JP2001091184A - Internally grooved heating tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internally grooved heating tube produced by electric stitching system in which the ridge part of a roll in a grooving mill is protected from chipping. SOLUTION: Under developed state, inner surface of a heating tube 1 is sectioned into a plurality of regions R1, R2,..., Rn of specified width continuous in the length direction. A large number of fins 10 having a specified torsional angle θ with respect to the tube axis are formed in the odd regions R1 when viewed from one side and a large number of fins 11 having a specified torsional angle -q with respect to the tube axis are formed in the even regions R2. The height h or the base part width w of the fins 10, 11 increases gradually toward the boundary part 12 of odd and even regions R1, R2 and the maximum value of the height h or the base part width w is in the range of 1.04-1.3 of the minimum value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner grooved heat transfer tube used for a heat exchanger for an air conditioner or the like.

[0002]

2. Description of the Related Art As a heat transfer tube with an inner surface groove which is used as an evaporator tube or a condenser tube in a heat exchanger or the like and which can obtain high heat exchange performance, for example, as described in JP-A-9-42880, A heat transfer tube has been proposed in which a large number of fins are formed on the inner surface of the tube in a zigzag manner along the circumferential direction. As shown in FIG. 9, the heat transfer tube with an inner surface groove described in the above publication has an inner peripheral surface of the heat transfer tube 6 in a developed state divided into a plurality of regions R1 to R4 along a circumferential direction. In the state where the inner surface of the pipe is expanded, the torsion angle θ1 = 10 to the pipe axis is in the odd-numbered region R1.
While many fins 60 of 25 ° are formed in parallel,
The even-numbered regions R2.
A large number of fins 61 having θ1 = −10 to −25 ° are formed in parallel. The both sides in the width direction in the unfolded state are welded portions, and the vicinity of the welded portion is formed on a smooth surface 63. The fins 60 and 61 are formed such that the fin height and the fin base width are substantially uniform.

In order to manufacture a heat transfer tube as shown in FIG. 9, for example, as shown in FIG. 7, a metal strip 6a such as a copper alloy or an aluminum alloy wound on a reel 4 is drawn out while the metal strip 6a is grooved. The fins 60, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6.
Process 1 Thereafter, the metal strip 6a is formed into a tubular shape by a forming device having a group of forming rolls such that the fins are on the inside, and then the butted portions of the metal strip 6a are welded, and the metal strip 6a is vacuumed with a finishing die to manufacture the metal strip 6a. You.

[0004] As shown in FIG. 6, the grooved roll 5 in the grooving mill 50 shown in FIG.
1 ... The disks 51 to 54 made of cemented carbide having the same number and the same thickness as the number of Rn are fixed coaxially in a stacked state. Odd-numbered disks 51 and 53 of grooved roll 5
A number of parallel grooves 5a corresponding to the fins 60 in the odd-numbered regions R1 and R3 of the heat transfer tube 6 are formed on the outer peripheral surface of the heat transfer tube 6.
Heat transfer tubes 6 are provided on the outer peripheral surfaces of the even-numbered disks 52 and 54.
A large number of parallel grooves 5b corresponding to the fins 61 in the even-numbered regions R2 and R4 are formed. Each groove 5a has a torsion angle β1 corresponding to a torsion angle θ1 with respect to a cross section orthogonal to the axis of the roll 5, and each groove 5b has a torsion angle with respect to a cross section orthogonal to the axis of the roll 5. It has a twist angle -β1 corresponding to -θ1.

[0005]

A conventional heat transfer tube 6 with an inner groove is provided with fins 60, 6 by a groove processing and rolling mill 50 as shown in FIG.
In the case where the roll 1 is formed, assuming that the sheet passes in the direction of arrow A in FIG.
The fins 60, 61 shown in FIG. 9 are formed by moving along the grooves 5a, 5b of 1, 53, 52, 54 in a direction opposite to the feeding direction (a metal flow is generated). The movement of the material of the metal strip will be described in an enlarged manner with reference to FIG. 8. When the fins 60 and 61 are formed, the metal material moves in the direction of arrow B, and the metal material moves to the boundary 62 between the regions R1 and R2. The pressure of the flow is concentrated, and the grooves 60a between the adjacent fins 60, and the grooves 61a between the adjacent fins 61, 61 merge into the portion 62a of the disk. Part of the mountain is missing. Such chipping of the ridges of the disks 51 to 54 may be caused by, for example, a fin height of 0.1
0-0.30mm, fin base width 0.10-0.25m
It occurs more frequently when forming sharp fins 60 and 61 such as m. If the ridges between the grooves 5a and 5b of the disk are chipped, the fins 60 and 61 cannot be processed as designed, so that the heat transfer performance of the heat transfer tube is reduced. In addition, when the chip of the disk peak becomes large, the roll must be replaced, which lowers the production efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inner grooved heat transfer tube in an inner grooved tube manufactured by an electric resistance welding method, in which a ridge of a roll of a grooving mill is less likely to be chipped.

[0007]

Means for Solving the Problems A heat transfer tube with an inner groove according to the present invention is configured as follows to solve the above-mentioned problems. That is, in the heat transfer tube with the inner surface groove according to the first aspect, in the unfolded state, the inner surface of the heat transfer tube 1 is divided into a plurality of regions R1, R2,. A large number of fins 10 having a predetermined (preferably 5 to 30 °) torsion angle θ with respect to the tube axis are formed in the odd-numbered region R1 as viewed from the part, and the even-numbered region R2 is formed with a tube axis. For a predetermined (preferably -5 to-
30)), and each of the fins 10, 11 has a fin height h toward a boundary 12 between the odd-numbered region R1 and the even-numbered region R2. Alternatively, the fin base width w is gradually increased, and the maximum value of the fin height h or the fin base width w is 1.04 to 1.3 times the minimum value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a heat transfer tube with an inner groove according to the present invention will be described with reference to FIGS. FIG. 1 is a partially developed view showing a state where an inner surface of an inner grooved heat transfer tube according to an embodiment of the present invention is developed by cutting a welded portion.

The inner surface of the metal (in this embodiment, copper) grooved heat transfer tube 1 is divided into a plurality of regions R1, R2, R3, and R4 having a predetermined width that are continuous in the length direction in a developed state. . The number of the regions is appropriately selected depending on the dimensions of the heat transfer tube to be manufactured and other conditions, and the number of the regions may be not limited to an even number. In the heat transfer tube 1 in the unfolded state, the odd-numbered region R when viewed from one side.
1 and R2, a large number of fins 10 having a twist angle θ of 5 to 30 ° with respect to the tube axis are formed, and even-numbered regions R
2, R4 has a twist angle of -5 to -30 degrees with respect to the pipe axis.
Many fins 11 having θ are formed. The lines passing through the centers of the adjacent fins 10 and fins 11 are parallel. On the inner surface of the heat transfer tube 1,
A smooth portion 13 having no fins 10 or 11 is formed near the weld portion 14.

The fins 10 and 11 have a fin base width w toward a boundary 12 between the odd-numbered region R1 and the even-numbered region R2 except for the vicinity of the welded portion 14 including the smooth portion 13. Gradually increases, and the fin base maximum width w2 is 1.04 to 1..
The range is three times. In each of the fins 10 and 11 except for the vicinity of the welded portion 14 including the smooth portion 13, the fin height h gradually increases toward the boundary portion 12 between the odd-numbered region R1 and the even-numbered region R2. The maximum fin height h2 is in the range of 1.04 to 1.3 times the minimum fin height h1. Since the fin base width w of each of the fins 10 and 11 gradually increases toward the boundary portion 12 as described above, the width of each groove 10a between the fins 10 and each groove 11a between the fins 11 is , Gradually narrowing toward the boundary 12.

The reason why the fin base width w or the fin height h of the fins 10 and 11 is gradually increased toward the boundary portion 12 is that the fins 10 and 11 become closer to the boundary portion 12.
This is to increase the cross-sectional area of. Therefore, the fin base width w or the fin height h may be configured to gradually increase toward the boundary portion 12, or both may be configured to gradually increase.

In order to manufacture the heat transfer tube 1 with an inner surface having the above structure, a grooved roll 2 as shown in FIGS. 3 to 5 is used. The grooved roll 2 is provided in the regions R1 to R on the inner surface of the heat transfer tube.
Discs 21 to 24 made of cemented carbide or the like to correspond to No. 4
Are fixed coaxially, and fins 10 on the inner surface of the heat transfer tube are provided on the surfaces of the odd-numbered disks 21 and 23 from one end.
Grooves 2a corresponding to the even-numbered disks 2
Grooves 2b corresponding to the fins 11 on the inner surface of the heat transfer tube are formed on the surfaces of the heat transfer tubes 2, 24. Accordingly, the grooves 2a of the odd-numbered disks 21 and 23 have a twist angle β of 5 to 30 ° with respect to a cross section orthogonal to the axis of the roll 2, and the grooves 2b of the even-numbered disks 22 and 24 It has a twist angle-[beta] of -5 to -30 with respect to a cross section orthogonal to the second axis.

Each of the grooves 2a and 2b is provided with an odd-numbered disk 2.
1, 23 and the even-numbered disks 22 adjacent to them,
The groove depth d gradually increases toward the contact portion 25 with the groove 24, and the groove width w ′ gradually increases toward the contact portion 25. The maximum groove depth d2 is the minimum groove depth d2
And the maximum groove width w′2 is 1.04 to 1.3 times the minimum groove width w′1.

The grooving roll 5 of the grooving mill 50 shown in FIG. 7 is replaced with the grooving roll 2 shown in FIG. 3, and the metal strip is rolled by this rolling mill.
11 is processed, the metal strip is rounded into a tube so that the surface on which the fins 10 and 11 are formed is inward, the butt portion is welded, and this is emptied with a finishing die, thereby obtaining the inner surface of the above embodiment. The grooved heat transfer tube 1 is manufactured.

According to the inner grooved heat transfer tube 1 of the embodiment, each of the fins 10 and 11 has a fin height h and a fin height toward the boundary 12 between the odd-numbered region R1 and the even-numbered region R2. Since the base width w is gradually increased, when the fins 10 and 11 are formed by rolling, even if the material of the metal strip moves in the direction of arrow B in FIG. The cross-sectional area of 10, 11 gradually increases as approaching the boundary portion 12, and the pressure of the metal flow is absorbed by the expansion of the cross-sectional area.
Therefore, chipping of the crests of the grooved roll is prevented, and high-density and sharper fins are formed smoothly, so that a heat transfer tube having high heat transfer performance can be obtained.

EXAMPLE A fin was formed on one surface of a metal strip made of phosphor deoxidized copper having a width of 25 mm and a thickness of 0.5 mm using a grooved roll having a basic structure as shown in FIG. As shown in FIG. 1, the metal strip has four strip-shaped portions equally in the width direction except for the smooth portions 13 and 13 on both sides of the strip (the width of each of the smooth portions 13 is about 1.5 mm and a total of 3 mm). In the odd-numbered area from one side, fins having a twist angle θ of 15 ° with respect to the length direction are formed at a pitch of 0.5 mm (center spacing between adjacent fins). Fins having a twist angle -θ of -15 ° with respect to the length direction were formed in the region at a similar pitch. As shown in Table 1, the minimum fin height h of the fins
1 and the maximum fin height w2, and the difference between the minimum fin base width w1 and the maximum fin base width w2 are variously processed. Certain comparative metal strips were processed. Table 1 shows a comparison of the life of the grooved roll (gross tonnage of the fin-finished metal strip before the surface of the grooved roll was chipped) in each of the grooved rolling mills.

Table 1 (h1) (h2) (h2 / h1) (w1) (w2) (w2 / w1) Roll with groove mm mm mm mm Life ton Example 1 0.20 0.24 1.2 0.15 0.18 1.2 230 Example 2 0.20 0.20 1.0 0.15 0.18 1.2 180 Example 3 0.20 0.24 1.2 0.15 0.15 1.0 170 Example 4 0.20 0.26 1.3 0.15 0.15 1.0 140 Example 5 0.20 0.20 1.0 0.15 0.195 1.3 150 Example 6 0.20 0.208 1.04 0.15 0.15 1.0 140 Example 7 0.20 0.20 1.0 0.15 0.156 1.04 140 Comparative Example 1 0.20 0.28 1.4 0.15 0.21 1.4 90 Comparative Example 2 0.20 0.28 1.4 0.15 0.15 1.0 80 Comparative Example 3 0.20 0.20 1.0 0.15 0.21 1.4 80 Comparative Example 4 0.20 0.206 1.03 0.15 0.15 1.0 70 Comparative Example 5 0.20 0.20 1.0 0.15 0.155 1.03 60 Comparative Example 6 0.20 0.20 1.0 0.15 0.15 1.0 30

