JPH0976050A - Method and device for controlling molding powder thickness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of slab quality and restraint breakout by calculating a powder thickness of each region in a mold from the powder thickness relative distribution and the powder thickness representative value and controlling a powder charging quantity based on the difference to an objective value. SOLUTION: A powder thickness representative value T (*) is calculated by inputting detecting signals of a molten steel level gage 12 and a powder level gage 13 into a controller 16. The image signal from two cameras 14 arranged as sandwiching an immersion nozzle 5 is inputted into an image processor 17, for example, by obtaining the powder thickness relative values ΔTA-ΔTD in four regions A-D, the values are inputted into the controller 16. By comparing the average powder thickness TA-TD calculated by the controller 16 to the powder thickness control objective value TO, the result is outputted to a drive device 20, a powder charging quantity from a powder supplying machine 7 is controlled. Thus, the slab quality is improved and the restraint breakout due to shortage of the powder molten layer is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold powder thickness control method and a method for controlling the layer thickness of mold powder to be cast on a molten steel surface in a mold in continuous casting to be uniform and uniform throughout the mold. The present invention relates to a mold powder feeding device used for.

[0002]

2. Description of the Related Art In a continuous casting method, a dipping nozzle for injecting a molten metal under a molten metal surface in a mold and a powdery or granular mold powder (CaO, SiO ₂ as a main component) for covering the molten metal surface in the mold are used. The synthetic slag) is adopted. This mold powder melts the part in contact with the molten metal in the mold and forms a powder layer, a sintered layer, and a molten layer in order from the top to suppress the oxidation of the molten metal, prevent inclusion of inclusions, trap inclusions, mold The powder melt layer flows between the solidification shell and the solidification shell to prevent lubrication and quenching.

When the amount of such mold powder is insufficient, a restrictive breakout occurs due to friction between the mold and the solidified shell, the surface quality of the slab deteriorates, and the quality of the slab even if excessively charged. It is not preferable.
Therefore, in order to prevent operational problems such as breakouts and deterioration of the surface quality of the slab, add and replenish the amount equivalent to the amount consumed during casting to make the mold powder a uniform layer thickness without excess or deficiency. It is important to keep.

[0004] Conventionally, the mold powder is supplied and replenished by visually observing the powder red heat state to judge the powder thickness, or by inserting a wire or the like to measure the powder thickness according to the melting loss or the powder adhesion state. However, there are problems such as detection after the powder is insufficient or the powder thickness cannot be measured continuously and accurately. Also, there is a safety problem because it is manually performed. As means for solving such a problem, the following means for automatically adding mold powder has been proposed.

Japanese Patent Publication No. 5-71339 (Powder input amount control device in continuous casting machine) As shown in FIG. 5 (a), the molten steel level is measured by the molten steel level meter 50 and the powder level meter 51 is used. The powder upper surface level is measured, and in the main control command device 52, the powder thickness is obtained from the difference between the molten steel molten metal surface level and the powder upper surface level, and the correction amount is calculated by comparing this powder thickness with a preset target value. The calculated value is output to the drive unit 54 of the powder cutting machine 55 to instruct a new powder conveyance amount. At the same time, the actual powder transport amount is measured by a measuring device 56 such as a load cell attached to the powder transport pipe 55a, and the correction control amount of the powder input amount is corrected by the sub-control command device 53. An alarm is output by comparing the amount of change with a reference value. Thereby, the powder thickness can be automatically adjusted, and at the same time, an abnormality of the powder cutting device can be detected.

Japanese Laid-Open Patent Publication No. 2-30358 (powder charging device for continuous casting) As shown in FIG. 5B, an infrared camera 60 and a manipulator 61 for powder charging are arranged above the mold to form an image. The processing device 62 processes the image signal from the camera to obtain the position and size of the powder-deficient portion, and the control device 63 calculates the pouring position and pouring amount of the powder to control the operation of the manipulator 61 and the powder supplying amount. ing. As a result, the powder can be immediately added to the powder-deficient portion and the optimum amount of powder can be added.

