JPH072246B2 - Control method of scale removing device for hot rolled coil - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a scale removing device for a hot rolled coil, which efficiently removes scale produced on the surface of the hot rolled coil.

2. Description of the Related Art Since a hot-rolled coil, which is a base material to be cold-rolled, is hot-rolled at a predetermined high finishing temperature, three types of oxidation of FeO, Fe ₃ O ₄ and Fe ₂ O ₃ are formed on its surface. Things (hereinafter “scale”)
Say. ) Is formed in a laminated manner. This scale is removed by mechanical and chemical means before it is cold rolled.

In order to improve the efficiency of the scale removing operation and the subsequent operations, the hot-rolled coil is welded and the scale removing operation is performed. By welding the hot-rolled coil in this manner, the scale removing work or the like can be continuously performed, and the working time can be shortened.

Problems to be Solved by the Invention However, the scale removal work is different even if the material conditions of the welded hot rolled coil are different, especially the conditions of the chemical pickling part, the acid solution temperature or a large change in the acid concentration is difficult,
Materials that have poor descaling properties reduce time-consuming productivity. For this reason, a mechanical scale removing device is installed in front of the chemical pickling section, but the conditions and effects are unclear, so the scale removing capacity becomes excessive, and conversely, it becomes insufficient, resulting in In many cases, productivity improvement cannot be achieved.

As described above, in the scale removing work in which both the mechanical scale removing and the scale removing by pickling are used together, it is necessary to change the condition of mechanical scale removing depending on the material condition.

An object of the present invention is to provide a method for controlling a scale removing device for a hot-rolled coil, which is capable of operating scale removal by pickling most efficiently by controlling working conditions for mechanical scale removal. .

Means for Solving the Problems The present invention relates to a method for controlling a scale removing device for a hot rolled coil, wherein the scale of the hot rolling coil is removed by a scale removing device, and then pickling is performed. Scale thickness removed by
Controlling a scale removing device for a hot rolling coil, characterized in that at least one of ε, W, N and V is changed and adjusted so that t is obtained by the following equation and Δt falls within a predetermined range. Is the way.

Δt = (aε + b) · N · W / V where ε is the elongation rate of the hot-rolled coil, which is changed by the elongation rate changing means for angularly displacing the hot-rolled coil around the axis parallel to the width direction, a and b is a constant having a positive value determined by the hot-rolling coil removing device and the material conditions of the hot-rolling coil, N is the number of stages used in a brush device of a plurality of stages provided for grinding the scale of the hot-rolling coil, W is the power of the drive source per stage of the brush device, and V is the traveling speed of the hot rolling coil.

Action In the present invention, the scale of the hot-rolled coil is mechanically removed by the scale removing device and then chemically removed by pickling. This scale removing device is composed of an elongation changing means and brush devices arranged in a plurality of stages in the longitudinal direction of the hot rolling coil. When the scale thickness removed by the scale removing device is Δt, Δt is experimentally expressed by the following equation.

Δt = (aε + b) · N · W / V As the elongation of the hot-rolled coil increases, Δt increases as it increases, and even if this becomes zero, Δt does not become zero, so Δt becomes (aε + b). Proportional. a and b are positive constants related to the scale removing device and material conditions.

Further, Δt increases in proportion to the number of stages N of the brush device used, and also increases in proportion to the power W of the drive source for driving the brush device per stage.

As the traveling speed V in the scale removing device of the hot-rolled coil is higher, Δt is inversely proportional to the smaller value. From these, the above equation is derived.

The scale removing device uses at least one of ε, W, N, and V so that Δt obtained according to the above equation is within a predetermined range.
It is controlled by changing one.

Embodiment FIG. 1 is a block diagram showing the structure of a scale removing device 1 in which a control method according to an embodiment of the present invention is implemented. The hot-rolled coil 2 formed by the hot-rolling process is adjusted by the bridle roll 3a to adjust the tension applied to the hot-rolled coil 2 and then stretches to form a crack in the scale generated on the surface of the hot-rolled coil 2. It passes through a scale breaker 4, which is a rate changing means. Hot rolled coil 2 with scale breaker 4
The elongation rate ε of is defined by the first equation.

Here, l ₀ means the unit length of the hot-rolled coil before input to the scale breaker 4, and 1 means the length of the unit length output from the scale breaker 4. Scale breaker 4
Two rolls 41, 42 are provided on the front and back sides at short intervals in the traveling direction of the hot-rolled coil 2 which is tensioned by the bridle rolls 3a, 3b, 3c, and the hot-rolled coil 2 is rolled by the rolls 41, 42. It is a device that applies pressure from both the front and back sides in the direction perpendicular to the traveling direction to give elongation to the material and form a tear in the scale,
The elongation drive unit 5 adjusts the force applied to the rolls 41, 42.

The larger the elongation given to the hot-rolled coil 2, the larger the cracks are formed in the scale, and the scale is easily ground by the grinding device 6 described later. The scale thickness Δt removed by the scale removing device is proportional to the stage number N of the brush device used in the grinding device 6 and the driving power W per stage of the brush device, and is inversely proportional to the traveling speed V of the hot rolling coil. Then, it is expressed as in the second equation.

