Plasma generator and plasma generation method

Abstract

To reduce electrode running costs.SOLUTION: A plasma generation device includes an electrode that turns processing gas into plasma through electrical discharge, a holder that holds the electrode with the tip of the electrode extended, and a fixture that allows the amount of extension of the tip of the electrode from the holder to be adjusted and that fixes the electrode to the holder in a replaceable manner.SELECTED DRAWING: Figure 5

Description

Technical Field

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[0006] , , , , , , The rear end of the electrode is located inside. , ,

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[0001] The present disclosure relates to a plasma generator that plasmatizes a processing gas by discharge between electrodes and the like.

Background Art

[0002] The following patent documents describe a technique for plasmatizing a processing gas by discharge between electrodes.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] This specification aims to reduce the running cost of the electrodes.

Means for Solving the Problems

[0005] To solve the above problems, this specification includes an electrode that plasmatizes a processing gas by discharge, a holder that holds the electrode in a state where the tip of the electrode extends, and a fixture that can adjust the amount of extension of the tip of the electrode from the holder and fixes the electrode to the holder so that the electrode can be replaced. The rear end of the electrode is located inside. A plasma generator and the like having the above components are disclosed. A terminal that contacts the rear end of the electrode inside the holder,

Effects of the Invention

[0007] [Figure 1] This is a diagram showing a plasma device. [Figure 2] This is a perspective view showing the plasma head. [Figure 3] Figure 2 is a cross-sectional view of the plasma head. [Figure 4] This is a magnified cross-sectional view of a plasma head. [Figure 5] This is a magnified cross-sectional view of a plasma head. [Figure 6] This is a cross-sectional view showing a conventional plasma head. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the figures, as embodiments for carrying out the present invention.

[0009] As shown in Figure 1, the plasma apparatus 10 comprises a plasma head 11, a robot 13, and a control box 15. The plasma head 11 is attached to the robot 13. The robot 13 is, for example, a serial link robot (which can also be called an articulated robot), and the plasma head 11 is attached to the tip of the robot 13 via a bracket 12. The plasma head 11 is capable of irradiating plasma gas while attached to the tip of the robot 13. The plasma head 11 is of the robot 13 It can move in three dimensions in response to the drive.

[0010] The control box 15 is primarily composed of a computer and comprehensively controls the plasma apparatus 10. The control box 15 includes a power supply unit 15A that supplies power to the plasma head 11 and a gas supply unit 15B that supplies gas to the plasma head 11. The power supply unit 15A is connected to the plasma head 11 via a power cable (not shown). Based on the control of the control box 15, the power supply unit 15A changes the voltage applied to the electrodes 30 of the plasma head 11 (see Figures 3 to 5).

[0011] Furthermore, the gas supply unit 15B is connected to the plasma head 11 via a gas tube 19. Based on the control of the control box 15, the gas supply unit 15B supplies the reaction gas, which will be described later, to the plasma head 11. The control box 15 controls the gas supply unit 15B and controls the amount of gas supplied from the gas supply unit 15B to the plasma head 11. As a result, the robot 13 operates based on the control of the control box 15 and irradiates the workpiece W placed on the table 17 with plasma gas from the plasma head 11.

[0012] Furthermore, the control box 15 is equipped with an operation unit 15C that has a touch panel and various switches. The control box 15 displays various setting screens and operating status (for example, gas supply status, etc.) on the touch panel of the operation unit 15C. The control box 15 also receives various information through operation input to the operation unit 15C.

[0013] As shown in Figures 2 and 3, the plasma head 11 comprises a housing 20, an internal cable 22, a cable holder 24, a holder mounting device 26, an electrode holder 28, an electrode 30, and the like. The housing 20 is made of a metal material and is generally cylindrical in shape. However, the housing 20 tapers towards the bottom, and the lower end of the housing 20 is conical. Therefore, the lower end of the housing 20 functions as the nozzle 32 of the plasma head 11.

