Aluminum alloy seat cabin cast-weld composite forming method

Abstract

The aluminum alloy cabin cast-weld composite forming method comprises the following steps: 1) forming a cabin main body structure by using a low-pressure casting forming process; 2) marking and spot welding left and right upper side beams and internal reinforcing supports on the cabin main body structure, and after completion, welding each weld to form a first welded assembly; 3) using segmented forming for the skeletons on both sides of the cabin main body structure, positioning and rigidly constraining the segmented skeletons and the first welded assembly through a "positioning boss + bottom support + upper reinforcing beam" combined tooling, then welding each weld to form a second welded assembly; 4) assembling and welding each skin on the second welded assembly to complete the cabin forming; and 5) performing heat treatment and stress relief treatment on the cast-weld formed cabin.

Description

Technical Field

[0001] This invention relates to aluminum alloy cockpit product forming technology, specifically to an aluminum alloy cockpit casting and welding composite forming method. Background Technology

[0002] Aluminum alloy cockpits are crucial load-bearing structures for servo launch systems, providing a stable platform for inertial navigation, launch control, power supply, servo drives, and other upper-level equipment. They also offer accurate installation interfaces for the transmission system and can withstand the impact of missile launches. Cockpits are typically large-scale frame structures, consisting of a central main beam, side frames, and skin. The components are made of 5A06 material, machined from sheet metal, and then welded together using manual tungsten inert gas welding.

[0003] Generally speaking, aluminum alloy cockpits have complex structures with large differences in wall thickness, and various joint types such as corner joints, butt joints, and lap joints. There are numerous welds, and some structures require all-position welding. The quality of the weld joints and the precision of the post-weld forming are crucial. Furthermore, aluminum alloys require acid pickling to remove the oxide film before welding, rigid tooling is needed for component welding, and stress relief heat treatment is required after welding. Welded joints require magnetic particle or dye penetrant testing, and large machining allowances are often reserved for areas to be processed. The product process is cumbersome, involves numerous cross-process coordination tasks, and presents significant challenges in production planning and cycle time management.

[0004] It is evident that traditional component welding processes are not very efficient or economical, resulting in inconsistent product quality and poor appearance, making it difficult to meet the demands of high-performance, high-efficiency equipment production. Summary of the Invention

[0005] The purpose of this invention is to provide a method for casting and welding composite molding of aluminum alloy cockpits, which significantly improves manufacturability, enhances product consistency, and increases production efficiency.

[0006] To achieve the above objectives, the present invention provides a method for casting and welding composite molding of an aluminum alloy cockpit, comprising: 1) casting the main structure of the cockpit using a low-pressure casting process; 2) marking and spot welding the left and right upper side beams and internal reinforcing brackets on the main structure of the cockpit, and welding each weld after assembly to form a first welding assembly; 3) using segmented molding of the frame on both sides of the main structure of the cockpit, positioning and rigidly constraining the segmented frame and the first welding assembly using a combination of "positioning boss + bottom support + upper reinforcing beam" tooling, and then welding each weld to form a second welding assembly; 4) welding each skin onto the second welding assembly to complete the cockpit molding; 5) performing heat treatment and stress relief treatment on the cast and welded cockpit.

[0007] Preferably, in step 1), the main cockpit structure is made of ZL101A material. Considering the product's large size, multiple planes, and significant wall thickness differences, a low-pressure casting process is used. Uniformly spaced vertical gating channels are installed on both sides of the main cockpit structure, chills are placed in thicker internal sections, and risers are used in critical areas such as the slewing bearing for feeding. Furthermore, the gating system design strives for stable aluminum molten metal filling, balancing the filling and feeding processes, and balancing the temperature field distribution of the casting to create conditions for sequential solidification. Furthermore, the casting process strictly controls the alloy melting process, adjusting the alloy composition and adding trace amounts of Ti, B, and Zr modifying elements to refine the casting microstructure. Finally, after casting, the part undergoes demolding, scribing and measurement, cleaning and grinding, radiographic testing, and fluorescent inspection. The process includes inspection and surface testing to evaluate the forming accuracy and internal and external quality of the casting. Furthermore, during the machining of the casting blank, the exposed surfaces of the cockpit main structure, such as the sides and top, are machined as a whole to remove casting risers and gating gates, revealing the metallic luster. Internal features such as reinforcing ribs and wiring holes are formed in one casting step, eliminating the need for material reduction machining. Removing casting allowances such as risers and gating gates from the outer surface of the casting through machining helps control the overall forming accuracy of the cockpit main structure, especially optimizing the wall thickness distribution of the large side panels, and providing favorable conditions for subsequent welding to the structural frames on both sides. Positioning bosses are pre-reserved on the machined surfaces on both sides of the cockpit main structure for quick installation and positioning of the side frames, reducing the workload of fitter marking and improving assembly processability.

[0008] Preferably, in step 2), firstly, the left and right upper beams and each reinforcing bracket are formed using 5A06 aluminum plates or finished rectangular aluminum tubes; secondly, the oil stains and other contaminants on each assembly part and the part to be welded are cleaned; thirdly, the assembly is carried out in the order of inside first and then top, and the positioning spot welding is performed after verifying that the dimensions are correct, and tungsten inert gas welding is used for welding; finally, the welds are welded in place according to the order of "welding the two ends first, then the middle, welding the inside first, then the outside, welding the short weld first, then the long weld".

[0009] Preferably, in step 3), firstly, the frame on both sides of the cockpit is formed in sections. The frame is welded from 5A06 aluminum material and corrected after welding to ensure the accuracy of shape and position dimensions. Secondly, the oil stains and other contaminants on the four sets of frames and the parts to be welded in the first welding assembly are cleaned. Thirdly, the first welding assembly is fastened to the work platform. The four sets of segmented frames are positioned and installed through the positioning bosses on both sides of the main structure of the cockpit, the support fixtures at the bottom of the frame and the process reinforcement beams at the top, and are rigidly connected to the first welding assembly. Finally, each weld is completed according to the following sequence: "weld the two ends first, then the middle; weld the short weld first, then the long weld; weld the butt joint first, then the lap or corner joint; weld the side with sparse weld first, then the side with dense weld; weld the parallel welds simultaneously and symmetrically in the same direction on both sides." This completes the second welding assembly.

[0010] Preferably, in step 4), firstly, each skin is connected to the second welding assembly by intermittent welding, and the weld points are firm and without false welds; secondly, the assembly is shaped as a whole after welding to ensure that the flatness of the upper surface of the cockpit does not exceed 2mm.

[0011] Preferably, the main body of the cockpit has a symmetrical frame on both sides. When the symmetrical frames are welded together, a combination of "back-to-back spot welding + process struts" can be used to constrain the components and achieve efficient production of segmented parts.

[0012] Preferably, in step 5), firstly, the cast-welded composite molded cockpit undergoes graded solution treatment by holding at 480℃ for 1 hour and at 545℃ for 12 hours; secondly, an aging treatment by holding at 165℃ for 8 hours can meet the product shape control requirements; finally, the product is finished and shaped to achieve the cast-welded composite molding of the cockpit.

[0013] Preferably, during the assembly and welding of each frame group, welding shrinkage allowance should be reserved in each direction to compensate for the overall welding shrinkage of the frame. A 1mm to 2mm shrinkage allowance is reserved in the height direction of the frame, causing the frame sides to arch upwards, thus controlling deformation. The frame is connected to the main cockpit structure by fillet welds, typically single-layer single-pass or two-layer three-pass welds. A weld shrinkage allowance of 1.5mm / meter to 2mm / meter is set in the length and width directions of the frame.

[0014] Preferably, for welding between ZL101A (T4 state) and 5A06 dissimilar materials, the Al-Si series ER4043 welding wire with strong versatility is used to ensure joint strength and reduce hot cracking sensitivity; for welding between 5A06 homogeneous materials, the Al-Mg series ER5356 welding wire is used.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are:

[0016] The aluminum alloy cockpit casting-welding composite molding method of this invention achieves efficient molding of large-size complex cockpits through a composite process of "main frame casting + segmented welding of the skeleton and skin"; controlled shape of the cast main frame is achieved through low-pressure casting and metallurgical composition control; the skeleton can be quickly and accurately positioned through pre-set positioning bosses and support fixtures; precise skeleton molding is achieved through "back-to-back" pairing constraints and shrinkage allowance; and shape control of the product is achieved through post-weld heat treatment transformation and stress relief treatment. Ultimately, this invention effectively improves the manufacturability of complex aluminum alloy cockpits, enhances product appearance, and improves product quality consistency. Attached Figure Description

[0017] The aluminum alloy cockpit casting-welding composite molding method of the present invention is given by the following embodiments and figures.

