JPH09239545A - Plasma torch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mix gases within a torch, to unnecessitate a gas mixer and also to separately feed gases by forming a hole communicating a secondary gas feeding path with a tertiary gas feeding path in a plasma torch. SOLUTION: A nozzle 2 is provided with a three-layer structure consisting of a first nozzle 6, a second nozzle 7 and a third nozzle 8. Plural holes 7b are arranged on a concentric circle making an orifice 7a center in the conical surface of the second nozzle 7. This hole 7b is provided with an inclination of about 45 degrees to the tertiary gas path 20 in the flat surface including the axial center of the torch 1, and also formed with a prescribed angle in the radical direction in the flat surface rectangular to the axial center of the torch 1. The plasma torch 1 constructed like this is allowed to mix two kinds of gases separately fed at the chip end of the torch and eject mixed gases without previously mixing two kinds of gases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma torch, and more particularly to a plasma torch that supplies three layers of air flow to perform cutting.

[0002]

2. Description of the Related Art A plasma cutting apparatus generates a plasma arc by applying a high voltage to a plasma gas from an electrode mounted inside a nozzle at the tip of a plasma torch, and ejects the plasma arc from the tip of the nozzle to generate a high temperature and its ejection. The cutting is done by physical energy. As the plasma gas, argon gas or hydrogen gas is used when cutting non-ferrous metal or non-metal, and oxidizing gas such as oxygen gas or air is supplied when cutting steel plate or stainless steel plate.

However, since the reaching force is weak only with the plasma jet, the secondary air stream is ejected in a form along the circumference of the plasma jet. Here, in cutting metal, since oxygen can be cut with high efficiency by supplying and burning oxygen, oxygen is often used in the secondary air flow when the plasma gas is not oxygen. In that case, it is effective to eject a tertiary airflow around the secondary airflow in order to improve the oxygen concentration at the cutting site.

At this time, inexpensive air is used for the secondary air flow or the tertiary air flow, but from the viewpoint of maintaining the purity of the plasma gas or oxygen flowing therein, it is possible to mix and eject these gases. Has been done. Depending on the cutting material, a mixed gas flow may be used as the plasma gas.

[0005]

When the mixed airflow is used as described above, it is supplied to the torch after being mixed in a predetermined ratio by a gas mixer or the like in advance. Therefore, a gas mixer for mixing two or more gases is required, making the plasma cutting system expensive. Further, in order to supply the mixed gas to the nozzle, the material of the supply hose must be resistant to all the mixed gases.

Further, when the gas to be mixed is a combination of a flammable gas and a combustion-supporting gas such as a hydrocarbon-based gas and oxygen, supplying them in a mixed state may sometimes cause a flashback or an explosion. There was a problem, and it required careful handling.

[0007]

In order to solve the above problems, a plasma torch according to the present invention is a plasma for cutting by supplying a plasma gas, a secondary gas and a tertiary gas to a nozzle arranged at the tip of the plasma torch. A torch,
An electrode arranged in the center of the plasma torch, a first nozzle member that forms a plasma gas passage between the electrode, and a second nozzle that forms a secondary gas passage between the first nozzle member. A third nozzle member that forms a tertiary gas passage between the member and the second nozzle member; a first cap member fitted to the second nozzle member; It is composed of a second cap member that forms a secondary gas supply passage and a third cap member that forms a tertiary gas supply passage between the second cap member, and connects the secondary gas supply passage and the tertiary gas passage. It is characterized in that holes are provided.

Further, the hole is provided in the second nozzle member, and the hole connects the secondary gas supply passage and the tertiary gas passage through the secondary gas passage. To do.

Further, the hole is provided in the second cap, and the hole connects the secondary gas supply passage and the tertiary gas passage via the tertiary gas supply passage. .

In the tertiary gas supply passage or the tertiary gas passage, an injector structure is formed by forming a path sectional area on the upstream side of the gas supply passage with respect to the hole narrower than the vicinity of the opening of the hole. Is desirable.

Further, by forming the hole at a predetermined angle from the radial direction in a plane orthogonal to the axis of the plasma torch, the gas passing through the hole can be swirled. You can

With the above-mentioned structure, the plasma torch according to the present invention can mix the gas inside the torch, the gas mixer is not required, and the gas can be individually supplied. Become.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a plasma torch according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of the tip portion of the plasma torch according to the first embodiment, and FIG. 2 is an enlarged sectional view of the nozzle.

FIG. 1 is a sectional view of the tip portion of the plasma torch 1. As an outline of the configuration at the tip of the torch 1, an electrode 4 is arranged so as to match the axis of the torch 1, and a nozzle 2 is fitted to the tip of the electrode 4 via a centering stone 5. The cap 3 is fitted to the nozzle 2 and attached to the torch 1. The cap 3 has a function of protecting the tip of the torch 1 and locking the nozzle 2 to the torch 1. Each of these will be described below.

