JP3984584B2 - Plasma torch - Google Patents

Description

  The present invention relates to a plasma torch that is equipped with a nozzle for injecting a plasma arc toward a workpiece to cut and melt the workpiece and to supply and drain cooling water to the nozzle. In order to realize effective cooling, it is possible to mount the nozzle without special positioning even if it is configured to restrict the flow direction at least at the inlet of the cooling water. It concerns plasma torches.

  For example, when a material to be cut such as a steel plate or a stainless steel plate is cut, a plasma cutting method capable of improving the cutting speed as compared with a gas cutting method is often employed. In this plasma cutting method, a plasma arc is jetted toward a material to be cut, the base material is melted by the heat of the plasma arc, and the melt is removed by the plasma arc jetting energy.

  As an example of performing a typical plasma cutting method, a configuration of a plasma torch described in Patent Document 1 will be briefly described. An electrode is attached to the center of the plasma torch, and a nozzle (also referred to as a tip) that is configured to be detachable from the plasma torch is provided with a jet outlet for injecting a plasma arc at the center facing the electrode. Has been. The nozzle is fixed by fastening a cap to the plasma torch, and a passage for circulating cooling water is formed in an annular shape between the outer peripheral surface of the nozzle and the inner peripheral surface of the cap.

  The plasma torch is formed with cooling water channels (supply channels and drainage channels) for cooling the electrodes, and these supply channels and drainage channels are passages formed between the nozzle and the cap and through which the cooling water flows. It is open. The nozzle attached to the plasma torch is arranged such that the outer peripheral surface is exposed to the cooling water passage.

  In the above configuration, the cooling water supplied to the plasma torch contacts the back side of the electrode to cool the electrode, and then is supplied to the passage formed between the cap and the nozzle and passes through this passage. In the process, the nozzle is cooled and then drained outside the plasma torch. Therefore, the electrode and the nozzle are cooled by the cooling water, thereby preventing excessive heating due to the heat of the plasma arc.

  In the plasma torch configured as described above, the plasma arc formed by energization between the electrode and the material to be cut is cooled and throttled when passing through the nozzle outlet and directed toward the material to be cut. Can be cut by melting the material to be cut and excluding the melt.

Japanese Patent Publication No. 3-27309

  In the plasma torch described in Patent Document 1 as described above, when a nozzle is attached to the plasma torch using a cap, an annular shape constituted by a front end surface on the plasma torch side, an outer peripheral surface of the nozzle, and an inner peripheral surface of the cap. The space is configured as a cooling water passage, and a cooling water supply passage and a drain passage provided in the plasma torch are opened in the passage. The passage generally has a smaller cross-sectional area as it approaches the tip of the cap from the portion closest to the plasma torch. Therefore, the cooling water supplied from the plasma torch side is discharged from the supply passage to the drain passage. There is a problem that the coolant is circulated at the shortest distance to the nozzle and the cooling water flow is stagnant at the tip of the nozzle (near the injection hole), resulting in insufficient cooling.

  In order to solve the above problem, if the flow of the cooling water in the passage is restricted so as to reach the tip of the nozzle, the nozzle is attached to the plasma torch when the nozzle is mounted on the plasma torch. Therefore, there arises a problem that the nozzle needs to be positioned and the nozzle attaching / detaching operation becomes complicated. For example, a nozzle and a cap are integrated to form a hollow portion, two pipes are attached to the hollow portion to form an independent water channel, and one pipe is inserted into a supply port provided in the plasma torch. If the other pipe is connected to the drain outlet and connected, the cooling water flow can be regulated to cool down to the tip of the nozzle. The operation of inserting into the drainage port is required, and there arises a problem that the attaching operation and particularly the removing operation are not easy.

  It is an object of the present invention to require positioning work even for a nozzle in which the direction of cooling water supply and drainage is limited by being configured to be able to effectively cool down to the plasma arc injection hole. It is an object of the present invention to provide a plasma torch that can be easily attached without being attached, and can be attached even with a normal nozzle.

