Manufacturing method of steel-aluminum composite stamping and welding structure

Abstract

The invention discloses a manufacturing method of a steel-aluminum composite stamping and welding structure. The manufacturing method comprises the following steps: preparing an aluminum stamping part; forming a convex tongue flange and a convex tongue flange hole on the landing edge of the aluminum stamping part; taking an aluminum / steel composite plate with the thickness equal to the height of the convex tongue flange as a raw material, and cutting according to the shape of a convex tongue flange hole to prepare an aluminum / steel composite plate insert; the aluminum / steel composite plate insert is embedded into the convex tongue flange hole, and the surface of a steel layer of the aluminum / steel composite plate insert is flush with the surface of the landing edge of the aluminum stamping part; welding the aluminum layer of the aluminum / steel composite plate insert with the convex tongue flange; a plurality of blind holes are machined in the aluminum layer of the aluminum / steel composite board insert, and the depth of the blind holes is equal to the difference between the thickness of the aluminum / steel composite board insert and the thickness of the steel layer of the aluminum / steel composite board insert; preparing a steel stamping part; welding the steel layer of the aluminum / steel composite plate insert corresponding to the bottom surface of each blind hole with the landing edge of the steel stamping part to manufacture a steel-aluminum composite stamping welding structure; and the blind holes are filled with structural adhesive. By means of the method, high-quality manufacturing of the steel-aluminum composite stamping and welding structure can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for connecting a steel stamping part and an aluminum stamping part, in particular to a method for manufacturing a steel-aluminum composite stamping and welding structure. BACKGROUND

[0002] Under the background of the development trend of automobile lightweight, steel-aluminum hybrid body is widely adopted. As the main connection method of traditional steel body stamping parts, resistance spot welding is difficult to adapt to steel-aluminum welding, so the automobile industry has developed new connection methods such as self-piercing riveting technology, flow-drilling screw technology, and press-in technology to replace resistance spot welding to manufacture steel-aluminum hybrid body.

[0003] Self-piercing riveting technology occupies a key and main position in the field of steel-aluminum hybrid body. This connection technology penetrates the upper layer of material through the rivet to form an interlocking structure in the lower layer of material, which is a cold connection method without heat input. Self-piercing riveting fundamentally avoids the generation of brittle phase at the steel-aluminum connection interface, ensuring the reliability and firmness of the connection point. However, compared with traditional resistance spot welding, self-piercing riveting still has great disadvantages, which have six main reasons. Firstly, self-piercing riveting requires a special self-piercing riveting robot workstation, high-precision servo riveting gun, and a complex rivet feeding system, as well as high-cost consumables such as punches, blank holders, and concave dies. When connecting high-strength materials such as high-strength steel, the wear is very fast and needs to be replaced frequently. Secondly, self-piercing riveting requires a very small gap between the workpieces, which puts high requirements on the quality of stamping parts and fixture design. Thirdly, self-piercing riveting requires sufficient operating space on both sides of the workpiece, which is almost impossible to achieve in areas with dense structures and narrow spaces. Fourthly, the quality of self-piercing riveting is sensitive to pressure, speed, stroke, and other parameters, which need to be accurately set and verified according to specific material combinations, sheet thickness, and coatings. Any change (such as changing the material supplier) may require re-adjustment of the process. Fifthly, the total sheet thickness range that can be effectively connected by self-piercing riveting is limited. Too thin material combinations may not form a stable interlocking button, and too thick combinations may result in "rivet not penetrating" or not fully forming. Sixthly, self-piercing riveting is difficult to detect, because the core quality indicator of self-piercing riveting is the shape and integrity of the "interlocking button" formed by the rivet in the lower layer of material, and there is currently a lack of non-destructive testing technology for high-reliability detection.

[0004] Obviously, it is a necessary measure to replace resistance spot welding with self-piercing riveting technology to connect steel and aluminum in steel-aluminum hybrid body. Although the current flow-drilling screw technology and press-in technology overcome some of the shortcomings of self-piercing riveting technology, they have more limitations than self-piercing riveting. SUMMARY

[0005] Invention purposes: The purpose of the present application is to provide a manufacturing method of a steel-aluminum composite stamping welding structure, which introduces a steel-aluminum composite plate into the flange of an aluminum stamping part through the fusion of the tongue flange forming and laser self-welding technology, and then realizes the high-quality manufacturing of the steel-aluminum composite stamping welding structure through resistance spot welding.

[0006] Technical scheme: The present application comprises the following steps:

[0007] Step 1: preparing an aluminum stamping part;

[0008] Step 2: forming a tongue flange and a tongue flange hole on the flange of the aluminum stamping part;

[0009] Step 3: cutting the aluminum / steel composite plate insert according to the shape of the tongue flange hole with the aluminum / steel composite plate as raw material, and the thickness of the aluminum / steel composite plate is equal to the height of the tongue flange;

[0010] Step 4: embedding the aluminum / steel composite plate insert into the tongue flange hole, and the surface of the steel layer of the aluminum / steel composite plate insert is flush with the surface of the flange of the aluminum stamping part;

[0011] Step 5: welding the aluminum layer of the aluminum / steel composite plate insert with the tongue flange;

[0012] Step 6: processing a plurality of blind holes in the aluminum layer of the aluminum / steel composite plate insert, and the depth of the blind hole is equal to the difference between the thickness of the aluminum / steel composite plate insert and the thickness of the steel layer of the aluminum / steel composite plate insert;

[0013] Step 7: preparing a steel stamping part;

[0014] Step 8: welding the steel layer of the aluminum / steel composite plate insert corresponding to the bottom surface of each blind hole and the flange of the steel stamping part to form a steel-aluminum composite stamping welding structure;

[0015] Step 9: filling the structure glue into each blind hole.

