A dynamic hardness testing system and a dynamic hardness testing method thereof

Abstract

The application discloses a dynamic hardness testing system and a dynamic hardness testing method thereof, and belongs to the field of material dynamic mechanics experiments.The dynamic hardness testing system comprises a supporting frame, a loading rod slidingly arranged on the supporting frame, a microscope fixedly installed on the supporting frame, a loading device located at the stress end side of the loading rod and a mounting frame located at the force applying end side of the loading rod, wherein a hardness tester pressure head is installed at the force applying end, the loading rod is limited at a loading position through a limiting structure, at the loading position, the top end of the hardness tester pressure head and the focal plane of the objective lens of the microscope are located at the same plane, the mounting frame is arranged on a moving platform, and the sample on the mounting frame can be moved to the plane and the top end of the hardness tester pressure head through the moving platform.The application can determine that the sample reaches the focal plane of the objective lens through moving the sample and using the microscope, and can move the sample from the focal plane of the objective lens to the top end of the hardness tester pressure head, so that it can be determined that the sample just contacts the top end of the hardness tester pressure head, and the installation precision of the sample is ensured.

Description

Technical Field

[0001] This invention relates to the field of dynamic mechanical experiments on materials, and in particular to a dynamic hardness testing system and a dynamic hardness testing method thereof. Background Technology

[0002] Hardness is often used to characterize a material's resistance to indentation deformation, reflecting its yield strength, strain hardening capacity, or the strength of interatomic bonds. Traditional hardness testing can characterize the mechanical properties of materials under quasi-static conditions, but the strain rate effect of materials has been confirmed, making it inaccurate to use hardness indices under quasi-static conditions to describe the mechanical properties of materials under dynamic loading conditions.

[0003] Based on the traditional Hopkinson test apparatus, a dynamic hardness testing system established according to the single-pulse loading principle can realize dynamic hardness testing of materials under medium-to-high strain rate conditions. However, in actual testing, it was found that the traditional dynamic hardness testing device has the problem of sample installation accuracy. Specifically, before dynamic hardness testing, the sample should be in just contact with the hardness tester indenter. If the distance between the two is too large, the indenter cannot reach the sample during loading, or the loading force is less than the set range, resulting in poor repeatability of experimental results. If the sample surface is placed too close to the indenter to ensure the success rate of loading, it will lead to preloading or gaps between the loading rod flange and the sleeve, resulting in secondary loading.

[0004] Existing patent literature discloses dynamic testing schemes for indentation or hardness. For example, Chinese patent application publication number CN108072579A discloses a variable-rate impact indentation testing device and method, including a servo motor drive unit, a pulley transmission unit, a worm gear transmission unit, an electromagnetic clutch control unit, a pendulum motion unit, an impact rod support detection unit, and an observation unit. The servo motor drive unit and the pulley transmission unit are connected to a small pulley. The pulley transmission unit is connected to the worm gear transmission unit, and the worm gear of the worm gear transmission unit is placed on the transmission main shaft II. The pendulum sleeve is connected to the main shaft I, and the pendulum motion unit strikes the impact rod of the impact rod support detection unit to complete the movement. This scheme discloses a loading method that uses a pendulum to strike the impact rod, and the specimen is placed at the specimen support seat by a specimen clamping pin. However, how to determine the relative position of the impact rod and the specimen is not described, and the installation accuracy of the specimen and the impact rod is still a problem.

[0005] For example, Chinese patent application CN 115046874A discloses a method for testing the dynamic hardness of a coating. The dynamic hardness testing apparatus includes a pneumatic control mechanism, a bullet, a waveform shaper, an incident rod, a resistive strain gauge, an indenter, a sample, a piezoelectric sensor, a support, and a computer. During testing, the sample is placed on the piezoelectric sensor, making light contact with the indenter. By controlling different bullet loading speeds, the bullet impacts the incident rod, causing the indenter at the end of the rod to apply varying loading forces to the sample surface. The loading forces are recorded by the computer. This method only provides a general description of the testing procedure. The description of the sample making light contact with the indenter is not readily apparent to the naked eye at a microscopic level; that is, how the sample mounting accuracy is guaranteed is not disclosed.

[0006] Therefore, ensuring the installation accuracy of the sample is a technical problem that urgently needs to be solved in dynamic hardness testing. Summary of the Invention

[0007] The purpose of this invention is to provide a dynamic hardness testing system and method to solve the problems existing in the prior art. By aligning the focal plane of the microscope objective lens with the top of the hardness tester indenter on the same plane, and moving the sample via a moving platform, the microscope can be used to determine when the sample reaches the focal plane of the objective lens. Simultaneously, the moving platform can be used to move the sample from the focal plane of the objective lens to the top of the hardness tester indenter, thereby ensuring that the sample is in contact with the top of the hardness tester indenter and guaranteeing the installation accuracy of the sample.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] This invention provides a dynamic hardness testing system, including a support frame, a loading rod slidably disposed on the support frame, a microscope fixedly mounted on the support frame, a loading device located on the force-bearing end side of the loading rod, and a mounting frame located on the force-applying end side of the loading rod. A hardness tester indenter is mounted on the force-applying end. The loading rod is limited to a loading position by a limiting structure. At the loading position, the top of the hardness tester indenter is on the same plane as the focal plane of the objective lens of the microscope. The mounting frame is disposed on a moving platform, and the sample on the mounting frame can be moved to the plane and the top of the hardness tester indenter via the moving platform.

[0010] Preferably, the objective lens and the hardness tester indenter are located at the same height, and the moving platform includes a Y-axis slide rail parallel to the axis of the loading rod and an X-axis slide rail parallel to the plane.

[0011] Preferably, the limiting structure includes a mass block mounted on the support frame and a sleeve sleeved on the loading rod. The force-bearing end is provided with a flange. At the loading position, one end of the sleeve is attached to the flange and the other end is attached to the mass block.

[0012] Preferably, the loading device employs an electromagnetic loading system, which includes a gun barrel and an induction coil sleeved on the gun barrel. The gun barrel is used to hold bullets, and the outlet of the gun barrel is directly opposite the force-bearing end.

[0013] Preferably, the induction coil includes a common terminal and several terminals, each position of the rotary switch is connected to the terminals, the common terminal of the rotary switch is connected to the common terminal of the induction coil, a capacitor bank is connected in series between the common terminal of the rotary switch and the common terminal of the induction coil, and a charging control module is connected in parallel between the capacitor bank and the common terminal of the induction coil.

[0014] Preferably, the flange, the loading rod, the sleeve, and the mass block are all made of the same material and cannot be magnetized; the length of the loading rod is greater than twice the length of the bullet; and the mass block has a mass greater than twice the sum of the masses of the flange, the loading rod, and the sleeve.

[0015] Preferably, the bullet wave impedance is less than or equal to the loading rod wave impedance, i.e., (ρCA). 子弹 ≤(ρCA) 加载杆 In the formula, ρ is density, C is elastic wave velocity, and A is cross-sectional area.

[0016] Preferably, the cannon barrel has two pairs of through holes near its exit, the distance between the two pairs of through holes is less than 1 / 2 of the bullet length, and an photoelectric velocity sensor is installed on the through holes.

[0017] Preferably, the length of the induction coil is less than 1 / 2 of the bullet length; the distance between the midpoint of the induction coil along its length and the exit of the cannon barrel is 0.5 to 1 times the bullet length.

[0018] This invention also provides a dynamic hardness testing method, using the dynamic hardness testing system described above, comprising the following steps:

[0019] S1. Adjust the mounting bracket away from the hardness tester indenter and mount the sample on the mounting bracket;

[0020] S2. Adjust the mounting bracket to move the sample in front of the microscope objective lens, and adjust the distance between the sample and the objective lens until a clear image is obtained in the microscope;

[0021] S3. Adjust the mounting bracket to move the sample in front of the hardness tester indenter;

[0022] S4. Adjust the loading lever and limit it to the loading position;

[0023] S5. Start the loading device and conduct the test.

[0024] The present invention achieves the following technical effects compared to the prior art:

[0025] (1) The present invention places the focal plane of the objective lens of the microscope and the top of the hardness tester indenter on the same plane. The sample is moved by the moving platform. The microscope can determine that the sample has reached the focal plane of the objective lens. At the same time, the moving platform can move the sample from the focal plane of the objective lens to the top of the hardness tester indenter, thereby ensuring that the sample is in contact with the top of the hardness tester indenter and ensuring the installation accuracy of the sample.

[0026] (2) After dynamic hardness loading, the present invention can use a moving platform to move the sample to the focal plane of the microscope objective lens, that is, it can be observed in situ without removing the sample, and can observe the target indentation under experimental testing, thereby improving experimental efficiency and the accuracy of results.

[0027] (3) The present invention places the objective lens and the hardness tester indenter at the same height. The moving platform does not need a degree of freedom in the height direction. It only needs to include a Y-axis slide rail parallel to the axis of the loading rod and an X-axis slide rail parallel to the plane. It can switch the position between the focal plane of the objective lens and the top of the hardness tester indenter. The operation is simple and convenient, and the accuracy is high.

[0028] (4) The loading device of the present invention adopts an electromagnetic loading system, which can control the loading force on the bullet by controlling parameters such as the number of coil turns and loading voltage. It can control the firing speed of the bullet according to the experimental requirements. Therefore, it can apply a suitable loading force to materials with low toughness, such as ceramics and glass, to avoid large-area cracking of the indentation on the sample surface and ensure the smooth progress of the measurement. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 for Figure 1 Enlarged structural diagram at point A in the middle;

[0032] Figure 3 for Figure 1 Enlarged structural diagram at point B;

[0033] Figure 4 This is a schematic diagram illustrating the working principle of the present invention;

[0034] Figure 5 This is a schematic diagram of the state of the sample of the present invention at the front end of the indenter of the hardness tester;

[0035] Figure 6 This is a schematic diagram of the sample of the present invention in the focal plane of the objective lens;

[0036] The components are as follows: 1. Base plate; 2. Support frame; 3. Gun barrel; 4. Induction coil; 5. Photoelectric velocity sensor; 6. Bullet; 7. Flange; 8. Sleeve; 9. Mass block; 10. Loading rod; 11. Microscope; 12. X-axis slide rail; 13. Y-axis slide rail; 14. Mounting frame; 15. Hardness tester indenter; 16. Sample; 17. Pyroelectric sensor; 18. Signal acquisition system; 19. Charging control module; 20. Capacitor bank; 21. Rotary switch; 22. Discharge switch. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The purpose of this invention is to provide a dynamic hardness testing system and method to solve the problems existing in the prior art. By aligning the focal plane of the microscope objective lens with the top of the hardness tester indenter on the same plane, and moving the sample via a moving platform, the microscope can be used to determine when the sample reaches the focal plane of the objective lens. At the same time, the moving platform can be used to move the sample from the focal plane of the objective lens to the top of the hardness tester indenter, thereby ensuring that the sample is in contact with the top of the hardness tester indenter and guaranteeing the installation accuracy of the sample.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] like Figures 1-6As shown, this invention provides a dynamic hardness testing system, including a support frame 2, a loading rod 10 slidably disposed on the support frame 2, a microscope 11 fixedly mounted on the support frame 2, a loading device located on the force-bearing end side of the loading rod 10, and a mounting bracket 14 located on the force-applying end side of the loading rod 10. The support frame 2 may include multiple support points, each supporting multiple parts of the loading rod 10, ensuring stable support of the loading rod 10 along its length. Furthermore, the support frame 2 can be fixedly mounted on the same base plate 1, thus defining the position of each support point. The microscope 11 can be fixedly mounted at a support point near the force-applying end of the loading rod 10 to ensure the relative positional relationship between the objective lens of the microscope 11 and the hardness tester indenter 15. The loading device is used to provide a loading force to the force-bearing end of the loading rod 10, and can employ methods such as pneumatically propelled bullets 6, electromagnetically propelled bullets 6, or impact by a oscillating hammer. Mounting bracket 14 is used to mount sample 16. A piezoelectric sensor 17 can also be installed between sample 16 and mounting bracket 14 to convert force changes during the experiment into electrical signals for measurement and recording. A threaded hole can be provided at the force-applying end of loading rod 10. The tail of hardness tester indenter 15 has a threaded section, which is installed in the threaded hole for connection. The middle part of hardness tester indenter 15 is a cylindrical structure with the same diameter as loading rod 10; the remaining structure is consistent with that of a quasi-static Vickers hardness tester indenter. Loading rod 10 is limited to the loading position by a limiting structure. The loading position refers to the position where loading rod 10 can receive the loading force from the loading device and transmit the force to sample 16. The limiting structure refers to the structure that can limit loading rod 10 to one side of support bracket 2, restricting further movement towards sample 16. This can be achieved by providing a flange 7, stepped shaft, or other structures on loading rod 10. It should be noted that the objective lens is a fixed-focus lens. In the loading position, the top of the hardness tester indenter 15 and the focal plane of the objective lens of the microscope 11 are located on the same plane. That is, by moving within this plane, the position can be switched between the focal plane of the objective lens and the top of the hardness tester indenter 15. In other words, the plane where the top of the hardness tester indenter 15 is located can be confirmed through the microscope 11. The mounting bracket 14 is set on the moving platform. The moving platform can move in three degrees of freedom. In this case, the objective lens of the microscope 11 and the hardness tester indenter 15 may not be at the same height. Alternatively, the moving platform can move in only two degrees of freedom, without adjusting the height. In this case, the objective lens of the microscope 11 and the hardness tester indenter 15 can be at the same height, and the center point of the measurement plane of the sample 16 is at the same horizontal height as the axis of the loading rod 10. The sample 16 on the mounting bracket 14 can be moved to the plane and the top of the hardness tester indenter 15 via the moving platform.This invention aligns the focal plane of the objective lens of the microscope 11 with the top of the hardness tester indenter 15 on the same plane. By moving the sample 16 using a moving platform, the microscope 11 can ensure that the sample 16 reaches the focal plane of the objective lens. Simultaneously, the moving platform can move the sample 16 from the focal plane of the objective lens to the top of the hardness tester indenter 15, thus ensuring that the sample 16 is in contact with the top of the hardness tester indenter 15 and guaranteeing the installation accuracy of the sample 16. Furthermore, after completing the dynamic hardness loading, the moving platform can be used to move the sample 16 back to the focal plane of the objective lens of the microscope 11, allowing for in-situ observation without removing the sample 16. This enables observation of the target indentation under experimental testing, improving experimental efficiency and the accuracy of results.

[0041] The piezoelectric sensor 17 is connected to the signal acquisition system 18. Specifically, the signal acquisition system 18 may include a charge amplifier, a dynamic acquisition card, and a computer. The input terminal of the charge amplifier is connected to the piezoelectric sensor 17. The test signal is generated by the piezoelectric sensor 17, amplified by the charge amplifier, acquired and processed by the dynamic acquisition card, and then displayed on the computer as a curve waveform.

[0042] The objective lens of microscope 11 and the hardness tester indenter 15 can be located at the same height. In this case, the degree of freedom in the height direction is not required. That is, the moving platform only needs to include a Y-axis slide rail 13 parallel to the axis of the loading rod 10 and an X-axis slide rail 12 parallel to the plane (the same plane where the focal plane of the objective lens of microscope 11 and the top of the hardness tester indenter 15 are located). For details, please refer to... Figure 1 and Figure 5 , Figure 6As shown, the Y-axis slide rail 13 is fixed to the base plate 1, the X-axis slide rail 12 is fixed to a slider that can slide on the Y-axis slide rail 13, and the mounting bracket 14 is fixed to a slider that can slide on the X-axis slide rail 12. Thus, under the action of the X-axis slide rail 12 and the Y-axis slide rail 13, the distance between the sample 16 and the objective lens focal plane, the distance between the sample 16 and the top of the hardness tester indenter 15, and the position between the objective lens focal plane and the top of the hardness tester indenter 15 can be adjusted. Furthermore, to further improve the ease of operation and the installation accuracy of the sample 16, two working positions can be set on the X-axis slide rail 12: a first working position where the sample 16 faces the objective lens of the microscope 11, and a second working position where the sample 16 faces the hardness tester indenter 15. The first and second working positions can be located at opposite ends of the X-axis slide rail 12. After the mounting bracket 14 slides to the end, it can be positioned, thereby placing the sample 16 in either the first or second working position. The Y-axis slide rail 13 has a motion adjustment accuracy of less than 0.1 mm and a stroke greater than 20 mm. For example, the motion adjustment accuracy is 0.01 mm and the stroke is 50 mm to accommodate samples 16 of different thicknesses. It also features a locking structure to lock the slider moving on the Y-axis slide rail 13. The X-axis slide rail 12 does not require motion adjustment accuracy and can move rapidly in the direction perpendicular to the loading rod 10. When the mounting bracket 14 moves to the extreme position at one end of the X-axis slide rail 12 (second working position), the center of the test plane of the piezoelectric sensor 17 is on the axis of the loading rod 10. When the mounting bracket 14 moves to the extreme position at the other end of the X-axis slide rail 12 (first working position), the center of the test plane of the piezoelectric sensor 17 is on the axis of the microscope lens 11. Similarly, the X-axis slide rail 12 can also support position locking.

[0043] like Figure 1 and Figure 4 As shown, the limiting structure may include a mass block 9 mounted on the support frame 2 and a sleeve 8 fitted onto the loading rod 10. The mass block 9 has a through hole through which the loading rod 10 passes, and the two are clearance-fitted. A flange 7 is provided at the force-bearing end of the loading rod 10. The outer diameter of the flange 7 is larger than the inner diameter of the sleeve 8, and the outer diameter of the sleeve 8 is larger than the inner diameter of the through hole on the mass block 9. The length of the sleeve 8 is equal to the length of the bullet 6, its inner diameter is slightly larger than the diameter of the loading rod 10, and its cross-sectional area is the same as that of the loading rod 10. The area of ​​the flange 7 is equal to twice the cross-sectional area of ​​the loading rod 10, and its thickness is much smaller than the length of the bullet 6. In the loading position, one end of the sleeve 8 is attached to the flange 7, and the other end is attached to the mass block 9, thereby limiting the loading rod 10.

[0044] Combination Figure 4As shown, the loading device can employ an electromagnetic loading system, which includes a barrel 3 and an induction coil 4 fitted onto the barrel 3. The barrel 3 contains a slide for the bullet 6, allowing it to slide freely. The outlet of the barrel 3 faces the force-bearing end of the loading rod 10, i.e., the flange 7. The barrel 3 can be made of 304 stainless steel, with specific dimensions including a length of 200mm and an inner diameter of 5mm. The inner wall is polished to reduce frictional resistance. During firing, the impact end of the bullet 6 is positioned at the midpoint of the length of the induction coil 4 to ensure the efficiency of the induction coil 4 and the stability of the bullet 6's velocity. This invention's loading device uses an electromagnetic loading system, which can control the loading force on the bullet 6 by controlling parameters such as the number of coil turns and the loading voltage. It can also control the firing speed of the bullet 6 according to experimental requirements. Therefore, for materials with low toughness, such as ceramics and glass, it can apply an appropriate loading force, avoiding large-area cracking of the indentation on the sample 16 surface and ensuring smooth measurement.

[0045] Furthermore, the induction coil 4 may include a common terminal and several terminals, and a rotary switch 21. The rotary switch 21 has several positions, each connected to a terminal. The common terminal of the rotary switch 21 is connected to the common terminal of the induction coil 4. A capacitor bank 20 is connected in series between the common terminal of the rotary switch 21 and the common terminal of the induction coil 4, and a charging control module 19 is connected in parallel between the capacitor bank 20 and the common terminal. By adjusting the rotary switch 21 at different positions, the number of turns of the coil in the circuit connected to the induction coil 4 can be adjusted, thereby controlling the magnitude of the electromagnetic force and thus adjusting the firing speed of the bullet 6. Additionally, a discharge switch 22 can be provided between the capacitor bank 20 and the common terminal of the induction coil 4 to control the firing timing of the bullet 6. In one specific embodiment, the electromagnetic induction coil 4 is wound with enameled wire. The first end of the winding is the common terminal. After winding 50 turns, a terminal is led out. Another 50 turns are wound, and another terminal is led out, repeating this process until the terminal is led out, for a total of three sets. All the leads are connected to a three-position rotary switch 21. The leads from the common terminal of the rotary switch 21 are connected to the common terminal of the induction coil 4 via a discharge switch 22, and then to the two terminals of the capacitor bank 20. During operation, the number of turns of the induction coil 4 in the circuit can be controlled by adjusting the position knob of the rotary switch 21, thereby controlling the upper limit of the firing speed. The input terminal of the charging control module 19 is connected to a power supply, and the output terminal is connected to the capacitor bank 20. The charging voltage of the capacitor bank 20 is controlled by adjusting the potentiometer resistance in the charging control module 19, which is used to finely adjust the firing speed of the bullet 6. The length of the induction coil 4 can be 30mm; the distance between the midpoint of the coil length direction and the muzzle is 50mm to reduce the free sliding distance of the bullet 6 and reduce the influence of frictional resistance. The capacitor bank 20 can have a capacitance of 1F and a withstand voltage of 500V. The charging control module 19 has an adjustable charging voltage of 100-500V.

[0046] Flange 7, loading rod 10, sleeve 8, and mass block 9 are all made of the same material and are not magnetizable; for example, they are all made of 304 stainless steel. The length of loading rod 10 is greater than twice the length of bullet 6. The mass of mass block 9 is greater than twice the sum of the masses of flange 7, loading rod 10, and sleeve 8. The thickness of flange 7 can be 3mm; the diameter of loading rod 10 is 5mm and the length is 500mm; the outer diameter of mass block 9 is 50mm and the length is 50mm. Bullet 6 is made of ferromagnetic material and is driven by the magnetic field generated by induction coil 4. The length of bullet 6 can be 50-200mm, and the diameter is designed according to the diameter of loading rod 10. For example, bullet 6 is made of 45# steel, with a diameter of 4.95mm and a length of 100mm, satisfying the impedance matching relationship with loading rod 10.

[0047] Specifically, the impedance of the bullet wave 6 is less than or equal to the impedance of the loading rod wave 10, i.e., (ρCA). 子弹 ≤(ρCA) 加载杆 In the formula, ρ is density, C is elastic wave velocity, and A is cross-sectional area.

[0048] like Figure 2 As shown, the cannon barrel 3 has two pairs of through holes near its exit. The distance between the two pairs of through holes is less than half the length of the bullet 6. A photoelectric velocity sensor 5 is installed on each through hole to detect the velocity of the bullet 6 upon firing. In one specific embodiment, two pairs of through holes are provided at 30mm intervals, 10mm from the exit of the cannon barrel 3. The photoelectric velocity sensor 5 is installed on the through holes, forming a light path between each pair of through holes for measuring the velocity of the bullet 6.

[0049] The length of the induction coil 4 can be less than half the length of the bullet 6 to ensure that the force direction of the bullet 6 is consistent with the direction of motion throughout its entire journey. The distance between the midpoint of the length of the induction coil 4 and the exit of the barrel 3 is 0.5 to 1 times the length of the bullet 6 to reduce the free sliding distance of the bullet 6 and reduce the influence of frictional resistance.

[0050] Combined again Figures 1-6 As shown, the present invention also provides a dynamic hardness testing method, which can apply the dynamic hardness testing system described above, and includes the following steps:

[0051] S1. Adjust the mounting bracket 14 away from the hardness tester indenter 15. This adjustment can be achieved by adjusting its position on the Y-axis slide rail 13. Mount the sample 16 on the mounting bracket 14, and a piezoelectric sensor 17 can be placed between the sample 16 and the mounting bracket 14. The sample 16 is fixed to the test plane of the piezoelectric sensor 17 using grease or glue (e.g., ...). Figure 3 (As shown).

[0052] S2. Adjust the mounting bracket 14 to move the sample 16 in front of the objective lens of the microscope 11. During adjustment, based on the objective lens of the microscope 11 and the hardness tester indenter 15 being at the same height, this can be achieved by adjusting the position on the X-axis slide rail 12, for example, adjusting it to the extreme position on the front side of the microscope 11 (first working position, such as...). Figure 6 (As shown) and lock; adjust the distance between the sample 16 and the objective lens. At this time, the position on the Y-axis slide rail 13 can be adjusted until a clear image is obtained in the microscope 11, and the position of the Y-axis slide rail 13 is locked.

[0053] S3. Unlock the X-axis slide rail 12 and adjust the mounting bracket 14. This can be achieved by adjusting its position on the X-axis slide rail 12, for example, moving it to the extreme position (second working position) on the front side of the hardness tester indenter 15. Figure 5 (As shown) and lock; at this time, the sample 16 is located in front of the hardness tester indenter 15.

[0054] S4. Adjust the position of the loading rod 10 and limit it to the loading position using the limiting structure. Specifically, the sleeve 8 can be made to make close contact with the flanges 7 and the mass blocks 9 at both ends. After adjustment, the top of the hardness tester indenter 15 is just in contact with the surface of the sample 16.

[0055] S5. Start the loading device and conduct a test. When using an electromagnetic loading system, adjust the position of bullet 6 inside the barrel 3 so that the impact end of bullet 6 is located at the midpoint of the length of induction coil 4; rotate rotary switch 21 to the appropriate loading position; adjust the charging voltage of capacitor bank 20 through the potentiometer in charging control module 19 and charge capacitor bank 20. Open the data acquisition software of signal acquisition system 18 to prepare for data acquisition. Close discharge switch 22 and fire bullet 6 to complete the loading; save the raw data and process it to obtain the loading force-time curve.

