JPH03133514A - Flat grooved pipe and manufacture thereof - Google Patents

Abstract

PURPOSE:To drastically improve a heat transfer efficiency, by limiting the inter-inner peripheral face dimension in the short size direction of a flat grooved pipe, specifying the ratio to the inter-inner peripheral face dimension in the long size direction as well, approaching each side wall of the groove mutually according to its separation from the bottom wall and limiting the pitch between the grooves. CONSTITUTION:The dimension H between the inner peripheral faces in the short size direction of the section orthogonal with the axial line of the flat grooved pipe 1 that plural grooves A are formed on the inner peripheral face is formed in 1mm min.-5mm max. and also the ratio of the dimension W between the inner peripheral face in the long size direction to the above dimension between the inner peripheral faces in the short size direction is formed at >=3. Also, the grooves A are formed so as to approach mutually according to each side wall A2 which rises from the both side edges of the bottom wall A1 being separated from the bottom wall A1 and also the pitch between adjacent grooves A is formed in 0.25mm min. and 0.7mm max. The efficiency of heat transfer is therefore improved and also the forming is executed while holding a floating plug work pipe from the inside, so a flat grooved pipe of good flatness is obtainable even in the case of the breadth / length of the dimension between the inner peripheral faces being a large oblateness of >=3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flat grooved tube having a plurality of grooves formed on its inner circumferential surface, and a method for manufacturing the same.

[Prior Art] In recent years, metal tubes used as heat exchanger tubes have been adopted as flat grooved tubes, which have a plurality of grooves Fk on the inner surface and are formed in a flat shape, in order to improve heat exchange efficiency. .

This type of flat grooved tube can be made by forming a flat tube by extrusion, by roll forming a welded circular tube into a flat shape, or by simply pulling a cylindrical tube through a die. It is manufactured by molding it into a shape.

[Problems to be Solved by the Invention] However, the above-mentioned conventional flat grooved tubes are not manufactured with sufficient consideration of heat transfer efficiency in terms of the aspect ratio and the shape of the grooves, so they are still unsatisfactory in terms of heat transfer efficiency. There was a point.

The present invention has been made in view of the above circumstances, and aims to provide a flat grooved tube with higher heat transfer efficiency and a method for manufacturing the flat grooved tube.

[Means for Solving the Problems] In order to achieve the above object, the flat grooved tube of the present invention has a plurality of grooves A formed in the inner circumferential surface thereof extending in a direction crossing a cross section perpendicular to the axis. In the flat grooved tube, the vertical dimension, which is the dimension between the inner circumferential surfaces in the short direction in the orthogonal cross section, is formed to be 1 mm or more and 5n+m or less, and the length between the inner circumferential surfaces in the long direction of the orthogonal cross section is 1 mm or more and 5n+m or less. The i74A has a width/height ratio of 3 or more between the horizontal dimension and the vertical dimension, and the i74A has side walls rising from both side edges of the bottom wall that move toward each other as they move away from the bottom wall. The grooves are formed so as to be close to each other, and the pitch between the adjacent RA and the groove is 0.25 mm or more and 0.7 mm or less.

In addition, as a manufacturing method for the above-mentioned flat grooved tube, a cylindrical workpiece tube with a plurality of grooves B formed on its inner peripheral surface is reduced in diameter with a drawing die, and the inside of the workpiece tube whose diameter has been reduced with the drawing die is The to-be-processed pipe is pressed with a flattening die onto a flattened portion formed at the other end of the floating plug, one end of which is held in the diameter-reduced portion and the other end extends downstream in the drawing direction. In this way, the pipe to be processed is formed into a flat shape, and the top of the ridge between the grooves B on the inner circumferential surface is compressed and plastically deformed to change the width of the top of the ridge to that of the base end. To provide a method of forming a product wider than its width.

The reason for limiting the dimensions to two feet will be explained below.

The reason why the vertical dimension between the inner circumferential surfaces in the short dimension direction is set to 1 mm or more and 5 mm or less is because if it is less than 1 mm, the passage resistance of heat medium such as freon will be high, and if it exceeds 5 mm, it will pass through the official mark of the flat tube. This is because the heat medium becomes difficult to evaporate.