[0016] The step 2 is specifically: first, opening a rectangular hole in the middle of the flange of the aluminum stamping part, cutting 45° release grooves at the four corners of the rectangular hole, and finally folding and bending the tongue outward by 90° to form the tongue flange and the tongue flange hole.

[0017] The height of the tongue flange is not less than (3n+1) mm, wherein n=max (the thickness of the steel stamping part, the thickness of the aluminum stamping part).

[0018] The material and thickness of the steel layer of the aluminum / steel composite plate are consistent with the material and thickness of the steel stamping part.

[0019] The single-sided gap between the aluminum / steel composite plate insert and the tongue flange is less than or equal to 30 μm.

[0020] The laser self-fusion welding is used when the aluminum layer of the aluminum / steel composite plate insert is welded with the tongue flange, and the penetration of the laser self-fusion welding seam is not greater than (M - t - 0.5) mm, wherein M is the thickness of the aluminum / steel composite plate insert, and t is the plate thickness of the steel stamping part.

[0021] The minimum diameter of the blind hole is (4 + 3.5) mm, wherein t is the plate thickness of the steel stamping part.

[0022] The pitch of the blind hole is greater than or equal to 22 , and t is the plate thickness of the steel stamping part.

[0023] The welding method used in the step 8 is resistance spot welding.

[0024] When the resistance spot welding is used, one electrode presses the lap of the steel stamping part, and the other electrode extends into the blind hole and presses the steel layer of the aluminum / steel composite plate insert.

[0025] Beneficial effects: The steel-aluminum composite plate with a high-strength bonding interface is introduced into the lap of the aluminum stamping part by fusing the tongue flange forming, laser self-fusion welding and other technologies, so that the steel-aluminum connection is converted into a steel-steel connection without damaging the mechanical properties of the aluminum stamping part, and then the high-quality manufacturing of the steel-aluminum composite stamping and welding structure is realized through resistance spot welding; the steel-aluminum hybrid vehicle body can be directly produced on the steel vehicle body assembly production line, and the production cost is greatly reduced; the application range is wide, and the manufacturing of stamping and welding structures composed of various difficult-to-weld dissimilar materials can be applied. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of an aluminum stamping part;

[0027] Figure 2 is a schematic diagram of a steel-aluminum composite plate (in the figure, aluminum is represented by no color, steel is represented by gray, and black represents contour lines or welding formation area, the same below);

[0028] Figure 3 is a schematic diagram of the aluminum stamping part after the hole is opened on the lap (the left side is an elevation view, and the right side is a plan view);

[0029] Figure 4 is a schematic diagram of the aluminum stamping part after the release groove is cut on the lap (the left side is an elevation view, and the right side is a plan view);

[0030] Figure 5 is a schematic diagram of the aluminum stamping part after the tongue flange and the tongue flange hole are prepared by bending the lap (the left side is an elevation view, and the right side is a plan view;

[0031] Figure 6Fig. 1 is a schematic view of the aluminum stamping piece with the steel-aluminum composite piece inserted into the flange hole of the flange tongue of the aluminum stamping piece (the left side is a front view and the right side is a top view) ;

[0032] Figure 7 Fig. 2 is a schematic view of the steel-aluminum composite piece after laser self-flux welding with the flange tongue flange of the aluminum stamping piece (the left side is a front view and the right side is a top view) ;

[0033] Figure 8 Fig. 3 is a schematic view of the steel-aluminum composite piece after the aluminum side of the steel-aluminum composite piece is opened to form a blind hole (the left side is a front view and the right side is a top view) ;

[0034] Figure 9 Fig. 4 is a schematic view of the aluminum stamping piece after resistance spot welding with the steel stamping piece;

[0035] Figure 10 Fig. 5 is a schematic view of the steel-aluminum composite piece after the blind hole is filled with structural adhesive. DETAILED DESCRIPTION

[0036] The present application will be further described below with reference to the accompanying drawings.

[0037] Example 1

[0038] As shown in Fig. 1, the manufacturing method of the steel-aluminum composite stamping and welding structure of the present embodiment includes the following steps: Figures 1-10

[0039] Step 1: preparing the aluminum stamping piece as shown in Fig. 1. Figure 1

[0040] The aluminum stamping piece 1 is prepared by using blanking, drawing, bending and other sheet forming methods.

[0041] Step 2: forming the flange tongue flange and the flange tongue hole on the flange of the aluminum stamping piece, as shown in Fig. 2. Figures 3-5

[0042] The flange tongue flange 3 and the flange tongue hole 4 are formed on the flange 2 of the aluminum stamping piece by using the methods of opening a hole, cutting a release groove and bending. That is, a rectangular hole 18 is first opened in the middle of the flange 2 of the aluminum stamping piece, 45° release grooves 19 are cut at the four corners of the rectangular hole 18, and finally the flange tongue 20 is folded and bent 90° to form the flange tongue flange 3 and the flange tongue hole 4. In order to ensure the strength of the laser self-flux welding joint between the aluminum / steel composite piece 5 and the flange tongue flange 3, and to ensure that the heat during laser self-flux welding does not affect the structure and performance of the non-flange tongue flange 3 part of the flange 2 of the aluminum stamping piece, the height of the flange tongue flange 3 is required to be not less than (3n+1) mm, n=max (the thickness of the sheet material of the steel stamping piece, the thickness of the sheet material of the aluminum stamping piece), and the height of the flange tongue flange 3 refers to the vertical distance from the original upper surface (i.e. the upper surface not affected by bending) of the flange 2 of the aluminum stamping piece to the end surface of the flange tongue flange, which is the sum of the thickness of the flange 2 of the aluminum stamping piece itself and the height of the vertical edge formed by the flange tongue flange 3.​​​

