JPH088404Y2 - Crack gauge - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is intended for measuring the length and propagation speed of a crack by adhering to a place where a crack is predicted to occur or a place where a crack has already occurred. It relates to the crack gauge used.

[Conventional technology]

A crack gauge is a grid that is made of a resistance film and a gauge tab are formed on the surface of a gauge base like a general strain gauge, but a large number of grids electrically arranged in parallel are formed as the crack progresses. The resistance value changes in accordance with the progress of cracks as the strands to be cut are sequentially cut.

FIG. 2 is a plan view showing a conventional example of such a crack gauge.

In the drawing, 1 is a gauge base, 2, 2, ... Are grids made of resistive films 3, which are arranged in parallel to each other, and the length gradually increases from one end (lower end in the drawing) side to the other end side. Thus, the gauge tabs 3, 3 provided at both ends are connected in parallel. still,
Although only a part of the grids 2, 2 is illustrated, the grids 2, 2 are arranged in the entire area of the inverted trapezoid formed between the gauge tabs 3, 3. Reference numerals 4 and 4 are lead wires connected to the gauge tabs 3 and 3.

Reference numeral 5 is a trigger, which is composed of a resistance film provided on the crack generation side of the grids 2, 2, ... (The side where the grids 2, 2 are short). Reference numerals 6 and 6 are trigger tabs provided at both ends of the trigger 5. The trigger 5 and the trigger tabs 6 and 6 are provided to cause the measuring instrument to start the measurement operation by the crack gauge.

That is, in order to measure the length of propagation of cracks and the propagation velocity of cracks by the grids 2, 2, ..., Standby is often required as a prerequisite. Therefore, if the standby is performed when the trigger 5 is cut by a crack, the crack measurement operation by the grids 2, 2, ... Can be automatically started. This is the reason why the trigger 5 and the trigger tabs 6, 6 are provided.

[Problems to be solved by the device]

By the way, the conventional crack gauge shown in FIG. 2 has a problem that the trigger 5 is only on the side where the crack is generated, and the timing for ending the crack detection is unclear.

That is, when the crack progresses and the number of remaining grids 2, 2, ... Remains low, the resistance between the gauge tabs 3, 3 increases considerably, but even if the number of cut grid wires differs by 1 or 2, the resistance value Since there is little change, it is difficult to judge whether or not all grids have been cut. Therefore, there is a problem that the end time of crack detection becomes unclear.

Further, in the conventional crack gauge shown in FIG. 2, since the trigger tabs 6, 6 are provided on the crack generation side of the gauge tabs 3, 3, the edge of the gauge base 1 on the crack generation side and the grid 2 are There is a problem that the distance l is large, and therefore the crack propagation velocity and the like cannot be measured for the initial crack by the distance l.

The present invention is to solve these problems, and a first object thereof is to provide a crack gauge capable of detecting not only the crack detection start time but also the crack detection end time. An object of the present invention is to provide a crack gauge capable of reliably measuring an initial crack by shortening the distance between the edge of the gauge base on the side where cracking occurs and the gauge grid.

[Means for solving the problem]

In order to achieve the first object, the crack gauge of claim 1 is characterized in that triggers and trigger tabs are provided on both sides of the grid and gauge tabs on the crack generation side and the final grid side.

In order to achieve the second object, a crack gauge according to a second aspect is characterized in that, in the crack gauge according to the first aspect, the gauge tab is provided with a notch, and the trigger tab is located at the notch.

[Action]

According to the crack gauge of the first aspect, since the triggers are provided on both sides of the gauge grid on the side of the crack generation and the side of the final grid, it is possible to detect the crack detection end time as well as the crack detection end time.

According to the crack gauge of the second aspect, since the trigger tab is located in the notch provided in the gauge tab, the grid can be brought closer to the edge of the gauge base by the width of the trigger tab. Therefore, the initial grid length at which measurement becomes impossible can be shortened.

〔Example〕

 Hereinafter, the present invention will be described with reference to the illustrated embodiments.

FIG. 1 is a plan view showing an embodiment of the present invention.

