Wide-surface back plate structure of composite magnetic field continuous casting crystallizer

Abstract

Stainless steel side plates of the structure are arranged on the two sides of the lower portion of a stainless steel main plate, and a stainless steel bottom plate is arranged on the bottom face of the stainless steel main plate. A water inlet channel and a water return channel are arranged on the lower portion of the stainless steel main board, the iron core is arranged on the lower portion of the stainless steel main board and located between the water inlet channel and the water return channel, and a plurality of square holes communicated with the water inlet channel are formed in the connecting face of the lower portion of the stainless steel main board and a crystallizer copper plate. A plurality of deep holes communicated with the water return channel are formed in the connecting face of the upper portion of the stainless steel main plate and the crystallizer copper plate, the stainless steel side plates on the two sides of the stainless steel main plate are provided with water inlets and water return ports communicated with the water inlet channel and the water return channel, and the water tank is arranged on the stainless steel side plates on the two sides of the stainless steel main plate and provided with through holes communicated with the water inlets and the water return ports. According to the structure, the occupied space of the crystallizer water tank is reduced, the installation space is provided for composite magnetic field corollary equipment in the crystallizer, and the requirement of an electromagnetic braking device for magnetic flux is met.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical mechanical continuous casting, and in particular to a wide-surface back plate structure of a composite magnetic field continuous casting crystallizer. Background Art

[0002] Continuous casting is the main process of steelmaking. Most of the world's total steel is obtained through continuous casting. The crystallizer is known as the "heart" of the continuous casting machine. The quality of the casting is closely related to the crystallizer. With the development of continuous casting technology, electromagnetic technology is increasingly being applied to continuous casting.

[0003] The composite magnetic field continuous casting crystallizer is a crystallizer that integrates electromagnetic stirring EMS and electromagnetic braking EMBR. Electromagnetic stirring technology (EMS) is to generate an induced current in the metal melt after the metal is melted at high temperature. The electromagnetic force is controlled by an electromagnetic generating device. The electromagnetic force controls the heat transfer, fluidity and solidification process of the metal melt, thereby reducing the segregation of the equiaxed crystal zone of the casting, improving the cleanliness of the metal casting, reducing the probability of defects in the finished casting, and effectively improving the quality of the casting.

[0004] In the continuous casting process system, the electromagnetic brake (EMBR) device is a technical means that guides the molten steel in the crystallizer to flow in a specific direction, controls the flow rate of the molten steel and suppresses eddy currents by forming a static magnetic field under power-on conditions. It plays multiple roles such as stabilizing the crystallizer liquid level, increasing the meniscus temperature, and reducing the inclusion content of the molten steel.

[0005] With the continuous development of science and technology, the current continuous casting electromagnetic process technology has undergone earth-shaking changes compared with the last century, and has been significantly applied in electromagnetic process control systems, effectively improving the efficiency of continuous casting equipment. In recent years, crystallizers using electromagnetic technology (including electromagnetic stirring technology and electromagnetic braking technology) have been widely used in the steel industry. Electromagnetic stirring and electromagnetic braking devices have been applied to crystallizers of multiple continuous casting production lines, but there is no precedent in China for combining the two devices and installing them in the same crystallizer. Recently, through theoretical research, the application of the two technologies to a crystallizer to form a composite magnetic field of electromagnetic stirring and electromagnetic braking can further improve the quality of castings, providing a new development direction for the subsequent development of electromagnetic technology.

[0006] During the continuous casting process, the cooling water in the crystallizer can take away the heat of the copper plate and maintain the surface temperature of the copper plate within a reasonable range, which has an important impact on the quality of the continuous casting billet. The wide surface of the domestic crystallizer mostly uses a combination of a water tank and a back plate to complete the diversion and transmission of cooling water. The cooling water enters the back plate through the circular hole below the water inlet channel in the water tank and then enters the copper plate groove. After cooling the copper plate, the cooling water enters the circular hole on the upper part of the back plate and finally enters the water tank return water channel. Therefore, how to improve the crystallizer structure and install the two electromagnetic devices in one crystallizer at the same time without affecting the transmission of cooling water is also a topic that needs further research in the future. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a wide back plate structure for a composite magnetic field continuous casting crystallizer. While retaining the original cooling function of the crystallizer copper plate, this structure transfers the diversion and transmission control function of the traditional water tank on cooling water to the back plate, greatly reducing the space occupied by the crystallizer water tank, providing installation space for composite magnetic field supporting equipment in the crystallizer, and meeting the requirements of the electromagnetic braking device for magnetic flux.

