JPH0299210A - Method for shape control for sheet rolling - Google Patents

Abstract

PURPOSE:To improve controllability for sheet shapes by finding a changed thermal crown amount based on deviation of a present shape signal from a shape detector and a target shape signal at n-many partitioned positions on the outlet side of a rolling mill and obtaining a necessary coolant flow rate by on-off control of spraying. CONSTITUTION:A coolant is sprayed onto a work roll 1 from n-many partitioned spray nozzles 2 in the longitudinal direction for a work roll 1. A changed thermal crown amount eliminating deviation between a present shape signal and a target shape signal from a shape detector 3 for sheet shapes at respective n-many partitioned positions set on the outlet side of a rolling mill is obtained and a necessary coolant flow rate is obtained by on-off control. An equipment is less expensive because the necessary coolant flow rate is controlled by on-off control per unit period of time without analogue control and by only an on-off valve. An accurate coolant flow rate is obtained because the on-off ratio for a unit period of time and a flow rate indicate linearity. Hence, the equipment cost is reduced and the controllability for sheet shapes is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the shape of a copper plate or the like during rolling of the plate.

[Conventional technology]

This kind of plate shape is an extremely important element in terms of quality control, and in the case of electrical steel sheets in particular, the current situation is that strict control of the plate shape is required because thin plates are stacked together and used in transformers. In addition, the plate shape has a significant impact on product yield and workability in downstream processes.

In general, shape defects such as edge elongation, one-sided elongation, and mid-elongation are caused by uneven thickness distribution of the material to be rolled, deflection of the rolling rolls, thermal expansion, and the like.

Conventionally, sheet shape control has been carried out exclusively by using means such as intermediate roll benders, work roll benders, and work roll benders by displacing intermediate rolls in the sheet width direction in order to mechanically adjust the bending, deflection, or crown of the rolls. It's here. However, this type of means is used exclusively to control edge elongation and mid-elongation, and the ability to control shape is small for so-called compound elongation and local elongation in which these elongations coexist simultaneously.

Therefore, in recent years, a method of projecting coolant onto a work roll and controlling the flow rate of the coolant has been used to deal with compound elongation and local elongation, and this method plays a major role in improving the plate shape.

For example, JP 55-421615, JP 55-81
No. 010, No. 59-16608, No. 60-15890
Techniques such as Publication No. 9 can be mentioned.

[Problem to be solved by the invention]

However, the techniques disclosed in each of the above-mentioned publications obtain the coolant flow rate for obtaining a desired thermal crown by controlling in an analog manner the valve angle of a flow rate regulating valve provided in a coolant supply pipe to an injection nozzle.

However, providing a flow 41 regulating valve and a flow rate regulator (including a flow meter) for each injection nozzle line increases equipment costs.

Moreover, controlling the coolant flow rate in an analog manner inherently has poor controllability. That is, as shown in FIG. 6, what is the opening degree of the flow rate regulating valve and the flow rate?

This is because there is a certain opening range that is nonlinear and exhibits rapid changes in flow rate.

Therefore, the main object of the present invention is to provide a plate shape control method that reduces equipment costs and provides excellent plate shape controllability.

[Means to solve the problem]

The above problem is solved in a method of controlling the plate shape while projecting coolant from injection nozzles divided into n parts in the longitudinal direction of the work roll; Based on the deviation between the current shape signal at each division position from the shape detector that detects the plate shape and the target shape value, the amount of changed thermal crown at each division position of the roll to eliminate this deviation is determined, and this change is made. This problem can be solved by obtaining the coolant flow rate required for the thermal crown amount by non-off control of coolant injection from each injection nozzle per unit time.

[For production]

In the present invention, the coolant flow rate required to change the thermal crown is not controlled analogously, but is controlled on/off per unit time.
Simply using an on/off valve is sufficient, reducing equipment costs. Moreover, as shown in Fig. 5, the on/off ratio per unit time and the flow rate show linearity, so by controlling the on/off ratio, it is possible to obtain the accurate required coolant flow rate. Improves controllability of plate shape.

[Specific structure of the invention]

The present invention will be explained in more detail below.

FIG. 1 shows a control system according to the present invention, in which when material M is passed through a rolling mill S, it is controlled to have a desired thickness and shape. Coolant injection nozzles 2 are divided into n pieces in the longitudinal direction of the work roll 1.1 of the rolling mill S.
Coolant (oil) is projected from 2... Further, a shape detector 3 is provided on the exit side of the rolling mill S, and is configured to obtain at least n strip shape signals in the strip width direction. A general-purpose product can be used as this type of shape detector 3.

Here, there are n coolant injection nozzles and n shape detectors.
However, in the present invention, the number of divisions of the shape detector does not necessarily have to be n.

For example, if the number of divisions of the shape detector is 2n, the adjacent 2
The signals from the detectors can be averaged, for example, and used to control the coolant flow rate from the corresponding injection nozzle, and the number of detector divisions can be reduced to, for example, n/2.
It is also possible to estimate the plate shape as a whole using the shape signals from each division position, and use the estimated value for plate shape control.

Based on the shape signals for each of the n divided positions from the shape detector 3, each injection nozzle 2,
2. On/off of coolant injection from... II?
Wholesaling is done.

That is, the shape output Δε1 at each position of the n shape detectors 3 arranged in the width direction, and the change amount Δh of the exit side plate thickness in each width direction from the n shape target values Δε□ in the width direction are calculated using the following formula. Find it at

h-1-h,, (1+ΔL□) ... (1) h-1
= hJ1) (1+Δ!l J, l) ... (2)
Δh,=h14. l-h,, 4 (1) to (5) From the second... (5) ...... (6) However, h: Output side reference plate thickness (center value of plate thickness control) h8. : Target plate thickness on the exit side of width direction n zone hJn Actual plate thickness on the exit side of n zone l : Standard length from work roll center to shape detector Δ10 : Target plate elongation amount from work roll center to shape detector ΔlJn :Actual temporary elongation amount from the work roll center to the shape detector Next, from this outlet side plate thickness change amount Δh7, the rolling position change amount ΔS7 at each division position between the upper and lower rolls is calculated as follows (7
)2.

