Study On The Key Technology Of Precision Forging Compound Forming Of Straight Gear

Spur gear is widely used in all kinds of mechanical equipment.It is one of the most important components in the whole transmission system.With the rapid development of mechanical equipment in China,the demand of gear for the whole mechanical parts market is increasing.At present domestic most gear production is given priority to with machining,some enterprises also produced by precision forging forming way,in the precision forging forming technology,with the continuous development and progress of mould manufacturing technology and mold the development and application of new materials,through precision forging forming of gear,external gear tooth surface is smooth,not only internal metal streamline and in good condition,the quality of the gear is the improved.However,there are still some problems in the process of precision forging,such as low material utilization rate,large forming load,relatively poor precision of gear,and cracks in forging,which greatly increase the manufacturing cost and reduce the forming quality.This paper,taking a certain farm machinery gear transmission system of the steering gear as the research object,from parts of ontology,the analysis of the current problems in the machining process,according to the basic theory of metal plastic forming is put forward a new kind of steering gear of warm and cold composite forming production process,and the finite element numerical simulation from the production process,warm forging process parameters of multi-objective optimization,the composite forming extrusion die structure design and establishment of mathematical model of spur gear precision forging forming composite technology key technology for the comprehensive research system.Against the original machining production leads to low production efficiency,material utilization rate is low,quality defects in gear,steering gear of a complex structure,respectively from the forging materials,forging geometry and dimension precision,mould service life of forging process analysis,combining the theory of metal plastic forming and the rationality of the mould design,determine the compound forming of the steering gear and can be used in practical production process is obtained.The feasibility and rationality of the key forming process in the designed process route are studied and analyzed.Using the finite element numerical simulation software DEFORM-3D design,straight tooth shape of the steering gear and spline forming process numerical simulation research,the results show that the straight gear and spline in the processof forming stress and strain,such as forming force meets the demand of formability,and the forming results is good,combined with the production process in the design of production parameters,proves the rationality of the process feasibility and production parameters.In the process of gear precision forging with 20 CrMnTi alloy steel,the forging produces large residual stress and relatively large forming force,which affects the precision of gear tooth surface and the service life of the die.The influence of different process parameters on residual stress and forming force was analyzed by response surface,and the multi-objective process parameters were optimized to reduce residual stress and forming force.The results show that when the blank temperature is 820?,the deformation rate is 18.8mm/s and the friction coefficient is 0.08,the residual stress and forming force of the gear can be reduced.The size of forming force is related to the selection of forging forming equipment.Although computer simulation can accurately calculate the tonnage,it also has the limitation of computing time and environment.At the same time,the mandrel is used to constrain the forming gear,so it is necessary to design the gap between the mandrel and the blank.If the gap is too large,the forging will be filled in insufficient,and the gap is too small to reduce the forming force.Taking the straight-tooth cylindrical gear as an example,the mathematical model of gear forming force and the calculation model of gear mandril clearance are established by principal stress method in polar coordinates.Based on the mathematical model of forming force,the calculated model of mandrel clearance is close to the simulation test value,which provides the basis for blank size design.The above research shows that the two mathematical calculation models have certain engineering practicability.According to the optimization parameters and production data designed in the previous chapter,combined with the actual production situation,the forming process of the straight tooth part of the steering gear of 20 CrMnTi alloy steel was verified by finite element accurate numerical simulation analysis.The simulation results show that the most complex straight tooth part of the steering gear is formed,the forming force-stroke curve is close to the theoretical derivation,meets the production requirements,and the forming result is good,which provides the theoretical and technical basis for the actual production.