The electrode 4 arranged at the center of the torch 1 is a cylindrical member having a closed tip, and an electrode material 4a made of tungsten, hafnium or the like is embedded in the tip. When oxygen is used as the plasma gas, hafnium, which has a high oxide melting temperature, is used because tungsten burns out instantly. A cooling pipe 4b is arranged inside the electrode to supply cooling water to the tip of the electrode. The electrode 4 is supported behind the torch 1,
A plasma gas supply path 12 is formed around the electrode 4 with a gap.

A centering stone 5, which is a ceramic cylindrical member, is fitted around the outer periphery of the electrode 4. The centering stone 5 is provided with a plurality of plasma gas passage holes 5a having a predetermined angle with respect to the radial direction of the cross section of the torch 1, and the plasma gas supplied from the plasma gas supply passage 12 passes through the passage holes 5a. As a result, the gas is supplied to the plasma gas passage 18 described later while swirling. As the plasma gas swirls, the starting point of the plasma arc is stabilized, preventing the series arc and stabilizing the generation of the plasma arc. The centering stone 5 is formed of an insulating material and has a function of insulating the electrode and the nozzle 2 from each other.

As shown in FIG. 2, the nozzle 2 has a three-layer structure composed of a first nozzle 6, a second nozzle 7 and a third nozzle 8. Each nozzle member is a hollow member having a substantially cylindrical body portion and a conical tip portion projecting forward, and an orifice for ejecting a plasma jet or the like is formed at the tip of the cone.

First, the first nozzle 6 is fitted to the outer periphery and front of the centering stone 5, and a plasma gas passage 18 is formed with a gap between the conical rear surface of the first nozzle 6 and the tip of the electrode 4. ing. The plasma gas supplied from the plasma gas supply path 12 is swirled by the plasma gas passage hole 5a of the centering stone 5 while being swirled.
Erupted within 18.

The plasma torch according to the present embodiment is of a transfer type. First, a voltage is applied to the electrode 4 and at the same time, a reverse voltage is applied to the nozzle to discharge between the electrode and the inner surface of the first nozzle 6 to generate plasma. The plasma gas supplied into the gas passage 18 is ionized to form a pilot arc. Then, a reverse voltage is applied to the work, the reverse voltage applied to the nozzle is cut off, and the arc is transferred between the electrode and the work by conducting the plasma gas so that a plasma arc is generated. The plasma arc is narrowed and cooled in the orifice 6a provided at the tip of the first nozzle 6, and a higher temperature plasma jet is generated.

A second nozzle 7 is fitted on the outer periphery of and in front of the first nozzle 6, and there is a secondary gap with a gap between the conical front surface of the first nozzle 6 and the conical rear surface of the second nozzle 7. Gas passage
19 are formed. An orifice 7a is provided at the tip of the cone which is the front surface of the second nozzle 7, and the orifice 7a is formed with a smaller diameter than the orifice 6a provided in the first nozzle 6. Therefore, the plasma gas ejected from the orifice 6a is restricted by the orifice 7a,
Further, it becomes a high temperature and high speed plasma jet.

An orifice 7 is provided on the conical surface of the second nozzle.
A plurality of holes 7b are arranged on a concentric circle centered on a. The hole 7b is provided so as to be inclined by about 45 degrees with respect to the path of the tertiary gas passage 20 in a plane including the axis of the torch 1, and in the plane orthogonal to the axis of the torch 1. It is formed at a predetermined angle from the radial direction.

In the figure, the diameter of the hole 7b is stepped because the diameter of the hole 7b is 0.2 to 0.3 mm and it is difficult to process the hole. . In addition, the raised portion 7 is provided upstream of the hole 7b on the front surface of the second nozzle 7.
c is provided, and is configured so as to reduce the path cross-sectional area of the tertiary gas passage 20 described later.

A step portion 7e is provided on an end edge of the outer peripheral surface of the second nozzle 7 on the torch 1 side, and the first cap 9 is attached to the torch 1 while being locked to the step portion 7e. . That is, the first nozzle 6 and the second nozzle 7 are locked to the torch 1 by the first cap 9. A cooling water passage 15 is formed between the first cap 9 and the outer peripheral surface of the body of the first nozzle 6, and cooling water is supplied from a cooling water supply passage (not shown) to cool the nozzle 2. .

