Arc Treatment System

Abstract

To provide an arc-processing system that can generate arc, while suppressing an adverse effect on an instrument linked to a member to be processed.SOLUTION: An arc-processing system A1 comprises: an external cylindrical nozzle 125 in which a gas circulation space 125a in which an unconsumed electrode 123 is arranged and a gas jet opening 125b communicating with the gas circulation space 125a are formed; a conductive part 14 for ionization arranged in the external cylindrical nozzle 125; a first power supply circuit 31 that applies voltages for arc-processing to the unconsumed electrode 123 and to a member W1 to be processed; and a second power supply circuit 32 that applies AC voltages to the unconsumed electrode 123 and to the conductive part 14 for ionization. When AC voltages are applied to the conductive part 14 for ionization and the unconsumed electrode 123 by the second power supply circuit 32, a gas in the gas circulation space 125a is ionized by an electrical field caused by a potential difference between the conductive part for ionization and the unconsumed electrode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to arc handling systems. [Background technology]

[0002] A method for treating a workpiece using an arc has been known (see, for example, Patent Document 1). The arc treatment system described in the document includes a non-consumable electrode, a nozzle, an ionization conductive part, and a power supply circuit. The nozzle is formed with a gas flow space in which the non-consumable electrode is disposed and a gas ejection opening communicating with the gas flow space. The ionization conductive part is disposed in the nozzle. The ionization conductive part is electrically connected to the workpiece via a resistor. At the start of arc treatment, the power supply circuit applies an initial voltage between the non-consumable electrode and the workpiece. The initial voltage is a high value (e.g., a time-averaged absolute value) of, for example, 10 kV to 20 kV, and has a high frequency of 1 MHz to 2 MHz. When the power supply circuit applies the initial voltage between the non-consumable electrode and the workpiece, an electric field is generated in the region between the ionization conductive part and the non-consumable electrode, and this electric field ionizes the gas in the gas flow space. The ionized gas is ejected between the non-consumable electrode and the workpiece. As a result, the generation of an arc between the non-consumable electrode and the workpiece is promoted, and the probability of an arc being generated (the probability of an arc being successfully started) is improved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-140882 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, a high-frequency voltage is applied to the workpiece as a starting voltage. When the high-frequency voltage applied to the workpiece is transmitted via the workpiece to a device connected to the workpiece (such as the control circuit of the device itself or another device), electromagnetic noise caused by the high-frequency noise can cause problems such as malfunction and breakdown of the device. Note that the higher the frequency of the high-frequency voltage, the greater the adverse effects of electromagnetic noise can be.

[0005] The present disclosure has been devised in consideration of the above circumstances, and its purpose is to provide an arc treatment system that is capable of generating an arc while suppressing adverse effects on equipment connected to the workpiece. [Means for solving the problem]

[0006] The arc treatment system of the present disclosure comprises a gas flow space in which a non-consumable electrode is disposed, an outer cylindrical nozzle having a gas ejection opening communicating with the gas flow space, an ionization conductive part disposed in the outer cylindrical nozzle, a first power supply circuit that applies an arc treatment voltage to the non-consumable electrode and a workpiece, and a second power supply circuit that applies an AC voltage to the non-consumable electrode and the ionization conductive part, and when the AC voltage is applied by the second power supply circuit, the gas in the gas flow space is ionized by an electric field resulting from a potential difference between the ionization conductive part and the non-consumable electrode.

[0007] In a preferred embodiment of the arc treatment system, an insulating member is interposed between the ionization conductive part and the non-consumable electrode, and the AC voltage is applied between the ionization conductive part and the non-consumable electrode across the insulating member, thereby ionizing the gas in the gas flow space by a dielectric barrier discharge.

[0008] In a preferred embodiment of the arc treatment system, the arc treatment system further comprises an inner cylindrical nozzle arranged inside the outer cylindrical nozzle and made of an insulating material, the inner cylindrical nozzle having the non-consumable electrode inserted therethrough and at least a portion of the inner cylindrical nozzle disposed in the gas flow space.

[0009] In a preferred embodiment of the arc treatment system, the ionization conductive part is disposed on the outer surface of the outer cylindrical nozzle, and the outer cylindrical nozzle is interposed as the insulating member between the ionization conductive part and the non-consumable electrode.

