Claims:1. An inverse continuous casting simulation system (100) comprising:
a gantry (104) with a movable frame (108);
a melting furnace (112) to provide a molten metal, the melting furnace (112) being positioned below the gantry (104);
a mold (120) being covered by a cover (124), uncovering a portion of the mold (120), the mold (120) being movable with respect to the cover (124), the mold (120) and the cover (124) being configured to be immersed in the molten metal for casting over the mold (120), the mold (120) being oscillated in the molten metal; and
a predetermined meniscus level (126) of the molten metal is being maintained when the cover (124) is lowered in the molten metal by a simultaneous rise of the mold (120) and the cover (124) together.

2. The system (100) as claimed in claim 1, wherein melting furnace (112) is an IF or resistance heating melting furnace (112).

3. The system (100) as claimed in claim 1, wherein the mold (120) comprises one or more of thermocouple (128) to capture temperature data of the mold (120) during continuous casting simulation.

4. The system (100) as claimed in claim 1, wherein mold powder, casting speed, oscillation stroke, oscillation frequency is predefined.

5. The system (100) as claimed in claim 1, wherein casting behaviour is evaluated post continuous casting simulation.

6. The system (100) as claimed in claim 1, wherein the mold (120) and the cover (124) is vertically positioned inside the melting furnace (112) by means of a frame vertical motion mechanism (FVMM) (132), the FVMM (132) being communicatively coupled to the movable frame (108), the movable frame (108) being coupled to the mold (120) and the cover (124).

7. The system (100) as claimed in claim 6, wherein the FVMM (132) comprises a first and second motor (M1, M2) positioned on the gantry (104).

8. The system (100) as claimed in claim 1, wherein the cover (124) is separated from the mold (120) creating further uncovering of the portion over the mold (120) by means of an un-covering mechanism (UCM) (140), the UCM (140) being coupled with the cover (120) and is being configured to pull the cover (124) down in the molten metal.

9. The system (100) as claimed in claims 6 & 8, wherein the predetermined meniscus level (126) of the molten metal is maintained when the cover (124) is lowered in the molten metal by the UCM (140), the FVMM (132) raises the mold (120) and the cover (124) via the movable frame (108) equidistantly, thereby maintaining a casting speed.

10. The system (100) as claimed in claim 9, wherein a sync is established between the UCM (140) and the FVMM (132), when the cover (124) is pulled down in the molten metal.

11. The system (100) as claimed in claim 8, wherein the un-covering mechanism (UCM) (140) comprises a third motor (M3) positioned over the gantry (104).

12. The system (100) as claimed in claim 1, wherein residence time for casting is 5 to 10 sec.

13. The system (100) as claimed in claim 1, wherein the mold (120) and the cover (124) is manoeuvred horizontally over the gantry (104) by means of a horizontal motion mechanism (HMM) (144) communicatively coupled to the mold (120) and the cover (124).

14. The system (100) as claimed in claim 13, wherein the HMM (144) comprises a fourth motor (M4).

15. The simulator (100) as claimed in claim 1, wherein the mold (120) is oscillated by an oscillated motion mechanism (OMM) (148), the OMM (148) being communicatively coupled to the mold (120).

16. The simulator (100) as claimed in claim 15, wherein the oscillated motion mechanism (OMM) (148) comprises a fifth motor (M5) positioned over the gantry (104).

17. The system (100) as claimed in claim 1, wherein molten metal is steel.

18. The system (100) as claimed in claim 1, wherein the cover (124) is made up of mild steel.

19. The system (100) as claimed in claim 1, wherein the mold (120) is made of copper.

20. The system (100) as claimed in claim 1, wherein mold (120) has a cooling channels (156).

21. The system (100) as claimed in claims 7, 11, 14 and 16, wherein the first, second third fourth and fifth motors are stepper based, servo based, or hydraulic based or electrical based.

