面向管材的异型截面液压成形技术的研究

液压成形技术是液压传动与材料成形相结合的一门新技术,该技术综合了液压传动与材料成形技术的独特优点,具有宽广的发展前景。文章论述了管材异型截面液压成形的原理,成形特征分析和成形设备设计要点,旨在推动液压成形技术的发展。     

第一讲 装备再制造技术（八）

二、材料制备与成形一体化技术 材料制备与成形一体化技术与锻造、热处理、机械加工等技术不同,它是针对装备零部件再制造,实现零件修复部位成形和修复材料制备两个过程同时完成的各种再制造技术。材料制备与成形一体化技术是再制造工程先进技术。     

影响金属板材的冲压成形性能材料因素浅析

本文简要介绍了金属板料成形加工在制造业的地位及影响金属板材冲压成形性能因素,重点介绍了影响材料成形性能的成形极限及八个材料性能因素,说明了掌握金属板材冲压成形性能的重要性。     

《中国机械工程》材料数字化智能化成形专辑征文通知

正为传播材料数字化智能化成形的最近国际国内学术动态,促进学者、专家广泛交流本领域先进技术的发展与应用成果,《中国机械工程》将于近期策划出版材料数字化智能化成形专辑,聚焦于材料成形数字化智能化共性技术方向报道我国在该领域的最新研究成果与发展动态。一、专辑征文范围1.材料成形中的数字化与智能化产品设计2.材料成形CAD/CAPP/CAM/MES/PLM/ERP等技术3.成形过程仿真优化与集成计算材料工程4.成形工艺与产品质量的在线感知方法     

分段沉积雕铣成形工艺及材料研究

分段沉积成形是一种基于堆积成形和传统成形相结合的复合成形方法,同时具有了堆积成形的柔性和传统成形的高精度.工艺实现的前提是使支撑材料和工件材料满足严格的匹配关系,因此,材料研究成了该领域的一个重要研究方向.本文主要致力于寻找一种合适的材料,来满足该工艺加工需要.通过对环氧树脂、乙二胺、金属粉末三种材料采用正交实验的方法,并结合相关的检测技术,最终得出适合分段沉积成形工艺的材料.     

背压对5083铝合金超塑胀形性能的影响

通过三组对比试验分析了背压对于5083铝合金锥形件成形性能的影响。实验结果表明,背压可以有效提高材料的成形极限;而在极限状态下,背压胀形的应变也大于无背压时材料的应变。同时,实验发现,3MPa背压下材料的成形性能要好于1.5MPa背压下材料的成形性能。     

用于选区激光烧结的成形材料

根据选区激光烧结成形的特点,讨论了材料性能对成形工艺与零件性能的影响,重点分析了几类成形材料的性能参数与工艺控制因素。     

转向螺母多向联动加载成形工艺研究

转向螺母是汽车上复杂异形非圆齿形零件,结构形状复杂,需要多个方向产生变形,各部分变形量不同,成形难度大。在分析其结构形状特点和成形难点的基础上,提出了多向联动加载成形工艺。该工艺在成形过程中,各凸模加载顺序、速度、行程根据材料流动和充填情况进行联动控制,控制材料主动向需要的地方流动和填充,进而提高材料充填性和降低成形力。利用有限元软件对该工艺成形过程中的金属流动规律、材料填充状况、应力分布、成形力进行了数值模拟分析。对转向螺母的多向联动加载成形工艺和顺序加载成形工艺进行了对比分析,多向联动加载成形工艺比顺序加载成形工艺成形力降低了28%。对多向联动加载成形工艺进行了成形试验,成形出的转向螺母充填饱满,尺寸符合图纸要求,未出现锻造缺陷,并进行了小批试制。试验结果表明该工艺具有可行性和实用性。     

骨组织工程细胞载体框架的两种快速成形新工艺

采用纳米羟基磷石灰石／胶原自组装材料，同时在成形过程中加入聚左旋乳酸以改善的成形性能，开发了两种新的制备骨组织工程细腻载体框架结构的快速成形工艺：T（组织工程材料）＋F（框架成形材料）成形工艺和低温喷射成形工艺。这两种工艺实现了材料的精确堆积，能成形200－500μm的可控大孔隙和孔隙梯度结构，获得理想的形态参数。     

薄饼类锻件辗扩成形

如图1所示的锻件产品,可以通过不同种类锻造设备予以锻造成形,从综合考虑锻件成本来看,材料利用率、模具及动能的多少决定了锻件的利润多少,模锻成形中要去除飞边及连皮,材料利用率在75％以上;辗扩成形中只在制坯中去除连皮,材料利用率可达到90％以上。在生产中辗扩成形较模锻成形在模具投入及动能消耗上均减少20％以上,辗扩成形明显较模锻成形有优势。本文中仅针对辗扩设备生产薄饼类锻件产品的成形予以分析。     

