JP7402270B2 - Metal cylindrical resistance measurement jig, resistance measurement system, resistance measurement method, and plate thickness evaluation method - Google Patents

Description

The present invention relates to a resistance measuring jig, a resistance measuring system, a resistance measuring method, and a plate thickness evaluation method for a metal cylinder.

Metal cylindrical bodies such as assembled steel plate columns and steel pipe columns are low-cost and high-strength structures, so they are used in a variety of infrastructure facilities, such as supports for power transmission and distribution lines, lighting, and signals, and as wireless radio towers. has been done. Metal cylindrical bodies are susceptible to corrosion at the ground level due to the influence of moisture in the ground, so inspections are periodically performed to check whether corrosion has progressed at the ground level. In this inspection, the thickness of the corroded steel plate in the metal cylinder is measured, and if the measured value does not meet standards, the steel plate is replaced. For example, Patent Document 1 discloses a method of irradiating ultrasonic waves to a steel plate assembly column using an ultrasonic flaw detector and evaluating the degree of defects in the steel plate assembly column based on reflected waves from the steel plate assembly column. There is.

Japanese Patent Application Publication No. 2013-160683

In the method of Patent Document 1, it is necessary to remove the rust film over a wide area, and cleaning requires a lot of effort. By cleaning, the thickness of the steel plate decreases, and the metal base material is exposed, which may lead to corrosion. In addition, if the steel plate has irregularities such as pitting corrosion, there is a problem in that the surface of the steel plate cannot be measured with an ultrasonic flaw detector. It is also possible to use a general-purpose ultrasonic thickness gauge, but general-purpose ultrasonic thickness gauges do not take into account the thickness measurement of curved metal cylinders, and corrosion may occur on metal cylinders. Accurate plate thickness measurement is difficult even when there is no

The present invention has been made based on this background, and provides a resistance measuring jig, a resistance measuring system, a resistance measuring method, and a plate thickness evaluation that can easily evaluate the plate thickness even when a metal cylinder is corroded. The purpose is to provide a method.

In order to achieve the above object, the resistance measuring jig according to the present invention includes:
A plate-shaped body that can be deformed to match the shape of the metal cylinder,
a plurality of drill blades extending in a direction intersecting the plate surface direction of the main body, rotatably supported while being arranged in a row in the plate surface direction of the main body, and capable of removing a rust film formed on the metal cylindrical body; and,
Supporting means provided on the upper surface of the main body and rotatably supporting the drill blade;
Equipped with
The drill blade is configured such that a proximal end portion of the drill blade is disposed outside the support means, is connectable to a terminal of a resistance meter, and has conductivity capable of conducting an electric signal.

According to the present invention, it is possible to provide a resistance measurement jig, a resistance measurement system, a resistance measurement method, and a plate thickness evaluation method that can easily evaluate the thickness of a metal cylinder even when the metal cylinder is corroded.

1 is a schematic diagram showing the configuration of a resistance measurement system according to Embodiment 1 of the present invention. 1 is a diagram showing the configuration of a resistance meter according to Embodiment 1 of the present invention. (a) and (b) are a front view and a bottom view, respectively, showing the configuration of a resistance measuring jig according to Embodiment 1 of the present invention. 1 is a side view showing the configuration of a resistance measuring jig according to Embodiment 1 of the present invention. 1 is a block diagram showing a hardware configuration of an arithmetic device according to Embodiment 1 of the present invention. FIG. (a) is a diagram showing an example of a data table of the resistance value storage section, and (b) is a diagram showing an example of the data table of the plate thickness change rate storage section. 1 is a flowchart showing the flow of a plate thickness evaluation method according to Embodiment 1 of the present invention. 1 is a flowchart showing the flow of a resistance measurement method according to Embodiment 1 of the present invention. 3 is a flowchart showing the flow of arithmetic processing according to Embodiment 1 of the present invention. (a), (b), and (c) are a front view, a top view, and a side view, respectively, showing the configuration of a resistance measuring jig according to Embodiment 2 of the present invention. It is a flowchart which shows the flow of the resistance measurement method based on Embodiment 2 of this invention. FIG. 3 is a diagram showing the relationship between the resistance value and temperature of steel materials. 2 is a graph created based on the measurement results of resistance values for each test piece in Example 1. 7 is a graph showing the relationship between the resistance value and the distance from the end in Example 2. FIG. FIG. 7 is a diagram showing measurement points in a steel plate assembly in Example 3. FIG. 7 is a diagram showing the measurement results of the resistance value and the conversion result of the thinning rate for each measurement location in Example 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A resistance measuring jig, a resistance measuring system, a resistance measuring method, and a plate thickness evaluation method according to embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or equivalent parts are given the same reference numerals.

(Embodiment 1)
A resistance measurement jig, a resistance measurement system, a resistance measurement method, and a plate thickness evaluation method according to the first embodiment will be described with reference to FIGS. 1 to 9. Hereinafter, an example will be described in which a resistance measurement system is used to evaluate the thickness of a steel plate assembly column at a location where corrosion has occurred at the ground level.

As shown in FIG. 1, the resistance measurement system 1 includes a resistance meter 2 that measures the resistance of a steel plate assembly column, and a resistance measurement fixture that is attached to the steel plate assembly column and electrically connects the resistance meter 2 and the steel plate assembly column. A tool 3 is provided. The resistance measuring jig 3 is provided with an attachment hole into which the terminal of the resistance meter 2 is inserted, and by inserting the terminal of the resistance meter 2 into the attachment hole of the resistance measuring jig 3, the resistance meter 2 and the resistance measurement are connected. The jig 3 is electrically connected.

