Welded pipe manufacturing method and welded pipe manufacturing device

Abstract

This welded tube manufacturing method comprises a step for fabricating a welded tube. In the step for fabricating a welded tube, a band-shaped metal plate (2) having a first end face and a second end face on the opposite side to the first end face in the width direction thereof is curved in the width direction into a tubular form, thereby forming a tubular body (3) with the first end face and the second end face facing each other, and then the first end face and the second end face are welded together by impinging an electronic beam thereon, thereby fabricating a welded tube.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a welded pipe. and Welded pipe manufacturing equipment Place Regarding. [Background technology]

[0002] Welded pipes are manufactured by bending a strip of metal sheet widthwise into a tubular shape and welding both ends of the bent pipe together. If the welded portion of such a welded pipe oxidizes, the strength of the welded pipe itself will decrease. Therefore, a method for manufacturing welded pipes that suppresses oxidation of the welded portion has been developed.

[0003] For example, Patent Document 1 discloses a method for manufacturing a welded pipe in which a strip-shaped metal plate is bent in the width direction, and both ends in the width direction are joined to form a tubular body, and the joined ends are welded while supplying a shielding gas into the internal space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-271790 Summary of the Invention [Problem to be solved by the invention]

[0005] In the method for manufacturing a welded pipe described in Patent Document 1, an inert gas is used as a shielding gas. This inert gas is a special gas. Therefore, preparing the shielding gas and performing the welding operation are not easy.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a method and an apparatus for manufacturing a welded pipe that can suppress oxidation of a welded portion without using an inert gas. [Means for solving the problem]

[0007] In order to achieve the above object, the method for manufacturing a welded pipe according to the present disclosure is ,band shaped metal plate but The metal strip is bent in a tubular shape in the width direction, and a first end face in the width direction of the metal strip faces a second end face opposite the first end face. Pipe First end surface and second end surface of the shaped body Toni By applying an electron beam to the first end surface and the second end surface, the first end surface and the second end surface are welded together. , melt Process for manufacturing the pipe sleeve of Then, the welded pipe is manufactured. The extent , The method includes a step of causing electrons to collide with a gas in another space that is in communication with the space where the electron beam is collided with the first end surface and the second end surface, causing the gas to emit light, measuring the spectrum of the emitted light to determine the pressure of the gas, thereby determining the degree of vacuum in the space where the electron beam is collided, and determining the presence or absence of a welding defect based on the determined degree of vacuum. . [Effects of the Invention]

[0008] According to the configuration of the present disclosure, in the process of producing a welded pipe, an electron beam is applied to a first end face and a second end face of a tubular body to weld the first end face and the second end face together, thereby producing a welded pipe. As a result, the welded portion where the first end face and the second end face are welded together is less likely to oxidize. According to the configuration of the present disclosure, oxidation of the welded portion can be suppressed without using an inert gas. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view of a front half of a welded pipe manufacturing apparatus according to an embodiment of the present disclosure; [Figure 2] 1 is a side view of a rear half of a welded pipe manufacturing apparatus according to an embodiment of the present disclosure; [Figure 3A] FIG. 1 is a top view showing an example of a band-shaped metal plate formed by a stamping machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure. [Figure 3B] FIG. 10 is a top view showing another example of a band-shaped metal plate formed by the stamping machine included in the welded pipe manufacturing apparatus according to the embodiment of the present disclosure. [Figure 3C] FIG. 10 is a top view showing yet another example of a band-shaped metal plate formed by a stamping machine included in the welded pipe manufacturing apparatus according to the embodiment of the present disclosure. [Figure 4] 1 is a cross-sectional view of a forming machine and a welding machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure. [Figure 5A]1 is a cross-sectional view of a breakdown roll of a forming machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure and a strip metal plate formed by the breakdown roll; [Figure 5B] 1 is a cross-sectional view of a breakdown roll of a forming machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure and a strip metal plate formed by the breakdown roll; [Figure 5C] 1 is a cross-sectional view of a breakdown roll of a forming machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure and a strip metal plate formed by the breakdown roll; [Figure 6A] 1 is a cross-sectional view of a fin pass roll of a forming machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure and a strip metal plate formed by the fin pass roll; [Figure 6B] 1 is a cross-sectional view of a fin pass roll of a forming machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure and a strip metal plate formed by the fin pass roll; [Figure 6C] 1 is a cross-sectional view of a tubular body finally formed by a forming machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure. [Figure 7] 1 is a cross-sectional view of a modified example of a forming machine and a welding machine included in a welded pipe manufacturing apparatus according to an embodiment of the present disclosure. [Figure 8] 10 is a cross-sectional view of another modified example of the forming machine and the welding machine included in the welded pipe manufacturing apparatus according to the embodiment of the present disclosure. [Figure 9] 10 is a cross-sectional view of yet another modified example of a forming machine and a welding machine included in the welded pipe manufacturing apparatus according to the embodiment of the present disclosure. [Figure 10] 1 is a cross-sectional view of a modified example of a welded pipe manufacturing apparatus according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a method for manufacturing a welded pipe according to an embodiment of the present disclosure will be described. and Welded pipe manufacturing equipment PlaceThis 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. In the Cartesian coordinate system XYZ shown in the drawings, when the upstream and downstream directions of the welded pipe manufacturing device are oriented horizontally, the vertical direction is the Z-axis, the horizontal directions of the upstream and downstream directions are the X-axis, and the direction perpendicular to the Z-axis and X-axis is the Y-axis.

[0011] (Embodiment) The welded pipe manufacturing apparatus according to the embodiment is an apparatus for manufacturing welded pipe from a strip metal plate. This manufacturing apparatus manufactures the welded pipe by welding the seam of a tubular body formed by bending a strip metal plate in the width direction. The welding is performed by applying an electron beam to the seam in a vacuum to suppress oxidation of the welded portion. The configuration of this manufacturing apparatus will be described below using an example in which the welded pipe to be manufactured is a heat transfer tube used in a heat exchanger. First, the overall configuration of this manufacturing apparatus will be described with reference to Figures 1, 2, 3A, 3B, and 3C.

[0012] Fig. 1 is a side view of the front half of a welded pipe manufacturing apparatus 1 according to an embodiment of the present invention, and Fig. 2 is a side view of the rear half of the manufacturing apparatus 1.

[0013] As shown in FIGS. 1 and 2, the welded pipe manufacturing apparatus 1 includes an uncoiler 10, a splicing machine 11, an accumulator 12, stamping machines 13 and 14, a forming machine 15, a welding machine 16, a drawing machine 17, a cutting machine 18, and a recoiler 19.

[0014] A strip metal sheet wound into a coil is supplied to a welded pipe manufacturing apparatus 1. The manufacturing apparatus 1 then manufactures a welded pipe from the strip metal sheet. An uncoiler 10 shown in Fig. 1 unwinds the coil around which the strip metal sheet is wound, and pulls out one end of the strip metal sheet from the coil.

[0015] In more detail, the uncoiler 10 has a cylindrical holder 111 that holds the coil of strip metal sheet from the inside, and a drive unit (not shown) that rotates the holder 111. The drive unit (not shown) rotates the holder 111 in the direction opposite to the winding direction of the coil. This causes the uncoiler 10 to pull out one end of the strip metal sheet from the coil. The uncoiler 10 supplies the pulled out end of the strip metal sheet to the splicing machine 11.

[0016] The splicing machine 11 connects the other end of one strip metal plate to one end of another strip metal plate. More specifically, in the uncoiler 10, although not shown, when the strip metal plate is completely unwound from the coil, the next coil is set and one end of the strip metal plate is unwound from that next coil. The splicing machine 11 connects the other end of the strip metal plate of the previous coil, which is opposite to the one end of the strip metal plate, to one end of the unwound strip metal plate of the next coil.

[0017] To explain its configuration, the joining machine 11 has a welding machine (not shown). The joining machine 11 uses the welding machine to weld the other end of the strip metal plate of the previous coil to one end of the strip metal plate of the next coil. The joining machine is also called a strip joining machine.

[0018] Meanwhile, the accumulator 12 stores a fixed length of the strip metal sheet unwound from the coil. More specifically, the accumulator 12 is equipped with a roller (not shown). The middle portion of the strip metal sheet unwound from the coil is hung on the roller. The roller then winds up the middle portion of the strip metal sheet by a fixed length that should be supplied during the welding time of the splicing machine 11 to prevent the supply of the strip metal sheet from being stopped while the splicing machine 11 is welding. In this way, the accumulator 12 retains the strip metal sheet for a fixed length. After winding up the middle portion of the strip metal sheet by a fixed length, the accumulator 12 sends one end portion of the strip metal sheet, i.e., the +X end portion in the Cartesian coordinate system XYZ shown in FIG. 1 , to the stamping machine 13.

[0019] The stamping machines 13 and 14 are used to form grooves on the inner wall of the welded pipe to be manufactured; more specifically, 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.

[0020] Specifically, the stamping machines 13 and 14 each have a first roll (not shown) called a groove roll, or abbreviated as a G roll, which has a groove formed on its outer periphery, and a second roll (not shown) whose outer periphery is smooth and curved, without any irregularities. The stamping machine 13 sandwiches the metal strip fed from the accumulator 12, whose tension has been adjusted by the dancer rolls 131 and 132 shown in FIG. 1, between the first and second rolls. The stamping machine 13 passes the metal strip between the first and second rolls while pressing the first and second rolls against the metal strip. This allows the stamping machine 13 to form a groove in the metal strip.

[0021] In contrast, the stamping machine 14 has a third roll whose outer periphery has grooves of a different shape than the grooves of the first roll, and a fourth roll whose outer periphery is smooth and curved, without any irregularities. The stamping machine 14 sandwiches the metal strip, in which grooves have been formed by the stamping machine 13 and whose tension has been adjusted by dancer rolls 132 and 133, between the third and fourth rolls. The stamping machine 14 also presses the third and fourth rolls against the metal strip. The stamping machine 14 then passes the metal strip between the third and fourth rolls. This allows the stamping machine 14 to form grooves in the metal strip that are different from those formed by the stamping machine 13.

[0022] The stamping machines 13 and 14 perform the above-described processing on the strip metal plate to form a plurality of grooves of different shapes in the strip metal plate. Examples of strip metal plates with such grooves formed are shown in Figures 3A, 3B, and 3C.

[0023] Fig. 3A is a top view showing an example of a band-shaped metal plate 2 formed by the stamping machines 13 and 14 provided in the welded pipe manufacturing apparatus 1. Fig. 3B is a top view showing another example of the band-shaped metal plate 2. Fig. 3C is a top view showing yet another example of the band-shaped metal plate 2.

[0024] For example, as shown in FIG. 3A, the stamping machines 13 and 14 form herringbone-shaped grooves in the metal strip 2, in which multiple V-shaped grooves are arranged in the extending direction of the metal strip 2. Alternatively, as shown in FIG. 3B, the stamping machines 13 and 14 form multiple X-shaped grooves in the metal strip 2. Alternatively, as shown in FIG. 3C, the stamping machines 13 and 14 form grooves inclined with respect to the extending direction of the metal strip 2 and embossments that are circular in top view in the metal strip 2. By forming such grooves in the metal strip 2, the stamping machines 13 and 14 improve the heat exchange efficiency of the welded pipe when the manufactured welded pipe is used as a heat transfer tube for a heat exchanger. After forming such grooves in the metal strip 2, the stamping machines 13 and 14 send the grooved portion to the forming machine 15 and welding machine 16 shown in FIG. 2.

[0025] The detailed configurations of the forming machine 15 and the welding machine 16 will be described later, but to briefly explain their functions, the forming machine 15 bends the metal strip 2 into a tubular shape, for example a circular pipe shape, in the width direction of the strip, to form a tubular body having a shape where both ends in the width direction of the metal strip 2, i.e., the +Y end and the -Y end, come together. Specifically, the forming machine 15 is equipped with a breakdown roll and a fin pass roll, which will be described later. The forming machine 15 then uses these rolls to form a tubular body where the +Y end and the -Y end come together on the +X end side of the metal strip 2.

[0026] Meanwhile, the welding machine 16 welds the joints of the tubular bodies. The welding machine 16 is equipped with an electron beam welding machine, which will be described later, and uses the electron beam welding machine to weld the joints of the tubular bodies to produce a welded pipe portion on the +X end side of the metal strip 2. Then, the welding machine 16 sends the welded pipe portion of the metal strip 2 to the drawing machine 17.

[0027] The drawing machine 17 adjusts the outer diameter and inner diameter of the welded pipe portion produced by the welding machine 16. Although not shown, the drawing machine 17 is equipped with a die having a through hole that is smaller than the outer diameter of the welded pipe produced by the welding machine 16 and has the same diameter as the target outer diameter. The drawing machine 17 passes the welded pipe portion of the strip metal plate 2 through the die and pulls the welded pipe portion out of the die. In this way, the drawing machine 17 processes the welded pipe portion of the strip metal plate 2 to have an outer diameter that is the same as the diameter of the through hole in the die. The drawing machine 17 sends the processed welded pipe portion of the strip metal plate 2 to a cutting machine 18 shown in FIG. 2.

[0028] The cutting machine 18 is equipped with a cutter 181 that is movable in the direction from the front to the back in Figure 2, i.e., in the Y direction. The cutting machine 18 moves the cutter 181 to cut the welded pipe portion of the strip metal plate 2 that has been processed by the drawing machine 17 to a desired length. In this way, the cutting machine 18 produces a welded pipe of the desired length. The cutting machine 18 then sends the welded pipe cut to the desired length to the recoiler 19.

[0029] The recoiler 19 has a cylindrical winding section 191, and winds the welded pipe cut to the desired length by the cutter 18 onto the winding section 191 to form a coil again. In this way, the recoiler 19 prepares the welded pipe so that it can be supplied to an external device.

[0030] The coil-shaped metal strip 2 loaded on the uncoiler 10 is, for example, a rolled copper or copper alloy sheet. In this case, the tempering may be O-grade, 1 / 2H-grade, or 1 / 4H-grade as specified in JIS H3100. The width of the metal strip 2 may correspond to the outer diameter of the welded pipe before being reduced in diameter by the drawing machine 17. For example, if the outer diameter of the welded pipe before being reduced in diameter by the drawing machine 17 is 7 mm, the width of the metal strip 2 is 22.5 mm, which is the circumference calculated from the outer diameter plus a welding allowance of 0.5 mm. Assuming that the thickness of the metal strip 2 is reduced by 0.05 mm by the stamping machine 14, the thickness of the metal strip 2 may be 0.05 mm thicker than the thickness of the welded pipe before being reduced in diameter by the drawing machine 17.

[0031] As described above, in the welded pipe manufacturing apparatus 1, the uncoiler 10 pulls out the coiled metal strip 2, and the stamping machines 13 and 14 form grooves in the metal strip 2. Furthermore, the forming machine 15 bends the metal strip 2 into a tubular shape in the Y direction and aligns the +Y end and the -Y end of the metal strip 2. Then, the welding machine 16 welds the seam formed by aligning the +Y end and the -Y end of the metal strip 2, to produce a welded pipe.

[0032] In this case, the welding machine 16 is a common welding device such as high-frequency induction welding or TIG (Tungsten Insert Gas) welding, and if the welding atmosphere contains a large amount of oxygen, the welded joint will be oxidized, which will reduce the strength of the welded pipe produced.

[0033] On the other hand, to prevent oxidation of the weld, high-frequency induction welding or TIG welding equipment is sometimes equipped with a nozzle through which an inert gas shielding gas such as argon or helium is supplied. However, in this case, since the inert gas is a special gas, preparing and working with the inert gas is not easy. Furthermore, the installation of a gas supply facility makes the equipment structure complicated, and the equipment setup is cumbersome.

[0034] Therefore, in the welded pipe manufacturing apparatus 1, to suppress oxidation of the welded portion, the forming machine 15 and the welding machine 16 are equipped with vacuum chambers, and forming and welding are performed in the vacuum chambers. Next, the configurations of the forming machine 15 and the welding machine 16 will be described with reference to Figures 4, 5A-5C, and 6A-6C.

[0035] Fig. 4 is a cross-sectional view of the forming machine 15 and the welding machine 16 provided in the welded pipe manufacturing apparatus 1. Figs. 5A to 5C are cross-sectional views of breakdown rolls 30-35 provided in the forming machine 15 and the band-shaped metal sheet 2 formed by the breakdown rolls 30-35. Figs. 6A and 6B are cross-sectional views of fin pass rolls 36-39 provided in the forming machine 15 and the band-shaped metal sheet 2 formed by the fin pass rolls 36-39. Fig. 6C is a cross-sectional view of the tubular body 3 finally formed by the forming machine 15.

[0036] Although not shown in Figures 5A-5C, 6A and 6B, the surface of the strip metal plate 2 on which grooves are formed by the stamping machines 13 and 14 faces upward, i.e., toward the +Z side.

[0037] As shown in FIG. 4, the welded pipe manufacturing apparatus 1 includes vacuum chambers 20-22, breakdown rolls 30-35 and fin pass rolls 36-39 provided in the vacuum chamber 21, a vacuum chamber 40 provided above the vacuum chamber 21, and an electron beam welder 41 provided in the vacuum chamber 40.

[0038] The vacuum chambers 20-22, the breakdown rolls 30-35, and the fin pass rolls 36-39 are members that make up the forming machine 15. On the other hand, the vacuum chamber 40 and the electron beam welder 41 are members that make up the welding machine 16.

[0039] The vacuum chambers 20-22 are provided to maintain a vacuum level sufficient for electron beam welding. Specifically, the vacuum chambers 20-22 are arranged in the order of 20, 21, and 22 from the upstream side of the welded pipe manufacturing apparatus 1, i.e., from the -X side. The vacuum chambers 20-22 are adjacent to each other in the X direction. Furthermore, the vacuum chambers 20 and 22 on either side in the X direction are provided with transport rolls 23 and 24 for transporting the strip metal sheet 2 to be processed and the welded pipe portion after processing of the strip metal sheet 2. Furthermore, the vacuum chamber 21 located in the center in the X direction houses breakdown rolls 30-35 and fin pass rolls 36-39 that form the strip metal sheet 2 to be processed into the tubular body 3 to be welded. Furthermore, the vacuum chamber 21 is connected to a vacuum chamber 40 that houses an electron beam welder 41. These allow the forming and welding processes for the welded pipe manufacturing process to be performed inside the vacuum chamber 21.

[0040] The vacuum chamber 21 preferably has a larger volume than the vacuum chambers 20 and 22 in order to form and weld the strip metal plate 2 to be processed.

[0041] In vacuum chambers 20-22, in order to increase the degree of vacuum in vacuum chamber 21 located in the center in the X direction as mentioned above, vacuum chamber 21 is evacuated by a vacuum pump (not shown) that achieves a higher ultimate vacuum than the vacuum pump that evacuates vacuum chambers 20 and 22.

[0042] Specifically, each of the vacuum chambers 20-22 has an exhaust port (not shown), and each of these exhaust ports is connected to a vacuum pump (not shown). Of these vacuum pumps (not shown), the vacuum pumps connected to the exhaust ports of the vacuum chambers 20 and 22 are for low vacuum. Examples of such low vacuum pumps include mechanical pumps such as water jet pumps, reciprocating pumps, rotary pumps, and centrifugal pumps. In contrast, the vacuum pump connected to the exhaust port of the vacuum chamber 21 is for medium vacuum, such as a mechanical booster pump or turbomolecular pump. By connecting such vacuum pumps to the vacuum chambers 20-22, a structure is realized in which the high-vacuum vacuum chamber 21 is sandwiched between the low-vacuum vacuum chambers 20 and 22 on both sides in the X direction. For example, a structure is realized in which the vacuum chamber 21, with a pressure of 2.0 to 6.0 Pa, is sandwiched between the vacuum chambers 20 and 22, with a pressure of 50 to 800 Pa.

[0043] Note that medium vacuum refers to one of the vacuum classifications defined by the Japanese Industrial Standards, with a vacuum level of 0.1 to 100 Pa. Low vacuum refers to another of the vacuum classifications defined by the same standard, with a vacuum level of 100,000 to 100 Pa. In this specification, "in a vacuum" refers to a low vacuum or a vacuum with a higher vacuum level than a low vacuum. Furthermore, while vacuum chambers 20 and 22 are both in a low vacuum, the term "same vacuum level" as used here refers to the same vacuum classification.

[0044] Furthermore, the vacuum chamber 20 is provided with an inlet 201 and an outlet 202, as shown in FIG. 4, for supplying and discharging the strip metal plate 2 to be processed. The YZ cross-sectional shapes of the inlet 201 and the outlet 202 are larger than the YZ cross-sectional shape of the strip metal plate 2 to an extent that there is play. The strip metal plate 2 passes through the inlet 201 and the outlet 202. As a result, minute gaps 205 and 206 are formed between the inner walls of the inlet 201 and the outlet 202 and the strip metal plate 2, respectively, to an extent that the strip metal plate 2 can slide. Furthermore, the amount of air flowing into the vacuum chamber 20 from the outside is small, and as a result, a decrease in the degree of vacuum in the vacuum chamber 20 is suppressed.

[0045] Similarly, the vacuum chamber 21 is provided with an inlet 211 having the same shape and size as the outlet 202 of the vacuum chamber 20 for supplying the strip metal plate 2 to be processed. The inlet 211 is adjacent to and continuous with the outlet 202 in the X direction. As a result, the inlet 211 is in communication with the vacuum chamber 20. The strip metal plate 2 passes through the inlet 211. As a result, a minute gap 215 is formed between the inner wall of the inlet 211 and the strip metal plate 2 to allow the strip metal plate 2 to slide, and a decrease in the degree of vacuum in the vacuum chamber 21 is suppressed. In particular, because the inlet 211 is in communication with the low-vacuum vacuum chamber 20 located in the -X direction, the degree of vacuum in the vacuum chamber 21 is less likely to decrease than if the inlet 211 were directly connected to the outside space.

[0046] The vacuum chamber 21 is provided with an outlet 212 whose YZ cross-sectional shape is larger than the YZ cross-sectional shape of the welded pipe portion 4 to allow some play for discharging the welded pipe portion 4 of the strip metal plate 2 that has been formed and welded within the vacuum chamber 21. The welded pipe portion 4 formed on one end of the strip metal plate 2, i.e., on the +X end, passes through the outlet 212. This creates a minute gap 216 between the inner wall of the outlet 212 and the welded pipe portion 4 to allow sliding of the welded pipe portion 4, while suppressing a decrease in the degree of vacuum in the vacuum chamber 21. The outlet 212 is also connected to the low-vacuum vacuum chamber 22 via an inlet 221, which will be described later. This prevents the degree of vacuum in the vacuum chamber 21 from being suddenly reduced by the outlet 212.

[0047] Meanwhile, the vacuum chamber 22 is provided with an inlet 221 and an outlet 222 having the same shape and size as the outlet 212 of the vacuum chamber 21 to allow the welded pipe section 4 to pass through. The welded pipe section 4 that has passed through the outlet 212 of the vacuum chamber 21 passes through the inlet 221 and the outlet 222. As a result, minute gaps 225, 226 are formed between the inner walls of the inlet 221 and the outlet 222 and the welded pipe section 4, allowing the welded pipe section 4 to slide. Furthermore, the amount of air flowing into the vacuum chamber 22 from the outside is small, suppressing a decrease in the degree of vacuum in the vacuum chamber 22. Furthermore, the inlet 221 is adjacent to and continuous with the outlet 212 of the vacuum chamber 21 in the X direction. As a result, the degree of vacuum in the adjacent vacuum chamber 21 is less likely to decrease compared to when the adjacent vacuum chamber 21 is directly connected to the outside space.

[0048] The welded pipe portion 4 has a space in the center. Therefore, there is a possibility that air from outside the apparatus may flow into the vacuum chambers 21 and 22 through the interior of the welded pipe portion 4. Therefore, before operating the welded pipe manufacturing apparatus 1 to manufacture the welded pipe, a special setting is used in which the strip metal plate 2 to be processed is passed through the vacuum chambers 20-22. In this special setting, the welded pipe portion 4 is prepared on the +X end side of the strip metal plate 2, and the +X end of the welded pipe portion 4 is sealed. For example, a device for crushing the end of the pipe is provided in the +X side region of the vacuum chamber 21 relative to the location where the electron beam described below is applied to the tubular body 3, or in the vacuum chamber 22. This device crushes the +X end of the welded pipe portion 4. This prevents a decrease in the vacuum level in the vacuum chambers 21 and 22 due to the internal space of the welded pipe portion 4. The crushed +X end of the welded pipe portion 4 cannot be used as a welded pipe. Therefore, the +X end is preferably removed using the cutting machine 18 described above.

[0049] The vacuum chambers 20-22 are provided with the inlets 201, 211, and 221 and the outlets 202, 212, and 222, thereby maintaining a vacuum level. The vacuum chamber 21, which is located in the center in the X direction, has a higher vacuum level than the vacuum chambers 20 and 22 located on either side of the vacuum chamber 21 in the X direction, and the vacuum chamber 21 is maintained at a vacuum level that allows electron beam welding. In order to form the strip metal plate 2 into a weldable shape in the vacuum chamber 21, the vacuum chamber 21 is provided with the breakdown rolls 30-35 and fin pass rolls 36-39, as described above.

[0050] The breakdown rolls 30-35 are arranged above or below as shown in Figs. 5A to 5C, and the metal strip 2 is passed between them to roughly form the metal strip 2 into an arc-shaped cross section.

[0051] Specifically, breakdown rolls 30-35 are arranged in the following order from the upstream side, i.e., the -X side, shown in FIG. 4: breakdown rolls 30 and 31, 32 and 33, and 34 and 35. As shown in FIGS. 5A-5C , breakdown roll 30 having convex portions 301 protruding downward, i.e., protruding toward the -Z side, and breakdown roll 31 having concave portions 311 recessed toward the -Z side are arranged in the Z direction to form a pair. Also, breakdown roll 32 having convex portions 321 protruding toward the -Z side and breakdown roll 33 having concave portions 331 recessed toward the -Z side are arranged in the Z direction to form a pair. Furthermore, breakdown roll 34 having convex portions 341 protruding toward the -Z side and breakdown roll 35 having concave portions 351 recessed toward the -Z side are arranged in the Z direction to form a pair.

[0052] Furthermore, in the breakdown rolls 30, 32, and 34, the heights of the convex portions 301, 321, and 341 in the Z direction increase in the order of the convex portions 301, 321, and 341, in other words, in the order in which they are arranged downstream, i.e., toward the +X side. On the other hand, the widths of the convex portions 301, 321, and 341 in the Y direction decrease in the same order. The YZ cross-sectional shapes of the tips of the convex portions 301, 321, and 341 are rounded more in the same order.

[0053] In contrast, in breakdown rolls 31, 33, and 35, the Z-direction depths of recesses 311, 331, and 351 increase in the order in which breakdown rolls 31, 33, and 35 are arranged toward the +X side. Meanwhile, the Y-direction widths of recesses 311, 331, and 351 decrease in the same order. The YZ cross-sectional shapes of recesses 311, 331, and 351 become more curved and approach an arc shape in the same order.

[0054] The breakdown rolls 30-35 have such a shape, so that the metal strip 2 is curved more toward the +X side. As a result, the breakdown rolls 30-35 roughly form the metal strip 2 into the arc-shaped YZ cross section shown in Figures 5A to 5C. Note that the surface of the metal strip 2 on which the grooves are formed faces the inside of the arc-shaped YZ cross section.

[0055] On the other hand, as shown in Figures 6A and 6B, the fin pass rolls 36-39 are arranged in the Z direction and form pairs, similar to the breakdown rolls 30-35, but unlike the breakdown rolls 30-35, the strip metal sheet 2 is passed between the pair of rolls, thereby finishing and forming the strip metal sheet 2 into a circular shape when viewed in the YZ cross section.

[0056] In detail, as shown in Fig. 4, the fin pass rolls 36-39 are arranged in the order of fin pass rolls 36, 37, 38, and 39 from the -X side. As shown in Fig. 6A and 6B, the fin pass roll 36, which has a fin portion 361 formed in a recess that is recessed in an arc-shaped manner toward the +Z side in cross section and that protrudes toward the -Z side in a triangular shape in cross section, and the fin pass roll 37, which has a recess that is recessed in an arc-shaped manner toward the -Z side in cross section, are arranged in the Z direction to form a pair. Furthermore, the fin pass roll 38, which has a recess that is recessed in an arc-shaped manner toward the +Z side in cross section and that protrudes in a triangular shape toward the -Z side in cross section, and the fin pass roll 39, which has a recess that is recessed in an arc-shaped manner toward the -Z side in cross section, are arranged in the Z direction to form a pair.

[0057] Furthermore, in the fin pass rolls 36, 38, the width in the Y direction and the height in the Z direction of the fin portions 361, 381 decrease in the order of the fin portions 361, 381, in other words, in the order in which they are arranged toward the downstream side, i.e., the +X side. The recesses of the fin pass rolls 36, 38 and the recesses of the fin pass rolls 37, 39 face each other in the Z direction and form a space that is circular in cross section.

[0058] Because the fin pass rolls 36-39 have such a shape, they finish-form the metal strip 2 into a circular shape in YZ cross section in which the +Y end and the -Y end of the metal strip 2 approach each other toward the +X side. The fin pass rolls 36-39 ultimately form a tubular body 3 having a seam 5 in which the +Y end and the -Y end of the metal strip 2 face each other in a V-shape, as shown by the dotted line in Fig. 6C , that is, the ends of the metal strip 2 do not face each other in a V-shape, but rather the ends of the metal strip 2 face each other as shown by the solid line in Fig. 6C . Note that in the formed tubular body 3, the surface of the metal strip 2 on which the grooves are formed faces inward, so that grooves are provided on the inner wall.

[0059] Returning to Figure 4, above the fin pass rolls 38 and 39 in the vacuum chamber 21, a vacuum chamber 40 is provided that houses an electron beam welder 41 for welding the seam 5 of the tubular body 3 formed by the fin pass rolls 36-39.

[0060] A communication hole 42 is formed in the lower surface of the vacuum chamber 40, which is continuous with the through hole 25 in the upper surface of the vacuum chamber 21. An electron beam welder 41 is disposed inside the vacuum chamber 40 above the communication hole 42.

[0061] Although not shown, the electron beam welding machine 41 includes a cathode unit that generates an electron beam when a voltage is applied, an anode unit that accelerates the electron beam, and an electron lens unit that converges or deflects the electron beam. The electron beam welding machine 41 emits the electron beam generated by the cathode unit toward the above-mentioned communicating hole 42 and through-hole 25, and impinges on the joint 5 of the tubular body 3 in the vacuum chamber 21. In this way, the electron beam welding machine 41 welds the joint 5 of the tubular body 3 to produce the welded pipe portion 4.

[0062] At this time, the inside of the vacuum chamber 21 is in a vacuum state, so there is almost no oxygen present. As a result, in the welded pipe manufacturing apparatus 1, the weld formed at the seam 5 of the tubular body 3 where the electron beam is applied is less likely to oxidize. This results in a welded pipe that is strong.

[0063] The two ends of the above-mentioned metal strip 2, in other words the +Y end and the -Y end of the metal strip 2, are an example of the first end face and the second end face in the width direction of the metal strip 2 as defined in the present disclosure. Also, the portion formed or welded on the +X side of the metal strip 2 is an example of the first portion on one end side as defined in the present disclosure.

[0064] Furthermore, the above-mentioned vacuum chamber 21, the inlet 211, and the outlet 212 of the vacuum chamber 21 are an example of a first vacuum chamber, a first inlet, and a first outlet as defined in the present disclosure. Furthermore, the vacuum chamber 20, the inlet 201, and the outlet 202 of the vacuum chamber 20 are an example of a second vacuum chamber, a second inlet, and a second outlet as defined in the present disclosure. The vacuum chamber 22, the inlet 221, and the outlet 222 of the vacuum chamber 22 are an example of a third vacuum chamber, a third inlet, and a third outlet as defined in the present disclosure. Furthermore, the gaps 205, 206, and 215 are an example of a first gap as defined in the present disclosure. The gaps 216, 225, and 226 are an example of a second gap as defined in the present disclosure.

[0065] The above-described conveying rolls 23, 24 are an example of a feeding mechanism as defined in the present disclosure. The conveying rolls 23, 24 feeding the metal strip 2 are an example of a step of feeding the metal strip into the first vacuum chamber or a step of feeding the welded pipe out of the first vacuum chamber as defined in the present disclosure. The breakdown rolls 30-35 and the fin pass rolls 36-39 are an example of a forming roll as defined in the present disclosure.

[0066] Furthermore, the formation of grooves in the strip metal plate 2 by the above-mentioned stamping machines 13 and 14 is an example of a groove forming step as defined in the present disclosure. The first roll, second roll, third roll, and fourth roll provided in the stamping machines 13 and 14 are an example of groove forming rolls as defined in the present disclosure. Furthermore, the formation of the tubular body 3 by the above-mentioned breakdown rolls 30-35 and fin pass rolls 36-39 is an example of a tubular body forming step as defined in the present disclosure. Furthermore, the welding of the seam 5 of the tubular body 3 by the electron beam welder 41, i.e., the welding step, is an example of a welded pipe manufacturing step as defined in the present disclosure.

[0067] Furthermore, the various conditions of the electron beam welding machine 41 described above depend on the size and material of the welded pipe to be manufactured, but for example, it is recommended that the rated output be 6 kW, the acceleration voltage be 40 kV, the electron beam current be 5 to 150 mA, and the cathode be a W rod.

[0068] As described above, in the welded pipe manufacturing apparatus 1 according to the embodiment, the electron beam welder 41 performs welding by colliding an electron beam in a vacuum. Therefore, the manufacturing apparatus 1 can suppress oxidation of the welded portion formed. As a result, the strength of the welded portion is high, and the strength of the manufactured welded pipe is also high.

[0069] Furthermore, in the welded pipe manufacturing apparatus 1, there is no need to use an inert gas because the electron beam welder 41 performs welding in a vacuum. As a result, there is no need to prepare special gases, which simplifies the preparation and work for manufacturing welded pipes.

[0070] In the welded pipe manufacturing apparatus 1, a vacuum chamber 20 having a lower degree of vacuum than the vacuum chamber 21 where welding is performed is adjacent to the entrance 211 of the vacuum chamber 21. One end of the strip metal plate 2 to be processed passes through the vacuum chamber 20 and is then fed into the vacuum chamber 21 from the entrance 211. As a result, the degree of vacuum in the vacuum chamber 21 is less likely to decrease, making it easy to maintain a degree of vacuum sufficient for electron beam welding.

[0071] Similarly, in the welded pipe manufacturing apparatus 1, a vacuum chamber 22, which has a lower degree of vacuum than the vacuum chamber 21, is adjacent to the outlet 212 of the vacuum chamber 21. The welded pipe portion 4 after processing of the strip metal plate 2 is then sent out from the outlet 212 through the vacuum chamber 22. Therefore, the degree of vacuum in the vacuum chamber 21 is less likely to decrease, and it is easy to maintain a degree of vacuum sufficient for electron beam welding.

[0072] The above is a method for manufacturing a welded pipe according to an embodiment of the present disclosure. and Welded pipe manufacturing equipment 1 to The manufacturing method of welded pipes has been explained. and Welded pipe manufacturing equipment 1 is , but is not limited to this.

[0073] (Variation 1) In the first embodiment, only minute gaps 215 and 216 are provided at the entrance 211 and the exit 212 of the vacuum chamber 21. However, the vacuum chamber 21 is not limited to this. Seals may be provided at the entrance 211 and the exit 212 of the vacuum chamber 21.

[0074] FIG. 7 is a cross-sectional view of a modified example of the forming machine and welding machine included in the welded pipe manufacturing apparatus 1.

[0075] 7, a seal 50 may be provided along the inner wall surface at the entrance 211 of the vacuum chamber 21. Also, a seal 51 may be provided along the inner wall surface at the exit 212 of the vacuum chamber 21. This is because such a configuration increases the airtightness of the vacuum chamber 21, making it easier to maintain the degree of vacuum in the vacuum chamber 21. Furthermore, as a result, oxidation of the welded portion can be further suppressed.

[0076] In this case, although not shown, the seals 50, 51 may be frame-shaped or O-ring-shaped. The seals 50, 51 may be formed of a low-friction material, such as polytetrafluoroethylene, a fluororesin, to allow the band-shaped metal plate 2 or the welded pipe portion 4 to be inserted into and removed from the vacuum chamber 21. The seals 50, 51 may also be installed at the inlet 201 and outlet 202 of the vacuum chamber 20 and the inlet 221 and outlet 222 of the vacuum chamber 22 in the same arrangement as in the vacuum chamber 21. In this case, the seals 50, 51 should be installed preferentially in the vacuum chamber 21, which has a higher degree of vacuum, rather than in the vacuum chambers 20, 22.

[0077] (Variation 2) In the first embodiment, the end of the welded pipe portion 4 formed on one end of the metal strip 2 is sealed in advance to prevent air from entering the vacuum chambers 21 and 22, and the welded pipe manufacturing apparatus 1 is then operated in this state to manufacture the welded pipe. However, the means for preventing air from entering the vacuum chambers 21 and 22 is not limited to this. The welded pipe portion 4 of the metal strip 2 may also be plugged.

[0078] FIG. 8 is a cross-sectional view of another modified example of the forming machine and welding machine included in the welded pipe manufacturing apparatus 1.

[0079] 8, a plug 60 may be provided in the internal space of the -X end portion of the welded pipe portion 4. In particular, a small cylindrical plug 60 may be provided in the internal space of the portion immediately after the band metal sheet 2 has been formed into the tubular body 3 and welded by the electron beam welder 41. This is because such a configuration can prevent air from flowing in through the internal space of the welded pipe portion 4 of the band metal sheet 2.

[0080] In this case, one end of the plug 60 is fixed to the inner wall of the vacuum chamber 21, and the other end is bent and supported by a support rod 61 that is parallel to the X direction and inserted into the internal space of the welded pipe section 4 from the -X side. The plug 60 should have an outer diameter that allows it to be loosely inserted into the welded pipe section 4. The plug 60 should be made of a low-friction material, similar to the seals 50 and 51 of the first modification.

[0081] (Variation 3) In the embodiment, no measuring device is provided in vacuum chamber 20-22, but a measuring device may be provided in vacuum chamber 20-22, and welded pipe manufacturing apparatus 1 may operate based on the measurement results of the measuring device.

[0082] For example, the welded pipe manufacturing apparatus 1 may include a vacuum gauge installed in the vacuum chamber 21 to measure the vacuum level within the vacuum chamber 21. Here, the vacuum gauge may be, for example, a U-tube manometer or a diaphragm vacuum gauge. In the welded pipe manufacturing apparatus 1, if a weld defect exists in the welded pipe portion 4 of the tubular body 3 that was welded in the vacuum chamber 21, and the location of the weld defect passes through the vacuum chamber 22 and exits the vacuum chamber 22, air may flow into the welded pipe portion 4 from the location of the weld defect. In this case, the inflowing air may enter the vacuum chamber 21 through the unwelded seam 5 of the tubular body 3, reducing the vacuum level in the vacuum chamber 21 and further oxidizing the weld. Therefore, a vacuum gauge may be installed in the vacuum chamber 21, and a control device (described later) installed in the welded pipe manufacturing apparatus 1 may determine the presence or absence of the weld defect based on pressure data measured by the vacuum gauge. If the control device determines that a weld defect exists, the manufacturing apparatus 1 may stop producing welded pipe. Furthermore, if the control device determines that there is a weld defect, it may determine that the welded pipe portion 4 protruding outside the vacuum chamber 22 is defective, or it may determine that the portion after the welded pipe portion 4 inside the vacuum chamber 21 where the vacuum level has decreased is defective. When determining whether there is a weld defect, if the pressure measured by the vacuum gauge is a gauge pressure, it is preferable to convert the gauge pressure to absolute pressure. Then, it is preferable to determine that there is a weld defect if the pressure value measured by the vacuum gauge is greater than a threshold value.

[0083] Although the example in which the vacuum gauge is provided in the vacuum chamber 21 has been described, it is sufficient that the vacuum gauge is provided in at least one of the vacuum chambers 20-22.

[0084] (Variation 4) The vacuum gauges described above may be replaced by other vacuum measuring devices, for example, the vacuum gauges may be replaced by optical leak detectors.

[0085] FIG. 9 is a cross-sectional view of yet another modified example of the forming machine and welding machine included in the welded pipe manufacturing apparatus 1.

[0086] 9, the welded pipe manufacturing apparatus 1 may include an optical leak detector 70 that is installed in the vacuum chamber 22 and measures the degree of vacuum within the vacuum chamber 22. Here, the optical leak detector 70 is a device that is placed in a measurement environment, in this case, in a case that communicates with the vacuum chamber 22, and includes two electrodes that emit electrons when a potential difference is applied, and an optical measuring device that measures the spectral intensity of light emitted when the emitted electrons collide with atoms and molecules of the gas within the case, and calculates the partial pressure of the gas from the spectral intensity measured by the optical measuring device. Note that the two electrodes and the optical measuring device may be installed directly within the vacuum chamber 22, rather than within the case.

[0087] When outside air flows into the vacuum chamber 22, the optical measuring device included in the optical leak detector 70 measures the spectral intensity of purple light resulting from the nitrogen content of the outside air. Alternatively, since the outside air also contains oxygen, the optical measuring device measures the spectral intensity of dim purple light depending on the oxygen concentration. In light of this, when outside air flows into the vacuum chamber 22, the optical leak detector 70 may calculate the pressure inside the case from the measured spectral intensity, thereby determining the pressure inside the vacuum chamber 22. The control device 80 may then determine the presence or absence of the above-mentioned welding defects from the pressure determined by the optical leak detector 70.

[0088] It is preferable that the optical leak detector 70 be provided in the vacuum chamber 20 or 22, rather than in the vacuum chamber 21. If the optical leak detector 70 is provided in the vacuum chamber 21, the two electrodes of the optical leak detector 70 may act on the electron beam welding, causing welding to be performed in an inappropriate location.

[0089] The control device 80 may include a CPU (Central Processing Unit) 81 and a memory 82, and the CPU 81 may read and execute a judgment program stored in the memory 82 to perform the judgment process for determining whether or not there is a welding defect.

[0090] In the embodiment, the welded pipe manufacturing apparatus 1 includes three vacuum chambers 20-22. However, the welded pipe manufacturing apparatus 1 is not limited to this. In the welded pipe manufacturing apparatus 1, the vacuum chambers 20-22 may house a tubular body formed by bending the band-shaped metal sheet 2 in the width direction into a tubular shape, with a first end face in the width direction of the band-shaped metal sheet 2 facing a second end face opposite the first end face. Then, inside the vacuum chamber 20-22, the electron beam welder 41 produces a welded pipe by irradiating the first end face and the second end face of the tubular body with an electron beam to weld the first end face and the second end face together. Therefore, the number of vacuum chambers 20-22 may be arbitrary as long as these conditions are met. For example, the welded pipe manufacturing apparatus 1 may include only one vacuum chamber 21. This is because oxidation of the welded portion can be suppressed even in such a configuration.

[0091] In the embodiment, the vacuum chamber 20-22 accommodates the forming machine 15 and the welding machine 16. However, the equipment accommodated in the vacuum chamber 20-22 is not limited to this. As long as the electron beam welding machine 41 satisfies the above conditions and produces a welded pipe, other equipment for processing the strip metal plate 2 may be accommodated in the vacuum chamber 20-22.

[0092] FIG. 10 is a cross-sectional view of a modified example of the welded pipe manufacturing apparatus 1 according to the embodiment.

[0093] 10, the engraving machines 13, 14 and dancer rolls 131-133 described in the embodiment may be housed in a vacuum chamber 21. This allows grooves to be formed in the metal strip 2 in the vacuum chamber 21. In this configuration, a metal strip 2 having a flat surface without grooves enters through an entrance 211 of the vacuum chamber 21, thereby reducing the gap 215 at the entrance 211 and allowing the degree of vacuum in the vacuum chamber 21 to be lowered. This also makes it easier to maintain the degree of vacuum in the vacuum chamber 21.

[0094] In the embodiment, the welded pipe manufacturing apparatus 1 includes the accumulator 12. However, the welded pipe manufacturing apparatus 1 is not limited to this. In the welded pipe manufacturing apparatus 1, the accumulator 12 has an optional configuration. For example, if a decrease in production efficiency is acceptable, the welded pipe manufacturing apparatus 1 does not need to include the accumulator 12.

[0095] In the embodiment, the welded pipe manufacturing apparatus 1 is equipped with stamping machines 13 and 14. However, the welded pipe manufacturing apparatus 1 is not limited to this. In the welded pipe manufacturing apparatus 1, the stamping machines 13 and 14 may have any configuration. For example, when manufacturing a welded pipe without a groove, the welded pipe manufacturing apparatus 1 does not need to be equipped with the stamping machines 13 and 14. Furthermore, when manufacturing a welded pipe with a groove, it is sufficient for the welded pipe manufacturing apparatus 1 to be equipped with at least one stamping machine 13 or 14 to form the groove.

[0096] In the embodiment, the welded pipe manufacturing apparatus 1 does not include any machinery or devices after the recoiler 19. However, the welded pipe manufacturing apparatus 1 is not limited to this. The welded pipe manufacturing apparatus 1 may include an annealing device after the recoiler 19 to prevent the manufactured welded pipe from cracking during bending or expanding.

[0097] In the embodiments, the welded pipe manufacturing apparatus 1 is described using an example in which the welded pipe to be manufactured is a heat transfer tube used in a heat exchanger. However, the welded pipe to be manufactured is not limited to this. The welded pipe manufacturing method and welded pipe manufacturing apparatus 1 according to the embodiments of the present disclosure are applicable to all welded pipes that require suppression of oxidation of the weld.

[0098] As described above, the welded pipe manufacturing method and the welded pipe manufacturing apparatus 1 are not limited to the above-described embodiment, and various modifications and substitutions can be made. Various embodiments of the present disclosure are described below as appendices.

[0099] (Appendix 1) a step of producing a welded pipe by applying an electron beam to the first end face and the second end face of a tubular body formed by bending a band-shaped metal plate in a width direction into a tubular shape, the tubular body having a first end face in the width direction of the band-shaped metal plate and a second end face opposite the first end face, facing each other, thereby welding the first end face and the second end face to each other, Manufacturing method of welded pipe. (Appendix 2) The method further includes a step of bending the band-shaped metal plate into a tubular shape in the width direction in a vacuum space, thereby forming the tubular body having a shape in which the first end surface and the second end surface face each other, In the step of producing the welded pipe, the electron beam is made to collide with the first end surface and the second end surface of the tubular body in the vacuum space, thereby welding the first end surface and the second end surface to each other. 10. A method for manufacturing a welded pipe as described in Appendix 1. (Appendix 3) The method further includes a step of feeding the belt-shaped metal plate into a first vacuum chamber having the vacuum space from one end side in the belt extension direction, In the step of forming the tubular body, a first portion of the belt-shaped metal plate at the one end side is bent in the width direction into a tubular shape inside the first vacuum chamber, thereby forming the tubular body in the first portion; In the step of producing the welded pipe, the electron beam is made to collide with the first end surface and the second end surface of the tubular body formed into the first portion inside the first vacuum chamber, thereby welding the first end surface and the second end surface to each other. 2. A method for manufacturing a welded pipe as described in Appendix 2. (Appendix 4) further comprising a step of forming grooves on the surface of the belt-shaped metal plate in a vacuum space, In the step of producing the welded pipe, the first end surface and the second end surface of the tubular body are formed by bending the band-shaped metal plate with the plate surface having the grooves facing inward, and the electron beam is made to collide with the first end surface and the second end surface in the vacuum space, thereby welding the first end surface and the second end surface to each other. 4. A method for manufacturing a welded pipe according to any one of claims 1 to 3. (Appendix 5) The method further includes a step of feeding the belt-shaped metal plate into a first vacuum chamber having the vacuum space from one end side in the belt extension direction, In the step of forming the groove, the groove is formed in a plate surface of a first portion of the belt-shaped metal plate located on the one end side inside the first vacuum chamber, In the step of producing the welded pipe, the first portion of the belt-shaped metal plate is curved with the plate surface on which the grooves are formed facing inward, and the first end surface and the second end surface of the tubular body formed in the first portion are then bombarded with the electron beam inside the first vacuum chamber to weld the first end surface and the second end surface to each other. 5. A method for manufacturing a welded pipe as described in Appendix 4. (Appendix 6) The welded pipe fabricated into the first portion is then fed out of the first vacuum chamber, a second vacuum chamber adjacent to the first vacuum chamber and having a lower vacuum level than the first vacuum chamber is provided on the side of the first vacuum chamber into which the one end of the belt-shaped metal plate is fed; a third vacuum chamber adjacent to the first vacuum chamber and having a lower vacuum level than the first vacuum chamber is provided on the side of the first vacuum chamber from which the welded pipe is fed out, In the step of feeding the belt-shaped metal plate into the first vacuum chamber, the belt-shaped metal plate is fed into the first vacuum chamber via the second vacuum chamber; In the step of feeding the welded pipe from the first vacuum chamber, the welded pipe is fed from the first vacuum chamber to the outside via the third vacuum chamber. 6. A method for producing a welded pipe according to claim 3 or 5. (Appendix 7) In the step of preparing the welded pipe, one end of the welded pipe is sealed, and an internal space of the welded pipe is in the same vacuum as the interior of the first vacuum chamber. 7. A method for manufacturing a welded pipe according to any one of appendixes 3, 5, and 6. (Appendix 8) the step of producing the welded pipe includes a step of measuring, with a vacuum gauge, a degree of vacuum in a space in which the electron beam is made to impinge on the first end surface and the second end surface, and determining whether or not a welding defect exists based on the measured value of the degree of vacuum. 8. A method for manufacturing a welded pipe according to any one of appendices 1 to 7. (Appendix 9) The step of producing the welded pipe includes a step of causing electrons to collide with gas in another space that communicates with a space in which the electron beam is collided with the first end surface and the second end surface, causing light to be emitted, measuring the spectrum of the emitted light to determine the pressure of the gas, thereby determining the degree of vacuum in the space in which the electron beam is collided, and determining the presence or absence of a welding defect based on the determined degree of vacuum. 8. A method for manufacturing a welded pipe according to any one of appendices 1 to 7. (Appendix 10) a first vacuum chamber that accommodates a tubular body formed by bending a band-shaped metal plate in a tubular shape in a width direction, the tubular body having a first end face in the width direction of the band-shaped metal plate and a second end face opposite the first end face, the first end face facing each other; an electron beam welder that produces a welded pipe by applying an electron beam to the first end surface and the second end surface of the tubular body inside the first vacuum chamber to weld the first end surface and the second end surface together; A welded pipe manufacturing apparatus comprising: (Appendix 11) a feeding mechanism that feeds the belt-shaped metal plate into the first vacuum chamber from one end side in the belt extension direction, The first vacuum chamber is a first inlet through which the strip metal plate is fed from the one end side; a first outlet through which the welded pipe fabricated at the portion on the one end side is fed out, the first outlet being formed by welding the second end surface to the first end surface of the tubular body by the electron beam welding machine as the band-shaped metal plate is fed from the one end side to the first inlet by the feeding mechanism; and and The first vacuum chamber accommodates, in its internal space, a forming roll that bends a portion of the one end side of the belt-shaped metal plate fed into the first vacuum chamber from the first inlet by the feeding mechanism into a tubular shape in the width direction, and forms a tubular body in the portion of the one end side with the first end face and the second end face facing each other. 11. The apparatus for manufacturing a welded pipe according to claim 10. (Appendix 12) a groove forming roll that forms grooves on a surface of the belt-shaped metal plate that has been fed into the first vacuum chamber from the first inlet by the feeding mechanism is accommodated in an internal space of the first vacuum chamber; The forming roll forms the tubular body by curving the first portion of the band-shaped metal plate with the plate surface on which the grooves are formed facing inward. 12. The apparatus for manufacturing a welded pipe according to claim 11. (Appendix 13) a second vacuum chamber adjacent to the first vacuum chamber on the side of the first vacuum chamber where the first inlet is located, the second vacuum chamber having a lower vacuum level than the first vacuum chamber; a third vacuum chamber adjacent to the first vacuum chamber on the side of the first vacuum chamber where the first outlet is located, the third vacuum chamber having a lower vacuum level than the first vacuum chamber; Furthermore, the second vacuum chamber has a second inlet through which the strip metal plate is fed from the one end side by the feeding mechanism, and a second outlet through which the strip metal plate is fed from the one end side by the feeding mechanism into the second inlet, and the second outlet is connected to the first inlet, thereby communicating with the first vacuum chamber; the third vacuum chamber has a third inlet into which the welded pipe fabricated on the portion of the strip metal plate at the one end side is fed from the first outlet by the feeding mechanism, and a third outlet through which the welded pipe fabricated on the portion of the strip metal plate at the one end side is fed into the third inlet by the feeding mechanism, and the third inlet is connected to the first outlet, thereby communicating with the first vacuum chamber. 13. The apparatus for manufacturing a welded pipe according to claim 11 or 12. (Appendix 14) the first inlet, the second inlet, and the second outlet have a first gap between the flat band-shaped metal plate and the first inlet, the second inlet, and the second outlet, allowing the band-shaped metal plate to slide therethrough when the band-shaped metal plate is inserted therethrough; the first outlet, the third inlet, and the third outlet have a second gap between the welded pipe, which is formed in a portion of the belt-shaped metal plate at the one end side, and the welded pipe, in a state where the welded pipe is inserted therethrough, allowing the welded pipe to slide therethrough. 14. The apparatus for manufacturing a welded pipe according to claim 13. (Appendix 15) One end of the welded pipe located outside the first vacuum chamber is sealed, and the internal space of the welded pipe is in the same vacuum as the interior of the first vacuum chamber. 15. An apparatus for manufacturing a welded pipe according to any one of claims 10 to 14. (Appendix 16) a vacuum gauge for measuring the degree of vacuum in the internal space of the first vacuum chamber; a control device that determines whether or not there is a welding defect in the welded pipe produced by the electron beam welding machine based on the measurement value of the vacuum gauge; Further provided with 16. An apparatus for manufacturing a welded pipe according to any one of claims 10 to 15. (Appendix 17) an optical leak detector that measures a spectrum of light emitted when electrons collide with a gas in a space communicating with the first vacuum chamber to determine the pressure of the gas, thereby determining the degree of vacuum in the internal space of the first vacuum chamber; a control device that determines whether or not there is a welding defect in the welded pipe manufactured by the electron beam welding machine based on the degree of vacuum in the internal space determined by the optical leak detector; Further provided with 16. An apparatus for manufacturing a welded pipe according to any one of claims 10 to 15.

[0100] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to explain the present disclosure and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and within the meaning of the disclosure equivalent thereto are considered to be within the scope of the present disclosure.

[0101] This application is based on Japanese Patent Application No. 2022-95328 filed on June 13, 2022. The entire specification, claims, and drawings of Japanese Patent Application No. 2022-95328 are incorporated herein by reference. [Explanation of symbols]

[0102] 1 welded pipe manufacturing equipment, 2 strip metal plate, 3 tubular body, 4 welded pipe section, 5 joint, 10 uncoiler, 11 splicing machine, 12 accumulator, 13, 14 stamping machine, 15 forming machine, 16 welding machine, 17 drawing machine, 18 cutting machine, 19 recoiler, 20-22 vacuum chamber, 23, 24 conveying roll, 25 through hole, 30-35 breakdown roll, 36-39 fin pass roll, 40 vacuum chamber, 41 electron beam welding machine, 42 connecting hole, 50, 51 seal, 60 plug, 61 support rod, 70 optical leak detector, 80 control device, 81 CPU, 82 memory, 111 holder, 131-133 dancer roll, 181 cutter, 191 winding section, 201 inlet, 202 Outlets, 205,206 gaps, 211 inlets, 212 outlets, 215,216 gaps, 221 inlets, 222 outlets, 225,226 gaps, 301 convex parts, 311 recesses, 321 convex parts, 331 recesses, 341 convex parts, 351 recesses, 361,381 fin parts.

Claims

1. a step of producing a welded pipe by applying an electron beam to the first end face and the second end face of a tubular body formed by bending a band-shaped metal plate in a width direction into a tubular shape, the tubular body having a first end face in the width direction of the band-shaped metal plate and a second end face opposite the first end face, facing each other, thereby welding the first end face and the second end face together; The step of producing the welded pipe includes a step of causing electrons to collide with gas in another space that communicates with a space in which the electron beam is collided with the first end surface and the second end surface, causing light to be emitted, measuring the spectrum of the emitted light to determine the pressure of the gas, thereby determining the degree of vacuum in the space in which the electron beam is collided, and determining the presence or absence of a welding defect based on the determined degree of vacuum. Manufacturing method of welded pipe.

2. The method further includes a step of bending a first portion of the belt-shaped metal plate, located at one end side in the belt extending direction, into a tubular shape in the width direction inside a vacuum chamber having a vacuum space, to form the first portion into the tubular body having a shape in which a first end face in the width direction of the belt-shaped metal plate and a second end face opposite the first end face face each other, In the step of producing the welded pipe, an electron beam is applied to the first end surface and the second end surface of the tubular body formed in the first portion inside the vacuum chamber to weld the first end surface and the second end surface to each other, and a plug supported by a support rod inserted from the opposite side to the one end of the belt-shaped metal plate is disposed inside the tubular body formed in the first portion, and the first end surface and the second end surface are welded to each other. The method for manufacturing a welded pipe according to claim 1 .

3. forming grooves on the surface of the belt-shaped metal plate inside the vacuum chamber; In the step of producing the welded pipe, the first end surface and the second end surface of the tubular body formed by bending the band-shaped metal plate with the plate surface having the grooves facing inward are bombarded with the electron beam inside the vacuum chamber, thereby welding the first end surface and the second end surface to each other. The method for manufacturing a welded pipe according to claim 2.

4. In the step of forming the groove, the groove is formed on the plate surface of the portion located on the one end side of the belt-shaped metal plate inside the vacuum chamber, In the step of producing the welded pipe, the first portion of the belt-shaped metal plate is curved with the plate surface on which the grooves are formed facing inward, and the first end surface and the second end surface of the tubular body formed in the first portion are then bombarded with the electron beam inside the vacuum chamber to weld the first end surface and the second end surface to each other. The method for manufacturing a welded pipe according to claim 3.

5. the method further includes a step of feeding the band-shaped metal plate into the vacuum chamber from the one end side, and a step of feeding the welded pipe fabricated into the first portion out of the vacuum chamber, The vacuum chamber includes: a first vacuum chamber into which the one end of the strip metal plate is fed and where the step of forming the first portion into the tubular body and the step of producing the welded pipe are performed; a second vacuum chamber, which is adjacent to the first vacuum chamber and has a lower vacuum level than the first vacuum chamber, and which is disposed on a side of the first vacuum chamber where the one end of the belt-shaped metal plate is fed, a third vacuum chamber, which is disposed on the side of the first vacuum chamber from which the welded pipe is fed out, adjacent to the first vacuum chamber, and has a lower vacuum level than the first vacuum chamber; is provided, In the step of feeding the belt-shaped metal plate into the vacuum chamber, the belt-shaped metal plate is fed into the first vacuum chamber via the second vacuum chamber; In the step of feeding the welded pipe out of the vacuum chamber, the welded pipe is fed out of the first vacuum chamber via the third vacuum chamber. The method for manufacturing a welded pipe according to claim 2.

6. the step of producing the welded pipe includes a step of measuring, with a vacuum gauge, a degree of vacuum in a space in which the electron beam is made to impinge on the first end surface and the second end surface, and determining whether or not a welding defect exists based on the measured value of the degree of vacuum. The method for manufacturing a welded pipe according to claim 1 or 2.

7. a first vacuum chamber that accommodates a tubular body formed by bending a band-shaped metal plate in a tubular shape in a width direction, the tubular body having a first end face in the width direction of the band-shaped metal plate and a second end face opposite the first end face, the first end face facing each other; an electron beam welder that produces a welded pipe by applying an electron beam to the first end surface and the second end surface of the tubular body inside the first vacuum chamber to weld the first end surface and the second end surface together; an optical leak detector that measures a spectrum of light emitted when electrons collide with a gas in a space communicating with the first vacuum chamber to determine the pressure of the gas, thereby determining the degree of vacuum in the internal space of the first vacuum chamber; a control device that determines whether or not there is a welding defect in the welded pipe manufactured by the electron beam welding machine based on the degree of vacuum in the internal space determined by the optical leak detector; Equipped with Welded pipe manufacturing equipment.

8. The first vacuum chamber accommodates a tubular body of a band-shaped metal plate, the first portion of which is formed into a tubular body with a first end face in the width direction and a second end face opposite the first end face by bending a first portion located at one end side in the direction in which the band extends into a tubular shape in the width direction, the electron beam welding machine applies an electron beam to the first end surface and the second end surface of the tubular body in the first portion inside the first vacuum chamber to weld the first end surface and the second end surface together, thereby producing a welded pipe; a support rod is provided on an inner wall of the first vacuum chamber, the support rod being inserted into the tubular body in the first portion from the side opposite to the one end side of the belt-shaped metal plate and supporting a plug that closes the internal space of the tubular body; The apparatus for manufacturing a welded pipe according to claim 7.

9. a feeding mechanism for feeding the belt-shaped metal plate from the one end side into the first vacuum chamber, The first vacuum chamber is a first inlet through which the strip metal plate is fed from the one end side; a first outlet through which the welded pipe fabricated in a first portion on the one end side is fed out, the first portion being formed by welding the second end surface to the first end surface of the tubular body by the electron beam welding machine as the band-shaped metal plate is fed from the one end side to the first inlet by the feeding mechanism; and and The first vacuum chamber accommodates, in its internal space, a forming roll that bends the first portion of the belt-shaped metal plate fed into the first vacuum chamber from the first inlet by the feeding mechanism into a tubular shape in the width direction, and forms the tubular body in the first portion with the first end face and the second end face facing each other. The apparatus for manufacturing a welded pipe according to claim 8.

10. a groove forming roll that forms grooves on a surface of the belt-shaped metal plate that has been fed into the first vacuum chamber from the first inlet by the feeding mechanism is accommodated in an internal space of the first vacuum chamber; The forming roll forms the tubular body by curving the first portion of the band-shaped metal plate with the plate surface on which the grooves are formed facing inward. The apparatus for manufacturing a welded pipe according to claim 9.

11. the first vacuum chamber accommodates the electron beam welder and the forming roll, and has the first inlet and the first outlet; The welded pipe manufacturing apparatus comprises: a second vacuum chamber adjacent to the first vacuum chamber on the side of the first vacuum chamber where the first inlet is located, the second vacuum chamber having a lower vacuum level than the first vacuum chamber; a third vacuum chamber adjacent to the first vacuum chamber on the side of the first vacuum chamber where the first outlet is located, the third vacuum chamber having a lower vacuum level than the first vacuum chamber; Furthermore, the second vacuum chamber has a second inlet through which the strip metal plate is fed from the one end side by the feeding mechanism, and a second outlet through which the strip metal plate is fed from the one end side by the feeding mechanism into the second inlet, and the second outlet is connected to the first inlet, thereby communicating with the first vacuum chamber; the third vacuum chamber has a third inlet into which the welded pipe fabricated on the first portion of the strip metal plate is fed from the first outlet by the feeding mechanism, and a third outlet through which the welded pipe fabricated on the first portion of the strip metal plate is fed into the third inlet by the feeding mechanism, and through which the welded pipe is fed out, and the third inlet is connected to the first outlet, thereby communicating with the first vacuum chamber. The apparatus for manufacturing a welded pipe according to claim 9.

12. the first inlet, the second inlet, and the second outlet have a first gap between the flat band-shaped metal plate and the first inlet, the second inlet, and the second outlet, allowing the band-shaped metal plate to slide therethrough when the band-shaped metal plate is inserted therethrough; the first outlet, the third inlet, and the third outlet have a second gap between the first outlet, the third inlet, and the third outlet, allowing the welded pipe to slide when the welded pipe is inserted through the first inlet, the third inlet, and the third outlet. The apparatus for manufacturing a welded pipe according to claim 11.

13. a vacuum gauge for measuring the degree of vacuum in the internal space of the first vacuum chamber; a control device that determines whether or not there is a welding defect in the welded pipe produced by the electron beam welding machine based on the measurement value of the vacuum gauge; Further provided with The apparatus for manufacturing a welded pipe according to claim 8.

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