CA2098572C - Casting process for continuous castings - Google Patents
Casting process for continuous castingsInfo
- Publication number
- CA2098572C CA2098572C CA002098572A CA2098572A CA2098572C CA 2098572 C CA2098572 C CA 2098572C CA 002098572 A CA002098572 A CA 002098572A CA 2098572 A CA2098572 A CA 2098572A CA 2098572 C CA2098572 C CA 2098572C
- Authority
- CA
- Canada
- Prior art keywords
- mold
- casting
- solidified shell
- period
- wall surfaces
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/053—Means for oscillating the moulds
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
Abstract
In a process of withdrawing castings while vertically oscillating a mold formed with long side walls and short side walls in vertical continuous casting, the long side walls are separated from the castings by operating a hydraulic cylinder 4 in the time zones for which the castings are applied with a large frictional force. On the contrary, the separated long side walls are made close to the castings in the other time zones for which the castings are not applied with the large frictional force. By repeating the separation and approaching of the long side walls, it is possible to obtain the castings reduced in the depths of oscillation marks and suppressed in segregations at oscillation mark trough portions.
Description
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DESCRIPTION
CASTING PROCESS FOR CONTINUOUS CASTINGS
Technical Field The present invention relates to a casting process for continuous castings, capable of obtaining the castings reduced in the depths of oscillation marks and suppressed in segregation at oscillation mark trough portions, in a continuous casting method, particularly, a vertical continuous casting method for metal.
Background Art Conventionally, for the purpose of eliminating 1 the repairing work for the surfaces of continuous castings, there has been proposed a technique of oscillating a vertical meld for reducing or preventing positive segregations at oscillation mark trough portions on the surfaces o.f the castings, particularly, in casting stainless steel (SUS 304). For example, Japanese Patent Laid-open No. hei 2-?_90656 has disclosed such a technique that, in a continuous casting mold of a type forming a casting space with two pairs of mold wall surfaces, a pair of the mold wall surfaces are relatively separated from each other only for a negative ~~9~~~2 strip time zone in vertical oscillation or for a mold descending time zone.
This technique is recognized to be considerably effective as compared with a case of giving only simple vertical oscillation. However, as a result of an experiment, it is seen that the technique is not much effective for such a case that the oscillation frequency <f> of the mold is small. Further, in the above technique, the consumption of mold powder is reduced, thereby causing the breakaut due to sticking.
accordingly, on the contrary, there is arisen an inconvenience of obstructing the stable casting.
Conventionally, the mechanism and cause of generating the segregations at oscillation mark trough portions were considered as follows: namely, the negative pressure is generated within a liquid phase lubricating film between the mold and the solidified shell due to oscillation of the mold; and due to this negative pressure, the non-solidified and concentrated molten steel between dendrites of the solidified surface layer permeates onto the surface of the shell.
However, as a result of the examination on the segregated portions of the casting by the present inventors, it was revealed that the segregation is generated in accordance with such a mechanism that the continuous growth of the solidified shell is obstructed ~0~~~'~2 by breaking of the shell due to a tensile force applied thereto and by buckling due to a compressive force, and thereby the concentrated liquid flows out from the broken portions or buckled portions of the shell to the surface of the shell. Accordingly, for preventing the segregation, it is effective to prevent the breaking or the buckling of the shell at the beginning of the solidification, that is, to simultaneously reduce the tensile force and the compressive force applied to the shell.
An object of the present invention is to provide a process of withdrawing the continuous castings wherein, even in the low cycle condition that the oscillation frequency <f> of the mold is small, the segregations at oscillation mark trough portions on the surfaces of the castings are significantly reduced to the degree equivalent to that in the high cycle condition, and also the stable casting is made possible.
Disclosure of the Invention In a preferred mode of the present invention, there is provided a casting process for continuous castings characterized by vertically oscillating a vertical continuous casting mold forming a casting space with two pairs of mold wall surfaces; and simultaneously repeating a series of actions composed of separating at least a pair of mold wall surfaces from a solidified shell at any period in each specified time zone within a positive strip time zone and a negative strip time zone, and of making the separated mold wall surfaces close to the solidified shell within the other time zones.
