CN114854994B - Device and method for preparing composite steel ingot based on conductive crystallizer - Google Patents
Device and method for preparing composite steel ingot based on conductive crystallizer Download PDFInfo
- Publication number
- CN114854994B CN114854994B CN202210253313.2A CN202210253313A CN114854994B CN 114854994 B CN114854994 B CN 114854994B CN 202210253313 A CN202210253313 A CN 202210253313A CN 114854994 B CN114854994 B CN 114854994B
- Authority
- CN
- China
- Prior art keywords
- conductive interface
- crystallizer
- interface
- lower conductive
- upper conductive
- 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.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/06—Permanent moulds for shaped castings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/02—Use of electric or magnetic effects
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
A device and a method for preparing composite steel ingots based on a conductive crystallizer, wherein the device comprises a T-shaped crystallizer; the outer wall of the upper crystallizer of the T-shaped crystallizer is provided with an extension part, the outer wall of the extension part is provided with a conductive interface, and the lower part of the outer wall of the upper crystallizer is provided with a lower conductive interface; the method comprises the following steps: (1) placing the mandrel into a T-type crystallizer; (2) arranging a coating layer in the T-shaped crystallizer; (3) pouring molten slag into a liquid slag pool; the power supply and the conductive interface are connected according to different combinations; (4) lowering the consumable electrode to the liquid slag bath; the switch is closed, and the consumable electrode is heated and melted; (5) Under the cooling action, the metal molten pool is cooled to form a cladding layer to wrap the mandrel; starting the ingot drawing system. According to the device and the method, the influence of the magnetic field on the flow of slag in the crystallizer is regulated by changing the current distribution of the upper crystallizer, so that the uniformity of the temperature field of the slag pool and the metal molten pool is improved, the circumferential uniformity of the interface bonding quality of the composite roller is further improved, the product quality is improved, and the service life of the roller is effectively prolonged.
Description
Technical Field
The invention belongs to the technical field of metallurgical equipment, and particularly relates to a device and a method for preparing a composite steel ingot based on a conductive crystallizer.
Background
With the rapid promotion of economic construction and industrialization progress and with the expansion of productivity of iron and steel enterprises, newly built production rolling mills are continuously increased, so that the 'blowout' strong demand is brought to the roller manufacturing industry, and meanwhile, the quality and performance of the rollers directly influence the production efficiency of the rolling mill, the surface quality of rolled materials and the rolling cost. Therefore, how to manufacture the composite roller with the mechanical strength, toughness and wear resistance meeting the requirements is a common concern in the metallurgical industry.
The existing preparation methods of the composite roller mainly comprise a centrifugal casting method, a continuous casting method and an electroslag liquid casting method; the working layer of the composite roller prepared by the centrifugal casting method has serious carbide segregation under the action of centrifugal force.
The core equipment conductive crystallizer for preparing the composite roller by the electroslag remelting method is a novel crystallizer, and a plurality of scholars are focused on the function and application development of the conductive crystallizer at present; physical and numerical simulation of single-power double-loop conductive crystallizer electroslag remelting nickel-based alloy (academic paper, university of northeast, 2015), numerical simulation of T-type conductive crystallizer electroslag remelting hollow steel ingot process (university of northeast, 2015), and a method for preparing H13 steel by conductive crystallizer electroslag remelting (publication No. CN106435209A, [ P ]. 2006.01) mainly prepare large-sized high-alloy low-segregation steel ingots by optimizing power supply loops and adjusting the magnitude of current; and the structure of the conductive crystallizer is less deeply developed and designed.
Because the short net current of the traditional electroslag remelting furnace has a non-uniform electromagnetic stirring effect on a molten pool, the circumferential non-uniformity of the ingot quality is caused, and the influence of the short net on the flow of the molten pool is eliminated by arranging the short net and the electroslag remelting furnace into a coaxial conductive structure, so that the circumferential uniformity of the ingot quality is improved. The current of the conductive crystallizer is closer to the metal molten pool, and the tangential current value of the conductive crystallizer is larger, so that the current of the conductive crystallizer can generate a strong electromagnetic stirring effect in the metal molten pool, and the non-uniform electromagnetic stirring effect can cause non-uniformity of an electromagnetic field, a flow field and a temperature field, thereby affecting the interface bonding quality of an ingot casting or a composite roller.
Disclosure of Invention
In order to solve the problem of influence of non-uniformity of an electromagnetic field, a flow field and a temperature field in a traditional electroslag remelting furnace crystallizer on product quality, the invention aims to provide a device and a method for preparing a composite steel ingot based on a conductive crystallizer.
The device for preparing the composite steel ingot based on the conductive crystallizer comprises a T-shaped crystallizer, a dummy ingot plate 16 and a power supply 1; the T-shaped crystallizer consists of an upper crystallizer and a lower crystallizer 10; the upper part of the outer wall of the upper crystallizer is provided with an upper crystallizer lengthening part 6, the outer wall of the crystallizer lengthening part 6 is provided with an upper conductive interface 5, and the lower part of the outer wall of the upper crystallizer is provided with a lower conductive interface 8.
