JPH0228402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rolling apparatus for extracting rolled material from a heating furnace and rolling it.

Figure 1 shows a conventional hot thin plate rolling apparatus, in which 1 is a heating furnace, 2 is an extractor for extracting rolled material from the heating furnace 1,
3a to 3d are rough rolling mills, 4a to 4d are hard rolling mills,
5a to 5f are finishing rolling mills, 6a to 6c are winding machines that wind up the rolled material rolled by the finishing rolling mills 5a to 5f, and 7a and 7b are finishing rolling mills 5a to 5f, conveyance table 25, and rough rolling mill 3a. 3d and a control device for a motor that drives the hard rolling mills 4a to 4d, 8 a rolling schedule calculation device, 10 a scale breaker, and 11 a winding device that drives and controls the winding machines 6a to 6c that wind the rolled material. A extractor control device 12 is an extractor control device that controls the extractor 1.

Further, FIG. 2 shows a conventional thick plate rolling machine for rolling thick plates, where the same reference numerals as in FIG. 1 indicate the same or corresponding parts, 13 is a rough plate rolling machine, 15 is a finishing plate rolling machine, Each rolling mill in these conventional hot thin plate rolling equipment and thick plate rolling equipment has a roll opening degree during rolling, roll rotation speed, number of rolling passes of the reversible rolling mill, roll rotation speed during biting, and A rolling schedule that sets the roll rotation speed at an appropriate value during release is calculated by the computer 8, and the control devices 7a and 7b control the rolling mill and the conveying tables 25 before and after the rolling mill for each rolling pass. .

At this time, conventionally, in order to determine the rolling schedule, the schedule that allows rolling for the shortest time with the minimum number of passes has been selected.

In a rolling mill, if the rolling temperature T, the rolling speed N, the inlet side plate thickness H, the outlet side plate thickness h, and the inlet side plate width W are given, a predetermined rolling force can be calculated from the diameter R of the rolling mill roll and the constant M of the rolling mill. F, predetermined power PW, and roll opening degree S are determined.

F=f ₁ (H, h, T, N, R, W) (1) PW=f ₂ (H, h, F, R) (2) S=f ₃ (h, F, M) (3) Here, the maximum rolling force, maximum power, and maximum rolling amount are determined based on the characteristics of each rolling mill, so if you decide the schedule for each rolling pass with the maximum power in each rolling mill as the goal, you can minimize the number of passes and minimize the number of passes. Time rolling becomes possible.

For example, the rolling schedule is calculated by the rolling schedule calculation device 8 as follows. The rolling specifications of the rolled material are input to the rolling schedule calculation device 8 for each rolled material. Specifically, the dimensions of the rolled material, that is, the slab, the slab temperature, the material, the target dimensions after rough rolling, the final coil dimensions after finish rolling, the finish exit temperature, the rolling speed of the final stand, and the load distribution of each rolling mill. The ratio is given. On the other hand, equipment specifications for each rolling mill are determined in advance. These are the work roll diameter of the rolling mill, the maximum rolling speed, the rolling force limit, the rolling power limit, and the maximum rolling amount.

Based on the specifications given above, calculations are performed as follows. Rough rolling mills 3a to 3d and finishing rolling mill 5
Schedule calculations are performed separately for a to 5f. The rough rolling mills 3a to 3d are given power-thickness curves for the rough rolling mills 3a to 3d. This is called a power curve. This is expressed by the following formula.

PW=f ₁₀ (h, h ₀ , W ₀ , k ₅ ) (4) PW: Cumulative value of rolling power h: Target plate thickness h ₀ : Initial plate thickness W ₀ : Initial plate width k ₅ : Material type This is shown in the figure. If expressed as shown in FIG. 5, 40 is the power curve.

Now, given the inlet plate thickness h ₀ of the rough rolling mills 3a to 3d and the outlet plate thickness h _r of the rough rolling mills 3a to 3d, the cumulative power PW _r required for rough rolling is determined from the power curve. Once this cumulative power PW _r is determined, this power distribution is given to α ₁ , α ₂ , α ₃ , α ₄ and each rough rolling mill 3a to _3d . If you assign it to 3a to 3d as shown in Figure 5,
The outlet plate thickness of each rough rolling mill 3a to 3d can be determined.
Therefore, the inlet and outlet plate thicknesses of the rough rolling mills 3a to 3d are determined.

Next, since the rolling speed of each rough rolling mill 3a to 3d is given, the time required for the material to reach each rough rolling mill 3a to 3d is determined. This can be calculated because the operating speed pattern of the conveyance table is fixed and only the speed during rolling is synchronized with the rolling speed.

If the transfer time is known, the material temperature will drop due to radiant heat during that time. Tout = f (Tin, H, Cp, γ, t) Tout: Output temperature Tin: Inlet temperature H: Plate thickness Cp: Material specific heat γ: Material density t: Obtained from radiant heat. Therefore, the rolling temperature can be predicted, and once the rolling temperature is determined, each value on the right side of Equation 1 is known, so the rolling force F is determined, and the roll opening degree is determined from Equation 3 thereafter. Once the rolling schedule for the thickness is determined, the width rolling schedule for the hard rolling mills 4a to 4d can then be calculated.

