Study On Meshing Efficiency And Wear Of Plastic Line Gear

Gears are essential components in manufacturing industry.With the development of high quality and green in manufacturing industry,the demand for gear products which have higher efficiency,lower wear rate,and longer service life is increasing.Therefore,research on high performance novel gear mechanism becomes more important.At the same time,with the rise in the fields of mobile communication,automotive electronics,and smart home devices,the demand for plastic gear products is increasing.Therefore,research on plastic gears also becomes more important.Line gear,a novel gear mechanism based on the space curve meshing theory,achieves transmission through the continuous point-contact meshing of a pair of space conjugate curves named driving and driven contact curves.A line gear pair can achieve pure rolling meshing by selecting the parameters of the contact curves.Thus,line gear pair has the advantages of high meshing efficiency and low wear rate under dry friction conditions.A lot of studies on the design theory and manufacturing technology of line gear have been conducted.However,there has been no research on the transmission performance of plastic line gear.Based on the design theory of line gear,the meshing efficiency and wear of plastic line gear under the conditions of dry friction,low rotational speed,and light load were studied in this dissertation.The main work can be summarized as follows:(1)The sliding rates of line gear pair considering assembly misalignment were studied.First,the effects of shaft angle on the sliding rates of line gear pair were studied.Taking parallel line gear pair(PLGP)as an example,the assembly misalignment of line gear pair was defined,and the equations of tooth surfaces and surface normal vectors were deduced.The meshing positions,contact curves,and sliding rates considering assembly misalignment were obtained by tooth contact analysis method.Then the effects of assembly misalignment on the sliding rates of PLGP were studied.(2)The contact pressure and deformation of plastic line gear were studied.First,force analysis for line gear pair was conducted.Based on the point-contact model of line gear pair and the viscoelasticity of plastics,the contact pressure and deformation of the plastic line gear were sovled by influence coefficient method.Then the effects of assembly misalignment on the normal force and maximum contact pressure during the meshing process were studied.(3)Taking polyoxymethelene(POM)PLGP as an example,a calculation method for friction coefficient and meshing efficiency of plastic line gear pair under dry friction conditions was proposed.Ball-on-disk experiment of POM was conducted by using the UMT Tribolab,and the calculation formula for the friction coefficient of POM line gear pair was obtained by fitting the measured friction coefficient data.Relative sliding velocity considering the assembly misalignment,viscoelasticity,and contact deformation was calculated based on the geometric and mechanical models of line gear pair,and the meshing efficiency of POM PLGP was calculated with the calculation formula for the friction coefficient of POM line gear pair.Then the meshing efficiency of POM PLGP was measured using a homemade gear transmission test rig,and the feasibility of the calculation method for friction coefficient and meshing efficiency was validated by comparing the measured and calculated meshing efficiency.(4)Taking POM PLGP as an example,a calculation method for surface wear of plastic line gear pair under dry friction conditions was proposed.Relative sliding distance considering the assembly misalignment,viscoelasticity,and contact deformation was calculated.The tooth surface wear depth and wear zone width were obtained through the Archard wear equation.Wear experiment of POM PLGP was conducted using a homemade gear transmission test rig.The wear zone width was measured by using the TALYSURF surface profiler,and the feasibility of the calculation method for surface wear was validated by comparing the measured and calculated wear zone width.(5)The application of plastic line gear pair was studied.First,the POM line gear specimens were processed by a special CNC milling machine.The comparison of the meshing efficiency and surface wear of the POM parallel line gear pair and POM involute spur gear pair was conducted.A design scheme for the transmission mechanism of the base station antenna remote control unit based on line gear pair was proposed.