KR20130043659A - Internally grooved aluminum alloy heat transfer pipe - Google Patents

Abstract

It is related with the heat exchanger tube which fin crushing is hard to generate | occur | produce, excellent in corrosion resistance, and thinning.
A plurality of protruding fins are formed on the inner surface and contain Mn: 0.8-1.8% by mass (hereinafter referred to as% by mass), Cu: 0.3-0.8%, Si: 0.3-1.0%, and the balance is Al and Provided is a heat transfer tube having an inner groove made of an aluminum alloy, which is made of inevitable impurities.

Description

Heat pipe with inner groove made of aluminum alloy {INTERNALLY GROOVED ALUMINUM ALLOY HEAT TRANSFER PIPE}

The present invention relates to a heat transfer tube having an inner groove made of aluminum, which is used as a heat transfer tube of a cross fin type heat exchanger that can be used in a domestic air conditioner, a commercial air conditioner, a heat pump type water heater, and the like.

A heat exchanger (FIG. 1) of a general cross fin (also called a fin and tube type) inserts a heat transfer tube into an insertion hole opened in an aluminum heat dissipation fin, and then expands a mandrel for expansion having an outer diameter larger than its inner diameter inside the heat transfer tube ( MANDREL) is pushed in to expand the diameter of the heat transfer pipe, and the outer circumferential surface of the heat transfer tube and the insertion hole of the aluminum heat dissipation fin are brought into close contact with each other (expansion processing. Fig. 2). Thereafter, the heat transfer tube integrated with the aluminum heat dissipation fin is bent into a hairpin shape, and the heat transfer tube (U-shaped tube), which is separately bent in a U-shape, is joined by torch soldering (non-patent document 1).

The heat transfer tube used in the cross fin type heat exchanger is a heat transfer tube made of copper having a projecting fin having a trapezoidal or triangular cross section on the inner surface of the heat exchanger by flowing HFC or the like as a refrigerant in the tube. The method of increasing the efficiency of the heat exchanger and saving energy is being promoted by using a pipe having a diameter of the heat exchanger, and the depth of the grooves between the protrusion fins, the bottom thickness (the thickness of the base of the protrusion fin), and the fin Various heat transfer tubes which define the shape (vertical angle etc.) or the lead angle (arrangement angle of the pin with respect to the pipe longitudinal direction) of the projection fin shown in FIG. 5 are proposed (for example, patent document 1). It is said that the heat transfer performance of a tube having an inner groove is excellent because the surface area inside the tube is increased compared to the smooth tube, and a uniform coolant liquid film is formed in the tube by the groove (non-patent). Document 2).

In the pipe | tube inner surface of the pipe | tube which has an inner surface groove | channel, generally, the processus | protrusion process of a smooth pipe | tube is carried out, and the projection fin continuously arranged in a spiral form is formed. As a roll processing method, a roll rolling method for inserting a plug having a freely rotating groove in a pipe and pulling the pipe while pressing and rotating a freely rotating roll outside the pipe (see FIG. 3) or a ball pressing mechanism instead of a roll One ball rolling method is known (nonpatent literature 1, patent document 2).

Although copper-based materials such as copper and copper alloys have been mainly used for pipes having inner grooves, aluminum-based materials such as aluminum and aluminum alloys (hereinafter referred to as aluminum alloys) in order to reduce the cost of materials and meet the demand of weight reduction. Is under consideration.

However, when aluminum alloy is compared with a copper type material, corrosion resistance is anticipated to fall. Therefore, for example, in Patent Document 3, the heat transfer tube is a two-layer structure, the inner layer of the tube is made of Al-Mn-based alloy, and the outer surface layer is clad with an Al-Zn-based alloy as a sacrificial anticorrosive layer. A tube having an inner groove has been proposed.

Or in patent document 4, Al-Mn type alloys, such as A3003, are used for the inner layer of a heat exchanger tube, and the outer surface layer has the inner surface groove which clad Al-Zn type alloys, such as A7072, as a sacrificial anticorrosive layer, and the said inner surface Heat exchangers using grooved tubes are proposed.

