A method of welding an aluminium steel joint for electrolytic aluminium

Abstract

This invention relates to a welding method for aluminum-steel connecting layers in electrolytic aluminum production, comprising the following steps: Step 1: Fixing the steel parts to be welded using a fixing fixture and pressure block, and then pre-treating the connecting surfaces of the steel parts; Step 2: Determining the effective welding area on the connecting surfaces of the steel parts; Step 3: Determining the effective path area A2 on the connecting surfaces of the steel parts; Step 4: Determining the welding process; Step 5: Determining the welding path shape according to the welding process, then planning the welding path and completing the welding. When using friction stir welding, a U-shaped path is selected; when using additive manufacturing, a reciprocating U-shaped path is selected. The equipment control system generates a simulated welding path based on the effective path area A2, the welding path shape, the starting point of the welding path, and the Y-axis path spacing L of each pass in the welding path. This invention replaces brazing with friction stir welding or additive manufacturing, greatly simplifying the process and improving the automation level of the equipment, while ensuring welding quality.

Description

Technical Field

[0001] This invention relates to the field of electrolytic aluminum technology, and more specifically to a welding method for aluminum-steel connecting layers in electrolytic aluminum. Background Technology

[0002] As the core equipment in aluminum electrolysis production, the structural lifespan and performance of conductive components of aluminum electrolysis cells directly affect the output and overall energy consumption of aluminum electrolysis enterprises. Among them, the connection process and connection quality of key conductive connection components such as aluminum guide rods and steel claw assemblies, cathode steel rods and aluminum flexible strip assemblies are important factors affecting the energy efficiency of electrolysis cells, and are also one of the technical directions that urgently need to be optimized under the current dual control of energy consumption.

[0003] Currently, the mainstream connection processes for aluminum guide rods and steel claws are mainly divided into two types: one is to use an explosive welding composite transition block (aluminum-steel composite interface) as an intermediate connector, which is then circumferentially welded to both the steel claw and the aluminum guide rod; the other is to use an aluminum-steel brazing process, where an aluminum layer is first deposited on the surface of the steel claw, and then circumferentially welded to the aluminum guide rod. The connection between the cathode steel rod and the aluminum flexible strip is mainly divided into two types: pressing and welding. The welding method can be further subdivided into: first, connecting the cathode steel rod and the steel connecting piece through "steel-steel" welding, then welding the steel connecting piece to the steel side of the explosive welding transition block, and finally performing "aluminum-aluminum" welding between the aluminum side of the transition block and the aluminum flexible strip; second, directly welding the cathode steel rod to the aluminum flexible strip after depositing an aluminum layer on its surface.

[0004] Existing technologies primarily focus on materials to ensure reliable welding of different metals like aluminum and steel. For example, patent CN116786950B discloses a method for directly connecting an aluminum anode guide rod to a steel claw, which modifies the surface of the steel claw by spraying a mixed powder of specific components onto it to ensure a connection. Another example is patent CN108723534B, which discloses a method for electrolytic aluminum cathode steel-aluminum brazing, which uses a flux of specific components uniformly coated on the surface of the workpiece to ensure a connection. However, both of these patents involve brazing, which typically uses welding wire and usually requires multiple layers and passes to form the aluminum layer. The process is relatively complex and easily affected by environmental factors and operator skill. Summary of the Invention

[0005] The purpose of this invention is to provide a welding method for aluminum-steel connecting layers in electrolytic aluminum, which uses friction stir welding or additive manufacturing to replace brazing, greatly simplifying the process and improving the automation level of the equipment, while ensuring welding quality.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for welding an aluminum-steel connecting layer for electrolytic aluminum includes the following steps:

[0008] Step 1: Fix the steel parts to be welded using the fixing tooling blocks, and then pre-treat the connection surfaces of the steel parts;

[0009] Step 2: Determine the effective welding area A1 on the steel component connection surface according to the following formula (1):

[0010] A1=X1×Y1

[0011] X1=W-2D

[0012] Y1=H-2D (1);

[0013] In the above formula (1), W is the length of the steel connection surface, H is the width of the steel connection surface, and D is the amount of pressure of the fixed tooling pressure block on the steel connection surface;

[0014] Step 3: Determine the effective path area A2 on the steel component connection surface according to the following formula (2):

[0015] A2 = X2 × Y2

[0016] X2 = X1 - 2S - d

[0017] Y2 = Y1 - 2S - d (2);

[0018] In the above formula (2), S is the safety margin distance between the welding head and the fixed tooling block, and d is the diameter of the welding head;

[0019] Step 4: Determine the welding process, which includes friction stir welding, additive manufacturing, or a combination of friction stir welding and additive manufacturing.

