JP2001116482A - Fin material heat transfer tube, its manufacturing method, finned heat-transfer tube and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat transfer performance of a heat transfer tube by increasing the heating area of the tube as much as possible without increasing the resistance of an external fluid. SOLUTION: A finned heat transfer tube is constituted by fixing a belt-like fin material composed of a tip section having notches formed in the width direction of the material and a root section which is the continuous portion of the fin material having a uniform thickness and the tip section is formed in such a way that its tip part has a broader width and a thinner thickness than its root portion has and such a cross section heat both side sections are thinner than the central section. A method for manufacturing the fin material includes a step of curving the fin material by rolling the tip section of the material, a serrating step for forming cuts into the tip section and, at the same time, inclining each tip section, and a curve correcting working of correcting the curved shape of the fin material by rolling the root section of the material so that adjacent tip sections may overlap each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fin material for a heat transfer tube, a method for manufacturing the same, and a heat transfer tube with a fin and a method for manufacturing the same. In particular, a fin capable of increasing the amount of heat exchange with a small number of heat transfer tubes. This is a technology related to heat transfer tubes.

[0002]

2. Description of the Related Art Heat transfer tubes typified by superheater tubes and reheater tubes of boiler devices have conventionally been provided with fins on the surface thereof in order to increase the heat transfer area. Have been.

[0003] When the extra-pipe fluid flowing around the fins provided in the heat transfer tube is higher in temperature than the intra-pipe fluid, the heat of the extra-pipe fluid is transmitted to the fins, transmitted through the fin material, and passed through the pipe wall to the intra-pipe fluid. Convey. Therefore, in order to improve the heat transfer performance of the heat transfer tube, it is effective to improve the heat transfer coefficient and surface area of the fin surface, the heat transfer coefficient and passage cross-sectional area of the fin, and the heat transfer coefficient and surface area of the inner surface of the tube. . Incidentally, since the heat transfer amount has the following relationship, the heat transfer amount can be increased by increasing the heat transfer amount Q = heat transfer area A × heat transfer coefficient × temperature difference ΔT and / or the heat transfer coefficient.

[0004] In particular, when the fluid outside the tube is a gas, the heat transfer coefficient is small. Therefore, increasing the surface area outside the tube by fins is effective for improving the heat transfer performance.

[0005] The shape of the fins formed on the surface of the heat transfer tube may be, for example, a solid fin obtained by continuously winding a band steel fin material around the surface of the heat transfer tube, or a saw-tooth cut into the band fin material. Serrated fins wound around the surface of the heat tube are exemplified.

FIG. 18 is a partial cross-sectional view perpendicular to the longitudinal direction of a heat transfer tube having solid fins in which fin materials are not cut, and FIG. 19 is a longitudinal sectional view of the heat transfer tube. FIG. In FIGS. 18 and 19, solid fins 9 made of a steel strip without cutting are wound around the heat transfer tube 1 and fixed. Since the solid fins 9 are formed by forcibly stretching the uncut steel strip and winding it around the heat transfer tube 1 and fixing it by, for example, welding, the winding conditions are limited (especially,
On the outer peripheral side of the solid fin, it is forcibly stretched at the time of winding, or wrinkles are generated on the inner peripheral side of the solid fin, so that pressure welding is difficult), and the winding speed and the fin shape at the time of manufacturing are limited. In addition, such a solid fin has a slightly thinner wall thickness than the root portion due to the extension of the tip portion of the fin, but is not intentionally made thinner.

FIG. 20 is a partial cross-sectional view of a conventional heat transfer tube having serrated fins, which is perpendicular to the longitudinal direction. FIG. 21 is an enlarged view of the fin tip. In the figure, there is shown a serrated fin 7 having a plurality of fin tips (hereinafter, also simply referred to as tips) 8 to which a fin material having a sawtooth cut is spirally wound and fixed on the surface of the heat transfer tube 1. I have. This serrated fin 7
Are twist serrated fins in which the fin tips 8 are respectively twisted in predetermined directions to disturb the gas flow flowing on the surface of the heat transfer tube and generate vortices to further improve the heat transfer performance. The width _Wfo and the width _ft of the tip portion are substantially the same. Further, since the fin material is cut, the cross-sectional thickness of each chip is almost the same at the root portion and the tip portion.

[0008] Serrated fins such as such twisted serrated fins, when cut into the fin material, have less deformation during winding,
The winding speed during processing can be increased as compared with the solid fin. In addition, the heat transfer area of serrated fins such as twisted serrated fins increases and decreases according to the increase in the area of the cut surface of the cut chip and the decrease in the area of the gap between the chips. Since the base of the chip extends because it is wrapped around the surface, it slightly increases or decreases compared to the solid fins depending on the manufacturing method, but the heat transfer performance is equal to or higher than that of the solid fins.