[0010] In a preferred embodiment of the arc treatment system, the ionization conductive part is disposed on the inner surface of the outer cylindrical nozzle, and the inner cylindrical nozzle is interposed as the insulating member between the ionization conductive part and the non-consumable electrode. [Effects of the Invention]

[0011] In the arc treatment system of the present disclosure, when the AC voltage is applied by the second power supply circuit, an electric field resulting from a potential difference between the ionization conductive part and the non-consumable electrode ionizes the gas in the gas flow space. With this configuration, no AC voltage is applied to the workpiece during gas ionization, thereby minimizing adverse effects on equipment connected to the workpiece. Furthermore, ionizing the gas promotes arc generation, allowing an arc to be generated without applying a high voltage (e.g., 10 kV to 20 kV) between the non-consumable electrode and the workpiece. Therefore, the arc treatment system of the present disclosure makes it possible to generate an arc while minimizing adverse effects on equipment connected to the workpiece. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an overall configuration of an arc processing system according to an embodiment. [Figure 2] 2 is a cross-sectional view of a torch in the arc handling system of FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 3 is a front view of the torch shown in FIG. 2. [Figure 5] 1 is a timing chart showing an example of a method for generating an arc using an arc processing system. [Figure 6]3 is a cross-sectional view of a torch in an arc processing system according to a first modified example, corresponding to the cross section of FIG. 2. FIG. [Figure 7] 10 is a cross-sectional view of a torch in an arc processing system according to a second modification, corresponding to the cross section of FIG. 2. FIG. [Figure 8] 10 is a cross-sectional view of a torch in an arc processing system according to a third modification, corresponding to the cross section of FIG. 3. FIG. [Figure 9] 10 is a cross-sectional view of a torch in an arc processing system according to a fourth modification, corresponding to the cross section of FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the arc processing system of the present disclosure will be described below with reference to the accompanying drawings. In the following, identical or similar components will be designated by the same reference numerals and redundant description will be omitted.

[0014] FIG. 1 shows the overall configuration of an arc processing system according to an embodiment of the present disclosure. The arc processing system A1 shown in the figure is for performing arc processing on a workpiece W1. The arc processing system A1 performs, for example, welding or melt-cutting on the workpiece W1. Examples of welding on the workpiece W1 include TIG welding and plasma welding. In this embodiment, the arc processing system A1 performs TIG welding. As shown in FIG. 1, the arc processing system A1 includes a robot 1, conductive wires 21 and 22, a power source 3, connection cables 41 and 42, and a gas supply device 5.

[0015] The robot 1 automatically performs TIG welding on a workpiece W1. The workpiece W1 is plate-shaped. The workpiece W1 is made of metal, such as aluminum or a magnesium alloy. The robot 1 includes a manipulator 11, a torch 12, and an ionization conductive part 14.

[0016] The manipulator 11 is, for example, an articulated robot. When the manipulator 11 is driven, the torch 12 can move freely up and down, back and forth, and left and right.

[0017] Fig. 2 is a cross-sectional view of the torch 12 in the arc processing system A1 shown in Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a front view of the torch 12 shown in Fig. 2. Note that Figs. 2 and 4 show a state in which an arc a1 is generated.

[0018] As shown in FIG. 2, the torch 12 includes a torch body 121 , a non-consumable electrode 123 , an outer cylindrical nozzle 125 , a holder 126 , and an inner cylindrical nozzle 129 .

[0019] Torch body 121 has a cylindrical shape. For example, a handle (not shown) that an operator holds in his / her hand is attached to torch body 121. In this embodiment, torch body 121 is made of a conductive material.

[0020] The non-consumable electrode 123 is a rod-shaped conductor. In this embodiment, the non-consumable electrode 123 is made of, for example, tungsten. The non-consumable electrode 123 is, for example, cylindrical with a diameter of approximately 2.4 to 3.2 mm. During welding (arc processing), an arc a1 is generated between the non-consumable electrode 123 and the workpiece W1.

[0021] The outer cylindrical nozzle 125 is fixed to the torch body 121. The outer cylindrical nozzle 125 is cylindrical. An axis Ox of the outer cylindrical nozzle 125 extends along the vertical direction in FIG. 2. The outer cylindrical nozzle 125 surrounds the non-consumable electrode 123 in the circumferential direction T1 (see FIG. 3) of the axis Ox. The dimension of the outer cylindrical nozzle 125 in the horizontal direction in FIG. 2 is, for example, 20 mm to 30 mm. The outer cylindrical nozzle 125 is made of an insulating material. The insulating material constituting the outer cylindrical nozzle 125 may be any material with an appropriate dielectric constant, such as alumina porcelain. Unlike this embodiment, the outer cylindrical nozzle 125 may be made of a conductive member coated with an insulating material. The outer cylindrical nozzle 125 has a gas circulation space 125a and a gas ejection opening 125b. The gas circulation space 125a is formed inside the outer cylindrical nozzle 125. A gas G1 flows through the gas flow space 125a. The gas G1 is an inert gas. Examples of such an inert gas include argon (Ar) and helium (He). The gas outlet 125b communicates with the gas flow space 125a. A non-consumable electrode 123 is disposed in the gas flow space 125a. The gas outlet 125b opens downward in FIG. 2. The gas G1 in the gas flow space 125a is ejected downward in FIG. 2 from the gas outlet 125b. The direction along the axis Ox of the outer cylindrical nozzle 125, in which the gas outlet 125b is open, is defined as a first direction X1. A portion of the non-consumable electrode 123 protrudes from the gas outlet 125b toward the first direction X1. The gas outlet 125b is, for example, circular. The shape of the gas outlet 125b is not limited to a circular shape and may be other shapes, such as a rectangular shape.

