JP7261199B2 - Powder manufacturing equipment - Google Patents

Description

The present invention relates to a powder manufacturing apparatus using a plasma rotating electrode method.

Metal powders are used in such applications as thermal spraying of special alloys, coatings, artificial joints and the manufacture of 3D printers. As such a powder manufacturing apparatus, Patent Document 1 discloses a powder manufacturing apparatus using a plasma rotating electrode method. In the plasma rotating electrode method, a metal rod that is rotated at high speed is melted by a plasma arc. It is a method of producing a spherical powder by solidifying to a solid. Patent Literature 2 discloses a device for rotating a metal rod used in a powder manufacturing apparatus.

Japanese Utility Model Laid-Open No. 4-097814 Japanese Patent Application Laid-Open No. 2001-240903

In conventional powder applications, a particle size of about 150 μm was sufficient, but with the recent technological development of 3D printers, further reduction in the particle size of the powder is required. For example, powder used in a powder head type 3D printer is required to have a particle size of about 50 μm. The particle size of the powder produced by the plasma rotating electrode method changes according to the magnitude of the centrifugal force acting on the metal rod, and the magnitude of the centrifugal force can be adjusted by changing the diameter and rotation speed of the metal rod. It is possible. When producing powder with a particle size of 150 μm, the desired particle size can be obtained, for example, by rotating a metal rod with a diameter of 50 mm at 20000 rpm. metal rod must be rotated at 40000 rpm.

As described above, it is necessary to increase the diameter of the metal rod and further increase the rotational speed in order to cope with the reduction in the diameter of the powder. It was not possible to rotate the metal rod at such a rotational speed. For example, in the devices disclosed in Patent Documents 1 and 2, power is supplied to the metal rod by bringing a power supply brush into contact with the spindle. However, when the power supply brush is used, a frictional force is generated between the spindle and the power supply brush when the metal rod rotates, and a force that inhibits rotation acts. This is a factor that prevents the metal rod from rotating at a higher speed.

In addition, in the power supply structure where the power supply part and the spindle are in contact like the structure using the conventional power supply brush, the more the rotation speed increases, the more the frictional heat between the power supply part and the spindle increases. It was necessary to increase the capacity of the cooling device that performs However, there are restrictions on the improvement of the cooling capacity from the viewpoint of increasing the size of the device and increasing the cost for securing the cooling capacity, and the maximum speed of the rotation speed has been limited. In addition, the power supply brush is pressed against the spindle by a plurality of springs, which becomes a source of vibration (resonance) of the spindle as the rotation speed increases, which is also one of the obstacles to speeding up. Furthermore, as the diameter of the metal rod increases, a heat source that uniformly melts the molten surface is also required. In this way, the conventional powder production equipment was unable to cope with even higher rotation speeds of metal rods and a uniform heat source for melting. Body manufacturing equipment is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to enable high-speed rotation of a metal rod in a powder manufacturing apparatus.

The present invention for solving the above-mentioned problems is a powder manufacturing apparatus comprising: a chamber in which a metal rod is melted; a rotating body to which the metal rod is attached at an end in the axial direction; and a tip surface of the metal rod. a melting torch that irradiates an arc to the melting torch; Further, it is characterized in that it is arranged at a position where current can be passed through the metal rod and the arc.

High-speed rotation of the metal rod becomes possible in the powder manufacturing apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the powder manufacturing apparatus which concerns on embodiment of this invention. 2 is a diagram showing a schematic configuration around a spindle of the powder manufacturing apparatus of FIG. 1; FIG. It is a figure which shows the example of an electric power feeding structure. In this figure, the metal rod is indicated by a two-dot chain line. It is a figure which shows the example of an electric power feeding structure. FIG. 5 is a view for explaining the disposition of the melting torch in FIG. 4, and is a view of the melting torch seen from the tip side. FIG. 4 is a diagram for explaining forces acting on a plasma arc when there is no magnetic force generator; FIG. 4 is a diagram for explaining forces acting on a plasma arc when there is a magnetic force generator; FIG. 4 is a diagram showing an example of a melting arc irradiation position; This figure shows the state of the molten surface of the metal rod and the shape of the dent in each example. It is a figure which shows the example of an electric power feeding structure. It is a figure which shows the example of an electric power feeding structure. It is a figure which shows the example of an electric power feeding structure. FIG. 12 is a view for explaining the disposition of the melting torch and the feeding torch in FIG. 11, and is a view of each torch as viewed from the tip side. 12 is an enlarged view of the tip of the melting torch of FIG. 11; FIG. It is a figure which shows the example of an electric power feeding structure. FIG. 15 is a view for explaining the disposition of the melting torch and the feeding torch in FIG. 14, and is a view of each torch as seen from the tip side.

An embodiment of the present invention will be described below with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

As shown in FIGS. 1 to 3, the powder production apparatus 1 of the present embodiment includes a chamber 10 in which the metal rod 2 is melted, a rotating body 20 that supports the metal rod 2, and a tip surface of the metal rod 2. A melting torch 30 for irradiating arc to 2a and a power feeding torch 40 which is an example of a power feeding electrode arranged near the metal rod 2 are provided. The type of melting torch 30 is not particularly limited, and may be, for example, a plasma torch or a TIG torch. Further, the type of power feeding electrode is not particularly limited, and may be, for example, a plasma torch or a water-cooled electrode.

The chamber 10 is a vertically extending cylindrical container. A gas supply pipe 11 and a gas exhaust pipe 12 are connected to the chamber 10 . The gas supply pipe 11 is connected to a gas supply source (not shown) and supplies atmospheric gas to the interior of the chamber 10 . Atmosphere gas is gas, such as argon, helium, and nitrogen, for example. The gas exhaust pipe 12 is connected to a vacuum pump 13, and the melting treatment of the metal rod 2 is performed in a state in which the chamber is evacuated by the vacuum pump 13 and then filled with atmospheric gas. The lower end of the chamber 10 is funnel-shaped, and the produced powder is recovered from the lower end of the chamber 10 . The shape of the chamber 10, the connection positions of the pipes, and the like are not limited to the configuration described in the present embodiment, and may be any configuration that enables powder production by the plasma rotating electrode method.

The rotating body 20 is a structure that transmits the rotational force of the drive source 14 (for example, a motor) to the metal rod 2 , and the metal rod 2 is attached to the axial direction A end of the rotating body 20 . The powder production apparatus 1 of this embodiment includes a rotating body housing chamber 50 that houses a rotating body 20 , and the rotating body 20 is arranged inside the rotating body housing chamber 50 . The rotor housing chamber 50 communicates with the space inside the chamber 10 , and the atmosphere inside the rotor housing chamber 50 is the same as the atmosphere inside the chamber 10 . The chamber 10 and the rotating body housing chamber 50 have a sealed structure to prevent the atmosphere from entering or exiting from the outside, and a sealing material (not shown) is provided in the gaps between the connection points of various parts. is provided.

The rotating body 20 has a spindle 21 and a metal rod holder 22 . The metal rod holder 22 is provided at the end of the spindle 21 on the metal rod mounting side. The metal rod holder 22 has a structure to which the metal rod 2 can be fixed and to which the metal rod 2 can be detachably attached. It should be noted that the rotating body 20 is not limited to the structure described in the present embodiment, and other components may be provided between the drive shaft 15 connected to the drive source 14 and the metal rod 2, for example.

A magnetic coupling 60 is provided at the end of the spindle 21 on the drive source side. The magnet coupling 60 connects the drive shaft 15 connected to the drive source 14 and the spindle 21 . The magnet coupling 60 has a spindle side part 61 and a drive shaft side part 62, and both parts are arranged with a wall portion 51 of the rotating body housing chamber 50 on the drive source 14 side sandwiched therebetween. That is, the spindle side component 61 is arranged inside the rotating body accommodating chamber 50 , and the drive shaft side component 62 is arranged outside the rotating body accommodating chamber 50 . Rotational power is transmitted by magnetism between the spindle side part 61 and the drive shaft side part 62 arranged in this way.

A static pressure gas bearing (gas bearing) 70 is provided as a bearing for supporting the spindle 21 inside the rotating body housing chamber 50 . The static pressure gas bearing 70 is a bearing that uses gas as a working fluid, and the static pressure gas bearing 70 is provided with a supply port (not shown) for supplying the working fluid. The supplied gas is preferably the same gas as the atmosphere gas in the chamber 10, and argon gas is supplied in the example of FIG. The static pressure gas bearing 70 of this embodiment is arranged inside the rotating body housing chamber 50 . The number of static pressure gas bearings 70 is not particularly limited, and is appropriately changed according to the length of spindle 21 . By using the hydrostatic gas bearing 70 as a bearing that supports the spindle 21, the contact resistance during rotation of the rotating body 20 can be reduced as compared with the case of using a ball bearing. Therefore, it is preferable to use the static pressure gas bearing 70 as a bearing for supporting the spindle 21 from the viewpoint of achieving a higher rotation speed of the metal.

Note that the rotating body housing chamber 50 may have a structure that does not communicate with the atmosphere inside the chamber 10 . Also, the coupling may have a structure in which the drive shaft 15 and the spindle 21 are mechanically fastened. Even with such a structure, the metal rod 2 can be rotated at a high speed according to the powder manufacturing apparatus 1 capable of non-contact power supply to the metal rod 2, which will be described later. The main purpose of this device is to produce fine powder of 50 μm for 3D printers, for example. do. In order to increase the rotational speed of the metal rod 2, the diameter of the spindle 21 must be increased. , and there may be concerns in terms of parts procurement. On the other hand, according to the structure provided with the rotating body housing chamber 50 and the static pressure gas bearing 70 as in the present embodiment, the rotational frictional resistance can be extremely reduced because the spindle 21 is floating on the gas. Therefore, the above concerns do not arise. In addition, according to the structure in which the rotating body housing chamber 50 and the magnetic coupling 60 are provided, as in the present embodiment, since rotational power is transmitted to the rotating body 20 via the magnetic coupling 60, the rotating body 20 is Since it does not penetrate the rotating body housing chamber 50 (chamber 10), it is not necessary to use a sealing material to prevent the inflow of the external atmosphere. Therefore, since there is no seal resistance when the rotor 20 rotates, the rotational speed of the rotor 20 can be easily increased. That is, from the viewpoint of further increasing the speed of rotation of the metal rod 2, it is preferable to provide the rotating body housing chamber 50 and the magnet coupling 60. FIG.

A melting torch 30 for irradiating the metal rod 2 with a plasma arc is arranged at a position facing the tip end surface 2 a of the metal rod 2 so that the tip thereof faces the tip end surface 2 a of the metal rod 2 . In the example of FIG. 3, the center of the melting torch 30 (the center of the hole of the plasma gas outlet) and the rotation center C of the metal rod 2 do not match. If the melting torch 30 is displaced by an appropriate amount in the radial direction with respect to the center of rotation C of the metal rod 2, the tip end surface 2a of the metal rod 2 can be formed into an ideal mortar-like concave shape. . Since the metal rod 2 and the rotating body 20 rotate coaxially, "the position facing the tip surface 2a of the metal rod 2" can be rephrased as "the position facing the end surface 20a of the rotating body 20 on the metal rod mounting side". be able to. Further, in the following description, "rotating direction R of rotating body 20" and "rotating center C of rotating body 20" may be described, but these descriptions are referred to as "rotating direction of metal rod 2" and "metal rod 2 It is synonymous with "the center of rotation of".

The melting torch 30 penetrates the side of the chamber 10 , and a sealing material (not shown) is provided between the chamber 10 and the melting torch 30 . The melting torch 30 is installed in a horizontally movable state, and the melting torch 30 can be horizontally moved according to the amount of the metal rod 2 to be melted. The melting torch 30 of this embodiment is a plasma torch. Since the plasma torch has been known for a long time, a detailed description of the structure of the plasma torch is omitted. The power supply torch 40 is arranged in the vicinity of the metal rod 2 at a position where it does not come into contact with the metal rod 2 and can be energized through the metal rod 2 and the arc.

(Power supply structure example 1)
In the power supply structure shown in FIG. 3, the power supply torch 40 is arranged at a position facing the outer peripheral surface 2b of the metal rod 2. As shown in FIG. In the example of FIG. 3 , the tip 40 a of the power supply torch 40 faces the outer peripheral surface 2 b of the metal rod 2 attached to the rotating body 20 . The power supply torch 40 of this embodiment is an electrode rod made of a metal material (for example, copper). The power supply torch 40 has a structure in which cooling water circulates inside. Although not shown, six power supply torches 40 are provided at equal intervals along the rotation direction R of the rotor 20 . Therefore, when the six power feeding torches 40 are viewed from the axial direction A of the rotating body 20 (that is, the axial direction of the metal rod 2), the tip 40a of each power feeding torch 40 is located at the rotation center C of the rotating body 20. It is in a state suitable for

In this embodiment, the melting torch 30 arranged as described above is connected to the cathode side of the plasma power source 16 , and the power supply torch 40 is connected to the anode side of the plasma power source 16 . That is, the melting torch 30 and the feeding torch 40 have different polarities when energized. In this specification, the torch connected to the anode side of the plasma power source 16 is called "anode torch", and the torch connected to the cathode side of the plasma power source 16 is called "cathode torch". In addition, when the anode torch is a plasma torch, it is referred to as "anode plasma torch", when the cathode torch is a plasma torch, it is referred to as "cathode plasma torch", and when the anode is a water-cooled copper electrode, it is referred to as "anode torch". ”. In the case of the feeding structure of FIG. 3, the melting torch 30 is a cathode plasma torch and the feeding torch 40 is an anode torch.

When energizing with the power supply structure illustrated in FIG. 3, the melting torch 30 first ignites a pilot arc (arc between the tungsten rod and the tip) (not shown) and ejects high temperature (plasma) argon gas from the tip outlet. Let In this state, when a high voltage and high frequency for ignition (not shown) is applied between the tungsten rod of the melting torch 30 and the power feeding torch 40, a plasma arc is generated between the melting torch 30 and the metal rod 2, and the power feeding torch 40 and the metal An arc is generated between the bars 2 . In other words, a current flows between the power supply torch 40, the metal rod 2, and the melting torch 30. FIG. As a result, the plasma arc is irradiated from the melting torch 30 toward the tip surface 2a of the metal rod 2, and melting of the tip surface 2a of the metal rod 2 is started. Then, the molten liquid metal is moved to the outer peripheral end of the tip surface 2a by the centrifugal force caused by the rotation of the metal rod 2 and scatters as droplets to produce powder. In the powder manufacturing apparatus 1 having the power feeding structure as in this embodiment, powder can be manufactured in a state in which the power feeding torch 40 is not in contact with the metal rod 2 . That is, since there is no contact resistance between the metal rod 2 and the power supply torch 40 when the metal rod 2 is rotated, no force is generated to hinder the rotation of the metal rod 2, and the rotation speed can be improved. Furthermore, since no friction occurs between the power supply portion and the metal rod 2, a cooling mechanism for cooling the heat generating portion due to friction becomes unnecessary, and the structure of the powder production apparatus 1 can be simplified.

When the magnetic coupling 60 is used to connect the drive shaft 15 and the rotating body 20, if the power supply unit and the magnetic coupling 60 are located close to each other, the magnetic field generated at the power supply unit adversely affects the operation of the magnetic coupling 60. things can happen. On the other hand, according to the powder manufacturing apparatus 1 of the present embodiment, since the power supply section and the magnetic coupling 60 are arranged at a distance, the performance of the magnetic coupling 60 can be maximized. Further, when the magnetic coupling 60 is used, for example, when a conventional ball bearing is used, if there is a relatively large contact resistance between the spindle 21 and the ball bearing, the drive source 14 is driven to increase the rotation speed of the rotating body 20 . When the output of is increased, the spindle side part 61 of the magnet coupling 60 is affected by the above contact resistance, and rotational speed deviation occurs between the drive shaft side part 62 and the spindle side part 61 of the magnet coupling 60 . On the other hand, in the powder production apparatus 1 of the present embodiment, the static pressure gas bearing 70 is used to support the spindle 21, so the contact resistance of the spindle 21 can be suppressed. As a result, it is possible to suppress rotational deviation between the spindle-side component 61 and the drive-shaft-side component 62 of the magnetic coupling 60 . That is, the magnetic coupling 60 can exhibit maximum performance by combining the contactless power supply structure for the metal rod 2 as in the present embodiment and the static pressure gas bearing 70 . Therefore, according to the powder production apparatus 1 in which the contactless power supply structure to the metal rod 2, the magnetic coupling 60 and the static pressure gas bearing 70 are combined as in the present embodiment, the metal rod 2 can be rotated at a higher speed. It becomes possible.

Furthermore, in the power supply structure of FIG. 3, an arc is also generated between the power supply torch 40 and the metal rod 2, and the heat generated here can be used as energy for melting the metal rod 2. Therefore, it is possible to increase the amount of metal rods 2 dissolved per unit time, and to increase the efficiency of powder production. In the power supply structure of FIG. 3, six power supply torches 40 are provided along the rotation direction R of the metal rod 2, but the number of the power supply torches 40 is not particularly limited, and a desired amount per unit time can be obtained. is appropriately changed according to the amount of powder production. Further, the heat load on the tip of the electrode of the power feeding torch 40 can be reduced by reducing the arc current per power feeding torch 40, and the life of the power feeding torch 40 can be extended. The installation position of the power feeding torch 40 in the axial direction A of the metal rod 2 is not particularly limited, but when a plurality of power feeding torches 40 are provided, each power feeding torch 40 is positioned in the axial direction A of the metal rod 2. may be arranged at a certain distance from each other. Furthermore, the power supply torch 40 may move synchronously with the melting torch 30 when the melting torch 30 moves along the axial direction A of the metal rod 2 .

Although the structure of FIG. 3 (power supply structure example 1) has been described as the power supply structure in the above description, the power supply structure is not limited to the structure shown in FIG. Examples 2 to 6 of the power supply structure will be described below as other examples of the power supply structure. In the drawings referred to in the following description, dashed arrows indicate the direction of the current, and curved solid arrows indicate the direction of the magnetic field generated by the flow of the current.

(Power supply structure example 2)
4 and 5, the melting torch 30 is a cathode plasma torch and the feeding torch 40 is an anode torch. A plurality of melting torches 30 of this power supply structure are provided, and the respective melting torches 30 are arranged so as to be parallel to each other. Further, as shown in FIG. 5, the melting torches 30 are arranged side by side along the rotation direction R of the rotor 20 when viewed from the axial direction A of the rotor 20 . The power feeding torch 40 is arranged in the same manner as the power feeding structure of FIG.

In this power supply structure, a magnetic force generator 80 is provided outside the melting torch 30 . In other words, the melting torch 30 is arranged between the rotation center C of the rotor 20 and the magnetic force generator 80 . When the metal rod 2 is melted, an arc current flows between the melting torch 30 and the metal rod 2. The magnetic force generator 80 generates a magnetic force to offset the Lorentz force F generated by the arc current. It is.

In the example of FIG. 4, the magnetic force generator 80 has an L-shaped conductor 81 made of a metal material (for example, copper), and the conductor 81 has a structure in which cooling water circulates. The conductor 81 has a parallel portion 82 extending parallel to the melting torch 30 and an inclined portion 83 extending outward from the melting torch 30 from an end portion 82 a of the parallel portion 82 on the rotor side. An end portion 82 a of the parallel portion 82 on the rotating body side is positioned closer to the rotating body 20 than the tip portion 30 a of the melting torch 30 . A parallel portion 82 of the conductor 81 is connected to the cathode side of the plasma power source 16 , and an inclined portion 83 of the conductor 81 is electrically connected to the melting torch 30 . In the case of such a power supply structure, the arc current flowing between the melting torch 30 and the metal rod 2 and the current flowing through the parallel portion 82 of the conductor 81 are in the same direction, and the parallel portion of the melting torch 30 and the conductor 81 At 82, parallel current flows.

When a plurality of melting torches 30 are arranged parallel to each other, the current of the melting arc 31 becomes a parallel current, and the melting arc 31 irradiated from each melting torch 30 is generated by the current. A Lorentz force F that attracts each other under the influence of the magnetic field acts. In the example of FIG. 6, a magnetic field is generated between two parallel melting arcs 31 as shown in FIG. The outer magnetic flux is in a strong state, and the Lorentz force F works in the current direction of this outward magnetic flux and the melting arc 31, and the respective melting arcs 31 attract each other as shown in FIG. Therefore, in the power supply structure without the magnetic force generator 80, the melting arc 31 emitted from each melting torch 30 is shifted toward the central portion of the tip surface 2a of the metal rod 2 as shown in FIG. Such a phenomenon that the irradiation position of the plasma arc changes due to the arc current flowing between the melting torch 30 and the metal rod 2 is called "magnetic blow". Although it is possible to rotate the metal rod 2 at a high speed even when magnetic blow occurs, it is preferable to suppress the magnetic blow from the viewpoint of uniformly melting the tip surface 2a of the metal rod 2.

If the magnetic force generator 80 is provided as shown in FIG. 7, the melting arc 31 irradiated from the melting torch 30 is affected by the magnetic field generated by the current flowing through the parallel portion 82 of the conductor 81, and the conductor A Lorentz force F _J that attracts to the 81 side is generated. Since the Lorentz force _FJ generated here is a force in the opposite direction to the Lorentz force F generated between the melting arcs 31, these Lorentz forces F and _FJ cancel each other. As a result, the magnetic flux balance around the melting arc 31 in the circumferential direction is balanced, magnetic blow can be suppressed, and the desired position of the metal rod 2 can be irradiated with the plasma arc. The distance between the parallel portion 82 of the conductor 81 and the melting arc 31 is preferably the same as the distance between the melting arcs 31. You can change it.

Although one magnetic force generator 80 is provided for one melting torch 30 in the example of FIG. to be changed accordingly. Moreover, although the conductor 81 of the magnetic force generator 80 in this power supply structure is L-shaped, the shape of the conductor 81 is not particularly limited as long as it has the parallel portion 82 . Moreover, the structure of the magnetic force generator 80 is not limited to the structure described in the example of FIG.

Furthermore, as an important effect in the examples of FIGS. 4 to 7, "By melting the tip surface 2a of the metal rod 2 with a plurality of melting torches 30, the surface of the tip surface 2a of the metal rod 2 having a large diameter can be can be made a more uniform melting surface”. As a result, the melting surface of the metal rod 2 can be formed into an ideal mortar-shaped concave shape, making it possible to produce finer and more uniform particle size powder.

A preferable irradiation position of the melting arc 31 for obtaining a uniform melting surface as described above will be described with reference to FIG. FIG. 8 is a diagram showing the difference in the state of the melting surface 90 and the recess shape 91 when the number and arrangement of the melting torches 30 are different. It should be noted that illustration of the melting torch 30 is omitted in FIGS. 8(b) to 8(d).

FIG. 8(a) shows a case where one melting torch 30 is used and the melting arc 31 is applied to the position of the rotation center C of the metal rod 2. FIG. In this case, only the vicinity of the central portion of the metal rod 2 is melted, and the concave shape 91 becomes a shape in which the central portion is deeply melted. Since the centrifugal force weakens as it approaches the outer peripheral surface of the surface 2a, it accumulates in the outer peripheral portion 2c of the tip surface of the metal rod 2. This molten metal 90a scatters from the outer peripheral portion 2c of the tip end surface of the metal rod 2 as the released powder 93 after reaching a certain size. For this reason, it tends to be a powder with large and irregular grain sizes.

In FIG. 8(b), there is one melting torch 30 as in the case of FIG. It is a figure at the time of hitting the arc 31. FIG. In this case, the arc 31 for melting is irradiated to the intermediate position between the center of the metal rod 2 and the outer peripheral portion 2c of the tip surface of the metal rod 2, and the recessed shape 91 of the tip surface 2a becomes a relatively shallow recessed shape, and the molten metal 90a is melted. Sufficient centrifugal force also acts on the end face, and the metal rod 2 is smoothly detached from the outer peripheral portion 2c of the tip end face, and the released powder 93 having a small particle diameter is obtained. As the rotation progresses, the area of the melted surface 90 gradually decreases and the melted surface 90 disappears. Melting and solidification are continuously repeated by this rotation. Conventionally, if the metal rod 2 has a diameter of φ50 or less, the positional relationship between the metal rod 2 and the melting torch 30 as shown in FIG. If it is too small, the radius portion of the tip surface 2a cannot be uniformly melted as shown in FIG. 8(c), and the center portion remains convex. In this case, as the dissolving process of the metal rod 2 progresses, the convex portion at the center becomes higher and higher, and as a result, the shape of the outer peripheral portion 2c of the tip surface of the metal rod 2 collapses, and the released powder 93 scatters unevenly. . Also, if the irradiation position of the melting arc 31 is brought closer to the center of the tip surface 2a, the shape of the depression 91 becomes as shown in FIG. 8(a).

FIG. 8(d) shows a case where two melting torches 30 are used and the center of the metal rod 2 is between two melting arcs 31. FIG. In this case, the melted surface 90 becomes as shown in FIG. 8(d), and the temperature of the central portion of the metal rod 2 rises due to the increase in the amount of heat. It becomes a typical mortar-shaped dent shape. Therefore, the released powder 93 having a uniform and fine particle size can be obtained. Furthermore, by using a plurality of melting torches 30, the area of the solidification surface 92 is reduced, resulting in an increase in productivity. In this manner, by irradiating the tip surface 2a of the metal rod 2 with the melting arc 31 from the plurality of melting torches 30, uniform melting is possible even if the metal rod 2 has a large diameter, and the melting efficiency is improved. Up. The positions of the two melting torches 30 do not have to be rotationally symmetrical with respect to the center of rotation C of the metal rod 2 . Furthermore, when a plurality of torches are used, a combination of a melting torch 30 and a power feeding torch 40 as in the power feeding structure examples shown in FIGS. The effect of making a uniform melting surface is obtained. This is because the power supply torch 40 is also an arc heat source, and its heat quantity is somewhat inferior to that of the melting torch 30, and the metal rod 2 can be melted although the efficiency is slightly reduced.

(Power supply structure example 3)
In the power feeding structure shown in FIG. 9, the power feeding torch 40 is arranged around the melting torch 30. As shown in FIG. The melting torch 30 of this power supply structure is a cathode plasma torch, and the power supply torch 40 is an anode torch. The power supply torch 40 is fixed in a state in which the tip thereof faces the tip surface 2a of the metal rod 2, that is, the end surface 20a of the rotating body 20 on the metal rod mounting side. Further, the power feeding torch 40 is arranged at an angle with respect to the melting torch 30 . Also in this power supply structure, the powder can be manufactured in a state in which the power supply torch 40 is not in contact with the metal rod 2 .

In this power supply structure, one melting torch 30 is sandwiched between two power supply torches 40 . The power supply torch 40 is arranged line-symmetrically with respect to the rotation center C of the rotating body 20 . According to such an arrangement, the magnetic flux generated from each arc becomes as shown in FIG. Since the symmetrical force F acts and the force is balanced, the magnetic blow of the melting arc 31 can be suppressed. In addition, the power feeding arc 41 of each power feeding torch 40 is directed away from the center of the metal rod tip surface 2a by the arc current of the melting arc 31 (current value twice the current of the power feeding arc 41). of Lorentz force F _D is generated. On the other hand, the power feeding torch 40 of this power feeding structure is disposed so that the tip portion 40a faces the central portion of the tip surface 2a of the metal rod 2 at an angle. As a result, in the vicinity of the tip 40a of the feeding torch 40, the feeding arc 41 is formed so as to go toward the center of the metal rod tip face 2a. It bends in the direction away from the melting arc 31 under the influence of the force F _D , and as a result is formed in a direction parallel to the axial direction A of the rotating body 20 . As a result, the entire tip surface 2a of the metal rod 2 is uniformly irradiated with the plasma arc. That is, by arranging the power supply torch 40 so as to be inclined with respect to the melting torch 30, the magnetic blow can be suppressed to some extent, and the arc can be applied to the target position. The angle of inclination of the power supply torch 40 with respect to the melting torch 30 is appropriately changed according to the magnitude of the supplied current and the like.

In the example of FIG. 9, the number of power feeding torches 40 is two, but three or more may be arranged. In addition, from the viewpoint of suppressing the magnetic blow of the melting torch 30, a plurality of power supply torches 40 are provided, and the rotation center of the rotating body 20 when the melting torch 30 is viewed from the axial direction A of the rotating body 20 It is preferable that the feeding torches 40 are arranged symmetrically with C as the symmetrical point. If the power supply torch 40 is arranged in such a manner, the effect of suppressing the magnetic blow of the melting torch 30 is enhanced.

(Power supply structure example 4)
As the current supplied to the melting torch 30 and the power supply torch 40 increases, the strength of the magnetic field increases, making magnetic blow more likely to occur. The power supply structure shown in FIG. 10 is a power supply structure suitable for such a high current flow. In this power supply structure, the melting torch 30 is a plasma cathode torch, and the power supply torch 40 is a plasma anode torch. In this power supply structure, the power supply torch 40 is arranged so that the tip of the power supply torch 40 faces the tip surface 2a of the metal rod 2 on the melting side, and the melting torch 30 is positioned relative to the power supply torch 40. It is arranged around the feeding torch 40 so as to be inclined. That is, in this power supply structure, one power supply torch 40 is sandwiched between two melting torches 30. arranged symmetrically. Therefore, since the Lorentz force F caused by the arc current of one melting torch 30 and the Lorentz force F caused by the arc current of the other melting torch 30 are offset, the power supply torch 40 emits light. The plasma arc is oriented parallel to the axial direction A of the rotor 20 .

The plasma arc between the melting torch 30 and the metal rod 2 is separated from the center of the metal rod tip surface 2a due to the arc current of the power supply torch 40 (current value twice the current of the melting arc 31). A directional Lorentz force F _D acts. When the supply current is high, it is not possible to cope with this by simply tilting the melting torch 30 with respect to the power supply torch 40, so it is preferable to provide the magnetic force generator 85 as in this power supply structure.

The magnetic force generator 85 in this power supply structure is provided outside the melting torch 30 . In other words, the melting torch 30 is arranged between the power feeding torch 40 and the magnetic force generator 85 . The magnetic force generator 85 has an L-shaped conductor 86 made of a metal material (for example, copper). and an inclined portion 88 extending outward from the melting torch 30 from 87a. Since the conductor 86 has such an L-shaped structure, it does not intersect with the scattering direction of the released powder 93 emitted from the tip surface 2a of the metal rod 2. As shown in FIG. An end portion 87a of the parallel portion 87 on the rotor side is located closer to the rotor 20 than the tip portion 30a of the melting torch 30 is. A slanted portion 88 of the conductor 86 is connected to the cathode side of the plasma power source 16 and a parallel portion 87 of the conductor 86 is electrically connected to the melting torch 30 . In the case of such a power supply structure, in the vicinity of the tip 30a of the melting torch 30, the current flowing between the melting torch 30 and the metal rod 2 and the current flowing through the parallel portion 87 of the conductor 86 are in opposite directions. . For this reason, the melting arc 31 between the melting torch 30 and the metal rod 2 is acted upon by the Lorentz force _FJ directed toward the central portion of the tip surface 2a of the metal rod. The Lorentz force F _D from the power feeding torch 40 and the Lorentz force F _J from the conductor 86 are canceled, but since the current of the power feeding arc 41 is twice the current of the melting arc 31, F _D >F _J , and in the vicinity of the tip end face 2a of the metal rod 2, the melting arc 31 is swung away from the center of the tip end face 2a of the metal rod 2. FIG. That is, the melting arc 31 emitted from the inclined melting torch 30 is oriented parallel to the axial direction A of the rotating body 20 in the vicinity of the tip surface 2a of the metal rod 2 . As a result, the entire tip surface 2a of the metal rod 2 can be uniformly irradiated with the plasma arc.

