JPS59178114A - Method for controlling plate camber in thick plate rolling - Google Patents

Abstract

PURPOSE:To perform rolling highly efficiently and without causing plate camber by controlling the pickup of a lower work roll in rolling a thick plate by a rolling mill equipped with independently liftable table-rolls arranged at the outlet and inlet sides of a pair of upper and lower work rolls. CONSTITUTION:A rolling material 5 is rolled by a mill having a pair of upper and lower work rolls 3, 4 and table rolls 6, 7 provided independently liftably to the front and rear sides of the rolls 3, 4. At that time, basing on a pass schedule to be determined at every pass, a rolling reduction, and the dimensions of a plate at the inlet side; the positions of the top faces of rolls 6, 7 are controlled so that the distances Xi at the inlet and Xi at the outlet between the top face of roll 4 and the top faces 8, 9 of rolls 6, 7 satisfy the equations I , II[DELTAH: a rolling reduction at a pass concerned, alpha: an adjusting amount to be added (0: at the time of initial pass)] respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling plate warpage that can effectively prevent plate warping that occurs on the exit side of a rolling mill during thick plate rolling.

During thick plate rolling, plate warping (upward warping, downward warping) often occurs on the rolling side of the plate material, which can damage the rolling mill and its front and rear equipment, leading to a shutdown of the rolling mill, or the need for the next step. (This may hinder the biting ability of the board and reduce productivity due to the time required to straighten the board. In addition, the warp may remain in the board itself, resulting in quality deterioration. In extreme cases, the effective end of the board may be damaged.) This causes great harm, such as having to cut and discard the sheets, which lowers the yield.However, the reality is that effective board warpage control technology has not yet been put into practical use.

The reason for this is that, at present, not all of the causes and mechanisms that cause plate warping are fully understood, and even if the causes are currently known, at most the top and bottom surfaces of the material Differences in deformation resistance due to the temperature difference between - or 1) Differences in surface properties between the upper and lower surfaces of the material (for example, differences in scale adhesion), Differences in the lubrication state between the material and the contact surface of the lower work rolls, ( j, ), t - Roughness difference, diameter difference and circumferential speed difference of the lower work roll, (6) Impact drop amount and difference in the rotation speed of the upper and lower work rolls when biting the material, ■ Reduction amount, plate thickness and plate It only mentions the relationship between the width and the peripheral speed difference between the upper and lower work rolls, and other factors such as the material's own weight, creep, lower work roll pick-up, etc., and in actual rolling, each of these factors is complex and complex at the same time. It is working as such. Therefore, it can be said that there is almost no quantitative elucidation, let alone quantitative elucidation of the influence of each individual factor on sheet warpage, or even qualitative elucidation. In addition, one of the reasons for this is that the sheet warping phenomenon itself has not been quantitatively understood online, and that there is little understanding of each of these factors online. It also depends on the fact that there are many possibilities.

Therefore, in reality, the circumferential speed difference between the upper and lower work rolls is controlled visually by the operator, and its effect is unclear and may not be effective at all.

In light of the current situation, the inventor of the present invention has conducted extensive research into elucidating the occurrence of sheet warpage and measures to prevent it. As a result, the inventor has found that the phenomenon of sheet ejection stretching during thick plate rolling is caused by the front and rear table rollers of the rolling machine. We found that the factor caused by the geometrical vertical asymmetry of the biting of the rolled material into the roll bit due to the level difference with the lower work roll is particularly large. Regarding the relationship between the top surface level (difference between the top surface level and the top surface level of the table rollers on the front and rear surfaces of the rolling machine) and the plate thickness, in the process of raising and lowering the lower work roll during rolling (during metal-in) during thick plate rolling, Assuming that when the work roll is raised, the material is clearly damaged, and on the other hand, the lower work roll big amplifier is extremely lowered to 0 to negative, the material (the lower work roll and the table roller are moved upward by 8 points). The present invention was completed based on the knowledge that controlling the bottom work roll pickup is effective in controlling the root warpage, since it can be easily estimated that it will warp due to bending.

