【作者】 张新玉；

【导师】 张根保；

【作者基本信息】 重庆大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 “零传动”又称直接驱动,其在齿轮加工机床上的应用,完全取消滚齿机传动链的齿轮传动机构,不仅完全消除了传动链的几何误差对加工精度的影响,而且消除了齿轮传动机构生成的热误差对加工精度的影响。但是无法消除电机、轴承等其他因素发热对加工精度的影响。而且由此产生的热误差也在机床所有的误差项中所占的比例大大增加,由原来的40%~70%增加到60%~80%。本文在研究零传动数控滚齿机YK3610结构的基础之上,分析其热特性,重点从理论分析和试验角度研究零传动滚齿机热变形对加工精度的影响,为高效高精度零传动滚齿机热误差补偿提供依据。首先分析了零传动滚齿机的热特性,主要包括热源分析、传热方式和传热计算、发热计算及热变形分析。电机定子和转子发热是零传动滚齿机的主要热源,其中定子发热占电机总发热的三分之二以上。另外,对于高效高精度机床而言,主轴轴承发热也是一个很大的热源,主轴轴承的配置数量和安装方式直接影响其发热量。零传动滚齿机热变形对加工精度的影响是本文研究重点。分析零传动滚齿机由于电机和轴承受热对工件主轴和滚刀主轴可能产生的变形方式,对各种热变形情况进行计算分析,进一步对反映在加工工件上的相关误差进行了数学计算。工件主轴的径向热变形严重影响工件的齿向加工精度,而滚刀主轴的轴向和径向热变形对工件的齿距偏差和齿向偏差都产生很大的影响。从试验的角度主要研究工件主轴和滚刀主轴的热变形。试验发现,受到主轴热结构的影响,工件主轴在径向热变形Y向明显大于X向,对工件加工精度有很大影响,工件主轴轴向热变形很大,但是对加工精度影响很小;而滚刀主轴由于受热结构的影响,径向热变形X向明显大于Z向,对加工精度产生直接影响,而且滚刀主轴的轴向热变形受到尾架的影响,变形比较复杂;利用热变形试验数据计算其对齿轮加工精度的影响。最后,本文主要从结构优化和热误差补偿两方面来研究机床热变形控制技术,以工件主轴为例分析改进电机冷却系统,有利于减小热变形对加工精度的影响;而热误差补偿技术成本低效果明显,文中提出了热误差补偿的建模方法和补偿的实施过程。更多还原

【Abstract】 The technology“direct-drive”has been applied in gear hobbing machine tool, so the structure of gear transmission is removed, which not only reduces the effect of the geometry error on the machining precision, but also avoids the effect of the thermal error from the gear transmission structure on the machining precision. The precision and efficiency are raised greatly. But the effect of the heat on the machining precision, which is from electromotor, bearing and so on, can’t be eliminated on the machine tool. And the rate of thermal error rises greatly in all the errors, which is from 40%~70% to 60%~80%. The heat source, the way of thermal transfer and so on are analyzed based on the structure of Direct-drive gear hobbing machine YK3610. The effect of the thermal deformation on machining precision is focused on theoretically and experimentally based on the machine tool. Thermal error compensation can be performed by it on the high-speed and high-precision machine tool.Firstly, thermal characteristic of direct-drive gear hobbing machine is analyzed in the paper, including thermal source, the way of thermal transfer, calculation of thermal transfer and calculation of heat. The rotor and stator of motor are the main thermal resource, and the 2/3 of the quantity of heat is from the rotor, which is the primary factor leading to thermal deformation on the machine tool. In addition, bearings are another important thermal resource. The layout and the number of the bearings have a direct effect on the quantity of heat.The effect of thermal deformation on the machining precision based on direct-drive hobbing machine is studied on primarily in the paper. The condition of the thermal deformation on workpeice spindle and hob spindle is analyzed by studying on the heat from the motor and bearings. Then error of the workpiece is calculated theoretically, and the error is from the thermal deformation of the spindles. It is known that the radial thermal deformation has an important effect on the gear direction precision from the analysis former. The radial and axial thermal deformations of the hob spindle have a great effect on the gear distance error and the direction error.The best way to testify the effect of machine tool on the machining precision is experiment. The thermal deformation of the workpiece spindle and the hob spindle is studied experimentally. The experiment indicates that the Y-direction thermal deformation of the workpiece spindle is larger than the X-direction one because of the effect of the thermal structure, and the Y-direction thermal deformation has a great effect on the machining precision of the work piece. The axial thermal deformation is very large, but it has a small effect on the machining precision of the work piece. The X-direction thermal deformation of the hob spindle is larger than the Z-direction one because of the effect of the thermal structure, and the axial thermal deformation is very complicated because of the effect of the trail bracket.At last, the control technology of the thermal deformation on the machine tool, including structure optimization and error compensation is studied in the paper. For example, the betterment of the cooling system of the motor can reduce the effect of the thermal deformation on machining precision. The thermal error compensation is in common use, because the cost is very low and the effect is obvious. The way to build mathematics model and the implementary progress are referred in order to compensate the thermal errors in the paper.更多还原