JP6967900B2 - Plasma generator and plasma torch - Google Patents

Description

The present invention relates to a plasma generator and a plasma torch.

Patent Document 1 discloses a plasma torch whose tip is made of graphite at least in order to control the temperature of a molten liquid metal (molten metal).

Japanese Unexamined Patent Publication No. 2001-033172

For example, in the conventional continuous casting apparatus, the ladle for storing the molten metal and the tundish arranged below the ladle for storing the molten metal supplied from the ladle have to be structurally close to each other. Therefore, in order to make the plasma torch reach the tundish while avoiding the ladle, it is necessary to arrange the plasma torch diagonally.

The form of the conventional plasma torch is generally a cylindrical shape. Therefore, when the plasma torch is arranged diagonally, the linear distance between the surface of the molten metal in the tundish and the plasma torch is minimized at the corner of the tip of the plasma torch. The shorter the linear distance from the surface of the molten metal in the tundish, the smaller the electrical resistance between the plasma torch and the molten metal, so that plasma is likely to be generated at the corners of the plasma torch.

On the other hand, the plasma torch is provided with a through hole that functions as a flow path for operating gas for generating plasma so as to extend in the length direction of the plasma torch. The higher the concentration of the operating gas, the easier it is for molecules or atoms to be ionized, so that plasma is more likely to be generated at the opening of the through hole, which is the outlet of the operating gas, in the plasma torch.

As described above, in the conventional plasma torch, there are a plurality of places where plasma is likely to be generated. Therefore, the plasma may move irregularly between the tip of the plasma torch and the surface of the molten metal due to a change in the concentration of the driving gas or the like. In this case, it may be difficult to control the temperature of the molten metal by plasma.

Therefore, an object of the present invention is to provide a plasma generator and a plasma torch capable of enhancing the stability of plasma.

The plasma generator according to one aspect of the present invention includes a plasma torch made of graphite having a straight rod shape, a holding tool for holding the plasma torch so that the plasma torch tilts at a predetermined angle with respect to the vertical axis, and the plasma torch. A supply means for supplying the operating gas for generating plasma to the plasma torch is provided, and the plasma torch is provided with a through hole that functions as a flow path for the operating gas supplied by the supply means so as to extend along the longitudinal direction. The tip of the plasma torch is provided and has a tapered shape, and the lowermost portion of the plasma torch is located near the peripheral edge of the through hole when viewed from the central axis direction of the plasma torch.

In the plasma generator according to one aspect of the present invention, the lowermost portion of the plasma torch is located near the peripheral edge of the through hole when viewed from the central axis direction of the plasma torch. Therefore, a region where the concentration of the operating gas increases between the plasma torch and the molten metal is generated below the lowermost portion of the plasma torch. That is, between the plasma torch and the molten metal, the region where the concentration of the operating gas is the highest (first region) and the region where the virtual straight line connecting the plasma torch (bottom) and the molten metal extends at the shortest (second region). Is almost the same as. In the first region, the electron density increases, so that plasma is likely to occur. In the second region, the electric resistance is small, so that dielectric breakdown is likely to occur, and the electron flow is likely to be concentrated at the bottom, so that plasma is likely to be generated. Therefore, according to the plasma generator according to one aspect of the present invention in which the first region and the second region substantially coincide with each other, it becomes difficult for the plasma to move irregularly, so that the stability of the plasma is improved. It will be possible to increase.

The plasma generator according to another aspect of the present invention includes a plasma torch made of graphite having a straight rod shape, a holding tool for holding the plasma torch so that the plasma torch tilts at a predetermined angle with respect to the vertical axis, and the plasma torch. The plasma torch is provided with a supply means for supplying an operating gas for generating plasma to the plasma torch, and the plasma torch has a first to Nth (however, N is 2) that functions as a flow path of the operating gas supplied by the supply means. The above natural number.) Is provided so as to extend along the longitudinal direction, the tip of the plasma torch has a tapered shape, and the bottom of the plasma torch is the nth when viewed from the central axis direction of the plasma torch. (However, n is a natural number of 1 to N.) When the position vector of the through hole is P _n and the flow rate of the operating gas discharged from the nth through hole is q _n , it is obtained by Equation 1. It is located near the end point of the position vector G.