[0022] As shown in FIG. 2, the outer cylinder nozzle 125 has a nozzle tip 125d. The nozzle tip 125d is located closest to the first direction X1 of the outer cylinder nozzle 125. The gas ejection opening 125b described above is formed at the nozzle tip 125d. As shown in FIGS. 2 and 3, the outer cylinder nozzle 125 has a nozzle inner surface 125f and a nozzle outer surface 125g. The nozzle inner surface 125f faces the side where the axis Ox of the outer cylinder nozzle 125 is located (the inside of the outer cylinder nozzle 125 in FIGS. 2 and 3). The nozzle inner surface 125f defines a gas flow space 125a. The nozzle outer surface 125g faces the side opposite the side where the axis Ox of the outer cylinder nozzle 125 is located (the outside of the outer cylinder nozzle 125 in FIGS. 2 and 3).

[0023] The holder 126 holds the non-consumable electrode 123. The holder 126 is fixed to the torch body 121. Because the outer cylindrical nozzle 125 is fixed to the torch body 121, the holder 126 is also fixed relative to the outer cylindrical nozzle 125. As shown in FIG. 2, an insertion hole 126b is formed in the holder 126. The non-consumable electrode 123 is inserted through the insertion hole 126b. As shown in FIG. 2, the holder 126 has a holder tip 126a. The holder tip 126a is the end of the holder 126 located on the first direction X1 side. In the example shown in FIG. 2, the holder tip 126a is covered by the inner cylindrical nozzle 129. However, instead of this configuration, the holder tip 126a may be exposed from the inner cylindrical nozzle 129 and face the gas flow space 125a. The insertion hole 126b extends in the second direction X2 from the holder tip 126a.

[0024] As shown in FIG. 2, the holding portion 126 has a collet 127 and a collet body 128. The collet 127 and the collet body 128 are each made of a conductive material. The collet 127 is a cylindrical member. As shown in FIG. 2, an insertion hole 127a is formed in the collet 127. The non-consumable electrode 123 is inserted through the insertion hole 127a. The collet 127 is tapered near the tip 127b. The collet 127 has multiple (e.g., two or four) vertical slots (not shown) extending from the tip 127b along the insertion hole 127a. The collet body 128 is a cylindrical member. As shown in FIG. 2, an insertion hole 128a is formed in the collet body 128. The non-consumable electrode 123 is inserted through the insertion hole 128a. As shown in FIG. 2, a passage for the gas G1 is formed between the collet body 128 and the collet 127. At least one gas ejection hole 128d is formed in collet body 128, as shown in Fig. 2. Gas ejection hole 128d is formed near body tip 128b of collet body 128, as shown in Fig. 2. Gas G1 in the flow path of gas G1 between collet body 128 and collet 127 is ejected from gas ejection hole 128d. Gas G1 ejected from gas ejection hole 128d flows into gas flow space 125a.

[0025] As shown in Fig. 2, collet body 128 is in contact with torch body 121. Collet 127 is pressed in first direction X1 by a pressing member (not shown, arranged above in Fig. 2). This causes the tapered portion of tip 127b of collet 127 to contact the inner surface of collet body 128, tightening the vertical slit in collet 127. This fixes non-consumable electrode 123 in a desired position.

[0026] In this embodiment, the holding portion tip 126a and the outer surface 126c are formed by the collet body 128. The insertion holes 127a and 128a are connected to each other to form the insertion hole 126b.

[0027] The inner tube nozzle 129 is disposed inside the outer tube nozzle 125 and accommodated in the gas flow space 125a. The non-consumable electrode 123 is inserted into the inner tube nozzle 129. The inner tube nozzle 129 is made of an insulating material. The insulating material for the inner tube nozzle 129 may be any material with an appropriate dielectric constant, but an example is alumina porcelain, similar to the outer tube nozzle 125. In the example shown in FIG. 2, the inner tube nozzle 129 covers a portion of the body tip 128b of the collet body 128. The axis of the inner tube nozzle 129 is common with the axis Ox of the outer tube nozzle 125. The inner tube nozzle 129 is disposed at a position sandwiched between the ionization conductive part 14 and the non-consumable electrode 123 in the radial direction of the axis Ox. The radial direction corresponds to the direction extending radially from the axis Ox in the cross section (plan view) shown in FIG. 3.

