JPH0399711A - Rolling method for preventing camber - Google Patents

Abstract

PURPOSE:To solve a problem generated during rolling with the camber of a steel plate, by executing rolling reduction in a specific thickness after passing a camber generation area, executing the rolling reduction of un-rolling reduction part at the following reverse pass time and executing rolling with the positive and reverse two passes in succession. CONSTITUTION:The member 1 to be rolled is fed into a rolling mill in the state of enlarging a roll gap S1 more than the plate thickness t1 of the member 1 to be rolled. No rolling reduction is applied on the member 1 in a camber generation area L and after passing this area L a roll gap S2 is narrowed to a specific gap and the member 1 is subjected to rolling reduction so as to become in a specific plate thickness t2. At the following reverse pass time, a roll gap S4 is narrowed in the specific gap immediately before the un-rolling reduction part of the member 1 to be rolled and the un-rolling reduction part is subjected to rolling reduction. The rolling reduction is thus executed with continuous positive and reverse two passes. Consequently, the camber generation in the camber generation area of the tip in the rolling direction of the member to be rolled can be prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to a method for generating warping at the tip of a rolled material in the rolling direction.
This relates to a rolling method that does not involve rolling.

<Prior art> Warpage of a steel plate that occurs during rolling not only causes bumping flaws against the rollers, increased straightening load, and uneven cooling after rolling, but also sometimes causes ilff damage. There is also a way to prevent warping from occurring.
- Methods of controlling the lower roll speed, pick-up amount, and temperature of the upper and lower surfaces of the steel plate can be considered, but in reality, it is extremely difficult to completely eliminate warping because it has no effect on warping and is caused by a wide variety of factors. It is.

<Problems to be Solved by the Invention> In view of the current situation that it is extremely difficult to completely eliminate warpage at the tip in the rolling direction with conventional rolling methods, the present invention has been developed by improving the rolling method, that is, in the longitudinal direction of the material to be rolled. This was done in order to provide a rolling method that does not cause any warping by changing the method of applying rolling force from the conventional method.

<Means for solving the problem> The warping phenomenon during rolling is caused by the difference in rotation speed between the upper and lower rolls, the biting angle, the difference in the friction coefficient between the upper and lower rolls and the upper and lower surfaces of the rolled material, the temperature difference between the upper and lower surfaces of the rolled material, The warpage occurs due to various factors such as the difference in deformation resistance in the direction of the rolling material and the j7 direction of the rolled material, but according to the observations of the present inventors, the warpage occurs only in an area of a certain length from the tip in the rolling direction as shown in Fig. 3. is limited to
It was found that beyond this area, no warping occurred up to the rear end in the rolling direction.

Based on this knowledge, we did not apply any reduction from the tip of the rolled material in the rolling direction to the length equivalent to the warp generation area, and performed rolling to apply reduction after the length equivalent to the warp generation area to prevent the occurrence of warp. It is something.

That is, in rolling in a reversible rolling mill, the present invention feeds the material to be rolled into the rolling mill with a roll gap wider than the thickness of the material to be rolled, and reduces the rolling distance from the tip in the rolling direction to a length equivalent to the warping region. Instead, after passing the length equivalent to the warpage area, narrow the roll gap to a predetermined gap and roll down to a predetermined plate IW, and during the next reverse pass, roll the material just before the unrolled part of the material to be rolled. This is a warpage prevention rolling method characterized by narrowing the roll gap to a predetermined gap, rolling down the unrolled portion to a predetermined thickness, and rolling in two consecutive forward and reverse buses.

<Effect> The method according to the invention will be explained with reference to FIG.

First, as shown in FIG. 1(a), the material to be rolled 1 is fed between the rolling rolls 2 with the roll gap SI widened by the thickness of the material to be rolled in the bus before rolling. rank;〃
The detector 4 detects the position of the tip of the material to be rolled 1, and thereafter tracks the position of the material to be rolled with respect to the rolling rolls.

Next, as shown in FIG. 1(b), the roll gap is adjusted so that the rolled material has a predetermined thickness L2 when the length L corresponding to the warp occurrence area of the rolled material passes through the rolling roll from the tip. 32, and then rolling is applied so that the material to be rolled has a predetermined thickness L2, as shown in FIG. 1(C).

Furthermore, as shown in FIG. 1(d), board 1! ir, t
A material to be rolled having a plate thickness of 1 part and a plate thickness of t and 2 parts is rolled with the roll gap S3 being wider than the plate 17L2 of the material to be rolled,
It is fed between the rolling rolls 2 in the opposite direction to the previous pass.

