Method and apparatus for inspecting seams in impermeable sheets

Abstract

To save labor by easily grasping a length of an inspection section of a seam in inspecting the seam of liquid impermeable sheets.SOLUTION: At a seam 3 between edges 2e of liquid-impermeable sheets 2 installed adjacent to each other on an installation object 1, both longitudinal ends of a linear gap portion 3Rc to be inspected are closed, and inspection gas is introduced into the linear gap portion 3Rc until it reaches a set pressure, and then, the seam 3 is inspected for quality based on the pressure in the linear gap portion 3Rc. A flowmeter 18 measures a cumulative introduction flow rate of the inspection gas into the linear gap portion 3Rc during the introduction. A processing unit 30 calculates a length of the linear gap portion 3Rc based on a width of the linear gap portion 3Rc and the cumulative introduction flow rate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and apparatus for inspecting the quality of a seam of a liquid-impermeable sheet, and particularly relates to a seam inspection method and apparatus suitable for liquid-impermeable sheets installed in large-area civil engineering structures and building structures such as tunnels and industrial waste disposal sites.

Background Art

[0002] For example, it is known to lay liquid-impermeable sheets such as waterproof sheets and water-shielding sheets on installation targets such as tunnel excavation surfaces and industrial waste disposal sites to prevent groundwater from leaking out or sewage from permeating into the ground (see Patent Document 1, etc.). Normally, since this type of installation target has a larger area than the width of a single liquid-impermeable sheet, a plurality of liquid-impermeable sheets are arranged side by side to cover the installation target. The edges of adjacent liquid-impermeable sheets are overlapped and welded by a welding machine to form a seam. Inside the seam, a linear gap is defined along the longitudinal direction thereof (see Patent Documents 2 and 3, etc.).

[0003] When inspecting the quality of a seam, a section to be inspected on the seam is selected, both ends of the linear gap in that section (hereinafter referred to as the "linear gap portion") are closed with a clamp or the like, and then an inspection gas such as compressed air at a set pressure is introduced into the linear gap portion to monitor the pressure change in the linear gap portion. If the welded state of the seam is good, the linear gap portion is maintained in a pressurized state. If the welded state of the seam is defective, air leaks from the defective portion, and the pressure in the linear gap portion decreases. Thereby, the quality of the seam can be determined (see Patent Documents 2 and 3, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] In the inspection of the quality of the aforementioned joints, the test is conducted to determine whether a certain percentage (e.g., within 80%) of the set pressure is maintained for a certain period of time (e.g., 2 minutes), taking into account factors such as the elongation of the impermeable sheet when compressed air is introduced and leakage from around the needle used for introducing compressed air. On the other hand, the degree of pressure drop depends on the volume and, consequently, the length of the linear gap in the inspection section. Currently, the inspection report includes the pressure measurement results of the joint, the length of the linear gap measured by a tape measure or visual estimation, and a photograph of the joint. However, measurement with a tape measure is cumbersome and time-consuming. In some cases, the joint is not straight but curved, making a tape measure unsuitable. Needless to say, visual measurement is inaccurate. In view of these circumstances, the present invention aims to reduce labor in seam inspection of impermeable sheets such as protective sheets and waterproof sheets by making it easy to determine the length of the inspection section of the seam. [Means for solving the problem]

[0006] To solve the aforementioned problems, the present invention provides a method for inspecting the quality of a joint formed by overlapping the edges of impermeable sheets installed adjacent to each other on an object to be installed and welding them together to define a linear gap between them, by closing both ends in the longitudinal direction of the linear gap portion to be inspected, introducing an inspection gas into the closed linear gap portion until it reaches a set pressure, and then inspecting the quality of the joint based on the pressure in the linear gap portion, A step of measuring the cumulative flow rate of the inspection gas introduced into the linear gap portion during the introduction process, A step of calculating the length of the linear gap portion based on the width of the linear gap portion and the cumulative introduction flow rate. It is characterized by having the following features. This method allows for the calculation of the length of the linear gap, i.e., the inspection section, without the need to measure it with a tape measure or estimate it by eye, thereby reducing the burden on workers.

