Composite connection method for die-casting structural part and hot-formed steel part

Abstract

The invention discloses a composite connection method for a die-casting structural part and a hot-formed steel part, and belongs to the technical field of automobile part production methods. The composite connection method for the die-casting structural part and the hot-formed steel part comprises the steps that according to product requirements, the die-casting structural part is manufactured through a vacuum die-casting process, the hot-formed steel part is manufactured through a hot forming stamping process, and a transition connecting part is manufactured through a cold stamping process; the transition connecting piece and the die-casting structural piece are clamped, the transition connecting piece is attached to the upper surface of the die-casting structural piece, the thermal forming steel piece is clamped, and the thermal forming steel piece is attached to the upper surface of the transition connecting piece; self-piercing riveting is conducted on the die-casting structural part and the transition connecting part according to the self-piercing riveting quality requirement; according to the spot welding quality requirement, spot welding is conducted on the hot-formed steel part and the transition connecting part, the die-casting structural part, the transition connecting part and the hot-formed steel part are connected into a combination, and the connection precision and the connection quality between the die-casting structural part and the hot-formed steel part can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile accessory production methods, and in particular relates to a method for composite connection of a die-cast structural member and a hot-formed steel member. BACKGROUND

[0002] The development of a passenger vehicle body is heading towards the direction of simultaneously considering light weight and high safety. Light weight drives the development of the vehicle body to adopt more and more light weight materials and more advanced light weight structures, such as the super-large size one-piece die-cast aluminum alloy rear floor and front engine compartment structural members that are being widely promoted and applied in the industry, and the body one-piece die-cast magnesium alloy structural member that is being developed. High safety requires the body framework to form a more secure cage type protective structure, and to match the advanced 1500MPa, 1800MPa and 2000MPa grade hot-formed steel members in the industry.

[0003] With the gradual increase of the application proportion of the body die-cast structural member and the hot-formed steel member, it will inevitably involve the connection between the die-cast light alloy structural member and the hot-formed steel member. Therefore, in order to achieve the design and development goal of final light weight and ultra-high safety, the problem of high quality and high stability connection between the large size die-cast light alloy structural member and the hot-formed steel member must be solved.

[0004] In the related art, the traditional riveting or welding method is difficult to be applied to the connection of the die-cast light alloy structural member and the hot-formed high strength steel, resulting in that the connection precision and connection quality of the die-cast light alloy structural member and the hot-formed high strength steel are often poor. SUMMARY

[0005] The present application aims to at least solve one of the problems in the prior art. To this end, the present application provides a method for composite connection of a die-cast structural member and a hot-formed steel member, which is beneficial to improve the connection precision and connection quality between the die-cast structural member and the hot-formed steel member.

[0006] The method for composite connection of the die-cast structural member and the hot-formed steel member according to the embodiments of the present application comprises: manufacturing the die-cast structural member by using a vacuum die-casting process, manufacturing the hot-formed steel member by using a hot-forming stamping process, and manufacturing the transition connecting member by using a cold stamping process according to product requirements; clamping the transition connecting member and the die-cast structural member, and attaching the transition connecting member to the upper surface of the die-cast structural member, clamping the hot-formed steel member, and attaching the hot-formed steel member to the upper surface of the transition connecting member; self-punch riveting the die-cast structural member and the transition connecting member according to self-punch riveting quality requirements, so that the attachment area of the transition connecting member and the die-cast structural member is realized multi-point riveting; The hot-formed steel part and the transition connecting piece are spot-welded according to the spot-welding quality requirement, so that the abutting area of the hot-formed steel part and the transition connecting piece is multi-point welded.

[0007] The composite connecting method of the die-casting structural part and the hot-formed steel part has at least the following beneficial effects: the composite connecting method of the die-casting structural part and the hot-formed steel part can manufacture the transition connecting piece through the cold stamping process, so that the tensile strength of the transition connecting piece is less than the tensile strength of the hot-formed steel part; the composite connecting method of the die-casting structural part and the hot-formed steel part can clamp the transition connecting piece and the die-casting structural part, and abut the transition connecting piece on the upper surface of the die-casting structural part, so as to fix the relative position relationship between the transition connecting piece and the die-casting structural part; the composite connecting method of the die-casting structural part and the hot-formed steel part can clamp the hot-formed steel part, and abut the hot-formed steel part on the upper surface of the transition connecting piece, that is, the transition connecting piece is clamped between the die-casting structural part and the hot-formed steel part, so as to fix the position relationship of the three and reserve the gun space for riveting and welding; the composite connecting method of the die-casting structural part and the hot-formed steel part can self-punch rivet the die-casting structural part and the transition connecting piece according to the self-punch riveting quality requirement, so that the abutting area of the die-casting structural part and the transition connecting piece is multi-point self-punch riveted; the composite connecting method of the die-casting structural part and the hot-formed steel part can spot-weld the hot-formed steel part and the transition connecting piece according to the spot-welding quality requirement, so that the abutting area of the hot-formed steel part and the transition connecting piece is multi-point welded; that is, the indirect connection of the die-casting structural part and the hot-formed steel part is realized through the transition connecting piece as a carrier, so as to effectively solve the problem that the die-casting structural part cannot obtain high stability and high reliability connection points when the die-casting structural part is connected with the hot-formed steel part through self-punch riveting due to the low local material ductility and large fluctuation; the organic combination of the self-punch riveting and the resistance spot welding reduces the manufacturing cost and improves the connection precision, sealing and corrosion prevention effect; the composite connecting method of the die-casting structural part and the hot-formed steel part is produced by using the existing production line without additional equipment, so as to reduce the investment and manufacturing cost.

[0008] According to some embodiments of the present application, clamping the transition connecting piece and the die-casting structural part, and abutting the transition connecting piece on the upper surface of the die-casting structural part comprises: The die-casting structural part is formed with a connecting groove matched with the transition connecting piece, the transition connecting piece is covered above the connecting groove, and the transition connecting piece and the die-casting structural part are overlapped along the edge of the connecting groove, and the overlapping size of the transition connecting piece and the die-casting structural part is controlled to be 20mm to 25mm.

[0009] According to some embodiments of the present application, clamping the hot-formed steel part, and abutting the hot-formed steel part on the upper surface of the transition connecting piece comprises: The edge of the hot-formed steel part and the transition connecting piece is overlapped, and the overlapping size of the hot-formed steel part and the transition connecting piece is controlled to be 16mm to 23mm.

[0010] According to some embodiments of the present application, the self-piercing riveting of the die-cast structural member and the transition connecting member is performed according to self-piercing riveting quality requirements, comprising: The lap joint of the die-cast structural member and the transition connecting member is subjected to multi-point self-piercing riveting, so that the lap joint of the die-cast structural member and the transition connecting member is formed with a plurality of self-piercing riveting points, and adjacent two self-piercing riveting points are spaced apart by 35mm to 50mm.

