JPS5923887B2 - Rolling control method for hot tandem rolling mill - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rolling control method for a hot tandem rolling mill.

In recent years, hot lubrication rolling has attracted attention from the viewpoint of energy saving in the rolling process and improvement of roll consumption.

In this hot lubrication rolling, it is necessary to remove the lubricating oil (hereinafter simply referred to as oil) attached to the rolls in order to stabilize the biting of the tip of the next rolled material and the threading of the rolled material. (Restart oil supply after the rolled material is bitten).

One method for removing this oil is to turn off the oil (stop the oil supply) before the tail end of the rolled material comes off the stand.

At this time, part of the oil adhering to the roll is printed on the rolled material, and another part is removed by being baked at the temperature of the rolled material.

This method has the advantage of not requiring any special equipment to remove oil, but on the other hand, the friction between the rolled material and the rolls increases as the oil is turned on (starting oil supply) or off (stopping oil supply). may change significantly and rolling may become unstable.

For example, if you turn off the oil in a certain stand, the front tension of the stand will decrease significantly, and the rear tension will conversely increase significantly.

This means that the volumetric velocity (mass flow) of the rolled material passing through the oil-off stand has increased.

Of course, loopers or other tension control devices are installed between the stands to correct the width fluctuations that occur due to tension fluctuations, but as the oil level changes become more severe, these tension control devices become less effective. It becomes impossible to follow this mass flow change.

Although only the case where the oil is turned on and off has been described here, similar rolling instability occurs when the oil supply amount is changed significantly.

In view of the drawbacks of the conventional hot lubrication rolling method, the present invention
It is an object of the present invention to provide a rolling method using a hot rolling mill that can perform stable rolling even when the amount of oil is changed significantly (including when the oil is on and off).

According to the present invention, when the oil amount of any stand is significantly changed during rolling, the motor speed of that stand is corrected so as to cancel the mass flow change occurring at that stand.

FIG. 1 shows an embodiment of speed compensation when oil is on and off according to the present invention.

In Fig. 1, 1 is a work roll of a rolling mill, 2 is a backup roll, 3 is a rolled material, 4 is a looper, 5 is a roll drive motor, 6 is a motor speed control device, 7 is an oil supply nozzle, and 8 is an oil Supply system piping, 9 an on/off valve for oil supply, 10 an oil amount adjusting device, and 11 a speed compensator.

The oil amount adjusting device 10 controls oil supply by opening and closing a valve 9.

For example, after a certain period of time after the rolled material is caught in each stand, a valve is turned on to start supplying oil, and a certain period of time before the tail end of the rolled material comes out of that stand, the valve is turned off and oil is supplied. stop.

The oil amount when the valve is on is controlled by a flow rate control valve (not shown), and the flow rate instruction to this flow rate control valve is determined by the oil amount control device 10.

The flow rate instruction value is determined by the steel type of the rolled material, the roll surface condition, etc.

In the present invention, when the oil amount determined by the oil amount adjusting device 10 is turned on and off, speed compensation corresponding to this oil amount is performed.

The speed compensator 11 inputs the pattern determined by the oil amount adjusting device 10 and determines the amount of speed correction associated with the change in oil amount.

FIG. 2 shows an outline of the speed compensator 11.

In FIG. 2, 101 is a valve on/off recognition unit, and 102
103 represents a speed compensation amount calculation unit, 103 represents a speed compensation amount output timing determination unit, and 104 represents an output processing unit.

In the valve on/off recognition unit 101, the oil amount adjusting device 10 shown in FIG.
Input the output valve on/off timing signal and first perform a rationality check.

That is, it is checked whether the timing of turning on or off the valve follows the order of [rolling material biting → valve on → valve off → rolling material tail end falling out].

If the valve on or off signals are in this order, the signals are accepted and a valve on reception signal or a valve off reception signal is generated.

The speed compensation amount calculation unit 102 determines the speed compensation amount when receiving this valve-on or valve-off reception signal.

This speed compensation amount corresponds to the amount of correction of the motor speed necessary to cancel the mass flow change before and after turning the oil on (starting oil supply) or off (stopping oil supply).

FIG. 3 shows the relationship between the amount of change in mass flow and the amount of oil before and after turning the oil on (starting oil supply) or turning it off (stopping oil supply).

This shows an example of data obtained at the first rolling stand.

Rolling is started with no oil supplied at first, and only a certain amount of oil is supplied after rolling reaches a steady state.

At this time, the looper angle changes due to the change in mass flow, but the speed of the first drive motor of the first rolling stand is changed so that the looper angle returns to its original value.

The amount of change in this motor speed corresponds to the amount of change in mass flow,
As shown in Figure 3, the relationship between oil amount and mass flow is determined.

It can be seen that the mass flow change increases as the oil amount increases.

Furthermore, it can be seen that the mass flow decreases when the oil is on, and increases when the oil is off.

Therefore, the output of the speed compensation calculation unit 102 is a speed correction amount that increases the motor speed when the oil is on, and a speed correction amount that reduces the motor speed when the oil is turned off.

Since the magnitude of this correction amount needs to be changed according to the oil amount as seen in FIG. 3, the flow rate instruction determined by the oil amount adjusting device 10 of FIG. 1 or the actual flow rate measurement value is input.

Based on this input value and the output of the valve on/off recognition section (valve on reception signal or valve off reception signal), the speed compensation amount is determined from the relationship shown in FIG.

The timing determining unit 103 determines the timing for outputting the speed compensation amount in consideration of the response delay of the oil supply system.

Normally, oil supply systems have quite large response delays due to pressure loss in the piping and response delays in valves.