Further, preferably, there is provided a casting process .for continuous castings characterized by performing the casting under the condition of only a positive strip time zone, while vertically oscillating a vertical continuous casting mold forming a casting space with two pairs of mold wall surfaces; and repeating a series of actions composed of separating at least a pair of mold wall surfaces from a solidified shell at any,period in each specified time zone within a mold ascending period and a mold descending period, and making the separated mold wall surfaces close to the solidified shell within the other time zones in the mold ascending period and the descending period Brief Description of the Drawings Fig. 1 is a graph showing the changes in the vertical oscillating velocity of a mold and the horizontal displacement of the mold walls with time according to an embodiment of the present invention;
Fig. 2 is a graph showing the changes in the vertical oscillating velocity of a mold and the horizontal displacement of the: mold walls with time according to another embodiment of the present invention;
Fig. 3 is. a schematic perspective view showing a mold horizontally moving apparatus used in the embodiments of the present invention;
Fig. 4 is a typical view showing an oscillation mark and a segregated layer;
Fig. 5 is graphs showing an oscillation waveform of the conventional mold, and the retarding and advancing timings thereof; and Fig. 6 is a typical view showing the portion between the mold wall and the solidified shell.
Best Mode for Carrying Out the Invention As shown in Fig. 1, the vertical velocity Vm of the mold follows a sine curve relative to time. When the mold reaches the uppermost point, the vertical velocity Vm of the mold becomes 0. Subsequently, as the mold starts to descend, the velocity Vm gradually increases. Thus, when the mold reaches the lowermost point, the velocity Vm becomes 0. When the mold starts to ascend again, the velocity Vm of the mold increases. Also, in terms of the relative relationship between the vertical velocity Vm of the mold and the withdrawing velocity Vc of the casting, the time zone in which the vertical velocity Vm of the mold is smaller than the withdrawing velocity Vc is referred to as "a negative strip time TN" and the time zone in which the vertical velocity Vm of the mold is larder than the withdrawing velocity Vc is referred to as "a positive strip time Tp°.
In vertical oscillation of the mold as shown in Fig.
1, at any period in a time zone from the time tl to t2 for which the relative velocity (=Vm-Vc) is larger within a positive strip time Tp for which the solidified shell is applied with a tensile force, at least one pair of the mold walls are horizontally retarded in a manner to be relatively separated from the solidified shell, to be thus opened at the l0 position Xo. When the negative strip time TN (TN = 0) does not exist, as shown. in Fig. 2, at any period in a time zone from the time t4 to t5 for which the relative velocity is larger within a mold ascending period, at least one pair of the mold walls are retarded in a manner to be relatively separated from the solidified shell, to be thus opened at the position Xo.
Thus, as shown in Fig. 6, a distance between a mold wall 9 and a solidified shell 12 is increased from Xs to Xo, so that a mold powder 10 on a molten steel 11 is made to 20 sufficiently flow in a gap between the mold wall 9 and the solidified shell 12 to thereby reduce the frictional force between the mold wall 9 and the solidified shell 12. In addition, the arrow of Y indicates the direction of withdrawing the casting.
In Fig. 1, at any period in a subsequent time zone from the time t3 to t4 for which the relative velocity is smaller within the negative strip time TN for which the compressive force is applied to the shell, the mold walls are relatively separated from the solidified shell, to be thus opened at the position Xo. When there is no negative strip time TN (TN=0), as shown in Fig. 2, at any period in a time zone from the time t2 to t3 for which the relative velocity is smaller in a mold descending time, at least one pair of the mold walls are retarded in a manner to be relatively separated from the solidified. shell, to be thus opened at the position Xo. When there is no negative strip time TN, since the relative velocity between the mold and the solidified shell is usually directed upwardly, it is considered that the shell is not applied with th.e compressive force. However, since the solidified shell at a meniscus portion within the mold continuously grows and the position thereof is made constant, the shell is applied with the compressive force even in the case of TN=0.
