Research On Push Bending Process Of Stainless Thin-wall Tubes

With the requirements of strong toughness light-weight, low energy consumption,high efficiency and precision manufacturing, the thin-walled tube elbows are widelyused in the Aerospace and High-speed rail. However, the half-tube stamping andwelding are used to form the thin-wall tube elbows at present, by which the weight ofproducts can’t be reduced, and the overall performance is also affected. In this paperthe cold push bending of1Cr18Ni9Ti tube (Φ30mm×0.3mm) with steel ball fillers isintroduced. Effect of parameters on forming quality and wall thickness distribution isresearched by theoretical analysis, finite element simulation and experiments, whichinvolves:(1) Mechanical analysis of process, force distribution of ball fillers, designing ofpush bending die.(2) Finite element simulation of push bending process; effect of processparameters on workpiece quality, wall thickness distribution and buckling; simulationof non-uniform internal pressure with uniform loading and non-uniform loading. It isshown that15MPa internal pressure,0.2friction coefficient and non-uniform loadingwork best.(3) Experiment of push bending with steel ball fillers in the condition ofoptimizing process parameters given by finite element simulation. effect of filler’ssize, reverse pressure, lubrication conditions on the axial wall thickness distribution ofinside and outside, circumferential wall thickness distribution, and ovalization. It isshown that12~15MPa reverse pressure, mixture of0.7mm and1.2mm steel ballsize(1:3), and MoS2lubricant are best.It is demonstrated that the cold push bending with steel ball fillers can be used toform the thin-walled tube elbows, which possess the smooth surface, uniform wallthickness distribution and ovalization below3%.