求翻译：实际的物理量，除了开关量、模拟量，还有数字量。如机床部件的位移，常以数字量表示。 数字量的控制，有效的办法是NC，即数字控制技术。这是50年代诞生于美国的基于计算机的控制技术。当今已很普及，并也很完善。目前，先进国家的金属切削机床，数控化的比率已超过40％～80％，有的甚至更高是什么意思？

The actual physical quantities, in addition to the switch, analog, as well as digital. Such as the displacement of the machine components, often digital. Digital control, effective way to nc, the digital control technology. This is the 1950s, was born in the United States, computer-based control tec

Actual physical volume switch, in addition, analog, there are digital. If parts of the machine, the shift to digital is often expressed. The Digital volume control, and effective way of NC is that the digital control technology. This is a 50 s was born in the United States for the computer-based con

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Actual physical quantities, in addition to switching, analog, and digital. Such as the displacement of machine tool parts, often expressed as a number. Digital volume control, effectively through NC, digital control technology. This is 50 was born in the United States based on control technology of

正在翻译，请等待...