JP3353635B2 - Method for manufacturing inner spiral finned tube and apparatus for manufacturing the same - Google Patents

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 an inner spiral finned tube and an apparatus for manufacturing the same, and more particularly to a method for manufacturing an inner spiral finned tube used for an air conditioning heat exchanger and an apparatus for manufacturing the same. It is.

[0002]

2. Description of the Related Art As a heat transfer tube used in a heat exchanger for air conditioning, as shown in FIGS. 3 (a) and 3 (b), a tube 1 having an internal spiral fin 2 having a fine spiral fin 2 formed on the inner surface of the tube is used. Used.

[0003] As one of the methods for producing the inner spiral finned tube, there is a method of extruding with a rotary wheel type extruder.

As shown in FIG. 4, an apparatus for manufacturing a tube with internally spiral fins using a rotating wheel type extruder is firstly operated by frictional force with a rotating wheel 3 which is a metal material supply means having a groove 4 therein. The extruded metal material 11 is supplied to a collecting chamber 6 formed in a shoe block 5 provided in contact with the outer periphery of the rotating wheel 3. The deformation resistance of the metal material 11 in the collecting chamber 6 is reduced due to frictional heat and deformation heat.

[0005] Here, an extruding die 7 is fitted and provided at one end in the collecting chamber 6, and a mandrel 19 rotatable to face the collecting chamber 6 is provided at the other end in the collecting chamber 6. It is provided through the block 5. Further, the grooved portion 20 at the tip of the mandrel 19 is disposed so as to be located at the extrusion portion 8 of the extrusion die 7.

The metal material 11 is extruded from the gap between the extruded portion 8 of the extrusion die 7 and the grooved portion 20 of the mandrel 19 due to the increase in the pressure in the collecting chamber 6, and the inner surface is spiraled by rotating the mandrel 19. The inner spiral finned tube 1 on which the fins 2 are formed is obtained.

[0007] In order to improve the heat exchange rate, a spiral fin with a thin fin thickness and a high fin height is desired for a tube with an internal spiral fin used in a heat exchanger for air conditioning.

[0008]

However, when extruding a metal having a large contact frictional resistance such as Al using the above-described rotary wheel type extruder, the frictional resistance between the grooved portion 20 of the mandrel 19 and the metal material 11 is reduced. Is larger than the frictional resistance between the extruded portion 8 of the extrusion die 7 and the metal material 11. Therefore, the flow of the metal material 11 is smaller on the grooved portion 20 side of the mandrel 19 than on the extrusion portion 8 side of the extrusion die 7.

This tendency is caused by the grooved portion 20 of the mandrel 19.
Becomes more noticeable as the groove width becomes narrower (fin thickness becomes thinner) and the groove depth becomes deeper (fin height becomes higher).
Eventually, the metal material 11 does not flow into the groove, and the fin height of the spiral fin 2 does not increase even if the groove is deepened.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method of manufacturing a tube with an internal spiral fin having a small fin thickness and a high fin height, and an apparatus for producing the same.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to supply a metal material into a collecting chamber, and to provide an extruding die provided in the collecting chamber and a grooved portion of a rotating mandrel. In the method for manufacturing a tube with an internal spiral fin by extruding from between the above, the length l in the longitudinal direction of the mandrel of the linear or spiral grooved portion formed at the tip of the mandrel is represented by l ≦ (0.6 / H) (where h is the depth of the groove of the grooved portion), and a spiral fin is formed by reducing the frictional resistance between the metal material and the grooved portion of the mandrel.

According to a second aspect of the present invention, a metal material collecting chamber is formed in a shoe block provided in contact with the outer periphery of a rotating wheel serving as a metal material supplying means, and an extrusion die is fitted to one end of the collecting chamber. The mandrel is rotatably provided so as to penetrate the shoe block and face the other end in the collecting chamber, and the linear or spiral grooved portion formed at the tip of the mandrel is formed by the extrusion die. In the apparatus for manufacturing a tube with internal helical fins using a rotary wheel type extruder arranged in the extruding section, the length l in the longitudinal direction of the mandrel of the grooved section for forming spiral fins on the internal surface of the pipe
Where l ≦ (0.6 / h) (where h is the depth of the groove in the grooved portion).

According to the above construction, the metal material is supplied into the collecting chamber, and the metal material is extruded from between the extrusion die provided in the collecting chamber and the grooved portion of the rotating mandrel to manufacture the tube with the internal spiral fins. In the method, the length l in the longitudinal direction of the mandrel of the linear or spiral grooved portion formed at the tip of the mandrel is expressed as: l ≦ (0.6 / h) (where h: groove of the grooved portion) In order to form the spiral fin by reducing the frictional resistance between the metal material and the grooved portion of the mandrel, the inner spiral fin has a thinner fin thickness and a higher fin height. You can get a tube.

[0014]

Embodiments of the present invention will be described below.

[0015] In order to obtain a tube with an inner spiral fin having a small fin thickness and a high fin height, it is necessary to reduce the frictional resistance between the grooved portion of the mandrel and the metal material so that the metal material can easily flow into the groove. There is. Since the frictional resistance between the grooved portion of the mandrel and the metal material increases in proportion to the depth of the groove and the length of the grooved portion, when the depth of the groove is deep, the length of the grooved portion in the longitudinal direction of the mandrel is increased. By reducing the length, it is possible to prevent an increase in frictional resistance between the grooved portion of the mandrel and the metal material.

As a result of intensive studies conducted by the present inventors, when the depth of the groove of the grooved portion is h, by setting the length 1 of the grooved portion in the longitudinal direction of the mandrel to 0.6 / h or less, It has been found that the frictional resistance between the grooved portion and the metal material can be suppressed to a degree sufficient for the metal material to flow into the groove.

FIG. 1 is a structural view of a mandrel used for manufacturing the tube with an internal spiral fin according to the present invention. 1A shows a side view of the mandrel, FIG. 1B shows a cross-sectional view of the grooved portion, and FIG. 1C shows an enlarged view of a main part of FIG. 1B.

The basic configuration of the manufacturing apparatus for the tube with internal fins using the rotating wheel type extruder of the present invention is basically the same as the manufacturing apparatus shown in FIG. 4, but FIGS.
As shown in (c), the grooved portion 10 in the mandrel 9
When the length of the mandrel in the longitudinal direction is 1 and the depth of the groove is h, the length 1 of the grooved portion is 0.6 / h or less. At this time, the outer diameter of the grooved portion 10 is D, and the vertical angle of the groove is θ.
And

The material of the grooved portion 10 of the mandrel 9 is not particularly limited, and is appropriately selected according to the metal material used.

The outer diameter D of the grooved portion is not particularly limited, and is appropriately selected according to the outer diameter and the wall thickness of the inner spiral finned tube.

The groove apex angle θ is not particularly limited, and is appropriately selected according to the fin thickness of the spiral fin in the inner spiral fin tube.

Next, the manufacturing method of the present invention will be described.

First, a metal material extruded by a frictional force with a rotating wheel, which is a metal material supply means having a groove therein, is supplied to a collecting chamber formed in a shoe block provided in contact with the outer periphery of the rotating wheel. To supply. The deformation resistance of the metal material in the collecting chamber is reduced due to frictional heat and deformation heat.

Here, an extrusion die is provided at one end of the collecting chamber so as to be fitted thereto, and a mandrel rotatable to face the collecting chamber is provided at the other end of the collecting chamber through the shoe block. ing. Further, the grooved portion at the tip of the mandrel is arranged so as to be located at the extrusion portion of the extrusion die. Further, the length 1 of the grooved portion in the mandrel in the longitudinal direction of the mandrel and the depth h of the groove are 1 ≦ 0.6 /
h.

By supplying the metal material into the collecting chamber, the pressure in the collecting chamber is increased, and the metal material is extruded from the gap between the extruded portion of the extrusion die and the grooved portion of the mandrel.
At this time, by rotating the mandrel, an inner spiral fin tube having spiral fins formed on the inner surface is obtained.

That is, in the method for manufacturing a tube with an inner spiral fin according to the present invention, since the length l of the grooved portion of the mandrel in the longitudinal direction of the mandrel and the depth h of the groove are controlled, the grooved portion and the metal The frictional resistance with the material can be suppressed to a level sufficient for the metal material to flow into the groove, and a tube with an inner spiral fin having a small fin thickness and a high fin height can be obtained.

Further, since the fin thickness of the spiral fin in the inner spiral fin tube and the fin height are increased, the heat transfer performance of the heat exchanger is improved, and the heat exchanger is further reduced in size. The weight can be reduced.

