JPH01215440A - Twin roll type continuous casting machine - Google Patents

Abstract

PURPOSE:To obtain a cast slab having a little plate thickness strain in the width direction and good shape by arranging inclining face at one end of mutually different side of each roll setting side dam between twin rolls and arranging corresponded inclining face at the side face of the side dam facing to the above inclining face. CONSTITUTION:A roll shift control device 13 outputs control signal to a roll shift devices 11a, 11b as matching to progress of deformation of roll surface, and the rolls 1a, 1b are shifted to roll shift line direction so that the inclining faces 15a, 15b invade in the mold to mutually reverse direction with the lapse of time. At the same time, an arithmetic unit 14 outputs driving signal to a driving device 10 to make opening degree of the rolls 1a, 1b largely. By this method, at the end part of the inclining face 15a, 15b side in each roll 1a, 1b, the inclining faces 15a, 15b are invaded to the position to come to crown small diameter part. On the other hand, at the end part of straight side without the inclining face 15a, 15b in each roll 1a, 1b, the crown small diameter part is formed. Therefore, intervals in the most approaching line of the rolls come to almost equal at the end parts and center part.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a twin-roll type continuous caster, and in particular, a twin-roll type continuous caster suitable for obtaining slabs with a good shape and less plate thickness in the width direction. Concerning continuous casting machines.

[Conventional technology]

The conventional twin roll continuous casting machine is shown in Fig. 9(a) and (b).
), the bearings 1 are placed parallel to each other at appropriate intervals.
Internal water-cooled twin rolls 101a and 101b rotatably supported by 00a and 100b, and a side dam 1 disposed close to the upper surface of the twin rolls to laterally close between the twin rolls.
The molten metal 10 is placed in the mold formed by 02a and 102b.
3 is injected, and while the twin rolls 101a and 101b are rotated in opposite directions, the molten metal pooled in the mold is cooled, and a strip slab 104 is obtained from between the rolls.

This twin-roll continuous casting machine has a roll 101a.

101b thermally expands due to heat input from the molten metal 103, and the roll surface is deformed into a roughly trapezoidal shape due to the temperature gradient at both ends of the roll, so that the thickness of the slab 104 is thinner at the center in the width direction and thicker at the ends. There was a problem of plate crown occurrence (5th
(see Figure and Figure 6).

Various plate crown reduction techniques have been proposed to address this problem.

One of them is JP-A-60-33857. In this method, a sleeve having a negative crown on the outer periphery and a negative crown on the inner periphery is attached to each roll, and this sleeve is expandable by cooling fluid pressure to control the roll crown.

Apart from this, as proposed in Japanese Patent Application Laid-Open No. 61-38745, there is also a water-cooled drum in which the shape of the outer peripheral surface can be controlled by pressurizing the cooling water inside the drum.

Furthermore, there is a method proposed in Japanese Patent Application Laid-open No. 60-27446, which has a sleeve with a cooling water flow path provided in a spiral shape, and has a piston sliding mechanism at both ends of the body that becomes narrower toward the center. A space is provided, an annular taper piston is slidably arranged in the space, and this is moved by hydraulic pressure, so that the roll crown can be changed as appropriate by the wedge action of the piston.

[Problem that the invention seeks to solve]

By the way, in a continuous casting machine, a large amount of thermal stress is applied to the sleeve of the roll due to a large amount of heat input, and a large amount of coolant flow rate is required to cool the sleeve. Under these conditions, various measures have been proposed as described above to reduce the deterioration of the plate crown due to roll thermal deformation, but these have the problems described below, and none of them have been put into practical use.

First, JP-A-60-33857 and JP-A-61-387
No. 45 has the following problems.

(1) Since cooling fluid pressure is used for crown control, the cooling characteristics change due to changes in fluid pressure, making stable control difficult.

(2) Originally, the flow rate of the coolant was large in order to cope with the large amount of heat input to the rolls, and the structure was designed to control this large flow rate of the coolant to obtain the fluid pressure change necessary for crown control. That's easy.

(3) A large amount of high-pressure fluid must be supplied, resulting in large energy consumption.

(4) At both ends of each roll in the axial direction, in order to prevent the cooling fluid from flowing out, there are 40
There is a part that secures a sealing mechanism and a flow path of about IIm, and this part becomes a crown uncontrollable zone.

As a solution to these problems, JP-A-60-2
No. 7446 is proposed. However, this prior art has the following problems.

(1) Since the cooling flow path is spiral, the flow path length is large. As a result, the driftwood resistance increases, making it impossible to increase the flow rate, and the temperature of the cooling fluid itself increases as it approaches the outlet side, increasing the temperature difference in the axial direction of the sleeve. This makes it difficult to reduce the deterioration of the plate crown.

