JPH11192557A - Plasma cutting method and plasma cutting torch - Google Patents

Abstract

[PROBLEMS] To reduce the range of thermal influence caused by a plasma arc generated in a material to be cut when a plasma cutting method is performed, and improve cutting quality. A cooling gas is jetted from a cutting torch toward a material to be cut in the vicinity of a cutting portion which is a melting portion of a base material formed on the material to be cut by a plasma arc. And cool. As the cooling gas 5, a carbon dioxide gas or a mixed gas of a carbon dioxide gas and a reducing gas (for example, hydrogen gas) is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma cutting method which is advantageous for cutting a material having a relatively large thickness, and a plasma cutting torch for performing the method.

[0002]

2. Description of the Related Art In plasma cutting, an ultra-high temperature plasma arc is jetted toward a material to be cut, the material to be cut is melted by the heat of the plasma arc, and the molten material is formed into a base material by the energy of the plasma arc. By moving the plasma arc while excluding it from the workpiece, a continuous groove is formed in the material to be cut and the material is cut. That is, the plasma cutting method depends on the heat and injection energy of the plasma arc.

For this reason, the influence of heat cannot be ignored in the plasma cutting method. That is, the temperature of the plasma arc is an extremely high temperature of about 30,000 degrees Celsius, and when this plasma arc is sprayed on the material to be cut, the material to be cut is heated over a wide range around the part to be cut (cutting part). Is increased, and as the temperature is increased, the metallurgical surface or the quality of the cut surface is affected.

[0004]

In order to reduce the influence of the temperature, it is assumed that the material to be cut is submerged or that water is sprayed around the cut portion. However, the method of submerging the material to be cut has a problem that the size of the material to be cut is regulated by the size of a water tank for storing water, and the method of jetting water has a problem of treating the jetted water.

[0005] In addition, both methods have a problem that both the front and back surfaces and the cut surface of the material to be cut are oxidized.

An object of the present invention is to provide a plasma cutting method capable of locally cooling the vicinity of a cut portion of a material to be cut and preventing the material to be cut from being oxidized. It is to provide a plasma cutting torch to perform.

[0007]

According to the present invention, there is provided a plasma cutting method for cutting a material to be cut by injecting a plasma arc toward the material to be cut. In addition, a cooling gas is injected in the vicinity of a portion of the workpiece to which a plasma arc is injected to cool the workpiece.

In the above-mentioned plasma cutting method, a cooling gas is injected into the vicinity of a plasma arc injection portion of the material to be cut, so that the surface of the material to be cut is cooled while cutting the material to be cut. You can do it. For this reason, it is possible to narrow the range of temperature rise centering on the cut portion of the material to be cut, thereby limiting the metallurgical influence on the material to be cut and improving the quality of the cut surface.

In the above-mentioned plasma cutting method, the cooling gas is preferably a carbon dioxide gas or a mixed gas of a carbon dioxide gas and a reducing gas. By using such a cooling gas, it is possible to cool the cut portion in the material to be cut, and it is possible to prevent or reduce the oxidation of the material to be cut at the time of cutting.

In particular, since carbon dioxide is generally a liquefied gas, the material to be cut can be locally and efficiently cooled.

[0011] The plasma cutting torch according to the present invention comprises:
It is configured to include a plasma arc injection member for injecting a plasma arc toward a material to be cut, and a cooling gas injection member for injecting a cooling gas toward the material to be cut.

In the above-mentioned plasma cutting torch, a plasma arc can be jetted toward the material to be cut by the plasma arc jetting member, and a cooling gas can be jetted toward the material to be cut by the cooling gas jetting member. For this reason, cutting can be performed while cooling the cut portion of the material to be cut.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a plasma cutting method and a plasma cutting torch of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a state in which a plasma cutting method according to the present invention is performed, FIG. 2 is a plan view of a material to be cut including a plasma arc, a diagram illustrating a region to be cooled by a cooling gas, and FIG. FIG. 4 illustrates a configuration of a plasma cutting torch according to one embodiment, FIG. 4 illustrates a configuration of a plasma cutting torch according to a second embodiment, and FIG. 5 illustrates a configuration of a plasma cutting torch according to a third embodiment. FIG. 6 is a diagram illustrating a configuration of a plasma cutting torch according to a fourth embodiment, and FIG. 7 is a diagram illustrating a configuration of a plasma cutting torch according to a fifth embodiment.