In the figure, 1 is a gauge base. 2,2, ... are grids formed on the gauge base 1, 3,3 are gauge tabs, 3a, 3a, 3a, 3a are notches formed in the corners of the gauge tabs 3, 3, 4, 4 , ... are lead wires connected to the gauge tabs 3, 3, respectively.

5 is a trigger on the crack generation side formed on the crack generation side of the gauge grids 2, 2, ..., 6 and 6 are trigger tabs formed on both ends of the trigger 5, and the cutouts 3a, 3a of the gauge tabs 3 and 3 above. It is located inside. In this way, the trigger tabs 6,6 are located in the notches 3a, 3a of the gauge tabs 3,3 because the trigger tabs 6,6 are present on the grids 2,2 ,. The distance l'with the edge is not increased.

Therefore, the distance l'of the present crack gauge is smaller than that of the conventional crack gauge shown in FIG. Specifically, the distance l, which was 3 mm in the past, can be set to l '= 0.04 mm, and the initial crack can be measured.

7 is a final grid side trigger provided on the final grid side of the grids 2, 2, ..., 8 and 8 are trigger tabs provided at both ends of the final grid side trigger 7, and are gauge tabs.
It is located in the notch 3a, 3a of 3,3 .... In this way, the trigger 7 is also set on the final grid side of grids 2, 2, ....
The reason why the trigger tabs 8 and 8 are provided is that the crack detection end time can be detected. Reference numerals 9 and 9 are connected to the trigger tabs 6 and 6, and 10 and 10 are lead wires connected to the trigger tabs 8 and 8.

Thus, according to this crack gauge, not only the trigger 5 and the trigger tabs 6 and 6 are provided on the crack generation side of the gauge grids 2, 2, ..., but also the trigger 7 and the trigger tabs 8 on the final grid side. Since 8 are provided, it is possible to accurately detect not only the crack detection start time but also the crack detection end time.

When the crack generating side trigger 5 and the final grid side trigger 7 are broken, for example, along with the progress of a crack generated in the structure, the trigger signal can be taken out as an electric signal that changes from H level to L level. By providing the detection circuit, the operation (measurement) start and the operation (measurement) end of the measuring instrument can be controlled. That is, automation of the measurement operation or unmanned measurement can be realized, which in turn saves the electricity cost of the measuring device,
Or it will lead to the saving of recording paper.

Further, the trigger tabs 6 and 8 are, as described above,
The area occupied by the gauge tabs 3, 3, ... Is cut out so as to be arranged reasonably, so that the surface area is large and the lead wires 9,
It is 9 and 10 and 10 connection work. There is an advantage that so-called pole attachment can be performed easily, and therefore the measurement preparation time can be greatly shortened.

Also, connect the trigger tabs 6, 6 to the cutouts 3a, 3 of the gauge tabs 3, 3.
Since it is located at a, the trigger tabs 6 and 6 are on the gauge grid.
The distance l between 2, 2, ... And the edge of the gauge base 1 on the side where the crack is generated is no longer present, and the distance l can be shortened. Therefore, it is possible to measure the propagation velocity and the like in the initial stage of the crack.

[Effect of device]

As is clear from the above description, according to the strain gauge of claim 1, not only the crack detection start time but also the crack detection end time can be detected.

Further, according to the strain gauge of the second aspect, the distance between the gauge grid and the edge of the gauge base on the side where the crack is generated can be shortened, so that the initial portion of the crack can be measured.

[Brief description of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG. 2 is a plan view showing a conventional example. 1 ... Gauge base, 2 ... Grid, 3 ... Gauge tab, 3a ... Gauge tab notch, 4, 9, 10 ... Lead wire,
5,7 …… Trigger, 6,8 …… Trigger tab.

Claims (2)

[Scope of utility model registration request] 1. A crack gauge comprising a grid and a gauge tab, wherein a trigger and a trigger tab are provided on both sides of the gauge tab on the crack generation side and the final grid side. 2. The crack according to claim 1, wherein the gauge tab is provided with a notch, and the trigger tab is arranged in the notch of the gauge tab to reduce the distance between the base edge and the gauge grid as much as possible. gauge.