Pressurizing assembly for diffusion welding of curved workpiece, and apparatus and welding method

Abstract

A pressurizing assembly for diffusion welding of a curved workpiece. The pressurizing assembly is configured to connect to a pressurizing system to implement pressurization of a curved workpiece. The pressurizing assembly comprises a dot-matrix pressurizing member (1) and induction heating members, wherein the dot-matrix pressurizing member comprises a drive base (11) and several pressurizing rods (13), the drive base being provided with several mounting positions (12) distributed in a dot-matrix pattern, and one pressurizing rod being mounted at one mounting position and all the pressurizing rods being parallel to each other; the drive base independently drives the pressurizing rod mounted at each mounting position, thus enabling independent local pressurization of the curved workpiece; and an induction heating member is arranged close to a free end of each pressurizing rod, thus enabling independent local heating of the curved workpiece. Further disclosed is a diffusion welding apparatus for a curved workpiece. A diffusion welding method for a curved workpiece, comprising: by means of the dot-matrix pressurizing member and the induction heating members of the pressurizing assembly, performing independent zoned pressurization and heating of a workpiece to be welded, so as to perform pressure welding. By means of a dot-matrix distribution pattern and an independent control mode, the pressurizing assembly enables zoned adjustment of a pressurizing process on the basis of the actual shape of the surface of a workpiece and required compressive stress and temperature conditions, thus effectively improving the diffusion welding effect and efficiency of a workpiece having a non-flat surface.

Description

Pressurized assembly, equipment and welding method for diffusion welding of curved workpieces

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 15, 2024, with application number 2024100510629 and application name “Pressure assembly, equipment and welding method for diffusion welding of curved workpieces”, the entire contents of which are incorporated by reference into the application. Technical Field

[0002] The present application relates to the technical field of diffusion welding forming, and in particular to a pressurizing component, equipment and welding method of a diffusion welding device for curved workpieces. Background Art

[0003] Diffusion welding is a solid-state joining technique in which the two workpieces to be welded are compacted together and heated in a vacuum or inert gas environment. This causes plastic deformation on the surfaces of the workpieces, achieving close contact. Subsequently, heating and insulation are applied to allow atoms on both sides of the workpiece contact surfaces to diffuse into each other, forming a metallurgical bond. Diffusion welding allows the entire interface to be joined, which is crucial for achieving high-strength internal connections between workpieces. Furthermore, since the base material undergoes no phase transition from melting to solidification during welding, the properties of the base material itself remain unchanged, and the strength of the welded joint approaches or even reaches that of the base material. Diffusion welding is suitable for joining most metals, some non-metallic materials such as ceramics, glass, and silicon, as well as dissimilar metals and even metal-nonmetal connections.

[0004] At present, conventional diffusion welding equipment is only suitable for diffusion welding forming of flat workpieces. By applying a small number of pressure points to a whole piece of solder mask pressure plate, this method can only apply uniform and consistent compressive stress to the welding workpiece. The workpiece to be welded is heated by the side wall heating component, which cannot effectively heat the upper and lower surfaces of the workpiece. Therefore, the current diffusion welding equipment and methods cannot meet the needs of pressure zone adjustment under non-uniform temperature field conditions and cannot be applied to curved workpieces. It is necessary to propose a device that can adjust the pressure zone and is suitable for diffusion welding equipment and methods of various complex curved workpieces.

[0005] Application Contents

[0006] The main purpose of the present application is to provide a pressurizing component, equipment and welding method for a curved workpiece diffusion welding device, so as to solve the problem that the existing diffusion welding equipment has poor diffusion welding effect on irregular curved surfaces.

[0007] To achieve the above objectives, the present application provides the following technical solution: a pressurizing assembly for diffusion welding of curved workpieces, the pressurizing assembly being used to pressurize the curved workpiece after being connected to a pressurizing system, the pressurizing assembly comprising:

[0008] A lattice pressurizing member includes a driving base and a plurality of pressurizing rods. The driving base is provided with a plurality of mounting positions distributed in a lattice, a pressurizing rod is installed on a mounting position and all pressurizing rods are parallel to each other; the driving base independently drives the pressurizing rod installed on each mounting position to independently pressurize the local area of ​​the curved workpiece.

[0009] Optionally, the pressurizing assembly further comprises an induction heating element, which is arranged near the free end of each pressurizing rod to heat the curved surface of the workpiece in a zoned manner.

[0010] Optionally, the pressurizing assembly also includes a curved surface contact piece, which includes a pressure plate base fixedly connected to the free end of each pressurizing rod, and each pressure plate base is provided with a multi-stage movable pressure plate combination at one end away from the pressurizing rod, and the movable pressure plate combination includes a plurality of layered movable pressure plates, and each pressure plate base is movably connected to the adjacent movable pressure plate and each movable pressure plate through electromagnetic adsorption and mutually cooperating joint sockets.

[0011] Optionally, the joint socket is a cylindrical concave cavity and is arranged on the side of each pressure plate base away from the pressure rod and on the side of each movable pressure plate close to the next level movable pressure plate. Each movable pressure plate cooperates with the cylindrical concave cavity and moves in the cylindrical concave cavity under the action of external force. The number of movable pressure plates at each level increases step by step along the direction from the pressure plate base to the curved workpiece.

