Steel bar protective layer thickness measuring device

Abstract

The invention relates to the technical field of measurement, and particularly discloses a steel bar protective layer thickness measuring device which comprises a measurer body, a protection mechanism used for protecting the measurer body is arranged at the bottom of the exterior of the measurer body, the protection mechanism comprises a shell, the shell is connected to the exterior of the measurer body in a sleeving mode, and the measurer body is provided with a through hole. The inner wall of the shell is fixedly connected with a rubber sleeve, the inner wall of the rubber sleeve is slidably connected with the outer wall of the measurer body, the outer wall of the shell is provided with an antifriction mechanism used for facilitating movement of the measurer body, and the antifriction mechanism comprises a fixing strip. Through cooperation of the protection mechanism and the antifriction mechanism, the measurer body is effectively protected, meanwhile, when a steel bar protection layer is measured, the problem that the measurer body is damaged due to friction on a wall surface or the ground is effectively avoided, and through cooperation of the protection mechanism and the antifriction mechanism, mobile measurement can be facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of measurement, and specifically to a device for measuring the thickness of steel bar protective layer. Background Art

[0002] In the prior art, during the use of the device for measuring the thickness of steel bar protective layer, the device is often worn or damaged due to frequent friction with the concrete structure surface or hard interfaces in the construction environment (such as the ground, wall surface, pile hole wall, etc.). For example, in the traditional sliding scale structure (such as components like the clamping strip and detection board), when inserted into the gap between the steel bar and the formwork or lowered along the pile hole, the contact surface made of metal or hard plastic is prone to friction with the rough concrete surface, resulting in blurred scales, deformation of the clamping strip, or failure of the guiding structure, affecting the measurement accuracy; for the electromagnetic induction type device, the probe is in long-term contact and sliding with the concrete surface, and its wear-resistant layer is easily worn, leading to a decrease in the stability of the electromagnetic signal. In addition, for some adjustable devices, during the frequent adjustment process, precision components such as the moving plate and screw rod generate mechanical friction with the fixed structure, accelerating the wear of the thread and the expansion of the component fitting gap; these problems not only increase the equipment maintenance cost but also may cause measurement data deviation, affecting the reliability of engineering quality inspection. Summary of the Invention

[0003] The purpose of the present invention is to provide a device for measuring the thickness of steel bar protective layer, which solves the problems raised in the background art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A device for measuring the thickness of steel bar protective layer, including a measuring instrument body, and a protection mechanism for protecting the measuring instrument body is arranged at the bottom of the outer part of the measuring instrument body;

[0005] The protection mechanism includes a housing, the housing is sleeved on the outer part of the measuring instrument body, a rubber sleeve is fixedly connected to the inner wall of the housing, and the inner wall of the rubber sleeve is slidably connected to the outer wall of the measuring instrument body;

[0006] A friction reduction mechanism for facilitating the movement of the measuring instrument body is arranged on the outer wall of the housing;

[0007] The friction reduction mechanism includes a fixed strip, the fixed strip is fixedly connected to the bottom of the outer wall of the housing, and steel balls for preventing the housing from rubbing against the wall surface are arranged inside the fixed strip;

[0008] A marking mechanism for marking the side of the measuring instrument body is arranged on the outer wall of the housing, and a pushing mechanism for pushing the marking mechanism is arranged on the outer wall of the housing.

[0009] Further, a fixing block is fixedly connected to the top of the front surface of the outer shell. An elastic band is fixedly connected inside the fixing block. A fixing frame is fixedly connected to the bottom of the front surface of the outer shell. One end of the elastic band away from the fixing block is connected to the outer wall of the elastic band through a magic tape.

[0010] Further, a magic tape hook surface is sewn to one end of the elastic band away from the fixing block, and a magic tape loop surface is arranged on the outer wall of the elastic band.

[0011] Further, a placement groove is formed at one end of the fixing strip. There are multiple steel balls, all of which are placed inside the placement groove. A plug block is threadedly connected to the inner wall of one end of the placement groove. A slot is formed at one end of the plug block away from the fixing strip.

[0012] Further, threads are arranged on the outer wall of the plug block, and threads are arranged on the inner wall of the placement groove. The threads arranged on the outer wall of the plug block match the threads arranged on the inner wall of the placement groove. There are two friction reduction mechanisms, which are symmetrically mirrored with respect to the vertical bisector of the outer shell.

