CN116568417A

CN116568417A - Welded pipe and method for manufacturing welded pipe

Info

Publication number: CN116568417A
Application number: CN202280007128.3A
Authority: CN
Inventors: 斋藤拓也
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2021-01-14
Filing date: 2022-01-12
Publication date: 2023-08-08
Also published as: WO2022154004A1; JPWO2022154004A1; JP7391246B2

Abstract

The welded pipe (1A) is formed by aligning a first end portion (10A) of a plate-like body (2A) bent into a tubular shape in the bending direction and a second end portion (20A) located on the opposite side of the first end portion (10A), and welding the first end portion (10A) and the second end portion (20A). The first end portion (10A) has: a first end face; a first surface part formed by a part of an outer wall surface (102) of the plate-like body (2A) on the first end surface side; and a first step formed by recessing the first surface portion toward the inside of the pipe, the second end portion (20A) having: a second end face; a second surface part formed by a part of the inner wall surface (101) of the plate-like body (2A) on the second end surface side and aligned with the first surface part of the first end part (10A); and a welding part by which the second end surface is welded to the first face part of the first end part (10A).

Description

Welded pipe and method for manufacturing welded pipe

Technical Field

The present disclosure relates to welded pipes and methods of manufacturing welded pipes.

Background

Welded pipes are manufactured by bending a metal plate into a tubular shape, aligning both ends thereof to form a joint, and welding the joint. In the welded pipe, there is a welded pipe in which a recess is provided in a joint so as to suppress a weld formed during welding from protruding toward the inside of the pipe.

For example, patent document 1 discloses a welded pipe having a concave portion gradually deepening toward a joint. In the welded pipe described in patent document 1, a weld formed when welding a joint is formed in a recess. Therefore, the weld is less likely to protrude to the inside of the tube than the inner wall of the tube adjacent to the concave portion. Conventionally, a pipe expanding tool is sometimes inserted into a welded pipe to perform machining. In the welded pipe described in patent document 1, by providing the above-described structure, the pipe expanding tool is prevented from cutting the weld joint and generating cutting scraps.

Prior art literature

Patent literature

Patent document 1: japanese unexamined patent publication No. 3-106206

Disclosure of Invention

Problems to be solved by the invention

However, in the welded pipe described in patent document 1, end surfaces of metal plates are aligned with each other, and end surface portions having smaller end surfaces are welded. Therefore, there is a concern that sufficient welding strength cannot be obtained.

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a welded pipe having high welding strength while suppressing the projection of a weld bead to the inside of the pipe, and a method for manufacturing the welded pipe.

Means for solving the problems

In order to achieve the above object, a welded pipe of the present disclosure is a welded pipe in which a first end portion of a plate-like body bent into a tubular shape in a bending direction and a second end portion located on an opposite side of the first end portion are aligned and welded. In the welded pipe, the first end portion has: a first end face; a first surface portion formed by a portion of an outer wall surface of the plate-like body, the portion being located on the first end surface side; and a first step formed by recessing the first surface portion toward the inside of the pipe. The second end portion has: a second end face; a second surface portion formed by a portion of the inner wall surface of the plate-like body on the second end surface side, and aligned with the first surface portion of the first end portion; and a welding portion by which the second end face is welded to the first face portion provided in the first end portion.

Effects of the invention

According to the structure of the present disclosure, the second end portion has: a second surface portion formed by a portion of the inner wall surface of the plate-like body on the second end surface side, and aligned with the first surface portion of the first end portion; and a welding portion by which the second end face is welded to the first face portion provided in the first end portion. Therefore, the projection of the weld formed at the welded portion into the pipe can be suppressed. In addition, the welded pipe has high welding strength.

Drawings

Fig. 1 is a perspective view of a welded pipe according to embodiment 1 of the present disclosure.

Fig. 2 is an expanded view of a welded pipe according to embodiment 1 of the present disclosure.

Fig. 3 is an enlarged view of region III shown in fig. 1.

Fig. 4 is a cross-sectional view at the IV-IV line of severance shown in fig. 2.

Fig. 5 is a flowchart of a method for manufacturing a welded pipe according to embodiment 1 of the present disclosure.

Fig. 6 is a conceptual diagram of a calender roll used in a step of forming a plate-like body included in the method for manufacturing a welded pipe according to embodiment 1 of the present disclosure.

Fig. 7 is an enlarged perspective view of a modified example of the welded pipe according to embodiment 1 of the present disclosure.

Fig. 8 is a perspective view of a welded pipe according to embodiment 2 of the present disclosure.

Fig. 9 is an expanded view of a welded pipe according to embodiment 2 of the present disclosure.

Fig. 10 is an enlarged view of the region X shown in fig. 8.

FIG. 11 is a cross-sectional view taken along line XI-XI shown in FIG. 9.

