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1、 毕业设计(论文)外文资料翻译系部： 机械工程系 专 业： 机械工程及自动化 姓 名： 学 号： (用外文写)外文出处：International Conference on Spray Deposition and Melt Atomization附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语：译文较为准确地表达了原文的概念和主题，叙述较清晰，语句较通顺。翻译质量良。 签名： 年 月 日注：请将该封面与附件装订成册。附件1：外文资料翻译译文喷射成形加工对于注射成型和冲压成型模具的应用摘要快速凝固加工工艺（RSP）是一种适合于生产注塑模具和冲压模具的喷射成形技术。这种方法把快速凝
2、固加工和网状材料加工结合在一个单步执行。这种喷射堆积成型的方式取代了常规模具制造中使用的昂贵的机械加工方法，并减少了周转时间。此外，快速凝固抑制碳化物的析出和增长、促使铁素体工具钢被人工老化，为代替传统热处理提供了独特的益处。喷射成形工具钢H13描述了热处理过程中的材料性能和微观结构的转变。引言注塑模具和冲压模具，以及相关的工具常被用来制造我们每天都在家里或工作中使用的塑料和金属部件。这一加工出所希望的零件形状（模芯和型腔）的过程包含锻制工具钢或者金属铸件毛坯，增加冷却通道、排气孔和其他机械性能，接着是磨。许多注塑模具和冲压模具需进行热处理（奥氏体化/淬火/回火）以改善金属性能，接着是最后的研
3、磨和抛光以实现期望的效果1。模具的传统制造方法是非常昂贵和费时的，因为：1.每一个定制的产品，都反映了所需零件的形状和结构。2.用于制造模具的材料是难以被机械加工的。对于长期生产来说，工具钢产业是其骨干产业。加工工具钢是资本密集型设备，因为个别加工步骤往往需要专门的加工设备。3.机械加工必须精确。许多个体零件必须正确装配和校正才能使最终产品正常运行。注塑模具的费用因规模大小和复杂程度，从大约1万美元到30万美元以上不等，并有3到6个月的制造周期。零件检查和资格认证可能需要额外的3个月。大型传输机器的压铸模具和制造汽车车身面板的金属板冲压模具成本可能会超过100万美元。制造周期通常大于40周。每
4、年一个大型汽车公司投资约10亿美元在制造部件进入其新的轿车和卡车生产线上。喷射成形为降低成本和减少制造时间提供了巨大的可能性，省去了很多如加工、研磨、抛光的单步工序。另外，喷射成形提供了强有力的手段来抑制合金元素的凝固和碳化物的形成，在大多数铁素体工具钢中都能创造有利的亚稳相。因此，相对较低的温度处理沉淀硬化可用于制造特定性能的金属，如硬度，韧性，抗疲劳强度和刚度。本文介绍了喷射成形技术对于生产H13工具钢的注塑模具和冲压模具的应用，以及低温热处理所带来的好处。快速凝固加工工艺快速凝固加工工艺（RSP），是一种适合生产注塑模具和冲压模具的喷射成形技术2-4。这种方法把快速凝固加工和网状材料加工
5、结合在一个单步执行。从CAD软件到高精度工具钢所使用的一个合适的快速原型（RP）技术解释了一般概念上所涉及模具设计转换，如立体平板印刷。一般是用氧化铝或熔融石英把一个模板转变为一个浇注陶瓷。紧接着是用喷射成形喷一层厚厚的工具钢（或其它合金）沉积物在模板上的方式获得所需的形状、表面纹理和细节。由此合成的金属块冷却到室温与模具分离。通常，沉积物的外表面被加工成方形，在一个控股块中能够被用来作为插入物，如MUD结构5。在一个机器工作的情况下，加工总周转时间大约是3天。注塑模具和冲压模具的这种生产方式已被用于塑料注塑和冲压模具的原型和生产运行。快速凝固加工工艺一个很大的好处是，它让制造注塑模具和冲压模
6、具的过程成为设计周期前期的一部分。真正的原型零件用相同的生产加工计划可以被制成预定形状、尺寸和性能。若零件是合格的，它能像普通零件一样被用于生产加工。使用数字化资料库和RP技术可以很容易的修改设计上的内容。实验步骤氧化铝基陶瓷（Cotronics7806）是浆体通过硅橡胶模具或格式机冷冻模具铸造的。完成后，陶瓷模型脱离模具，在干燥室烘干并冷却到室温。H13工具钢是由在内部设计和建造的温度约100C、压力由有工作台刻度的收敛/发散喷雾嘴控制的氮气保护层中诱导融化的。喷雾装置在惰性气体中能最大限度地减少漂浮状态的氧化液滴，因为它们存放的加工模式比率大约是200公斤/小时。气体到金属的质量流量比大约
