JPS6015402B2 - Rolling mill control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a rolling mill, and particularly to a method for controlling a rolling mill, and in particular, to control the rolling load when the rolled material is coughed into the work rolls of the rolling mill before the rolled material is coughed into the work rolls of the rolling mill. The present invention relates to a method of controlling a rolling mill that uses the predicted value to set the roll function of the work rolls so that the thickness of the material after rolling becomes a desired value.

Conventionally, various studies have been conducted regarding lubricants that lubricate the contact surface between a material to be rolled and a rolling mill work roll.

For example, as shown in FIG. 1, regarding the amount of lubricant drawn between the rolling mill work roll 1 and the rolled material 2, Mr. Mizuno (
Plasticity and Processing 7 (66), 383 (1966)) expressed the oil film thickness at the inlet of the roll bite using the following formula {1'.

Chi=3ri (U.

Ten U. ) ………(1)〇・〇y However, Uo: Roll circumferential speed U,: Material inlet speed Q: Coughing angle oy: Yield stress stress: Lubricating oil viscosity at pressure P {1' Formula is the lubricant This shows that the amount of lubricant drawn between the roll and the rolled material changes depending on the viscosity, rolling speed, cough angle, yield stress, etc.

Furthermore, it is known that the friction coefficient between the roll and the rolled material and the rolling load vary greatly depending on the amount of the lubricant.

For example, according to a study on the lubricity of beef tallow (material from the 54th Rolling Theory Subcommittee), the relationship between the concentration of a liquid beef tallow component added to a lubricant and the average rolling pressure is shown in FIG. The axis in Figure 2 shows the concentration [wt%] of tallow-based lubricating oil when a mixture of key oil-based lubricating oil and beef tallow (liquid content only)-based lubricating oil is used as a lubricant, and the vertical axis shows the average rolling The pressure [k9/fence] is shown, but as the concentration of tallow-based lubricating oil increases,
The average rolling pressure is decreasing.

This is because changing the concentration of tallow-based lubricating oil changes the viscosity of the lubricant and changes the amount of lubricant drawn between the roll and the rolled material, which is expressed by equation {1-. This is thought to be because the friction coefficient between the rolled materials changes and the average rolling pressure changes.

The relationship between the lubricant and the coefficient of friction and the relationship between the lubricant and rolling pressure have been known for a long time, but since the lubricant composition does not change significantly during rolling, it is important to control the rolling mill. especially,
Setup control (hereinafter abbreviated as setup control) sets the roll speed of the rolling mill so that the plate thickness reaches the target value after rolling the material to be rolled before the rolling mill coughs up the material to be rolled.

) does not take into account the characteristics of the lubricant at all, and
There was no need to consider this in the setup control of steel rolling. In traditional setup control for steel rolling, changes in lubricant properties could be ignored, but in recent years, setup control for hot rolling of aluminum and other materials has begun, and changes in lubricant properties have become more important. Can no longer be ignored due to setup control.

A characteristic of aluminum hot rolling is so-called roll coating, in which aluminum particles that fall off from the aluminum surface of the rolled material adhere to the work roll surface.The amount of roll cornering depends on the characteristics of the lubricant. Furthermore, the amount of roll coating greatly changes the friction coefficient and rolling load. Generally, the lubricant for aluminum hot rolling is a 3-10% aqueous solution based on natural oil, with the addition of emulsifiers, petroleum sulfonic acid, etc., but it is this lubricant that provides the lubricating effect between the aluminum and the work rolls. This is the oil component of the lubricant that separates from water when it comes into contact with high-temperature aluminum materials or rolls.

In other words, the lubrication effect of hot rolling is due to the oil that is thermally separated and adhered to the roll surface, and the lubrication effect varies depending on the thermal separability of the lubricant. Therefore, the amount of roll coating changes depending on the thermal separability of the lubricant, and the average rolling pressure or rolling load changes.

As an example of this experiment, the characteristics shown in FIGS. 3 and 4 are known. Figure 3 shows the relationship between rolling distance and roll coating amount, where A is a curve showing the characteristics of rolling oil that is classified as "low thermal separation" and B is a curve that is classified as "high thermal separation." This is a curve showing characteristics related to rolling oil. FIG. 4 shows the variation in rolling load with changes in rolling distance and roll coating amount with a solid line, and the relationship between rolling distance and rolling reduction rate with a broken line. A and B in Figure 4 are A and B in Figure 3,
The characteristics of each lubricant when using a lubricant corresponding to lubricant B are shown. If you pay attention to FIG. 3, you will see that using a lubricant with "high thermal separation" has a higher lubrication effect, making it difficult for the amount of roll coating to grow.