In the device, the upper crystallizer consists of a first part 14-1, a second part 14-2, a third part 14-3 and a fourth part 14-4 which are identical in shape and size, wherein the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are arc-shaped plates; the upper crystallizer is internally provided with a cylindrical graphite ring 18, and the outer wall surface of the graphite ring 18 is simultaneously connected with the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4; the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are arranged around the graphite ring 18, and two adjacent parts are connected with one plate-shaped insulating gasket 7 together, and a total of four insulating gaskets 7 are respectively a first insulating gasket 7-1, a second insulating gasket 7-2, a third insulating gasket 7-3 and a fourth insulating gasket 7-4; the upper parts of the outer walls of the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are respectively provided with an arc-shaped platy crystallizer lengthening part 6, and four crystallizer lengthening parts 6 of the upper crystallizer are respectively a first lengthening part 6-1, a second lengthening part 6-2, a third lengthening part 6-3 and a fourth lengthening part 6-4; a gap is reserved between two adjacent crystallizer lengthening parts; the lower parts of the outer walls of the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are respectively provided with two lower conductive interfaces 8, and the two lower conductive interfaces 8 of each part are respectively positioned at two ends of each part, namely a first lower conductive interface 8-1, a second lower conductive interface 8-2, a third lower conductive interface 8-3, a fourth lower conductive interface 8-4, a fifth lower conductive interface 8-5, a sixth lower conductive interface 8-6, a seventh lower conductive interface 8-7 and an eighth lower conductive interface 8-8; each crystallizer lengthening part 6 is respectively provided with two upper conductive interfaces 5, namely a first upper conductive interface 5-1, a second upper conductive interface 5-2, a third upper conductive interface 5-3, a fourth upper conductive interface 5-4, a fifth upper conductive interface 5-5, a sixth upper conductive interface 5-6, a seventh upper conductive interface 5-7 and an eighth upper conductive interface 5-8; the two upper conductive interfaces 5 on each mould extension 6 are located at the two ends of each mould extension 6.
In the above apparatus, the mold extensions of the first, second, third and fourth sections 14-1, 14-2, 14-3 and 14-4 are integrally formed with the first, second, third and fourth sections 14-1, 14-2, 14-3 and 14-4, respectively.
In the above device, a liquid level detecting probe 11 is installed on the lower crystallizer 10, and the liquid level detecting probe 11 is assembled on a liquid level detector.
In the device, a circular ring-shaped insulating gasket 9 is arranged between the upper crystallizer and the lower crystallizer 10.
In the device, one pole of the power supply 1 is connected with the upper conductive interface 5 and/or the lower conductive interface 8 through a short network, and the other pole is connected with the consumable electrode 2; the short net is provided with a switch 17.
In the device, the lower crystallizer 10 is provided with two liquid level detection probes 11, and the two liquid level detection probes 11 are assembled on the same liquid level detector together; the height difference of the two liquid level detection probes 11 is 15-20 mm; the projections of the axes of the two liquid level detection probes 11 on the horizontal plane form an included angle theta or are overlapped; the included angle θ=90, 180, or 270.
The method for preparing the composite steel ingot based on the conductive crystallizer adopts the device and comprises the following steps:
(1) The mandrel 3 is arranged in a T-shaped crystallizer, and the bottom surface of the mandrel 3 is connected with a dummy ingot plate 16; the dummy ingot plate 16 is connected with the bottom surface of the lower crystallizer lower part 14;
(2) A coating layer 15 is arranged in the T-shaped crystallizer, and the space between the mandrel 3 and the lower crystallizer 10 is filled with the coating layer 15;
(3) Pouring the melted slag into a T-shaped crystallizer to form a liquid slag pool 4; one pole of the power supply 1 is connected with the upper conductive interface 5 and/or the lower conductive interface 8 through a short network, and the other pole is connected with the consumable electrode 2;
(4) Lowering the consumable electrode 2 into the liquid slag bath 4 by a lifting device; closing the switch 17, and conducting the circuits of the consumable electrode 2, the liquid slag pool 4, the graphite ring 18 and the upper crystallizer; under the action of current, the temperature of the liquid slag pool 4 is gradually increased, the consumable electrode 2 is heated and melted, and the surface of the mandrel 3 is heated to form a melting layer; the molten metal drops formed by melting the consumable electrode 2 are deposited at the bottom of the liquid slag bath 4 to form a metal molten pool 12;
(5) Under the cooling action of the T-shaped crystallizer, the metal molten pool 12 is gradually cooled, and a cladding layer 13 is formed to wrap the outer wall of the mandrel 3; at this time, the ingot pulling system is started, the dummy ingot plate 16 is lowered, and the mandrel 3 wrapped with the cladding layer 13 is pulled out in the process of lowering the dummy ingot plate 16, so that a composite steel ingot is formed.
In the step (3), when one pole of the power supply 1 is connected to the conductive interface, the first, second, third, fourth, fifth or sixth combinations are connected; the first combination is that one pole of the power supply 1 is connected to the first upper conductive interface 5-1, the third upper conductive interface 5-3, the fifth upper conductive interface 5-5 and the seventh upper conductive interface 5-7; the second combination is that one pole of the power supply 1 is connected to the first conductive interface 5-1 and the fifth upper conductive interface 5-5, meanwhile, the third upper conductive interface 5-3 and the fourth upper conductive interface 5-4 are connected through a wire, and the seventh upper conductive interface 5-7 and the eighth upper conductive interface 5-8 are connected through a wire; the third combination is that one pole of the power supply 1 is connected to the first upper conductive interface 5-1, meanwhile, the third upper conductive interface 5-3 and the fourth upper conductive interface 5-4 are connected through a wire, the fifth upper conductive interface 5-5 and the sixth upper conductive interface 5-6 are connected through a wire, and the seventh upper conductive interface 5-7 and the eighth upper conductive interface 5-8 are connected through a wire; one pole of the fourth combined electrode is connected to the first lower conductive interface 8-1, the third lower conductive interface 8-3, the fifth lower conductive interface 8-5 and the seventh lower conductive interface 8-7; the fifth combination is that one pole of the power supply 1 is connected to the first lower conductive interface 8-1 and the fifth lower conductive interface 8-5, meanwhile, the third lower conductive interface 8-3 and the fourth lower conductive interface 8-4 are connected through a wire, and the seventh lower conductive interface 8-7 and the eighth lower conductive interface 8-8 are connected through a wire; the sixth combination is that one pole of the power supply 1 is connected to the first lower conductive interface 8-1, the third lower conductive interface 8-3 and the fourth lower conductive interface 8-4 are connected by a wire, the fifth lower conductive interface 8-5 and the sixth lower conductive interface 8-6 are connected by a wire, and the seventh lower conductive interface 8-7 and the eighth lower conductive interface 8-8 are connected by a wire.
