Preparation method of hot stamping door ring

Abstract

The invention discloses a preparation method of a hot stamping door ring. The preparation method comprises the following steps: carrying out a laser uncoiling blanking process on a steel plate for thermal forming to obtain a top material sheet, a B column material sheet, an A column material sheet, an H column material sheet and a threshold material sheet; tailored blank laser welding is conducted on the top material piece and the column B material piece together to form a first tailored blank laser welding material piece, and tailored blank laser welding is conducted on the column A material piece and the column H material piece together to form a second tailored blank laser welding material piece; the two laser tailor-welded material pieces are subjected to laser tailor-welded together to form an open door ring material piece; the open door ring material piece and the doorsill material piece are connected together through a spot welding technology to form a closed door ring material piece; carrying out hot stamping on the closed door ring material sheet to obtain a door ring hot stamping part; performing laser cutting on the door ring hot stamping part to obtain a door ring laser part; and welding spot repairing is carried out on the doorsill of the door ring laser piece to form the hot stamping door ring. By adopting the preparation method, the tailored blank laser welding difficulty can be reduced, the tailored blank laser welding cost can be saved, and the rigidity of the hot stamping process part can be improved.

Description

Technical Field

[0001] The invention relates to the field of hot-formed integral door rings, and in particular to a preparation method of hot-stamped door rings. Background Art

[0002] Hot stamping door ring is an important component to improve vehicle safety, reduce vehicle weight, reduce vehicle energy consumption, and reduce vehicle carbon emissions. The door ring integrates multiple parts such as A-pillar, B-pillar, door sill, top side beam, etc.

[0003] At present, in the production process of hot stamping door rings, most of them are first laser welded into annular sheets, and then hot stamped. However, the annular door rings that are all connected by laser welding require high tooling positioning accuracy because they need to eliminate the cumulative error of the welds. The cost of positioning tooling for laser welding is very high. There are also open door ring sheets similar to f that are directly used. Although the difficulty of welding is reduced, the H-pillar and B-pillar of the open door ring are heavier, and there is only a thin A-pillar connection. The overall rigidity of the hot-formed parts is low and it is easy to deform during transportation. There are also door ring sheets that are only connected by spot welding, but the overall strength after hot forming is poor. There are also door rings that use spot welding and laser welding at the same time, but the main board that is laser welded first is a closed door ring sheet, and the patch plate is spot welded later. The difficulty of laser welding the main board has not been reduced. Summary of the invention

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preparing a hot stamping door ring comprises the following steps:

[0006] S1, performing a laser uncoiling and blanking process on the hot forming steel sheet to obtain a top sheet, a B-pillar sheet, an A-pillar sheet, an H-pillar sheet and a door sill sheet;

[0007] S2, laser welding the top sheet and the B-pillar sheet together to form a first laser welded sheet, and laser welding the A-pillar sheet and the H-pillar sheet together to form a second laser welded sheet;

[0008] S3, laser welding the first laser welded sheet and the second laser welded sheet together to form an open door ring sheet;

[0009] S4, using a spot welding process to connect the open door ring material piece and the threshold material piece together to form a closed door ring material piece;

[0010] S5, hot stamping the closed door ring sheet using a hot stamping die to obtain a hot stamped door ring part;

[0011] S6, laser cutting the door knocker hot stamping part to obtain a door knocker laser part;

[0012] S7, performing additional welding points on the threshold of the door ring laser component to form the hot stamping door ring.

[0013] In some of the embodiments, the step S1 specifically comprises: performing laser uncoiling and blanking processes on five hot-forming steel plates having different material thicknesses or strengths to obtain the top sheet, B-pillar sheet, A-pillar sheet, H-pillar sheet and door sill sheet.

[0014] In some of the embodiments, in step S2 and step S3, the laser-welded welds are both made using a universal laser welding line.

[0015] In some of the embodiments, in step S2 , a straight extension line of the weld between the top sheet and the B-pillar sheet does not intersect with an outer edge of the top sheet.

[0016] In some of the embodiments, in step S3 , a straight extension line of the weld between the top sheet and the A-pillar sheet does not intersect with an outer edge of the B-pillar sheet.

[0017] In some of the embodiments, in step S4, a stamping formability simulation analysis is first performed using CAE analysis software to determine the position information of the welding points of the open door ring sheet and the threshold sheet, and to ensure that the thinning rate at each welding point is less than or equal to 17%, and then a spot welding process is used to connect the open door ring sheet and the threshold sheet together to form a closed door ring sheet according to the position information of the welding points.

[0018] In some of the embodiments, in the S4 step, the opening door ring sheet and the door sill sheet are first positioned using a spot welding tool, and the two ends of the door sill sheet overlap with the two ends of the opening door ring sheet respectively, and after positioning, the two ends of the door sill sheet are spot welded to the B-pillar sheet and the H-pillar sheet of the opening door ring sheet respectively.

[0019] In some of the embodiments, in step S4, the overlapping lengths of both ends of the threshold material piece and the opening door ring material piece are 10-50 mm, and there are 1-4 welding points at the overlapping ends of the sub-material piece, and the spacing between the outer edges of adjacent welding points is less than 10 mm.

[0020] In some embodiments, the hot stamping die comprises a lower die insert, a pressure core and an upper die insert, wherein the pressure core is disposed on one side of the upper die insert and is movable relative to the upper die insert, and the upper die insert is disposed on the lower die insert;

[0021] In step S5, while hot stamping the closed door ring sheet using a hot stamping die, the closed door ring sheet is placed on the lower die insert, and after the two ends of the threshold sheet and the overlapping area of ​​the open door ring sheet are pressed by the pressing core, the closed door ring sheet is continued to be pressed down by the upper die insert to press out the door ring hot stamping part.

[0022] In some of the embodiments, in step S4, after the open door ring sheet and the threshold sheet are connected together to form a closed door ring sheet by using a spot welding process, a process of welding a patch plate on the closed door ring sheet by using a spot welding process is also included.

[0023] Compared with the prior art, the present invention has at least one of the following advantages or beneficial effects:

[0024] The present invention provides a preparation method of a hot stamping door ring, which can reduce the difficulty of laser welding and save the cost of laser welding, and can also improve the rigidity of parts in the hot stamping process, prevent deformation during transportation, ensure the overall strength of the door ring, and thus expand the application of hot stamping doors in automobiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention and its features, appearance and advantages will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings. The same reference numerals indicate the same parts in all the drawings. The drawings are not drawn to scale, and emphasis is placed on illustrating the subject matter of the present invention.

[0026] Figure 1 Flow chart of a method for preparing a hot stamping door ring according to an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the structure of the opening door ring sheet in the embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the structure of the closed door ring material sheet in an embodiment of the present invention;

[0029] Figure 4 It is a partial schematic diagram of the spot welding position on the closed door ring material sheet with two welding points in the embodiment of the present invention;

[0030] Figure 5 It is a partial schematic diagram of the first welding point and the supplementary welding point in the embodiment of the present invention;

[0031] Figure 6 It is a partial schematic diagram of a hot stamping die in an embodiment of the present invention;

[0032] Figure 7 Schematic diagram of a closed door ring sheet welded with a patch plate in an embodiment of the present invention;

[0033] Figure 8 It is a partial schematic diagram of a closed door ring sheet with three welding points in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0035] Embodiment 1:

[0036] like Figure 1 As shown, this embodiment provides a method for preparing a hot stamping door ring combining laser welding and spot welding. Specifically, the preparation method includes the following steps:

[0037] S1, five pieces of hot-forming steel plates with different material thickness or strength are subjected to laser unwinding and blanking process to obtain five blanking pieces a~e of the door ring, and the five blanking pieces a~e are respectively the top piece a, the B-pillar piece b, the A-pillar piece c, the H-pillar piece d and the door sill piece e.

[0038] In step S1, since there is no need to use a customized blanking die for blanking, laser uncoiling and blanking are used, thus saving mold costs.

[0039] S2, first use a universal laser welding line to weld the top sheet a and the B-pillar sheet b into an integral sheet, i.e., the first laser-welded sheet; use a universal laser welding line to weld the A-pillar sheet c and the H-pillar sheet d into an integral sheet, i.e., the second laser-welded sheet; and the straight extension line of the weld between the top sheet a and the B-pillar sheet b does not intersect with the outer edge of the top sheet a, otherwise the universal laser welding line will damage the outer edge of the sheet a.

[0040] S3, such as Figure 2 As shown, the first laser-welded sheet formed by welding the top sheet a and the B-pillar sheet b, and the second laser-welded sheet formed by welding the A-pillar sheet c and the H-pillar sheet d are welded together to form an opening door ring sheet using a universal laser welding line. The straight extension line of the weld between the top sheet a and the A-pillar sheet c does not intersect with the outer edge of the sheet b, otherwise the universal laser welding line will intersect the outer edge of the B-pillar sheet b.

