JPS6316801A - Rolling method for bar - Google Patents

Abstract

PURPOSE:To obtain a bar having excellent surface characteristics by executing one pass of rolling after shaping the free deformation surface of a material to be rolled of the previous pass rolling. CONSTITUTION:Recesses 3 and angle parts 4 of the free deformation surface of the material to be rolled which is rolled by oval caliber rolls 1-2 are shaped by sizing rollers 7 and are then rolled by round caliber rolls 1-3. Since the bite is smooth and the rolling reduction in the peripheral direction of the material is uniformized in the rolling with the round caliber rolls 1-3, the metal flow of the material surface is smooth and the rolling is executed without overlapping flaws. The surface flaws of the bar are, therefore, decreased, the fine adjustment of the rolls is decreased and the surface flaws of the wire are decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of rolling a material such as steel or non-ferrous metal to obtain a strip such as a square or round material with excellent surface properties.

(Prior art) When rolling billets or blooms (hereinafter referred to as raw materials) of steel or non-ferrous metals to produce strips such as square or round materials, grooved rolls are used in all passes as shown in Figure 3. 1 or, as shown in FIG. 4, a combination of a flannel roll 2 and a grooved roll 1 is used to reduce the cross section of the material to be rolled.

When rolling with grooved rolls, the optimum shape of the groove is determined by the cross-sectional shape and dimensions of the rolled material rolled in the previous pass and the cross-sectional shape and dimensions of the rolled material after the pass.

However, even if rolled with an optimally shaped groove roll, the shape of the rolled material will change if the composition or temperature of the material changes, or if the roll diameter or surface roughness inside the groove changes. Therefore, if this is further rolled, the following problems will occur.

In other words, if the cross-sectional shape of the material to be rolled before the relevant pass is not appropriate and the corner of the material to be rolled has a sharp point (hereinafter referred to as a corner) or if the free deformation surface has a recess, the shape of the material to be rolled after rolling Wrinkle defects may occur in the material, or scale may be caught between the hole mold and the rolled material, causing scale defects, which may cause defects in the finished product.

As a method to prevent wrinkles and fold-in defects caused by the corners of the rolled material before the pass, it is particularly important to round the corners using a roller guide on the entry side of the slotted roll. It is known from the publication No. 58-23503.

However, in this conventional method, a light reduction is applied from the same direction as the rolling direction of the rolling rolls before the pass, so the free deformation surface that did not come into contact with the rolling rolls before the pass is not shaped and is free from deformation. If the surface has a recessed portion, this may cause defects in the finished product.

(Problems to be Solved by the Invention) In the rolling process of special strip materials, recesses occur on the free deformation surface due to the characteristics of the rolled material and the relationship between the roll diameter and material method 1. There was a problem that this resulted in defects in the finished product.

For example, as shown in FIG.
If a concave portion 3 occurs on the free deformation surface of the rolled material rolled in step -2, the material to be rolled may be twisted by 90'' and the free deformation surface may be rolled by the round hole roll 1-3. , the concave portion 3 is not corrected and a folding flaw 5 occurs.Furthermore, the corner portion 4 of the material to be rolled by the oval hole type roll 1-2 becomes a wrinkle flaw 6.

The present invention prevents the occurrence of folding defects and wrinkle defects caused by concave portions and corners of the freely deformed surface of the rolled material rolled in the previous pass when the material is rolled into strips through multiple passes. to prevent
The purpose is to manufacture strips with excellent surface properties.

(Means/effects for solving the problems) The present invention is a method of rolling a material in multiple passes to form a strip, in which at least one pass of rolling is performed on the free deformation surface of the rolled material of the previous pass. It is characterized by being performed after shaping.

The materials targeted include billets and blooms of steel materials such as carbon steel, stainless steel, and high-alloy steel, as well as non-ferrous metals such as titanium and titanium alloys.

Rolling can be carried out by using grooved rolls for all buses as shown in Figure 3, by using a combination of flat rolls and grooved rolls as shown in Figure 4, or by using flat rolls for all buses. Both are eligible. Furthermore, the cross-sectional shape of the finished product is not particularly limited;
Both square and round timbers are eligible.