Δt = C ・ N ・ W / V (2) where C is called the scale grindability coefficient,
A large elongation is given to the hot rolled coil 2 and a large scale crack is formed on the scale. According to an experiment conducted by the inventor, the coefficient of ease of grinding C and the elongation rate ε have a relationship of a third equation C = aε + b (3) represented by a linear equation, and the real numbers a and b are used. It depends on the scale remover and material conditions. In the equipment used by the inventor, when the material condition is MCT material or HCT material, the third formula is Δt of the second formula is μm, W is the number of lots per 1 mm width of the hot rolled coil W / mm, and V is m. It was found that when expressed in / min, the following fourth formula was obtained.

C = 0.28ε + 5.54 (4) The relationship between C and ε may be a quadratic or more, but the coefficient of ε squared or more is small, and the practical ε range (0
In the case of ˜6 (%)), the fourth formula is sufficient. The elongation rate ε is usually used in the range of 1 to 3%.

The scale of the hot-rolled coil 2 that has been torn by the scale breaker 4 is mechanically removed by the grinding device 6. The grinding device 6 is composed of brush devices 61, 62, ..., 6n arranged in a plurality of stages in the longitudinal direction of the hot-rolled coil. The one-stage brush device, for example, 61, is composed of a pair of brushes 611 and 612 provided on both front and back surfaces of the hot rolling coil 2. To be ground. Each brush device 61,6
2, ..., 6n are controlled by the brush driving device 7 in terms of the number of stages N used and the driving power W. For example, brush device 61
Is used, the pair of brushes 611 and 612 are driven by the brush driving sources 611a and 612a, and the brush driving sources 611a and 612a are driven.
The power W of 2a is controlled by the brush controller 7. When the scale on the hot-rolled coil 2 is thick, the number N of stages of use of the brush device 61 or the like increases or the driving power W per stage increases.

When the scale on the hot-rolled coil 2 is removed by the grinding device 6, the hot-rolled coil 2 moves to the next step, the pickling step, via the bridle roll 3d.

In the pickling step, the hot rolled coil 2 is passed through a pickling tank of hydrochloric acid or sulfuric acid to remove the scale. It is passed through the pickling tank for a predetermined time (for example, 5 to 10 seconds). This pickling time is determined by the equipment capacity before and after, especially the pickling time extension according to the scale thickness, i.e. lowering the hot rolling coil passing speed must be avoided because it will reduce the productivity, The scale is removed by a scale removing device until the scale is completely removed in the pickling equipment.

FIG. 2 is a configuration diagram for explaining the relationship between the scale removing device 1 and the pickling equipment 11. The hot-rolled coil 2 produced by hot rolling is welded to the hot-rolled coil 2 before being sent to the scale removing device 1 in order to continuously perform scale removal and subsequent steps. The hot rolled coil 2 is sent to the scale removing device 1 via the inlet loop 10a. In the scale removing device 1 and the pickling equipment 11, the hot rolling coil 2
Therefore, it is necessary to provide a storage device for the hot-rolled coils on the inlet side and the outlet side in an amount commensurate with the time required for work and labor. In this embodiment, an inlet loop 10a and an outlet loop 10b are used as this storage device. These loops can move in the direction of arrows 12a-12d, and
By changing the storage amount of the hot-rolled coil, the hot-rolled coil 2 can be continuously passed through the scale removing device 1 and the pickling equipment 11 even during the welding operation of the hot-rolled coil. Also,
The direction of the hot rolled coil 2 is changed by the deflector rolls 13a to 13d, and the hot rolled coil 2 is sent to a predetermined facility.

Next, an embodiment of the control method according to the present invention will be described below. FIG. 3 is a control flow chart for realizing the control method according to the embodiment of the present invention. The processing of each step will be described below. First, in step s1, the stage number N of the brush devices 61, 62, ..., 6n used in the grinding device 6 is initialized. This initial set value is determined by the temperature of hot rolling coil 2 during hot rolling. The thickness of the scale ground by the grinding device 6 is generally determined by the number of steps, and as the number of steps increases, more scale is removed. When the number of stages is set in step s1, the process proceeds to step s2, and the coefficient C of ease of grinding of the scale is calculated from the elongation rate ε of the hot rolled coil 2 by the scale breaker 4.

In step s3, the electric power W supplied to the brush device 61 or the like used is calculated. A certain constant value is initially selected for the electric power W and is adjusted after the calculation of Δt described later. When the electric power supplied to the brush device used, for example 61, increases, the pressing force of the brushes 611 and 612 against the hot-rolled coil 2 increases, and the scale is ground more.

At step s4, the traveling speed V of the hot rolling coil 2 is set. The traveling speed V is set to the slower value of the line speeds of the equipment capacity of the entrance side and the exit side of the scale removing device 1.

The parameter that determines the scale thickness to be ground is the step
When set in s1 to step s4, in step s5,
The scale grinding thickness Δt is calculated according to the fifth equation.

