核主泵密封环复杂形面超精密磨削原理与方法研究

发布时间：2018-03-15 20:59

本文选题：核主泵　切入点：密封环　出处：《大连理工大学》2014年博士论文　论文类型：学位论文

【摘要】：核主泵是核电站中驱动高温、高压和有放射性的冷却剂在堆芯和蒸汽发生器之间循环的核心设备,而密封环是保证核主泵安全、稳定、可靠运行的重要零件。核主泵密封环通常由具有良好机械强度、耐磨损、耐高温和耐化学腐蚀等优异性能的氮化硅、氧化铝、碳化硅和碳化钨等高硬度材料制造,要求达到亚微米级的面形精度和纳米级的表面粗糙度,加工难度极大,其核心制造技术只被国外少数几家公司掌握和垄断,因此研究新型的、有实用价值的密封环超精密加工原理和方法对核主泵的国产化具有重要意义。本文针对核主泵高硬度材料密封环高精度复杂形面的加工难题,提出了采用杯形砂轮以线接触方式磨削成形的原理和方法,并利用现有超精密磨床磨削密封环圆锥面对提出的原理和方法进行了实验验证。具体研究进展包括四个方面： (1)提出了采用杯形砂轮以线接触方式磨削密封环曲面的新方法,建立了杯形砂轮线接触式磨削环形曲面的数学模型并研究了其成形原理；通过求解定义域和定义特征点将砂轮圆周旋转投影曲线分为7类,可据此求解生成曲面原理性面形误差,以决定杯形砂轮相对工件空间位置参数的取值,为超精密机床的结构设计提供理论依据。 (2)建立了基于四轴联动机床以杯形砂轮线接触式磨削密封环斜波纹面的数学模型,研究了机床结构参数和运动参数对磨削斜波纹面原理性面形误差的影响规律,提出了6种运动控制策略,并确定了原理性面形误差可控制在10nm以内的运动控制策略。 (3)对碳化钨硬质合金、无压烧结碳化硅和反应烧结碳化硅高硬度材料圆片进行了杯形金刚石砂轮线接触式磨削实验,通过观察磨削表面微观形貌以及测量磨削表面粗糙度和划痕深度,研究了超精密磨削高硬度材料的表面质量,发现选用粒度比2000#更细的金刚石砂轮时,可以获得表面粗糙度Ra小于5nm的超光滑表面。 (4)利用现有的立轴超精密磨床,建立了杯形砂轮线接触磨削密封环圆锥面的数学模型,分析了磨削表面锥度误差和径向轮廓误差与砂轮主轴倾角(俯仰角和侧偏角)的关系,提出利用平面平晶和激光位移传感器高精度调整砂轮主轴倾角的方法,进行了磨削圆锥面的验证实验,磨削后的圆锥面锥度误差为4.88μrad,径向轮廓误差为119.4nm,周向轮廓误差为231.6nm,表面粗糙度Ra在2nm左右,加工精度和表面质量均优于其技术指标要求。本论文的研究成果能够为我国核主泵密封环超精密制造提供拥有自主知识产权的先进加工原理和方法,有望解决核主泵国产化进程中的一项重要难题、打破发达国家的技术控制和封锁、提升我国大尺寸密封件高精度制造的技术水平和国际竞争力。
[Abstract]:The nuclear main pump is the core equipment that drives the circulation of high temperature, high pressure and radioactive coolant between the reactor core and the steam generator in the nuclear power plant, while the seal ring ensures the safety and stability of the nuclear main pump. The nuclear main pump seal ring is usually made of high hardness materials such as silicon nitride, alumina, silicon carbide and tungsten carbide, which have excellent properties such as good mechanical strength, wear resistance, high temperature resistance and chemical corrosion resistance. It is very difficult to process the surface shape precision of submicron scale and the surface roughness of nanometer scale. The core manufacturing technology is only controlled and monopolized by a few foreign companies. The principle and method of ultra-precision machining of sealing ring with practical value are of great significance to the localization of nuclear main pump. In this paper, aiming at the difficult problem of machining high precision complex surface of high hardness material seal ring of nuclear main pump, the principle and method of grinding forming with cup grinding wheel in line contact mode are put forward in this paper. The principle and method of grinding sealing ring conical face are verified by using the existing ultra-precision grinding machine. The specific research progress includes four aspects:. 1) A new method of grinding seal ring surface with cup wheel by linear contact is put forward, and the mathematical model of ring surface grinding with cup wheel is established and its forming principle is studied. By solving the domain of definition and defining characteristic points, the circumferential projection curve of grinding wheel can be divided into 7 categories, which can be used to solve the theoretical surface error of generating surface, and to determine the value of the spatial position parameter of cup wheel relative to the workpiece. It provides a theoretical basis for the structural design of ultra-precision machine tools. In this paper, a mathematical model of grinding seal ring skew corrugated surface with cup-shaped grinding wheel is established based on four-axis linkage machine tool. The influence of machine tool structure parameters and motion parameters on the principle surface error of grinding skew corrugated surface is studied. Six kinds of motion control strategies are proposed, and the motion control strategies in which the principle surface error can be controlled within 10 nm are determined. Experiments on wire contact grinding of tungsten carbide carbide, pressureless sintered silicon carbide and reaction-sintered silicon carbide high hardness material by wire contact grinding with cup diamond wheel were carried out. The surface quality of ultra-precision grinding materials with high hardness was studied by observing the micro-morphology of grinding surface and measuring the roughness and scratch depth of grinding surface. It was found that the diamond grinding wheel with finer grain size than 2000# was selected. The ultra-smooth surface with surface roughness Ra < 5 nm can be obtained. The mathematical model of grinding sealing ring cone surface by wire contact grinding with cup shaped grinding wheel is established by using the existing vertical axis ultra-precision grinding machine. The relationship between grinding surface taper error and radial contour error and grinding wheel spindle inclination angle (pitch angle and side deflection angle) is analyzed. A method of adjusting the spindle inclination of grinding wheel with high precision by using plane flat crystal and laser displacement sensor is put forward, and the verification experiment of grinding conical surface is carried out. After grinding, the taper error of conical surface is 4.88 渭 rad, the radial contour error is 119.4nm, the circumferential profile error is 231.6 nm, the surface roughness Ra is about 2nm, and the machining accuracy and surface quality are better than its technical requirements. The research results of this paper can provide advanced processing principles and methods with independent intellectual property rights for ultra-precision manufacturing of nuclear main pump seal ring in China, which is expected to solve an important problem in the process of localization of nuclear main pump. To break the technology control and blockade of developed countries and to improve the technical level and international competitiveness of high precision manufacturing of large size seals in China.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM623.4

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