A roll welding forming method for a pre-galvanized layer profile

Abstract

The application discloses a roll welding forming method of a pre-plated zinc layer profile, and comprises the following steps: forming a first welding flange and a second welding flange by oppositely rolling and bending the edges of the plate on both sides; forming a first polishing space by continuously positively rolling and bending the plate area on one side of the first welding flange; polishing and removing zinc from the opposite sides in the first polishing space; forming a first cavity structure by continuously positively rolling and bending the plate area on one side of the first welding flange, and injecting a first welding laser; forming a second polishing space by continuously oppositely rolling and bending the plate area on one side of the second welding flange; polishing and removing zinc from the opposite sides in the second polishing space; forming a second cavity structure by continuously oppositely rolling and bending the plate area on one side of the second welding flange, and injecting a second welding laser; the application can remove the zinc layer in the welding area, reduce the zinc vapor generated during welding, and make the zinc vapor generated during welding overflow from both sides of the welding seam, thereby avoiding porosity defects.

Description

Technical Field

[0001] The present invention belongs to the technical field of roll-formed profiles, and relates to a roll-welding forming method for pre-galvanized layer profiles. Background Art

[0002] Pre-galvanized sheets (i.e., steel sheets pre-treated by hot-dip galvanizing or electro-galvanizing) are widely used in the automotive, energy, construction and other fields due to their excellent corrosion resistance. The hollow tube with a "日"-shaped cross-section is often used for structural parts such as the frame border of battery trays because of its large section modulus and high load-bearing capacity.

[0003] The continuous roll forming process is the mainstream conventional solution for manufacturing the "日"-shaped cross-section tube, which forms the pre-galvanized sheet into a preset cross-section through multi-pass rolling or die bending, and then seals the seam by high-frequency welding, argon arc welding and other methods. Its principle is to realize cross-section forming by gradual accumulation of plastic deformation of metal.

[0004] In the prior art, the Chinese invention patent with publication number CN121339660A specifically discloses a method for manufacturing high-strength automotive "日"-shaped parts based on laser roll forming, in which laser filler wire fusion welding is directly adopted at two joints 4 to form a closed "日"-shaped tube; however, for pre-galvanized sheets, the boiling point of zinc (about 907°C) is much lower than the melting point of steel (about 1500°C). Before the steel is melted, the zinc layer has already reached the gasification temperature (about 907°C), and a large amount of zinc vapor overflows from the molten pool, disturbing the molten pool, resulting in pores and spatter in the weld seam, which makes the welding quality difficult to guarantee; The patent document with publication number CN102922817A discloses a galvanized sheet for laser lap welding and its welding process, which belongs to the technical field of automotive body-in-white laser processing. In this method, the upper steel plate composite is placed in a die, and after stamping by the die, two rows of regularly arranged protrusions with consistent depth are formed; the upper steel plate composite is arranged above the lower steel plate composite; the protrusions on the upper steel plate composite are in contact with the second upper galvanized layer on the lower steel plate composite; before the laser welding starts, the laser focus is moved to the center of the two rows of protrusions on the front side. When welding starts, zinc gas stably overflows through the overflow channels reserved by the protrusions between the upper steel plate composite and the lower steel plate composite, and the required product is obtained after welding. However, the workpiece welded by the above technical solution is stationary during the welding process, and is not suitable for the continuous roll forming process.

[0005] Therefore, in order to solve the above technical problems, there is an urgent need for a roll-welding forming method for pre-galvanized layer profiles that improves welding quality. Contents of the Invention