In the step (3), when one pole of the power supply 1 is connected to the conductive interface, it is connected to each of the upper conductive interface 5 and the lower conductive interface 8 at the same time, and each of the upper conductive interface 5 and the lower conductive interface 8 is used as a seventh combination.
In the step (3), when one pole of the power source 1 is connected to the conductive interface of the upper crystallizer in the first combination, the second combination, the third combination, the fourth combination, the fifth combination or the sixth combination, or when one pole of the power source 1 is connected to the conductive interface of the upper crystallizer in the first combination+the fourth combination, the second combination+the fifth combination or the third organization+the sixth combination; forming a counter-clockwise/counter-clockwise annular current in the upper crystallizer; at this time, radial current exists in the liquid slag pool 4; the annular current generates tangential rotary electromagnetic force to radial current, so that the rotary flow of the liquid slag bath 4 is enhanced, the disturbance of a stray magnetic field in the T-shaped crystallizer is controlled, and the influence of the stray magnetic field on the liquid slag bath 4 and the metal molten pool 12 is weakened.
In the step (3), the consumable electrode 2 is cylindrical or cylindrical; when the consumable electrode 2 is cylindrical, it is composed of a plurality of cylindrical consumable electrodes, the plurality of cylindrical consumable electrodes are uniformly distributed on the periphery of the mandrel 3, and the distance between each cylindrical consumable electrode and the mandrel 3 is equal.
In the step (3), when one pole of the power supply 1 is simultaneously connected with all the upper conductive interfaces 5 and the lower conductive interfaces 8, as a seventh combination, the annular current in the T-shaped crystallizer is weakened or eliminated, the current in the T-shaped crystallizer is basically and uniformly distributed along the axial direction, the value of the current in the T-shaped crystallizer is uniformly distributed along the circumferential direction, the crystallizer current generates a uniform magnetic field in the liquid slag bath 4, the liquid slag bath 4 and the metal molten pool 12 uniformly flow, and the circumferential uniformity of the combination quality of the composite ingot interface is ensured.
The device and the method change the current distribution of the upper crystallizer by changing the combination of the shape of the guide crystallizer and the conductive interface, thereby adjusting the influence of the magnetic field on the flow of slag of the crystallizer, improving the uneven distribution of heat of a metal molten pool, improving the quality of products and effectively prolonging the service life of a roller (composite steel ingot). According to the invention, through improving the electroslag test device and the current path, the magnetic fields in the liquid slag pool and the metal molten pool are reasonably optimized, and the influence of electromagnetic force on smelting is lightened, so that the steel ingot with uniform quality and excellent mechanical property is prepared.
Drawings
Fig. 1 is a schematic cross-sectional structure of an apparatus for manufacturing a composite steel ingot based on a conductive mold according to an embodiment of the present invention;
FIG. 2 is a top view of the upper crystallizer section of FIG. 1;
in the figure, 1, a power supply, 2, a consumable electrode, 3, a mandrel, 4, a liquid slag bath, 5, an upper conductive interface, 5-1, a first upper conductive interface, 5-2, a second upper conductive interface, 5-3, a third upper conductive interface, 5-4, a fourth upper conductive interface, 5-5, a fifth upper conductive interface, 5-6, a sixth upper conductive interface, 5-7, a seventh upper conductive interface, 5-8, an eighth upper conductive interface, 6, a crystallizer lengthening part, 6-1, a first lengthening part, 6-2, a second lengthening part, 6-3, a third lengthening part, 6-4, a fourth lengthening part, 7, an insulating spacer, 7-1, a first insulating spacer, 7-2, a second insulating spacer, 7-3, a third insulating spacer, 7-4, a fourth insulating gasket, 8, a lower conductive interface, 8-1, a first lower conductive interface, 8-2, a second lower conductive interface, 8-3, a third lower conductive interface, 8-4, a fourth lower conductive interface, 8-5, a fifth lower conductive interface, 8-6, a sixth lower conductive interface, 8-7, a seventh lower conductive interface, 8-8, an eighth lower conductive interface, 9, a circular insulating gasket, 10, a lower crystallizer, 11, a liquid level detection probe, 12, a molten metal pool, 13, a cladding layer, 14-1, a first part, 14-2, a second part, 14-3, a third part, 14-4, a fourth part, 15, a cladding layer, 16, a dummy plate, 17, a switch, 18 and a graphite ring.
Detailed Description
In the embodiment of the invention, the upper crystallizer is divided into four parts, and each part is provided with a conductive interface respectively; when the seventh combination is adopted in the conductive interface connection mode, current is dispersed in four parts to pass through in the electrifying process, so that the current passing through each part is weakened, most of currents in the crystallizer are uniform along the axial direction and the numerical value of the currents is uniform along the circumferential direction, the magnetic field generated by the current of the conductive crystallizer is weakened, the interference of stray magnetic fields is weakened, and the aim of improving the circumferential uniformity of the interface bonding quality can be achieved.