However, the above-mentioned conventional solid fins and serrated fins are the original purpose of the fin,
Although it cannot be said that the shape is sufficient to increase the heat transfer area, improvement in heat transfer performance based on turbulence in gas flow can be expected,
There is still room for improvement in improving the heat transfer performance based on the increase in the heat transfer area.

In order to further improve the heat transfer performance of the finned heat transfer tube, the fin density in the length direction of the heat transfer tube is increased, or the heat transfer area outside the tube is increased by increasing the fin height. However, such a method is the basic idea of adopting an enlarged heat transfer surface,
This is a method that has been studied and adopted in the past.For example, when the height is increased, the fin efficiency decreases and the outer diameter increases, so it is necessary to increase the pitch of the heat transfer tubes. The portion is easily deformed, and there is a problem in processing speed, fin adhesion degree, and the like.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to increase the heat transfer area, which is the original object of the fin, as much as possible without increasing the resistance of the extravascular fluid. Accordingly, it is an object of the present invention to provide a heat transfer tube fin material and a method of manufacturing the same, and a finned heat transfer tube and a method of manufacturing the same, which can further improve the heat transfer performance.

[0012]

In order to solve the above problems, the present invention mainly employs the following configuration.

A strip-shaped fin material comprising a chip portion cut in the longitudinal width direction of the strip-shaped fin material and a root portion which is a continuous portion having a uniform thickness of the strip-shaped fin material is fixed to the surface of the heat transfer tube. A heat transfer tube with fins, wherein the tip portion has a tip portion in the vertical width direction that is wider and thinner than a root portion on the root portion side.

Further, a band-like fin material comprising a chip portion cut in the longitudinal width direction of the band-like fin material and a root portion which is a continuous portion having a uniform thickness of the band-like fin material is provided.
A finned heat transfer tube fixed to a surface of the heat transfer tube, wherein the tip portion has a tip portion in the vertical width direction that is wider and thinner than a root portion on the root portion side. The cross-sectional shape of the tip portion is a finned heat transfer tube in which the central portion in the lateral width direction of the fin material is thick and the both sides of the central portion are thin.

Further, in the heat transfer tube with fins, a lateral width Wft of a tip portion of the tip portion is represented by the following equation.

Wft / Wfo> (Dt + 2Hf) / (Dt + 2hr) Here, Wfo: lateral width of the root portion of the chip portion Dt: outer diameter of the heat transfer tube Hf: total height of the fin hr: height of the root portion.

Further, in the heat transfer tube with fins, the heat transfer tube with fins may be twisted by twisting the tip portion at a predetermined angle with respect to the root portion.

A band-shaped fin material comprising a chip portion cut in the longitudinal direction of the band-shaped fin material and a root portion which is a continuous portion having a uniform thickness of the band-shaped fin material, A band-shaped fin material in which a tip portion in the longitudinal width direction has a wider width and a smaller thickness than a root portion on the root portion side, and a tip portion of an adjacent chip portion overlaps. .

Rolling the one side portion of the band-shaped fin material to bend the fin material; cutting a tip portion, which is the rolled one side portion, toward the curved center portion; A serration processing step of inclining each chip portion, and a bending correction step of rolling a root portion, which is the other side portion of the band-shaped fin material, to correct a curved shape of the fin material, Production method.

Rolling the one side portion of the band-shaped fin material to bend the fin material; cutting a tip portion, which is the rolled one side portion, toward the curved center portion; A serration process in which each tip portion is inclined, and a straightening process in which a root portion, which is the other side portion of the band-shaped fin material, is rolled to correct the curved shape of the fin material so that adjacent tip portions overlap each other. In the process, the overlapping tip portion is rolled, and the extension of the tip portion in the longitudinal direction of the fin material is regulated so that the length of the tip portion in the longitudinal direction is extended without changing the length of the tip portion. And a method of manufacturing a fin material for a heat transfer tube.

