Study On Deformation Rules Of Tube And Roll Design Methods In Roll Forming Process Of High-Strength Steel Automobile Drive Shaft Pipe

Automobile drive shaft pipe is an important part of the transmission system.Many companies generally use the ordinary steel with yield strength of 480MPa to manufacture the shaft tube for large commercial vehicles.In order to meet the mechanical performance requirements,the wall thickness of shaft pipe is a bit large,which affects the car lightweight.It has many advantages using high-strength steel instead of ordinary steel,such as good mechanical properties,energy-saving,emission reduction,material saving and so on.High-strength steel shaft pipe is generally manufactured by using roll forming and high-frequency welding process.Roll forming process is the basic and important forming stage which have a serious impact on the follow-up welding quality.Therefore,it is very significant to study the roll forming process of high strength steel for automobile drive shaft tube.In roll forming process,the deformation of slab is complicated,which involves the nonlinearity of material,geometry and contact.The roll forming is more difficult than ordinary steel because of high strength,big rebound,poor plastic,hard to weld of high-strength steel.There are many factors that affect the roll forming of high strength steel,including roll design,process parameters and so on.The roll design is closely related to the slab deformation process and has a key influence on the quality of pipe forming.Therefore,studying on the roll design and slab deformation,and revealing the relationship between the roller shape and the forming quality of high strength steel in roll forming is of great significance for the control of springback,the edge condition of tube,forming quality and subsequent welding quality.This paper mainly focuses on the roll design,the overall deformation result and the edge forming rule of slab in roll forming.Based on ABAQUS simulation software,a simplified method and parameter setting are studied and the roll forming simulation model is established for high-strength steel roll forming of Φ120 drive shaft pipe with the material of 700QZ.Experiments are carried out and the cross-section shape,opening width and longitudinal depth of the slab are compared and verified.The common double-radius method is used to design the roller shape of Φ134 shaft pipe with high-strength steel.The deformation rules,the stress-strain distribution and the forming problems is revealed,such as the high stress strain,slab forming interference and so on.The first optimization method of roll design is put forward for forming problems,such as design of roller gap,vertical roller and closed roller.The stress concentration in vertical roller group and the unreasonable deformation distribution also exist in the first optimization method.In the second optimization method,the W roll design is studied and applied to the forming of high strength steel pipe.A combination forming system with double W roller and double radius roller are established,which improves deformation distribution and relieves the stress concentration in roll forming.Aiming at the deformation characteristics of high strength steel and the problems in ordinary double-radius forming,such as uneven distribution of stress and strain,stress concentration in vertical roller group,a new three-radius roll design method is proposed.And a detailed roll design proposal is carried out for Φ134 shaft pipe as an example.The range and the distribution uniformity of stress and strain,the variation rule of the thickness of the slab and the stress distribution in the vertical roller group are analyzed systematically.Compared with the ordinary double-radius method,the advantage of the three radius method on the roll forming of the high strength steel is obvious,such as achieving uniform deformation of slab and improving the stress concentration in vertical roller group and so on.The application of single pass W and double pass W in three-radius forming method is studied.The stress-strain distribution and the stress range of slab in vertical roller group in double W method is studied systematically which provides a new way for roll design of the high-strength steel drive shaft pipe.The deformation range of several forming methods in the vertical roller group is analyzed and compared,and the relationship between the deformation of slab and the concentration of regional stress is revealed.The basic rules and methods of parallel edge docking and edge deformation control during roll forming are studied.The influence of edge forming roller and W forming roller on the edge forming of slab is compared and analyzed.The distribution of strain in inner and outer walls of solid slab in double W rollers is studied.The concept of relative deformation of inner and outer wall of slab is proposed and it has been compared under different roll design methods.The influence rules of different initial roller shapes on parallel edge docking is summarized.The contact and force state of slab in single-radius and double-radius vertical rollers is analyzed,and reasonable design advice is given for double-radius and three-radius vertical rollers in order to avoid stress concentration and control springback.This paper analyzes the shortcomings for edge control of the ordinary single-radius closed roller,and puts forward the design method of double-radius closed roller considering the elongation of the slab and the edge control,which provides a reference for the edge control in roll forming.