59—1-1铁黄铜筒形件热反挤压表面重皮与气泡缺陷的分析

分析了59—1-1铁黄铜热反挤压筒形件表面重皮、气泡等缺陷与工艺参数之间的关系及缺陷产生的机理,提出了选择合理的加热温度、挤压速度,减少饼料表面缺陷,合理润滑,以及严格执行工艺操作规程等预防措施,消除了制件缺陷。     

基于FDM的工艺品模型制作

传统加工方法无法满足多数工艺品模型制作周期短、单件小批量的要求。而FDM快速成形技术以其制作速度快、无污染、成本低等特点,可以解决上述问题。针对大雁塔模型在制作过程中由于加工工艺参数、加工的设备等因素产生的制件冷却收缩变形以及开裂等缺陷进行分析。提出了减小制件冷却收缩变形的方案,优化了加工工艺参数,从而提高了制件的质量和制作的效率。     

汽车注塑件典型缺陷及优化方法

随着汽车行业生产工艺的不断创新和突破,有更多的新型材料运用到零部件的制造上,对于机车在塑料零部件制造,通过改进传统的工艺,采用注射成型技术,生产更轻型、高效能的塑料制件。但是汽车注塑件在塑件成型的过程中,因为设备和工艺上的影响因素下,在实际制件中出现制件在设计结构上,以及材料质量上的不合理而影响汽车生产质量,本文通过阐述生产中常见的制件缺陷,并结合实际生产需要提出合理建议。     

聚酰胺工程塑料拖拉机零件生产工艺分析

介绍了聚酰胺工程塑料拖拉机零件的生产工艺以及制件常见缺陷的成因。     

增材制件内部缺陷埋藏深度的激光超声定量检测

针对增材制件内部缺陷检测，提出一种内部缺陷埋藏深度的定量检测方法。对用激光超声无损检测技术接收到的信号采用小波包分解技术进行分离并提取信号中的超声纵波，解决了超声表面波和纵波耦合影响时域特征提取的问题。根据检测过程中经过缺陷的纵波声程的变化，实现了精锻试块内部缺陷埋藏深度的定量检测，检测结果的相对误差为1.81%。在原检测方法的基础上增加异常点滤除算法，并应用于增材制件内部缺陷的检测，检测结果的相对误差为1.76%。     

ZG15Cr1Mo1V阀门铸件的补焊

分析了ＺＧ１５Ｃｒ１Ｍｏ１Ｖ阀门铸件经机加工后出现缺陷的原因，介绍了对缺陷实施补焊的准备、施焊及检查等工艺过程，总结了对合金钢阀门铸件铸造缺陷在机加工后期补焊的实用方法和操作经验。     

镍合金激光直接烧结成形制件显微结构及微观缺陷

利用自行研制的激光直接烧结快速成形系统进行了镍合金激光直接烧结成形试验，获得了具有复杂三维形状的镍合金样件；讨论了激光直接照射下镍合金材料的熔凝过程及微观结构特征。研究表明，烧结过程为不完全液相烧结。金属材料系统中添加铜可有效地抑制球化效应，改善制件内部存在的微观缺陷；制件内部单一层面微观组织呈枝晶和等轴晶两种组织不均匀分布，此两种组织形态沿制件堆积方向交替重复出现。     

一例快速成型制件缺陷的解决

通过分析一个SLA快速成型机制作过程中出现的制件变形、起皮问题,探讨了引起制件变形、起皮的原因,通过调整成型机相关制作参数解决了制件变形、起皮的问题.     