For the time zones other than those described above, that is, for the time zones from the time t2 to t3 and from the time t4 to t5 in Fig. 1, and the time zones from the time tl to t2 and from the time t3 to t4 in Fig. 2, the mold walls are advanced to be close to the solidified ~~hell, to be thus closed at the position Xs. Namely, the distance X between the mold and the solidified shell is changed from Xo to Xs. In the case of giving the horizontal oscillation to the mold for.
changing the distance between the mold wall surfaces and the solidified shell, particularly, the frictional force applied tv the initial solidified shell of the meniscus portion can be calculated, under the consideration of the frictional force between the mold and the solidified shell, as the shear force applied between the mold and the solidified shell by the following equation:
F - A ~ ~.t (dV / dX) . . . ( 1 ) wherein A . contact area between mold and solidified shell viscosity of mold powder flown in space between mald wall and solidified shell dV: relative velocity between mold wall and solidified shell (=Vm-Vc) X . dist;ance between mold and solidified shell As is apparent from the above equation (1), the frictional force F applied to the solidified shell is reduced during a period for which the distance X between the mold and the solidified shell is enlarged. Namely, according to the present invention, it is possible to significantly reduce the tensile force and the compressive force applied to the shell of the meniscus portion at the beginning of the solidification.
Consequently, the continuity of the solidified shell is held, thereby making it possible to narrow the depths of the oscillation marks, and to reduce the possibility of generating the. segregation at the oscillation mark trough portions as compared with the conventional technique.
The effect describe above is not much dependent on the vertical oscillation waveform and a waveform for horizontally advancing/retarding (elosing/opening) the mold walls (hereinafter, referred to as '°horizontal oscillation"), and which is similarly effective in the cases of the non-sinusoidal wave or triangular wave other than the vertical oscillation of the sinusoidal wave and the horizontal wave of the trapezoidal wave as shown in Fig. 1. In addition, for preventing molten steel from permeating in the gaps at the mold corners thereby bringing about a fear of causing the sticking induced breakout, the amplitude of the horizontal oscillation is preferably within the range of 1mm or less.
Hereinafter, the present invention will be described in detail with reference to examples.
Example 1 As shown in Fig. 3, a horizontal oscillator generally used for a slab continuous casting machine has a mechanism of clamping mold short sides 2 with mold long sides t through short side clamping springs 3. In the present invention, there is provided a hydraulic circuit for opening/closing a short side clamping hydraulic cylinder 4, so that 'the long sides 1 of the mold is moved by opening and closing the short side clamping hydraulic cylinder 4 through upper and lower solenoid valves 5 and 6 provided in a hydraulic circuit. Numeral 7 indicates a hydraulic motor and numeral $ is a hydraulic tank. If the gaps between the long sides and short sides of the mold are made excessively larger, molten steel permeates in the gaps, thereby causing the trouble. Accordingly, the retarded amount of the long sides of the mold is within the range of 1mm or less.
The casting of stainless steel (SUS 304) was continuously cast using the above horizontal oscillator for horizontally oscillating the mold walls as shown in Fig. 3. In the above casting, from the depth d,, at an oscillation mark 13 (see Fig. 4) and the segregation layer depth d2 at the segregation mark portion on the surface of the casting, the segregation layer thickness (d2 -dl) at the oscillation mark portion was obtained.
Thus, the examination was made for the above segregation layer thickness (d2 -dl) and the segregation layer a depth d2. For comparison, the examinations were made for the cases of generating only the vertical oscillation (sinusoidal wave) according to the conventional manner; and of generating such oscillating waves as shown in Figs. 5(a) and 5(b) disclosed in Japanese Fatent Laid-open No. Hei 2-290656. In the above, Fig. 5(a) shows the case of moving the mold walls backward during the period when the oscillation of the mold lies in the negative strip time. Besides, Fig. 5(b) shows the case of retarding the mold in the mold descending period. In addition, the casting condition of the present invention is as follows:
withdrawing velocity Vc of castings= 1.2/min; mold vertical oscillating frequency f = 150 times/min;
amplitude S = 5-3mm; vertical oscillating waveform =
sinusoidal curve; horizontal oscillating amplitude =0.3mm; horizontal oscillating pattern is trapezoidal wave (see Fig. 1). Further, the mold wall opening/closing timing is closed (at the position of Xs) for a period from 105 ° to 130 ° (from the time t2 to t3 in Fig. 1) in terms of angle conversion (zero angle, when U m is positively maximized), and a period from 240° to 275 ° (from the time t4 to t5 in Fig. 1), and is opened (at the position of Xo) for the other periods. The moving velocity from the opening to the closing, or the closing to the opening was specified at 50mm/sec. In addition, as the mold power, there was used a lubricant having a viscosity of 1.1 poise at 1300 ° C and the solidification temperature of 900° C.
