Study On The Roll Extruding Forming Without Burr For Cylinder Parts With Curvilinear Rotating Shape

As a new technology of plastic processing, roll extruding forming combined the advantages of two kinds of plastic forming methods include roll forging and extrusion, cylinder parts with curvilinear rotating shape was formed directly through continuous local deformation. However, burr was formed inevitably at the nip of the two rollers in the roll extruding forming, which resulted in subsequent machining difficulties and hinder the application of this technology in actual production.A kind of new technology of the roll extruding forming without burr with two-pass is proposed. In this process, the burr-cavity is opened in the roll joints with two adjacent rollers.Cylinder with longitudinal burr on its outer wall is formed in the first pass, the next, blank rotaries a certain angle and passes into the second forming, make burr vertices and the lowest point of the roller groove contacted, thereby removing the burr formed in the first pass,the roll extruding forming of cylinder parts with curvilinear rotating shape is completed.Mechanical analysis of roll extruding forming process with mandrel is made using principal stress method, a mechanical model of roll extruding forming is established and the formula of roll extruding force was deduced. Forward slip model of roll extruding forming process with mandrel is established, which provides a theoretical basis for the design and optimization of rollers.Using Box-Behnken experimental design to design the key structural parameters of rollers in the no-burr roll extruding forming with two-pass, this optimal design is based uniformity of deformation in deburring process programme, a small sample simulation test with DEFORM-3D is operated, SPSS statistical software is used to establish the regression models between objective function (deformation uniformity factor) and design variables (opening angle of the burr-cavity2θ, corner radius of the burr-cavity r, distance between burr-cavity vertice and roller-groove center h), optimal parameter combination of various factors of is obtained.Through the establishment of dimensional finite element model of roll extrusion equipment rack, stress and displacement statics finite element analysis for roll extrusion equipment rack is operated by using ANSYS workbench.On the basis of the process optimization, comparative test of a direct roll extruding forming process and no-burr roll extruding forming with two-pass is performed for typical parts. Cylinder parts with curvilinear rotating shape is formed to verify that the previous theoretical studies, modeling and optimization design is correct.The new technology of the no-burr roll extruding forming with two-pass effectively solves the problem that roll joints prone to "flake burr" in a direct roll extruding forming process which will brings inconvenience for subsequent machining.This new technology provides an important reference for further research and promotion of roll extruding forming process.