[0020] Step 5: Determine the welding path shape according to the welding process, then plan the welding path and complete the welding, specifically as follows:

[0021] Step 5.1: Determine the shape of the welding path. When using friction stir welding, the welding path shape is selected as a U-shaped path, and the starting point of the welding path is the center point O1 of the effective path area A2. When using additive manufacturing, the welding path shape is selected as a reciprocating U-shaped path, and the starting point of the welding path is any corner O2 of the effective path area A2.

[0022] Step 5.2: Set the distance L between each Y-axis path of the welding path, and the equipment control system generates a simulated welding path based on the effective path area A2 determined in Step 3, the welding path shape and welding path starting point determined in Step 5.1, and the distance L.

[0023] Step 5.3: Set the welding process parameters of the welding equipment, and then start the welding equipment to make the welding head move according to the simulated welding path generated in step 5.2 to complete the welding.

[0024] In step 5, when the welding path shape in step 5.1 is selected as a U-shaped path, the U-shaped path includes a Y-direction path and an X-direction path. In step 5.2, the spacing between each Y-direction path is set to L, and the U-shaped path is determined according to the following formula (3).

[0025] X2 / L=n

[0026] Y2 / n=L' (3;

[0027] In the above formula (3), n is the number of path interval segments, and L' is the distance between each X-direction path.

[0028] In step five, when the welding path shape in step 5.1 is selected as a reciprocating U-shaped path, in step 5.2 the spacing between each Y-direction path is set to L, and the number of interval segments n' forming the reciprocating U-shaped path is determined according to the following formula (4):

[0029] n'=X2 / L (4;

[0030] At the same time, all Y-axis paths have the same length and are all Y2.

[0031] When the welding process in step four adopts the single-layer friction stir welding process, the single-layer aluminum alloy plate used as the welding material in step 5.1 is placed on the connecting surface of the steel part, and each side is pressed and fixed by the fixing tooling block. The area of ​​the single-layer aluminum alloy plate and the connecting surface of the steel part are equal, and the welding path shape is selected as a U-shaped path. The welding process parameters of the welding equipment in step 5.3 include a welding head angle of 2°, a welding pressure of 35~50KN, a rotation speed of 800~1000rpm, and a welding speed of 150~200mm / min.

[0032] When the welding process in step four uses a double-layer friction stir welding process, step five specifically involves:

[0033] Step 5.1: Determine that the welding paths for both the lower and upper aluminum alloy plates are zigzag paths;

[0034] Step 5.2: Set the distance La between each Y-axis path of the lower aluminum alloy plate and generate the first simulated welding path; set the distance Lb between each Y-axis path of the upper aluminum alloy plate and generate the second simulated welding path.

[0035] Step 5.3: Place the lower aluminum alloy plate on the steel part connection surface, and fix each side by pressing it down with a fixing tooling block. Set the welding process parameters of the welding equipment, and then start the welding equipment to make the welding head move according to the first simulated welding path generated in step 5.2 to complete the welding.

[0036] Then, the upper aluminum alloy plate is placed on the lower aluminum alloy plate, and each side is pressed and fixed by the fixing tooling blocks. The welding process parameters of the welding equipment are set, and then the welding equipment is started to make the welding head move according to the second simulated welding path generated in step 5.2 to complete the welding.

[0037] The welding process parameters for the welding equipment during the two welding operations are set as follows: welding head angle 1°, welding pressure 29~37KN, rotation speed 300~600rpm, and welding speed 180~300mm / min.

[0038] The areas of the lower aluminum alloy plate, the upper aluminum alloy plate, and the connecting surface of the steel component are equal.

[0039] In step 5.3, after the lower aluminum alloy plate is welded, its upper surface is first milled, and then the upper aluminum alloy plate is placed on the lower aluminum alloy plate.

[0040] When additive manufacturing is used in step four, the welding material used in step 5.1 is one of aluminum alloy rod, aluminum alloy powder or aluminum alloy wire, and the additive manufacturing process is one of continuous rod feeding additive manufacturing, continuous powder feeding additive manufacturing or connecting wire feeding additive manufacturing; the welding process parameters of the welding equipment in step 5.3 include welding head angle 0°, welding pressure 35~50KN, rotation speed 800~1000rpm, and welding speed 150~200mm / min.

[0041] When step four employs a combination of friction stir welding and additive manufacturing, step five specifically involves:

[0042] Step 5.1: Determine that the solder for friction stir welding is a single-layer aluminum alloy plate and the welding path is a U-shaped path; determine that the solder for additive manufacturing is an aluminum alloy rod and the welding path is a reciprocating U-shaped path.