[0007]

However, according to the method of the prior art described above, the measurement of the powder level meter, that is, the measurement of the powder thickness is performed only at one representative point in the mold, and a local abnormality in the mold is generated. If the flow of molten metal in the mold is abnormal due to uneven flow, or if other operating conditions (such as type of bower used or immersion nozzle) are different, the powder thickness in the mold Since the distribution is non-uniform, it is hard to say that it is practical.

Further, according to the method of the prior art, although it is possible to detect an abnormal amount of the powder cutting device, it is impossible to detect a local powder consumption state in the mold. The powder consumption varies depending on the casting conditions, and the casting conditions also continuously change from moment to moment, so the powder consumption must be continuously controlled during casting. Also, the powder consumption changes due to changes in the powder physical properties that cause deterioration of the slab surface quality, breakout, etc.It is important to know the change in the powder consumption along with constant control of the powder thickness. is there.

Next, with the method of the prior art, the lack of powder thickness can be detected. However, since the lack of powder is grasped on the basis of the temperature difference on the powder surface, the powder thickness in each region in the mold can be detected. Quantitative grasp is not possible and it is insufficient for quality control. Further, since the powder is supplied after it is insufficient, it must be feared that the quality of the surface of the slab is adversely affected. Furthermore, in this case as well, it is impossible to know the change in powder consumption.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to quantitatively grasp the powder thickness distribution of each region in the mold, and to obtain the layer thickness of the mold powder. Can be automatically controlled to an arbitrary constant thickness and even in each region in the mold. Furthermore, it is possible to continuously obtain the change in powder consumption in each region in the mold and continuously. It is to provide a method and apparatus for controlling mold powder thickness that can be monitored.

[0011]

The method for controlling the mold powder thickness according to the present invention is, as shown in FIGS. 1 and 2, a mold powder to be poured from the powder feeder 7 onto the molten steel surface in the mold 1. When controlling the layer thickness of 6, the molten steel level in the mold and the powder top level are measured to obtain the powder thickness representative value T (*) in the mold, and the image signal from the camera installed above the mold is calculated. After processing, the powder thickness relative distribution (powder thickness relative value ΔT _n ) of each area in the mold (the surface of the powder inside the mold is divided into n pieces) is obtained, and this powder thickness relative distribution and the powder thickness representative value T (* ), The powder thickness T _n of each region in the mold is calculated, and based on the difference between the powder thickness T _{n of} each region and the preset powder thickness control target value T ₀ , the powder feeder for each region is calculated. It is characterized in that the amount of powder input from 7 is controlled.

Furthermore, in this method for controlling the mold powder thickness, in addition to the automatic control of the powder thickness, the time t ₁ during which the powder supply drive source of the powder supply machine is ON in each region in the mold, The powder amount Q ₁ is calculated from the powder amount q per unit time of the powder feeder, and the powder consumption amount per unit molten steel amount is calculated from the powder amount Q ₁ and the molten steel casting amount R ₁ per unit time. S is obtained for each area in the mold, and the abnormality of the mold powder is monitored by the powder consumption amount S _n of each area.

As shown in FIGS. 1 and 2, the mold powder feeding device for carrying out such a method comprises a powder feeder 7 for feeding the mold powder 6 onto the surface of the molten steel in the mold 1 and the inside of the mold. Level gauges 12 and 13 for measuring the molten steel level and powder top level, a camera 14 for imaging the powder surface in the mold, an image processing device 17 for processing the image signal from this camera, and a level detection signal. Inside the mold from the powder thickness representative value T (*) and the powder thickness relative distribution (powder thickness relative value ΔT _n ) of each area (dividing the powder surface in the mold into n pieces) in the mold obtained from the image processing signal. calculating a powder thickness T _n of each region, from the powder feeder 7 based on the difference between the powder thickness control target value T ₀ previously set the powder thickness T _n for the respective regions It consists processing control unit such as control unit 16 which controls the powder input.

