A building wall crack detection device

Abstract

The application provides a building wall crack detection device, and relates to the field of wall crack detection. The device comprises a crack detector, the bottom of the crack detector is provided with a fixing plate, a pair of sliding grooves are formed in the bottom wall of the fixing plate, sliding blocks are horizontally arranged in the sliding grooves, clamps are fixedly arranged on the sliding blocks, clamping assemblies are arranged between the sliding blocks and the fixing plate, so that the two clamps can clamp the wrists of the detection personnel, and adjusting assemblies are arranged between the probe part of the crack detector and the fixing plate, so as to adjust the position of the probe part. The application has the effect of facilitating observation of detection data.

Description

TECHNICAL FIELD

[0001] The application relates to the field of wall crack detection, in particular to a building wall crack detection device. BACKGROUND

[0002] The wall mainly includes load-bearing walls and non-load-bearing walls and mainly plays a role of enclosure and space separation. The wall of a wall-bearing structure building is combined with bearing and enclosure, and the role of the wall of a skeleton structure system building is to enclose and separate space. The wall should have sufficient strength and stability and have the ability of heat preservation, heat insulation, sound insulation, fireproofing and waterproofing.

[0003] However, the wall is prone to cracks due to long-term exposure to wind and sunlight. Wall cracks are cracking phenomena of the wall part of a building structure. According to the difference of the material itself, the wall cracks can be divided into concrete wall cracks, brick wall cracks, new type of partition wall cracks and cracks of walls made of different materials.

[0004] Once cracks occur, a crack detector is generally used to detect the width or depth of the cracks. The traditional detection method is to place two probes of the crack detector at the cracks of the wall for detection.

[0005] However, the detection method requires the operator to hold one probe in each hand and contact the wall, so that the crack detector can only be placed on the ground or hung on the operator's body, which is not conducive to the observation of the detection data by the detection personnel. SUMMARY

[0006] In order to improve the problem that the detection personnel cannot easily observe the detection data, the application provides a building wall crack detection device.

[0007] The application provides a building wall crack detection device, which adopts the following technical scheme:

[0008] The building wall crack detection device comprises a crack detector, a fixing plate is installed at the bottom of the crack detector, a pair of sliding grooves are formed in the bottom wall of the fixing plate, sliding grooves are horizontally arranged in the sliding grooves, clamps are fixedly arranged on the sliding blocks, clamping assemblies are arranged between the sliding blocks and the fixing plate, so that the two clamps can clamp the wrists of the detection personnel, and adjusting assemblies are arranged between the probe part of the crack detector and the fixing plate, so as to adjust the position of the probe part.

[0009] By adopting the above technical scheme, the wrist is placed between the two clamps, and then the two clamps are pushed close to each other until the wrist is wrapped and clamped, and the clamping assembly can ensure that the clamps clamp the wrist, so that the crack detector can be stably placed on the wrist, and the detection personnel can observe the data detected by the crack detector; and the adjusting assembly can be controlled by one hand to adjust the position of the probe part, thereby facilitating the detection of cracks.

[0010] Optionally, the clamping assembly comprises a clamping part and an unlocking part, the clamping part comprises a rack, a gear, a ratchet and a pawl, an inner top wall of the sliding groove is provided with a mounting groove, the rack is fixed on the sliding block, the gear and the ratchet are both rotatably installed in the mounting groove through a rotating shaft, the gear is engaged with the rack, the pawl is fixed in the mounting groove and cooperates with the ratchet, and the unlocking part is arranged between the pawl and the fixed plate.

[0011] By adopting the above technical scheme, after the two clamps clamp the wrist, the pawl and the ratchet limit the rotating shaft, and the rotating shaft can only rotate in one direction, so the two clamps are not easy to separate, thereby always clamping the wrist to improve the stability of placing the crack detector.

[0012] Optionally, the unlocking part comprises a moving block, a push rod and a sleeved spring, an inner top wall of the mounting groove is provided with a containing groove, the moving block is slidingly connected in the containing groove and slides in the horizontal direction, the pawl is fixed on the moving block, one end of the push rod is fixed with the moving block and the other end of the push rod protrudes outwardly through the fixed plate, the sleeved spring is sleeved on the push rod and one end of the sleeved spring is fixed with the inner side wall of the containing groove and the other end of the sleeved spring is fixed with the push rod.

