JPS63140704A - Hot rough rolling method for steel bar and wire rod - Google Patents

Abstract

PURPOSE:To decrease the amt. of the folding defects to be generated in a rolled head part by subjecting a billet to hot rough rolling while the shear droop position thereof is directed upward. CONSTITUTION:The shear droop 3 generated at the time of cutting the billet 1 is positioned upward and the billet is subjected to the hot rough rolling at the time cutting the billet to a prescribed length and forming the same to a steel bar, wire rod, etc., by the hot rough rolling. The positioning of the shear droop 3 is executed by uniformizing the same in the specified direction at the time of charging the billet to a heating furnace or rolling the billet. The amt. of the folding defects to be generated at the rolling head part at the time of the rough rolling is decreased by this method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for hot rough rolling of steel bars and wire rods from billets produced by continuous casting or blooming.

[Conventional technology]

continuous! The billet produced by rolling or blooming is cut into a predetermined length using a No. I heating furnace or the like. In the past, rolling was carried out without taking into consideration the position of shear sag on the cut surface of the billet.

[Problem that the invention seeks to solve]

There were problems such as the shearing of the cut surface that occurred when the billet was cut, which promoted curling defects during rolling, leading to a decrease in yield.

[Means for solving problems]

As a result of various studies to solve the above problems, we found that the shear sag that occurs during billet cutting has a large effect on the occurrence of curling defects on the head of the product. During rolling, the position where the yarn sag occurs is controlled in an upward direction to perform hot rolling.

[For production]

In this invention, when a billet (1) produced by continuous casting or blooming is cut into a predetermined length, the cut surface (2)
A drizzle (3) occurs. This sharing sauce (3)
In addition, it was found that during hot rough rolling of a steel bar wire rod, the thickness (influenced) on the occurrence of fold-in flaws (X1), especially in the rolling part m, was found to be large.

For example, in this explanation, #1 to #8 in Figure 2
This is thought to be due to the fact that the lower part of the rolled material (billet) comes into contact with the exit trough or guide in the bus hole type, causing shear sag to flow backward (toward the main body of the rolled material).

Measures to prevent this phenomenon include the VL positioning of horizontal rollers, but this has not yet been completely resolved. Therefore, in the present invention, hot rough rolling is performed with the shear sag position (3) facing upward in order to reduce the curling defects. Rough rolling in the description of this invention refers to groove stands #1 to #8, which are not shown in FIG.

〔Example〕

An embodiment of this invention will be described below.

Table 1 shows the rolling conditions and rolling results.

The material used in this example is ordinary carbon steel, and the dimensions are 1
A billet with a square cross section of 80 mm was rolled into a product of 48 amφ according to the rolling bus schedule shown in FIG.

First, rolling was performed with the position of the shear sag (3) according to this invention method shown in Figures 1 (a) and 1 (b) facing upward ((a) the top and left, and (b) the top and right). As a comparative example, hot rough rolling was carried out with the position of the shear sag (3) facing downward (not shown in Figure 1 (C)) (Figure C: bottom and left, Figure 1: bottom and right). Rolling with the position of the shear sag (3) facing upward may be controlled by rough rolling, that is, from #1 to #8.

As is clear from Table 1, the shear droop (
When rolling is performed with the position of 3) facing upward,
The length of the curling flaw on the rolling head is 430mm to 550mm, while in the comparative example it is 660mm to 820mm, and in the case of the method of the present invention it is 200mm to 300mm long.
It was possible to reduce the length of the rolling-in flaw. The shears of the billet may be positioned in a certain direction when charging into a heating furnace or during rolling.

Margin Table 1 below [Effects of the Invention] As described above, according to the present invention, the position of the shear on the cut surface of the billet is managed, and rolling is performed with the position of the shear facing upward during rolling. It is possible to reduce the amount of curling defects.

[Brief explanation of the drawing]

Figures 1(A) and 1(B) are schematic explanatory diagrams showing an embodiment of the present invention, Figures 1(C) and 1(C) are schematic explanatory diagrams showing a comparative example, and Figure 2 is a schematic explanatory diagram showing an example of the present invention. FIG. 3 is a schematic explanatory diagram showing the bus schedule of the embodiment, and FIG. 3 is a schematic explanatory diagram showing the state of the cut surface of the billet. 1... Billet 2... Cut surface 3... Shear sag

Claims (1)

[Claims] When a billet manufactured by continuous casting or blooming rolling is cut into a predetermined length and subjected to hot rough rolling of a steel bar or wire rod, the shear portion that occurs when cutting the billet is positioned in an upward direction, A method for hot rough rolling of a steel bar wire rod, characterized by carrying out normal hot rough rolling.