Intercrystalline corrosion U-shaped sample preparation device and method

Abstract

The invention provides an intergranular corrosion U-shaped sample preparation device and method. The device comprises a tool cabinet, a pressure head, a power system and a mold assembly. The power system and the mold assembly are arranged on the tool cabinet, the pressure head is connected to the power system, and the pressure and stroke of the pressure head are controlled by the power system; the mold assembly is arranged below the pressure head and is matched with the pressure head above for use, positioning and fixing are carried out in the forming process of the U-shaped sample, the sample is bent into a U shape, and the accuracy of the shape and size of the sample is ensured; the special structure of the mold assembly is used for reserving a certain springback allowance in advance in the forming process of the sample, so that the two arms can be kept parallel finally after springback, and the accuracy of the shape of the U-shaped sample is ensured. By utilizing the sample preparation device, the sample processing precision is ensured, and the working efficiency is high.

Description

Technical Field

[0001] This invention belongs to the field of intergranular corrosion detection technology for metallic materials, specifically relating to an apparatus and method for preparing U-shaped samples for intergranular corrosion. Background Technology

[0002] Intergranular corrosion (IGC) refers to corrosion occurring at the grain boundaries of metallic materials. This type of corrosion typically has a severe impact on the overall structure and strength of the material. IGC testing aims to evaluate the corrosion resistance of materials under specific environments, particularly their resistance to intergranular corrosion after welding or heat treatment. It determines whether a material is prone to intergranular corrosion in specific corrosive media and optimizes material selection and processing techniques by testing the effects of different materials or treatment methods. Currently, the most common assessment method for intergranular corrosion in laboratories is physical testing, which mainly utilizes changes in physical properties to assess the degree of intergranular corrosion. Common methods include metallographic methods and bending methods. Metallographic methods involve complex sample preparation, require specialized technology and equipment, and are time-consuming, making them suitable for single-sample evaluation. The bending method involves bending the sample and observing whether cracks appear at the bend to assess the material's tendency to undergo intergranular corrosion. This method is relatively simple, easy to operate, does not require complex equipment or specialized technology, and has a short testing process, providing rapid results. It is suitable for batch testing and is more widely used in the evaluation of laboratory intergranular corrosion test samples.

[0003] However, it is difficult to ensure that the U-shaped dimensions meet the standards or specific requirements of the specimen evaluation during the process of bending the specimen into a U-shaped specimen. On the one hand, ordinary manual tools are relatively simple and have low precision. On the other hand, after bending with a fixed groove tool, the specimen will spring back into a V-shaped specimen due to the toughness of the metal material, which cannot meet the specific requirements of the standards and the specimen evaluation. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an intergranular corrosion U-shaped sample preparation device, which can obtain intergranular corrosion U-shaped samples that meet the relevant test standards or specific requirements for sample evaluation through intelligent one-press molding, and can provide more accurate evaluation during intergranular corrosion tests.

[0005] To achieve the above and other related objectives, the present invention provides an apparatus for preparing intergranular corrosion U-shaped samples, comprising:

[0006] The pressure head, one end of which is an arc-shaped end; A power system is connected to the pressure head and controls its movement. A mold assembly is disposed below the pressure head, the mold assembly comprising: A mold base, on which a first groove is provided; The first mold body and the second mold body are disposed in the first groove and are respectively connected to the mold base through elastic connectors; The first mold body and the second mold body cooperate to form a U-shaped groove and a second groove, and the second groove extends from the bottom surface of the U-shaped groove to the bottom surface of the first groove; Under the pressure of the pressure head, the first mold body and the second mold body move towards each other on the side near the top of the U-shaped groove, and move away from each other on the side near the bottom of the second groove.

[0007] According to an embodiment of the present invention, the bottom surface of the first groove is arc-shaped, and a gap is left between the bottom of the first mold body and the second mold body and the first groove.

[0008] According to an embodiment of the present invention, an arc-shaped groove is formed outward at the connection between the bottom surface of the first groove and the two sides of the first groove. The bottom of the first mold body and the second mold body respectively have protrusion structures of corresponding shapes. The protrusion structures are embedded in the arc-shaped groove to connect the mold base with the first mold body and the second mold body. Under the pressure of the pressure head, the first mold body and the second mold body rotate around the protrusion structure on them, so that the sides of the first mold body and the second mold body near the top of the U-shaped groove move towards each other, and the sides near the bottom of the second groove move away from each other.

[0009] According to an embodiment of the present invention, the top surface of the mold body is further provided with a positioning part, which is arranged along the length direction of the mold assembly, and the positioning part is symmetrically arranged on both sides of the U-shaped groove, and the sample is disposed in the positioning part.

[0010] According to an embodiment of the present invention, the positioning part includes: A positioning groove is formed on the top surface of the mold body; A sample pad is disposed in the positioning groove. The external dimensions of the sample pad match the dimensions of the positioning groove, and the internal dimensions of the sample pad match the dimensions of the sample. The sample is engaged within the sample pad.

[0011] According to an embodiment of the present invention, the elastic connector is a spring, which is disposed at both ends of the mold assembly along the width direction, and the spring on each side is arranged along the length direction of the mold assembly and symmetrically arranged about the U-shaped groove.

[0012] According to one embodiment of the present invention, one end of the spring is connected above the first mold body or the second mold body and close to the U-shaped groove, and the other end is connected below the mold base and away from the U-shaped groove.

