JPS6064754A - Method and device for casting continuously light-gage hoop - Google Patents

Abstract

PURPOSE:To obtain a light-gage hoop having excellent internal quality by press sticking the solidified shell formed on the surface of cooling rolls, detecting the loading load of the rolls arising therefrom and controlling the solidifying time within the spacing between the rolls so that the detected value attains a target value. CONSTITUTION:The rolling load P of a solidified slab 6 is detected by load detectors 9, 9' disposed on the rear surfaces of bearing boxed 8, 8' fixes by housings 12, 12' in the stage of forming a molten metal well between cooling rolls 3, 3' on the long side of a twin roll type continuous casting device and short side stationary plates 13, 13' consisting of refractories having small heat conductivity and press sticking the solidified shell 24 formed on the surface of the rolls 3, 3'. If the load P is large, the circumferential speed (v) of the rolls 3, 3' is increased and if the load P is small, the speed (v) is decreased to control the solidifying time in the spacing between the rolls and to control the press sticking length l to an intended value. The stable production of the light-gage hoop having excellent internal quality is thus made possible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a twin-roll continuous casting apparatus for directly producing thin strips from molten metal, and particularly for producing thin strips with excellent internal quality. The present invention relates to a suitable continuous casting apparatus.

[Background of the invention]

In recent years, there has been a demand for the development of high-speed casting machines for thin strip plates in the field of continuous casting. In particular, if high-quality wide steel strips with a thickness of 3 to 10 mm can be directly produced by continuous casting, revolutionary labor and energy savings can be achieved. However, conventionally, a slab with a thickness of 150 to 250 mm manufactured by continuous slab casting is reheated after removing surface defects, and then reduced in thickness by a rough hot rolling mill and a finishing rolling mill to produce the desired hot thin strip. was producing. Equipment costs, reheating energy, and rolling energy for this will become unnecessary if a thin strip continuous casting machine can be realized.

Well-known methods for obtaining thin strips include the Besosema method and the Hunter method9, some of which have been put to practical use in the field of non-ferrous metals. However, in steels with a high melting point and a slow solidification rate, leakage of molten metal or solidification smudges easily occur, so it was never put into practical use.

On the other hand, the solidification rate of molten steel is determined by the boundary heat transfer coefficient (
α) and the thermal conductivity (λ) of the molten steel itself, and is generally expressed as It will be done. In this formula, the value changes depending on the above-mentioned α and λ, and is approximately 20 to 25 in the mold. However, the α value actually changes depending on the surface condition of the cooling roll (roughness, type of coating, thickness, etc.), so even if the cooling time t is constant, the solidified thickness will not be constant. In some cases, the solidified slab is not necessarily crimped at the contact point between both cooling rolls, resulting in non-uniform internal quality11, which is a practical problem in terms of quality.

[Purpose of the invention]

The purpose of the present invention is to stably produce thin strips with excellent internal quality in a twin-roll casting machine by controlling the conditions for pressing the solidified shell at a constant level even when the solidification rate of molten steel changes. The object of the present invention is to provide a possible continuous casting method and apparatus.

[Summary of the invention]

The features of the present invention are based on the following findings.

That is, the crimping force at the crimping part is determined by the deformation resistance of the slab and the thickness of the slab formed on both rolls.

The thickness of the slab will be thicker if cooling is fast, and thin if cooling is slow.

Of course, if the thickness of the slab is large, the pressing force at the narrowest gap between the twin rolls will be large.

The deformation resistance of a slab is determined by the internal temperature of the slab, and is high when cooling progresses quickly and low when cooling progresses slowly. Therefore, depending on the magnitude of the pressing force, the internal state, ie, the thickness of the slab on the long side to be formed into a roll, can be indirectly detected. This method detects the reaction force exerted by the slab when it is crimped onto the cooling roll, or the rotational torque of the cooling roll.When this detected value is too large, it means that solidification is rapid, and conversely, when it is too small, it means that solidification is occurring. This means that the speed is slow, so if the rotational speed of the cooling roll is controlled depending on the magnitude of this detection level, the sum of the thicknesses of the slabs reaching the crimped part can be controlled at a constant level to the target level. It is possible. In this case, if a solidified shell is formed on the short side as well, the thickness of the solidified shell on the short side will not be compressed and deformed at the crimping part, and the crimping load will increase by this amount, making it difficult to accurately It is not possible to calculate the solidified shell thickness on the long side based on the compressive load.

Therefore, the characteristics of the present invention are that the short side is made of a refractory material with a solidified shell and has a low coefficient of heat conduction, and the long side of the blade is made of a cast iron material with a high thermal conductivity, such as a metal. The solidified shell formed on the long side, that is, the surface of the cooling roll is compressed, the resulting rolling load on the cooling roll is detected, and the solidification time in the cooling roll cabinet is controlled so that this amount is within an appropriate value. Above all, thin sheets of excellent internal quality are produced continuously.