7、是0.5。对于延伸性和硬度的要求，喷射成形材料用电火花加工来去除表面0.05毫米厚的热影响区。在没有氮气的火炉中对样品进行热处理。为防止脱碳，每个涂有氧化硼的样品都放置在一个密封的金属箔包内。把样品放在400至700C的温度范围内人工老化，随后空冷。常规热处理H13钢的是在1010C的温度持续30分钟使它奥氏体化，随后空冷，再在538C的温度两次回火。在室温下，微硬度测量使用的是平均每10微刻度读数的M型维氏硬度测试仪。工具钢被腐蚀（3硝酸浸蚀液）的微细结构的光学评估使用奥林巴斯的PME-3金相显微照片和安瑞1830年电子扫描显微镜。相成分通过能量分散光学（EDS）分析。超范围喷涂粉末的分析由
8、麦奇克系列微粒分析器在来筛去200微米的粉末样品覆盖的粗糙表面。样品密度由利用阿基米德原理工作的梅特勒天平（型号AE100）的排水量来测试。用INEEL（国家工程与环境实验室）开发的一维计算机章程用来评价多相流在自由射流喷嘴的表现。该章程的基本数值技术解决了稳态气流场通过合适网格，全气动和强力耦合之间的水滴和运输气体的保守变量的方法和采用液滴相的拉格朗日公式。液态金属喷射系统耦合的气体力学，包括热传递和摩擦在内。该章程还包括一个允许液滴冷却和升温的非平衡凝固模型。该章程用于描述用射流喷嘴喷出的气体和雾化液滴的温度和速度变化情况。结果与讨论喷射成形是一个有效的快速制造技术，它让工具钢注塑模具和冲
9、压模具的生产变得简单。每个零件都是用快速原型机器通过陶瓷模板喷射成形的。粒子和气体的状态图1给出了喷射H13工具钢的粒子聚集频率和累积频率分布图。中央块状直径被确定的56微米为插补尺寸的50的累积频率。这些面积平均直径和体积平均直径是分别被计算出的53微米和139微米。几何标准偏差是1.8，sd=(d84/d16)1/2 ，d84和d16是粒子直径相应的84和16的累积量。图1 喷射H13工具钢的粒子聚集频率和累积频率分布图2给出了在射流喷嘴里多相流场速度的计算结果（图2a），和H13工具钢的凝固体分数线（图2b）。气体速度增长至激震前沿位置时会急剧下降，最终在喷嘴外成倍衰退。小水滴很容易被速
10、度场干扰，在喷嘴内加速喷嘴外减速。在达到其终级速度后，较大的水滴（150微米）因为其较大的动力受流场干扰较小。众所周知，目前的喷射成形高速粒子在喷嘴（103-106开/秒）和大部分沉积物（1-100开/分）的冷却速度7。大多数粒子在喷射中经历了复辉而造成的凝固体分数大约是0.75。计算出的从喷嘴喷出的或小（30微米）或大（150微米）的凝固体分数，如图2b。图2 气体和微粒在射流喷嘴里多相流场。(a)速度分布图 (b)凝固体分数线喷射成形沉积这种高温提取率模式降低了因腐蚀而影响工具表面质量。这是相对灵活的，浇注陶瓷材料的模式将取代难以令人满意的常规金属铸造过程。通过合适的加工条件，喷射成形模具
11、模式可以制造出优质的表面质量。表面粗糙度因成型表面的质量而定。商业浆体生产的适合许多成型应用的铸造陶瓷的表面粗糙度大约是1微米。沉积工具钢在钢化玻璃上产生的定向反射面抛光粗糙度大约是0.076微米。在初电流阶段，一个普通的机床来重复性空间喷射成形模具大约是0.2。化学性质H13工具钢的化学性质要求是使材料承受温度、压力、磨损和热循环等要求苛刻的应用，如冲压模具。这是最流行的冲压模具合金也是全球第二受欢迎的塑料注塑工具钢。这种钢以低含碳量（0.4）来提高韧性，以中等含铬量（5）来提供良好的抗高温软化性，以1的硅含量来改善抗高温氧化性，以少量钼和钒（约1）形成稳定的碳化物来提高耐磨性8。喷射成形前
