CN115639090A - Dynamic hardness testing system and dynamic hardness testing method thereof - Google Patents

Abstract

The invention discloses a dynamic hardness testing system and a dynamic hardness testing method thereof, belonging to the field of material dynamic mechanics experiments and comprising a support frame, a loading rod arranged on the support frame in a sliding manner, a microscope fixedly arranged on the support frame, a loading device positioned on the stressed end side of the loading rod and an installation frame positioned on the force application end side of the loading rod, wherein a hardness tester pressure head is arranged on the force application end, the loading rod is limited at a loading position through a limiting structure, the top end of the hardness tester pressure head and the objective lens focal plane of the microscope are positioned on the same plane at the loading position, the installation frame is arranged on a mobile platform, and a sample on the installation frame can be moved to the plane and the top end of the hardness tester pressure head through the mobile platform. According to the invention, by moving the sample, the fact that the sample reaches the focal plane of the objective lens can be determined by using the microscope, and meanwhile, the sample can be moved to the top end of the indenter of the hardness tester from the focal plane of the objective lens, so that the fact that the sample just contacts with the top end of the indenter of the hardness tester can be determined, and the mounting precision of the sample is ensured.

Description

Dynamic hardness testing system and dynamic hardness testing method thereof

Technical Field

The invention relates to the field of material dynamic mechanics experiments, in particular to a dynamic hardness testing system and a dynamic hardness testing method thereof.

Background

Hardness is often used to characterize a material's ability to resist indentation deformation, reflecting the material's yield strength, strain hardening ability, or strength of the interatomic bond, among others. Traditional hardness tests can characterize the mechanical properties of materials under quasi-static conditions, but the strain rate effect of the materials is proved that the hardness index under quasi-static conditions is inaccurate for describing the mechanical properties of the materials under dynamic loading conditions.

Based on the traditional Hopkinson device, the dynamic hardness test system established according to the single pulse loading principle can realize the dynamic hardness test of the material under the condition of medium and high strain rate. However, in the actual test process, the problem of the mounting accuracy of the test sample exists in the conventional dynamic hardness testing device, specifically, before the dynamic hardness test, the test sample is just contacted with a pressure head of a hardness tester, the distance between the test sample and the pressure head is too large, the pressure head cannot reach the test sample in the loading process, or the loading force is smaller than a set range, and the repeatability of the test result is poor; if the sample surface is too close to the indenter to ensure the success rate of loading, pre-loading may result, or a gap may occur between the loading rod flange and the sleeve resulting in secondary loading.

The prior patent literature discloses a dynamic test scheme of indentation or hardness, for example, chinese patent with application publication No. CN 108072579A discloses a variable-speed impact indentation test device and method, which comprises a servo motor driving unit, a belt pulley transmission unit, a worm and gear transmission unit, an electromagnetic clutch control unit, a pendulum bob movement unit, an impact rod support detection unit and an observation unit, wherein the servo motor driving unit and the belt pulley transmission unit are connected to a small belt pulley, the belt pulley transmission unit is connected with the worm and gear transmission unit, and a worm wheel of the worm and gear transmission unit is placed on a transmission main shaft II; the pendulum sleeve is connected with the main shaft I, and the pendulum motion unit impacts the impact rod of the impact rod supporting detection unit to complete motion. The scheme discloses a loading mode of impacting an impact rod by using a pendulum bob, a test piece is placed at a test piece supporting seat through a test piece clamping nail, however, how to determine the relative position of the impact rod and the test piece is not described, and the problem of the installation accuracy of the test piece and the impact rod still exists.

For another example, chinese patent application publication No. CN 115046874a discloses a method for testing dynamic hardness of a coating, the adopted dynamic hardness testing apparatus includes a pneumatic control mechanism, a bullet, a waveform shaper, an incident rod, a resistance strain gauge, a pressure head, a sample, a piezoelectric force sensor, a bracket and a computer, the sample is placed on the piezoelectric force sensor during testing, and lightly contacts with the pressure head, the pressure head at the end of the incident rod is driven by impacting the incident rod to load the surface of the sample with different loading forces by controlling different loading speeds of the bullet, and the loading force is recorded by the computer. The scheme only describes a test method in a general way, and the description that the sample is in light contact with the pressure head cannot accurately judge whether the sample is in right contact at a microscopic level if judged by naked eyes, namely how to ensure the sample installation precision of the scheme is not disclosed.

Therefore, how to ensure the mounting accuracy of the sample is a technical problem to be solved urgently in the dynamic hardness test.

Disclosure of Invention

The objective focal plane of the microscope and the top end of the indenter of the hardness tester are positioned on the same plane, the sample is moved by the moving platform, the sample can be confirmed to reach the objective focal plane by the microscope, and meanwhile, the sample can be moved to the top end of the indenter of the hardness tester from the objective focal plane by the moving platform, so that the sample can be confirmed to be just in contact with the top end of the indenter of the hardness tester, and the mounting precision of the sample is guaranteed.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a dynamic hardness testing system which comprises a supporting frame, a loading rod, a microscope, a loading device and a mounting frame, wherein the loading rod is arranged on the supporting frame in a sliding mode, the microscope is fixedly arranged on the supporting frame, the loading device is positioned on the force application end side of the loading rod, the mounting frame is positioned on the force application end side of the loading rod, a hardness tester pressure head is arranged on the force application end, the loading rod is limited at a loading position through a limiting structure, the top end of the hardness tester pressure head and the objective lens focal plane of the microscope are positioned on the same plane at the loading position, the mounting frame is arranged on a movable platform, and a test sample on the mounting frame can be moved to the plane and the top end of the hardness tester pressure head through the movable platform.

Preferably, the objective lens and the indenter are located at the same height, and the moving platform includes a Y-axis slide parallel to the axial direction of the loading rod and an X-axis slide parallel to the plane.

Preferably, limit structure is including installing quality piece and the cover on the support frame are established sleeve on the loading pole, the stress end is provided with the flange the loading position, telescopic one end laminating is in on the flange, the other end laminating is in on the quality piece.

Preferably, the loading device adopts an electromagnetic loading system, the electromagnetic loading system comprises a gun barrel and an induction coil sleeved on the gun barrel, bullets are placed in the gun barrel, and an outlet of the gun barrel is opposite to the stress end.

Preferably, the induction coil includes a common terminal and a plurality of terminals, each gear of the rotary switch is connected to the terminal, 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 the capacitor bank is connected in parallel with the charging control module.

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 more than 2 times of the length of the bullet; the mass of the mass block is 2 times greater than the sum of the mass of the flange, the loading rod and the sleeve.

Preferably, the bullet wave impedance is equal to or less than the load beam wave impedance, i.e. (ρ CA) _Bullet ≤(ρCA) _{Loading rod} Where ρ is the density, C is the elastic wave velocity, and A is the cross-sectional area.

Preferably, two pairs of through holes are formed in the position, close to the outlet of the gun barrel, the distance between the two pairs of through holes is smaller than 1/2 of the length of the bullet, and a photoelectric speed measurement sensor is mounted on each through hole.

Preferably, the length of the induction coil is less than 1/2 of the bullet length; the distance between the midpoint position of the induction coil in the length direction and the outlet of the gun barrel is 0.5-1 time of the length of the bullet.

The invention also provides a dynamic hardness testing method, which applies the dynamic hardness testing system recorded in the foregoing and comprises the following steps:

s1, adjusting an installation frame to be far away from a indenter head of a hardness tester, and installing a test sample on the installation frame;

s2, adjusting the mounting rack, moving the sample to the front of an objective lens of a microscope, and adjusting the distance between the sample and the objective lens until a clear image is obtained in the microscope;

s3, adjusting the mounting rack, and moving the test sample to the front of the indenter of the hardness tester;

s4, adjusting a loading rod and limiting the loading rod at a loading position;

and S5, starting a loading device for testing.

Compared with the prior art, the invention achieves the following technical effects:

(1) According to the invention, the objective focal plane of the microscope and the top end of the indenter of the hardness tester are positioned on the same plane, the sample is moved by the moving platform, the microscope can be used for determining that the sample reaches the objective focal plane, and meanwhile, the moving platform can be used for moving the sample from the objective focal plane to the top end of the indenter of the hardness tester, so that the sample can be determined to be just in contact with the top end of the indenter of the hardness tester, and the mounting precision of the sample is ensured;

(2) After the dynamic hardness loading, the sample can be moved to the objective focal plane of the microscope by using the moving platform, namely, the sample can be observed in situ without being taken down, a target indentation under an experimental test can be observed, and the experimental efficiency and the accuracy of a result are improved;

(3) According to the invention, the objective lens and the indenter of the hardness tester are positioned at the same height, the mobile platform does not need the freedom degree in the height direction, and only needs to comprise the Y-axis slide rail parallel to the axial direction of the loading rod and the X-axis slide rail parallel to the plane, so that the position switching between the focal plane of the objective lens and the top end of the indenter of the hardness tester can be realized, the operation is simple and convenient, and the accuracy is high;

(4) The loading device adopts an electromagnetic loading system, can control the loading force on the bullet by controlling parameters such as the number of turns of the coil, loading voltage and the like, and can control the launching speed of the bullet according to experimental requirements, so that the loading device can apply the appropriate loading force on materials with low toughness such as ceramics, glass and the like, avoid the phenomenon of large-area bursting of indentation on the surface of a sample, and ensure the smooth measurement.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is an enlarged schematic view of the structure at A in FIG. 1;

FIG. 3 is an enlarged view of the structure at B in FIG. 1;

FIG. 4 is a schematic diagram of the working principle of the present invention;

FIG. 5 is a schematic view of a sample of the present invention in the forward position of the indenter of the durometer;

FIG. 6 is a schematic diagram of the sample in the focal plane of the objective lens according to the present invention;

wherein, 1, a bottom plate; 2. a support frame; 3. a gun barrel; 4. an induction coil; 5. a photoelectric speed measuring sensor; 6. a bullet; 7. a flange; 8. a sleeve; 9. a mass block; 10. a loading rod; 11. a microscope; 12. an X-axis slide rail; 13. a Y-axis slide rail; 14. a mounting frame; 15. a durometer indenter; 16. a sample; 17. a piezoelectric force sensor; 18. a signal acquisition system; 19. a charging control module; 20. a capacitor bank; 21. a rotary switch; 22. and (4) discharging a switch.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The objective focal plane of the microscope and the top end of a hardness tester pressure head are positioned on the same plane, a sample is moved through the moving platform, the sample can be confirmed to reach the objective focal plane through the microscope, and meanwhile, the sample can be moved to the top end of the hardness tester pressure head from the objective focal plane through the moving platform, so that the sample can be confirmed to be just in contact with the top end of the hardness tester pressure head, and the mounting precision of the sample is guaranteed.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1 to 6, the present invention provides a dynamic hardness testing system, which includes a supporting frame 2, a loading rod 10 slidably disposed on the supporting frame 2, a microscope 11 fixedly mounted on the supporting frame 2, a loading device located on a force-receiving end side of the loading rod 10, and a mounting frame 14 located on a force-applying end side of the loading rod 10. Wherein, support frame 2 can support a plurality of positions of loading arm 10 respectively including a plurality of strong points, guarantees that loading arm 10 supports at length direction stable support to, support frame 2 can fixed mounting on same bottom plate 1, realizes prescribing a limit to the position of each strong point. The microscope 11 may be fixedly mounted at a support point near the force application end of the load lever 10 to enable a relative positional relationship of the objective lens of the microscope 11 and the indenter 15 to be secured. The loading device is used for providing loading force to the force bearing end of the loading rod 10, and can adopt a mode of pneumatically pushing the bullet 6, a mode of electromagnetically pushing the bullet 6, a mode of swinging hammer impact and the like. The mounting frame 14 is used for mounting the sample 16, and a piezoelectric sensor 17 can be arranged between the sample 16 and the mounting frame 14, so that the change of force in the experimental process can be converted into an electric signal to be measured and recorded. The application of force end at loading arm 10 can be provided with the screw hole, and sclerometer pressure head 15 afterbody is equipped with the screw thread section, installs the screw thread section of sclerometer pressure head 15 in this screw hole and connects, and the mid portion of sclerometer pressure head 15 is the cylinder structure, and the diameter is the same with loading arm 10, and all the other structures are unanimous with quasi-static vickers hardness pressure head. The load bar 10 is retained in the load position by a retaining structure, which means that the load bar 10 is able to receive the loading force of the loading device and transfer the force to the test sample 16 in this position. The limit structure means that the loading rod 10 can be limited at one side of the support frame 2, and the limit can be continuously moved towards the direction of the sample 16, and the limit can be realized by arranging a flange 7, a stepped shaft and other structures on the loading rod 10. The objective lens is a fixed focus lens, and in the loading position, the tip of the indenter 15 and the objective lens focal plane of the microscope 11 are located on the same plane, that is, by moving in the plane, the position can be switched between the objective lens focal plane and the tip of the indenter 15, that is, the plane on which the tip of the indenter 15 is located can be confirmed by the microscope 11. The mounting frame 14 is disposed on a moving platform, and the moving platform can move in three degrees of freedom, at this time, the objective lens of the microscope 11 and the indenter 15 of the hardness tester may not be at the same height; the movable platform may have only two-degree-of-freedom movement, and does not include height adjustment, in which case the objective lens of the microscope 11 and the indenter 15 may be at the same height, and the center point of the measurement plane of the sample 16 and the axis of the loading rod 10 are at the same level. The sample 16 on the mounting rack 14 can be moved to the flat surface and top of the indenter 15 by the motion stage. According to the invention, the objective focal plane of the microscope 11 and the top end of the indenter 15 of the hardness tester are positioned on the same plane, the sample 16 is moved by the moving platform, the microscope 11 can be used for determining that the sample 16 reaches the objective focal plane, and meanwhile, the moving platform can be used for moving the sample 16 from the objective focal plane to the top end of the indenter 15 of the hardness tester, so that the sample 16 can be determined to be just in contact with the top end of the indenter 15 of the hardness tester, and the installation accuracy of the sample 16 is ensured; meanwhile, after the dynamic hardness loading is completed, the sample 16 can be moved to the objective focal plane of the microscope 11 by using the moving platform, namely, the sample 16 can be observed in situ without being taken down, a target indentation under an experimental test can be observed, and the experimental efficiency and the accuracy of a result are improved.

The piezoelectric force 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, an input end of the charge amplifier is connected to the piezoelectric force sensor 17, a test signal is generated by the piezoelectric force sensor 17, amplified by the charge amplifier and then acquired and processed by the dynamic acquisition card, and a curve waveform is displayed on the computer.

The objective of the microscope 11 and the indenter 15 may be at the same height, and at this time, it may not be necessary to include the degree of freedom in the height direction, i.e., the moving platform only needs to include the Y-axis slide rail 13 parallel to the axial direction of the loading rod 10 and the X-axis slide rail 12 parallel to the plane (the same plane as the focal plane of the objective of the microscope 11 and the top end of the indenter 15). Specifically, as shown in fig. 1, 5 and 6, 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, so that the distance between the sample 16 and the focal plane of the objective lens, the distance between the sample 16 and the top end of the durometer indenter 15, and the position between the focal plane of the objective lens and the top end of the durometer indenter 15 can be adjusted by the X-axis slide rail 12 and the Y-axis slide rail 13. In addition, in order to further improve the convenience of operation and the installation accuracy of the sample 16, two working positions can be arranged on the X-axis slide rail 12, namely, the sample 16 is just opposite to a first working position of an objective lens of the microscope 11 and the sample 16 is just opposite to a second working position of the hardness tester indenter 15, the first working position and the second working position can be respectively positioned at two end parts of the X-axis slide rail 12, the mounting frame 14 can be positioned after sliding to the end parts, and then the sample 16 is positioned at the first working position or the second working position. The motion adjustment precision of the Y-axis slide rail 13 is less than 0.1mm, the motion stroke is more than 20mm, for example, the motion adjustment precision is 0.01mm, the motion stroke is 50mm, so as to correspond to the test samples 16 with different thicknesses, and a locking structure is arranged, so that a slide block moving on the Y-axis slide rail 13 can be locked. The X-axis slide rail 12 can be moved fast in the direction perpendicular to the loading rod 10 without considering the precision of motion adjustment, when the mounting bracket 14 is moved to the extreme position (second working position) at one end of the X-axis slide rail 12, the center of the test plane of the piezoelectric force sensor 17 is located on the axis of the loading rod 10, and when the mounting bracket 14 is moved to the extreme position (first working position) at the other end of the X-axis slide rail 12, the center of the test plane of the piezoelectric force sensor 17 is located on the axis of the lens of the microscope 11. Likewise, the X-axis slide rail 12 may also support position locking.

As shown in fig. 1 and 4, the limiting structure may include a mass block 9 mounted on the supporting frame 2 and a sleeve 8 sleeved on the loading rod 10, the mass block 9 is provided with a through hole capable of penetrating through the loading rod 10, and the loading rod 10 passes through the through hole, and the two are in clearance fit. The loading rod 10 is provided with a flange 7 at the stress end, 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 arranged on the mass block 9. The length of the sleeve 8 is equal to the length of the bullet 6, the inner diameter is slightly larger than the diameter of the loading rod 10, and the 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 the 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, so that the loading rod 10 is limited.

Referring to fig. 4, the loading device may adopt an electromagnetic loading system, the electromagnetic loading system includes a barrel 3 and an induction coil 4 sleeved on the barrel 3, the barrel 3 is used for placing the bullet 6 and forming a slideway for the free sliding of the bullet 6, and an outlet of the barrel 3 is opposite to a stressed end, i.e. the flange 7, of the loading rod 10. The gun barrel 3 can be made of 304 stainless steel, and the specific setting sizes can be as follows: the length is 200mm, the inner diameter is 5mm, and the inner wall is polished to reduce frictional resistance. When the bullet is launched, the impact end of the bullet 6 is adjusted to be positioned at the midpoint of the induction coil 4 in the length direction, so that the work efficiency of the induction coil 4 and the stability of the speed of the bullet 6 are ensured. The loading device adopts an electromagnetic loading system, can control the loading force on the bullet 6 by controlling parameters such as the number of turns of a coil, loading voltage and the like, and can control the launching speed of the bullet 6 according to experimental requirements, so that the loading device can apply a proper loading force on materials with low toughness such as ceramics, glass and the like, avoid the phenomenon of large-area bursting of indentation on the surface of the sample 16, and ensure the smooth measurement.

Further, the induction coil 4 may include a common terminal and a plurality of terminals, and further includes a rotary switch 21, the rotary switch 21 includes a plurality of gears, each gear is connected to a terminal, meanwhile, the common terminal of the rotary switch 21 is connected to the common terminal of the induction coil 4, and a capacitor bank 20 is further connected in series between the common terminal of the rotary switch 21 and the common terminal of the induction coil 4, and the capacitor bank 20 is connected in parallel to the charging control module 19. The number of turns of the coil of the induction coil 4 connected into the circuit can be adjusted by adjusting the rotary switch 21 at different gears, so that the electromagnetic force can be controlled, and the firing speed of the bullet 6 can be adjusted. In addition, a discharge switch 22 may be provided between the capacitor bank 20 and the common terminal of the induction coil 4 for controlling the firing timing of the bullet 6. In a specific embodiment, the electromagnetic induction coil 4 is formed by winding an enameled wire, one end of the enameled wire which starts to be wound is a common end, a wiring terminal is led out after 50 turns of winding is performed, a wiring terminal is led out after 50 turns of winding is continued, and the steps are repeated until the leading-out of the wiring terminals is completed, wherein 3 groups of wiring terminals are counted. All the terminals are connected to a rotary switch 21 with 3 gears, are led out through the common end of the rotary switch 21, and are connected with the common end of the induction coil 4 through a discharge switch 22 to two stages of the capacitor bank 20, and the number of turns of the induction coil 4 connected into the circuit can be controlled by adjusting the gear knob of the rotary switch 21 during operation, so that the upper limit of the transmitting speed is controlled. The input end of the charging control module 19 is connected with a power supply, the output end of the charging control module 19 is connected with the capacitor bank 20, and the charging voltage of the capacitor bank 20 is controlled by adjusting the resistance value of a potentiometer in the charging control module 19 so as to finely adjust the shooting speed of the bullet 6. The length of the induction coil 4 may be 30mm; the distance between the middle point position of the coil in the length direction and the muzzle is 50mm, so that the free sliding distance of the bullet 6 is reduced, and the influence of frictional resistance is reduced. The capacitor bank 20 may have a capacity of 1F and a withstand voltage of 500v. The charging control module 19 can adjust the charging voltage to 100-500 v.

The flange 7, the loading rod 10, the sleeve 8 and the mass 9 are all made of the same material and are not magnetizable, for example, all made of 304 stainless steel. The length of the loading rod 10 is more than 2 times the length of the bullet 6. The mass of the mass 9 is 2 times greater than the sum of the masses of the flange 7, the loading rod 10 and the sleeve 8. The thickness of the flange 7 may be 3mm; the diameter of the loading rod 10 is 5mm, and the length is 500mm; the mass 9 has an outer diameter of 50mm and a length of 50mm. The bullet 6 is made of ferromagnetic material and driven by the magnetic field generated by the induction coil 4, the length of the bullet 6 can be 50-200 mm, and the diameter of the bullet 6 is designed according to the diameter of the loading rod 10, for example, the bullet 6 is made of 45# steel, the diameter is 4.95mm, the length is 100mm, and the bullet and the loading rod 10 meet the wave impedance matching relation.

Specifically, the bullet 6 wave impedance is equal to or less than the load beam 10 wave impedance, i.e. (ρ CA) _Bullet ≤(ρCA) _{Loading rod} Where ρ is the density, C is the elastic wave velocity, and A is the cross-sectional area.

As shown in fig. 2, two pairs of through holes are formed in the position of the gun barrel 3 close to the outlet, the distance between the two pairs of through holes is smaller than 1/2 of the length of the bullet 6, and the through holes are provided with photoelectric speed measuring sensors 5 which can detect the shooting speed of the bullet 6. In a particular embodiment, two pairs of through holes are provided spaced 30mm apart from the outlet of the barrel 3 by 10mm, and the photoelectric speed-measuring sensor 5 is mounted above the through holes, with a light path being formed between each pair of through holes for the speed measurement of the cartridges 6.

The length of the induction coil 4 can be less than 1/2 of the length of the bullet 6, so that the stress direction of the bullet 6 in the whole process can be consistent with the movement direction. The distance between the midpoint position of the induction coil 4 in the length direction and the outlet of the gun barrel 3 is 0.5-1 time of the length of the bullet 6, so that the free sliding distance of the bullet 6 can be reduced, and the influence of frictional resistance is reduced.

Referring to fig. 1 to 6 again, the present invention further provides a dynamic hardness testing method, which can be applied to the dynamic hardness testing system described above, and includes the following steps:

s1, adjusting the mounting frame 14 to be far away from the hardness tester indenter 15, wherein during adjustment, the position on the Y-axis slide rail 13 can be adjusted, the sample 16 is mounted on the mounting frame 14, and a piezoelectric force sensor 17 can be arranged between the sample 16 and the mounting frame 14, namely, the sample 16 is fixed on a test plane of the piezoelectric force sensor 17 by using lubricating grease or glue (as shown in FIG. 3).

S2, adjusting the mounting frame 14 to move the sample 16 to the front of the objective lens of the microscope 11, wherein during adjustment, on the basis that the objective lens of the microscope 11 and the indenter 15 are at the same height, the adjustment can be realized by adjusting the position on the X-axis slide rail 12, for example, the adjustment is carried out to the limit position (a first working position, shown in FIG. 6) at the front side of the microscope 11 and is locked; the distance between the specimen 16 and the objective lens is adjusted, at which time the position on the Y-axis slide 13 can be adjusted until a clear image is obtained in the microscope 11, locking the Y-axis slide 13 position.

S3, unlocking the X-axis slide rail 12 and adjusting the mounting frame 14 can be achieved by adjusting the position on the X-axis slide rail 12, for example, moving to the limit position (a second working position, shown in FIG. 5) on the front side of the hardness tester indenter 15 and locking; at this time, the sample 16 is positioned in front of the indenter 15.

S4, adjusting the position of the loading rod 10, and limiting the position at the loading position by using a limiting structure, wherein the sleeve 8 can be respectively in close contact with the flanges 7 and the mass blocks 9 at the two ends of the sleeve; by adjustment, the tip of the indenter 15 is now just in contact with the surface of the sample 16.

S5, starting a loading device for testing, and adjusting the position of the bullet 6 in the gun barrel 3 when an electromagnetic loading system is adopted, so that the impact end of the bullet 6 is positioned at the middle point of the induction coil 4 in the length direction; rotating the rotary switch 21 to a proper loading gear; the charging voltage of the capacitor bank 20 is regulated by a potentiometer in the charging control module 19 and the capacitor bank 20 is charged. The data acquisition software of signal acquisition system 18 is turned on in preparation for data acquisition. Closing the discharge switch 22, and firing the bullet 6 to complete loading; and storing the original data, and processing to obtain a loading force-time curve.

After the description is completed, step S6 of unlocking the X-axis slide rail 12, moving the mounting bracket 14 to an extreme position (first working position) near the front side of the microscope 11 and locking, observing and measuring the diagonal distance of the indentation in the microscope 11, and calculating the dynamic hardness test value in combination with the peak value of the loading force may be further performed.

The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.

Claims (10)

1. A dynamic hardness testing system, comprising: set up including support frame, slip loading pole, fixed mounting on the support frame are in microscope on the support frame, be located the distolateral loading device of atress of loading pole and being located the distolateral mounting bracket of application of force of loading pole, the sclerometer pressure head is installed to the end of exerting force, the loading pole is injectd in the loading position through limit structure the loading position, the top of sclerometer pressure head with microscope's objective focal plane is located the coplanar, the mounting bracket sets up on moving platform, sample on the mounting bracket passes through moving platform can move to the plane and the top of sclerometer pressure head.

2. The dynamic stiffness test system of claim 1, wherein: the objective lens and the hardness tester pressure head are located at the same height, and the moving platform comprises a Y-axis slide rail parallel to the axial direction of the loading rod and an X-axis slide rail parallel to the plane.

3. The dynamic stiffness testing system of claim 1 or 2, wherein: limiting structure establishes including installing quality piece and the cover on the support frame sleeve on the loading rod, the stress end is provided with the flange the loading position, telescopic one end laminating is in on the flange, the other end laminating is in on the quality piece.

4. The dynamic stiffness test system of claim 3, wherein: the loading device adopts an electromagnetic loading system, the electromagnetic loading system comprises a gun barrel and an induction coil sleeved on the gun barrel, bullets are placed in the gun barrel, and an outlet of the gun barrel is opposite to the stress end.

5. The dynamic stiffness test system of claim 4, wherein: the induction coil comprises a common end and a plurality of wiring ends, each gear of the rotary switch is connected with the wiring ends respectively, the common end of the rotary switch is connected with the common end of the induction coil, a capacitor bank is connected in series between the common end of the rotary switch and the common end of the induction coil, and the capacitor bank is connected with a charging control module in parallel.

6. The dynamic stiffness test system of claim 4, wherein: 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 2 times of the length of the bullet; the mass of the mass block is 2 times larger than the sum of the mass of the flange, the loading rod and the sleeve.

7. The dynamic stiffness testing system of claim 4The method is characterized in that: the bullet wave impedance is less than or equal to the load beam wave impedance, i.e. (ρ CA) _Bullet ≤(ρCA) _{Loading rod} Where ρ is the density, C is the elastic wave velocity, and A is the cross-sectional area.

8. The dynamic stiffness test system of claim 4, wherein: two pairs of through holes are formed in the position, close to the outlet, of the gun barrel, the distance between the two pairs of through holes is smaller than 1/2 of the length of the bullet, and a photoelectric speed measurement sensor is mounted on the through holes.

9. The dynamic stiffness test system of claim 4, wherein: the length of the induction coil is less than 1/2 of the length of the bullet; the distance between the midpoint position of the induction coil in the length direction and the outlet of the gun barrel is 0.5-1 time of the length of the bullet.

10. A dynamic hardness testing method using the dynamic hardness testing system according to any one of claims 1 to 9, comprising the steps of:

s1, adjusting an installation frame to be far away from a pressure head of a hardness tester, and installing a test sample on the installation frame;

s2, adjusting the mounting rack, moving the sample to the front of an objective lens of a microscope, and adjusting the distance between the sample and the objective lens until a clear image is obtained in the microscope;

s3, adjusting the mounting rack, and moving the test sample to the front of the indenter of the hardness tester;

s4, adjusting a loading rod and limiting the loading rod at a loading position;

and S5, starting a loading device for testing.

Images