[0013] By adopting the above technical scheme, if it is necessary to take down the crack detector, the push rod is pressed into the containing groove to push the moving block to move in the containing groove, so that the pawl and the ratchet are separated to not limit the rotating shaft; then the two clamps are moved away from each other, and the crack detector can be taken off from the wrist.

[0014] Optionally, the clamping part further comprises a reset spring, and the reset spring is fixed between the inner side wall of the sliding groove and the sliding block.

[0015] By adopting the above technical scheme, after the pawl and the ratchet are separated, the elastic force of the reset spring is released, so as to push the two clamps to automatically move away from each other until the distance between the two clamps is the maximum distance, and the two clamps do not need to be manually moved away from each other.

[0016] Optionally, the adjusting assembly comprises a rotating part, the rotating part comprises a rotating rod, a screw rod, a sliding block and a threaded cylinder, the threaded cylinder is rotatably installed on the fixed plate and penetrates the fixed plate, the rotating rod is rotatably installed on the crack detector, a bottom wall of the rotating rod is provided with a placing groove, the probe part is installed on the rotating rod, the sliding block is slidably connected in the placing groove and slides along the length direction of the placing groove, one end of the screw rod is hingedly connected with the sliding block and the other end is threadedly connected in the threaded cylinder.

[0017] By using the above technical scheme, the threaded cylinder can be rotated forward and backward, so as to drive the screw rod to move up and down in the vertical direction, thereby driving the sliding block to slide in the placing groove, so as to change the angle of the rotating rod to a certain extent, thereby changing the angle of the probe part to a suitable angle, so as to adapt to the crack detection.

[0018] Optionally, the adjusting assembly further comprises a pulling part, the pulling part comprises a connecting rod, a pulling rope, a connecting spring, a pulling belt and a fixing rod, a side wall of the rotating rod is provided with a connecting groove, end portions of the connecting rod are slidably connected in the connecting groove and slide along the length direction of the connecting groove, the probe part is installed on the connecting rod, the connecting spring is fixed between the inner wall of the connecting groove and the connecting rod, one end of the pulling rope is fixed with the connecting rod and the other end penetrates the connecting spring and outwardly extends through the rotating rod, one end of the pulling belt is fixed with the pulling rope and the other end penetrates the fixed plate, a plurality of locking holes are provided in the pulling belt, and the fixing rod is fixed to the bottom of the fixed plate and penetrates any locking hole.

[0019] By using the above technical scheme, the pulling belt can be pulled downward by the hand, the pulling rope will pull the connecting rod, so that the two connecting rods will approach each other to change the distance between the two probes, so as to adjust to a suitable position, thereby facilitating the detection of the crack.

[0020] Optionally, the rubber pads are fixedly arranged on opposite sides of the two clamps.

[0021] By using the above technical scheme, the rubber pads not only do not easily cause pain to the wrist when the two clamps are clamped on the wrist, but also can increase the friction between the clamps and the wrist, thereby improving the stability of the crack detector when clamped on the wrist.

[0022] Optionally, a recording assembly is arranged on the crack detector to record the detection data.

[0023] By using the above technical scheme, the detection data can be recorded by the recording assembly to prevent the detection data from being lost, and if the detection data needs to be viewed later, the data on the recording assembly can be directly viewed.

[0024] Optionally, the recording component comprises a receiving plate, a recording paper and a writing pen, the receiving plate is fixed on the side of the crack detector, the recording paper is fixed on the receiving plate through a connecting piece, and the writing pen is hung on the receiving plate through a string.

[0025] By adopting the above technical scheme, the writing pen can be used to record the detection data on the recording paper, so as to prevent the detection data from being lost and to be directly viewed subsequently; after the wall crack detection is completed, the recording paper can be pulled down from the connecting piece, so that the new recording paper is exposed.

[0026] Optionally, the connecting piece is a bolt, and the connecting piece penetrates the recording paper and is threadedly fixed on the receiving plate.

[0027] By adopting the above technical scheme, the connecting piece can be taken off from the receiving plate, so that the new recording paper can be fixed.

[0028] In summary, the present application has at least one of the following beneficial effects:

[0029] 1. The wrist is placed between the two clamps, and then the two clamps are pushed towards each other until the wrist is wrapped and clamped, and the clamping assembly can ensure that the clamps clamp the wrist, so that the crack detector can be stably placed on the wrist, so that the detection personnel can observe the data detected by the crack detector.

