| Small-module spiral bevel gear plays a vital role in the fields of medical equipment,electric tools,robots and machine tools,and has significant demand and broad development prospects.At present,the duplex spread blade method is widely used for small-module spiral bevel gear in China.The wheel and pinion are manufactured by spread blade cutters,which can reduce the times to clamp the gear blank,and improve the cutting efficiency and accuracy,as well as save the cost.However,the lack of systematic research on the tooth design,contact analysis,tooth optimization-machining and rolling test of small-module spiral bevel gear,the development of high-precision and high-strength small-module spiral bevel gear is seriously restricted in China.This work takes the small-module spiral bevel gear manufactured by duplex spread blade method as the research object,and conducts a systematic study from the tooth surface design and meshing characteristics analysis of the gear pair.The main research content and conclusions of this work are as follows(1)The parameters of small-module spiral bevel gear pair manufactured by duplex spread blade method have been derived.Based on the meshing principle of the duplex spread blade method of the small-module spiral bevel gear,the tangential and high modification coefficient have been calculated,the root of the gear has been corrected with the method of double shrinkage,and the blank geometry parameter has been deduced.Based on the tooth cutting principle of the duplex spread blade method of the small-module spiral bevel gear,the parameter of the double-sided milling cutter has been calculated,and the machining setting has been deduced.(2)The meshing model of small-module spiral bevel gear pair manufactured by duplex spread blade method has been developed.Based on the manufacturing process of the duplex spread blade method of the small-module spiral bevel gear,the active and fillet segments equations of the double-sided cutter have been expressed and transformed by the generated coordinate systems according to the gear pair manufacturing process,the meshing equation has been derived,the point sets of the tooth surfaces of pinion and wheel have been generated,and the solid model of gear pair has been established.Based on the mathematical model of the gear pair tooth surfaces,the tooth contact analysis(TCA)model of the duplex spread blade method of the small-module spiral bevel gear has been established,which considers the machining setting changes and misalignments.Based on the solid model of the gear pair,the spiral bevel gear pair loaded tooth contact analysis(LTCA)model has been established.(3)The influences of load,machine-tool settings and misalignment errors on the mesh characteristic of small-module spiral bevel gear have been investigated.The results show that,except for the LTCA transmission error at 1 Nm,the area of contact patter,transmission error,tooth contact stress and root bending stress all increase with the increasing of the load;the sensitivity of the meshing characteristics of this type of gear gradually increase to the change of horizontal,radial distance and velocity ratio.The sensitivity of the meshing characteristics of this type of gear gradually increase to the shaft angle misalignment,wheel axial misalignment and pinion axial misalignment,and the comprehensive misalignment will make the meshing characteristic of spiral bevel gear worse.(4)Based on the manufacturing process of the duplex spread blade method,the small-module spiral bevel gear pair have been generated and rolls on the rolling testing machine,the meshing patter of the gear pair after rolling has been compared with the tooth contact patters simulated by the TCA and LTCA methods,and the accuracy of the calculation parameters and meshing model of the duplex spread blade method of small-module spiral bevel gear pair have been verified. |
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