[0018] Figure 1 This is a schematic diagram of the main structure of the cast cockpit in this invention.

[0019] Figure 2 This is a schematic diagram of the assembly and welding of the main cockpit structure and the reinforcing bracket in this invention.

[0020] Figure 3 This is a schematic diagram of the segmented molding of the skeleton in this invention.

[0021] Figure 4 This is a schematic diagram of the first welding component and the skeleton assembly in this invention.

[0022] Figure 5 This is a schematic diagram of the first welding component and the frame being assembled and welded together in this invention.

[0023] Figure 6 This is a schematic diagram of the cast-welded composite molding cockpit in this invention. Detailed Implementation

[0024] The following will combine Figures 1-6 The aluminum alloy cockpit casting-welding composite molding method of the present invention will be described in further detail.

[0025] The aluminum alloy cockpit casting-welding composite molding method of this embodiment includes:

[0026] 1) The main structure of the cockpit 11 is formed by low-pressure sand core casting;

[0027] First, core-making and molding are carried out using resin sand cores and wooden molds. Second, ZL101A aluminum ingots are smelted, treated with Ti, B, and Zr element modification, refined and degassed before casting. Third, demolding is performed and internal and external defect inspections are conducted. The slewing bearing and transmission device installation area 111 are verified by radiographic testing, while other parts are inspected by fluorescence. Finally, the casting blank is machined and shaped. The outer surfaces 113 and upper surfaces 114 of the two large side panels of the cockpit main structure are machined as a whole. Positioning bosses 115 are reserved on the outer side of the side panels. The positions of the positioning bosses 115 match the welding positions of the segmented frame (31, 41, 51, 61). The internal reinforcing ribs and cable passage holes 112 of the cockpit are formed by casting. Figure 1 As shown;

[0028] 2) On the completed main structure of the cockpit, lines are drawn and the reinforcing supports and side beams are attached sequentially to form the first welding assembly 21, such as... Figure 2 As shown;

[0029] First, mark and install reinforcing brackets I / II (211 / 212), middle reinforcing brackets I / II (213 / 214), upper right side beams I / II (221 / 222), and upper left side beams I / II (223 / 224) on the main structure of the cockpit. After verifying that the dimensions are correct, spot weld them. Second, install upper reinforcing brackets I / II (231 / 232) and middle reinforcing brackets III / IV (233 / 234). Before installing the upper reinforcing brackets, prioritize welding the interference welds. Finally, after the assembly is completed, weld in the following order: lower reinforcing brackets - upper left and right side beams - upper reinforcing brackets, both ends reinforcing brackets - middle reinforcing brackets, and internal welds - external welds.

[0030] 3) The main body structure of the cockpit is constructed in segments. The first frame 31 and the third frame 51 are symmetrical, and the second frame 41 and the fourth frame 61 are symmetrical. Figure 3 As shown, when welding the symmetrical skeleton, a combination of "back-to-back spot welding + process struts" is used for constraint to reduce welding deformation.

[0031] The forming process of the second welding assembly is as follows: First, the first welding assembly is fixed to the platform with screws, pressure plates, and nuts, with a fastening point on each side and in the middle to balance the welding stress; second, the segmented skeletons are positioned using a combination of "positioning boss + bottom support + upper reinforcing beam" fixtures; third, each skeleton is reserved with a 1mm to 2mm shrinkage allowance in the height direction to make it arched, which plays a role in anti-deformation control, and the skeletons are set with a weld shrinkage allowance of 1.5mm per meter to 2mm per meter in the length and width directions; finally, multiple welders are used to weld each seam properly by symmetrically welding from both ends of the workpiece to the middle; manual TIG welding is used for welding, and ER4043 welding wire is used for welding dissimilar materials ZL101A (T4 state) and 5A06; ER5356 welding wire is used for welding 5A06 of the same material. The second welding assembly 71 is as follows. Figure 5 As shown;

[0032] 4) Connect each skin panel to the second welding assembly using intermittent welding. The intermittent welds should be 100mm long and spaced 50mm apart, with strong welds and no incomplete welds. After welding, the assembly should be reshaped to ensure that the flatness of the upper surface of the cockpit does not exceed 2mm. Figure 6 As shown;

[0033] 5) The cockpit 81, which was cast and welded in step 4), is subjected to heat treatment for transformation and stress relief.

