JP2008147011A - Arc generation device and arc generation method in vacuum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc generation device capable of moving to an arc with a relatively small gas flow rate after start, of reducing the adjustment range of the gas flow rate, and of keeping a stable arc without generating a pulsation phenomenon nor extinguishing the arc. <P>SOLUTION: A region in a certain length range on a gas supply side from a tip of a gas exhaust nozzle 5a within a gas passage of a hollow electrode 4 is formed into a plasma generation region having a small cross section, and the region on the gas supply side is formed into a plasma generation region restraint part having a gas passage cross-sectional area larger than that of the gas exhaust nozzle part, and preventing pressure variation of the plasma generation region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an arc generating apparatus and an arc generating method in a vacuum that can generate an arc in a vacuum such as outer space and perform welding, surface heat treatment or material analysis.

  In GTA (Gas Tungsten Arc) welding, which is conventionally performed in the air, a solid rod-like electrode is applied, a welding gas such as an inert gas is injected around the electrode, and a non-oxidizing atmosphere is formed around the electrode. Arc is generated and welding is performed.

  However, when applying GTA welding by applying a solid rod-like electrode similar to welding in the atmosphere in outer space, etc., the pressure gradient of the arc column decreases because the pressure decreases due to the high vacuum. As a result, the arc becomes unstable and welding becomes difficult. For this reason, it has been considered that in the space, when assembling a structure, it is necessary to depend on a mechanical connection structure other than welding.

  On the other hand, in recent years, as a means for solving arc instability in arc welding in a vacuum, a gas supply device that supplies a welding gas for generating an arc, and a welding gas that is supplied by the gas supply device with a gas passage formed therein Welding in vacuum using a hollow electrode that jets from the tip and a power source that generates a discharge by applying a voltage between the hollow electrode and the work piece and generates an arc in the welding gas An arc welding method has been proposed (see, for example, Patent Documents 1 and 2).

According to this method, since welding gas is jetted into the workpiece through the hollow electrode, plasma can be generated inside the electrode to perform arc welding in vacuum. Thus, in the case of arc welding that is possible with a hollow electrode in a vacuum, the arc length can be increased by making the distance between the electrode and the workpiece to be welded much longer than the GTA in atmospheric pressure. Yes, it is expected that a long arc length of approximately 10 mm will be used because the strength of the arc is strong and efficient.
JP-A-7-185801 JP 2003-170273 A

  When a strong spark is generated by increasing the current at the time of start-up, in the case of a thin plate, the spark may be burned out. On the other hand, at a low welding current value in the case of welding a thin plate or the like, it becomes possible to shift to a welding arc only with a very low probability as the degree of vacuum increases.

  There is also a large difference depending on the type of welding gas used. For example, the ionization voltage of Ar gas is 15.8 eV, whereas the ionization voltage of He gas is 24.6 eV, which is a large value. This means that a large amount of energy is required in He gas to become a welding arc. That is, the He gas is unlikely to become a welding arc.

  As a conventional method for dealing with such circumstances, the welding gas flow rate at the time of arc generation is increased to about 200 cc / min, and the flow rate is reduced to about 10 to 20 cc / min, which is a target welding flow rate after the welding arc is generated. There is a way to make it.

  However, in order to facilitate the generation of arcs by flowing a large amount of welding gas at the time of arc generation, and reducing the gas flow rate to return to the original gas flow rate at the time of transition to the welding arc, a wide range of welding gas flow regulators are used. Adjustment area is required.

  Furthermore, if the welding gas flow rate is suddenly set to the original low flow rate after the arc starts, a phenomenon of transiently pulsating to a flow rate lower than the set value occurs. In order to prevent this, there is a drawback that work such as gradually decreasing the flow rate occurs.

  The generated welding arc is in a plasma state on the tip side inside the hollow electrode. The hollow electrode is heated to a high temperature by this plasma, and there is a drawback that the plasma generation range in the hollow electrode varies depending on the state of the plasma by the welding current and the heating condition of the electrode. If the plasma generation range fluctuates even at a constant welding current, the plasma intensity is affected, and the penetration amount when applied to welding becomes unstable.

  Moreover, when the plasma generation range becomes excessively large, the plasma pressure in the hollow electrode rises, making it difficult to supply the welding gas and extinguishing the welding arc. In particular, a gas with a high ionization voltage such as He gas has a drawback that it requires a large amount of energy at the time of start-up, so that the plasma pressure in the electrode after the generation of the welding arc is high and it is difficult to maintain the welding arc.