A plasma cutting method according to the present invention will be described with reference to FIGS. In the drawing, while moving a cutting torch 1 while injecting a plasma arc 3 from a plasma cutting torch (hereinafter simply referred to as a “cutting torch”) 1 toward a material 2 to be cut, the thermal energy of the plasma arc 3 As a result, the portion to be jetted in the material to be cut 2 is melted,
In addition, the melt is removed from the base material by the injection energy of the plasma arc 3, and a continuous groove is formed in the workpiece 2 to perform cutting.

At the part (cutting part 4) of the material 2 to be ejected by the plasma arc 3, heat is conducted from the cutting part 4 as a starting point in the thickness direction and the plane direction of the material 2 to be cut. As a result, the temperature of the workpiece 2 increases. Therefore, the cooling gas 5 is moved toward the vicinity of the cut portion 4 in the material 2 to be cut.
The material 2 to be cut is cooled by injecting the gas, so that the range of the thermal influence on the material 2 to be cut can be reduced and the range can be limited to a narrow range.

In the plasma cutting method according to the present invention,
The type of plasma gas constituting the plasma arc 3 is not particularly limited. That is, the present invention is to limit the range of the thermal effect generated on the material 2 to be cut and reduce the thermal effect itself by cooling the vicinity of the cut portion 4 in the material 2 to be cut with the cooling gas 5. . Therefore, the material of the material to be cut 2 is not limited, and accordingly, the type of the plasma gas is not limited.

For example, when cutting a steel plate, an oxygen gas is used as a plasma gas, but the present invention can be applied to this cutting method. Further, when cutting non-ferrous metal, the present invention can be applied to a case where argon gas is used as a plasma gas or a case where hydrogen gas is mainly used and mixed with argon gas. Further, even when the present invention is applied to a cutting method using nitrogen gas or air as a plasma gas, it is possible to reduce and limit the range of thermal influence on the workpiece 2.

The cooling gas 5 can be used as long as it can efficiently cool the material 2 to be cut. However, it is not preferable to use a gas that burns the workpiece 2, for example, an oxidizing gas such as oxygen gas or air.

That is, when oxygen gas is used as the cooling gas 5, the oxygen gas may react with the melt of the base material at the cutting portion 5 and burn. 2 will be heated more. When an oxidizing gas such as air is used as the cooling gas 5, the oxidizing gas reacts with a melt of the base material at the cutting portion 5 or a high-temperature cut surface to form an oxide film on the surface. Becomes

In particular, it is not preferable to use an oxidizing gas when the material to be cut 2 is a material such as a stainless steel plate that forms a discoloration layer on the surface with oxidation. Therefore, in the present invention, a carbon dioxide gas or a mixed gas of a carbon dioxide gas and a reducing gas (for example, hydrogen gas) is used as the cooling gas 5.

When a carbon dioxide gas or a mixed gas of a carbon dioxide gas and a reducing gas is used as the cooling gas 5 and any one of these gases is injected near the cutting portion 4, the injected cooling gas adiabatically expands to a temperature. It is possible to cool the material to be cut 2 in a state where the pressure is lowered. Therefore, high cooling efficiency can be realized. In particular, carbon dioxide gas is generally supplied as a liquefied gas, and the temperature of the gas itself is low, and it is possible to anticipate a drop in gas temperature due to adiabatic expansion. Is possible.

The cooling gas 5 has a function of shielding the cutting portion 4 of the workpiece 2 from the atmosphere as a carbon dioxide gas atmosphere, thereby preventing or reducing the oxidation of the melt existing at the cutting portion 4. It is possible to do. In particular, when a mixed gas of carbon dioxide gas and reducing gas is used as the cooling gas 5, it is possible to prevent oxidation of the melt.