[0030] 2. The rubber pad not only does not easily cause pain to the wrist when the two clamps clamp the wrist, but also can increase the friction between the clamps and the wrist, thereby improving the stability of the crack detector when clamped on the wrist.

[0031] 3. The connecting piece can be taken off from the receiving plate, so that the new recording paper can be fixed. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic perspective view of a building wall crack detection device according to an embodiment of the present application;

[0033] Figure 2 is a schematic front view of Figure 1 ;

[0034] Figure 3 is a schematic sectional view taken along the section line A-A in Figure 2 ;

[0035] Figure 4 is a schematic partial enlarged view of the B part in Figure 3 ;

[0036] Figure 5 isFigure 1 schematic rear view.

[0037] In the figure: 1, crack detector; 11, probe part; 2, fixed plate; 21, sliding groove; 211, sliding block; 22, clamp; 221, rubber pad; 23, accommodating groove; 24, installation groove; 3, clamping part; 31, rack; 32, gear; 33, ratchet; 34, pawl; 35, return spring; 4, unlocking part; 41, moving block; 42, push rod; 43, sleeving spring; 5, rotating part; 51, rotating rod; 511, placing groove; 512, connecting groove; 52, screw rod; 53, sliding block; 54, threaded cylinder; 6, pulling part; 61, connecting rod; 62, pull rope; 63, connecting spring; 64, pulling belt; 641, locking hole; 65, fixed rod; 7, recording assembly; 71, receiving plate; 72, recording paper; 73, writing pen; 8, connecting piece; 9, rotating shaft. DETAILED DESCRIPTION

[0038] The embodiment of the application provides a building wall crack detection device.

[0039] Referring to Figure 1 , the building wall crack detection device can generally comprise a crack detector 1. In the embodiment of the application, the crack detector 1 is a crack detector 1 commonly sold on the market, so as to detect the width or depth of the wall crack.

[0040] Referring to Figure 2 , Figure 3 and Figure 4 , the crack detector 1 is fixedly installed at the bottom of the fixed plate 2, and the width of the fixed plate 2 is greater than the thickness of the crack detector 1. A pair of sliding grooves 21 are formed in the bottom wall of the fixed plate 2 and along the length direction, and sliding blocks 211 are horizontally and slidably arranged in the sliding grooves 21. In the embodiment of the application, the sliding grooves 21 and the sliding blocks 211 are both arranged in a "T" shape, so that the sliding blocks 211 are not easy to fall off from the sliding grooves 21.

[0041] Referring to Figure 3 and Figure 4 , the clamps 22 are fixedly arranged on the bottom wall of the sliding blocks 211. The initial state of the two clamps 22 is that the spacing between the two clamps 22 is maximum, and the opposite side of the two clamps 22 is concave, so as to be fitted with the wrist of the detection personnel. In addition, the rubber pads 221 are fixedly arranged on the concave side of the clamps 22. The rubber pads 221 not only do not easily cause pain to the wrist when the two clamps 22 clamp the wrist, but also can increase the friction between the clamps 22 and the wrist, thereby improving the stability of the crack detector 1 clamped on the wrist.

[0042] Referring to Figure 4The clamping assembly is arranged between the sliding block 211 and the fixed plate 2, before detection, the wrist can be placed between the two clamps 22, and then the two clamps 22 are pushed to be close to each other until the wrist is wrapped and clamped, and the clamping assembly can ensure that the clamps 22 clamp the wrist, so that the crack detector 1 can be stably placed on the wrist, so that the detection personnel can observe the data detected by the crack detector 1; and the two clamps 22 can adapt to different sizes of the wrist, so as to improve the applicability.

[0043] Referring to Figure 5 The probe part 11 of the crack detector 1 is provided with an adjusting assembly between the fixed plate 2, and in the embodiment of the application, the probe part 11 of the crack detector 1 has two probes, the adjusting assembly can facilitate the detection personnel to use the hand holding the crack detector 1 to adjust the distance and angle of the two probes, so that the width or depth of the crack can be detected more conveniently and accurately.

[0044] When detecting, the probe is attached to the wall body, and the width or depth of the crack can be detected.

[0045] Referring to Figure 1 Specifically, the side wall of the crack detector 1 is provided with a recording assembly 7, after the crack detector 1 detects data, the detection data can be recorded through the recording assembly 7, so as to prevent the detection data from being lost, and if the detection data needs to be viewed later, the data on the recording assembly 7 can be directly viewed.

