单点增量成形过程中成形性的研究现状【中文2787字】【PDF+中文WORD】

单点增量成形过程中成形性的研究现状【中文2787字】【PDF+中文WORD】,中文2787字,PDF+中文WORD,单点,增量,成形,过程,研究,现状,中文,2787,PDF,WORD 附录Ⅰ外文文献及翻译 外文文献 Formability in single point incremental forming: A comparative analysis of the state of the art Single point incremental forming (SPIF) is a method of manufacturing components from sheets of material, with the advantage of little to no customised tooling and otherwise generic setup [1]. This makes it ideal for producing sheet metal prototype components before investing in a stamping mould, or for one-off customised components. SPIF is a type of incremental sheet forming (ISF), a class of processes which includes spinning and shear forming [2]. SPIF has the advantage over a method such as spinning of being able to form asymmetric shapes. In the 2005 paper, Jeswiet et al. [3] succeeded in bringing all the current knowledge at that time and synthesising it into a comprehensive review of the progress and state of the art of asymmetric ISF processes. The decade of research since then calls for an updated review of the progress and understanding of SPIF, including incremental forming of polymer sheets first explored in 2008 [4]. This paper comprises a review of literature on single point incremental forming, specifically to present the process param- eters that influence the formability of the material during forming. Organising the results of this investigation will assist in creating straightforward parameter guidelines and instructions useful for future research and manufacturing real components with SPIF. While commercial and industrial SPIF components have been made in the past, they can be so complex that ‘trial and error’ becomes the most feasible development technique, as using FEA (finite element analysis) would be too computationally expensive. Therefore, a significant challenge is how to develop it into an industrial process using methods more sophisticated than trial and error. The aim of this literature review is to collect relevant data from experimental 3 papers and draw conclusions on maximising the formability of the material used in SPIF. The other aspects of SPIF that are not systematically covered in this review are forming forces, surface quality, geometric accuracy, and resultant material properties. Formability is most commonly quantified by finding the maximum wall angle (Fmax) to which the material can be formed before failure occurs [5], with respect to the horizontal plane. Typically a simple shape, such as a cone or pyramid, is used to determine this maximum wall angle. Multiple parts can be formed, each one with a steeper wall angle than the previous, until a part breaks [6]. Another option is a shape where the wall angle changes from shallow to steep, for example the variable wall angle conical frustum (VWACF) reported in 2007 by Hussain et al. [7]. If this part is used, only one test is needed to determine the wall angle where failure occurs. In the same paper, Hussain et al. [7] compared the VWACF results and results from straight-wall tests and found the latter overestimated Fmax by less than 4% due to its higherstiffness. Therefore, if the exact wall angle at fracture is required for straight wall parts, the VWACF results should be further tested with conical or pyramidal frustums. Any formability test, however, if it is repeated accurately, should give consistent results such that the general effect of a process parameter can be determined. The general effect, further explained in ‘‘Results and discussion’’ section, provides the