[0043] If the overheated zone of the welding joint directly acts on the lap 2 of the aluminum stamping part, the mechanical properties of the lap 2 will be greatly reduced, which is not allowed in the steel-aluminum composite stamping and welding structure. The tongue flange 3 and the tongue flange hole 4 are prepared on the lap 2 of the aluminum stamping part, and the necessary welding joint is transferred to the tongue flange 3 perpendicular to the surface of the lap 2. In order to further ensure that the mechanical properties of the lap 2 of the aluminum stamping part are not affected, in addition to using the laser self-melting welding method with small heat-affected zone, the minimum value of the height of the tongue flange 3 must be specified. The present application finds that when the height of the tongue flange 3 is not less than (3n+1) mm, through suitable laser self-melting welding seam 7 depth control, it can be ensured that the heat of laser self-melting welding will not cause any performance impact on the lap 2, and it can ensure the laser self-melting welding strength of the subsequent aluminum / steel composite plate insert 5 and the tongue flange 3.

[0044] Step 3: Cut the aluminum / steel composite plate with a thickness equal to the height of the tongue flange to prepare the aluminum / steel composite plate insert according to the shape of the tongue flange hole.

[0045] As shown in Figure 2 The aluminum / steel composite plate 8 is prepared by explosion welding. Because the aluminum / steel explosion composite plate 8 forms a metallurgical bonding + mechanical interlocking bonding interface, and to a great extent avoids the formation of Al-Fe intermetallic compound, so the interface bonding strength is quite high. The high interface bonding strength of the aluminum / steel explosion composite plate 8 is the basic guarantee of high-quality connection of the steel-aluminum composite stamping and welding structure 9.

[0046] Because the steel layer 10 of the subsequent aluminum / steel composite plate needs to be resistance spot welded with the lap 11 of the steel stamping part, in the case that the two steel plates to be welded are consistent in material and thickness, the resistance spot welding quality is best, and the welding process is also the simplest. Therefore, the material and thickness of the steel layer 10 of the aluminum / steel composite plate selected by the present application are consistent with the material and thickness of the steel stamping part 6 plate.

[0047] For the aluminum layer 12 of the aluminum / steel composite plate, a double-layer structure is preferred, the thicker layer at the bottom is the same material as the aluminum stamping part 1, and the thinner layer is located between the thicker layer and the steel layer, and the material is pure aluminum. Pure aluminum can play the role of an intermediate layer.

[0048] The aluminum / steel composite plate 8 with a thickness equal to the height of the tongue flange 3 is selected, and the aluminum / steel composite plate 8 is cut into an aluminum / steel composite plate insert 5 according to the shape of the tongue flange hole 4 by water cutting or wire spark cutting, etc. Figure 6As shown, after the aluminum / steel composite insert 5 is inserted into the tongue flange hole 4 on the flange 2 of the aluminum stamping, it just fills the entire tongue flange hole 4 completely. In order to ensure the welding quality of the subsequent laser self-fluxing welding and the surface forming of the laser self-fluxing welding seam 7, the single-sided gap between the aluminum / steel composite insert 5 and the tongue flange 3 prepared by cutting needs to be less than or equal to 30 μm.

[0049] Step 4: Insert the aluminum / steel composite insert into the tongue flange hole, and the steel side surface of the aluminum / steel composite insert is flush with the surface of the flange of the aluminum stamping.

[0050] Insert the aluminum / steel composite insert 5 into the tongue flange hole 4 on the flange 2 of the aluminum stamping, and the steel layer surface of the aluminum / steel composite insert 5 is flush with the surface of the flange 2 of the stamping. Because the thickness of the aluminum / steel composite insert 5 (i.e. the thickness of the aluminum / steel composite plate 8) is equal to the height of the tongue flange 3, the bottom surface of the aluminum layer of the aluminum / steel composite insert 5 is also flush with the bottom of the tongue flange 3.

[0051] Step 5: Weld the aluminum layer of the aluminum / steel composite insert and the tongue flange by laser self-fluxing welding, as shown in Figure 7 .

[0052] Laser self-fluxing welding has the advantages of high energy density, small heat input, small deformation, high speed, high automation degree and no need for welding wire, and is very suitable for welding between the aluminum layer 14 of the aluminum / steel composite insert and the tongue flange 3 on the flange 2 of the aluminum stamping. By controlling the welding line energy of laser welding, the laser self-fluxing welding seam 7 has a penetration depth of not more than (M - t - 0.5) mm, where M is the thickness of the aluminum / steel composite insert, and t is the thickness of the steel stamping. The laser self-fluxing welding seam 7 has a penetration depth of not more than (M - t - 0.5) mm for two reasons. First, to prevent the steel layer 13 of the aluminum / steel composite insert from melting, because even a small amount of melting of the steel layer 13 of the aluminum / steel composite insert into the laser self-fluxing welding seam 7 will seriously deteriorate the weldability of the seam. Second, to prevent the laser welding from affecting the structure and performance of the non-tongue flange area on the flange 2 of the aluminum stamping. In this invention, the area affected by welding and the laser self-fluxing welding seam 7 with weaker performance are both located on the tongue flange 3 of the flange 2 of the aluminum stamping, but at this time the load-bearing area becomes the welded joint formed by the tongue flange 3 and the aluminum layer 14 of the aluminum / steel composite insert, and the thickness of the load-bearing area is much larger than the thickness of the aluminum stamping 1, so after the combined process of "preparing the tongue flange + inserting the aluminum / steel composite insert + laser self-fluxing welding", the load-bearing performance of the flange 2 of the aluminum stamping is not only not weakened, but is actually strengthened.

