JPH0763811B2 - Clamping force setting method and clamping device for variable width mold for continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method of moving a short side of a mold during continuous casting to reduce the casting width while expanding the casting width. TECHNICAL FIELD The present invention relates to a method for setting a clamping force for a continuous casting mold that clamps a mold and a device therefor.

In particular, the present invention relates to a mold in which an appropriate mold clamping force can be set, a width of a cast piece can be changed in a short time, and a taper portion of the cast piece can be shortened as much as possible.

[Conventional technology]

As a clamping force setting method for a variable width casting mold for continuous casting, for example, in Japanese Patent Publication No. 59-29344, when moving the short side when changing the width, the clamping force is 1.1 to 2.5 times the molten steel bulging force and the width is changed. If not, 5 ~ 10 of molten steel bulging force
The clamping force was doubled and the setting was done in two steps.

On the other hand, as a mold clamping device, there is a mold clamping device described in Japanese Utility Model Publication No. 58-14033 shown in FIG. This makes it possible to adjust the hydraulic pressure supplied to the hydraulic cylinder 101, adjust the pressing force of the copper plate on the short side according to the operating changes during casting, and move the water box on the long side that is thought to occur as the pressing force is reduced. This is to be prevented by the mechanical stopper 102. Further, in Japanese Patent Publication No. 59-29344, as shown in FIG. 11, one long side 112 is a fastening rod 111 fixed to a water box.
A first end of which protrudes through the water box on the other long side 113, and has an elastic force larger than the pressure of the molten steel and smaller than the thermal expansion force of the copper plate on the short side 114 on the protruding portion.
The spring mechanism 115 and the second spring mechanism 116 having a larger elastic force than the first spring mechanism 115 are provided, and the fastening rod 111 is pressed against the tip of the fastening rod 111 in the axial direction of the long side. A second spring mechanism is provided by providing a device for relatively separating the copper plates from each other by a predetermined constant distance and compressing the first spring mechanism 115 by a predetermined dimension as the water box on the other long side 113 moves backward. It is disclosed that the elastic force of 116 acts as a clamping force for the copper plate on the short side 114. Among them, it is preferable that the force of the first spring mechanism 115 is 1.1 to 2.5 times the Balzinc force as described above, and the force of the second spring mechanism 116 is also 5 to 10 times.

[Problems to be Solved by the Invention]

The above-mentioned conventional techniques have the following problems to be solved.

In the case of the device described in Japanese Utility Model Publication No. 58-14033 in FIG. 10, the hydraulic pressure supplied to the hydraulic cylinder 101 is adjustable, and the pressing force of the short side plate can be adjusted according to the operation change during casting. Since the stopper 102 prevents the long side water box from moving during casting, the thermal expansion of the short side copper plate is restricted, and as a result, the contact surface pressure between the long side copper plate and the short side copper plate rises, causing the short side copper plate to deform. There was a problem that the mold life was shortened due to the occurrence of sliding flaws on the copper plate surface on the long side due to an increase in sliding resistance when the width was changed, and further, the driving force of the width changing device was large and installation was difficult. In particular, when trying to change the width at a high speed, the above problems have been a major obstacle.

Next, in the case of the device disclosed in Japanese Examined Patent Publication No. 59-29344 of FIG. 11, the elastic force of the first spring mechanism 115 is larger than the pressure of the molten steel acting on the long side, and the thermal expansion force of the copper plate on the short side. Since it is set smaller, no gap is created between the short-side copper plate and the short-side copper plate due to the backward movement of the long-side water box when the molten steel is poured into the mold, and the short-side copper plate is not heated. When expanded, the long side water box moves due to the expansion force, and the copper plates do not bite into each other. However, as disclosed in Japanese Patent Laid-Open No. 61-115656, the speed increase rate of the short side when changing the width is 50 mm / min ² , the speed difference between the upper and lower ends of the short side is 20 mm / min, and the moving speed of the short side reaches 100 mm / min. In the width changing operation, the contact resistance between the short-sided copper plate and the slab, that is, the pulling resistance is greatly increased due to the increase of the reaction force for pushing the slab when the width is changed. As a result, with the conventional clamping force determined by the molten steel bulging force standard on the long side, the pulling resistance becomes larger than the short side clamping force between the long side copper plates, that is, the clamping force.
The short side is dragged by the casting side, which causes improper synchronization with the mold vibration on the short side, causing an operational accident such as breakout.