The second mold powder feeding device is, as shown in FIGS. 1 and 2, a powder feeder 7 for feeding the mold powder 6 onto the molten steel surface in the mold 1.
A level meter 12, 13 for measuring the molten steel surface level and the powder upper surface level in the mold, a camera 14 for imaging the powder surface in the mold, and an image processing device 17 for processing an image signal from the camera. Representative value of powder thickness T (*) obtained from the level detection signal and each region in the mold obtained from the image processing signal (n
(Divided into individual pieces) and the powder thickness relative distribution (powder thickness relative value ΔT _n ) and the powder thickness T _n of each region in the mold.
Is calculated, and the powder input amount from the powder feeder 7 is controlled based on the difference between the powder thickness T _{n in} each area and the preset powder thickness control target value T _0, and further in each area in the mold. powder feed drive source powder feeder 7 is a time t ₁ which is the ON, to calculate the powder charged amount Q ₁ from the powder charging amount q per unit of powder feeder time, this powder input amount Q ₁ A powder consumption amount S per molten steel unit casting amount is obtained for each region in the mold from the molten steel casting amount R ₁ per unit time, and an alarm is output when the powder consumption amount S _{n in} each region exceeds a set range. It is composed of arithmetic processing control means such as the control device 16.

The powder input amount is controlled by ON / OFF controlling the powder supply drive source of the powder supply device 7 which moves at a predetermined speed while keeping the powder input amount q constant, or by supplying the powder supply amount q constant. The movement of the machine 7 is temporarily stopped. Further, the powder feeding amount q of the powder feeder 7 which moves at a predetermined speed may be controlled.

When the powder supply drive source of the powder supply machine 7 is ON / OFF controlled, the controller 16 calculates the calculated powder thickness T _n from the preset powder thickness control target value T ₀ . If it is smaller, an ON signal is output to the powder supply motors 10 and 11 of the powder supply device 7, and if it is larger than the powder thickness control target value T ₀ , an OFF signal is output to the motors 10 and 11. The screw etc. of the powder supply device 7 starts to operate by the ON signal, and the preset powder supply amount q per unit time
Then, the mold powder 6 is charged, and the operation of the screw or the like is stopped by the OFF signal.

At this time, the time t ₁ during which the supply command to the powder supply device 7 is the ON command is stored in the microcomputer in the controller 16 for each area in the mold, and the time t ₁ By multiplying the powder supply amount q of, the powder supply amount Q ₁ (= t ₁ × q)
Is calculated for each area. On the other hand, casting conditions (slab drawing speed V _c1 , slab casting width W _1, etc.) are input from the process computer 18, and the molten steel casting amount R ₁ per unit time is calculated. Next, from the powder supply amount Q _{1 for} each region in the mold and the molten steel casting amount R ₁ per unit time, the powder consumption amount S (= ΣQ ₁ / R ₁ ) at every arbitrary time t (for example, every 5 minutes). Xt) is calculated, and the powder consumption amount S _n of each area is the upper limit value S _H and the lower limit value S _{H.
When it} goes out of the setting range of _L , a warning is given with a buzzer, etc. and an alarm is output on the CRT screen.

Even when the movement of the powder feeder 7 is temporarily stopped with the powder input amount q being constant, the temporary stop time is adjusted based on the difference between the powder thickness T _n and the target value T _0. The powder thickness can be automatically controlled, and the powder consumption amount can be monitored by using the time t ₁ when the supply command is the ON command during movement and stop. Also, when controlling the powder input amount q of the powder feeder 7 moving at a predetermined speed, the powder thickness T _n
And a powder charging amount automatic control of powder thickness by adjusting the q, also time powder charging amount of the variable q 'and its supply command is ON command t ₁ based on the difference between the target value T ₀ Can be used to monitor powder consumption.

[0019]

In the above-mentioned structure, the powder thickness at one point in the mold, that is, the powder thickness representative value T (*), is determined from the difference between the molten steel level in the mold and the powder upper level.
There is always measured at the same time a camera and the image processing by the powder thickness relative distribution, i.e. powder thickness relative value [Delta] T _n in each region in the mold is measured, the powder thickness relative value [Delta] T _n the powder thickness representative value T By performing proportional calculation using (*), the powder thickness T _n of each region in the mold can be obtained, and the powder thickness distribution in the mold can be quantitatively grasped. In each region in the mold, the powder feeding amount by the powder feeder 7 is controlled so that each powder thickness T _n matches the powder thickness control target value T ₀ . As a result, during casting, the powder thickness is automatically controlled to an arbitrary fixed level and evenly throughout the mold, greatly suppressing variations in slab surface quality due to changes in the conventional powder thickness, and reducing local variations. Insufficient powder, that is, restraint breakout due to insufficient lubrication of the powder melt layer is prevented.

