EP1922909B1 - Vapor plasma burner - Google Patents

Description

The invention relates to a steam plasma burner with a burner handle and a burner body, wherein in the burner body, a liquid supply, a heater, a combustion chamber, a cathode connected to the cathode holder and a nozzle formed as an anode is arranged with an outlet opening.

In water vapor plasma torches of the subject type, an arc between a negatively poled cathode and a positively poled anode, which is formed as a nozzle at the tip of the burner, ignited via a power source. Liquid or water is passed from a tank via a corresponding line to the burner and heated there by means of a heater to steam and passed through corresponding channels in the combustion chamber, where it generates a plasma as a plasma-forming medium. The plasma jet exits the nozzle without current, where it can be used to melt workpieces due to the high energy density. Since the plasma jet flows out of the nozzle of the burner without current and no arc is generated between the nozzle to the workpiece to be machined, non-conductive materials can be thermally processed. In addition to the cutting of workpieces can be carried out by means of a steam plasma burner also joining workpieces.

For example, this describes DE 100 08 255 A1 a steam plasma torch specifically designed to achieve lower energy levels at the plasma torch tip for other applications.

An arc plasma burner of the objective type, in which the container for the working fluid is integrated in the burner is in the EP 0 640 426 A1 described.

The EP 1 050 200 B1 describes a steam plasma burner, which is specially designed for the longest possible duration for a cutting process.

The US 3 242 305 A describes a plasma torch having an axially displaceable electrode. By lifting the electrode from the nozzle, a compact ignition can be made.

The JP 2004 268089 describes a water vapor plasma burner of the subject type with increased amount of storable liquid for a longer operational readiness.

The object of the present invention is to provide an above-mentioned water vapor plasma burner, which allows the most accurate ignition of the arc and can be cooled as well as possible for optimal operation.

The object of the invention is achieved by an abovementioned water vapor plasma burner, in which the liquid supply to the combustion chamber arranged in the burner body is designed such that the supplied liquid is first guided along the cathode holder via a cooling channel, and then runs along the heating device to the combustion chamber. By this measure, a steam plasma burner is provided, the cathode is better cooled by the liquid or the water. Due to the heat absorption of the liquid less energy is needed for the evaporation in the sequence.

Advantageously, a space bounded by a piston element is arranged around the cathode holder, which space is connected to the liquid feed line, so that the space is filled by supplying liquid and the cathode holder with the cathode lifts off from the nozzle.

In order to achieve an approximate sealing of the nozzle at rest of the plasma torch and to avoid damage to the cathode or nozzle by a distribution of forces, the shape of the tip of the cathode preferably coincides with the shape of the inside of the nozzle. When shaping, sharp edges or corners are preferably avoided.

Since the cathode and the cathode holder are formed axially displaceable, sealing rings are preferably arranged on the cathode holder. These sealing rings are formed of elastic material which can withstand the usual temperatures of water vapor plasma torches, for example of silicone compounds or Teflon composites. About the or the sealing rings can also be done centering of the cathode holder in the surrounding cylinder of the water vapor plasma burner.

In order to prevent a connection of the current-carrying cathode with other components of the steam plasma burner, the cathode holder has an electrically insulating coating. The coating should have a good electrical insulation but also a good heat conduction to dissipate the heat generated. In addition, a sealing of the insulating coating preferably takes place.

The cathode of the steam plasma burner according to a further feature of the invention consists of copper or a copper alloy.

In order to protect the cathode from the high temperatures that occur, it can be at least partially provided with an electrical insulation, in particular a ceramic coating.

In order to enable a rapid exchange of the cathode, this is preferably connected to the cathode holder via a thread. In order to achieve the best possible heat transfer from the cathode to the cathode holder, the thread is relatively long.

Preferably, the cathode has a stop flange which prevents the cathode from being turned too far into the cathode holder, which could lead to destruction of the thread. In addition, the joint between the cathode and cathode holder is sealed via the stop flange and prevents ingress of the working medium.

In order to prevent the cathode holder from twisting during assembly or disassembly of the cathode, a device for preventing rotation is preferably arranged on the cathode holder, which is formed, for example, by an axis which is arranged in a transverse hole of the cathode holder.

