A high-precision additive and subtractive manufacturing method of hyperbolic cold plate

Abstract

In view to the problems of low yield, high manufacturing cost, insufficient residual stress control and poor machining precision of integrated conformal cold plate in the forming process, the application provides a high-precision hyperbolic cold plate additive and subtractive manufacturing method, which introduces process residual stress monitoring, heat treatment decision, redundant reference design, database-based process optimization mechanism and auxiliary reference establishment of three-dimensional deformation measurement combined with compensation pad tooling in the cold plate forming process, and realizes high-precision forming and high stability of the hyperbolic cold plate.

Description

Technical Field

[0001] This invention belongs to the field of manufacturing and precision machining, and specifically relates to a high-precision method for manufacturing hyperbolic cold-rolled steel plates using additive and subtractive materials. Background Technology

[0002] Conformal antenna systems are a typical type of complex electromechanical coupling system. These systems not only need to meet electromagnetic performance requirements but also need to consider constraints such as structural strength, heat dissipation capacity, and installation compatibility. The cold plate, as a key load-bearing and heat dissipation component in the antenna system, provides a stable heat dissipation channel for the antenna elements and related electronic devices, thereby ensuring long-term reliable system operation. Unlike traditional planar cold plates, conformal antennas are often arranged on complex curved surfaces. The cold plate must transition from a planar structure to a curved or even hyperboloidal shape to achieve a close fit with the external shape. Through this conformal design, the cold plate can more directly conduct the heat generated by the devices to the external environment, thereby improving heat dissipation efficiency. However, this change in geometry significantly increases the design and manufacturing difficulty of the cold plate.

[0003] Traditional heat dissipation cold plates are typically manufactured using welding and machining methods, suitable for structures with relatively simple internal flow channels. As a core heat dissipation and load-bearing component in conformal antenna systems, the cold plate must not only maintain structural strength but also achieve efficient heat dissipation for high-power devices and electromagnetic modules. Compared to traditional planar cold plates, conformal cold plates can be arranged close to the curved shape of the antenna or electronic module, making the heat transfer path between the heat source and the heat dissipation circuit more direct and efficient, thus significantly improving heat dissipation performance and reducing interfacial thermal resistance—a key advantage of conformal design. However, as antenna regions gradually transition from planar to complex curved or even hyperboloid shapes, the overall design and manufacturing difficulty of the cold plate increases significantly. On the one hand, the large changes in curvature require the cold plate to precisely fit irregular curved surfaces; on the other hand, the internal cooling channels must be arranged in three dimensions within a limited space, not only meeting heat dissipation efficiency requirements but also ensuring coupling and matching with the curved surface. This dual constraint greatly increases the complexity of manufacturing. Traditional welding processes cannot guarantee the requirements of curved cold plates in terms of shape accuracy, flow channel continuity, and overall strength, thus having significant limitations in the manufacturing of conformal cold plates.

[0004] Additive manufacturing technology offers a new solution for integrated heat dissipation and load-bearing cold plates. This process enables the direct fabrication of complex flow channels and irregular curved surfaces during the forming process, overcoming the limitations of traditional subtractive manufacturing and welding processes. With increasing heat dissipation demands, the internal flow channel design of cold plates has evolved from simple straight-through structures to multi-branch, multi-loop, and variable cross-section structures. Topology optimization design methods are even used to improve overall structural stability and load-bearing capacity while meeting heat dissipation efficiency requirements. This complex three-dimensional flow channel arrangement is impossible to achieve with traditional processes and can only be accomplished through additive manufacturing. Meanwhile, since conformal antenna systems are typical electromechanically coupled complex systems, cold plates not only need to undertake heat dissipation tasks but also need to meet multiple constraints related to electromagnetic characteristics, mechanical strength, and assembly space. To adapt to the antenna electromagnetic unit and overall structural layout, the exterior of the cold plate often requires various features, such as mounting holes, positioning bosses, connecting surfaces, and fastening areas. These external features are directly related to electromagnetic performance, structural coupling, and assembly accuracy, leading to increasingly complex cold plate shapes and significantly higher requirements for processing and forming precision.

