JPS58188502A - Rolling method of round billet - Google Patents

Abstract

PURPOSE:To roll a round billet with a less number of steps and to roll the same efficiently to a round billet of the further smaller diameter by rolling the flat semicircular billet obtained by rolling a round billet in the direction at a right angle to the axis thereof with round caliber rolls by changing the rolling-down direction thereof by 90 deg.. CONSTITUTION:A round billet 1 is rolled with, for example, flat rolls 2, 2, etc. to obtain a flat semicircular billet 3. The billet 3 is rolled by round caliber rolls 7, 7 by changing the rolling-down direction thereof by about 90 deg.. While the bulging in the short diameter direction is regulated by the rolls 7, 7, the billet 3 is reduced in the direction of long diameter, whereby a round billet 8 of a prescribed shape is obtained. As a result, the round billet is rolled with a less number of steps (two passes in the least case) and such inconvenience in operation as the falling-down of the material under rolling is obviated. The size of the round- shaped ingot is thus changed extremely efficiently and easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rolling a round billet into a smaller diameter round billet.

Continuous casting requires a wide variety of dimensions depending on the dimensions of the rolled product. In order to meet this requirement, slabs of various sizes have been manufactured in the past using many types of molds, but this method requires time and effort to change molds, and cannot necessarily be said to be a rational method. Therefore, in recent years, the dimensions of the cast slab have been changed by rolling the cast slab. This method uses the high temperature of the cast slab to directly roll it, so there is no need for heating, and it is attracting a lot of attention. In the case of square slabs, rolling is easy and practical use is progressing, but in the case of original slabs, it is difficult to hold the slabs, so practical use of square slabs has not progressed. At present, the methods considered for rolling the original mirror piece are the methods shown in Fig. 1G) to 1.

First, the round billet shown in Figure 1(a), which is the prototype slab (
For example, 1,000 rolls (2) (1) as shown in Figure 1 et al.
2) etc. to roll. Next, the flat half-round billet (3) shown in FIG. 1(c) obtained by this rolling is rolled with square hole type rolls (4) (4) as shown in FIG. A square billet (5) as shown in Figure (e) is made. The purpose of turning the round billet (1) into a square billet (5) is to make it easier to obtain an octagonal billet shape before finishing. Once a square billet (5) of predetermined dimensions is obtained, this square billet (5) is then rolled into a suitable grooved roll (
(not shown) to form an angular billet (6) as shown in Figure 1(f), and then further rolled with round hole type rolls (7) (7) as shown in Figure 1(Ig). first
It is made into a round billet (8) as shown in Fig. 1h).

In the case of this method, it is impossible to convert the round billet (1) into a perfect square billet (5) in two passes; it is generally said that four passes are required.
), and 1 pass is required to convert the octagonal billet (6) into the round billet (8), so a total of 7 passes are required. Nevertheless, the diameter ratio of the round billet (8) to the round billet (1) is about 75% because the diagonal dimension of the square billet (5) must be less than or equal to the outer diameter dimension of the round billet (1). It cannot be made larger. In other words, this method requires a lot of man-hours and lacks versatility.
A square hole roll (4) is used to turn 3) into a square billet (5).
(4), the material tends to fall over within the roll (4) (see Figure 1 1d)).

This makes rolling into a square billet (5), which is otherwise time-consuming, even more complicated.

An object of the present invention is to solve these problems and provide a method that can efficiently roll a round billet into a smaller-diameter round billet with fewer man-hours.

By the way, as mentioned above, the reason why the round billet (1) is once rolled into a square billet (5) in the conventional method is to make it easier to obtain an octagonal shape before finishing. However, round billet (1) is replaced by round billet (8
) It is unreasonable to temporarily form a square billet (5) in the middle of rolling into a square billet (5). The present inventors believed that in order to efficiently roll a round billet, it would be a good idea to preserve the original shape of the round billet (1) as much as possible, and based on this idea, various rolling methods were tried. As a result, Figure 2 (
As shown in a) to (e), the flat half-round billet (3) obtained by rolling with flat rolls (2) (2) etc. is directly rolled with round hole type rolls (7) <7) to form a round billet. Billet (
8), it not only saves the trouble of once rolling into a square billet (5) (see Figure 1), but also significantly reduces the number of man-hours. It has been found that the flat half-round billet (3) is effectively held within the rolls (7) (7), preventing its overturning and resulting in extremely efficient rolling as a whole.