In the embodiment of the invention, one pole of the power supply is simultaneously connected with a plurality of conductive interfaces of the upper crystallizer; if the annular current needs to be weakened, the conductive interface connection mode adopts a first combination and/or a fourth combination, the current flowing out of the power supply uniformly enters the consumable electrode, and flows in the same direction in the upper crystallizer through the liquid slag pool and is divided into four parts, and flows out of the upper crystallizer through part of the electrical interfaces respectively, and is converged in the short network to be concentrated and returned to the power supply; the large current is divided into four parts, the current is obviously reduced, the four parts of current form counter-clockwise circulation flowing in the crystallizer, and the axial magnetic field generated by the circulation is obviously weakened, so that the generated electromagnetic force is reduced, and the stirring effect on a slag pool is weakened; if the circulation formation needs to be further weakened, a graphite ring is arranged on the inner wall of the upper crystallizer, the thickness of the graphite ring is increased, the distance between the upper crystallizer and the liquid slag pool is increased, and according to the Piaor-savart law, the distance between the upper crystallizer and a current source is increased to obviously reduce the induction magnetic field generated in the slag pool and a metal molten pool, so that the axial magnetic field generated by annular current can be further weakened by adjusting the thickness of the graphite ring, and the uneven stirring effect on the liquid slag pool is weakened.
In the embodiment of the invention, if the influence of annular current on the liquid slag pool is required to be increased, the induction magnetic field is enhanced, and the flow of the liquid slag pool and the metal molten pool is enhanced, the conductive interface connection mode adopts the second combination and/or the fifth combination to divide the large current into two parts, and compared with the first combination and/or the fourth combination, the annular current is increased, the generated induction magnetic field is increased, the electromagnetic force born by the liquid slag pool is increased, and the flow in the liquid slag pool is enhanced.
In the embodiment of the invention, compared with the traditional conductive crystallizer for preparing steel ingots, the closer to the liquid slag pool and the metal molten pool area of the crystallizer, the larger the force is, the more uneven the flow of slag and molten steel is, so that the interface bonding quality circumferential uniformity of the produced composite steel ingot is poor; after the T-shaped electric crystallizer is adopted, the influence of a magnetic field on a metal molten pool is weakened or utilized by changing the connection combination mode of the conductive interfaces of the conductive crystallizer, and the circumferential uniformity of the combination quality of a temperature field and the interfaces is improved.
In the embodiment of the present invention, the insulating spacer 7 is made of asbestos.
In the embodiment of the invention, the mandrel 3 is arranged in the T-shaped crystallizer, and the mandrel 3 is erected on the dummy ingot plate 16 and welded and fixed, so that the axes of the mandrel 3 and the T-shaped crystallizer are overlapped.
In the present embodiment, a magnesia and asbestos rope packing seal is employed between the lower crystallizer 10 and the dummy ingot plate 16.
In the embodiment of the invention, slag is firstly placed in a resistance furnace to be baked and then cooled along with the furnace, then slag is melted in a slag melting bag, and after the slag is completely melted to reach a preset temperature, the slag is poured into a T-shaped crystallizer.
In the embodiment of the invention, after molten slag is poured into the T-shaped crystallizer, the liquid level of the liquid slag pool 4 exceeds the upper edge of the upper part of the lower crystallizer by 20mm.
In the embodiment of the invention, cooling water is introduced into the lower crystallizer to forcedly cool the cladding layer 13.
In the embodiment of the invention, the descending speed of the dummy ingot plate 16 is controlled by the ingot pulling system, so that the pulled speed of the mandrel 3 wrapped with the cladding layer 13 is matched with the melting speed of the consumable electrode 2, and the liquid level of the liquid slag pool 4 and the liquid level of the metal molten pool 12 are kept stable; the level of the molten metal bath 12 is monitored by a level detection probe 11.
In the embodiment of the invention, after the mandrel 3 wrapped with the cladding layer 13 reaches the required length, the ingot pulling system is closed, the consumable electrode 2 is lifted to be separated from the liquid slag pool 4, and the mandrel 3 with the cladding layer 13 is cooled to form a composite steel ingot.
In the embodiment of the invention, an annular liquid sealing plate is welded on the mandrel 3, and the outer diameter of the liquid sealing plate is matched with the inner diameter of the lower crystallizer 10; when the mandrel 3 is connected with the dummy ingot plate 16, aluminum oxide powder is filled between the liquid sealing plate and the dummy ingot plate 16, and the aluminum oxide powder is wrapped and fixed by asbestos cloth to form a coating layer 15; when the ingot drawing system is started, the aluminum oxide powder partially flows out under the wrapping of the asbestos cloth, and the rest part plays a role in protecting the mandrel 3.
In the embodiment of the invention, the interface between the liquid slag bath 4 and the metal molten pool 12 is controlled to be positioned between two liquid level detector probes; the change in the position of the liquid surface of the molten metal bath 12 is detected by a liquid level detector, and the melting speed and the withdrawal speed of the consumable electrode are adjusted based on the change.
In the embodiment of the invention, the lengthened part of the crystallizer is arranged, when a power supply is communicated, the electromagnetic force born by the liquid slag pool during smelting is changed by changing the flowing direction of the short-network current, so that the current directly flows straight from the middle upper part of the conductive section of the side wall of the slag pool during the traditional conductive crystallizer, and flows out of the lengthened part of the crystallizer, the current flows from the inner side of the lengthened part of the crystallizer to the outer side, the magnetic field direction of the slag pool is changed, different conductive interface connection combinations are selected as outflow electrodes, and the flow rate of a molten pool is regulated in a grading manner; when the traditional conductive crystallizer is used for preparing steel, the liquid slag pool is subjected to electromagnetic force, and the larger the electromagnetic force is positioned outside the liquid slag pool, the more uneven the liquid slag pool and a metal molten pool are, and the interface bonding quality of a composite cast ingot is poor; the influence of the magnetic field on the liquid slag pool and the metal molten pool is reduced or utilized by controlling the connection combination of the conductive interfaces, so that the circumferential uniformity of the interface bonding quality of the composite steel ingot is improved.
In the embodiment of the invention, the diameter of the mandrel is 300-1000 mm, and the mandrel is made of cast carbon steel or forged carbon steel.
In the embodiment of the invention, the inner diameter of the consumable electrode 2 is 340-1160 mm, and the outer diameter is 380-1360 mm.
