JPH0259158A - Method for changing width of mold - Google Patents

Abstract

PURPOSE:To prevent excess small or large taper and to remove danger of breakout by obtaining shifting velocity of a bottom part driving shaft so that a bottom part end position does not vary at the time of changing the inclination of a short side to drive a top part driving shaft and the bottom part driving shaft. CONSTITUTION:At first, the TOP driving shaft 7 is mainly shifted at the max. velocity for the period until a slab falls from meniscus 2 by descending and the BOTTOM driving shaft 10 is shifted by a little so that the variety of the BOTTOM end position 5 accompanied with the shift becomes zero. Successively, both of the TOP driving shaft 7 and the BOTTOM driving shaft 10 are shifted until the inclination from the meniscus 2 position to the BOTTOM end position 5 of the slab becomes the ideal inclination. The TOP and the BOTTOM driving shafts 7, 10 are shifted by equal velocities until a TOP end point 6 reaches to the finishing end point. Further, only the BOTTOM driving shaft 10 is shifted at the shifting velocity of the meniscus. Further, the TOP driving shaft 7 is fixed and only the BOTTOM driving shaft 10 is shifted at the shifting velocity of the meniscus.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention relates to a mold for continuous casting, and in particular, to a mold for changing the width of a slab during casting. (Side pieces of formwork) This relates to a mold width changing method of changing mutual widths.

(Prior art) Figure 4 is a schematic diagram of this type of mold.
The short piece 1 is paired with another short piece (not shown), and when the molten metal from the dollar turret is poured into the short piece 1 while cooling it with cooling water, the outer periphery of the molten metal is cooled and a shell is formed here. , when it passes through its lower end, it becomes the slab 4.

Here, the short piece 1 has a TOP drive shaft 7 on the outside separated downward by an appropriate dimension from the top (hereinafter also referred to as TOP) tip 6.
A BOTTOM drive shaft 10 is provided on the outside separated upwardly by a suitable dimension from the bottom (hereinafter also referred to as BOTTOM) tip 5, and these drive shafts are driven by a TOP drive motor 8 and a BOTTOM drive motor 11, respectively, to form a short piece. By changing the mutual spacing between the slabs 1, the width of the slab 4 can be changed.

In this case, a TOP position detector 9 is coupled to the TOP drive motor 8, a BOTTOM position detector 12 is coupled to the BOTTOM drive motor 11, and based on each detected value, the width of the short piece 1 and the inclination of the inner surface (hereinafter referred to as the amount of taper) are coupled. ) can be adjusted to the target value. Note that the taper amount is a value set depending on the condensation rate of the slab.

Therefore, the mold width can be changed at any time even during casting, thereby making it possible to meet the demand for a wide variety of slabs in small quantities.

FIG. 5 shows a specific procedure for widening the mold width by moving the short piece 1 with respect to the center 3 of the slab. That is, the TOP tip 6 is at LT and 807
When moving from a state where the 70M tip 5 is at LBo to a state where the TOP tip 6 is at LT4 and the 80770M tip 5 is at LB4, the short piece 1 is moved in the order of steps 1, 2, and 3.4. In this case, in step 1, the TOP tip 6
80770M When setting the position LB1 of the tip 5 and the moving speed V T t of the TOP drive shaft 7, BO
The moving speed V B t of the TTOM drive shaft 10 is determined according to the following equation.

Also, in other steps j (i -2, 3, 4), the position LT of the TOP tip 6, , [1
When the position LB of the 0TTOM tip 5 and the moving speed of the TOP drive shaft 7 are set to VBI, the BOTTOM drive shaft 10
The moving speed VBI of is determined by the following equation.

However, i-2, 3, 4.

In this case, the target value L of the TOP tip 6 when changing the mold width
T4 and the target value LB4 of the 80770M tip 5 are determined so as to satisfy the following relationship.

LT4-LB4x (110904x)...
(4) Where W: Width α of slab: Shrinkage rate: Taper amount.

Therefore, the width W of the slab, the shrinkage rate α when the molten metal solidifies
The target value LT4 and the target value LB4 of the 80770M tip 5 are obtained by calculation, and further, by setting the position of the TOP tip 6 for each step, the position of the 80770M tip 5, and the moving speed of the TOP drive shaft 7, +3
07 Since the moving speed of the TOM drive shaft 10 is calculated, the TOP drive motor 8 and BO are determined by referring to the TOP position detector 9 and BOTTOM position detector 2.
By controlling the speed of the TTOM drive motor 11, the mold width can be changed as shown in FIG.