12、后对H13工具钢的成分分析。表1给出的结论，说明在合金补充后没有显著的变化。表1 H13工具钢的组成 化学成分 C Mn Cr Mo V Si Fe 常规H13钢 0.41 0.39 5.15 1.41 0.9 1.06 Bal. 喷射成形H13钢 0.41 0.38 5.10 1.42 0.9 1.08 Bal. 微观结构在H13的工具钢中发现的碳化物的大小、形状、类型和分布是取决于加工方法和热处理的。一般的商业钢，机械厂会在使用之前退火处理和热处理（奥氏体化/淬火/回火）。典型的奥氏体化温度大约是1010C，在空气或油中淬火，并在540至650C仔细回火两次或三次，以获得与要求相符合的硬度
13、、抗疲劳强度和韧性。商业用的锻造铁素体工具钢因为钢铁厂的铸块慢慢冷却形成粗糙碳化物而不能被沉淀硬化。与此相反，快速凝固的H13工具钢因为合金增加的原因在很大程度上解决了这个问题，并更均匀地分布于模型9-11。其性能可以被人工老化或常规热处理改变。人工老化的一个好处是它绕开常规热处理过程中具体的容积变化而导致的工具变形的发生。这些具体的容积的变化发生在从奥氏体向铁素体转为回火马氏体的模型转换阶段，必须在模具设计的初期说明。然而，不是总能得到可靠预测的。补充的这部分，从设计和生产的角度看可能是可取的，经常不包括像材料在淬火中奥氏体化或变形时有大幅衰退的趋势。因为它没有相变，喷射成形工具钢不遵守人工
14、老化期间的工具失真。参 考 文 献1 R. G. W. Pye, Injection Mould Design, John Wiley & Sons, NY, p. 14, 1989.2 Rapid Prototyping & Tooling State of the Industry - 1998 Worldwide Progress Report, Terry T. Wohlers, Wohlers Associates, Inc., p. 22, 1998.3 Kevin M. McHugh, “Fabrication of Tooling Inserts Using RSP Tooli
15、ng Technology,” Proceedings of Moldmaking 99 Conference, Communication Technologies, Inc. Columbus, OH, May, 1999, p. 383.4 B. Hewson, J. Folkestad, and K. M. McHugh, “Qualifying Rapid Solidification Process Tooling: Justifying Cutting Edge Technology,” Proceedings of Rapid Prototyping and Manufactu
16、ring 99 Conference, The Society of Manufacturing Engineers, Dearborn, MI, April, 1999, p.75.5 Master Unit Die Quick-Change Systems, Greenville, MI6 Cotronics Corporation, Brooklyn, NY.7 E. J. Lavernia and Y. Wu, Spray Atomization and Deposition, John Wiley and Sons, New York, NY, p. 291, 1996.8 Tool
17、 Materials, ed. J. R. Davis, ASM International, Materials Park, OH, P.139, 1995.9 K. M. McHugh, “Microstructure Transformation Of Spray-Formed H13 Tool Steel During Deposition and Heat Treatment,” Solidification 1998, Edited by S. P. Marsh, J. A. Dantzig, R. Trivedi, W. Hofmeister, M. G. Chu, E. J.
