End-effect Numerical Simulation Analysis In Continuously Flexible Forming

Plate forming technology, namely plate rolling technology, is widely usednowadays. It’s a continuously bending process to form plate by three points. Andcontinuous forming technology is a simple, effective, and flexible three-dimensionplate forming technology. It combines with traditional plate forming technology andmulti-point forming technology. Flexible rolling technology has the advantages oflow-cost, simple equipment, efficiency and automation, and has a good applicationfuture.For the feasibility in actual production, this paper has been quantitativelyanalysed the straight roll forming process, and described it by mathematics andmechanics theory. To check the correctness of concluded computational formulas,this paper established a finite-element model and compared the results of numericalsimulation and the concluded computational formula. And analysed the variation ofend-effect in flexible rolling process by comparative analysis of simulation results.The main research contents and consequences are concluded as follows:1. Computational theory analysis in straight roll forming processVia mathematic relation between forming roll and sheet metal, and mechanicsrelation of bending moments and springback in plate rolling process, the curvatureformulas and skew curve formulas of stable forming area, beginning forming areaand finishing forming area have been concluded in this process. Furthermore, thispaper calculated the parameters value in these formulas and drew out the figure ofthe formulas by MATLAB. From the concluded computational formulas, theconclusion can be deduced as follows: firstly, in stable forming process, thecurvatures of elastic loading stage increase linearly, the curvatures of elastic-plasticloading stage increase quickly and nonlinearly, and the curvatures of unloadingdecrease linearly. Secondly, in beginning end and finishing end forming stage, thecurvatures of elastic-plastic unloading stage decrease nonlinearly until the curvatureto0, and keep the0value in elastic unloading stage.2. Establishing finite-element model, Compare the results betweensimulations and computational formulasThis paper has established finite-element model continuous three-dimension surface flexible rolling process model and straight rolling process model inABAQUS. And it introduced the procedure of establishing finite-element model. Viaactual production, comparative analysis and software comprehension, the model hasbeen set the material element, material property, model steps, interaction property,contact property, boundary condition, algorithm option, local coordinate system etc.Considering the characteristics of straight rolling model and flexible rolling model,the various parameters have been set.To check the correctness of the three stages in straight roll forming process, asstable forming process, beginning forming process and finishing forming process,the simulation results in ABAQUS and concluded straight rolling computationalformulas drew out by MATLAB have been compared. Via above compare, thecomparative results prove the seven computational formulas in the three stages ofstraight rolling process are correct.3. Analysis of end-effect in continuous forming processVia the analysis of spherical part end-effect, the conclusions have been get asfollows: in continuous forming process, the variation of longitude curvature is thesame as straight rolling in the end area. But the distribution of curvatures is not thesame. From the middle to the part edge, the curvatures of different longitude pathsare keep decreasing, the change of the curvatures become faster, the maximum valueof curvature is become bigger, the range to the maximum curvature is becomesmaller. In the middle area of part, the distribution of curvature is not equal asstraight rolling, it has a certain scope. From part center to the edge, the scopebecome bigger and dramatically. Via comparison of experimental part and simulationresults, the forming effects are the same.4. Analysis of latitude curvature in continuous forming processContinuous forming process finite-element model with different parameters hasbeen simulated. And via the compare of different results, some conclusions havebeen obtained as follows: firstly, with the increase of plate thickness, the curvature oflatitude is more closed to target curvature. With the increase of pressing distance,straight end is decreased, and latitude curvature is more closed to target curvature. Insaddle part forming process, although the pressing distance is different, the status ofplate end has no obvious change.