The cutting method according to the present invention is advantageous when the material to be cut 2 is relatively thick. That is, when cutting a thick plate, the cutting speed is reduced, so that the amount of heat input per unit length is larger than that of a thin plate. For this reason, when the material to be cut 2 is not cooled, the range of the thermal influence by the plasma arc 3 is increased on the surface side. However, by injecting the cooling gas 5 in the vicinity of the cutting portion 4 in the material to be cut 2, it becomes possible to cool the surface side of the material to be cut 2 and prevent the heat affected range from expanding. It is possible.

Further, the cutting method according to the present invention comprises
Is advantageous when the color changes due to oxidation as in a stainless steel plate. That is, the cooling gas 5 composed of carbon dioxide or a mixed gas of carbon dioxide and reducing gas is supplied to the cutting portion 4.
Is cut off from the atmosphere to prevent oxidation of the melt.

Next, the configuration of a cutting torch for performing the above cutting method will be described. FIG. 3 is a diagram illustrating the configuration of the cutting torch A according to the first embodiment. In the figure, the cutting torch A is configured so that a secondary airflow can be injected around the plasma gas 3.

That is, the cutting torch A is provided with an electrode 11 at the center, an insulating ring 12 is arranged by fitting the electrode 11, and an inner nozzle 13 is arranged on the outer periphery of the insulating ring 12. . Further, the inner nozzle 13 is fitted to the outer nozzle 14. Then, a plasma gas is supplied to a passage 15 formed between the electrode 11 and the internal nozzle 13, and a plasma arc 3 is formed as the electrode 11 is energized. In addition, a secondary airflow is supplied to a passage 16 formed between the inner nozzle 13 and the outer nozzle 14, and the secondary airflow is wrapped around the plasma arc 3 and injected. Therefore, the electrode 11 to the external nozzle 14
The plasma arc injection member is constituted by the portion constituted by.

A cooling gas nozzle 17 is arranged outside the external nozzle 14 so as to surround the external nozzle 14. A cooling gas passage 18 and a cooling gas injection port 19 are formed between the cooling gas nozzle 17 and the external nozzle 14. Cooling gas passage 18
Are formed independently of a passage 15 for supplying a plasma gas and a passage 16 for supplying a secondary gas flow, and are connected to a supply source of a cooling gas (not shown).

Therefore, when the cooling gas is supplied to the cooling gas passage 18, the gas is injected from the cooling gas injection port 19 toward the material 2 to be cut, so that the area around the cut portion 4 can be cooled.

In the cutting torch A according to the present embodiment, it is possible to cool over the entire circumference centering on the cutting portion 4 of the workpiece 2. Therefore, the cutting torch A has no directionality, and is advantageous when the cutting torch is two-dimensionally moved and cut like a die cutting device.

Next, the configuration of the cutting torch B according to the second embodiment will be described with reference to FIG. The same portions and portions having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted (hereinafter, the same applies to the third embodiment and thereafter).

The cutting torch B is provided with a chip 20 having a plurality of cooling gas jets 19 formed between an external nozzle 14 and a cooling gas nozzle 17. Even with the cutting torch B configured as described above, the cooling gas can be injected from the cooling gas injection port 19, and the cutting portion 4 in the workpiece 2 is cut.
And cooling over the entire circumference. Therefore, the cutting torch B also has no directionality, which is advantageous when the cutting torch is moved two-dimensionally and cut like a die cutting device.

FIG. 5 is a view for explaining the configuration of the cutting torch C according to the third embodiment. In the cutting torch C, a cooling gas nozzle 21 formed in a ring shape and having a plurality of cooling gas injection ports 19 is arranged outside the external nozzle 14. The cooling gas nozzle 21 is configured to be detachable from the torch main body, and can be attached or detached as needed.

The cutting torch C according to the present embodiment is different from the above-described cutting torch B in the mechanism for injecting the cooling gas, but has substantially the same function. It is possible to cool over the entire circumference centering on 4. Therefore, the cutting torch C also has no directionality, which is advantageous when the cutting torch is two-dimensionally moved and cut like a die cutting device.

