JPH05156372A - Method for operating continuous annealing line - Google Patents

Abstract

PURPOSE:To unify changing treatment of heat treatment condition in a continuous annealing line and to reduce poor heating part. CONSTITUTION:Based on an operating condition data table, combustion quantity difference between the combustion quantity of the present heating strip and the necessary combustion quantity of the next heating strip and velocity difference between the carrying velocity of the present strip and the carrying velocity of the next strip are obtd. Based on a forcing data table and a time constant data table, the forcing quantity of burner opening degree correcting quantity or the lik, and the operational condition shifting time are obtd. Based on the operational condition shifting distance multiplying the shifting time and the carrying velocity of the present strip, the operational condition changing position in the forcing quantity is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating, for example, a continuous annealing line, and more particularly to a method for changing operating conditions before and after a strip connecting portion.

[0002]

2. Description of the Related Art In a continuous annealing line in which a metal strip is continuously carried into a furnace and subjected to heat treatment, when the type of the strip to be treated is changed, the strip is heated to the rear end of the currently heated strip. The strip is welded and the operating conditions of the furnace are changed when the next strip is loaded into the furnace.

[0003]

[Problems to be Solved by the Invention] However, in the past,
The operator decides when to change the operating conditions based on his experience, and the operation is not uniform, and the defect processing part in the strip connection part is long, and in many cases, the defect is 200 m or more near the connection part. There was a problem that a part was generated.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in operating method of a continuous annealing line in which a metal strip is continuously carried into a furnace for heat treatment, operating conditions Based on the data table, the combustion amount difference between the combustion amount of the current strip that is currently heated and the required combustion amount of the next strip that is heated next, and the speed of the transport speed of the current strip and the required transport speed of the next strip The difference is obtained, based on a forcing data table that defines the relationship between the combustion amount difference and the forcing amount, the forcing amount corresponding to the combustion amount difference is obtained, and the speed difference and the operating condition change start time Based on the time constant data table that defines the relationship with the time required to transition to the required combustion amount of the next strip, determine the operating condition transition time corresponding to the above speed difference, and The operating condition transition distance is obtained by multiplying the switching condition transition time and the current strip transport speed, and the strip connection portion is upstream of the inlet of the furnace in the strip transport direction, and the operating condition transition is performed from the inlet of the furnace. The processing for shifting the operating condition of the forcing amount is started at the time of being transported to the vicinity of the position of the distance equal to the distance.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Figure 1 shows the continuous annealing line entrance side,
1 is a payoff reel, 2 is a cutting machine, 3 is a welding machine, 4 is a first bridle roll, 5 is an accumulator, and 8 is a second
Bridle rolls, 9 is a furnace. In the continuous annealing line, the metal strip 10 fed from the payoff reel 1 is wound between the upper and lower carriages 6 and 7 of the accumulator 5 via the first bridle roll 4, and then the second bridle roll 8 It is carried into the furnace 9 via the and heat-treated in the furnace 9 which is operated according to operating conditions which are predetermined based on the type of the strip 10, heat treatment conditions, finish conditions and the like.

When the strip 10 delivered from the pay-off reel 1 is replaced and another strip is heat-treated, first, the strip 10 a currently delivered from the pay-off reel 1 (hereinafter referred to as "current strip") 10a. Is cut by the cutting machine 2. Next, in place of the current strip 10a, a strip (hereinafter referred to as "next strip") 10b to be newly heat-treated is provided on the pay-off reel 1.
And the rear end of the current strip 10a and the front end of the next strip 10b are welded and integrated by the welding machine 3. From the cutting process to the welding process of the current strip 10a, the rear end of the current strip 10a is stopped at the welding position. During that time, the upper carriage 6 of the accumulator 5 descends and is wound around the accumulator 5. Present strip 1
The spare portion of 0a is sequentially fed out and continuously loaded into the furnace 9.

When the welding work is completed, the accumulator 5
The upper carriage 6 rises and the strip is wound between the upper and lower carriages 6 and 7 as shown in the drawing. Also,
The connection portion between the current strip 10a and the next strip 10b is located at a predetermined distance from the furnace inlet Pe (forcing start point P
s), the operating condition of the furnace 9 is the next strip 10
Switched for b. Then, while the strip connecting portion moves to the furnace inlet Pe, the temperature condition in the furnace changes from that for the current strip to that for the next strip. Therefore, when the strip connecting portion moves to the furnace inlet Pe, the temperature condition in the furnace is set for the next strip, and the next strip 10b is heated under this condition.

The process of changing the operating condition associated with the replacement of the strip will be described with reference to FIG. First, when the processing conditions such as the thickness information of the next strip 10b and the heating conditions are input to the operating condition change control device (not shown) during the heating process of the current strip 10a, the operating condition data table (not shown). Accordingly, the operating conditions for the next strip, such as the operating furnace temperature set value, the cooling zone various damper openings, and the cooling fan rotation speed set value for the next strip 10b, are determined. In the operating condition data table, in addition to the simulation result such as the set value of the furnace temperature calculated off-line, the required combustion amount for each operating condition calculated based on the simulation result is registered.