(2) Since the position of the Taber piston is determined by hydraulic pressure,
The position of the Taper piston fluctuates greatly due to machining deviations on the fixed side sliding surface of the roll end and machining deviations on the taper piston itself, and the roll deformation is not symmetrical.

(3) When crown control is performed using the Taber piston, as shown in FIG. It deflects radially inward in an attempt to return to its original state, and the displacement of the roll surface at the roll end does not increase constantly toward the roll end surface. Therefore, the crown at the sheet end cannot be improved, but rather worsens. let

In view of the above-mentioned problems, the purpose of the present invention is to reliably control the crown of the roll ends, and to manufacture slabs with a small plate thickness in the entire width direction, including the plate ends. Our goal is to provide casting machines.

Means for Solving Problem C] The above object is to enable the twin rolls to be shifted in opposite directions to each other in the direction of the roll axis, and at one end of each roll on different sides, the outer diameter is changed toward the end of the roll. This is achieved by a twin-roll continuous casting machine characterized by providing an increasingly large sloped surface, placing a side dam between twin rolls, and providing a corresponding sloped surface on the side of the side dam that faces the sloped surface. .

[Effect]

When casting starts, the roll is heated and the roll surface is thermally deformed, and due to the temperature gradient at both ends of the roll, it tends to form a roughly trapezoidal crown (see Figures 5 and 6).The amount of this thermal deformation is It increases with time and reaches saturation at a certain point, so if each roll is shifted in the axial direction in opposite directions as the heat-deformed crown progresses, the above-mentioned inclination will be at the position where the crown diameter small portion of the above-mentioned one end of each roll should be. Since the small-diameter crown portion is located at the end of the opposite roll, the spacing in this part at the line closest to the roll is almost the same, and the thickness distortion at the end of the slab plate is reduced ( (see FIGS. 7 and 8), thereby preventing the plate crown from increasing in the entire width direction.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 7.

In FIG. 1, the twin roll continuous casting machine of the present invention includes twin rolls la and lb that are rotatably provided in parallel with each other while being appropriately spaced apart from each other, and the twin roll la.

A side dam 2a is arranged close to the upper surface of the rolls 1a and 1b between the rolls 1a and 1b, and closes the sides between the rolls 1a and ib.

Molten metal 3 is poured into the mold formed by 2b.

The rolls 1a, 1b are attached to shafts 4a, 4, as shown in FIG.
b, and sleeves 5a and 5b made of copper-based metal that are firmly shrink-fitted to the shafts 4a and 4b. A plurality of parallel annular grooves 6 are provided at the contact portions between the shafts 4a, 4b and the sleeves 5a, 5b as flow paths for cooling fluid, preferably cooling water.
a, 6b are provided to cool the sleeves 5a, 5b, and indirectly cool and solidify the molten metal 3. roll la
.

The end of 1b on the right side in the figure is connected to a drive device (not shown), whereby rolls la and lb are rotated in mutually opposite directions, and slab 7 is sent out from between both rolls 1a and 1b.

At one end of the different sides of the rolls la and lb, there is an inclined surface 15a having an angle α, the outer diameter of which increases toward the end of the roll.
15b is provided, and the side surfaces of the side dams 2a, 2b facing the inclined surfaces 15a, 15b are also provided with inclined surfaces 16a, 16b corresponding to the inclined surfaces.

The roll 1a is rotatably supported by fixed side bearing boxes 8a located on both sides thereof, and the roll 1b is rotatably supported by free bearing boxes 8b located on both sides thereof. A warm shirt and a key 9 are brought into contact with the free side bearing box 8b, respectively, and by driving the warm jacket 9 with a drive bag 210, the opening degrees of the rolls 1a and 1b can be adjusted.

Roll shift devices 11a, llb and shift amount detectors 12a, 12b are provided at the ends of the rolls la, lb on the non-drive side. The roll shift devices 11a and 11b respectively shift the rolls 1a and 1b in opposite directions in the direction of the roll axis so that the inclined surfaces 15a and 15b enter the mold, and the shift amount detectors 12a and 12b respectively shift the rolls 1a and 1b in opposite directions. Detect shift amount.

Shift amount detection signal S1 of shift amount detectors 12a and 12b
．． 32 is sent to the shift control device 13.

The shift control device 13 is preset with a relationship between the casting time t and the roll shift amount S as shown in FIG.
Detection signals S1 and S2 of shift amount detectors 12a and 12b
Checks whether or not is the set value S, and if not, outputs the output signal of the difference to the roll shift devices 11a, llb, and the detection signal 31, 32, that is, the shift amount of the rolls 1a, 1b, becomes the set value. control to match S.

As a result, synchronization control is performed to equalize the shift amounts of the shift devices 11a and flb.

