JP2758536B2 - Welded copper alloy pipe with inner groove - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internally grooved welded copper alloy tube used as a heat exchanger tube or the like for a heat exchanger, and more particularly to an improvement for improving processing characteristics.

[0002]

2. Description of the Related Art In general, as a heat exchanger tube for a heat exchanger, a seamless copper tube with an inner groove made of pure copper such as oxygen-free copper or phosphorous deoxidized copper is often used from the viewpoint of thermal conductivity. When these heat transfer tubes are used in an air conditioner or the like, in order to enhance the heat radiation and heat absorption effects, an aluminum fin having a through hole is passed through the outer periphery of the heat transfer tube, and then expanded through a plug in the heat transfer tube to fix the aluminum fin. Pipe expansion is performed.
Further, in order to connect the heat transfer tubes, a flare process for expanding the ends of the heat transfer tubes and a refrea process for expanding the flared portions again are sequentially performed.

[0003] In recent years, the demand for downsizing and high performance of heat exchangers has been increasing. Therefore, the heat transfer tubes used for the heat exchangers have a uniform and thin wall thickness, and a heat transfer medium such as Freon. Good evaporation and condensation performance is desired. However, in the seamless copper pipe with an inner groove, the uneven thickness is caused in a processing step, which may cause a crack during a refrea processing.In addition, a thinner wall and a smaller diameter are formed in order to form an inner groove by a drawing process. However, it was difficult to meet the above-mentioned demand.

[0004] Therefore, instead of a general seamless heat transfer tube, a complicated groove can be formed at the stage of a metal strip, so that good evaporation / condensation performance can be easily provided and the inner surface groove having a uniform material thickness. Welded copper tubes are beginning to be used extensively. In such a welded pipe, like the seamless heat transfer pipe,
As the material, pure copper such as oxygen-free copper or phosphorus deoxidized copper having high conductivity (in the case of copper and copper alloys, the conductivity that can be easily measured can be used as a measure of thermal conductivity) is often used. ing.

[0005]

According to the current standard of use of many users, even with the pure copper inner grooved welded copper pipe, there is almost no cracking problem during processing, and sufficient reliability can be obtained. Have been. However, when the diameter and thickness of the heat transfer tube are further reduced in the future and more severe processing conditions are adopted, the pure copper welded tube is recrystallized in the vicinity of the welded portion due to the heat effect at the time of welding. Occurs, and the crystal grain size tends to increase, and cracking may occur from the welded portion if the refrea processing conditions are strict.

Therefore, in the future, it is expected that it is necessary to further improve the refreaability of the welded pipe with an inner groove. The present invention has been made in view of the above circumstances, and it is an object of the present invention to further improve the refreaability in an internally grooved welded copper pipe.

[0007]

Means for Solving the Problems The present inventors have found that, compared to welded copper pipes having an inner surface groove such as oxygen-free copper and phosphorus deoxidized copper, the present invention has an excellent refining workability, and has a conductive property in relation to thermal conductivity. Rate 7
Research was conducted to develop a welded copper alloy tube with an inner groove made of a copper alloy material of 0% IACS or more. As a result, it is based on oxygen-free copper and phosphorous deoxidized copper, with Fe, Cr,
Mn, Ni, Ag, Zn, Sn, Al, Si, Pb, M
g, Te, Zr, B, and one or more elements selected from the group consisting of Ti and 0.01 to 0.5% by weight in total.
A copper alloy welded copper alloy pipe with an inner groove having a composition comprising the balance of Cu and inevitable impurities has a conductivity of 70% IACS or more, and is also stronger in strength than a conventional welded copper pipe with an inner groove. It has been found that there is little difference in the crystal grain size between the vicinity and the peripheral portion of the welded portion, and that it is excellent in refreaability.