[0046] Referring to Figure 1 The recording assembly 7 comprises a receiving plate 71, recording paper 72 and a writing pen 73, and the receiving plate 71 is fixed to the side wall of the crack detector 1. In the embodiment of the application, the recording paper 72 is provided with a plurality of sheets, and the recording paper 72 is fixed to the receiving plate 71 through a connecting piece 8, and the connecting piece 8 can be taken off from the receiving plate 71, so that the new recording paper 72 can be fixed.

[0047] Referring to Figure 1 The writing pen 73 is hung on the receiving plate 71 through a string, after the crack detector 1 detects data, the detection data can be recorded on the recording paper 72 by using the writing pen 73, so as to prevent the detection data from being lost, and the detection data can be directly viewed later; after the wall crack detection is completed, the recording paper 72 can be directly pulled off from the connecting piece 8, so that the new recording paper 72 is exposed.

[0048] Referring to Figure 1 In the embodiment of the application, the connecting piece 8 is a bolt, and the connecting piece 8 penetrates the recording paper 72 and is threadedly fixed to the receiving plate 71.

[0049] Referring to Figure 4 The clamping assembly comprises a clamping part 3 and an unlocking part 4.

[0050] Referring to Figure 4 , the clamping part 3 comprises a rack 31, a gear 32, a ratchet wheel 33 and a pawl 34, the inner top wall of the sliding groove 21 is provided with a mounting groove 24, the rack 31 is fixed to the top wall of the sliding block 211, the gear 32 and the ratchet wheel 33 are both rotatably installed in the mounting groove 24 through the rotating shaft 9 and are located above the rack 31, and the gear 32 is engaged with the rack 31. The pawl 34 is fixed to the inner top wall of the mounting groove 24, and the pawl 34 cooperates with the ratchet wheel 33, and through the cooperation of the pawl 34 and the ratchet wheel 33, the rotating shaft 9 can only rotate in one direction.

[0051] Before detection, the wrist is placed between the two clamps 22, and then the two clamps 22 are pushed close to each other, and in this process, the ratchet wheel 33 and the pawl 34 do not limit the rotating shaft 9 to ensure that the rotating shaft 9 can rotate; until the two clamps 22 clamp the wrist, so that the crack detector 1 can be stably placed on the wrist, so that the detection personnel can observe the detection data; and due to the limitation of the pawl 34 and the ratchet wheel 33 to the rotating shaft 9, the rotating shaft 9 can only rotate in one direction, therefore, the two clamps 22 are not easy to separate, so as to always clamp the wrist, thereby improving the stability of the crack detector 1.

[0052] Referring to Figure 4 , the unlocking part 4 comprises a moving block 41, a push rod 42 and a sleeved spring 43, the inner top wall of the mounting groove 24 is provided with a containing groove 23 along the width direction, the moving block 41 is slidingly connected in the containing groove 23 and slides in the horizontal direction, and the pawl 34 is fixed to the bottom wall of the moving block 41.

[0053] Referring to Figure 4 , the sleeved spring 43 is sleeved on one end of the push rod 42 located in the containing groove 23, one end is fixed to the inner side wall of the containing groove 23, and the other end is fixed to the side wall of the push rod 42. When it is necessary to take off the crack detector 1, the push rod 42 is pressed into the containing groove 23 to push the moving block 41 to move in the containing groove 23, so that the pawl 34 is separated from the ratchet wheel 33 to limit the rotating shaft 9; then the two clamps 22 are moved away from each other, and the crack detector 1 can be taken off from the wrist. In the embodiment of the application, the spring is provided between the pawl 34 and the moving block 41, but the pawl 34 is not pressed down and is always in a balanced state.

[0054] Referring to Figure 4In addition, the clamping portion 3 further comprises a reset spring 35, one end of the reset spring 35 is fixed to the side wall of the sliding block 211, and the other end is fixed to the inner side wall of the sliding groove 21. After the pawl 34 is separated from the ratchet wheel 33, the elastic force of the reset spring 35 is released, thereby pushing the two clamps 22 to automatically move away from each other until the distance between the two clamps 22 is the maximum distance, so as to place the two clamps 22 between the wrists of different sizes subsequently, thereby improving the applicability; and the two clamps 22 do not need to be manually moved away from each other.

