KR102267076B1 - Multi slit marked crack gauge - Google Patents

Abstract

The present invention relates to a crack gauge for detecting cracks in a concrete structure, and includes a plurality of display parts 16 and concealment parts 25 on the inner plate 10 and the transparent outer plate 20, which are overlapping plates constituting the crack gauge, respectively. By forming in the form of an object spaced apart by an interval, and when the inner plate 10 and the outer plate 20 move relative to each other over a certain level, a plurality of display units 16 are displayed at once, so that the significance of cracking This is to enable immediate and clear confirmation of any changes.
Through the present invention, it is possible to quickly and simply grasp the fluctuation of the crack site of the structure to which the crack gauge is attached, thereby improving the efficiency and convenience of safety diagnosis of concrete structures including crack inspection.

Description

MULTI SLIT MARKED CRACK GAUGE {MULTI SLIT MARKED CRACK GAUGE}

The present invention relates to a crack gauge for detecting cracks in a concrete structure, and includes a plurality of display parts 16 and concealment parts 25 on the inner plate 10 and the transparent outer plate 20, which are overlapping plates constituting the crack gauge, respectively. By forming in the form of an object spaced apart by an interval, and when the inner plate 10 and the outer plate 20 move relative to each other over a certain level, a plurality of display units 16 are displayed at once, so that the significance of cracking This is to enable immediate and clear confirmation of any changes.

Cracks are a key indicator in judging the integrity of a concrete structure, and by detecting the size, location, and progression of cracks, the stability and performance of the concrete structure can be grasped.

In particular, the temporal change of crack state is essential information in diagnosing the long-term and short-term safety of a structure, and in most concrete structures, periodic inspection of crack occurrence points is performed.

Periodic detection of cracks in concrete structures is performed by attaching a crack gauge to the cracking site and observing it. This crack gauge is a measuring instrument composed of a pair of overlapping plate bodies, and is a related prior art in Patent No. 2083255 and the like.

The conventional crack gauge including Patent No. 2083255 is composed of a pair of plate bodies overlapping each other, as shown in FIG. 1 , and an inner plate 10 marked with a mark 92 and an outer plate made of a transparent material marked with a leader line 93 ( 20), and a fixing part 91 is formed at the rear end of each of the inner plate 10 and the outer plate 20, and these fixing parts 91 are attached to the surface of the concrete structure to be tested through an adhesive or the like.

That is, as shown in FIG. 1, by attaching crack gauges to the surfaces of both sides of the crack occurrence point of the concrete structure, the inner plate 10 is fixed on the surface of the structure at a point slightly spaced apart in one direction orthogonal to the linear crack. Attach the part 91 and attach the fixing part 91 of the outer plate 20 to the surface of the structure at a point slightly spaced apart in the other direction orthogonal to the linear crack, but the front end of the inner plate 10 (92) The display portion and the indicator line 93 of the front end of the outer plate 20 are overlapped with each other.

Therefore, by periodically checking the position of the leader line 93 of the outer plate 20 superimposed on the surface of the mark 92 mark of the inner plate 10, it is possible to grasp the change in crack width with time, thereby increasing the rate of crack expansion and whether the permissible value is reached. etc. can be checked.

As such, the conventional crack gauge as shown in FIG. 1 has the advantage of accurately grasping the progress of cracks generated in the concrete structure even with a relatively simple configuration consisting of a pair of plate bodies, but There is a limitation that the operation completely depends on the inspector's visual observation (肉眼).

That is, the conventional crack gauge visually reads the position of the leader line 93 marked on the transparent outer plate 20 on the surface of the mark 92 marked on the inner plate 10 at the overlapping portion of the inner plate 10 and the outer plate 20 . cracks are detected in this way, and since cracks in general concrete structures have very small fluctuations, it is impossible for an inspector to detect crack fluctuations immediately, closely observing the cracks close to the crack gauge or using a magnifying glass. Substantial measurement is possible only if auxiliary means such as such are used.

Therefore, it can be said that the conventional crack gauge can be operated normally only under the premise of close observation of the inspector, which causes various problems as follows.

First of all, in the conventional crack gauge, the inspector must visually check the position of the leader line 93 on the target 92, and it is immediately and There was a problem that it was difficult to quickly confirm.

That is, in the conventional crack gauge, the inspector must check the movement state of the leader line 93 on the target 92 by using a magnifying glass or the like in a state close to the crack gauge installation point. Not only is it difficult to check quickly, but detailed observation is required throughout the measurement process, which inevitably takes a considerable amount of time.