[0012] Optionally, the joint socket is a spherical cavity, which is arranged on the side of each pressure plate base away from the pressure rod and on the side of each movable pressure plate close to the next level movable pressure plate. Each movable pressure plate cooperates with the spherical cavity and moves in the spherical cavity under the action of external force. The number of movable pressure plates at each level increases step by step along the direction from the pressure plate base to the curved workpiece.

[0013] Optionally, a solder resist plate is provided on the movable pressing plate of the movable pressing plate assembly that contacts the curved workpiece.

[0014] Optionally, the driving base drives each pressurizing rod by hydraulic pressure, pneumatic pressure or mechanical propulsion.

[0015] Optionally, the dot matrix distribution outline of the installation position is a regular polygon.

[0016] On the other hand, the present application also provides a curved workpiece diffusion welding device, which includes a pressurizing system, the output of which is connected to any of the pressurizing components described above to drive the pressurizing component to pressurize the workpiece to be welded.

[0017] In another aspect, the present application further provides a method for diffusion welding a curved workpiece, the method being applied to a curved workpiece diffusion welding device, the curved workpiece diffusion welding device comprising a pressurizing system and a pressurizing assembly as described in any one of the preceding items, wherein the output of the pressurizing system is connected to the pressurizing assembly, wherein the method comprises:

[0018] Determine the maximum thermal stress value ΔS of the workpiece to be welded under uniform heating conditions max Whether it exceeds the preset allowable limit ΔS lim ;

[0019] If so, heating is performed according to a preset zone heating temperature, and whether the maximum thermal stress value ΔSmax of the workpiece to be welded under the zone heating condition exceeds a preset allowable limit value ΔSlim is used as an iteration condition to determine the zone heating temperature of the upper and lower walls and the temperature distribution field of the workpiece to be welded;

[0020] Determining the required applied stress in each area of ​​the workpiece to be welded according to the determined upper and lower wall zone heating temperatures and the first temperature distribution field of the workpiece to be welded;

[0021] Selecting a matching lattice pressurizing member according to the determined required applied stress and the curved surface condition of the workpiece to be welded;

[0022] The lattice pressurizing element and the induction heating element of the pressurizing assembly are used to independently pressurize and heat the partitions of the workpiece to be welded to perform pressure welding.

[0023] Optionally, the maximum thermal stress value ΔS of the workpiece to be welded under uniform heating conditions is determined. max Whether it exceeds the preset allowable limit ΔS lim In the step, the uniform heating condition includes uniformly heating the side wall surface of the workpiece to be welded and uniformly heating the upper and lower wall surfaces of the workpiece to be welded.

[0024] Optionally, in the step of determining the required applied stress of each region of the workpiece to be welded based on the determined upper and lower wall partition heating temperatures and the first temperature distribution field of the workpiece to be welded, the required applied stress of each region of the workpiece to be welded is determined by the following model;

[0025] Among them, Q local Indicates the local diffusion welding strength of the workpiece, T local Represents the local temperature of the workpiece, σ local It represents the local stress value of the workpiece, C0 represents the normalization coefficient, which is a constant, n is the normalization exponent, E represents the volume diffusion activation energy, a constant related to the material type, and R represents the gas constant.

[0026] The pressurizing assembly for diffusion welding of curved workpieces of the present application is used to pressurize the curved workpiece after being connected to the pressurizing system, and includes a lattice pressurizing component and an induction heating component. The lattice pressurizing component includes a driving base and a plurality of pressurizing rods. The driving base is provided with a plurality of mounting positions distributed in a lattice, a pressurizing rod is installed on a mounting position and all pressurizing rods are parallel to each other; the driving base independently drives the pressurizing rod installed on each mounting position to independently pressurize the local part of the curved workpiece. The pressure component of the present application is formed by arranging a number of mounting positions distributed in a dot matrix on the same surface on the driving base and installing a pressure rod on each mounting position to form a dot matrix pressure member, wherein the dot matrix pressure member is controlled by the pressure system, and the pressure system independently controls the pressure rod on each mounting position through the driving base without interfering with each other, so that when pressure welding a curved workpiece, the applied stress of each area of ​​the pressure component can be adjusted according to the actual contour of the curved workpiece; at the same time, by arranging an induction heating element near the free end of each pressure rod, the curved surface of the curved workpiece is heated in a zoned manner, thereby meeting the different heating temperatures required for each curved surface area of ​​the irregular curved workpiece. In summary, the pressure component of the present application solves the problem that the plane equivalent pressure component in the current diffusion welding cannot perform pressure welding on the curved workpiece, and realizes effective pressure welding of the curved workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a simplified structural diagram of a diffusion welding device in the prior art;

[0028] FIG2 is a diagram illustrating the principle of pressure welding performed by diffusion welding equipment in the prior art;

[0029] FIG3 is a schematic diagram of the temperature distribution formed on the workpiece to be welded by the side wall heating method of the diffusion welding equipment in the prior art;