On the other hand, a calculation device 14 is provided for the drive device 10 of the worm jack 9. The arithmetic unit 14 includes a fourth
The relationship between the thermal expansion amount δ0 of the rolls la and 1-b and the casting time as shown in the figure is input in advance, and using this relationship, the necessary roll opening adjustment amount 53 = 2δ0 is calculated, and the drive device Output to 10. In this way, the twin rolls 1a,
A roll opening degree adjusting device is configured to adjust the roll opening degree in accordance with the amount of radial thermal expansion of 1b.

Next, the operation of the twin roll continuous casting machine configured as described above will be explained.

When starting casting, first set the side dam 2 according to the width of the slab.
a, 2b are spaced and positioned 0 then,
The starting point Aa of the inner surface of the side dams 2a, 2b and the inclined surfaces 15a, 15b of the rolls la, lb.

The axial positions of rolls la and lb are determined so that Ab coincides with each other, and then the rolls la and lb and the side dam 2a are
, 2b is set to be 0.1- or less. In this state, the opening at the line closest to the roll is rectangular, and immediately after the start of casting, the slab 7 has no crown.
is obtained.

When the casting time elapses, the rolls 1a and 1b are heated and the roll surfaces tend to be thermally deformed into approximately trapezoidal crowns. The amount of this thermal deformation increases with casting time and becomes saturated at a certain point. As this deformation progresses, the roll shift control device 13 outputs a control signal to the roll shift devices 11a and llb based on the relationship shown in FIG. 3, and sequentially moves the rolls la and lb in opposite directions. Slanted surface 15a,
15b is shifted in the roll axis direction so as to enter the mold. At the same time, the calculation device 14 outputs a drive signal to the drive device 10 based on the relationship shown in FIG.
Increase the opening degree of 1b. This allows each roll la, l
At the end of the inclined surfaces 15a, 15b of the rolls 15a, 15b, the inclined surfaces 15a, 15b enter the position where the crown diameter is small, and on the other hand, the inclined surfaces 15a, 1 of the rolls la, lb
A small diameter crown portion is formed at the end portion on the straight side without 5b. Therefore, the spacing at the line closest to the rolls is approximately the same at the ends and the center, and the crown at the end of the plate is reduced.

This will be explained in more detail below with reference to FIGS. 5 to 8. Figure 5 shows the thermal deformation of conventional rolls 101a and 101b (see Figure 9) without inclined surfaces 15a and 15b. As time passes, the side dams 102a, 1 are thermally deformed into a roughly trapezoidal shape as shown by the broken line, and the side dams 102a, 1
A radius difference of δ occurs between the width direction end portion defined by 02b and the center portion. This results in an edge-up of 2δ in terms of the plate thickness of the slab, and the cross-sectional shape of the obtained slab becomes a round shape as shown in FIG.

On the other hand, in this embodiment, since the inclined surfaces 15a and 15b are provided at one end of the rolls la and lb, the shape of the thermal deformation is as shown by the broken line in FIG.
The end on the straight side without b has a roughly trapezoidal shape as before, but the end on the non-straight side has an inclined surface 1
5a and 15b, the inclined surfaces 15a and 15b become inclined surfaces having an inclination angle smaller than the inclination angle α of the inclined surfaces 15a and 15b in a direction opposite to the straight side.

Therefore, by shifting the roll 1a to the left by the dimension S1, at the straight end where there is no inclined surface 15a,
A radius difference of δ occurs as in the conventional one shown in FIG. The same amount of radius difference δ can be produced in the direction.

On the contrary, the opposing roll 1b is shifted to the right by the same distance S2, so that a radius difference δ occurs at the end in an opposite relationship to the roll 1a. That is, at the end of the roll 1b facing the straight end of the roll 1a, a radius difference δ due to the inclined surface 15b occurs in the opposite direction to the radius difference δ at the straight end, and the opposite straight end of the roll 1a At the end of the roll 1b opposite to the side end, a radius difference δ occurs in a direction opposite to the radius difference δ at the opposite end. As a result, the gap at the line closest to the rolls becomes the same across the entire width direction between the ends and the center of the rolls, and the resulting slab has a cross-sectional shape as shown in FIG. Since this cross-sectional shape has a substantially constant plate thickness, it can be easily flattened by rolling performed after casting, and an increase in the plate end crown can be prevented.

As can be seen from the above description, the inclination angle α of the inclined surfaces 15a and 15b is selected so that the inclination when a thermal steady state is reached is parallel to the inclination of the straight side end.

Furthermore, as the thermal deformation of the rolls la and lb progresses, the distance between the rolls la and lb in the area where the side dams 2a and 2b are inserted becomes narrower due to roll thermal expansion, so the roll opening degree is increased by 2δ0 as described above. and roll la, l
b and side dam 2a.

Maintain appropriate relationships with 2b. This also applies to roll 1
It also means keeping the distance between the outer surfaces of a and 1b constant,
Thereby, the thickness of the slab 7 can always be kept constant. Furthermore, since the relationship δ0>δ holds between the expansion amount δO and the radius difference δ, it is sufficient to increase the roll opening degree by 2δO, and the diameter change due to roll shift is taken into account when adjusting the roll opening degree. There's no need.