22. A method of inverse casting, the method comprising:
positioning a cover (124) over a mold (120) leaving an uncovered portion over the mold (120);
positioning the mold (120) and the cover (124) in a molten metal of a melting furnace (112) maintaining a predetermined meniscus level (126);
oscillating the mold (120) in the molten metal;
pulling down the cover (124) in the molten metal and simultaneously raising the mold (120) and the cover (124) together to maintain the meniscus level (126).

23. The method as claimed in claim 22, wherein the cover (124) and the mold (120) is horizontally manoeuvred over a gantry (104) to be positioned over the melting furnace (112).

24. The method as claimed in claim 22, wherein the mold (120) comprises one or more thermocouples (128) to capture temperature data of the mold (120) during continuous casting simulation.

25. The method as claimed in claim 24, wherein the temperature data of the mold (120) is fed into a computer processing system in real time.

26. The method as claimed in claim 25, wherein the temperature data is accepted and analysed for real time monitoring and profiling the thermal history of the mold.
, Description:TECHNICAL FIELD: The present invention relates to a metallurgy. More particularly the present invention relates to a metal continuous casting simulation.
BACKGROUND OF THE INVENTION
The continuous casting process requires suitable mould powder to be fed along with the liquid steel to ensure smooth casting. Improper mould powder selection and addition results in initiation of cracks in the solidified shell, caster damages, process interruptions etc. The prime role of mould powder in continuous casting process is to efficiently control the heat transfer so as to protect the solidifying shell from cracking.
At present several plant trials are needed to obtain an understanding on the behaviour of mould powder, however, these plant trials not only incur significant operational costs but also associated with a great risk of caster damages (break out, mould wear and stoppages). Moreover, it has been noticed that a chosen mould powder behaves differently even within its known working composition range.
There may be many other plant trials needed for trying out casting at different casting speed, different oscillation stroke, different oscillation frequency etc. which is not possible with running caster in the plant. There is a lot of risk involved in trying out various other parameters apart from the conventionally set from OEMs as they are quite costly and in case caster gets damage, returning back to normalcy will take a lot of time with added cost and loss of production.
OBJECTIVE OF INVENTIONS
An object of the invention is to develop a continuous casting simulation system for various metals where key properties of the casting can be varied and evaluate the casting performance.
Another object of the invention is to develop a method for inverse casting for various metals where key properties of the casting can be varied and evaluate the casting performance.
DISCLOSURE OF THE INVENTION
The present invention provides an inverse continuous casting simulation system comprising:
a gantry with a movable frame;
a melting furnace to provide a molten metal, the melting furnace being positioned below the gantry;
a mold being covered by a cover, uncovering a portion of the mold, the mold being movable with respect to the cover, the mold and the cover being configured to be immersed in the molten metal for casting over the mold, the mold being oscillated in the molten metal; and
a predetermined meniscus level of the molten metal is being maintained when the cover is lowered in the molten metal by a simultaneous rise of the mold and the cover together.
The provision of the mold, the cover, the molten metal and the oscillation of the mold simulates the continuous casting. When the cover is immersed in the molten metal, the predetermined meniscus level tends to rise, which is being compensated by the simultaneous rise of the cover and the mold together.
In an embodiment, the melting furnace is an IF or resistance heating melting furnace.
In another embodiment, the mold comprises one or more of thermocouple to capture temperature data of the mold during continuous casting simulation.
In another embodiment, mold powder, casting speed, oscillation stroke, oscillation frequency is predefined and casting behaviour is evaluated post continuous casting simulation.
In another embodiment, the mold and the cover is vertically positioned inside the melting furnace by means of a frame vertical motion mechanism (FVMM), the FVMM being communicatively coupled to the movable frame, the movable frame being coupled to the mold and the cover.
In yet another embodiment, the FVMM comprises a first and second motor positioned on the gantry.
In yet another embodiment, the cover is separated from the mold creating further uncovering of the portion over the mold by means of an un-covering mechanism (UCM), the UCM being coupled with the cover and is being configured to pull the cover down in the molten metal.
In another embodiment, the predetermined meniscus level of the molten metal is maintained when the cover is lowered in the molten metal by the UCM, the FVMM raises the mold and cover via the movable frame equidistantly, thereby maintaining a casting speed.
In another embodiment, a sync is established between the UCM and the FVMM, when the cover is pulled down in the molten metal.
In another embodiment, the un-covering mechanism (UCM) comprises a third motor positioned over the gantry.
In still another embodiment residence time for casting is 5 to 10 sec.