(Problem to be Solved by the Invention) When the short piece 1 is moved by the above method, the position of the meniscus 2 and the position of the 80770M tip 5 as seen from the center of the mold change as shown in FIG. 6, respectively. In other words, if time t is plotted on the horizontal axis and distance W from the mold center 3 is plotted on the vertical axis, the position of the meniscus 2 changes according to the polygonal line 13, and the position of the 80770M tip 5 changes along the polygonal line 14.
changes according to

Here, the width between the polygonal lines 13 and 14 is constant in the range of steps 2 and 3, but in step 1. In the range of step 4, the middle portion is narrow. This means that the taper of the short piece 1 is not always constant during the width changing operation, and when the width is widened, there is an insufficient taper (a gap is created at the bottom), and conversely, when the width is narrowed, there is an excessive taper (a gap is created at the bottom).
Pressure is applied from above), which could lead to an accident in which the hot water shell ruptures, that is, a breakout.

Note that this is not limited to the mold width changing operation shown in FIG. 5, but is applicable to most molds that include the short piece inclination changing operation in the initial process of expanding the width of the slab and the final process of reducing the width. This was also a common problem with width changing methods.

The present invention was made to solve the above problems, and an object of the present invention is to provide a mold width changing method that can reliably prevent breakout of the slab due to movement of the short piece.

[Structure of the invention]

(Means for Solving the Problem) The present invention has a top drive shaft and a bottom drive shaft at positions separated by a predetermined dimension from the top and bottom tips of the short pieces constituting the mold, and In a mold width changing method, the top drive shaft and the bottom drive shaft are driven separately during the change, and the inclination change operation of the short piece is performed in an initial step of widening the width of the slab and a final step of reducing the width, respectively. , when changing the inclination of the short piece, find a moving speed of the bottom drive shaft such that the bottom tip position of the short piece does not change with respect to the moving speed of the top drive shaft, and adjust the top drive shaft and the top drive shaft respectively according to these moving speeds. It is characterized by driving the bottom drive shaft.

(Function) In this invention, when changing the inclination of the short piece, the moving speed of the top drive shaft and the moving speed of the bottom drive shaft are determined so that the bottom tip position does not change, and the top drive shaft and the bottom drive shaft are adjusted according to these moving speeds. Since the drive shafts are driven at the same time, it is possible to prevent the taper from becoming too small when widening the width or too much when narrowing the width, thereby eliminating the risk of breakout.

(Example) Fig. 1 is an explanatory diagram for explaining the present invention in detail, and in order to expand the mold width, a short piece 1 with the TOP tip 6 at the LT position and the 80770M tip 5 at the LBo position is used. Step 1. 2. 3.4. 5, and move the TOP tip 6 to the LT5 position, 80770M.
Make sure that the tip 5 is at the LB5 position.

In step 1, the TOP drive shaft 7 is mainly moved at maximum speed until the slab descends from the meniscus 2.
The 80770M drive shaft 10 is slightly moved so that the fluctuation of the 80770M tip 5 due to this movement becomes zero. In step 2, the part at meniscus 2 of the slab is 80
TOP until the ideal slope reaches 770M tip 5
Both drive shaft 7 and 80770M drive shaft 10 are moved. In step 3, the TOP drive shaft 7 and 80 are rotated until the TOP tip 6 reaches the final target LT5.
The 770M drive shaft 10 is moved by the same amount. Further, in step 4, only the 80770M drive shaft 10 is moved at the meniscus movement speed in step 3. Further, in step 5, the TOP drive shaft 7 is fixed, and only the 80770M drive shaft 10 is moved at a meniscus movement speed.

FIG. 2 is a diagram showing how the 80770M tip 5 and the meniscus 2 of the short piece 1 change due to the movement operations of steps 1 to 5. As in FIG. 6, the horizontal axis represents time t;
The distance @W from the slab center 3 is plotted on the vertical axis.

As is clear from this figure, when changing the mold width, the polygonal line 13 and 8
The width of the 0770M tip 5 with respect to the polygonal line 14 representing the temporal change is always constant, thereby eliminating the risk of breakout.

In addition, in the operation of step 1 above, the 80770M tip 5 is fixed and the T is mainly used until the slab comes down from the meniscus 2.
The OP drive shaft 7 is moved and the 80770M drive shaft 10 is slightly moved, and the reason for this will be explained below.

