大型颚式破碎机偏心轴激光熔覆再制造技术研究

为了实现对大型颚式破碎机偏心轴的激光熔覆再制造修复，采用激光熔覆技术在偏心轴材料40CrMnMo试验轴段上制备铁基熔覆层。通过正交试验选择最佳的工艺参数，研究了最佳工艺参数下的熔覆层组织性能，利用金相显微镜、显微硬度计对熔覆层的金相组织、显微硬度进行了研究，最后成功对偏心轴进行了激光熔覆再制造修复，恢复了尺寸公差，并提高了表面使用性能。经激光熔覆再制造后零件在使用性能和产品质量上都能达到甚至超越新品的水平，但成本仅为新品的三分之一，给客户带来较大的经济效益，为水泥行业的再制造发展提供一种新的先进技术，为循环经济的可持续发展提供动力。     

大型颚式破碎机偏心轴激光熔覆再制造技术研究

为了实现对大型颚式破碎机偏心轴的激光熔覆再制造修复,采用激光熔覆技术在偏心轴材料40CrMnMo试验轴段上制备铁基熔覆层。通过正交试验选择最佳的工艺参数,研究了最佳工艺参数下的熔覆层组织性能,利用金相显微镜、显微硬度计对熔覆层的金相组织、显微硬度进行了研究,最后成功对偏心轴进行了激光熔覆再制造修复,恢复了尺寸公差,并提高了表面使用性能。经激光熔覆再制造后零件在使用性能和产品质量上都能达到甚至超越新品的水平,但成本仅为新品的三分之一,给客户带来较大的经济效益,为水泥行业的再制造发展提供一种新的先进技术,为循环经济的可持续发展提供动力。     

激光熔覆技术在表面失效机械件中的应用

阐述了激光熔覆的技术原理和系统的结构,重点介绍了激光熔覆技术在耐磨损和耐腐蚀方面的研究进展,总结了磨损失效和腐蚀失效机械件的修复再制造的具体应用,分析了激光熔覆技术在失效机械件修复再制造应用的可行性和先进性,展望了激光熔覆技术在失效机械件上的应用前景.     

挤压造粒机螺杆元件表面激光熔覆工艺研究

本文采用激光熔覆工艺在38ClMoAl基体上熔覆5～6 mm两种Cr18系列新型熔覆材料，分析熔覆金属的组织形貌，并测定其耐磨性和硬度变化；通过对比修复螺杆原件前后内孔花键尺寸，判定激光熔覆工艺修复过程中的变形量大小。研究结果表明，熔覆金属与基体结合良好，主要是以枝晶状马氏体为主，枝晶间弥散分布着硬质碳化物；在熔覆层与基体之间其形成细小的热影响区，熔池液体沿垂直于界面的最大散热方向快速生长，形成了明显的向上生长的胞状晶、树枝晶。1#熔覆金属硬度平均在50～52 HRC,2#熔覆金属的硬度平均在54～57 HRC之间；通过磨损对比可知，两种熔覆金属磨损失重分别是是45#淬火钢的68%和36%。检测对比螺杆元件修复前后的尺寸，采用激光修复后的零件尺寸变形量平均在0.12 mm以内，符合修复要求。     

煤矿机械应用激光熔覆技术的研究与实践

结合现代采煤机械对耐磨、耐蚀性能的技术要求,对采用激光熔覆技术改善工件表面性能的实践进行了总结,重点介绍了激光熔覆技术在截齿、采煤机高速轴、液压支架及掘进机密封套上的应用,对煤矿机械激光熔覆材料的选择也进行了讨论。     

铜合金表面激光熔覆温度场数值图像模拟分析

对铜合金表面进行激光熔覆镍基合金,能够有效改善铜基件的性能。以镍基合金为熔覆材料,对铜合金基件进行激光熔覆实验;基于有限差分法来构建熔覆过程中温度场数字图像的二维数学模型,对边界条件和基体内部相变潜热做数值化处理;最后对实验实际测量值和模拟计算值进行分析。结果表明,铜合金表面激光熔覆镍基合金的冶金结合良好,证明了提出的温度场计算模型精确度高、稳定可靠。     