(Q - plasticity coefficient M: mill constant) Next, the roll diameter change amount ΔRn at each division position is determined from the rolling position change amount ΔSn.

ΔR,=ΔS7/2 (8) Here, the roll diameter change amount ΔR7 is given by the roll thermal expansion amount u(r) due to cooling and heating up of the roll coolant.

Therefore, it is calculated using the formula below, which is often used.

Here, β: coefficient of thermal expansion, C: Boisson's ratio, r: roll radius, Δ lower,: average temperature change in the cross section of the roll.Also, the approximation of equation (9) can be obtained by substituting r=R. , T,: coolant temperature, C,: coolant concentration,
α: Calculate the required coolant flow rate Qn at each division position as the heat transfer coefficient.

Further, when the maximum coolant flow capacity per unit time from a certain injection nozzle is Q m m x, the on (open) time ratio T7 per unit time of the on-off valve of the injection nozzle system is determined by the 0-turbidity formula.

−(1+ν)βΔTRR...0ω The amount of roll thermal expansion can be determined as the amount of temperature change.

The temperature change amount ΔTRn thus obtained is classified as follows depending on whether it is positive or negative.

1) When Δ lower π is negative (when trying to lower the roll temperature) Q, = f, (ΔTR1l, T, , C,, α)・U12)
When ΔT□ is positive (when attempting to raise the roll temperature), either set T, at the division position to zero (turn off the on-off valve), or reduce T,. Note that the response is faster if the on-off valve continues to be closed.

The T7 can also be expressed as an on/off ratio (r) of the 041 formula, as shown in FIGS. 2 and 3.

In practice, it is preferable to control T1 determined in this way, for example, by the following method.

First, the past unit time (for example, 30
Record the actual opening/closing pattern for each division position (seconds).

Next, the following (
In consideration of (a) to (d), it is preferable to determine the output Bakun in the future unit time using the example in FIG. 4 and the methods (a) to (dl) described below.

(B) Coolant valve opening/closing should be kept open and closed for at least 3 seconds (mechanical constraints) (B) No more than 10 valves can be opened and closed at the same time (mechanical constraints) (c) Rolling speed All are closed below a certain level (coolant constraint condition) (d) Maximum number of open units is 20 (flow stability constraint condition) fa)
The expected output value is determined by (target % value - past unit time performance %), and is set in order from the largest value.

(bl) Items with the same planned percentage value are set in order of decreasing actual percentage value.

(C) The simultaneous opening/closing limit of up to 10 valves is set from Q on the time axis, and zones with 10 or more valves are distributed to areas where there is less overlap in valve ON.

(d) Do not set a pattern for items whose planned percentage value is negative.

In FIG. 4, the number of coolant valves is 7, and the maximum number of valves that can be opened simultaneously is 3.

An apparatus for carrying out the above procedure is shown in FIG.

〔Example〕

(Example 1) In order to confirm the effect of this control method, we cut off this control midway and recorded the steel plate shape at 10 second intervals during this control and in the process of the control section, and the results shown in Fig. 7 were obtained. Obtained.

From the results shown in the figure, the plate shape is improved by the start and progress of this control, becoming a smooth medium elongation shape as shown in shape pattern ■, and when the main control is turned off, it becomes quarter elongated as shown in shape pattern ■. It can be seen that when this control is performed again, it recovers to a smooth, medium-elongated shape as shown in shape pattern (3). Therefore, it is clear that the present control method is extremely effective in improving the plate shape.

In addition, IUNit in the same figure means that when the elongation length per unit length β is bl, the elongation rate difference = Δl/l is 105
It is doubled. Therefore, θ5) Formula % Formula % Also, there is a relationship between the steepness and the formula 00.

(Example 2) In plate rolling of a copper plate with a thickness of 0.5 xx x width of 1000 mm, conventional analog control cannot control the steepness (
h/j') was 0.8%, whereas according to the method of the present invention, the steepness was 0.4%, and it was recognized that the controllability of the plate shape was improved.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce the equipment cost required for control, and the controllability of the plate shape is improved.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the control system for implementing the method of the present invention, Figs. 2 and 3 are explanatory diagrams of the on/off ratio, Fig. 4 is an explanatory diagram of the order of setting output patterns, and Fig. 5 6 is a flow rate characteristic diagram based on the on/off ratio according to the present invention, FIG. 6 is a flow rate characteristic diagram using a conventional flow rate regulating valve, and FIG. 7 is a diagram showing changes over time in the plate shape pattern as a result of control according to the method of the present invention. M...Material, S...Rolling machine, 1...Work roll, 2...Injection nozzle, 3...Shape detector (r=33%) ml Diagram (r: 10O10) Jiang Bindai Diagram 100% 〉/Off ratio (r) Diagram ○ 100% Full opening degree

Claims (1)

[Claims] (1) In a method of controlling the plate shape while projecting coolant from spray nozzles divided into n pieces in the longitudinal direction of the work roll; Based on the deviation between the current shape signal at each division position from the shape detector that detects the shape and the shape target value, the amount of modified thermal crown at each division position of the roll to eliminate this deviation is determined, and this modified thermal A shape control method in plate rolling, characterized in that the coolant flow rate required for the crown amount is obtained by on/off control of coolant injection from each injection nozzle per unit time.