Welding apparatus having a nozzle device for cooling the workpiece during the welding process
By equipping the welding device with a rotatable cooling nozzle array and an automatically adjusted cooling strategy, the problem of workpiece thermal management in arc additive manufacturing is solved, achieving efficient cooling of workpieces with complex geometries and improving production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LINDE AG
- Filing Date
- 2021-10-06
- Publication Date
- 2026-05-26
AI Technical Summary
In the process of arc additive manufacturing, the workpiece heats up during the welding time, causing changes in electrical and thermal conditions. The layer structure and mechanical properties become uncontrollable, and existing cooling methods are limited to simple structures or rotary welding, which cannot adapt to welding complex geometries.
Design a welding device equipped with a cooling nozzle array. The nozzle array can rotate around the welding torch and adjust the flow rate of the cooling medium. The cooling strategy is automatically adjusted according to the temperature signal and the movement of the welding torch to achieve efficient cooling of the workpiece.
It achieves efficient cooling of workpieces with complex geometries, maintains mechanical and material properties, increases production speed, reduces thermal warpage and tempering color, predicts layer structure, and improves the accuracy of 3D structures.
Smart Images
Figure CN116234657B_ABST
Abstract
Description
[0001] This invention relates to a welding apparatus, particularly for arc welding processes, such as in the form of WAAM (Wire Arc Additive Manufacturing).
[0002] When using arc technology for joining, welding, and generative joining (also known as wire arc additive manufacturing), heat is introduced into the component or structure by melting or fusing the base material and filler material. In particular, heat input accumulates when multiple layers of filler material are introduced.
[0003] In WAAM (Wire Arc Additive Manufacturing), a pre-established MSG method is used to coat metal material layer by layer, thereby creating a 3D structure or corresponding workpiece. The problem is that the workpiece heats up throughout the welding time, causing changes in electrical conditions, thermal conditions, layer structure, deformation, and tempering color.
[0004] Furthermore, the material properties of mechanical technology undergo uncontrolled changes because each additional layer has a thermal effect on the previous layers.
[0005] Currently, attempts are being made to address these issues by pausing the cooling process. The high melting point of the MSG method is limited by the forced implementation of this cooling pause.
[0006] In principle, it is possible to use airflow to cool the WAAM structure, thereby improving metallurgical properties and requiring little or no cooling pauses. However, such a solution is only suitable for very simple structures, such as tubular (circular path) structures, and only applicable when the structure to be constructed rotates around its own axis and the welding torch is not moved. In this case, the cooling nozzle can always be kept at a certain distance from the welding torch. The cooling position does not need to be changed.
[0007] Once the tube stops rotating around its own axis (turntable), the welding torch moves, or welds more complex geometries, the location to be cooled will constantly change.
[0008] From this point of view, the object of the present invention is to provide a welding apparatus that improves upon the aforementioned problems.
[0009] This objective is achieved by a welding apparatus having the features described in this invention. Advantageous embodiments of the invention are given in the corresponding technical solutions and are described below.
[0010] According to the present invention, a welding apparatus for welding at least one workpiece is disclosed, the welding apparatus comprising:
[0011] - A welding torch, designed to generate an electric arc for welding the at least one workpiece; and
[0012] - A nozzle device arranged at a welding torch, the nozzle device having a cooling nozzle array having at least one row of cooling nozzles, wherein the respective cooling nozzles are capable of being loaded with a predefined volumetric flow rate of cooling medium to cool the workpiece (particularly during the welding process), and are designed to spray the cooling medium onto the surface of the workpiece to be cooled.
[0013] Therefore, the present invention advantageously allows for cooling of the workpiece near the energy introduction to eliminate overheating, even if the direction and / or orientation of the welding torch changes during welding, because there are multiple cooling nozzles on which cooling medium can be applied.
[0014] According to one embodiment of the invention, the at least one row of cooling nozzles extends linearly or flexibly, particularly in annularly.
