CLEARANCE MEASURING METHOD, CLEARANCE MEASURING DEVICE, MEASURING METHOD FOR THREADED JOINT, MEASURING SYSTEM FOR THREADED JOINT, MEASURING TERMINAL, MANUFACTURING METHOD FOR THREADED JOINT, AND QUALITY CONTROL METHOD FOR THREADED JOINT

Abstract

In order to efficiently confirm joining of threaded joints on pipes, the present invention provides a clearance measuring method, for a pair of threaded joints having a male joint and a female joint corresponding to the male joint, for measuring the clearance between the thread of the male joint and the thread of the female joint. The clearance measuring method includes: a joining completed state setting step for setting a joining completed state in which joining of the male joint and the female joint is completed, on the basis of data on thread shapes of the male joint and the female joint; a clearance measuring step for measuring, in the joining completed state, the clearance between the thread of the male joint and the thread of the female joint corresponding to the thread of the male joint; and a rotated state setting step for setting a state in which rotation is made by a predetermined angle in such a direction as to enjoining the joining, if the joining of the male joint and the female joint is not an unjoined state after the clearance measuring step. The steps from the clearance measuring step to the rotated state setting step are repeatedly executed until the joining is unjoined.

Description

[Technical field]

[0001] The present invention relates to a clearance measurement method, a clearance measurement device, a measurement method for a threaded joint, a measurement system for a threaded joint, a measurement terminal, a manufacturing method for a threaded joint, and a quality control method for a threaded joint in a pipe joint structure for joining pipes. [Background technology]

[0002] Conventionally, pipe structures used for the foundations of structures and to prevent landslides can require lengths of several tens of meters depending on the construction conditions. This tendency is particularly pronounced for steel pipes made of steel. When transporting these pipe structures to the construction site, traffic restrictions mean that long pipes cannot be transported. For this reason, they are transported in transportable lengths of several meters at a time, and are joined at the construction site during construction (including pouring).

[0003] A threaded joint is used as a method for joining pipe structures at the construction site, such as the threaded joint disclosed in Patent Document 1. The threaded joint is attached to each end of the pipes to be joined, and is rotated at the construction site to join the pipes and construct the pipe structure.

[0004] Generally, threaded joints are pre-attached to one pipe at the factory, and the female joint to the other pipe, before being shipped to the site. There are several manufacturing procedures, but the male and female joints are often manufactured as a set. After manufacturing, these joints may be attached to the end of a long pipe depending on the intended use. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-311028 Summary of the Invention [Problem to be solved by the invention]

[0006] Whether a threaded joint can be joined or not is determined by the corresponding thread shapes of the male joint and the mating female joint, so the joint is usually checked before use. However, when the threaded joint has a large diameter of 700 mm or more, when the pipe to which the threaded joint is connected is long, such as 5 m or more, or when the threaded joint or the connected pipe is made of heavy metal such as steel, checking the joint becomes difficult. In this case, there are problems such as a significant amount of effort required for checking the joint, damage to the joint itself, and concerns about ensuring safety.

[0007] In particular, in the case of a threaded joint, there may be a location where the clearance (also called play or gap) between the threads of the male joint and the threads of the female joint is insufficient between the joining start position when the male joint and the female joint are disengaged (including the state immediately before the male joint is screwed into the female joint) and the joining completion position when the joining of the male joint and the female joint is completed. If the clearance between the threads of the male joint and the threads of the female joint becomes insufficient, there is a possibility that the joining process of the joint will be interrupted. Therefore, there has been a demand for a technology that can more easily determine whether a thread shape of a threaded joint is joinable or not before use in the field, regardless of the state of the threaded joint or the connected pipe.

[0008] The present invention has been made in consideration of the above, and an object of the present invention is to provide a clearance measurement method, a clearance measurement device, a measurement method for a threaded joint, a measurement system for a threaded joint, a measurement terminal, a manufacturing method for a threaded joint, and a quality control method for a threaded joint, which enable connection confirmation in a threaded joint to be performed more easily regardless of the condition of the threaded joint or the condition of a connected pipe. [Means for solving the problem]

[0009] (1) In order to solve the above-mentioned problems and achieve the above-mentioned object, a clearance measurement method according to one aspect of the present invention is a clearance measurement method for measuring a clearance between a thread of a male joint and a thread of a female joint for a set of a threaded joint having a male joint and a female joint corresponding to the male joint, the clearance measurement method comprising: a joining completion state setting step of setting a joining completion state in which joining of the male joint and the female joint is completed based on data of the thread shapes of the male joint and the female joint, respectively; a clearance measurement step of measuring a clearance between the thread of the male joint and the thread of the female joint corresponding to the thread of the male joint in the joining completion state; and a rotational state setting step of setting a state in which the male joint and the female joint are rotated a predetermined angle in a direction to release the joint if the joint between the male joint and the female joint is not in a disengaged state after the clearance measurement step, and the clearance measurement step to the rotational state setting step are repeatedly performed until the joint is disengaged.

[0010] (2) A clearance measurement method according to one embodiment of the present invention, in the invention described in (1) above, includes at least one of a step of determining pass / fail for the set of threaded joints based on the clearance measured in the clearance measurement step and a predetermined criterion, and an interference information providing step of providing information of an interference point to a point determined to be an interference point based on the clearance measured in the clearance measurement step and a predetermined criterion.

[0011] (3) A method for measuring a threaded joint according to one embodiment of the present invention includes a shape measurement process for measuring the thread shape of a male joint and the thread shape of a female joint corresponding to the male joint for a set of threaded joints, and a clearance measurement process for measuring a clearance for each set of threaded joints by the clearance measurement method of the above-described invention based on data of the thread shape measured in the shape measurement process.

[0012] (4) A manufacturing method for a threaded joint according to the present invention is a manufacturing method for a threaded joint for manufacturing a set of a threaded joint having a male joint and a female joint corresponding to the male joint, and includes a joint manufacturing process for manufacturing a threaded joint, and a joint measurement process for performing the threaded joint measurement method according to the invention described in (3) on the set of threaded joints having a male joint and a female joint produced by the joint manufacturing process.

[0013] (5) A quality control method for a threaded joint according to one embodiment of the present invention is a quality control method for controlling the quality of a set of threaded joints having a male joint and a female joint corresponding to the male joint, the quality control method comprising: a joint manufacturing process for manufacturing the threaded joint; a joint measurement process for measuring the thread shape of the set of threaded joints produced by the joint manufacturing process by the threaded joint measurement method according to the invention described in (3); and a quality control process for controlling the quality of the produced threaded joint using the results obtained from the joint measurement process.

[0014] (6) A clearance measurement device according to one aspect of the present invention is a clearance measurement device that measures the clearance between the threads of a male joint and the threads of a female joint for a set of threaded joints having a male joint and a female joint corresponding to the male joint, and is equipped with a control unit that repeatedly executes the following steps until the joint is disengaged: a joining completion state setting process that sets a joining completion state in which joining of the male joint and the female joint is completed based on data on the thread shapes of the male joint and the female joint, respectively; a clearance measurement process that measures the clearance between the threads of the male joint and the threads of the female joint corresponding to the threads of the male joint in the joining completion state; and, if the joining of the male joint and the female joint is not in a disengaged state after the clearance measurement step, a rotational state setting process that sets a state in which the joint is rotated a predetermined angle in the direction of disengaging the joint.

[0015] (7) In one embodiment of the clearance measurement device of the present invention, in the invention described in (6), the control unit executes a clearance measurement process to measure the clearance between the threads of the male joint and the threads of the female joint corresponding to the threads of the male joint in the joining completion state before the rotational state setting process.

[0016] (8) A clearance measurement device according to one embodiment of the present invention, in the invention described in (6), further includes a communication unit, and the communication unit executes, via the control unit, at least one of an acquisition process of data on the thread shapes of the male joint and the female joint and an output process of information regarding the clearance obtained by the clearance measurement process.

[0017] (9) A threaded joint measurement system according to one embodiment of the present invention comprises a measurement unit configured to be able to measure the thread shape of a male joint and the thread shape of a female joint for a set of threaded joints having a male joint and a female joint corresponding to the male joint, and a clearance measurement device according to the above-mentioned invention that measures a clearance for each set of threaded joints based on data of the thread shape measured by the measurement unit.

[0018] (10) A measurement terminal according to one embodiment of the present invention is configured to be able to measure the clearance between the threads of a male joint and the threads of a female joint for a pair of threaded joints having a male joint and a female joint corresponding to the male joint, and is controlled by a control unit, and comprises: a measurement unit that measures the thread shape of the male joint and the thread shape of the female joint under the control of the control unit, a communication unit that executes at least one of an output process that outputs the measured thread shape as data to a clearance measurement device according to the above invention under the control of the control unit, and an acquisition process that acquires information regarding the clearance for each pair of joints from the clearance measurement device, and an output unit that is capable of outputting the acquired information in a predetermined format under the control of the control unit.

[0019] (11) In one embodiment of the measuring terminal of the present invention, in the invention described in (10), the control unit executes at least one of the following processes: a process for determining pass / fail for the set of threaded joints based on the acquired information regarding the clearance and a predetermined criterion; and an interference information assignment process for assigning information of the interference points to points determined to be interference points based on the acquired information regarding the clearance and a predetermined criterion.

[0020] (12) A measurement system for a threaded joint according to the present invention includes a measurement terminal according to the above invention, and a clearance measurement device according to the above invention that measures a clearance for each pair of the threaded joint based on data of the thread shape measured by the measurement terminal.

