Simulation and Forming of Hot Gas Pressure Bending for TC4 Titanium Alloy Bent Tube
The titanium alloy ring-shaped fuel tank is the key structure of the thin shell member of the upper stage of the launch vehicle.The new generation of fuel tanks requires higher space utilisation,so the bent tube is used instead of multiple spherical tank combinations,which improves the space utilisation by 58.64％.The bent tube has the forming difficulties of large size,ultra-thin,and difficult to deform the material,and the reliability of the traditional block-welding structure is poor.Based on this,this paper proposed a hot forming process of bent tube hot gas pressure bending,a built-in VUMAT subroutine embedded in the material constitutive model of titanium alloy bent tube hot gas pressure bending simulation model was developed.The variation rules of wall thickness and die sticking degree of hot gas pressure bending of titanium alloy bent tube under different process parameters were investigated.Taking the wall thickness reduction rate of the bent tube and the maximum deformation rate of the cross-section as the criterion,the hot gas pressure bending process window diagram of the internal pressure of the support and the temperature of the tube was established,and the optimal process parameters were determined.A TC4 titanium alloy bent tube hot gas pressure bending forming device was constructed.A full size titanium alloy bent tube was manufactured.The bent tube has a mid-diameter of 2692 mm,a cross-section diameter of 500 mm,a wall thickness of 2 mm,and a high diameter-to-thickness ratio of 250,and the difference between the actual component mid-diameter size and the target size is 11mm,and the maximum thickening rate of the intrados side of the bent tube is 11.5％,and the maximum thinning rate of the extrados side of the bent tube is 8.3％,tensile strength and average grain size basically are better than the design specification.
TC4 titanium alloybent tubehot gas formingfinite element simulation
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