Wear Part for an Arc Torch and Plasma Torch, Arc Torch and Plasma Torch Comprising Same, Method for Plasma Cutting and Method for Producing an Electrode for an Arc Torch and Plasma Torch

Abstract

The invention relates to a wear part for an arc torch, plasma torch or plasma cutting torch, characterised in that the wear part or at least one part or a region of the wear part consists of an alloy formed from silver and zirconium, silver and hafnium, or silver and zirconium and hafnium.

Claims

1. A wearing part for an arc torch, plasma torch or plasma cutting torch, comprising at least a part or region of said wearing part comprises an alloy of one of silver and zirconium, silver and hafnium, and silver and zirconium and hafnium.

2. The wearing part of claim 1 further comprising the proportion of silver is between 60% and 97% of the volume or of the mass of said at least a part or region of said wearing part.

3. The wearing part of claim 1 further comprising the proportion of zirconium or hafnium is at least 0.05% of the volume or of the mass of said at least a part or region of said wearing part.

4. The wearing part, of claim 1 further comprising the proportion of zirconium or hafnium is at most 5%, of the volume or of the mass of said at least a part or region of said wearing part.

5. The wearing part, of claim 1 further comprising the remaining proportion up to 100% of the volume or of the mass of said wearing part is formed from copper up to at least 60%.

6. The wearing part of claim 1 further comprising said wearing part is an electrode for an arc torch.

7. The wearing part of claim 6 further comprising said electrode has a front end and a rear end, extends along a longitudinal axis M, and comprises at least an emission insert at said front end and an electrode holder.

8. The wearing part of claim 7 further comprising at least a sub-portion of an inner face of said electrode holder comprises said alloy.

9. The wearing part of claim 8 further comprising said alloy extends at least 0.5 mm radially outward from said at least a sub-portion of said inner face said electrode holder.

10. The wearing part of claim 7 further comprising said at least a sub-portion of said front face that directly adjoins said front face of said emission insert comprises said alloy.

11. The wearing part of claim 10 further comprising said sub-portion of said front face extends at least 0.5 mm radially outward.

12. The wearing part of claim 7 further comprising said emission insert comprises at least up to 90% of the volume or of the mass of one of hafnium, zirconium, and tungsten.

13. The wearing part of claim 1 further comprising said wearing part is a nozzle having at least one nozzle opening.

14. The wearing part of claim 13 further comprising at least a sub-portion of an inner face of said nozzle opening comprises said alloy.

15. The wearing part of claim 14 further comprising said alloy extends at least 0.5 mm radially outward at least from said sub-portion of said inner face of said nozzle opening.

16. The wearing part of claim 1 further comprising said wearing part is a nozzle protective cap having at least one nozzle protective cap opening.

17. The wearing part of claim 16 further comprising at least a sub-portion of an inner face of said nozzle protective cap opening comprises said alloy.

18. The wearing part of claim 17 further comprising said alloy extends at least 0.5 mm radially outward from said at least a sub-portion of said inner face of said nozzle protective cap opening.

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. A plasma cutting method for the plasma cutting of workpieces, by means of a plasma cutting torch comprising an electrode having an electrode holder and an emission insert, a nozzle, and a nozzle receptacle for the nozzle and an electrode receptacle for the electrode, wherein: during operation of the plasma cutting torch, above a predefined limit value for the burn-back of the emission insert an ignition of the pilot arc is suppressed to prevent or delay the destruction of the electrode during the cutting.

24. The method of claim 23 further comprising the limit value for the burn-back is at least 2.0 mm.

25. A method for producing an electrode for an arc torch, plasma torch, or plasma cutting torch, wherein the electrode has a front end and a rear end, extends along a longitudinal axis M and comprises at least an emission insert at the front end, an electrode holder, a holding element for the emission insert and a cavity that extends as far as the rear end and is open toward the rear end, wherein the method comprises: connecting the holding element to the electrode holder by thermal joining, in particular soldering or welding, from the direction of the cavity.