[0028] As shown in FIG. 2, the inner cylinder nozzle 129 has a nozzle tip 129a. The nozzle tip 129a is located closest to the first direction X1 of the inner cylinder nozzle 129. The nozzle tip 129a protrudes from the outer cylinder nozzle 125 in the first direction X1. The tip 123a of the non-consumable electrode 123 is exposed at the nozzle tip 129a. As shown in FIGS. 2 and 3, the inner cylinder nozzle 129 has a nozzle inner surface 129b and a nozzle outer surface 129c. The nozzle inner surface 129b faces the side where the axis Ox is located (the inner side of the inner cylinder nozzle 129 in FIGS. 2 and 3). The nozzle outer surface 129c faces the side opposite the side where the axis Ox is located (the outer side of the inner cylinder nozzle 129 in FIGS. 2 and 3). As shown in FIGS. 2 and 3, the nozzle inner surface 129b contacts the non-consumable electrode 123. In addition, the region of the nozzle outer surface 129c that is sandwiched between the nozzle outer surface 129c of the inner cylindrical nozzle 129 and the nozzle inner surface 129b of the outer cylindrical nozzle 125 in the radial direction of the axis Ox facing the gas distribution space 125a forms the gas distribution space 125a. Note that in the example shown in Figures 2 and 3, (the nozzle inner surface 129b of) the inner cylindrical nozzle 129 contacts the non-consumable electrode 123, but unlike this example, the inner cylindrical nozzle 129 does not have to contact the non-consumable electrode 123, as in, for example, double-shielded TIG welding.

[0029] The ionization conductive part 14 is disposed in the outer cylindrical nozzle 125. In the example shown in FIGS. 2 and 3, the ionization conductive part 14 is disposed outside the outer cylindrical nozzle 125 and attached to the nozzle outer surface 125g. As shown in FIG. 3, the ionization conductive part 14 is ring-shaped and surrounds the outer cylindrical nozzle 125. The ionization conductive part 14 is made of a conductive material. The ionization conductive part 14 is provided to promote the generation of an arc a1 between the non-consumable electrode 123 and the workpiece W1.

[0030] As shown in FIG. 2, the ionization conductive part 14 is located closer to the first direction X1 than the holding part tip 126a. That is, the ionization conductive part 14 is located lower in FIG. 2 (closer to the workpiece W1) than the holding part tip 126a. The ionization conductive part 14 is located higher in FIG. 2 (farther from the workpiece W1) than the nozzle tip 125d. The dimension L1 (see FIG. 4) of the ionization conductive part 14 in the direction of the axis Ox is, for example, 0.2 mm to 2.0 mm, and more preferably 0.5 mm to 1.5 mm. The dimension L1 is not limited to these numerical examples.

[0031] As shown in FIGS. 2 and 3, an outer cylindrical nozzle 125 and an inner cylindrical nozzle 129 are interposed between the ionization conductive part 14 and the non-consumable electrode 123 in the radial direction of the axis Ox.

[0032] 1, the power supply 3 includes a first power supply circuit 31, a second power supply circuit 32, and a gas flow control circuit 33. The second power supply circuit 32 may exist together with the first power supply circuit 31 as a component of the power supply 3, or may exist as a stand-alone circuit or device outside the power supply 3, separate from the first power supply circuit 31. Alternatively, an integrated power supply circuit may be configured to perform the functions of the first power supply circuit 31 and the second power supply circuit 32.

[0033] The first power supply circuit 31 applies an arc processing voltage between the non-consumable electrode 123 and the workpiece W1 and causes an arc processing current to flow between the non-consumable electrode 123 and the workpiece W1. The arc processing voltage may be either AC or DC, depending on the material of the workpiece W1. The first power supply circuit 31 receives a commercial power supply, such as a three-phase 200V power supply, and performs output control such as inverter control and thyristor phase control. At the start of arc processing, the first power supply circuit 31 applies an arc processing voltage to generate an arc a1. Hereinafter, the arc processing voltage to generate the arc a1 will be referred to as the "start voltage." After the arc a1 is generated, the arc processing voltage decreases to a voltage value sufficient for normal TIG welding, and an arc processing current flows between the non-consumable electrode 123 and the workpiece W1. Hereinafter, the arc processing voltage after the arc a1 is generated will be referred to as the "arc voltage." In an example where the arc processing system A1 performs arc welding, the arc voltage is a welding voltage, and in an example where the arc processing system A1 performs arc cutting, the arc voltage is a cutting voltage. For example, the start voltage is approximately 120V to 160V, and the arc voltage is approximately 10V to 40V. Note that these values ​​are time-averaged absolute values ​​or effective values, for example, when the arc processing voltage is AC. The values ​​of each arc processing voltage (start voltage and arc voltage) are not limited to these numerical examples and may be changed appropriately depending on the specifications of the arc processing system A1. As shown in FIG. 1, the first power supply circuit 31 is electrically connected to the workpiece W1 via a connection cable 41 and to the torch 12 (non-consumable electrode 123) via a connection cable 42.