Example 2 Next, for the case of no negative strip time (T N 0), the test was carried out in the same manner as in Example 1, except that the amplitude S of the mold vertical oscillation was 2.Omm, and the horizontal opening and closing timing caas closed in the period from 110 ° to 160 ° (from the time t1 to t2 in Fig.
2) and in a period from 250° to 290 ° (from the time t3 to t4 in Fig. 2), and was opened in the other periods.
The results obtained in Examples 1 and 2 are shown in Table 1 as compared with the conventional manner. It becomes apparent from Table 1 that, as compared with the conventional manner, the present invention makes it possible to significantly .reduce the rate of generating the segregations at the oscillation trough portions to the degree of being almost zero. .
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Industrial Applicability By provision of a mold oscillation method of horizontally opening and closing (retarding and advancing) the mold walls from and to the solidified shell according to the mold vertical oscillating timing for extremely reducing the compressive force and the tensile force applied to the initial solidified shell, it is possible to significantly reduce the segregations at the oscillation trough portions on the surface of the casting. As a result, the following effects can be obtained:
(1) By eliminating the need of performing the casting under the high cycle mold oscillating condition having a fear of causing. the generation of the sticking induced breakout, it is possible to reduce the. trouble in productivity.
(2) In the case of stainless. steel (SUS 30~), sihce it is possible to reduce the amount to be cut by a grinder for removing the segregations before the heating and rolling processes as in the conventional manner, and further to supply the casting to the next process with no repairing in the specific case, the improvement in yield can be expected.
DESCRIPTION
CASTING PROCESS FOR CONTINUOUS CASTINGS
Technical Field The present invention relates to a casting process for continuous castings, capable of obtaining the castings reduced in the depths of oscillation marks and suppressed in segregation at oscillation mark trough portions, in a continuous casting method, particularly, a vertical continuous casting method for metal.
Background Art Conventionally, for the purpose of eliminating 1 the repairing work for the surfaces of continuous castings, there has been proposed a technique of oscillating a vertical meld for reducing or preventing positive segregations at oscillation mark trough portions on the surfaces o.f the castings, particularly, in casting stainless steel (SUS 304). For example, Japanese Patent Laid-open No. hei 2-?_90656 has disclosed such a technique that, in a continuous casting mold of a type forming a casting space with two pairs of mold wall surfaces, a pair of the mold wall surfaces are relatively separated from each other only for a negative ~~9~~~2 strip time zone in vertical oscillation or for a mold descending time zone.
This technique is recognized to be considerably effective as compared with a case of giving only simple vertical oscillation. However, as a result of an experiment, it is seen that the technique is not much effective for such a case that the oscillation frequency <f> of the mold is small. Further, in the above technique, the consumption of mold powder is reduced, thereby causing the breakaut due to sticking.
accordingly, on the contrary, there is arisen an inconvenience of obstructing the stable casting.
Conventionally, the mechanism and cause of generating the segregations at oscillation mark trough portions were considered as follows: namely, the negative pressure is generated within a liquid phase lubricating film between the mold and the solidified shell due to oscillation of the mold; and due to this negative pressure, the non-solidified and concentrated molten steel between dendrites of the solidified surface layer permeates onto the surface of the shell.
However, as a result of the examination on the segregated portions of the casting by the present inventors, it was revealed that the segregation is generated in accordance with such a mechanism that the continuous growth of the solidified shell is obstructed ~0~~~'~2 by breaking of the shell due to a tensile force applied thereto and by buckling due to a compressive force, and thereby the concentrated liquid flows out from the broken portions or buckled portions of the shell to the surface of the shell. Accordingly, for preventing the segregation, it is effective to prevent the breaking or the buckling of the shell at the beginning of the solidification, that is, to simultaneously reduce the tensile force and the compressive force applied to the shell.
An object of the present invention is to provide a process of withdrawing the continuous castings wherein, even in the low cycle condition that the oscillation frequency <f> of the mold is small, the segregations at oscillation mark trough portions on the surfaces of the castings are significantly reduced to the degree equivalent to that in the high cycle condition, and also the stable casting is made possible.