[0055] Referring to Figure 5 , the adjusting assembly comprises a rotating portion 5 and a pulling portion 6.

[0056] Referring to Figure 5 , the rotating portion 5 comprises a rotating rod 51, a screw rod 52, a sliding block 53 and a threaded cylinder 54, the threaded cylinder 54 is rotationally installed on the fixed plate 2, and the threaded cylinder 54 is vertically arranged and penetrates through the fixed plate 2. The rotating rod 51 is rotationally installed on the crack detector 1, and two probes are respectively installed at two ends of the rotating rod 51. A placement groove 511 is formed in the bottom wall of the rotating rod 51 and extends along the length direction. The sliding block 53 is slidingly connected in the placement groove 511 and slides along the length direction of the placement groove 511.

[0057] Referring to Figure 5 , one end of the screw rod 52 is threadedly connected in the threaded cylinder 54, and the other end is hingedly connected to the bottom wall of the sliding block 53. After the crack detector 1 is fixed on the wrist, the threaded cylinder 54 can be reversibly rotated by the hand, so as to drive the screw rod 52 to move up and down in the vertical direction, thereby driving the sliding block 53 to slide in the placement groove 511, so as to change the angle of the rotating rod 51 to a certain extent, thereby changing the angle of the probe portion 11 to a suitable angle, so as to adapt to the crack detection.

[0058] Referring to Figure 5 , the pulling portion 6 comprises a connecting rod 61, a pulling rope 62, a connecting spring 63, a pulling belt 64 and a fixed rod 65. A connecting groove 512 is formed in the side of the rotating rod 51 away from the crack detector 1 and extends along the length direction, and two connecting grooves 512 are formed to correspond to the two probes. The end of the connecting rod 61 is slidingly connected in the connecting groove 512 and slides along the length direction of the connecting groove 512. The probe is fixed to the end of the connecting rod 61 away from the rotating rod 51.

[0059] Referring to Figure 5One end of the connecting spring 63 is fixed with the side wall of the one end of the connecting rod 61 located in the connecting groove 512, and the other end is fixed with the inner side wall of the connecting groove 512. One end of the pull rope 62 is fixed with the side of the connecting rod 61 close to the connecting spring 63, and the other end penetrates the connecting spring 63 and extends outward through the rotating rod 51. One end of the pulling belt 64 is fixed with the end of the pull rope 62 away from the connecting rod 61, and the other end penetrates the fixed plate 2. In the embodiment of the application, two pull ropes 62 are fixed with one pulling belt 64, and there is no need to set two pulling belts 64 corresponding to two pull ropes 62.

[0060] Referring to Figure 5 The side wall of the pulling belt 64 is provided with a plurality of locking holes 641 along the length direction, the fixed rod 65 is fixed to the bottom of the fixed plate 2, and the fixed rod 65 penetrates any locking hole 641, and the fixed rod 65 is in the shape of "L". After the crack detector 1 is fixed on the wrist, the hand can pull down the pulling belt 64, and the pulling belt 64 will pull the pull rope 62 to pull the connecting rod 61, so that the two connecting rods 61 will approach each other to change the distance between the two probes, so as to adjust to the appropriate position, thereby facilitating the detection of the crack.

[0061] The working principle of the building wall crack detection device of the application in use is as follows: before detection, the wrist is placed between the two clamps 22, and then the two clamps 22 are pushed to approach each other, and in this process, the ratchet wheel 33 and the pawl 34 do not limit the rotation of the rotating shaft 9, so as to ensure that the rotating shaft 9 can rotate; until the two clamps 22 clamp the wrist, so that the crack detector 1 can be stably placed on the wrist, so that the detection personnel can observe the detection data; and because the pawl 34 and the ratchet wheel 33 limit the rotation of the rotating shaft 9, the rotating shaft 9 can only rotate in one direction, therefore, the two clamps 22 are not easy to separate, so as to always clamp the wrist, thereby improving the stability of the crack detector 1.

[0062] The above are the preferred embodiments of the application, which do not limit the protection scope of the application, therefore: any equivalent changes made on the structure, shape and principle of the application shall be covered within the protection scope of the application.

