特征成形制造难的问题,提出了一种新型胀压复合成形工艺.其关键工艺参数为:预成形高度、预成形凹圆角大小和终成形胀形压力与背压凸模运行速度匹配关系.预成形高度决定了终成形小圆角的材料储备,预成形凹圆角的最佳值为充液拉深时凸模圆角可取的最小值,通过理论分析给出了预成形高度和预成形凹圆角的计算方法.建立了胀压复合成形过程力学模型,通过应力状态分析给出了不同胀形压力与背压凸模运行速度匹配关系下坯料圆角区变形状况.同时基于有限元模拟和工艺试验,研究了预成形高度和终成形胀形压力与背压匹配路径对试验件成形质量的影响,验证了理论分析的准确性,并证明了该新工艺的适用性.  相似文献   

14.
Working media based forming processes show advantages compared to the conventional deep drawing in the range of sheet metal parts with complex geometry details. By High Pressure Sheet Metal Forming (HBU), complex parts can be formed with reduced tool costs, fewer process steps, and improved part properties, particularly by the use of high strength steels. In order to use these advantages to full capacity, the material flow into the area of the geometry details needs to be optimised. The key element for the material flow control is a multi‐point blank holder. In combination with flange draw‐in sensors, a closed loop flange draw‐in control can be built up which guarantees a reproducible material flow and, consequently, defined part properties. Furthermore, a favourable pre‐distribution of sheet metal material can be reached which leads to a widening of the process limits. Considering a large area sheet metal part with a complex door handle element as example, strategies for the material flow control will be discussed in this paper. The conclusions are based on FE‐simulations as well as experimental findings.  相似文献   

15.
The ultimate aim of this work is the development of methods for the simulation of manufacturing process chains such as forming→cutting→heat treatment→joining, providving maximal efficiency without significant loss of accuracy. In the current work, we make the first step in this direction by considering the case of forming of the new high strength steel LH®800. The work begins with a characterization and metallographic investigation of this new steel. Following this, a combined hardening model appropriate for this steel is formulated and identified. The identified model is then validated with the help of the finite‐element simulation of draw‐bending. On this basis, the model was then used to simulate cup deep‐drawing. This process was also simulated with a so‐called one‐step solver which is much faster than the finite element simulation. The results of these two simulations are compared with the results of the deep‐drawing experiment.  相似文献   

16.
The paper presents the results of extensive experimental research focused on the analysis of deformation conditions in multi‐pass drawing process. The wire rod of medium and high‐carbon steel manufactured with application of controlled cooling rate after hot rolling was chosen as the material to be drawn. Suitability of the wire rod for the multi‐pass drawing process was assessed by means of detailed analysis of mechanical properties of a material before drawing, after each pass as well as of the final product. The drawing process was realised without intermediate heat treatment, assuming maximum possible reduction to be attained. The effect of history of deformation (distribution and number of unit reductions, die geometry) on the mechanical properties of drawn wires was analysed. The force parameters of the drawing process were also evaluated in detail, which allowed for an attempt to determine the optimum drawing conditions. The separate part of work was the upper‐bound process modelling which included calculations of the components of power of deformation as well as the analysis of state of strain by means of strain redundancy factor evaluation. Finally, conclusions were formulated concerning suitability of the investigated wire rod for deep cold working as well as the influence of history of deformation on the product quality.  相似文献   

17.
张宝生 《冶金设备》2013,(4):69-70,15
炉顶煤气放散阀作为炼铁高炉系统控制炉内压力的安全类阀门,在高炉生产中起着至关重要的作用,但由于内部碟簧的失效,时常导致炉顶放散阀因密封力不够而泄露,造成高炉内压力不稳定,主要介绍了一种新的技术,能够在阀门在线使用的情况下测量阀门的实时密封力,以做到及时调整密封力的目的。此在线监测的技术已经获得了国家专利(专利号:ZL 2010 2 0694335.5)。  相似文献   

18.
在D400-13煤气加压机应用轴端氮气密封替代原迷宫式密封,以充分利用叶轮前后压差,消除轴向推力,减少机械磨擦,从而保证密封效果,改善风机性能,提高密封寿命。使用表明,改造后消除了煤气外泄现象,提高了设备开机率,年直接经济效益15.22万元。  相似文献   

19.
This work presents the outcomes of investigations on dynamic effects and parameters of Hydro‐Impulse Forming (HIF) and their influence on the shaping process. Parameters for the blanks exposed to hydro‐impulse forming are defined by FE‐simulations, which use AUTODYN 2D‐3D software. These simulations enable a clear visualization of the processes that occur in the material and the working media. Results are presented for the simulated deep drawing of a semi‐sphere for the aluminium alloy A2024 and the steel QStE340. A larger influence of dynamic forces on the forming process was detected by numerical simulations on the “transmission medium ‐ die ‐ blank” scheme. These outcomes were confirmed by experimental investigations and a classification of the typical malformations during HIF (unusual in conventional forming processes). As shown by the performed experiments and numerical simulations, HIF offers great advantages in comparison with common forming processes, e.g. with regard to the creation of deeper reliefs and low residual springing.  相似文献   

20.
Based on the deformation characteristic of regular polygonal box stamped parts and the superfluous triangle material wrinkle model, the criterion of regular polygonal box stamped parts without wrinkle was deduced and used to predict and control the wrinkle limit. According to the fracture model, the criterion of regular polygonal box stamped parts without fracture was deduced and used to predict and control the fracture limit. Combining the criterion for stamping without wrinkle with that without fracture, the stamping criterion of regular polygonal box stamped parts was obtained to predict and control the stamping limit. Taken the stainless steel 0Cr18Ni9 (SUS304) sheet and the square box stamped part as examples, the limit diagram was given to predict and control the wrinkle, fracture and stamping limits. It is suitable for the deep drawing without flange, the deep drawing and stretching combined forming with flange and the rigid punch stretching of plane blank. The limit deep-drawing coefficient and the minimum deep-drawing coefficient can be determined, and the appropriate BHF (blank holder force) and the deep-drawing force can be chosen. These provide a reference for the technology planning, the die and mold design and the equipment determination, and a new criterion evaluating sheet stamping formability, which predicts and controls the stamping process, can be applied to the deep drawing under constant or variable BHF conditions.  相似文献   

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