The Research On The Forging Penetration Of The Barrel And The Under-forging Rim And The Establishment Of The Forming Limit Diagram

The machining quality of barrel bore is an important factor to ensure the firing accuracy and the service life of barrel weapon.In order to improve the machining quality of barrel bore,the forging permeability and the possibility of forming micro-cracks of barrel are studied by means of finite element simulation and analytical method.Then the forming limit diagram and the influence of the process parameters on the micro-crack are established.The precision forging of 5.8 mm trapezoidal and tangent rifled barrel are studied.A three-dimensional finite element model of radial forging of barrel is established by using the finite element software ABAQUS.The contact status between bore and mandrel,contact normal stress,and variation of plastic strain of the internal bore during the forging process are analyzed in detail.The criteria of forging penetration are established according to the expressive form of the unpenetrated defect.For trapezoidal rifling,The criteria are that the radial plasticity strain reduction of full forging at the end of the sinking stage to the anode line is greater than one constant value,or the circumferential plasticity strain at each point on the rifling lands should be zero.For tangent rifling,The criteria are that the radial plasticity strain reduction of full forging at the end of the sinking stage to the mid-point of the positive line is greater than one constant value,or the circumferential plasticity strain at each point on the rifling lands should be zero.The criteria are applied to the two types of rifling tubes in the process of pure rifling radial precision forging and rifling integrated radial precision forging,and the forging limit diagram of barrel characterized by the forging ratio and diameter ratio of blank is obtained.The accuracy of the forging permeability criterion and the forging permeability limit diagram were verified through experiment.There are two criteria for judging the formation of cracks during the forging process.one is the ratio of the circumferential to the radial strain,that is,CSR,and the other is the maximum difference of circumferential tension and compressive stress between the hammerhead pressure and the lifting state under the sinking stage,that is,?S_?max.The precision forging of 5.8 mm tangent rifled barrel is studied.A two-dimensional axisymmetric finite element model of radial forging of barrel is established by using the finite element software ABAQUS.And combined with the analytical method,the effects of initial thickness,inner diameter,axial clamping pressure,feed velocity and inlet angle of hammer head on the caving crack were studied from the point of view of strain and stress.