In addition, in Figure 4, B is the case when a lubricant with "high thermal separability" is used, and A is when a lubricant with "low thermal separability" is used.
It can be seen that the change in rolling load is smaller than the rolling distance. This is thought to be because the coating grows more slowly when lubricant B with "high thermal separation" is used. Furthermore, since lubricant B with “high thermal separation” has a higher lubrication effect than lubricant A with “low thermal separation,” the reduction ratio is larger than that with lubricant A with “low thermal separation.” Despite this, the rolling load is small. The characteristics shown in FIG. 4 are obtained by rolling a coil heated to 50,000 ℃, using 2-nail material as the rolling material, and having an entrance plate thickness of 2 dia and a plate width of 5 dia.

The temperature of the rolled material at the exit side of the rolls is 240 to 270 qo, and the rolling oil used is one with a temperature of 50° C. and a concentration of 5%.
As mentioned above, in steel rolling, the lubricating effect of lubricants simply affects the coefficient of friction between the rolled material and the work rolls, and the lubricant properties change as the lubricant composition changes. Unless there is a large change, it will not affect the rolling load or other rolling characteristics. However, in aluminum hot rolling, the lubricant's lubrication effect changes the amount of roll coating and has a synergistic effect with the lubrication effect of the lubricant itself. This changes the rolling load. Therefore, the influence of the lubricating effect of the lubricant on the rolling load cannot be ignored in the setup control of hot rolling of aluminum or the like.

For example, Fig. 4 shows the results of an experiment conducted with the lubricant condition or lubricant effect constant. FIG. 5, which shows the relationship between the rolling distance (equivalent to the rolling distance) and the actual rolling load, is quite different from the case in FIG. 4.

Figure 5 shows the relationship between the number of rolled rolls and the rolling load after changing the rolls of a rolling mill.At the first roll change of a rolling mill with no roll coating on the rolls, the rolling load is approximately It is 50% larger. This is because the lubrication characteristics of the rolls and the material to be rolled vary greatly when the rolls of the rolling mill are changed, even though the same lubricant is used.

When the first roll is changed, the lubricating properties of the rolling oil change and the rolling load changes significantly. A similar phenomenon also occurs when rolling is stopped for a long time. However, the lubrication characteristics of the lubricant are not reflected in the setup control of rolling mill rolls at all, and when the lubrication characteristics change, the rolling load prediction error of setup control is large, resulting in , the plate thickness accuracy had deteriorated.

The object of the present invention is to take into consideration the influence of lubricant on rolling as described above, and to set and modify the roll opening degree in order to obtain desired dimensions, thereby obtaining a rolling mill with high precision. The goal is to provide the following. In addition, in the case of Figure 5,
The rolling material used was JIS-specified grade 1100, and the rolling conditions were as follows: entry side thickness: 15 mm, exit side thickness: 9 mm, width of both input and exit sides: 90 mm, and entrance temperature: 41,000 to 420°C. FIG.

Next, the basic idea of the present invention will be explained in detail.

Setting up control of a rolling mill means, for example, predicting the rolling load P before the rolling mill rolls the material to be rolled, and controlling the rolling mill using a known gauge meter method so that the thickness of the rolled material reaches the target value h. In the control to set the roll function S of
P/k......[2] k: Spring constant of rolling mill By considering the lubricant properties of the lubricant in predicting the rolling load,
The objective is to improve the accuracy of rolling load prediction and reduce the difference between the plate thickness after rolling and the target value.

In particular, in cases such as hot rolling of aluminum, where the rolling load fluctuates by as much as 50% due to the lubrication properties of the lubricant, it is necessary to significantly improve the accuracy of rolling mill setup control. . Of course, the concept of setup control can also be applied to correction control during rolling and adaptive control based on actual values. In actual rolling, the composition of the lubricant changes somewhat after long-term rolling due to reasons such as oxidation of the rolling oil and the contamination of the lubricant with particles from the rolled material, but disturbances in the setup control of the rolling mill change. The lubricating properties of the lubricant will not change as rapidly as the

However, the following things became clear when performing setup control for aluminum hot rolling. In other words, if the surface temperature of the roll of the rolling mill or the temperature of the lubricant decreases due to rolling mill roll changes or long-term rolling suspensions, the lubrication properties will deteriorate, and the rolling load will increase while the amount of roll coating increases. This means increasing the Generally, the lubricant after use is collected, cleaned by a cleaning device, and reused, so the temperature of the lubricant is usually between 50qo and 60 qo during rolling.
The temperature is maintained at 0oo, but if there is a long pause in rolling, the temperature will drop to room temperature.

