Influence Of The Number Of Rollers On The Roll Forming Of The Curved Shape Of The Cylindrical Body

At present,curved revolving shape parts are used more and more widely in aerospace field,weapon equipment and civil products.Curved revolving shape cylinders are formed by traditional machining methods and spinning processes.These methods can hardly meet the requirements of high efficiency,low cost and less cutting for curved revolving shape cylinders.Roll extrusion can directly form the cylinder with curved revolving shape at one time.This paper mainly studies the influence of the number of rollers on the roll extrusion forming of the cylinder with curved revolving shape in the process of roll extrusion.Deform-3D numerical simulation software was used to simulate the forming of two-roll,three-roll and four-roll rolls.The effects of the number of rollers,punch speed,friction factor and roller diameter on the forming quality and accuracy of the cylinder with curved revolving shape and the force exerted on the punch and roller are studied and analyzed.The results show that:Two-roll one-roll extrusion die is extremely uneven,the radial height of flash increases obviously,and the radial top is pointed and thin.During the process of roll extrusion,the flash groove overflows,the height of roll extrusion is lower than the requirement of technological dimension,and serious folding occurs during the second roll extrusion;three-roll and four-roll one-roll extrusion die is relatively flat,the height of flash is lower than two-roll,and the surface of the second-roll extrusion is not folded.Defects such as cracks.The change of punch speed has little effect on the surface quality of roll extruded parts.When punch speed is the same,the minimum length of three-roll extruded parts in one pass and two passes is less than four rolls,the radial height of three-roll flash in one pass is greater than four rolls,the difference between punch force and four rolls is small,and the force on roll wheel is greater than four rolls.With the increase of punch speed,the force on punch and the radial force on roll wheel are almost unchanged.After secondary roll extrusion,there are no cracks and folding defects on the surface of roll extruded parts.When the friction factor is the same,the length of three-roll extrusion is less than four rolls,the radial height of three-roll flash is greater than four rolls.With the increase of friction factor,the force exerted on the punch and the radial force exerted on the roll will increase.The difference between the force exerted on the three-roll punch and the four-roll punch is small,and the radial force exerted on the three-roll wheel is about 28% higher than that on the four rolls;the force exerted on the two-roll punch and the four-roll will increase.The difference is small,the radial force of three rollers is greater than that of four rollers,and there are no cracks and folding defects on the surface of three rollers and four rollers.The change of roller diameter has little influence on roll extrusion.With the increase of roller diameter,the force of punch is unchanged,and the radial force on roll increases accordingly,and the increase range is less.When the increment of roller diameter is the same,the force on three-roll and four-roll punches is almost the same,and the radial force on three-roll is greater than four-roll;the minimum height of two-pass three-roll extrusion is less than four-roll,and the three-roll and four-roll punches are affected.The force is almost the same radial force.The radial force of the three rollers is greater than that of the four rollers.There are no cracks and folding defects on the surface of the roll extruded parts.According to the above research,the three-roll and four-roll extrusion forming experiments were carried out to verify the successful roll extrusion forming curve revolving cylinder parts.The three-roll and four-roll extrusion parts were measured and observed,and the metal folding was not found at the flying edge of the roll extrusion,which was in good agreement with the numerical simulation results.The surface quality and size of the roll extrusion parts met the requirements of the roll extrusion forming process.