JP2005224830A - Plasma welding torch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma welding torch in which the central axes of an electrode and a plasma nozzle are not shifted, and the cooling capacity of the plasma nozzle is high. <P>SOLUTION: The plasma welding torch is provided with: an electrode 2 provided at the axial core part of a torch body 1 and generating a main plasma arc in a space with the object to be welded; a plasma nozzle 5 generating a pilot arc in a space with the electrode 2; a heat radiation member 8 provided inside the torch body and into which the nozzle 5 is inserted; a shielding gas cup 12 surrounding the tip part of the nozzle 5 and screwed on the torch body 1; and a gas lens 14 sandwiched between a step part 5b formed on the outer circumferential face of the balance in the nozzle 5 and a step part 12a formed on the inner circumferential face of the tip part in the cup 12. An insertion part to the heat radiation member 8 of the nozzle 5 and the part to be inserted in the heat radiation member 8 into which the insertion part is inserted so as to be internally contacted therewith are conically formed, and the nozzle 5 is inserted into the heat radiation part 8, and the cup 12 is screwed on the torch body 1, thus the positioning of the nozzle 5 to the electrode 2 is performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improved plasma welding torch for performing plasma welding.

  In plasma welding, a main plasma arc when a tungsten electrode is generally discharged as a cathode is constrained by a water-cooled plasma nozzle and a gas flow of plasma gas, thereby generating a highly concentrated high-temperature plasma flow, Welding is performed using the retained energy. A conventional plasma welding torch will be described with reference to FIG.

[Prior art 1]
FIG. 7 is a view showing a plasma welding torch of Prior Art 1 disclosed in Patent Document 1. As shown in FIG. In the figure, a plasma nozzle 16 that restrains the main plasma arc is screwed to the torch body 15 and surrounds the tip of the electrode 2. An insulating guide 17 is provided on the electrode 2. The insulating guide 17 is formed with a plasma gas flow path 17a through which the plasma gas 7 is ejected. The plasma gas 7 is supplied to the plasma gas flow path 17a from a plasma gas supply source (not shown), and a main plasma arc is generated between the electrode 2 and the workpiece.

  Patent Document 1 does not describe a coolant channel for water cooling. However, if the coolant channel for water cooling is provided around the torch body 15 and the plasma nozzle 16 is not cooled by heat conduction, the plasma nozzle 16 is dissolved, so the coolant channel is indispensable. And this concentrated plasma can be used as a heat source for thermal processing such as overlaying, welding, and cutting.

  The plasma welding torch of the prior art 1 shown in FIG. 7 is screwed to the torch body 15 with the plasma nozzle 16 threaded. In plasma welding, if the central axes of the electrode 2 and the plasma nozzle 16 do not coincide with each other with high accuracy, good plasma cannot be obtained, and the life of the plasma nozzle 16 and the electrode 2 is shortened. In screwing, the accuracy of thread cutting is low, and the center axis of the electrode 2 and the plasma nozzle 16 is often shifted, and the plasma nozzle 16 and the electrode 2 are burned out.

  Further, in screwing by threading, the contact area between the torch body 15 and the plasma nozzle 16 is not necessarily large. This is because there are gaps between the valley on the male screw side and the mountain on the female screw side and between the mountain on the male screw side and the valley on the female screw side. Further, since air having a high thermal resistance exists in the gap, the heat conduction of the plasma nozzle 16 is poor, the temperature is likely to rise, and the plasma nozzle 16 is burned out.

[Prior Art 2]
On the other hand, Patent Document 2 discloses a plasma welding torch having a structure in which the plasma nozzle is directly water-cooled in order to prevent burning of the plasma nozzle. The plasma nozzle of the plasma welding torch is fixed to a cap, and the cap is threaded. The cap is screwed to the torch body, so that the plasma nozzle is attached to the torch body.
Therefore, as in the prior art 1 described above, screwing has low accuracy of thread cutting, and often the center axis of the electrode and the plasma nozzle is displaced, resulting in burning of the plasma nozzle and the electrode.

  Further, since the plasma nozzle is directly water-cooled, an O-ring is attached between the plasma nozzle and the cap. This O-ring is a rubber product and is generally vulnerable to heat. Although the plasma nozzle is directly water-cooled, it is exposed to high temperatures, so the use of a heat-sensitive member there should be avoided. In addition, water leakage may occur due to deterioration of the O-ring or failure of screwing. Leakage is not allowed, for example, in the welding of a membrane that stores LNG, and the use of a torch having a structure that is liable to leak must be avoided.

