KR20090025450A - Level setting method of rolling mill in the strip casting process - Google Patents

Abstract

A level setting method of a rolling mill in strip casting process is provided to ensure rolling stability by setting the rolling mill level in consideration of the temperature deflection of strip in the width direction. A level setting method of a rolling mill in strip casting process comprises a first step of calculating a rolling mill level by computing a pinch roll gap measured from a roll gap detector(3W,3D) of a pinch roll(2T,2B) using a calculated pinch roll level as input, obtaining a rolling mill level adjustment coefficient according to the temperature difference between the strip edges measured by a temperature sensor, and then producing the final rolling mill level; a second step of calculating a roll gap reference value at the work side and drive side of the rolling mill by using the final rolling mill level calculated in the first step; and a third step of controlling the roll gap of the rolling mill by using a servo valve(9W,9D) and a roll gap adjustment cylinder(7W,7D) so that the roll gap of the rolling mill follows the roll gap reference value calculated in the second step.

Description

LEVEL SETTING METHOD OF ROLLING MILL IN THE STRIP CASTING PROCESS}

The present invention relates to a method of setting a level of a rolling mill in a strip casting process, and more particularly, to a level of a pinch roll installed at the inlet side of a rolling mill for smooth rolling in response to a strip having various widthwise thicknesses and temperature profiles in a strip casting process. The present invention relates to a method for setting a level of a rolling mill in a strip casting process in which a level of a rolling mill can be set more smoothly and easily by using a temperature difference in a width direction of a strip.

In general, in the strip casting process, a strip is manufactured using a twin roll thin caster.

That is, the molten steel is supplied to the space formed by the two rotating casting rolls and the edge dams attached to both sides thereof to form a molten steel pool, and then the casting rolls and molten steel are contacted by rotating the casting rolls in opposite directions. This is to produce a strip by rapidly solidifying molten steel by heat leakage into the roll.

This strip casting is a new steel processing process that can produce 2 ~ 6mm thick hot rolled strips directly from molten steel to drastically reduce manufacturing cost, facility investment cost, energy consumption and pollution emission.

At this time, in order to secure the surface quality, structure refinement, and dimensional quality of the strip, the strip made through the sheet casting machine is rolled at a rolling rate of 30 to 40% by a rolling mill installed at the back of the sheet casting machine. In order to carry out the management of the widthwise thickness and temperature profile of the cast strip is very important.

For example, if left and right symmetry is not secured based on the width center portion of the strip, if the level of the rolling mill is not set accurately, rolling may cause stripping or shape defects, thereby greatly reducing productivity and error rate.

In addition, the strip thickness and temperature profile of the twin roll type sheet casting machine are generated by the difference in the solidification shell formation state of the center of the cast steel along the width direction of the casting roll, and the shape of the casting roll, the molten steel flow in the molten metal, and the mixing of the skull It is formed differently according to various operating conditions, and these conditions may change with time.

Therefore, the thickness and temperature profile of the cast strip can take a variety of forms, taking advantage of the wedges of the strip when setting the level of the rolling mill, i.e. the deviation between the thickness of the edges at the work side and the drive side of the strip. It is a common way to set up.

Prior arts relating to the level setting method of a rolling mill using such measured or predicted strip wedges include Japanese Patent Laid-Open No. 2002-126813, Japanese Patent Laid-Open 2001-269708, Japanese Patent Laid-Open 2000-94023, and the like.

However, the disclosed prior art has a limitation in that it is difficult to set the level of the rolling mill for stable rolling when the thickness profile is not the first or second curve, and the temperature deviation between the edges of the work side or the drive side of the strip There was also a limit that the degree of level setting of the rolling mill was not reliable when large.

The present invention was created in view of the above-described problems in the prior art, and uses a pinch roll level to reduce an error that may occur when calculating a wedge from a strip thickness profile, and uses a strip width direction temperature deviation. It is a main object to provide a method for setting the level of the rolling mill in the strip casting process to ensure the rolling stability by setting the rolling mill level in consideration of.

The present invention provides a means for achieving the above object, in the method for setting the level of the rolling mill in the strip casting process; The pinch roll gap (RGw, RGd) measured from the roll gap detector of the pinch roll is substituted into the following [Equation 1] as the input pinch roll level (Lvl_p) to calculate the rolling mill level through [Equation 2], and the temperature detector A first step of calculating a final mill level Lvl_f through [Equation 4] after obtaining a mill level adjustment coefficient a according to a temperature deviation dT between strip edges measured by Equation 4; A second calculation of the roll gap reference values RGrw and RGrd at the work side and the drive side of the rolling mill for level control using the final mill level Lvl_f calculated in the first step through [Equation 5, 6] Steps; Rolling mill in the strip casting process, characterized in that the rolling gap of the rolling mill using a servo valve and the roll gap adjustment cylinder to control the roll gap of the rolling mill to follow the roll gap reference value (RGrw, RGrd) calculated in the second step Provides a level setting method.

[Formula 1] Lvl_p = RGw-RGd

[Formula 2] Lvl_r1 = Kg1 × Lvl_p

[Equation 3] a = f (dT)

[Equation 4] Lvl_f = a × Lvl_r1

RGrw = RGr + Lvl_f / 2

RGrd = RGr-Lvl_f / 2

At this time, the rolling mill level adjustment coefficient (a) is a proportional constant, which is characterized by being calculated as a function of temperature alone.