[0053] Step 6: Process a plurality of blind holes in the aluminum layer of the aluminum / steel composite insert, and the depth of the blind holes is equal to the difference between the thickness of the aluminum / steel composite insert and the thickness of the steel layer thereof, as shown in Figure 8 .

[0054] If the blind hole 15 is not processed, the subsequent resistance spot welding becomes the welding between the aluminum / steel composite plate insert 5 and the steel stamping 6, which is almost impossible to obtain effective welding strength. If the blind hole 15 is processed in the aluminum layer 14 of the aluminum / steel composite plate insert and the hole depth of the blind hole 15 is equal to the difference between the thickness of the aluminum / steel composite plate insert 5 and the thickness of the steel layer thereof, the purpose is to remove the aluminum layer of the aluminum / steel composite plate insert at the welding position completely, leaving only the steel layer 13 of the aluminum / steel composite plate insert, and when the subsequent resistance spot welding is performed, one electrode presses the flange 11 of the steel stamping, and the other electrode extends into the blind hole 15 and presses the steel layer 13 of the aluminum / steel composite plate insert, so that the resistance spot welding between the aluminum / steel composite plate insert 5 and the steel stamping 6 becomes the resistance spot welding between the steel plate and the steel plate, and the material and thickness of the two welded steel plates are consistent, so that excellent spot welding quality can be obtained under the mature and simple welding process.

[0055] The opening size of the blind hole 15 is important, and under the premise of ensuring that the spot welding electrode can easily extend into the blind hole 15 for welding, the blind hole 15 should be as small as possible. The electrode size is determined by the size of the welding nugget 16 of the welding spot, and the size of the welding nugget 16 depends on the thickness of the welded plate, so the thickness of the sheet material of the steel stamping 6 determines the minimum diameter of the blind hole 15. However, unlike the resistance spot welding between two simple steel plates, the aluminum / steel composite plate 8 and the connected aluminum stamping 1 have fast heat dissipation, and under the same conditions, the welding nugget 16 of the spot welding becomes smaller, so the electrode diameter needs to be appropriately increased to expand the welding nugget 16 of the spot welding, and the blind hole 15 should also be correspondingly increased. The present application finds that when the relationship between the minimum diameter of the blind hole 15 and the thickness of the sheet material of the steel stamping 6 is (4 +3.5) mm (t is the thickness of the sheet material of the steel stamping 6), the minimum diameter of the blind hole 15 can not only ensure the easy extension and exit of the electrode during welding, but also obtain the welding nugget 16 size that meets the welding strength requirement.

[0056] The smaller the distance between the blind holes 15 is, the higher the connection strength between the aluminum stamping 1 and the steel stamping 6 is, and the smaller the gap between the two stampings after welding is, but too small distance will inevitably increase the influence of the shunt during welding, and also reduce the aluminum-steel bonding interface area of the aluminum / steel composite plate insert 5. At the same time, unlike the resistance spot welding between two simple steel plates, the aluminum / steel composite plate 8 is thick and the aluminum layer has strong conductivity, so the shunt problem is more obvious during spot welding. The present application finds that when the distance between the blind holes 15 of the aluminum / steel composite plate insert 5 is greater than or equal to 22 (t is the thickness of the sheet material of the steel stamping 6), the welding shunt problem can be ensured to be not obvious, and the number of blind holes 15 can be ensured not to affect the carrying capacity of the aluminum / steel composite plate insert 5.

[0057] The bottom surface of the blind hole is a flat surface, and the roughness is not higher than Ra 1.6 μm.

[0058] Step 7: preparing the steel stamping.

[0059] The steel stamping part 6 is prepared by using punching, deep drawing, bending and other sheet forming methods.

[0060] Step 8: The steel layers of the aluminum / steel composite plate inserts corresponding to the bottom surfaces of the blind holes and the overlapping edges of the steel stamping part are welded by using resistance spot welding to prepare a steel-aluminum composite stamping and welding structure, as shown in Figure 9 .

[0061] The steel layers 13 of the aluminum / steel composite plate inserts corresponding to the bottom surfaces of the blind holes 15 and the overlapping edges 11 of the steel stamping part are welded by using appropriate resistance spot welding process parameters.

[0062] Step 9: Fill the structure glue in the blind holes, as shown in Figure 10 .

[0063] After the aluminum stamping part 1 and the steel stamping part 6 are resistance spot welded, the structure glue 17 is filled in the blind hole 15, which can further strengthen the load-carrying capacity of the aluminum / steel composite plate insert 5 during service, and can prevent the corrosion problem caused by water accumulation in the blind hole 15 during service.

[0064] Example 2

[0065] The sheet material and thickness of the steel stamping part, the aluminum stamping part and the aluminum / steel composite plate of this example are as follows: (1) the sheet thickness of the steel stamping part is 1.2 mm, and the material is dual-phase high-strength steel DP590; (2) the sheet thickness of the aluminum stamping part is 2 mm, and the material is AA6016.

