Research On Drawing Process Of Copper Plate And Aluminum Plate Based On Electronically Controlled Permanent Magnet Blank-holder Technology

For a long time,the control of the blank-holder force is one of the key and difficult problems in the sheet metal forming process,and has been highly valued by scholars all over the world.The research on the blank holder force mainly includes different blanking method,variable pressure side force system,critical blank holder force stroke curve etc.Aiming at automate and intelligent control of the blanking force to meet the needs of efficient,energy efficient,green and modern forming processes.Applying the electronically controlled permanent magnet technology to the blank holder force control is to convert the magnetic attraction force of the electronically controlled permanent magnet chuck into the blanking force of the presser ring,and act on the flange region of the slab to realize the deep drawing process.For the deep drawing of non-ferromagnetic materials such as copper plate and aluminum plate,part of the magnetic pole unit can be arranged in the flange deformation zone,so that the mold structure is more compact and the blanking force is larger.The deep drawing of cylindrical parts of copper and aluminum plates,the loading and control of the blanking force is realized by electronically controlled permanent magnet technology.The main research contents include:the analysis of the principle of magnetic circuit of chucks,hysteresis loop,magnetic energy loss.the selection of high magnetic energy magnetic pole material and theoretical calculation of magnet structural parameters.The optimization design of magnetic pole structure parameters.The influence of chucks structure parameters on electromagnetic field and magnetic attraction,and the air gap of the crimping device on the blanking force is analyzed,to complete the design of the magnetic pad and the drawing die.The deep drawing experiment of the cylindrical parts of the copper plate and the aluminum plate and the deep drawing process of the plate.It is verified that the crimping device is applicable to the method of drawing and crimping copper plates and aluminum plates.First,the mechanics theory and defects of the deep-drawing blank are analyzed,and the types of magnetic poles used for deep drawing non-ferromagnetic materials were determined.Analyze the magnetic circuit principle of the chuck,the principle and measurement of the hysteresis loop,and the magnetic loss of the chuck.Select the high magnetic energy magnetic pole material and study the relationship between the magnetic pole structure parameters,and the structural parameters of the magnetic materials are calculated.Secondly,a new optimization method based on DOE for the magnetic pole parameters of electronically controlled permanent magnet chucks is proposed.According to the methods of finite element analysis,theoretical calculation,experimental verification,etc,the magnetic pole model of 50mm×50mm is selected,and the method of combining finite element orthogonal simulation experiment with high-precision regression equation is carried out.Finally,under the magnetic material,the size of the NdFeB is 50 mm×9.4mm×10 mm,the size of the ANiCo is 41 mm×41 mm×12.5 mm,and the thickness of the magnetic pole block is 17.2 mm.With the same optimization method,the pulse current was determined to be 19A,the thickness of the copper wire was 0.5 mm,the number of turns of the coil was 255 laps,and the height of the coil was 12 mm.The experimental verification and comparison with the simulation results show that the magnetic attraction per unit area is 161.23N/cm~2 and 167.75N/cm~2,respectively,and the chuck can achieve complete demagnetization,which proves the feasibility of the optimization method.Then,according to the different layout forms of the magnetic pole unit,the finite element simulation method is used and select of the air gap between the suction plate and the suction cup to be 0.3 mm,and the influence of the structural parameters of the suction cup on the electromagnetic field and magnetic attraction force is studied.The influence of blank thickness on the blank holder force is obtained.According to the air gap simulation results,an improved scheme is proposed for the non-contact area structure of the blank and the upper surface of chucks.A new type of assembled electronically controlled permanent magnet blank holder device is proposed to achieve the flatness and wear resistance of the upper surface of chucks.According to the electromagnetic simulation analysis of chucks,the finite element stress analysis of the initial position of the slab drawing is carried out,and the simulation drawing of the sheet drawing process under the condition of the blank holder force is finally obtained.Finally,an electronically controlled permanent magnet blank-holder device was fabricated.Under the existing experimental conditions,H62 and AA6061non-ferromagnetic materials were selected,and the slab thickness was 0.5 mm and the diameter was 90 mm.Taking a cylindrical piece with a diameter of 50 mm as an example,a deep drawing experiment of an electronically controlled permanent magnet crimping edge was performed.When the number of controller stages is 9 grades,the full drawing of the aluminum plate can be realized,and when the number of controller stages is 11 grades,the full drawing of the copper plate can be realized.The problem of wrinkling and cracking in the deep drawing process was studied,and the control process of the blanking force and the forming effect of the sheet were analyzed.The results show that the new electronically controlled permanent magnet crimping device can be applied to the drawing process of copper plate and aluminum plate.