JP3657683B2 - Plasma torch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma torch, and more particularly to a plasma torch that cuts by supplying a three-layer airflow.
[0002]
[Prior art]
The plasma cutting device generates a plasma arc by applying a high voltage to the plasma gas from the electrode attached to the inside of the nozzle at the tip of the plasma torch. Is done. As the plasma gas, argon gas or hydrogen gas is used when cutting non-ferrous metals or non-metals, and oxidizing gas such as oxygen gas or air is supplied when cutting steel plates or stainless steel plates.
[0003]
However, since the reaching force is weak only with the plasma jet, the secondary air stream is ejected along the periphery of the plasma jet. Here, in the cutting of the metal, oxygen can be cut efficiently by supplying oxygen and burning it. Therefore, when the plasma gas is not oxygen, oxygen is often used for the secondary airflow. 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.
[0004]
In that case, inexpensive air is used for the secondary air flow or the tertiary air flow, but these gases are mixed and ejected from the viewpoint of maintaining the purity of the plasma gas or oxygen flowing in the air. Yes. Depending on the cutting material, a mixed gas stream may be used for the plasma gas.
[0005]
[Problems to be solved by the invention]
As described above, when the mixed airflow is used, the airflow 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. Also, in order to supply the gas mixture to the nozzle, the material of the supply hose must be resistant to all the gases being mixed.
[0006]
In addition, when the gas to be mixed is a combination of a flammable gas and a combustion-supporting gas such as hydrocarbon gas and oxygen, supplying it in a mixed state may sometimes cause backfire or explosion, Care was required for handling.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a plasma torch according to the present invention is a plasma torch for cutting by supplying a plasma gas, a secondary gas and a tertiary gas to a nozzle disposed at the tip of the plasma torch, An electrode disposed in the center, 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 third nozzle member forming a tertiary gas passage with the second nozzle member, a first cap member fitted to the second nozzle member, and a secondary gas supply path between the first cap member And a third cap member that forms a tertiary gas supply path between the second cap member, and a hole for communicating the secondary gas supply path and the tertiary gas path is provided. Special To.
[0008]
Further, the hole is provided in the second nozzle member, and the hole communicates the secondary gas supply path and the tertiary gas path via the secondary gas path.
[0009]
Further, the hole is provided in the second cap, and the hole communicates the secondary gas supply path and the tertiary gas path via the tertiary gas supply path.
[0010]
Further, in the tertiary gas supply path or the tertiary gas path, it is desirable to form an injector structure by forming a path cross-sectional area upstream of the gas supply path from the hole narrower than the vicinity of the opening of the hole. .
[0011]
In addition, the hole passing through the hole can be swirled by forming the hole at a predetermined angle from the radial direction in a plane orthogonal to the axis of the plasma torch.
[0012]
With the above-described configuration, the plasma torch according to the present invention can mix gases inside the torch, eliminating the need for a gas mixer and supplying the gases individually.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The first embodiment of the plasma torch according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of the plasma torch tip according to the first embodiment, and FIG. 2 is an enlarged cross-sectional view of the nozzle.
[0014]
FIG. 1 is a cross-sectional view of the tip of the plasma torch 1. As an outline of the configuration at the tip of the torch 1, the electrode 4 is arranged so as to coincide with the axial center of the torch 1, and the nozzle 2 is fitted to the tip of the electrode 4 via a centering stone 5. A cap 3 is fitted to the nozzle 2 and attached to the torch 1, and the cap 3 protects the tip of the torch 1 and has a function of locking the nozzle 2 to the torch 1. Each will be described below.
[0015]
The electrode 4 disposed in the central portion of the torch 1 is a cylindrical member whose tip is closed, and an electrode material 4a such as tungsten or hafnium is embedded in the tip. When oxygen is used for the plasma gas, tungsten burns out instantaneously, so hafnium having a high oxide melting temperature is used. A cooling pipe 4b is disposed inside the electrode, thereby supplying cooling water to the tip of the electrode. The electrode 4 is supported behind the torch 1, and a plasma gas supply path 12 is formed with a gap around the electrode 4.
[0016]
A centering stone 5, which is a ceramic cylindrical member, is fitted to 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 path 12 passes through the passage holes 5a. Thus, the gas is supplied to the plasma gas passage 18 described later while turning. The plasma gas swirling stabilizes the generation point of the plasma arc, prevents the series arc and stabilizes the generation of the plasma arc. The centering stone 5 is formed of an insulator and has a function of insulating the electrode from the nozzle 2.
[0017]
As shown in FIG. 2, the nozzle 2 has a three-layer structure including 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 protruding forward, and an orifice for ejecting a plasma jet or the like is formed at the tip of the cone.
[0018]
First, the first nozzle 6 is fitted to the outer periphery and the 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. The plasma gas supplied from the plasma gas supply passage 12 is jetted into the plasma gas passage 18 while swirling through the plasma gas passage hole 5 a of the centering stone 5.