The above operations are continued until the temperatures of rolls la and lb are saturated. This takes approximately 1 to 2 minutes, and thereafter, casting is performed while maintaining the same roll shift and roll opening.

In this way, in this example, the increase in plate crown due to roll thermal deformation during casting, especially the increase in crown at the ends in the width direction of the plate, can be canceled from the beginning of casting until thermal stability is reached. It is possible to efficiently produce slabs with a good shape and less distortion in plate thickness.

Further, in this embodiment, the outer circumferential sleeves 5 of the rolls la and lb are
a and 5b are made of copper-based metal with good thermal conductivity. Copper-based metals have a higher coefficient of linear expansion than iron-based metals, but because of their good thermal conductivity, the amount of temperature rise is reduced by more than the linear expansion coefficient, and as a result, the amount of thermal expansion is reduced. Also, the sleeves 5a, 5
There are parts of the inner surface of the end portion of b that cannot be directly cooled by the cooling grooves 6a and 6b, but by using copper-based metal, heat transfer from the center part in the width direction to the end part is promoted, and the temperature in the width direction is reduced. The distribution becomes more even. As a result, the temperature gradient at the end of the roll is reduced, and the radius difference δ shown in FIG. 7 can also be made smaller than the conventional radius difference δ shown in FIG. 5, allowing better control of the plate crown. It becomes possible.

Note that the above embodiment can be modified in various ways within the spirit of the present invention.For example, in the above embodiment, a preset signal based on the relationship shown in FIG. 4 was used to adjust the roll opening degree. It is clear that well-known techniques such as (1) measuring the amount of thermal expansion of the roll, (2) measuring the thickness of the fi piece, etc. may be used. Of course, a conventional variable crown roll may also be used.

[Effects of the Invention] As is clear from the above, according to the present invention, it is possible to reduce crowns at the ends in the width direction of the plate, and to efficiently produce slabs with good shape and less distortion in plate thickness throughout the width direction. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a twin roll continuous casting machine according to an embodiment of the present invention, FIG. 2 is a sectional view of the twin roll continuous casting machine, and FIG. 3 is a plan view of the twin roll continuous casting machine. 4 is a diagram showing the relationship between the casting time t set in the shift control device and the roll shift amount S, and FIG. 4 shows the relationship between the casting time t and the roll expansion amount δ set in the calculation device of the continuous casting machine. FIG. 5 is a schematic diagram showing the roll thermal deformation state in a conventional twin-roll continuous casting machine, and FIG. 6 is a schematic diagram showing the roll thermal deformation state shown in FIG. FIG. 7 is a diagram showing the cross-sectional shape of the piece, and FIG. 7 is a schematic diagram showing the roll thermal deformation state in the twin-roll continuous casting machine of the present invention.
Fig. 8 is a diagram showing the cross-sectional shape of the slab obtained in the thermally deformed state shown in Fig. 7, and Fig. 9 (a> and Fig. 9 (b) respectively show the conventional twin-roll continuous casting method. They are a plan view and a side view of the machine, and Fig. 10 is a cross-sectional view of a main part of a roll showing roll deformation during roll crown control in a conventional twin-roll continuous casting machine. Rolls 2a, 2b... Side dam 3... Molten metal 5a, 5b... Sleeve 6a; 6b... Cooling channel 7... Slab 9... Worm jack 10... Drive device 11a, llb.
... Roll shift device 13 ... Shift control device 14 ... Arithmetic device (roll opening adjustment device) 15a, 1
5b-...Slope 16a, 16b...Slope Applicant Hitachi, Ltd.

Claims (3)

[Claims] (1) Molten metal is poured into a mold formed by twin rolls that are freely rotatable in parallel with each other and spaced apart from each other, and a side dam that is placed close to the upper surface of the twin rolls and closes the sides between the twin rolls. In a twin-roll continuous casting machine that injects molten metal, cools the molten metal, and then casts a slab from between the rolls, the twin rolls can be shifted in opposite directions to each other in the roll axis direction, and one end of each roll on different sides. The roll has a sloped surface whose outer diameter increases toward the end of the roll, the side dam is placed between the twin rolls, and a corresponding sloped surface is also provided on the side surface of the side dam that faces the sloped surface. Twin roll continuous casting machine. (2) A twin-roll continuous casting machine according to claim 1, characterized in that a roll opening adjustment device is provided for adjusting the roll opening in accordance with the amount of radial thermal expansion of the twin rolls. . (3) A cooling fluid flow path is provided inside each of the twin rolls, and at least a portion of each roll outside the flow path is made of copper-based metal. The twin roll continuous casting machine according to item 2.