Fatigue test testing device and testing process for aluminum alloy stamping die

Abstract

The application relates to the technical field of aluminum alloy stamping die detection, and specifically discloses a fatigue test device and a test process for an aluminum alloy stamping die. The device comprises multiple sets of elastic supporting assemblies and multiple sets of elastic pressing assemblies which are distributed below the die and above the die. The elastic supporting assemblies and the elastic pressing assemblies realize stress-free, self-adaptive and stable clamping of the complex stamping die. Meanwhile, the orthogonal three-axis guide rail drives the detection probe to realize programmed precise movement in the three-dimensional space, so that the detection probe can reach every concave-convex area of the die surface without dead angle to perform scanning, thereby providing a stable workpiece posture and an accurate probe path for high-precision detection from the physical level, and overcoming the bottleneck that large special-shaped workpieces are difficult to be stably clamped and comprehensively detected. The device also integrates a double-physical-field sensing mechanism of eddy current and differential capacitance, and synchronously analyzes the eddy current impedance signal and the differential capacitance signal, so that the detection equipment has the ability to distinguish the base crack and the surface aluminum adhesion.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy stamping die testing technology, and in particular to a fatigue testing device and testing process for aluminum alloy stamping dies. Background Technology

[0002] Aluminum alloy stamping is a key process in modern manufacturing, particularly in the automotive and aerospace industries, for producing lightweight, high-strength structural and body panels. The core equipment of this process is the aluminum alloy stamping die, typically made of high-strength die steel. It achieves specific workpiece shapes by plastically deforming aluminum alloy sheets under immense impact loads. In long-term, high-frequency continuous stamping operations, the die's working parts not only endure cyclic impact stresses but also experience intense friction with the highly fluid aluminum alloy material. This combined effect easily induces material fatigue in the die steel matrix, leading to the initiation and propagation of microcracks. Simultaneously, the high temperature and pressure conditions cause aluminum alloy material to easily adhere to the die cavity surface, forming an aluminum-adhesive layer. Both fatigue cracks and aluminum adhesion directly result in quality defects such as scratches and deformation in the stamped parts and accelerate die failure. Therefore, effective detection of both is crucial for ensuring production quality and die lifespan.

[0003] Currently, fatigue testing of mold steel mainly relies on a series of mature non-destructive testing technologies. Magnetic particle testing is one of the most widely used methods. Its principle is to magnetize the ferromagnetic mold steel; fatigue cracks on the surface or near the surface disrupt the continuity of the magnetic field, attracting magnetic particles to accumulate and form visible indicators. Another commonly used method is penetrant testing, which involves applying colored or fluorescent penetrant to the mold surface, allowing it to penetrate into the crack opening. After cleaning, a developer is used to extract the penetrant from the defect, achieving visualization. For deeper defects, ultrasonic testing is often used, employing piezoelectric crystals to emit high-frequency sound waves and receiving the reflected echoes from cracks and other defects to determine their location and size. All these technologies aim to identify the physical discontinuities in the mold steel matrix caused by fatigue.

[0004] However, when applied to the specific scenario of aluminum alloy stamping dies, the aforementioned conventional testing techniques cannot effectively distinguish between fatigue cracks in the die steel substrate and aluminum alloy layers adhering to the die surface. Magnetic particle and penetrant testing respond to any surface opening or near-surface discontinuity; the edges and gaps of adhered aluminum produce false indications highly similar to cracks, leading to misjudgments. Ultrasonic testing shows a weak response to thin layers of adhered aluminum, and its signal is easily interfered with by complex surface features.

[0005] Therefore, conventional technologies lack an integrated detection device that can reliably distinguish and differentiate between aluminum adhesion and cracks, two defects with different properties but equally serious consequences, under complex curved surface conditions. Summary of the Invention

[0006] To overcome the problem that conventional testing methods are difficult to distinguish between aluminum adhesion and substrate fatigue cracks on complex curved aluminum alloy stamping dies, and that the testing reliability is insufficient, this application provides a fatigue testing device and testing process for aluminum alloy stamping dies.