In particular, in the case of large-scale structures, separate crack gauges need to be installed at each of multiple cracks, and separate crack gauges are located at multiple points along the crack line for accurate identification of crack progress even in a single crack. is installed, the process of checking each crack gauge one by one inevitably takes a long time, which directly leads to a decrease in work efficiency and an increase in inspection cost.

In addition, as described above, the conventional crack gauge requires close observation of an inspector, and a high-altitude structure in which the inspector's free access may be restricted, a deep part in a narrow space of the structure, or In the case of floating structures, there is inevitably a significant difficulty in the inspection work, and there was a serious problem that the risk of an accident still exists during the work process.

The present invention was devised in view of the above problems, and a part of the tip of the inner plate 10 attached to one side of the cracked part of the structure and a part of the tip of the outer plate 20 attached to the other side of the cracked part overlap each other, so that the crack width In a crack gauge in which the overlapping portion is changed as the inner plate 10 and the outer plate 20 move relative to each other in the direction of variation of the crack width in a state in which the rear surface of the outer plate 20 is close to the inner plate 10 surface as this is changed, the inner plate (10) A background portion 15, which is a dark portion, is formed on the surface, and a display portion 16 that is a bright portion as an object orthogonal to the relative movement directions of the inner plate 10 and the outer plate 20 inside the background portion 15 ) Many are formed spaced apart at equal intervals, and on the outer plate 20 of a transparent material, a plurality of concealing units 25, which are dark objects in a direction parallel to the display unit 16, are formed spaced apart at equal intervals and between the concealing units 25. A plurality of the see-through portions 26 formed in the doedoe are spaced apart at equal intervals, and the separation interval of the display unit 16 and the separation interval of the see-through portion 26 are the same, so that the display portion 16 of the inner plate 10 and the outer plate 20 ), as the inner plate 10 and the outer plate 20 move relative to each other in a state in which the hiding portion 25 is overlapped, the display portion 16 of the inner plate 10 and the see-through portion 26 of the outer plate 20 overlap while the entire It is a multi-slit display type crack gauge characterized in that the display portion 16 is exposed at the same time.

In addition, a pair of guide walls 12 orthogonal to the relative movement direction of the inner plate 10 and the outer plate 20 are formed to be spaced apart from each other on the inner plate 10 , and the outer plate 20 side side surface between the guide walls 12 . The moving plate 40 on which the inclined surface 41 is formed is coupled to be able to slide freely in a direction parallel to the guide wall 12, and the angle between the inclined surface 41 and the adjacent guide wall 12 is 45 degrees. It is set to less than, and a protruding restraining plate 24 is formed at the tip of the outer plate 20, so that when the inner plate 10 and the outer plate 20 are overlapped and installed, the end of the restraining plate 24 is the moving plate 40. While in contact with the inclined surface 41, the movement of the moving plate 40 is inhibited, and as the contact point between the restraining plate 24 and the inclined surface 41 is changed according to the relative movement of the inner plate 10 and the outer plate 20, the moving plate ( 40) is a multi-slit display type crack gauge characterized by moving.

Through the present invention, it is possible to quickly and easily grasp the fluctuations of the cracked part of the structure to which the crack gauge is attached, thereby improving the efficiency and convenience of safety diagnosis of concrete structures including crack inspection.

In particular, it is possible to immediately check whether a crack has progressed beyond a certain level from a distance without close observation of the crack gauge, thereby dramatically improving the speed and convenience of inspection work.

In addition, since daily inspection of points where it is difficult for inspectors to approach, such as structures at height or water structures, can be performed from a distance, the burden of inspection work can be greatly reduced and accidents that may occur during inspection can be delayed This can be prevented to ensure work safety.

1 is a perspective view of a conventional crack gauge;
2 is a perspective view of the present invention;
3 is an explanatory view of the display state for each crack state of the present invention;
4 is an explanatory diagram of the main part of the present invention;
5 is an explanatory diagram of a display method of the present invention;
6 is an explanatory view of a display method according to an embodiment of the present invention to which a stepped display unit is applied.
7 is a perspective view of a modified embodiment of the present invention;
8 is a perspective view of an embodiment of the present invention to which a moving plate is applied;
Fig. 9 is an exploded perspective view showing the main part of the embodiment of Fig. 8;
Fig. 10 is an explanatory diagram of the operation method of the embodiment of Fig. 8;

The detailed configuration and operation of the present invention will be described with reference to the accompanying drawings.

