JPH02247539A - Method for measuring slag thickness on molten metal - Google Patents

Abstract

PURPOSE:To improve the measurement accuracy by obtaining the fall quantity of a gas blow-in pipe from when the rise variation rate of the gas pressure in the gas blow-in pipe reaches a 1st set value to when the rise variation rate reaches a 2nd set value larger than the 1st set value as the slag thickness. CONSTITUTION:A refractory cylinder body 2 is fixed on a probe base 1. A blow-in pipe 4 which is made of refractories and fixed to the lower end of the inert gas blow-in pipe 3 is arranged in the cylinder body 2. Inert gas which is supplied to the pipe 3 is jetted from the injection port 5 at the lower end of the blow-in pipe 4. The injection port 5 is formed at a horizontal angle - an upward vertical angle to a horizontal surface. This pipe 3 is moved down toward the molten metal to detect the rise variation rate of the gas pressure in the pipe 3. The fall quantity of the pipe 3 from when the rise variation rate reaches the 1st set value to when the rise variation rate reaches the 2nd set value larger than the 1st set value is obtained as the slag thickness. The when the injection port 5 enters the slag, etc., the force of the injected gas for pressing the slag, etc., downward is small, so the fall of the slag top surface, etc., is small; and the disturbance of the slag surface, etc., is small, so a measurement becomes accurate correspondingly.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the measurement of slag thickness on molten metal.

[Conventional technology]

For example, when a measuring probe is immersed in molten steel to analyze the components in molten steel, it is necessary to immerse the probe to the required depth below the molten steel surface below the slag. It is necessary to detect the position of the molten steel surface under the slag. Also when removing molten slag in the steel manufacturing process.

It is necessary to measure or detect the amount (thickness) of molten slag.

On the other hand, in continuous casting, powder is supplied onto the molten steel in the mold, but it is necessary to measure or detect slag (molten powder) on the molten steel in order to manage powder input.

In conventional slag depth measurement, a gas jet nozzle with an open bottom end is lowered vertically and immersed into molten steel through the slag. The position of the top surface of the slag is detected from the rise of
47413). Alternatively, the electrode pair is lowered and the resistance value between the electrodes is measured, and when the resistance value reaches a value corresponding to slag, it is determined that the slag has reached the top surface, and when the resistance value corresponds to molten steel, the slag has reached the top surface. is being determined. Also,
Lower the temperature measuring element and measure the temperature change while lowering to determine the upper surface of the molten steel under the slag (Utility Model Publication No. 63-47413)
Publication No.).

[Problem to be solved by the invention]

Measuring device using back pressure (Japanese Utility Model Publication No. 63-47413)
The measurement accuracy is low because the gas jet itself for measurement disturbs the top surface of the slag and the molten steel surface, causing disturbance. This has the disadvantage of complicating the overall structure and increasing manufacturing costs. In addition, in a measuring device using a pair of electrodes, the electrodes are subject to severe melting and damage, requiring frequent replacement of the electrodes, which is disadvantageous in terms of maintenance and requires high costs for replacement parts.

Measuring device using temperature measuring element! (Japanese Utility Model Publication No. 63-47413), the wiring of the electrical leads to the temperature measuring element is complicated, the overall structure is complicated, the production cost is high, and the temperature measuring element part is subject to severe melting. There is a problem.

The present invention relates to improvements in slag thickness measurement by backpressure.

The purpose is to improve the accuracy of the tank chamber by improving the problem of the gas ejected for measurement disturbing the top surface of the slag, as described above.

[Means to solve the problem]

In the present invention, gas is supplied to a gas injection pipe made of a refractory material and has a gas injection port formed at an angle ranging from parallel to a horizontal plane to upwardly perpendicular, and the gas is injected from the gas injection port. At the same time, the gas blowing tube is lowered from above the molten metal toward the molten metal, and the rate of increase and change in the gas pressure of the gas blowing tube is detected. After the rate of increase and change reaches the first set value, the The amount of descent of the gas blowing pipe until it reaches a second set value that is greater than the first set value is obtained as the slag thickness.

[Effect]

Since the gas injection port is formed at an angle within the range of angles from parallel to the horizontal plane to upwardly perpendicular, when the gas injection port enters the slag and molten steel, the injection gas pushes the slag or molten steel downward. Since the force is small, the drop of the top surface of the slag or the top surface of the molten steel is small, and the disturbance of the slag surface or the molten steel surface is small, so the measurement becomes more accurate.