[0007] This application provides a fatigue testing device for aluminum alloy stamping dies, which adopts the following technical solution: A fatigue testing device for aluminum alloy stamping dies includes a test platform, a positioning mechanism for positioning the stamping die body, a fatigue detection mechanism for performing fatigue detection on the upper surface of the stamping die body, and a horizontal moving mechanism for moving the fatigue detection mechanism along the surface of the stamping die body.

[0008] Optionally, the positioning mechanism includes multiple sets of support components for elastically supporting the lower surface of the stamping die and multiple sets of pressing components for pressing the upper surface of the stamping die body. Each of the support components is spaced apart on the test table and located below the stamping die body, and each of the pressing components is spaced apart on the test table and located above the stamping die body near the edge.

[0009] Optionally, the support assembly includes a support base, a rod slidably inserted into the top of the support base, and a support spring sleeved outside the insertion. The top of the rod is provided with a support pad, and one end of the support spring is fixedly abutted against the top of the support base, while the other end is fixedly abutted against the support pad.

[0010] Optionally, the pressing assembly includes a fixed base disposed on the test bench, a pressing rod rotatably mounted on the fixed base, and a torsion spring disposed on the rotation axis of the pressing rod, the torsion spring being used to provide a torque for the pressing rod to rotate toward the upper surface of the test bench.

[0011] Optionally, the horizontal movement mechanism includes an X-axis sliding guide rail, a Y-axis sliding guide rail, and a Z-axis lifting guide rail. Two X-axis sliding guide rails are provided and installed at intervals on the test platform. The Y-axis sliding guide rail is installed on the sliding portion of the two X-axis sliding guide rails. The Z-axis lifting guide rail is installed on the sliding portion of the Y-axis sliding guide rail, and the lifting portion can move perpendicular to the test platform. The fatigue detection mechanism is provided on the lifting protection of the Z-axis lifting guide rail.

[0012] Optionally, the fatigue detection mechanism includes a mounting base fixed to the lifting part of the Z-axis lifting guide rail, an eddy current coil fixed below the mounting base, and two semi-cylindrical capacitor plates disposed outside the eddy current coil. The two ends of the eddy current coil are respectively connected to an external eddy current detector host. Each of the two capacitor plates has a terminal block fixed on one side facing away from each other. Two wires are fixedly connected to each terminal block. One end of each wire is connected to the terminal block, and the other end of each wire is connected to the output terminal of the high-frequency signal generator and the input terminal of the differential amplifier of the external measurement circuit, respectively.

[0013] Optionally, a shielding cover for shielding the electric field generated by the eddy current coil is provided between the eddy current coil and the two capacitor plates, and a plurality of slot arrays are provided at radial intervals along the axis at the bottom of the shielding cover.

[0014] Optionally, each of the two capacitor plates has a detection probe at its bottom that contacts the surface of the stamping die body, and each of the two capacitor plates has an elastic telescopic component at its top that allows the corresponding detection probe to elastically abut against the surface of the stamping die body.

[0015] Optionally, the elastic telescopic component includes a support rod, a sliding limiting plate, and a retaining spring. One end of the support rod is fixedly connected to the top of the capacitor plate, and the other end is slidably installed in the mounting base. The mounting base has a corresponding receiving groove. The sliding limiting plate is slidably limited and installed in the receiving groove. One end of the retaining spring is connected to the end of the sliding limiting plate away from the support rod, and the other end is fixedly connected to the bottom wall of the receiving groove.

[0016] This application also provides a fatigue testing process for aluminum alloy stamping dies, which uses the fatigue testing device for aluminum alloy stamping dies described above and includes the following steps: S1: Place the stamping die body on multiple support pads, and then rotate each pressing rod to make the pressing rod abut against the upper surface of the stamping die body; S2: Drive the X-axis sliding guide, Y-axis sliding guide and Z-axis lifting guide to work, move the two detection probes to the upper surface of the stamping die body and elastically abut against the upper surface of the stamping die body; S3: The two detection probes slide along the upper surface of the stamping die body through the X-axis sliding guide, Y-axis sliding guide and Z-axis lifting guide; S4: Inspect various locations along the surface of the stamping die body to detect and determine whether the surface of the stamping die body has cracks or aluminum adhesion.