[0013] Further, the marking mechanism includes a first fixing box fixedly connected to the outer wall of the outer shell. A first piston plate is hermetically and slidably connected to the inner wall of the first fixing box. On both sides of the first piston plate away from the outer shell, sliding blocks are fixedly connected. The outer walls of the sliding blocks are slidably connected to the side of the first fixing box away from the outer shell. Between one ends of the two sliding blocks away from the first piston plate and on the side close to each other, a first fixing box is fixedly connected. Inside one of the two sliding blocks, a rotating rod is rotatably connected to the end away from the outer shell. The rotating rod passes through the other sliding block and extends to the outside of the other sliding block. A hand crank turntable is fixedly connected to the end of the rotating rod outside the sliding block. A pressing plate is threadedly connected to the outer wall of the rotating rod between the two sliding blocks on the side close to each other. A limiting rod is fixedly connected between the two sliding blocks away from the outer shell and on the side close to each other. The inner part of the pressing plate is slidably connected to the outer wall of the limiting rod. The pressing plate and the limiting rod are both located inside the first fixing box. A sliding rod is slidably connected to the inside of the pressing plate. A clamping block is fixedly connected to one side of the sliding rod close to the vertical bisector of the two sliding blocks. A first tension spring is sleeved on the outer wall of the sliding rod. Both ends of the first tension spring are fixedly connected between the clamping block and the side of the pressing plate close to each other.

[0014] Further, a double - thread is arranged on the rotating rod between the two sliding blocks on the side close to each other. Threads are arranged inside the pressing plate and match the double - thread arranged on the outer wall of the rotating rod. There are two sliding rods, which are symmetrically mirrored with respect to the vertical bisector of the clamping block. The side of the clamping block away from the sliding rod is arc - shaped. There are two sliding rods, which are symmetrically mirrored with respect to the vertical bisector of the two sliding blocks.

[0015] Further, a through groove penetrating through the outside of the bottom of the protection box is provided at the top of the protection box, and there are four marking mechanisms, which are respectively fixedly connected to the four sides of the outer shell.

[0016] Further, a pushing mechanism for pushing the pressing plate in the first fixing box of the marking mechanism to slide is fixedly connected to the outer wall of the outer shell. The pushing mechanism includes a second fixing box, the inner wall of the second fixing box is hermetically slidably connected with a second piston plate, the bottom of the second piston plate is fixedly connected with a second tension spring, the bottom of the second tension spring is fixedly connected with the bottom inner wall of the second fixing box, a limiting frame is fixedly connected to the bottom inner wall of the second fixing box, the bottom of the side of the second fixing box is fixedly sleeved with an air delivery pipe, one end of the air delivery pipe away from the second fixing box is communicated with the inside of the first fixing box, a pushing rod is fixedly connected to the top of the limiting frame, and the outer wall of the pushing rod is slidably connected with the top of the second fixing box.

[0017] Further, there are three second tension springs, which are arranged in an equidistant array, and there are multiple air delivery pipes, and the first fixing boxes in the four marking mechanisms are communicated through the multiple air delivery pipes.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. Through the cooperation of the protection mechanism and the friction reduction mechanism, the present invention effectively realizes the protection of the measuring instrument body. At the same time, when measuring the steel bar protection layer, the problem that the measuring instrument body is damaged by friction on the wall surface or the ground is effectively avoided, and through the cooperation of the protection mechanism and the friction reduction mechanism, it is convenient to move and measure.

[0020] 2. Through the cooperation of the marking mechanism and the pushing mechanism, when detecting the thickness of the steel bar protection layer, the present invention can perform a cross-shaped marking on the trend of the steel bar, thereby facilitating the measurement of the steel bar protection side behind. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:

[0022] Figure 1 It is a front view structural diagram of a device for measuring the thickness of a steel bar protection layer according to the present invention;

[0023] Figure 2 It is a three-dimensional structural diagram of a front view of a device for measuring the thickness of a steel bar protection layer according to the present invention;

[0024] Figure 3 It is a three-dimensional structural diagram of a rear view of a device for measuring the thickness of a steel bar protection layer according to the present invention;

[0025] Figure 4 The measuring device for the thickness of the steel bar protective layer of the present invention is Figure 3 The enlarged three-dimensional structure schematic diagram at A in

[0026] Figure 5 The three-dimensional structure schematic diagram of the cross-section of the first fixed box of the measuring device for the thickness of the steel bar protective layer of the present invention;

[0027] Figure 6 The three-dimensional structure schematic diagram inside the protective box of the measuring device for the thickness of the steel bar protective layer of the present invention;

[0028] Figure 7 The three-dimensional structure schematic diagram of the pushing mechanism of the measuring device for the thickness of the steel bar protective layer of the present invention.