Furthermore, as shown in FIG. 1(e), by narrowing the roll gap to 34 so that the material to be rolled has a predetermined thickness t2 from the middle of the material to be rolled, the thickness of the material to be rolled is reduced by 1 part. is rolled down onto a predetermined plate 1\tz.

Through the series of two forward and reverse rolling passes described above, the rolled material, which had an initial thickness of ζ, can be finished to a predetermined thickness t2 with no warpage over the entire length of the rolled material.

If the rolling method according to the present invention is applied to a total of two buses, the final rolling bus and the final one pass, it is possible to manufacture a steel plate with no warping over the entire length in a rolled finish state,
Also, if applied to any two consecutive buses during rolling,
It is also possible to prevent warpage from occurring on buses en route.

As a result of various experiments by the present inventors, when rolling with this method, the rolling start position is at a ratio of L/l+ (t+: thickness of the material to be rolled) from the tip of the material to be rolled, as shown in Figure 2. If you ensure 35 or more, almost no warping will occur, and L/l
It has been found that no warpage occurs when , is set to 50 or more.

<Example> Next, specific examples of the present invention will be described below.

As a rolling mill, a four-high reversible rolling mill equipped with a hydraulic rolling device and having a work roll diameter of 1] and 50 mm was used.

As a position detector for the tip of the material to be rolled, a plate thickness measuring device installed at a position 2000 mm away from the center of the rolling mill was used. The material to be rolled is plate thickness: 32mm, plate width: 2200mm.
, Plate length: 15100mm, Plate thickness: 22m
The method according to the present invention was applied at the stage of finishing the plate to 2200 mm, plate width: 2200 mm, and plate length: 22000 mm.

■For the pass, the material to be rolled is sent to the rolling mill using a roll gear, and the hydraulic rolling device is applied from a position 3000 mm from the tip of the material in the rolling direction, where the length equivalent to the warpage area of the material to be rolled has passed through the rolling mill. Narrow the roll gap and roll opening S2 = 19.27
A pressure was applied in mm. Furthermore, during the second reverse pass of rolling in the opposite direction, the roll gap (S,) was set to 28 m.
The material to be rolled is sent to the rolling mill as m, and the length of the material to be rolled is 500 mm from the tip in the rolling direction (the tail end in the rolling direction of the first bus).
The roll gap was narrowed from a position of 0 mm using a hydraulic pressure reduction device, and reduction was applied at a roll opening degree S s = 19.13 mm.

An average sheet J'! is produced by rolling using the method according to the present invention as described in "2" below. A steel plate of -22 mm with no warpage could be manufactured. In addition, when using the same four-high reversible rolling mill as in the example to finish the rolled material with the same dimensions as in the example into a product with the same dimensions as in the example, if the conventional rolling method is used, the warpage of the steel plate will be on average. The diameter was 50 mm, and the minimum was 10+ nm.

<Effects of the Invention> According to the method of the present invention, as described above, no warping occurs in the warping region at the tip of the rolled material in the rolling direction, and therefore, problems that occur during rolling due to warping of the steel plate can be solved. Ta.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the rolling method according to the present invention, and FIG. 2 is an illustration of the rolling method according to the present invention.
Characteristic diagram schematically showing the relationship between the amount of warpage and L/l, 3rd
The figure is a schematic diagram showing how warpage occurs during rolling. 1... Rolled material, 2... Roll, 3...
・Rolling direction tip, 4...Position detector, Δ...Rolling direction, L...Warp occurrence area, tl...Plate 17 of the material to be rolled in the bus before rolling, L2...Top of the rolled material Predetermined plate thickness of rolled material, S,... roll gap (>1.1), S2...
(', LZ), S 3...
(> too . )
,S,... ('1LZ).

Claims (1)

[Scope of Claims] In rolling in a reversible rolling mill, the material to be rolled is fed into the rolling mill with the roll gap wider than the thickness of the material to be rolled, and no reduction is applied to the warping region from the tip in the rolling direction, After passing the warpage area, the roll gap is inserted into a predetermined gap and the plate is rolled to a predetermined thickness. During the next reverse pass, the roll gap is rolled to the predetermined thickness only just before the unrolled part of the material to be rolled. A warpage prevention rolling method characterized by rolling an unrolled portion between gaps so as to obtain a predetermined thickness, and rolling in two consecutive forward and reverse passes.