In order to solve the above problems, the plasma torch according to the present invention has an injection hole for injecting a plasma arc at the center and an annular passage for cooling water and a plurality of independent water passages communicating with the annular passage. A plasma torch having a water channel for circulating cooling water for cooling the nozzle by mounting a nozzle, a supply port connected to the water channel and supplying cooling water to the nozzle, and connected to the water channel and passed through the nozzle A drain port for draining the cooling water, and the supply port and / or the drain port is connected to the water channel and is configured by a groove extending in a plane crossing the axis of the water channel while, independent intervals on the circumference of the end portion and the end portion of the supply port or discharge port of the interval or one of the grooves on the circumference of the end portion of the groove to each other of the both are formed in the nozzle Circumference of waterway Or an independent water channel and a supply port formed in the nozzle when the nozzle is mounted, and formed in the nozzle. Any one of the independent water channels and the drain outlet can communicate with each other.

  In the plasma torch, the supply port and / or the drain port formed in the plasma torch is formed as a groove extending in a plane perpendicular to the axis of the water channel. The open area on the mounting surface can be increased. For this reason, even if the supply port and the drain port are opened in the space constituted by the nozzle and the cap as in the plasma torch described in Patent Document 1, it can be used without any trouble.

  In particular, when a plurality of independent water channels are formed on the nozzle side in order to supply and drain cooling water, any of these water channels faces the supply port and the drain port formed in the plasma torch. Cooling water supply and drainage can be secured. For this reason, when attaching a nozzle to a plasma torch, it can be easily attached without requiring special positioning.

Further, a groove is formed in one or both of the supply port and the drain port formed in the plasma torch, and the circumferential distance from the end of the groove to the end of the other port is the nozzle side. It is set to a size larger than the circumferential width of the independent water channel formed on the circumference or the pitch on the circumferential surface of the independent water channel, so that the nozzle is mounted at any position when it is mounted on the plasma torch. However, the supply port and the drain port are not applied to one water channel, and each water channel can function as either a water channel for supplying cooling water to the nozzle or a water channel for discharging cooling water from the nozzle. I can do it. For this reason, the nozzle side can be cooled effectively.

Hereinafter, the most preferable form of the plasma torch according to the present invention will be described. Plasma torch according to the present invention is particularly fitted with nozzle (internal cooling type nozzle) forming a plurality of independent water passage which communicates with the annular passage so as to form an annular passage of the cooling water inside by combining a plurality of members It is configured so that effective cooling can be realized. However, even a conventionally used nozzle can be mounted without any trouble.

  When a general nozzle that has been conventionally used is attached to the plasma torch according to the present invention, the performance with respect to cutting and welding does not change at all, and it can be used without changing from the normal use procedure. is there.

  Further, when the internal cooling type nozzle is attached to the plasma torch according to the present invention, the internal cooling type nozzle is brought into contact with the surface where the independent water channel opens facing the surface where the supply port and the drainage port open in the plasma torch. Thus, it is preferable that any one of the plurality of independent water channels can communicate with the supply port and any other water channel can communicate with the drain port. By using such an internal cooling type nozzle, without limiting the mounting position of the internal cooling type nozzle with respect to the plasma torch, the rear end surface where the independent water channel opens, the supply port of the plasma torch, and the drain port are provided. It is possible to form a cooling water channel from the plasma torch via the internal cooling nozzle only by contacting the open surfaces.

  Therefore, the cooling water supplied to the plasma torch is surely supplied to the inside of the internal cooling type nozzle, and cools the wall portion that forms the plasma arc injection hole provided at the center of the internal cooling type nozzle. It becomes possible. For this reason, it becomes possible to improve the cooling effect on the plasma arc passing through the injection hole, and when energizing the same current as that of a general nozzle, the diameter of the injection hole is reduced to increase the current density and to improve the quality. In the case where the diameters of the general nozzle and the injection hole are the same, a larger current can be applied.

  The water channel formed in the plasma torch according to the present invention may be a circular hole like the cooling water passage formed in a general plasma torch, or may have another shape. In any case, the cross-sectional shape of the water channel is not particularly limited. In addition, the cross-sectional area of the water channel may be a value that can secure the required amount of water in consideration of conditions such as the average temperature of the cooling water to be supplied, heat exchange efficiency, and pipe resistance in the plasma torch.