According to the present invention, when the level of the rolling mill is set in the strip casting process, the level of the rolling mill is appropriately set in response to various types of casting strip thickness profiles and temperature deviations between the strip edges. Problems can be ameliorated, resulting in significant contributions to improved productivity and error rate.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

1 is an exemplary configuration showing a level setting process of the rolling mill in the strip casting process according to the present invention.

As shown in FIG. 1, the present invention is to set the level of the rolling mill at the time of strip casting by using the level of the pinch rolls 2T and 2B and the widthwise temperature deviation of the strip 1.

To this end, the control signal of the rolling mill level controller 11 and the rolling mill level controller 11 which receives the value calculated by the rolling mill level set calculator 10 and the rolling mill level set calculator 10 to control the level of the rolling mill. In accordance with the rolling mill roll gap controller 12 for adjusting the roll gap of the rolling mill.

At this time, the rolling mill level setting calculator 10 calculates the roll gap detectors 3W and 3D for detecting the roll gaps of the pinch rolls 2T and 2B, which give tension to the strip 1, and the surface temperature of the strip 1; The detection value is received from the detecting temperature detector 4, and the level value for setting the level of the rolling mill is calculated.

That is, the rolling mill level setting calculator 10 uses the pinch roll gaps RGw and RGd measured from the roll gap detectors 3W and 3D as inputs to the pinch roll level Lvl_p calculated by Equation 1 below. The rolling mill level is calculated by the following [Equation 2], the rolling mill level adjustment coefficient (a) according to the temperature deviation (dT) between strip edges measured by the temperature detector 4 is obtained, and the final rolling mill level is obtained by [Equation 4]. (Lvl_f) is calculated.

[Formula 1] Lvl_p = RGw-RGd

[Formula 2] Lvl_r1 = Kg1 × Lvl_p

[Equation 3] a = f (dT)

[Equation 4] Lvl_f = a × Lvl_r1

Here, Kg1 is a gain, f (dT) is a function of the temperature deviation dT, and a constant value coefficient a can be obtained through an application test, that is, many experiments under various conditions.

On the other hand, the rolling mill level controller 11 uses the final mill level Lvl_f calculated by Equation 4 in the rolling mill level set value calculator 10 for the mill work side and drive for level control. The roll gap reference values RGrw and RGrd at the drive side are calculated by the following equations (5, 6).

RGrw = RGr + Lvl_f / 2

RGrd = RGr-Lvl_f / 2

Here, RGr is a rolling mill roll gap set value calculated in consideration of the thickness of the entry and exit side.

The rolling mill roll gap controller 12 uses the servo valves 9W and 9D and the roll gap adjusting cylinders 7W and 7D to determine the roll gap reference values RGrw and RGrd calculated by the rolling mill level controller 11. Control to follow.

At this time, the roll gap of the rolling mill is fed back by the value detected by the roll gap detectors 8W and 8D and is made by the adjustment operation of the roll gap adjustment cylinders 7W and 7D.

In addition, reference numerals 5T and 5B denote 'work rolls', and 6T and 6B denote 'backup rolls'.

As described above, the present invention reduces the error that can occur when calculating the wedge from the strip thickness profile, and the problem that the level setting of the rolling mill is lowered when the edge temperature deviation at the work side and the drive side of the strip is large. In order to solve, the rolling mill level is set by using the pinch roll level and the width direction temperature deviation of the strip to ensure the stability of rolling.

1 is an exemplary configuration showing a level setting process of the rolling mill in the strip casting process according to the present invention.

♧ description of the symbols for the main parts of the drawing ♧

1 .... strip

4 .... temperature detector

10 .... Roller Level Set Point Calculator

11 .... roller level controller

12 ... rolling mill roll gap controller

Claims (2)

A method for setting a level of a rolling mill in a strip casting process; The pinch roll gap (RGw, RGd) measured from the roll gap detector of the pinch roll is substituted into the following [Equation 1] as the input pinch roll level (Lvl_p) to calculate the rolling mill level through [Equation 2], and the temperature detector A first step of calculating a final mill level Lvl_f through [Equation 4] after obtaining a mill level adjustment coefficient a according to a temperature deviation dT between strip edges measured by Equation 4; A second step of calculating the roll gap reference values (RGrw, RGrd) at the work side and the drive side of the rolling mill for level control using the final mill level Lvl_f calculated in the first step through [Equation 5, 6] Wow; Rolling mill in the strip casting process, characterized in that the rolling gap of the rolling mill using a servo valve and the roll gap adjustment cylinder to control the roll gap of the rolling mill to follow the roll gap reference value (RGrw, RGrd) calculated in the second step How to set the level. [Formula 1] Lvl_p = RGw-RGd [Formula 2] Lvl_r1 = Kg1 × Lvl_p [Equation 3] a = f (dT) [Equation 4] Lvl_f = a × Lvl_r1 RGrw = RGr + Lvl_f / 2 RGrd = RGr-Lvl_f / 2 The method according to claim 1; In the first step, the rolling mill level adjustment coefficient (a) is a proportional constant, which is calculated as a function of temperature only.

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