Roughing process

Roughing stage is the main task of the slab or flat ingot broadening to the required width and extension of big compression is carried out. Under conditions of raw material and product requirements, and can have a variety of rolling method to choose. These methods are all longitudinal rolling method, integrated method of rolling, cross rolling method, Angle rolling - The longitudinal rolling method. A full longitudinal rolling method called direction of longitudinal rolling is an extension of the steel plate and raw materials ( Steel ingot and billet) With the direction of the vertical axis of rolling method. When raw material slightly greater than or equal to the width of the finished product when the width of the steel plate rolling, can need not broadening and longitudinal rolling mill directly into finished products, so that the whole longitudinal rolling method. Full longitudinal rolling method because of its simple operation so high yield, when rolling ingot ingot head defect does not extend to the length of the steel plate. But the whole longitudinal rolling method because in rolling ( Included in the blooming mill breakdown) Rolled piece extending along a side all the time, segregation and inclusions in the steel shows obvious zonal distribution, bring the anisotropy of the microstructure and mechanical properties of steel plate, the lateral performance ( Especially impact performance) Reduced. Full longitudinal rolling method due to rolling method, is used to adjust the width of the raw materials and steel organization performance of anisotropy, so not much has used in practical production. B comprehensive comprehensive method of rolling rolling rolling - namely The longitudinal rolling method. So-called is an extension of the steel plate rolling direction and material direction of the longitudinal axis of the vertical rolling ( As shown in figure 8 3 - 1) 。 Comprehensive rolling method, generally can be divided into three steps; The first longitudinal rolling 1 ~ 2 a flat slab of called roll forming; Then turn to the 900 rolling stretcher, extends to the required width the width of the slab, called broadening rolling; Longitudinal rolling line, and then turn to the 900, referred to as the extension of rolling. Synthesis of thick plate rolling method is a production of the most commonly used method. Its advantage is: the slab width is not restricted by the steel plate width, can choose according to the raw material situation, more flexible, as a result of rolled piece in lateral extension to a certain extent, improve the lateral performance of the steel plate. Usually casting billet size is less, so more suitable for the composite rolling method. But this method in the operation from raw material to the cross rolling, rolling to longitudinal rolling, rolling piece, there are two 90 rotation, so that production decreases, and easy to make the steel plate into the bucket, increase the cutting loss, lower yield. In addition because the slab transverse elongation is not big, make steel plate anisotropy to improve organization performance obvious enough, transverse still easy to low performance. C total rolling method total rolling method is the slab rolling rolling into finished products. This method can only be used for slab length is greater than or equal to the width of steel plate. When using continuous casting slab as raw material, adopts the method of rolling as well as the longitudinal rolling method is used to cause steel group performance obvious anisotropy. But if using slab as raw materials, due to the blooming when rolled piece when the direction of extension of the thick plate rolling perpendicular to the direction of extension of the anisotropy and thus greatly improve the steel plate, significantly improve the lateral performance of the steel plate. To make the steel performance is relatively uniform, should by the steel ingot to calculate the total deformation of the longitudinal and lateral pressure rate are equal. According to this principle can determine the slab thickness needed in heavy plate rolling. From the H0 / h1 = h1 + h1 according to the principle of choosing the slab thickness, h1 = ( H0h2) 1/2 ( Average thickness of H0 for ingot; H1 for slab thickness; The h2 for the thickness of the steel plate) 。 In addition all rolling method than composite rolling method can get more neat edge, steel plate not easily into the bucket ( As shown in figure 8 3 - 2) Cut, and thus reduce the loss. Also due to the rolling method than composite rolling method to reduce a steel time, and to improve yield. So the whole rolling method is often used to blooming billet as raw material of plate production. But due to the limitation of billet length specifications quantity, adjust the flexibility of small steel plate width. D Angle rolling - Longitudinal rolling method called Angle longitudinal axis is the rolled piece and roll axis at an Angle to roll for rolling method ( See 8 - 3 - 3) 。 It into Angle changes within the range of 150 ~ 450, each diagonal rolling after 1 ~ 2, or change to another diagonal rolling. Angle of rolled piece in rolling when every rolling line of rolled piece in the original width have been extended and make the width increases, at the same time rolled piece into a parallelogram. When rolled piece to the other diagonal rolling, rolling workpiece width continues to increase, and the rolled piece from parallelogram to the rectangle. Rolled piece after each rolling along the rolling width can be determined press type: advantage is can improve the conditions of nip Angle rolling, reduce the bit fashionable the enormous impact, and the Angle of the rolled piece and roll contact width is smaller than the cross rolling, thus reduce rolling pressure, so as to improve the strip shape, increased the production. To a narrow slab corner rolling method can prevent the rolled piece on the guide 'horizontal'. Angle rolling - Longitudinal rolling method because of the rolled piece on the longitudinal and transverse directions are deformation, thus can improve the anisotropy of rolled piece. Defect is need to dial the steel, so that rolling cycle extended, reduces the production, and into the Angle and shape of the steel plate is difficult to control, make cut loss increases, yield is reduced, the intensity of labor is big, complex operation, hard to automate. So the Angle rolling - Longitudinal rolling method only USES in ingot slaughter 3-roller mill as raw materials.