Description

[0043] Further features and advantages of the invention will emerge from the appended claims and from the following description of specific exemplary embodiments with reference to the drawings, in which:

[0044] FIG. 1: shows a sectional view of a plasma torch according to a specific embodiment of the present invention;

[0045] FIG. 2: shows a sectional view of an electrode of the plasma torch of FIG. 1;

[0046] FIG. 2.1: shows a view of the electrode of FIG. 2 from the front;

[0047] FIG. 2.2: shows a sectional view of an electrode holder of the plasma torch of FIG. 1;

[0048] FIG. 2.3: shows a further sectional view of the electrode of the plasma torch of FIG. 1;

[0049] FIG. 2.4: shows a sectional view of an emission insert of the electrode of FIG. 2;

[0050] FIG. 3: shows a sectional view of an electrode according to a further specific embodiment of the present invention;

[0051] FIG. 3.1: shows a view of the electrode of FIG. 3 from the front;

[0052] FIG. 3.2: shows a sectional view of an electrode holder of the electrode of FIG. 3;

[0053] FIG. 3.3: shows a view of a holding element of the electrode of FIG. 3 from the front;

[0054] FIG. 3.4: shows a sectional view of the holding element of FIG. 3.3;

[0055] FIG. 4: shows a sectional view of an electrode according to a further specific embodiment of the present invention;

[0056] FIG. 4.1: shows a view of the electrode of FIG. 4 from the front;

[0057] FIG. 4.2: shows a sectional view of an electrode holder of the electrode of FIG. 4;

[0058] FIG. 4.3: shows a sectional view of a holding element of the electrode of FIG. 4;

[0059] FIG. 5: shows a sectional view of an electrode according to a further specific embodiment of the present invention;

[0060] FIG. 5.1: shows a view of the electrode of FIG. 5 from the front;

[0061] FIG. 5.2: shows a sectional view of an electrode holder of the electrode of FIG. 5;

[0062] FIG. 5.3: shows a sectional view of a holding element of the electrode of FIG. 5;

[0063] FIG. 6: shows a sectional view of a nozzle according to a specific embodiment of the present invention;

[0064] FIG. 6.1: shows a further sectional view of the nozzle of FIG. 6;

[0065] FIG. 7: shows a sectional view of a nozzle protective cap according to a specific embodiment of the present invention; and

[0066] FIG. 7.1: shows a sectional view of the nozzle protective cap of FIG. 7.

[0067] FIG. 1 shows a sectional view of a plasma cutting torch 1 (however, it could also be an arc torch or a plasma torch) according to a specific embodiment of the present invention, having a nozzle cap 2, a plasma-gas-conducting unit 3, a nozzle 4 according to a specific embodiment of the present invention having a nozzle opening 4.1, a nozzle receptacle 5, an electrode receptacle 6 and an electrode 7 according to a specific embodiment of the present invention. The electrode 7 comprises an electrode holder 7.1 and an emission insert 7.3 with a length L1 of for example 3 mm (see FIG. 2.4). The plasma cutting torch 1 further comprises a nozzle protective cap receptacle 8, to which is fastened a nozzle protective cap 9 according to a specific embodiment of the present invention having a nozzle protective cap opening 9.1. The plasma cutting torch 1 also includes a secondary-gas-conducting unit 10. Secondary gas SG is fed through the secondary-gas-conducting unit 10. Additionally present on the plasma cutting torch 1 are a feed line for plasma gas PG, coolant return lines WR1 and WR2, and coolant feed lines WV1 and WV2. During operation, an arc or plasma jet burns between the emission insert 7.3 of the electrode 7 when cutting is taking place, flows through the nozzle opening 4.1 and the nozzle protective cap opening 9.1, and is constricted as a result, before it strikes a workpiece (not illustrated). The inner face of the nozzle opening 4.1 is denoted by the reference numeral 4.2 and that of the nozzle protective cap opening 9.1 is denoted by the reference numeral 9.2.

[0068] FIGS. 2 and 2.1 show the electrode 7 of FIG. 1, FIG. 2 being a sectional view through the electrode 7 and FIG. 2.1 being the view A of the front end of the electrode 7. The electrode 7 has a front end 7.1.8 and a rear end 7.1.9. The electrode 7 comprises the electrode holder 7.1, which is shown in FIG. 2.2, and the emission insert 7.3. The emission insert 7.3 is pressed in a bore 7.1.5 with a diameter D1 of e.g. 1.8 mm (−0.05) in the electrode holder 7.1. The bore 7.1.5 has an inner face 7.1.3, which is in touching contact with the outer lateral face 7.3.2 of the emission insert 7.3.