[0007] Preferably, the process further includes a step of detecting the temperature of the impermeable sheet, the inspection gas, or the surrounding area, and the calculation is performed based on the width, the set pressure, the cumulative introduction flow rate, and the detected temperature. By applying Boyle's Law and Charles's Law to the set pressure, integrated inlet flow rate, and detected temperature, the volume of the linear gap can be determined. From this volume and the width, the length of the linear gap can be determined.

[0008] The present invention relates to a device that inspects the quality of a joint formed by welding together the edges of two impermeable sheets, which are installed adjacent to each other on an object, so that a linear gap is defined between them. The device involves introducing an inspection gas into the linear gap portion, which is closed at both ends in the longitudinal direction, until it reaches a set pressure, and then inspecting the quality of the joint based on the pressure in the linear gap portion. A flow rate measuring means for measuring the cumulative flow rate of the inspection gas introduced into the linear gap portion during the introduction, A length calculation unit calculates the length of the linear gap portion based on the width of the linear gap portion and the cumulative introduction flow rate. It is characterized by having the following features.

[0009] Preferably, the system further includes a thermometer, and the length calculation unit performs the calculation based on the width, the set pressure, the integrated introduction flow rate, and the temperature detected by the thermometer. The thermometer may detect the temperature of the impermeable sheet, the temperature of the test gas, or the ambient temperature or ambient temperature.

[0010] Preferably, the flow rate measuring means includes a mass flow meter. This allows the volume of the linear gap portion to be obtained by directly using the integrated inlet flow rate obtained by the flow rate measuring means or by multiplying it by a predetermined calibration coefficient, and the length of the linear gap portion can be calculated without temperature detection with a thermometer or without taking the set pressure into calculations. [Effects of the Invention]

[0011] According to the present invention, in the inspection of seams of an impermeable sheet, the length of the inspection section of the seam can be easily determined, thereby saving labor. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is an explanatory diagram showing a seam inspection device according to the first embodiment of the present invention in a state where it is inspecting the quality of seams in an impermeable sheet installed at an industrial waste disposal site, which is an example of an installation target. [Figure 2] Figure 2(a) is a cross-sectional view along the line IIa-IIa in Figure 1, showing the inspection section of the joint before the introduction of the inspection gas. Figure 2(b) is a cross-sectional view showing the inspection section of the joint with the inspection gas introduced. [Figure 3] Figure 3 is a block diagram showing the configuration of the processing unit of the seam inspection device. [Figure 4] Figure 4 is an explanatory diagram showing a seam inspection device according to the second embodiment of the present invention in a state where it is inspecting the quality of seams in an impermeable sheet installed at an industrial waste disposal site, which is an example of an installation target. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment (Figures 1-3)> As shown in Figure 1, multiple impermeable sheets 2 (waterproof sheets) are laid out in the industrial waste disposal site 1 (civil engineering structure) where the sheets are to be installed. The edges 2e of adjacent impermeable sheets 2 are overlapped vertically and welded together, forming a joint 3 that extends along the edge 2e.

[0014] As shown in Figure 1 and Figure 2(a), two rows of welding lines 3a are formed at the seam 3. These welding lines 3a are formed by two rows of clamping rollers 4a of the welding machine 4 indicated by imaginary lines in Figure 1. A linear gap 3c is defined by the edge portions of the upper and lower liquid-impermeable sheets 2 between these welding lines 3a. The linear gap 3c extends linearly along the seam 3.

[0015] A part of the seam 3 of the liquid-impermeable sheet 2 is selected as an inspection section 3R, and the quality of the welding work of the seam 3 is inspected by the seam inspection device 10. As shown in Figure 1, the seam inspection device 10 includes a housing 11 (device main body), an inspection gas passage 20, and a processing unit 30. The inspection gas passage 20 includes a supply pipe 21, an internal pipe 22, and an inspection gas introduction pipe 23. Preferably, the housing 11 and thus the seam inspection device 10 have a weight and size that allow easy manual carrying.

