The Research On The Defects Of The Sinking Section Of The Co-forging And The Research On The Adaptability Of The Co-forging Process

In order to improve the coaxiality of barrel bore and surface quality of chamber,the radial forging processes for both chamber and rifling is the best technology.During the processing,there were wrinkles on the inner surface of the barrel.This paper uses the finite element simulation method and the forging test combined with the scanning electron microscope test and the morphological scan test to conduct the following research:Based on the 5.56 mm rifled barrel,a two-dimensional finite element model of radial forging of barrel is established by using the finite element software ABAQUS.The ratio of the circumferential strain to the radial strain of the sinking section during the forging process is investigated detailedly.They are found that the radial strain and the circumferential strain in the sinking section during the forging process were approximately linearly distributed,and the slope of the fitted straight line was approximately the ratio of the radial strain and the circumferential strain?_r/?_?.The strain ratio was determined by forging process parameters.By changing the forging process parameters(such as the inner diameter of the blank,the thickness of the blank,the forging angle of the hammer head,the chunk force and the axial feed rate),the effects of changes in the process parameters on the absolute value of the strain ratio|?_r/?_?|were studied.Refer to the results of ABAQUS finite element simulation,we designed experimental research scheme of strain ratio on forming law of sinking section.Through forging test,combined with scanning electron microscope,further analysis and research of the sinking section and the rifled part were conducted.The results showed that the wrinkles were formed in the sinking zone firstly during the radial forging processing.With the increasing of deformation,the depth of wrinkles became bigger gradually.A 3D topography scanning microscope was used to scan the topography at different positions in the sinking section to obtain two-dimensional topography data,and obtaining the data of the wrinkle depth per stroke in the sinking section.The results show that the wrinkle depth per stroke can be expressed by the ratio of radial strain and circumferential strain?_r/?_?.Combined with he number of the stroke required for whole sinking zone,the wrinkle depth at the final position of the sinking section can be expressed.The prediction of the wrinkle depth helps to prevent the wrinkles from being squeezed into fissure in the forged zone.The circumferential compression ratio?c of the material has a greater relationship with the formation of cracks in the rifling position.The depth of the wrinkles generated at the final part of the sinking zone also has a large effect,and the depth of the wrinkles is proportional to the absolute value of the strain ratio.We can get criterion for fitting cracks by hyperbola.Finite element simulation of 5.56mm,5.8mm and 7.62 caliber tubes based on the existing forging process parameters,analysis of co-forging adaptability of the process,and through the modification of forging parameters,establishment of different caliber body tubes with forging process Illustration.