JP2505783Y2 - Nozzle tip for plasma cutting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to improvement of a nozzle tip in a plasma cutting machine.

(Prior Art) In a plasma cutting machine, for example, as proposed in Japanese Patent Laid-Open No. 62-212060, working gas is converted into plasma gas by an arc and the plasma gas is jetted toward a material to be cut. As shown in FIG. 1, a nozzle tip (20) having a nozzle hole (21) is provided so as to face the electrode (11), and the entire cap (12) is provided. It is covered by. And
The plasma cutting machine (10) forms a plasma generation chamber between the electrode (11) and the nozzle tip (20), and the working gas is introduced into the generation chamber while the arc is blown to generate plasma gas. It is designed to eject from the nozzle hole (21) of the nozzle tip (20).

As described above, the nozzle tip (20) constituting the plasma cutting machine (10) must be capable of being energized to generate an arc, that is, have electrical conductivity. Is. Also, although water etc. is constantly supplied to the tip of the plasma cutting machine (10) to cool it, the plasmaized gas has a high temperature, so the nozzle tip (20) is particularly heat resistant. It is required to be formed of a material having

Many nozzle chips (20) of this type are generally made of metal such as copper. If the nozzle tip (20) is made of metal, not only the necessary conductivity can be obtained, but also the metal has good heat conduction, so that heating by cooling water or the like can be prevented. That is, it is possible to have a certain degree of heat resistance. However, the vicinity of the nozzle hole (21) of the nozzle tip (20) is in a very heated state because the plasma is ejected, and it is necessary to eject the plasma gas toward the material to be cut and exposed to the air. In particular, the surrounding oxygen is often caught in the surface of the nozzle hole (21) of the nozzle tip (20) by the jetted plasma gas, and dross (solvent iron) is attached at the time of cutting.

Therefore, in the conventional nozzle tip (20) made of metal, the temperature becomes high in the vicinity of the nozzle hole (21) and is exposed to oxygen, so that the oxidation cannot be avoided, and thus the nozzle is Hole (2
The nozzle tip (20) of this kind is inevitably replaced if it is used for several hours to several days, because the clogging of 1) occurs and it cannot be used. Also, nozzle tip (20)
The outside air may enter the inside of the to form an oxide film, which will be broken when the next arc occurs and not only will the nozzle hole (21) be clogged, but also the dross at the time of cutting. There is also a phenomenon that a so-called double arc is generated which causes the nozzle hole (21) to be damaged due to the adherence of
After all, the life of this type of nozzle tip (20) is very short.

There is a "plasma arc torch" as disclosed in Japanese Patent Laid-Open No. 1-99783, which is a conventional technique for suppressing the occurrence of double arc in order to prolong the life of the nozzle tip (20). According to the description in the scope of claims of the above-mentioned publication, this arc torch is that "a pilot arc is generated between a machining electrode and an orifice portion for plasma, and during machining, it is between the electrode and a workpiece. In a plasma arc torch for generating a plasma arc, the orifice member is made of a mechanical carbon material. "However, this solves the double arc problem described above. However, the oxidation of the "mechanical carbon material" forming the orifice member of this arc torch has not been improved yet.

Further, since a constant voltage is applied to this type of nozzle tip (20), a kind of discharge phenomenon occurs when this nozzle tip (20) contacts the workpiece or the like. Therefore, it is necessary to devise to prevent this. For example, in a general plasma cutting machine as shown in FIG. 1, the cap (12) does this. However, when this cap (12) is used, the nozzle tip (20) The tip part becomes large and it becomes difficult to process the inside of the corner of the work material, the cutting marking line is not visible and the cutting linearity disappears, and it must be removed every time the nozzle tip (20) is replaced. Therefore, the work must be troublesome. That is, when replacing the nozzle tip (20), for example, it is convenient to have a structure in which the cap (12) does not have to be removed.

Therefore, the inventor of the present invention has conducted various studies on how to make the nozzle tip (20) of this type longer in life and more efficient in working. As a result, the present invention was completed.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and the problems to be solved are to extend the life of the nozzle tip (20) and improve the replacement efficiency.

And, first of all, the object of the invention according to the first claim is that durability is ensured by preventing the nozzle hole (21) from being clogged with an oxide while ensuring a predetermined conductivity and heat resistance. Of course it can be improved,
The object is to provide a nozzle tip (20) in which only a necessary part can be replaced. Further, the object of the invention according to the second claim is to have the same effect as that of the invention according to the above-mentioned first claim, as well as the insulating property of the nozzle tip (20) itself. Nozzle tip (2) that can improve the durability by increasing the power consumption and preventing the consumption of the nozzle tip (20) itself due to the discharge between the workpiece and the workpiece.
0) to provide.

