A dynamic hardness testing device and testing method

Abstract

The present invention provides a dynamic hardness testing device and testing method, the structure of which includes a loading sleeve and a guide tube, a support seat is fixed at the bottom end of the guide tube, the top end of the guide tube is located at the inner layer of the bottom end of the loading sleeve and is slidably connected with the loading sleeve, the escapement rod penetrates the interior of the loading sleeve and the guide tube from top to bottom, the bottom of the escapement rod is clamped with an impact body, and a permanent magnet is arranged inside the impact body; a monitoring device is sleeved on the outer side of the bottom of the guide tube, and an induction coil is arranged in the monitoring device, and the induction coil is connected to an external test instrument through a wire. When the magnetic impact body passes through the induction coil, the present invention uses a high-speed acquisition circuit to capture and record the speed change at the moment of impact, and subtracts the point of rebounding from the maximum speed by 2% from the time point when the speed starts to drop by 2%, and obtains the impact time △T. By using the impact time as the hardness measurement method, the dynamic hardness can be conveniently measured, and compared with the static hardness, it can better reflect the recovery deformation speed of the material when it is impacted.

Description

Technical Field

[0001] The present invention relates to the technical field of hardness testing, and in particular to a dynamic hardness testing device and a testing method. Background Art

[0002] When the material is impacted, along with the start of the contact impact, the impacted object will give the impact head a resistance, causing the impact head speed to drop to zero, and then accelerate away from the object in the reverse direction. This impact time △T is directly related to the hardness of the material. The shorter the time, the greater the hardness.

[0003] Among the existing hardness test instruments, static hardness testers such as Brinell hardness, Vickers hardness, Rockwell hardness, Shore hardness, etc. all use an indenter to apply a force to an object to measure the size of the compression deformation or the size of the scratch. Impact hardness testers such as Shore hardness and Leeb hardness calculate the hardness based on the impact rebound height or the impact velocity ratio.

[0004] After fatigue aging, many materials, including rubber, have little change in static hardness, but the speed of impact recovery has changed greatly. The rubber hardness measured by the impact method of Leeb and Shore hardness testers has a completely different trend from the Shore hardness, and rebound cannot be used to characterize the hardness. Using impact time as a hardness measurement method, after testing a variety of materials, dynamic hardness can be easily measured. Compared with static hardness, it can better reflect the recovery deformation speed of the material when it is impacted. Summary of the invention

[0005] The purpose of the present invention is to provide a dynamic hardness testing device and a testing method to conveniently measure the dynamic hardness, which can better reflect the recovery deformation speed of the material when it is impacted compared with the static hardness.

[0006] According to one purpose of the present invention, the present invention provides a dynamic hardness testing device, including a loading sleeve, a guide tube, an escapement rod and a monitoring device, wherein a support seat is fixed to the bottom end of the guide tube, the top end of the guide tube is located at the inner layer of the bottom end of the loading sleeve and is slidably connected to the loading sleeve, the escapement rod penetrates the interior of the loading sleeve and the guide tube from top to bottom, an impact body is clamped at the bottom of the escapement rod, and a permanent magnet is arranged inside the impact body; the monitoring device is sleeved on the outer side of the bottom of the guide tube, an induction coil is arranged inside the monitoring device, and the induction coil is connected to an external test instrument through a wire.

[0007] Furthermore, a loading spring is provided inside the loading sleeve, and the loading spring is located between the top end of the guide tube and the loading sleeve. A spring fixing block for fixing the loading spring is provided at the top of the guide tube. A press button is provided at the top of the loading sleeve, and a reset spring is provided between the press button and the loading sleeve, and the bottom of the press button is fixedly connected to the top of the escapement rod.

[0008] Furthermore, a guide sleeve is provided inside the guide tube, and the guide sleeve is fixedly connected to the bottom end of the spring fixing block. A release spring is fixed to the bottom of the guide sleeve for clamping the impact body. The bottom of the escapement rod is slidably connected to the escapement hook, and an inclined slide groove is provided inside the escapement hook. The escapement rod can open the escapement hook by moving downward; a release spring is also provided at the bottom of the guide sleeve, and the release spring is located on the outside of the escapement hook. The release spring is installed between the guide sleeve and the impact body.

[0009] Furthermore, a rod sleeve is provided on the outside of the escapement rod, the escapement rod is slidably connected to the rod sleeve, and the rod sleeve is fixedly connected to the upper part of the loading sleeve.

[0010] Furthermore, the outer diameter of the spring fixing block is larger than the bottom opening diameter of the loading sleeve.

[0011] Furthermore, the escapement hook is located above the monitoring device.

[0012] Further, the stiffness coefficient of the loading spring is greater than the stiffness coefficient of the releasing spring.

[0013] Furthermore, the external test instrument is provided with a display screen and a command keyboard, the display screen displays the dynamic hardness value, impact body type, speed ratio, ΔT impact time and impact direction, and the external test instrument is provided with a storage module and a data transmission module.

[0014] According to another object of the present invention, the present invention provides a dynamic hardness testing method, comprising the following steps:

[0015] S1, the monitoring device is connected to an external test instrument, and the external test instrument is set with parameters;

[0016] S2, the support seat is pressed on the test interface of the test piece, and the measurement work starts after it is stable. The release button is pressed, the escapement hook opens and separates from the impact body, and the impact body is ejected under the action of the release spring. When the ejected impact body passes through the induction coil located in the monitoring device, the voltage generated by the permanent magnet in the impact body in the induction coil is proportional to the speed, so as to obtain the curve of impact speed and time;

[0017] S3, take the point where the maximum speed drops by 2%, and the point where the speed is 2% lower than the minimum speed, subtract them to get △T, and use the formula (3.5-△T) / 0.035 to get the dynamic hardness.

[0018] Furthermore, after the test is completed, the loading sleeve is pressed down, and the guide tube slides upward relative to the loading sleeve. At this time, the loading spring is compressed, and the escapement rod and the rod sleeve are driven downward. The release button is pressed to make the escapement hook open and hook the impact body, and the loading sleeve is released. At this time, the loading spring in a compressed state begins to rebound, and the escapement rod returns to its initial position under the action of the loading spring. The release spring is compressed during the rebound process, and the release button also returns to its initial position under the action of the reset spring.

[0019] The technical solution of the present invention uses a high-speed acquisition circuit to capture and record the speed change at the moment of impact when the magnetic impact body passes through the induction coil, and subtracts the point where the speed rebounds 2% from the maximum speed from the time point where the speed starts to drop 2%, to obtain the impact time △T. The impact time is used as the hardness measurement method, which can conveniently measure the dynamic hardness, and compared with the static hardness, it can better reflect the recovery deformation speed of the material when it is impacted. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is an operation flow chart of an embodiment of the present invention;

[0022] Figure 2 It is a structural schematic diagram of an embodiment of the present invention;

[0023] Figure 3 It is a schematic structural diagram of an escapement hook according to an embodiment of the present invention;

[0024] Figure 4 A schematic diagram of the structure of a test instrument according to an embodiment of the present invention;

[0025] In the figure, 1. loading sleeve; 2. guide tube; 3. escapement rod; 4. impact body; 5. loading spring; 6. spring fixing block; 7. press button; 8. guide sleeve; 9. escapement hook; 10. inclined slide; 11. release spring; 12. rod sleeve; 13. display screen; 14. command keyboard; 15. dynamic hardness value; 16. impact body type; 17. speed ratio; 18. △T impact time; 19. impact direction; 20. support seat; 21. reset spring. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Example 1

[0030] like Figure 2 and Figure 3 As shown,

[0031] A dynamic hardness testing device comprises a loading sleeve 1, a guide tube 2, an escapement rod 3 and a monitoring device, wherein a support seat 20 is fixed to the bottom end of the guide tube 2, the top end of the guide tube 2 is located in the inner layer of the bottom end of the loading sleeve 1 and is slidably connected to the loading sleeve 1, the escapement rod 3 penetrates the interior of the loading sleeve 1 and the guide tube 2 from top to bottom, an impact body 4 is clamped at the bottom of the escapement rod 3, and a permanent magnet is arranged inside the impact body 4; the monitoring device is sleeved on the outer side of the bottom of the guide tube 2, an induction coil is arranged inside the monitoring device, and the induction coil is connected to an external test instrument through a wire.

[0032] A loading spring 5 is provided inside the loading sleeve 1, and the loading spring 5 is located between the top of the guide tube 2 and the loading sleeve 1. A spring fixing block 6 for fixing the loading spring 5 is provided at the top of the guide tube 2, and the outer diameter of the spring fixing block 6 is larger than the bottom opening diameter of the loading sleeve 1. A pressing button 7 is provided at the top of the loading sleeve 1, and a reset spring 21 is provided between the pressing button 7 and the loading sleeve 1, and the bottom of the pressing button 7 is fixedly connected to the top of the escapement rod 3.

[0033] like Figure 3 As shown, a guide sleeve 8 is provided inside the guide tube 2, and the guide sleeve 8 is fixedly connected to the bottom end of the spring fixing block 6. A release hook 9 for clamping the impact body 4 is fixed to the bottom of the guide sleeve 8, and the release hook 9 is located above the monitoring device.

[0034] The bottom of the escapement rod 3 is slidably connected to the escapement hook 9, and an inclined slide groove 10 is provided inside the escapement hook 9. The escapement rod 3 moves downward to open the escapement hook 9; a release spring 11 is also provided at the bottom of the guide sleeve 8, and the stiffness coefficient of the loading spring 5 is greater than the stiffness coefficient of the release spring 11. The release spring 11 is located on the outside of the escapement hook 9, and the release spring 11 is installed between the guide sleeve 8 and the impact body 4.

[0035] A rod sleeve 12 is provided on the outside of the escapement rod 3 , the escapement rod 3 is slidably connected to the rod sleeve 12 , and the rod sleeve 12 is fixedly connected to the upper part of the loading sleeve 1 .

[0036] like Figure 4 As shown, the external test instrument is provided with a display screen 13 and a command keyboard 14. The display screen 13 displays a dynamic hardness value 15, an impact body type 16, a speed ratio 17, a △T impact time 18 and an impact direction 19. The external test instrument is provided with a storage module and a data transmission module.

[0037] like Figure 1 As shown, the present invention provides a dynamic hardness testing method, comprising the following steps:

[0038] S1, the monitoring device is connected to an external test instrument, and the external test instrument is set with parameters;

[0039] S2, the support seat is pressed on the test interface of the test piece, and the measurement work starts after it is stable. The release button is pressed, the escapement hook opens and separates from the impact body, and the impact body is ejected under the action of the release spring. When the ejected impact body passes through the induction coil located in the monitoring device, the voltage generated by the permanent magnet in the impact body in the induction coil is proportional to the speed, so as to obtain the curve of impact speed and time;

[0040] S3, take the point where the maximum speed drops by 2%, and the point where the speed is 2% lower than the minimum speed, subtract them to get △T, and use the formula (3.5-△T) / 0.035 to get the dynamic hardness.

[0041] After the test is completed, the loading sleeve is pressed down and the guide tube slides upward relative to the loading sleeve. At this time, the loading spring is compressed, and the escapement rod and the rod sleeve are driven downward. Press the release button to make the escapement hook open and hook the impact body, and release the loading sleeve. At this time, the loading spring in a compressed state begins to rebound, and the escapement rod returns to its initial position under the action of the loading spring. The release spring is compressed during the rebound process, and the release button also returns to its initial position under the action of the reset spring.

[0042] The present invention provides a new dynamic hardness test method. When the magnetic impact body passes through the induction coil, a high-speed acquisition circuit is used 100 times per millisecond to capture the speed change at the moment of impact and record it. The impact time △T is obtained by subtracting the point where the speed starts to drop by 2% from the point where it rebounds 2% from the maximum speed. After measuring a variety of materials, it is found that the impact speed of the softest rubber material does not exceed 3.5 milliseconds, and the impact speed of the hardest rubber is only 0.25 milliseconds, so (3.5-△T) / 0.035 is used to calculate the dynamic hardness, ranging from 0-100.

[0043] During the entire test process, the workpiece, the device and the operator should remain stable. If the value is obviously too high or too low during the test, the test value can be deleted and the rebound test can be performed again. When performing a dynamic hardness test, the impact direction can be in any direction, that is, the direction of the impact body can be in any direction.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing hardness using a dynamic hardness testing device, characterized in that: The following dynamic hardness testing device is used, including a loading sleeve, a guide tube, an escapement rod and a monitoring device, wherein a support seat is fixed to the bottom end of the guide tube, the top end of the guide tube is located at the inner layer of the bottom end of the loading sleeve and is slidably connected to the loading sleeve, the escapement rod penetrates the interior of the loading sleeve and the guide tube from top to bottom, the bottom of the escapement rod is clamped with an impact body, and a permanent magnet is arranged inside the impact body; the monitoring device is sleeved on the outer side of the bottom of the guide tube, and an induction coil is arranged inside the monitoring device, and the induction coil is connected to an external test instrument through a wire; the external test instrument is provided with a display screen and a command keyboard, and the dynamic hardness value, impact body type, speed ratio, △T impact time and impact direction are displayed on the display screen, and the external test instrument is provided with a storage module and a data transmission module; The steps include: S1, the monitoring device is connected to an external test instrument, and the external test instrument is set with parameters; S2, the support seat is pressed on the test interface of the test piece, and the measurement work starts after it is stable. The release button is pressed, the escapement hook opens and separates from the impact body, and the impact body is ejected under the action of the release spring. When the ejected impact body passes through the induction coil located in the monitoring device, the voltage generated by the permanent magnet in the impact body in the induction coil is proportional to the speed, so as to obtain the curve of impact speed and time; S3, take the point where the maximum speed drops by 2%, and the point where the speed is 2% lower than the minimum speed, subtract them to get △T, and use the formula (3.5-△T) / 0.035 to get the dynamic hardness; After the test is completed, the loading sleeve is pressed down and the guide tube slides upward relative to the loading sleeve. At this time, the loading spring is compressed, and the escapement rod and the rod sleeve are driven downward. The release button is pressed to make the escapement hook open and hook the impact body, and the loading sleeve is released. At this time, the loading spring in a compressed state begins to rebound, and the escapement rod returns to its initial position under the action of the loading spring. The release spring is compressed during the rebound process, and the release button also returns to its initial position under the action of the reset spring.

2. The method according to claim 1, characterized in that A loading spring is provided inside the loading sleeve, and the loading spring is located between the top end of the guide tube and the loading sleeve. A spring fixing block for fixing the loading spring is provided at the top of the guide tube. A pressing button is provided at the top of the loading sleeve, and a reset spring is provided between the pressing button and the loading sleeve, and the bottom of the pressing button is fixedly connected to the top of the escapement rod.

3. The method according to claim 2, characterized in that A guide sleeve is provided inside the guide tube, and the guide sleeve is fixedly connected to the bottom end of the spring fixing block. A release spring is fixed to the bottom of the guide sleeve for clamping the impact body. The bottom of the escapement rod is slidably connected to the escapement hook. An inclined slide groove is provided inside the escapement hook, and the escapement rod can open the escapement hook by moving downward. A release spring is also provided at the bottom of the guide sleeve, and the release spring is located on the outside of the escapement hook. The release spring is installed between the guide sleeve and the impact body.

4. The method according to claim 1, characterized in that: A rod sleeve is arranged outside the escapement rod, the escapement rod is slidably connected to the rod sleeve, and the rod sleeve is fixedly connected to the upper part of the loading sleeve.

5. The method according to claim 3, characterized in that: The outer diameter of the spring fixing block is larger than the bottom opening diameter of the loading sleeve.

6. The method according to claim 3, characterized in that The escapement hook is located above the monitoring device.

7. The method according to claim 3, characterized in that The stiffness constant of the loading spring is greater than the stiffness constant of the releasing spring.

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