The band-shaped fin material is wound on a fin take-up reel, the band-shaped fin material is sent out from the take-up reel to the surface of the heat transfer tube, and a side edge of a root portion of the band-shaped fin material is connected to the heat transfer tube. A method for manufacturing a finned heat transfer tube in which a band-shaped fin material is spirally fixed to a surface of the heat transfer tube by continuous welding to the surface.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A finned heat transfer tube according to a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view perpendicular to the length direction of the heat transfer tube according to the first embodiment of the present invention, FIG. 2 is a partially enlarged view of a part of FIG. 1, and FIG. FIG. 4 is a schematic diagram illustrating a case where a finned heat transfer tube according to the embodiment is installed in a gas flue; FIG. 4 is a detailed view illustrating a wide portion of the fin tip according to the first embodiment; It is explanatory drawing which shows the cross section of a fin tip. FIG. 6 is an explanatory view for explaining the principle of the first embodiment of the present invention, and FIG. 7 is a view showing various specific shapes and heat transfer area ratios of the fin chips in FIG.

In the present invention, the tip portion of the fin tip refers to a radially extending portion formed of a fin material having a sawtooth cut, and the root portion refers to a root portion at which the fin tip extends radially. No, it refers to a continuous strip that is common to each fin tip without being separated.
However, in the present invention, the root portion corresponding to the tip portion of each fin tip is referred to as the fin tip root portion or simply the root portion for convenience. The fin is fixed to the surface of the heat transfer tube by, for example, continuous resistance welding of this root portion. Then, a fin tip is formed by the tip part and the root part. The height of the root is usually 4-5mm
It is.

The finned heat transfer tube is formed by continuously winding a cut fin material around the heat transfer tube 1 in a helical manner and fixing the fin material by continuous resistance welding, for example, to a thickness of 1.2 mm.
Flat serrated fins having a large number of fin tips having a width of 4 mm and a height of 7.7 mm (see FIGS. 1 and 2), and the tip portions 4 of the fin tips 3 of the flat serrated fins are respectively twisted in predetermined directions. After the tip portion surface is inclined by, for example, 20 degrees with respect to the root portion surface, the tip portion 4 is pressed to make the thickness of the tip portion 4 thinner toward the front end portion, and at the same time, to increase the width toward the front end portion ( 4 and 5). The tip end has a thickness of, for example, 0.6 mm and a width of, for example, 8 mm (see FIG. 7).

In FIG. 3 and FIG.
Is wider at the tip end W _ft than at the base width W _fo . Further, in FIG. 5, the thickness T _t of the distal end portion of the fin chip 2 thinner than the thickness T _o of the base portion (root portion), is gradually thinner becomes the tip portion from the base portion. The height H _f fin chip 2 is represented as the sum of the height h _r and height h _c of the tip portion of the root portion.

The finned heat transfer tube 1 having such a configuration is as follows.
As shown in FIG. 3, for example, it is disposed in a flue in which the flue gas 6 flows, and is used as, for example, a superheater tube for recovering the calorific value of the flue gas.

According to this embodiment, the surface of the heat transfer tube 1
Continuously spirally wind the fin material with the cut,
For example, serrated fins are fixed by continuous resistance welding, and the tip portion 4 of the fin tip 3 of the serrated fin is twisted in a predetermined direction with respect to the root portion 5 to be inclined. By making the tip of the part 4 thinner and wider at the tip,
Approximately 15-20% heat transfer area while suppressing increase in material weight
Can be increased. Therefore, the heat transfer performance is improved,
The required number of heat transfer tubes can be reduced by 10 to 15%.

Since the size of the entire heat transfer device is mainly determined by the number of heat transfer tubes, the present embodiment in which the number of heat transfer tubes can be reduced makes the heat transfer device more compact and has a greater overall economic effect. Become.

The first embodiment of the present invention is provided with the configuration as described above, and has the following origin, principle, function and operation as described below.

Considering the relationship between the shape of the fins provided on the surface of the heat transfer tube and the heat transfer area and the like, an experiment shows that, for solid fins, the fin height increases when the fins are pressed and extended, but the heat transfer coefficient increases. This does not mean that the fin efficiency decreases, but the heat transfer performance and economic efficiency are almost the same as when a wide fin material is wound from the beginning at a certain height or higher. In the case of the serrated fin, since the tip width is smaller than the height of the tip portion, the tip portion can be easily extended in the width and height directions by pressing the tip portion, thereby increasing the heat transfer area and increasing the width. It is also possible to extend only in the direction, and twist or bend each tip of the serrated fin so that each tip It comes into contact with, it is possible to increase the heat transfer coefficient to obtain knowledge.

As a result, in the heat transfer tube with fins in which a large number of fin chips are formed in a sawtooth shape on the surface of the heat transfer tube, the tip portion of the fin tip is pressed or rolled so that the tip portion is thinner and wider. As a result, it has been found that the heat transfer area is significantly increased and the heat transfer performance is improved as compared with a heat transfer tube having fins of different shapes formed using the same fin material.

