JPH0732156A - Nozzle of plasma torch - Google Patents

Abstract

PURPOSE:To secure the coaxiality of the orifice to eject the plasma arc and the orifice to eject the secondary air flow, to reduce the adhesion of the molten metal as much as possible, and to improve the inclination of the cut surface. CONSTITUTION:The axes of a first orifice 5 and a second orifice 6 are coincided, and an inner nozzle member 1 is driven into an outer nozzle member 2 to be integratedly mounted by the adhesive or screws to constitute the nozzle A of the same potential. A passage 7 to flow the gas to form the secondary air flow is formed between the inner nozzle member 1 and the outer nozzle member 2, and a plurality of holes 8 are formed in the outer nozzle member 2. The nozzle A is mounted on a torch body 10 by an inner cap 13, and protected by a guard cap 14. Coaxiality of the first and second orifices are guranteed even when the orifices are used for a long time, and no molten metal is adhered to the surface of the nozzle A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma torch nozzle for injecting a secondary air stream along the circumference of a plasma arc.

[0002]

2. Description of the Related Art A plasma torch for cutting a material such as a steel plate or a stainless steel plate is disclosed in Japanese Patent Publication No. 2-504603.
As disclosed in Japanese Patent Publication No. 5-501081 and the like, a gas such as nitrogen gas is injected as a secondary air stream along a plasma arc injected from an orifice toward a material to be cut. .

In the above technique, a shield electrically insulated from the nozzle is provided on the surface side of the nozzle, and a gas is circulated between the shield and the nozzle to cool the nozzle and a secondary air stream can be jetted. It was done. Therefore, even if the molten metal generated when cutting the material to be cut adheres to the surface of the shield, the double arc can be prevented from occurring.

It is known that the secondary air stream jetted along the plasma arc contributes to the improvement of the quality of the cut surface. In particular, when the secondary air flow is a swirl flow, it is possible to improve the inclination of the cut surface, which is a characteristic of plasma cutting.

[0005]

The electrode attached to the plasma torch wears out as the usage time increases, so it is necessary to replace it periodically. Therefore, in the technique of the above publication in which the nozzle and the shield are configured as different members,
Each time the electrodes are replaced, the nozzle and shield must be attached and detached from the plasma torch, making it difficult to match the axis of the plasma arc (axis of the nozzle orifice) with the swirl center of the secondary air flow (axis of the exit orifice). Therefore, there is a problem that the quality of the cut surface by the plasma arc, especially the improvement of the inclination of the cut surface cannot be achieved by the above technique.

When the secondary air flow is swirled and ejected from the orifice, the orifice and the position of the hole for supplying the gas serving as the secondary air flow to the flow passage formed by the outer nozzle member and the inner nozzle member are made to have a fixed relationship. There is a problem in that it is difficult to effectively use the secondary air flow unless it is held.

The object of the present invention is to ensure the coaxiality of the orifice for injecting the plasma arc and the orifice for injecting the secondary air flow, to reduce the adhesion of the molten metal as much as possible, and further to improve the inclination of the cut surface. It is to provide a nozzle of a plasma torch capable of performing.

[0008]

In order to solve the above-mentioned problems, a nozzle of a plasma torch according to the present invention is a nozzle of a plasma torch which is arranged so as to coincide with the axis of an electrode and ejects a plasma arc. An inner nozzle member having a first orifice for passing a plasma arc and forming a pilot arc by arc discharge between the first orifice and an electrode, and a second orifice for passing a plasma arc and a secondary air flow, and the inner nozzle. An outer nozzle member that forms a flow passage through which a gas that becomes a secondary air flow passes, and the outer nozzle member is provided on the outer periphery of the inner nozzle member by aligning the axes of the first orifice and the second orifice. Is directly attached and is integrally configured.

In the nozzle of the plasma torch, a cylindrical portion is formed at the tip of the outer nozzle member, a step portion is formed at the base of the cylindrical portion, and the cylindrical portion is fitted into the hole formed in the cap. At the same time, it is preferable that the cap can be screwed and fixed to the main body of the plasma torch.

Further, in the above-mentioned plasma torch nozzle, a hole having a predetermined turning angle with respect to the axis of the second orifice of the nozzle member is formed at a predetermined position of the outer nozzle member, and the hole is inserted through the hole. It is preferable to be configured so as to be able to supply a gas that becomes a secondary air flow.