Simultaneously with such constant control of the powder thickness, the controller 16 stores the command time t ₁ for supplying the powder to the powder feeder 7, and the process computer 1
Various values such as the slab drawing speed V _c1 and the slab casting width W ₁ which change from moment to moment are input from 8, and the powder supply amount Q ₁
And the molten steel casting amount R ₁ per unit time, the powder consumption amount S of the powder per molten steel unit casting amount is calculated for each region in the mold, and the powder consumption amount S _n in each of these regions is the upper limit value _SH , When it goes out of the setting range of the lower limit value S _L , an alarm is issued. As a result, it is possible to detect local abnormalities in the mold due to uneven flow due to blockage of the dipping nozzle, abnormalities in powder physical properties, etc., and operational troubles (for example, restraint caused by extremely low powder consumption). It is possible to prevent both sex breakout and quality trouble.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in the drawings. As shown in FIG. 1, molten steel 2 in a ladle (not shown) is poured into a mold 1 through a tundish 3, a sliding nozzle device 4 and a dipping nozzle 5, and the molten steel side surface is subjected to primary cooling in the mold 1. A solidified shell 2'is formed on the surface. Mold powder 6 is supplied onto the molten steel surface in the mold 1 through a powder supply pipe 8 of a powder supply machine 7.

The powder feeder 7 cuts the molding powder 6 in the feeding hopper 9 to the base end of the powder feeding tube 8 by the cutting motor 10 and rotates the cutting motor 11 to rotate the mold 1 with the screw.
It is a structure to throw in. Also, this powder feeder 7
Is installed on the side of the mold 1, and the tip of the powder supply pipe 8 can be moved vertically and horizontally in a plane on the mold by a moving mechanism (not shown). And can supply powder.

In such a structure, a molten steel level meter 12 for detecting the molten steel level in the mold and a powder level meter 13 for detecting the powder upper surface level are installed above the mold 1 at appropriate positions, and the mold is further molded. A camera 14 such as an infrared camera for picking up an image of the powder surface inside is installed above the mold 1 through the immersion nozzle 5. The cameras 14 are arranged in a pair in the long side direction of the mold with the dipping nozzle 5 interposed therebetween, and a total of two cameras 14 capture images of the powder surface.

Molten steel level meter 12 and powder level meter 13
The detection signal of is subjected to signal processing such as signal conversion and amplification by the detection device 15 and then input to the control device 16, and in the micro-computer of the control device 16, the powder thickness is determined from the difference between the molten steel level and the powder top level. Is calculated, and this powder thickness measurement value is used as a powder thickness representative value T (*).

The detection signals of the molten steel level meter 12 and the powder level meter 13 are arithmetically processed in the detector 15 to calculate the powder thickness representative value T (*), which is input to the controller 16. Good.

The molten steel level meter 12 is an eddy current level meter generally used for detecting conductors, and the powder level meter 13 is a laser distance meter as a general displacement sensor. If the eddy current level meter 12 is installed at a height L from the temporary reference level, the laser range finder 13 is installed at a height H from the temporary reference level, and the irradiation angle to the powder horizontal plane is θ, the powder thickness T is , Can be expressed by the following equation (1). The powder thickness obtained by this formula is shown in Fig. 2.
Is the powder thickness measurement value at any one point (*) of
It becomes the powder thickness representative value T (*).

[0027]

[Equation 1]

The image signals from the two cameras 14 are input to the image processing apparatus 17, and the microcomputer of the image processing apparatus 17 determines the detection areas as, for example, four areas A.
To D (two detection areas for one camera), and the relative powder thickness ΔT in each area A to D
_{A to} ΔT _D is obtained and output to the control device 16. here,
In the image processing device 17, the areas A to A shown in FIG.
The average brightness is calculated for each D, and each area A to D is calculated.
The average brightness of the powder is compared with the brightness reference value to calculate the powder thickness relative values (comparative thickness) ΔT _{A to} ΔT D in the respective regions A to _D. The relationship between the average brightness and the powder thickness change rate is obtained in advance, and this is used to calculate ΔT _A to ΔT _D. The image processing signal from the image processing device 17 is output to the control device 16 in the next stage, and the microcomputer of the control device 16 controls the powder thickness relative values ΔT _{A to} ΔT.
You may make it calculate _D.