To ensure adequate cooling of the steam plasma burner achieve, the cathode holder is surrounded by at least one cooling channel, which is in communication with the liquid supply, so that a liquid, in particular water or a corresponding water mixture, is used as a cooling medium. In this case, the liquid is conveyed from the liquid feed line into a chamber around the cathode holder and conveyed along the at least one cooling channel around the cathode holder, so that the cathode holder is cooled by the liquid. Since the liquid of the steam plasma burner is used as the cooling medium, no separate cooling circuit with its own cooling medium needs to be arranged.

The at least one cooling channel runs along the cathode holder, preferably in a spiral shape. This guidance of the cooling channel ensures a uniform distribution of the water around the cathode holder. In addition to the cooling channel, it is advantageous if a narrow annular gap remains free around the entire cathode holder into which the cooling medium can penetrate. As a result, a secure wetting of the entire surface of the cathode holder is achieved and prevents local overheating of the cathode holder.

In order to keep the water vapor plasma burner compact in size, the liquid which has flowed around for cooling the cathode holder, this is returned to the heater via a return channel.

The heater preferably has a spiral channel for passing the liquid, in which it is evaporated. The spiral-shaped channel has the advantage that the liquid vaporized in the heating device, which is usually formed by an electric heater, is swirled and enters the combustion chamber in this swirling state.

In order to prevent commissioning of the steam plasma burner with not properly arranged housing, a circuit breaker may be provided which is actuated only when properly arranged housing. This circuit breaker may be formed by a micro-button, which is actuated by the properly screwed or plugged housing. First when the circuit breaker is closed, a supply of liquid and switching on the electrical supply is possible.

In order to enable cooling of the nozzle of the steam plasma burner, the nozzle may also have cooling channels for guiding a cooling fluid. A certain cooling of the nozzle can also take place in that the nozzle is connected via a thread to the housing. Thus, the heat generated at the nozzle can be dissipated via the thread to the housing.

To protect the nozzle from mechanical damage and to keep a certain minimum distance to the workpiece, a spacer can be arranged on the nozzle.

In this case, the spacer is preferably arranged annularly around the outlet opening.

The spacer may also be made in one piece with the nozzle.

Likewise, the spacer may be formed by a clip-on wire hanger. This offers a particularly simple and cost-effective implementation possibility. Likewise, the spacer may be formed by an attachable protective sleeve.

The spacer is formed from or coated with electrically insulating material. As a result, the current-carrying anode is isolated from the environment in an untransferred arc.

Further features will be apparent from the above description of the steam plasma burner.

• Fig. 1 eine schematische Darstellung eines Wasserdampf-Schneidgeräts;
• Fig. 2a und 2b schematische Darstellungen eines Wasserdampfplasmabrenners mit einer erfindungsgemäß axial verschiebbaren Kathode im Ruhezustand und in Betriebsstellung;
• Fig. 3a und 3b Schnittbilder einer Ausführungsform eines Wasserdampfplasmabrenners im Ruhezustand und im Betriebszustand; und
• Fig. 4 eine schematische Darstellung des Wasserdampfplasmabrenners mit dem Brennergriff und dem Brennerkörper.

The present invention will be explained in more detail with reference to the accompanying drawings. Show:

• Fig. 1 a schematic representation of a steam cutting device;
• Fig. 2a and 2b schematic representations of a steam plasma burner with an invention axially displaceable cathode at rest and in the operating position;
• Fig. 3a and 3b Sectional views of an embodiment of a steam plasma burner at rest and in the operating state; and
• Fig. 4 a schematic representation of the steam plasma burner with the burner handle and the burner body.