  The present invention has been made in view of such circumstances, and can shift to an arc with a relatively small gas flow rate after starting, and can reduce the adjustment range of the gas flow rate, thereby reducing the pulsation phenomenon and the arc. An object of the present invention is to provide an arc generating apparatus and method in a vacuum which can maintain a stable arc without causing extinction.

  In addition, when applied to welding, the amount of penetration is stable, a stable arc can be maintained, the temperature of the electrode tip can be raised in a short time, and the arc can be started, and ionization such as He gas can be performed. Even with high voltage gas, there is no need to change the gas flow rate at the time of arc starting from the time of welding, eliminating the need for extra operations, efficient and simple operation with simple equipment, and high quality arc welding. An object of the present invention is to provide an arc generating apparatus and method capable of performing the above.

  According to the inventor's study, He gas having a high ionization voltage requires a lot of energy at startup. Specifically, it is conceivable to increase the current at startup or increase the gas density by increasing the gas flow rate. However, once activated, when the current is high or the gas density is high, the internal pressure (plasma pressure) due to gas expansion in the hollow electrode is excessively increased. If the internal pressure exceeds a certain limit, the gas cannot be supplied, the arc is difficult to maintain, and the arc disappears.

  Therefore, after the arc is generated, on the contrary, a high current or a large gas flow rate is disadvantageous for maintaining the arc. Means and methods for solving this conflicting phenomenon have been demanded.

  As a result of various tests and examinations by the inventor, at the start, the hole cross-section at the tip of the electrode is narrowed to increase the gas density so that arcing is easy to occur, and after the arc is generated, the internal pressure does not exceed the limit. It was found that if the length of the narrow cross section is set and the hole cross section at the top is made large, the internal pressure can be controlled and the arc can be maintained with a very small gas flow rate even with He gas having a high ionization voltage.

  Therefore, in order to achieve the above object, in the invention according to claim 1, a gas supply device that supplies a gas for generating an arc, and a gas that has a gas passage inside and is supplied from the gas supply device to the tip portion. A hollow electrode having a gas outlet for ejecting a gas, and a power source for causing a discharge by applying a voltage between the hollow electrode and the object to be processed, and ejecting from the gas outlet of the hollow electrode in a vacuum environment An arc generator that heats the object to be processed by generating an arc in a gas to be processed, wherein the region of the gas passage of the hollow electrode has a certain length range from the tip of the gas outlet to the gas supply side Is a plasma generation region suppression portion that has a small cross-sectional area, and a gas supply side region that has a gas passage cross-sectional area larger than that of the gas jet port and suppresses pressure fluctuations in the plasma generation region. Providing an arc generating apparatus in a vacuum, characterized in that.

  In the invention which concerns on Claim 2, the outer dimension of the front-end | tip part of the said hollow electrode was made smaller than a main-body part, and the axial direction length of this small outer dimension part was set shorter than the length of the plasma generation area of the said hollow electrode. An arc generator in vacuum according to claim 1 is provided.

  According to a third aspect of the present invention, a cylindrical arc coating part is provided at the tip of the hollow electrode, and the inner dimension of the arc coating part is larger than the inner dimension of the plasma generation region and the plasma generation region is suppressed. The arc generator in vacuum according to claim 1 or 2, wherein the setting is smaller than the inner dimension of the part.

  In the invention according to claim 4, a hollow electrode having a gas supply device for supplying a gas for generating an arc, and a gas outlet having a gas passage inside and a gas supplied from the gas supply device at a tip thereof. And a power source for causing a discharge by applying a voltage between the hollow electrode and the object to be processed, and generating an arc in the gas ejected from the gas ejection port of the hollow electrode in a vacuum environment An arc generator for heat-treating an object to be processed, wherein the hollow electrode has an inner electrode and an outer electrode capable of relative movement in the axial direction, and the tip of the inner electrode is at least the tip of the outer electrode A region of a certain length range on the gas supply side from the tip of the gas outlet in the gas passage of the inner electrode is a plasma generation region having a small cross-sectional area, and the gas supply The area larger than the gas passage sectional area of said gas ejection port unit, to provide an arc generating apparatus in a vacuum, characterized in that the said plasma generation area to suppress plasma generation area suppressing unit pressure variation in the.

  According to a fifth aspect of the present invention, the tip of the inner electrode is thinner than the main body over a certain length, and the thermal energy density of the tip received from the arc is higher than that of the main body. An arc generator in vacuum as described is provided.

