Welding defect detection device, welding system, manufacturing device for welded pipe, method for detecting welding defect, method for manufacturing object to be welded, and program

Abstract

A welding defect detection device (1) comprises: a temperature sensor (10) that, each time a welding device (2) which welds a linear portion to be welded of an object to be welded by moving relative to the object moves, measures the temperature of a portion immediately after welding within the welded portion; and a controller (30) that determines that there is a blowhole in the portion immediately after welding when the temperature of the portion immediately after welding measured by the temperature sensor (10) is higher than a reference value by a certain value or more.

Description

Welding defect detection device, welding system, manufacturing device for welded pipe, method for detecting welding defect, method for manufacturing welded object, and program

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[0001] The present disclosure relates to a welding defect detection device, a welding system, a manufacturing device for a welded pipe, a method for detecting a welding defect, a method for manufacturing a welded object, and a program.

[0002] Some welding defect detection devices sense a welded object to detect welding defects.

[0003] For example, Patent Document 1 discloses a welding defect detection device including an ultrasonic flaw detector that uses ultrasonic waves to detect whether there is a flaw in a welded part, and a two-color thermometer that measures the temperature of the welded part, and determines the presence or absence of a welding defect from the measurement results of the ultrasonic flaw detector and the two-color thermometer.

[0004] Japanese Patent Laid-Open No. 58-205693

[0005] In the manufacturing device for a welded pipe described in Patent Document 1, not only the measurement result of the ultrasonic flaw detector but also the measurement result of the two-color thermometer is used to determine the presence or absence of a welding defect, so its configuration is complicated. Also, in Patent Document 1, it is not clear whether it is possible to detect voids, for example, blow holes, among welding defects.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a welding defect detection device, a welding system, a manufacturing device for a welded pipe, a method for detecting a welding defect, a method for manufacturing a welded object, and a program that can easily detect blow holes with a simple configuration.

[0007] To achieve the above object, the welding defect detection device according to the present disclosure includes a temperature sensor and a controller. The temperature sensor measures the temperature of the portion immediately after welding within the welded portion every time a welding device that welds a linear welded portion of the welded object by moving relative to the welded object moves. Further, when the temperature of the portion immediately after welding measured by the temperature sensor is higher than a reference value by a certain value or more, the controller determines that there is a blow hole in the portion immediately after welding.

[0008] According to the configuration of this disclosure, the controller determines that there is a blowhole in the welded portion if the temperature of the portion immediately after welding, as measured by the temperature sensor, is above a certain threshold value. In this way, the welding defect detection device can easily detect blowholes with a simple configuration.

[0009] Block diagram of the welding defect detection device according to Embodiment 1 of this disclosure Hardware configuration diagram of the controller included in the welding defect detection device according to Embodiment 1 of this disclosure Conceptual diagram of the temperature sensor and welding device included in the welding defect detection device according to Embodiment 1 of this disclosure Graph showing the relationship between welding speed and melting time obtained from a simulation assuming welding was performed with a welding device to which the welding defect detection device according to Embodiment 1 of this disclosure is attached Graph showing the temperature distribution of the welding material at the weld location obtained from a simulation assuming welding was performed with a welding device to which the welding defect detection device according to Embodiment 1 of this disclosure is attached Flowchart of the welding defect detection process performed by the welding defect detection device according to Embodiment 1 of this disclosure Side view of the front half of the welding pipe manufacturing device incorporating the welding defect detection device according to Embodiment 2 of this disclosure Side view of the rear half of the welding pipe manufacturing device incorporating the welding defect detection device according to Embodiment 2 of this disclosure Embodiment Plan view of a groove formed by a marking machine of a welding pipe manufacturing apparatus incorporating a welding defect detection device according to Embodiment 2 of this disclosure Plan view of another groove formed by a marking machine of a welding pipe manufacturing apparatus incorporating a welding defect detection device according to Embodiment 2 of this disclosure Plan view of yet another groove formed by a marking machine of a welding pipe manufacturing apparatus incorporating a welding defect detection device according to Embodiment 2 of this disclosure Block diagram of a welding device according to Embodiment 3 of this disclosure When a welding apparatus incorporating a welding defect detection device according to Embodiment 3 of this disclosure manufactures a welding pipe, the welding apparatus is shown in cross-sectional view Block diagram of a welding defect detection device according to Embodiment 4 of this disclosure Conceptual diagram of a displacement sensor provided by a welding defect detection device according to Embodiment 4 of this disclosure Block diagram of a welding pipe manufacturing apparatus according to Embodiment 5 of this disclosure Conceptual diagram of a displacement sensor provided by a welding pipe manufacturing apparatus according to Embodiment 5 of this disclosure Conceptual diagram of another displacement sensor provided by a welding pipe manufacturing apparatus according to Embodiment 5 of this disclosure

[0010] Hereinafter, a welding defect detection device, welding system, welding pipe manufacturing device, welding defect detection method, workpiece manufacturing method, and program according to embodiments of this disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

[0011] (Embodiment 1) The welding defect detection device according to Embodiment 1 is a device for detecting welding defects in a welding device used to weld two metal plates. This welding defect detection device detects voids, which are a type of welding defect, specifically blowholes as defined in Japanese Industrial Standard Z3001-4:2013. In other words, this welding defect detection device detects cavities where the welding material has not spread evenly. The configuration of this welding defect detection device will be described below with reference to Figures 1-3, using the case where the welding device is an arc weld as an example.

[0012] Figure 1 is a block diagram of the welding defect detection device 1 according to Embodiment 1. Figure 2 is a hardware configuration diagram of the controller 30 included in the welding defect detection device 1 according to Embodiment 1. Furthermore, Figure 3 is a conceptual diagram of the temperature sensor 10 and welding device 2 included in the welding defect detection device 1 according to Embodiment 1. Note that for ease of understanding, Figure 1 shows the configuration of the entire welding system 100, which includes the welding defect detection device 1 and the welding device 2, in addition to the welding defect detection device 1. Also, the metal plates 3 and 4, which are the objects to be welded, are also shown. Figure 2 omits the temperature sensor 10, marking device 40, etc., included in the welding defect detection device 1.

[0013] As shown in Figure 1, the welding defect detection device 1 is attached to the welding device 2 that welds the metal plates 3 and 4. The welding device 2 is, for example, an arc welding device. The welding device 2 is positioned on the stage of the conveying device 5.

[0014] In the conveying device 5, the metal plates 3 and 4 are placed on the stage with their ends facing each other in order to join them. The conveying device 5 moves the stage in one direction, specifically in the direction of arrow A. The direction of arrow A is the direction in which the joined ends of the metal plates 3 and 4, i.e., the joining surface, extend. Also, the direction of arrow A is the direction in which the joining surface of the metal plates 3 and 4, i.e., the portion that will become the weld, extends in a straight line. By moving the stage in the direction of arrow A, the conveying device 5 moves the metal plates 3 and 4 relative to the welding device 2.

[0015] The welding device 2 is positioned on the transport device 5 and on the joining surfaces of the metal plates 3 and 4. When the stage of the transport device 5 starts moving, the welding device 2 starts welding the end faces of the metal plates 3 and 4 together. The welding device 2 continues this welding until the stage of the transport device 5 stops moving. In this way, the welding device 2 moves relative to the metal plates 3 and 4 and sequentially welds the end faces of the metal plates 3 and 4 together. That is, the welding device 2 welds each part within the welding area in the direction opposite to the direction of arrow A. As a result, the welding device 2 forms a continuous weld in the direction opposite to the direction of arrow A, i.e., a linear weld.

[0016] In this type of welding, voids, specifically blowholes, which are a type of welding defect, can occur in the welded area. Here, a blowhole is defined in Japanese Industrial Standard Z3001-4:2013 as a spherical cavity that occurs in the weld metal. These blowholes are more likely to occur when the movement speed of the stage of the conveying device 5 is high. The inventor's findings are shown in Figure 4.