On the other hand, in addition to the problem of corrosion resistance, when pipes having inner grooves made of these aluminum are expanded, so-called "pin crushing" occurs in which the head part of the protruding pins on the inner surface of the pipe is broken. There is a problem that the expected heat transfer performance cannot be obtained due to insufficient fin shape collapse and insufficient adhesion to the aluminum heat dissipation fins. This is because the material strength of the tube having aluminum or aluminum alloy inner grooves is lower than that of copper.

In order to solve the pin dent at the time of expansion pipe processing, in patent document 5, forming the oxide film with a thickness of 5 micrometers or more in the inner surface of an aluminum tube is proposed.

In addition, in Patent Document 6, the inner layer in which the protruding fin is formed is made of an aluminum alloy layer having a high mechanical strength, and an inner groove made of aluminum in which an aluminum layer having a small mechanical strength is clad on the outer layer of the aluminum alloy layer. Branch tubes are proposed. As a specific alloy, the example which used A3003 aluminum alloy as an inner layer and A1050 (pure aluminum) as an outer layer is shown. In this document, the outer circumferential tube bottom thickness portion made of A1050 is first deformed to expand the outer diameter, and the inner circumferential tube bottom thickness portion made of A3003 is expanded because the deformation amount is small. Even if it processes, it is demonstrated that the amount of crushing of the protrusion pin in an inner surface can be suppressed to below an allowable range.

In addition, Patent Literature 7 uses a high-strength alloy obtained by adding Zn to an outer layer material Al-Mn alloy (A3000 alloy) of an aluminum tube as a tube having an inner groove excellent in expansion pipe workability. Three-layer cladding pipes using Al-Mg-Si alloys (A6000 alloys) or Al-Mg-based alloys (A5000 alloys), which have a high strength of -Mn-based alloys (A3000-based alloys) and inner inner layer materials, have also been proposed. .

[Document 1] Japanese Unexamined Patent Publication No. 2003-287383 [Document 2] Japanese Unexamined Patent Publication No. 4-262818 [Document 3] Japanese Unexamined Patent Publication No. 2000-121270 [Document 4] Japanese Unexamined Patent Publication No. 2009-250562 [Document 5] Japanese Unexamined Patent Publication No. 2000-205782 [Document 6] Japanese Unexamined Patent Publication No. 11-351791 [Document 7] Japanese Unexamined Patent Publication No. 2008-266738

[Reference 1] Masaaki Ito: Electric Heat, 42, 174 (2003), 3 [Reference 2] Akio Isozaki Others: R & D Kobe Steel Making Announcement 50, 3 (2000), 66

However, the prior art described in the above documents has room for improvement in the following points.

First, in Patent Literature 1, Patent Literature 2, Non-Patent Literature 1, and Non-Patent Literature 2, corrosion resistance and pin crushing problems when the aluminum alloy was used in the heat transfer tube were not improved.

Second, Patent Document 3 and Patent Document 4 describe a method for improving the corrosion resistance of the heat transfer tube, but the pin crushing problem has not been improved.

In Patent Documents 5 to 7, Patent Document 5 describes a method for improving fin crushing of the heat transfer tube, but has room for improvement in the following points. In other words, in Patent Document 5, in order to add anodizing treatment or the like as a step of forming an oxide film therein, a significant improvement in processing cost is invited, which is not practical. It is also very difficult to perform such a treatment on the inside of a generally long pipe.

In patent document 6, it is necessary to make thickness ratio of pure aluminum of an outer layer thicker than A3003 alloy of an inner layer. In the two examples disclosed in the embodiment of the document, the A3003 inner layer is 0.2 mm for the A1050 outer layer is 0.8 mm, or the A3003 inner layer is 0.3 mm for the A1050 outer layer 0.7 mm. It is A1050. However, since such structure is lowered in the strength of the tube itself, it is necessary to make the tube thicker in order to obtain a pressure resistance that withstands the internal pressure of the refrigerant, and the material cost is high and it is not economical.

In Patent Document 7, in order to use a three-layer cladding tube, the manufacturing process is complicated and the productivity and yield are also lowered, so that there is a problem that the processing cost increases.

The present invention has been made in view of the above, and an object thereof is to provide a heat transfer tube having an inner groove made of an aluminum alloy in which pin crushing is unlikely to occur even if the pipe is mechanically expanded by a mandrel. Another object of the present invention is to provide a heat exchanger tube having an inner groove made of an aluminum alloy capable of thinning, which has better corrosion resistance as a heat transfer tube that is hard to generate such pin crush.

