JPH07106437B2 - Twin drum continuous casting method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to twin-drum continuous casting, and more particularly to improvement of a method for pressing a side weir against an end surface of a cooling drum.

[0002]

2. Description of the Related Art In twin-drum continuous casting, as shown in FIG. 3, a pair of cooling drums 1 having rotating shafts 2 horizontally and parallel to each other and arranged at predetermined intervals are provided on both end surfaces 5 of these cooling drums 1. Growing on the surface of both cooling drums 1 rotating in the direction of arrow D while continuously pouring a molten metal into a continuous casting mold formed of a pair of pressed side dams 3 to form a pool 6 The pair of solidified shells thus formed are united to form a plate-shaped slab 8, and the slab 8 is sent downward by the rotation D of the cooling drum 1.

As shown in FIG. 4, on the back surface of each side weir 3, there are two places (4a, 4b) in the upper part and one place (4c) in the lower part.
Pressing force load devices 4 such as hydraulic cylinders at a total of 3 locations
a, 4b, 4c are mounted, and the front surface of the side dam 3 is pressed against the end surface of the cooling drum 1 by the pressing force applied to the back surface, and the cooling drum 1 moves along with the front surface of the side dam 3 along with the rotation D. Move.

From the viewpoint of maintenance cost, the wear caused by the frictional force on the sliding surface is preferentially generated on the side dam side rather than on the cooling drum side. Then, the side dam is continuously moved forward toward the end surface of the cooling drum during operation so as to offset the decrease of the side dam sliding surface due to wear and ensure the sealing action.

Here, it is important that the wear of the side dam progresses uniformly over the entire sliding surface. If the side weirs are unevenly worn, the seal cannot be uniformly maintained over the entire sliding surface, a defective seal is locally generated, and molten metal leaks, making it impossible to stably continue casting. In addition, uneven wear substantially shortens the life of the side dam. In particular, if there is a wear deviation between the upper and lower sides of the weir, it is likely to cause hot water leakage.
Its prevention is extremely important.

The amount of wear of each part of the side dam sliding surface is substantially determined by the frictional force acting on the sliding surface, and the frictional force is determined by the reaction force from the end surface of the cooling drum to the sliding surface. Japanese Patent Laid-Open No. 3-
Paying attention to this point, Japanese Patent No. 230848 (Japanese Patent Application No. 2-20481) measures the reaction force acting on the pressing force load device from the end surface of the cooling drum, and controls the forward displacement amount of the side weir based on this. Suggesting a way to do it.

However, the inventors of the present invention have conducted various experiments and found that even if the displacement amount control by reaction force is performed as in the above-mentioned prior art, a large deviation may occur in the amount of wear at the upper and lower portions of the side dam. However, uneven wear could not be sufficiently prevented.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a twin-drum continuous casting method and apparatus which effectively prevent uneven wear of side dams.

[0009]

In order to achieve the above object, a twin-drum continuous casting method according to the present invention comprises a pair of cooling drums whose rotation axes are horizontal and parallel to each other and which are arranged at predetermined intervals, and a rear surface. Forming a continuous casting mold with a pair of side dams whose front surface is pressed against the end surface of the cooling drum by a pressing force applied to the cooling drum. Applying pushing force 3
In the twin-drum continuous casting method in which the pressing force load members are simultaneously displaced in the direction of the pressing force at a constant speed, the following relationship: 0.8A ≦ (K _L / K _U ) ≦ 1.2A, where A = in F _Li / F _Ui where, K _L: stiffness of the bottom of the pressing force load member (kg / mm) K _U: the top of the pressing force load member 1 per stiffness (kg / m
m) (Two upper pressing force load members have the same rigidity) F _Li : Lower pressing force before starting casting (kg) F _Ui : Range of satisfying pressing force (kg) at each of two upper positions before starting casting Then, the pressing force of each portion and the rigidity of the pressing force load member are set.

Further, the twin-drum continuous casting apparatus for carrying out the method of the present invention comprises a pair of cooling drums whose rotating shafts are horizontal and parallel to each other and arranged at a predetermined interval, and a pressing force applied to the back surface. A continuous casting mold is constructed with a pair of side dams whose front surface is pressed against the end surface of the cooling drum,
Twin-drum continuous casting apparatus for simultaneously displacing three pressing force applying members for respectively applying the pressing force at a total of three positions, one lower part and two upper parts on the back surface of the side weir, at a constant speed in the direction of the pressing force. In the above, the rigidity of the pressing force load member of each of the above parts is expressed by the following relationship: 0.8A ≦ (K _L / K _U ) ≦ 1.2 A, where A = F _Li / F _Ui, where K _{L is the} lower pressing force. stiffness of the force load member (kg / mm) K _U: the top of the pressing force load member 1 per stiffness (kg / m
m) (Two upper pressing force load members have the same rigidity) F _Li : Lower pressing force before starting casting (kg) F _Ui : Range of satisfying pressing force (kg) at each of two upper positions before starting casting It is characterized by

[0011]

[Function] The side weir is pressed against the sliding surface by keeping the surface pressure of the sliding surface high until the initial familiarity is achieved, and then gradually decreasing the surface pressure to a surface pressure at which no water leakage occurs. It suppresses wear. As a result, the side blocking force (reaction force) decreases before and after casting.

