WO2025221480A1

WO2025221480A1 - Method and apparatuses for mash seam welding in steel making

Info

Publication number: WO2025221480A1
Application number: PCT/US2025/023116
Authority: WO
Inventors: Hao GUO
Original assignee: Cleveland Cliffs Steel Properties Inc
Current assignee: Cleveland Cliffs Steel Properties Inc
Priority date: 2024-04-19
Filing date: 2025-04-04
Publication date: 2025-10-23
Anticipated expiration: 2026-10-19

Abstract

The present invention relates to a method and apparatus for mash welding in steel making, wherein a step of brushing the overlapping areas of sheet metal surfaces (102, 108) before the mash seam welding process of the pair of steel sheets (100, 106) is provided in order to give the surfaces (102, 108) of the overlapping areas increased surface roughness. The apparatus as well is using such application of brushing and mash seam welding. This ultimately results in steel products with greater weld strength, especially for high-strength steels.

Description

METHOD AND APPARATUSES FOR MASH SEAM WELDING IN STEEL MAKING

PRIORITY

[0001] This application claims priority to U.S. Provisional Application Serial No. 63/636,237, entitled “Method to Increase the Mash Seam Welding Strength of Sheet Metals,” filed on April 19, 2024, the disclosure of which is incorporated by reference herein.

BACKGROUND

[0002] In steelmaking, mash seam welding is a variant of resistance seam welding in which steel sheets are overlapped by a distance. In some circumstances, the distance of overlap may be about 1.5 times the sheet thickness. The overlapping of the steel sheets results in the formation of a crevice between the steel sheets. During welding, the steel is compressed to a final thickness, which may be, for example, about 1.4 times the sheet thickness. The welding is performed using opposing wheel electrodes positioned on each side of the steel sheets. Some melting occurs, but the edges of the joint form a solid phase bond to eliminate the crevice.

[0003] Examples of various material processing operations are disclosed in KR No. 20080105948A, entitled “Roll-Formed Mash Seam Welding Method and Device of Metallic Plates,” Published on October 31, 2007; KR No. 20070105951A, entitled “Exrtu-Rolled Mash Seam Welding Method and Device of Metallic Plates,” published on October 31, 2007; and KR No. KR100897680B1, entitled “Extru-Rolled Mash Seam Welding Method and Device of Metallic Plates,” published on May 14, 2014.

[0004] In some circumstances, mash seam welding of advanced high-strength steels may have certain challenges. For instance, low weld quality may cause weld breaks and significant amount of production downtime. Grinding rollers or planish wheels have been used to remove surface oxides or pre-compress the base metal strips to break the surface oxide layer, but these techniques fail to create localized deformation and/or localized breakage of the oxide layer. As a result, weld quality issues may persist.

DESCRIPTION OF DRAWINGS [0005] While the specification concludes with claims which particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying examples and figures.

[0006] FIG. 1 shows a perspective view of a pair of steel sheets, each steel sheet including an overlapping area.

[0007] FIG. 2 shows a top plan view of one of the pair of steel sheets from FIG. 1 after the overlapping area of each steel sheet has been brushed, giving the overlapping area of each steel sheet an increased surface roughness.

[0008] FIG. 3 shows a side elevational view of the pair of steel sheets of FIG. 1 being overlapped, with the pair of steel sheets in contact at the overlapping area.

[0009] FIG. 4 shows a side plan view of a pair of steel sheets being subjected to a welding sequence.

[0010] The figures are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways. The accompanying figures incorporated in and forming a part of the specification show aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to what is shown in the figures.

DETAILED DESCRIPTION

[0011] The following description of certain examples of the invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the invention will become apparent to those skilled in the art from the following description. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the examples, figures, and descriptions should be regarded as illustrative in nature and not restrictive. [0012] The following description details a method for increasing the surface roughness of the overlapping area of sheet metal before the mash seam welding process. During the mash seam welding process, a continuous seam between a pair of steel sheets is formed. In some contexts, mash seam welding of advanced high-strength steels may have certain challenges. For instance, the procedure of mash seam welding applied to advanced high-strength steel may result in inconsistent or low weld quality due to the presence of an oxide layer, poor material contact, or combinations thereof. Such challenges may lead to weld breaks and a significant amount of production downtime. Such challenges may increase as newer steels of higher strengths are developed.

