多控制席有线对讲系统的研制

本文介绍了一种应用单片机开发的有线对讲系统,其特点是用单片机实现多席控制,仅用一只8欧姆喇叭就可收话,发话,而且音量大、声音清晰、扩容方便。因此,该系统特别适合于工业、机关、学校、部队等部门调度指挥。     

新的一类微型计算机 (一)MCS系列单片机技术的开发

进入80年代,单片计算机(Single Chip Computer)技术在国外工业过程控制、武器系统控制、智能仪表、机器人、小型通信设备控制、计算机外围设备控制直至家用电器控制等各种领域中均得到越来越广泛的应用,它所具有的高集成化、高可靠性、高性能/价格比等一系列突出优点使得以8080、6800、Z80为代表的8位微处理器相形见绌。随着VLSI技术迅速发展,单片机系列亦不断更新。在这个领域中,目前美国INTEL公司处于领先地位:它率先推出第一个单片机系列——MCS-48系列,接着是MCS-51系列,最近又公布了MCS-96系列和CHMOS的单片机。本文和它的续篇将介绍MCS系列、特别是MCS-51系列的技术开发与应用方面的特点,同时结合我们近年来开展的研究,探索一些应用方法。     

8098单片机作为火控微处理器的应用能力

从８０９８单片机结构特性、内部资源状况出发,根据火控计算机的一般要求,论述８０９８单片机作为火控微处理器的可能性和应用场合,并提出在应用过程中需注意的一些问题。     

新型单片机实验板设计

本文介绍了一种新型单片机实验板,设计新颖,电路简单,方便实用。在有监控程序的情况下可方便地和PC机进行通信,从而为单片机的开发应用提供了一种新的工具。同时,也给初学单片机或微机接口的人提供了实验装置。     

USB控制器CY7C630/1XXA原理及应用

CY7C630/1XXA系列芯片是具有OTP和RSIC特性的低速USB接口微控制器，适用于低速计算机外调，可作为MCS-51和PIC类单片机扩展USB接口的控制芯片，本文介绍了CY7C630/1XXA的一般性原理，给出了应用电路及相关参数，指出了在单片微机USB接口应用中的优点。     

单片机开发的新成果

一套能与用户已有旧设备兼容以扩展其功能,价值低廉,集开发和应用为一体,适用于大专院校科研、教学,中、小企业工业控制的 MCS—51单片机开发装置,已在我院研制成功,并定型生产,它将推动单片机技术在国内的普及和应用。将 MCS—51开发板插入 TP—801单板机 S—100总线插座后,就构成了新的单片机开发装置。拔出该板后,原单板机将恢复一切功能,做到了一机两用。如果在单板机上再加插上     

基于Windows CE．net的仪器控制和数据处理系统的开发

基于RS232协议的串行通讯在工业和分析测试仪器控制及数据传输中有着广泛的应用.目前,分析测试仪器对于所采集到的数据的处理过程随着分析对象日益复杂而变得复杂,而单片机的运算速度和开发进程已经不能完全满足仪器开发的需求.以基于Windows CE.net嵌入式操作系统的带有串口的PDA(Personal Digital Assistant)为平台,以Embedded Visual C 4.0(SP6)为工具,采用串行通讯、多线程技术,构建了针对系列测试仪器的仪器控制和数据处理系统.并对实现过程中的有关关键技术进行了探讨.该系统的开发成功使得下位机--单片机从复杂的数据处理中解脱出来,而仅完成仪器的数据采集和传输工作.这种方案的实现可以大大缩短仪器的开发周期并极大地提高仪器控制和数据处理的灵活性.     

爆炸焊接边界效应的产生,发展和消除

本文着重分析研究在爆炸焊接过程中,三个不同边界区域边界效应的产生和发展,同时对如何消除国边界效应的影响也进行了研究探讨,从而针对目前爆炸焊接普遍存在的这三类边界效应问题,我们通过优化爆炸焊接工艺参数,采用爆炸切焊法,即融爆炸切割技术与焊接技术于一体,消除了边界效应的影响,使焊接复合率达到１００％。     

等精度频率测量方法

介绍单片机应用系统中的频率测量方法,其特点是在不需要复杂的传统等精度频率测量控制的情况下,利用单片机的自身特性,实现宽范围内实用、简单而且精度较高的等精度频率测量.其测量分辨率可达到1×10-6/s.     

一种“乒乓式”频率合成器的设计

本文从数字锁相式频率合成器的原理出发,给出了一种单片机控制的“乒乓式”快速置频频率合成器的设计思想。     

Effect of fusion welding processes on tensile properties of armor grade,high thickness,non-heat treatable aluminium alloy joints

AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the best suitable process among the fusion welding processes such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) by evaluating the tensile properties of AA5059 aluminium alloy joints. The fracture path was identified by mapping the low hardness distribution profile (LHDP) across the weld cross section under tensile loading. Optical and scanning electron microscopies were used to characterize the microstructural features of the welded joints at various zones. It is evident from the results that GTAW joints showed superior tensile properties compared to GMAW joints and this is primarily owing to the presence of finer grains in the weld metal zone (WMZ) and narrow heat-affected zone (HAZ). The lower heat input associated with the GTAW process effectively reduced the size of the WMZ and HAZ compared to GMAW process. Lower heat input of GTAW process results in faster cooling rate which hinders the grain growth and reduces the evaporation of magnesium in weld metal compared to GMAW joints. The fracture surface of GTAW joint consists of more dimples than GMAW joints which is an indication that the GTAW joint possess improved ductility than GMAW joint.     

