JPH07106432B2 - Dummy sheet in twin roll type continuous casting - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to production of a thin plate slab by twin roll type continuous thin plate casting.

[0002]

2. Description of the Related Art By twin-roll type thin plate continuous casting, a thin metal slab having a plate thickness of 1 to 3 mm can be obtained. Therefore, it is possible to manufacture a thin metal plate that is difficult to roll. Further, when a thinner metal sheet is manufactured by rolling, the rolling process can be greatly simplified because the reduction amount is small.

FIG. 2 is an explanatory view of production of a cast piece using a twin roll type thin plate continuous casting machine. In FIG. 2 (A), the molten metal 5 includes twin rolls 1-1 and 1-2 that rotate in the direction of arrow 8 and a side weir 21.
It is poured into the pool 2 formed in. The molten metal is cooled by twin rolls to form solidified shells 3-1 and 3-2. The solidified shells 3-1 and 3-2 are united to form a slab 6, which is taken out from the minimum gap portion 4 of the twin rolls.

The solidified shells 3-1 and 3-2 are united in the vicinity of the minimum gap portion 4. FIG. 2B is an example in which the solidified shells 3-1 and 3-2 are united at 7 before reaching the minimum gap portion 4. When they are combined at 7, they are combined to a thickness of t ₂ mm, which is larger than t ₁ , but the solidified portion having a thickness of t ₂ mm is set to a twin roll minimum gap portion of t ₁ mm which is narrower than t ₂ mm. Regular work to pass through is not easy.

As described above, in the twin roll type thin plate continuous casting machine, since the solidified shells are united in the minimum gap portion 4,
Immediately before the minimum gap portion 4, the center of the plate thickness of the cast slab is in a molten state. Therefore, the microsegregation in the liquid state is scattered on the slab 6 immediately after coming out from the minimum gap portion 4, and the temperature is extremely high. Therefore, it is extremely vulnerable.

FIG. 3 shows an example of a traveling path for transporting the manufactured slab 6 to the winding machine 9. FIG. 3A shows an example in which the loop 10 is formed and then wound. At this time, the weight of the cast piece 6 of the loop 10 is applied to the cast piece immediately below the minimum gap portion 4. However, as described above, the slab directly below the minimum gap portion 4 is extremely fragile. Therefore, the slab directly below the minimum gap 4 cannot bear the weight of the loop 10, and the slab easily breaks immediately below the minimum gap 4.

FIG. 3B shows an example in which the descending slab is supported by the slide 11. At this time, the slab slides on the slide 11 and is then guided by the transport roll group 14. The weight of most of the slab is on the slide. Therefore, the cast piece is prevented from breaking immediately below the minimum gap portion 4. In FIG. 3 (B),
Although an example of the slide 11 having a smooth inclined surface is shown in the figure, it may be a slide that supports a cast piece from below using a number of horizontal rollers and guides the inclination.

In FIG. 3C, the pinch rolls 12 pressurize and support both sides of the cast slab. At this time, most of the weight of the slab is due to the pinch roll 12. Therefore, the slab is prevented from breaking immediately below the minimum gap portion 4.

Although FIG. 3 describes the traveling path of the slab, at the start of casting, a dummy sheet 13 is preliminarily provided along the traveling path of the slab between the minimum gap portion 4 and the winding roll 9 of FIG. Stretch over. One end of the dummy sheet 13 is engaged with the twin rolls 1-1 and 1-2, and the other end is fitted to the winding machine 9. When starting casting, after pouring the molten metal into the pool 2 of FIG. 2 (A), the twin rolls 1-1 and 1-2 are rotated in the directions of the arrows 8 and at the same time the winding machine 9 is rotated to form the dummy sheet. Wind up.
The molten metal is fused and solidified at the end of the dummy sheet in the pool 2 to form the tip of the slab. When the twin roll and the winding machine are rotated and the dummy sheet is wound by the winding machine 9, , The tip of the slab is guided by the dummy sheet, as shown in FIG.
It runs along the runway shown in (C) and reaches the winder 9.
It is wound after winding the dummy sheet.