First, Figure 2 is a perspective view showing the appearance of the present invention, as shown, the present invention is a crack gauge composed of a pair of plate bodies overlapping each other, the front end is marked with a mark 92 and the rear end is a fixing unit It is composed of an inner plate 10 having a 91 formed thereon, an outer plate 20 having a leader line 93 displayed on the front end and an anchoring part 91 formed on the rear end. The leader lines 93 of the outer plate 20 are attached and installed on the surface of the crack-generating concrete structure in a state of overlapping with each other.

In the present invention, the attachment of the crack-generating concrete structure of the inner plate 10 and the outer plate 20 includes the anchoring part 91 formed on the rear end of the inner plate 10 and the anchoring part 91 formed on the rear end of the outer plate 20, respectively. Based on the crack line, it is performed by binding using a bonding tool such as a concrete adhesive or screw at one point and the other point in the direction perpendicular to the crack line. Therefore, the installation of the crack gauge of the present invention for the cracked part of the concrete structure being inspected The inner plate 10 and the outer plate 20 are attached in the form of crossing a linear crack in a direction orthogonal or close to orthogonal to a state in which a portion of each tip portion is overlapped.

That is, in the present invention, a part of the tip of the inner plate 10 attached to one side of the cracked part of the structure and a part of the tip of the outer plate 20 attached to the other side of the cracked part overlap each other, and as the crack width fluctuates, the inner plate 10 As a crack gauge in which the overlapping portion is changed as the inner plate 10 and the outer plate 20 move relative to each other in the direction of change of the crack width in a state where the back surface of the outer plate 20 is close to the surface, as in FIGS. 2 and 3, the inner plate A background part 15 and a display part 16 are formed in 10, and a hiding part 25 and a see-through part 26 are formed on the transparent outer plate 20, and these display parts 16 and a see-through part 26 are formed. ), the visual display state is configured to change dramatically depending on the overlapping position.

The background part 15, the display part 16, the hiding part 25, and the see-through part 26 of the present invention are the inner plate 10 attached to one side of the crack of the structure under test and the outer plate 20 attached to the other side of the crack. As the relative movement moves, the overlapping state is changed and the bright part formed by the display part 16 and the see-through part 26 inside the dark part formed by the hiding part 25 and the background part 15 ) is dramatically displayed at once, so it can be said that the visibility is dramatically improved compared to the conventional method of using the standard mark 92 and leader line 93 in determining whether crack fluctuations above a certain level have occurred.

Here, the relative movement of the inner plate 10 and the outer plate 20 means the relative movement of the inner plate 10 or the outer plate 20 according to a change in the crack state such as enlargement or reduction of the crack width, and in a typical concrete structure When considering the applied crack detection method, the direction of relative movement is set in a direction perpendicular to or close to the crack line to reflect the increase or decrease of the crack width, and according to the relative movement direction set in this way, the inner plate constituting the crack gauge of the present invention ( 10) and the outer plate 20 are attached to one side and the other side of the crack line, respectively.

That is, considering that the overlap plate-shaped crack gauge including the present invention is installed in a direction perpendicular to the linear crack, the relative movement direction of the inner plate 10 or the outer plate 20 is the inner plate 10 or the outer plate 20. It can be said that it is its central axis direction, and in the relative movement of the inner plate 10 or the outer plate 20, only one of the inner plate 10 or the outer plate 20 can move depending on the progress of the crack. Of course, the crack width may increase or decrease while the inner plate 10 and the outer plate 20 move at the same time. In analyzing the behavior of the crack gauge, even if either one of the inner plate 10 and the outer plate 20 is in a stationary state, the other It is preferable to introduce the relative movement state of the inner plate 10 and the outer plate 20 so as to reflect the crack variation through the movement of the .

In the present invention, the background part 15 and the hiding part 25 formed as the dark part may be formed in the form of a printed layer, a coating layer of paint, or an adhesion layer of a thin film, and as shown in FIGS. 3 to 5, the inner plate ( 10) is formed on the surface of the background part 15, which is a dark part, and inside the background part 15, a display part that is a bright part as an object orthogonal to the relative movement direction of the inner plate 10 and the outer plate 20 described above. 16) Many are formed at equal intervals.

Here, as in the dictionary meaning, the dark part and the bright part represent the dark part and the bright part. The dark part is composed of a color with low brightness including black and high hiding power for the back part, and the bright part shows the brightness such as white or yellow. It is composed of colors that are high in color and have a clear contrast with the dark areas.