In Fig. 1 there is shown a steam cutting machine 1 having a base apparatus 1a for a water vapor cutting method. The base unit 1a comprises a power source 2, a control device 3 and a blocking element 4 associated with the control device 3. The blocking element 4 is connected to a container 5 and a steam plasma burner 6 comprising a burner handle 6a and a burner body 6b via a supply line 7 the steam plasma burner 6 can be supplied with a liquid 8 arranged in the container 5. The supply of the steam plasma burner 6 with electrical energy via lines 9, 10 from the power source. 2

For cooling the steam plasma burner 6 this is connected via a cooling circuit 11 at best with the interposition of a flow monitor 12 with a liquid container 13. When the burner 6 or the basic unit 1a is put into operation, the cooling circuit 11 can be started by the control device 3 and thus a cooling of the burner 6 via the cooling circuit 11 can be achieved. To form the cooling circuit 11, the burner 6 is connected via cooling lines 14, 15 with the liquid container 13.

Furthermore, the base unit 1a may have an input and / or display device 16, via which the most different parameters or operating modes of the steam cutting device 1 can be set and displayed. The parameters set via the input and / or display device 16 become the control device 3 forwarded, which controls the individual components of the steam cutting device 1 accordingly.

Furthermore, the steam plasma burner 6 can have at least one operating element 17, in particular a pushbutton 18. About the control element 17, in particular the button 18, the user can notify by activating and / or deactivating the button 18 of the control device 3 from the burner 6 that a steam cutting process should be started or performed. Furthermore, presettings can be made, for example, at the input and / or display device 16, in particular that the material to be cut, the liquid used and, for example, characteristics of the current and the voltage are predefined. Of course, further operating elements can be arranged on the burner 6, via which one or more operating parameters of the steam cutting device 1 are set by the burner 6. For this purpose, these controls can be connected directly via lines or via a bus system to the base unit 1a, in particular the control device 3.

The control device 3 activates after pressing the button 18, the individual components required for the steam cutting process. For example, first a pump (not shown), the blocking element 4 and the current source 2 are driven, whereby a supply of the burner 6 with the liquid 8 and electrical energy is introduced. Subsequently, the control device 3 activates the cooling circuit 11, so that a cooling of the burner 6 is made possible. By supplying the burner 6 with the liquid 8 and with energy, in particular with current and voltage, the liquid 8 is now in the burner 6 in a gas 19, in particular in plasma, converted at high temperature, so that by the burner from the sixth outflowing gas 19, a cutting process on a workpiece 20 can be performed.

The Fig. 2a and 2b show schematic representations of a steam plasma burner 6 according to the invention, in particular the burner nozzle 6b, in the idle state and in the operating state. The steam plasma burner 6 has a housing 21 in which a cathode 22 is arranged, which is connected to the power source 2. The anode 24 formed as a nozzle 23 is connected to the positive pole of the power source 2. At rest according to Fig. 2a the axially displaceable cathode 22 according to the invention is pressed against the nozzle 23. In this mode, no arc can be ignited between the cathode 22 and the anode 24 because of a short circuit. The heating device 25 contained in the steam plasma burner 6 for evaporating the water can already be switched on, so that the working medium is already preheated.

For igniting an arc between the cathode 22 and the anode 24, so a non-transmitted arc is in accordance with Fig. 2b switched on the supply of the working fluid in the present case, the liquid 8, whereby the axially displaceable cathode 22 lifts from the nozzle 23 and ignited in the presence of a corresponding current, an arc between the cathode 22 and the anode 24. The evaporated water in the heater is passed into the combustion chamber 27, where it serves as a medium for a plasma jet. The plasma jet is forced out through the opening 25 in the nozzle 23 and, because of its high energy density, can be used for cutting but also for joining workpieces 20.

Fig. 3a and 3b show an embodiment of a steam plasma burner 6, in particular burner insert, in a sectional view. According to Fig. 3a the water vapor plasma burner 6 is at rest, where the cathode 22 is pressed against the anode 23 formed as a nozzle 23. The steam plasma burner comprises a housing 21, a heater 26, a combustion chamber 27, in which the vaporized liquid 8 is formed as a medium for the plasma jet, which emerges through the outlet opening 25 of the nozzle 23. The cathode 22 is connected to a cathode holder 28, preferably via a screw thread 29. The cathode holder 28 is pressed against the nozzle 23 via a spring 30 (shown in dashed lines). Via a liquid feed line 32, the steam plasma burner 6 is supplied with the liquid 8. The cathode 22 is designed to be axially displaceable with the cathode holder 28. The liquid supply line 32 is available the cathode holder 28 in such a way that when the liquid is supplied, the cathode 22 is lifted from the nozzle 23, so that an arc between the cathode 22 and the anode 24 can be ignited. This happens because the liquid 8 is guided by the liquid supply line 32 into a space around the cathode holder 28, which is bounded by a piston element 31. By the water pressure, the piston member 31 is moved together with the cathode holder 28 and the cathode 22 against the force of the spring 30 to the rear, as in Fig. 3b shown.

