JP2000346580A - Heat transfer tube with inner surface groove, method and apparatus for manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transfer tube with an inner surface groove capable of not only improving reliability of a welded portion but also reducing a pressure loss and a method for manufacturing it. SOLUTION: A metal tube 10 has, on its inner periphery, one welded portion 16 extended in an axial direction of the tube, portions 20 each having no fin and formed in a strip-like state at both sides of the portion 16, and many fins 12 formed in a range except the portions 20 and the portion 16. One or above protruding strip-like portions 18 intersecting in a cross-like state with the fins 12 are formed at one ends of the fins 12 in such a manner that a height of the portion 18 is 10 to 120% of that of the fin 12.

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 with an inner groove having a fin formed on the inner surface of a metal tube to enhance the heat exchange efficiency, and a method and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art An inner grooved heat transfer tube of this type is mainly used as an evaporator tube or a condenser tube in a heat exchanger such as an air conditioner or a refrigerator, and recently has a spiral shape over the entire inner surface. Heat transfer tubes formed with such fins are widely commercially available.

[0003] A heat transfer tube, which is currently the mainstream, is formed by passing a floating plug having a spiral groove on the outer peripheral surface thereof through a seamless (seamless) tube obtained by drawing or extruding. Is manufactured by rolling spiral fins over the entire inner peripheral surface of the fin. However, this manufacturing method limits the shape and height of the fins due to the characteristics of the floating plug.
There are limits to improving the heat exchange efficiency by improving the fins.

[0004] The inventors of the present invention have proposed a "electrically welded pipe system" in which a long metal plate is rolled in the width direction and welded at both side edges of the metal plate to obtain a metal tube instead of a seamless tube. Used for heat tube production. This is because, according to the ERW pipe method, fins to be formed on the inner surface of the heat transfer pipe can be rolled in the state of a flat metal plate strip, and the fin shape has a high degree of design freedom.

FIG. 12 shows a state in which the fins 4 are rolled on the surface of the plate material 1 serving as the material of the heat transfer tube using the rolling rolls 2. The roll 2 is composed of a grooved roll 2A having a spiral groove formed on the outer peripheral surface, and a pair of grooveless rolls 2B fixed on both sides of the grooved roll 2A. A large number of fins 4 extending obliquely are rolled by a grooved roll 2 </ b> A in the center portion of the material 1, while a grooveless roll 2 is formed on both side edges of the plate material 1.
B forms a grooveless portion 1B having a constant width. The reason why the non-grooved portions 1B are formed on both side edges of the strip material 1 is that uniform welding is achieved by flattening both side edges of the strip material to be welded by butt welding during the electric resistance welding. This is to make it possible.

[0006]

However, in the conventional heat transfer tube with internal grooves, as the rolling of the fins 4 by the rolling rolls 2 progresses, the individual grooves 6 between the fins 4 are formed.
The material elongates downstream along the rolling direction. For this reason, as shown in FIG. 13, the side edge of the plate material 1 on the side opposite to the end of the individual fin 4 in the rolling direction is not straight, and the convex portion 8 is generated, and the side edge becomes wavy. A problem was found. When such deformation occurs, a gap may be formed between these butt surfaces when the non-grooved portions 1B are butt-welded in the electric resistance sewing process, and the quality of the welded portion may be uneven. Therefore, when the convex portion 8 is conspicuous, it was necessary to cut off the side edge and rework it in a straight line in order to enhance the reliability of the welded portion.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No. 7-27.
No. 1337 proposed an inner grooved heat transfer tube in which ridges were formed on both sides of a welded portion and a method of manufacturing the same. According to the method of manufacturing a heat transfer tube with an inner groove, a number of inclined fins and ridges extending in the longitudinal direction of the plate along both ends of the fins are simultaneously rolled on the plate before the electric resistance welding. By forming, there is an advantage that the material flow is prevented from being generated along the groove between the fins, and the occurrence of the convex portion can be reduced.

However, in the heat transfer tube with inner grooves according to the above-mentioned application, since relatively large ridges are formed on both sides of the welded portion, the swirling flow of the heat medium caused by the spiral fins causes these ridges. There is a strong tendency to be suppressed by the part, and there is room for improvement from the viewpoint of reducing the pressure loss of the heat medium flowing through the heat transfer tube with the inner groove.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a heat transfer tube with an inner groove which not only can improve the reliability of a welded portion but also can reduce a pressure loss, and a method for manufacturing the same.

[0010]

According to the present invention, there is provided a heat transfer tube with an inner groove, which has one welded portion extending in the axial direction of the metal tube on the inner peripheral surface of the metal tube and two welded portions on both sides of the welded portion. A finless portion formed in a belt shape, and in a range excluding the finless portion and the welded portion, a number of fins formed to be inclined with respect to a pipe axis, and at least one end of the fin has One or two or more ridges intersecting the fins in a cross shape are formed, and the height of the ridges is 10 to 120% of the height of the fins.

Further, in the method for manufacturing a heat transfer tube with an inner surface groove according to the present invention, a metal plate is passed through a pair of fin forming rolls while running the metal plate, whereby one surface of the plate is formed.
A strip-shaped finless portion along both side edges of the plate-like material, a large number of fins extending in a slanting direction with respect to the longitudinal direction of the plate-like material in a large number in a region interposed between these finless portions, A step of rolling at least one end portion and at least one or more ridge portions that are 10 to 120% of the height of the fins and cross each other in a cross shape, and a plate on which the ridge portions and the fins are formed. A pipe forming step of forming a tube through a plurality of forming rolls so that the ridges and fins are located on the inner peripheral side, and heating and butting both end edges of the plate-shaped plate formed into a tube And a welding step of welding.

Further, the apparatus for manufacturing a heat transfer tube with an inner surface groove according to the present invention is arranged such that a metal plate is passed through at least one pair of rolling rolls while running the metal plate, so that at least one surface of the plate is formed. A rolling mechanism for performing rolling, a tube forming mechanism for forming the rolled sheet material into a tubular shape through a plurality of forming rolls, and both end edges of the tubular shaped strip material. A welding mechanism for heating and butt-welding, and a belt-shaped finless portion along both side edges of the plate strip on the outer peripheral surface of the rolling roll facing one surface of the plate strip. A grooveless portion for forming
A large number of fin rolled grooves extending in a slanting manner with respect to the circumferential direction of the roll are arranged in a large number in a region sandwiched by these grooveless portions, and at least one or two or more crosswise crosses at least one end of the fin rolled grooves. A ridged rolling groove is formed.

[0013]

1 and 2 are a sectional view and an enlarged view of an inner surface of a heat transfer tube with an inner surface groove according to a tenth embodiment of the present invention. On the inner peripheral surface of the inner grooved heat transfer tube 10, one welded portion 16 extending in the tube direction, a band-shaped finless portion 20 adjacent to both sides of the welded portion 16, these finless portions 20 and A large number of fins 12 and grooves 14 are formed parallel to each other over the entire area excluding the welded portion 16. Further, on the one end 12B side of each fin 12, one ridge 18 that crosses each fin 12 in a cross shape is formed along the tube axis, which is a main feature of the present invention. Has become.

On the other hand, such a ridge 18 is not formed on the other end 12A of the fin 12. That is, the ridge 18 is formed only on one side of the welded portion 16, and the ridge 18 is not connected to the end of the fin 12 in a T-shape.
B is formed so as to protrude more toward the welded portion 16 than the ridge portion 18. In these respects, Japanese Patent Application No. 7-271337.
This is different from the invention according to the above item.

The one end portion 12B and the other end portion 12A are distinguished by which side the individual fins 12 are rolled from. For example, as shown in FIG. The other end 12A and the end on the side where the rolling of the fin 12 is completed are the one end 12B. At the other end 12A of the fin 12, the material extends toward the center of the plate material, whereas at the one end 12B, the material extends toward the outside of the plate material. On the side edge on the side, there is a tendency for more pronounced waveform deformation to occur than on the other end 12A side. By rolling the ridge 18 intersecting with the fin end 12B at the same time as the fin 12, the material flow is prevented at the position of the ridge 18, and the waving deformation can be effectively reduced.

The dimensions of the inner grooved heat transfer tube 10 are not limited in the present invention.
Its outer diameter is about 3 to 15 mm, and the thickness of the tube wall in the groove 14 is about 0.15 to 0.5 mm. The welded portion 16 generally protrudes from the inner peripheral surface of the inner grooved heat transfer tube 10, but may be completely removed if necessary.

The material of the inner grooved heat transfer tube 10 is not limited.
Various materials such as copper, copper alloy, aluminum, aluminum alloy, and steel can be used, but copper or copper alloy is preferably used. Among them, phosphorus deoxidized copper (for example, JIS1220 alloy), oxygen-free copper And the like are preferred.

As shown in FIG. 2, the fin 12 is formed so as to form a fixed angle α with respect to the tube axis, and has a spiral shape centered on the tube axis. The helical angle α is a value determined according to the characteristics required of the heat transfer tube 10 and is not limited in the present invention, but is preferably about 5 to 25 ° in a general heat transfer tube with an inner surface groove.

The height of the fins 12 is not limited, but is generally about 0.1 to 0.3 mm. The higher the fins 12 are, the greater the rolling reduction for forming the grooves 14 is, so that the waveform deformation at the side edges of the strip material tends to be remarkable, and the effect of the present invention is accordingly reduced. It will be easier to demonstrate. The shape of the fins 12 is not limited, and may be triangular in cross section (the tip may be rounded or pointed) as shown in FIG. 1, or may be trapezoidal or semicircular. May be.

The shape of both end portions 12A and 12B of the fin 12 is not limited, and may be a pointed shape as shown in the figure or a rounded shape. Also,
The height of the fins 12 may be gradually reduced toward the tips of both ends 12A and 12B, or may be constant. When the height of the fins 12 gradually decreases toward the tips of both ends 12A and 12B, the groove 1
The thickness of the tube wall in 4 may be gradually increased toward the weld 16.

The distance between both ends 12A, 12B of the fin 12 and the welded portion 16 is not limited, but as shown in FIG. 2, the center line of the welded portion 16 and each end 12A,
The distances W2 and W1 from the fin 12 are preferably about 20 to 160% of the pitch P of the fins 12 in the tube axis direction, and more preferably 60 to 120%. The reason why these values are determined based on the pitch P of the fins 12 depends on the angle of the fins 12, but the larger the pitch P, the more the waveform deformation of the end portion of the plate material tends to be severe.
This is because the effect of suppressing the waveform deformation by the ridges 18 increases as the distance W1 increases.

Distance W1 between one end 12B and center line of welded portion
May be larger than the distance W2 between the other end 12A and the center line of the welded portion. In this case, while the distance W1 can be kept large to further reduce the waveform deformation, the total length of the fins 12 can be increased by making the distance W2 as small as possible, and the heat exchange efficiency by the fins 12 can be promoted. Specifically, the distance W1 is 10 to 50% of the pitch P more than the distance W2.
Or about 0.05 to 0.3 mm. However, if the difference between the distances W1 and W2 is too large, there arises a problem that the electric resistance sewing becomes difficult.

Conversely, the distance W1 between the one end 12B and the center line of the weld may be smaller than the distance W2 between the other end 12A and the center line of the weld. In this case, the ridge 18
Since the waveform deformation can be prevented by this, the distance W1 can be reduced, and the distance W2 can be set relatively large, so that the waveform deformation occurring slightly on the other end portion 12A side of the fin 12 can be suppressed. Specifically, the distance W1 is about 10 to 30% of the pitch P or 0.05 to 0.2 mm more than the distance W2.
It may be as small as possible. However, also in this case, if the difference between the distances W1 and W2 is too large, there arises a problem that the electric resistance sewing becomes difficult.

The distance W3 from the tip of one end 12B of the fin 12 to the center of the ridge 18 is not necessarily limited in the present invention, but is preferably 10 to 1 of the fin pitch P.
About 000%, more preferably 100 to 6%.
00%. If the distance W3 is large, the problem of waveform deformation cannot be sufficiently improved. Conversely, if the distance W3 is too small, the flow of the heat medium is prevented by the one end 12B projecting between the ridge 18 and the welded portion 16. The trimming effect is reduced, and the tendency of the ridge 18 to block the swirling flow increases. That is,
If the ridge 18 intersects the end of the one end 12B in a T-shape, the heat medium tends to flow smoothly through the finless portion 20 between the ridge 18 and the welded portion 16, although the tendency is increased. ,
Since the one end portion 12B protrudes between the ridge portion 18 and the weld portion 16, the flow of the heat medium smoothly through the finless portion 20 is appropriately suppressed, and there is no fin over the ridge portion 18. The flow of the heat medium from the portion 20 to the groove portion 14 or the flow of the heat medium from the groove portion 14 to the finless portion 20 is made smooth, so that the swirling flow of the heat medium caused by the fins 12 is hardly obstructed, and the pressure loss is reduced. can do.

The amount of protrusion of the ridge 18 from the inner surface of the metal tube is
10 to 120% of the amount of protrusion of the fin 12 from the inner surface of the metal tube
It is preferred that In order to reduce the amount of protrusion, the width of the ridge 18 may be increased.
If it is less than 0%, the effect of sufficiently preventing the material flow along the groove portion 14 cannot be exerted, and the wave end deformation tends to occur at the end of the plate material. On the other hand, if it is larger than 120%, there is an effect on pipe expansion work and pressure loss. The value is more preferably 30
To 90%, and more preferably 60 to 80%.

Next, FIG. 3 is a side view showing an example of an apparatus for manufacturing the heat transfer tube with inner surface groove 10 having the above configuration. In the figure, reference numeral 30 denotes an uncoiler for continuously feeding out a metal plate strip T having a constant width. The fed plate strip T passes through a pair of holding rolls 32, and forms a pair of grooved rolls 34 and smooth rolls 36. 4 by a grooved roll 34 in FIG.
The fin 12, the groove 14, and the ridge 18 as shown in FIG.
Are simultaneously rolled, while the back surface is kept smooth.

As shown in FIG. 4, the grooved roll 34 has a grooved roll body 34A having a number of spiral fin rolling grooves 62 formed on the outer peripheral surface thereof, and substantially the same diameter coaxially fixed to both ends thereof. And a pair of side rolls 34B. As shown in FIG. 5, the fin rolling groove 6 is provided in the grooved roll body 34A.
On the roll center side from one end of the roll 2, a ridge rolling groove 60 extending in the circumferential direction is formed over the entire circumference, and the rolling groove 62 is formed.
Crosses at one end in a cross shape. The cross-sectional shape of the fin rolling groove 62 corresponds to the cross-sectional shape of the fin 12, and the cross-sectional shape of the ridge rolling groove 60 corresponds to the cross-sectional shape of the ridge 18. The fins 12 are rolled into the sheet material T by the fin rolling grooves 62, while the ridges 18 are rolled by the ridge rolling grooves 60. The dimensions and the like of each part are set so as to obtain a rolled shape as described above.

The outer peripheral surface of the central portion of the grooved roll body 34A has an accurate cylindrical surface, while the grooved roll body 3A has an accurate cylindrical surface.
The outer peripheral surface of both sides in the axial direction of 4A is
It may be a conical surface whose outer diameter decreases toward the side B. In this case, the thickness of the plate material T in both end portions 14 </ b> A of the spiral groove 14 is formed so as to gradually increase toward the protrusion 18. In this case, in the same part,
The depth of the rolled groove 62 is formed so as to gradually decrease toward both ends of the grooved roll main body 34A, whereby the height of the fins 12 formed in the plate material T is reduced to a portion 1 near the welded portion.
In 2A, the distance may decrease as approaching the ridge 18. Further, the outer peripheral surface of the side roll 34B may be a tapered surface whose outer diameter decreases outward in the axial direction, whereby the thickness of the finless portion 20 is greater than the thickness in the spiral groove 14. May also be set to be large.

As shown in FIG. 3, the sheet material T grooved by the grooved rolls 34 and the smoothing rolls 36 is gradually rounded into a plurality of forming rolls 40 through a pair of rolls 38, and into a plurality of forming rolls 40. The rolling separator 41 keeps a constant gap between both edges to be abutted with each other, and then passes through the induction heating coil 42 to heat both side edges. The plate material T which is formed into a tube and heated is passed through a pair of squeeze rolls 44, and is pressed from both sides so that the heated both side edges are abutted and welded. Since a bead is formed on the outer peripheral surface of the heat transfer tube 10 thus welded by the protruding molten material, a bead cutter 46 for cutting the bead is provided.

The heat transfer tube 10 from which the beads have been cut is placed in the cooling tank 4.
After being forced cooled through the sizing rolls 8, the sizing rolls 50 are arranged in a plurality of pairs, and are reduced in diameter to a predetermined outer diameter. Further, the reduced diameter heat transfer tube 10 is used for the rough coiler 5.
It can be wound up with 2.

Next, an embodiment of a method of manufacturing a heat transfer tube with an inner surface groove using the above apparatus will be described. In the method of this embodiment, first, a plate material T having a constant width is continuously fed out from the uncoiler 30, and the fed plate material T is passed through a pair of holding rolls 32, and is formed between a grooved roll 34 and a receiving roll 36. The fin 12, the spiral groove 14, and the ridge 18 as shown in FIG. 2 are formed by the grooved roll 34.

In this rolling process, the material pressed down to form the groove 14 flows along the groove 14 on the one end 12B side of the fin 12 shown in FIG. Since the material flow along the groove portion 14 is prevented by forming the protruding ridge portion 18 by the rolled groove 60, the material flow does not reach the side edge portion of the plate material T, and the waveform deformation does not occur. .

Next, the grooved plate material T is applied to a pair of rolls 38 and a plurality of paired forming rolls 4.
After gradually rounding into a tube through 0, the distance (gap amount) between both edges to be abutted by the rolling separator 41 is kept constant. Then, the two side edges are heated by passing through an induction heating coil 42, and a pair of squeeze rolls 4
By pressing from both sides through 4, the two side edges are butted and welded. At this time, since the projecting ridges 18 are formed, both side edges of the plate strip T are kept straight.
Uniform welding process is possible without uneven butting pressure or gap, but a highly reliable heat transfer tube 10 with inner groove is obtained.

Since the molten material protruding from the outer peripheral surface of the heat transfer tube 10 becomes a bead, the bead is cut by a bead cutter 46. Further, the heat transfer tube 10 from which the beads have been cut is forcibly cooled by passing through the cooling tank 48, and is reduced to a predetermined outer diameter through the sizing rolls 50 arranged in plural pairs.
The heat transfer tube 10 having the reduced diameter is wound up by the rough coiler 52. However, this step is a case where the apparatus of FIG. 3 is used, and it is needless to say that the step may be changed according to the configuration of the apparatus.

According to the heat transfer tube with an inner surface groove of this embodiment having the above-described structure, the method and the apparatus for manufacturing the same, the material flow along the groove 14 is prevented by rolling the protruding ridge 18, and the waveform is deformed. Can be prevented, the reliability of the welded portion 16 can be improved, and the ridge 1
8 is formed at a position closer to the center of the fin 12 than the one end portion 12B, and has a smaller height. Therefore, when the heat transfer tube is used, the heat medium flows over the ridge portion 18 and flows smoothly. It is difficult to hinder the swirling flow of the heat medium, and it is possible to reduce the pressure loss.

[Second Embodiment] FIGS. 6 and 7 show a second embodiment of the present invention. FIG. 6 is an enlarged view of the inner surface of a heat transfer tube 10 having an inner groove, and FIG. It is the elements on larger scale of the outer peripheral surface of a forming roll. In the above-described first embodiment, only one ridge 18 is formed. However, in the heat transfer tube with the inner surface groove according to the second embodiment, as shown in FIG. Parallel ridges 18
The present invention is characterized in that it is formed. As shown in FIG. 7, two ridged rolling grooves 60 are formed on one end of the grooved roll body 34 </ b> A in parallel. When two or more ridges 18 are formed as described above, the effect of preventing the waveform deformation by the ridges 18 is increased, and accordingly, the ridges 1 are correspondingly increased.
8 can be reduced, and the pressure loss can be further reduced. The distance W4 between the ridges 18 is not limited, but is preferably about 0.2 to 0.5 mm, and the effect of preventing waveform deformation is high. Other configurations may be the same as in the first embodiment.

[Third Embodiment] FIGS. 8 and 9 show a third embodiment of the present invention. FIG.
FIG. 9 is a partially enlarged view of the outer peripheral surface of a rolling roll for producing the same. In the heat transfer tube with an inner groove according to the third embodiment, as shown in FIG. 8, a short ridge 19 intersecting each end 12B of the fin 12 in a cross shape is formed along a straight line parallel to the tube axis. It is characterized by a large number being formed intermittently. In addition, the grooved roll body 34A includes:
As shown in FIG. 9, a ridge rolling groove 61 is formed intermittently on one end side. When the ridges 19 are formed in a discontinuous state as described above, the heat medium flows through the gaps 19A between the ridges 19 while preventing the waveform deformation to some extent, thereby obstructing the swirling flow of the heat medium. Pressure loss can be further reduced. The gap 19A of the ridge 19 is preferably about 10 to 50% of the fin pitch P. Other configurations may be the same as in the first embodiment.

[Fourth Embodiment] FIGS. 10 and 11 show a fourth embodiment of the present invention. FIG. 10 is an enlarged view of the inner surface of a heat transfer tube 10 having an inner surface groove, and FIG. It is the elements on larger scale of the outer peripheral surface of a roll. In the heat transfer tube with an inner surface groove according to the fourth embodiment, as shown in FIG. 10, a short ridge 19 crossing each end 12B of the fin 12 in a cross shape is formed by two straight lines parallel to the tube axis. It is characterized in that a large number are formed alternately along the top. In the grooved roll body 34A, as shown in FIG. 11, a ridge roll groove 61 is formed at one end side in a staggered manner along two parallel lines. When the ridges 19 are formed in a discontinuous state in this manner, the gap between the ridges 19 is larger than in the third embodiment in which the ridges 19 have the same length, so that the heat medium is swirled. The flow is hardly hindered, and the pressure loss can be further reduced.

In each of the above embodiments, the ridges 18 or 19 are formed only on one side of the welded portion 16. However, if necessary, the other end portion 12A of the fin on the opposite side of the welded portion 16 may be formed. May also form ridges 18 or 19. In this case, since the problem of waveform deformation is small on the other end 12A side, the height of the ridge on the other end 12A side is lower than that on the one end 12B side. 20-6
It may be 0%. The shape of the fin is not limited to the spiral shape, and may be changed to a V-shape or a W-shape if necessary.

[0040]

Next, the effects of the present invention will be demonstrated with reference to examples. When the inner grooved heat transfer tube 10 shown in FIG. 2 is manufactured using the grooved roll 34 having the shape shown in FIG. 5 (the method of the present invention), the groove 60 for forming the ridge portion in FIG. 5 is formed. The only difference is that the shape and dimensions of the other end are the same as in the case where the inner grooved heat transfer tube is manufactured using grooved rolls of the same shape and dimensions (Comparative Example method). Were compared.

The rolling conditions are as follows. Initial thickness of the strip material T: 0.44 mm Material of the strip material T: Phosphorus deoxidized copper Height of the fin 12: 0.20 mm Pitch of the fin 12: 0.44 mm Angle of both side surfaces of the fin 12 (vertex angle) ): 53 ° Bottom width of the spiral groove 14: 0.20 mm Thickness of the plate material T: 0.30 mm Depth of the ridge forming groove 60: 0.15 mm From the center line of the ridge forming groove 60 Distance to the end face of the strip material T: 5 mm

As a result, in the strip material T obtained by the method of the present invention, no undulation was generated on the end face, whereas in the method of the comparative example in which the groove 60 for forming the ridge portion was not formed, A clear wavy shape occurred on the end face of the strip T.

[0043]

As described above, according to the heat transfer tube with an inner surface groove, the method and the apparatus for manufacturing the same according to the present invention, the formation of the ridge prevents material flow along the groove at the time of fin rolling. However, since it is possible to prevent waveform deformation, the reliability of the welded portion can be increased, and the ridge portion is formed at a position closer to the center of the fin than the end of the fin, and the height is small. In addition, when the heat transfer tube is used, the heat medium flows smoothly over the ridges, and it is difficult to hinder the swirling flow of the heat medium caused by the fins, and it is possible to reduce the pressure loss of the heat medium flow.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a heat transfer tube with an inner surface groove according to the present invention.

FIG. 2 is an enlarged view showing the vicinity of a welded portion of the heat transfer tube with internal groove.

FIG. 3 is a side view showing one example of a manufacturing apparatus of the heat transfer tube with inner grooves.

FIG. 4 is a plan view showing a rolling roll of the manufacturing apparatus.

FIG. 5 is an enlarged view of an outer peripheral surface showing a rolling roll of the manufacturing apparatus.

FIG. 6 is an enlarged view showing the vicinity of a welded portion of a heat transfer tube with an inner surface groove according to a second embodiment.

FIG. 7 is an enlarged view of an outer peripheral surface of a roll formed by the inner grooved heat transfer tube.

FIG. 8 is an enlarged view showing the vicinity of a welded portion of a heat transfer tube with an inner surface groove according to a third embodiment.

FIG. 9 is an enlarged view of an outer peripheral surface of a roll formed by the inner grooved heat transfer tube.

FIG. 10 is an enlarged view showing the vicinity of a welded portion of a heat transfer tube with an inner surface groove according to a fourth embodiment.

FIG. 11 is an enlarged view of an outer peripheral surface of a roll formed by the inner grooved heat transfer tube.

FIG. 12 is a plan view showing a method for manufacturing a conventional heat transfer tube with an inner surface groove.

FIG. 13 is an enlarged view of a side edge portion of a plate member showing a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat transfer tube with internal groove 12 Fin 12B One end of fin (downstream end in the rolling direction) 12A The other end of fin (upstream end in the rolling direction) 14 Spiral groove 16 Welded part 18, 19 Ridge part 20 No fin Part T Plate strip material 34 Grooved roll 36 Receiving roll 40 Forming roll 42 Induction heating coil 60, 61 Ridged groove 62 Fin roll groove

Claims (3)

[Claims] 1. A welded portion extending in the axial direction of the metal tube on an inner peripheral surface of the metal tube, finless portions formed in a strip shape on both sides of the welded portion, these finless portions, and In a range excluding the welded portion, there are a number of fins formed to be inclined with respect to the pipe axis, and one or more ridges crossing these fins in a cross shape at one end of the fins. A heat transfer tube with an inner surface groove, wherein the height of these ridges is 10 to 120% of the height of the fins. 2. A strip-shaped fin-free portion along both side edges of the plate-shaped strip is provided on one surface of the plate-shaped strip by passing the metal plate-shaped strip through a pair of fin forming rolls. A large number of fins extending in a slanting manner with respect to the longitudinal direction of the plate material, and a number of the fins intersecting at least one end of the fins in a cross shape, Rolling one or two or more ridges that are 10 to 120% of the ridges and the fins through a plurality of forming rolls through the plate material on which the ridges and the fins are formed. An inner surface comprising: a tube forming step of forming a tube so that is located on the inner peripheral side; and a welding step of heating and butt-welding both end edges of the plate-shaped plate member formed into a tube. How to manufacture grooved heat transfer tubes . 3. A rolling mechanism for rolling a metal plate material through at least one pair of rolling rolls while running the metal plate material to form a roll on at least one surface of the plate material. A pipe forming mechanism for forming the formed strip material into a tubular shape through a plurality of forming rolls, and a welding mechanism for heating and butt-welding both end edges of the tubular shaped strip material. Comprising, on the outer peripheral surface of the rolling roll facing one surface of the plate material,
A grooveless portion for forming a band-shaped finless portion along both side edges of the plate-like material, and a number of fins which are arranged in a large number in a region sandwiched between these grooveless portions and extend obliquely with respect to the roll circumferential direction. A device for manufacturing a heat transfer tube with an inner surface groove, wherein a rolled groove and one or more ridged rolled grooves crossing at least one end of the fin rolled groove in a cross shape are formed. .