Study On Forming Force And Workpiece Features Of Rack Cold Roll-beating

Today,advanced near net shape technique has become the frontier research field of parts manufacturing technology.Green,energy saving,precision and high efficiency machining technology is one of the key research and development directions in the manufacturing field.It is an important research topic to explore new methods of lightweight,rapid and precise plastic processing.As a new near net shape technique,rack cold roll-beating technique roll and beat intermittently for the roughcast point by point,using a specific profile,high-speed rotation of the rolling wheel,which the characteristic of metal plastic forming is used.And then it forces mental to flow and form component profile.By means of the relative motion relationship between the rolling wheel and the blank,the deformation of the continuous small area is accumulated,and finally a free form plastic forming technique without forming constraints is formed.Based on the analysis of rack cold rolling forming on the basis of the principle,the method of theoretical analysis,finite element numerical simulation and experimental research is united to systematically study on the deforming force,defect of scale on the surface of formed parts,springback and residual stress of rack cold rolling forming.And the basic characteristics that cold roll forming parts is explored.It provides technical support for its application,and it has important theoretical significance and application value.The metal flow pattern forming process under forward and reverse beating is analyzed,and the coordinate system of rack cold roll-beating is established.Based on the characteristic of rack cold roll-beating,the reasonable constitutive relation and unit type are selected,and the simulation parameters are analyzed and set up.A finite element simulation model which coincides with the actual process of rack cold roll-beating is established.The influence of mass magnification coefficient on the deformation force and forming profile in rack cold roll-beating process is studied.The threshold of mass magnification coefficient in rack cold roll-beating process simulation is given.An analytic model for the scale of the surface roughness and the width between the scales of the workpiece under different roll beating methods is established,and the numerical solution of the height of the scale in different rolling ways is studied,which can obtain influence of revolution speed and horizontal feed speed on the height of scale.A method for correcting the analytical model by finite element simulation results is proposed,which improves the calculation accuracy of the theoretical model and provides a theoretical basis for the control of the surface quality of cold roll-beating process parts.An analytical method based on the principal stress method for solving the single roll deformation force during the cold rolling stability stage is presented.The theoretical formulas for calculating the radial and tangential deformation forces in forming process are obtained by theoretical deduction.With the study of change law of deformation force under different roll modes,the deformation force in the rack cold roll-beating process is simulated and the change law of the deformation force during the whole roll forming process is analyzed.By comparing the simulation with the analytical results,the validity of the analytical model of deformation force is confirmed,and the variation law of the deformation force under different rolling modes is revealed.A finite element dynamic and static simulation model of rack cold roll-beating process is established.According to the simulation results,the characteristics of deformation springback in the rack cold roll-beating process are analyzed.The effects of different roll depth,roll speed and different materials on the tangential,axial and radial changes in the law is studied.The dynamic simulation results are analyzed statistically,and the elasticity of the deformation is obtained.The springback law of the local deformation under the condition of high impact and high strain rate is found,which provides the basis for the effective control of the precision of the cold roll forming.The residual stress axial and radial analysis paths are established.The influence of different process parameters and materials on the residual stress of the workpiece under the conditions of cold rolling was studied.The analysis and variation of the surface and internal residual stress of the workpiece were obtained with different rolling depth,rolling speed and different materials.The actual test results verify the correctness of the simulation analysis,and provide a reference for the effective control of the residual stress on the quality of the forming parts.The rack cold roll-beating device is developed,and the test scheme of rack cold roll-beating is made.Through a large number of experiments,both the forming forces under different rolling methods,technological conditions and the parameters such as the scale height,the profile of the cogging section and the surface residual stress were obtained.It is found that the experimental results of the forming force,the surface scale height,the material rebound and the surface residual stress during the roll forming process are similar to the theoretical analysis and the numerical simulation results,and the variation rules are consistent with each other which can validate the simulation model and the correctness of the theoretical calculation method.It provides theoretical basis for further research and application of this technology.