Protective cap for a contact pipe in a welding torch in addition to a welding torch equipped with said cap

p0001The invention relates to a protective cap according to the preamble of claim 1. (See FIG <patcit id="pcit0001" dnum="WO9745227A"><text>WO-A-97 45227</text></patcit>).

p0002The invention further relates to a welding torch with at least two contact tubes enclosed by a common gas nozzle, each contact tube having a bore for guiding and contacting a supplied welding wire.

p0003In welding technology, the problem arises that welding probes are often produced during welding which adhere to the parts closest to the welding point, in particular to the contact tube. As a result, a large number of such deposits can lead to short circuits between individual parts. The problem of the adhesion of the welding spatter is increased by the use of electrically highly conductive materials such as, for example, copper or a copper alloy or brass or a measuring alloy which causes a heating of the material due to the current flow and thus the welding spatter very easily adhere to the contact tube.

p0004In particular, this problem occurs with two-wire or multi-wire welding burners, in which different controls or arrangements are implemented for the individual welding circuits, in which case the welding sprayers deposit and form a short circuit between the contact tubes which are to be as close as possible to one another That no separate control or regulation of the individual processes is possible.

p0005In order to avoid the adherence of welding sprays, the <patcit id="pcit0002" dnum="DE19904348A1"><text>DE 199 04 348 A1</text></patcit> A current contact nozzle or a contact tube for an arc welding torch, at least one or several different layers of one or more ceramic materials with a thickness of 0.1 to 0.7 mm being applied to one another on the surface of the contact tube, roughened at this location, at least at the wire exit side. These layers are electrically insulating and repellent against metal spatter. It is disadvantageous in this case that by means of such a coating of the contact tube an increased production effort is necessary and the service life of the contact nozzle is lengthened only insignificantly.

p0006Further is from the <patcit id="pcit0003" dnum="DE4426993C1"><text>DE 44 26 993 C1</text></patcit> A device for spraying an anti-stick agent against welding sprayers into the gas nozzle of a welding torch. The welding torch has an anti-stick container which is connected to a spray nozzle. It is disadvantageous in this case that in such a welding torch the size is substantially increased and retrofitting into existing welding torches is not possible.

p0007The <patcit id="pcit0004" dnum="GB1564077A"><text>GB 1 564 077 A</text></patcit> Describes a welding torch in which the contact nozzle is protected by a ceramic sleeve which is open in the direction of the welding location. However, such a nozzle can not protect the contact nozzle from welding spatter and thus increase its service life. The protective cap according to this document does not have a hole for the exit of the welding wire.

p0008The <patcit id="pcit0005" dnum="DE2920917A1"><text>DE 29 20 917 A1</text></patcit> Shows a contact nozzle for protective gas welding burners in which a ceramic insulation can be arranged between the gas pipe and the current-carrying contact nozzle. This insulating sleeve is used to prevent a short circuit between the contact nozzle and the gas pipe when the gas pipe touches the edges of a welding gap.

p0009The <patcit id="pcit0006" dnum="US5856647A"><text>"US 5 856 647 A</text></patcit> Describes a plasma welding torch in which a protective cap is arranged which protects the nozzle from welding spatter. In this case, the opening in the protective cap, which is not intended for guiding a welding wire in this construction, is relatively large so that weld spatter could enter the interior.

p0010Finally, the <patcit id="pcit0007" dnum="WO9532832A1"><text>WO 95/32832 A1</text></patcit> A contact nozzle for a welding torch in which the front tip is made of a more resistant material. The tip of the contact nozzle is fastened by screw connections. In the case of two-wire or multi-wire welding burners with two or more contact nozzles, a short circuit between the contact nozzles could not be prevented in this way due to adhering welding sprayers. Furthermore, the construction according to the<patcit id="pcit0008" dnum="WO9532832A1"><text>WO 95/32832 A1</text></patcit> A special construction of the contact tube which makes the use of commercially available contact tubes impossible.

p0011From the <patcit id="pcit0009" dnum="GB999509A"><text>GB 999 509A</text></patcit> A protective cap of the subject type is known, which is arranged above the contact tube of a welding torch with three welding wires. The hemispherical tip of the protective cap is made of or coated with a refractory material and is connected to the contact tube by means of a screw. The protective cap is relatively hard to fix and does not provide any protection against welding splashes between the contact tube and the gas nozzle, which can lead to short circuits.