[0056] After the recording is completed, step S6 can be performed, which is to unlock the X-axis slide rail 12, move the mounting bracket 14 to the extreme position (first working position) close to the front side of the microscope 11 and lock it, observe and measure the diagonal distance of the indentation in the microscope 11, and calculate the dynamic hardness test value in combination with the peak loading force.

[0057] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A dynamic hardness testing system, characterized in that: It includes a support frame (2), a loading rod (10) slidably disposed on the support frame (2), a microscope (11) fixedly mounted on the support frame (2), a loading device located on the force-bearing end side of the loading rod (10), and a mounting frame (14) located on the force-applying end side of the loading rod (10). A hardness tester indenter (15) is installed at the force application end. The loading rod (10) is limited to the loading position by a limiting structure. At the loading position, the top of the hardness tester indenter (15) and the focal plane of the objective lens of the microscope (11) are on the same plane. The mounting bracket (14) is set on the moving platform. The moving platform includes a Y-axis slide rail (13) parallel to the axis of the loading rod and an X-axis slide rail (12) parallel to the plane. The focal plane of the objective lens of the microscope (11) and the top of the hardness tester indenter (15) are on the same plane. The sample is moved by the moving platform. The microscope (11) can determine that the sample has reached the focal plane of the objective lens. At the same time, the moving platform can move the sample from the focal plane of the objective lens to the top of the hardness tester indenter (15). Thus, it can be determined that the sample is just in contact with the top of the hardness tester indenter (15) to ensure the installation accuracy of the sample. The loading device adopts an electromagnetic loading system, which includes a gun barrel (3) and an induction coil (4) sleeved on the gun barrel (3). The gun barrel (3) is used to place the bullet (6), and the outlet of the gun barrel (3) is directly facing the force-bearing end. The induction coil (4) includes a common terminal and several terminals. The rotary switch (21) includes several positions. Each position of the rotary switch (21) is connected to a terminal. The common terminal of the rotary switch (21) is connected to the common terminal of the induction coil (4). A capacitor bank (20) is connected in series between the common terminal of the rotary switch (21) and the common terminal of the induction coil (4). A charging control module (19) is connected in parallel to the capacitor bank (20). By adjusting the rotary switch (21) at different positions, the number of coil turns in the circuit connected to the induction coil (4) can be adjusted, thereby controlling the magnitude of the electromagnetic force and thus adjusting the firing speed of the bullet (6). Two pairs of through holes are provided near the exit of the cannon barrel (3). The distance between the two pairs of through holes is less than 1 / 2 of the length of the bullet (6). Photoelectric velocity sensors (5) are installed on the through holes.

2. The dynamic hardness testing system according to claim 1, characterized in that: The limiting structure includes a mass block (9) mounted on the support frame (2) and a sleeve (8) sleeved on the loading rod (10). The force-bearing end is provided with a flange (7). In the loading position, one end of the sleeve (8) is attached to the flange and the other end is attached to the mass block (9).

3. The dynamic hardness testing system according to claim 2, characterized in that: The flange (7), loading rod (10), sleeve (8), and mass block (9) are all made of the same material and cannot be magnetized; the length of the loading rod (10) is more than twice the length of the bullet (6); the mass of the mass block (9) is more than twice the sum of the masses of the flange (7), loading rod (10), and sleeve (8).

4. The dynamic hardness testing system according to claim 3, characterized in that: The wave impedance of the bullet (6) is less than or equal to the wave impedance of the loading rod (10), that is... In the formula, ρ is density, C is elastic wave velocity, and A is cross-sectional area.

5. The dynamic hardness testing system according to claim 4, characterized in that: The length of the induction coil (4) is less than 1 / 2 of the length of the bullet (6); the distance between the midpoint of the length of the induction coil (4) and the exit of the cannon barrel (3) is 0.5 to 1 times the length of the bullet (6).

6. A dynamic hardness testing method, characterized in that, The application of the dynamic hardness testing system as described in any one of claims 1-5 includes the following steps: S1. Adjust the mounting bracket (14) away from the hardness tester indenter (15) and mount the sample on the mounting bracket (14); S2. Adjust the mounting bracket (14), move the sample to the front of the objective lens of the microscope (11), and adjust the distance between the sample and the objective lens until a clear image is obtained in the microscope (11). S3. Adjust the mounting bracket (14) to move the sample in front of the hardness tester indenter (15); S4. Adjust the loading lever (10) and limit it to the loading position; S5. Start the loading device and conduct the test.

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