JP5797515B2 - Plasma cutting method - Google Patents

Description

  The present invention relates to a plasma cutting method capable of improving the durability of an electrode.

  Conventionally, when a material to be cut having electrical conductivity is cut using a transfer type plasma torch, a gas to be converted into plasma is supplied around the tip surface of the electrode attached to the plasma torch and between the electrode and the nozzle. Energize to form a pilot arc and blow out from the nozzle. When the blown pilot arc comes in contact with the material to be cut, energize the electrode to form the main arc and simultaneously stop energization between the electrode and the nozzle. Then, the pilot arc is stopped, and then the material to be cut is melted by the main arc and the plasma torch is moved while the melt is removed from the base material.

  In particular, when the material to be cut is a steel plate, oxygen gas is generally used as the plasma gas. For this reason, the electrode is used under extremely severe conditions such as in a highly oxidizing atmosphere and at an extremely high temperature, and there is a problem that the life is extremely shortened. In order to solve such a problem, many techniques aimed at extending the life of the electrode have been proposed.

  For example, in the invention described in Patent Document 1, air is supplied to the working gas passage for preflow and postflow, and a mixed gas of oxygen and air is supplied to the main flow for cutting. Yes. In this technique, at the time of pilot arc ignition, the use of a working gas having a high nitrogen concentration reduces the consumption of electrodes and nozzles. In addition, during cutting, since a mixed gas containing oxygen and nitrogen is used as a working gas, consumption of the electrodes is suppressed.

  In the invention described in Patent Document 1, electrode consumption can be suppressed. However, the actual situation is that further improvement in durability of the electrode is required. For this reason, the applicant of the present invention realizes the adoption of a thicker electrode material by increasing the diameter of the tip surface of the electrode, and the plasma gas can be supplied to a portion closer to the electrode material on the tip surface. And a plasma torch using this electrode has been proposed (see Patent Documents 2 and 3).

Japanese Patent No. 3666789 Japanese Patent No. 4609963 Japanese Patent No. 4648568

  As described above, in the invention described in Patent Document 1, although electrode consumption can be suppressed, further improvement in electrode durability is required.

  In addition, the inventions described in Patent Documents 2 and 3 relate to the single structures of the electrode and the plasma torch, respectively, and there is a problem that a rational plasma cutting method using these electrodes and the plasma torch has not been developed. There is.

  An object of the present invention is to provide a plasma cutting method capable of improving the durability of an electrode without deteriorating cutting performance on the premise of the electrode and plasma torch described in Patent Documents 2 and 3. is there.

In order to solve the above-described problems, a plasma cutting method according to the present invention includes an electrode having an electrode gas passage that penetrates the body and has one end opened to the tip surface, and a nozzle that forms a pilot arc between the electrodes. An electrode gas supply path for supplying an electrode gas to the electrode gas passage of the electrode, and a plasma for supplying a plasma gas to a space formed between the electrode and the nozzle, the electrode gas supply path being configured independently of the electrode gas supply path A plasma torch having a gas supply path, and supplying an electrode gas made of air, nitrogen gas or argon gas from the electrode gas supply path to the electrode gas path of the electrode, in synchronization with the formation of the pilot arc and the main arc A material to be cut by a main arc made of a mixed gas of the plasma gas and electrode gas by supplying a plasma gas made of oxygen gas from a plasma gas supply path A plasma cutting method for cutting, wherein the electrode gas supply channel of the plasma torch, the electrode gas supply system having an electrode gas supply device and the flow regulator is connected to a plasma gas supply path of the plasma torch, the plasma A plasma gas supply system having a gas supply device and a flow rate regulator is connected, and before the plasma arc is supplied from the plasma gas supply path to the plasma chamber to form a pilot arc, the supply of the plasma gas is cut off before the main arc is supplied. The electrode gas is supplied from the electrode gas supply passage to the electrode gas passage of the electrode until after the interruption.

  In the plasma cutting method, the electrode gas when cutting the material to be cut is preferably in the range of 5% to 25% with respect to the total amount of the electrode gas and the plasma gas.