[0014] As shown in FIGS. 4 and 5, the internal cable 22 is disposed inside the housing 20 so as to extend in the axial direction of the housing 20, and is fixed inside the housing 20 by the cable holder 24. The cable holder 24 is generally cylindrical and is fixedly fitted inside the housing 20. And the internal cable 22 is fixedly fitted to the upper end portion inside the cable holder 24. Thereby, the internal cable 22 is fixed inside the housing 20 by the cable holder 24. Note that a gap 36 is formed between the inner peripheral surface of the cable holder 24 and the outer peripheral surface of the internal cable 22 at the lower end portion of the cable holder 24.

[0015] Also, the holder fitting 26 is annular and is fixedly fitted inside the housing 20 below the internal cable 22. A thread groove is formed on the inner peripheral surface of the annular holder fitting 26, and the inner peripheral surface of the holder fitting 26 functions as a threaded hole. Also, a plurality of through holes 38 penetrating in the vertical direction are formed at the outer edge portion of the holder fitting 26.

[0016] Also, the electrode holder 28 is formed of a metal material and is generally cylindrical. However, the electrode holder 28 is tapered downward, and a convex portion 40 is formed at the center of the upper end surface of the electrode holder 28. And a thread is formed on the outer peripheral surface of the convex portion 40. Therefore, by inserting and screwing the convex portion 40 of the electrode holder 28 into the inner peripheral surface functioning as the threaded hole of the holder fitting 26, the electrode holder 28 is detachably attached to the holder fitting 26.

[0017] Also, the inner peripheral surface of the electrode holder 28 has a stepped shape. The upper portion of the inner peripheral surface of the electrode holder 28 is a first inner peripheral surface 50 with a small diameter, and the lower portion of the inner peripheral surface of the electrode holder 28 continuous from the first inner peripheral surface 50 is a second inner peripheral surface 52 with a larger diameter than the first inner peripheral surface 50. The first inner peripheral surface The lower end of the crimp terminal 56 is inserted into 50. The outer diameter of the lower end of the crimp terminal 56 is slightly smaller than the inner diameter of the first inner peripheral surface 50 of the electrode holder 28. Therefore, the crimp terminal 56 is fixed to the first inner peripheral surface 50 of the electrode holder 28 by the hollow bolt 58. Specifically, a lateral hole 60 extending in the radial direction is formed on the upper end side of the electrode holder 28, and the lateral hole 60 communicates with the first inner peripheral surface 50. Then, by screwing the hollow bolt 58 into the lateral hole 60, the crimp terminal 56 is fixed to the first inner peripheral surface 50 of the electrode holder 28. Incidentally, the depth dimension of the lateral hole 60 is longer than the length dimension of the hollow bolt 58. Therefore, the hollow bolt 58 is buried in the lateral hole 60 when screwed into the lateral hole 60 and is not exposed outside from the surface of the electrode holder 28. Further, the crimp terminal 56 extends upward from the upper end of the first inner peripheral surface 50 of the electrode holder 28. And the crimp terminal 56 extending upward from the first inner peripheral surface 50 of the electrode holder 28 and the internal cable 22 are connected by a conductor 62.

[0018] Further, the electrode 30 is in the shape of a round bar, and the outer diameter of the electrode 30 is slightly smaller than the inner diameter of the second inner peripheral surface 52 of the electrode holder 28. And the electrode 30 is inserted into the second inner peripheral surface 52 of the electrode holder 28, and the electrode 30 is fixed to the second inner peripheral surface 52 of the electrode holder 28 by the hollow bolt 66. Specifically, a lateral hole 68 extending in the radial direction is formed on the lower end side of the electrode holder 28, and the lateral hole 68 communicates with the second inner peripheral surface 52. Then, by screwing the hollow bolt 66 into the lateral hole 68, the electrode 30 is fixed to the second inner peripheral surface 52 of the electrode holder 28. Incidentally, the depth dimension of the lateral hole 68 is longer than the length dimension of the hollow bolt 66. Therefore, the hollow bolt 66 is buried in the lateral hole 68 when screwed into the lateral hole 68 and is not exposed outside from the surface of the electrode holder 28. Further, the electrode 30 is fixed to the second inner peripheral surface 52 in a state where the lower end of the electrode 30, that is, the tip, extends a predetermined amount (for example, 3 to 5 mm) from the lower end of the electrode holder 28.

