Clearance measurement method, clearance measurement device, threaded joint measurement method, threaded joint measurement system, measurement terminal, threaded joint manufacturing method, and threaded joint quality management method

Abstract

The purpose of the present invention is to efficiently check joining in a pipe with a threaded joint. A clearance measurement method for measuring a clearance between a thread of a male joint and a thread of a female joint in a set of threaded joints having the male joint and the female joint corresponding to the male joint, the method comprising: an initial state setting step for setting an initial state of the male joint and the female joint on the basis of data on the thread shapes of the male joint and the female joint, respectively; a clearance measurement step for 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 initial state; and a rotation state setting step for setting a state in which rotation is performed by a predetermined angle in the direction in which joining is to be performed in the case where the joining of the male joint and the female joint has not been completed after the clearance measurement step. The steps from the clearance measurement step to the rotation state setting step are repeatedly executed until joining is completed.

Description

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

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

[0002] Conventionally, pipe structures used for building foundations and preventing landslides can require lengths of several tens of meters depending on the construction conditions. This tendency is particularly pronounced for steel pipes. When transporting these pipe structures to the construction site, traffic restrictions prevent the transport of long pipes. Therefore, they are transported in transportable lengths of several meters at a time, and then joined at the construction site during construction (including pouring).

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

[0004] Generally, threaded joints are pre-attached at the factory, with the male joint attached to one pipe and the female joint attached to another 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 joint sets may be attached to the end of a long pipe depending on their intended use.

[0005] Japanese Patent Application Publication No. 10-311028

[0006] Because the feasibility of a threaded joint is determined by the corresponding thread shapes of the male and mating female joints, 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 (5 m or more), or when the threaded joint or the connected pipe is heavy and made of a metal material such as steel, checking the joint becomes difficult. In such cases, there are problems such as the significant effort required for checking the joint, the risk of damage to the joint itself, and concerns about safety.

[0007] In particular, in the case of threaded joints, there may be locations where the clearance (also referred to as 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 complete. 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 need for a technology that can more easily determine whether a thread shape of a threaded joint is joinable 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 view of the above, and its object is to provide a clearance measurement method, a clearance measurement device, a threaded joint measurement method, a threaded joint measurement system, a measurement terminal, a threaded joint manufacturing method, and a threaded joint quality control method that enable joining confirmation in a threaded joint to be performed more easily regardless of the state of the threaded joint or the state of the connected pipe.

[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 threads of a male joint and a female joint corresponding to the male joint for a set of threaded joints having the male joint and the female joint, the clearance measurement method comprising: an initial state setting step for setting an initial state of the male joint and the female joint based on data of the thread shapes of the male joint and the female joint, respectively; a clearance measurement step for measuring, in the initial state, the clearance between the threads of the male joint and the threads of the female joint corresponding to the threads of the male joint; and a rotational state setting step for setting a state in which the male joint and the female joint have been rotated a predetermined angle in the direction in which the joining is to be performed, if the joining of the male joint and the female joint has not been completed after the clearance measurement step; and the clearance measurement step through the rotational state setting step are repeatedly performed until the joining is completed.

[0010] (2) A clearance measurement method according to one aspect of the present invention, in the invention described in (1) above, includes at least one of 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 assignment step of assigning information about an interference location to a location that has been determined to be an interference location 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 aspect of the present invention includes a shape measurement step of measuring the thread shape of a male joint and a female joint corresponding to the male joint, respectively, for a set of threaded joints. The shape measurement step measures the thread shape of the male joint and the thread shape of the female joint, and a clearance measurement step measures the clearance for each set of threaded joints using the clearance measurement method according to the invention described in (1) or (2) above, based on data on the thread shape measured in the shape measurement step.

[0012] (4) A method for manufacturing a threaded joint according to the present invention is a method for manufacturing a threaded joint that manufactures a set of threaded joints having a male joint and a female joint that corresponds to the male joint, and includes a joint manufacturing process that manufactures a threaded joint, and a joint measurement process that performs the threaded joint measurement method according to the invention described in (3) above on the set of threaded joints having a male joint and a female joint that have been manufactured by the joint manufacturing process.

[0013] (5) A quality control method for a threaded joint according to one aspect 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 that corresponds to the male joint, and includes: a joint manufacturing process for manufacturing the threaded joint; a joint measurement process for measuring the thread shape of the set of threaded joints created by the joint manufacturing process using the threaded joint measurement method according to the invention described in (3) or (4) above; and a quality control process for controlling the quality of the created 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 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, and a rotational state setting process that, if the joining of the male joint and the female joint is not completed in the joining completion state after the clearance between the threads of the male joint and the threads of the female joint corresponding to the threads of the male joint has been measured, sets a state in which the male joint and the female joint are rotated by a predetermined angle in the direction in which the joining is to be performed, until the joining is completed.

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

[0016] (8) A clearance measurement device according to one aspect of the present invention is the invention described in (6) or (7) above, further comprising a communication unit, and the communication unit executes, via the control unit, at least one of a process for acquiring data on the thread shapes of the male joint and the female joint, and a process for outputting information relating to the clearance obtained by the clearance measurement process.

[0017] (9) A threaded joint measurement system according to one aspect 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 any one of the inventions described in (6) to (8) above, which measures the clearance for each set of threaded joints based on data on the thread shape measured by the measurement unit.

[0018] (10) A measurement terminal according to one aspect of the present invention is a measurement terminal configured to be able to measure 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 controlled by a control unit, and is equipped with: 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 invention described in any one of (6) to (8) above under the control of the control unit, and an acquisition process that acquires information regarding the clearance from the clearance measurement device for each set 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.

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

[0020] (12) A measurement system for a threaded joint according to the present invention comprises a measurement terminal according to the invention described in (10) or (11) above, and a clearance measurement device according to the invention described in any one of (6) to (8) above that measures the clearance for each pair of the threaded joint based on data on the thread shape measured by the measurement terminal.

[0021] (13) A quality control method for a threaded joint according to one aspect 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 about the clearance obtained from a clearance measurement process executed by a control unit of a clearance measurement device according to the invention described in any one of (6) to (8) above.

[0022] 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 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.

[0023] FIG. 1 is a diagram showing the start state of welding of a threaded joint that is the object of measurement in a threaded joint measurement system according to an embodiment of the present invention. FIG. 2A is a diagram showing the completed state of welding of a threaded joint that is the object of measurement in a threaded joint measurement system according to an embodiment of the present invention. FIG. 2B is a diagram showing the initial state of a threaded joint that is the object of measurement in a threaded joint measurement system according to an embodiment of the present invention. FIG. 3 is a block diagram showing a threaded joint measurement system according to a first example embodiment of the present invention. FIG. 4 is a block diagram showing a threaded joint measurement system according to a second example embodiment of the present invention. FIG. 5 is a flowchart for describing a threaded joint measurement method according to a first embodiment of the present invention. FIG. 6A is a flowchart for describing a clearance measurement process according to the first embodiment of the present invention. FIG. 6B is a flowchart for describing an initial state setting process of the clearance measurement process according to the first embodiment of the present invention. FIG. 7A is a diagram for describing the coordinates of a threaded joint in the clearance measurement method according to an embodiment of the present invention. FIG. 7B is a diagram for describing the coordinates of a threaded joint in the clearance measurement method according to an embodiment of the present invention. FIG. 7C is a diagram for describing the coordinates of a threaded joint in the clearance measurement method according to an embodiment of the present invention. 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 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 is a flowchart for explaining a first modified example of the clearance measurement step in the clearance measurement method according to the first embodiment of the present invention. Figure 11 is a flowchart for explaining a second modified example of the clearance measurement step in the clearance measurement method according to the first embodiment of the present invention. Figure 12 is a flowchart for explaining a measurement method of a threaded joint according to a second embodiment of the present invention. Figure 13 is a flowchart for explaining a measurement method of a threaded joint according to a third embodiment of the present invention.