形状沉积制造及其应用

文章在分析了常规的快速原型制造所存在的缺点后，详细地介绍了形状沉积制造区别于快速原型制造过程中单纯地添加材料的过程——添加／去除零件材料方法，正是由于这一差别使得该方法制造的零件精度不受分层厚度的影响，并且可以采用多种材料制造零件。介绍了形状沉积法的具体工艺过程、可采用的材料沉积工艺方法、沉积制造的设备构成、分层技术、特点及基于形状沉积制造的新方法——模具形状沉积制造，最后介绍了形状沉积制造在功能零件、模具及预装配机构快速制造中的应用实例。     

Micro Electrical Discharge Machining Deposition in Air for Fabrication of Micro Spiral Structures

Micro electrical discharge machining(EDM) deposition process is a new micro machining method for fabrication of metal micro structures. In this process, the high level of tool electrode wear is used to achieve the metal material deposition. Up to now, the studies of micro EDM deposition process focused mainly on the researches of deposition process, namely the effects of discharge parameters in deposition process on the deposition rate or deposition quality. The research of the formation of micro structures with different discharge energy density still lacks. With proper conditions and only by the z-axis feeding in vertical direction, a novel shape of micro spiral structure can be deposited, with 0.11 mm in wire diameter, 0.20 mm in outside diameter, and 3.78 mm in height. Then some new deposition strategies including angular deposition and against the gravity deposition were also successful. In order to find the forming mechanism of the spiral structures, the numerical simulation of the transient temperature distribution on the discharge point was conducted by using the finite-element method(FEM). The results show that there are two major factors lead to the forming of the spiral structures. One is the different material removal form of tool electrode according with the discharge energy density, the other is the influenced degree of the movement of the removed material particles in the discharge gap. The more the energy density in single discharge is, the smaller the mass of the removed material particles is, and the easier the movements of which will be changed to form an order tendency. The fine texture characteristics of the deposited micro spiral structures were analyzed by the energy spectrum analysis and the metaliographic analysis. It shows that the components of the deposited material are almost the same as those of the tool electrode. Moreover the deposited material has the brass metallic luster in the longitudinal profile and has compact bonding with the base material. This research is useful to understand the micro-process of micro EDM deposition better and helpful to increase the controllability of the new EDM method for fabrication of micro structures.     

电火花沉积电极材料过渡机制及规律

利用旋转电极电火花沉积装置,在Q235钢表面逐层沉积1至6层铜合金涂层,计算分析了每层沉积厚度、过渡形态、表面和截面形貌,探讨了电火花沉积电极材料的过渡机制、形态和规律。结果表明：工件和电极的质量变化曲线相似,随着沉积层数的增加,质量变化量减少直至趋于稳定;沉积层以熔融物质团（液态、半固态）的形态过渡沉积生成,电极与工件材料在沉积层与基体界面处互相渗透,生成厚约20~30 μm的过渡层;工件材料对沉积层的稀释作用主要发生在过渡物质团结合处,对其内部影响极小,且随着沉积层数的增加而减小,沉积层由多层电极材料覆盖叠压构成;随着沉积层数的增大,放电能量利用率降低,单次沉积厚度降低,电极对沉积表面的磨削涂覆作用增大,电极材料沉积率有所下降。     

Modeling of the geometry built-up by coaxial laser material deposition process

Coaxial laser material deposition (also known as laser-cladding process) is being used for selective material deposition on complex parts since the 1990s. Its main applications include coatings, rapid manufacturing, or high added value part repairing. The main advantages of the coaxial laser-cladding process are the high-quality bonding interface between added and substrate material, excellent mechanical behavior, and high precision of the resulting geometry in comparison with conventional welding processes. Moreover, the laser-cladding process involves low-heat input, which leads on minimum thermal distortions and reduced heat-affected zone. Thus, high responsibility components like aeronautic turbine parts, tooling for die and mold industry or medical implants, among others, can be processed with laser cladding. This paper presents a laser material deposition process model for the estimation of the geometric characteristics of added material layers, including the prediction of the 3D shape of single and multiple clads and considering overlapping effect, which is the common situation on industrial applications. The model only needs the typical process parameters as the laser power, substrate material, powder material and size, etc. The model has been applied to different laser material deposition strategies and validated for two different materials (AISI D2 and Inconel 718) by experimental testing, obtaining good agreement between estimated and measured values. Finally, a case study for a turbine engine fixture is presented as a possible application. Therefore, the proposed algorithm can be applied for estimating the resulting geometry of the laser-cladding process and predict the optimum laser-cladding strategy, number of layers, and distance between layers before programming the operation.     