Furthermore, in order to directly cool the plasma nozzle with water, it is necessary to provide a coolant channel inside the plasma nozzle, which increases the shape of the plasma nozzle. As a result, the main body of the torch is enlarged, and problems such as interference of the torch main body with the structure occur in the welding of the narrow portion.
Japanese Utility Model Publication No. 56-126980 Japanese Utility Model Publication 2-87564

As described above, in the plasma welding torch of the prior art 1, the plasma nozzle is threaded and screwed to the torch body. Therefore, in screwing, the accuracy of threading is low, and the center axis of the electrode and the plasma nozzle often shifts, resulting in burning of the plasma nozzle and the electrode.
Further, in screwing by threading, the contact area between the torch body and the plasma nozzle is not necessarily large. Further, since air having a high thermal resistance exists in the gap, the heat conduction of the plasma nozzle is poor, the temperature is likely to rise, and the plasma nozzle is burned out.

  Further, in the plasma welding torch having a structure in which the plasma nozzle of the prior art 2 is directly water-cooled, the plasma nozzle is attached to the torch body through a threaded cap. Therefore, in screwing, the accuracy of threading is low, and the center axis of the electrode and the plasma nozzle often shifts, resulting in burning of the plasma nozzle and the electrode.

  In addition, since the plasma nozzle is directly water-cooled, an O-ring is attached between the plasma nozzle and the cap. Therefore, water leakage may occur due to the deterioration of the O-ring or the failure of screwing. Furthermore, it is necessary to provide a refrigerant flow path inside the plasma nozzle, and the torch main body becomes large, and problems such as interference of the torch main body with the structure occur in the welding of the narrow portion.

  An object of the present invention is to provide a plasma welding torch in which the central axis of the electrode and the plasma nozzle is not displaced and the plasma nozzle has a high cooling capacity.

In order to achieve the above object, the first invention provides:
The torch body,
An electrode that is provided on the shaft core of the torch body and generates a main plasma arc with the workpiece;
A plasma nozzle for generating a pilot arc between the electrodes;
A heat dissipating member provided in the torch body and to which the nozzle is attached;
In a plasma welding torch comprising a shield gas cup surrounding the tip of the nozzle and screwed to the torch body,
The insertion portion of the nozzle to the heat radiating member and the inserted portion of the heat radiating member into which the insertion portion is inserted and in contact are formed in a conical shape,
A gas lens sandwiched between a step formed on the outer peripheral surface of the remaining portion of the nozzle and a step formed on the inner peripheral surface of the tip of the cup;
The nozzle is inserted into the heat radiating member, and the cup is screwed to the torch main body, whereby the nozzle is positioned with respect to the electrode by the cup and the gas lens. .

The second invention is
Instead of forming a stepped portion on the outer peripheral surface of the remaining portion of the nozzle according to the first invention, the outer peripheral surface and the inserted portion of the gas lens into which the outer peripheral surface is inserted and in contact are conical. A plasma welding torch characterized by being formed.

The third invention is
The plasma welding torch according to the first invention or the second invention, wherein fins are provided on a surface to be cooled of the heat radiating member.

  In the plasma welding torch of the present invention, the insertion side of the plasma nozzle to the heat radiating member is formed in a conical shape, and the inserted portion of the heat radiating member that is in contact with the plasma nozzle is also formed in a conical shape. The accuracy of machining the member into a conical shape is higher than that of the screwing structure. Therefore, since the conical surfaces are brought into contact with each other, the center axis of the electrode and the center axis of the plasma nozzle do not shift when the plasma nozzle is mounted on the torch body. Therefore, good plasma can be generated.

  Further, since the insertion surface of the plasma nozzle and the insertion surface of the heat radiating member are processed in a conical shape, the contact area is enlarged and the adhesion is good as compared with the case of screwing. Therefore, since the thermal resistance is small and the cooling capacity is large, the plasma nozzle is not easily burned out. Moreover, since the heat radiating member in contact with the plasma nozzle is in contact with the refrigerant, the plasma nozzle and the refrigerant are close to each other, and the cooling capability of the plasma nozzle is high. Moreover, since the plasma nozzle is indirectly cooled with water, there is no fear of water leakage.