FIG. 6 is an explanatory view showing the principle of the present invention. A flat serrated fin having a fin height of 12.7 mm and a fin thickness of 1.2 mm is used. Is constant and constant, and the average thickness Tt / root of the tip portion of the tip portion when the tip portion is rolled so as to gradually decrease its thickness toward the tip portion and the width thereof is increased toward the tip portion FIG. 9 shows a change in a heat transfer area ratio and a change in a tip tip width / root width ratio with respect to a change in the part thickness To.

FIG. 7A shows that the outer diameter of the heat transfer tube is 3 mm.
For three heat transfer tubes of 1.8, 38.1, and 50.8 mm, the dimensions of each part in each fin portion and (D
3 shows basic data on the relationship of (t + 2Hf) / (Dt + 2hf). And (2) of FIG.
FIG. 6 shows the relationship between the thickness (T _t ) of the tip portion of the fin tip and the heat transfer area ratio and the relationship between these and the width W _{ft of the} tip portion of the fin tip, It shows the ratio to the thickness of the part (root part). At this time, the height remains unchanged.

Here, the rolling of the tip portion of the fin tip is intended to extend only in the width direction without changing the height dimension. However, in the actual rolling operation, the tip portion in the height direction is rolled. The dimensions may be slightly increased in actual processing, and this case is naturally included within the scope of the concept of the present invention.

The heat transfer area ratio is shown as a ratio of the heat transfer area of the flat serrated fin after rolling to the heat transfer area of the flat serrated fin in which the tip portion is not rolled.

6 and 7, by gradually reducing the thickness of the tip portion of the fin tip, the width W _ft and the heat transfer area ratio of the tip portion gradually increase.
When the tip portion is rolled to a thickness of 0.6 mm, that is, half the thickness of the root portion (root portion), W _ft at the tip portion becomes equal to the root portion (root portion). Width W
It can be seen that the ratio becomes twice as large as the _fo , and the heat transfer area ratio increases by about 20% as the fin surface increases.

In the present invention, if the tip of the fin tip is made too thin, for example, by rolling,
A contact portion with a support attached for preventing vibration may become small, resulting in insufficient strength. Therefore, the thickness of the tip of the fin tip is thinner than the thickness of the fin material,
It is preferably 0.2 mm or more. More preferably, the thickness of the fin material, that is, the ratio of the thickness of the fin tip (tip tip) to the thickness of the fin root (root) is 0.67 (as can be seen from FIG. 7, the heat transfer area ratio is less). 10%) and the thickness of the tip of the fin tip is 0.2 mm or more.

In the present invention, when the tip portion of the fin chip is rolled, it can be extended in the height direction of the chip, but if it is extended in the height direction, the connection with the support and the like will all be changed. Since the vibration preventing support is in contact with the tip of the tip portion, it is necessary to change the dimension and shape of the support when the tip height changes), and it is more preferable to extend only in the width direction of the fin tip.

In the present invention, it is preferable that the fin tips provided in a sawtooth shape are each twisted in a predetermined direction so that the tip portion surface is inclined by a predetermined angle with respect to the root portion surface. The inclination angle (twist angle) is 15 to 35 degrees, preferably 20 to 30 degrees. If the inclination angle is too large, the flow of the extravascular fluid is hindered due to the relationship with the adjacent fin tip, and the heat transfer performance is reduced. On the other hand, if the inclination angle is too small, the increase in the heat transfer performance becomes insufficient.

Next, a fin material and a finned heat transfer tube according to another configuration example of the first embodiment of the present invention will be described. The fin material and the finned heat transfer tube according to the above configuration example have a tip portion of the tip portion with respect to the lateral width Wfo of the root portion of the tip portion with respect to the heat transfer tube outer diameter Dt, the fin material total height Hf, and the root portion height hr. Is a fin material represented by the following equation. The dimensional relationship described above is shown in FIG.
And the display shown in FIG.

Wft / Wfo> (Dt + 2Hf) / (Dt + 2hr) The above equation shows a condition in which, when a fin material is wound around a heat transfer tube, the tip portions of adjacent fin materials overlap with no gap. That is, the right side of the inequality sign indicates the ratio of the circumferential length of the tip portion to the circumferential length of the root portion of the finned heat transfer tube. This indicates that the ratio of the width of the tip portion to the width is large, that is, that the adjacent chip portions overlap. Under the conditions of the above formula, the heat transfer tube with serrated fins with the fin tip twisted,
The fin heat transfer area can be larger than that of a conventional heat transfer tube with solid fins. Here, the manufacturing method of fixing the fin material to the heat transfer tube and then twisting the fin material or fixing the twisted fin material to the heat transfer tube is described in the fourth and fifth embodiments described later. As can be seen, either one is good.