In the embodiment of the invention, the consumable electrode is made of Cr5 steel or high-speed steel; the inner diameter of the cladding layer is 300-1000 mm, and the outer diameter is 400-1300 mm.
In the embodiment of the invention, the length of the composite steel ingot is 500-4000 mm;
in the embodiment of the invention, the inner diameter of the upper crystallizer is 470-1680 mm, and the thickness is 40mm; the thickness of the insulating gasket is consistent with that of the upper crystallizer.
In the embodiment of the invention, the inner diameter of the graphite ring is 390-1600 mm, and the thickness is 40mm.
In the embodiment of the invention, each part of the upper crystallizer is internally provided with a cooling water cavity for circulating cooling water.
Example 1
The device for preparing the composite steel ingot based on the conductive crystallizer has a cross-sectional structure shown in fig. 1, a bottom view shown in fig. 2, and comprises a T-shaped crystallizer, a dummy ingot plate 16 and a power supply 1; the T-shaped crystallizer consists of an upper crystallizer and a lower crystallizer 10; an upper crystallizer lengthening part 6 is arranged at the upper part of the outer wall of the upper crystallizer, an upper conductive interface 5 is arranged on the outer wall of the crystallizer lengthening part 6, and a lower conductive interface 8 is arranged at the lower part of the outer wall of the upper crystallizer;
the upper crystallizer consists of a first part 14-1, a second part 14-2, a third part 14-3 and a fourth part 14-4 which are identical in shape and size, wherein the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are arc-shaped plates; the upper crystallizer is internally provided with a cylindrical graphite ring 18, and the outer wall surface of the graphite ring 18 is simultaneously connected with the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4; the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are arranged around the graphite ring 18, and two adjacent parts are connected with one plate-shaped insulating gasket 7 together, and a total of four insulating gaskets 7 are respectively a first insulating gasket 7-1, a second insulating gasket 7-2, a third insulating gasket 7-3 and a fourth insulating gasket 7-4; the upper parts of the outer walls of the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are respectively provided with an arc-shaped platy crystallizer lengthening part 6, and four crystallizer lengthening parts 6 of the upper crystallizer are respectively a first lengthening part 6-1, a second lengthening part 6-2, a third lengthening part 6-3 and a fourth lengthening part 6-4; a gap is reserved between two adjacent crystallizer lengthening parts; the lower parts of the outer walls of the first part 14-1, the second part 14-2, the third part 14-3 and the fourth part 14-4 are respectively provided with two lower conductive interfaces 8, and the two lower conductive interfaces 8 of each part are respectively positioned at two ends of each part, namely a first lower conductive interface 8-1, a second lower conductive interface 8-2, a third lower conductive interface 8-3, a fourth lower conductive interface 8-4, a fifth lower conductive interface 8-5, a sixth lower conductive interface 8-6, a seventh lower conductive interface 8-7 and an eighth lower conductive interface 8-8; each crystallizer lengthening part 6 is respectively provided with two upper conductive interfaces 5, namely a first upper conductive interface 5-1, a second upper conductive interface 5-2, a third upper conductive interface 5-3, a fourth upper conductive interface 5-4, a fifth upper conductive interface 5-5, a sixth upper conductive interface 5-6, a seventh upper conductive interface 5-7 and an eighth upper conductive interface 5-8; the two upper conductive interfaces 5 on each crystallizer lengthening part 6 are respectively positioned at the two ends of each crystallizer lengthening part 6;
crystallizer extensions on the first, second, third and fourth sections 14-1, 14-2, 14-3, 14-4 are integrally constructed with the first, second, third and fourth sections 14-1, 14-2, 14-3, 14-4, respectively;
the lower crystallizer 10 is provided with a liquid level detection probe 11, and the liquid level detection probe 11 is assembled on a liquid level detector;
a circular ring-shaped insulating gasket 9 is arranged between the upper crystallizer and the lower crystallizer 10;
one pole of the power supply 1 is connected with the upper conductive interface 5 and/or the lower conductive interface 8 through a short net, and the other pole is connected with the consumable electrode 2; the short net is provided with a switch 17;
the lower crystallizer 10 is provided with two liquid level detection probes 11, and the two liquid level detection probes 11 are jointly assembled on the same liquid level detector; the height difference of the two liquid level detection probes 11 is 15-20 mm; the projections of the axes of the two liquid level detection probes 11 on the horizontal plane form an included angle theta or are overlapped; the included angle θ=180°;
the method comprises the following steps:
the mandrel 3 is arranged in a T-shaped crystallizer, and the bottom surface of the mandrel 3 is connected with a dummy ingot plate 16; the dummy ingot plate 16 is connected with the bottom surface of the lower crystallizer lower part 14;
a coating layer 15 is arranged in the T-shaped crystallizer, and the space between the mandrel 3 and the lower crystallizer 10 is filled with the coating layer 15;
pouring the melted slag into a T-shaped crystallizer to form a liquid slag pool 4; one pole of the power supply 1 is connected with the upper conductive interface 5 and/or the lower conductive interface 8 through a short network, and the other pole is connected with the consumable electrode 2;
when one pole of the power supply 1 is simultaneously connected with each upper conductive interface 5 and each lower conductive interface 8 of the upper crystallizer to form a seventh combined connection mode, the current direction in the upper crystallizer is basically axial, and the current values are uniformly distributed along the circumferential direction; the nonuniform axial magnetic field generated by the crystallizer current is basically eliminated, so that the disturbance of the stray magnetic field in the T-shaped crystallizer is controlled, and the influence of the stray magnetic field on the liquid slag bath 4 and the metal molten pool 12 is weakened;
the consumable electrode 2 is a cylinder and consists of a plurality of cylinder consumable electrodes, the cylinder consumable electrodes are uniformly distributed on the periphery of the mandrel 3, and the distance between each cylinder consumable electrode and the mandrel 3 is equal;
lowering the consumable electrode 2 into the liquid slag bath 4 by a lifting device; closing the switch 17, and conducting the circuits of the consumable electrode 2, the liquid slag pool 4, the graphite ring 18 and the upper crystallizer; under the action of current, the temperature of the liquid slag pool 4 is gradually increased, the consumable electrode 2 is heated and melted, and the surface of the mandrel 3 is heated to form a melting layer; the molten metal drops formed by melting the consumable electrode 2 are deposited at the bottom of the liquid slag bath 4 to form a metal molten pool 12;
under the cooling action of the T-shaped crystallizer, the metal molten pool 12 is gradually cooled, and a cladding layer 13 is formed to wrap the outer wall of the mandrel 3; at this time, the ingot pulling system is started, the dummy ingot plate 16 is lowered, and the mandrel 3 wrapped with the cladding layer 13 is pulled out in the process of lowering the dummy ingot plate 16, so that a composite steel ingot is formed.
