JPS6326202A - Hot rolling method for channel steel - Google Patents

Abstract

PURPOSE:To form a flawless channel steel and to facilitate the cutting and repairing of a rolling roll by rolling a material to the rolling completion sectional shape with which the flanges are perpendicular to the web and a recess is formed in the longitudinal direction in the transverse central part of the web, then forming only the web flat. CONSTITUTION:The material 2 with which the rolling in the final stand of a rolling mill is completed is rolled to 90 deg. angle between the flanges 2b and the web 2a and to the wall thickness equal to the finish size of the final product. The flange 2b, 2b are inclined at a large angle toward the outside by the recess 8 formed longitudinally in the transverse central part of the web 2a. The difference in the circumferential speed of the rolling roll in the contact part of the rolling roll in the part near the boundary between the top end of the flange 2b and the web 2a is, therefore, smaller than with the material having the smaller inclination of the flanges and the surface flaws of the material are extremely few at the time of rolling by the final stand. The smaller quantity of cut of the caliber is necessitated and the contact length between the rolling roll and the material is short to obviate the generation of flaws in the flanges 3b, 3b at the time of repairing the rolling roll having the worn caliber by cutting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for hot rolling channel steel.

[Prior art and its problems]

In order to manufacture channel steel by hot rolling, conventionally, a billet having a rectangular cross-sectional shape is uniformly heated to a predetermined temperature in a Th heating furnace, and then passed through a rolling mill consisting of multiple stands to form a groove shape. Roll to Figure 4 (A) - ('J
) is an explanatory diagram showing the rolled shape. As shown in FIG. 4, the billet 1 gradually becomes an M-shaped material 2 as the rolling progresses, and at the final stand, the web 2a is flat, the flange 2b is at an angle to the web 2a, and The steel is rolled into a slightly inclined shape that is close to vertical, and is rolled into a channel steel 3 as shown in FIG.

However, the conventional method of rolling channel steel mentioned above has
There are the following problems.

[11 As can be seen from FIG. 4, in the final stand, the flange 3b of the channel steel 3 is rolled at right angles to the web 3a and into a slightly inclined shape close to perpendicular. As a result, at the contact portion with the rolling roll, which is close to the boundary between the tip of the flange 3b of the channel steel 3 and the web 3a,
Since there is a large difference in the circumferential speed of the rolling rolls, flaws are likely to occur on the surface of the channel steel 3.

(2) Flange 3b of channel steel 3 in the final stand
The angle between the flange 3 and the web 3a is a right angle, and the flange 3
b is extremely close to vertical. As a result, when the force IJ//- is used to cut and restore a worn rolling roll, the amount of cutting by the caliber is large and the base unit of the roll becomes high.

(3) As described above, since the flange 3b of the channel steel 3 in the final stand is nearly vertical, the contact length between the rolling roll and the material becomes long, and as a result, flaws are likely to occur in the flange 3b.

[41 If the material is alloy steel such as stainless steel,
The problem of fil~(3) mentioned above becomes even more noticeable.

[Purpose of the invention]

Therefore, an object of the present invention is to solve the above-mentioned problems, to prevent the occurrence of defects in the product, and to reduce the amount of cutting force IJ / The object of the present invention is to provide a rolling method.

[Summary of the invention]

The present invention provides a hot rolling method for channel steel in which a billet heated to a predetermined temperature is passed through a rolling mill consisting of a plurality of stands to be rolled into a channel shape, and the rolled shape in the final stand of the rolling mill is , a cross section in which the angle between the flange and the web is 90 degrees, the flanges are inclined toward the outside at a predetermined angle, and a recess is formed in the widthwise center of the web in its length direction. shape and absence,
Next, the material rolled into the above-mentioned shape can be formed by a forming machine consisting of a horizontal upper roll and a horizontal lower roll so that only the web is flat in the width direction without any rolled metal body. It has characteristics.

[Structure of the invention]

Next, the present invention will be explained with reference to the drawings.

In the method of this invention as well, a billet having a rectangular cross-sectional shape is uniformly heated to a predetermined temperature in a heating furnace, and then passed through a rolling mill consisting of a plurality of stands to successively form a groove shape as shown in FIG. The same is true for rolling.

Figure 1 shows the force IJ of the final stand in the method of this invention.
It is bar-shaped. In the method of the present invention, the final stand of the rolling mill does not roll the product into a perfect groove shape as shown in FIG. 4Q)). That is, as shown in FIG. 1, when the material 2 is completely rolled in the final stand, the angle between the flange 2b and the web 2a is 90 degrees;
Flange 2b.

2b are inclined toward the outside at a predetermined angle to each other;
In order to incline the flanges 2b, 2b in this manner, the web 2a has a substantially M-shaped cross section with a recess 8 formed in the length direction at the center in the width direction. Note that the wall thicknesses of the web 2a and the flanges 2b, 2b are the finished dimensions of the final product.