[Means for Solving the Problems]

The clamping force setting method of the present invention, the short side of the mold is clamped by the long side of the mold, and when the casting width is expanded or reduced by moving the short side during continuous casting, the short side is the cylinder thrust F of the width changing device. _The clamping force F ₀ that is less than or equal to the limit clamping force F ₀₁ that can be moved with _cyL and greater than or equal to the limit clamping force F ₀₂ that prevents the short side from being dragged by the slab and moving in the casting direction. W, the bulging force F _BN , F _BW due to the static pressure of molten steel applied to the short side and the long side of the mold, the casting speed V _c , the moving speed of the short side V _m , and the friction coefficient between the slab and the long side of the short side of the mold. μ _s and the friction coefficient μ of the contact area between the short side and long side of the mold
It is a method of setting a clamping force for a variable width casting mold for continuous casting, which is characterized in that it is set by the parameter of _c . In this case, the limit clamping force F _{01 at} which the short side can be moved by the cylinder thrust force F _cyL of the width changing device and the limit clamping force F ₀₂ at which the short side is dragged by the slab and does not move in the casting direction are given below (1 ), (2) calculated, the limit clamping force F ₀₁ and F ₀₂
It is preferable to set the clamping force F _{0 according} to the following equation (3) so that the clamping force becomes between ₀ and.

F ₀₁ ≧ F ₀ ≧ F ₀₂ (3) Where, F _cyL : Cylinder thrust of width changing device W: Casting width F _BN : Bulging force due to static pressure of molten steel on short side F _BW : Molten steel on long side Bulging force due to static pressure V _c : Casting speed V _m : Moving speed of short side μ _s : Coefficient of friction between slab and long side of short mold μ _c : Friction coefficient of contact part between short side and long side of mold m, K ₁ , K ₂ , K ₃ , C ₁ : constant Further, the clamping device of the present invention, the clamping rod for clamping the mold short side with the mold long side is provided through the long side water box, Gate-shaped metal fittings capable of pressing the upper and lower sides of the rod are attached to both ends of the rod so as to face each other, and a hydraulic cylinder and a spring mechanism are connected in series to each leg of the gate-shaped metal fitting. The long side water box can be pressed by the hydraulic cylinder via the spring mechanism, the hydraulic cylinder is provided with a pressure adjusting mechanism, and the spring mechanism is set to the minimum spring force. A stopper for a clamping device of the width variable mold for continuous casting, characterized in that provided in the gantry hardware.

[Work]

INDUSTRIAL APPLICABILITY The present invention is a casting width W which is a variable requirement when moving a short side, bulging forces F _BN and F _BW by molten steel static pressure applied to the casting short side and the long side, a casting speed V _c, and a short side. Moving Speed
The clamping force F ₀ is set by adding all parameters of V _m , the friction coefficient μ _s between the slab and the long side of the mold, and the friction coefficient μ _c of the contact part between the short side and the long side of the mold. It is possible to change the optimum high-speed width during casting. Then, the above (1) and (2)
The formula (3) is calculated by a computer. As a result, it is possible to maintain an appropriate clamping force F ₀ corresponding to the ever-changing fluctuation requirements. As a result, automatic high-speed width change during casting becomes possible.