Disclosure of the Invention In a preferred mode of the present invention, there is provided a casting process for continuous castings characterized by vertically oscillating a vertical continuous casting mold forming a casting space with two pairs of mold wall surfaces; and simultaneously repeating a series of actions composed of separating at least a pair of mold wall surfaces from a solidified shell at any period in each specified time zone within a positive strip time zone and a negative strip time zone, and of making the separated mold wall surfaces close to the solidified shell within the other time zones.
Further, preferably, there is provided a casting process .for continuous castings characterized by performing the casting under the condition of only a positive strip time zone, while vertically oscillating a vertical continuous casting mold forming a casting space with two pairs of mold wall surfaces; and repeating a series of actions composed of separating at least a pair of mold wall surfaces from a solidified shell at any,period in each specified time zone within a mold ascending period and a mold descending period, and making the separated mold wall surfaces close to the solidified shell within the other time zones in the mold ascending period and the descending period Brief Description of the Drawings Fig. 1 is a graph showing the changes in the vertical oscillating velocity of a mold and the horizontal displacement of the mold walls with time according to an embodiment of the present invention;
Fig. 2 is a graph showing the changes in the vertical oscillating velocity of a mold and the horizontal displacement of the: mold walls with time according to another embodiment of the present invention;
Fig. 3 is. a schematic perspective view showing a mold horizontally moving apparatus used in the embodiments of the present invention;
Fig. 4 is a typical view showing an oscillation mark and a segregated layer;
Fig. 5 is graphs showing an oscillation waveform of the conventional mold, and the retarding and advancing timings thereof; and Fig. 6 is a typical view showing the portion between the mold wall and the solidified shell.
Best Mode for Carrying Out the Invention As shown in Fig. 1, the vertical velocity Vm of the mold follows a sine curve relative to time. When the mold reaches the uppermost point, the vertical velocity Vm of the mold becomes 0. Subsequently, as the mold starts to descend, the velocity Vm gradually increases. Thus, when the mold reaches the lowermost point, the velocity Vm becomes 0. When the mold starts to ascend again, the velocity Vm of the mold increases. Also, in terms of the relative relationship between the vertical velocity Vm of the mold and the withdrawing velocity Vc of the casting, the time zone in which the vertical velocity Vm of the mold is smaller than the withdrawing velocity Vc is referred to as "a negative strip time TN" and the time zone in which the vertical velocity Vm of the mold is larder than the withdrawing velocity Vc is referred to as "a positive strip time Tp°.
In vertical oscillation of the mold as shown in Fig.
1, at any period in a time zone from the time tl to t2 for which the relative velocity (=Vm-Vc) is larger within a positive strip time Tp for which the solidified shell is applied with a tensile force, at least one pair of the mold walls are horizontally retarded in a manner to be relatively separated from the solidified shell, to be thus opened at the l0 position Xo. When the negative strip time TN (TN = 0) does not exist, as shown. in Fig. 2, at any period in a time zone from the time t4 to t5 for which the relative velocity is larger within a mold ascending period, at least one pair of the mold walls are retarded in a manner to be relatively separated from the solidified shell, to be thus opened at the position Xo.
Thus, as shown in Fig. 6, a distance between a mold wall 9 and a solidified shell 12 is increased from Xs to Xo, so that a mold powder 10 on a molten steel 11 is made to 20 sufficiently flow in a gap between the mold wall 9 and the solidified shell 12 to thereby reduce the frictional force between the mold wall 9 and the solidified shell 12. In addition, the arrow of Y indicates the direction of withdrawing the casting.
In Fig. 1, at any period in a subsequent time zone from the time t3 to t4 for which the relative velocity is smaller within the negative strip time TN for which the compressive force is applied to the shell, the mold walls are relatively separated from the solidified shell, to be thus opened at the position Xo. When there is no negative strip time TN (TN=0), as shown in Fig. 2, at any period in a time zone from the time t2 to t3 for which the relative velocity is smaller in a mold descending time, at least one pair of the mold walls are retarded in a manner to be relatively separated from the solidified. shell, to be thus opened at the position Xo. When there is no negative strip time TN, since the relative velocity between the mold and the solidified shell is usually directed upwardly, it is considered that the shell is not applied with th.e compressive force. However, since the solidified shell at a meniscus portion within the mold continuously grows and the position thereof is made constant, the shell is applied with the compressive force even in the case of TN=0.