[0043] Step 5.2: Set the distance Lc between each Y-axis path of friction stir welding and generate a simulated U-shaped welding path; set the distance Ld between each Y-axis path of additive manufacturing and generate a simulated reciprocating U-shaped welding path.

[0044] Step 5.3: Place a single-layer aluminum alloy plate on the connecting surface of the steel part, and fix each side by pressing and fixing it with a fixing tooling block. Set the stirring friction welding process parameters of the welding equipment, including welding head angle 2°, welding pressure 35~50KN, rotation speed 800~1000rpm, and welding speed 150~200mm / min.

[0045] Then the welding equipment is started, causing the welding head to move along the simulated U-shaped welding path generated in step 5.2 to complete the welding;

[0046] Then set the additive manufacturing welding process parameters of the welding equipment, including welding head angle 0°, welding pressure 35~50KN, rotation speed 800~1000rpm, welding speed 150~200mm / min, start the welding equipment and move according to the simulated reciprocating U-shaped welding path generated in step 5.2 to complete the welding;

[0047] In step one, the pretreatment of the steel component connection surface includes flatness and cleanliness pretreatment as well as modification pretreatment.

[0048] The advantages and positive effects of this invention are as follows:

[0049] 1. Compared with the prior art, the present invention can not only replace the aluminum-steel transition block process, but also replace the process of forming an aluminum layer by multi-layer and multi-pass welding by one-time friction stir welding or additive manufacturing. The process is greatly simplified and the level of equipment automation is improved.

[0050] 2. In the welding path planning, the present invention selects a zigzag path and a reciprocating U-shaped path according to the welding process. These two paths can ensure the welding path density on the one hand, and on the other hand, ensure that the welding path covers the effective path area A2 as much as possible. This allows processes such as friction stir welding or additive manufacturing to replace existing processes such as brazing. In addition, these two paths are also convenient for adjusting and calculating the simulated welding path. The operator only needs to input the spacing L of each Y-axis path, and the equipment control system can automatically calculate and generate a new simulated welding path.

[0051] 3. The effective welding area A1 and effective path area A2 of the present invention are automatically calculated based on the length and width dimensions of the steel connection surface. At the same time, when planning the welding path, the relevant dimensions of the simulated welding path are also automatically calculated based on the effective path area A2 and the spacing L of each Y-direction path. Compared with the prior art, which uses devices such as laser scanners, displacement sensors, and contour scanners to detect, then provide feedback and calculate, and then control, the present invention eliminates the detection and feedback process, thereby improving the calculation speed of the equipment control system and enabling the rapid acquisition of the simulated welding path generated on the display screen.

[0052] 4. This invention can be used to connect anode steel claws to aluminum rods, as well as cathode steel rods to aluminum flexible strips. Since the simulated welding path is automatically calculated based on the length and width of the steel connection surface, it is also applicable to the connection of anode steel claws to aluminum rods or cathode steel rods to aluminum flexible strips of different specifications (i.e., different areas of steel connection surfaces). Operators only need to adjust the spacing L of each Y-axis path according to the actual situation to automatically generate a suitable simulated welding path. Therefore, this invention has a wide range of applications and is flexible in use.

[0053] 5. The entire welding process of this invention is completed automatically and is not affected by factors such as ambient temperature, humidity, or operator skill, which can ensure welding quality. At the same time, compared with brazing or transition block welding, the welding process of this invention does not require gas protection and generates no welding fumes, which is also beneficial to improving the overall working environment. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the process of the present invention.

[0055] Figure 2 This is a schematic diagram showing the positional relationship between the connection surfaces of a single-layer aluminum alloy plate and a steel component when using friction stir welding in this invention.

[0056] Figure 3 for Figure 2 Schematic diagram of effective welding area and effective path area of ​​single-layer aluminum alloy plate.

[0057] Figure 4 for Figure 3 A schematic diagram showing the fit between the fixed fixture and the welding head and the aluminum alloy plate.

[0058] Figure 5 This is a schematic diagram of the zigzag path used in this invention.

[0059] Figure 6 This is a schematic diagram of the reciprocating U-shaped path used in this invention.

[0060] Figure 7 This is a schematic diagram of the process in the prior art where aluminum guide rods and steel claws are welded together using a transition block process.

[0061] Figure 8 This is a schematic diagram illustrating the process of welding aluminum guide rods and steel claws together using a fusion brazing process in existing technologies.

[0062] Figure 9 This is a schematic diagram of the process in the prior art where a cathode steel rod and an aluminum flexible strip are welded together using a transition block process.

[0063] Figure 10 This is a schematic diagram of the process of welding cathode steel rods and aluminum flexible strips together using a fusion brazing process in the prior art.

[0064] Among them, 1 is an aluminum alloy plate, 2 is a steel connection surface, 3 is a fixing tooling block, and 4 is a welding head. Detailed Implementation

[0065] The invention will now be described in further detail with reference to the accompanying drawings.

[0066] like Figure 1 As shown, the method of the present invention includes the following steps:

[0067] Step 1: Fix the steel parts (steel claws or cathode steel rods) to be welded using the fixing tooling pressure block, and then pre-treat the steel parts connection surface 2.

[0068] In this step, the pretreatment includes mechanical grinding or milling to remove impurities such as oxide scale and oil stains from the steel connection surface 2. The steel connection surface 2 is required to be free of rust, oil stains and other contaminants, thereby ensuring that the flatness and cleanliness of the steel connection surface 2 meet the requirements.

[0069] In addition, in this step, the steel connecting surface 2 can be modified and pretreated with appropriate alloy powder as needed, such as the mixed powder in patent CN116786950B, which is a well-known technology in this field.

[0070] Step Two: As Figures 2-3 As shown, the effective welding area A1 on the steel connection surface 2 is determined according to the following formula (1):

[0071] A1=X1×Y1

[0072] X1=W-2D

[0073] Y1=H-2D (1);

[0074] In the above formula (1), W is the length of the steel connection surface 2, H is the width of the steel connection surface 2, and D is the pressing amount of the fixed tooling pressure block 3 on the steel connection surface 2.

[0075] The fixing fixture is a well-known technology in the field, such as... Figures 3-4 As shown, when the present invention uses an aluminum alloy plate 1 (with the same area as the steel connection surface 2) to perform friction stir welding on the steel connection surface 2, each fixed tooling block 3 presses down on the corresponding side of the aluminum alloy plate 1. However, when the present invention uses an additive manufacturing process, each fixed tooling block 3 directly presses down on each side of the steel connection surface 2.

[0076] Step 3: As Figures 3-4 As shown, the effective path area A2 is determined according to the following formula (2):

[0077] A2 = X2 × Y2

[0078] X2 = X1 - 2S - d

[0079] Y2 = Y1 - 2S - d (2);

[0080] In the above formula (2), such as Figure 4 As shown, S is the safety margin distance between the welding head 4 and the fixed tooling block 3, with a value range of 1 to 5 mm, and d is the diameter of the welding head 4. The subsequent welding path planning of this invention cannot exceed the effective path area A2 range.

[0081] Step 4: Determine the welding process, which includes friction stir welding, additive manufacturing, or a combination of friction stir welding and additive manufacturing.

[0082] Step 5: Determine the welding path shape based on the welding process selected in Step 4, then plan the welding path and complete the welding, specifically as follows:

[0083] Step 5.1: Determine the shape of the welding path, where:

[0084] When the present invention employs friction stir welding, the welding path shape is selected. Figure 5 The path shown is a zigzag shape, and the starting point of the welding path is the center point O1 of the effective path area A2;

[0085] When this invention employs additive manufacturing processes, the selection of the welding path shape... Figure 6 The reciprocating U-shaped path is shown, and the starting point of the welding path is any corner O2 of the effective path area A2;

[0086] One of the design objectives of this invention is to replace the existing multi-layer, multi-pass welding process of friction stir welding or additive manufacturing with the existing brazing process, thereby quickly forming an aluminum alloy connection layer on the steel connection surface 2 for welding to the aluminum part. The zigzag path and the reciprocating U-shaped path can ensure sufficient welding path density, thereby ensuring a reliable connection between the connection layer and the steel connection surface 2, and also facilitating subsequent calculations to adjust the simulated welding path density.

[0087] Step 5.2: Set the distance L between each Y-axis path of the welding path, and the equipment control system generates a simulated welding path based on the effective path area A2 determined in Step 3, the welding path shape and welding path starting point determined in Step 5.1, and the distance L.

[0088] In this step, if using Figure 5 The illustrated zigzag path includes Y-axis paths and X-axis paths, where the spacing between each Y-axis path is L, as shown below. Figure 3 and Figure 5 As shown, the equipment control system determines the zigzag path according to the following formula (3):

[0089] X2 / L=n

[0090] Y2 / n=L' (3;

[0091] In the above formula (3), n is the number of path interval segments, and L' is the distance between each X-direction path.

[0092] by Figure 5For example, X2 / L=n=4, that is, there are four segments L along the X direction. At the same time, in order to ensure that the welding path covers the steel connection surface 2 as much as possible, the present invention sets the number of segments along the Y direction to be the same as n, so Y2 / n=L'.

[0093] In this step, if the following is adopted: Figure 6 The reciprocating U-shaped path shown has a spacing of L between its Y-direction paths. The number of interval segments n' forming the reciprocating U-shaped path is determined according to the following formula (4):

[0094] n'=X2 / L (4;

[0095] by Figure 6 For example, n'=4, meaning it includes four interval segments, and each Y-axis path has the same length, which is Y2. Similarly, to ensure welding density, operators can flexibly adjust L to ensure that the simulated welding path density generated on the display screen meets the requirements.

[0096] To ensure welding density, this invention allows operators to flexibly adjust the distance L, thereby generating simulated welding paths with different path densities. Compared to existing technologies that use laser scanners, displacement sensors, and contour scanners to first detect, then provide feedback and calculate, and finally control, the effective welding area A1 and effective path area A2 of this invention can be automatically calculated by the control system based on the length and width dimensions of the steel connection surface 2. Simultaneously, the relevant dimensions of the simulated welding path are also automatically calculated based on the effective path area A2 and the spacing L of each Y-axis path. This eliminates the detection and feedback processes, thereby improving the calculation speed of the control system and enabling rapid acquisition of the simulated welding path generated on the display screen. Furthermore, the aforementioned displacement sensors can be configured according to actual needs, but are primarily used for verifying the final calculation results to further ensure the accuracy of the path planning.

[0097] Step 5.3: Set the welding process parameters of the welding equipment, and then start the welding equipment to make the welding head 4 move according to the simulated welding path generated in step 5.2 to complete the welding.

[0098] In this step, the welding process parameters of the welding equipment include the angle of the welding head 4, welding pressure, rotation speed, welding speed, etc.

[0099] Finally, after the above-mentioned connecting layer is generated, the present invention welds the aluminum part (aluminum rod or aluminum strip) to the connecting layer to form a complete product. This process is a well-known technology in the field.

[0100] The following examples further illustrate the working process of the present invention.

[0101] Example 1:

[0102] This embodiment employs friction stir welding and performs connection layer welding on the anode steel claw, specifically as follows:

[0103] Step 1: As Figures 2-4 As shown, the steel claw top platform at the upper end of the steel claw to be anode is fixed using a fixing fixture, and then the steel connecting surface 2 at the upper end of the steel claw top platform is pretreated.

[0104] Step 2: Determine the effective welding area A1 on the steel connection surface 2 according to the above formula (1). In this embodiment, the length W=285mm, the width H=245mm, and the clamping amount D=10mm of the fixed tooling of the steel connection surface 2. Therefore, the length X1=285-20=265mm and the width Y1=245-20=225mm of the effective welding area A1.

[0105] Step 3: Determine the effective path area A2 according to the above formula (2). In this embodiment, the safety margin distance S = 2.5mm, the welding head 4 is a welding head with a diameter d = 20mm, and the length of the effective path area A2 is X2 = 265-5-20 = 240mm, Y2 = 225-5-20 = 200mm.

[0106] Step 4: This embodiment uses friction stir welding process, wherein, for example... Figures 2-3 As shown, this embodiment requires the final connection layer thickness to be 12mm. Therefore, this embodiment uses a 13mm thick aluminum alloy plate 1 as the solder for welding. The area of ​​the aluminum alloy plate 1 is equal to that of the steel connection surface 2, which does not affect the above calculation. Each side of the aluminum alloy plate 1 is pressed and fixed on the steel connection surface 2 by the fixing tooling block 3.

[0107] In actual production, the area of ​​the aluminum alloy plate 1 can be larger or smaller than the size of the steel connecting surface 2 according to actual needs, but the difference needs to be strictly controlled. If the size of the aluminum alloy plate 1 is much smaller than the size of the steel connecting surface 2, the pressing amount D of the special fixing fixture will increase inward, the effective welding area will decrease, which is not conducive to the conductivity and strength of the structure. If the size of the aluminum alloy plate 1 is much larger than the size of the steel connecting surface 2, although the effective welding area can be increased to a certain extent, the excess flash needs to be dealt with after welding, and aluminum material is wasted. Therefore, the present invention preferably makes the two areas equal.

[0108] Step 5: This step specifically involves:

[0109] Step 5.1: As Figure 5 As shown, this embodiment determines the use of Figure 5 The welding is carried out along the zigzag path shown, and its starting point can be determined by the equipment control system as the center point O1 of the effective path area A2.