  The supply port and the drain port are each connected to a water channel formed in the plasma torch. These supply port and drain port are opened on the nozzle mounting surface of the plasma torch, and the shape is not limited. That is, the supply port and the drain port may be circular, and may be a long hole, a square hole, or a hole having another shape.

  The shape of the nozzle mounting surface is not particularly limited, but when an internal cooling type nozzle is mounted, it is preferable to correspond to the shape of the opening surface of the independent water channel of the internal cooling type nozzle.

  In the plasma torch of the present invention, both or one of the supply port and the drain port is constituted by a groove extending in a plane intersecting with the axis of the water channel. That is, the groove is formed with a shape protruding from the cross section of the water channel. In particular, the opening areas of the supply port and the drain port are preferably larger than the cross-sectional area of the water channel. Furthermore, when the supply port and the drain port are constituted by grooves, it is preferable that these grooves are formed in an arc shape centering on the axis of the plasma torch.

  By configuring the supply port and the drain port with the grooves as described above, when the internal cooling type nozzle is opposed to the supply port and the drain port, any one of the plurality of water channels formed in the internal cooling type nozzle is Ensure communication. Accordingly, it is possible to realize more effective cooling by forming a cooling water passage inside the internal cooling type nozzle.

  When both or one of the supply port and the drain port are configured by grooves, the interval between the ends of these grooves or the interval between the groove and the end of the other port is formed in the internal cooling type nozzle. It is preferable that it is larger than the width (length on a plane) of an independent water channel. Thus, when the internal cooling type nozzle is mounted on the plasma torch by making the gap between the groove and the other port larger than the width of the water channel, both the supply port and the drain port are applied to one water channel. Therefore, it is possible to ensure that each water channel can function as either a cooling water supply port or a drain port.

  Next, a preferred embodiment of the plasma torch of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating the configuration of the plasma torch according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of a main part of the plasma torch shown in FIG. FIG. 3 is an explanatory view of the water supply / drainage member, and is a view for explaining the shapes of the cooling water supply port and the discharge port. FIG. 4 is a cross-sectional view illustrating the configuration of the internal cooling nozzle. FIG. 5 is a diagram for explaining the overlapping state of the water channel, the supply port, and the drain port when the internal cooling type nozzle is attached to the plasma torch.

  Prior to the description of the plasma torch B according to the present embodiment, an internal cooling type nozzle (hereinafter simply referred to as “nozzle”) A configured to realize the most advantageous cooling when attached to the plasma torch B. The configuration will be briefly described with reference to FIG. As described above, the conventional processing can be performed even if a conventional nozzle is attached to the plasma torch B according to the present invention.

  The nozzle A is configured to be able to inject a secondary airflow along with the plasma arc. However, it is not limited to the presence or absence of the secondary airflow, and is configured to be able to effectively cool the injection hole for injecting the plasma arc by forming a passage of cooling water inside the nozzle, It does not matter whether or not a secondary airflow exists around the plasma arc injected from the injection hole, or whether or not a higher-order airflow higher than the tertiary airflow exists.

The nozzle A has a wall portion 2a provided with an injection hole 1 for injecting a plasma arc at the center and an inner nozzle 2 serving as a first nozzle member, and a fitting portion for fitting the wall portion 2a of the inner nozzle 2 at the center. The secondary airflow passage 4 is formed between the outer nozzle 3 that has the fitting hole 3a that becomes the second nozzle member and the outer peripheral surface of the outer nozzle 3 that is disposed on the outer peripheral side of the outer nozzle 3, and the plasma A secondary airflow cap 5 having a jet outlet 5 a for ejecting an arc and a secondary airflow, and an insulator 6 disposed between the outer nozzle 3 and the secondary airflow cap 5 are configured.

