Laser treatment of weld seams

Abstract

A method of manufacturing a component is provided. The method includes the step of welding at least two workpieces together to form a weld joint including at least one silicate island. The method continues with the step of laser cleaning the weld joint to remove at least a portion of the at least one silicate island from a top surface of the weld joint.

Description

[0001] Cross-reference to related applications

[0002] This PCT international patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 086,615, filed on October 2, 2020, entitled “Laser Processing Of Weld Seams”, the entire disclosure of which is incorporated herein by reference. Background Technology 1. Technical Field

[0004] This disclosure relates to welding between steel workpieces, and more specifically, to the treatment of weld seams.

[0005] 2. Related Technologies

[0006] Many metal automotive components (such as vehicle frames and chassis) are coated with an electrophoretic coating to improve corrosion resistance. To improve the adhesion between the electrophoretic coating and the base metal, in many cases, a phosphate layer is first applied to the component, allowing the electrophoretic coating to adhere to it. A known problem is that silicate islands, which typically form naturally on the outer surface of weld joints, can inhibit the adhesion of the phosphate layer to the base metal in the weld joint area. Therefore, without cleaning operations to remove the silicate islands, the weld joint may become susceptible to corrosion earlier than the surrounding area. Some known methods for removing silicate islands from weld joints to improve adhesion between these weld joints and the phosphate layer include chemical treatment, mechanical grinding, and shot peening. However, these operations can be costly, and in some cases, certain weld joints may be difficult for workers to access.

[0007] There remains a significant and ongoing need for improved methods to remove silicate islands from welded joints at a higher speed and lower cost. Summary of the Invention

[0008] One aspect of this disclosure relates to a method of manufacturing a component. The method includes the step of welding at least two workpieces together to form a weld joint comprising at least one silicate island. The method further includes the step of laser cleaning the weld joint to remove at least a portion of at least one silicate island from the top surface of the weld joint.

[0009] According to another aspect of this disclosure, the laser cleaning step does not remove the material surrounding at least one silicate island at the weld joint.

[0010] According to another aspect of this disclosure, the laser cleaning step includes directing a laser beam onto the entire top surface of both the material surrounding the at least one silicate island and the weld joint.

[0011] According to another aspect of this disclosure, the method proceeds to the step of applying a phosphate layer to the weld joint after the step of laser cleaning the weld joint.

[0012] According to another aspect of this disclosure, the method continues with the step of applying a coating onto the phosphate layer.

[0013] According to another aspect of this disclosure, the coating is an electrophoretic coating or a paint layer.

[0014] According to another aspect of this disclosure, the step of laser cleaning the welded joint includes directly guiding a pulsed laser beam from a laser head onto the top surface of the welded joint.

[0015] According to another aspect of this disclosure, the laser head is attached to the end of the robotic arm.

[0016] According to another aspect of this disclosure, the laser has a power of 1kW to 2kW.

[0017] According to another aspect of this disclosure, the laser beam moves along the top surface of the weld joint at a speed that can vary between 5 mm / s and 30 mm / s. In a currently preferred embodiment, the laser beam moves at a speed between 5 mm / s and 6 mm / s.

[0018] Another aspect of this disclosure relates to a method of manufacturing a component. The method includes the step of preparing a component comprising at least one welded joint having at least one silicate island. The method further includes the step of directly guiding a laser beam at the top surface of the at least one welded joint. The method then proceeds to the step of removing at least a portion of the at least one silicate island using the laser beam, without removing material surrounding the at least one silicate island from the at least one welded joint.

[0019] According to another aspect of this disclosure, the laser beam is emitted from a laser head located at the end of the robotic arm.

[0020] According to another aspect of this disclosure, the laser beam has a power of 1kW to 2kW.

[0021] According to another aspect of this disclosure, the laser beam moves along the top surface of the welded joint at a rate of 5 mm to 35 mm per second.

[0022] Another aspect of this disclosure relates to a manufacturing component comprising at least two metal parts joined together at a weld joint. The weld joint has been formed according to a welding process comprising the steps of welding at least two workpieces together to form a weld joint comprising at least one silicate island, and laser cleaning the weld joint to remove material from the top surface of the weld joint, thereby reducing the size of at least one silicate island.

[0023] According to another aspect of this disclosure, a phosphate layer is provided on the welded joint.

[0024] According to another aspect of this disclosure, a coating is provided on the phosphate layer.

[0025] According to another aspect of this disclosure, the forming process also includes directly guiding a pulsed laser beam from a laser head onto the top surface of the weld joint.

[0026] According to another aspect of this disclosure, at least two components are made of steel or alloy steel.

[0027] According to another aspect of this disclosure, during the laser cleaning step, the material surrounding at least one silicate island at the weld joint is not removed from the weld joint. Attached Figure Description

[0028] These and other features and advantages of this disclosure will be readily apparent, as they will become more readily understood by referring to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0029] Figure 1 It is a cross-sectional view of two workpieces joined together at a weld joint to form a component, wherein the weld joint is undergoing a laser cleaning operation;

[0030] Figure 2 The component is shown, and a phosphate coating is applied to the outer surface of the component;

[0031] Figure 3 The component is shown, and an additional layer is applied to the phosphate coating;

[0032] Figure 4 This is a cross-sectional view of the welded joint before the laser cleaning operation;

[0033] Figure 5 The laser cleaning mechanism is shown;

[0034] Figure 6 This is a cross-sectional view of the welded joint after laser cleaning.

[0035] Figure 7This is a schematic diagram showing the workspace where laser cleaning operations can be performed; and

[0036] Figure 8 This is a schematic diagram showing another workspace where laser cleaning operations can be performed. Detailed Implementation

[0037] Reference Figure 1 One aspect of this disclosure relates to a process in which two or more workpieces 20a, 20b are welded together to form a component 22 (e.g., an automotive component), and then the resulting weld joint 24 is cleaned using a laser cleaning operation before a phosphate coating 28 is applied to the component 22 to remove silicate islands 26 from the weld joint 24.

[0038] The process begins with arranging workpieces 20a and 20b in the joint and welding them together at the joint to form a welded joint 24. In the exemplary embodiment, the welding operation is a MIG welding operation; however, other known welding operations (such as laser welding) may also be used. Figure 4 As shown, in many cases, the weld joint 24 formed by the welding operation will include one or more silicate islands 26. As discussed in further detail below, during the finishing operation, some material of the weld joint 24 is removed from the weld joint 24 by a laser ablation process to remove the silicate islands 26.

[0039] Return to reference Figure 1 In an exemplary embodiment, workpieces 20a and 20b are welded together in a butt-joint manner. Workpieces 20a and 20b may be spaced approximately 0.4 mm apart before the welding operation. In some embodiments, workpieces 20a and 20b may be joined together with any suitable type of weld joint 24, including, for example, edge joints, corner joints, T-joints, lap joints, etc. Workpieces 20a and 20b are made of steel or other metals. In an exemplary embodiment, workpieces 20a and 20b form automotive parts, such as vehicle frames or vehicle brackets, and may have any suitable thickness. In an exemplary embodiment, workpieces 20a and 20b are, for example, components of a vehicle frame for a light truck. However, workpieces 20a and 20b may be used in other vehicle components or in other industries. It should be understood that the term "steel" as used herein means including alloy steel.

[0040] To remove the silicate islands 26 from the weld joint 24, the laser cleaning operation involves firing a laser beam 30 directly from a laser head 32 (sometimes referred to as a 2D scanner) onto the top (outer) surface of the weld joint 24 to remove material from the top layer of the weld joint 24 via an ablation process. Specifically, the laser beam 30 is pulsed at a specific frequency, predetermined power, and predetermined wavelength, causing all or most of the material of the silicate islands 26, along with any dust and oxides, to sublimate without removing any material surrounding the silicate islands 26 from the weld joint 24. This process has been found to allow silicate islands up to 0.1 mm in diameter to be completely or substantially completely removed from the weld joint 24. Figure 5 An exemplary weld joint 24 has been cleaned to remove and / or reduce the size of the silicate islands 26. In one example, a laser beam with a power of 1 kW to 2 kW and traveling along the weld at a speed of 5 mm / s to 35 mm / s has been found to be particularly effective in removing the silicate islands 26 and to cause minimal (if any) damage to the surrounding portion of the weld joint 24.

[0041] Now refer to Figure 6 The laser head 32 preferably includes a swing head that automatically controls the emission of the laser beam 30 to control the ablation process. The laser head 32 is mounted at the end of a six-axis robotic arm 34, which can manipulate the laser head 32 around workpieces 20a and 20b to clean weld joints 24 that may be difficult to reach using conventional cleaning techniques. During operation, the laser beam 30 sweeps across the entire weld joint 24, including both the silicate islands 26 and the material surrounding the silicate islands 26.

[0042] Another aspect of this disclosure relates to a manufacturing assembly line including a laser ablation station configured to remove silicate islands from pre-formed weld joints prior to the application of a phosphate coating. Figure 7 and Figure 8In the exemplary embodiment shown, a pair of laser cleaning assemblies 36 (each laser cleaning assembly including a robotic arm 34 and a laser head 32) are arranged in a well-ventilated and filtered cleaning workspace 38, which is part of an automotive assembly line. In operation, a part 22 to be cleaned (such as a vehicle frame or a portion thereof) enters the cleaning workspace 38 on a track and is guided to one or both laser cleaning assemblies 36. A controller guides the laser head 32 and robotic arm 34 through pre-programmed operations to clean the entire outer surface of multiple weld joints 24 on the part 22. The laser cleaning assemblies 36 can operate simultaneously to clean all or only some of the weld joints 24 on a single part 22, or the laser cleaning assemblies 36 can operate on different parts 22. In other embodiments, the workspace 38 may include only a single laser cleaning assembly 36, or the workspace 38 may include three or more laser cleaning assemblies 36. Figure 7 In this embodiment, the weld joint 24 is cleaned before the two halves of the vehicle frame are joined together, while Figure 8 In one embodiment, the welded joint 24 is cleaned after the frame assembly is completed.

[0043] In some embodiments, the laser cleaning assembly 36 can be configured to clean welded joints 24 on different types of parts 22—e.g., vehicle frames of different lengths—that have different numbers or locations of welds. To achieve this, a controller for the laser cleaning assembly 36 is configured to detect or otherwise determine which type of part 22 enters the workspace 38. Each type of part 22 can be associated with a unique operating procedure, which may include robotic arm movement, laser beam power, laser beam wavelength, and laser beam pulse frequency. Thus, when a first type of part 22 enters the workspace 38, the laser cleaning assembly 36 will operate according to a corresponding first operating procedure, and when a second type of part 22 enters the workspace 38, the laser cleaning assembly 36 will operate according to a corresponding second operating procedure. Therefore, the laser cleaning assembly 36 can be used to clean welded joints 24 on assembly lines producing different products.

[0044] Laser cleaning has been found to be faster, less expensive, and more reliable than other known finishing processes for removing silicate islands. Manual brushing (mechanical grinding), shot peening, or chemical treatments are not required to remove silicate islands 26 from weld joints 24.

[0045] Now refer to Figure 2Once the finishing operation is complete, the method proceeds to the step of applying a phosphate coating 28 to the component 22, including applying it to the entire weld joint 24. Due to the laser cleaning operation, the weld joint 24 has no silicate islands 26 or the silicate islands 26 are very small, thus having minimal impact on the bond strength between the component 22 and the phosphate coating 28. Therefore, the bond between the phosphate coating 28 and the metal material of the weld joint 24 is very strong compared to the portions of the weld joint where the silicate islands were not removed. Figure 3 As shown, an additional layer 40, such as an electrophoretic coating or a paint layer, is then applied on top of the phosphate layer 28. Depending on the application of component 22, other types of coatings may also be applied to the phosphate coating 28.

[0046] Obviously, based on the foregoing teachings, many modifications and variations of the invention are possible and can be practiced in ways different from those specifically described within the scope of the appended claims.

Claims

1. A method for manufacturing a component, the method comprising the following steps: Welding at least two workpieces together to form a weld joint including at least one silicate island; and After the at least two workpieces are welded together, the weld joint is laser-cleaned to remove all or most of the material of the at least one silicate island from the top surface of the weld joint, without removing any material surrounding the at least one silicate island. in, The laser beam used for laser cleaning has a power of 1 kW to 2 kW, and The laser beam moves along the top surface of the welded joint at a rate of 5 to 35 millimeters per second.

2. The method for manufacturing a component according to claim 1, wherein, The laser cleaning step does not remove the material surrounding the at least one silicate island at the weld joint.

3. The method for manufacturing a component according to claim 2, wherein, The laser cleaning step includes guiding a laser beam onto the entire top surface of the weld joint, which includes both the material surrounding the at least one silicate island and the weld joint.

4. The method of claim 1, further comprising the step of applying a phosphate layer to the weld joint after the step of laser cleaning the weld joint.

5. The method of claim 4, further comprising the step of applying a coating onto the phosphate layer.

6. The method according to claim 5, wherein, The coating is an electrophoretic coating or a paint layer.

7. The method according to claim 1, wherein, The step of laser cleaning the welded joint includes directing a pulsed laser beam from a laser head directly onto the top surface of the welded joint.

8. The method according to claim 7, wherein, The laser head is attached to the end of the robotic arm.

9. A method for manufacturing a component, the method comprising the following steps: Prepare a component comprising at least one welded joint having at least one silicate island; The laser beam is directly guided to the top surface of at least one of the welded joints; as well as The laser beam is used to remove all or most of the material of the at least one silicate island from the top surface of the at least one welded joint, without removing the material surrounding the at least one silicate island. The laser beam has a power of 1 kW to 2 kW, and The laser beam moves along the top surface of the welded joint at a rate of 5 to 35 millimeters per second.

10. The method according to claim 9, wherein, The laser beam is emitted from a laser head located at the end of the robotic arm.

11. A component comprising: At least two metal parts, said at least two parts being joined together at a welded joint, said welded joint being formed according to a welding process including the following steps; Welding at least two workpieces together to form a weld joint including at least one silicate island; and The weld joint is laser-cleaned to remove all or most of the material of the at least one silicate island from the top surface of the weld joint, without removing any material surrounding the at least one silicate island. The laser beam used for laser cleaning has a power of 1 kW to 2 kW, and The laser beam moves along the top surface of the welded joint at a rate of 5 to 35 millimeters per second.

12. The component according to claim 11, wherein, A phosphate layer is provided on the welded joint.

13. The component according to claim 12, wherein, A coating is provided on the phosphate layer.

14. The component according to claim 12, wherein, The forming process also includes directly guiding a pulsed laser beam from a laser head onto the top surface of the weld joint.

15. The component according to claim 11, wherein, The at least two components are made of steel or alloy steel.

16. The component according to claim 11, wherein, During the laser cleaning step, the material surrounding the at least one silicate island at the weld joint is not removed from the weld joint.

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