In still another embodiment, the mold and the cover is manoeuvred horizontally over the gantry by means of a horizontal motion mechanism (HMM) communicatively coupled to the mold and the cover.
In yet another embodiment, the horizontal motion mechanism (HMM) comprises a fourth motor.
In yet another embodiment, the mold is oscillated by an oscillated motion mechanism (OMM), the OMM being communicatively coupled to the mold.
In yet another embodiment, the oscillated motion mechanism (OMM) comprises a fifth motor positioned over the gantry.
In yet another embodiment, molten metal is steel.
In yet another embodiment the cover is made up of mild steel.
In yet another embodiment, the mold made of copper.
In yet another embodiment, the mold has a cooling channels.
In yet another embodiment, the first, second third fourth and fifth motors are stepper based, servo based, or hydraulic based or electrical based.
The present invention also provides a method of inverse casting, the method comprising:
positioning a cover over a mold leaving an uncovered portion over the mold;
positioning the mold and the cover in a molten metal of a melting furnace maintaining a predetermined meniscus level;
oscillating the mold in the molten metal;
pulling down the cover in the molten metal and simultaneously raising the mold and the cover together to maintain the meniscus level.
In an embodiment, the cover and the mold is horizontally manoeuvred over a gantry to be positioned over the melting furnace.
In another embodiment, the mold comprises one or more thermocouples to capture temperature data of the mold during continuous casting simulation.
In still another embodiment, the temperature of the mold is fed into a computer processing system in real time.
In yet another embodiment, the temperature data is accepted and analysed for real time monitoring and profiling the thermal history of the mold.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of an inverse continuous casting simulation system in accordance with an embodiment of the invention.
FIG. 2 is a sectional view of a mold and a cover along with a plurality of thermocouples positioned over the mold of the simulation system of Fig. 1.
FIG. 3 is an explanatory view of the system of FIG. 1.
FIG. 4 shows various mechanisms and control arrangement of the mold and the cover of FIG. 1.
FIG. 5 shows a method of inverse casting in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFEREED EMBODIMENTS
In accordance with an embodiment of the invention an inverse continuous casting simulation system (hereinafter system (100)) is shown in FIG. 1. The system (100) comprises a gantry (104) with a movable frame (108) movable up and down. The system (100) comprises a melting furnace (112) to provide molten metal, the melting furnace (112) is positioned below the gantry (104).
The gantry (104) comprises a plurality of guide rods (116) via which a mold (120) and a cover (124) is maneuvered.
Shown in FIGS. 1, 2 and 3, the mold (120) and the cover (124) are configured to be immersed in the molten metal for casting to simulate the casting over the mold (120). The mold (120) oscillates in the molten metal.
Shown in FIG. 2, the mold (120) being covered by the cover (124) with small uncovering portion (125) left on the mold. This uncovered face is configured to initiate the casting. The mold (120) is movable with respect to the cover (124) i.e. the cover can be moved downwards with respect to the mold providing more face on the mold to provide further casting post initiating. The mold (120) and the cover (124) are independent of each other in respect of their movement.
The cover (120) uncovers the working face of the mold independently during operation and is detachable.
The mold (120), the cover (124) and the molten metal and others together simulates the mold with molten metal of a continuous caster in an industrial operation.
To simulate the casting in the caster, a predetermined meniscus level (126) of the molten metal needs to be maintained as shown in FIG. 3. To simulate the continuous casting, the cover (124) is pulled down in the molten metal due to which molten metal level tend to rise. This tend to raise the meniscus level (126) as well, which can be compensated or negated by simultaneously raising the mold and the cover equidistantly above the molten metal, thereby maintaining a casting speed. The pulling down of the cover is done by an uncovering mechanism (UCM) (explained later). The raising of the mold and the cover equidistantly is done by a movable frame (explained later), which is guided by a frame vertical motion mechanism FVMM (explained later). The uncovering of the cover during operation simulates the role of “dummy bar” while initiation of the continuous casting process in the industry.
Various stages (Stage 1-4) of rising of the mold (120) and the cover (124) as the cover (124) is lowered in the furnace is shown in FIG. 3. The initial melt level is shown to be set at meniscus level (126), Stage 1. Once the meniscus level rises, due to the lowering of the cover inside the furnace, the mold and cover further risen up, stage 2, to maintain the same meniscus level. Further rise in the mold and cover is shown as the cover is further pulled down, stage 3 and 4, maintaining the same meniscus level as set initial. In the end, casting is performed over the mold leading the full-grown cast over the mold replicating the industrial caster.
In an embodiment, the rise in the meniscus level can be compensated by the raising the furnace (112) as well, but the furnace (112) being heavy therefore not feasible.