MEANS TO SOLVE THE PROBLEM As a result of earnest examination, the present inventors discovered that the following heat exchanger solved the subject, and completed this invention.

That is, according to the present invention, a plurality of protruding fins are formed on the inner surface, and Mn: 0.8 to 1.8% by mass (hereinafter referred to as% by mass), Cu: 0.3 to 0.8%, and Si: 0.3 to 1.0%. There is provided a heat transfer tube having an inner groove made of an aluminum alloy, wherein the balance is made of Al and inevitable impurities.

According to this structure, a heat exchanger tube in which fin crushing hardly occurs can be obtained.

According to the present invention, a plurality of protruding fins are formed on the inner surface, and contain Mn: 0.8-1.8%, Cu: 0.3-0.8%, Si: 0.3-1.0%, and further Fe: 0.60% or less, Mg: It contains one or more of 0.20% or less, Zn: 0.30% or less, Cr: 0.20% or less, Ti: 0.20% or less, Zr: 0.20% or less, and the balance consists of Al and unavoidable impurities. A heat transfer pipe having an inner groove made of an aluminum alloy is provided.

According to this structure, a heat exchanger tube in which fin crushing hardly occurs can be obtained.

Moreover, according to this invention, the heat exchanger provided with any one of said heat exchanger tubes is provided.

According to this structure, since the heat exchanger tube which a fin crush does not generate | occur | produce easily is provided, the heat exchanger excellent in heat transfer performance can be obtained.

Moreover, according to this invention, the air conditioner provided with any one of said heat exchanger tubes is provided.

According to this structure, since the heat exchanger tube which a pin crush is hard to produce is provided, the air conditioner excellent in heat transfer performance can be obtained.

The heat exchanger tube having an inner groove made of the aluminum alloy of the present invention has an effect that pin crushing is unlikely to occur even if the tube is mechanically expanded by a mandrel. Alternatively, pin crushing is unlikely to occur, good corrosion resistance and thinning are possible, so that the material cost can be suppressed.

1 is a partially enlarged view of a cross fin type heat exchanger.
2 is a view showing a mandrel expansion method.
3 is an example of a roll rolling device.
4 is a schematic cross-sectional view of a tube having an inner groove.
5 is a schematic diagram showing the lead angle of the inner protruding pin.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described in detail. In addition, description is abbreviate | omitted suitably about the same content, in order to avoid repeating confusion.

Embodiment 1: Heat Transfer Tube

(1-1) component

The heat exchanger tube assumed in this embodiment is generally used for the heat exchanger for air conditioners for home use, The dimension is φ4.0-φ9.54mm in outer diameter, for example, It is 0.3 ~ 0.6mm in diameter and small in thickness. Therefore, among various aluminum alloys, Al-Mn system which has moderate strength and is relatively excellent in workability (extrusion property, PS property, rolling property) for obtaining a tube with a small diameter and a thin thickness. It is based on A3003 alloy (alloy consisting of Al, 1.0 ~ 1.5% Mn, 0.05 ~ 0.20% Cu), and increases the strength without damaging the workability by the adjustment of additive elements. Obtain an aluminum alloy that prevents crushing.

In the heat exchanger tube of the present embodiment, a plurality of protruding fins are formed on the inner surface, and Mn is 0.8 to 1.8% by mass (hereinafter, the mass% is described as%), Cu is 0.3 to 0.8%, and Si is 0.3 to 1.0. A heat transfer tube containing an inner groove made of an aluminum alloy containing%, the balance being made of Al and inevitable impurities. The heat transfer tube has an effect that fin crushing is unlikely to occur, as demonstrated in the examples below. Since the heat transfer pipe has a high pressure resistance of the pipe, it is possible to reduce the material cost due to thinning. The heat transfer tube is excellent in productivity, quality, and the like because it does not necessarily require a complicated production process or a special structure.

The heat pipe is formed with a plurality of protruding fins on the inner surface, and contains Mn: 0.8-1.8%, Cu: 0.3-0.8%, Si: 0.3-1.0%, and further Fe: 0.60% or less, Mg: 0.20 % Or less, Zn: 0.30% or less, Cr: 0.20% or less, Ti: 0.20% or less, Zr: 0.20% or less, containing one or two or more, and the balance consists of Al and unavoidable impurities. Even in the case of a heat pipe having an inner groove made of an aluminum alloy, it is believed that the same effect can be obtained.