The solidification time can be controlled by controlling the rotational speed of the rolls.

In this case, even if there is a slight variation in the creeping surface of the sump portions of both cooling rolls, there is a ripple effect in that the shadow caused by the increase or decrease in slab thickness is also eliminated at the same time. Similarly, for stable operation,
In some cases, it may not be desirable to drastically change the rotational speed of the cooling roll, so in that case, the molten metal is poured according to sprue detection to control the molten metal level, and the height of the molten sump is changed. It is also conceivable to prevent the rolling load from fluctuating as much as possible.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thin strip continuous casting apparatus which is an embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 are the configuration of a continuous casting apparatus showing one embodiment of the present invention, and FIG. 3 is a detailed view showing the state of crimping of the solidified shell in the above apparatus.

Although not shown, molten steel from a ladle is appropriately poured into the tongue pusher 1, and the immersion nozzle 2 directly connected to the lower part of the tongue pusher 1 is then passed through the cooling rolls 3 and 3' that constitute the twin rolls, and these two cooling rolls. The molten metal is poured into a boule located facing the molten metal and surrounded by a short side fixing plate 13, 13' made of a refractory material with low thermal conductivity. Although not shown, the cooling rolls 3 and 3' are configured to suppress the temperature rise of the rolls by forced internal cooling by circulating a cooling fluid. Cooling roll 3.
3' is rotatably supported at both ends by bearing boxes 7.7' and 8.8'.
8' is fixed by the housing 12.12'. Further, the cooling roll 3°3' is driven by a drive motor 22,
It is rotated in the direction of arrow a via the reducer 21 and gear distributor 20, respectively. The thin strip plate 6 that has been cooled and solidified through the cooling rolls 3 and 3' is pulled out by the pinch rolls 4 and 5 and transported to the next process.

Now, the cooling rolls 3, 3' are arranged at intervals to achieve the desired thickness (2 to 6 degrees), and the liner 1 is placed between the bearing boxes 7, 7' of the stationary cooling roll 3 and the housing 1212'.
The other cooling roll 3' has load detectors 9, 9' arranged on its back surface to detect the pressure reaction force of the solidified slab. The cylinders 14, 14' are arranged between the left and right bearing boxes 7, 8 and 7', 8', and have the role of removing looseness between the two bearing boxes.

Figure 3 shows the solidification state of the molten metal and shows the immersion nozzle 2.
The molten steel flow rate Q of the molten metal poured into the molten metal Pnir is controlled by a sliding valve or the like so that the molten metal level 25 becomes constant. The molten metal begins to solidify from point a, where the molten metal surface 25 comes into contact with the cooling roll 3' (or 3), and a cooling section continues until point b. In this section, the forming, solidifying, and crimping operations are completed, and the solidified shell 24 formed
grows according to the above-mentioned formula D=KV't, and at point C, the solidified shells on both sides formed on the cooling rolls 3 and 3' merge, and if the crimping is completed at C-b, the internal quality is good. A thin strip plate will be obtained, but as mentioned above, in reality,
Due to fluctuations in the melt level 25 and fluctuations in the solidification coefficient, the solidification thickness at point C is not necessarily constant, so the compressive force P (or torque T) of the crimping reservoir changes.

In other words, if the compressive force P (or torque T) is small, it indicates that the solidified thickness is small (if it is too large, rolling becomes impossible and sluggishness occurs), and conversely, if it is small, the solidified thickness is too small. In extreme cases, the center may be unsolidified and the hot water may leak after the cooling roll, or the plate may swell due to the static pressure of the molten steel after leaving the roll. Therefore, in order to perform proper crimping, it is sufficient to adjust the circumferential speed vf of the cooling roll so that the crimping force P (or torque) becomes a predetermined value. That is, when the pressing force P is small, the peripheral speed V of the cooling roll is increased, and when the pressing force P is small, the peripheral speed V is decreased. In this case, in the present invention, the short side 13
, 13' are made of materials with low thermal conductivity, so almost no solidified shell is generated on the short side, but even if it occurs, the thickness is extremely small, so the pressing force P is on the long side, In other words, the force is approximately equal to the force of pressing the solidified shell on the cooling roll side.

Next, a method of controlling the pressing force of the solidified slab will be explained using FIGS. 1 and 2.

That is, load detectors 9.9' are installed at both ends of the cooling roll 3.
Detects the compressive force P (not shown, but it is also possible to detect the rotational torque T from the current value of the cooling roll drive shaft or motor 22), adds it up with the adder 16, and sends it to the command unit 15 with the comparator 17. The driving speed of the cooling rolls 3 and 3' is adjusted so that this difference becomes zero.

