JPS61286001A - Rolling method for steel rod and wire - Google Patents

Abstract

PURPOSE:To make possible stable size-free rolling by disposing box caliber rolls having projecting central parts to at least the foremost stage rolls of a rough rolling or intermediate rolling stage and disposing flat rolls to the other rolls. CONSTITUTION:A steel rod or wire is subjected to rough rolling or intermediate rolling in a tandem rolling mill train disposed alternately with driven horizontal rolls H and driven or non-driven vertical rolls V. The box caliber roll having the projecting central parts are disposed to the foremost stage rolls H and final stage rolls H of the rough rolling stage or intermediate rolling stage and the flat rolls are disposed for the other rolls. Then the section of a material to be rolled is maintained in a double-barrel shape and the high-draft rolling is made possible without the inclination of the material. The stable and highly efficient free-size rolling of the steel wire and rod is thus made possible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for rolling long steel (round bars, square bars, etc.) and wire rods, and in particular, a rolling method using driven horizontal rolls and driven or non-driven vertical rolls. The present invention relates to a size-free (groupless) rolling method using a tandem mill.

[Conventional technology]

Conventionally, as a method for rough rolling steel bars and wire rods, it has been common to use grooved rolls in which grooves (groups) are provided in the rolls. In recent years, a grooveless rolling method using flat rolls has been developed, for example, in Japanese Patent Publication No. 54-375, for the purpose of size-free rolling in which the same roll is used to roll various dimensions in the rough rolling stage or intermediate rolling stage.
This method is disclosed in Japanese Patent Application Laid-open No. 82, Japanese Patent Application Laid-Open No. 58-23502, Japanese Patent Application Laid-Open No. 58-68402, and the like. All of these methods regulate the aspect ratio (ratio of width to thickness) of the material from the viewpoint of elongation efficiency and stability, but the stability against collapse of the material is not necessarily good. Therefore, guides for guiding and restraining materials to prevent them from falling are important.
No. 6, @Kokai No. 58-6717, JP-A No. 58-3718
Although a guide for passing through the rolls has been proposed in the above publications, in reality, there are limits to the guidance and restraint provided by guides.

For example, the leading and trailing ends of the rolled material are unstable and difficult to guide. In addition, when the guide is tightly restrained to prevent the material from falling down, there is a risk that the guide may become jammed and cause flaws. Therefore, the guide is only an auxiliary means for guiding the material, and basically it is important to improve the stability of rolling itself.

When the thickness and width of the material are rolled alternately using flat rolls, the basic method for improving the stability of rolling is to roll the free end of the material into a concave shape, as shown in Figure 7(a). The cross section has a so-called double barrel shape. This improves the stability when the concave free surface is subsequently rolled down with a flat roll. Such double-barrel formation of the free end face can be obtained by light reduction rolling using small diameter rolls, but rolling efficiency decreases. Generally, as shown in Figure 7(b), the free end surface has a convex cross section, so-called a single barrel shape, and then this convex cross section is rolled down with a flat roll, so the stability during rolling is extremely high. Deteriorate. Therefore, if we try to create a double barrel by reducing the rolling reduction of the horizontal roll at the front stage of the tandem, we can simplify the rolling stand by omitting the drive system and improve the workability of rearranging the rolls by moving the next vertical roll. In the case of no drive, there was insufficient force to push the material into the vertical rolls, resulting in poor biting.

[Problem that the invention seeks to solve]

In the conventional groupless rolling method using flat rolls as described above, the stability against falling of the material is not necessarily good, so even if guides are used for guidance and restraint, there are limitations, and guide packing and There was a risk that pear defects would occur. Furthermore, if an attempt was made to obtain a double barrel shape by lightly reducing the initial rolling, the pushing force of the next vertical roll could not be ensured, resulting in problems such as insufficient biting.

This invention was made in order to solve the problems of the conventional method as described above, and it improves the stability of rolling against material collapse without hindering the size-free design, and also improves the stability of rolling with heavy reduction. The purpose is to make it possible.

[Means for solving problems]

The rough rolling method for long steel and wire rods according to the present invention is characterized in that driven horizontal rolls and driven or non-driven vertical rolls are arranged alternately, and in a tandem rough rolling mill row or a tandem intermediate rolling mill row, at least the roll of the foremost rolling mill is used. A box 120-roll with a convex center is arranged in the rolling mill, and flat rolls are arranged in the other rolls of the rolling mill.

[Effect]

In the method for rough rolling steel bars and wire rods according to the present invention, a box hole type roll having a convex center portion is disposed at least at the frontmost roll in the rough rolling stage or intermediate rolling stage.
The cross section of the rolled material is shaped like a double barrel to prevent the material from collapsing, enabling strong reduction rolling and securing the pushing force to the next vertical roll, allowing stable size-free rolling.

