Study On Thermal Performance Of Meshing Pair Of Constantly No Clearance Precision Ball Transmission

The constantly no clearance precision ball transmission is a new type of small teeth difference planetary transmission, which has advantages of high efficiency, low noise, strong load capacity, miniaturization structure and so on. So it is widely used in precision mechanical area. On the basis of transmission principle, tooth profile theory and force analysis, contact stress, transient temperature rise and bulk temperature of meshing pairs are researched.The transmission working principle, teeth profile of cycloid groove and force characteristics are analyzed. According to Hertz theory, assumed conditions of spatial engagement contact are put forward. Then calculating model of maximum contact stress between two grooves and steel balls are established and the variation of maximum contact stress is analyzed.According to Blok theory, calculating formulas of instantaneous temperature rising of engagement pairs are derived by using flash temperature formulas. Relative sliding velocities and variable frictional coefficients in the formulas are analyzed. By the use of MATLAB programming, the changing curves of transient contact temperature rising of engagement pairs in one motion cycle are drawn. Meantime, the effects on instantaneous contact temperature rising caused by design parameters are studied.Based on Saint-Venant principle of temperature field, single-tooth meshing model of bulk temperature field of engagement pairs are established. According to heat transfer theory, heat balance equations of bulk temperature field and boundary conditions of calculating regions are derived. Furthermore, the variation of heat flux is analyzed through MATLAB programming. By judging the flow state of lubricating oil in the meshing pairs, formulas of convention heat transfer coefficient of each region are derived.The parametric solid model of meshing pair is established by using UG software. Then, the distribution cloud pictures of bulk temperature are gotten by making steady-state thermal finite element analysis with ANSYS Workbench software. The change law of bulk temperature of cycloid groove is studied through curve fitting procedure. Besides, the effects on bulk temperature field caused by design parameters and lubricating oil temperature are researched.