Therefore, when the inner plate 10 on which the background portion 15 is formed has a surface of a high-brightness color such as white, the portion excluding the portion where the display portion 16 is formed is formed by printing or painting the dark portion of the background portion 15 . It is also possible to form the display unit 16, which is a list, by printing or painting the color of the background unit 15 only.

In addition, as in FIGS. 3 and 5 , a plurality of concealing units 25 , which are dark objects in a direction parallel to the display unit 16 , are formed at equal intervals on the outer plate 20 of a transparent material, and the concealing units 25 . A plurality of the see-through units 26 formed therebetween are formed to be spaced apart at equal intervals, and as shown in FIG. 5 , the distance between the display unit 16 and the see-through unit 26 is set to be the same.

That is, as in FIG. 3 , in the inner plate 10 , a plurality of display units 16 are arranged at equal intervals inside the background part 15 which is a dark part, and in the outer plate 20 which is a transparent plate, between the concealing parts 25 which are dark parts. The transparent part 26 is repeatedly formed to form a multi-slit structure as a whole, and as shown in FIGS. 4 and 5 , the display part 16 of the inner plate 10 and the outer plate 20 are concealed. As the inner plate 10 and the outer plate 20 move relative to each other in the state where the portion 25 is overlapped, the display portion 16 of the inner plate 10 and the see-through portion 26 of the outer plate 20 overlap, and the entire display portion 16 ) are exposed simultaneously.

In forming the background part 15 , the display part 16 , the hiding part 25 and the see-through part 26 , parallax, refraction or distortion caused by the thickness of the outer plate 20 , which is an outer transparent plate, is prevented. In order to prevent this from occurring, the background part 15 and the display part 16, which are indicators of the rear part, are formed on the surface of the inner plate 10, and the concealment part 25, which is the display part of the surface part, is the back surface of the outer plate 20. It is preferable that the background portion 15, the display portion 16, and the hiding portion 25 be overlapped on the same plane without any thickness difference when they are overlapped.

Here, the width of the hiding part 25 is formed to be enlarged compared to the width of the see-through part 26 and the display part 16, so that when the movement of less than a certain level occurs in the relative movement process of the inner plate 10 and the outer plate 20, the display part ( 16) is suppressed and only when a movement exceeding a certain level occurs, the behavior of the entire display unit 16 is displayed at once, which is superior to the simple reference scale 92 and the leader line 93 overlapping method. It is possible to obtain an improved visual display effect.

That is, when the initial installation relative of the inner plate 10 and the outer plate 20 is maintained or the relative movement distance is small because the crack width expansion is insignificant, the background part 15, the display part 16, the hiding part 25 and the see-through part mentioned above. The overlapping state between (26) is formed as shown in the upper drawing of FIG. 4 and only the dark part is displayed, but as soon as the relative movement distance of the inner plate 10 and the outer plate 20 exceeds a certain level due to the expansion of the crack, a plurality of display parts (16) As the whole is displayed at once through a plurality of see-through parts 26, the list that encroaches on the area of the dark part is dramatically displayed as in the lower drawing of the same figure, so the inspector can quickly and easily grasp it it can be

The list formation according to the temporary display of the display unit 16 can be clearly confirmed only with the naked eye without the need to mobilize a magnifying glass, but also can be checked from a distance without proximity to the crack gauge. Structure maintenance work such as safety diagnosis It is possible not only to dramatically improve the convenience of work, but also to remarkably reduce the burden of work at a dangerous point such as a structure at high altitude, a narrow structure, or a water structure.

In addition, when performing periodic detection of a plurality of points to be inspected, first check whether the above-described display unit 16 is displayed from a distance, select a point where a change of a certain level or more has occurred, and then closely detect only the selected point It is also possible to introduce a method to perform the safety examination, which can dramatically improve the efficiency of the safety diagnosis task.

In particular, when exposing a reflector or applying a reflective or fluorescent paint in forming the display unit 16, which is a list, improved visibility can be provided. It is possible to check the method of checking the reflected light using the light source of the

6 shows that in forming the display unit 16 inside the background unit 15, the display unit 16 is formed in a stepped shape, thereby expressing crack fluctuations above a certain level, as shown in the lower part of the figure. Of course, even when the crack continues to progress, it is clearly displayed and at the same time, the degree of progress can also be confirmed through the change of the display position of the display unit 16 .