In a preferred embodiment of the present invention, in an application in which the probe is immersed to a predetermined depth from the upper surface of molten steel, the slag is measured as described above to determine the molten steel surface, and the probe is lowered from this molten steel surface to a predetermined depth.

Other objects and features of the invention will become apparent from the following description of an embodiment with reference to one drawing.

〔Example〕

FIG. 1 shows the main part of a measuring mechanism that implements the present invention in one embodiment, and FIG. 2 shows the configuration of a gas supply system and a measuring electric circuit connected thereto. It is used in a device for measuring the components of molten steel, as proposed in No. 56-201154, which generates molten steel particles from molten steel and sends them together with an inert gas to an emission spectrometer for spectroscopic analysis of the components of the molten steel particles. , used to generate molten steel particles.

A refractory cylinder 2 is fixed to the probe base 1,
Inside this cylindrical body 2, there is a blowing pipe 4 made of refractory material fixed to the lower end of the inert gas blowing pipe 3. A horizontally extending inert gas injection port 5 is opened at the lower end of the blowing pipe 4, and the inert gas supplied to the vibrator 3 is injected from this injection port 5 in the horizontal direction. In addition, this injection port 5
The angle may be any other angle within the range from the horizontal direction to the upward vertical direction.

A molten steel particle collection tube 6 passes through the probe base 1,
This collection pipe 6 sends the inert gas blown into the refractory cylinder 2 together with the molten steel fine particles generated within the cylinder 2 to an optical emission spectrometer (not shown).

The probe base 1 is supported by a support tube 7, and the support tube 7 is supported by an arm 8 of an elevating device so as to be able to move up and down. One end of a wire 9 is fixed to the lower end of the support tube 7, and the wire 9 is stretched around a pulley 10 supported by the arm 8 via a bearing and wound around a wire winding drum 11. .

The wire winding drum 11 is supported by the arm 8 via a bearing.

A switch striker 15 is fixed to the lower end of the wire 9, and an upper limit switch 16 is attached to the arm 8, which is switched from open to closed by the striker 15.

The rotation shaft of the pulley 10 is integral with the pulley 10 and rotates together with the pulley 10. This rotating shaft passes through the bearing of the arm 8, and a rotary encoder 14 is coupled to this rotating shaft, which generates one electric pulse every time the rotating shaft rotates by a predetermined minute angle.

The rotating shaft integrally fixed to the wire winding drum 11 has a
The output shaft of the reducer 12 is connected.

A rotating shaft of an electric motor 13 is coupled to an input shaft of this reducer 12 .

When the electric motor 13 is urged to rotate in the forward direction, the wire take-up drum 11 rotates clockwise, the wire 9 is rewound, and the support tube 7 is lowered accordingly. When the electric motor 13 is urged to rotate in the opposite direction, the wire winding drum 11 rotates counterclockwise to wind up the wire 9, and the support tube 7 rises accordingly. When the support tube 7 is lowered or raised in this manner, the rotary encoder 14 generates one electric pulse for each iris of the wire 9 that is lowered or raised.

Referring to FIG. 2, when lowering the support tube 7 and positioning the injection port 5 to a predetermined depth from the surface of the molten steel, the pipe 3 is equipped with a check valve 22. Adjustable throttle valve 21. Electromagnetic flow rate 1i
151 section valve 20. Solenoid switching valve 19 and flow control valve 18
Through inert gas cylinder 17 to 100m Q/w
When inert gas is supplied at a flow rate of about 1.5 in. and molten steel fine particles are generated after the injection port 5 is set at a predetermined depth from the upper surface of the molten steel, the check valve 25 and the float-type volume flow meter 24.
Flow rate control valve 23, electromagnetic switching valve 19, and flow rate control valve 18
through an inert gas cylinder 17 to 15 Q/mi
Inert gas is supplied at a flow rate of about n.

The microprocessor (hereinafter referred to as CPU) 27 includes
Key interface 28. Display controller 30. Sensor interface 32, 35, solenoid driver 33 that energizes the electromagnetic flow control valve 20 with a current of a value specified by digital data, and a solenoid driver 33 that turns on/off the electromagnetic switching valve 18.
Off-energizing solenoid driver 34. A sensor interface 35, a motor driver 36, and a lamp driver 41 are connected, and the CPU 27 performs predetermined control operations and signal processing operations in response to the operation of the key switch 29.