[0034] The second power supply circuit 32 applies an AC voltage between the non-consumable electrode 123 and the ionization conductive part 14. Hereinafter, the AC voltage applied by the second power supply circuit 32 may be referred to as the "ionization voltage." This AC voltage (ionization voltage) is a high-frequency voltage, and its voltage value (e.g., time-averaged absolute value or effective value) is approximately 10 kV to 20 kV, and its frequency is 1 MHz to 2 MHz. The voltage value and frequency of the AC voltage (ionization voltage) applied by the second power supply circuit 32 are not limited to these numerical examples and may be changed appropriately depending on the specifications of the arc treatment system A1. As shown in FIG. 1, the second power supply circuit 32 is electrically connected to the ionization conductive part 14 via the conductive wire 21 and to the torch 12 (non-consumable electrode 123) via the conductive wire 22 and a portion of the connection cable 42.

[0035] The gas flow rate control circuit 33 controls the flow rate of the gas G1. The gas flow rate control circuit 33 sends a gas flow rate control signal Sg for instructing the flow rate of the gas G1.

[0036] The gas supply device 5 supplies the gas G1 to the inside of the outer cylindrical nozzle 125. The gas supply device 5 supplies the gas G1 based on a gas flow rate control signal Sg from the gas flow rate control circuit 33.

[0037] The connection cable 41 electrically connects the first power supply circuit 31 and the workpiece W1. When the arc treatment system A1 is in use and the workpiece W1 is grounded, the connection cable 41 is maintained at a potential of 0 V. The connection cable 42 electrically connects the first power supply circuit 31 and the non-consumable electrode 123. Power from the first power supply circuit 31 is supplied to the non-consumable electrode 123 via the connection cable 42, torch body 121, collet body 128, and collet 127, in this order.

[0038] Conductive wire 21 electrically connects second power supply circuit 32 and ionization conductive part 14. Conductive wire 22 electrically connects second power supply circuit 32 and torch 12 (non-consumable electrode 123). In the example shown in FIG. 1, conductive wire 22 is connected to connection cable 42, and a portion of connection cable 42 is present in the conductive path from second power supply circuit 32 to non-consumable electrode 123. Alternatively, conductive wire 22 may be directly connected to torch 12 (non-consumable electrode 123).

[0039] Next, a method for generating an arc a1 using the arc processing system A1 will be described with reference to the timing chart of FIG. 5. The horizontal axis of FIG. 5 represents time. The vertical axis of FIG. 5 conceptually represents the state of the gas flow control signal Sg, the output voltage of the second power supply circuit 32, and the output voltage of the first power supply circuit 31. The output voltage of the second power supply circuit 32 is the value (e.g., the time-averaged value or the effective value of the absolute value) of the AC voltage applied to the ionization conductive part 14 and the non-consumable electrode 123. The output voltage of the first power supply circuit 31 is the value (e.g., the time-averaged value or the effective value of the absolute value in the case of an AC voltage) of the voltage applied to the non-consumable electrode 123 and the workpiece W1.

[0040] First, when an arc processing start signal (not shown) is sent to the power supply 3, the gas flow control circuit 33 sends a gas flow control signal Sg to the gas supply device 5 to start the ejection of the gas G1 (time t1). This causes the gas supply device 5 to start supplying the gas G1 to the torch 12 (gas flow space 125a).

[0041] Next, the second power supply circuit 32 applies an ionization voltage between the non-consumable electrode 123 and the ionization conductive part 14 (time t2). The ionization voltage is a high-frequency AC voltage, and its voltage value (for example, the time-averaged value of the absolute value or the effective value) is very large, for example, 10 kV to 20 kV, and its frequency is 1 MHz to 2 MHz.

[0042] When the second power supply circuit 32 applies an ionization voltage (high-frequency AC voltage) between the non-consumable electrode 123 and the ionization conductive part 14, an electric field is generated in the region between the non-consumable electrode 123 and the ionization conductive part 14 due to the potential difference between the non-consumable electrode 123 and the ionization conductive part 14. That is, an electric field is generated in the gas distribution space 125a due to the potential difference between the non-consumable electrode 123 and the ionization conductive part 14. This electric field generates a discharge in the gas distribution space 125a, ionizing the gas G1 in the gas distribution space 125a (turning it into plasma). In the arc treatment system A1, the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129, each made of an insulating material, are interposed between the non-consumable electrode 123 and the ionization conductive part 14. Therefore, the discharge generated in the gas distribution space 125a is a dielectric barrier discharge. A dielectric barrier discharge is also called a silent discharge because it does not generate excessive discharge noise, unlike a spark discharge. Therefore, in the arc treatment system A1, an ionization voltage is applied between the non-consumable electrode 123 and the ionization conductive part 14 by the second power supply circuit 32 to generate a dielectric barrier discharge in the gas flow space 125a, and the gas G1 in the gas flow space 125a is ionized by the dielectric barrier discharge.