[0069] By way of example, the electrode holder 7.1 consists of an alloy of silver, copper and zirconium. The proportions of the mass are apportioned for example as follows: silver 97%, zirconium 2%, copper 1%. Here, the alloy has been used for the entire electrode holder 7.1 by way of example. It is also possible that the alloy is present only in a part or a region of the electrode holder 7.1. This is then preferably the case at least on the inner face 7.1.3 of the electrode holder 7.1. In that case, this region extends preferably at least 0.5 mm from the inner face radially outward. It is more preferable if the region extends at least 1 mm radially outward. This may be implemented e.g. in that the zirconium proportion and/or the silver proportion radially outwardly decrease(s) and the copper proportion increases.

[0070] FIG. 2.3, which shows a sectional view of the electrode 7, also shows a burn-back L2. The burn-back is defined as the difference between the face 7.3.1 of the emission insert 7.3 in the new state and the deepest point of the face burned back during operation. In the present example, L2=2 mm, for example.

[0071] In this example, the mass of the emission insert 7.3 preferably consists of hafnium to at least 97%.

[0072] FIG. 3 shows an electrode 7 according to a further specific embodiment of the invention, FIG. 3 being a sectional view through the electrode 7 and FIG. 3.1 being the view A of the front end 7.1.8 of the electrode 7. The electrode 7 has a front end 7.1.8 and a rear end 7.1.9. The electrode 7 comprises an electrode holder 7.1, which is shown in FIG. 3.1, a holding element 7.2, which is shown in FIGS. 3.3 and 3.4, and an emission insert 7.3. The emission insert 7.3 is pressed in a bore 7.2.1 with a diameter D5 in the holding element 7.2. The bore 7.2.1 has an inner face 7.2.3, which is in touching contact with the outer lateral face 7.3.2 of the emission insert 7.3.

[0073] The holding element 7.2 is pressed in the bore 7.1.5 in the electrode holder 7.1. The bore has an inner face 7.1.3, which is in touching contact with the outer lateral face 7.2.2 of the holding element.

[0074] By way of example, the holding element 7.2 consists here of an alloy of silver, copper and zirconium. The proportions of the mass are apportioned for example as follows: silver 97%, zirconium 2%, copper 1%. Here, the alloy is used for the entire holding element 7.2 by way of example.

[0075] The holding element 7.2 has a diameter D3 of for example 4 mm, the emission insert 7.3 has a diameter D7 (see FIG. 2.4) of for example 1.8 mm. This results in a wall thickness of the holding element of 1.1 mm and thus also a front circular ring face 7.2.5, which extends 1.1 mm radially outward.

[0076] It is also possible that the alloy is present only in a part or a region of the holding element 7.2. This is then preferably the case at least on the inner face 7.2.3 of the holding element 7.2. In that case, this region extends preferably at least 0.5 mm from the inner face 7.2.3 radially outward. It is more preferable if the region extends at least 1 mm radially outward. This may be implemented e.g. in that the zirconium proportion and/or the silver proportion radially outwardly decrease(s) and the copper proportion increases.

[0077] The electrode holder 7.1 consists at least of a material with good electrical conductivity, in this example consists of copper up to 90% of its mass.

[0078] In this example, the mass of the emission insert preferably consists of hafnium at least up to 97%.

[0079] FIG. 4 shows an electrode 7 according to a further specific embodiment of the invention, FIG. 4 being a sectional view through the electrode 7 and FIG. 4.1 being the view A of the front end 7.1.8 of the electrode 7. The electrode 7 has a front end 7.1.8 and a rear end 7.1.9. The electrode 7 comprises an electrode holder 7.1, which is shown in FIG. 4.2, a holding element 7.2, which is shown in FIG. 4.3, and an emission insert 7.3. The emission insert 7.3 is introduced in a bore 7.2.1 with a diameter D5 in the holding element 7.2.

[0080] The bore 7.2.1 in the holding element 7.2 has an inner face 7.2.3, which is in touching contact with the outer lateral face 7.3.2 of the emission insert 7.3.

[0081] The holding element 7.2 is pressed in a bore 7.1.5 in the electrode holder 7.1. The bore 7.1.5 has an inner face 7.1.3, which is in touching contact with the outer lateral face 7.2.2 of the holding element 7.2. In this respect, the holding element 7.2 may be connected to the electrode holder 7.1 by a force fit, form fit, or else by a thermal joining method, such as soldering, welding, in particular laser soldering, laser welding, arc soldering, arc welding, vacuum soldering, vacuum laser welding or electron-beam welding. It is particularly advantageous if the welding or soldering is performed from the rear end 7.1.9 and a seam (weld seam, soldered seam) 7.4 is located in a cavity 7.1.7 extending as far as the rear end. Also advantageous as a joining method is diffusion welding; pressure and temperature are applied here.

