Device for thermally coating a surface

Abstract

The invention relates to a device for thermally coating a surface, which has at least one housing, a cathode, which is designed as a consumable wire and at least one insulation element, wherein the housing has a non-detachable anti-adhesion layer.

Claims

1. A device for thermally coating a surface, comprising: at least one housing; a cathode; an anode designed as a consumable wire; and at least one insulation element embodied as a nozzle ring, wherein an outer surface of the entire device comprises an outer surface of the housing and an outer surface of the nozzle ring; wherein the outer surface of the housing is a non-detachable metallic anti-adhesion surface, and wherein the outer surface of the nozzle ring is the only insulator on the outer surface of the entire device, and all other insulators of the device are situated within the housing.

2. The device of claim 1, wherein the non-detachable metallic anti-adhesion surface of the housing is composed of polished brass.

3. The device of claim 1, wherein the outer surface of the nozzle ring is oriented away from the cathode and composed of ceramic material polished to a mirror finish.

4. The device of claim 1, wherein the outer surface of the nozzle ring is an anti-adhesion surface which has been polished to a mirror finish.

5. The device of claim 1, wherein the outer surface of the housing has a hard-chrome coating as an anti-adhesion surface.

6. The device of claim 1, wherein the outer surface of the housing has a protective aluminum oxide layer as an anti-adhesion surface.

7. The device of claim 1, wherein the outer surface of the housing has a protective zirconium oxide layer as an anti-adhesion surface.

8. The device of claim 1, wherein the outer surface of the housing has an aluminum layer as an anti-adhesion surface.

9. The device of claim 8, wherein the aluminum layer is oxidized, forming a protective aluminum oxide layer.

10. A device for thermally coating a surface, comprising: a two-part housing including a main element and a cover element; a cathode; an anode; a primary gas distributor; a secondary gas distributor; and a nozzle ring having a polished insulating outer surface oriented away from the cathode, wherein the anode is designed as a consumable wire and is guided into a secondary gas nozzle by means of a wire guide; wherein the two-part housing is configured to accommodate the wire guide completely within the main element thereof; wherein a primary gas nozzle is mounted in a centered manner on the primary gas distributor with the secondary gas distributor connected in parallel; wherein an outer surface of the entire device comprises an outer surface of the two-part housing and the outer surface of the nozzle ring; wherein the outer surface of the two-part housing is a non-detachable metallic anti-adhesion surface; and wherein the outer surface of the nozzle ring is the only insulator on the outer surface of the entire device, and all other insulators of the device are situated within the housing.

11. The device of claim 10, wherein the primary gas nozzle has openings arranged radially in one plane on a side oriented toward the secondary gas nozzle.

12. The device of claim 11, wherein the nozzle ring is formed from an electrically and thermally insulating element, and wherein the primary gas nozzle directs gas through a central opening of the nozzle ring.

13. The device of claim 12, wherein the nozzle ring further comprises a plurality of holes centrally arranged in a common plane.

14. The device of claim 12, wherein the nozzle ring further comprises each of an annular slot and a plurality of holes tangentially arranged along a plurality of planes.

15. The device of claim 13, wherein the nozzle ring further comprises each of an annular slot and a plurality of tangential labyrinth holes.

16. A method for thermally coating a surface, comprising: striking an electric arc directly between a cathode and an anode of a thermal coating device, wherein said anode is a consumable wire configured to be guided by a wire guide accommodated completely within a housing of the device; flowing a first process gas stream around the electric arc from a primary gas nozzle; and flowing a second process gas stream around the first process gas stream, wherein the first process gas stream is flowed through a plurality of holes or slots in the primary gas nozzle, arranged radially thereon in a first common plane, said holes oriented away from the cathode, wherein the second process gas stream is flowed through a nozzle ring having an insulating outer surface which is polished to a mirror finish, said nozzle ring further including a central opening through which the first process gas stream from the primary gas nozzle flows, wherein an outer surface of the entire device comprises an outer surface of the housing of the device and the outer surface of the nozzle ring, wherein the outer surface of the housing is a non-detachable metallic anti-adhesion surface, and wherein the outer surface of the nozzle ring is the only insulator on the outer surface of the entire device, and all other insulators of the device are situated within the housing.