FIG. 6 is a view for explaining the structure of a cutting torch D according to the fourth embodiment. In the cutting torch D, a cooling gas nozzle 22 is disposed outside the external nozzle 14, and the cooling gas nozzle 22 forms an oval cooling gas injection port 19. One center of the ellipse shares the center of the electrode 11, and the other center has a position separated from the center by a predetermined distance.

In the cutting torch D, it is possible to cool the periphery of the cutting portion 4 in the material to be cut 2 and to more effectively cool the longitudinal direction of the cooling gas injection port 19. is there. Therefore, it is advantageous, for example, in a case where the kerfs formed in the workpiece 2 are intensively cooled as the cutting progresses. However, since the cooling gas injection port 19 has directionality, when the cutting torch D is mounted on the die cutting device, it is necessary to turn the cutting torch D in accordance with a change in the cutting direction as the cutting progresses. is there.

However, even with the cutting torch D configured as described above, the cooling gas can be injected from the cooling gas injection port 19 to cool the cut portion 4 in the workpiece 2.

FIG. 7 is a view for explaining the configuration of the cutting torch E according to the fifth embodiment. In the cutting torch E, a cooling gas nozzle 23 is arranged along one side of the external nozzle 14. The cooling gas nozzle 23 is constituted by a pipe, and the cooling gas injection port 19 is formed by an opening of the pipe.

In this cutting torch E, the vicinity of the cutting portion 4 in the material to be cut 2 cannot be cooled over the entire circumference. It is possible to cool the moving direction or the inside of the cut groove formed in the workpiece 2. Therefore, although the direction for cutting is generated, it is possible to effectively use the cooling gas.

[0039]

As described above in detail, in the plasma cutting method according to the present invention, it is possible to cool the vicinity of the portion where the base material is melted by the injection of the plasma arc.
For this reason, the range of the thermal influence on the material to be cut due to the plasma cutting can be reduced, and the cutting quality can be improved.

In particular, when a carbon dioxide gas or a mixed gas of a carbon dioxide gas and a reducing gas is used as the cooling gas, the quality of the cut surface is improved by preventing oxidation of the cut portion of the material to be cut. Can be done.

In the plasma cutting torch according to the present invention, the above-described plasma cutting direction can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state in which a plasma cutting method according to the present invention is performed.

FIG. 2 is a plan view of a material to be cut including a plasma arc, illustrating a region to be cooled by a cooling gas.

FIG. 3 is a diagram illustrating a configuration of a plasma cutting torch according to the first embodiment.

FIG. 4 is a diagram illustrating a configuration of a plasma cutting torch according to a second embodiment.

FIG. 5 is a diagram illustrating a configuration of a plasma cutting torch according to a third embodiment.

FIG. 6 is a diagram illustrating a configuration of a plasma cutting torch according to a fourth embodiment.

FIG. 7 is a diagram illustrating a configuration of a plasma cutting torch according to a fifth embodiment.

[Explanation of symbols]

 A to E Cutting torch 1 Cutting torch 2 Material to be cut 3 Plasma arc 4 Cutting site 5 Cooling gas 11 Electrode 12 Insulating ring 13 Internal nozzle 14 External nozzle 15, 16 Passage 17, 21, 22, 23 Cooling gas nozzle 18 Cooling gas passage 19 Cooling gas injection port

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B23K 9/16 B23K 9/16 J

Claims (3)

[Claims] In a plasma cutting method for cutting a material to be cut by injecting a plasma arc toward the material to be cut,
A plasma cutting method characterized by injecting a cooling gas near a portion of a workpiece to which a plasma arc is injected to cool the workpiece. 2. The plasma cutting method according to claim 1, wherein said cooling gas comprises carbon dioxide or a mixed gas of carbon dioxide and reducing gas. 3. A plasma cutting torch, comprising: a plasma arc injection member for injecting a plasma arc toward a material to be cut; and a cooling gas injection member for injecting a cooling gas toward the material to be cut.