If the slab width and the target width on the rough side are given now, the amount of expansion in the width direction due to each pass rolling can be calculated using the following formula.

ΔWi=f ₂₀ (Hi, hi, Wi, Ei, Ti, Di) ΔWi: Width expansion Hi: Inlet side plate thickness hi: Outlet side plate thickness Wi: Hard rolling mill entrance side plate width Ei: Hard rolling mill rolling reduction amount Ti: Rolling temperature Di: Work roll diameter Therefore, the total width reduction in rough rolling is given by the following formula.

BR=W ₀ −W _r + _N 〓 ⁱ⁼¹ ΔWi BR: Rough rolling total width reduction amount W ₀ : Slab width W _r : Rough target width N: Number of rough rolling passes Width reduction distribution that gives this total width reduction amount By assigning the ratio to each hard rolling mill 4a to 4d, the rolling reduction amount of the hard rolling mills 4a to 4d is determined. Once the rolling reduction amount is determined, the rolling force and opening degree can be determined using the same formula as for horizontal rolling.

Since the finishing rolling mills 5a to 5f are continuous rolling machines,
Since the final plate thickness and the speed of the final finishing rolling mill 5f are given, they can be determined by determining the plate thickness of each rolling mill 5a to 5f according to the law of constant volume. That is, hi·Vi=hf·Vf hi: i Rolling machine outlet side plate thickness Vi: i Rolling machine rolling speed hf: Finished plate exit side plate thickness Vf: Finishing final rolling machine speed. Therefore, it is sufficient to find the rolling pattern.

Similar to rough rolling, this rolling pattern is determined from the power curve by giving the finishing input side plate thickness, finished finishing plate thickness, and the load distribution ratio of each rolling mill.

Therefore, the speed is determined, and once the speed is determined, the rolling temperature can be calculated from the time of arrival at the rolling mill.Next, the rolling force is determined, the rolling position of each rolling mill is determined, and the schedule calculation is completed.

Based on this schedule calculation, rolling conditions are set from the rolling schedule calculating device 8 to the control devices 7a and 7b, and the rolled material taken out from the heating furnace is rough rolled and finish rolled as described above.

However, in the finishing mills 5a to 5f, 15, the rolling pass schedule is usually determined based on the plate finish crown value, etc., rather than performing rolling for the shortest time. This means that reversible rolling is not performed in finish rolling, and for thick plates, one rolling mill performs only one final pass, or for thin plates, several rolling mills are used in sequence to complete the rolling process. This is because the rolling time is determined by the length of the material and the amount of reduction in plate thickness due to rolling. For this reason, no advantage can be found even if the rolling schedule is calculated with the goal of the shortest rolling time.
There is also a method of determining the rolling schedule with the goal of finishing accuracy and product quality accuracy.

In any case, these rolling schedules are determined based on the specification limits of the rolling mill, such as rolling power, etc.
Naturally, calculations have been made to satisfy the rolling force, but in the past, the thermal load on the rolling mill motor was not taken into account.

This is because even if the thermal load on the rolling mill motor temporarily exceeds the specification limit by, for example, 10%, it does not directly cause a motor failure at that point.

However, if the heat load continues to be excessive, the insulation performance of the rolling mill motor will deteriorate.
This will lead to malfunction.

This invention was made in consideration of these points, and it prevents the overheating state from continuing.
It is an object of the present invention to provide a rolling device in which the rolling mill motor is always controlled in an appropriate state.

In the rolling mill according to the present invention, the thermal load on the rolling mill motor is monitored and determined by the monitoring device, and the extraction pitch of the extractor is controlled based on the result of this monitoring and determination, so that even if the thermal load on the rolling mill motor is temporarily reduced, Even if the permissible value is exceeded, the heat load is reduced in subsequent rolling, so the over heat load does not continue and the rolling mill motor can be operated in an appropriate state.

A hot rolling apparatus as an embodiment of the present invention shown in FIG. 3 will be described below. In Figure 3,
Since the same reference numerals as in FIG. 1 indicate the same or corresponding parts, the explanation thereof will be omitted. 9a to 9e are rough rolling mills 3
A rolling mill motor 20 drives the rolling mills a to 3d and finishing rolling mills 5a to 5f, and 20 is a monitoring control device that monitors the heat load state.

Next, the operation will be explained. After the rolled material is heated to a predetermined temperature in the heating furnace 1, it is taken out onto the conveying table 25 by the extractor 2, passes through the scale breaker 10, and is sent to hard rolling mills 4a to 4d and rough rolling mills 3a to 3d. After the sheet is rolled to a predetermined thickness, it is rolled to the final thickness in finishing rolling devices 5a to 5f. This rolled material is coil winding machine 6a~
It is wound into a coil with 6c.

By the way, the thermal load state of the rolling mill motor 9 is expressed by the ratio of the rated current value to the root mean square value of the current of the rolling mill motor 9. The ratio of the current root mean square value is expressed by the following 5 formulas.

