drive directly related to the transmission chain accuracy. Screw selection depends largely on the accuracy of the processing of requests and drag torque requirements. Accuracy is the main requirement of processing may be sliding Screw, but should check the leadscrew wear, such as pitch and pitch error accumulated error and match Nut Gap. Sliding leadscrew general should not be less than six, the nut is too large gap replacement nut. The use of a sliding leadscrew relatively lower prices of ball screw, but it is difficult to meet the high precision machining.
丝杠传动直接关系到传动链精度。丝杠的选用主要取决于加工件的精度要求和拖动扭矩要求。被加工件精度要求不高时可采用滑动丝杠，但应检查原丝杠磨损情况，如螺距误差及螺距累计误差以及相配螺母间隙。一般情况滑动丝杠应不 于6级，螺母间隙过大则更换螺母。采用滑动丝杠相对滚珠丝杠价格较低，但难以满足精度较高的零件加工。
Ball screw friction losses small, high efficiency, the transmission efficiency of more than 90% of high accuracy, long life; starting torque and the torque of close campaigns, starting torque motor can be reduced. So to meet high precision machining requirements.
滚珠丝杠摩擦损失小，效率高，其传动效率可在90%以上；精度高，寿命长；启动力矩和运动时力矩相接近，可以降低电机启动力矩。因此可满足较r精度零件加工要求。
6.4, security
6.4、安全防护
Efficiency must be security as the prerequisite. Machine transformation in the light of the actual situation, we should take corresponding measures must not be ignored. Ball screw is sophisticated components, work to prevent dust particular chip and hard sand into the raceway. Screw in the vertical can also increase overall plate shields. And the extension units at both ends of the sliding contact surface Guide to seal well, absolutely rigid Coarse prevent the entry of foreign matter sliding surface damage Guide.
效率必须以安全为前提。在机床改造中要根据实际情况采取相应的措施，切不可忽视。滚珠丝杠副是精密元件，工作时要严防灰尘特别是切屑及硬砂粒进入滚道。在纵向丝杠上也可加整体t板防护罩。大拖板与滑动导轨接触的两端面要密封好，绝对防止硬质颗粒状的异物进入滑动面损伤导轨。
Seventh, the main steps of CNC machine tools
七、机床数控改造主要步骤
7.1, for the determination of transformation
7.1、改造方案的确定
Through analysis of the feasibility of transforming the future, we can against a Taiwan or a few machines determine the current status of reform programmes, which are generally include:
改造的可行性分析通过以后，就可以针对某台或某几台机床的现况确定改造方案，