[0043] The gas G1 ionized in the gas flow space 125a is released from the gas ejection opening 125b toward the side where the workpiece W1 is located (the first direction X1 side). As a result, the ionized gas G1 (plasma-converted gas G1) is released near the tip 123a of the non-consumable electrode 123, creating a state in which discharge is likely to occur near the tip 123a of the non-consumable electrode 123. In other words, generation of an arc a1 between the non-consumable electrode 123 and the workpiece W1 is promoted.

[0044] Next, the first power supply circuit 31 applies an arc processing voltage (start voltage) between the non-consumable electrode 123 and the workpiece W1 (time t3). This causes a discharge between the non-consumable electrode 123 and the workpiece W1, generating an arc a1. The start voltage output by the first power supply circuit 31 is, for example, about 120 V to 160 V, which is sufficiently lower than the ionization voltage. The distance d1 (see FIG. 2) between the tip 123a of the non-consumable electrode 123 and the workpiece W1 is, for example, about 3 mm to 8 mm. In experiments conducted by the inventors of the present application, for example, an arc a1 was successfully generated when a start voltage of 160 V was applied and the distance d1 was 5.5 mm. It is preferable that the timing at which the first power supply circuit 31 starts applying the starting voltage is after a period of time (for example, the period from time t2 to time t3) has elapsed since the second power supply circuit 32 applied the ionization voltage (AC voltage) so that the gas G1 in the gas flow space 125a can be sufficiently ionized, but it may also be the same as the timing at which the second power supply circuit 32 starts applying the ionization voltage.

[0045] When an arc a1 is generated between the non-consumable electrode 123 and the workpiece W1, the arc processing voltage drops to a voltage value (arc voltage value) at which normal TIG welding can be continued (time t4). Then, the desired arc processing (welding or cutting) is performed by the arc processing system A1. During arc processing (after the arc a1 is generated), the arc processing voltage (arc voltage) output by the first power supply circuit 31 is lower than the start voltage, for example, approximately 10 V to 40 V.

[0046] The arc processing system A1 has the following functions and effects.

[0047] In the arc processing system A1, when an AC voltage (ionization voltage) is applied by the second power supply circuit 32, an electric field resulting from the potential difference between the ionization conductive part 14 and the non-consumable electrode 123 ionizes the gas G1 in the gas flow space 125a. With this configuration, no AC voltage is applied to the workpiece W1 to ionize the gas G1, thereby minimizing adverse effects on equipment connected to the workpiece W1. Furthermore, ionizing the gas G1 promotes the generation of the arc a1, allowing the arc a1 to be generated without applying a high voltage (e.g., 10 kV to 20 kV) between the non-consumable electrode 123 and the workpiece W1. For example, in the arc processing system A1, the arc processing voltage (start voltage) for generating the arc a1 is approximately 120 V to 160 V, which is significantly lower than the conventional configuration (10 kV to 20 kV). Therefore, the arc processing system A1 can generate the arc a1 while suppressing adverse effects on devices connected to the workpiece W1.

[0048] In the arc processing system A1, an insulating member is interposed between the ionization conductive part 14 and the non-consumable electrode 123. In the example shown in FIG. 2, this insulating member is the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129. With this configuration, the gas G1 in the gas flow space 125a is ionized by a dielectric barrier discharge. Therefore, the arc processing system A1 can suppress the occurrence of a spark discharge between the non-consumable electrode 123 and the ionization conductive part 14. The ionization conductive part 14 may be located anywhere between the non-consumable electrode 123 and the insulating member (the outer cylindrical nozzle 125 or the inner cylindrical nozzle 129 in this embodiment) as long as there is no part at the same potential as the non-consumable electrode 123. However, if the creeping distance between the ionization conductive part 14 and the non-consumable electrode 123 is too short, a dielectric breakdown may occur between them, potentially generating an arc (different from the arc a1). Therefore, for example, if the ionization voltage is 15 kV, the creepage distance between the ionization conductive part 14 and the non-consumable electrode 123 should be 15 mm or more. The creepage distance between the ionization conductive part 14 and the non-consumable electrode 123 at which breakdown is suppressed correlates with the ionization voltage applied by the second power supply circuit 32, so the higher the ionization voltage, the longer the creepage distance should be. For example, when the creepage distance is D [mm] and the ionization voltage is V [V], the creepage distance should be set so that D≧k×V−2 (k=0.0015 to 0.0017). Note that the relationship between the creepage distance D and the ionization voltage V is not limited to the above-mentioned formula.

