JP2002005588A - Inner helically grooved tube and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner helically grooved tube in which pressure loss can be reduced advantageously and condensation effect can be enhanced effectively. SOLUTION: In the inner surface of a tube, a large number of first grooves 12 are made to extend helically in the tube axis direction at a helix angle of 10-30 deg. with respect to the tube axis, and 1-6 second grooves 14 extending in the tube axis direction are made per one round while intersecting the first grooves 12 with a groove width 1.3-8 times as large as the pitch of the first grooves 12 in the circumferential direction of tube.

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 having an inner surface groove suitably used for an air conditioner or a refrigeration device, and a method for manufacturing the same. The present invention relates to a grooved heat transfer tube and a method by which it can be advantageously manufactured.

[0002]

2. Description of the Related Art Conventionally, as one type of heat transfer tube incorporated in a heat exchanger such as an evaporator or a condenser in an air conditioner or a refrigeration device represented by an air conditioner or the like, a large number of grooves are formed on the inner surface of the tube. A so-called internally grooved heat transfer tube formed so as to extend continuously in a spiral shape in a direction is known. In recent years, in such a heat transfer tube with an inner surface groove, heat transfer by optimizing the depth, width, the number of leads, the lead angle, or the height, thickness, apex angle, etc. of fins formed between the spiral grooves. To improve the heat exchange efficiency of the heat exchanger into which the heat exchanger is incorporated.
In various publications including 2483 publication, etc.,
Various proposals have been made regarding the optimal design of the spiral grooves and fins. However, there is a limit to improving the heat transfer performance of the internally grooved heat transfer tube by merely changing the design of the spiral groove and the fin, and it is difficult to further improve the performance of the internally grooved heat transfer tube. It was.

[0003] Under such circumstances, JP-A-3-234302 and JP-A-8-303905 disclose,
Disclosed are internally grooved heat transfer tubes each having a plurality of main grooves spirally extending in the tube axis direction and a number of sub-grooves extending crossing the plurality of main grooves.

[0004] That is, in the former publication, the sub-groove is formed so that a large number of tubular portions having the opening width of the main groove intermittently narrowed are formed at predetermined intervals in the longitudinal direction of the main groove. An inner grooved heat transfer tube provided intersecting the main groove is disclosed, and in such a case, when such an inner grooved heat transfer tube is used as an evaporator tube in an evaporator, the heat transfer tube is formed in a tubular portion. It is described that bubbles serving as boiling nuclei are easily generated and evaporation is promoted, whereby the vaporization efficiency of the heat transfer medium can be increased. Also, the latter publication discloses an inner grooved heat transfer tube in which a main groove is formed so as to be shifted (offset) in the tube axis direction with an intersecting portion with a sub groove interposed therebetween. When such a heat transfer tube with an inner groove is used as a condensation tube in a condenser, the heat transfer medium is formed by a heat transfer medium that has condensed into a liquid and a heat transfer medium that has not yet condensed and remains in a gaseous state. It is described that the concentration boundary layer can be reliably renewed at the intersection of the main groove and the sub-groove, thereby reducing the diffusion resistance of the concentration and thereby exhibiting a high condensation performance.

However, according to the study of the present inventors, among the two types of heat transfer tubes with internal grooves disclosed in the above two publications, the heat transfer tubes with internal groove disclosed in Japanese Patent Application Laid-Open No. 3-234302 are disclosed. In this method, it is difficult to obtain better condensation performance than a conventional heat transfer tube with an inner surface groove in which only a plurality of spiral grooves are formed on the inner surface of the tube, and Japanese Patent Application Laid-Open No. 8-303905.
In the heat transfer tube with an inner surface groove disclosed in Japanese Patent Laid-Open Publication No. H11-107, the turbulent flow promoting effect at the intersection of the main groove and the sub-groove is further enhanced, so that the flow resistance of the heat transfer medium in the tube is reduced. It has been found that the pressure loss is inevitably increased in comparison with a conventional heat transfer tube with internal grooves having only a large number of spiral grooves.

[0006]

Here, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide only a spiral groove extending spirally in a pipe axis direction on a pipe inner surface. It is an object of the present invention to provide a heat transfer tube with internal grooves in which the pressure loss can be advantageously reduced and the condensation performance can be effectively increased, as compared with conventional heat transfer tubes with internal grooves in which a large number of are formed. Another object of the present invention is to provide a method for advantageously producing such a heat transfer tube with an inner groove.

[0007]

According to the present invention, in order to solve the above-mentioned problem, a large number of first grooves are formed on the inner surface of a pipe and extend continuously in a spiral manner toward the pipe axis direction. An inner grooved heat transfer tube in which a second groove extending continuously in the tube axis direction is formed while intersecting with the first groove,
The first groove is formed with a twist angle of 10 to 30 ° with respect to the tube axis, while the second groove is formed with a twist angle of 20 ° or less with respect to the tube axis. An inner grooved heat transfer tube, wherein 1 to 6 grooves are formed per circumference with a groove width of 1.3 to 8 times the pitch of the first groove in the pipe circumferential direction, This is the gist.

[0008] In such a heat transfer tube with an inner surface groove according to the present invention, the second groove is formed to intersect the first groove extending helically in the tube axis direction. However, the condensate of the heat transfer medium caused to flow along the first groove and the condensate of the heat transfer medium flowing along the second groove are formed by the first groove and the second groove. Impacted at the intersection, the smooth flow of condensate of the heat transfer medium along the first groove is disturbed, whereby
Turbulence can be appropriately promoted at the intersection of the first groove and the second groove.

Further, in such a heat transfer tube with internal grooves,
The second groove has a small torsion angle parallel to or close to the tube axis, and has a pitch in the circumferential direction of the first groove, more specifically, a first pitch defined by the pitch. Since the groove is configured to have a sufficiently large groove width compared to the width of one groove, the second groove sufficiently plays a role as a drain groove for condensed liquid of the heat transfer medium. , Whereby the condensate can be efficiently displaced along the second groove, so that the fins formed between the first grooves are effective for condensing heat transfer. Submersion of the tip into the condensate can be advantageously eliminated or suppressed, and such a second groove has a large groove width, but is formed in a very small number, The formation of the second groove reduces the effective heat transfer area in the tube. DOO is as it can be prevented as much as possible.

Further, in the heat transfer tube with an inner surface groove according to the present invention, as described above, the heat transfer medium can be efficiently removed along the second groove having a sufficiently large groove width. Therefore, such a heat transfer medium can be caused to flow more smoothly in the pipe, and thereby, the flow resistance of the heat transfer medium in the pipe can be advantageously reduced.

Therefore, in the heat transfer tube with an inner groove according to the present invention, a conventional heat transfer tube with an inner groove having a large number of spiral grooves extending spirally in the tube axis direction is formed on the inner surface of the tube. In comparison, the pressure loss can be advantageously reduced and the condensation performance can be effectively increased.

[0012] In the heat transfer tube with an inner groove according to the present invention, the second groove preferably has a depth of 0.5 to 1.2 times the depth of the first groove. It will be formed with a certain height. According to such a configuration, more condensate of the heat transfer medium is caused to flow along the second groove, whereby the second groove is configured to drain the condensate of the heat transfer medium. Not only does it more fully serve as a groove, but also due to the collision of the condensate of the heat transfer medium flowing along the first groove with the condensate of the heat transfer medium flowing along the second groove. The disturbing effect can be more advantageously enhanced, and the improvement of the condensation performance can be enhanced even more effectively.

According to the present invention, there is provided a method for manufacturing an inner grooved heat transfer tube having the above-described structure, wherein a raw tube for providing the inner grooved heat transfer tube is prepared while an outer circumferential surface is provided. A first plug having a large number of first ridges extending in the axial direction with a shape corresponding to the first groove;
A second plug formed on the outer peripheral surface and having a second ridge extending in the axial direction with a shape corresponding to the second groove, in the longitudinal direction in the inner hole of the raw tube; Are arranged in series along the same axis so as to be rotatable about the central axis of the tube, and further, at positions corresponding to the positions of the first and second plugs around the tube. Arranging a first compaction member and a second compaction member, and moving the raw tube continuously from the first plug side toward the second plug side, In a state where the plug is rotated around the central axis of the tube, the first plug is pressed against the outer surface of the tube by the first rolling member, so that the inner surface of the tube is A plurality of the first grooves are formed by the first ridges of the first plug, and among the plurality of first grooves, After forming ridges extending in the pipe axis direction of the raw pipe along the first groove between the pipes adjacent to each other in the circumferential direction, the second plug is connected to the central axis of the raw pipe. By rotating the base tube against the second plug from the tube outer surface with the second rolling member in a state of being rotated around, the plurality of first grooves on the inner surface of the base tube Of the ridges formed between them, those that come into contact with the distal end surface of the second ridge of the second plug with the movement of the raw tube are sequentially bent or crushed and deformed. The gist of the present invention is also a method of manufacturing a heat transfer tube with an inner surface groove, wherein the second groove is formed.

According to the method for manufacturing a heat transfer tube with an inner surface groove according to the present invention, the first groove and the second groove can be formed at once at the inner surface of one continuous raw tube. Thus, the intended heat transfer tube with an inner groove can be produced very quickly and at a lower cost, and very advantageously.

Furthermore, the present invention also provides a method of manufacturing an inner grooved heat transfer tube having the above-mentioned structure, wherein a strip-shaped material for providing the inner grooved heat transfer tube is prepared. An outer peripheral surface, a first roll provided with a large number of first ridges extending in the circumferential direction with a shape corresponding to the first groove, and an outer peripheral surface having a shape corresponding to the second groove. A second roll formed with a second ridge extending in the circumferential direction can be rotated on one surface of the strip-shaped material in series along its length direction and each around one axis. Arranged while continuously moving the strip-shaped material from the first roll side toward the second roll side,
By pressing the first roll against one surface of the strip-shaped material in a state where the first roll is rotated about its axis, the first roll of the first roll is moved against the one surface. Along with forming a large number of the first grooves in the ridge,
After forming a ridge extending along the first groove between those adjacent to each other in the length direction of the strip-shaped material among the many first grooves, the second roll is removed. By pressing against one surface of the strip material in a state where it is rotated around its axis, among the ridges formed between the plurality of first grooves on the one surface, What is in contact with the end face of the second ridge of the second roll with the movement of the strip-shaped material is sequentially bent or crushed and deformed to form the second groove. Further, thereafter, there is also provided a method for manufacturing a heat transfer tube having an inner surface groove, wherein the surface in which the first and second grooves are formed is turned inside, and the strip-shaped material is formed. , Its gist.

According to the method of manufacturing a heat transfer tube with inner grooves according to the present invention, a series of steps including a groove forming step and a pipe forming step is performed on one strip-shaped material. The intended heat transfer tube with an inner groove can be manufactured at once from the single strip-shaped material and efficiently.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to clarify the present invention more specifically, a specific configuration of a heat transfer tube with an inner surface groove according to the present invention and a manufacturing method thereof will be described in detail with reference to the drawings. It will be explained.

First, FIG. 1 shows an example of an inner grooved heat transfer tube having a structure according to the present invention in an end view in a cross-sectional form cut in a direction perpendicular to the tube axis direction. 2 shows an enlarged view of a main part of FIG. 1, and FIG. 3 shows a state in which such a heat transfer tube with an inner surface groove is cut parallel to the tube axis direction and developed. .
FIG. 3 shows the two types of grooves for easy understanding of the inclination form of the first and second grooves with respect to the pipe axis.
In particular, the first groove is shown exaggerated, for which,
It should be understood that in the developed view of FIG. 3, such a first groove is shown with a smaller number of arrangement lines as compared with FIG.

As is apparent from FIGS. 1 to 3, the heat transfer tube 10 with an inner groove has a hollow straight tube shape having a circular cross section as a whole. The inner grooved heat transfer tube 10 is employed as an evaporator tube, a condenser tube, or a heat pipe main body.
In order to form a flow path for a heat transfer medium such as a refrigerant inside the tube, in addition to a circular shape, a hollow tube structure having an appropriate cross-sectional shape such as an elliptical shape or a flat oblong shape is used. is there. In the inner grooved heat transfer tube 10, an appropriate material such as copper, a copper alloy, or an aluminum alloy is used as a constituent material in accordance with the required heat transfer performance, the type of the heat transfer medium to be used, and the like. A metal material will be used appropriately.

Further, in the heat transfer tube 10 having the inner groove, the outer peripheral surface is smooth, while the inner peripheral surface has
A large number of first grooves 12 and a plurality of second grooves 14 are formed.

More specifically, the number of first grooves 12 is
In the cross section perpendicular to the tube axis, each has a substantially trapezoidal shape gradually narrowing toward the bottom, and is inclined with respect to the tube axis to form a spiral in the tube axis direction. It is provided with a form extending continuously.
Further, 32 first grooves 12 are provided on an end surface of a cross section perpendicular to the pipe axis. That is, the first groove 12 is formed on the inner surface of the inner grooved heat transfer tube 10 in 32 rows per circumference. And by providing such a large number of first grooves 12, between the first grooves 12 adjacent to each other in the pipe circumferential direction on the inner surface of the pipe, the fins 16 having a ridge form are respectively formed. It is formed one by one. Moreover, those fins 16
Each has a tube axis perpendicular cross-sectional shape corresponding to the shape of each first groove 12 and gradually becoming narrower toward the tip, and exhibiting a substantially trapezoidal shape having a flat tip surface, Along each of the first grooves 12, it is formed in such a manner as to be inclined with respect to the tube axis and to extend helically continuously in the tube axis direction.

On the other hand, the plurality of second grooves 14 also have a substantially trapezoidal shape having a width gradually narrowing toward the bottom in a cross section perpendicular to the tube axis, and are inclined with respect to the tube axis. Although it is formed so as to extend continuously spirally toward the pipe axis direction, the width of the bottom is sufficiently larger than the width of the bottom of each of the first grooves 12. In addition, the size of the inclination angle with respect to the tube axis (the twist angle with respect to the tube axis = lead angle) is sufficiently smaller than that of the first groove 12. Further, four second grooves 14 are provided on the end face of the cross section perpendicular to the pipe axis, that is, four grooves are provided per circumference.

That is, the heat transfer tube 1 with an inner groove according to the present embodiment.
At 0, a large number of first grooves 12 and a large number of fins 16 having a narrow groove width are alternately arranged in the pipe circumferential direction on the pipe inner surface, and extend continuously in the pipe axial direction in a spiral form. And a plurality of second grooves 14 having a wide groove width are formed so as to extend continuously in a spiral manner toward the tube axis direction while intersecting with the first grooves 12. It is configured as a heat transfer tube with an internal spiral groove having a heat transfer area efficiently increased in a limited space of the tube inner surface.

Incidentally, in such a heat transfer tube 10 with an inner surface groove, the sectional shape of each of the first groove 12 and the second groove 14 is not particularly limited. The type of the heat transfer medium to be performed, the mass velocity of the heat transfer medium flowing through the pipe, and the like are appropriately determined. For example, in addition to the trapezoidal shape as described above, a V-shaped A shape such as a shape, a U-shape, or an arc shape forming a part of a circle such as a perfect circle, an ellipse, or an ellipse can be adopted. The cross-sectional shape of the fin 16 is
It goes without saying that the first groove 12 can be variously deformed in accordance with the cross-sectional shape.

As described above, in the heat transfer tube 10 having the inner groove, although the shapes of the first and second grooves 12, 14 can be freely set, the first and second grooves 12, 1 are not limited.
The torsion angle (lead angle) with respect to the tube axis of No. 4 needs to be in a specific value range. In particular, the torsion angle (lead angle) of the first groove 12 with respect to the tube axis: α is 10 to 30. °
It must be. If the twist angle α of the first groove 12 with respect to the tube axis is less than 10 °, the space between the first grooves 12 is reduced when the heat transfer tube 10 with the inner surface groove is used as a condensation tube. The shearing force of the heat transfer medium due to the vaporized gas at the tip of the fin 16 formed at the bottom is reduced, and the effect of thinning the condensate of the heat transfer medium is reduced. As a result, the heat transfer coefficient is sharply reduced. It is because it will be. When the torsion angle α of the first groove 12 with respect to the tube axis is larger than 30 °, the lead angle α is too large, and the workability of the first groove 12 with respect to the inner surface of the tube is significantly deteriorated. Therefore, it is difficult to form a large number of the first grooves 12 on the inner surface of the pipe, and further, in terms of performance, the increase in pressure loss becomes remarkable, and this becomes an evaporating pipe. This is because it has a bad influence on the heat transfer performance when used. The torsion angle of the first groove 12 with respect to the tube axis: α
In order to achieve higher heat transfer performance while ensuring excellent workability on the inner surface of the pipe, it is more preferable that the angle be about 15 to 25 °.

The torsion angle (lead angle) β of the second groove 14 with respect to the tube axis must be 20 ° or less. If the twist angle β of the second groove 14 with respect to the pipe axis is larger than 20 °, the second groove 14
This is because the smooth flow of the heat transfer medium caused to flow along the heat transfer medium is hindered, and the flow resistance of the heat transfer medium in the pipe increases, thereby increasing the pressure loss. Therefore, in the heat transfer tube 10 with the inner surface groove according to the present embodiment, the smaller the torsion angle β of the second groove 14 with respect to the tube axis, that is, the more the second groove 14 moves with respect to the tube axis. The closer to parallel, the lower the pressure loss can be,
In particular, when used as an evaporating tube, excellent evaporating performance can be exhibited. In that sense, the twist angle β of the second groove 14 with respect to the tube axis is set to 5 ° or less. Is more desirable.

In such a heat transfer tube 10 with an inner groove, the width W of the second groove 14 is 1.3 to 8 with respect to the pitch P of the first groove 12 in the circumferential direction of the tube. It must be set to an extremely large size as compared with the sub-groove in the conventional inner grooved heat transfer tube with cross grooves as described above. If the ratio is smaller than 1.3 times, the second groove 1
Width of 4: W becomes too narrow, so that the condensate of the heat transfer medium is less likely to be removed along the second groove 14, whereby
Not only is the fin formed between the first grooves 12 submerged in the condensate at the fin tip which effectively acts on the heat transfer of condensation, so that the improvement of the condensation performance cannot be expected. , The second grooves 14 are formed more than necessary, and the turbulence promoting effect at the intersection of these many second grooves 14 and the many first grooves 12 is increased more than necessary. Thereby, the flow resistance of the heat transfer medium in the pipe is significantly increased, and the pressure loss is inevitably increased. Also, the second groove 14
Is the pitch of the first groove 12 in the pipe circumferential direction:
In the case where the dimension is larger than 8 times P, the groove width: W is too large, and the workability of the second groove 14 at the time of processing the inner surface of the pipe is significantly reduced. Second groove 1
4 and the number of the first grooves 12 are reduced, so that the effective heat transfer area is extremely reduced, whereby the first and second grooves 12,
This is because the effect of promoting heat transfer due to the formation of No. 14 cannot be expected.

That is, the width W of the second groove 14 formed on the inner surface of the heat transfer tube 10 with an inner surface groove is determined by the first value in order to improve the condensation performance of the heat transfer tube 10 and reduce the pressure loss. The pitch of the groove 12 in the circumferential direction of the pipe 12 is set within the range of the ratio as described above, but in order to obtain such characteristics more effectively, the second groove 14 is required. Is more preferably about 2 to 5 times. Further, the heat transfer tube 10 with an inner groove is provided.
When used as a general condenser tube or evaporator tube, in practice, the first groove 12 has a pitch of about 0.15 to 0.85 mm, so the width of the second groove 14 is W: Is usually
It is set to a value within a range of about 0.5 to 2.0 mm.

Further, as described above, the heat transfer tube 10 with the inner surface groove is provided.
Since the second groove 14 is formed to have a sufficiently large width with respect to the first groove 12, the number of arrangement grooves of the second groove 14 is 1 to 6 per rotation. Within the limits of the article, it is necessary to make it sufficiently small. That is, the second groove 14 is
When formed with more than the number of lines, the width of the second groove 14:
Since it is difficult to secure an effective heat transfer area in a portion where the first groove 12 is formed on the inner surface of the tube while maintaining W within the above range, it is difficult to secure W.
It is necessary to set the number of arrangements of the second groove 14 within the above range. In addition, in the heat transfer tube 10 having the inner groove, the width of the second groove 14 and the effective heat transfer area on the inner surface of the tube are both sufficiently ensured to further improve the condensation performance and reduce the pressure loss. In order to effectively achieve this, it is preferable that the number of the arrangement grooves of the second groove 14 be,
It will be 2 to 4 articles per lap. On the other hand, the number of provided grooves of the first groove 12 is not particularly limited. The number of the provided grooves is excessively large, which causes a reduction in workability. The distance is appropriately set according to the groove pitch and the like so as not to reduce the area.

[0030] Note that such the inner surface grooved heat transfer tube 10 of the first groove 12 depth: D ₁ and the depth of the second groove 14:
D _2, although necessarily not intended to be a specific value, preferably, the depth of the second groove 14: D ₂ is a first groove 12 depth: 0.5 with respect to D ₁ The size is about 1.2 times. Because, the depth of the second groove 14: D
_{If 2} is less than 0.5 times the depth of the first groove 12: D ₁ , the flow rate of the heat transfer medium flowing along the second groove 14 is small. Too much
Not only does the second groove 14 not effectively function as a drainage groove for the condensate of the heat transfer medium, but also the condensate of the heat transfer medium flowed along the second groove 14 and the first groove This is because the effect of disturbing the heat transfer medium flowing along the flow path 12 with the condensed liquid is reduced, and as a result, expected condensation performance cannot be obtained. The depth of the second groove 14: D ₂ is the depth of the first groove 12 than D ₁ 1.2
If it is larger than twice, the second groove 14 becomes too deep, and the workability of the second groove 14 deteriorates.
This is because the pressure resistance of the inner grooved heat transfer tube 10 is significantly reduced.

As described above, in the heat transfer tube 10 with an inner surface groove according to the present embodiment, the first surface extending on the inner surface of the heat transfer tube with a predetermined twist angle with respect to the tube axis in a helical manner in the tube axis direction. A large number of grooves 12 are formed, and a second groove 14 having a sufficiently large groove width than the first groove 12 has a relatively small twist angle with respect to the tube axis. While intersecting with each other, the spiral groove continuously extends spirally in the pipe axis direction, and is formed in a small number of rows. The pressure loss can be advantageously reduced and the condensing performance can be effectively increased as compared with the conventional heat transfer tubes having a large number of inner grooves formed therein.

By the way, the heat transfer tube 10 with inner grooves exhibiting such excellent characteristics is manufactured by using, for example, a known rolling method or rolling method.

That is, in the case of manufacturing the heat transfer tube 10 with the inner surface groove by utilizing the rolling process, for example, one continuous rolling device 18 having a structure as shown in FIG. 4 is used. By subjecting the raw tube 20 to a predetermined rolling process, the intended inner surface grooved heat transfer tube 10 is obtained.

Specifically, in the rolling apparatus 18 used here, the raw tube 20 for providing the target heat transfer tube 10 with the inner surface groove is formed in the same direction as the conventional one in the tube axial direction (in the drawing). ,
(In the direction of the arrow). Around the base tube 20, a first circular die 22, a first rolling member 24, a second rolling member 26, and a second circular die 28 are respectively provided on adjacent ones. The tubes 20 are sequentially arranged from the upstream side to the downstream side in the moving direction of the raw tubes 20 with a space therebetween. Further, each of them has a ring shape having an inner hole having a diameter smaller than the outer diameter of the raw tube 20 by a predetermined dimension, and further, the inner diameter is gradually reduced in accordance with the arrangement order. It is configured.

On the other hand, a floating plug 32, a first grooved plug 34, and a second grooved plug 36, which are connected to each other by a tie rod 30,
Are located at positions corresponding to the first circular die 22, the first compaction member 24, and the second compaction member 26 disposed around the raw tube 20, respectively, in a rotatable state around the tube axis. , And are arranged coaxially. Of these three plugs, the floating plug 32 has the same structure as the conventional one, and the downstream part in the moving direction of the raw tube 20 is:
It has a stepped cylindrical block shape that is smaller in diameter than its upstream part.

As shown in FIG. 5, the first grooved plug 34 has a plurality of first groove forming ridges 3 on its outer peripheral surface.
8 is formed so as to extend continuously in the axial direction while being inclined with respect to the axial center. The first groove-forming ridge 38 has a cross-sectional shape perpendicular to the axis of the first grooved plug 34, which is to be formed on the inner surface of the target inner surface grooved heat transfer tube 10. The groove 12 has a shape corresponding to the cross-sectional shape perpendicular to the tube axis, and the magnitude of the torsion angle with respect to the axis is the same as the torsion angle of the first groove 12 with respect to the tube axis of the heat transfer tube 10 having the inner groove. It has a corresponding size.

On the other hand, as shown in FIG. 6, the second grooved plug 36 also has a second groove forming ridge 40 on its outer peripheral surface.
The same number as the number of the second grooves 14 to be formed on the inner surface of the target inner surface grooved heat transfer tube 10 is formed so as to extend continuously in the axial direction while being inclined with respect to the axis. Have been. The second groove forming ridge 40 has a cross-sectional shape perpendicular to the axis of the second grooved plug 36, and a cross-section perpendicular to the tube axis of the second groove 14 in the inner grooved heat transfer tube 10. In addition to the shape corresponding to the shape, the magnitude of the torsion angle with respect to the axis is set to the magnitude corresponding to the torsion angle of the second groove 14 with respect to the tube axis of the heat transfer tube 10 having the inner groove.

In order to actually manufacture the intended heat transfer tube 10 having an inner surface groove by using the rolling device 18 having such a structure, first, the raw tube 20 is shown in FIG. The diameter is reduced between the floating plug 32 and the first circular die 22 by pulling and moving in the direction of the arrow. Next, the raw tube 20 is pressed against the first grooved plug 34 from the outer surface of the tube by the first rolling member 24,
Further, the diameter of the first grooved plug 34 is reduced by a predetermined dimension, and the first grooved plug 34 is rotated around the pipe axis of the raw tube 20.
Are successively depressed at the portions contacting the distal end surface of the first groove forming ridge 38. As a result, the first groove 1 recessed in the inner surface of the base tube 20 with a shape and a twist angle corresponding to the first groove forming ridge 38 of the first grooved plug 34.
2 are continuously formed spirally toward the pipe axis direction, and a large number of them are formed. At the same time, a ridge form is formed between the first grooves 12 adjacent to each other in the pipe circumferential direction. One fin 16 is formed along the first groove 12.

Next, the raw tube 20 in which a large number of the first grooves 12 and the fins 16 are respectively formed is connected to the second grooved plug 3.
6 is pressed from the outer surface of the tube by the second rolling member 26 to further reduce the diameter.
Is rotated around the tube axis of the raw tube 20 to form a large number of fins 1.
6, the second grooved plug 3
Those that come into contact with the front end surface of the second groove forming ridge 40 in 6 are sequentially bent or crushed and deformed by the ridge 40. As a result, the second groove 14 recessed with a shape and a torsion angle corresponding to the groove forming ridge 40 of the second grooved plug 36 crosses the first groove 12 in the tube axis direction. A plurality is formed so as to extend continuously in a spiral shape. At this time, some of the fins 16 may not be sufficiently deformed, but the effect as described above achieved by forming the second groove 14 is not hindered by such fins 16. .

Thereafter, the base tube 20 is cut to a predetermined length as required, and thus continuously extends spirally in the tube axis direction on the inner surface of the tube at a predetermined twist angle with respect to the tube axis. A large number of first grooves 12 are formed, and the first grooves 12
A second groove 14 having a groove width sufficiently larger than that of the first groove 12 intersects the first grooves 12 at a relatively small twist angle with respect to the tube axis, and continuously spirals in the tube axis direction. Formed with a small number of strips,
The inner grooved heat transfer tube 10 as shown in FIGS. 1 to 3 is continuously manufactured.

As described above, according to the method using the rolling device 18 as shown in FIG. 4, the continuous single pipe 20 is formed by the first and second grooved plugs 34 and 36. Since the first and second grooves 12 and 14 can be formed at once in the inner surface, the intended heat transfer tube 10 with the inner surface groove can be manufactured very quickly and at a lower cost, and very advantageously. is there.

In the case of manufacturing the heat transfer tube with inner grooves 10 using the rolling method, for example, a continuous strip-shaped plate is formed by using a processing device 42 having a structure as shown in FIG. While moving the material 44 in the longitudinal direction, the band-shaped material 4
By subjecting 4 to groove processing or tube forming by a predetermined rolling process, the intended inner surface grooved heat transfer tube 10 is obtained.

More specifically, the processing device 42 used here is driven by a driving roll (not shown) by a strip-shaped material 44.
Can be moved to one side in the length direction (the direction indicated by the arrow in FIG. 7). Then, at the most upstream side in the moving direction of the band-shaped material 44, guide rolls 46 sandwiching the band-shaped material 44 up and down,
46 are arranged, and guided by the guide rolls 46, 46, the first and second two strips 44 are arranged at predetermined intervals on the upstream side and the downstream side in the movement direction. The rolls are guided to rolling rolls 48 and 50.

As shown in FIG. 8, of the two rolling rolls 48 and 50, the first rolling roll 48 located on the upstream side in the moving direction of the strip material 44 has a large number on its outer peripheral surface. Is formed so as to extend continuously in the circumferential direction while being inclined with respect to the axis perpendicular to the axis. The first groove forming ridge 52 has a cross-sectional shape parallel to the axis of the first rolling roll 48 so that the first groove 12 to be formed on the inner surface of the target inner grooved heat transfer tube 10 is formed.
And the magnitude of the torsion angle with respect to the axis perpendicular to the axis is the first groove 12 with respect to the axis of the heat transfer tube 10 having the inner groove.
It has a size corresponding to the torsion angle.

On the other hand, as shown in FIG.
The second rolling roll 50 disposed downstream of the moving direction of the fourth roll 50
In the outer peripheral surface, the second groove forming ridge 54 is continuously extended in the circumferential direction while being inclined with respect to the axis perpendicular to the axis, so that the inner surface of the target inner grooved heat transfer tube 10 is formed. As many as the number of the second grooves 14 to be formed are formed. In addition, the second groove forming ridges 54 are formed on the second rolling roll 5.
The cross-sectional shape parallel to the center axis of the inner grooved heat transfer tube 10
And the size of the torsion angle with respect to the axis perpendicular to the axis of the second groove 14 relative to the axis of the inner grooved heat transfer tube 10 with respect to the axis of the tube. The size corresponds to the twist angle of the second groove 14.

As shown in FIG. 7, the first rolling roll 48 and the second rolling roll 50 are provided on one surface of the strip-shaped raw material 44 with supporting rolls disposed below each other. The belt-shaped material 44 is sandwiched between the members 56 and 56 and is pressed by a predetermined pressure so as to be rotatable around one axis.

Further, on the downstream side of the first and second rolling rolls 48 and 50 in the moving direction of the strip-shaped material 44, the same as the conventional one for gradually forming the strip-shaped material 44 into a tube. Pairs of forming rolls 58-74 having a simple structure
Are arranged so as to be rotatable around their respective axes in a state where the strip-shaped material 44 is sandwiched in the vertical direction by the rolls forming a pair, and the nine pairs of forming rolls 58 are further arranged. On the downstream side of ~ 74, like the conventional device,
A pair of seam guide rolls 76 for guiding the tubular sheet material 44 formed into a tubular shape by the nine pairs of forming rolls 58 to 74 further downstream, and a width direction of the tubular sheet material 44. A high-frequency induction coil 78 and a pair of squeeze rolls 80 are welded to each other at both ends to form one continuous tube.
Is arranged.

Then, in order to manufacture the target heat transfer tube 10 with the inner surface groove by using the rolling processing device 42 having the above-described structure, first, the strip-shaped raw material 44 is formed by a driving roll (not shown). , Is moved to one side in the length direction (in the direction of the arrow in FIG. 7), guided to the first rolling roll 48 side by the guide rolls 46, 46, and rotated around the axis by the movement of the strip-shaped material 44 At the first rolling roll 48 to be urged,
One surface of the strip-shaped material 44 is pressed, and on the one surface, the first groove-forming ridge 52 of the first rolling roll 48 is moved along with the movement of the strip-shaped material 44 so as to have a leading end surface. The contacting parts are sequentially depressed. As a result, the first groove 12 that is recessed on one surface of the strip-shaped material 44 with a shape and a twist angle corresponding to the first groove-forming ridge 52 of the first rolling roll 48 is formed. A plurality of fins are formed so as to extend continuously in the length direction of the material 44, and at the same time, between the first grooves 12 adjacent to each other in the width direction of the strip-shaped material 44. 16 are formed one by one along the first groove 12.

Next, the strip-shaped material 44 in which the first groove 12 and the fins 16 are formed in large numbers on one surface is moved to the second rolling roll 50 side. One surface of the strip-shaped material 44 is pressed by the second rolling roll 50 that is rotated around the center, and the strip-shaped material 44 of the many fins 16 formed on the one surface is pressed. In the second rolling roll 50, the one that comes into contact with the distal end surface of the second groove forming ridge 54 is sequentially bent or crushed and deformed by the ridge 54. Thereby, the second groove 1 recessed with a shape and a twist angle corresponding to the second groove forming ridge 54 of the second rolling roll 50.
4 while intersecting with the first groove 12,
4 so as to extend continuously in the length direction.

Thereafter, the belt-shaped material 44 is formed into a tubular shape with nine pairs of forming rolls 58 to 74 with the surfaces on which the first and second grooves 12 and 14 are formed inward. Strips 44 positioned opposite to each other by
Are welded by high-frequency induction with a high-frequency induction coil 78 and a pair of squeeze rolls 80 to form a single continuous pipe 82. Thus, on the inner surface of the pipe,
A large number of first grooves 12 and a plurality of second grooves 14 are formed to have a structure as shown in FIGS. 1 to 3 to obtain a target heat transfer tube 10 with an inner surface groove.

As described above, according to the method using the processing apparatus 42 as shown in FIG. 7, the first and second rolling rolls 48, 50 are
By performing a series of steps including a grooving process by using a pair of forming rollers and nine pairs of forming rolls 58 to 74 and a high-frequency induction coil 78, etc.
0 can be produced all at once and efficiently.

Incidentally, a plurality of types of heat transfer tubes with internal grooves having the structure according to the present invention were actually manufactured, and the above-described excellent characteristics of the plurality of types of heat transfer tubes with internal grooves were evaluated.

That is, first, a large number of the first grooves and a plurality of the second grooves are formed on the inner surface of the pipe in such a manner that they are spirally continuous in the pipe axis direction and extend to intersect with each other. Forming 10 kinds of heat transfer tubes with inner grooves (Examples 1 to 10) having the structure according to the present invention, which are configured with the dimensional specifications as shown in Table 1 below;
Got ready. Further, for comparison, a conventional heat transfer tube with a spiral groove on the inner surface (Comparative Example 1) in which only the first groove is provided on the inner surface of the tube, a first groove and a second groove (a main groove) And two types of heat transfer tubes with inner grooves (Comparative Example 2 and Comparative Example 3) in which the twist angle of the second groove with respect to the tube axis is outside the scope of the present invention. No. 28, in which a number of V-shaped grooves (first grooves) are formed.
A so-called heat transfer tube with inner pine flutes (Comparative Example 4) having a structure as shown in Japanese Patent No. 42810 or the like was formed and prepared with dimensional specifications as shown in Table 1 below.

The prepared 14 types of heat transfer tubes with inner grooves (Examples 1 to 10 and Comparative Examples 1 to 4) were all made of copper. In Table 1 below, the lead angle indicates the magnitude of the torsion angle of the first groove or the second groove with respect to the tube axis, and the number of threads is one of the first groove or the second groove.
It indicates the number of strips per circumference, that is, the number of the first grooves or the second grooves formed on the end face in a cross section perpendicular to the tube axis.
Further, the magnification in the column of the width of the second groove indicates a magnification of the width of the second groove with respect to the pitch of the first groove. The prepared 14 types of heat transfer tubes with inner grooves (Examples 1 to 10 and Comparative Examples 1 to 4) all had the first groove pitch of 0.37.
mm.

[0055]

[Table 1]

Next, the prepared 14 types of heat transfer tubes with inner grooves (Examples 1 to 10 and Comparative Examples 1 to 4), a conventionally known heat transfer performance test device, and R-41 as a refrigerant.
OA, various heat transfer tubes are assembled in a single tube with respect to the test section of the heat transfer performance test apparatus, and under the flow of a refrigerant as shown in FIG. 10, under the test conditions shown in Table 2 below, The condensation performance test was performed according to a known method, and the heat transfer coefficient and pressure loss in the tubes of the various heat transfer tubes were measured. And, among the measured values of the heat transfer coefficient and pressure loss in the tubes of each heat transfer tube obtained in this way, although they show superior condensation performance compared to general heat transfer tubes with internal spiral grooves, the pressure loss Of the heat transfer tube with inner crutches (Comparative Example 4), which is known to have a feature that the inner crimp size is extremely large, using the measured values of the heat transfer coefficient in the tube and the measured value of the pressure loss in the tube as reference (= 1.0), respectively. With the inner crutches of the measured values of the heat transfer coefficient in the pipe and the pressure loss in the pipe in 13 types of heat transfer pipes with inner grooves (Examples 1 to 10 and Comparative Examples 1 to 3) other than the heat transfer pipe with heat transfer (Comparative Example 4). The ratio of each of the measured values in the heat transfer tube (Comparative Example 4) was determined. The heat transfer coefficient ratio in the pipe of each inner grooved heat transfer tube (Examples 1 to 10 and Comparative Examples 1 to 3) based on the inner surface pine needle grooved heat transfer tube (Comparative Example 4) obtained from the result and the inside of the pipe FIG. 11 shows the relationship between the pressure loss ratios. The test section length in the condensation performance test was 4 m.

[0057]

[Table 2]

As is clear from the results shown in FIG. 11, in the ten types of heat transfer tubes with inner grooves having the structure according to the present invention (Examples 1 to 10), the torsion of the second groove with respect to the tube axis is obtained. Except for the inner grooved heat transfer tube having a relatively large angle (lead angle) (Example 6),
A conventional general internal spiral having a pressure loss ratio in a pipe based on a heat transfer tube with inner pine needle grooves (Comparative Example 4) of less than 0.9, and such a pressure loss ratio in a pipe exceeding 0.9. The value is clearly smaller than that of the grooved heat transfer tube (Comparative Example 1). Further, even in the heat transfer tube with an inner surface groove in which the torsion angle (lead angle) of the second groove with respect to the tube axis is relatively large (Example 6), the pressure loss ratio in the tube is lower than that of the conventional general inner surface. The value is substantially equal to that of the heat transfer tube with the spiral groove (Comparative Example 1), and does not exceed the value of the pressure loss ratio in the tube of the heat transfer tube with the internal spiral groove. Furthermore, although the first groove and the second groove are formed on the inner surface of the tube, the torsion angle (lead angle) of the second groove with respect to the tube axis is outside the scope of the present invention. Also for Comparative Examples 2 and 3, ten kinds of heat transfer tubes with inner grooves having the structure according to the present invention (Examples 1 to 1)
0) has a small in-pipe pressure drop ratio.

In the ten types of heat transfer tubes with internal grooves (Examples 1 to 10) having the structure according to the present invention, the heat transfer tubes with internal grooves (Example 7) having a relatively large number of second grooves are provided. )
Except for the above, the heat transfer coefficient ratio in the pipe based on the heat transfer tube with inner pine needle grooves (Comparative Example 4) exceeds 0.85, and the heat transfer coefficient ratio in the pipe is 0.85. The value is clearly larger than that of a conventional general heat transfer tube with internal spiral grooves (Comparative Example 1). Note that even in the heat transfer tube with an inner surface groove having a relatively large number of second grooves (Example 7), the heat transfer coefficient ratio in the tube is lower than that of a conventional general heat transfer tube with an inner spiral groove (comparative example). The value is substantially equivalent to 1), and does not fall below the value of the heat transfer coefficient ratio in the heat transfer tube with the internal spiral groove.

Although the specific configuration of the present invention has been described in detail above, this is merely an example, and the present invention is not limited by the above description, and the present invention is not limited thereto. The present invention can be implemented in an aspect in which various changes, modifications, improvements, and the like are made based on the knowledge of a trader. It goes without saying that all such embodiments are included in the scope of the present invention unless they depart from the gist of the present invention.

[0061]

As is apparent from the above description, in the heat transfer tube with an inner surface groove according to the present invention, a conventional structure in which only a large number of spiral grooves extending spirally in the axial direction of the tube are formed on the inner surface of the tube. The pressure loss can be advantageously reduced, and the condensation performance can be effectively increased, as compared with the heat transfer tube with an inner surface groove.

Further, according to the method of manufacturing a heat transfer tube with internal grooves using the rolling process according to the present invention, the first groove and the second groove are formed at once in the inner surface of one continuous raw tube. Therefore, the intended heat transfer tube with an inner surface groove can be manufactured very quickly and at a lower cost with great advantage.

Further, according to the method of manufacturing a heat transfer tube with internal grooves using the rolling method according to the present invention, a series of steps including a groove forming step and a pipe forming step for one strip-shaped material. By doing, the target heat transfer tube with inner groove,
It can be manufactured all at once and efficiently from the single strip-shaped material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional end view illustrating an example of a heat transfer tube with an inner groove according to the present invention.

FIG. 2 is a partially enlarged explanatory view of FIG.

FIG. 3 is a development view of the heat transfer tube with inner grooves shown in FIG. 1;

FIG. 4 is an explanatory view showing one example of a rolling apparatus for manufacturing the heat transfer tube with inner grooves according to the present invention.

FIG. 5 is an explanatory front view of a first grooved plug provided in the rolling apparatus shown in FIG. 4;

FIG. 6 is an explanatory front view of a second grooved plug provided in the rolling apparatus shown in FIG. 4;

FIG. 7 is an explanatory view showing an example of a processing apparatus for manufacturing a heat transfer tube with an inner groove according to the present invention.

8 is an explanatory front view of a first rolling roll provided in the processing apparatus shown in FIG. 7;

9 is an explanatory front view of a second rolling roll provided in the processing device shown in FIG. 7;

FIG. 10 is an explanatory diagram showing a refrigerant flowing state in a test device for measuring heat transfer performance during condensation of various heat transfer tubes as an example or a comparative example.

FIG. 11 is a graph showing the relationship between the heat transfer coefficient in the pipe and the pressure loss in each of the heat transfer pipes as examples and comparative examples.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 heat transfer tube with internal groove 12 first groove 14 second groove 20 raw tube 24 first pressure member 26 second pressure member 34 first grooved plug 36 second grooved plug 38 first Groove forming ridge 40 second groove forming ridge 44 strip-shaped material 48 first rolling roll 50 second rolling roll 52 first groove forming ridge 54 second groove forming ridge

Claims (4)

[Claims] 1. A plurality of first grooves spirally and continuously extending in a pipe axis direction are formed on an inner surface of a pipe, and intersect with the first grooves in the pipe axis direction. An inner grooved heat transfer tube having a continuously extending second groove formed therein, wherein the first groove is formed to have a twist angle of 10 to 30 ° with respect to the tube axis; The second groove has a torsion angle of 20 ° or less with respect to the pipe axis and a groove width of 1.3 to 8 times the pitch of the first groove in the circumferential direction of the pipe; A heat transfer tube with an inner surface groove, wherein one to six lines are formed. 2. The inner grooved transmission according to claim 1, wherein the second groove is formed to have a depth of 0.5 to 1.2 times the depth of the first groove. Heat tube. 3. The method for producing a heat transfer tube with an internal groove according to claim 1 or 2, wherein a raw tube for providing the heat transfer tube with an internal groove is prepared, while the outer peripheral surface is provided with the first heat transfer tube. A first plug having a large number of first ridges extending in the axial direction with a shape corresponding to the groove, and a second plug extending in the axial direction with a shape corresponding to the second groove on the outer peripheral surface. Coaxially with the second plug formed with the ridge in the inner hole of the raw tube in a state of being rotatable in series along the longitudinal direction thereof and around the central axis of the raw tube. And further, at a position corresponding to the position where the first and second plugs are arranged around the base tube, a first compaction member and a second compaction member are arranged, While the raw tube is continuously moved from the first plug side toward the second plug side, the first plug is While rotating around the central axis of the tube, by allowed to pressing at said first rolling member from outside the tube surface with respect to said first plug,
A plurality of the first grooves are formed on the inner surface of the tube by the first ridges of the first plug, and among the plurality of the first grooves, the first grooves are mutually connected in the circumferential direction of the tube. After forming ridges extending in the pipe axis direction of the raw pipe along the first groove between adjacent ones, the second plug was rotated around the central axis of the raw pipe. In this state, by pressing the raw tube against the second plug from the outer surface of the tube with the second rolling member, the raw material is formed between the plurality of first grooves on the inner surface of the raw tube. Among the crests, those which come into contact with the distal end surface of the second ridge of the second plug with the movement of the base tube are sequentially bent or crushed to deform the second plug. A method for manufacturing a heat transfer tube having an inner surface groove, wherein a groove is formed. 4. The method for producing a heat transfer tube with an inner groove according to claim 1 or 2, wherein a strip-shaped material for providing the heat transfer tube with an inner groove is prepared, A first roll provided with a large number of first ridges extending in the circumferential direction with a shape corresponding to the first groove, and a second roll extending in the circumferential direction with a shape corresponding to the second groove on the outer peripheral surface. And a second roll on which the ridges are formed are arranged on one surface of the strip-shaped material so as to be rotatable in series along the length direction thereof and around one axis, respectively. While moving the strip-shaped material continuously from the first roll side toward the second roll side, while rotating the first roll about its axis,
By pressing one surface of the strip-shaped material, a large number of the first grooves are formed on the one surface by the first ridges of the first roll. After forming a ridge extending along the first groove between those adjacent to each other in the longitudinal direction of the strip-shaped material among the first grooves, the second roll is By pressing against one surface of the strip material in a state of being rotated about the axis, among the ridges formed between the plurality of first grooves on the one surface, What comes into contact with the tip surface of the second ridge of the second roll with the movement of the strip-shaped material, sequentially bend or crush and deform,
The second groove is formed, and further, thereafter, the surface on which the first and second grooves are formed is turned inside, and the strip-shaped material is formed into an inner surface groove. Manufacturing method of heat transfer tubes