As shown in FIG. 2, the resistance meter 2 is a four-terminal resistance meter, and is connected to a main body 21 that includes a constant current power source and a voltmeter, and to the constant current power source of the main body 21, and supplies a constant current to the measurement target. A pair of current source terminals 22 and a pair of voltage detection terminals 23 are connected to the voltmeter of the main body 21 and detect a voltage drop in the object to be measured. In a four-terminal resistance meter, since the input impedance of the voltmeter is high, almost no current flows through the lead wire on the voltage detection terminal side, and the resistance of the measurement target can be measured without being affected by the resistance of the lead wire or contact resistance. The current source terminal 22 and the voltage detection terminal 23 are each formed into a pin shape so that they can be inserted into a mounting hole provided in the resistance measuring jig 3. Hereinafter, when it is not necessary to distinguish between the current source terminal 22 and the voltage detection terminal 23, they will be collectively referred to as the terminal 2A.

Next, the configuration of the resistance measuring jig 3 according to the first embodiment will be described with reference to FIGS. 3 and 4. The resistance measuring jig 3 removes the rust film formed on the surface of the steel plate assembly column while attached to the steel plate assembly column, and connects the contact point on the surface of the steel plate assembly column where the metal base material is exposed to the terminal of the resistance meter 2. This is a jig for electrically connecting 2A.

The resistance measuring jig 3 has a main body 3A that can be deformed according to the shape of the steel plate assembly column, and is arranged in a row with respect to the main body 3A. Four connection units 3B are provided for electrically connecting each terminal 2A to each contact point where the metal base material of the steel plate assembly column is exposed. The reason why each connection unit 3B is arranged in a line is to make it easier to bend the main body 3A in accordance with the curvature of the steel plate assembly column, and to improve the accuracy of resistance measurement by the resistance meter 2.

The main body 3A is made of a rubber plate that can be deformed to match the shape of the steel plate assembly column. Four recesses 3a are formed in the bottom surface of the main body 3A, arranged in a row at equal intervals in the direction of the plate surface. A through hole 3b is formed in the center of the recess 3a from the recess 3a toward the upper surface of the main body 3A, and a pair of through holes 3c are formed at both ends of the recess 3a toward the upper surface of the main body 3A. has been done. Here, the plate surface direction refers to any direction within the plane in which the plate-shaped main body 3A extends.

Each connection unit 3B is arranged at both ends of the recess 3a of the main body 3A in alignment with the through hole 3c, and has a pair of magnets 31 that can be attracted to the steel plate assembly column, and is provided on the upper surface of the main body 3A, and together with each magnet 31, the main body A plate member 32 arranged to sandwich the main body 3A, a frame member 33 provided on the upper surface of the plate member 32, and a frame member 33 rotatably supported by the main body 3A, the plate member 32, and the frame member. A drill blade 34 is disposed to penetrate through the steel plate assembly column 33 and removes a rust film on the surface of the steel plate assembly column, and a rotary knob 35 is provided on the base end side of the drill blade 34 and receives a rotation operation of the drill blade 34 by the user. Be prepared.

Each magnet 31 slightly protrudes from the bottom surface of the main body 3A so as to be attracted to the surface of the steel plate assembly column. Each magnet 31 is, for example, a permanent magnet and is formed into a disk shape. A through hole 31a through which a bolt 31b can be inserted is provided in the center of each magnet 31.

The plate-like member 32 is a plate-like member arranged parallel to each of the recesses 3a. The plate-like member 32 has a through-hole 32a provided at the center through which the drill blade 34 is inserted, and a pair of through-holes 32a arranged on both sides of the through-hole 32a into which the heads of bolts 33d fixed to the frame member 33 are embedded. It includes a through hole 32b and a pair of through holes 32c that are arranged outside the pair of through holes 32b and into which the bolts 31b are inserted.

The plate-like member 32 is fixed to the main body 3A with the pair of magnets 31 sandwiching the main body 3A from above and below. Bolts 31b are inserted into the through holes 31a of the magnet 31, the through holes 3c of the main body 3A, and the through holes 32c of the plate member 32, and nuts 31c are tightened on the bolts 31b.

The through hole 32b includes a large diameter portion that accommodates the head of the bolt 33d, and a small diameter portion through which the shaft of the bolt 33d can be inserted, but through which the head of the bolt 33d cannot be inserted. Since the through hole 32b can completely accommodate the head of the bolt 33d, the head of the bolt 33d does not interfere with the upper surface of the main body 3A even when the plate member 32 and the main body 3A are fixed.

The frame member 33 includes an upper surface, a lower surface, and a pair of side surfaces connected to the upper and lower surfaces, respectively. Through-holes 33a and 33b into which the drill blade 34 is inserted are formed in the upper surface and the lower surface, respectively, and the upper surface, the lower surface and a pair of side surfaces of the frame member 33 define an internal space in which the drill blade 34 is accommodated. is forming. A pair of female screw holes 33c are provided on the bottom side of the lower surface portion of the frame member 33. The frame member 33 is fixed to the plate member 32 by tightening a bolt 33d inserted into the through hole 32b of the plate member 32 into a female screw hole 33c.

