Precision Forming And Process Optimization Of Automobile Hollow Gear Shaft Blank

The automobile gear shaft is one of the important parts of the automobile transmission system.Under the same condition of the cross-sectional area and material,external torque of hollow shaft is larger than that of solid shaft.If the solid gear shaft is replaced by a hollow gear shaft,the self weight of the automobile can be reduced,thereby improving the environmental protection and energy saving of the vehicle,reducing the fuel consumption and reducing the emission.Based on the above purpose,this paper adopts forge2011 software to simulate the hollow gear shaft and orthogonal optimization of rotary forging process parameters,and study the physical verification and isothermal normalizing parameters of rotary forging.Research situation is as follows:(1)According to a type of product structure provided by the partner and principle of volume,the blank and forming characteristics of rotary forging of hollow gear shaft are analyzed,through the UG software to establish a three-dimensional model composed of hollow gear shaft blank,hammer head and core rod,and importing the Forge2011 software for rotary forging related parameters Settings and Multichannel preparation.(2)Mainly analyzes the forging speed,hammer head reduction and so on various parameters influence on the folding defect,effective strain,hammer load,temperature gradient of hollow gear shaft warm rotary forging.Results show: the change of forging speed and hammer radial reduction have a great influence on the folding defects of hollow gear shaft forming;with the increase of axial relative feed;hammer head load has a weakening trend;with the increasing amount of radial pressure hammer,firstly hammer head load increases sharply and then slowly increases;the axial relative feed and radial velocity have significant effect on the temperature gradient of the billet,with the increase of axial relative feed,after the first process of billet maximum temperature,minimum temperature and the initial temperatures at the second process subsequently heighten,with the increase of the radial velocity of the hammer,they first decrease and then increase;the relative amount of axial feeding and radial reduction have a great influence on the spiral spine grain defects of hollow gear shaft forming,with the increase of the relative amount of axial feeding,the surface level changes more and more rapidly,the surface appears even the spiral spine grain,the maximum effective strain value increases first and then decreases,with the increase of radial reduction,the maximum effective strain value increase gradually,spiral spine grain is gradually obvious;with the increase of initial temperature of billet and forging speed,maximum effective strain value decreased after a gradual increasein first,the sharp degree of change is not consistent,distribution of effective strain amplitude is gradually concentrated before radiation,along with the rising of radial velocity of the hammer,maximum effective strain value decreases first and then increases,the degree of deformation is uneven.(3)According to the method of orthogonal experiment analysis to obtain the optimum parameters as follows:the initial temperature of the billet is 830 ?,the relative axial feeding is 0.05 mm,each corner of the billet is 23 °,hammer radial reduction is2 mm,Hammer radial velocity is 7.5mm/s.Physical experiment results as follows:from the microstructure analysis,the rotary forging is used to refine the grains,obtain the fibrous structure and improve the compactness;the variation of microhardness shows the inhomogeneity deformation and improvement of grain density.(4)According to the trial of different isothermal normalizing treatment research,to obtain better parameters for two consecutive different isothermal normalizing process,the process is as follows: the first time isothermal normalizing,heating furnace 930 ? and180 min insulation,5Hz air cooling to 580 ?,constant temperature furnace 580?and150min insulation,air cooling to room temperature;the second time isothermal normalizing,heating furnace 930 ? and 180 min insulation,0Hz air cooling to580 ?,constant temperature furnace 580 ? and 150 min insulation,air cooling to room temperature.Microstructure analysis: horizontal and vertical is uniform distribution of ferrite pearlite organization,grain size and banded structure meet the requirements of manufacturers.