The present invention has been made based on the above findings. The welded copper alloy pipe with an inner groove according to the present invention is made of anoxic copper or phosphorus-deoxidized copper containing 0.005 to 0.05% by weight of P. On the other hand, Fe, Cr, Mn, Ni, Ag, Zn,
It consists of a component containing 0.01 to 0.5% by weight in total of one or two or more elements selected from Sn, Al, Si, Pb, Mg, Te, Zr, B and Ti. Is characterized in that the crystal grain size is within twice the crystal grain size of the portion other than the welded portion.

Next, the reason why the composition of the welded copper alloy pipe with an inner groove according to the present invention is limited as described above will be described. Fe,
Cr, Mn, Ni, Ag, Zn, Sn, Al, Si, P
Each component of b, Mg, Te, Zr, B and Ti forms a solid solution in a pure copper or phosphorus deoxidized copper matrix or forms a compound phase, and suppresses coarsening of crystal grains due to high temperature heating. It has the effect of increasing the strength of the copper alloy material and improving the refining processability. However, if the total amount of the additional elements is less than 0.01% by weight, the above effect cannot be obtained.

On the other hand, the total amount of the above-mentioned additional elements is 0.5% by weight.
If it exceeds, the conductivity will be less than 70% IACS, and the heat transfer characteristics will often deteriorate. In addition, the unhealthyness of the welded portion due to entrapment of oxides and the like will increase, and the connection between the welded portion and the other portions will be increased. The strength difference is increased, and the unevenness of the pipe shape after the pipe expansion processing and the refrea processing is increased, which is not preferable. For this reason, the total amount of each of the above components was determined to be 0.01 to 0.5% by weight.

The inner grooved welded copper alloy tube is used as a heat transfer pipe for a heat exchanger, and therefore, the higher the conductivity is, the better. However, if the conductivity is 70% IACS or more, the phosphorous deoxidized copper (85% IACS or less), there is no problem in practical use, and this difference in conductivity (that is, heat conductivity) is
The shape of the inner surface groove of the heat transfer tube and other settings can sufficiently compensate for it. Therefore, the lower limit of the electrical conductivity of the copper alloy material of the copper alloy tube with an inner groove according to the present invention was set to 70% IACS.

Further, if the crystal grain size of the welded portion is less than twice the crystal grain size of the other portions, the influence on the refining workability will not be so large, so that the difference between the two crystal grain sizes is not more than 2 times. It is determined to be within double.

[0013]

Next, an embodiment of a welded copper alloy pipe with an inner groove according to the present invention will be described in detail. Copper alloys of the compositions shown in Tables 1 to 4 were semi-continuously cast using a water-cooled mold,
After hot rolling at a temperature of ９950 ° C., surface grinding was performed to produce a 9 mm thick plate. This hot-rolled sheet with a thickness of 0.
Cold-rolled to 8 mm, 1 at 250-550 ° C
After the time sintering, it was cold-rolled to a thickness of 0.4 mm at a processing rate of 50%, and further subjected to sintering at a temperature of 250 ° C to 550 ° C for 1 hour.

Each of the obtained copper alloy strips is cut at a width of 31 mm by a slitter, embossed by a grooved rolling roll, and has a crest 2 and a groove 3 shown in FIG. After forming the sheet material, the sheet material is set in the ERW device with the groove forming surface facing the inner surface side, and the sheet material is rolled in the width direction through the drive roll and the idler in multiple stages, and finally, Then, both side edges of the strip material were welded and formed into a tubular shape. In FIG. 1, reference numeral 4 denotes a welded portion, which is formed to extend in the axial direction of the tube (for a method of manufacturing a welded tube having an inner groove, see Japanese Patent Application Laid-Open No. 4-157636).

The outer diameter of the formed tube is 9.52 by drawing.
mm, and finally subjected to refining for 1 hour at a temperature of 250 ° C. to 550 ° C., and the content of the inner grooved welded copper alloy pipe of Examples 1 to 15 according to the present invention and the content of the additive element is The welded copper alloy tubes with inner grooves of Comparative Examples 1 to 4 which were out of the range of the present invention were produced. On the other hand, welded copper pipes with inner surface grooves of Comparative Examples 5 and 6 were produced in exactly the same manner as described above, using oxygen-free copper and phosphorus deoxidized copper, respectively. In addition, a commercially available seamless copper tube made of phosphorus-deoxidized copper having the same dimensions and being commercially available was used as Comparative Example 7.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

The following tests and measurements were performed on the heat transfer tubes of Examples 1 to 15 and Comparative Examples 1 to 7. Table 5 shows the results.