[0021] (13) A quality control method for a threaded joint according to one embodiment of the present invention is a quality control method for a threaded joint that controls the quality of a set of threaded joints having a male joint and a female joint corresponding to the male joint, and controls the quality of the set of threaded joints using information regarding the clearance obtained from a clearance measurement process executed by a control unit of the clearance measurement device according to the above invention. Effect of the Invention

[0022] The clearance measurement method, clearance measurement device, measurement method for a threaded joint, measurement system for a threaded joint, measurement terminal, manufacturing method for a threaded joint, and quality control method for a threaded joint of the present invention make it possible to more easily confirm the joining of a threaded joint regardless of the condition of the threaded joint or the connected pipes. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing the start of welding of a threaded joint that is to be measured in a threaded joint measurement system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a state where joining has been completed of a threaded joint that is to be measured in the threaded joint measurement system according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a block diagram showing a threaded joint measurement system according to a first example of an embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing a threaded joint measurement system according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart for explaining the method of measuring a threaded joint according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart illustrating a clearance measurement process according to the first embodiment of the present invention. [Figure 7A] FIG. 7A is a diagram for explaining coordinates of a threaded joint in a clearance measurement method according to an embodiment of the present invention. [Figure 7B] FIG. 7B is a diagram for explaining coordinates of a threaded joint in the clearance measurement method according to an embodiment of the present invention. [Figure 7C] FIG. 7C is a diagram for explaining coordinates of a threaded joint in the clearance measurement method according to an embodiment of the present invention. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing a joining portion of a threaded joint in an embodiment of the present invention. [Figure 9] FIG. 9 is an enlarged cross-sectional view showing an interference portion at a joining portion of a threaded joint in an embodiment of the present invention. [Figure 10] FIG. 10 is a flowchart for explaining a first modified example of the clearance measuring step in the clearance measuring method according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a flowchart for explaining a second modified example of the clearance measuring step in the clearance measuring method according to the first embodiment of the present invention. [Figure 12] FIG. 12 is a flowchart for explaining a threaded joint measurement method according to the second embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart for explaining a threaded joint measurement method according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. Furthermore, the present invention is not limited to the embodiment described below.

[0025] First, a threaded joint that is to be measured by a threaded joint measurement system according to an embodiment of the present invention will be described. Figures 1 and 2 are diagrams showing a joining start state and a joining completion state, respectively, of a threaded joint that is to be measured (measurement target) by the clearance measurement system of this embodiment.

[0026] (Male and female fittings to be measured) As shown in FIG. 1, the threaded joint 10 according to the present embodiment is configured to have a male joint 11 as an inner joint and a female joint 12 as an outer joint. A male thread 13 is formed on the tip side, which is the side where the male joint 11 is inserted and fitted. A female thread 14 is formed on the tip side, which is the side where the female joint 12 is inserted and fitted. The female thread 14 formed on the female joint 12 is formed in a thread shape corresponding to the male thread 13 formed on the male joint 11. As a result, the male joint 11 and the female joint 12 correspond to each other, and are configured so that the male joint 11 can be inserted into the female joint 12 by screwing. The thread shape may be known or unknown. The thread shape may be single-thread or multiple-thread, and in this embodiment, for example, multiple-thread. The thread shape may be a tapered thread or a parallel thread, and in this embodiment, for example, a parallel thread. The material is not particularly limited. Examples include steel, metal materials other than steel, concrete, resin, and a combination of multiple materials. The material of the threaded joint is selected according to the purpose of use and the conditions of the pipes, etc., which will be described later. The present invention is particularly effective in the case of threaded joints that are large in diameter or heavy (long) and therefore difficult to check the joining before shipping from the factory.

[0027] The pipes 15 and 16 each constitute a structure. The pipe 15 constitutes an upper structure. The pipe 16 constitutes a lower structure. As the structure, various structures can be adopted, such as those having a predetermined function when buried in the ground, those used as a part of a structure on the ground, and those transporting gas or liquid by utilizing the internal space of the pipes 15 and 16. Examples of those having a predetermined function when buried in the ground include piles, earth retaining piles, landslide prevention piles, pipe sheet piles, sheet pile walls, and tunnels. Examples of those used as a part of a structure on the ground include columns and beams. Examples of those transporting gas or liquid by utilizing the internal space of the pipes 15 and 16 include oil well pipes, water pipes, and gas pipes. In addition, examples of the pipes 15 and 16 include steel pipes, concrete pipes, resin pipes, and pipes made of a combination of multiple materials. The present invention is particularly effective in the case of steel pipes with threaded joints, in which the pipes 15, 16 are large in diameter, long, or heavy, and therefore it is difficult to check the joints before shipment from the factory.

[0028] In this embodiment, a male fitting 11 having a male thread 13 is fixed to an upper pipe 15. A female fitting 12 having a female thread 14 is fixed to a lower pipe 16. Alternatively, the male fitting 11 may be fixed to the lower pipe 16 and the female fitting 12 may be fixed to the upper pipe 15, in the opposite manner to the above. Also, the male fitting 11 and the female fitting 12 may be used as they are for measurement, without connecting the pipes 15 and 16.

[0029] (First embodiment) Next, a threaded joint measurement system according to a first embodiment of the present invention will be described below. Fig. 3 is a block diagram showing the threaded joint measurement system according to the first embodiment.

[0030] As shown in Fig. 3, the threaded joint measurement system 1 is configured to include a clearance measurement device 20 and a measurement unit 35. Furthermore, the clearance measurement device 20 is connected to a thread processing device 40. The threaded joint measurement system 1 may adopt a configuration including the clearance measurement device 20, the measurement unit 35, and the thread processing device 40. Furthermore, the threaded joint measurement system 1 according to the first embodiment is designed to be used with the clearance measurement device 20 fixed in place, but the measurement unit 35 and the clearance measurement device 20 can be located close to each other or at a large distance from each other.

[0031] (Clearance measuring device) Clearance measurement device 20 includes control unit 21, storage unit 22, and input / output unit 23. It is possible not to provide input / output unit 23. Clearance measurement device 20 can use a known computer, server, notebook computer, mobile terminal, tablet, smartphone, or a virtual device on a network such as the cloud.

[0032] Control unit as control means 2 Specifically, 1 includes a processor having hardware such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an FPGA (Field-Programmable Gate Array), and a main memory unit such as a RAM (Random Access Memory) or a ROM (Read Only Memory) (none of which are shown).

[0033] The storage unit 22 is physically composed of a storage medium selected from a volatile memory such as a RAM, a non-volatile memory such as a ROM, an erasable programmable ROM (EPROM), a hard disk drive (HDD), a solid state drive (SSD), and a removable medium. The removable medium is, for example, a universal serial bus (USB) memory, or a disk recording medium such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray (registered trademark) disc (BD). The storage unit 22 may also be configured using a computer-readable recording medium such as an externally mountable memory card. The storage unit 22 can store an operating system (OS), various programs, various tables, various databases, and the like for executing the operation of the clearance measurement device 20. The various programs include a learning model and a neural network. These various programs can also be recorded on computer-readable recording media such as a hard disk, a flash memory, a CD-ROM, a DVD-ROM, and a flexible disk, and widely distributed.

[0034] The memory unit 22 stores a clearance database 221 and a pipe type database 222. The pipe type database 222 stores various information (pipe type information) related to the male joint 11 and the female joint 12 constituting the threaded joint 10 in a searchable manner as basic information. The pipe type information includes an identification ID of the threaded joint 10, and information such as the dimensions (diameter, thread dimensions, thread pitch, thread height, length, etc.) and specifications of the male joint 11 and the female joint 12. The clearance database 221 stores searchable information related to the clearance between the male thread 13 and the female thread 14 based on the pipe type information, and information on the measurement results related to the clearance between the male thread 13 and the female thread 14 measured by a measuring unit 35 described later (hereinafter, clearance information). In addition to information on the clearance measurement results, the clearance information includes various information related to the clearance, such as flag information as information on the interference location that defines the interference location, and pass / fail (pass / fail) information for the set of threaded joint 10.

[0035] The clearance calculation unit 211 of the control unit 21 is configured to be able to store the thread shapes of the male thread 13 and the female thread 14 measured by the measurement unit 35 as digital data in a clearance database 221 of the storage unit 22. The storage unit 22 may be provided in a housing different from that of the control unit 21, and an external storage device or a virtual storage device such as a cloud on a network can be used.

[0036] In this embodiment, control unit 21 can realize functions that meet a predetermined purpose by loading a program stored in storage unit 22 into a working area of ​​the main storage unit and executing the program to control each component unit, etc. Specifically, control unit 21 can realize the functions of clearance calculation unit 211 and determination unit 212 by executing the program.

[0037] The input / output unit 23 is composed of, for example, a touch panel display, a speaker microphone, a button, a switch, a jog dial, etc. The input / output unit 23 as an output unit is configured to notify the outside of predetermined information by displaying characters, figures, etc. on a screen of a display such as a liquid crystal display, an organic EL display, or a plasma display, or by outputting sound from a speaker, under the control of the control unit 21. The input / output unit 23 includes a printer that outputs predetermined information by printing it on printing paper, etc. The various information stored in the memory unit 22 can be confirmed, for example, on a display of the input / output unit 23 installed in a predetermined office, etc.

[0038] The input / output unit 23 as an input unit is configured by selecting, for example, a keyboard, a touch panel keyboard incorporated inside the input / output unit 23 to detect touch operations on a display panel, a voice input device that enables communication with the outside, a switch, or a jog dial. The input / output unit 23 as an input means can input a clearance measurement value from the input / output unit 23 when the clearance of the thread cross section of the male screw 13 or the female screw 14 is measured visually using the input / output unit 23 as an output means. In addition, although details will be described later, it is also possible to input a flag to be set or turned down based on the presence or absence of interference in the joining of the male screw 13 and the female screw 14 from the input / output unit 23. Specifically, if there is interference between the male screw 13 and the female screw 14, "0" may be input from the input / output unit 23, and if there is no interference, "1" may be input.