Fig. 12 is an enlarged perspective view of a modified example of the welded pipe according to embodiment 2 of the present disclosure.

Detailed Description

Hereinafter, a welded pipe and a method of manufacturing the welded pipe according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or equivalent portions are denoted by the same reference numerals.

(embodiment 1)

The welded pipe according to embodiment 1 is a welded pipe with an inner surface groove used in a heat exchanger. The welded pipe is manufactured by bending a metal plate into a tubular shape, and aligning and welding both end portions of the metal plate. In such a production, steps are provided at both end portions of the metal plate of the welded pipe in order to facilitate alignment of both end portions.

First, the structure of the welded pipe will be described with reference to fig. 1 and 2. Next, the structure of the steps at both end portions will be described with reference to fig. 3 and 4.

Fig. 1 is a perspective view of a welded pipe 1A according to embodiment 1. Fig. 2 is an expanded view of the welded pipe 1A. In fig. 1, only the pipe end portion of the welded pipe 1A extending in the axial direction AD is shown for easy understanding. In addition, the welded portion 30A is omitted. Fig. 2 shows the welded pipe 1A after being unfolded, as seen from the inner wall surface 101 side.

As shown in fig. 1, the welded pipe 1A includes a plate-like body 2A bent into a circular tube shape.

As shown in fig. 2, the plate-like body 2A is formed of a strip material. In the present specification, the strip means an elongated metal sheet or a strip-like metal sheet having a rectangular cross section. In fig. 2, although only a part of the strip is shown, the strip extends in the direction of arrow A1. The length of the strip is longer than the width W of the strip.

In order to improve the heat transfer property, the plate-like body 2A is made of copper, more specifically, phosphorus deoxidized copper or oxygen free copper having a high purity and a small oxide content. As shown in fig. 1 and 2, the plate-like body 2A is formed with a plurality of grooves 3 to enhance heat transfer from the refrigerant when the refrigerant flows therethrough. Thereby, protruding fins 4 are formed between the grooves 3 and the grooves 3. In order to stir the refrigerant by the fins 4, the grooves 3 are inclined with respect to the width direction WD as shown in fig. 2.

The plate-like body 2A is formed with the surface on which the groove 3 is formed facing inward, and is curved in the width direction WD with the surface on which the groove 3 is formed as the inner wall surface 101. Further, both end portions in the width direction WD overlap. Thereby, the plate-like body 2A forms the welded tube 1A shown in fig. 1. In order to easily align both end portions when forming the welded pipe 1A, steps 13A, 23A are formed at both end portions of the plate-like body 2A. Next, steps at both end portions of the plate-like body 2A will be described with reference to fig. 3 and 4.

Fig. 3 is an enlarged view of region III shown in fig. 1. Fig. 4 is a cross-sectional view at the IV-IV line of severance shown in fig. 2. In fig. 3, unlike fig. 1, a welded portion 30A is illustrated. Fig. 4 shows the welded pipe 1A with the inner wall surface 101 being in a state of being in an upper state and an outer wall surface 102 being in a lower state.

As shown in fig. 3, the plate-like body 2A has a first end portion 10A and a second end portion 20A, and the first end portion 10A and the second end portion 20A overlap each other by bending the plate surface into a circular tube shape. The first end portion 10A and the second end portion 20A are ends located in the bending direction BD of the plate-like body 2A.

In the first end portion 10A, as shown in fig. 4, an outer wall surface 102 on the end surface 11A side is recessed toward the inner wall surface 101 side. That is, the outer wall surface 102 is recessed toward the inside of the tube. As shown in fig. 3, this is provided so that the second end portion 20A is easily fitted into the recess of the first end portion 10A and overlapped when the welded pipe 1A is formed by overlapping the inner wall surface 101 of the second end portion 20A with the outer wall surface 102 side of the first end portion 10A. The inner wall surface 101 is a surface provided with the bottom of the groove 3.

As shown in fig. 4, the first end portion 10A has a step 13A between the surface 5 of the outer wall surface 102 located at the center in the width direction WD and the surface 12A located on the end surface 11A side and the outer wall surface 102 side by recessing the outer wall surface 102 on the end surface 11A side toward the pipe inside. The surface 12A is flat when developed as shown in fig. 4 so as to overlap the second end portion 20A without having a structure that forms irregularities.

In contrast, the second end portion 20A overlaps the first end portion 10A from the outside of the pipe, and thus the inner wall surface 101 on the end surface 21A side is recessed. Specifically, the inner wall surface 101 on the end surface 21A side is recessed to the outside of the pipe opposite to the portion having the step 13A of the first end portion 10A described above. Thus, the second end portion 20A has a step 23A between the surface 6 of the inner wall surface 101 located at the center in the width direction WD and the surface 22A located on the end surface 21A side of the inner wall surface 101.

