Papers by Author: Lan Wei Hu

Abstract: A 3-D thermal-mechanical model was built to simulate the hot rolling process of medium plate, with the aid of nonlinear commercial FE code MSC.SuperForm on a company's actual process parameters. The hot rolling process of single-pass which slab thickness is 180mm was simulated, and the influence of pass reduction on metal flow, stress-strain field, contact stress and rolling force were researched. The study revealed that pass reduction should be at least 20% by increase depress in pass in addition to rolling efficiency. As that, rolling efficiency be increased, roll contact stress be brought down, and its service life be prolonged. And metal plastic strain enhanced, metal flow increased, but its strain field non-uniformly distributed, metal flow and plastic deformation would be strengthen by increase pass reduction, and the lateral broadening in the head is bigger than that in the tail.

Abstract: With the aid of commercial FE code MSC.SuperForm, the rolling process of Accu-Roll mill is simulated and the influence of guide disc postposition on the value of outside diameter expansion of elongated shell, force parameters and twist deformation of the workpiece are analyzed in detail. Analysis results indicate that the value of outside diameter expansion of elongated shell, guide disc force and the axial force of mandrel decrease when the value of guide disc postposition increases, but separating force and twist deformation of the workpiece increase, which provides scientific guidance for designing Accu-Roll mill and setting adjustment parameters.

Abstract: With the aid of commercial FE code MSC.SuperForm, the structural steel tube continuous rolling process of a typical hollow tube specification 152.5×12.5mm is simulated based on Bao Steel 152.5 main pass sequence of 140mm 8-stand mandrel mill, and the distribution characteristics of stress/strain, outline lateral spread, temperature changes of workpiece in continuous rolling process and distribution of stress/strain, friction of workpiece in deformation zone are analyzed. Analysis results indicate that deformation of workpiece along the width of the groove, especially at the top and the bottom of the groove is highly inhomogeneous due to the unequal draught and the longitudinal stress of special position (the top and the bottom of the groove) of workpiece is always an alternate state, in a tensile-compressive-tensile manner, and has a distinct rule. In the first stand, outline dimension of workpiece gradually increases during reducing process and early stage of wall thickness reduction, but it gradually decreases during middle-late stage of wall thickness reduction and tends towards stability at last. It is inhomogeneous that distribution of unit compressive stress and longitudinal strain of workpiece in deformation zone, and contact stress and total equivalent plastic strain are maximal in inner surface of workpiece contacting with mandrel. Temperature difference between the outer and the inner surfaces of workpiece is obvious.

Abstract: The Fomichev plug is of characteristic producing equal unit-reduction of wall thickness along its perforation section during seamless tube piercing. This paper introduces the design of a novel Fomichev plug based upon the analysis of roll opening, taking into account for both feed angle and toe angle of a cone type piercer, then presents a 3-D coupled thermo-mechanical simulation of the novel Fomichev Plug’s performance characteristic during cone-roll piercing process, with the aid of FE code MSC.SuperForm. In comparison with conventional plugs, as FEM simulation result shows that the new plug makes the metal deformation distribute uniformly along its perforation section, which brings about well-distributed plug wear. The novel Fomichev plug is able to decrease the slip between the roll and workpiece and avoid rolling block owing to its smaller plug force, which can increase piercing efficiency so, moreover, analyzing stress distribution, it’s more suitable for metal deformation with fewer defects in tube piercing, makes resistance to metal elongation smaller, reduces wedge cleaving to tube billet, and prevents lamination defects during piercing high-alloy billet.

Abstract: Concerning the 3-roll skew rolling process of round billets, a 3-D thermo-mechanical coupled simulation is performed with the aid of commercial FE code MSC.SuperForm. The influence of the feed angle and inlet cone angle of the roll on the strain and damage filed are investigated. It is found that the distribution pattern of the equivalent plastic strain in the longitudinal section of the billet presents U-shape, and that the feed angle and inlet cone angle of the roll make difference in the gradient of deformation intensity in radial direction of round billet. The ring-shaped distribution of the damage field in transverse cross section of the billet indicates a high tendency for the ring-shaped inner crack to occur, instead of the center crack appearing in 2-roll skew rolling of round billet. The results show that the critical parameters to control the ring-shaped crack during the 3-roll skew rolling process are the feed angle and inlet surface cone angle of the roll. It should be avoided to use too large feed angles so as to reduce the tendency of annular inner crack in the actual rolling of high-alloy steels with poor hot workability.