| Gear is the most basic component of mechanical transmission system,and the tooth flank accuracy directly affects the transmission accuracy of the mechanical system.The tooth flank correction is one of the important methods to improve the tooth flank accuracy.The femtosecond laser tooth flank refinement has the advantages of high precision,flexibility and no thermal influence.In this study,the refinement mechanism and technology of the tooth flank are investigated according to the femtosecond laser ablation dynamic-energy heat-transfer model,which mainly includes the following aspects.First,the ablation process of femtosecond laser irradiating gear material20 Cr Mn Ti was investigated and the general law of femtosecond laser removal of gear material was analyzed.Based on the non-Fourier heat-transfer phenomenon and the dual-temperature equation,the femtosecond laser ablation dynamic-energy heattransfer model was developed to investigate the temperature change condition of electrons and lattice.Based on the pulsed laser energy accumulation effect,a femtosecond laser refinement tooth flank three-temperature heat-transfer model was developed to investigate the lattice-to-lattice heat-transfer.Second,based on the finite element software,the femtosecond laser ablation dynamic-energy heat-transfer model and the femtosecond laser refinement threetemperature heat-transfer model were calculated to reveal the temperature fields of different laser energy densities and the temperature variation laws of electrons and lattice at single and multiple pulses when femtosecond laser ablated gear material20 Cr Mn Ti.The laws of laser energy accumulation of laser scan speed and scan spacing on ablation morphology were investigated for femtosecond laser line and the flank processing of gear material 20 Cr Mn Ti.Then,the theoretical coordinate system of the tooth flank was established by the division of the tooth flank measurement points,and the correction thickness of the femtosecond laser tooth flank refinement was determined.The path of femtosecond laser tooth flank refinement was determined by partitioning and layering the tooth flank according to the contour map.The specific components of the femtosecond laser tooth flank refinement system and the specific steps of the femtosecond laser tooth flank refinement were expounded.Finally,the experiment of femtosecond laser point,line and flank corrections was carried out in conjunction with the parameter range of finite element simulation.The morphology of ablation pits,ablation grooves and ablation areas were measured for different laser processing parameters.The effects of laser energy density,pulse number,scan speed and scan spacing on the morphology of ablation pits,ablation grooves and ablation flanks were analyzed,the feasibility of the femtosecond laser tooth flank refinement was verified,and the optimal parameters for the femtosecond laser tooth flank refinement were obtained,thus providing a theoretical basis for the femtosecond laser tooth flank refinement. |