Δt = (aε + b) · N · W / N (5) When the scale grinding thickness Δt is calculated in step s5, it is determined in step s6 whether the grinding thickness Δt is within the range of the scale thickness to be ground. Is judged. If the scale grinding thickness Δt is outside the scale thickness range, for example, the scale grinding thickness Δt is larger than the scale thickness generated in the hot rolled coil 2, or the scale grinding thickness Δt is smaller than the scale thickness generated in the hot rolled coil 2, If the scale thickness cannot be removed by the washing facility 11, the process proceeds from step s6 to step s1 to set the above parameters again.

If the scale grinding thickness Δt is within the scale thickness range at step s6, the scale removal is performed by the parameters set at steps s1 to s4.

FIG. 4 is a graph showing the relationship between the temperature during hot rolling and the scale thickness generated in the hot rolled coil 2. In FIG. 4, the horizontal axis represents the temperature when the hot-rolled coil 2 is hot rolled, and the vertical axis represents the scale thickness generated in the hot-rolled coil 2. Line 1 in FIG. 4 is a line showing the relationship between temperature and scale thickness during hot rolling, and the thickness of the scale formed on the surface of hot rolled coil 2 is almost uniform depending on the temperature during hot rolling. The thickness increases as the temperature rises.

A line 12 shown by a broken line in FIG. 4 is a line showing the thickness of the scale ground by the grinding device 6, and is the hot rolled coil 2
However, the scale thickness to be ground differs depending on the number N of stages such as the brush device 61 used by the grinding device 6. That is, the number N of stages of the brush device 61 or the like used by the grinding device 6 is generally determined by the winding temperature when the hot-rolled coil 2 is hot-rolled. For example, when the temperature is in the range of t1 to t2, the grinding is performed. Device 6
The number of stages N such as the brush device 61 used by is 1 and the temperature t2
When the temperature is within the range of t3, the number of stages N is set to 2.
In this way, the amount of scale to be ground in the grinding device 6 is determined by the number of stages N, and the scale remaining after grinding by the grinding device 6 is removed by the pickling equipment in the subsequent step of the scale removing device 1. Furthermore, the temperature during hot rolling is, for example,
In the case of t1 to t2, the use stage number N of the brush device 61 and the like is 1, but the driving power W of the brushes 611 and 612 is small when it is close to t1 and is large when it is close to t2.

FIG. 5 is a graph for explaining the elongation rate ε of the scale breaker 4 determined by the temperature during hot rolling. Since the scale becomes thicker as the winding temperature during hot rolling rises, it is necessary to increase the elongation ratio ε of the hot rolled coil 2 depending on the winding temperature during hot rolling. Therefore, when the winding temperature of the hot-rolled coil 2 during hot rolling is determined, the scale breaker 4 obtains the elongation shown by the line l3 in FIG.
Is controlled by the slab to give a crack to the scale of the hot rolled coil 2. As described above, by changing the elongation ratio ε given to the hot rolled coil 2 depending on the winding temperature during hot rolling, grinding in the grinding device 6 can be easily performed.

As described above, according to the present embodiment, by controlling the operating conditions of the scale removing device, the scale removing device and the pickling equipment can always operate efficiently and efficiently.

As described above, according to the present invention, the thickness Δt of the scale to be ground is obtained from the elongation rate ε, the power W of the brush drive source, the number N of stages of the brush, and the traveling speed V of the hot rolling coil.
Since t is controlled to fall within a predetermined range, scale removal can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a scale removing device 1 in which a control method according to an embodiment of the present invention is implemented, and FIG. 2 is a configuration diagram for explaining the relationship between the scale removing device 1 and pickling equipment 11. FIG. 3 is a control flow chart for realizing the control method according to one embodiment of the present invention, and FIG. 4 is a graph showing the relationship between the temperature during hot rolling and the scale thickness generated on the hot rolled coil. FIG. 5 is a graph for explaining the elongation rate ε of the scale breaker 4 determined by the temperature during hot rolling. 1 ... scale removing device, 2 ... hot rolling coil, 3a-3d ...
… Bridle rolls, 4 …… Scale breakers, 5 ……
Elongation rate drive device, 6 ... Grinding device, 7 ... Brush drive device

Claims (1)

[Claims] 1. A method for controlling a scale removing device for a hot rolling coil, comprising removing scale of a hot rolling coil by a scale removing device and then performing pickling, wherein the scale removing device removes the scale. Scale thickness Δ
Controlling a scale removing device for a hot rolling coil, characterized in that at least one of ε, W, N and V is changed and adjusted so that t is obtained by the following equation and Δt falls within a predetermined range. Method. Δt = (aε + b) · N · W / V where ε is the elongation rate of the hot-rolled coil, which is changed by the elongation rate changing means for angularly displacing the hot-rolled coil around the axis parallel to the width direction, a and b is a constant that is a positive value determined by the scale removing device and the material condition of the hot rolling coil, N is the number of stages used in the brush device of multiple stages provided for grinding the scale of the hot rolling coil, and W is The magnitude of the power of the drive source per stage of the brush device, V is the traveling speed of the hot rolling coil.