A method of edge covering

Abstract

The application discloses a covering process method, relates to the covering process technical field, and is applied to the covering connection of an outer plate and multiple inner plates. The covering process method comprises the following steps: obtaining an angle design range calculated according to an avoidance gap design value and an inner-outer plate lap amount; adjusting the side end of the inner plate splicing into a corresponding inclined angle according to the angle design range; folding the outer plate and covering the end of the inner plate, and then pressing by a roller. According to the technical scheme, the side end of the multiple inner plates is inclined, the occurrence of the roller air pressure is reduced without changing the design gap between the inner plates, specifically, the angle design range is calculated according to the avoidance gap design value and the inner-outer plate lap amount, the side end of the inner plate splicing is designed according to the obtained angle design range, and the vertical direction of the roller is supported by the inner plate, so that the problem that the stamping depression appears on the appearance surface after the covering pressing is solved.

Description

Technical Field

[0001] The invention relates to the field of hemming art, and in particular to a hemming process method. Background Art

[0002] The current automotive industry is experiencing rapid development in styling design. The design of the hemming connection structure for automotive sheet metal coverings, which is highly correlated with the exterior appearance, is a crucial step in the automotive manufacturing process, impacting the exterior quality and structural strength of the body-in-white (BIW). In the automotive manufacturing industry, a manufacturing-oriented design philosophy can minimize manufacturing costs, improve product quality, and shorten development cycles. Typically, the hemming connection structure design uses an hemming connection process to wrap the outer panel around the inner panel, or vice versa, forming a connection between the inner and outer panels and a secure part edge. For the same hemming section, especially in the exterior area, the hemming connection structure is designed as a continuous outer panel and inner panel connected as a whole. A complete inner panel hemming surface is essential to ensure a good hemming appearance.

[0003] For special inner panel shapes, it may be impossible to achieve one-piece stamping, and there may be problems such as excessive local stress, which can easily cause quality defects such as stretch cracking. The stamped inner panel needs to be cut into two or more sheet metal pieces to ensure good stamping formability, and then welded to form an inner panel assembly. If such a part is made with a conventional continuous hemming structure, the unavoidable gap between the inner panels at the connection point will cause obvious appearance quality defects at the corresponding position of the hemming surface due to the pressure of the hemming. Summary of the Invention

[0004] The main purpose of the present invention is to provide a hemming process method, which aims to solve the problem of stamping depressions on the appearance surface in the current hemming process.

[0005] To achieve the above object, the present invention proposes a hemming process method, which is applied to the hemming connection of an outer panel and multiple inner panels. The hemming process method comprises the following steps:

[0006] Obtain the angle design range calculated based on the avoidance clearance design value and the overlap amount of the inner and outer plates;

[0007] Adjust the side ends of the inner panels to the corresponding tilt angles according to the angle design range;

[0008] The outer panel is folded over to cover the end of the inner panel and then pressed together by rollers.

[0009] In one embodiment, the step of obtaining the angle design range calculated based on the avoidance clearance design value and the overlap amount of the inner and outer plates specifically includes:

[0010] Calculate the limit design clearance based on the clearance design tolerance;

[0011] The first limit angle value is calculated according to the limit design gap and the overlap amount of the inner and outer plates, and the second limit angle value is calculated according to the radius of the fillet on the surface of the inner plate;

[0012] The first limit angle value and the second limit angle value are respectively taken as breakpoint values to confirm the angle design range.

[0013] In an embodiment, the first limit angle value is A, the limit design gap is a, the overlap amount of the inner and outer plates is b, and sin A > a / b.

[0014] In an embodiment, the second limit angle value is B, and B < 45°.

[0015] In an embodiment, the step of "folding the outer plate and covering the end of the inner plate, and then pressing by the roller" further comprises:

[0016] A preset wrapping thickness is calculated according to the design value of the thickness of the inner plate, the design value of the thickness of the outer plate, and the height gap between the inner and outer plates;

[0017] In the step of "folding the outer plate and covering the end of the inner plate, and then pressing by the roller", the part of the outer plate folded and covering the end of the inner plate is a wrapping part.

[0018] The formation of the wrapping part is determined according to the preset wrapping thickness.

[0019] In an embodiment, the height gap between the inner and outer plates is C, and 0.2 mm ≤ C ≤ 0.5 mm.