[0006] The present invention proposes a roll-welding forming method for pre-galvanized layer profiles, which well solves the problems in the prior art.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a roll forming method for pre-galvanized profiles, comprising the following steps: Step S100: The edges of both sides of the sheet metal are bent by reverse roller pressing to form the first welding flange and the second welding flange; Step S200: Continuously forward roll bending the sheet metal area on one side of the first welded flange, forming a first grinding space between the first welded flange and the middle area of ​​the sheet metal; Step S300: Grind and remove zinc from the side opposite to the first welding flange and the middle area of ​​the sheet metal within the first grinding space; Step S400: Continue to roll-bend the sheet metal area on one side of the first welding flange so that the first welding flange and the side of the sheet metal are in contact to form the first cavity structure, and apply the first welding laser to the contact position. Step S500: Continuously reverse roll bending the sheet area on one side of the second welding flange to form a second grinding space between the second welding flange and the side wall of the opposite first cavity structure; Step S600: Grind and remove zinc from the side surfaces opposite to the sidewalls of the second welding flange and the first cavity structure within the second grinding space; Step S700: Continue to reverse roll bend the sheet area on one side of the second welding flange, so that the second welding flange and the side wall surface of the first cavity structure are attached to form the second cavity structure, and a second welding laser is applied to the attachment position.

[0008] Furthermore, it also includes the following steps: Step S110: Forward roll bending of the middle area of ​​the sheet metal, bending it at 10° to 15°; Step S410: The middle area of ​​the sheet metal after reverse roller bending is restored to the shape before forward bending in step S110.

[0009] Furthermore, in step S400, the incident angle of the first welding laser is 0 to 15°, and the formed weld completely passes through the first welding flange.

[0010] Furthermore, in step S700, the incident angle of the second welding laser is -10° to 10°, and the formed weld completely passes through the second welding flange.

[0011] Furthermore, the first welding laser and the second welding laser are tilted at an angle in the direction of sheet travel, so that the laser spot forms an ellipse at the welding position; wherein, the tilt angle is set at 10° to 15° with the vertical direction as the center.

[0012] Furthermore, hot air is provided upstream of the positions of the first and second welding lasers in the sheet metal travel direction, blowing towards the first and second welding flanges, with the hot air temperature being 200℃~400℃.

[0013] Further, in step S100, the lengths of the first welding flange and the second welding flange are t to 2t, where t is the thickness of the sheet metal.

[0014] Furthermore, in steps S300 and S600, a thin grinding wheel is used to grind and remove zinc.

[0015] Furthermore, the thin grinding wheel used in steps S300 and S600 is provided with a first grinding surface and a second grinding surface on both sides respectively; the grinding width covered by the first grinding surface and the second grinding surface is greater than the length of the first welding flange or the second welding flange.

[0016] Furthermore, the distance between the thin grinding wheel and the incident position of the first or second welding laser is between 300 and 1000 mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects: In this invention, by controlling the lengths of the first and second welding flanges, and the incident angles of the first and second welding lasers, the weld produced during welding can completely penetrate the first or second welding flange, and the molten pool forms a through channel between the laser incident end and the laser exit end, allowing zinc vapor to overflow from both sides simultaneously, effectively avoiding porosity defects. In this invention, by forming a first grinding space and a second grinding space during the rolling process, and by effectively removing the zinc layer on the surface of the sheet metal in the welding area before welding, the zinc vapor generated during welding is reduced. In this invention, the distance between the thin grinding wheel and the incident position of the first or second welding laser is between 300 and 1000 mm; the material conveying distance from the zinc removal to the laser welding position is minimized, cutting off the path of secondary contamination in both time and space, and ensuring that the clean area after zinc removal is not contaminated by zinc shavings in the environment before welding. In this invention, by reverse roll forming the middle area of ​​the sheet metal, the cross-sectional stiffness of the sheet metal plane area is increased during the roll forming process, the generation of waves is suppressed, and the roll forming process is made more stable, thereby improving the consistency of the welding process. In this invention, the first and second welding lasers are tilted at an angle in the direction of sheet travel, so that the laser spot forms an ellipse at the welding position. This not only provides a time window for zinc vapor to fully overflow, but also forms a preheating zone at the front end of the ellipse, reducing the amount of zinc vapor bursting at the moment of welding. Attached Figure Description

[0018] Figure 1 This refers to the cross-sectional shape of the sheet metal after roll forming and welding in this invention; Figure 2 This is a schematic diagram of the reverse bending of the middle area of ​​the sheet metal in this invention; Figure 3 This is a state diagram of the thin-blade grinding wheel grinding the first grinding space in this invention; Figure 4 This is a state diagram of the thin-blade grinding wheel grinding the second grinding space in this invention; Figure 5 This is a schematic diagram of the sheet metal roller bending process in this invention; Figure 6 This is a schematic diagram of the interaction between the thin grinding wheel and the first grinding space in this invention.

