Plasma processing apparatus

Abstract

The invention provides a plasma processing device which does not need an electric bearing (a collector ring) or an electric brush for rotating a charged housing, is simple in structure and low in cost, and can reduce the risk of contact with a rotating cylinder part. The plasma processing apparatus includes: an inner electrode; an electrode holder; an outer electrode formed in a cylindrical shape and surrounding the inner electrode and the electrode holder; an insulating tube disposed between the inner electrode and the electrode holder, and the outer electrode, the insulating tube surrounding the inner electrode and the electrode holder; a rotating cylinder part which is made of an insulating material, is formed in a cylinder shape surrounding the outer electrode, and can rotate relative to the outer electrode around the central axis of the inner electrode; and a drive mechanism that rotates the rotating cylinder part.

Description

Technical Field

[0001] The present disclosure relates to a plasma processing apparatus. Background Art

[0002] In the past, it is known that in a welding torch used for plasma treatment of the surface of a workpiece such as a synthetic resin, the nozzle of the welding torch that irradiates plasma is rotated for reasons such as corresponding to the shape of the workpiece. For example, Japanese Patent Publication No. 2001-68298 discloses a plasma nozzle having an electrode and a housing that can rotate relative to a support tube arranged around the electrode. The housing is made of metal, and when a voltage is applied to the electrode, an electrical discharge is generated between the electrode and the housing. The housing rotates with its axis as the center, so that the plasma jet beam draws the generatrix of a cone and irradiates the surface of the workpiece. Summary of the invention

[0003] In the plasma nozzle described in Japanese Patent Application Laid-Open No. 2001-68298, a housing that rotates relatively to the inner electrode is charged, and thus there is a risk of contact with the housing.

[0004] The present disclosure aims to provide a plasma processing device that does not require an electric bearing (collector ring) or an electric brush for rotating a charged housing, has a simple structure and is inexpensive, and can reduce the risk of contact with a rotating cylinder.

[0005] According to one aspect of the present disclosure, a plasma processing device comprises: an inner electrode to which a voltage is applied; an electrode holder which holds the inner electrode; an outer electrode which is formed in a cylindrical shape and surrounds the inner electrode and the electrode holder; an insulating tube which is arranged between the inner electrode and the electrode holder and the outer electrode and surrounds the inner electrode and the electrode holder; a rotating cylinder which is made of an insulating material and is formed in a cylindrical shape surrounding the outer electrode and is capable of rotating relative to the outer electrode around the center axis of the inner electrode; and a driving mechanism which rotates the rotating cylinder.

[0006] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a cross-sectional perspective view of a plasma processing apparatus according to one embodiment of the present disclosure.

[0008] Figure 2 is a cross-sectional view showing a front end portion of a plasma processing apparatus. DETAILED DESCRIPTION

[0009] The embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that in the drawings referred to below, the same or corresponding components are denoted by the same reference numerals.

[0010] Figure 1 1 is a cross-sectional perspective view of a plasma processing apparatus according to an embodiment of the present disclosure. The plasma processing apparatus 1 is suitable for surface modification of a workpiece and is also suitable for TIG welding.

[0011] like Figure 1 As shown, the plasma processing apparatus 1 includes an inner electrode 100 , an electrode holder 200 , a position adjustment member 250 , a support 300 , an outer electrode 400 , an insulating tube 500 , a rotating cylinder 600 , and a driving mechanism 700 .

[0012] The inner electrode 100 has a shape extending linearly. The inner electrode 100 is made of, for example, tungsten. A voltage is applied to the inner electrode 100 from a power source (not shown).

[0013] The electrode holder 200 holds the inner electrode 100 . The electrode holder 200 includes an inner holder 210 , an outer holder 220 , and a fin member 230 .

[0014] The inner holding body 210 holds the inner electrode 100 while being in contact with the outer peripheral surface of the inner electrode 100. The inner holding body 210 has a shape extending in a direction parallel to the central axis AX of the inner electrode 100. The inner holding body 210 is made of copper, for example. A slit extending in a direction parallel to the axial direction of the inner holding body 210 is formed at the front end portion of the inner holding body 210.

