Flange fastening skill determination apparatus and flange fastening skill determination program

Abstract

This flange-fastening skill determination device is equipped with: a reception unit for receiving, from fastening force detectors individually corresponding to each of a plurality of bolts to be fastened in order to connect flanges together, output signals that are output in association with tightening of the plurality of bolts by an examinee; a measurement unit for obtaining a plurality of measurement results that indicate transitions of changes in each output signal received by the reception unit between the respective tightening start times and the tightening end times for the plurality of bolts; a computation unit for performing computations on the plurality of measurement results in order to obtain, as skill determination items, a first computation result that indicates variation in the values of the output signals from the fastening force detectors during the tightening of the plurality of bolts, a second computation result that indicates variation in the values of the output signals from the fastening force detectors at the time of the completion of the tightening of the plurality of bolts, and a third computation result that indicates the intensities of the tightening forces at the time of the completion of the tightening of the plurality of bolts; a determination unit for determining which one of three or more skill levels an examinee performing the bolt tightening work has on the basis of a matching result between the determination items and determination criteria; and an output unit for outputting the determination result generated by the determination unit.

Description

The present invention relates to a flange fastening skill determination device and a flange fastening skill determination program. In production plants and other industrial settings, for example, pipes are connected by butting the flanges of a pair of pipes together with a gasket and then tightening multiple bolts. This bolting of flanges is generally done manually by workers. To maintain a stable connection between pipes over the long term and prevent pipe leaks (flange leak problems), it is important to properly tighten each bolt on the flanges of a pair of pipes and to check the tightening status of each bolt during maintenance and scheduled repair work. For this reason, for example, Patent Documents 1 and 2 disclose a configuration in which electrodes or pressure sensors are placed on a gasket between a pair of flanges to monitor the tightening status of each bolt fastening the flanges. Patent No. 4699935 Publication JP-A-9-329281 If the bolts fastening the flanges of a pair of pipes are not tightened properly, problems can arise in the continued operation of the equipment and plant, such as leaks occurring after only a few heat cycles. Furthermore, in periodic maintenance work on petrochemical plants, the number of pipe flanges fastened with bolts can reach over a thousand, making it difficult to inspect the tightening condition of each bolt on each flange. Therefore, in order to prevent flange fastening defects and obtain proper flange fastening conditions, it would be useful to be able to determine in advance the skill (skill) of the worker regarding flange fastening before performing the bolt tightening work, in order to appropriately select personnel to obtain high-quality work. In this regard, the aforementioned Patent Documents 1 and 2 only disclose a configuration for monitoring the tightening condition of bolts after fastening and a configuration for measuring the tightening force of bolts after flange fastening, and do not envision determining the worker's skill regarding bolt tightening in advance. The present invention has been made in view of the above problems, and aims to provide a flange fastening skill determination device and a flange fastening skill determination program that can objectively and clearly determine the skill of a worker in the process of fastening flanges. To solve the above problems, a flange fastening skill determination device according to one aspect of the present invention includes: a receiving unit that receives output signals output by a subject in conjunction with the tightening work of a plurality of bolts that are tightened to connect a flange from each tightening force detector provided to correspond to each bolt individually; a measuring unit that obtains a plurality of measurement results received by the receiving unit, showing the changes in each of the output signals from the start to the completion of the tightening work for each of the plurality of bolts; a calculation unit that calculates the plurality of measurement results to obtain a first calculation result showing the variation in the output signal values ​​of each of the tightening force detectors during the tightening work of the plurality of bolts, a second calculation result showing the variation in the output signal values ​​of each of the tightening force detectors at the completion of the tightening work of the plurality of bolts, and a third calculation result showing the degree of each tightening force at the completion of the tightening work of the plurality of bolts, each as a skill determination item; a determination unit that determines which of three or more skill levels the subject's skill in tightening each of the bolts is at based on the result of comparing each of the skill determination items with a determination criterion; and an output unit that outputs the determination result from the determination unit. Furthermore, a flange fastening skill determination program according to one aspect of the present invention includes a calculation step in which the computer executes the following steps: a calculation step in which the computer executes the computer to determine which of three or more skill levels the subject's skill in fastening the bolts is output from each tightening force detector provided to correspond to each of the bolts fastened to connect the flanges, and a calculation step in which the computer executes the computer to determine which of the following skill levels the subject's skill in fastening the bolts is, and the computer executes the computer to determine which of the following skill levels the subject's skill in fastening the bolts is, based on the results of comparing each of the skill determination items with the determination criteria: a calculation step in