In order to enable the second end portion 20A to be fitted with the first end portion 10A, the width W2 of the second end portion 20A, i.e., the distance from the step 23A to the end face 21A, is the same as the width W1 of the first end portion 10A, i.e., the distance from the step 13A to the end face 11A.

Further, in order to bring the second end portion 20A into a state in which the second end portion 20A does not protrude outside the pipe from a portion of the first end portion 10A that is closer to the end face 11A than the step 13A when the second end portion 20A is aligned with the first end portion 10A, the thickness T2 of the second end portion 20A is the same as the height H1 of the step 13A of the first end portion 10A. The surface 22A located at the second end portion 20A is flat when expanded as shown in fig. 4 so as to overlap the first end portion 10A without having a structure that forms irregularities.

In addition, in order to bring the first end portion 10A into a state in which the first end portion 10A does not protrude toward the inside of the pipe from a portion of the second end portion 20A that is closer to the end surface 21A than the step 23A when the second end portion 20A is fitted to the first end portion 10A, the height H2 of the step 23A of the second end portion 20A is the same as the thickness T1 of the first end portion 10A.

As shown in fig. 3, the second end portion 20A coincides with the face 12A of the first end portion 10A with a space 7 therebetween from the step 13A of the first end portion 10A. The width W7 of the space 7 is 1/2 of the width W1 of the first end portion 10A or 1/2 of the width W2 of the second end portion 20A described above. The overlapping width W3 of the first end portion 10A and the second end portion 20A is 1/2 of the width W1 of the first end portion 10A or 1/2 of the width W2 of the second end portion 20A.

The dimensions of such first end portion 10A and second end portion 20A are determined for the following reasons. For this reason, in detail, when the welded pipe 1A is formed to have a desired pipe outer diameter or pipe inner diameter, there is a case where the relative position of the second end portion 20A with respect to the first end portion 10A is shifted due to an error in the width W dimension of the plate-like body 2A shown in fig. 4, which occurs at the time of manufacturing. As a result, sometimes the second end portion 20A is not aligned with the first end portion 10A. Regarding the first end portion 10A and the second end portion 20A, the first end portion 10A is reliably aligned with the second end portion 20A by setting the width W1 of the first end portion 10A to a value larger than the maximum value of the error of the generated width W dimension, and disposing the end face 21A of the second end portion 20A in the center of the width direction WD of the face 12A located at the first end portion 10A, thereby forming the dimensions as described above. Alternatively, regarding the first end portion 10A and the second end portion 20A, the width W2 of the second end portion 20A is set to a value larger than the maximum value of the error of the generated width W dimension, and the end face 11A of the first end portion 10A is disposed in the center of the width direction WD of the face 22A located at the second end portion 20A, whereby the first end portion 10A and the second end portion 20A are reliably aligned, and thus formed to the above-described dimension.

In addition, when the width W1 of the first end portion 10A and the width W2 of the second end portion 20A are formed to have the same size as a tolerance of the dimension of the width W shown in fig. 4 of the plate-like body 2A, for example, a tolerance of the dimension of the width direction WD of the strip forming the plate-like body 2A, the overlapping width W3 of the first end portion 10A and the second end portion 20A shown in fig. 3 is 1/2 of the value of the tolerance. Thereby, even if an error occurs in the dimension of the width W of the plate-like body 2A, the second end portion 20A can be reliably aligned with the first end portion 10A. As a result, it is possible to prevent a gap from being generated between the second end portion 20A and the first end portion 10A, and thus the pipe from being unable to function.

In addition, regarding the above tolerance, since a standard of an allowable difference of the width of the strip with respect to the thickness is specified in japanese industrial standards, it is preferable to use the allowable difference of the standard as the tolerance. For example, in japanese industrial standard JIS H3100 "plates and strips of copper and copper alloy", an allowable difference in width with respect to thickness is specified, and therefore, it is preferable to use the allowable difference of the standard as a tolerance on the premise of using a strip conforming to the standard.

On the other hand, as shown in fig. 3, a weld 30A is arranged in the space 7 between the end face 21A of the second end portion 20A and the step 13A of the first end portion 10A.

The weld 30A is formed by filling molten material between the end face 21A of the second end portion 20A and the step 13A of the first end portion 10A. That is, the welded portion 30A is formed by the molten material remaining in the space 7 between the end face 21A of the second end portion 20A and the step 13A of the first end portion 10A at the time of welding. Thereby, the weld 30A welds the end face 21A of the second end portion 20A and the face 12A of the first end portion 10A. Further, the end face 21A of the second end portion 20A and the step 13A are welded. In this welding, the formed weld 30A is supported by the face 12A of the first end portion 10A, and therefore the weld 30A does not enter and protrude to the inside of the pipe. In addition, when a recess is provided in the outer peripheral surface of the welded pipe 1A, stress is easily concentrated in the recess. Therefore, in order to enhance the strength of the welded pipe 1A, the welded portion 30A preferably fills the portion of the space 7 and welds the first end portion 10A and the second end portion 20A.