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

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

[0026] (Male joint and female joint to be measured) As shown in FIG. 1 , the threaded joint 10 according to this embodiment is configured to include a male joint 11 serving as an inner joint and a female joint 12 serving as an outer joint. A male thread 13 is formed on the tip side of the male joint 11, which is the side into which the male joint 11 is inserted and fitted. A female thread 14 is formed on the tip side of the female joint 12, which is the side into which the male joint 11 is inserted and fitted. The female thread 14 formed on the female joint 12 is formed with 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 threading. Note that both known and unknown thread shapes can be used. The thread shape can be single-start or multiple-start, and in this embodiment, for example, multiple-start. The thread shape can also be a tapered thread or a straight thread, and in this embodiment, for example, a straight thread. Furthermore, the material is not particularly limited. Examples include steel, metal materials other than steel, concrete, resin, or a combination of multiple materials. The material of the threaded joint is selected depending on the intended use and the conditions of the pipe, 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 structural body. The pipe 15 constitutes an upper structure. The pipe 16 constitutes a lower structure. Various structures can be employed as the structural body, such as those that have a predetermined function when buried in the ground, those that are used as part of an above-ground structure, and those that transport gases or liquids by utilizing the internal space of the pipes 15 and 16. Examples of structures that have 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 structures that are used as part of an above-ground structure include columns and beams. Examples of structures that transport gases or liquids by utilizing the internal space of the pipes 15 and 16 include oil well pipes, water pipes, and gas pipes. Furthermore, 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, making it difficult to check the joint before shipping 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. Furthermore, the male fitting 11 and female fitting 12 may be used as the measurement object without connecting the pipes 15 and 16.

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

[0030] As shown in Figure 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 also be configured to include 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.

[0031] (Clearance measurement device) Clearance measurement device 20 includes control unit 21, storage unit 22, and input / output unit 23. It is also possible to omit input / output unit 23. Clearance measurement device 20 can be a known computer, server, laptop computer, mobile terminal, tablet, smartphone, or a virtual device on a network such as a cloud.

[0032] The control unit 31 as a control means specifically includes a processor such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an FPGA (Field-Programmable Gate Array) having hardware, 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 volatile memory such as RAM, non-volatile memory such as ROM, erasable programmable read-only memory (EPROM), hard disk drive (HDD), solid state drive (SSD), and removable media. The removable media may be, for example, a universal serial bus (USB) memory or a disc storage medium such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray disc (BD). The storage unit 22 may also be configured using a computer-readable storage medium such as an externally attachable 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 may include learning models and neural networks. These various programs can also be recorded on computer-readable recording media such as hard disks, flash memories, CD-ROMs, DVD-ROMs, and flexible disks 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, as basic information, various pieces of information (pipe type information) related to the male joint 11 and the female joint 12 that make up the threaded joint 10 in a searchable manner. The pipe type information includes information such as the identification ID of the threaded joint 10, 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, in a searchable manner, information related to the clearance between the male thread 13 and the female thread 14 based on the pipe type information, and information on measurement results related to the clearance between the male thread 13 and the female thread 14 measured by a measurement unit 35 (described later) (hereinafter referred to as clearance information). In addition to information on the clearance measurement results, the clearance information includes various types of information related to 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 may be used.

[0036] In this embodiment, the control unit 21 loads a program stored in the storage unit 22 into a working area of ​​the main storage unit, executes the program, and controls each component through the execution of the program, thereby realizing functions that meet a predetermined purpose. Specifically, the control unit 21 can realize the functions of the clearance calculation unit 211 and the determination unit 212 through the execution of the program.

[0037] The input / output unit 23 is composed of, for example, a touch panel display, a speaker / microphone, buttons, switches, 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 audio 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 on a display of the input / output unit 23 installed in, for example, a predetermined office.

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

[0039] (Measurement Unit) The measurement unit 35 is composed of at least one device, such as a handheld 3D scanner. Examples of the 3D scanner that can be used include a laser irradiation device and an infrared irradiation device. Handheld 3D scanners must be operated while maintaining a focal length (e.g., 20 cm to 40 cm) appropriate for the model, so it is desirable to secure a space of 50 cm or more around the object to be scanned.

[0040] From the perspective of determining whether the male joint 11 and the female joint 12 can be joined, the measurement accuracy of the measurement unit 35 is preferably less than half the desired clearance. Specifically, for example, if the clearance is 0.75 mm, it is preferably less than (0.75 / 2 =) 0.375 mm. The measurement accuracy is set according to the size of the threaded joint 10 and the thread shapes of the male and female threads 13 and 14, and is not limited to these values. In particular, since the threaded joint 10 has a three-dimensional shape, blind spots are likely to occur due to unevenness. Therefore, from the perspective of operability, a handheld measuring device, such as a handheld 3D scanner, is desirable. Note that, among handheld 3D scanners, high-precision types typically require markers for shape measurement to be attached to the target object approximately every 10 cm. In contrast, when the threaded joint 10 is large, a markerless handheld 3D scanner that does not require markers for shape measurement is desirable from the perspective of efficiency.

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

[0042] Furthermore, when selecting equipment for the measuring unit 35, the higher the resolution, the more preferable. In this case, the resolution should be sufficient to accurately reproduce the shape of the threads, which 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 are unlikely to occur in the shape of the male thread 13 or the female thread 14, the resolution should be approximately 1 mm or less, but is not limited to this value. Furthermore, 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 directionality by providing a marker or shape mark that can be recognized by scanning.

[0043] The measurement unit 35 outputs 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 machining device) The thread machining device 40 is a device used in an adjustment process for the male threads 13 and female threads 14 of the threaded joint 10. The thread machining device 40 includes a control unit 41, a memory unit 42, an input / output unit 43, and a thread machining unit 45. The control unit 41, the memory unit 42, and the input / output unit 43 are configured functionally and physically in the same manner as the control unit 21, the memory unit 22, and the input / output unit 23, respectively. The thread machining device 40 is connected to the clearance measurement device 20.

