摘要
重型数控铣车床是实现大型精密零部件加工的必需设备。在数控铣车床中,C轴即为绕主轴轴线(Z轴)的回转轴,在数控加工中心中,主要利用C轴的功能来实现主轴的插补运动,加工复杂的曲线、曲面。C轴的定位精度是判断高精度重型数控机床精度的一项重要指标,其精度直接决定了加工复杂零部件的精度。影响重型数控机床C轴定位精度的因素很多,而齿隙的大小对C轴定位精度的影响是最突出的,所以,为了提高重型数控铣车床的定位精度必须设法减小齿隙的大小;另外对于C轴传动部分,处于工作状态时的受力变形对定位精度的影响也是不能忽略的。
为了消除C轴传动时传动链末端的齿隙,本文提出了一种采用双伺服电机传动,通过双电机的相互配合来消除传动链末端齿隙的方法。基于理论数学模型,建立了双伺服电机驱动的动力学模型,并且进行了动态仿真。仿真结果表明采用主从式运动的双电机能够很好的实现跟随运动;在分析双电机在运动过程中消除齿隙的原理的基础上,通过引入齿隙模型构建了双电机消隙的动力学模型,并行进行了仿真,仿真结果表明齿隙的存在导致系统的上升时间、调整时间变长,系统响应变慢。
针对C轴传动部分工作时的受力状况,采用ANSYS-workbench软件对C轴部件进行了模态分析和静力学分析,为C轴零部件的设计改进提供了参考依据。
最后,设计了双伺服电机消隙验证实验装置,通过PMAC多轴运动控制器控制双伺服电机联合运动,很好的实现了双电机的驱动消隙功能。实验结果表明,双电机驱动消隙方法可以很好的消除传动齿隙,提高C轴的定位精度。
The heavy and high-precision CNC milling lathe is one of the most necessary equipment in machining large precision parts. In CNC milling lathe, C-axis, that is the gyro shaft around the main axis (Z axis), and in CNC Machining Center, we always using C-axis function to achieve Interpolation movement, maching complex curves and surfaces. C-axis positioning accuracy is an important indicator to determine high-precision heavy-duty CNC machine tools, and its directly determines the accuracy of the precision machining complex parts.
There are many factors affect heavy-duty CNC machine’s positioning accuracy, but the size of backlash is the most important. So, in order to improve heavy-duty CNC machine’s positioning accuracy, we must try to reduce the size of backlash. For anther part of the C-axis drive, when they are working, the deformation under the force can not be ignored.
In order to remove the backlash of the C-axis in the end of transmission chain, in this paper, we propose a method that using two-motor transmission, with two-motor’s complement each other removing the backlash of the C-axis in the end of transmission chain. From a theoretical point of view, we established dynamic model of two-motor drive, and established dynamic simulation. The simulation results show that Using master-slave dual motor sports can follow the movement very well. In the analysis of two motors in the movement to eliminate backlash on the basis of the principle of, we introduce backlash and construction of the double-gap dynamic model of electrical consumption, and conduct dynamic Simulation. Simulation results show that the presence of backlash led to the system rise time, adjustment time becomes longer, slower system response.
Against the state of the force when C-axis is working, use the software of ANSYS-Workbench, analyze C-axis parts’model and static. It is very useful for the design of the components of C-axis.
In the end, we design an experimental device that can remove backlash. With the PMAC’s help, we can control two motors’movement. This experimental device can remove backlash. The results show that two-motor drive gap method can eliminate transmission backlash elimination, and can improve the C-axis positioning accuracy.
引文
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