The drill blade 34 is a drill that has both conductivity capable of transmitting electric signals and hardness capable of crushing the rust film on the steel plate assembly. The drill blade 34 is preferably a glass drill blade capable of drilling holes in glass, in view of crushing the rust film on the steel plate assembly. The glass drill blade is made of a cemented carbide, for example, an alloy made by mixing and sintering tungsten carbide and cobalt powders. The distance between the drill blades 34 is set at a constant distance from each other, while taking into account the measurement accuracy by the resistance meter 2, the plurality of contacts to which the respective terminals 2A of the resistance meter 2 are electrically connected are arranged in a line on the surface of the steel plate assembly. The interval is set as follows. In order to obtain an average resistance value on a highly uneven corroded steel plate, it is better to increase the distance between the drill blades 34, but if the distance between the drill blades 34 is increased, the measured voltage will become smaller, resulting in measurement errors. becomes larger. According to the results of repeated experiments, the distance between the drill blades 34 is preferably within a range of 20 mm to 30 mm, and more preferably 25 mm.

The rotary knob 35 includes an insertion port 35a formed to match the terminal 2A of the resistance meter 2, and an attachment port 35b formed to match the drill blade 34. The insertion port 35a and the attachment port 35b form one through hole that penetrates from the upper surface to the lower surface. A female threaded hole 35c is formed in the mounting port 35b in a vertical direction. The drill blade 34 is fixed to the rotary knob 35 by attaching the drill blade 34 to the attachment port 35b and tightening a bolt into the female screw hole 35c. When the terminal 2A is inserted into the insertion port 35a with the drill blade 34 attached to the attachment port 35b, the distal end surface of the terminal 2A contacts the base end surface of the drill blade 34, and the terminal 2A is electrically connected to the drill blade 34. Connected.

The resistance measuring jig 3 is provided at the intermediate portion of the drill blade 34 and is arranged between a stopper 36 that restricts the movement of the drill blade 34 in the axial direction, and the top surface of the frame member 33 and the stopper 36. The frame member 33 further includes a coil spring 37 that presses the frame member 33 against the lower surface of the frame member 33. The plate member 32, the frame member 33, the stopper 36, and the coil spring 37 are provided on the upper surface of the main body 3A, and urge the drill blade 34 in the direction in which the drill blade 34 moves forward, and also enable the drill blade 34 to rotate. This is an example of supporting means.

The stopper 36 is a cylindrical member, and includes a through hole into which the drill blade 34 is inserted. The peripheral wall of the stopper 36 is provided with a female screw hole that penetrates in the radial direction of the through hole toward the through hole, and by tightening a bolt into the female screw hole, the stopper 36 is fixed to the intermediate portion of the drill blade 34. . The stopper 36 is disposed in the internal space of the frame member 33 and comes into contact with the lower surface of the frame member 33 to restrict movement of the drill blade 34 toward the main body 3A side.

Further, the stopper 36 is pressed against the lower surface portion of the frame member 33 by the coil spring 37 in a state where no load is applied to the drill blade 34 in the pushing direction. In this state, the drill blade 34 protrudes slightly, for example, about 5 mm, from the bottom surface of the main body 3A. When the drill blade 34 is pushed toward the rotary knob 35, the stopper 36 is urged to return to its original position by the action of the coil spring 37 compressed toward the upper surface of the frame member 33. Therefore, when the resistance measuring jig 3 is attached to the steel plate assembly column, the drill blade 34 that has contacted the surface of the steel plate assembly column is pushed slightly toward the rotary knob 35, and the drill blade 34 is urged toward the surface of the steel plate assembly column. be done. Thereby, the drill blade 34 can be reliably brought into contact with the surface of the steel plate assembly column while the resistance measuring jig 3 is attached to the steel plate assembly column.

Since the resistance measuring jig 3 has the above-described configuration, it can easily create four contacts with exposed metal base material on the surface of the steel plate assembly column, and measure the resistance at the measurement location of the steel plate assembly column. In addition, the resistance value measured by the resistance meter 2 corresponds to the average value of the cross-sectional area at the measurement location of the steel plate assembly column that has an uneven surface. The mechanical strength of steel plates, which depends on the cross-sectional area, can be easily evaluated.
The above is the configuration of the resistance measurement jig 3.

Next, with reference to FIG. 5, the hardware configuration of the arithmetic device 100 according to the first embodiment will be described. Arithmetic device 100 is, for example, a general-purpose computer. The arithmetic device 100 includes an operation section 110, a display section 120, a communication section 130, a storage section 140, and a control section 150. Each part of the arithmetic device 100 is interconnected via an internal bus (not shown).

The operation unit 110 receives a user's instruction and supplies an operation signal corresponding to the accepted operation to the control unit 150. The operation unit 110 includes, for example, a mouse and a keyboard.

The display unit 120 includes a display drive circuit, and displays various images for the user based on data supplied from the control unit 150.

The communication unit 130 is a communication interface through which the computing device 100 communicates with external equipment. The communication unit 130 communicates with external devices via a communication network such as the Internet and input/output terminals, for example. The input/output terminal is, for example, a USB (Universal Serial Bus).

The storage unit 140 includes, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, and a hard disk. The storage unit 140 stores programs executed by the control unit 150 and various data. Furthermore, the storage unit 140 temporarily stores various information and also functions as a work memory for the control unit 150 to execute processing. Furthermore, the storage unit 140 includes a resistance value storage unit 141 and a plate thickness change rate storage unit 142.