18、Lavernia, and J.-H Chun, The Minerals, Metals, & Materials Society, P. 427, 1998.10 Kyeong Ho Baik, Eon-Sik Lee, Woo-Jin Park, and Sangho Ahn, “Formation of Eutectic Carbides in Spray Cast High Speed Steel,” Proceedings of the Third International Conference On Spray Forming, Cardiff, UK p. 251, (199
19、6).11 K. Bhargava and A. N. Tiwari, “Effect of Rapid Solidification and Heat Treatment on D2 Tool Steel,” Internat. J. Rapid Solidification, 7, 51 (1992).附件2：外文原文Spray-Formed ToolingFor Injection Molding and Die Casting ApplicationsAbstractRapid Solidification Process (RSP) Tooling is a spray formin
20、g technology tailored for producing molds and dies. The approach combines rapid solidification processing and net-shape materials processing in a single step. The ability of the sprayed deposit to capture features of the tool pattern eliminates costly machining operations in conventional mold making
21、 and reduces turnaround time. Moreover, rapid solidification suppresses carbide precipitation and growth, allowing many ferritic tool steels to be artificially aged, an alternative to conventional heat treatment that offers unique benefits. Material properties and microstructure transformation durin
22、g heat treatment of spray-formed H13 tool steel are described.IntroductionMolds, dies, and related tooling are used to shape many of the plastic and metal components we use every day at home or at work. The process involves machining the negative of a desired part shape (core and cavity) from a forg
23、ed tool steel or a rough metal casting, adding cooling channels, vents, and other mechanical features, followed by grinding. Many molds and dies undergo heat treatment (austenitization/quench/temper) to improve the properties of the steel, followed by final grinding and polishing to achieve the desi
24、red finish 1.Conventional fabrication of molds and dies is very expensive and time consuming because: Each is custom made, reflecting the shape and texture of the desired part. The materials used to make tooling are difficult to machine and work with. Tool steels are the workhorse of industry for lo
25、ng production runs. Machining tool steels is capital equipment intensive because specialized equipment is often needed for individual machining steps. Tooling must be machined accurately. Oftentimes many individual components must fit together correctly for the final product to function properly.Cos
26、ts for plastic injection molds vary with size and complexity, ranging from about $10,000 to over $300,000 (U.S.), and have lead times of 3 to 6 months. Tool checking and part qualification may require an additional 3 months. Large die-casting dies for transmissions and sheet metal stamping dies for
27、making automobile body panels may cost more than $1million (U.S.). Lead times are usually greater than 40 weeks. A large automobile company invests about $1 billion (U.S.) in new tooling each year to manufacture the components that go into their new line of cars and trucks.Spray forming offers great
28、 potential for reducing the cost and lead time for tooling by eliminating many of the machining, grinding, and polishing unit operations. In addition, spray forming provides a powerful means to control segregation of alloying elements during solidification and carbide formation, and the ability to c
29、reate beneficial metastable phases in many popular ferritic tool steels. As a result, relatively low temperature precipitation hardening heat treatment can be used to tailor properties such as hardness, toughness, thermal fatigue resistance, and strength. This paper describes the application of spra
30、y forming technology for producing H13 tooling for injection molding and die casting applications, and the benefits of low temperature heat treatment.RSP ToolingRapid Solidification Process (RSP) Tooling, is a spray forming technology tailored for producing molds and dies 2-4. The approach combines
31、rapid solidification processing and netshape materials processing in a single step. The general concept involves converting a mold design described by a CAD file to a tooling master using a suitable rapid prototyping (RP) technology such as stereolithography. A pattern transfer is made to a castable
32、 ceramic, typically alumina or fused silica. This is followed by spray forming a thick deposit of tool steel (or other alloy) on the pattern to capture the desired shape, surface texture and detail. The resultant metal block is cooled to room temperature and separated from the pattern. Typically, th