Here, an aluminum alloy is an alloy which has Al as a main component. Content of Al in an aluminum alloy is 90 to 99.9%, for example. Content of Al is 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, or 99.9%, for example. Content of Al may exist in arbitrary two ranges of the numerical value illustrated here. As the alloy system, a 3000 alloy represented by JIS3003, 3004, or the like, or a 6000 alloy represented by JIS6061, 6063, or the like can be suitably used.

Next, the reason for component limitation of the heat exchanger tube in this embodiment is demonstrated.

Mn is a major addition element for improving strength in 3000 alloys, and solid solution in aluminum, part of which precipitates to give strength, and when the addition amount is less than 0.8%, the strength as a heat pipe is insufficient. More than 1.8%, the strength-improving effect saturates, and the amount of coarse intermetallic compound increases, leading to defects such as breakage in the tube manufacturing process. Therefore, the amount of Mn added is in the range of 0.8 to 1.8%. More preferable range is 1.0 to 1.5%.

Cu is an element which is solid-dissolved in aluminum and has the effect of further improving the strength and not impairing workability. If the added amount is less than 0.3%, the strength is insufficient to prevent the groove from crushing in mechanical expansion, and if it is more than 0.8%, the extrusion property, the PS property, and the corrosion resistance deteriorate. Therefore, Cu addition amount is taken as 0.3 to 0.8% of range. More preferable range is 0.4 to 0.6%.

When Si is contained in an Al-Mn-Cu-based alloy, it forms an intermetallic compound of Al-Mn-Si or Al-Mn-Si-Cu-based alloy, and has an effect of further improving the strength of the Al-Mn-Cu-based alloy. It is an element which does not impair workability, therefore. If the added amount is less than 0.3%, the strength is insufficient, and crushing of the grooves in mechanical expansion cannot be prevented, and if it is more than 1.0%, the extrudability, the drawing property, the roll workability, and the grain workability are deteriorated. Therefore, Si addition amount is taken as 0.3 to 1.0% of range. More preferable range is 0.4 to 0.6%.

Impurities include Fe, Mg and Zn, but these do not impair the effects of the present invention if Fe is 0.6% or less, Mg is 0.2% or less and Zn is 0.3% or less. It is more preferable that these content rates are small from a viewpoint which does not impair the effect of this invention. In addition, the lower limit of these content rates is not specifically limited, For example, 0.01, 0.001, 0.0001 or more, or 0% may be sufficient.

In addition, Ti, Cr, and Zr may be contained because of the effect of uniformly minimizing the ingot structure, but when it exceeds 0.2%, a large intermetallic compound is formed or the extrudability is lowered, so the content thereof is made 0.2% or less. Although the lower limit of these content rates is not specifically limited, For example, 0.01, 0.001, 0.0001 or more, or 0% may be sufficient.

(1-2) pin

In this embodiment, HV (Vickers hardness) may be 35 or more as the hardness of the protruding pin. This is to prevent pin crushing during expansion. In order to control the hardness, specifically, the combination of the Mn, Cu, and Si addition amounts is appropriately optimized (basically, the higher combination within the component range), and at the time of annealing, it is not usually overheated. Process control may be performed. On the other hand, if the hardness of the protruding pin is HV of 35 or more before expansion, the projection pin does not plastically deform during expansion, so that the hardness after expansion is not changed.

(1-3) Sacrificial Anticorrosive Layer

The heat transfer tube of the present embodiment is assumed to be used as a heat exchanger of an outdoor unit in a salt bath or the like on the shore, and a pure Al or Al-Zn alloy layer may be provided on the outer surface of the heat transfer tube as a sacrificial anticorrosive layer. . The heat exchanger tube of the present embodiment in which the sacrificial anticorrosive layer is formed is excellent in both of corrosion resistance and pin crushing, and thus becomes a high quality heat transfer tube.

As for the thickness of such a sacrificial anticorrosive layer, 5-30% is preferable with respect to whole thickness. If the thickness of the sacrificial anticorrosive layer is less than 5% of the total thickness, the effective period of the sacrificial anticorrosive layer in use as a heat exchanger is insufficient. If the sacrificial anticorrosive layer exceeds 30%, the strength of the heat transfer tube is reduced, making it difficult to thin. This ratio is, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30%. In addition, this ratio may be in the range of any two values illustrated here.