In addition, the surface temperature of the rolls of a rolling mill is normal temperature after a roll change or after a long rolling pause, but it rises due to the rolling load and contact between the rolls and the hot rolled material, and during normal rolling it reaches around 100 qo. Become. For example, in an actual finishing mill for aluminum hot rolling, the surface temperature of the roll is
The results measured each time the book finished rolling are shown in Figure 6. In Figure 6, the cross section is the number of rolls rolled after changing the rolls,
The vertical axis shows the relationship between the surface temperatures of the rolls. As is clear from this, the temperature is at room temperature before the start of rolling, but it increases rapidly until the third roll, and after that, the temperature rises to about 100 pm.
It is stable. In FIGS. 5 and 6, the process until the roll surface temperature stabilizes and the process until the rolling load stabilizes are very similar. The relationship between the lubricant temperature or roll surface temperature and the lubricating effect of rolling oil is explained as follows.

The lubricant is a mixture of rolling oil and water, and the lubricant effect on the contact surface between the rolled material and the work roll is due to the lubricant coming into contact with the hot rolled material and the work roll and turning into rolling oil and water. This is caused by rolling oil that is thermally separated and adheres to the work roll or surface of the rolled material, and it was mentioned earlier in the text that the slipping effect is influenced by the thermal separation of the lubricant. Thermal separation of the lubricant depends on the properties of the rolling oil contained in the lubricant, but if the temperature of the work roll of the rolled material or the lubricant decreases, the thermal separation of the lubricant will decrease, and the lubrication effect will decrease. decreases, the friction coefficient of the contact surface between the work roll and the rolled material increases,
Rolling load increases.

Therefore, by incorporating the temperatures of the rolled material, work rolls, and lubricating oil into the rolling load prediction during setup control, and taking into account the lubricating effect of the lubricant, the rolling load prediction accuracy and plate thickness accuracy at the exit side of the rolling machine can be improved. improves.

For example, the rolling load can be calculated using the following well-known Sims equation [3}
Predict with P.

=kB no R(h, -h2)・Qp......'3'However, Qp=0.80(0.45y+0.04)(noR
/h, -0.5) Po; Rolling load k; Average deformation resistance R; Roll radius h,: Plate thickness at the entrance side of the rolling machine h2; Plate thickness B at the exit side of the rolling machine; = (h, -h2)/h,) Correct the rolling load change due to the variation of the lubricant effect by the temperature To of the rolled material, the temperature T of the lubricant, and the temperature T2 of the work roll using the formula '4}. Ba, P.

'D P〇, f (T small T1 L) ,. ,…,． ,■P
o'; Corrected rolling load prediction value The influence of fluctuations in the lubricating effect of the cross-sectional solvent on the rolling load, which had been ignored in the past, can be incorporated into the rolling load prediction, and T, T, L fluctuated. The rolling load prediction accuracy at the time will be improved significantly.

For example, the formula [4] may be replaced with the formula {5-.

ZP NiP. '/P. ni f (T kou T1・L) = Volume Jitte Jujo .・・・．・・・． ...(5'{4}~t5} formula shows that if the temperature of the rolled material, work roll, and lubricant is high, thermal separation of the rolling oil in the lubricant is promoted, and the rolled material or
This indicates that the rolling load decreases because the amount of rolling oil adhering to the work roll surface increases and the lubrication effect increases.

{An example of actually performing regression analysis based on Equation 51 is zP=f(T.

,T,,T2)! In this case, the influence of ao was extremely small, and it was ZP kosan wool + T2 guard + o-61.

The present invention performs dimensional control using the idea explained above.