33、e deposits exterior walls are machined square, allowing it to be used as an insert in a holding block such as a MUD frame 5. The overall turnaround time for tooling is about three days, stating with a master. Molds and dies produced in this way have been used for prototype and production runs in pla
34、stic injection molding and die casting.An important benefit of RSP Tooling is that it allows molds and dies to be made early in the design cycle for a component. True prototype parts can be manufactured to assess form, fit, and function using the same process planned for production. If the part is q
35、ualified, the tooling can be run in production as conventional tooling would. Use of a digital database and RP technology allows design modifications to be easily made.Experimental ProcedureAn alumina-base ceramic (Cotronics 780 6) was slurry cast using a silicone rubber master die, or freeze cast u
36、sing a stereolithography master. After setting up, ceramic patterns were demolded, fired in a kiln, and cooled to room temperature. H13 tool steel was induction melted under a nitrogen atmosphere, superheated about 100C, and pressure-fed into a bench-scale converging/diverging spray nozzle, designed
37、 and constructed in-house. An inert gas atmosphere within the spray apparatus minimized in-flight oxidation of the atomized droplets as they deposited onto the tool pattern at a rate of about 200 kg/h. Gas-to-metal mass flow ratio was approximately 0.5.For tensile property and hardness evaluation, t
38、he spray-formed material was sectioned using a wire EDM and surface ground to remove a 0.05 mm thick heat-affected zone. Samples were heat treated in a furnace that was purged with nitrogen. Each sample was coated with BN and placed in a sealed metal foil packet as a precautionary measure to prevent
39、 decarburization.Artificially aged samples were soaked for 1 hour at temperatures ranging from 400 to 700C, and air cooled. Conventionally heat treated H13 was austenitized at 1010C for 30 min., air quenched, and double tempered (2 hr plus 2 hr) at 538C.Microhardness was measured at room temperature
40、 using a Shimadzu Type M Vickers Hardness Tester by averaging ten microindentation readings. Microstructure of the etched (3% nital) tool steel was evaluated optically using an Olympus Model PME-3 metallograph and an Amray Model 1830 scanning electron microscope. Phase composition was analyzed via e
41、nergy-dispersive spectroscopy (EDS). The size distribution of overspray powder was analyzed using a Microtrac Full Range Particle Analyzer after powder samples were sieved at 200 m to remove coarse flakes. Sample density was evaluated by water displacement using Archimedes principle and a Mettler ba
42、lance (Model AE100).A quasi 1-D computer code developed at INEEL was used to evaluate multiphase flow behavior inside the nozzle and free jet regions. The codes basic numerical technique solves the steadystate gas flow field through an adaptive grid, conservative variables approach and treats the dr
43、oplet phase in a Lagrangian manner with full aerodynamic and energetic coupling between the droplets and transport gas. The liquid metal injection system is coupled to the throat gas dynamics, and effects of heat transfer and wall friction are included. The code also includes a nonequilibrium solidi
44、fication model that permits droplet undercooling and recalescence. The code was used to map out the temperature and velocity profile of the gas and atomized droplets within the nozzle and free jet regions.Results and DiscussionSpray forming is a robust rapid tooling technology that allows tool steel
45、 molds and dies to be produced in a straightforward manner. Each was spray formed using a ceramic pattern generated from a RP master.Particle and Gas BehaviorParticle mass frequency and cumulative mass distribution plots for H13 tool steel sprays are given in Figure 1. The mass median diameter was d
46、etermined to be 56 m by interpolation of size corresponding to 50% cumulative mass. The area mean diameter and volume mean diameter were calculated to be 53 m and 139 m, respectively. Geometric standard deviation, sd=(d84/d16) , is 1.8, where d84 and d16 are particle diameters corresponding to 84% a
47、nd 16% cumulative mass in Figure 1.Figure1. Cumulative mass and mass frequency plots of particles in H13 tool step sprays.Figure2 gives computational results for the multiphase velocity flow field (Figure 2a), and H13 tool steel solid fraction (Figure2b), inside the nozzle and free jet regions. Gas velocity increases until reaching the location of the shock front, at which point it precipitously decreases, eventually decaying exponentially outside the nozzle. Small droplets are easily perturbed by the velocity field, accelerating inside the nozzle
