METHOD AND TRACKING GAS NOZZLE FOR FLOWING INTO A WELDING AREA OF A WORKPIECE

Description

[0001] The invention relates to a method for flowing at least one fluid over a welding area of ​​a workpiece along a welding path during a welding process, wherein the at least one fluid is flowed onto the welding area via at least one inlet and a plurality of channels with openings.

[0002] The invention further relates to a carrier gas nozzle for flowing at least one fluid over a welding area of ​​a workpiece along a welding path during a welding process, comprising a housing, at least one inlet for the at least one fluid and a plurality of channels with openings through which the at least one fluid flows onto the welding area, the channels with the openings being divided into at least two sectors, with at least one inlet for at least one fluid, which sectors are designed for the individual regulation of at least one flow parameter of the at least one fluid of each sector, wherein the at least two sectors are arranged depending on the geometry of the welding path and / or the geometry of the workpiece.

[0003] In most welding processes, a shielding gas is used to increase the stability of the welding process. This shielding gas is supplied via the gas nozzle to protect the arc. This shielding gas is also referred to as the primary shielding gas. To protect the trailing molten metal from air ingress and oxidation by oxygen, particularly in build-up welding and the so-called Arc-DED (Arc-Direct Energy Deposition) process, trailing gas nozzles of the type presented here are sometimes used. Additional shielding gas flows over the welding area through these nozzles to prevent the molten material from reacting with the oxygen in the surrounding air and to improve the weld quality. The shielding gas used with such trailing gas nozzles is also referred to as the secondary shielding gas. This is particularly important when machining workpieces made of alloyed steels, aluminum alloys, or titanium, etc.The use of a secondary shielding gas is necessary to achieve good welding results, as these materials react strongly with oxygen. For example, titanium oxidizes at temperatures above 300°C due to its high affinity for oxygen, which is why a protective atmosphere is required. Argon, for example, is used for this purpose and is also frequently used as the primary shielding gas to protect the arc during the welding process. The term "during the welding process" naturally also includes the phases before the welding process or before the arc is ignited, the so-called pre-run, during which a flow of air can be applied to prevent oxidation before welding begins, the phases after the welding process, the so-called post-run, during which the workpiece cools down, as well as any breaks between individual welding phases.

[0004] For smaller components made of the above-mentioned materials, the welding process can also be carried out in chambers to protect the weld seam or the welding area from air ingress and oxidation. However, welding in a chamber is very complex and also involves a very high consumption of shielding gas. Furthermore, welding larger workpieces, such as aircraft components, in chambers is either not possible or involves a very high level of effort.

[0005] The secondary shielding gas is applied in a suitable manner to the downstream welding area via trailing gas nozzles until the workpiece or the welding area has cooled below the temperature at which a reaction of the respective material with oxygen takes place. For example, WO 2020 / 234329 A1 describes a trailing gas nozzle which extends through a plurality of parallel gas channels, each with a height corresponding to at least six times the hydraulic diameter. This allows optimal flow and shielding gas distribution to be achieved and laminarization of the shielding gas flow within the gas channels to be achieved with relatively low shielding gas consumption. Thus, the welding area covered by the trailing gas nozzle is optimally protected from air ingress, resulting in a weld seam or a workpiece surface with optimal properties and the highest quality.

[0006] CN 106112230 A (disclosing the preamble of claims 1 and 9) describes a welding device in which devices for specifically flowing shielding gas to the welding point on both sides of the welding path are provided separately from the welding torch. Since the shielding gas devices are arranged separately from the welding torch, handling is increased. Measures to reduce shielding gas consumption are not mentioned.

[0007] US 2019 / 0001437 A1 discloses a device for cladding welding for flowing shielding gas to the weld site. The shielding gas is flowed to the melt via a series of appropriately arranged nozzles in a complex manner. Apart from the complex design, this prior art does not mention any measures to reduce shielding gas consumption.

[0008] Finally, JP H0871779 A discloses a special design of a laser welding device for pipe welding with several nozzles for flowing the welding point and the surrounding area with one and the same shielding gas.

[0009] In addition to a shielding gas, the welding area can also be exposed to a liquid or a mixture of a gas and a liquid to protect the welding area from oxygen and, if necessary, to cool it. Therefore, the term "fluid" is used below to encompass gases, liquids, and mixtures of gases and liquids.

[0010] A disadvantage of previous methods and carrier gas nozzles for supplying at least one fluid, particularly a shielding gas, to a welding area of ​​a workpiece along a welding path is the high consumption of the fluids used to protect or cool the welding area and the associated high costs. Shielding gases, such as argon, which are intended to prevent oxidation of the workpiece surface, are relatively expensive.

[0011] The object of the present invention is to provide the above-mentioned method and a trailing gas nozzle for flowing at least one fluid over a welding area of ​​a workpiece along a welding path, which minimizes the consumption of fluid for protecting and cooling the welding area and thus keeps costs low. The welding area should nevertheless be optimally protected from air ingress, resulting in the highest possible welding quality. The disadvantages of known methods and trailing gas nozzles of the present type should be avoided or at least reduced.