(Means for Solving the Problem and Its Action) In order to solve the above problems, the means adopted in the invention of the first claim is that "a plasma generating chamber is formed facing the electrode (11). A nozzle tip (20) for a plasma cutting machine (10) having a nozzle hole (21) for injecting plasma gas generated in a plasma generation chamber, the nozzle tip (20) having a mounting opening (22). A graphite chip body (20A) having the above, a graphite chip small piece (20B) having the nozzle hole (21) attached to a mounting opening (22) of the chip main body (20A), and the chip small piece ( 20B)
And a pyrolytic carbon coating (23) formed on at least the surface of the nozzle hole (21) near the nozzle tip (20).

That is, in the nozzle tip (20) according to the present invention, the base of the tip body (20A) and the tip small piece (20B) is made of graphite, and the pyrolytic carbon is present at least in the vicinity of the nozzle hole (21) of the tip small piece (20B). The pyrolytic carbon coating (23) is formed of, and it is preferable that graphite having isotropy, high density and high strength is adopted as this graphite. The reason is that the nozzle tip (20) may come into contact with the material to be cut at the tip, and it is preferable that the nozzle tip (20) has a predetermined strength so as not to be damaged in that case.

Therefore, the graphite nozzle tip (20) has the excellent conductivity and heat resistance of graphite itself, and in the vicinity of the nozzle hole (21) of the tip small piece (20B). Even if graphite oxidizes in
This changes to carbon gas or the like and flies to the outside, so that the nozzle hole (21) is not clogged at all. Since the oxidation of graphite in this case is extremely small, the entire nozzle tip (20) will not disappear within a short period of time.

Further, the nozzle tip (20) according to the present invention is not an integrated body, but it is necessary to mount the tip small piece (20B) to the mounting opening (22) of the tip body (20A). . The reason is this kind of nozzle tip (20)
In general, since the consumption in the vicinity thereof is faster than that in the other portions, it is advantageous to adopt a structure in which only the portion in the vicinity of the nozzle hole (21) can be replaced. Therefore, in the present invention, the chip piece (20
B) may be attached by screwing it into the mounting opening (22) of the chip body (20A). If this chip small piece (20B) is consumed, remove only this chip small piece (20B). It can be exchanged with other new chip pieces (20B). As a result, the tip piece (20B) is consumed and the work for replacing it is very easy, and the cost of this type of nozzle tip (20) is reduced.

As a method of forming a pyrolytic carbon coating (23) made of pyrolytic carbon in the vicinity of the nozzle hole (21) of the chip piece (20B) constituting the nozzle chip (20), for example, various commonly used chemistries are used. It can be performed by the vapor deposition method (CVD). The graphite is heated to 800 to 2600 ° C, and hydrocarbons or halogenated hydrocarbons are brought into contact with graphite in the presence of hydrogen gas to form graphite with many pores. Form a dense layer of pyrolytic carbon. These reactions are carried out under normal pressure or reduced pressure, but considering the uniformity and smoothness of the pyrolytic carbon coating (23), it is desirable to carry out under reduced pressure, especially 300 Torr or less. The thickness of the coating film (23) made of pyrolytic carbon is preferably 10 μm to 500 μm. The reason is 10μ
This is because if it is less than m, sufficient wear resistance cannot be obtained.
This is because if the thickness is 0 μm or more, cracks are likely to occur in the pyrolytic carbon coating (23) due to the difference in thermal expansion from graphite.
Above all, it is advantageous that the thickness of the coating film (23) is about 50 μm, because it is easy to form and the required wear resistance is obtained.

The nozzle tip (20) having the chip piece (20B) having the pyrolytic carbon coating (23) as a constituent member has excellent conductivity and heat resistance, and is easily exposed to oxygen. Since the part is covered with the pyrolytic carbon coating (23) which is difficult to oxidize, the oxidation is hard to be suppressed as much as possible. Therefore, no oxide that would clog the nozzle hole (21) of the nozzle tip (20) is generated.

