JPS603904A - Shape steel sheet having thick part at both ends and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a blank material for a pipe having increased wall thicknesses at its both ends to be manufactured without providing a special processing or an installation, by correctingly processing a rolled blank material provided with different thickness parts at the both ends by rolling it with a reversible steel-sheet rolling mill. CONSTITUTION:A slab of equal thickness is introduced to a reversing steel sheet rolling mill and is rolled through a reverse rolling pass on the way to the final 4-5 passes of rolling, to manufacture an original sheet whose prescribed lengths of both ends of the upper and lower surfaces are made to have the large thicknesses than its central part. And the original sheet is correctingly processed to make its one surface 4 flat and make the prescribed lengths (l) of both end parts of the other surface 5 have the thicknesses 5-1, 5-2 larger than that of its central part. From the shape steel sheet having thick parts at its both ends obtained by said process, a pipe having increased wall thicknesses at its both ends is manufactured without providing a special processing or an installation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deformed steel plate in which one side is flat and both ends of the other side are thicker than the center, and a method for manufacturing the same.

As shown in Figure 1, TLP is one of the marine structures.
As a welded steel pipe for (Ten5j, on Leg Plat, form), a steel pipe with a wall thickness t larger at both ends than at the center is used. This thick-walled pipe end portion is subjected to various processing such as bath welding W, and therefore has an important function to ensure processing allowance or strength.

Conventionally, such steel pipes are made by bending a thick plate 1 with a certain area and bath-welding it as shown in FIG. It is customary to process the pipe to obtain the thickened pipe 3 at the end. However, this method requires special processing steps and heating equipment, and is hardly a definitive manufacturing method in terms of productivity.

The purpose of the present invention is to economically manufacture the product without requiring special processing or equipment as described above.
, its gist consists of a deformed steel plate that is flat on one side and thicker at both ends of the other side than the center as a base plate for producing these pipes, and a method of rolling the deformed steel plate with a high yield using a reversible rolling mill. There is.

The present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 3 shows an overall view of the deformed steel plate according to the present invention, -
The surface 4 is flat, and the other surface 5 has a predetermined length 1 at both ends thereof, which is a thick portion 5-1 + 5-2. Such a steel plate is
As shown in FIG. 2B, with the flat surface 4 facing inside, the thick end portion 5-,
+ 5-2 is bent and welded to become the tube end.

By the way, in order to roll the deformed steel plate of the present invention.

One improvement is necessary in rolling. That is, the first point is that in order to directly obtain a thick plate with a cross section like that shown in Figure 3, it has been proposed to place the plate on a flat surface, apply pressure to the roll from above, and move the roll itself. However, this method requires a special purpose-built rolling equipment, which is not advisable and must be processed in rolling equipment used for ordinary thick plate rolling.

Therefore, in the present invention, a thick plate having stepped portions on both sides as shown in FIG. 4 is first rolled using a conventional rolling mill.

This is then processed into a deformed steel plate as shown in FIG. 3 by a method described later.

The second point is that when rolling a thick plate like the one shown in Figure 4 with a normal rolling mill, it is generally possible to roll it in one pass to several passes by moving the rolling cylinder up and down through the thickness control device of the rolling roll. Suggested. For example, FIG. 5 shows the displacement of the rolling roll gap in the longitudinal direction of the plate, and the rolling process is performed using such a forward rolling pattern.

However, as is well known, there are speed constraints on the response of the thickness control device, especially the cylinder as the operating end, so the sixth
As shown by the dotted line in the figure, a portion of the taper is partially formed, and the shaded portion becomes excess material, resulting in yield loss.

Table 1 is shown in Figure 6 (A: 11200+njn, tl
: 35mm, t2: 25+am, d: 100
The figure shows the yield loss for the substitute size (mm).

Table 1 To reduce these extra thicknesses, it is possible to stop the rotation of the rolls while the material is still in place and move the rolling down cylinder up and down, but this will damage the rolls and make it impossible to roll. Therefore, it cannot be adopted in practice. The present invention uses reverse rolling to solve this problem, as will be described later.

First, a method for rolling a thick plate having the shape and dimensions shown in Figure 4, which is the original plate of the deformed copper plate of the present invention, at a high yield will be explained with reference to FIG.

(1) From the 1st pass to the n-1th pass, conventional rolling is performed to obtain a thickness t1+Δt as shown in (71st prisoner-1). (2) In the n-th pass, rolling is performed with the roll gap Sn aiming at the plate thickness t1, and the rolls are reversed at point a (Fig. 7-2). Here, the purpose is to increase the thickness of the thick part at one end. Also, leaving the t1+Δt part at the other end is if the entire area is set to t.

It is impossible to grasp the rolling start point of the thin part.

In addition, there are two reasons why the length of the differential thickness portion (the tapered part) becomes large. (3) On the n + 1st pass.

At the same time as the roll reversal in (2), the AGO cylinder is used to narrow the roll gap to Sn+1, and the plate thickness is t2.
+Δt1 and after rolling to point b, the rolls are reversed (Fig. 7-3). In this pass, the thickness of the thin portion is brought closer to the target thickness t2. (4) At the n + 2nd pass, (3
) At the same time as the roll is reversed, use the 'A G C cylinder to narrow the roll gap to +2, and reduce the plate thickness to t2+.
After rolling Δt2 (Δ12<Δ1+) and rolling to point a, the rolls are reversed (Fig. 7-4).

Depending on the amount of thickness difference, this pass may not be necessary. Furthermore, if the difference in thickness is large, steps (3) and (4) may be repeated. (5) In the n + 3rd pass, roll out the plate to thickness t2 with the same roll gap as in the previous pass, and after rolling to bA, reverse the rolls (Fig. 7-5). This reversal eliminates the thickness taper of the differential pressure section. (6) At the n+4th pass, simultaneously with the roll reversal in (5), use the AGC cylinder to reduce the thickness of t, +Δt at the other end left in (2) by 1
．． Raise the roll gap to Sn+4.

The part of t1+Δt is rolled to reduce the thickness of the thick part to 1. out.

The rolling is completed (Fig. 7-6). Through this pass, the thickness of the remaining thick portion at the other end is determined.

- Figures 8(A) and 8(B) respectively show the change in shape of the difference in thickness between the top side and the bottom side in the pass. The numbers in the figure indicate the number of passes shown in the seventh figure.

The thickness control method involves first estimating the temperature of the rolled material, then calculating the reaction force based on the deformation resistance to assemble a base reduction schedule, and incorporating the cylinder reduction amount and the effect of mill reversal into it. , configure the reduction schedule for deformed steel plates. The reaction force is predicted from the inlet plate thickness and outlet plate thickness, and the roll gap is determined. As a method of controlling the rolling length, we introduce the concept of one volume being constant, and calculate the target length of each pass based on the target product length and the plate thickness of that pass.

FIG. 9 shows a deformed steel plate rolling system in which rotational pulses of the roll are counted by the PLG 6 from the time of biting, and based on the mill rotational speed at that time and the advance rate sent from the host computer 7.

The total rolling length is calculated within the length calculation device 8. When the target length of the pass calculated by the host computer is reached, the mill is reversed by the reversal control device 9 and controlled to the cylinder position instructed by the host computer 7.

By the above-mentioned method, an original plate as shown in the 41st threshold can be obtained with a high yield, but in order to shape this original plate into a deformed steel plate having a flat surface 4 on one side as shown in FIG. , is achieved by press straightening shown in FIG. 10, bending roller straightening shown in FIG. 11, etc.

That is, in Fig. 1O, molds (10-1) to (lO-3)
Forced bending towards the − blade side [1-2], half-turn bending [
3-4] and correction [5-6].

Further, in FIG. 11, the differential thickness portion is inserted between the rolls, bent once (A), and corrected by correction (B).

If steps remain on the lower surface of the correction, use a grinder.

Fig. 12 shows the actual measured dimensions (A) after rolling and (B) after press straightening.
; 6.5 +, ts: 4-5 +t,; 11.
j; 100 units mJ++), and it is clear that the shape correction has been performed with extremely high precision.

As explained above, according to the present invention, there is a rolling method for manufacturing a rolled material having a difference in thickness at both ends with a minimum yield loss, and it is possible to omit upset processing after pipe forming. This is an effective method that enables the production of thick-walled tube ends at low cost.

[Brief explanation of the drawings] Fig. 1 is a schematic diagram of a steel pipe with thick walled parts at both ends, which the present invention ultimately aims to obtain; Figure (B) is an explanatory diagram of the manufacturing process when using the deformed steel plate according to the present invention, Fig. 3 is a schematic diagram of the deformed steel plate according to the present invention, and Fig. 4 is an intermediate thick plate for obtaining the deformed female plate of the present invention. 5 is a schematic diagram of the conventional reversible rolling method, FIG. 6 is a schematic diagram of a deformed steel plate obtained by the conventional method, FIG. 7 is an explanatory diagram of the rolling method according to the present invention, and FIG. 7 is an enlarged view of a specific pass, and FIG. 9 is a schematic control diagram of a rolling mill for applying the rolling method according to the present invention. FIG. 10 is an explanatory diagram of the straightening process from an intermediate thick plate to a deformed steel plate using a press, FIG. 11 is an explanatory diagram of the straightening process using a bending roller, and FIG. 12 is an explanatory diagram of the actual shape of the thick plate. 6: PLG 7: Host computer 8: Length calculator 9: Reverse control device 1 Figure W Figure 2 (A) (B) Figure 3 Figure 4 Figure 5 Figure 6 T Negative Figure 70 Figure 1I (A) (8) “ii” Figure 12 (A) (β) 171

Claims (1)

[Claims] l - Thick at both ends, characterized in that the surface is flat and the predetermined length at both ends of the other surface is thicker than the central portion = ts-t
Deformed steel plate 2 A slab of equal thickness is introduced into the reversible steel plate rolling mill. During the final 4 to 5 passes of rolling, a reverse rolling bath is performed midway.
Obtain an original plate in which a predetermined length at both ends of the front and back surfaces is thicker than the center part.Next, the original plate is straightened so that one side is flat and a predetermined length on the other side is thicker than the center part. A method for manufacturing a deformed copper plate having thick portions at both ends, which is characterized by being straightened.