[0016] The supply pipe 21 is provided with a compressed air pump 12, an on-off valve 13, a regulator 14 (pressure regulating valve), and a flow rate regulating valve 15 in sequence from the upstream side. The compressed air pump 12 at the upstream end may be an electric type or a hydraulically driven type, and may also be a manually operated hand pump or foot pump. The on-off valve 13 is a manual on-off type, but may be an electromagnetic valve capable of automatic opening and closing. The regulator 14 adjusts the secondary pressure of the compressed air (inspection gas) from the compressed air pump 12 to a set pressure.

[0017] The internal pipe 22 is accommodated in the housing 11. The upstream end of the internal pipe 22 communicates with the downstream end of the supply pipe 21 via the upstream connection port 24. The downstream end of the internal pipe 22 communicates with the inspection gas introduction pipe 23 via the downstream connection port 25. The inspection gas introduction pipe 23 extends from the housing 11 to the seam 3 of the liquid-impermeable sheet 2. A needle-shaped nozzle 26 is provided at the tip of the inspection gas introduction pipe 23.

[0018] The enclosure 11 houses a filter 16, a pressure gauge 17, a flow meter 18, and a printed circuit board 40 (signal processing circuit module). The filter 16, pressure gauge 17, and flow meter 18 are arranged in this order from the upstream side of the internal piping 22 and interposed in the internal piping 22. The flow meter 18 is a volumetric flow meter.

[0019] The printed circuit board 40 includes a detection signal input unit 41, a signal conversion unit 42, an output unit 43, and a GPS module 44. Detection signal lines from the pressure gauge 17 and the flow meter 18 are connected to the detection signal input unit 41, respectively. Furthermore, a detection signal line from the thermometer 19 is connected to the detection signal input unit 41. The thermometer 19 is configured, for example, as a thermocouple. The thermometer 19 is located outside the housing 11, for example, near the seam inspection area of ​​the impermeable sheet 2, but it may also be located on the inspection gas passage 20 or installed in the housing 11.

[0020] The signal conversion unit 42 converts the analog detection signal input to the detection signal input unit 41 into a digital signal. The output unit 43 outputs the digitally converted detection signal via wired or wireless connection.

[0021] The processing unit 30 is comprised of a personal computer (hereinafter referred to as "PC"), preferably a portable PC. Examples of portable PCs include notebook PCs, smartphones, and tablets. More preferably, the processing unit 30 is comprised of a smartphone.

[0022] As shown in Figure 3, the processing unit 30 includes a CPU 31, a communication unit 32, and a storage unit 33. The storage unit 33 stores a quality determination program 34 and a length calculation program 35, and is also provided with a seam quality information storage area 36. The quality determination program 34 causes the CPU 31 of the processing unit 30 to perform quality determination processing on the seam 3. When the quality determination program 34 is executed, the CPU 31 functions as a quality determination unit 31a.

[0023] The CPU 31 of the processing unit 30 executes a process to calculate the length of the inspection section 3R of the joint 3 using the length calculation program 35. When the length calculation program 35 is executed, the CPU 31 functions as the length calculation unit 31b.

[0024] The invariants used in the calculation are pre-stored in the memory unit 33. Examples of invariants include the width W of the linear gap 3c (hereinafter referred to as "linear gap portion 3Rc") in the inspection section 3R, and the set pressure P of the regulator 14. As shown in Figure 2(a), the width W of the linear gap portion 3Rc referred to here is the width of the linear gap portion 3Rc in a flattened state without gas pressure introduced inside, and is equal to the width of the linear gap 3c, and is determined by the spacing d4 (Figure 1) between the two rows of clamping rollers 4a of the welding machine 4. Alternatively, instead of the width W, a width correlation value (cross-sectional area S, diameter D, radius r, etc.) described later may be stored in the memory unit 33.

[0025] As shown in Figure 3, the acquired seam quality information is stored in the seam quality information storage area 36. The seam quality information includes the quality judgment result of the seam 3, as well as the length of the inspection section 3R of the seam 3.

[0026] The joint inspection by the joint inspection device 10 is performed as follows. As shown in Figure 1, a section 3R to be inspected in the joint 3 is selected, and both ends of the longitudinal direction of that section 3R are clamped from both the front and back sides by clamps 5. This closes both ends of the longitudinal direction of the linear gap portion 3Rc (closing process). Preferably, the housing 11 of the joint inspection device 10 is installed near the inspection section 3R.

[0027] Next, the needle-shaped nozzle 26 is inserted into the upper impermeable sheet 2 in section 3R, and the tip of the needle-shaped nozzle 26 is positioned to face the closed linear gap portion 3Rc. Next, the on / off valve 13 is opened to activate the compressed air pump 12. As a result, compressed air (inspection gas) from the compressed air pump 12 is pressure-regulated by the regulator 14 to reach the set pressure, and then introduced into the linear gap portion 3Rc through the inspection gas introduction pipe 23 via the internal piping 22 (introduction process). As shown in Figure 2(b), this deforms the cross-section of the inspection section 3R of the joint 3, and thus the linear gap portion 3Rc, into a circular shape.

[0028] At this time, the flow meter 18 detects the instantaneous flow rate of compressed air at regular time intervals, or measures the cumulative flow rate (flow rate measurement process). The detection signal from the flow meter 18, indicating the instantaneous flow rate or cumulative flow rate, is input to the detection signal input unit 41 of the printed circuit board 40, digitally converted by the signal conversion unit 42, and then transmitted from the output unit 43 to the processing unit 30.

[0029] When the processing unit 30 receives a signal detecting instantaneous flow rate, it calculates the cumulative flow rate introduced into the linear gap portion 3Rc during the introduction process by integrating the detected flow rate. In this case, the flow meter 18 and the processing unit 30 constitute a flow rate measuring means. If the flow meter 18 is capable of measuring the cumulative flow rate of compressed air introduced during the introduction process, the flow meter 18 can constitute a flow rate measuring means on its own.

[0030] The introduction of compressed air increases the internal pressure of the linear gap portion 3Rc. When the internal pressure reaches the set pressure of the regulator 14, the on / off valve 13 is closed. This completes the introduction process.

[0031] Next, the pressure in the linear gap portion 3Rc is detected by the pressure gauge 17. Preferably, pressure detection is performed for several minutes after the completion of the introduction process. The detection signal (detected pressure) from the pressure gauge 17 is input to the detection signal input section 41 of the printed circuit board 40, digitally converted by the signal conversion section 42, and then transmitted from the output section 43 to the processing section 30.

[0032] The quality determination unit 31a of the processing unit 30 determines the quality of the joint based on the detected pressure. Specifically, it determines whether the detected pressure does not fall below a threshold (e.g., 80% of the set pressure) until a predetermined time (e.g., 2 minutes) has elapsed from the end of the introduction process. If the welding state of the joint 3 in the inspection section 3R is good, the detected pressure, i.e., the internal pressure of the linear gap portion 3Rc, is maintained at, for example, 80% or more of the set pressure. If the welding state of the joint 3 is poor, air leaks from the poor location, and the internal pressure of the linear gap portion 3Rc falls below 80% of the set pressure. This allows for the determination of the quality of the joint. The detected pressure and judgment results are stored in the inspection data storage area 36 of the storage unit 33 as the main information for determining whether the joint is good or bad.

[0033] Furthermore, the temperature of the impermeable sheet 2 is detected by the thermometer 19. Preferably, the temperature of the inspection section 3R or its vicinity is detected. Alternatively, the temperature of compressed air (inspection gas) or the ambient temperature (air temperature) may be detected. A detection signal indicating the detected temperature T is input from the thermometer 19 to the detection signal input unit 41, where it is digitally converted by the signal conversion unit 42 and then transmitted from the output unit 43 to the processing unit 30.

[0034] The length calculation unit 31b of the processing unit 30 calculates the length L of the linear gap portion 3Rc based on the set pressure P, the cumulative introduction flow rate V, the detected temperature T, and the width W of the linear gap portion 3Rc. Specifically, by applying Boyle's Law and Charles's Law to the set pressure P, the cumulative introduction flow rate V, and the detected temperature T, the cumulative introduction flow rate V0 can be determined assuming that air (inspection gas) is introduced into the linear gap portion 3Rc under constant conditions (Equation 1). The constant conditions are, for example, standard conditions where P0 = 1 atmosphere and T0 = 20°C or 0°C, and the cumulative introduction flow rate V0 obtained by Equation 1 corresponds to the volume of the linear gap portion 3Rc. V0=f(P,P0,T,T0)·V (Formula 1) In Equation 1, the first term on the right-hand side is a function based on Boyle's Law and Charles's Law, which includes P, P0, T, and T0 as variables or constants.

[0035] As shown in Figure 2(b), the volume V0 of the linear gap portion 3Rc is given by S = W when the linear gap portion 3Rc has a circular cross-section, i.e., when the cross-sectional area S is given by W 2 This is the volume of the linear gap portion 3Rc when / π. Therefore, the length L of the linear gap portion 3Rc can be determined by equation 2 or equation 3. L = π·V0 / W 2 (Formula 2) L=V0 / S (formula 3)

[0036] The cross-sectional area S is a width correlation value that correlates with the width W. In other words, by directly determining the length L based on the width correlation value (Equation 3), it is also possible to effectively determine the length L based on the width W (Equation 2). Other width correlation values ​​besides the cross-sectional area S include the diameter D (=2W / π) and radius r (=W / π) when the linear gap portion 3Rc is made into a circular cross-section. When calculating the length L, a correction may be made to account for the expansion and contraction of the sheet material due to changes in temperature T.

[0037] The data of the length L of the linear gap portion 3Rc, i.e., the inspection section 3R, calculated in this manner, is stored in the data storage area 36 of the storage unit 33 as additional or reference information for the joint quality information, along with the detection pressure and quality judgment result of the main information.

[0038] More preferably, the joint quality information includes location information of inspection section 3R, inspection date and time, etc. Location information is measured by GPS module 44, but the built-in GPS function of processing unit 30 may also be used. An image showing the location of inspection section 3R on a map representing the industrial waste disposal site 1 to be installed may be displayed on the display. In this case, it is preferable to pre-associate the location information on the map with the actual location information measured by GPS at least two points.

[0039] The processing unit 30 can output information on the quality of the seams in the form of an inspection report or similar. The inspection report includes not only the result of the joint's quality assessment but also the length L of the inspection section 3R, allowing for an assessment of the validity of the quality assessment result.

[0040] The joint inspection device 10 can automatically calculate the length L of the inspection section 3R in parallel with the joint quality inspection, eliminating the need for workers to separately measure the length L of the inspection section 3R with a tape measure or visually, thus saving labor. This reduces the burden on workers. Even if the inspection section 3R is curved, the length L can be easily calculated. This provides greater reliability than visual measurement.

[0041] Next, other embodiments of the present invention will be described. In the following embodiments, components that overlap with those described above are denoted by the same reference numerals in the drawings and their descriptions are omitted. <Second Embodiment (Figure 4)> As shown in Figure 4, in the joint inspection device 10B of the second embodiment, a mass flow meter 18B is used as the flow meter for the flow rate measuring means. The joint inspection device 10B is not equipped with a thermometer 19 (Figure 1).

[0042] The mass flow meter 18B detects the mass flow rate (kg / sec) of compressed air (test gas). Since the mass flow rate shows the same value even when the pressure and temperature change, it effectively converts to a volumetric flow rate (m³) under constant conditions such as standard conditions. 3 This is equivalent to ( / sec). In other words, the detection signal from the mass flow meter 18B is output to the processing unit 30 as a detection signal that indicates the volumetric flow rate under constant conditions such as standard conditions.

[0043] Therefore, the measured value of the cumulative inlet flow rate obtained through the compressed gas (test gas) introduction process can represent the volume V0 of the linear gap portion 3Rc under constant conditions such as standard conditions, either directly or by multiplying it by a predetermined calibration coefficient. Consequently, the length L of the linear gap portion 3Rc can be easily calculated without reading the set pressure P or detecting the temperature (see Equations 1 to 3).

[0044] The present invention is not limited to the embodiments described above, and various modifications can be made without departing from its spirit. For example, the installation of the impermeable sheet is not limited to industrial waste disposal sites, but may also be limited to riverbeds, reservoirs, tunnels, and other civil engineering structures, and may even be limited to building structures such as rooftops. The impermeable sheet is not limited to a waterproof sheet; it may also be a waterproof sheet installed on the surrounding surface of a tunnel, etc. [Industrial applicability]

[0045] This invention can be applied, for example, to the installation and construction of waterproofing sheets in industrial waste disposal sites and waterproofing sheets in tunnels. [Explanation of Symbols]

[0046] 1. Industrial waste disposal sites (target sites) 2. Waterproof sheet (impermeable sheet) 2e edge 3rd joint 3a Two-row welding line 3c Linear gap Part of joint 3 (inspection section) 3Rc linear gap portion 10,10B Joint inspection device 11. Enclosure (main unit of the device) 12. Compressed air pump (pressure source) 13. On / off valve 14. Regulator (Pressure Relief Valve) 17. Pressure gauge 18. Volumetric flow meter (flow rate measuring means) 18B Mass flowmeter (flow rate measurement means) 19 Thermometer 20 Inspection gas passage 23 Inspection gas introduction pipe 26 Needle-shaped nozzle 30. Personal Computer (Processing Unit) 31 CPU 31a Quality determination unit 31b Length calculation section 32 Communications Department 33 Storage section 34. Pass / Fail Judgment Program 35 Length Calculation Program 36. Area for storing information on the quality of seams 40 Printed circuit boards (signal processing circuit modules) 41 Detection signal input section 42 Signal conversion section 43 Output section 44 GPS modules

Claims

1. In a method for inspecting the quality of a joint formed by overlapping the edges of impermeable sheets installed adjacent to each other on an installation target and welding them together to define a linear gap between them, the ends of the linear gap portion to be inspected in the longitudinal direction are closed, an inspection gas is introduced into the closed linear gap portion until it reaches a set pressure, and then the quality of the joint is inspected based on the pressure in the linear gap portion, A step of measuring the cumulative flow rate of the inspection gas introduced into the linear gap portion during the introduction process, A step of calculating the length of the linear gap portion based on the width of the linear gap portion and the cumulative introduction flow rate. A method for inspecting seams of an impermeable sheet, characterized by comprising the following features.

2. The process further includes detecting the temperature of the impermeable sheet, the inspection gas, or the surrounding area. The joint inspection method according to claim 1, wherein the calculation is performed based on the width, the set pressure, the cumulative inlet flow rate, and the detected temperature.

3. In a device for inspecting the quality of a joint formed by overlapping the edges of impermeable sheets installed adjacent to each other on an installation target and welding them together to define a linear gap between them, after introducing an inspection gas into the linear gap portion where both ends in the longitudinal direction are closed until a set pressure is reached, the quality of the joint is determined based on the pressure in the linear gap portion. A flow rate measuring means for measuring the cumulative flow rate of the inspection gas introduced into the linear gap portion during the introduction, A length calculation unit that calculates the length of the linear gap portion based on the width of the linear gap portion and the cumulative introduction flow rate. A seam inspection device for impermeable sheets, characterized by being equipped with the following features.

4. The system further includes a thermometer for detecting the temperature of the impermeable sheet, the inspection gas, or the surrounding area. The joint inspection device according to claim 3, wherein the length calculation unit performs the calculation based on the width, the set pressure, the cumulative introduction flow rate, and the temperature detected by the thermometer.

5. The joint inspection device according to claim 3, wherein the flow rate measuring means includes a mass flow meter.

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