Next, a finned heat transfer tube according to a second embodiment of the present invention will be described below with reference to FIGS. FIG. 8 is a sectional view perpendicular to the longitudinal direction of the finned heat transfer tube according to the second embodiment of the present invention, and FIG.
It is sectional drawing of the fin chip of embodiment.

This finned heat transfer tube has a flat serrated fin in which a cut fin material is continuously wound spirally around the heat transfer tube 1 and fixed, that is, in the first embodiment of the present invention. , Fin tip 3
In a state where it is flat without twisting the tip part 4 of
The tip portion 4 is pressed, and the tip portion is made thinner and wider at its tip. The tip portion 4 and the root portion 5 of the fin tip 3 are on the same plane. In the present embodiment, the performance is not much different from that of the pressed solid fin, but the deformation of the root of the fin is small and high-speed winding is possible.

Next, a finned heat transfer tube according to a third embodiment of the present invention will be described below with reference to FIGS. FIG. 10 is a sectional view perpendicular to the length direction of the finned heat transfer tube according to the third embodiment of the present invention.
1 is a cross-sectional view of a fin tip according to a third embodiment.

The fins provided in the heat transfer tube according to the third embodiment of the present invention are flat serrated in which the tip portion 4 of each fin tip 3 is rolled to reduce the thickness toward the tip and to increase the width. The fin tip 3 of the fin
The tip 4 is bent in the opposite direction with respect to the root 5 every other central axis of the tip 4 to provide a step. The fin shape in this embodiment has an intermediate characteristic between the flat serrated fin and the twist serrated fin in which the tip portion 4 is rolled, and the heat transfer area and heat transfer by rolling the tip portion 4 of the fin tip 3. Coefficients can be increased together.

Next, a fin material for a heat transfer tube and a method for manufacturing the same, and a heat transfer tube with fins and a method for manufacturing the same according to a fourth embodiment of the present invention will be described with reference to FIGS. 12 and 14 to 17.
This will be described below. FIG. 12 is a diagram illustrating an outline of a method of manufacturing a fin material for a heat transfer tube.

In FIG. 12, a long thin plate, for example, a fin material having a thickness of 1.2 mm and a vertical width of 12.7 mm is prepared. The hatched portion in the drawing corresponds to the tip portion of the fin chip, and the blank portion corresponds to the root portion. For example, the vertical width of the tip portion is 7.7 mm and the vertical width of the root portion is 5.0 mm. Next, as shown in (1) of FIG. 12, a portion corresponding to the tip portion is appropriately rolled as described later (FIG. 14).
), The fin material is stretched at the rolled portion and naturally assumes a curved shape.

Subsequently, as shown in FIG. 12 (2), a serrated process is performed on the curved fin material to cut a portion corresponding to the chip portion to form a cut surface. More specifically, a cutting surface is formed by pressing a portion corresponding to the chip portion sequentially with the blade of a fixedly installed cutter. The fin material is moved each time a cut surface is formed, and a cut surface is formed by press working each time to form a tip portion and a root portion. In this step, a plurality of cut surfaces can be formed simultaneously by providing a plurality of cutter blades for forming the cut surface.

In forming the cut surface, the cutting direction is the direction toward the center point of the curved shape of the fin material. Accordingly, the length (lateral width) of the root portion of the cut tip portion in contact with the root portion and the tip portion of the tip in the thin plate longitudinal direction is longer than the root portion, that is, the tip portion has a wider shape. In other words, it has a tapered shape, has a divergent configuration in which the width is longer at the tip portion than at the root portion, and has a larger area than the initially prepared long thin plate.

Further, when a special cutting mechanism (see FIG. 15) described later is used for cutting by the cutter blade, the tip portion is twisted (twisted) together with the cutting, and is inclined with respect to the surface of the root portion. , Forming twisted serrated fins.

Subsequently, as shown in (3) of FIG. 12, a rolling process is performed on a long thin sheet having a serrated shape, thereby correcting the curved shape to obtain a straight shape. The fin material according to the embodiment is formed. In the step of correcting the curved shape, the root portion of the fin tip can be rolled and expanded to have a linear shape.
In addition to the straightening of the root portion by rolling, a side edge of the curved fin material can be forcibly moved along a linear guide to form a straight line (see FIG. 17). At the time of this correction, the tip portion has a twisted shape as described above. Therefore, after the correction, the tip portion of the tip has an overlapping shape as shown in the drawing. The fin material wound around the heat transfer tube is an article which is a sales unit by itself. If the fin material is in a curved shape in terms of handling and transporting the fin material, inconvenience occurs.

As described above, the fin material obtained by deforming the curved shape into a linear shape may be stored by being wound around a winding drum with the flat surface of the thin plate as an overlapping surface.
It may be fed online in the step of winding the fin material around the heat transfer tube.

When the fin material is wound around the heat transfer tube, the side edge of the root portion of the fin tip is brought into contact with the outer peripheral surface of the heat transfer tube and wound, and the heat transfer tube and the root portion immediately adjacent to the winding contact are welded, respectively. As the electrode, for example, the heat transfer tube and the root side edge are continuously connected by high frequency resistance welding.

Next, the features of the present embodiment will be described by exemplifying the specific dimensional structure of the fin material. The curved fin material subjected to the serration process has a root portion having a thickness of 1.2 mm, a root portion having a vertical width of 5.0 mm, and a tip portion having a vertical width of 7.7 mm. When the width of the root portion of the tip portion of the fin tip is 4.0 mm pitch and the radius of curvature of the inner peripheral edge of the curved root portion is 80 mm, the relationship between the radius of curvature and the vertical width of the fin material is obtained. The width of the tip of the tip is 4.4 mm.

That is, in the serrate processing step, the tip portion has a structure in which the width of the root portion is 4.0 mm and the width of the tip portion is 4.4 mm. Since the extension of the vertical width of the chip portion is regulated, the thickness of the tip portion of the chip portion is changed from 1.2 mm to 1.1 mm, assuming that the lateral width is proportional to the thickness. Referring to FIG. 6, when the thickness is 1.1 mm, the heat transfer area ratio is about 1.
03, which leads to approximately 3% improvement in heat transfer performance.

Next, various mechanisms used in the fin material manufacturing method will be described. FIG. 14 shows a rolling mechanism used in a rolling process of a portion corresponding to a tip portion of a fin tip and a fin material bending correcting process after a serrate working process. As shown in FIG. 14 (1), there is also a configuration example (parallel roller / axis tilting method) in which two cylindrical rollers are used, and their center axes are non-parallel, and the edge side of the rolling portion is rolled. There is also a configuration example (conical roller / axis parallel system) in which the two rolls are rolled on the edge side of the rolling portion using two taper rollers with their central axes parallel.

FIG. 15 shows a mechanism for cutting and twisting the tip portion in the serrate processing step. A cut surface is formed on a long thin plate fed and moved by a fixed cutter base and a vertically moving cutter blade. At this time, the cutter blade forms an inclined pressing surface that presses the tip portion so that the cut tip portion has a twist shape. The cutter table also has an inclined surface facing the inclined pressing surface of the cutter blade. By using the illustrated mechanism, a cut surface is formed in a portion corresponding to the tip portion of the long thin plate, and the cut tip portion is pressed to form an angle different from the root portion plane, thereby forming a twist shape. By employing such a mechanism, cutting and twisting at the tip portion can be performed substantially simultaneously.

Next, a fin material for a heat transfer tube according to a fifth embodiment of the present invention and a method for manufacturing the same, and a heat transfer tube with fins and a method for manufacturing the same will be described below with reference to FIGS. 13, 16 and 17. I do. FIG. 13 is a diagram showing a final step in the method for manufacturing a fin material for a heat transfer tube according to the fifth embodiment, and FIG. 16 is an example of a tip part rolling mechanism (pressing method) used in the steps of the fifth embodiment. It is a figure which shows the example of a rolling).

In the above-described fourth embodiment of the present invention, the fin tips formed through the fin material bending correction step can improve the heat transfer performance by approximately 3% as an example, but can improve the heat transfer performance by approximately 10%. In order to improve the heat transfer performance beyond the above, it is necessary to increase the heat transfer area ratio by further increasing the lateral width of the tip portion of the chip portion.

For this reason, in the fifth embodiment, a tip part rolling step is further added to the fin material after the curvature correcting step of the fourth embodiment. As shown in FIG. 16, the fin material having a tip end having a width W1 is subjected to a rolling process, for example, by pressing the tip portion using press working, or by fins between the rolling rollers. By passing the material through, the tip portion is further expanded and the tip portion is set to W2 (> W1).

At this time, in order not to change the vertical width of the chip, rolling may be performed with a vertical regulating member (not shown) provided. In the step of rolling the tip portion, the tip portion is rolled so as to increase the horizontal width while regulating the vertical width, but this rolling hardly causes the entire fin material to bend. In other words, the rolling force applied to the tip portion is largely absorbed at the cut portion of the tip portion, and extends in the lateral width, and hardly acts as a force for bending the root portion.