7 is an embodiment in which the installation positions of the background part 15 and the display part 16 formed on the inner plate 10 and the hiding part 25 formed on the outer plate 20 are changed, and in FIGS. 2 to 4 . In the embodiment, the background part 15 and the display part 16 are formed on the surface of the inner plate 10 , and a transparent extended part 30 protruding toward the inner plate 10 is formed at the front end of the outer plate 20 , and the extended part 30 is formed. ), but the concealed part 25 and the see-through part 26 were formed, but in the embodiment of FIG. 7, the front end of the inner plate 10 is partially protruded and expanded to constitute the expanded part 30, and the background part is on this expanded part 30 (15) and the display part 16 were formed, and the hiding part 25 and the see-through part 26 were formed inside the plate body of the outer plate 20 which is itself transparent.

7 through the embodiment of the inner plate 10, it is possible to utilize the space between the central portion and the rear end portion, thereby applying the moving plate 40 as in Figs. Visibility and precision can be secured at the same time.

That is, as in FIGS. 8 to 10 , the inner plate 10 has a pair of guide walls 12 orthogonal to the relative movement directions of the inner plate 10 and the outer plate 20 spaced apart from each other, and the guide wall 12 is formed. In between, the moving plate 40 having an inclined surface 41 formed on the side of the outer plate 20 is coupled so as to be able to slide freely in a direction parallel to the guide wall 12, and the tip of the outer plate 20 has a protruding The restraining plate 24 is formed, and the end of the restraining plate 24 is configured to be in contact with the inclined surface 41 of the moving plate 40, and the inclined surface 41 and the restraining plate 24 of the moving plate 40 are formed. The relative movement distance of the inner plate 10 and the outer plate 20 due to crack fluctuations is amplified through the movement direction change and movement distance amplification action between them and expressed as the active movement distance of the moving plate 40, so that more precise detection is possible will be.

8 and 9, the moving plate 40 coupled between the pair of guide walls 12 spaced apart from each other has a rectangular shape as a whole and has a frontal width between the pair of guide walls 12 spaced apart from each other. By matching the width of the space, the moving plate 40 coupled between the guide walls 12 can freely move up and down in the drawing, which is a direction parallel to the guide wall 12 .

In the embodiment shown in Figs. 8 to 10, the moving plate 40 performs an activity of descending by its own weight, and as shown in the same figure, the moving plate 40 by the restraining plate 24 of the outer plate 20 ( 40) As the inclined surface 41 of one side is supported in contact, the end of the restraining plate 24 moves while in contact with the inclined surface 41 of the moving plate 40 when the inner plate 10 and the outer plate 20 are overlapped and installed. The movement of the plate 40 is inhibited, and although not shown in the drawing, an elastic body such as a spring that applies a resilient force is configured between the upper end of the moving plate 40 and the inner plate 10 in the drawing to make the moving plate 40 smooth. You can also try to descend.

As such, in the embodiment of the application of the moving plate 40 of the present invention, as shown in FIG. 10 , the contact point of the restraining plate 24 and the inclined surface 41 is changed according to the relative movement of the inner plate 10 and the outer plate 20 , and the moving plate (40) is moved, the relative movement of the inner plate 10 and the outer plate 20 are spaced apart from each other, that is, in the same drawing, the inner plate 10 moves to the left, the outer plate 20 moves to the right, or the inner plate ( 10) and the outer plate 20 move to the left and right at the same time, respectively, while the restraining plate 24 moves in a direction away from the moving plate 40, the moving plate 40 moves in a descending direction in the same figure. In contrast, relative movement in which the inner plate 10 and the outer plate 20 are close to each other, that is, in the same drawing, the inner plate 10 moves to the right, the outer plate 20 moves to the left, or the inner plate 10 and When the outer plate 20 moves to the right and left at the same time, respectively, the moving plate 40 moves in an upward direction in the drawing while the restraining plate 24 moves in a direction close to the moving plate 40 side.

In addition, as in FIGS. 9 and 10 , the moving plate 40 is completely separated between the guide walls 12 and is lost in the process of installing the crack gauge of the present invention or in the process of lowering the moving plate 40 . In order to prevent this, a stopper 19 that is a protrusion may be installed on the surface of the inner plate 10 under the moving plate 40 .

As such, it can be confirmed by amplifying the relative movement distance of the inner plate 10 and the outer plate 20 according to the crack variation through the moving plate 40 active structure of the present invention, which is the inclination angle of the moving plate 40 inclined surface 41 . That is, it can be achieved by setting the angle θ between the inclined surface 41 and the adjacent guide wall 12 to be less than 45 degrees, and thus it is possible to accurately detect even minute crack fluctuations, which were practically impossible to read with the naked eye in the prior art. .