In the plasma generator according to another aspect of the present invention, the lowermost portion of the plasma torch is located near the end point of the position vector G obtained by Equation 1 when viewed from the central axis direction of the plasma torch. The position vector G obtained by the equation 1 is a weighted average obtained by weighting the position vector of the through hole with the flow rate of the operating gas discharged from the through hole. That is, the end point of the position vector G is the point where the concentration of the operating gas discharged from each through hole is highest (so to speak, the concentration center of gravity of the operating gas). Therefore, a region where the concentration of the operating gas increases between the plasma torch and the molten metal is generated below the end point of the position vector G. That is, between the plasma torch and the molten metal, the region where the concentration of the operating gas is the highest (first region) and the region where the virtual straight line connecting the plasma torch (bottom) and the molten metal extends at the shortest (second region). Is almost the same as. In the first region, the electron density increases, so that plasma is likely to occur. In the second region, the electric resistance is small, so that dielectric breakdown is likely to occur, and the electron flow is likely to be concentrated at the bottom, so that plasma is likely to be generated. Therefore, according to the plasma generator according to another aspect of the present invention in which the first region and the second region substantially coincide with each other, it becomes difficult for the plasma to move irregularly, so that the stability of the plasma is improved. It will be possible to increase.

The plasma torch is located on and above the virtual conical surface with the bottom as the apex and the apex points downward, even if the angle between the virtual conical surface and the horizontal plane is 5 ° or more when viewed from the horizontal direction. good.

The plasma torch is located on and above the virtual V-shaped line with the lowest point as the apex when viewed from the horizontal direction and the apex points downward, and the angle between the virtual V-shaped line and the horizontal plane is 5 when viewed from the horizontal direction. It may be greater than or equal to °.

The plasma torch according to another aspect of the present invention has a straight rod shape and is made of graphite, and is provided with a through hole that functions as a flow path of an operating gas for generating plasma so as to extend along the longitudinal direction. The lowermost portion is located near the peripheral edge of the through hole when viewed from the central axis direction in a state where the tip portion has a tapered shape and is held so as to be tilted at a predetermined angle with respect to the vertical axis.

In the plasma torch according to another aspect of the present invention, the lowermost portion thereof is located near the peripheral edge of the through hole when viewed from the central axis direction. Therefore, when the plasma torch is installed above the molten metal, a region where the concentration of the operating gas increases between the plasma torch and the molten metal is generated below the lowermost portion of the plasma torch. That is, between the plasma torch and the molten metal, the region where the concentration of the operating gas is the highest (first region) and the region where the virtual straight line connecting the plasma torch (bottom) and the molten metal extends at the shortest (second region). Is almost the same as. In the first region, the electron density increases, so that plasma is likely to occur. In the second region, the electric resistance is small, so that dielectric breakdown is likely to occur, and the electron flow is likely to be concentrated at the bottom, so that plasma is likely to be generated. Therefore, according to the plasma torch according to another aspect of the present invention in which the first region and the second region substantially coincide with each other, the plasma is less likely to move irregularly, thereby enhancing the stability of the plasma. It becomes possible.

The plasma torch according to another aspect of the present invention has a straight rod shape and is made of graphite, and functions as a flow path of an operating gas for generating plasma. First to N (where N is a natural number of 2 or more). ) Is provided so as to extend along the longitudinal direction, the tip portion has a tapered shape, and is held so as to be tilted at a predetermined angle with respect to the vertical axis, when viewed from the central axis direction. When the position vector of the nth (where n is a natural number of 1 to N) through hole is P _n and the flow rate of the operating gas discharged from the nth through hole is q _n at the lowermost part. In addition, it is located near the end point of the position vector G obtained by Equation 2.

