JPH0451265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a control device for a tilting tapping induction furnace that controls the amount of hot water tapped by tilting.

[Prior Art] As a method for continuously supplying molten metal to a tundish or a mold, there are the following methods. Firstly, there is a method using a pressurized pouring furnace, in which the surface of the molten metal is pressurized so that the molten metal is poured out of the pouring spout. Although this method allows accurate control of the amount of molten metal, the equipment is expensive, and it is not suitable when the amount of molten metal is small. Second, there is a stopper rod method in which the bottom of the furnace body is opened and the hot water is tapped downward. This method simplifies the structure of the movable part, but there is a problem with the lifespan of the stopper itself.
Additionally, there is a drawback that the amount of melted metal varies depending on the level of the molten metal. Thirdly, there is a tilting tapping control method in which hot water is tapped by tilting the furnace itself. Although this method has the following problems, it allows for a cheaper system configuration compared to the above two methods. Various improvements have been made in the past regarding this method of controlling the tilting tap tap.

The first problem is that the amount of hot water that comes out varies greatly depending on the tilt angle of the furnace body. To solve this problem, for example, the "control device for metal melting furnace" disclosed in Japanese Patent Application Laid-open No. 59-133969 has developed a method that uses the tilting angle of the furnace body as a variable to calculate the tilting angular velocity of the furnace for quantitative tapping. This can be solved by calculating the following and controlling the angle of the furnace body based on this calculated data.

The second problem is that the minimum tapping speed is restricted due to the structure of the equipment, the temperature drop of the molten metal at the tapping opening, or the operation of the furnace tilting cylinder, and the cylinder speed is 0.1
If the tapping speed is approximately 200g/sec or higher in mm/sec, continuous tilting taping is possible, but in the case of minute taping below this minimum taping speed, conventionally short tilting and reversal steps were performed in short periods. A device for repeated batch tilting control was required.

[Problems to be Solved by the Invention] However, even with such a device that performs batch tilting control, the molten metal surface may rise due to the pinch force from the induction heating coil that acts on the molten metal during induction heating. In such cases, there was a problem in that it became difficult to dispense hot water in a fixed amount.

In addition, in this type of tilting tap induction furnace, the tilting speed of the tilting tap induction furnace is relatively slow so that the amount of tapped metal can be accurately controlled, so when the tilting tap induction furnace is in a stationary state, the tap There was also the problem that it took a long time to complete the process.

[Means for Solving the Problems] A control device for a tilting induction tapping furnace according to the present invention includes a tilting tapping induction furnace that taps molten metal by tilting, a drive device for tilting the tilting tapping induction furnace, and a control device for tilting the tilting induction tapping furnace. an angle detection means for detecting a position angle of a tapping induction furnace; and a tilting operation for switching a tilting speed by the drive device to high speed or low speed according to the position angle detected by the angle detection means when the tilting tap tap induction furnace is tilted by the drive device. a speed switching means, a tapping detection means provided in a tapping section of the tilting tapping induction furnace for detecting tapping; At this time, the molten metal is tilted at the tilting speed determined by the tilting speed changing means by the molten metal amount detection means that outputs a tapping command signal until the molten metal recovers to a predetermined level, and by the driving means in response to the tapping command signal. Control means for starting the tilting of the tapping induction furnace and tilting the tilting tapping induction furnace in reverse for a predetermined period of time when the tapping detecting means detects tapping or when the amount of molten metal recovers to a specified level.

[Function] According to the above configuration, when the molten metal discharged from the tilting molten metal induction furnace tilted by the drive device is detected by the molten metal discharge detection means, or when the amount of molten metal received in the tundish or mold has recovered to the specified level. At this time, the control means performs a control in which the tilting operation of the tilting tapping induction furnace is tilted in the reverse direction for a predetermined period of time and then the tilting operation is repeated again, thereby making it possible to cut out a small amount of the molten metal. Further, when the tilting tapping induction furnace is tilted by the drive device, the tilting speed is switched between high speed and low speed depending on the position angle of the tilting tapping induction furnace detected by the angle tilting means at this time. Even when the position angle is close to 0°, it can be tilted at high speed until just before hot water is tapped, reducing the time it takes to tap the hot water.

