数控机床服役态全行程尺寸关系模型研究

Research on Dimension Relationship Model Under Service Conditions in Whole Stroke of CNC Machine Tool

重力、热等造成机床在装配时的精度发生变化,因此在机床精度设计时应考虑服役态因素的影响。文章提出一种考虑服役态影响的尺寸关系模型用于机床精度设计。首先对基础件进行离散表征,利用尺寸链理论,建立了服役态全行程尺寸关系模型。其次给出了服役态下尺寸关系模型中各环的等效尺寸计算方法。最后以某型号机床Y轴尺寸为例,进行了服役态全行程尺寸关系模型实验验证。结果显示:在全行程范围内,封闭环尺寸实测值与利用服役态尺寸关系模型得到的计算值最大相差2.2μm,封闭环尺寸实测值与几何态封闭环尺寸计算值最大相差3.8μm,服役态尺寸关系模型更接近于实际情况。

The precision of CNC machine tools changes in the assembly process due to gravity and thermal effect. So,the effect of the service state on the precision should be considered during the design of CNC machine tools. This paper presents a dimension relationship model under service conditions,which is used for the precision design of CNC machine tools. Firstly,the geometrical feature of fixed part is discretized as a set of coordinate points. Then a dimension relationship model under service conditions in the whole stroke of operation is constructed based on the dimension chain theory. Secondly,the calculation method of the dimensions in the model is developed. Finally,Y-axis dimension of a CNC machine tool is tested to verify the dimension relationship model under service conditions. The results show that at any position in the whole stroke of operation,the biggest different is 2. 2μm between the tested values and the calculated values; and the biggest different is 3. 8μm between the tested values and the calculated values.