【作者】 李芳；

【导师】 曾良才；

【作者基本信息】 武汉科技大学 ， 机械电子工程， 2005， 硕士

【摘要】 目前,步进梁式加热炉被广泛应用于板材、棒材或线材的热轧生产中,对冷态或热态钢坯进行炉内步进式运送并加热。由于步进炉液压系统作程序循环运动,具有步进周期短、运动速度较高、惯性负载大、大超越负载、多缸同步、连续工作、可靠性要求高等特点,再考虑到步进炉的工艺要求,因而要求设计步进梁加热炉的速度控制系统。 结合武钢热轧厂四号步进梁式加热炉液系统在实际生产中暴露的问题,本文分析了改进液压系统的设计思想及技术措施,确定实际可用的改进方案,对主泵、补油系统、阀站进行升级改进,对系统回路重新设计,以适应现代化的生产节奏,提高生产产量和质量。 本文针对步进梁式加热炉的速度特点,参考国内外已投入使用的步进梁速度控制方式,在分析比较各种方式的优缺点的基础上,结合实际生产情况及工作要求,确定了适合本系统的速度控制方案:泵控缸式容积调速回路。该系统采用先进的电液比例控制技术,保证步进梁按给定的速度曲线运行。避免系统中由于大的惯性力而导致的步进梁前冲等事故发生。在步进梁速度电液比例控制系统中,比例变量泵是关键组成部分。依靠电控系统给出相应控制信号,经比例放大器功率放大,驱动比例方向阀,控制液压泵变量活塞运动到相应位置,液压泵排出所需流量,供系统工作。同时主泵斜盘倾角由位移传感器进行测量,转换为电信号,送入比例放大器作为闭环控制的反馈信号,流量控制精度高。这种速度控制系统中,充分利用了电液比例控制技术的优点,以高性能的电液比例变量泵取代了原四级压力阀块控制的轴向柱塞变量泵,将控制方式由机液伺服控制改为电控方式,简化了液压系统及流量控制系统,减少了故障点,实现了系统的完全标准化,大大提高了系统的控制性能和生产效率,提高了经济效益和社会效益。 本文从理论上分析了步进梁加热炉速度控制系统的基本特性,并通过力学分析比较精确的建立了步进梁加热炉速度控制系统的数学模型,分析了泵控容积调速系统的动态性能和抗负载干扰特性,并进行了仿真。为电液比例速度控制系统的进一步研究提供了理论基础。除此之外,还通过实验与现场安装调试,证实了泵控式容积调速回路完全能满足步进梁实际生产所需要的工艺过程曲线和技术指标,改进后的液压控制系统是可靠的。 另外,针对改进后的液压控制系统投入生产,试运行一段时间后出现的实际情况,文章分析罗列了步进梁工作过程中常见的故障及相对应的处理方法。更多还原

【Abstract】 Now, walking-beam-type reheating furnace is widely used in hot reduction of board, bars and wire stock. It transports hot or cold billet steel step by step in furnace and heat it. Because the hydraulic system of walking furnace moves in program loop and the walking furnace have the characteristics as follows: low step walking periodicity, high velocity, heavy overpass loading, synchronizing multi-cylinder, continuously work, high reliability. We consider of the process requirements of walking furnace, therefore, it needs to design the velocity control system of walking beam type reheating furnace.According to the naked problems in practicable production process of the No.4 walking-beam-type reheating furnace hydraulic system in hot rolling plant, WuHan Iron & Steel(Group) Corp. , the paper analyzes the designing idea and technical measures of rebuilding hydraulic system, makes certain of reliable reform scheme in reality. It upgrades main pump, slippage system, valve station, redesign system circuit to adapt to modern production, increases output and quality.Referring to walking-beam-type reheating furnace’s velocity feature, consulting the velocity control modes which have been put into production in home and overseas, combining the practical production condition and work requirements, on the base of analyzing and comparing all kinds of control modes’ merits and faults, the paper makes certain of the velocity control version which adapts to the system. It is capacity speed governing circuit of pump controlling cylinder. In order to ensure walking beam run in preset rate curve, to avoid happening some accidents in system, for example, the big inertia will result in the ahead impacting of walking beam, the system uses advanced electro-hydraulic control technology. In the walking beam’s velocity electro-hydraulic control system, proportional variable pump is the key components. It depends on the control signal which given by electricity control system to drive proportional directional valve and control the variable pump’s variable piston moved to relevant position after power amplification by proportional amplifier. The main pump discharges flow which needed to operate the whole system. At the same time, the pump’s sloping cam plate angle is measured and translated into electronic signal of closed-loop control. The flow control accuracy is high. In this velocity control system, it makes full use of the merits of electro-hydraulic proportional control, replaces axial plunger variable pump controlled by four-grade-pressure valve block with high performance electro-hydraulic proportional variable pump. The control method changes from mechanical-hydraulic servo controlling to electricity control. It simplifies hydraulic system and flow control system, reduces fault, realizes wholly standardization of system, increases the control performance and production efficiency highly of system, raises economic benefits andsocial benefits.The paper analyzes the fundamental characteristics of walking beam reheating furnace’s velocity control system in theory, and exactly builds the mathematical model of walking-beam-type reheating furnace’s velocity control system by mechanics analysis. It analyzes capacity speed governing system’s dynamic characteristic and anti-interference performance in load. It also simulinks the system. It provides theoretical basis for further research on electro-hydraulic proportional velocity control system. Moreover, it proves capacity speed governing circuit perfectly satisfied walking beam’s processing curve and qualification which needed in practical production by doing experiments and field installation and debugging. The hydraulic control system which has reformed is reliable.In addition, referring to the reformed hydraulic control system put into production for a time, and some problems occurred, the paper represents the common fault in walking beam’s working times and corresponding processing methods.更多还原