First, in the present invention, the pressing force load members are simultaneously displaced at a constant speed at a total of three places, that is, two places on the upper side dam and one place on the lower side, especially in the above-mentioned initial high surface pressure period. This is to equalize the amount of wear.
Next, the reason for defining the rigidity ratio (K _L / K _U ) of the pressing load member of the present invention will be described.

In general, the proper side weir pressing force is not necessarily equal in the upper part (total of two places) and the lower part (one place), and is determined by the mechanical balance condition of the forces shown in FIG. In the figure, a cylinder (10
a, 10b) and a lower pressure generating cylinder (10c),
The upper pushing rods (11a, 1) that are substantially rigid
1b) and the lower push rod (11c), and the upper springs (12a, 12b) and the lower spring (12c) for absorbing the unevenness of the sliding surface, and the upper pushing force load device (4a, 4a, 4b) and a lower pushing force load device (4
c).

FIG. 1 schematically shows the force acting on each part, and the support for supporting the side weir upward is shown for the sake of convenience that the total support force is concentrated on the lower end of the side weir. The symbols in the figure are as follows. G: the side weirs centroid S: supporting point of the side weirs F _U: upper pushing force (kg) (1 point fraction equal pushing force F _U is loaded in two places.) F _L: lower pushing force (kg) F : frictional force between the cooling drum end face and the side weir sliding surface (kg) F = μ × ( 2F U + F L) (μ: friction coefficient between the cooling drum end face and the side weir sliding surface) L ₁ : center of gravity (common to the two pushing force) perpendicular distance (mm) between the G and the upper pushing force action line L _2: the center of gravity G and the lower pushing force perpendicular distance between the line of action (mm) L _3: the center of gravity G and the cooling drum Distance (mm) from end face Mechanical balance is as follows. Balance of force The force of the horizontal component is balanced by the action / reaction on the end surface of the cooling drum.

The forces of the vertical component are balanced by the action / reaction at the support points. Balance of Moments In FIG. 1, the moments about the center of gravity G due to the above-mentioned forces are expressed as follows. [Counterclockwise moment] ≡ [moment due to friction force] + [moment by the upper pushing force] _{= 2 (F U × L 1} ) + μ × (2F U + F L) × L 3 [clockwise moment] ≡ [lower pushing force Moment due to]] = _FL × L ₂ [Sum of moments around center of gravity G] = 0, that is, the following relationship is satisfied from the condition of [counterclockwise moment] = [rotational moment].

2 (F_U× L₁) + Μ × (2F_U+ F_L)
× L₃= F_L× L₂ From this, the [lower pushing force / upper pushing force] ratio, that is, F_L/ F_U
The ratio is F_L/ F_U= 2 (L₁+ Μ × L₃) / (L₂−μ ×
L₃) This relationship is always maintained during the pressing of the side weir.
It That is, the term of frictional force [μ × L₃]]
Lower pushing force F_LIs the upper pushing force F _U2 times (F_L= 2F_U)When
Must be F_L> 2F_UHas become.

Therefore, the upper pushing force (reaction force) before and after casting
Is not the same as the decrease amount of 2 points (2ΔF _U ) and the lower pressing force (reaction force) (1 position: ΔF _L ). ΔF _L > 2ΔF
_U ). Here, consider a case where the rigidity of the upper pressing force loading device (sum of spring constants of the springs 12a and 12b) and the rigidity of the lower pressing force loading device (spring constant of the spring 12c) are equal.

When the pushing force is changed under the above-described balanced condition, the pushing force change amounts (ΔF _L , ΔF _U ) of the upper and lower portions are different as described above, so that if the rigidity is the same, the upper and lower portions of the side weir are naturally inevitable. There is a difference in the amount of displacement. That is, when the rigidity of the spring is equal, the side dam displacement is proportional to the magnitude of the pushing force change amount due to the relationship of the side weir displacement amount = rod pushing amount + pushing force (reaction force) change amount / spring stiffness. The amount changes. The side weir displacement amount directly corresponds to the side weir wear amount, which results in uneven wear of the side weir.