[0041] In the above steps S2 and S3, the welds between the top sheet a and the B-pillar sheet b, the welds between the A-pillar sheet c and the H-pillar sheet d, and the welds between the top sheet a and the A-pillar sheet c are all laser welded using universal laser welding lines instead of customized laser welding positioning tooling and dedicated door ring welding lines, thereby eliminating the need for customized laser welding tooling and reducing the welding cost.

[0042] S4, such as Figure 3 and 4 As shown, the open door ring sheet and the threshold sheet are connected together by a spot welding process to form a closed door ring sheet. Specifically, the open door ring sheet and the threshold sheet e are first positioned using a spot welding fixture, and the two ends of the threshold sheet e are overlapped with the two ends of the open door ring sheet, and after positioning and clamping, the two ends of the threshold sheet e are spot welded to the B-pillar sheet b and the H-pillar sheet d of the open door ring sheet, and the open door ring sheet and the threshold sheet e are connected to form a closed door ring sheet by a spot welding process, and the two ends of the threshold sheet e are connected to the sheet b and the sheet d respectively, and the threshold sheet e does not completely overlap with the open door ring sheet, only the ends overlap, and the welding point is close to the two ends of the threshold sheet e, the edges of the B-pillar sheet b, and the H-pillar sheet d. The overlapping lengths of the two ends of the threshold material piece e and the opening door ring material piece are 10~50mm respectively, and there are two welding points at the overlapping parts of the two ends of the threshold material piece e, namely, welding point 1 is first made, and the spacing between the outer edges of adjacent first welding points 1 is less than 10mm.

[0043] In the above step S4, CAE analysis software is first used to perform stamping formability simulation analysis to determine the position information of the welding points of the open door ring sheet and the threshold sheet e, and to ensure that the thinning rate at each welding point in the analysis result is less than or equal to 17%, and then the open door ring sheet and the threshold sheet e are connected together to form a closed door ring sheet using a spot welding process according to the position information of the welding points.

[0044] S5, such as Figure 5 As shown, a hot stamping die is used to hot stamp the closed door ring sheet to obtain a door ring hot stamping part. Specifically, the hot stamping die comprises a lower die insert 3, a pressure core 4 and an upper die insert 5, the pressure core 4 is arranged on one side of the upper die insert 5 and is movable relative to the upper die insert 5, and the upper die insert 5 is arranged on the lower die insert 3; specifically, in the process of hot stamping the closed door ring sheet by using the hot stamping die, the closed door ring sheet is placed on the lower die insert 3, and after the pressure core 4 is used to press the overlapping area of ​​the two ends of the threshold sheet e and the open door ring sheet, the upper die insert 5 is continued to press down the closed door ring sheet to press out the door ring hot stamping part.

[0045] S6, laser cutting the door ring hot stamping part to obtain a door ring laser part.

[0046] It should be noted here that in the process of laser cutting the door ring hot stamping part, the boundary of the threshold sheet e is not fully cut (specifically, the area where the two ends of the threshold sheet e overlap with the opening door ring sheet does not need to be laser cut), and the boundary contour tolerance is greater than 4 mm.

[0047] S7, such as Figure 6 In the process, the threshold of the door ring laser part is supplemented with welding points to strengthen the strength of the hot stamping door ring, and 3 welding points are supplemented (i.e. welding point 2 is supplemented). There are three main reasons for supplementing the welding points: ① If the welding points here are not supplemented, the rigidity will be weaker than that of the closed door ring, which will affect the automated assembly of the whole vehicle. ② If the welding points here are made before hot stamping, they will be torn during the forming process. ③ The main work of this process is to weld other auxiliary parts to the hot stamping door ring, and supplementing the welding points is only incidental. If this process is added only for supplementing the welding points, the cost of the door ring preparation method of the present invention will be increased.

[0048] Embodiment 2:

[0049] like Figure 7 and 8 As shown, this embodiment provides a method for preparing a hot stamping door ring by combining laser welding and spot welding, and the method is substantially the same as that of the first embodiment, except that:

[0050] like Figure 7 As shown, in step S4, in addition to connecting the open door ring sheet and the door sill sheet into a closed door ring sheet using a spot welding process, when the spot welding tool is positioned, the first patch plate 6 and the second patch plate 7 will also be spot welded to the A-pillar sheet c and the B-pillar sheet b of the closed door ring sheet respectively by a spot welding process, thereby further increasing the strength of the vehicle body.

[0051] like Figure 8 As shown, in step S4, when the open door ring sheet and the threshold sheet e are connected to form a closed door ring sheet using a spot welding process, the number of welding points at both ends of the threshold sheet e is 3 (i.e., welding point 8 is first made in the figure), thereby further enhancing the strength of the parts during the hot stamping process, reducing deformation during transportation, and reducing the risk of welding point failure.

[0052] In summary, the preparation method of the hot stamping door knocker provided by the present invention has a lower difficulty in welding the blanks than the closed door knocker formed entirely by laser welding. It is not necessary to use a customized blanking die for blanking, but laser unwinding and blanking are used to save mold costs. It is not necessary to use customized laser welding tooling, but a universal laser welding line is used, which reduces the welding cost. Compared with the open door knocker that is not closed at the threshold, the hot stamping process has good strength and is not easily deformed during transportation. Compared with the door knocker connected by full spot welding, the overall strength of the door knocker is better.

[0053] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing a hot stamping door knocker, characterized in that: The steps include: S1, performing a laser uncoiling and blanking process on the hot forming steel sheet to obtain a top sheet, a B-pillar sheet, an A-pillar sheet, an H-pillar sheet and a door sill sheet; S2, laser welding the top sheet and the B-pillar sheet together to form a first laser welded sheet, and laser welding the A-pillar sheet and the H-pillar sheet together to form a second laser welded sheet; S3, laser welding the first laser welded sheet and the second laser welded sheet together to form an open door ring sheet; S4, using a spot welding process to connect the open door ring material piece and the threshold material piece together to form a closed door ring material piece; S5, hot stamping the closed door ring sheet using a hot stamping die to obtain a hot stamped door ring part; S6, laser cutting the door knocker hot stamping part to obtain a door knocker laser part; S7, performing additional welding points on the threshold of the door ring laser component to form the hot stamping door ring.

2. The method for preparing a hot stamping door ring according to claim 1, characterized in that: The step S1 specifically includes: performing laser unwinding and blanking processes on five hot-forming steel plates with different material thicknesses or strengths to obtain the top sheet, B-pillar sheet, A-pillar sheet, H-pillar sheet and door sill sheet.

3. The method for preparing a hot stamping door ring according to claim 1, characterized in that: In step S2 and step S3, the laser welding seams are formed using a universal laser welding line.

4. The method for preparing a hot stamping door ring according to claim 1, characterized in that: In step S2 , a straight extension line of the weld between the roof panel and the B-pillar panel does not intersect with an outer edge of the roof panel.

5. The method for preparing a hot stamping door ring according to claim 1, characterized in that: In step S3 , the straight extension line of the weld between the top sheet and the A-pillar sheet does not intersect the outer edge of the B-pillar sheet.

6. The method for preparing a hot stamping door ring according to claim 1, characterized in that: In step S4, CAE analysis software is first used to perform stamping formability simulation analysis to determine the position information of the welding points of the open door ring sheet and the threshold sheet, and to ensure that the thinning rate at each welding point is less than or equal to 17%, and then the open door ring sheet and the threshold sheet are connected together to form a closed door ring sheet using a spot welding process according to the position information of the welding points.

7. The method for preparing a hot stamping door ring according to claim 1, characterized in that: In the S4 step, the opening door ring sheet and the door sill sheet are first positioned using a spot welding tool, and the two ends of the door sill sheet overlap with the two ends of the opening door ring sheet respectively, and after positioning, the two ends of the door sill sheet are spot welded to the B-pillar sheet and the H-pillar sheet of the opening door ring sheet respectively.

8. The method for preparing a hot stamping door ring according to claim 7, characterized in that: In step S4, the overlapping lengths of both ends of the threshold material piece and the opening door ring material piece are 10-50 mm, and there are 1-4 welding points at the overlapping ends of the sub-material piece, and the spacing between the outer edges of adjacent welding points is less than 10 mm.

9. The method for preparing a hot stamping door ring according to claim 7, characterized in that: The hot stamping die comprises a lower die insert, a pressure core and an upper die insert, wherein the pressure core is arranged on one side of the upper die insert and is movable relative to the upper die insert, and the upper die insert is arranged on the lower die insert; In step S5, while hot stamping the closed door ring sheet using a hot stamping die, the closed door ring sheet is placed on the lower die insert, and after the two ends of the threshold sheet and the overlapping area of ​​the open door ring sheet are pressed by the pressing core, the closed door ring sheet is continued to be pressed down by the upper die insert to press out the door ring hot stamping part.

10. The method for preparing a hot stamping door ring according to claim 1, characterized in that: In step S4, after the open door ring material piece and the threshold material piece are connected together to form a closed door ring material piece by using a spot welding process, a process of welding a patch plate on the closed door ring material piece by using a spot welding process is also included.

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