[0019] Furthermore, a gas supply unit 15B is connected to the gap 36 between the inner surface of the cable holder 24 and the outer surface of the internal cable 22 via a gas tube 19 (see Figure 1), and the reaction gas supplied from the gas supply unit 15B flows into the gap 36 between the inner surface of the cable holder 24 and the outer surface of the internal cable 22. The reaction gas then flows downward and flows around the electrode holder 28 through multiple through holes 38 in the holder mounting device 26. The reaction gas then flows downward and also flows around the electrode 30 extending from the lower end of the electrode holder 28, reaching the nozzle 32 of the housing 20. In other words, within the housing 20, the reaction gas flows from the gap 36 between the inner surface of the cable holder 24 and the outer surface of the internal cable 22 through multiple through holes 38 in the holder mounting device 26, around the electrode holder 28 and the electrode 30 extending from the lower end of the electrode holder 28, and reaches the nozzle 32 of the housing 20.

[0020] Oxygen (O2) can be used as the reaction gas (seed gas). The gas supply unit 15B, for example, introduces a mixed gas of oxygen and nitrogen (N2) (for example, dry air (Air)) into the gap 36 between the inner circumferential surface of the cable holder 24 and the outer circumferential surface of the internal cable 22 via a gas tube 19 (see Figure 1). Hereinafter, this mixed gas will be conveniently referred to as the reaction gas, and oxygen will be referred to as the seed gas.

[0021] Furthermore, voltage is applied to the electrode 30 extending from the lower end of the electrode holder 28 from the power supply unit 15A of the control box 15. Specifically, power is supplied from the power supply unit 15A of the control box 15 to the internal cable 22 of the plasma head 11 via the power cable, and power is supplied to the conductor 62 and the crimp terminal 56. Then, the power supplied to the crimp terminal 56 flows to the electrode 30 via the electrode holder 28. In this way, power is supplied to the electrode 30, and a voltage is applied to the electrode 30. At this time, as shown in Figure 5, a pseudo-arc A is generated from the tip of the electrode 30 by the application of voltage to the electrode 30. Since the pseudo-arc A is generated along the flow of the reaction gas, it is generated downward from the tip of the electrode 30 and reaches the tip of the nozzle 32. A pseudo-arc A is generated between the tip of electrode 30 and the tip of nozzle 32. As the reaction gas passes through the pseudo-arc A generated between the tip of electrode 30 and the tip of nozzle 32, the reaction gas is turned into plasma. Therefore, a discharge of pseudo-arc A occurs between the tip of electrode 30 and the tip of nozzle 32, turning the reaction gas into plasma and generating plasma gas.

[0022] With this structure, plasma gas is generated in the plasma head 11 by a discharge between the tip of the electrode 30 and the tip of the nozzle 32, and is ejected from the opening 32A formed at the tip of the nozzle 32. The plasma gas is then ejected from the opening 32A of the nozzle 32, thereby performing plasma treatment on the workpiece W. In the plasma head 11, which generates plasma gas by a discharge between the tip of the electrode 30 and the tip of the nozzle 32 in this way, the tip of the electrode 30 wears down. For this reason, in the plasma head 11, the amount of extension of the tip of the electrode 30 from the electrode holder 28 can be adjusted using the enamel bolt 66, and the electrode 30 can also be replaced.

[0023] More specifically, before the plasma treatment is performed by the plasma head 11, the amount of extension of the tip of the electrode 30 from the electrode holder 28 is adjusted so that the tip of the electrode 30 extends by a predetermined amount (for example, 3 to 5 mm) from the lower end of the electrode holder 28. In other words, the screwing of the enamel bolt 66 into the lateral hole 68 is loosened and adjusted so that the amount of extension of the tip of the electrode 30 from the electrode holder 28 is a predetermined amount (for example, 3 to 5 mm). Then, after the enamel bolt 66 is screwed into the lateral hole 68 and the electrode 30 is fixed inside the electrode holder 28, a reaction gas is supplied to the plasma head 11 and a voltage is applied to the electrode 30, thereby performing the plasma treatment by the plasma head 11. As the plasma treatment is performed in this way, the tip of the electrode 30 gradually wears down, and the amount of extension of the tip of the electrode 30 from the electrode holder 28 decreases.

