JPS62144801A - Hot rolling method for round section continuously cast ingot subjected to inline indentation cutting - Google Patents

Abstract

PURPOSE:To improve the yield of a product by subjecting a steel ingot to indentation working with upper and lower tools an to shearing with divided tools then to the biting for the 1st pass of a rough hot rolling mill in such a manner that the sharing direction intersects orthogonally with a roll surface. CONSTITUTION:The round section continuously cast ingot is subjected to the indentation working by the upper and lower tools b1, b2 and c1, c2 having a bisected and joined V sectional shape, then to shearing by a pair of the divided tools b1, c1 of the upper and lower tools in succession thereof in the inline cutting of said ingot. The indentation shearing direction in this stage is made parallel with each other at both end faces of the cut ingot; in addition, the ingot is bitten with the tools in such a manner that the indentation shearing direction of the continuously cast ingot is inclined about 45 deg. with the perpendicular direction, i.e., the shearing direction intersects orthogonally with the roll surface in the 1st pass of a square shaped caliber rolling train for hot rolling. The region where the surface flaws of the product are generated is decreased and the yield of the product is improved by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for hot rolling cut continuous cast pieces obtained by in-line push cutting of round cross-section continuous cast pieces. Conventionally, in many cases, a gas cutting method has been used to cut slabs in-line to produce rolled wire rod materials. However, the gas cutting method suffers from erosion of the material that occurs during cutting, which greatly reduces the overall yield.

Particularly in the case of high-grade steel materials such as stainless steel, it is necessary to minimize the material loss associated with cutting continuous slabs, and the gas cutting method has problems during cutting.

If in-line cutting of round-section continuous slabs is sheared using a press machine instead of using the gas cutting method, material erosion will not occur and it seems to be advantageous in terms of yield, but the normal press cutting method Since the load required to press-cut a continuous slab with a large cross section is extremely large, it is necessary to install large-capacity press equipment. Moreover, flow deformation of the material occurs near the cut surface, causing the cut shape to deviate from a perfect circle and causing cracks to occur on the cut surface.
These abnormal shapes are not corrected in the subsequent rolling and the influence remains, making it difficult to maintain good surface quality of the final rolled product, which may even result in a reduction in the overall yield.

On the other hand, in-line cutting by the indentation shearing method, as shown in Figure 1 (a) and (b) ρ, uses press equipment to combine the upstream and downstream halves of the slab [a]. Upper tool (bl) (b2) and lower tool (cl) (c
2) Indentation processing is performed using the above tools, followed by shearing using a pair of divided pieces (bl) and (c2) of the upper and lower tools. The small amount of pressure reduces the required press load throughout the process and there is no material loss during cutting.

(Problems to be Solved by the Invention) Many of the round cross-section continuous slabs of rolled wire rods made of ordinary steel and high-grade steel require skin removal on the surface of the cut continuous slab before hot rolling. Therefore, in addition to the normal skin cutting process using a rotary lathe, the indentation-sheared slab requires a process of cleaning the slab surface at the indentation part using a V-shaped tool, which reduces the effect of reducing material loss during cutting. be done.

The present invention aims to provide a solution to the above-mentioned problems of the prior art.

(Means, effects, and embodiments for solving the problems) In order to achieve the above-mentioned object, the present invention utilizes the deformation characteristics at the end of a round-section material during rolling, and To ensure the quality of the surface of a rolled product even without performing maintenance on one surface.

It was discovered that the deformation characteristics during hot rolling of round cross-section materials have the following characteristics.

(4) The position of the surface flaw after rolling at the chamfered end of a round section material (2i (the length from the material edge to the position where the surface flaw occurs) is determined by the direction of biting into the roll in the first rolling pass. Changes greatly.

03) In the first pass, the surface flaw position can be minimized by making the chamfering direction perpendicular to the roll surface.

(In the O-in-line indentation shearing method, the chamfering effect of the end face obtained by indentation processing using a shaped tool can be utilized.

■ By making the cutting directions of the continuous slabs parallel to each other, the chamfering effect can be utilized on both end faces.

■ In the first pass of the rectangular hole type rolling row, the cutting direction is tilted approximately 451 degrees from the vertical direction, which is the condition for giving the minimum surface flaw position〇 (1) Same In this case, the condition for providing the minimum surface flaw position is to make the cutting direction perpendicular in the first pass of the box-shaped large-scale rolling train.

Based on these new findings, the method for hot rolling round section continuous cast slabs cut in-line by push-cutting of the present invention has a structure in which, in inline cutting of round cross-section continuous cast slabs, there is Indentation is performed using an upper and lower tool with a combined V cross-sectional shape that is divided into two parts, and then shearing is performed using a pair of opposing split piece tools of the upper and lower tools, and the first pass of the continuously cut slab is The main feature is that during rough hot rolling, the indentation shearing direction is orthogonal to the roll surface so that the cut continuous cast pieces are bitten.

