MODBUS RTU在变频驱动液压控制中的应用

文章介绍了Modbus RTU通信协议在变频驱动液压控制系统中的应用,采用基于RS485接口的Modbus RTU通信协议,实现PLC和各变频器之间的串行通讯,通过变频器改变交流电机的转速从而改变液压定量泵的流量。结果表明,该方法实时性好,现场布线简单,提高了系统的抗干扰能力。     

海为PLC与FRENIC-MEGA变频器Modbus通讯浅析

海为PLC内置多种通讯协议,可以方便地使用自由协议、Modbus协议或海为公司的HaiwellBus高速通讯协议与仪表、变送器、触摸屏、变频器等进行通讯,通讯功能十分强大.本文给出了海为PLC与FRENIC - MEGA变频器Modbus RTU通讯实例.     

基于CAN-bus 2.0总线的罐式煅烧炉测温测压系统

采用Modbus RTU现场总线的罐式煅烧炉测温测压系统,虽然较传统的集散控制方式有了一定提升,但是在总线利用率、采集周期、调度及容错机制等方面,受协议本身和RS485固有属性的限制,无法继续优化提升.而应用CAN-bus则可以完全解决上述问题,且从现场施工和后期维护成本来看,优势明显.文中采用的方法,为类似问题的解决...     

基于EtherMAC的新型实时伺服控制网关设计

为解决松下RTEX伺服控制器的开发依赖专用通信芯片MNM1221的问题,提出了一种基于EtherMAC的新型实时伺服控制网关的设计方案。将标准性、通用性更好的EtherMAC工业实时以太网与封闭的松下RTEX协议结合起来,通过研究EtherMAC与RTEX协议的运行机制与特点,设计了一种新型伺服控制网关软硬件方案,完成了两种协议结合的关键时序设计。实现了在不使用MNM1221专用芯片的情况下,将RTEX网络嵌入到EtherMAC总线中,并能对其进行灵活的应用。经Kithara实时运动平台上实验验证,设计的网关产品满足工业控制应用的要求。     

EtherCAT与Modbus协议转换网关的设计及实现

为解决工业应用中不同现场总线协议设备之间不能进行互联互通的问题,首先深入研究了Ether CAT和Modbus两种现场总线协议通信的原理以及运行机制,分析并阐述了基于对象字典映射方法的协议转换网关实现的原理,然后设计了基于"STM32+FPGA"架构的协议网关实现的软硬件方案,并搭建实验平台进行标准协议设备的实验测试,实验结果表明,该网关实现了Ether CAT标准设备与Modbus标准设备通信,从而实现了两种网络协议的转换功能。     

基于Modbus总线的变频器控制方法

本文着重介绍了Modbus总线与汇川变频器的工作原理,并详细研究了通过Modbus总线实现欧姆龙CJ2M可编程控制器控制并读取汇川变频器各项参数的控制方法。     

Devicenet现场总线在压力机中的应用

以欧姆龙Devicenet总线控制器为例,介绍了PLC通过现场总线实现对电子凸轮、装模高度、气垫行程以及主电机变频器的通信控制,并可通过人机界面对其进行实时监控.     

轴控制系统通信技术的研究与实现

为解决工业智能化过程中可编程轴控制器与外设之间的通信技术问题,在分析轴控制器实时可靠通信需求的基础上,对基于Modbus协议的轴控制系统通信技术进行研究。实现了可编程轴控制器与上位PC机之间的可靠通信;轴控制器与被控设备之间的实时可靠通信。最后通过应用验证了该技术方法的有效性。该技术对工业轴控制通信系统的设计具有重要参考价值。     

铝型材氧化着色生产线空压机组变频调速控制系统设计与实现

为了实现风机及大型空压机组的全自动化控制和节能经济运行,提出了一种应用变频器和PROFIBUS-DP现场总线技术改造原电气控制系统的设计方案.系统中PLC通过PROFIBUS-DP现场总线与触摸屏、变频器进行通信,可以控制变频器的启停、给定参考速度、实时读取变频器的主要运行参数,并可以监控其运行状态.实际运行表明,该系...     

三菱变频器在热模锻压力机中的应用

根据工厂实际工程项目案例的应用情况,介绍了三菱变频器在热模锻压力机中的一种应用方式。通过基于Profibus-DP现场总线通讯的控制方式,构建了一套变频器驱动的电机控制系统。根据西门子PLC和变频器之间DP通讯协议的定义,分别对PLC和变频器进行硬件组态,包括外部的硬件连接和DP通讯地址设置、组态PLC内部的通讯地址和变频器内部的通讯参数设置,并通过人机界面可对变频器的参数进行监控和修改,快捷而可靠地实现了PLC和变频器之间的数据传输交换;控制系统实时调整电机的运行状态,改善了电机的工作状况,提高了设备的自动化水平,真正实现了压力机的数字化运行。     

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。