which the computer executes the computer to determine which of three or more skill levels the subject's skill in fastening the bolts is, and an output step in which the computer executes the computer to determine which of the following skill levels the subject's skill in fastening the bolts is, based on the results of comparing each of the skill determination items with the determination criteria: a calculation step in which the computer executes the computer to determine which of the following skill levels the subject's skill in fastening the bolts is, and an output In the flange fastening skill determination device or the flange fastening skill determination program in each aspect of the present invention, a measurement result showing the transition of the change in the output signal of the tightening force detector from the start of tightening to the completion of the tightening operation of each bolt tightened to connect the flanges is obtained, and a plurality of the measurement results are calculated to obtain a predetermined calculation result. Therefore, the calculation result shows the transition of the change over time of the tightening force during the tightening operation of each bolt. Here, by using, as a skill determination item, a first calculation result indicating the variation in the output signal values of each of the tightening force detectors during the tightening operation of the plurality of bolts, it is possible to evaluate whether problems such as so-called flange rotation (defects due to local surface pressure concentration of the gasket), which may occur due to defective tightening work, can occur. Also, by using, as a skill determination item, a second calculation result indicating the variation in the output signal values of each of the tightening force detectors when the tightening operation of the plurality of bolts is completed, it is possible to evaluate whether problems such as so-called single tightening of bolts can occur. Furthermore, by using, as a skill determination item, a third calculation result indicating the degree of each tightening force when the tightening operation of the plurality of bolts is completed, it is possible to evaluate whether the bolts can be tightened with an appropriate tightening force. By using each of these skill determination items to determine which of three or more skill levels the skill of the subject related to the bolt tightening operation is, it becomes possible to evaluate the bolt tightening operation itself, which has been difficult to evaluate conventionally. Therefore, not only the evaluation of whether the tightening force of the bolt after tightening is appropriate is performed, but also the skill of the subject's bolt tightening operation can be objectively and clearly evaluated regardless of the experience and intuition of the subject. As a result, it is possible to appropriately select the most suitable personnel for the bolt tightening operation. Furthermore, by comparing each of the aforementioned skill assessment items with the assessment criteria, the system determines which of three or more skill levels the subject's bolt tightening skills fall into, and outputs the assessment result. This allows for a quick and clear evaluation not only of whether the subject's bolt tightening skills pass or fail the predetermined assessment criteria, but also of the specific level of the subject's bolt tightening skills. As a result, the flange fastening skill determination device or flange fastening skill determination program in each of the above embodiments of the present invention can provide a flange fastening skill determination device and a flange fastening skill determination program that can objectively and clearly determine the skills of an operator in fastening flanges. This is a schematic diagram showing the configuration of the flange bolt fastening skill determination device according to Embodiment 1. This is a functional block diagram showing the configuration of the flange fastening skill determination device. This is an overall flowchart of the operation of the flange fastening skill determination device by the flange fastening skill determination program. This is a flowchart of the determination step. This is a diagram showing the display content (determination screen) of the display unit in the output step. This is a diagram showing the display content (graph determination screen) of the display unit in the output step. This is a diagram showing the display content of the display unit according to Embodiment 2. This is a diagram showing the display content of the display unit according to Embodiment 3. Hereinafter, embodiments of the present invention will be described with reference to the figures. <Embodiment 1> [Configuration of Flange Fastening Skill Determination Device 1] Figures 1 and 2 show a flange fastening skill determination device 1 according to Embodiment 1 (hereinafter referred to as "determination device 1"). The determination device 1 comprises a dummy flange 2, a plurality of bolts 3 with tightening force detectors attached to the dummy flange 2 (hereinafter referred to as "bolts 3"), a receiving unit 4 to which wiring extending from the bolts 3 is connected, a personal computer 5 (hereinafter referred to as "PC 5") connected to the receiving unit 4, and a display unit 6 and input means 7 connected to the PC 5. The dummy flange 2 has a shape and structure that mimics the end of an actual pipe. Here, as an example, the dummy flange 2 has a pair of annular flanges. Each flange has a constant face width and multiple (e.g., eight) through holes are formed at equal intervals in the circumferential direction. The flanges are positioned opposite each other with a gasket (not shown) in between. Bolt 3 has a tightening force detector (not shown) embedded in its shaft. This tightening force detector is configured, for example, using a known temperature-compensated three-wire strain gauge. When the strain gauge is energized, its electrical resistance is output as an output signal. As the strain gauge deforms due to the tightening of bolt 3, the electrical resistance of the strain gauge changes, and the output signal of the strain gauge changes. The judgment device 1 uses multiple bolts 3 (for example, eight bolts 3a to 3h). Each bolt 3 is inserted into each insertion hole of each flange in the dummy flange 2. As part of the flange fastening work for the judgment test, the subject screws a nut onto each