(1) Tensile test A tensile test was performed by a method according to JIS-Z2241 and JIS-Z2201, and the tensile strength and elongation were measured. (2) Conductivity Measurement The conductivity of each copper alloy strip before embossing was measured by the method of JIS-H0505.

(3) Measurement of crystal grain size ratio The difference in crystal grain size between the welded portion (within 0.15 mm from the center of the welded portion) and the other portion (the portion not affected by heat during welding) is as follows. The grain size at a portion where a crystal grain is large is represented by a numerator, and the grain size at a portion where a crystal grain is small is a denominator.

(4) Refrea workability Since the refrea work cracking hardly occurs in the currently adopted standard, the criterion is made stricter, and the inner surface grooves of the same dimensions in Examples 1 to 15 and Comparative Examples 1 to 7 are used. For each of the 20 seamless copper tubes, a conical plug was inserted from the end, and a spreading test was performed at a expansion ratio of 1.70 to determine the crack occurrence rate (%).

[0024]

[Table 5]

As is clear from the results shown in Table 5,
The welded copper alloy pipes with inner grooves of Examples 1 to 15 according to the present invention are less likely to have a large crystal grain size due to welding heat as compared with Comparative Examples 1 to 7, and have good spread test results. , Excellent in refrea workability. Nevertheless, there is almost no difference in electrical conductivity (thermal conductivity) and the strength is sufficiently high.

[0026]

As described above, according to the welded copper alloy pipe with an inner surface groove of the present invention, even when refrearing or the like having a large diameter expansion rate is performed, cracks are less likely to occur at the pipe end, and the heat transfer pipe And the manufacturing yield can be improved. In addition, as the processing characteristics of the heat transfer tube are improved, the diameter and the thickness of the heat transfer tube can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a welded copper alloy pipe with an inner surface groove according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internally grooved welded copper alloy pipe 2 Crest 3 Groove 4 Weld

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyosu Masukawa 128-7 Ogimachi, Aizuwakamatsu-shi, Fukushima Prefecture Mitsubishi Shindo Copper Co., Ltd. Wakamatsu Works (72) Inventor ▲ Sukumo ▼ Shun Tadashi ▲ Green ▼ 128-7, Ogimachi Mitsubishi Shindo Copper Co., Ltd. Wakamatsu Works (56) References JP-A-52-156719 (JP, A) JP-A-3-106206 (JP, U) JP-B-58-39900 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) C22C 9/00-9/10 F28F 1/40

Claims (2)

(57) [Claims] 1. A sheet material is rolled into a tube and its both edges are butted together.
A welded copper alloy pipe with an inner groove welded together ,
Cr, Mn, Ni, Ag, Zn, Sn, Al, Si, P
b, Mg, Te, Zr, B, and one or more elements selected from the group consisting of Ti and 0.01 to 0.5% by weight in total, the balance being Cu and unavoidable impurities, and the crystal grains of the welded portion An inner grooved welded copper alloy tube having a diameter within two times the crystal grain size of a portion other than the welded portion. 2. A sheet material is rolled into a tubular shape and its side edges are butted together.
A welded copper alloy tube with an inner groove, which is welded together, containing 0.005 to 0.05% by weight of P, and further containing Fe, Cr,
Mn, Ni, Ag, Zn, Sn, Al, Si, Pb, M
g, Te, Zr, B and one or more elements selected from the group consisting of Ti and 0.01 to 0.5% by weight in total, the balance being Cu and unavoidable impurities, and the grain size of the welded portion is An internally grooved welded copper alloy pipe having a grain size within twice the grain size of a portion other than a welded portion.