JPS61260600A - Plasma torch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transfer type plasma jet generating plasma torch used mainly for metal welding, cutting, melting, thermal spraying, surface processing, etc. be.

[Prior Art] A conventional plasma torch of this type was constructed as shown in FIG. 5, which is a sectional view of the main part of the nozzle portion, with cooling means and sealing means omitted.

In the figure, a plasma torch 1 includes a main body part 2 that holds the entire apparatus by a known grip or attachment means, supports an electrode rod 3 at its center, and has a known cooling means (not shown in the figure) inside. A nozzle part 4 that carries out discharge between the electrode rod 3 and guides the ejected shielding gas, and a nozzle part 4 that arranges the electrode rod 3 at the center of the plasma torch 1 and fixes it. It is composed of an electrode holder part 5.

The main body part 2 is made of an insulating material, and includes a main body base 21 into which a holder base 51 constituting the electrode holder part 5 is inserted.

The electrode rod 3 is a JIS standardized product and is a well-known product.

The nozzle part 4 includes a plasma injection port 45 at the tip of the central part,
The nozzle base 41 has a plasma gas supply port 42 that supplies plasma gas made of an inert gas such as argon gas, and an electrode made of ceramic or the like inside the nozzle base 41. It has a heat shield ring 43 for centering the rod 3 and preventing backflow of heat on the plasma injection port 45 side. A plurality of small holes 46 are bored in the heat shield ring 43 to allow plasma gas to flow therethrough. Note that an insulating sleeve 44 is inserted into the electrode rod 3 located at the center of the nozzle part 4 between the end of the holder base 51 and the heat shield ring 43 of the electrode holder part 5, and the nozzle base 41 This prevents electrical discharge from occurring between the inner wall of the electrode rod 3 and the electrode rod 3.

The electrode holder part 5 is inserted into the holder base 51 inserted into the main body 2 and the center of the holder base 51, and the collet chuck 52 has its tapered part brought into contact with the narrowed diameter part 54 of the holder base 51. The other end is fitted into a collet pressing screw 53. The collet pressing screw 53 is screwed into the holder base 51, and by being screwed into the holder base 51, the collet chuck 52 clamps the electrode rod 3 and prevents electrical connection between the electrode rod 3 and the holder base 51. - Make mechanical connections.

The plasma torch 1 configured as described above transmits a high frequency between the holder base 51 of the electrode holder part 5 electrically and mechanically connected to the electrode rod 3 and the nozzle base 41 constituting the nozzle part 4. By applying this voltage, plasma gas such as argon gas is ionized into a plasma state, and a voltage is also applied between the electrode rod 3 and the nozzle base 41 to generate a pilot arc, and the pilot arc jets. When argon gas or the like is ionized into a plasma state and transferred between the materials to be welded, etc., the electrode rod 3 and the materials to be welded, etc. become substantially electrically conductive. When this state is reached, if a high voltage is applied between the electrode rod 3 and the material to be welded, and a large current is passed, a plasma main arc of 8 temperature will be generated, and the high temperature plasma main arc will weld or Depending on the application, it can be used for cutting, welding, melting, surface processing, high temperature processing, etc.

[Problems to be solved by the invention] As mentioned above, this type of plasma torch is used for applications such as metal welding and cutting, which are intended to be used in relatively short cycles, and the electrode lifespan is limited. It has a structure that emphasizes maintainability. That is, compared to plasma torches in which the electrodes are directly water-cooled, it has the advantage of being simpler and easier to maintain.

Therefore, regarding the short electrode life, in the conventional plasma torch, an inert plasma gas such as argon gas supplied from the plasma gas supply port 42 is supplied to the insulating sleeve 44 fitted to the electrode rod 3. and nozzle base 41
Since the hollow portion between the insulation sleeve 44 and the inner wall of the insulation sleeve 44 is used as a passage, and the plasma gas flows outside the insulating sleeve 44, the electrode rod 3 is not directly cooled, which causes the electrode temperature to rise. When the temperature of the electrode rod 3 increases, the range in which thermoelectrons can jump out becomes wider, and series arcs, side arcs, etc. are more likely to occur.

Therefore, an increase in the temperature of the ffi pole causes a factor that not only shortens the electrode life chemically, but also shortens the electrode life electrically.

