Simulation Study Of Size And Process Parameters On The Forming Quality Of Notched Rectangular Tube Of High Strength Steel In Rotary-Draw Bending

Because tubes can help develop lightweight,high-strength products and achieve low consumption,high efficiency,and precise manufacturing,they have become an essential direction in the research and development of advanced plastic processing technologies.Over the years,the manufacturing industry has increasingly focused on various special-shaped section tubes.A notched rectangular section tube,for example,offers the advantages of easy processing,strong pressure resistance,and effortless installation.As a result,it has become increasingly popular in various industries,including automobiles,shipbuilding,machine tools,construction machinery,and more.Despite the growing popularity of notched rectangular section tubes,little research has been conducted on the causes of various process defects and the factors affecting tube quality in the rotary-draw bending of high-strength steel.To prevent various process defects in the rotary-draw bending of high-strength steel notched rectangular section tubes,this study examines the impact of dimensional and process parameters on the quality of formed bent tube fittings.Numerical simulations are conducted using ABAQUS software to analyze the rotary-draw bending of Q345 high-strength steel notched rectangular section tubes at 90°.The study investigates the impact of four size parameters,including the wall thickness of the tube blank t₀,the ratio of notched width to cross-sectional width of the tube k₀/a,fillet radius of the tube blank r,and the width-height ratio a/h₀of the tube.The study also analyzes the impact of two process parameters,including the gap c between the mandrel and the tube blank,and the bending radius R.The effects of these parameters on the degree of thinning the wall thickness,the reduction rate of the notched width,the reduction rate of the middle surface height,and the rebound quantity are examined in detail.Additionally,this study evaluates the advantages and disadvantages of using rectangular and"convex"mandrels to form high-strength steel notched rectangular section tubes in rotary-draw bending by comparing the quality of the bent pipe fittings produced by both methods.The study provides a comprehensive analysis of the two mandrel types and their impact on the forming quality of high-strength steel notched rectangular section tubes.Overall,the study provides valuable insights into optimizing the rotary-draw bending process for high-strength steel notched rectangular section tubes to avoid defects and enhance the quality of the final product.The results are analyzed and obtained as follows:（1）The wall thickness of tube t₀has a significant effect on the reduction rateη_kof the notched width and the reduction rateη_hof the middle surface height of the cross-section of the notched rectangular bending fittings.With the increase of the wall thickness t₀of the tube,the maximum notched width reduction rateη_kmaxand the maximum middle height reduction rateη_hmaxof the bent tube fittings decreased,but the rebound angleΔθincreased.（2）Rate of the notched width to width of tube blank k₀/a had little effect onη_hmaxand the maximum wall thickness thinning rateΔ_1max,but with the increase of k₀/a,theη_kmaxandΔθof the bending parts decreased.（3）The increase of the fillet radius of tube blank r will lead to the increase ofη_kmaxbut have no significant effect on the changes the values ofΔ_1max,η_hmaxandΔθ.（4）The width-height ratio a/h₀of tube is the main factor affecting the forming quality of notched rectangular section tube in rotary-draw bending.With the gradual decrease of the values of a/h₀,Δ_1max,η_hmax,andη_kmaxof tube all increase gradually,while the value ofΔθdecreases.（5）With the increase of bending radius R of tube,the value ofΔ_1max,η_kmax,η_hmaxandΔθof tube all reduce significantly.（6）The increase of the gap c between mandrel and tube when the tube is formed around the bending mould will lead to the increase ofη_hmax,η_kmax,andΔθvalues of the bent tube,but the value of the maximum wall thickness-thinning rateΔ_1maxcan be reduced.（7）Compared with rectangular mandrels,the use of"convex"mandrels can effectively reduce theη_kmaxvalue of elbows,however,it will lead to an increase in the wall thickness and rebound angle of the notched side of the bending part,and in severe cases,it will lead to wrinkling.