[0019]
The plasma torch according to this embodiment is 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. The plasma gas supplied inside is ionized to form a pilot arc. Thereafter, a reverse voltage is applied to the workpiece, the reverse voltage applied to the nozzle is cut off, and the plasma is made to conduct by transferring an arc between the electrode and the workpiece, thereby generating a plasma arc. The plasma arc is throttled and cooled at an orifice 6a provided at the tip of the first nozzle 6, and a higher temperature plasma jet is generated.
[0020]
A second nozzle 7 is fitted on the outer periphery and the front of the first nozzle 6, and a secondary gas passage 19 is provided with a gap between the conical front surface of the first nozzle 6 and the conical rear surface of the second nozzle 7. Is forming. An orifice 7 a is provided at the tip of the cone, which is the front surface of the second nozzle 7, and the orifice 7 a is formed with a smaller diameter than the orifice 6 a provided in the first nozzle 6. Therefore, the plasma gas ejected from the orifice 6a is throttled by the orifice 7a, and becomes a higher temperature and higher speed plasma jet.
[0021]
A plurality of holes 7b are arranged on a concentric circle centered on the orifice 7a on the conical surface of the second nozzle. The hole 7b is provided at an angle of approximately 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 a plane perpendicular to the axis of the torch 1. It is formed with a predetermined angle from the radial direction.
[0022]
In the drawing, the diameter of the hole 7b is stepped because the diameter of the hole 7b is about 0.2 to 0.3 mm, so that processing is difficult. Further, a raised portion 7c is provided on the upstream side of the hole 7b on the front surface of the second nozzle 7, so that the cross-sectional area of the tertiary gas passage 20 to be described later is reduced.
[0023]
A stepped portion 7e is provided at an edge of the outer peripheral surface of the body portion of the second nozzle 7 on the side of the torch 1, and a first cap 9 is locked to the stepped portion 7e and attached to the torch 1. 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. .
[0024]
A secondary gas passage hole 7d, which is a plurality of holes, is formed in the body of the second nozzle 7, and a second cap 10 is fitted on the outer periphery of the body of the second nozzle 7 and in front thereof. . That is, the second cap 10 has a gap with the first cap 9 to form a secondary gas supply path 16, and the nozzle from the secondary gas supply path 16 in the cap 3 through the secondary gas passage hole 7 d. A secondary gas can be supplied to the secondary gas passage 20 in the tank 2. The secondary gas passage hole 7d is formed at a predetermined angle from the radial direction of the cross-section of the torch 1, whereby the secondary gas passing through the secondary gas passage hole 7d is supplied to the secondary gas passage 19 while swirling. The
[0025]
A third nozzle 8 is fitted on the front surface of the second nozzle 7, and a tertiary gas passage 20 is formed with a gap between the second nozzle 7. Similarly to the first nozzle 6 and the second nozzle 7, the third nozzle 8 also has an orifice 8a at its tip, which is formed with a larger diameter than the other orifices 6a, 7a, A secondary gas and a tertiary gas are ejected.
[0026]
The barrel portion of the third nozzle 8 is provided with a tertiary gas passage hole 8b, and a step portion 8c is formed on the edge of the barrel portion outer peripheral surface on the front end side of the torch 1. The third nozzle 11 is locked to the torch 1 by fitting the third cap 11 to the stepped portion and attaching the third cap 11 to the torch body 1. The third cap 11 has a gap with the second cap 10 to form a tertiary gas supply path 17, and the tertiary gas is transferred from the tertiary gas supply pipe 14 in the main body of the torch 1 to the tertiary gas in the cap 2. The gas is supplied to the tertiary gas passage 19 in the nozzle via the supply passage 17 and the tertiary gas passage hole 8b, and is ejected together with the plasma jet.
[0027]
Here, as described above, since the raised portion 7c is located 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 at the opening of the hole 7b is rapidly expanded, the static pressure of the passing tertiary gas is reduced, and the secondary gas is sucked from the hole 7b. Accordingly, the tertiary gas entrains and mixes the secondary gas, and is ejected together with the plasma jet from the third orifice 8a.
[0028]
Further, since the hole 7a is formed at a predetermined angle from the radial direction in a plane perpendicular to the axial center of the torch 1, the secondary air flow ejected from the hole 7a is swirled while the tertiary gas It enters the passage 20. Therefore, the secondary gas and the tertiary gas are smoothly and rapidly mixed and ejected from the orifice 8a of the third nozzle 8 as a uniform mixed gas.
[0029]
With the configuration as described above, in the plasma torch 1 according to the present invention, the two kinds of gases supplied separately are mixed and mixed at the tip of the torch without mixing the two kinds of gases in advance. It has a configuration capable of ejecting gas. Further, since the injector structure is formed, it is possible to efficiently mix the secondary gas into the tertiary gas without requiring a high pressure for the secondary gas.
[0030]
Next, a second embodiment according to the present invention will be described with reference to FIG. Parts that are the same as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted. The plasma torch in FIG. 3 differs from the first embodiment only in the second nozzle 21.