[0066] The manufacturing method of the steel-aluminum composite stamping and welding structure of this example includes the following steps:

[0067] Step 1: Prepare an AA6016 stamping part;

[0068] The AA6016 stamping part is prepared by using deep drawing method, and the overlapping edge thickness is equal to the sheet thickness of the aluminum stamping part, which is 2 mm, the overlapping edge width of the aluminum stamping part is 25 mm, and the overlapping edge length required to be connected with the steel stamping part is 300 mm.

[0069] Step 2: Form the tab flange and tab flange hole on the overlapping edge of the aluminum stamping part;

[0070] The tab flange and tab flange hole are formed on the overlapping edge of the aluminum stamping part by using the methods of hole opening, cutting release groove and bending. That is, a rectangular hole with a length of 280 mm and a width of 5 mm is first opened in the middle of the overlapping edge of the aluminum stamping part, then 45° release grooves are cut at the four corners of the rectangular hole, and finally the four tabs are all outwardly folded and bent by 90° to prepare a tab flange with a height of 7 mm and a tab flange hole with a length of 280 mm and a width of 15 mm. The height of the tab flange satisfies the requirement of the minimum value 3×2+1=7 mm.

[0071] Step 3: Cut the aluminum / steel clad plate with a thickness equal to the height of the tongue flange to prepare the aluminum / steel clad plate insert according to the shape of the tongue flange hole;

[0072] An aluminum / steel clad plate with a thickness equal to 7 mm plus the height of the tongue flange is selected as the raw material, and the aluminum / steel clad plate insert with a length of 280 mm, a width of 15 mm, and a thickness of 7 mm is prepared by cutting according to the shape of the rectangular tongue flange hole with a length of 280 mm and a width of 15 mm. The cutting method is preferably electric discharge wire cutting. The cutting precision should ensure that the single-side gap between the aluminum / steel clad plate insert and the tongue flange is less than or equal to 30 μm.

[0073] The aluminum / steel clad plate is prepared by explosive welding. The steel layer is 1.2 mm thick and made of DP590. The aluminum layer is 5.8 mm thick and made of AA6016 with a thickness of 4.8 mm and AA1060 with a thickness of 1 mm. AA1060 is located between AA6016 and DP590 and acts as an intermediate layer.

[0074] Step 4: Embed the aluminum / steel clad plate insert into the tongue flange hole, and the steel side surface of the aluminum / steel clad plate insert is flush with the overlapping edge surface of the aluminum stamping part;

[0075] Embed the aluminum / steel clad plate insert into the tongue flange hole on the overlapping edge of the aluminum stamping part, so that the steel side surface of the aluminum / steel clad plate insert is flush with the overlapping edge surface of the aluminum stamping part.

[0076] Step 5: Weld the aluminum layer of the aluminum / steel clad plate insert to the tongue flange by laser self-fusion welding;

[0077] Laser self-fusion welding is used to complete the welding between the aluminum layer of the aluminum / steel clad plate insert and the tongue flange. The weld penetration of laser self-fusion welding should be not greater than M - t - 0.5 = 7 - 1.2 - 0.5 = 5.3 mm. Considering the volatility of the weld penetration, the weld penetration is selected to be 4.8 mm.

[0078] Step 6: Process a plurality of blind holes on the aluminum side of the aluminum / steel clad plate insert, and the blind hole depth is equal to the difference between the thickness of the aluminum / steel clad plate insert and the thickness of the steel layer thereof;

[0079] The minimum diameter of the blind hole is required to be 4 + 3.5 = 4 + 3.5 = 7.9 mm, and the diameter of the blind hole in this example is 8 mm. The minimum spacing of each blind hole is required to be 22 = 22 = 24 mm, and the spacing of each blind hole in this example is 25 mm.

[0080] Step 7: Prepare a steel stamping part;

[0081] The steel stamping part is prepared by a bending forming method.

[0082] Step 8: The steel layers of the aluminum / steel composite plate inserts corresponding to the bottom surfaces of the blind holes and the lap joints of the steel stamping part are welded by resistance spot welding to form a steel-aluminum composite stamping and welding structure.

[0083] The steel layers of the aluminum / steel composite plate inserts corresponding to the bottom surfaces of the blind holes and the lap joints of the steel stamping part are welded by resistance spot welding by using appropriate resistance spot welding process parameters and an electrode with a 6 mm end face diameter.

[0084] Step 9: The blind holes are filled with structural adhesive.

[0085] After the aluminum stamping part and the steel stamping part are welded by resistance spot welding, the blind holes are filled with structural adhesive.

[0086] Connection performance detection:

[0087] The aluminum stamping part is replaced by an aluminum flat plate with a length of 300 mm, a width of 100 mm and a thickness of 2 mm, and the steel stamping part is replaced by a steel flat plate with a length of 300 mm, a width of 100 mm and a thickness of 1.2 mm, and other conditions are the same as the corresponding conditions of the present example. The aluminum flat plate and the steel flat plate are welded by using the same steps and parameters as in the present example (the lap joint is along the length direction of the flat plate, and the lap joint width is 25 mm) to form an aluminum flat plate-steel flat plate welding test sample. After welding, 5 single-welded point tensile shear samples and 3 single-welded point metallographic detection samples are cut from the aluminum flat plate-steel flat plate welding test sample, the shear sample size is 160 mm long by 25 mm wide, and the lap joint is in the middle of the shear sample.