data that is analysed in this literature review. Many different materials have been used in SPIF, including a variety of metals [3], polymer sheets [4], and other sheet materials such as sandwich panels [8], with a wide range of formability among them. This review will not examine formability limits of specific materials but will instead list them in the parameter analyses to allow comparison between experiments with the same material, for example PVC or AA3003-O. Material type can be seen as the base upon which all other parameters are selected. The thickness of the undeformed material blank is an important parameter and has significant effects on the SPIF process and final part, especially the force needed to deform the sheet which increases with increasing thickness [9]. Sheet thickness is also a factor in the sine law equation for shear forming, where the final thickness (tf) of a part can be calculated from the initial thickness (ti) and the wall angle from horizontal (F). The equation is tf = ti * sin(90 — F) and has been shown to be accurate for SPIF parts formed in a single pass [10]. The absolute values of thickness are not important in this review, as unique material properties mean a 2 mm sheet of one material performs differently to a 2 mm sheet of a different material [3]. Only the general effect of increasing or decreasing the thickness of the undeformed blank has been studied. Tool parameters The tool or punch used in SPIF to deform the sheet has traditionally been one of two types. Firstly, a solid hemispherical tool [2], and secondly, a tool with a ball bearing in a socket, allowing it to roll freely over the sheet [6]. As progress in SPIF and incremental forming in general developed, the types of tools expanded to include flat-ended and other shaped tools [11]. Fig. 1 shows the dimensions used to describe 3 main types of tools. Theadvantages of one type of tool over another have been a consistent area of research for some time, for example Kim and Park [12] and more recently Cawley et al. [13]. Tool diameter and tool type are two parameters studied in this literature review. The size and end-shape of the tool influence the mechanisms of the forming process. The size and shape of the area of contact between the tool and sheet can affect process aspects such as generated friction [14], observed forces [15], and pressure [16]. The tools can be made from different materials, and the interaction between the tool material, blank material and lubrica- tion influence the friction conditions seen during the process [17]. Currently there have been no published journal papers examining the effect of different tool materials on formability in SPIF, therefore it is not able to be included in this literature review. Toolpath parameters The toolpath used in SPIF can be the equivalent of a machining operation such as Z-level finishing, though the tool does not cut the material. The motion of the tool is defined by the same parameters used in machining operations. Feed rate is the velocity of the tool as it moves over the sheet, typically defined in mm/min. Step down is how far the tool presses into the sheet with each circuit. Spindle speed is how fast the tool spins, specified in rotations per minute (rpm). Toolpath parameters influence the generated friction by the movement and rotation of the tool [18], and the feed rate and step down define the deformation rate of the material. The relative rotation directions of the tool and toolpath determine the ‘milling mode’; either conventional or climb milling, to