Cooling tube for a plasma arc torch and spacer

Abstract

The invention relates to a cooling pipe for a plasma arc torch, comprising a hollow cylindrical electrode body having a central internal core, at the front end of which an electrode core holder having an electrode core inserted therein is arranged, and a hollow cylindrical cooling pipe which is inserted into the internal bore in a sealing manner and which features an internal bore that form a cooling channel as a feed and, in the intermediate space between the outer circumference of the internal bore and the inner circumference of the electrode body, forms a cooling channel formed as a return, wherein the cooling pipe has, on the inner side thereof that is facing the electrode core holder, space-maintaining means (e.g. a spacer washer or wires or rods), which are suitable to rest on the front end of the electrode core holder.

Claims

1. A cooling tube for a plasma arc torch, wherein the cooling tube (4), on an inside thereof facing toward an electrode core holder (12) of an electrode body into which the cooling tube is inserted, comprises a circular spacer disk configured and placed within an inside of the cooling tube spaced from a front end (16) of the cooling tube (4) so as to directly contact with the electrode core holder in face-end engagement, wherein the circular spacer disk comprises a cross-bar extending along at least one diameter of the circular spacer disk and configured to engage a stop face (26) at a free end of the electrode core holder (12) such that a space is defined between the front end (16) of the cooling tube (4) and a bore bottom (27) of the electrode body (1) and the front end (16) of the cooling tube (4) extends beyond the electrode core holder (12) when the cooling tube (4) is inserted in the electrode core holder (12).

2. A cooling tube according to claim 1, wherein the circular spacer disk is connected integrally with the cooling tube (4).

3. A cooling tube according to claim 1, wherein the circular spacer disk (13) is releasably connected to the cooling tube (4).

4. A cooling tube according to claim 3, wherein the circular spacer disk (13) has an outer circumference that engages in a sealing manner against the inner circumference of the cooling tube (4), the coolant flow passing through the circular spacer disk (13).

5. A cooling tube according to claim 1, wherein on the outer circumference of the cooling tube (4) at least two pressure vanes (23, 23a, 23b, 23c, 23d) are disposed offset relative to one another, the at least two pressure vanes are acted upon by a cooling medium in a cooling channel (8) configured as a return passage and press the cooling tube (4) against an electrode-side fastening device.

6. A cooling tube according to claim 5, wherein the pressure vanes (23, 23a, 23b, 23c, 23d) are configured in such a way that a vortex flow (24) directed downstream of the cooling channel (8) can be generated.

7. A cooling tube according to claim 5, wherein the pressure vanes (23, 23a, 23b, 23c, 23d) are configured in such a way that an (axial) pressure force (25) directed in the longitudinal direction of the cooling tube (4) can be exerted on the fastening device of the cooling tube (4) on the electrode side in the electrode body (1).

8. A cooling tube according to claim 5, wherein the pressure vanes (23a) are configured as flaps tapered in the direction towards the longitudinal axis of the cooling tube (4).

9. A cooling tube according to claim 5, wherein the pressure vanes (23b) are configured as propeller wings tapered in the direction towards the longitudinal axis of the cooling tube (4).

10. A cooling tube according to claim 1, wherein the circular spacer disk comprises two perpendicular cross elements extending within the circular spacer disk defining passage openings through which the cooling medium can flow, the two perpendicular cross elements forming a center cross that directly abuts the electrode core holder.

11. A cooling tube for a plasma arc torch, comprising: a circular spacer disk disposed on an inside of the cooling tube spaced from a front end (16) of the cooling tube (4) facing toward a central electrode core holder (12) extending longitudinally inward from a closed end of an electrode body into which the cooling tube is inserted, the circular spacer disk and comprising a cross-bar extending along at least one diameter of the circular spacer disk and configured and placed to directly contact a free end of the central electrode core holder in face-end engagement such that a space is defined between the front end (16) of the cooling tube (4) and a bore bottom (27) of the electrode body (1) and the front end of the cooling tube (4) extends beyond the electrode core holder (12) when the cooling tube (4) is inserted in the electrode core holder (12), and at least two pressure vanes (23, 23a, 23b, 23c, 23d) protruding from an outer circumference of the cooling tube (4) and disposed offset relative to one another, wherein the at least two pressure vanes are acted upon by a cooling medium in a cooling channel (8) configured as a return passage and thereby press the cooling tube (4) against an electrode-side fastening device.