The component of the sacrificial anticorrosive layer may have a lower natural potential than that of the Al-Mn-Si-Cu alloy of the core material. For example, pure aluminum such as A1050 or A7072 (Al-0.8 to 1.3%). Zn alloy), such as Al-Zn alloy may be used as appropriate.

Next, the example of embodiment of the formation method of a sacrificial anticorrosive layer is demonstrated.

Combination billet in which a sacrificial alloy plate material (pure Al or Al-Zn-based alloy) is bent in a cylindrical shape on the outer side of the cylindrical billet of the Al-Mn-Si-Cu alloy in the heat transfer tube of the present embodiment. It is produced and heated to 350-600 ° C. in a heating furnace to perform a homogenization treatment. The combination billet is inserted between the extrusion die and the extruded ram nose and inserted into the container. In the state in which the extruded die and the extruded ram nose are fixed, a mandrel having an outer diameter larger than the core diameter is press-fitted, and the core is inserted into the container. Expand and exhale the air between the core and the shell. Next, the mandrel is fixed at a predetermined position, the extrusion hollow rod is advanced, and the combination billet is extruded through a die to obtain a two-layer clad extrusion tube. Next, the extruded tube is subjected to PS processing so as to have a predetermined outer diameter and thickness to obtain a smooth tube of a two-layer cladding. It is preferable to use the draw block type continuous drawing machine for the said drawing process with high productivity.

Alternatively, after the billet of the cylindrical sacrificial anticorrosive material is heated to 350 to 600 ° C., the two-layer air billet obtained by shrinking and inserting the cylindrical core hollow billet inside is extruded, and then subjected to the same PS process. It is also possible to obtain a smooth tube of the two-layer cladding.

In addition, a sacrificial anticorrosive material sheet is clad rolled on one side of the aluminum alloy core sheet to form a two-layer clad sheet, and the sheet is rolled into a tubular shape to weld a sheet bump surface to weld the two-layer cladding. It is good also as a sealing tube.

The above has described a method of forming a two-layer smooth tube in which a sacrificial anticorrosive layer is formed by clad extrusion / pushing or clad rolling, but as another method, Al-Mn-Si-Cu system in the heat transfer tube of the present embodiment. After spraying Zn on the extrusion tube (by hot extrusion or conform extrusion) of an alloy, or a drawing tube, you may employ | adopt the method of forming an Al-Zn diffusion layer by performing Zn diffusion heat processing. In this case, it is preferable to set the temperature and time of a diffusion heating process suitably, and to make a Zn diffused layer into 5 to 30% of range with respect to the total thickness. It is industrially preferable that the temperature is made into about 2 to 8 hours at 400-500 degreeC in general. On the other hand, only in the case of employing the Zn spraying method, after performing the rolling process described later, the Zn spraying and the diffusion heat treatment may be performed.

On the other hand, it is preferable to perform a preliminary softening treatment in advance on the smooth pipe in which the sacrificial anticorrosive layer is formed in order to facilitate the roll processing of the next step. In that case, it is industrially preferable that annealing conditions are 300-400 degreeC, and time is about 2 to 8 hours.

In addition, the smooth pipe described above slightly decreases in outer diameter and thickness in the rolling process of the next step. Therefore, the dimension (outer diameter, thickness) of the element pipe is set larger than the tube having the inner groove as the final product in consideration of the reduced portion.

Next, the smooth pipe is roll-rolled or roll rolled, or the like, and a pipe having an inner groove having a protruding pin is produced.

(1-4) Structure and Processing Method

The pipe having the inner groove of the present embodiment can be manufactured in various dimensions according to the use of the heat exchanger. However, when used in the home air conditioner, the diameter φ 4.0 mm or more is preferable from the viewpoint of productivity when the pipe is manufactured. From the viewpoint of downsizing / lightening of the heat exchanger, the outer diameter φ 9.54 mm or less is preferable. This outer diameter is 4.0, 5.0, 6.0, 6.35, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, or 9.54 mm, for example. The outer diameter may be in the range of any two values exemplified herein.