Potential of cold gas dynamic spray as additive manufacturing technology

In this paper, the application of cold spray (CS) coating deposition technology as additive manufacturing technique is discussed. Absence of material melting during CS deposition permits to obtain deposits with low value of residual stresses and to preserve the phase composition of source material which is a very important advantage. In this paper, the latest developments in the field of cold spray such as micronozzle device and new multimaterial deposition approach permitting to significantly enlarge the potential of cold spray as additive manufacturing technology is discussed.     

Magnetic refinement of tips for magnetic force microscopy

Silicon cantilever probes with monolithically integrated tips are commercially available and are routinely used for atomic force microscopy (AFM). For such probes, amagnetic refinement of the silicon tip has been developed and results in a deposition of ferromagnetic material such as nickel or CrCoTa in the top area of the tip. The method consists of essentially three steps: (1) A broad-area sputter deposition of a ferromagnetic material; (2) a selective electron beam-induced carbon deposition at the top of the tip; (3) a broad-area ion-beam sputter etching, which removes the magnetic layer everywhere except underneath the carbon cap. The method allows to control the total amount and extension of the magnetic material left at the tip. It is applicable to all kinds of ferromagnetic materials which can be deposited as a thin layer by sputter deposition or evaporation. Experiments indicate that the method is reliable and improves the resolution of magnetic force microscopy (MFM). With such magnetically refined tips on silicon cantilevers, MFM measurements have been performed in contact mode as well as in dynamic and static noncontact modes. In this paper, the method for magnetic tip refinement is described and MFM measurements with these tips are presented.     

MICRO ELECTRICAL DISCHARGE MACHINING DEPOSITION IN AIR

A new deposition method is described using micro electrical discharge machining (EDM) to deposit tool electrode material on workpiece in air. The basic principles of micro electrical discharge deposition (EDD) are analyzed and the realized conditions are predicted. With an ordinary EDM shaping machine, brass as the electrode, high-speed steel as the workpiece, a lot of experiments are carried out on micro EDD systematically and thoroughly. The effects of major processing parameters, such as the discharge current, discharge duration, pulse interval and working medium, are obtained. As a result, a micro cylinder with 0.19 mm in diameter and 7.35 mm in height is deposited. By exchanging the polarities of the electrode and workpiece the micro cylinder can be removed selectively. So the reversible machining of deposition and removal is achieved, which breaks through the constraint of traditional EDM. Measurements show that the deposited material is compact and close to workpiece base, whose components depend on the tool electrode material.     

The Application of the Skipped Layer Interior Method and Higher Depostition Height to Accelerate Fabrication Speed of the Model Maker Rapid Prototyping System

The Model Maker (MM) process is one of the jet deposition rapid prototyping (RP) systems that delivers material through a jet and deposits the liquefied material onto a platform to build a physical model. The fabrication speed of the MM model is extremely low because of the low deposition rate and cutting operation. In order to accelerate the fabrication speed of the MM, the line pitch of the MM processing parameters was reconfigured to increase the deposition rate and, hence, increase the deposition height. The cutting operation of the MM removes almost half of the deposited material because of the requirements of model accuracy and layer thickness. In order to reduce the amount of the removed material, a skipped layer interior method was employed. The reconfiguration of the line pitch to increase deposition height enabled more interior layers to be skipped and, hence, less deposited material was removed. Therefore, the fabrication speed was significantly accelerated. The results show that the average model printing time saved was around 40% for all layer thicknesses, while the model accuracy and the layer thickness were still the same as in the original MM process.     

螺杆挤出塑化熔融沉积先进快速成形技术的探讨

为扩大熔融沉积快速成形技术的原材料选取范围,提高制品质量,简化生产工艺与降低企业的生产成本,提出新的快速原型制造技术--精密微型螺杆挤出塑化沉积快速成形技术.详细描述该技术的工作原理,介绍该设备的微型螺杆挤出机的螺杆和喷嘴;列举一些可用该方法加工的材料.     

Determination of layer thickness in direct metal deposition using dimensional analysis

Direct Metal Deposition (DMD) is a blown powder laser deposition process that can be used to quickly produce fully dense metallic parts and to repair or modify high-value components. This paper illustrates the use of dimensional analysis to develop a mathematical model for the control of layer deposition in DMD. A brief explanation of the material deposition process is presented and the factors affecting the metal deposition is identified so that they can be used in modeling the height of the metal deposited. The validity of the generalized model is verified from experimental data of H13 steel and Ti material and it is found in good agreement with experimental findings.