Furthermore, since the clamp device of the present invention is provided with the pressure adjusting mechanism in the hydraulic cylinder for clamping the short side of the mold with the long side of the mold, an appropriate clamping force F ₀ corresponding to the ever-changing fluctuation requirements. Can be automatically set by the pressure adjustment mechanism.
Further, since gate type metal fittings capable of pressing the upper and lower sides of the rod are attached to both ends of the fastening rod so that the long side water box can be pressed at two places, the height direction of the short side can be uniformly clamped.
Further, since the spring mechanism is provided with the stopper for setting the minimum spring force, the necessary minimum clamping force can be held only by the spring mechanism even if the hydraulic pressure of the hydraulic cylinder drops abnormally.

As described above, the present invention makes it possible to freely adjust the pressing force of the short-sided copper plate during casting and prevent the movement of the long-sided water box due to the decrease of the liquid pressure by the spring mechanism. It is possible to smoothly follow the thermal expansion and the thermal contraction when the casting speed is lowered, and the mold clamping force can always be optimally set according to changes in casting conditions, that is, casting width, casting speed, and width changing speed.

Hereinafter, the calculation basis of the equations (1), (2) and (3) will be described in detail.

FIG. 1 shows the force balance when the width of the mold is changed by pushing the shorter side of the mold during casting.

The required thrust of the cylinder is expressed by the following equation from the balance of forces.

F _cyL ≧ F _S ＋ F _BN ＋ FM _M (4) Where, F _cyL : Cylinder thrust of width changing device (kg) F _BN : Short side _bulging force (kg) F _M : Sliding of mold short side and long side Dynamic resistance (kg) F _S : Deformation resistance of solidification shell (kg) Where σ: Shell deformation stress (kg / mm ² ) S: Shell deformation cross-sectional area (mm ² ): Strain rate (1 / min) V _m : Short side moving speed (mm / min) W: Casting width (mm ) b: Deformation length of shell (mm) A, m: Constant (physical property value) Here, T: Casting thickness (mm) l ': short side slab support length _{(mm) F M = μ c} × (F 0 -F BW) ...... (7) Where, F ₀ : Clamping force (kg) F _BW : Long side bulging force (kg) μ _c : Friction coefficient of contact area between short side and long side of mold γ: Specific gravity of molten steel (kg / mm ³ ) l: Length Side-side slab support length (mm) Therefore, the mold clamping force for stably changing the width during casting using a cylinder with a predetermined thrust is obtained as follows.

From equation (4) and equation (7) Here, F ₀₁ : The limit clamping force (kg) at which the short side can be moved by the drive thrust force F _cyL of the width changing device. Also, the clamping force required to clamp the short side copper plate between the long side copper plates while changing the width. Is calculated as follows.

F _M ≧ μ _s × (F _S + F _BN ) …… (10) where μ _s : Friction coefficient between cast slab and copper plate From equations (7) and (10), Here, F ₀₂ : Limiting clamping force (kg) so that the short side is not pulled by the slab Furthermore, F ₀₁ and F ₀₂ are converted into equations (1) and (2). First, F ₀₁ is calculated from equations (8) and (9). Similarly, F ₀₂ is _calculated from equations (5) and (11) Becomes

Then, from the equation (3), the optimum mold clamping force F ₀ is obtained as the following range.

The basis for calculating the appropriate clamping force F ₀ has been described above, but the initial setting of the clamping force F ₀ at the start of width change will be described below.

For example, when the short side of the mold disclosed in Japanese Patent Laid-Open No. 61-115656 shown in FIG. 7 is moved to expand or reduce the casting width, the forward tilt period in which the movement of the short side is sequentially inclined toward the center of the mold and the mold reverse direction. A width changing method that is divided into a rearward tilt period that tilts toward the center side, and has a certain speed increase rate of the short side upper and lower end parts in the front and rear tilt period, while maintaining a constant difference between the upper and lower end move speeds. In the above, the initial velocity V ₀ at the start of width change is obtained as follows according to the casting width and casting speed. That is, assuming that the initial velocity at the start of width change is V ₀ and the casting width is W ₀ , from equations (5) and (9) Similarly, from equations (5) and (11) Therefore, rearranging V ₀ from Eqs. (15) and (16) Becomes

Here, since the casting width and casting speed are generally empirically determined in consideration of the productivity and operability of continuous casting equipment,
The optimum mold clamping force F ₀ when the width is changed is _calculated from the initial velocity V ₀ obtained from Eq. (17) as the following range.