[Embodiment] FIG. 1 shows an embodiment of the control device of the present invention.

Reference numeral 1 denotes a tilting tapping induction furnace that performs batch control, and has a gutter-shaped tapping nozzle 20 at the upper end of the furnace.
A tundish 2 receives the molten metal from the tilting induction furnace 1, and a load cell 3 for detecting the weight of the tundish 2 is provided at the bottom of the tundish 2. The detection signal from the load cell 3 is sent to the tundish 2 via a conversion circuit LCT that converts the signal from the load cell 3 into an appropriate signal.
The signal is sent to the level determination circuit 4 as a signal representing the weight of the molten metal inside. This conversion circuit LCT converts the output signal of the load cell 3 into a weight signal having a scale suitable for a signal representing the weight of the molten metal minus the weight of the furnace itself, and also converts the output signal of the load cell 3 into a weight signal having a scale suitable for the signal representing the weight of the molten metal minus the weight of the furnace itself. Signals UL and LL representing the weight of the molten metal at are applied to the level determination circuit 4. In the level determination circuit 4, the weight signal of the molten metal in the tundish 2 is compared with the highest and lowest level molten metal weight signals UL and LL,
Depending on whether the molten metal level is below the minimum level or above the maximum level, a tilting start signal LO or a reverse tilting signal UO is sent to the control device 5.

Reference numeral 6 denotes a hydraulic pump unit that drives a hydraulic cylinder 1a that tilts the tilting tapping induction furnace 1. 7
is a switching valve provided in the hydraulic system, and by the operation of this switching valve 7, the direction of oil flow to the hydraulic cylinder 1a is reversed, and the tilting tapping induction furnace 1 is moved to the shaft 30 as shown in FIG. It tilts or reversely tilts in the direction of arrow K-K' with K as a fulcrum.
8 is a high/low speed switch for switching between high-speed and low-speed tilting; when switched to low-speed control, the oil sent out from the hydraulic pump unit 6 is transferred to the hydraulic flow rate adjustment valve 9;
The flow rate is now narrowed down. These switching valves 7 and high/low speed switching device 8 are controlled by control signals from the control device 5.

Further, a group of limit switches 1b are provided so as to be turned on sequentially as the tilting tap induction furnace 1 is tilted, and the state of the limit switch group 1b is read by the angle detection circuit 10, thereby controlling the tilting tap induction furnace 1. Tilt angle is detected. Note that a rotary encoder whose output varies linearly with the tilt angle is more suitable for angle detection, but in this system, a limit switch is used instead due to cost considerations.

Further, a sensor S for detecting tapping is provided in the tapping section of the tilting tapping induction furnace 1, and a detection signal from the tapping sensor S is sent to the molten metal cutting detection circuit 11.
is processed and output as a tilting control signal.
The configuration of this detection sensor S section is shown in FIG.

A first sensor S1 made of a conductor is located at the tap inlet position 21 of the gutter-shaped tap nozzle 20 provided at the upper end of the tilting tap induction furnace 1, and a second sensor _S1 made of a conductor is placed at the tap outlet position 22 of the tap nozzle 20. Sensor S ₂ in position
An electrode 1c is provided on the bottom surface of the tilting tapping induction furnace 1 to be in contact with the molten metal. Relays R ₁ and R ₂ are connected via a power source E between this electrode 1c and the sensors S ₁ and S ₂ , respectively.
When the molten metal comes into contact with the sensor S ₁ or S ₂ during tapping, conduction occurs between the electrode 1c and the sensor S ₁ or between the electrode 1c and the sensor S ₂ , and the reel R ₁ or R ₂ is turned on. The operating state of the relay is taken into the molten metal cutting detection circuit 11. In this way, since the sensors S ₁ and S ₂ detect the molten metal by coming into contact with the molten metal, it is possible to eliminate malfunctions that occur with capacitance type sensors due to the influence of carbon.