The chip body (20A) and chip small piece (2
The average coefficient of thermal expansion of the graphite that constitutes (0B) is 1.
The anisotropic ratio was 3 to 7.0 × 10 ⁻⁶ / ° C. and 1.25 or less.
Thus, the average coefficient of thermal expansion (average value of the coefficient of thermal expansion in a temperature atmosphere of 20 ° C to 400 ° C) is 1.3 to 7.0 × 10 ^-6 /
The temperature of graphite is adopted because the nozzle tip (20) based on this graphite is placed in a heat cycle from room temperature to a temperature locally heated by plasma arc heat. This is also to prevent a large change due to thermal expansion. This prevents, for example, the pyrolytic carbon coating (23) formed on the chip piece (20B) from peeling from the base material made of graphite.

Further, the graphite having an anisotropic ratio of 1.25 or less, when the heat cycle described above is repeated, makes the thermal stress generated therein extremely small, and thus damage of the graphite itself is prevented. is there.

On the other hand, in the nozzle chip (20) according to the second claim, the chip small piece (20B) of the nozzle chip (20) according to the above-mentioned first claim, a part of which is the chip body (20A).
Of the chip piece (20B), and an insulating coating (24) is formed on at least the outer surface of the projecting portion of the chip piece (20B). In this way, the tip small piece (20B) is first projected from the mounting opening (22) of the tip body (20A) because the tip small piece (20B) has the nozzle hole (21). Small piece (20B)
This is because it is necessary to eject the plasma gas from the nozzle hole (21) from the tip of the nozzle tip (20).
That is, if the chip small piece (20B) having a relatively small diameter is projected, the work can be easily and accurately performed even in a place where the portion to be plasma-processed is narrow.
If this happens, the chip pieces (20B) will easily come into contact with the material to be cut, etc., and discharge to other parts via the chip pieces (20B) will be easier. However, this discharge is prevented by this chip pieces. It is the insulating film (24) formed on at least the outer surface of the protruding portion of (20B).

Further, since a part of the tip small piece (20B) of the nozzle tip (20) is projected from the tip body (20A), the protruding portion of the tip small piece (20B) is pinched with a finger or the like. If rotated, it can be easily removed from the mounting opening (22) of the chip body (20A). Therefore, the nozzle tip (20) according to the second claim
Also, in this case, it is easy to replace the chip piece (20B).

(Embodiment) Next, each invention will be described in detail according to an embodiment shown in the drawings.

FIG. 2 shows a cross section of a nozzle tip (20) according to the invention of the first claim. The nozzle tip (20) is a graphite tip body (20A) and this tip body (20A).
Graphite chip pieces (20
B) and. The main body of the chip body (20A) and chip chip (20B) is formed by kneading coke or carbon fine powder with a binder component such as tar pitch to form a high density product, and firing it by a conventional method to obtain graphite. The material is formed by cutting this graphite material into a predetermined shape. A tip body (20A) that constitutes the nozzle tip (20) shown in FIG.
The concrete size of is about 15 mm in diameter, 8 mm in inner diameter, and 1 in length.
A mounting part having a brim is formed with a size of about 5 mm, and a mounting port (22) having a diameter of 9 mm is formed at the center thereof. A chip piece (20B) having a thickness of about 2.5 mm is screwed into the mounting opening (22), and the chip piece (20B) is also made of graphite. In addition, these chip bodies (20
A) and the graphite that composes the chip (20B) have a coefficient of thermal expansion of 3.0 × 10 ^-6 / ° C and an anisotropic ratio of 1.20. A nozzle with a diameter of 1.3mm is provided in the center of the chip (20B). A hole (21) is provided.

Further, a pyrolytic carbon coating (23) having a thickness of about 50 μm is formed on the surface of the chip small piece (20B) other than the screwed portion, and the pyrolytic carbon coating (23) forms the chip small piece (20B). It protects the above-mentioned graphite, which is the substrate. The chip piece (20B) is screwed into the mounting opening (22) in a state where it is completely inside the mounting opening (22) of the chip body (20A).

FIG. 3 shows another embodiment of the device according to the second claim. In this nozzle tip (20), an insulating film (24) is formed on the surface other than its mounting portion. is there.

An embodiment of the nozzle tip (20) according to the second claim is shown in FIG. That is, in the nozzle tip (20) of FIG. 4, the tip of the tip small piece (20B) is formed into a bullet shape, and the tip of the tip small piece (20B) is attached to the mounting opening (22) on the tip body (20A) side. ) Is screwed in such a manner as to project from here. An insulating film (24) having a thickness of about 500 μm is formed on the surface of the protruding portion of the chip piece (20B). The tip small pieces (20B) are covered with a pyrolytic carbon coating (23) except for the threaded portion.