use the standard machining terms. If the tool and the toolpath are both moving clockwise or counterclockwise, it is conventional milling, and if they are rotating in different directions, it is climb milling. Climb milling is the most commonly used mode in SPIF, as the friction is reduced by the tool effectively ‘rolling’ over the sheet as it forms [19]. While cutting tools typically rotate in a clockwise direction, and therefore specifying toolpath direction might be enough for the reader to assume which milling mode is being used, it is not as thorough as defining conventional or climb (‘rolling’) milling as the utilised machining mode. Geometry The shape of the incrementally formed part affects the strains and therefore the formability of the material. The geometry is an aspect which is not covered in this literature review due to the complexity of analysing the many different shapes and dimensions used across the studied papers. In manufacturing a practical component, a draft angle analysis can be performed on the CAD model of the part to highlight which walls are steeper than a specified angle. Using the maximum wall angle for that material in the analysis will show whether there are any sections which may be too steep to form in a single SPIF pass. If there are no sections steeper than the permitted angle, it is likely that the part will succeed [20]. The curvature of the part, from straight walls to tight curves, affects the types of strains (plane, biaxial) developed during the process. For example strains from a conical frustum with 100 mm radius compared to the edge of a pyramidal frustum with 10 mm radius, as presented in Filice et al. Since the process was first developed, research has been conducted into modifications of the basic SPIF process. For example, many different methods of heating the workpiece havebeen explored. Duflou et al. [23] in 2007 used a laser to improve Fmax of TiAl6V4 sheets by more than 208. The same Titanium alloy was heated up to 400 8C with band heaters installed in the blank holder in Palumbo and Brandizzi [24], and an improvement in formability was observed. The use of electric current through the tool and the sheet has been explored in recent years, also applied to TiAl6V4 [25] and other materials such as AA6061-T6 [26] with resulting formability improvements. As this literature review studies process parameters for basic SPIF, parameters relevant to hot SPIF and electric SPIF are not examined. This work Research question What does the literature say about the effects of SPIF process parameters on formability? Hypothesis Each parameter has an optimal operating range which is a function of other parameters. They are interdependent in various combinations. This literature review is undertaken as a ‘systematic quantita- tive literature review’. This type of literature review is defined in Pickering and Byrne [27]. The process has been tested by multiple students and researchers, and produces repeatable and high quality results. This technique is highly applicable to the area of SPIF parameters due to the quantitative nature of the data input, and as will be seen in the tabulated results, allows effective comparisons of parameter values between multiple papers. The selected parameters that have been studied in this review are universal to every single pass SPIF process, and more specialised processes such as applying electric current or external heat are not addressed. Many SPIF papers have been published in the area of formability, however the inclusion criteria highlighted below are used to select a high quality collection of papers that are a good representation of the wider field. Details of the process steps as they relate to this literature review are shown below. Formability in single point incremental forming. 