p0012The <patcit id="pcit0010" dnum="FR2512717A"><text>FR 2 512 717 A</text></patcit> Shows a contact tube for a single-wire welding torch which is protected with a ceramic coating or a sleeve of ceramic in front of welding sprays and the high temperatures at the welding site, so that a longer operating time is possible. In this case, a protective part made of ceramic material is glued to the end face of the contact tubes, which protects the contact tube from excessive temperatures and welding spatter. The adhesive connection makes it difficult or impossible to replace the protective cap. The coating is disadvantageous because of the high production costs. Effective protection of two-wire or multi-wire welding burners is not described in this document.

p0013The <patcit id="pcit0011" dnum="WO9745227A1"><text>WO 97/45227 A1</text></patcit> Describes multi-wire welding burners, in which the welding wires are movable via separately controllable wire feeding devices.

p0014The object of the present invention is to substantially increase the service life of a contact tube or a welding torch with at least one such contact tube.

p0015The object according to the invention is achieved by a protective cap according to claim 1, wherein at least at least two openings for receiving at least two contact tubes and at least one further opening for accommodating further elements of the welding torch, in particular for accommodating a partial region of a burner body with the contact tubes fastened therein , And that fastening elements are arranged on an outer surface of the housing and are formed by at least one web, by means of which a clamping connection with a gas nozzle of the welding torch can be produced by plugging on the protective cap, whereby in the region of the gas nozzle, that is to say at the end of the burner body, And wherein the housing is provided with bores through which a gas fed by the welding torch can exit into the region between the gas nozzle and the protective cap. By the use of such a protective cap for two-wire or multi-wire welding torches with two or more contact tubes, these can be covered completely opposite the welding point and thus the adhesion of welding spatter can be prevented. This substantially increases the service life of such a two-wire or multi-wire welding torch. A further significant advantage is that by the use of such a protective cap, commercially available contact tubes can be used without reworking and thus the costs for this wearing part can be kept very low. A complex coating of the contact tubes, for example with a ceramic layer, is not necessary. Apart from the avoidance of welding spikes at the tip of the contact nozzle, short-circuits between the contact nozzles are effectively prevented by the present protective cap for two-wire or multi-wire welding torches. The corresponding arrangement of the holes in the housing of the protective cap for the welding wires guarantee a smooth conveying of the welding wire during the welding process. The present protective cap thus represents a cost-effective possibility for two-wire or multi-wire welding burners to effectively protect the contact tubes and thus to increase the operating time of the welding torch. Fastening elements are arranged on an outer surface of the housing which are formed by at least one web via which a clamping connection can be produced with a gas nozzle of the welding burner by plugging on the protective cap. As a result, the protective cap can be installed and removed quickly at the contact tubes or at the gas nozzle of the welding burner. The fastening element formed by the web represents a simple and effective realization possibility. By virtue of the at least one further opening for receiving further elements of the welding torch, all conductive elements of the welding torch are covered by the protective cap in the region of the gas nozzle. By means of the bores arranged on the housing of the protective cap, a gas supplied by the welding burner can escape into the region between the gas nozzle and the protective cap. These bores can be arranged for the most varied welding torches preferably corresponding to the gas outlet openings on the welding torch.

p0016Advantageously, the housing of the protective cap is formed from a material with low adhesion of metal sprayers, in particular welding sprayers. If, however, the adherence of weld spatter occurs, this does not significantly affect the welding process, since the material of the protective cap is electrically poor or nonconductive and thus no short circuits can occur between the contact nozzle and the gas nozzle or between the contact nozzles.

p0017Likewise, the housing of the protective cap can be coated with a material with low adhesion of metal sprayers, in particular welding sprayers.

p0018In this case, ceramics are particularly suitable as the material of the housing or the coating of the housing of the protective cap.

p0019According to a further feature of the invention, the bores on the housing are arranged radially circumferentially.

p0020The protective cap can also be designed in such a way that at least one contact tube is integrated in the housing so that a so-called sandwich component is formed.

p0021At the same time, at least one contact tube can be integrated or embedded over a partial region in the housing of the protective cap.

p0022The integrated contact tubes preferably consist of electrically conductive material, in particular of copper or a copper alloy, in order to enable the electrical connection to the welding wire.

p0023The object according to the invention is also achieved by means of a welding torch of the type indicated above, wherein at least a protective cap described above is arranged over a partial region of the contact tubes.