  In the invention according to claim 6, the second gas passage is formed by opening a cylindrical gap between the inner electrode and the outer electrode, and the second gas outlet is formed at the tip of the outer electrode. Of the two gas passages, a region within a certain length range on the gas supply side from the tip of the second gas outlet is a plasma generation region having a small cross-sectional area, and further, the gas supply cross-sectional area is the gas supply side region. The arc generator in vacuum according to claim 5, wherein the plasma generation region suppression unit is configured to suppress a pressure fluctuation in the plasma generation region that is larger than the two gas outlets.

  In the invention which concerns on Claim 7, the hollow electrode which has the gas supply apparatus which supplies the gas for arc generation | occurrence | production, and the gas nozzle which ejects the gas supplied from the said gas supply apparatus in the front-end | tip part while having a gas passage inside And a power source for causing a discharge by applying a voltage between the hollow electrode and the object to be processed, and generating an arc in the gas ejected from the gas ejection port of the hollow electrode in a vacuum environment An arc generator for heat-treating an object to be processed, wherein the hollow electrode has an inner electrode and an outer electrode capable of relative movement in the axial direction, and the tip of the inner electrode is at least the tip of the outer electrode A region of a certain length range on the gas supply side from the tip of the gas outlet in the gas passage of the outer electrode as a plasma generation region having a small cross-sectional area, and further supplying the gas The area larger than the gas passage sectional area of said gas ejection port unit, to provide an arc generating apparatus in a vacuum, characterized in that the said plasma generation area to suppress plasma generation area suppressing unit pressure variation in the.

  In the invention which concerns on Claim 8, the arc generator in a vacuum in any one of Claim 1 thru | or 7 which provided the cooling device on the outer peripheral surface of the said electrode so that a movement along an axial direction was provided.

  In the invention according to claim 9, by using the arc generator according to any one of claims 4 to 8, the plasma generated by supplying different gases to the gas passages of the inner electrode and the outer electrode, respectively. Provided is a method for generating an arc in a vacuum characterized by adjusting.

  According to a tenth aspect of the present invention, there is provided an arc generation method in a vacuum characterized in that welding, surface heat treatment or material analysis is performed using the arc generation apparatus according to any one of the fourth to eighth aspects. To do.

  According to the present invention, it is possible to maintain a stable arc by controlling the region where the generated arc becomes plasma, and in a short time by reducing the wall thickness and thus the volume of the tip of the hollow electrode for generating the arc. The temperature at the tip of the electrode can be raised to start the arc, and the transition to the arc is facilitated. Even in high vacuum and gas with high ionization voltage such as He, it is not necessary to change the gas flow rate at the time of arc starting from welding, etc. Good quality welding and the like can be obtained without requiring operation.

  Embodiments of an arc generating apparatus and an arc generating method in vacuum according to the present invention will be described below with reference to the drawings.

[First Embodiment (FIGS. 1 to 3)]
In 1st Embodiment of this invention, it is an arc generator which heat-processes a to-be-processed object by generating an arc in the gas which ejects from the gas jet nozzle of a hollow electrode in a vacuum environment, Comprising: Gas passage of a hollow electrode Among them, a region of a certain length range on the gas supply side from the tip of the gas outlet is a plasma generation region having a small cross-sectional area, and further, a gas passage cross-sectional area of the region on the gas supply side is larger than that of the gas outlet, An arc generator in a vacuum that serves as a plasma generation region suppression unit that suppresses pressure fluctuations in the plasma generation region will be described.

  FIG. 1 is a configuration diagram illustrating the entire arc generator in vacuum according to the present embodiment. As shown in FIG. 1, the arc generator 1 of the present embodiment includes a gas supply device 2 that supplies a gas a for generating an arc. The gas supply device 2 is configured, for example, in a casing shape, and has a gas introduction portion 2a having a lateral opening that receives supply of a gas a from a gas supply source (not shown), and an inner portion of the gas introduction portion 2a than the hole cross section. And a gas receiving portion 2b having a larger cross section. The gas receiving portion 2b protrudes downward by a certain length, and a hollow electrode support hole 2d is opened downward at the lower end of the protruding portion 2c.

  A hollow electrode 4 is connected to the hollow electrode support hole 2 d of the gas supply device 2 through a seal member 3 while maintaining airtightness. In the following example, a case where the hollow electrode 4 is a tungsten electrode will be described.

  The hollow electrode 4 is, for example, a circular tube that is open at both ends in the axial direction (the vertical direction in the figure), and is held by the gas supply device 2. And the internal hole formed along the axial direction of the hollow electrode 4 becomes the gas passage 5 for circulating gas.