[0010]

SUMMARY OF THE INVENTION The inventors of the present invention have shown in FIG.
A twin roll continuous casting machine of the types (B) and (C) was used to perform casting using a steel strip as a dummy sheet, but the vicinity of the tip of the slab sent after the dummy sheet. We learned that sharp folds and thin-walled areas occur. FIG. 4 is an explanatory view of the shape of a cast piece immediately after the start of casting. Sharp folds 17 occur at the joint between the dummy sheet 13 and the slab. Even if the dummy sheet 13 and the slab are joined to each other with a strength that does not break under normal tension, a sharp break 17
3 occurs, the joint portion reaches the transport roll group 14 in FIG. 3 or reaches the winding machine 9, and when the sharp fold 17 is corrected in shape and smoothed, the joint portion is broken. Reference numeral 18 is a bump-shaped portion having a large plate thickness. Subsequent to the nodule 18 the thin-walled area 16
Occurs. Since the thin area 16 has a small plate thickness, the cast piece is easily broken. The stationary portion 19 appears after the thin area 16. After the steady portion 19, the slab does not break, and the plate thickness of the slab does not significantly change.

As described above, in twin-roll thin plate continuous casting, sharp folds and thin-walled parts are generated, and in the ordinary method, they are easily broken in the process of reaching the winding machine. An object of the present invention is to provide a dummy sheet capable of preventing such breakage.

[0012]

Means for Solving the Problems JP-A-63-22484
No. 7 is a dummy sheet having a high melting point material typified by pure iron wire, mild steel wire, and stainless steel attached to its tip.
Although not described in JP-A-63-224847,
According to the knowledge of the present inventors, in the twin roll type continuous casting machine of the type shown in FIGS. 3 (B) and (C), it is not enough to prevent breakage only by attaching the above pure iron wire, mild steel wire and stainless steel. It is enough.

According to the present invention, at the end portion on the side where the slabs are connected,
It is a dummy sheet in which a linear, net-like, or thin plate-like reinforcing material selected from W, Ta, Mo, V, and Nb is joined so as to extend into the pool.

For example, Ni--Cu containing 50% by weight of Ni
The alloy thin plate, the Fe-Cu alloy thin plate containing 50 wt% Fe, and the Co-Cu alloy thin plate containing 30 wt% Co are
It is used in light electrical equipment, but it is difficult to manufacture thin plates by rolling.

According to the twin roll type thin plate continuous casting method, a thin plate can be directly manufactured from the molten metal. However, since these alloys for weak electric appliances are fragile particularly at high temperatures, they easily break when the sharp break 17 or the thin region 16 described in FIG. 4 occurs. As will be described later in detail, in twin roll type continuous casting,
It is not easy to completely prevent the sharp break 17 and the thin region 16 from occurring. Therefore, the present inventors have studied means for preventing the slab from breaking even when a sharp break 17 or a thin area 16 is generated.

The melting point of these alloys for light electrical equipment is 1350.
˜1450 ° C. Further, the temperature of the slab sent out from the twin rolls immediately after the start of casting shown in FIG.
It is 300 ° C. Table 1 shows examples of high temperature characteristics of W, Ta, Mo, V and Nb used as a reinforcing material in the present invention. In Table 1, pure iron, mild steel and stainless steel are comparative examples.

[0017]

[Table 1]

As shown in Table 1, the W, used in the present invention,
Since the reinforcing material of Ta, Mo, V, Nb has a high melting point, when it is used as a reinforcing material, it does not melt even if it is extended in the molten metal of the basin and has high strength at high temperature. Even with a wire, mesh, or plate having a thin wire diameter or a thin plate thickness, the slab sent out from the twin rolls immediately after casting is reinforced with a strong force. The diameter of the linear reinforcement is 0.1-1.
A 0 mm W wire, Ta wire, Mo wire, V wire, Nb wire, a net produced by using the above wire as a net reinforcing material, and a thickness of 0.1 to 1 as a plate reinforcing material. 0.0mm W, T
Thin plates of a, Mo, V and Nb can be used.

In the present invention, the reinforcing material is made to extend into the molten metal pool, but the length of the reinforcing material is preferably such that it projects above the molten metal bath surface of the molten metal pool 2 at the start of casting. In the present invention, at the end portion of the strip plate which is a dummy sheet, a linear shape, a net shape
The plate-shaped reinforcing material is joined, and this joining is performed, for example, by using a metal pad, sandwiching the reinforcing material between the band plate and the metal plate, and welding the metal plate and the metal band plate to each other, for example. It can be carried out.

