WELDING OR CUTTING TOOL

Abstract

A welding or cutting tool for welding or cutting electrically conductive workpieces includes a nozzle arranged on a tool tip for discharging a welding or cutting beam and a nozzle cap which at least partly surrounds the nozzle, is open towards the tool tip, and has an electrode that forms a capacitance with the respective workpiece and an insulating element that electrically insulates the electrode from the other components of the tool. The electrode consists of a first electrically conductive ceramic material and is formed integrally with the insulating element, which consists of a second electrically insulating ceramic material.

Claims

1. Welding or cutting tool for welding or cutting electrically conductive work pieces, having a nozzle (18) disposed at a tool tip (18), for exit of a welding or cutting jet, and having a nozzle cap (28) that encloses the nozzle (18), at least in part, and is open toward the tool tip (16), which cap has an electrode (32) that forms a capacitance with the respective work piece, and which cap has an insulating element (34) that electrically insulates the electrode (32) relative to the further components of the tool, therein the electrode (32) comprises a first, electrically conductive ceramic material, and is Configured in one piece with the insulating element (34), which comprises a second, electrically insulating ceramic material.

2. Too according to claim 1, wherein the first ceramic material is titanium nitride or ceramic having titanium nitride.

3. Tool according to claim 1, wherein the second ceramic material is aluminum oxide.

4. Tool according to claim 1, wherein the nozzle cap (28) has a contact element (36) that connects the electrode. (32) with an electrical connector (44) of evaluation electronics (48), in electrically conductive manner.

5. Tool according to claim 4, wherein the contact element (36) comprises the first ceramic material.

6. Tool according to claim 4, wherein the contact element (36) is configured as a film strip having a thickness of maximally 0.2 mm, preferably of maximally 0.1 mm.

7. Tool according to claim 4, wherein the contact element (36) is embedded into the insulating element (34).

8. Tool according to claim 4, wherein the contact element (36) extends over a step (42) on the insulating element (34) that runs transverse to a longitudinal tool axis (40), and there contacts the connector (44) of the evaluation electronics (48).

9. Tool according to claim 8, wherein the contact element (36) projects from the insulating element (34) at the step (42), and there is bent to produce planar contact with the step (42).

10. Tool according to claim 4, wherein the contact element (36) is disposed on an inner surface (38) of the insulating element (34) that faces the nozzle (18).

11. Tool according to claim 1, wherein the electrode (32) has an outer surface, facing away from the nozzle. (18), in the shape of a spherical calotte having an exit opening (30) disposed in the center.

12. Tool according to claim 11, wherein the electrode (32) has the shape of a segment of a spherical shell having an exit opening (30) disposed in the center.

13. Method for the production of a nozzle cap (28) for a welding or cutting tool (10) according to claim 1, wherein in a two-component ceramic injection-molding method, the raw material for the first ceramic material, which forms the electrode (32), is introduced into an injection mold in a first method step, and the raw material for the second ceramic material, which forms the insulating element (34) is introduced into the injection mold in a second method step, and wherein the semi-finished product obtained in this manner is then removed from the injection mold and conducted to a firing process

14. Method for the production of a nozzle cap (28) for a welding or cutting tool (10) according to claim 1, wherein the raw material for the ceramic material that forms the electrode (32) is introduced into a first injection mold, and the raw material for the second ceramic material, which forms the insulating element (34), is introduced into a second injection mold, and wherein the semi-finished products obtained in this manner are removed from the injection molds and joined together in a common firing process.

15. Method according to claim 13, wherein the raw material for the first ceramic material that forms the contact element (36) is introduced into: the: respective injection mold before removal of the semi-finished product or of the semi-finished insulating element from the injection mold, in a further method step.

Description

[0010] In the following, the invention will be explained using an exemplary embodiment shown schematically in the drawing. The figures show:

[0011] FIG. 1 a cutting torch in longitudinal section, and

[0012] FIG. 2 an enlarged representation of the front region of the cutting torch according to FIG. 1, which region has the torch tip, in longitudinal section.

[0013] The cutting torch 10 shown in FIG. 1 has a torch body 12 that extends, in a longitudinal direction, from a connector part 14 all the way to a torch nozzle 18 that forms the torch tip 16, which nozzle is attached to the body. The torch body 12 has gas feed lines 20 that extend, in the longitudinal direction, from the connector part 14 to the torch nozzle 18, indicated only with broken lines in FIG. 1, and can be connected with a gas supply device by way of connector flanges 22. A mantle tube 24 composed of metal is pushed onto the torch body 12, which tube encloses the body all around over a major portion of its length, and ends at a distance from the connector part 14 and also at a distance from the torch nozzle 18. A nozzle cap 28 is attached to the mantle tube 24 by means of a cap nut 26, which cap encloses the nozzle-side end of the torch body 12 as well as a major portion of the torch nozzle 18 all around, and has a central exit opening 30, from which the tip of the torch nozzle 18, which tip forms the torch tip 16, projects for a short distance.

[0014] The nozzle cap 28 (FIG. 2) has a ceramic basic body that is produced, in one piece, from two ceramic materials. In this regard, an electrode 32 having the shape of a segment of a spherical shell and provided with the exit opening 30 is produced from an electrically conductive first ceramic material, particularly from titanium nitride or from a mixture of titanium nitride and aluminum oxide, while an insulating element 34, attached to the mantle tube 24 by means of the cap nut 26 and connected in one piece with the electrode 32, is produced from an electrically insulating second ceramic material, in the present case from aluminum oxide. A contact element 36, also consisting of the first ceramic material, runs from the electrode 32, by way of an inner surface 38 of the insulating element 34, which surface faces the torch nozzle 18, all the way to a step 42 of the insulating element 34, which step extends perpendicular to the longitudinal torch axis 40, where the element is contacted by means of an electrical connector 44 composed of metal. Alternatively, however, it is also possible to embed the contact element 36 into the insulating element 34, so that it is not exposed to any environmental influences. Then, similar to what is shown in FIG. 2, it can project out of the insulating element 34 at the step 42 and can be bent there to produce the contact with the electrical connector 44. At the other end, it is possible to either embed the contact element 34 into the electrode 32, or, alternatively, to also bend a section that projects out of the insulating element 34, so that the section lies against the electrode 32. This embodiment is particularly advantageous if the contact element 36 is configured as a thin film. A connector cable 46 extends from the connector 44 to an electronic evaluation unit 48 disposed in the mantle tube 24, at its end facing the connector part 14. The electronic evaluation unit 48 has a microprocessor 48a and other active components, such as discriminators, bus drivers, operation amplifiers or varactor diodes, for example, as well as passive electrical components 48b, which, together with the electrode 32 forming the capacitance, form an electrical oscillating circuit, the frequency of which is dependent on the capacitance and thereby on the distance of the electrode 32 from an electrically conductive work piece to be worked on. In this way, the distance from the work piece can be regulated by way of frequency measurement and evaluation by means of the microprocessor 48a.

[0015] The components 48a, 48b of the electronic evaluation unit 48 are disposed on at least one circuit board, in each instance, which is in contact with the torch body 12 and thereby is cooled by the gases supplied to the torch nozzle 18 by way of the gas feed lines 20, in general acetylene or propane and oxygen. The passive electrical components 48b, which are less temperature-sensitive than the microprocessor 48a or the active components, are disposed closer to the torch tip 16. The placement of the electronic evaluation unit 48 on the torch body 12 allows a simple connection with a distance regulation device, by means of a standard plug 50, which is disposed on the mantle tube 24 in the exemplary embodiment shown. Furthermore, a sensor 52, which serves for measuring the temperature and/or the structure-born sound in the torch body 12 and thereby detects any flashback at an early point in time and then interrupts the gas feed, which could destroy the cutting torch 10, as well as a high-tension generator 54 that serves for igniting the cutting torch 10 are disposed in the mantle tube 24. In the exemplary embodiment shown, the entire evaluation unit 48 is disposed in the mantle tube 24. However, it is also possible to dispose the microprocessor 48a above the mantle tube 24, on the torch body 12.

[0016] In the exemplary embodiment shown, a gap is disposed between the torch nozzle 18 and the electrode 32, in the region of the exit opening 30. However, it is also possible to fill the gap by means of an insulating material, and, in particular, to dispose the insulating element 34 to lie against the torch nozzle 18.

[0017] In summary, the following should be stated: The invention relates to a welding or cutting tool 10 for welding or cutting electrically conductive work pieces, having a nozzle 18 disposed at a tool tip 16, for exit of a welding or cutting jet, and having a nozzle cap 28 that encloses the nozzle 18, at least in part, and is open toward the tool tip 16, which cap has an electrode 32 that forms a capacitance with the respective work piece, and which cap has an insulating element 34 that electrically insulates the electrode 32 relative to the further components of the tool. According to the invention, it is provided that the electrode 32 consists of a first, electrically conductive ceramic material, and is configured in one piece with the insulating element 34, which consists of a second, electrically insulating ceramic material.