[0015] The outer holding body 220 surrounds the inner holding body 210. A reduced diameter portion that gradually reduces in diameter toward the front end is formed on the inner circumferential surface of the front end portion of the outer holding body 220. Therefore, by inserting the inner holding body 210 into the outer holding body 220, the front end portion of the inner holding body 210 is pressed into the reduced diameter portion of the outer holding body 220 and is pressed against the inner electrode 100. An internal thread portion is provided at the base end portion of the outer holding body 220.

[0016] The position adjusting member 250 can adjust the position of the inner electrode 100 relative to the electrode holding body 200. The position adjusting member 250 includes an adjusting portion 252 and a gripper 254.

[0017] The adjustment portion 252 is movable in the axial direction relative to the outer holding body 220. Specifically, the adjustment portion 252 is provided with an external thread portion that is threadedly engaged with an internal thread portion provided at the base end portion of the outer holding body 220. The adjustment portion 252 can adjust the relative position of the inner electrode 100 with respect to the electrode holding body 200 by adjusting the force (pressing force) that applies the inner holding body 210 in the axial direction relative to the outer holding body 220.

[0018] For example, by screwing the adjusting portion 252 relative to the outer holding body 220 in a state where the front end of the adjusting portion 252 is in contact with the base end of the inner holding body 210, the front end of the inner holding body 210 is urged toward the inner electrode 100 by the reduced diameter portion of the outer holding body 220. As a result, the front end of the inner holding body 210 is pressed against the inner electrode 100, and the relative position of the inner electrode 100 with respect to the electrode holding body 200 is determined.

[0019] On the contrary, by separating the adjustment portion 252 from the inner retaining body 210, the force applied to the inner retaining body 210 by the reduced diameter portion of the outer retaining body 220 is released, thereby enabling the inner electrode 100 to move relative to the electrode retaining body 200, even if the relative position of the inner electrode 100 relative to the electrode retaining body 200 changes.

[0020] The gripper 254 is connected to the base end of the adjustment part 252. The gripper 254 is connected to the base end of the adjustment part 252 so as not to rotate relative to the adjustment part 252. It should be noted that the adjustment part 252 and the gripper 254 may be integrally formed of the same material.

[0021] The support body 300 supports the electrode holding body 200. The support body 300 includes a support plate 310, an insulating plate 320, a block portion 330, and an intervening member 340.

[0022] The support plate 310 is formed in a disk shape. The support plate 310 is made of metal such as aluminum, for example. However, the support plate 310 may also be formed of an insulating material.

[0023] The insulating plate 320 is disposed in an opening provided in the support plate 310. The electrode holder 200 is disposed so as to penetrate the insulating plate 320. The insulating plate 320 has a gas introduction portion 322 (described later).

[0024] The block 330 is fixed to the insulating plate 320 by a fastening member such as a screw. The block 330 is fixed to the insulating plate 320 from one side in a direction parallel to the central axis AX of the inner electrode 100. The block 330 is made of a conductive material. The electrode holder 200 is arranged to penetrate the block 330. Specifically, the inner peripheral surface of the block 330 contacts the outer holder 220.

[0025] The interposing member 340 is made of an insulating material and is interposed between the outer retaining body 220 and the insulating plate 320. Figure 1 As shown, a recess 342 is formed on the outer peripheral surface of the intervening member 340. The recess 342 is continuous in a ring shape around the central axis AX. The recess 342 forms a space S between the insulating plate 320 and the intervening member 340.

[0026] The outer electrode 400 is formed in a tubular shape, more specifically, a cylindrical shape, and surrounds the inner electrode 100 and the electrode holder 200. The outer electrode 400 includes an outer electrode body 410 and a power supply tip 420.

[0027] The outer electrode body 410 is fixed to the support body 300 from the other side in a direction parallel to the central axis AX of the inner electrode 100. That is, the block 330 and the outer electrode body 410 are fixed to the insulating plate 320 so as to sandwich the insulating plate 320 from both sides in a direction parallel to the central axis AX.

[0028] The power supply tip 420 is connected to the front end of the outer electrode body 410. The power supply tip 420 includes a front end surface 420a located in the same plane as the front end 110 of the inner electrode 100 or located forward of the front end 110 (see Figure 2 ). The front end surface 420a is orthogonal to the central axis AX.