The liquid 8 then passes via a cooling channel 33, which is preferably arranged spirally around the cathode holder 28, to a deflecting element 34, which is designed as a sealing ring 35. The sealing ring 35 also allows a centered mounting of the axially displaceable cathode holder 28. Via a return channel 36, the liquid 8 is returned to the heater 26, where it is evaporated in a spiral channel 37. Due to the helical arrangement of the channel 37, the vaporized liquid 8 in an annulus 38, which merges into the combustion chamber 27, swirled. The plasma-capable medium is formed by the arc between the cathode 22 and the anode 24 to a plasma jet, which emerges via the outlet opening 25 of the nozzle. In order to guarantee optimum heat dissipation from the cathode 22 to the cathode holder 28, the thread 29 for connecting the cathode 22 to the cathode holder 28 is formed as long as possible. So that the cathode 22 is not screwed too far into the cathode holder 28, there is a stop flange 39 at the cathode 22. The cathode 22 may be made of copper or a copper alloy at best with a ceramic coating. In order to secure the cathode holder 28 from twisting when the cathode 22 is screwed on or unscrewed, an anti-rotation protection can be arranged, which can be formed, for example, by an axis 40 in a transverse hole 41.

The nozzle 23 forms a further wearing part which can be exchanged, for example via a thread 42, with the housing 21 or another. Part of the steam plasma burner 6 may be connected. About a sealing ring 43 is a seal of the Nozzle 23 opposite the combustion chamber 27. At the nozzle 23, a spacer 44 may be arranged, which is arranged around the outlet opening 25 and the nozzle 23 from damage by contact of the workpiece 20 (not shown) protects. The spacer 44, which may be formed by a clip-on wire hanger or an attachable protective sleeve, is preferably formed from or coated with an electrically insulating material.

Finally, in the steam plasma burner 6, a circuit breaker 45 may be arranged, which is operable in a properly arranged housing 21. This ensures that operation of the steam plasma burner 6 is possible only when the housing 21 is properly fastened. As a result, injuries are effectively prevented by, for example, touching the heater 26.

In Fig. 4 is now the entire steam burner 6, so the burner handle 6a and the burner body 6b, shown schematically and partially cut, wherein schematically the connection of a hose assembly 46, in which all lines are summarized, indicated.

According to the invention, it is now apparent that a closed cooling circuit 11 has been created in the burner handle 6a by connecting the cooling circuit feed line 47 to the cooling circuit return line 48, for example via a connecting element 49. In addition, the connecting element 49 has a bypass line 50, which is connected to the liquid supply line 32 in the burner body 6b, as indicated schematically. The bypass line 50 preferably has a smaller cross section than the cooling circuit feed line 47 and the cooling circuit return line 48, so that only a small proportion of liquid 8 is taken from the closed cooling circuit 11 in the burner handle 6a. Of course, it is possible that for this purpose a corresponding element or valve in the connecting element 49 is arranged, via which the amount of liquid to be removed can be adjusted electronically or mechanically, so that only a certain amount or a certain volume is passed into the burner body 6b.

This configuration of the steam burner 6 now ensures that the user finds optimal cooling of the burner handle 6a and thus it can not happen that the heat transferred back from the burner body 6b heats the burner handle 6a to such an extent that the user can cause burns Handle of the torch handle 6a becomes so hot that the user can no longer pick it up. At the same time it is also achieved that a much higher flow velocity in the cooling circuit is made possible because a larger cross-section of the cooling circuit supply line 47 and the cooling circuit return line 48 can be used as if the cooling circuit 11 would be performed on the burner body 6b, as in the burner body 6a less space is available. This can also be transported away more heat returned.