In terms of bottom thickness, 0.3 mm or more is preferable from the viewpoint of the pressure resistance strength, and 0.6 mm or less is preferable from the perspective of miniaturization / lightening of the heat exchanger. The bottom thickness is, for example, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, or 0.60 mm. The bottom thickness may be in the range of any two values exemplified herein.

In addition, the height H of the inner protrusion pin is 0.1 to 0.4 mm, the vertex angle α of the inner protrusion pin is 10 to 40 °, the number of the inner protrusion pin is 40 or more, and the lead angle β (inner protrusion pin) Angle formed by the longitudinal direction of the tube) is preferably 20 ° or more.

After carrying out a rolling process, you may perform an annealing softening process. This is to remove the dents in the processing introduced at the time of rolling and to facilitate the hairpin bending processing (meandering bending processing). What is necessary is just to perform an annealing for about 2 to 8 hours at 300-400 degreeC by a regular method.

The pipe having the inner groove of the present embodiment thus manufactured is brought into close contact with the insertion hole of the aluminum heat dissipation fin by expanding tube processing. For good adhesion, it is appropriate to set the clearance of the insertion hole and the heat transfer pipe so that the expansion rate (outer diameter increase rate) is about 4 to 6%. On the other hand, the expansion pipe processing can be improved by the mechanical expansion method using a mandrel, and the production efficiency can be improved by the hydraulic expansion method which imparts internal pressure to a pipe by hydraulic pressure or water pressure.

Embodiment 2: Heat Exchanger

Another embodiment of the present invention is a heat exchanger provided with a heat transfer tube according to the above embodiment. Since the heat exchanger includes a heat transfer tube which is hard to generate fin crush, the heat exchanger is excellent in heat transfer performance and excellent in efficiency. Alternatively, the heat exchanger is excellent in heat transfer performance and durability because the heat exchanger is provided with a heat transfer tube which is hard to generate fin crush and excellent in corrosion resistance.

Embodiment 3: air conditioner

Another embodiment of the present invention is an air conditioner having a heat transfer tube according to the above embodiment. Since the air conditioner is provided with a heat transfer tube which is hard to generate fin crushing, it is excellent in heat transfer performance and excellent in efficiency. Alternatively, the air conditioner is excellent in heat transfer performance and durability because the air conditioner is provided with a heat transfer tube that is hard to generate pin crush and has excellent corrosion resistance.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention, Various structures of that excepting the above are also employable.

<Examples>

Next, the present invention will be described in more detail based on examples.

The cylindrical billet of the aluminum alloy of the component composition shown in Table 1 was cast, and the extrusion pipe of outer diameter (phi) 47 mm and thickness was 3.5 mm by the indirect extrusion method. Drawing processing was performed to the said extruded tube by the draw-block type continuous drawing machine, and the drawing tube of outer diameter (phi) 10 mm and thickness was 0.45 mm was obtained.

For Nos. 8 to 14 and No. 21 to 26 where the sacrificial anticorrosive layer was formed, the cylindrical billet of the sacrificial anticorrosive material of A1050 or A7072 was heated to 450 ° C., and the cylindrical core billet of the cylindrical shape was shrunk and inserted therein to form a two-layer hollow billet. Then, this was indirectly extruded, and the drawing process was performed by the draw block type continuous drawing machine, and similarly the drawing tube of outer diameter (phi) 10 mm and thickness was 0.48 mm.

After performing the loosening softening treatment at 360 ° C. for 2 hours on the thus-obtained drawing tube, a plug having a floating plug, a rod, and a grooved plug was inserted, and the inner surface was passed through a floating die, a processing head, and a forming die. The inner surface is processed to have a groove in the outer diameter: φ7mm, bottom thickness: 0.35mm, the height of the protruding pin H: 0.22mm, the number of protruding pins 50, vertex angle α: 15 °, lead angle β: 35 ° I made a tube with a groove. On the other hand, about No8-14 and No21-26, it adjusted to the billet thickness of the sacrificial anticorrosive material in an extrusion process so that the said sacrificial anticorrosive layer might be 0.035 mm (ratio of 10% with respect to bottom thickness). In addition, an annealing softening treatment was performed at 360 ° C. for 2 hours to complete a tube having an inner groove.