ZG1Cr5MoR阀门铸件的补焊

分析了ZG1Cr5MoR阀门铸件机加工后出现缺陷的原因，介绍了对缺陷补焊的准备、施焊和检查等工艺过程，总结了补焊的方法和操作经验。     

薄壁零件快速原型成型工艺的研究

对于薄壁零件,其快速原型的成型工艺与一般零件的成型工艺有着很大的不同,本文结合汽车覆盖件快速原型制件的成型,对这类零件的快速原型成型工艺进行研究,提高制件的加工精度和表面质量。     

Flexible Air-Jet Tooling for Vibratory Bowl Feeder Systems

Vibratory bowl feeders (VBFs) are machines that feed various small parts in large volume automatic assembly systems. Their shortcomings, like inflexibility and the propensity to jam, stem from the use of mechanical orienting devices. Air jet based orienting devices can be implemented to overcome these limitations. Applications of passive and active air jet based orienting devices that replace conventional devices for the VBF are discussed. Passive devices, which reject incorrectly oriented parts, are discussed first. Active air jet based orienting devices are introduced to further improve the flexibility of VBFs. Since active devices reorient parts into a desired orientation, the part motion under their influence is analyzed. A number of tests demonstrate the feasibility and advantages of these new orienting devices.     

A comparison of tolerance analysis models for assembly

Mechanical products are usually made by assembling many parts. The dimensional and geometrical variations of each part have to be limited by tolerances so that it can ensure both a standardized production and a certain level of quality defined to satisfy functional requirements. The appropriate allocation of tolerances among the different parts is the fundamental tool to ensure that assemblies work correctly at lower costs. Therefore, to ensure their functionality, assembly designers have to apply tolerance analysis. A model based on either worst case or statistical type analysis may be used. Actually, there are some different models used or proposed by the literature to make the tolerance analysis of an assembly constituted by rigid parts, but none of them is completely and univocally accepted. None of them has done an objective and complete comparison for analyzing the advantages and the weaknesses and furnishing a criterion for the choice and application. This paper briefly introduces three of the main models for tolerance analysis, the Jacobian, the vector loop, and the torsor. These models are briefly described and then compared to show their analogies and differences. Some guidelines are provided as well, with the purpose of developing a novel approach which is aimed at overcoming some of the limitations of these models.     

视觉追踪机器人实时控制系统的设计

介绍了传统追踪机器人的缺陷,并提出视觉追踪机器人.针对视觉存在信息量大、信息处理复杂、系统实时性难以保证等问题,一方面优化机器人各部分之间的相互链接,另一方面在控制系统设计中合理规划和组合硬件功能,发挥各自的优势,避免瓶颈环节,从而能够实现视觉追踪功能并能够较好地解决控制系统的实时性问题.     

基于产品族结构树的定制产品成本估算方法

针对现有的面向大规模定制的产品成本估算方法存在的缺陷和不足,提出了基于产品族结构树的定制产品成本估算方法。该方法是在产品族结构树的基础上将定制产品划分为公共零部件和个性化零部件,个性化零部件进一步分为标准件、外协件、相似件和新零件,针对不同性质的零件采用不同的成本估算方法。因此,定制产品成本估算的关键在于相似件和新零件的成本估算,其中,相似件采用基于实例的推理技术依据相似实例的成本进行估算,新零件采用基于特征的方法计算,最终确定定制产品的总成本。最后以MK2110内圆磨床为例,开发了包括成本估算功能的产品定制设计原型系统,验证了该方法的合理性。     

Analysis of vacuum melting, ultrasonic, and radiographic techniques for gas porosity evaluation in die castings

Parts manufactured using die-casting processes may have significant limitations, mainly due to the tendency for air to be trapped during die-cavity filling. The detection and accurate measurement of porosity due to trapped air are essential issues for improving the quality of manufactured parts. This paper focuses on a comparison of radiographic, ultrasonic inspection, and vacuum melting techniques for analyzing the porosity level due to trapped air in parts manufactured using die-casting processes. To this end, aluminum alloy parts manufactured in a horizontal cold chamber die-casting machine using different injection velocities and mold configurations are analyzed. For the radiographic and ultrasonic techniques, a methodology is established to determine the level of porosity in the part, while, for the vacuum melting technique, a test procedure is established and an expression is obtained to relate the quantity of gas trapped in the part with the pressure increments measured as the part is melted in a vacuum furnace. The advantages and limitations of these techniques to evaluate porosity levels in die-cast parts are discussed in detail. Finally, the possibilities of using these techniques to select operating conditions that reduce the amount of trapped air during the filling stage are analyzed.     