bolt 3 and tightens each set of bolts 3 and nuts with a spanner S. This fastens the pair of annular flanges of the dummy flange 2 with a gasket in between. Hereinafter, tightening one set of bolts 3 and nuts will simply be referred to as "tightening the bolts 3". In the determination device 1, a strain gauge embedded in the bolt 3 detects the axial strain of the bolt 3. During the flange fastening process, the bolt 3 is deformed axially due to the repulsive force of the gasket sandwiched between the pair of annular flanges in the dummy flange 2. In other words, the output signal of the strain gauge (the strain detected by the strain gauge) corresponds to the tightening force of the bolt 3 and nut (surface pressure on the flange fastening surface). The receiving unit 4 is connected to the wiring extending from the strain gauges of each bolt 3, and receives the output signals output from each strain gauge in conjunction with the tightening of each bolt 3. The receiving unit 4 is configured, for example, with a known data acquisition interface (DAQ), and performs AD conversion on the received output signals from the strain gauges of each bolt 3 and transmits them to the PC 5. PC 5 ​​is connected to the receiving unit 4 and acquires received signals from the strain gauges of each bolt 3 after AD conversion from the receiving unit 4. PC 5 is an example of a general-purpose computer and, as shown in Figure 2, comprises a processing unit 50 connected to the receiving unit 4, the display unit 6, and the input means 7, and a storage unit 51 accessible by the processing unit 50. The processing unit 50 includes the CPU in PC 5. As shown in Figure 2, the processing unit 50 functionally has a measurement unit 50a, an arithmetic unit 50b, and a determination unit 50c. The storage unit 51 is configured using, for example, a hard disk or non-volatile memory. The storage unit 51 stores a predetermined flange fastening skill determination program (hereinafter referred to as the "determination program") and a plurality of determination criteria used in the determination program. The measurement unit 50a, the arithmetic unit 50b, and the determination unit 50c of the processing unit 50 function based on the determination program when the determination device 1 is driven. Furthermore, the memory unit 51 stores, in association with each other, the ID information of multiple subjects, the measurement results received by the receiving unit 4 during the judgment test for each subject, the first, second, and third calculation results calculated by the processing unit 50 of the judgment device 1 based on the judgment program, and the judgment level results determined by the processing unit 50 based on these calculation results. Furthermore, the PC 5 is configured to have an input means 7 connected to the processing unit 50 for the operator to input information. The input means 7 is, for example, a keyboard. The display unit 6 is an example of an output unit of the determination device 1, and outputs (displays) the measurement data and calculation results of the processing unit 50, as well as the determination result. The display unit 6 is, for example, composed of a liquid crystal monitor. [Procedure for the Judgment Test] Based on the operation flow shown in Figure 3, the outline of the flange tightening skill judgment test (hereinafter referred to as the "judgment test") conducted by the judgment device 1 using the judgment program will be explained. The judgment test begins by starting the judgment device 1 and loading the judgment program stored in the memory unit 51 into the processing unit 50. Furthermore, the examiner or the person inputting data into the judgment device 1 (hereinafter referred to as the "operator") inputs the subject's ID information into the judgment device 1 via the input means 7. This ID information includes, for example, the subject's name and the date the judgment test was conducted. After the operator inputs the subject's ID information, they operate the input means 7 to input to the determination device 1 that the input is complete. As a result, the processing unit 50 of the determination device 1 determines that the ID information has been completed (S1). Subsequently, the measurement unit 50a executes a measurement step based on the judgment program and continuously measures the changes in the output signals of each strain gauge corresponding to each bolt 3 via the receiving unit 4. The processing unit 50 also stores the measurement data in the storage unit 51 (S2). Meanwhile, after inputting that the input is complete, the operator instructs the subject to start tightening each bolt 3 of the dummy flange 2 using a wrench S. Here, in the flange fastening operation, the subjects do not tighten a single bolt to the target tightening force Ftarget in a single tightening operation, but rather divide the tightening operation of a single bolt into m unit tightening operations and perform them in stages (where m > 1). Then, similar to the bolt tightening sequence of the so-called round method described in, for example, the American Society of Mechanical Engineers (ASME) or the Japan High Pressure Engineering Society (HPIS), they perform a circular operation in which unit tightening operations are performed sequentially for n bolts, repeating this operation m times to tighten the n bolts to the target tightening force Ftarget. In this way, since each bolt 3 is tightened by repeating multiple and the same number of unit tightening operations, the tightening force of each bolt 3 changes in stages along with each unit tightening operation. Therefore, the signal value of the output signal of each strain gauge for each bolt also changes in stages along with each unit tightening operation for each bolt 3. Once the subject has completed the tightening of all bolts 3, the operator inputs a message via the input means 7 indicating that the tightening of all bolts 3 (eight bolts 3a to 3h) has been completed. This causes the processing unit 50 to terminate the measurement step (S3). Furthermore, the judgment program can also be configured to have the measurement unit 50a measure time from the start of measurement in S2, and to automatically terminate the measurement when a certain period of time (for example, 600 seconds) has elapsed (S3). Next, the calculation unit 50b performs calculation steps to obtain the following three calculation results by calculating each of the measurement results stored in the