Research On Clinching And Integral Forming Of Light-weight Components With Thickness Difference Using Rotary Tooling

Utilizing plastic forming to achieve plate clinching and integral thin-walled ribs components with differential thickness characteristics have significant advantages in improving the specific strength,specific rigidity and weight reduction of the structure.However,there are few related studies at present and there is also a lack of in-depth understanding of its deformation law.This paper first summarizes the clinching method of plate,and summarizes the forming method of rib plate and rib cylindrical components.In view of the large load and difficult deformation control of the existing lightweight component integral forming process,geometric analysis,finite element simulation and physical experiments were combined,in order to research the roller clinching based on the concept of "rotational forming" and the forming law of mesh rib plate and rib cylindrical members.The main contents are as follows:(1)Roller clinching is a variation of conventional clinching by using rotational tool movement.The joining quality of roller clinching is significantly affected by tooling geometries and motions.Considering the formation difference of joints at different locations,this paper investigated the deformation features of roller clinching of square joints,and utilized multiple linear regression analysis to optimize the processing parameters.It was found that roller geometry has significant impact on the formation of interlocks of the front/rear sides of joints,while the impact on the formation of lateral sides is less.(2)The clearance variation of front/rear sides decrease with the increase of roller diameters,meanwhile the separation clearance s at the front side after forming decreases.In the study,when the roll diameter is raised from 35 mm to 150 mm,the connection strength increases by 44%.Increase the diameter difference w of rollers,the squeezing degree of front side decrease,and the joining quality increase;however,the squeezing degree of rear side increase,then the joining quality of rear side and s decrease.In the sample,an increase in w by 3 mm enhanced the connection strength by 9%.Increase the clearance difference t between the rollers,the capability to contain metal increases in rear side;when t increases by 0.6 mm,the connection strength augments by 12%.The separation clearance s of front side is greatly affected by friction μ,roller diameter,w,and draft angle γ of the lower roller,while the effect of draft angle β of the upper roller on s is small.(3)For mesh rib plate,this paper proposes a method of forming ribs by roller rolling;for mesh rib cylindrical,this paper proposes a method of profiled roll cylindrical ring rolling.The new method combines volume forming with roll forging,partial forming,cylindrical ring rolling,etc.,and can form various types of components with different thick ribs.Compared with other methods,the new method has the advantages of high forming efficiency,good metal flow,high precision,and low load.(4)Shape of the deformation zone and restraining force of the die are closely related to roll forming warpage,filling dissatisfaction and partial draining.The width and height of the deformation zone increase,the filling rate increases,the warpage is reduced,the forming force increases,and the flow through is serious.The greater the restraining force of the die,the warpage is reduced.With the increment of radius R of the main roller and the friction coefficient μ and the pressing amount I,the filling rate becomes better and the warpage is reduced so the forming force increases.Under the same quality condition,increasing I within a certain range has a lower forming force rather than increasing R or μ.The reduction of rib spacing will increase the restraining force of lower mold and reduce the warpage.(5)The profiled roll cylindrical ring rolling has two stages: press-in and ring rolling.The slip won’t happen in press-in stage at the ribs,but the roots of the ribs are prone to folding.The situation is opposite at the non-rib position.In the ring rolling stage,there are often problems of misalignment,interference,folding,distortion and meshing instability.The difference between actual and theoretical meshing position is the root cause of the dislocation defect.By studying the non-misalignment conditions,deriving the prediction equation of the actual meshing line L 实 through analytical analysis,and combining with the minimum offset difference ΔX and the method of forced meshing,the misalignment can be effectively prevented.Improper design of longitudinal ribs will cause interference,and the interference can be prevented by controlling the appropriate gear pressure angle α;Folding is mostly caused by excessive accumulation of metal at the rear end.It can be avoided by enlarging the radius of the roller and reducing the depression;The meshing instability is caused by back slip,which cannot be avoided directly,but the method of calculating the average meshing ratio can be used to approximate the true value.