JPH09178382A - Grooved heat transfer tube and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grooved heat transfer tube capable of achieving a higher efficiency of heat exchange as compared with the conventional grooved heat transfer tube and further provide a method capable of easily and efficiently manufacturing the above heat transfer tube. SOLUTION: A large number of grooves 7, 8 extending in a longitudinal direction are formed in a bar-shaped metal plate and then the metal plate is rolled with one face having the grooves 8 being directed outward to make two end portions oppose to each other, and a tube is formed by jointing the two end portions by butt welding to thereby produce a heat transfer tube 1 having a large number of the grooves 7, 8 extending in the direction of an axis thereof (O) in outer and inner circumferential faces of a metal tube. An ungrooved portion 9 having no groove 8 is formed along the axis (O) in the metal tube and the grooves 8 are formed in the direction crossing the ungrooved portion 9. The grooves 7, 8 are spirally formed around the axis (O), extending in directions opposite to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer tube used in various heat exchangers, and more particularly to a grooved heat transfer tube in which grooves are formed in order to enhance heat exchange efficiency, and a method for manufacturing the same. is there.

[0002]

2. Description of the Related Art In a metal heat transfer tube used as an evaporation tube or a condensation tube in a heat exchanger such as an air conditioner or a refrigerator, a large number of metal tubes are provided on the inner peripheral surface of the metal tube in order to increase the heat exchange efficiency. The so-called heat transfer tube with an inner surface groove, in which grooves are formed or a large number of fins are formed on the inner peripheral surface so that the grooves are defined between these fins, is becoming popular. This type of heat transfer tube with an inner groove, which is currently the mainstream, is a seamless tube formed by drawing or extruding, and a floating plug with a spiral groove formed on the outer surface allows the inner circumference of the tube to pass. It is manufactured by a method of forming a groove by rolling a spiral fin over the entire surface.

[0003]

However, in the heat transfer tube with an inner groove formed by such a manufacturing method, the shape and height of the fin are limited due to the characteristics of the floating plug. Therefore, the fin is improved to improve the heat transfer tube. There is naturally a limit to improving heat exchange efficiency. Further, in a heat transfer tube using such a floating plug, in order to improve heat exchange efficiency, a dimple having a projection shape is provided on the inner surface of the tube, and
It is also proposed to knurl the outer peripheral surface of the pipe into a sawtooth shape, but even with such a heat transfer tube, since the inner surface of the pipe is simply dimple processing, a significant improvement in heat exchange efficiency cannot be expected and the processing cost is high. There is a problem that it becomes expensive.

On the other hand, irrespective of the method of passing a floating plug through such a seamless pipe, grooves or fins are formed on one surface of a long metal sheet material by rolling with a grooved roll. The plate material is rolled in the width direction so that the surface of the side faces inward, and its both side edges are abutted, and thereafter, both side edges are heated by an induction current and welded,
A method of manufacturing a heat transfer tube with an inner groove using a so-called electric resistance welded tube method, which is formed into a tubular shape, has also been proposed. According to such a method, grooves or fins can be formed in a flat plate material. Therefore, a high degree of freedom in design can be obtained, and the heat exchange efficiency of the manufactured heat transfer tube can be improved. However, recently, there has been an increasing demand for further improvement in performance of the heat exchangers as described above, and accordingly, heat transfer tubes used in the heat exchangers have been further improved in heat exchange. There is a growing demand for improved efficiency.

The present invention has been made under such a background, and provides a grooved heat transfer tube capable of obtaining high heat exchange efficiency as compared with a conventional inner surface grooved heat transfer tube, and It is an object of the present invention to provide a manufacturing method capable of manufacturing such a heat transfer tube easily and efficiently.

[0006]

In order to solve the above problems and achieve the above object, a grooved heat transfer tube of the present invention is provided on the inner peripheral surface and the outer peripheral surface of a metal tube in the axial direction of the metal tube. It is characterized in that a large number of grooves extending toward the outer peripheral surface of the pipe are formed, and the surface area is increased by forming the groove on the outer peripheral surface of the pipe. The heat exchange efficiency is improved by acting on the medium existing on the outside of the. Here, in the metal pipe, a grooveless portion in which a groove is not formed is formed along the axial direction, and the groove is formed in a direction intersecting the grooveless portion, the groove is formed in the grooveless portion. Since the medium is opened, the medium introduced into the groove and used for heat exchange is quickly discharged from the groove and circulated, and the heat exchange efficiency can be further improved.

Further, by forming the groove formed on at least the outer peripheral surface of the metal tube so that the groove width becomes gradually smaller toward the outer peripheral side, the medium used for heat exchange is formed in the groove. Since it is possible to surely hold it, it is possible to promote further improvement of the heat exchange efficiency. Further, by forming the groove formed on the inner peripheral surface of the metal pipe and the groove formed on the outer peripheral surface in a spiral shape extending in opposite directions around the axis, these grooves intersect with each other. Thus, it is possible to prevent a situation in which the strength of the pipe is impaired by forming grooves on both inner and outer peripheral surfaces of the pipe.

On the other hand, in the method for manufacturing a grooved heat transfer tube of the present invention, a large number of grooves extending in the longitudinal direction of the plate material are formed on at least one surface of the metal plate material, and then The sheet material is rolled into the width direction so that one surface faces outward, and the side edges of the sheet material are opposed to each other, and then the side edges are abutted and joined together to form a tubular shape. By forming a groove in the flat plate-shaped strip material in this way and then forming this plate-shaped strip material in a tubular shape, the groove is formed on the outer peripheral surface as described above without impairing the design freedom of the groove. It is possible to continuously manufacture the heat transfer tube thus prepared.
The groove is formed by directly forming a groove on the one surface serving as the outer peripheral surface of the metal tube, and by forming a large number of fins on the one surface to define the groove between the fins. You may do it.

[0009]

1 to 3 show a first embodiment of a grooved heat transfer tube according to the present invention. The grooved heat transfer tube 1 of the present embodiment is made of copper or copper alloy such as phosphorus deoxidized copper (eg, JIS1220 alloy) or oxygen-free copper, which is generally used as a material for the heat transfer tube, or aluminum, aluminum alloy, or steel material. The main body is a substantially circular metal tube 2, and a large number of fins 4 ... Are formed on the inner peripheral surface 3 of the metal tube 2 so as to extend in the central axis O direction of the metal tube 1. Similarly, a large number of fins 6 ... Are formed on the outer peripheral surface 5 of the metal tube 2 so as to extend in the direction of the axis O. Further, between the fins 4, 4 ... and the fins 6, 6 ... Which are adjacent to each other in the circumferential direction of the metal tube 2, the grooves 7 ... 8 ... will be defined.

Here, the fins 4, ..., 6 ... Are arranged at equal intervals in the circumferential direction so as to be radial around the axis O in the cross section of the heat transfer tube 1 orthogonal to the axis O. The cross-sections of the individual fins 4 and 6 are formed in a substantially isosceles triangular shape that is tapered as they protrude from the inner peripheral surface 3 or the outer peripheral surface 5 of the metal tube 2 to the radial inner peripheral side or outer peripheral side with respect to the axis O. ing. The outer fin 6
The outer peripheral surface from 5 height H ₆ and the inner peripheral side of the height H ₄ from the inner circumferential surface 3 of the fin 4, i.e. the depth of the inner peripheral groove 7 and the outer circumferential groove 8, Ya size of the heat transfer tube 1 The height H ₄ of the inner fins 4 may be larger than the height H ₆ of the outer fins 6 depending on the material, application, etc. The height H ₆ of the fins ₆ may be larger than the height H ₄ of the inner fins 4,
Further, the heights H ₄ and H _{6 of} both fins 4 and 6 may be the same. Further, the number and intervals of the fins 4, ..., 6 are similarly set as appropriate. Except that the groove widths W ₇ and W ₈ of the grooves 7 ...
Will also be set equal to each.

Further, in this embodiment, these fins 4 are used.
, 6 ... are formed in a spiral shape twisting around the axis O about the axis O at twist angles α and β, respectively, and the direction of the twist is such that the fins 4 ... The fins 6 of the surface 5 are arranged in opposite directions. Therefore, the grooves 7 ..., 8 ... defined between these fins 4 ..., 6 ... are also twisted in opposite directions at the twist angles α, β about the axis O in the present embodiment, as shown in FIG. The metal tube 2 is formed in a spiral shape and intersects with each other in a lattice shape in the perspective view of the metal tube 2 as shown in FIG. In addition, in the present embodiment, the sizes of the twist angles α and β of the grooves 7 and 8 are set to be equal to each other, but the sizes are different from each other depending on the size of the heat transfer tube 1 and the application. May be

Furthermore, in this embodiment, the metal tube 2 is also used.
On the inner and outer peripheral surfaces 3 and 5, portions where the fins 4 and 6 are not formed, that is, the grooveless portions 9 where the grooves 7 and 8 are not formed, respectively.
Are formed so as to extend parallel to the axis O.
The grooveless portion 9 is a portion that serves as a joint portion when electric resistance welding of the metal tube 2 is performed by an induced current described later, and on the outer peripheral surface 5 side, a cylindrical surface that is substantially equal to the outer diameter surface of the metal tube 2. On the other hand, on the inner peripheral surface 3 side, a welded portion 10 formed by electric resistance welding is formed at the center of the inner peripheral surface 3 so as to rise to the inner peripheral side. Further, since the grooveless portions 9 are formed parallel to the axis O with respect to the fins 4 and 6 which are twisted around the axis O, the fins 4 ..., 6 ... , Β, so that the grooves 7 ..., 8 ... Defined between the fins 4 ,. Both ends are open to the grooveless portion 9.

The grooved heat transfer tube 1 having such a structure is shown in FIG.
It is manufactured by an embodiment of the manufacturing method of the present invention using the manufacturing apparatus as shown in FIG. Reference numeral 11 in FIG. 4 denotes an uncoiler that continuously feeds a metal strip T having a constant width, and the strip T that has been fed out passes through a pair of pressing rolls 12, 12 and It is passed between the grooved rolls 13 and 14 as shown in FIG. Spiral grooves 13A ..., 14A ... Are formed on the outer peripheral surfaces of these grooved rolls 13 and 14 in accordance with the twist angles α and β of the fins 4 and 6, and both rotating grooved rolls 13 and 14 are formed. By pressing through the strip material T between these spiral grooves 1
3A ..., 14A ... Are transferred to both sides of the strip material T, and the fins 4 ... 6 are formed on the strip material T as shown in FIG.
... are continuously rolled, and the grooves 5 ..., 7 ... Are defined between these fins 4. In addition, spiral grooves 13A and 14A are provided on both side edges of the grooved rolls 13 and 14, respectively.
Is not formed, and therefore both side edges S of the strip T,
The fins 4 and 6 are not formed on S.

In this way, the plate material T in which the fins 4 ..., 6 ... Are rolled by the grooved rolls 13, 14 and grooved is
Then, after passing through a pair of rolls 15 and 15, a plurality of pairs of forming rolls 16 are passed through, and one face F ₁ on which the fins 6 ... Are formed by the grooved roll 14 faces outward during this period. Then, it is gradually rolled in the width direction, and immediately after passing through the forming roll 16, it is formed into an upwardly opening C-shaped section in which both side edges S, S face each other. .
The rolled sheet material T is passed through the induction heating coil 18 by an induction current after the gap between the opposing side edges S and S is kept constant by the rolling separator 17. The side edges S, S are heated and then passed through a pair of squeeze rolls 19, 19 and pressed from both sides, so that the heated side edges S, S are butted and welded to each other to form a substantially circular shape. It is formed into a tubular shape.

Further, on the outer peripheral surface 5 of the heat transfer tube 1 thus welded, a bead is formed by the molten material protruding from the opposite side edges S, S abutted with each other, and this bead is cut by the bead cutter 20. As a result, the substantially grooveless portion 9 having a substantially cylindrical surface is formed at the abutting portion of the side edge portions S, S. Further, on the inner peripheral side of the grooveless portion 9, the swelling due to the welding of the side edge portions S, S is left as it is, and the weld portion 10 is formed. Then, the heat transfer tube 1 with the bead thus cut is passed through the cooling tank 21 to be forcibly cooled, and then passed through the sizing rolls 22 arranged in plural pairs to be reduced in diameter to a predetermined outer diameter. After that, it is taken up by the rough coiler 23.

However, in the grooved heat transfer tube 1 of the above-described embodiment manufactured as described above, the fins 6 form grooves 8 on the outer peripheral surface 5 of the heat transfer tube 1 as compared with the conventional inner surface grooved heat transfer tube. Since it is formed, the surface area of the heat transfer tube 1 to be used for heat exchange is significantly increased, which makes it possible to significantly improve the heat exchange efficiency. Further, by forming the grooves 8 on the outer peripheral surface 5 in this manner, the grooves 8 ... Work on the medium existing outside the heat transfer tube 1, and further improvement of the heat exchange efficiency is promoted. For example, when the heat medium vapor is supplied to the outside of the heat transfer tube 1 to be condensed, the heat medium vapor flowing outside the tube 1 is made into a turbulent flow by the fins 6 between the grooves 8 ... The fins 6 ... Can be used as aggregation nuclei to improve the condensation efficiency and promote liquefaction, and the condensed heat medium liquid can be efficiently used in the longitudinal direction of the heat transfer tube 1 by utilizing the surface tension in the grooves 8. It becomes possible to increase the reflux effect by flowing.

On the other hand, on the contrary, in the case where the heat medium liquid is supplied to the outside of the heat transfer tube 1 to be evaporated, the edges in the grooves 8 ... serve as evaporation nuclei for generating bubbles and promote nucleate boiling to be vaporized. The efficiency can be improved, and the heat medium liquid can be efficiently circulated in the longitudinal direction of the heat transfer tube 1 by utilizing the surface tension in the grooves 8 to increase the supply effect. Therefore, by using the grooved heat transfer tube 1 of the present embodiment, it is possible to achieve a high heat exchange efficiency in a heat exchanger or the like as described above, and thus a recent demand for further improvement in performance of such a heat exchanger or the like. It will be possible to fully cope with.

Further, in the present embodiment, the grooveless portion 9 is formed on the outer peripheral surface 5 of the heat transfer tube 1, and the grooves 8 ... Helically formed on the outer peripheral surface 5 are provided on the grooveless portion 9. It is designed to intersect and be divided and open. Therefore, the heat medium liquid or the like introduced into the grooves 8 and subjected to heat exchange is promptly discharged from the grooves 8 through the grooveless portion 9 and also from the grooveless portion 9 into the grooves 8. A heat medium liquid or the like can be introduced for heat exchange. Therefore, according to this embodiment, it is possible to efficiently circulate and supply the heat medium in combination with the above-mentioned circulation due to the surface tension in the grooves 8 and the improvement of the supply effect, and further heat exchange. It can promote the improvement of efficiency.

Further, in the present embodiment, the grooves 7 formed on the inner peripheral surface 3 of the metal tube 2 and the grooves 8 formed on the outer peripheral surface 5 have opposite twist directions of the fins 4 and 6. Accordingly, the grooves 7 are formed in a spiral shape extending in opposite directions around the axis O, so that the both grooves 7, ..., 8 intersect in a grid pattern in the perspective view of the metal tube 2 as described above. Will be arranged as follows. Therefore, the portion where the wall thickness of the heat transfer tube 1 becomes thin due to the overlapping of the groove 7 and the groove 8 is only at the intersection point of the lattice, and for example, the groove 7 ... And the groove 8 ...
It extends around in the same direction, or both grooves 7
Compared with the case where the ..., 8 ... are formed so as to overlap over the entire length thereof, the thinned portion of the heat transfer tube 1 can be dispersed as little as possible, and such a thin portion It is possible to prevent a situation in which the strength of the heat transfer tube 1 is impaired or the plate material T is deformed from a predetermined tube shape during the forming by the forming roll 16 or the like. .

On the other hand, in the above embodiment of the manufacturing method of the present invention, when manufacturing the grooved heat transfer tube 1 as described above, the grooves 7, ..., 8 ... Are formed on both surfaces of the flat plate material T. Then, an electric resistance welded pipe system is adopted in which the plate material T is rolled and the both side edges are joined to form a tubular shape. Therefore, since the grooves 7 and 8 can be formed in the flat plate material T in this manner, the degree of freedom in designing the groove can be improved as compared with the case where the groove is directly formed in the seamless pipe. Further, the heat transfer tube 1 exhibiting the high heat exchange efficiency as described above can be relatively easily manufactured without impairing the degree of freedom in designing the groove even in the conventional method for manufacturing the heat transfer tube with the inner groove by the electric resistance welded pipe method. It becomes possible.

Further, in this embodiment, as shown in FIG. 4, the sheet material T is supplied from the uncoiler 11 to feed the grooved roll 1
Grooving with 3 and 14, then forming roll 1
After rolling the strip material T by 6 and joining both side edges S of the strip material T by the induction heating coil 18, the bead cutter 20 scrapes off the bead, and then the cooling tank 2
Rough coiler 23 through 1 and sizing roll 22
Since the steps up to winding can be continuously performed, it is possible to promote efficient production of the heat transfer tube 1.
Further, in the present embodiment, instead of performing groove processing on one surface of the strip material in the rolling process in the conventional electric resistance welded pipe method, a pair of grooved rolls 13 and 14 are provided on both surfaces of the strip material T. Simply by grooving, the metal tube 2 as described above
Since it is possible to manufacture the heat transfer tube 1 in which the grooves 7 and 8 are formed on the inner and outer peripheral surfaces 3 and 5, there is almost no need to modify the other steps. It can be done more efficiently and easily using equipment. In the rolling process of the present embodiment, instead of the grooved roll 13 that performs groove processing on the other surface F ₂ that becomes the inner peripheral surface 3 of the heat transfer tube 1, a smooth groove in which the spiral groove 13A is not formed is formed. If a roll is used, it becomes possible to manufacture the heat transfer tube in which the groove 8 is formed only on the outer peripheral surface 5 by the electric resistance welded pipe method.

Next, FIG. 8 shows a second embodiment of the grooved heat transfer tube of the present invention. The parts common to the first embodiment shown in FIGS. 1 to 3 are the same. Will be assigned and the description thereof will be omitted. In the heat transfer tube 31 according to the second embodiment, the fins 32 formed on the outer peripheral surface 5 of the metal tube 2 are not radially centered on the axis O in a cross section orthogonal to the axis O, and the tips thereof are not provided. The portion is formed so as to curve toward one circumferential direction of the metal tube 2 as it goes toward the outer peripheral side, whereby the fins 32 ...
It is characterized in that the groove width W ₃₃ of the grooves 33 defined between them is formed so as to become gradually smaller toward the outer peripheral side. The direction in which the fins 32 are curved may be the same as the direction in which the fins 32 are twisted around the axis O, or may be the opposite direction.

However, the heat transfer tube 3 thus constructed
According to the first aspect, since the groove width W _{33 of the} groove 33 formed on the outer peripheral surface 5 is formed in a tunnel shape so as to become smaller toward the outer peripheral side, the heat medium once introduced into the groove 33 can be reliably grooved. Three
It is possible to hold it in 3 and use it for heat exchange, which makes it possible to promote more efficient heat exchange.
Note that the grooves 33 ... Include the grooveless portions 9 as in the first embodiment.
Therefore, the medium used for the heat exchange is opened in the groove 33.
Since it does not stay inside and is quickly discharged through the grooveless portion 9, the heat exchange efficiency is not impaired. Further, particularly when the heat transfer tube 31 is used in the evaporation portion of the heat medium liquid supplied to the outside as described above, bubbles are likely to be generated inside the tunnel-shaped groove 33, and the bubbles are cores. Therefore, there is an advantage that the evaporation is promoted, and as a result, the vaporization efficiency of the heat carrier liquid is significantly improved. When the emphasis is placed on the evaporation nucleation effect by the bubbles, the fins 32 may be deformed so as to be in close contact with each other so that the grooves 33 have a crushed shape. Further, since the tunnel-shaped groove portion 33 increases the transport efficiency of the liquid due to the surface tension in the groove portion 33, there is an advantage that the overall heat transfer performance is significantly improved.

On the other hand, in the first and second embodiments described above, the grooves 8 and 33 formed on the outer peripheral surface 5 of the heat transfer tubes 1 and 31 are spiral grooves 1 on the grooved roll 14 in the rolling process.
4A is formed to form a large number of fins 6 ..., 32 ... On the outer peripheral surface 5, and between these fins 6 ... However, like the grooved heat transfer tube 41 according to the third embodiment of the present invention shown in FIG. 9, a large number of grooves 42 are directly formed on the outer peripheral surface 5 of the metal tube 2. May be formed. However, also in the third embodiment shown in FIG. 9, the same parts as those in the first and second embodiments are designated by the same reference numerals. Such a heat transfer tube 41
For example, in the rolling step of the embodiment according to the manufacturing method of the present invention, instead of the grooved roll 14 in which the spiral groove 14A is formed, the groove 42 is formed on the one surface F ₁ of the plate-shaped material T. It can be manufactured by using a roll on which a large number of ridges for forming the ridge are formed.

However, in such a heat transfer tube 41, the heat transfer tube 1 is different from the case where the grooves 8 ..., 33 ... Are defined between the fins 6 ,. Since the thickened portions of the metal pipe 2 corresponding to the fins 6 and 32 of the heat transfer pipes 31, 31 can be relatively large, it is possible to further secure the strength of the heat transfer pipe 41. Become. Further, since the fins are not crushed or deformed when passing through the forming roll 16 or the sizing roll 22, the predetermined groove shape is maintained and the above-mentioned groove 42 ... The effect can be more reliably exhibited. Further, if the grooves 42 of the outer peripheral surface 5 of the metal tube 2 are formed so as to match the positions of the fins 4 formed on the inner peripheral surface 3 as shown in the figure, the plate-shaped material T is formed by groove processing by rolling. It is also possible to obtain a merit that the portion that is deformed can be made as small as possible and the influence of residual stress and the like due to the deformation can be suppressed.

Furthermore, in the above-mentioned first to third embodiments, both sides F ₁ and F ₂ of the sheet material T are rolled by a pair of grooved rolls 13 and 14, respectively, so as to form a metal sheet. The fins 4 and the grooves 7 formed on the inner peripheral surface 3 of the tube 2 or the fins 6, 32 and the grooves 8, 33, 42 formed on the outer peripheral surface 5 are formed in spiral shapes parallel to each other. However, for example, this is applied to both sides F ₁ and F ₂ of the strip material T.
For at least one of the above, the rolling is performed in two or more steps by a plurality of grooved rolls having different spiral groove twist angles, and the fin is formed by the second rolling on the fin formed by the first rolling. It is also possible to form fins or grooves that intersect with. FIG. 10 shows a fourth embodiment of the present invention in which the _one surface F ₁ of the plate material T is thus rolled in two steps.
It is a development view of the outer peripheral surface 5 of the heat transfer tube 51 according to the first embodiment, and the same reference numerals are given to the portions common to the first embodiment. In this heat transfer tube 51, the fins 6 ... Are formed over the entire surface of the outer peripheral surface 5 where the fins 6 are formed.
Grooves 52 having a V-shaped cross section intersecting with each other are formed, and the fins 6 are shortly divided by these grooves 52, and overhang portions 53 are formed on both sides of the groove 52.

However, according to the heat transfer tube 51 having such a structure, the effects common to the first to third embodiments can be obtained, and the overhang portion 53 is formed so that these effects can be obtained. A narrow groove is formed on the lower side of the overhang portion 53, and nucleate boiling of the heating medium is promoted by the narrow groove, so that there is an advantage that the boiling efficiency can be increased. The fourth shown in FIG.
In the embodiment, the outer peripheral surface 5 of the heat transfer tube 51 is rolled in two steps to form the fins 6 ... And the grooves 52. The fins or grooves may be formed, or the inner peripheral surface 3 of the heat transfer tube 51 may be similarly formed with a plurality of fins or grooves intersecting each other.

[0028]

As described above, according to the grooved heat transfer tube of the present invention, the groove is formed on the outer peripheral surface of the metal tube so that the surface area is increased and the groove on the outer peripheral surface is increased. Acts on the medium existing outside the tube, so that the heat exchange efficiency can be improved as compared with the conventional heat transfer tube with an inner groove. Therefore, it is possible to provide a heat transfer tube that can sufficiently meet the recent demand for further improvement in performance of heat exchangers and the like. Further, according to the grooved heat transfer tube manufacturing method of the present invention, a heat transfer tube exhibiting such excellent heat exchange efficiency,
It becomes possible to manufacture efficiently and easily using the conventional electric resistance welded pipe manufacturing equipment.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a grooved heat transfer tube of the present invention.

FIG. 2 is a partially cutaway perspective view showing the outline of the first embodiment shown in FIG.

FIG. 3 is a development view of an outer peripheral surface 5 of the first embodiment shown in FIG.

FIG. 4 is a schematic view showing a manufacturing apparatus according to an embodiment of a method for manufacturing a grooved heat transfer tube of the present invention.

FIG. 5 is a schematic view of the manufacturing apparatus shown in FIG.
FIG.

6 is a side view of the grooved rolls 13 and 14 shown in FIG.

FIG. 7: Grooved rolls 13, 1 shown in FIGS. 5 and 6
4 is a cross-sectional view of a plate-shaped material T grooved by 4.

FIG. 8 is a sectional view showing a second embodiment of the grooved heat transfer tube of the present invention.

FIG. 9 is a sectional view showing a third embodiment of the grooved heat transfer tube of the present invention.

FIG. 10 is a development view of an outer peripheral surface 5 showing a fourth embodiment of the grooved heat transfer tube of the present invention.

[Explanation of symbols]

1,31,41,51 Heat transfer tube 2 Metal tube 3 Inner peripheral surface of metal tube 2 4,6,32 Fin 5 Outer peripheral surface of metal tube 2 7,8,33,42,52 Groove 9 No groove portion 13,14 Grooved roll O Central axis of metal tubes 1, _31, 41 W ₇ , W ₈ , W ₃₃ Width of grooves ₇ , ₈ , ₃₃ T Plate material F _{1 One} surface of plate material T (outer periphery of metal tube 2 The surface that becomes the surface 5) The other surface of the F ₂ plate material T (the surface that becomes the inner peripheral surface 3 of the metal tube 2)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikatsu Arayama 128-7 Ogimachi, Aizuwakamatsu, Fukushima Prefecture 7-8 Mitsubishi Shindoh Co., Ltd. Wakamatsu Manufacturing (72) Inventor Kotaro Nagahara 128-7, Ogimachi, Aizuwakamatsu, Fukushima Prefecture Mitsubishi Shin Copper Wakamatsu Manufacturing Co., Ltd. (72) Inventor ▲ Sukumo ▼ Shun Tad ▲ Green ▼ 128-7 Ogimachi, Aizuwakamatsu City, Fukushima Prefecture Mitsubishi Shindoh Co., Ltd. Wakamatsu Manufacturing Co., Ltd.

Claims (5)

[Claims] 1. A grooved heat transfer tube, wherein a large number of grooves extending in the axial direction of the metal tube are formed on the inner peripheral surface and the outer peripheral surface of the metal tube. 2. The metal pipe is provided with a grooveless portion in which the groove is not formed along the axial direction, and
The heat transfer tube with groove according to claim 1, wherein the groove is formed in a direction intersecting with the grooveless portion. 3. The groove formed on at least the outer peripheral surface of the metal pipe is formed so that the groove width becomes gradually smaller toward the outer peripheral side. Heat transfer tube with groove described in. 4. The groove formed on the inner peripheral surface of the metal tube and the groove formed on the outer peripheral surface are formed in a spiral shape extending in opposite directions around the axis. The heat transfer tube with a groove according to any one of claims 1 to 3. 5. A plate strip made of metal is formed with a large number of grooves extending in the longitudinal direction of the plate strip, and then the strip is set so that the one surface faces outward. A method for producing a grooved heat transfer tube, which comprises rolling a material in its width direction so that both side edges of the sheet material are opposed to each other, and then the both side edges are butted and joined to form a tubular shape.