JPS5829509A - Controlling method for plane shape of thick plate - Google Patents

Abstract

PURPOSE:To control the plane shape of a thick plate accurately and to improve the yield of a material, by controlling a roll gap during rolling and together, performing the rolling while controlling the quantity of a lubricant to be supplied in accordance with the shape of the end part of the material to be rolled. CONSTITUTION:In a rolling of a thick plate containing a broadside rolling process, a cross sectional shape in the advancing direction of rolling of a material to be rolled is controlled by changing a roll gap during rolling for controlling a plane shape; next, in a pass of rolling process by turning the material 12 to be rolled by 90 degrees, the control of the plane shape is performed by supplying a lubricant to the roll bite. For this purpose, lubricant injecting nozzles 14-1, 14-2,..., 14'-1, 14'-2... are parallelly arranged in the direction of the barrel of a roll 13 on the material inlet side of a pair of rolls 13 used for rolling the material 12, and an injection quantity of every nozzle is controlled independently by operating flow-rate controlling valves 15-1,15-2,... in correspondence to the rear end shape of the material 12 detected by a shape detector 21 through an arithmetic device 24.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a planar shape control method in rolling a thick plate.

In plate rolling, after performing a forming pass in the longitudinal direction of the slab, the rolled material is turned to perform tentering rolling in the slab width direction, and then the rolled material is turned again to perform finish rolling in the longitudinal direction of the slab. It is true. Due to uneven material deformation in the width direction, the front and rear ends of the rolled material in the 7th rolling of the plate have a so-called fishtail, which is concave in the center of the width direction of the plate.
Or, it is common for a convex tank etc. to occur.

In this way, when cross rolling is performed for tentering, the non-uniformity of length in the width direction during tentering rolling may result in later finishing.
In the rolling process, the width becomes non-uniform, a so-called drum shape, a concave shape, or a camber, and the planar shape of the rolled product is impaired.

In order to control the planar shape during thick plate rolling, by changing the roll spacing during rolling, the cross-sectional shape of the rolled material in the rolling direction is controlled, and the rolled material is turned 90 degrees to reach the next process pass. A method of controlling the elongation distribution by changing the downstream rate in the rolling margin direction is known (Japanese Patent Laid-Open No. 52-57
061 bow or Japanese Patent Application Laid-Open No. 53-123358.

).

A method of changing the roll spacing will be explained with reference to FIG.

In the figure, it is assumed that all rolling is performed in the X direction. (1) represents the slab 1 taken out from the heating furnace, (2) represents the forming pass, and the rolled material 2 has been rolled from length Z'0 to 1'1. (3) is rolled (A2 is turned 90 degrees, and then subjected to tenter rolling (4) to make the width W.

Rolled from Wl to Wl. At this time, if the edge part of the rolled material 3 that has been tentered rolled is expected to have a tank shape as shown by the chain line, judging from the tentering ratio, when the forming pass (2) is completed as shown in the figure, Roll the rolled material 2 in a cross section parallel to the longitudinal direction so that the thickness at the center is thinner than at both ends,
On the other hand, if it is expected that the edge portion of the rolled material 3 that has been tentered rolled will have a fishtail shape with a concave central portion, the rolled material 2 may be rolled parallel to the longitudinal direction at the completion of forming pass (2). The cross section is rolled so that the thickness at the center is thicker than at both ends, contrary to what is shown in the figure. (4) represents the state of the rolled material 3' at the completion of tentering rolling (4), which is expressed as (
After turning 90 degrees as in step 5), the length is rolled from rl to 12 by finish rolling (6). At this time, too, if it is expected that the cropped part of the finish-rolled rolled material 4 will have a convex tongue shape at the center as shown by the chain line, judging from the tentering ratio, At the completion of rolling (4), the rolled material 3' is rolled in a cross section parallel to the width direction so that the center part is thinner than both ends, and conversely, the cropped part of the finished rolled material 4 is the center part. If a concave fishtail shape is expected, the rolled material 3' is rolled in the width direction so that the thickness at the center is thicker than at both ends in the cross section.

However, in this method, there is a limit to the gradient of change in the roll spacing in the rolling longitudinal direction due to the ability of the rolling device to change the roll spacing during rolling. In particular, in order to form the desired thickness distribution in the width direction of the rolled material 3' at the completion of tentering rolling (4), the capacity of downstream equipment is required because the rolling length of tentering rolling is short. Either it must be made extremely large or the rolling speed must be extremely slow. The former requires huge equipment costs, and the latter causes damage to the rolls and reduced productivity. In addition, this method only predicts the planar shape of the leading and trailing ends in the next pass after turning the rolled material by 90 degrees and controls the thickness distribution in the longitudinal direction in the previous process. (If the predicted leading and trailing edge east face shape cannot be obtained in that pass due to variations in J and other rolling conditions, control 111 of ``-'' is no longer possible.

On the other hand, in plate rolling, when a lubricant is supplied to the roll bit, the coefficient of friction between the roll and the rolled material becomes smaller.

By reducing this friction coefficient, the deformation of the material in the thickness direction of the rolled material is made uniform and the rolling efficiency is improved.
In order to reduce the rolling reaction force due to the frictional force in the roll barrel, the so-called friction hill, and to reduce the flattening of the roll and the amount of vertical movement of the roll axis, It is well known that it has the effect of increasing the amount of elongation in the longitudinal direction. Therefore, the present inventors have already published Japanese Patent Application Laid-Open No. 1986-54. No.-96455, Japanese Unexamined Patent Publication No. 1983.
No. 96456 proposes a method of controlling the planar shape of the leading and trailing ends of a rolled material using a lubricant. That is,
In these systems, a lubricant supply device is arranged in the direction of the roll barrel of a rolling mill, and the amount and timing of supply of lubricant at each position in the direction of the roll barrel are controlled to control the planar shape of the leading and trailing ends of the rolled material.

The present invention uses a method of controlling lubricant supply in the roll barrel direction in combination to compensate for the drawbacks of the method of controlling the planar shape of a thick plate by changing the roll interval during rolling, and as a result of the combined use of both methods. It is an object of the present invention to satisfactorily control the planar shape of a rolled material after finish rolling.

Next, the method according to the present invention will be explained together with a thick plate rolling machine as an example of its application.

First, as shown in FIGS. 2 and 3, the rolling mill 11 rolls the rolled material 12 (the material entry side of the pair of rolls 13).
In the state shown in FIG. 2, the rollers are arranged in parallel in the width direction of the rolled material 12, that is, in the barrel direction of the roll 13, facing the rolled material 12 and sandwiching it from both upper and lower surfaces. Two rows of lubricant injection nozzles 1.4
, 14'. Each injection nozzle 14-1
, 1-4-2.

...14-n, I4'-1, 14'-2,...
・The port 14' is divided into an appropriate number of sections, and remotely controllable flow rate control valves 15-1, 15-2, . . .
1.5-n, 1.5'-1,.

15'-2, . . . 15'-n. Furthermore, these flow rate control valves 15-1. ...15 n,
15' 1. .

15'-+1 is a -wood pipe connected to a pump 23 and a lubricating oil tank 17 via a remotely controllable on-off valve 16. In addition, in FIG. 2, on the material exit side of the roll 13 (the right side in the figure. If the flow of the rolled material 12 is in the opposite direction, the right side is the material input side), there is also an injection nozzle 18 as in 1. -], , 18-2゜18-n, 18'-
1, 18'-2, . . . 18'-n are provided, and each injection nozzle 18-1.・・・18-n, 18'-1,・
・18-n is also divided into an appropriate number of sections and remotely controllable flow rate control valves 19-1, 19-2, ・19
-n, 19'-1, 19'-2,...19'-n
The pump 23 and the lubricating oil tank 17 are connected to the pump 23 and the lubricating oil tank 17 via the on-off valve 20.

The operation of the flow control valves 15, 15', 19, and 19' is controlled according to the shape of the entrance rear end of the material detected in the previous pass. That is, if the rear end shape is a concave shape, a so-called fishtail, the amount of lubricant supplied to the central portion of the plate width is increased, and conversely, if the rear end shape is a convex shape, so-called a tank, the amount of lubricant supplied to the end portions of the plate width is increased. These flow control valves 15, 15'
, 19 and 19' are performed by using a shape detector 21 (for rolling in the opposite direction) that detects the rear end shape of the rolled material 1 on the material entry side of the roll 13 (shape detector 22 for the flow of "1" in the reverse direction). The calculation is automatically performed via the arithmetic unit 24 according to the output of the shape detector 21.

First, we will show the results of a basic experiment using a small hot rolling mill. The rolling mill has a second roller at an appropriate position in the width direction on the entry side of the roll.
The moisture i't'F agent supply means is arranged in the same manner as in FIGS. The rolled material used was a steel plate machined so that its cross-sectional shape in the direction perpendicular to the rolling direction was as shown by the solid line in FIG. The cross-sectional shape shown in FIG. 4 was machined assuming the cross-sectional shape obtained when the roll spacing was changed during tentering rolling in actual thick plate rolling. In other words, assuming the reduction rate in the subsequent finishing rolling, the ideal cross-sectional shape that should be imparted in the tenter rolling is the shape shown by the broken line in Figure 4, but due to the capacity limit of the rolling equipment and the width Due to the short rolling length of rolling,
This is because a cross-sectional shape that deviates from the ideal shape is often obtained, as shown by the solid line in the figure. Other rolling conditions are shown in Table 1.

