Study On Wear Modeling And Precision Retaining Ability Of Slide Guide

Precision and precision retaining ability are core indicators of performance of high precision machine tool. Guide pair works as the core part of feed system of machine tool and it decides the machining quality and precision of workpieces. The precision and precision retaining ability of guide pair influence the precision retaining ability of machine tool directly. Slide guide is one kind of most frequently-used guide pair of machine tool. It is a typical sliding friction system, definitely, wear is the primary factor to cause the precision attenuation of the slide guide. Consequently, it is significant to construct the wear model of slide guide and conduct the prediction and design of the precision retaining ability of slide guide in order to improve the precision retaining ability of domestic manufacturing equipment.Many theoretical wear models and corresponding formulae have been constructed, however, there are some limits or large deviations in applying these wear models to predict the wear loss in engineering practice. For slide guide, it is still a challenge work to construct a quantitative wear model based on the wear mechanism of the slide guide in actual working condition to predict wear of the slide guide correctly. Consequently, through analyzing the microscopic and macroscopic wear characteristics of slide guide, an analytical wear model of slide guide was constructed in this paper, furthermore, the modeling analysis and experimental study of the precision retaining ability of slide guide was conducted in this paper. The main research contents and results of this paper are as follows:(1) Three-dimensional topography parameters of surfaces of slide guide samples were obtained by topography meansurement of Taylor Hobson surface coarseness profiling instrument, which were used to statistically reconstruct the rough surfaces of slide guide. Through some equivalent transformation of the constructed asperity model of slide guide surface, the dynamic contact model of slide guide was constructed, which could be used to calculate the number of dynamic contacts of surface asperity during the sliding process of slide guide.(2) A simulation model of dynamic contact of surface asperity was established based on the asperity model of rough surface and the dynamic contacts of surface asperity were simulated. It turned out that the relative error of the calculation and simulation results of the number of dynamic contacts was 2.9%~24.7%. The calculation results fit with the simulation results, the analytical dynamic contact model of surface asperity was validated.(3) A mean fatigue damage equivalent of asperity was proposed for the construction of the fatigue damage model of asperity. The fatigue damage model provides an efficient way to evaluate the micro material removal of asperity. Friction fatigue tests of typical samples of HT200 and 1045 steel were conducted in a reciprocating friction tester to analyze the fatigue damage characteristic of contact surfaces and obtain the friction fatigue exponent which is a critical parameter of wear calculation.(4) Through the integration of the micro wear loss of asperity during the sliding friction of slide guide, the macroscopical wear model and its analytical wear formula of slide guide were constructed.The analytical wear model describes the quantitative relationship between the wear behavior of slide guide and its main factors including working conditions, surface topography, material property and friction property. A lot of pin-on-disc wear tests under different working conditions and lubrication conditions were conducted to analyze the wear behavior of HT200 versus 1045 steel and quenched HT200 versus quenched 1045 steel. The predicted results fit with the experimental results with the relative error of 9%~26%, which validated the reasonability and applicability of the wear model.(5) Based on statistical theory, an analytical model of precision retaining ability of slide guide was constructed by analysis of the wear characteristics and accuracy attenuation of slide guide under working condition. The model describes the quantitative relationship between the precision retaining ability and its influencing factors including working condition parameters, running parameters, material property and wear coefficient.(6) A test bench of precision retaining ability of slide guides was developed, which can be used to simulate the running condition of slide guide and measure the straightness attenuation of slide guide caused by wear during the running process. Bench tests of precision retaining ability with the slide guide samples under different running conditions were conducted. The relative error of calculated results and experimental results were 6%~22%. It indicated that the calculated results fit with the experimental results and the model of precision retaining ability was reasonable. The applications of the model of precision retaining ability of slide guide and the measures to improve the precision retaining life of slide guide were presented in the end of this paper.The research results of this paper can be used to predict the precision retaining life of slide guide and they can also provide references for the design and improvement of the precision retaining ability of slide guide. And these models can also be appropriate for the analysis of precision retaining ability of other precision sliding pair.