  In the plasma cutting method according to the present invention, an electrode in which an electrode gas passage that passes through the body portion and opens at the front end surface is used, and one of two independent gas supply passages configured in the plasma torch is connected to the electrode gas. While connecting with a channel | path, the other is connected to the plasma gas supply path. For this reason, a gas (electrode gas) selected from air, nitrogen gas, and argon gas can be supplied to the electrode gas passage, and oxygen gas can be supplied to the plasma gas supply passage. Therefore, the electrode gas concentration at the central portion on the tip surface of the electrode is increased, and deterioration due to oxidation of the electrode can be reduced to improve durability.

  In particular, since the electrode gas when cutting the material to be cut (when forming the main arc) is in the range of 5% to 25% with respect to the total amount of the electrode gas and the plasma gas, the cutting speed is reduced. It becomes possible to prevent the cutting surface from becoming rough, and the cutting performance is not deteriorated.

It is sectional drawing which shows the structure of the plasma torch used for the plasma cutting method which concerns on this invention. It is sectional drawing of the direction different from FIG. It is a block diagram which shows the gas path | route supplied to a plasma torch. It is a figure explaining the structure of an electrode. It is a figure explaining the timing flow at the time of operating a plasma torch.

  Hereinafter, the plasma cutting method according to the present invention will be described.

  First, the configuration of a plasma torch and electrodes used when carrying out the plasma cutting method of the present invention will be described. 1 and 2, the plasma torch B is equipped with an electrode A as shown in FIG. The electrode A is converted into a plasma from the gas supplied to the front end surface 4 side, sprayed from the nozzle 11a of the plasma torch B, and cooled by the cooling water supplied to the hole 7 on the back side. An electrode gas passage 6 having an end disposed at a predetermined position on the outer peripheral surface is provided.

  The electrode A has an attachment portion 1 for attachment to a conductive electrode base 12 connected to a conductive electrode base 9 provided in the main body of the plasma torch B, and a body portion 2. A screw portion 1a that is screwed into a screw portion of the electrode base 12 is formed inside the attachment portion 1, and a linear portion 1b that cuts a hexagonal material and hangs a spanner and a curved surface portion 1c formed by cutting are formed at the outer peripheral portion. Has been.

  A ring-shaped groove 3 is formed on the entire body 2, and a guide part 2 a having a preset outer diameter is formed continuously with the groove 3. Further, a stepped portion 2b and a tapered portion 2c are formed on the tip side of the guide portion 2a. A tip surface 4 is formed on the tip side of the tapered portion 2c, and an electrode material 5 made of hafnium, tungsten, or the like is embedded in the center of the tip surface 4.

  One end of the distal end surface 4 is disposed on the distal end surface 4 and is open, and the other end is a predetermined position on the outer peripheral surface of the body portion 2 (in this embodiment, in the groove 3 formed on the outer periphery of the body portion 2. An electrode gas passage 6 that is arranged and opened on the surface on the guide portion 2a side is formed.

  Further, a hole 7 through which cooling water flows is formed inside the electrode A, and a protrusion for increasing heat exchange efficiency by increasing the surface area on the back surface of the tip surface 4 which is the bottom surface of the hole 7. 8 is formed.

  In this embodiment, by providing such an electrode gas passage 6, an electrode gas selected from air, nitrogen gas, and argon gas can be supplied to the vicinity of the electrode material 5. For this reason, regardless of the value of the outer diameter of the tip surface 4 of the electrode A, it is possible to supply the electrode gas from a position provided in the vicinity of the electrode material 5 to reduce the apparent electrode tip diameter.

  The number of the electrode gas passages 6 is not particularly limited, but in order to ensure uniform gas supply to the electrode A, a plurality of electrode gas passages 6 are preferable, and the plurality of electrode gas passages 6 are arranged at substantially equal intervals. It is preferable.

  For this reason, in this embodiment, three electrode gas passages 6 are formed in the electrode A and at an angular interval of 120 degrees from each other. By forming the electrode gas passage 6 in this way, the electrode gas can be supplied substantially uniformly around the electrode material 5 in the electrode A.