storage unit 51 based on the determination program (S4). Specifically, the calculation unit 50b obtains the following skill judgment items: a first calculation result showing the variation in the output signal values ​​of each strain gauge during the tightening work of each bolt 3; a second calculation result showing the variation in the output signal values ​​of each strain gauge when the tightening work of each bolt 3 is completed; and a third calculation result showing the degree of each tightening force when the tightening work of each bolt 3 is completed. Hereafter, for convenience, the first calculation result will be denoted as "α", the second calculation result as "β", and the third calculation result as "γ". Here, α can evaluate whether each bolt 3 has been tightened in a way that suppresses the occurrence of flange rotation. β can evaluate whether all bolts 3 have been tightened on an average basis. γ can evaluate whether each bolt 3 has been tightened to the minimum tightening surface pressure required by the gasket placed between the pair of annular flanges of the dummy flange 2. Next, the determination unit 50c executes a determination step based on the determination program (S5). Specifically, the determination unit 50c uses α, β, and γ obtained in the calculation step as skill judgment items, compares each skill judgment item with pre-prepared judgment criteria, and determines, based on the comparison result, which of the three or more skill levels the subject's skill in bolt tightening work falls into. Each judgment criterion can be, for example, a range of multiple numerical values ​​in stages, as will be described in detail later. Next, the processing unit 50 executes the output step and outputs the judgment result from the judgment unit 50c to the display unit 6 (S6). With this, the judgment device 1 completes the judgment test. The operator and test subjects can find out the judgment result from the content displayed on the display unit 6. The details of the determination step (S5) and the output step (S6) will be explained below in order. [Judgment Step] The α obtained in the calculation step corresponds to the variation in the output signal values ​​of each strain gauge during the tightening operation of each bolt 3. Therefore, α represents the change in the tightening force of each bolt 3 over time. Accordingly, by using three skill judgment items, β and γ plus α, the judgment step makes it possible to capture the subject's skill in tightening each bolt 3 with multifaceted data, and the skills can be accurately evaluated by comparing them with each judgment criterion. The determination steps of the determination device 1 will be explained in detail below using the flowchart of the determination steps illustrated in Figure 4. In the flow shown in Figure 4, the judgment unit 50c, based on the judgment program, determines, for example, which of the three or more numerical ranges pre-prepared according to the levels of performance, each value of α, β, and γ belongs to. If any of the preceding skill judgment items among α, β, and γ is determined to be NG as a result of the comparison, the flow is terminated without judging the other subsequent skill judgment items. Here, as a specific example, in the calculation step (S4), the signal value of the output signal when each bolt 3 is tightened with the target tightening force Ftarget is set to 100%, and α[%], β[%], and γ[%] are obtained as the following calculation results. α [%]: The variation in the output signal values ​​of each strain gauge during the tightening operation of each bolt 3, which is the difference between the maximum and minimum output signal values ​​of each strain gauge for each bolt 3 at the completion of any unit tightening operation during the tightening operation of each bolt 3. Here, as an example, the maximum difference between the maximum and minimum output signal values ​​at the completion of all unit tightening operations during the tightening operation of each bolt 3 is used. β[%]: The difference between the maximum and minimum output signal values ​​of each strain gauge at the time each bolt 3 is tightened (flange fastening is completed), representing the variation in the output signal values ​​of each strain gauge at the time each bolt 3 is tightened (flange fastening is completed). γ[%]: The degree of tightening force for each bolt 3 at the completion of the tightening work (when the flange fastening work is completed) is the ratio of the tightening force for each bolt 3 at the completion of the tightening work (when the flange fastening work is completed) to the target tightening force Ftarget. The value of the target tightening force Ftarget for bolt 3 can be set as appropriate, but for example, it can be set to the value of the tightening force of bolt 3 corresponding to the recommended tightening surface pressure of the gasket sandwiched between the pair of annular flanges of the dummy flange 2. α[%], β[%], and γ[%] can also be obtained as calculation results other than those described above. In the following example, as an example, Ftarget was set to 60% to be the same as the recommended tightening surface pressure of the gasket. Furthermore, the judgment device 1 uses four judgment criteria for each skill judgment item. Specifically, to determine the level of α[%], as an example, four numerical ranges are used as judgment criteria: "A1" (within 13%), "A2" (over 13% and within 16%), "A3" (over 16% and within 20%), and "A4" (over 20%). Also, to determine the level of β[%], as an example, four numerical ranges are used as judgment criteria: "B1" (within 10%), "B2" (over 10% and within 15%), "B3" (over 15% and within 20%), and "B4" (over 20%). In addition, to determine the level of γ[%], as an example, four numerical ranges are used as judgment criteria: "C1" (51% or more and within 70%), "C2" (46% or more and within 75%), "C3" (36% or more and within 65%), and "C4" (less than 36% or greater than 75%). Furthermore, the numerical ranges of "C1" to "C3" for γ are, for example, partially superimposed on each other, and by determining γ in conjunction with α and β, the subject's level can be determined. Thus, in Embodiment 1, the level of α decreases in the order of A1, A2, A3, A4. Also, the level of β decreases in the order of B1, B2, B3, B4. In addition, the level of γ decreases in the order of C1, C2, C3, C4. In the assessment step, for example, if α[%] is judged as "A1", β[%] is judged as "B1", and