[0020] In an embodiment, the step of "determining the formation of the wrapping part according to the preset wrapping thickness" specifically comprises:

[0021] The distance between the edges of the inner and outer plates at the wrapping part is determined according to the preset wrapping thickness.

[0022] The position of the inner plate is adjusted according to the distance between the edges of the inner and outer plates at the wrapping part.

[0023] In an embodiment, the step of "folding the outer plate and covering the end of the inner plate, and then pressing by the roller" further comprises:

[0024] Gluing is performed between the side of the inner plate facing away from the outer plate and the outer plate to form a gluing area on the outer plate.

[0025] In an embodiment, the distance from the edge of the end of the inner plate to the outer plate folding part is L1, and 0.3 mm ≤ L1 ≤ 0.7 mm.

[0026] In one embodiment, the end of the inner plate away from the edge is bent in a direction away from the outer plate;

[0027] The distance between the edge of the glue-coated area away from the end of the inner plate and the bending point of the inner plate is L2, and 0.3mm≤L2≤0.5mm.

[0028] The technical solution of the present invention reduces the occurrence of roller air pressure without changing the design gap between the inner plates by tilting the side ends of multiple inner plates. Specifically, by calculating the angle design range based on the avoidance gap design value and the overlap amount of the inner and outer plates, different angle design ranges can be adaptively obtained according to different design values. By designing the side ends of the inner plate splicing according to the obtained angle design range, it is ensured that there is inner plate support in the vertical direction of the roller travel, thereby solving the problem of stamping depressions on the appearance surface after edge pressing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0030] Figure 1 A schematic diagram of the partial structure of the inner and outer panels during the hemming process according to an embodiment of the present invention;

[0031] Figure 2 for Figure 1 Schematic diagram of the structure from one perspective of the inner and outer panels.

[0032] Description of Figure Numbers:

[0033] 1. Outer panel; 2. Inner panel; 3. Edge wrapping; 4. Glue coating area; 5. Outer panel folding area; 6. Inner panel bending area.

[0034] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] It should be noted that if the embodiments of the present application involve directionality indication (such as up, down, left, right, front, back, etc.), the directionality indication is only used to explain the relative position relationship, motion condition, etc. between the components in a certain posture, and if the certain posture changes, the directionality indication will also change accordingly.

[0037] In addition, if the embodiments of the present application involve the description of "first", "second" and the like, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the scope of protection claimed by the present application.

[0038] The appearance design of the former automobile industry develops rapidly, and the edge covering connection structure design of the automobile sheet metal covering part highly related to the appearance is an important part in the automobile manufacturing process, which is related to the appearance quality and structural strength of the body in white; In the automobile manufacturing industry, the design concept for manufacturing can minimize manufacturing cost, improve product quality and shorten development cycle. Generally, the edge covering connection structure design is to make the outer plate cover the inner plate or the inner plate cover the outer plate through the edge covering connection process, to form the connection of the inner and outer plates and the safe part edge. For the same edge covering, especially in the appearance area, the edge covering connection structure design is to connect the whole continuous outer plate and inner plate, and the complete inner plate edge covering surface is a necessary condition to ensure good edge covering appearance.

[0039] For the special structure of the inner plate, it may not be possible to realize one-piece stamping forming, there may be problems such as excessive local stress, which is easy to cause drawing cracking and other quality defects, and the stamping inner plate needs to be cut into 2 pieces or more sheet metal forms to ensure good stamping formability, and then manufactured into an inner plate assembly through welding and other connection processes. If this part adopts the structure of ordinary continuous edge covering, at the inner plate connection part, because there is an unavoidable inner plate joint gap, under the action of edge covering pressure, obvious appearance quality defects will occur at the corresponding position of the edge covering appearance surface.

[0040] The main purpose of the present application is to provide an edge covering process method, which aims to solve the problem of stamping depression on the appearance surface in the current edge covering process.

[0041] Please refer to Figures 1 to 2To achieve the above-mentioned purpose, the present invention proposes a hemming process method, which is applied to the hemming connection of an outer panel 1 and multiple inner panels 2. The hemming process method includes the following steps:

[0042] S10. Obtaining a design angle range calculated based on the design value of the avoidance gap and the overlap amount of the inner and outer plates.

[0043] It should be noted that the side ends of the multiple inner panels 2 in the pressing direction are arranged in parallel, so as to ensure that the gaps between the inner panels 2 remain consistent, and the design value of the avoidance gap is the vertical distance between the side ends of two adjacent inner panels 2.

[0044] In the specific implementation, the avoidance clearance design value is D, and the tolerance is d. The maximum value of the avoidance clearance is D+d, and the minimum value is Dd. In order to avoid interference between the inner plates 2, it is necessary to ensure that Dd is greater than twice the inner plate 2 cutting edge dimension tolerance. When calculating the angle design range, the avoidance clearance design value is generally set to D+d, so as to ensure that even with the maximum avoidance clearance, the occurrence of roller air pressure can be avoided.

[0045] It is worth mentioning that in order to ensure good hemming quality, the design value of the avoidance gap should be as small as possible.

[0046] S20, adjusting the spliced ​​side ends of the inner panels 2 to corresponding tilt angles according to the designed angle range.

[0047] It should be noted that the tilt angle refers to the acute angle formed by the side end of the inner plate 2 and the direction perpendicular to the direction of travel of the roller, that is, when the angle is 0°, the side end of the inner plate 2 is perpendicular to the direction of travel of the roller, so that a depression will appear at the avoidance gap. Figure 1 In FIG, the tilt angle is marked as α.

[0048] S30, folding the outer panel 1 to cover the end of the inner panel 2, and then pressing them together with rollers.

[0049] The technical solution of the present invention is to reduce the occurrence of roller air pressure without changing the design gap between the inner plates 2 by tilting the side ends of multiple inner plates 2. Specifically, by calculating the angle design range based on the avoidance gap design value and the overlap amount of the inner and outer plates, different angle design ranges can be adaptively obtained according to different design values. By designing the side ends of the spliced ​​inner plates 2 according to the obtained angle design range, it is ensured that there is inner plate 2 support in the vertical direction of the roller travel, thereby solving the problem of stamping depressions on the appearance surface after edge pressing.

[0050] Furthermore, the step of S10, obtaining the angle design range calculated based on the avoidance clearance design value and the overlap amount of the inner and outer plates, specifically includes:

[0051] S11. Calculate the limit design gap based on the gap design tolerance.

[0052] It should be noted that the design value of the avoidance clearance is D, and the tolerance is d. The maximum value of the avoidance clearance is D+d, and the minimum value is Dd. In order to avoid interference between the inner plates 2, it is necessary to ensure that Dd is greater than twice the tolerance of the cutting edge size of the inner plate 2. When calculating the ultimate design clearance, it is necessary to ensure that even under the maximum avoidance clearance, the roller air pressure can be avoided. Generally, the design value of the avoidance clearance is set to D+d.

[0053] S12. Calculate a first limit angle value based on the limit design gap and the overlap amount of the inner and outer plates, and calculate a second limit angle value based on the radius of the fillet on the surface of the inner plate 2.

[0054] It should be noted that in order to eliminate stress concentration in parts, the corners of the inner plate 2 are all provided with rounded corners. Due to the existence of the rounded corners, part of the inner plate 2 will be missing at the corners, resulting in the occurrence of roller air pressure. Especially for excessively large inclination angles, the missing part at the rounded corners will be larger. At the same time, excessive inclination angles will also cause stress concentration.

[0055] It is worth mentioning that the first limit angle value is the minimum value, and the second limit angle value is the maximum value. By calculating the minimum value of the angle range based on the limit design gap and the overlap amount of the inner and outer plates, it is ensured that there is inner plate 2 support in the vertical direction of the roller movement, thereby solving the problem of stamping depressions on the appearance surface after edge pressing. By calculating the minimum value of the angle range based on the radius of the fillet on the surface of the inner plate 2, the situation of roller air pressure caused by partial missing at the corner is prevented, and stress concentration is reduced at the same time.

[0056] It should be further explained that the first limit angle value is A, the limit design gap is a, and the overlap amount of the inner and outer plates is b, satisfying sinA>a / b. With this design, in the direction perpendicular to the direction of travel of the roller, the lower ends of the overlaps between the outer plate 1 and the inner plate 2 can be guaranteed to be supported by the inner plate 2, so that after the rollers are pressed together, no depression will occur, solving the problem of appearance deformation after edging. It is worth mentioning that since the inner plate 2 is provided with rounded corners at the corners, considering the partial loss of the inner plate 2 caused by the rounded corners, the inclination angle can be appropriately increased according to the radius of the rounded corner, and at the same time, it can also prevent local depressions caused by too few supporting parts.