[0049] In the arc processing system A1, the ionization conductive part 14 is disposed on the outer surface (nozzle outer surface 125g) of the outer cylindrical nozzle 125. With this configuration, the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129 are each interposed as insulating members between the ionization conductive part 14 and the non-consumable electrode 123. That is, the ionization conductive part 14 and the non-consumable electrode 123 are disposed with the gas flow space 125a and the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129, which serve as insulating members, sandwiched therebetween. Therefore, the arc processing system A1 can ionize the gas G1 in the gas flow space 125a by a dielectric barrier discharge using the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129 as dielectrics.

[0050] Next, another configuration example of the arc processing system of the present disclosure will be described.

[0051] <First Modification> Fig. 6 shows an arc processing system A2 according to a first modified example. The arc processing system A2 shown in Fig. 6 differs from the arc processing system A1 in that the ionization conductive part 14 is built into the outer cylindrical nozzle 125 of the torch 12. Except for this, each component of the arc processing system A2 is similar to each component of the arc processing system A1 (see Fig. 1).

[0052] In the arc processing system A2, as shown in Fig. 6, the ionization conductive part 14 is embedded in the outer cylindrical nozzle 125 and attached between the nozzle inner surface 125f and the nozzle outer surface 125g in the radial direction of the axis Ox. The ionization conductive part 14 is located outside the nozzle inner surface 125f in the radial direction of the axis Ox and inside the nozzle outer surface 125g in the radial direction of the axis Ox. Thus, the ionization conductive part 14 is covered by the outer cylindrical nozzle 125. In the example shown in Fig. 6, the conductive wire 21 is routed from the nozzle outer surface 125g to the ionization conductive part 14 so as to penetrate the outer cylindrical nozzle 125.

[0053] As with the arc processing system A1, the arc processing system A2 is also capable of generating an arc a1 while suppressing adverse effects on equipment connected to the workpiece W1. Note that in the arc processing system A2, a portion of the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129 are interposed as insulating members between the ionization conductive part 14 and the non-consumable electrode 123. That is, in the arc processing system A2, the portion of the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129 are arranged as insulating members, and a dielectric barrier discharge occurs in the gas flow space 125a, with the portion of the outer cylindrical nozzle 125 and the inner cylindrical nozzle 129 acting as dielectrics.

[0054] <Second Modification> Fig. 7 shows an arc processing system A3 according to a second modification. The arc processing system A3 shown in Fig. 7 differs from the arc processing system A1 in that the ionization conductive part 14 is disposed inside the outer cylindrical nozzle 125. Except for this, each component of the arc processing system A3 is similar to each component of the arc processing system A1 (see Fig. 1).

[0055] In the arc processing system A3, the ionization conductive part 14 is attached to the nozzle inner surface 125f inside the outer cylindrical nozzle 125. The ionization conductive part 14 faces the gas flow space 125a. In the example shown in Fig. 7, the conductive wire 21 is routed from the nozzle outer surface 125g to the nozzle inner surface 125f so as to penetrate the outer cylindrical nozzle 125. However, instead of this configuration, the conductive wire 21 may be routed through the gas ejection opening 125b.

[0056] As with the arc processing system A1, the arc processing system A3 is also capable of generating an arc a1 while suppressing adverse effects on equipment connected to the workpiece W1. In the arc processing system A3, an inner cylindrical nozzle 129 is interposed as an insulating member between the ionization-conductive part 14 and the non-consumable electrode 123. That is, in the arc processing system A3, the inner cylindrical nozzle 129 is disposed as an insulating member, and a dielectric barrier discharge occurs in the gas flow space 125a, with the inner cylindrical nozzle 129 serving as a dielectric. Furthermore, in the arc processing system A3, the inner cylindrical nozzle 129 is interposed as an insulating member between the ionization-conductive part 14 and the non-consumable electrode 123, allowing the ionization-conductive part 14 to be disposed inside the outer cylindrical nozzle 125.

[0057] <Third Modification> Fig. 8 shows an arc processing system A4 according to a third modification. The arc processing system A4 shown in Fig. 8 differs from the arc processing system A1 in that the ionization conductive part 14 is not ring-shaped but includes a plurality of separation parts 141 that are separated from one another. Except for this, each component of the arc processing system A4 is similar to each component of the arc processing system A1 (see Fig. 1).

[0058] In the arc processing system A4, the ionization conductive unit 14 includes a plurality of separation units 141. In the example shown in FIG. 8, the number of separation units 141 is four. The number of separation units 141 may be two, three, or five or more, instead of four. The separation units 141 are arranged at different positions along the circumferential direction T1 of the axis Ox of the outer cylindrical nozzle 125. To evenly separate the gas G1 in the gas flow space 125a, the separation units 141 are preferably arranged at equal intervals along the circumferential direction T1. For example, in a configuration in which the ionization conductive unit 14 includes four separation units 141, as in the arc processing system A4, the four separation units 141 are arranged at 90-degree intervals around the axis Ox, as shown in FIG. 8.