  Further, the electrode gas passage 6 is formed to be inclined toward the center of the electrode A from the groove 3 formed in the body portion 2 of the electrode A to the distal end surface 4. In this way, by inclining the electrode gas passage 6, the gas supplied from the electrode gas passage 6 can be converged to a portion of the electrode A that is not greatly separated from the electrode material 5.

  The electrode gas passage 6 can be formed by a hole as shown in the present embodiment, and can also be formed by a slit. When the electrode gas passage 6 is formed by a hole, the pitch circle diameter φd (see FIG. 4A), which is the diameter of the hole, is preferably set in a range from 6 mm to the outer diameter of the tip surface 4.

  In this way, by setting the opening position of the tip surface 4 of the electrode gas passage 6, it is possible to supply the electrode gas supplied from the electrode gas passage 6 to the vicinity of the electrode material 5 constituting the electrode A. Become. For this reason, when the main arc is formed, the vicinity of the electrode material 5 is maintained in an inert atmosphere, and the pressure around the electrode material 5 is reduced to promote evaporation of hafnium, tungsten, and the like. Absent.

  The electrode A is attached by fastening the screw portion 1a of the attachment portion 1 to the screw portion 12a of the electrode base 12 connected by being inserted and fitted into the electrode base 9 provided in the main body of the plasma torch B. A cooling pipe 13 for supplying cooling water is provided inside the electrode base 9 and the electrode base 12.

  When the electrode A is attached to the electrode base 12, the cooling pipe 13 is inserted into the hole 7 formed inside the electrode A to form a cooling water flow passage 14 inside and outside the cooling pipe 13. However, some types of plasma torch B can be attached by simply inserting the electrode A into the electrode base 12.

  The guide portion 2 a formed on the body portion 2 of the electrode A has an outer diameter slightly smaller than the inner diameter of the centering stone 15. For this reason, after attaching the electrode A to the electrode base 12, the centering stone 15, the inner nozzle member 16, and the inner cap 17 are sequentially attached to the electrode A, and the conductive nozzle base is attached to the main body. When the electrode base 12 in a free state is inclined with respect to the axis 18 of the plasma torch B by screwing with the screw portion 24a of the electrode 24, the inclination is corrected and the electrode material 5 of the electrode A is corrected. Can substantially coincide with the axis 18.

  The plasma gas is supplied from the periphery of the electrode A to the distal end face 4 side of the electrode A through the plasma gas supply path 23 shown in FIG. The electrode gas is supplied to the electrode gas passage 6 provided in the electrode A through the electrode gas supply passage 19.

  That is, in this embodiment, the plasma gas supply path 23 to which the plasma gas is supplied and the electrode gas supply path 19 to which the electrode gas is supplied are provided independently.

  As shown in FIG. 1, the plasma gas supply path 23 is formed on the outer periphery of the centering stone 15 through passages formed in the electrode base 9, a resin insulating block 25 that forms a water channel (not shown), and a nozzle base 24. A hole 26 a formed in the centering stone 15 and between the outer peripheral surface of the electrode A and the inner peripheral surface of the inner nozzle member 16. And communicated with the nozzle 11a.

  A plurality of holes 15a are formed in a predetermined portion on the front end side of the centering stone 15, and plasma gas can be supplied from the passage 26 to the step 2b side of the body 2 of the electrode A through the holes 15a. .

  In the present embodiment, the hole 15 a formed in the centering stone 15 is formed so as to be inclined at a predetermined angle in which the axial direction does not intersect the axis 18, and the plasma supplied via the plasma gas supply path 23 is formed. The gas can be supplied in a swirled state into the plasma chamber 20 formed between the outer peripheral surface of the electrode A and the inner peripheral surface of the inner nozzle member 16.