However, RMSi=ratio of the root mean square value of current of rolling mill motor i; Ii=instantaneous current value of rolling mill motor i _{; 0} i=rated current value of rolling mill motor i; τ=monitoring time. As is clear from Equation 5, if the monitoring time τ is constant, the ratio of the current root mean square value RMSi
It can be seen that in order to decrease the current Ii of the rolling mill motor, it is sufficient to decrease the current Ii. Therefore, since it is sufficient to reduce the load on the rolling mill motor, it is sufficient to extend the time during which rolling is not performed.

By the way, in order to make maximum use of the capacity of the rolling line, it is desirable to perform rolling one after another on the rolling line without collision between the previous rolled material and the next rolled material. However, this is contradictory to lowering the root mean square of the current. In such a state, the current of one rolling mill shows changes as shown in FIG. In the figure, 30 indicates a current change curve, 32 indicates rolling, 31 indicates non-rolling, and 33 indicates stop.

In FIG. 4, when the thermal load on the rolling motor is excessive, it is sufficient to reduce the ratio of the root mean square of the current, and therefore it is sufficient to lengthen the non-rolling time 31. In other words, when extracting the rolled material from the heating furnace 1, it is sufficient to make the extraction pitch longer.

Therefore, the extraction pitch is monitored by the rolling mill motor 9a.
It is only necessary to obtain the RMSi values of ~9d from Equation 5 and determine them all to be within the ratio RMS ₀ i of the root mean square value of the allowable current.

Now, if τ in Equation 5 is the time from the start of rolling of one material to the start of rolling of the next material in each rolling mill, the amount of correction of the extraction pitch determined from the point of heat load is given by the following equation.

ΔPit(i)＝∫t ^t+ 〓 ⁱ Ii ² dt／(RMS ₀ i) ² × (I ₀ i) ² −τi
(6) RMS ₀ i = Ratio of allowable maximum current root mean square value of i rolling mill motor τi = Time from the start of rolling of the rolling mill to the start of rolling of the next material Here, the first term on the right side of equation 6 is the rated current I ₀ It means the rolling time assuming that motor i is used to roll up to the maximum allowable root mean square current limit,
The entire equation 6 means the difference between the required rolling time when the motor is used up to its thermal limit (the limit of the maximum allowable current root mean square value) and the actual rolling time (τi). Therefore, the maximum correction amount (ΔPit(i)) of each rolling mill motor 9 is taken as the pitch correction amount extracted from the heat load, and other factors (for example, collision prevention between materials on the line, The next material extraction pitch is determined by adding this extraction pitch correction amount to the extraction pitch calculation value of the next rolled material to be extracted from the heating furnace 1.

In other words, the thermal load monitoring device for the rolling mill motor measures the current value of each rolling mill at regular intervals and issues a command to the extractor control device. For monitoring, each time each rolling mill starts rolling, the root mean square value of the current from the previous start of rolling is determined and checked. After checking, the extraction pitch correction amount is determined and the current extraction pitch is corrected.

In the above embodiment, a hot thin plate rolling mill was described, but the same method can be applied to the thick plate rolling mill shown in FIG.

It is also effective to check the root mean square value of the current at regular intervals, for example every 20 minutes, instead of checking it every time rolling starts.

As described above, according to the present invention, the heat load state of the rolling mill motor is monitored and the extraction pitch of the rolling mill is controlled based on the result of this monitoring, so that the rolling mill motor can be used in an appropriate state. This has the effect of extending the life of the rolling mill motor.

[Brief explanation of drawings]

Figures 1 and 2 are block diagrams showing conventional hot thin plate rolling equipment and thick plate rolling equipment, Figure 3 is a diagram showing the configuration of an embodiment of the present invention, and Figure 4 shows changes in the current of the rolling mill motor. The current change curve shown in FIG. 5 is a curve diagram showing plate thickness versus required movement. In the figure, 1 is a heating furnace, 2 is an extractor, 3a-
3d is a rough rolling mill, 4a-4d are hard rolling mills, 5a-
5f is a finishing rolling machine, 6a to 6c are winding machines, and 7a to 6c are winding machines.
7b is a rolling mill and motor control device; 8 is a rolling schedule calculation setting machine; 9a to 9e are rolling mill motors; 20 is a rolling mill motor heat load monitoring device;
21 is a control device for the extractor, and 22 is a control device for the winder. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A rolled material taken out from a heating furnace by an extractor is rolled in a rough rolling mill according to each extraction pitch calculated in advance, and then formed into a predetermined thickness by a finishing mill. In this case, the extraction pitch correction amount ΔPit(i) is calculated based on the ratio of the root mean square value of each rolling mill motor to the root mean square value of each allowable current at a predetermined monitoring time τi. ∫t ^t+ 〓 ⁱ I ² idt/(RMSoi) ² ×I ² oi−τi However, ∫ ^t+ 〓 ⁱ _t I ² idt is the root mean square value of the current of each rolling mill motor, and RMSoi is the allowable current square of each rolling mill motor. As the ratio between the average value and the rated current Ioi, the correction amount ΔPit(i) of each of the above extraction pitches
A rolling method characterized in that the maximum value among these values is added to the pitch calculation value of the next rolled material to be carried out to determine the next material extraction pitch.