In the plasma torch according to another aspect of the present invention, the lowermost portion of the plasma torch is located near the end point of the position vector G obtained by the equation 1 when viewed from the central axis direction. The position vector G obtained by the equation 1 is a weighted average obtained by weighting the position vector of the through hole with the flow rate of the operating gas discharged from the through hole. That is, the end point of the position vector G is the point where the concentration of the operating gas discharged from each through hole is highest (so to speak, the concentration center of gravity of the operating gas). Therefore, when the plasma torch is installed above the molten metal, a region where the concentration of the operating gas increases between the plasma torch and the molten metal is generated below the end point of the position vector G. That is, between the plasma torch and the molten metal, the region where the concentration of the operating gas is the highest (first region) and the region where the virtual straight line connecting the plasma torch (bottom) and the molten metal extends at the shortest (second region). Is almost the same as. In the first region, the electron density increases, so that plasma is likely to occur. In the second region, the electric resistance is small, so that dielectric breakdown is likely to occur, and the electron flow is likely to be concentrated at the bottom, so that plasma is likely to be generated. Therefore, according to the plasma torch according to another aspect of the present invention in which the first region and the second region substantially coincide with each other, the plasma is less likely to move irregularly, thereby enhancing the stability of the plasma. It becomes possible.

In a state where the apex is held so as to be tilted at a predetermined angle with respect to the vertical axis, the apex is located on and above the virtual conical surface with the apex facing downward, and the virtual conical surface and the horizontal plane are The angle between the cones may be 5 ° or more when viewed from the horizontal direction.

The bottom is the apex when viewed from the horizontal direction, and the apex is located on and above the virtual V-shaped line facing downward, and the angle between the virtual V-shaped line and the horizontal plane is 5 ° or more when viewed from the horizontal direction. You may.

According to the plasma generator and plasma torch according to the present invention, it is possible to improve the stability of plasma.

FIG. 1 is a diagram showing one example of a continuous casting apparatus. FIG. 2A shows the connection state between the plasma torch and the operating gas source according to the first embodiment, and FIG. 2B shows the tip surface of the plasma torch of FIG. 2A. FIG. 3 shows a state of plasma generated between the plasma torch and the molten metal according to the first embodiment. FIG. 4 shows the state of plasma generated between the conventional plasma torch and the molten metal. FIG. 5A shows the connection state between the plasma torch according to the second embodiment and the operating gas source, and FIG. 5B shows the tip surface of the plasma torch according to the second embodiment. FIG. 6 shows the state of plasma generated between the plasma torch and the molten metal according to the second embodiment. FIG. 7A shows the connection state between the plasma torch according to the third embodiment and the operating gas source, and FIG. 7B shows the tip surface of the plasma torch according to the third embodiment. 8 (a) and 8 (b) show modified examples of the plasma torch 10 according to the second embodiment and the third embodiment, respectively. FIG. 9 shows another example of a plasma torch. The state of the plasma generated between the plasma torch and the molten metal according to the example of FIG. 9A is shown. FIG. 11 shows another example of a plasma torch. FIG. 12 shows another example of a plasma torch. FIG. 13 shows another example of a plasma torch.

As the embodiments according to the present disclosure described below are examples for explaining the present invention, the present invention should not be limited to the following contents. In the following description, the same code will be used for the same element or the element having the same function, and duplicate description will be omitted.

[First Embodiment]
First, the configuration of the continuous casting apparatus 100 will be described with reference to FIG. The continuous casting apparatus 100 includes a ladle 101, a tundish 102, a mold 103, a slab support roll 104, and a plasma generator 1.

The ladle 101 is a container for storing molten metal (molten steel) M. The tundish 102 is arranged below the ladle 101. The tundish 102 is a container for storing the molten metal M flowing out from the nozzle 101a provided on the bottom wall of the ladle 101. The mold 103 is located below the tundish 102. The mold 103 is formed into a predetermined shape while cooling the molten metal flowing out from the nozzle 102a provided on the bottom wall of the tundish 102. The slab support roll 104 conveys the slab S drawn from the mold 103 while cooling it.

The plasma generator 1 is a device for controlling the temperature of the molten metal M in the tundish 102. The plasma generator 1 includes a plasma torch 10, a torch holder 12, an elevator 14, and an operating gas source 16.

The plasma torch 10 is made of graphite, and is, for example, a round bar (straight bar) extending linearly. The diameter of the plasma torch 10 may be, for example, about 50 mm to 200 mm. The length of the plasma torch 10 may be, for example, about 1000 mm to 2500 mm. The shape of the plasma torch 10 may be a shape other than a round shape, or may not necessarily extend linearly but may be bent. The plasma torch 10 is connected to a power source (not shown), and a predetermined voltage (for example, about 100V to 500V) is applied.

As shown in FIG. 2, the plasma torch 10 is provided with a through hole H. The through hole H has a circular shape and is arranged on the central axis Ax of the plasma torch 10. That is, the through hole H extends along the longitudinal direction (central axis Ax) of the plasma torch 10. The diameter of the through hole H may be, for example, about 10 mm.

The tip portion T of the plasma torch 10 has a tapered shape whose diameter is reduced from the proximal end side toward the distal end side. Specifically, the tip portion T of the plasma torch 10 has a truncated cone shape. In FIG. 2, the diameter D1 of the tip surface 10a of the plasma torch 10 (tip portion T) is slightly larger than the diameter D2 of the through hole H. The size of the diameter D1 may be about 100% to 110% of the diameter D2. In this case, it can be said that the outer peripheral edge of the tip surface 10a is located near the peripheral edge of the through hole H. The size of the diameter D1 may be 56% or less of the diameter D3 of the base end portion B of the plasma torch 10. The angle formed by the generatrix of the tip portion T and the central axis Ax may be about 30 ° to 85 °.

Returning to FIG. 1, the torch holder 12 holds the upper end of the plasma torch 10. The torch holder 12 can hold the plasma torch 10 so that the plasma torch 10 is tilted by about 0 ° to 30 ° with respect to the vertical axis, for example. The elevator 14 raises and lowers the torch holder 12 in the vertical direction. Therefore, the plasma torch 10 held by the torch holder 12 is also moved up and down in the vertical direction by the elevator 14, and is brought close to and separated from the molten metal M in the tundish 102.

The plasma torch 10, which is held by the torch holder 12 so as to be tilted at a predetermined angle, has a lowermost (lowest point) LP, which is located at the lowest position, as shown in FIG. In the plasma torch 10 according to the first embodiment, the lowermost LP is a point on the outer peripheral edge of the tip surface 10a. The plasma torch 10 may be located on or above the virtual conical surface SF1 whose apex is the lowermost LP and the apex faces downward. The angle φ1 formed by the virtual conical surface SF1 and the horizontal plane SF2 may be 5 ° or more when viewed from the horizontal direction.

Returning to FIGS. 1 and 2, the operating gas source 16 supplies the operating gas (for example, an inert gas such as argon or nitrogen) for generating plasma to the through hole H. Therefore, the through hole H functions as a flow path for the operating gas. The operating gas source 16 is connected to the through hole H via the pipe 18. The pipe 18 is provided with a valve 20. According to the opening and closing of the valve 20, the supply state and the non-supply state of the operating gas from the operating gas source 16 to the through hole H are switched. In the first embodiment, the operating gas source 16, the pipe 18, and the valve 20 function as supply means for supplying the operating gas to the through hole H (plasma torch 10).

When plasma is generated by the plasma generator 1, first, the periphery of the tip portion T of the plasma torch 10 (near the surface of the molten metal M) is set as an operating gas atmosphere. Specifically, the valve 20 is opened to supply the operating gas from the operating gas source 16 to the through hole H.

Next, a predetermined voltage is applied to the plasma torch 10. Then, in this state, the plasma torch 10 is lowered toward the molten metal M by the elevator 14, and the distance (gap) between the plasma torch 10 and the molten metal M is brought close to a predetermined size. Then, dielectric breakdown occurs between the plasma torch 10 and the molten metal M, and a current flows between the plasma torch 10 and the molten metal M. As a result, as shown in FIG. 3, plasma P is generated between the plasma torch 10 and the molten metal M.

By the way, as shown in FIG. 4, the conventional graphite plasma torch 50 generally has a cylindrical shape. Therefore, due to the arrangement relationship between the ladle 101 and the tundish 102, if the plasma torch 50 is diagonally arranged toward the tundish 102 so as to avoid the ladle 101, the surface of the molten metal M in the tundish 102 and the plasma torch 50 are arranged. The minimum linear distance from the plasma torch 50 is the corner portion 50a at the tip of the plasma torch 50. The shorter the linear distance from the surface of the molten metal M in the tundish 102, the smaller the electric resistance between the plasma torch 50 and the molten metal M, so that plasma P1 is likely to be generated at the corner portion 50a of the plasma torch 50.

On the other hand, the plasma torch 50 is provided with a through hole 50b that functions as a flow path for operating gas for generating plasma so as to extend in the length direction of the plasma torch 50. As the concentration of the operating gas is higher, the molecules or atoms are more likely to be ionized, so that plasma P2 is more likely to be generated in the opening 50c of the through hole 50b which is the outlet of the operating gas in the plasma torch 50.

As described above, in the conventional plasma torch 50, there are a plurality of places where plasma is likely to be generated. Therefore, the plasmas P1 and P2 may move irregularly between the tip of the plasma torch 50 and the surface of the molten metal M due to a change in the concentration of the driving gas or the like. In this case, it may be difficult to control the temperature of the molten metal M by plasma.

However, in the first embodiment, the lowermost LP of the plasma torch 10 is located near the peripheral edge of the through hole H when viewed from the central axis Ax direction of the plasma torch 10. Therefore, a region where the concentration of the operating gas increases between the plasma torch 10 and the molten metal M is generated below the lowermost LP of the plasma torch 10. That is, between the plasma torch 10 and the molten metal M, the region where the concentration of the operating gas is the highest (first region) and the region where the virtual straight line connecting the plasma torch 10 (bottom LP) and the molten metal M extends at the shortest (the region). The second region) is substantially the same. In the first region, the electron density increases, so that plasma is likely to occur. In the second region, the electric resistance is small, so that dielectric breakdown is likely to occur, and the electron flow is likely to be concentrated at the bottom, so that plasma is likely to be generated. Therefore, according to the plasma generator 1 according to the first embodiment in which the first region and the second region substantially coincide with each other, it becomes difficult for the plasma to move irregularly, so that the stability of the plasma is improved. It becomes possible.

[Second Embodiment]
With reference to FIGS. 5 and 6, the plasma torch 10 according to the second embodiment will be described focusing on the differences from the plasma torch 10 according to the first embodiment.

As shown in FIG. 5, the plasma torch 10 may be provided with a plurality of through holes H1 to H4. Specifically, the through holes H1 to H4 have a circular shape and extend along the longitudinal direction of the plasma torch 10. The diameter of the through holes H1 to H4 may be, for example, about 10 mm. The through holes H1 to H4 are arranged on the same radius (same circumference) about the central axis Ax of the plasma torch 10. Distance between two adjacent through holes H1 to H4 (distance between through holes H1 and H2, distance between through holes H2 and H3, distance between through holes H3 and H4, and distance between through holes H4 and H1) Are almost the same.

The tip portion T of the plasma torch 10 has a conical shape. The plasma torch 10, which is held by the torch holder 12 so as to be tilted at a predetermined angle, has a lowermost (lowest point) LP, which is located at the lowest position, as shown in FIG. As shown in FIGS. 5 and 6, in the plasma torch 10 according to the second embodiment, the lowermost LP is the apex of the tip portion T and is located on the central axis Ax.

As shown in FIG. 5A, the operating gas source 16 supplies the operating gas to the through holes H1 to H4. Therefore, the through holes H1 to H4 function as a flow path for the operating gas. The operating gas source 16 is connected to the through holes H1 to H4 via the pipe 22, respectively. That is, the pipe 22 extends from the operating gas source 16 and then branches into four to reach the through holes H1 to H4. Valves 24 are provided at each of the four branch portions of the pipe 22. Depending on the opening and closing of the valve 24, the supply state and the non-supply state of the operating gas from the operating gas source 16 to the through holes H1 to H4 are switched. In the second embodiment, the operating gas source 16, the pipe 22, and the valve 24 function as supply means for supplying the operating gas to the through holes H1 to H4 (plasma torch 10).

When plasma is generated in the plasma torch 10 according to the second embodiment, each valve 20 is opened to supply operating gas from the operating gas source 16 to the through holes H1 to H4. As a result, the operating gas is simultaneously supplied to the through holes H1 to H4 at the same flow rate. Therefore, the region where the concentration of the operating gas increases between the plasma torch 10 and the molten metal M is generated at the center of the through holes H1 to H4 when viewed from the central axis Ax direction, that is, below the lowermost LP. In other words, when the central axis Ax direction viewed front end surface 10a side of the plasma torch 10, the origin of any point on the two-dimensional coordinates, respectively P ₁ position vector of each of the through holes H1-H4 to P When _4, the position vector G ₁ of the bottom LP can be expressed by equation 3.

Also in the second embodiment as described above, the region where the concentration of the operating gas is highest (first region) between the plasma torch 10 and the molten metal M, the plasma torch 10 (bottom LP), and the molten metal M are separated. It substantially coincides with the region (second region) where the virtual straight line connecting at the shortest extends. Therefore, it is possible to improve the stability of the plasma.

[Third Embodiment]
With reference to FIG. 7, the plasma torch 10 according to the third embodiment will be described focusing on the differences from the plasma torch 10 according to the second embodiment.

The plasma torch 10 according to the third embodiment is different from the plasma torch 10 according to the second embodiment in that the lowermost LP is not present on the central axis Ax. That is, in the plasma torch 10 according to the third embodiment, the lowermost LP is present at a position on the tip surface 10a different from the central axis Ax. The angle formed by the virtual plane SF3 orthogonal to the central axis Ax and the tip surface 10a is substantially the same at any location. For example, as shown in FIG. 7A, the angle θ1 formed by the virtual plane SF3 and the region of the tip surface 10a on the through hole H1 side, and the virtual plane SF3 and the tip surface 10a on the through hole H3 side. The angle θ2 formed by the region is substantially the same.

In the plasma torch 10 according to the third embodiment, the flow rates of the operating gas supplied from the operating gas source 16 to the through holes H1 to H4 are different. In the third embodiment, when the flow rate of the working gas in the respective through-holes H1~H4 and _q 1 to q _4, respectively, for _example, is set to _{q 1> q 2 = q 3} > q 4. Therefore, the region where the concentration of the operating gas increases between the plasma torch 10 and the molten metal M is generated at a position closer to the through hole H1 than the central axis Ax when viewed from the central axis Ax direction, that is, below the lowermost LP. In other words, when the central axis Ax direction viewed front end surface 10a side of the plasma torch 10, the origin of any point on the two-dimensional coordinates, respectively P ₁ position vector of each of the through holes H1-H4 to P _{If it is 4} , the position vector G ₂ of the lowest LP can be expressed by the equation 4.

Also in the third embodiment as described above, the region where the concentration of the operating gas is highest (first region) between the plasma torch 10 and the molten metal M, the plasma torch 10 (bottom LP), and the molten metal M are separated. It substantially coincides with the region (second region) where the virtual straight line connecting at the shortest extends. Therefore, it is possible to improve the stability of the plasma.

When the plasma torch 10 is provided with through holes of the first to Nth (where N is a natural number of 2 or more), the flow rate of the operating gas discharged from the nth through hole is q _n. Then, the position vector G of the lowest LP can be expressed by the general formula of the formula 5.

[Other embodiments]
Although the embodiments according to the present disclosure have been described in detail above, various modifications may be added to the above embodiments within the scope of the gist of the present invention. For example, the plasma torch 10 may function as an anode or a cathode. When the plasma torch 10 functions as an anode, electrons flow from the surface of the wide molten metal M toward the bottom LP of the plasma torch 10 so as to converge, so that the plasma is usually liable to become unstable. However, according to the plasma generator 1 according to the above embodiment, the region where the concentration of the operating gas is the highest (first region) between the plasma torch 10 and the molten metal M and the plasma torch 10 (bottom LP). Since the region (second region) where the virtual straight line connecting the molten metal M and the molten metal M extends at the shortest, it is possible to improve the stability of the plasma even when the plasma torch 10 functions as an anode. Become.

As shown in FIG. 8, the angle formed by the virtual plane SF3 orthogonal to the central axis Ax and the tip surface 10a does not have to be substantially the same at any location. For example, (a) and (b) of FIG. 8 are modified examples of the plasma torch 10 according to the second embodiment and the third embodiment, respectively, and are a region of the virtual plane SF3 and the tip surface 10a on the through hole H1 side. The angle θ1 formed by the torch and the angle θ2 formed by the virtual plane SF3 and the region of the tip surface 10a on the through hole H3 side are different (θ1 <θ2).

As shown in FIG. 9, the plasma torch 10 may have a shape in which the tip end portion of the cylinder is cut off by a predetermined plane. FIG. 9A shows an example in which the lowermost LP is located on the central axis Ax. FIG. 9B shows an example in which the lowermost LP is not located on the central axis Ax (an example in which the lowermost LP is located at a position different from the central axis Ax in the tip surface 10a). In other words, (a) and (b) of FIG. 9 show a case where the angle θ2 is 0 ° in the plasma torch 10 shown in FIGS. 8 (a) and 8 (b), respectively.

FIG. 10 shows how the plasma torch 10 as shown in FIG. 9 is held by the torch holder 12 so as to be tilted at a predetermined angle. In the plasma torch 10 according to this example, the lowermost LP is a line of intersection where the tip surface 10a and the plane from which the tip surface 10a is cut off intersect. The plasma torch 10 may be located on or above the virtual V-shaped line VL having the lowermost LP as an apex and the apex facing downward. The angle φ2 formed by the virtual V-shaped line VL and the horizontal plane SF2 may be 5 ° or more when viewed from the horizontal direction.

As shown in FIG. 11, the lowermost portion of the plasma torch 10 may be located on or near the peripheral edge of the through hole. FIG. 11A shows an example in which the through hole H5 is further provided on the central axis Ax in the plasma torch 10 of the second embodiment. FIG. 11B shows an example in which the through hole H1 is provided so as to pass through the apex of the tip portion T in the plasma torch 10 according to the third embodiment. 11 (c) shows an example in which the through hole H5 is further provided on the central axis Ax in the plasma torch 10 of FIG. 9 (a).

As shown in FIG. 12, the central portion may protrude outward from the outer peripheral portion of the plasma torch 10. FIG. 12A shows an example in which the through hole H5 portion protrudes from the outer peripheral portion of the plasma torch 10 of FIG. 11A. FIG. 12B shows an example in which the plasma torch 10 of FIG. 12A has a recessed portion 10b at the tip of the central portion instead of the presence of the through hole H5.

As shown in FIG. 13, the outer shape of the plasma torch 10 may be other than the circular shape. FIG. 13A shows an example of a shape in which a part of a circle is cut off. FIG. 13B shows a triangular example. FIG. 13 (c) shows an example of a quadrangular shape. In FIG. 13D, one corner of the quadrangle is rounded (R chamfered) and another corner is linearly cut out (C chamfered). Yes) Here is an example.

The plasma torch 10 may be formed by arbitrarily combining various modifications described above.

1 ... Plasma generator, 10 ... Plasma torch, 10a ... Tip surface, 12 ... Torch holder, 14 ... Elevator, 16 ... Operating gas source (supply means), 18 ... Piping (supply means), 20, 24 ... Valve ( Supply means), 22 ... piping, 100 ... continuous casting equipment, 101 ... ladle, 102 ... tundish, 103 ... mold, 104 ... slab support roll, Ax ... central shaft, D1 to D3 ... diameter, H, H1 to H4 ... through hole, LP ... bottom, M ... molten metal (molten steel), P1, P2 ... plasma, S ... slab, SF1 ... virtual conical surface, SF2 ... horizontal plane, SF3 ... virtual plane, T ... tip, VL ... Virtual V-shaped line, φ1, φ2, θ1, θ2 ... Angle.

Claims (8)

A graphite plasma torch that has a straight rod shape,
A holder that holds the plasma torch so that the plasma torch tilts at a predetermined angle with respect to the vertical axis.
A supply means for supplying an operating gas for generating plasma to the plasma torch is provided.
The plasma torch is provided with a through hole that functions as a flow path for the operating gas supplied by the supply means so as to extend along the longitudinal direction.
The tip of the plasma torch has a tapered shape and has a tapered shape.
A plasma generator in which the lowermost portion of the plasma torch is located near the peripheral edge of the through hole when viewed from the central axis direction of the plasma torch. A graphite plasma torch that has a straight rod shape,
A holder that holds the plasma torch so that the plasma torch tilts at a predetermined angle with respect to the vertical axis.
A supply means for supplying an operating gas for generating plasma to the plasma torch is provided.
The plasma torch is provided with through holes of the first to Nth (however, N is a natural number of 2 or more) that functions as a flow path of the operating gas supplied by the supply means so as to extend along the longitudinal direction. Be,
The tip of the plasma torch has a tapered shape and has a tapered shape.
When viewed from the central axis direction of the plasma torch, the lowermost portion of the plasma torch has the position vector of the nth (where n is a natural number of 1 to N) through hole as P _n, and the nth penetration. A plasma generator located near the end point of the position vector G obtained by Equation 1 when the flow rate of the operating gas discharged from the hole is q _n.

The plasma torch is located on and above a virtual conical surface having the lowest portion as an apex and the apex facing downward.
The plasma generator according to claim 1 or 2, wherein the angle formed by the virtual conical surface and the horizontal plane is 5 ° or more when viewed from the horizontal direction. The plasma torch is located on and above the virtual V-shaped line whose apex is the lowest point when viewed from the horizontal direction and whose apex faces downward.
The plasma generator according to claim 1 or 2, wherein the angle formed by the virtual V-shaped line and the horizontal plane is 5 ° or more when viewed from the horizontal direction. It has a straight rod shape and is made of graphite.
A through hole that functions as a flow path for operating gas for generating plasma is provided so as to extend along the longitudinal direction.
The tip has a tapered shape,
A plasma torch in which the lowermost portion is located near the peripheral edge of the through hole when viewed from the central axis direction in a state where the torch is held so as to be tilted at a predetermined angle with respect to the vertical axis. It has a straight rod shape and is made of graphite.
Through holes of the first to Nth (where N is a natural number of 2 or more) that functions as a flow path for operating gas for generating plasma are provided so as to extend along the longitudinal direction.
The tip has a tapered shape,
In a state where the hole is held so as to be tilted at a predetermined angle with respect to the vertical axis, the lowermost portion thereof is the nth (where n is a natural number 1 to N) through hole when viewed from the central axis direction. A plasma torch located near the end point of the position vector G obtained by Equation 2 when the position vector is P _n and the flow rate of the operating gas discharged from the nth through hole is q _n.

In a state where the apex is held so as to be tilted at a predetermined angle with respect to the vertical axis, the apex is located on and above the virtual conical surface facing downward.
The plasma torch according to claim 5 or 6, wherein the angle formed by the virtual conical surface and the horizontal plane is 5 ° or more when viewed from the horizontal direction. When viewed from the horizontal direction, the apex is the apex, and the apex is located on and above the virtual V-shaped line facing downward.
The plasma torch according to claim 5 or 6, wherein the angle formed by the virtual V-shaped line and the horizontal plane is 5 ° or more when viewed from the horizontal direction.

Images