As shown in FIG. 6A, the resistance value storage unit 141 stores the resistance value measured by the resistance meter 2 in association with the identification number and measurement position of the steel plate assembly column. The identification number of the steel plate assembly column is a unique number assigned to each steel plate assembly column. The measurement position is expressed, for example, by the axial position (height) z1, z2, . . . of the steel plate assembly column, and the angle r1, r2, . . . around the axis of the steel plate assembly column.

As shown in FIG. 6B, the plate thickness change rate storage unit 142 stores the plate thickness change rate calculated by the calculation device 100 in association with the identification number and measurement position of the steel plate assembly column.

Returning to FIG. 5, the control section 150 includes a processor and controls each section of the arithmetic device 100. The processor is, for example, a CPU (Central Processing Unit). The control unit 150 executes the arithmetic processing shown in FIG. 9 by executing the program stored in the storage unit 140. Functionally, the control section 150 includes an acquisition section 151, an average value calculation section 152, a plate thickness change rate calculation section 153, and an output section 154.

The acquisition unit 151 acquires data regarding the resistance value measured by the resistance meter 2, and stores it in the resistance value storage unit 141 in association with the identification number and measurement position of the steel plate assembly column. Acquisition of data by the acquisition unit 151 includes reading data stored in the storage unit 140.

The average value calculation unit 152 calculates the average value of the resistance values at the healthy location and each corroded location based on the resistance values acquired by the acquisition unit 151.

The plate thickness change rate calculation unit 153 calculates the plate thickness change rate at each corroded location based on the average value of the resistance value at the healthy location and each corroded location calculated by the average value calculation unit 152, and identifies the steel plate assembled column. It is stored in the plate thickness change rate storage unit 142 in association with the number and the measurement position. The plate thickness change rate at a corroded location is calculated by dividing the average value of the resistance value at the corroded location by the average value of the resistance value at the healthy location.

The output unit 154 outputs data on the plate thickness change rate at each corrosion location calculated by the plate thickness change rate calculation unit 153 to the outside. For example, the rate of change in plate thickness at each corrosion location may be displayed on the display unit 120.
The above is the configuration of the arithmetic device 100.

(Plate thickness evaluation method)
Next, with reference to FIG. 7, the flow of the plate thickness evaluation method performed by the user using the resistance measurement system 1 according to the first embodiment will be described.

First, the resistance of a corrosion location where corrosion has occurred on the surface of the steel plate assembly is measured (step S11). Since the corroded part of the steel plate assembly column is located in the soil, dig a hole with a shovel or the like to expose the steel plate assembly column. Corrosion points are selected by visually checking the steel plate assembly once the steel plate assembly column is exposed, and picking out several locations that are likely to have thinning. The resistance measurement is performed, for example, by the method shown in FIG. In on-site resistance measurements, errors are likely to occur due to the influence of the surrounding environment, so it is preferable to measure the resistance at the same location at least five times or more.

Next, the resistance of a healthy area where no corrosion has occurred on the surface of the steel plate assembly is measured (step S12). As the healthy location, any location above ground that is not normally corroded may be selected, or a location in the soil that is not visually observed to be corroded may be selected. The resistance measurement method is the same as in the step S11.

Next, the plate thickness at the corroded area is evaluated by comparing the resistance value of the corroded area measured in the process of step S11 with the resistance value of the healthy area measured in the process of step S12 (step S13). Specifically, the rate of change in plate thickness at the corroded location is calculated by causing the arithmetic device 100 to execute the arithmetic processing shown in FIG. Next, it may be determined whether or not the steel pipe in the steel plate assembly needs to be replaced based on the calculated plate thickness change rate at the corroded location.
The above is the flow of the plate thickness evaluation method.

(Resistance measurement method)
The flow of the resistance measurement method performed by the user using the resistance measurement system 1 according to the first embodiment will be described below with reference to FIG. In the resistance measurement method according to the first embodiment, since the resistance measurement jig 3 is used, one worker can perform resistance measurement even when handling four terminals 2A.

First, the resistance measuring jig 3 is installed at the measurement location of the steel plate assembly column (step S21). The main body of the resistance measuring jig 3 is brought into contact with the surface of the steel plate assembly column so as to stretch the entire body. When the resistance measuring jig 3 comes into contact with the surface of the steel plate assembly column, the magnet 31 attracts the resistance measurement jig 3 to the surface of the steel plate assembly column. Note that the portions of the steel plate assembly where the steel pipes overlap (the portions where they come into contact with each other) are not selected as measurement locations because the accuracy of measuring the resistance value decreases. If possible, it is preferable to select a location 100 mm or more away from the end of the steel pipe as the measurement location.

Next, a contact point is created on the surface of the steel plate assembly column by removing the rust film at the measurement point to the extent necessary for resistance measurement and exposing the internal metal base material at a pinpoint (step S22). Specifically, the rotation knob 35 is lightly rotated while holding down the main body 3A. When rotating the rotary knob 35, there is no need to apply any particular force, and it is sufficient to turn the rotary knob 35 slowly about 10 times.

Next, the terminal 2A is inserted into the attachment port 35b of the rotary knob 35 of the resistance measuring jig 3, and the contact point where the metal base material of the steel plate assembly column is exposed is electrically connected to the terminal 2A of the resistance meter 2. (Step S23).

