Research On Electromagnetic Tube Flanging With Radial-axial Electromagnetic Force Loading

Flanging is one of the very important procedures in aerospace,transportation,large machinery and other processing processes,which directly affects the forming accuracy of parts and the subsequent assembly and welding quality.Aluminum alloys have lower plasticity at room temperature.The low forming plasticity of aluminum alloy at room temperature,so it is easy to rebound and tear,which leads to the bottleneck of traditional flanging process in the field of aluminum alloy material processing.Therefore,electromagnetic forming technology is widely studied as an advanced method for driving high-rate deformation of metal workpieces by using pulsed electromagnetic force.In the past research on the tube electromagnetic forming,it is generally considered that the electromagnetic force application method is single,and the flanging is mainly included radial electromagnetic force.However,during the tube electromagnetic flanging,it is not only bulged radially by the electromagnetic force,but also expanded axially by the constraints of the mold,the force field requirements are more complex.Therefore,based on the consideration of radial electromagnetic force,it is necessary to further analyze the influence mechanism of axial electromagnetic force and the required force field requirements.For this reason,this paper proposes a electromagnetic tube flanging technology with radial-axial electromagnetic force loading,and analyzes the electromagnetic force distribution characteristics,which intends to effectively solve the problem of unmatched force field requirements.Firstly,based on the electromagnetic tube flanging process with single coil,a fully coupled numerical simulation model is established,and the coupling relationship among the discharge voltage,coil turns,the relative spatial position and the electromagnetic force is analyzed in detail.Through simulation analysis,it is found that not a single radial or axial electromagnetic force plays a decisive role in flanging of the pipe,The tube flanging effect is closely related to the magnitude of the radial electromagnetic force and the axial electromagnetic force and the distribution of the force field:(1)When the radial electromagnetic force is insufficient,increasing the axial electromagnetic force properly can get better flanging effect.(2)By changing the relative position of coil and tube and adjusting the distribution of radial and axial electromagnetic force,the more matching force field can be obtained.(3)when the best matching force field is obtained by changing the parameters of the system,the electromagnetic tube flanging has the best forming effect and the minimum total electric energy is needed.Next,based on the tube electromagnetic flanging experiment scheme with single coil,two high-intensity discharge coils with different turns are designed and manufactured,and other experimental facilities are prepared and debugged,and experimental research is carried out.In the experiment,taking A6061-O aluminum alloy tube as the research object,the flanging effect of 6-turns coil is better than that of 4-turns coil under different discharge voltage.And the discharge voltage required for the 6-turn coil to complete flanging is the minimum,so the experimental results are in line with the theoretical expectations.Finally,the method of double coil electromagnetic tube flanging is firstly proposed,The radial and axial electromagnetic force required for electromagnetic flanging is provided by two coils respectively.At this time,the electromagnetic force is flexible and controllable,and the force field required for tube flanging can also be matched in multi-dimensional ways.This method can be applied to the tube flanging process with special requirements,and a new way is explored for the further application of electromagnetic tube flanging technology.