[0031]
Similar to the first embodiment, the second nozzle 21 is fitted to the outer periphery and the front of the first nozzle 6, and has a gap between the front surface of the first nozzle 6 and the rear surface of the second nozzle 21. A secondary gas passage 19 is formed. A step portion 21d is formed on the conical front surface of the second nozzle 21, and the third nozzle 8 is fitted on the inner peripheral surface thereof.
[0032]
The step portion 21d is provided with a hole 21b that allows the secondary gas passage 19 in the nozzle 2 and the tertiary gas supply passage 17 in the cap 3 to communicate with each other. Therefore, a part of the secondary gas supplied to the secondary gas passage 19 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.
[0033]
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 a hole 24a is provided in the vicinity of the contact portion of the second cap 24 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 cross-sectional area of the tertiary gas supply passage 17 formed between the third cap 11 and the fitting is fit. It is configured to be
[0034]
That is, the tertiary gas supply path 17 forms an injector structure, and the supplied gas is temporarily compressed at the raised portion 24b and expanded at the opening of the hole 24a. As a result, the flow rate of the tertiary gas increases locally and the static pressure decreases, and the secondary gas suction efficiency can be increased and mixed with the tertiary gas.
[0035]
In the above embodiment, the injector structure is described as being provided in the first and third embodiments and not provided in the second embodiment. In any case, the injector structure is provided or It is possible to choose not to provide. 1 and FIG. 4, the hole is illustrated as a two-stage hole whose diameter changes. However, as shown in FIG. 2, a hole without a step may be used. Moreover, 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.
[0036]
Further, in the above embodiment, each gas is swirled by forming a hole and a passage hole located between each gas supply path and the passage with a predetermined angle from the radial direction of the cross section of the torch 1. Showed. However, the direction of turning and the presence or absence of turning are arbitrary and are not particularly limited.
[0037]
【The invention's effect】
By configuring as described above, the plasma torch according to the present invention can mix the secondary gas and the tertiary gas inside the tip of the torch. Further, by providing the injector structure, the secondary gas can be sucked by the tertiary gas, and the mixing efficiency can be increased. Moreover, the mixing after mixing can be made uniform by setting an angle to the hole for communicating the secondary gas with the tertiary gas.
[0038]
Therefore, independently supplied gas can be mixed at the nozzle tip, and even when the gas to be mixed is a flammable gas and a flammable gas such as hydrocarbon gas and oxygen, Safety can be improved.
[0039]
Moreover, 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 price can be reduced. In addition, since only one kind of gas passes through a single supply hose, the supply hose can be dedicated, making it easy to select a durable hose for the gas to be used and reducing the unit price. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a plasma torch tip according to a first embodiment.
FIG. 2 is an enlarged cross-sectional view of a tip portion of a plasma torch.
FIG. 3 is a sectional view of a plasma torch tip according to a second embodiment.
FIG. 4 is a cross-sectional view of a plasma torch tip according to a third embodiment.
[Explanation of symbols]
DESCRIPTION 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 channel
13 ... Secondary gas supply pipe
14 ... Tertiary gas supply pipe
15 ... Cooling water passage
16 ... Secondary gas supply path
17 ... Tertiary gas supply channel
18 ... Plasma gas passage
19 ... Secondary gas passage
20 ... Tertiary gas passage
20a ... Injector
21 ... Second nozzle according to the second embodiment
23 ... Second nozzle according to the third embodiment
24 ... Second cap according to the third embodiment

Claims (5)

A plasma torch for cutting by supplying a plasma gas, a secondary gas and a tertiary gas to a nozzle disposed at the tip of the plasma torch, and an electrode disposed at the center of the plasma torch, and between the electrodes A first nozzle member that forms a plasma gas passage, a second nozzle member that forms a secondary gas passage between the first nozzle member, and a third gas passage that forms a tertiary gas passage between the second nozzle member Three nozzle members, a first cap member fitted to the second nozzle member, a second cap member that forms a secondary gas supply path between the first cap member, and the second cap member And a third cap member that forms a tertiary gas supply path between
A plasma torch comprising a hole for communicating the secondary gas supply passage and the tertiary gas passage. 2. The hole according to claim 1, wherein the hole is provided in the second nozzle member, and the hole communicates the secondary gas supply path and the tertiary gas path via the secondary gas path. The plasma torch as described. The said hole is provided in said 2nd cap, This hole connects the said secondary gas supply path and the said tertiary gas path via the said tertiary gas supply path. Plasma torch. In the tertiary gas supply passage or the tertiary gas passage, an injector structure is formed by forming a cross-sectional area upstream of the gas supply passage from the hole narrower than the vicinity of the opening of the hole. The plasma torch according to claim 1, claim 2 or claim 3. The hole is formed at a predetermined angle from the radial direction in a plane perpendicular to the axis of the plasma torch, and is configured to swirl the gas passing through the hole. The plasma torch according to any one of claims 1 to 4.

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