[0015] In particular, the cooling nozzles of the nozzle assembly can be arranged side by side, preferably equidistant, in the circumferential direction of the welding torch, so that the array of cooling nozzles extends circumferentially around the welding torch.
[0016] This is particularly advantageous in applications requiring good passability. Due to the annular arrangement, the cooling nozzles can be positioned around the welding torch within minimal installation space.
[0017] Furthermore, according to one embodiment of the invention, the cooling nozzle array is configured to have multiple rows of cooling nozzles, wherein, in particular, the cooling nozzle array has at least one row of cooling nozzles, which is a radial row oriented towards the center, preferably multiple rows of cooling nozzles, these rows being radial rows oriented towards the center, and at least two nozzles are arranged on this row, wherein these nozzles are arranged at different radial distances from the center, wherein, in particular, the cooling nozzle array is represented as a two-dimensional field or two-dimensional array composed of cooling nozzles, wherein, in particular, each row may extend linearly or flexibly, particularly extending circumferentially. Especially for cases where multiple rows of cooling nozzles are used or present, each cooling nozzle may also be directed inwards or towards the still-hot weld or structure.
[0018] Furthermore, according to one embodiment of the invention, the plurality of cooling nozzles of the cooling nozzle array (particularly a selected row, selected multiple rows, or all rows) are configured to be loaded with an adjustable volumetric flow rate of a specific cooling medium.
[0019] According to another embodiment of the invention, at least one cooling nozzle of the nozzle device is capable of being loaded with a first cooling medium, and at least one other cooling nozzle of the nozzle device is capable of being loaded with a second cooling medium, wherein the composition of the second cooling medium is different from that of the first cooling medium.
[0020] Therefore, the cooling medium for each cooling nozzle can be varied, or different cooling nozzles can be loaded with different cooling media. Thus, for example, it is feasible to load the cooling nozzles closer to the arc with a cooling medium, particularly a gas, especially an inert gas, while the cooling nozzles farther from the arc can be loaded with an active gas or a gas with increased active components, or also with a liquid, such as water. This improves the cooling effect without affecting the arc, for example, due to the presence of water.
[0021] According to a particularly preferred embodiment of the invention, the cooling nozzle array is configured to rotate about a rotation axis, thereby enabling the cooling nozzles, in particular, to move about the welding torch. This allows the coolant flow emitted by one or more cooling nozzles to be preferably directed toward the still-hot surface of the at least one workpiece, even if the welding torch has changed its direction of guidance and / or movement during welding. In this case, the rotation axis may coincide with the longitudinal axis of the welding torch, but may also have an inclination relative to that longitudinal axis (e.g., when the cooling nozzle array is able to tilt about another tilting axis, see below).
[0022] Furthermore, according to one embodiment of the invention, the welding apparatus is configured to have at least one electric motor or pneumatic drive (or similar motion unit) to rotate the cooling nozzle array about a rotation axis.
[0023] According to another embodiment of the invention, the welding apparatus is configured to adjust the rotation angle of the cooling nozzle array relative to the rotation axis by referring to a temperature signal and / or by referring to an automatic calculation based on a known or planned sequence of motion of the welding torch during welding.
[0024] Furthermore, according to one embodiment of the invention, the cooling nozzle array is configured to tilt about an inclined axis, particularly about a horizontal inclined axis. This makes it easier to always direct the cooling medium flow towards the optimal cooling position (typically after the welding process or after the instantaneous weld pool in the direction of the welding torch's movement, thus allowing the cooling or cooling position to follow the welding torch).
[0025] Furthermore, according to one embodiment of the invention, the welding apparatus is configured to have temperature sensors (particularly advantageously optical sensors) configured to detect the temperature distribution of the workpiece produced by means of the welding apparatus.
[0026] According to another embodiment of the invention, the welding apparatus is configured to control or adjust the volumetric flow rate of the cooling medium discharged from the corresponding cooling nozzles by referring to a detected temperature distribution or temperature information, thereby making the temperature distribution particularly close to the desired temperature distribution. Furthermore, in this way, the effective cooling point on the surface of the at least one workpiece can be controlled by referring to the temperature information.