In the controller 16, the powder thickness representative value T (*) calculated above and the powder thickness relative values ΔT _{A to} ΔT _D are calculated.
By calculating (proportional calculation) in combination with and, the average powder thicknesses T _{A to} T _D in the respective regions A to _D are calculated, and the powder feeder based on these highly accurate average powder thicknesses T _{A to} T _D. The amount of powder added from 7 is controlled as described later. Further, data from the process computer 18 is also input to the control device 16, the powder consumption amount is calculated as described later, and the detection result, calculation result, etc. are CR.
It is monitored by displaying it at T19.

Control of the amount of powder input from the powder feeder 7 is performed by controlling the average powder thickness T calculated for each of the areas A to D.
_{A to} T _D and preset powder thickness control target value T ₀
And the result is output to the drive device 20 of the powder feeder 7, and the cutting motors 10 and 11 of the powder feeder 7 are ON / OFF controlled for each of the areas A to D. For example, in the area A, if T _A <T ₀ , the motor 1
When an ON command is output to 0 and 11 and T _A > T ₀ ,
The powder thickness is controlled by outputting an OFF command to the motors 10 and 11. Therefore, until the average powder thickness T _A matches the powder thickness control target value T ₀ , the motors 10, 1
1 is driven or stopped, the average powder thickness T _A is maintained at the powder thickness control target value T _0, and the powder thickness during casting is controlled within an appropriate range. Here, it is necessary to set a large amount q of the powder feeding amount per unit time of the powder feeder 7 in advance so that the feeding amount is not insufficient. The above operation is performed in each area A to D in the mold.
By carrying out each time, the local lack of powder in the mold is eliminated, and the powder thickness can be automatically controlled to a constant level and evenly controlled throughout the mold.

Further, in the microcomputer of the control device 16, the motors 10 and 11 are turned on during the time when the tip of the powder supply pipe 8 of the powder supply machine 7 passes each area.
The time t _{1 at} which the powder is supplied is stored for each of the areas A to D, and this is multiplied by the preset powder supply amount q per unit time to obtain the powder supply amount Q.
_{1A to} Q _1D are obtained from the following equation (2).

[0032]

[Equation 2]

On the other hand, the slab drawing speed V _c1 and the slab casting width W ₁ are input to the microcomputer of the control device 12 from the process computer 18, and the molten steel casting amount R ₁ per unit time which changes momentarily is inputted. , Is obtained by the following equation (3).

However, T ₁ is the slab casting thickness, and ρ is the molten steel density.

[0035]

(Equation 3)

Therefore, the powder consumption amount S per unit casting amount of molten steel at an arbitrary time t is obtained by the following equation (4) for each of the regions A to D.

[0037]

(Equation 4)

However, ΣQ is the total of the powder supply amount Q _{1 at} an arbitrary time t. In this embodiment, t is 5 minutes and the powder consumption amounts S _{A to} S _D are calculated every 5 minutes.

Here, S (= S _A + S _B + S _C + S _D )
Varies depending on operating conditions, but is approximately 0.2-0.6k
Since g / t-steel is desirable, in the present embodiment, the upper limit value S _{HA to} S _HD and the lower limit value S _{LA to} S _LD of the powder consumption amount are set to the upper limit in the ideal range of the powder consumption amount S for each region. 1/4 of the value S _H and the lower limit S _H , that is, 0.0
5 to 0.15 kg / t-steel, and if the powder consumption S _{A to} S _D in each area deviates from the upper limit and lower limit, respectively, the flow of hot water in the mold or the physical properties of the powder When it is judged that something abnormal has occurred, an alarm is output (see Fig. 4) and a buzzer or lamp display is used to notify.

Further, the average powder thicknesses T _{A to} T _D calculated for each region and the powder consumption amounts S _{A to} S _D per molten steel unit casting amount are output as trends on the screen of the CRT 19 and are respectively displayed. You can know the change of the value with time.
Further, an alarm when the powder consumption amounts S _{A to} S _D described above are determined to be abnormal is also output on the screen of the CRT 19.

