Segment bent pipe

Abstract

To provide a segment bent pipe in which short pipes are accurately joined at a predetermined angle by butt-fusion.SOLUTION: A segment bent pipe 10 is formed by joining end surfaces of short pipes, each of which is formed by writing a marked line extending in a pipe axis direction on an outer peripheral surface of a raw pipe having a straight pipe form and cutting the raw pipe so that a cross section forms a predetermined angle relative to the marked line, by butt fusion in a state that positions of the marked lines of the adjacent short pipes are matched. Each marked line 18 is formed excluding bead parts 16 formed during butt fusion on the outer peripheral surface of the segment bent pipe so as to extend in the pipe axis direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a segmented curved pipe, and more particularly to a segmented curved pipe formed by connecting a plurality of short pipes by butt fusion, for example.

Background Art

[0002] An example of a conventional segmented curved pipe is disclosed in Non-Patent Document 1. It is common to produce a segmented curved pipe by cutting a straight original pipe obliquely to produce a plurality of short pipes and connecting the end faces of these short pipes by butt fusion.

Prior Art Documents

Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During the manufacture of pipes, the manufacturer, size, production lot, etc. are printed, so such pipe markings are also attached to the original pipe of the segmented curved pipe. Therefore, it is convenient to use this pipe marking as a reference when cutting the original pipe or butt-fusing the short pipes together. However, such pipe markings are set to a large size so as to be easily readable (that is, wide), and there are also portions on the original pipe where there are no pipe markings. For this reason, if the pipe marking is used as a reference, the processing accuracy deteriorates, and there is a risk that the short pipes cannot be accurately butt-fused at a predetermined angle.

[0005] Therefore, the main object of the present invention is to provide a novel segmented curved pipe.

[0006] Another object of the present invention is to provide a segmented curved pipe in which short pipes are accurately butt-fused at a predetermined angle.

[0007] Still another object of the present invention is to provide a segmented curved pipe that can easily perform position adjustment during pipe installation work. **Means for Solving the Problems**

[0008] A first invention is a segmented curved pipe formed by connecting a plurality of short pipes by butt fusion, wherein a reference line extending in the pipe axis direction is marked on the outer peripheral surface of a straight original pipe, and the original pipe is cut so that the cutting surface forms a predetermined angle with respect to the reference line, and the end surfaces of the short pipes thus produced are butt-fused with the positions of the reference lines of adjacent short pipes aligned. The reference line is formed so as to extend in the pipe axis direction on the outer peripheral surface of the segmented curved pipe except for the bead portion formed during butt fusion.

[0009] According to the first invention, since it has a reference line marked during manufacturing, it is possible to easily and accurately perform position adjustment between short pipes during butt fusion, and provide a segmented curved pipe in which short pipes are accurately butt-fused at a predetermined angle. Also, since the reference line marked during manufacturing remains even when the product is completed, it is possible to provide a segmented curved pipe that can easily and accurately perform position adjustment during pipe installation work.

[0010] A second invention is subordinate to the first invention, and the reference lines are formed at four locations on the top, bottom, inside, and outside when the bending direction of the segmented curved pipe is the horizontal direction.

[0011] According to the second invention, position adjustment during manufacturing and pipe installation work can be performed more easily and accurately.

[0012] A third invention is subordinate to the first or second invention, and the width of the reference line is set to be 3% or less of the outer diameter of the segmented curved pipe when the outer diameter of the segmented curved pipe is 355 mm or less, and 2% or less of the outer diameter of the segmented curved pipe when the outer diameter of the segmented curved pipe exceeds 355 mm.

[0013] According to the third invention, the accuracy of position adjustment during manufacturing and piping can be more effectively improved.

[0014] The fourth invention is dependent on the first or second invention, and the reference lines are formed continuously or intermittently so as to extend over the entire length of the segment curved pipe.

[0015] According to the fourth invention, position adjustment during piping work can be carried out more easily and accurately.