[0005] Furthermore, the melt-cooling deposition process used in 3D printing inevitably generates significant residual stress, which can easily lead to deformation of the cold-plate during forming and subsequent processing. Currently, the common method to eliminate residual stress is through heat treatment annealing; however, the heat treatment and support removal processes themselves can still cause additional deformation, severely impacting the overall forming accuracy and yield of the cold-plate, resulting in high processing costs. Existing processes often suffer from low yield rates, insufficient precision, and a lack of process monitoring in practical applications, making it difficult to meet the needs of engineering applications.

[0006] In summary, the current conformal cold plate with integrated heat dissipation and load bearing still faces challenges such as low yield, high manufacturing cost, insufficient control of residual stress, and poor processing accuracy during the forming process. Therefore, it is urgent to propose a new manufacturing method that can take into account the manufacturability of complex structures, control of residual stress after heat treatment, and guarantee of processing accuracy. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a high-precision additive and subtractive manufacturing method for hyperboloid cold-rolled steel plates. This method achieves high-precision forming and high stability of hyperboloid cold-rolled steel plates by introducing residual stress monitoring, heat treatment decision-making, redundant benchmark design, a database-based process optimization mechanism, and auxiliary benchmark establishment using three-dimensional deformation measurement combined with compensation pad tooling. Specifically, it includes the following steps: The internal flow channels of the cold plate are arranged and designed, and the machinability of the characteristic wall thickness of the hyperbolic cold plate is evaluated. Based on the evaluation results, the local structure is modified to ensure the feasibility of molding and subsequent processing. During the process model design stage, process allowances are set, and residual stress detection areas are evenly distributed on the unsupported surface of the cold plate to reflect the overall stress distribution. The residual stress in the reserved area can be measured at least three times to meet the residual stress measurement requirements before and after heat treatment. Simultaneously, redundant finishing process reference bosses are added. During subsequent processing, the optimal reference is selected based on the redundant design to reduce reference error. After molding and removal from the machine, residual stress and cold plate surface deformation are measured in the preset detection area. After obtaining the measurement data, heat treatment is performed to eliminate residual stress generated during printing. More preferably, residual stress and deformation are measured again after heat treatment. The results of the two residual stress and deformation measurements are compared. If the residual stress and deformation measurement results have dropped to an acceptable range, the cold plate blank post-processing continues; if the preset threshold is not reached, a second heat treatment is performed until it reaches the ideal range before proceeding with the subsequent support removal operation. During heat treatment, a process database based on historical measurement data of the parts is established, linking and storing the parts' dimensions, structural features, and wall thickness parameters with heat treatment process parameters (including temperature, holding time, and cooling method). This database can be accessed during subsequent part processing, enabling standardized and parameterized selection of heat treatment processes. The database is continuously updated based on newly acquired data, allowing for the correction and iteration of the heat treatment decision model, thereby gradually improving the accuracy of predictions and decisions.

[0008] Before the blank enters the rough machining process, a three-dimensional deformation measurement is performed on the blank, and the actual deformation of the blank is obtained by fitting the measurement results. Compensation parameters are generated based on the fitting results, and a reference compensation pad matching the shape of the blank is designed. The reference compensation pad is fixed to the blank by screwing, forming an integral unit with the blank, thus serving as an auxiliary process reference for clamping and positioning. The contact surface of the reference compensation pad is a three-dimensional matching surface generated based on the three-dimensional fitting results to ensure the fitting accuracy of the compensation. Further preferably, the compensation pad is detachable after machining, without affecting the final shape and performance of the cold-rolled plate.

[0009] After clamping using the auxiliary process reference established by the reference compensation pad, the large surface is machined by rough machining; the machined large surface is used as the global machining reference for subsequent finishing steps, thereby ensuring the overall machining accuracy and stability.

[0010] The beneficial effects of this invention are as follows: 1) This invention addresses the technical challenges of complex internal and external structures, large differences in wall thickness, and uneven stress distribution in hyperbolic cold-rolled steel sheets, which lead to high molding risks. It proposes a control method combining multi-stage residual stress monitoring and process heat treatment. By real-time detection and evaluation of residual stress, combined with database-driven heat treatment decisions, it can effectively release locally accumulated high-stress areas in complex structures, significantly reducing the risk of warping, cracking, and other deformations in the cold-rolled steel sheet during support removal and subsequent finishing stages, thereby ensuring overall molding accuracy.

