DE2415224C3 - Method and device for controlling the cooling capacity of narrow side walls in plate molds in continuous casting - Google Patents

Description

The invention relates to a method for controlling the cooling capacity of narrow side walls in plate molds in continuous casting, with the narrow side walls being clamped between broad side walls Start of casting the mold cavity between the narrow side walls with a converging in the direction of the strand, the steel quality and the strand width adapted pouring cone is provided and a Device for carrying out the method.

In the continuous casting of steel, a uniform as possible is achieved on all sides of the strand within the mold The aim is to dissipate heat so that the strand is as uniform as possible on all sides when it leaves the mold Crust thickness, ..

Due to the format-related different vibration values of the strand crust on the narrow and When casting slabs, broadsides are the contact between the strand surface and the narrow and broad side walls the mold unequal. In addition, the strand crust is also attached to the mold walls

by bulging, in particular of the broad sides affects It is customary to provide the narrow sides of the mold cavity having a converging in the direction of Kokillenausganges casting cone and execute the broad sides of the mold cavity in parallel or with ^ a with respect to the narrow sides of different casting cone.

There is known an adjustable Piattenkokille which simultaneously changed with the adjustment of the narrow side walls to different ribbon widths of the casting cone of the mold cavity between these walls for a predetermined in dependence of strand width shrinkage value The set casting cone, however, is optimal only for a small area of the casting speed and the casting temperature, , ₅ ie the application of the solidifying crust and thus the amount of heat dissipated can only be optimal with these values . If the casting speed and / or the casting temperature are changed, the shrinkage also changes, resulting in uneven cooling and solidification of the strand crust. Such irregularities lead to cracks and increase the risk of breakthrough and mold wear.

It is also an adjustable plate mold known that when adjusting the transverse walls to different Strand widths an automatic adjustment of the desired inclination of these transverse walls compared to a in the mold einlegbaien format setting gauge allows. The transverse walls are pivotably attached to and between yokes arranged transversely to the longitudinal walls springs are arranged on the transverse walls and rigid beams. This for a predetermined Casting speed and casting temperature adjustable mold results in changing casting parameters no even and optimal cooling.

There is also a plate mold known which is divided transversely to the strand direction into two parts, the upper part has no pouring cone and the walls of the lower part are resilient to the strand surface be pressed. Between the adjacent walls arranged in the lower part are Gaps are provided that allow the walls to move freely without interfering with one another. The on The spring force acting on these walls must on the one hand compensate for the force generated by the frost-static pressure withstand and on the other hand, the spring force must not deform the still thin strand crust. This Device is for casting with changing casting parameters, such as the casting speed and the casting temperature etc, unsuitable because the spring force affects different crust thicknesses or crust strengths is not customizable. Furthermore, such walls pressed by springs wear out very quickly. Additionally such narrow side walls can not be clamped between the broad sides, so that in the area of the Bath mirror an application of this device is excluded.

There is also a device for adjusting the format of a plate mold outside of the casting plant known, in which the narrow side walls of the mold were first moved without changing the pouring cone and fixed according to the desired strand format and then the pouring cone on the desired dimension is adjustable. With this device there is a uniform cooling with changing Casting parameters not provided during casting.

The invention has for its object to provide a method and an apparatus that have a optimal and even cooling within the mold with changing casting parameters, especially the Casting speed and the casting temperature. In addition, at high-performance continuous casters a casting with large casting speed differences with improved strand quality and reduced Risk of breakthrough be made possible.

According to the method according to the invention, this object is achieved in that before the start of casting Casting cone additionally to one of the envisaged casting speed and / or casting temperature corresponding Setpoint adjusted and in the event of a deviation from the casting speed and / or the casting temperature During the casting operation, the casting cone according to predetermined, these changing casting parameters corresponding setpoints is changed.