[0013] According to an embodiment of the present invention, the power system is a hydraulic system, which includes: A hydraulic transmission device is connected to the pressure head; A control device is connected to the hydraulic transmission device to control the pressure and stroke of the pressure head.

[0014] According to an embodiment of the present invention, the hydraulic system further includes: A first workbench, wherein the mold assembly is disposed on the first workbench; A second workbench is disposed above the first workbench, and the hydraulic transmission device and the control device are disposed on the second workbench; The first worktable and the second worktable are connected by a column, and the pressure head is connected to the hydraulic transmission device and moves between the mold assembly and the second worktable.

[0015] This invention also proposes a method for preparing U-shaped specimens for intergranular corrosion, comprising: Place the sample on the mold assembly; The power system is started, controlling the pressure head to move downwards, and using the arc-shaped end of the pressure head to press the sample into the U-shaped groove of the mold assembly; Under the pressure of the pressure head, the first mold body and the second mold body move towards each other on the side near the top of the U-shaped groove, causing the sample to bend and form an inner corner; During the pressing process, the pressure and stroke of the indenter are controlled in real time by the power system so that the inner angle of the sample reaches the preset value; Withdraw the indenter, allowing the specimen to spring back, ultimately forming a U-shaped specimen with parallel arms.

[0016] The intergranular corrosion U-shaped sample preparation device of this invention utilizes a mold body and a pressure head to form U-shaped samples. A hydraulic system controls the stable movement of the pressure head to apply pressure to the straight sample for bending, resulting in stable operation and higher efficiency. The sample pad and U-shaped groove position the sample during the forming process, ensuring the sample maintains the correct position and angle during extrusion forming, preventing displacement or damage, and guaranteeing processing accuracy. The mold assembly with dynamically adjustable opening angle, in conjunction with the precisely controlled pressure head, achieves accurate pre-deformation during the sample bending process, effectively compensating for material springback, achieving stable and efficient U-shaped sample preparation, and ensuring that the prepared sample structure meets testing standards. Furthermore, the mold assembly structure is simple and stable. The hydraulic system controls the pressure head movement, providing high efficiency. Stable pressure ensures a stable and efficient forming process, effectively guaranteeing processing accuracy. The control equipment uses sensors to acquire real-time data on the geometric and mechanical states of the sample during bending, achieving comprehensive and high-precision sensing of the forming process. This provides a reliable data foundation for intelligent decision-making, enabling dynamic adjustment of stroke and pressure to effectively prevent sample crushing or mold damage, thus improving equipment reliability and safety. By integrating a material parameter database and intelligent control algorithms, predictive control based on a data model is achieved, enabling adaptive compensation for the springback characteristics of different materials and batches of samples, significantly improving the success rate and batch consistency. Through the organic integration of various components and the system, a unified approach of high precision, high efficiency, high consistency, and high reliability is ultimately achieved in the preparation of intergranular corrosion U-shaped samples. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 An overall structural diagram of the intergranular corrosion U-shaped sample preparation device provided in one embodiment of the present invention; Figure 2 A structural diagram of the pressure head and mold assembly in one embodiment of the present invention; Figure 3 A structural diagram of the mold base in one embodiment of the present invention; Figure 4 A structural diagram of the mold body in one embodiment of the present invention; Figure 5 A schematic diagram of the structure of the initial state sample, the indenter, and the mold assembly provided in one embodiment of the present invention; Figure 6This is a schematic diagram of the structure of the sample, indenter, and mold assembly during processing in one embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the sample, indenter, and mold assembly after processing, provided in one embodiment of the present invention; Figure 8 This is a schematic diagram of the shape change during the sample processing in one embodiment of the present invention.

[0019] Label Explanation: 100. Tool cabinet; 200. Indenter head; 300. Power system; 400. Mold assembly; 500. Sample; 210. Arc-shaped end; 310. First workbench; 320. Second workbench; 330. Hydraulic transmission equipment; 340. Control equipment; 410. Mold base; 420. Mold body; 430. Spring; 411. First groove; 412. Superior arc groove; 421. First mold body; 422. Second mold body; 423. U-shaped groove; 424. Second groove; 425. Positioning groove; 426. Sample pad. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0021] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] Intergranular corrosion is a corrosion phenomenon that occurs at the grain boundaries of metallic materials. It severely damages the mechanical properties of materials. Intergranular corrosion tests are used to evaluate the corrosion resistance of materials in specific environments in order to optimize material selection and processing technology. The commonly used evaluation method is the bending method. However, in the bending method evaluation test, it is difficult to ensure that the size and shape of the intergranular corrosion specimen meet the standard or the specific requirements of the specimen evaluation. Not only is it difficult to ensure accuracy during the bending process, but the U-shaped specimen will also be unable to ensure the parallelism of its two arms due to springback after forming, thus failing to meet the specimen evaluation requirements and affecting the accuracy of the intergranular corrosion test evaluation.