Then, as a comparison, a copper nozzle tip having the same shape as that shown in FIG. 2 was formed, and an experiment of using this and the nozzle tip (20) of the present invention was tried. In this case, a plasma cutting machine (10) with oxygen plasma is used, with a current of 80 amps, width 200 mm, thickness 8 mm, length 20.
A 00 mm stainless plate was intermittently cut at a cutting speed of 600 to 1000 mm / min for 1 hour by continuous operation by manual operation. As a result of measuring the diameter of the nozzle hole (21) of each nozzle tip after cutting after each one-hour work, the result is as shown in FIG. 5, and the nozzle tip (20) formed of copper is It reached the hole diameter that cannot be used with a plasma cutting machine with a capacity of 80 amps.

As shown in FIG. 5, the nozzle tip (20) according to the present invention, when compared with the nozzle tip (20) made of copper,
It can be understood that the life is about double or more, which is very excellent.

(Effects of the Invention) As described above, the nozzle tip (20) according to the first claim has a graphite chip body (20A) having a mounting port (22) and a mounting port of this chip body (20A). A graphite chip piece (20B) mounted on (22) and having the nozzle hole (21), and a pyrolytic carbon coating formed on at least the surface of the chip piece (20B) in the vicinity of the nozzle hole (21) ( 23), it has sufficient conductivity and heat resistance as a plasma nozzle, and even if it is oxidized, it does not generate foreign matter that may cause clogging of the nozzle hole (21). , No dross (molten iron) adheres when cutting, and a nozzle tip with extremely excellent durability (2
0) can be provided. Moreover, since the nozzle tip (20) made of this graphite can be formed by ordinary graphite processing, it can be manufactured very easily, and the nozzle hole (20B) formed in the tip small piece (20B). Since a pyrolytic carbon coating (23) that makes graphite difficult to oxidize is formed around the vicinity of (21), it is possible to prevent oxidation of graphite as much as possible and to make it excellent in durability. You can do it.

Moreover, according to the nozzle tip (20) of the second claim, the nozzle tip (20A) and the tip small piece (20B) can be disassembled and attached to each other, so that the nozzle hole (21) is easily worn. Since only the small tip piece (20B) in the vicinity needs to be replaced, the replacement workability can be significantly improved, and the cost of the entire nozzle tip (20) can be reduced.

In addition to the nozzle chip (20) according to the second claim having the same effect as the nozzle chip (20) according to the first claim, the chip chip (20B) has a chip body (20B).
While protruding from the mounting opening (22) of A),
Since the insulator coating (24) is formed on at least the outer surface of the protruding portion of the tip piece (20B), the nozzle tip (20)
It is possible to make it easier to perform work using, and to prevent discharge even if the protruding portion of the chip piece (20B) comes into contact with another object during the work. Therefore, the durability of the nozzle tip (20) according to the second aspect can be further improved.

[Brief description of drawings]

1 is an enlarged partial sectional view of a torch portion of a plasma cutting machine to which a nozzle tip according to the present invention is applied, FIG. 2 is an enlarged sectional view of a nozzle tip according to the first claim, and FIG. Is an enlarged sectional view showing another embodiment, FIG. 4 is an enlarged sectional view of the nozzle tip according to the second claim, and FIG. 5 is a comparative test of the nozzle tip according to the present invention and a nozzle tip made of copper. It is a graph which shows a result. Explanation of code 10 …… Plasma cutting machine, 11 …… Electrode, 20 …… Nozzle tip, 20A …… Tip body, 20B …… Tip small piece, 21 …… Nozzle hole, 22 …… Mounting port, 23 …… Pyrolysis Carbon coating, 24 ……
Insulator coating.

Claims (2)

(57) [Scope of utility model registration request] 1. A plasma generating chamber is formed facing the electrode,
A nozzle chip for a plasma cutting machine having a nozzle hole for injecting plasma gas generated in the plasma generation chamber, the nozzle chip being a graphite chip body having a mounting port, and mounting the chip body. A nozzle tip comprising a graphite chip piece attached to a mouth and having the nozzle hole, and a pyrolytic carbon coating formed on at least a surface of the chip piece near the nozzle hole. 2. The chip small piece has a part thereof protruding from a mounting opening of the chip body, and an insulating film is formed on at least an outer surface of the protruding part of the chip small piece. The nozzle tip according to claim.