[0011]

According to the nozzle of the plasma torch described above, the first orifice formed in the inner nozzle member and the second orifice formed in the outer nozzle member are coaxial with each other for a long period of time, and the plasma arc is generated from the second orifice. A secondary air flow along the arc can be injected.

That is, since the outer peripheral nozzle member is mounted on the outer periphery of the inner nozzle member so that the axial centers of the first orifice and the second orifice are aligned with each other, the outer nozzle member is integrally formed, so that the electrode mounted on the torch body is replaced. Even in the case, it is not necessary to separate the inner nozzle member and the outer nozzle member that form the nozzle. Therefore, the coaxiality of the first orifice and the second orifice can be ensured.

Further, since the gas flow passage for forming the secondary air flow is formed between the outer circumference of the inner nozzle member and the inner circumference of the outer nozzle member, by supplying the gas through the flow passage, this gas can be supplied. Can be injected as a secondary air flow from the second orifice.

Further, a cylindrical portion is formed at the tip of the outer nozzle member, and a step portion is formed at the base of the cylindrical portion, and the cylindrical portion is fitted into the hole formed in the cap, and the cap is attached to the main body of the plasma torch. When the nozzle can be fixed by screwing, the area of the exposed portion of the nozzle can be made as small as possible, and thus the amount of molten metal deposited can be made as small as possible. You can

Further, a hole having a predetermined turning angle with respect to the axis of the second orifice of the nozzle member is formed at a predetermined position of the outer nozzle member, and a gas which becomes a secondary air flow is supplied through the hole. When configured to obtain the gas, it becomes possible to swirl the gas by supplying the gas to the flow passage formed between the outer nozzle and the inner nozzle.
The secondary airflow ejected from the orifice can be a swirl flow. Therefore, the inclination of the cut surface can be improved.

[0016]

EXAMPLE An example of the nozzle of the plasma torch will be described below with reference to the drawings. FIG. 1 is a sectional view of the nozzle,
FIG. 2 is a developed view of parts constituting the nozzle, and FIG. 3 is a sectional view for explaining the structure of the plasma torch.

In the figure, a nozzle A is an inner nozzle member 1.
The outer nozzle member 2 is integrally mounted on the outer circumference of the tip portion of the. The inner nozzle member 1 and the outer nozzle member 2 are firmly integrated by a method such as press fitting or bonding. The nozzle A is configured as a single member, and even if the inner nozzle member 1 and the outer nozzle member 2 do not separate during use and the electrodes are replaced, the inner nozzle member 1 and the outer nozzle member 2 There is no need to separate the member 2.

The inner nozzle member 1 is formed in a funnel shape as a whole, and the outer surface thereof faces from the rear end side (right side in the figure, the same applies hereinafter) to the tip side (left side in the figure, the same applies below). A body portion 1a, a seal portion 1b, a tubular portion 1c, and a taper portion 1d are formed in this order. A groove 3 for mounting an O-ring (not shown) is formed in the seal portion 1b, and a step portion 4 is formed at the base of the tubular portion 1c.

On the inner surface of the inner nozzle member 1, a parallel portion 1e and a tapered portion 1f are formed in this order from the rear end side to the front end side. A first orifice 5 is formed continuously with the tip of the tapered portion 1f and inside the tubular portion 1c.

The inner nozzle member 1 has a function of arc-discharging with the electrode 9 shown in FIG. 3 to form a pilot arc. For this reason, the inner nozzle member 1 is formed of copper or a copper alloy, which is a metal material having electrical conductivity and appropriate thermal conductivity.

The outer nozzle member 2 is formed in a cup shape as a whole, and a body portion 2a, a cylindrical portion 2b, and a taper portion 2c are formed on the outer surface in order from the rear end side to the front end side. A step portion 2d is formed at the base portion of the tubular portion 2b and at the connecting portion with the body portion 2a. Similarly, a parallel portion 2e and a tapered portion 2f are formed on the inner surface of the outer nozzle member 2, and a second orifice 6 is formed continuously with the tip of the tapered portion 2f and inside the tubular portion 2b.

The outer nozzle member 2 is integrally mounted on the outer circumference of the inner nozzle member 1. In this embodiment, the step portion 4 formed on the inner nozzle member 1 is configured to be fitted and integrated with the outer nozzle member 2.

Therefore, the parallel portion 2e formed on the inner surface of the outer nozzle member 2 has a value substantially equal to the diameter of the step portion 4 formed on the outer surface of the inner nozzle member 1. That is, when the inner nozzle member 1 and the outer nozzle member 2 are integrated by driving, the diameter of the step portion 4 and the diameter of the parallel portion 2e are formed to have the same value, and when the both are integrated by adhesion, The diameter of the portion 4 is formed to have a value slightly smaller than the diameter of the parallel portion 2e. Further, the inner nozzle member 1 can be screwed into the outer nozzle member 2 to be integrated, and in this case, preset steps are formed on the step portion 4 and the parallel portion 2e.

The diameter of the cylindrical portion 1c of the inner nozzle member 1 is formed to be smaller than the diameter of the step portion 4, and the taper portion 1d is smaller than the taper portion 2f of the outer nozzle member 2. Is formed. Therefore, a passage 7 is formed between the parallel portion 2e and the tubular portion 1c and between the tapered portion 2f and the tapered portion 1d.

A plurality of holes 8 are formed in the body portion 2a of the outer nozzle member 2 at a position where the distance from the rear end surface of the member 2 is larger than the height of the step portion 4 of the inner nozzle member 1.
The hole 8 is for supplying the gas forming the secondary air flow to the passage 7 formed between the inner nozzle member 1 and the outer nozzle member 2, and is formed obliquely from the outer surface to the inner surface. That is, the hole 8 is formed with a swirl angle with respect to the axis of the second orifice 6, so that the gas supplied through the hole 8 flows in the passage 7 as a swirl flow.

The material forming the outer nozzle member 2 is not particularly limited. However, considering the thermal expansion due to the radiant heat of the plasma arc, it is preferable to use the same metal as the material forming the inner nozzle member 1. That is, by forming the inner nozzle member 1 and the outer nozzle member 2 from the same metal material, even if these members 1 and 2 are thermally expanded by the radiant heat of the plasma arc, driving, bonding and screwing are performed. It is possible to maintain the integration of the two in a strong state by the above.

Further, the inner nozzle member 1 and the outer nozzle member 2
When they are made of the same metal and are integrated, these nozzle members 1 and 2 have the same potential. Therefore, when the pilot arc is formed, the base point of the arc sequentially moves from the electrode 9 to the inner nozzle member 1 to the outer nozzle member 2,
It is possible to obtain good ignitability. Particularly, it is preferable that the pilot arc has good ignitability when each of the orifices 5 and 6 has a small diameter.

Further, it is possible to exhibit the same effect when forming the main arc. That is, since the outer nozzle member 2 has the same potential as the inner nozzle member 1, the position closest to the surface of the workpiece is the end surface of the outer nozzle member 2. Therefore, compared with the case where the outer nozzle member is made of a material having an insulating property, the distance from the surface of the workpiece is the end surface of the inner nozzle member 1, compared to the workpiece of the plasma torch. It is possible to increase the distance. Therefore, the effect of reducing the adhesion of spatter etc. to the plasma torch is derived.

In the nozzle A constructed as described above,
The plasma arc and the working gas are injected from the first orifice 5, and the plasma arc and the working gas are emitted from the second orifice 6.
In addition to the working gas, the swirled secondary airflow is injected. Therefore, in order to improve the quality of the cut surface with respect to the material to be cut, the diameter ratio of the first orifice 5 and the second orifice 6, the separation distance L, the injection angle, the diameter of the second orifice 6 and the nozzle of the inner nozzle member 1 are used. Each has a delicate relationship with the diameter of the tip.

Similarly, the distance from the nozzle tip of the hole 8 formed in the outer nozzle member 2 and the formation site have an extremely delicate relationship.

The present inventor experimentally determined that the first
The diameter of the orifice 5 and the diameter of the second orifice 6 are 1 pair in area ratio.
It is preferably in the range of 1.2 to 1: 5, the separation distance L between the two is preferably in the range of 0.2 mm to 5 mm, and the injection angle of the secondary air flow with respect to the plasma arc is in the range of 5 degrees to 175 degrees. Preferably, the second
It has been found that the difference between the diameter of the orifice 6 and the tip diameter of the inner nozzle member 1 is preferably in the range of -0.5 mm to 1 mm.

The distance from the nozzle tip of the hole 8 formed in the body portion 2a of the outer nozzle member 2 is preferably 20 mm or less, and is preferably formed at a position having an outer diameter of 40 mm or less. There was found.

That is, the inner nozzle member 1 in the nozzle A
By forming the outer nozzle member 2 and the outer nozzle member 2 in the above relationship, the secondary airflow injected from the second orifice 6 can be swirled in a good state, and the inclination of the cut surface can be improved. Is.

The nozzle A constructed as described above is mounted on the torch body 10 so as to face the electrode 9. The electrode 9 is screwed onto the torch body 10 and is detachably attached. The electrode 9 is provided with a centering stone 12 which is made of an electrically insulating material and which swirls the working gas to a predetermined position and supplies it to a chamber 11 formed around the electrode 9. The outer diameter of the centering stone 12 has a value substantially equal to the diameter of the parallel portion 1e of the inner nozzle member 1 in the nozzle A, and the nozzle A is fixed to the torch body 10 at the same time.

The nozzle A is fixed to the torch body 10 via the inner cap 13 and the guard cap 14. That is, a hole having a size corresponding to the outer diameter of the seal portion 1b of the inner nozzle member 1 of the nozzle A is formed at the tip of the inner cap 13, and the nozzle A is fitted into the hole, By screwing the inner cap 13 onto the torch body 10, the nozzle A
Is fixed to the torch body 10. By mounting the inner cap 13 on the torch body 10, a cooling water passage 15 is formed between the cap 13 and the torch body 10.

Therefore, the cooling water supplied from the cooling water supply passage (not shown) provided in the torch body 10 is supplied to the inner cap 13
Flows through a cooling water passage 15 formed between the torch body 10 and the torch body 10 and is drained from a drainage passage (not shown). It is possible to cool the torch body 10 and the nozzle A while the cooling water is flowing. The electrode 9 is a cooling water passage formed in the torch body 10.
It is cooled by the cooling water flowing through 17.

The guard cap 14 has a function of forming a passage 16 through which a gas forming a secondary air flow is circulated between the guard cap 14 and the inner cap 13 and protects the nozzle A from the molten metal generated when the material to be cut is cut. It has a function to do. A hole having a diameter substantially equal to the outer diameter of the tubular portion 2b of the outer nozzle member 2 in the nozzle A is formed at the tip of the guard cap 14.

Therefore, when the nozzle A is fixed to the torch body 10 by the inner cap 13, and then the guard cap 14 is fitted into the nozzle A and mounted on the torch body 10, the inner surface of the tip of the guard cap 14 becomes the nozzle A. It is possible to contact the step portion 2d of the outer nozzle member 2, form a passage 16 between them, and protect the nozzle A.

Therefore, the gas forming the secondary air flow supplied from the gas supply passage 18 formed in the torch main body 10 passes through the passage 16
A passage 7 formed inside the nozzle A through a hole 8 formed in the outer nozzle member 2 in the nozzle A
And is ejected from the second nozzle 6. It is possible to cool the nozzle A in the course of the gas flow.

Further, by reducing the outer diameter of the cylindrical portion 2b formed on the outer nozzle member 2 in the nozzle A,
It is possible to reduce the surface area of the nozzle A protruding and exposed from the guard cap 14 as much as possible, and prevent or reduce the adhesion of the molten metal generated when the material to be cut is cut to the nozzle A. It is possible.

In the nozzle A, as shown in FIG. 4 (A), the secondary arc 20 is jetted by swirling in the direction of arrow a around the plasma arc 19, and the plasma torch is moved in the direction of arrow b. When the material to be cut is cut by the cutting, the vector of the arrow a (arrow a1) that opposes the direction of the arrow b, which is the moving direction, cancels each other, and as shown in FIG. The inclination of the surface 21 is improved.

Therefore, the cutting speed (vector in the direction of arrow b) preset according to the material and plate thickness of the material to be cut
By setting the flow velocity of the secondary air flow 20 so as to be able to oppose to the above, it is possible to form the cut surface 21 vertically. In addition, it is possible to improve the quality of the cut surface by setting the swirling direction of the secondary air flow according to the position of the surface on the product side with respect to the traveling direction of cutting.