[Embodiments of the invention]

FIG. 1 is a schematic diagram of an embodiment of a tandem rough rolling mill row and a tandem intermediate rolling mill row to which the rolling method of the present invention is applied;
After passing through both rows of rolling mills, it is finished into products by a finishing machine row (not shown).

In the figure, H is a driven horizontal roll, ■ is a driven or non-driven vertical roll, and the first roll H and the last roll ■ in the rough rolling mill row have a convex central part as shown in Figure 6. A box-hole type roll is arranged, and the other horizontal rolls H and vertical rolls V are flat rolls.

When all the rolls are flat rolls, the free end surface of the material tends to have a single barrel shape with a convex cross section, and especially when heavy reduction rolling is performed, the single barrel shape appears largely and the rolling becomes unstable and causes the material to collapse. Once the material collapses, it is impossible to correct it even if a guide is used with a flat roll, as shown in FIG. 2(b). For this purpose, a box-hole type roll with a convex central part is arranged on the first stand of the rough rolling mill row, and the rolling surface of the material is made concave as shown in Figure 2 (a). V rolling gives the free end surface of the material a double barrel shape. In this way, even when rolling a material with a single double barrel shape using the horizontal rolls H, there is a large metal flow in the width direction at the corner of the material, and the double barrel shape is repeated in each rolling stage. Improved stability.

When rolling a square material with side dimensions A, this box hole type roll is formed with the dimensional relationship shown in Fig. 6, and by disposing it at the last stage roll of the rough rolling mill row,
It is possible to promote double-barrel formation of the material in subsequent intermediate rolling mill rows and greatly improve rolling stability.

In this case, since size-free rolling is performed, the number of box holes is not one as shown in FIG. 4 (IL), but as shown in FIG.
As shown in b), if a plurality of box holes are formed and the rolls are shifted in the axial direction according to the rolling size, size-free rolling becomes possible.

Incidentally, a plurality of box hole shapes are similarly formed on the first stage rolling roll.

Due to the effect of material restraint by this box hole, the fifth
As shown in the figure, when rolling is performed without driving the vertical rolls V, which have a large force in the rolling direction, the pushing force to the vertical keel V and the pulling force from the vertical rolls can be increased, and the rolling amount of the straight rolls can also be increased. It becomes possible to do so. Figure 6(a) shows the change in the material cross section when these box-hole type rolls are placed in the first and last stands of the rough rolling row.
As shown in FIG. 6, the double barrel shape is maintained even in the intermediate rolling row, compared to FIG. 6(b) using only the conventional flat rolls. Note that specific examples of the arrangement of rolling mills according to the present invention are shown in Table 1.

As shown in this table, the rolling reduction amount Δh in the row of rough rolling mills is
It is possible to take a sufficiently large diameter from the most forward-stage tube-rule (first pass), and it becomes possible to improve rolling efficiency.

BT: billet material, H: horizontal roll, v: vertical roll, R: roll radius, hH: exit side thickness, hv: exit side width, Δh
: Reduction amount [Effect of the invention] As explained above, this invention is a size-free rolling method using a tandem rolling mill with driven horizontal rolls and driven or non-driven vertical rolls, in which box-hole type rolls are partially applied. The free end surface of the material to be rolled has a double barrel shape, so that the material does not fall down, and the amount of reduction with the flat rolls can be increased, allowing stable and highly efficient rolling.

Further, the guide may be used as an auxiliary material, eliminating the need for a high-strength guide, improving dimensional accuracy, and preventing the occurrence of guide scratches. Furthermore, in the case of rolling in which the vertical rolls are not driven, the pushing force to the vertical rolls and the pulling force from the vertical rolls can be ensured, and effects such as improved pushing and pulling limits can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the roll arrangement of rough rolling and intermediate rolling rows of long steel and wire rods according to an embodiment of the present invention, and FIG.
) , (b)) t 11-7' Luparel shape An explanatory diagram of the generation mechanism of the single parel shape, Figure 3 is an explanatory diagram showing an example of box hole dimensions, Figure 4 (a),
(b) is a schematic diagram showing an example of arrangement of box-hole type rolls, Figure 5 is a comparison diagram of force generation in the rolling direction, Figure 6 (a),
(b) is a comparison diagram of material cross-sectional changes in the rough rolling row and the intermediate rolling row, and FIG. 7 is an explanatory diagram of stability due to the double barrel shape and single barrel shape of the material cross section. In the figure, H is a horizontal roll and ■ is a vertical roll. Agent: Patent Attorney Tadashi Sato Figure 3 Figure 4

Claims (1)

[Claims] In tandem rough rolling mill rows or tandem intermediate rolling mill rows in which driven horizontal rolls and driven or non-driven vertical rolls are arranged alternately, at least the roll of the foremost rolling mill has a box-hole horizontal roll with a convex central portion. A method for rolling steel bars and wire rods, characterized in that the rolls of the other rolling mills are flat rolls.