[0088] The metallographic sample detection shows that the weld nugget diameter is between 5.7-6.0 mm, the weld nugget structure is dense and free of welding defects. The sample tensile shear test shows that the tensile shear force is between 12.56-13.17 KN, and the weld fracture mode is the weld nugget pull-out fracture. The metallographic analysis of the tensile shear fractured sample shows that the steel / aluminum interface of the aluminum / steel composite plate insert has no cracking marks. The results of metallographic analysis, tensile shear and post-tensile shear analysis show that the welding quality of the aluminum stamping part and the steel stamping part welded by the method of the present application reaches the welding quality level of the same material steel stamping part and steel stamping part.

[0089] Example 3

[0090] The plate material and thickness of the steel stamping part, the aluminum stamping part and the aluminum / steel composite plate of the present example are as follows: (1) the steel stamping part plate material is 1.2 mm thick and the material is low carbon steel DC01; (2) the aluminum stamping part plate material is 1.5 mm thick and the material is AA5182.

[0091] The manufacturing method of the steel-aluminum composite stamping and welding structure of the present example comprises the following steps:

[0092] Step 1: preparing AA5182 stamping part;

[0093] AA5182 stamping part is prepared by drawing method, the overlap thickness is equal to the thickness of aluminum stamping part sheet 1.5 mm, the overlap width is 25 mm, and the overlap length required to be connected with steel stamping part is 300 mm.

[0094] Step 2: forming tab flange and tab flange hole on the overlap of aluminum stamping part;

[0095] Tab flange and tab flange hole are formed on the overlap of aluminum stamping part by means of hole opening, cutting release groove and bending. That is, a rectangular hole with a length of 280 mm and a width of 5 mm is first opened in the middle of the overlap of aluminum stamping part, then 45° release grooves are cut at the four corners of the rectangular hole, and finally the four tabs are turned out and bent 90° to prepare tab flange with a height of 6 mm and tab flange hole with a length of 280 mm and a width of 15 mm. The height of the tab flange meets the requirement of the minimum value 3x1.5+1=5.5 mm.

[0096] Step 3: cutting aluminum / steel composite plate insert from aluminum / steel composite plate with thickness equal to the height of tab flange according to the shape of tab flange hole;

[0097] Aluminum / steel composite plate with thickness equal to the height of tab flange 6 mm is selected as raw material, and aluminum / steel composite plate insert with a length of 280 mm, a width of 15 mm and a thickness of 6 mm is prepared by cutting according to the shape of rectangular tab flange hole with a length of 280 mm and a width of 15 mm. The cutting processing method is preferably electric spark wire cutting method. The cutting processing precision should ensure that the single-sided gap between the aluminum / steel composite plate insert and the tab flange is less than or equal to 30 μm.

[0098] The aluminum / steel composite plate is prepared by explosive welding, the steel layer is 1.2 mm thick and the material is DC01; the aluminum layer is 4.8 mm thick, and the aluminum layer material is composed of AA5182 with a thickness of 3.8 mm and AA1060 with a thickness of 1 mm, wherein AA1060 is located between AA5182 and DC01 and acts as an intermediate layer.

[0099] Step 4: embedding the aluminum / steel composite plate insert into the tab flange hole, and the steel side surface of the aluminum / steel composite plate insert is flush with the surface of the aluminum stamping part overlap;

[0100] The aluminum / steel composite plate insert is embedded into the tab flange hole of the aluminum stamping part overlap, so that the steel side surface of the aluminum / steel composite plate insert is flush with the surface of the aluminum stamping part overlap.

[0101] Step 5: welding the aluminum layer of the aluminum / steel composite plate insert and the tab flange by laser self-fluxing welding;

[0102] The laser self-fusion welding is used to complete the welding between the aluminum layer of the aluminum / steel composite plate insert and the tab flange. The weld penetration of the laser self-fusion welding should be not greater than M-t-0.5=6-1.2-0.5=4.3mm, and considering the fluctuation of the weld penetration, the weld penetration is selected as 4.0mm.

[0103] Step 6: A plurality of blind holes are processed on the aluminum side of the aluminum / steel composite plate insert, and the blind hole depth is equal to the difference between the thickness of the aluminum / steel composite plate insert and the thickness of the steel layer thereof;

[0104] The minimum diameter requirement of the blind hole is 4 +3.5=4 +3.5=7.9mm, and the blind hole diameter is selected as 8mm in the example. The minimum spacing requirement of each blind hole is 22 =22 =24mm, and the spacing of each blind hole is selected as 28mm in the example.

[0105] Step 7: The steel stamping part is prepared;

[0106] The steel stamping part is prepared by the bending forming method.

[0107] Step 8: The lap joints between the steel layer of the aluminum / steel composite plate insert corresponding to the bottom surface of each blind hole and the steel stamping part are welded by resistance spot welding to form a steel-aluminum composite stamping and welding structure;

[0108] The lap joints between the steel layer of the aluminum / steel composite plate insert corresponding to the bottom surface of each blind hole and the steel stamping part are welded by resistance spot welding by using appropriate resistance spot welding process parameters and an electrode with an end face diameter of 6mm.

[0109] Step 9: The structure glue is filled in each blind hole.

[0110] After the resistance spot welding between the aluminum stamping part and the steel stamping part is completed, the structure glue is filled in the blind hole.