[0029] In the figure:

[0030] 1. Measuring device body; 2. Protection mechanism; 21. Outer shell; 22. Rubber sleeve; 23. Fixed block; 24. Elastic band; 25. Fixed frame; 3. Friction reduction mechanism; 31. Fixed strip; 32. Placing groove; 33. Steel ball; 34. Plug block; 35. Slot; 4. Marking mechanism; 41. First fixed box; 42. First piston plate; 43. Sliding block; 44. Rotating rod; 45. Hand-cranked turntable; 46. Limiting rod; 47. Extrusion plate; 48. Sliding rod; 49. First tension spring; 410. Clamping block; 411. Protection box; 5. Pushing mechanism; 51. Second fixed box; 52. Second piston plate; 53. Limiting frame; 54. Pushing rod; 55. Second tension spring; 56. Air supply pipe. Specific embodiments

[0031] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0032] As Figures 1 to 7 shown, the present invention provides a technical solution: a measuring device for the thickness of a steel bar protective layer, including a measuring device body 1, and a protection mechanism 2 for protecting the measuring device body 1 is arranged at the outer bottom of the measuring device body 1;

[0033] The protection mechanism 2 includes an outer shell 21, the outer shell 21 is sleeved outside the measuring device body 1, a rubber sleeve 22 is fixedly connected to the inner wall of the outer shell 21, and the inner wall of the rubber sleeve 22 is slidably connected to the outer wall of the measuring device body 1;

[0034] A friction reduction mechanism 3 for facilitating the movement of the measuring device body 1 is arranged on the outer wall of the outer shell 21;

[0035] The friction reduction mechanism 3 includes a fixed strip 31, the fixed strip 31 is fixedly connected to the bottom of the outer wall of the housing 21, and steel balls 33 for preventing the housing 21 from rubbing against the wall are arranged inside the fixed strip 31;

[0036] A marking mechanism 4 for marking the side of the measuring instrument body 1 is arranged on the outer wall of the housing 21, and a pushing mechanism 5 for pushing the marking mechanism 4 is arranged on the outer wall of the housing 21.

[0037] A fixed block 23 is fixedly connected to the top of the front surface of the housing 21, an elastic band 24 is fixedly connected inside the fixed block 23, a fixed frame 25 is fixedly connected to the bottom of the front surface of the housing 21, one end of the elastic band 24 away from the fixed block 23 is connected to the outer wall of the elastic band 24 through a magic tape, a magic tape hook surface is sewn on the end of the elastic band 24 away from the fixed block 23, and a magic tape loop surface is arranged on the outer wall of the elastic band 24.

[0038] A placement groove 32 is formed at one end of the fixed strip 31. There are multiple steel balls 33, and they are all placed inside the placement groove 32. A plug block 34 is threadedly connected to the inner wall of one end of the placement groove 32. A slot 35 is formed at the end of the plug block 34 away from the fixed strip 31. Threads are arranged on the outer wall of the plug block 34, threads are arranged on the inner wall of the placement groove 32, and the threads arranged on the outer wall of the plug block 34 match the threads arranged on the inner wall of the placement groove 32. There are two friction reduction mechanisms 3, and they are mirror-symmetrical about the vertical bisector of the housing 21.

[0039] The marking mechanism 4 includes a first fixed box 41 which is fixedly connected to the outer wall of the housing 21. A first piston plate 42 is hermetically and slidably connected to the inner wall of the first fixed box 41. On both sides of the first piston plate 42 away from the housing 21, there are fixedly connected sliding blocks 43. The outer wall of the sliding block 43 is slidably connected to the side of the first fixed box 41 away from the housing 21. Between the ends of the two sliding blocks 43 away from the first piston plate 42 and on the side close to each other, there is fixedly connected a first fixed box 41. Inside one of the two sliding blocks 43, at the end away from the housing 21, there is a rotatably connected rotating rod 44. The rotating rod 44 passes through the other sliding block 43 and extends to the outside of the other sliding block 43. At the end of the rotating rod 44 outside the sliding block 43, there is fixedly connected a hand-cranked turntable 45. On the outer wall of the rotating rod 44 between the two sliding blocks 43 on the side close to each other, there is a screw-threaded connection with a pressing plate 47. Between the two sliding blocks 43 away from the housing 21 and on the side close to each other, there is fixedly connected a limiting rod 46. The inside of the pressing plate 47 is slidably connected to the outer wall of the limiting rod 46. Both the pressing plate 47 and the limiting rod 46 are located inside the first fixed box 41. Inside the pressing plate 47, there is a slidably connected sliding rod 48. On the side of the sliding rod 48 close to the mid-perpendicular of the two sliding blocks 43, there is fixedly connected a clamping block 410. The outer wall of the sliding rod 48 is sleeved with a first tension spring 49. The two ends of the first tension spring 49 are fixedly connected between the side of the clamping block 410 and the side of the pressing plate 47 close to each other.