  Further, the electrode gas supply path 19 passes through a passage formed in another part of the electrode pedestal 9, and the outer peripheral surface of the electrode base 12 and the inner peripheral surface of the insulating flameproof pipe 27 made of ceramic or the like. Communicating with a passage 28 formed therebetween, and further communicating with a passage 29 formed between the outer peripheral surface of the mounting portion 1 of the electrode A and the inner peripheral surface of the centering stone 15, and further formed inside the electrode A. The electrode gas passage 6 communicates with the plasma chamber 20 and further with the nozzle 11a.

  The plasma gas supply path 23 and the electrode gas supply path 19 configured as described above are configured as supply paths independent of each other.

  The plasma chamber 20 is formed by the tip surface 4 of the electrode A and the inner peripheral surface of the inner nozzle member 16. When the conductive inner nozzle member 16 is attached to the insulating centering stone 15, It is configured such that a pilot arc can be formed between the electrode A and the electrode A by contacting the nozzle base 24 with a conductive nozzle base 24 and energizing the nozzle base 24 from a main body through an energization circuit (not shown). ing.

  And when forming a pilot arc, it was preset between the electrode A and the inner nozzle member 16, and when forming a main arc, it was preset between the electrode A and a workpiece (not shown). A voltage is applied and discharged between the inner nozzle member 16 and the workpiece.

  When the electrode A is attached to the electrode base 12, the tip of the cooling pipe 13 is inserted into the hole 7 formed in the electrode A, and the cooling water supplied through the cooling pipe 13 passes through the flow passage 14. Then, after colliding with the protrusion 8 formed on the back surface side of the electrode material 5 disposed on the electrode A, the electrode A is cooled by coming into contact with the inner surface of the electrode A. Thereafter, the cooling water passes through the passage 21, cools the inner nozzle member 16, and is discharged to the outside.

  A centering stone 15 is attached to the electrode A attached to the electrode table 12. At this time, the outer periphery of the guide portion 2 a formed on the electrode A is guided in contact with the inner surface of the centering stone 15. In this state, the centering stone 15 is merely in contact with the guide portion 2a of the electrode A and does not regulate the electrode A at all. Then, an inner cap 17 is attached to the inner nozzle member 16, and the inner cap 17 is screwed into a screw portion 24a of a nozzle base 24 fixed to the main body so that the electrode A is substantially aligned with the axis 18. Is possible.

  Further, when the outer cap 31 is attached to the outer nozzle member 30 and the outer cap 31 is screwed into the screw portion 33a of the outer connecting cap 33 fixed to the torch guard 32 attached to the main body, the outer nozzle member 30 A secondary air flow chamber 22 is formed between the inner nozzle member 16 and the inner nozzle member 16, and a secondary gas supplied to the secondary air flow chamber 22 is sheathed around the main arc that injects from the nozzle 11a of the inner nozzle member 16. It is possible to inject.

  As shown in FIG. 2, the secondary gas supplied to the secondary air flow chamber 22 is a partition mounted on the outer nozzle member 30 through a passage 34 and a passage formed in each of the electrode base 9 and the insulating block 25. It communicates with a passage 36 formed between the inner peripheral surface of the member 35 and the outer peripheral surface of the inner cap 17, communicates with the secondary air flow chamber 22 through a hole 30 a formed in the outer nozzle member 30, and further, the outer nozzle It communicates with the nozzle 11b of the member 30.

  Further, as shown in FIG. 2, the passage 37 is formed between the outer peripheral surface of the partition member 35 and the inner peripheral surface of the outer cap 31 through the passages formed in the electrode base 9 and the insulating block 25. The tertiary gas can be injected in a sheath shape around the secondary gas through the hole 30 b formed in the outer nozzle member 30 in communication with the passage 38.

  Next, an electrode gas supply system that supplies an electrode gas selected from air, nitrogen gas, and argon gas to the electrode gas supply path 19 of the plasma torch B configured as described above, and a plasma gas to the plasma gas supply path 23 as plasma gas. The structure of an oxygen gas supply system for supplying the oxygen gas will be described with reference to FIG. In this embodiment, air is selected as the electrode gas supplied to the electrode gas supply path 19.

  That is, the electrode gas supply system is an air compressor or the like, an electrode gas supply device 41a selected from a nitrogen gas cylinder or an argon gas cylinder, a pressure switch 42a that detects when a preset pressure is applied, and generates an electric signal, an electrode gas Electromagnetic valve 43a that shuts off and opens the supply system, pressure stabilizer 44a for air including an accumulator, and a flow rate regulator that stabilizes the flow rate by adjusting the pressure with an electric signal generated by detecting the flow rate on the output side The electropneumatic regulator 45a is connected to the electrode gas supply path 19 formed in the plasma torch B through these.

  The oxygen gas supply system also supplies oxygen gas to the plasma gas supply path 23, oxygen gas to the passage 34 for supplying oxygen gas as a secondary gas, and passage 37 for supplying oxygen gas as tertiary gas. It is comprised so that supply of the oxygen gas with respect to can be performed.

  For this reason, the oxygen gas supply system includes an oxygen gas supply device 41b composed of factory piping, an oxygen cylinder, and the like, a pressure switch 42b that detects when a preset pressure is applied, and generates an electrical signal, and each passage 23, 34, 37. The electromagnetic valves 43b to 43d provided corresponding to the pressure regulators, the oxygen pressure stabilizers 44b to 44d including the accumulator, and the flow rate is stabilized by adjusting the pressure by the electric signal generated by detecting the flow rate on the output side. Electropneumatic regulators 45b to 45d serving as flow rate regulators are connected to the plasma gas supply passage 23, the secondary gas passage 34, and the tertiary gas passage 37, which are configured in the plasma torch B, via these. ing.

  In particular, an electropneumatic regulator 45c is connected to the downstream side of the pressure stabilizer 44c for oxygen gas corresponding to the secondary gas passage 34, and a check valve 46 is connected to the downstream side of the electropneumatic regulator 45c. It is connected.

  In the electrode gas supply system and the oxygen gas supply system configured as described above, supply to the electrode gas supply path 19 is performed by changing the supply pressure using the pressure stabilizers 44a and 44b and the electropneumatic regulators 45a and 45b. It is possible to change the flow rate of air (electrode gas) and / or the flow rate of plasma gas (oxygen gas) supplied to the plasma gas supply path 23.

  Next, a procedure for carrying out the plasma cutting method according to the present invention using the plasma torch B to which the electrode A constructed as described above is attached will be described with reference to FIG.

  In the plasma cutting method according to the present invention, a gas selected from air, nitrogen gas, and argon gas is used as the electrode gas. Which of these gases is selected is not limited, and the durability of the electrode can be improved regardless of which gas is selected. However, according to the knowledge of the present inventors, when hafnium is used as the electrode material 5, it is preferable to select air, and when tungsten is used as the electrode material 5, it is preferable to select nitrogen gas or argon gas. .

  For example, in the electrode A using hafnium as the electrode material 5, the periphery of the electrode material 5 is preferably a slightly oxidizing atmosphere. For this reason, when the material to be cut is cut by the electrode A, by supplying air from the electrode gas passage 6 to the tip surface 4 side, the periphery of the electrode material 5 becomes a slight oxidizing atmosphere, and hafnium consumption is suppressed. Thus, it is possible to ensure the quality of the cut surface in the material to be cut.

  In addition, in the electrode A using tungsten as the electrode material 5, the periphery of the electrode material 5 is preferably a non-oxidizing atmosphere. For this reason, when the material to be cut is cut by the electrode A, the periphery of the electrode material 5 is made non-oxidizing atmosphere by supplying nitrogen gas or argon gas from the electrode gas passage 6 to the tip surface 4 side. It becomes possible. And by making the surroundings of the electrode material 5 into a non-oxidizing atmosphere, it is possible to suppress the consumption of tungsten and to ensure the quality of the cut surface in the material to be cut.

  In this embodiment, hafnium is used as the electrode material 5 of the electrode A, and air is selected as the electrode gas. For this reason, an air compressor is used as the electrode gas supply device 41a.

  When supplying the electrode gas to the electrode gas supply path 19 of the plasma torch B, the flow rate of the electrode gas is set by the electropneumatic regulator 45a constituting the electrode gas supply system. Further, when the plasma gas is supplied to the plasma gas supply path 23, the flow rate of the electrode gas is set by the electropneumatic regulator 45b constituting the plasma gas supply system. Then, the electrode gas and the plasma gas can be supplied to the plasma torch B by appropriately driving the electromagnetic valves 43a and 43b.

  In the present invention, the electrode gas is supplied to the electrode gas supply path 19 of the plasma torch B before the pilot arc is formed, and is ejected to the plasma chamber 20 through the electrode gas path 6 of the electrode A to surround the electrode material 5. An inert atmosphere is formed (preflow). In addition, the electrode gas is supplied while the main arc is formed, and the inert atmosphere around the electrode material 5 is continued, and the main arc is formed by the gas in which the electrode gas and the plasma gas are mixed. Furthermore, the electrode gas is supplied even after the main arc is interrupted, and continues the inert atmosphere around the electrode material 5 and contributes to cooling of the electrode material 5 (afterflow).

  Specifically, as shown in FIG. 5, prior to the formation of the pilot arc, the electromagnetic valve 43a constituting the electrode gas supply system is opened to perform preflow of the electrode gas. By this preflow, the plasma chamber 20 is filled with air, and the periphery of the electrode material 5 embedded in the tip surface 4 of the electrode A becomes an inert atmosphere.

  When the electromagnetic valve 43b constituting the oxygen gas supply system is opened while the supply of the electrode gas to the plasma torch B is continued, the oxygen gas supplied from the oxygen gas supply device 41b and whose flow rate is set by the electropneumatic regulator 45b is obtained. , Supplied to the plasma gas supply path 23. At the same time, electricity is applied between the electrode A and the inner nozzle member 16 and between the electrode A and the material to be cut, thereby forming a pilot arc.

  When the pilot arc is blown out of the nozzle 11a and comes into contact with the workpiece, the pilot arc is switched to the main arc, and at the same time, the energization between the electrode A and the inner nozzle member 16 is cut off and the pilot arc is eliminated.

  When the main arc is formed, the inside of the plasma chamber 20 is a mixture of plasma gas composed of oxygen gas and electrode gas composed of air. However, since the electrode gas passage 6 is open to the distal end surface 4 of the electrode A, an inert atmosphere continues around the electrode material 5 due to the electrode gas continuously supplied from the electrode gas passage 6.

  When the target plasma cutting for the material to be cut is completed, the energization between the electrode A and the material to be cut is cut off, and simultaneously the supply of oxygen gas is stopped. However, the supply of the electrode gas to the plasma torch B is continued and the afterflow is continued. By the after-flow of the electrode gas, the inert atmosphere around the electrode material 5 is continued, and the cooling of the electrode A is promoted.

  As described above, in the present invention, an electrode gas passage is formed in the electrode A by penetrating the body 2 of the electrode A, and air, nitrogen gas, or argon gas is formed from the electrode gas passage 6 to the tip surface 4 side. By supplying the gas selected from the above, it becomes possible to cool the body portion of the electrode A by the electrode gas from the inside, so that the durability of the electrode A can be improved.

  In addition, since the electrode gas passage 6 is opened in the tip end face 4 of the electrode A, it is possible to prevent an inert atmosphere due to the electrode gas from being formed around the electrode material 5 to become a highly oxidized atmosphere. The durability of the material 5 can be improved, and the durability of the electrode A can be improved accordingly.

  The present inventor uses an electrode using hafnium as an electrode material, sets the output of the plasma torch to 400 ampere (A), sets the total gas flow rate when forming the main arc to 40 L / min, The ratio of the electrode gas is changed in the range of 0% to 30%, the main arc is formed for 1 minute, the material to be cut is cut, and then it is stopped for 30 seconds. Durability experiments were conducted to compare quality.

  When the main arc was formed with only oxygen gas without supplying any electrode gas (0%), the durability was 181 times, and the cutting performance (cutting speed) was almost satisfactory.

  When 5% of the electrode gas was supplied and 95% of the oxygen gas was supplied to the total gas flow rate, the durability was improved to 193 times, and the cutting performance was almost satisfactory.

  When 10% of the electrode gas was supplied and 90% of the oxygen gas was supplied to the total gas flow rate, the durability was greatly improved to 246 times, and the cutting performance was sufficiently satisfactory.

  When the electrode gas was supplied 15% and the oxygen gas was 85% with respect to the total gas flow rate, the durability was greatly improved to 262 times, and the cutting performance was sufficiently satisfactory.

  When the electrode gas was supplied at 20% with respect to the total gas flow rate and the oxygen gas was set at 80%, the durability was greatly improved to 231 times, and the cutting performance could be substantially satisfied.

  When the electrode gas was supplied at 25% and the oxygen gas was 75% with respect to the total gas flow rate, the durability was 187 times, and the cutting performance was almost satisfactory.

  When the electrode gas was supplied 30% and the oxygen gas was 70% with respect to the total gas flow rate, the durability was reduced to 127 times, and the cutting performance was not satisfactory.

  As a result of the above experiment, the flow rate of the electrode gas is 5% to 25% with respect to the total gas flow rate (the sum of the plasma gas flow rate and the electrode gas flow rate) for forming the main arc when cutting the workpiece. It is preferably in the range, and more preferably in the range of 10% to 15%.

  When the flow rate of the electrode gas is increased, the cause of the decrease in durability is that the flow velocity of the electrode gas at the tip surface 4 of the electrode A increases, and as a result, the electrode material 5 is buried due to the suction force. This is because the electrode material 5 is sucked out.

  The plasma cutting method according to the present invention is advantageous when used for the plasma torch and the electrode described in Patent Documents 2 and 3.

A electrode B plasma torch 1 mounting part 1a screw part 1b straight line part 1c curved surface part 2 trunk part 2a guide part 2b step part 2c taper part 3 groove 4 tip face 5 electrode material 6 electrode gas passage 7 hole 8 protrusion 9 electrode base 11a, 11b Nozzle 12 Electrode stand 13 Cooling pipe 14 Flow path 15 Centering stone 16 Inner nozzle member 17 Inner cap 19 Electrode gas supply path 20 Plasma chamber 21, 26, 28, 29
Passage 22 Secondary air flow chamber 23 Plasma gas supply path 24 Nozzle base 30 Outer nozzle member 31 Outer cap 41a Electrode gas supply device 41b Oxygen supply device 42a, 42 Pressure switch 43a-43d Electromagnetic valve 44a-44d Pressure stabilizer 45a-45d Electric Empty regulator 46 Check valve

Claims (2)

An electrode having an electrode gas passage penetrating through the body and having one end opened to the tip surface;
A nozzle that forms a pilot arc with the electrode;
An electrode gas supply passage for supplying an electrode gas to the electrode gas passage of the electrode;
Using a plasma torch having a plasma gas supply path configured to be independent of the electrode gas supply path and supplying a plasma gas to a space formed between the electrode and the nozzle,
An electrode gas consisting of air, nitrogen gas or argon gas is supplied from the electrode gas supply path to the electrode gas path of the electrode, and a plasma gas consisting of oxygen gas is supplied from the plasma gas supply path in synchronization with the formation of the pilot arc and the main arc. A plasma cutting method of cutting a material to be cut by a main arc composed of a mixed gas of the plasma gas and an electrode gas,
The electrode gas supply path of the plasma torch is connected to an electrode gas supply system having an electrode gas supply device and a flow rate regulator,
A plasma gas supply system having a plasma gas supply device and a flow rate regulator is connected to the plasma gas supply path of the plasma torch,
From before the plasma gas is supplied from the plasma gas supply path to the plasma chamber to form the pilot arc, the supply of the plasma gas is interrupted and the main arc is interrupted until the electrode gas passage of the electrode from the electrode gas supply path. A plasma cutting method comprising supplying an electrode gas. 2. The plasma cutting method according to claim 1, wherein the electrode gas in cutting the workpiece is in a range of 5% to 25% with respect to a total amount of the electrode gas and the plasma gas.

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