[0017] In summary, this application includes at least one of the following beneficial technical effects: 1. This application achieves stress-free, adaptive, and stable clamping of complex stamping dies by using multiple sets of elastic support components distributed below the die and multiple sets of elastic pressing components above the die. At the same time, the orthogonal triaxial guide rail drives the detection probe to achieve programmed precision movement in three-dimensional space, ensuring that the detection probe can reach every concave and convex area of ​​the die surface for scanning without blind spots. From a physical perspective, it provides a stable workpiece posture and a precise probe path for high-precision detection, overcoming the bottleneck of large irregular parts being difficult to stably clamp and comprehensively inspect.

[0018] 2. This application integrates a dual-physical-field sensing mechanism of eddy current and differential capacitance. By simultaneously analyzing the eddy current impedance signal and the differential capacitance signal, the detection device is able to distinguish between matrix cracks and surface aluminum adhesion.

[0019] 3. To ensure the purity and reliability of the dual-mode signal, this application sets a grounding shield with a radial slot array outside the eddy current coil, which effectively isolates harmful electric field interference. In addition, each capacitor plate is equipped with an independent contact detection probe with an elastic telescopic component, so that the capacitance measurement can adapt to the surface undulation and maintain stable electrical contact. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the test device from a first-view perspective in an embodiment of this application.

[0022] Figure 2 This is a schematic diagram of the overall structure of the test device from a second perspective in an embodiment of this application.

[0023] Figure 3 yes Figure 1 A schematic diagram of the horizontal moving mechanism.

[0024] Figure 4 yes Figure 3 A schematic diagram of the Z-axis lifting guide rail and fatigue detection mechanism.

[0025] Figure 5 yes Figure 4 A schematic diagram of the structure of the fatigue testing facility.

[0026] Figure 6 yes Figure 5 A schematic diagram of the internal structure of a fatigue testing mechanism.

[0027] Figure label: 1. Test bench; 2. Positioning mechanism; 21. Support assembly; 211. Support base; 212. Insert rod; 213. Support spring; 214. Support pad; 22. Pressing assembly; 221. Fixing base; 222. Pressing rod; 3. Horizontal moving mechanism; 31. X-axis sliding guide rail; 32. Y-axis sliding guide rail; 33. Z-axis lifting guide rail; 4. Fatigue detection mechanism; 41. Mounting base; 42. Eddy current coil; 43. Capacitor plates; 5. Shielding cover; 6. Slit array; 7. Detection probe; 8. Elastic telescopic component; 81. Support rod; 82. Sliding limit plate; 83. Abutment spring. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail below.

[0029] This application discloses a fatigue testing device for aluminum alloy stamping dies.

[0030] Reference Figure 1 and Figure 2 A fatigue testing device for aluminum alloy stamping dies includes a test bench 1, a positioning mechanism 2 for positioning the stamping die body, a fatigue detection mechanism 4 for fatigue detection of the upper surface of the stamping die body, and a horizontal moving mechanism 3 for moving the fatigue detection mechanism 4 along the surface of the stamping die body.

[0031] Reference Figure 1 and Figure 2 The positioning mechanism 2 includes multiple sets of support components 21 for elastically supporting the lower surface of the stamping die and multiple sets of pressing components 22 for pressing the upper surface of the stamping die body. Each support component 21 is arranged at intervals on the test table 1 and located below the stamping die body, and each pressing component 22 is arranged at intervals on the test table 1 and located above the stamping die body near the edge.

[0032] Reference Figure 1 and Figure 2 The support assembly 21 includes a support base 211, a rod 212 slidably inserted into the top of the support base 211, and a support spring 213 sleeved outside the insertion. The top of the rod 212 is provided with a support pad 214. One end of the support spring 213 is fixed to the top of the support base 211, and the other end is fixed to the support pad 214.

[0033] Reference Figure 2 The pressing assembly 22 includes a fixed base 221 disposed on the test platform 1, a pressing rod 222 rotatably mounted on the fixed base 221, and a torsion spring disposed on the rotation axis of the pressing rod 222. The torsion spring is used to provide a torque for the pressing rod 222 to rotate toward the upper surface of the test platform 1.

