Thermal fatigue experiment device with constraint and experiment method

Abstract

The invention relates to the technical field of thermal fatigue tests of materials, in particular to a thermal fatigue experimental device with constraint and an experimental method, comprising a base, a high-frequency magnetic induction heating source arranged at the upper part of the base, a console and a base table; a movable frame, a box body and a fixed frame are sequentially arranged on the base table along the same axis, and a movable end groove chuck extending into the box body is arranged at one end of the movable frame; a fixed end groove chuck extending into the box body is arranged at one end of the fixed frame; the movable end groove chuck and the fixed end groove chuck are respectively connected with two ends of a tested sample; the high-frequency magnetic induction heating source is positioned on one side of the base table and is provided with a magnetic induction heating coil extending into the box body, and the magnetic induction heating coil is arranged around the tested sample and is used for heating the tested sample; the device is used for detecting an experiment object in a multi-working-condition state, a tested sample can be rapidly heated and cooled, meanwhile, alternation of cold and heat cycles is simulated, different constraints of the outside world on a workpiece are simulated, and the test has higher accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal fatigue testing of materials, and particularly to a thermal fatigue experimental device with constraints and an experimental method. Background Art

[0002] With the rapid development of industry, the phenomenon of component damage caused by deformation or fracture has become less and less. Instead, the phenomenon of component failure caused by cumulative damage such as thermal fatigue has become more and more. Components working in high-temperature and high-pressure environments for a long time generate a large amount of heat exchange in a short time during the repeated heating and cooling cycles, ultimately resulting in defects in the components, such as cracks. Thermal shock refers to the phenomenon that when a component is rapidly heated and cooled, the temperature changes sharply, and thermal stress will be generated inside the component and change with the temperature, affecting the internal structure of the component. Thermal fatigue is the phenomenon that due to repeated thermal shocks, thermal damage failures frequently occur in components during use. The most representative one is the generation of penetrating cracks on the components.

[0003] For example, a flywheel thermal fatigue testing machine and a method for testing the thermal fatigue performance of a flywheel disclosed in Chinese invention patent CN103245584A include a bench, a flywheel rotation assembly, including an AC motor provided on the bench, and a flywheel fixing table rotatably fitted with the bench and driven by the AC motor; a positioning assembly, including a moving table and a driving mechanism for driving the moving table to change its horizontal and vertical positions; a heating assembly, including a power supply device fixed on the moving table and an induction coil connected to the power supply device for heating the flywheel to be tested; a detection assembly, including a temperature detector for collecting the temperature of the flywheel, and a computer control system for recording the signals transmitted by the temperature detector; a cooling assembly, including a nozzle erected above the flywheel fixing table and a cooling medium pipeline connected to the nozzle, and a control switch is provided on the cooling medium pipeline.

[0004] However, the existing thermal fatigue testing machines have too single a detection object, the cooling temperature of the specimen drops slowly, resulting in a slow overall test process and inaccurate experimental data. At the same time, the thermal fatigue testing machine cannot monitor when cracks appear in the specimen. Also, during the working process of the workpiece, in addition to being subjected to the alternating action of heat and cold cycles, it also bears different constraints from the outside world, and the existing thermal fatigue testing machines cannot simulate the actual working conditions. Summary of the Invention

[0005] I. Technical Problems to be Solved

[0006] In view of the above-mentioned defects existing in the prior art, the present invention particularly provides a constrained thermal fatigue test device and test method, which solve the problems that the existing thermal fatigue testing machine has too single test object, slow cooling temperature drop of the specimen, resulting in slow overall test process and inaccurate experimental data; and the thermal fatigue testing machine cannot monitor when cracks occur in the specimen and cannot simulate the actual working conditions.

[0007] II. Technical Solution

[0008] To solve the above technical problems, the present invention provides a constrained clamping device for a thermal fatigue machine, which includes a machine base, a high-frequency magnetic induction heating source arranged on the upper part of the machine base, a control console and a base table;

[0009] A moving frame, a box body and a fixed frame are successively arranged on the base table along the same axis,

[0010] One end of the moving frame is provided with a mobile end groove chuck extending into the box body;

[0011] One end of the fixed frame is provided with a fixed end groove chuck extending into the box body;

[0012] The mobile end groove chuck and the fixed end groove chuck are respectively connected to both ends of the specimen to be tested;

[0013] The high-frequency magnetic induction heating source is located on one side of the base table and is provided with a magnetic induction heating coil extending into the box body. The magnetic induction heating coil is arranged around the specimen to be tested and is used to heat the specimen to be tested;

[0014] The base table is also provided with a water spray nozzle extending into the box body and used to cool the specimen to be tested;

[0015] A driving component is also arranged between the base table and the control console and is used to drive the moving frame to reciprocate along the same axis where the moving frame and the fixed frame are located;

[0016] The control console is used to control the actions of the high-frequency magnetic induction heating source, the water spray nozzle and the driving component.

[0017] Among them, the specimen to be tested is a strip-shaped metal sheet, and a triangular opening is provided at the middle position.

[0018] Both the fixed end groove chuck and the mobile end groove chuck are provided with connecting grooves and fixing jacks;

[0019] Both ends of the specimen to be tested are inserted into the connecting grooves, and the specimen to be tested is fixed by inserting corresponding pins into the fixing jacks.

[0020] Among them, the driving component includes a driving motor, a transmission lead screw located in the control console, and a lead screw slider connected to the moving frame,

[0021] The base table is also provided with a slide rail corresponding to and cooperating with the moving frame. The driving motor is controlled by the console, and the power is transmitted to the moving frame through the transmission lead screw and the lead screw slider, thereby controlling the reciprocating motion of the moving frame.

[0022] A mechanical sensor is provided between the moving frame and the mobile end groove chuck. The mechanical sensor is connected to the mobile end groove chuck through a transmission shaft. After the console issues a control instruction, the mechanical sensor measures the pressure and tension applied to the test specimen.

[0023] The upper part of the fixed frame is also provided with a support frame, and a temperature sensor for detecting the test specimen is provided on the support frame and extends into the box body.

[0024] A constrained thermal fatigue test method includes the following steps:

[0025] S1: Cut two circles at both ends of the test specimen according to the pin size requirements to form round holes, and cut a triangular opening in the middle position.

[0026] S2: Fix both ends of the test specimen through the fixed mobile end groove chuck and the fixed end groove chuck. During the fixing process, adjust the position of the moving frame for cooperation to complete the placement of the test specimen.

[0027] S3: Control the moving frame through the console to further control the movement of the mobile end groove chuck, apply constraints to the test specimen, and perform real-time measurement through the mechanical sensor to reach the preset state.

[0028] S4: Control the high-frequency magnetic induction heating source through the console to start heating the test specimen, and heat up to the first preset temperature; control the water spray nozzle through the console to cool the test specimen, and cool down to the second preset temperature; cycle the above heating-cooling-heating operations at a preset time interval until cracks appear in the test specimen or the set experimental period ends.

[0029] Among them, in S3, when the actual working condition of the simulation object is in a compression state, control the moving frame to further control the mobile end groove chuck to move towards the fixed end groove chuck direction, thereby applying pressure to the test specimen.

[0030] When the actual working condition of the simulation object is in a tension state, control the moving frame to further control the mobile end groove chuck to move away from the fixed end groove chuck direction, thereby applying tension to the test specimen.

[0031] Among them, in S4, the temperature sensor uses an infrared thermometer to measure the temperature change of the test specimen during the experiment.

[0032] Measure the changes in tension and pressure during the experiment through the mechanical sensor.

[0033] Observe the direction of crack initiation and propagation through a camera with a zoom lens.

[0034] III. Beneficial Effects

[0035] Compared with the prior art, the thermal fatigue testing machine of the present invention can be used to detect experimental objects under multiple working conditions, can quickly heat and cool the test specimen, and at the same time simulate the alternating hot and cold cycles, as well as the compressive state or tensile state, simulating different constraints of the outside world on the workpiece, making the test have higher accuracy. The device of the present invention has a low cost, is easy to operate, and can also replace the style of the clamping chuck to realize the clamping of test specimens of various different sizes and shapes;

[0036] The present invention can stop the test until cracks appear at the notch of the specimen according to the set hot and cold cycle period, heating rate, heating temperature, cooling rate, and hot and cold cycle interval, and can obtain the change of the thermal fatigue life curve of the specimen with different heating temperatures T; by adjusting the hot and cold cycle period, the change of the thermal fatigue limit life curve of the specimen with different cycle periods N can be obtained;

[0037] The present invention can also stop the test until cracks appear at the notch of the specimen according to the set hot and cold cycle period, heating rate, heating temperature, cooling rate, hot and cold cycle interval, the magnitude of the applied binding force, and the duration of the binding force, and can obtain the change of the thermal fatigue life curve of the specimen with different magnitudes of the binding force F; by adjusting the duration of the applied constraint, the change of the thermal fatigue limit life curve of the specimen with different binding force periods N can be obtained. Description of the Drawings

[0038] Figure 1 It is a schematic side structure diagram of the present invention;

[0039] Figure 2 It is a schematic front view structure diagram of the present invention;

[0040] Figure 3 It is a schematic top view structure diagram of the present invention;

[0041] Figure 4 It is a schematic structure diagram of the groove chuck in the present invention;

[0042] Figure 5 It is a schematic structure diagram of the test specimen adapted in the present invention;

[0043] In the figure:

[0044] 1 is the machine base; 2 is the high-frequency magnetic induction heating source; 3 is the control console; 4 is the lead screw; 5 is the moving frame; 6 is the base table; 7 is the fixed frame; 8 is the support frame; 9 is the temperature sensor; 10 is the box body; 11 is the transmission shaft; 12 is the mechanical sensor; 13 is the water spray head; 14 is the fixed-end groove chuck; 15 is the magnetic induction heating coil; 16 is the moving-end groove chuck; 17 is the test specimen; 18 is the pin shaft; 21 is the connecting groove; 22 is the fixed jack; 121 is the triangular opening; 122 is the round hole. Specific embodiments

[0045] The following combines the drawings and embodiments to further describe the specific embodiments of the present invention in detail. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0046] Embodiment 1:

[0047] The present invention provides a constrained thermal fatigue test device and method, and processes the workpiece material to be tested into Figure 5 the test specimen as shown. This test device can detect most metal materials; using the cooling water of the water spray head 13 to cool the test specimen during the experiment can accelerate the cooling time of the test specimen; setting a camera to detect the start time of cracks and issuing an instruction by the control console to abort the test; different constraints can be applied to the test specimen to meet the diversity of thermal fatigue tests, so as to better restore the thermal fatigue performance of the workpiece under the constrained state in actual working conditions.

[0048] To achieve the above purpose, as Figures 1 to 4 shown, the constrained clamping device of the thermal fatigue machine in this embodiment includes a machine base 1, a high-frequency magnetic induction heating source 2, a control console 3 and a base table 6 arranged on the upper part of the machine base 1; on the base table 6, a moving frame 5, a box body 10 and a fixed frame 7 are arranged in sequence along the same axis. One end of the moving frame 5 is provided with a moving-end groove chuck 16 extending into the box body 10; one end of the fixed frame 7 is provided with a fixed-end groove chuck 14 extending into the box body 10;

[0049] The moving-end groove chuck 16 and the fixed-end groove chuck 14 are respectively connected to both ends of the test specimen 17; the high-frequency magnetic induction heating source 2 is located on one side of the base table 6 and is provided with a magnetic induction heating coil 15 extending into the box body 10. The magnetic induction heating coil 15 is arranged around the test specimen 17 and is used to heat the test specimen 17. The test specimen 17 is a strip-shaped metal sheet, and a triangular opening 121 is provided in the middle position;

[0050] The base table 6 is also provided with a water spray head 13 extending into the box body 10 and used to cool the test specimen 17; a water outlet is also provided at the lower end of the base table 6, and the cooling water flowing through the test specimen can be discharged from the water outlet to prevent the device from being corroded and affecting the test accuracy during multiple cyclic experiments.

[0051] A drive assembly is also provided between the base table 6 and the control console 3 for driving the moving frame 5 to reciprocate along the same axis as the moving frame 5 and the fixed frame 7; the control console 3 is used to control the high-frequency magnetic induction heating source 2, the water spray nozzle 13 and the drive assembly to act.

[0052] Both the fixed-end groove chuck 14 and the mobile-end groove chuck 16 are provided with connection grooves 21 and fixing jacks 22; both ends of the test specimen 17 are inserted into the connection grooves 21, and the test specimen 17 is fixed by inserting the corresponding pin shafts 18 into the fixing jacks 22, so that the test specimen 17 will not change its position when being constrained during the test, ensuring the accuracy of the test.

[0053] The drive assembly includes a drive motor, a transmission lead screw 4 located in the control console 3, and a lead screw slider connected to the moving frame 5. A slide rail corresponding to the moving frame 5 is also provided on the base table 6. The drive motor is controlled by the control console 3, and the power is transmitted to the moving frame 5 through the transmission lead screw 4 and the lead screw slider, thereby controlling the reciprocating movement of the moving frame 5.

[0054] A mechanical sensor 12 is provided between the moving frame 5 and the mobile-end groove chuck 16. The mechanical sensor 12 is connected to the mobile-end groove chuck 16 through a transmission shaft 11. After the control console 3 issues a control instruction, the mechanical sensor 12 measures the pressure and tension applied to the test specimen 17, so as to achieve the purpose of applying constraints to the test specimen 17. During the experiment, after receiving the signal transmitted from the control console 3, the constraint force applied to the test specimen 17 is measured, simulating the influence of the workpiece being subjected to tension or pressure under actual conditions, and is transmitted to the display of the control console 3 in digital form.

[0055] A support frame 8 is further provided on the upper part of the fixed frame 7, and a temperature sensor 9 for detecting the test specimen 17 is provided on the support frame 8 and extends into the box body 10.

[0056] A thermal fatigue experiment method with constraints includes the following steps:

[0057] S1: Cut two circles to form round holes 122 at both ends of the test specimen 17 according to the size requirements of the pin shafts 18, and cut a triangular opening 121 at the middle position.

[0058] S2: Fix both ends of the test specimen 17 through the fixed mobile-end groove chuck 16 and the fixed-end groove chuck 14, and cooperate by adjusting the position of the moving frame 5 during the fixing process to complete the placement of the test specimen 17.

[0059] Specifically, one end of the test sample 17 is inserted into the connection groove 21 with the same size as the test sample 17 in the fixed-end groove chuck 14. The pin shaft 18 passes through the fixed jack 22 provided on the outer surface of the fixed-end groove chuck 14 and the circular hole 122 provided on the test sample 17, so that the test sample 17 is fixed in the connection groove 21, and the fixed jack 22 and the circular hole 122 are in concentric fit. Align the connection groove 21 on the mobile-end groove chuck 16 with the connection groove 21 on the fixed-end groove chuck 14 to make the directions of the two connection grooves 21 the same. Move the moving frame 5 with the mobile-end groove chuck 16, and repeat the previous step. Pass the pin shaft 18 through the fixed jack 22 provided on the outer surface of the mobile-end groove chuck 16 and the circular hole 122 provided on the test sample 17, so that the test sample 17 is tightly fitted with the connection groove 21 provided on the mobile-end groove chuck 16, and the preparation work for placing the sample is completed.

[0060] S3: Control the moving frame 5 through the console 3, and then control the movement of the mobile-end groove chuck 16 to apply constraints to the test sample 17, and perform real-time measurement through the mechanical sensor 12 to reach the preset state;

[0061] S4: Control the high-frequency magnetic induction heating source 2 through the console 3 to start heating the test sample 17 until the first preset temperature is reached; control the water spraying nozzle 13 through the console 3 to cool down the test sample 17 until the second preset temperature is reached; cycle the above heating-cooling-heating operations at preset time intervals until cracks appear on the test sample 17 or the set experimental period ends.

[0062] In S3, when the actual working condition of the simulation object is in a compressive state, control the moving frame 5 and then control the mobile-end groove chuck 16 to move towards the fixed-end groove chuck 14, so as to apply pressure to the test sample 17;

[0063] When the actual working condition of the simulation object is in a tensile state, control the moving frame 5 and then control the mobile-end groove chuck 16 to move away from the fixed-end groove chuck 14, so as to apply tensile force to the test sample 17.

[0064] In S4, the temperature sensor 9 uses an infrared thermometer to measure the temperature change of the test sample 17 during the experiment, uses the mechanical sensor 12 to measure the change of tensile force and pressure during the experiment, and observes the direction of crack initiation and propagation through a camera with a variable focal length lens.

[0065] In the present invention, the influence of the alternating action of thermal and cold cycles on the service life of a workpiece can be simulated through the following process: Set the thermal and cold cycle period, heating rate, heating temperature, cooling rate, and thermal and cold cycle interval according to the test requirements respectively until cracks appear at the notch of the specimen and the test stops. Obtain the variation of the thermal fatigue life curve of the specimen with different heating temperatures T; adjust the thermal and cold cycle period to obtain the variation of the thermal fatigue limit life curve of the specimen with different cycle periods N.

[0066] The influence of the alternating action of thermal and cold cycles on the service life of a workpiece under a constrained state can also be simulated through the following process: Set the thermal and cold cycle period, heating rate, heating temperature, cooling rate, thermal and cold cycle interval, the magnitude of the applied constraint force, and the duration of the constraint force according to the test requirements respectively until cracks appear at the notch of the specimen and the test stops. Obtain the variation of the thermal fatigue life curve of the specimen with different magnitudes of the constraint force F; adjust the duration of the applied constraint to obtain the variation of the thermal fatigue limit life curve of the specimen with different constraint force periods N.

[0067] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A thermal fatigue test device with constraints, characterized in that: The belt restraint clamping device for a thermal fatigue machine comprises a machine base (1), a high-frequency magnetic induction heating source (2) arranged on the upper part of the machine base (1), a control console (3) and a base table (6); A movable frame (5), a box (10) and a fixed frame (7) are arranged in sequence on the base platform (6) along the same axis. One end of the movable frame (5) is provided with a movable end groove chuck (16) extending into the box body (10); One end of the fixing frame (7) is provided with a fixing end groove chuck (14) extending into the box body (10); The movable end groove chuck (16) and the fixed end groove chuck (14) are respectively connected to two ends of the test sample (17); The high-frequency magnetic induction heating source (2) is located on one side of the base platform (6) and is provided with a magnetic induction heating coil (15) extending into the box body (10); the magnetic induction heating coil (15) is arranged around the test sample (17) and is used to heat the test sample (17); The base platform (6) is also provided with a water spray nozzle (13) extending into the box body (10) and used for cooling the tested sample (17); A driving assembly is also provided between the base platform (6) and the control console (3) for driving the movable frame (5) to reciprocate along the same axis as the movable frame (5) and the fixed frame (7); The control console (3) is used to control the actions of the high-frequency magnetic induction heating source (2), the water spray nozzle (13) and the driving component.

2. A thermal fatigue test device with constraints according to claim 1, characterized in that: The tested sample (17) is a strip-shaped metal sheet and has a triangular opening (121) in the middle.

3. A thermal fatigue test device with constraints according to claim 2, characterized in that: The fixed end groove chuck (14) and the movable end groove chuck (16) are both provided with a connecting groove (21) and a fixed insertion hole (22); The two ends of the tested sample (17) are inserted into the connection grooves (21), and the tested sample (17) is fixed by inserting the corresponding pin shaft (18) into the fixing plug hole (22).

4. The constrained thermal fatigue test device according to claim 1, characterized in that: The driving assembly comprises a driving motor located in a control console (3), a transmission screw (4), and a screw slider connected to a moving frame (5). The base platform (6) is also provided with a slide rail corresponding to the moving frame (5). The driving motor is controlled by the control console (3) to transmit power to the moving frame (5) through the transmission lead screw (4) and the lead screw slider, thereby controlling the reciprocating motion of the moving frame (5).

5. The constrained thermal fatigue test device according to claim 1, characterized in that: A mechanical sensor (12) is provided between the mobile frame (5) and the mobile end groove chuck (16). The mechanical sensor (12) is connected to the mobile end groove chuck (16) via a transmission shaft (11). After the control console (3) issues a control command, the mechanical sensor (12) measures the pressure and tension applied to the test sample (17).

6. The constrained thermal fatigue test device according to claim 1, characterized in that: A support frame (8) is also provided on the upper part of the fixing frame (7), and a temperature sensor (9) for detecting the test sample (17) is provided on the support frame (8) and extends into the box body (10).

7. A constrained thermal fatigue test method, characterized in that: The thermal fatigue test device with constraints according to any one of claims 1 to 6 comprises the following steps: S1: Cut two circles at both ends of the test sample (17) to form circular holes (122) according to the size requirements of the pin shaft (18), and cut a triangular opening (121) in the middle; S2: Fixing the two ends of the test sample (17) by fixing the movable end groove chuck (16) and the fixed end groove chuck (14), and adjusting the position of the movable frame (5) during the fixing process to complete the placement of the test sample (17); S3: Controlling the moving frame (5) through the control console (3) and then controlling the movement of the groove chuck (16) at the moving end, applying constraints to the test sample (17), and performing real-time measurement through the mechanical sensor (12) to achieve a preset state; S4: Controlling the high-frequency magnetic induction heating source (2) through the control console (3) to start heating the test sample (17), and heating the temperature to a first preset temperature; controlling the water spray nozzle (13) through the control console (3) to cool the test sample (17), and cool the temperature to a second preset temperature; and repeating the above heating-cooling-heating operation at preset time intervals until cracks appear on the test sample (17) or the set experimental cycle ends.

8. A constrained thermal fatigue test method according to claim 7, characterized in that: In S3, when the actual working condition of the simulated object is a pressure state, the movable frame (5) is controlled to further control the movable end groove chuck (16) to move toward the fixed end groove chuck (14), thereby applying pressure to the test sample (17); When the actual working condition of the simulated object is a tension state, the movable frame (5) is controlled to further control the movable end groove chuck (16) to move away from the fixed end groove chuck (14), thereby applying tension to the tested sample (17).

9. A constrained thermal fatigue test method according to claim 7, characterized in that: In S4, the temperature sensor (9) is an infrared thermometer, which measures the temperature change of the test sample (17) during the experiment. The changes of tension and pressure during the experiment are measured by a mechanical sensor (12). The direction of crack initiation and propagation is observed through a camera with a zoom lens.

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