Research On Forging Penetration Efficiency And Stress-strain Of Heavy Long-axis Forgings

The development and application of heavy long-axis forgings is closely linked with large equipment in the filed of industry.The blank which is used for producing large forgings has different degrees of internal defects,such as porosity,hole,etc.These defects concentrate near the central axis and affect the quality of forgings.With the increase of the size and weight of the blank,the defects will be more serious.The existence of these defects affects the operation and service life of large forgings directly.The most effective way to improve and eliminate core defect of large forgings is forging.Using forging to repair core defect of large forgings,which is meaning to produce enough large deformation and high hydrostatic pressure in the defective area,and the two factors are indispensable.In this paper,combining with the production practice,finite element software MSC.SuperForm were used to carry out thermomechanical coupled simulation of shaft forgings stretching process,and the forging core penetration and internal stress-strain distribution of the various stretching process were analyzed.The research results show that the equivalent strain distribution is uneven and different in v-shaped anvil stretching.The forging achieves a good forging penetration efficiency after three pass and the cumulative equivalent strain is about 1.6.The deformation of the outer metal is larger than the core mental of forging in four anvil radial forging.The forging penetration efficiency is not enough on forging core.The equivalent strain is under 0.2 on forging core at the head and the cumulative equivalent strain is about 0.8 on forging core at the middle after four pass.When v-shaped anvil stretching,the stress state on forging core in the process of stretching manifests these features,such as biaxial tension uniaxial compression,biaxial compression uniaxial tension and triaxial compression.Under the given condition,the axial stress on the area of forging core underlie the anvil always exist tensile stress when four anvil radial forging.Whether it is v-shaped anvil stretching or four anvil radial forging,the mean stress on the forging core is negative,which is beneficial to improve and eliminate core defects.In order to improve the penetration effciency of four anvil radial forging,the effects of some parameters such as size and shape of hammer,rotation rate,reduction amount and axial feeding were analyzed,which provides an important and useful reference basis to eliminate core defect in the heavy long-axis forgings.