[0029] The insulating tube 500 is disposed between the inner electrode 100 and the electrode holder 200 and the outer electrode 400. The insulating tube 500 surrounds the inner electrode 100 and the electrode holder 200. The insulating tube 500 is formed in a cylindrical shape. The insulating tube 500 is made of ceramic or the like. The insulating tube 500 is sandwiched from both sides in a direction parallel to the central axis AX by the power supply tip 420 of the outer electrode 400 and the sandwiching member 340 of the support body 300.

[0030] A processing gas (argon, air, etc.) is supplied from a gas supply unit (not shown) into the insulating tube 500. The gas supply unit supplies the processing gas to the gas inlet unit 322 provided on the insulating plate 320. A gas flow path connected from the gas inlet unit 322 to the space S is formed in the insulating plate 320, and a through hole is formed in the interposing member 340. Therefore, the processing gas supplied from the gas supply unit flows into between the outer holding body 220 and the insulating tube 500 through the gas inlet unit 322, the gas flow path, and the through hole of the interposing member 340.

[0031] The fin member 230 is used to swirl the process gas supplied to the inner side of the insulating tube 500 to form a swirling flow FL around the inner electrode 100 (see Figure 2) component. The fin member 230 is connected to the front end portion 222 of the outer retaining body 220. In more detail, the fin member 230 is fitted relative to the front end portion 222 of the outer retaining body 220 from the outer peripheral side of the front end portion 222. A plurality of spiral grooves are formed on the outer peripheral surface of the fin member 230. The outer peripheral surface of the fin member 230 may be in contact with the inner peripheral surface of the insulating tube 500, or may be separated from the inner peripheral surface of the insulating tube 500. However, the outer peripheral surface of the fin member 230 is preferably in contact with the inner peripheral surface of the insulating tube 500. The fin member 230 is separated from the outer peripheral surface of the inner electrode 100.

[0032] The processing gas supplied to the inner side of the insulating tube 500 is converted into plasma near the front end portion 110 of the inner electrode 100. The insulating tube 500 defines the position where the plasma is generated between the inner electrode 100 and the outer electrode 400. Figure 2 As shown in the figure, the front end portion 110 of the inner electrode 100 can move between the retreat position P1 which is coplanar with the front end surface of the insulating tube 500 and the protruding position P2 which is coplanar with the front end surface 420a of the power supply tip 420. In other words, the electrode holder 200 holds the inner electrode 100 in such a manner that the front end portion 110 of the inner electrode 100 can move between the retreat position P1 and the protruding position P2.

[0033] like Figure 1 as well as Figure 2 As shown in FIG. 1 , the position of the front end portion 110 of the inner electrode 100 may be set to be exposed from the insulating tube 500. Figure 2 In the illustrated example, the position of the front end portion 110 is set between the retracted position P1 and the protruding position P2.

[0034] The rotating cylinder 600 is formed in a cylindrical shape surrounding the outer electrode 400. The rotating cylinder 600 is rotatable relative to the outer electrode 400 around the central axis AX. The rotating cylinder 600 is made of an insulating material. In this embodiment, the rotating cylinder 600 includes a rotating cylinder body 610 and a rotating nozzle 620.

[0035] The rotating cylinder body 610 is mounted around the outer electrode body 410. A bearing is disposed between the rotating cylinder body 610 and the outer electrode body 410. The rotating cylinder body 610 is made of, for example, polyetheretherketone (PEEK resin) or the like.

[0036] The rotating nozzle 620 is connected to the front end of the rotating cylinder body 610 in a manner that does not rotate relative to the rotating cylinder body 610. The rotating nozzle 620 is a part that blows out the plasma-generated rotating flow FL. Figure 2As shown in FIG. 1 , the opening (plasma blowing port) 620 b of the rotating nozzle 620 may be eccentric with respect to the central axis AX of the inner electrode 100 . The rotating nozzle 620 is made of, for example, polyetheretherketone (PEEK resin) or the like. Figure 2 As shown, the rotating nozzle 620 has an opposing surface 620 a that is opposed to the front end surface 420 a of the power supply tip 420 .