In this way, in the welded pipe 1A, the first end portion 10A and the second end portion 20A are easily fitted. Further, the welded portion 30A fills the portion of the space 7, whereby the welded portion 30A joins the first end portion 10A and the second end portion 20A with high strength. Next, a method of manufacturing the welded pipe 1A will be described with reference to fig. 5 and 6.

Fig. 5 is a flowchart of a method of manufacturing the welded pipe 1A. Fig. 6 is a conceptual diagram of the calender rolls 200 and 300 used in the step of forming the plate-like body 2A included in the method of manufacturing the welded pipe 1A.

First, although not shown in fig. 5, a bar having the width W and having no structure such as grooves or protrusions formed on the surface is prepared, and the bar is made of phosphorus-deoxidized copper or oxygen-free copper. For example, a strip wound into a roll is prepared. Since the rolling is performed by the rolling rolls 200 and 300 described later, a strip thicker than the thickness of the pipe wall of the welded pipe 1A to be manufactured may be prepared in consideration of the rolling rate during the rolling.

Next, as shown in fig. 5, grooves 3 and steps 13A, 23A are formed on the prepared strip, thereby forming a plate-like body 2A (step S1). For example, a strip drawn from a roll is passed between a reduction roll 200 shown in fig. 6 and a reduction roll 300 pressed by the reduction roll 200. Here, the calender roll 200 has a concave-convex portion 210 and a convex portion 220 for forming the groove 3 and the second end portion 20A. Further, the calender roll 300 has a convex portion 310 for forming the first end portion 10A. When a web passes between these calender rolls 200 and 300, the irregularities of the irregularities 210, the protrusions 220, 310 are transferred to the web. Thereby, a first end portion 10A, a second end portion 20A having steps 13A, 23A are formed in the strip. As a result, the plate-like body 2A in the expanded state shown in fig. 2 is formed.

In addition, in the case of preparing the plate-like body 2A in which the groove 3 and the steps 13A, 23A are formed in advance, the step S1 may be omitted.

Returning to fig. 5, next, the plate-like body 2A is formed into a circular tube shape (step S2). For example, a so-called welding device is used to bend the plate-like body 2A in the width direction WD shown in fig. 2 in a state where the surface on which the groove 3 and the second end portion 20A are formed is inside. As a result, the plate-like body 2A is formed in a state in which the second end portion 20A is aligned with the first end portion 10A shown in fig. 1 and 3. In this molding, since the end face 21A of the second end portion 20A is disposed in the center of the first end portion 10A in the width direction WD shown in fig. 4, the second end portion 20A is not easily detached from the first end portion 10A, and the second end portion 20A is easily aligned with the first end portion 10A.

Next, the first end portion 10A and the second end portion 20A aligned by molding are welded (step S3). In detail, when the second end portion 20A is aligned with the first end portion 10A in step S2, a space 7 shown in fig. 3 is formed between the step 13A of the first end portion 10A and the end face 21A of the second end portion 20A described above. Therefore, the welding portion 30A is formed at the portion having the space 7 by using a welder provided in the electric welding apparatus. In this welding, the molten material remains in the entire interior space of the space 7. Thereby, the welded portion 30A does not enter the inside of the pipe. Further, the welded portion 30A does not protrude into the tube. Further, by filling the internal space of the space 7 with the welded portion 30A, the welding strength is improved.

Although the specific method of welding in step S3 is not particularly limited, in order to maintain the shape of the groove 3, high-frequency induction welding, laser welding, TIG (Tungsten Insert Gas: tungsten inert gas) welding are preferable to resistance welding in terms of the welding method.

Next, although not shown, a portion of the welded portion 30A protruding from the outer wall surface 102 is cut away. At this time, since the welded portion 30A is formed in the inner space of the space 7, even if the portion of the welded portion 30A protruding from the outer wall surface 102 is cut away, the welding strength of the welded portion 30A can be maintained. Next, the plate-like body 2A molded into a circular tube shape in step S2 and welded in step S3 is reduced to a target diameter using a so-called drawing device. Further, the tubular plate-like body 2A having a reduced diameter is cut to a target length, and then the shape is corrected. Through the above operation, the welded pipe 1A is completed.

In addition, in the case of manufacturing the welded tube 1A having an outer diameter of 7.00mm, a height of the fins 4 from the inner wall surface 101 of 0.230mm, and a thickness of the plate-like body 2A at the bottom of the groove 3 of 0.290mm, the width W1 of the first end portion 10A and the width W2 of the second end portion 20A described above may be 0.8mm. This is because, in the case of using a strip made of phosphorus-deoxidized copper or oxygen-free copper having a thickness of 0.570mm and a width W of 2.20mm on the premise that the strip is rolled by an amount of 0.05mm during the rolling by the rolling rolls 200, 300 in the above step S1, the tolerance of the width W of the strip is set to ±0.4mm in accordance with the japanese industrial standard JIS H3100 "standards for plates and strips of copper and copper alloy".

As described above, in the welded pipe 1A of embodiment 1, the second end portion 20A has: an inner wall surface 101 aligned with the surface 12A of the first end portion 10A; and a welded portion 30A, the end face 21A of the second end portion 20A being welded to the face 12A of the first end portion 10A by the welded portion 30A, so that the welded portion 30A does not protrude into the pipe. Further, since the welded portion 30A is formed in a state where the inner wall surface 101 of the second end portion 20A is aligned with the surface 12A of the first end portion 10A, the welding strength of the welded portion 30A is also high.

Further, in the welded pipe 1A, the welded portion 30A fills between the end face 21A of the second end portion 20A and the step 13A of the first end portion 10A. Therefore, the welding strength of the welded portion 30A is further improved.

Further, since the welded portion 30A is formed between the step 13A of the first end portion 10A and the end face 21A of the second end portion 20A, the welded portion 30A is less likely to protrude from the outer wall surface 102. Further, even if the welded portion 30A protrudes from the outer wall surface 102 and the protruding portion is shaved off, the welding strength of the welded portion 30A can be maintained. As a result, the welded pipe 1A is less likely to be broken.

The width W1 of the first end portion 10A and the width W2 of the second end portion 20A have the same size as the tolerance of the dimension of the width W of the plate-like body 2A, and the end face 21A of the second end portion 20A is arranged at the center in the width direction WD of the first end portion 10A. Therefore, the second end portion 20A can be prevented from being separated from the first end portion 10A, and a gap or a through hole can be prevented from being generated between the second end portion 20A and the first end portion 10A.

The height H1 of the step 13A of the first end portion 10A coincides with the thickness T2 of the second end portion 20A. Further, the thickness T1 of the first end portion 10A coincides with the height H2 of the step 23A of the second end portion 20A. Thus, the overall thickness of the portion where the first end portion 10A is aligned with the second end portion 20A is the same as the thickness of the other portions of the welded pipe 1A. As a result, the welded pipe 1A is less likely to deform against bending moment. That is, if the entire thickness of the portion where the first end portion 10A and the second end portion 20A are aligned is different from the thickness of the other portion of the welded pipe 1A, the portion where the thickness is small is easily deformed. However, the welded pipe 1A is not deformed because such a portion is not present.

In addition, the welded tube 1A may be used for a heat exchanger. For example, the welded tube 1A may be assembled with fins and flow a refrigerant therein. In the interior of the welded tube 1A, the first end portion 10A does not protrude into the tube interior, and therefore, tube expansion processing at the time of assembling the fins is easy.

The end face 11A, the face 12A, and the step 13A of the first end portion 10A are examples of the first end face, the first face, and the first step of the first end portion described in the present specification. The end face 21A, the face 22A, and the step 23A of the second end portion 20A are examples of the second end face, the second face, and the second step of the second end portion described in the present specification. The axial direction AD is an example of the tube axis direction. The first end portion 10A and the second end portion 20A may be exchanged, and the first end portion 10A and the second end portion 20A may be referred to as an example of the second end portion and the first end portion described in the present specification.

The step S1 is an example of the step of forming the first step described in the present specification. Step S2 is an example of the process of aligning the other surface of the second end portion with the first surface portion described in the present specification. Step S3 is an example of the process of welding the second end portion to the first end portion described in the present specification.

(modification)

In embodiment 1, the material forming the welded portion 30A is filled in the entire inner space of the space 7 between the step 13A of the first end portion 10A and the end face 21A of the second end portion 20A. In other words, the welded portion 30A fills the entire internal space of the space 7. However, the welded portion 30A is not limited thereto. The welded portion 30A may be provided in part or all of the inner space of the space 7.

Fig. 7 is an enlarged perspective view of a modification of the welded pipe 1A of embodiment 1. In fig. 7, the same region as the III region shown in fig. 1 is enlarged in a modified example of the welded pipe 1A.

As shown in fig. 7, in the welded pipe 1A, the welded portion 30A may be provided in a part of the inner space of the space 7. In detail, the welded portion 30A may extend linearly along the end surface 21A of the second end portion 20A. Thereby, the weld 30A can join the end face 21A of the second end portion 20A with the face 12A of the first end portion 10A. Although not shown, the welded portion 30A may be formed intermittently along the end surface 21A of the second end portion 20A. This is because, even in this manner, the inner wall surface 101 of the second end portion 20A on the end surface 21A side of the step 23A is in close contact with the surface 12A of the first end portion 10A, and thus functions sufficiently as a pipe.

As a result, the welded portion 30A is provided only in a part of the inner space of the space 7, and as a result, only a part of the inner space of the space 7 may be filled. In this manner, the inner wall surface 101 of the second end portion 20A is also aligned with the surface 12A of the first end portion 10A, and therefore, in the welded pipe 1A, a state in which the welding strength of the welded portion 30A is high can be maintained.

(embodiment 2)

In the welded pipe 1A of embodiment 1, steps 13A, 23A are formed in both the first end portion 10A and the second end portion 20A. And, the end face 11A of the first end portion 10A and the end face 21A of the second end portion 20A are recessed. However, the welded pipe 1A is not limited thereto. The welded pipe 1A may be recessed only in either one of the first end portion 10A and the second end portion 20A.

The welded pipe 1B of embodiment 2 is a welded pipe having a step 13B at the first end portion 10B and no step at the second end portion 20B.

The welded pipe 1B according to embodiment 2 will be described below with reference to fig. 8 to 11. In embodiment 2, a description will be given mainly of a configuration different from that of embodiment 1.

Fig. 8 is a perspective view of welded pipe 1B according to embodiment 2. Fig. 9 is an expanded view of the welded pipe 1B. Fig. 10 is an enlarged view of the region X shown in fig. 8. FIG. 11 is a cross-sectional view taken along line XI-XI shown in FIG. 9.

In fig. 8, only the pipe end portion of the welded pipe 1B is shown, as in fig. 1. In addition, the welded portion 30B is omitted. Fig. 9 shows the welded pipe 1B when the plate-like body 2B provided in the welded pipe 1B is unfolded and viewed from the inner wall surface 101 side, as in fig. 2.

As shown in fig. 8 and 10, the first end portion 10B is bent into a crank shape in a tube cross-sectional view, that is, in a tube cross-sectional view. Specifically, the outer wall surface 102 is bent once in the tube center axis direction, and then is bent in the tube circumferential direction. As shown in fig. 11, in this tube cross-sectional view, the bent length of the crank-shaped bend in the tube center axis direction is smaller than the length from the inner wall surface 101 to the opening surface of the groove 3, in other words, the distance D from the inner wall surface 101 to the top of the fin 4. Thus, a crank-like bend is formed on the tube outside of the top of the fin 4 in a tube cross-sectional view. As a result, the first end portion 10B is prevented from protruding toward the inside of the tube. Thus, for example, when the diameter of the welded pipe 1B is enlarged by inserting the pipe expanding tool, the pipe expanding tool can be prevented from being blocked.

Further, the first end portion 10B has a step 13B by being bent into a crank shape in a tube cross-sectional view. The step 13B has a surface 12B having no undulation on the end surface 11B side. In contrast, no step is formed at the second end portion 20B. In the case where the second end portion 20B has no step, it may happen that the second end portion 20B protrudes to the outside of the tube when the second end portion 20B coincides with the first end portion 10B from the outside of the tube of the first end portion 10B. However, the first end portion 10B has a step 13B. As a result, such extension of the second end portion 20B can be prevented. Further, in order to prevent the protrusion of the second end portion 20B when the first end portion 10B is overlapped with the second end portion 20B, the first end portion 10B is bent in a crank shape toward the inside of the tube by the thickness T2 of the second end portion 20B in a tube cross-sectional view. As a result, the height H1 of the step 13B is the same as the thickness T2 of the second end portion 20B. Further, the same as the thickness T1 of the first end portion 10B.

Further, the thickness T1 of the first end portion 10B is smaller than the distance D from the inner wall surface 101 to the top of the fin 4. Thereby, the thickness T1 is set as follows: when the second end portion 20B is overlapped with the first end portion 10B from the outside of the tube, the first end portion 10B does not protrude into the tube than the fins 4 located on the second end portion 20B side.

On the other hand, as shown in fig. 9, the second end portion 20B is not formed with the fins 4, and as a result, the surface 22B of the second end portion 20B is free from undulation, and is flat in the unfolded state shown in fig. 9. Thereby, the second end portion 20B can be contacted without a gap when overlapped with the first end portion 10B. In addition, as shown in fig. 11, the surface 22B of the second end portion 20B is the same height as the bottom of the groove 3 in the pipe inside direction.

As shown in fig. 10, the second end portion 20B is aligned with the first end portion 10B from outside the tube. The end surface 21B of the second end portion 20B is disposed away from the step 13B of the first end portion 10B by the distance 7. The width W7 of the space 7 is 1/2 of the width W1 shown in fig. 11 of the first end portion 10B or the width W2 of the second end portion 20B. As shown in fig. 10, a welded portion 30B is formed at the space 7. These intervals 7 and the welded portions 30B are the same as the intervals 7 and the welded portions 30A described in embodiment 1. Therefore, a detailed description of these is omitted.

As described above, in the welded pipe 1B of embodiment 2, the first end portion 10B is bent into a crank shape in a pipe sectional view, and the second end portion 20B is aligned with the face 12B of the first end portion 10B. The welded pipe 1B is easier to manufacture because no step is formed in the second end portion 20B as compared with the welded pipe 1A of embodiment 1.

Further, the first end portion 10B is formed on the tube outer side than the top of the fin 4, and therefore is less likely to be an obstacle in tube expansion. Further, when the fluid flows in the welded pipe 1B, the first end portion 10B is not liable to disturb the flow of the fluid.

Since the welded portion 30B is buried between the step 13B of the first end portion 10B and the end surface 21B of the second end portion 20B, the welded portion 30B does not protrude into the pipe as in embodiment 1. In addition, the welding strength of the welded portion 30B is also high. Further, the welded portion 30B is less likely to protrude from the outer wall surface 102. As described in the modification of embodiment 1, the welded portion 30B is not limited to filling the entire internal space of the space 7, and may fill only a part of the internal space of the space 7. That is, the welded portion 30B may be provided only in a part of the inner space of the space 7.

As described above, the welded pipes 1A and 1B and the manufacturing methods of the welded pipes 1A and 1B according to the embodiments of the present disclosure are described, but the welded pipes 1A and 1B and the manufacturing methods of the welded pipes 1A and 1B are not limited thereto.

For example, in embodiment 2, the first end portion 10B is bent into a crank shape in a tube cross-sectional view, and the second end portion 20B is linear in the tube cross-sectional view. However, the welded pipes 1A, 1B are not limited thereto.

Fig. 12 is an enlarged perspective view of a modification of the welded pipe 1B of embodiment 2. In fig. 12, the same region as in fig. 10 is displayed in an enlarged manner.

As shown in fig. 12, in the case where the first end portion 10B is bent in a crank shape in a tube cross-sectional view to have the step 13B, the second end portion 20B may also have the step 23B by recessing the inner wall surface 101 of the end surface 21B toward the wall outside. In short, the second end portion 20A described in embodiment 1 may be combined with the first end portion 10B described in embodiment 2 and having a crank shape in a tube cross-sectional view. In this way, the welded portion 30B does not protrude into the tube. In this manner, the weld 30B is provided in the entire inner space of the space 7, so that the weld strength can be improved. In this modified example of the welded pipe 1B, the space 7 may be filled only with a part of the space 7, not only with the whole space.

In embodiments 1 and 2, the welded pipes 1A and 1B are round pipes, but the welded pipes 1A and 1B are not limited thereto. The welded pipes 1A and 1B may be tubular. That is, the plate-like bodies 2A, 2B may be bent into a tubular shape. For example, the welded pipes 1A and 1B may be flat pipes.

In embodiments 1 and 2, the welded pipes 1A and 1B are formed of copper, but the welded pipes 1A and 1B are not limited thereto. The material of the welded pipes 1A and 1B is arbitrary. For example, the material of the welded pipes 1A and 1B may be aluminum or an aluminum alloy as long as it is metal. The material of the welded pipes 1A and 1B may be resin. Even with such a material, it is possible to align the first end portions 10A, 10B with the second end portions 20A, 20B and weld the first end portions 10A, 10B and the second end portions 20A, 20B. In the case where the material of the welded pipes 1A and 1B is resin, the strip described in embodiment 1 is an elongated resin sheet or a band-shaped resin sheet having a rectangular cross section.

In embodiments 1 and 2, the end surfaces 11A and 11B of the first end portions 10A and 10B are planar. The end surfaces 21A, 21B of the second end portions 20A, 20B are planar. However, the first end portions 10A, 10B and the second end portions 20A, 20B are not limited thereto. For example, chamfer portions may be formed on the end surfaces 11A, 11B of the first end portions 10A, 10B. Similarly, chamfer portions may be formed on the end surfaces 21A, 21B of the second end portions 20A, 20B. For example, the chamfer may be a so-called C chamfer or R chamfer. Even in such a shape, the above-described calender rolls 200 and 300 can be used for manufacturing.

In embodiments 1 and 2, a plurality of grooves 3 are formed in the inner wall surfaces 101 of the plate-like bodies 2A and 2B. However, the groove 3 is not limited thereto. The grooves 3 may be provided in at least 1 on the inner wall surface 101 of the plate-like bodies 2A, 2B.

As shown in fig. 2 and 9, the groove 3 preferably intersects with the direction of arrow A1 in which the end surfaces 21A, 21B of the second end portions 20A, 20B extend. It is particularly preferable that the direction of arrow A1 extends with respect to the end surfaces 21A and 21B. This is because, even when the fluid flows through the welded pipes 1A and 1B and the pressure of the fluid is applied to the groove 3, the welded portions 30A and 30B are less likely to be peeled off as long as the welded portions 30A and 30B extend along the end surfaces 21A and 21B and the groove 3 intersects the direction in which the welded portions 30A and 30B extend.