The present invention provides relatively easy control of each of the above factors;
The purpose of the present invention is to provide a new sheet warpage control method that can be handled logically and quantitatively, and that actively controls the lower work roll pickup, which is considered to have a large influence on sheet warp. The gist of this is that a thick plate is rolled on the back of a rolling mill that has a pair of upper and lower pear rolls and is equipped with table rollers that can be pulled down independently on the entry and exit sides. In doing so, the distance xi between the top surface of the lower work roll and the top surface of the front surface r-pull roller and the rear surface daple are determined based on the pass schedule, rolling reduction amount, and entry side plate=j method determined in each pass. In thick plate rolling, the positions of each of the front and rear table roller top surfaces are controlled so that the distance x1 from the roller top surface satisfies the following formulas (1) and (2). Method for controlling warped cans.

x1 person=-7ΔH1+α(1) x1 out-〇(2) However, ΔH1: Reduction amount of the relevant pass α: Additional adjustment amount (initial) (when Let α−〇. ) At the point of

Hereinafter, the present invention will be explained in detail based on examples.The examples are examples of the case where the present invention is applied to a four-high rolling mill.

Fig. 1 shows a four-stage thick plate E rolling machine having a pair of upper and lower work rolls 8.4 and pick-up rolls 1, 2, and a table roller 6.7 on the entry and exit sides (11). This schematically shows a situation in which the rolled material 5 is rolled without warping.In FIG. 1, 8 indicates the top surface of the front table roller 2-6, and 9 indicates the rear table roller. 7, H person and H indicate the entrance side plate thickness and exit side plate f) of the rolled material 5, respectively, indicating that rolling is in progress in the rolling direction of the arrow. The top surface C, that is, the ejection point of the rolled material 5 at the lower work opening to the lower work hole 4 (in the case shown in which the sheet is rolled without warping, the intersection point with the center line of the upper and lower work rolls is 0)] was used as a reference. In this case, X people measure the distance from the top of the front table roller 6, and x people measure the distance from the top of the rear table roller 7, and
The x output is compared to the so-called lower work TJ-Rubbick up. Here, the case where the top surface of the table roller is adjusted at a position lower than the top surface of the lower work roll is assumed to be H people and H output <0.

A board battle with! In the rolling state without ll, when the rolled material 5 exhibits downward warpage on the ejection side of the rolling mill (Fig. 2),
) In some cases, the #4 direction is exhibited (Fig. 8).

The downward warping tendency shown in Fig. 2 is caused by the relationship of pink-up Occurs in certain cases, and conversely, 1χ person 1
(When there is a relationship of iΔH, as shown in FIG. 8) - a tendency to warp occurs.

The mechanism by which board warpage occurs depending on the number of people who pick up the bottom work roll will be explained with reference to FIG. 4 for the case of downward warp shown in FIG. In addition, in the figure, A and B are respectively the biting side contact start points of the rolled material 5 with the upper and lower work rolls 8 and 4, and C and D are the points where the rolled material 5 is connected to the upper and lower work rolls 8, respectively.
．． Shows the point that is bitten from 4. (A in Figure 2,
The same applies to B. ) The area surrounded by A, B, O, and D is the area that is being rolled by the upper and lower work rolls 8 and 4, and as shown in the figure, the upper work roll side and the lower work roll side of the rolled material 6 Compressive stresses σ8 and σL are generated on the sides, respectively, and as a result, σ
Due to the compressive stress difference of L-σU==Δσ, the upper work roll 8
A bending moment is generated on the lower work roll 4.

Also, if the positions of A and B in the rolling direction are l, then the additive tone!
The relationship with I quantity α, that is, IX person 1−7ΔH=α, is the fifth
The relationship is as shown in the figure.

Now, as shown in FIG. 8, if the weight of the input side rolled material 5 is P, the state of internal stress distribution in the rolled material 5 can be assumed as shown in the schematic diagram of FIG. In addition, in the figure, H indicates the plate thickness.Here, the internal stress distribution is expressed as y=ax
Assuming that, and balancing with the bending moment M, ・Equation 1%Formula %(8) Δσ・W=a−)i Therefore, l is set so that the internal stress per unit width is Δσ−〇. Control. That is, by controlling X people from the relationship between l and α shown in FIG. 5, it becomes possible to control the sheet warp without causing the sheet warp phenomenon.

・In addition, in the case of H release <o during hot rolling, the rolled material on the exit side of the rolling mill tends to slide downward due to its own weight or creep phenomenon, so the tip of the rolled material exit side is connected to the rear table roller. It is assumed that a situation will arise when the situation arises. In such a case, a steep liquid-like shape with a small pitch occurs in the rolled material on the exit side, which often cannot be corrected even with hot straightening.In this sense, the exit side is X-out: = = 0 It is also important to keep this in mind.

Next, examples of the present invention will be described.