For the time zones other than those described above, that is, for the time zones from the time t2 to t3 and from the time t4 to t5 in Fig. 1, and the time zones from the time tl to t2 and from the time t3 to t4 in Fig. 2, the mold walls are advanced to be close to the solidified ~~hell, to be thus closed at the position Xs. Namely, the distance X between the mold and the solidified shell is changed from Xo to Xs. In the case of giving the horizontal oscillation to the mold for.
changing the distance between the mold wall surfaces and the solidified shell, particularly, the frictional force applied tv the initial solidified shell of the meniscus portion can be calculated, under the consideration of the frictional force between the mold and the solidified shell, as the shear force applied between the mold and the solidified shell by the following equation:
F - A ~ ~.t (dV / dX) . . . ( 1 ) wherein A . contact area between mold and solidified shell viscosity of mold powder flown in space between mald wall and solidified shell dV: relative velocity between mold wall and solidified shell (=Vm-Vc) X . dist;ance between mold and solidified shell As is apparent from the above equation (1), the frictional force F applied to the solidified shell is reduced during a period for which the distance X between the mold and the solidified shell is enlarged. Namely, according to the present invention, it is possible to significantly reduce the tensile force and the compressive force applied to the shell of the meniscus portion at the beginning of the solidification.
Consequently, the continuity of the solidified shell is held, thereby making it possible to narrow the depths of the oscillation marks, and to reduce the possibility of generating the. segregation at the oscillation mark trough portions as compared with the conventional technique.
The effect describe above is not much dependent on the vertical oscillation waveform and a waveform for horizontally advancing/retarding (elosing/opening) the mold walls (hereinafter, referred to as '°horizontal oscillation"), and which is similarly effective in the cases of the non-sinusoidal wave or triangular wave other than the vertical oscillation of the sinusoidal wave and the horizontal wave of the trapezoidal wave as shown in Fig. 1. In addition, for preventing molten steel from permeating in the gaps at the mold corners thereby bringing about a fear of causing the sticking induced breakout, the amplitude of the horizontal oscillation is preferably within the range of 1mm or less.
Hereinafter, the present invention will be described in detail with reference to examples.
Example 1 As shown in Fig. 3, a horizontal oscillator generally used for a slab continuous casting machine has a mechanism of clamping mold short sides 2 with mold long sides t through short side clamping springs 3. In the present invention, there is provided a hydraulic circuit for opening/closing a short side clamping hydraulic cylinder 4, so that 'the long sides 1 of the mold is moved by opening and closing the short side clamping hydraulic cylinder 4 through upper and lower solenoid valves 5 and 6 provided in a hydraulic circuit. Numeral 7 indicates a hydraulic motor and numeral $ is a hydraulic tank. If the gaps between the long sides and short sides of the mold are made excessively larger, molten steel permeates in the gaps, thereby causing the trouble. Accordingly, the retarded amount of the long sides of the mold is within the range of 1mm or less.
The casting of stainless steel (SUS 304) was continuously cast using the above horizontal oscillator for horizontally oscillating the mold walls as shown in Fig. 3. In the above casting, from the depth d,, at an oscillation mark 13 (see Fig. 4) and the segregation layer depth d2 at the segregation mark portion on the surface of the casting, the segregation layer thickness (d2 -dl) at the oscillation mark portion was obtained.
Thus, the examination was made for the above segregation layer thickness (d2 -dl) and the segregation layer a depth d2. For comparison, the examinations were made for the cases of generating only the vertical oscillation (sinusoidal wave) according to the conventional manner; and of generating such oscillating waves as shown in Figs. 5(a) and 5(b) disclosed in Japanese Fatent Laid-open No. Hei 2-290656. In the above, Fig. 5(a) shows the case of moving the mold walls backward during the period when the oscillation of the mold lies in the negative strip time. Besides, Fig. 5(b) shows the case of retarding the mold in the mold descending period. In addition, the casting condition of the present invention is as follows:
withdrawing velocity Vc of castings= 1.2/min; mold vertical oscillating frequency f = 150 times/min;
amplitude S = 5-3mm; vertical oscillating waveform =
sinusoidal curve; horizontal oscillating amplitude =0.3mm; horizontal oscillating pattern is trapezoidal wave (see Fig. 1). Further, the mold wall opening/closing timing is closed (at the position of Xs) for a period from 105 ° to 130 ° (from the time t2 to t3 in Fig. 1) in terms of angle conversion (zero angle, when U m is positively maximized), and a period from 240° to 275 ° (from the time t4 to t5 in Fig. 1), and is opened (at the position of Xo) for the other periods. The moving velocity from the opening to the closing, or the closing to the opening was specified at 50mm/sec. In addition, as the mold power, there was used a lubricant having a viscosity of 1.1 poise at 1300 ° C and the solidification temperature of 900° C.