  The inner nozzle 2 is formed with a wall portion 2a having an injection hole 1 formed at the center thereof, and a tapered end portion 2b (tapered surface 2b) is formed continuously from the wall portion 2a. A base portion 2c parallel to the axis is formed continuously with the large diameter portion. The wall 2a has a length and a thickness sufficient to form the length and diameter set in the injection hole 1, and is formed in a protruding shape from the end (tip) on the small diameter side of the taper 2b. Yes.

  The base portion 2 c is continuous with the tapered portion 2 b and is formed parallel to the axis of the nozzle A. In particular, the inner nozzle 2 is formed of a hexagonal bar, and the tapered part 2b and the wall part 2a are formed by cutting from the hexagonal bar. And the plane 2e functions as a surface constituting an independent water channel.

  Incidentally, the inner peripheral side of the inner nozzle 2 is formed as a surface 2 f constituting the plasma chamber 23 between the front surface of the electrode 11 when the nozzle A is attached to the main body 12 of the plasma torch B. A groove 2g for mounting the O-ring 7 is formed on the outer peripheral surface of the wall 2a and the outer peripheral surface of the base 2c.

  The outer nozzle 3 is formed with a fitting hole 3a for fitting a wall 2a formed in the inner nozzle 2 at the center, and a taper portion 3b (tapered surface 3b) having a diverging shape continuously from the fitting hole 3a. Further, a base portion 3c having a cylindrical inner surface 3d, which is parallel to the axis of the nozzle A and is continuous with the largest diameter portion of the tapered portion 3b, is formed.

  The fitting hole 3a can exhibit water-stopping properties by fitting the wall portion 2a formed in the inner nozzle 2 and contacting the O-ring 7 provided in the wall portion 2a. However, after fitting the fitting hole 3a and the wall 2a, for example, an adhesive is injected or brazed to ensure a higher water-stopping property.

  When the outer nozzle 3 and the inner nozzle 2 are fitted together, an annular cooling water passage 8 through which cooling water flows is formed between the tapered surface 2b and the tapered surface 3b. Further, the inner surface 3d of the base portion 3c is in contact with the divided piece 2d formed on the base portion 2c of the inner nozzle 2, and an independent water channel 9 is formed by the plane 2e and the inner surface 3d of the base portion 2c. Accordingly, the water channel 9 communicates with the annular cooling water passage 8 formed between the tapered surfaces 2 b and 3 b of the nozzles 2 and 3 and is configured as six independent water channels 9.

When the outer nozzle 3 and the inner nozzle 2 are integrated to form a combined body, the end surfaces 10 of the rear ends of the bases 2c and 3c of the nozzles 2 and 3 are substantially coincident with a surface orthogonal to the axis of the nozzle A. It becomes the same plane. When the nozzle A is mounted on the main body 12 of the plasma torch B, the end face 10 is in surface contact with the front end face 16a of the water supply / drainage member 16, and is connected to the water supply path 20 and the drainage path 21 formed in the water supply / drainage member 16. Is done.

That is, by attaching the nozzle A to the main body 12 of the plasma torch B, any of the at least three independent water channels 9 formed in the nozzle A communicates with the water supply channel 20 and any of the other water channels 9 Communicates with the drainage channel 21. Accordingly, the annular cooling water passage 8 formed in the nozzle A is connected to the water supply passage 20 via any one of the water passages 9 and simultaneously connected to the drainage passage 21 via any water passage 9. Will be constructed.

  A groove 3e for mounting the O-ring 7 is formed on the outer periphery of the base 3c of the outer nozzle 3.

  In the nozzle A configured as described above, when cooling water is supplied to any one or two of the six water channels 9 formed between the bases 2c and 3c of the inner nozzle 2 and the outer nozzle 3, supply is performed. The cooled cooling water is guided from the water passage 9 to the annular cooling water passage 8 and cooled by contacting the wall 2a in the cooling water passage 8, and then the water passage 9 on the side opposite to the water passage 9 on the supplied side. Drained from.

  Accordingly, all of the supplied cooling water surely flows through the annular cooling water passage 8, and in this process, the wall 2 a can be cooled to substantially cool the injection hole 1. For this reason, the cooling effect with respect to the plasma arc which passes the injection hole 1 increases, and it is possible to squeeze the plasma arc more finely.