[0045] The control unit 41 loads a program stored in the storage unit 42 into a working area of ​​the main storage unit, executes the program, and controls each component through the execution of the program, thereby realizing a function that meets a predetermined purpose. 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 clearance information from the clearance database 221 stored in the memory unit 22 and outputs it to the thread machining device 40. After acquiring the clearance information, the thread machining device 40 stores the acquired clearance information at least temporarily in the memory unit 42. When an instruction to correct an interference location of the male thread 13 or the female thread 14 is input from an operator or the like via the input / output unit 43, the machining control unit 411 of the control unit 41 controls the thread machining unit 45 to perform a machining process to correct the interference location based on the acquired clearance information. The thread machining device 40 may be configured integrally with the clearance measurement device 20. Furthermore, the thread machining device 40 can also be used to manufacture the threaded joint 10. As described above, a threaded joint measurement system 1 according to a first example embodiment is configured.

[0047] (Second Example of 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 the threaded joint measurement system according to the second embodiment. As shown in Fig. 4, a threaded joint measurement system 1A is configured to include a clearance measurement device 20A and a measurement terminal 30A that are capable of communicating with each other via a network 2.

[0048] The network 2 is, for example, a public communication network such as the Internet, and is made up of one or a combination of a local area network (LAN), a wide area network (WAN), a telephone communication network such as a mobile phone, a public line, a virtual private network (VPN), 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 40A that is capable of communicating with at least the clearance measurement device 20A via the network 2. The threaded joint measurement system 1A may also employ a configuration that includes the clearance measurement device 20, the measurement terminal 30A, and the thread processing device 40.

[0050] (Clearance measurement 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 the 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 remaining configuration is the same as that of the clearance measurement device 20 in the first embodiment.

[0051] (Measurement 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 functions that meet a predetermined purpose by loading a program stored in the storage unit 32 into a work area of ​​the main storage unit and executing the program. Specifically, the control unit 31 can realize the functions 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 machining device) The thread machining device 40A includes a control unit 41, a storage unit 42, an input / output unit 43, a communication unit 44, and a thread machining 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 machining device 40 in the first embodiment. As described above, a threaded joint measurement system 1A according to a second example of an embodiment is configured.

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

[0055] (Threaded Joint Manufacturing Process) As shown in FIG. 5 , first, in step ST1, the thread machining device 40 performs the joint manufacturing process. In step ST1, a forged ring is manufactured by heat treatment. Next, the forged ring is rotated by rotary cutting, and a cutting blade is brought into contact with the forged ring to cut it, thereby machining it into a joint. The movement of the cutting blade can be automatically controlled by the machining control unit 411 according to a predetermined program. Here, for example, if the thread shape of the joint is a multiple-start thread, cutting is performed little by little in the same location until one start is completed. Once one start is completed, the cutting blade is moved to the next start. After the threads of the joint are completed, a test joint is actually performed, and the arrival line is marked with an eye mark when the joint is completed and meets the structural performance. Then, the joints are released, and an arrow is marked on the start line on the outer circumferential surface of each joint (selecting a non-threaded portion), and an arrow is marked on the male joint 11 that corresponds to the eye mark on the female joint 12 upon release. It is not always necessary to use a forged ring, and a steel pipe or the like having a thickness that can be cut may also be used.

[0056] (Pipe connecting process) Next, the process proceeds to step ST2, where the pipe connecting 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, in this case, 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 this trial joining reaches the reach line, the joining is released. Next, the other joint of the male joint 11 or the female joint 12, in this case, 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 threaded joint and a steel pipe, this test joining 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 threaded joint and a pipe with a steel pipe sheet pile, for example, the steel connecting joint that connects the steel pipes horizontally is welded, and then the threaded joint is welded to the steel pipe. It is also possible not to perform this step ST2.

[0058] (Method for measuring a threaded joint) Here, a method for measuring a threaded joint according to this embodiment will be described. This embodiment includes a shape measurement step of measuring the shape of the threaded joint after processing, and a clearance measurement step for the 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 performing step ST1 or step ST2, the process proceeds to step ST3, where the shape measurement process is performed. In the shape measurement process, first, the measurement unit 35 measures the thread shapes of the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 for the set of threaded joints 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] Furthermore, 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, point cloud data is acquired using a handheld 3D scanner constituting the measurement unit 35, and the acquired point cloud data is then polygonized (STL, meshed), and shape measurement and virtual placement are performed using CAD software that performs 3D measurement of the target threaded joint 10. Here, to realize virtual placement, for example, when grasping the shape in detail, it is preferable to use the apex of the thread as a data point. That is, to measure the shape of the thread, it is preferable that the apex of the thread be included in the data points of the point cloud data. In practice, it is preferable that the resolution be less than the radius of curvature of the apex of the thread, for example, about 0.5 mm or less.

[0061] However, in some cases, the shape of the thread is unlikely to produce localized irregularities, and considering that the contact that affects joinability is planar contact on the thread surface, a resolution of about 1 mm may be used. Also, for example, by setting the accuracy of the data points to less than half the clearance, specifically, for example, 0.375 mm or less if the clearance is 0.75 mm, a determination can be made with sufficient accuracy for practical use.

[0062] Furthermore, since CAD software that performs three-dimensional measurements is used and the male joint 11 and female joint 12 are considered to be rigid bodies when making the joint judgment, there is no problem with a pass / fail judgment if there is clearance, but even if there is a certain degree of interference, the joints may be able to fit together due to their ability to deform as elastic bodies.

[0063] From the above, it is possible to improve the accuracy of judgment by setting a judgment standard value that takes into account measurement accuracy, ignoring local contact, frictional resistance, amount of elastic deformation, and usage conditions (directivity when joining, such as vertical, horizontal, or diagonal, and outside temperature) (it does not necessarily have to be based on 0, and for example, a digital clearance of -0.2 mm (virtual interference amount of 0.2 mm) can be used as the standard to judge whether or not the fit can be made. 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 standard). Note that whether the clearance is positive or negative depends on the method of sorting, so a negative value can be used to indicate that a clearance exists.

[0064] Furthermore, it is not necessary to measure the entire threaded joint 10; it is sufficient that the outer surface of the male joint 11 and the inner surface of the female joint 12 are measured by the measurement unit 35. In this case, it is possible to shorten the measurement time and reduce the volume 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, moving to step ST4, the clearance measurement process as a clearance measurement method will be described. Fig. 6A is a flowchart showing the clearance measurement process according to the first embodiment, and Fig. 6B is a flowchart showing a method for setting the initial state of the clearance measurement process according to the first embodiment. The flowcharts shown in Figs. 6A and 6B are executed by clearance measurement device 20.

[0066] 6A , in the clearance measurement method according to the first embodiment, first, in step ST41 as an acquisition step, the control unit 21 of the clearance measurement device 20 acquires measurement data from the 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 the measurement unit 35 in step ST3.