12. A cooling tube according to claim 11, wherein the circular spacer disk comprises two perpendicular cross elements extending within the circular spacer disk defining passage openings through which the cooling medium can flow, the two perpendicular cross elements forming a center cross that directly abuts the electrode core holder.

13. A plasma arc torch comprising: an electrode body having a central internal bore and a central electrode core holder integrally connected to and extending longitudinally from a closed end of the electrode body; an electrode core inserted in the electrode core holder; a cooling tube inserted into the electrode body and comprising a hollow bore through which a cooling medium flows in a direction toward the electrode core holder of the electrode body; and a circular spacer disk disposed on an inside of the cooling tube spaced from a front end (16) of the cooling tube (4) and comprising two perpendicular cross elements extending within the circular spacer disk defining passage openings through which the cooling medium can flow, the two perpendicular cross elements forming a center cross that directly abuts at a free end of the electrode core holder in face-end engagement such that a space is defined between the front end (16) of the cooling tube (4) and a bore bottom (27) of the electrode body (1) and the front end of the cooling tube (4) extends beyond the electrode core holder (12) when the cooling tube (4) is inserted in the electrode core holder (12).

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention will now be described in detail with reference to drawings illustrating a number of ways of carrying out the invention. Further features essential to the invention and advantages of the invention will be apparent from the drawings and from their description.

(2) In the drawings:

(3) FIG. 1 shows a longitudinal section through a plasma electrode for a plasma arc torch in a first embodiment of a cooling tube

(4) FIG. 2 shows the front view of the cooling tube shown in a sectional view in FIG. 1, with a spacer disk

(5) FIG. 3 shows the sectional view through the cooling tube according to FIG. 1 in a modified embodiment with illustration of additional functions

(6) FIG. 4 shows a sectional view through the electrode body according to FIG. 1 in a modified embodiment

(7) FIG. 5 shows a perspective view of a ring with pressure vanes

(8) FIG. 6 shows the front view of the cooling tube at the height of the pressure vanes shown in FIG. 3

(9) FIG. 7 shows an embodiment of pressure vanes modified from FIG. 5

(10) FIG. 8 shows a perspective view of a threaded ring with pressure vanes

(11) FIG. 9 shows an embodiment of pressure vanes in the manner of propeller wings, modified from FIGS. 5 and 6

(12) FIG. 10 shows an embodiment of a cooling tube with a releasably inserted spacer disk, modified from FIG. 3

(13) FIG. 11 shows a perspective view of the spacer disk releasably inserted in FIG. 8

(14) FIG. 12 shows a sectional view through the front end of the cooling tube with illustration of a wire or rod as a substitute for the spacer disk

(15) FIG. 13 shows a sectional view through the front end of the cooling tube with illustration of a plurality of wires or rods as substitutes for the spacer disk

DETAILED DESCRIPTION

(16) FIG. 1 generally shows a plasma electrode for a plasma arc torch, wherein an approximately hollow cylindrical electrode body 1 carries in the region of a flange 3 seals 2 whereby it is inserted in a sealing manner into a non-depicted housing. The exact manner of fastening is shown in EP 2082622B.

(17) According to FIG. 4, the electrode body 1 has a central internal bore 28 and forms at the front side thereof an approximately cylindrical electrode core holder 12 which is integrally connected to the remaining material.

(18) Inserted into the electrode core holder 12 is an electrode core 11 consisting, for example, of hafnium. In the example embodiment according to FIG. 1 the electrode core 11 extends through the entire electrode core holder 12, while in the example embodiment according to FIG. 4 the electrode core 11 is configured shorter.