  The gas a supplied from the gas supply device 2 is passed through the gas passage 5, and the gas a is jetted downward from the gas outlet 5 a at the tip (lower end) of the hollow electrode 4. Further, an electrode moving mechanism, for example, an elevating mechanism 6 is connected to the gas supply device 2 and the hollow electrode 4, and the elevating mechanism 6 allows the tip of the hollow electrode 4 to move up and down toward the workpiece 7. ing.

  Furthermore, between the hollow electrode 4 and the object 7 to be processed, a power source 8 is connected via a wire 9 for applying a voltage to the hollow electrode 4 and causing discharge to generate an arc in the gas a.

  In such a configuration, in the gas passage 5, a region within a certain length range on the gas supply side from the tip of the gas outlet 5 a is a plasma generation region S 1 having a small cross-sectional area, and the region on the gas supply side is the gas passage. The cross-sectional area is larger than that of the gas outlet, and the plasma generation region suppression unit S2 is configured to suppress pressure fluctuations in the plasma generation region S1.

  That is, the diameter of the gas passage 5 of the hollow electrode 4 is not constant in the entire length direction (vertical direction), and the diameter (d1) of the tip portion that is the plasma generation region S1 is small, and the gas that is the plasma generation region suppression unit S2 The supply side diameter (d2) is large.

  As for the outer diameter, which is the outer dimension of the hollow electrode 4, the outer diameter (D1) of the front end portion (lower end portion) 4a of the hollow electrode 4 is the outer diameter of the main body portion 4b (step 4c). It has a smaller diameter than D2). The inner and outer lengths and diameters of the distal end portion 4a of the hollow electrode 4 are set in accordance with a processing apparatus such as a welding apparatus to be applied and a thermal energy density necessary for processing conditions such as welding conditions. The external dimensions when the hollow electrode 4 is a polygon are the distance between the opposing intersections, the distance between the opposing faces, and the distance between the opposing intersections and the faces. In the case of an equilateral triangle, the outer dimension is the height from the bottom. Yes, in the case of a square, it is the length of one side or the length of a diagonal line.

  Further, the distal end portion (lower end portion) 4a of the hollow electrode 4 is made thinner than the main body portion 4b over a certain length in a range shorter than the length of the portion having a small gas passage cross-sectional area, and is received from the arc due to the small volume. The thermal energy density of the tip portion 4a is higher than that of the main body portion 4b.

  That is, the outer diameter D1 of the distal end portion of the hollow electrode 4 is made smaller than the outer diameter D2 of the main body portion, and the axial length S1 of this small diameter portion is set shorter than the length S2 of the plasma generation region of the hollow electrode 4. Is.

  Next, based on the above configuration, a method for generating an arc in vacuum will be described using a welding method as an example. By using the arc generator 1 described above, in this embodiment, the lifting / lowering mechanism is brought into contact with the hollow electrode 4 and the workpiece 7 by the lifting / lowering mechanism 6 while flowing a small amount of gas, and the power supply 8 is activated. The hollow electrode 4 is pulled up by 6. A spark is generated at the moment when the hollow electrode 4 is separated from the workpiece 7, and a method of transferring the energy of the spark at this time to the gas and transferring to the welding arc, that is, a touch start method can be applied.

  In this method, after the hollow electrode 4 is brought into contact with the workpiece 7, the lifting / lowering mechanism 6 pulls up the hollow electrode 4 by 1 to 2 mm with the power supply 8 being output. Since the hollow electrode 4 and the workpiece 7 are separated in the energized state, an arc due to spark is generated between the hollow electrode 4 and the workpiece 7. Since the tip portion 4a of the hollow electrode 4 is a thin structure and is located at a short distance from the object 7 to be processed, it is heated by Joule heat generated by the generated arc and current of the spark, and the small-diameter tip portion 4a of the hollow electrode 4 is heated. The temperature rises instantly. Thereby, as the temperature of the hollow electrode 4 increases, electron emission from the hollow electrode 4 becomes more active, and an arc tends to occur.

  Further, as the temperature rises, the supplied gas a is heated to plasma by the tip portion 4a of the electrode 4 serving as a high temperature portion, and is transferred to an arc. After the transition to the arc, the distance between the hollow electrode 4 and the workpiece 7 is raised to the interval of the welding condition of, for example, about 10 mm by the lifting mechanism 6 and the arc length is extended to move to a strong region where the arc can be used efficiently. And can be welded.

