A rebound hammer for field testing of compressive strength of concrete
By using a mechanical vertical calibration system and an ergonomically designed rebound hammer, the problem of relying on human judgment for verticality calibration in traditional rebound hammers has been solved, enabling high-precision and convenient testing of concrete compressive strength.
Patent Information
- Application Number
- CN202521970328.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-13
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-09-13
AI Technical Summary
When testing the compressive strength of concrete, traditional rebound hammers rely on human judgment for verticality calibration, which leads to large measurement errors. In particular, it is difficult to guarantee accuracy and ease of operation in low light or complex environments.
A rebound hammer with a socket frame, protective sleeve, observation glass, lighting, conical counterweight and magnetic block was designed. Through a mechanical vertical calibration system and ergonomic design, the instrument achieves self-contained vertical calibration and convenient operation, reducing human error.
It significantly reduces measurement errors caused by angular deviation and operational discomfort, improves testing accuracy and operational adaptability under different lighting conditions, and enhances instrument maintenance efficiency and user experience.
Smart Images
Figure CN224681933U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to non-destructive testing technology for concrete, specifically to a rebound hammer for on-site testing of concrete compressive strength. Background Technology
[0002] As the core structural material of building construction, concrete's compressive strength directly affects the safety and stability of buildings. In on-site testing of concrete quality, the rebound method has become a widely used testing method due to its non-destructive nature, ease of operation, and cost-effectiveness. This technology estimates the compressive strength of concrete by measuring the rebound value after the rebound hammer hits the concrete surface and combining it with a preset strength-rebound value relationship curve. With the advancement of building technology and the increasing requirements for engineering quality, the accuracy and ease of use of rebound hammers have become the focus of industry attention.
[0003] A core challenge currently facing rebound hammer technology lies in the contradiction between the accuracy of verticality calibration and ease of operation. Specifically, during the testing process, traditional rebound hammers require operators to rely on intuition or auxiliary tools to ensure that the instrument is absolutely perpendicular to the concrete surface. This process is not only time-consuming but also prone to human error, especially in low light or complex environments, where judging verticality becomes even more difficult, directly affecting the accuracy of the measurement results. Although existing technologies have attempted to improve this through external calibration devices or by increasing grip comfort, a built-in, self-contained vertical calibration system has not yet been achieved to fundamentally solve the problem of verticality calibration accuracy. This deficiency limits the widespread application of rebound hammers under different environmental conditions and the reliability of measurement results, thus requiring improvement. Utility Model Content
[0004] The purpose of this invention is to provide a rebound hammer for on-site testing of concrete compressive strength, in order to solve the problem of large measurement errors caused by reliance on human judgment for verticality calibration in the prior art.
[0005] To achieve the above objectives, this utility model provides the following technical solution: a rebound hammer for on-site testing of concrete compressive strength, comprising a rebound hammer body, a socket frame installed at one end of the rebound hammer body, a protective rubber sleeve installed on one side of the socket frame, and an elastic pad inserted into the inner wall of the protective rubber sleeve.
[0006] An observation glass is installed on the top of the socket frame, a fixing rod is installed on the bottom of the observation glass, a connecting rope is installed at the bottom end of the fixing rod, a conical counterweight is installed at the bottom end of the connecting rope, and multiple positioning rings are installed on the inner wall of the socket frame, with the positioning rings located below the conical counterweight.
[0007] Furthermore, lighting lamps are installed on both sides of the inner wall of the socket frame, and the lighting lamps are inclined downwards.
[0008] Furthermore, the output end of the rebounder body is equipped with a striking rod, one end of the striking rod is equipped with a connecting rod, and one end of the connecting rod is equipped with a positive magnetic block.
[0009] Furthermore, one end of the striking rod is provided with a striking head, one end of the striking head is provided with a insertion groove, and the inner wall of the insertion groove is sleeved on the surface of the insertion rod.
[0010] Furthermore, a negative magnetic block is installed on the inner wall of the insertion slot, and the negative magnetic block and the positive magnetic block are attracted and connected to each other.
[0011] Furthermore, a handle is installed at the bottom of the rebound device body, and grooves are provided on both sides of the handle.
[0012] Furthermore, a scale is installed on the top of the rebound device body.