  Next, the configuration of the plasma torch B according to the present embodiment will be described with reference to FIGS. The plasma torch B shown in the figure is described centering on the flow path of the cooling water supplied to the electrode 11 and the nozzle A.

  The plasma torch B is configured so that the electrode 11 can be attached to and detached from the electrode base 13 provided at the center of the main body 12. The plasma torch B has a hole 14 a for allowing plasma gas to pass through the outer periphery of the electrode 11 and has an insulating property. A cylindrical insulator 14 is disposed, and a nozzle A is further disposed on the outer periphery of the insulator 14. Then, by fastening the cap 15 engaged with the nozzle A to the main body 12, the rear end surface 10 of the nozzle A comes into surface contact with the surface 16 a of the cooling water supply / drainage member 16 provided on the main body 12, and the nozzle A and the insulation are provided. The body 14 is fixed to the main body 12.

  In the water supply / drainage member 16, the front end surface 16 a is formed as a surface perpendicular to the axis of the main body 12, and a recess 16 b for receiving the nozzle A is formed on the front end side. In particular, when the nozzle A is received in the concave portion 16b, the O-ring 7 disposed on the outer periphery of the base portion 3c of the outer nozzle 3 constituting the nozzle A comes into contact with the peripheral edge of the concave portion 16b and moves toward the secondary airflow passage side of the cooling water. It is configured to prevent leakage.

  The surface 16a of the water supply / drainage member 16 is configured to be in surface contact with the rear end surface 10 of the nozzle A over substantially the entire surface. For example, when the rear end surface 10 of the nozzle A is formed as a plane perpendicular to the axis, the surface 16a is formed as a plane perpendicular to the axis of the plasma torch. However, both the rear end surface 10 of the nozzle A and the surface 16a of the water supply / drainage member 16 may be tapered surfaces having the same angle with respect to the axis.

  The main body 12 is provided with a cooling pipe 17 in alignment with the central axis, and a cooling water supply pipe 18 is connected to the cooling pipe 17. By attaching the electrode 11 to the electrode base 13, a water channel 19 is formed in which the electrode 11 faces the open end side of the cooling pipe 17 and is continuous between the inner peripheral side and the outer peripheral side of the cooling pipe 17. The water channel 19 is a hole, is connected to a water supply channel 20 formed in the water supply / drainage member 16 through the inside of the main body 12, and is connected to the nozzle A from the water supply channel 20. Further, the water supply / drainage member 16 is formed with a drainage channel 21 at a position symmetrical to the water supply channel 20 with respect to the central axis, and a water channel 22 comprising a hole is connected to the drainage channel 21. Is connected.

  As shown in FIG. 3, the water supply channel 20 and the drainage channel 21 are configured by grooves formed in an arc shape centering on the axis of the plasma torch B with reference to holes forming the water channels 19 and 22, respectively. . However, it is not always necessary that both the water supply channel 20 and the drainage channel 21 are arc-shaped grooves, and at least one of them may be an arc-shaped groove. The lengths of the grooves constituting the water supply channel 20 and the drainage channel 21 have dimensions corresponding to the length of the independent water channel 9 formed in the nozzle A (the length at the rear end face 10).

  In the present embodiment, the water supply channel 20 and the drainage channel 21 are not formed on the basis of these lengths, but constitute the interval between the water supply channel 20 and the drainage channel 21, the water supply channel 20 and the drainage channel 21. The interval between the end portions of the grooves is set to a dimension larger than the width of the independent water channel 9 formed in the nozzle A, and the water supply channel 20 and the drain channel 21 are formed in the remaining portion of the dimension in the water supply / drainage member 16. . That is, when the nozzle A is attached to the water supply / drainage member 16 of the plasma torch B, it is not preferable that the independent water channel 9 formed in the nozzle A covers both the water supply channel 20 and the water discharge channel 21.

Therefore, when the nozzle A is attached to the plasma torch B as shown in FIGS. 5A and 5B by setting the interval between the water supply channel 20 and the drainage channel 21 with the dimensions of the water channel 9 as a reference, also mounting position of any state, never one waterway 9 water supply path 20, communicating with both the drainage channel 21.