Based on this difference, the arithmetic unit 18 outputs a command signal to give a command to the cooling roll drive motor 22 and the pinch roll drive motor 23 to synchronize the speeds of these drive motors 22 and 23. The pressure is controlled so that the pressure force P or torque T is always within a predetermined value.

In the same figure, the torque T is proportional to the product of the compression force P and the crimp length t, so T and P have a linear relationship, and the crimp load can be assumed using either amount. .

On the other hand, if the average deformation resistance of the material is 1o, the compressive force is the third
In the figure, P is proportional to 7, and if km is measured separately, the crimp length L can be calculated backwards from P or the actual torque measurement value.

As mentioned above, from the measured values of compression force P or torque T,
The crimp length t can be calculated backwards, so if P or T is constant, -
If the circumferential speed of the cooling roll is controlled so that the crimping length t
It is possible to control the value to the desired value.

Similarly, for the average deformation resistance of the material, a is 0.5 to 3 kg 7
At mouth 2, this varies depending on the material to be cast. 7 rolls
If it is 50 mm, the crimp length ti can be 100 m + n, so when casting a plate width B2 of 1000 mm, the compressive force P is:
If n = 2 kg / wn, then P =, t-Q,
-n=2X100X1.2X1000=240 tons.

Qp is a rolling force function and is approximately Q=1.2.

In addition, although FIGS. 1 and 2 show a technique in which the circumferential speed of the cooling roll is fully controlled as a means of controlling the compressive force P of the solidified shell, it is possible to control the height of the molten metal in the molten metal pool instead of this method. Even if controlled, the same effect can be achieved. That is, the sixth
A modification of the present invention described above in the drawings will be explained by showing only the menpush rotation. In FIG. 6, a partition is formed between the Kuunpush 1 and the immersion nozzle 2 passing through the nozzle 2 and between the twin cooling rolls 3, 3' and the short piece fixing plate 13, 13' (not shown). A flow control valve 30 is installed to adjust the amount of molten metal poured into the formed molten metal pool. This flow control valve 3
0 is a slide plate 31 having a flow port, and the slide plate 3
The servo valve 32 controls the size of the flow port of the slide plate 31 that communicates with the nozzle 2 by fully adjusting the sliding amount of the nozzle 2. As a command signal to the servo valve 32, a command signal f similar to that shown in FIG.
The adder 16 adds up the detected values of the compressive force P of the solidified shell (or the driving torque T of the cooling roll) detected at i', and the comparator 17 calculates the value from the command unit 15. Compare it with the target value and adjust the molten metal level 2 of the molten metal pool so that this difference becomes zero.
This is to adjust the height H' of 5. Then, based on this difference, the arithmetic unit 38 outputs a command signal, and the command signal is given to the servo valve 32 of the flow-side diagonal valve 30 to control the height of the hot water surface 25 and increase the pressure P or the pressure of the solidified shell. The torque T is adjusted so that it is always within a predetermined value.

Next, still another embodiment of the present invention will be described.

Fig. 1 shows the hooking method when the cooling rolls 3, 3' and the molten metal come into direct contact, but of course, as shown in Fig. 4, a bell) 40. The present invention can also be effectively utilized in injection compression casting. In the version shown in FIG. 4, the belt 40.41 is guided outward by guide rollers 42.43 and tied endlessly at the top.

Even if 40.41 is low A/@tight, 2
At the point where the two rolls are closest to each other, all of the molten metal solidified shells formed on the belts on both sides are crimped at this part, so a compressive load is generated at this crimped part.

However, if the belt is also driven in addition to the roll, the torque will be distributed to both sides of the roll and the belt, and the sum of both torques will be the load torque.

Further, the present invention can also be applied to a case where the belt is wound around one side of two rolls, and the other is composed only of rolls.

In any case, the present invention is effective when manufacturing a single sheet material by crimping slabs shaped on both sides through rolls or other material belts at the narrowest junction between two rolls. Become.

In addition, twin roll casting methods include the no-lid method, in which twin rolls are arranged horizontally and pouring is carried out horizontally, or the first method.
In the figure, there is a method of pouring metal upward from below the roll, but the present invention can be applied to any method of pouring metal in either direction.

Further, the twin rolls may have different roll diameters.

FIG. 5 shows yet another example to which the present invention can be applied. Fifth
What is shown in the figure is a pair of large and small cooling rolls #50, 51, in which molten metal is poured into the large roll 5o side through a nozzle 53, and a solidified shell 54 containing semi-solidified or unsolidified metal is formed. This is an example in which a thin plate 55 is manufactured by compressing and deforming this solidified shell between the rolls 51. Even in this case, the present invention can be effectively applied since the solidified state of the solidified shell 54 reaching this portion can be made uniform by measuring the compressive load at the compressed portion A.

