| Herringbone gear is an important part of mechanical transmission system.It has the advantages of large transmission power,high reliability,high accuracy and strong carrying capacity.It plays an important role in the field of heavy machinery such as aerospace and shipbuilding.In the process of application and research of herringbone gears,many characteristics and conclusions of helical gears have been analogized and used.There are no special technical specifications for Herringbone gears yet.But,the research finds that there are obvious differences between the herringbone gear and the helical gear in some aspects.Exploring the unique difference between herringbone gears and helical gears can provide theoretical guidance for further research and application of herringbone gears.The following research analysis was completed for this purpose.Firstly,the parametric equations of the involute and transition curves of the herringbone profile are constructed.The three-dimensional parametric model of the herringbone gear is established by Pro/E software,and the model is parameterized.By inputting the basic parameters of the herringbone gear,the corresponding involute model of the herringbone gear can be obtained quickly and accurately,which improves the eff-iciency of the accurate modeling of the gear and lays the foundation for the finite element analysis.Secondly,according to the dynamic meshing of herringbone gears,the change rule of gear contact line is analyzed,and the calculation method of gear contact line is determined.The influence of the helix angle on the effective contact width of the herringbone gear is explored.The research shows that the herringbone gear cannot be blindly equivalent to the helical gear for analysis and calculation.On the basis of determining the length of the contact line of the herringbone gear,the change rule of the contact area of the gear is calculated.The analysis shows that the contact area of the herringbone gear changes nonlinearly,which provides a basis for the analysis of the meshing stiffness of the herringbone gear.Then,the stiffness of herringbone gears is compared and analyzed by Weber and finite element method.It is found that the difference between the two methods is about 1.2%.Based on the analysis of Velex method,the improved Velex method is proposed.The meshing stiffness of herringbone gears is compared with that of Weber method.The difference is only 6.8%,which shows the effectiveness of the improved Velex method for analyzing the meshing stiffness.At the same time,the influence of the parameters such as the helix angle,the modification coefficient and the tooth width of the herringbone gear on the meshing stiffness is analyzed.By comparing the herringbone gear and the helical gear model,it is found that the meshing stiffness of the herringbone gear is 2.3 times that of the single-sided helical gear.The herringbone gear cannot be simply regarded as the performance superposition of the two sets of helical gears.Finally,based on the analysis of the relative sliding principle of meshing tooth surface,the relationship between the relative sliding speed of the herringbone gear and the frictional heat is calculated.The finite element method is used to simulate the friction heat generation during the gear meshing process.The change of temperature field of single tooth model is studied.The influence of modification coefficient on temperature field is studied in steady-state thermal analysis.It is found that positive modification is helpful to reduce friction heat produced by gear transmission.The thermal stress of herringbone gear was studied by thermal-structural coupling method,and the effect of temperature on the stress of gear was explored.It was found that the thermal stress analysis of herringbone gear and helical gear was also different. |
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