[0023] Please see Figures 1 to 8 This invention proposes an intergranular corrosion U-shaped sample preparation device, including a tool cabinet 100, a pressure head 200, a power system 300, and a mold assembly 400. The tool cabinet 100 is used to place and fix the main structure of the sample preparation device. Its upper part is connected to the main structure of the sample preparation device, and the lower interior space is used to place spare fixtures and related tools. The power system 300 is located above the tool cabinet 100, and the pressure head 200 is connected to the power system 300. The pressure head 200 applies pressure to press parallel intergranular corrosion samples into U-shaped intergranular corrosion samples 500 of a specific shape or size. The power system 300 controls the stability of the pressure and stroke of the pressure head 200. The mold assembly 400 is located above the pressure head 200. Below, it works in conjunction with the pressure head 200 above to position and fix the U-shaped sample 500 during its forming process, ensuring its shape and size accuracy. During the pressing of the sample 500 by the pressure head 200, the mold assembly 400 bends the sample 500 into a U-shape. After the pressure head 200 presses down, the special structure of the mold assembly 400 ensures that the two arms of the sample 500 form a certain angle inward during forming, leaving a certain springback allowance. This allows the two arms to remain parallel after the sample 500 springs back, ensuring the accuracy of the U-shaped sample 500's shape. Using this sample preparation device, not only can the sample 500 maintain the correct position and angle during forming, preventing displacement or damage and improving processing accuracy and consistency, but it can also effectively avoid deviations in the sample 500's shape due to metal springback. Furthermore, the power system 300 provides pressure control for the movement of the pressure head 200, solving problems such as insufficient pressure and uncontrollable pressure. The entire forming process is more efficient and stable, effectively preventing damage to the sample 500 and ensuring its shape and size accuracy.

[0024] Please see Figures 1 to 7 According to an embodiment of the present invention, the indenter 200 is used to apply pressure to compress a parallel sample into a U-shaped sample of a specific shape or size that conforms to the test standard. The indenter 200 is arranged along a first direction, which is also the direction of movement of the indenter 200. One end of the indenter 200 is an arc-shaped end 210, which is used to bend and shape the sample 500. The size of the arc-shaped end 210 is determined according to the size of the sample 500 and the test standard. In the preparation process of the intergranular corrosion U-shaped sample 500, the indenter 200 is first positioned above the mold assembly 400 and at a certain distance from the mold assembly 400. The pressure of the indenter 200 pressing down bends the sample 500 within the mold assembly 400, and the arc-shaped end 210 cooperates with the mold assembly 400 to form the U-shaped sample 500.

[0025] Please see Figure 1According to one embodiment of the present invention, the pressure head 200 is connected to the power system 300, which controls the movement of the pressure head 200. The power system 300 is, for example, a hydraulic system, and the pressure head 200 can be a hydraulic pressure head 200 connected to the hydraulic system. The hydraulic system controls the movement of the pressure head 200, providing stable and controllable movement pressure. Intelligent control of the pressure head 200 through an external power system is not only more efficient and precise, but also effectively avoids situations where insufficient or unstable pressure during the molding process of the sample 500 prevents one-time molding, results in an imperfect molding structure, or even damage to the sample 500.

[0026] Please see Figure 1 According to a specific embodiment of the present invention, the power system 300 includes a first workbench 310, a second workbench 320, a hydraulic transmission device 330, and a control device 340. The first workbench 310 is disposed on the tool cabinet 100, and the second workbench 320 is disposed above the first workbench 310, with the two workbenches connected by columns to form a frame. The mold assembly 400 is disposed on the first workbench 310, and the hydraulic transmission device 330 and the control device 340 are disposed on the second workbench 320. The pressure head 200 is connected to the hydraulic transmission device 330 and moves between the mold assembly 400 and the second workbench 320. The pressure head 200 presses down on the sample 500 and cooperates with the structure of the mold assembly 400 to form a U-shaped sample 500. The control device 340 is connected to the hydraulic transmission device 330 to control the pressure and stroke of the pressure head 200. The hydraulic transmission device 330 amplifies the input force through the pressure transmission of the liquid, providing a stable and controllable motion pressure for the molding head 200 of the sample 500. The control device 340 enables intelligent control of the stroke and pressure of the hydraulic transmission device 330, which is easy to operate, highly efficient and stable in operation.

[0027] Please see Figure 1 According to an embodiment of the present invention, the control device 340 is the core of intelligent control, comprising a control unit, a sensor group, and a material parameter database. The sensor group is used to collect geometric and mechanical data of the sample 500 during the actual bending process in real time, and is connected to the control unit via signal lines. The material parameter database is stored in the memory of the control unit or a connected storage device, and stores optimized process parameters for different materials established through experimental calibration and machine learning. The control unit, as the processing core, instructs the hydraulic transmission device 330 to drive the pressure head 200 downwards, and, based on the real-time data fed back by the sensors and the target parameters in the database, makes real-time decisions through algorithms to control the hydraulic transmission device 330 to precisely and adaptively adjust the pressure and stroke of the pressure head 340 to compensate for material springback and ensure the accuracy of the final molded sample 500.

[0028] Please see Figure 1 According to one embodiment of the present invention, the sensor group includes a pressure sensor, a displacement sensor, and / or an angle sensor, which can monitor the pressure changes during the extrusion process in real time, as well as the bending angle of the sample 500 and / or the stroke of the indenter, to control the degree of bending of the sample 500 and thus ensure that a standard U-shaped sample is formed after springback. Specifically, the control unit is connected to the sensor group and is used to receive the real-time monitoring data from the sensors and, based on a preset material parameter database and control algorithm, send instructions to the hydraulic transmission device 330. The control unit works in conjunction with the hydraulic transmission device 330 to achieve closed-loop control of the pressure and stroke of the indenter 200. When the actual bending angle reaches a preset value, the pressurization is automatically stopped to ensure preparation accuracy. Specifically, a pressure sensor is mounted on the indenter 200 to monitor pressure changes during the extrusion process in real time. This helps to establish a more accurate model during data calibration and ensures more precise parameter control during the actual preparation of the sample 500, thereby improving the yield. A displacement sensor, such as a high-precision laser displacement sensor, can be installed on the side of the indenter 200 to accurately measure its stroke. An angle sensor, such as a non-contact optical angle sensor, is mounted on the side of the mold assembly 400 to monitor the bending angle of the sample 500 in real time. The sensors, control unit, and hydraulic transmission device 330 work together to precisely control the indenter stroke and the bending degree of the sample 500. This allows for accurate calibration of parameters such as the required bending angle of the sample 500, and precise control of its bending angle during sample preparation based on preset material parameters and control algorithms, ensuring that a standard sample is formed after springback.

[0029] Please see Figures 1 to 7 According to one embodiment of the present invention, a mold assembly 400 is disposed below the pressure head 200, and includes a mold base 410 and a mold body 420. The mold base 410 can be disposed on the first worktable 310, for example, and a first groove 411 is provided on the mold base 410; the mold body 420 includes a first mold body 421 and a second mold body 422, which are disposed in the first groove 411 and are respectively connected to the mold base 410 through elastic connectors. The first mold body 421 and the second mold body 422 cooperate to form a U-shaped groove 423 and a second groove 424. The U-shaped groove 423 is a through groove with its opening facing upward. The second groove 424 extends from the bottom of the U-shaped groove 423 to the bottom surface of the first groove 411. The arc-shaped end 210 is directly opposite the U-shaped groove 423 and the second groove 424; the second groove 424 can be, for example, a V-shaped groove to facilitate the relative movement of the first mold body 421 and the second mold body 422. Under the pressure of the pressure head 200, the sides of the first mold body 421 and the second mold body 422 near the top of the U-shaped groove 423 move towards each other, and the sides near the bottom of the second groove 424 move away from each other.

[0030] Please see Figures 1 to 7 According to an embodiment of the present invention, the arc of the arc-shaped end 210 and the center line of the U-shaped groove 423 are always in the same plane, ensuring the stability of the force on the sample 500 when the pressure head 200 is pressed down and the symmetry and precision of the structure of the U-shaped sample 500 after forming; in the free state, the two sides of the U-shaped groove 423 are parallel to each other, the sample 500 is placed above the U-shaped groove 423, the pressure head 200 moves along the first direction, and presses the sample 500 into the U-shaped groove 423 through the arc-shaped end 210 and bends it, under the pressure of the pressure head 200 The relative movement of the first mold body 421 and the second mold body 422 causes the two sides of the U-shaped groove 423 to contract inward to form an included angle. Correspondingly, when the sample 500 bends, a certain included angle is formed between the two arms, thus leaving a certain springback margin. After the pressure head 200 leaves, under the action of the elastic connector, the sides of the U-shaped groove 423 return to parallel. At the same time, under the springback action, the two arms of the sample 500 in the U-shaped groove 423 extend outward to a parallel state and are consistent with the shape of the U-shaped groove 423. Finally, the shape of the U-shaped sample 500 obtained meets the sample standard.

[0031] Please see Figures 1 to 7 According to an embodiment of the present invention, the shape of the first groove 411 on the mold base 410 matches the shape of the mold body 420. Specifically, for example, the bottom surface of the first groove 411 is arc-shaped. When the two sides of the first groove 411 are in contact with the mold body 420, there is a gap between the bottom of the first mold body 421 and the second mold body 422 and the first groove 411. The first mold body 421 and the second mold body 422 are stably connected to the mold base 410 through elastic connectors. Since a certain gap is formed below the first mold body 421 and the second mold body 422 through the second groove 424, when the pressure head 200 presses down, under the action of pressure, the upper parts of the first mold body 421 and the second mold body 422 near the U-shaped groove 423 move towards each other and the lower side near the second groove 424 moves away from each other. The bottom surface of the mold body 420 moves closer to the arc-shaped surface, and the two sides of the upper U-shaped groove 423 rotate inward to form an included angle.

[0032] It is understandable that the structural changes of the U-shaped groove 423 are consistent with the shape changes of the sample 500 during the forming process to ensure that the sample 500 can be formed smoothly. When the pressure head 200 presses down, the elastic connector will deform and elongate under tension, thus not hindering the structural changes of the mold body 420. In addition, since the springback angle of the sample 500 is small, only a small springback angle needs to be reserved during processing and forming. Therefore, the changes in the mold body 420 and the U-shaped groove 423 are small, which can maintain the overall stability of the device well. When the pressure head 200 leaves, the elastic connector recovers its deformation due to the disappearance of external force, thereby pulling the first mold body 421 and the second mold body 422 back to their original positions. The two sides of the U-shaped groove 423 return to parallel. The overall structure is simple.

[0033] Please see Figures 1 to 7 According to an embodiment of the present invention, an arc-shaped groove 412 is formed outward at the connection between the bottom surface of the first groove 411 and its two sides. The bottom of the first mold body 421 and the second mold body 422 respectively have corresponding protrusion structures. The protrusion structures are embedded in the arc-shaped groove 412 to connect the mold base 410 with the first mold body 421 and the second mold body 422. Under the pressure of the pressure head 200, the first mold body 421 and the second mold body 422 rotate with the protrusion structures on them as the center. As a result, the sides of the first mold body 421 and the second mold body 422 near the top of the U-shaped groove 423 move towards each other, and the sides near the bottom of the second groove 424 move away from each other, thereby realizing the structural change of the U-shaped groove 423. The mold base 410 and the mold body 420 are connected by the arc structure on both sides of the bottom, which enhances the stability of the connection and ensures the stability of the shape of the U-shaped groove 423 in the free state. At the same time, the first mold body 421 and the second mold body 422 can move during the molding process to adjust the shape of the U-shaped groove 423 at different molding stages, ensuring the stability of the U-shaped sample 500 molding process and the accuracy of the final sample 500 dimensions.

