Research On The Effect Mechanism Of Two-pass Roll Forming On The Forming Quality Of Rotary Shaped Cylinder

The roll forming process is a new process for the preparation of variable-wall-thickness curve-shaped cylindrical parts.Compared with the existing traditional methods,roll forming has the advantages of high material utilization,high production efficiency,and low production cost.Can effectively retain the metal streamline,greatly improving the reliability of the product.In this paper,based on the plastic forming technology,the formula for calculating the front slip ratio of the roll forming rotary shape cylinder parts is deduced.Pro-Engineer 3D was used to construct the three-dimensional roll forming model,and Deform-3D finite element simulation software was used for simulation.Design different opening angles of the flashing groove of the roller,change the friction coefficient between the roller and the blank,and the friction coefficient between the blank and the punch to simulate the cold forming of the pure aluminum blank;change the preheating temperature of the mold and the working speed of the punch to the 40 Cr blank Carrying out thermoforming simulation and using response surface method to optimize the process parameters of roll forming,the results show that:When the opening angle of the flash groove is increased from 50° to 110°,the uniform deformation coefficient of the metal in the flash groove decreases first and then increases;when the opening angle of the flash groove is 50°,the metal deformation and deformation of the flash groove The most uneven,the fold at the flash edge after the second pass shaping;as the opening angle of the flash groove increases,the height of the flash edge gradually decreases,and the folding disappears after the opening angle of the flash groove is greater than 90°;when the flash When the slot opening angle is 110°,the wall thickness of the blank is uneven after the second pass shaping.In summary,when the opening angle of the flashgroove is about 90°,the forming quality is the best.Two roller groove design methods were obtained in the design of the first pass roller:using the bite angle as the neutral angle to calculate the front slip rate of the roller middle is relatively simple,but the effect of friction is not considered;the forward slip after correction is used The calculation of the neutral angle calculated by the rate formula and the theoretical angle is complicated,but the influence of friction is considered.The length of the edge of the circumferential groove of the roller wheel during the second round of roll extrusion can be designed to be equal to the axial length required by the workpiece after roll extrusion.In 40 Cr thermoforming,as the mold preheating temperature increases,the load of the punch and the roller gradually decreases,and finally it stabilizes,the height of the "boss" at the billet mouth gradually decreases,and each preheating temperature increases by 200?,the height of the "boss" decreases by about 0.6mm;As the working speed of the punch increases,the load of the punch and the roller gradually decreases,and finally it stabilizes.The height of the "boss" of the blank mouth decreases first and then increases,The height of the punch is the lowest when the working speed is 40mm/s.The optimized experimental scheme is designed by the method of curved surface response,the mechanism of the influence of process parameters on the roller forming cylinder parts is obtained,and the correlation model is established.On the basis of theoretical and simulation simulations,the roll forming test was carried out to obtain variable-thickness rotating-shape cylindrical parts with no flash and no folds.The measured blank forming dimensions were within the process error range,confirming the previous simulation and theory The correctness of the analysis provides a theoretical basis for the development of the roll forming process.