In the present invention, the uneven wear is prevented by limiting the rigidity of the springs of the upper and lower pressing force applying devices to the following range with respect to the ratio (A) of the pressing force. 0.8A ≦ (K _L / K _U ) ≦ 1.2 A (1) where A = F _Li / F _Ui where K _L : rigidity of lower pressing force load member (kg / mm) K _U : Rigidity per one upper load member (kg / m
m) (Two upper pressing force load members have the same rigidity) F _Li : Lower pressing force before starting casting (kg) _FUi : Upper two pressing forces before starting casting (kg) The above relational expression The reason for defining (1) will be described below.

Since it is unlikely that the coefficient of friction will change significantly during casting, the following relationship holds. _{F Li / F Ui ≒ F Lf} / F Uf ≒ ΔF L / ΔF U = A F Li: lower before casting pushing force (kg) F _Lf: lower after casting pushing force (kg) F _Ui: before casting upper _{Pushing force} (one side) (kg) F _Uf : Upper _{pushing force} after casting (one side) (kg) Using this relationship, the reaction force is reduced by setting the rigidity of the pressing load device so as to satisfy the following relationship. The displacement amount of the side weir corresponding to can be made equal in the upper part and the lower part, and the uneven wear of the side weir can be significantly reduced.

K _L / K _U = A (2) K _L : rigidity of lower pressing device (rigidity of spring 12c) (kg
/ Mm) K _U:. Relationships rigidity of the upper pressing device stiffness (spring 12a and 12b on one side minute) (kg / mm) of the upper and lower stiffness ratio setting and the presence or absence of uneven wear can be explained as follows .

The reaction forces of the upper part and the lower part after a minute time t are P _U '= P _U -K _U × (ΔX _U -ΔY) (3) P _L ' = P _L -K _L × ( ΔX _L −ΔY) ... (4) Here, P _U ': upper reaction force after t time (kg) P _L': t lower reaction force time after (kg) P _U: upper reaction force of time 0 (time of operation start) (kg) P _L : Lower reaction force (kg) at time 0 (start of operation) ΔX _U : Side weir sliding surface wear amount at t time (upper part) (m
m) ΔX _L: side weir sliding surface wear amount at t time (bottom) (m
m) ΔY: Cylinder pushing amount at t time (mm) First, when the rigidity of the upper part and the lower part is the same as in the conventional case, if this is K, then K _U = K _L = K. The upper and lower ratio of the reaction force of
From (4), P _L '/ P _U ' = [P _L -K × (ΔX _L −ΔY)] / [P _U −K × (Δ
X _U −ΔY)] ≠ P _L / P _U.

The above relationship is expressed as ΔX after a minute time t._L≒ ΔX
_UIt also holds even if the condition of. That is, as wear progresses, the push
Since the vertical balance of force changes, uneven wear will result.
It On the other hand, according to the present invention, the lower ratio of rigidity is
If adjusted to the bottom-up ratio, K_L/ K_U= P_L/ P_U And from now on K_L= (P_L/ P_U) K_U Can be expressed as Using this, the reaction force lower ratio after t hours is P_L’/ P_L = [P_L-(P_L/ P_U) × K_U× (ΔX_L-ΔY)]
/ [P_U-K_U× (ΔX_U-ΔY)] = [P_L(1-K_U/ P_U× ΔX_L+ K_U/ P_U× Δ
Y)] / [P_U(1-K _U/ P_U× ΔX_U+ K_U/ P_U
× ΔY)] = P_L/ P_U(After minute time t: ΔX_L≒ ΔX_UIs established).

That is, even if wear progresses, uneven vertical wear does not occur because the vertical balance of the pressing force does not change. The present inventor has conducted various experiments based on a completely novel finding described above, the rigidity ratio in pushing force load device of the upper and lower (K _L /
It has been found that even if K _U ) does not necessarily satisfy the relational expression (2) exactly, but within the range of the relational expression (1) that is approximately satisfied, it is possible to remarkably reduce uneven wear of the side weir, and complete the present invention. It was

[0025]

EXAMPLE Plate-shaped slabs of SUS304 stainless steel were cast according to the present invention. The casting conditions were as follows. Casting condition A (≡F _Li / F _Ui ) = 2.8 Drum width: 800 mm, Drum diameter: 1200 mm Drum speed: 80 m / min, Slab thickness: 2.3 mm, Cast steel type: SUS304, Casting amount: 10 tons .