17. The method of claim 16, wherein flowing the second process gas stream from the nozzle ring includes atomizing a molten portion of the anode and accelerating said molten portion away from the cathode in a direction of the electric arc.

18. The method of claim 16, wherein the first process gas stream is a noble gas stream produced in a continuous manner, and wherein the second process gas stream is an air stream produced in a pulse manner.

19. The method of claim 16, wherein flowing the second process gas stream through the nozzle ring further includes flowing the second process gas stream through each of an annular slot extending in a first plane of the nozzle ring and a plurality of tangentially arranged holes at a second common plane of the nozzle ring.

20. The device of claim 10, wherein the two-part housing has a predominantly circular cross-section which is flattened only in a region of the nozzle ring, and wherein there is an oblique transition from a portion of the two-part housing having a circular cross-section of the two-part housing to a plane in which the nozzle ring is arranged.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous details and effects of the invention will be explained in more detail below on the basis of various exemplary embodiments illustrated in the figures. In the figures:

(2) FIG. 1A shows an exploded view of a device for thermally coating a surface.

(3) FIG. 1B shows a section through a device according to FIG. 1A.

(4) FIG. 2 shows a nozzle ring as a detail in a first embodiment.

(5) FIG. 3 shows a nozzle ring as a detail in a second embodiment.

(6) FIG. 4 shows a first possible embodiment of an anti-adhesion surface of the nozzle ring, wherein the nozzle ring is of multipart design and has a partial anti-adhesion and/or insulating surface or layer on the inside.

(7) FIG. 5 shows a second possible embodiment of an anti-adhesion surface of the nozzle ring, wherein the nozzle ring is of multipart construction and has an extended configuration.

(8) FIG. 6 shows a third possible embodiment of an anti-adhesion surface of the nozzle ring, wherein the nozzle ring 13 is of single-part construction and has an extended configuration.

(9) FIG. 7 shows a first possible embodiment of a shielding gas flow, wherein a shielding gas nozzle includes a plurality of holes centrally arranged in a common plane.

(10) FIG. 8 shows a second possible embodiment of a shielding gas flow, wherein a shielding as nozzle includes a plurality of holes tangentially arranged in a common plane.

(11) FIG. 9 shows a third possible configuration, wherein a shielding as nozzle includes a plurality of holes tangentially arranged in a plurality of planes.

(12) FIG. 10 shows a fourth possible embodiment of a shielding as flow, wherein a shielding as nozzle includes each of a slot and a plurality of holes tangentially arranged in a plurality of planes.

(13) FIG. 11 shows a fifth possible embodiment of a shielding as flow, wherein a shielding gas nozzle includes each of a slot and a plurality of tangential labyrinth holes.

DETAILED DESCRIPTION OF THE DRAWINGS

(14) In the different figures, identical parts are always provided with the same reference signs, and so said parts are generally also described only once. In FIGS. 2 and 3, the components are each shown in perspective from both sides, i.e. from a lower side and an upper side. In FIGS. 7 to 11, a cross section and a plan view are shown in each case.

(15) FIG. 1A shows a device 1 for thermally coating a surface. The device 1 can be referred to as a torch 1, which is suitable for thermally coating a cylinder bore, even one of relatively small diameter of less than 60 mm. For this purpose, an arc is struck in the device 1, said arc melting the sprayed filler material, wherein molten material is carried to the surface to be coated. For this purpose, two gases, namely primary gas and secondary gas, are used. The purpose of the primary gas is to maintain or support the arc, and the primary gas additionally has cooling functions. The secondary gas also has a dual function. On the one hand, the secondary gas is intended to assist transfer of the molten particles and to further atomize and accelerate the particles. On the other hand, the secondary gas has a cooling function, further details of which will be given below. The primary gas can be argon, nitrogen, a mixture of inert gases, or a mixture of the gases given by way of example with hydrogen and/or helium. The secondary gas can be air or compressed air. It is also possible for argon, nitrogen or other inert gases to be used as the secondary gas. Of course, the gases mentioned by way of example are not intended to be restrictive.