When using this process, it is possible to achieve optimal cooling conditions in plate molds the narrow side of the strand, even with strongly varying casting speeds, casting temperatures, etc. produce. As a result, there is in continuous slab casting plants for high casting speeds, for example about 2 m per min. the possibility of using one speed range during the same casting to run at less than 1 m per minute with a predetermined cooling capacity and strands with optimal quality and without Pour increased risk of breakthrough. The reasons for pouring at different pouring speeds in such plants are diverse. Examples are: slow casting, disturbances in the metal flow between intermediate vessel and the mold or pan and intermediate vessel, adjustment of the pouring time the converter cycle, reduced casting speed at the end of casting, etc.

The adjustment of the pouring cone during or shortly after the change in the pouring speed, the The casting temperature or other casting parameters influencing the solidification can be carried out according to various methods be performed. For example, it is possible to have an optimal target value for the conicity between the narrow side walls depending on the casting speed and / or the casting temperature to be determined by empirical tests. Such an optimal setpoint value is usually with respect to a Uniform solidification of the strand crust sought. The pouring cone can be set to predetermined, the adjusted target values corresponding to changed casting speed and / or the changed casting temperature will. In continuous casting practice, nominal values for the pouring cone »K« are given in ° / o per m.

It is also possible to use a desired setpoint cooling output value for the narrow side walls as a base value for the Fs Use cone setting. Both the casting temperature and the casting speed are Gießpa parameters that influence the cooling capacity of the mold walls. According to another characteristic de Invention, the cooling capacity of the Schmalseitenwän de measured continuously, these measured values with the ones the actual casting speed and / or the actual casting temperature corresponding target cooling output value and if there is a discrepancy between the target and The actual cooling capacity value of the pouring cone can be adjusted until the target cooling capacity is reached. In addition to de Casting speed and the casting temperature is the cooling capacity of the narrow side walls through the Strc mung in the liquid casting head, the type and amount of casting powder slag and by irregular cooling

^{Strand erzeu} affect 8 ^th bending component

20th

Another advantageous method for adapting the casting cone when changing a casting parameter influencing the cooling capacity of the narrow side wall can be achieved according to the invention if the specific cooling capacity of the narrow and wide side walls is continuously measured, the measured values of the narrow and wide side walls are mutually compared and the specific actual value -Cooling performance ratio between these walls see with the predetermined specific target Kuhüe.stung relationship discriminated and if there is a discrepancy between the specific target and actual cooling capacity ratio, the pouring cone is adjusted until the specific target cooling capacity ratio is reached The growth of the strand shell is controlled as a function of the sum of the casting parameters that are decisive for it. At the same time there are all casting parameters _and the like for uncontrollable influence factors such as expansions considered mnerhalb the mold or by SekundäSlun "generated bending moments in the line etc.

With given casting parameters, the target cone can be advantageously determined during the casting operation if the cooling capacity of the narrow side walls is continuously measured, when the pouring cone K changes, the cooling capacity deviation Δ Q (Kcal / cm? - see) after the cone deviation Δ K (% / m) differ-

TnL-ün ^{from the SO obtained} curve of the target cone associated with the target cow power value determines * "* '". ^{the Ri} * ^e l 'lie the values for S target cooling capacity or the target cone in the case of a differ

graced curve yf. which has a rising and a subsequent horizontal branch in the transition area between the rising 'and the' horizontal branch ^m

So that the force for adjusting the pouring cone of the mold cavity between the narrow side _{walls Aa} can be chosen to be minimal during a running casting and dimensionally stable slabs can be produced at different casting speeds and at the same time no adjustment of the strand guide immediately following the mold is necessary. can, according to a feature of the invention when adjusting the pouring cone, the dimension of the mold cavity corresponding to the nominal dimension of the strand at the mold exit between the narrow sides are retained th. The mold is _{equipped in the Re E} el so that the pivotable connection associated with the plate for the cone adjustment is determined by an axis running parallel to the narrow side walls, which is close to a plane formed by the mold exit. ^{6 g}

The force for moving the GieBkonus during GieBbetnebes can be kept relatively small and scratching of the copper plates of the wide side walls can be reduced if, according to one additional i _{st to,}

: hen feature of the invention, the force to clamp the narrow side walls during the adjustment 7 ·, «f about twice the value of the duS the " ^ "

Counterforce acting against errostatic pressure is reduced after the adjustment back to the value before the production is increased.