[0082] When the holding element 7.2 is thermally joined, e.g. soldered or welded, to the electrode holder 7.1 from the direction of the cavity 7.1.7, it has the following advantages over thermal joining from the front, for example: [0083] no seam visible from the front and [0084] no post-processing is necessary.

[0085] By way of example, the holding element 7.2 consists here of an alloy of silver, copper and zirconium. The proportions of the mass are apportioned for example as follows: silver 97%, zirconium 2%, copper 1%. Here, the alloy has been used for the entire holding element 7.2 by way of example.

[0086] The holding element 7.2 has a diameter D3 of for example 6 mm, the emission insert 7.3 has a diameter D7 of for example 1.8 mm. This results in a wall thickness of the holding element 7.2 of 2.1 mm and thus also a front circular ring face 7.2.5, which extends 2.1 mm radially outward.

[0087] It is also possible that the alloy is present only in a part or a region of the holding element 7.2. This is then preferably the case at least on the inner face 7.2.3 of the holding element 7.2. In that case, this region extends preferably at least 0.5 mm from the inner face radially outward. It is more preferable if the region extends at least 1 mm radially outward. This may be implemented for example in that the zirconium proportion and/or the silver proportion radially outwardly decrease(s) and the copper proportion increases.

[0088] The electrode holder 7.1 consists at least of a material with good electrical conductivity, in this example of copper up to 90% of its mass.

[0089] In this example, the mass of the emission insert preferably consists of hafnium at least up to 97%.

[0090] FIG. 5 shows an electrode 7 according to a further specific embodiment, FIG. 5 being a sectional view through the electrode 7 and FIG. 5.1 being the view A of the front end 7.1.8 of the electrode. The electrode 7 has a front end 7.1.8 and a rear end 7.1.9. The electrode 7 comprises an electrode holder 7.1, which is shown in FIG. 5.2, a holding element 7.2, which is shown in FIG. 5.3, and an emission insert 7.3. The emission insert 7.3 is introduced in a bore 7.2.1 with a diameter D5 in the holding element 7.2.

[0091] The bore in the holding element 7.2 has an inner face 7.2.3, which is in touching contact with the outer lateral face 7.3.2 of the emission insert.

[0092] The holding element 7.2 is fitted on the cylindrical portion on the outer face 7.1.1 of the electrode holder 7.1. In this respect, the holding element 7.2 may be connected to the electrode holder 7.1 by a force fit, form fit, or else by a thermal joining method, such as soldering, welding, in particular laser soldering, laser welding, arc soldering, arc welding, vacuum soldering, vacuum laser welding or electron-beam welding. It is particularly advantageous if the welding or soldering is performed from the rear end 7.19 and a seam (weld seam, soldered seam) 7.4 is located in a cavity 7.1.7 extending as far as the rear end. Also advantageous as a joining method is diffusion welding. Pressure and temperature are applied here.

[0093] By way of example, the holding element 7.2 consists here of an alloy of silver, copper and zirconium. The proportions of the mass are apportioned for example as follows: silver 97%, zirconium 2%, copper 1%. Here, the alloy has been used for the entire holding element 7.2 by way of example.

[0094] The holding element 7.2 has a diameter D3 of for example 10 mm, the emission insert has a diameter D7 of for example 1.8 mm. This results in a wall thickness of the holding element 7.2 of 4.1 mm and thus also a front circular ring face 7.2.5, which extends 4.1 mm radially outward.

[0095] It is also possible that the alloy is present only in a part or a region of the holding element 7.2. This is then preferably the case at least on the inner face 7.2.3 of the holding element 7.2. In that case, this region extends preferably at least 0.5 mm from the inner face radially outward. It is more preferable if the region extends at least 1 mm radially outward. This may be implemented e.g. in that the zirconium proportion and/or the silver proportion radially outwardly decrease(s) and the copper proportion increases.

[0096] The electrode holder 7.1 consists at least of a material with good electrical conductivity, in this example of copper up to 90% of its mass.

[0097] In this example, the mass of the emission insert preferably consists of hafnium at least up to 97%.