[0020]

FIG. 1 is an explanatory view of the operation of the reinforcing member 20 of the present invention joined to the end of the dummy sheet 13. According to the present invention, in the slab sent out from the twin rolls immediately after casting, one end of the reinforcing material 20 is joined to the end of the strip 13, the sharp fold 17 and the thin region 16 are penetrated, and the other end is steady. Part 19
It is joined with the slab. Although the slab 6 may be cracked during sharp winding 17 or in the thin area 16 during the winding and winding process, in the dummy sheet of the present invention, even if the slab 6 is cracked, the reinforcing material 20 Since it penetrates, the slab is supported and connected by the reinforcing material, and the slab can be wound up on the winding machine without breaking.

As described above, pure iron, mild steel, and stainless steel are liable to be corroded by the molten metal when they are extended in the molten metal in the pool, and have low strength at high temperatures. Even when used as a sharp 17
When a crack occurs in the thin portion 16 or the thin portion 16, there is no strength to connect both ends of the crack, and the slab breaks when a crack occurs. For example, if a plate made of pure iron, mild steel, or stainless steel having a large plate thickness is used as the reinforcing material, the strength of the reinforcing material is increased, but as described later, the bump 18 becomes too large, and the thickness of the thin-walled area becomes thinner. Is not preferable.

The cause of the sharp break 17 in FIG. 4 is not necessarily known, but it is considered as follows.
FIG. 5 shows a twin roll type continuous casting operation immediately after the start of casting.
The twin rolls 1-1 and 1-2 rotate at a peripheral speed of V ₁ , and at the same time, the winding machine 9 also rotates at a peripheral speed synchronized with the twin rolls, for example, V ₁ . Therefore, at this time, the slab 6 is sent out from the twin rolls at a speed of V ₁ . The winder side 9'of the dummy sheet is V ₁
It is wound up at the speed of. However, since the dummy sheet 13 has a curl, a twist, and the like, there is a play shown in the corrugated form in FIG. 5 on the track. Twin roll side 11 'of the dummy sheets to this movement, although the speed of V ₁ after the play is lost by the winding, immediately after rotating the coiling machine at a rate of less V ₂ than V ₁ To do. Therefore, a compressive stress is generated between 4 and 11 'in FIG. 5, but since the joint between the slab and the dummy sheet is weak, this compressive stress causes a sharp bend 1.
7 is formed.

In FIG. 4, the cause of the thin region 16 is not always clear, but it is thought that the cause is as follows. FIG. 6A is an explanatory diagram of formation of the solidified shell 3-2 of FIG. When the level of the molten metal in the pool is a ', solidification of the solidification shell proceeds until the point a on the roll 1-2 reaches the minimum clearance 4, and the solidification shell in the minimum clearance 4 changes from 4 to 4a. It will be a total thickness. When the surface of the basin is b ', the solidified shell in the minimum gap portion 4 similarly has a thickness of 4 to 4b. As described above, the solidified shell becomes thicker when the molten metal surface is high and becomes thinner when the molten metal surface is lower. FIG. 6 (B) is immediately before the twin rolls are rotated. Before the twin roll is rotated, the molten metal is injected to a predetermined height in advance, but the solidification of the molten metal progresses while the molten metal reaches the predetermined height, and when the rotation is started, the minimum gap t A coalesced shell of t ₂ mm thicker than ₁ is formed. As shown in FIG. 6 (C), the combined solidified shells with a thickness of t ₂ mm are twin rolls 1-1, only during the passage.
1-2 is moved left and right so that the minimum gap is from t ₁ to t ₂ , but the movement of the twin rolls increases the volume of the pool and lowers the level of the molten metal. See also FIG.
In (C), the volume of the solidified substance taken out from the molten metal during the α seconds from time T ₀ to T ₀ + α is m ₁ , and T ₀ + α to T ₀
The volume of the solidified substance taken out from the molten metal during the α seconds reaching ₀ + 2α is m ₂ . That is, during α seconds from T ₀ + α to T ₀ + 2α, a solidified product of m ₂ larger than m ₁ is taken out from the basin. Therefore, the level of the molten metal is further lowered. As described above, immediately after the twin rolls are rotated, the level of the molten metal in the pool suddenly decreases. Becomes thin and forms a thin area.