[0059] In the arc processing system A4, as in the arc processing system A1, it is possible to generate the arc a1 while suppressing adverse effects on devices connected to the workpiece W1.

[0060] In the third modified example, the arc processing system A1 is provided with an ionization-use conductor 14 including a plurality of separators 141 instead of the ring-shaped ionization-use conductor 14. Similarly, the arc processing systems A2 and A3 according to the first and second modified examples may also be provided with an ionization-use conductor 14 including a plurality of separators 141 instead of the ring-shaped ionization-use conductor 14.

[0061] <Fourth Modification> Fig. 9 shows an arc processing system A5 according to a fourth modification. The arc processing system A5 shown in Fig. 9 differs from the arc processing system A1 in that the torch 12 does not include an inner cylindrical nozzle 129. Except for this, each component of the arc processing system A5 is similar to each component of the arc processing system A1 (see Fig. 1).

[0062] In the arc handling system A5, the torch 12 does not include the inner cylindrical nozzle 129, so the non-consumable electrode 123 faces the gas flow space 125a.

[0063] As with the arc processing system A1, the arc processing system A5 is also capable of generating an arc a1 while suppressing adverse effects on equipment connected to the workpiece W1. Note that in the arc processing system A5, an outer cylindrical nozzle 125 is interposed as an insulating member between the ionization conductive part 14 and the non-consumable electrode 123. That is, in the arc processing system A5, the outer cylindrical nozzle 125 is disposed as an insulating member, and a dielectric barrier discharge occurs in the gas flow space 125a, with the outer cylindrical nozzle 125 serving as a dielectric.

[0064] In the fourth modified example, an example is shown in which the torch 12 in the arc processing system A1 does not have an inner cylindrical nozzle 129, but in each of the arc processing systems A2 and A4 according to the first and third modified examples, the torch 12 may not have an inner cylindrical nozzle 129.

[0065] The arc processing system of the present disclosure is not limited to the above-described embodiment, and the specific configuration of each part of the arc processing system of the present disclosure can be freely designed and modified in various ways. [Explanation of symbols]

[0066] A1 to A5: arc treatment system, G1: gas, W1: member to be treated, 123: non-consumable electrode, 125: outer cylindrical nozzle, 125a: gas flow space, 125b: gas ejection opening, 125f: nozzle inner surface, 125g: nozzle outer surface, 129: inner cylindrical nozzle, 14: ionization conductive part, 31: first power supply circuit, 32: second power supply circuit

Claims

1. a gas flow space in which a non-consumable electrode is disposed, and an outer cylindrical nozzle having a gas ejection opening communicating with the gas flow space; a conductive part for ionization disposed in the outer cylindrical nozzle; a first power supply circuit for applying an arc processing voltage to the non-consumable electrode and the workpiece; a second power supply circuit that applies an AC voltage to the non-consumable electrode and the ionization conductive portion; Equipped with when the AC voltage is applied by the second power supply circuit, an electric field caused by a potential difference between the ionization conductive part and the non-consumable electrode ionizes the gas in the gas flow space, an arc treatment system in which a creepage distance D [m] between the ionization conductive part and the non-consumable electrode along at least the surface of the outer cylindrical nozzle satisfies D≧k×V−2, where V [V] is the voltage applied by the second power supply circuit and k is a coefficient that takes a value between 0.0015 and 0.0017.

2. an insulating member is interposed between the ionization conductive part and the non-consumable electrode; the AC voltage is applied to the ionization conductive part and the non-consumable electrode with the insulating member sandwiched therebetween, whereby the gas in the gas flow space is ionized by a dielectric barrier discharge. The arc handling system of claim 1 .

3. An inner cylindrical nozzle is arranged inside the outer cylindrical nozzle and is made of an insulating material, The arc handling system according to claim 2 , wherein the non-consumable electrode is inserted through the inner cylindrical nozzle, and at least a portion of the inner cylindrical nozzle is disposed in the gas flow space.

4. An arc processing system as described in claim 3, wherein a portion of the inner tube nozzle protrudes through the gas ejection opening to the outside of the outer tube nozzle in the direction in which the inner tube nozzle extends.

5. the conductive portion for ionization is disposed on the outer surface of the outer cylindrical nozzle, 5. The arc processing system according to claim 2, wherein said outer cylindrical nozzle is interposed as said insulating member between said ionization conductive part and said non-consumable electrode.

6. the conductive portion for ionization is disposed on the inner surface of the outer cylindrical nozzle, 5. The arc processing system according to claim 3, wherein the inner cylindrical nozzle is interposed as the insulating member between the ionization conductive part and the non-consumable electrode.

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