[0024] In this way, when the amount of the electrode 30's tip extending from the electrode holder 28 falls below a predetermined amount, the amount of the electrode 30's tip extending from the electrode holder 28 is adjusted. That is, the screwing of the enamel bolt 66 into the lateral hole 68 is loosened, and the electrode 30 is lowered so that the amount of the electrode 30's tip extending from the electrode holder 28 becomes the predetermined amount. After the amount of the electrode 30's tip extending from the electrode holder 28 becomes the predetermined amount, the enamel bolt 66 is screwed into the lateral hole 68, fixing the electrode 30 inside the electrode holder 28. This makes it possible to restore the amount of the electrode 30's tip extending to the predetermined amount if it falls below a predetermined amount.

[0025] Furthermore, if the extension amount of the electrode 30 tip is repeatedly adjusted, the electrode 30 will become shorter, making it impossible to fix the electrode 30 with the enamel bolt 66. In other words, for example, if the length of the electrode 30 becomes approximately the same as the length between the lower end surface of the electrode holder 28 and the position where the lateral hole 68 is formed, it will no longer be possible to fix the electrode 30 with the enamel bolt 66 while the tip of the electrode 30 extends beyond the lower end of the electrode holder 28. In this case, when it becomes impossible to fix the electrode 30 with the enamel bolt 66, the electrode 30 is replaced. That is, the screwing of the enamel bolt 66 into the lateral hole 68 is loosened, and the used electrode 30 is removed from the second inner circumferential surface 52 of the electrode holder 28. Then, a new electrode 30 is inserted into the second inner circumferential surface 52 of the electrode holder 28, and the new electrode 30 is fixed inside the electrode holder 28 with the enamel bolt 66.

[0026] Thus, in the plasma head 11, the extension amount of the tip of the electrode 30 is adjusted by the enamel bolt 66, and the electrode 30 is also replaced, thereby reducing the running cost of the electrode as a consumable part compared to conventional plasma heads. In detail, as shown in Figure 6, conventional plasma heads 70 generally have a cylindrical electrode 72. The electrode 72 has a shape that tapers towards the bottom. In addition, an annular electrode mounting device 78 is fixedly fitted inside the housing 76 of the plasma head 70. Screw grooves are formed on the circumferential surface, and the inner circumferential surface of the electrode mounting device 78 functions as a screw hole. In addition, screw threads are formed on the outer circumferential surface of the upper end of the electrode 72. The upper end of the electrode 72 is then inserted into the inner circumferential surface of the electrode mounting device 78, which functions as a screw hole, and screwed in, thereby allowing the electrode 72 to be detachably attached to the electrode mounting device 78.

[0027] Furthermore, a bottomed hole 80 is formed at the upper end of the electrode 72, and a crimp terminal 82 is inserted into this bottomed hole 80. Current is supplied to the crimp terminal 82 via an internal cable (not shown), similar to the plasma head 11. As a result, voltage is applied to the electrode 72 in the plasma head 70, causing a pseudo-arc discharge between the tip of the electrode 72 and the tip of the nozzle 88 of the housing 76, generating plasma gas. Consequently, as the plasma head 70 is used, the tip of the electrode 72 wears down and the electrode 72 becomes shorter. When the length of the electrode 72 becomes shorter than a preset length, the used electrode 72 is removed from the electrode mounting device 78, and a new electrode 72 is attached to the electrode mounting device 78. This makes it possible to discharge properly with the new electrode 72, ensuring the generation of plasma gas.

[0028] Thus, in the conventional plasma head 70, the electrode 72 is replaced when it becomes too short. On the other hand, in the plasma head 11, when the electrode 30 becomes too short, the extension of the tip of the electrode 30 from the electrode holder 28 is adjusted by the enamel bolt 66 without replacing the electrode 30. The electrode 30 is then replaced when it becomes too short to be fixed by the enamel bolt 66. In this way, the plasma head 11 can be used without replacing the electrode 30 until it becomes considerably too short. Therefore, the plasma head 11 can reduce the running cost of electrodes as consumable parts.