In the above-mentioned structure, the mold powder thickness is automatically controlled and the mold powder consumption is monitored as follows.

(1) The controller 16 compares the average powder thicknesses T _{A to} T _D in each of the regions A to _D with the powder thickness control target value T ₀ , respectively, and these T _{A to} T _D and T ₀ are compared.
If T _{A to} T _D and T ₀ match, the motors 10 and 11 are driven, and the mold powder 6 is supplied and replenished in each of the regions A to D so that the powder thickness is constant throughout the mold. Controlled. FIG. 3 shows the temporal change of the powder thickness in each of the areas A to D in the mold, which greatly increases and decreases in the conventional manual monitoring, and a large difference in the powder thickness occurs in each area. In the present invention, it can be seen that the powder thickness is kept constant and is uniformly held in each of the areas A to D.

(2) Simultaneously with the above control, in each of the areas A to D, the powder consumption amount S _A per molten steel unit casting amount every 5 minutes is calculated from the powder supply amounts Q _{1A to} Q _1D and the molten steel casting amount R _1. to S _D is calculated, as shown in FIG. 4, the powder consumption S _a to S _D is the outside the setting range of the upper limit value S _H, the lower limit S _L, warning buzzer and the display lamp, or CRT19 Alert on the screen.

Powder consumption S _A in each area A to D
By monitoring ~ _SD , changes in molten steel flow in the mold and physical properties of powder can be continuously known. A large change in powder consumption means an abnormal flow of molten steel in the mold or a change in powder properties.In the case of an abnormal flow of molten steel in the mold, lower the casting speed and blow Ar to prevent clogging of the immersion nozzle. Abnormalities can be mitigated by reducing the gas flow rate, increasing the immersion depth of the immersion nozzle, etc., and thereby adversely affecting the quality and operation can be minimized.

On the other hand, if the physical properties of the powder deteriorate, the powder consumption becomes extremely small, and if the powder is left as it is, a restraint breakout occurs due to the lack of the powder melting layer. In such a case, the casting speed is once reduced to the extent that a sufficient powder consumption amount can be secured, and the powder feeder 7
By taking measures such as renewing the mold powder 6 in No. 1 to a new lot, it is possible to prevent operational troubles such as restraint breakout.

In the above, control of the powder input amount is
The case where the powder supply drive source of the powder supply machine 7 moving at a predetermined speed is ON / OFF controlled has been described, but the present invention is not limited to this, and the movement of the powder supply machine 7 is temporarily stopped by keeping the powder input amount constant. A method may be used, or a method of controlling the powder feeding amount itself of the powder feeder 7 which moves at a predetermined speed may be used. Needless to say, the level of the mold powder is not limited to the eddy current level meter and the laser distance meter, and other level meters can be used.

[0047]

As described above, according to the present invention, the powder thickness T _n in each region is obtained from the powder thickness representative value T (*) in the mold and the powder thickness relative distribution in each region in the mold,
Based on the difference between the powder thickness T _n and the powder thickness control target value T ₀ , the powder feeding amount from the powder feeder is controlled, and the powder feeding amount and the molten steel casting amount per unit time in this control are relatively controlled. The powder consumption amount for each short time is obtained for each area, and the molten steel flow in the mold and the abnormalities in the physical properties of the mold powder are monitored based on the powder consumption amount, so that the following effects are achieved.

(1) During casting, the powder thickness distribution of each region in the mold can be quantitatively grasped, and the powder input amount can be adjusted for each region, so that the mold powder thickness can be adjusted to a predetermined level. In addition, it is possible to uniformly control the entire mold, and it is possible to reliably prevent the deterioration of the slab quality due to the local increase or decrease of the powder thickness and the restraint breakout due to the lack of the powder melt layer.

(2) During casting, it is possible to continuously obtain the powder consumption amount per molten steel unit casting amount for each region in the mold and to constantly monitor it, whereby abnormal molten steel flow in the mold such as drift and powder It is possible to prevent problems in quality and operation due to abnormal physical properties.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a powder charging device according to the present invention.

