JPS5944933B2 - How to control the speed of hotsutran table - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling the speed of a hot run table, and particularly to a method of controlling the speed of a hot run table that is optimal for obtaining a coil with a good winding shape.

FIG. 1 is a schematic diagram of a line from a typical finishing mill to a coiler.

The strip 2 coming out of the finishing mill 1 is conveyed to a hot run table 3 and wound onto a mandrel 6 via pinch rolls 5 and side guides 4 to form a coil 7.

Furthermore, a plurality of hot run cooling devices 8 are provided on the upper surface of the hot run table 3.

In such a hot strip rolling line, conventionally, in order to improve production efficiency, the finishing mill 1 starts accelerated rolling at a predetermined timing from the biting of the strip.

especially. Rolling and winding are performed at high speed in the middle part of the thin strip, but the threadability in the finishing mill at the tail end of the strip, the running performance on the hot run table 3,
In order to ensure a good coil winding shape at the tail end of the strip, the finishing mill 1 and the coiler must be decelerated from high speed to reduce the strip running speed.

Further, after the tail end of the strip leaves the final finishing mill 1, the coiler decelerates and completes the winding process.

Hot run cooling water, side guides 4, pinch rolls 5, hot run table 3, etc. are provided as functions for taking back tension of the strip 2 after the tail end of the strip leaves the finishing and final rolling mill 1.

If these back tensions are insufficient,
During winding, the stripping speed of the mantle increases due to constant tension control, and then begins to slow down.

However, the inertia of the strip 2 at this point is too large, and the strip 2 bulges on the hot run table due to a kind of push-in phenomenon due to the inertia.

As a result, the strip flats induce wide, inner wrap telescopes that are damaged in the coiler front side guides, resulting in large yield silos.

In this way, back tension is very important for maintaining the coiled shape well.

However, if the coiler front side guide is tightened too much, if the board is thin, the coiler front side guide may be damaged and raised.

Furthermore, hot run cooling water is not common because it is regulated by a predetermined winding temperature.

The pinch roll 5 is provided to take back tension, but with the normal pinch roll structure, when the plate thickness becomes thinner, if the pressing force of the upper pinch roll is large, Because it receives thrust force, it is easy to induce telescope, making it difficult to control.

Furthermore, the hot run table 3 is effective in assisting the back tension function of the pinch roll 5 described above, and has been used for some time.

Specifically, it starts decelerating before the tail end of the strip passes through the pre-finishing stage or middle stage stand, and performs rolling deceleration to reduce the running speed of the strip, and the back tension is quite thick. (It is effective.

However, if the hot run table 30 back tension is too large, a negative effect will occur.

In other words, if the tail end of the strip is still being finished rolled, the coiler mantle will lose the back tension of the hot run table 3 and the speed will decrease, causing the strip 2 to form a loop on the exit side of the finishing and final rolling mill 1. Because of this loop, if the vehicle continues to run, the upper header of the hot run cooling system may be damaged and uneven cooling may occur.

Figure 2 shows this situation. On the other hand, if the amount of deceleration at the time when the tail end of the strip leaves the finishing and final rolling mill 1 is small, the strip 2 as shown in FIG.
may be driven directly into the pinch roll 5, and this part is likely to be a telescope of about 1 to 3 turns.

It is also effective to reduce the tension of the coiler mandrel in order to prevent the strip from being pushed when the tail end of the strip passes through the finishing and final rolling mill 1. This reduces the actual winding tension and reduces the looseness of the strip. It tends to become curly.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to provide a method for highly controlling a hot run table that can obtain a good winding shape.

The present invention focuses on the strong back tension of the hot run table, and actively prevents the tail end of the strip from being pushed in when it leaves the final rolling mill and from bulging after that, resulting in good winding. It is designed to obtain the shape.

