JPH10323730A - Manufacture of heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase productivity and decrease a price of a product by stably forming a tall inner fin. SOLUTION: A process for the manufacturing a heat exchanger comprises arranging many radiation fins 2 at the outside of a heat exchanger pipe 1, inserting a plug 3, through circulating, in the heat exchanger pipe 1, integrating the radiation fins 2 with the heat exchanger pipe 1 and simultaneously revolving a convey type tools 4 to cut and raise a spiral inner fin parts 6, wherein the heat exchanger pipe 1 is expanded by pushing a plurality of protrusions (ball 5), which are formed on the outside of the plug 3, to the inside wall of the pipe 1 along the circular direction of the outside of the plug 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat exchanger in which a large number of radiating fins are mounted on the outer surface of a heat transfer tube and the inner fins are formed on the inner surface of the heat transfer tube.

[0002]

2. Description of the Related Art As such a heat exchanger, there is an absorber provided in an absorption refrigerator or an absorption heat pump. This absorber absorbs water vapor generated in the evaporator into an absorbent such as lithium bromide having a high concentration, and removes the generated heat of absorption through a heat transfer tube.

[0003] As this absorber, a large number of heat transfer tubes are horizontally arranged in a closed vessel, and the absorbing liquid is dropped or sprayed on the outside of the heat transfer tubes, and cooling water is flown inside the heat transfer tubes.
Generally, the absorption liquid is cooled, but the absorption liquid flows down inside the vertically arranged heat transfer tube, comes into contact with the water vapor passing inside, and the generated absorption heat is air-cooled from the outside of the heat transfer tube. Recently, it is being put to practical use.

As the heat transfer tube used in the latter type of absorber, an inner grooved tube having an inner fin formed on the inner surface thereof is used, and a number of radiating fins made of aluminum or the like are fixed to the outer surface of the heat transfer tube. Thus, the heat transfer efficiency is increased by these.

[0005] As a manufacturing method for fixing the radiation fins in such an absorber, a method is generally used in which the diameter of the heat transfer tube is expanded, and the heat transfer tube and the radiation fin are integrated into each other.

[0006] To expand the diameter of the heat transfer tube, first, a diameter expansion plug is pressed into a hollow portion of the heat transfer tube to expand the diameter, and second, a liquid pressure such as water or oil is introduced into the heat transfer tube. There is a method of enlarging the diameter by acting. In the former case, a grooved tool with a threaded groove formed on the enlarged diameter plug is connected in series, and while the diameter of the heat transfer tube is expanded, the grooved tool is cut into the inner surface to form a spiral groove. (See Japanese Patent Publication No. 52-34436).

[0007]

However, among the conventional methods of manufacturing an absorber, the method of press-fitting an enlarged diameter plug has the advantage that it can be easily industrialized without requiring any special technique. When press fitting a diameter plug,
Even if the internal fins are formed in advance on the inner surface of the heat transfer tube, the internal fins are crushed when the diameter-expanding plug is pressed in, and the expected heat transfer efficiency cannot be achieved. I can't let it.

[0008] In the conventional method for manufacturing an absorber,
In the case of expanding the diameter of the heat transfer tube by liquid pressure, it is possible to expand the diameter without crushing the internal fins, but the manufacturing equipment has a liquid-tight structure, and complicated setup must be performed every time the hydraulic pressure is applied to each heat transfer tube However, it is not suitable for mass production at all, and there is a problem that if it is adopted, the price of the product will increase.

[0009] Further, the heat transfer tube manufactured in Japanese Patent Publication No. 52-34436 is not so large because the grooved effect of the grooved tool is not so large, and a large internal fin cannot be formed. Did not contribute much to the improvement of the heat transfer efficiency.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to stably form a large internal fin, thereby increasing heat transfer efficiency. It is an object of the present invention to provide a method for manufacturing a heat exchanger.

[0011]

According to a method of manufacturing a heat exchanger of the present invention, a large number of radiating fins are arranged on the outer surface of a heat transfer tube, and a plug is rotated and inserted into the heat transfer tube to expand the heat transfer tube. A method for manufacturing a heat exchanger that integrates the heat radiating fins and the heat transfer tube, and cuts and raises a helical internal fin portion by rotating a convex tool into the inner wall of the expanded heat transfer tube while rotating the convex tool. Then, a plurality of protrusions formed along the circumferential direction on the outer peripheral surface of the plug are pressed against the inner wall of the heat transfer tube to expand the diameter of the heat transfer tube.

It is preferable that the projection is an external spherical body. Further, it is preferable that the convex portion is constituted by a ball rotatably mounted on the outer peripheral surface of the plug.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a heat exchanger according to an embodiment of the present invention will be described below.