[0039] (Measuring section) The measurement unit 35 is composed of at least one device, such as a handheld 3D scanner. As the 3D scanner, for example, a laser irradiation device or an infrared irradiation device can be adopted. Since the handheld 3D scanner needs to be operated while maintaining a focal length (for example, 20 cm to 40 cm) according to the model, it is desirable to secure a space of 50 cm or more around the scanning target.

[0040] From the viewpoint of determining whether the male joint 11 and the female joint 12 can be joined, the measurement accuracy of the measuring unit 35 is preferably about half or less of the desired clearance, specifically, for example, when the clearance is 0.75 mm, about (0.75 / 2=) 0.375 mm or less. The measurement accuracy is set in various ways depending on the size of the screw joint 10 and the thread shapes of the male thread 13 and the female thread 14, and is not limited to these numerical values. In particular, since the screw joint 10 has a three-dimensional shape, blind spots are likely to occur due to uneven parts, so from the viewpoint of operability, a handy measuring instrument such as a handy 3D scanner is desirable. Note that, in the case of a high-precision type of handy 3D scanner, it is usually necessary to attach a marker for shape measurement to the target object every 10 cm or so. In contrast, when the screw joint 10 is large, a markerless handy 3D scanner that does not require the attachment of a marker for shape measurement is desirable from the viewpoint of efficiency.

[0041] Specifically, the sensor constituting the measuring unit 35 can measure the distance from the installation position to the thread surface of the target object, for example, the male screw 13 or the female screw 14, by irradiating and reflecting a predetermined light such as a laser beam. The measuring unit 35 can perform so-called sensing, which measures the distance from the measurement position to the target object surface in association with two-dimensional position information. Sensing includes various measurements performed by the measuring unit 35. As the two-dimensional position information, coordinates (x, y) on the xy plane, coordinates (r, θ) at a distance r and a rotation angle θ, etc. can be used. Based on the distance information corresponding to the two-dimensional position information, the thread shape of the surface of the male screw 13 or the female screw 14 can be measured three-dimensionally.

[0042] In addition, when selecting the equipment for the measuring unit 35, the higher the resolution, the more preferable it is. In this case, the resolution may be sufficient to accurately reproduce the shape of the thread that affects the clearance used to determine whether the male joint 11 and the female joint 12 can be joined. In this embodiment, since local irregularities may not easily occur in the shape of the thread of the male thread 13 or the female thread 14, the resolution may be approximately 1 mm or less, but is not limited to this value. In addition, since the male joint 11 and the female joint 12 are combined on the scanned data to determine whether they can be joined, in the case of an object whose direction is not fixed, it is desirable to ensure the directionality by providing a marker or a mark with a shape that can be recognized by scanning.

[0043] The measurement unit 35 executes an output process to output the measurement values ​​of the thread shape measured by sensing to the clearance measurement device 20. The clearance calculation unit 211 in the control unit 21 of the clearance measurement device 20 stores the acquired measurement values ​​in the clearance database 221 of the storage unit 22.

[0044] (Thread processing device) The thread processing device 40 is a device for an adjustment process for the male threads 13 and the female threads 14 of the threaded joint 10. The thread processing device 40 includes a control unit 41, a memory unit 42, an input / output unit 43, and a thread processing unit 45. The control unit 41, the memory unit 42, and the input / output unit 43 are functionally and physically configured in the same manner as the control unit 21, the memory unit 22, and the input / output unit 23, respectively. The thread processing device 40 is connected to the clearance measurement device 20.

[0045] The control unit 41 can realize a function that meets a predetermined purpose by loading a program stored in the storage unit 42 into a working area of ​​the main storage unit and executing the program to control each component unit through the execution of the program. Specifically, the control unit 41 can realize the function of a machining control unit 411 through the execution of the program. The machining control unit 411 is configured to be able to control the thread machining unit 45.

[0046] The clearance calculation unit 211 of the clearance measurement device 20 reads out the clearance information from the clearance database 221 stored in the storage unit 22, and outputs it to the thread processing device 40. The thread processing device 40, which has acquired the clearance information, stores the acquired clearance information at least temporarily in the storage unit 42. When an instruction to correct an interference portion of the male thread 13 or the female thread 14 is input from an operator or the like through the input / output unit 43, the processing control unit 411 of the control unit 41 controls the thread processing unit 45 to execute a processing process to correct the interference portion based on the acquired clearance information. The thread processing device 40 may be configured integrally with the clearance measurement device 20. Furthermore, the thread processing device 40 can also manufacture the threaded joint 10. The above constitutes a threaded joint measurement system 1 according to a first example of an embodiment.

[0047] (Second embodiment) Next, a threaded joint measurement system according to a second embodiment of the present invention will be described. Fig. 4 is a block diagram showing a threaded joint measurement system according to the second embodiment. As shown in Fig. 4, a threaded joint measurement system 1A includes a clearance measurement device 20 and a measurement terminal 30A that can communicate with each other via a network 2.

[0048] The network 2 is, for example, a public communication network such as the Internet, and is composed of one or a combination of a LAN (Local Area Network), a WAN (Wide Area Network), a telephone communication network such as a mobile phone, a public line, a VPN (Virtual Private Network), a dedicated line, etc. The network 2 is an appropriate combination of wired communication and wireless communication.

[0049] The threaded joint measurement system 1A may further be connected to a thread processing device 40 that is capable of communicating with at least the clearance measurement device 20 via the network 2. The threaded joint measurement system 1A may employ a configuration including the clearance measurement device 20, the measurement terminal 30A, and the thread processing device 40.

[0050] (Clearance measuring device) The clearance measurement device 20A includes a control unit 21, a storage unit 22, an input / output unit 23, and a communication unit 24. The communication unit 24 serving as a communication means is, for example, a LAN (Local Area Network) interface board or a wireless communication circuit for wireless communication. The LAN interface board and the wireless communication circuit are connected to a network 2. The communication unit 24 is connected to the network 2 and communicates with the measurement terminal 30A and the thread machining device 40A. The other configurations are similar to those of the clearance measurement device 20 in the first embodiment.

[0051] (Measuring terminal) The measurement terminal 30A includes a control unit 31, a memory unit 32, an input / output unit 33, a communication unit 34, and a measurement unit 35. The control unit 31, the memory unit 32, the input / output unit 33, and the communication unit 34 have the same physical and functional configurations as the control unit 21, the memory unit 22, the input / output unit 23, and the communication unit 24 described above, respectively.

[0052] Furthermore, the measurement unit 35 in the measurement terminal 30A according to the second embodiment is configured similarly to the measurement unit 35 in the first embodiment. The control unit 31 can realize a function that meets a predetermined purpose by loading a program stored in the storage unit 32 into a working area of ​​the main storage unit and executing the program. Specifically, the control unit 31 can realize the function of a measurement control unit 311 by executing the program. The measurement control unit 311 is configured to be able to control the measurement unit 35.

[0053] (Thread processing device) The thread processing device 40A includes a control unit 41, a memory unit 42, an input / output unit 43, a communication unit 44, and a thread processing unit 45. The communication unit 44, which serves as communication means, is physically and functionally configured in the same manner as the communication unit 24 described above, and is connected to the network 2. The communication unit 44 is connected to the network 2 and communicates with at least the clearance measurement device 20A. The other configurations are the same as those of the thread processing device 40 in the first embodiment. With the above, a threaded joint measurement system 1A according to the second example of the embodiment is configured.

[0054] (First embodiment) (Method of measuring threaded joints) Next, a method for measuring a threaded joint 10 using the threaded joint measurement system 1 according to the first example of an embodiment or the threaded joint measurement system 1A according to the second example configured as described above will be described. Figure 5 is a flowchart showing the method for measuring a threaded joint 10 according to the first embodiment.

[0055] (Threaded joint manufacturing process) As shown in FIG. 5, first, in step ST1, a joint manufacturing process is performed by a thread processing device 40. In step ST1, a forged ring is manufactured by heat treatment. Next, a cast ring is rotated by rotary cutting, and a cutting blade is brought into contact with the cast ring to cut it, thereby processing it into a joint. The movement of the cutting blade can be automatically controlled by the control of the processing control unit 411 according to a predetermined program. Here, as an example, when the thread shape of the joint is a multiple thread thread, cutting is performed little by little at the same place until one part, i.e., one thread, is completed. When one thread is completed, the cutting blade is moved to the next thread. After the thread of the joint is completed, a test joining is actually performed, and the arrival line is marked with an eye mark at the joining completion state that satisfies the structural performance. After that, the joint is released, and an arrow is marked on the start line on the outer circumferential surface of each joint (however, a place without a thread is selected), and an arrow is marked on the male joint 11 that corresponds to the eye mark of the female joint 12 at the time of release. Note that it is not necessary to use a forged ring, and a steel pipe with a plate thickness that can be cut may be used.

[0056] (Pipe connection process) Next, the process proceeds to step ST2, where the pipe connection process is performed. In step ST2, first, the joining of the threaded joint performed in step ST1 is released. Next, either the male joint 11 or the female joint 12, here for example the female joint 12, is attached to a horizontally placed steel pipe. Next, the male joint 11 alone is trial joined to the horizontally placed steel pipe with a female joint. After confirming whether or not the arrival line is reached by this trial joining, the joining is released. Next, the other joint of the male joint 11 and the female joint 12, here for example the male joint 11, is attached to the horizontally placed steel pipe.