[0011] According to some embodiments of the present application, the self-piercing riveting of the die-cast structural member and the transition connecting member is performed according to self-piercing riveting quality requirements, comprising: The interlocking value of the self-piercing riveting point is controlled to be greater than or equal to 0.25mm, the undercut thickness is controlled to be greater than or equal to 0.1mm, and the head protrusion height is controlled to be -0.5mm to 0.3mm.

[0012] According to some embodiments of the present application, the spot welding of the hot-formed steel member and the transition connecting member is performed according to spot welding quality requirements, comprising: The lap joint of the transition connecting member and the hot-formed steel member is subjected to multi-point resistance spot welding, so that the lap joint of the transition connecting member and the hot-formed steel member is formed with a plurality of resistance welding points, and adjacent two resistance welding points are spaced apart by 40mm to 60mm.

[0013] According to some embodiments of the present application, the spot welding of the hot-formed steel member and the transition connecting member is performed according to spot welding quality requirements, comprising: The nugget diameter of the resistance welding point is controlled to be greater than or equal to 3.5 mm, the minimum penetration is controlled to be greater than or equal to 0.2mm, and t is the thickness of the thinner sheet among the transition connecting member and the hot-formed steel member.

[0014] According to some embodiments of the present application, a hot-formed steel member is manufactured by a hot-forming stamping process, and a transition connecting member is manufactured by a cold stamping process, comprising: The hot-formed steel member is manufactured by the hot-forming stamping process, and the tensile strength of the hot-formed steel member is controlled to be 1100MPa to 2100MPa; The transition connecting member is manufactured by the cold stamping process, and the tensile strength of the transition connecting member is controlled to be 500MPa to 1000MPa, and the thickness of the transition connecting member is controlled to be 1.2mm to 2.4mm.

[0015] According to some embodiments of the present application, before the self-piercing riveting of the die-cast structural member and the transition connecting member is performed according to self-piercing riveting quality requirements, the method further comprises the following steps: Self-piercing riveting process parameters satisfying the self-piercing riveting quality requirements are obtained through process tests, and the self-piercing riveting process parameters include rivet model, rivet shape, rivet die shape, riveting force and riveting speed; The point welding process parameters meeting the point welding quality requirements are obtained through process tests, and the point welding process parameters include welding current, current waveform, welding time, holding time, pre-pressing time, electrode pressure, electrode diameter and electrode shape.

[0016] According to some embodiments of the present application, the method for composite connection of die-cast structural member and hot-formed steel member further comprises: selecting multiple self-piercing riveting points and multiple resistance welding points distributed dispersedly or uniformly on the assembly; detecting the self-piercing riveting points according to the self-piercing riveting quality requirements, and detecting the resistance welding points according to the point welding quality requirements; when the multiple self-piercing riveting points and the multiple resistance welding points are all qualified, determining the corresponding connection technical parameters.

[0017] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0018] The present application will be further described below in conjunction with the drawings and embodiments, wherein: Figure 1 the structure schematic diagram of the die-cast structural member, the transition connecting member and the hot-formed steel member connected in sequence for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 2 the structure schematic diagram of the die-cast structural member, the transition connecting member and the hot-formed steel member separated from each other for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 3 the structure schematic diagram of the self-piercing riveting point for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 4 the structure schematic diagram of the resistance welding point for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 5 the flow chart of the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 6 the flow chart of manufacturing the transition connecting member and the hot-formed steel member for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 7 the flow chart of clamping the die-cast structural member, the transition connecting member and the hot-formed steel member for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 8 the flow chart of self-piercing riveting the die-cast structural member and the transition connecting member for the method for composite connection of die-cast structural member and hot-formed steel member according to an embodiment of the present application; Figure 9 The flow chart of resistance spot welding of the transition connecting piece and the hot-formed steel piece in the method for composite connecting of the die-cast structural piece and the hot-formed steel piece according to an embodiment of the present application; Figure 10 The flow chart of obtaining the self-punching riveting process parameters and the spot welding process parameters through process test in the method for composite connecting of the die-cast structural piece and the hot-formed steel piece according to an embodiment of the present application; Figure 11 The flow chart of quality detection in the method for composite connecting of the die-cast structural piece and the hot-formed steel piece according to an embodiment of the present application.

[0019] Reference signs: 100, die-cast structural piece; 110, connecting groove; 200, transition connecting piece; 300, hot-formed steel piece; 400, self-punching riveting joint; 500, resistance welding spot; 600, rivet. DETAILED DESCRIPTION

[0020] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0021] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0022] In the description of the present application, multiple refers to two or more. If there is a description of first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0023] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0024] At present, the application of large-scale die-cast light alloy structural parts plays a significant role in promoting the lightweight level and the improvement of rigidity and strength of the vehicle body, and the efficiency and cost reduction of the manufacturing process. With the gradual increase of the application proportion of die-cast structural parts 100 and hot-formed steel parts 300, it is inevitable to involve the connection between the die-cast structural parts 100 and the hot-formed steel parts 300.

[0025] In the industry, the connection between the die-cast light alloy structural parts and the 1100MPa or below vehicle body steel plate stamping parts is mainly based on self-piercing riveting technology. However, for higher strength steel plates, especially high-strength steel materials with a strength higher than 1100MPa, self-piercing riveting technology cannot achieve continuous multi-point high-quality and high-stability connection. For the connection between the hot-formed steel parts 300 and the die-cast light alloy parts (i.e. die-cast structural parts 100), self-piercing riveting technology even faces the problem of being unable to connect. In addition, for large-scale die-cast structural parts 100, since the self-piercing riveting gun has relatively high requirements for its own rigidity, and its jaw only has one type of C-shaped structure, the riveting flexibility of the connection points of the large-scale die-cast structural parts 100 far away from the connection edge or located at the center of the casting part is much lower than that of the traditional resistance spot welding. Even under the premise that the material riveting is feasible, the riveting process implementation is also relatively difficult.

[0026] In view of the above two difficulties, the commonly used solution in the industry is to replace self-piercing riveting with pull-riveting connection. However, pull-riveting connection requires pre-machining of pre-made holes on the die-cast structural parts 100 and the hot-formed steel parts 300, and then achieves connection through bolt fastening. Although this method can achieve connection, the connection precision, sealing and corrosion prevention effect are greatly compromised, and it is not easy to realize automation. In addition, in order to obtain better corrosion prevention effect, the pull-riveting nut is generally selected to have a blind end structure, and a corresponding specification bolt needs to be matched, which will greatly increase the cost of a single connection point.