For comparison, the rigidity ratio (K _L /
Casting was performed including the case where K _U ) was out of the range of the present invention. After casting, the deviation in wear between the upper part and the lower part of the side dam sliding surface ceramic plate was measured to evaluate uneven wear. The results are shown in FIG. The rigidity ratio (K _L / K _U ) is F _Li / F
_Ui = 2.8 (= A), with K _L / K on both sides
_{When U} is in the range of 2.2 (0.8 A) to 3.4 (1.2 A), the wear deviation is substantially constant at 0.5 mm or less, but the rigidity ratio (K _L / K _U ). It can be seen that the wear deviation sharply increases outside the above range. In addition, when the rigidity ratio is less than the lower limit (0.8 A), the amount of wear in the lower portion is larger than that in the upper portion of the side weir, and when the rigidity ratio exceeds the upper limit (1.2 A), it is more than in the lower portion of the side weir. There is a large amount of wear on the top.

[0027]

As described above, according to the present invention,
In twin-drum continuous casting, uneven wear of side weirs and resulting leakage of molten metal can be effectively prevented, and stable casting can be performed.

[Brief description of drawings]

FIG. 1 is a layout view showing a relationship of forces applied to side dams in a twin-drum continuous casting apparatus according to the present invention.

FIG. 2 is a graph showing the relationship between the rigidity ratio and wear deviation of the upper and lower pushing force load devices according to the present invention.

FIG. 3 is a perspective view showing a main part of a twin-drum continuous casting device.

FIG. 4 is a front view showing details of a sliding portion between an end surface of the cooling drum and a side weir in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cooling drum 2 ... Rotating shaft 3 ... Side weirs 4a, 4b ... Upper pushing force load device 4c ... Lower pushing force load device 5 ... End surface of cooling drum 1 ... Hot water pool 8 ... Plate-shaped slab 10a, 10b ... Upper part Pushing force generating cylinder 10c ... Lower pushing force generating cylinders 11a, 11b ... Upper pushing rod 11c ... Lower pushing rod 12a, 12b ... Upper pushing force device spring 12c ... Lower pushing force device spring G ... Side weir the center of gravity S ... supporting point of the side weirs F _U ... upper pushing force (one place min. equal pushing force F _U is loaded in two places) F _L ... lower pushing force F ... cooling drum end face and the side weir sliding surface Frictional force between L ₁ ... Vertical distance between center of gravity G and upper pushing force acting line (common to two pushing forces) L ₂ ... Vertical distance between center of gravity G and lower pushing force acting line L ₃ ... Center of gravity G and cooling Distance from drum end face

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichi Wakiyama 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inori Hidenori Hattori 4-chome, Kannon Shinmachi, Nishi-ku, Hiroshima Prefecture 6-22 No. 22 Mitsubishi Heavy Industries Ltd. Hiroshima Works

Claims (2)

[Claims] 1. A pair of cooling drums whose rotation axes are horizontal and parallel to each other and are arranged at predetermined intervals, and a pair of side dams whose front surface is pressed against the end surface of the cooling drum by a pressing force applied to the back surface. In the continuous casting mold, three pressing force loading members for respectively applying the pressing force to the lower one place and the upper two places on the back surface of the side weir are provided at a constant speed in the direction of the pushing force. In the twin-drum continuous casting method of simultaneously displacing, the following relationship: 0.8A ≦ (K _L / K _U ) ≦ 1.2 A, where A = F _Li / F _Ui, where K _L : lower pushing force load member rigidity (kg / mm) K _U: the top of the pressing force load member 1 per stiffness (kg / m
m) (Two upper pressing force load members have the same rigidity) F _Li : Lower pressing force before starting casting (kg) F _Ui : Range of satisfying pressing force (kg) at each of two upper positions before starting casting Then, the twin drum continuous casting method is characterized in that the pushing force of each portion and the rigidity of the pushing force load member are set. 2. A pair of cooling drums whose rotation axes are horizontal and parallel to each other and are arranged at a predetermined interval, and a pair of side dams whose front surface is pressed against the end surface of the cooling drum by a pressing force applied to the back surface. In the continuous casting mold, three pressing force loading members for respectively applying the pressing force to the lower one place and the upper two places on the back surface of the side weir are provided at a constant speed in the direction of the pushing force. In a twin-drum continuous casting machine that simultaneously displaces, the rigidity of the pressing load member of each of the above parts is expressed by the following relationship: 0.8A ≦ (K _L / K _U ) ≦ 1.2 A, where A = F _Li / F _Ui K _L : Rigidity of the lower pushing force load member K _U : Rigidity per upper pushing force load member (Two upper pushing force load members have the same rigidity) F _Li : Lower portion before the start of casting pushing force F _Ui: that the top two places in before the start of casting Twin drum continuous casting apparatus characterized in that a range satisfying pushing force of les.