[0013] In some circumstances, improved weld quality can be achieved using localized deformation of base material sheet metal prior to mash seam welding. This deformation can include a method of brushing the overlapping area of sheet metal before the steel undergoes mash seam welding. This brushing may increase localized metal deformation, facilitate surface oxides layer break, or facilitate the base metal contact between the two strips. The brushing may be performed by a surfacing device (also referred to as an abrasion device or abrator or scrubbing device or polishing device). The area of the steel that undergoes brushing treatment is limited to the surface area of each steel that is to be overlapped during the mash seam welding process. The surface area of the steel that will not be overlapped, in contrast, does not receive any brushing treatment. This results in the surface of the overlapping area of the sheet metal having a greater surface roughness than the surface of the steel that does not overlap.

[0014] The surface roughness of the overlapping areas of metal sheets after undergoing such brushing can include certain surface roughness characteristics. Subsequent mash seam welding of metal sheets that has undergone brushing at the surface of the overlapping areas will produce a welded steel product with superior weld strength. These benefits are especially notable with high-strength base metals. By restricting the area of the sheet metal being brushed to only the overlapping area, unwanted stress concentration is avoided. [0015] The following examples describe different alternatives to the surfacing device. These examples may be mutually exclusive of each other, but also may be used in combination.

[0016] In some examples, the surfacing device includes stainless steel wire wheel brushes. In some examples, the brushes are rotary stainless steel wire wheel brushes. The grit rating of the wire brushes may vary as will be appreciated by those of ordinary skill in the art.

[0017] In other examples, the surfacing device includes rolling wheels with textured surfaces can be used to imprint a specific texture or desired indents on the surface of the overlapping area of the sheet metal. These imprinted textures may provide the same effect of increased surface roughness to the overlapping area of the sheet metal, and thus may provide the same benefits to the welded steel product.

[0018] It should be understood that in some examples, the surfacing device is optional and may be omitted. In lieu of, or in combination with, the surfacing device, other forms of material processing may be used. For instance, in some examples, the surface of the overlapping areas will undergo machining to scribe a surface texture in order to increase the surface roughness.

[0019] In still other examples, abrasive tools are used to increase the surface roughness of the overlapping areas of the sheets of metal.

[0020] FIG. 1 shows a pair of steel sheets (100, 106). Each sheet of the pair of steel sheets (100, 106) has a portion of sheet’s surface area that is an overlapping area (102, 108). The overlapping areas (102, 108) are the surfaces of the pair of steel sheets (100, 106) that are to come in contact with each other and overlay during the mash seam welding process. As can be seen in FIG. 1, the overlapping areas (102, 108) may be along the edge of each sheet of the pair of steel sheets (100, 106).

[0021] FIG. 2 shows one of the steel sheets (200) from a top plane view. As can be seen in FIG. 2, the surface of the overlapping area (202) of the steel sheet (200) has been modified. Specifically, the surface of the overlapping area (202) has been treated with a surfacing device (204) to give the surface of the overlapping area (202) an increased surface roughness. As can also be seen in FIG. 2, the entirety of the surface of the steel sheet (200) other than the overlapping area (202) has not been treated with a surfacing device to modify its surface roughness. In other words, the overlapping area (202) of the steel sheet (200) has a greater surface roughness than the rest of the steel sheet (200) because the overlapping area (202) has been treated with a surfacing device (204) and the rest of the steel sheet (200) has not.

[0022] The surfacing device (204) used to treat the overlapping area (202) may be an abrator or abrasion device. In some examples, the surfacing device (204) performs a brushing treatment on the overlapping area (204). In some examples, the surfacing device (204) includes stainless steel wire wheel brushes. In other examples, the surfacing device (204) includes rolling wheels with textured surfaces. These rolling wheels imprint a specific texture or desired indents on the surface of the overlapping area of the sheet metal. In still other examples, surfacing device (204) can be omitted and another form of treatment may be applied such as those described above (e.g., machining).

[0023] The steel sheets (200) may be advanced high strength steels. In some examples, the pair of steel sheets (200) may be the same grade. In other examples, each sheet of the pair of steel sheets (200) may be of a different grade.

[0024] FIG. 3 shows the pair of steel sheets (300, 306) from FIG. 1 after they have been overlapped for the mash seam welding process. As can be seen in FIG. 3, only the portions of the surfaces of the steel sheets (300, 306) that have been treated with tools to increase the surface roughness are overlapped, and are in contact on a plane (310). Every part of the surface of each steel sheet (300, 306) that is not overlapped have not been treated with brushing and have not had their surface roughness modified or increased.

[0025] FIG 4 shows a mash seam welding sequence, including a mash seam welding apparatus. The mesh seam welding apparatus includes a set of welding rollers (412, 414). The set of welding rollers (412, 414) are configured to engage the edges of two steel sheets. As shown in FIGS. 1 and 3, the two steel sheets are overlapped only at the surface areas that have been brushed, therefore having reduced surface roughness. No other parts of the steel sheets have been brushed. As the two steel sheets undergo mash seam welding, the two steel sheets are joined into one steel sheet (400).

[0026] In some examples, a heating element is positioned to heat the proximate edges of the steel sheets during welding. In other examples a control system controls the pressure applied by the welding apparatus and controls welding speed. In other examples, the two steel sheets are held in proximity by a frame. In other examples, the welding rollers are adjustable to accommodate varying sheet thickness and materials.

[0027] It should be understood that any one or more of the teachings, embodiments, examples, etc. described herein may be combined with any one or more of the other teachings, embodiments, examples, etc. that are described herein. The following-described teachings, embodiments, examples, etc. should therefore not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined will be readily apparent to those of ordinary skill in the art in view of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0028] Having shown and described various examples of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.

Claims

I/We claim:

1. A method for mash seam welding in steelmaking, comprising the steps of: a) providing a pair of steel sheets to be joined, wherein each sheet of the pair of steel sheets defines an overlapping surface; b) treating the overlapping surface of the pair of steel sheets via a surfacing device to increase surface roughness of the overlapping surface of the pair of steel sheets, wherein the treating includes only treating the overlapping surface without treating any other area of the pair of steel sheets; c) placing the pair of steel sheets in proximity to each other, wherein only the overlapping surface of the pair of steel sheets come in contact; d) applying a mash seam welding apparatus to an edge of each steel sheet of the pair of steel sheets; and e) initiating a welding process to form a continuous seam between the pair of steel sheets.

2. The method of claim 1, wherein the surfacing device treats the overlapping surface of the pair of steel sheets with one or more stainless steel wire wheel brushes.

3. The method of claim 2, wherein the stainless steel wire wheel brushes rotate.

4. The method of claim 1, wherein the surfacing device treats the overlapping surface of the pair of steel sheets with one or more rolling wheels.

5. The method of claim 4, wherein the one or more rolling wheels impart one or more indents on the surface of the overlapping surface of the pair of steel sheets.

6. The method of claim 5, wherein the one or more rolling wheels treat the overlapping surface with a textured surface on the one or more rolling wheels.

7. The method of claim 1, wherein the treating of the overlapping surface of the pair of steel sheets includes machining to scribe surface roughness to the overlapping surface.

8. The method of claim 1, wherein the mash seam welding apparatus includes a set of welding rollers to perform the treating of the overlapping surface of the pair of steel sheets.

9. The method of claim 1, wherein the welding process comprises: a) controlling the pressure applied by the welding apparatus to achieve a desired mash seam weld quality; and b) adjusting the welding speed to enhance the fusion of the pair of steel sheets.

10. An apparatus for mash seam welding in steelmaking, comprising: a) a pair of steel sheets, wherein each sheet of the pair of steel sheets defines an overlapping surface; b) a surfacing device, the surfacing device configured to increase surface roughness of the overlapping surface of the pair of steel sheets via brushing, wherein the surfacing device only brushes the overlapping surface without brushing any other area of the pair of steel sheets; and c) welding rollers.

11. The apparatus of claim 10, wherein the surfacing device includes one or more stainless steel wire wheel brushes.

12. The apparatus of claim 11 , wherein the stainless steel wire wheel brushes are rotary stainless steel wire brushes.

13. The apparatus of 10, wherein the surfacing device includes one or more rolling wheels.

14. The apparatus of claim 13, wherein the one or more rolling wheels are configured to impart one or more indents on the surface of the overlapping surface of the pair of steel sheets.

15. The apparatus of claim 14, wherein the one or more rolling wheels are configured to treat the overlapping surface with a textured surface on the one or more rolling wheels.

16. The apparatus of claim 10, wherein the surface device is configured to machine to scribe surface roughness to the overlapping surface.

17. The apparatus of claim 10, wherein the welding rollers are configured to engage the edges of the pair of steel sheets.

18. An apparatus for mash seam welding in steelmaking, comprising: a) a pair of steel sheets, wherein each sheet of the pair of steel sheets defines an overlapping surface, wherein the overlapping surface comprises a region of each sheet of the pair of steel sheets that is the width of the steel sheet and is the length of less than 36 inches. b) a surfacing device, the surfacing device configured to increase surface roughness of the overlapping surface of the pair of steel sheets via brushing, wherein the surfacing device only brushes the overlapping surface without brushing any other area of the pair of steel sheets; and c) welding rollers.