[0027] Referring to Figures 1 to 11 The die-cast structural part and hot-formed steel part composite connection method of one embodiment of the present application can be applied to the connection between the die-cast light alloy structural part (die-cast structural part 100) and the hot-formed high-strength steel (hot-formed steel part 300), and can improve the connection precision and connection quality of the die-cast light alloy structural part and the hot-formed high-strength steel. The die-cast structural part and hot-formed steel part composite connection method comprises the following steps: Step S100, manufacturing the die-cast structural part 100 by vacuum die-casting process, manufacturing the hot-formed steel part 300 by hot-forming stamping process, and manufacturing the transition connecting part 200 by cold stamping process according to product requirements; Step S200, clamping the transition connecting part 200 and the die-cast structural part 100, and attaching the transition connecting part 200 to the upper surface of the die-cast structural part 100, clamping the hot-formed steel part 300, and attaching the hot-formed steel part 300 to the upper surface of the transition connecting part 200; Step S300, according to the self-piercing riveting quality requirements, the die casting structure 100 and the transition connector 200 are self-piercing riveted, so that the transition connector 200 and the die casting structure 100 are multi-point riveted in the bonding area; Step S400, according to the spot welding quality requirements, the hot-formed steel part 300 and the transition connector 200 are spot welded, so that the hot-formed steel part 300 and the transition connector 200 are multi-point welded in the bonding area, and the die casting structure 100, the transition connector 200 and the hot-formed steel part 300 are connected into a combination.

[0028] Referring to Figure 1 , Figure 2 and Figure 5 , in step S100, the die casting structure and hot-formed steel part composite connection method can be used to manufacture the die casting structure 100, the hot-formed steel part 300 and the transition connector 200 according to product requirements. Specifically, the die casting structure and hot-formed steel part composite connection method uses vacuum die casting process to manufacture the die casting structure 100, which can be used as an aluminum alloy rear floor, front engine compartment and other structural parts of the automobile. The die casting structure and hot-formed steel part composite connection method can use hot forming stamping process to manufacture the hot-formed steel part 300, which can be used as a vehicle body frame.

[0029] Referring to Figure 1 , Figure 2 and Figure 5 , the die casting structure and hot-formed steel part composite connection method can manufacture the transition connector 200 through cold stamping process, so that the tensile strength of the transition connector 200 is less than that of the hot-formed steel part 300, so as to realize the connection between the transition connector 200 and the die casting structure 100 and the hot-formed steel part 300.

[0030] Referring to Figure 1 , Figure 2 and Figure 5 , in step S200, the die casting structure and hot-formed steel part composite connection method can realize the fixation of the die casting structure 100, the transition connector 200 and the hot-formed steel part 300 through the clamp, and realize the assembly of the die casting structure 100, the transition connector 200 and the hot-formed steel part 300. The die casting structure 100 is located at the bottom layer, the transition connector 200 is connected to the upper surface of the die casting structure 100, and the hot-formed steel part 300 is connected to the upper surface of the transition connector 200, i.e. the hot-formed steel part 300 is located at the top layer, and the transition connector 200 is clamped between the die casting structure 100 and the hot-formed steel part 300, so that the transition connector 200 has good shape bonding with the die casting structure 100 and the hot-formed steel part 300, thereby fixing the positional relationship of the three and reserving the gun space for riveting and welding.

[0031] Referring to Figure 1 , Figure 2 and Figure 5 , in steps S300 and S400, the composite connection method of the die-cast structural member and the hot-formed steel member can perform self-punching riveting on the die-cast structural member 100 and the transition connecting member 200 according to the self-punching riveting quality requirements, so that the transition connecting member 200 and the die-cast structural member 100 realize multi-point self-punching riveting in the bonding area, and the hot-formed steel member 300 and the transition connecting member 200 are spot welded according to the spot welding quality requirements, so that the hot-formed steel member 300 and the transition connecting member 200 realize multi-point welding in the bonding area.

[0032] Referring to Figure 1 , Figure 2 and Figure 5 , that is, the composite connection method of the die-cast structural member and the hot-formed steel member uses the transition connecting member 200 as a carrier, thereby realizing indirect connection of the die-cast structural member 100 and the hot-formed steel member 300, and combining the advantages of self-punching riveting and resistance spot welding, at least the following beneficial effects are achieved: (1) By arranging the transition connecting member 200 made of advanced high-strength steel between the large vehicle body die-cast structural member 100 and the hot-formed steel member 300, the technical problem that the die-cast structural member 100 cannot obtain high-stable and high-reliable connection points when using self-punching riveting connection between the die-cast structural member 100 and the hot-formed steel member 300 due to low material elongation and large fluctuation of the die-cast structural member 100 is effectively solved.

[0033] (2) The transition connecting member 200 made of advanced high-strength steel is first connected to the vehicle body die-cast structural member 100 through self-punching riveting, replacing the existing pull rivet nut connection, thereby reducing the manufacturing cost and improving the connection precision, sealing and corrosion prevention effect; at the same time, since the size of the transition connecting member 200 is smaller than the size of the die-cast structural member 100 and the hot-formed steel member 300, self-punching riveting is easy to implement and eliminates the problem of poor flexibility of the rivet gun caused by the distance of the self-punching riveting point 400 from the edge of the large die-cast structural member 100.

[0034] (3) The transition connecting member 200 made of advanced high-strength steel is first riveted to the vehicle body die-cast structural member 100, and then the transition connecting member 200 made of advanced high-strength steel is spot welded to the hot-formed steel member 300, which can realize fusion with the existing production line, without the need for additional new connection equipment, thereby reducing investment and manufacturing cost.

[0035] (4) Since the transition connecting member 200 made of advanced high-strength steel is used, the development size of the die-cast structural member 100 can be reduced to a certain extent, the structure of the die-cast structural member 100 is simplified, and then the difficulty of ensuring the material performance of the die-cast structural member 100 at the forming and connecting edge area is reduced, and the development quality is improved.

[0036] Referring to Figure 1 ,Figure 2 and Figure 6 As shown in Step S110, the hot forming stamping process is used to manufacture the hot forming steel piece 300, and the tensile strength of the hot forming steel piece 300 is controlled to be 1100MPa to 2100MPa. Step S120, the cold stamping process is used to manufacture the transition connecting piece 200, and the tensile strength of the transition connecting piece 200 is controlled to be 500MPa to 1000MPa, and the thickness is controlled to be 1.2mm to 2.4mm.

[0037] Referring to Figure 1 , Figure 2 and Figure 6 As shown in steps S110 and S120, the hot forming stamping process is used to manufacture the hot forming steel piece 300, and the tensile strength of the hot forming steel piece 300 is controlled to be 1100MPa to 21000MPa, which exceeds the general tensile strength range that can be implemented by the traditional self-punching riveting process.

[0038] Referring to Figure 1 , Figure 2 and Figure 6 To this end, the die casting structure and the hot forming steel piece composite connection method additionally uses the cold stamping process to manufacture the transition connecting piece 200, and the tensile strength of the transition connecting piece 200 is controlled to be 500MPa to 1000MPa, so as to realize the self-punching riveting of the transition connecting piece 200 and the die casting structure 100 and the spot welding with the hot forming steel piece 300, and the thickness of the transition connecting piece 200 is controlled to be 1.2mm to 2.4mm, which can reduce the volume increase caused by the transition connecting piece 200.

[0039] Referring to Figure 1 , Figure 3 and Figure 7 As shown in step S200, the transition connecting piece 200 and the die casting structure 100 are clamped, and the transition connecting piece 200 is attached to the upper surface of the die casting structure 100, including the following steps: Step S210, the die casting structure 100 is formed with a connecting groove 110 adapted to the transition connecting piece 200, the transition connecting piece 200 is covered above the connecting groove 110, and the transition connecting piece 200 and the die casting structure 100 are overlapped along the edge of the connecting groove 110, and the overlapping size of the transition connecting piece 200 and the die casting structure 100 is controlled to be 20mm to 25mm.

[0040] Referring to Figure 1 , Figure 3 and Figure 7 , in step S210, in order to enhance the fitting degree of the die-cast structural member 100 and the transition connecting member 200, and reduce the manufacturing cost of the combination, the die-cast structural member and hot-formed steel member composite connecting method can form a connecting groove 110 at the edge of the die-cast structural member 100, the shape and size of the connecting groove 110 are adapted to the shape and size of the transition connecting member 200, the internal size of the connecting groove 110 is slightly smaller than the external size of the transition connecting member 200, so that the transition connecting member 200 can be lapped over the edge of the die-cast structural member 100 in the connecting groove 110.

[0041] Referring to Figure 1 , Figure 3 and Figure 7 , specifically, the die-cast structural member and hot-formed steel member composite connecting method can control the lap size of the transition connecting member 200 and the die-cast structural member 100 to be 20mm to 25mm, thereby providing sufficient space for the riveting of the rivet 600, under the riveting action of the external riveting gun, the rivet 600 can be riveted into the die-cast structural member 100 and the transition connecting member 200, to realize the self-punching riveting of the die-cast structural member 100 and the transition connecting member 200, to realize the stable connection of the transition connecting member 200 and the die-cast structural member 100. In Figure 1 , M represents the lap size of the transition connecting member 200 and the die-cast structural member 100.

[0042] Referring to Figure 2 , Figure 4 and Figure 7 , it can be understood that the die-cast structural member and hot-formed steel member composite connecting method in step S200 clamps the hot-formed steel member 300 and adheres the hot-formed steel member 300 to the upper surface of the transition connecting member 200, including the following steps: Step S220, lap the hot-formed steel member 300 with the edge of the transition connecting member 200, and control the lap size of the hot-formed steel member 300 and the transition connecting member 200 to be 16mm to 23mm.

[0043] Referring to Figure 2 , Figure 4 and Figure 7As shown in step S210, specifically, the composite connection method of the die-cast structural member and the hot-formed steel member can control the overlap size of the hot-formed steel member 300 and the transition connecting member 200 to 20-25 mm, thereby providing sufficient space for the welding of the rivet 600, and under the welding action of the welding gun of the external device, a welding nugget can be formed between the hot-formed steel member 300 and the transition connecting member 200, so as to realize the multi-point welding of the hot-formed steel member 300 and the transition connecting member 200, and to realize the stable connection of the transition connecting member 200 and the die-cast structural member 100. Figure 1 In the figure, L schematically represents the overlap size of the hot-formed steel member 300 and the transition connecting member 200.

[0044] As shown in Figure 1 , Figure 2 and Figure 8 , it can be understood that in step S300, the composite connection method of the die-cast structural member and the hot-formed steel member performs self-punching riveting of the die-cast structural member 100 and the transition connecting member 200 according to the self-punching riveting quality requirements, including the following steps: Step S310, multi-point self-punching riveting is performed on the overlap of the die-cast structural member 100 and the transition connecting member 200, so as to form a plurality of self-punching riveting points 400 at the overlap of the die-cast structural member 100 and the transition connecting member 200, and the interval between two adjacent self-punching riveting points 400 is 35-50 mm.

[0045] As shown in Figure 1 , Figure 2 and Figure 8 , in step S310, the composite connection method of the die-cast structural member and the hot-formed steel member can press the rivet 600 by the riveting gun, and under the mutual extrusion action of the rivet 600 and the riveting die, the overlap of the die-cast structural member 100 and the transition connecting member 200 is deformed and embedded into the riveting die, thereby realizing the riveting of the die-cast structural member 100 and the transition connecting member 200 by the rivet 600.

[0046] As shown in Figure 1 , Figure 2 and Figure 8 , the composite connection method of the die-cast structural member and the hot-formed steel member forms a plurality of self-punching riveting points 400 at the overlap of the die-cast structural member 100 and the transition connecting member 200 by means of multiple riveting, and the interval between two adjacent self-punching riveting points 400 is 35-55 mm, so as to realize the stable connection of the edges of the overlap of the die-cast structural member 100 and the transition connecting member 200, and the manufacturing is simpler and more convenient.

[0047] As shown in Figure 1 , Figure 2 and Figure 8As shown, it can be understood that the die casting structural member and hot forming steel member composite connection method in step S300, according to the self-piercing riveting quality requirements, the die casting structural member 100 and the transition connecting piece 200 are self-piercing riveted, including the following steps: Step S320, the interlocking value of the self-piercing riveting point 400 is controlled to be greater than or equal to 0.25mm, the undercut thickness is controlled to be greater than or equal to 0.1mm, and the head protrusion height is controlled to be-0.5mm to 0.3mm.

[0048] Referring to Figure 1 , Figure 2 and Figure 8 , specifically, Figure 3 a in the figure shows the interlocking value of the self-piercing riveting point 400, b shows the undercut thickness of the self-piercing riveting point 400, and c shows the head protrusion height of the self-piercing riveting point 400.

[0049] Referring to Figure 1 , Figure 2 and Figure 8 , that is, the die casting structural member and hot forming steel member composite connection method can control the interlocking value, undercut thickness and head protrusion height of the self-piercing riveting point 400 to ensure the embedding of the rivet 600 with the die casting structural member 100 and the transition connecting piece 200, and to ensure the connection quality of the self-piercing riveting of the die casting structural member 100 and the transition connecting piece 200, effectively solving the technical problem that the die casting structural member 100 cannot obtain a high-stability and high-reliability connection point when using self-piercing riveting connection between the die casting structural member 100 and the hot forming steel member 300 due to low local material elongation and large fluctuation.

[0050] Referring to Figure 1 , Figure 4 and Figure 9 , it can be understood that the die casting structural member and hot forming steel member composite connection method in step S400, according to the spot welding quality requirements, the hot forming steel member 300 and the transition connecting piece 200 are spot welded, including the following steps: Step S410, the lap joint of the transition connecting piece 200 and the hot forming steel member 300 is multi-point resistance spot welded, so that the lap joint of the transition connecting piece 200 and the hot forming steel member 300 is formed with a plurality of resistance welding points 500, and the interval between two adjacent resistance welding points 500 is 40mm to 60mm.

[0051] Referring to Figure 1 , Figure 4 and Figure 9As shown in step S410, the composite connection method of the die-cast structural member and the hot-formed steel member can be welding the transition connecting member 200 and the hot-formed steel member 300 by a welding gun, so that the lap joint of the transition connecting member 200 and the hot-formed steel member 300 forms a plurality of resistance welding points 500, and the lap joint of the transition connecting member 200 and the hot-formed steel member 300 is welded by multiple welding, that is, a plurality of resistance welding points 500 are formed, and the distance between two adjacent resistance welding points 500 is 40mm to 60mm, so as to realize the stable connection of the edge of the lap joint of the hot-formed steel member 300 and the transition connecting member 200, and the manufacturing is more simple and convenient.

[0052] Referring to Figure 1 , Figure 4 and Figure 9 , it can be understood that the composite connection method of the die-cast structural member and the hot-formed steel member in step S400 performs spot welding on the hot-formed steel member 300 and the transition connecting member 200 according to the spot welding quality requirements, including the following steps: Step S420, the nugget diameter of the resistance welding point 500 is controlled to be greater than or equal to 3.5 mm, the minimum penetration is controlled to be greater than or equal to 0.2mm, and t is the thickness of the thinner sheet of the transition connecting member 200 and the hot-formed steel member 300.

[0053] Referring to Figure 1 , Figure 4 and Figure 9 , specifically, Figure 4 , d indicates the nugget diameter of the resistance welding point 500, and e indicates the minimum penetration of the resistance welding point 500.

[0054] Referring to Figure 1 , Figure 4 and Figure 9 , that is, the composite connection method of the die-cast structural member and the hot-formed steel member can control the nugget diameter and the minimum penetration of the resistance welding point 500 to ensure that the welding gun penetrates the hot-formed steel member 300 and the transition connecting member 200, and ensure the connection quality of the welding of the transition connecting member 200 and the hot-formed steel member 300.

[0055] Referring to Figure 1 , Figure 2 and Figure 10 , it can be understood that the composite connection method of the die-cast structural member and the hot-formed steel member further includes the following steps before step S300 and step S400: Step S500, obtaining self-punching rivet process parameters meeting the self-punching rivet connection quality requirements through process test, the self-punching rivet process parameters including rivet 600 model, rivet 600 shape, rivet die shape, riveting force and riveting speed.

[0056] Step S600: obtaining spot welding process parameters that meet the spot welding quality requirements through process tests, wherein the spot welding process parameters include welding current, current waveform, welding time, holding time, pre-pressing time, electrode pressure, electrode diameter, and electrode shape.

[0057] Reference Figure 1 、 Figure 2 and Figure 10 As shown, the composite connection method of the die-cast structural part and the hot-formed steel part can formulate the self-punching riveting quality requirements required for self-punching riveting and the spot welding quality requirements required for resistance spot welding according to the sizes and types of the die-cast structural part 100, the transition connector 200 and the hot-formed steel part 300.

[0058] Reference Figure 1 、 Figure 2 and Figure 10 As shown, the composite connection method of the die-cast structural part and the hot-formed steel part can then be tested according to the process test method to test the self-piercing riveting process parameters required to meet the self-piercing riveting quality requirements. The self-piercing riveting process parameters include the rivet 600 model, the rivet 600 shape, the rivet die shape, the riveting force and the riveting speed. The composite connection method of the die-cast structural part and the hot-formed steel part can improve the stability and connection quality of the self-piercing riveting of the transition connector 200 and the die-cast structural part 100 by accurately defining the self-piercing riveting process parameters.

[0059] Reference Figure 1 、 Figure 2 and Figure 10 As shown, the composite connection method of the die-cast structural part and the hot-formed steel part can be tested according to the process test method to test the spot welding process parameters that meet the spot welding quality requirements. The spot welding process parameters include welding current, current waveform, welding time, holding time, pre-pressing time, electrode pressure, electrode diameter and electrode shape. The composite connection method of the die-cast structural part and the hot-formed steel part can improve the stability and connection quality of the resistance spot welding of the transition connector 200 and the hot-formed steel part 300 by accurately defining the spot welding process parameters.

[0060] Reference Figure 1 、 Figure 2 and Figure 11 As shown, it can be understood that the composite connection method of the die-cast structural part and the hot-formed steel part further includes the following steps: Step S700, selecting a plurality of self-piercing riveting points 400 and a plurality of resistance welding points 500 that are dispersed or evenly distributed on the assembly; Step S800, testing the self-pierce riveted points 400 according to the self-pierce riveting quality requirements, and testing the resistance welding points 500 according to the spot welding quality requirements; Step S900, when the plurality of self-piercing rivet joints 400 and the plurality of resistance welding joints 500 are all detected to be qualified, the corresponding connection technical parameters are determined.

[0061] Referring to Figure 1 , Figure 2 and Figure 11 , the composite connection method of the die-cast structural member and the hot-formed steel member can extract a first piece manufacturing assembly or a random assembly, and randomly select 3 self-piercing rivet joints 400 and 3 resistance welding joints 500 on the assembly. The 3 self-piercing rivet joints 400 and the 3 resistance welding joints 500 should be as dispersed or evenly distributed as possible on the extracted assembly.

[0062] Referring to Figure 1 , Figure 2 and Figure 11 , the composite connection method of the die-cast structural member and the hot-formed steel member can detect the selected self-piercing rivet joints 400 according to the self-piercing rivet quality requirements, or detect the resistance welding joints 500 according to the spot welding quality requirements. If the plurality of self-piercing rivet joints 400 and the plurality of resistance welding joints 500 are all detected to be qualified, it is determined that the corresponding connection technical parameters meet the production requirements, that is, the corresponding connection technical parameters are determined, and the connection technical parameters are input into the corresponding production equipment and applied to subsequent mass production, which is beneficial to improve the connection efficiency of the die-cast structural member 100 and the hot-formed steel member 300 of the same specification.

[0063] Referring to Figure 1 and Figure 2 , it can be understood that the following describes the implementation of the composite connection method of the die-cast structural member and the hot-formed steel member through a specific embodiment.

[0064] (Example 1) A certain passenger car plans to use an integrated die-cast rear floor (i.e. die-cast structural member 100), the connecting edge design wall thickness is 3.0 mm, and the manufacturing material is a non-heat-treated die-cast aluminum alloy material THAS-1. The hot-formed middle channel part (hot-formed steel member 300) connected thereto is made of 1.8 mm thick FC950 / 1500HSAS hot-formed aluminum-silicon plated steel sheet. In view of the difficulty of achieving high stability and high quality connection between the above two parts by self-piercing riveting, a new type of connection technology suitable for mass production is developed based on product structure optimization and matching.

[0065] Referring to Figure 1 and Figure 2 , the connection model is composed of an integrated die-cast rear floor part (i.e. die-cast structural member 100), a middle channel part (i.e. hot-formed steel member 300), and an advanced high-strength steel transition connecting piece 200 (i.e. transition connecting piece 200). The types, specifications, and surface states of the materials used in the integrated die-cast rear floor part and the middle channel part are the same as before the advanced high-strength steel transition connecting piece 200 is not set.

[0066] Referring to Figure 1 and Figure 2 , a test sample is manufactured based on the connection model. Among them, the integrally die-cast rear floor part is manufactured by high-vacuum die-casting process; the middle channel part is manufactured by hot forming stamping process; the advanced high-strength steel transition connecting piece 200 is manufactured by cold stamping process. The connecting edge of the integrally die-cast rear floor has a wall thickness of 3.0 mm, and the manufacturing material is a heat treatment-free die-cast aluminum alloy material THAS-1. The manufacturing material of the middle channel part is a 1.8 mm thick FC950 / 1500 HSAS hot forming aluminum-silicon plated steel plate, and the tensile strength thereof is about 1500 MPa. The manufacturing material of the advanced high-strength steel transition connecting piece 200 is a FC420 / 780 DP with a thickness of 2.0 mm, and the tensile strength thereof is about 780 MPa.

[0067] Referring to Figure 1 and Figure 2 , the integrally die-cast rear floor part, the middle channel part and the advanced high-strength steel transition connecting piece 200 are assembled, clamped and positioned according to the actual assembly position requirements of the connection model, so as to ensure appropriate riveting and welding gun space. The assembly position relationship is that the integrally die-cast rear floor part is located at the bottom layer of the connection model, the middle channel part is located at the uppermost layer of the connection model, and the advanced high-strength steel transition connecting piece 200 is located at the middle layer and is in good shape fit with the integrally die-cast rear floor part and the middle channel part.

[0068] Referring to Figure 1 and Figure 2 , based on the strength performance index requirements of the connection points, the self-piercing riveting quality requirements and the spot welding quality requirements in the connection model are locked. For the self-piercing riveting quality requirements, the interlocking value a should satisfy: a≥0.25 mm, the undercut thickness b should satisfy: b≥0.1 mm, and the head height c should satisfy: -0.5 mm≤c≤0.3 mm. For the spot welding quality requirements, the nugget diameter d should satisfy: d≥4.7 mm, and the minimum penetration f should satisfy: f≥0.2 mm. The composite connection method of the die-cast structure and the hot-formed steel part obtains the process parameters satisfying the self-piercing riveting and spot welding quality requirements through process tests. The connection equipment used in the process tests is the same as the production equipment.

[0069] Referring to Figure 1 and Figure 2 , the self-piercing riveting process parameters include the rivet 600 model and shape, the rivet die shape, the riveting force and the riveting speed. The resistance spot welding process parameters include the welding current, the current waveform, the welding time, the holding time, the pre-pressing time, the electrode pressure, the electrode diameter and the shape.

[0070] Referring to Figure 1 and Figure 2As shown, based on the acquired self-punching rivet process parameters, the connection between the integrally die-cast rear floor part and the advanced high-strength steel transition connector 200 is carried out according to the number and arrangement of the self-punching rivet points 400 in the connection model. The integrally die-cast rear floor part and the advanced high-strength steel transition connector 200 are connected by self-punching rivet, and the lap joint size M = 23 mm; the self-punching rivet points 400 are arranged at intervals of 45 mm.

[0071] Referring to Figure 1 and Figure 2 As shown, based on the acquired resistance spot welding process parameters, the connection between the middle channel part and the advanced high-strength steel transition connector 200 is carried out according to the number and arrangement of the resistance welding spots 500 in the connection model. The advanced high-strength steel transition connector 200 and the middle channel part are connected by resistance spot welding, and the lap joint size L = 20 mm. The resistance welding spots 500 are arranged at intervals of 50 mm.

[0072] Referring to Figure 1 and Figure 2 As shown, the first piece or a random sample is extracted, and 3 self-punching rivet points 400 and 3 resistance welding spots 500 are randomly selected thereon to be tested according to the self-punching rivet quality requirements and the spot welding quality requirements, respectively. The 3 self-punching rivet points 400 and the 3 resistance welding spots 500 should be as dispersed or evenly distributed as possible in the sample. If the test results meet the self-punching rivet quality requirements and the spot welding quality requirements, respectively, the corresponding connection technical parameters are locked, input into the corresponding production equipment, and applied to subsequent mass production.

[0073] Referring to Figure 1 and Figure 2 As shown, it can be understood that the following describes the implementation of the composite connection method of the die-cast structural part and the hot-formed steel part through another specific embodiment.

[0074] (Example 2) A passenger car plans to use an integrally die-cast front engine compartment (die-cast structural part 100), and the connecting edge design wall thickness is 3.5 mm, and the manufacturing material is a non-heat-treated die-cast aluminum alloy material C611. The hot-formed front apron lower plate part (hot-formed steel part 300) connected thereto is made of 1.6 mm thick FC1200 / 1800HSAS hot-formed aluminum-silicon coated steel sheet. In view of the difficulty of achieving high stability and high quality connection between the above two parts by self-punching rivet, a new type of connection technology suitable for mass production is developed based on product structure optimization and matching to meet the connection quality requirements.

[0075] Referring to Figure 1 and Figure 2As shown, the connection model is composed of three parts, i.e., an integrally die-cast front engine compartment part (i.e., the die-cast structural part 100), a front apron lower plate part (i.e., the hot-formed steel part 300), and an advanced high-strength steel transition connecting part 200 (i.e., the transition connecting part 200). The material types, specifications, and surface states of the integrally die-cast front engine compartment part and the front apron lower plate part are the same as before the advanced high-strength steel transition connecting part 200 is not arranged.

[0076] Referring to Figure 1 and Figure 2 As shown, the test sample is manufactured based on the connection model. Among them, the integrally die-cast front engine compartment part is manufactured by high-vacuum die casting process; the front apron lower plate part is manufactured by hot forming stamping process; and the advanced high-strength steel transition connecting part 200 is manufactured by cold stamping process. The connecting edge of the integrally die-cast front engine compartment part is designed to have a wall thickness of 3.5 mm, and the manufacturing material is a non-heat-treated die-cast aluminum alloy material C611. The manufacturing material of the front apron lower plate part is a 1.6 mm thick FC1200 / 1800HSAS hot-formed aluminum-silicon coated steel plate, and the tensile strength thereof is about 800 MPa. The manufacturing material of the advanced high-strength steel transition connecting part 200 is selected to be a FC650 / 980DP with a thickness of 1.6 mm, and the tensile strength thereof is about 80 MPa.

[0077] Referring to Figure 1 and Figure 2 As shown, the integrally die-cast front engine compartment part, the front apron lower plate part, and the advanced high-strength steel transition connecting part 200 are assembled, clamped, and positioned according to the actual assembly position requirements of the connection model by using appropriate welding tooling, so as to ensure appropriate riveting and welding gun space. The assembly position relationship is that the integrally die-cast front engine compartment part is located at the bottom layer of the connection model, the front apron lower plate part is located at the uppermost layer of the connection model, and the advanced high-strength steel transition connecting part 200 is located at the middle layer and forms a good shape fit with the integrally die-cast front engine compartment part and the front apron lower plate part.

[0078] Referring to Figure 1 and Figure 2 As shown, the self-piercing riveting quality requirements and the spot welding quality requirements in the connection model are locked based on the connection point strength performance index requirements. For the self-piercing riveting quality requirements, the interlocking value a should satisfy a≥0.25 mm, the undercut thickness b should satisfy b≥0.1 mm, and the head height c should satisfy -0.5 mm≤c≤0.3 mm. For the spot welding quality requirements, the nugget diameter d should satisfy d≥4.4 mm, and the minimum penetration f should satisfy f≥0.2 mm. The process parameters satisfying the self-piercing riveting and spot welding quality requirements are respectively obtained through process tests, and the connection equipment used in the process tests is the same as the production equipment.

[0079] Referring to Figure 1 and Figure 2As shown, the self-piercing rivet process parameters include rivet 600 model and shape, rivet die shape, riveting force, and riveting speed. The resistance spot welding process parameters include welding current, current waveform, welding time, holding time, pre-pressing time, electrode pressure, electrode diameter and shape.

[0080] Referring to Figure 1 and Figure 2 As shown, based on the acquired self-piercing rivet process parameters, the connection between the integrated die-cast front engine compartment part and the advanced high-strength steel transition connector 200 is carried out according to the number and arrangement of the self-piercing rivet points 400 in the connection model. The integrated die-cast front engine compartment part and the advanced high-strength steel transition connector 200 are connected by self-piercing riveting, and the amount of overlapping edge size M = 23 mm; the self-piercing rivet points 400 are arranged at an interval of 40 mm.

[0081] Referring to Figure 1 and Figure 2 As shown, based on the acquired resistance spot welding process parameters, the connection between the front apron lower plate part and the advanced high-strength steel transition connector 200 is carried out according to the number and arrangement of the resistance welding points 500 in the connection model. The advanced high-strength steel transition connector 200 and the front apron lower plate part are connected by resistance spot welding, and the resistance welding points 500 are arranged at an interval of 55 mm.

[0082] Referring to Figure 1 and Figure 2 As shown, the first piece or a random sample is extracted, and 3 self-piercing rivet points 400 and 3 resistance welding points 500 are randomly selected thereon for detection according to the self-piercing rivet quality requirements and the spot welding quality requirements. The 3 self-piercing rivet points 400 and the 3 resistance welding points 500 should be as dispersed or uniformly distributed as possible in the sample. If the detection results meet the self-piercing rivet quality requirements and the spot welding quality requirements, the corresponding connection technical parameters are locked, input into the corresponding production equipment, and applied to subsequent mass production.

[0083] Referring to Figure 1 and Figure 2 As shown, it can be understood that the following describes the implementation of the method for composite connection of die-cast structural parts and hot-formed steel parts through another specific embodiment.

[0084] (Example 3) A passenger car plans to use an integrated die-cast front engine compartment (i.e., die-cast structural component 100). The design wall thickness of its connecting edge is 3.5 mm, and the manufacturing material is die-cast magnesium alloy material AS41B. The hot-formed front dash lower panel part (i.e., hot-formed steel component 300) connected to it is manufactured from 1.5 mm thick FC1300 / 2000HSAS hot-forming aluminum-silicon coated steel plate. In order to solve the problem of using self-pierce riveting to achieve a highly stable and high-quality connection between the above two parts, a new connection technology suitable for mass production that meets the connection quality requirements is developed based on product structure optimization and matching.

[0085] Reference Figure 1 and Figure 2 As shown, the connection model consists of three parts: an integral die-cast front nacelle component (i.e., die-cast structural component 100), a dash lower panel component (i.e., hot-formed steel component 300), and an advanced high-strength steel transition piece 200 (i.e., transition piece 200). The material type, specifications, and surface finish of the integral die-cast front nacelle component and dash lower panel component are the same as those without the advanced high-strength steel transition piece 200.

[0086] Reference Figure 1 and Figure 2 As shown, test specimens were manufactured based on the connection model. The one-piece die-cast front nacelle component was manufactured using a high-vacuum die-casting process; the dash lower panel component was manufactured using a hot stamping process; and the advanced high-strength steel transition piece 200 was manufactured using a cold stamping process. The one-piece die-cast front nacelle component's connecting edge had a designed wall thickness of 3.5 mm and was manufactured from the die-cast magnesium alloy AS41B. The dash lower panel component was manufactured from 1.5 mm thick FC1300 / 2000HSAS hot-formed aluminum-silicon coated steel sheet with a tensile strength of approximately 2000 MPa. The advanced high-strength steel transition piece 200 was manufactured from 1.6 mm thick FC420 / 780DP, which has a tensile strength of approximately 780 MPa.

[0087] Reference Figure 1 and Figure 2 As shown, suitable welding fixtures are used to assemble, clamp, and position the integral die-cast front nacelle components, the dash lower panel components, and the advanced high-strength steel transition piece 200 according to the actual assembly position requirements of the connection digital model, ensuring adequate clearance for riveting and welding. The assembly positional relationship is as follows: the integral die-cast front nacelle components are located at the bottom layer of the connection model, and the dash lower panel components are located at the top layer. The advanced high-strength steel transition piece 200 is located in the middle layer, forming a good form fit with the integral die-cast front nacelle components and the dash lower panel components.

[0088] Based on the joint strength performance index requirements, the self-piercing riveting quality requirements and the spot welding quality requirements in the locking joint model are locked. For the self-piercing riveting quality requirements, the interlocking value a should satisfy: a≥0.25mm, the undercut thickness b should satisfy: b≥0.1mm, and the head height c should satisfy: -0.5mm≤c≤0.3mm. For the spot welding quality requirements, the nugget diameter d should satisfy: d≥4.3mm, and the minimum penetration f should satisfy: f≥0.2mm. The process parameters satisfying the self-piercing riveting and spot welding quality requirements are obtained through process tests, and the connecting equipment used in the process tests is the same as the production equipment.

[0089] Referring to Figure 1 and Figure 2 , the self-piercing riveting process parameters include the rivet 600 model and shape, the rivet die shape, the riveting force, and the riveting speed. The resistance spot welding process parameters include the welding current, the current waveform, the welding time, the holding time, the pre-pressing time, the electrode pressure, and the electrode diameter and shape.

[0090] Referring to Figure 1 and Figure 2 , based on the obtained self-piercing riveting process parameters, the connection between the integrally die-cast front cabin part and the advanced high-strength steel transition connecting piece 200 is carried out according to the number and arrangement of the self-piercing riveting points 400 in the connection model. The integrally die-cast front cabin part and the advanced high-strength steel transition connecting piece 200 are connected by self-piercing riveting, and the overlap amount size M=22mm, and the self-piercing riveting points 400 are arranged at an interval of 45mm.