[0017] Figure 4 is a graph showing the relationship between welding speed and melting time obtained from a simulation assuming welding was performed using a welding apparatus 2 to which the welding defect detection device 1 is attached.

[0018] The graph shown in Figure 4 is obtained by simulating the melting time of the welding material at the weld point using analysis software, assuming that the center of a copper plate with a width of 5 mm and a thickness of 0.4 mm is welded in an atmospheric environment of 20°C. In the simulation using the analysis software, the copper plate to be welded was assumed to have the following physical properties: density of 8.96 g / cm³, specific heat of 0.385 J / (kg·K), and thermal conductivity of 398 W / (m·K). Furthermore, it was assumed that heat with a Gaussian distribution centered on the center of the copper plate was applied to the copper plate at an initial temperature of 20°C. In addition, when the width of the portion of the welding material that exceeds the melting point at the weld point is defined as the weld width, the output of the welding device 2 was adjusted so that the weld width remained constant regardless of the welding speed. Specifically, the output of the welding device 2 was adjusted so that the weld width was 0.3 mm. The output power at that time was 640, 930, 1180, 1390, and 1570 W, respectively, when the welding speed was 167, 333, 500, 667, and 833 mm / sec.

[0019] Referring to Figure 4, it can be seen that the faster the welding speed, the shorter the melting time for the welding material above its melting point. From this, it can be seen that when a blowhole occurs inside the molten material, the faster the welding speed, the more difficult it becomes to ensure enough time for the blowhole to rise to the surface of the molten welding material. As a result, blowholes are more likely to remain. For this reason, measures to suppress the occurrence of blowholes by slowing down the welding speed can be considered. However, in that case, the welding efficiency of welding apparatus 2 decreases. Therefore, in order to detect blowholes when they occur while ensuring a certain level of welding efficiency, the inventor investigated the conditions under which blowholes occur. The results are shown in Figure 5.

[0020] Figure 5 is a graph showing the temperature distribution of the welding material at the welded area, obtained from a simulation assuming welding was performed using a welding apparatus 2 to which the welding defect detection device 1 is attached. Figure 5 illustrates various parts of the workpiece and shows the maximum temperature of the welding material at each part.

[0021] The graph shown in Figure 5 is obtained by simulating the maximum temperature of the welding material at the weld point using analysis software, assuming that two flat copper plates, each 2.5 mm wide and 0.4 mm thick, are welded together in an atmospheric environment of 20°C. In this simulation, the physical properties of the copper plates to be welded were assumed to be the same as in Figure 4. The initial temperature and the method of applying heat with a Gaussian distribution were also assumed to be the same as in Figure 4. Furthermore, the welding speed was set to 167 mm / second, and the output of welding device 2 was set to 640 W. In this simulation, it was assumed that there was a square-shaped blowhole with a width and depth of 0.2 mm at a depth of 0.05 mm from the heat transfer surface of the copper plate, and the thermal conductivity of the area with the blowhole was set to an extremely low 398 × 10⁻⁹ W / m·K compared to other areas.

[0022] Referring to Figure 5, it can be seen that there are areas where the maximum temperature of the weld material is higher than in other areas. More specifically, while there are many areas where the maximum temperature of the weld material remains around 1200°C, there is an area where the maximum temperature of the weld material is 1576.7°C, which is hotter than in other areas. This hotter area is the area where the aforementioned square-shaped blowhole was assumed to be located. From this, it can be seen that the maximum temperature is higher in areas with blowholes than in areas without blowholes. Therefore, if the maximum temperature of the weld material is measured and found to be higher than the maximum temperature of the normal areas, it can be inferred that a blowhole has occurred.

[0023] Returning to Figure 1, the welding defect detection device 1 utilizes this phenomenon to detect whether or not blowholes occur at the welded area. To detect whether or not blowholes occur at the welded area, the welding defect detection device 1 includes a temperature sensor 10, a storage device 20 that stores the measurement results of the temperature sensor 10, a controller 30 that detects whether or not blowholes occur from the measurement results of the temperature sensor 10, and a marking device 40 that marks the metal plates 3 and 4 of the workpiece if the controller 30 determines that blowholes exist.

[0024] The temperature sensor 10 is a sensor that measures the temperature of the welded area, and to measure the temperature accurately, it is configured, for example, as a two-color thermometer. The temperature sensor 10 is positioned on the stage of the transport device 5 described above. In detail, the temperature sensor 10 is positioned on the stage, on the joint surface of the metal plates 3 and 4, similar to the welding device 2. This allows the temperature sensor 10 to measure the temperature of the welded area of ​​the metal plates 3 and 4 when the joint surface of the metal plates 3 and 4 is welded. Furthermore, as shown in Figure 3, the temperature sensor 10 is positioned downstream of the welding device 2, that is, on the side indicated by arrow A of the welding device 2. This allows the temperature sensor 10 to measure the temperature of the welded area immediately after the welding device 2 has welded the joint surface of the metal plates 3 and 4.

[0025] "Immediately after" refers to the time immediately after welding when the welding material is still molten. For example, as can be seen in Figure 4, "immediately after" depends on the welding speed, i.e., the movement speed of the conveying device 5, but it is only 0.5 to 2 milliseconds after welding.

[0026] The temperature sensor 10 receives a measurement command from the controller 30 shown in Figure 1 and measures the temperature based on that command. The controller 30 transmits the measurement command when the welding device 2 is welding. The temperature sensor 10 receives the measurement command and measures the temperature, thereby measuring the temperature of the welded area immediately after welding by the welding device 2. The temperature sensor 10 sends the measured temperature data to the controller 30, and the controller 30 stores the measured temperature data in the storage device 20.

[0027] The storage device 20 stores past measurement data from the temperature sensor 10. More specifically, the storage device 20 stores temperature data transmitted via the controller 30 upon instruction from the controller 30. The storage device 20 also transmits the stored past temperature data to the controller 30 upon request from the controller 30.

[0028] As shown in Figure 2, the controller 30 includes a computer consisting of a processor 31 and a memory 32, and a network interface 33. These processor 31, memory 32, and network interface 33 are connected by a bus 34. Furthermore, the network interface 33 connects the processor 31 to each component of the welding defect detection device 1, specifically the temperature sensor 10, storage device 20, and marking device 40 shown in Figure 1. The network interface 33 also connects the processor 31 to the welding device 2. This allows the network interface 33 to receive output signals from the welding device 2 and further control the temperature sensor 10, storage device 20, and marking device 40.

[0029] The network interface 33 connects the processor 31, the temperature sensor 10, the storage device 20, and the marking device 40 or welding device 2 via a network, such as the Internet. Therefore, the processor 31, temperature sensor 10, storage device 20, and marking device 40 do not need to be housed together in a single enclosure; although not shown, they may be located in separate places, for example, each housed in a separate enclosure.

[0030] Memory 32 stores various programs for controlling each part of the welding defect detection device 1, such as a welding defect detection program. The processor 31 then executes its operation program to perform welding defect detection processing that controls the temperature sensor 10, the storage device 20, and the marking device 40. As a result, the controller 30 performs welding defect detection processing of the welding defect detection device 1.

[0031] The detailed flow will be described later, but the controller 30 commands the temperature sensor 10 to measure the temperature during welding and acquires the temperature data measured by the temperature sensor 10. The controller 30 then stores the current temperature data acquired from the temperature sensor 10 in the storage device 20 and reads past temperature data from the storage device 20. The controller 30 determines that there is a blowhole in the welded area of ​​the metal plates 3 and 4, which are the workpieces to be welded, if the current temperature data is higher than a reference value determined from past temperature data, for example, the previous temperature data, by a certain value or more. If the controller 30 determines that there is a blowhole, it commands the marking device 40 to mark the area.

[0032] The marking device 40 places a mark near the location of a blowhole to indicate the presence of a blowhole. In detail, although the exact location of the marking device 40 is not shown in Figure 1, it is positioned on the stage of the transport device 5 and downstream of the welding device 2, i.e., on the side indicated by arrow A. The marking device 40 then places a mark on the welding location below it, in accordance with a command from the controller 30. As a result, the marking device 40 places a mark near the location of a blowhole to indicate the presence of a blowhole. Consequently, the marking device 40 notifies the user of the welding defect detection device 1 that a blowhole is present.

[0033] Thus, the welding defect detection device 1, with its simple configuration consisting of a temperature sensor 10, a storage device 20, a controller 30, and a marking device 40, easily detects whether or not there are blowholes in the metal plates 3 and 4 that are to be welded. When blowholes are found in the metal plates 3 and 4, the welding defect detection device 1 notifies the user of the presence of blowholes by marking them.

[0034] Next, with reference to Figure 6, the detailed operation of the welding defect detection device 1 will be described. In the following description, it will be assumed that the welding defect detection device 1 is activated when a start switch (not shown) for the welding defect detection device 1 is pressed.

[0035] Figure 6 is a flowchart of the welding defect detection process performed by the welding defect detection device 1.

[0036] When the welding defect detection device 1 is activated by pressing a start switch (not shown), the processor 31 of the welding defect detection device 1 executes the welding defect detection program, and the welding defect detection process flow shown in Figure 6 is started.

[0037] First, as shown in Figure 6, the controller 30 determines whether or not welding is being performed (step S1). Specifically, the welding device 2 outputs a welding execution signal when it performs welding. The controller 30 checks whether or not this welding execution signal is being output, and if it is not being output, it determines that welding is not being performed (No. in step S1). If the controller 30 determines that welding is not being performed, it returns to step S1 again. Thus, the controller 30 continues step S1 until the welding device 2 starts welding.

[0038] On the other hand, if the controller 30 outputs a welding execution signal, it determines that welding is being performed (Yes in step S1). In that case, the controller 30 issues a measurement command to the temperature sensor 10 (step S2). When the temperature sensor 10 receives the measurement command signal from the controller 30, it measures the temperature of the welded area of ​​the metal plates 3 and 4, which are the workpieces to be welded, on the stage of the transport device 5 shown in Figure 1. For example, the temperature sensor 10 measures the temperature of the welded area multiple times and takes the temperature data of the highest temperature at that time as the measured value. The temperature sensor 10 transmits this measured value data, i.e., the temperature data, to the controller 30.

[0039] Next, as shown in Figure 6, the controller 30 acquires temperature data from the temperature sensor 10 (step S3). Although not shown, the controller 30 is electrically connected to the control unit of the transport device 5. The controller 30 acquires temperature data from the temperature sensor 10 and also acquires stage position data of the transport device 5 from the control unit of the transport device 5.

[0040] Next, the controller 30 reads the previous temperature data from the storage device 20 and determines a reference value. It also stores the current temperature data acquired in step S3 in the storage device 20 (step S4). In more detail, the storage device 20 stores the temperature data along with the stage position data of the transport device 5 each time the temperature sensor 10 measures the temperature and the controller 30 acquires that temperature data. The controller 30 reads the past temperature data up to the previous time from the storage device 20. The controller 30 then determines a reference value that will serve as the basis for temperature changes at the welding points of the metal plates 3 and 4, which are the objects to be welded, from the previously read temperature data. For example, the controller 30 uses the previous temperature data as the reference value. Furthermore, the controller 30 stores the current temperature data acquired in step S3 in the storage device 20 along with the stage position data of the transport device 5 described in step S3.

[0041] In this flowchart, the reference value is the previous temperature data, but the reference value may be the average of past temperature data up to the previous measurement. Alternatively, it may be a representative value, mean, median, etc., of temperature data obtained in advance through experiments.

[0042] Next, the controller 30 determines whether the temperature data acquired in step S3 is greater than a certain value or more than the reference value (step S5). If the determination is simply whether the current temperature data is greater than or less than the reference value, it would include cases where it is only slightly greater than the reference value. Therefore, in this step, it is determined whether the current temperature data is greater than a certain value or more than the reference value.

[0043] When the controller 30 determines that the current temperature data is greater than or equal to a certain value above the reference value (Yes in step S5), it determines that there is a blowhole at the welding location. And in that case, the controller 30 performs marking (step S6). Specifically, the controller 30 instructs the marking device 40 to perform marking, causing the marking device 40 to mark a mark indicating that there is a blowhole near the welding location of the metal plates 3 and 4, which are the workpieces to be welded. At this time, the controller 30 may transmit the position data of the stage of the transfer device 5, which was described in step S3, to the marking device 40, and cause the marking device 40 to mark near the welding location measured by the temperature sensor 10.

[0044] On the other hand, when the controller 30 determines that the current temperature data is not greater than or equal to a certain value above the reference value (No in step S5), it proceeds to step S7.

[0045] In step S7, the controller 30 determines whether welding has ended (step S7). As described above, the welding device 2 outputs a welding execution signal when performing welding. The controller 30 checks whether the welding execution signal is output, and if it is output, determines that welding has not ended (No in step S7). Then, it returns to step S1. Thereby, the controller 30 continues the welding defect detection process of steps S1 - S7.

[0046] When the welding is not completed, if the conveying device 5 continues to operate, due to the conveying, welding is performed on a new location of the metal plates 3 and 4, which are the workpieces to be welded. The new location is a location on the opposite side of the arrow A shown in FIG. 1 that is continuous from the location measured by the temperature sensor 10 this time. By returning to step S1 and continuing the welding defect detection process, the controller 30 determines whether there is a blowhole at the new location. By repeating the welding defect detection process of steps S1 - S7, each time the welding device 2 welds each continuous part of the welding location extending in the direction opposite to the arrow A of the metal plates 3 and 4 in the same direction, the temperature sensor 10 measures each of these parts. Further, the controller 30 detects whether there is a blowhole for each welded part formed on each of these parts.

[0047] On the other hand, when the controller 30 determines that the welding has ended (Yes in step S7), since there is no need to continue the welding defect detection process, the welding defect detection process is terminated.

[0048] As described above, in the welding defect detection process of the welding defect detection device 1, the controller 30 determines whether there is a blowhole at the welding location based on whether the current temperature data is greater than or equal to a certain value above the reference value. As a result, the welding defect detection device 1 has a simple structure and detects whether there is a blowhole in the metal plates 3 and 4, which are the workpieces to be welded.

[0049] As described above, in the welding defect detection device 1 according to the first embodiment, when the temperature of the welding target portion of the metal plates 3 and 4, which are the workpieces to be welded, measured by the temperature sensor 10 is higher than the reference value by a certain value or more, the controller 30 determines that there is a blowhole in the welding of the welding target portion. Thus, the welding defect detection device 1 has a simple structure. In addition, the welding defect detection device 1 can easily detect blowholes.

[0050] Note that the welding locations of the metal plates 3 and 4 described above are an example of the welding locations referred to in the present disclosure.

[0051] (Embodiment 2) In Embodiment 1, the objects to be welded are flat metal plates 3 and 4. However, in the welding defect detection device 1, the objects to be welded only need to have linear welded areas. Here, linear means that the welded areas are long and continuous, such as in a straight line or curved shape, when viewed from above. Therefore, the shape of the objects to be welded is arbitrary as long as this condition is met. For example, the objects to be welded may be welded pipes.

[0052] In Embodiment 2, the workpiece to be welded is a welded pipe, and the welding defect detection device 1 is incorporated into the welding apparatus in the manufacturing apparatus for that welded pipe. The welding defect detection device 1 according to Embodiment 2 will be described below with reference to Figures 7 and 8. Embodiment 2 will be described in a configuration that differs from that of Embodiment 1.

[0053] Figure 7 is a side view of the front half of a welded pipe manufacturing apparatus 6 incorporating the welding defect detection device 1 according to Embodiment 2. Figure 8 is a side view of the rear half of the same manufacturing apparatus 6. In the Cartesian coordinate system XYZ shown in the figures, when the upstream and downstream directions of the welded pipe manufacturing apparatus 6 are oriented horizontally, the vertical direction is the Z-axis, the upstream and downstream directions in the horizontal direction are the X-axis, and the direction perpendicular to the Z-axis and X-axis is the Y-axis. Embodiment 2 will refer to this Cartesian coordinate system XYZ as appropriate.

[0054] As shown in Figures 7 and 8, the welded pipe manufacturing apparatus 6 includes an uncoiler 60, a strip joining machine 61, an accumulator 62, marking machines 63 and 64, a forming machine 65, a welding machine 7, a drawing machine 66, a cutting machine 67, and a recoiler 68.

[0055] The welding pipe manufacturing apparatus 6 is supplied with a strip of metal sheet wound into a coil. The manufacturing apparatus 6 then manufactures welding pipes from this strip of metal sheet. The uncoiler 60 shown in Figure 7 unwinds the coiled strip of metal sheet and pulls out one end of the strip of metal sheet from the coil.

[0056] In detail, the uncoiler 60 has a cylindrical holder 601 that holds a coil of strip metal plates from the inside, and a drive unit (not shown) that rotates the holder 601. The drive unit (not shown) rotates the holder 601 in the opposite direction to the winding direction of the coil. As a result, the uncoiler 60 pulls out one end of the strip metal plate from the coil. The uncoiler 60 supplies the pulled-out end of the strip metal plate to the strip joining 61.

[0057] The strip joining 61 connects one end of a strip of metal to one end of another strip of metal. More specifically, in the uncoiler 60 (not shown), once a strip of metal is completely pulled out of a coil, the next coil is set, and one end of the strip of metal is pulled out from the next coil. The strip joining 61 connects the other end of the strip of metal from the previous coil (opposite to the first end) to the pulled-out end of the strip of metal from the next coil.

[0058] To describe its configuration, the strip joining 61 has a welding device (not shown). The strip joining 61 connects the other end of the strip metal plate of the previous coil to one end of the strip metal plate of the next coil using its welding device.

[0059] Meanwhile, the accumulator 62 stores a certain length of the strip metal sheet drawn from the coil. More specifically, the accumulator 62 is equipped with a roller (not shown). The middle portion of the strip metal sheet drawn from the coil is placed on this roller. The roller then winds up the middle portion of the strip metal sheet for a certain length to be supplied during the welding time of the strip joining 61, in order to prevent the supply of the strip metal sheet from stopping while welding is in progress at the strip joining 61. In this way, the accumulator 62 retains a certain length of the strip metal sheet. After winding up the middle portion of the strip metal sheet for a certain length, the accumulator 62 feeds out one end of the strip metal sheet, that is, the +X end portion in the Cartesian coordinate system XYZ shown in Figure 7, in the +X direction. In this way, the +X end portion of the strip metal sheet is fed to the stamping machine 63.

[0060] The marking machines 63 and 64 are devices that form grooves in a strip of metal plate in order to form grooves on the inner wall of the welded pipe to be manufactured, and more specifically, in order to form grooves on the inner wall that will improve the heat exchange performance when the welded pipe is used as a heat transfer pipe.

[0061] More specifically, the stamping machines 63 and 64, although not shown in the figures, have a first roll with grooves formed on its outer circumference, called a groove roll or abbreviated as a G roll, and a second roll with no irregularities on its outer circumference and a smooth curved surface. The stamping machine 63 sandwiches a strip of metal, which has been fed from the accumulator 62 and whose tension has been adjusted by the dancer rolls 631 and 632 shown in Figure 7, between the first and second rolls. The stamping machine 63 passes the strip of metal between the first and second rolls while the first and second rolls are pressed against the strip of metal. In this way, the stamping machine 63 forms grooves in the strip of metal.

[0062] Furthermore, the engraving machine 64 has a first roll and a second roll separate from the first and second rolls of the engraving machine 63, for forming grooves different from those formed by the engraving machine 63. The engraving machine 64 sandwiches the strip-shaped metal plate, which has grooves formed by the engraving machine 63 and whose tension has been adjusted by the dancer rolls 632 and 633, between the separate first roll and the separate second roll. The engraving machine 64 also presses these first and second rolls against the strip-shaped metal plate. Furthermore, the engraving machine 64 passes the strip-shaped metal plate between the first and second rolls. As a result, the engraving machine 64 forms grooves in the strip-shaped metal plate that are different from those formed by the engraving machine 63.

[0063] The stamping machines 63 and 64 perform the above-described processing on the strip-shaped metal sheet to form, for example, a herringbone-like groove on the strip-shaped metal sheet, where multiple grooves extending in a V-shape in plan view are arranged in the direction of the strip's extension. Alternatively, the stamping machines 63 and 64 form multiple intersecting grooves in an X-shape in plan view on the strip-shaped metal sheet. Or, the stamping machines 63 and 64 form an emboss on the strip-shaped metal sheet. By doing so, the stamping machines 63 and 64 improve the heat exchange efficiency of the welded pipes when the manufactured welded pipes are used as heat transfer tubes in a heat exchanger. After forming such grooves on the strip-shaped metal sheet, the stamping machines 63 and 64 send the portion with the grooves to the forming device 65 shown in Figure 8.

[0064] The forming device 65 first curves the strip-shaped metal sheet sent from the stamping machines 63 and 64 in the width direction of the strip, and then curves the strip-shaped metal sheet further to form a tubular shape by joining the two ends of the strip-shaped metal sheet in the width direction, i.e., the +Y end and the -Y end. For example, the forming device 65 forms the strip-shaped metal sheet into the shape of a circular tube. In this way, the forming device 65 forms a tubular body with the Y ends joined together on the portion of the strip-shaped metal sheet sent from the stamping machines 63 and 64. The forming device 65 then sends the tubular body to the welding device 7.

[0065] The welding apparatus 7 welds the joints of the tubular bodies described above. The welding apparatus 7 is, for example, a high-frequency induction heating type or a TIG (Tungsten Insert Gas) type welding apparatus. The welding apparatus 7 creates a welded tube portion on the +X end side of the strip metal plate by welding the joints of the tubular bodies formed on the +X end side of the strip metal plate. The welding apparatus 7 then sends the welded tube portion of the strip metal plate to the draw machine 66.

[0066] The drawing machine 66 adjusts the outer and inner diameters of the welded pipe portion produced by the welding device 7. The drawing machine 66, although not shown in the figure, is equipped with a die that is smaller than the outer diameter of the welded pipe produced by the welding device 7 and has a through hole of the same diameter as the target outer diameter. The drawing machine 66 then passes the welded pipe portion of the strip metal plate through the die and draws it out. In this way, the drawing machine 66 processes the welded pipe portion of the strip metal plate to an outer diameter the same as the diameter of the through hole in the die. The drawing machine 66 then sends the processed welded pipe portion of the strip metal plate to the cutting machine 67 shown in Figure 8.

[0067] The cutting machine 67 is equipped with a cutter 671 that can move in the direction from the front to the back in Figure 8, that is, in the Y direction. By moving the cutter 671, the cutting machine 67 cuts the welded pipe portion of the strip metal plate, which has been processed by the drawing machine 66, to the desired length. In this way, the cutting machine 67 produces a welded pipe of the desired length. The cutting machine 67 then feeds the welded pipe of the desired length to the recoiler 68.

[0068] The recoiler 68 has a cylindrical winding section 681, and winds the welded pipe, which has been cut to the desired length by the cutting machine 67, onto the winding section 681 to form a coil again. In this way, the recoiler 68 makes the manufactured welded pipe ready to be supplied to an external device.

[0069] The coiled strip of metal sheet attached to the uncoiler 60 is, for example, a rolled copper or copper alloy sheet. The width of the strip of metal sheet should be corresponding to the outer diameter of the welded pipe before it is reduced in diameter by the drawing machine 66.

[0070] In this way, the welded pipe manufacturing apparatus 6 uses an uncoiler 60 to pull out a strip of metal sheet wound into a coil, and stamping machines 63 and 64 to form grooves in the strip of metal sheet. Furthermore, a forming apparatus 65 bends the strip of metal sheet in the Y direction to form a tubular body with the +Y end and -Y end joined together. Then, a welding apparatus 7 welds the joint formed by joining the +Y end and -Y end of the tubular body to manufacture a welded pipe.

[0071] In Embodiment 2, as shown in Figure 8, a welding defect detection device 1 is provided adjacent to the welding device 7 of the welded pipe manufacturing apparatus 6. The configuration of the welding defect detection device 1 is the same as in Embodiment 1. Therefore, in Embodiment 2, the description of the configuration of the welding defect detection device 1 is omitted. In Embodiment 2, by incorporating the welding defect detection device 1 into the welded pipe manufacturing apparatus 6, the welding defect detection device 1 detects blowholes when they occur in each welded portion of the welded pipe. When a blowhole is found, the welding defect detection device 1 marks the corresponding portion of the welded pipe with a mark indicating the presence of a blowhole, thereby informing the user of the welding defect. As a result, the portion of the welded pipe with the blowhole can be cut and removed. This enables the welded pipe manufacturing apparatus 6 to supply high-quality welded pipes.

[0072] As described above, the welding defect detection device 1 according to Embodiment 2 is incorporated into the welding pipe manufacturing apparatus 6. Therefore, the welding pipe manufacturing apparatus 6 can easily detect blowholes. Furthermore, the welding pipe manufacturing apparatus 6 can notify the user of the location of blowholes by marking the location where blowholes are detected.

[0073] It has been explained that the forming apparatus 65 forms a tubular shape by joining the +Y end and the -Y end of the strip metal sheet. This tubular-shaped strip metal sheet before welding is an example of a tubular section as referred to in this disclosure. The +Y end and the -Y end of the strip metal sheet are an example of a first end face and a second end face in the width direction of the strip metal sheet as referred to in this disclosure. It has also been explained that the accumulator 62 feeds the +X end portion of the strip metal sheet in the +X direction. The +X direction in which the strip metal sheet is fed is an example of a feeding direction of the strip metal sheet as referred to in this disclosure. Furthermore, the +X end portion of the strip metal sheet is an example of a portion of the strip metal sheet on the feeding direction side as referred to in this disclosure. In addition, the joint of the tubular body formed on the +X end side of the strip metal sheet is an example of a joint between the opposing first end face and second end face of the strip metal sheet as referred to in this disclosure.

[0074] (Modification) In Embodiment 2, the stamping machines 63 and 64 form herringbone-shaped grooves on the strip-shaped metal plate, where multiple V-shaped grooves are arranged in the direction of the strip's extension when viewed from above, or grooves that intersect in an X-shape when viewed from above. However, the stamping machines 63 and 64 are not limited to these. The stamping machines 63 and 64 may also form grooves other than herringbone-shaped grooves and grooves that intersect in an X-shape.

[0075] Figure 9A is a plan view of grooves formed by marking machines 63 and 64 of a welding pipe manufacturing apparatus 6 incorporating the welding defect detection device 1 according to Embodiment 2. Figure 9B is a plan view of another groove formed by the same marking machines 63 and 64. Figure 9C is a plan view of yet another groove formed by the same marking machines 63 and 64.

[0076] As shown in Figure 9A, the stamping machines 63 and 64 may form multiple V-shaped grooves in plan view at different angles on the strip metal plate 91. Alternatively, as shown in Figure 9B, the stamping machines 63 and 64 may form a diamond-shaped groove in plan view on the strip metal plate 91 by having multiple linear grooves intersect. Furthermore, as shown in Figure 9C, the stamping machines 63 and 64 may form the strip metal plate 91 into a shape in which multiple grooves inclined with respect to the longitudinal direction and multiple circular grooves arranged in a matrix are mixed together in plan view.

[0077] (Embodiment 3) In Embodiment 1, the welding apparatus 2 is an arc welding apparatus. In Embodiment 2, the welding apparatus 7 is a high-frequency induction heating or TIG welding apparatus. However, the welding apparatuses 2 and 7 into which the welding defect detection device 1 is incorporated are not limited to these. The welding apparatuses 2 and 7 only need to weld linear welding points on the workpiece by moving relative to the workpiece. Therefore, the welding method of the welding apparatuses 2 and 7 is arbitrary.

[0078] The welding defect detection device 1 according to Embodiment 3 is attached to an electron beam welding apparatus and detects whether or not blowholes occur in the welding apparatus. The welding defect detection device 1 according to Embodiment 3 will be described below with reference to Figures 10 and 11. Embodiment 3 will be described in a configuration different from Embodiments 1 and 2.

[0079] Figure 10 is a block diagram of the welding defect detection device 1 according to Embodiment 3. Figure 11 is a cross-sectional view of the welding apparatus 8 when the welding apparatus 8, into which the welding defect detection device 1 is incorporated, is used to manufacture welded pipes. Note that Figure 10 shows the welding apparatus 8 in addition to the welding defect detection device 1 for ease of understanding.

[0080] As shown in Figure 10, the welding defect detection device 1 is attached to the welding apparatus 8 which has a vacuum chamber 81.

[0081] The welding apparatus 8 is an electron beam welding apparatus. In electron beam welding, electrons emitted from a cathode in a vacuum are accelerated with high voltage and collide with the workpiece, and the resulting energy is used for welding. For this reason, the welding apparatus 8 has the vacuum chamber 81 described above. The metal plates 3 and 4, which are the workpieces to be welded, are passed through the vacuum chamber 81. The welding apparatus 8 welds these metal plates 3 and 4 inside the vacuum chamber 81.

[0082] The welding defect detection device 1 according to Embodiment 3 is attached to such a welding apparatus 8 and detects blowholes when they occur at the weld. The welding defect detection device 1 can detect blowholes at the weld inside the vacuum chamber 81 simply by having the temperature sensor 10 measure the temperature of the weld inside the vacuum chamber 81. For this reason, the welding defect detection device 1 does not require a complex configuration of the welding system itself, including the welding apparatus 8, and the welding system can be made simpler.

[0083] The welding apparatus 8 may also be used to manufacture welded pipes. In that case, as shown in Figure 11, a strip of metal sheet 91 is passed through the vacuum chamber 81. The vacuum chamber 81 is provided with forming rollers 82-85 that form the strip of metal sheet 91 into a tubular shape. The forming rollers 82-85 curve the strip of metal sheet 91 in the width direction of the strip, and then curve the strip of metal sheet 91 further, thereby forming a tubular shape by joining the two ends of the strip of metal sheet 91 in the width direction. In other words, the forming rollers 82-85 form the strip of metal sheet 91 into a tubular section 92 having the shape of a circular pipe. The welding apparatus 8 welds the ends of the strip of metal sheet 91, which were originally the two ends in the width direction of the strip of metal sheet 91, together, after the strip of metal sheet 91 has been formed into a tubular section 92. As a result, the welding apparatus 8 manufactures a welded pipe 93.

[0084] Furthermore, when the welding apparatus 8 manufactures the welded pipe 93 shown in Figure 11, the welding defect detection device 1 according to Embodiment 3 is preferably attached to the welding apparatus 8. For example, the temperature sensor 10 is preferably provided inside the vacuum chamber 81 and near the forming rollers 82-85. The temperature sensor 10 is preferably capable of measuring the temperature of the welded area of ​​the welded pipe 93 immediately after welding. In this case, the welding defect detection device 1 can more accurately detect the occurrence of blowholes at the welded area of ​​the welded pipe 93.

[0085] As described above, the welding defect detection device 1 according to Embodiment 3 is incorporated into an electron beam welding apparatus 8. The welding defect detection device 1 can detect blowholes at the weld simply by having the temperature sensor 10 measure the temperature of the weld. For this reason, the welding defect detection device 1 is not complex in its configuration and is easy to install. For example, the welding defect detection device 1 can be incorporated into the welding apparatus 8 simply by providing the temperature sensor 10 inside or outside the vacuum chamber 81. In this way, the welding defect detection device 1 is easy to install into the welding apparatus 8.

[0086] The welding apparatus 8 shown in Figure 10 has only one vacuum chamber 81. The welding apparatus 8 shown in Figure 11 has vacuum chambers 86 and 87 adjacent to the inlet and outlet of the vacuum chamber 81, respectively, in order to maintain the vacuum level of the vacuum chamber 81 where welding takes place. Thus, the number of vacuum chambers 81, 86, and 87 in the welding apparatus 8 is arbitrary. The welding apparatus 8 is also an example of an electron beam welding apparatus as referred to in this disclosure.

[0087] (Embodiment 4) In the welding defect detection device 1 according to Embodiments 1-3, the controller 30 determines the presence or absence of blowholes using the temperature of the part of the workpiece immediately after welding, as measured by the temperature sensor 10. However, the welding defect detection device 1 is not limited to this. In addition to the temperature sensor 10, the welding defect detection device 1 may also include other sensors and use the measurement results of the other sensors to detect welding defects other than blowholes.

[0088] The welding defect detection device 1 according to Embodiment 4 further includes a displacement sensor that measures the surface shape of the welded portion within the welded area. The welding defect detection device 1 then determines the presence or absence of an undercut, which is a welding defect, from the side-system results of the displacement sensor. The welding defect detection device 1 according to Embodiment 4 will be described below with reference to Figures 12 and 13. Embodiment 4 will be described in a configuration that differs from Embodiments 1-3.

[0089] Figure 12 is a block diagram of the welding defect detection device 1 according to Embodiment 4. Figure 13 is a conceptual diagram of the displacement sensor 11 included in the welding defect detection device 1.

[0090] As shown in Figure 12, the welding defect detection device 1 includes a displacement sensor 11 in addition to the configuration described in Embodiment 1.

[0091] In Embodiment 4, the workpiece to be welded is a tubular-shaped strip of metal 91, or tubular portion 92, as described in Embodiments 2 and 3. The welding apparatus 2 then welds the opposing ends of the tubular portion 92 together. In this way, the welding apparatus 2 manufactures the welded pipe 93 shown in Figure 13.

[0092] The displacement sensor 11 measures the surface shape of the welded area 94 of the welded pipe 93 after welding by the welding device 2.

[0093] To describe the configuration of the displacement sensor 11 in detail, the displacement sensor 11 is composed of a sensor that measures the distance to an object. Specifically, the displacement sensor 11 is composed of a laser displacement sensor that irradiates an object with laser light and measures the distance from the reflected light to the object. The displacement sensor 11 has a lens (not shown) that spreads the laser light into a band shape and irradiates the object with this lens. As a result, the displacement sensor 11 measures the surface shape of each part of the object within the area irradiated by the band of laser light. In this way, the displacement sensor 11 measures the surface shape of the object, expressed in PQ coordinates, where the direction of extension of the laser light band is the P axis and the direction from the displacement sensor 11 to the object irradiated with laser light is the Q axis.

[0094] The displacement sensor 11, configured in this way, is positioned opposite the side surface of the welded pipe 93, as shown in Figure 13, in order to detect specific shapes caused by welding defects in the welded pipe 93. More specifically, the displacement sensor 11 is positioned opposite the welded portion 94 in order to measure the surface shape of the welded portion 94. The displacement sensor 11 is capable of emitting the aforementioned band-shaped laser light perpendicular to the pipe axis of the welded pipe 93. As a result, the displacement sensor 11 can measure the surface shape of the welded portion 94 in a direction perpendicular to the pipe axis of the welded pipe 93. Furthermore, as shown in Figure 12, the displacement sensor 11 is positioned downstream of the welding apparatus 2 and the temperature sensor 10, i.e., on the side indicated by arrow A. This allows the displacement sensor 11 to measure the surface shape of the welded portion 94 that has been partially solidified by the welding apparatus 2.

[0095] The displacement sensor 11 measures the surface shape of the welded portion 94 by receiving a measurement command from the controller 30, which is received by the temperature sensor 10 described in Embodiment 1. The displacement sensor 11 then transmits the measured surface shape data to the controller 30.

[0096] When the controller 30 receives surface shape data measured from the displacement sensor 11, it determines from the surface shape data whether or not there is an undercut, which is a type of welding defect, in the welded joint 94.

[0097] Here, undercut refers to the groove at the toe of a weld, as defined in Japanese Industrial Standard Z3001-4:2013, which is created by welding onto a base material or a previously welded surface. In Embodiment 4, undercut refers to the recess that occurs in the welded portion 94.

[0098] To explain in detail how the controller 30 determines the presence or absence of an undercut, the storage device 20 shown in Figure 12 stores data for the reference shape of the surface of the welded joint 94, which is used to determine the presence or absence of an undercut. The controller 30 reads this reference shape data from the storage device 20. The controller 30 then determines that there is an undercut in the welded joint 94 if the shape identified from the surface shape data received from the displacement sensor 11 is recessed by a certain amount or more compared to the shape identified from the reference shape data read from the storage device 20. When the controller 30 determines that there is an undercut in the welded joint 94, it commands the marking device 40 to mark. The marking device 40 places a mark indicating the presence of an undercut near the location of the undercut. In this way, the controller 30 notifies the user of the welding defect detection device 1 that there is an undercut.

[0099] The determination of whether or not there is an undercut by the controller 30 is performed by the same flow as the determination of whether or not there is a blowhole by the controller 30 described in Embodiment 1. That is, the determination of whether or not there is an undercut is the same as the flow of the welding defect detection process shown in Figure 6, but with the following configurations replaced: (1) Replace the temperature sensor 10 in steps S2 and S3 with a displacement sensor 11. (2) Replace the reading of the previous temperature data from the storage device 20, the determination of the reference value, and the storage of the current temperature data in step S4 with the reading of the reference shape data of the surface of the welded part 94 from the storage device 20. (3) Replace the reference value in step S5 with the reference shape of the surface of the welded part 94. The determination of whether or not there is an undercut by the controller 30 is performed by this flow. For this reason, a detailed explanation of the flow is omitted in Embodiment 4.

[0100] As described above, the welding defect detection device 1 according to Embodiment 4 is equipped with a displacement sensor 11 that measures the surface shape of the welded portion 94, that is, the post-welded portion within the area to be welded. The controller 30 determines that there is an undercut in the post-welded portion of the workpiece if the shape measured by the displacement sensor 11 is recessed by a certain amount or more compared to the reference shape obtained from the storage device 20. In this way, the welding defect detection device 1 can easily detect undercuts, which are a type of welding defect, despite its simple configuration.

[0101] The welded portion 94 described above is an example of the post-welding portion of the workpiece as referred to in this disclosure. The displacement sensor 11 is an example of the first surface shape sensor as referred to in this disclosure.

[0102] (Embodiment 5) The welding defect detection device 1 according to Embodiment 2 is incorporated into the welding pipe 93 manufacturing device 6. The welding pipe 93 manufacturing device 6 may be equipped with a mechanism for detecting molding defects when forming the welding pipe 93.

[0103] In Embodiment 5, the welding pipe 93 manufacturing apparatus 6 is equipped with multiple sensors for detecting molding defects. The welding pipe 93 manufacturing apparatus 6 according to Embodiment 5 will be described below with reference to Figures 14-16. Embodiment 5 will be described in a configuration that differs from Embodiments 1-4.

[0104] Figure 14 is a block diagram of the welding pipe 93 manufacturing apparatus 6 according to Embodiment 5. Figure 15 is a conceptual diagram of the displacement sensors 12 and 13 provided in the welding pipe 93 manufacturing apparatus 6. Figure 16 is a conceptual diagram of other displacement sensors 14 and 15 provided in the welding pipe 93 manufacturing apparatus 6. Note that, for ease of understanding, Figure 14 shows only the configuration of the welding pipe 93 manufacturing apparatus 6 that is connected to the controller 30.

[0105] As shown in Figure 14, the welding pipe manufacturing apparatus 6 is equipped with displacement sensors 12-15 connected to the controller 30 for detecting molding defects.

[0106] The displacement sensors 12 and 13 are sensors for detecting wear on the outer circumference of the first rolls 635 and 645, which have grooves formed on their outer circumference, among the first rolls 635 and 645 and second rolls 636 and 646 shown in Figure 15, which are provided in the marking machines 63 and 64 described in Embodiment 2.

[0107] Displacement sensors 12 and 13 are positioned opposite the outer periphery of the first rolls 635 and 645, respectively, as shown in Figure 15, in order to detect wear on the outer periphery of the first rolls 635 and 645. Similar to the displacement sensor 11 described in Embodiment 4, each of the displacement sensors 12 and 13 emits a band of laser light to measure the surface shape of an object represented by a PQ coordinate system, where the direction of the laser beam's extension is the P axis and the direction from the displacement sensor 11 to the object irradiated by the laser light is the Q axis. Each of the displacement sensors 12 and 13 directs the direction of its laser beam parallel to the central axis C1 of the first rolls 635 and 645. This allows each of the displacement sensors 12 and 13 to measure the surface shape of the outer periphery of the first rolls 635 and 645 in a direction parallel to the central axis C1.

[0108] In contrast, the displacement sensors 14 and 15 are sensors provided in the molding apparatus 65 described in Embodiment 2, for detecting wear on the outer circumference of the molding rolls 651 and 652 shown in Figure 16.

[0109] As shown in Figure 16, the forming roll 651 has a convex outer circumference that protrudes radially and outward. On the other hand, the forming roll 652 has a concave outer circumference that is recessed in the direction of the central axis C3. The forming rolls 651 and 652 rotate with a strip of metal 91, which extends tangentially to the forming rolls 651 and 652, sandwiched between them. As a result, the forming rolls 651 and 652 curve the strip of metal 91 in the width direction of the strip, forming the strip of metal 91 into a tubular shape.

[0110] Displacement sensor 14 is positioned opposite the outer periphery of the forming roll 651, one of the forming rolls 651 and 652. Displacement sensor 15 is positioned opposite the outer periphery of the forming roll 652. Like displacement sensors 11-13, displacement sensors 14 and 15 emit a band of laser light to measure the surface shape of an object represented by the PQ coordinates described above. Displacement sensors 14 and 15 each direct the direction of their laser beam band parallel to the central axis C2 of the forming roll 651 and the central axis C3 of the forming roll 652, respectively. As a result, displacement sensor 14 can measure the surface shape of the outer periphery of the forming roll 651 in a direction parallel to the central axis C2. Displacement sensor 15 can measure the surface shape of the outer periphery of the forming roll 652 in a direction parallel to the central axis C3.

[0111] Returning to Figure 14, the displacement sensors 12-15 measure the surface shape of the first rolls 635, 645 and the forming rolls 651, 652 upon receiving a measurement command from the controller 30. The controller 30 issues measurement commands at short intervals, causing the displacement sensors 12-15 to measure the surface shape of the first rolls 635, 645 and the forming rolls 651, 652 multiple times before they complete one rotation. As a result, the controller 30 causes the displacement sensors 12-15 to measure the surface shape over the entire circumferential direction of the first rolls 635, 645 and the forming rolls 651, 652. The displacement sensors 12-15 transmit the measured surface shape data to the controller 30.

[0112] Each time the controller 30 receives surface shape data from each of the displacement sensors 12-15, it determines from the received surface shape data whether the first rolls 635, 645 and the forming rolls 651, 652 have worn to an unacceptable degree.

[0113] In detail, the storage device 20 stores reference roll shape data corresponding to each of the first rolls 635, 645 and the forming rolls 651, 652. Each time the controller 30 receives surface shape data from each of the displacement sensors 12-15, it reads the reference roll shape data for the first rolls 635, 645 and the forming rolls 651, 652 corresponding to the received surface shape data from the storage device 20. The controller 30 then determines that the first rolls 635, 645 and the forming rolls 651, 652 corresponding to the received surface shape data are worn to an unacceptable degree if the shape identified from the received surface shape data is worn by a certain amount or more than the shape identified from the reference roll shape data read from the storage device 20. The controller 30 then determines that the corresponding first rolls 635, 645 and the forming rolls 651, 652 should be replaced. For example, if the average surface position calculated from the received surface shape data is more than a certain value away from the average surface position calculated from the reference roll shape data, the controller 30 determines that the corresponding first rolls 635, 645 and forming rolls 651, 652 are worn to an unacceptable degree, and further determines that the corresponding first rolls 635, 645 and forming rolls 651, 652 should be replaced.

[0114] In Embodiment 5, the welding defect detection device 1 is equipped with a display device 50. When the controller 30 determines that the corresponding first rolls 635, 645 and forming rolls 651, 652 should be replaced, it displays on the display device 50 that the corresponding first rolls 635, 645 and forming rolls 651, 652 have reached the time for replacement. In this way, the controller 30 prompts the user to replace the corresponding first rolls 635, 645 and forming rolls 651, 652.

[0115] As described above, the welding pipe manufacturing apparatus 6 according to Embodiment 5 is equipped with displacement sensors 12 and 13 that measure the surface shape of the first rolls 635 and 645 of the marking machines 63 and 64. The controller 30 determines that the first rolls 635 and 645 should be replaced if the shape measured by the displacement sensors 12 and 13 is worn by a certain amount or more compared to the standard roll shape of the first rolls 635 and 645 obtained from the storage device 20. In this way, despite its simple configuration, the welding defect detection device 1 can easily determine when the first rolls 635 and 645 of the marking machines 63 and 64 should be replaced.

[0116] Furthermore, the welding pipe manufacturing apparatus 6 according to Embodiment 5 is equipped with displacement sensors 14 and 15 that measure the surface shape of the forming rolls 651 and 652 of the forming apparatus 65. The controller 30 determines that the forming rolls 651 and 652 should be replaced if the shape measured by the displacement sensors 14 and 15 is worn by a certain amount or more compared to the standard roll shape of the forming rolls 651 and 652 obtained from the storage device 20. In this way, despite its simple configuration, the welding defect detection device 1 can easily determine when the forming rolls 651 and 652 of the forming apparatus 65 need to be replaced.

[0117] Furthermore, the first rolls 635 and 645 of the marking machines 63 and 64 described above are examples of groove-forming rolls that form grooves on the surface of a strip of metal sheet to form the inner wall of a tubular section, as referred to in this disclosure. The displacement sensors 12 and 13 are examples of second surface shape sensors as referred to in this disclosure. Also, the forming rolls 651 and 652 of the forming apparatus 65 are examples of forming rolls that curve the strip of metal sheet in the width direction, thereby bringing the first and second end faces in the width direction closer together. The displacement sensors 14 and 15 are examples of third surface shape sensors as referred to in this disclosure. Moreover, the reference roll shape corresponding to the first rolls 635 and 645 of the data stored in the storage device 20 is an example of a reference groove-forming roll shape as referred to in this disclosure. The reference roll shape corresponding to the forming rolls 651 and 652 of the data stored in the storage device 20 is an example of a reference forming roll shape as referred to in this disclosure.

[0118] The welding defect detection device 1, welding system, welding pipe 93 manufacturing apparatus 6, welding defect detection method, welding workpiece manufacturing method, and program according to embodiments of the present disclosure have been described above. However, the welding defect detection device 1, welding system, welding pipe 93 manufacturing apparatus 6, welding defect detection method, and program are not limited thereto.

[0119] For example, in Embodiments 1-5, the welding defect detection device 1 is used to detect blowholes in the welding of flat metal plates 3 and 4 or in the welding of a tubular strip-shaped metal plate 91. However, the shape of the workpiece is not limited to this. The workpiece only needs to have a linear welding area. The shape of the workpiece is arbitrary to this extent. For example, the workpiece may be a circular pipe, a square pipe, a columnar body, etc.

[0120] Furthermore, in Embodiments 1-5, a metal composite is manufactured by welding the joint surfaces of flat metal plates 3 and 4, or a welded pipe is manufactured by welding a strip-shaped metal plate 91 formed into a tubular shape. However, the products manufactured by welding, i.e., the workpieces to be welded, are not limited to these. In addition to metal composites and welded pipes, the workpieces to be welded may also be tanks, such as hot water storage tanks. Alternatively, the workpieces to be welded may be heat transfer pipes, such as flat pipes. Therefore, the method for manufacturing workpieces to be welded, which comprises the welding process performed by welding devices 2, 7, and 8 described in Embodiments 1-5 and the welding defect detection process performed by the welding defect detection device 1, is applicable to the manufacture of tanks and heat transfer pipes in addition to metal composites and welded pipes. This method for manufacturing workpieces to be welded is applicable to the general manufacture of workpieces in which linear welding points are welded by moving the welding device relative to the workpiece.

[0121] Furthermore, in Embodiments 1-5, the temperature sensor 10 is a two-color thermometer. However, the temperature sensor 10 is not limited to this. The temperature sensor 10 only needs to measure the temperature of the portion immediately after welding within the welded area each time the welding apparatus 2, 7, and 8 move, which weld linear welded areas on the workpiece by moving relative to the workpiece. Here, each time the welding apparatus 2, 7, and 8 move may be, for example, each time the welding apparatus 2, 7, and 8 move a certain distance, or each time a certain amount of time has elapsed while the welding apparatus 2, 7, and 8 are moving relative to each other. Therefore, the type of temperature sensor 10 is arbitrary as long as it satisfies this condition. The temperature sensor 10 may be, for example, a monocolor thermometer. Also, the temperature sensor 10 may be a non-contact thermometer other than a two-color thermometer or a monocolor thermometer.

[0122] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure.

[0123] This application is based on Japanese Patent Application No. 2024-164895, filed on 24 September 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-164895 are incorporated herein by reference.

[0124] 1 Welding defect detection device, 2, 7, 8 Welding equipment, 3, 4 Metal plate, 5 Conveying device, 6 Welded pipe manufacturing equipment, 10 Temperature sensor, 11-15 Displacement sensor, 20 Storage device, 30 Controller, 31 Processor, 32 Memory, 33 Network interface, 34 Bus, 40 Marking device, 50 Display device, 60 Uncoiler, 61 Strip joining, 62 Accumulator, 63, 64 Engraving machine, 65 Forming device, 66 Drawing machine, 67 Cutting machine, 68 Recoiler, 81 Vacuum chamber, 82-85 Forming roller, 86, 87 Vacuum chamber, 91 Strip metal plate, 92 Tubular section, 93 Welded pipe, 94 Welded section, 100 Welding system, 601 Holder, 631-633 Dancer roll, 635, 645 First roll, 636, 646 Second roll, 651, 652; forming roll, 671; cutter, 681; winding section, A arrow, C1-C3 central axis.

Claims

1. A welding defect detection device comprising: a temperature sensor that measures the temperature of the portion immediately after welding within the welded area of ​​a workpiece each time a welding device moves relative to the workpiece, which welds linear welded areas of the workpiece; and a controller that determines that there is a blowhole in the portion immediately after welding when the temperature of the portion immediately after welding measured by the temperature sensor is higher than a certain value or more than a reference value.

2. The welding defect detection device according to claim 1, further comprising a storage device that stores data of the temperature of the portion immediately after welding measured by the temperature sensor each time the welding device moves, wherein the controller stores the temperature data in the storage device each time the temperature sensor measures the temperature of the portion immediately after welding, and reads out the temperature data measured up to the previous time, and determines that there is a blowhole in the portion of the workpiece immediately after welding if the temperature data measured this time is higher than a certain value or more than the reference value obtained from the temperature data read out up to the previous time 3. The welding defect detection device according to claim 1 or 2, wherein the reference value is the temperature of the portion immediately after welding measured by the temperature sensor prior to the temperature of the portion immediately after welding measured by the temperature sensor.

4. The welding defect detection device according to claim 1 or 2, wherein the reference value is the average value obtained from the temperatures of the portion immediately after welding measured by the temperature sensor prior to the temperature of the portion immediately after welding measured by the temperature sensor.

5. The welding defect detection device according to any one of claims 1 to 4, further comprising a marking device that marks the portion immediately after welding or its vicinity when the controller determines that there is a blowhole in the portion immediately after welding.

6. The welding defect detection device according to any one of claims 1 to 5, further comprising a first surface shape sensor for measuring the surface shape of the welded portion within the welded area, wherein the controller determines that there is an undercut in the welded portion of the workpiece when the shape measured by the first surface shape sensor is recessed by a certain amount or more compared to a reference shape.

7. A welding system comprising: a welding device that welds linear weld locations on a workpiece by moving relative to the workpiece; a temperature sensor that measures the temperature of the portion immediately after welding within the weld location each time the welding device moves; and a controller that determines that there is a blowhole in the portion immediately after welding when the temperature of the portion immediately after welding measured by the temperature sensor is higher than a certain value or more than a reference value.

8. A welding system according to claim 7, and a forming device that feeds a strip of metal sheet curved in the width direction in the direction of extension of the strip, and brings together the first end face and the second end face in the width direction of the portion of the strip of metal sheet on the feeding direction side, thereby forming the portion of the strip of metal sheet on the feeding direction side into a tubular shape which is the work to be welded, wherein the welding device welds the opposing first end face and the second end face of the formed tubular shape, and the temperature sensor measures the temperature of the joint between the opposing first end face and the second end face immediately after welding by the welding device, a welded pipe manufacturing device.

9. The welding apparatus is an electron beam welding apparatus, as described in claim 8, for manufacturing welded pipes.

10. The apparatus for manufacturing a welded pipe according to claim 8 or 9, further comprising a vacuum chamber housing the molding apparatus and the temperature sensor.

11. A welding pipe manufacturing apparatus according to any one of claims 8 to 10, further comprising a second surface shape sensor for measuring the surface shape of the molding apparatus, wherein the molding apparatus has a molding roll that curves the strip-shaped metal plate in the width direction, thereby bringing the first end face and the second end face in the width direction closer together, the second surface shape sensor measures the surface shape of the molding roll, and the controller determines that the molding roll should be replaced if the shape measured by the second surface shape sensor is worn by more than a certain amount from a reference molding roll shape.

12. A welding pipe manufacturing apparatus according to any one of claims 8 to 11, further comprising: a groove-forming roll for forming grooves on the surface of the strip-shaped metal plate for forming the inner wall of the tubular portion; and a third surface shape sensor for measuring the surface shape of the groove-forming roll, wherein the controller determines that the groove-forming roll should be replaced if the shape measured by the third surface shape sensor is worn by more than a certain amount from the standard groove-forming roll shape.

13. A method for detecting welding defects in a welding apparatus that welds linear weld locations on a workpiece by moving relative to the workpiece, comprising: measuring the temperature of a portion of the workpiece immediately after welding each time the welding apparatus moves; and determining that there is a blowhole in the portion immediately after welding if the measured temperature of the portion immediately after welding is higher than a certain value or more than a reference value.

14. A method for manufacturing a workpiece, comprising the steps of: welding a linear welding location on a workpiece by moving a welding device relative to the workpiece; and detecting a welding defect as described in claim 13.

15. A program to cause a computer that detects welding defects in the area immediately after welding based on the temperature data measured by the temperature sensor to be detected each time the temperature sensor measures the temperature of the area immediately after welding, to be used when a welding device moves relative to the workpiece to weld a linear welding area of ​​the workpiece. The program to perform the following steps: acquire the measured temperature data each time the temperature sensor measures the temperature of the area immediately after welding; and determine that there is a blowhole in the area immediately after welding if the measured temperature of the area immediately after welding is higher than a certain value or more than a reference value.

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