[Embodiment] First, an embodiment of the mold clamping force setting method of the present invention will be described.

The embodiment of the present invention was carried out by the control flow shown in FIGS. Referring to the drawings below, the casting width W ₀ and the casting speed V _c at the start of width change are input to the width change control device from the process computer of the continuous casting facility. In response to this, the initial speed V ₀ is calculated by the equation (17) in the width change control device according to the logic shown in FIG. 3, and the optimum clamping force is calculated from this V ₀ (1) The limit clamping force from the cylinder thrust , F ₀₁ , (2) It is calculated from both sides of the limit clamping force, F ₀₂ , from the condition of synchronization with the mold vibration of the short side (the short side is not dragged from the slab).

As a result, the initial speed at which the above conditions (1) and (2) are satisfied
V ₀ and the clamping force F ₀ are obtained, the initial velocity V ₀ is transmitted to the width change command board, and the clamping force F ₀ is transmitted to the hydraulic control device. From this transmitted F _0, the supply pressure determined in the hydraulic control panel is supplied to the hydraulic cylinder of the mold clamping device via the pressure reducing valve, and the mold clamping force is adjusted to an optimum value. .

Specific initial velocity V ₀ and clamping force in the width change control device
The decision logic of F ₀ is as shown in FIG. That is, from the casting width W ₀ and the thickness B, and the casting speed V _c , the long side bulging force F _BW is _calculated from the formula (8), and the short side bulging force F _BN is _calculated from the formula (6).
From the equation, the deformation resistance of the solidified shell is obtained from the equation (5). From these calculated values, (1) the limit clamping force F ₀₁ from the cylinder thrust and (2) the limit clamping force F ₀₂ from the synchronization condition with the mold vibration on the short side were calculated, and the obtained F ₀₁ and
When F ₀₂ is compared and F ₀₁ = F ₀₂ is established, the initial speed V ₀ and the clamping force F ₀ at this time are determined as the set values when the width is changed. If F ₀₁ > F ₀₂ or F ₀₁ <F ₀₂ , the initial velocity V ₀ is corrected as shown in the figure and the calculation is repeated until F ₀₁ = F ₀₂ is satisfied. There is.

By the way, in the practical application of the equations (17) and (18), the constant term was obtained from the analysis results of many operation data at the test stage, and the following equation was used.

I.e. Also, (1) Clamping force from cylinder thrust: F ₀₁ (2) Limit clamping force from the condition of synchronization with mold vibration on the short side: F ₀₂ Where m = 0.40 K ₁ = 0.30 K ₂ = 1.60 K ₃ = 1.54 × 10 ⁶ K ₄ = 0.33 C ₁ = 1150 (kg) μ _c , μ _s = 0.30 Thus, FIG. 2 and FIG. According to the control flow shown in, when the initial setting when changing the width, changes in casting conditions,
That is, the mold clamping force F ₀ is optimally automatically set using a computer in accordance with the casting width, casting speed, width changing speed, and the like.

The automatic setting of the clamping force F ₀ is performed based on the mold clamping force control flow of FIG. However, the initial speed V ₀ of the width change control device is the short-side moving speed V _m .