In this case, it is better to synchronize the circumferential speed control of the rolls and the pouring control of the molten metal 53.

According to the embodiment of the present invention, the plate thickness is 1 to 6 mm, and the plate width is 500 to 50 mm.
1600mm thin strip plate has a casting speed of 10 to 100
Continuous and stable production was possible at m/=+.

That is, in the past, when cooling proceeded quickly using cooling rolls, the compression resistance at the crimped portion of the twin rolls became too strong, causing slippage between the slab and the rolls, or rotation of the rolls stopping.

In addition, if the cooling rate was slow, the inside of the crimped part would be in an unsolidified state, and the static pressure of the molten steel would swell the uncrimped part, and in the case of the extreme force field table, the slab would remelt and the molten metal would leak.

However, in the above-described embodiment of the present invention, since a solidified shell is desired to be formed on the short side and only the solidified shell formed on the roll coating surface corresponding to the long side is compressed, the compressive force of the crimping portion is small. This method measures all the crimp loads such as crimp torque, accurately predicts the total thickness of the solidified shell on the roll surface, and performs the work while controlling this so that it becomes the target value. These accidents did not occur, and stable continuous casting of thin strips became possible.

〔Effect of the invention〕

According to the present invention, in a twin-roll casting device, the conditions for compressing the solidified shell are controlled to be constant even when the solidification rate of molten steel changes, so that thin strips with excellent internal quality can be produced stably and continuously. It has the advantage that it can be manufactured in many ways.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a twin-roll type continuous thin strip casting apparatus according to an embodiment of the present invention, Fig. 2 is a plan view of Fig. 1, and Fig. 3 shows solidified shell formation and crimping in the roll section. An explanatory diagram showing the situation,
FIGS. 4 and 5 are schematic diagrams of a twin-roll casting machine according to another embodiment of the present invention, and FIG. 6 is a partial view of the tunnel and its surroundings showing another embodiment of the present invention. 1... tongue push, 2... immersion nozzle, 3.3'
...Cooling roll, 9,9'...Load detector, 13.
13'...Short piece fixing plate, 30...Flow rate control valve, 22
... Drive Mowaka K O Procedural amendment (method) % formula % Display of the case 1982 Patent Application No. 173837 Name of the invention Continuous casting method for thin strip plate and relation to the case concerning the person who corrects the device Patent applicant name A: f5101 Stock Company 44. jMade by Hitachi
Sakusho Osamu Hito No. 1 Kuni 6

Claims (1)

[Claims] 1. Molten metal is poured between a pair of rotating rolls or on the side of one of the rolls, and a solidified shell of the molten metal formed on the long side of the roll is formed on the two rolls. In a continuous casting method for thin strips in which thin strips are continuously manufactured by compressing them with rolls, the compression load acting on the rotating rolls is detected, and the solidification time of the roll cabinet is adjusted so that this value becomes the target value. A continuous casting method for a thin strip plate, characterized by controlling. 2. Scope of the Claims In claim 1, the continuous casting method of a thin strip plate is characterized in that the rotational torque of all the rolls under compression load or the reaction force of the compression rolls is detected (r). 3. Claims The method for continuous casting of a thin strip according to item 1, characterized in that the solidification time between the rolls is controlled by controlling the rotational speed of the rolls or controlling the height of the molten metal surface. 4. Melting. A nozzle for pouring metal, and a pair of rotating rolls capable of cooling the molten metal poured from the nozzle to form a solidified shell, and compressing the solidified shell to continuously produce a thin strip. In a continuous casting device for thin strip plates equipped with a metal plate, the short side is made of a material having a lower thermal conductivity than the roll so that a solidified shell can be formed on the roll, which is the long side in the cross section of the molten metal. A detection device is provided for detecting the compression load applied when the roll compresses the solidified shell, and a detection device for detecting the compression load applied when the roll compresses the solidified shell is provided, A continuous casting apparatus for a thin strip plate, characterized in that a control means is provided for controlling the solidification time of the solidified shell formed in the roll cabinet.5. A continuous casting device for a thin strip plate, characterized in that it is a torque detection device that detects rotational torque. 6. In claim 4, the detection and placement is a detection device that detects a compression roll reaction force of the roll. 7. A continuous casting apparatus for a thin strip plate, characterized in that it is a continuous casting apparatus for a thin strip plate according to claim 4, wherein the control means is a speed control device that controls the rotational speed of the roll. Continuous casting apparatus for band plates. 8. In claim 4, the control means:
1. A continuous casting device for thin strips, comprising a molten metal level control device for controlling the molten metal level height of the molten metal poured from the nozzle.