  Here, when the gas passage 5 has a constant cross-sectional area and is configured in the electrode axial direction, a region in which the upper side of the hollow electrode 4 is gradually raised by the heat generated by plasma at the tip of the hollow electrode 4 and is converted into plasma. To spread. This plasma generation region varies from time to time in a range where energy balance is achieved, depending on the state of the hollow electrode 4 and the disturbance condition. That is, the intensity of the plasma fluctuates, and as a result, the heat source fluctuates, resulting in a problem in welding quality. Further, when using a gas with a high ionization voltage such as He gas, a large amount of energy is required at the time of starting the arc, so it is necessary to make the starting current higher than in the case of Ar gas. When the plasma is generated by starting with a high current, the pressure of the plasma in the hollow electrode 4 becomes high. When this pressure exceeds a certain value, it becomes difficult to supply the gas a and the plasma disappears.

  On the other hand, according to the present embodiment, since the gas passage cross-sectional area of the hollow electrode 4 is reduced only at the tip, the gas density is reached when the plasma generation region reaches a wide portion even if the plasma generation region is widened. And the plasma generation region beyond this can be suppressed.

  That is, the plasma generation region S1 can be fixed in a range where the gas passage 5a at the tip of the hollow electrode 4 is small. This suppresses fluctuations in the intensity of the generated plasma, and even in a gas with a high ionization voltage such as He gas, an arc can be easily generated even with a very small gas flow rate, enabling stable welding and the like. Thus, processing such as high-quality welding can be performed with a simple apparatus.

  As described above, according to the welding apparatus and the welding method of the present embodiment, it is not necessary to adjust the supply amount of the gas a in the middle, and it is supplied at a constant amount. This adjustment range is unnecessary, and pulsation of the flow rate due to the necessity of adjusting the flow rate in the middle can also be eliminated.

  Further, even with a gas having a high ionization voltage such as He gas that is difficult to generate an arc, welding or the like can be easily performed with a low current.

  According to the present embodiment, by combining various methods, the gas density at the time of arc generation is increased, and the energy at the time of arc generation is increased by the temperature rise of the tip 4a of the hollow electrode 4 and the gas a in the hollow electrode 4. The level rise becomes remarkable, and the transmission efficiency of the weak spark energy to the gas a can be increased.

  In addition, according to the present embodiment, even under a high vacuum, the gas flow rate at the time of starting the arc is not changed from that at the time of welding, and even a small amount of gas flow rate can be easily transferred to the welding arc, high quality welding, etc. Can be obtained.

  FIG. 2 is an enlarged cross-sectional view showing a different tip configuration of the hollow electrode 4 in the arc generator 1 shown in FIG. 1 as a first modification of the present embodiment.

  In this example, no step is provided at the tip of the hollow electrode 4 and the thickness is large. Since the volume of the hollow electrode 4 is larger than that of the hollow electrode 4 shown in FIG. 1, the thermal energy density received from the arc is low, but a gas with a low ionization voltage is used or the gas flow rate is increased. When the required energy is low as in the case of starting, it can be applied for generating an arc.

  FIG. 3 is an enlarged cross-sectional view showing a different tip configuration of the hollow electrode 4 in the arc generator 1 shown in FIG. 1 as a second modification of the present embodiment.

  In this example, a cylindrical arc covering portion 10 is integrally provided at the tip of the hollow electrode 4. That is, the inner diameter d3 of the arc covering portion 10 is set to be larger than the inner diameter d1 of the plasma generation region and smaller than the inner diameter d2 of the plasma generation region suppressing portion.

  According to such a configuration, the plasma region generated at the tip of the hollow electrode 4 can be guided to the upper portion having a smaller gas passage cross-sectional area, and the gas density can be further increased to obtain strong plasma.

[Second Embodiment (FIGS. 4, 5A, 5B)]
FIG. 4 is a block diagram showing the entire arc generator 1 in vacuum according to the second embodiment of the present invention, and FIGS. Since the basic configuration of the entire apparatus is substantially the same as that of the first embodiment, the same components as those in FIG.

  The present embodiment is different from the first embodiment in that the hollow electrode 4 has an inner electrode 11 and an outer electrode 12 that can move relative to each other in the axial direction, and the tip (lower end) of the inner electrode 11 is at least the outer electrode 12. It is in the point which can project and retreat in the axial direction from the front-end | tip part (lower end part).

  Similar to the hollow electrode 4 shown in FIG. 2, the inner electrode 11 is configured such that no step is provided at the tip of the hollow electrode 4 and the wall thickness is large. The outer electrode 12 is formed in a cylindrical shape and is supported by the gas supply device 2 via the seal member 3.

  In the gas passage 5 of the inner electrode 11, a region within a certain length range on the gas supply side from the tip of the gas outlet 5 a is a plasma generation region having a small cross-sectional area, and the region on the gas supply side is a gas passage. It has a large cross-sectional area and is a plasma generation region suppression unit that suppresses pressure fluctuations in the plasma generation region that is larger than the gas outlet 5a.

  In this configuration, when an arc is generated, as shown in FIG. 5 (a), the inner electrode 11 is protruded downward from the tip of the outer electrode 12, the arc is started with a low current, and when the plasma is stabilized, The inner electrode 11 is pulled up to move the plasma generation point to the outer electrode 12 as shown in FIG. In this case, the inner electrode 11 is pulled up to such an extent that the plasma of the outer electrode 12 cannot be transferred.

  According to this embodiment, it is suitable when starting with a low current and using it with a high current, or when a large plasma column with a low plasma density is required.

[Third Embodiment (FIGS. 6, 7A, 7B)]
FIG. 6 is a block diagram showing the whole of the arc generator 1 in vacuum according to the third embodiment of the present invention, and FIGS.

  In the present embodiment, as shown in FIG. 6, the hollow electrode 4 has an inner electrode 11 and an outer electrode 12 that are relatively movable in the axial direction, and the tip end portion (lower end portion) of the inner electrode 11 is at least of the outer electrode 12. The second embodiment is substantially the same as the second embodiment in that it can protrude and retract in the axial direction from the tip (lower end).

  The present embodiment is different from the second embodiment in the configuration of the inner electrode 11. In the present embodiment, the tip (lower end) of the inner electrode 11 is thinner than the main body over a certain length, and the thermal energy density of the tip received from the arc is higher than that of the main body. .

  Specifically, the inner electrode 11 has substantially the same configuration as the hollow electrode 4 shown in FIG. 1 of the first embodiment, and the inner electrode 11 has an outer diameter lower than the outer diameter of the main body portion 4b via a step portion 4c on the outer lower portion. Also has a small diameter.

  When the arc is generated, as shown in FIG. 7A, the inner electrode 11 is protruded downward from the tip of the outer electrode 12, the arc is started with a low current, and the inner electrode 11 is relatively moved when the plasma is stabilized. The plasma generation point is moved to the outer electrode 12 as shown in FIG. In this case, the inner electrode 11 is pulled up to such an extent that the plasma of the outer electrode 12 cannot be transferred.

  According to such a configuration, since the gas passage cross-sectional area of the inner electrode 11 is reduced only at the tip, as in the first embodiment, the plasma generation region is fixed to the gas passage 5a at the tip of the electrode within a small range. It is possible to suppress fluctuations in the intensity of the generated plasma, and it is possible to easily generate an arc with a small gas flow rate even in a gas having a high ionization voltage such as He gas, and the inner electrode 11 is discharged by the outer electrode 12. Since the region is surrounded, stable welding or the like is possible, and high-quality welding or the like can be performed with a simple apparatus.

[Fourth Embodiment (FIGS. 8A, 8B)]
8A and 8B are explanatory views showing the configuration and operation of the arc generator 1 in vacuum according to the present embodiment.

  As shown in these drawings, in the present embodiment, the second gas passage 13 is formed with a cylindrical gap between the inner electrode 11 and the outer electrode 12, and the second gas is formed at the tip of the outer electrode 12. A spout 11a is formed.

  In the second gas passage 13, a region of a certain length range on the gas supply side from the tip of the second gas outlet 11 a is a plasma generation region having a small cross-sectional area, and further, the region on the gas supply side is a gas passage cross-sectional area. Is larger than the second gas ejection port 11a, and serves as a plasma generation region suppression unit that suppresses pressure fluctuations in the plasma generation region.

  By applying the configuration of the present embodiment, for example, by supplying different gases to the gas passages of the inner electrode 11 and the outer electrode 12, the generated plasma is adjusted, and the arc generation method in vacuum is performed.

  As described above, arc starting becomes difficult with a gas having a high ionization voltage. As one of the methods for solving this, the inner electrode 11 that is touch-started at the time of activation is activated using a gas having a low ionization voltage such as Ar gas that is easily arc activated.

  In this case, since the arc is stabilized once the plasma is formed, the inner electrode 11 is pulled up, and a He gas having a high ionization voltage is allowed to flow from the outer electrode 12 to obtain a plasma in a state where both gases are mixed.

  Thereafter, when the supply of the gas having a low ionization voltage from the inner electrode 11 is stopped, it is possible to easily obtain an arc such as He gas which is difficult to start the arc. In addition, when the gas supplied to the inner electrode 11 is not stopped, a mixed gas state is obtained, and characteristics corresponding to the flow rate ratio can be easily obtained.

[Fifth Embodiment (FIGS. 9A, 9B)]
9A and 9B are explanatory views showing the configuration and operation of the arc generator 1 in vacuum according to the present embodiment.

  As shown in these drawings, in the present embodiment, an inner electrode as a hollow electrode 4 having a gas passage 5 inside and having a gas ejection port 5a for ejecting the gas supplied from the gas supply device 2 at the tip. 11 is provided. Then, an arc is generated in the gas ejected from the gas ejection port 11a of the hollow electrode 4 in a vacuum environment to heat the object to be treated.

  In this configuration, the hollow electrode 4 has an inner electrode 11 and an outer electrode 12 that can move in the axial direction, and the tip of the inner electrode 11 can protrude and retract from at least the tip of the outer electrode 12, In the second gas passage 13 of the outer electrode 12, the constant length range from the tip of the gas outlet to the gas supply side is a plasma generation region having a small cross-sectional area, and the cross-sectional area of the channel in the region on the gas supply side. Is larger than the gas outlet 5a, and serves as a plasma generation region suppression unit that suppresses pressure fluctuations in the plasma generation region.

  According to the present embodiment, for example, the plasma generated can be adjusted by supplying different gases to the gas passages of the inner electrode 11 and the outer electrode 12 according to the configuration of each of the above embodiments.

[Sixth Embodiment (FIGS. 10A, 10B)]
10A and 10B are explanatory views showing the configuration and operation of the arc generator 1 in vacuum according to the present embodiment.

  In the present embodiment, an arc generator 1 in a vacuum in which a cooling device is provided on the outer peripheral surface of an electrode so as to be movable in the axial direction will be described. That is, the arc generator 1 of the present embodiment is provided with a cooling device 14 outside the hollow electrode 4, and the cooling device 14 is configured to move up and down along the long axis of the hollow electrode 4.

  And at the time of arc starting, as shown to Fig.10 (a), the cooling device 14 can be pulled up and the trouble in the temperature rise of an electrode front-end | tip can be eliminated.

  Then, after the plasma is stabilized, it moves to the tip side of the hollow electrode 4 as shown in FIG.

  Thereby, the outside of the hollow electrode 4 where the plasma is generated is cooled, and the plasma is self-contracted to increase the density so as not to disappear. Therefore, as a result, a strong arc can be obtained even when the welding current is the same. At this time, if the cooling device 14 is swung up and down, the plasma can be given a pulse-like intensity change, and pulse welding becomes possible.

  According to this embodiment, the arc can be adjusted by temperature adjustment.

[Other Embodiments]
The present invention can be implemented in various aspects in addition to the above embodiment. For example, in addition to welding, it can be applied to generation of arc in a vacuum for performing surface heat treatment or material analysis.

1 is an overall view showing the configuration of a vacuum arc generator according to a first embodiment of the present invention. The fragmentary sectional view which shows the 1st modification of the arc generator in vacuum by 1st Embodiment of this invention. The fragmentary sectional view which shows the 2nd modification of the arc generator in vacuum by 1st Embodiment of this invention. The whole figure which shows the structure of the arc generator in vacuum by 2nd Embodiment of this invention. (A), (b) is operation | movement explanatory drawing of 2nd Embodiment of this invention. The whole figure which shows the structure of the arc generator in vacuum by 3rd Embodiment of this invention. (A), (b) is operation | movement explanatory drawing of 3rd Embodiment of this invention. (A), (b) is explanatory drawing which shows the structure of the arc generator in vacuum by 4th Embodiment of this invention. (A), (b) is explanatory drawing which shows the structure of the arc generator in vacuum by 5th Embodiment of this invention. (A), (b) is explanatory drawing which shows the structure of the arc generator in vacuum by 6th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Arc generator 2 Gas supply apparatus 2a Gas introduction part 2b Gas receiving part 2c Projection part 2d Hollow electrode support hole 3 Seal member 4 Hollow electrode 4a Tip part (lower end part)
4b Main body portion 4c Outer diameter step portion 4d Gas passage step portion 5 Gas passage 5a Gas jet port 6 Lifting mechanism 7 Object to be processed 8 Power source 10 Arc covering portion 11 Inner electrode 11a Gas jet port 12 Outer electrode 13 Second gas passage a Gas