゛Hereinafter, the method of the present invention will be explained with reference to FIGS. 1 and 2.

In Figure 1, after rolling with oval hole type roll 1-2 of horizontal stand l' (H stand), sizing roller 7
Shape the free deformation surface with , then twist 900 degrees, ■1
An example of rolling with a round hole type roll 1-3 of a stand and an example of rolling with a round hole type roll 1-3 of a vertical stand (V stand) without twisting are shown.

The recesses 3 and corners 4 of the freely deformable surface of the rolled material rolled by the oval groove roll 1-2 are shaped by the sizing roller 7 and then rolled by the round groove roll 1-3, so that they are rounded. In rolling with the grooved rolls 1-3, the biting is smooth and the rolling reduction in the circumferential direction of the material is equalized, so the metal flow on the material surface is smooth and rolling can be performed without folding defects or wrinkling defects.

Figure 2 shows an example of rolling with the flat roll 2 of the H stand, shaping the free deformation surface with the sizing roller 7, then twisting 90'' and rolling with the flat roll 2 of the H stand, and an example of rolling with the flat roll 2 of the H stand. , (2) shows an example of rolling with flat rolls 2 of a stand.

In this example, as in the example shown in FIG. 1, the recesses 3 and corners 4 of the free deformation surface are shaped by the sizing roller 7, so that no flaws will occur during rolling by the flat roll 2 in the next pass. .

In addition, the shaping of the free deformation surface by the sizing roller 7 may be applied between grooved rolls other than those shown in Fig. 1, such as between flat rolls, between a flat roll and a grooved roll, or between a grooved roll and a flat roll. It may be applied in between.

When rolling is performed in multiple passes using a combination of various rolling rolls depending on the material and shape of the raw material and strip, one or more passes of rolling are used to shape the areas where defects are likely to occur. Just go.

As for the rolling method, in the case of a combination of flat rolls,
Not only tandem rolling but also reverse rolling may be used.

The sizing roller that shapes the freely deformable surface is preferably one whose roller spacing can be adjusted. Since a light reduction is sufficient for shaping, the rotation of the rollers may be non-driven and there is no particular need to drive them.

According to the method of the present invention, even if there is a dimensional difference in the material width between the free deformation surfaces of the rolled material before shaping due to the material composition, temperature, rolling conditions, etc.
As shown in the figure, since the material width is shaped to a constant dimension by the sizing roller 7, the fine adjustment of the roll gap between the rolling rolls after shaping can be reduced.

(Example) A 150 mmφ billet of stainless steel was tandem rolled on an H stand of box-oval-round groove rolls, and when rolling a 63 mmφ strip, the oval groove roll was used as shown in FIG. The surface flaws were determined between the case of shaping with a sizing roller and twisting by 90° with a twist guide (example of the present invention), and the case of twisting with a twist guide without shaping (conventional example). The occurrence situation was compared.

As a result, in the conventional example, folding flaws and wrinkle flaws with a depth of 0.3 mm were generated, whereas in the present invention, the depth was reduced to about 0.1 mm, and the frequency of occurrence was also reduced. Furthermore, when this was subsequently rolled into a wire rod of 5.51φ, the yield loss due to surface flaws was significantly reduced.

(Effects of the Invention) According to the method of the present invention, the surface flaws of the strip material are significantly reduced, the fine adjustment of the rolls is also reduced, and the surface flaws of the wire material obtained by subsequent rolling of this strip material are also significantly reduced.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory views showing the method of the present invention, FIGS. 3 and 4 are explanatory views showing an example of rolling roll rows, and FIG. 5 is an explanatory view showing an example of occurrence of flaws. 1 Niopal hole type roll 2: Flat roll 3; Concave portion 7; Sizing roll Agent Patent attorney Tatsuo Chanoki Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A method for rolling a strip into a strip by rolling a material in multiple passes, characterized in that at least one pass of rolling is performed after shaping the free deformation surface of the rolled material in the previous pass. .