[0030] FIG4 is a schematic structural diagram of an embodiment of a pressurizing assembly of the present application;

[0031] FIG5 is a simplified and enlarged structural diagram of the pressurizing assembly in the embodiment of FIG4 ;

[0032] FIG6 is a schematic structural diagram of an embodiment of a curved surface contact member of the present application;

[0033] FIG7 is a schematic structural diagram of another embodiment of the curved surface contact member of the present application;

[0034] FIG8 is a schematic diagram of the steps of a method for performing curved surface diffusion welding using a pressurized assembly according to the present invention;

[0035] Serial number description:

[0036] 1. Dot matrix pressure piece; 11. Driving base; 12. Mounting position; 13. Pressure rod; 2. Curved contact piece; 21. Pressure plate base; 22. Movable pressure plate assembly; 221. First-level pressure plate; 222. Second-level pressure plate; 223. Third-level pressure plate; 23. Solder mask;

[0037] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] The terms "first," "second," and "third" in this application are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of such features. In the description of this application, "multiple" means at least two, for example, two, three, etc., unless otherwise specifically defined. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship, movement, etc. between the components under a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications also change accordingly. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products, or devices.

[0040] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] Diffusion welding is a solid-state joining process in which the two workpieces to be welded are compacted together and heated in a vacuum or protective gas environment. This causes plastic deformation at the minute protrusions on the surfaces of the two workpieces, achieving close contact. The workpieces are then heated and insulated to allow atoms on both sides of the contact surface to diffuse into each other, forming a metallurgical connection. Diffusion welding allows the entire interface contact position to be connected, which is extremely important for achieving high-strength internal connections between workpiece plates. Furthermore, the base material undergoes no phase change from melting to solidification during welding, so the properties of the base material itself do not change significantly, and the strength of the welded joint approaches or even reaches that of the base material. Diffusion welding is suitable for joining most metals, some non-metallic materials such as ceramics, glass, and silicon, as well as dissimilar metals and even metal-nonmetal connections.

[0042] Existing diffusion welding equipment is shown in Figure 1 and includes a pressurization system, a vacuum system, a heating element, and a control system. The heating element is mainly composed of an electric heating element arranged on the inner wall of the welding temperature zone. During welding, the workpiece is heated by radiating heat from the heating element. The pressurization system consists of a hydraulic booster system, a hydraulic cylinder, a connecting rod, and a solder mask pressure plate. When pressure is applied, the booster system drives the hydraulic connecting rod to move, and applies pressure to the workpiece to be welded through the upper and lower pressure plates to ensure effective contact between the welding surfaces of the workpiece. Under the combined action of the temperature load, the metal atoms on both sides of the welding interface diffuse with each other, thereby forming a strong weld joint. The vacuum system is mainly responsible for extracting gaseous substances in the welding zone to prevent oxidation reactions between the workpiece to be welded and the gaseous substances at high temperatures. The control system ensures that the welding equipment adjusts and controls the welding process parameters such as temperature, pressure, vacuum degree, and holding time according to the steps set by the program.

[0043] As shown in Figure 2, current conventional diffusion welding equipment is only suitable for diffusion welding of planar workpieces. By applying a small number of pressure points to a single solder resist platen, this method can only apply uniform compressive stress to the welded workpiece. Furthermore, heating the workpiece to be welded using a sidewall heating assembly does not effectively heat the upper and lower surfaces of the workpiece. Therefore, current diffusion welding equipment and methods cannot meet the requirements for zoned pressure regulation under non-uniform temperature conditions and cannot be applied to curved workpieces.

[0044] In the side wall heating method used by conventional diffusion welding equipment, the temperature distribution of the workpiece cross section is shown in Figure 3. During diffusion welding, the workpiece to be welded is heated by the heating element on the side wall of the temperature zone through thermal radiation. The heat is transferred from the surface of the workpiece to the inside of the workpiece through heat conduction. Due to the thermal resistance of the workpiece material, the temperature distribution of the workpiece to be welded cannot be uniform. The surface temperature is the highest and the center area is the lowest. The diffusion welding bonding strength is determined by many factors such as temperature and compressive stress value. The model shown in formula (1) can be constructed by combining various influencing factors: Q local =f(Tlocal ,σ local ,t s ,M,F local ) (1)

[0045] Among them, Q local Indicates the local diffusion welding strength of the workpiece, T local Represents the local temperature of the workpiece, σ local Indicates the local stress value of the workpiece, t s Indicates the workpiece insulation time, M indicates the parameter related to the material type, F local Indicates the roughness of a local position on the material surface. For each position of the same workpiece, t s , M, F local The difference can be ignored and fitted as a constant term. Then, for a certain workpiece, the local diffusion welding strength at each position has the following relationship: Q local =f(T local ,σ local ) (2)

[0046] Regarding the influence of diffusion welding temperature, there are the following models:

[0047] D=D0exp(-E / RT local ) (3)

[0048] Where D represents the diffusion coefficient. A larger value indicates stronger diffusion of metal atoms and better diffusion welding strength, thus representing the diffusion welding strength. D0 is a constant coefficient, E represents the volume diffusion activation energy, a constant related to the material type, and R represents the gas constant.