γ[%] is judged as "C1", then the subject's skill level is determined to be equivalent to the highest rank, "III". Also in the assessment step, for example, if α[%] is judged as "A2 or higher", β[%] is judged as "B2 or higher", γ[%] is judged as "C2 or higher", and it does not correspond to "III", then the skill level is determined to be equivalent to "II". Also in the assessment step, for example, if α[%] is judged as "A3 or higher", β[%] is judged as "B3 or higher", γ[%] is judged as "C3 or higher", and it does not correspond to either "III" or "II", then the skill level is determined to be equivalent to "I". Furthermore, in the judgment step, for example, if α[%] is judged as "A4", if β[%] is judged as "B4", or if γ[%] is judged as "C4", the skill level will be judged as equivalent to "NG". The following flowchart will explain a specific example. The judgment unit 50c first determines whether α [%] is "A1" (S50) among the skill judgment items, and if it determines that it is "A1", it determines whether β [%] is "B1" (S51), and if it determines that it is "B1", it determines whether γ [%] is "C1" (S52), and if it determines that it is "C1", it determines that the subject's skill level corresponds to the highest rank "III judgment" (S53), and terminates the flow. On the other hand, as shown in Figure 4, if the determination unit 50c determines that α [%] is "A2" (S54), or if it determines that β [%] is not "B1" (S51), the determination unit 50c determines whether β [%] is "B2" or higher (S55). If it determines that β [%] is "B2" or higher, it determines whether γ [%] is "C2" or higher (S56). If it determines that γ [%] is "C2" or higher, it determines that the subject's skill level corresponds to "II," which is the next lowest level after "III" (S57), and terminates the flow. Thus, in the example flow shown in Figure 4, if α [%] is "A2," the setting is such that "III" cannot be obtained regardless of the determination results of β [%] and γ [%]. Alternatively, if the determination unit 50c determines that α [%] is "A3" (S61), or if it determines that β [%] is not "B2 or higher" (S55), the determination unit 50c determines whether β [%] is "B3 or higher" (S58). If it determines that β is "B3 or higher", it determines whether γ [%] is "C3 or higher" (S59). If it determines that γ is "C3 or higher", it determines that the subject's skill level corresponds to "I rating", which is the next lowest level after "II rating" (S60), and terminates the flow. Furthermore, if the determination unit 50c determines in S61 that α[%] is not "A3", it determines that α[%] is "A4" (S62). Also, if the determination unit 50c determines in S58 that β[%] is not "B3", it determines that β[%] is "B4" (S63). Alternatively, if the determination unit 50c determines in S59 that γ[%] is not "C3 or higher", it determines that γ[%] is "C4" (S64). After performing one of the determinations in S62 to S64, the determination unit 50c determines that the subject's skill level corresponds to an "NG" judgment (S65), and terminates the flow. In this way, the judgment device 1 determines, based on the results of the judgment unit 50c comparing the skill judgment items α, β, and γ with the respective judgment criteria, which of the three or more skill levels ("III judgment", "II judgment", "I judgment", "NG judgment") the subject's skill in tightening each bolt 3 corresponds to. Here, "III judgment" is a skill level where, for example, the subject can perform bolt tightening work on all lines of piping in a factory using spiral gaskets by themselves. "II judgment" is a skill level where, for example, the subject cannot perform bolt tightening work on flanges using spiral gaskets by themselves, but can perform bolt tightening work on flanges using joint sheet gaskets by themselves. "I judgment" is a skill level where, for example, the subject can perform bolt tightening work on flanges only when working in collaboration with a person with a skill level of "II judgment" or higher, but cannot perform bolt tightening work on flanges using spiral gaskets even when paired with a person with a skill level of "III judgment". "NG judgment" is a skill level where, for example, the subject cannot perform bolt tightening work, but can perform work such as maintenance on the flange surface, bolts and nuts. At the worksite, for example, by pre-attaching stickers indicating each skill level to a highly visible location on the helmet, the skill level of each worker can be easily checked. Thus, the judgment device 1 not only monitors or measures the tightening state of the bolts after fastening, but also makes it possible to evaluate the flange fastening work itself, which was previously difficult to evaluate. In particular, by performing a judgment step using α as a skill evaluation item, the judgment device 1 can evaluate the degree of variation in the tightening force of each bolt 3 at a given point in time during the fastening work. This makes it possible to determine whether or not flange rotation, which may occur due to the rapid tightening of a bolt, will occur. Furthermore, the judgment device 1 can determine whether or not uneven tightening or other problems may occur if the degree of variation in the tightening force of each bolt 3 at the time of completion of the tightening work (when the flange fastening work is completed) is above a certain level, by performing a judgment step using β as a skill judgment item. Furthermore, the judgment device 1 can determine whether or not problems such as pipe leaks that may occur due to insufficient bolt tightening force are caused by performing a judgment step using γ as a skill judgment item. As a result, the judgment device 1 and judgment program can objectively and clearly evaluate the flange fastening skills of a subject, regardless of their experience or intuition regarding bolt tightening work. Therefore, it is possible to appropriately select the most suitable personnel for flange fastening work. It should be noted that the numerical ranges for the α, β, and γ criteria mentioned above (A1-A4, B1-B4, C1-C4) are merely examples, and at least one of them can be changed as appropriate. [Output Step] As shown in Figure 5, the processing unit 50 displays the determination screen 10 on the display unit 6 in the output step. The determination screen 10 includes a first display unit 11, a second display unit 12, a third display unit 13, a fourth display unit 14, and a fifth display unit 15. The first display unit 