JPS5857247B2 - Method for preventing meandering of rolled material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing meandering of a rolled material during rolling of a plate material.

Meandering of rolled material in plate rolling is a phenomenon in which the passing position of rolled material between stands or directly below the rolling stand is shifted to either the left or right in the width direction of the plate from the center of the normal threading line, which reduces rolling work efficiency. This is one of the important issues to be solved.

The main cause of meandering is that the rolling reduction or elongation rate on the left and right sides of the rolled material is different, and the rolled material is drawn to the side with smaller elongation.

Therefore, in the past, in order to equalize the rolling reduction or elongation rate on the left and right sides, the amount of rolling on the left and right sides was changed, or
5) The roll pending force was adjusted independently on the left and right sides.

However, in the former case, the rolling load itself changes, which adversely affects the accuracy of the plate thickness in the longitudinal direction.

In the latter case, there is a limit to the control ability, and a sufficient meandering prevention effect cannot be obtained.

In addition to the method described above, a method has also been considered in which the side guides are moved l in the width direction of the sheet and the entire rolling line is shifted in the direction in which the meandering occurs.

However, according to this method, the positions of the tension reel and the payoff reel must also be moved, and there is a drawback that the equipment becomes unstable, especially in the case of a Kundem rolling mill or the like.

In order to solve the problem of preventing meandering as mentioned above, recently,
A method has been developed that utilizes a new type of six-high rolling mill with axially movable intermediate rolls.

In this method, at least one of the movable intermediate rolls is moved in the direction in which the rolled material meandered, and the roll position is asymmetrical (this arrangement prevents the rolled material from meandering). .

However, in this method, both the roll bending effect and the intermediate roll position mutually influence the roll deformation characteristics, so if the intermediate roll position is changed, the roll pending force will also be asymmetric. This poses a problem in that control becomes extremely complicated and spalling tends to occur at the portion of the reinforcing roll that contacts the end of the intermediate roll.

This invention solves the above-mentioned problems in preventing meandering during sheet rolling, and it is an extremely simple method for rolling materials that does not cause a decrease in sheet thickness accuracy in the longitudinal direction and does not adversely affect the reinforcing roll surface. The purpose is to provide a meandering prevention method.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings.

FIGS. 1 and 2 are schematic diagrams showing an example of a rolling mill for carrying out the method of the present invention.

In the figure, known roll benders 7 and 7' are interposed between the left and right ends of upper and lower work rolls 2 and 2', respectively.

Further, sleeves 4 and 4' are loosely connected to the upper and lower reinforcing rolls 3 and 3', respectively, and the reinforcing rolls 3 and 3' contact the work rolls 2 and 2' via the sleeves 4 and 4', respectively. .

The sleeves 4 and 4' have an inner diameter slightly larger than the outer diameter of the reinforcing rolls 3 and 3', are rotatable around the reinforcing roll axis, and are movable in the axial direction of the reinforcing roll.

In the rolling mill configured as described above, during the rolling operation, the sleeves 4 and 4' are rotated simultaneously with the reinforcing roll by friction with the work roll 2 or 2', respectively.

The sleeves 4 and 4' are also moved independently in the axial direction by sleeve shift devices 6 and 6/, respectively.

The method of the present invention is carried out using a rolling mill configured in this manner.

That is, the sleeves 4 and 4' are positioned at a predetermined axial position depending on the width of the rolled material 1.

Then, the right and left roll pending forces are adjusted according to the meandering of the rolled material 1 to prevent meandering.

Figure 3: Sleeve position δ and optimal roll pending force F.

The graph shows the relationship between In this graph,
The sleeve position δ represents the distance in the width direction of the rolled material between the side end surface of the rolled material 1 and the side end surface of the sleeve 4 or 4',
When the sleeve side end surface is located outside the rolled material side end surface, it is called "correct".

Therefore, as illustrated in FIG. 1, when the sleeve end position is located inside the end surface of the rolled material, δ (δ1, δ2) takes a negative value.

Generally, the upper and lower sleeve positions δ1. δ2 may be different, but unless there is a special reason, the upper and lower δ values should be the same,
Normally, the upper and lower sleeves are arranged symmetrically, and the results shown in Figure 3 are δ and the optimum roll pending force F in this case.

Illustrate the relationship between Also, the optimal roll pending force F
.

is a roll bending method in which the rolled plate becomes flat, and is expressed as the load per chock.

As is clear from this graph, the sleeve position δ and the optimum roll pending force F.

There is a linear relationship between .

Set it to .

The sleeve position δ is set based on the relationship shown in FIG.

[On the other hand, if the plate width and rolling load are detected and become known values, the optimum roll pending force F is determined.

is determined, and the left and right roll pending forces are set to this value.

FIG. 4 is a schematic view showing the meandering direction when a material having a rectangular cross-section and thickness is rolled within a left-right asymmetric roll gap.

From the figure, the elongation in the longitudinal direction increases as the rolling reduction increases on the left side.
It means meandering to the right.

FIG. 5 shows an example of the asymmetric thickness distribution of the rolled material 1 when only the roll pending force on the left side is changed, as an example when the upper and lower sleeve positions δ are the same. It is shown that the effect of force on asymmetric plate thickness control is extremely strong.

In a conventional four-high rolling mill, for example, the roll body length of the work roll is equal to that of the reinforcing roll, so the ends of the work roll come into contact with the reinforcing roll, making it difficult to bend the work roll significantly.