[0013] Compared with existing technologies, this utility model provides a rebound hammer for on-site testing of concrete compressive strength. Through the setting of a connecting frame, protective rubber sleeve, elastic pad, observation glass, fixing rod, connecting rope, conical counterweight, positioning ring, and lighting, the operator can observe the relative position of the conical counterweight and positioning ring through the observation glass, intuitively and quickly adjust the instrument to an absolutely vertical state. The lighting ensures clear visibility of the indicators in dim environments. At the same time, the protective rubber sleeve and elastic pad effectively buffer the operating pressure, reducing hand fatigue. Thus, it achieves integrated vertical calibration and operation protection, significantly reducing measurement errors caused by angle deviation and operational discomfort, improving test accuracy and adaptability to different lighting conditions.
[0014] By incorporating a spring-loaded rod, a plug-in rod, a positive magnetic block, a spring-loaded head, a plug-in slot, a negative magnetic block, a handle, and a scale, the magnetic blocks attract each other and mechanically engage to enable quick and secure connection and manual replacement of the spring-loaded head. The ergonomic design of the handle provides a stable and comfortable grip, and the scale clearly indicates the rebound value. This achieves the effects of convenient replacement of the spring-loaded head to maintain a consistent measurement benchmark, comfortable and stable operation, and intuitive data reading, significantly improving instrument maintenance efficiency, user experience, and result reliability. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings.
[0016] Figure 1 A schematic diagram of the overall structure provided for an embodiment of this utility model;
[0017] Figure 2 This is a schematic diagram of the socket frame structure provided in an embodiment of the present utility model;
[0018] Figure 3 A schematic diagram of the positive magnetic block structure provided in an embodiment of this utility model;
[0019] Figure 4 This is a schematic diagram of the projectile head structure provided in an embodiment of the present utility model.
[0020] Explanation of reference numerals in the attached figures:
[0021] 1. Rebound hammer body; 2. Connecting frame; 3. Protective rubber sleeve; 4. Elastic pad; 5. Observation glass; 6. Fixing rod; 7. Connecting rope; 8. Conical counterweight; 9. Positioning ring; 10. Illumination lamp; 11. Impact rod; 12. Insertion rod; 13. Positive magnetic block; 14. Impact head; 15. Insertion slot; 16. Negative magnetic block; 17. Handle; 18. Scale. Detailed Implementation
[0022] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings.
[0023] As attached Figure 1 To be continued Figure 4 As shown:
[0024] Example 1:
[0025] This utility model provides a rebound hammer for on-site testing of concrete compressive strength, including a rebound hammer body 1, a socket frame 2 installed at one end of the rebound hammer body 1, a protective rubber sleeve 3 installed on one side of the socket frame 2, and an elastic pad 4 inserted into the inner wall of the protective rubber sleeve 3.
[0026] An observation glass 5 is installed on the top of the socket frame 2, a fixing rod 6 is installed on the bottom of the observation glass 5, a connecting rope 7 is installed at the bottom of the fixing rod 6, a conical counterweight 8 is installed at the bottom of the connecting rope 7, multiple positioning rings 9 are installed on the inner wall of the socket frame 2, and the positioning rings 9 are located below the conical counterweight 8. Lighting lamps 10 are installed on both sides of the inner wall of the socket frame 2, and the lighting lamps 10 are set at an angle downwards.
[0027] In use, a functional module integrating vertical calibration and operational protection is constructed through the socket frame 2 installed at one end of the rebound hammer body 1. The protective rubber sleeve 3 installed on one side of the socket frame 2 and the elastic pad 4 inserted into its inner wall are located at the rear of the instrument. Its core function is: when the operator presses the instrument backward with his palm to perform a flick, the protective rubber sleeve 3 provides a comfortable grip and anti-slip function, while the elastic pad 4 inside can effectively absorb and relieve the pressing pressure applied by the operator's palm, reduce hand fatigue, and thus protect the operator's hands. The observation glass 5 installed at the top of the socket frame 2 provides a sealed observation window. A connecting rope 7 is vertically suspended from the bottom of the fixed rod 6. A conical counterweight 8 is attached to the bottom end of the connecting rope 7, thus forming a purely mechanical gravity pendulum system. When the instrument tilts, under the influence of Earth's gravity, the conical counterweight 8 always points towards the Earth's center. Its tip shifts relative to the center position of the multi-layer positioning ring 9 installed on the inner wall of the socket frame 2. The operator can observe this by looking down through the observation glass 5, and the position of the tip of the conical counterweight 8 relative to the Earth's center will be determined by the relative position of the tip of the conical counterweight 8. The alignment of the innermost positioning ring 9's center allows for intuitive and precise judgment and adjustment of the instrument to an absolutely vertical state. This pendulum system is precisely constrained within the socket frame 2, and the length of the connecting rope 7 is precisely calculated to ensure that the swing trajectory of the conical counterweight 8 is strictly limited within the channel formed by the positioning ring 9 throughout its entire range of motion. Its maximum swing amplitude is much smaller than its distance from the bottom of the observation glass 5, thus fundamentally preventing the conical counterweight 8 from impacting or smashing into the observation glass 5 during operation, protecting the safety of the observation window. In addition, the downward-sloping lighting lamps 10 on both sides of the inner wall of the socket frame 2 can emit beams downwards in dim lighting conditions, illuminating the internal conical counterweight 8 and the scale of the positioning ring 9, ensuring that the pendulum indication is clearly visible under any working condition. This provides a built-in, self-contained, mechanical verticality indication and auxiliary lighting system for the operation of the rebound hammer, greatly reducing the angle error caused by the instrument's tilt operation, while improving operational comfort and adaptability to different lighting conditions.
[0028] Example 2:
[0029] This embodiment is basically the same as the previous embodiment, except that the output end of the rebounder body 1 is equipped with a striking rod 11, one end of the striking rod 11 is equipped with a connecting rod 12, one end of the connecting rod 12 is equipped with a positive magnetic block 13, one end of the striking rod 11 is provided with a striking head 14, one end of the striking head 14 is provided with a connecting groove 15, and the inner wall of the connecting groove 15 is sleeved on the surface of the connecting rod 12. The inner wall of the connecting groove 15 is equipped with a negative magnetic block 16, and the negative magnetic block 16 and the positive magnetic block 13 are mutually attracted and connected. The bottom of the rebounder body 1 is equipped with a handle 17, and both sides of the handle 17 are provided with grooves. The top of the rebounder body 1 is equipped with a scale 18.
[0030] In use, the striking rod 11, as the core component for force transmission, connects and separates quickly to the striking head 14 via a connecting rod 12. One end of the connecting rod 12 is embedded in a slot 15 at one end of the striking head 14. Precise mechanical fitting ensures coaxiality and linearity of force transmission after connection. To further ensure a secure connection and simplify operation, a positive magnetic block 13 is embedded at the end of the connecting rod 12, and a negative magnetic block 16 is embedded in the corresponding position on the inner wall of the slot 15. When the connecting rod 12 is inserted into the slot 15, the positive and negative magnetic blocks 13 attract each other under strong magnetic force, forming a robust magnetic locking mechanism. This mechanism effectively prevents the striking head 14 from loosening or falling off under frequent high impact loads, while also allowing the operator to... When the worn impact head 14 needs to be replaced, it can be quickly separated by simply applying a certain axial pulling force by hand to overcome the magnetic force, without any tools, which greatly improves the efficiency of on-site maintenance. The handle 17 installed at the bottom of the rebound hammer body 1 and the grooves on both sides are designed in strict accordance with ergonomics, providing the operator with a stable, non-slip and comfortable grip point, which is convenient for applying uniform and vertical pressing pressure. The scale 18 installed at the top of the rebound hammer body 1 is linked with the internal mechanical structure to directly and clearly indicate the rebound distance (i.e., rebound value) of the rebound hammer. It realizes three core functions: quick and reliable replacement of the impact head 14 to ensure long-term test accuracy, improved operating comfort and stability, and clear reading of measurement data, which significantly improves the instrument's practicality, maintenance convenience and the reliability of measurement results.
[0031] Application example:
[0032] The rail transit hub project has entered the main structure construction stage. To ensure that the project quality fully meets the design specifications, it is necessary to conduct large-scale on-site sampling inspections of the compressive strength of the poured concrete shear walls and frame columns. Traditional rebound hammer testing methods have revealed problems such as low operating efficiency, susceptibility to human factors, and inconvenience in such large-scale, high-intensity, and variable on-site operations. The project's quality inspection department has introduced a rebound hammer for on-site testing of concrete compressive strength as described in this utility model in order to improve the accuracy, efficiency, and ease of operation for personnel.
[0033] On the construction site on the second underground level of the hub station, workers first pre-treated the surface of the concrete shear wall in the area to be inspected. They used a grinding wheel to gently grind away the laitance and loose layer on the surface of the test area, and used a brush to remove dust, ensuring that the test surface was flat, clean, and dry. Subsequently, the workers took out the rebound hammer described in this utility model from the instrument case.
[0034] Before the testing began, the staff first checked the instrument's condition. The protective rubber sleeve 3 at the rear of the instrument and the built-in elastic pad 4 provided a soft and flexible grip, making it comfortable even for extended periods. The staff held the ergonomic handle 17 at the bottom of the instrument with one hand, using the other hand for support, and vertically pressed the impact head 14 against the center of the pre-marked test area. Before applying pressure for the test, the staff looked down at the top of the connecting frame 2 located above the instrument. Through the clear observation glass 5, the connecting rope 7 suspended by the fixing rod 6 and the conical counterweight 8 at its end could be clearly seen hanging naturally. The staff slightly adjusted the wrist angle until the tip of the conical counterweight 8 was precisely aligned with the center of the innermost positioning ring 9. At this point, the instrument was in the ideal vertical position. Although some areas of the working surface are poorly lit, the downward-sloping lights 10 on both sides of the inner wall of the socket frame 2 automatically turn on, and the soft light illuminates the scale of the internal conical counterweight 8 and positioning ring 9, ensuring that the pendulum indicator is clearly visible under any lighting conditions, providing a reliable guarantee for accurate alignment.
[0035] After confirming the instrument is vertical, the operator applies pressure evenly and vertically to the concrete surface. During the pressing process, the protective rubber sleeve 3 and elastic pad 4 at the tail effectively cushion the pressure on the palm, reducing fatigue caused by prolonged operation. When the pressure reaches the specified value, the impact rod 11 drives the impact head 14 to instantly impact the concrete surface and rebound. The operator clearly reads the rebound value using the scale 18 on the top of the instrument.
[0036] After completing tests at all test points in the area, staff discovered that the impact head 14 in that area showed slight wear due to frequent use. It was then replaced on-site. The replacement process was extremely simple: holding the impact head 14 by hand, applying slight force along the axis to overcome the magnetic force between the positive magnetic block 13 and the negative magnetic block 16, the old impact head 14 was pulled off the connector rod 12. Then, a brand new standard impact head 14 was taken out, its connector slot 15 was aligned with the connector rod 12, and it was gently pushed in. When the connector rod 12 was fully inserted into the connector slot 15, accompanied by a crisp "click," the positive magnetic block 13 and the negative magnetic block 16 were firmly attracted together, forming a secure connection. The entire replacement process required no tools, took very little time, effectively ensuring the continued accuracy of subsequent test data, and minimizing downtime due to maintenance.
[0037] Using this instrument, staff efficiently and accurately completed the random inspection of all designated components across a vast work area. The instrument's built-in vertical indication system fundamentally eliminated errors introduced by angular deviations, while the quick-change impact head design ensured the long-term consistency of the measurement benchmark. Furthermore, the user-friendly operating design significantly reduced workload. Ultimately, all test data was recorded promptly and accurately, providing a reliable basis for assessing the concrete construction quality of the main structure of this key project.
[0038] Working principle: The operator first holds the handle 17, which is installed at the bottom of the rebound hammer body 1 and has grooves on both sides. The striking head 14 at the front end of the striking rod 11 installed at the output end of the instrument is pressed against the concrete surface to be tested. Before applying pressure, the operator adjusts the instrument's attitude by observing the observation glass 5 installed at the top of the socket frame 2. A connecting rope 7 is vertically suspended by the fixing rod 6 installed at the bottom. A conical counterweight 8 is attached to the bottom of the connecting rope 7, thus forming a purely mechanical gravity pendulum system. When the instrument tilts, the conical counterweight 8 always points towards the center of the earth under the action of gravity, and its tip is relative to the socket frame 2. The center of the multi-layer positioning rings 9 installed on the inner wall of frame 2 shifts. The operator observes and adjusts through the observation glass 5 until the tip of the conical counterweight 8 coincides with the center of the innermost positioning ring 9. At this point, the instrument is in an absolutely vertical state. This pendulum system is precisely constrained inside the socket frame 2. The length of the connecting rope 7 is precisely calculated to ensure that the movement trajectory of the conical counterweight 8 is strictly limited within the channel formed by the positioning rings 9, and its maximum swing amplitude is much smaller than the distance to the bottom of the observation glass 5, fundamentally preventing the conical counterweight 8 from impacting the observation glass 5 during movement. If the ambient light is dim, the inside of the socket frame 2... The downward-sloping lights 10 on both sides of the wall will automatically illuminate, emitting beams of light to illuminate the scales of the conical counterweight 8 and the positioning ring 9, ensuring that the pendulum indicator is clearly visible. During vertical adjustment, the operator's palm presses on the protective rubber sleeve 3 installed on one side of the sleeve frame 2. The elastic pad 4 inserted into its inner wall can effectively absorb and relieve the pressure of the palm, reducing hand fatigue. After confirming that the instrument is vertical, the operator applies pressure evenly and vertically. After the impact rod 11 is pressed, it drives the impact head 14 to impact the concrete surface and rebound. The rebound value is clearly read through the scale 18 installed on the top of the rebound hammer body 1. Part 4 is a consumable part. When it wears out and needs replacement, the operator can quickly separate it by holding the impact head 14 by hand and applying force along the axis to overcome the magnetic force between the positive magnetic block 13 installed at one end of the plug rod 12 and the negative magnetic block 16 installed on the inner wall of the plug groove 15 at one end of the impact head 14. Then, the plug groove 15 of the new impact head 14 is aligned with the plug rod 12 installed at one end of the impact rod 11 and pushed in. The positive magnetic block 13 and the negative magnetic block 16 attract each other to form a solid connection. The precise mechanical fitting ensures the coaxiality of the connection and the linearity of force transmission, thus completing the quick replacement. The entire working process ensures zero error in the test angle through the integrated vertical calibration system, maintains the long-term uniformity of the measurement benchmark through the magnetic quick-change structure, and improves the comfort and efficiency of operation through ergonomic design, thereby significantly improving the accuracy, reliability and convenience of on-site testing.
[0039] The foregoing description only illustrates certain exemplary embodiments of the present invention. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A rebound hammer for on-site testing of concrete compressive strength, comprising a rebound hammer body (1), characterized in that, A socket frame (2) is installed at one end of the main body (1) of the rebounder, and a protective rubber sleeve (3) is installed on one side of the socket frame (2). An elastic pad (4) is inserted into the inner wall of the protective rubber sleeve (3). The top of the socket frame (2) is equipped with an observation glass (5), the bottom of the observation glass (5) is equipped with a fixing rod (6), the bottom end of the fixing rod (6) is equipped with a connecting rope (7), the bottom end of the connecting rope (7) is equipped with a conical counterweight (8), and the inner wall of the socket frame (2) is equipped with multiple positioning rings (9), and the positioning rings (9) are located below the conical counterweight (8).
2. A rebound hammer for on-site testing of concrete compressive strength according to claim 1, characterized in that, Lighting lamps (10) are installed on both sides of the inner wall of the socket frame (2), and the lighting lamps (10) are set at an angle downward.
3. A rebound hammer for on-site testing of concrete compressive strength according to claim 1, characterized in that, The rebounder body (1) is equipped with a striking rod (11) at its output end. A plug rod (12) is installed at one end of the striking rod (11), and a positive magnetic block (13) is installed at one end of the plug rod (12).
4. A rebound hammer for on-site testing of concrete compressive strength according to claim 3, characterized in that, One end of the striking rod (11) is provided with a striking head (14), and one end of the striking head (14) is provided with a insertion groove (15), and the inner wall of the insertion groove (15) is sleeved on the surface of the insertion rod (12).
5. A rebound hammer for on-site testing of concrete compressive strength according to claim 4, characterized in that, The inner wall of the insertion slot (15) is equipped with a negative magnetic block (16), and the negative magnetic block (16) and the positive magnetic block (13) are mutually attracted and connected.
6. A rebound hammer for on-site testing of concrete compressive strength according to claim 1, characterized in that, The bottom of the rebounder body (1) is equipped with a handle (17), and grooves are provided on both sides of the handle (17).
7. A rebound hammer for on-site testing of concrete compressive strength according to claim 1, characterized in that, A scale (18) is installed on the top of the rebounder body (1).