The first surface rolling was performed in three passes from the same direction. The planar shape of the rear end of the rolled material is shown in FIG. (a) shows the case where no lubricant was supplied, and a large concave shape of approximately Bozm appears. (b) shows a case where lubricant is supplied to the central part of the plate width according to the present invention, and a good rear end shape with almost no unevenness is obtained.

EXAMPLE An example will be shown in which the rolling mill shown in FIGS. 2 and 3 was used. The main rolling conditions are shown in Table 2.

The second fruit rolling was performed in the same process as shown in FIG. The tentering ratio of 2.08 is based on the previously referenced Japanese Patent Application Laid-Open No. 53123358.
According to the publication, when a flat rectangular rolled material is subjected to tenter rolling, the edge shape of the rolled material is as shown in Fig. 1 (4).
), which means that it will have a tongue shape as shown by the chain line, and that the width change between the center and the ends will be in the order of about 70.

This amount of width change corresponds to about 2.2% of the finished product width of 3180 mm, so the forming pass, which is the pre-process of tentering rolling (4), is changed to the longitudinal cross-sectional shape of the rolled material 2 at the time of completion (2). This was done while controlling the roll spacing so that the thickness of the sea urchin was about 2.2% thinner in the center as shown in the figure. The surface roller of the rolled material 2 whose cross-sectional shape was controlled in this way was subjected to tenter rolling, and even when no lubricant was supplied, a generally good planar shape was obtained, but it became a tongue shape of about 10 mm. When the lubricant according to the present invention was supplied in the pass immediately before the final pass of tentering rolling, the planar shape was further improved, and a nearly perfect rectangular shape was obtained.

Furthermore, according to the same reference publication, the ratio (= Lp/(p)
= 9/2.08 = 4.3 means that the average crop length will be approximately 580 am. This crop length corresponds to about 2.2% of the finished product length of 27,000 am, so the tentering rolling, which is a pre-process of finish rolling (6), is performed at the end of the rolled material 3' in (4). The cross-sectional shape in the width direction is about 2.2% thinner at the center as shown in the figure.
Controlled roll spacing. When the rolled material 3' whose cross-sectional shape was controlled in this way was subjected to finish rolling, it turned out to be 711, l
When no lubricant was supplied, a concave shape of approximately 300 mm was formed at the front and rear ends of the rolled material, as shown by the chain lines in FIG. On the other hand, when the lubricant according to the present invention was supplied during this finish rolling, a good east face shape of the leading and trailing ends with almost no unevenness was obtained as shown by the solid line in FIG. As a result, the yield when cutting F-shaped thick plates from rolled products was 94 to 95% using the conventional method that only controlled the roll spacing, but when using the present invention and lubricant supply. was improved to 96-97%.

As described in detail below, the method for controlling the roll spacing during iJ rolling of the present invention involves supplying a lubricant to the rolled material while controlling it in accordance with the end shape of the rolled material. Since the method of performing this method is used in combination, the control accuracy can be greatly improved compared to the case where the east face shape of the plate is controlled only by the method of controlling the roll interval during rolling. Since the lubricant supply pattern (") can be selected arbitrarily, the present invention (")
Any type of control error in the method of controlling the roll spacing or variation in rolling conditions can be addressed, thus improving the planform shape of the plate and significantly increasing the yield of the material. can.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a series of steps in a rolling method for changing the roll spacing, FIGS. 2 and 3 are a plan view and a schematic configuration diagram showing a rolling mill used in carrying out the present invention, and FIG. FIG. 5 is a cross-sectional view of the rolled material sample used in the basic experiment in the direction orthogonal to the rolling direction, and FIG. by, No. 6
The figure is a plan view showing a rolled material after finish rolling in an example. 1...Slab, 2...Rolled material with a changed cross-sectional shape in the length direction, 3' 1■ Rolling mill with a changed cross-sectional shape in the width direction, 11...Rolling mill, 13... roll,] 4
, ] 4', 18, 18'... injection nozzle. +IIrfr Applicant Kobe Steel Co., Ltd. Agent ↑Tsuboshi Aoyama, 2 people Sogai Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 53-

Claims (1)

[Claims] (1) In plate rolling, including the tentering rolling process, the cross-sectional shape of the rolled material in the rolling direction is controlled by changing the roll spacing during rolling, and in the next process pass in which the rolled material is turned 90 degrees, the roll Planar shape control of a thick plate characterized by arranging a plurality of lubricant supply means in the barrel direction and rolling while controlling the supply amount and/or supply timing of the lubricant in relation to the end shape of the rolled material. Method.