In conjunction with the configuration of the main feature, the present invention also provides that the pushing shear direction is made parallel to each other on both end faces of the cut continuous slab, and that the rectangular large-sized rolling row of hot rolling is In the first pass, the continuously cut pieces are pressed so that the shear direction is inclined by about 456 degrees from the vertical direction, and in the first pass of the box-shaped large rolling row of hot rolling, Each method involves pushing the slab into the slab so that the shear direction is perpendicular.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

For comparison with the present invention, when a square cross-section material (1) with a normal end shape shown in FIG. 2(a) is rolled with a flat rolling roll, the rolled material (1a ), fishtail-like end deformation occurs, which causes an increase in crop loss. However, when rolling the square section material (2) with chamfered ends shown in Fig. 3 (a), Figure (b)
As shown in Figure 2, it is known that the rolled material (2a) has short fin tails and can reduce rolling crop loss in the final rolled product.

Figure 4 shows the end shape of the round section material (3) that has been sheared by pushing, Figure 4 (A) is a plan view, Figure 4 (B) is a side view, and Figure 4 p→ is an end face of 90 turns. In the figure, the edges are chamfered, but the deformation of the edges due to rolling is different from that of square cross-section materials, and is largely influenced by the direction of the material being bitten by the rolls.

Figure 5 (A) shows that the indentation shearing direction (3) of the round cross-section material (3) shown on the left is the same as the square hole shape (4r) of the upper roll (4) during the first pass rolling as shown on the right. The roll (5) and the same-hole mold (5) are shown in a state where the rolling direction and the angle are 0, and Fig. 5 (b) shows the same angle of <45°, and Fig. 5 ←→ shows the same angle of <90°. Fig. 6 shows the end shape of the rolled material (3a) (plasticine, 3 passes) in the case of Fig. 5 (a) (first pass biting direction of mouth IG/l). Figure 6 (a) shows the biting end, Figure 6 (b)
The position of the cutting edge of the bar, facing outward, is shown along with the above-mentioned biting angle numbers. This deformation state is caused by the concave shape deformation of the biting end of the rolled material shown in Fig. 7 (a) K from a round section material with a normal cut end for comparison, and the concave shape deformation of the biting end of the rolled material shown in Fig. 7 (b). This is clearly different from convex shape deformation.

From the above, in the first pass of the large-scale rolling train, the round cross-section continuous cast piece subjected to indentation shearing is set in the biting direction in which the indentation shearing direction is orthogonal to the roll surface, that is, the biting direction of 45 degrees as in the previous example, so that the final It is known that the surface flaw position of rolled products can be minimized at both ends.

It is known that during subsequent rolling, both end faces that have been chamfered always maintain the same orientation, so that the position of surface flaws can be controlled to a minimum in the same process for both end faces thereafter.

A specific example of the hot rolling method of the present invention is shown below.

FIG. 8 shows a large-sized roll (11) for this rolling, and its rolling pass schedule is shown in the following table.

Figure 9 shows the angle between the indentation shear direction of a round-section slab and the rolling direction during the first pass rolling on the horizontal axis υ, and the vertical axis the position of surface flaws from the end surface of the rolled material. Show relationships. 9th
Figure (a) shows the case of 60-V, 50-inch indentation shear,
Figure (b) shows the case of indentation shearing at 90°V and 50 inches. FIG. 9 (/→ is the case of a normal cut surface for comparison. In both cases, the results are shown for the biting end on the left and the cutting edge on the right.

It is a 3-pass plasticine.

Figure 10 shows the relationship between the two, with the horizontal axis as in Figure 9 and the crop loss weight on the vertical axis. The display classification is the same as in FIG.

As is known from these studies, during hot rolling, the continuous slab with a round cross section that has been subjected to in-line indentation shearing is moved in the indentation shearing direction of the continuous slab by about 45 degrees from the vertical direction in the first pass of the rectangular hole rolling row. By biting in an inclined direction, it is possible to make the surface of the slab at the part pushed by the V carving tool least likely to appear on the surface of the rolled product after hot rolling.

Because each normal large shape is 180, rather than 90.
Since it has a rectangular shape, the condition for providing the minimum surface flaw position is to set the indentation shearing direction of the continuous cast piece at a distance of about 45 degrees from the perpendicular direction.