  In addition, the gas lens with thermal conductivity is in direct contact with the plasma nozzle, the heat of the plasma nozzle is transferred to the gas lens, and the shield gas that passes through the gas lens absorbs this heat, thus promoting the cooling of the plasma nozzle. can do.

[Embodiment 1]
Embodiments of the present invention will be described based on examples with reference to the drawings.
FIG. 1 is a cross-sectional view of a plasma welding torch according to Embodiment 1 of the present invention. In the figure, an electrode 2 (usually formed of tungsten) is provided at the axial center portion of the torch body 1, and this electrode 2 is attached to the torch body 1 by an electrode support member 3. The electrode support member 3 is surrounded by an insulating member 4.

  The plasma nozzle 5 is cylindrical and conductive, and a plasma ejection hole 5a is formed at the tip. The electrode 2 is inserted into the centering stone 6 so that the tip protrudes into the plasma nozzle 5. A centering stone 6 is inserted into the plasma nozzle 5. This centering stone 6 has a function to prevent the axial displacement of the electrode 2, and has a cylindrical shape and is electrically insulating, and prevents the pilot arc from being ignited at a place other than between the electrode 2 and the plasma nozzle 5. Yes. In addition, the centering stone 6 may have a plasma gas hole 6a through which the plasma gas 7 is ejected in the axial direction.

The heat radiating member 8 is formed of a material having high thermal conductivity such as copper or copper alloy, and is attached to the torch body 1. The plasma nozzle 5 is inserted into the heat radiating member 8, but the insertion side of the plasma nozzle 5 into the heat radiating member 8 is formed in a conical shape. The inserted portion of the heat radiating member 8 that is in contact with the plasma nozzle 5 is also formed in a conical shape.
A refrigerant flow path 9 for cooling the heat radiating member 8 is provided around the heat radiating member 8, and the refrigerant flows therethrough. The refrigerant flows through the refrigerant case 10 and does not leak from the torch body 1. The partition member 11 has a function of partitioning the refrigerant flow side 9a and the return side 9b.

The shield gas cup 12 has heat resistance, surrounds the tip of the plasma nozzle 5, is screwed to the torch body 1, and the shield gas 13 is ejected. A step portion 5 b is formed on the outer peripheral surface of the plasma nozzle 5 on the plasma ejection hole 5 a side, and a step portion 12 a is formed on the inner peripheral surface of the tip portion of the shield gas cup 12.
The gas lens 14 rectifies and ejects the shield gas 13. Further, the gas lens 14 has thermal conductivity, and the heat of the plasma nozzle 5 is transmitted to the gas lens 14, and the shield gas 13 that passes through the gas lens 14 cools the gas lens 14 and lowers the temperature of the plasma nozzle 5. .
The plasma nozzle 5 is inserted into the heat radiating member 8, the step portion 5b of the plasma nozzle 5 is caught on the upper surface 14a of the gas lens, and the lower surface 14b is caught on the step portion 12a of the shield gas cup. The gas lens 14 is configured to press the plasma nozzle 5 against the heat radiating member 8 from below.

Next, the operation will be described.
An electrode 2 is attached to the torch body 1 by an electrode support member 3. The electrode support member 3 is surrounded by an insulating member 4. The electrode 2 is inserted into the centering stone 6 so that the tip protrudes into the plasma nozzle 5. A centering stone 6 is inserted into the plasma nozzle 5. A heat radiating member 8 is attached to the torch body 1, and a plasma nozzle 5 is inserted into the heat radiating member 8. A refrigerant flow path 9 is provided around the heat dissipating member 8, and the refrigerant flows. The refrigerant flows in the refrigerant case 10.

A shield gas cup 12 surrounds the tip of the plasma nozzle 5, is screwed to the torch body 1, and a shield gas 13 is ejected. The gas lens 14 rectifies and ejects the shield gas 13. Further, the heat of the plasma nozzle 5 is transmitted to the gas lens 14, and the shield gas 13 that passes through the gas lens 14 cools the gas lens 14 and lowers the temperature of the plasma nozzle 5.
The plasma nozzle 5 is inserted into the heat radiating member 8, the gas lens 14 is sandwiched between the step portion 5 a of the plasma nozzle and the step portion 12 a of the shield gas cup, and the shield gas cup 12 is screwed to the torch body 1. Thus, positioning of the plasma nozzle 5 with respect to the electrode 2 is performed.

  A pilot arc is generated between the electrode 2 and the plasma nozzle 5, and a main plasma arc is generated using the plasma gas 7 between the electrode 2 and an object to be welded (not shown). The heat of the plasma nozzle 5 is transmitted to the heat radiating member 8 and is cooled by the refrigerant. Further, heat is transmitted from the plasma nozzle 5 to the gas lens 14, and the shield gas 13 absorbs this heat.

As a result, the plasma welding torch of the present invention has the following effects.
The insertion side of the plasma nozzle to the heat radiating member is formed in a conical shape, and the inserted portion of the heat radiating member that is in contact with the plasma nozzle is also formed in a conical shape. The accuracy of machining the member into a conical shape is higher than that of the screwing structure. Accordingly, since the conical surfaces are brought into contact with each other, the center axis of the electrode and the center axis of the plasma nozzle do not shift when the plasma nozzle is mounted on the torch body. Therefore, good plasma can be generated.

  Further, since the insertion surface of the plasma nozzle and the insertion surface of the heat radiating member are processed in a conical shape, the contact area is enlarged and the adhesion is good as compared with the case of screwing. Therefore, since the thermal resistance is small and the cooling capacity is large, the plasma nozzle is not easily burned out. Moreover, since the heat radiating member in contact with the plasma nozzle is in contact with the refrigerant, the plasma nozzle and the refrigerant are close to each other, and the cooling capability of the plasma nozzle is high. Moreover, since the plasma nozzle is indirectly cooled with water, there is no fear of water leakage.

  In addition, the gas lens with thermal conductivity is in direct contact with the plasma nozzle, the heat of the plasma nozzle is transferred to the gas lens, and the shield gas that passes through the gas lens absorbs this heat, thus promoting the cooling of the plasma nozzle. can do.

[Embodiment 2]
FIG. 2 is a cross-sectional view of the plasma welding torch according to the second embodiment of the present invention. In the figure, the refrigerant channel 9 side of the heat radiating member 8 is also formed in a conical shape. For the other functions, the same functions as those of the plasma welding torch according to the first embodiment shown in FIG.
As a result, since the thickness of the heat radiating member 8 can be reduced, the thermal resistance is reduced, the heat of the plasma nozzle 5 can be efficiently transmitted to the refrigerant, and the cooling of the plasma nozzle 5 can be promoted. .

[Embodiment 3]
FIG. 3 is a cross-sectional view of the plasma welding torch according to the third embodiment of the present invention. In the drawing, a groove is dug so that the refrigerant flows in a spiral shape on the refrigerant flow path 9 side of the heat radiating member 8. For the other functions, the same functions as those of the plasma welding torch according to the first embodiment shown in FIG.
As a result, the contact area between the heat radiating member 8 and the refrigerant increases, and the refrigerant contacts the heat radiating member 8 evenly. Therefore, the heat of the plasma nozzle 5 can be efficiently transmitted to the refrigerant, and the cooling of the plasma nozzle 5 is promoted. can do.

[Embodiment 4]
FIG. 4 is a cross-sectional view of the plasma welding torch according to the fourth embodiment of the present invention. In the drawing, a plurality of stepped turning grooves are formed on the refrigerant flow path 9 side of the heat radiating member 8. Further, instead of forming the step portion 5b on the surface where the plasma nozzle 5 of the plasma welding torch of the first embodiment shown in FIG. 1 contacts the gas lens 14, this outer peripheral surface is formed in a conical shape. . Further, the inserted portion of the gas lens 14 in which the outer peripheral surface is inserted and brought into internal contact is also formed in a conical shape. For the other functions, the same functions as those of the plasma welding torch according to the first embodiment shown in FIG.
As a result, since the surface area is enlarged by the stepped turning grooves of the heat radiating member 8, the heat of the plasma nozzle 5 can be efficiently transmitted to the refrigerant, and the cooling of the plasma nozzle 5 can be promoted.
Further, the contact area between the front end side of the plasma nozzle 5 and the gas lens 14 is increased, and further, by tightening the shield gas cup 12 to the torch body 1, the adhesion of the contact surface is increased. can get. Accordingly, since the efficiency of conduction of heat released from the plasma nozzle 5 through the gas lens 14 to the shield gas flow is increased, the plasma nozzle 5 can be efficiently cooled.

