SU1731533A1 - Method of rolling bimetallic material - Google Patents

Abstract

Use: at the plants of ferrous and non-ferrous metallurgy, producing bime-tall steel. A bimetal is rolled with different layer properties in the rolls with misalignment of circumferential speeds, with a component with high deformation resistance located on the side of the roll having a lower circumferential speed. During rolling, the strip at the inlet and at the exit from the deformation zone is directed at an angle to the horizontal plane from the side of the roll having a large circumferential speed. The angle between the stripe and the horizontal should not be less than the angle of capture. 1 ill., 1 tab.

Description

The invention relates to the field of metal forming, namely the production of bimetals, and can be used in the factories of ferrous and nonferrous metallurgy, producing bimetallic products.

A known method of manufacturing a bimetal, predominantly steel-copper, involves rolling an explosion-welded package in rolls of the same diameter with a mismatch of angular velocities. The ratio of the angular velocity of the roll in contact with the layer of steel to the angular velocity of the roll in contact with the copper layer is 0.9-0.95. This method reduces the irregularity of the layer-by-layer deformation of the bimetal, and, as a result, improves its quality.

However, the narrow range of regulated roll skidding values does not allow this method to be used for other possible combinations.

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components with different geometrical and mechanical characteristics. In addition, when rolling with a deformation of less than 5% at the specified ratio of roll speeds (0.9-0.95), the roll slipping in contact with the copper layer relative to the metal surface occurs, which adversely affects the surface quality of the bimetal.

The closest to the proposed technical solution is the method of clad strips, including the regulation of the speed of rotation of the upper and lower rolls depending on the ratio of the thicknesses of the original strip blanks. The method allows to achieve the required ratio of the thicknesses of the components of the bimetallic strip.

However, in the case when the required stretching of the strips is small, and the difference in the geometric and mechanical characteristics of the components is significant, the method may not

4 W

BUT

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to give the desired result, since the magnitude of misalignment of the speeds of the rolls cannot exceed the stretching, i.e.

,

VB2

where vBi, vB2 are, respectively, the circumferential speeds of the roll rotating faster (leading) and the roll rotating slower (driven);

A - stretching strip.

In case vBi / vB2 A, the drive roll slips against the surface of the strip, which leads to a violation of the stability of the rolling process. A further increase in the mismatch between the roll speeds due to slipping does not affect the thickness ratio. Thus, when implementing this method, it may turn out that, by changing the mismatch of the roll speeds, it is not possible to achieve the required ratio of the thickness of the components.

The purpose of the invention is to improve the quality of the bimetal by changing the geometry of the strip and the adhesion of the layers.

The goal is achieved by the method of rolling a bimetal with different properties of the layers in the rolls with a mismatch of circumferential speeds, and a component with high resistance to deformation is placed on the side of the roll having a lower peripheral speed, the strip at the inlet and outlet of the deformation zone is directed at an angle to the horizontal plane from the side of the roll, which has a greater peripheral speed, while the angle is taken to be not less than the angle of capture.

The drawing shows a scheme for implementing the method.

The poor quality of the geometry, characterized by the residual bending of the strip, and the poor quality of the adhesion of the layers, leading to delamination of the bimetal during its further processing, are a consequence of the unequal conditions of deformation of the bimetal components due to the difference in their geometric and mechanical (strength) characteristics. The deformation conditions of the different properties of the components can be equalized by using the speed asymmetry of the rolling process. From the practice of rolling production it is known that the deformation of the metal from the driven roll is greater than from the lead, and the greater the mismatch of the roll speeds, the more noticeable this effect, However, with a significant difference

The mechanical and geometrical characteristics of the components of a bimetal may be the case that the use of this technique may be insufficient for

leveling the deformation conditions of the components.

With the passage of a bimetallic strip of rolls along a U-shaped trajectory, as shown in the diagram, the condition of deformation

0 components is aligned. The latter is explained by the fact that when a strip bends, additional stresses arise in it, namely compressive stress (-) for the inner layers and tension of the same 5 (+) for the outer layers. In this case, the presence of compressive stresses prevents deformation, and the presence of tensile stresses contributes to the deformation. Consequently, bending the strip in such a way that

The component with less resistance to deformation is located inside the arc of bending, preventing its deformation, at the same time contributing to the deformation of the component with greater resistance to deformation.

5 Therefore, conditions are created for leveling the layer-by-layer deformation of the components.

The proposed effect has the maximum effect if the angle between

0, the strip and axis of rolling will not be less than the angle between the axis of rolling and the tangent to the roll, carried out at the point of entry of the strip to the deformation zone, i.e. grip angle.

Increasing the angle between the strip and the axis

5 rolling over the capture angle does not have a positive effect on the alignment of layer-by-layer deformation, but reducing it leads to an increase in the non-uniformity of the layer-by-layer deformation of the components of the bimetal.

The method is carried out as follows.

In the method of rolling a bimetal with different properties of the layers in the rolls with the settlement of peripheral speeds, the component with high deformation resistance is placed on the side of the roll having a lower peripheral speed, a strip at the entrance and exit of the hearth

0, the deformations are directed at an angle to the horizontal plane from the side of the roll, which has a greater circumferential speed, and the angle is taken to be not less than the capture angle.

5 PRI me R. Annealed bimetallic tape copper + steel 12X18H9 was used as the starting material. The thickness of the copper layer is 0.2 mm, the thickness of the steel layer is O. mm. Rolling was carried out on the wall duo with a diameter of

rolls 200 mm. The tape was rolled from a thickness of 0.8 mm to a thickness of 0.6 mm, while the stretching was A 1.33. In order to maximize the use of speed asymmetry, the misalignment of the roll speeds in all cases was 1.3.

Rolling was carried out according to the method of the prototype and the proposed method. In this case, the recommended bending angle of the strip

A rarccos () 2.56 °.

Due to the design of the mill, the bending angle of the strip is 10 °.

The quality of the adhesion of the layers was evaluated by the method of repeated bending of the tape by 180 ° according to GOST until the appearance of delamination or fracture. In the initial state, the tape held 4 kinks without stratification.

Comparative results of rolling are shown in the table.

From the analysis of the results obtained, it is obvious that the proposed method improves the quality of the bimetal by increasing the quality of the adhesion of the layers and by reducing the bending of the strip at the exit of the rolls.

Claims (1)

Invention Formula The method of rolling a bimetal with different properties of the layers in the shafts with the mismatch of peripheral speeds, and a layer with high resistance to deformation is placed on the side of the roll having lower circumferential speed, characterized in that, in order to improve the quality of the bimetal by changing the geometry of the strip and the cohesion of the layers, the strip, at the inlet and at the outlet of the deformation zone they are directed at an angle to the horizontal plane from the side of the roll, which has a greater circumferential speed, and the angle is taken to be not less than the capture angle. Component with - less dedhernotia resistance Component q big resist deformations