[0057] Here, in the case of a combination of a steel screw joint and a steel pipe, this test joint is used to confirm whether the joint can be completed to the joining position while allowing for the effects of thermal deformation due to welding. In the case of a combination of a steel screw joint and a pipe with a steel pipe sheet pile, as an example, the steel connecting joint that connects the steel pipes horizontally is welded, and then the screw joint is welded to the steel pipe. Note that it is also possible not to perform this step ST2.

[0058] (Method of measuring threaded joints) Here, a method for measuring a threaded joint according to this embodiment will be described. This embodiment includes a shape measurement step for measuring the shape of the threaded joint after processing, and a clearance measurement step for a set of threaded joints based on the measured shape of the threaded joint. These shape measurement step and clearance measurement step are performed before the threaded joint 10 is actually used.

[0059] (Shape measurement process) That is, after step ST1 or step ST2 is performed, the process proceeds to step ST3 to perform a shape measurement process. In the shape measurement process, first, the thread shapes of the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 are measured by the measurement unit 35 for one set of threaded joint 10 manufactured in step ST1. The measurement unit 35 outputs or transmits (hereinafter referred to as transmission) measurement data of the measured thread shapes to the clearance measurement device 20. Here, in the shape measurement process of the threaded joint 10, measurement of the thread shape using the measurement unit 35 is performed, for example, by measuring the distance from the measurement unit 35 to the surfaces of the threaded joints (male joint 11, female joint 12).

[0060] In addition, in the shape measurement process of the threaded joint 10, the thread shape can also be measured by photogrammetry using the multiple images acquired by capturing images of the threaded joint (male joint 11, female joint 12) from multiple viewpoints to acquire multiple image data. Specifically, after point cloud data is acquired by a handy 3D scanner constituting the measurement unit 35, the acquired point cloud data is converted into polygons (STL conversion, mesh conversion), and shape measurement and virtual placement are performed by CAD software that performs three-dimensional measurement of the threaded joint 10, which is the target object.

[0061] Here, in order to realize a virtual arrangement, for example, when grasping the shape in detail, it is preferable to make the apex of the screw a data point, etc. In other words, in order to measure the shape of the screw, it is preferable that the apex of the screw is included in the data points of the point cloud data, and more specifically, it is preferable that the apex of the screw is equal to or smaller than the radius of curvature of the apex of the screw, for example, a resolution of about 0.5 mm or less.

[0062] However, in some cases, the shape of the thread is not prone to localized unevenness, and the contact that affects the joinability is surface contact on the thread surface, so the resolution may be about 1 mm. As an example, the accuracy of the data points can be set to half the clearance or less, specifically, for example, when the clearance is 0.75 mm, the accuracy of the data points can be set to 0.375 mm or less, so that the judgment can be made with sufficient accuracy for practical use. By using CAD-based software that performs three-dimensional measurement, the male joint 11 and the female joint 12 are regarded as rigid bodies and the joining judgment is made, so that there is no problem with the pass judgment when there is a clearance. On the other hand, even if there is some interference, it may be possible to fit them together as long as it is within the range of the deformation capacity of the joint as an elastic body.

[0063] As described above, the judgment can be made more accurate by setting a judgment reference value that takes into account the measurement accuracy, ignoring local contact, frictional resistance, amount of elastic deformation, and usage conditions (directivity at the time of joining, such as vertical, horizontal, or diagonal, and outside temperature). The judgment reference value does not necessarily have to be based on 0, and it is also possible to judge whether or not the fitting is possible using, for example, a digital clearance of -0.2 mm (virtual interference amount of 0.2 mm) as the reference. Also, depending on the measurement accuracy, interference may occur even when the clearance is a positive value, so it is desirable to set an appropriate judgment reference. Note that positive and negative clearances depend on the method of sorting, so a negative value may be used to indicate that a clearance exists.

[0064] Furthermore, it is not necessary to measure the entire threaded joint 10, and it is sufficient that the measuring unit 35 measures the outer surface side of the male joint 11 and the inner surface side of the female joint 12. In this case, it is possible to shorten the measurement time and reduce the amount of measurement data. Furthermore, when converting the acquired point cloud data into polygons (STL conversion, mesh conversion), points within a predetermined surface error range (for example, 0.01 mm) can be omitted to reduce the data volume.

[0065] (Clearance measurement process) Next, proceeding to step ST4, a clearance measurement process as part of the clearance measurement method will be described. Fig. 6 is a flowchart showing the clearance measurement method according to the first embodiment. The flowchart shown in Fig. 6 is executed by clearance measurement device 20.

[0066] (Acquisition step) 6, in the clearance measurement method according to the first embodiment, first, in step ST411 as an acquisition step for performing acquisition processing, control unit 21 of clearance measurement device 20 acquires measurement data from measurement unit 35. The measurement data is measurement data relating to the thread shape of the male thread 13 of the male joint 11 and the thread shape of the female thread 14 of the female joint 12 measured by measurement unit 35 in step ST3.

[0067] (Joining completion state setting step) Next, the process proceeds to step ST412, which is a joining completion state setting step for executing a joining completion state setting process, and the clearance calculation unit 211 of the control unit 21 sets a joining completion state in which the male joint 11 is joined to the inside of the female joint 12 based on the acquired measurement data of the thread shapes of the male thread 13 and the female thread 14.

[0068] In the present invention, the "joining completed state" refers to a state in which the entire length of the threaded portion of the male fitting 11 in the pipe axial direction is almost entirely housed inside the female fitting 12, completing the joining, as shown in Figure 2. In other words, it is a state in which the male fitting 11 is screwed into the female fitting 12 and can barely rotate in the direction in which the thread advances. As shown in Figure 2, ideally, the unthreaded portion of the male fitting 11 comes into contact with the tip of the female fitting 12 (this is called shoulder touch).

[0069] The most distinctive feature of the present invention is that the joining completion state is set as the initial position and the measurement of the clearance is started from the joining completion state.

[0070] Usually, when checking a joint with an actual object, the position where the male and female threads join (which is also the start position of the threads in the circumferential direction of the joint) is identified while moving. In the case of a single-start thread, there is only one start position of the threads in the circumferential direction of the joint, and depending on the conditions of the threaded joint as explained above, identifying this position can be very difficult. Also, although there are multiple start positions of the threads in the circumferential direction of the joint, identifying this position is also difficult if it is intended to be used at a specific start position. In particular, when simulating a joint virtually using a computer, etc., there are multiple possible conditions in the circumferential and axial directions for setting the position where the male and female threads join, making it even more difficult to even start screwing in the first place.

[0071] However, the joining completion position where the joining of the male thread and the female thread is completed can be easily set in any environment, including virtual ones. Therefore, in the present invention, the joining completion position is set as the initial position, and the clearance is measured while releasing the joining, thereby simplifying the clearance measurement process and making it possible to measure the clearance more easily regardless of the state of the threaded joint or the connected pipes.

[0072] (Clearance measurement step) Next, the process proceeds to step ST413 as a clearance measurement step, where the clearance calculation unit 211 of the control unit 21 derives the clearance between the male thread 13 and the female thread 14 based on the measurement data of the male thread 13 and the female thread 14 in the joining completed state. The clearance calculation unit 211 derives the clearance at a preset location. In this specification, the clearance is also referred to as a gap or play.

[0073] Here, Fig. 7A, Fig. 7B, and Fig. 7C show a method for creating a coordinate system of measurement positions. That is, as shown in Fig. 7A, a plane is created for creating a cross section of the male thread 13 of the male joint 11 and a cross section along the radial direction of the female thread 14 of the female joint 12, and a cross section line L shown in Fig. 7B is created. Next, two straight lines 1 are created from the cross section line, and an intersection point C is created. Next, as shown in Fig. 7C, a circle (hereinafter, a fit circle) that minimizes the error with the point (designated point) where the curve is designated is created. A coordinate system is created by the center point of this fit circle and multiple intersection points C. Note that the method for creating a coordinate system described with Figs. 7A to 7C is merely an example, and the creation and setting of a coordinate system can be performed by any method.

[0074] Returning to Figure 6, based on the coordinate system created in this way, four locations can be selected as the preset locations, for example, shifted 90° on a circumference with respect to the center of the circle in the cross section (a plane perpendicular to the up-down direction in Figures 1 and 2) of the male joint 11 or female joint 12. Note that the preset locations can also be eight locations, for example, shifted 45° on a circumference with respect to the center of the circle, and are not necessarily limited to a specified position or number.

[0075] In step ST413, the clearance calculation unit 211 generates a cross-sectional view of the thread from the data of the thread shape at four or eight positions set in advance, as described above, and derives the clearance c between the male thread 13 and the female thread 14. In this way, by setting the method of determining the measurement points as shown in Figs. 7A to 7C, the clearance calculation unit 211 can automatically calculate the clearance at the specified positions by a predetermined method. Note that the cross-sectional view of the thread generated by the clearance calculation unit 211 may be output to the input / output unit 23 of the clearance measurement device 20, and an operator may visually determine whether or not there is a clearance, and input the presence or absence of a clearance from the input / output unit 23.

[0076] 8 and 9 show examples of a cross section of the threaded joint 10 converted into digital data, generated by the clearance calculation unit 211 of the clearance measurement device 20 according to the first embodiment. Fig. 8 is a cross section showing an enlarged portion of the digitized threaded joint 10 in which the male thread 13 and female thread 14 are joined without interfering with each other. Fig. 9 is a cross section showing an enlarged portion of the digitized threaded joint 10 in which the male thread 13 and female thread 14 are partially interfering with each other and are not properly joined.