The tilting control signal and the angle detection signal from the angle detection circuit 10 are input to the reverse tilting time setting circuit 12 after cutting out the molten metal, and from the circuit 12 setting the reverse tilting time after cutting out the molten metal, the signal is sent to the control circuit 5. Then, a reverse rotation position control signal is sent out.

Next, the operation of the above device will be explained.

If the level determination circuit 4 determines that the molten metal in the tundish 2 is below the minimum level, a tilting start signal LO is sent to the control circuit 5. At this time, if the tilting angle detected by the angle detection circuit 10 is 0° or less than a predetermined angle, the high/low speed switch 8 selects the high speed side, but even if the tilting angle of the tilting tap induction furnace 1 is greater than the predetermined angle. For example, the high/low speed switch 8 selects the low speed side. this is,
This is because when the tilting tapping induction furnace 1 is initially in a stationary state, it is tilted at high speed to shorten the time required to tilt it to a predetermined angle.

Now, the tilting tapping induction furnace 1 is tilted at high speed or low speed, and the tapping nozzle 20 is tilted at a predetermined angle or more.
When the tap outlet 22 rotates below a predetermined position, the molten metal flows through the tap nozzle 20 and taping starts. When this tapped molten metal contacts the sensor _S1 installed at the tapped inlet position 21, a relay is activated.
When _R1 is turned on and the start of hot water supply is detected, the first
After the molten metal is cut out, the tilting control signal is sent to the reverse tilting time setting circuit 12. At this time, if high-speed tilting is selected, the high/low speed switch 8 is switched to the low speed side by a control signal from the control device 5.

Next, when the molten metal contacts the sensor S ₂ provided at the outlet 22 of the tap nozzle 20, the relay is further activated.
When _R2 is turned on, the molten metal cutting detection circuit 11
The timer _T1 in the control device 5 is activated by outputting the second tilting control signal from the second tilting control signal. When the timer T ₁ counts up a predetermined time, a switching signal is sent from the control device 5 to the switching valve 7 and the tilting tapping induction furnace 1 is tilted in the reverse direction.
T ₂ is activated. When the tapping from the tapping nozzle 20 stops due to the reverse tilting of the tilting tapping induction furnace 1, a switching signal is sent from the control device 5 to the switching valve 7 by counting up the predetermined time set by the timer _T2 . Then, the tilting tapping induction furnace 1 begins to tilt again. The waiting time until the reverse tilting set by timer _T1 is a value that is preset according to the amount of molten metal flowing out.
The time set by _T2 is arbitrarily set depending on the cutting condition of the molten metal and the condition of the lining.

The dispensing of hot water by such tilting and the stop of dispensing by reversing the tilting are repeated, and during this time molten metal is accumulated in the tundish 2, and when the maximum level is reached, the level judgment circuit 4 outputs a signal UO indicating the reverse tilting. be done. As a result, a signal is sent from the control device 5 to the switching valve 7 to cause the tilting tapping induction furnace 1 to tilt in the reverse direction. As in this case, when a command for reverse tilting is issued based on the level determination circuit 4, the timer _T2 does not operate, and the attitude of the tilting tapping induction furnace 1 is restored, and the angle detection circuit 10 As a result of this detection, the operation of the hydraulic pump unit is stopped when the tilt angle reaches 0°.

After that, due to the hot water coming from Tandaitsuyu 2,
When the molten metal level falls below the minimum level, similar control as described above is repeated.

As explained above, since the tilting speed of the tilting tapping induction furnace 1 is set in two stages and is switched to high or low speed depending on the position angle of the tilting tapping induction furnace 1, the tilting time until tapping is shortened, and When molten metal is detected by the sensor _S2 installed in the tapping section, the tapping operation is temporarily stopped by the tilting motion, and then the pouring by the tilting motion is repeated again, making it possible to dispense hot water in a precise amount.