Although the following instructions are about setup techniques,
The present invention can be similarly applied to general correction control. FIG. 7 shows a specific example of the present invention. In FIG. 7, reference numeral 1 indicates a rolling mill roll, and 2 indicates a material to be rolled, which is to be rolled by 1. A lubricant is supplied to the contact surface between the roll 1 and the material to be rolled by a lubricant injection device 9. Furthermore, once used lubricant is recovered by a lubricant recovery device 7, purified by a lubricant purification device 8, and reused. 4, 5, 6, 10,
Reference numerals 11, 12, 13, 14, and 15 are setup control devices, which set the roll function of the rolls 1 of the rolling mill so that the thickness of the rolled material 2 after rolling becomes a target value.

First, 101 is a rolling load prediction device that stores the characteristics of the rolling mill and the specifications of the material to be rolled after rolling. Input the thickness h2, and the board B, board thickness h, and temperature To of the rolled material 2 before being coughed into the roll 1 from the board detector 4, board thickness detector 5, and temperature detector 6, respectively. and the above
3}, the rolling load Po when the material to be rolled 2 is forced into the roll 1 is predicted.

12 is a rolling load correction device, which includes a temperature detector 16 that measures the temperature T of the lubricant, 6 that detects the temperature L of the rolled material, and a roll temperature calculation device 13 that calculates the temperature T2 of the roll 1. t, T, , T2 are input, and the rolling load predicted value Po of 10 is corrected using the above-mentioned formula '41 to calculate a more accurate rolling load Po'.

The roll temperature calculation device No. 13 calculates the temperature of the roll, the temperature of the lubricant, the temperature of the material to be rolled, and the heat capacity of each.
Although it can be calculated theoretically using boundary conditions, etc., the following method may also be used.

In other words, if you assume that the roll surface temperature is at room temperature during a long rolling pause or when the rolls are changed, and then store it as a roll surface temperature change pattern as the number of rolled rolls increases, it will correspond to the number of rolled rolls. Once the roll surface temperature is reached, it can be taken out. 14 is the roll opening degree S of roll 1
This is a roll opening calculation device that calculates the predicted value Po' of the rolling load from 12, the spring constant k of the rolling mill, and the target thickness h2 of the rolled material 2 after rolling. It is calculated using

15 is a roll relationship calculation device which inputs the roll function S and sets the roll opening degree of the roll 1 before the roll 1 swallows the material 2 to be rolled.

The above is a specific hardware configuration for reflecting the lubrication effect of the lubricant in actual rolling mill setup control, and by providing such a control device, highly accurate plate thickness control can be achieved.

Further, the present invention can be realized using a general computer instead of using dedicated hardware. FIGS. 8 to 10 show an example using a computer. FIG. 8 is an overall configuration diagram of an embodiment using a computer, and the same reference numerals as above indicate the same parts. Reference numeral 19 in FIG. 8 is a setting device that is set by the operator before starting rolling after changing the o-ru of the rolling mill or after a long rolling stoppage. The setting signal 19 is output to the computer 18, and this setting signal causes the computer 18 to:
In accordance with the procedure shown in FIG. 9, the number N of rolls rolled after changing the rolls and stopping rolling is cleared to 0. When the rolled material 2 in FIG. 8 approaches the rolling mill 1, the material detector 17 inputs a material detection signal to the computer 18. At the timing of receiving this material detection signal, the calculator 18 calculates the roll opening degree S of the rolling mill 1 in order to set the thickness of the rolled material 2 after rolling to the target value, and controls the roll relationship control device 15. Output to. The method of calculating the roll severity S is performed according to the procedure shown in the flowchart of FIG. 10, which was created based on the above-mentioned idea.

The symbols used in the flowchart of FIG. 10 are as follows. 1 constant table K; spring constant R; roll radius A; material property constant B of rolled material; 〃 n; 〃 m; Roll surface temperature TR [2'; Same as above (2nd roll) TR [3} m; Same as above (3rd roll or more) Also; Assumed average strain rate; Load correction constant a for temperature of rolled material; ; Lubricant 〃 a2: Roll surface 〃 h2: Target thickness of rolled material after rolling 2 Variable table N: Number of rolls rolled after roll change and long pause in rolling 3 Other variables B: Inside of rolled material plate h,; Rolled material Rolling machine entrance plate thickness L; rolling machine entrance temperature T of the material to be rolled; lubricant temperature L; roll surface temperature k; average deformation resistance; logarithmic strain Q; rolling force function P for rolling load calculation.