FIG. 4 is a plan view showing a mold whose width can be changed. The mold is a long side copper plate 2, a long side water box 3 that supports it, and a long side copper plate 2.
A short side copper plate 4 that can be moved while changing the width, a short side back plate 5, a stepping cylinder 7 that moves the short side,
A mold clamping device 6 for strongly teaching the short-side copper plate between the long-side copper plates, and a base frame 1 on which these are collectively mounted. As shown in FIG. 5, the mold clamping device 6 includes a fastening rod 8 penetrating the opposite long side water boxes 3 and protruding at both ends, and a gate-shaped metal object capable of vertically decomposing a clamping force at one end of the protruding portion. 9, a gate type metal fitting 10 which is also provided at the other end and which can similarly distribute the clamping force up and down, a hydraulic cylinder 11 and a spring mechanism 12 arranged on this, and a hydraulic pressure to be supplied to the hydraulic cylinder 11. It consists of a hydraulic system that regulates.

Details of the spring mechanism are shown in FIG. This spring mechanism 12 is a spring 13 for setting the clamping force, and an inner cylinder that supports and guides the spring.
14, a retainer metal 15 for holding the spring, and a bolt 16 for integrating these. The hydraulic cylinder 11 is located at a position where it acts on the retainer hardware 15 of the portal metal fitting 10, and
It is fixed with bolt 17 to.

In these configurations, the mold clamping device functions as follows. First, with respect to the thermal expansion of the copper plate at the beginning of casting,
As shown in FIG. 6, the spring force of the spring mechanism is 1.2 times the long side bulging force without being pressed by the hydraulic cylinder. The spring force of this spring mechanism is limited by a stopper 19 provided on the gate-shaped hardware 10. Next, in the steady state of casting, the hydraulic cylinder is pressurized to bend the spring of the spring mechanism, and the clamping force is 2.5 times the long side bulging force. Further, when the width is changed, as described above, the pressure reducing valve 18 pressure is automatically set in the hydraulic control device based on F ₀ obtained by the logic flow shown in FIG. It is designed to adjust the supply pressure.

When the supply pressure to the hydraulic cylinder drops due to a failure of the pump of the hydraulic system, the width changing operation in progress is immediately stopped, but the spring force is 1.2 times the long side bulging force. The mechanism supports the copper plate on the short side without delay, and it is possible to continue normal operation.

Using the above invention, an operation was performed to reduce the width of a slab with a width of 1600 mm and 250 mm to 1200 mm during continuous casting. The casting speed at this time was 1.2 m / min, the initial velocity V ₀ of the cylinder at the top of the width changing device was found from equation (19), and was set to 15 mm / min, and the clamping force F ₀ was (20). From formula and (21) formula, 30,000kg
The supply pressure to the hydraulic cylinder is automatically adjusted according to this clamping force, and the maximum width change speed is 75 mm / m.
We were able to carry out the width change operation that reached in without any trouble. At this time, the length of the taper part of the slab shown in Fig. 7 can be reduced to about 1/2 or less compared to the conventional width changing speed of 20 mm / min, which greatly improves the slab yield. did.

〔The invention's effect〕

According to the present invention, (1) the taper length of the slab when changing the width is half that of the conventional
The product yield can be greatly improved. (2) During thermal expansion of the copper plates at the start of casting, the expansion force causes the long side water box to move smoothly and the copper plates do not bite into each other. Since the minimum spring force of the mechanism is made larger than the long side bulging force, there is no trouble such as breakout due to insufficient clamping force. (3) Initial speed when changing width automatically from casting size and casting speed command Also, since the clamp force is calculated and the supply pressure to the hydraulic cylinder can be adjusted via the hydraulic device, the clamp force is always optimally set and synchronized with the mold vibration on the short side due to the excess or deficiency of the clamp force. Stabilization of operation was achieved without problems such as defects. (4) The formula for calculating the required clamping force was theoretically obtained, and the constant term was obtained by collecting and analyzing a large number of operating data. It is possible to determine a clamping force that is sufficiently applicable to many operating factors that fluctuate from moment to moment, and (5) it is possible to automate the appropriate clamping force setting when changing the width, so the period required for stable operation is From 3 months
It can be shortened on the 10th day.