43 中文翻译 单点增量成形过程中成形性的研究现状 单点增量成形（SPIF）是一种用片材制造零件的方法，具有很少或没有定 制工具和其他通用装置的优点[1]。 这使其成为在投资冲压模具或一次性定制 部件之前生产钣金原型部件的理想选择。 SPIF 是一种增量成型（ISF），这是一类包括旋压和剪切成型的工艺[2]。 SPIF 比诸如能够形成不对称形状的旋转方法具有优势。在 2005 年的论文中，Jeswiet 等人 [3]成功地将当时所有的知识综合起来，并将其综合成为对不对称 ISF 过程 的进展和现状进行综合评述。 自那时起的十年研究要求对 SPIF 的进展和理解 进行更新审查，包括 2008 年首次探索的增量成形聚合物片[4]。 本文包括对单点增量成形的文献进行回顾，特别介绍影响成形过程中材料 成形性的工艺参数。 组织调查结果将有助于创建直观的参数指南和说明，以便 将来用 SPIF 研究和制造真实组件。 虽然商业和工业 SPIF 组件过去已经制造出来，但它们可能非常复杂，以至 于“试错”成为最可行的开发技术，因为使用 FEA（有限元分析）的计算过于 昂贵。 因此，一个重大挑战是如何使用比试验和错误更复杂的方法将其发展成 为工业过程。 这篇文献综述的目的是收集实验论文的相关数据并得出最大化 SPIF 材料成 形性的结论。SPIF 的其他方面未在本文中进行系统的介绍，它们正在形成力量， 表面质量，几何精度以及由此产生的材料属性。 成形性通常通过找出材料在失效前形成的最大壁角（Fmax）[5]与水平面之 间的关系进行量化。 通常使用简单的形状，例如圆锥或金字塔来确定该最大壁角。可以形成多 个部件，每个部件都具有比先前更陡的壁角，直到部件断裂[6]。 另一种选择是壁角从浅到陡变化的形状，例如 Hussain 等人 2007 年报道的 可变壁角圆锥截头体（VWACF）。 [7]。如果使用这部分，只需要一个测试来 确定发生故障的墙角。在同一篇论文中，Hussain et al。 [7]比较了 VWACF 的结 果和直墙试验的结果，发现后者高估了 Fmax 由于其较高的天气而低于 4％。因 此，如果直壁部分需要确切的骨折壁角度，则 VWACF 结果应进一步用锥形或锥 形平截头体进行测试。任何可成型性测试，但是，如果重复准确，应该给出一 致的结果，以便可以确定过程参数的一般影响。 “结果与讨论”一节中进一步 解释了总体效应，该文献提供了该文献综述中分析的数据。 在 SPIF 中已经使用了许多不同的材料，包括各种金属[3]，聚合物片材[4] 和其他片材材料，如夹层板[8]，其中具有广泛的可成形性。该评论不会检查特 定材料的成形性限制，而是将其列入参数分析中，以便可以在相同材料（例如 PVC 或 AA3003-O）之间进行实验对比。材料类型可以被视为选择所有其他参数 的基础。 未变形材料坯料的厚度是一个重要的参数，对 SPIF 工艺和最终部件具有显 着影响，特别是随着厚度的增加，片材变形所需的力变大[9]。最终，板料厚度 也是剪切成型正弦定律公式中的一个因素可以从初始厚度（ti）和水平角度（F） 计算部件的厚度（tf）。该方程是 tf = ti * sin（90 - F），并且已经证明对于单次 通过形成的 SPIF 零件是准确的[10]。 在这篇综述中，厚度的绝对值并不重要，因为独特的材料特性意味着一个 材料的 2 mm 薄片与 2 mm 不同材料的薄片表现不同[3]。已经研究了仅增加或 减小未变形空白的厚度的一般效果。 刀具参数 SPIF 中用于使纸张变形的工具或冲头传统上属于两种类型之一。 首先是一个坚固的半球形工具[2]，其次是一个带球轴承的工具，允许它在板上 自由滚动[6]。随着 SPIF 和增量成形技术的发展，一些工具已经扩展到包括端部 和其他形状的工具[11]。图 1 显示了用于描述 3 种主要类型工具的尺寸。一种 工具相对于另一种工具的优点是一段时间内的一致研究领域，例如 Kim 和 Park [12]以及最近的 Cawley 等人。 [13]。刀具直径和刀具类型是这篇文献综述中研 究的两个参数。 工具的尺寸和端部形状影响成形过程的机制。工具和片材之间接触面积的 大小和形状可能会影响过程方面，如产生的摩擦力[14]，观察力[15]和压力[16]。 刀具可以由不同的材料制成，并且刀具材料，坯料和润滑剂之间的相互作 用影响过程中所见的摩擦条件[17]。目前还没有关于不同工具材料对 SPIF 可成 形性影响的发表期刊论文，因此它不能被纳入本文献综述。 刀具路径参数 SPIF 中使用的刀具路径可以等同于 Z 级加工等加工操作，尽 管刀具不切割材料。刀具的运动由加工操作中使用的相同参数确定。进给速度 是刀具在纸张上移动时的速度，通常以毫米/分钟为单位。逐步减少工具在每个 电路中压入纸张的距离。主轴转速是指工具旋转的速度，以每分钟转数（rpm） 表示。 刀具路径参数通过刀具的运动和旋转来影响产生的摩擦力[18]，进给速率 和降低速度决定了材料的变形速率。 刀具和刀具路径的相对旋转方向决定了'铣削模式';无论是传统还是爬坡铣 削，都要使用标准加工条件。如果刀具和刀具路径都是顺时针或逆时针移动， 那么是传统铣削，如果他们正在以不同方向旋转，那就是爬铣。攀爬铣削是 SPIF 中最常用的模式，因为工具在形成时有效地“滚动”在工作台上，从而减少了 摩擦[19]。虽然切削刀具通常以顺时针方向旋转，因此指定刀具路径方向可能 足以让读者假设正在使用哪种铣削模式，但并不像定义常规或爬升（'滚动'）铣 削那样彻底，因为所用的加工模式。 几何图形增量成形零件的形状影响应变，从而影响材料的成形性。由于分 析研究论文中使用的许多不同形状和尺寸的复杂性，几何学是本文献综述中未 涉及的一个方面。 在制造实用部件时，可以在部件的 CAD 模型上执行拔模角度分析，以突出 显示哪些壁面比特定角度更陡。在分析中使用该材料的最大壁角将显示是否有 任何部分可能太陡，无法在单个 SPIF 通道中形成。如果没有比允许的角度更陡 峭的部分，则部件很可能会成功[20]。部件的曲率从直壁到紧密曲线影响过程 中形成的应变类型（平面，双轴）。例如 Filice 等人所介绍的圆锥截头圆锥体 的应变，其半径为 100 毫米，而圆锥体的圆锥体的边缘为 10 毫米半径。 实验参数由于该过程是第一次开发的，因此对基本的 SPIF 过程进行了修改 研究。例如，已经探索了许多不同的加热工件的方法。杜弗欧等人。 [23]在 2007 年使用激光将 TiAl6V4 片材的 Fmax 提高了 208 以上。同样的钛合金被加热到 400℃，带式加热器安装在坯料上持有人 Palumbo 和 Brandizzi [24]，并观察到成 形性的改善。通过刀具和片材的电流的使用近年来已经被探索，也被应用于 TiAl6V4 [25]和其他材料，如 AA6061-T6 [26]，从而提高了成形性。由于这篇文 献综述研究了基本 SPIF 的工艺参数，与热 SPIF 和电 SPIF 相关的参数未被检查。 这项研究的问题文献中关于 SPIF 工艺参数对成形性影响的说法是什么？ 假设每个参数都有一个最佳的工作范围，它是其他参数的函数。它们以各 种组合相互依存。方法这篇文献综述是作为“系统的定量文献综述”进行的。 这种类型的文献综述被定义在 Pickering 和 Byrne [27]中。该过程已经过多名学 生和研究人员的测试，并产生可重复和高质量的结果。 由于数据输入的定量特性，该技术非常适用于 SPIF 参数区域，并且可以在 列表结果中看到，可以有效比较多篇论文之间的参数值。本评价中所选研究的 参数对于每次单程 SPIF 过程都是通用的，并且更多专门的过程（如应用电流或 外部热量）未得到解决。 许多 SPIF 论文已经发表在可成形性领域，但是下面强调的纳入标准被用来 选择高质量的论文集，这些论文可以很好地表达更广泛的领域。