[0110] Step 5.2: In this embodiment, the L-spacing range is required to be 12-16mm. After adjustment, the spacing between Y-direction paths is determined to be L=15mm, n=240mm / 15=16, and the spacing between X-direction paths is L'=200mm / 16=12.5mm. L=15mm and L'=12.5mm are both within the above-mentioned range of 12-16mm, which meets the path spacing requirements. Then, the equipment control system generates a simulated welding path based on the above values.

[0111] Step 5.3: Determine the various process parameters of the friction stir welding equipment, including the welding head (stirring head) angle of 2°, welding pressure of 35-50KN, rotation speed of 800-1000rpm, and welding speed of 150-200mm / min. Then, start the friction stir welding equipment and move according to the simulated welding path generated in Step 5 to generate a bonding layer of the target thickness. The friction stir welding equipment is a well-known technology in the art and is a commercially available product.

[0112] After the above-mentioned connecting layer is generated, the present invention welds the aluminum rod to the connecting layer to form the final steel claw assembly product.

[0113] In this embodiment, the thickness of the intermetallic compound at the connection interface is less than 2 μm, the tensile strength of the joint is 197 MPa, and the shear strength is 142 MPa, which meets the technical requirements.

[0114] Example 2:

[0115] The difference between this embodiment and embodiment one is that this embodiment uses two types of aluminum alloy plates with different thicknesses for double-layer friction stir welding. The total thickness of the two aluminum alloy plates is 13mm. Assuming the thickness of the lower aluminum alloy plate is N, the thickness of the upper aluminum alloy plate is (13-N)mm.

[0116] In this embodiment, both layers of aluminum alloy plates are welded from the center to the edge using a U-shaped path, and the welding path planning for each layer of aluminum alloy plates is the same as in Embodiment 1. The control system sets the distance La between each Y-direction path of the lower aluminum alloy plate and generates the first simulated welding path, sets the distance Lb between each Y-direction path of the upper aluminum alloy plate and generates the second simulated welding path, and the fixing fixture 3 first presses down and fixes the lower aluminum alloy plate, and performs stir welding according to the first simulated welding path. In order to improve the bonding between layers, the surface of the lower aluminum alloy plate can be milled after welding. Then, the upper aluminum alloy plate is placed on the surface of the lower aluminum alloy plate and pressed down and fixed by the fixing fixture 3, and the stir welding of the upper aluminum alloy plate is completed according to the second simulated welding path.

[0117] The specific welding process parameters in this embodiment are as follows: welding head angle 1°, welding pressure 29~37KN, rotation speed 300~600rpm, welding speed 180~300mm / min.

[0118] In this embodiment, the thickness of the intermetallic compound at the connection interface is less than 2 μm, the tensile strength of the joint is 210 MPa, and the shear strength is 158 MPa, which meets the technical requirements.

[0119] Example 3:

[0120] The difference between this embodiment and Embodiment 1 is that:

[0121] In step four of this embodiment, additive manufacturing is used, and in step 5.1, the welding path adopts the following... Figure 6 The reciprocating U-shaped path shown has its starting point determined by the equipment control system as any corner point O2 of the effective path area A2.

[0122] In step 5.2 of this embodiment, the L spacing range is required to be 8-14mm. After adjustment, L=10mm and n'=240mm / 10=24. That is, the reciprocating U-shaped path in this embodiment includes 24 U-shaped paths connected in sequence. In addition, the length of each Y-direction path in this embodiment is the same, Y2=200mm.

[0123] In step 5.3 of this embodiment, the welding head angle of the additive manufacturing equipment is determined to be 0°, the welding pressure is 35-50KN, the rotation speed is 800-1000rpm, and the welding speed is 150-200mm / min. The additive manufacturing equipment is started and moves according to the simulated planning path in step 5.2 to generate the connecting layer of the target thickness.

[0124] In this embodiment, the welding material can be selected as 5mm aluminum alloy rods, powder, or wire, etc., as needed. The additive manufacturing process can be selected as continuous rod feeding additive manufacturing, continuous powder feeding additive manufacturing, or continuous wire feeding additive manufacturing, etc., all of which are well known in the art. In addition, the welding path in this embodiment is a single-sided feeding path from one side to the other. However, the welding path can also be a double-sided feeding path from both sides to the center, as needed. The endpoint of the double-sided feeding can be the center point O1 of the effective path area A2. In order to reduce weak connections between passes, after the single-layer welding additive manufacturing is completed, the welding path direction of the next layer can be rotated by 90 degrees so that the paths of adjacent layers are perpendicular.

[0125] After the above connecting layer is generated, the aluminum rod is welded to the connecting layer to form the final product.

[0126] In this embodiment, the thickness of the intermetallic compound at the connection interface is less than 2 μm, the tensile strength of the joint is 169 MPa, and the shear strength is 121 MPa, which meets the technical requirements.

[0127] Example 4:

[0128] This embodiment uses a 3mm aluminum alloy plate and a 5mm aluminum alloy rod for welding. The process combines friction stir welding and additive manufacturing. The control system sets the distance Lc between each Y-axis path of the friction stir welding and generates a simulated U-shaped welding path. Similarly, it sets the distance Ld between each Y-axis path of the additive manufacturing and generates a simulated reciprocating U-shaped welding path. The 3mm aluminum alloy plate is first fixed to the steel connecting surface 2 using a fixing fixture 3, and then subjected to friction stir welding along a simulated U-shaped welding path from the center to the edge, with a welding angle of 2°. The U-shaped path planning and other welding equipment process parameters are the same as in Embodiment 1. Next, this embodiment uses a 5mm rod for additive manufacturing welding on the 3mm aluminum alloy plate, with a simulated reciprocating U-shaped welding path from the edge to the edge, and a welding angle of 0°. The reciprocating U-shaped path planning and other welding equipment process parameters are the same as in Embodiment 3. After the connecting layer is generated, the aluminum rod is welded to the connecting layer to form the final product.

[0129] In this embodiment, the thickness of the intermetallic compound at the connection interface is less than 2 μm, the tensile strength of the joint is 207 MPa, and the shear strength is 150 MPa, which meets the technical requirements.

[0130] The friction stir welding and additive manufacturing equipment used in the above embodiments are all technologies known in the art and are commercially available products.

[0131] Compared to Figure 7 and Figure 9 Compared to existing transition block processes, this invention eliminates the need for auxiliary structures such as transition blocks, significantly simplifying the structure. Figure 8 and Figure 10 The present invention replaces the multi-layer, multi-pass welding process of traditional brazing with a one-time friction stir welding or additive manufacturing process to form an aluminum layer. This significantly simplifies the process and improves the automation level of the equipment. Furthermore, the friction stir welding or additive manufacturing process used in this invention is unaffected by environmental temperature, humidity, or operator skill, ensuring welding quality. Compared to brazing or transition block welding, this invention does not require gas protection and generates no welding fumes, thus improving the overall working environment.

Claims

1. A method for welding an aluminum-steel connecting layer for electrolytic aluminum, characterized in that: Includes the following steps: Step 1: Fix the steel parts to be welded using the fixing tooling blocks, and then pre-treat the connection surfaces of the steel parts; Step 2: Determine the effective welding area A1 on the steel component connection surface according to the following formula (1): A1=X1×Y1 X1=W-2D Y1=H-2D (1); In the above formula (1), W is the length of the steel connection surface, H is the width of the steel connection surface, and D is the amount of pressure of the fixed tooling pressure block on the steel connection surface; Step 3: Determine the effective path area A2 on the steel component connection surface according to the following formula (2): A2 = X2 × Y2 X2 = X1 - 2S - d Y2 = Y1 - 2S - d (2); In the above formula (2), S is the safety margin distance between the welding head and the fixed tooling block, and d is the diameter of the welding head; Step 4: Determine the welding process, which includes friction stir welding, additive manufacturing, or a combination of friction stir welding and additive manufacturing. Step 5: Determine the welding path shape according to the welding process, then plan the welding path and complete the welding, specifically as follows: Step 5.1: Determine the shape of the welding path. When using friction stir welding, the welding path shape is selected as a U-shaped path, and the starting point of the welding path is the center point O1 of the effective path area A2. When using additive manufacturing, the welding path shape is selected as a reciprocating U-shaped path, and the starting point of the welding path is any corner O2 of the effective path area A2. Step 5.2: Set the distance L between each Y-axis path of the welding path, and the equipment control system generates a simulated welding path based on the effective path area A2 determined in Step 3, the welding path shape and welding path starting point determined in Step 5.1, and the distance L. Step 5.3: Set the welding process parameters of the welding equipment, and then start the welding equipment to make the welding head move according to the simulated welding path generated in step 5.2 to complete the welding.

2. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: In step 5, when the welding path shape in step 5.1 is selected as a U-shaped path, the U-shaped path includes a Y-direction path and an X-direction path. In step 5.2, the spacing between each Y-direction path is set to L, and the U-shaped path is determined according to the following formula (3). X2 / L=n Y2 / n=L' (3; In the above formula (3), n is the number of path interval segments, and L' is the distance between each X-direction path.

3. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: In step five, when the welding path shape in step 5.1 is selected as a reciprocating U-shaped path, in step 5.2 the spacing between each Y-direction path is set to L, and the number of interval segments n' forming the reciprocating U-shaped path is determined according to the following formula (4): n'=X2 / L (4; At the same time, all Y-axis paths have the same length and are all Y2.

4. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: When the welding process in step four adopts the single-layer friction stir welding process, the single-layer aluminum alloy plate used as the welding material in step 5.1 is placed on the connecting surface of the steel part, and each side is pressed and fixed by the fixing tooling block. The area of ​​the single-layer aluminum alloy plate and the connecting surface of the steel part are equal, and the welding path shape is selected as a U-shaped path. The welding process parameters of the welding equipment in step 5.3 include a welding head angle of 2°, a welding pressure of 35~50KN, a rotation speed of 800~1000rpm, and a welding speed of 150~200mm / min.

5. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: When the welding process in step four uses a double-layer friction stir welding process, step five specifically involves: Step 5.1: Determine that the welding paths for both the lower and upper aluminum alloy plates are zigzag paths; Step 5.2: Set the distance La between each Y-axis path of the lower aluminum alloy plate and generate the first simulated welding path; set the distance Lb between each Y-axis path of the upper aluminum alloy plate and generate the second simulated welding path. Step 5.3: Place the lower aluminum alloy plate on the steel part connection surface, and fix each side by pressing it down with a fixing tooling block. Set the welding process parameters of the welding equipment, and then start the welding equipment to make the welding head move according to the first simulated welding path generated in step 5.2 to complete the welding. Then, the upper aluminum alloy plate is placed on the lower aluminum alloy plate, and each side is pressed and fixed by the fixing tooling blocks. The welding process parameters of the welding equipment are set, and then the welding equipment is started to make the welding head move according to the second simulated welding path generated in step 5.2 to complete the welding. The welding process parameters for the welding equipment set during the two welding operations include a welding head angle of 1°, a welding pressure of 29–37 KN, a rotation speed of 300–600 rpm, and a welding speed of 180–300 mm / min.

6. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 5, characterized in that: The areas of the lower aluminum alloy plate, the upper aluminum alloy plate, and the connecting surface of the steel component are equal.

7. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 5, characterized in that: In step 5.3, after the lower aluminum alloy plate is welded, its upper surface is first milled, and then the upper aluminum alloy plate is placed on the lower aluminum alloy plate.

8. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: When additive manufacturing is used in step four, the welding material used in step 5.1 is one of aluminum alloy rod, aluminum alloy powder or aluminum alloy wire, and the additive manufacturing process is one of continuous rod feeding additive manufacturing, continuous powder feeding additive manufacturing or connecting wire feeding additive manufacturing; the welding process parameters of the welding equipment in step 5.3 include welding head angle 0°, welding pressure 35~50KN, rotation speed 800~1000rpm, and welding speed 150~200mm / min.

9. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: When step four employs a combination of friction stir welding and additive manufacturing, step five specifically involves: Step 5.1: Determine that the solder for friction stir welding is a single-layer aluminum alloy plate and the welding path is a U-shaped path; determine that the solder for additive manufacturing is an aluminum alloy rod and the welding path is a reciprocating U-shaped path. Step 5.2: Set the distance Lc between each Y-axis path of friction stir welding and generate a simulated U-shaped welding path; set the distance Ld between each Y-axis path of additive manufacturing and generate a simulated reciprocating U-shaped welding path. Step 5.3: Place a single-layer aluminum alloy plate on the connecting surface of the steel part, and fix each side by pressing and fixing it with a fixing tooling block. Set the stirring friction welding process parameters of the welding equipment, including welding head angle 2°, welding pressure 35~50KN, rotation speed 800~1000rpm, and welding speed 150~200mm / min. Then the welding equipment is started, causing the welding head to move along the simulated U-shaped welding path generated in step 5.2 to complete the welding; Then, set the additive manufacturing welding process parameters for the welding equipment, including welding head angle of 0°, welding pressure of 35-50KN, rotation speed of 800-1000rpm, and welding speed of 150-200mm / min. The welding equipment is then started and moves according to the simulated reciprocating U-shaped welding path generated in step 5.2 to complete the welding.

10. The welding method for aluminum-steel connecting layers for electrolytic aluminum according to claim 1, characterized in that: In step one, the pretreatment of the steel component connection surface includes flatness and cleanliness pretreatment as well as modification pretreatment.

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