变极性等离子弧焊换向过程控制方法研究

通过试验证实了变极性等离子弧焊换向过程中存在电弧电流谐振现象,且不同极性的电流谐振峰值不同,依据电弧理论分析发现换向期间等效电弧电阻是一个时变量。对换向电路建模分析和仿真结果表明,在换向期间系统阻尼比为时变量,调整系统阻尼比是降低电流谐振峰值的有效途径。又根据变结构控制思想提出了新的换向控制方法,并重新设计了换向电路,显著降低了电流谐振峰值,改善了大电流焊接时换向器件的工作状态,为大功率变极性等离子弧焊电源的研制和开发提供了依据。     

Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC) in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel (ASS) consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF) consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding consumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW) and Flux cored arc welding (FCAW) were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.     

Feasibility of surface-coated friction stir welding tools to join AISI 304 grade austenitic stainless steel

An attempt is made to develop the tools that are capable enough to withstand the shear, impact and thermal forces that occur during friction stir welding of stainless steels. The atmospheric plasma spray and plasma transferred arc hardfacing processes are employed to deposit refractory ceramic based composite coatings on the Inconel 738 alloy. Five different combinations of self-fluxing alloy powder and 60% ceramic reinforcement particulate mixtures are used for coating. The best friction stir welding tool selected based on tool wear analysis is used to fabricate the austenitic stainless steel joints.     

焊接过程对焊接残余应力及残余变形的影响

采用热弹塑性有限元法 ,对直通焊和多人同时分段焊两种焊接过程的平板对接焊时焊接应力变形和圆柱壳板环缝的焊接变形进行比较 ,认为多人同时分段焊较直通焊无论在降低焊接残余应力还是焊接残余变形都具有非常显著的效果     

直流TIG焊接电弧的数值分析

以直流钨极氢弧焊电弧为研究对象,考虑阴极几何形状,建立了轴对称电弧数值计算模型,在电流密度计算中包括了阴极区和弧柱区。采用ＳＩＭＰＬＥ算法求解磁流体动力学方程组。所得电弧弧柱温度分布与实验结果相吻合;电弧速度分布、电磁力分布、电流密度分布、压力分布等电弧参量的计算结果能较全面地反映电弧内部的作用机制。     

无电焊接热循环测试研究

利用热电偶测试了无电焊接过程中同一厚度钢板不同位置、不同厚度钢板同一位置处的焊接热循环曲线,探讨了无电焊接热循环规律及焊接母材厚度对无电焊接热循环的影响。研究表明：无电焊接时,焊件上不同位置点的热循环曲线与电弧焊基本相似。但相较而言,无电焊接在加热阶段的升温速度与冷却阶段的降温速度均显著小于电弧焊。无电焊接过程中,焊件上离焊缝中心线越近,其升温速度越大,峰值温度越高,冷却速度也越大,这一变化规律与电弧焊时完全一致。无电焊接时,焊接热量沿横向的传热速度远大于其沿纵向的传热速度,这使得焊件厚度对无电焊接的影响较为显著,也是焊件厚度增加将导致焊接难度显著增大的根本原因。     

Influence of magnetically constricted arc traverse speed (MCATS) on tensile properties and microstructural characteristics of welded Inconel 718 alloy sheets

The magnetically constricted arc technique was implemented to mitigate the heat input related metal-lurgical problems in Gas Tungsten Arc Welding (GTAW) of Inconel 718 alloy particularly Nb segregation and subsequent laves phase evolution in fusion zone. This paper reports the direct effect of magnetically constricted arc traverse speed (MCATS) on bead profile, tensile properties and microstructural evolution of Inconel 718 alloy sheets joined by Gas Tungsten Constricted Arc Welding (GTCAW) process. The mechanism amenable for the microstructural modification and corresponding influence on the tensile properties of joints is investigated both in qualitative and quantitative manner related to the mechanics of arc constriction and pulsing. It is correlated to the solidification conditions during welding. The relationship between MCATS and Arc Constriction Current (ACC) was derived. Its interaction effect on the magnetic arc constriction and joint performance was analysed. Results showed that the joints fabricated using CATS of 70 mm/min exhibited superior tensile properties (98.39% of base metal strength with 31.50% elongation). It is attributed to the grain refinement in fusion zone microstructure leading to the evolution of finer, discrete laves phase in interdendritic areas.     

制备工艺对弧焊成形件性能影响研究进展

阐述了弧焊工艺参数、搭接量、层间冷却时间、焊接路径规划以及激光-弧焊复合焊接工艺对成形件组织性能(残余应力、温度场、组织、硬度、抗拉强度)影响的研究现状,总结了尺寸与性能控制一体化快速制造、尺寸控制和表面改性复合快速制造、基于机械加工特征的性能控制等研究新进展,最后指出未来性能控制研究应在性能控制建模、几何尺寸与表面性能控制的顶层设计、弧焊快速制造与纳米表面工程的复合运用等方面加以重视。     

自动化电弧喷涂路径偏移间距的优化模型

基于电弧喷涂沉积丘的轮廓呈高斯分布的假设,并结合实验结果,建立了电弧喷涂沉积丘轮廓的数学模型,由此推导出了自动化喷涂过程中平行路径偏移间距这一重要参量的优化模型。该模型为合理规划自动化喷涂的路径提供了依据。