In order to evaluate the characteristics of the tube having the inner grooves of the present invention and the comparative example thus obtained, the following test was conducted. The obtained results are shown in Table 2.

(a) Tensile test

In order to measure the strength of the tube having an inner groove, a tensile test based on JIS Z2241 was performed.

(b) Expansion processability

The pipe having the inner groove of the outer diameter φ 7 mm was expanded by using a forced mandrel so that the outer diameter was increased by 5%. Then, the cross section of the pipe | tube was observed, the amount of reduction of the height H of the protruding pin was measured, and the amount of pin crushing was evaluated. In order to obtain heat transfer characteristics as a heat exchanger, the fin crushing amount is preferably 0.01 mm or less. In addition, the hardness of the center part of the cross section of the protrusion pin before and after expansion pipe | tube processing was measured with the micro Vickers hardness tester.

(c) corrosion resistance

In order to evaluate external corrosion resistance, CASS test was carried out for 1500 hours in accordance with JIS Z8681 for the pipe having each inner groove. After the test, the surface corrosion products of the test tubes were removed, the corrosion state of the tubes was observed, and the external corrosion resistance was evaluated by the presence or absence of through holes.

As shown in Table 2, the pipes No1 to No14 having inner grooves made of aluminum of the present invention exhibited a reduction in height H of the protruding pins (pin crushing amount) of 0.01 mm or less, and the hardness of the protruding pin portions before expansion. The amount of pin distortion of No3 to No7 and No10 to No14 described above is 0, which is very good. Moreover, No8-No14 which provided the sacrificial anticorrosive layer does not show generation | occurrence | production of a through hole, and external corrosion resistance is favorable. Further, the tensile strength of the tube is 118 MPa or more, for example, the strength is higher than that of 97 MPa (corresponding to A3003) of Comparative Example No16, and thus the pressure resistance of the tube is also high, so that the material cost due to thinning can be reduced.

On the other hand, No15-No17 and No21-No23 which have a small amount of Mn, Cu, and Si have large distortion of the protruding pin at the time of expansion, and the intensity | strength of the tube itself is also low. On the contrary, No18 to No20 and No24 to No26 having a large amount of Mn, Cu, and Si were broken in the drawing process and the rolling process, and a pipe having an inner groove could not be produced.

In the above, this invention was demonstrated based on the Example. The above embodiments are illustrative only, and there may be various modified examples, and it will be understood by those skilled in the art that such modified examples fall within the scope of the present invention.

1: aluminum heat dissipation fin
2: heat pipe (tube with inner groove)
3: louver
4: Expansion plug (mandrel)
5: smooth tube
6: rolling plug
7: rolling roll
8: tube with inner spiral groove
9: protruding pin
10: sacrificial layer

Claims (8)

A plurality of protruding fins are formed on the inner surface and contain Mn: 0.8-1.8% by mass (hereinafter referred to as% by mass), Cu: 0.3-0.8%, Si: 0.3-1.0%, and the balance is Al and Heat transfer tube having an inner groove made of an aluminum alloy, characterized in that consisting of inevitable impurities. A plurality of protruding fins are formed on the inner surface and contain Mn: 0.8 ~ 1.8%, Cu: 0.3 ~ 0.8%, Si: 0.3 ~ 1.0%, Fe: 0.60% or less, Mg: 0.20% or less, Zn: 0.30 1% or more of Cr or less, Cr: 0.20% or less, Ti: 0.20% or less, Zr: 0.20% or less, and the balance is made of an aluminum alloy, characterized in that the balance consists of Al and unavoidable impurities. Heat pipe with inner groove. The method according to claim 1 or 2,
Heat transfer tube, characterized in that the hardness of the protruding fin is greater than HV35. The method according to claim 1 or 2,
A heat transfer tube, wherein a pure Al or Al-Zn alloy layer is formed on the outer surface as a sacrificial anticorrosive material. The method according to claim 1 or 2,
Heat pipe of which the outer diameter of the heat pipe is 4.0 ~ 9.44mm. The method according to claim 1 or 2,
Heat transfer tube of which the bottom thickness of the heat transfer tube is 0.3 ~ 0.6mm. The heat exchanger provided with the heat exchanger tube of Claim 1 or 2. The air conditioner provided with the heat exchanger tube of Claim 1 or 2.

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