The width/height ratio, which is the ratio between the inner peripheral surfaces in the long and short directions, is set to 3 or more when the vertical dimension is 1 mm or more and 5 mm or more.
This is because if the width/length is not set to 3 or more, the area through which the heat medium passes will become small and the resistance to the heat medium will increase.

i? The reason why the pitch between the grooves is set to 0.25 mm or less and 0.7 mm or more is because if the pitch is less than 0.25 mm, the grooves will become too dense and it will be difficult for the heat medium to penetrate into the grooves, making it difficult to improve heat transfer efficiency. This is because it will not be possible to aim sufficiently, and also 0.7 mm.
If it exceeds , the interval between the grooves will become too large, and in this case, it will not be possible to sufficiently improve the heat transfer efficiency.

[Function] In the flat grooved pipe of the present invention, the grooves A are formed so that they approach each other as they move away from the side wall or the bottom wall, so the surface area of the peaks formed between the grooves A is large. This improves heat transfer efficiency.

Moreover, since the pitch between the grooves A is set to 0.25 mm to 0.7 mm, the heat medium can flow into the groove A without resistance, and can be efficiently flowed through the side and bottom walls of the groove A. Heat will be transferred better.

In addition, in the method for manufacturing flat grooved tubes, the tube to be processed is formed into a flat shape while the inner peripheral surface of the tube is pressed against the floating plug, so the width of the top of the crest between the grooves is smaller than that of the base end. It becomes wider compared to its width. That is, the side walls of the groove B are shaped so that they approach each other as they move away from the bottom wall.

Moreover, since the pipe to be processed is held from the inside with a floating plug, even when the vertical dimension between the inner peripheral surfaces in the short dimension direction is 1 mm or more and 5 mm or less, and the horizontal/vertical ratio is 3 or more, the aspect ratio is large. , it is possible to manufacture a flat grooved tube with good flatness of the wall surface of the flat part.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In FIG. 1, I is a flat grooved tube in which a plurality of grooves A are formed on the inner peripheral surface, and this flat grooved tube I has a thickness T of 0.
It is formed of, for example, a steel pipe with a diameter of 2 mm or more and 0.6 mm or less.

In the orthogonal cross section in the direction orthogonal to the axial direction, the flat grooved tube I is formed such that the vertical dimension H, which is the dimension between the inner peripheral surfaces in the short dimension direction, is 1 mm or more and 5 mm or less,
The horizontal dimension W, which is the dimension between the inner circumferential surfaces in the long direction, is formed to be 3 mm or more and 50 mm or less, and the horizontal aspect ratio (W/H) (width/vertical), which is the ratio of the horizontal dimension W to the vertical dimension H. are formed to be 3 or more. Further, iA is formed in a spiral shape extending at an angle of 0° or more and 30° or less with respect to the axial direction of the flat grooved tube 1. As shown in FIG. 2, this groove A has a width U of the bottom wall A+ of the groove A (dimension between both side edges) of 0.1 mm or more in a cross section perpendicular to the extending direction of the groove A. ．．
4 mm or less, side walls A2 rising from both side edges of the bottom wall Al are inclined so as to approach each other as they move away from the bottom wall A+, and the height V of the side walls A2 from the bottom wall A+ is 0.1 mm or more. 0.025 mm or less, and the pitch P between adjacent grooves A is 0.25 mm or more and 0.7 mm.
It is formed below.

The reason why each dimension is defined as above will be explained below.

First, set the thickness T of the flat grooved tube l to 0.2 mm or more and 06 mm.
The reason for forming the following is that if it is less than 0.2 mm, it will not have sufficient strength against the pressure of the heat medium flowing inside, and if it exceeds 0.6 mm, the heat transfer efficiency will decrease. .

The vertical dimension H is 1 mm or more and 5 mm or less.
If it is less than 5 mm, the resistance will increase to the i%E body resistance of the heating medium, and if it exceeds 5 mm, the way the heat will be transferred to the heating medium such as Freon through the 6 parts of the tube will be poor. This is because the heat transfer medium may remain without being evaporated.