(19) It is important in both embodiments according to FIGS. 1 and 4 that the electrode core holder 12 is preferably configured small in cross-section and otherwise cylindrical, in order to allow a good flow of the cooling medium over the surfaces thereof, as shown in FIG. 1.

(20) The rear end of the electrode core holder 12 according to FIG. 4 forms a face end stop surface 26 for a spacer means which is installed in the cooling tube 4.

(21) The cooling tube 4 in turn consists of a hollow cylindrical metal or plastic body, in the internal bore 34 (see FIG. 3) of which a cooling channel 9 is provided for the passage of a cooling medium which flows in the direction of arrow 10 into the internal bore 34.

(22) The cooling tube 4 has at the rear end thereof a screw thread 7 and furthermore a sealing device having a gasket 6, which is arranged in the region of the flange 5.

(23) Sealing by means of the gasket 6 is carried out in a manner not illustrated, such that a flows in the direction of arrow 17 from the cooling channel serving for the return flow 8 into an associated outlet 18 and is removed from there. Instead of a threaded connection, a plug-type connection can be provided.

(24) According to the invention it is now provided that a spacer disk 13 is disposed in the interior of the cooling tube 4, at an axial distance from the frontmost tip 16, the spacer disk 13 in the illustrated embodiment of FIG. 1 being formed integrally with the material of the cooling tube 4. The spacer disk 13 is produced together with the cooling tube during machining thereof.

(25) In FIG. 2, the spacer disk 13 is shown in a top view. It essentially comprises a center cross 19 which is integrally connected in terms of material to the material of the cooling tube 4 and comprises a multiplicity of passage openings 14 which are disposed in the intermediate space between the intersecting bars of the center cross 19.

(26) The center cross 19 forms a centrical stop surface 20, which is associated with the stop surface 26 of the electrode core holder 12 according to FIG. 4.

(27) In lieu of the passage openings 14 bounding each of the quadrants of the center cross, individual passage bores comprising one or more bores per quadrant can be provided.

(28) The cooling medium entering in the direction of arrow 10 into the supply cooling channel 9 accordingly flows through the passage openings 14 in the spacer disk 13 and is deflected at the front end of the electrode body 1 in the region of a reverse path 15 and then flows back on the outer circumference of the cooling tube 3 in the direction of arrow 17 via the cooling channel 8 disposed there as a return passage.

(29) The flow conditions are shown in detail in FIG. 3.

(30) It can be seen that in the reverse path 15, the cooling medium is deflected in the direction of arrow 21 and flows back on the outer circumference of the cooling tube 4 in the direction of arrow 22, and in the process, after about of the length of the cooling tube, encounters pressure vanes 23 disposed there.

(31) Because these pressure vanes 23 are disposed evenly distributed on the circumference of the cooling tube and are situated in the cooling channel 8, a pressure force 25 directed in the longitudinal direction of the cooling tube towards the rear against the threaded fastening device 7 thereof, is exerted onto this threaded mounting device. One, two or more pressure vanes can be present.

(32) FIG. 3 shows as a modified example embodiment the case where the pressure vanes 23 are not in the form of straight extension pieces, but are disposed tapered in the cooling channel 8. As a result of this taper, a spiral vortex flow is generated downstream of the pressure vanes 23, causing an additional rotational component to be exerted on the cooling tube 4 and this rotational component is directed such that the threaded connection to the screw thread 7 is solidified.

(33) FIG. 6 shows the front view of the pressure vanes 23a of straight design, which accordingly generate only a straight, axially directed pressure force 25 in the direction of arrow drawn in FIG. 3 in the direction towards the rear threaded connection to the screw thread 7.

(34) Conversely, if the pressure vanes 23a in FIG. 7 are tapered, a vortex flow 24 according to FIG. 3 is generated.