As shown in Table 1, according to the embodiment of the present invention, the life of the grooved roll is at least 140 tons and the maximum is 230 tons, whereas the comparative examples have 90 tons.
on. From these results, the fin height h
Alternatively, if the maximum value of the fin base width w is not more than 1.03 times the minimum value, the effect is not sufficient, and if the maximum value is not less than 1.4 times the minimum value, the adjacent grooves in the grooved roll will be insufficient. It has been found that the width of the mountain between them is so narrow that the roll is easily chipped.

[0019]

According to the heat transfer tube with an inner groove according to the present invention,
Each of the fins 10 and 11 has a fin height h or a fin base width w gradually increasing toward a boundary portion 12 between the odd-numbered region R1 and the even-numbered region R2, and the cross-sectional area is gradually increased. When the fins 10 and 11 are formed by rolling, the pressure due to the metal flow in the direction of the boundary 12 is absorbed by the enlargement of the cross-sectional area. Therefore, chipping of the crests of the grooved roll is prevented, the life thereof is extended, and high-density and sharper fins are smoothly formed, so that a heat transfer tube having higher heat transfer performance is manufactured.

[Brief description of the drawings]

FIG. 1 is a partially developed view showing an inner surface of an internally grooved heat transfer tube according to an embodiment of the present invention, which is developed from a welded portion.

FIG. 2 (a) is a right side view of the developed view of FIG. 1,
FIG. 2B is a partially enlarged cross-sectional view along the arrow AA in FIG.

FIG. 3 is a front view of a grooved roll for producing the heat transfer tube with an inner surface groove of FIG. 1;

FIG. 4 is an enlarged sectional view taken along arrow BB in FIG. 3;

FIG. 5 is a partially enlarged front view of the grooved roll of FIG. 3;

FIG. 6 is a front view of a grooved roll for manufacturing the conventional heat transfer tube with internal grooves of FIG. 9;

FIG. 7 is a schematic front view of a grooving rolling mill in a manufacturing process of the heat transfer tube with an inner groove.

FIG. 8 is a partially enlarged development plan view in which a part of the conventional heat transfer tube with an inner surface groove of FIG. 9 is enlarged.

FIG. 9 is a partially developed plan view showing the inside of a conventional heat transfer tube with an inner groove developed from a welded portion.

[Explanation of symbols]

R1-Rn region θ, -θ, θ1, -θ1, β, -β, β1, -β1 Helix angle h Fin height w Fin base width h1 Minimum fin height h2 Maximum fin height w1 Minimum fin base width w2 Maximum Fin base width d Groove depth w 'Groove width d1 Minimum groove depth d2 Maximum groove depth w'1 Minimum groove width w'2 Maximum groove width 1,6 Heat transfer tubes with internal grooves 10, 11, 60, 61 Fins 12 , 62 Boundary part 10a, 11a, 60a, 61a Groove 13, 63 Smooth part 14 Welded part 2, 5 Grooved roll 50 Grooving mill 21, 22, 23, 24, 51, 52, 53, 54 Disc 2a, 1b , 5a, 5b Groove 25 Disc contact part 3 Work roll 30 Backup roll 4 Reel

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasutoshi Mori 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Toshiaki Hashizume 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (1)

[Claims] In an unfolded state, the inner surface of the heat transfer tube 1 has a plurality of regions R1, R2,...
··· Rn, a large number of fins 10 having a predetermined twist angle θ with respect to the tube axis are formed in the odd-numbered region R1 when viewed from one side, and the tube shaft is formed in the even-numbered region R2. Given twist angle-
are formed, and each of the fins 10 and 11 gradually increases in fin height h or fin base width w toward the boundary 12 between the odd-numbered region R1 and the even-numbered region R2. Wherein the maximum value of the fin height h or the fin base width w is 1.04 to 1.3 times the minimum value.