The device according to the invention I characterize that between the support frame and the . Narrow side wall a swiveling connected to this

30th

35

dene plate is arranged and that alternatively one of the two adjustment devices on the support frame and are attached to the plate and the other adjustment device to the plate and to the narrow side wall, The clamping force of the broad side walls can vary during the adjustment of the pouring cone Casting parameters remain unchanged and at the same time wear of the copper plates on the broad sides be avoided if, according to a feature of the invention, the cone adjusting device on the plate and on the narrow side wall and the device for adjusting the mold cavity to different ones Strand dimensions are attached to the plate and the support frame, with the narrow side wall The plate connected by the axis can be clamped between the broad side walls and that the width of the mold cavity The decisive dimension of the plate compared to the narrow side wall is up to 2 mm larger.

Another advantageous mold construction is characterized is characterized in that the Konusverstellcinrichtung on the plate and on the support frame, the device for Selling the mold cavity to different ones Strand dimensions are attached to the plate and to the narrow side wall and that the plate together with the narrow side wall are pivotable about the axis arranged on the support frame.

Further details and advantages of the invention can be found in the following description of the figures from FIG Examples can be found.

Show it

Fig. 1 is a plan view, partly in section, of a Part of a plate mold,

Fig. 2 shows a section along the line H-II in FIG. 1.

r ι g. 3 is a plan view of another example of a partially illustrated plate mold,

£ ι g- 4 a section along the line IV-IV of the l · ι ε. 3.

r 'g- 5 is a schematically illustrated plate mold with a control device and

kp ^ H ¹ ' ⁶ r> ^a _o ^{Diagramni of the} cooling capacity as a function of the pouring cone.

Stln ^d . ^{en Fig} "' ^{And 2 is} denoted by f ^a plate mold for continuous steel casting. A fixed 2 and a movable broad side wall 2' and narrow side walls 3 delimit the mold cavity 4. A narrow side wall 3 consists of a copper plate 7 facing the mold cavity 4 and a support plate 8 Walls 2, 2 ', 3 are supported in a support frame 5 that runs around the ivoiaile. By ^{means of} piston-cylinder units 6, the ends 3 are fixed between the broad sides 2, 2'

Messenger is

occur of the mold cavity 4 on the lower strand dimensions is on the narrow sides a plate 17 a device attached 'he spindle 11 and one with this spindle 11 ! Acting adjusting gear 12 consists. The ι «with the narrow side wall through a articulated. The adjusting gear 12 Had 17 fastened in turn with a connected to the support frame 5 is swivel plate 17 and the narrow side insertable Support gauges

6 ₅

of the casting cone, w hile the Gießbe-plate 17 and the supporting frame 5 is a ichtung arranged a spindle 21 variator 22 together is fixed to the ^fifth When moving the spindle

21 is the plate 17 together with the narrow side wall 3 by a transverse to the strand running direction 24 and Axis 25 running parallel to the narrow side walls 3 is pivoted. The axis 25 is close to the through the mold exit formed plane 27 and the adjusting mechanism 22 seen in the strand running direction 24 arranged in front of this axis 25. By this arrangement of the axis 25 can be achieved that when Adjustment of the pouring cone during the pouring operation by means of the adjustment gear 22 that corresponds to the nominal dimension of the Strand associated dimension 28 of the mold cavity 4 at the mold exit between the narrow sides practically can be maintained. The adjustment gears 12 and 22 are not shown with electrical Provide drives. Other adjustment devices, for example hydraulic ones, can be used.

In the F i g. 3 and 4 another solution is shown. The mold structure with respect to the support frame 5, the broad side walls 2, 2 'and the supported therein Piston-cylinder units 6 is the same as for FIG. 1 and 2 described.

To adjust the mold cavity in relation to the strand width, a spindle 32 is connected on the one hand to a plate 31 and on the other hand to the support frame 5. This spindle 32 can be driven by means of an adjusting gear 33. The adjusting gear 33 is attached to the support frame 5. Between the plate 31 and the support frame 5, the format-dependent setting and sleeve gauges 20 are suspended. An adjusting gear 35 is connected to the plate 31, which works together with a spindle 36 and serves to adjust the conicity of the mold cavity between the narrow side walls. The narrow side wall 3 is pivoted about an axis 37. The centerline of the axle 37 is located on the Kokillenausgangsebene 27. The shaft 37 connects the short side wall 3 hingedly connected to the wall between the narrow sides 3 and the supporting frame 5 disposed plate 31. The mold cavity width determining dimension 38 of the clamping walls 31 is opposite to the short side wall 3 to 7 mm larger. The clamping force generated by the piston-cylinder unit 6 is thus completely absorbed by the plate 31 when the mold is cold. The heating of the copper plate 7 during the casting operation closes the gap 39 that is present in the cold state of the mold, especially in the area of the bath surface. To avoid the penetration of steel splashes when pouring into the gap 39, the butt joint can be covered with adhesive tapes. A pivoting of the narrow side walls 3 during the casting operation is possible with this solution with low forces and without changing the contact pressure of the piston-cylinder units 6.

In Fig. 5 with 50 is a plate mold for slabs denotes which, as already described, essentially consists of the two broad side walls 2, 2 ' and composed of the two narrow side walls 3 The mold walls have cooling chambers 63-70, which include specific cooling areas. For the sake of simplicity, the cooling chambers are in the direction of travel of the strand not divided. If desired, the cooling capacity can be increased by dividing the cooling chambers can be measured and evaluated in a differentiated manner transversely to the direction of the strand. Each cooling chamber 63-70 are Water inflow and outflow lines 72 assigned to the water inflow and outflow lines 72 of the broad sides 2, 2 ' measuring elements 59 / for determining the amount of heat dissipated or the cooling capacity are connected. In the measuring elements 59 are at the same time an average value of the cooling capacity of the cooling chambers 63, 64 and 65, 66 is formed, which is fed to an averaging unit 55. The cooling capacity of the two cooling chambers 67.68 or 69.70 of the narrow side walls 3 is measured in measuring members 5Γ and 51 and as an average value 52, 52 'supplied to differential value formers 53, 54 and 53', 54 ', respectively. The difference value formers 53, 53 ' an output signal 74 of the averager 55 is also input. The difference value calculator 53, 53 'generate difference value signals 56, 56' which represent the difference between the cooling capacity of the corresponding These signals 56, 56 ′ are fed to a computer 58. the Difference value formers 54, 54 'generate difference value signals 57, 57', resulting from the actual cooling capacities the narrow sides and a signal 73 for the predetermined, the actual casting speed and / or the target cooling capacity of the narrow sides assigned to the actual casting temperature. The computer 58 can optionally mechanical actuators 60, 60 'for adjusting the conicity of the narrow sides either according to the signal 56 or control according to the signal 57. If the actuators 60, 60 'are controlled according to the signals 56, 56', the cooling capacity of the narrow side walls is continuously a predetermined one by changing the pouring cone Cooling performance ratio between the narrow and wide side walls adapted. This is a Uniform cooling performance ratio between the narrow and broad sides of the mold can be achieved. at With this method it is possible that a difference value 57, 57 'compared to a predetermined one of the casting speed etc. adjusted target cooling power value of the narrow sides is created. If the actuators 60,

3S 60 'is controlled according to the signals 57, 57', so The cooling capacity of the narrow side walls is continuously measured regardless of the cooling capacity of the broad sides and the pouring cone is set according to a predetermined target cooling capacity value. The every format associated cooling surfaces of the narrow and broad sides are entered in the computer 58, so that the specific Cooling performance in Kcal per cm · see continuously recalculated can be.

The computer can also use the mechanical actuator according to any combination of the two programs Control difference value signals 56 and 57.

The described devices for adjusting the pouring cone of the Sehmalseiiemvände during the pouring operation Different casting parameters work as follows: With a high-performance extrusion casting machine For example, if a sequence of several casts is to be cast. The strand format is 2000 χ 250 mm, the target continuous casting speed 2 m / min and the maximum continuous casting speed 2.5 / min. Before the start of casting, the pouring cone of the mold cavity, which converges in the pouring direction, is between the narrow side walls according to the approach speed of 1 m / min of the strand width and the steel quality set to 0.9% per m. The mentioned pouring cone »K« in% per m is used according to the calculated using the following formula:

% K per m =

IB
Bw

100

Δ B is the difference in mm between the upper and the lower width of the conical Formhtlraumes 4, Bu the measure in mm of the smaller width of the

709 608 317

Mold cavity 4 and L is the height in m of the mold cavity 4. After uncoupling the start-up strand, the pouring cone should be adjusted to a level corresponding to the target continuous casting speed of 2 m / min while the pouring is in progress. For this purpose, before the adjustment, the clamping force acting on the broad side walls 2 'is reduced to about twice the value of the counterforce acting on the broad side walls due to the ferrostatic pressure. The conicity of the narrow side walls is now changed at the same time as the casting speed is increased to 2 m / min to a casting cone of 0.5% per m. After the adjustment, the clamping force is increased again to at least 5 times the value of the counterforce acting on the broad side walls

When using a mold according to FIGS. 3 and 4 is a reduction in the clamping force during the Adjustment of the pouring cone is not necessary.

In the case of molds that are equipped with devices for measuring the cooling capacity in the narrow side walls are, after the adjustment of the pouring cone to the changed pouring speed, the actual cooling performance values the two narrow sides to me. the target cooling power value predetermined for the changed casting speed be compared. If the actual and target values do not match, the received deviation signal is used to set the pouring cone on one or both Adjusted narrow sides.

Further adjustments of the pouring cone are for example necessary if for any reason, for example as a result of a plug runner, during a certain time must be poured at the maximum casting speed of 2.5 m / min. In front At the end of pouring, the pouring speed is gradually increased to about 0.8 lpm / min while adjusting the Pouring cone reduced to a value of 0.8 - 0.9% per m.

Becomes the pouring cone of a changed pouring temperature adjusted, this is done in the same manner as when changing the casting speed. A higher casting temperature retards the solidification of the strand crust in the mold similar to a higher casting speed. The cooling capacity of the narrow side walls is increased. The adaptation of the pouring cone thus requires a reduction in size when the pouring temperature is increased or when it is decreased the casting temperature an increase in

ίο taper.

The optimal pouring cone K (target value) of the pouring cone during the pouring operation can be determined as follows as a function of all the pouring parameters involved, such as pouring speed, pouring temperature, strand format, steel quality, type of pourable powder slag, etc. 6, the cooling capacity Q (Kcal / cm ² ■ see) is plotted on the vertical and the cone K (in% per m) plotted on the horizontal, so in section 80 with increasing cone K the cooling capacity curve 85 rises from cone = zero to higher Cooling performance values and then turns into an approximately horizontal curve in section 81. The optimal cone K (good cooling performance and relatively little wear) lies in the

Usually in the transition curve in section 81 from the rising to the horizontal curve branch in the section 82. The drawn curve 85 is only for an example! valid because depending on the type of mold and the Casting parameters can deviate from the curve shown.

By differentiating the deviations ^ -Q- is the

Quickly determine the desired curve area during the casting operation. With one at the continuous caster connected computer can also automatically optimize the cooling performance depending on the cone taking into account all of the cooling acting casting parameters can be determined.