[0034] Reference Figure 2 and Figure 3 The horizontal moving mechanism 3 includes an X-axis sliding guide rail 31, a Y-axis sliding guide rail 32, and a Z-axis lifting guide rail 33. Two X-axis sliding guide rails 31 are provided and installed at intervals on the test bench 1. The Y-axis sliding guide rail 32 is installed on the sliding part of the two X-axis sliding guide rails 31. The Z-axis lifting guide rail 33 is installed on the sliding part of the Y-axis sliding guide rail 32, and the lifting part can move perpendicular to the test bench 1. The fatigue detection mechanism 4 is set on the lifting protection of the Z-axis lifting guide rail 33.

[0035] Reference Figure 4 , Figure 5 and Figure 6 The fatigue testing mechanism 4 includes a mounting base 41 fixed on the lifting part of the Z-axis lifting guide rail 33, an eddy current coil 42 fixed below the mounting base 41, and two semi-cylindrical capacitor plates 43 disposed outside the eddy current coil 42. The two ends of the eddy current coil 42 are respectively connected to the external eddy current testing instrument host.

[0036] Each of the two capacitor plates 43 has a terminal block fixed on one side facing away from each other. Two wires are fixedly connected to each terminal block. One end of each wire is connected to the terminal block, and the other end of each wire is connected to the output terminal of the high-frequency signal generator and the input terminal of the differential amplifier of the external measurement circuit, respectively.

[0037] When a high-frequency current is applied to the eddy current coil 42, the eddy current coil 42 generates an alternating magnetic field that acts on the stamping die body. By detecting the change in the impedance of the eddy current coil 42, abnormalities in the conductivity and magnetic permeability of the near surface and inside of the stamping die body can be sensed, making it extremely sensitive to matrix discontinuities such as fatigue cracks.

[0038] Terminals are fixed on opposite sides of the two semi-cylindrical capacitor plates 43. Each terminal is connected to two wires, which are respectively connected to the output terminal of the high-frequency signal generator of the external measurement circuit and the input terminal of the differential amplifier, thus forming a measurement circuit with separate drive and detection.

[0039] The eddy current detector is an existing testing device. Its testing principle is existing technology and will not be elaborated here. The external measurement circuit is a dual-channel differential capacitance measurement circuit, which is used to excite and read the signals of the two capacitor plates 43 and calculate their difference. Its core is to eliminate common-mode interference and amplify the difference signal.

[0040] The dual-channel differential capacitance measurement circuit includes a precision high-frequency signal source capable of generating a pure sine wave, a power divider for accurately replicating the signal into two fully synchronous, same-frequency, same-phase, and same-amplitude signals to excite the two capacitor plates 43, a dual-channel lock-in amplifier, and a high-speed differential amplifier.

[0041] During operation, two in-phase excitation signals are applied to two capacitor plates 43A and B, respectively, forming an electric field on the surface of the stamping die body. When the detection probe scans an intact area or an area with only cracks, the electrical environment under the two capacitor plates 43 changes synchronously and to the same degree. Therefore, the changes in C_A and C_B are almost the same. After being subtracted by the differential amplifier, the output ΔC is almost zero or remains stable.

[0042] When the aluminum-adhesive area is swept over, the uneven adhesion of the aluminum layer will asymmetrically and to varying degrees change the dielectric constant and effective distance under capacitor plates 43 A and B, resulting in asynchronous and unequal changes in C_A and C_B.

[0043] At this point, the output ΔC of the differential amplifier will exhibit significant and characteristic fluctuations. This circuit, through differential design, suppresses common-mode interference such as probe lift-off and temperature drift, while greatly highlighting the unique local non-uniformity signal characteristic of aluminum adhesion.