According to the present manufacturing method, the heat transfer tube 1 is inserted into a hole formed in the heat radiation fin 2 and having a diameter slightly larger than the outer diameter of the heat transfer tube 1, and the plug 3 is rotated inside the heat transfer tube 1 as shown in FIG. The plurality of balls 5 (corresponding to the projections of the present invention) which are inserted in the direction of arrow a in the middle and formed on the outer peripheral surface of the plug 3 are pressed against the inner wall of the heat transfer tube 1 while rotating, thereby expanding the diameter of the heat transfer tube 1. As shown in FIG. 3, a plurality of convex tools 4 rotating integrally with the plug 3 are cut into the inner wall of the heat transfer tube 1 while integrating the radiation fins 2 and the heat transfer tube 1 to form a helical interior. The fin 6 and the groove 7 are cut and raised.

In a conventional method for manufacturing a heat exchanger in which a diameter-expanding plug is press-fitted into the heat transfer tube 1 and the diameter of the heat-exchanger tube is expanded on the peripheral surface of the diameter-expanding plug, the inner surface of the heat transfer tube 1 is cut simultaneously with press-fitting by a convex tool 4. If this occurs, the friction between the enlarged diameter plug and the inner surface of the heat transfer tube 1 is large, so that the rotation and insertion of the enlarged diameter plug are not performed smoothly, and the cutting and raising of the internal fin portion 6 by the convex tool 4 becomes unstable.

However, according to the manufacturing method of the present embodiment, the diameter of the heat transfer tube 1 is increased by pressing a plurality of balls 5 rotatably attached to the plug 3 against the inner surface. Then, the ball 5 rolls while making point contact with the inner surface. Therefore, a large load such as a frictional force does not act on the plug 3, and the plug 3 can be smoothly rotated and inserted. Thus, the internal fins 6 can be stably cut and raised by the convex tool 4.

Further, since the convex tool 4 is made to bite into the inner wall of the heat transfer tube 1 so that the inner fin portion 6 is greatly cut and raised, the inner fin portion 6 which is higher than the conventional one is formed.
Can be formed.

Further, the inner fin portion 6 can be formed almost simultaneously with the diameter expansion by the ball 5, and the same productivity as the manufacturing method using the diameter expansion plug is secured. In addition, since the internal fins 6 are cut and raised on the inner surface of the heat transfer tube 1 after the diameter expansion, the formation of the internal fins 6 is not affected by the diameter expansion at all, and the internal fins 6 are surely high. The part 6 can be formed. Therefore, the heat exchanger manufactured by this manufacturing method has high heat transfer efficiency.

In this manufacturing method, since the plug 3 is rotated, the internal fin portion 6 is cut and raised by the convex tool 4 which rotates integrally with the plug 3.
A spiral internal fin portion 6 can be formed, and the internal fin portion 6 is opposed to the flow of the fluid flowing inside the heat transfer tube, which induces turbulence in the fluid and improves heat transfer efficiency. Can be done.

The plurality of convex tools 4 are arranged and the plug 3 is rotated so that the other convex tool 4 enters the groove 7 formed by one of the convex tools 4. Preferably, the amount and the insertion amount are synchronized. In this case, since the other convex tool 4 enters and is guided by the groove 7 formed by one convex tool 4, the other convex tool 4 follows the spiral groove 7 by rotation of the plug 3. Then, a propulsive force for propelling the plug 3 in the insertion direction acts. Therefore, the insertion force of the plug 3 can be reduced.

Although the plug 3 is inserted into the heat transfer tube 1 in the above-described manufacturing method, the plug 3 is rotatably fixed, and the heat transfer tube 1 is moved together with the radiating fins 2 in the axial direction of the heat transfer tube 1. The heat transfer tube 2 while rotating the plug 3.
The same effect can be obtained by inserting it in the inside.

Further, a tube in which a groove is formed in advance inside the heat transfer tube 1 may be used.

It should be noted that various structures can be used as an apparatus for carrying out the method for manufacturing the inner grooved pipe. However, in order to facilitate understanding of the manufacturing method, one of them will be described below. A device as a specific example will be described.

As shown in FIG. 2, the present apparatus comprises a holder 10 for holding a plate-shaped heat radiation fin 2,
, A plurality of rods 12 protruding from the frame 11, a moving table 13 connected to the other end of the rod 12, a rotation driving device 14 provided on the moving table 13, It comprises a mandrel 8 connected to a rotating shaft (not shown) of a rotary drive device 14 and a plug 3 attached to the tip of the mandrel 8 so as to rotate integrally with the mandrel 8.

The movable table 13 is provided with a drive mechanism (not shown), and the movable table 13 can be moved along the rod 12 by driving the drive mechanism.

As shown in FIG. 1, the plug 3 has a cylindrical shape having an outer diameter smaller than the inner diameter of the heat transfer tube 1, and a plurality of balls 5 are arranged on the outer peripheral surface at predetermined intervals in the circumferential direction. Have been. Almost half of these balls 5 are arranged in a state of being housed in a hemispherical recess formed in the plug 3, and each ball 5 can rotate in the recess.

Two convex tools (bites) 4 are detachably fixed to the base end of the plug 3. These convex tools 4 are arranged radially from each other, and are arranged such that the cutting edges are shifted from each other in the axial direction of the plug 3 (the insertion direction of the plug 3).

In a device in which the diameter-expanding plug is pressed into the heat transfer tube 1 and the diameter is expanded on the peripheral surface of the diameter-expanding plug, when the inner surface of the heat transfer tube 1 is cut and raised simultaneously with the press-fitting by the convex tool 4, the expansion is performed. The outer peripheral surface of the diameter plug and the inner surface of the heat transfer tube 1 come into surface contact with each other, and a large frictional force acts, so that the rotation and insertion of the enlarged diameter plug cannot be performed smoothly. For this reason, cutting and raising of the internal fin by the convex tool 4 becomes unstable.

However, in the present embodiment, the diameter of the heat transfer tube 1 is increased by pressing against the inner surface of the plurality of balls 5 rotatably mounted on the plug 3, so that the balls 5 roll in point contact. I do. Therefore, when expanding the diameter, the plug 3
The plug 3 can be smoothly rotated and inserted without a large load such as a frictional force acting on the plug 3. As a result, the internal fin portion 6 can be stably cut and raised by the convex tool 4.

Since the plugs 3 are arranged radially, the center is automatically adjusted when the plug 3 is inserted into the heat transfer tube 1 and the internal fin portion 6 is cut and raised by each of the convex tools 4, so that misalignment can be prevented. .

The other convex tool 4 is guided and follows the groove 7 formed when cut and raised by the preceding convex tool 4, and a propulsive force is generated in the insertion direction of the plug 3.

Each of the convex tools 4 has a predetermined width in the rotation direction thereof, and is formed in a groove 7 formed by cutting and raising the front end of the convex tool 4 in the rotation direction. If the end portion and the middle portion are made to enter, a propulsive force can be generated in the insertion direction of the plug 3. In this case, it is not necessary to shift the cutting edges of the plurality of convex tools 4 in the axial direction of the plug 3.

Even when the convex tool 4 is twisted along the traveling direction of the convex tool 4, a propulsive force can be similarly generated in the plug insertion direction.

In the above-described embodiment, the diameter of the heat transfer tube 1 is increased by pressing the ball 5 provided on the plug 3 while rotating the ball 5. However, a convex portion (for example, a conical projection) provided integrally with the plug 3 is used. And outer hemispherical projections), the load such as frictional force acting on the plug 3 when the diameter is expanded can be reduced, and the inner fin portion 6 can be formed stably as in the above-described embodiment. it can.

[0035]

As described above, in the present invention, a plurality of projections formed on the outer peripheral surface of the plug along the circumferential direction are pressed against the inner wall of the heat transfer tube to expand the diameter of the heat transfer tube. The load acting on the plug can be reduced, and the plug can be smoothly rotated and inserted, so that a large internal fin can be formed stably and the heat transfer efficiency can be increased. Productivity is high and product prices can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of an apparatus used for a method for manufacturing a heat exchanger of the present invention.

FIG. 2 is a diagram showing an entire configuration of an apparatus used for a method of manufacturing a heat exchanger according to the present invention.

FIG. 3 shows the operation of the device of FIGS. 1 and 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat transfer tube 2 Radiation fin 3 Plug 4 Convex tool 5 Ball (convex part) 6 Internal fin part 7 Groove part

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F28F 1/42 F28F 1/42 C

Claims (3)

[Claims] A plurality of heat dissipating fins arranged on an outer surface of the heat transfer tube, a plug inserted into the heat transfer tube while rotating, the diameter of the heat transfer tube is increased, and the heat dissipating fin and the heat transfer tube are integrated; A method of manufacturing a heat exchanger for cutting a spiral internal fin portion by rotating and projecting a convex tool into an inner wall of a heat transfer tube whose diameter has been increased, wherein the heat exchanger is formed along a circumferential direction on an outer peripheral surface of the plug. A method for manufacturing a heat exchanger, wherein the plurality of projected portions are pressed against the inner wall of the heat transfer tube to expand the diameter of the heat transfer tube. 2. The method according to claim 1, wherein the convex portion is an external spherical body. 3. The method for manufacturing a heat exchanger according to claim 1, wherein the projection is formed of a ball rotatably mounted on an outer peripheral surface of the plug.