As can be seen from FIGS. 13A and 13B, the overlapping portion of the adjacent chip portion is particularly forcibly rolled, so that the overlapping portion is thinner than the central portion. . The strength of the chip portion is ensured by the thickness structure of the central portion. In addition, the thickness of the central portion and the thin structure at both sides of the tip portion cause an effect of disturbing the flow of the extravascular fluid, thereby increasing the heat transfer coefficient.

The fin material that has passed through the tip rolling step is:
The thin plate may be wound around a winding drum and stored as an overlapping surface, or may be fed online in the step of winding the fin material around the heat transfer tube.

Illustrating a specific dimensional structure of the fin material in the tip rolling step, the root width of the tip part after the straightening step, which is a preceding step of the step, is 4.0 mm.
The tip width of the tip was 4.4 mm.
The tip part width became approximately 6.0 mm with respect to the root part width of 4.0 mm by the tip part rolling process. Referring to FIG. 6 and FIG. 7, the heat transfer area ratio is 1.1, which means that the heat transfer performance is improved by approximately 10%.

The fin material having undergone the tip rolling step shown in FIG. 16 is continuously spirally wound around the heat transfer tube by high-frequency resistance welding in the same manner as described above.

FIG. 17 is a view showing a series of steps for manufacturing a fin material having a wide and thin tip portion according to the embodiment of the present invention. A series of manufacturing steps shown in FIG. 17 are performed by sequentially arranging a bending step by rolling, a serrate processing step, a bending correction step, and a tip part rolling step shown in FIGS. 12 and 13 to produce a desired fin material. It is shown schematically.

The linear fin material is moved in the direction of the arrow, and the pressing portion of the primary rolling mechanism is moved in the direction of the arrow with respect to the receiving portion to roll and curve the fin material. The chip is cut (cut) and the tip is twisted. Subsequently, by passing the fin material through a curvature straightening guide, the curved fin material is forcibly straightened along the linear shape of the guide, and the fin material is straightened. Further, the pressing portion of the secondary rolling mechanism is moved in the direction of the arrow with respect to the receiving portion to roll the overlapping chip portion, thereby further increasing the dimension of the chip portion in the lateral width direction. By passing the fin material through such a manufacturing process, a fin material having a laterally wide and thin tip portion can be continuously manufactured.

[0068]

According to the present invention, the heat transfer area can be increased without increasing the weight of the fin material by increasing the thickness and width of the tip portion of the fin material at the tip portion. The heat transfer performance can be improved.

Therefore, since the number of heat transfer tubes can be relatively reduced, the weight of the heat transfer device can be reduced, and the economy due to the compactness can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view perpendicular to the length direction of a heat transfer tube according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view in which a part of FIG. 1 is enlarged.

FIG. 3 is a schematic diagram when a finned heat transfer tube according to the first embodiment is installed in a gas flue.

FIG. 4 is a detailed view showing a wide portion of the fin tip according to the first embodiment.

FIG. 5 is an explanatory view showing a cross section of the fin tip of FIG. 4;

FIG. 6 is an explanatory diagram illustrating the principle of the first embodiment of the present invention.

FIG. 7 is a view showing various specific shapes and heat transfer area ratios of the fin tip portion in FIG. 6;

FIG. 8 is a cross-sectional view perpendicular to the length direction of a finned heat transfer tube according to a second embodiment of the present invention.

FIG. 9 is a sectional view of a fin tip according to a second embodiment.

FIG. 10 is a cross-sectional view perpendicular to the length direction of a finned heat transfer tube according to a third embodiment of the present invention.

FIG. 11 is a cross-sectional view of a fin tip according to a third embodiment.

FIG. 12 is a diagram schematically illustrating a method of manufacturing a fin material for a heat transfer tube according to a fourth embodiment of the present invention.

FIG. 13 is a view showing a final step in the method for manufacturing a fin material for a heat transfer tube according to the fifth embodiment of the present invention.

FIG. 14 is a view illustrating a rolling mechanism used in a rolling step of a portion corresponding to a tip portion of a fin tip according to a fourth embodiment, and a fin material bending correction step after a serrate processing step.

FIG. 15 is a view showing a mechanism for forming a twist shape of a tip part in a serrate processing step of the fourth embodiment.

FIG. 16 is a diagram showing an example of a tip part rolling mechanism used in a process according to the fifth embodiment.

FIG. 17 is a view showing a series of steps for manufacturing a fin material having a wide and thin tip portion according to the embodiment of the present invention.