[0037] like Figure 2 As shown in the figure, a supply flow path 610a for supplying gas from the outside of the outer electrode 400 toward between the front end face 420a and the opposing face 620a may be formed in the rotating cylinder body 610. Alternatively, an annular groove may be formed in at least one of the front end face 420a and the opposing face 620a, and a sealing member such as an O-ring may be provided in the groove.

[0038] The driving mechanism 700 rotates the rotating cylinder 600. The driving mechanism 700 includes a motor M and a power transmission unit that transmits the output of the motor M to the rotating cylinder 600. In the present embodiment, the power transmission unit has a first gear 710 and a second gear 720. However, the power transmission unit may also be composed of, for example, a belt, a pulley, a roller chain, a sprocket, etc. In addition, instead of the motor M, a power source that generates a rotating force such as a gasoline engine, a diesel engine, a rotary cylinder, etc. may be used.

[0039] The motor M is fixed to the support plate 310 . The output shaft of the motor M passes through the support plate 310 .

[0040] The first gear 710 is connected to the output shaft of the motor M.

[0041] The second gear 720 is disposed so as to mesh with the first gear 710. The second gear 720 is disposed so as to surround the outer electrode 400. The rotation center of the second gear 720 is located on the central axis AX.

[0042] like Figure 1 As shown, the rotating cylinder body 610 in the rotating cylinder 600 has a receiving surface 612 that receives the second gear 720 in a direction parallel to the central axis AX. The second gear 720 is fixed to the rotating cylinder body 610 by a fastening member B that applies an axial force to press the second gear 720 against the receiving surface 612.

[0043] In the plasma processing apparatus 1 described above, when the processing gas is supplied from the gas supply unit (not shown) to the inside of the insulating tube 500, the processing gas passes through the grooves of the fin member 230 to form a swirling flow FL around the inner electrode 100, and is converted into plasma near the front end portion 110 of the inner electrode 100. On the other hand, when the motor M of the driving mechanism 700 is driven, the rotating cylinder body 610 and the rotating nozzle 620 are relatively rotated about the central axis AX with respect to the inner electrode 100 and the outer electrode 400 via the first gear 710 and the second gear 720. Therefore, for example, plasma corresponding to the shape of the workpiece can be irradiated to the workpiece.

[0044] As described above, in the plasma processing apparatus 1 of this embodiment, the rotating cylinder 600 is made of insulating material, so compared with the case where the rotating cylinder 600 is made of conductive material (metal, etc.), the risk of contact with the rotating cylinder 600 is reduced and safety is improved.

[0045] Those skilled in the art will appreciate that the above-described multiple exemplary embodiments are specific examples of the following aspects.

[0046] [Solution 1]

[0047] A plasma processing device, wherein:

[0048] The plasma processing device comprises:

[0049] an inner electrode to which a voltage is applied;

[0050] an electrode holder that holds the inner electrode;

[0051] an outer electrode formed in a cylindrical shape and surrounding the inner electrode and the electrode holder;

[0052] an insulating tube disposed between the inner electrode and the electrode holder and the outer electrode, and surrounding the inner electrode and the electrode holder;

[0053] a rotating cylinder portion, which is made of an insulating material and is formed into a cylindrical shape surrounding the outer electrode and is relatively rotatable with respect to the outer electrode around a central axis of the inner electrode; and

[0054] A driving mechanism rotates the rotating cylinder.

[0055] In this plasma processing apparatus, since the rotating cylinder is made of an insulating material, the risk associated with contact with the rotating cylinder is reduced compared to a case where the rotating cylinder is made of a conductive material (metal or the like).

[0056] [Solution 2]

[0057] The plasma processing apparatus according to claim 1, wherein:

[0058] The plasma processing device further includes a support body for supporting the electrode holder and the outer electrode.

[0059] The electrode holder has:

[0060] a holding body main body which holds the inner electrode and is arranged to penetrate the support body; and

[0061] a block portion connected to the base end portion of the holding body main body,

[0062] The block portion is fixed to the support body from one side in a direction parallel to the central axis.

[0063] The outer electrode is fixed to the support body from the other side in a direction parallel to the central axis.