Figures 3a, 3b and 3c show the control operations of the CPU 27. When it is powered on (step 1; hereinafter the word step is omitted in parentheses), the CPU 27 controls the output port. Set the output signal during standby, clear internal registers, flags, counters, etc., and set the lowering amount control limit value register DSL, first rate of change set value register FDS, second rate of change set value SDS, and immersion depth. A standard value preset in the program is written in the value register SDP (2), and the operation of the key switch 29 is waited for.If there is human power on the numeric keypad, the key-in input is read and written to the register.

In other words, after the first key * press, there is a numeric keypad manual input, and when the second key * is pressed, the numeric keypad manual input data during that time is updated and written to the lowering amount limit value register DSL, and the numeric keypad manual input is performed next. When there is a third key * input, the manual input from the numeric keypad is transferred to the first change rate setting value register FD.
Update is written to S, and then when there is a numeric keypad input and the fourth key * is input, the numeric keypad input is updated to the second change rate setting value register SDS. When the number of times the key * is inputted, the manual input of the numeric keypad is updated and written to the immersion depth register SDP, and the number of times the key * is inputted register is cleared (3 to 5).

When the key-in reading (3) reads that the start key STA is on (3, 4, 6), it is checked whether the upper limit switch 16 is closed (the support cylinder 7 is in the upper retracted position) (7).

If it is not closed, the motor 13 is urged to rotate in the opposite direction (8).
Drive the support cylinder 7 upward and enable interrupt processing (9)
, when the switch 16 is closed, the motor 13 is stopped (10, 11). Note that if the key switch 29 is operated while the motor 13 is energized to rotate in the reverse direction, the motor 13
Stop and return to key-in reading (3) (10, 12, 1
3).

When the switch 16 is closed, or when it is closed and the reverse rotation of the motor 13 is stopped, the electromagnetic switching valve 19 is energized, and the switching valve 19 is connected to 18-20 (14) and the pressure setting (15). ). In this pressure setting (15), the detected pressure of the pressure gauge 26 is digitally converted and read, it is checked whether it is within the set range, and if it is below the set range, it is sent to the electromagnetic flow control valve 20. Increase the energizing current value by one step, and lower it by one step when it is on the upper side.

Read the detected pressure of the pressure gauge 26 again, and repeat this until the detected pressure falls within the set range.

When the pressure detected by the pressure gauge 26 falls within the set range, the motor 13
16) to drive the support tube 7 downward by energizing it in the forward rotation, enable interrupt processing (17), wait for the upper limit switch 16 to change from closed to open, and while waiting, the lowering amount register It is checked whether the content DSR of DSR (the amount of descent of the support cylinder 7) is equal to or greater than the content DSL (the amount of descent limit value) of the amount of descent limit value register DSL (18.19). DSR is DS
When the value is equal to or higher than L (switch 16 is abnormal), the process proceeds to step 8.

Now, when the upper limit switch 16 switches from closed to open,
Since this is used as the reference point for measuring the amount of descent of the support cylinder 7, the amount of descent register DSR is cleared here (initialization: content data indicates zero).

Here, an overview of the interrupt processing of the CPU 27 will be explained.

The rotary encoder 14 generates one pulse every time the support tube 7 moves 1m111 (descending or rising), and this pulse is sent to the CPU 2.
7, and each time this pulse arrives at the interrupt port INT while interrupts are enabled, the CPU 27 proceeds to the interrupt processing (60) shown in FIG. 3c, where the motor When the motor 13 is urged to rotate in the forward direction (the support cylinder 7 is lowered), the lowering amount register DSR is incremented by 1 (updated to a value that shows the current content plus 1), and the motor 13 is urged to rotate in the reverse direction. (When the support cylinder 7 is rising), set the descending amount register DSR by 1 decrement (
(Update to the current content minus 1).

Therefore, the motor 13 is energized to rotate normally (16) and the interrupt is enabled (17), and the lowering amount register DSR is cleared when the upper limit switch 16 changes from closed to open (19).
), and hereinafter, the content DSR of the descent amount register DSR is the amount of descent (ms) of the gas injection port 5 from the position of the gas injection port 5 (upper reference point) when the striker 15 leaves the upper limit switch 16. It will be shown.

Returning to the main routine (Fig. 3a) again to continue the explanation, when the descent amount register DSR is cleared (19), the CP
U27 starts a timer dt that times out after the elapse of time d (20), and sets the detected pressure Ps of the pressure gauge 26.
(21) and calculate its rate of change dPs (22)
). That is, the previous detected pressure read value is subtracted from the current read value to obtain this as a rate of change, and the current read value is updated and written in the previous detected pressure register. And display the current detected pressure Ps on the display 31a23)
, displays the current rate of change on the display 31b (24
).