[0011] 2) This invention overcomes the positioning inaccuracy problem caused by the complexity of the internal and external features of hyperbolic cold plates and the difficulty in selecting conventional references by adding redundant reference bosses to the process model and performing flatness calibration before machining. This measure ensures the reference stability and machining accuracy of complex cold plates in subsequent roughing and finishing processes, and avoids the step-by-step amplification of machining errors.

[0012] 3) This invention establishes a standardized module library based on historical process data of cold-rolled steel plates. Combined with part structural parameters, dimensional characteristics, and mechanical performance requirements, it can intelligently select and match heat treatment parameters. For cold-rolled steel plates with complex structures and large dimensional ranges, this database can quickly provide suitable process solutions and iteratively optimize them as data accumulates, making the process solutions more accurate and adaptive, thus improving the controllability and repeatability of complex cold-rolled steel plate processing.

[0013] 4) The process flow of this invention has strong overall stability and is particularly suitable for special parts such as hyperboloid cold plates with fine internal flow channels and complex external curved surfaces. Through wall thickness machinability assessment, process allowance design, and stress detection area arrangement, this invention can significantly improve the first-pass yield of complex parts, reduce the scrap rate, shorten the R&D and verification cycle, and reduce reliance on manual experience. Attached Figure Description

[0014] Figure 1 This is a flowchart of the method of the present invention.

[0015] Figure 2 This is a back view of the hyperbolic cold plate model.

[0016] Figure 3 This is a front view of the hyperbolic cold plate model.

[0017] Figure 4 This is a schematic diagram to aid in the installation of the tooling.

[0018] Among them, 1-hyperbolic cold plate, 2-process reference boss, 3-redundant process reference boss, 4-residual stress detection boss, 5-hyperbolic outer surface of cold plate blank, and 6-reference compensation pad. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0020] like Figure 1 As shown, this embodiment uses a full-process residual stress measurement method for process control in the absence of a heat treatment process database. Specifically, it includes the following steps: First, the internal flow channel layout of the hyperbolic cold plate is completed according to the design requirements, and the machinability of the wall thickness is evaluated. Local structures are then modified, followed by process model design. During the process model design stage, such as... Figure 2 and Figure 3 As shown, process allowances are set on the surface of the blank of the hyperbolic cold plate 1, and process reference bosses 2, redundant process reference bosses 3, and residual stress detection bosses 4 are added at the four corners, the middle of the four sides, and the residual stress detection area of ​​the cold plate. The hyperbolic outer surface of the cold plate blank is marked as 5. In the additive manufacturing process, a layer-by-layer forming method of melt-cooling is adopted. After forming, the residual stress detection bosses 4 are measured to obtain the overall residual stress and deformation distribution of the cold plate. Based on the measurement results, it is decided whether to perform heat treatment. Preferably, annealing heat treatment is adopted, and residual stress is eliminated by setting the temperature and holding time. After heat treatment, the residual stress is measured again, and the results before and after are compared. If the residual stress is still large, or there is abnormal stress concentration in some areas, a second heat treatment is preferably performed to further reduce the residual stress. In this way, the residual stress can still be effectively controlled by repeated detection and decision-making even without establishing a database. Subsequently, support removal and overall deformation measurement are performed. The actual deformation of the cold plate blank is fitted based on the three-dimensional scanning results. Preferably, as shown in the figure... Figure 4 As shown, a reference compensation pad 6 is designed and connected to the hyperbolic cold plate 1 via screws to form a stable auxiliary process reference. The compensation pad provides reliable support during clamping, facilitating alignment during large-area machining and establishing a global machining reference, thereby ensuring the accuracy of subsequent roughing and finishing. Finally, through roughing and finishing steps, the high-precision forming of the hyperbolic cold plate is completed, resulting in a conformal antenna cold plate with complex internal flow channels that integrates heat dissipation and load bearing. Example

[0021] With a heat treatment process database established, a database-based heat treatment decision-making and local residual stress verification method is adopted for process control. Specifically, the following steps are included: like Figure 1As shown, in this embodiment, with a pre-established heat treatment process database, preferred heat treatment parameters can be directly selected based on the database to improve process efficiency. First, design input and model design are completed, followed by process model design. In this stage, as... Figure 2 and Figure 3 As shown, process reference bosses 2, redundant process reference bosses 3, and residual stress detection bosses 4 are set on the blank shape of the hyperbolic cold plate 1. After the blank is formed, there is no need to perform global residual stress measurement. Instead, appropriate heat treatment parameters, such as heating temperature, heating rate, and holding time, are directly selected based on database experience. At the same time, local verification is performed only at some residual stress detection bosses 4 to confirm the applicability of the parameters selected in the database. Since the database has been accumulated and iteratively optimized through a large amount of previous process data, the optimized parameters can ensure that a good stress relief effect can be achieved in one heat treatment, thereby avoiding the need for a second heat treatment step. This not only shortens the processing cycle but also reduces manufacturing costs. After support removal and overall deformation measurement, as shown... Figure 4 As shown, the deformation of the cold-rolled steel blank is evaluated using a 3D scanning method, and a datum compensation pad 6 is designed based on the results. The compensation pad is fixed to the cold-rolled steel blank by screws and serves as an auxiliary process datum, thereby improving clamping stability and datum accuracy. Subsequently, roughing and finishing are performed. The redundant process datum boss 3 is used to select the optimal machining datum after scanning confirmation, avoiding error accumulation caused by deformation of a single datum and further improving machining accuracy. Through this embodiment, heat treatment parameters can be quickly determined with database support, avoiding secondary heat treatment, improving production efficiency, and significantly enhancing process stability and cold-rolled steel blank yield through the cooperation of redundant datums and compensation pads.

[0022] This invention is not limited to the specific embodiments described above, and various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made to the above embodiments based on the technical essence of this invention should be included within the scope of protection of this invention.

Claims

1. A method for manufacturing high-precision hyperbolic cold-rolled steel plates using additive and subtractive materials, characterized in that: Includes the following steps: The internal flow channels of the cold plate are arranged and designed, and the machinability of the characteristic wall thickness of the cold plate is evaluated. Based on the evaluation results, local structures are modified. During the model design stage, process allowances are set, and residual stress detection areas are evenly distributed on the surface of the unsupported areas of the cold plate. Simultaneously, process reference bosses, redundant process reference bosses, and residual stress detection bosses are added at the four corners, the middle of the four sides, and the residual stress detection areas of the cold plate, respectively. The heat dissipation-load-bearing integrated conformal cold plate is formed using additive manufacturing. After the cold plate is formed and removed from the machine, residual stress and deformation are measured in the residual stress detection areas. Based on the measurement results, heat treatment is performed to eliminate residual stress from the forming process. After heat treatment... Residual stress and deformation are measured again. If the residual stress and deformation measurement results have dropped to the preset threshold, the post-processing of the cold-rolled blank continues. If the preset threshold is not reached, a second heat treatment is performed until the threshold requirement is met. Before the cold-rolled blank enters rough machining, three-dimensional deformation measurement is performed, and the measurement results are fitted to obtain the actual deformation of the cold-rolled blank. Based on the fitting results, compensation parameters are generated, and a reference compensation pad matching the shape of the blank is designed and fixed to the cold-rolled blank by screw connection, so that the reference compensation pad and the cold-rolled blank form an integral whole, thereby serving as an auxiliary process reference for clamping and positioning the cold-rolled blank. After the cold-rolled blank is fixed and clamped, the cold-rolled blank is subjected to rough and finish machining.

2. The method according to claim 1, characterized in that: The residual stress and deformation of the residual stress detection zone shall be measured no less than 3 times.

3. The method according to claim 1, characterized in that: The reference compensation pad is fixed to the outer surface of the blank by screwing. It can be removed after processing without affecting the final shape and performance of the cold plate.

4. The method according to claim 1, characterized in that: Collect basic information on part characteristics, residual stress, and deformation measurement results before and after each heat treatment and establish a database. Call this database during subsequent part processing to achieve standardization and parameterized selection of heat treatment processes. In addition, the database also stores the correspondence between part dimensions, structural features, and wall thickness parameters and heat treatment process parameters, and make decision-making based on the database during the heat treatment process.

5. The method according to claim 4, characterized in that: The database is continuously updated based on newly collected measurement data to revise the heat treatment decision model.

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