  FIG. 5 is a diagram for explaining a method of performing the measurement test of the plasma nozzle life of the plasma welding torch according to the first embodiment described above, and FIG. 6 illustrates the life of the plasma nozzle of the plasma welding torch according to the first embodiment. It is the figure which compared these measurement results with the plasma welding torch of prior art 1 and prior art 2.

  In FIG. 5, the main plasma arc 19 is continuously ignited under the conditions that the inner diameter of the plasma nozzle 5 is 2.6 mm, the plasma current is 60 A, and the distance L1 between the tip of the plasma nozzle 5 and the water-cooled copper plate 18 is 3 mm. The time until 5 was consumed was measured.

As a result, the fastest plasma nozzle was consumed in the plasma welding torch of the prior art 1 in which the plasma nozzle was screwed to the torch body and indirectly cooled with water.
The next fastest wear was the plasma welding torch of Prior Art 2 where the plasma nozzle was directly water cooled. This is because the O-ring is cut or water leaks due to thermal deformation of the plasma nozzle.
And it was the plasma welding torch of the first embodiment that was able to ignite the main plasma arc without any trouble for the longest time, and the life was extended more than twice as compared with the plasma welding torch of the prior art 2. It was possible to improve significantly.

It is sectional drawing of the plasma welding torch of Embodiment 1 of this invention. It is sectional drawing of the plasma welding torch of Embodiment 2 of this invention. It is sectional drawing of the plasma welding torch of Embodiment 3 of this invention. It is sectional drawing of the plasma welding torch of Embodiment 4 of this invention. It is a figure explaining the method of implementing the measurement test of the lifetime of the plasma nozzle of the plasma welding torch of Embodiment 1. FIG. It is the figure which compared the measurement result of the lifetime of the plasma nozzle of the plasma welding torch of Embodiment 1 with the plasma welding torch of the prior art 1 and the prior art 2. FIG. It is a figure which shows the plasma welding torch of the prior art 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torch main body 2 Electrode 3 Electrode support member 4 Insulating member 5 Plasma nozzle 5a Plasma ejection hole 5b Plasma nozzle step 6 Centering stone 6a Plasma gas hole 7 Plasma gas 8 Heat radiation member 9 Refrigerant channel 9a Refrigerant channel flow side 9b Refrigerant channel return side 10 Refrigerant case 11 Partition member 12 Shield gas cup 12a Shield gas cup step 13 Shield gas 14 Gas lens 14a Gas lens Upper surface 14b Lower surface 15 of gas lens Torch body 16 (of prior art 1) Plasma nozzle 17a (of prior art 1) Plasma gas flow path 17 Insulation guide 18 Water-cooled copper plate 19 Main plasma arc L1 The tip of plasma nozzle 5 and water-cooled copper plate 18 Distance of

Claims (3)

The torch body,
An electrode that is provided on the shaft core of the torch body and generates a main plasma arc with the workpiece;
A plasma nozzle for generating a pilot arc between the electrodes;
A heat dissipating member provided in the torch body and to which the nozzle is attached;
In a plasma welding torch comprising a shield gas cup surrounding the tip of the nozzle and screwed to the torch body,
The insertion portion of the nozzle to the heat radiating member and the inserted portion of the heat radiating member into which the insertion portion is inserted and in contact are formed in a conical shape,
A gas lens sandwiched between a step formed on the outer peripheral surface of the remaining portion of the nozzle and a step formed on the inner peripheral surface of the tip of the cup;
The nozzle is inserted into the heat radiating member, and the cup is screwed to the torch main body, whereby the nozzle is positioned with respect to the electrode by the cup and the gas lens. .   In place of forming a step portion on the outer peripheral surface of the remaining portion of the nozzle according to claim 1, the outer peripheral surface and the inserted portion of the gas lens into which the outer peripheral surface is inserted and in contact are formed in a conical shape. A plasma welding torch characterized by that. The plasma welding torch according to claim 1 or 2, wherein fins are provided on a surface to be cooled of the heat radiating member.

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