For this purpose 3 sheets of drawings

Claims (11)

Patent claims: 1. A method for controlling the cooling capacity of narrow side walls in plate molds during continuous casting, the narrow side walls being clamped between broad side walls, before the start of casting the mold cavity between the narrow side walls is provided with a casting cone which converges in the direction of the strand and is adapted to the steel quality and the strand width, characterized in that before The pouring start of the pouring cone is additionally adjusted to a setpoint corresponding to the envisaged pouring speed and / or pouring temperature and, ₅ if there is a deviation from the pouring speed and / or the pouring temperature during the pouring operation, the pouring cone is changed according to predetermined setpoints corresponding to these changing pouring parameters. 2. The method according to claim 1, characterized in that that the cooling capacity of the narrow side walls is continuously measured, these measured values with that the target cooling power value corresponding to the actual casting speed and / or the actual casting temperature compared and if there is a discrepancy between the target and the actual cooling capacity value, the pouring cone is up to Reaching the target cooling capacity is changed. 3. The method according to claim 1, characterized in that the specific cooling capacity of the ^ ₀ narrow and wide side walls is continuously measured, these measured values of the narrow and wide side walls are compared with each other and the specific actual cooling capacity ratio between these walls with the predetermined specific target cooling capacity ^ ratio discriminated and in the event of a deviation between the specific target and actual cooling performance ratio, the pouring cone is changed until the specific target cooling performance ratio is reached. 4. The method according to any one of claims 1 to 3, characterized in that the cooling capacity of the narrow side walls is measured continuously, with a change in the pouring cone K the deviation in the cooling capacity Δ Q (Kcal / cm ² · see) after the deviation of the cone Δ K (% / m) and from the curve obtained in this way, the target cone associated with the target cooling output value is determined. 5. The method according to claim 4, characterized in that with a differentiated curve Δ Q / Δ K, which has a rising and a subsequent horizontal branch, the values for the target cooling capacity and the target cone are selected from the transition area between rising and horizontal branch. 6. The method according to any one of claims 1 to 5, characterized in that when adjusting the Pouring cone the dimension of the mold cavity at the mold outlet corresponding to the nominal dimension of the strand is maintained between the narrow sides. 7. The method according to any one of claims 1 to 6, characterized in that the force for Clamping of the narrow side walls during the adjustment to about twice the value of the through the ferrostatic pressure acting counterforce is reduced and after the adjustment again on the Value is increased before the adjustment. 8. plate mold for performing the method according to any one of claims 1 to 7. wherein the Narrow side walls that can be clamped between the broad side walls with devices for adjustment of the mold cavity to different strand dimensions and with devices for adjustment of the pouring cone are provided, characterized in that between the support frame (5) and the Narrow side wall (3) a plate (17.31) pivotally connected to this is arranged and that alternatively one of the two adjustment devices (21, 22 or 32, 33) on the support frame (5) and the plate (17 or 31) and the other adjustment device (11, 12 or 35, 36) on the plate (17 or 31) and the Narrow side wall (3) are attached. 9. plate mold according to claim 8, characterized in that the plate (17, 31) for the Conical adjustment associated pivotable connection by a parallel to the narrow side walls (3) extending axis (25, 37) is determined, which is close to one formed by the mold exit Level (27) lies. 10. Plat'enkokille according to claim 8 or 9, characterized characterized in that the cone adjusting device (35, 36) on the plate (31) and on the narrow side wall (3) and the device (32, 33) for adjusting the mold cavity (4) to different strand dimensions are attached to the plate (31) and to the support frame (5), with the narrow side wall (3) The plate (31) connected by the axis (37) can be clamped between the broad side walls (2, 2 ') and the dimension (38) of the plate (31) relative to the narrow side wall, which determines the width of the mold cavity (3) is up to 2 mm larger. 11. plate mold according to claim 8 or 9, characterized characterized in that the cone adjustment device (21,22) on the plate (17) and on the support frame (5), the Device (11, 12) for adjusting the mold cavity (4) to different strand dimensions are attached to the plate (17) and to the SchmaJseitenwand (3) and that the plate (17) together with the narrow side wall (3) can be pivoted about the axis (25) arranged on the support frame (5).