[0008] In order to solve the above technical problems, the wide back plate structure of the composite magnetic field continuous casting crystallizer of the present invention comprises a stainless steel main plate, a stainless steel side plate, a stainless steel bottom plate and an iron core, wherein the stainless steel side plates are respectively arranged on both sides of the lower part of the stainless steel main plate, and the stainless steel bottom plate is arranged on the bottom surface of the stainless steel main plate, and the stainless steel main plate, the stainless steel side plate and the stainless steel bottom plate constitute a stepped wide back plate which is narrow at the top and wide at the bottom; An inlet channel and a return channel are provided at the lower part of the stainless steel main board, the iron core is provided at the lower part of the stainless steel main board and is located between the inlet channel and the return channel, a plurality of square holes are provided at the lower part of the stainless steel main board and the connection surface of the crystallizer copper plate to connect the inlet channel, a plurality of deep holes are provided at the upper part of the stainless steel main board and the connection surface of the crystallizer copper plate to connect the return channel, the cooling water enters the groove of the crystallizer copper plate through the inlet channel and the plurality of square holes, and then flows into the return channel through the plurality of deep holes, the stainless steel side plates on both sides of the stainless steel main board are provided with a water inlet and a return port to connect the inlet channel and the return channel respectively, the water tank is provided on the stainless steel side plates on both sides of the stainless steel main board by bolts, and through holes to connect the inlet and the return port are provided at both ends of the water tank respectively.

[0009] Furthermore, a sealing ring is provided between the water inlet of the stainless steel side plate and the through hole of the water tank.

[0010] Furthermore, the stainless steel main board is provided with a thermocouple mounting hole, a water-blocking sleeve is provided in the thermocouple mounting hole, and an O-ring is provided on the mating surface between the water-blocking sleeve and the stainless steel main board.

[0011] Furthermore, the spacing between the plurality of square holes at the bottom of the stainless steel main board is 80 mm.

[0012] Furthermore, the diameter of the several deep holes on the upper part of the stainless steel main board is 28 mm and the spacing is 80 mm.

[0013] Furthermore, the water inlet and water return port of the stainless steel side plates on both sides of the stainless steel main board are square holes of 100×180 mm. Since the wide-surface back plate structure of the composite magnetic field continuous casting crystallizer of the present invention adopts the above-mentioned technical scheme, that is, the stainless steel side plates of the structure are respectively arranged on both sides of the lower part of the stainless steel main board, and the stainless steel bottom plate is arranged on the bottom surface of the stainless steel main board; the lower part of the stainless steel main board is provided with an inlet waterway and a return waterway, the iron core is arranged at the lower part of the stainless steel main board and is located between the inlet waterway and the return waterway, the lower part of the stainless steel main board and the connection surface of the crystallizer copper plate are provided with a plurality of square holes connected to the inlet waterway, and the upper part of the stainless steel main board and the connection surface of the crystallizer copper plate are provided with a plurality of deep holes connected to the return waterway, the cooling water enters the groove of the crystallizer copper plate through the inlet waterway and the plurality of square holes, and then flows into the return waterway through the plurality of deep holes, the stainless steel side plates on both sides of the stainless steel main board are respectively provided with a water inlet and a return waterway connected to the inlet waterway and the return waterway, and the water tank is provided with the stainless steel side plates on both sides of the stainless steel main board by bolts and is provided with a through hole connecting the inlet waterway and the return waterway. This structure retains the original crystallizer copper plate cooling function while transferring the traditional water tank's control of cooling water diversion transmission to the back plate, greatly reducing the space occupied by the crystallizer water tank, providing installation space for composite magnetic field supporting equipment in the crystallizer, and meeting the requirements of the electromagnetic brake device for magnetic flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic diagram of the wide back plate structure of the composite magnetic field continuous casting crystallizer of the present invention; Figure 2 This is a schematic diagram of the connection between the water tank and the stainless steel side plate in this structure; Figure 3 This is a schematic diagram of the installation of the stainless steel mainboard waterproof sleeve in this structure. DETAILED DESCRIPTION

[0015] Implementation example Figure 1 and Figure 2 As shown, the wide back plate structure of the composite magnetic field continuous casting crystallizer of the present invention comprises a stainless steel main plate 1, a stainless steel side plate 2, a stainless steel bottom plate 3 and an iron core 4, wherein the stainless steel side plates 2 are respectively arranged on both sides of the lower part of the stainless steel main plate 1, and the stainless steel bottom plate 3 is arranged on the bottom surface of the stainless steel main plate 1, and the stainless steel main plate 1, the stainless steel side plates 2 and the stainless steel bottom plate 3 constitute a stepped wide back plate which is narrow at the top and wide at the bottom; The lower part of the stainless steel main board 1 is provided with an inlet channel 11 and a return channel 12, the iron core 4 is provided at the lower part of the stainless steel main board 1 and is located between the inlet channel 11 and the return channel 12, the lower part of the stainless steel main board 1 and the connection surface of the crystallizer copper plate are provided with a plurality of square holes 13 connected to the inlet channel 11, and the upper part of the stainless steel main board 1 and the connection surface of the crystallizer copper plate are provided with a plurality of deep holes 14 connected to the return channel 12, the cooling water enters the groove of the crystallizer copper plate through the inlet channel 11 and the plurality of square holes 13, and then flows into the return channel 12 through the plurality of deep holes 14, the stainless steel side plates 2 on both sides of the stainless steel main board 1 are provided with a water inlet 21 and a return port 22 connected to the inlet channel 11 and the return channel 12, respectively, the water tank 5 is provided on the stainless steel side plates 2 on both sides of the stainless steel main board 1 by bolts 51, and through holes 52 connected to the inlet 21 and the return port 22 are provided at both ends of the water tank 5.

[0016] The return port and water inlet of the stainless steel side panel are respectively connected to the cavities at both ends of the water tank. The structure of the water tank plays a transitional intermediary role in the connection process of the water path. The cavities at the left and right ends of the water tank are not connected, and are respectively connected to the return system and water inlet system on the supporting frame, finally forming a cooling cycle.

[0017] Preferably, a sealing ring 53 is provided between the water inlet 21 of the stainless steel side plate 2 and the through hole 52 of the water tank 5 .

[0018] Preferably, Figure 3 As shown, the stainless steel main board 1 is provided with a thermocouple mounting hole 15 , a water-blocking sleeve 16 is provided in the thermocouple mounting hole 15 , and an O-ring 17 is provided on the mating surface between the water-blocking sleeve 16 and the stainless steel main board 1 .

[0019] Preferably, the spacing between the plurality of square holes 13 at the lower portion of the stainless steel main board 1 is 80 mm.

[0020] Preferably, the diameter of the plurality of deep holes 14 on the upper portion of the stainless steel main board 1 is 28 mm and the spacing is 80 mm.

[0021] Preferably, the water inlet 21 and the water return port 22 of the stainless steel side plates 2 on both sides of the stainless steel main plate 1 are square holes of 100×180 mm.

[0022] In this structure, the wide back plate is welded by a stainless steel main plate, two stainless steel side plates and a stainless steel bottom plate. The two stainless steel side plates are used to carry the water tank and are provided with an inlet and a return port connecting the water inlet and return channels. The bottom of the stainless steel bottom plate is the mounting surface for mounting the wide-edge foot roller. In order to reduce welding deformation, the stainless steel bottom plate is welded in two pieces, and the bottom is reinforced by welding ribs. The stainless steel bottom plate is through-tapped with M36 threaded holes, and M36 bolts are installed during assembly to support the electromagnetic brake device.

[0023] In order to meet the process parameter requirement that the cross-sectional area of ​​the inlet and outlet water channels should be 1.5 times larger than the cross-sectional area of ​​the copper plate groove of the crystallizer, and to allow the wide back plate to have enough space to design the inlet and outlet water channels, the lower part of the stainless steel main plate is widened by welding stainless steel side plates, so that the upper part of the stainless steel main plate leaves enough installation space for the electromagnetic stirring and braking devices. Therefore, under the premise of retaining the original wide back plate design structure, the wide back plate is designed to be a stepped structure that is narrow at the top and wide at the bottom.

[0024] Inlet and outlet water channels and installation grooves for two iron cores are milled on the stainless steel main board. Inlet and return water channels for cooling water inside the stainless steel main board are formed by watertight welding. Two iron cores are installed in the installation grooves. The iron cores are used to increase the magnetic flux of the electromagnetic braking device. The inlet water channel and the return water channel are separated by watertight welding of the two iron cores and the steel plate. The upper part is the return water channel, and the lower part is the inlet water channel. Several square holes connected to the inlet water channel are opened on the side where the inlet water channel is connected to the crystallizer copper plate. Several deep holes connected to the return water channel are opened on the upper part of the stainless steel main board. The cooling water enters the copper plate groove from the inlet water channel through the square holes, enters the deep holes from the groove, and finally enters the return water channel to complete the cooling of the crystallizer copper plate.

[0025] The cooling water flow inside the continuous casting crystallizer is an important factor affecting the cooling effect of the crystallizer copper plate on the solidification of molten steel, especially the change of the cooling water channel, which in turn affects the heat transfer of the crystallizer. In order to study the cooling water flow inside the improved continuous casting crystallizer and the deformation and stress of the wide back plate, the cooling water flow inside the crystallizer, the heat transfer on the copper plate surface, the deformation and stress of the wide back plate are simulated by computer simulation. These analysis results can provide important references for the design and optimization of the crystallizer back plate. The specific technical solution is described as follows: A statics model of the crystallizer is established. Under statics, the stress must satisfy the stress equilibrium equation and the strain coordination equation. The stress and strain must satisfy the constitutive relationship. The model is discretized and solved using the Ansys statics module.

[0026] The assembly model (including water tank, wide back plate, copper plate, electromagnetic brake, and foot roller) was simplified and meshed. The wide back plate was simplified as little as possible, and other components were simplified. After simplification, a total of 2.07 million meshes were obtained, which met the mesh requirements of static analysis.

[0027] The following table shows the mechanical properties of the materials of each component in this structure: Material Density (kg / m3) Elastic modulus (GPa) Poisson's ratio Wide back plate (022Cr119Ni10 alloy) 7860 200 0.29 Iron core (Q235 alloy) 7850 210 0.33 Crystallizer copper plate (Cr-Zr-Al-Cu alloy) 8940 128 0.18 The table gives the material mechanical properties and load boundary conditions of each component of this structure. During the continuous casting process, each component is mainly subjected to four loads: gravity, including the gravity of electromagnetic brakes and other components; 2. Static pressure of molten steel; 3. Water pressure; 4. Clamping force. The weight of the electromagnetic stirring device is 2 tons, and the weight of the electromagnetic brake device is 4 tons. The static pressure of molten steel is mainly caused by the weight of the molten steel itself on the copper plate. The static pressure of molten steel on the copper plate is simulated with the free surface of the molten steel as the reference point. The static pressure caused by the molten steel on the copper plate is linearly distributed, reaching a maximum of about 0.06 MPa at the bottom of the copper plate. The upper clamping force is 81 kN and the lower clamping force is 105 kN. In addition, the water pressure in the inner cavity is calculated according to the flow heat transfer model and added to each surface as an average surface load. The area where the copper plates contact each other, the area where the clamping device contacts the frame, and the area supported by the frame are used as displacement boundary conditions to completely limit the displacement.

[0028] According to calculations, the maximum stress of the wide back plate under the action of equipment gravity, molten steel static pressure, water pressure and clamping force is 52.2MPa, and the maximum displacement is 0.13 mm. The stress is less than the yield strength of the material of each component. The maximum deformation is mainly located at the corners on both sides of the support frame, and the stress is mainly distributed near the clamping device and in the area where the wide and narrow surfaces of the copper plate contact each other.

[0029] The control equations of fluid flow heat transfer and solid heat transfer in the crystallizer are established, and the assembly model is simplified to meet the simulation conditions. Focus is placed on the flow of cooling water and the heat transfer of the copper plate. The fluid domain (water channel) and solid domain (copper plate) are mainly retained. The simplified model is divided into tetrahedral grids in Ansys workbench, and the curvature and slits are captured. The overall grid size is about 1-10 mm, and the final number of grids is about 8 million.

[0030] The material properties used for flow heat transfer are given, and the boundary conditions of heat transfer and flow heat transfer calculation models are determined. The simulation adopts transient simulation, and the SIMPLE algorithm with pressure-velocity coupling semi-implicit format is used to solve the flow. Combined with the on-site casting process parameters, the cooling water flow direction, flow rate and temperature field evolution on the surface of the wide back plate and copper plate are simulated and analyzed. When the surface temperature of the copper plate no longer changes (the maximum temperature changes by about 1°C every 5 seconds), the temperature field is considered to be stable and the calculation is stopped.

[0031] The cooling water flow rate in the water-cooling groove in the copper plate basically meets the process requirements. The results of the simulation calculation of cooling water flow and copper plate heat transfer are as follows: in terms of cooling water flow, the water flow rate in the copper plate groove inside the crystallizer before and after the improvement is about 10-20 m / s; in terms of copper plate heat transfer, the maximum temperature difference of the copper plate surface temperature of the crystallizer before and after the improvement at each moment is about 0-4℃.

[0032] Through simulation analysis, it is concluded that the strength of this structure and the flow and heat transfer of the cooling circulating water therein meet the requirements. This structure integrates some functions of the water tank into the wide back plate structure, providing conditions for the installation of electromagnetic brakes while meeting the strength and flow and heat transfer of the cooling circulating water, and meeting its requirements for magnetic flux. Actual use shows that this structure can further improve the quality of castings, which is an important direction for the development of continuous casting technology. This structure also has important application and promotion value.

Claims

1. A wide back plate structure of a composite magnetic field continuous casting crystallizer, characterized in that: It comprises a stainless steel main board, a stainless steel side board, a stainless steel bottom board and an iron core, wherein the stainless steel side boards are respectively arranged on both sides of the lower part of the stainless steel main board, and the stainless steel bottom board is arranged on the bottom surface of the stainless steel main board, and the stainless steel main board, the stainless steel side board and the stainless steel bottom board form a stepped wide-surface back board which is narrow at the top and wide at the bottom; An inlet channel and a return channel are provided at the lower part of the stainless steel main board, the iron core is provided at the lower part of the stainless steel main board and is located between the inlet channel and the return channel, a plurality of square holes are provided at the lower part of the stainless steel main board and the connection surface of the crystallizer copper plate to connect the inlet channel, a plurality of deep holes are provided at the upper part of the stainless steel main board and the connection surface of the crystallizer copper plate to connect the return channel, the cooling water enters the groove of the crystallizer copper plate through the inlet channel and the plurality of square holes, and then flows into the return channel through the plurality of deep holes, the stainless steel side plates on both sides of the stainless steel main board are provided with a water inlet and a return port to connect the inlet channel and the return channel respectively, the water tank is provided on the stainless steel side plates on both sides of the stainless steel main board by bolts, and through holes to connect the inlet and the return port are provided at both ends of the water tank respectively.

2. The wide back plate structure of the composite magnetic field continuous casting crystallizer according to claim 1, characterized in that: A sealing ring is arranged between the water inlet of the stainless steel side plate and the through hole of the water tank.

3. The wide back plate structure of the composite magnetic field continuous casting crystallizer according to claim 1 or 2, characterized in that: The stainless steel main board is provided with a thermocouple mounting hole, a water-blocking sleeve is provided in the thermocouple mounting hole, and an O-ring is provided on the matching surface of the water-blocking sleeve and the stainless steel main board.

4. The wide back plate structure of the composite magnetic field continuous casting crystallizer according to claim 3 is characterized in that: The spacing between the plurality of square holes at the bottom of the stainless steel main board is 80 mm.

5. The wide back plate structure of the composite magnetic field continuous casting crystallizer according to claim 3 is characterized in that: The diameter of the deep holes on the upper part of the stainless steel main board is 28 mm and the spacing is 80 mm.

6. The wide back plate structure of the composite magnetic field continuous casting crystallizer according to claim 3, characterized in that: The water inlet and water return port of the stainless steel side plates on both sides of the stainless steel main board are square holes of 100×180 mm.

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