[0012] The object of the invention is achieved by an above-mentioned method for flowing a welding area of ​​a workpiece, wherein the openings of the channels are divided into at least two sectors, and at least one flow parameter of the at least one fluid of each sector is individually controlled, wherein at least one flow parameter of at least one fluid of at least one sector is controlled as a function of the geometry of the welding path and / or as a function of the geometry of the workpiece, see claim 1. By dividing the flow of the fluid, in particular a shielding gas or a cooling liquid, over the welding area of ​​the workpiece into sectors and by regulating the flow parameters of the fluid of each sector individually and as a function of the geometry of the welding path and / or as a function of the geometry of the workpiece, the at least one fluid can be used in a more targeted manner and thus the consumption of fluid can be significantly reduced.In contrast to conventional methods, in which the entire welding area of ​​the workpiece covered by the entraining gas nozzle is exposed to fluid, with the method according to the invention the flow of fluid to the welding area of ​​the workpiece can be regulated sector by sector and depending on the geometry of the welding path and / or depending on the geometry of the workpiece, thus only using the amount of fluid necessary to prevent oxidation or cooling of the workpiece surface. If the welding path is straight, the sector of the entraining gas nozzle covering the straight welding path during the manufacturing process is activated, and the largest amount of fluid flows onto the surface of the workpiece in this sector. If the welding path runs in a curve or corner, other sectors are controlled.The data on the geometry of the weld path is known to the welding device and must be transmitted to the device for controlling the flow parameters of the at least one fluid before the welding process is carried out. For example, the data from the welding robot can be used for this purpose. Since the geometry of the workpiece to be manufactured also has a significant influence on the temperature profile of the workpiece during the welding process, it is also advantageous to take this into account when controlling the flow parameters of the at least one fluid in each sector. A cooling fluid can also be used as the fluid, which allows for faster cooling and also allows the temperature of the workpiece material to fall below a certain level, thus reducing the consumption of the required shielding gas.A cooling liquid, preferably water, can be used as the cooling fluid, whereby the type of cooling liquid can be adapted to the material of the workpiece. When the cooling liquid evaporates, the resulting gas can also have a protective function for the surface of the workpiece. Furthermore, a more rapid reduction of the workpiece temperature below the temperature at which a reaction with the atmospheric oxygen takes place can be achieved. This results in higher weld quality due to optimal formation of the workpiece's microstructure. Due to the targeted control of the flow parameters of the fluid, specific temperature-time cooling profiles can be set for a desired cooling and thus a specific microstructure. For example, a so-called Widmannstätten microstructure can be achieved in this way, which is required in aircraft construction.Flow parameters are understood to be parameters that affect the flow of the fluid, in particular the flow rate, flow volume, or flow velocity of the protective gas, the cooling liquid, or a mixture of gas and liquid. According to the invention, the control of the flow parameters of at least one fluid in each sector is achieved relatively simply by sector-by-sector control using valves or flow regulators in supply lines, thus achieving relatively low effort.

[0013] If, in addition to the flow parameter of the at least one fluid, at least one property of the at least one fluid is also individually controlled, further advantages can be achieved. The term "property of the fluid" includes, for example, the type of fluid, the temperature of the fluid, or the composition of the fluid, for example, the composition of a mixture of several gases or the composition of a mixture of a gas and a liquid. If the properties of the at least one fluid in each sector are also individually controlled, the protection and cooling of the welding area of ​​the workpiece can be even more precisely tailored to the respective manufacturing process, and fluid consumption can be reduced or welding quality can be further improved.

[0014] If at least one flow parameter and / or at least one property of the at least one fluid in each sector is individually controlled depending on at least one temperature of the welding area of ​​the workpiece, the fluid consumption can be adapted even better to the actual conditions. In particular, if the temperature of the workpiece material falls below a certain level, the fluid flow can be omitted or the type of fluid can be changed, thereby saving further costs. For example, the temperature of titanium is 300°C, above which temperature the material must be protected with inert gases such as argon to prevent oxidation. Below this temperature, another gas such as compressed air, carbon dioxide, nitrogen or a liquid such as water can be used to cool the temperature of the welding area even further.Since compressed air, carbon dioxide, nitrogen, and water are significantly cheaper than argon, consumable costs can be significantly reduced. Furthermore, the use of water, for example, allows for faster cooling of the component when the oxidation temperature is reached. This also allows for shorter production times.

[0015] The at least one temperature of the welding area of ​​the workpiece can be measured with at least one temperature sensor in order to be able to regulate the flow parameters and / or properties of the at least one fluid in each sector depending on the temperature. The term "temperature sensor" encompasses all possible contact-based and contactless sensors, such as thermocouples, semiconductor elements (thermistors, PTC thermistors), pyroelectric sensors, mechanical sensors (strain gauges), magnetic temperature sensors, and even optical temperature sensors and thermal imaging cameras.

[0016] In addition to or alongside a physical temperature measurement, at least one temperature of the workpiece's welding area can also be estimated through simulation or parameter calculation. With the help of suitable software applications, the temperature profile of a replica of the workpiece during production can be determined and estimated virtually or computationally, and the control of the flow parameters and / or properties of the at least one fluid in each sector can be adjusted and controlled depending on this simulated temperature. Control parameters can also be determined through appropriate measurement or scanning of finished workpieces, for example, using optical methods.

