数控机床故障诊断与维修几例

由于现代数控系统的可靠性越来越高 ,数控系统本身的故障越来越低 ,而大部分故障的发生则是非系统本身原因引起的。系统外部的故障主要指由于检测开关、液压元件、气动元件、电气执行元件、机械装置等出现问题而引起的。数控设备的外部故障可以分为软故障和外部硬件损坏引起的硬故障。软故障是指由于操作、调整处理不当引起的 ,这类故障多发生在设备使用前期或设备使用人员调整时期。对于数控系统来说 ,另一个易出故障的地方为伺服单元。由于各轴的运动是靠伺服单元控制伺服电机带动滚珠丝杠来实现的。用旋转编码器作速度反馈 ,用光栅尺作位…     

焊接机器人上旋转编码器功能分析及故障排除

旋转编码器是焊接机器人上一个重要的传感元件 ,用来检测焊接机器人各轴运动角度、位置、速度和加速度。旋转编码器出现故障 ,便会造成焊接机器人停机影响生产 ,并且国外旋转编码器高昂的价格会加大企业的成本。通过近几年的摸索实践 ,我们积累了一些维修经验 ,现将焊接机器人上旋转编码器的功能原理及故障排除作一分析介绍。1　焊接机器人上旋转编码器的功能分析焊接机器人由其控制系统按照一定程序协调各轴运动来完成焊接过程。各轴主要有电动机、电机伺服系统、放大系统和旋转编码器等元件组成。旋转编码器与电动机通过轴杆相连 ,电动机…     

编码器在山钢板坯连铸机中的设计与应用

编码器作为现代自动化控制领域的重要测速和定位装置在冶金企业得到了广泛的应用。本文介绍了电机的转速通过增量式编码器反馈给变频器,构成速度闭环控制系统,满足了工艺控制精度的要求。同时PLC通过对接收到的编码器信号进行处理,计算出需要的位置数据,满足现场设备最基本的定位、速度控制要求。另外对调试及应用过程中出现的涉及编码器故障问题进行深入分析,查找出根本原因,杜绝出现类似的编码器故障而影响设备停机。对编码器精心维护保持了控制系统的稳定性,有利于连铸机的日常维护。     

一起数控系统定位紊乱故障的排除

介绍由于不规范接地引起编码器烧损故障以及随后发生的数控系统定位紊乱故障的排除过程.指出数控系统可能出现"隐形故障",需要根据实际情况逐步从硬件和参数两方面进行判断.     

攀钢西昌1650连铸机铸流跟踪系统的改进

攀钢西昌钢钒有限公司炼钢厂1650连铸机铸流跟踪系统原设计每流26个编码器,通过引锭杆、铸坯在流道内不同位置的编码器进行位置跟踪,实现远程监控设备运行状态,长期运行后由于编码器、机械联轴器的问题,导致铸流跟踪系统出现较大偏差,本次针对1650连铸机铸流跟踪系统进行了优化调整,最终优化成每流9个编码器,将铸流跟踪系统偏差控制在合理范围,满足了生产需求,降低了消耗成本。     

ECL多功能天车渣铲升降限位的改造与实践

本文探讨了云南铝业股份有限公司300kA大型预焙电解槽系列十台法国产ECL多功能天车渣铲升降限位经常发生故障的原因,通过改造实现了限位器的可靠动作,保证了设备的安全运行,并大幅度降低了设备的维修费用和使用成本。     

园盘剪常见故障分析及处理措施

当园盘剪出现故障时,不但会造成切边质量达不到要求,还会导致酸洗段的停车,形成停车斑或过酸洗等带钢质量缺陷。结合生产实践分析了园盘剪的常见故障,找出故障原因,提出了解决办法,可提高园盘剪的作业率,降低设备的事故率。     

在镗床上精车磨损曲轴实例

一般设备经过长时间运转,各部件会出现疲劳,其精度和性能会大大降低,也就是到了需要大修的时间。另外由于设备超负荷运转、操作不规范等也会导致设备出现各种不正常的情况,致使生产能力下降。采用大修方法来恢复设备原性能,不但可继续利用原机器零部件为企业节约资源,而且比制造新设备节省时间,比购买新设备节约成本。     

旧砂气流再生

型砂是影响铸件质量的一个重要因素。型砂性能不佳,会使铸件产生气孔、砂眼、结疤等缺陷。过去,我厂没有旧砂再生设备,不但新砂消耗量大,而且型砂的性能差。既影响铸件质量,又使铸件成本增加;旧废砂长期集存,堆积如山。     

混凝土泵车臂架系统故障诊断实例

在混凝土泵车的施工过程中,臂架系统会出现动作缓慢和臂架油缸掉臂等故障,这些故障会影响工程的施工进度和施工安全。结合泵车臂架系统的结构特点,从泵车的电气和液压系统进行分析,诊断出故障产生的原因,并提出了故障解决方法。熟悉泵车臂架系统的结构和工作原理有利于迅速排除臂架系统的相关故障。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.