Contact Resistance Method Apply Research In Lubricating State Testing

The lubrication state transition research is one of the important branch in tribological fields, Stribeck curve is a classic method in it in early stage, and then Gumbel according to previous research results combined with Stribeck curve established more detailed the lubrication state transition figure. The method proposed the film thickness ratio is an important characteristic parameters in judge lubrication condition, this paper through the contact resistance method to calculate the film thickness ratio and then finished lubrication state transition analysis.This paper describes the resistance, capacitance and capacitance oscillation measuring oil film thickness of principle, through the analysis of the advantages and disadvantages of above methods, and connecting with the testing machine structure characteristics, determined the suitable for measuring oil film thickness test methods, it is the contact resistance method. First of all, the paper development a detection system that based on the contact resistance method with LabVIEW software platform, this system including the data acquisition module, man-machine exchange module, data processing module and data storage module, it have acquisition, warning, filtering processing and data conserve four function, achieved the friction, contact the voltage of the real time measurement results. Test results show that the system has a highly detection speed, high accuracy, well stability, etc. Second through different load contact resistance voltage value, get fit this test voltage range; Finally, through the contact voltage, established relationship with temperature, load and the film thickness ratio.Through study cast iron cylinder and plating chromium nitride piston rings by the contact resistance method,the paper conclusion:1. While the load is 10 MPa,20 MPa and voltage in 0.1V<E0<1.3V, contact resistance voltage value Uc follow with the voltage source E0 value increases; When the load is up to 30 MPa,40 MPa, contact voltage value unchanged. So the test voltage E0 in 0.8V～1.5 V range is more ideal. 2. Contact voltage change trends is more obvious than the change trend of the friction. At the same time, both present instead trend, performance in contact voltage to the maximum but the friction to minimum value, that is, the middle trip. Contact voltage value corresponding to the minimum value but the friction value to maximum, that is the stop trip of reciprocating.3. The film thickness ratio in middle trip without changes with load, temperature, the film thickness ratio’value nearby than 0.9, the area in a mixed lubrication area; The film thickness ratio in stop trip slightly decline with load elevate, and occurs inflection point when the temperature of 180℃, the film thickness ratio’value in between 0.5 and 0.7, the area in the boundary lubrication area;...