[0064] [Solution 3]

[0065] The plasma processing apparatus according to claim 2, wherein:

[0066] The insulating tube is sandwiched by the outer electrode and the support body from both sides in a direction parallel to the central axis.

[0067] In this scheme, the position of the insulating tube is determined, so the position where plasma is generated is effectively specified.

[0068] [Solution 4]

[0069] The plasma processing apparatus according to claim 1, wherein:

[0070] The driving mechanism comprises:

[0071] motor;

[0072] A first gear connected to an output shaft of the motor; and

[0073] a second gear configured to mesh with the first gear,

[0074] The second gear is arranged to surround the outer electrode.

[0075] The rotating cylinder has a receiving surface for receiving the second gear in a direction parallel to the central axis.

[0076] The second gear is fixed to the rotating cylinder by a fastening member, and the fastening member applies an axial force that presses the second gear toward the receiving surface.

[0077] In this aspect, the second gear is fixed to the rotating cylindrical portion by the fastening member, so that idling of the second gear portion relative to the rotating cylindrical portion is suppressed.

[0078] [Solution 5]

[0079] The plasma processing apparatus according to claim 1, wherein:

[0080] The electrode holder holds the inner electrode so that the front end portion of the inner electrode can move between a retracted position in which the front end surface of the insulating tube is flush with the front end surface of the outer electrode and a protruding position in which the front end surface of the inner electrode is flush with the front end surface of the outer electrode.

[0081] [Solution 6]

[0082] The plasma processing apparatus according to claim 5, wherein:

[0083] The rotating cylinder has:

[0084] an opposing surface that is opposed to the front end surface of the outer electrode; and

[0085] A supply flow path is used to supply gas from the outside of the outer electrode toward between the front end surface and the opposing surface of the outer electrode.

[0086] In this aspect, by supplying gas to the supply flow path, the process gas supplied between the inner electrode and the insulating tube is prevented from flowing outside the outer electrode through between the front end surface and the facing surface of the outer electrode.

[0087] Although the embodiments of the present invention have been described, the embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims, and it is intended to include all changes within the meaning and scope equivalent to the claims.

Claims

1. A plasma processing device, wherein: The plasma processing device comprises: an inner electrode to which a voltage is applied; an electrode holder that holds the inner electrode; an outer electrode formed in a cylindrical shape and surrounding the inner electrode and the electrode holder; an insulating tube disposed between the inner electrode and the electrode holder and the outer electrode, and surrounding the inner electrode and the electrode holder; a rotating cylinder portion, which is made of an insulating material and is formed into a cylindrical shape surrounding the outer electrode and is relatively rotatable with respect to the outer electrode around a central axis of the inner electrode; and A driving mechanism rotates the rotating cylinder.

2. The plasma processing apparatus according to claim 1, wherein: The plasma processing device further includes a support body for supporting the electrode holder and the outer electrode. The electrode holder is fixed to the support body from one side in a direction parallel to the central axis. The outer electrode is fixed to the support body from the other side in a direction parallel to the central axis.

3. The plasma processing apparatus according to claim 2, wherein: The insulating tube is sandwiched by the outer electrode and the support body from both sides in a direction parallel to the central axis.

4. The plasma processing apparatus according to claim 1, wherein: The driving mechanism comprises: motor; A first gear connected to an output shaft of the motor; and a second gear configured to mesh with the first gear, The second gear is arranged to surround the outer electrode. The rotating cylinder has a receiving surface for receiving the second gear in a direction parallel to the central axis. The second gear is fixed to the rotating cylinder by a fastening member, and the fastening member applies an axial force that presses the second gear toward the receiving surface.

5. The plasma processing apparatus according to claim 1, wherein: The electrode holder holds the inner electrode so that the front end portion of the inner electrode can move between a retracted position in which the front end surface of the insulating tube is flush with the front end surface of the outer electrode and a protruding position in which the front end surface of the inner electrode is flush with the front end surface of the outer electrode.

6. The plasma processing apparatus according to claim 5, wherein: The rotating cylinder has: an opposing surface that is opposed to the front end surface of the outer electrode; and A supply flow path is used to supply gas from the outside of the outer electrode toward between the front end surface and the opposing surface of the outer electrode.

Images