[0091] Referring to Figure 1 and Figure 2 , based on the obtained resistance spot welding process parameters, the connection between the front apron lower panel part and the advanced high-strength steel transition connecting piece 200 is carried out according to the number and arrangement of the resistance welding points 500 in the connection model. The advanced high-strength steel transition connecting piece 200 and the front apron lower panel part are connected by resistance spot welding, and the overlap amount size L=20mm. The resistance welding points 500 are arranged at an interval of 50mm.

[0092] Referring to Figure 1 and Figure 2 , a first piece or a random sample is extracted, and 3 self-piercing riveting points 400 and 3 resistance welding points 500 are randomly selected thereon for detection according to the self-piercing riveting quality requirements and the spot welding quality requirements. The 3 self-piercing riveting points 400 and the 3 resistance welding points 500 should be as dispersed or uniformly distributed as possible in the sample. If the detection results all satisfy the self-piercing riveting quality requirements and the spot welding quality requirements, the corresponding connection technology parameters are locked, input into the corresponding production equipment, and applied to subsequent mass production. The connection technology parameters include the self-piercing riveting process parameters, the self-piercing riveting quality requirements, the spot welding quality requirements, and the spot welding process parameters.

[0093] Those skilled in the art will appreciate that embodiments of the present application can be readily used as a method, a system or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer-readable program code.

[0094] The present application is described in terms of flowcharts and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the present application. It will be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing system or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowcharts and / or block diagrams block or blocks. Figure 1 one or more functions specified in one or more of the flowchart or block diagrams. Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure 1 Figure 2 Figure means for carrying out each of the one or more functions specified in the flowchart or block diagram block or blocks.

[0095] The embodiments of the present application described above are merely intended to illustrate the present application, but the present application is not limited to the above-described embodiments, and various changes can be made within the scope of knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A composite connection method of a die-cast structural part and a hot-formed steel part, characterized in that: include: According to product requirements, vacuum die-casting process is used to manufacture die-cast structural parts, hot-formed steel parts are manufactured by hot-forming stamping process, and transition connectors are manufactured by cold stamping process; Clamping the transition piece and the die-cast structural part, and attaching the transition piece to the upper surface of the die-cast structural part, clamping the hot-formed steel part, and attaching the hot-formed steel part to the upper surface of the transition piece; Performing self-piercing riveting on the die-cast structural component and the transition connector according to the self-piercing riveting quality requirements, so that the transition connector and the die-cast structural component achieve multi-point riveting in the contact area; The hot-formed steel part and the transition piece are spot-welded according to the spot welding quality requirements, so that the fitting areas of the hot-formed steel part and the transition piece are multi-spot welded, so that the die-cast structural part, the transition piece and the hot-formed steel part are connected into a combination.

2. The composite connection method of a die-cast structural part and a hot-formed steel part according to claim 1, characterized in that: The step of clamping the transition piece and the die-cast structural part and attaching the transition piece to the upper surface of the die-cast structural part comprises: The die-cast structural component is formed with a connecting groove that is adapted to the transition connecting component. The transition connecting component is covered above the connecting groove, and the transition connecting component and the die-cast structural component are overlapped along the edge of the connecting groove. The overlap size of the transition connecting component and the die-cast structural component is controlled to be 20 mm to 25 mm.

3. The composite connection method of a die-cast structural part and a hot-formed steel part according to claim 1, characterized in that: The step of clamping the hot-formed steel part and attaching the hot-formed steel part to the upper surface of the transition piece includes: The edges of the hot-formed steel part and the transition connector are overlapped, and the overlap size of the hot-formed steel part and the transition connector is controlled to be 16 mm to 23 mm.

4. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 2, characterized in that: The self-piercing riveting of the die-cast structural component and the transition connector according to the self-piercing riveting quality requirements includes: Multi-point self-piercing riveting is performed on the overlap between the die-cast structural component and the transition connector, so that multiple self-piercing riveting points are formed at the overlap between the die-cast structural component and the transition connector, and the interval between two adjacent self-piercing riveting points is 35mm to 50mm.

5. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 4, characterized in that: The self-piercing riveting of the die-cast structural component and the transition connector according to the self-piercing riveting quality requirements includes: The interlocking value of the self-piercing riveting points is controlled to be greater than or equal to 0.25 mm, the undercut thickness is controlled to be greater than or equal to 0.1 mm, and the head protrusion height is controlled to be -0.5 mm to 0.3 mm.

6. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 3, characterized in that: Spot welding the hot-formed steel part and the transition piece according to spot welding quality requirements includes: Multi-point resistance spot welding is performed on the overlap between the transition connector and the hot-formed steel part, so that multiple resistance welding points are formed at the overlap between the transition connector and the hot-formed steel part, and the interval between two adjacent resistance welding points is 40 mm to 60 mm.

7. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 6, characterized in that: Spot welding the hot-formed steel part and the transition piece according to spot welding quality requirements includes: The diameter of the weld core of the resistance welding point is controlled to be greater than or equal to 3.5 mm, the minimum penetration depth is controlled to be greater than or equal to 0.2 mm, and t is the thickness of the thinner sheet in the transition connector and the hot-formed steel part.

8. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 1, characterized in that: The method of manufacturing hot-formed steel parts by using a hot forming stamping process and manufacturing transition connectors by using a cold stamping process includes: The hot-formed steel part is manufactured by the hot-forming stamping process, and the tensile strength of the hot-formed steel part is controlled to be 1100 MPa to 2100 MPa; The cold stamping process is used to manufacture the transition connector, and the tensile strength of the transition connector is controlled to be 500 MPa to 1000 MPa, and the thickness is controlled to be 1.2 mm to 2.4 mm.

9. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 1, characterized in that: The composite connection method of the die-cast structural component and the hot-formed steel component further comprises the following steps before the die-cast structural component and the transition connector are self-piercing riveted according to the self-piercing riveting quality requirements: Obtaining self-piercing riveting process parameters that meet the self-piercing riveting quality requirements through process tests, wherein the self-piercing riveting process parameters include rivet model, rivet shape, rivet die shape, riveting force, and riveting speed; The spot welding process parameters that meet the spot welding quality requirements are obtained through process tests, and the spot welding process parameters include welding current, current waveform, welding time, holding time, pre-pressing time, electrode pressure, electrode diameter and electrode shape.

10. The composite connection method of a die-cast structural component and a hot-formed steel component according to claim 1, characterized in that: The composite connection method of the die-cast structural part and the hot-formed steel part further includes: Selecting a plurality of self-piercing riveting points and a plurality of resistance welding points that are dispersed or evenly distributed on the assembly; Testing the self-pierce riveting points according to the self-pierce riveting quality requirements, and testing the resistance welding points according to the spot welding quality requirements; When the plurality of self-piercing riveting points and the plurality of resistance welding points are all qualified in the inspection, the corresponding connection technical parameters are determined.

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