JPS6257741A - Method for adjusting position of molten metal level for pressure type continuous casting method - Google Patents

Abstract

PURPOSE:To continuously cast a casting material having good quality with a pressure type continuous casting method by permitting the easy and exact adjustment of the position of a molten metal level and adjusting the molten metal level in such a manner as to prevent the intrusion of foreign matter into a molten metal during casting. CONSTITUTION:The pressure type continuous casting method consists in continuously pulling up the molten metal 2 stored in a crucible 1 contained in a pressurizing chamber 12 through a nozzle mold 6 inserted from the outside into the chamber 12, thereby casting continuously the casting material 15. The casting speed of the material 15 pulled up through the mold 6 is detected by a sensor 16 in a method for adjusting the position of the molten metal surface 3. The level falling speed of the molten metal 2 is then calculated from the casting speed by a controller 17 electrically connected to the sensor 16. A driving signal corresponding to the molten metal level falling speed is fed to a pulse motor 18. The motor 18 raises the crucible 1 at the raising speed conforming to such molten metal level falling speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention continuously casts a casting material by continuously pulling up molten metal from a crucible housed in a pressurized chamber through a nozzle mold. This invention relates to a method for adjusting the level of molten metal in a pressurized continuous casting method.

[Conventional technology]

Conventionally, for example, as a method of casting materials for producing electronic components made of copper and copper alloys in an inert gas atmosphere,
For example, a crucible is provided in a pressurized chamber filled with 0.3 to 0.5 atm of inert gas such as argon, and the molten metal stored in the crucible is poured into the pressurized chamber from above the pressurized chamber. A pressurized continuous casting method is known in which a cast material is produced by continuously pulling up a material through a nozzle mold that is airtightly inserted into the mold, cooling it, and rolling it.

In such a continuous casting method, the level, or height, of the molten metal in the crucible changes constantly during operation, so it is necessary to maintain it at a constant position to perform stable casting work. In order to ensure uniform quality of casting materials, methods for adjusting the level of molten metal as shown in Figures 2 to 4 have been proposed.

First, in the method shown in FIG. 2, the hot water level position 3 of the molten metal 2 in the crucible 1 is monitored by the ITV camera 4 and the monitor television 5, and the hot water level position relative to the nozzle mold 6, which is displayed on the monitor television 5, is determined by a predetermined value. When the crucible l is lowered from the crucible position, the crucible l is pushed up to a predetermined position to keep the level of the melt constant.The method shown in FIG. The second electrode 8 is immersed in the molten metal 2 so as to reach the bottom of the nozzle mold 6, while the second electrode 8 is attached to the water-cooled jacket 10 of the nozzle mold 6 such that its tip 8a maintains a constant position with respect to the lower end surface position of the casting nozzle 6. The tip 8a of the electrode 8 is immersed in the molten metal near the surface of the molten metal, and a voltage is applied between the electrodes 7 and 8. During operation, the tip 8a of the electrode 8 decreases as the molten metal 2 decreases.
When it leaves the molten metal surface 3, the current flowing between these electrodes via the molten metal 2 is cut off, so the presence or absence of this current is detected by the meter 9, and if the current stops flowing, then the current flows again. The crucible 1 is pushed up until the current is conducted to keep the molten metal level 3 constant, and as shown in FIG.
1, the amount of descent of the molten metal level 3 is calculated from the amount of decrease in the weight of the molten metal 2, and the crucible 1 is pushed up according to the level lowering machine to keep the position of the molten metal level 3 with respect to the nozzle mold 6 constant. We also thought of ways to preserve it.

[Problem that the invention seeks to solve]

However, in the hot water level position adjustment method shown in Figure @2 above, I
Since the mounting position of the TV camera 4 is restricted, the angle θ facing the hot water surface 3 shown in Fig. 2 is close to a right angle, making it impossible to accurately detect the hot water surface position. Moreover, in the method shown in Figure 3, since the electrode is constantly immersed in the molten metal, the electrode is damaged and its fragments are mixed into the molten metal, causing foreign matter to be mixed into the casting material. There is a risk of contamination, and furthermore, with the method shown in Figure 4,
Since the bottom wall of the crucible 1 is inherently high temperature, the load cell 11
The problem was that it was difficult to apply it to the bottom wall.

[Means for solving problems]

Therefore, as a result of various studies to solve the above-mentioned problems, the present inventors mainly found that (1) since the amount of decrease in molten metal and the production amount of casting material are always equal, the amount of molten metal accumulated in the crucible If the specific gravity and cross-sectional area of the molten metal and casting material are both constant, the rate of descent of the molten metal level is proportional to the casting speed of the casting material.