11 shows the test date, the examinee's name, the examiner, and the result of the examination. The second display unit 12 graphically displays the measurement results of the tightening force of each of the eight bolts 3 (bolts 3a to 3h) at each point in time during the tightening process. The third display unit 13 displays the percentage [%] of the tightening force of each bolt relative to the target tightening force Ftarget, with the target tightening force Ftarget being 100%, with different background colors indicating each predetermined numerical range (for example, every 5%). The third display unit 13 also displays the degree of variation in the tightening force [%] (percentage relative to the target tightening force Ftarget) of each bolt 3 (bolts 3a to 3h). After the tightening of all bolts 3 is completed, the value of the degree of variation in the third display unit 13 is displayed as a value of β [%]. The fourth display section 14 shows the elapsed time of the judgment test. The fifth display section 15 shows a color chart to confirm which numerical range in the ratio [%] of the tightening force of each bolt 3 to the target tightening force Ftarget corresponds to each background color displayed in the third display section 13. The processing unit 50 displays the judgment screen 10 on the display unit 6 in the output step, and also displays the judgment result determined by the processing unit 50 in one of steps S53, S57, S60, or S65 in the flowchart of Figure 4 on the first display unit 11 of the judgment screen 10. The results of the subject's judgment test can be determined from the content displayed on this first display unit 11. As shown in Figure 6, when the operator selects the graph display button 16 on the judgment screen 10, the graph judgment screen 20 is displayed overlaid on the judgment screen 10. The sixth display unit 21, displayed in the center of the graph judgment screen 20, displays, for example, the elapsed time [sec] of the bolt tightening work in the judgment test on the horizontal axis, the gasket load [MPa] on the left vertical axis, and the ratio [%] of the tightening force of each bolt to Ftarget, where the target tightening force Ftarget for each bolt 3 is set to 100%, on the right vertical axis, creating a two-dimensional coordinate system graph. The right vertical axis of the sixth display unit 21 can also be set to the measured value of the tightening force [MPa] by operating the selection button 22. In the sixth display unit 21, the data for each bolt 3 is displayed in a curved manner over time, in a different manner, specifically in different colors. This makes it easy to check the values ​​of each skill judgment item (α, β, γ) in the calculation step S5 associated with tightening each bolt 3 in the sixth display unit 21. Specifically, the sixth display unit 21 can derive α [%] by comparing the variation in the tightening force of each bolt 3 at a given point in time during the tightening operation using the scale on the right vertical axis. This allows the operator and test subjects to determine, for example, which of the numerical ranges A1 to A4 the α [%] at a given point in the tightening operation falls into in the results of the judgment test. For example, if α [%] falls into A4 and its value exceeds 25%, the operator can determine that if a spiral gasket is used, the outer circumference of the hoop may be crushed, potentially reducing the sealing performance of the gasket due to a decrease in the sealing area. In this way, when the judgment screen 10 is displayed, the operator can confirm α [%] by looking at the variation [%] on the third display unit 13. Furthermore, the operator can view the subject's unit tightening actions in real time by displaying the judgment screen 20 during the tightening operation of the judgment test. For example, if the operator confirms that the change in tightening force ΔF exceeds 25% of the target tightening force Ftarget due to the unit tightening action performed on any bolt 3 during the first rotation of the flange fastening operation, the judgment test can be terminated immediately. The sixth display unit 21 displays the percentage of the tightening force at the completion of the tightening work for each bolt 3 as γ [%]. This allows the operator and test subjects to determine which of the numerical ranges C1 to C4 the result of the judgment test γ [%] falls into. By looking at the (Reference) [%] values ​​of the second display unit 12 and the sixth display unit 21 together, for example, if γ [%] does not reach the target tightening force Ftarget, it can be confirmed that there is a risk of leakage due to insufficient tightening force. On the graph judgment screen 20, by selecting one of the selection buttons 23 for each bolt 3a to 3h located in the upper right corner of the screen, only the curve for a specific bolt can be displayed. Furthermore, the sixth display unit 21 can be viewed in real time even during the measurement step (S2) of the judgment test by operating the judgment device 1. Thus, in the output step (S6), the display unit 6 displays α, β, and γ obtained by the calculation unit 50b in the calculation step in a manner that can be viewed by a person. Therefore, for example, by simply looking at the display contents of the display unit 6, operators and subjects can not only determine whether the subject's flange fastening skills are simply pass or fail according to the judgment criteria, but also objectively and clearly evaluate which of the three or more pre-prepared skill levels the subject's flange fastening skills correspond to. Furthermore, by storing each data of the subject's judgment test in the storage unit 51 in association with the subject's ID information, the subject's ID information and the results of the subject's past judgment tests can be checked together at any time. As a result, Embodiment 1 provides a flange fastening skill determination device and a flange fastening skill determination program that can objectively and clearly determine the skills of workers in fastening flanges. This makes it possible to easily form a team of workers who can be expected to produce a certain level of work quality by appropriately selecting personnel to perform flange fastening. This also makes it possible to reduce construction defects related to bolt tightening and improve the quality of construction work. Furthermore, by allowing subjects to objectively and clearly assess their own skill levels, it