Furthermore, there is a delay before the oil sprayed onto the backup roll causes a significant change in the frictional state between the rolling material and the work roll.

For this reason, it is not preferable to immediately issue a speed compensation signal even if a valve-on or valve-off command is issued.

This timing determining section 103 performs a process of delaying the speed compensation signal by a predetermined time after the valve is turned on or off.

This process turns on the oil. A speed compensation signal can be output in accordance with the timing at which a change in mass flow occurs due to turning off.

The output processing section 104 performs output processing of the speed compensation signal.

The speed correction output of the stand where the tail end of the rolled material has come off is immediately cleared by this output processing section.

Therefore, when the tip of the next rolled material bites into each stand, the compensation output is zero.

The speed compensation signal (speed increase) when the valve is on, which has been subjected to the delay processing by the timing determining section 103, is immediately output to the motor speed control device 6 shown in FIG.

Further, the speed compensation signal (deceleration) when the valve is off, which has been subjected to the delay processing by the timing determining unit 103, is added to the speed compensation signal when the valve is on and output.

The reason why the signal when the valve is off is superimposed on the value when the valve is on is that the signal when the valve is off means a speed correction for the speed state before the valve is turned off (the state in which the signal when the valve is on is output). Depends on what you're doing.

According to one embodiment of the present invention, the motor speed can be moved to cancel the mass flow fluctuations at the same timing as the mass flow fluctuations when the oil is on or off, thereby reducing tension fluctuations. , width accuracy is improved.

Here, only examples related to oil on/off times have been described, but similar problems occur when the oil amount is changed significantly during rolling, and stable rolling can be achieved by using the speed compensation method of the present invention. can.

That is, when changing the oil amount in the oil amount adjusting device 10 in the embodiment shown in FIG.

FIG. 4 shows the configuration of the speed compensator.

In FIG. 4, 201 represents a speed compensation determination unit, 202 a speed compensation calculation unit, 203 a timing determination unit, and 204 an output processing unit, among which 203 and 20
4 has exactly the same function as 103 and 104 in FIG.

The speed compensation determination unit 201 performs the following limit check on the flow rate instruction value vavb determined by the oil amount adjustment device 10.

=0 (l vb −Va l <ε)7"(
-vl, -vB (lvb val>g) ε: Predetermined constant Here, ε means a criterion for determining whether a change in oil amount that requires speed compensation has occurred.

In the above equation, if the oil amount change lvb vat is smaller than ε, there is almost no mass flow change ΔV, but if it is larger than ε, a mass flow change occurs according to the absolute value of the difference between Vb and va. means.

The value of ε varies depending on the type of oil and temperature.

The speed compensation calculation unit 202 calculates the speed compensation amount when Δ■\0.

For example, in the case of vb<va (oil amount decrease), read the mass flow change amount ΔV (<0) with respect to va-+vb, as can be seen from the valve-off characteristics in Fig. 3, and convert this to ΔV of the opposite sign.
Let V (=-ΔV) be the motor speed compensation amount.

If vb>va (oil amount increase), ΔV is determined in the same manner based on the relationship when the valve is on.

The timing determining unit 203 performs delay processing on ΔV, and the output processing unit 204 adds the delayed ΔV to the previous output value and outputs it again.

According to this embodiment of the present invention, even when the oil amount during rolling is changed significantly, tension fluctuations due to changes in the oil amount can be suppressed.

As described above, the present invention provides a rolling control method that compensates for tension fluctuations when the oil amount is significantly changed.On the other hand, the speed compensator in the embodiment of the present invention described above There is no need to use system signals or to use speed compensator signals directly in the tension control system.

That is, it can be provided independently of the tension control device.

Therefore, it does not matter what kind of control device is used in the tension control system.

In the previous embodiment, an example using a looper was described, but the present invention can also be applied to a system in which the tension is detected from rolling process data and the motor speed is controlled so that the detected tension matches the target tension. Needless to say.

According to the present invention, when the amount of oil during rolling is changed significantly, it is possible to cancel mass flow fluctuations that occur with the amount of oil, so fluctuations in tension can be suppressed and stable rolling can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing the speed compensator in FIG. 1, and FIG. 3 is a diagram for explaining the relationship between mass flow changes due to oil amount changes , FIG. 4 is a block diagram showing another example of the configuration of the speed compensation device according to the present invention. 1... Work role, 2... Backup role,
4... Looper, 5... Roll drive motor, 6...
・Speed control device, 7... Tuzzle, 8... Oil supply system piping, 9... Valve, 10... Oil amount adjustment device, 11... Speed compensation device, 101... Valve on/off recognition unit , 102・
... Speed compensation calculation section, 103... Timing determination section,
104... Output processing section, 201... Speed compensation determination section, 202... Speed compensation calculation section, 203... Timing determination section, 204... Output processing section.

Claims (1)

[Scope of Claims] 1. In a hot rolling mill that has at least two rolling stands and performs rolling by supplying lubricating oil to the rolling rolls of the rolling stands, during rolling, the speed of the rolling roll drive motor is controlled by the lubricating oil. A rolling control method for a hot tandem rolling mill, characterized in that the rolling control method is corrected according to the amount of change in the supply amount. 2. In the rolling control method according to claim 1, when the supply amount of the lubricating oil increases from the current amount, the speed of the rolling roll drive motor is increased, and the supply amount of the lubricating oil increases from the current amount. 1. A rolling control method for a hot tandem rolling mill, characterized in that the speed of the rolling roll drive motor is controlled to be decreased when the rolling amount is lower than the amount.