In the plasma torch B configured as described above, when cooling water is supplied to the supply pipe 18, the supplied cooling water contacts the back surface of the electrode 11 through a water channel 19 formed inside the cooling pipe 17. Cooling. Thereafter, the water passes through a water channel 19 formed between the outer peripheral surface of the cooling pipe 17 and the electrode table 13, reaches a water supply channel 20 formed in the water supply / drainage member 16, and is supplied to the nozzle A. The cooling water supplied to the nozzle A cools the nozzle A, and then drains into the drainage channel 21 formed in the water supply / drainage member 16, and then passes through the channel 22 and a drain pipe (not shown) to the outside of the plasma torch B. Drained.

  In the state where the plasma torch B and the nozzle A are cooled as described above, a plasma gas is supplied to the plasma chamber 23 formed around the electrode 11 through the insulator 14, and between the electrode 11 and the nozzle A. A pilot arc is formed by discharging, and the pilot arc is injected from a nozzle A injection hole toward a workpiece (not shown). After the pilot arc reaches the workpiece, the electrode 11 and the workpiece are cut. Energize to form a plasma arc (main arc). The material to be cut is melted by the plasma arc and the melt is removed, whereby the portion of the removed base material is formed in the cut material as a groove penetrating in the thickness direction.

  Accordingly, the plasma torch B and the material to be cut are relatively moved in a desired direction in a state in which energization between the electrode 11 and the material to be cut is maintained, that is, in a state where a plasma arc is formed. A continuous groove is formed in the cutting material, whereby the material to be cut can be cut into a desired shape.

  The plasma torch B as described above can be selectively mounted with conventional nozzles or internal cooling type nozzles, and these nozzles can be mounted and used for plasma cutting or melt processing.

It is sectional drawing explaining the structure of the plasma torch concerning a present Example. It is sectional drawing to which the principal part of the plasma torch shown in FIG. 1 was expanded. It is explanatory drawing of a water supply / drainage member, and is a figure explaining the shape of the supply port and discharge port of a cooling water. It is sectional drawing explaining the structure of an internal cooling type nozzle. It is a figure explaining the overlapping state of a water channel, a supply port, and a drain port when an internal cooling type nozzle is attached to a plasma torch.

Explanation of symbols

A Nozzle B Plasma torch 1 Injection hole 2 Inner nozzle 2a Wall part 2b Tapered part, taper surface 2c Base part 2d Divided piece 2e Plane 2f Surface 2
2g groove 3 outer nozzle 3a fitting hole 3b taper portion, taper surface 3c base 3d inner surface 3e groove 4 secondary air flow passage 5 secondary air flow cap 5a secondary air flow outlet 6 insulator 7 O ring 8 cooling water passage 9 water passage 10 End face 11 Electrode 12 Main body 13 Electrode base 14 Insulator 14a Hole 15 Cap 16 Water supply / drainage member 16a Surface 16b Recess 17 Cooling pipe 18 Supply pipe 19, 22 Water path 20 Water supply path 21 Drainage path 23 Plasma chamber

Claims (1)

Circulating cooling water for cooling the nozzle by attaching the nozzle in which a plurality of independent water passage communicating with the annular passage and the annular passage of the cooling water is formed with injection holes for injecting the plasma arc is formed at the center A plasma torch having a water channel, comprising: a supply port connected to the water channel for supplying cooling water to the nozzle; and a drain port for discharging cooling water connected to the water channel and passing through the nozzle; The outlet and / or the drain outlet is formed by a groove connected to the water channel and extending in a plane crossing the axis of the water channel, and on the circumference of the ends of the two grooves. interval or one of the grooves end with the supply port or discharge port of width spacing on the circumference of a circle of independent waterways formed in the nozzle and the end portion or independent on the circumference of the water channel Dimensions larger than the pitch of When the nozzle is mounted, any independent water channel and supply port formed in the nozzle and any independent water channel and drain port formed in the nozzle can communicate with each other. A plasma torch characterized by comprising: