Thermal fatigue test method and equipment with customized thermal cycle period

Abstract

The invention provides a thermal cycle period customized thermal fatigue test method and equipment, the equipment comprises a rotation system, a heating unit, a cooling unit, a temperature detection probe, a temperature detector and a temperature controller, the temperature controller outputs signals to control the rotation system and a temperature adjusting system, thermal and cold circulation of a workpiece is realized, and the thermal fatigue test efficiency is improved. The temperature value of the sample in the whole cycle period is obtained through signal input of the temperature detector, the temperature controller compares the temperature fed back by the temperature detector with the set temperature, then the rotating system, the cooling unit and the heating unit are regulated and controlled and optimized continuously, and fitting of temperature waveforms is achieved. According to the equipment, through cooperative work of the temperature controller, the temperature adjusting system, the temperature detector and the rotating system, temperature control and rotating control on the sample placing platform are realized, so that the thermal fatigue test requirements of the same test material under various working conditions are met.

Description

Technical Field

[0001] The present invention relates to the technical field of test equipment, and particularly to a thermal fatigue test method and equipment with customized thermal cycle periods. Background Art

[0002] Thermal fatigue is one of the main failure forms of hot working dies, especially die-casting dies. Thermal fatigue tests can accurately evaluate the thermal fatigue performance of die materials. By comparing the thermal fatigue performance of different materials, more suitable die materials for specific working conditions can be selected, thereby improving the service life and reliability of the dies.

[0003] However, in current thermal fatigue tests, heating and cooling units with fixed temperature cycling modes are generally used, and the thermal cycle periods are fixed. Only thermal fatigue tests with a single thermal cycle can be carried out, which cannot meet the requirements for thermal fatigue tests of the same test material under multiple working conditions.

[0004] In view of this, the inventor of the present invention has specifically designed a thermal fatigue test method and equipment with customized thermal cycle periods, and this case is thus generated. Summary of the Invention

[0005] In order to solve the above problems, the technical solution of the present invention is as follows:

[0006] A thermal fatigue test equipment with customized thermal cycle periods, comprising

[0007] A rotation system, including a stepper motor, a rotating shaft, and fixed supports provided at both ends. One end of the rotating shaft is fixedly connected to the output end of the stepper motor, and the other end is rotatably connected to the fixed support. The stepper motor is fixedly connected to another fixed support. During the thermal fatigue test, the rotating shaft is used to fix the test material;

[0008] A temperature regulation system, including a heating unit and a cooling unit. The heating unit includes two induction heaters, and the two induction heaters are symmetrically arranged on both sides of the rotating shaft. The cooling unit includes two sets of spray cooling devices, and the two sets of spray cooling devices are symmetrically arranged on the upper and lower sides of the rotating shaft;

[0009] A temperature detection system, including a temperature detection probe and a temperature detector. The temperature detection probe is embedded inside the test material, and the temperature detector is electrically connected to the temperature detection probe by a wire;

[0010] A temperature controller, which is electrically connected to the stepper motor, the induction heater, the spray cooling device, and the temperature detector respectively; the temperature controller is used to set the target temperature-time waveform, receive the temperature feedback signal from the temperature detector, and output control commands for the stepper motor, the induction heater, and the spray cooling device.

[0011] Preferably, the rotation system further includes a motor controller and a cycle counter. The motor controller is used to control the rotation speed and direction of the stepper motor. The cycle counter is electrically connected to the motor controller and the temperature controller.

[0012] Preferably, one end of the rotating shaft is connected to the output end of the stepper motor through a coupling. A sleeve assembly is sleeved on the other end of the rotating shaft. The sleeve assembly is detachably connected to the rotating shaft, and one end of the sleeve assembly is fixedly connected to the fixed support.

[0013] Preferably, the sleeve assembly includes a sleeve body and a spring ballast mechanism. The sleeve body is fixedly connected to the spring ballast mechanism. The spring ballast mechanism includes a ballast spring and gaskets provided at both ends of the ballast spring. The sleeve body, the gaskets and the ballast spring are sleeved on the rotating shaft. One end of the gasket is connected to the ballast spring, and the other end is connected to the fixed support.

[0014] Preferably, a flat key is provided on the rotating shaft. The test material is cylindrical, and a keyway is provided on the inner cylindrical surface of the test material. The keyway cooperates with the flat key on the rotating shaft, and the test material is sleeved on the rotating shaft.

[0015] Preferably, the diameter of the rotating shaft is 19.99 mm - 20.01 mm;

[0016] The surface roughness of the rotating shaft is 0.5 μm - 1.5 μm;

[0017] The outer diameter of the sleeve body is 29.9 mm - 30.1 mm, and the inner diameter is 20.01 mm - 20.02 mm;

[0018] The surface roughness of the sleeve body is 0.5 μm - 1.5 μm;

[0019] The width of the flat key is 2.8 mm - 3.2 mm, the height is 4.8 mm - 5.2 mm, and the length is 4.8 mm - 5.2 mm.

[0020] Preferably, the induction heater has an arc-shaped heating head, and the cross-section thereof is a partial circumferential arc segment of a hollow cylinder. The cross-section of the arc-shaped heating head is a minor arc and is located at the same position as the center of the rotating shaft. The arc surface of the arc-shaped heating head is parallel to the surface of the material to be tested. A partition is provided between the heating unit and the cooling unit, and the installation angle of the partition forms an angle of 30° - 60° with the rotation axis of the rotating shaft.

[0021] Preferably, the geometric parameters of the arc-shaped heating head satisfy:

[0022] The distance between the two end planes is 25 mm - 30 mm;

[0023] The degree of the central angle corresponding to the cross-section of the arc-shaped heating head is 70°-90°;

[0024] The diameter of the circle where the inner arc of the cross-section of the arc-shaped heating head is located is 41mm-42mm;

[0025] The vertical distance between the arc-shaped housing of the arc-shaped heating head and the surface of the material to be measured is 1mm-2mm;

[0026] The present invention also discloses a test method for a thermal fatigue device with customized thermal cycle periods. The steps of this method include:

[0027] S1. According to the temperature cycle state suffered by the test material under the target working conditions, design the temperature cycle curve changing with time and the cycle period, and input it into the temperature controller for signal output;

[0028] S2. Design and preparation of the test material size;

[0029] S3. Installation of the test material and the temperature detection probe;

[0030] S4. Conduct a preliminary experiment. Through the temperature controller, the process parameters of the heating unit and the cooling unit are adjusted in real time. First, perform rough shaping to make the fitting degree of the temperature-time waveform and the preset waveform reach 80%, and then perform fine shaping to make the fitting degree of the temperature-time waveform and the preset waveform reach 97%. End the experiment and export the data;

[0031] S5. Formal experiment. According to the data obtained from the preliminary experiment, start the formal experiment. Repeat the experiment 3-5 times with 3-5 different specimens to ensure the reliability of the experiment;

[0032] S6. At the end of the experiment, turn off the heating unit, keep the stepping motor and the cooling unit running to cool the specimen to room temperature. Stop the stepping motor, turn off the cooling unit, and remove the specimen;

[0033] S7. Perform ultrasonic cleaning on the specimen;

[0034] S8. Analyze the thermal fatigue performance of the processed sample, including the crack density of the surface thermal fatigue crack, the average depth of the thermal fatigue crack, the microhardness distribution in the transverse and depth directions, etc.

[0035] The technical solution provided by the present invention has the following beneficial effects:

[0036] 1. The present invention controls the rotation system and the temperature regulation system through the output signal of the temperature controller to realize the cold and hot cycle of the workpiece. By inputting the signal of the temperature detector, the temperature value of the specimen during the entire cycle period is obtained. The temperature controller compares the temperature feedback from the temperature detector with the set temperature, and then regulates the rotation system, the cooling unit, and the heating unit, and continuously optimizes to achieve the fitting of the temperature waveform. Through the coordinated work of the temperature controller, the temperature regulation system, the temperature detector, and the rotation system, the present invention realizes the temperature control and rotation control of the specimen placement platform, thereby meeting the thermal fatigue test requirements of the same test material under various working conditions.

[0037] 2. By placing the wired temperature detection probe in the test material, the present invention avoids the influence of water vapor during temperature detection and improves the accuracy of the measured temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0039] Wherein:

[0040] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0041] Figure 2 is a logic diagram of the thermal fatigue device;

[0042] Figure 3 is a schematic diagram of the sleeve assembly structure;

[0043] Figure 4 is a flowchart of a thermal fatigue test method with customized thermal cycle period according to the present invention;

[0044] Figure 5 is a schematic diagram of a partial temperature-time waveform that can be realized in the present invention;

[0045] Figure 6 is a surface diagram of the test material before the test of the present invention;

[0046] Figure 7 is a surface diagram of the test material after the test of the present invention.

[0047] Label Description:

[0048] 1. Rotating system; 11. Stepping motor; 12. Rotating shaft; 13. Fixed support; 14. Motor controller; 15. Cycle counter; 16. Coupling; 17. Sleeve assembly; 171. Sleeve body; 172. Spring ballast mechanism; 173. Ballast spring; 174. Gasket; 18. Flat key; 2. Temperature regulation system; 21. Heating unit; 22. Cooling unit; 23. Induction heater; 24. Spray cooling device; 25. Curved surface heating head; 3. Temperature detection system; 31. Temperature detection probe; 32. Temperature detector; 4. Temperature controller; 5. Partition board. Detailed implementation manner

[0049] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] Please refer to Figures 1 to 7 , which is a thermal fatigue test device with customized thermal cycle periods as the best embodiment of the present invention, and includes:

[0051] Rotating system 1, including a stepping motor 11, a rotating shaft 12 and fixed supports 13 provided at both ends. One end of the rotating shaft 12 is fixedly connected to the output end of the stepping motor 11, and the other end is rotatably connected to the fixed support 13. The stepping motor 11 is fixedly connected to the other fixed support 13. During the thermal fatigue test, the rotating shaft 12 is used to fix the test material; during the thermal fatigue test, the rotating shaft 12 is used to fix the test material. The stepping angle of the stepping motor 11 is 1.8°, ensuring a small rotational positioning error of the specimen at high temperatures;

[0052] Temperature regulation system 2, including a heating unit 21 and a cooling unit 22. The heating unit 21 includes two induction heaters 23, and the two induction heaters 23 are symmetrically arranged on both sides of the rotating shaft 12. The cooling unit 22 includes two sets of spray cooling devices 24, and the two sets of spray cooling devices 24 are symmetrically arranged on the upper and lower sides of the rotating shaft 12. The power range of the induction heater 23 is 200 - 2500W, and the spray cooling device 24 is a flat nozzle water spray, and the spray water flow rate can be adjusted between 0 - 30L / min. Among them, the heating unit 21 is provided with a heating controller, and the cooling unit 22 is provided with a cooling controller;

[0053] The temperature detection system 3 includes a temperature detection probe 31 and a temperature detector 32. The temperature detection probe 31 is embedded inside the test material. The temperature detector 32 is connected to the temperature detection probe 31 by wires. The temperature detector 32 is used to receive the monitoring data of the temperature detection probe 31 and then transmit the data to the temperature controller 4 in the form of an electrical signal. A small hole with a diameter of 0.5 mm and a depth of half of the width of the specimen is drilled at a position 1 mm away from the surface layer of the specimen, and then the temperature detection probe 31 is embedded. The temperature detection probe 31 uses a platinum-rhodium thermocouple with an operating temperature range of 20 - 1000 °C. At the same time, the temperature detection probe 31 is a wired probe. The rotating device rotates one week clockwise and then one week counterclockwise, and keeps circulating, without affecting the position of the wires. The thermal fatigue experiment using the water-cooling method to achieve cooling circulation will form random and unstable thermal steam clusters around the specimen. The formation of this thermal steam cluster will interfere with the temperature measurement of the non-contact high-temperature recorder, resulting in an error of about 50 °C in the measured temperature. While the embedded detection can avoid the influence of water vapor during the detection process and improve the accuracy of the measured temperature.

[0054] The temperature controller 4 is electrically connected to the stepping motor 11, the induction heater 23, the spray cooling device 24, and the temperature detector 32 by electrical signals respectively. The temperature controller 4 is used to set the target temperature-time waveform, receive the temperature feedback signal from the temperature detector, and output the control commands for the stepping motor 11, the induction heater 23, and the spray cooling device 24. Among them, the temperature controller 4, the heating controller, the cooling controller, and the temperature detector 32 are integrated in the central integration cabinet. The working logic relationship of this equipment is as follows:

[0055] The signal output by the temperature controller 4 controls the rotating system 1, the cooling unit 22, and the heating unit 21 to realize the cold and hot cycling of the workpiece. Through the signal input of the temperature detector 32, the temperature values of the specimen during the entire cycling period are obtained. The temperature controller 4 compares the temperature fed back by the temperature detector 32 with the set temperature, and then regulates the rotating system 1, the cooling unit 22, and the heating unit 21, and continuously optimizes to realize the fitting of the temperature waveform. This equipment realizes the temperature control and rotation control of the specimen placement platform through the coordinated work of the temperature controller 4, the cooling unit 22, the heating unit 21, the temperature detector 32, and the rotating system 1, so as to meet the thermal fatigue test requirements of the same test material under various working conditions.

[0056] Specifically, please refer to Figures 1 to 3, the rotation system 1 further includes a motor controller 14 and a cycle counter 15. The motor controller 14 is used to control the rotation speed and direction of the stepping motor 11. The cycle counter 15 is electrically connected to the motor controller 14 and the temperature controller 4. By setting different cycle numbers on the cycle counter 15, different signals are given to the motor controller 14, so as to achieve the effects of different periods. Through the signal linkage between the temperature controller 4 and the cycle counter 15, the temperature-rotation period coordinated control can be realized. The cycle counter 15 records the number of completed cycles in real time and stores it synchronously with the temperature data. When the actual cycle number is close to the set value, the system will give an automatic warning to avoid overloading the test.

[0057] Specifically, please refer to Figures 1 to 3 , one end of the rotating shaft 12 is connected to the output end of the stepping motor 11 through a coupling 16. A sleeve assembly 17 is sleeved on the other end of the rotating shaft 12. The sleeve assembly 17 is detachably connected to the rotating shaft 12. One end of the sleeve assembly 17 is fixedly connected to the fixed support 13. The sleeve assembly 17 can prevent the test material from moving along the direction of the rotating shaft 12. One end of the rotating shaft 12 is connected to the output end of the stepping motor 11 through a coupling 16. This coupling 16 connection method itself also has a certain degree of flexibility. The coupling 16 can be selected and adjusted according to different models of the stepping motor 11 and the size of the output shaft. Since the sleeve assembly 17 is detachably connected to the rotating shaft 12, when the sleeve assembly 17 is worn, damaged, or needs to be cleaned, maintained, etc., it can be easily removed from the rotating shaft 12.

[0058] Specifically, please refer to Figure 3 , the sleeve assembly 17 includes a sleeve body 171 and a spring ballast mechanism 172. The sleeve body 171 is fixedly connected to the spring ballast mechanism 172. The spring ballast mechanism 172 includes a ballast spring 173 and gaskets 174 provided at both ends of the ballast spring 173. The sleeve body 171, the gaskets 174, and the ballast spring 173 are sleeved on the rotating shaft 12. One end of the gasket 174 is connected to the ballast spring 173, and the other end is connected to the fixed support 13. The spring ballast mechanism 172 generates an elastic force through the ballast spring 173, and the gaskets 174 at both ends evenly transfer the elastic force of the spring to the sleeve body 171 and the rotating shaft 12, so as to apply a stable pre-tightening force to the sleeve assembly 17, making the test material more stable and not moving along the direction of the rotating shaft 12.

[0059] Specifically, please refer to Figure 3, a flat key 18 is provided on the rotating shaft 12. The test material is cylindrical, and a keyway is provided on the inner cylindrical surface of the test material. The keyway is in transitional fit with the flat key 18 on the rotating shaft 12. The test material is sleeved on the rotating shaft 12. The fit between the flat key 18 and the keyway can ensure that the rotational motion and torque of the rotating shaft 12 can be accurately transmitted to the test material. The side surface of the flat key 18 is in close fit with the keyway, forming a rigid connection, so that the torque can be efficiently transmitted between the two, thereby improving the accuracy and repeatability in the test process. The rotational motion of the test material is more stable, reducing the test errors caused by connection looseness or slipping.

[0060] For details, please refer to Figures 1 to 3 , the diameter of the rotating shaft 12 is 19.99 mm - 20.01 mm;

[0061] The surface roughness of the rotating shaft 12 is 0.5 μm - 1.5 μm;

[0062] The outer diameter of the sleeve body 171 is 29.9 mm - 30.1 mm, and the inner diameter is 20.01 mm - 20.02 mm;

[0063] The surface roughness of the sleeve body 171 is 0.5 μm - 1.5 μm;

[0064] The width of the flat key 18 is 2.8 mm - 3.2 mm, the height is 4.8 mm - 5.2 mm, and the length is 4.8 mm - 5.2 mm;

[0065] In this embodiment, the diameter of the rotating shaft 12 is 20 mm; through the flat key 18, it can be in transitional fit with the test material. The surface roughness of the rotating shaft 12 is 1 μm; the outer diameter of the sleeve body 171 is 30 mm, and the inner diameter is 20.02 mm; when heating in the heating unit, the test material can be heated evenly. The surface roughness of the sleeve body 171 is 1 μm; the width of the flat key 18 is 3 mm, the depth is 5 mm, and the height is 5 mm; the fit with the keyway ensures assembly, precise transmission, and coaxial transmission with the rotating shaft 12. The rotating shaft 12 is in transitional fit with the inner hole of the specimen material, ensuring the axial fixation of the specimen material and the radial thermal expansion is not restricted. At the same time, the surface roughness is 1 μm, and the contact surface roughness ≤ 1.6 μm, which can reduce the friction loss and improve the torque transmission efficiency.

[0066] At the same time, the parameters of the test material used in the present invention should meet:

[0067] The inner hole diameter is 20.01 mm - 20.02 mm, and the inner cylindrical surface roughness is 9 μm - 11 μm;

[0068] The outer surface diameter is 39.99 mm - 40.01 mm, and the outer cylindrical surface roughness is 0.5 μm - 1.5 μm;

[0069] The test width of the specimen is 10 mm - 20 mm. The width range of 10 - 20 mm adapts to different thermal gradient requirements. At the same time, if the width is too small, the final result will be accidental and uncertain.

[0070] The width of the keyway is 3.21 mm - 3.31 mm, the depth is 5.21 mm - 5.31 mm, and the height is 5.21 mm - 5.31 mm. It fits better with the flat key 18. In this embodiment, the inner hole diameter is 20.02 mm, and the surface roughness of the inner cylindrical surface is 10 μm, which can cooperate with the rotating shaft 12 to ensure precise transmission and reduce fretting wear. In this embodiment, the keyway parameter width is 3.25 mm, the depth is 5.25 mm, the height is 5.25 mm, the outer surface diameter is 40 mm, and the surface roughness of the outer cylindrical surface is 1 μm, which can enhance the heat radiation efficiency and improve the temperature response.

[0071] Specifically, please refer to Figure 1 , the induction heater 23 has an arc-shaped heating head 25, the cross-section of which is a partial circumferential arc segment of a hollow cylinder. The cross-section of the arc-shaped heating head 25 is a minor arc and is located at the same position as the center of the rotating shaft 12. The arc-shaped shell of the arc-shaped heating head 25 is arranged parallel to the surface of the material to be tested. A partition 5 is provided between the heating unit 21 and the cooling unit 22. The installation angle of the partition 5 forms an angle of 30° - 60° with the rotation axis of the rotating shaft 12. In this embodiment, the installation angle of the partition 5 forms an angle of 45° with the rotation axis of the rotating shaft 12 to prevent cross-interference. The partition 5 separates the heating unit 21 and the cooling unit 22 to prevent mutual influence during heating and cooling, thereby affecting the speed of temperature control.

[0072] Specifically, please refer to Figure 1 , in this embodiment, the geometric parameters of the arc-shaped heating head 25 satisfy:

[0073] The plane distance between the two ends is 27.69 mm, which can ensure that the test material is heated evenly and sufficiently during heating.

[0074] The degree of the central angle corresponding to the cross-section of the arc-shaped heating head 25 is 80°, which increases the size of the heating area and can ensure uniform heating of the test material.

[0075] The diameter of the inner arc of the cross-section of the arc-shaped heating head 25 is 41.5 mm.

[0076] The vertical distance between the arc-shaped shell of the arc-shaped heating head 25 and the surface of the material to be tested is 1.5 mm. The arc surface and the distance from the material surface can ensure that the points on the heating arc surface to the heating points of the material are the same, ensuring heating uniformity.

[0077] The design of the spherical heating head 25 enables the heating head to closely fit the surface of the test material, ensuring uniform heat transfer. At the same time, the contact area between the heating head and the test material is further optimized, enabling the heat to be more evenly distributed and avoiding local overheating or insufficient heating.

[0078] See Figures 1 to 7 As shown, the second aspect of the embodiments of the present application further provides a thermal fatigue test method with customized thermal cycle periods, using the thermal fatigue test device of any of the above embodiments. Specifically, the thermal fatigue test method includes the following steps:

[0079] S1. According to the temperature cycle state of the test material under the target working conditions, design the temperature cycle curve varying with time and the cycle period, and input it into the temperature controller 4 for signal output. The temperature-time curves that can be achieved by the invention include but are not limited to various standard function waveforms and free spline curves. The preset waveform diagrams can be as Figure 5 shown;

[0080] S2. Design and preparation of the test material size. According to the content described in the equipment introduction part of the present invention, design and prepare the samples used in the experiment within the required sample size range;

[0081] S3. Installation of the test material and the temperature detection probe 31. First, put the specimen on the motor end, make the keyway position of the inner hole of the specimen match the position of the flat key 18 of the rotating shaft 12, then install the spring ballast device to complete the fixation of the specimen, and insert the platinum-rhodium thermocouple into the reserved small hole. Before the experiment, turn on the thermocouple to observe whether the temperature is stable at room temperature to judge whether the platinum-rhodium thermocouple is installed correctly;

[0082] S4. Conduct a preliminary experiment. Through the temperature controller 4, adjust the process parameters of the heating unit 21 and the cooling unit 22 in real time, perform two groups of waveform fittings for the actual temperature curve, namely rough shaping and fine shaping. Control the cooling unit 22 and the heating unit 21 to adjust the temperature through the temperature controller 4, and then transmit the real-time temperature signal to the temperature controller 4 through the temperature detector 32, and repeat the adjustment. First, perform rough shaping, so that the fitting degree of the temperature-time waveform and the preset waveform reaches 80%, and then perform fine shaping, so that the fitting degree of the temperature-time waveform and the preset waveform reaches 97%. End the experiment and export the data; when the waveform fitting rate reaches 97%, keep the parameter combination running stably for more than 5 minutes. End the experiment and record the process parameter combination of the temperature controller 4 under the stable operation condition with a fitting degree of 97% for the formal experiment;

[0083] S5. Formal experiment. According to the data obtained from the preliminary experiment, start the formal experiment. Under each temperature cycle state and cycle period condition, repeat the experiment 3 times with 3 different specimens to ensure the reliability of the experiment;

[0084] S6. At the end of the test, turn off the heating unit 21, keep the stepping motor 11 and the cooling unit 22 running to cool the specimen to room temperature. Stop the operation of the stepping motor 11, turn off the cooling unit 22, and remove the specimen;

[0085] S7. Ultrasonically clean the specimen (frequency 30KHZ, time 10min). Perform a light polishing treatment on the surface to be analyzed. The initial grit size of the sandpaper should be higher than European standard P2000. Subsequently, polish to a mirror finish to 1μm;

[0086] S8. Analyze the thermal fatigue performance of the processed sample, such as Figure 6 and Figure 7 , including the crack density of surface thermal fatigue cracks, the average depth of thermal fatigue cracks, the microhardness distribution in the transverse and depth directions, etc.

[0087] Figure 6 This is the surface of the specimen before the test. The surface hardness of the specimen is 743HV1. It can be seen that the surface of the material is relatively flat, with only a small amount of vertical and fine scratches or impurities. There are no obvious cracks or signs of damage, indicating that the integrity of the material surface before the thermal fatigue experiment is good.

[0088] Figure 7 This is the surface of the specimen after the test. The surface hardness of the specimen is 520HV1. It can be seen that obvious turtle-shell-shaped thermal fatigue crack networks appear on the specimen after 1500 cycles of testing. The crack propagation shows multi-directionality, indicating that the specimen is affected by thermal stresses in the transverse and longitudinal directions during the thermal fatigue experiment. The surface hardness of the specimen decreases significantly (by about 30%) after the thermal fatigue experiment, indicating that obvious over-tempering effects occur in the surface layer material during the thermal cycle, resulting in changes in the microstructure of the surface layer material.

[0089] The present invention controls the rotation system 1 and the temperature regulation system 2 by the signal output of the temperature controller 4 to realize the cold and hot cycle of the workpiece. Through the signal input of the temperature detector 32, the temperature value of the specimen during the entire cycle is obtained. The temperature controller 4 compares the temperature fed back by the temperature detector 32 with the set temperature, and then regulates the rotation system 1, the cooling unit 22, and the heating unit 21, and continuously optimizes to realize the fitting of the temperature waveform. This device realizes the temperature control and rotation control of the specimen placement platform through the coordinated work of the temperature controller 4, the temperature regulation system 2, the temperature detector 32, and the rotation system 1, so as to meet the thermal fatigue test requirements of the same test material under various working conditions.

[0090] The present invention has been described exemplarily in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A thermal fatigue test device with customized thermal cycle periods, characterized in that, Comprising: A rotating system (1), including a stepping motor (11), a rotating shaft (12) and fixed supports (13) provided at both ends. One end of the rotating shaft (12) is fixedly connected to the output end of the stepping motor (11), and the other end is rotatably connected to the fixed support (13). The stepping motor (11) is fixedly connected to the other fixed support (13). During the thermal fatigue test, the rotating shaft (12) is used to fix the test material; A temperature regulation system (2), including a heating unit (21) and a cooling unit (22). The heating unit (21) includes two induction heaters (23), and the two induction heaters (23) are symmetrically arranged on both sides of the rotating shaft (12). The cooling unit (22) includes two sets of jet cooling devices (24), and the two sets of jet cooling devices (24) are symmetrically arranged on the upper and lower sides of the rotating shaft (12); A temperature detection system (3), including a temperature detection probe (31) and a temperature detector (32). The temperature detection probe (31) is embedded inside the test material, and the temperature detector (32) is wire-connected to the temperature detection probe (31); A temperature controller (4), which is electrically connected to the stepping motor (11), the induction heater (23), the jet cooling device (24) and the temperature detector (32) respectively. The temperature controller (4) is used to set the target temperature-time waveform, receive the temperature feedback signal from the temperature detector and output control commands for the stepping motor (11), the induction heater (23) and the jet cooling device (24).

2. The customized thermal fatigue test equipment with a thermal cycle period according to claim 1, characterized in that, The rotating system (1) further includes a motor controller (14) and a cycle counter (15). The motor controller (14) is used to control the rotation speed and rotation direction of the stepping motor (11), and the cycle counter (15) is electrically connected to the motor controller (14) and the temperature controller (4).

3. A thermal fatigue test device with customized thermal cycle period according to claim 1, characterized in that, One end of the rotating shaft (12) is connected to the output end of the stepping motor (11) through a coupling (16). A sleeve assembly (17) is sleeved on the other end of the rotating shaft (12). The sleeve assembly (17) is detachably connected to the rotating shaft (12), and one end of the sleeve assembly (17) is fixedly connected to the fixed support (13).

4. A thermal fatigue test device with customized thermal cycle periods according to claim 3, characterized in that, The sleeve assembly (17) includes a sleeve body (171) and a spring ballast mechanism (172). The sleeve body (171) is fixedly connected to the spring ballast mechanism (172). The spring ballast mechanism (172) includes a ballast spring (173) and gaskets (174) provided at both ends of the ballast spring (173). The sleeve body (171), the gasket (174) and the ballast spring (173) are sleeved on the rotating shaft (12). One end of the gasket (174) is connected to the ballast spring (173), and the other end is connected to the fixed support (13).

5. A thermal fatigue test device with customized thermal cycle periods according to claim 1, characterized in that, A flat key (18) is provided on the rotating shaft (12). The test material is cylindrical, and a keyway is provided on the inner cylindrical surface of the test material. The keyway cooperates with the flat key (18) on the rotating shaft (12), and the test material is sleeved on the rotating shaft (12).

6. A customized thermal fatigue test device for thermal cycle periods according to claim 5, characterized in that the diameter of the rotating shaft (12) is 19.99 mm - 20.01 mm; the surface roughness of the rotating shaft (12) is 0.5 μm - 1.5 μm; the outer diameter of the sleeve body (171) is 29.9 mm - 30.1 mm, and the inner diameter is 20.01 mm - 20.02 mm; the surface roughness of the sleeve body (171) is 0.5 μm - 1.5 μm; the width of the flat key (18) is 2.8 mm - 3.2 mm, the height is 4.8 mm - 5.2 mm, and the length is 4.8 mm - 5.2 mm.

7. A thermal fatigue test device with customized thermal cycle period according to claim 5, characterized in that, The induction heater (23) has an arc-shaped heating head (25), and the cross-section thereof is a partial circumferential arc segment of a hollow cylinder. The cross-section of the arc-shaped heating head (25) is a minor arc and is located at the same position as the center of the rotating shaft (12). The arc-shaped housing of the arc-shaped heating head (25) is arranged parallel to the surface of the material to be tested. A partition plate (5) is provided between the heating unit (21) and the cooling unit (22), and the installation angle of the partition plate (5) forms an angle of 30° - 60° with the rotation axis of the rotating shaft (12).

8. A thermal fatigue test device with customized thermal cycle periods according to claim 7, characterized in that, The geometric parameters of the arc-shaped heating head (25) satisfy: the distance between the two end planes is 25 mm - 30 mm; the degree of the central angle corresponding to the cross-section of the arc-shaped heating head (25) is 70° - 90°; the diameter of the circle where the inner arc of the cross-section of the arc-shaped heating head (25) is located is 41 mm - 42 mm; the vertical distance between the arc-shaped housing of the arc-shaped heating head (25) and the surface of the material to be tested is 1 mm - 2 mm.

9. The test method of a thermal fatigue device with customized thermal cycle period according to any one of claims 1-8, characterized in that, The steps of this method include: S1. According to the temperature cycle state suffered by the test material under the target working conditions, design the temperature cycle curve and cycle period changing with time, and input them into the temperature controller (4) for signal output; S2. Design and prepare the size of the test material; S3. Install the test material and the temperature detection probe (31); S4. Conduct a preliminary experiment. Through the temperature controller (4), the process parameters of the heating unit (21) and the cooling unit (22) are adjusted in real time. First, perform rough shaping to make the fitting degree of the temperature-time waveform and the preset waveform reach 80%, and then perform fine shaping to make the fitting degree of the temperature-time waveform and the preset waveform reach 97%. End the experiment and export the data; S5. Conduct a formal experiment. According to the data obtained from the preliminary experiment, start the formal experiment, and repeat the experiment 3 - 5 times with 3 - 5 different specimens to ensure the reliability of the experiment; S6. When the experiment ends, turn off the heating unit (21), keep the stepping motor (11) and the cooling unit (22) running to cool the specimen to room temperature, stop the stepping motor (11) from working, turn off the cooling unit (22), and remove the specimen; S7. Conduct ultrasonic cleaning on the specimen; S8. Conduct a thermal fatigue performance analysis on the processed samples, including the crack density of surface thermal fatigue cracks, the average depth of thermal fatigue cracks, and the microhardness distribution in the transverse and depth directions.

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