[0111] Connection performance detection:

[0112] The aluminum stamping part is replaced by an aluminum flat plate with a length of 300mm, a width of 100mm and a thickness of 1.5mm, the steel stamping part is replaced by a steel flat plate with a length of 300mm, a width of 100mm and a thickness of 1.2mm, and the material and other conditions are the same as the corresponding conditions of the example. The aluminum flat plate and the steel flat plate are overlapped and welded (overlapped along the length direction of the flat plate, and the overlap width is 25mm) by using the same steps and parameters as the example to form an aluminum flat plate-steel flat plate welding test sample. After welding, 5 single weld point tensile shear samples and 3 single weld point metallographic detection samples are cut from the aluminum flat plate-steel flat plate welding test sample, the shear sample size is 160mm in length, 25mm in width, and the overlap weld point is located in the middle of the shear sample.

[0113] Metallographic sample detection shows that the welding core diameter is between 5.7-5.9mm, the welding core structure is dense and has no welding defects. The tensile shear test shows that the tensile shear force is between 7.95-8.38KN, and the fracture mode of the welding spot is the fracture of the welding core pulling out. The metallographic analysis of the sample after the tensile shear fracture shows that the steel / aluminum interface of the aluminum / steel composite plate insert has no cracking trace. The results of the metallographic analysis, the tensile shear test and the analysis after the tensile shear test show that the welding quality of the aluminum stamping part and the steel stamping part welded by the method of the present application reaches the welding quality level of the steel stamping parts welded with the same material.

[0114] Example 4

[0115] The plate material and thickness of the steel stamping part, the aluminum stamping part and the aluminum / steel composite plate of the present example are as follows: (1) the thickness of the steel stamping part is 1.0mm, and the material is low-carbon steel DC05; (2) the thickness of the aluminum stamping part is 1.0mm, and the material is AA6016.

[0116] The manufacturing method of the steel-aluminum composite stamping and welding structure of the present example comprises the following steps:

[0117] Step 1: preparing the AA6016 stamping part;

[0118] The AA6016 stamping part is prepared by the deep drawing method, the thickness of the aluminum stamping part is 1mm, the width of the flange is 25mm, and the length of the flange to be connected with the steel stamping part is 300mm.

[0119] Step 2: opening a hole and cutting a release groove on the flange of the aluminum stamping part and bending to form the tab flange and the tab flange hole;

[0120] The tab flange and the tab flange hole are formed on the flange of the aluminum stamping part by the method of opening a hole, cutting a release groove and bending. That is, a rectangular hole with a length of 280mm and a width of 5mm is first opened in the middle of the flange of the aluminum stamping part, then 45° release grooves are cut at the four corners of the rectangular hole, and finally the four tabs are folded and bent outwards by 90° to prepare a tab flange with a height of 4mm and a tab flange hole with a length of 280mm and a width of 15mm. The height of the tab flange meets the requirement of the minimum value of 3x1.0+1=4mm.

[0121] Step 3: cutting the aluminum / steel composite plate insert according to the shape of the tab flange hole with the aluminum / steel composite plate with a thickness equal to the height of the tab flange as the raw material;

[0122] The aluminum / steel composite plate with a thickness equal to the height of the tab flange of 4mm is selected as the raw material, and the aluminum / steel composite plate insert with a length of 280mm, a width of 15mm and a thickness of 4mm is prepared by cutting according to the shape of the rectangular tab flange hole with a length of 280mm and a width of 15mm. The cutting processing method is preferably electric spark wire cutting method. The cutting processing precision should ensure that the single-side gap between the aluminum / steel composite plate insert and the tab flange is less than or equal to 30μm.

[0123] The aluminum / steel composite plate is prepared by explosion welding, the steel layer has a thickness of 1.0 mm and is made of DC05; the aluminum layer has a thickness of 3 mm and is made of AA6016 with a thickness of 2.4 mm and AA1060 with a thickness of 0.6 mm, wherein the AA1060 is located between the AA6016 and the DC05 and acts as an intermediate layer.

[0124] Step 4: embedding the aluminum / steel composite plate insert into the tongue flange hole, the steel side surface of the aluminum / steel composite plate insert is flush with the aluminum stamping part lap surface;

[0125] embedding the aluminum / steel composite plate insert into the tongue flange hole on the lap of the aluminum stamping part, so that the steel side surface of the aluminum / steel composite plate insert is flush with the aluminum stamping part lap surface.

[0126] Step 5: welding the aluminum layer of the aluminum / steel composite plate insert and the tongue flange by laser self-fusion welding;

[0127] The welding between the aluminum layer of the aluminum / steel composite plate insert and the tongue flange is completed by laser self-fusion welding. The weld penetration of the laser self-fusion welding should be not greater than M-t-0.5=4-1.0-0.5=2.5 mm, and considering the fluctuation of the weld penetration, the weld penetration is selected to be 2.3 mm.

[0128] Step 6: processing a plurality of blind holes on the aluminum side of the aluminum / steel composite plate insert, the blind hole depth is equal to the difference between the thickness of the aluminum / steel composite plate insert and the thickness of the steel layer thereof;

[0129] The minimum diameter of the blind hole is required to be 4 +3.5=4 +3.5=7.5 mm, and the diameter of the blind hole in the example is selected to be 7.5 mm. The minimum spacing of each blind hole is required to be 22 =22 =22 mm, and the spacing of each blind hole in the example is selected to be 22 mm.

[0130] Step 7: preparing a steel stamping part;

[0131] The steel stamping part is prepared by bending forming.

[0132] Step 8: welding the lap of the steel layer of the aluminum / steel composite plate insert and the steel stamping part corresponding to the bottom surface of each blind hole by resistance spot welding to prepare a steel-aluminum composite stamping and welding structure;

[0133] The resistance spot welding between the lap of the steel layer of the aluminum / steel composite plate insert and the steel stamping part corresponding to the bottom surface of each blind hole is completed by using appropriate resistance spot welding process parameters and an electrode with an end face diameter of 5.5 mm.

