Design Of High Speed Spindle With Ceramics Journal Bearing Lubricated By Viscosity Controllable Water-Based Lubricant

The high speed and highly accurate spindle system at the heart of a high speed machine tool directly influences the development and overall performance of that tool. The most common bearings of motorized spindle are the rolling bearing, magnetic bearing and the gas bearing. However, the vibrancy and noise of the rolling bearing, the excessively sophisticated control system of the magnetic bearing and the lower carrying power of the gas bearing restrict their further development. In this paper, a high speed and accuracy spindle system with hybrid ceramic bearing lubricated by new water based fluid is designed based on the method that on current manufacture technical level the match of theoretical rotary accuracy, rigidity and friction power can be optimized to play best performance of spindle with the controllable viscosity lubricant. The main work of this thesis can be summarized as follows:A green and viscosity controllable water based fluid as lubricant of the high speed and highly accurate spindle is compounded. After main constituents of this lubricant established, the ratio of anti-rust additive can be determined with orthogonal test. On the one hand, the viscosity-temperature relationships and other physical properties of water based fluid with different additive concentration are also obtained in the test.A series of friction and wear tests for hot pressed silicon Si3N4 and reaction sintering SiC are carried out in order to select the manufacture material of ceramics journal bearing and verify the matching performance of water-based fluid and engineering ceramics. The results present that under different lubricating condition SiC friction couples always have higher running-in properties and carrying capacity, smoother surface and lower wear rate, moreover SiO2 layer is more obviously formed and the friction coefficient of SiC will be reduced when SiO2 generates continuously. Besides the water based fluid can match ceramics materials well and exhibit good lubricity.According to the special ceramic materials and the porous restrictor, which is applied for its high rigidity and excellent stability with vibration damping under certain conditions, the TEHD numerical calculation program for high speed hybrid bearing is compiled to solve modified Reynolds equation and thermal stress analysis with FORTRAN programe and finite element processor. After the optimization analysis, the viscosity of lubricant, the structure parameters of porous restrictor and fluid cavity of journal bearing can be deduced. Based on the dynamic calculation and stability analysis for lubricant film, when the rotor deviates the static balance position, its movement tendency is convergent, and the bearing can be regard as absolute stability according to relative criterion.With the above results, the design for whole structure of spindle system with hybrid ceramic bearing lubricated by new water based fluid can be finished, and there possesses theoretical thermal stability of bearings distribution form and all-contain structure of ceramics journal bearing. Furthermore through the simulation and optimization analysis, the lateral of spindle end should be connected to the vacuum sucker and the inner surface should be combined with HSK-C and HSK-D tool-holder, meanwhile these pre-tightening forces are also optimized. Finally the design of circulating lubrication system and the electrical design of spindle and lubrication system are finished.