Next, the required combustion amount Q of the current strip 10a
A combustion amount difference ΔQMT between MT1 and the required combustion amount QMT2 of the next strip 10b is determined. QMT1 and QMT2
Is a value known by the thermal equilibrium calculation algorithm of the computer at the time of operation schedule, and this is used.
Further, from a forcing data table (not shown) showing the relationship shown in FIG. 3, a change correction amount such as a burner opening correction amount corresponding to the required combustion amount difference ΔQMT (hereinafter referred to as “forcing amount”). ) Determine ΔMV.

Further, a time (hereinafter, "time constant") T required to completely switch from the operating condition of the current strip 10a to the operating condition of the next strip 10b is determined. This time constant T has a constant relationship with the speed difference ΔLS between the transport speed LS1 of the current strip 10a and the transport speed LS2 of the next strip 10b, and is determined from the time constant data table showing the relationship shown in FIG. It In addition, the above-mentioned conveyance speed LS
1 and LS2 are determined from the above operating condition data table.

Subsequently, a connection portion tracking process is performed. This connection portion tracking processing is processing for detecting at which position the strip connection portion is currently transported,
Specifically, it is performed by providing small holes in the strip connection portion and detecting the small holes by photoelectric detectors arranged at predetermined intervals along the strip transport path.

Next, the forcing start timing, that is, the timing for switching the operating conditions of the furnace 9 is calculated. Specifically, as shown in FIG. 1, the position where the strip passes through the accumulator 5 is the forcing origin Po,
The distance from the forcing origin Po to the furnace inlet Pe is Xf, and the forcing starting point P is from the forcing origin Po.
Let Xp be the distance to s and Xs be the distance from the forcing start point Ps to the furnace inlet Pe.
(M) = LS1 (m / min) · T (min) Further, Xp is determined as Xp = Xf−Xs.

When it is detected that the strip connecting portion has passed the forcing origin Po by the tracking processing, the moving distance Xj of the connecting portion from the forcing origin Po is calculated based on the strip transport speed LS1. To be done. Then, the forcing process is started at or near the time when the movement distance Xj becomes Xp.

Specifically, Xp = 300 m and the current strip transport speed LS1 = 80 m / min are set, and
5 for determining the position of the forcing start point Ps.
A case where a counter that updates the count value every 00 ms is used will be described. In this case, while the counter updates the count value by "1", the strip connection section has 0.66
Move m (= 80 × 0.5 / 60). Therefore, the counter updates its count value by 450 while the strip connection portion moves from the forcing origin Po to the forcing start point Ps. That is, if forcing is started at the time when the count value is updated by 450 from the time when the strip connection portion passes through the forcing origin Po, if the tip of the next strip 10b reaches the inlet Pe of the furnace 9, the furnace 9 is reached. Is set to run the next strip 10b,
An appropriate heat treatment is applied to the next strip 10b.

[0015]

As is apparent from the above description, according to the method for operating a continuous annealing line of the present invention, an appropriate switching process is automatically performed according to the type of strip, so that the operator can be replaced. However, consistent processing is always possible. In addition, the defective product portion generated in the strip connection portion is significantly shortened, and the product yield is improved. Specifically, although the conventional strip connection portion has an average defective portion of 200 m, according to the present invention, the length of the defective portion is reduced to about half.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an introduction part of a continuous annealing line entrance side part.

FIG. 2 is an explanatory diagram showing a flow of strip connection processing.

FIG. 3 is a diagram showing a relationship between a strip speed difference and a time constant.

FIG. 4 is a diagram showing a relationship between a required combustion amount and a forcing amount.

[Explanation of symbols]

1 ... Pay-off reel, 2 ... Cutting machine, 3 ... Welding machine, 5 ... Accumulator, 9 ... Furnace, 10 ... Strip, Po ... Forcing origin, Ps ... Forcing start point, Pe ... Furnace inlet.

Claims (1)

[Claims] 1. A method for operating a continuous annealing line, in which a metal strip is continuously carried into a furnace for heat treatment, wherein a burning amount of a current strip that is currently heated and a next heating amount are based on an operating condition data table. The difference between the required combustion amount of the next strip and the required amount of combustion of the next strip, and the difference in velocity between the transport speed of the current strip and the required transport speed of the next strip are calculated to determine the relationship between the above combustion amount difference and the forcing amount. Based on the data table, the forcing amount corresponding to the above combustion amount difference is obtained, and the time constant data that defines the relationship between the speed difference and the time from the start of changing the operating conditions to the time required to move to the required combustion amount of the next strip Based on the table, find the operating condition transition time corresponding to the speed difference, and multiply the operating condition transition time by the current strip transport speed to transfer the operating condition transition time. Distance determined, the strip connection portion to a strip conveying direction upstream of the inlet of the furnace, at the point where the inlet of the furnace is transported to the vicinity of a distance equal to the operating conditions migration distance,
A method of operating a continuous annealing line, characterized in that the operation condition transition processing of the forcing amount is started.