Next, the resistance at the measurement location is measured using the resistance meter 2 (step S24). Specifically, the measurement value of the resistance meter 2 is read when the measurement value output by the resistance meter 2 becomes stable. If the measured value is not output or the measured value is unstable due to poor contact of the terminal, the rotary knob 35 may be turned again to improve the contact state between the contact point of the steel plate assembly column and the terminal of the resistance meter 2.

Next, the resistance measuring jig 3 is removed from the steel plate assembly column (step S25), and all steps are completed.
The above is the flow of the resistance measurement method.

(arithmetic processing)
Next, with reference to FIG. 9, the flow of arithmetic processing executed by the arithmetic device 100 according to the first embodiment will be described. The calculation process starts when the calculation device 100 receives an instruction from the user after measuring the resistance of the steel plate assembled column using the resistance meter 2.

First, the acquisition unit 151 acquires data regarding the resistance value measured by the resistance meter 2, and stores it in the resistance value storage unit 141 in association with the identification number and measurement position of the steel plate assembly column (step S31).

Next, the average value calculation unit 152 calculates the average value of the resistance values at the healthy location and each corroded location based on the resistance values acquired by the acquisition unit 151 (step S32).

Next, the plate thickness change rate calculation unit 153 calculates the plate thickness change rate at each corroded location based on the average value of the resistance values at the healthy location and each corroded location calculated by the average value calculation unit 152, and calculates the plate thickness change rate at each corroded location. It is stored in the board thickness change rate storage unit 142 in association with the identification number and measurement position of the assembly column (step S33). The plate thickness change rate at a corroded location is calculated by dividing the average value of the resistance value at the corroded location by the average value of the resistance value at the healthy location.

Next, the output unit 154 causes the display unit 120 to display data on the plate thickness change rate at each corrosion location calculated by the plate thickness change rate calculation unit 153 (step S34), and ends the process.
The above is the flow of the calculation process.

As described above, the resistance measuring jig 3 according to the first embodiment includes a plate-shaped main body 3A that can be deformed according to the shape of a steel plate assembly, and extends in a direction perpendicular to the plate surface direction of the main body 3A. A plurality of drill blades 34 are rotatably supported in a line in a row in the direction of the plate surface of the main body 3A, and are capable of removing a rust film formed on the steel plate assembly. Therefore, by pinpointing the rust film on the steel plate assembly with the simple operation of rotating each drill blade 34, the multiple contacts that are electrically connected to the terminal 2A of the resistance meter 2 can be lined up. It can be created at regular intervals and can measure the resistance in the steel plate of the steel plate assembled column.

(Embodiment 2)
A resistance measurement jig, a resistance measurement system, a resistance measurement method, and a plate thickness evaluation method according to the second embodiment will be described with reference to FIGS. 10 and 11. In the first embodiment, after removing the rust film using the resistance measuring jig 3, the terminal 2A of the resistance meter 2 was electrically connected to the resistance measuring jig 3, but in the second embodiment, the resistance measuring jig 3 The difference is that after removing the rust film using the measuring jig 4, the terminal 2A of the resistance meter 2 is electrically connected directly to the steel plate assembly column. The resistance measuring jig 4 according to the second embodiment is useful when the resistance measuring jig 3 according to the first embodiment cannot remove a rust film. The following will mainly explain the differences between the two.

With reference to FIG. 10, the configuration of the resistance measuring jig 4 according to the second embodiment will be described. The resistance measuring jig 4 is a jig that guides the drill blade of an electric drill that removes the rust film on the surface of the steel plate assembly column and creates a contact point for the terminal 2A of the resistance meter 2 while being attached to the steel plate assembly column. . The drill blade of the electric drill is preferably a glass drill blade, similar to the drill blade 34 of the resistance measurement jig 3.

The resistance measuring jig 4 includes a main body 4A that can be deformed to match the shape of the steel plate assembly column, and four guide units 4B that are arranged in a line with the main body 4A and each receives a drill blade of an electric drill. . The reason why each guide unit 4B is arranged in a row is to make it easier to bend the main body 4A in accordance with the curvature of the steel plate assembly column, and to improve the accuracy of resistance measurement by the resistance meter 2.

The main body 4A is made of a rubber plate that can be deformed to match the shape of the steel plate assembly column. Four through holes 4a are formed in the main body 4A, which are arranged in a line at equal intervals in the direction of the plate surface and penetrate from the lower surface toward the upper surface. Furthermore, a pair of through holes 4b are formed on both sides of the through hole 4a, each penetrating from the lower surface toward the upper surface.

Each guide unit 4B is provided on the bottom surface of the main body 4A, is arranged in accordance with the through hole 4b, and has a pair of magnets 41 that can be attracted to the steel plate assembly column. The guide member 42 is arranged to sandwich the main body 4A and guides the drill blade of the electric drill.

Each magnet 41 is formed into, for example, a disk shape. Each magnet 41 protrudes in a direction away from the bottom surface of the main body 4A so as to be attracted to the surface of the steel plate assembly column. A through hole 41a through which a bolt 41b can be inserted is formed in the center of each magnet 41.

The guide member 42 includes a plate member 42a installed on the upper surface of the main body 4A, and a cylindrical sleeve 42b extending from the lower surface of the plate member and accommodated in the through hole 4a of the main body 4A. A guide hole 42c is formed in the center of the guide member 42, into which a drill blade of an electric drill is inserted. The guide hole 42c is formed to narrow from the upper surface to the lower surface. The distance between the center points of adjacent guide holes 42c is set similarly to the distance between the drill blades 34 of the resistance measuring jig 3, and is preferably within the range of 20 mm to 30 mm, and preferably 25 mm. More preferred.