[0016] The fifth invention is dependent on the first or second invention, and the color difference between the outer peripheral surface of the segment curved pipe and the reference lines is 10 or more.

[0017] According to the fifth invention, since the operator can easily identify the reference lines, the accuracy of position adjustment during manufacturing and piping can be more effectively improved.

[0018] The sixth invention is a method for manufacturing a segment curved pipe formed by connecting a plurality of short pipes by butt fusion, comprising: (a) a step of marking a reference line extending in the pipe axis direction on the outer peripheral surface of a straight original pipe; (b) a step of cutting the original pipe after step (a) to produce short pipes so that the cutting surface forms a predetermined angle with respect to the reference line; and (c) a step of butt-fusing the end faces of the adjacent short pipes with the positions of the reference lines of the short pipes aligned after step (b).

[0019] According to the sixth invention, since the reference line is marked on the outer peripheral surface of the original pipe, the position adjustment between the short pipes during butt fusion can be carried out easily and accurately, and a segment curved pipe in which the short pipes are accurately butt-fused at a predetermined angle can be manufactured. In addition, since the reference line marked during manufacturing remains even when the product is completed, a segment curved pipe that can facilitate and accurately perform position adjustment during piping work can be provided.

[0020] The seventh invention is a construction method of a segmented curved pipe formed by connecting a plurality of short pipes by butt fusion, comprising: (a) marking a reference line extending in the pipe axis direction on the outer peripheral surface of a straight original pipe, cutting the original pipe so that the cutting surface forms a predetermined angle with respect to the reference line, and butt-fusing the end faces of the short pipes thus produced with the positions of the reference lines of adjacent short pipes aligned, thereby preparing two segmented curved pipes in which the reference lines, excluding the bead portions formed during butt fusion, are formed to extend in the pipe axis direction on the outer peripheral surface of the segmented curved pipe; and (b) butt-fusing the end faces of the two segmented curved pipes with the positions of the reference lines aligned so that the two segmented curved pipes are connected in a predetermined orientation.

[0021] According to the seventh invention, a 90-degree bent pipe or an offset pipe can be easily and accurately constructed.

Advantages of the Invention

[0022] According to this invention, it is possible to provide a segmented curved pipe in which short pipes are accurately butt-fused at a predetermined angle and the position adjustment during pipe work can be easily performed.

[0023] The above object, other objects, features, and advantages of this invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0025] Referring to FIG. 1, a segment bent pipe 10 (also referred to as a segment bend) according to an embodiment of the present invention is formed of a polyolefin synthetic resin such as polyethylene and polybutene. In this embodiment, the segment bent pipe 10 is made of polyethylene. As will be described in detail later, the segment bent pipe 10 is formed by connecting a plurality of short pipes 24 and 26 formed by cutting a raw pipe 20 by butt fusion (see FIGS. 4 and 5).

[0026] The use and nominal diameter of the segment bent pipe 10 are not particularly limited, but the segment bent pipe 10 is preferably used for various pipes such as those in factories and plants, and pressure pipes with a relatively large nominal diameter such as those in small hydropower equipment piping. The outer diameter of the segment bent pipe 10 is, for example, 250 mm - 800 mm.

[0027] As shown in FIGS. 1 - 3, the segment bent pipe 10 includes a bent pipe portion 12 provided at the central portion in the pipe axis direction and straight pipe portions 14 provided at both ends in the pipe axis direction. In this embodiment, the bent pipe portion 12 is bent at 90 degrees, and the two straight pipe portions 14 extend (open) in directions orthogonal to each other. That is, the segment bent pipe 10 of this embodiment is a 90 - degree bend. The bent pipe portion 12 is mainly composed of a plurality of first short pipes 24, and the straight pipe portions 14 are composed of second short pipes 26. In addition, an annular bead portion 16 extending in the circumferential direction is formed at the connection portion between the first short pipes 24 and at the connection portion between the first short pipe 24 and the second short pipe 26.

[0028] In addition, on the outer peripheral surface of the segment bent pipe 10, excluding the bead portion 16, marking lines 18 are formed so as to extend along the pipe axis direction. In FIG. 3, the marking lines 18 are shown as dotted marks for easy understanding of their positions, but actually, the marking lines 18 are lines marked with an oil-based pen (marking pen) or the like. In this embodiment, four marking lines 18 are formed at 90-degree intervals so as to be arranged in the circumferential direction. When the bending direction of the segment bent pipe 10 is the horizontal direction (that is, when the segment bent pipe 10 is arranged such that both straight pipe portions 14 extend in the horizontal direction), the marking lines 18 are formed at four locations, namely, the top, bottom, inside, and outside. Further, each of the four marking lines 18 is continuously formed over the entire length of the segment bent pipe 10, excluding the bead portion 16, that is, formed as a solid line up to the pipe ends of the segment bent pipe 10. At this time, the marking lines 18 are formed up to the position in contact with the base portion (rising portion) of the bead portion 16.

[0029] The width (thickness) of the marking line 18 is preferably as small (thin) as possible within a range that can be easily identified by the operator. This is to improve the accuracy of position adjustment during manufacturing and piping, which will be described later. Specifically, when the outer diameter of the segment bent pipe 10 is 355 mm or less, the width of the marking line 18 is preferably set to 3% or less of the outer diameter of the segment bent pipe 10. When the outer diameter of the segment bent pipe 10 exceeds 355 mm, the width of the marking line 18 is preferably set to 2% or less of the outer diameter of the segment bent pipe 10.

[0030] In addition, the color difference between the outer peripheral surface of the segment bent pipe 10 and the marking line 18 is preferably 10 or more. This is because the operator can easily identify the marking line 18. Here, the color difference referred to here is the color difference (ΔE) in the L*a*b* color system defined in JIS Z8781-4:2013. Specifically, when the outer peripheral surface of the segment bent pipe 10 is black, the marking line 18 is preferably white. When the outer peripheral surface of the segment bent pipe 10 is blue, the marking line 18 is preferably black or white.

[0031] Hereinafter, with reference to FIGS. 4 and 5, an example of the manufacturing method of the segment bent pipe 10 of this embodiment will be described. When manufacturing the segment bent pipe 10, first, as shown in FIG. 4, short pipes 24 and 26 are produced. Here, first, as shown in FIG. 4(a), a raw pipe 20 (a polyethylene pipe) made of straight tubular polyethylene with a predetermined length is prepared. Then, using an oil-based pen or the like, a reference line 22 extending in the axial direction of the raw pipe 20 is marked on the outer peripheral surface of the raw pipe 20 over the entire length of the raw pipe 20 (at least the entire length of the portion used for manufacturing the segment bent pipe 10). In this embodiment, four reference lines 22 arranged at 90-degree intervals in the circumferential direction are marked on the outer peripheral surface of the raw pipe 20.

[0032] Next, the raw pipe 20 is set in a cutting machine (not shown) so that one of the reference lines 22 is directly above or directly beside. Then, as shown by the virtual line X in FIG. 4(b), the raw pipe 20 is cut so that the cutting surface makes a predetermined angle with respect to the reference line 22, thereby producing a plurality of short pipes 24 and 26 as shown in FIG. 4(c). In this embodiment, the raw pipe 20 is cut so that the cutting surface makes an angle of 82.5 degrees (that is, 7.5 degrees with respect to the radial direction of the raw pipe 20) with respect to the reference line 22, thereby producing five first short pipes 24 and two second short pipes 26. In this way, by cutting the raw pipe 20 using the reference line 22 as a guide, short pipes 24 and 26 with end faces inclined at a predetermined angle with respect to the reference line 22 can be accurately produced.

[0033] Subsequently, as shown in FIG. 5, the segment bent pipe 10 is formed by connecting the end faces of the plurality of short pipes 24 and 26 by butt fusion. Here, first, as shown in FIG. 5(a), the end face of the first short pipe 24 and the end face of the second short pipe 26 are butted against each other, and the positions of their respective reference lines 22 are aligned. At this time (before butt fusion), the ends of the reference lines 22 of the adjacent short pipes 24 and 26 are in contact with each other. In this way, by using the reference line 22 as a guide, the position adjustment of the short pipes 24 and 26 during butt fusion can be easily and accurately performed.

[0034] Then, in this state (the state where the alignment marks of the adjacent short pipes 24 and 26 are aligned), the first short pipe 24 and the second short pipe 26 are butt-fused using a butt fusion machine (not shown). Then, as shown in FIG. 5(b), a bead portion 16 is formed at the connection portion (butt fusion portion) between the first short pipe 24 and the second short pipe 26. At this time, the alignment mark 22 that was present at the butt fusion portion becomes the bead portion 16, and what was the alignment mark 22 within the bead portion 16 melts and merges. As a result, the alignment mark 22 remains up to the position in contact with the root portion of the bead portion 16 and disappears in the bead portion 16.

[0035] After that, in the same manner, with the alignment marks 22 of each other aligned, the first short pipe 24 is sequentially connected to the first short pipe 24 by butt fusion, and finally the second short pipe 26 is connected, thereby manufacturing the segment bent pipe 10 as shown in FIG. 5(c). The alignment mark 22 entered during manufacturing remains as an alignment mark 18 extending in the pipe axis direction on the outer peripheral surface of the segment bent pipe 10 when the product is completed. That is, the segment bent pipe 10 has an alignment mark 18 formed continuously in the pipe axis direction over its entire length except for the bead portion 16 formed during butt fusion.

[0036] Such a segment bent pipe 10 has alignment marks 18 at four locations, above and below, inside and outside, on the outer peripheral surface, so that the position adjustment (centering) during piping work at the construction site can be easily performed. For example, when bending the pipe horizontally, it is advisable to place the alignment mark 18 that comes to the top when the bending direction of the segment bent pipe 10 is horizontal directly above. Also, when standing the pipe vertically (or lowering it), it is advisable to place the alignment mark 18 that comes to the inside (or outside) of the bending direction directly above when the bending direction of the segment bent pipe 10 is horizontal.

[0037] Also, when installing the segment bent pipe 10, prepare two segment bent pipes 10, and butt-weld the end faces of the two segment bent pipes 10 with the positions of the marking lines 18 aligned so that the two segment bent pipes 10 are connected in a predetermined orientation, whereby the offset pipe can be easily and accurately installed. That is, by aligning and butt-welding the marking line 18 at the top of one segment bent pipe 10 and the marking line 18 at the bottom of the other segment bent pipe 10, the S-shaped pipe can be easily and accurately installed.

[0038] As described above, according to this embodiment, since it has the marking line 22 filled in during manufacturing, the position adjustment between the short pipes 24 and 26 during butt-welding can be easily and accurately performed, and a segment bent pipe 10 in which the short pipes 24 and 26 are accurately butt-welded at a predetermined angle can be provided. Further, since the marking line 22 filled in during manufacturing remains as the marking line 18 even when the product is completed, the position adjustment during the piping work can be easily performed.

[0039] In the above-described embodiment, a 90-degree bend in which both end portions (straight pipe portions) extend in directions orthogonal to each other is exemplified, but the segment bent pipe may be a 22.5-degree bend, a 45-degree bend, or the like as shown in FIG. 6.

[0040] For example, when the segment bent pipe is a 45-degree bend, prepare two segment bent pipes, and butt-weld the end faces of the two segment bent pipes with the positions of the marking lines aligned so that the two segment bent pipes are connected in a predetermined orientation, whereby a 90-degree bent pipe can be easily and accurately installed. That is, by aligning and butt-welding the marking lines at the tops of both segment bent pipes, a 90-degree bent pipe can be easily and accurately installed.

[0041] In addition, in the above-described embodiments, markings are formed at four locations inside and outside, top and bottom. However, the number and circumferential positions of the markings are not particularly limited. As long as there is at least one marking, the accuracy of position adjustment during manufacturing and piping can be improved. However, in order to more effectively improve the accuracy of position adjustment during manufacturing and piping, it is preferable to form markings at two locations, top and bottom or inside and outside, and it is more preferable to form markings at four locations, inside and outside, top and bottom.

[0042] Furthermore, in the above-described embodiments, the markings are formed continuously in the pipe axis direction (i.e., with solid lines). However, the markings may be formed intermittently (i.e., with dashed lines). Also, the markings do not necessarily have to be formed over the entire length of the segment bent pipe, and the markings at the ends of the segment bent pipe can also be omitted.

[0043] Note that all of the specific numerical values such as the dimensions and specific shapes mentioned above are merely examples and can be appropriately changed according to the requirements such as the specifications of the product.

Explanation of Reference Numerals

[0044] 10 … Segment bent pipe 16 … Bead portion 18, 22 … Markings 20 … Original pipe 24 … First short pipe 26 … Second short pipe

Claims

1. A segmented curved pipe formed by connecting a plurality of short pipes by butt fusion, a marking line extending in the pipe axis direction is marked on the outer peripheral surface of a straight original pipe, and the end faces of the short pipes produced by cutting the original pipe so that the cutting plane forms a predetermined angle with respect to the marking line are butt-fused with the positions of the marking lines of the adjacent short pipes aligned, the segmented curved pipe, wherein the marking line is formed so as to extend in the pipe axis direction on the outer peripheral surface of the segmented curved pipe except for the bead portion formed during the butt fusion.

2. The segmented curved pipe according to claim 1, wherein the marking lines are formed at four locations, namely, top, bottom, inside, and outside, when the bending direction of the segmented curved pipe is the horizontal direction.

3. The width of the marking line is set to 3% or less of the outer diameter of the segmented curved pipe when the outer diameter of the segmented curved pipe is 355 mm or less, and is set to 2% or less of the outer diameter of the segmented curved pipe when the outer diameter of the segmented curved pipe exceeds 355 mm. The segmented curved pipe according to claim 1 or 2.

4. The segmented curved pipe according to claim 1 or 2, wherein the marking line is formed continuously or intermittently over the entire length of the segmented curved pipe.

5. The segmented curved pipe according to claim 1 or 2, wherein the color difference between the outer peripheral surface of the segmented curved pipe and the marking line is 10 or more.

6. A method for manufacturing a segmented curved pipe formed by connecting a plurality of short pipes by butt fusion, (a) a step of marking a marking line extending in the pipe axis direction on the outer peripheral surface of a straight original pipe, (b) after the step (a), a step of cutting the original pipe so that the cutting plane forms a predetermined angle with respect to the marking line to produce the short pipe, and (c) after the step (b), a method for manufacturing a segmented curved pipe, including a step of butt-fusing the end faces of the short pipes with the positions of the marking lines of the adjacent short pipes aligned.

7. A method for constructing a segmented curved pipe formed by connecting a plurality of short pipes by butt fusion, comprising: (a) A reference line extending in the pipe axis direction is marked on the outer peripheral surface of a straight original pipe, and the end surfaces of the short pipes produced by cutting the original pipe so that the cutting surface forms a predetermined angle with respect to the reference line are butt-fused with the positions of the reference lines of the adjacent short pipes aligned. Two segmented curved pipes are prepared, wherein the reference line is formed so as to extend in the pipe axis direction on the outer peripheral surface of the segmented curved pipe except for the bead portion formed during the butt fusion; and (b) A method for constructing a segmented curved pipe, comprising butt-fusing the end surfaces of the two segmented curved pipes with the positions of the reference lines aligned so that the two segmented curved pipes are connected in a predetermined orientation.

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