[0067] (Initial state setting step) Next, the process proceeds to step ST42 as an initial state setting step, in which the clearance calculation unit 211 of the control unit 21 sets the initial state of the male joint 11 and 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 "initial state" refers to a predetermined initial state set by vertical movement and rotation based on thread theory, with the complete joining 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, as shown in Figure 2A. Here, the "complete joining state" refers to a state in which the male fitting 11 is threaded into the female fitting 12 and is no longer able to rotate in the direction in which the threads advance. Ideally, as shown in Figure 2A, this is a so-called shoulder touch state in which the unthreaded portion of the male fitting 11 contacts the tip of the female fitting 12. Note that the vertical movement according to thread theory is a vertical movement of 1 / thread pitch per number of threads (revolutions). The vertical movement from the complete joining state to the initial state is calculated by multiplying the thread pitch by the number of threads (thread pitch × number of threads), and the number of rotations is calculated by multiplying the reciprocal of the multiplier by the number of threads (1 / number of threads (revolutions) × number of threads). The order of the vertical movement and rotation may be any order and is not limited to this. In addition, if the number of threads is the total number of threads, the state will be a separated state just before the start of joining as shown in Figure 2B, but by setting the number of threads to any desired number, it is possible to start the judgment from a semi-joined state.

[0069] Specifically, as shown in FIG. 6B , the control unit 21 acquires the data acquired in step ST41 (see FIG. 6A ) as data for initial setting (step ST411). Next, a state in which the male joint 11 and the female joint 12 are joined, such as that shown in FIG. 2A , is set (step ST412). Next, the process proceeds to step ST413, where vertical movement based on the screw theory is performed. The process also proceeds to step ST414, where rotational movement based on the screw theory is performed. Steps ST413 and ST414 may be performed in reverse order. Alternatively, in step ST415, a state in which the threads of the male joint 11 and the female joint 12 begin to contact each other during joining is set. The process in step ST415 sets the state shown in FIG. 2B in which the threads of the male joint 11 and the female joint 12 begin to contact each other during joining. Since this state is determined to be a single location, it can be set as a predetermined initial state.

[0070] Thereafter, the process proceeds to step ST416, where a predetermined initial state is set based on the processing of steps ST413, ST414, and ST415. Note that only one of the processing of steps ST413, ST414, and ST415 may be executed, or all of the processing may be executed, or only the processing of steps ST413, ST414, and ST415 may be executed. As described above, the control unit 21 vertically and rotationally moves the male joint 11 relative to the female joint 12 to a predetermined position, and sets the so-called loosened state as the predetermined initial state.

[0071] The greatest feature of the present invention is that the completed joining state is used as the reference, and the state in which the male joint 11 is loosened by vertically and rotationally moving the male joint 11 relative to the female joint 12 to a predetermined position based on the above-mentioned screw theory is set as a predetermined initial state, and then clearance measurement begins from this predetermined initial state.

[0072] Typically, when checking a joining using an actual object, the position where the male and female threads mate (the thread start position relative to the circumferential direction of the joint) is identified while moving. Here, in the case of a single-start thread, there is only one thread start position relative to the circumferential direction of the joint, and depending on the conditions of the threaded joint described above, it becomes difficult to identify the initial position that serves as the initial state. In the case of a multiple-start thread, there are multiple thread start positions relative to the circumferential direction of the joint, and if use at a specific start position is expected, it becomes difficult to identify the initial position that serves as the initial state. In particular, when virtually simulating a joining using a computer or the like, multiple conditions can be considered in the circumferential and axial directions for setting the position where the male and female threads mate, making it even more difficult to start screwing the male thread into the female thread.

[0073] 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 or hypothetical cases. Therefore, in the present invention, the joining completion position is used as a reference, and a predetermined initial state is set in which the male joint 11 is vertically and rotationally moved to a predetermined position on the female joint 12 based on the above-mentioned thread theory, thereby loosening the male thread and measuring the clearance while joining the male thread to the female thread. This simplifies the clearance measurement process and makes it possible to measure the clearance more easily regardless of the state of the threaded joint or the connected pipes.

[0074] (Clearance Measurement Step) Next, in step ST43 as a clearance measurement step, the clearance between the male thread 13 and the female thread 14 is derived based on the measurement data. The clearance is derived by the clearance calculation unit 211 of the control unit 21 at a preset location from a predetermined initial state of the male thread 13 and the female thread 14. In this specification, clearance is also referred to as a gap or play.

[0075] Here, Figures 7A, 7B, and 7C show how to create a coordinate system for measurement positions. That is, as shown in Figure 7A, a plane is created to create 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 the cross section line L shown in Figure 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 Figure 7C, a circle (hereinafter referred to as a fit circle) is created that minimizes the error between the curve and the specified point (designated point). A coordinate system is created using the center point of this fit circle and multiple intersection points C. Note that the method of creating a coordinate system described with reference to Figures 7A to 7C is merely an example, and any method can be used to create and set a coordinate system.

[0076] Returning to Figure 6A, based on the coordinate system created in this way, four locations can be selected as the preset locations, each shifted by, for example, 90° around the center of a circle in the cross section (a plane perpendicular to the up-down direction in Figures 1, 2A, and 2B) of the male joint 11 or the female joint 12. Note that the preset locations can also be eight locations shifted by, for example, 45° around the center of the circle, and are not necessarily limited to a specific position or number.

[0077] In step ST43, the clearance calculation unit 211 generates cross-sectional views of the thread from the thread shape data at four or eight predetermined positions, as described above, and derives the clearance c between the male thread 13 and the female thread 14. By setting the method for determining the measurement points as shown in Figures 7A to 7C in this way, the clearance calculation unit 211 can automatically calculate the clearance at the specified positions using a predetermined method. Note that the cross-sectional views 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 the 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.

[0078] 8 and 9 show examples of cross sections of the threaded joint 10 converted into 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 converted data of the threaded joint 10 in a state 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 converted data of the threaded joint 10 in a state in which the male thread 13 and female thread 14 are partially interfering with each other and are not properly joined.

[0079] As shown in Figure 8, when there is no interference between the threads 13a, 14a and the thread roots 13b, 14b, respectively, 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 5.0 mm. The centers of the threads 13a, 14a are defined as the closest points that are half the distance between the corners of the male thread 13. Furthermore, the white dots p are measurement points that 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 dots p there are, the more accurate the determination of the center positions of the male thread 13 and the female thread 14 can be.

[0080] The height h of the threads 13a, 14a is the distance between the center of the threads 13a, 14a and the root on 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 thread 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 thread 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.

[0081] The clearance c is not necessarily limited to the definition described above, and various definitions can be set depending on whether the threaded joint 10 can be joined. For example, as another definition of clearance c, a method of determining the position taking into account the apexes of the threads 13a, 14a can be adopted. That is, when the apexes to be measured are determined in advance and connected at an angle, the distance corresponding to the radial or axial direction between the connected apexes can be measured and used as clearance c. Alternatively, the distance can be measured in the normal direction between each point on the male joint 11 or the line connecting the points, i.e., for each mesh, and the distance when the male joint 11 comes into contact with the female joint 12 in the joined state, i.e., the shortest distance, can be set as clearance c. Conversely, the distance can be measured in the direction from the female joint 12 toward the male joint 11.

[0082] On the other hand, as shown in Figure 9, if interference (interference portion 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 will not be 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 and the threads 13a of the male thread 13 will be, for example, -1 mm, meaning that there will be interference of 1 mm in the radial direction.