The present invention has been made based on the above knowledge, and after rolling a round billet (1) in a direction perpendicular to the billet axis to form a flat half-round billet (3), the flat half-round billet (3) is rolled. The rolling direction was changed by about 98 degrees and a round hole type roll (7
) (7) to form a round billet (8) having a smaller diameter than the round billet (1).

Hereinafter, the method of the present invention will be explained in more detail with reference to FIG. 2 mentioned above.

First, as shown in Figures 2, et al.) to (c), a round billet (
11 is rolled using, for example, a flat roll (2M2) or the like to form a flat semicircular billet (3). In this process, the round billet ( ) is simply rolled in a direction perpendicular to the billet axis, so there is no need for the material to fall over, the amount of rolling can be kept small, and rolling can be completed in one pass.

However, this does not prevent the use of two or more passes if necessary.

The amount of rolling reduction per pass in this step is desirably within the range of 30 to 1001Q, because if it is too small, the rolling efficiency will decrease, and if it is too large, it will cause twisting and bending of the material.

Once the flat semi-round billet (3) is obtained, the next step is as shown in Figure 2 (d
) to (υ), the flat semi-round billet (illustration) is rolled by round hole type rolls (7) (7) with the rolling direction changed by about 90 degrees.By this rolling, the flat semi-round billet (3)
u, round hole type rolls (7) (7) reduce the bulge in the short axis direction while reducing in the long axis direction to form a round billet (8) of a predetermined shape, and furthermore, the round billet (L) prevents it from falling during rolling. This is reliably prevented by the roll holes of the mold rolls (7) (7).

It goes without saying that this step may also be based on one pass, or may be two or more passes. If this process is completed in one pass, the total number of passes is 2 and 7, and even if this process requires 2 passes, the total number of passes is only a small number.

The rolling reduction value per pass in this step is preferably within the range of 30 to 100 tWtQ, because if it is too small, the rolling efficiency will decrease, and if it is too large, it will cause bending and twisting of the material.

The roll hole type of the round hole type roll (7) (7) is
Round billet to be rolled if finished with a pass (8)
If this process requires two passes or more, the shape should be determined according to the shape of the flat half-round billet (3) and the one-valve billet (8).

As an example, a round billet made of carbon steel with a diameter of 282 mm was rolled by the hands shown in Fig. 2 G) to (→) to form a round billet (8) with a diameter of 216 + tm. Number of passes Rolling from a round billet (1) to a flat half-round billet (3) was 1, and rolling from a flat half-round billet (3) to a round billet (8) was 2. Figure 3 (a
) to (d).

Round billet (1) of round billet (8) in this example
) is approximately 90%, which is undeniably larger than that in the conventional method shown in FIG. 1 (approximately 75 inches). However, considering that conventional methods cannot produce more than 75 inches, this 90 inches is extremely significant. Moreover, whereas the conventional method requires 7 passes,
Considering that the method of the present invention can finish rolling in 2 to 3 passes as seen in the above examples, and that there is no material falling during rolling, the method of the present invention has many advantages.

In addition, as another example, a round slab made of carbon steel with a diameter of 2828 mm was rolled in the same manner as described above, and the diameter was reduced to 253 mm.
Although the Kakunomaru billet was obtained, the number of passes was only two, and there was no material falling over.

As is clear from the above description, the method of the present invention can roll a round billet into a smaller diameter round billet with fewer man-hours (two passes in the least), and there is no operational inconvenience such as falling of the material during rolling. Therefore, it is highly effective in enabling extremely efficient work and making it easy to change the dimensions of round slabs.

[Brief explanation of drawings]

FIGS. 1(a) to (h) are schematic diagrams illustrating the conventional round billet rolling method step by step, and FIGS. 2(a) to (e) are schematic diagrams illustrating the round billet rolling method of the present invention. Figure 3(a)~
(d) is a dimensional diagram showing changes in material shape in an example of the present invention. In the figure, 1: round billet before rolling, 2: flat roll, 3: flat half-round billet% 4: square hole roll, 5: square billet,
6: Hexagonal billet, 7: Round hole roll, 8: Round billet after rolling.

Claims (1)

[Claims] It is characterized by rolling a round billet while rolling it in a direction perpendicular to the billet axis to form a flat half-round billet, and then changing the rolling direction of the flat half-round billet by about 90 degrees and rolling it with a round hole type roll. Round billet rolling method.