[Brief description of drawings]

FIG. 1 is a diagram showing a force balance when changing the width, FIGS. 2 and 3 are diagrams showing a mold clamping force control flow and a logic flow according to the present invention, and FIG. 4 is an overall plan view of the width changing mold. FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4 and shows the details of the mold clamping device, and FIG. 6 shows the mold clamping device during normal clamping, at the beginning of casting, and in an emergency (supply to the hydraulic cylinder). (When the pressure is reduced) showing the state of the spring mechanism and the hydraulic cylinder, FIG. 7 is a view showing the slab taper portion when the width is changed, and FIGS. 8 and 9 are explanatory views of the width changing method to which the present invention is applied. 10 and 11 are views showing a conventional mold clamping device. 1 ... Base frame, 2 ... Long side copper plate, 3 ... Long side water box, 4 ... Short side copper plate, 5 ... Short side back plate, 6 ...
… Mold clamping device, 7 …… Stepping cylinder, 8
...... Fastening rod, 9 …… Gate type hardware, 10 …… Gate type hardware, 11
...... Hydraulic cylinder, 12 ...... Spring mechanism, 13 ...... Spring, 14 ...
… Inner cylinder, 15 …… Hold metal, 16 …… Bolt, 17 …… Bolt, 18 …… Pressure reducing valve, 19 …… Stopper.

Claims (3)

[Claims] 1. When the short side of a mold is clamped by the long side of the mold and the short side is moved during continuous casting to increase or decrease the casting width, the short side can be moved by the cylinder thrust F _cyL of the width changing device. Clamping force F that is less than or equal to the limit clamping force F ₀₁ and greater than or equal to the limit clamping force F ₀₂ that prevents the short side from being dragged by the slab and moving in the casting direction.
₀ is the casting width W, the bulging force F _BN , F _BW due to the static pressure of molten steel applied to the short side and the long side of the mold, the casting speed V _c , the moving speed V _m of the short side, the length of the slab and the short side of the mold. The friction coefficient with the side μ _s ,
A clamping force setting method for a variable width continuous casting mold, which is set by a parameter of a friction coefficient μ _c of a contact portion between a short side and a long side of the mold. 2. A limit clamping force F _{01 for} which the short side is movable by the cylinder thrust force F _cyL of the width changing device, and a limit clamping force F ₀₂ for preventing the short side from being dragged by the slab and moving in the casting direction are shown below. Calculated by equations (1) and (2), the limit clamping force F ₀₁
The clamping force setting method for a continuous casting variable width mold according to claim 1, wherein the clamping force F ₀ is set by the following equation (3) so that the clamping force is between F ₀₂ and F ₀₂ . F ₀₁ ≧ F ₀ ≧ F ₀₂ (3) Where, F _cyL : Cylinder thrust of width changing device W: Casting width F _BN : Bulging force due to static pressure of molten steel on short side F _BW : Molten steel on long side Bulging force due to static pressure V _c : Casting speed V _m : Moving speed of short side μ _s : Coefficient of friction between slab and long side of short mold μ _c : Friction coefficient of contact part between short side and long side of mold m, K ₁ , K ₂ , K ₃ , C ₁ :: constant 3. A fastening rod for clamping the short side of the mold with the long side of the mold is provided through the long side water box, and a gate-shaped metal object capable of pressing the rod up and down is opposed to both ends of the fastening rod. And a hydraulic cylinder and a spring mechanism are arranged in series on each of the legs of the gate-shaped metal fitting,
The hydraulic cylinder enables the long side water box to be pressed through the spring mechanism, the hydraulic cylinder is provided with a pressure adjusting mechanism, and the spring mechanism is provided with a stopper for setting the minimum spring force on the gate-shaped metal object. A variable width mold clamping device for continuous casting.