【正文】 er, then may control the executive ponent movement the displacement quantity, the speed and the heading. This kind of system does not need the physical location and the velocity feedback which obtains to the input end, therefore called it the open system, this system displacement precision mainly decided in stepbysteps the electrical machinery angular displacement precision, transmission part and so on gear guide screw pitches the precision, therefore the system displacement precision is low. This system structure simple, debugging service convenient, work reliable, cost low, is easy to reequip successfully. The asynchronous motor or the direct current machine drive, diffraction grating survey feedback closed loop numerical control system This system and the open system difference is: Physical location feedback signal which by position detector set and so on the diffraction grating, induction synchromesh obtains, carries on the parison as necessary with the given value, two interpolations enlargements and the transformation, the actuation implementing agency, by the speed which assigns turns towards the elimination deviation the direction movement, until assigns the position and the feedback physical location 南 京 理 工 大 學 課程設計說明 書（英文翻譯） 12 interpolation is equal to the zero. The closed loop enters for the system Enters for the system plex in the structure pared to the splitring, the cost is also high, requests strictly to the environment room temperature. The design and the debugging is all more difficult than the open system. But may obtain pared to the splitring enters for a system higher precision, quicker speed, actuation power bigger characteristic target. May act according to the product specification, decided whether uses this kind of system. The direct current servo electrical machinery drives, encoder feedback semiclosure link numerical control system Half closedloop system examination part installs in among passes in the moving parts, indirectly surveys the executive ponent the position. It only can pensate a system ring circuit interior part of part the error, therefore, its precision pared to closedloop system precision low, but its structure and the debugging all pares the closedloop system to be simple. In makes the angular displacement examination part and the speed examination part and the servo electrical machinery time a whole then does not need to consider the position detector set installs the question. The current production numerical control system pany factory quite are many, overseas famous pany like German SIEMENS Corporation, Japanese FANUC Corporation。 Native corporation like China Mount Everest Corporation, Beijing astronautics engine bed numerical control system group pany, Central China numerical control pany and Shenyang upscale numerical control country engineering research center. 南 京 理 工 大 學 課程設計說明 書（英文翻譯） 13 When choice numerical control system mainly is each kind of precision which the engine bed must achieve after the numerical control transformation, actuates the electrical machinery the power and user39。s request. Fifth in the numerical control transformation the main mechanical part reequips the discussion A new numerical control engine bed, must achieve in the design that, Has the high static dynamic rigidity。 Movement vice between friction coefficient small, the transmission is ceaseless。 The power is big。 Is advantageous for the operation and the service. When engine bed numerical control transformation should meet the above requirements as far as possible. Cannot think the numerical control installment and the ordinary engine bed connects in has met the numerical control engine bed requirements together, but also should carry on the corresponding transformation to the major ponent to enable it to achieve the certain design request, can obtain the anticipated transformation goal. skids guide rail Said to the numerical control lathe that, the guide rail besides should have the conventional lathe guidance precision and the technology capability, but also must have good bears the friction, the attrition characteristic, and the reduction but sends the dead area because of the friction drag. At the same time must have the enough rigidity, by reduces the guide rail to distort to processes the precision the influence, must have the reasonable guide rail protection and the lubrication. gear The mon engine bed gear mainly concentrates in the headstock and the gear box. In order to guarantee the transmission precision, on the 南 京 理 工 大 學 課程設計說明 書（英文翻譯） 14 numerical control engine bed uses the gear precision class is all higher than the ordinary engine bed. Must be able to achieve the ceaseless transmission in the structure, thus transforms time, the engine bed main gear must satisfy the numerical control engine bed the request, by guarantees the engine bed processing precision. skids the guide screw and the ball bearing guide screw The guide screw transmission relates directly to the transmission chain precision. The guide screw selects mainly is decided requests and drives the torque request in the job precision. Is not used by job precision request Gao Shike skids the guide screw, but should inspect the original guide screw attrition situation, like the pitch error and the pitch accumulative error as well as matches the nut gap. The ordinary circumstances skid the guide screw to be supposed not to be lower than 6 levels, the nut gap oversized then replaces the nut. Uses skids the guide screw relative ball bearing guide screw price to be low, but satisfies the precision high ponents processing with difficulty. The ball bearing guide screw rubs loses slightly, the efficiency is high,