First, an example of an apparatus used in the method of the present invention according to an embodiment is shown in FIG. This figure shows an example of a lifting mechanism for the front table roller 6 and the rear table roller 7, which is based on a wedge mechanism via idle rollers 10 and 14. Each idle roller is fixed to either a table roller 6.7 or a wedge-shaped intermediate frame 11.15 via a bearing base. It is placed with its lower surface in contact with a fixed idle roller 12.16, which has a sloped shape and is rotatably supported via a bearing frame installed on an absolute base. Furthermore, cylinders 1J17 are connected to each intermediate pedestal, and are moved appropriately in the direction of the arrow in the figure by these 7 cylinders).Therefore, each table roller 6.7 is raised and lowered via an idle roller 10.14. do. The lowering position of the table roller 6.7 is, for example, x, ! for servo valve and cylinder position detection. lll cylinder 18
．． Closed-loop control for controlling the position of 17 can be easily controlled with sufficiently high precision.

It should be noted that the above mechanism is just an example, and a system in which the system is operated by a hydraulic cylinder or an electric motor using a link mechanism or an eccentric wheel may also be adopted, and either method does not depart from the scope of the present invention.

An example will be described in which the above-described apparatus is used to control board warpage when the board actually exhibits a tendency to warp due to some other disturbance factors.

S? As shown in the figure for f4', the top surface level of each front and rear table roller is X input = -7ΔH + α (α = 0),
) (, j, = 0, so that the plate warpage is completely unchanged), even when rolling a thick plate under conditions such as As shown in FIG. 8(a), there are many cases in which ten warps occur. In such a case, as shown in FIG. 1AH+ a (α<9), X output=o
If α is appropriately selected as , and the top surface of the front table roller is controlled, rolling without warping can be performed. In this case, α can be determined by finding a value that satisfies Δσ=0 (see FIGS. 5 and 6) as described above.

As is clear from the above explanation, conventionally, when the work rolls are rearranged, the operation is completely stopped and the lower work rolls are raised and lowered in batches using electric screws, etc., and the pick-up amount is determined to be a constant value during rolling. In contrast, with the present invention, it is possible to control sheet warpage by appropriately controlling the rolling conditions of each bus during operation, and to adjust the top surface level of the rear table roller to match the top surface level of the lower work roll. This prevents the material from sagging due to its own weight on the exit side, and it is also possible to feed back the board warping results from each bus to correct the pickup position in the next pass, which eliminates the various problems in the prior art described above. Remarkable effects can be expected, such as solving problems at once, making it possible to roll thick plates with high efficiency without causing warping, and making it possible to manufacture high-quality thick plate products at high yields. .

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing the rolling state by a four-high plate rolling mill, and Figs. , 8 is a schematic explanatory diagram of the case where the rolled material exhibits a tendency to warp upward in the rolling mill shown in FIG. Figure 5 is a diagram showing the relationship between the biting start position difference l of the two lower work rolls and the lower work roll pickup α, Figure 6 is a diagram showing the state of internal stress distribution in the rolled material. Explanation - Schematic diagram of rolling. FIG. 7 is a schematic explanatory diagram showing a case where thick plate rolling is performed in a normal rolling state without sheet warping. FIG. 8 is sheet warping control according to the present invention. FIG. 2 is a schematic explanatory diagram showing an example, in which (a) is a diagram showing a case where upward warpage occurs, and (b) is a diagram showing how to control the pick-up of the lower work roll in the next pass or the bus in that case. FIG. l...Upper backup roll 2...Lower backup roll 8...Upper work roll 4...Lower work roll 5-
...Rolled material 6...Front table roller? ... Rear table roller 8 ... Front table roller top surface 9 ... Rear table roller top surface 10.14 ... Idle roller 11.15 ... Intermediate mount 12, 15 ... Fixed idle roller 18 , 17...
・Cylinder 18...Plate warpage detection device. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] ] A path determined in each pass when rolling a thick plate by a rolling mill having a pair of upper and lower work rolls and provided with table rollers that can be raised and lowered independently on the entry and exit sides. Based on the schedule, reduction amount and entrance plate dimensions,
The distance between the top surface of the lower work roll and the top surface of the front table roller A method for controlling plate warpage in thick plate rolling, characterized by controlling the positions of the top surfaces of each of the front and rear table rollers. X1 person knee iΔH1+α (1) X1 output −〇(
2) However, ΔH1: Reduction amount in the relevant pass α: Additional adjustment amount (α = 0 at the initial pass) The value of λ α will be negative in the case of upward warping, depending on the actual board warpage in the previous pass. 2. A method for controlling plate warpage in thick plate rolling according to claim 1, characterized in that, in the case of downward warpage, additional adjustment is made by making it positive.