p0024Preferably, an opening is provided in the housing of the protective cap for accommodating the contact tubes and with the bores, which are at least one opening, wherein the bores run in alignment with the bores of the contact tubes in the case of contact tubes arranged in the protective cap so that the welding wires supplied Via the bores in the contact tubes and the bores of the protective cap to a welding point. In such a two-wire or multi-wire welding torch, the operating time is substantially increased by such a construction of the protective cap.

p0025The contact tubes preferably consist of electrically conductive material, in particular of copper or a copper alloy, to enable the electrical connection to the welding wires.

p0026The present invention will be explained in more detail with reference to the accompanying drawings, which show an embodiment of the invention.

p0027Therein:<dl id="dl0001" compact="compact"><dt>FIG</dt><dd>5 shows a schematic representation of a welding machine or a welding device;</dd><dt>FIG</dt><dd>4 is a perspective view of a protective cap, in a simplified schematic representation;</dd><dt>FIG</dt><dd>6 shows a further perspective view of the protective cap according to FIG <figref idrefs="f0002">FIG</figref>;</dd><dt>FIG</dt><dd>6 shows a front view of the protective cap according to FIG <figref idrefs="f0002">FIG</figref>;</dd><dt>FIG</dt><dd>7 a rear view of the protective cap according to FIG <figref idrefs="f0002">FIG</figref>;</dd><dt>FIG</dt><dd>FIG. 6 is a partial sectional side view of the protective cap arranged in a gas nozzle according to FIG <figref idrefs="f0002">FIG</figref>;</dd><dt>FIG</dt><dd>6 shows a sectional representation of the protective cap arranged in the gas nozzle according to FIG <figref idrefs="f0003">FIG</figref>;</dd><dt>FIG</dt><dd>4 is a perspective view, in simplified schematic representation, of an example of a protective cap, which does not fall within the scope of the claims.</dd><dt>FIG</dt><dd>6 shows a further perspective view of the protective cap according to FIG <figref idrefs="f0004">FIG</figref>;</dd><dt>FIG</dt><dd>6 a side view of the protective cap according to FIG <figref idrefs="f0004">FIG</figref>; and</dd><dt>FIG</dt><dd>3 shows a further example of a protective cap with contact tubes integrated therein, in a sectioned, schematic side view. This game is not covered by the scope of the claim.</dd></dl>

p0028In <figref idrefs="f0001">FIG</figref> A welding machine 1 or a welding machine is shown for various welding methods, such as MIG / MAG welding or TIG welding or electrode welding, double-wire / tandem welding, plasma or soldering processes, etc. It is, of course, possible that the solution according to the invention can be used with a current source or a welding current source.

p0029The welding device 1 comprises a current source 2 with a power component 3, a control device 4 and a switching element 5 assigned to the power component 3 or the control device 4. The switching element 5 or the control device 4 is connected to a control valve 6 which is arranged in a supply line 7 for A gas 8, in particular a protective gas, such as CO₂, Helium or argon and the like, is arranged between a gas accumulator 9 and a welding torch 10.

p0030In addition, a wire feed device 11, which is customary for MIG / MAG welding, can be controlled via the control device 4, wherein an additional material or a welding wire 13 is fed via a supply line 12 from a supply drum 14 into the region of the welding torch 10. It is, of course, possible for the wire feed device 11, as is known from the prior art, to be integrated in the welding device 1, in particular in the basic housing, and not as shown in FIG<figref idrefs="f0001">FIG</figref> , Is designed as an additional device.

p0031It is also possible for the wire feed device 11 to feed the welding wire 13 or the additional material outside the welding torch 10 to the process site or weld, for which purpose a non-melting electrode is preferably arranged in the welding torch 10, as is customary in WIG / TIG welding Is.

p0032The current for building an arc 15 between the melting electrode 13 and the welding wire 13 and a workpiece 16 is fed to the welding torch 10 from the power part 3 of the current source 2 via a welding line 17, the workpiece 16, which is to be welded, Is also connected to the welding device 1, in particular to the current source 2, via a further welding line 18, and thus a circuit can be constructed for the arc welding process or the plasma arc for the process at the welding site.

p0033In order to cool the welding torch 10, the welding torch 10 can be connected to a liquid container, in particular a water container 21, by way of a cooling circuit 19, whereby the cooling circuit 19, in particular a liquid arranged in the water container 21, Is started and thus cooling of the welding torch 10 can be effected.

p0034The welding device 1 further has an input and / or output device 22, via which the most diverse welding parameters, operating modes or welding programs of the welding device 1 can be set or called. The welding parameters, operating modes or welding programs set via the input and / or output device 22 are forwarded to the control device 4, and the individual components of the welding device or the welding device 1 are subsequently controlled by the latter.

p0035Furthermore, in the exemplary embodiment shown, the welding torch 10 is connected to the welding device 1 or the welding system via a hose pack 23. In the hose pack 23, the individual lines from the welding device 1 to the welding torch 10 are arranged. The hose pack 23 is connected to the welding torch 10 via a coupling device 24, whereas the individual lines in the hose pack 23 are connected to the individual contacts of the welding device 1 via connecting sockets or plug connections. In order to ensure a corresponding strain relief of the hose pack 23, the hose pack 23 is connected to a housing 26 of the welding device 1 via a strain relief device 25. It is, of course, possible that the coupling device 24 can also be used for the connection to the welding device 1.

p0036It is to be mentioned in principle that not all previously named components have to be used or used for the different welding methods or welding devices 1, such as, for example, TIG devices or MIG / MAG devices or plasma devices. If, for example, a multi-wire welding process, in particular a double-wire welding process, is carried out, a further welding device 1 is preferably used, the two welding devices 1 being then connected to a common welding torch 10, as is known from the prior art. For this purpose, the two welding devices 1 are connected via control lines, so that a corresponding synchronization of the two welding devices 1 can take place. It is, of course, possible for only a single welding device 1 to be used, which is then designed in such a way that two or more independent circuits can be constructed in order to achieve independent control and regulation of the individual welding processes.

p0037In the <figref idrefs="f0002">FIGS. 2 to 5</figref> An embodiment of a protective cap 27 is shown which is arranged in a welding torch 10 with at least two contact tubes 40, 41 (see FIG <figref idrefs="f0005">FIG</figref>) Is used. The contact tubes 40, 41 are enclosed by a common gas nozzle 28 and each have a bore for guiding and contacting a welding wire 13 supplied. The contact tube 40, 41, which effects the current transfer to the welding wire 13, preferably consists of electrically conductive material, in particular of copper or a copper alloy, or is provided with corresponding contacts. The protective cap 27 is inserted or arranged over the contact tubes 40, 41 or over a partial region of the contact tubes 40, 41. For this purpose, the protective cap 10 has two openings 29, 30 for receiving the contact tubes 40, 41. Furthermore, bores 31, 32 are arranged in the protective cap 27, which are connected to the openings 29, 30 for receiving the contact tubes 40, 41. The bores 31, 32 are arranged in the protective cap 27 or in a housing 33 of the protective cap 27 in such a way that, when the contact tubes 40, 41 are inserted, they run in alignment with the bores of the contact tubes 40, 41 so that a welding wire 13 is fed Can exit through the bores in the contact tube 40, 41 and the bores 31, 32 in the protective cap 27 to a welding location. The protective cap 27 is designed such that a separate opening 29, 30 and bores 31, 32 are arranged in the housing 33 of the protective cap 27 for each contact tube which is to be accommodated, when used in a multi-wire welding torch, in particular in a double-wire welding torch 10. A more exact positioning for the aligned transition between the bore of the contact tube and the bore 31, 32 on the protective cap 27 can thus be provided so that smooth wire conveyance can be ensured.

p0038The protective cap 27, in particular the housing 33 of the protective cap 27, is formed from a poorly electrically conductive material with poor adhesive properties of metal sprayers, in particular welding sprayers. The housing 33 is preferably formed from ceramic or from materials coated with ceramic. Through the use of an electrically non-conductive material, it is possible for the protective cap 27 to be inserted over several contact tubes 40, 41 without the protective cap 27 forming a short circuit between the individual contact tubes 40, 41. By completely closing the contact tubes 40, 41 through the protective cap 27 in the end region, ie, in the region of the welding location, it is also advantageously achieved that simultaneously the interspaces between the individual contact tubes 40, 41 are covered and thus the accumulation of welding sprayers in These intermediate spaces can be prevented. If, as is known from the prior art, a contact tube 40, 41 with a coated ceramic surface were used, the welding sprayers would gather between the contact tubes 40, 41 in the case of a multi-wire or double-wire welding torch And thus lead to a short circuit. Furthermore, fastening elements 35 can be arranged on an outer surface 34 of the housing 33 of the protective cap 27, via which a clamping or screw connection with the gas nozzle 28 can be produced. For example, the fastening elements 35 can be formed by at least one web 36, via which the protective cap 27 is connected to the gas nozzle 28 and is held on the welding burner 10 when the gas nozzle 28 is plugged on or fixed. This is shown schematically in the<figref idrefs="f0003">FIGS. 6 and 7</figref> shown. It is, of course, possible for the protective cap 27 to be attached to the welding torch 10 in various ways.

p0039The protective cap 27 can have a further opening 37 for receiving further elements of the welding torch 10, in particular a partial region of a burner body (not shown) with the contact tubes fastened therein. Thus, in the region of the gas nozzle 28, that is to say at the end of a burner body, all the conductive elements of the welding burner 10 are covered by the protective cap 27. The protective cap 27 is therefore inserted over all the electrically conductive parts of the welding torch 10, so that a short circuit between an electrically conductive part of the welding torch 10 and the gas nozzle 28 can never occur due to welding splatters possibly adhering in the gas nozzle 28. As a result of such a construction of the protective cap 27, it is now necessary for further bores 38 to be arranged on the protective cap 27, by means of which the supplied gas 8 can escape from the welding burner 10 into the interior of the gas nozzle 28. These bores 38 can be arranged for the most different welding torches 10 correspondingly to the gas outlet openings on the welding torch 10 in the housing 33 of the protective cap 27. In the illustrated exemplary embodiment, bores 38 are arranged radially around the housing 33, via which the gas 8 supplied by the welding burner 10 can escape into the region between the gas nozzle 28 and the protective cap 27.

p0040In the <figref idrefs="f0004">FIGS. 8 to 10</figref> A non-inventive example of a protective cap 27 is shown. In contrast to the embodiment variant according to FIGS<figref idrefs="f0002 f0003">FIGS. 2 to 7</figref> The protective cap 27 no longer accommodates the entire contact tubes 40, 41, but is arranged only in the end region of the contact tubes 40, 41, ie in the region of the welding site. The protective cap 27 thus forms a cover for the ends of the contact tubes 40, 41.

p0041According to the non-inventive form according to FIG <figref idrefs="f0005">FIG</figref> The protective cap 27 and the contact tubes 40, 41 can also form a common sandwich component 39. During the production of the protective cap 27, the commercially available contact tubes 40, 41 are embedded in the housing 33 made of ceramic or with a ceramic coating of the protective cap 27. The protective cap 27 with the integrated contact tubes 40, 41 is then inserted into the welding torch 10, or attached thereto, so that an electrical connection with the contact tubes 40, 41 is provided. In such a configuration, it is achieved that the protective cap 27 and the contact tubes 40, 41 can be attached or removed in one working step. This makes a very fast and easy exchange possible. The essential difference of the sandwich construction according to<figref idrefs="f0005">FIG</figref> Compared with the prior art, is that commercially available contact tubes 40, 41 can be used without post-processing, which are embedded only in the production of the protective cap 27. On the other hand, complicated coating methods for applying a ceramic layer to the contact tubes 40, 41 are used in the known designs, resulting in very high production costs. On the other hand, the production costs for a sandwich component 39 can be corresponding<figref idrefs="f0005">FIG</figref> Can be kept very low.

p0042The illustrated exemplary embodiments of the protective cap 27 are, of course, not limited to the illustrated forms but can be designed as desired. A further embodiment for a protective cap 27 with at least two contact tubes 40, 41 could also be effected in such a way that the protective cap 27 is formed from a plurality of parts, in particular two parts, the opening 29, 30 for the contact tubes 40, Is arranged. In this case, the contact tubes 40, 41 are inserted into a part of the protective cap 27, and the second part of the protective cap 27 is then placed thereon so that the tube tubes 40, 41 are integrated completely inside the protective cap 27. An end region of the contact tubes 40, 41 projects out of the protective cap 27 so that the contact tubes 40, 41 can be attached to the welding torch 10 and a corresponding electrical connection from the welding torch 10 to the contact tubes 40, 41 can be achieved. In this way, the protective cap 27 can be fastened directly to the contact tubes 40, 41 so that, when the contact tubes 40, 41 are worn, these can be easily exchanged.

p0043If, on the other hand, the contact tubes 40, 41 are completely integrated in the protective cap 27, the provision of a power supply to the contact tubes 40, 41 is necessary. For example, contact elements may be integrated in the protective cap 27, which in turn provide an electrical connection to the contact tubes 40, 41 and, on the other hand, an electrical connection to the welding torch 10 (not shown).