[0017] Finally, at least one temperature of the workpiece's welding area can also be determined using the energy introduced into the workpiece during the welding process. In this indirect determination or estimation of the workpiece's temperature, the energy introduced is measured via the welding current and welding voltage, and the approximate temperature is determined from this. In particular, the geometry of the workpiece to be manufactured or machined, as well as the quantity and material of the welding material used, are also taken into account. While this method is not as accurate as physical temperature measurement, it does not require dedicated sensors or simulation processes.

[0018] Advantageously, if a predetermined limit temperature is undershot or exceeded, at least one flow parameter and / or at least one property of the at least one fluid in at least one sector is changed. In this way, limit values ​​for the temperature can be defined below or above which certain flow parameters and certain properties apply to the fluids, which properties are then adjusted depending on the temperature. For example, depending on the temperature of a workpiece material, the type of protective gas used as the fluid can be changed (below the so-called dissociation temperature of the inert gas used - e.g. argon - a more favorable non-inert gas - e.g. carbon dioxide CO2 - can be used). Likewise, the volume flow of the fluid used can be changed or regulated depending on the temperature profile on the workpiece or by defining at least one limit temperature.

[0019] Likewise, at least one flow parameter and / or at least one property of the at least one fluid in each sector can be individually controlled depending on a predefined temperature-time-cooling profile of the workpiece. This allows the formation of the workpiece's microstructure to be even more precisely adjusted and its design, type, and fineness to be influenced.

[0020] According to a further feature of the invention, at least one property of at least one fluid in at least one sector is controlled as a function of the geometry of the welding path and / or as a function of the geometry of the workpiece. This allows the fluid consumption to be further adapted sector by sector to the course of the welding path and the geometry of the workpiece. If the welding path is straight, the sector of the carrier gas nozzle covering the straight welding path during the manufacturing process is activated and the largest amount of fluid flows onto the surface of the workpiece in this sector. If the welding path runs in a curve or corner, other sectors are controlled. Since the geometry of the workpiece to be manufactured also has a major influence on the temperature profile of the workpiece during the welding process, it is advantageous to take the property of the at least one fluid in each sector into account when controlling it.

[0021] At least one flow parameter and / or at least one property of at least one fluid in at least one sector can also be controlled depending on the welding process. An arc welding process with low heat input, such as a CMT (Cold Metal Transfer) process, can be set, so air, for example, is sufficient as a fluid. Likewise, an arc welding process with a high heat input, such as a pulse welding process, can be set, which requires more intense cooling.

[0022] The object of the invention is also achieved by an above-mentioned entraining gas nozzle in which separate valves or separate flow regulators are provided for the at least one fluid in each sector, and a control system is provided with which the control of the at least one flow parameter of the at least one fluid in each sector takes place through sector-by-sector control by means of the valves or flow regulators in supply lines, so that at least one flow parameter of at least one fluid in at least one sector can be individually controlled depending on the geometry of the welding track and / or depending on the geometry of the workpiece, see claim 9. The channels and openings of the entraining gas nozzle are therefore divided into several sectors, which enables individual control of the flow parameters of the at least one fluid in each sector depending on the geometry of the welding track and / or depending on the geometry of the workpiece.The individual control is formed by individual inlets for at least one fluid for each sector or individual valves in inlet lines or intermediate lines which feed the channels of the sectors with the fluid.

[0023] Especially when the carrier gas nozzle is manufactured using a 3D printing process, this division of the channels into multiple sectors, as well as the necessary channels and inlets, can be produced relatively easily and cost-effectively. For further advantages, please refer to the above description of the process.

[0024] The sectors can be constructed as interconnectable modules. This modular design of the carrier gas nozzle achieves greater flexibility. Carrier gas nozzles suitable for specific manufacturing processes can be constructed by connecting the modules accordingly, creating a desired number and arrangement of sectors. The modules can be screwed together, for example, or connected without tools using snap-in connections. Permanent welded, soldered, or adhesive connections are also conceivable.

[0025] Depending on the application, the sectors can be arranged symmetrically, for example, circularly symmetrically, or asymmetrically. The number and arrangement of the sectors of the trailing gas nozzle will be adapted to the geometry and path of the weld path, the geometry of the workpiece, and the materials used. For materials that are particularly sensitive to oxidation, the trailing gas nozzle will also need to be larger, as the workpiece needs to be protected from air and cooled for a longer period before the material solidifies and there is no longer any risk of quality loss.

[0026] If at least one temperature sensor for measuring at least one temperature of the welding area of ​​the workpiece is provided on the carrier gas nozzle, the control of the flow parameters and properties of the at least one fluid can be further improved.

[0027] The at least one temperature sensor can be arranged in a suitable manner between the openings of the channels. The at least one temperature sensor is connected to the control device, for example, the control device of the welding power source, via appropriate lines. A wireless connection is also conceivable, with corresponding transmitting devices being arranged on the carrier gas nozzle, which transmits the signals from the temperature sensors to the respective devices.