: Predicted rolling load Po'; Predicted rolling load S after correction according to the present invention; Roll relationship In block 105, B, h, , T
o, T, are taken in from each detector (4, 5, 6, 16 in Figure 8), and based on this, the predicted value of the rolling load is calculated in blocks 110, 1 to 15 using the Sims formula, that is, [3] in the text. Calculate by formula.

The block 120 further advances the rolling number N, and the block 120
5,135,140, the roll surface temperature L corresponding to the number of rolls to be rolled is taken out from the constant table TR. block,
Reference numeral 140 is a method for correcting the predicted rolling load value, in which the predicted value of the load is corrected using the formula (2) in the text using the temperature To of the rolled material, the temperature T of the lubricant, and the roll surface temperature T2. block 145
In the main text, calculate the roll function S using the formula 2. At 150, S is the roll opening degree control device 15 in FIG.
Output to. In this way, the present invention can also be realized using a computer. In addition, in the above explanation, only the setting of the roll opening degree was explained, but considering that the plate thickness can also be controlled by tension, correction control during rolling may be performed by adjusting the tension. As explained in detail above,
In the present invention, the influence of the lubricant on rolling is taken into consideration, and the roll opening degree, rolling speed, etc. are set in accordance with the influence, so that highly accurate dimensional control can be realized.

FIG. 11 shows specific data when the present invention is implemented using a computer.

In Figure 1 1, the rolling load is shown on the vertical axis of the number of rolls rolled after changing the rolls on the machine axis. The predicted value of the setup control device (plot marked △ in the figure) and the actual rolling load (plot marked ○ in the figure) are shown.

The actual load of the first roll after changing the rolls was about 1.5 mm compared to the normal rolling load (50 Won) because the surface temperature of the rolls and the temperature of the lubricating oil were low, so the lubricating effect of the lubricant was low, and the rolling load was about 1. Kalon (approx. 77
However, in the method according to the present invention, about 7
It can be seen that the rolling load is predicted to be quite close to the actual load.

As is clear from this figure, the present invention has a particularly remarkable effect on presetting at the initial stage of rolling after a long or relatively long rolling pause. Note that the rolling conditions in the case of FIG. 11 are the same as in the case of FIG.

[Brief explanation of drawings]

Figure 1 is a diagram showing the lubricant drawn between the rolls and the rolled material, Figure 2 is a diagram showing the relationship between the concentration of beef tallow added to the lubricant and the average rolling pressure, and Figure 3 is the aluminum A drawing showing the relationship between the type of lubricant and the amount of roll coating in hot rolling of aluminum, FIGS. 4 and 5 are drawings showing rolling characteristics in hot rolling of aluminum,
FIG. 6 is a drawing showing the relationship between the number of rolls rolled and the roll surface temperature, FIG. 7 is a drawing showing one embodiment of the present invention, and FIGS. 8 to 10 are drawings showing other embodiments of the present invention. FIG. 11 is a diagram showing the rolling load prediction accuracy in the present invention. Explanation of symbols, 1...Roll roll, 2...
・Rolled material, 4...In-plate detector, 5...
・Plate thickness detector, 6...Temperature detector, 8...
...; Garden lubricant purification device, 9...7 Solvent injection device, 10...Rolling load prediction device, 11...
Rolling specification storage device, 12...Rolling load correction device, 1
3...Roll temperature calculation device, 14...
Roll relationship calculation device, 15... Roll opening calculation device, 16... Lubricant temperature detector, 17... Material detector, 18... Calculator, 19... - Operator setting device. Multi-figure hair Z figure hair q figure hair 3 figure 4 Kaya S figure hair et al figure hair `` figure hair 8 figure hair 'o figure hair 11 figure

Claims (1)

[Claims] 1 Control of a rolling mill that obtains rolled products of desired dimensions by inserting material between work rolls, which involves predicting the rolling load during rolling from the temperature and steel type of the material before rolling, The roll opening degree of the work roll is set so that the dimension after rolling of the material is a target value, and the temperature of the material and the temperature of a lubricant that lubricates the contact surface between the material and the work roll are Based on the temperature of the work roll, a correlation that can predict the change in rolling load due to a change in the effect of the lubricant for the steel type is determined in advance, and the correlation that is predicted based on the predetermined relationship is determined in advance. A method for controlling a rolling mill, characterized in that the rolling load of the steel type is used to set or correct the roll opening of the work roll.