FIG. 18 is a partial sectional view perpendicular to a length method of a heat transfer tube having a solid fin according to the related art.

FIG. 19 is a partial cross-sectional view along a length method of a heat transfer tube having a solid fin according to the related art.

FIG. 20 is a partial cross-sectional view perpendicular to a length method of a heat transfer tube having twisted serrated fins in the prior art.

FIG. 21 is a partial cross-sectional view of a heat transfer tube having twisted serrated fins according to the prior art, taken along a length method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat transfer tube 2 Serrated fin 3 Fin tip 4 Tip part 5 Root part 6 Exhaust gas 7 Serrated fin 8 Fin tip 9 Solid fin

Continued on the front page (72) Inventor Hirotaka Shirai 6-9 Takara-cho, Kure City, Hiroshima Prefecture Inside the Babcock Hitachi Kure Factory (72) Inventor Kikumoto 6-9 Takara-cho Kure City, Hiroshima Prefecture Babcock Hitachi Kure Factory Inside

Claims (10)

[Claims] 1. A band-shaped fin material comprising a chip portion cut in the longitudinal direction of the band-shaped fin material and a root portion which is a continuous portion having a uniform thickness of the band-shaped fin material is provided on the surface of the heat transfer tube. A heat transfer tube with fins fixed, wherein the tip portion has a tip portion in the vertical width direction that is wider and thinner in thickness than a root portion on the root portion side. Heat transfer tube with fins. 2. A heat transfer tube surface is provided with a band-shaped fin material including a chip portion cut in a longitudinal direction of the band-shaped fin material and a root portion which is a continuous portion having a uniform thickness of the band-shaped fin material. The heat transfer tube with fins fixed, wherein the tip portion has a tip end portion in the vertical width direction that is wider and thinner in thickness than a root portion on the root portion side, The heat transfer tube with fins is characterized in that the cross-sectional shape of the heat transfer tube with fins is characterized in that the central part in the width direction of the fin material is thick and thin on both sides of the central part. 3. The heat transfer tube with fins according to claim 1, wherein the lateral width Wft of the tip portion of the tip portion is represented by the following equation. Wft / Wfo> (Dt + 2Hf) / (Dt + 2hr) where, Wfo: lateral width of the root portion of the chip portion Dt: outer diameter of the heat transfer tube Hf: total height of the fin hr: height of the root portion 4. The heat transfer tube with fins according to claim 1, wherein the tip portion is twisted so as to be inclined at a predetermined angle with respect to the root portion to form a twist shape. Heat transfer tubes with fins. 5. The finned heat transfer tube according to claim 4, wherein the tip portions of adjacent chip portions overlap each other with a gap when viewed from the heat transfer tube length direction. Heat tube. 6. A band-shaped fin material comprising a chip portion cut in the longitudinal width direction of the band-shaped fin material and a root portion which is a continuous portion having a uniform thickness of the band-shaped fin material, wherein the chip is provided. The tip is characterized in that the tip portion in the vertical width direction has a wider width and a smaller thickness than the root portion on the root portion side, and the tip portions of adjacent chip portions overlap each other. Band-shaped fin material. 7. A step of rolling one side portion of the strip-shaped fin material to bend the fin material, and cutting a tip portion, which is the rolled one side portion, toward the curved center portion. A transmission process characterized by: a serrate processing step of inclining each tip portion; and a bending correction step of rolling a root portion, which is the other side portion of the band-shaped fin material, to correct a curved shape of the fin material. A method for manufacturing a fin material for a heat tube. 8. A step of rolling one side portion of the band-shaped fin material to bend the fin material, and cutting a tip portion, which is one side portion of the rolled fin material, toward the curved center portion. A serrate processing step of inclining each tip portion, and a straightening process of rolling the root portion, which is the other side portion of the band-shaped fin material, to correct the curved shape of the fin material so that adjacent tip portions overlap each other. In the process, the overlapping tip portion is rolled, and the extension of the tip portion in the longitudinal direction of the fin material is regulated so that the length of the tip portion in the longitudinal direction is extended without changing the length of the tip portion. A fin material for a heat transfer tube. 9. The band-shaped fin material according to claim 6, wound on a fin take-up reel, and the band-shaped fin material is sent out from the take-up reel to the surface of the heat transfer tube, and a side edge of a root portion of the band-shaped fin material is provided. A method for manufacturing a finned heat transfer tube, comprising continuously welding a portion to the surface of the heat transfer tube to fix a band-shaped fin material spirally to the surface of the heat transfer tube. 10. A waste heat recovery boiler provided with the finned heat transfer tube according to any one of claims 1 to 5.