[0057] It should also be noted that when the inclination angle is too large, the missing area at the corner is too large, which will cause extremely uneven force on the edge during pressing, resulting in local depression. To address the above defects, the second limit angle value is B, satisfying B<45°.

[0058] S13. Use the first limit angle value and the second limit angle value as breakpoint values ​​to confirm the angle design range.

[0059] In one embodiment of the present invention, please refer to Figure 2 The step of “S30, folding the outer panel 1 and making it cover the end of the inner panel 2, and then pressing it together with rollers” also includes:

[0060] Calculate the preset edge thickness based on the inner plate thickness design value, outer plate thickness design value and the height gap between the inner and outer plates;

[0061] It is worth mentioning that the height gap between the inner and outer panels refers to the margin left in the height direction between the outer panel 1 and the inner panel 2 during the edge forming process. During the edge forming process, due to the poor plasticity of part of the outer panel 1, the bending part of the outer panel 1 will not be smooth enough, resulting in the final overlap between the outer panel 1 and the inner panel 2 being smaller than the design value. By leaving a height margin in advance, the design length of the outer panel 1 extending from the inner panel 2 is increased, ensuring sufficient overlap length of the inner and outer panels, and preventing interference between the folding parts of the inner panel 2 and the outer panel 1. Figure 2 c represents the preset edge thickness.

[0062] In the step of "S30, folding the outer panel 1 and making it cover the end of the inner panel 2, and then pressing it together with a roller", the part of the outer panel 1 that covers the end of the inner panel 2 after being folded is the edging portion 3; the formation of the edging portion 3 is determined according to the preset edging thickness.

[0063] It should be noted that, in the process of forming the edging portion 3, the gap between the inner panel 2 and the folded portion 5 of the outer panel must also be considered to prevent interference between the inner panel 2 and the outer panel 1. When the edging thickness is determined, the length of the outer panel 1 extending beyond the inner panel 2 must also be increased, so that the folding print of the outer panel 1 is effectively optimized, thereby improving the overall quality and aesthetics of the edging portion 3.

[0064] Specifically, the height gap between the inner and outer plates is C, 0.2 mm ≤ C ≤ 0.5 mm. For example, the height gap C between the inner and outer plates is 0.2 mm, 0.25 mm, 0.3 mm, 0.5 mm, etc. In a specific embodiment, the height gap between the inner and outer plates is 0.2 mm.

[0065] Furthermore, the step of determining the formation of the hemming portion 3 according to the preset hemming thickness specifically includes:

[0066] Determine the distance between the edges of the inner and outer panels at the hemming location based on the preset hemming thickness;

[0067] Adjust the position of the inner panel 2 according to the distance between the edges of the inner and outer panels at the hemming point.

[0068] It is worth mentioning that the distance between the edges of the inner and outer panels is the length of the outer panel 1 extending beyond the inner panel 2 in the direction perpendicular to the movement of the roller before the edging. By determining the distance between the edges of the inner and outer panels at the edging point according to the edging thickness, it can be ensured that the outer panel 1 can be covered on the inner panel 2, thereby ensuring the integrity of the edging.

[0069] In one embodiment of the present invention, please refer to Figure 2 The step of “S30, folding the outer panel 1 and making it cover the end of the inner panel 2, and then pressing it together with rollers” also includes:

[0070] Glue is applied between the outer panel 1 and the inner panel 2 on the side facing away from the flange of the outer panel 1 to form a glue-coated area 4 on the outer panel 1 .

[0071] With such an arrangement, by applying glue on the outer panel 1 , the sealing between the inner panel 2 and the outer panel 1 is effectively improved, thereby improving the stability of the inner panel 2 during the roller pressing process and preventing the inner panel 2 from moving.

[0072] Specifically, to prevent glue overflow toward the outer panel fold 5 during lamination, the position of the glue-coated area 4 is limited. The distance L1 between the edge of the glue-coated area 4 near the end of the inner panel 2 and the outer panel fold 5 is 0.3 mm ≤ L1 ≤ 0.7 mm. For example, the distance L1 between the edge of the glue-coated area 4 near the end of the inner panel 2 and the outer panel fold 5 can be 0.3 mm, 0.35 mm, 0.5 mm, 0.7 mm, etc. In one specific embodiment, the distance between the edge of the glue-coated area 4 near the end of the inner panel 2 and the outer panel fold 5 is 0.5 mm.

[0073] Furthermore, in one embodiment, based on process requirements, the end of the inner panel 2 away from the hemming is bent in a direction away from the outer panel 1. To prevent glue overflow toward the inner panel bend 6 during the lamination process, the position of the glue-coated area 4 is limited. Specifically, the distance L2 from the edge of the glue-coated area 4 away from the end of the inner panel 2 to the inner panel bend 6 is 0.3mm≤L2≤0.5mm. For example, the distance L2 from the edge of the glue-coated area 4 away from the end of the inner panel 2 to the inner panel bend 6 is 0.3mm, 0.35mm, 0.4mm, 0.5mm, etc. In one specific embodiment, the distance from the edge of the glue-coated area 4 away from the end of the inner panel 2 to the inner panel bend 6 is 0.4mm.

[0074] It is worth mentioning that in order to reduce stress concentration, the inner panel bend 6 is also provided with a rounded corner. After the entire edging process is completed, the rounded corner of the inner panel bend 6 will form an interference point with the outer panel 1. By limiting the range of the glue coating area 4, the interference between the rounded corner of the inner panel bend 6 and the outer panel 1 can be reduced.

[0075] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A hemming process method, applied to the hemming connection of an outer panel and multiple inner panels, characterized in that: The hemming process comprises the following steps: Obtaining an angle design range calculated based on the avoidance clearance design value and the overlap amount of the inner and outer panels, specifically including: calculating a limit design clearance based on a clearance design tolerance; calculating a first limit angle value based on the limit design clearance and the overlap amount of the inner and outer panels, and calculating a second limit angle value based on the radius of the fillet on the inner panel surface; and using the first limit angle value and the second limit angle value as breakpoint values ​​to confirm the angle design range; Adjust the side ends of the inner panels to corresponding tilt angles according to the designed angle range; After the outer panel is folded and covered with the end of the inner panel, it is pressed together by rollers; The first limit angle value is A, the limit design gap is a, the overlap amount of the inner and outer plates is b, and sinA>a / b; The second limit angle value is B, where B is less than 45°.

2. The hemming process according to claim 1, wherein: The step of "folding the outer panel and making it cover the end of the inner panel, and then pressing it together with rollers" also includes: Calculate the preset edge thickness based on the inner plate thickness design value, outer plate thickness design value and the height gap between the inner and outer plates; In the step of "folding the outer panel so that it covers the end of the inner panel and then pressing it together with rollers", the portion of the outer panel that covers the end of the inner panel after being folded is the edge portion; The formation of the hemming portion is determined according to a preset hemming thickness.

3. The hemming process according to claim 2, characterized in that: The height gap between the inner and outer plates is C, 0.2mm≤C≤0.5mm.

4. The hemming process according to claim 2, wherein: The step of "determining the formation of the hemming portion according to the preset hemming thickness" specifically includes: Determine the distance between the edges of the inner and outer panels at the hemming location based on the preset hemming thickness; Adjust the position of the inner panel according to the distance between the edges of the inner and outer panels at the hemming point.

5. The hemming process according to claim 1, wherein: The step of "folding the outer panel and making it cover the end of the inner panel, and then pressing it together with rollers" also includes: Glue is applied between the outer plate and the side of the inner plate facing away from the outer plate flange to form a glue-coated area on the outer plate.

6. The hemming process according to claim 5, characterized in that: The distance between the edge of the glue-coated area close to the end of the inner plate and the folded portion of the outer plate is L1, and 0.3 mm ≤ L1 ≤ 0.7 mm.

7. The hemming process according to claim 5, characterized in that: The end of the inner plate away from the edge is bent in a direction away from the outer plate; The distance between the edge of the glue-coated area away from the end of the inner plate and the bending point of the inner plate is L2, and 0.3mm≤L2≤0.5mm.

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