The play of the dummy sheet in FIG. 5 and t ₂ in FIG.
Varies with work, so it is difficult to control with high precision. Therefore, in the twin-roll type thin plate continuous casting, sharp breaks and thin regions unexpectedly occur, but in the dummy sheet of the present invention, the reinforcing material prevents the slab from breaking.

[0025]

Example 1 Diameter is 0.3 or 0.5 mm and length is 2
The wire of the reinforcing material of various materials shown in Table 2 of 00 mm is attached to the end of the dummy sheet made of mild steel and the width of the dummy sheet is 10 mm.
For each 5 sheets, connect them and use these dummy sheets to
i-Cu alloy (Ni: 50%, Cu: 50%), Fe-Cu alloy
(Fe: 50%, Cu: 50%), Co-Cu alloy (Co: 5
A molten metal of 0% and Cu: 50% was cast. During casting, the molten metal bath surface of the pool 2 is about 175 from the minimum gap.
The height was mm.

In Table 2, No1 to No5 are examples of the present invention, and the material of the reinforcing material is W for No1, Ta for No2, Mo and No for No3.
4 is V and No5 is Nb. No6 and No7 are comparative examples,
As for the material of the reinforcing material, No6 is pure iron, No7 is stainless steel (S
US 304). No8 and No9 are comparative examples in which the diameter of the reinforcing material is 0.8 mm. No8 is pure iron and No9 is S.
US 304. On the other hand, No10 is a comparative example in which no reinforcing material is used.

[0027]

[Table 2]

* ◯: The connecting portion between the dummy sheet and the cast piece is not broken, ×: The connecting portion between the dummy sheet and the cast piece is broken, as shown in Table 2, when there is no reinforcing material or the reinforcing material is pure iron In the case of SUS304, the connecting portion between the dummy sheet and the cast piece is broken, but in No1 to No5 of the present invention, the connecting portion is not broken.

[0029]

[Embodiment 2] Plate thickness is 0.2 to 0.5 mm and length is 200 m.
The thin plates of the reinforcing materials of various materials shown in Table 3 of m are connected to one end of each dummy sheet, and these dummy sheets are used to form the same Ni-Cu alloy, Fe- A Cu alloy and a Co-Cu alloy melt were cast. Also in this case 2
The molten metal bath surface is approximately 175 mm high from the minimum gap.

In Table 3, No1 to No5 are examples of the present invention, and No.
6 to No. 7 are comparative examples.

[0031]

[Table 3]

* ◯: The connection between the dummy sheet and the cast piece did not break. X: The connection between the dummy sheet and the cast piece did not break. As shown in Table 3, in the case of pure iron SUS304, the connection between the dummy sheet and the cast piece was observed. Although the part is broken, No1 of the present invention
With No5, there is no breakage of the connecting part.

[0033]

When the dummy sheet of the present invention is used, the slab does not break during the process in which the slab immediately after the start of casting is conveyed to the winding machine.

[Brief description of drawings]

FIG. 1 is an explanatory view of the action of the dummy sheet of the present invention, FIG.
FIG. 3 is an explanatory view of production of a slab by a twin roll type thin plate continuous casting machine, FIG. 3 is an illustration of a traveling path for conveying the slab to a winding roll 9, and FIG. 4 is an explanation of a shape of the slab immediately after starting casting. Figure, Figure 5
FIG. 6 is a diagram illustrating breakage of a slab, and FIG. 6 is a diagram illustrating a thin region of the slab.

[Explanation of symbols]

1 (1-1, 1-2): Twin roll, 2: Hot water pool, 3
(3-1, 3-2): solidified shell, 4: minimum gap part,
5: Pouring molten metal flow, 6: Cast slab, 9: Winding machine, 10: Loop, 11: Slide, 12: Pinch roll, 1
3: Dummy sheet, 14: Conveying roll, 16: Thin area, 17: Sharp fold, 18: Bump-like part, 1
9: Steady part, 20: Reinforcement material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshito Nakao 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Co., Ltd. Central Research Division (56) References Japanese Patent Publication 4-20689 (JP, B2)

Claims (1)

[Claims] 1. At the end portion on the side where the slabs are connected, W, Ta,
Characterized by joining linear, net-like, and thin plate-like reinforcing materials selected from Mo, V, and Nb so as to extend into the pool.
Dummy sheet for twin roll type continuous casting.