FIG. 2 is a plan view showing a movement path of a divided region in a mold and a tip end portion of a powder supply pipe by the image processing apparatus according to the present invention.

FIG. 3 is a graph showing changes over time in the powder thickness in each region in the mold, where (a) shows the conventional case and (b) shows the present invention.

FIG. 4 is a graph showing the change over time in powder consumption in each region in the mold according to the present invention.

5A is a schematic diagram showing a conventional powder feeding amount control device, and FIG. 5B is a schematic diagram showing a conventional powder feeding device.

[Explanation of symbols]

 1 ... Mold 2 ... Molten Steel 3 ... Tundish 4 ... Sliding Nozzle Device 5 ... Immersion Nozzle 6 ... Mold Powder 7 ... Powder Feeder 8 ... Powder Supply Pipe 9 ... Supply Hopper 10 ... Cutting Motor 11 ... Cutting Motor 12 ... Molten Steel Level meter 13 ... Powder level meter 14 ... Camera 15 ... Detection device 16 ... Control device 17 ... Image processing device 18 ... Process computer 19 ... CRT 20 ... Driving device

Claims (4)

[Claims] 1. The powder thickness in the mold is measured by controlling the level of the molten steel surface in the mold and the upper surface level of the powder when controlling the layer thickness of the mold powder injected from the powder feeder to the surface of the molten steel in the mold. The representative value T (*) is obtained, and the image signal from the camera installed above the mold is further processed to obtain the powder thickness relative distribution in each region in the mold. This powder thickness relative distribution and the powder thickness representative value T
The powder thickness T _n of each region in the mold is calculated from (*) and the powder thickness T _n of each region is calculated based on the difference between the powder thickness T _{n of} each region and the preset powder thickness control target value T _0. A method for controlling a mold powder thickness, which comprises controlling an amount of powder supplied from a feeder. 2. The method for controlling the mold powder thickness according to claim 1, wherein the time t ₁ during which the powder supply drive source of the powder supply machine is ON in each region in the mold and the unit time of the powder supply machine. The powder input amount Q ₁ is calculated from the powder input amount q per unit, and the powder consumption amount S per molten steel unit casting amount is calculated in the mold from the powder input amount Q ₁ and the molten steel casting amount R ₁ per unit time. Obtained for each area, and the powder consumption amount S _{n in} each of these areas
The method for controlling the thickness of the mold powder is characterized by monitoring the abnormality of the mold powder. 3. A powder feeder for feeding mold powder onto the molten steel surface in the mold, and a level meter for measuring the molten steel molten metal level and the powder upper surface level in the mold.
A camera that takes an image of the powder surface in the mold, an image processing device that processes the image signal from this camera, a representative value T (*) of the powder thickness obtained from the level detection signal, and each in-mold image obtained from the image processing signal. The powder thickness T _n of each area in the mold is calculated from the relative distribution of the powder thickness of the area, and the powder is supplied based on the difference between the powder thickness T _{n of} each area and the preset powder thickness control target value T _0. A mold powder feeding device characterized by comprising arithmetic processing control means for controlling the amount of powder fed from the machine. 4. A powder feeder for introducing mold powder onto the molten steel surface in the mold, and a level meter for measuring the molten steel surface level and the powder upper surface level in the mold.
A camera that takes an image of the powder surface in the mold, an image processing device that processes the image signal from this camera, a representative value T (*) of the powder thickness obtained from the level detection signal, and each in-mold image obtained from the image processing signal. The powder thickness T _n of each area in the mold is calculated from the relative distribution of the powder thickness of the area, and the powder is supplied based on the difference between the powder thickness T _{n of} each area and the preset powder thickness control target value T _0. The amount of powder input from the machine is controlled, and the powder supply drive source of the powder supply machine is turned on in each area in the mold.
And the time t ₁ which is a N, calculates the powder charged amount Q ₁ from the powder charging amount q per unit of powder feeder time, the molten steel casting amount R ₁ per this powder input amount Q _1, unit time From the above, the powder consumption amount S per molten steel unit casting amount is obtained for each region in the mold, and when the powder consumption amount S _n of each region exceeds a set range, arithmetic processing control means for outputting an alarm is provided. Characteristic mold powder feeding device.