[0040] There is a double-thread on the rotating rod 44 between the two sliding blocks 43 on the side close to each other. The inside of the pressing plate 47 is provided with a thread which matches the double-thread on the outer wall of the rotating rod 44. There are two sliding rods 48 which are mirror-symmetrical with respect to the mid-perpendicular of the clamping block 410. The side of the clamping block 410 away from the sliding rod 48 is arc-shaped. There are two sliding rods 48 which are mirror-symmetrical with respect to the mid-perpendicular of the two sliding blocks 43. The top of the protection box 411 is provided with a through groove penetrating through the outside of the bottom of the protection box 411. There are four marking mechanisms 4 which are respectively fixedly connected to the four sides of the housing 21.

[0041] On the outer wall of the housing 21, there is fixedly connected a pushing mechanism 5 for pushing the pressing plate 47 in the first fixed box 41 of the marking mechanism 4 to slide. The pushing mechanism 5 includes a second fixed box 51. A second piston plate 52 is hermetically and slidably connected to the inner wall of the second fixed box 51. The bottom of the second piston plate 52 is fixedly connected with a second tension spring 55. The bottom of the second tension spring 55 is fixedly connected to the bottom inner wall of the second fixed box 51. At the bottom inner wall of the second fixed box 51, there is fixedly connected a limiting frame 53. At the bottom side of the second fixed box 51, there is fixedly sleeved an air delivery pipe 56. The end of the air delivery pipe 56 away from the second fixed box 51 is communicated with the inside of the first fixed box 41. At the top of the limiting frame 53, there is fixedly connected a pushing rod 54. The outer wall of the pushing rod 54 is slidably connected to the top of the second fixed box 51.

[0042] There are three second tension springs 55, which are arranged in an equidistant array. There are multiple air supply pipes 56, and the first fixed boxes 41 in the four marking mechanisms 4 are connected through the multiple air supply pipes 56.

[0043] The working principle and usage process of the present invention are as follows: First, a protection mechanism 2 is provided outside the measuring instrument body 1. Inside the outer shell 21 of the protection mechanism 2, a rubber sleeve 22 is fixedly connected. The measuring instrument body 1 is placed inside the outer shell 21, and the outer shell 21 fixedly sleeved on the inner wall of the outer shell 21 can fix the measuring instrument body 1. Since the rubber sleeve 22 is soft, it can play a protective role. And in cooperation with the fixed block 23 fixed above the top of the outer shell 21, the elastic band 24 can be limited. At the same time, a fixed frame 25 is fixedly connected to the lower part of the outer shell 21. The elastic band 24 passes through the fixed frame 25. And since a magic tape is provided on the elastic band 24, the hook surface of the magic tape connected to the end of the elastic band 24 away from the fixed block 23 adheres to the loop surface connected to the elastic band 24, thereby facilitating the fixation of the measuring instrument body 1 and the outer shell 21, avoiding the problem of the outer shell 21 falling off. Therefore, the protection action is realized through the protection mechanism 2;

[0044] Through the provided anti-friction mechanism 3, in the anti-friction mechanism 3, a plurality of steel balls 33 are conveniently placed inside the fixed strip 31. And the outer wall of the plug block 34 is threadedly connected with the inner wall of the fixed strip 31. Therefore, it is convenient for the plug block 34 to block the placement groove 32. At the same time, through the slot 35, it is convenient to drive the rotation of the plug block 34. The thread provided on the outer wall of the plug block 34 and the thread provided on the inner wall of the placement groove 32 are set such that the plug block 34 automatically cannot rotate after each rotation until the bottom of the plug block 34 is flush with the bottom of the fixed strip 31, so that the bottom of the plug block 34 and the bottom of the fixed strip 31 always remain flush. Therefore, it is convenient to limit the steel balls 33. When the measuring instrument body 1 measures the steel bar protective layer, when the measuring instrument body 1 is moved, the protection mechanism 2 is driven to move. Due to the friction between the protection mechanism 2 and the ground or wall, etc., in cooperation with the anti-friction mechanism 3, this problem can be avoided;

[0045] Through the provided marking mechanism 4, four marking mechanisms 4 are respectively arranged on the side surface of the outer shell 21 and fixedly connected to the four sides of the outer shell 21 through four first fixing boxes 41. A first piston plate 42 is slidably connected inside the first fixing box 41. Thus, when the first piston plate 42 slides inside the sliding block 43, it can drive the two sliding blocks 43 to move away from or towards the outer shell 21. By placing a piece of chalk or a marker pen inside the through groove opened on the protection box 411, and by rotating the hand-cranked turntable 45, the hand-cranked turntable 45 drives the rotating rod 44 to rotate. When the rotating rod 44 rotates, it can control the two pressing plates 47 to move closer to or away from each other. When the two pressing plates 47 move closer to each other, they can drive the two clamping blocks 410 to move closer to each other, thus facilitating the two clamping blocks 410 to clamp the piece of chalk or the marker pen. With the tension of the first tension spring 49, it can clamp the piece of chalk or the marker pen and has a certain buffering effect, realizing the soft clamping function;

[0046] Through the provided pushing mechanism 5, the second fixing box 51 in the pushing mechanism 5 is fixed on the outer wall of the outer shell 21. By pressing the pushing rod 54, when the pushing rod 54 receives the pressing force, the pushing rod 54 can press the second tension spring 55. The second tension spring 55 moves downward under the extrusion force, so it is convenient to respectively transport the gas inside the second fixing box 51 to the inside of the first fixing box 41 through multiple air delivery pipes 56. Therefore, it can push the first piston plate 42 to move away from the outer shell 21, thus facilitating the driving of the piece of chalk or the marker pen to move on the wall surface. When the pushing rod 54 is released, the second tension spring 55 pushes the second piston plate 52 under the tension effect. Therefore, it effectively extracts air from the inside of the first fixing box 41 through multiple air delivery pipes 56, and then the first piston plate 42 can move towards the outer shell 21, thus realizing the marking with the piece of chalk or the marker pen. After marking four positions, it is convenient to connect the marks together.

[0047] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent replacements or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A device for measuring the thickness of the steel bar protection layer, comprising a measuring device body (1), characterized in that: A protection mechanism (2) for protecting the measuring instrument body (1) is provided at the outer bottom of the measuring instrument body (1); The protection mechanism (2) includes a housing (21). The housing (21) is sleeved outside the measuring instrument body (1). A rubber sleeve (22) is fixedly connected to the inner wall of the housing (21). The inner wall of the rubber sleeve (22) is slidably connected to the outer wall of the measuring instrument body (1); A friction reducing mechanism (3) for facilitating the movement of the measuring instrument body (1) is provided on the outer wall of the housing (21); The friction reducing mechanism (3) includes a fixing strip (31). The fixing strip (31) is fixedly connected to the bottom of the outer wall of the housing (21). Steel balls (33) for preventing the housing (21) from rubbing against the wall are arranged inside the fixing strip (31); A marking mechanism (4) for marking the side of the measuring instrument body (1) is provided on the outer wall of the housing (21), and a pushing mechanism (5) for pushing the marking mechanism (4) is provided on the outer wall of the housing (21).

2. The steel bar cover thickness measuring device according to claim 1, wherein: A fixing block (23) is fixedly connected to the top of the front surface of the housing (21). An elastic band (24) is fixedly connected inside the fixing block (23). A fixing frame (25) is fixedly connected to the bottom of the front surface of the housing (21). One end of the elastic band (24) away from the elastic band (24) is connected to the outer wall of the elastic band (24) through a magic tape.

3. The steel bar cover thickness measuring device according to claim 2, wherein: One end of the elastic band (24) away from the fixing block (23) is sewn with a hook surface of the magic tape, and a loop surface of the magic tape is provided on the outer wall of the elastic band (24).

4. A steel bar cover thickness measuring device according to claim 3, characterized in that: A placement groove (32) is opened at one end of the fixing strip (31). The steel balls (33) are multiple and are all placed inside the placement groove (32). A plug block (34) is threadedly connected to the inner wall of one end of the placement groove (32). A slot (35) is opened at one end of the plug block (34) away from the fixing strip (31).