The diameter of the mandrel is 500mm; the inner diameter of the consumable electrode is 580mm, and the outer diameter is 720mm; the inner diameter of the graphite ring is 840mm, the outer diameter of the graphite ring is 920mm, the inner diameter of the upper conductive crystallizer is 920mm, and the outer diameter of the upper conductive crystallizer is 1080mm. The inner diameter of the cladding layer is 500mm, and the outer diameter is 680mm; the mandrel is made of forged 42CrMo steel, and the consumable electrode is Cr5 steel; the conducting interface of the electrode connection adopts a seventh combination mode; and the electroslag remelting is used for preparing the composite ingot, the stray magnetic field generated by the crystallizer current is basically eliminated, the slag pool and the metal molten pool perform uniform circulating flow, and the circumferential uniformity of the combination quality of the temperature field and the composite interface is good.
Example 2
The device structure is the same as that of example 1, except that:
the included angle θ=90°;
the process is the same as in example 1, except that:
when one pole of the power supply 1 is connected with the conductive interface, the connected conductive interfaces form a first combination; the first combination is that one pole of the power supply 1 is connected to the first upper conductive interface 5-1, the third upper conductive interface 5-3, the fifth upper conductive interface 5-5 and the seventh upper conductive interface 5-7;
the crystallizer current generates an axial magnetic field in the same direction, the slag bath and the metal molten pool perform the same-direction rotary flow, but the rotary flow is smaller, and the circumferential uniformity of the combined quality of the temperature field and the composite interface is slightly poor.
Example 3
The device structure is the same as that of example 1, except that:
the included angle θ=270°;
the process is the same as in example 1, except that:
when one pole of the power supply 1 is connected with the conductive interface, the connected conductive interfaces form a second combination; the second combination is that one pole of the power supply 1 is connected to the first conductive interface 5-1 and the fifth upper conductive interface 5-5, meanwhile, the third upper conductive interface 5-3 and the fourth upper conductive interface 5-4 are connected through a wire, and the seventh upper conductive interface 5-7 and the eighth upper conductive interface 5-8 are connected through a wire;
the crystallizer current generates an axial magnetic field in the same direction, the slag pool and the metal molten pool perform the same-direction rotary flow, the rotary flow speed of the slag pool is moderate, and the circumferential uniformity of the combination quality of the temperature field and the composite interface is good.
Example 4
The device structure is the same as in example 1;
the process is the same as in example 1, except that:
when one pole of the power supply 1 is connected with the conductive interface, the connected conductive interfaces form a third combination; the third combination is that one pole of the power supply 1 is connected to the first upper conductive interface 5-1, meanwhile, the third upper conductive interface 5-3 and the fourth upper conductive interface 5-4 are connected through a wire, the fifth upper conductive interface 5-5 and the sixth upper conductive interface 5-6 are connected through a wire, and the seventh upper conductive interface 5-7 and the eighth upper conductive interface 5-8 are connected through a wire;
the crystallizer current is in the same-direction axial magnetic field, the slag pool and the metal molten pool perform the same-direction rotary flow, the rotary flow speed of the slag pool is too high, the circumferential uniformity of the combination quality of the temperature field and the composite interface is good, but the temperature of the slag pool is reduced, and the effective power is reduced.
Example 5
The device structure is the same as in example 1;
the process is the same as in example 1, except that:
when one pole of the power supply 1 is connected with the conductive interface, the connected conductive interfaces form a fourth combination; one pole of the fourth combined electrode is connected to the first lower conductive interface 8-1, the third lower conductive interface 8-3, the fifth lower conductive interface 8-5 and the seventh lower conductive interface 8-7;
the crystallizer current generates an axial magnetic field in the same direction, the slag bath and the metal molten pool perform the same-direction rotary flow, but the rotary flow is smaller, and the circumferential uniformity of the combined quality of the temperature field and the composite interface is slightly poor.
Example 6
The device structure is the same as that of example 1, except that:
the included angle θ=90°;
the process is the same as in example 1, except that:
when one pole of the power supply 1 is connected with the conductive interface, the connected conductive interfaces form a fifth combination; the fifth combination is that one pole of the power supply 1 is connected to the first lower conductive interface 8-1 and the fifth lower conductive interface 8-5, meanwhile, the third lower conductive interface 8-3 and the fourth lower conductive interface 8-4 are connected through a wire, and the seventh lower conductive interface 8-7 and the eighth lower conductive interface 8-8 are connected through a wire;
the crystallizer current is in the same-direction axial magnetic field, the slag pool and the metal molten pool perform the same-direction rotary flow, the rotary flow speed of the slag pool is moderate, and the circumferential uniformity of the combination quality of the temperature field and the composite interface is good.