[0098] FIG. 6 shows a nozzle 4 according to a specific embodiment of the present invention, which is used by way of example in the plasma torch 1 of FIG. 1. This nozzle 4 may consist completely of an alloy of silver and zirconium, of silver and hafnium or of silver and zirconium and hafnium. However, it is essential that that region of the nozzle that can come into contact with the plasma jet or the arc consists of this material. This is the inner face 4.2 of the nozzle 4. This may be effected for example by fastening a nozzle insert 4.4 of said material in a nozzle mount 4.3. This is illustrated by way of example in FIG. 6.1.

[0099] In the present examples, in FIG. 6 the nozzle 4 and in FIG. 6.1 the nozzle cap insert 4.4 consist of an alloy of silver, copper and zirconium. The proportions of the mass are apportioned for example as follows: silver 97%, zirconium 2%, copper 1%. Here, the alloy has been used for the entire nozzle 4 by way of example.

[0100] In this context, the nozzle insert 4.4 may be connected to the nozzle holder 4.3 by a force fit, form fit, or else by a thermal joining method, such as soldering, welding, in particular laser soldering, laser welding, arc soldering, arc welding, vacuum soldering, vacuum laser welding or electron-beam welding. Also advantageous as a joining method is diffusion welding. Pressure and temperature are applied here.

[0101] FIG. 7 shows the nozzle protective cap 9 according to FIG. 1. This nozzle protective cap 9 may consist completely of e.g. an alloy of silver and zirconium, of silver and hafnium or of silver and zirconium and hafnium. However, it is essential that that region of the nozzle that can come into contact with the plasma jet or the arc consists of this material. This is the inner face 9.2 of the nozzle protective cap 9. This may be effected for example by fastening a nozzle protective cap insert 9.4 of said material in a nozzle protective cap holder 9.3. This is illustrated by way of example in FIG. 7.1.

[0102] In the present examples, in FIG. 7 the nozzle protective cap 9 and in FIG. 7.1 the nozzle protective cap insert 7.1 consist of an alloy of silver, copper and zirconium. The proportions of the mass are apportioned for example as follows: silver 97%, zirconium 2%, copper 1%. Here, the alloy has been used for the entire nozzle protective cap 9 by way of example.

[0103] In this context, the nozzle protective cap insert 9.4 may be connected to the nozzle protective cap holder 9.3 by a force fit, form fit, or else by a thermal joining method, such as soldering, welding, in particular laser soldering, laser welding, arc soldering, arc welding, vacuum soldering, vacuum laser welding or electron-beam welding. Also advantageous as a joining method is diffusion welding. Pressure and temperature are applied here.

[0104] It is possible for the features of the invention that are disclosed in the above description, in the drawings and in the claims to be essential to the implementation of the invention in their various embodiments both individually and in the optional combinations.

LIST OF REFERENCE SIGNS

[0105] 1 Arc torch, plasma torch, plasma cutting torch [0106] 2 Nozzle cap [0107] 3 Plasma-gas-conducting unit [0108] 4 Nozzle [0109] 4.1 Nozzle opening [0110] 4.2 Inner face of the nozzle opening [0111] 4.3 Nozzle holder [0112] 4.4 Nozzle insert [0113] 5 Nozzle receptacle [0114] 6 Electrode receptacle [0115] 7 Electrode [0116] 7.1 Electrode holder [0117] 7.1.1 Front face [0118] 7.1.2 Outer face [0119] 7.1.3 Inner face [0120] 7.1.5 Bore [0121] 7.1.7 Cavity [0122] 7.1.8 Front end [0123] 7.1.9 Rear end [0124] 7.2 Holding element [0125] 7.2.1 Bore [0126] 7.2.2 Outer lateral face [0127] 7.2.3 Inner face [0128] 7.2.5 Front circular ring face [0129] 7.3 Emission insert [0130] 7.3.1 Front face [0131] 7.3.2 Outer lateral face [0132] 7.4 Seam [0133] 8 Nozzle protective cap receptacle [0134] 9 Nozzle protective cap [0135] 9.1 Nozzle protective cap opening [0136] 9.2 Inner face of the nozzle protective cap opening [0137] 9.3 Nozzle protective cap holder [0138] 9.4 Nozzle protective cap insert [0139] 10 Secondary-gas-conducting unit [0140] D1 Inner diameter [0141] D3 Outer diameter [0142] D5 Inner diameter [0143] D7 Diameter [0144] L1 Length [0145] L2 Burn-back [0146] M Central longitudinal axis [0147] PG Plasma gas [0148] SG Secondary gas [0149] WR1 Coolant return line [0150] WR2 Coolant return line [0151] WV1 Coolant feed line [0152] WV2 Coolant feed line