JPH09155443A - Manufacturing method and device of heat tube with groove in inner surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of not only preventing the generation of a corrugated shape in the end surface of a sheet stock without making grooving difficult but also improving the reliability of a heat tube. SOLUTION: This method is provided with a grooving process wherein many grooves 3 are formed on at least one side surface of the bar stock T by passing between at least a pair of grooving rolls 14 and 16 while running the bar stock T made of a copper or copper alloy, a tube forming process wherein the bar stock T formed grooves 3 is formed into a tube through plural forming rolls and a welding process wherein both end edges of the bar stock T formed into the tube are heated and butted to weld. Many projecting streak part 42 corresponding to grooves 3 to be formed in the bar stock T are formed on the outer periphery of a grooved roll 14 which is at least one of a pair of grooving rolls, and the surface roughness of the chip surfaces of these projecting streaks 42 is set to be 0.3-1.2μmRa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a heat transfer tube with an inner groove, which employs an electric resistance welded pipe method.

[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. A heat transfer tube in which spiral fins are formed between grooves by forming such grooves is widely commercially available.

The heat transfer tube, which is currently the mainstream, is a metal tube obtained by passing a floating plug having a spiral groove formed on the outer peripheral surface inside a seamless (seamless) tube obtained by drawing or extruding. It is manufactured by a method of rolling a spiral groove over the entire inner peripheral surface of the fin.However, this manufacturing method limits the shape and height of the fin due to the characteristics of the floating plug. There is a limit to improving the heat transfer efficiency by improving the heat transfer efficiency.

[0006] Therefore, the inventors of the present invention, instead of the seamless tube, a "electric resistance welded pipe method" in which a long metal plate material is rolled in the width direction and welded at both side edges which are abutted to each other to obtain a metal tube.
We have been studying the adoption of heat transfer tubes for manufacturing.
According to the electric resistance welded pipe method, the fins to be formed on the inner surface of the heat transfer tube can be rolled in the state of the flat metal plate material, and the degree of freedom in designing the fin shape is high.

FIG. 5 shows an example of a heat transfer tube with an inner groove manufactured by the electric resistance welded pipe method. This heat transfer tube 1 is a metal tube having a circular cross section, and a large number of parallel fins 2 forming a constant angle with the tube axis are spirally formed over almost the entire inner surface of the heat transfer tube 1. The spaces are spiral grooves 3, respectively. In addition, a welded portion 4 is formed by electric sewing at one location on the inner peripheral surface of the heat transfer tube 1, and finless portions 5 extending parallel to the central axis of the heat transfer tube 1 are formed on both sides of the welded portion 4.
Is formed, and each fin 2 is formed by this finless portion 5.
Has been divided.

[0006]

By the way, in the manufacturing of the heat transfer tube with the inner groove by the conventional electric resistance welding method, as shown in FIG. 6, both side edges of the plate material T do not have a linear shape 5A, It was found that the shape was slightly wavy 5B. If such a corrugated shape 5B is generated, a gap may be formed on the abutting surfaces in the welding process, and the quality of the welded portion may become uneven. Therefore, when the corrugated shape 5B is remarkable, the reliability of the welded portion is improved. In order to increase the height, it was necessary to cut off both side edges to form a straight line.

In particular, according to the recent research by the present inventors,
It has been found that the fins of the heat transfer tube with internal groove can be made larger than the conventional product and the fin cross section can be made thinner to improve the condensation performance and evaporation performance. In the case of forming ridges, there was also a problem that the corrugated shape 5B became more prominent.

Therefore, the present inventors have made a detailed study on the mechanism of generating the wavy shape 5B as shown in FIG. 6, and have obtained the following findings. That is, in the portion where the spiral groove 3 is to be formed, the material reduction rate is larger than that in the portion where the fin 2 is to be formed, so that the material flows from the end of each spiral groove 3 toward the finless portion 5. For this reason, the edge relatively projects at the location corresponding to the end of each spiral groove 3, and the corrugated shape 5B is generated.

By the way, the present inventors have found that such a wavy shape 5B does not always occur with the same strength, and the wavy shape 5B is suppressed in a certain case. Therefore, a detailed study was conducted under which conditions the corrugated shape 5B is unlikely to occur. In particular, it was found that there is a correlation with the surface roughness of the outer peripheral surface of the grooved roll for forming grooves in the sheet material. I found it. That is, when the surface roughness of the outer peripheral surface of the grooved roll (actually, the tip end surface of the protruding portion formed on the outer peripheral surface) is made larger than usual (about 0.2 μmRa is common), the wavy shape 5B The occurrence of
Furthermore, the fact that a high fin can be easily formed with a relatively small rolling down force was found. However, it was also found that if the surface roughness is made too large, the central portion of the strip material in the width direction is slackened to form irregularities, which hinders pipe forming.

The present invention has been made on the basis of the above findings, and it is possible to prevent the corrugated shape from being generated on the end face of the strip material without making the groove processing difficult, and to improve the reliability of the heat transfer tube. It is an object to provide a manufacturing method and a manufacturing apparatus for a grooved heat transfer tube.

[0011]

In order to achieve the above object, a method for manufacturing an inner grooved heat transfer tube according to the present invention is provided with at least a pair of groove forming rolls while running a sheet material made of copper or copper alloy. A groove forming step of forming a large number of grooves on at least one surface of the plate material through the space, a tube forming step of forming the grooved plate material into a tubular shape through a plurality of forming rolls, and a tubular shape A method of manufacturing a heat transfer tube with an inner surface groove, comprising a step of heating both end edges of the strip material and butt-welding the strip material, wherein at least one outer peripheral surface of the pair of groove forming rolls is provided. ,
A large number of ridges corresponding to the grooves to be formed in the plate material are formed, and the surface roughness of the tip surfaces of these ridges is 0.3 to
It is characterized by being set to 1.2 μmRa.

The thickness of the strip material before groove formation is 0.3 to
1.2 mm, the depth of the groove formed in the strip is 2 of the above thickness
It is more preferably 0 to 60%. Deoxidized copper is more preferably used as the strip material. Furthermore, it is more preferable that the Vickers hardness of the plate material before groove formation is 50 to 150 Hv. However, the present invention is not limited to these ranges.

On the other hand, in the apparatus for producing a heat transfer tube with an inner groove according to the present invention, while a strip material made of copper or a copper alloy is running, at least one surface of the strip material is passed through at least a pair of groove forming rolls. Groove forming mechanism for forming the groove, a tube forming mechanism for forming the plate material having the groove formed into a tubular shape through a plurality of forming rolls, and both ends of the tubular material formed into a tubular shape. An apparatus for manufacturing a heat transfer tube with an inner groove, comprising: a welding mechanism for heating the edges and then butt-welding the at least one outer peripheral surface of the pair of groove-forming rolls with a plate material. A large number of ridges corresponding to the grooves to be formed are formed, and the surface roughness of the tip surfaces of these ridges is set to 0.3 to 1.2 μmRa.

[0014]

1 is a side view showing an embodiment of an apparatus for manufacturing a heat transfer tube with an inner groove according to the present invention. In the figure, reference numeral 10 is an uncoiler for continuously feeding a strip material T having a constant width. The strip material T fed out passes through a pair of pressing rolls 12 and then a pair of grooved rolls 14 and smoothing rolls 16 (both (Collectively referred to as groove forming rolls),
The grooved roll 14 forms the fin 2 and the spiral groove 3 as shown in FIG. In this embodiment, the fins 2 and the spiral grooves 3 are formed only on the front surface S1 of the strip material T, and the back surface S2 is left smooth.

2 to 4 are detailed views of the grooved roll 14 and the smooth roll 16, and the rolls 14 and 16 are rotatably supported by a frame 38 via shafts 34 and 36, respectively. As shown in FIG. 4, the grooved roll 14 includes a grooved roll main body 14A having a rolling groove 40 formed on the outer peripheral surface thereof, and a pair of side rolls 14B fixed to both sides thereof. The fins 2 are formed on the plate material T by the rolling grooves 40, while the ridges 4 between the rolling grooves 40 are formed.
The spiral groove 3 is formed by 2.

The main feature of this embodiment is that the leading end of the projection 42 of the grooved roll 14 is a substantially flat surface and the surface roughness is 0.3 to 1.2 μmRa. The surface roughness is more preferably 0.5-1.
0, and more preferably 0.6 to 0.9 μmRa. By setting the surface roughness to 0.3 to 1.2 μmRa, it is possible to prevent the corrugated shape from being generated on the end face of the strip material without being significantly affected by other conditions, and thus to improve the reliability of the heat transfer tube. The present inventors have found that it can be improved. The cause of this is not clear, but by setting the surface roughness in the above range, it is possible to prevent the occurrence of corrugated shapes on the end face of the strip material, and to reduce the rolling force to obtain the required fin height. The inventors have discovered. The cause of this is not clear, but it is considered that when the surface roughness is in the above range, the elongation of the material along the surface direction is suppressed to some extent.

When the surface roughness is less than 0.3 μmRa,
The elongation of the strip material T in the plane direction becomes remarkable, and therefore, the corrugated shape 5B as shown in FIG. 6 is likely to occur on the end surface of the strip material T. In addition, since the material flows in the surface direction and does not easily reach the inside of the rolling groove 40 of the grooved roll 14, it is difficult to form the fin 2 high. Therefore,
If the high fins 2 are to be formed, the rolling force (rolling pressure) of the grooved rolls 14 and the driving force of the sheet material T required for fining increase, which increases the production cost of the heat transfer tubes. In the conventional method and apparatus for manufacturing the inner grooved heat transfer tube, attention was not paid to the surface roughness of the grooved roll 14, and therefore the surface was made much smoother than 0.3 μmRa. On the other hand, when the surface roughness is larger than 1.2 μmRa, as shown in FIG. 7, the material is stretched only in the central portion of the strip material T, and a large number of elliptical slacks 5C are generated (medium stretch). It is difficult to perform electric resistance sewing. The outer peripheral surface of the smooth roll 16 also has a surface roughness of 0.3 to 1.
It is preferably 2 μmRa.

The edge of the boundary between the protrusion 42 and the rolling groove 40 may be chamfered or chamfered, but the chamfer having a radius of curvature of about 0.02 to 0.07 mm is chamfered. Is more preferable. The outer peripheral surface of the side roll 14B is a tapered surface whose outer diameter decreases toward the outside in the axial direction. This is because both side edges of the plate material T when the fins 2 are formed on the plate material T. This is in consideration of the fact that 44 is curved back to the side roll 14B side.

As shown in FIG. 1, the sheet material T grooved by the grooved rolls 14 and the smooth rolls 16 is gradually rolled into a tubular shape through a pair of rolls 18 and a plurality of pairs of forming rolls 20. The seam guide roll 21 keeps the gap between the opposite edges to be abutted constant, and the side edges are heated by the induction heating coil 22. Plate material T formed into a tube and heated
Is passed through a pair of squeeze rolls 24, and the both side edges heated by being pushed from both sides are butted,
Welded. A bead cutter 26 for cutting the bead is provided on the outer peripheral surface of the heat transfer tube P welded in this way, because a bead is formed by the molten material protruding.

The heat transfer tube P whose bead is cut is the cooling tank 28.
After being passed through and forcedly cooled, a plurality of pairs of sizing rolls 30 are passed through and the diameter is reduced to a predetermined outer diameter. The heat transfer tube P thus reduced in diameter is wound up by the rough coiler 32.

Next, an embodiment of a method for manufacturing a heat transfer tube with an inner surface groove using the above apparatus will be described. In the method of this embodiment, first, the strip material T having a constant width is continuously fed from the uncoiler 10, and the strip material T fed is passed between the grooved roll 14 and the receiving roll 16 through the pair of pressing rolls 12. The fin 2 and the spiral groove 3 are formed by the grooved roll 14 through the gap.

Both sides S1 of the strip material T used in this method
The surface roughness of S2 is preferably 0.05 to 0.30 μm.
Ra, more preferably 0.07 to 0.20 μmRa, further preferably 0.10 to 0.17 μmRa.
The surface roughness of the sheet material T is preferably the same on both surfaces S1 and S2, but may not be the same as long as it is within the above range. It has been clarified by the present inventors that by setting the surface roughness of the strip material T in the above range, it is possible to further prevent the corrugated shape from being generated on the end face of the strip material. The cause of this is not clear, but it is considered that when the surface roughness of the plate material T is in the above range, the elongation of the material becomes more appropriate.

As the material of the strip material T, any material can be used as long as it is copper or a copper alloy. In particular, deoxidized copper (eg JIS 12) which is widely used as a material for heat transfer tubes.
20 alloy), the effect of the present invention is remarkable. However, the present invention is not limited to application to this material, and the same effect can be obtained when applied to oxygen-free copper, tough pitch copper, brass, brass, admiralty brass, and the like.

In any of the materials, the Vickers hardness of the strip material T immediately before the groove formation is preferably 50 to 150 Hv. This is because if it is in this range, the effect of preventing the generation of the wavy shape is further enhanced, and the driving force required for groove rolling can be reduced. However, the effect of the present invention can be obtained even if it is out of this range. The hardness of the plate material T is more preferably 50 to 100 Hv. The crystal grain size of the sheet material T is preferably 0.005 to 0.04 mm, and more preferably 0.01 to 0.03 mm. This is because if it is within this range, the effect of preventing the generation of the corrugated shape on the end face of the strip material T is further enhanced. However, the effect of the present invention can be obtained even if it is out of this range.

It should be noted that the present invention has a general outer diameter of 3 to 15 mm.
When applied to the production of a heat transfer tube of a certain degree, the thickness of the strip material T before the groove formation is preferably 0.3 to 1.2 mm, and the depth of the spiral groove 3 formed in the strip material T is preferably. The thickness (= height of the fin 2) is preferably 20 to 60% of the thickness of the plate material T. In particular, in the present invention, the height of the fins 2 is higher than that of the conventional product, that is, the thickness of the plate material T is 4 times as large as that of the conventional product while preventing the generation of the wavy shape on both side edges of the plate material T.
It can be increased to 0 to 60%. In this case, the drainage property and the turbulent flow generation effect at the tips of the fins 2 are improved, and high heat exchange performance that cannot be obtained by the conventional seamless pipe is obtained. Have advantages.

Next, as shown in FIG. 1, the grooved plate material T is gradually rolled into a tubular shape through a pair of rolls 18 and a plurality of forming rolls 20 arranged in a plurality of pairs, and then a seam guide roll 21 is used. The distance (gap amount) between both edges to be butted is kept constant. Then, the both side edges are heated by passing through the induction heating coil 22, and further pushed by pushing the pair of squeeze rolls 24 from both sides, so that the both side edges are abutted and welded. Since the molten material protruding to the outer peripheral surface of the heat transfer tube P becomes a bead, the bead cutter 26 cuts this bead.

The heat transfer tube P whose bead is cut is placed in the cooling tank 28.
Through a sizing roll 30 in which a plurality of pairs are arranged, and the diameter is reduced to a predetermined outer diameter. The heat transfer tube P thus reduced in diameter is wound up by the rough coiler 32. However, this step is for the case where the apparatus of FIG. 1 is used, and it goes without saying that it may be changed according to the configuration of the apparatus.

According to the manufacturing method and the manufacturing apparatus for the inner grooved heat transfer tube of this embodiment having the above-mentioned structure, the tip end of the protruding portion 42 of the grooved roll 14 is made substantially flat, and the surface roughness thereof is Since it is set to 0.3 to 1.2 μmRa,
The elongation of the material is appropriately suppressed, and when the groove rolling is performed by the grooved roll 14, the material is suppressed from flowing from the groove forming portion having a large reduction amount to both side edge portions of the sheet material T, and the groove rolling is performed. It is possible to prevent the corrugated shape 5B from being generated on both side edges of the subsequent plate material T. Nevertheless, the rolling pressure and driving force required for groove machining do not increase significantly, so there is no risk of increasing the production cost of the heat transfer tube. Therefore, there is an excellent effect that the highly reliable heat transfer tube with inner groove can be manufactured at the same cost as the conventional one.

In the above embodiment, the fins 2 and the spiral groove 3 are formed only on the inner surface of the heat transfer tube 1. However, in the present invention, the fins and grooves are formed on the outer surface of the heat transfer tube or on the inner surface and the outer surface. It is also applicable to. Also in this case, at least the outer peripheral surface of the grooved roll is 0.3 to 1.2 μmRa.
And it is sufficient. Further, in the above embodiment, the grooved roll 1
Although the 1-step groove rolling was carried out in accordance with No. 4, two or more grooved rolls were used to form the groove in two or more steps, and cross grooves formed by intersecting two kinds of grooves were formed on the inner surface of the heat transfer tube and It is also possible to form it on the outer surface, and / or in this case, the same effect as described above can be obtained. At this time, the outer peripheral surface of each of the two grooved rolls may be 0.3 to 1.2 μmRa. Further, according to the method of the present invention, not only is it possible to form spiral fins or spiral grooves extending over the entire width of the strip material, but also short fins divided in the longitudinal direction are staggered or along spiral lines. It is also possible to form a large number.

[0030]

EXAMPLES Next, the effects of the present invention will be demonstrated with reference to examples. [Experiment 1] Using an annealed sheet material made of deoxidized copper (C1220), an internal grooved heat transfer tube was manufactured by the apparatus shown in FIG. At that time, only the surface roughness is variously changed by changing the polishing condition of the outer peripheral surface of the grooved roll 14, while the other conditions are unified to change the roll rolling force and the strip material after rolling. It was confirmed whether or not a wavy shape was generated on the end surface of No. 1, a welding defect was generated, and an intermediate elongation was generated. The shape of the intended heat transfer tube with inner groove is as follows. Outer diameter: φ9.52 mm Thickness of metal pipe excluding fins: 0.30 mm Height of the fin from the inner peripheral surface of the pipe: 0.20 mm Number of fins (number of threads) in the pipe cross section: 60 Both side faces of the fin Angle (vertical angle): 53 ° Helix angle (lead angle) with respect to the tube axis of the fin: 18 °

Other common conditions are as follows. Dimensions of strip material: thickness of 0.44 mm x width of 33 mm Average grain size of strip material: 0.015 mm Average hardness of strip material: 56 Hv Surface roughness of strip material T: 0.15 μmRa Smooth roll 16 outer peripheral surface roughness: 0.80 μm Ra

The results are shown in Table 1. In the table, "quality of plate end face shape" means whether or not a wavy shape is generated, and "x" indicates that a wavy shape is generated that makes welding difficult.
“△” indicates that welding was possible but a clear wavy shape occurred, and “○” indicates that a slight wavy shape occurred.
“A” indicates that no wavy shape was observed. "Medium elongation" means the occurrence of slack in the central part of the strip material, "x" indicates the occurrence of medium elongation that makes welding difficult, and "△" indicates that welding is possible but clear. In the figure, “◯” indicates that a slight amount of middle elongation was generated, and “⊚” indicates that no middle elongation was observed. "Good or bad of the weld" means the soundness of the weld,
“X” indicates that a clear welding defect occurred, and “△”
Indicates that a welding defect that does not affect airtightness has occurred, “○” indicates that there is a slight visual abnormality that is practically no problem, and “◎” indicates that there is no abnormality in the welded part. It means that it was not possible.

[0033]

[Table 1]

As is clear from Table 1, the grooved roll 14
When the surface roughness of the outer peripheral surface was 0.3 to 1.2 μmRa, the roll rolling force was small, and the corrugated shape, welding defects, and intermediate elongation did not occur.

[Experiment 2] Using a strip material made of deoxidized copper (C1220), an internal grooved heat transfer tube having fins higher than those in Experiment 1 was manufactured by the apparatus shown in FIG. The experimental method is the same as in Experiment 1. The shape of the intended heat transfer tube with inner groove is as follows. Outer diameter: φ9.52 mm Thickness of metal pipe excluding fins: 0.30 mm Height of fin from inner peripheral surface of pipe: 0.30 mm Number of fins (number of threads) in pipe cross section: 50 Both sides of fin Angle (vertical angle): 40 ° Spiral angle (lead angle): 18 ° with respect to the tube axis of the fin

Other common conditions are as follows. Dimensions of plate material: thickness 0.53 mm x width 33 mm Average hardness of plate material: 51 Hv Average grain size of plate material: 0.018 mm Surface roughness of plate material T: 0.11 μmRa Smooth roll Roughness of outer peripheral surface of 16: 0.80 μmRa Table 2 shows the results. The evaluation method is the same as in Experiment 1.

[0037]

[Table 2]

As is clear from Table 2, even when the fins higher than the conventional one are formed, if the surface roughness of the outer peripheral surface of the grooved roll 14 is 0.3 to 1.2 μmRa, the roll rolling force is reduced. Was small, and neither wavy shape, welding defect, nor middle elongation occurred.

[0039]

As described above, according to the manufacturing method and the manufacturing apparatus for the inner surface grooved heat transfer tube according to the present invention, the protrusions are formed on the outer peripheral surface of at least one of the groove forming rolls. Roughness of the tip surface of the part is 0.3 to 1.2
Since it is set to μmRa, the elongation of the material is appropriately suppressed when the groove is rolled by the groove forming roll, and the material locally flows from the groove forming portion with a large reduction amount to both side edges of the strip material. This can be suppressed, and the corrugated shape can be prevented from occurring on both side edges of the strip material after the groove rolling. Moreover, since the rolling pressure and the driving force required for the groove processing do not increase remarkably, there is an effect that the production cost of the heat transfer tube is not increased.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of an apparatus for manufacturing a heat transfer tube with an inner groove according to the present invention.

FIG. 2 is a side view showing the vicinity of a grooved roll of the same device.

FIG. 3 is a front view showing the periphery of a grooved roll of the apparatus.

FIG. 4 is a vertical sectional view showing the periphery of a grooved roll of the apparatus.

FIG. 5 is a cross-sectional view showing an example of a heat transfer tube with an inner surface groove obtained by the method of the present invention.

FIG. 6 is an enlarged view of an end portion of a strip material showing a problem of the conventional method.

FIG. 7 is an enlarged view of a strip material showing a problem when the roll surface roughness is too large.

[Explanation of symbols]

 1, P Heat transfer tube 2 Fin 3 Spiral groove 4 Welded portion 5 Finless portion T Plate material S1, S2 Both sides of plate material 14 Grooved roll 16 Receiving roll 20 Forming roll 40 Rolled groove 42 Protruded rib

Front page continuation (72) Inventor Haruo Kono 128-7 Ogimachi, Aizuwakamatsu, Fukushima Mitsubishi Shindoh Co., Ltd. Wakamatsu Manufacturing Co., Ltd. (72) Inventor Rizo Nishimaki 128-7 Ogimachi, Aizuwakamatsu, Fukushima Mitsubishi Shindoh Co., Ltd. Wakamatsu Plant (72) Inventor Yoshihito Haga 128-7 Ogimachi, Aizu-Wakamatsu City, Fukushima Prefecture 7 Mitsubishi Shindoh Co., Ltd. Wakamatsu Plant (72) Takashi Kazama 128-8 Ogimachi, Aizuwakamatsu City, Fukushima Prefecture Wakamatsu Works, Mitsubishi Shindoh Co., Ltd. Within

Claims (5)

[Claims] 1. A groove forming step of forming a large number of grooves on at least one surface of the sheet material while passing a sheet material made of copper or a copper alloy and passing between at least a pair of groove forming rolls. Inner surface groove including a tube forming step of forming the formed sheet material into a tubular shape through a plurality of forming rolls, and a welding step of heating both end edges of the sheet material formed into a tubular shape and then abutting and welding the same. A method for manufacturing a heat transfer tube with a plurality of protrusions is formed on at least one outer peripheral surface of the pair of groove forming rolls, the protrusions corresponding to the grooves to be formed in the plate material. A method for manufacturing a heat transfer tube with an inner groove, wherein the surface roughness of the tip end surface of the ridge is set to 0.3 to 1.2 μmRa. 2. The thickness of the strip material before forming the groove is 0.3 to
1.2 mm, and the depth of the groove formed in the strip material by the groove forming roll is 20 to 60% of the thickness of the strip material.
The method of manufacturing a heat transfer tube with an inner groove according to claim 1, wherein 3. The method for producing a heat transfer tube with an inner groove according to claim 1, wherein the plate material is made of deoxidized copper. 4. The Vickers hardness of the sheet material before forming the groove is 50 to 150 Hv.
3. The method for manufacturing a heat transfer tube with an inner groove according to any one of 3 above. 5. A groove forming mechanism for forming a large number of grooves on at least one surface of the plate material while passing a plate material made of copper or copper alloy and passing between at least a pair of groove forming rolls, A tube forming mechanism for forming a sheet material having grooves formed therein into a tubular shape through a plurality of forming rolls, and a welding mechanism for welding both ends of the sheet material formed into a tubular shape by heating and then abutting each other. An apparatus for manufacturing a heat transfer tube with an inner groove, comprising: a plurality of protrusions corresponding to the grooves to be formed in the plate member on at least one outer peripheral surface of the pair of groove forming rolls. An apparatus for manufacturing a heat transfer tube with an inner surface groove, wherein the surface roughness of the tip end surfaces of these ridges is set to 0.3 to 1.2 μmRa.