Example 7
The device structure is the same as that of example 1, except that:
the included angle θ=270°;
the process is the same as in example 1, except that:
when one pole of the power supply 1 is connected with the conductive interface, the connected conductive interfaces form a sixth combination; the sixth combination is that one pole of the power supply 1 is connected to the first lower conductive interface 8-1, the third lower conductive interface 8-3 and the fourth lower conductive interface 8-4 are connected through a wire, the fifth lower conductive interface 8-5 and the sixth lower conductive interface 8-6 are connected through a wire, and the seventh lower conductive interface 8-7 and the eighth lower conductive interface 8-8 are connected through a wire;
the crystallizer current is in the same-direction axial magnetic field, the slag pool and the metal molten pool perform the same-direction rotary flow, the rotary flow speed of the slag pool is moderate, and the circumferential uniformity of the combination quality of the temperature field and the composite interface is good.
Claims (6)
1. A device for preparing composite steel ingots based on a conductive crystallizer comprises a T-shaped crystallizer, a dummy ingot plate and a power supply; the T-shaped crystallizer consists of an upper crystallizer and a lower crystallizer; the method is characterized in that: an upper crystallizer lengthening part is arranged at the upper part of the outer wall of the upper crystallizer, an upper conductive interface is arranged on the outer wall of the crystallizer lengthening part, and a lower conductive interface is arranged at the lower part of the outer wall of the upper crystallizer;
the upper crystallizer consists of a first part, a second part, a third part and a fourth part which are identical in shape and size, wherein the first part, the second part, the third part and the fourth part are arc-shaped plates; the upper crystallizer is internally provided with a cylindrical graphite ring, and the outer wall surface of the graphite ring is simultaneously connected with the first part, the second part, the third part and the fourth part; the first part, the second part, the third part and the fourth part are arranged around the graphite ring, two adjacent parts are connected with a platy insulating gasket together, and a total of four insulating gaskets are respectively a first insulating gasket, a second insulating gasket, a third insulating gasket and a fourth insulating gasket; the upper parts of the outer walls of the first part, the second part, the third part and the fourth part are respectively provided with an arc-shaped platy crystallizer lengthening part, and the total number of the crystallizer lengthening parts of the upper crystallizer is four, namely a first lengthening part, a second lengthening part, a third lengthening part and a fourth lengthening part; a gap is reserved between two adjacent crystallizer lengthening parts; the lower parts of the outer walls of the first part, the second part, the third part and the fourth part are respectively provided with two lower conductive interfaces, the two lower conductive interfaces of each part are respectively positioned at two ends of each part, and the two lower conductive interfaces are respectively a first lower conductive interface, a second lower conductive interface, a third lower conductive interface, a fourth lower conductive interface, a fifth lower conductive interface, a sixth lower conductive interface, a seventh lower conductive interface and an eighth lower conductive interface; each crystallizer lengthening part is respectively provided with two upper conductive interfaces, namely a first upper conductive interface, a second upper conductive interface, a third upper conductive interface, a fourth upper conductive interface, a fifth upper conductive interface, a sixth upper conductive interface, a seventh upper conductive interface and an eighth upper conductive interface; the two upper conductive interfaces on each crystallizer lengthening part are respectively positioned at the two ends of each crystallizer lengthening part.
2. An apparatus for preparing composite steel ingots based on conductive crystallizer as claimed in claim 1, wherein the crystallizer lengthening parts on the first, second, third and fourth parts are respectively integrated with the first, second, third and fourth parts.
3. The apparatus for preparing composite steel ingots based on the conductive crystallizer as claimed in claim 1, wherein the liquid level detecting probe is installed on the lower crystallizer, and the liquid level detecting probe is assembled on the liquid level detecting instrument.
4. The device for preparing composite steel ingots based on the conductive crystallizer as claimed in claim 1, wherein one pole of the power supply is connected with the upper conductive interface and/or the lower conductive interface through a short net, and the other pole is connected with the consumable electrode; the short net is provided with a switch.
5. A method for preparing a composite steel ingot based on a conductive crystallizer, characterized in that the device of claim 1 is adopted, and the method comprises the following steps:
(1) Placing a mandrel in a T-shaped crystallizer, and connecting the bottom surface of the mandrel with a dummy ingot plate; at this time, the dummy ingot plate is connected with the bottom surface of the lower part of the lower crystallizer;
(2) A coating layer is arranged in the T-shaped crystallizer, and the space between the mandrel and the lower crystallizer is filled with the coating layer;
(3) Pouring the molten slag into a T-shaped crystallizer to form a liquid slag pool; connecting one pole of the power supply with the upper conductive interface and/or the lower conductive interface through a short network, and connecting the other pole with the consumable electrode;
(4) Lowering the consumable electrode into the liquid slag pool through the lifting device; closing the switch, and conducting the circuits of the consumable electrode, the liquid slag pool, the graphite ring and the upper crystallizer; under the action of current, the temperature of the liquid slag pool is gradually increased, the consumable electrode is heated and melted, and the surface of the mandrel is heated to form a melting layer; the metal liquid drops formed by melting the consumable electrode are deposited at the bottom of the liquid slag pool to form a metal molten pool;
(5) Under the cooling action of the T-shaped crystallizer, the metal molten pool is gradually cooled, and a cladding layer is formed to wrap the outer wall of the mandrel; at the moment, starting an ingot pulling system, lowering a dummy ingot plate, and pulling out a mandrel wrapped with a cladding layer in the process of lowering the dummy ingot plate to form a composite steel ingot;
in the step (3), when one pole of the power supply is connected with the conductive interface, the power supply is connected in a first combination, a second combination, a third combination, a fourth combination, a fifth combination or a sixth combination; a pole of the first combined power supply is connected to the first upper conductive interface, the third upper conductive interface, the fifth upper conductive interface and the seventh upper conductive interface; the second electrode of the power supply is connected to the first conductive interface and the fifth upper conductive interface, meanwhile, the third upper conductive interface and the fourth upper conductive interface are connected through a wire, and the seventh upper conductive interface and the eighth upper conductive interface are connected through a wire; the third combination is that one pole of the power supply is connected to the first upper conductive interface, meanwhile, the third upper conductive interface is connected with the fourth upper conductive interface through a wire, the fifth upper conductive interface is connected with the sixth upper conductive interface through a wire, and the seventh upper conductive interface is connected with the eighth upper conductive interface through a wire; a fourth combined power supply with one pole connected to the first lower conductive interface, the third lower conductive interface, the fifth lower conductive interface and the seventh lower conductive interface; the fifth combination is that one pole of the power supply is connected to the first lower conductive interface and the fifth lower conductive interface, meanwhile, the third lower conductive interface and the fourth lower conductive interface are connected through a wire, and the seventh lower conductive interface and the eighth lower conductive interface are connected through a wire; the sixth combination is that one pole of the power supply is connected to the first lower conductive interface, the third lower conductive interface is connected with the fourth lower conductive interface through a wire, the fifth lower conductive interface is connected with the sixth lower conductive interface through a wire, and the seventh lower conductive interface is connected with the eighth lower conductive interface through a wire.