Here, when the speed of the hot run table is t1, the strip thickness is t1, the strip width is W, and the mandrel tension is T1, the predicted strip speed at the time of final finishing mill removal is V, then a/v=f(t, W ,T) ・・・-”・(1
) can be expressed as

Here, the strip measurement predicted value V can be easily obtained if the speed balance, maximum speed increase, and deceleration rate of the finishing mill are determined.

The reason for setting a/v as shown in equation (1) is that when decelerating the hot run table, the reference for the hot run table is taken from the final rolling mill, so the deceleration is expressed as a ratio to the strip speed rather than as an absolute speed. This is because analog control becomes simpler if

Furthermore, in actual control, the control system can be further simplified by using a method in which several types of representative values are used for a/v and the representative values are selected according to the calculation results.

Examples are 5%, 10%, 25%, 50%.

Setting each deceleration amount to 75% is a value that can be recommended.

These deceleration amounts are 0.95° and 0.90.0 of a/v.
It corresponds to each value of 75.0.50.0.25.

Equation (1) can be empirically expressed as the following equation.

When slowing down the hot run table, it is necessary to determine the timing.

This is because, as mentioned above, if the strip is not decelerated in advance before passing through the finishing and final rolling mill, back tension cannot be effectively obtained due to the elapsed time until reaching A/V, and the third
As shown in the figure, the deceleration phenomenon occurs or the deceleration timing is too early, resulting in a large deceleration amount (as shown in Figure 2), and the deceleration timing is set at multiple points. It is necessary to set it.

The deceleration timing is usually determined from the finish rolling mill's unloading signal (load cell opening/closing signal).If the deceleration starting rolling stand is Fi, then Fi=
It can be expressed as f(v/a, t, w) -- (3).

Equation (3) can be expressed more economically as the following equation, where Fi = 4 ・v/ a-t −W+ and −(4
) (where K, , K, are constants) Fi can be determined by finding V/a in equation (4).

FIG. 4 is a flowchart showing the above-mentioned series of calculation steps.

First, a/v in equation (2) is calculated from each of W, t, v, and T, and the result is 0.4.0.65.0.85.

Compared with preset set points of 0.93 and 0.95,
This is output as a deceleration amount command value, and based on this, a comparison is made with a preset deceleration stand, and the result is output as a deceleration timing setting command.

When the timing is set to 7 points F1 to F7, appropriate patterns for deceleration amounts 5 to 75 are as shown in the table below.

That is, it can be seen that 1 to 35 appropriate patterns can be selected as shown in the above table.

In this way, the hot run table speed can be changed based on the strip size, the speed of J-tube removal, etc., an appropriate back tension can be obtained, and a well-wound coil can be obtained.

According to the present invention, the following effects can be obtained.

(1) The coil winding shape is improved by stabilizing the running properties of the hot run table at the tail end of the strip, that is, the yield and production efficiency are improved by reducing winding defects in the next process.

(2) As the running performance of the hot run table at the tail end of the strip is stabilized, the maximum finish rolling speed can be increased, that is, production efficiency can be improved.

(3) Operational stability can be achieved through automatic control.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a line from a general finishing mill to a coiler, Fig. 2 is an explanatory diagram showing the occurrence of a loop in the strip, Fig. 3 is an explanatory diagram showing the occurrence of a telescope in the strip, and Fig. 4 is an explanatory diagram showing the occurrence of a strip loop. is a calculation flowchart of the present invention. 1... Finishing rolling mill, 2... Strip, 3... Hot run table, 4... Side guide, 5... Pinch roll, 6... Mandrel, 7... Coil, 8
...Hot run cooling device.

Claims (1)

[Claims] 1. In a line where the strip exiting the finishing mill is wound onto a coiler via a hot run table and a pinch roll, when the tail end of the strip is located on the surface of the hot run table, the hot run table is A hot run table characterized in that the deceleration timing and the amount of deceleration are changed based on the thickness of the strip, the width of the strip, the winding tension, and the predicted speed of the strip when it exits the finishing mill. Speed control method.