Further, the inert plasma gas passage extends from the plasma gas supply port 42 of the nozzle section 4 to the plasma injection port 45, and between the insulating sleeve 44 and the electrode rod 3.
If they are in close contact with each other, the electrode rod 3 will be placed in an inert gas atmosphere. However, when inserting the electrode rod 3, the space formed by the holder base 51, the collet chuck 52, and the collet pressing screw 53, which constitute the electrode holder part 5, is filled with air.
When the space is screwed onto the holder base 51 and sealed, the atmosphere remains in the space. Therefore, the residual atmosphere is isolated from the plasma gas flow path, and even when the plasma torch 1 is in use, the residual atmosphere remains within the electrode holder portion 5. And electrode rod 3
When the temperature of the electrode rod 3 increases, the surface of the electrode rod 3 will be oxidized due to the residual atmosphere.

Furthermore, if the collet pressing screw 53 is used without being sealed in the holder base 51, the plasma gas flow flowing through the nozzle part 4 will reduce the pressure inside the holder base 51 according to Bernoulli's theorem, so that the atmosphere will be absorbed into the holder base 51. 5
1 and the collet pressing screw 53, and as in the former case, the surface of the electrode rod 3 is oxidized. Electrode rod 3
Even at the location where the electrode rod 3 is clamped by the collet chuck 52, the electrode rod 3 repeatedly contracts and expands due to temperature changes, and oxidation of the surface of the electrode rod 3 progresses. And electrode rod 3
Oxidation on the surface of the torch will result in poor contact with the current-carrying parts, making it impossible to use it as a plasma torch.

Therefore, the present invention aims to maintain the characteristics of being simple and easy to maintain, and to extend the life of the electrodes of an air-cooled plasma torch.

[Means for Solving the Problems] The plasma torch according to the present invention includes a collet chuck that clamps the electrode rod, an insulating sleeve inserted through it, a flow path for an inert plasma gas between the heat shield ring, and the electrode rod. It was formed.

[Function] According to the present invention, an inert plasma gas is flowed along the surface of the electrode rod, and when the plasma torch is used, the electrode rod is always cooled by the plasma gas flow flowing along the electrode rod.1.・、
This suppresses the rise in temperature of the electrode rod. Therefore, without changing the basic structure of the conventional plasma torch, the temperature rise of the electrode rod can be suppressed and continuous use is possible.

[Example] Next, the present invention will be explained in detail.

FIG. 1 is a cross-sectional view of essential parts showing an example of a plasma torch according to an embodiment of the present invention, and the cooling means of the nozzle part and the sealing means such as an O-ring are omitted, but it goes without saying that they can be replaced by known means. can be used.

FIG. 2 is a cross-sectional view taken along the line A-A in FIG.
3 is a sectional view taken along line B-8 in FIG. 1, and FIG. 4 is a sectional view taken along line C--C in FIG. 1. In the drawings, the same reference numerals and symbols as those in FIG. 5 indicate the same or corresponding components of the conventional apparatus.

In particular, to explain the difference from conventional plasma torches, a heat shield ring 43 that also serves as centering of the electrode rod 3 is inserted between the inner wall of the nozzle base 41 of the nozzle part 4 and the electrode rod 3.
As shown in the cross-sectional view taken along cutting line A-A, a notch groove 468 is carved on the inner diameter side that contacts the electrode rod 3. The cutout groove 46a forms a plasma gas passage and has a cross-sectional area that is sufficient to maintain the ignition of the plasma arc. Further, the insulating sleeve 44a is inserted in contact with the inner wall of the nozzle base 41, and forms a plasma gas passage between it and the electrode rod 3.

These heat shielding rings 43a and insulation sleeves 4
The function of 4a is the same as that of conventional devices, and the heat shield ring 43a is for heat backflow and centering of the electrode rod 3, and the insulating sleeve 44a prevents discharge between the electrode rod 3 and the nozzle base 41. It is something.

As shown in the cross-sectional view taken along the line 1i1B-B, the main body 2 has a collet chuck 52a inserted therein which holds the inserted holder bag 51alC harvesting rod 3, and the collet chuck 52a is used as a collet chuck. A plasma gas passage 52d, which also serves as a notch groove for the purpose, is carved. The gas passage 52d has a cross-sectional area that is sufficient to form a flow path for igniting a plasma arc.

The holder base 51a through which the electrode rod 3 is inserted is provided with a hole 51c having a diameter sufficient for the outer diameter of the electrode rod 3 to pass therethrough and for the plasma gas flow to flow therethrough. A plasma gas supply port 51b is provided in the holder base 51a and communicates with a fitting hole into which the collet chuck 52a is inserted.

Since the collet chuck 52a is in contact with the collet pressing screw 53, in order to prevent the plasma gas from being supplied from the supply port 51b and being cut off by the collet chuck 52, a groove is provided on the collet pressing screw 53 side of the collet chuck 52. As shown in the cut plane taken along the cutting line CC in FIG. 1 in FIG. 4, a notch groove 52b is formed.

In the plasma torch of this embodiment configured as described above, when an inert plasma gas such as argon gas is supplied from the plasma gas supply port 51b, the plasma gas is transferred to the collet chuck 52a and the collet pressing screw 53. Notch groove 52b carved in the collet chuck through the
and is guided to the hollow portion 52c of the collet chuck 52a.

Since the metal rod 3 to be clamped exists in the hollow portion 52c of the collet chuck 52a, the plasma gas flow flows along the surface of the metal rod 3, and the plasma gas passage 52d1 which also serves as a notch groove for use as a collet chuck to clamp the metal rod 3 exists. Pass through the common hole 51c of the electrode rod 3 of the holder base 51a,
Furthermore, it reaches the plasma injection port 45 of the nozzle base 41 between the inside of the insulating sleeve 44a and the surface of the electrode rod 3 and through the notch 46a of the heat shield ring 43a.

Therefore, when the electrode rod 3 is in the state of using plasma gas, the entire length of the electrode rod 3 is cooled by the plasma gas. The cavity formed inside the plasma torch 1 serves as a flow path for plasma gas, which is an inert gas, and even if the collet pressing screw 53 is removed when inserting the metal rod 3, the atmosphere remaining inside the plasma leaked by. Therefore, the electrode rod 3 is always placed in an atmosphere of plasma gas, which is an inert gas, and the electrode rod 3 is always surrounded by an atmosphere of plasma gas, which is an inert gas.
oxidation can be prevented.

As mentioned above, in this example, the plasma gas flow path is provided along the entire length of the electrode rod, and there is no space in the plasma torch where the atmosphere remains. In addition to cooling with plasma gas, the electrode rod can always be placed in an atmosphere of plasma gas, which is an inert gas, so that the temperature rise of the electrode rod can be suppressed and the plasma torch can be used continuously. In addition, since the electrode rod does not oxidize, the life of the electrode can be extended.

In the above embodiment, plasma gas is supplied from the plasma gas supply port at the base of the holder and flows out from the end of the collet chuck toward the injection port of the nozzle. A hole can be drilled near the end to serve as a plasma gas flow path.

However, when carrying out the present invention, a more effective plasma torch can be obtained by eliminating a cavity portion in which gas stagnates other than the plasma gas flow path.

[Effects of the Invention] As described above, the present invention forms a plasma gas passage over the entire length of the electrode rod disposed at the center of the main body of a transfer type plasma torch. is an inert plasma gas flow path, and the electrode rod is cooled with plasma gas, and the electrode rod can always be placed in an atmosphere of plasma gas, which is an inert gas, so the temperature of the electrode rod can be reduced. You can hold down the rise and use the plasma torch continuously.

Furthermore, since the electrode rod is not oxidized, the life of the electrode can be extended.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main parts of a plasma torch according to an embodiment of the present invention, with cooling means and sealing means for the nozzle section omitted, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 1 is a sectional view taken along the line B-8 in FIG. 1, FIG. 4 is a sectional view taken along the line C-C in FIG. 1, and FIG. 5 is a sectional view taken along the line C-C in FIG. FIG. 2 is a sectional view of main parts of a plasma torch. In the figure, 1... plasma torch, 2... main body, 3...
Electrode rod, 4... nozzle part, 5... part of electrode holder. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] A transfer type plasma torch having an electrode rod disposed in the center of the plasma torch body, characterized in that a plasma gas passage is formed along the entire length of the electrode rod and flows along the surface of the electrode rod. Plasma torch.