Numerically Control of Servo-Spindle for Machine Tools by Two-phase Type PLL Method

近年来，机床已迅速向数控机床转变，然而，制造数控齿轮切削或磨床一直是一件困难的事情。例如，与全机械滚齿机相比，数控滚齿机不适合制作高精度齿轮。为了克服这一困难，该项目的首席研究员T. Emura试图利用通过对wauding机器人的研究获得的直接驱动技术，制造出适合齿轮制造机器的高精度高速伺服主轴。将T. Emura提出的两相锁相环（PLL）用于控制伺服主轴，以获得高精度、高刚度的旋转运动。本文的研究成果总结如下。我们制造的伺服主轴由内置电机、磁秤和高速旋转所需的动态平衡机构组成（最大转速为12000转）。为了提高系统对周期性扰动的自适应能力，采用了重复控制方法。此外，数控磨齿机通常需要啮合机构来检查和校正刀具与工件之间的相对位移。我们提出了一种新的基于图像处理的网格划分方法，并证明了它的有效性。在采用两相锁相环控制的伺服主轴的数控磨齿机上进行了实验，结果表明，可以快速得到累积误差小于10”的高精度齿轮。

Recently, Machine tools have been rapidly changing to NC machines, however, it has been difficult to make NC gear cutting or grinding machines. For example, NC hobbing machines were not suitable for making high precision gears as compared with full-mechanical ones. To overcome the difficulty, T. Emura, the head investigator of this project, tried to make a high precision and high speed servo-spindle suitable for gear manufacturing machines using the direct-drive techniques which were obtained through the investigation about waudng robots. The two-phase type PLL(phase-locked loop), proposed by T. Emura, was applied to controlling the servo-spindle in order to obtain high precision and high stiffness rotational motion.The summary of this research results-are as follows. we made the servo-spindle which was composed of a build-in motor, a magnetic scale and a dynamic balancing mechanism necessary for high speed rotation(maximum 12, 000 rpm). In order to improve the adaptivity to the periodic disturbance, the repetitive control method were used. In addition, a meshing mechanism is usually necessary for NC gear grinding machines to check and correct the relative displacement between the tool and the work. We proposed a new meshing method using image processing and proved that it is very useful.As a result of the experiments using the NC gear grinding machine using the servo-spindle controlled with the two-phase type PLL, it was proved that we can very quickly get high precision gears whose cumulative error is less than 10".