[0034] Please see Figures 1 to 7According to an embodiment of the present invention, a positioning part is further provided on the top surface of the mold body 420, which is arranged along the length direction of the mold assembly 400. The positioning part is symmetrically arranged on both sides of the U-shaped groove 423, and the sample 500 is disposed in the positioning part. It should be noted that the positioning part positions and fixes the sample 500. When the sample 500 is disposed in the positioning part, the axes of the pressure head 200, the U-shaped groove 423 and the sample 500 are located in the same plane, and the center of the sample 500 is perpendicular to the pressure head 200. This ensures that the sample 500 can maintain the correct position and angle when the pressure head 200 presses down, improves processing accuracy and consistency, prevents the sample 500 from being displaced or damaged during the extrusion process, and ensures that the final U-shaped sample 500 shape will not deviate and meets the test standards. The connection between the positioning part and the U-shaped groove 423 can be set as a rounded corner structure to avoid wear on the sample 500.

[0035] Please see Figures 1 to 7 According to an embodiment of the present invention, the positioning part includes a positioning groove 425 and a sample pad 426. The positioning groove 425 is formed on the top surface of the mold body 420, and the sample pad 426 is disposed in the positioning groove 425. The external dimensions of the sample pad 426 match the dimensions of the positioning groove 425, and the sample pad 426 has a groove inside, the internal dimensions of which match the dimensions of the sample 500, thereby enabling the sample 500 to be engaged in the sample pad 426 for positioning and fixation. The combination of the positioning groove 425 and the sample pad 426 for positioning the sample 500 ensures accurate and efficient positioning and facilitates the replacement of the sample pad 426. For samples 500 of different sizes, only the matching sample pad 426 needs to be replaced, simplifying processing.

[0036] Please see Figures 1 to 7According to an embodiment of the present invention, an elastic connector is connected to the mold base 410 and the mold body 420 to ensure the stability of the mold body 420 and to realize the structural change of the U-shaped groove 423 inside the mold body 420. It can be understood that since the U-shaped groove 423 and the second groove 424 on the mold body 420 divide the mold body 420 into two parts, the first mold body 421 and the second mold body 422, there is a gap between the first mold body 421 and the second mold body 422, and there is also a gap between the bottom surface of the mold body 420 and the mold base 410, the connection between the mold body 420 and the mold base 410 by the elastic connector can not only ensure the stability of the relative position of the mold body 420 in the free state, but also achieve buffering and adapt to the structural change of the mold body 420 by deformation during the pressing process of the pressure head 200. When the pressure is removed, the deformation of the elastic member can automatically restore the first mold body 421 and the second mold body 422 to their original position, realizing the final molding of the U-shaped sample 500. The use of elastic connectors can achieve structural changes in the U-shaped groove 423 of the mold body 420 while ensuring a stable connection, thereby adapting to the shape changes of the sample 500 during the molding process and ensuring the continuous stability of the entire molding process.

[0037] Please see Figures 1 to 7 According to an embodiment of the present invention, the elastic connector is, for example, a spring 430. The spring 430 is disposed at two end faces of the mold assembly 400 along the width direction. The spring 430 on each side is arranged along the length direction of the mold assembly 400 and symmetrically arranged about the U-shaped groove 423 to ensure the stability of the overall connection. Specifically, one end of the spring 430 is connected to the upper part of the first mold body 421 or the second mold body 422 and close to the U-shaped groove 423, and the other end is connected to the lower part of the mold base 410 and away from the U-shaped groove 423. When the pressure head 200 presses down, the first mold body 421 and the second mold body 422 rotate inward to realize the opposite movement of the upper U-shaped groove portion, thereby pulling the spring 430 along the length direction of the spring 430. When the pressure head 200 leaves, the spring 430 returns to its original length, driving the mold body 420 back to its original position and stably connecting with the mold base 410.

[0038] Please see Figures 1 to 8According to an embodiment of the present invention, before preparing the intergranular corrosion U-shaped sample 500, a corresponding material parameter database needs to be established through experimental calibration. It is understood that in the mold body 420, the inclination angle of the second groove 424 at the bottom of the U-shaped groove 423 is a fixed value. During extrusion molding, the inward angle range of the sample 500 is generally 0°~10°. This design can meet the requirements of most conventional metal materials in the industry. During parameter calibration, when the mold extrudes to the bottom of the second groove 424 at the bottom of the U-shaped groove 423, the inward angle of the sample 500 is at its maximum. If, after the sample 500 rebounds, the two arms still open outwards, it is necessary to replace the mold body 420 with one having a larger inclination angle for the second groove 424 to accommodate samples with a larger elastic modulus.