[0028] If at least one cooling fluid line with at least one orifice for applying a cooling fluid to the welding area of ​​the workpiece is provided, in addition to the fluid flowing over the workpiece, faster cooling and even lowering of the critical temperature of the workpiece material can be achieved, thus further reducing the consumption of the more expensive shielding gases required above critical temperatures. A cooling liquid, preferably water, is used as the cooling fluid.

[0029] When using a cooling liquid, it is advantageous if a nozzle, in particular an atomizing nozzle, flat nozzle, conical nozzle, or the like, is arranged at at least one opening. This allows the cooling liquid to be applied to the hot surface of the workpiece in a particularly suitable manner and cool it.

[0030] If a preferably pivoting device is provided for attaching the trailing gas nozzle to a welding torch, this allows for easy connection of the trailing gas nozzle to the welding torch. This pivoting capability allows the trailing gas nozzle to be easily swung away when not in use, or allows for quick adjustment of the position of the trailing gas nozzle relative to the welding area or workpiece. For rapid fixation of the trailing gas nozzle relative to the welding torch, appropriate fixing elements can be provided, which, in particular, allow for tool-free manual fixing and release.

[0031] Preferably, the housing, the at least one inlet for each fluid, the channels with the openings, and possibly the at least one cooling fluid line are all made in one piece and are preferably manufactured using a 3D printing process. This allows the carrier gas nozzle to be manufactured quickly and cost-effectively.

[0032] The housing, the at least one inlet for each fluid, the gas channels with the openings, and possibly the at least one cooling fluid line are made of an aluminum alloy, for example. Copper or a copper alloy is also suitable for manufacturing the carrier gas nozzle.

[0033] The channels of the carrier gas nozzle preferably have a round or regular polygonal cross-section, preferably a square or hexagonal cross-section. This design ensures a uniform wall thickness between the gas channels, which leads to uniform heat dissipation and offers advantages in terms of manufacturing.

[0034] The housing can have a substantially rectangular base, and the sectors can also have a rectangular base. Any device for attaching the welding torch is preferably located on one of the wide sides of the rectangular housing. This variant offers advantages, particularly for essentially straight welding paths.

[0035] Alternatively, the housing can also have a substantially round base, and the sectors can have a substantially circular sector-shaped base. In this case, any device for attaching the welding torch is advantageously located essentially in the center of the housing. This design variant is particularly advantageous for arc-direct energy deposition (ARC), as it protects a larger welding area from air ingress.

[0036] The openings of all channels of the trailing gas nozzle can be arranged in one plane, which is particularly suitable for use with essentially flat welding areas and workpieces.

[0037] If the openings of all channels of the trailing gas nozzle are arranged on a curved surface, optimal protection of the welding area can be achieved even with non-flat workpieces, such as pipes, shaped pipes, boilers, etc. The curvature of the trailing gas nozzle is adapted to the curvature of the welding area or workpiece.

[0038] The present invention is explained in more detail with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an embodiment of a substantially rectangular entraining gas nozzle; Fig. 2 is a perspective view of the entraining gas nozzle according to Fig. 1 from below; Fig. 3 a section through a module of a carrier gas nozzle; Fig. 4 a schematic perspective view of a rectangular carrier gas nozzle with three rectangular sectors; Fig. 5 a sectional view through the carrier gas nozzle according to Fig. 4 along the section plane VI; Fig. 6 the flow profile of the fluid of the carrier gas nozzle according to Fig. 5 ; Fig. 7 a plan view of a rectangular entraining gas nozzle with six symmetrically arranged rectangular sectors; Fig. 8 a plan view of a rectangular entraining gas nozzle with three asymmetrically arranged rectangular sectors; Fig. 9 a plan view of a rectangular entraining gas nozzle with two symmetrically arranged rectangular sectors; Fig. 10 a schematic view of a entraining gas nozzle with six sectors according to Fig. 7 , wherein the flow parameters of the fluid of each sector are controlled depending on the geometry of the curved welding path; Fig. 11 a schematic view of a carrier gas nozzle with six sectors according to Fig. 7 , wherein the flow parameters of the fluid of each sector are controlled depending on the geometry of the straight welding path; Fig. 12 a schematic view of a carrier gas nozzle with two sectors according to Fig. 9 , wherein the flow parameters of the fluid of the sectors are controlled depending on the geometry of the welding path; Fig. 13 a plan view of a round carrier gas nozzle with a plurality of sectors which are constructed in a modular manner and connected to one another; Fig. 14 an exemplary temperature-time cooling curve for a workpiece during a welding process and a suitable control of the fluid parameters or properties of the fluid of the carrier gas nozzle; and Figs. 15A to 15C further exemplary temperature-time cooling curves for a workpiece during a welding process with three different cooling courses.

