共查询到20条相似文献,搜索用时 15 毫秒
1.
The polymer injection forming process is a recent invention for producing plastic?Cmetal hybrids. It is a combination of injection molding and sheet metal hydroforming process in which polymer melt serves as a pressure medium. This paper presents the experimental investigations on the non-Newtonian nature of thermoplastic melt as pressure medium. The objective of this work is to identify the presence of non-hydrostatic pressure distribution within the cavity and its influence on the final shape of the formed sheet metal component. Experiments are conducted with center-gated injection mold under varying processing conditions. The development of localized cavity pressure during the process is recorded and evaluated against the final shape of formed sheet metal. It has been observed that higher injection rate, higher injection temperature, and higher melt flow index of the processed polymer is necessary for the uniform pressure distribution and subsequently uniform forming of the sheet metal. 相似文献
2.
采用弹塑性大变形更新的Lagrange有限元方法研究了铝板 /塑料混合成型过程中铝板的成形过程和变形特点。结果表明 ,当塑料熔体压力从 30MPa增大到 5 0MPa时 ,铝板凸缘区已基本不再参与变形 ,铝板上两个板厚减薄较严重的大塑性变形区在此阶段形成。模底接触区与自由变形区交界处的大塑性变形区依次处于板料曲面内双向伸长变形和平面应变状态 ;模腔入口圆角区与自由变形区交界处的大塑性变形区由两部分构成 ,其中与模壁接触部分依次处于板料曲面内双向伸长变形、拉伸变形和平面应变状态 ,另一部分依次处于板料曲面内双向伸长变形和平面应变状态。 相似文献
3.
1 INTRODUCTIONHybridformingisanewmethodformanufactur ingofmetalsheetandplasticcombinedmacro com positecomponents[1] .Twometalsheetswith pre treatedsurfacesareheldtogetheralongtheiredgesbyclampingoperationofthemoldforhybridformingthroughtheinjectionmachine … 相似文献
4.
5.
6.
For sheet metals, the endurance to fracture under different strain paths may be different. Based on plastic deformation energy, the sheet metal forming limit is calculated, and the relationship model between maximum allowable integral value of the general plastic work criterion and the strain path is built. In addition, the strain-hardening exponent, anisotropy coefficient and the initial thickness of the material are also taken into account to consider their effects on forming limit. In order to simplify the process of parameter determination, only uniaxial tension test is used to calculate the material property parameters and necessary limit strain, and the expression of the criterion is determined finally. Then the limit strains under other strain paths between uniaxial tension to equi-biaxial tension are predicted by the criterion combined with numerical simulation of the forming process. The criterion is also applied to limit strain prediction under bilinear strain path. 相似文献
7.
8.
PHYSICAL MODELLING OF ISOTHERMAL DIE FORGING PROCESS OF Ti-ALLOY STRUCTURAL AIR-FRAME PART WITH E TYPE CROSS-SECTION AND VARYING THICKNESS RIB 总被引:5,自引:0,他引:5
1.IntroductionItisadifficulttasktoforgethestmcturalair--framepartswithvaryingthicknessrib,becauseshapeoftheforgingsiscomplicated.Heightandthicknessofrib,distancebetweenhoribsandthicknessofweballhaveinfluenceonmetalflow.Thedefectssuchaslaps,eddyflow,flowashandextrussiondefectoftenresultsfromPOordiedesignandimproperchoiceofthestartingshapeofthebellet.TherejectrateOfconventionaldieforgingOfstructuralair--framepartishigh,becausethetemperatUreofworkpiecedecreasesfasteranddistributingoftemperature… 相似文献
9.
Polymer Injection Forming (PIF) and Polymer Injection-Compression Forming (PICF) are new manufacturing technologies for sheet metal-polymer macro-composites, which result from the combination of injection moulding and sheet metal forming. In these processes, a metal blank is formed inside an injection mould by using the pressure of the molten polymer that, after cooling, permanently bonds to the metal sheet creating a fully finished product in only one production step. This paper presents a calibrated multi-physics numerical model of the processes that proves to be suitable to investigate the mutual metal-polymer interactions and to provide a reliable tool in designing the process as well as its control. 相似文献
10.
The gas atomization is the process that a liquid mass is disintegrated into a collection of liquid melt droplets by the impact of high velocity gas stream and solidified into metal particles. However, the liquid melt sheet breaking mechanism has not been fully understood. So the experimental research was carried out under the condition of lower melt superheat. The results reveal that there are three approaches about melt metal sheet's breakage: from the edges of sheets, from inner surface of sheets, and disrupted by other droplets and sheets. The approach of melt sheet breakage is dependent on its thickness. The thicker sheets (above 25μm) are disintegrated mainly by the way of droplet's departing from edges, and the thinner sheets (below 10 μm) are chiefly breaking from the inner surface. 相似文献
11.
In the course of this work, an extended material model for a carbon steel sheet metal has been developed based on Hill’48 yield criterion, considering temperature-dependent plastic anisotropy coefficients. This material model is applied on a polymer injection forming process in which the sheet metal heats up to a critical forming temperature through the contact with the plastic melt. At this temperature range blue brittleness occurs. The elastic properties, the yield stress as well as the plastic anisotropy coefficients of the sheet material become significantly different compared to those at room temperature. It should be emphasized that especially temperature-dependent anisotropy coefficients are not yet considered in most common material models. With the help of the presented modelling approach a more precise modelling of the temperature-dependent carbon steel material behavior can be realised. 相似文献
12.