[0044] The two capacitor plates 43 act as differential capacitance sensors, measuring the difference in capacitance between themselves and the surface of the stamping die body, exhibiting extremely high sensitivity to localized and non-uniform changes in the surface dielectric properties. By simultaneously analyzing the impedance signal from the eddy current coil 42 and the differential capacitance signal from the capacitor plates 43, and comparing their characteristic patterns, it is possible to effectively distinguish whether the signal originates from fatigue cracks in the substrate or from aluminum adhesion on the surface, thus solving the fundamental problem of high false positive rates in traditional single-detection techniques.

[0045] Reference Figure 5 and Figure 6 A shielding cover 5 is provided between the eddy current coil 42 and the two capacitor plates 43 to shield the electric field generated by the eddy current coil 42. The shielding cover 5 is made of brass. In other feasible embodiments, it can also be made of silver-plated copper with silver plating on the surface. Multiple slot arrays 6 are radially spaced along the axis at the bottom of the shielding cover 5.

[0046] By grounding, the shield 5 can almost completely confine the strong alternating electric field generated by the high-frequency voltage at both ends of the eddy current coil 42 inside its metal cavity, preventing the electric field from radiating outward and directly coupling to the adjacent, highly sensitive capacitor plate 43.

[0047] Without this shield 5, the electric field would become a huge, unstable background noise in the capacitance measurement channel, severely interfering with or even drowning out the weak capacitance signal reflecting aluminum adhesion.

[0048] Meanwhile, its specific radial slit array 6 structure at the bottom can greatly impede the alternating magnetic field generated by the eddy coil 42 for detection, and the magnetic field can effectively pass through these slits and act on the surface of the stamping die body.

[0049] Reference Figure 5 and Figure 6 Both capacitor plates 43 are provided with detection probes 7 at their bottoms that contact the surface of the stamping die body. In this embodiment, the detection probes 7 are made of tungsten copper alloy and their ends are provided as spherical surfaces that are easy to move and contact for detection. Both capacitor plates 43 are provided with elastic telescopic components 8 at their tops for making the corresponding detection probes 7 elastically contact the surface of the stamping die body.

[0050] The detection probe 7 makes direct mechanical contact with the surface of the stamping die body. This not only establishes a stable, low-impedance potential reference point for capacitance measurement, eliminating the interference of floating potentials on the die surface, but more importantly, it physically defines and stabilizes the measurement distance between the capacitor plate 43 and the die surface through the geometric length of the detection probe 7. The elastic telescopic component 8 at the top provides the corresponding detection probe 7 with a force that keeps it in elastic contact with the die surface.

[0051] When the horizontal moving mechanism 3 drives the detection probe 7 to move on the uneven surface of the stamping die body, in the face of local height changes, the two detection probes 7 can independently perform micro-elastic lifting and lowering under the action of the elastic telescopic component 8, thereby driving the two capacitor plates 43 connected to them to move synchronously.

[0052] This ensures that the spatial distance between the two capacitor plates 43 and the mold surface can adapt to changes in the local curvature in real time, while maintaining a slight, constant contact pressure. This greatly overcomes the problem of signal failure caused by drastic fluctuations in the lifting distance of traditional non-contact capacitive sensors on complex curved surfaces, providing a structural basis for the stable and reliable application of differential capacitance measurement in real industrial molds.

[0053] Reference Figure 5 and Figure 6The elastic telescopic component 8 includes a support rod 81, a sliding limiting plate 82, and an abutment spring 83. One end of the support rod 81 is fixedly connected to the top of the capacitor plate 43, and the other end is slidably installed in the mounting base 41. The mounting base 41 has a corresponding receiving groove. The sliding limiting plate 82 is slidably limited and installed in the receiving groove. One end of the abutment spring 83 is connected to the end of the sliding limiting plate 82 away from the support rod 81, and the other end is fixedly connected to the bottom wall of the receiving groove.

[0054] The surface of the aluminum alloy stamping die is subjected to moving inspection. When cracks and areas with aluminum adhesion are detected, these areas are marked differently, such as with fluorescent markings or other distinguishable markings. Then, the areas with aluminum adhesion are cleaned with cleaning tools. After cleaning, the areas with aluminum adhesion are inspected again to prevent cracks from appearing in the areas with aluminum adhesion. The same treatment is carried out on all areas with aluminum adhesion.

[0055] The implementation principle of the fatigue testing device for aluminum alloy stamping dies in this application embodiment is as follows: When the device is working, the body of the stamping die to be tested is first fixed to the test table 1 without stress by the positioning mechanism 2.

[0056] Subsequently, the horizontal moving mechanism 3 drives the detection probe to move precisely in three dimensions above the surface of the stamping die body according to the preset program. At each detection point, the detection probe performs two measurements simultaneously: in the eddy current detection channel, the high-frequency current drives the eddy current coil 42 to generate an alternating magnetic field. The magnetic field induces eddy currents on the surface of the stamping die body. When encountering cracks or adhered aluminum, the eddy current field is distorted and reacts on the eddy current coil 42, changing its impedance. This change is captured and analyzed by the eddy current detector. Meanwhile, in the capacitance detection channel, the high-frequency signal generator applies in-phase excitation to the two capacitor plates 43. The capacitor plates 43 form capacitive coupling with the mold surface through the contact detection probe 7 at the bottom. Due to the different effects of aluminum adhesion and cracks on the dielectric properties below the two capacitor plates 43, the capacitance values ​​of the two capacitor plates 43 are different. This difference signal is extracted by the differential amplifier.

[0057] The control system synchronously acquires and processes these two signals. By analyzing the intensity and phase characteristics of the eddy current signal and the fluctuation mode characteristics of the differential capacitance signal, and based on the specific correlation logic between them—for example, cracks cause drastic changes in the eddy current signal while the differential capacitance signal remains calm, and aluminum adhesion causes both to change significantly and synchronously—it can make a definitive judgment on whether the current detection point is a fatigue crack in the matrix or aluminum adhesion on the surface. Finally, it generates a defect distribution map covering the entire mold surface, thereby achieving efficient, accurate, and automated fatigue condition detection.

[0058] This application also discloses a fatigue testing process for aluminum alloy stamping dies, which uses the fatigue testing device for aluminum alloy stamping dies described above and includes the following steps: S1: Place the stamping die body on multiple support pads 214, and then rotate each pressing rod 222 so that the pressing rod 222 abuts against the upper surface of the stamping die body. S2: Drive the X-axis sliding guide rail 31, Y-axis sliding guide rail 32 and Z-axis lifting guide rail 33 to work, move the two detection probes 7 to the upper surface of the stamping die body and elastically abut against the upper surface of the stamping die body; S3: The two detection probes 7 are driven to slide along the upper surface of the stamping die body through the X-axis sliding guide rail 31, the Y-axis sliding guide rail 32 and the Z-axis lifting guide rail 33 for detection; S4: Inspect various locations along the surface of the stamping die body to detect and determine whether the surface of the stamping die body has cracks or aluminum adhesion.

[0059] The above are all optional embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fatigue testing device for aluminum alloy stamping dies, characterized in that: The test bench (1) is equipped with a positioning mechanism (2) for positioning the stamping die body, a fatigue detection mechanism (4) for fatigue detection of the upper surface of the stamping die body, and a horizontal moving mechanism (3) for moving the fatigue detection mechanism (4) along the surface of the stamping die body.

2. The fatigue testing device for aluminum alloy stamping dies according to claim 1, characterized in that: The positioning mechanism (2) includes multiple sets of support components (21) for elastically supporting the lower surface of the stamping die and multiple sets of pressing components (22) for pressing the upper surface of the stamping die body. Each of the support components (21) is spaced apart on the test table (1) and located below the stamping die body. Each of the pressing components (22) is spaced apart on the test table (1) and located above the stamping die body near the edge.

3. The fatigue testing device for aluminum alloy stamping dies according to claim 2, characterized in that: The support assembly (21) includes a support base (211), a plug rod (212) slidably inserted into the top of the support base (211), and a support spring (213) sleeved outside the plug rod. A support pad (214) is provided on the top of the plug rod (212). One end of the support spring (213) abuts and is fixed to the top of the support base (211), and the other end abuts and is fixed to the support pad (214).

4. The fatigue testing device for aluminum alloy stamping dies according to claim 2, characterized in that: The pressing assembly (22) includes a fixed base (221) disposed on the test platform (1), a pressing rod (222) rotatably mounted on the fixed base (221), and a torsion spring disposed on the rotation axis of the pressing rod (222). The torsion spring is used to provide a torque for the pressing rod (222) to rotate toward the upper surface of the test platform (1).

5. The fatigue testing device for aluminum alloy stamping dies according to claim 1, characterized in that: The horizontal moving mechanism (3) includes an X-axis sliding guide rail (31), a Y-axis sliding guide rail (32), and a Z-axis lifting guide rail (33). Two X-axis sliding guide rails (31) are provided and installed at intervals on the test bench (1). The Y-axis sliding guide rail (32) is installed on the sliding part of the two X-axis sliding guide rails (31). The Z-axis lifting guide rail (33) is installed on the sliding part of the Y-axis sliding guide rail (32), and the lifting part can move perpendicular to the test bench (1). The fatigue detection mechanism (4) is provided on the lifting protection of the Z-axis lifting guide rail (33).

6. The fatigue testing device for aluminum alloy stamping dies according to claim 5, characterized in that: The fatigue detection mechanism (4) includes a mounting base (41) fixed on the lifting part of the Z-axis lifting guide rail (33), an eddy current coil (42) fixed below the mounting base (41), and two semi-cylindrical capacitor plates (43) disposed outside the eddy current coil (42). The two ends of the eddy current coil (42) are respectively connected to the external eddy current detector host. Both capacitor plates (43) are fixed with terminals on opposite sides. Two wires are fixedly connected to each terminal. One end of each wire is connected to the terminal, and the other end of each wire is connected to the output terminal of the high-frequency signal generator and the input terminal of the differential amplifier of the external measurement circuit, respectively.

7. The fatigue testing device for aluminum alloy stamping dies according to claim 6, characterized in that: A shielding cover (5) is provided between the eddy current coil (42) and the two capacitor plates (43) to shield the electric field generated by the eddy current coil (42). The bottom of the shielding cover (5) is provided with a plurality of slot arrays (6) spaced radially along the axis.

8. The fatigue testing device for aluminum alloy stamping dies according to claim 6, characterized in that: Both capacitor plates (43) are provided with a detection probe (7) at the bottom to contact the surface of the stamping die body, and both capacitor plates (43) are provided with an elastic telescopic component (8) at the top to make the corresponding detection probe (7) elastically abut against the surface of the stamping die body.

9. The fatigue testing device for aluminum alloy stamping dies according to claim 8, characterized in that: The elastic telescopic component (8) includes a support rod (81), a sliding limiting plate (82), and a retaining spring (83). One end of the support rod (81) is fixedly connected to the top of the capacitor plate (43), and the other end is slidably installed in the mounting base (41). The mounting base (41) has a corresponding receiving groove. The sliding limiting plate (82) is slidably limited and installed in the receiving groove. One end of the retaining spring (83) is connected to the end of the sliding limiting plate (82) away from the support rod (81), and the other end is fixedly connected to the bottom wall of the receiving groove.

10. A fatigue testing process for aluminum alloy stamping dies, wherein the fatigue testing device for aluminum alloy stamping dies as described in any one of claims 1-9 is used for testing, characterized in that: The following steps are adopted: S1: Place the stamping die body on multiple support pads (214), and then rotate each pressing rod (222) so that the pressing rod (222) abuts against the upper surface of the stamping die body; S2: Drive the X-axis sliding guide rail (31), Y-axis sliding guide rail (32) and Z-axis lifting guide rail (33) to work, move the two detection probes (7) to the upper surface of the stamping die body and elastically abut against the upper surface of the stamping die body; S3: The two detection probes (7) are driven to slide along the upper surface of the stamping die body by the X-axis sliding guide rail (31), the Y-axis sliding guide rail (32) and the Z-axis lifting guide rail (33). At the same time, the eddy current coil (42) and the two capacitor plates (43) work. S4: Inspect various locations along the surface of the stamping die body to detect and determine whether the surface of the stamping die body has cracks or aluminum adhesion.

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