FIG. 3 is a layout diagram showing a part of rolling equipment for carrying out the method of the present invention. In the drawing, 4 is the last stand, 5 is the stand one step before the last stand 4, and the material moves in the direction of the arrow. final stand 4
The material 2 rolled into the shape described above is then molded in a molding machine 6.

The molding machine 6 consists of an upper roll 7a and a lower roll 7b,
The material 2 is formed so that only the web 2a, in which the recess 8 is formed at the center in the width direction, becomes flat without being rolled down. FIG. 2 is an explanatory diagram showing the molding state by the molding machine 6. As shown in FIG. 2, the web 2a is made flat by the upper roll 7a and the lower roll 7b, and thus the flanges 2b, 2b are erected vertically, forming a flat web 3a and vertical flanges 3b, 3b. A channel steel 3 consisting of the following is manufactured.

The length of the upper roll 7a in contact with the upper surface of the web 3a is on the width plate of the lower roll 7b, and is preferably on the width plate of the lower roll 7b.
Within the width excluding both edges.

This is because the bases of the flanges 3b, 3b, which are the contact points between the web 3a and the flanges 3b, 3b, are thick.

It is necessary that the upper roll 7a is in contact with the base. However, both edges are completely web 3ak
When the web 2a is covered and is in contact with the upper roll 7a, the material 2 with the recess 8 formed in the center of the web 2a is covered with the upper roll 7a.
When the web 2a is caught between the lower rolls 7b, both ends of the web 2a come into contact with the upper roll 7a. As a result, a shape defect occurs at both ends of the web of the product due to the impression of the upper roll 7a, and the upper roll 7a also suffers from abrasion, resulting in an increase in power costs. Therefore, both left and right ends of the upper roll 7a need to be tapered to have a diameter of /JX compared to the center part.

In this invention, the material 2 that has been rolled by the final stand 4 of the rolling mill is rolled so that the angle between the flange 2b and the web 2a is 90 degrees, and the wall thickness is the finished dimension of the final product. The flanges 2b, 2b are not vertical but are inclined outwardly at a large angle. Therefore, during rolling by the final stand 4, the difference in circumferential speed of the rolls at the contact area of the rolls near the boundary between the tip of the flange 2b and the web 2a is greater than that of the flange with a smaller inclination. Since there are very few surface defects on the material, when cutting and repairing a worn rolling roll with a caliber, only a small amount of cutting force is required, and the contact length between the rolling roll and the material is short. Therefore, no flaws will occur on the flange.

In order to exhibit the above-mentioned effect, the flange inclination angle of the material rolled in the final stand 4 is set to the distance NIA between the tips of the flanges 2b, 2b, as shown in FIG.
When expressing the straight line distance between both ends of the web 2a, 10 to 3
It is preferable to set it to 0%.

In the present invention, rolling of the channel steel is not limited to rolling with the flanges facing downward, but also includes rolling with the flanges facing upward.

In this case, due to the recess formed in the widthwise central part of the web in its length direction, the material can be approximately W until the final stand.
It will be rolled into a shape. At this time, the shapes, functions, features, etc. of the upper roll and lower roll are upside down from those described above.

〔Effect of the invention〕

As described above, according to the present invention, the difference in circumferential speed of the rolling rolls at the contact portion between the material and the rolling rolls in the final stand is small, and the contact length between the rolling rolls and the material is short. Therefore, it is possible to manufacture channel steel of excellent quality without defects, and when repairing worn rolling rolls by cutting, the amount of cutting by the caliber is small, so the roll consumption rate is reduced. Many industrially valuable effects are brought about, such as the ability to reduce

[Brief explanation of drawings]

Figure 1 shows the force IJ of the final stand in the method of this invention.
Figure 2 is a diagram showing the forming state in the rolling machine in the method of the present invention, and Figure 3 is a layout diagram showing a part of the rolling equipment for carrying out the method of the present invention. , FIG. 4 is an explanatory diagram showing a conventional rolled shape. In the drawings, 1... billet, 2... material, 2a...
・Web, 2b...flange, 3...channel steel, 3a...web, 3b...flange, 4...last stand, 5...last stand, one stand before the other , 6... Molding machine,
7a...Top roll, 7b...Bottom roll,
8...dent.

Claims (2)

[Claims] (1) In a hot rolling method for channel steel in which a billet heated to a predetermined temperature is passed through a rolling mill consisting of a plurality of stands and rolled into a channel shape, the rolled shape at the final stand of the rolling mill is: The angle between the flange and the web is 90 degrees, and
The flanges are inclined outward from each other at a predetermined angle, and the web has a cross-sectional shape in which a recess is formed in the widthwise center of the web in the longitudinal direction.Then, the material rolled into the above-mentioned shape is horizontally rolled. 1. A method for hot rolling channel steel, the method comprising forming only the web so that it is flat in the width direction without rolling down using a forming machine comprising a horizontal upper roll and a horizontal lower roll. (2) When the inclination angle of the flange is expressed as a ratio of the difference between the distance between the tips of the flange and the straight line distance between both ends of the web, the ratio is 10 to 30%. A method for hot rolling channel steel according to claim (1), characterized in that: