JPS59183915A - Method for setting roll gap of hydraulic rolling-down type rolling mill - Google Patents

Abstract

PURPOSE:To improve the accuracy in controlling the thickness at the front end of a steel plate and to prevent generation of a defective part in the thickness in the stage of gnawing in correcting the compressing rate of an oil colum by putting the actual height of the oil column to the correction data and calculating the rate of correction. CONSTITUTION:A detector 13 for the height of an oil column which detects electrically the height of the oil column is provided to a hydraulic cylinder 5 and the output signal from the detector 13 and the output signal from a screw position detector 9 are transmitted to a control device 14 for rolling-down position. A servocontrol valve 10 is controlled by the rate of correcting compression of the coil column calculated by the device 14. On the other hand, the signal corresponding to rolling load is transmitted from a load detector 4 to a process computer 15. The impact load in the stage of gnawing is predicted by the computer 15 and the roll gap of the device 14 is set at a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roll opening setting method for a rolling mill that uses a hydraulic rolling device to control the rolling position of the rolling mill.

In a rolling mill equipped with a hydraulic reduction device, when rolling a steel plate,
At the time of biting, the average load is approximately 1.3 as shown in Figure 1.
A double impact load is generated, and the oil in the hydraulic cylinder that makes up the hydraulic pressure reduction device is instantly compressed. In order to respond to these instantaneous changes, there are systems that completely control the oil column in a fixed position, but the hydraulic cylinder is unable to keep up with this.

For this reason, the rolling of the tip of the steel plate progresses before the rolling position corresponding to the desired plate thickness is reached, resulting in the inconvenience that only the tip of the steel plate becomes thicker, as shown in FIG.

In order to solve this inconvenience, conventionally, a correction means has been adopted in which the position of the hydraulic cylinder is set in advance to be small only when the plate is engaged.

This is done by experimentally determining the rolling pressure and oil column compression at the time of biting from actual rolling data as shown in Figure 3, and then calculating the impact load at the time of biting from the rolling load calculated by a process computer, etc. , the roll opening degree is set small by the amount of oil column compression from Fig. 3, and △ seconds (empirically, about 0. 05
A method is adopted in which the amount of correction is canceled after 2 seconds). However, if the pressure acting on a compressible fluid such as oil changes by ΔP,
The amount of change in the volume V, △V, is expressed as follows, assuming that the compressibility of oil is β:
As shown in equation (1), it changes depending on the volume of oil in the hydraulic cylinder.

△V (I) - β (Jishun) × △P (kg/n?) X
V (rn')... (1) In this way, the amount of oil compression is also related to the volume, and in particular, in thick plate rolling, etc., the roll opening changes as the thickness of the rolled material changes, The amount of oil column changes by nearly 10n.

This amount of oil column change corresponds to about 0.2 dragon when converted into compression amount.

The amount of oil column compression can be determined by the impact load and the oil column height, but in the past, the oil column height was fixed and the correction was made, so the correction was not made completely and the plate thickness Some thick or thin parts remained.

An object of the present invention is to provide a method for setting the roll opening degree of a hydraulic reduction type rolling mill that eliminates the above-mentioned conventional drawbacks by preventing the formation of a thickness defective portion at the tip of a steel plate when the steel plate is bitten. .

In the oil column compression amount correction for setting the roll opening before rolling, the actual oil column height is included in this correction data to calculate the correction amount, thereby improving the control accuracy of the copper plate tip thickness. This is what I did.

FIG. 4 is a block diagram showing one embodiment of the present invention, which includes work rolls 2A and 2B that roll a steel plate 1, two work rolls, and a backup roll 3 that backs up all of 2B.
A rolling mill is constituted by A, 3B, and rolling devices such as a hydraulic cylinder 5, a rolling motor 6, and a rolling screw 7 for adjusting the rolling 1 position of the rolling mill. Further, the hydraulic cylinder 5 is controlled by a servo valve 10 that completely controls the oil in the cylinder, and the servo valve 10 is supplied with oil in an oil tank 11 by a hydraulic cylinder 12. Further, the hydraulic cylinder 5 is provided with an oil column height detector 13 that pneumatically detects the oil column height fcN, and the output signal of this detector 13 and the output signal of the screw position detector 9 are controlled by the pressure 1 position control. It is sent to the device 14, and this lowering position control device 14
Turbo valve 10 according to the oil column compression correction amount calculated by
is controlled. On the other hand, the load detector 4 sends a signal equivalent to the rolling load to the process computer 15, which predicts the impact load at the time of biting and sets the roll opening degree of the rolling position control device 14 to a predetermined value.

Various types of oil column height detector 13 can be considered, but for example, as shown in FIG. A magnetic detection head 52 is fixedly installed facing the magnetic surface of the metal rod 51 so that an electric signal corresponding to the movement of the metal rod 51 can be obtained. The total height of the oil column is detected by counting with the counter 53. The detection accuracy is determined by the precision of the metal rod itself, but it is possible up to 2 μm units. Note that the metal rod 51 side may be fixed and moved in accordance with the total oil column height on the magnetic detection head 52 side.

In the above configuration, when rolling the steel plate 1, the oil in the hydraulic cylinder is compressed when the steel plate 1 is bitten by the work rolls 2A, 2B, and the height of the oil column is momentarily reduced.
The roll opening will open (this phenomenon is instantaneous,
(At this point, the control of the roll opening degree cannot follow the flow.) However, since the oil column height is controlled in position by the detection force of the oil column height detector 13, it gradually returns to the original state. This oil column compression amount Δl is expressed by Equation (2), which is a modification of Equation (1).

Δ1(rn)-β(l/kg)×ΔP (k!?) X
l (m,)(',' V (m')=D CmsuX
l(m)) ・=・ = (2) However, △P:
Biting impact load l: oil column height D cylinder cross-sectional area Δl' of formula (2) is predicted, and the process computer 15 and the roll-down position control device control the roll opening degree to be set small in advance when setting the roll-down position. 14th! ll Execute according to the flowchart in FIG.

First, in order to obtain the target exit side plate thickness H using the process computer 15, the third
), the target roll opening degree S is determined, the servo valve 10 is driven, and the position is set so that the roll opening degree becomes S.

5=H--・・・・・・・・・・・・・・・・・・
...... (3) 4 However, F: Predicted average load (kg) M: Mill tonality constant (kg/proverb) Next, the biting impact load △P is expressed as (
4) Obtain from the formula.

ΔP (kg) = αX F (k!?)...
・・・・・・・・・・・・・・・(4) However, α:
Biting impact coefficient (approx. 1.3 empirically) Further, the oil column compression amount ΔJik is determined using equation (2). The oil column height l used in equation (2) is detected by an oil column height detector 13. △J calculated using this equation (2)
Deviation (S-Δ)i) between i and S calculated by equation (3)
is reset as the target roll opening degree S'. This resetting changes the oil column height l, so the oil column compression amount Δ in equation (2) is
! is calculated again to obtain the oil column compression amount ΔJH-t. This Δ
li+1 was subtracted from the target roll opening degree S' (S-
ΔA! i+1) is reset as the target roll opening degree S''.The above operation is repeatedly performed until equation (5) is satisfied.

1ΔLi+1−Δljl<C・・・・・・・・・・・・
...(5) However, C is the convergence completion determination deviation amount (for example, after 10 or more processes are completed, steel plate 1 is bitten in the rolling mill, and Δ is set in seconds from the time of biting detection (empirically, about 0 .05 seconds) then Δllk') is set. Through the above operations, it becomes possible to control the thickness of the steel plate so that the tip thickness of the steel plate is also made flat.

For example, in the past, there was a thick part at the biting tip as shown in Figure 7 (a), but with the application of the present invention,
The entire surface could be made flat as shown in Figure (b).

As is clear from the foregoing, according to the present invention, the thickness of the steel plate can be controlled uniformly, and the occurrence of parts with poor thickness during biting can be prevented.

[Brief explanation of drawings]

Figure 1 is a load characteristic diagram showing the change in rolling pressure due to biting of the steel plate, Figure 2 is a diagram showing how a thick part is formed at the tip of the steel plate when biting, and Figure 3 is an impact load and oil A characteristic diagram showing the relationship between the amount of column compression, Fig. 4 is a block diagram showing an embodiment suitable for applying the present invention, and Fig. 5 shows an oil column height detector used in the embodiment of Fig. 4. 6th block diagram showing an example of
FIG. 7 is a flowchart showing the processing of the embodiment of the present invention.
Figures (a) and (b) are comparison diagrams of conventional products and products of the present invention. Agent Tatsuyuki Unuma (and 1 other person) Figure 6 Figure 7 (a) (b) -7

Claims (1)

[Claims] (1) Predict the impact load at the time of biting from the rolling load,
In a rolling mill that drives a hydraulic system to reduce the roll opening by the amount of oil column compression calculated based on this predicted value, the amount of oil column compression is corrected according to the actual oil column height, and the amount of oil column compression is corrected according to the actual oil column height. A roll opening setting method for a hydraulic vertical rolling mill, characterized in that the target roll opening is repeatedly calculated until the compression amount converges within a predetermined deviation, and the target roll opening at the time of completion of convergence is used for biting the steel plate. .