[0083] In the examples of Figures 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 single-start male thread 13 to the start of the thread root 13b of the next single-start male thread 13. Alternatively, the thread pitch P is the axial distance from the end of the thread 14a of a single-start female thread 14 to the start of the thread 14a of the next single-start female thread 14. In the case of a single-start thread, the thread pitch P refers to the distance the thread advances per rotation. On the other hand, in the case of a multiple-start thread, the distance advanced per rotation varies depending on the number of threads on the thread, making it difficult to define the thread pitch P as a fixed distance. Therefore, although the thread pitch P is defined as described above in this specification, it is not necessarily limited to the above definition.

[0084] The clearance calculation unit 211 stores the clearance c calculated at multiple predetermined locations, for example, four or eight locations, as clearance information in the clearance database 221. The clearance c is calculated for all threads 13a, 14a and thread roots 13b, 14b of the joined portions of the male joint 11 and the female joint 12 at multiple predetermined locations. The minimum clearance c in the radial direction relative to the rotation axis is then calculated. Specifically, the clearance calculation unit 211 uses predetermined measurement software to extract the minimum value of the clearance c between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12 in the radial direction relative to the rotation axis in each longitudinal cross section (see FIG. 7B ). The calculated clearance c information may be associated with the threaded joint identification ID of the pipe type information stored in the pipe type database 222 and stored in the memory unit 22.

[0085] (Clearance Determination Step) Next, the process proceeds to step ST44 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 less than a predetermined value. Note that the predetermined value can be set to any value, and in this embodiment, the predetermined value is set to 0, for example.

[0086] If the determination unit 212 determines in step ST44 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 less than a predetermined value, specifically, for example, less than or equal to 0 (c≦0) (step ST44: Yes), the process proceeds to step ST48. In step ST48, the determination unit 212 outputs information that the threaded joint 10 being measured has failed, and stores this failure information as clearance information in the clearance database 221. This completes the clearance measurement process.

[0087] If the determination unit 212 determines in step ST44 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, greater than 0 (c > 0) (step ST44: No), the process proceeds to step ST45. That is, if the clearance c at the joint portions at multiple predetermined locations is greater than a predetermined value, it is determined that no interference occurs and that 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 that the male joint 11 and the female joint 12 are joinable if the clearance c is always positive (c = r2 - r1 > 0). Note that 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 at locations other than the threaded portion, and therefore a similar determination may be made. However, because radial deformation of the threaded joint 10 is most likely to occur in the threads, the judgment unit 212 can judge that joining is possible if the radial clearance of the threaded joint satisfies the above-mentioned condition (c > predetermined value). Note that, in this static study, a method was adopted in which measurement software and CAD were used to assume that the overall shape of the joint is rigid and does not deform. However, a dynamic study can also be adopted that takes into account factors such as elastic deformation of the joint shape due to minute partial interference and frictional resistance. In the dynamic study, dynamic analysis is performed using FEM or mechanism analysis, and interference is judged based on fluctuations in load, torque, contact, friction, etc.

[0088] (Joining Determination Step) In step ST45 as a joining determination step, the determination unit 212 determines whether or not joining is complete between the male joint 11 and the female joint 12 in the threaded joint 10. If the determination unit 212 determines that joining is complete between the male joint 11 and the female joint 12 (step ST45: Yes), the process proceeds to step ST47.

[0089] In step ST47, the determination unit 212 outputs information that the threaded joint 10 being measured passes, 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.

[0090] On the other hand, if the determination unit 212 determines in step ST45 that the male joint 11 and the female joint 12 have not rotated to the predetermined position and the joining is not completed (step ST45: No), the process proceeds to step ST46.

[0091] (Rotational State Setting Step) In step ST46 as a rotational state setting step, the clearance calculation unit 211 sets a state in which the joined male joint 11 and female joint 12 are rotated in a rotational direction that advances in the joining direction by a predetermined rotation angle, specifically, for example, 90° or 45°. Here, the rotational state setting step executed in step ST46 will be described in detail.

[0092] That is, the data-stored male joint 11 and female joint 12 are rotated from their initial state in the direction of rotation during joining to complete the joining. When virtually joining is performed using this data, if no interference occurs at all cross sections in all threaded portions of the male thread 13 and female thread 14, it can be determined that the male joint 11 and female joint 12 are joinable. Conversely, if interference occurs at least in part, i.e., if the clearance c is equal to or less than a predetermined value, it can be determined that joining is impossible.

[0093] As described above, it is preferable to first set a predetermined initial state of the male joint 11 and the female joint 12 and then perform the determination by starting rotation in the joining direction, which is an important feature of the present embodiment. When deriving the degree of interference while rotating the male thread 13 and the female thread 14 in the joining direction from a joining start state in which the male joint 11 and the female joint 12 are separated in the threaded joint 10, if the rotational joining is simply started from a position where the male joint 11 and the female joint 12 are in contact, it is impossible to confirm whether the position where the rotational joining is finally completed can be reached without continuing the rotation. In this case, it becomes necessary to repeatedly change the positions of the male joint 11 and the female joint 12 to search for a position where the rotational joining is actually completed. In contrast, when rotating from a predetermined initial state based on 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, and therefore the position search can be omitted. Here, when checking the joining of an actual threaded joint 10 rather than a digitalized version, it is possible to identify the initial position for starting the joining while moving it. When checking the joining virtually on a digitalized virtual system, it is necessary to consider and search for multiple initial state settings, i.e., the initial position for starting the joining, in the circumferential direction, the axial direction, etc., and it is extremely difficult to rotationally join the male joint 11 and the female joint 12 using virtual data. In contrast, it is relatively easy to identify the joining completion position. This simplifies and improves the efficiency of the measurement process for the threaded joint 10 by using the joining completion state as a reference and vertically and rotationally moving the male joint 11 to a predetermined position on the female joint 12 based on the above-mentioned thread theory to set the loosened state as a predetermined initial state, and then rotating the male joint 11 to join the female joint 12 while checking for interference.

[0094] Next, a specific procedure executed by the clearance calculation unit 211 in step ST46 will be described. First, as shown in Figures 2A and 2B, the male joint 11 and female joint 12 converted into data are virtually placed at the initial positions set in step ST42.

[0095] To do this, first, the rotation axes of the male joint 11 and the female joint 12 are extracted. Specifically, for example, the outer diameter of the tip of the male joint 11 and the inner diameter of the tip of the female joint 12 are selected at multiple points, such as four or eight points.

[0096] Next, a fitting circle that minimizes the deviation from the selected point is created, and the center of the fitting circle is set as the rotation axis.

[0097] The rotation axes of the male joint 11 and the female joint 12 are aligned, and the state of shoulder touch is derived by aligning with the position of the eye mark (the position and angle of the rotation axis are fine-tuned so that the shoulder distance is within a set value at multiple cross sections, such as four or eight points). This state is the joining completion position. Note that any method can be used to set the rotation axis and joining completion position, and various methods other than the method described above can be used.

[0098] Next, using the completed joining state where the rotation axes of the male joint 11 and the female joint 12 are aligned and shoulder-touched as a reference, vertical movement and rotation are performed based on screw theory (vertical movement by the thread pitch per (1 / number of threads) rotation) to set a predetermined initial state.

[0099] In this state, the minimum clearance along the radial direction of the rotation axis is calculated for all threads 13a, 14a in longitudinal sections at predetermined angular intervals, such as 45° or 90° (see FIGS. 7A to 7C). Negative clearances are also measured. The minimum clearance value in the radial direction of the rotation axis for the threaded portions of the male joint 11 and the female joint 12 in each longitudinal section is extracted using measurement software. More specifically, the overall minimum value is calculated, or the minimum value is calculated for each of multiple threads of the threads 13a, 14a. Furthermore, depending on the conditions, visual inspection or examination using representative points is also possible. Alternatively, the distance may be measured in the normal direction of each point or line connecting points, i.e., each mesh, on the male joint 11, and the distance when the male joint 11 comes into contact with the female joint 12 in the joined state, i.e., the shortest distance, may be set as clearance c. Conversely, the distance may be measured in the direction from the female joint 12 toward the male joint 11.

[0100] Thereafter, the threads are rotated in the joining direction by a predetermined rotation angle. Here, the rotation angle may be, for example, at 45° intervals or 90° intervals, but is not limited thereto. The amount of axial movement corresponding to the angle of 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 rotation interval are set to 45° or less or 90° or less because the threaded joint 10 is continuous in the circumferential direction, which makes it difficult for local deformation to occur, and the presence or absence of interference can be sufficiently detected even when checking at intervals of approximately 45° to 90°.

[0101] If interference occurs during rotation, the rotation axis of the male joint 11 is moved to a position with a larger clearance along the radial direction of the rotation axis, and the presence or absence of interference is confirmed at that stage. If further interference occurs, the rotation axes of the male joint 11 and the female joint 12 are moved along the axial direction to search for a position where no interference occurs. If further interference occurs, the angle of the rotation axis is adjusted as necessary to search for a position where no interference occurs. Once a position where no interference occurs is identified, rotation is restarted from that position. Note that the order of movement of the rotation axis is not limited to the above procedure and can be performed in any order. It is also possible to determine the presence or absence of interference by setting an appropriate reference value without moving the rotation axis. Furthermore, by comparing the clearance between the target cross section and a cross section at a 180-degree symmetrical position with the determination criterion, it is possible to make a determination without actually moving the rotation axis.

[0102] The above procedure is repeated until the male joint 11 and the female joint 12 are rotated and joined. 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 joined, and if it is less than the predetermined value, it is determined that they cannot be joined.

[0103] After the rotational state setting step in step ST46 is completed, the process proceeds to step ST43, where the clearance c of the joined portion at a predetermined location is derived. The control unit 21 repeatedly executes steps ST43 to ST46 until the clearance c becomes equal to or less than a predetermined value (step ST44: Yes) or until the joining of the male joint 11 and the female joint 12 is completed (step ST45: Yes). The determination unit 212 then stores pass / fail information for the threaded joint 10 being 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, a failure determination is made when the clearance c becomes equal to or less than a predetermined value, thereby shortening the time required to determine whether the threaded joint 10 is a failed product.

[0104] Thereafter, the process proceeds to step ST5 shown in Figure 5, where the control unit 21 outputs pass or fail information for the threaded joint 10 being measured to the input / output unit 23. Note that for threaded joints 10 that have been judged to have failed, a mark may be placed on the actual threaded joint 10. Note that for threaded joints 10 that have been judged to have failed, it is possible to appropriately select whether to perform the adjustment process described below or to discard the threaded joint. This completes the measurement process for the threaded joint.

[0105] The quality of the threaded joint 10 can be controlled based on the threaded joint measurement method described above.

[0106] That is, in the quality control method for a threaded joint 10, first, the threaded joint 10 is manufactured in 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 in a joint measurement process in step ST3.

[0107] Thereafter, in step ST4, the measurement results obtained in the joint measurement process are used to measure the clearance, thereby making it possible to control the quality of the threaded joint 10 as a quality control process.

[0108] (First Modification) Next, a first modification of the clearance measurement process according to the first embodiment described above will be described. Figure 10 is a flowchart for explaining the clearance measurement process according to the first modification. In the clearance measurement method according to the first embodiment, the clearance measurement process is completed when a location where the clearance is equal to or less than a predetermined value is found. In contrast, the clearance measurement process according to the first modification differs from the clearance measurement process according to the first embodiment in that it is assumed that the entire circumferences of the male joint 11 and the female joint 12 of the threaded joint 10 are measured, regardless of whether the clearance measurement passes or fails.

[0109] That is, as shown in FIG. 10 , steps ST421 to ST423 are respectively the same as steps ST41 to ST43 in the first embodiment described above. In the first modified example, after step ST423 is executed, the process proceeds to step ST424. In step ST424, clearance calculation unit 211 stores the results of clearance c derived at a plurality of preset locations, for example, four or eight locations, as clearance information in clearance database 221. Thereafter, the process proceeds to step ST425. Steps ST425 and ST426 are respectively the same as steps ST45 and ST46 in the first embodiment. Furthermore, in the first modified example, the process of determining whether 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, their explanations are omitted.

[0110] (Second Modification) Next, a second modification of the clearance measurement process according to the first embodiment will be described. Figure 11 is a flowchart for explaining the clearance measurement process according to the second modification. In the clearance measurement method according to the first embodiment, the clearance measurement process is completed when a location where the clearance is equal to or less than a predetermined value is found. In contrast, the clearance measurement process according to the second modification differs from the clearance measurement process according to the first embodiment in that the clearance is measured over the entire circumference of the male joint 11 and the female joint 12 of the threaded joint 10, regardless of whether the clearance is equal to or less than the predetermined value, and then a determination is made based on a comparison with the predetermined value.

[0111] 11, steps ST431 to ST434 are respectively the same as steps ST421 to ST424 in the first modified example described above. In the second modified example, after step ST434 is executed, the process proceeds to step ST435. In step ST435, clearance calculation unit 211 executes step ST435, which is a rotation state setting step similar to step ST46 in the first embodiment. The process proceeds to step ST436.

[0112] In step ST436, the determination unit 212 determines whether or not the joining is completed in the same manner as in step ST45.

[0113] If the determination unit 212 determines in step ST436 that joining of the threaded joint 10 is not complete (step ST436: No), the process proceeds to step ST433, and steps ST433 to ST436 are repeatedly executed.

[0114] If the determination unit 212 determines in step ST436 that joining of the threaded joint 10 has been completed (step ST436: Yes), the process proceeds to step ST437.

[0115] In step ST437, the determination unit 212 determines whether the clearance c between the male joint 11 and the female joint 12 is equal to or less than a predetermined value, similar to step ST44 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, which serves as an interference information assignment step. In step ST438, which serves as an interference information assignment step, the determination unit 212 flags the portion where the clearance c is equal to or less than the predetermined value as an interference portion. Next, the determination unit 212 stores the flag related to the interference portion as clearance information in the clearance database 221 of the storage unit 22. This completes the clearance measurement process.

[0116] The clearance measurement process according to the first and second modifications can be used when it is desired to set the clearance at the manufacturing site or when there is little need to obtain the clearance determination result in real time or in a short time. In particular, the clearance measurement process according to the second modification 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 portions where the clearance is equal to or less than the predetermined value. This makes it easier to handle cases where the clearance measurement process is performed at a location other than the manufacturing site.

[0117] The above-described method for measuring a threaded joint 10 according to the first embodiment of the present invention allows confirmation of whether the threaded joint 10 can be joined after its manufacture is complete or before its construction. While conventional methods rely on whether the male joint 11 and the female joint 12 can rotate, this method ensures accuracy by confirming the interference between the threads 13a and 14a as clearance between the threads using information based on the measurement results. Furthermore, because the method starts from a predetermined initial state based on the completed joining state of the threaded joint 10, there is no need to search for the starting position for joining. Furthermore, interference points can be detected early, allowing for efficient start of measurement of the clearance of the threaded joint 10. Furthermore, regardless of the condition of the threads, such as the outer diameter, length, and weight, this method allows for safe and simplified pre-joining confirmation at a factory or other on-site location. The method for measuring a threaded joint 10 according to this embodiment can be used not only in factories but also in storage areas at construction sites. 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 female joint 12 can be measured using 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 need for on-site work to be stopped due to problems.

[0118] Second Embodiment Next, a method of measuring a threaded joint according to a second embodiment of the present invention will be described. Figure 12 is a flowchart for describing a method of measuring a threaded joint 10 according to the second embodiment. In the method of measuring a threaded joint 10 according to the second embodiment, the clearance c is determined around the entire thread circumference of the threads 13a, 14a in the male joint 11 and the female joint 12, and then a pass / fail determination is made for each threaded joint 10. Also, unlike the first embodiment, step ST44 (see Figure 6A) as a clearance determination step is separated from the clearance measurement step (step ST4).

[0119] 12, in the measurement method for a threaded joint 10 according to the second embodiment, steps ST1 to ST4 are performed in the same manner as in the first embodiment. Thereafter, a pass / fail determination step is performed in step ST6 instead of step ST5 according to the first embodiment. 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.

[0120] 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 for 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. Various criteria can be used as the pass / fail determination criteria of the determination unit 212. A method similar to that used in step ST44 (see FIG. 6A ) 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. If the locations where the clearance c is equal to or less than a predetermined value, i.e., 0 or less, are considered to be interference locations, it is possible to determine whether the number of locations where the clearance c is equal to or less than a predetermined number is a fail, and otherwise a pass. Alternatively, a determination may be made such that if there is even one location where the clearance c is 0 or less or a location flagged as an interference location, the result is a failure, and if there are no such locations, the result is a pass. That is, in the clearance measurement process according to the third modified example, it is possible to determine pass or fail based on the number of locations where the clearance c is equal to or less than a predetermined value or the number of flags indicating interference locations.

[0121] Furthermore, in the pass / fail determination step, similar to step ST438 in the second modified example, not only is the pass / fail of the threaded joint 10 determined, but also, based on the measured clearance c contained in the clearance information, any locations where the clearance c is equal to or less than a predetermined value may be flagged as interference locations. In this case, it is possible to determine, for example, that the joint is failed if the number of flags is equal to or greater than a predetermined number, and passed if the number is less than the predetermined number.

[0122] If the threaded joint 10 is judged to be pass in the pass / fail determination process (step ST6: Yes), the process proceeds to step ST61, where the fact that the threaded joint 10 is pass is output to the input / output unit 23, etc., or can be 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. On the other hand, if the threaded joint 10 is judged to be pass in the pass / fail determination process (step ST6: NO), the process proceeds to step ST62. A threaded joint 10 that has been judged to be fail can be discarded or readjusted. In this case, if necessary, the clearance information for the target threaded joint 10 can be associated with the identification ID of the threaded joint and transmitted to the thread machining device 40, 40A.

[0123] 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 a pass / fail determination using an external processing device via the network 2, and to share information on the inspection results of the threaded joint 10.

[0124] (Third embodiment) Next, a method of measuring a threaded joint according to a third embodiment of the present invention will be described. Figure 13 is a flowchart for explaining a method of measuring a threaded joint 10 according to the third embodiment. The method of measuring a threaded joint 10 according to the third embodiment differs from the first embodiment in that an adjustment step is carried out after the clearance measurement step in step ST4.

[0125] 13, in the measurement method for a threaded joint 10 according to the third embodiment, steps ST1 to ST4 are performed in the same manner as in the first embodiment. Thereafter, an adjustment step is performed in step ST7 instead of step ST5 according to the first embodiment. Furthermore, in the third embodiment, the clearance measurement step according to the first embodiment, the first modified example, or the second modified example can be used as the clearance measurement step in step ST4.

[0126] (Adjustment Process) Next, the adjustment process in step ST7 will be described. As shown in Figure 13, the adjustment process is carried out after the clearance measurement process for a threaded joint 10 that has been determined to be unacceptable or to have an interference location based on the measured clearance c. The adjustment process includes adjustment steps, which will be described later. Note that if, for example, pass or fail information is not output in the clearance measurement process, which is carried out in the preceding stage, step ST6 (pass / fail determination process) according to the second embodiment may be carried out before each of the adjustment steps, which will be described later, in step ST7.

[0127] (Adjustment Step) In step ST7, the adjustment process for the threaded joint 10, the shape measurement process, clearance measurement process, and adjustment process can be repeatedly performed until the set of threaded joints 10 that require adjustment is determined to be acceptable. Furthermore, within the adjustment process, a pass / fail determination process can be performed before the adjustment step. As the adjustment step, an appropriate method can be selected and adopted, for example, from the methods described above, depending on the specifications and purpose of the threaded joint 10.

[0128] That is, the first method in the adjustment step is a method in which, when there are multiple welding start positions for the threaded joint 10, such as when the threaded joint 10 is configured with a multiple-start thread, the welding start position is virtually changed and a pass / fail judgment step is performed by the judgment unit 212 to make a pass / fail judgment. Here, when the pass / fail judgment step is passed, the completion and start positions are marked at positions corresponding to the actual position.

[0129] Next, the second method in the adjustment step is to virtually cut a portion of the threaded joint 10 within a range that satisfies the proof stress required for the male joint 11 and the female joint 12, and then perform the pass / fail determination process again on the threaded joint 10 whose thread shape has been modified, to determine whether it passes or fails. If the interference is small, it is possible to consider cutting within a safety factor of, for example, about 1.2, and then perform cutting on the actual part using a grinder or the like once the virtual part passes. The first and second methods described above do not require another 3D scanning operation by the measurement unit 35.

[0130] Next, the third method in the adjustment step is a method in which a portion of the actual threaded joint is corrected by correction due to thermal deformation, measurement is performed again using the measurement unit 35, and the pass / fail determination process is carried out again to determine whether the joint passes or fails. Note that correction due to thermal deformation is performed by welding heat or burner heating, and, if necessary, compression or tension using a jack.

[0131] Next, a fourth method in the adjustment step is to manufacture a new threaded joint 10, measure it again using 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 manufacturing, but also includes, in the case of a steel pipe with a joint, removing the threaded joint 10 from the pipe 15, 16 and reattaching it. Note that if 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.

[0132] 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.

[0133] (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 employed as the threaded joint measurement system, and the clearance measurement process according to the first embodiment is employed. 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.

[0134] Here, the control unit 31 of the measurement terminal 30A can output the clearance information transmitted from the clearance measurement device 20A, for example by displaying it on the input / output unit 33. Note that the clearance information displayed on the input / output unit 33 can include various types of information such as the pass / fail result of the threaded joint 10 and an enlarged display of a cross-sectional view of the interference point between the male thread 13 of the male joint 11 and the female thread 14 of the female joint 12.

[0135] Furthermore, the control unit 31 can select various pieces of information received from the clearance measurement device 20A via the network 2 and output the selected information from the input / output unit 33. For example, even when 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 perform control so that a failure is output from the input / output unit 33 only when a fail result 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 and correct the location of interference.

[0136] Fifth Embodiment Next, a fifth embodiment will be described. In the fifth embodiment, a threaded joint measurement system 1A according to the second example of the embodiment is employed as the threaded joint measurement system. Furthermore, a threaded joint measurement method according to the second embodiment shown in FIG. 12 is employed as the threaded joint 10 measurement method. In this case, it is preferable to employ the clearance measurement process according to the first or second modified example. In the fifth embodiment, the clearance measurement device 20 can be configured as a fixed information processing device, or can be configured as a server capable of communicating with the measurement terminal via the network 2. In this case, the measurement terminal 30A is configured as an independent terminal capable of communicating with the clearance measurement device 20 via the communication unit 34 and the network 2.

[0137] In the fifth embodiment, control unit 31 of measurement terminal 30A has the same function as 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.

[0138] In the fourth and fifth embodiments, the measurement terminal 30A can be used independently, making it possible to measure the threaded joint 10 and determine whether it passes or fails at various work sites.

[0139] Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical concepts of the present invention are possible. For example, the numerical values ​​and materials given in the above-described embodiments are merely examples, and different numerical values ​​and materials may be used as necessary.

[0140] For example, in each of the above-described 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, the "Yes" and "No" in step ST44 and step ST437 may be interchanged based on whether the clearance c is equal to or greater than a predetermined value as the predetermined criterion. Even in these cases, the predetermined value can be set to a value greater than or equal to 0.

[0141] For example, the threaded joint measurement method 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 ST43 to ST46 and steps ST423 to ST426 described above can be performed using a software program by the control unit 21 of the clearance measurement device 20. This makes it possible to achieve even greater efficiency in the threaded joint measurement method.

[0142] The present invention is suitably applied to a pipe joint structure for joining pipes.

[0143] DESCRIPTION OF SYMBOLS 1, 1A Threaded joint measurement system 2 Network 10 Threaded joint 11 Male joint 12 Female joint 13 Male thread 13a, 14a Thread 13b, 14b Thread root 14 Female thread 15 Pipe 20, 20A Clearance measurement device 21, 31, 41 Control unit 22, 32, 42 Memory unit 23, 33, 43 Input / output unit 24, 34, 44 Communication unit 30A Measurement terminal 35 Measurement unit 40, 40A Thread processing device 45 Thread processing unit 211 Clearance calculation unit 212 Determination unit 221 Clearance database 222 Pipe type database 311 Measurement control unit 411 Processing control unit

Claims

1. A clearance measurement method for measuring 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, comprising: an initial state setting step for setting an initial state of the male joint and the female joint based on data on the thread shapes of the male joint and the female joint, respectively; a clearance measurement step for measuring 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 initial state; and a rotational state setting step for, if joining of the male joint and the female joint has not been completed after the clearance measurement step, setting a state in which the male joint and the female joint have been rotated a predetermined angle in the direction in which the joining will be performed, and the steps from the clearance measurement step to the rotational state setting step are repeatedly executed until the joining is completed.

2. A clearance measurement method according to claim 1, comprising at least one of the following steps: 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 standard; and an interference information assignment step of assigning information about an interference location to a location that has been determined to be an interference location based on the clearance measured in the clearance measurement step and a predetermined standard.

3. A method for measuring a threaded joint, comprising: a shape measurement step of measuring the thread shape of a male joint and a female joint corresponding to the male joint, respectively, for a set of threaded joints having the male joint and the female joint; and a clearance measurement step of measuring the clearance for each set of threaded joints by the clearance measurement method described in claim 1 or 2, based on data on the thread shape measured in the shape measurement step.

4. A method for manufacturing a threaded joint for manufacturing a set of threaded joints having a male joint and a female joint corresponding to the male joint, comprising: a joint manufacturing process for manufacturing a threaded joint; and a joint measurement process for carrying out the threaded joint measurement method described in claim 3 on the set of threaded joints having a male joint and a female joint produced by the joint manufacturing process.

5. 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 that corresponds to the male joint, 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 using the threaded joint measurement method described in claim 3; and a quality control process for controlling the quality of the produced threaded joint using the results obtained from the joint measurement process.

6. A clearance measurement device that measures the clearance between the threads of a male joint and a female joint corresponding to the male joint for a set of threaded joints having the male joint and the female joint, comprising: a joining completion state setting process that sets a joining completion state in which joining of the male joint and the female joint is complete, based on data on the thread shapes of the male joint and the female joint, respectively; and a rotation state setting process that sets a state in which the male joint and the female joint are rotated by a predetermined angle in the direction in which the joining is to be performed, if the joining of the male joint and the female joint is not complete in the joining completion state after the clearance between the threads of the male joint and the threads of the female joint corresponding to the threads of the male joint has been measured. The clearance measurement device comprises a control unit that repeatedly executes these processes until the joining is completed.

7. The clearance measurement device according to claim 6, wherein the control unit executes a clearance measurement process 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 initial state before the rotation state setting process.

8. The clearance measurement device according to claim 6, further comprising a communication unit, wherein the communication unit executes, via the control unit, at least one of a process for acquiring data on the thread shapes of the male joint and the female joint, and a process for outputting information relating to the clearance obtained by the clearance measurement process.

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

10. A measurement terminal controlled by a control unit, configured to be able to measure 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, the measurement terminal comprising: 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, under the control of the control unit, executes at least one of an output process that outputs the measured thread shape as data to a clearance measurement device described in any one of claims 6 to 8, and an acquisition process that acquires information regarding the clearance for each set of threaded joints from the clearance measurement device; and an output unit that, under the control of the control unit, is able to output the acquired information in a predetermined format.

11. The measurement terminal according to claim 10, wherein the control unit executes at least one of the following processes: a process for determining whether the set of threaded joints is pass or fail based on the acquired information on the clearance and a predetermined standard; and an interference information assignment process for assigning information on the interference location to a location determined to be an interference location based on the acquired information on the clearance and a predetermined standard.

12. A threaded joint measurement system comprising: the measurement terminal according to claim 10; and the clearance measurement device according to any one of claims 6 to 8, which measures the clearance for each set of threaded joints based on data on the thread shape measured by said measurement terminal.

13. A quality control method for threaded joints that controls the quality of a set of threaded joints having a male joint and a female joint that corresponds to said male joint, wherein the quality of the set of threaded joints is controlled using information about the clearance obtained from a clearance measurement process executed by the control unit of a clearance measurement device described in any one of claims 6 to 8.

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