Diffusion bonding defect control method for multi-layer variable-thickness hollow structure
By designing an inner layer plate with a preformed height greater than the final forming height in a multi-layer variable thickness hollow structure, and combining the design of preformed molds and diffusion molds, the surface defect problem at the boundary of thickness gradients is solved, and the multi-layer variable thickness is achieved The efficient diffusion connection of the hollow structure eliminates edge depressions and improves forming accuracy and production efficiency.
Patent Information
- Application Number
- CN202411443973.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2024-12-13
AI Technical Summary
Multi-layer variable thickness hollow structures are prone to surface defects in diffusion connections, especially at the thickness gradient boundaries, which lead to material flow and high-temperature plastic deformation, resulting in irreversible stacking and edge depression.
By designing that the preformed height of the inner layer plate is greater than the final forming height, and using the corresponding preformed mold to preform the inner layer plate, then diffusely connect with the outer layer plate and reinforcement block, applying pressure to eliminate surface defects, ensuring the inner layer plate and the A tight fit between the laminate and the outer laminate.
It effectively suppresses the flow of the material due to pressure difference at high temperatures, eliminates the recesses of the rear edge of the diffusion connection, and improves the surface quality and overall forming accuracy of the multi-layer variable-thickness hollow structure.
Smart Images
Figure CN119115173A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of metal forming, and in particular to a method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure. Background Art
[0002] Superplastic forming / diffusion bonding (SPF / DB) technology is a component forming method that utilizes the characteristics of superplasticity and diffusion bonding of materials under specific conditions to achieve the integral forming of complex thin-walled parts. It has unique technical advantages in reducing the weight of aircraft structures, improving structural integrity and load-bearing efficiency. The titanium alloy superplastic forming / diffusion bonding combined process simplifies the manufacturing and assembly processes of parts, replaces the combined components fastened by traditional connection methods, saves manufacturing costs, shortens the manufacturing cycle, reduces structural weight, and achieves near-zero-residue forming. It has obvious advantages in manufacturing complex shapes and multi-layer hollow structures. Driven by the development of weapons and equipment, after nearly 50 years of basic research, development and verification tests, my country's titanium alloy SPF and SPF / DB manufacturing technologies have entered the engineering application stage and are widely used in the production of aircraft, aeroengines, missiles, spacecraft and other components. The application scope of SPF / DB components has developed from secondary load-bearing components to primary load-bearing components, rotating components, and hot end components, and the structural form has also developed from single-layer SPF components to SPF / DB double-layer, three-layer, and four-layer components.
[0003] Titanium alloy superplastic forming / diffusion bonding lightweight structures are widely used in aircraft structures, and the function of multi-layer reinforced load-bearing structures in aircraft is indispensable. Multi-layer sheets can be superplastically formed after diffusion bonding to obtain hollow load-bearing structures with various complex shapes and multiple functions.
[0004] Superplastic forming / diffusion bonding technology is a lightweight manufacturing technology for large and complex integral structures. It can effectively reduce the weight of the fuselage structure, improve the manufacturing accuracy of hollow sheet metal structures, and optimize the aircraft's tactical performance. It is a common requirement for the structural manufacturing of modern advanced fighter aircraft.
[0005] Multilayer variable thickness hollow complex structures are currently the focus of attention in the field of superplastic forming / diffusion bonding technology, such as Figure 1 As shown. As a type of multi-layer hollow complex structure, the surface quality assurance of the multi-layer variable thickness local reinforcement structure after diffusion bonding is the current technical difficulty. Since the high vacuum environment of the internal interface of the titanium alloy needs to be maintained during the thermal cycle of the titanium alloy diffusion bonding, there is a pressure difference between the inside and outside of the diffusion entity; at the same time, as the temperature increases, the material flow stress gradually decreases. When the internal and external pressure difference is greater than the material flow stress, there is a height difference in the plate due to the titanium alloy diffusion bonding structure with mixed layers and different thickness gradient characteristics, and there is a cavity in the thickness gradient area, such as Figure 2 As shown in Figure 1, the local material flows to the central layer under pressure, and high-temperature plastic deformation occurs at the micro level, causing irreversible accumulation of materials, resulting in diffusion connection edge depressions of multi-layer variable thickness reinforcement structures, such as Figure 3 shown.
[0006] Therefore, the inventor provides a method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure. Summary of the invention
[0007] (1) Technical issues to be solved
[0008] The embodiment of the present invention provides a method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure, which solves the technical problem that surface defects are easily generated at the thickness gradient boundary of a multi-layer variable thickness hollow structure during diffusion connection.
[0009] (2) Technical solution
[0010] The present invention provides a method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure, comprising the following steps:
[0011] Determine the pre-forming size of the inner layer plate according to the structural size characteristics of the multi-layer variable thickness hollow structural member; wherein the pre-forming height of the inner layer plate is greater than its final forming height;
[0012] Designing an inner layer plate preforming mold according to the preforming size of the inner layer plate, and using the inner layer plate preforming mold to preform the inner layer plate;
[0013] The preformed inner plate is subjected to surface treatment, and is sealed and welded with the outer plate and the reinforcing block located between the outer plate and the inner plate to form a blank for diffusion connection.
[0014] Furthermore, the difference between the pre-forming height of the inner layer plate and the final forming height of the inner layer plate is greater than 0.1 mm.
[0015] Furthermore, the difference between the pre-forming height of the inner layer plate and the final forming height of the inner layer plate is 0.5 mm.
[0016] Furthermore, the difference between the pre-forming height of the inner layer plate and the final forming height of the inner layer plate is greater than 2 mm.
[0017] Furthermore, before the inner layer plate preforming mold is used to preform the inner layer plate, the method further includes: blanking according to the size of the blank, and degreasing and pickling the inner layer plate obtained by blanking.
[0018] Furthermore, the preformed inner plate is subjected to surface treatment, and is sealed and welded with the outer plate and the reinforcing block between the outer plate and the inner plate to form a blank for diffusion connection, specifically comprising the following steps:
[0019] Preforming the inner layer sheet material using the inner layer sheet preforming die, and performing surface treatment on the formed inner layer sheet;
[0020] The inner plate, the outer plate and the reinforcing block after the surface treatment are coated with solder stopper and sealed and welded to obtain a diffusion blank;
[0021] The diffusion blank is diffusion-connected by using a diffusion die. During diffusion, the inner layer plate is upward and pressure is applied thereto, thereby obtaining a hollow structural member with surface defects eliminated.
[0022] Furthermore, the thickness of the reinforcement block is the same as the maximum height of the molding surface of the diffusion mold.
[0023] Furthermore, the thickness of the reinforcement block is greater than that of the outer layer plate and the inner layer plate.
[0024] (3) Beneficial effects
[0025] In summary, the present invention designs the preforming mold by designing the forming height of the inner layer plate after preforming to be greater than the height of the part after diffusion connection. Therefore, during diffusion connection, the inner layer plate is pressed against the outer layer plate under pressure, eliminating the cavity area between the inner layer plate and the outer layer plate, thereby inhibiting the flow of the outer layer plate toward the inner layer plate under the influence of the internal and external pressure difference when the outer layer plate is at high temperature, thereby eliminating the depression of the edge of the diffusion connection of the multi-layer variable thickness hollow structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0027] Figure 1 It is a structural schematic diagram of a multi-layered variable thickness hollow complex structural part;
[0028] Figure 2 It is a schematic diagram of the structure of the internal cavity of a multi-layered variable thickness hollow complex structure before diffusion;
[0029] Figure 3 It is a schematic diagram of the structure of a thickness gradient edge diffusion connection depression of a multi-layered variable thickness hollow complex structure;
[0030] Figure 4 It is a schematic flow chart of a method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure provided by an embodiment of the present invention;
[0031] Figure 5 is a structural schematic diagram of a diffusion-formed part provided in Example 1 of the present invention;
[0032] Figure 6 is a structural schematic diagram of a preforming mold provided by Example 1 of the present invention;
[0033] Figure 7 is a structural schematic diagram of a diffusion mold provided by Example 1 of the present invention;
[0034] Figure 8 It is a structural schematic diagram of a diffusion blank provided in Example 1 of the present invention;
[0035] Fig. 9 It is a schematic diagram of the pressure direction of a diffusion bonding mechanical pressure provided in Example 1 of the present invention.
[0036] In the figure:
[0037] 1-blank cavity area; 2-diffusion connection edge depression; 3-inner plate; 4-outer plate; 5-reinforcement block; 6-preforming mold; 7-diffusion mold; 8-diffusion blank; P-pressure. DETAILED DESCRIPTION
[0038] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modification, replacement and improvement of parts, components and connection modes without departing from the spirit of the present invention.
[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0040] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0041] Figure 4 is a flow chart of a multi-layer variable thickness hollow structure diffusion connection defect control method provided by an embodiment of the present invention, see Figure 4 , the control method may include the following steps:
[0042] S100, determining the pre-forming size of the inner layer plate according to the structural size characteristics of the multi-layer variable thickness hollow structural member; wherein the pre-forming height of the inner layer plate is greater than its final forming height.
[0043] Specifically, the difference between the preformed height of the inner plate and the final formed height of the inner plate is greater than 0.1 mm. Furthermore, the difference between the preformed height of the inner plate and the final formed height of the inner plate is greater than 2 mm. It should be noted that when the height difference is less than 0.1 mm, the effect of eliminating the cavity area between the inner and outer plates is poor; when the height difference is greater than 2 mm, it is difficult to control the deformation of the multi-layer variable thickness hollow structural member. Therefore, the appropriate interval is selected as 0.1 to 2 mm.
[0044] S200, designing an inner layer plate preforming mold according to the preforming size of the inner layer plate, and using the inner layer plate preforming mold to preform the inner layer plate.
[0045] Specifically, before the inner layer plate preforming mold is used to preform the inner layer plate, the process also includes: blanking according to the size of the blank, and degreasing and pickling the blanked inner layer plate.
[0046] S300, performing surface treatment on the preformed inner plate, and sealing and welding the preform with the outer plate and the reinforcing block between the outer plate and the inner plate to perform diffusion bonding.