激光熔覆焊在离心式压缩机轴头及半联轴器中修复的应用

通过对等离子喷涂和激光熔覆焊修复技术进行性能对比分析，采用激光熔覆焊技术修理的离心式压缩机转子轴头和液压装配式联轴器，经装机运行检验其性能完全满足机组运行要求。     

船舶海水管路激光熔覆涂层研究进展

首先分析了海水管路腐蚀失效原因；其次，从激光熔覆耐蚀金属涂层的性能、熔覆金属涂层的工艺以及复杂工件内部熔覆涂层的现状3个方面进行综述；最后，总结并为海水管路激光熔覆涂层的研究和发展指出了方向。     

大型往复压缩机曲轴裂纹的激光熔覆修复

阐述了激光熔覆技术的原理与特点,介绍了应用激光熔覆技术修复大型往复压缩机曲轴曲柄销表面裂纹的简要过程及该曲轴修复后的运行情况。实践证明,激光熔覆技术具有覆层缺陷率低、组织细密、性能优异、与基体结合牢固及在加工过程中对基体的热影响极小、工件变形小等优点。     

激光熔覆技术在压缩机转子修复上的应用

介绍了离心式氮气压缩机因故障造成的叶轮、形环、高速轴损坏情况.采用激光熔覆技术成功修复叶轮、形环、高速轴并安装,经使用各项性能技术指标正常.     

基于冻结浆料的分层实体制造法加工陶瓷坯体

提出了一种新型陶瓷增材制造方法,浆料由陶瓷粉末、有机粘结剂和去离子水构成,单层生坯的加工过程包括:铺料、冷冻和激光扫描,层层累积成型后,将冻结状态坯体置于冷冻干燥机中干燥,得到陶瓷生坯;分析了激光加工参数和浆料固含量对于激光扫描过程的影响.结果表明:采用激光扫描图形轮廓的方式,避免了激光辐照对材料内部结构的破坏;通过与冷冻干燥技术的结合,充分保留了片层状的孔隙结构;随着激光能量密度的增大,激光扫描线的宽度和激光切割的深度增大;随着浆料固含量的增加,受陶瓷颗粒对激光能量产生散射作用的影响,激光的切割深度减小.     

光敏CTP技术发展历程及应用现状

本文主要对光敏CTP技术研究与应用现状、技术发展带动设备更新进行分析,指出光敏成像是光敏剂吸收光子后跃迁到其光化学活泼状态,继而发生化学反应生产希望的产物的过程。又指出紫激光CTP具有低廉的激光器维护成本、可靠的设备稳定性、优越的出版速度等优势。     

塑料加工最新技术——激光加工

简要介绍了塑料加工技术——激光加工技术的起源、发展过程及应用领域。详细介绍了塑料的激光焊接技术、激光打孔技术、激光标志技术和激光切割技术的应用技术、方法特点和发展趋势。     

Diode Laser Welding of Polyethylene

A high-power diode laser (HPDL) was used to weld high-density polyethylene (HDPE) sheets. Laser-welded joints were fabricated with different values of laser power and scan speed. Hot-tool welding was also employed to fabricate joints to make a comparison between this consolidated technology and HPDL welding. Initially, laser heating tests were carried out to study the laser–material interaction. Furthermore, welding tests were carried out and tensile mechanical tests were performed to characterize joints and sound specimens. A similar material behavior was recognized for all the specimens. While the laser process resulted in lower strength and ductility, in comparison to the tool-welding process, the aesthetics of the laser-welded joints were remarkable. The best values of the process parameters were individuated for the laser welding and were used to fabricate a closed structure having sharp edges. The same geometry cannot be obtained by any other welding technology.     

Direct selective laser sintering of silicon carbide: Realizing the full potential through process parameter optimization

Direct-Selective Laser Sintering (D-SLS) is a promising Additive Manufacturing (AM) technology for Silicon Carbide (SiC). The appropriate values for the process parameters should be employed to achieve considerable success in the D-SLS of SiC. These process parameters include laser power, scanning speed, layer thickness, hatching space, and compaction ratio. A numerical model has been developed to determine the optimal process parameters for the D-SLS of SiC to be used as a guide during the experimental research. SiC samples were successfully printed using the estimated parameters from the numerical model, proving the reliability of the developed numerical model. With varying layer thicknesses of 22, 30, and 40 μm, the scanning speed at various values, including 100, 250, and 500 mm/s, was investigated. It was possible to print SiC samples with a relative density of 82% directly on a metallic base plate using low scanning speeds and layer thicknesses as low as 22 and 30 μm. This result was the first study to print SiC directly on a metallic baseplate. This remarkable finding will enable many applications that previously required metallic and ceramic materials to adhere together during SLS/M-based 3D printing. The process parameters were optimized to achieve a relative density of 87%, resulting in a laser power of 45 W, a scanning speed of 100 mm/s, and a hatching space of 40 μm. The evaluation of mechanical performance should be considered a future study.     