[0049] Regarding the influence of diffusion welding compressive stress, according to the power law of stress-strain in the creep process of diffusion welding, there is the following model:

[0050] Where ε represents the strain value during the diffusion welding process. A larger value indicates a greater diffusion welding strength and can be used to characterize the diffusion welding strength. E represents the Young's modulus of the material, A0 is a constant coefficient, and m is a constant exponent.

[0051] Therefore, formula (2) can be written as follows:

[0052] Among them, C0 represents the normalization coefficient, which is a constant, and n is the normalization index. From formula (5), it can be seen that during diffusion welding, T local , σ local There is a positive correlation between the strength of the diffusion welding joint and the increase of welding temperature and compressive stress can achieve better welding results.

[0053] It can be seen from the model of formula (5) that for the problem of uneven temperature distribution of the workpiece, coordinated control is required through pressure load partition adjustment. The relatively minimum pressure load should be applied to the peripheral area of ​​the workpiece to be welded, and the relatively maximum pressure load should be applied to the central area of ​​the workpiece to be welded. The other areas should be applied with corresponding pressure loads according to formula (5) according to the change of temperature.

[0054] In response to the aforementioned problem that existing diffusion welding equipment cannot be applied to curved workpieces, this application proposes a pressurizing assembly that applies pressure through a dot matrix and independently controls the pressure applied at the dot matrix pressure positions, thereby meeting the welding pressure requirements of workpieces with curved and irregular surfaces. Figures 4 and 5 show an embodiment of a pressurizing assembly for diffusion welding of curved workpieces. The pressurizing assembly is used to pressurize the curved workpiece after being connected to a pressurizing system. The pressurizing assembly includes:

[0055] A lattice pressurizing member 1 includes a driving base 11 and a plurality of pressurizing rods 13. The driving base 11 is provided with a plurality of mounting positions 12 distributed in a lattice, one pressurizing rod 13 is mounted on each mounting position 12, and all pressurizing rods 13 are parallel to each other. The driving base 11 independently drives the pressurizing rod 13 mounted on each mounting position 12 to independently pressurize a portion of the curved workpiece.

[0056] Specifically, the driving method of the driving base 11 can be hydraulic drive, pneumatic drive and mechanical propulsion. In terms of driving power, since the pressurizing component is connected to the pressurizing system, the lattice pressurizing member 1 can obtain power from the current and voltage of the pressurizing system. The driving base 11 is provided with mounting positions 12 distributed in a lattice. In this application, the "lattice" distribution refers to a distribution structure formed by an array in a specific direction. For example, in this embodiment, with a certain mounting position 12 as the "starting point", a number of identical mounting positions 12 are set at the same intervals in the horizontal and vertical directions to form a lattice surface with length and width. The pressurizing rod 13 can include any rod that can be extended or shortened in the axial direction by the driving action. The pressurizing rod 13 is installed at the mounting position 12 of the driving base 11. Accordingly, according to the lattice distribution structure of the mounting position 12, the ends of all the pressurizing rods 13 also form a lattice surface, and the compressive stress acting on each area of ​​the curved workpiece can be applied and adjusted by changing the length of each pressurizing rod 13 to adapt to different curved surface structures.

[0057] Optionally, the dot matrix distribution outline of the installation position 12 is a regular polygon.

[0058] The formation of a regular polygon has been illustrated in the aforementioned embodiment and will not be repeated here. The regular polygon can be selected as needed, and by changing the side length of the regular polygon (i.e., by adjusting the number of mounting positions 12 spaced in the same direction) and the number of sides of the regular polygon, the lattice pressure member 1 can be made more adaptable to curved workpieces of different morphological structures. In other words, as long as the area of ​​the lattice surface is larger than the minimum enclosing area of ​​the curved workpiece (the minimum enclosing area can be expressed in the form of a circle or a regular polygon), it can be pressure-welded, thereby improving the utilization rate of each pressure rod 13 in the lattice pressure member 1.

[0059] Demonstration Example 1: See Figure 4 or Figure 5. The curved workpiece is a workpiece to be welded with a wavy longitudinal cross-section, and the welding requires retaining the longitudinal cross-section shape. The simulated shape data is input through the pressurizing system, and the control signal is output to the lattice pressurizing member 1 according to the set program, so that each pressurizing rod 13 in the lattice pressurizing member 1 is extended or shortened according to the instruction data in the signal, forming a wavy shape consistent with the longitudinal cross-section of the workpiece to be welded and applying pressure to each curved surface part of the workpiece to be welded, applying appropriate compressive stress in each area.

[0060] It should be noted that the specific parameters of the lattice surface formed by the lattice pressure piece 1 are not given in this demonstration example, and it is intended to include all the lattice surface parameter setting ranges that can achieve the curved surface pressure effect. It can be understood that the specific parameters of the lattice surface formed by the lattice pressure piece 1 include at least: the spacing between adjacent mounting positions 12, the number of mounting positions 12, the degree of density change (which can be characterized by the ratio of the number of mounting positions 12 in the outermost circle to the number of mounting positions 12 in the innermost circle), the straight (radial) diameter of the pressure rod 13, the number of pressure rods 13, the retractable range, etc.; using the aforementioned spacing parameters of adjacent mounting positions 12 as an example, in the lattice surface control group of the same area, if the number of mounting positions 12 is not restricted, the smaller the spacing between adjacent mounting positions 12, the smaller the lattice surface. The more mounting positions 12 a surface has, the more or denser the pressure rods 13 that can be installed. When pressure is applied to the workpiece to be welded, the larger the effective contact area and the action area with the curved surface are, the better the pressure effect is. That is, adjusting the spacing parameters and other related parameters of adjacent mounting positions 12 can improve the overall action accuracy of the pressure component to varying degrees, which is more conducive to the realization of the pressure effect of the pressure component of this application. However, they are all further improvements to the effects achieved in the aforementioned embodiments, and the technical feature improvements proposed on this basis should be included in the scope of protection required by this application.

[0061] In combination with the above technical solutions and explanations, the pressurizing component of the present application forms a lattice pressurizing part 1 by setting a number of mounting positions 12 distributed in a lattice on the same surface on a driving base 11 and installing a pressurizing rod 13 on each mounting position 12, wherein the lattice pressurizing part 1 is controlled by a pressurizing system, and the pressurizing system independently controls the pressurizing rod 13 on each mounting position 12 through the driving base 11 without interfering with each other, so that when pressure welding a curved workpiece, the applied stress of each area of ​​the pressurizing component can be adjusted according to the actual contour of the curved workpiece. Compared with the existing planar equivalent pressurizing component, it effectively realizes the adaptive application of compressive stress according to the curvature change of the curved workpiece.

[0062] As an embodiment, based on the aforementioned embodiment, the pressurizing assembly further includes a curved surface contact member 2, and the curved surface contact member 2 includes a pressure plate base 21 fixedly connected to the free end of each pressurizing rod 13, and each pressure plate base 21 is provided with a multi-stage movable pressure plate combination 22 at one end away from the pressurizing rod 13, and the movable pressure plate combination 22 includes a plurality of layered movable pressure plates, and each pressure plate base 21 is movably connected to the adjacent movable pressure plate and each movable pressure plate through electromagnetic adsorption and mutually cooperating joint sockets.

[0063] Specifically, the ends of each pressure rod 13 are connected to a pressure plate base 21 and a movable pressure plate assembly 22 in sequence from the proximal end to the distal end, wherein the end of the pressure rod 13 is tightly connected to the pressure plate base 21, and the pressure plate base 21 is movably connected to the movable pressure plate assembly 22. The movable connection method can be an electromagnetic adsorption connection, which is achieved by providing an energized electromagnetic induction coil inside the pressure plate base 21. The pressure plate base 21 and each movable pressure plate are provided with a joint socket on the side close to the workpiece to be welded. A movable pressure plate is electromagnetically adsorbed in each joint socket and can be movable in the joint socket.

[0064] In particular, the electromagnetic adsorption method of the movable pressing plate assembly 22 is also affected by the material of the movable pressing plate. The movable pressing plate can be made of magnetic metal.

[0065] Regarding the glenoid fossa in this embodiment, the following two further embodiments can be provided:

[0066] Optionally, the joint socket is a cylindrical concave cavity, which is arranged on the side of each pressure plate base 21 away from the pressure rod 13 and on the side of each movable pressure plate close to the next level movable pressure plate. Each movable pressure plate cooperates with the cylindrical concave cavity and moves in the cylindrical concave cavity under the action of external force. The number of movable pressure plates at each level increases step by step along the direction from the pressure plate base 21 to the curved workpiece.

[0067] Demonstration example 2: See Figure 6. The articular cavity in this embodiment is a cylindrical concave cavity, which is respectively arranged on the pressure plate base 21, the first-level pressure plate 221, the second-level pressure plate 222 and the third-level pressure plate 223, and the number of the first-level pressure plate 221, the second-level pressure plate 222 and the third-level pressure plate 223 increases step by step (such as the first-level pressure plate 221 is 1, the second-level pressure plate 222 is 2 and the third-level pressure plate 223 is 4) to increase the overall freedom of movement of the movable pressure plate combination 22. The third-level pressure plate 223 (or the final pressure plate) can no longer be provided with a articular cavity and form an end with a smaller width, thereby increasing the fit with the curved surface of the workpiece to be welded.

[0068] It can be understood that in the embodiment where the joint socket is a cylindrical concave cavity, the activity change of the pressure plate is limited to a two-dimensional plane, that is, the plane formed by the direction indicated by the double-headed arrow in FIG5 . This embodiment is relatively limited in the curved surface conditions that can be handled in the three-dimensional space. Since there are also irregular and complex curved surfaces to be welded,

[0069] Further optionally, the joint socket is a spherical cavity, which is arranged on the side of each pressure plate base 21 away from the pressure rod 13 and on the side of each movable pressure plate close to the next level movable pressure plate. Each movable pressure plate cooperates with the spherical cavity and moves in the spherical cavity under the action of external force. The number of movable pressure plates at each level increases step by step along the direction from the pressure plate base 21 to the curved workpiece.