TOP drive shaft 7 and I30TTOM drive shaft 10 are TO
Since it is provided at a position separated from the P tip 6 and the 130TTOM tip 5, if the 130TTOM drive shaft 10 is fixed and only the TOP drive shaft 7 is driven, the 80770M
The tip 5 will bite inward. Therefore, it is necessary to drive the 80770M drive shaft 10 slightly in order to reduce this biting amount to zero.

FIG. 3 shows this relationship. First, when only the TOP drive shaft 7 is moved, the amount of movement 11 of the 80770M tip 5 toward the center of the mold can be calculated using the following equation.

However, ■Maximum moving speed t of T2 TOP drive shaft 7: Unit time r B: Straight distance α between 80770M drive shaft 10 and BOTTOM tip 5: Outer surface of BOTTOM tip 5 and short piece 1 as seen from 80770M drive shaft 10 Angle α between the TOP drive shaft 7 and the 80770M drive shaft 10 Angle L between the outer surface of the short piece 1 and the vertical plane as seen from the TOP drive shaft 7 and the 80770M drive shaft 10 L: Distance between the TOP drive shaft 7 and the 80770M drive shaft 10.

Next, when the TOP drive shaft 7 is driven at a speed V, 1:
Speed at which the BOTTOM tip 5 moves VBte BOTTO
When the M drive shaft 10 is moved and the TOP drive shaft 7 is fixed, the amount of movement 1° of the BOTTOM tip 5 in the mold center direction can be calculated using the following equation.

However, vB: Speed r T at which the BOTTOM tip 5 is fixed
: Straight line distance between TOP drive shaft 7 and BOTTOM tip 5 β Go BOTTOM tip 5 and short piece 1 seen from OP drive shaft 7
It is the corner with the outer surface of.

When the above equations (5) and (6) are equal, the BOTTOM tip 5 is fixed, so the following equation holds true.

As mentioned above, until the slab falls from meniscus 2,
The BO
The TTOM tip 5 can be fixed.

In addition, in the above embodiment, the first step when expanding the mold width was explained, but the final step of reducing the mold width is also done in the same way, and the bottom of the short piece 1 is It goes without saying that it is sufficient to find the moving speed of the bottom drive shaft 10 such that the tip position 5 does not change, and drive the top drive shaft 7 and the bottom drive shaft 10 in accordance with these moving speeds.

Furthermore, in the above embodiment, the steps shown in steps 1 to 5 are
Although the case where the mold width is expanded through so-called five steps has been described, the present invention is not limited to this. It has a top drive shaft and a bottom drive shaft, and when changing the width of the slab, the top drive shaft and the bottom drive shaft are driven separately, and the first step to widen the width of the slab and the final step to shorten the width. can be applied to most mold width changes that involve a short strip tilt change operation, respectively.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, when changing the inclination of the short piece, the moving speed of the top drive shaft and the moving speed of the bottom drive shaft are determined so that the bottom tip position does not change, and these moving speeds are determined. Since the top drive shaft and the bottom drive shaft are simultaneously driven according to the above, it is possible to prevent the taper from becoming too small when widening the width, or too much when narrowing the width, thereby eliminating the risk of breakout. can.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the invention in detail, and FIG.
The figure is a line diagram showing the relationship between the distance from the bottom tip of the short piece and the meniscus from the center of the slab and time, and FIG. Figure 4 is a schematic configuration diagram of a general mold, Figure 5 is an explanatory diagram showing the conventional mold width changing method, and Figure 6 is a short piece when this method is followed. FIG. 3 is a diagram showing the relationship between time and the distance from the bottom tip of the meniscus and the center of the slab. 1... Short piece, 2... Meniscus, 3... Center of slab, 4... Slab, 5... Bottom tip, 6... Top tip, 7... Top drive shaft, 8 ...Top drive motor, 9.
...Top position detector, 10...Bottom drive shaft, 11...
- Bottom drive motor, 12...bottom position detector.嶌30 Kan 1 diagram 2 diagrams - calculation 5 diagrams 6 diagrams t →

Claims (1)

[Claims] A top drive shaft and a bottom drive shaft are provided at positions separated by a predetermined distance from the top and bottom ends of the short pieces constituting the mold, respectively, and when the width of the slab is changed, the top drive shaft and the bottom drive shaft are separately operated. In the method for changing the width of the mold, the method includes an operation of changing the inclination of the short piece in an initial step of widening the width of the slab and a final step of reducing the width of the slab. A mold width characterized in that a moving speed of the bottom drive shaft such that the bottom tip position of the short piece does not change with respect to the moving speed is determined, and the top drive shaft and the bottom drive shaft are respectively driven according to these moving speeds. Modification method.