[0077] As shown in FIG. 8, when there is no interference between the threads 13a, 14a and the thread roots 13b, 14b, the male joint 11 and the female joint 12 are joined. Here, for example, the height h of the threads 13a of the male thread 13 that is properly joined is, for example, 5.0 mm. The center of the threads 13a, 14a is the closest point that is half the distance between the corners of the male thread 13. The white points p are measurement points that can ensure sufficient resolution for the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12. The more white points p there are, the more accurate the determination of the center positions of the male thread 13 and the female thread 14 can be.

[0078] The height h of the threads 13a, 14a is the distance between the center of the threads 13a, 14a and the bottom of the stabbing side. The radial clearance c between the threads 13a of the male thread 13 and the thread root 14b of the female thread 14 is, for example, 0.75 mm. The clearance c is the radial component of the line connecting the center of the threads 13a and the center of the thread root 14b of the male joint 11. In other words, the clearance c can be derived from the distance r1 from the radial center of the male joint 11 to the surface circumferentially tangent to the threads 13a of the male joint 11 and the distance r2 from the radial center of the male joint 11 to the thread root 14b of the female joint 12, as c=r2-r1.

[0079] The clearance c is not necessarily limited to the above definition, and various definitions can be set according to whether or not the threaded joint 10 can be joined. For example, as another example of the definition of the clearance c, it is possible to adopt a method of determining the position taking into account the apexes of the threads 13a and 14a. That is, when the apexes to be measured are determined in advance and are connected at an angle, it is also possible to measure the distance corresponding to the radial or axial direction between the connected apexes and set it as the clearance c. In addition, the distance may be measured in the normal direction of each point on the male joint 11 or the line connecting the points, that is, for each mesh, and the distance when the male joint 11 comes into contact with the female joint 12 in the joined state, that is, the shortest distance, may be set as the clearance c. Conversely, the distance may be measured in the direction from the female joint 12 toward the male joint 11.

[0080] On the other hand, as shown in Fig. 9, when interference (interference part E) occurs at least partially between the threads 13a, 14a and the thread roots 13b, 14b due to the positional relationship between the male joint 11 and the female joint 12, the male joint 11 and the female joint 12 are not joined. Here, for example, the height h of the threads 13a of the male thread 13 in an improperly joined state is, for example, 5.0 mm. The radial clearance c between the thread root 14b of the female thread 14 is, for example, -1 mm, that is, there is interference of only 1 mm in the radial direction.

[0081] In the examples of Figs. 8 and 9 described above, the thread pitch P is, for example, 12.5 mm, but is not limited thereto. The thread pitch P is the axial distance from the end of the thread root 13b of a male thread 13 in a certain single thread to the start position of the thread root 13b of the next single thread male thread 13. Alternatively, the thread pitch P is the axial distance from the end of the thread 14a of a certain single thread female thread 14 to the start position of the thread 14a of the next single thread. In the case of a single thread thread, the thread pitch P means the distance that the thread advances when it rotates once. On the other hand, in the case of a multiple thread thread, the thread pitch P is difficult to define as a constant distance because the advancement distance when it rotates once differs depending on the number of threads of the thread, so it is defined as above in this specification, but is not necessarily limited to the above definition.

[0082] The clearance calculation unit 211 stores the result of the clearance c derived at a plurality of predetermined locations, for example, four or eight locations, in the clearance database 221 as clearance information. The clearance c is derived for all threads 13a, 14a and thread roots 13b, 14b of the joined portions at a plurality of predetermined locations in the male joint 11 and the female joint 12. The minimum clearance c along the radial direction with respect to the rotation axis is then derived. Specifically, the clearance calculation unit 211 extracts a value at which the clearance c between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 is minimum in the rotation radial direction in each longitudinal section (see FIG. 7B) by using a predetermined measurement software. The derived information of the clearance c may be stored in the storage unit 22 in association with the thread joint identification ID of the pipe type information stored in the pipe type database 222.

[0083] (Clearance determination step) Next, the process proceeds to step ST414 as a clearance determination step, where the determination unit 212 of the control unit 21 reads out clearance information from the clearance database 221 of the storage unit 22 and determines whether or not joining is possible according to a predetermined criterion. That is, the determination unit 212 makes a determination based on, for example, the predetermined criterion, that is, whether or not the clearance c between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 is equal to or smaller than a predetermined value. The predetermined value can be set to any value, and in this embodiment, the predetermined value is set to 0, for example.

[0084] If the determination unit 212 determines in step ST414 that the clearance c between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 is equal to or less than a predetermined value, specifically, for example, equal to or less than 0 (c≦0) (step ST414: Yes), the process proceeds to step ST418. In step ST418, the determination unit 212 outputs information that the threaded joint 10 to be measured has failed, and stores this failure information as clearance information in the clearance database 221. This completes the clearance measurement process.

[0085] If the determination unit 212 determines in step ST414 that the clearance c between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 is greater than a predetermined value, specifically, for example, greater than 0 (c>0) (step ST414: No), the process proceeds to step ST415. That is, if the clearance c in the portion joined at multiple preset locations is greater than a predetermined value, it is determined that no interference occurs and the male joint 11 and the female joint 12 are joinable. Here, if the predetermined value is set to 0, the determination unit 212 can determine that no interference occurs and the male joint 11 and the female joint 12 are joinable if the clearance c is always positive (c=r2-r1>0). Incidentally, since the interference portion E may occur not only in the radial direction of the threaded portion but also in the axial direction of the threaded portion and in other locations than the threaded portion, it may be judged in the same manner. However, since the radial deformation of the threaded portion is most likely to occur in the threaded joint 10, the judgment unit 212 can judge that the threaded portion can be joined if the radial clearance of the threaded portion satisfies the above-mentioned condition (c>predetermined value). In addition, as a static examination, a method was adopted in which the examination was conducted by assuming that the overall shape of the joint is rigid and does not deform using measurement software or CAD, but as a dynamic examination, a method can also be adopted in which the shape of the joint is elastically deformed due to partial minute interference and frictional resistance are taken into consideration. As a dynamic examination, a dynamic analysis is performed using FEM, mechanism analysis, etc., and interference is judged based on fluctuations in load, torque, contact, friction, etc.

[0086] (Joint determination step) In step ST415 as a joining determination step, the determination unit 212 determines whether or not the male joint 11 and the female joint 12 are not screwed together and the joining is disengaged in the threaded joint 10. If the determination unit 212 determines that the male joint 11 and the female joint 12 are not screwed together and the joining is disengaged (step ST415: Yes), the process proceeds to step ST417.

[0087] In step ST417, the determination unit 212 outputs information that the threaded joint 10 being measured has passed, and stores this pass information as clearance information in the clearance database 221. The clearance calculation unit 211 can derive the clearance c for the entire circumference of the male thread 13 and the female thread 14 up to the state where the male joint 11 and the female joint 12 are virtually disengaged. This completes the clearance measurement process.

[0088] On the other hand, if the determining unit 212 determines in step ST415 that the male joint 11 and the female joint 12 are not separated and the connection is not released (step ST415: No), the process proceeds to step ST416.

[0089] (Rotation state setting step) In step ST416 as a rotational state setting step for performing a rotational state setting process, the clearance calculation unit 211 sets a state in which the joined male joint 11 and female joint 12 are rotated in the disengagement direction by a predetermined rotation angle, specifically, for example, 90° or 45°. Here, the rotational state setting step executed in step ST416 will be described in detail.

[0090] That is, the data-stored male joint 11 and female joint 12 are rotated from the completed joining state in the opposite direction to the rotation direction at the time of joining (hereinafter, "reverse rotation") to completely release them. If no interference occurs at all cross sections in all threaded portions of the male thread 13 and female thread 14 when releasing is virtually performed using this data, it can be determined that the male joint 11 and female joint 12 can be joined. Conversely, if interference occurs at least in some areas, i.e., if the clearance c is equal to or less than a predetermined value, it can be determined that they cannot be joined.

[0091] In this way, it is preferable to perform the judgment by reverse rotation starting from the joining completion state of the male joint 11 and the female joint 12, which is an important feature of the present embodiment. When deriving the interference degree while rotating the threaded joint 10 in the joining direction of the male thread 13 and the female thread 14 to be joined from the joining start state in which the male joint 11 and the female joint 12 are separated in the threaded joint 10, it is not always possible to start the rotation joining immediately from the position where the male joint 11 and the female joint 12 are contacted. In this case, it becomes necessary to repeatedly change the initial positions of the male joint 11 and the female joint 12 to search for an initial position where the rotation joining can actually be started. In contrast, when rotating in the reverse direction from the joining completion state as in the present embodiment, the initial positions of the male joint 11 and the female joint 12 are determined to be one position, so that the search for the rotation start position can be omitted. Here, when the joining confirmation is performed on the actual threaded joint 10 rather than on a digitalized one, it is possible to specify the initial position for starting the joining while moving it. When checking the joining on a digitized virtual system, it is necessary to search for the initial position for starting the joining by considering multiple settings in the circumferential direction, the axial direction, etc., and it is extremely difficult to rotate and join the male joint 11 and the female joint 12 on the virtual data. In contrast, it is relatively easy to identify the joining completion position. This simplifies and improves the efficiency of the measurement process of the threaded joint 10 by setting the joining completion position as the initial position and checking for the presence or absence of interference while releasing the joining by rotating in the reverse direction. In addition, interference is more likely to occur at positions where the male thread 13 and the female thread 14 are engaged in the fitting, that is, closer to the joining completion position. Therefore, by rotating in the reverse direction from the joining completion position to derive the degree of interference, the interference position can be found earlier.

[0092] As a specific procedure executed by the clearance calculation unit 211 in step ST416, first, the male joint 11 and the female joint 12, which have been converted into data, are virtually placed at the joining completion position as shown in FIG. 2. The rotation axes of the male joint 11 and the female joint 12 are extracted. Specifically, for example, a plurality of points, such as 4 points or 8 points, are selected for the outer diameter of the tip of the male joint 11 and the inner diameter of the tip of the female joint 12. Next, a fitting circle that minimizes the deviation from the selected points is created, and the center of the fitting circle is set as the rotation axis. The rotation axes of the male joint 11 and the female joint 12 are aligned to derive a state of shoulder touch. Here, the position of the eye mark is set as the joining completion position. Note that any method can be used to set the rotation axis and the joining completion position, and various methods other than the above-mentioned method can be used.

[0093] Next, in a state where the rotation axes of the male joint 11 and the female joint 12 are aligned and shoulder-touched, the minimum clearance along the radial direction of the rotation axis is derived for all the threads 13a, 14a in the longitudinal sections (see Figs. 7A to 7C) at an angle interval of, for example, 45° or 90° or less that is determined in advance. Here, the portion where the clearance is negative is also measured. In addition, the value where the clearance of the threaded portion of the male joint 11 and the female joint 12 in the rotation radius direction is minimum in each longitudinal section is extracted by the measurement software. More specifically, the overall minimum value is derived, or the minimum value is derived for each of the multiple threads of the threads 13a, 14a. Furthermore, depending on the conditions, visual observation or examination using representative points is also possible. In addition, the distance may be measured in the normal direction of the line connecting each point on the male joint 11, i.e., for each mesh, and the distance when it contacts the female joint 12 in the joined state, i.e., the shortest distance, may be set as the clearance c. Conversely, the distance may be measured in the direction from the female joint 12 to the male joint 11.

[0094] Thereafter, the threads are rotated in the opposite direction to the joining direction by a preset rotation angle. Here, the rotation angle may be, for example, 45° intervals or 90° intervals, but is not limited thereto. The amount of axial movement according to the angle of reverse rotation is determined by the thread pitch P of the male thread 13 and the female thread 14. The cross section for deriving the clearance and the intervals of reverse rotation are set to 45° or less or 90° or less because the threaded joint 10 is continuous in the circumferential direction, local deformation is unlikely to occur, and the presence or absence of interference can be sufficiently detected even if checking is performed at intervals of about 45° to 90°.

[0095] If interference occurs during reverse rotation, the rotating shaft of the male joint 11 is moved to the side with the larger clearance along the direction of the rotation radius, and the presence or absence of interference is confirmed at that stage. If further interference occurs, the rotating shafts of the male joint 11 and female joint 12 are moved in the axial direction to search for a position where no interference occurs. When a position where no interference occurs is identified, reverse rotation is started again from that position. Note that the presence or absence of interference may be determined without moving the rotating shaft.

[0096] The above procedure is repeated until the male joint 11 and the female joint 12 are rotated in the opposite directions and released from the connection. In this procedure, if the clearance between all the male threads 13 and the female threads 14 is greater than a predetermined value, for example, 0, it is determined that they can be connected, and if it is equal to or less than the predetermined value, it is determined that they cannot be connected.

[0097] After the rotation state setting step in step ST416 is completed, the process proceeds to step ST413, where the clearance c of the joined portion at a preset location is derived. The control unit 21 repeatedly executes steps ST413 to ST416 until the clearance c becomes equal to or less than a predetermined value (step ST414: Yes) or the male joint 11 and the female joint 12 are released from the joint (step ST415: Yes). Thereafter, the determination unit 212 stores pass / fail information of the threaded joint 10 to be measured as clearance information in the clearance database 221. This completes the clearance measurement process. According to the clearance measurement process of the first embodiment, the threaded joint 10 is determined to be a failure when the clearance c becomes equal to or less than a predetermined value, thereby shortening the time required to identify a failed product of the threaded joint 10.

[0098] Thereafter, the process proceeds to step ST5 shown in Fig. 5, where the control unit 21 outputs pass or fail information for the threaded joint 10 being measured to the input / output unit 23. For threaded joints 10 that have been determined to have failed, a mark may be placed on the actual threaded joint 10. For threaded joints 10 that have been determined to have failed, it is possible to appropriately select whether to carry out an adjustment process, which will be described later, or to discard the threaded joint. This completes the measurement process for the threaded joint.

[0099] Based on the above-described method for measuring a threaded joint, it is possible to control the quality of the threaded joint 10. That is, in the quality control method for the threaded joint 10, first, the threaded joint 10 is manufactured by a joint manufacturing process in step ST1. Next, the thread shapes of the male thread 13 and the female thread 14 of the threaded joint 10 are measured by a joint measurement process in step ST3. Thereafter, in step ST4, the measurement results obtained in the joint measurement process are used to measure the clearance for each pair of the male thread 13 and the female thread 14, thereby making it possible to control the quality of the threaded joint 10 as a quality control process.

[0100] (First Modification) Next, a first modified example of the clearance measurement process according to the first embodiment described above will be described. Fig. 10 is a flow chart for explaining the clearance measurement process according to the first modified example. In the clearance measurement method according to the first embodiment, the clearance measurement process is completed at the stage where a portion where the clearance is equal to or less than a predetermined value is found. In contrast, the clearance measurement process according to the first modified example is different from the clearance measurement process according to the first embodiment in that it is assumed that the entire circumference of the male joint 11 and the female joint 12 of the threaded joint 10 is measured regardless of whether the clearance measurement is pass or fail.

[0101] That is, as shown in FIG. 10, steps ST421 to ST423 are respectively the same as steps ST411 to ST413 in the first embodiment described above. In the first modified example, after execution of step ST423, the process proceeds to step ST424. In step ST424, clearance calculation unit 211 stores the result of clearance c derived at a plurality of preset locations, for example, four locations or eight locations, in clearance database 221 as clearance information. Thereafter, the process proceeds to step ST425. Steps ST425 and ST426 are respectively the same as steps ST415 and ST416 in the first embodiment. Also, in the first modified example, the process of determining whether or not the clearance is equal to or less than a predetermined value is not executed. Since the other processes are the same as those in the first embodiment, the description will be omitted.

[0102] (Second Modification) Next, a second modified example of the clearance measurement process according to the first embodiment described above will be described. Fig. 11 is a flow chart for explaining the clearance measurement process according to the second modified example. In the clearance measurement method according to the first embodiment, the clearance measurement process is completed at the stage where a portion where the clearance is equal to or less than a predetermined value is found. In contrast, the clearance measurement process according to the second modified example is different from the clearance measurement process according to the first embodiment in that it is assumed that the clearance is measured by measuring the entire circumference of the male joint 11 and the female joint 12 of the threaded joint 10 and then making a judgment based on a comparison with a predetermined value all at once, regardless of whether the clearance is equal to or less than the predetermined value.

[0103] That is, as shown in Fig. 11, steps ST431 to ST434 are respectively similar to steps ST421 to ST424 in the first modified example described above. In the second modified example, the process proceeds to step ST435 after execution of step ST434. In step ST435, clearance calculation unit 211 executes step ST435, which is a rotation state setting step similar to step ST416 in the first embodiment. The process proceeds to step ST436.

[0104] In step ST436, the determination unit 212 determines whether or not the connection has come apart in the same manner as in step ST415. If the determination unit 212 determines in step ST436 that the connection of the threaded joint 10 has not come apart (step ST436: No), the process proceeds to step ST433, and steps ST433 to ST436 are repeatedly executed. If the determination unit 212 determines in step ST436 that the connection of the threaded joint 10 has come apart (step ST436: Yes), the process proceeds to step ST437.

[0105] In step ST437, the determination unit 212 determines whether or not the clearance c between the male joint 11 and the female joint 12 is equal to or less than a predetermined value, in the same manner as in step ST414 in the first embodiment. If the determination unit 212 determines in step ST437 that there is no portion where the clearance c between the male joint 11 and the female joint 12 is equal to or less than the predetermined value (step ST437: No), the clearance measurement process ends. If the determination unit 212 determines in step ST437 that the clearance c between the male joint 11 and the female joint 12 is equal to or less than the predetermined value (step ST437: Yes), the process proceeds to step ST438 as an interference information assignment step. In step ST438, which is an interference information assignment step for performing an interference information assignment process, the determination unit 212 sets a flag as an interference location for a location where the clearance c is equal to or less than the predetermined value. Next, the determination unit 212 stores the flag related to the interference location in the clearance database 221 of the storage unit 22 as clearance information. This completes the clearance measurement process.

[0106] The clearance measurement process according to the first and second modified examples can be used when it is desired to set the clearance at the manufacturing site or when it is not necessary to obtain the clearance determination result in real time or in a short time. In particular, the clearance measurement process according to the second modified example makes it possible to provide a third party with clearance information such as positions where the clearance is equal to or less than a predetermined value or the absence of any portion where the clearance is equal to or less than a predetermined value. This makes it easier to handle cases where the clearance measurement process is performed at a location other than the manufacturing site.

[0107] According to the method for measuring the threaded joint 10 according to the first embodiment of the present invention described above, it is possible to check whether the threaded joint 10 can be joined after the manufacture of the threaded joint 10 is completed or before the joint is put into operation. Conventionally, the determination was made based on whether the male joint 11 and the female joint 12 could rotate, but the interference between the threads 13a and 14a can be checked as the clearance between the threads based on information on the measurement results, so accuracy can be ensured. In addition, since the measurement starts from the joining completion position of the threaded joint 10, there is no need to search for the starting position of the joining, and further, it is possible to find the interference point early, so that the measurement of the clearance of the threaded joint 10 can be started efficiently. Furthermore, regardless of the condition of the threads such as the length and size, it is possible to safely and simply check the joining in advance at the site such as a factory. The place where the measurement method for the threaded joint 10 according to this embodiment is used is not limited to a factory, but can also be used in a storage area at the construction site. Specifically, for example, if there is concern that the threaded joint 10 may be deformed due to damage caused by welding additional components, transportation, or excessive exposure to direct sunlight at the construction site, the shapes of the male joint 11 and the female joint 12 can be measured by the measuring unit 35 at the storage area at the construction site and a joint determination can be made before the actual joining, thereby minimizing the stoppage of on-site work due to problems.

[0108] Second Embodiment Next, a method for measuring a threaded joint according to a second embodiment of the present invention will be described. Fig. 12 is a flow chart for describing a method for measuring a threaded joint 10 according to the second embodiment. In the method for measuring a threaded joint 10 according to the second embodiment, after determining the clearance c over the entire circumference of the threads 13a, 14a in the male joint 11 and the female joint 12, a pass / fail determination is made for each threaded joint 10. Also, unlike the first embodiment, step ST414 (see Fig. 6), which serves as a clearance determination step, is separated from the clearance measurement step (step ST4) as a pass / fail determination step.

[0109] That is, as shown in Fig. 12, in the measurement method for a threaded joint 10 according to the second embodiment, steps ST1 to ST4 are executed as in the first embodiment. Then, instead of step ST5 according to the first embodiment, a pass / fail determination step is executed in step ST6. Furthermore, in the second embodiment, it is preferable to adopt the clearance measurement step according to the first or second modified example as the clearance measurement step in step ST4.

[0110] Specifically, in the pass / fail determination process in step ST6, the determination unit 212 determines whether the joining of the threaded joint 10 is pass / fail based on the clearance information of the entire circumference of the male thread 13 and the female thread 14 derived by the clearance calculation unit 211 in step ST4, for example, by executing steps ST423 and ST433. That is, the determination unit 212 reads and acquires the clearance information from the clearance database 221 in the storage unit 22, and determines whether the joining of the threaded joint 10 is pass / fail based on the acquired clearance information. As the criteria for the pass / fail determination by the determination unit 212, various criteria can be adopted. A method similar to that of step ST414 (see FIG. 6) as the clearance determination step described above can be used. Specifically, for example, it is determined whether the clearance c is equal to or less than a predetermined value. Here, the predetermined value is, for example, 0. In this case, if the parts that are equal to or less than the predetermined value, i.e., 0 or less or the parts that are 0 or less are considered to be interference parts, it is possible to determine that the parts that are equal to or more than a predetermined number are fail, and that the other parts are pass. Alternatively, a judgment can be adopted in which the presence of even one location below 0 or a location flagged as an interference location is deemed to be a failure, and the absence of even one location is deemed to be a pass. That is, in the clearance measurement process according to the third modified example, it is possible to judge pass / fail based on the number of locations where the clearance c is below a predetermined value or the number of flags indicating interference locations.

[0111] Furthermore, in the pass / fail determination step, similar to step ST438 in the second modified example, not only the pass / fail of the threaded joint 10 is determined, but also, based on the measured clearance c included in the clearance information, any location where the clearance c is equal to or less than a preset value may be flagged as an interference location. In this case, it is possible to determine, for example, that the joint is failed when the number of flags is equal to or greater than a preset number, and that the joint is passed when the number of flags is less than the preset number.

[0112] If the threaded joint 10 is judged to be pass in the pass / fail judgment process (step ST6: Yes), the process proceeds to step ST61, where the fact that the threaded joint 10 is pass can be output to the input / output unit 23 or the like, or transmitted to the outside via the communication unit 24 and the network 2. Accordingly, the threaded joint 10 that has been judged to be pass can be shipped. In the pass / fail judgment process was deemed unsuccessful If so (step ST6: No), the process proceeds to step ST62. The threaded joint 10 can be discarded and re-adjusted (Step ST62) In this case, the clearance information of the target threaded joint 10 can be associated with an identification ID of the threaded joint and transmitted to the thread machining device 40, 40A, as necessary.

[0113] According to the second embodiment, it is possible to obtain the same effects as in the first embodiment. Furthermore, according to the second embodiment, it is possible to use the clearance information to perform pass / fail judgments by an external processing device via the network 2, and to share information on the inspection results of the threaded joint 10.

[0114] (Third embodiment) Next, a method for measuring a threaded joint according to a third embodiment of the present invention will be described. Fig. 13 is a flowchart for explaining a method for measuring a threaded joint 10 according to the third embodiment. The method for measuring a threaded joint 10 according to the third embodiment differs from the first embodiment in that an adjustment step is carried out after a clearance measurement step in step ST4.

[0115] That is, as shown in Fig. 13, in the measurement method for a threaded joint 10 according to the third embodiment, steps ST1 to ST4 are performed as in the first embodiment. Then, instead of step ST5 in the first embodiment, an adjustment step is performed in step ST7. Also, in the third embodiment, the clearance measurement step in step ST4 can be the clearance measurement step according to the first embodiment, the first modified example, or the second modified example.

[0116] (adjustment process) Next, the adjustment process in step ST7 will be described. As shown in Fig. 13, for a threaded joint 10 that has been determined to be unacceptable or to have an interference portion based on the measured clearance c, the adjustment process is executed after the clearance measurement process. The adjustment process includes adjustment steps, which will be described later. Note that, if no pass or fail information is output in the clearance measurement process executed in the preceding stage, step ST6 (pass / fail determination process) according to the second embodiment may be executed before each adjustment step, which will be described later, in step ST7.

[0117] (Adjustment steps) In step ST7, which is the adjustment process for the threaded joint 10, the set of threaded joints 10 that require adjustment is judged to be acceptable. (Step ST7: Yes) The shape measurement process, the clearance measurement process, and the adjustment process can be repeatedly performed until (Step ST7: No) Furthermore, within the adjustment process, it is also possible to execute a pass / fail determination step prior to the adjustment step. As the adjustment step, an appropriate method can be appropriately selected from, for example, four methods depending on the specifications and purpose of the threaded joint 10 and can be adopted.

[0118] That is, the first method in the adjustment step is to virtually change the joining start position when there are multiple joining start positions for the threaded joint 10, for example, when it is configured with a multiple start thread, and to perform a pass / fail judgment process by the judging unit 212. Here, when the pass / fail judgment process is passed, the completion and start positions are marked at positions corresponding to the actual one.

[0119] Next, the second method in the adjustment step is a method in which the pass / fail judgment process is carried out again on the threaded joint 10 whose thread shape has been modified, taking into consideration cutting a portion of the threaded joint 10 virtually within a range that satisfies the strength required for the male joint 11 and the female joint 12, and a pass / fail judgment is made. If the interference is small, it is possible to cut the actual part with a grinder or the like when the virtually passed the test, taking into consideration cutting within a safety factor of, for example, about 1.2. The above first and second methods are methods that do not require another 3D scan operation by the measurement unit 35.

[0120] Next, the third method in the adjustment step is to correct a part of the actual threaded joint by correction due to thermal deformation, measure it again by the measuring unit 35, and perform the pass / fail judgment process again to make a pass / fail judgment. Note that the correction due to thermal deformation is performed by welding heat or burner heating, and, if necessary, compression or tension using a jack.

[0121] Next, the fourth method in the adjustment step is to manufacture a new threaded joint 10, measure it again by the measuring unit 35, and then perform the pass / fail determination step again to make a pass / fail determination. Note that manufacturing a new threaded joint 10 does not only mean new manufacture, but also includes, in the case of a steel pipe with a joint, removing the threaded joint 10 from the pipes 15, 16 and reattaching it. Note that, when there are multiple identical threaded joints 10, it is possible to make threaded joints that pass the pass / fail determination step by changing the combination of the corresponding male and female joints.

[0122] According to the third embodiment, it is possible to obtain the same effects as those of the first embodiment. Furthermore, according to the third embodiment, by including an adjustment process, it is possible to adjust the threaded joint 10 to an acceptable product through a new adjustment process.

[0123] (Fourth embodiment) Next, a fourth embodiment will be described. In the fourth embodiment, a threaded joint measurement system 1A according to the second example of the embodiment is adopted as a threaded joint measurement system, and the clearance measurement process according to the first embodiment is adopted. In the fourth embodiment, the clearance measurement device 20A can be configured as a fixed information processing device, or as a server capable of communicating with the measurement terminal 30A via the network 2. In this case, the measurement terminal 30A is configured as a terminal having a communication unit 34 and an independent measurement unit 35 capable of communicating with the clearance measurement device 20A via the network 2.

[0124] Here, the control unit 31 of the measurement terminal 30A can output the clearance information transmitted from the clearance measurement device 20A by displaying it on the input / output unit 33. Note that as the clearance information to be displayed on the input / output unit 33, various information can be output, such as the pass / fail result of the threaded joint 10, and an enlarged display of a cross-sectional view of an interference point between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12.

[0125] Furthermore, the control unit 31 can select various information received from the clearance measurement device 20A via the network 2 and output it from the input / output unit 33. For example, even if clearance information including both pass and fail information is transmitted from the clearance measurement device 20A to the measurement terminal 30A, the control unit 31 can control so that a failure is output from the input / output unit 33 only when a fail is transmitted. Furthermore, since the measurement terminal 30A can communicate with the thread machining device 40A via the communication unit 34 and the network 2, the thread machining device 40A can supply clearance information from the measurement terminal 30A to the thread machining device 40A via the clearance measurement device 20A to correct the interference location.

[0126] Fifth embodiment Next, a fifth embodiment will be described. In the fifth embodiment, a threaded joint measurement system 1A according to a second example of the embodiment is adopted as a threaded joint measurement system. In addition, a threaded joint measurement method according to the second embodiment shown in FIG. 12 is adopted as a method for measuring a threaded joint 10. In this case, it is preferable to adopt the clearance measurement process according to the first or second modified example. In the fifth embodiment, the clearance measurement device 20 can be configured from a fixed information processing device, or from a server capable of communicating with the measurement terminal via the network 2. In this case, the measurement terminal 30A is configured from an independent terminal capable of communicating with the clearance measurement device 20 via the communication unit 34 and the network 2.

[0127] In the fifth embodiment, control unit 31 of measurement terminal 30A has a function similar to that of determination unit 212 in control unit 21 of clearance measurement device 20A. Note that control unit 31 may be configured to be able to execute processing similar to that of determination unit 212 of clearance measurement device 20A through communication with clearance measurement device 20A. In this case, control unit 31 of measurement terminal 30A can execute the bonding determination step in step ST6 shown in FIG. 12 based on the clearance information received from clearance measurement device 20A.

[0128] In the fourth and fifth embodiments, the measurement terminal 30A can be used independently, making it possible to carry out measurement and pass / fail judgment of the threaded joint 10 at various sites.

[0129] Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned embodiment, and various modifications based on the technical concept of the present invention are possible. For example, the numerical values ​​and materials given in the above-mentioned embodiment are merely examples, and numerical values ​​and materials different from these may be used as necessary.

[0130] For example, in each of the above-mentioned embodiments and modifications, the determination unit 212 makes a determination based on whether the clearance c between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 is equal to or less than a predetermined value as the predetermined criterion, but this is not limited thereto, and the determination may be made based on whether the clearance c is less than a predetermined value as the predetermined criterion. Similarly, "Yes" and "No" in step ST414 and step ST437 may be interchanged based on whether the clearance c is equal to or greater than a predetermined value or exceeds a predetermined value as the predetermined criterion. Even in these cases, the predetermined value can be set to a value equal to or greater than 0.

[0131] For example, the method of measuring a threaded joint according to the above-described embodiment can be performed manually or automatically using shape measurement software applied to a handheld 3D scanner, high-end CAD, etc. When performed automatically, the repeated processes of steps ST413 to ST416 and steps ST423 to ST426 described above can be executed using a software program by the control unit 21 of the clearance measurement device 20. This can achieve even greater efficiency in the method of measuring a threaded joint. [Industrial Applicability]

[0132] The clearance measurement method, clearance measurement device, threaded joint measurement method, threaded joint measurement system, measurement terminal, threaded joint manufacturing method, and threaded joint quality control method according to the present invention are suitable for application to steel pipe joint structures for joining steel pipes. [Explanation of symbols]

[0133] 1,1A Threaded Joint Measurement System 2 Network 10 Threaded joints 11 Male connector 12 Female fitting 13 Male thread 13a,14a Thread 13b,14b screw bottom 14 Female thread 15 tubes 20,20A Clearance measuring device 21, 31, 41 Control section 22,32,42 Storage section 23,33,43 Input / output section 24,34,44 Communications Department 30A Measurement Terminal 35 Measurement section 40,40A Thread processing device 45 Thread processing section 211 Clearance calculation unit 212 Judgment section 221 Clearance Database 222 Pipe Type Database 311 Measurement control section 411 Processing control section

Claims

1. A clearance measurement method for measuring a clearance between a thread of a male joint and a thread of a female joint corresponding to the male joint, the method comprising the steps of: a joining completion state setting step of setting a joining completion state in which joining of the male joint and the female joint is completed based on data of the respective thread shapes of the male joint and the female joint; a clearance measuring step of measuring a clearance between a thread of the male joint and a thread of the female joint corresponding to the thread of the male joint in the joined state; a rotation state setting step of setting a state in which the male joint and the female joint are rotated by a predetermined angle in a direction to release the joint, if the joint is not in a released state after the clearance measurement step; Equipped with The steps from the clearance measuring step to the rotation state setting step are repeatedly executed until the joint is released. Clearance measurement method.

2. A step of determining whether the set of threaded joints is pass or fail based on the clearance measured in the clearance measurement step and a predetermined criterion; and an interference information providing step of providing information on an interference portion to a portion determined to be an interference portion based on the clearance measured in the clearance measuring step and a predetermined criterion. The clearance measurement method according to claim 1 .

3. a shape measuring process for measuring the thread shape of the male joint and the thread shape of the female joint for a set of threaded joints having a male joint and a female joint corresponding to the male joint; a clearance measurement step of measuring a clearance for each pair of the threaded joints by the clearance measurement method according to claim 1 or 2, based on data of the thread shape measured in the shape measurement step; Equipped Measurement methods for threaded joints.

4. A method for manufacturing a threaded joint, comprising the steps of: manufacturing a set of threaded joints having a male joint and a female joint corresponding to the male joint, a joint manufacturing process for manufacturing a threaded joint; a joint measurement process for performing the threaded joint measurement method according to claim 3 on the set of threaded joints having a male joint and a female joint produced by the joint manufacturing process; Equipped A method for manufacturing a threaded joint.

5. A quality control method for a threaded joint, which controls the quality of a set of threaded joints having a male joint and a female joint corresponding to the male joint, a joint manufacturing process for manufacturing the threaded joint; a joint measurement process for measuring a thread shape of the threaded joint by the threaded joint measurement method according to claim 3 for the set of threaded joints produced by the joint manufacturing process; A quality control process for controlling the quality of the created threaded joint using the results obtained from the joint measurement process; Equipped Quality control methods for threaded joints.

6. A clearance measurement device for measuring a clearance between a thread of a male joint and a thread of a female joint corresponding to the male joint for a set of threaded joints, the clearance measurement device comprising: a joining completion state setting process for setting a joining completion state in which joining of the male joint and the female joint is completed based on data of the thread shapes of the male joint and the female joint, respectively; a rotation state setting process for setting a state in which the male joint and the female joint are rotated by a predetermined angle in a direction to release the joint when the male joint and the female joint are not in a released state after a clearance between the threads of the male joint and the threads of the female joint corresponding to the threads of the male joint is measured in the joined state; A control unit is provided which repeatedly executes the above-mentioned process until the joining is released. Clearance measuring device.

7. The control unit is A clearance measurement process is executed to measure a clearance between a thread of the male joint and a thread of the female joint corresponding to the thread of the male joint in the joining completed state before the rotation state setting process. The clearance measurement device according to claim 6.

8. Further, a communication unit is provided, The communication unit, by the control unit, At least one of the following is executed: acquiring data on the thread shapes of the male joint and the female joint; and outputting information on the clearance obtained by a clearance measurement process that measures a clearance between the thread of the male joint and the thread of the female joint corresponding to the thread of the male joint in the joining completed state. The clearance measurement device according to claim 6.

9. A measurement unit configured to be able to measure the thread shape of the male joint and the thread shape of the female joint for a set of threaded joints having a male joint and a female joint corresponding to the male joint; The clearance measurement device according to any one of claims 6 to 8, which measures a clearance for each pair of the threaded joints based on data of the thread shape measured by the measurement unit; Equipped Measurement system for threaded joints.

10. A measurement terminal configured to be capable of measuring a clearance between a thread of a male joint and a thread of a female joint corresponding to the male joint for a set of threaded joints, the measurement terminal being controlled by a control unit, A measuring unit that measures the thread profile of the male joint and the thread profile of the female joint under the control of the control unit; A communication unit that executes at least one of an output process of outputting the measured thread shape as data to the clearance measurement device according to any one of claims 6 to 8 under the control of the control unit, and an acquisition process of acquiring information regarding the clearance for each pair of the threaded joint from the clearance measurement device; an output unit capable of outputting the acquired information in a predetermined format under the control of the control unit; Equipped Measurement terminal.

11. The control unit is A process of determining whether the set of threaded joints is pass or fail based on the acquired information on the clearance and a predetermined criterion; and an interference information assignment process for assigning information about an interfering portion to a portion determined to be an interfering portion based on the acquired information about the clearance and a predetermined criterion. The measurement terminal according to claim 10.

12. A measurement terminal configured to be capable of measuring the clearance between the threads of a male joint and the threads of a female joint for a pair of threaded joints having a male joint and a female joint corresponding to the male joint, and controlled by a control unit, the measurement terminal comprising: a measurement unit that measures the thread shape of the male joint and the thread shape of the female joint, respectively, under the control of the control unit; a communication unit that executes at least one of the following processes: an output process that outputs the measured thread shape as data to a clearance measuring device, under the control of the control unit, and an acquisition process that acquires information regarding the clearance from the clearance measuring device for each pair of threaded joints; and an output unit that is capable of outputting the acquired information in a predetermined format under the control of the control unit; a control means for repeatedly executing a joining completion state setting process for setting a joining completion state in which joining of the male joint and the female joint is completed based on data on the thread shapes of the male joint and the female joint, and a rotation state setting process for setting a state in which the male joint and the female joint have been rotated a predetermined angle in a direction to release the joining, if the joining of the male joint and the female joint is not in a disengaged state after the clearance between the thread of the male joint and the thread of the female joint corresponding to the thread of the male joint has been measured in the joining completion state, until the joining is in a disengaged state; and Equipped Measurement system for threaded joints.

13. A quality control method for a threaded joint for controlling the quality of a threaded joint for a set of a threaded joint having a male joint and a female joint corresponding to the male joint, The quality of the set of threaded joints is managed using information on the clearance obtained from the clearance measurement process executed by the control unit of the clearance measurement device according to any one of claims 6 to 8. Quality control methods for threaded joints.

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