[0070] Demonstration Example 3: Referring to Figure 7, the joint socket in this embodiment is a spherical cavity, and its setting method can refer to Demonstration Example 2. However, in terms of freedom of movement, the spherical cavity can enable the movable pressure plate to move in countless directions compared to the cylindrical cavity. In other words, it can better fit the irregular curved surface in the three-dimensional space, and the fit with the curved surface can be significantly improved.

[0071] It should be noted that Demonstration Examples 2 and 3 are provided for illustrative purposes only and are not intended to limit specific features. For example, the movable platen assembly 22 may include three or more stages, and the number of stages can be adjusted based on the curvature of the workpiece. For example, when the workpiece surface is less curved, the number of stages can be reduced. For more curved workpieces, the number of stages can be increased to accommodate the highly curved surface.

[0072] Optionally, a solder resist 23 is provided on the movable platen assembly 22 in the aforementioned embodiment that contacts the curved workpiece. The solder resist 23 can be made of any material that resists diffusion welding, including high-strength graphite. Its purpose is to prevent molecular diffusion welding between the movable platen and the curved surface.

[0073] Based on the above explanations, this embodiment adds a curved contact piece 2 arranged at the end of the pressure rod 13, and further uses the joint socket form and electromagnetic adsorption method to make the end pressure plate and the curved surface (including irregular complex curved surface) form a better curvature fit, thereby increasing the effective force-bearing area on the curved surface of the pressure rod 13, and forming a good compressive stress distribution, which is conducive to the forming effect of diffusion welding.

[0074] As an embodiment, based on the above embodiment, the pressurizing assembly further includes an induction heating element, which is disposed near the free end of each pressurizing rod 13 to heat the curved surface of the workpiece in a zoned manner.

[0075] Specifically, the induction heating element can be realized by the electromagnetic induction coil in the aforementioned embodiment (arranged inside the pressure plate base 21, partially not shown in the drawings), and electrically connected to the pressurizing system through the wiring channel in each pressurizing rod 13, and the voltage and current in the electromagnetic induction coil are controlled by the pressurizing system; by adjusting the voltage and current in the electromagnetic induction coil and selecting coil materials with different resistivities, the induction heating effect is formed.

[0076] In this embodiment, by arranging an induction heating element at the end of each pressurizing rod 13, a special heating area corresponding to the lattice surface and corresponding to the curved surface of the workpiece to be welded is formed, and each induction heating element can also be independently controlled, which has higher collaborative efficiency in adjusting the regional heating temperature; when the uniform heating conditions cannot reach the thermal stress of the curved surface (including irregular and complex curved surfaces), the induction heating element can be started and the regional heating temperature can be adjusted according to the data input of the pressurizing system.

[0077] It should be noted that the control of the lattice pressurizing element 1 and the induction heating element according to the pressurizing system mentioned in the above embodiment is only used for explanation as a control principle or logic, and is not limited as a specific technical feature, and does not belong to the main application point of this application; on the other hand, the signal control of the pressurizing system belongs to the existing technology and will not be repeated here.

[0078] In particular, the pressurizing components in any of the aforementioned embodiments are not limited to being used alone, and can be used in the same device in groups, pairs, or multiple combinations as needed.

[0079] The present application also provides a curved surface workpiece diffusion welding device, which includes a pressurizing system, the output of which is connected to the pressurizing component in any of the above-mentioned embodiments to drive the pressurizing component to pressurize the workpiece to be welded.

[0080] As an embodiment, the diffusion welding equipment for curved workpieces includes a pressurization system, a heating system, a vacuum system and a control system as shown in Figure 2. The control system is used to integrate and control the pressurization system, the heating system and the vacuum system. The control system includes a control platform that directly faces the operator and receives the operator's data output and control operations.

[0081] The present application also provides a method for diffusion welding a curved workpiece. The method is applied to a curved workpiece diffusion welding device. The curved workpiece diffusion welding device includes a pressurizing system. The output of the pressurizing system is connected to a pressurizing assembly as in any of the previous embodiments to drive the pressurizing assembly to pressurize the workpiece to be welded. Referring to FIG8 , the method includes:

[0082] S1, determining the maximum thermal stress value ΔS of the workpiece to be welded under uniform heating conditions max Whether it exceeds the preset allowable limit ΔS lim ;

[0083] The uniform heating conditions include conventional side wall heating and upper and lower wall uniform heating using the induction heating element of the pressurizing assembly in the aforementioned embodiment. The upper and lower uniform heating method achieves uniform heat generation and radiation by passing the same current through the electromagnetic induction coils provided at the ends of each pressurizing rod. Maximum thermal stress value ΔS max The temperature field distribution on the workpiece to be welded is obtained by a temperature monitoring device such as an infrared sensor device and then determined by mathematical calculation or experiment. Similarly, the preset allowable limit ΔS lim An allowable limit value that can meet the minimum pressure welding conditions can be determined through experiments or theoretical analysis and calculation.

[0084] Specifically, step S1 includes:

[0085] S11, obtaining the temperature field distribution of the workpiece to be welded under the side wall heating condition;

[0086] S12, based on the temperature field distribution under the side wall heating condition, determine the maximum thermal stress value ΔS of the workpiece to be welded max Whether it exceeds the preset allowable limit ΔS lim ;

[0087] S13a, if not, determining the applied compressive stress in each area of ​​the workpiece to be welded according to the temperature field distribution under the side wall heating condition;

[0088] or:

[0089] S13b, if yes, start the induction heating element of the pressurizing assembly to perform uniform heating and obtain the temperature field distribution of the workpiece to be welded under the conditions of side wall heating and upper and lower wall heating;

[0090] S14, determining the applied compressive stress in each region of the workpiece to be welded according to the temperature field distribution under the conditions of side wall heating and upper and lower wall heating;

[0091] It should be noted that in the judgment process of step S1, no matter under which heating conditions, as long as the applied compressive stress of each area of ​​the workpiece to be welded is determined according to the temperature field distribution under the side wall heating conditions or the temperature field distribution under the side wall heating and upper and lower wall heating conditions, the following steps S5 and S6 can be directly executed for pressure welding.

[0092] In a specific embodiment of step S1, the temperature field distribution is a set of temperature data at various locations on the workpiece to be welded obtained by the temperature monitoring device described in the previous explanation, including specific temperature values ​​and other alternative values ​​that can represent the temperature values. The applied compressive stress of each area of ​​the workpiece to be welded is determined based on the temperature field distribution (the set of temperature data at various locations on the workpiece to be welded) by the aforementioned formula (5),

[0093] Among them, Q local Indicates the local diffusion welding strength of the workpiece, T local Represents the local temperature of the workpiece, σ local It represents the local stress value of the workpiece, C0 represents the normalization coefficient, which is a constant, n is the normalization exponent, E represents the volume diffusion activation energy, a constant related to the material type, and R represents the gas constant.

[0094] Through this model, we can understand that the local temperature of the workpiece T local and the workpiece local stress value σ local There is a coupling relationship between them, which can be obtained by fitting the experimental data, and then obtaining the specific functional relationship according to the model of formula (5).

[0095] When the uniform heating condition cannot meet the preset judgment condition, it means that due to the large variation in the curved surface of the workpiece to be welded and the complex structure, the uniform heating condition cannot make the thermal stress value at each location of the workpiece to be welded meet the minimum requirement for pressure welding. Therefore, after step S1, the following steps are further performed:

[0096] S2, if yes, heating is performed according to the preset zone heating temperature, and the maximum thermal stress value ΔS of the workpiece to be welded under the zone heating condition is used. max Whether it exceeds the preset allowable limit ΔS lim As iterative conditions, determining the upper and lower wall partition heating temperatures and the temperature distribution field of the workpiece to be welded;

[0097] S4, determining the required applied stress for each area of ​​the workpiece to be welded based on the determined upper and lower wall zone heating temperatures and the first temperature distribution field of the workpiece to be welded;

[0098] Similarly, the required applied stress in each area of ​​the workpiece to be welded is also determined by the above-mentioned formula (5) model.

[0099] Steps S2 to S5 are specific control execution steps for regional heating using the pressurizing assembly in the aforementioned embodiment of the present application. They mainly rely on the "lattice" setting of the induction heating element on each pressurizing rod and form independent control to achieve regional heating. This heating method can improve the heating efficiency and effect of each area of ​​the curved surface (including irregular and complex curved surfaces), and help each area of ​​the workpiece to be welded meet the thermal stress requirements required for pressure welding.

[0100] S5, selecting and installing a movable pressing plate assembly according to the determined required applied stress and the curved surface condition of the workpiece to be welded;

[0101] The selection and installation of the movable pressure plate assembly is mainly for making adaptive adjustments according to the actual workpiece to be welded. The specific methods and effects have been described in the above-mentioned embodiments and will not be repeated here.

[0102] S6, using the lattice pressurizing element and the induction heating element of the pressurizing assembly to independently pressurize and heat the partitions of the workpiece to be welded to perform pressure welding.

[0103] In the above embodiment, after step S1, the following steps are further included:

[0104] If not, the partitions of the workpiece to be welded are independently pressurized and heated by the lattice pressurizing element and the induction heating element of the pressurizing assembly to perform pressure welding.

[0105] The surface workpiece diffusion welding method of the present application relies on the pressurizing component in the aforementioned embodiment to achieve the coordination of heating and pressurizing during the diffusion welding process, thereby improving the pressure welding efficiency and effect for curved surfaces (including irregular and complex curved surfaces).

[0106] The above detailed description of the specific implementation methods of the application is intended only as an example, and the present application is not limited to the specific implementation methods described above. For those skilled in the art, any equivalent modifications or substitutions made to the application are also within the scope of the present application. Therefore, equivalent changes, modifications, and improvements made without departing from the spirit and scope of the present application should be included within the scope of the present application.

