Magnetic pulse generation cast-rolling casting nozzle with solidification structure regulation and control effect

Abstract

The invention relates to the technical field of magnesium alloy material processing, in particular to a magnetic pulse generation cast-rolling casting nozzle with a solidification structure regulation effect, which comprises a casting nozzle main body unit, a transmission unit and a magnetic pulse generation unit. The motor drives the coil box to move to the position close to the roller along the guide rail, so that a pulse electromagnetic field generated by the coil accurately acts on the solidification front edge; a plurality of positioning grooves are formed in the coil box, the coil can be divided into a middle coil and an edge coil, pulse electromagnetic fields are generated by utilizing currents with different intensities and frequencies at the edge and the middle, a solidification structure generates an induced magnetic field and is subjected to the action of Lorentz force, structure exchange is formed, and the consistency of the temperatures of the middle and the edges of a cast-rolling area is guaranteed; therefore, the shape of the cast-rolling solidification welding line is regulated and controlled. The method can promote nucleation at the solidification front edge, effectively refine the solidification structure, reduce macrosegregation, improve the problem of non-uniform cooling of the casting-rolling middle part and the casting-rolling edge part and effectively inhibit magnesium alloy casting-rolling edge cracks, and has important application value in the casting-rolling field.

Description

Technical Field

[0001] The invention relates to the technical field of magnesium alloy material processing, and in particular to a magnetic pulse casting and rolling nozzle with a solidification structure regulating function. Background Art

[0002] Magnesium and magnesium alloys have excellent specific strength, specific stiffness, impact resistance and good machinability, and have great potential in applications in high-performance automobiles, aerospace, 3C and other scientific and technological fields. Compared with traditional hot rolling, cast-rolled magnesium alloys have the advantages of short process, good formability and low cost. However, due to the small specific heat capacity of magnesium alloys and fast heat dissipation, the casting and rolling has the problem of uneven cooling rate. The magnesium alloy melt at the edge of the casting and rolling zone and near the surface of the casting and rolling roller solidifies first. Therefore, a ")"-shaped solidification weld line is generated along the width of the plate in the casting and rolling zone, which makes it very easy to cause edge cracks during the casting and rolling process. At the same time, the cast-rolled plate has problems such as uneven structure and segregation.

[0003] Based on the Lorentz force effect and Joule heat effect of pulsed electromagnetic field, the present invention develops a magnetic pulse casting nozzle with solidification structure regulation function. By introducing pulsed electromagnetic field at the casting nozzle, nucleation at the solidification front is promoted, the solidification structure is effectively refined, and macro segregation is reduced. At the same time, the Lorentz force of pulsed electromagnetic field is generated by currents of different strengths and frequencies at the edge and middle to ensure the consistency of temperature between the middle and edge of the casting and rolling zone, so as to regulate the shape of the casting and rolling solidification weld line, and the solidification weld line can be transformed from a ")" shape to a "1" shape, such as Figure 8 As shown, the purpose of inhibiting edge cracks in casting and rolling, refining grains and homogenizing the structure is achieved. Summary of the invention

[0004] In order to solve the current problems in magnesium alloy casting and rolling, the present invention introduces an induced electromagnetic field generated by a pulsed electromagnetic field at the casting nozzle to force the melt at the solidification front to circulate, thereby achieving position and shape regulation of the solidification weld line to reduce edge cracks in the magnesium alloy, refine grains, homogenize the structure and reduce macro-segregation.

[0005] To achieve the above-mentioned purpose, the present invention provides the following scheme: A magnetic pulse generating casting and rolling nozzle with a solidification structure regulating function, the device comprising: a nozzle main body unit consisting of a nozzle upper plate (1), a guide plate (2), and a nozzle lower plate (3); the nozzle guide plate is fixed between the nozzle upper plate and the nozzle lower plate; the transmission unit consists of two pairs of guide rails (4), a pair of limit blocks (5), a pair of screw rods (6) and a motor, the two pairs of guide rails (4) are respectively installed on the left and right sides of the casting nozzle, a pair of limit blocks (5) are installed on the side of the guide rails away from the casting and rolling area, and the screw rod (6) passes through the limit blocks (5) to connect the motor and the connecting block (14) to control the coil box to move along the casting and rolling direction; the magnetic pulse generating unit consists of a pair of coil boxes (7 ), a middle coil (8), a side coil (9), an oil inlet (10), an oil outlet (11), a drainage line (12), a cover plate (13) and a connection block (14); a pulse power supply: a low-frequency pulse generator, a strong high-frequency pulse generator, and a brush; the current input method of the magnetic pulse generating casting and rolling nozzle is as follows: the casting and rolling nozzle is connected to the positive and negative poles of the external pulse power supply through the brush, the external current is input into the middle coil (8) and the side coil (9) through the brush, and the drainage line (12) is in direct contact with the middle coil (8) and the side coil (9) through the coil box (4).

[0006] Preferably, the nozzle upper plate, guide plate, and nozzle lower plate in the nozzle main body unit are all made of silicon nitride, combined with boron nitride coating, and bonded with high-temperature glue, and refractory mud is used to fill the gaps and trim the shape to form a wear-resistant and high-temperature resistant main structure.

[0007] Preferably, in the magnetic pulse generating unit, the coil box is made of a material with high magnetic permeability, so that the pulse electromagnetic field generated by the middle and side coils can act on the casting and rolling area quickly and accurately.

[0008] Preferably, in the magnetic pulse generating unit, the coil box is provided with a plurality of positioning grooves for placing the coils, so that the pulse electromagnetic field acts on the middle casting and rolling area and the edge casting and rolling area respectively, and fixes the coils. At the same time, the two groups of middle coils are connected to an external low-frequency pulse generator through drainage lines, and the edge coils are connected to an external strong-electric high-frequency pulse generator.

[0009] Preferably, in the magnetic pulse generating unit, the coil box is provided with oil inlet and oil outlet on both sides, so that the cooling oil fills the coil box to ensure rapid cooling of the coil winding, and the cooling oil can ensure that it does not explode when in contact with the magnesium alloy melt.

[0010] Preferably, in the magnetic pulse generating unit, the side coils are wound around the first positioning grooves on the left and right sides of the coil box, and the middle coils are wound around the six middle positioning grooves, so that the pulse electromagnetic field acts precisely on the sides and the middle.

[0011] Preferably, in the magnetic pulse generating unit, the cover plate is tightly connected to the groove on the surface of the coil box and the lower plate of the casting nozzle, and a high magnetic permeability material is selected to enable the pulse electromagnetic field to better act on the casting and rolling area.

[0012] Preferably, in the transmission unit, the coil boxes on the upper and lower sides of the nozzle body are connected by a connecting block, and the guide rail, the nozzle and the limit block are connected by screws, which is convenient for installation and disassembly.

[0013] The advantages and effects of the present invention are: 1. The present invention realizes the generation of an induced electromagnetic field at the entrance of the casting and rolling zone, forcing the melt at the entrance of the casting and rolling zone to circulate and generate Joule heat effect at the same time, which can promote nucleation at the solidification front, effectively refine the solidification structure, and reduce macro segregation; 2. In order to solve the problem that the temperature of the edge drops faster than that of the middle during the casting and rolling process, resulting in premature nucleation, the magnetic pulse generating unit under the casting nozzle can apply electromagnetic pulses to the middle and edge areas of the casting and rolling zone in different regions, so as to promote the temperature of the middle solidification zone to be close to that of the edge solidification zone, and to cause premature crystallization of the edge to fall off and nucleate at the same time as the middle area; at the same time, stronger induced Joule heat is generated at the edge of the casting and rolling zone to compensate for the heat dissipated by three-way heat exchange; 3. The magnetic pulse generating unit of the present invention drives the coil box through a motor, changes the position of the coil box to control the pulse electromagnetic field in the casting and rolling zone, and facilitates the installation and removal of the coil box; 4. The present invention realizes the use of pulsed electromagnetic field to adjust the temperature gradient of the solidification weld line, so that it changes from a ")" shape to a "1" shape, which can inhibit the casting and rolling edge cracks of magnesium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the working position and casting and rolling process of the present invention; Figure 2 It is an overall exploded view of the present invention; Figure 3 It is a top view and a right view of the present invention; Figure 4 An exploded view of a nozzle body of the present invention; Figure 5 It is a schematic diagram of a magnetic pulse generating unit of the present invention; Figure 6 An exploded view of the coil box of the present invention; Figure 7 It is a schematic diagram of the transmission unit of the present invention; Figure 8 This is a schematic diagram of the present invention controlling the shape of the solidification welding line from a ")" shape to a "1" shape; Among them: 1. Casting nozzle upper plate; 2. Guide plate; 3. Casting nozzle lower plate; 4. Guide rail; 5. Limit block; 6. Screw rod; 7. Coil box; 8. Middle coil; 9. Side coil; 10. Oil inlet; 11. Oil outlet; 12. Drain line; 13. Cover plate; 14. Connecting block. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Reference Figure 1-6 The present embodiment provides a magnetic pulse casting nozzle with solidification structure regulation function, the device comprises: the nozzle main body unit is composed of a nozzle upper plate (1), a guide plate (2), and a nozzle lower plate (3); the nozzle guide plate is fixed between the nozzle upper plate and the nozzle lower plate; the transmission unit is composed of two pairs of guide rails (4), a pair of limit blocks (5), a pair of screw rods (6) and a motor, the two pairs of guide rails (4) are respectively installed on the left and right sides of the casting nozzle, a pair of limit blocks (5) are installed on the side of the guide rail away from the casting and rolling area, the screw rod (6) passes through the limit block (5) to connect the motor and the connecting block (14), and controls the coil box to move along the casting and rolling direction; the magnetic pulse generating unit is composed of a pair of coil boxes (7 ), a middle coil (8), a side coil (9), an oil inlet (10), an oil outlet (11), a drainage line (12), a cover plate (13) and a connection block (14); a pulse power supply: a low-frequency pulse generator, a strong high-frequency pulse generator, and a brush; the current input method of the magnetic pulse generating casting and rolling nozzle is as follows: the casting and rolling nozzle is connected to the positive and negative poles of the external pulse power supply through the brush, the external current is input into the middle coil (8) and the side coil (9) through the brush, and the drainage line (12) is in direct contact with the middle coil (8) and the side coil (9) through the coil box (4).

[0017] To further optimize the solution, the nozzle upper plate, guide plate, and nozzle lower plate in the nozzle main unit are all made of silicon nitride, combined with boron nitride coating, and bonded with high-temperature glue, and refractory mud is used to fill the gaps and trim the shape to form a wear-resistant and high-temperature resistant main structure.

[0018] To further optimize the solution, in the magnetic pulse generating unit, the coil box is made of high magnetic permeability material so that the pulse electromagnetic field generated by the middle and side coils can act quickly and accurately on the casting and rolling area.

[0019] A further optimization scheme is that in the magnetic pulse generating unit, a plurality of positioning grooves for placing coils are provided in the coil box, so that the pulse electromagnetic field acts on the middle casting and rolling area and the edge casting and rolling area respectively, and fixes the coils. At the same time, the two groups of middle coils are connected to an external low-frequency pulse generator through drainage lines, and the edge coils are connected to an external strong-electric high-frequency pulse generator.

[0020] A further optimized solution is that in the magnetic pulse generating unit, oil inlets and oil outlets are opened on both sides of the coil box, so that cooling oil fills the coil box to ensure rapid cooling of the coil winding. The cooling oil can ensure that no explosion occurs when it comes into contact with the magnesium alloy melt.

[0021] According to a further optimization scheme, in the magnetic pulse generating unit, the edge coils are wound around the first positioning grooves on the left and right edges of the coil box, and the middle coils are wound around the six middle positioning grooves, so that the pulse electromagnetic field can act precisely on the edges and the middle.

[0022] To further optimize the solution, in the magnetic pulse generating unit, the cover plate is closely connected to the groove on the surface of the coil box and the lower plate of the casting nozzle, and a high magnetic permeability material is selected to enable the pulse electromagnetic field to better act on the casting and rolling area.

[0023] To further optimize the solution, in the transmission unit, the coil boxes on the upper and lower sides of the nozzle body are connected by a connecting block, and the guide rail, the nozzle and the limit block are connected by screws to facilitate installation and disassembly.

[0024] The implementation method includes the following steps: a. The molten magnesium alloy billet enters the casting nozzle through the circular hole on the upper plate of the casting nozzle and passes through the guide plate to the casting and rolling area for casting and rolling. The casting and rolling area model is as follows Figure 1 As shown; b. The motor drives the coil box to move close to the casting and rolling area, so that the pulse electromagnetic field generated by the middle coil and the side coil can act accurately on the solidification front of the casting and rolling; c. The middle coil 8 of the pulsed magnetic oscillation is connected to the positive and negative poles of the power supply through a brush, and the drain wire 12 contacts the middle coil 8. A pulse current with a specific waveform, frequency, duty cycle, and amplitude is passed through. The pulsed electromagnetic field formed forces the melt at the entrance of the casting and rolling zone to circulate and generate Joule heating effect at the same time, which can promote nucleation at the solidification front, effectively refine the solidification structure, and reduce macro segregation; d. The pulse magnetic oscillation edge coil 9 is fed with a specific high-frequency strong pulse current to generate a strong pulse electromagnetic field so that the edge of the casting and rolling zone receives a stronger Lorentz force, promoting premature crystallization and shedding of the edge and nucleation at the same time as the middle area; at the same time, a stronger induced Joule heat is generated at the edge of the casting and rolling zone to compensate for the heat dissipated by three-way heat exchange; e. The cooling oil circulates from the oil inlet 10 to the oil outlet 11, so that the cooling oil fills the coil box to ensure that the coil winding is cooled quickly without affecting its conductivity; f. The melt is subjected to electromagnetic force and Joule heat in the casting and rolling zone, and the solidification weld line changes from a ")" shape to a "1" shape, which can inhibit the casting and rolling edge cracks of the magnesium alloy.

[0025] Traditional casting and rolling can only change the position of the solidification weld line by changing the casting and rolling process parameters, but cannot change its shape. The present invention uses the Lorentz force and Joule heat generated by the pulsed electromagnetic field to adjust the shape of the solidification weld line to a "1" shape, so that the cooling and solidification rates in the width direction of the plate tend to be consistent, thereby achieving the purpose of suppressing the edge cracks of the magnesium alloy casting and rolling. At the same time, the melt is forced to oscillate, which promotes organizational homogenization and improves the segregation phenomenon of the cast and rolled plate. The pulsed electromagnetic field generates non-contact electromagnetic force on the melt, and also avoids the introduction of impurities. The yield rate and product performance of the magnesium alloy cast and rolled plate are improved.

Claims

1. A magnetic pulse casting nozzle with solidification structure regulation function, characterized in that: The nozzle main body unit is composed of a nozzle upper plate (1), a guide plate (2), and a nozzle lower plate (3); the nozzle guide plate is fixed between the nozzle upper plate and the nozzle lower plate; the transmission unit is composed of two pairs of guide rails (4), a pair of limit blocks (5), a pair of screw rods (6) and a motor; the two pairs of guide rails (4) are respectively installed on the left and right sides of the nozzle; a pair of limit blocks (5) are installed on the side of the guide rails away from the casting and rolling area; the screw rod (6) passes through the limit blocks (5) to connect the motor and the connection block (14) to control the coil box to move along the casting and rolling direction; the magnetic pulse generating unit is composed of a pair of coil boxes ( 7), a middle coil (8), a side coil (9), an oil inlet (10), an oil outlet (11), a drainage line (12), a cover plate (13) and a connection block (14); a pulse power supply: a low-frequency pulse generator, a strong high-frequency pulse generator, and a brush; the current input method of the magnetic pulse generating casting and rolling nozzle is as follows: the casting and rolling nozzle is connected to the positive and negative poles of the external pulse power supply through the brush, the external current is input into the middle coil (8) and the side coil (9) through the brush, and the drainage line (12) is in direct contact with the middle coil (8) and the side coil (9) through the coil box (4).

2. According to claim 1, a magnetic pulse casting nozzle with solidification structure regulation function, characterized in that: A plurality of positioning grooves for placing coils are reserved in the middle of the coil box (6), and the middle coil (7) and the side coil (8) can be wound around a suitable number of positioning grooves according to the casting and rolling conditions and environmental conditions.

3. According to claim 1, a magnetic pulse casting nozzle with solidification structure regulation function, characterized in that: The coil box (6) is provided with a drain wire (11) on the outside thereof, which contacts the middle coil (7) and the side coil (8) through the drain wire, wherein the side coil is connected to a strong high-frequency pulse generator, and the middle coil is connected to a low-frequency pulse generator. The pulse electromagnetic field generated by the coils makes the temperature of the middle and the side consistent, effectively improving the problem of uneven cooling of the side and the middle during casting and rolling.

4. According to claim 1, a magnetic pulse casting nozzle with solidification structure regulation function, characterized in that: Coil windings are evenly arranged above and below the casting nozzle near the entrance of the casting and rolling zone. The pulse electromagnetic field generated by the coil can accurately act on the front edge of the solidification welding line in the casting and rolling zone to achieve the effect of regulating the solidification structure.

5. According to claim 1, a magnetic pulse casting nozzle with solidification structure regulation function, characterized in that: An oil inlet (9) is provided on one side of the coil box exterior to allow cooling oil to quickly fill the coil box and quickly flow out from an oil outlet (10) on the other side, thereby quickly cooling the coil winding.

6. The casting and rolling nozzle with pulse magnetic oscillation effect according to claim 1, characterized in that: The pair of coil boxes (6) are connected by a pair of connecting blocks (14) and driven by a screw rod (6) and a motor, so that the coil boxes move above and below the casting nozzle along the casting direction. The motor drives the coil boxes and changes the position of the coil boxes to control the position of the pulse electromagnetic field in the casting zone, while facilitating the installation and removal of the coil boxes.

7. The casting and rolling nozzle with pulse magnetic oscillation effect according to claim 1, characterized in that: The nozzle guide plate (2) is fixed between the nozzle upper plate (1) and the nozzle lower plate (4). The nozzle upper plate is provided with a circular through hole to introduce the molten metal. The molten metal flows through the nozzle to the casting and rolling area. The nozzle body is tightly bonded by high-temperature glue and the gap is filled with refractory mud.

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