becomes possible to raise their overall technical level in a short period of time, and it is also possible to expect an improvement in the level of awareness necessary for engaging in flange fastening work. The following describes other embodiments of the present invention, focusing on the differences from Embodiment 1. <Embodiment 2> Figure 7 shows the graph judgment screen 20A displayed on the display unit 6 in the judgment device according to Embodiment 2. On the graph judgment screen 20A, a spatial coordinate system is used, and α, β, and γ are displayed in order, corresponding to the X, Y, and Z axes in the spatial coordinate system. This shows the numerical ranges for each skill level corresponding to "III judgment," "II judgment," and "I judgment" as cubic spaces Q1 to Q3, respectively. The numerical range for "NG judgment" is shown as a space that does not overlap with any of spaces Q1 to Q3. The α, β, and γ values ​​of the subject obtained in the judgment test are shown as the position of point P within the said spatial coordinate system. This display format allows the arithmetic unit 50b to display α, β, and γ obtained in the calculation step in a manner that can be confirmed by the operator and the subject. Furthermore, since α, β, and γ for each skill assessment item are displayed in correspondence with the X, Y, and Z axes in order, for example, the reason for the assessment result of the subject determined by the assessment unit 50c in the assessment step can be easily confirmed for each skill assessment item using the graph assessment screen 20A. In addition, to make it easier to distinguish between spaces Q1 to Q3, which represent "III assessment," "II assessment," and "I assessment," spaces Q1 to Q3 may be displayed in a manner that makes them distinguishable from each other (for example, by different colors). <Embodiment 3> Figure 8 shows the graph judgment screen 20B displayed on the display unit 6 in the judgment device according to Embodiment 3. The graph judgment screen 20B uses a two-dimensional coordinate system graph to display each skill judgment item individually and in parallel in the vertical direction. This allows the numerical ranges (A1-A4, B1-B4, C1-C4) of the "III judgment," "II judgment," "I judgment," and "NG judgment" criteria for each skill judgment item to be displayed together, and to show where the subject's α, β, and γ values ​​obtained in the judgment test (shown by thick lines L1-L3 in the figure) fall within the numerical range of each judgment criterion. This display format allows the calculation unit 50b to display α, β, and γ obtained in the calculation step in a manner that can be confirmed by the operator and the subject. Furthermore, each value of α, β, and γ can be individually and easily checked by comparing it with the range of each judgment criterion, and it is possible to examine in detail where the subject's α, β, and γ levels are relative to each criterion range. <Other Matters> In Embodiment 1, the determination unit 50c made determinations in the order of α, β, and γ, but the present invention is not limited thereto. The determination unit 50c may make determinations in any order of α, β, and γ. In Embodiment 1, the receiving unit 4 in the determination device 1 was separate from the PC 5, but the present invention is not limited to this configuration. For example, the receiving unit 4 may be placed inside the PC 5 and configured as a component of the PC 5. Similarly, the storage unit 51 is not limited to being placed inside the PC 5; for example, the storage unit may be placed on an external network connected to the PC 5. The configuration of the output unit in the judgment device is not limited to the display unit 6 which serves as the display for the so-called PC 5. For example, the judgment result in the judgment step of the judgment unit 50c may be output to paper, a sheet, or any of the various recording media. The bolt tightening operations for which the present invention can assess skill are not limited to bolt tightening operations for connecting pipe flanges in production plants, etc. For example, even bolt tightening operations for sealing, connecting, or assembling various structures such as pressure vessels such as decompression chambers or rotating equipment such as motor shafts can be successfully assessed. The strain gauges used in this invention may be provided individually for each of the multiple bolts used for fastening. Therefore, for example, strain gauges may be provided individually for each bolt at each position on a gasket placed between a pair of flanges of a dummy flange. In the embodiments described above, strain gauges were used as examples of clamping force detectors. However, the clamping force detector is not limited to strain gauges, and other configurations, such as piezoelectric elements, can also be used. In this case, by arranging piezoelectric elements between a pair of flanges at positions corresponding to each bolt, detection similar to that performed with strain gauges can be achieved. When using strain gauges as clamping force detectors, the strain gauges are not limited to temperature-compensated three-wire types; other types of strain gauges can also be used. In each of the embodiments described above, the skills related to flange fastening were assessed using all three skill assessment items, α, β, and γ. However, in some cases, it is also possible to assess the skills related to flange fastening using only two of these skill assessment items. Even in such cases, using two skill assessment items makes it possible to assess the skills related to flange fastening from multiple perspectives, which is useful. As described above, according to one aspect of the present invention, a flange fastening skill determination device and a flange fastening skill determination program can be provided that can objectively and clearly determine the skill level of an operator in fastening flanges, thus offering excellent advantages. Therefore, it is beneficial to widely apply this flange fastening skill determination device and flange fastening skill determination program to demonstrate the significance of these advantages. 1. Flange fastening skill determination device 2. Dummy flange 3. 3a-3h. Bolts with tightening force detectors 4. Receiving unit 5. Personal computer (PC) 6. Output unit 7. Input means 50. Processing unit 50a. Measurement unit 50b. Calculation unit 50c. Determination unit 51. Storage unit