Claims

1. A pressurizing assembly for diffusion welding of a curved workpiece, the pressurizing assembly being used to pressurize the curved workpiece after being connected to a pressurizing system, wherein, The pressurizing assembly includes: A dot matrix pressurizing member, which includes a driving base and a plurality of pressurizing rods. The driving base is provided with a plurality of mounting positions distributed in a dot matrix. One pressurizing rod is installed in one mounting position and all the pressurizing rods are parallel to each other. The driving base independently drives the pressurizing rod installed in each mounting position to independently pressurize a local area of the curved workpiece.

2. The pressurizing assembly according to claim 1, wherein, The pressurizing assembly further includes an induction heating member, which is arranged near the free end of each pressurizing rod to heat the curved surface area of the curved workpiece.

3. The pressurizing assembly according to claim 2, wherein, The pressurizing assembly further includes a curved surface contact member, which includes a pressing plate base fixedly connected to the free end of each pressurizing rod. At one end of each pressing plate base away from the pressurizing rod, there is a multi-stage movable pressing plate combination. The movable pressing plate combination includes a plurality of movable pressing plates arranged in layers. Each pressing plate base is movably connected to the adjacent movable pressing plate and between the movable pressing plates through electromagnetic adsorption and matching socket joints.

4. The pressurizing assembly according to claim 3, wherein, The socket joint is a cylindrical surface concave cavity, which is arranged on one side of each pressing plate base away from the pressurizing rod and on one side of each movable pressing plate close to the next-stage movable pressing plate. Each movable pressing plate cooperates with the cylindrical surface concave cavity and moves in the cylindrical surface concave cavity under the action of an external force. The number of movable pressing plates at each stage increases gradually along the direction from the pressing plate base to the curved workpiece.

5. The pressurizing assembly according to claim 3, wherein, The socket joint is a spherical surface concave cavity, which is arranged on one side of each pressing plate base away from the pressurizing rod and on one side of each movable pressing plate close to the next-stage movable pressing plate. Each movable pressing plate cooperates with the spherical surface concave cavity and moves in the spherical surface concave cavity under the action of an external force. The number of movable pressing plates at each stage increases gradually along the direction from the pressing plate base to the curved workpiece.

6. The pressurizing assembly according to claim 4 or 5, wherein, A soldering resistance plate is arranged on the movable pressing plate in contact with the curved workpiece of the movable pressing plate combination.

7. The pressurizing assembly according to claim 3, wherein, The driving base drives each pressurizing rod by hydraulic pressure, air pressure or mechanical propulsion.

8. The pressurizing assembly according to claim 1, wherein, The dot matrix distribution contour of the mounting position is a regular polygon.

9. A diffusion welding device for a curved workpiece, wherein, The diffusion welding equipment for the curved workpiece includes a pressurizing system, and the output of the pressurizing system is connected to the pressurizing assembly according to any one of claims 1 to 8 to drive the pressurizing assembly to pressurize the workpiece to be welded.

10. A diffusion welding method for a curved workpiece, the diffusion welding method for the curved workpiece being applied to a diffusion welding device for a curved workpiece, the diffusion welding device for the curved workpiece including a pressurizing system and a pressurizing component as described in any one of claims 2 to 8, an output of the pressurizing system being connected to the pressurizing component, wherein, The diffusion welding method for the curved workpiece includes: Determine the maximum thermal stress value ΔS of the workpiece to be welded under uniform heating conditions max whether it exceeds the preset allowable limit value ΔS lim ; If so, heat according to the preset partition heating temperature, and use the maximum thermal stress value ΔS of the workpiece to be welded under the partition heating condition max whether it exceeds the preset allowable limit value ΔS lim as the iteration condition to determine the partition heating temperature of the upper and lower wall surfaces and the temperature distribution field of the workpiece to be welded; According to the determined heating temperature of the upper and lower wall surface areas and the first temperature distribution field of the workpiece to be welded, determine the required applied stress for each area of the workpiece to be welded. According to the determined required applied stress and the curved surface condition of the workpiece to be welded, select a matching dot matrix pressurizing member. Through the dot matrix pressurizing member and the induction heating member of the pressurizing assembly, independently pressurize and heat the partition of the workpiece to be welded for pressure welding.

11. The diffusion welding method for a curved workpiece according to claim 10, wherein, The step of judging whether the maximum thermal stress value ΔS of the workpiece to be welded under uniform heating conditions max exceeds a preset allowable limit value ΔS lim includes uniformly heating the side wall surface of the workpiece to be welded and uniformly heating the upper and lower wall surfaces of the workpiece to be welded.

12. The diffusion welding method for a curved workpiece according to claim 10, wherein, In the step of determining the required applied stress for each region of the workpiece to be welded according to the determined heating temperature of the upper and lower wall surface partitions and the first temperature distribution field of the workpiece to be welded, the required applied stress for each region of the workpiece to be welded is determined by the following model; Among them, Q local represents the local diffusion welding strength of the workpiece, T local represents the local temperature of the workpiece, σ local represents the local stress value of the workpiece, C0 represents the normalization coefficient, which is a constant, n is the normalization exponent, E represents the activation energy of volume diffusion, which is a constant related to the material type, and R represents the gas constant.

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