(35) FIG. 5 shows that pressure vanes 23, 23, 23b, 23c, 23d of any kind may also be disposed on the outer circumference of a ring 36. The ring 36 may be in the form of a plug-on ring which can be plugged or snapped onto the outer circumference of the cooling tube 4. FIG. 8 shows another embodiment of the ring 36, which is provided with an internal thread 37 which can be screwed onto an associated external thread on the cooling tube 4.

(36) FIG. 9 shows as a further embodiment propeller-shaped pressure vanes 23b which further intensify the vortex flow 24 and generate a torque 30 directed in closing direction 30 onto the threaded connection to the screw thread 7.

(37) FIG. 4 also shows that the electrode body 1 in turn carries at the rear end thereof a threaded fastening device 29, whereby it is screwed in a sealing manner into an associated casing part of the plasma arc torch. A plug-type or clamp-type connection can be provided instead.

(38) At the bore bottom 27 of the electrode body 1, the reverse path 15 is thus formed.

(39) FIGS. 10 and 11 show a releasable fastening device on the spacer disk 13, wherein individual spacer knobs 32 which are distributed evenly on the circumference are formed by displacement of material from the material of the cooling tube, and at a distance from which further locking nobs 33, e.g. as three locking knobs evenly distributed on the circumference may be formed, whereby a locking receptacle between the knobs 32, 33 for locking engagement of a spacer disk 13 is created which is pushed in in the direction of arrow 31.

(40) FIG. 11 shows as a modified embodiment that, instead of stop knobs 32, 33, an internal thread may be disposed at the same location in the cooling tube and the spacer disk 13 has a thread 35 on the outer circumference thereof, such that the spacer disk can be easily screwed with the external thread thereof into the internal thread of the cooling tube using a suitable tool, where it is thus fixed in place.

(41) It is not shown in the drawing that the spacer disk 13 may also be clipped into an undercut groove incorporated on the inner circumference of the cooling tube or screwed into an internal thread incorporated therein.

(42) It is also possible to incorporate a shoulder of reduced diameter on the inner circumference of the cooling tube and to move the spacer disk 13 with the outer circumference thereof in axial direction into engagement against this shoulder. The position of the spacer disk 13 at this shoulder can then be secured by means of a threaded ring screwed into the inner circumference, or by means of a snap ring which is snapped into a groove which is disposed in the axial direction in front of the shoulder holding the spacer disk.

(43) FIGS. 12 and 13 show a sectional view through the front end of the cooling tube at the height of the spacer disk 13 shown in FIG. 10. FIG. 12 shows that the spacer disk 13 in the simplest form thereof can also be in the form of a wire or rod 13a transversely extending through the bore of the cooling tube. The wire or rod 13a is inserted, soldered or press fit into mutually aligned bores 38 in the cooling tube 4. The rod or wire 13a may be composed of plastic or metal.

(44) FIG. 13 shows that also a plurality of intersecting wires or rods 13a may be inserted in the internal bore. Said parts can be snapped in place in an undercut groove on the inner circumference of the cooling tube. They can be connected to one another also in the middle region and form a cross which is locked or clamped into the undercut groove.

(45) TABLE-US-00001 Drawing Legend 1 electrode body 2 sealing device 3 flange 4 cooling tube 5 flange 6 gasket 7 screw thread 8 cooling channel (return flow) 9 cooling channel (supply flow) 10 direction of arrow 11 electrode core 12 electrode core holder 13 spacer disk or spacer 13a wires or rods 14 passage opening 15 reverse path 16 tip (of 4) 17 direction of arrow 18 outlet 19 center cross 20 stop surface 21 direction of arrow 22 direction of arrow 23 pressure vanes a, b 24 vortex flow 25 pressure force 26 stop surface 27 bore bottom 28 internal bore (of 1) 29 threaded connection 30 torque 31 direction of arrow 32 stop knob 33 locking knob 34 internal bore (of 4) 35 thread (of 13) 36 ring 37 internal thread 38 bore