Claims

1. A flange fastening skill determination device comprising: a receiving unit that receives output signals from each tightening force detector provided individually for each of the multiple bolts fastened to connect flanges, in accordance with the subject's tightening work on the multiple bolts; a measuring unit that obtains a plurality of measurement results received by the receiving unit, showing the progression of changes in each of the output signals from the start to the completion of the tightening work on each of the multiple bolts; a calculation unit that calculates the plurality of measurement results to obtain, as skill determination items, a first calculation result showing the variation in the output signal values ​​of each of the tightening force detectors during the tightening work on the multiple bolts, a second calculation result showing the variation in the output signal values ​​of each of the tightening force detectors at the completion of the tightening work on the multiple bolts, and a third calculation result showing the degree of each tightening force at the completion of the tightening work on the multiple bolts; a determination unit that determines, based on the result of comparing each of the skill determination items with a determination criterion, which of three or more skill levels the subject's skill in tightening each of the multiple bolts is at; and an output unit that outputs the determination result from the determination unit.

2. The flange fastening skill determination device according to claim 1, wherein the tightening operation of each of the plurality of bolts includes a plurality of unit tightening operations, and the calculation unit obtains the difference between the maximum and minimum values ​​of the output signal values ​​of each of the tightening force detectors at the completion of any of the unit tightening operations during the tightening operation of the plurality of bolts as the first calculation result.

3. The flange fastening skill determination device according to claim 2, wherein the calculation unit obtains as the first calculation result the maximum difference between the maximum and minimum values ​​of the output signal values ​​at the completion of all the unit tightening operations during the tightening work of the plurality of bolts.

4. The flange fastening skill determination device according to any one of claims 1 to 3, wherein the calculation unit obtains the difference between the maximum and minimum values ​​of the respective output signal values ​​at the completion of the tightening work of the plurality of bolts as the second calculation result.

5. The flange fastening skill determination device according to any one of claims 1 to 4, wherein the output unit is a display unit capable of displaying the determination result made by the determination unit, and the display unit displays the determination result made by the determination unit in a manner that distinguishes each skill level from one another.

6. The flange fastening skill determination device according to any one of claims 1 to 5, wherein the output unit is a display unit capable of displaying the third calculation result, and the display unit displays the third calculation result in different colors for each predetermined numerical range.

7. The flange fastening skill determination device according to any one of claims 1 to 6, further comprising a storage unit for storing the measurement results, the first, second, and third calculation results, and the determination results.

8. The flange fastening skill determination device according to claim 7, wherein the storage unit further stores the subject's ID information in association with the measurement result, the first, second, and third calculation results, and the determination result.

9. A flange fastening skill assessment program that causes a computer to execute the following steps: a calculation step that receives output signals from each tightening force detector, which is individually provided for each of the multiple bolts fastened to connect flanges, in accordance with the subject's tightening work on the multiple bolts, and obtains multiple measurement results that show the progression of changes in each of the received output signals from the start to the completion of the tightening work on each of the multiple bolts, and calculates the multiple measurement results to obtain a first calculation result that shows the variation in the output signal values ​​of each of the tightening force detectors during the tightening work on the multiple bolts, a second calculation result that shows the variation in the output signal values ​​of each of the tightening force detectors at the completion of the tightening work on the multiple bolts, and a third calculation result that shows the degree of each tightening force at the completion of the tightening work on the multiple bolts, each as a skill assessment item; a judgment step that determines which of three or more skill levels the subject's skill in tightening each of the multiple bolts is at based on the result of comparing each of the skill assessment items with a judgment criterion; and an output step that outputs the judgment result obtained in the judgment step.

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