6. The method for manufacturing a composite steel ingot based on a conductive mold according to claim 5, wherein in the step (3), the consumable electrode is of a cylindrical type or of a cylindrical type; when the consumable electrode is cylindrical, the consumable electrode consists of a plurality of cylindrical consumable electrodes which are uniformly distributed on the periphery of the mandrel, and the distance between each cylindrical consumable electrode and the mandrel is equal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210253313.2A CN114854994B (en) | 2022-03-15 | 2022-03-15 | Device and method for preparing composite steel ingot based on conductive crystallizer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210253313.2A CN114854994B (en) | 2022-03-15 | 2022-03-15 | Device and method for preparing composite steel ingot based on conductive crystallizer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114854994A CN114854994A (en) | 2022-08-05 |
| CN114854994B true CN114854994B (en) | 2023-04-28 |
Family
ID=82627828
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210253313.2A Active CN114854994B (en) | 2022-03-15 | 2022-03-15 | Device and method for preparing composite steel ingot based on conductive crystallizer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114854994B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115710640A (en) * | 2022-12-08 | 2023-02-24 | 东北大学 | Split conductive crystallizer and electroslag remelting device and method for improving molten pool distribution |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2082788C1 (en) * | 1994-02-18 | 1997-06-27 | Товарищество с ограниченной ответственностью Экспериментальная фирма "Экомет" | Installation for electroslag remelting and smelting |
| CN113061741B (en) * | 2021-03-18 | 2022-05-03 | 东北大学 | Electroslag remelting composite device and method for improving temperature distribution of slag bath by external magnetic field |
| CN113547102B (en) * | 2021-07-23 | 2022-03-22 | 东北大学 | Device and method for preparing large steel ingot by conductive crystallizer electroslag remelting method |
-
2022
- 2022-03-15 CN CN202210253313.2A patent/CN114854994B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN114854994A (en) | 2022-08-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113061741B (en) | Electroslag remelting composite device and method for improving temperature distribution of slag bath by external magnetic field | |
| CN105522126B (en) | The compound roll shaft manufacturing process of high-performance and equipment | |
| CN111590054B (en) | Device and method for preparing bimetal clad roller by ingot drawing type electroslag remelting method | |
| CN114854994B (en) | Device and method for preparing composite steel ingot based on conductive crystallizer | |
| CN102310174B (en) | Method and device for improving metal solidification defects and refining solidification textures | |
| CN105522138B (en) | A kind of forged steel roll neck rich chromium cast iron composite roll Processes and apparatus | |
| CN108746562B (en) | Device and method for preparing large composite steel ingot by graphite electrode ring preheating electroslag casting | |
| CN101293273A (en) | Process for manufacturing low-aliquation large-scale hollow steel ingot | |
| CN103212675A (en) | Steel ingot feeder head induction heating and electromagnetic stirring device | |
| CN105562647B (en) | A kind of forged steel roll neck indefinite chill high-nickel-chromium molybdenum composite roll Processes and apparatus | |
| CN105312541A (en) | Improved technique and device for manufacturing nickel-chromium molybdenum alloy cast iron composite roller in forged steel roller neck | |
| CN107262686A (en) | A kind of device and method for preparing compound steel ingot | |
| CN104152709A (en) | Production process for corrosion resistant alloy electroslag remelting slab with thickness smaller than 200 mm and equipment | |
| CN102189246A (en) | Method and device for manufacturing hollow melt ingots | |
| CN107363252A (en) | The flow control device and method of Cleanliness of Molten Steel in a kind of raising casting process | |
| CN113426970A (en) | Vertical semi-continuous production device and production process of large round billets with phi of 1000 mm-2000 mm | |
| CN101122441B (en) | Short cold crucible for continuous melting and directional solidification flat blank | |
| CN112238212B (en) | Double-roller thin-strip casting-rolling electromagnetic extrusion type metal molten pool side sealing method and side sealing device thereof | |
| CN111730036B (en) | Same-level electromagnetic casting device and method | |
| CN101298092B (en) | Method for producing movable core low segregation large-sized hollow steel ingot | |
| CN109128103B (en) | Device and method for preparing composite roller/composite steel ingot by electroslag casting method | |
| CN201201039Y (en) | Casting apparatus for low aliquation large-sized hollow steel ingot | |
| CN203235929U (en) | Induction heating and electromagnetic stirring device for riser of steel ingot | |
| CN109396409B (en) | Single-point non-equilibrium protection casting method for producing ultrathin large-size aluminum-containing steel special-shaped blank | |
| CN2356783Y (en) | Device for molten metal electroslag continuous casting ingot and pile-up welding |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |