JP2019126830A - Metal round pipe, heat exchanger comprising the same, pipe bender and method for bending metal round pipe - Google Patents

Abstract

To provide a metal round pipe capable of suppressing a decrease in cross section of a flexure part or in minimum inner width, obtaining an advantageous point such as reducing a channel resistance, and being manufactured easily and suitably.SOLUTION: A metal round pipe 1 having a flexure part 10 makes an outermost peripheral part 13 of the outside half part 11b of the peripheral wall part 11 of the flexure part 10, in a cross sectional view in the axial direction of the flexure part 10, at the center part in a y direction orthogonal to an inner/outer peripheral direction x of the flexure part 10, and is outwardly convex in a non-arcuate form the distance of which from an intermediate part 15 between a pair of base end parts 14 of the outside half part 11b and the outermost peripheral part 13 to the pipe center O is shorter than the distance La from this outermost peripheral part 13 to the pipe center O.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a metal round pipe in which a bent portion is formed, and a technique related thereto.

  As a heat exchanger tube of a heat exchanger, a metal round pipe having a bent portion such as a U-shaped, meandering or spiral heat exchanger tube is often used. A metal round pipe provided with such a bent portion is manufactured by bending a straight tubular metal round pipe using a pipe bender (see, for example, Patent Documents 1 and 2).

  As the pipe bender, various configurations have been proposed, but many of them are configured to include the roll block 2 and the pressure type 3 in a simplified manner as shown in FIG. Both the roll block 2 and the pressure die 3 have semicircular first and second recesses 21 and 31 for fitting the pipe, and the metal round pipe 1 is sandwiched between the inner surfaces thereof, The metal round pipe 1 is bent so as to be along the first pipe insertion recess 21 of the roll block 2.

According to the above-described means, the metal round pipe 1 having the bent portion 10 as shown in FIG. 7 is obtained. In the bent portion 10 of the metal round pipe 1, the inner half 11a inside the center line C1 has a semicircular arc shape, whereas the wide area of the outer half 11b outside the center line C1 is the center line It is a form depressed toward C1. Of the outer half 11b, the portion Pa of the weir that is originally the outermost part is offset toward the center line C1 by an appropriate dimension Lc.
When the bent portion 10 is formed, the inner half 11a is on the compression side, whereas the outer half 11b is on the pull side. For this reason, as the curvature radius R (bending radius) of the bending portion 10 is reduced, the amount of tensile deformation in the outer half 11b increases, the dimension Lc also increases, and the outer half 11b is flattened. Further, when the bending speed of the metal round pipe 1 is increased, the above-described flattening becomes more remarkable.

  However, according to the prior art, there is room for improvement as described below.

First, when the bending portion 10 is flattened to the above-described form, the cross-sectional area of the bending portion 10 becomes considerably smaller than the original cross-sectional area before bending. In addition, the minimum inner width Ld of the bending portion 10 also decreases. For this reason, the flow path resistance when the fluid is caused to flow through the metal round pipe 1 is increased. This is not preferable when using the metal round pipe 1 as, for example, a heat transfer tube of a heat exchanger.
Second, since the flattening of the bending portion 10 becomes more remarkable as the bending speed of the metal round pipe 1 increases, it is necessary to reduce the bending speed in order to suppress the flattening of the bending portion 10 There is. This causes a disadvantage in enhancing productivity.

  In addition, conventionally, as described in Patent Document 3, for example, when bending a metal round pipe, a metal core is arranged inside the bending target portion to flatten the bent portion. There is a means to prevent it. However, according to such means, the work becomes complicated and the equipment cost becomes high, and when the total length of the metal round pipe is relatively long, or one metal round pipe has a plurality of pieces. In the case where a bending portion is provided, the cored bar cannot be accommodated and arranged inside the portion to be bent, and bending using the cored bar becomes difficult. Therefore, the above-mentioned problems can not be eliminated properly.

JP, 2016-131977, A JP 2012-135797 A JP 2004-322186 A

  The present invention has been conceived under the circumstances as described above, and offers the advantages of suppressing the reduction of the cross-sectional area and the minimum inner width of the bent portion and reducing the flow path resistance. In addition, a metal round pipe that can be easily and appropriately manufactured, a heat exchanger provided with the same, a pipe bender suitable for manufacturing the metal round pipe, and a bending method for the metal round pipe are provided. Is the problem.

  In order to solve the above problems, the present invention takes the following technical means.

  The metal round pipe provided by the first aspect of the present invention is a metal round pipe having a bent portion, and the outer half portion of the peripheral wall portion of the bent portion is a sectional view in the axial direction of the bent portion. A central portion in the y direction orthogonal to the inner and outer peripheral direction x of the bent portion is the outermost peripheral portion, and a pair of base end portions of the outer half portion is more than a distance from the outermost peripheral portion to the pipe center It is characterized by a non-arc-shaped outward convex shape having a shorter distance from an intermediate portion between the outermost portion and the outermost peripheral portion to the center of the pipe.

According to such a configuration, the following effects can be obtained.
First, unlike the prior art, the outer half of the bend is not flat, and the cross-sectional area of the bend can be larger than in the prior art. In addition, the minimum inner width of the bent portion can also be increased. Therefore, the advantage that the flow path resistance when the fluid is circulated through the metal round pipe can be reduced.
Second, although the outer half of the peripheral wall of the bent portion is located closer to the center of the pipe than the outermost portion, the intermediate portion is processed and formed according to such a configuration. In addition, the portion where the depression occurs when the outer half of the bent portion is stretched by being pulled is set as the portion of the intermediate portion, so that the outermost peripheral portion of the outer half is not greatly depressed toward the center of the pipe. Is possible. Because of this, it is possible to increase the bending speed of the metal round pipe, to improve the productivity and to reduce the manufacturing cost, while avoiding the flattening of the bent portion.

  In the present invention, preferably, in the axial direction sectional view of the bent portion, the inner half portion of the peripheral wall portion of the bent portion has a semicircular arc shape or a substantially semicircular arc shape closer to a semicircular arc than the outer half portion. is there.

  According to such a configuration, the cross-sectional area and the minimum inner width of the bent portion can be increased, and the flow path resistance can be reduced.

  In the present invention, it is preferable that the outermost peripheral portion and the intermediate portion of the outer half portion have an outwardly convex curved shape or a non-curved shape in an axial sectional view of the bent portion.

  According to such a configuration, in processing the bent portion, it is more preferable in order to suppress large depression of the outermost peripheral portion and the middle portion of the outer half near the center of the pipe.

  The heat exchanger provided by the second aspect of the present invention is a heat exchanger comprising a heat transfer tube, wherein the heat transfer tube is a metal round pipe provided by the first aspect of the present invention. It is characterized in that it is configured using

  According to such a configuration, the same effect as described for the metal round pipe provided by the first aspect of the present invention can be obtained.

  The pipe bender provided by the third aspect of the present invention includes a roll block in which a first pipe fitting recess for fitting the inner side of the metal round pipe in the bending direction is formed on the outer circumferential surface, and the metal And a pressure type in which a second pipe fitting recess for fitting the outer surface of the round pipe in the bending direction is formed on the side surface, and each of the first and second pipe fitting recesses A pipe bender capable of forming a bent portion in the metal round pipe by sandwiching the metal round pipe by an inner surface, wherein the second pipe fitting recess is the second The central portion in the opening width direction of the pipe fitting recess is the deepest portion, and the distance from the deepest portion to the center between the pair of edges of the second pipe fitting recess is more than the above Innermost part and the pair of edges Is characterized in that towards the middle portion between the mutual distance to the center is a short section non semicircular with.

  The metal round pipe bending method provided by the fourth aspect of the present invention includes a roll block in which a first pipe insertion recess is formed on the outer surface, and a second pipe insertion recess on the inner surface. Using a pipe bender having a pressure type having a formed therein, and holding and bending a metal round pipe by the inner surfaces of the first and second pipe fitting recesses. A method for bending a metal round pipe, characterized in that the pipe bender provided by the third aspect of the present invention is used as the pipe bender.

  According to such a configuration, it is possible to appropriately manufacture the metal round pipe provided by the first aspect of the present invention.

  In the present invention, preferably, the first pipe fitting recess is semicircular in cross section, or substantially semicircular in cross section closer to a semicircular cross section than the second pipe fitting recess.

  According to such a configuration, the inner half portion of the bent portion of the metal round pipe can have a semicircular arc shape or a substantially semicircular arc-like cross-sectional shape closer to the semicircular arc shape than the outer half portion.

  In the present invention, preferably, the deepest portion and the middle portion of the second pipe fitting concave portion are concavely curved or non-curved in a cross sectional view.

  According to such a configuration, it is possible to prevent the outermost peripheral portion and the intermediate portion of the outer half portion of the bent portion of the metal round pipe from being greatly depressed.

  Other features and advantages of the present invention will become more apparent from the description of the embodiments of the present invention given below with reference to the attached drawings.

(A) is a principal part top view which shows an example of the metal round pipe which concerns on this invention, (b) is Ib-Ib expanded sectional drawing of (a). (A) is a schematic plane sectional view which shows an example of the pipe vendor which concerns on this invention, (b) is IIb-IIb sectional drawing of (a), (c) is IIc- of (a). It is IIc sectional drawing. (A) is a general | schematic plane sectional view in the state which set the metal round pipe to the pipe bender shown in FIG. 2, (b) is IIIb-IIIb sectional drawing of (a). FIG. 4 is a schematic plan sectional view showing a state in which a bent portion is formed on a metal round pipe by operating a pipe bender from the state shown in FIG. 3. (A) is a plane sectional view showing an example of a heat exchanger constituted using a metal round pipe which has a bent part, (b) is a Vb-Vb sectional view of (a), c) is a side view. It is principal part sectional drawing which shows an example of the prior art of a pipe bender. (A) is a principal part top view which shows an example of the prior art of a metal round pipe, (b) is an VIIb-VIIb expanded sectional view of (a).

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.
Elements identical or similar to those in the prior art shown in FIG. 6 and FIG.

  A metal round pipe 1 shown in FIG. 1 is made of, for example, stainless steel, and has a bent portion 10 curved with an appropriate curvature radius R in an angle range of 180 °. As shown in FIG. 5B, the inner half portion 11a (inner side (left side of the center line C1)) of the peripheral wall portion 11 of the bent portion 10 is a semicircular arc shape when the bent portion 10 is viewed in the axial direction. . However, since the inner half portion 11 a is a portion where the peripheral wall portion 11 is compressed, as shown in FIG. 6A, the inner half portion 11 a is formed in a bowl shape having a plurality of raised portions 12.

  On the other hand, the outer half part 11b (outside the center line C1) of the peripheral wall part 11 of the bending part 10 is a non-arc-shaped outward convex shape. More specifically, the outer half portion 11 b is a central portion (center in the vertical direction in the figure) perpendicular to the inner and outer circumferential direction x (the left and right direction in FIG. 1B) of the bent portion 10. A portion through which the line C2 passes is taken as the outermost peripheral portion 13. Here, the distance Lb from the pair of intermediate portions 15 to the pipe center O is shorter than the distance La from the outermost periphery 13 to the pipe center O (the relationship of La> Lb). Here, the intermediate portion 15 is a portion between the pair of base end portions 14 and the outermost peripheral portion 13 of the outer half portion 11b. The pair of base end portions 14 is a portion to be a base end of the outer half portion 11 b and is near the center line C1 of the outer half portion 11 b.

The outermost circumferential portion 13 may be slightly displaced closer to the center O of the pipe than the original position before the bending, by bending the metal round pipe 1 described later. Therefore, the distance from the portion near the proximal end 14 to the pipe center O in the intermediate portion 15 may be longer than the distance La. However, in the present invention, the entire area of the middle part 15 does not have to satisfy the relationship of La> Lb, and at least a part of the middle part 15 (for example, the center part of the middle part 15 or its vicinity) to the pipe center O The distance Lb may satisfy the relationship of La> Lb.
This also applies to the relationship between the distances La ′ and Lb ′ between the innermost part 31c and the innermost part 31c of the second pipe fitting recess 31 of the pressure mold 3 described later.

  Considering from another side, the outer half portion 11b corresponds to a form in which the intermediate portion 15 is located closer to the pipe center O than the arc a passing through the three points of the pair of base end portions 14 and the outermost peripheral portion 13. Do.

  The outermost peripheral portion 13 and the intermediate portion 15 are both curved outwardly convex in a sectional view of the bent portion 10 in the axial direction. These curvature radii r1 and r2 are different, for example, r1 <r2. However, the present invention is not limited to this, and one or both of the outermost peripheral portion 13 and the intermediate portion 15 can be made non-curved, for example.

Next, an example of the pipe bender A for forming the bent portion 10 and an example of a method for forming the bent portion 10 using the same will be described.

  The pipe vendor A shown in FIG. 2 includes a roll block 2, a pressure mold 3, and a clamp mold 4.

  The roll block 2 is horizontally rotatable around the shaft portion 20, and a first pipe fitting recess 21 is formed in series on the outer peripheral surface thereof. In a plan sectional view, the first pipe fitting concave portion 21 has a curved portion 21a curved in an arc shape over an angle range of 180 °, and straight portions 21b and 21c connected to both ends thereof. The first pipe insertion recess 21 corresponds to the above-described inner half 11a of the bent portion 10, and specifically, as shown in FIG. Semicircular arc). However, on the inner surface of the first pipe fitting recess 21, a plurality of recessed groove portions 22 which are deeper than the first pipe fitting recess 21 are provided at appropriate intervals. The concave groove portion 22 is a portion corresponding to the raised portion 12 shown in FIG.

  The pressure die 3 is a block-like member in which the second pipe insertion recesses 31 are formed in a series in the horizontal direction indicated by the arrow Na on the side surface, and is located beside the roll block 2 in the direction of the arrow Na described above. In addition to being able to reciprocate, it also reciprocates in the horizontal direction of the arrow Nb that intersects it, and can approach and leave the roll block 2. The second pipe insertion recess 31 is in a form corresponding to the outer half 11b of the bent portion 10 described above. Specifically, as shown in FIG. 2 (c), the second pipe fitting recess 31 has a central part in the vertical opening width direction as the innermost part 31a, and a second part from the innermost part 31a. The distance Lb ′ from the pair of intermediate portions 31c to the center Oa is shorter than the distance La ′ from the pair of edge portions 31b of the pipe insertion recess 31 to the center Oa. The middle portion 31 c is a portion between each edge 31 b and the deepest portion 31 a. The innermost part 31a and the intermediate part 31c are parts corresponding to the outermost peripheral part 13 and the intermediate part 15 of the bending part 10 shown in FIG. 1, and preferably have a concave curved shape in a sectional view. However, these can also be made non-curved in cross sectional view.

  The clamp die 4 is a part for clamping the metal round pipe 1 between the roll block 2 and causing the metal round pipe 1 to be pulled. A third pipe fitting recess 41 having a semicircular cross section as shown in FIG. 2B is provided on the side surface of the clamp die 4. The clamp die 4 is configured to horizontally rotate around the shaft 20 as the roll block 2 rotates around the shaft 20. As a result, the relative positional relationship with the roll block 2 is prevented from being displaced, and the clamp state of the metal round pipe 1 can be maintained by both the roll block 2 and the clamp die 4.

  The process of forming the bent portion 10 in the metal round pipe 1 using the pipe vendor A described above is performed as follows.

First, as shown in FIG. 3, the metal round pipe 1 has the inner side in the bending direction fitted into the first pipe fitting recess 21 (straight portion 21 b) of the roll block 2, while the outer side in the bending direction is a pressure type. 3 and the clamp mold 4 are set so as to be fitted into the second and third pipe fitting recesses 31 and 41. The pressure die 3 and the clamp die 4 are brought close to the roll block 2 side, and the metal round pipe 1 is clamped with a sufficient force so as not to cause sliding or the like between these and the metal round pipe 1. Next, in such a setting state, the roll block 2 and the clamp die 4 are horizontally rotated by 180 ° around the shaft portion 20. As a result, as shown in FIG. 4, a portion of the metal round pipe 1 is bent along the curved portion 21 a of the first pipe fitting concave portion 21 of the roll block 2 to form the bent portion 10. Is done. The bent portion 10 has the same configuration as that described with reference to FIG. When the roll block 2 and the clamp die 4 are rotated as described above, the pulling force or the pulling amount of the outer half 11b of the bending portion 10 can be adjusted by moving the pressure die 3 forward in the direction of the arrow Nc. is there.

  FIG. 5 shows an example of the heat exchanger HE. The plurality of heat transfer tubes 1A of the heat exchanger HE are entirely formed by forming a plurality of bent portions 10 on the metal round pipe 1 as described above. A serpentine heat transfer tube. In the heat exchanger HE, a plurality of heat transfer tubes 1A are accommodated in the case 5 in a state where they are stacked at intervals in the vertical direction. The case 5 is provided with an air supply port 50 and an exhaust port 51 for the combustion gas as the heating gas. The end of each heat transfer tube 1A is disposed in the headers 6a and 6b for water entry and discharge, and the hot and cold water supplied from the water inlet 60a of the header 6a passes through each heat transfer tube 1A and is heated. It reaches into the header 6b, and it is comprised so that a hot water may come out from the outlet 60b.

  Next, the operation of the metal round pipe 1 shown in FIG. 1 will be described.

  First of all, the bending portion 10 is not made into a largely flat shape as well as the inside half 11a as well as the outside half 11b. For this reason, compared with the prior art shown in FIG. 7, it is possible to increase the cross-sectional area and the minimum inner width of the bent portion 10. Therefore, it is possible to reduce the flow path resistance when the fluid is caused to flow through the metal round pipe 1. This is preferable in reducing the water flow resistance of the heat transfer tube 1A of the heat exchanger HE shown in FIG.

The outer half portion 11 b of the bending portion 10 has a configuration in which the middle portion 15 is positioned closer to the pipe center O than the outermost peripheral portion 13. Such a shape is a bending portion when forming the bending portion 10. The part which produces a hollow (displacement near the pipe center O) by being pulled and extended by the outer half part 11b of 10 is the form made into the intermediate part 15. Therefore, it is possible to prevent the outermost peripheral portion 13 of the outer half portion 11b from being greatly recessed toward the pipe center O. From such a thing, even when the bending speed of the metal round pipe 1 is made relatively high, it is possible to appropriately avoid the flattening of the bent portion 10.
In the present embodiment, as described above, the outermost peripheral portion 13 and the intermediate portion 15 of the outer half portion 11b of the bending portion 10 are both curved outward convex in the axial direction sectional view of the bending portion 10 Therefore, it is more reliably prevented that these portions are greatly recessed near the pipe center O.

The present invention is not limited to the contents of the embodiments described above. Metal round pipe according to the present invention,
The specific configuration of each part of the heat exchanger and the pipe bender can be variously modified within the intended scope of the present invention. The specific configuration of each operation process of the method of bending a metal round pipe according to the present invention can be variously modified within the intended scope of the present invention.

  The present invention focuses on preventing or suppressing flattening of the outer half of the bent portion of the metal round pipe. Therefore, it is possible to select the specific shape of the inner half according to various circumstances. However, it is preferable that the inner half is in a semicircular arc shape or a form (substantially semicircular arc shape) closer to the semicircular arc than at least the outer half.

  Although it is preferable to make the outermost periphery and the middle part of the outer half of the bent portion be curved outward convex, or at least non-curved, and formed into an inwardly concave curved shape, it is preferable to do so In this case, if it is within the range of the shape intended by the present invention, it belongs to the technical scope of the present invention.

The specific bending angle of the bent portion is not limited. In the embodiments described above, the bends are formed at an angle range of 180 °, but instead, other angles such as 90 ° may be used. Further, the specific bending radius, the size and material of the metal round pipe to be bent are not limited.
The metal round pipe to which the present invention is applied is suitable for use as a heat transfer tube of a heat exchanger, but can also be used for other applications.

A pipe bender O pipe center Oa center (center between a pair of edges)
HE Heat exchanger 1 Round pipe 1A made of metal Heat transfer tube 10 Bending part 11 Peripheral wall part 11a Inner half part 11b Outer half part 13 Outermost part (of outer half part)
14 Base end (outside half)
15 middle part (between the proximal end of the outer half and the outermost part)
2 Roll block 21 first pipe fitting recess 3 pressure type 31 second pipe fitting recess 31 a deepest part (of the second pipe fitting recess)
31b edge (of the second pipe recess)
31c Middle part (between the innermost part and the edge)

Claims (8)

A round metal pipe with a bend,
In the axial direction sectional view of the bent portion, the outer half portion of the peripheral wall portion of the bent portion has a central portion in the y direction orthogonal to the inner and outer peripheral direction x of the bent portion as the outermost peripheral portion. A non-arc shaped outward facing in which the distance from the middle portion between the pair of base end portions of the outer half portion to the outermost portion is shorter than the distance from the outer peripheral portion to the pipe center Metal round pipe characterized by being convex. A metal round pipe according to claim 1, wherein
The metal round pipe, wherein an inner half portion of a peripheral wall portion of the bent portion has a semicircular arc shape or a substantially semicircular arc shape closer to a semicircular arc shape than the outer half portion in the axial direction sectional view of the bent portion. A metal round pipe according to claim 1 or 2, wherein
The metal round pipe, wherein the outermost peripheral portion and the middle portion of the outer half portion are curved outward convex or non-curved in an axial sectional view of the bent portion. A heat exchanger comprising a heat transfer tube,
The heat exchanger according to any one of claims 1 to 3, wherein the heat transfer tube is configured by using the metal round pipe. A roll block having a first pipe insertion recess formed on an outer peripheral surface for inserting the bending direction inner surface side of a metal round pipe;
A pressure type in which a second pipe fitting recess for fitting the outer surface side in the bending direction of the metal round pipe is formed on the side surface;
Equipped with
A pipe bender capable of forming a bent portion in the metal round pipe by sandwiching the metal round pipe by the inner surfaces of the first and second pipe fitting concave portions, ,
In the second pipe fitting recess, the central part in the opening width direction of the second pipe fitting recess is the deepest part, and a pair of edges of the second pipe fitting concave from the deepest part The distance from the middle part between the innermost part and the pair of edge parts to the center is shorter than the distance to the center between the parts, and the cross section is semi-circular. Characteristic pipe vendor. The pipe vendor according to claim 5,
The pipe bender according to claim 1, wherein the first pipe fitting recess is semicircular in cross section or substantially semicircular in cross section closer to a semicircular cross section than the second pipe fitting recess. The pipe vendor according to claim 5 or 6, wherein
The pipe bender, wherein the deepest part and the middle part of the second pipe fitting concave portion have a concave curved shape or a non-curved shape in a cross sectional view. Utilizing a pipe bender provided with a roll block having a first pipe fitting recess formed on the outer side, and a pressure type having a second pipe fitting recess formed on the inner side,
A method for bending a metal round pipe, comprising the steps of holding and bending a metal round pipe by the inner surfaces of the first and second pipe fitting recesses,
A method for bending a metal round pipe, characterized by using the pipe bender according to any one of claims 5 to 7 as the pipe bender.

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