Investigation On The Error And Meshing Performance Of Helical Gear In Automotive

The meshing performance of helical gears is good because of its curvilinear tooth trace.The operational performance and life span of products is mainly decided by the quality of helical gears.As an essential and direct indicator to evaluate the quality of helical gears,the accuracy grade partition is widely adopted in the actual machining process.The process to manufacture the helical gear is a complex process,in which the cutter machines the workpiece.There is a complex link made up of the cutter,machine tool and the workpiece.The clamping error of cutter,geometrical error of machine tool and the clamping error of workpiece have a significant influence on the quality of helical gear.What's more,the quality of helical gears has a significant influence on the meshing performance of gears which will further influence the operational performance and life span of products.Therefore,in order to control the quality of helical gears in machining process and enhance its meshing performance,the error model of helical gear,the evolving law of the error and its meshing performances in meshing process are comprehensively investigated.Based on the theory of multi-body system,machining principle and engagement,the error model of helical gear is firstly established,in which the clamping error of hob,geometrical error of machine tool and the clamping error of workpiece are involved.Then,based on the error model of helical gear,the mathematical models of evaluation programs?the pitch deviation,profile deviation and the helix deviation?are established to evaluate the accuracy of helical gear according to the standard for cylindrical gears.The calculation models of refining evaluation parameters are also established.Finally,the numerical calculation method is applied to reveal the influence of error elements on the error of helical gears.The results indicate that with the increase of error components,the values of deviations increase for most error components,while other error components have little effect on the deviations.The further statistical results indicated that,the influence of error components,such as?_y???,?_y???,?_y?z?,?_y?y?and?_y??₂?,on the single pitch deviation and cumulative pitch deviation is the most significant and the following are?_z???and?_z??₂?.The influence of error components,such as?_z???and?_z??₂?,on the total profile deviation is the most significant and the following are?_x???and?_x??₁?.The influence of error components,such as?_x???and?_x??₁?,on the profile form deviation is the most significant and the following is?_x?y?.The influence of error components,such as?_z???and?_z??₂?,on the profile slope deviation is the most significant and the following is?_x?y?.The influence of error components,such as?_y?y?and S_xzc,on the total helix deviation and helix slope deviation is the most significant and the following is S_xz.The influence of S_yzz on the helix form deviation is the most significant and the following are?_x?y?and S_yzc.Based on the special characteristic of involute,the universal mathematical error models of helical gears are firstly established according to the standard for cylindrical gears,in which different types of profile deviations can be included.Then based on the established error model of helical gears,the three dimensional?3D?models and finite element?FE?models of helical gears are established in the Pro/E and ANSYS software,respectively.Besides,the reasonability of FE models is proved.Finally,the finite element analysis?FEA?method is applied to investigate the influence of different types of profile deviations on the meshing performance of helical gears.The results indicate that the influence of constant value type of profile deviation on the meshing performance of helical gears is minor.The linear increase type and the linear reduction type of profile deviations make the contact regions move forward to the two ends of tooth,which deteriorates the meshing performance of helical gears.When the value of parabolic convex type of profile deviation exceeds a certain threshold,there will be a‘no meshing area',which largely deteriorates the meshing performance of helical gears.However,the parabolic concave type of profile deviation in gear weakens the scrap phenomenon and the waves of contact pressure,contact stress,bending stress,transmission error and torsional stiffiness in meshing process,which enhances the meshing performance of helical gears.The results of this study have a certain theoretical value and practical significance to control the quality of helical gears in machining process and to enhance its meshing performance.