The reason why the width-to-vertical ratio (W/H) is set to 3 or more is because the above-mentioned vertical dimension (■) is formed to be 1 mm or more and 5 mm or less, so unless the width-to-vertical ratio (W/H) is set to 3 or more, it will not heat up. This is because the passage resistance of the medium becomes high.

3 has a horizontal dimension W of 3 mm or more and 50 mm or less.
When the vertical dimension H is set to 1 mm,
This is because if the width/vertical cost (W/H) becomes less than 3, the resistance to the passage of the heat medium will increase, and if it exceeds 50 mm, the flow of the heat medium in the lateral dimension W direction will be biased. This is because, as a result, the heat transfer efficiency cannot be improved.

The reason why the width U of the bottom wall A1 of the groove A is set to 0.1 mm or more and 0.4 mm or less is because if the width is within this range, the heat medium will actively penetrate into the groove A due to surface tension, and the heat transfer will be transmitted. This is because thermal efficiency is sufficiently improved. That is, if it is less than 0.1 mm, the width of 'fItA will be too narrow and it will be difficult for the heat medium to enter the groove A, and if it exceeds 0.4 mm, the width of the groove A will be too wide and the heat medium will not be able to penetrate. iRA due to surface tension
This is because the force penetrating the inside becomes smaller.

The reason why the height V of the wall surface A2 of d4A from the bottom wall A1 is set to 01 mm or more and 0.25 mm or less is that 1. This is because if the IA is too shallow, it will no longer contribute to improving heat transfer efficiency, and on the other hand, if it exceeds 0.25 mm, the HA
This is because the increase in heat transfer efficiency slows down as the depth increases.

The reason why the pitch P between the grooves A is formed to be 0.25 mm or less and 0.7 mm or more is because if it is less than 0.25 mm, the grooves A will be too dense and it will be difficult for the heat medium to penetrate into the grooves A, which will reduce the heat transfer efficiency. This is because it will not be possible to sufficiently improve the
This is because if it exceeds m, the interval between the grooves A becomes large, and in this case as well, the heat transfer efficiency cannot be sufficiently improved.

In the flat grooved tube l constructed as described above, the groove A
As the side walls A2 of the grooves move away from the bottom wall At, they become closer to each other, so that the surface area of the peaks formed between the grooves A increases, and the heat medium is separated from the flat grooved tube 1 or the flat grooves attached. The amount of heat transferred from I to the heat medium increases. In other words, heat transfer efficiency is improved.

Moreover, the thickness T of the flat grooved tube 11 is less than 0.2 mm.
．． Formed to be 6 mm or more, and the vertical dimension H is 1 mm or more and 5 mm
The width and aspect ratio (W/H') is 3 or more, the lateral dimension W is 3 mm or more and 50 mm or less, and the dimension Uh between both side edges of the bottom wall A+ of groove A is 01 mm or more. .4 mm or less, the height V of the wall surface A2 from the bottom wall A1 is 0, Imrn or more and 0.25 mm or less, and the pitch P between adjacent grooves A is 0.25 mm or less and 0.7 m.
m or more, heat is efficiently transferred between the heat medium and the flat grooved tube 1.

Therefore, according to the flat grooved tube 1, the heat transfer efficiency can be significantly improved compared to the conventional flat grooved tube.

The flat grooved tube I constructed as described above is manufactured by the flat grooved tube manufacturing apparatus shown in FIGS. 3 to 5.

In these figures, 11 is a pipe to be processed that is supplied for processing the flat grooved pipe l.

This pipe to be processed [l] has a circular cross section with a plurality of grooves B formed on its inner peripheral surface. For example, after forming a plurality of grooves B on the surface of a strip-shaped plate by rolling, etc., it is rolled into a cylindrical shape. It is manufactured continuously by forming it into a shape and welding the joint part.

The diameter of the pipe to be processed 11 is reduced by a drawing die [2] of the flat grooved pipe manufacturing apparatus, and at that time, the diameter-reducing step 11a formed in the pipe to be processed 11 has a diameter F in the drawing direction F of the pipe to be processed 11. A floating plug 13 is locked from the upstream side.

As shown in FIGS. 3 to 5, the floating plug 13 includes a cylindrical main body 14 and a main body 1.
4 (the upstream end in the drawing direction F) is provided with a head 15 coaxially connected via a screw or the like.

