| As the key connecting part of the axle neck,wheel pair and bogie,the high mechanical properties and load requirements require strict overall quality of the parts.In order to lighten the weight of the emu,the aluminum aloy axle box body was proposed.The original castings were replaced because of the better mechanical properties.Axle box body belongs to large complex forging,has structure with reinforcement and the stage of locally convex section mutations,so accurately blank preform design is critical to control the quality of forgings and ensure forging forming process effectively.The shape and size of billet were not accurate and the quality was not stable,the forging parts are easy to crack and fold,so forging quality is hard to guarantee.In this thesis,considered the difficulty of large forgings and the characteristics of the aluminum aloy forging,researched and designed the die forging technology,through the numerical simulation technology and optimization method to optimize the process,obtained reasonable and effective aluminium aloy die forging technology of axle box body,the main research contents are as follows:?1?After analyzed the structural characteristics and forging shape of the aluminum aloy axle box parts,we designed the axle box forgings with flash and machining alowances.Combining the quality problems of the free forging blanks forgings,the conclusion showed that the free forging blanks have low production efficiency and the forging quality is unstable.According to the structural characteristics of large aluminum aloy axle box forgings,the forging forming process was analyzed and designed,including the blank forming process?the first and second blanks?and final forging forming process.And elaborated the influence of the blank process design on the final forging process.?2?According to the die forging forming technology of aluminum aloy axle box body,we used the FEM software Deform to do simulation analysis for aluminum alloy axle box body pre-forging,finish-forging forming process.Mainly analyses the stress and strain distribution,flow and temperature field distribution inside the forgings,die wear and stroke-load curve,etc.According to the results from the finite element simulation,the metal flow of the forgings was uniform,the filling was complete and there was no obvious folding phenomenon.It's initially proved that the forging process is possible.?3?With the problems that occurred from the final-forging finite element simulation,such as non-uniform flashing of forgings,excessive flashes at part positions,and wear of the mold compartment.A multi-objective orthogonal test was established,and the maximum stress and mold wear were selected as inspections indicators and establish comprehensive goals.Used Deform to simulate test,according to the optimal result to select the optimal process parameters combination,the shaping angle was 40°,the blank temperature was 470°C,the die temperature was 420°C,the friction factor was 0.3,and the press speed was 5mm·s-1.?4?The actual production verification of the optimal forging process was conducted in a large-scale die forging factory.The results showed that by using this die forging process and the optimum process parameters,aluminum aloy axle box forgings produced achieved a small degree of flash.There were no cracks in the corners and no discernible surface defects.And forging quality conformed to the customer's requirements.In this thesis,the die forging process of large complex forgings was designed,the finite element simulation technology and optimization algorithm were applied to the entire die forging process,which effectively improved the product quality,reduced the production cost,and increased the market competitiveness of the company.Also,it provided theoretical guidance for the die forging process of aluminum complex large forgings. |
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