Furthermore, this also ensures that when terminating a cutting process, the liquid 8 can be better recycled from the burner body 6b, as a Durckabfall arises and thus the liquid 8 is automatically withdrawn into the cooling circuit, ie, that when finishing the process, the pressure in the Cooling circuit inlet 47 and cooling circuit return line 48 is reduced, but in the burner body 6b, in particular in the liquid supply 32 due to the smaller cross section is still upright, so that the liquid 8 from the burner body 6b, in particular the liquid supply line 32, now in the cooling circuit 11, ie in the cooling circuit supply line 47 or cooling circuit return line 48, flows back and the hot liquid 8 is immediately removed via the cooling circuit 11 in the burner handle 6a. Thus, overheating of the torch body 6b after completion of the cutting process is prevented.

It is also possible that the bypass line 50 may have the same cross-section or diameter as the cooling circuit feed line 47 and the cooling circuit return line 48, since in the burner body 6b, in particular in the liquid feed line 32, a reduction in diameter or diameter reduction is performed, so that only as much liquid 8 to the combustion chamber 27, which is necessary for a cutting or welding process, wherein a Control of the amount of liquid 8, however, can be done via the pressure.

For the sake of completeness, it is also mentioned that additional lines, such as the power lines for the anode 24 and the cathode 22 as well as any control lines, have not been shown for the sake of clarity.

Furthermore is in Fig. 4 can be seen that the button 18 is designed as a safety switch 51, which ensures that when storing the steam burner 6, this safety switch 51 can not be activated. For this purpose, the safety switch 51 has a safety bar 52, which is arranged via a switching element 53. To actuate the switching element 53, the user must first press the safety bar 52 downwards or forwards so that he can then reach the switching element 53 with his finger. By the movement of the safety latch 52 is a release device, which may be executed for example by a micro-switch (not shown), activated, whereby a signal is sent to the control device 3 by pressing the switching element 53. By this release device ensures that only when you press the safety bar 52, the switching element 53 can be activated so that when a broken safety bar 52, the switching element 53 can not be activated.

Basically, it should be mentioned to the structure of the steam plasma burner 6 that the heat recovery of the parts in the region of the exit of the plasma jet 25 is of particular importance, so that overheating of the burner body 6b is prevented during operation. For this purpose, for example, the cathode 22 is designed accordingly, so that the heat from the region of the combustion chamber 27 can be passed into the underlying region of the cathode holder 28. For this purpose, in the region of the cathode holder 28, the cathode 22 has a plane or planar end face which, when screwed into the cathode holder 28, preferably has a full surface connection with the material of the cathode holder 28. This ensures that the rear stop of the cathode 22 with the cathode holder 28 is used for optimal heat dissipation and thus more heat energy via the screw thread 29 and the rear stop of the cathode 22 can be discharged.

Furthermore, the cathode holder 28 has a coating, in particular a ceramic coating with additional sealing layer, whereby an even better heat dissipation from the cathode holder 28 is given to the liquid 8 of the parallel running cooling channel. For this purpose, the ceramic coating for insulating the cathode holder 28 relative to the liquid 8 or other adjacent parts, whereas the sealing layer serves to seal the ceramic layer relative to the liquid 8, so that no liquid 8 can penetrate through the ceramic layer to the cathode holder. For example, the sealing layer is formed of resin base, whereby high temperature resistance is given. The Kermik layer preferably has a thickness of between 100 μm and 400 μm, in particular 200 μm.

In order to achieve an even better heat dissipation, the surface of the ceramic coating may have a certain structure, in particular the largest possible surface roughness (roughness depth), so that the surface is enlarged and thus more heat can be dissipated. Here, in the region of the seal of the cathode holder 28, a roughness depth of 0.2 .mu.m to 1 .mu.m, preferably 0.5 .mu.m, on, so that a permanent seal is given.