The present disclosure may be carried out in various embodiments and variations without departing from the broad spirit and scope of the disclosure. The above-described embodiments are for illustrating the present disclosure, and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is not indicated by the embodiments, but by the scope of the claims. And, various modifications implemented within the meaning of the claims and the equivalents thereof are considered to be within the scope of the present disclosure.

The present application is based on Japanese patent application No. 2021-3957 filed on 1 month 14 of 2021. The specification, claims, drawings of Japanese patent application publication No. 2021-3957 are incorporated into the present specification by reference in their entirety.

Description of the reference numerals

1A, 1B: welding the pipe; 2A, 2B: a plate-like body; 3: a groove; 4: a fin; 5. 6: a noodle; 7: spacing; 10A, 10B: a first end portion; 11A, 11B: an end face; 12A, 12B: a noodle; 13A, 13B: a step; 20A, 20B: a second end portion; 21A, 21B: an end face; 22A, 22B: a noodle; 23A, 23B: a step; 30A, 30B: a welding part; 101: an inner wall surface; 102: an outer wall surface; 200: a calender roll; 210: a concave-convex portion; 220: a convex portion; 300: a calender roll; 310: a convex portion; a1: arrows; AD: axial direction; BD: a bending direction; d: a distance; h1, H2: height of the steel plate; t1 and T2: thickness; WD: a width direction; w, W1, W2, W3, W7: width of the material.

Claims

1. A welded pipe is formed by aligning a first end portion of a plate-like body bent into a tubular shape in a bending direction and a second end portion on the opposite side of the first end portion, and welding the first end portion and the second end portion,

the first end portion has: a first end face; a first surface portion formed by a portion of an outer wall surface of the plate-like body, the portion being located on the first end surface side; and a first step formed by recessing the first face portion toward the inside of the tube,

the second end portion has: a second end face; a second surface portion formed by a portion of an inner wall surface of the plate-like body on the second end surface side and aligned with the first surface portion of the first end portion; and a welding portion by which the second end face is welded to the first face portion provided in the first end portion.

2. The welded pipe according to claim 1, wherein,

the welding part is buried between the second end face and the first step.

3. The welded pipe according to claim 1 or 2, wherein,

the second end portion has a second step recessed from the second face portion toward the outside of the tube.

4. A welded pipe according to any one of claims 1 to 3, wherein,

the second end face is located between the first end face and the first step.

5. The welded pipe according to claim 3, wherein,

the thickness of the first end portion is the same as the height of the second step.

6. The welded pipe according to any one of claims 1 to 5, wherein,

the thickness of the first end portion is the same as the height of the first step.

7. The welded pipe according to claim 6, wherein,

the first end portion has the first step by bending the plate-like body into a crank shape toward the inside of the tube.

8. The welded pipe according to claim 7, wherein,

the welded pipe includes a plurality of grooves provided between the first end portion and the second end portion and extending in a direction inclined with respect to a pipe axis direction,

the surface of the first end portion on the inner side of the tube, which is bent into a crank-like shape, is located on the outer side of the tube than the opening surfaces of the plurality of groove openings.

9. The welded pipe according to any one of claims 1 to 8, wherein,

the welded pipe has a groove provided in a portion of the inner wall surface other than the second surface, and agitates the fluid when the fluid flows inside the pipe.

10. The welded pipe according to claim 9, wherein,

the groove extends in a direction intersecting the second end face,

the weld extends along the second end face and intersects the groove.

11. A method for manufacturing a welded pipe, comprising the steps of:

bending a strip-shaped plate-like body in a strip direction with one plate surface as an inner side, wherein the strip-shaped plate-like body is provided with a first step formed by recessing the one plate surface toward the other plate surface side at a first end portion positioned in the strip direction, and the other surface of a second end portion positioned on the opposite side of the first end portion is aligned with a first surface portion positioned on the one plate surface side of the first end portion and positioned on the first end surface side of the first step; and

after the other face of the second end portion is aligned with the first face portion, a weld is formed to weld a second end face of the second end portion to the first face portion of the first end portion.

12. The method for manufacturing a welded pipe according to claim 11, wherein,

in the step of welding the second end surface to the first surface portion provided in the first end portion, the welding portion is formed between the second end surface and the first step, and the welding portion fills the space between the second end surface and the first step.

13. The method for manufacturing a welded pipe according to claim 11 or 12, wherein,

the method also comprises the following steps: before aligning the other face of the second end portion with the first face portion, the first step is formed at the first end portion in the belt direction of the belt-like plate-like body,

in the step of forming the first step, a second step is formed in which the second end portion is recessed toward the second end face side so that the other plate faces the one plate face side,

in the step of aligning the other surface of the second end portion with the first surface portion, a second surface portion is aligned with the first surface portion, wherein the second surface portion is located on the other plate surface side of the second end portion and on the second end surface side of the second step.