(2) If the specific gravity and cross-sectional area of the molten metal and casting material are known in advance and the casting speed of the casting material is measured, the rate of descent of the molten metal level can be determined by calculation.

(3) Such calculations can be performed by the controller based on the detection signal of the casting speed detected by the sensor; (4) If the controller sends a drive signal corresponding to the melt level lowering speed to the pulse motor, (5) If the crucible is raised at a speed commensurate with the descending speed of the molten metal surface by the output of the pulse motor driven at this driving speed, the nozzle mold Ability to always maintain a constant hot water level position.

Focusing on this, we have completed a method for adjusting the level of the molten metal in the pressurized continuous casting method that allows for easy and accurate adjustment of the position of the molten metal level and eliminates the risk of foreign matter getting mixed in during casting.
Therefore, the present invention continuously produces a cast material by continuously pulling up molten metal accumulated in a crucible housed in a pressurized chamber through a nozzle mold inserted into the pressurized chamber from the outside. In the method of adjusting the molten metal level position in the pressurized continuous casting method,
A sensor detects the casting speed of the casting material pulled up through the nozzle mold, and then a controller electrically connected to the sensor calculates the lowering speed of the molten metal level from the casting speed, and A method for adjusting the hot water level position, characterized in that a drive signal corresponding to the surface lowering speed is sent to a pulse motor, and the crucible is raised at a rising speed corresponding to the hot water level lowering speed by driving the pulse motor. This is what we provide.

[Specific structure and operation of the invention]

(1) Detection of casting speed Generally speaking, the casting speed of the cast material may be detected by a sensor using any method, but the circumferential speed of the pinch roller that rolls the cast material usually matches the casting speed of the cast material. ,
It is convenient to detect the circumferential speed of the pinch roller with a sensor and send the detection signal to the controller, and a tachometer, for example, is used as this sensor.

(2) Calculation of hot water level lowering speed The controller calculates the hot water level lowering speed based on the detection signal of the circumferential speed of the pinch roller, and this calculation is performed using the following calculation formula.

The cross-sectional area and specific gravity of the cast material rolled by the pinch rolls are S1 and tel, respectively, and the cross-sectional area and specific gravity of the molten metal accumulated in the crucible, that is, the space inside the crucible, are S2 and ρ2, respectively. Assuming that the casting speed of the cast material, that is, the circumferential speed of the pinch roll, for example, is υ1, the cross-sectional area of the crucible is constant in the height direction.

If L is the amount of descent of the hot water level between time t1 and t2, that is, the distance by which the crucible should be raised, then the following equation (I) is established from the equation of continuity, and if this equation (I) is transformed, , the following formula (It) is obtained.

Therefore, 'lax r Sj , since 12.82 is known.

If the casting speed υ1 is detected by the sensor, time t1
The distance by which the crucible should be raised between 12 and 12 can be determined using the above equation (It).

A controller with a control function, for example, is used as a controller that performs such calculations and transmits a drive signal obtained by the calculations to the pulse motor.

(3) Before the crucible is raised, the pulsmoder that receives the drive signal from the left controller rotates, for example, its drive shaft at a speed corresponding to the drive signal, and this rotational torque is transmitted by various suitable transmission means. It is generally convenient to transmit the upward motion of the crucible through a transmission means such as a pinion or gear to a rotating shaft that moves the lifting legs of the crucible table supporting the crucible table in the vertical direction. For example, a DC servo motor is used as the pulse motor.

The controller may raise the crucible continuously by driving a pulse motor at a constant speed according to the calculated value, or may move the crucible a certain distance intermittently from time t1 to time t12. It is also possible to raise the temperature by the same amount.

[Examples and effects based on the examples]

Next, the present invention will be described by way of examples with reference to the drawings.

Embodiment 1 FIG. 1 is an overall configuration diagram of an apparatus used in carrying out this invention, and as shown in the figure, molten metal 2
The crucible 1 filled with the crucible 1 is placed on a crucible stand 13 provided in a pressurized chamber 12, indicated by a broken line. It is supported movably only in the vertical direction by the elevating legs 13a. A gear 13c is fixed to the lower end of the rotating shaft 13b, and this gear 13c meshes with a pinion 18a attached to a drive shaft 18b of the pulse motor 18.

On the other hand, the molten metal 2 in the crucible 1 is placed in a pressurized chamber 12.
The nozzle mold 6 is hermetically inserted into the pressurized chamber 12 from above to a predetermined depth.

That is, the nozzle mold 6 is immersed from its lower end surface to a predetermined position, and a water-cooled jacket 10 is attached above the nozzle mold 6 to cool and solidify the pulled-up molten metal.