Example 2 Next, for the case of no negative strip time (T N 0), the test was carried out in the same manner as in Example 1, except that the amplitude S of the mold vertical oscillation was 2.Omm, and the horizontal opening and closing timing caas closed in the period from 110 ° to 160 ° (from the time t1 to t2 in Fig.
2) and in a period from 250° to 290 ° (from the time t3 to t4 in Fig. 2), and was opened in the other periods.
The results obtained in Examples 1 and 2 are shown in Table 1 as compared with the conventional manner. It becomes apparent from Table 1 that, as compared with the conventional manner, the present invention makes it possible to significantly .reduce the rate of generating the segregations at the oscillation trough portions to the degree of being almost zero. .
.
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Industrial Applicability By provision of a mold oscillation method of horizontally opening and closing (retarding and advancing) the mold walls from and to the solidified shell according to the mold vertical oscillating timing for extremely reducing the compressive force and the tensile force applied to the initial solidified shell, it is possible to significantly reduce the segregations at the oscillation trough portions on the surface of the casting. As a result, the following effects can be obtained:
(1) By eliminating the need of performing the casting under the high cycle mold oscillating condition having a fear of causing. the generation of the sticking induced breakout, it is possible to reduce the. trouble in productivity.
(2) In the case of stainless. steel (SUS 30~), sihce it is possible to reduce the amount to be cut by a grinder for removing the segregations before the heating and rolling processes as in the conventional manner, and further to supply the casting to the next process with no repairing in the specific case, the improvement in yield can be expected.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A castings process for a continuous casting, which comprises:
casting a molten steel into a casting space of a vertical continuous casting mold having two pairs of mold wall surfaces, while vertically oscillating the casting mold; and simultaneously repeating a series of actions composed of separating at least one pair of the mold wall surfaces from a solidified shell during any specified period of time in each of a positive strip time zone and a negative strip time zone, and making the separated mold wall surfaces close to the solidified shell during another period of time in each of the positive and negative time zones.
casting a molten steel into a casting space of a vertical continuous casting mold having two pairs of mold wall surfaces, while vertically oscillating the casting mold; and simultaneously repeating a series of actions composed of separating at least one pair of the mold wall surfaces from a solidified shell during any specified period of time in each of a positive strip time zone and a negative strip time zone, and making the separated mold wall surfaces close to the solidified shell during another period of time in each of the positive and negative time zones.
2. A casting process for a continuous casting, which comprises:
casting a molten steel into a casting space of a continuous casting mold having two pairs of mold wall surfaces, while vertically oscillating the casting mold under such conditions that there is only a positive strip time zone;
and simultaneously repeating a series of actions composed of separating at least one pair of the mold wall surfaces from a solidified shell during any specified period of time in each of a mold ascending period and a mold descending period, and making the separated mold wall surfaces close to the solidified shell during another period of time in each of the mold ascending and descending period.
casting a molten steel into a casting space of a continuous casting mold having two pairs of mold wall surfaces, while vertically oscillating the casting mold under such conditions that there is only a positive strip time zone;
and simultaneously repeating a series of actions composed of separating at least one pair of the mold wall surfaces from a solidified shell during any specified period of time in each of a mold ascending period and a mold descending period, and making the separated mold wall surfaces close to the solidified shell during another period of time in each of the mold ascending and descending period.
