捏合块数控磨床的关键技术研究

【作者】 姚海滨；

【导师】 王隆太；

【作者基本信息】 扬州大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 捏合块是同向双螺杆挤出机中广泛使用着一种螺杆元件,其外形较复杂,精度要求较高。目前我国的捏合块制造工艺还相对落后,捏合块轮廓曲线加工精度无法保证,大大影响了挤出机的整机性能。因而,对捏合块的磨削成形机理进行研究,解决捏合块数控磨床研制的关键技术问题,研制出先进高效的数控捏合块磨床,无疑将促进我国的双螺杆挤出机制造工艺水平的提高。捏合块磨削时,由于其形状的特殊性,若零件以匀角速度旋转,则捏合块轮廓面各磨削点的线速度、磨削力等都不一样,这将严重影响磨削质量,如产生波纹、烧伤和形状误差等。针对国内现有加工工艺的不足,我们提出了挤出机捏合块等线速磨削的工艺方法。在对捏合块进行结构分析的基础上,以单位时间内等弧长进行磨削,建立捏合块等线速磨削的数学模型,计算砂轮中心的运动轨迹,自动生成NC数控指令,经实际磨削试验,取得了较好的磨削效果。本论文在扬州大学机电研究所帮助支持下,在外圆磨床基础上改造了一台捏合块数控磨床,根据捏合块磨削所需的运动对外圆磨床的床身、磨头和头架进行了改造,设计了砂轮修整装置,满足了捏合块磨床的精度、刚性和结构合理性要求。所改造的捏合块数控磨床控制系统是以PMAC伺服运动控制器为基础,采用“PMAC+PC”的结构形式研制和开发了专用磨床数控系统,将系统开发平台直接构建于PC微机基础之上,实现软硬件功能模块化,各功能模块之间通过标准的接口协调工作,共同完成捏合块磨削所需的数控功能。所研制的系统具有程序译码解释、插补计算、伺服控制、系统管理等控制功能,它不仅具备了一般商用数控系统所要求的通用功能,而且还具备了捏合块磨床所必需的参数输入、砂轮修整轨迹计算、捏合块磨削和砂轮修整程序自动生成等特定功能。同时,系统还为用户设置了今后根据需求增减的模块。本论文通过捏合块磨削工艺试验,获取了实用可行的捏合块磨削参数。并对磨削参数进行了优化,使捏合块磨削具有较高的磨削效率和质量。更多还原

【Abstract】 Kneading blocks are a kind of screw elements wildly used in co-rotating twin screw extruders, with complicated shape and high precision. At present, it’s lag in technology for kneading block manufacturing, or say, the outline precision of kneading block can not be ensured, which influences the whole property of extruders greatly. Therefore, studying the mechanism of grinding process, resolving the key problems of developing NC grinding machine and developing advanced and effective machine will improve our country manufacture technology level of twin screw extruder undoubtedly.If part rotates at a constant angular velocity during grinding process for its special shape, the linear velocity and grinding force of each grinding point on kneading block profile is different, which influences the grinding quality terribly, resulting in wave, burn and shape errors occurrence. In order to make up the defect of present manufacturing technology, we bought forward the new technology of equal linear velocity grinding. Based on kneading blocks’ structure analysis, making the machine grind with equal arc length per unit time, we built up the mathematical model of the equal linear velocity grinding. During the manufacturing process, numerical control instruction can be produced and the trajectory of wheel center can be calculated automatically. Modified by real grinding experiments, the grinding effective is very good.Kneading block NC grinding machines have already been succeeded developing by the mechano-electronic study center in Yangzhou University. According to the movement of kneading block, the bed body, the grind head, the head frame and wheel dressing mechanical structure of kneading block grinding machine can be designed to meet the requirements of precision, stiff and structure rationalization.The control system of kneading block NC grinding machine based on PMAC motion controller uses the“PMAC+PC”structure to study and develop special purpose grinding machine system, building system development platform on PC directly, realizing blocking division of the function of software and hardware, organizing function block coordination work by standard interface and realizing the NC function together. The system that we studied is a control system, which can make the program decade explain, the interpolation algorithm, the servo control and the system administration work at a time. It has not only a common commercial NC system’s general function, but also does the specific function for kneading block grinder, such as parameter input, calculation of wheel dressing trajectory, kneading block grinding and the wheel dressing program performing automatically. Meanwhile the system developers and the lathe users can add or delete function block according to real time requirement.The available and practical parameter of grinding kneading block can be obtained by grinding experiments. So does the optimum ones, which makes a contribution to gain the high grinding efficiency and quality.更多还原