[0027] The nozzle assembly may have valves, for example, located upstream of the cooling nozzle, to control the volumetric flow rate. These valves may be electrically or mechanically driven or actuated. These valves may be, for example, proportional valves. Alternatively, a movable panel may be used instead of the valves.
[0028] Furthermore, the points on the workpiece where heat accumulation occurs can be calculated by referring to known path profiles (e.g., through simulation). Correspondingly, more targeted cooling can be applied at these points than at points where heat accumulation was not calculated.
[0029] Preferably, the cooling strategy is calculated with reference to the warpage. The flow rate or volumetric flow rate of the cooling medium through the corresponding cooling nozzle is preferably adjustable, for example, by using a proportional valve.
[0030] To enhance cooling, welding equipment or nozzle devices are designed to open multiple cooling nozzles simultaneously or discharge cooling medium through multiple cooling nozzles simultaneously.
[0031] Each cooling nozzle can be threaded onto the nozzle assembly, for example, making it easy to replace these cooling nozzles.
[0032] Furthermore, each cooling nozzle can have different flow characteristics, and thus can be adapted to the corresponding application. In particular, the corresponding cooling nozzle can, for example, generate a rotationally symmetric flow field but may also generate a non-rotationally symmetric flow field. For this purpose, the corresponding cooling nozzle can be designed, for example, as a slit nozzle.
[0033] Furthermore, according to one embodiment of the invention, the welding apparatus is configured to allow a cooling nozzle to carry a lower volumetric flow rate of cooling medium than another cooling nozzle, thereby reducing the risk of interaction between the cooling medium and the process gas (e.g., shielding gas) of the welding process, wherein the cooling nozzle is located closer to the arc than the other cooling nozzle. The process gas may be, for example, a shielding gas and / or a focused gas emitted from the welding torch, to protect the weld joint from oxidation or to control the arc.
[0034] Furthermore, according to one embodiment of the invention, the welding apparatus is configured to discharge one or more of the following media as cooling media via at least one cooling nozzle: argon, helium, nitrogen, hydrogen, air, carbon dioxide, or mixtures of the above gas types. The welding apparatus may have a container for each cooling medium used, which is fluidly connected to the nozzle device, or is capable of being fluidly connected to the nozzle device (e.g., via the aforementioned valve).
[0035] Another aspect of the invention relates to a method for welding at least one workpiece, wherein the workpiece is constructed layer by layer by means of a welding apparatus according to the invention and cooled by means of a nozzle device.
[0036] This invention can be used particularly effectively in additive manufacturing (e.g., WAAM) because a large amount of heat is input into the workpiece in this technology.
[0037] However, the solution according to the present invention can also be used in conventional welding processes or weld overlay.
[0038] The principles of this invention are particularly advantageous for applications where the welding direction changes frequently or continuously, or for applications where warping is exacerbated. This invention can be used in methods of providing filler material in the form of metal wire or powder.
[0039] This invention is applicable to virtually all welding processes (especially MSG, WIG, plasma welding, laser welding, and special methods such as hybrid welding and tandem welding).
[0040] This invention advantageously allows for the preservation of mechanical and technical material properties. Simultaneously, it enables increased production speed because no cooling stage is required between layers (typically increasing speed by over 50%).
[0041] Furthermore, this invention makes it possible to minimize thermal warpage. Layer structures become predictable, and it is possible to achieve slightly less inhomogeneity in the 3D structures to be produced (improving so-called near-net-shape). Additionally, this invention makes it possible to reduce tempering color.
[0042] The embodiments, further features, and advantages of the present invention will now be explained with reference to the accompanying drawings. The drawings show:
[0043] Figure 1 A top view schematic diagram of one embodiment of the welding apparatus according to the present invention during the welding process, wherein the direction of the welding torch is changed by 90°;
[0044] Figure 2 A top view schematic diagram of one embodiment of the welding apparatus according to the present invention during the welding process, wherein the direction of the welding torch is changed by 180°;
[0045] Figure 3 A schematic side view of one embodiment of the welding apparatus according to the present invention, having an array of cooling nozzles rotatably mounted at the welding torch;
[0046] Figure 4 Figure 3 Another schematic side view of the welding apparatus shown; and
[0047] Figure 5 A schematic diagram of another embodiment of the welding apparatus according to the present invention.
[0048] Figure 1 and Figure 2 A schematic top view of one embodiment of the welding apparatus 1 according to the invention during the welding process is shown, wherein the direction of the welding torch 2 is changed by 90° (see reference). Figure 1 ) or 180℃ (refer to) Figure 2 ).
[0049] according to Figure 1 and Figure 2 The welding apparatus 1 has a welding torch 2 to perform the welding process. The welding torch is designed to generate an electric arc, such that the surface of, for example, welding filler or the workpiece to be produced, is molten, so as to build the workpiece layer by layer, for example, in the WAAM method.
[0050] In order to selectively cool the workpiece during the welding process in this case, the welding apparatus 1 has a nozzle device 20 arranged at the welding torch 2, the nozzle device having a cooling nozzle array 21 having at least one row 22 of cooling nozzles 23, wherein the respective cooling nozzles 23 can be loaded with an adjustable volumetric flow rate of cooling medium 4 to cool the workpiece.
[0051] Preferably, according to Figure 1 and Figure 2 The cooling nozzle array 21 is rotatable about the rotation axis R, thereby enabling the cooling nozzle 23 to move specifically around the welding torch 2. Figure 1 and Figure 2 In the middle, the axis of rotation is perpendicular to the plane of the plate.
[0052] Therefore, for example, when the direction of welding torch 2 changes by 90°, such as Figure 1 As shown, the cooling position 230, i.e. the surface area 230 of the workpiece to which the cooling medium 4 is applied, can be adapted to a change in direction by rotating the cooling nozzle array around the rotation axis R. Ideally, the cooling position is located after the instantaneous weld pool in the direction of movement B of the welding torch 2, which is generated by the arc of the welding torch. Figure 2 The adjustment of the cooling position 230 is shown when the direction of the welding torch 2 changes by 180°.
[0053] Figure 1 and Figure 2 The welding apparatus 1 shown can, for example, be based on Figure 3 The design incorporates a cooling nozzle array 21 with at least one row 22 of cooling nozzles 23, each at a different distance from the welding torch arc 3. The cooling nozzle array 21 is pivotable about a rotation axis R, with the rotation angle W adjustable by means of a suitable actuator that rotates the cooling nozzle array 21. Additionally, the cooling nozzle array can be tilted or pivoted about an inclined axis y, for example, a horizontal inclined axis y in this case. A specific cooling medium 4 can be discharged through each cooling nozzle 23 at its own varying volumetric flow rate. Different cooling media 4, 40 can also be discharged via the cooling nozzles 23. Furthermore, the rotation angle W of the cooling nozzle array 21 relative to the rotation axis R and / or the tilt angle W' relative to the inclined axis y can be adjusted with reference to a temperature signal, which can be provided, for example, by a temperature sensor 24. The temperature signal can also be used to adjust the volumetric flow rate of the cooling media 4, 40.
[0054] The cooling medium may be one of the following: argon, helium, nitrogen, hydrogen, air, carbon dioxide, or a mixture of the above gas types.
[0055] like Figure 4 As further shown in the middle, according to Figure 3 The cooling nozzle array 21 of the welding apparatus 1 may have multiple rows 22 of cooling nozzles 23, wherein, for example, there is the possibility of directing the coolant flow 4 inward toward the outermost row 22 of cooling nozzles so as to concentrate the cooling capacity on the path taken by the welding torch 2.
[0056] Figure 5 Another embodiment of the welding apparatus 1 according to the invention is shown, wherein... Figure 3 and Figure 4 Conversely, the cooling nozzles 23 are arranged here to surround the welding torch 2 in a circumferential direction U and preferably to be equidistant from each other, so that the cooling nozzle array 21 extends circumferentially around the welding torch 2.
Claims
1. A welding apparatus (1) for welding at least one workpiece, said welding apparatus comprising: - Welding torch (2), which is designed to generate an electric arc (3) to weld the at least one workpiece; - A nozzle device (20) arranged at the welding torch (2), the nozzle device having a cooling nozzle array (21), wherein the cooling nozzle array (21) has at least one row of cooling nozzles, the at least one row being a radial row, and at least two cooling nozzles arranged on the row, wherein the corresponding cooling nozzles (23) can be loaded with an adjustable volumetric flow rate of cooling medium (4) to cool the workpiece. The cooling nozzle array (21) is rotatable about a rotation axis (R), thereby allowing the cooling nozzles (23) to move around the welding torch (2). The cooling nozzle array (21) has multiple rows (22) of cooling nozzles (23). The cooling nozzles (23) of the nozzle device (20) are arranged side by side in the circumferential direction (U) of the welding torch (2), thereby allowing the cooling nozzle array (21) to extend circumferentially around the welding torch (2).
2. The welding apparatus according to claim 1, characterized in that, The cooling nozzles (23) of the nozzle device (20) are arranged equidistantly in the circumferential direction (U) of the welding torch (2).
3. The welding apparatus according to claim 1, characterized in that, The multiple cooling nozzles (23) of the cooling nozzle array (21) can be loaded with a specific cooling medium (4) at an adjustable volumetric flow rate.
4. The welding apparatus according to claim 1 or 2, characterized in that, At least one cooling nozzle (23) is capable of being loaded with a first cooling medium, and at least one other cooling nozzle is capable of being loaded with a second cooling medium, wherein the composition of the second cooling medium is different from that of the first cooling medium.
5. The welding apparatus according to claim 1 or 2, characterized in that, The welding device (1) is designed to adjust the rotation angle (W) of the cooling nozzle array (21) relative to the rotation axis (R) by referring to a temperature signal and / or an automatic calculation based on the known movement sequence of the welding torch (2) during welding.
6. The welding apparatus according to claim 1 or 2, characterized in that, The cooling nozzle array (21) is tiltable about the tilt axis (y).
7. The welding apparatus according to claim 1 or 2, characterized in that, The welding apparatus (1) has at least one temperature sensor (24) configured to detect the temperature distribution of the workpiece produced by means of the welding apparatus (1).
8. The welding apparatus according to claim 7, characterized in that, The welding apparatus (1) is designed to control the volumetric flow rate of the cooling medium discharged by the corresponding cooling nozzle (23) with reference to the detected temperature distribution.
9. The welding apparatus according to claim 1 or 2, characterized in that, The corresponding cooling nozzle (23) is fixed to the nozzle assembly (20) by a thread.
10. The welding apparatus according to claim 1 or 2, characterized in that, The welding apparatus (1) is designed to load a lower volumetric flow rate of the cooling medium (4) on the cooling nozzle (23) of the cooling nozzle array (21) than on the other cooling nozzle (23), in order to reduce the risk of the cooling medium (4) interacting with the process gas of the welding process, and the cooling nozzle is closer to the arc (3) than the other cooling nozzle (23).
11. The welding apparatus according to claim 1 or 2, characterized in that, The welding apparatus (1) is designed to discharge one of the following media as a cooling medium via at least one cooling nozzle (23): argon, helium, nitrogen, hydrogen, air, carbon dioxide, or a mixture of the above gas types.
12. The welding apparatus according to claim 6, characterized in that, The cooling nozzle array (21) is tiltable about a horizontal tilt axis.
13. A method for welding at least one workpiece, wherein the workpiece is constructed layer by layer by means of a welding apparatus (1) according to any one of the preceding claims and cooled by means of the nozzle apparatus (20).