(16) The device 1 can have a head part 2, a connector 3 as an intermediate part and an adapter 4 as a connection part, while primary gas connections, secondary gas connections, power source connections, control and monitoring devices and a wire are not shown in FIG. 1A. To coat a cylinder bore, the device rotates upon itself and at the same time is moved linearly backward and forward. Of course, a linear motion of the component to be coated can also be performed instead of the linear motion of the device. Of course, the same also applies to the rotary motion, where expedient.

(17) As illustrated by way of example, the device 1 for thermally coating a surface comprises a two-part housing 6 having a main element 7 and a cover element 8, a cathode 9, a primary gas distributor 11, a secondary gas distributor 12, electrically and thermally acting insulation elements 13, 14 and 16, and an anode, which is designed as a consumable wire and is guided into a secondary gas nozzle 19 by means of a wire guide, wherein a primary gas nozzle 21 is mounted in a centered manner on the primary gas distributor 11 with the secondary gas distributor 12 connected in parallel, and wherein the primary gas nozzle 21 has openings, i.e. holes or slots, arranged radially in one plane on its side 22 oriented toward the secondary gas nozzle 19.

(18) It is expedient if the insulation elements are embodied by a plurality of components in the form of a nozzle ring 13, nozzle insulator 14 and main insulator 16, for example.

(19) The nozzle ring 13 is made from a ceramic material, preferably from a high-performance ceramic material, and has an electrically and thermally insulating effect between the housing 6 and the wire guide. The nozzle ring 13 is the only external insulator in the otherwise metallic external form of the entire device or housing 6.

(20) In one possible embodiment, the nozzle ring 13 is of funnel-shaped design and extends from an outer ring 24 in the direction of a central opening 25 (FIG. 2). It is also possible to embody the nozzle ring 13 in the manner of a sleeve (FIG. 3) with a wall portion 27 extending away from a base flange 26, thus forming an extended version of the nozzle ring 13.

(21) In a preferred configuration of both embodiments, the nozzle ring 13 is polished, preferably to a mirror finish, at least on the outer surface 28 thereof which faces away from the cathode 9, in order to avoid adhesions. The nozzle ring 13 can be of single-part or multipart construction, wherein ceramics or materials such as silicon nitride, aluminum nitride, boron nitride, zirconium oxide, aluminum oxide, ATZ or ZTA can preferably be used to produce the nozzle ring.

(22) In order to avoid adhesions on the nozzle ring 13, a number of measures can be provided:

(23) The nozzle ring 13 is of multipart design and has a partial anti-adhesion and/or insulating surface or layer 29 on the inside (FIG. 4).

(24) The nozzle ring 13 is of single-part design and has a partial anti-adhesion and/or insulating surface or layer 29 on the inside and on the outside.

(25) The nozzle ring 13 is of multipart construction and has an extended configuration (FIG. 5).

(26) The nozzle ring 13 is of single-part construction and has an extended configuration (FIG. 6).

(27) The nozzle ring 13 is of single-part construction, being embodied as a shielding gas nozzle with holes 30 centrally in one plane (FIG. 7).

(28) The nozzle ring 13 is of single-part construction, being embodied as a shielding gas nozzle with holes 30 tangentially in one plane (FIG. 8).

(29) The nozzle ring 13 is of single-part construction, being embodied as a shielding gas nozzle with holes 30 tangentially in a plurality of planes (FIG. 9).

(30) The nozzle ring 13 is of single-part construction, being embodied as a shielding gas nozzle with a slot 31 and holes 30 tangentially in a plurality of planes (FIG. 10).

(31) The nozzle ring 13 is of multipart construction, being embodied as a shielding gas nozzle with a slot 31 and tangential labyrinth holes 32 (FIG. 11).