[0029] Furthermore, as can be seen by comparing Figure 4 and Figure 6, the volume of the electrode 30 of the plasma head 11 is smaller than the volume of the electrode 72 of the conventional plasma head 70. Therefore, the plasma head 11 can reduce the cost of the electrodes. In addition, because the electrodes of the plasma head 11 are in the shape of a round bar, the processing costs of the electrodes can be reduced, further reducing the cost of the electrodes. And because the cost of the electrodes can be reduced, it becomes possible to change the electrode material to, for example, a more expensive but long-lasting material.

[0030] Furthermore, in the plasma head 70, as shown in Figure 5, a lateral hole 68 is formed on the lower end side of the electrode holder 28, and a mortise bolt 66 for adjusting the extension amount of the electrode 30 is screwed into this lateral hole 68. In other words, the mortise bolt 66 for adjusting the extension amount of the electrode 30 fixes the electrode 30 on the lower end side of the electrode holder 28 in the lateral hole 68. Specifically, the vertical length between the lower end of the electrode holder 28 and the position where the mortise bolt 66 is installed is set to a length dimension of approximately 1 / 4 to 1 / 3 of the length dimension of the electrode 30 when it is not worn, that is, a new electrode 30. As a result, the electrode 30 can be used until its length dimension is approximately 1 / 4 to 1 / 3 of that of a new electrode 30. This makes it possible to use the electrode 30 for a long period of time and reduces the running cost of the electrode as a consumable part.

[0031] Incidentally, the plasma head 11 is an example of a plasma generator. The housing 20 is an example of a housing. The electrode holder 28 is an example of a holder. The electrode 30 is an example of an electrode. The opening 32A of the nozzle 32 is an example of a nozzle. The grub bolt 66 is an example of a fastener.

[0032] In the embodiment described above, the following effects are achieved.

[0033] The plasma head 11 includes an electrode 30 that turns the processing gas into plasma by discharge, an electrode holder 28 that holds the electrode 30 with its tip extended, and a grub bolt 66 that fixes the electrode 30 to the electrode holder 28, allowing adjustment of the amount the tip of the electrode 30 extends from the electrode holder 28 and making the electrode 30 replaceable. Therefore, when the electrode 30 becomes shorter due to the use of the plasma head 11, the electrode 30 can be extended from the electrode holder 28, thereby reducing the running cost of the electrode as a consumable part.

[0034] Furthermore, the electrode 30 is rod-shaped, and the electrode holder 28 is cylindrical in shape, holding the rod-shaped electrode 30 inside. This reduces the processing cost of the electrode 30 and thus the overall cost of the electrode 30.

[0035] Furthermore, the enamel bolt 66 fixes the electrode 30 on the side of the electrode holder 28 from which the electrode 30 extends. This allows the electrode 30 to be used until it becomes considerably shorter, further reducing the running cost of the electrode as a consumable part.

[0036] Furthermore, the plasma head 11 includes a housing 20 that has an electrode 30 inside. By generating a discharge between the tip of the electrode 30 extending from the electrode holder 28 and the tip of the housing 20, the processing gas is converted into plasma, and the plasma head 11 ejects the plasma gas from an opening 32A formed at the tip of the housing 20. This makes it possible to convert the processing gas into plasma with a single electrode, thereby reducing the cost of the plasma head 11.

[0037] Furthermore, the electrode holder 28 is fixed inside the housing 20 at the end of the electrode holder 28 opposite to the end from which the tip of the electrode 30 extends. This ensures that gas flow is maintained around the electrode 30 extending from the electrode holder 28, and by not obstructing the gas flow, it becomes possible to perform discharge by the electrode 30 appropriately.

