【作者】 郑冬；

【导师】 周惠兴；

【作者基本信息】 中国农业大学 ， 机械制造及其自动化， 2014， 博士

【摘要】 现代船舶广泛采用柴油机作为动力装置,活塞是柴油机的核心部件,它与柴油机气缸的配合紧密程度直接影响到柴油机的性能,提高活塞零件的加工水平能够提高柴油机功率、降低柴油机的燃油消耗。随着柴油机速度和工作负荷的不断提高,船用活塞普遍设计成异型截面形状,目前最常见的活塞型面是中凸变椭圆型面。因为中凸变椭圆活塞形状复杂、加工精度要求高,采用传统加工方法加工效率较低,加工精度一致性差,难以满足生产需求,所以目前广泛采用非圆数控车削方法来加工中凸变椭圆活塞,使用非圆活塞车削可实现活塞的高效率、高精度和柔性化加工,具有显著的经济效益。本文结合“高档数控机床与基础制造装备”科技重大专项：CK9555大功率船用柴油机活塞加工用变椭圆车床,研发了用于船用中凸变椭圆活塞车削加工的衍生式数控系统,主要研究内容如下：1.分析了中凸变椭圆活塞的形状特征和加工原理,重点研究了数控系统实时性要求与机床整体性能指标之间的关系,提出了工控机与嵌入式实时控制器相结合的上下位机控制系统结构,并在此结构的基础上分析了活塞车床数控系统的性能指标。2.对衍生式数控系统的控制机理及特性进行了研究,把传统数控车系统作为系统的一个独立的、具有高度自治性的智能模块,提出了基于数控车系统有限状态机模型的同步控制方案,实现了衍生功能模块和数控车系统的同步。3.基于DSP芯片TMS320F28335开发了衍生控制器软硬件。提出了时间触发分层有限状态机实时嵌入式软件设计模式,建立了衍生控制器软件的分层状态机模型,基于有限状态机开发了软件的驱动程序、子功能模块和同步控制模块。使用这种开发模式在满足系统硬实时性要求的前提下使软件具有高度模块化和柔性化的结构,提高了系统的开发效率和可靠性。4.基于Matlab软件的Simulink和Real-Time Workshop模块的代码自动生成功能,结合基于LabVIEW开发的实验数据接收软件,开发了音圈电机的伺服控制实验系统。解决了在较高的控制频率下实时伺服控制实验的自动编程和实时监测问题,提高了音圈电机控制算法的研究和实验效率。5.设计了基于改进离散重复控制和PI控制的音圈电机的运动控制器,通过使用低通滤波器和稳定滤波器改善了重复控制系统的稳定性,通过加入PI控制器抑制了系统的随机干扰,使音圈电机的跟踪精度达到了项目要求。6.通过系统调试和实际加工实验验证了衍生式数控系统的正确性和可靠性。更多还原

【Abstract】 Diesel engine is widely used in modern ships as power plant. Piston is the key component of the diesel engine, and how closely the piston combines with the cylinder directly affect the diesel engine performance. By improving the machining technology of the piston, the diesel engine power could be improved and the fuel consumption could be decreased. With the velocity and workload of diesel engine continuously increasing, the cross sections of ship piston are always designed as special shape, and non-circular middle-convex and varying oval (NMVO) surface contour is widely adopted as the profile of piston skirt. When traditional processing method is used for the NMVO piston, low efficiency and poor coherence of machining precision will arise because of the complicated shape and the high precision requirement, so non-circular numerical control turning is widely used to cut NMVO piston for high efficiency, high precision, flexibility and high economic benefit. Financially supported by the "Important&Specialized Science and Technology Project of Ministry of Industry and Information Technology of the People’s Republic of China"(2011ZX04002-132), a new derived CNC lathe system for ship piston turning is developed in this paper. The main work is summarized as following.1. By analyzing the shape features and processing principle of NMVO piston, a new control system scheme consisting of industrial computer and embedded real-time controller was proposed based on the research of the relationship between the real-time performance requirement of the NC system and the technical index of machine tool, and the technical index of this type of NC system is derived.2. By employing traditional lathe CNC as an independent intelligent module with high autonomy, a derived CNC lathe system was developed. The synchronization between lathe CNC and derived modules was realized based on the finite state machine model of the lathe CNC.3. The hardware and software of the derived controller were developed based on TMS320F28335DSP. By proposing a time-triggered hierarchical finite state machines (TTHFSM) pattern for embedded real-time software developing, the HFSM model of the derived controller software was built, and the driver program, function modules and synchronization control module were developed based on FSM pattern. The program developed based on this pattern could nicely meet the real-time request of the system, and the developing efficiency and reliability were improved.4. By combing the automatic code generation function of the Simulink and Real-Time Workshop in Matlab with a Lab VIEW based experiment data receiving software, a new servo control experiment system for VCM (Voice Coil Motor) was developed. The automatic programing and real-time monitoring at high control frequency were realized and the efficiency of VCM control algorithm developing and experiment was improved.5. A VCM motion controller was developed using modified discrete-time repetitive control and PI control. By using low-pass filter and stable filter the stability of the repetitive control system was improved, and the PI controller was employed to inhibit random disturbance. The tracking accuracy of the VCM met the project requirement by using this controller. 6. The validity and reliability of the derived CNC lathe were verified by system adjustment and practical processing experiment.更多还原