A pair of through holes 42d into which bolts 41b are inserted are formed at both ends of the plate member 42a. The guide member 42 is fixed to the main body 4A with the pair of magnets 41 sandwiching the main body 4A. A bolt 41b is inserted through the through hole 41a of the magnet 41, the through hole 4b of the main body 4A, and the through hole 42d of the guide member 42, and a nut 41c is tightened on the bolt 41b.
The above is the configuration of the resistance measurement jig 4.

(Resistance measurement method)
Hereinafter, with reference to FIG. 11, a flow of a resistance measurement method performed by a user using the resistance measurement system 1 according to the second embodiment will be described. This method requires at least two workers because it is necessary to manually hold the four terminals of the measuring meter 2 and bring them into contact with the contacts made on the steel plate assembly column.

First, the resistance measuring jig 4 is installed at the measurement location of the steel plate assembly column (step S41). The entire main body 4A of the resistance measuring jig 4 is stretched and brought into contact with the surface of the steel plate assembly column. When the resistance measuring jig 4 comes into contact with the surface of the steel plate assembly column, it is attracted to the surface of the steel plate assembly column by the magnet 41.

Next, an electric drill is set in the guide hole 42c, and the rust film on the steel plate assembly column is removed with the electric drill, thereby creating a contact point with the terminal 2A of the resistance meter 2 on the steel plate assembly column (step S42). At the contact points of steel plate assembly columns, it is necessary to expose the metal base material. To confirm that the metal base material is exposed, use a penlight to illuminate the cut area and visually observe whether the reflected light produces a glossy appearance.

Next, the resistance measuring jig 4 is removed from the steel plate assembly column (step S43).

Next, the contacts of the steel plate assembly column and the terminals of the resistance meter are electrically connected (step S44). Since the contact point of the steel plate assembly column is slightly recessed compared to the surrounding area, when the pin-shaped terminal 2A of the resistance meter 2 is applied to the contact point, the position can be confirmed by feeling with the hand.

Next, the resistance at the measurement location is measured (step S45). Specifically, the measured value output by the resistance meter 2 is read when it becomes stable.
The above is the flow of the resistance measurement method.

The resistance measuring jig 4 according to the second embodiment includes a main body 4A that can be deformed according to the shape of the steel plate assembly column, and a main body 4A that is arranged in a line with respect to the main body 4A so as to penetrate through the main body 4A. and a plurality of guide members 42 that guide a drill blade of an electric drill capable of removing a rust film formed on the steel plate assembly column toward the steel plate assembly column. Therefore, even if it is difficult to remove the rust film with the resistance measuring jig 4, it is possible to repeatedly create multiple contacts with the metal base material exposed on the surface of the steel plate assembly column using an electric drill at the same interval, so that the steel plate assembly The resistance of the pillar to be measured can be easily measured, and the resistance values of each measurement target can be compared with each other.

The present invention is not limited to the embodiments described above, and modifications described below are also possible.

(Modified example)
In the embodiment described above, a case has been described in which the resistance measurement system 1 is used to evaluate the plate thickness at a corrosion location that has occurred in a steel plate assembly column, but the present invention is not limited to this. For example, the resistance measurement system 1 may be used to evaluate the plate thickness at a worn portion of the steel plate assembly column.

In the embodiment described above, a four-terminal resistance meter is used as the resistance meter 2, but the present invention is not limited to this. The resistance meter 2 may be any resistance meter as long as it can accurately measure the resistance of the steel plate. The number of connection units 3B and guide units 4B in the resistance measuring jigs 3 and 4 may be set according to the number of terminals of the resistance meter 2.

In the embodiment described above, the main bodies 3A and 4A are both formed of rubber plates, but the present invention is not limited to this. The main bodies 3A and 4A only need to be deformable in accordance with the curvature of the steel plate assembly column, and may be constructed by, for example, arranging four plate members in a row and connecting adjacent plate members to each other so as to be bendable with a hinge. Good too.

In the embodiment described above, the magnets 31 and 41, the plate member 32, and the guide member 42 are configured to be removable from the main bodies 3A and 4A, but the present invention is not limited to this. For example, the magnets 31 and 41, the plate member 32, and the guide member 42 may be fixed so that they cannot be removed from the main bodies 3A and 4A.

In the first embodiment, the magnet 31 is attached to the recess 3a of the main body 3A, but the present invention is not limited to this. For example, the recess 3a may be omitted in the main body 3A.

In the embodiment described above, the magnets 31 and 41 are permanent magnets, but the present invention is not limited to this. For example, as the magnets 31 and 41, electromagnets that generate magnetic force when energized may be used.

In the first embodiment described above, the plate-like member 32 and the frame member 33 are separate members and are configured to be removable from each other, but the present invention is not limited to this. For example, the plate-like member 32 and the frame member 33 may be integrally configured.

In the first embodiment described above, the drill blade 34 extends in a direction perpendicular to the plate surface direction of the main body 3A, but the present invention is not limited to this. The drill blade 34 only needs to extend in a direction intersecting the plate surface direction of the main body 3A, and for example, the drill blade 34 may be tilted with respect to a direction perpendicular to the main body 3A.

In the first embodiment described above, the drill blade 34 has conductivity, but the present invention is not limited to this. For example, if the resistance measuring jig 3 is only used to create a contact point on the surface of a steel plate assembly column, the drill blade 34 may be non-conductive.

In the first embodiment described above, the terminal 2A of the resistance meter 2 is inserted into the insertion port 35a so that the distal end surface of the terminal 2A is brought into contact with the proximal end surface of the drill blade 34, but the present invention is not limited to this. . For example, the base end of the drill blade 34 may be exposed from the base end surface of the rotary knob 35, and the base end of the drill blade 34 may be held between an alligator clip provided on the terminal 2A of the resistance meter 2. Alternatively, the rotary knob 35 may be omitted and the terminal 2A may be directly connected to the drill blade 34.

In the first embodiment, the coil spring 37 is disposed between the upper surface of the frame member 33 and the stopper 36, but the present invention is not limited to this. If it is determined that there is no need to press the drill blade 34 against the surface of the steel plate assembly column in consideration of the state of the rust film, the stopper 36 and the coil spring 37 may be omitted.

In the embodiment described above, the resistance value outputted by the resistance meter 2 is used as it is, but the present invention is not limited to this. The resistance meter 2 measures the outside temperature using an attached temperature sensor, corrects the measured resistance value to a resistance value at a preset temperature, and outputs the corrected resistance value. Therefore, if the temperature on the surface of the steel plate assembly column differs from the outside temperature, an error may occur in the resistance value.

In such a case, for example, based on a graph showing the relationship between the temperature of the steel material and the theoretical value of the resistance value as shown in FIG. Create a table in advance. Then, when measuring the resistance, the temperature of the surface of the steel plate assembly column is measured with a thermometer, and the resistance value is corrected according to the measured value of the temperature of the steel plate assembly column surface with reference to the conversion table. At this time, a non-contact type thermometer may be used to measure the temperature of the surface of the steel plate assembly column so as not to disturb the temperature field on the surface of the steel plate assembly column.

In the embodiment described above, the plate thickness change rate at the corroded location is measured based on the resistance value measured by the resistance meter 2, but the present invention is not limited to this. For example, the plate thickness at the corroded location may be calculated based on the resistance value measured by the resistance meter 2. Specifically, a master curve (relational expression) indicating the relationship between the resistance value of the steel plate and the thickness of the steel plate is stored in the storage unit 140 of the calculation device 100, and the control unit 150 of the calculation device 100 is stored in the storage unit 140. It is preferable to provide a plate thickness calculation unit that calculates the thickness of the steel plate from the resistance value of the steel plate based on the master curve stored in the master curve. The master curve may be generated in advance by repeating resistance measurements on test pieces whose thicknesses are known for each material.

In the embodiment described above, various data are stored in the storage unit 140 of the arithmetic device 100, but the present invention is not limited thereto. For example, all or part of various data may be stored in an external control device or computer via a communication network.

In the above embodiment, the arithmetic device 100 operates based on the programs stored in the storage unit 140, but the present invention is not limited thereto. For example, a functional configuration realized by a program may be realized by hardware.

In the above embodiment, the arithmetic device 100 is, for example, a general-purpose computer, but the present invention is not limited to this. For example, the arithmetic device 100 may be realized by a computer provided on a cloud.

In the embodiment described above, the processing executed by the arithmetic device 100 is realized by a device having the above-described physical configuration executing a program stored in the storage unit 140. The program may be realized as a storage medium on which the program is recorded.

In addition, the program for executing the above-mentioned processing operations can be read by a computer such as a flexible disk, CD-ROM (Compact Disk Read-Only Memory), DVD (Digital Versatile Disk), or MO (Magneto-Optical Disk). By storing and distributing the program in a non-transitory recording medium and installing the program on a computer, an apparatus that executes the above processing operations may be configured.

The above-mentioned embodiments are illustrative, and the present invention is not limited thereto, and various embodiments are possible without departing from the spirit of the invention described in the claims. The components described in each embodiment and modification example can be freely combined. Furthermore, inventions equivalent to the inventions described in the claims are also included in the present invention.

The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to these examples.

(Example 1)
In Example 1, a test piece with a known thickness was used to verify whether there was a correlation between the thickness of the test piece and the resistance value. First, five types of test pieces with different plate thicknesses were created. Each test piece was cut out from a commercially available carbon steel with a size of 400 mm x 400 mm, and had no corrosion. The plate thicknesses of each test piece were 1.5 mm, 1.8 mm, 2.3 mm, 2.6 mm, and 3.0 mm, respectively. Terminal 2A of resistance meter 2 was connected to these test pieces using either resistance measuring jig 3 or 4, and the resistance value was measured five times for each test piece. As resistance meter 2, HIOKI RM3584 was used.

As a result, when the resistance values were plotted on a graph as shown in FIG. 13, it was found that the thickness of the test piece and the resistance value were in an inversely proportional relationship. The correlation coefficient is 0.9997. Note that the standard deviation of the resistance values measured five times for each test piece was 0.4 or less, which was sufficiently small for all test pieces, and the results of the resistance value measurement are considered to be valid.

(Example 2)
Next, we verified the influence of the location where the steel plates overlap when measuring the resistance of the steel plates of the steel plate assembly column using a test piece with a known thickness. This is because it is thought that where the steel plates overlap, the spread of the electric lines of force is suppressed at the ends of the steel plates, resulting in a higher current density, and as a result, the apparent resistance value increases. In this verification, a test piece with a thickness of 2.3 mm was used, and the resistance was repeatedly measured by shifting the measurement position at intervals of 10 mm from the end of the test piece. Other conditions were the same as in Example 1.

As a result, as shown in FIG. 14, it was found that the influence of the current density at the end of the test piece can be ignored when the distance is 100 mm or more from the end of the test piece. Therefore, it can be understood that it is desirable to create a contact point in which the metal base material is exposed at a location 100 mm or more away from the end of the steel plate.

(Example 3)
In Example 3, it was verified whether plate thickness could be evaluated based on resistance value using a steel plate assembly in actual equipment. First, a steel plate assembly from an actual facility was sampled, and the resistance was measured at three measurement locations of low corrosion level, medium corrosion level, and high corrosion level shown in FIG. 15, and the plate thickness at each measurement location was evaluated. A low corrosion level is a location where corrosion cannot be visually confirmed, a medium corrosion level is a location where some corrosion can be visually confirmed, and a high corrosion level is a location where corrosion has clearly progressed compared to the medium corrosion level. The resistance measurements were carried out six times each under the same conditions as in Example 1.

As a result, resistance values were obtained as shown in FIG. The thinning rate (plate thickness change rate) for small corrosion levels is 0%, and the thinning rate for medium and large corrosion levels is the ratio of the resistance value for medium and large corrosion levels to the resistance value for small corrosion levels. When expressed, as shown in FIG. 16, the thinning rates at medium and high corrosion levels were 26.0% and 35.8%, respectively. This thinning rate corresponds well to the visually confirmed corrosion status of steel plate assemblies in actual equipment, and it was confirmed that the plate thickness can be evaluated based on the resistance value even in steel plate assemblies in actual equipment.

1 Resistance measurement system 2 Resistance meter 3, 4 Resistance measurement jig 3A, 4A Main body 31 Magnet 34 Drill blade 35 Rotary knob 35a Insertion port 35b Mounting port 42 Guide member 42c Guide hole

Claims (8)

A plate-shaped body that can be deformed to match the shape of the metal cylinder,
a plurality of drill blades extending in a direction intersecting the plate surface direction of the main body, rotatably supported while being arranged in a row in the plate surface direction of the main body, and capable of removing a rust film formed on the metal cylindrical body; and,
Supporting means provided on the upper surface of the main body and rotatably supporting the drill blade;
Equipped with
The drill blade is configured such that a base end of the drill blade is disposed outside the support means, is connectable to a terminal of a resistance meter, and has conductivity capable of conducting an electric signal.
Resistance measurement jig. The support means urges the drill blade in a direction in which the drill blade advances.
The resistance measuring jig according to claim 1 . A plate-shaped body that can be deformed to match the shape of the metal cylinder,
a plurality of drill blades extending in a direction intersecting the plate surface direction of the main body, rotatably supported while being arranged in a row in the plate surface direction of the main body, and capable of removing a rust film formed on the metal cylindrical body; and,
Equipped with
The main body is formed with a plurality of through holes through which each drill blade is passed,
A pair of magnets that attract the surface of the metal cylinder are provided on the bottom of the main body on both sides of each through hole, respectively.
Resistance measurement jig. A plate-shaped body that can be deformed to match the shape of the metal cylinder,
a plurality of drill blades extending in a direction intersecting the plate surface direction of the main body, rotatably supported while being arranged in a row in the plate surface direction of the main body, and capable of removing a rust film formed on the metal cylindrical body; and,
Equipped with
A rotary knob that can be rotated by the user is provided at the base end of the drill blade,
The rotary knob includes an insertion port provided on the base end side into which a terminal of a resistance meter can be inserted, and an attachment port provided on the distal end side to which the base end portion of the drill blade is attached,
The insertion port and the attachment port are formed such that when the terminal is inserted into the insertion port, the terminal comes into contact with a base end portion of the drill blade attached to the attachment port .
Resistance measurement jig. A plate-shaped body that can be deformed to match the shape of the metal cylinder,
A plurality of units are provided on the main body arranged in a line in the direction of the plate surface of the main body, and guide a drill blade of an electric drill capable of removing a rust film formed on the metal cylinder toward the surface of the metal cylinder. a guide member;
A resistance measuring jig comprising:
A guide hole is formed in the guide member, penetrating from the upper surface to the lower surface thereof, into which a drill blade of the electric drill can be inserted.
Resistance measurement jig. The resistance measuring jig according to any one of claims 1 to 5 ,
a resistance meter comprising a plurality of terminals electrically connected to each contact point of the metal cylinder from which a rust film has been removed using the resistance measuring jig;
Resistance measurement system with. A step of mounting the resistance measuring jig according to any one of claims 1 to 5 on the metal cylinder;
creating a plurality of contacts on the metal cylinder by removing a rust film on the metal cylinder using the resistance measuring jig;
a step of electrically connecting each terminal of a resistance meter to each contact made on the metal cylinder;
Measuring the resistance of the metal cylinder with the resistance meter;
Resistance measurement methods including. Measuring the resistance of the corroded portion and the healthy portion of the metal cylinder using the resistance measuring jig according to any one of claims 1 to 5 ;
determining the plate thickness of the corroded area by comparing the resistance value of the sound area and the resistance value of the corroded area;
Plate thickness evaluation method including

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