选择性激光烧结聚苯乙烯/玻璃纤维制件的工艺研究

将聚苯乙烯(PS)粉与玻璃纤维(GF)粉通过机械混合制备复合粉料,利用选择性激光烧结技术制备了PS/GF烧结制件,在激光功率25 W、预热温度75℃下研究了扫描速度、单层厚度和扫描间距对PS/GF制件弯曲强度和Z向尺寸的影响,并对工艺参数进行了正交优化。结果表明,在实验取值范围内,随上述3种工艺参数值的增大,制件弯曲强度呈降低趋势,而Z向尺寸相对误差由正值逐渐向负值发展。正交试验结果表明,扫描速度对制件的弯曲强度和尺寸精度影响最大,扫描间距影响次之,单层厚度影响最小;确定了扫描速度1 200 mm/s、单层厚度0.25 mm、扫描间距0.28 mm为最佳工艺参数,此时制件弯曲强度为10.41 MPa,Z向尺寸相对误差为2.35%,基本满足制件的应用要求。     

液压滑升模板工艺在陕西麟北煤业冻结主井的应用

液压滑升模板施工工艺大多应用于地面筒仓等工程,在冻结井筒、双层井壁、高强度混凝土施工中应用很少。陕西麟北煤业通过技术改造,在主井井筒的施工过程中,采用了液压滑升模板工艺,与普通模板施工工艺相比,该工艺具有无接茬缝、工程质量高、节约劳动力、节省材料费用等优点,体现了较好的技术优势,为类似条件工程中的应用提供了经验借鉴。     

聚醚醚酮的激光加工研究进展

综述了激光增材制造、激光扫描透射焊接、激光刻蚀等激光加工技术在聚醚醚酮及其复合材料加工制备领域中的应用及研究进展,并将该技术与传统加工方法进行比较,进一步说明激光加工技术的原理、优点以及现存的一些亟待解决的问题,最后展望了该技术广阔的发展前景。     

橡胶模具激光清洗的工艺研究

激光清洗模具的原理是利用模具基体物质与表面附着的污垢对某一频率的激光能量吸收系数的差别,使激光能量充分被表面附着的污垢所吸收,从而受热膨胀直至气化,所形成的气体被吸收利用而不损伤模具甚至强化模具基体,以达到绿色清洗的目的。本文从橡胶模具表面颗粒受力、激光清洗的机理与主要性能参数及其光路控制,对激光加工技术的应用进行了探讨。     

Statistical evaluation of laser energy density effect on mechanical properties of polyamide parts manufactured by selective laser sintering

Selective laser sintering (SLS) is a rapid manufacturing technology that builds layer‐by‐layer solid object from particulate materials. Nowadays there are materials that are used to produce prototypes and end‐user parts. Powders might be made from metals, ceramics, polymers, and composites. The union or fusion of the particles is made by the energy provided by a heated environment and a laser beam. Parts are built based on data extracted from its CAD design. The process has many variables that directly affect the mechanical properties of the parts. One important and direct processing parameter is laser energy density. This work evaluated the effect of the variation of the energy density in the mechanical properties of a polymeric material by changing laser beam speed and average power. The analyzed variables were stress at 10% of elongation, flexural modulus, and density of the samples built with polyamide 2200 (PA2200‐EOSINT) using a CO₂ laser (10 W). Specimens obtained by combination of different laser powers (2.7, 3.4, and 4.1 W) and laser scan speeds (39.0, 44.5, and 50.0 mm/s) were submitted to flexural tests. Additionally, volumetric density was calculated with mass and physical dimensions of specimens, and micrograph were taken using scanning electron microscope to analyze the changes of the sintering degree. The results indicated that laser power had more influence over density and mechanical properties than scan speed. The microstructures presented good correlation with the statistical results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009