[0039] Fig. 1 shows a perspective view of a preferred embodiment of a substantially rectangular entraining gas nozzle 1 for flowing at least one fluid F i , in particular a shielding gas or a cooling liquid or mixtures of a gas and a liquid, over a welding area Y of a workpiece W along a welding path X. The entraining gas nozzle 1 has a housing 2 and, if appropriate, a device for fastening to a welding torch B. In order to carry out a rapid adjustment of the entraining gas nozzle 1 with respect to the welding torch B, the device can also be designed to be pivotable in order to be able to move the entraining gas nozzle 1 from the position of use (not shown). In this way, the process stability can be assessed, for example, in a welding start phase for quality control purposes.During the welding process, the trailing welding area Y is covered by the trailing gas nozzle 1, whereby the welding area Y is protected from air ingress and cooled in order to achieve optimum quality of the weld seam or the welding surface. The length of the trailing gas nozzle 1 is selected such that, at the desired welding speed v, the welding area Y is supplied with at least one fluid F i until the critical temperature T k of the workpiece W in the welding area Y, at which a reaction with atmospheric oxygen takes place, is undershot. The trailing gas nozzle 1 shown has a jacket 3 around the gas nozzle 4 of the welding torch B, via which the primary shielding gas is supplied to protect the arc during the welding process (see also . Fig. 2 ). A module M 1 is arranged on the casing 3 to form a first sector S 1 , which in turn is connected to three further modules M 2 , M 3 , M 4 to form the sectors S 2 , S 3 and S 4 . The connection between the modules M j can be designed, for example, by a detachable connection, i.e. by a screw connection, a latching connection, or by a non-detachable connection such as welding, soldering, gluing or the like. The carrier gas nozzle 1 can be expanded in a modular manner in order to achieve a shape of the carrier gas nozzle 1 calculated, for example, by simulation or parameter calculation (see also Fig. 10 bis 12 ). Instead of the interconnected modules M 1 to M 4, the housing 2 of the carrier gas nozzle 1 can also be manufactured in one piece and the sectors S 1 to S 4 can also be integrated in this common housing 2. The carrier gas nozzle 1 has at least one inlet E i for the at least one fluid F i, here one inlet E 1 to E 4 in each module M 1 to M 4 for one fluid F 1 to F 4 . The at least one fluid F i with corresponding flow parameters P i and properties Q i is flowed onto the welding area Y via a plurality of preferably parallel arranged channels 6 with openings 7 (see Fig. 3 ). Instead of a substantially rectangular shape of the carrier gas nozzle 1 in plan view, round or other shapes are also possible. The carrier gas nozzle 1 can also contain cooling fluid lines 9 in the modules M 1 to M 4, via which a cooling fluid K can be applied to the welding area Y in addition to the at least one fluid F i .

[0040] As already mentioned, the entraining gas nozzle 1 can be designed as a single piece and preferably manufactured using a 3D printing process. For example, a laser sintering process is suitable for this purpose, in which the material, in particular an aluminum alloy, is in powder form and melted by a laser. In this way, the entraining gas nozzle 1 according to the invention can be manufactured particularly cost-effectively, and the geometry of the individual elements can thus be easily adapted. All elements of the entraining gas nozzle 1, such as the housing 2, the at least one inlet E i for the at least one fluid F i , the channels 6, and possibly a cooling fluid channel 9, are manufactured in a single process.

[0041] Fig. 2 shows a perspective view of the carrier gas nozzle 1 according to Fig. 1 from below. The channels 6 with the openings 7 in the sectors S 1 to S 4 are visible, which here have a square cross-section. The ratio of the height of the channel 6 to the hydraulic diameter is preferably selected such that the flow within the channels 6 is calmed accordingly, resulting in a uniform, laminar flow of the fluid F i at the openings 7 of the channels 6. The size of the carrier gas nozzle 1 and also the number ni of the channels 6 in each sector S 1 are selected according to the respective application.

[0042] In the illustrated embodiment of the carrier gas nozzle 1 according to the Figuren 1 and 2the openings 7 of all channels 6 are arranged in one plane, which is particularly suitable for use on a substantially flat workpiece W. Alternatively, the openings 7 of the channels 6 can also be arranged on a curved surface. This allows the shape of the carrier gas nozzle 1 to be adapted to the shape of the workpiece W. For example, when welding a pipe, the carrier gas nozzle 1 can be concavely or convexly curved in order to be able to adapt to the outer or inner surface of the pipe (not shown). This optimally protects the welding area Y by the fluid F i and achieves optimal welding quality even with oxidation-sensitive materials, such as titanium in particular.

[0043] Fig. 3 shows a section through a module M j of a carrier gas nozzle 1. This shows the connection of the inlet E i for the fluid F i to a distribution chamber 15. In order to be able to optimally distribute the fluid F i flowing in from the inlet E i in the gas distribution chamber 10, an element 11 for distributing the fluid F i can additionally be arranged in the gas distribution chamber 10. Holes 12 lead from the distribution chamber 15 into the parallel channels 6. The distribution of the fluid F i can also take place in several stages in that the fluid F i reaches a first distribution chamber 10 via the inlet E i and is passed on via corresponding holes 12 into a second distribution chamber or several second gas distribution chambers before the fluid F i is distributed via corresponding holes to all channels 6 (not shown).Such cascading results in an optimal and uniform distribution of the fluid F i to all channels 6 and thus a uniform flow through the openings 7 to the welding area Y of the workpiece W to be protected and cooled.