An Arbitrary Lagrangian-Eulerian(ALE) method was employed to simulate the sheet metal extrusion process, aiming at avoiding mesh distortion and improving the computational accuracy. The method was implemented based on MSC/MARC by using a fractional step method, i.e. a Lagrangian step followed by an Euler step. The Lagrangian step was a pure updated Lagrangian calculation and the Euler step was performed using mesh smoothing and remapping scheme. Due to the extreme distortion of deformation domain, it was almost impossible to complete the whole simulation with only one mesh topology. Therefore, global remeshing combilaed with the ALE method was used in the simulation work. Based on the numerical model of the process, some deformation features of the sheet metal extrusion process, such as distribution of localized equivalent plastic strain, and shrinkage cavity, were revealed. Furthermore, the differences between conventional extrusion and sheet metal extrusion process were also analyzed. 相似文献
13.
板料成形过程模具圆角摩擦测试实验装置的研究 总被引:2,自引:0,他引:2
板料成形研究中的一个难点是如何采用实验方法定量测定板料成形过程中板料与模具之间的摩擦系数.通过对板料成形时的变形特点进行分析,提出一种新的板料成形过程模具圆角摩擦测试实验方法,并研制出相应的摩擦测试实验装置.该实验装置考虑了板料成形时周向收缩、厚向增厚的变形特点,能够在线测试出室温和加热状态下板料成形过程模具圆角处的摩擦系数.摩擦测试结果表明,所研制的摩擦测试装置具有灵敏度高、可重复性好、使用方便的特点,为深入研究板料成形过程中摩擦系数随工艺参数的变化规律提供了实验手段. 相似文献
14.
H.-L. Chan A.D. Spence M.P. Sklad 《International Journal of Machine Tools and Manufacture》2007,47(1):191-203
This paper presents a new approach to sheet metal strain and surface analysis using data collected with a high-accuracy coordinate measuring machine mounted laser digitizer. First, the flat sheet metal blank is electrochemically etched with a hollow centre circular grid pattern. As the blank is pressed into the desired shape, the resulting strain deforms the circles into approximately elliptical shapes. The sheet metal is then laser digitized every 0.1 mm and the (X,Y,Z) surface coordinates plus reflected light intensity (grey level) are simultaneously recorded. Parallel computer-based image processing separates the darker ellipse grid points from the lighter background, and orthogonal least-squares data fitting estimates the major and minor surfaces strains. Results can be presented as a forming limit diagram, or as a derived thickness strain plot. Surface analysis is achieved by computing and plotting a maximum curvature map and then quantifying feature depth as the normal direction amplitude between the locally highest and lowest points. Implementation of the research for a representative industrial part is included. 相似文献
15.
16.
浅拉伸小曲率汽车覆盖件成形特点及质量控制 总被引:2,自引:0,他引:2
浅拉伸小曲率汽车覆盖件的冲压成形与深拉伸覆盖件相比 ,具有不同的变形特点 ,它的主要问题是塑性变形小 ,导致冲压成形后稳定性差 ,刚性不足 ,曲面形状不良等 ,对此 ,进行了变形特点分析 ,采取多方面的措施 ,增加其塑性变形量 ,得到了高质量的冲压件。 相似文献
17.
介绍了用注塑机改装的注吹一次成型全自动吹瓶机回转模部件结构设计。在通用注塑机动、定板之间加装一个回转模部件 ,定板做成注射凹模部件 ,动板上安装开边模部件 ,合模时 ,熔融塑料注射到凹模与回转模芯棒之间的空腔形成吹瓶用的管坯 ,而在动板侧(开边模部件)将回转模芯棒上的管坯吹制成开边模合模型腔形成的瓶形。整个工作过程用微电脑或可编程序控制器(PC)控制。 相似文献
18.
Fundamental investigations on the material flow at combined sheet and bulk metal forming processes 总被引:1,自引:0,他引:1
The class of combined sheet and bulk metal forming (SBMF) processes denotes the forming of sheet metals with typical bulk forming operations. As a consequence, simultaneous 2D and 3D stress and strain states are present. Furthermore the local shape elements formed out of the sheet plane are in the magnitude of the sheet thickness. This paper deals with process combinations upsetting/lateral extrusion and deep drawing/upsetting. It has been shown that an insufficient mould filling is nearly inevitable using conventional tooling systems. Hence, the prospect of newly developed forming approaches will be discussed. 相似文献
19.
《Journal of Materials Processing Technology》2014,214(9):1820-1827
Continuous roll forming (CRF) is an effective process to manufacture swept surface parts of sheet metal. The forming tool in CRF is a pair of small-diameter bendable forming rolls, a swept surface is formed continuously after the rotating rolls sweep out the whole sheet metal blank. The two bent rolls and the non-uniformly distributed roll gap along the rolls’ length make the sheet metal bent in longitudinal and transverse directions simultaneously, the cross-section curve of the formed swept surface is controlled by the curved profile of the forming rolls and the spine curve is controlled by the differential elongations of sheet metal generated by roll gap. In this paper, a necessary condition for the formation of a swept surface is proposed and analyzed, the parametric equations of the formed surface in CRF are derived and the method to determine the roll gap for forming a given swept surface is presented. The numerical simulations and analyses on the CRF processes demonstrate the validity of the presented theoretical models. The experimental and measured results show that the formed surfaces are in good agreement with the desired surfaces, and swept surface parts with good forming precision can be obtained by CRF process. 相似文献