Reference numeral 14 denotes a pinch roll that pulls up the cast material 15 cooled by the water-cooled jacket 10 and rolls it to a predetermined size.In order to detect the circumferential speed of the pinch roll 14, a pinch roll is placed opposite the peripheral edge of one of the rollers. A sensor 16 is attached to the sensor 16, and a detection signal obtained by the sensor 16 is sent to a controller 17 that is electrically connected to the sensor 16.

The controller 17 sends a drive signal based on the detection signal to the pulse motor 18 to rotate its drive shaft 18b at a predetermined rotational speed, and this rotational force is applied to the pinion 18a,
The rotating shaft 13b is rotated via the gear 13c, and the elevating leg 13a, which is threadedly engaged with the rotating shaft 13b, is raised at a speed equal to the circumferential speed of the pinch roll 14. The position of surface 3 is always maintained constant.

Therefore, in order to confirm the effects of the present invention when such a continuous casting apparatus is used, the following test was conducted.

Inner diameter: 200m x height: 285m in a pressurized chamber into which argon gas with a pressure of 0.30Kt/- is injected.
Crucible and inner diameter: Using a nozzle mold with 10 quakes, purity 9
Obtained by melting 40 kg of 9.99% copper. Temperature: 11
A pure copper rondo was produced from molten steel at 30±3°C by the method described below.

At this time, the specific gravity ψ1 and temperature of the steel rod = 1130℃
The specific gravity I2 of molten copper in is 8.94 and 7.94, respectively.
89. Therefore, from the above formula (II), the following formula (1) is obtained to calculate the distance by which the level of molten copper should be raised, and 1□ L-0,002831υ, dt... ...+1
) This formula ( ) is stored in the controller 17, and each time the L value calculated from the casting speed signal υ1 received from the sensor +)-16 reaches 1cIL,
The controller 17 is set in advance to transmit a drive signal to the pulse motor 18 to raise the casting speed by 1c11L, and under these conditions, the casting speed is increased to 10. Ocx/min
Casting of the steel rod was then started.

After starting casting and casting a calculated 30 Ky of copper rod, the operation of the casting device was stopped, and the distance of the crucible table 13 that had been raised during that time was measured.

The molten steel remaining in the crucible 1 was solidified and its weight was measured.

Based on the weight of the residual molten steel in the crucible 1 measured in this way, the distance by which the crucible table 13 should have been raised between the start and stop of operation of the casting equipment is calculated, and this value is calculated. When the error between this distance and the distance by which the crucible table 13 was actually raised was found to be ±11.

Example 2 A steel rod was produced under exactly the same conditions as in Example 1, except that the casting speed was 80α/min. A test was conducted to confirm the effectiveness of this invention.

As a result of the confirmation, the error in the molten steel level position was ±3 degrees.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to easily control the surface of molten metal in the pressurized continuous casting method.
and can be adjusted accurately.

Since the members, instruments, etc. necessary for the adjustment are never immersed in the molten metal, it is also possible to avoid the trouble of foreign matter getting mixed into the casting material.

[Brief explanation of drawings]

@Figure 1 is a configuration diagram for explaining an example of the method for adjusting the melt level of the present invention in the pressurized continuous casting method, and the second diagram is
4 through 4 are block diagrams showing a conventional hot water level adjustment method. In the diagram, 1...crucible, 2.
...molten metal. 3... Hot water surface, 4... ITV camera. 5...Monitor TV, 6...Nozzle mold. 7.8... Electrode, 9... Meter. 10...Water cooling jacket, 11...Load cell. 12... Pressurized chamber, 13... Crucible stand. 14...Pinch roll, 15...Casting material. 16... Sen f, 17... Controller. 18...Pulse motor.

Claims (3)

[Claims] (1) Molten metal accumulated in a crucible housed in a pressurized chamber is continuously pulled up through a nozzle mold inserted into the pressurized chamber from the outside, thereby continuously producing cast material. In a method for adjusting the level position in a pressurized continuous casting method, a sensor detects the casting speed of the casting material pulled up through the nozzle mold, and then a controller electrically connected to the sensor detects the casting speed. Therefore, the molten metal level descending speed of the molten metal is calculated from the casting speed, a drive signal corresponding to the molten metal level descending speed is sent to the pulse motor, and by driving the pulse motor, the molten metal level descending speed is adjusted to the molten metal level descending speed. The method for adjusting the hot water level position, characterized in that the crucible is raised at an appropriate rising speed. (2) The casting speed is detected by detecting the circumferential speed of a pinch roll that rolls the cast material pulled up through the nozzle and the mold, the hot water surface according to claim (1). How to adjust the position. (3) The lifting leg of the crucible table supporting the crucible is raised by driving the drive shaft of the pulse motor.
2) Method for adjusting the hot water level position described in section 2).