The melting furnace (112) in an embodiment is an IF or resistance heating melting furnace. Again, shown in FIG. 1 is a platform (127) over which the furnace is positioned. Also, various necessary struts and trusses are deployed to support the gantry.
The mold (120) comprises one or more of thermocouple (128) to capture temperature data of the mold (120) during continuous casting simulation.
In the system (100) mold powder, casting speed, oscillation stroke, oscillation frequency is predefined.
The casting rate behaviour is evaluated post continuous casting simulation.
Shown in FIGS. 1 and 3 is the mold (120) and the cover (124) being vertically positioned inside the melting furnace (112) by means of a movable frame (108). The movement of the movable frame is being controlled by a frame vertical movement mechanism (FVMM) (132) shown in FIG. 4. The FVMM (132) is communicatively coupled to the movable frame (108) which is further coupled and thereby effects the motion of the mold (120) and the cover (124). The FVMM (132) comprises of a first motor and a second motor (M1 & M2), both being positioned on the gantry (104). The movable frame (108) can be lifted and lowered with respect to the gantry (104). This lowering and raising of the movable frame (108) lowers and raises the mold (120) and the cover (124) as well.
The first and the second motors (M1 & M2) operate in bi-directional mode via toggle switch. The motors (M1 & M2) are configured to make shift the mold with cover from top position to bottom position and vice versa with a determined operating height.
The motors act as set point height for operation.
Shown in FIGS. 3 and 4, the lowering of the cover (124) in the molten metal is executed by an un-covering mechanism (UCM) (140) coupled with the cover (124). The un-covering mechanism (UCM) (140) is comprised of a third motor (M3) positioned over the gantry (104). Till the time the cover is not lowered down in the molten metal, there is no change in the meniscus level (126). Till then, the UCM (140) and the FVMM (132) are independent with each other’s movement. But as the cover (124) is lowered further in the molten metal, the sync is established between the two and they start working in close loop. And simultaneously for the appropriate height of the cover and mold is raised maintaining the predetermined speed of uncovering. The appropriate speed of uncovering is necessary as it gives appropriate time for casting. The uncovering speed is predetermined and simulate the casting speed as per the industry caster.
The FVMM (132) also involves the integration of electrical drives for auto lifting of the mold (120) and cover (124) after immersion into the molten metal and pre-defined holding time when the simulation ends. The sync of the FVMM (132) and the UCM (140) is microcontroller and logical program based mechanism for any predefined set of operating parameters for a defined dip height of the mold in the molten metal. The limitation of the process parameters and automation mechanism depends on the size/capacity of the melting furnace. Based on the furnace mouth diameter the following equation is incorporated in the logical program:
VR = VS x 0.256
Where, VR = Velocity of liquid metal raise due to volume displacement Vs = Velocity of cover uncovering or casting speed
When the mold (120) and the cover (124) is lowered in the molten metal, the predetermined meniscus level is maintained and a predetermined residence time is allotted so as to initiate the casting over uncovered surface of the mold. The residence time in an embodiment can be 5-10 seconds.
Preferably, the un-covering is done in auto mode. But in another embodiments, it can be done manually as well. The lowering of the mold and the cover prior to sync can be done in auto or manual mode.
Before lowering the mould (120) and the cover (124) in the furnace (112), they are manoeuvred horizontally over the gantry (104) by means of a horizontal motion mechanism (HMM) (144) communicatively coupled to the mold (120) and the cover (124) as shown in FIGs 1 & 4. The horizontal motion mechanism (HMM) (144) comprises a fourth motor (M4) for its motion.
The fourth motor (M4) is positioned over the gantry (104) and operates in bi-directional mode via toggle switch. Purpose of M4 is to make shift the mold (120) along with the cover (124) in horizontal position with the pre-set frequency.
For HMM, a pre-set position is selected based on test conditions. This motor (M4) can be operated both in auto & off-line mode. This motor is configured to align the mold (120) and the cover (124) above the mouth of the furnace (112) where the experiments/simulation need to be conducted.
In an embodiment, the horizontal manoeuvring of the mold and the cover can be done manually as well.
To simulate the mold of the caster and allow the molten metal to cast, the mold (120) is being oscillated in the molten metal. This oscillation is performed by an oscillated motion mechanism (OMM) (148) communicatively coupled to the mold (120) as shown in FIG. 4. The OMM (148) comprises a fifth motor (M5) positioned over the gantry (104).
The mold independently oscillates via the OMM within the cover and is detachable in nature with proper joints. Similarly, the mold and the cover is manoeuvred horizontally via HMM independently.
The oscillation frequency of the mold can be varied in a range of 1-5 Hz as per the simulation requirement. A display (152) is provided in the OMM where the frequency can be entered. Motor (M5) is the critical bi-directional motor in-built with VVVF driven system for accurate speed and frequency control. Based on the operational speed and frequency of vertical moment, real time simulation procedure for continuous casting can be attained.