3. A continuous casting process for a casting from molten steel, which. comprises:
casting the molten steel into a casting space of a vertical continuous casting mold having two pairs of vertical mold wall surfaces, thereby forming a solidified shell of the steel on each vertical mold wall surface, while applying a mold powder on top of the molten steel in a casting mold; and withdrawing a formed continuous casting from the vertical continuous casting mold at a predetermined withdrawing velocity V c, wherein:
the vertical continuous casting mold is vertically oscillated at a vertical velocity V m which follows a sine curve relative to time, and a series of actions are simultaneously repeated, the actions being composed of:
(1) separating at least one of the pairs of the mold wall surfaces horizontally from the solidified shell at a distance of no more than 1 mm so that the mold powder flows in a gap between the mold wall surface and the solidified shell during any period of time, and (2) subsequently making the separated mold wall surfaces close to the solidified shell during another period of time, in each of:
(a) a positive strip time zone and a negative strip time zone when there is a negative time zone that is a time zone in which the vertical velocity V m of the mold is smaller than the withdrawing velocity V c of the casting; or (b) a mold ascending period and a mold descending period when there is no negative time zone.
casting the molten steel into a casting space of a vertical continuous casting mold having two pairs of vertical mold wall surfaces, thereby forming a solidified shell of the steel on each vertical mold wall surface, while applying a mold powder on top of the molten steel in a casting mold; and withdrawing a formed continuous casting from the vertical continuous casting mold at a predetermined withdrawing velocity V c, wherein:
the vertical continuous casting mold is vertically oscillated at a vertical velocity V m which follows a sine curve relative to time, and a series of actions are simultaneously repeated, the actions being composed of:
(1) separating at least one of the pairs of the mold wall surfaces horizontally from the solidified shell at a distance of no more than 1 mm so that the mold powder flows in a gap between the mold wall surface and the solidified shell during any period of time, and (2) subsequently making the separated mold wall surfaces close to the solidified shell during another period of time, in each of:
(a) a positive strip time zone and a negative strip time zone when there is a negative time zone that is a time zone in which the vertical velocity V m of the mold is smaller than the withdrawing velocity V c of the casting; or (b) a mold ascending period and a mold descending period when there is no negative time zone.
4. The process of claim 3, wherein only one pair of the mold wall surfaces are separated horizontally from the solidified shell.
5. The process of claim 4, wherein the vertical continuous casting mold has a pair of short sides and a pair of long sides; and only the pair of long sides are horizontally separated from the solidified shell.
6. The process of any one of claims 3 to 5, wherein the molten steel is stainless steel.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP1992/001205 WO1994006583A1 (en) | 1992-09-22 | 1992-09-22 | Method of casting continuous slab |
| CA002098572A CA2098572C (en) | 1992-09-22 | 1992-09-22 | Casting process for continuous castings |
| EP92920028A EP0618023B1 (en) | 1992-09-22 | 1992-09-22 | casting continuous slab in oscillated mold with horizontally retractable walls |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP1992/001205 WO1994006583A1 (en) | 1992-09-22 | 1992-09-22 | Method of casting continuous slab |
| CA002098572A CA2098572C (en) | 1992-09-22 | 1992-09-22 | Casting process for continuous castings |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2098572A1 CA2098572A1 (en) | 1994-03-23 |
| CA2098572C true CA2098572C (en) | 1999-12-21 |
Family
ID=25676288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002098572A Expired - Fee Related CA2098572C (en) | 1992-09-22 | 1992-09-22 | Casting process for continuous castings |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2098572C (en) |
| WO (1) | WO1994006583A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6171863B2 (en) * | 2013-11-08 | 2017-08-02 | 新日鐵住金株式会社 | Continuous casting mold and continuous casting method using the same |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6418553A (en) * | 1987-07-13 | 1989-01-23 | Kawasaki Steel Co | Instrument for detecting friction force between mold and cast slab in continuous casting apparatus |
| US4945975A (en) * | 1988-12-08 | 1990-08-07 | Kawasaki Steel Corporation | Method of oscillation of mold of vertical continuous caster |
| JP2589382B2 (en) * | 1989-09-11 | 1997-03-12 | 川崎製鉄株式会社 | Mold vibrating equipment in continuous casting equipment |
| JPH03297546A (en) * | 1990-04-16 | 1991-12-27 | Kawasaki Steel Corp | Method for oscillating mold for vertical type continuous casting |
| JPH04143057A (en) * | 1990-10-02 | 1992-05-18 | Kawasaki Steel Corp | Method for oscillating mold for vertical type continuous casting |
-
1992
- 1992-09-22 CA CA002098572A patent/CA2098572C/en not_active Expired - Fee Related
- 1992-09-22 WO PCT/JP1992/001205 patent/WO1994006583A1/en active IP Right Grant
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994006583A1 (en) | 1994-03-31 |
| CA2098572A1 (en) | 1994-03-23 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |