Spindle for plasma rotating electrode method

Abstract

To provide a spindle for plasma rotating electrode process which enables reduction of repair costs needed when a bearing is broken and can prevent occurrence of looseness of a joint part and inhibit axial run-out during rotation.SOLUTION: A spindle body 11 has: a bush part 21 which is provided in a manner that one end part of an electrode member may be attached to the tip side; an attachment part 22 which is provided at the rear end side so as to be attachable to rotation driving means; and an intermediate part 23 provided between the bush part 21 and the attachment part 22. The spindle body 11 is formed by a member in which an outer shape of a cross section perpendicular to a length direction forms a generally circular shape and at least the bush part 21 and the intermediate part 23 are integrally molded.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spindle for a plasma rotating electrode process. [Background technology]

[0002] A conventional powder manufacturing apparatus using the plasma rotating electrode method has a chamber, a long, thin, cylindrical electrode member made of a metal or alloy, with its tip located inside the chamber and rotatable around a central axis along the length direction, and a plasma irradiation means capable of irradiating plasma toward the tip of the electrode member.The electrode member is rotated inside the sealed chamber filled with an atmospheric gas such as Ar or He, and plasma is irradiated by the plasma irradiation means to melt the tip of the electrode member, and the molten liquid is blown away and solidified inside the chamber by the centrifugal force of the rotation of the electrode member, thereby producing spherical metal or alloy powder (see, for example, Non-Patent Documents 1 to 3).

[0003] In such a conventional powder manufacturing apparatus, as shown in Fig. 5, a spindle 50 for rotating an electrode member is formed by attaching bearings 52 to both ends of an intermediate section 51, pressing a bush 54 into the front end of the intermediate section 51 via a nut 53, and pressing a mounting member 56 into the rear end of the intermediate section 51 via a nut 55. When manufacturing powder, an electrode member is attached to a mounting hole 54a of the bush 54, a rotation drive means such as a motor is attached to the mounting member 56 via a coupling, and with the spindle 50 supported at the position of the two bearings 52, the spindle 50 is rotated by the rotation drive means to rotate the electrode member. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Koji Kakei, Rei Yokomori, Tomohiro Nishimaki, "Microstructure and strength of powder sintered nickel superalloys produced by plasma rotating electrode method", Journal of the Japan Institute of Metals, Vol. 80, No. 8, 2016, pp. 508-514 [Non-Patent Document 2] Masaharu Tokizane, Kazuo Isonishi, "Production of Ti Alloy Powder by Plasma Rotating Electrode Method", Resource Processing Technology, 1990, Vol.37, No.4, pp.215-221 [Non-Patent Document 3] Ryohei Kumagai, "Preparation of Metallic Spherical Powders by Plasma Rotating Electrode Method", Materia, 1998, Vol. 37, No. 6, pp. 488-494 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional spindle 50 as shown in Fig. 5, the bearing 52 cannot be removed, and therefore when the bearing 52 is damaged, it is not possible to replace only the bearing 52. This necessitates the replacement of the entire spindle 50, which increases the repair costs. In addition, because the bushing 54 is pressed in and joined, there are problems such as loosening of the joint due to poor contact, loosening of the joint due to thermal expansion during use, and shaft wobble during rotation due to a small gap in the joint.

[0006] The present invention has been made with attention to these problems, and aims to provide a spindle for plasma rotating electrode processing that can reduce repair costs when bearings are damaged, does not cause loosening of joints, and suppresses axial wobble during rotation. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the spindle for a plasma rotating electrode method according to the present invention is a spindle for use in a plasma rotating electrode method in which a long, cylindrical electrode member made of a metal or alloy is rotated around a central axis along the longitudinal direction by a rotary drive means, and a plasma is irradiated to the tip of the rotating electrode member to produce a powder made of a metal or alloy, the spindle having a bush portion at the tip end so that one end of the electrode member can be attached, an attachment portion at the rear end so that it can be attached to the rotary drive means, and an intermediate portion provided between the bush portion and the attachment portion, the spindle body having an outer shape of a cross section perpendicular to the longitudinal direction that is approximately circular, and consisting of a member in which at least the bush portion and the intermediate portion are integrally molded.

[0008] The spindle for the plasma rotating electrode method according to the present invention is made of a member in which at least the bushing portion and the intermediate portion are integrally molded, and therefore does not loosen the joint, which occurs when multiple members are joined by press fitting or the like. In addition, since no shaft wobble occurs during rotation due to a gap at the joint, shaft wobble during rotation can be suppressed. This improves the rotation accuracy of the electrode member.

[0009] The spindle for plasma rotating electrode processing according to the present invention is configured so that the bearings can be attached later at predetermined positions in the integrally molded bushing and intermediate portion, which makes it relatively easy to attach and remove the bearings. Therefore, when the bearings are damaged, only the damaged bearing can be replaced, which reduces repair costs compared to replacing the entire spindle.

[0010] The spindle for the plasma rotating electrode method according to the present invention has a tip side bearing, and the intermediate portion has a bearing insert portion at an end portion on the bush portion side, and the outer diameter of the bearing insert portion is smaller than the outer diameter of the bush portion and is equal to or larger than the outer diameter of the portion other than the bearing insert portion and the mounting portion, and the tip side bearing is preferably annular, has an inner diameter the same as the outer diameter of the bearing insert portion, and is mounted by inserting the bearing insert portion inside. In this case, the tip side bearing can be mounted at the position of the bearing insert portion by inserting the spindle body from the mounting portion side into the inside of the tip side bearing. Also, the tip side bearing mounted at the position of the bearing insert portion can be removed from the spindle body by moving the tip side bearing mounted at the position of the bearing insert portion to the mounting portion side. This makes it possible to easily replace only the damaged tip side bearing when the tip side bearing is damaged.

[0011] In this case, it is preferable that the intermediate portion has a spacer attached to the outer surface of the portion other than the bearing insert portion so that the tip side bearing is held in the bearing insert portion. In this case, the spacer can prevent the tip side bearing from coming off the bearing insert portion. Furthermore, when replacing the tip side bearing, the spacer can be removed to easily replace the tip side bearing.

[0012] The spacer may be, for example, tubular with a cylindrical inner hollow portion, and may be attached by inserting the portion of the intermediate portion other than the bearing insertion portion into the hollow portion. The spacer may be provided to cover the outer surface of the portion of the intermediate portion other than the bearing insertion portion, and may be made of one or more members. The spacer may be made of two members split along the central axis of the cylindrical hollow portion, and each member may be provided so as to be fixed to each other, sandwiching the portion of the intermediate portion other than the bearing insertion portion from the side. In this case, the spacer can be easily attached by the two split members. The members can be fixed to each other, for example, by screws or the like. Effect of the Invention

[0013] According to the present invention, it is possible to provide a spindle for a plasma rotating electrode process which can reduce repair costs when a bearing is damaged, does not cause loosening of joints, and suppresses axial wobble during rotation. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of a spindle for a plasma rotating electrode process according to an embodiment of the present invention, with a part of a spacer cut away. FIG. [Diagram 2] FIG. 2 is a perspective view showing a first modified example of a spindle for a plasma rotating electrode process according to an embodiment of the present invention, with a part of a spacer cut away. [Diagram 3] 1A and 1B are perspective views showing a second modified example of a spindle for a plasma rotating electrode process according to an embodiment of the present invention, in which FIG. [Figure 4] 13A and 13B are a perspective view and a sectional view of a spacer, showing a third modified example of a spindle for a plasma rotating electrode process according to an embodiment of the present invention. [Diagram 5] FIG. 1 is a perspective view showing a spindle for a conventional plasma rotating electrode method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 4 show a spindle for a plasma rotating electrode method according to an embodiment of the present invention. As shown in FIG. 1, a spindle 10 for a plasma rotating electrode process has a spindle body 11, a fixing nut 12, a front end bearing 13, a rear end bearing 14, and a spacer 15.

[0016] The plasma rotating electrode method is a method for producing metal or alloy powder by rotating a long, cylindrical electrode member made of a metal or alloy around a central axis along its length using a rotary drive means and irradiating plasma onto the tip of the rotating electrode member.

[0017] The spindle body 11 is elongated, and the outer shape of a cross section perpendicular to the longitudinal direction is approximately circular. The spindle body 11 has a bushing portion 21 at the front end, an attachment portion 22 at the rear end, and an intermediate portion 23 provided between the bushing portion 21 and the attachment portion 22. The spindle body 11 is made of a member in which the bushing portion 21 and the intermediate portion 23 are integrally molded.

[0018] The bushing 21 has an electrode mounting hole 21a at the tip end surface for inserting and mounting one end of an electrode member. The intermediate portion 23 is cylindrical, has a tip bearing insert 23a at the end on the bushing 21 side, and has a rear end bearing insert 23b at the end on the mounting portion 22 side. The outer diameter of the tip bearing insert 23a of the intermediate portion 23 is smaller than the outer diameter of the bushing 21 on the intermediate portion 23 side, and has the same size as the outer diameter of the central body portion 23c between the tip bearing insert 23a and the rear end bearing insert 23b. The outer diameter of the tip bearing insert 23a may be smaller than the outer diameter of the central body portion 23c. In addition, the outer diameter of the rear end bearing insert 23b is smaller than the outer diameters of the tip bearing insert 23a and the central body portion 23c. The mounting portion 22 is provided so as to be mountable to the rotation drive means via a coupling. The mounting portion 22 has an overall outer diameter smaller than the outer diameter of the rear end bearing insert 23b. The attachment portion 22 is joined to the rear end side of the intermediate portion 23 by press-fitting via a fixing nut 12. The fixing nut 12 has an outer diameter equal to or smaller than the outer diameter of the central body portion 23c.

[0019] The front end bearing 13 is made of an annular bearing. The inner diameter of the front end bearing 13 is the same as the outer diameter of the front end bearing insert portion 23a, and the front end bearing insert portion 23a is inserted inside the position of the front end bearing insert portion 23a and attached. The rear end bearing 14 is made of an annular bearing. The inner diameter of the rear end bearing 14 is smaller than the outer diameter of the fixing nut 12 and is the same as the outer diameter of the rear end bearing insert portion 23b. The rear end bearing 14 is installed at the position of the rear end bearing insert portion 23b by inserting the rear end bearing insert portion 23b inside. The rear end bearing 14 has an outer diameter equal to or smaller than the outer diameter of the central body portion 23c.

[0020] Spacer 15 is cylindrical and has an inner diameter equal to the outer diameter of central body 23c. Spacer 15 is attached to the outer surface of central body 23c by inserting central body 23c into cylindrical hollow portion 15a. Spacer 15 is attached with its tip end face in contact with tip bearing 13 so that tip bearing 13 is held in tip bearing inserting portion 23a.

[0021] The spindle 10 for the plasma rotating electrode method is assembled as follows. That is, after the rear end bearing 14 is attached to the rear end bearing inserting portion 23b, the mounting portion 22 is joined to the rear end side of the intermediate portion 23 via the fixing nut 12. This makes it possible to prevent the rear end bearing 14 from coming off the rear end bearing inserting portion 23b. Also, after joining the mounting portion 22 or before attaching the rear end bearing 14, the spindle body 11 is inserted from the rear end side of the spindle body 11 into the inside of the tip end bearing 13, and the tip end bearing 13 is attached to the position of the tip end bearing inserting portion 23a. After attaching the tip end bearing 13, the spacer 15 is attached by inserting the spindle body 11 into the hollow portion 15a of the spacer 15 from the rear end side of the spindle body 11. This makes it possible to prevent the tip end bearing 13 from coming off the tip end bearing inserting portion 23a. In this manner, the spindle 10 for the plasma rotating electrode method can be assembled.

[0022] Furthermore, when removing the tip side bearing 13, first the spacer 15 is moved toward the rear end of the spindle body 11 and removed, and then the tip side bearing 13 is moved toward the rear end of the spindle body 11. This allows the tip side bearing 13 to be removed from the spindle body 11. In this way, the tip side bearing 13 can be attached later to the spindle 10 for the plasma rotating electrode method, and the tip side bearing 13 can be attached and removed relatively easily. Therefore, when the tip side bearing 13 is damaged, only the damaged tip side bearing 13 can be replaced, which reduces repair costs compared to replacing the entire spindle.

[0023] When producing powder by the plasma rotating electrode method, the spindle 10 for the plasma rotating electrode method can be used to rotate the electrode member as follows. That is, first, the electrode member is attached to the electrode attachment hole 21a of the bush portion 21, and a rotation drive means such as a motor is attached to the attachment portion 22 via a coupling. With the spindle 10 for the plasma rotating electrode method supported at the positions of the front end bearing 13 and the rear end bearing 14, the spindle body 11 is rotated by the rotation drive means. This allows the electrode member to rotate together with the spindle body 11.

[0024] The spindle 10 for the plasma rotating electrode method is made of a member in which the bushing portion 21 and the intermediate portion 23 are integrally molded, so there is no loosening of the joints that occurs when multiple members are joined by press fitting, etc. Also, since there is no axial wobble during rotation due to gaps in the joints, it is possible to suppress axial wobble during rotation and improve the rotational accuracy of the electrode member.

[0025] When the plasma rotating electrode method spindle 10 shown in FIG. 1 was used to produce powder by the plasma rotating electrode method, the number of times the entire spindle had to be replaced was reduced to about one-third compared to the conventional one shown in FIG. 5. This also improved the powder production rate, which was about four times higher than that of the conventional one shown in FIG. 5. Furthermore, with the plasma rotating electrode method spindle 10 shown in FIG. 1, axial wobble during rotation is suppressed, making it possible to use electrode members with a higher specific gravity (heavier) than the electrode members used in the conventional one shown in FIG. 5.

[0026] As shown in Fig. 2, in the spindle 10 for the plasma rotating electrode process, the spacer 15 may be cut along a plane perpendicular to the central axis of the hollow portion 15a and divided into a plurality of cylindrical members 31. In a specific example shown in Fig. 2, the spacer 15 is made up of four members 31. In this case, it is possible to easily attach the spacer 15 to the spindle body 11 and remove it from the spindle body 11, compared to the single long cylindrical spacer 15 shown in Fig. 1.

[0027] As shown in FIG. 3, the spindle 10 for the plasma rotating electrode method may have a spacer 15 that is made up of an inner spacer 32a and an outer spacer 32b that covers the inner spacer 32a, and the inner spacer 32a may be made up of two members that are divided along the central axis of the hollow portion 15a. In this case, the inner spacer 32a can be easily attached by sandwiching the central body portion 23c of the spindle body 11 from the sides with the two divided members. The inner spacer 32a can be fixed by the outer spacer 32b. In this case, the overall thickness of the spacer 15 can be increased, so that the outer diameter of the central body portion 23c of the spindle body 11 can be made smaller than the outer diameter of the tip bearing insert portion 23a. This makes it easier to attach the tip bearing 13 to the tip bearing insert portion 23a, and by increasing the overall thickness of the spacer 15, the tip bearing 13 can be prevented from coming off the tip bearing insert portion 23a.

[0028] Also, as shown in Fig. 4, the spindle 10 for the plasma rotating electrode method may have a spacer 15 formed of two short cylindrical members 33 split along the central axis of the hollow portion 15a, and the members 33 may be arranged so as to be fixed to each other while sandwiching the central trunk portion 23c of the spindle body 11 from the sides. In a specific example shown in Fig. 4, the members 33 can be fixed to each other by screws 34. In this case, the spacer 15 can be easily attached to the two split members 33.

[0029] 4, the outer diameter of the spindle body 11 may gradually increase from the attachment portion 22 toward the tip bearing insertion portion 23a of the intermediate portion 23. In this case, it is possible to easily attach the tip bearing 13 and the rear end bearing 14. Also, as shown in FIG. 4, the end portion of the bush portion 21 on the intermediate portion 23 side may have a flange 35 having an outer diameter larger than the outer diameter of the tip bearing 13. [Explanation of symbols]

[0030] 10. Spindle for plasma rotating electrode method 11 Spindle body 21 Bush section 21a Electrode mounting hole 22 Mounting part 23 Middle Section 23a End bearing insert 23b Rear end bearing insert 23c Central torso 12 Fixing nut 13 Tip bearing 14 Rear end bearing 15 Maza 15a Hollow part 31 Materials 32a Inner spacer 32b Outer spacer 33 Materials 34 Screws 35 Flange 50 Spindle 51 Middle section 52 Bearings 53 Nut 54 Bush 54a Mounting hole 55 Nut 56 Mounting material

Claims

[Claim 1] A spindle for a plasma rotating electrode process used in a plasma rotating electrode process in which a thin and long cylindrical electrode member made of a metal or alloy is rotated around a central axis along a length direction by a rotary drive means and a tip of the rotating electrode member is irradiated with plasma, thereby producing a powder made of a metal or alloy, a spindle body having a bush portion provided at a front end thereof so that one end of the electrode member can be attached thereto, an attachment portion provided at a rear end thereof so that the attachment can be attached to the rotation drive means, and an intermediate portion provided between the bush portion and the attachment portion; A tip side bearing, It has a spacer and the spindle body is made of a member in which a cross section perpendicular to a longitudinal direction thereof is substantially circular in shape, and at least the bush portion and the intermediate portion are integrally formed; the intermediate portion has a bearing insertion portion at an end portion on the bush portion side, the outer diameter of the bearing insertion portion being smaller than the outer diameter of the bush portion and equal to or larger than the outer diameter of the portion other than the bearing insertion portion and the mounting portion, the tip-side bearing is annular, has an inner diameter equal to the outer diameter of the bearing insert portion, and is attached by inserting the bearing insert portion into the tip-side bearing; the spacer is attached to an outer surface of a portion of the intermediate portion other than the bearing insertion portion in contact with the tip side bearing so that the tip side bearing is held in the bearing insertion portion, The spacer is tubular, has a cylindrical inner hollow portion, and is composed of two members divided along the central axis of the hollow portion, and the members are provided so as to be fixed to each other by sandwiching the portion of the intermediate portion other than the bearing insertion portion from the sides, and is attached by inserting the portion of the intermediate portion other than the bearing insertion portion into the hollow portion. A spindle for a plasma rotating electrode method.

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