Advanced Materials Research Vols. 941-944

Abstract: The hot rolled strip thickness accuracy sometimes can not be guaranteed after a long time for waiting for slabs or other reasons. The reason is when rolling, the rollgap adaptive model has considered the thermal expansion of the roll. So when rolling is restarted, thermal expansion of the rolls must be cleared in order to accurately calculate the setup rollgap value. The finite element software ANSYS is used to calculate the temperature field and thermal expansion amount of the rolls in the rolling process. Application results show that this method can improve the accuracy of strip thickness.

Abstract: Thickness model adaption plays a important role in obtaining strip with high thickness precision. In order to improve the thickness precision, a complete thickness model adaption system has been designed for every specific model used in the setup system including gap position model, temperature model, rolling force model. Snapshot data and stretch equation are used to adapt gap position. Forced convection coefficient is selected as adaption parameter. A deformation resistance-based fitting quadratic curve is proposed in rolling force adaption, it can be inherited to any other thick range class and a quick thickness adaption method is introduced. Application results show that this adaptive system is with high accuracy, quick adaption and high stability.

Abstract: The filming mechanism and producing process of water-soluble plastic film is introduced in this paper. The principle and application of tension and correction of filming steel strip on hydrosol salivation machine is discussed systemically.

Abstract: Taking the upper strip of automobile doorframe which is complex profiles roll bending part of high-strength steel welded blanks as the research object, and then to Investigate its three-dimensional flexible stretch-bending formability under force control mode; the law of tensile force and clamp rotation angles’ influences on forming precision of the product is obtained. The results show that the springback of the line contour precision is largely affected by the comprehensive impact of tensile force and the clamp rotation angles, the values mentioned above reached minimum when the tensile force is 1.1 times the material yield strength, the springback will increase when greater or less than this value. Because of the surface torsion springback, internal and external surface contour accuracy mainly affected by the stage rotation angle when the profile bending curvature is large enough, and the effect is not obvious when the bending curvature is small.

Abstract: This paper adopts the method of multi-phase flow to simulate the extrusion process of single-screw extruder based on different screw speed by using the finite element analysis software, and get the conclusion that the screw speed has a significant effect on the extrusion quality and outlet pressure of the single-screw extruder. With the increase of the screw speed, the extrusion quality of the single-screw extruder gets worse and the outlet pressure of the single-screw extruder increases.

Abstract: In the automotive industry, hot stamping of ultra-high strength steel offers the possibility to reduce vehicle weight and enhance safety performance. However, the imperfect technology restricts its application. To investigate the hot stamping technology further, numerical simulation and forming experiment were made in this paper with a door beam as an example. After process parameters analysis, the evolution of sheet during the whole process were predicted through the simulation, according which the microstructure of the part were full martensite and no fracture was produced. A door beam was well-formed in the experiment based on the results of simulation, and then a series of tests as metallographic observation, hardness test, tensile test and side impact test were carried out, studying its performance in practice.

Abstract: The governing equations and the finite element model for the coupled thermo-mechanical multi-pass vertical-horizontal rolling process of a zircaloy strip are established. Considering the temperature-dependent and strain rate-dependent constitutive relation of zircaloy, the numerical simulation of the three-pass V-H rolling process is realized by the coupled thermo-mechanical dynamic explicit finite element method. The computational results such as the plastic deformation, the size variations and the temperature variations in three passes are discussed. The research results indicate that edging by vertical roller benefits improving the sizes of the strip and the temperature variations are rather obvious during the three-pass hot rolling process. The research provides experience and foundations for the FEM simulation of the hot rolling process of composite slabs for nuclear fuel elements.

Abstract: A new kind of binder was developed in extrusion molding. It included four ingredients: ethylene glycol acetate (60%~85% (mass/mass, as follows)), ethyl cellulose (10%~30%), ethylene glycol polyoxyethylene ether (5%~10%), polyethylene glycol stearate (0.8%~3%). The components of binder were compatible with thermodynamic conditions, so the binder was well-distributed in molecule level. The new binder is actual nontoxic, secure and environmentally friendly. The forming property of the binder is so excellent that it can load 54% ~ 56% (vol. /vol.) cemented carbide powders. The rods produced by this new binder provide high strength, stable performance, homogeneous microstructure.

Abstract: In order to obtain the best position of mid-roll shift, this paper studies the effect of different mid-roll shift position on the strip flatness of CVC 6-H mill. Strip element variation method and influence function method are put forward to analyze the effect of mid-roll shift on strip flatness. The results show the CVC 6-H mill is able to get good strip shape. The best shift position is obtained from the calculation results. The conclusion has a good significance for the practical application.

Abstract: It is investigated that effect of steel strip-feeding ratio and superheat degree of molten steel on solidification structure of ingot by the steel strip-feeding experiment in the mold. The results show that: at the same superheat, with the increase of feeding ratio, the area proportion of equiaxed grain zone increases and the average size of equiaxed grain decreases, and at the same feeding ratio, the higher the superheat is, the smaller the proportion of equiaxed grain zone is, and the larger the average grain size is.