[0044] Fig. 4 shows a schematic perspective view of a rectangular entraining gas nozzle 1 and the workpiece W underneath, the welding area Y of which is flowed with at least one fluid F i. In the entraining gas nozzle 1 shown, the openings 7 of the channels 6 for the fluid F i are divided into three rectangular sectors S 1 , S 2 and S 3. The number ni of channels 6 per sector S 1 can be the same or different. According to the invention, at least one flow parameter P i of the at least one fluid F i of each sector S 1 , S 2 and S 3 can be individually controlled. The welding process proceeds in the direction of the longitudinal extent of the workpiece W, which is indicated by the arrow of the welding speed v.

[0045] In Fig. 5 is a sectional view through the carrier gas nozzle 1 according to Fig. 4 with the three sectors S 1 , S 2 and S 3 along the section plane VI-VI and below in Fig. 6 the flow profile of the fluid F i of the carrier gas nozzle 1 according to Fig. 5 The flow profile shows a flow parameter P i of the fluid F i , here the flow velocity V Fi of the fluid F i in the transverse direction along the y-axis. According to the inventive design of the carrier gas nozzle 1, the flow parameter P i , here the flow velocity v Fi of the fluid F 1 , F 2 , F 3 used, of each sector S 1 , S 2 and S 3 is individually controlled. The sectors S 1 , S 2 and S 3 can of course be individually designed in different ways. For example, the sector S 1 can be provided with a diffuser as in Fig. 3 be designed because a particularly laminar flow is desired here in order to prevent oxidation on the workpiece W. The sectors S 2 and S 3, for example, only serve for cooling and therefore do not require a diffuser because the temperature there has cooled down so much that oxidation no longer takes place. This means that the sectors S 2 , S 3 can be manufactured geometrically in a simpler and therefore more cost-effective manner. Here, the flow velocity v F1 of the fluid F 1 in the first sector S 1 is selected to be higher than the flow velocities v F2 , v F3 of the fluids F 2 , F 3 of the sectors S 2 and S 3 , which are further away from the welding area Y to be protected and cooled along the welding path X than the sector S 1 . The control of the flow parameters P i of the fluids F i can be achieved by separate inlets E 1 , E 2 , E 3 for the fluids F 1 , F 2 and F 3 of each sector S 1 , S 2 and S 3.In this case, the type of fluid F i in each sector S 1 could also be individually changed, for example using a different fluid F 1 for sector S 1 than for sectors S 2 and S 3, or using a different composition of fluids F 2 and F 3. Likewise, the carrier gas nozzle 1 can be designed so that it has only one inlet E for a fluid F, and the inlet is divided between sectors S 1 , S 2 and S 3. If each sector S 1 , S 2 and S 3 has its own valve or flow regulator (not shown) for the fluid F, the flow parameter P i of the fluid F can be individually controlled in each sector S 1 , S 2 and S 3.The method according to the invention for flowing a fluid F i over a welding area Y of a workpiece W and the design of the carrier gas nozzle 1 according to the invention enables individual control of the fluids F i used, whereby the consumption of the fluids F i used and thus the costs can be minimized with optimal quality of the resulting welding result.

[0046] Fig. 7 shows a plan view of a rectangular carrier gas nozzle 1 with six symmetrically arranged rectangular sectors S 1 to S 6 . The inlet E for the fluid F or several inlets E 1 for the fluids F i are not shown. The welding torch B is arranged in the middle of the symmetrically constructed carrier gas nozzle 1. Assuming regularly arranged channels 6 in the carrier gas nozzle 1 shown here, the number n 3 and n 4 of the channels 6 of the sectors S 3 and S 4 is less than the number n 1 , n 2 , n 5 and n 6 of the channels 6 of the sectors S 1 , S 2 , S 5 and S 6 . The respective design of the carrier gas nozzle 1 and division of the sectors S 1 is optimally adapted to the workpiece W to be produced. There are hardly any limits to the design options.

[0047] In Fig. 8 is a plan view of a rectangular entraining gas nozzle 1 with three asymmetrically arranged rectangular sectors S 1 , S 2 and S 3 . Such a configuration will be useful if the entraining gas nozzle 1 or the welding torch B is generally moved over the workpiece W in a preferred welding direction (see arrow of the welding speed v), since the welding area Y covered by the entraining gas nozzle 1 after welding must always be supplied with fluid F i and must be protected and cooled.

[0048] Fig. 9 shows a plan view of a rectangular carrier gas nozzle 1 with two symmetrically arranged rectangular sectors S 1 and S 2, each with a corresponding number n 1 or n 2 of channels 6. This design variant of the carrier gas nozzle 1 will be particularly useful for straight welding paths X, which are swept in both directions.

[0049] Fig. 10 shows a schematic view of a carrier gas nozzle 1 with six sectors S 1 to S 6 according to Fig. 7 the control of the flow parameters P i of the fluid F i of the sectors S i depending on the geometry of a curved welding path X. When the carrier gas nozzle 1 moves during the welding process along the welding path X in the direction of the arrow of the welding speed v, it is expedient to only control the sectors S 2 and S 4, i.e. only the flow of the fluids F 2 and F 4 in the sectors S 2 and S 4 is activated, since the freshly welded area is only covered by these two sectors S 2 and S 4 due to the curved shape of the welding path X. This means that a large amount of fluid F i , which would otherwise also flow via the other sectors S 1 , S 3 , S 5 and S 6 onto the welding area Y, can be saved.

[0050] Fig. 11 shows a schematic view of a carrier gas nozzle 1 with six sectors S 1 to S 6 according to Fig. 7 . When the trailing gas nozzle 1 moves during the welding process along the essentially straight welding path X in the direction of the arrow of the welding speed v, it is expedient to only control the sector S 4, i.e. only activate the flow of the fluid F 4 in sector S 4, since the freshly welded area is only covered by this sector S 4 due to the straight welding path X.

[0051] In Fig. 12 is a schematic view of a carrier gas nozzle 1 with two sectors S 1 , S 2 according to Fig. 9 when welding along a straight welding path X. When the trailing gas nozzle 1 moves during the welding process in the direction of the arrow of the welding speed v, it is expedient to only control the sector S 1, i.e. only activate the flow of the fluid F 1 in sector S 1, since the freshly welded area is only covered by this sector S 1 due to the straight welding path X and the welding direction.

[0052] Fig. 13 shows a plan view of a round carrier gas nozzle 1 with a plurality of sectors S i , which are constructed in a modular manner and connected to one another. The individual modules M j can have various shapes, as in this case, they have a substantially triangular outline. This allows for an individual combination of the carrier gas nozzle 1 from different modules M j to form the desired sectors S i .

[0053] In Fig. 14 shows an example temperature-time cooling curve in which the temperature T (in °C) at a stationary point on the workpiece W during the welding process, during which the welding torch B with the trailing gas nozzle 1 is moved over the workpiece W at the welding speed v, is shown as a function of time t (in s). At the start of the welding process during phase I, the temperature T is below the critical temperature T k relevant for oxidation. In this phase I, the welding area is cooled, for example, only with compressed air. During phase I, compressed air is therefore used as fluid F i in the corresponding sector S i of the trailing gas nozzle 1, which is located directly above the point at which the temperature T is measured.During phase II, the temperature T rises above the critical temperature T k, which is why carbon dioxide CO 2, for example, is used as the fluid for the sector S i , which is located above the point where the temperature T is measured. If the temperature T rises above the so-called dissociation temperature T diss , an inert gas, e.g. argon, is added during phase III to protect the melt from oxidation during the welding process. After the temperature falls below the dissociation temperature T diss during phase IV, the cheaper carbon dioxide CO 2, for example, can be used instead of argon. If a certain limit temperature TG is undershot, an additional liquid, e.g. water, is used to cool the workpiece more quickly (phase V). If the measured temperature T finally falls below the critical temperature T k , the workpiece W can again be supplied with compressed air exclusively (phase VI). Fig. 14 shows only the control of the type of fluid F i of the sectors S i of the carrier gas nozzle 1 as a function of the temperature T measured at one point. When several temperature sensors are arranged, the properties Q i or flow parameters P i of the fluids F i for the sectors S i that are located directly above the point of the respective temperature sensor can be adapted to the respective measured temperature T or the temperature profiles can be set and changed by changing the properties Q i or flow parameters P i of the fluids F i for the sectors S i. In this way, the temperature-time cooling profile can also be adapted to the geometry of the workpiece W. For example, the workpiece W can have less material at the edge so that the heat input during the welding process is lower and thus the cooling after the welding process also needs to be less, whereas in the middle of the workpiece W a higher cooling capacity will be required.

[0054] Finally, the Fig. 15A bis 15C Further exemplary temperature-time cooling curves for a workpiece W during a welding process with three different cooling courses starting from phase IV after falling below the dissociation temperature T diss .

[0055] According to Figur 15A After the temperature T has cooled below the dissociation temperature T diss in phase IV, very rapid cooling is achieved, for example by a maximum volume flow of the fluid F i used in the respective sector S i of the carrier gas nozzle 1, for example carbon dioxide CO 2. The cooling rate is, for example, between 50°C / s and 1000°C / s, preferably between 100°C / s and 500°C / s, depending on the geometry of the workpiece W and the material accumulation during the manufacturing process. During phase V, after a limit temperature TG has been undershot, very rapid cooling initially takes place through the use of an additional, external cooling medium in the respective sector S i. Over the course of time t, the cooling capacity of the external cooling medium is reduced, which is why the decline in curve 1 becomes flatter during phase V.In phase VI, after the temperature T drops below the critical temperature T k, the cooling is influenced, for example, by controlling the volume flow of an additional cooling gas, such as air.

[0056] At Fig. 15B the cooling in phase IV is due to a lower volume flow of a protective gas in the respective sector S i compared to the temperature curve according to Fig. 15A Thus, the duration of Phase IV is Fig. 15A higher. In Phase V, for example, the constant addition of an external cooling medium in the respective sector S i results in an essentially constant drop in temperature T. In Phase VI, for example, the cooling is again influenced by controlling the air flow rate.

[0057] Fig. 15C shows a temperature-time profile in which the cooling in phase IV is slowed down by reducing the volume flow of the protective gas in the respective sector S i. As a result, phase IV is considerably longer than in the profiles according to Fig. 15A und 15B After falling below the dissociation temperature T diss in phase V, according to Fig. 15C The cooling takes place with increasing drop by increasing the cooling capacity by an external cooling medium in the respective sector S i. After falling below the critical temperature T k in phase VI, the cooling is then influenced again by controlling the volume flow of an additional cooling gas, for example air. Fig. 15A bis 15C show different possibilities of influencing the temperature-time cooling profile of the workpiece W by different flow parameters P i or properties Q i of the fluids F i used in the respective sector S i of the carrier gas nozzle 1.

[0058] The present invention allows the amount of fluids F i used to be minimized and the welding quality to be optimized.

Claims

1. A method for allowing at least one fluid (Fi) to flow over a welding area (Y) of a workpiece (W) along a welding path (X) during a welding process, wherein the at least one fluid (Fi) is flowed onto the welding area (X) via at least one inlet (Ei) and a plurality of channels (6) having openings (7), characterised in that the openings (7) of the channels (6) are divided into at least two sectors (Si), and at least one flow parameter (Pi) of the at least one fluid (Fi) of each sector (Si), is individually controlled, wherein at least one flow parameter (Pi) of at least one fluid (Fi) of at least one sector (Si) is controlled depending on the geometry of the welding path (X) and / or depending on the geometry of the workpiece (W).

2. The method according to claim 1, characterised in that at least one property (Qi) of the at least one fluid (Fi) is individually controlled.

3. The method according to claim 1 or 2, characterised in that at least one flow parameter (Pi) and / or at least one property (Qi) of the at least one fluid (Fi) of each sector (Si) is individually controlled depending on at least one temperature (Tk) of the welding area (Y) of the workpiece (W).

4. The method according to claim 3, characterised in that the at least one temperature (Tk) of the welding area (Y) of the workpiece (W) is measured with at least one temperature sensor (8), is estimated by simulation or parameter calculation, and / or is determined via the energy introduced into the workpiece (W) during the welding process.

5. The method according to claim 3 or 4, characterised in that when the temperature falls below or exceeds a predetermined limit temperature (TG), at least one flow parameter (Pi) and / or at least one property (Qi) of the at least one fluid (Fi) of at least one sector (Si) is changed.

6. The method according to claim 3 or 4, characterised in that at least one flow parameter (Pi) and / or at least one property (Qi) of the at least one fluid (Fi) of each sector (Si) is individually controlled depending on a predetermined temperature-time cooling profile of the workpiece (W).

7. The method according to claim 2 to 6, characterised in that at least one property (Qi) of at least one fluid (Fi) of at least one sector (Si) is controlled depending on the geometry of the welding path (X) and / or depending on the geometry of the workpiece (W).

8. The method according to one of claims 1 to 7, characterised in that at least one flow parameter (Pi) and / or at least one property (Qi) of at least one fluid (Fi) of at least one sector (Si) is controlled depending on the welding process.

9. A carrier gas nozzle (1) for allowing at least one fluid (Fi) to flow over a welding area (Y) of a workpiece (W) along a welding path (X) during a welding process, with a housing (2), at least one inlet (Ei) for the at least one fluid (Fi) and a plurality of channels (6) having openings (7) through which the at least one fluid (Fi) flows onto the welding area (Y), wherein the channels (6) with the openings (7) are divided into at least two sectors (Si), with at least one inlet (Ei) for at least one fluid (Fi), which sectors (Si) are designed for the individual control of at least one flow parameter (Pi) of the at least one fluid (Fi) of each sector (Si), wherein the at least two sectors (Si) are arranged depending on the geometry of the welding path (X) and / or the geometry of the workpiece (W), characterised in that in each sector (Si) its own valves or its own flow controllers for the at least one fluid (Fi) are provided, and that a control is provided with which the control of the at least one flow parameter (Pi) of the at least one fluid (Fi) of each sector (Si) can be carried out by the sector-by-sector control by means of the valves or the flow controllers, so that at least one flow parameter (Pi) of at least one fluid (Fi) of at least one sector (Si) can be controlled depending on the geometry of the welding path (X) and / or depending on the geometry of the workpiece (W).

10. The carrier gas nozzle (1) according to claim 9, characterised in that the sectors (Si) are constructed in the form of interconnectable modules (Mj).

11. The carrier gas nozzle (1) according to claim 9 or 10, characterised in that at least one temperature sensor (8) is provided for measuring at least one temperature (Tk) of the welding area (Y) of the workpiece (W).

12. The carrier gas nozzle (1) according to one of claims 9 to 11, characterised in that at least one cooling fluid line (9) is provided with at least one mouth for applying a cooling fluid (K) to the welding area (Y) of the workpiece (W).

13. The carrier gas nozzle (1) according to claim 12, characterised in that a nozzle, in particular an atomiser nozzle, is arranged at the at least one mouth.

14. The carrier gas nozzle (1) according to one of claims 9 to 13, characterised in that the housing (2), the at least one inlet (Ei) for each fluid (Fi), the channels (6) with the openings (7), and at most the at least one cooling fluid line (9) are produced in one piece and preferably in a 3D printing process.

15. The carrier gas nozzle (1) according to one of claims 9 to 14, characterised in that the channels (6) have a round or regularly polygonal cross-section.