[0047] Specifically, step S300 may include the following steps:
[0048] S301, preforming the inner layer sheet material using an inner layer sheet preforming mold, and performing surface treatment on the formed inner layer sheet;
[0049] S302, coating the inner plate, the outer plate and the reinforcing block with solder stopper after surface treatment and sealing and welding the blank to obtain a diffusion blank;
[0050] S303, using a diffusion mold to perform diffusion connection on the diffusion blank, during diffusion, the inner layer plate is upward and pressure is applied thereto, so as to obtain a hollow structural part with surface defects eliminated.
[0051] Furthermore, the height difference between the top of the inner plate and the top of the reinforcing block is 0.5 mm, the thickness of the reinforcing block is the same as the maximum height of the profile of the diffusion mold, and the thickness of the reinforcing block is greater than that of the outer plate and the inner plate.
[0052] This method can effectively alleviate the non-uniform flow of materials caused by variable thickness gradient during the diffusion bonding process, thereby solving surface defects such as concave grooves generated at the thickness gradient boundary after diffusion bonding. At the same time, unlike the traditional vacuum diffusion bonding process for equal thickness plates, this method can achieve diffusion bonding of multi-layer variable thickness gradient complex structures, and then achieve the overall forming of multi-layer variable thickness gradient complex structures, greatly improving production efficiency and reducing production costs.
[0053] Example 1
[0054] In this embodiment, the designed diffusion blank is composed of three layers of TC4 plates, including inner and outer panels with a thickness of 2 mm, and a middle reinforcement block with a thickness of 10 mm. The panel size is 400 mm*400 mm, and the reinforcement block size is 100 mm*100 mm.
[0055] Step 1 is to design the pre-forming mold and the diffusion mold. The outer surface of the designed diffused part is extracted as the surface of the diffusion mold. The surface is offset outward by 0.5 mm as the pre-forming mold surface, so as to obtain the required pre-forming mold and diffusion mold. Figure 5 As shown, the profile of the preforming die 6 is as shown in Figure 6 As shown, the profile of the diffusion mold 7 is as shown in Figure 7 As shown in;
[0056] Step 2 is to cut the blank according to the size of the blank, remove oil and pickle it, and then use the preforming mold 6 to preform the inner layer plate, and then perform surface treatment;
[0057] Step 3 is to use the preformed inner plate 3, outer plate 4 and reinforcing block 5 to apply solder stopper and seal the assembly to obtain Figure 8 The diffusion blank 8 shown has a height difference of 0.5 mm between the top of the inner plate 3 and the top of the reinforcing block 5;
[0058] Step 4 is to use the diffusion mold 7 to diffusely connect the diffusion blank 8. During diffusion, the inner layer plate 3 is upward and a mechanical pressure P is applied to it. The direction of application of the mechanical pressure P is as follows: Fig. 9 As shown, the final diffused part is obtained with surface defects eliminated.
[0059] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.
[0060] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims
1. A method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure, characterized in that: The method comprises the following steps: Determine the pre-forming size of the inner layer plate according to the structural size characteristics of the multi-layer variable thickness hollow structural member; wherein the pre-forming height of the inner layer plate is greater than its final forming height; Designing an inner layer plate preforming mold according to the preforming size of the inner layer plate, and using the inner layer plate preforming mold to preform the inner layer plate; The preformed inner plate is subjected to surface treatment, and is sealed and welded with the outer plate and the reinforcing block located between the outer plate and the inner plate to form a blank for diffusion connection.
2. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 1, characterized in that: The difference between the pre-forming height of the inner layer plate and the final forming height of the inner layer plate is greater than 0.1 mm.
3. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 2, characterized in that: The difference between the pre-forming height of the inner layer plate and the final forming height of the inner layer plate is 0.5 mm.
4. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 3, characterized in that: The difference between the pre-forming height of the inner layer plate and the final forming height of the inner layer plate is less than 2 mm.
5. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 1, characterized in that: Before the inner layer plate preforming mold is used to preform the inner layer plate, the method further includes: blanking according to the size of the blank, and degreasing and pickling the inner layer plate obtained by blanking.
6. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 1, characterized in that: The process of performing surface treatment on the preformed inner plate and sealing and welding the preform with the outer plate and the reinforcement block between the outer plate and the inner plate to perform diffusion connection specifically includes the following steps: Preforming the inner layer sheet material using the inner layer sheet preforming die, and performing surface treatment on the formed inner layer sheet; The inner plate, the outer plate and the reinforcing block after the surface treatment are coated with solder stopper and sealed and welded to obtain a diffusion blank; The diffusion blank is diffusion-connected by using a diffusion die. During diffusion, the inner layer plate is upward and pressure is applied thereto, thereby obtaining a hollow structural member with surface defects eliminated.
7. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 6, characterized in that: The thickness of the reinforcement block is the same as the maximum height of the molding surface of the diffusion mold.
8. The method for controlling diffusion connection defects of a multi-layer variable thickness hollow structure according to claim 6, characterized in that: The thickness of the reinforcement block is greater than that of the outer layer plate and the inner layer plate.