In the case of this power supply structure, the inclination angle θ of the melting torch 30 with respect to the power supply torch 40 is preferably 45° or less. Moreover, although the number of melting torches 30 is two in the example of FIG. 10, three or more may be arranged. Further, from the viewpoint of suppressing the magnetic blow of the power supply torch 40, a plurality of melting torches 30 are provided, and when the power supply torch 40 is viewed from the axial direction A of the rotor 20, the rotation center of the rotor 20 It is preferable that the melting torches 30 are arranged point-symmetrically with C as the point of symmetry. Such arrangement of the melting torch 30 enhances the effect of suppressing the magnetic blow of the power supply torch 40 . The number and arrangement of the magnetic force generators 85 are appropriately changed according to the number and arrangement of the melting torches 30 and the like. Moreover, although the conductor 86 of the magnetic force generator 85 in this power supply structure is L-shaped, the shape of the conductor 86 is not particularly limited as long as it has a parallel portion 87 with respect to the melting arc 31 . Also, the structure of the magnetic force generator 85 is not limited to the structure described in the example of FIG.

(Power supply structure example 5)
The power supply structure shown in FIG. 11 is a structure in which a power supply torch 40 and a plurality of melting torches 30 are integrated. The power supply torch 40 in this power supply structure is a plasma anode torch, and the melting torch 30 is a plasma cathode torch. As shown in FIGS. 11 and 12, in this power supply structure, the power supply torch 40 is disposed so that the tip end of the power supply torch 40 faces the tip surface 2a of the metal rod 2 on the melting side. , are arranged so as to be parallel to the power feeding torch 40 and surround the power feeding torch 40 . When the power supply torch 40 and the melting torch 30 are arranged in this manner, the melting arc 31 between the melting torch 30 and the metal rod 2 is separated from the center of the metal rod tip surface 2a as described above. A directional Lorentz force F acts.

Since the melting torch 30 in the present power supply structure is a plasma torch, the tip 30a of the melting torch 30 is provided with an outlet 32 for blowing out the plasma gas, as shown in FIG. The hole center C _h of the blow-out port 32 is inclined with respect to the axial direction A of the rotating body 20, and the blow-out port 32 faces toward the central portion of the metal bar tip surface 2a. According to the melting torch 30 having such an inclined outlet 32, while the melting arc 31 is formed from the melting torch 30 toward the central portion of the tip surface 2a of the metal rod 2, In the vicinity of the tip surface 2 a of 2 , the melting arc 31 is irradiated in a direction parallel to the rotation direction R of the rotating body 20 under the influence of the Lorentz force F caused by the arc current of the power supply torch 40 . As a result, the tip surface 2a of the metal rod 2 is irradiated with a plasma arc from the feeding torch 40 and the melting torch 30 parallel to the rotation direction R of the rotating body 20, and the tip surface 2a of the metal rod 2 is irradiated over a wide range. is dissolved. As described above, by inclining the outlet 32 of the melting torch 30, the magnetic blow of the melting torch 30 can be suppressed.

From the viewpoint of suppressing the magnetic blow of the power feeding torch 40, a plurality of the melting torches 30 are provided, and the rotation center of the rotating body 20 when the melting torch 30 is viewed from the axial direction A of the rotating body 20 It is preferable that the melting torches 30 are arranged point-symmetrically with C as the point of symmetry. Moreover, the power supply torch 40 and the melting torch 30 may not be integrated. For example, even if the melting torch 30 is arranged parallel to the power feeding torch 40 at a position slightly separated from the power feeding torch 40, the effect of suppressing the magnetic blow described above can be obtained if the outlet 32 is inclined. . The inclination angle of the blowout port 32 is appropriately changed according to the positional relationship between the power supply torch 40 and the melting torch 30, the magnitude of the supplied current, and the like.

(Power supply structure example 6)
The power supply structure shown in FIGS. 14 and 15 is an example in which the melting torch 30 and the power supply torch 40 are arranged in parallel. The melting torch 30 in this power supply structure is a plasma cathode torch, and the power supply torch 40 is a plasma anode torch. As shown in FIG. 15, in this power supply structure, the power supply torch 40 is disposed so that the tip end of the power supply torch 40 faces the tip surface 2a of the metal rod 2 on the melting side. A plurality of 40 are provided. The melting torches 30 and the power supply torches 40 are alternately arranged along the rotation direction R of the rotating body 20, and are arranged point-symmetrically with the rotation center C of the rotating body 20 as a point of symmetry. In the example of FIG. 15, two melting torches 30 and two power feeding torches 40 are provided, the intervals between adjacent melting torches 30 and power feeding torches 40 are equal to each other, and the melting torches 30 located on the diagonal line are equal to each other. , and the interval between the feeding torches 40 positioned on the diagonal line are equal to each other.

According to this power supply structure, a mutually attracting Lorentz force is generated between the torches of the same polarity, and a mutually repelling Lorentz force is generated between the torches of different polarities. As a result, the respective Lorentz forces cancel each other, so that the plasma emitted from the melting torch 30 and the power feeding torch 40 is directed parallel to the axial direction A of the rotating body 20, and the tip surface 2a of the metal rod 2 to reach As a result, the plasma arc can be irradiated in parallel with the tip surface 2a of the metal rod 2, so that a wide range of the tip surface 2a of the metal rod 2 can be melted. In this manner, the melting torches 30 and the power supply torches 40 are alternately arranged along the rotation direction R of the rotating body 20, and are arranged point-symmetrically with the rotation center C of the rotating body 20 as a point of symmetry. You can suppress blowing.

Although one example of the embodiment of the present invention has been described above, the present invention is not limited to this example. It is obvious that a person skilled in the art can conceive various modifications or modifications within the scope of the technical idea described in the claims, and these are also within the technical scope of the present invention. be understood to belong to

For example, although various power supply structures have been described in the above embodiments, the power supply structure is not limited to these structural examples. For example, the various power supply structures described in the above embodiments may be combined with each other within a range that does not hinder the execution of powder production. Also, the pole (anode or cathode) of each torch may be opposite to that described in the above embodiments, as long as it does not interfere with the powder production.

INDUSTRIAL APPLICABILITY The present invention can be used for a powder manufacturing apparatus using a plasma rotating electrode method.

1 powder manufacturing apparatus 2 metal rod 2a metal rod tip surface 2b metal rod outer peripheral surface 2c metal rod tip surface outer peripheral portion 10 chamber 11 gas supply pipe 12 gas exhaust pipe 13 vacuum pump 14 drive source 15 drive shaft 16 plasma power supply 20 Rotating body 20a End face 21 on metal rod mounting side Spindle 22 Metal rod holder 30 Melting torch 30a Melting torch tip 31 Melting arc 32 Blowout port 40 Power supply torch 40a Power supply torch tip 41 Power supply arc 50 rotator housing chamber 51 wall 60 magnet coupling 61 spindle side part 62 drive shaft side part 70 static pressure gas bearing 80 magnetic force generator 81 conductor 82 parallel part 82a rotor side end 83 of parallel part inclined part 85 magnetic force generation Machine 86 Conductor 87 Parallel part 87a End part 88 of the parallel part on the rotating body side Inclined part 90 Molten surface 90a Molten metal 91 Recessed shape 92 Solidified surface 93 Discharged powder A Axial direction C of the rotating body Rotational center _C of the rotating body Hole center F Lorentz force due to the effect of the magnetic field of the arc current F _D Lorentz force due to the effect of the magnetic field of the arc current F _J Lorentz force due to the effect of the magnetic field of the magnetic force generator R angle

Claims (13)

a chamber in which the metal rod is melted;
a rotating body to which the metal rod is attached at an end in the axial direction;
a melting torch that irradiates an arc on the tip surface of the metal rod;
a power feeding electrode having a polarity different from that of the melting torch when energized,
The power supply electrode is arranged in the vicinity of the metal rod at a position that does not come into contact with the metal rod and allows current to flow through the metal rod and the arc. The rotating body comprises a spindle,
2. The powder manufacturing apparatus according to claim 1, comprising a static pressure gas bearing that supports said spindle. The rotating body includes a spindle to which the metal rod is attached and a magnetic coupling,
3. The powder manufacturing apparatus according to claim 1, wherein a driving shaft for rotating said spindle and said spindle are connected by said magnetic coupling. The powder production apparatus according to any one of claims 1 to 3, wherein the power supply electrode is arranged at a position facing the outer peripheral surface of the metal rod attached to the rotating body. a plurality of said melting torches;
a magnetic force generator;
The melting torches are arranged side by side along the rotation direction of the rotating body,
5. The powder manufacturing apparatus according to claim 4, wherein said magnetic force generator is configured to generate magnetic force for canceling Lorentz force generated by arc current of said melting torch. The magnetic force generator comprises a conductor,
The melting torch is arranged between the rotation center of the rotating body and the conductor,
6. The powder manufacturing apparatus according to claim 5, wherein said conductor has a parallel portion extending parallel to said melting torch. The power supply electrode is arranged around the melting torch,
The powder manufacturing apparatus according to any one of claims 1 to 3, wherein the tip portion of the power supply electrode faces the tip surface of the metal rod on the dissolving side. 8. The powder manufacturing apparatus according to claim 7, wherein said power feeding electrode is arranged to be inclined with respect to said melting torch. The power supply electrode is arranged such that the tip of the power supply electrode faces the tip surface of the metal rod on the melting side,
The powder manufacturing apparatus according to any one of claims 1 to 3, wherein the melting torch is arranged around the power supply electrode so as to be inclined with respect to the power supply electrode. Equipped with a magnetic force generator,
10. The powder manufacturing apparatus according to claim 9, wherein said magnetic force generator is configured to generate a magnetic force for canceling Lorentz force generated by arc currents of said feeding electrode and said melting torch. . The magnetic force generator comprises a conductor,
The melting torch is arranged between the power supply electrode and the conductor,
11. The powder manufacturing apparatus according to claim 10, wherein said conductor has a parallel portion extending parallel to said melting torch. The power supply electrode is arranged such that the tip of the power supply electrode faces the tip surface of the metal rod on the melting side,
The melting torch is arranged parallel to the power supply electrode around the power supply electrode,
The melting torch has a plasma gas outlet,
The powder manufacturing apparatus according to any one of claims 1 to 3, wherein the hole center of the blowout port is inclined with respect to the axial direction of the rotating body. a plurality of said melting torches;
and the same number of power supply electrodes as the melting torch,
The power supply electrode is arranged such that the tip of the power supply electrode faces the tip surface of the metal rod on the melting side,
The melting torches and the power supply electrodes are alternately arranged along the rotation direction of the rotating body, and when the melting torches and the power supply electrodes are viewed from the axial direction of the rotating body, The powder manufacturing apparatus according to any one of claims 1 to 3, arranged point-symmetrically about the center of rotation of the body.

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