Analysis of the influence of sinter temperature on the joint quality of sinter-joined microcheck valves made of 17-4 PH stainless steel

Whilst powder injection moulding (PIM) of metal or ceramic parts is a favourable technique for producing complex geometries, there are still limitations concerning undercuts, closed cavities or mobile connections. In this paper, a sinter-joining technique of stainless steel parts is presented using the example of a microcheck valve. The valve was produced by an automatic assembly of two powder injection-moulded housing parts and an incorporation of a ceramic ball during the assembly step. The subsequent sintering process allowed fusing single particles and densifying the check valve. To evaluate the quality of the joining step, the contact area was investigated microscopically, and internal pressure tests were performed. The results revealed that a dense contact area can be achieved by using suitable sintering parameters which in turn leads to internal pressure values higher than 700 bar.     

Utilization of 3D printing for an intravital microscopy platform to study the intestinal microcirculation

Intravital microscopy of the intestine is a sophisticated technique that allows qualitative and quantitative in vivo observation of dynamic cellular interactions and blood flow at a high resolution. Physiological conditions of the animal and in particular of the observed organ, such as temperature and moisture are crucial for intravital imaging. Often, the microscopy stage with the animal or the organ of interest imposes limitations on how well the animal can be maintained. In addition, the access for additional oxygen supply or drug administration during the procedure is rather restricted. To address these limitations, we developed a novel intravital microscopy platform, allowing us to have improved access to the animal during the intravital microscopy procedure, as well as improved microenvironmental maintenance. The production process of this prototype platform is based on 3D printing of device parts in a single‐step process. The simplicity of production and the advantages of this versatile and customizable design are shown and discussed in this paper. Our design potentially represents a major step forward in facilitating intestinal intravital imaging using fluorescent microscopy.     

工程零件粗糙表面建模方法研究

随着科技的发展,零件比表面积增加,零件表面几何形貌对设备性能的要求日益显著.由于需要借助有限单元法模拟零件表面上发生的物理、化学现象,因此对零件表面计算机建模的研究具有较强的理论和实际意义.介绍目前粗糙表面的主要建模方法,并指出各种方法的优点及其局限性.     

Laser-arc hybrid welding of wrought to selective laser molten stainless steel

Selective laser melting (SLM) is a successful tool-free powder additive technology. The success of this manufacturing process results from the possibility to create complex shape parts, with intrinsic engineered features and good mechanical properties. Joining SLM steel to similar or dissimilar steel can overcome some limitations of the product design like small dimension, undercut profile, and residual stress concentration. In this way, the range of applications of the SLM process can be broadened. In this paper, the hybrid laser welding of selective laser molten stainless steel was investigated. A high-power fiber laser was coupled to an electric arc and austenitic stainless steel wrought and SLM parts were welded together. The power and speed parameters were investigated. The joints were analyzed in terms of weld bead profile, microstructure, microhardness, and tensile test. The efficiency of the welding process was evaluated through the line energy input versus the weld molten area.     

面向机械零件设计的可选择性拆卸策略研究

机械零件可选择性拆卸规划能够实现从一个装配体上拆除一个或几个零件,这对于产品维修、报废处理和回收利用是非常有用的。尽管完全拆卸规划算法也能得到可行的拆卸序列,但由于完全拆卸规划方法需要将装配体的所有零件都进行拆卸,通过适当的分析和评价也能找到所需的可行拆卸序列,但这是非常困难的,特别当零件数量较多时,通常得不到最优解。本文在建立广义的机械零件CAD模型的基础上,定义了装配体中的拆卸波是装配体中某些零件的一种拓扑关系,可反映零件之间的拆卸顺序。并在此基础上提出了一种基于拆卸波的零件可选择性拆卸规划算法。该算法的计算量小,容易用它来进行高效的搜索,获得最优的零件可选择性拆卸序列。