Referring to FIG. 3b, the CPU 27 then determines the rate of change dP
s, the first rate of change set value FDS and the second rate of change SDS
Compare with (25.32). Reference is now made to FIG.

When lowering the gas injection port 5 into molten steel, the gas injection port 5
The back pressure, that is, the pressure detected by the pressure gauge 26 shows changes as shown in FIG. The first change rate set value FDS is for determining whether the pressure change rate dPs is the change rate when the gas injection port 5 is in a slag layer or molten steel, and the second
The change rate setting value SDS is for determining whether the change rate is the same as when the steel is in molten steel.

When the calculated rate of change dPs is less than FDS, the CPU 27 ``turns off the slag immersion indicator lamp 30''.
, clears the slag immersion flag SF (31). dPs
When the value exceeds FDS, turn on the slag immersion indicator lamp 38 (26), write 1 (slag immersion) to the slag immersion flag SF (2g), and set the slag top surface position register S.
The contents of the drop amount register DSR at that time are written into DR (29).

When the calculated rate of change dPs is less than SDS, the molten steel immersion indicator lamp 39 is turned off (33), and the molten steel immersion flag I is turned off.
Clear F (31). When dPs becomes SDS or more, turn on the molten steel immersion indicator lamp 39 (38), write 1 (molten steel immersion) to the molten steel immersion flag IF (40),
Write the contents of the drop amount register DSR at that time to the molten steel top surface position register SSR (41), and
slag thickness) on the display 31e42),D
SR-3SR (immersion depth of the gas injection port 5 from the upper surface of the molten steel) is displayed on the display 43 (43). After the gas injection port 5 is immersed in the molten steel, the immersion depth DSR in the molten steel is
- Checks whether the SSR has reached the set depth SDP (contents of the immersion depth set value register SDP) (44), and when it has reached it, stops the motor 13 (stops the descent of the gas injection port 5). When the timer dt times out while lowering the gas injection port 5 to the set depth SDP, the process returns to step 20, starts the timer dt again, reads the pressure Ps (35-20), and calculates the rate of change dPs. (22) As the operation is repeated, the detected pressure Ps of the pressure gauge 26
is read in the same period as dt, and the pressure change rate dPg is updated in the same period as dt.

Furthermore, if an input is made by the key switch 29 while reading the detected pressure repeatedly in this way (36), the motor 13 is stopped (37) and the process corresponding to the key manual operation is executed (4-
5 or 4-6-50).

Now, when the immersion depth of the gas injection port 5 in the molten steel reaches the set value SDP, the motor 13 is stopped (44-45).

The CPU 27 turns on the ready lamp 40 (46).
.

Turn off the power to the electromagnetic switching valve 19 and switch the switching valve 19 to 18-23.
As a connection (47), it waits for input of the key 29.

In this state, the gas injection port 5 is located at a depth of SDP from the top surface of the molten steel, and inert gas is blown into the molten steel at a flow rate for generating molten steel fine particles from the gas injection port 5. are introduced into an emission spectrometer (not shown) through the collection tube 6, and the spectrometer analyzes the components of the molten steel particles.

The operator presses the stop key STP of the key switch 29 to end this measurement, presses the down key Md to increase the depth of the gas injection port 5, and presses the up key Mu to leave the depth of the gas injection port 5.

When the stop key STP is pressed, the CPU 27 energizes the motor 13 to reverse rotation (49), turns off the lamps 38 to 40 (SO), and energizes the electromagnetic switching valve 19 to close the switching valve 19.
as 18-20 connection (51), key-in reading (3)
Proceed to.

When the down key Md is pressed, the CPU 27 urges the motor 13 to rotate in the forward direction while the down key Md is pressed (52.53).
), when the up key Mu is pressed, the motor 13 is urged to rotate in the reverse direction while it is pressed (55°56).

The details of the interrupt processing will be further explained with reference to FIG. 3c again.