Similarly, in-line push-sheared round section continuous slabs are
During hot rolling, in the first pass of the box-shaped hole type rolling row, the indentation shearing direction of the continuous cast piece is bitten in the vertical direction, so that the surface of the cast piece at the part pushed by the V carving tool will be smooth after hot rolling. It is possible to make it least likely to appear on the surface of the rolled product.

In summary, in in-line cutting, ■Even if the surface of the slab at the part where the shape tool is pushed is not maintained, the position of the surface flaws on the surface of the rolled product caused by this can be determined using ordinary gas cutting material or shear cutting material. 11 can be limited to the same level.

(Method of invention) According to the present invention, the following effects can be obtained.

(11 The advantage of the in-line indentation shearing method is that it eliminates material loss during cutting, and the area where surface flaws occur due to the surface of the slab at the indentation part of the cut continuous slab is reduced to the same level as gas cutting material. This makes it possible to further improve the overall yield.

(ill) It is possible to omit the step of scraping the surface of the slab at the push-in part of the continuous slab cut by the in-line push shearing method.

[Brief explanation of drawings]

Fig. 1 (a) is a side view of the starting state of indentation shearing, Fig. 1 (b) is a side view of the indentation state, Fig. 1 P → is a side view during the shearing process, and Fig. 2 (a) is a side view of the indentation state. Figure 2 (B) is a side view of the end of a square section material with a normal end shape, Figure 2 (B) is a side view of the end of the rolled material, and Figure 3 (A) is a side view of the end of a square section material with a chamfered end shape. Figure 3 (b) is a side view of the end of the rolled material, Figure 4 (a) is a plan view of the end of the round section material that has been pressed and sheared, and Figure 4 (b) is a side view of the end of the rolled material. Figure 4 (A) shows its side view, Figure 4 (A) shows its end view, and Figure 5 (A) shows the indentation shearing direction of the round-section material at an angle o.
Figure 5 (b) is the same view at 45 degrees, Figure 5 (c) is the same view at <90 degrees, and Figure 6 (a) is the state in which the rolled material is bited in the roll at 0. Figure 6 (b) is a diagram showing the deformed state of the end, and Figure 6 (b) is a diagram of the through-through end, and Figure 7 (a) is a diagram showing the deformed state of the biting end of a rolled material with a normal end face round section. (b) is also a diagram of the sheath end, No. 8
The figure shows the large shape of the roll used in the example, and Figure 9 (
A) is a diagram showing the relationship between the surface flaw position on the vertical axis and the biting direction angle on the horizontal axis in the case of 60° v 50% indentation, and Figure 9 (b) is a diagram showing the same relationship in the case of 9ov so% indentation. , the ninth cause! /-1 is a diagram showing the same relationship in the case of a normal cut surface, and Figure 1o (a) is a diagram showing the relationship between the clog loss weight on the vertical axis and the biting direction angle on the horizontal axis in the case of 60"V 50% pushing. , FIG. 10(B) is a diagram showing the same relationship in the case of q6v so% indentation, and FIG. 10(C) is a diagram showing the same relationship in the case of a normal cut surface. (1) +2)...Angle Cross section material, (Ia) (2a)...Rolled material, (3)...Round section material, (6a)...Rolled material, (4
)...Top roll, (5)...Bottom roll, +4) (5)
... Square hole shape, fl) (It) -- Hole shape, (a
)-・Slab, (bl) (b2)""Top tool, (cl)
(c2)...lower tool, (3)...indentation shearing direction.菰1 diagram guzun calculation 6 diagram! 1 Roku 5 diagram (Roku θ1) 7 diagram monk) Rin 8 diagram calculation 9 diagram 3 [1 (Ir6o″y h+2≦~ :w (I) ltf
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Claims (3)

[Claims] (1) In in-line cutting of round-section continuous slabs, indentation is performed using upper and lower tools with a combined V cross-section shape that are divided into two on the upstream and downstream sides of the slab transition, and then the upper and lower tools are continuously cut in opposite directions. Shearing is performed by a pair of split piece tools, and the cut continuous cast piece is bitten in such a way that the pushing shear direction is perpendicular to the roll surface during the first pass hot rough rolling of the cut continuous cast piece. A method for hot rolling a round section continuous slab cut by in-line push-cutting. (2) The hot rolling method according to claim 1, wherein the pushing shear directions are parallel to each other on both end surfaces of the cut continuous slab. (3) In the first pass of the hot rolling rectangular hole type rolling row, the cut continuous slab is pushed so that the shear direction is approximately 45 mm from the vertical direction.
The hot rolling method according to claim 1, wherein the hot rolling method is carried out in such a way that the direction is tilted. (3) Hot rolling according to claim 1, in which the cut continuous slab is pushed and bitten in the first pass of the box-shaped hole type rolling row of hot rolling so that the shear direction is perpendicular. Method.