However, the axial center of the plasma arc 19 and the secondary air flow
If the axes of 20 do not match, the vector balance of the secondary air flow 20 with respect to the plasma arc 19 will be lost and
It will be difficult to improve the slope of 21.

[0044]

As described above in detail, in the nozzle of the plasma torch according to the present invention, the outer peripheral nozzle member is directly attached to the outer periphery of the inner nozzle member so that the axes of the first and second orifices are aligned with each other. Since the electrodes are integrally formed, the coaxiality of the first and second orifices is not deteriorated even when the nozzle is attached and detached when the electrode attached to the plasma torch is replaced and the nozzle is affected by heat. For this reason,
It is possible to improve the quality of the cut surface and maintain it stably.

Further, a cylindrical portion is formed at the tip of the outer nozzle member constituting the nozzle, and a step portion is formed at the base of the cylindrical portion, and the cylindrical portion is fitted into the hole formed in the cap and fixed to the torch body. By doing so, it is possible to reduce the exposed area of the nozzle as much as possible, and prevent or reduce the adhesion of molten metal to the nozzle that occurs during cutting.

In addition, the hole formed in the outer nozzle member is
Since it is formed with a predetermined swirl angle with respect to the axis of the orifice, it has a feature that the secondary airflow can swirl in a good state and can be jetted from the second orifice.

[Brief description of drawings]

FIG. 1 is a sectional view of a nozzle.

FIG. 2 is a development view of components that form a nozzle.

FIG. 3 is a cross-sectional view illustrating the configuration of a plasma torch.

FIG. 4A is a plan view illustrating a relationship between a plasma arc and a secondary air flow, and FIG. 4B is a view illustrating a state of a cut surface.

[Explanation of symbols]

 A Nozzle 1 Inner nozzle member 2 Outer nozzle member 1a, 2a Body part 1c, 2b Cylindrical part 1e, 2e Parallel part 4, 2d Step part 5 1st orifice 6 2nd orifice 7 Passage 8 hole 9 Electrode 10 Torch body 13 Inside Cap 14 Guard cap 16 Passage 19 Plasma arc 20 Secondary air flow 21 Cut surface

Claims (6)

[Claims] 1. A nozzle of a plasma torch, which is arranged so as to coincide with an axis of an electrode and ejects a plasma arc, has a first orifice for passing the plasma arc, and arc-discharges with the electrode. An outer nozzle having an inner nozzle member that forms a pilot arc and a second orifice that allows a plasma arc and a secondary air flow to pass therethrough, and that forms a flow passage between the inner nozzle member and a gas that serves as a secondary air flow. Nozzle of the plasma torch, characterized in that the first orifice and the second orifice are aligned and the outer nozzle member is directly attached to the outer circumference of the inner nozzle member. 2. A cylindrical portion is formed at the tip of the outer nozzle member, and a step portion is formed at the base portion of the cylindrical portion, the cylindrical portion is fitted into a hole formed in a cap, and the cap is attached to the main body of the plasma torch. The nozzle of the plasma torch according to claim 1, wherein the nozzle is configured to be screwed and fixed to the nozzle. 3. A hole having a predetermined turning angle with respect to the axis of the second orifice of the nozzle member is formed at a predetermined position of the outer nozzle member, and a gas to be a secondary air flow is supplied through the hole. The nozzle of the plasma torch according to claim 1 or 2, wherein the nozzle is configured to be capable of performing. 4. The nozzle of the plasma torch according to claim 3, wherein the position where the hole is formed is between 20 mm and the tip of the outer nozzle member. 5. The nozzle of the plasma torch according to claim 3, wherein the position where the hole is formed is a portion having an outer diameter of 40 mm or less of the outer nozzle member. 6. In the relationship between the diameter of the first orifice of the inner nozzle member and the diameter of the tip of the nozzle member and the diameter of the second orifice of the outer nozzle member, the diameter of the first orifice is equal to the diameter of the second orifice. 4. The nozzle of the plasma torch according to claim 3, wherein the nozzle is small or small and the difference between the diameter of the second orifice and the tip diameter of the inner nozzle member is in the range of -0.5 mm to 1 mm.