JP3082822B2 - Casting operation method of belt type continuous casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt-type continuous casting apparatus, and more particularly to a casting operation method in a belt-type continuous casting apparatus provided with an unsolidified rolling reduction device.

[0002]

2. Description of the Related Art FIG. 5 shows a belt-type continuous casting equipment provided with an unsolidified rolling reduction device and a method of operating the equipment which has been generally considered conventionally. In FIG. 5 (a ′), a belt-type continuous casting facility covers a metal belt 2 that circulates around a plurality of rolls 1 opposed to each other with a parallel gap, and covers the gap end of the belt 2. Circulating mold 3 with a cooling device composed of a short block connected body (not shown)
And a non-solidification drafting device 5 having a plurality of roll pairs 4 provided continuously below the belt circulation mold 3, and a guide roll 6 and a pinch roll (not shown) provided downstream of the guide roll 6. doing.

In addition, molten steel 8 is
A pouring nozzle 11 with a flow rate adjusting nozzle 10 connected to a tundish 9 for injecting water, a sensor 12 for detecting the level of the molten metal inside the belt circulation mold 3, and a molten metal according to the detected molten metal level. A control unit 13 for adjusting the opening degree of the flow rate adjusting nozzle 10 so as to keep the surface height at a predetermined position, a driving device 14 for circulating the belt and a driving device for a pinch roll (not shown) which are driven in association with each other at a constant speed; have.

[0004] solidifying the molten steel 8 was injected into the gap width (rolling before IhenAtsu) was kept at t ₁ belt circulating in the mold 3 is water cooled while being fed downward by circulation of the belt 2 sided portion The shell is formed and enters into the unsolidified drafting unit 5 while sufficiently unsolidified portions are left inside, and is pressed and formed into a slab 8a having a thickness t and guided by the guide roll 6 and the downstream pinch roll. And sent to a finishing mill or the like.

[0005]

In the above-described equipment, when the casting operation is completed, a conventional method shown in FIG.
As shown in (a ′) → (b ′), the flow control nozzle 10 is closed and pouring is stopped, and the casting 8a to be drawn out with a pinch roll is pushed down to the end and sent out, and FIG. 5 (a ′) →
As shown in (c '), a method has been considered in which the screw-down device 5 is opened to set the end of the slab 8a in an unpressed state, and then the pouring is stopped and then sent out.

According to the method shown in FIGS. 5 (a ') → (b'), the end of the slab 8a is lowered while being lowered away from the belt circulation mold 3, so that the inside of the slab 8a is not pressed. There is a disadvantage that the solidified molten steel 8 overflows from the top end of the slab 8a.

In the method of FIG. 5 (a ′) → (c ′), there is no overflow of the unsolidified molten steel 8 as described above.
Slab 8a rear end remains thick plate portion t ₁ ~t 'portion of the long non-pressure state ranging 4~5m shown in Figure 6, and poor product yield unsolidified rolling casting.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a casting method capable of terminating a casting operation without spilling over and minimizing a portion where rolling is not completed.

[0009]

In order to solve this problem, according to the present invention, in a belt type continuous casting equipment equipped with an unsolidified rolling reduction device, a predetermined time has elapsed after pouring is stopped at the end of casting operation. After that, the casting speed is reduced, and at the same time, the opening of the screw-down device is started, and after a predetermined time has elapsed after the opening of the screw-down device, the casting method is ended.

[0010]

According to the present invention, at the end of the casting operation, after a predetermined time has elapsed since the pouring was stopped, that is, in accordance with the time at which the surface of the molten metal in the belt circulation type mold descends to the predetermined position of the same mold, At the same time as the opening of the solidification rolling device is started, the casting speed is reduced to the time required for the required solidification time of the in-mold slab portion, and the casting operation is terminated after a lapse of a predetermined time required for the slab to pass through. As a result, the overflow of unsolidified hot water from the rear end of the slab is eliminated, and the length of the unrolled thick plate portion at the rear end of the slab is significantly shortened, so that the yield of products by the unsolidified rolling operation is increased.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the casting operation method according to the present invention will be described below in detail with reference to FIGS. FIG. 1 (a)
FIG. 2 is a side view showing an operation state of a belt-type continuous casting facility for performing the method of the present invention. In FIG. 1, the same elements as those of the apparatus shown in FIG. 5 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 1, reference numeral 7 denotes a pinch roll provided at a horizontal portion downstream of a plurality of pairs of guide rolls 6, and reference numeral 15 denotes a driving device for the pinch roll 7. Reference numeral 20 denotes a reduction control unit of the uncoagulating reduction device 5, and 21 receives a reduction amount signal and a reduction on or off signal from the reduction control unit 20, and receives a reduction on signal to control the driving device 14 for circulating the belt 2 and the pinch roll 7. The casting speed v ₁ before rolling down of the driving device 15 is set to a casting speed v = (t ₁ / t) × v ₁ according to the rolling down amount (t ₁ −t).
The speed v during the reduction is controlled by the reduction-off signal.
Is a casting speed control unit that controls the pre-rolling speed v ₁ to a deceleration speed or a low speed necessary for solidification of the unsolidified portion, or further controls the casting operation to be stopped for a certain time after the pouring is stopped.

The unsolidified drafting device 5 supports a drafting frame 5a equipped with a plurality of drafting roll pairs 4 so as to be able to swing oppositely by a fixed support shaft 5b on the same axis as the uppermost drafting roll pair. A universal nut 5c supported on the side plate 5a, and a reverse ball screw 5 screwed to the universal nut 5c
d, and a rotary drive motor 5e for the reverse ball screw 5d. The drive control unit 20 drives the drive motor 5e to move the left and right reduction frames 5a in opposition as indicated by an arrow 5f to reduce the required reduction amount. I'm trying to get. For the other parts, the conventional configuration shown in FIG. 5 may be used as it is.

1 (a), 1 (b) and 2 (c),
(D) shows a plurality of operation steps at the end of operation in the method of the present invention in order. FIG. 3 is an operation flow chart of the casting method of the present invention, which is performed using the apparatus shown in FIGS. Hereinafter, the procedure of the method of the present invention will be described with reference to FIGS.

In FIG. 1 and FIG. 3, when pouring is started at the same time as the operation of the belt-type continuous casting facility is started, the level detecting sensor 12 detects the level of the level in the belt-circulating mold 3 and the nozzle opening degree. Notify the control unit 13. The nozzle opening control unit 13 compares the detected level of the molten metal with the reference value, and when the reference value is not reached or exceeds the reference value, the flow control nozzle 10 is automatically opened and closed to control the flow rate. Keep the bath level at the reference level.

While the molten metal surface is kept at the reference height, the rolling-down operation of the unsolidified rolling-down device 5 is started by the rolling-down control unit 20, and at the same time, the casting speed v ₁ before rolling-down is reduced by the casting-speed control unit 21. The casting speed or v which is inversely proportional to (t ₁ -t)
= (T ₁ / t) × v ₁ . FIG. 1A shows this operation state, in which casting is continued while the fluctuation of the molten metal level accompanying the reduction of the unsolidified slab is kept to a minimum. This speed change control type unsolidified rolling casting operation is being separately proposed by the present inventors.

Next, when a predetermined amount of rolling operation is completed and the operation is terminated, in the present invention, pouring of the molten metal is stopped by the nozzle opening control unit 13, whereby the level of the molten metal in the mold 3 becomes a predetermined level (for example, 1/2 to 1 / from the lower end of the length of the mold 3
3 after the lapse of set time required for lowering to the height position, etc.), the low speed required casting speed non-solidified portion of the solidification rate v ₁ or less prior to reduction by the casting speed controller 21 Simultaneously with the deceleration, the screw-down control of the screw-down device 5 is started by the screw-down controller 12. FIG. 1B shows the state at this time.

The rear end portion of the slab descends at a reduced speed at a reduced speed, exits downward from the lower end of the mold 3, descends between the pressing roll pairs 4 in the middle of opening as shown in FIG. 2
As shown in (d), the rear end portion of the slab descends in a state where the pressing-down device 5 has completed opening. During the lowering of the slab in the process of FIG. 2, the slab is not reduced, and during the lowering, the unsolidified portion inside is completely solidified, so that no spillage from the rear end of the slab disappears, and a stable slab is formed. Can be pulled out.

Then, after the completion of opening of the screw-down device 5 is detected, after a set time necessary for the rear end portion of the slab to pass through the pinch roll 7 via the guide roll 6, the casting speed control unit 21 This completes the casting operation of the belt type continuous casting equipment.

At this time, by the above-described operation, the length of the unrolled thickness t _{1 at the} rear end portion of the slab becomes a short length corresponding to, for example, the height of two vertically aligned roll pairs. FIG. 4 shows the rear end of the slab produced by the method of the present invention. The length of the unrolled thickness t _{1 and} the length of the tapered portion t ′ in the middle of the reduction are:
Compared with the case of the conventional casting method shown in FIG. 6, the number is greatly reduced, and the yield of the cast product can be increased.

Therefore, according to the above-described method, the rapid fluctuation of the molten metal level in the belt circulating mold 3 caused by pressing down the slab 8a generated and sent out by the belt circulating mold 3 is eliminated, and Almost no occurrence occurs, and it is possible to obtain a slab of stable quality by controlling the nozzle pouring amount within an appropriate usage range, and at the same time, at the end of the casting operation, the length of the rear end portion of the unrolled portion to the unrolled portion. As a result, the yield of the product is improved to a minimum, and at the same time, the spilling of the slab during drawing is eliminated, and the stable drawing can be performed.

[0022]

In summary, the present invention relates to a belt-type continuous casting equipment equipped with an unsolidified rolling-down device, in which the casting speed is reduced after a predetermined time has elapsed after pouring is stopped at the end of the casting operation. By starting the opening of the screw-down device and ending the casting operation after a predetermined time has elapsed after the opening of the screw-down device, at the end of the casting operation, it is possible to eliminate the spillage of the slab at the time of drawing the slab and to achieve stable drawing. The present invention has an effect of enabling a casting operation and reducing the length of an unrolled portion left at the rear end of a slab to a minimum under an automatic control operation to improve product yield.

[Brief description of the drawings]

FIG. 1 is a side view showing a schematic configuration of a belt-type continuous casting facility for carrying out a method of the present invention, in which (a) is a side view showing a process in an operation state, and (b) is a process at the end of operation. Side view.

FIG. 2 shows two steps at the end of operation following FIG.
(C) shows a state in which the pressing roll pair is in the process of being opened, and (d) shows a state in which the pressing device has completed opening.

FIG. 3 is an operation flow chart of the casting method of the present invention performed by the equipment of FIG. 1 (a).

FIG. 4 is a side view of a rear end shape of a slab produced by the method of the present invention.

FIG. 5 is a side view of a belt-type continuous casting facility showing a conventional operation method, where (a ′) is an operation state, (b ′) is a state at the end of operation, and (c ′) is operation in another manner. The state at the time of termination is shown.

FIG. 6 is a side view of a rear end shape of a slab produced by a conventional operation method.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Touring roll 2 Metal belt 3 Belt circulation mold 4 Rolling roll 5 Unsolidified rolling device 6 Guide roll 7 Pinch roll 8 Molten steel 8a Cast slab 9 Tundish 10 Flow rate adjusting nozzle 11 Pouring nozzle 12 Metal level detection sensor 13 Nozzle opening degree control unit 14 Drive device for belt patrol 15 Drive device for pinch rolls 20 Reduction control unit 21 Casting speed control unit t ₁ Slab thickness before reduction t Slab thickness after reduction v ₁ Casting before reduction v Casting before reduction Single feed speed v Slab feed speed after reduction t 'Taper part where reduction is not completed

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-335759 (JP, A) JP-A-62-203652 (JP, A) JP-A-62-124056 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) B22D 11/06 340 B22D 11/10 B22D 11/128 350 B22D 11/20

Claims (1)

(57) [Claims] 1. In a belt-type continuous casting facility equipped with an unsolidified rolling-down device, at the end of a casting operation, after a predetermined time has elapsed after pouring is stopped, the casting speed is reduced and opening of the rolling-down device is started. And a casting operation method for a belt-type continuous casting facility, wherein the casting operation is terminated after a predetermined time has elapsed after the opening of the rolling-down device.