[0134] Step 9: filling the structure adhesive into each blind hole.

[0135] After the aluminum stamping piece and the steel stamping piece are resistance spot welded, the blind hole is filled with structural adhesive.

[0136] Connection performance detection:

[0137] The aluminum stamping piece is replaced by an aluminum flat plate with a length of 300 mm, a width of 100 mm, and a thickness of 1.0 mm, and the steel stamping piece is replaced by a steel flat plate with a length of 300 mm, a width of 100 mm, and a thickness of 1.0 mm, and other conditions are the same as the corresponding conditions of the present example. An aluminum flat plate and a steel flat plate are lap welded (lap along the length direction of the flat plate, and the lap width is 25 mm) by using the same steps and parameters as in the present example to obtain an aluminum flat plate-steel flat plate welded test sample. After welding, five single-welded point tensile shear samples and three single-welded point metallographic detection samples are cut from the aluminum flat plate-steel flat plate welded test sample, the shear sample size is 160 mm in length and 25 mm in width, and the lap welded point is located in the middle of the shear sample.

[0138] The metallographic sample detection shows that the weld nugget diameter is between 5.4-5.6 mm, the weld nugget structure is dense, and there is no welding defect. The tensile shear test of the sample shows that the tensile shear force is between 5.42-5.72 KN, and the fracture mode of the welded point is the pull-out fracture of the weld nugget. The metallographic analysis of the tensile shear fractured sample shows that there is no cracking trace on the steel / aluminum interface of the aluminum / steel composite plate insert. The results of metallographic analysis, tensile shear, and analysis after tensile shear show that the welding quality of the aluminum stamping piece and the steel stamping piece welded by the method of the present application reaches the welding quality level of the steel stamping piece welded with the same material steel stamping piece.

Claims

1. A method of manufacturing a steel-aluminum composite press-weld structure, characterized by, The method comprises the following steps: Step 1: preparing an aluminum stamping part; Step 2: forming a tab flange and a tab flange hole on the flange of the aluminum stamping part; Step 3: cutting an aluminum / steel composite plate insert from an aluminum / steel composite plate with a thickness equal to the height of the tab flange according to the shape of the tab flange hole; Step 4: embedding the aluminum / steel composite plate insert into the tab flange hole, and the surface of the steel layer of the aluminum / steel composite plate insert is flush with the surface of the flange of the aluminum stamping part; Step 5: welding the aluminum layer of the aluminum / steel composite plate insert to the tab flange; Step 6: processing a plurality of blind holes in the aluminum layer of the aluminum / steel composite plate insert, and the depth of the blind holes is equal to the difference between the thickness of the aluminum / steel composite plate insert and the thickness of the steel layer of the aluminum / steel composite plate insert; Step 7: preparing a steel stamping part; Step 8: welding the steel layer of the aluminum / steel composite plate insert corresponding to the bottom surface of each blind hole to the flange of the steel stamping part to form a steel-aluminum composite stamping and welding structure; Step 9: filling the structure adhesive into each blind hole.

2. The method of manufacturing a steel-aluminum composite drawn and welded structure according to claim 1, characterized in that, The step 2 specifically comprises the following steps: first, opening a rectangular hole in the middle of the flange of the aluminum stamping part, cutting 45° release grooves at four corners of the rectangular hole, and finally folding and bending the tab outward by 90° to form the tab flange and the tab flange hole.

3. The method of manufacturing a steel-aluminum composite drawn and welded structure according to claim 1 or 2, characterized in that, The height of the tab flange is not less than (3n+1) mm, wherein n=max (the thickness of the steel stamping part, the thickness of the aluminum stamping part).

4. The method of manufacturing a steel-aluminum composite drawn and welded structure according to claim 1, characterized in that, The material and thickness of the steel layer of the aluminum / steel composite plate are consistent with those of the steel stamping part.

5. The method of manufacturing a steel-aluminum composite drawn and welded structure according to claim 1, characterized in that, The single-sided gap between the aluminum / steel composite plate insert and the tab flange is less than or equal to 30 μm.

6. The method of manufacturing a steel-aluminum composite punch-welded structure according to claim 1, characterized by, The aluminum layer of the aluminum / steel composite plate insert and the tab flange are welded by laser self-fluxing welding, and the penetration depth of the laser self-fluxing welding seam is not greater than (M-t-0.5) mm, wherein M is the thickness of the aluminum / steel composite plate insert, and t is the thickness of the steel stamping part.

7. The method of manufacturing a steel-aluminum composite punch-welded structure according to claim 1, characterized by, The minimum diameter of the blind hole is: (4 + 3.5) mm, where t is the sheet thickness of the steel stamping.

8. The method of manufacturing a steel-aluminum composite punch-welded structure according to claim 1, characterized by, The pitch of the blind holes is greater than or equal to 22 t is the thickness of the sheet metal of the steel stamping.

9. The method of manufacturing a steel-aluminum composite punch-weld structure according to claim 1, characterized by, The welding method used in the step 8 is resistance spot welding.

10. The method of manufacturing a steel-aluminum composite punch-weld structure according to claim 9, characterized by, When the resistance spot welding is used, one electrode presses the flange of the steel stamping part, and the other electrode extends into the blind hole and presses the steel layer of the aluminum / steel composite plate insert.

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