5. The steel bar cover thickness measuring device according to claim 4, wherein: Threads are provided on the outer wall of the plug block (34), and threads are provided on the inner wall of the placement groove (32). The threads provided on the outer wall of the plug block (34) are matched with the threads provided on the inner wall of the placement groove (32). The friction reducing mechanism (3) is two and is symmetrically mirrored about the vertical bisector of the housing (21).

6. The steel bar cover thickness measuring device according to claim 5, characterized in that: The marking mechanism (4) includes a first fixed box (41), the first fixed box (41) is fixedly connected to the outer wall of the housing (21), the inner wall of the first fixed box (41) is hermetically and slidably connected with a first piston plate (42), both sides of the first piston plate (42) away from the housing (21) are fixedly connected with sliding blocks (43), the outer wall of the sliding blocks (43) is slidably connected with the side of the first fixed box (41) away from the housing (21), a protective box (411) is fixedly connected between the ends of the two sliding blocks (43) away from the first piston plate (42) and close to each other, one of the two sliding blocks (43) is rotatably connected with a rotating rod (44) at the end inside away from the housing (21), the rotating rod (44) penetrates through the other sliding block (43) and extends to the outside of the other sliding block (43), a hand-cranked turntable (45) is fixedly connected to the end of the rotating rod (44) outside the sliding block (43), an extrusion plate (47) is threadedly connected to the outer wall of the rotating rod (44) between the two sliding blocks (43) close to each other, a limiting rod (46) is fixedly connected between the two sliding blocks (43) away from the housing (21) and close to each other, the inner part of the extrusion plate (47) is slidably connected with the outer wall of the limiting rod (46), the extrusion plate (47) and the limiting rod (46) are both located inside the first fixed box (41), a sliding rod (48) is slidably connected to the inside of the extrusion plate (47), a clamping block (410) is fixedly connected to the side of the sliding rod (48) close to the perpendicular bisector of the two sliding blocks (43), a first tension spring (49) is sleeved on the outer wall of the sliding rod (48), and both ends of the first tension spring (49) are fixedly connected between the side of the clamping block (410) and the side of the extrusion plate (47) close to each other.

7. The steel bar cover thickness measuring device according to claim 6, characterized in that: A double-thread is provided on the rotating rod (44) between the two sliding blocks (43) close to each other, a thread is provided inside the extrusion plate (47) and is matched with the double-thread provided on the outer wall of the rotating rod (44), there are two sliding rods (48) and they are symmetrically arranged with respect to the perpendicular bisector of the clamping block (410), the side of the clamping block (410) away from the sliding rod (48) is arc-shaped, there are two sliding rods (48) and they are symmetrically arranged with respect to the perpendicular bisector of the two sliding blocks (43).

8. The steel bar cover thickness measuring device according to claim 7, characterized in that: A through groove is provided at the top of the protective box (411) and penetrates through the outside of the bottom of the protective box (411), there are four marking mechanisms (4) and they are respectively fixedly connected to the four sides of the housing (21).

9. The reinforcing bar cover thickness measuring device according to claim 8, wherein: The outer wall of the outer shell (21) is fixedly connected with a pushing mechanism (5) for pushing the pressing plate (47) in the marking mechanism (4) to slide inside the first fixing box (41). The pushing mechanism (5) includes a second fixing box (51). The inner wall of the second fixing box (51) is hermetically and slidably connected with a second piston plate (52). The bottom of the second piston plate (52) is fixedly connected with a second tension spring (55). The bottom of the second tension spring (55) is fixedly connected with the bottom inner wall of the second fixing box (51). The bottom inner wall of the second fixing box (51) is fixedly connected with a limiting frame (53). The bottom side of the second fixing box (51) is fixedly sleeved with an air supply pipe (56). One end of the air supply pipe (56) far from the second fixing box (51) is communicated with the inside of the first fixing box (41). The top of the limiting frame (53) is fixedly connected with a push rod (54). The outer wall of the push rod (54) is slidably connected with the top of the second fixing box (51).

10. The steel bar cover thickness measuring device according to claim 9, characterized in that: There are three second tension springs (55), and they are arranged in an equidistant array. There are multiple air supply pipes (56), and the first fixing boxes (41) in the four marking mechanisms (4) are communicated through the multiple air supply pipes (56).

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