Every time the rotary encoder 14 generates one pulse, the third
Proceeding to the interrupt process in Figure c, while the motor 13 is being energized to rotate in the forward direction, the contents of the drop amount register DSR are incremented by 1 and the updated value is displayed on the display 31d.61-63
), the content DSR of the drop amount register DSR is the set limit value D
Check whether it is above the limit value DSL (64), and if it is above the limit value DSL, stop the motor 13 (65).
If it is not SL, the contents of the flag register IF are checked (66), and if it is 0 (not immersed in molten steel), the process returns to the main routine. When the content of the flag register IF is 1 (molten steel immersed), the molten steel top surface position register SS is determined from the content DSR of the drop amount register DSR.
Subtract the contents of R and write the obtained value to the immersion depth display register DIR in molten steel (67), and set the immersion depth DIR.
is displayed on the display 31c (6g), the detected pressure Ps of the pressure gauge 26 is read (69), the detected pressure Ps is displayed on the display 31a (70), and the process returns to the main routine. As described above, when the motor 13 is urged to rotate in the forward direction, the support tube 7 is lowered, and the gas injection port 5 is immersed in molten steel (IF=1), the rotary encoder 14 emits one pulse. Each time, the display 31d displays the amount of descent, the display 31c displays the immersion depth in molten steel, and the display 31a displays the pressure.

When the motor 13 is energized to rotate in reverse, the lowering amount register DSR
Decrement the contents by 1 and display the updated value on display 3.
1d (61, 71, 72), check whether the upper limit switch 16 is closed (73), and when it is closed, stop the motor 13 (74). checks the contents of the flag register IF (75) and if it is 1 (dipping in molten steel),
Subtract the contents of the molten steel top surface position register SSR from the contents of the drop amount register DSR DSR, and write the obtained value to the molten steel immersion depth display register DIR (76), D
Check whether IR is below O (77), and if it is below O, rewrite DIR to zero and clear register IF 79), turn off indicator light 39.40 80.81), and set immersion depth DIR. Display on display 31c (6g)
, and reads the detected pressure Ps of the pressure gauge 26 (69),
Displaying the detected pressure Ps on the display 31a (70),
Returning to the main routine 6 Due to the steps above, the motor 13 is urged to rotate in the opposite direction, the support cylinder 7 is raised, and the gas injection port 5 is
is immersed in molten steel (IF=1), each time the rotary encoder 14 emits one pulse, the display 31d displays the amount of descent, the display 31c displays the immersion depth in the molten steel, and the display 31a displays the pressure. is updated, and when the gas injection port 5 rises to the surface of the molten steel, the 1 indicator lights 39 and 40 are turned off and the contents of the flag register IF become O.

After IF becomes O while the motor 13 is energized to rotate in the reverse direction, in the 1st interrupt processing (60), steps 61-71-
72-73-75-82, flag register SF
Check the content of , and if it is 1 (gas injection port 5 is in the slag), drop amount register DSR
Checks whether the content DSR becomes less than the content SDR of the slag top surface position register SDR, and if it becomes less than the content (the gas injection port 5 rises above the slag layer), the slag top surface position register SDR is cleared ( 84), clear the flag register SF 86), turn off the slag immersion lamp 38 (87), display the contents (zero) of the register SDR on the display 31e (88), and return to the main routine.

After that, update the contents of the descent amount register DSR and update the display 31d.71-72-73-7
5-82-Return), and when the upper limit switch 16 is closed, the motor 13 is stopped (73-74).

By the operation of the CPU 27 explained above, the operator can input the descending amount limit value DSL, the first
Input the change rate set value FDS, the second change rate set value SDS, and the immersion depth in molten steel SDP, and then press the start key ST.
When P is pressed, the support cylinder 7 is driven upward when the upper limit switch 16 is open, and the upward movement of the support cylinder 7 is stopped when the switch 16 is closed. When the upper limit switch 16 is closed or closed, the electromagnetic switching valve 19 is connected to 18-20, and the electromagnetic flow control valve 20 is opened so that the pressure detected by the pressure gauge 26 falls within the set range. The degree is adjusted. When this adjustment is completed, the support cylinder 7 is driven downward, and the position of the gas injection port 5 (upper base position W) when the upper limit switch 16 is changed from closed to open is set to zero (lowering amount register DSR = 0). Counting of the amount of descent is started, and the amount of descent is displayed on the display 31d. Also d
t The detected value Ps of the same cycle pressure gauge 26 is read, the pressure change rate dPs is calculated, and the detected value Ps is displayed on the display 31.
In a, the rate of change is displayed on the display 31b.

When the gas injection port 5 reaches the slug top surface position due to this downward drive and the detected value of the pressure gauge 26 shows a change greater than or equal to the first rate of change set value FDS, the amount of descent DSR at that time is written to the slug top surface position register SDR. The indicator light 38 lights up. After that, the detected value of the pressure gauge 26 becomes the second rate of change set value SDS.
When the above changes are indicated, the drop amount DSR at that time is written in the molten steel top surface position register SSR, the indicator light 39 lights up, the slag thickness 5SR-8DR is displayed on the display 31e, and the gas injection port 5 The immersion depth in molten steel DSR-3SR is displayed on the display 31c.