[0034] First, the cockpit formed by casting and welding in step 4) is subjected to graded solution treatment at 480℃ for 1 hour and at 545℃ for 12 hours, and then vertically immersed in water; then, it is subjected to aging stress relief at 165℃ for 8 hours; finally, the product is finely shaped to achieve composite casting and welding of the cockpit.

[0035] This invention achieves efficient molding of large-sized, complex cockpits through a composite process of "main frame casting + segmented welding of the skeleton and skin." Low-pressure casting and metallurgical composition control ensure the shape and properties of the cast main frame are controlled. Pre-positioned bosses and supporting fixtures enable rapid and accurate positioning of the skeleton. Back-to-back pairing constraints and shrinkage allowance allowance achieve precise skeleton molding. Post-weld heat treatment and stress relief processes control the product's shape and properties. Ultimately, this invention effectively improves the manufacturability of complex aluminum alloy cockpits, enhances product appearance, and improves product quality consistency.

[0036] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for composite casting and welding of aluminum alloy cockpits, characterized in that, include: 1) The main structure of the cockpit is cast using a low-pressure casting process; 2) Mark and spot weld the left and right upper side beams and internal reinforcing brackets on the main structure of the cockpit. After the assembly is completed, weld all the welds to form the first welding assembly. The sheet metal or machined upper beams and reinforcing brackets are assembled onto the main cockpit structure in the order of first the inside and then the top. After the positioning welding is completed, each weld is properly welded in the order of "lower reinforcing bracket - left and right upper beams - upper reinforcing bracket", "both end reinforcing brackets - middle reinforcing bracket", and "internal weld - external weld" to form the first welded assembly. 3) The frame on both sides of the main structure of the cockpit is formed in sections. The segmented frame and the first welding assembly are positioned and rigidly constrained by a combination of "positioning boss + bottom support + upper reinforcing beam" tooling. Then, each weld is welded to form the second welding assembly. The symmetrical frames on both sides of the main cockpit structure are formed in sections. During assembly welding, a combination of "back-to-back spot welding + process struts" is used to constrain the frames and reduce welding deformation. After each frame is formed, it is positioned on the first welding assembly using a combination of "positioning boss + bottom support + upper reinforcing beam". The second welding assembly is formed by welding each seam in the following order: "weld the two ends first, then the middle; weld the short seam first, then the long seam; weld the butt joint first, then the lap or corner joint; weld the side with sparse seams first, then the side with dense seams; and weld the parallel seams symmetrically on both sides in the same direction at the same time". 4) Weld each skin onto the second welding assembly to complete the cockpit molding; 5) Perform heat treatment and stress relief on the cast and welded cockpit; After undergoing graded solution treatment at 480℃ for 1 hour and 545℃ for 12 hours, the cabin obtained in step 4) is vertically immersed in water; subsequently, it is subjected to aging stress relief at 165℃ for 8 hours; finally, it is fine-tuned and shaped to achieve composite molding of the cabin by casting and welding.

2. The aluminum alloy cockpit casting-welding composite molding method as described in claim 1, characterized in that, In step 1), the main structure of the cockpit is made of ZL101A material and formed by low-pressure sand casting. After the casting is poured, solidified and demolded, it is inspected for internal and external defects and then machined. The exposed surfaces on both sides of the main cockpit structure are machined as a whole to remove the casting risers and expose the metallic luster. The internal reinforcing ribs and wire holes of the cockpit are formed by casting. The outer side of the main cockpit structure wall panel is reserved with positioning bosses for quick positioning and assembly of the segmented frame.

3. The aluminum alloy cockpit casting-welding composite molding method as described in claim 1, characterized in that, In step 4), the skin is connected to the second welding component through intermittent welds, and the overall shape is corrected after welding to ensure the product forming accuracy.

4. The aluminum alloy cockpit casting-welding composite molding method as described in claim 1 or 3, characterized in that, In steps 3) and 4), tungsten inert gas welding is used for welding. ER4043 welding wire is used for welding dissimilar materials such as T4 state ZL101A and 5A06, and ER5356 welding wire is used for welding the same material such as 5A06.

5. The aluminum alloy cockpit casting-welding composite molding method as described in claim 1, characterized in that, When the second welding component is formed, each frame is reserved with a shrinkage allowance of 1~2mm in the height direction to make it arched, which plays a role in anti-deformation control; each frame is set with a weld shrinkage allowance of 1.5mm / meter to 2mm / meter in the length and width directions.

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