But it is also advantageous that for the exchange of the cathode 22, this at the threaded neck has a cylindrical portion which is between 2mm to 5mm in length, and whose outer diameter corresponds to the inner diameter of the screw thread 29 in the cathode holder 28. Thus, it is achieved that when attaching the cathode 22 on the cathode holder 28, a centering and alignment is achieved, so that by a simple rotational movement and pressure, the cathode can be easily screwed into the cathode holder 28. In addition, the cathode 22 in the region of the thread on a centering surface, which is arranged in the end region of the thread in the direction of the combustion chamber 27, that is, that the thread between the cylindrical portion and the centering surface is formed. The centering surface has a certain length between 2mm and 8mm, preferably 4.5mm.

Finally, it is also possible that the transverse hole 40 not only serves as torsion protection, but also as a defined stop when lifting the cathode 22, in particular of the cathode holder 22, is responsible.

Claims (17)

1. A vapor plasma burner (6) comprising a burner handle (6a) and a burner base (6b), wherein inside said burner base (6b) a liquid feed pipe (32), a heating device (26), a burner chamber (27), a cathode (22) connected to a cathode support (28), and an anode (24) which is configured as a nozzle (23) and has an exit opening (25) are arranged, characterized in that said liquid feed pipe (32) leading to said burner chamber (27), which pipe is arranged inside said burner base (6b), is configured in such a manner that a supplied liquid (8) is conducted first along said cathode support (28) via a cooling channel (33) and then along said heating device (26) towards said burner chamber (27).
2. A vapor plasma burner (6) according to claim 1, characterized in that a space is arranged around said cathode support (28), said space being limited by a piston element (31) and being connected to said liquid feed pipe (32), so that said space is filled when liquid (8) is supplied and said cathode support (28) and said cathode (22) are lifted off said nozzle (23).
3. A vapor plasma burner (6) according to claims 1 or 2, characterized in that the shape of the tip of said cathode (22) corresponds to the inside shape of said nozzle (23).
4. A vapor plasma burner (6) according to any one of claims 1 to 3, characterized in that sealing rings (35) are arranged on said cathode support (28).
5. A vapor plasma burner (6) according to any one of claims 1 to 4, characterized in that said cathode support (28) has an electrically insulating coating and preferably a sealing coating.
6. A vapor plasma burner (6) according to any one of claims 1 to 5, characterized in that said cathode (22) is made of copper or a copper alloy.
7. A vapor plasma burner (6) according to any one of claims 1 to 6, characterized in that said cathode (22) is, at least partially, provided with an electric insulation, particularly a ceramic coating.
8. A vapor plasma burner (6) according to any one of claims 1 to 7, characterized in that said cathode (22) is connected to said cathode support (28) via a thread (29).
9. A vapor plasma burner (6) according to claim 8, characterized in that said cathode (22) has a stop flange (39).
10. A vapor plasma burner (6) according to any one of claims 1 to 9, characterized in that an anti-distortion means is arranged on said cathode support (28), which means is e.g. formed by an axis (40) arranged in a transverse hole (41) of said cathode support (28).
11. A vapor plasma burner (6) according to any one of claims 1 to 10, characterized in that said cathode support (28) is surrounded by at least one cooling channel (33) connected to said liquid feed pipe (32), so that water may be used as a cooling medium.
12. A vapor plasma burner (6) according to claim 11, characterized in that said at least one cooling channel (33) runs around and along said cathode support (28), preferably in a spiral way.
13. A vapor plasma burner (6) according to any one of claims 1 to 12, characterized in that a return channel (36) is provided to return said liquid to said heating device (26).
14. A vapor plasma burner (6) according to any one of claims 1 to 13, characterized in that said heating device (26) has a spiral channel (37) to conduct said liquid.
15. A vapor plasma burner (6) according to any one of claims 1 to 14, characterized in that a protective switch is provided which may be actuated when the housing (21) is properly arranged.
16. A vapor plasma burner (6) according to any one of claims 1 to 15, characterized in that said nozzle (23) has cooling channels to conduct a cooling fluid.
17. A vapor plasma burner (6) according to any one of claims 1 to 16, characterized in that said nozzle (23) is connected to said housing (21) via a thread (42).

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