[0019] In the figure: 1. First welding flange; 2. Second welding flange; 3. First cavity structure; 4. Second cavity structure; 5. First grinding surface; 6. Second grinding surface; 7. Thin grinding wheel; 8. First grinding space; 9. Second grinding space. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1:

[0021] like Figure 1 As shown, this invention proposes a roll forming method for a pre-galvanized profile, wherein the profile is a H-shaped tube profile, and includes the following steps: Step S100: The edges of both sides of the sheet metal are bent by reverse roll forming to form a first welded flange 1 and a second welded flange 2; wherein reverse roll forming refers to... Figure 5 In the cross-sectional view of the profile shown, the sheet metal is bent counterclockwise; while the forward roll bending described below refers to the cross-sectional view of the profile where the sheet metal is bent clockwise. Step S200: Continuously forward roll bending of the sheet metal area on one side of the first welded flange 1, forming a first grinding space 8 between the first welded flange 1 and the middle area of ​​the sheet metal; specifically, as follows... Figure 5 As shown, the left side of the sheet metal is first bent into two right angles, so that the left side of the sheet metal is bent towards the middle area, and then an obtuse angle is formed. The first welding flange 1 on the left side of the sheet metal is close to the surface of the middle area of ​​the sheet metal, at which point the first grinding space 8 is formed. Step S300: Grind and remove zinc from the side opposite to the first welding flange 1 and the middle area of ​​the sheet metal within the first grinding space 8; Step S400: Continue forward roll bending of the sheet metal area on one side of the first welding flange 1, so that the first welding flange 1 and the side of the sheet metal are in contact, forming the first cavity structure 3, and the first welding laser is applied to the contact position; specifically, continue forward roll bending at the obtuse angle position formed in step S200 to form a third right angle, so that the first cavity structure 3 is formed into a square shape; after the first welding laser is applied to the contact position, the first weld is formed at the position of the first welding flange 1; Step S500: Continuously reverse roll bending of the sheet metal area on one side of the second welded flange 2, forming a second grinding space 9 between the second welded flange 2 and the side wall of the opposite first cavity structure 3; specifically, as shown... Figure 5 As shown, the right side of the sheet is first bent into a right angle, so that the right side of the sheet is bent toward the middle area, and then bent again to form an obtuse angle. The second welding flange 2 on the right side of the sheet is close to the surface of the middle area of ​​the sheet, thus forming the second grinding space 9. Step S600: Grind and remove zinc from the opposite sides of the second welding flange 2 and the sidewall of the first cavity structure 3 within the second grinding space 9; Step S700: Continue reverse roll bending of the sheet material area on one side of the second welding flange 2, so that the second welding flange 2 and the side wall surface of the first cavity structure 3 are attached to form the second cavity structure 4, and the second welding laser is applied to the attachment position; specifically, the obtuse angle position formed in step S500 is further reverse roll bent to form a second right angle, so that the second cavity structure 4 is also in the shape of a "U". After the second welding laser is applied to the attachment position, a second weld is formed on the second welding flange 2; finally, the sheet material is formed into a "H" shaped tube profile.

[0022] In this embodiment, in step S100, the lengths of the first welding flange 1 and the second welding flange 2 are t to 2t, where t is the thickness of the sheet metal. Furthermore, in step S400, the incident angle of the first welding laser is 0 to 15°, and the formed weld completely passes through the first welding flange 1. Within the incident angle range of 0 to 15°, it can be ensured that the weld formed by the laser penetration can pass through the first welding flange 1. The molten pool at the first welding flange 1 forms a through-channel between the laser incident end and the laser exit end, effectively ejecting the molten zinc layer at the welding position. Zinc vapor can simultaneously overflow from both ends of the through-channel, significantly improving venting efficiency and preventing zinc vapor from stagnating inside the molten pool and forming pores, effectively avoiding pore defects. Similarly, in step S700, the incident angle of the second welding laser is -10° to 10°, and the formed weld completely passes through the second welding flange 2, ensuring the quality of the weld formed by the second welding laser. The shielding gas during welding is nitrogen, and the focal length is set to 296 to 302 mm.

[0023] In this embodiment, the first and second welding lasers are tilted at an angle in the sheet metal traveling direction, so that the laser spot forms an ellipse at the welding position. The tilt angle is set at 5° to 15° with the vertical direction as the center. Specifically, the laser incident can be tilted upstream or downstream in the sheet metal traveling direction. The elliptical laser spot can lengthen the molten pool during welding, and the solidification time of the molten pool can be extended by 30% to 50%, providing a time window for the zinc vapor to fully escape. Furthermore, the front end of the elliptical laser spot (i.e., the part irradiating upstream of the sheet metal) heats the sheet metal first, forming a preheating zone, so that the residual zinc layer on the first welding flange 1 and the corresponding side of the sheet metal reaches the volatilization temperature in advance, reducing the amount of zinc vapor burst at the moment of welding. At the same time, preheating reduces the thermal shock gradient during welding, the molten pool flows more smoothly, reduces welding spatter, and reduces the risk of weld slag falling on the sheet metal surface and forming indentation defects after subsequent rolling.

[0024] Preferably, hot air is provided upstream of the positions of the first and second welding lasers in the sheet metal travel direction, blowing towards the first welding flange 1 and the second welding flange 2. The hot air temperature is 200-400℃. This preheats the sheet metal area where the first welding flange 1 and the second welding flange 2 are located, ensuring the preheating effect of the subsequent laser spot and also blowing away impurities present in the welding area. Specifically, a hot air gun can be set up upstream of the positions of the first and second welding lasers in the sheet metal travel direction. The hot air gun blows directly onto the first welding flange 1 and the second welding flange 2, and the distance between the hot air gun and the air outlet is maintained at 3-10mm to generate continuous hot air.

[0025] In this embodiment, a thin grinding wheel 7 is used for grinding and zinc removal in steps S300 and S600; specifically, the thickness of the thin grinding wheel 7 is 5-10mm. In step S300, the grinding surfaces on both sides of the thin grinding wheel 7 can touch the two opposite sides of the first welding flange 1 and the middle area of ​​the sheet in the first grinding space 8; in step S600, the grinding surfaces on both sides of the thin grinding wheel 7 can touch the two opposite sides of the second welding flange 2 and the side wall of the first cavity structure 3 in the second grinding space 9, thereby completing the grinding of the zinc layer at the corresponding positions in the first grinding space 8 and the second grinding space 9, removing most of the zinc layer before laser welding, and reducing the zinc vapor generated during welding; Specifically, two thin grinding wheels 7 can be set in both the first grinding space 8 and the second grinding space 9. The two thin grinding wheels 7 are set sequentially according to the direction of profile travel, and the inclination angle of the thin grinding wheels 7 is adapted to the positions of the opposite sides in the first grinding space 8 and the second grinding space 9. During the profile rolling process, the opposite sides in the first grinding space 8 or the second grinding space 9 continuously approach and contact the grinding surface of the thin grinding wheels 7, and the opposite sides in the first grinding space 8 or the second grinding space 9 are ground and zinc removed sequentially by the grinding surfaces of the two thin grinding wheels 7.

[0026] Optional, such as Figure 6 As shown, an annular protrusion is formed on the outer edge of the thin grinding wheel 7, with a protrusion height of 0.05 to 0.15 mm. After grinding the sheet surface of the first grinding space 8 and the second grinding space 9, a groove can be formed on the sheet side wall opposite the first welding flange 1 or the second welding flange 2 to provide an additional escape space for zinc vapor to escape during laser welding. Example 2:

[0027] The difference compared to the above embodiments is as follows: Figure 2 as well as Figure 5 As shown, in addition to the steps implemented in Embodiment 1 above, the following steps are also included: Step S110: Forward roll bending of the middle area of ​​the sheet metal, bending it at 10° to 15°; Step S410: The middle area of ​​the reverse roller-bent sheet material is restored to the shape before the forward bending in step S110; Specifically, in step S110, the area on the right side of the middle of the bent sheet is bent so that the bent area is not located within the forming area of ​​the first cavity structure 3. The bent area formed during the roll forming process serves two purposes: firstly, it provides sufficient incident space for the first welding laser, and also provides sufficient clearance for the grinding tools in the first grinding space 8; secondly, it increases the cross-sectional stiffness of the right side plane of the sheet, suppresses wave generation, and makes the roll forming process more stable, thereby providing consistency in the welding process. Example 3:

[0028] The difference compared to the above embodiments is as follows: Figure 3 As shown, a portion of the thin grinding wheel 7 ( Figure 3 The dotted line portion (in the image) is located in the first grinding space 8. The thin grinding wheel 7 is generally annular. A first grinding surface 5 and a second grinding surface 6 are respectively provided on both sides of the thin grinding wheel 7 used in step S300. The grinding width covered by the first grinding surface 5 and the second grinding surface 6 is greater than the length of the first welding flange 1; specifically, as shown... Figure 3 As shown, a neutral surface (indicated by the dotted line in the figure) is provided on the thin grinding wheel 7. The first grinding surface 5 and the second grinding surface 6 are inclined at an angle of 5° to 10° relative to the neutral surface. During the rolling process of the sheet metal, the first welding flange 1 corresponding to the first grinding space 8 moves towards the first grinding surface 5, and the side of the corresponding middle area of ​​the sheet metal moves towards the second grinding surface 6 to remove zinc. When the thin grinding wheel 7 grinds the first grinding space 8, the first grinding surface 5 is flush with the first welding flange 1, and the second grinding surface 6 is flush with the side of the middle area of ​​the sheet metal. The thin grinding wheel 7 is driven to rotate by an external motor. This makes the zinc removal position close to the first welding laser incident position, which can effectively remove the zinc layer and also prevent the debris generated during the long rolling process from re-entering the welding position, thus improving the quality of the weld. Similarly, such as Figure 4 As shown, the thin-blade grinding wheel 7 used in step S600 can also be configured with a first grinding surface 5 and a second grinding surface 6. The first grinding surface 5 and the second grinding surface 6 are also configured with an inclination angle of 5° to 10°, as detailed below. Figure 4 The dotted lines in the diagram indicate that the inclination angles of the first grinding surface 5 and the second grinding surface 6 in the thin-blade grinding wheel 7 used in step S600 may differ from those in step S300, and can be adapted according to specific usage. When the thin-blade grinding wheel 7 grinds the second grinding space 9, the first grinding surface 5 is flush with the second welding flange 2, and the second grinding surface 6 is flush with the side of the side wall of the first cavity structure 3. The thin-blade grinding wheel 7 is driven to rotate by an external motor. During the rolling process of the sheet metal, the corresponding second welding flange 2 in the second grinding space 9 approaches and contacts the first grinding surface 5, and the side of the side wall of the first cavity structure 3 approaches the second grinding surface 6, thus removing zinc. Therefore, it can be ensured that the zinc layer at the grinding location is ground evenly, improving the quality of zinc layer removal.

[0029] It should be noted that the angle at which the thin grinding wheel 7 is placed in steps S300 and S600 is adapted to the angle of the first grinding space 8 and the second grinding space 9, so that the first grinding surface 5 and the second grinding surface 6 can contact the side zinc layer to be ground; specifically, the opening angle of the first grinding space 8 and the second grinding space 9 can be set to 20° to 30°.

[0030] In this embodiment, the distance between the thin grinding wheel 7 and the incident position of the first or second welding laser is between 300 and 1000 mm; this minimizes the sheet metal conveying distance from the zinc removal stage to the laser welding position, cutting off the path of secondary contamination in both time and space, and ensuring that the clean area after zinc removal is not contaminated by zinc shavings in the environment before welding. Furthermore, the use of the thin grinding wheel 7 provides significant continuous production stability for the roll forming process.

[0031] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A roll forming method for pre-galvanized profiles, characterized in that, Includes the following steps: Step S100: The edges of both sides of the sheet metal are bent by reverse roller pressing to form the first welded flange (1) and the second welded flange (2). Step S200: Continuously roll bend the sheet area on one side of the first welded flange (1) to form a first grinding space (8) between the first welded flange (1) and the middle area of ​​the sheet. Step S300: Grind and remove zinc from the first welding flange (1) and the side opposite to the middle area of ​​the plate in the first grinding space (8); Step S400: Continue to roll-bend the sheet area on one side of the first welding flange (1) so that the first welding flange (1) and the side of the sheet are attached to form the first cavity structure (3), and the first welding laser is applied to the attachment position; Step S500: Continuously reverse roll bending the sheet area on one side of the second welding flange (2) to form a second grinding space (9) between the second welding flange (2) and the side wall of the opposite first cavity structure (3). Step S600: Grind and remove zinc from the opposite sides of the second welding flange (2) and the sidewall of the first cavity structure (3) in the second grinding space (9); Step S700: Continue to reverse roll bend the sheet area on one side of the second welding flange (2) so that the second welding flange (2) and the side wall surface of the first cavity structure (3) are attached to form the second cavity structure (4), and a second welding laser is applied to the attachment position.

2. The roll forming method for pre-galvanized profiles according to claim 1, characterized in that, It also includes the following steps: Step S110: Forward roll bending of the middle area of ​​the sheet metal, bending it at 10° to 15°; Step S410: The middle area of ​​the sheet metal after reverse roller bending is restored to the shape before forward bending in step S110.

3. The roll forming method for pre-galvanized profiles according to claim 1, characterized in that, In step S400, the incident angle of the first welding laser is 0 to 15°, and the formed weld completely passes through the first welding flange (1).

4. The roll forming method for pre-galvanized profiles according to claim 3, characterized in that, In step S700, the incident angle of the second welding laser is -10° to 10°, and the formed weld completely passes through the second welding flange (2).

5. The roll forming method for pre-galvanized profiles according to claim 4, characterized in that, The first and second welding lasers are tilted at an angle in the direction of sheet material travel, so that the laser spot forms an ellipse at the welding position; wherein the tilt angle is set at 5° to 15° with the vertical direction as the center.

6. The roll forming method for pre-galvanized profiles according to claim 5, characterized in that, Hot air is provided upstream of the first welding laser and the second welding laser in the direction of sheet travel, blowing towards the first welding flange (1) and the second welding flange (2), with a hot air temperature of 200℃~400℃.

7. The roll forming method for pre-galvanized profiles according to claim 1, characterized in that, In step S100, the lengths of the first welding flange (1) and the second welding flange (2) are t to 2t, where t is the thickness of the sheet metal.

8. The roll forming method for pre-galvanized profiles according to claim 1, characterized in that, In steps S300 and S600, a thin grinding wheel (7) is used to grind and remove zinc.

9. The roll forming method for pre-galvanized profiles according to claim 8, characterized in that: The thin grinding wheel (7) used in steps S300 and S600 is provided with a first grinding surface (5) and a second grinding surface (6) on both sides respectively; the grinding width covered by the first grinding surface (5) and the second grinding surface (6) is greater than the length of the first welding flange (1) or the second welding flange (2).

10. The roll forming method for pre-galvanized profiles according to claim 8, characterized in that: The distance between the thin grinding wheel (7) and the incident position of the first or second welding laser is between 300 and 1000 mm.

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