In addition, as in FIG. 9 , an enlarged chuck 13 is displayed on one guide wall 12 , an indicator 49 is displayed on the surface of the moving plate 40 , and the moving plate 40 from the guide wall 12 . By attaching the see-through plate 45 that suppresses separation to the guide wall 12, by confirming the indication state of the enlarged chuck 13 of the moving plate 40 surface indicator 49 through the see-through plate 45 which is a transparent material , it is possible to detect a change in the position of the moving plate 40 according to the relative movement of the inner plate 10 and the outer plate 20 as a specific numerical value.

10 is to explain the effect of amplifying the crack variation distance by the moving plate 40 described above, and between the inclined surface 41 of the moving plate 40 and the adjacent guide wall 12 in the embodiment shown in the same figure. The angle θ is set to be less than 45 degrees, and the horizontal distance versus the vertical distance in the same drawing of the inclined surface 41 formed by the angle θ between them is h versus v, and when the angle θ is less than 45 degrees , v/h exceeds 1, and v/h can be converted into the ratio of the vertical movement distance of the moving plate 40 to the horizontal movement distance of the restraining plate 24 in the same drawing, so that v/h is It can be said that the amplification ratio of the active movement distance of the moving plate 40 amplifies the relative movement distance of the inner plate 10 and the outer plate 20 .

Therefore, as illustrated in FIG. 10 , when v/h is set to 2, the relative movement distance of the inner plate 10 and the outer plate 20 according to the crack fluctuation is doubled as the movement distance of the moving plate 40 . As expressed, it is possible to secure significantly improved precision compared to the method of reading the position of the leader line 93 on the target mark 92, and when the angle θ is further reduced to increase v/h, the detection precision can be further improved.

10: inner plate
12: guide wall
13: zoom
15: background part
16: display unit
19 : stopper
20: outer plate
24 : Suppression board
25 : Concealment
26: see-through
30: extension
40: moving plate
41: slope
45: sight plate
49: indicator
91: fixing unit
92 : mark
93: leader line

Claims (2)

A part of the tip of the inner plate 10 attached to one side of the cracked part of the structure and a part of the tip of the outer plate 20 attached to the other side of the cracked part overlap each other, and as the crack width fluctuates, the outer plate 20 on the surface of the inner plate 10 ) As a crack gauge in which the overlapping portion is changed while the inner plate 10 and the outer plate 20 move relative to each other in the direction of crack width change in a state in which the rear surfaces are close, a dark background portion 15 is formed on the surface of the inner plate 10 In the background part 15, a plurality of display parts 16, which are bright parts as an object orthogonal to the relative movement direction of the inner plate 10 and the outer plate 20, are formed at equal intervals and spaced apart from each other. In (20), a plurality of concealing units 25, which are dark objects in a direction parallel to the display unit 16, are formed at equal intervals, and a plurality of see-through units 26 formed between the concealing units 25 are spaced at equal intervals. formed, the distance between the display unit 16 and the see-through unit 26 is the same, so that the display unit 16 of the inner plate 10 and the concealing unit 25 of the outer plate 20 are overlapped with the inner plate ( As 10) and the outer plate 20 are moved relative to each other, the display part 16 of the inner plate 10 and the see-through part 26 of the outer plate 20 overlap and the entire display part 16 is exposed at the same time. In
A pair of guide walls 12 orthogonal to the relative movement direction of the inner plate 10 and the outer plate 20 are formed to be spaced apart from each other on the inner plate 10;
Between the guide wall 12, a moving plate 40 having an inclined surface 41 formed on the side of the outer plate 20 is coupled to be able to slide freely in a direction parallel to the guide wall 12, the inclined surface 41 and the angle between the adjacent guide wall 12 is set to less than 45 degrees;
A protruding restraining plate 24 is formed at the front end of the outer plate 20, so that when the inner plate 10 and the outer plate 20 are overlapped and installed, the end of the restraining plate 24 is on the inclined surface 41 of the moving plate 40. inhibiting the movement of the moving plate 40 while in contact;
A multi-slit display type crack gauge, characterized in that the moving plate 40 moves while the contact point between the restraining plate 24 and the inclined surface 41 is changed according to the relative movement of the inner plate 10 and the outer plate 20. delete

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