In an embodiment, the bi-directional motor (M5) is selected for carrying the mold weight up to 30kg and for the vertical moment of ±10mm (stroke length) from set position. Starting and running torque were selected based on 40kg net weight. Frequency ranging from 1-6 Hz can be selected from the control unit based on the simulation and operational requirement.
At the end of simulation, the cover (124) can be separated off the mold (120) by the UCM (140) creating further access of uncovered portion over the mold. The M3 of the UCM (140) is communicatively coupled with a special type pinion arrangement connecting to the cover (124). Based on the speed of M4, extraction (uncovering/casting) speed ranging from 1 to 15mm/sec can be selected based on the simulation requirement.
In accordance with an embodiment of the invention the molten metal is liquid steel, molten aluminium, molten lead, molten wax etc.
In accordance with an embodiment of the invention the cover (124) is made up of mild steel.
In accordance with an embodiment of the invention the mold (120) is made of copper. The copper includes electrical grade copper with high purity. The heat extraction in the mold occurs unidirectional due to water cooling allows the growth of the initial steel shell which akin to the industrial continuous casting process throughout the simulation process.
In an embodiment, the cover (124) is detachable along with the system such that the copper mold can be separated and re-used for another simulation experiment.
In accordance with an embodiment of the invention the melting furnace (112) is 20 kg air induction melting furnace.
In accordance with an embodiment of the invention the mold (120) comprises a cooling channels (156) shown in FIG. 2. In an embodiment, the mold (120) is water cooled and designed and fabricated for housing the water cooling channels to provide cooling to extract the heat continuously.
The first, second, third, fourth and fifth motors can be stepper based, servo based, or hydraulic based or electrical based.
Section view of the mold (120) is shown in FIG. 2 along with 3D view. B-type thermocouples are coupled with a computer processing system (not shown) where the temperature data is accepted and analysed for real time monitoring of temperature data. This real-time temperature data is used for profiling the thermal history of the mold. The thermal history of the mold can be continuously monitored during continuous casting simulation process and recorded for further analysis and characterization pertaining to assessment such as of mold powders for castability, casting speed, oscillation stroke, oscillation frequency, casting rate.
In an embodiment, the thermal history of the water-cooled copper mould is measured and recorded in milli seconds for further analysis. In another embodiment set of 14 nos of B type thermocouple is fixed in to the mold as per the TC arrangement.
Shown in FIG. 5 is in accordance with an embodiment of the invention is a method (500) of inverse casting. The method comprises
Step 504, where positioning a cover (124) over a mold (120) leaving an uncovered portion over the mold (120).
At 508, the mold (120) and the cover (124) in a molten metal of a melting furnace (112) is positioned maintaining a predetermined meniscus level (126).
At 512, the mold (120) in the molten metal is oscillated.
At 516, the cover (124) in the molten metal is pulled down and simultaneously the mold (120) and the cover (124) together is raised up to maintain the meniscus level (126).
In an embodiment, the cover (124) and the mold (120) is horizontally manoeuvred over a gantry (104) to be positioned over the furnace (112).
In an embodiment, the mold (120) comprises a one or more thermocouples (128) to capture temperature data of the mold (120) during continuous casting simulation. The temperature data of the mold is fed into a computer processing system in real time. The temperature data is accepted and analysed for real time monitoring and profiling the thermal history of the mold.
The system is aimed for simulation of initial solidification process (mould phenomena) that occur during continuous casting of liquid steel in the atmosphere similar to the industrial continuous casting process. Accordingly, in an embodiment, the present disclosure provides:
a) Simulation of continuous casting process under variable process parameters such as casting speed, oscillation stroke, oscillation frequency and cooling rate for a particular combination of liquid steel and mould powders.
b) The mould is designed such that the cooling and casting simulation will be subjected to one face of the water-cooled copper mould and rest three faces are covered by the steel cover. Hence, the initial steel shell grows unidirectional due to continuous heat extraction by water cooling akin to the industrial continuous casting process.
c) The half covered portion of steel cover is uncovered in a defined (casting) speed to allow the fresh steel shell to grow perpendicular to the mould face, while the fresh cast steel shell is pulled down due to uncovering of steel shield to simulate the continuous casting process.
d) The casting parameters (casting speed, oscillation stroke, oscillation frequency and cooling rate) can be varied independently to study the performance of mould powder for particular grade of liquid steel and mould powders.
e) Measure and record the thermal history of water cooled mould using 16 number of thermocouples during on-line operation.
f) The continuous casting of liquid steel along with infiltration of molten mould flux in between the newly cast steel shell and water-cooled copper mould to control the heat transfer during operation.