[0039] Please see Figures 1 to 8 According to an embodiment of the present invention, for a suitable mold and a compatible sample material, the relationship between the pressure head stroke and the inner angle of different materials can be calibrated experimentally to establish a model relating the pressure head stroke and the springback amount of the inner angle. When the pressure head 200 presses downward, the sample 500 bends inward continuously. When the two arms of the sample 500 are parallel, the inner angle is zero. Using this as the origin, the final angle after springback is continuously tested under different pressure strokes during the continued downward pressing of the pressure head 200. The pressure head stroke and / or bending angle of the test sample can be recorded in real time using displacement sensors and / or angle sensors. After the pressure head 200 is withdrawn, the springback process of the sample is continuously monitored, and the final forming angle is recorded. If the two arms are not parallel after springback, the parameters are automatically adjusted and a retest is prompted. A model relating the pressure head stroke and other parameters of the material during sample preparation and the springback amount of the inner angle is established using machine learning algorithms, and preset parameters are determined. The data is stored in the built-in material parameter database of the intelligent control system. After the user selects the material through the interface, the system control unit automatically calls the preset pressure head stroke, pressure parameters, etc. The material parameter database allows for rapid adaptation to various metal materials, greatly expanding the application range. It also eliminates the need for repeated adjustments, significantly improving preparation efficiency. The use of multi-sensor automated control ensures good consistency.

[0040] Please see Figures 1 to 8It should be noted that even if different materials are eventually bent to the same angle, their internal stress state and work hardening degree will be different. Therefore, during the material parameter database calibration stage, pressure sensors work synchronously with displacement and angle sensors. The pressure sensor monitors pressure changes during the extrusion process. The pressure curve is correlated with the material deformation characteristics, containing key mechanical property information such as the material's yield strength and strain hardening index. The control unit not only records different indenter strokes and their corresponding inner angles and final angles after springback, but also records the pressure-displacement curve of the entire pressing process, including characteristic points on the pressure-displacement curve, such as proportional limit points and yield points. After automatically extracting the required parameters, the control unit can establish a higher-level model containing mechanical features through machine learning algorithms. It can establish a model by correlating mechanical property information with springback amount. For example, it can establish a model by using pressure curve features and indenter stroke with springback amount, and identify yield points through algorithms. The stroke can be dynamically adjusted to avoid over- or under-pressure. By recording the special cases of parameters and results during each extrusion process, the material parameter database can be optimized. Thus, the device can adapt to the springback characteristics of different materials, control the degree of bending, and ensure that the springbacked sample meets the U-shaped dimensions required by standards such as GB / T4334-2020. For example, the model reveals that when the pressure curve reaches a clear yield plateau, a further 2mm of pressure results in the most stable springback for a certain sample (sample 500). This makes the final forming control no longer a simple stroke control, but a process control based on the actual mechanical state of the material, significantly improving the accuracy and generalization ability of the database. During the sample 500 preparation stage, not only are preset indenter stroke and inner angle target values ​​called, but a standard reference pressure-displacement curve is also loaded into memory. During the actual bending process, the control unit can perform real-time triple comparisons. If inconsistencies are found between the real-time pressure curve and the reference curve in the elastic phase, an adaptive strategy can be triggered, such as fine-tuning the indenter stroke to compensate for expected springback variations, ensuring a high yield.

[0041] Please see Figures 1 to 8According to an embodiment of the present invention, when preparing the intergranular corrosion U-shaped sample 500, the sample 500, after being soaked and treated in the test solution, is first placed in the groove of the sample pad 426 above the mold body 420. The corresponding sample pad 426 is selected according to the size of the sample 500 to ensure the accuracy of the position and angle of the sample 500. The pressure head 200 is connected to the hydraulic transmission device 330 and is located at a certain height above the sample 500. After the pressure and stroke of the pressure head 200 are preset and adjusted by the control device 340, the power system 300 is started to control the pressure head 200 to move downward. The movement direction of the pressure head 200 is perpendicular to the plane of the sample 500, and the arc-shaped end 210 is located at the center of the sample 500 after pressing down. The pressure head 200 presses down the sample 500 and extrudes it into shape in the U-shaped groove 423 of the mold body 420. When the pressure head 200 presses down... After the sample 500 reaches the bottom of the U-shaped groove 423, it continues to be pressed down. Due to the gaps in the middle and bottom of the mold body 420, the first mold body 421 and the second mold body 422 rotate inward under pressure, causing the two sides of the upper U-shaped groove 423 to contract inward and form a certain angle. The sample 500 is squeezed in the U-shaped groove 423 to form an approximate U-shaped structure with two arms at a certain angle. Then, the pressure head 200 moves upward and leaves the sample 500 and the mold body 420. The first mold body 421 and the second mold body 422 return to their original positions under the action of the springs 430 on both sides. The two sides of the U-shaped groove 423 return to parallel. At the same time, the sample 500 springs back to the point where the two arms are parallel and consistent with the structure of the U-shaped groove 423. This completes the preparation of the intergranular corrosion U-shaped sample 500 and ensures that the shape of the final sample 500 meets the test standards, providing an accurate evaluation.

[0042] Please see Figures 1 to 8 This invention also proposes a method for preparing U-shaped intergranular corrosion specimens. Using the aforementioned intergranular corrosion U-shaped specimen preparation apparatus, the method precisely controls the bending process of the specimen 500, utilizing a material parameter database and real-time sensor monitoring to ensure that the specimen 500 forms a standard U-shaped structure after springback. Specifically, it includes the following steps: Place sample 500 on the mold assembly; The power system 300 is started, controlling the pressure head 200 to move downwards, and using the arc-shaped end 210 of the pressure head 200 to press the sample 500 into the U-shaped groove 423 of the mold assembly 400; Under the pressure of the pressure head 200, the first mold body 421 and the second mold body 422 move towards each other on the side near the top of the U-shaped groove 423, causing the sample 500 to bend and form an inner corner. During the pressing process, the pressure and stroke of the pressure head 200 are controlled in real time by the power system 300 so that the inner angle of the sample 500 reaches the preset value. Withdraw the indenter by 200°, allowing the specimen to spring back 500°, ultimately forming a U-shaped specimen with parallel arms.

[0043] Please see Figures 1 to 8 According to an embodiment of the present invention, a material parameter database is established through the following steps: For various materials, the inner angle of the sample 500 and the final angle after springback were tested under different indenter strokes. A model relating the pressure head stroke to the inner corner springback amount was established using machine learning algorithms. The model data is stored in a material parameter database.

[0044] Please see Figures 1 to 8 Understandably, before batch preparation of samples, parameters are first calibrated experimentally and stored in a database system. Specifically, the material or batch of sample 500 is first determined. The sample 500 used for calibration is placed in the corresponding mold. The control unit controls the indenter 200 to press down at a constant speed. Displacement sensors, angle sensors, and pressure sensors simultaneously collect data and record a series of key data points. For example, when the indenter stroke is S1, the inward buckling angle of the sample is α1, and the final angle after rebound is β1. When the stroke is S2, the corresponding values ​​are α2 and β2, and so on, until the sample 500 is bent to the maximum inward buckling angle. The pressure sensor simultaneously records the stroke and pressure curves. Subsequently, machine learning algorithms are used for model training. For example, the feature values ​​of the indenter stroke and pressure curve (such as the stroke corresponding to the yield point, the maximum pressure value, etc.) are used as input features, and the final angle after rebound is used as the output target. After training, a high-precision prediction model is obtained. Finally, the model parameters (such as the optimal indenter stroke and the expected inward buckling angle corresponding to the material sample) are stored in the material parameter database. This process yields a quantifiable and reusable digital model. By introducing mechanical signals (pressure curves) and machine learning algorithms, the established model can more profoundly reflect the essential characteristics of the material, significantly improving the accuracy of springback prediction. For materials of the same grade but different batches, more precise control can be achieved through pre-calibration, fundamentally solving the problem of inconsistent sample molding caused by material performance fluctuations.

[0045] Please see Figures 1 to 8It should be noted that during the preparation of sample 500, controlling the pressure and stroke of the indenter 200 is a multivariable, closed-loop real-time control process. After the user selects the material, the control unit retrieves preset targets such as indenter stroke, inner angle, and other parameters from the database, as well as the benchmark pressure-displacement curve for comparison. After the power system is started, the indenter begins to press down. During the pressing process, the displacement sensor provides feedback on the real-time stroke, and the control unit adjusts the hydraulic output through a PID algorithm to ensure that the indenter stroke accurately approaches the target value. The angle sensor provides feedback on the real-time inner angle, and the control unit continuously compares the real-time inner angle with the preset inner angle. If a slight difference in material properties causes the inner angle to be too large, the pressure stroke will be dynamically adjusted to terminate the downward pressure, stopping before the pressure head reaches the target value to prevent over-bending, and vice versa. Throughout the process, the pressure sensor monitors the pressure in real time and compares it with the reference curve. The control unit uses an algorithm to identify the mechanical yield point in real time and dynamically adjusts the stroke to avoid over-pressure or under-pressure. When yield is detected, the material has entered the stable plastic deformation stage. If the actual pressure continues to be higher than the safety threshold of the reference curve, an overload risk is determined, such as an incorrect material grade or defects. At this time, the pressure will be stopped immediately and an alarm will be triggered to avoid damage to the sample or mold. This method can achieve intelligent control of the entire process. Through the fusion and cross-verification of information from displacement, angle, and pressure, it not only ensures processing accuracy but also has the ability to diagnose process anomalies and adaptive compensation, greatly improving the controllability, stability, and yield of the preparation process.

[0046] Please see Figures 1 to 8According to an embodiment of the present invention, this method is a coherent and intelligent process. First, the sample 500 is placed in the matching sample pad 426 for precise positioning. The operator selects the material grade on the control interface. After receiving the instruction, the control unit retrieves the complete set of preset parameters corresponding to the material from the material parameter database. After the power system 300 is started, the control unit drives the hydraulic transmission device 330, causing the pressure head 200 to begin pressing down according to the preset parameters. During the pressing process of the pressure head 200, the sensor group coordinates to monitor the parameters in real time and feeds them back to the control unit. The control unit synchronously processes the data from the three sensors. According to the data, a closed-loop decision-making process is performed, with the displacement, angle, and pressure three-loop closed-loop control system working simultaneously to ensure that the sample bending process follows both the preset geometric path and the expected mechanical laws. When the control conditions are met, the control unit instructs the hydraulic transmission device 330 to retract the pressure head 200. The first mold body 421 and the second mold body 422 in the mold assembly 400 automatically reset under the restoring force of the spring 430, the U-shaped groove 423 returns to a parallel state, and the sample 500 rebounds under its own elasticity. Since its inner angle has been precisely controlled, it forms a standard U-shaped sample with parallel arms after rebounding. Through the above collaborative working process, the specially designed mold structure is combined with multi-sensor information fusion control to achieve intelligent prediction and adaptive control, ensuring high precision, high consistency, and high reliability in the preparation of intergranular corrosion U-shaped samples. At the same time, it can achieve one-click preparation and can quickly adapt to different materials by switching database parameters, greatly improving preparation efficiency. The system has adaptive capabilities, which can effectively compensate for material performance fluctuations and prevent processing abnormalities, greatly reducing scrap rate and equipment risk. Furthermore, the system can also record the actual parameters and results of each preparation. If a systematic deviation is found from the database prediction, it can prompt the administrator to iteratively optimize the database model, thereby enabling the system to self-evolve.

[0047] In summary, the intergranular corrosion U-shaped sample preparation device of the present invention utilizes the mold assembly 400 and the pressure head 200 to form the U-shaped sample 500. The mold body 420 and the sample pad 426 limit and fix the sample 500, ensuring the accuracy of the position and angle of the sample 500 during the forming process, preventing damage to the sample 500, and improving processing accuracy and consistency. Unlike traditional fixed groove molds, the structure of the mold body 420 of the present invention can be flexibly changed. The second groove 424 below the U-shaped groove 423 and the gap between the bottom of the mold body 420 and the mold base 410 allow the first mold body 421 and the second mold body 422 to be subjected to pressure. The system enables relative motion, allowing the sides of the U-shaped groove 423 to bend inward at a certain angle to properly bend the sample 500. After the pressure head 200 leaves, the U-shaped groove 423 returns to parallel under the action of the spring 430. The sample 500 inside the U-shaped groove 423 can maintain the parallelism of its two arms after rebounding, ensuring that the final sample 500 prepared meets the test requirements and enables more accurate evaluation. The mold assembly 400 has a simple and stable structure. The power system 300 controls the movement of the pressure head 200, providing uniform and stable pressure. The entire molding process is smooth and efficient, effectively ensuring processing accuracy and avoiding errors from human operation, as well as situations such as insufficient pressure, incomplete molding in one step, or damage to the sample.

[0048] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

[0049] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. An apparatus for preparing U-shaped samples of intergranular corrosion, characterized in that, include: The pressure head has an arc-shaped end. A power system is connected to the pressure head and controls its movement. A mold assembly is disposed below the pressure head, the mold assembly comprising: A mold base, on which a first groove is provided; The first mold body and the second mold body are disposed in the first groove and are respectively connected to the mold base through elastic connectors; The first mold body and the second mold body cooperate to form a U-shaped groove and a second groove, and the second groove extends from the bottom surface of the U-shaped groove to the bottom surface of the first groove; Under the pressure of the pressure head, the first mold body and the second mold body move towards each other on the side near the top of the U-shaped groove, and move away from each other on the side near the bottom of the second groove.

2. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 1, characterized in that, The bottom surface of the first groove is arc-shaped, and there is a gap between the bottom of the first mold body and the second mold body and the first groove.

3. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 2, characterized in that, An outwardly curved groove is formed at the connection between the bottom surface of the first groove and the two sides of the first groove. The bottom of the first mold body and the second mold body respectively have a corresponding protrusion structure. The protrusion structure is embedded in the curved groove to connect the mold base with the first mold body and the second mold body. Under the pressure of the pressure head, the first mold body and the second mold body rotate around the protrusion structure on them, so that the sides of the first mold body and the second mold body near the top of the U-shaped groove move towards each other, and the sides near the bottom of the second groove move away from each other.

4. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 1, characterized in that, The top surface of the mold body is also provided with a positioning part, which is arranged along the length direction of the mold assembly, and the positioning part is symmetrically arranged on both sides of the U-shaped groove, and the sample is placed in the positioning part.

5. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 4, characterized in that, The positioning unit includes: A positioning groove is formed on the top surface of the mold body; A sample pad is disposed in the positioning groove. The external dimensions of the sample pad match the dimensions of the positioning groove, and the internal dimensions of the sample pad match the dimensions of the sample. The sample is engaged within the sample pad.

6. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 1, characterized in that, The elastic connector is a spring, which is disposed at both ends of the mold assembly along the width direction, and the spring on each side is arranged along the length direction of the mold assembly and symmetrically arranged about the U-shaped groove.

7. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 6, characterized in that, One end of the spring is connected to the top of the first mold body or the second mold body and close to the U-shaped groove, and the other end is connected to the bottom of the mold base and away from the U-shaped groove.

8. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 1, characterized in that, The power system is a hydraulic system, which includes: A hydraulic transmission device is connected to the pressure head; A control device is connected to the hydraulic transmission device to control the pressure and stroke of the pressure head.

9. The apparatus for preparing intergranular corrosion U-shaped samples according to claim 8, characterized in that, The hydraulic system also includes: A first workbench, wherein the mold assembly is disposed on the first workbench; A second workbench is disposed above the first workbench, and the hydraulic transmission device and the control device are disposed on the second workbench; The first worktable and the second worktable are connected by a column, and the pressure head is connected to the hydraulic transmission device and moves between the mold assembly and the second worktable.

10. A method for preparing a U-shaped sample for intergranular corrosion, characterized in that, include: Place the sample on the mold assembly; The power system is started, controlling the pressure head to move downwards, and using the arc-shaped end of the pressure head to press the sample into the U-shaped groove of the mold assembly; Under the pressure of the pressure head, the first mold body and the second mold body move towards each other on the side near the top of the U-shaped groove, causing the sample to bend and form an inner corner; During the pressing process, the pressure and stroke of the indenter are controlled in real time by the power system so that the inner angle of the sample reaches the preset value; Withdraw the indenter, allowing the specimen to spring back, ultimately forming a U-shaped specimen with parallel arms.

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