[0028]

【Example】

(Example 1) In an apparatus for manufacturing a tube with internal spiral fins using a rotary wheel type extruder, an outer diameter of a grooved portion was 6.2 m.
m, groove depth h is 0.3 mm, groove vertex angle θ is 20 °, grooved portion length 1 is 1 (l ≦ 0.6 / h = 0.6 / 0.3 = 2)
A tube with internal spiral fins is made using a mm mandrel.

(Comparative Example 1) In an apparatus for manufacturing a tube with internal spiral fins using a rotating wheel type extruder, the outer diameter of the grooved portion is 6.2 mm, the depth h of the groove is 0.3 mm, and the groove apex angle. An inner spiral finned tube is manufactured using a mandrel having θ of 20 ° and a grooved portion length 1 of 3 mm.

FIG. 2 shows the ratio of the fin height to the groove depth in the mandrels of Example 1 and Comparative Example 1.

As shown in FIG. 2, the ratio of the fin height to the groove depth in the mandrel of Example 1 (about 96%)
Is about 1.5 times the ratio of the fin height to the groove depth (about 64%) in the mandrel of Comparative Example 1 (mandrel with l = 3), and the grooved portion of the mandrel in the longitudinal direction of the mandrel. By controlling the length 1 and the depth h of the groove, the frictional resistance between the grooved portion and the metal material can be suppressed, and a tube with an inner spiral fin having a small fin thickness and a high fin height can be obtained. Obtainable.

[0032]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) By controlling the length l of the grooved portion of the mandrel in the longitudinal direction of the mandrel and the depth h of the groove, the frictional resistance between the grooved portion and the metal material can be reduced by the metal material flowing into the groove. In addition to this, it is possible to obtain an inner spiral fin tube with a thin fin and a high fin height.

(2) The heat transfer performance of the heat exchanger is improved by reducing the fin thickness of the spiral fins and increasing the fin height in the tube with the internal spiral fins. Weight and weight can be reduced.

[Brief description of the drawings]

FIG. 1 is a structural view of a mandrel used for manufacturing a tube with internal spiral fins of the present invention.

FIG. 2 is a diagram showing a ratio of a fin height to a groove depth in mandrels of an example and a comparative example.

FIG. 3 is a sectional view of an inner spiral finned tube.

FIG. 4 is a longitudinal sectional view of an apparatus for manufacturing a tube with internal spiral fins using a rotary wheel type extruder.

[Explanation of symbols]

 Reference Signs List 2 spiral fin 3 rotating wheel 5 shoe block 6 collecting chamber 7 extrusion die 8 extrusion section 9 mandrel 10 grooved section 11 metal material

Continuation of the front page (72) Inventor Hiroshi Furuto 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki Hitachi Systems, Ltd. System Materials Research Laboratories (56) References JP-A-10-166033 (JP, A) Sho Akai 56-95418 (JP, U) JP-A-4-22113 (JP, U) JP-B-44-5317 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21C 23/10 B21C 23/21 B21C 25/04 F28F 1/40

Claims (2)

(57) [Claims] 1. A method for supplying a metal material into a collection chamber,
In a method of manufacturing a tube with an internal spiral fin by extruding from between an extrusion die provided in the collecting chamber and a grooved portion of a rotating mandrel, the linear or spiral grooved groove formed at the tip of the mandrel is formed. The length l in the longitudinal direction of the mandrel is l ≦ (0.6 / h) (where h is the depth of the groove of the grooved portion), and the frictional resistance between the metal material and the grooved portion of the mandrel is Forming a spiral fin by reducing the number of spiral fins. 2. A collecting chamber for a metal material is formed in a shoe block provided in contact with the outer periphery of a rotating wheel as metal material supply means, and an extrusion die is fitted and provided at one end in the collecting chamber. Penetrating the block, and, provided a mandrel rotatably facing the other end in the above-mentioned collection chamber,
A straight or spiral grooved portion formed at the tip of the mandrel is arranged in the extrusion portion of the extrusion die. The length l of the grooved portion in the longitudinal direction of the mandrel for forming the fin is given by l ≦ (0.6 / h) (where h is the depth of the groove of the grooved portion). For manufacturing tubes with internal spiral fins.