Study On Meshing Stiffness And Profile Modification Of Point-line Meshing Gear Used In Coal Machine

The point-line meshing gear transmission is widely used in hoisting,metallurgy,mining and other fields because of the dual characteristics of line contact and point contact.It has high transmission efficiency,strong bearing capacity and long service life.Coal mine machinery due to bad working environment,impact load,limited space and other characteristics,the transmission device performance and volume requirements are strict,point line meshing gear reducer just meet the requirements.When the point-line meshing gear of coal machine is working,the dense dust,strong vibration and large load are easy to make its meshing poor,the tooth surface wear,fatigue fracture and other damage,reduce the service life.In this paper,the point-line meshing gear pair used in coal machine is taken as the object,and the research is carried out from the aspects of tooth surface model construction,meshing stiffness analysis,tooth profile modification method and contact characteristic evaluation,etc.,which lays the foundation for the research of the point-line meshing gear three-dimensional tooth surface modification theory and the method of noise reduction.The main research contents are as follows:(1)Derivation of the point-line meshing gear tooth surface equation:Based on the space meshing theory,the hobbing tool profile equation of the point-line meshing gear was established,and the transformation matrix between the normal surface and the end surface of the hobbing tool and the meshing gear of the point-line was obtained from the position relationship between the hob and the point-line meshing gear,and the tooth surface equation of the point-line meshing gear was derived.Using Matlab software,the discrete point solving program of tooth surface was developed to reconstruct the three-dimensional tooth surface model of point-line meshing gear.(2)The calculation formula of time varying contact line length of point-line meshing gear and the analytical model of mesh stiffness were established.The formula of time varying contact line length of pointline meshing gear was established by using the slice method and the relation of end parameters.The stiffness analysis model of point and line meshing gear was established by calculating the deformation and flexibility of each part under the load of point-line meshing gear with equivalent tooth profile method.Finite element software Abaqus was used to simulate the meshing deformation of point-line meshing gear pairs,and the effectiveness of the meshing stiffness analytical model was proved by comparing the meshing stiffness simulation value with the analytic value of equivalent tooth profile method.(3)A parabolic modification method for driving gear profile of coal-machine point-line meshing gear was proposed.The sensitivity of installation error of point-line meshing gear pair was analyzed with the help of finite element Abaqus,and the variation law of tooth contact under the influence of center distance error,in-plane axis inclination error and non-plane axis inclination error was explored.The contact stress field and deformation field distribution of point-line meshing gear under different load conditions were studied,and the deformation regions of point-line meshing gear under different loads were obtained.On this basis,the parabolic modification method of the driving gear tooth profile was proposed by combining the profile characteristics of the point-line meshing gear,and the variation rule and recommended value of the maximum parabolic modification amount and modification height under a certain working condition were determined by using the single tooth statics model.(4)Research was carried out on the contact characteristics of the tooth profile modified point-line meshing gear.Based on the above modification parameters,the three-dimensional model of the point-line meshing gear driving wheel was reconstructed,and the hexahedral mesh of the four-tooth model was realized by Hypermesh.The influence of the tooth profile modification on the contact characteristics of the pointline meshing gear was analyzed from the aspects of the maximum contact stress,contact line length,amount of deformationand static transmission error,and the feasibility of the tooth profile modification method was verified.