As shown in FIG. 3 as a tilting tap induction furnace, an induction heating coil 40 is provided on the outer periphery of the furnace body 1 made of a refractory material, and a conductive graphite crucible 41 is provided along the inner periphery of the furnace body 1. It may be provided.

With this configuration, the induction heating coil 4
Graphite crucible 41 by alternating current power applied to
An induced current flows through the graphite crucible 41 itself, and the molten metal inside the graphite crucible 41 is indirectly heated. This results in
The induction furnace current flowing through the molten metal is reduced by that amount, and the pinch force generated in the molten metal is also reduced, so it is possible to suppress the molten metal from flying out due to the rise of the molten metal surface, and the amount of tapped metal can be accurately controlled. The operation of the sensors S ₁ and S ₂ and the method of controlling the tilting of the furnace during tapping are the same as those described in the embodiment shown in FIGS. 1 and 2.

In addition, as a means for detecting hot water, instead of the above-mentioned sensor, a sensor provided in the tundish 2 or a load cell 3 for detecting the weight of the tundish 2 is used to detect the hot water, and the tilting tapping induction furnace 1 is tilted in the reverse direction. Good too.

[Effects of the Invention] According to the present invention, when molten metal tapped by tilting is detected, the tilting tap induction furnace is temporarily tilted in the reverse direction, and then the tapping by the tilting operation is repeated again. Even when the molten metal inside rises due to pinch force or movement of the molten metal, it is possible to cut out the molten metal in fixed quantities. Further, when the tilting tapping induction furnace is tilted by the drive device, the tilting speed is switched between high speed and low speed depending on the position angle of the tilting tapping induction furnace detected by the angle tilting means at this time. Even when the position angle is close to 0°, it can be tilted at high speed until just before hot water is tapped, shortening the time until hot water is tapped.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of a control device for a tilting tapping induction furnace of the present invention, FIG. 2 is a sectional view showing details of the sensor section in FIG. 1, and FIG. 3 is a diagram showing another embodiment. FIG. 1...Tilting tapping induction furnace, 2...Tundaishu, 3
...Load cell, 4...Level judgment circuit, 5...Control device, 6...Hydraulic pump unit, 7...Switching valve,
8...High/low speed switch, 9...Hydraulic flow adjustment valve,
10... Angle detection circuit, 11... Molten metal cutting detection circuit, 12... Reverse tilting time setting circuit after cutting out molten metal,
20...Tap nozzle, 40...Induction coil, 41...Graphite crucible, 1a...Hydraulic cylinder, 1b...Limit switch group, 1c...Electrode, LCT...Zero adjustment/span adjustment circuit, _S1 , _S2 ...Sensor, _R1 , R ₂ ...Relay, T ₁ ,
T ₂ ...Timer.

Claims (1)

[Scope of Claims] 1. A tilting tapping induction furnace for tapping molten metal by tilting, a driving device for tilting the tilting tapping induction furnace, an angle detecting means for detecting a position angle of the tilting tapping induction furnace, and a tilting speed switching means for switching the tilting speed of the drive device to high or low speed according to the position angle detected by the angle detection means when the tilting tapping induction furnace is tilted by the driving device; and a tilting speed switching means provided in the tapping section of the tilting tapping induction furnace and when the amount of molten metal received from the tilting molten metal induction furnace into the tundish or mold falls below a predetermined level, a tapping command signal is sent until the molten metal recovers to a predetermined level. and a molten metal amount detection means for outputting the melt amount, and upon receiving the tapping command signal, the driving means starts tilting the tilting tapping induction furnace at the tilting speed determined by the tilting speed changing means, and the tapping sensing means A control device for a tilting tapping induction furnace, comprising: control means for tilting the tilting tapping induction furnace in reverse for a predetermined period of time when tapping is detected or when the amount of molten metal has recovered to a prescribed level. 2. The control device for a tilting tapping induction furnace according to claim 1, wherein the tapping detection means provided in the tapping section detects molten metal by directly contacting the molten metal. 3. The control device for a tilting tapping induction furnace according to claim 1, wherein the tapping is detected by a molten metal amount detection means.