The main body 14 has a flat part +4a formed at the axis of the lower end, and an inclined surface 14b having a shape in which the distance between the flat parts increases from each opposing plane of the flat part 14a toward the outer peripheral surface of the main body 14. It is something. Further, on the outer peripheral surface of the main body I4, a planar notch Kl and a notch 2 are formed in a portion along the inclined surface f4b and a portion along the side edge of the flat portion 14a.

On the other hand, the head 15 is formed with a bulging portion 15c whose outer circumferential surface bulges out from a body portion 15a having a diameter slightly larger than the outer circumferential surface of the main body 14 via a tapered surface 15b. The end face of +5c is formed into a spherical shape.

The floating plug 13 is provided so that the tapered surface 15b of the head I5 is engaged with the diameter-reduced step portion 11alZ of the pipe to be processed 11, and the main body 14 extends downstream in the drawing direction F. That is, the position of the flat part 14a of the floating plug 13 is such that the diameter-reducing step part 11a is located on the pipe 11 to be processed.
It is regulated by the position of the drawing die 12 that forms the .

A flat portion 14a of this floating plug 13.

A flattening die 16 is placed at a position corresponding to the inclined portion 14b.
is provided.

The flat processing die 16 is formed such that a drawing surface 16a surrounds the flat portion 14a and the inclined surface 14b of the floating plug 13, and the drawing surface 16a
The wall surface of the pipe to be processed 11 entering the inside is pressed against the inclined surface 14b and the flat portion 14a.

Next, a method for manufacturing the flat grooved W1 using the apparatus configured as described above will be described.

First, the pipe to be processed 11 is inserted into the drawing die 12. Then, a diameter-reducing step 11a is created in the pipe to be processed 11 by the drawing die 12, and the tapered surface 15b of the head 15 of the floating plug 13 is engaged with the inner surface of this diameter-reducing step +1a. Thereby, the floating plug 13 is held in a position regulated by the drawing die 12. On this occasion,
The tops of the ridges between the grooves 8 formed on the inner circumferential surface are crushed by the head 15 of the floating plug 13 and become wider than the base end. That is, the opposing side walls of the groove become closer toward the nape.

Further, the pipe to be processed 11 whose diameter has been reduced by the drawing die 12 passes around the main body 14 of the floating plug 13 and enters into the drawing surface +6a of the flattening die I6. Then, the pipe to be processed 11 moves while being pressed by the drawing surface 16a along the inclined surface +4b of the main body I4 of the floating plug I3 toward the flat portion 14a. For this reason, the tube to be processed 11 after passing through the flattening die 16 has an inner peripheral surface formed in a flat shape that is almost the same as the flat part I4a of the floating plug 13, and accordingly, the outer peripheral surface is also flat and uniform. is formed. At this time, the inner circumferential surface of the tube to be processed 11 is
The peaks between the grooves 8 become wider.

As described above, the flat grooved tube I having the groove A is continuously formed from the tube to be processed II.

According to the above method for manufacturing the flat grooved tube I, the tube to be processed 11 can be processed into a flat shape without holding the inner surface of the tube to be processed II with the flat portion 14a of the floating plug 13. The vertical dimension H between the inner peripheral surfaces in the direction is Inm or more5
A flat grooved tube l having a large aspect ratio of 3 mm or less and a width/height ratio (W/H) of 3 or more can be manufactured without impairing the flatness of the wall surface of the flat part.

Moreover, by simply pressing the inner circumferential surface of the tube II to be processed with the floating plug 13, the side walls A2 that approach each other toward the top can be easily formed.

Further, the flat grooved tube 1 can be manufactured using a simple manufacturing device equipped with a drawing die 12, a floating plug 13, and a flattening die 16.

Moreover, since it can be processed continuously into flat shapes,
A long flat grooved tube 1 can be manufactured extremely quickly and easily.

Also, from the inclined surface 14b of the floating plug 13, the flattened F! Since the tube to be processed 11 is gradually flattened along the line 4a while being compressed, it is possible to reduce the pulling resistance of the tube to be processed 11, and from this point of view as well, the processing can be speeded up. be able to.

In addition, in the above embodiment, the copper flat grooved tube 1 and its manufacturing example were shown, but the flat grooved tube 1 may be formed of other metal tubes such as aluminum tubes. Needless to say.

[Effects of the Invention] As explained above, according to the flat grooved tube of the present invention, the side walls of the grooves A are formed so as to approach each other as they move away from the bottom wall. The surface area of the top of the mountain is larger than before, and the heat transfer efficiency is improved accordingly.

Moreover, the pitch between 1llTA is 0, 25mm to 0
, 7 mm, the heat medium can easily enter into the iA, and from this point of view as well, the heat transfer efficiency is improved compared to the conventional case.

Furthermore, the vertical dimension between the inner peripheral surfaces in the short direction is 1 mm or more and 5 m.
m or less and the width/length is 3 or more, so the 6
Enough heat is transferred to and from the heat medium flowing through the tube, and from this point of view, the heat transfer efficiency is improved compared to conventional tubes.Therefore, compared to conventional flat grooved tubes, heat transfer efficiency is significantly improved. can be done.

Further, according to the above method for manufacturing a flat grooved tube, by compressing the inner peripheral surface of the pipe to be processed by the floating plug, the tops of the ridges between the grooves B are compressively deformed. The width of the top part of the can be made wider than the width of the base end part.

Therefore, side walls that approach each other as they move away from the bottom wall can be easily and quickly formed.

Moreover, since the pipe to be processed is held from the inside by a floating plug and formed into a flat shape, the vertical dimension between the inner peripheral surfaces in the short direction is 1 mm or more and 5 mm or less, and the horizontal/vertical ratio is 3 or more. Even in a large state, a flat grooved tube with good flatness of the wall surface of the flat part can be easily manufactured.

Moreover, since a flat grooved tube can be manufactured from a tube to be processed by continuously drawing the tube to be processed, a long flat grooved tube can be manufactured extremely quickly and easily.

[Brief explanation of the drawing]

1 to 5 are views showing one embodiment of the present invention, in which FIG. 1 is a perspective view of a flat grooved tube showing a cross section perpendicular to the axis, and FIG. Figure 3 is an enlarged view showing the main part (■); Figure 3 is a sectional view showing the flat grooved pipe manufacturing equipment;
The figure is a view of the floating plug in FIG. 3 taken along the line ■--■ in FIG. 4, and FIG. B... Groove B1 F... Pulling direction, H... Vertical dimension, B... Axial direction, W... Horizontal dimension, W/H ...Aspect ratio (width/height). ...Flat grooved tube l...To be processed pipe, Ia...Reduced diameter step, 2...Drawing die, 3...Floating Plug 4...Body, 4a...Flat part, 4b...Slanted surface, 5...Head, 6...Flat processing die, A... ...Groove A, AI...Bottom wall, A2...Side wall,

Claims (2)

[Claims] (1) In a flat grooved tube in which a plurality of grooves A extending in a direction intersecting an orthogonal cross section perpendicular to the axis are formed on the inner circumferential surface, the dimension between the inner circumferential surfaces in the short dimension direction in the orthogonal cross section is A certain vertical dimension is formed to be 1 mm or more and 5 mm or less, and the horizontal/vertical ratio, which is the ratio of the horizontal dimension, which is the dimension between the inner peripheral surfaces in the longitudinal direction of the orthogonal cross section, and the vertical dimension, is 3 or more. The groove A is formed such that each side wall rising from both side edges of the bottom wall approaches each other as the distance from the bottom wall increases, and the pitch between adjacent grooves A is A flat grooved tube characterized in that it is formed to have a diameter of 0.25 mm or more and 0.7 mm or less. (2) A cylindrical workpiece tube with a plurality of grooves B formed on its inner peripheral surface is reduced in diameter with a drawing die, and one end is held in the reduced diameter part of the workpiece tube whose diameter has been reduced with the drawing die. The pipe to be processed is pressed by a flattening die against the flat part formed at the other end of the floating plug, the other end of which extends downstream in the drawing direction, thereby flattening the pipe to be processed. It is characterized by forming the groove into a shape, and compressing and plastically deforming the top of the mountain between the grooves B on the inner circumferential surface to make the width of the top of the mountain wider than the width of the base end. A method for manufacturing a flat grooved tube.