Claims

1. A building wall crack detection device, characterized by, Include: The utility model provides a crack detector (1), the bottom of crack detector (1) is equipped with fixed plate (2), a pair of sliding groove (21) is opened to the bottom wall of fixed plate (2), and the sliding groove (21) is horizontally slidably arranged with sliding block (211), the clamping of two clamp (22) can be tightened to the wrist of the detection personnel, and the probe portion (11) of crack detector (1) is provided with adjusting assembly between fixed plate (2), so as to adjust the position of probe portion (11), the clamping assembly includes: clamping portion (3) and unlocking portion (4), the clamping portion (3) includes: rack (31), gear (32), ratchet (33) and pawl (34), the inner top wall of sliding groove is equipped with the accommodation groove (24), the rack (31) is fixed on the sliding block (211), gear (32) and ratchet (33) are rotatably installed in the accommodation groove (24) through rotating shaft (9), and the gear (32) is engaged with the rack (31), the pawl (34) is fixed in the accommodation groove (24), and the pawl (34) is matched with the ratchet (33), the unlocking portion (4) is arranged between the pawl (34) and fixed plate (2), the adjusting assembly includes: rotating portion (5), the rotating portion (5) includes: rotating rod (51), screw rod (52), sliding block (53) and threaded cylinder (54), threaded cylinder (54) rotatably installed on fixed plate (2) and penetrates fixed plate (2), rotating rod (51) rotatably installed on crack detector (1), and the bottom wall of rotating rod (51) is equipped with the accommodation groove (511), the probe portion (11) is installed on rotating rod (51), the sliding block (53) is slidably connected in the accommodation groove (511) and slides along the length direction of accommodation groove (511), and one end of screw rod (52) is hinged with sliding block (53), and the other end is threadedly connected in threaded cylinder (54).The adjusting assembly further comprises a pulling part (6), which comprises a connecting rod (61), a pulling rope (62), a connecting spring (63), a pulling belt (64) and a fixing rod (65); a side wall of the rotating rod (51) is provided with a connecting groove (512); an end of the connecting rod (61) is slidingly connected in the connecting groove (512) and slides along the length direction of the connecting groove (512); the probe part (11) is installed on the connecting rod (61); the connecting spring (63) is fixed between the inner wall of the connecting groove (512) and the connecting rod (61); one end of the pulling rope (62) is fixed with the connecting rod (61), the other end of the pulling rope (62) penetrates through the connecting spring (63) and outwardly extends through the rotating rod (51); one end of the pulling belt (64) is fixed with the pulling rope (62), the other end of the pulling belt (64) penetrates through the fixing plate (2), a plurality of locking holes (641) are penetratingly formed on the pulling belt (64); the fixing rod (65) is fixed on the bottom of the fixing plate (2) and penetrates through any locking hole (641).

2. The apparatus for detecting cracks in a building wall according to claim 1, wherein The unlocking part (4) includes: moving block (41), push rod (42) and set spring (43), the inner top wall of the arrangement groove (24) is provided with accommodating groove (23), the moving block (41) is connected in the accommodating groove (23) and along horizontal direction sliding, the pawl (34) is fixed on the moving block (41), one end of the push rod (42) is fixed with the moving block (41), the other end is penetrated through the fixed plate (2) and extends outward, the set spring (43) is set on the push rod (42) and one end is fixed with the inner side wall of the accommodating groove (23), the other end is fixed with the push rod (42).

3. The apparatus for detecting cracks in a building wall according to claim 2, wherein The clamping part (3) further comprises: reset spring (35), the reset spring (35) is fixed between the inner side wall of the sliding groove (21) and the sliding block (211).

4. The apparatus for detecting cracks in a building wall according to claim 1, wherein Two clamps (22) are fixed with rubber pads (221) on opposite sides.

5. The apparatus for detecting cracks in a building wall according to claim 1, wherein The crack detector (1) is provided with a recording assembly (7) for recording detection data.

6. The apparatus for detecting cracks in a building wall according to claim 5, wherein The recording assembly (7) includes: receiving plate (71), recording paper (72) and writing pen (73), the receiving plate (71) is fixed on the side of the crack detector (1), the recording paper (72) is fixed on the receiving plate (71) through the connecting piece (8), the writing pen (73) is hung on the receiving plate (71) through the string.

7. The apparatus for detecting cracks in a building wall according to claim 6, wherein The connecting piece (8) is a bolt, the connecting piece (8) penetrates the recording paper (72) and is screwed on the receiving plate (71).

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