喻海良，学者凯发k8国际首页主页-凯发网

a new kind of numerical method, contact element method (cem) with two relative coordinates, has been proposed. there are two main characteristics in this method. first, meshing is based on the contact length between the rolls or between the work roll and the strip; second, two relative coordinates are established for every element depending on the contact objects. a matrix for analyzing the rolling process of a sendzimir mill has been established as well as a software sm4sm (setup models for sendzimir mill) by which the strip edge drop during rolling has been studied using the cem. the calculated results show that the strip edge drop will decrease when increasing the 1st intermediate roll (imr) taper slope and length, reducing the 1st imr shifting, increasing the roll j and the work roll crown, or increasing the tension stress; by contraries, the strip edge drop will increase. meanwhile, three methods (changing the work roll crown, changing the work roll edge rigidity, changing the pressure distribution on the work roll) for controlling the strip edge drop are discussed.

closure and growth of transverse cracks on slab surface severely affects the quality of rolled products. a finite element (fe)-based modeling on thermal and mechanical behavior of transverse cracks during hot rolling has been carried out using ls-dyna software. the behavior has been simulated at a range of crack sizes, crack open-angles, friction factor between roll and slab. the maximum compressive and tensile stress at crack tip during rolling, the crack open-angle and the crack height after rolling, and the temperature on crack surface during rolling were analyzed. the mechanism of crack behavior during rolling is discussed.

the present work introduces a new type of numerical analyzing method: the contact element method with two relative coordinates (cem). the main characteristic of the procedure is elements meshing on the basis of the contact length between objects and that each element has two relative coordinates. the ordinary expression of this procedure is dx[cxy(i)]=dy[cyx(i)]. through this method, the cem function of the 20-high sendzimir mill and the deflection function expression of every roll are obtained. a computational software sm4sm for the sendzimir mill has been developed, by which the deflection condition of rolls s, o, i, and a can be obviously seen. the results obtained by cem have also been compared to that by the finite element method.

the strip quality is affected by the shape and the distribution of inclusions. the investigation of inclusion deformation in rolling process is significant for understanding the deformation mechanism of inclusion and guiding production. in present work, the behavior of spherical non-metallic inclusions in type 304 stainless steel strips during multi-pass cold rolling has been simulated by 3d finite element method and updating geometric method. the shape of inclusions is obtained under a variety of the inclusion sizes and positions. the inclusions elongate along rolling direction and compress along strip thickness direction, but slightly change along strip width direction. when the inclusion diameter is less than 10 μm, the inclusion scarcely deforms. as the inclusion sizes increase, the inclusion deformation gradually increases. the inclusion deformation also increases with the inclusion approaching the strip surface. as the rolling pass increases, the differences of inclusion shapes increase under various inclusion sizes and positions. the inclusion profile after cold rolling calculated by simulation is consistent with that by experiments. finally, the relationship between the inclusion deformation and the crack generation is discussed.

three passes of slab rolling during vertical–horizontal rolling process were simulated with explicit dynamic fem by updating geometric method. simulation model of the next pass was built when the rolling geometry model was updated after previous pass was finished, changing roll gap, material attribution and boundary conditions. the calculated results of the slab shape are in good agreement with the experimental ones. it is shown that the explicit dynamic fem and updating geometric method can be used effectively to analyze the multi-passes of v–h rolling process.