Simulation Analysis Of Deep Hole Friction Thermoforming Of Thin Plate And Thin-walled Tube

The processing of deep hole with even wall thickness through sheet is a green and specific machining method differs from traditional hole processing methods.In this paper,by means of the frictional heat generated by the rotation between drilling tool and workpiece,to reduce the deforming resistance firstly heated up and softened the material at pore-forming zone,then made the sheet perforated and forming a hole.And the hole was a deep hole with equal wall thickness because of the squeeze between tooling and drilling tool.There would be no chips generated for the process was conducted using metal plasticity itself.And for the wall thickness of formed hole was about 3 times of the sheet thickness,which made the stress distribution more uniform,and a better structure performance of material grain was obtained because of the recrystallization generated by high temperature squeezing.Through the simulative analysis and research on hole formed by frictional heat of thin-walled sheet,the low efficiency and high energy consumption problems can be well solved and unthreaded holes with higher quality can also be obtained.Therefore,the main research contents are as follows:Firstly,based on the Markov variational principle,a rigid-plastic finite element model of deep hole with equal wall thickness was built.The forming features of deep hole with equal wall thickness were analyzed,the tooling was designed and the tooling material was selected as well.Then a heat transfer model of deep-hole forming with equal wall thickness was also established to solve the heat transfer coefficient.Secondly,the extrusion model of material at forming area was built based on upper bound method,and the temperature field model was also established based on Galerkin method.Meanwhile,using the forward Euler method to solve the coupled thermo-mechanical model and single-factor simulation and analysis were carried out by DEFORM software.Then,the variation of temperature field in pore-formingregion was analyzed by using point-tracking method,and the process parameters were also optimized and analyzed.Deep hole forming test was designed and conducted,the surface quality at hole-forming zone in the experiment result was detected and the influence of thermo-force interaction on surface quality of formed hole was studied.The simulation results were compared with experimental result to verify the accuracy of simulation model.Finally,based on the integral method,theoretical model of radial ultimate load of thin walled tube was established.Single-factor simulation analysis on hole formed by frictional heat through thin-walled tube was carried out by using DEFORM software,the force,temperature and light hole morphology result from two distinct parameters simulations were contrasted and analyzed.The variation regularity of hole-formed axial force and interactive relationship between force and heat were summarized,which verified the feasibility of forming hole by frictional heat through thin-walled tube.