Claims (10)

A gas supply device for supplying a gas for generating an arc, a hollow electrode having a gas passage inside and a gas outlet for ejecting the gas supplied from the gas supply device at the tip, and the hollow electrode and the object to be processed And a power source for generating a discharge by applying a voltage to the object, and generating an arc in the gas ejected from the gas ejection port of the hollow electrode in a vacuum environment to heat the object to be treated An arc generator, wherein a region of a certain length on the gas supply side from the tip of the gas ejection port in the gas passage of the hollow electrode is a plasma generation region having a small cross-sectional area, and further the region on the gas supply side An arc generator in vacuum characterized in that the gas passage cross-sectional area is larger than that of the gas jet port, and the plasma generation zone suppression unit suppresses pressure fluctuations in the plasma generation zone. 2. The vacuum according to claim 1, wherein the outer dimension of the tip of the hollow electrode is made smaller than that of the main body, and the axial length of the small outer dimension is set shorter than the length of the plasma generation region of the hollow electrode. Arc generator. A cylindrical arc coating part is provided at the tip of the hollow electrode, and the inner dimension of the arc coating part is set to be larger than the inner dimension of the plasma generation area and smaller than the inner dimension of the plasma generation area suppression unit. The arc generator in vacuum according to claim 1 or 2. A gas supply device for supplying a gas for generating an arc, a hollow electrode having a gas passage inside and a gas outlet for ejecting the gas supplied from the gas supply device at the tip, and the hollow electrode and the object to be processed And a power source for generating a discharge by applying a voltage to the object, and generating an arc in the gas ejected from the gas ejection port of the hollow electrode in a vacuum environment to heat the object to be treated An arc generator, wherein the hollow electrode has an inner electrode and an outer electrode capable of relative movement in the axial direction, and the tip of the inner electrode can protrude and retract at least from the tip of the outer electrode, In the gas passage of the inner electrode, a region having a certain length range from the tip of the gas outlet to the gas supply side is a plasma generation region having a small cross-sectional area, and the region on the gas supply side is a gas passage cross-sectional area. The greater the gas ejection port part, arc generation system in a vacuum, characterized in that the suppressing plasma generation area suppressing unit pressure variation in the plasma generation area. The arc generating device in vacuum according to claim 4, wherein the tip end portion of the inner electrode is thinner than the main body portion over a certain length so that the thermal energy density of the tip portion received from the arc is higher than that of the main body portion. . A cylindrical gap is formed between the inner electrode and the outer electrode to form a second gas passage, and a second gas outlet is formed at the tip of the outer electrode. A region of a certain length range on the gas supply side from the tip of the two gas injection ports is a plasma generation region having a small cross-sectional area, and a gas supply cross-sectional area of the gas supply side region is larger than that of the second gas injection port part. The arc generating device in vacuum according to claim 5, wherein the plasma generating region suppressing unit is configured to suppress pressure fluctuation in the plasma generating region. A gas supply device for supplying a gas for generating an arc, a hollow electrode having a gas passage inside and a gas outlet for ejecting the gas supplied from the gas supply device at the tip, and the hollow electrode and the object to be processed And a power source for generating a discharge by applying a voltage to the object, and generating an arc in the gas ejected from the gas ejection port of the hollow electrode in a vacuum environment to heat the object to be treated An arc generator, wherein the hollow electrode has an inner electrode and an outer electrode capable of relative movement in the axial direction, and the tip of the inner electrode can protrude and retract at least from the tip of the outer electrode, In the gas passage of the outer electrode, a region having a certain length range from the tip of the gas outlet to the gas supply side is a plasma generation region having a small cross-sectional area, and the region on the gas supply side is a gas passage cross-sectional area. The greater the gas ejection port part, arc generation system in a vacuum, characterized in that the suppressing plasma generation area suppressing unit pressure variation in the plasma generation area. The arc generator in vacuum according to any one of claims 1 to 7, wherein a cooling device is provided on the outer peripheral surface of the electrode so as to be movable along the axial direction.   A vacuum characterized in that the generated plasma is adjusted by supplying different gases to the gas passages of the inner electrode and the outer electrode using the arc generator according to any one of claims 4 to 8. Inside arc generation method. An arc generating method in a vacuum, wherein welding, surface heat treatment or material analysis is performed using the arc generating apparatus according to claim 4.

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