Therefore, there is a limit to how effectively the meandering of a rolled material can be controlled using the roll bending method.

In this invention, as described above, a sloop is interposed between the work roll and the reinforcing roll.

Position of sleeves 4 and 4' in Fig. 1 (axial direction)
is in place, the upper and lower sleeves 4 and 4
' are located closer to the center than the side end surface of the rolled material 1 by δ1 and δ2, respectively.

Therefore, the right end of the lower work roll 2' is more likely to curve than the left end of the upper work roll 2.

Here, operate the roll bender to bend the work roll,
For example, when the roll gap at the left end of the work rolls is expanded, the rolled material becomes thinner on the right side and thicker on the left side, as shown in FIG.

Therefore, the rolled material has a large elongation rate on the right side in the width direction, and is subjected to a force that causes it to be displaced to the left as seen in FIG.

The above explanation is based on the upper and lower sleeve positions δ1. I explained that δ2 is generally different, but this is as explained previously (this,
Unless there is a special reason, there is no essential difference in the effects of the present invention even if they are made equal.

In addition, in the above explanation, in order to intuitively understand the effect of the present invention, the case where the sleeve is located inside the end surface of the rolled material is considered. By doing so, a free gap is created between the work roll and the reinforcing roll, thereby increasing the effectiveness of the roll bender.

That is, in this invention, since the portion of the work roll near the shaft end that does not contact the sleeve can be freely displaced, it can be largely curved, and the control capability is expanded to a state where there is virtually no limit.

The prevention of meandering of the rolled material mentioned above is actually carried out automatically.

Next, I will explain how to do that.

FIG. 6 shows a block diagram of the meandering prevention control device.

In the figure, when the plate width B of the rolled material is set by the plate width setter 8, a signal of the plate width B is sent from the calculators 9 and 11.

The calculator 9 calculates the sleeve position δ according to the plate width B.

is calculated and a sleeve shift signal is sent to the sleeve shift command device 10, and the sleeve shift signals 6 and 6' move the sleeves 4 and 4' to predetermined positions based on the signals from the sleeve shift command device 10.

On the other hand, the arithmetic unit 11 detects the plate width B and the rolling load detector 16.
Detected value from 16' and sleeve position δ from calculator 9.

The roll pending force F is input.

Calculate. And roll pending force command device 1
2 is the left and right roll pending force F based on the roll pending force signal received from the calculator 11;

Set to . During rolling work, the meandering of the rolled material 1 is detected by a meandering detector 15 using a photoelectric element array, a radiation device, etc., which detects deviation in the sheet width direction from the normal passing position of the sheet edge (half the width of the sheet at the line center). It is measured from moment to moment using methods such as measuring .

The detected value y is then sent to the arithmetic unit 131, where a correction value ΔF of the roll pending force is calculated.

The roll pending force command device 14 receives the signal of the correction value ΔF from the calculator 13 and causes the left roll bender 7' to correct the roll pending force.

On the other hand, if it meandered to the right, correct the roll pending force on the right side.

In this way, by correcting the roll pending force of the roll penters 7 and 7' in accordance with the meandering of the rolled material 1, the meandering of the rolled material 1 is reduced to a level that does not cause any trouble in the rolling operation.

As explained above, in this invention, the meandering of the rolled material is detected during the rolling operation, and the roll pending force of the roll bender is adjusted based on this detected value.
It is extremely simple and has quick response.

In addition, in order to prevent meandering (the rolling reduction rate is not adjusted), there is no adverse effect on the precision of the pinus in the longitudinal direction.

Furthermore, in the method of the present invention, instead of interposing an intermediate roll that is movable in the axial direction between the work roll and the reinforcing roll, the reinforcing roll (the sleeve) is loosely engaged with the reinforcing roll.

Therefore, the reinforcing roll and the sleeve are in contact with each other on their convex and concave surfaces (the contact pressure between the two is significantly smaller than that between the two convex surfaces, and spalling does not occur on the reinforcing roll as described above). .

In addition, sleeves can be made of high-quality materials using centrifugal casting, and can easily be made with high strength and durability.

Note that the work roll and sleeve are in contact with each other on convex surfaces, so there is a risk of spalling, but the work roll is frequently replaced, and the diameter of the work roll is smaller than that of the reinforcing roll. In comparison, it is possible to use high-hardness materials and has excellent spalling resistance, so there is no problem with the work roll (the loss due to replacement of the roll is significantly smaller than that of the reinforcing roll).

[Brief explanation of the drawing]

FIGS. 1 and 2 are a schematic front view and a schematic side view, respectively, showing an example of a rolling mill used to carry out the method of the present invention. FIG. 3 is a diagram 7 showing the relationship between sleeve position and optimum roll pending force. Fig. 4 is a schematic diagram illustrating the meandering of rolled material due to changes in roll pending force. Fig. 5 is a graph showing the relationship between roll pending force and change in plate thickness in the width direction. FIG. 2 is a block diagram of a meandering prevention control device that implements the method of the present invention.

Claims (1)

[Claims] 1 At the left and right ends of the work rolls (in a rolling mill in which a roll bender is provided and reinforcing rolls are arranged above and below), sleeves are loosely fitted to each of the reinforcing rolls so as to be rotatable and movable in the axial direction. is positioned at an axial position corresponding to the width of the rolled material, the meandering of the rolled material is detected during the rolling operation, and the left and right roll pending forces are adjusted independently based on the detected value O. A method for preventing meandering of rolled material, characterized by preventing meandering.