[0038] Furthermore, the enamel bolt 66 secures the electrode 30 inside the electrode holder 28 without being exposed to the outside from the surface of the electrode holder 28. This ensures the flow of gas around the electrode holder 28 from which the tip of the electrode 30 extends, and by not obstructing the gas flow, it becomes possible to perform discharge by the electrode 30 appropriately.

[0039] In the plasma head 11, an adjustment step is performed to adjust the amount of extension of the tip of the electrode 30 from the electrode holder 28, and a plasmaization step is performed to plasmaize the processing gas by a discharge generated at the tip of the electrode 30 extending from the electrode holder 28. As a result, when the electrode 30 becomes shorter due to the use of the plasma head 11, the electrode 30 can be extended from the electrode holder 28, thereby reducing the running cost of the electrode as a consumable part.

[0040] Furthermore, this disclosure is not limited to the above embodiments, and can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Specifically, for example, in the above embodiments, a grub bolt 66 is used as a fixing device for fixing the electrode 30, but various types of fixing devices can be used as long as they can fix the electrode 30. For example, various types of fixing devices such as collet structures and slotted structures can be used.

[0041] Furthermore, in the above embodiment, a discharge is generated between the tip of the electrode 30 and the tip of the housing 20 to turn the processing gas into plasma. In other words, a discharge is generated by a single electrode 30. On the other hand, a discharge may be generated between multiple electrodes. At least one of these multiple electrodes may be fixed to the electrode holder by a fixing device so that the extension amount of the electrode can be adjusted and replaced.

[0042] Furthermore, the contents of this disclosure are not limited to the dependent relationships described in the claims. For example, in claim 3... This specification also discloses a technical concept in which "the plasma generator described in claim 2" is changed to "the plasma generator described in claim 1 or claim 2." For example, this specification also discloses a technical concept in which "the plasma generator described in any one of claims 1 to 3" in claim 6 is changed to "the plasma generator described in any one of claims 1 to 5." [Explanation of Symbols]

[0043] 11: Plasma head (plasma generator) 20: Housing 28: Electrode holder (holder) 30: Electrode 32A: Opening (outlet) 66: Enamel bolt (fixing device)

Claims

1. An electrode that turns the processing gas into plasma by discharge, A holder that holds the electrode with the tip of the electrode extending outwards and the rear end of the electrode positioned inside, A fixing device that allows adjustment of the amount the tip of the electrode extends from the holder and fixes the electrode to the holder in a replaceable manner, A terminal that contacts the rear end of the electrode inside the holder, A plasma generator equipped with the following features.

2. The electrode is rod-shaped, The plasma generator according to claim 1, wherein the holder is cylindrical in shape and holds the rod-shaped electrode inside.

3. The plasma generator according to claim 2, wherein the fixing device fixes the electrode on the side of the holder from which the electrode extends.

4. The plasma generating device is The housing comprises the aforementioned electrode located inside and a nozzle formed at its tip from which plasma gas is ejected. A plasma generating device according to any one of claims 1 to 3, wherein the processing gas is converted into plasma by discharging an electrical discharge between the tip of the electrode extending from the holder and the tip of the housing.

5. The aforementioned holder is, The plasma generator according to claim 4, wherein the tip of the electrode is fixed inside the housing at the end opposite to the end of the holder from which it extends.

6. The aforementioned fixing device is The plasma generator according to any one of claims 1 to 3, wherein the electrode is fixed inside the holder without being exposed to the outside from the surface of the holder.

7. The holder is The first inner surface and, A second inner surface that communicates with the first inner surface and has a larger inner diameter than the first inner surface, It has, The electrode is held by the holder on the second inner circumferential surface, The plasma generator according to any one of claims 1 to 3, wherein the terminal is held by the holder on the first inner circumferential surface.

8. A plasma generator comprising an electrode that turns a processing gas into plasma by discharge, a holder that holds the electrode with the tip of the electrode extending out and the rear end of the electrode located inside, and a terminal that contacts the rear end of the electrode inside the holder, An adjustment step to adjust the amount of extension of the tip of the electrode from the holder, A plasma generation step is performed in which the processing gas is turned into plasma by a discharge generated at the tip of the electrode extending from the holder, A plasma generation method including [specific details omitted].

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