| The variable hyperbolic circular arc tooth trace(VH-CATT)cylindrical gear transmission is a new type of gear transmission with spatial arc tooth trace.The middle section tooth profile is an involute,and other profiles are envelopes of uniformly changing hyperbolic family.Due to the particularity of tooth structure,the variable hyperbolic circular arc tooth trace cylindrical gear transmission obtains the advantages of no axial component force,insensitivity to installation error,reliable lubrication performance and stable meshing characteristics,and shows a good application prospect in high-speed and heavy-duty transmission occasions.Because the gear is a new type of gear,thise gear is mainly processed and manufactured by multi-axis CNC machine tools,and there is no high-efficiency and high-precision special processing machine for the gear,which greatly limits the industrial application of the gear.In this paper,based on the gear processing principle,gear geometry,multi-body kinematics,finite element method and intelligent optimization algorithm,according to the forming principle of the gear,the corresponding processing method,machine tool structure design,processing stability,error characteristic analysis and error compensation strategy are studied.The design method of special machine tool for high efficiency and precision manufacturing of the new gear is proposed,and the error analysis and compensation research of the special machine tool are carried out,which provides a theoretical basis for the optimization design and high-precision machining of the special machine tool for variable hyperbolic circular arc tooth trace cylindrical gear,so as to promote the industrial application of the new gear.This paper mainly carried out the following research:(1)Based on the forming principle of variable hyperbolic circular arc tooth trace cylindrical gear,the machining method of rotary cutter head is proposed.The generating motion relationship between cutting tool and gear blank is studied,and the tooth surface equation of gear is derived.Based on the kinematics of multi-rigid-body system,the topology model of the special machine tool system is established,and the preliminary design scheme of the machine tool structure is proposed.The functional subsystems of the special machine tool are divided,and the key technologies and implementation methods of each subsystem are analyzed,which provides a guide for the design and optimization of the special machine tool.(2)Considering the topological structure and functional characteristics of the subsystem of the machine tool,the geometric model and finite element model of the special machine tool is established,and the static and dynamic characteristics of the special machine tool structure are studied.According to the results of finite element simulation analysis,a structural optimization method for cutter connection stiffness is proposed,and a parameter optimization response surface model for the lower natural frequency of the column is established.The test results show that the optimized machine tool structure is optimized in terms of mass,static stiffness and low-order natural frequency,which verifies the effectiveness of structural optimization and parameter optimization.At the same time,the test results also provides a theoretical basis for avoiding sensitive resonance areas and improving structural strength and static stiffness.(3)The machining stability of special machine tool is studied.Considering the time-varying stiffness,structural clearance and damping coefficient of the cutterhead and spindle,the nonlinear dynamic model of the machining execution system of the special machine tool is established,and the stability variation law of the system is explored.Based on the Melnikov method,the stability threshold range of the system and the possible way into chaos are analyzed.The specific process of the system entering chaotic state is discussed.,and the stability threshold is verified by time history,phase trajectory,amplitude-frequency characteristics and Poincaré cross section.The selection principle of dynamic parameter is proposed,and the machine tool parts are selected according to the principle.The prototype of the special machine tool is built,and the gear processing test is carried out,which verifies the correctness of the machine tool design and the rationality of the selection principle.(4)Based on the gear forming principle,the influence of machine tool error source on tooth surface error is studied.Considering the several geometric error source of the special machine tool,the error description method for the special machine tool is proposed.The conversion relationship between the cutting tool and the gear is analyzed,and the tooth surface equation considering the effect of the machine tool error is derived.Based on the principle of Gleason gear error analysis,the calculation method of tooth surface error is proposed,and the deviation degree and the specific form of gear deviation term of error surface are described.The simulation analysis and experimental verification of the single error source and the comprehensive error source of the machine tool are carried out.The qualitative and quantitative relationship between the machine tool error source and the specific deviation term of the tooth surface is expounded,and the feasibility of the geometric error model of the machine tool is also verified.(5)Based on the improved surrogate model method,the influence of machining parameters on tooth surface error is studied.Based on the meshing characteristics of the gear,the tooth profile error and the tooth direction error of the middle section of the concave and convex tooth surfaces are determined as the optimal response.The full factor test is designed with the cutter head speed,the coolant flow rate and the feed speed as the test factors.Based on the golden section ratio and Chebyshev mapping population optimization,a scene glowworm swarm optimization(SGSO)algorithm is proposed to improve the accuracy and efficiency of Kriging model.The cross factor method is used to analyze the significance of the influence of three key processing parameters on the machining accuracy,and the selection principle of processing parameters is proposed.(6)Based on the differential principle and the error compensation principle,the expression of error compensation for each motion axis in differential form is derived,and the compensation values of linearity and angle are obtained.A compensation strategy based on G code correction method is proposed,and the error compensation test of special machine tool is carried out.The gear data detection is carried out,and the tooth surface error data is measured to verify the effectiveness of the compensation strategy.At the same time,the data of single pitch deviation,cumulative pitch deviation,tooth profile deviation and tooth trace deviation are also obtained,which provides a theoretical basis for the accuracy evaluation of variable hyperbolic circular arc gear. |
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