A secondary gas passage hole 7d, which is a plurality of holes, is formed in the body portion of the second nozzle 7, and a second cap 10 is fitted on the outer periphery of the body portion of the second nozzle 7 and in front thereof. Has been done. That is, the second cap 10 forms a secondary gas supply passage 16 with a gap between the second cap 10 and the first cap 9, and the secondary gas supply passage 16 in the cap 3 forms a nozzle through the secondary gas passage hole 7d. The secondary gas passage 20 in 2 is configured to be able to supply the secondary gas. Secondary gas passage hole 7d is torch 1
Is formed at a predetermined angle from the radial direction of the cross section of the secondary gas, so that the secondary gas that has passed through the secondary gas passage hole 7d is supplied to the secondary gas passage 19 while swirling.

A third nozzle 8 is fitted on the front surface of the second nozzle 7 and forms a tertiary gas passage 20 with a gap between the third nozzle 8 and the second nozzle 7. The third nozzle 8 is also the first nozzle 6
And the orifice 8a at the tip of the second nozzle 7 as well as the second nozzle 7.
And the orifice 8a has other orifices 6a, 7a.
It is formed to have a larger diameter than the above, and is configured to eject the plasma gas, the secondary gas, and the tertiary gas.

A tertiary gas passage hole 8 is formed in the body of the third nozzle 8.
b is provided, and a step portion 8c is formed at the end edge of the outer peripheral surface of the body portion on the tip end side of the torch 1. The third nozzle 8 is locked to the torch 1 by fitting the third cap 11 to this step and attaching the third cap 11 to the torch body 1. The third cap 11 forms a tertiary gas supply passage 17 with a gap between the third cap 11 and the second cap 10. The tertiary gas is supplied from the tertiary gas supply pipe 14 in the main body of the torch 1 to the tertiary gas in the cap 2. Supply path 17, the tertiary gas passage hole 8
It is supplied to the tertiary gas passage 19 in the nozzle via b and is ejected together with the plasma jet.

Here, as described above, since the raised portion 7c is provided behind the hole 7b on the front surface of the second nozzle 7,
The tertiary gas passage 20 forms an injector structure.
That is, the tertiary gas passage 20 has a structure in which the path cross-sectional area fitted in the opening portion of the hole 7b rapidly expands,
The static pressure of the passing tertiary gas is reduced, and the secondary gas is sucked from the hole 7b. Therefore, the tertiary gas entrains and mixes the secondary gas and is ejected from the third orifice 8a together with the plasma jet.

Further, since the hole 7a is formed in a plane orthogonal to the axis of the torch 1 with a predetermined angle from its radial direction, the secondary airflow ejected from the hole 7a swirls. While mixing in the tertiary gas passage 20. Therefore, the secondary gas and the tertiary gas are smoothly and quickly mixed, and ejected from the orifice 8a of the third nozzle 8 as a uniform mixed gas.

With the above-mentioned configuration, in the plasma torch 1 according to the present invention, two kinds of gas supplied individually are mixed at the tip of the torch without mixing the two kinds of gas in advance. The mixed gas can be jetted out. In addition, the injector structure makes it possible to efficiently mix the secondary gas with the tertiary gas without requiring a high pressure for the secondary gas.

Next, a second embodiment according to the present invention will be described with reference to FIG. The same parts as those of the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted. The plasma torch in FIG. 3 has a different structure only in the second nozzle 21 as compared with the first embodiment.

The second nozzle 21 is fitted to the outer periphery and front of the first nozzle 6 as in the first embodiment, and a gap is formed between the conical front surface of the first nozzle 6 and the conical rear surface of the second nozzle 21. It has a secondary gas passage 19 therein. A step portion 21d is formed on the conical front surface of the second nozzle 21, and the third nozzle 8 is fitted to the inner peripheral surface of the step portion 21d.

The step portion 21d is provided with a hole 21b for communicating the secondary gas passage 19 in the nozzle 2 with the tertiary gas supply passage 17 in the cap 3. Therefore, the secondary gas passage 19
A part of the secondary gas supplied to (3) is ejected to the tertiary gas supply passage 17 through the hole 21b and mixed with the tertiary gas. The mixed gas is supplied to the tertiary gas passage 20 through the tertiary gas passage hole 21b provided in the body of the third nozzle 8 and is ejected together with the plasma jet.

Next, a third embodiment according to the present invention will be described with reference to FIG. In the present embodiment, the second nozzle 23 is not provided with a hole, and the second cap 24 is provided with a hole 24a in the vicinity of the contact portion with the second nozzle 23. Further, a raised portion 24b is provided on the front surface of the second cap 24 and on the torch 1 side of the hole 24a, and the passage cross-sectional area of the tertiary gas supply passage 17 formed between the third cap 11 and the third cap 11 is fitted. It is configured to be.

That is, the tertiary gas supply passage 17 has an injector structure, and the supplied gas is once compressed at the raised portion 24b and expanded at the opening of the hole 24a.
As a result, the flow velocity of the tertiary gas is locally increased and the static pressure is reduced, so that the suction efficiency of the secondary gas can be increased and the tertiary gas can be mixed with the tertiary gas.

Although the injector structure is provided in the first and third embodiments in the above embodiment and is not provided in the second embodiment, the injector structure is provided in any case. It is possible to choose to provide or not provide. 1 and 4, the hole is illustrated as a two-stage hole having a varying diameter.
Alternatively, the hole may have no step as shown in FIG. Further, although the inclination angle of the hole is shown as about 45 degrees, it is preferably about 30 to 45 degrees from the viewpoint of suction efficiency.

In the above embodiment, the gas is swirled by forming the hole and the passage hole located between the gas supply passage and the passage at a predetermined angle from the radial direction of the cross section of the torch 1. It was constructed and shown. But,
The direction of turning and the presence or absence of turning are arbitrary and are not particularly limited.

[0037]

As described above, the plasma torch according to the present invention can mix the secondary gas and the tertiary gas inside the torch tip. Further, by providing the injector structure, the secondary gas can be sucked by the tertiary gas, and the mixing efficiency can be increased. Further, by setting the angle in the hole that allows the secondary gas to communicate with the tertiary gas, the mixing after mixing can be made uniform.

Therefore, the independently supplied gases can be mixed at the tip of the nozzle, and even when the gases to be mixed are flammable gas and combustion supporting gas such as hydrocarbon gas and oxygen, It is possible to improve the safety against the used gas.

Further, since it is not necessary to mix in advance, the equipment of the mixer can be omitted, and the system can be simplified and the cost can be reduced. Also, since only one type of gas can pass through a single supply hose, the supply hose can be specialized, and it becomes easy to select a hose that is durable to the gas used, and the unit price can be reduced. .

[Brief description of drawings]

FIG. 1 is a sectional view of a tip portion of a plasma torch according to a first embodiment.

FIG. 2 is an enlarged sectional view of a tip portion of a plasma torch.

FIG. 3 is a sectional view of a tip portion of a plasma torch according to a second embodiment.

FIG. 4 is a sectional view of a tip portion of a plasma torch according to a third embodiment.

[Explanation of symbols]

 1 ... Torch 2 ... Nozzle 3 ... Cap 4 ... Electrode 5 ... Centering Stone 6 ... First Nozzle 7 ... Second Nozzle 7b ... Hole 8 ... Third Nozzle 9 ... First Cap 10 ... Second Cap 11 ... Third Cap 12 … Plasma gas supply line 13… Secondary gas supply pipe 14… Tertiary gas supply pipe 15… Cooling water passage 16… Secondary gas supply passage 17… Tertiary gas supply passage 18… Plasma gas passage 19… Secondary gas passage 20… Tertiary Gas passage 20a ... Injector 21 ... Second nozzle 23 according to second embodiment 23 ... Second nozzle 24 according to third embodiment 24 ... Second cap according to third embodiment

Claims (5)

[Claims] 1. A plasma torch for cutting by supplying a plasma gas, a secondary gas and a tertiary gas to a nozzle arranged at the tip of the plasma torch, and an electrode arranged at the center of the plasma torch, A first nozzle member that forms a plasma gas passage between the electrode, a second nozzle member that forms a secondary gas passage between the first nozzle member, and a tertiary gas between the second nozzle member A third nozzle member forming a passage, a first cap member fitted to the second nozzle member, a second cap member forming a secondary gas supply passage between the first cap member, and A plasma torch comprising: a third cap member that forms a tertiary gas supply path between the second cap member and the second cap member; and a hole that connects the secondary gas supply path and the tertiary gas path. 2. The hole is provided in the second nozzle member, and the hole connects the secondary gas supply passage and the tertiary gas passage through the secondary gas passage. The plasma torch according to claim 1. 3. The hole is provided in the second cap, and the hole connects the secondary gas supply passage and the tertiary gas passage through the tertiary gas supply passage. The plasma torch according to claim 1. 4. The injector structure is formed in the tertiary gas supply passage or the tertiary gas passage by forming a path cross-sectional area on the upstream side of the gas supply passage with respect to the hole narrower than the vicinity of the opening of the hole. The plasma torch according to claim 1, claim 2 or claim 3, wherein: 5. The hole is formed at a predetermined angle from the radial direction in a plane orthogonal to the axis of the plasma torch, and allows the gas passing through the hole to be swirled. The plasma torch according to any one of claims 1 to 4, which is configured.