(32) It is advantageous if a shielding gas flow is introduced into the nozzle opening 33 in order to avoid and/or remove reflected and/or deflected particles, wherein the shielding gas flow is produced continuously and/or in a pulsed manner around the spray jet. The nozzle opening 33 is arranged in the flattened part of the housing 6, i.e. the main element 7 thereof, and is also defined by the surface 28 of the nozzle ring 13. The spring jet emerges from the nozzle opening 33. To produce the shielding gas flow, the process gases can be used, all that is necessary being to divert them, and it is possible, in particular, to feed in the secondary gas as the shielding gas. It is also possible to supply other gases as process gases, e.g. air, argon or other gases. The shielding gas can flow through centrally arranged holes 30 and/or tangentially arranged holes 30 in one or more planes of the nozzle ring 13. Moreover, flow can take place through slotted nozzles 31 and/or slotted nozzles 31 with centrally and/or tangentially arranged holes 30 in one or more planes of the nozzle ring 13 in order to stabilize the shielding gas flow. Moreover, the shielding gas flow can take place through slotted nozzles 31 with a labyrinth 32 comprising centrally arranged holes/slots 30/31 and/or tangentially arranged holes/slots 30/31 in order to stabilize the shielding gas flow. The shielding gas forms as it were a protective shield to protect the surface 28, protecting the surface 28 of the nozzle ring 13, i.e. of the nozzle opening 33, from the deposition of said particles.

(33) As already mentioned, the housing 6 is of two-part design by way of example, with the main element 7 and the cover element 8, and this is beneficial for ease of maintenance. As is apparent, the housing 6 is of a predominantly round design. Only in the region of the nozzle opening 33 is the circular configuration of the housing 6, i.e. of the main element 7, as seen in cross section abandoned. Here, the housing 6 is flattened, wherein there is an oblique transition to a plane in which the nozzle ring 13 or nozzle opening 33 is arranged. The consistent retention of the circular housing 6 as seen in cross section avoids a blade effect, i.e. the process gases or air in a cylinder bore being taken along, thereby considerably reducing a negative influence of the blade effect on the particles to be transported in the direction of the surface to be coated. This flow-optimized surface configuration also has an effect in reducing deposits on the housing.

(34) The cover element 8 can be screwed to the main element 7 to form the housing 6 by means of screws 34.

(35) The housing 6 is preferably formed from brass and has an anti-adhesion surface 36. The anti-adhesion surface 36 can be embodied in such a way that the material of the housing 6 is polished in order to reduce roughness, counteracting deposition on the housing 6. The same applies to the spindle, which is not shown in the figures. As an anti-adhesion surface 36, the housing 6 can also have a coating of a metallic or, preferably, ceramic kind. In the case of the illustrative embodiment shown in FIG. 1B, the anti-adhesion surface 36 is applied as a coating, for example. In FIG. 1B, an anti-adhesion surface 36 of the main element 7 can be seen, by way of example, while a nozzle ring is not visible. Of course, the cover element 8 can also have an anti-adhesion surface.

(36) The invention provides a single-wire spring device 1 which rotates upon itself, by means of which even cylinder bores of relatively small diameter can be coated. The arc to be struck is struck directly between the cathode and the anode, i.e. on the wire, and not between the cathode and the plasma gas nozzle as hitherto known in the known devices, in which the service life was shortened by the effect of the arc, especially at relatively high current intensities. In the invention, the primary gas nozzle 21 is cooled by the secondary gas, for which reason the openings, i.e. slots, are provided. By means of the components comprising the nozzle insulator 14, the nozzle ring 13, the secondary gas nozzle 19, the primary gas distributor 11 and the secondary gas distributor 12, which are preferably formed from a ceramic material, an internal thermal and electrical insulation is as it were advantageously formed. The nozzle ring 13 is virtually the only external insulator in the otherwise metallic external form of the entire device or housing. The wire guide with its components is accommodated completely within the housing 6, i.e. in the main element 7, making it possible to omit external protective measures. Sealing elements 35 can also be seen in FIG. 1A.

LIST OF REFERENCE SIGNS

(37) 1 device for thermal coating 2 head part 3 connector 4 adapter 6 housing 7 main element 8 cover element 9 cathode 11 primary gas distributor 12 secondary gas distributor 13 nozzle ring 14 nozzle insulator 16 main insulator 19 secondary gas nozzle 21 primary gas nozzle 22 side 11 oriented toward 19 24 outer ring 25 central opening 26 base flange 27 wall portion 28 outer surface 29 anti-adhesion and/or insulating layer 30 holes 31 slot 32 labyrinth holes 33 nozzle opening 34 screws 35 sealing elements 36 anti-adhesion surface