Advantages:
The advantages of the present invention are:
The system (100) is movable from location to another.
The system (100) enables simulation and monitoring of the continuous casting process to study the castability of different liquid steels with different mold powders.
The system (100) comprises components enabling to simulate the industrial continuous casting process varying the process parameters such as casting speed, oscillation stroke, oscillation frequency, composition of liquid steel and mold powders.
The system is useful for 1) simulation of continuous casting process mold phenomena, 2) evaluation of the mold powders performance in a specified combination of process parameters, and 3) development of new mold powders for crack sensitive steel grades.
The system (100) allows the oscillation stroke, oscillation frequency, casting speed and cooling rate can be controlled independently to perform various simulation experiments.
The system (100) allows to simulate the initial solidification phenomena occurs in primary cooling zone during continuous casting process of liquid steel.
The system (100) allows to generate initial solidified cast structure akin to the solidified structure generated in industry with oscillation marks.
The system (100) allows to control and maintain the casting speed during the simulation process within a range of 1 to 15mm/s.
The system (100) allows to control and maintain the oscillation stroke during the simulation process within a range of 1 to 10mm.
The system (100) allows to control and maintain the oscillation frequency during the simulation process within a range of 1 to 6Hz.
The system (100) allows to perform the continuous casting simulation experiments in varies molten metals and liquids e.g. liquid steel, molten aluminum, molten lead, molten wax etc.
References:
System 100
Gantry 104
Movable frame 108
Melting furnace 112
Guide rods 116
Mold 120
Cover 124
Uncovered face 125
Meniscus level 126
Thermocouple 128
Platform 127
FVMM 132
UCM 140
HMM 144
OMM 148
Display 152
Cooling channels 156