When the immersion depth DSR-8SR of the gas injection port 5 in the molten steel reaches the immersion depth set value SDP, the downward drive of the support cylinder 7 is stopped and the electromagnetic switching valve 19 is switched to the 18-23 connection. This state is the setting for molten steel component analysis, and the CPU 27 waits for input from the key switch 29 in this state. When the operator wants to adjust the depth of the gas injection port 5, the operator presses the up key Mu or the down key Md. While these keys are pressed, the gas injection port 5 rises or descends, thereby causing the display 31 to The displayed value changes (Figure 3C).

When the operator presses the stop key STP after completing the analysis of the components in molten steel, the support tube 7 rises and the lamps 38 to 4
0 goes out, the electromagnetic switching valve 19 switches to the 18-20 connection (48-51), and when the upper limit switch 16 closes, the support tube 7 stops (61, 71, 72, 73, .
74).

In the above embodiment, the slag top surface position, slag thickness, molten steel top surface position, and immersion depth in molten steel are calculated by measuring the amount of descent of the gas injection port 5. The slag thickness and the immersion depth of molten steel may be calculated based on, for example, the rate of change in detected pressure dP.
Detected pressure Ps when s reaches the first change rate setting value FDS
l and the detected pressure Ps when the second rate of change set value SDS is reached.
2 difference ps2-Ps1 is converted into a depth (thickness) value based on the slag specific gravity (about 3), and the detected pressure Pss-Ps2 during molten steel immersion is converted based on the molten steel specific gravity (7, 86). Convert to depth (molten steel immersion depth) value. An experiment was conducted under the above measurement conditions to compare the slag thickness with a conventional method in which gas is jetted downward, and the result was 50.48°50° for the present invention and 40.32°50° for the conventional method. These results also prove that the present invention, in which gas is blown out horizontally, can accurately measure the slag thickness.

〔Effect of the invention〕

As described above, in the present invention, the gas injection port (5) is formed at an angle within the angle range from parallel to the horizontal plane to upward perpendicular, so that the gas injection port (5) enters the slag and molten steel. At this time, since the force of the propellant gas pushing the slag or molten steel downward is small, the drop of the top surface of the slag or the top surface of the molten steel is small, and the disturbance of the slag surface or the molten steel surface is small, so that all measurements thereof are accurate.

[Brief explanation of drawings]

FIG. 1 is a drawing showing a mechanical part of an apparatus configuration for carrying out one embodiment of the present invention, and shows an outline of a support mechanism and a lifting mechanism for a refractory cylinder 2. FIG. FIG. 2 is a block diagram showing an outline of the configuration of a gas supply system for supplying inert gas to the pipe 3 shown in FIG. 1, an electric drive system for the lifting mechanism, and a lifting position display system. FIGS. 3a, 3b, and 3c are flowcharts showing the control operation of the microprocessor 27 shown in FIG. FIG. 4 is a graph showing changes in the pressure detected by the pressure gauge 26 shown in FIG. 1 Nibrob base 2: Refractory cylinder 3: Inert gas blowing pipe 4: Blowing pipe 5: Gas injection port 6: Collection pipe 7: Support cylinder
8: Arm 9: Wire 10
:Booley 11: Wire winding drum 12: Reducer 13: Electric motor 14: Rotary encoder 15 Striker 16: Upper limit switch 17: Inert gas cylinder 1
B=Flow rate flow valve 19: Solenoid switching valve 20
: Flow rate control valve 21: Variable throttle valve 23: Flow rate control valve 25: Check valve 27: Microprocessor 22: Check valve 24: Float type volume flow meter 26: Pressure gauge ° 瑣shi Danjima old station σ (mm)

Claims (1)

[Claims] While supplying gas to a refractory gas injection pipe having a gas injection port formed at an angle ranging from parallel to upward perpendicular to a horizontal plane, the gas is injected from the gas injection port. , the gas blowing pipe is lowered toward the molten metal from above the molten metal, the rate of increase and change in the gas pressure of the gas blowing pipe is detected, and after the rate of rise and change reaches the first set value, the first
A method for measuring slag thickness on molten metal, wherein the amount of descent of the gas blowing pipe until reaching a second set value that is larger than the set value is obtained as the slag thickness.