Driving unit includes actuating device and electric machinery two parts, basically depend on the choice of actuating device to the choose and buy of driving unit, because electric machinery is general component, function difference the manufacturer with different consist in and model. Drive electric machinery basically can divide for: Reaction type situation enters drive electric machinery, Composite (also call permanent magnetism reaction type) the pace enters drive electric machinery and servo drive electric machinery 3 kinds big. Reaction type situation does not have winding into the rotor of drive electric machinery, by quadrature of the stress that be turned over by the stator winding generation of excitation implementation pace is entered move. Composite pace uses permanent magnet steel into the rotor of electric machinery, by excitation and the electromagnetism that permanent magnetism produces pitching moment realizes a pace to enter move. The pace gets the control of pulse into electric machinery, the direction of rotation of the ordinal changeable electric machinery through changing electrify, the rotate speed coming back of changeable electric machinery spends the frequency that changes pulse. The pace has certain step pitch precision into electric machinery, did not accumulate an error. But the efficiency that the pace enters electric machinery is low, pull the capacity that uses load not quite, pulse equivalent cannot too big, timing scope is not big. At present the pace can be divided into electric machinery for two-phase, three-phase, 5 equal a few kinds, commonly used is 5 photographs pace enters electric machinery. In very long in the past period of time, the pace takes very big market into electric machinery, but replacing for place of servo electric machinery stage by stage at present. At present commonly used servo electric machinery is communication servo electric machinery, in the axis of electric machinery end installs glazed report coder, through detecting frequency conversion of rotor angle in order to is controlled. Arrive from lowermost rotate speed top rotate speed, slippery movement of Dou Nengping of servo electric machinery, torsion wave motion is small. Servo electric machinery has longer overload capacity, have lesser moment of inertia and big locked-rotor torsion. Servo electric machinery has the very small frequency that start, very can fast quicken rated rotate speed from lowermost rotate speed. Use communication servo electric machinery to regard drive as parts of an apparatus, can form high accuracy with dc servo electric machinery, high-powered half closed circuit or closed-loop control system. Because communication is to not have inside servo electric machinery,brush a structure, need to maintain scarcely, volume is relatively minor, be helpful for rotate speed and power rise. Had replaced dc servo electric machinery inside very big range at present. Use high speed microprocessor and processor of special number signal (DSP) after complete digitlization communicates servo to appear, original hardware servo control turns into software servo control, the advanced algorithm in theory of a few contemporary control gets coming true, improved the performance of servo greatly then, because this servo is unit can bigger raise treatment efficiency and treatment precision, but the price of servo driving unit is higher also. Rise stage by stage as what servo controls a technology, at present servo driving unit is becoming the main force of driving unit stage by stage, the price of servo driving unit also has two kinds in driver of step down servo. One kind uses pulse to control fashion, this kind of driver and electric machinery closed circuit, but do not feedback numerical control system, this kind of driver is in go up somehow can call control of servo of open loop pilot. Another kind uses voltage to control fashion, the on any account that carries voltage undertakes the rotate speed of electric machinery is controlled, the feedback signal of electric machinery undertakes to numerical control system through driver feedback the position is controlled. When choosing driving unit, the price that also should consider driving unit is in the scale in machine tool of whole platform numerical control. The general choice pace with inferior value of machine tool of whole platform numerical control takes driving unit, and the machine tool with higher price chooses servo driving unit. But choose driving unit while, also want those who consider driving unit and numerical control system to match a question, the choice must choose the servo driving unit of closed circuit when closed-loop control system. Communication servo is in a lot of performance sides excel pace enters electric machinery. But in a few requirements not tall circumstance also enters electric machinery to make executive motor via commonly used pace. So, the design that controlling a system wants to consider integratedly to control the element of the many sided such as requirement, cost in the process, choose proper control electric machinery. CNC MillingCNC Machining