A Study On The Relationship Between Car Surface Shaft Waviness And Vibration And Oil Film Thickness

The crankshaft is one of the core components of the engine,and the quality of its surface processing has an important impact on the life and stability of the engine.Waviness is the main standard parameter for evaluating crankshaft quality.Its main characteristic parameters have a certain influence on the vibration generated during crankshaft operation and the performance of the lubricating oil film at the crankshaft journal.Therefore,the relationship of the crankshaft journal waviness and vibration,the characteristics of the lubricating is necessary to improve the performance of the engine and the quality of the crankshaft.In this paper,the research work is carried out on the basis of waviness measurement and analysis of characteristic parameters,with the aim of determining the main concentrated frequency stage of vibration energy,the coherence of waviness excitation and vibration in frequency order and the influence of waviness on the characteristics of lubricating film.The main research contents of this article are as follows:1.Measurement of waviness and analysis of characteristic parameters.The research mainly carried out the analysis of the main evaluation parameters and characteristic parameters of the waviness.For the application object of this subject-the H15 TC type crankshaft,the surface profile measuring instrument Aclcole1200 SH was used to measure the waviness.Perform the characteristic parameter value statistics,time domain,Fourier change and two-dimensional Fourier change analysis on the extracted raw data of the crankshaft journal waviness,explore the distribution rule of the waviness of different sections of the crankshaft journal,and determine the evaluation of the entire crankshaft ripple measured section of the journal for the quality standard.2.Design and construction of the experimental platform.Based on the simulation conditions of the crankshaft driven by the machine tool,a special experimental platform is designed and built.According to the collected signals and parts assembly needs,design and process adjustable height base,specially processed upper and lower bearing cover,standard shaft and other parts.Complete the selection of various sensors,the construction of experimental platforms and the collection of various signal data.3.Research on the relationship between vibration and waviness.Determine the excitation frequency of the waviness according to the operation of the crankshaft;do a spectrum analysis of the vibration signal generated during the operation of the crankshaft to explore the main frequency and the corresponding amplitude of the crankshaft generated by different waviness;through the power spectrum analysis,explore the waviness of main concentrated frequency stage for generating vibration energy;according to the analysis of waviness excitation and vibration coherence,determine the correlation between the two in frequency order.4.Research on the relationship between waviness and oil film thickness.Based on the measurement and feature analysis of waviness,the peak and wave number of waviness are taken as the main characteristic parameters,and the lubricating oil film on the journal is three-dimensionally modeled in consideration of the waviness.Based on fluent software simulation,the effect of wave number and wave peak of waviness on lubricating film pressure,bearing capacity and oil film stiffness was investigated.Determine the measurement method of the oil film thickness at the journal and the minimum oil film thickness when the crankshaft is running,and complete the experiment.