WO2012128240A1

WO2012128240A1 - Seamless tube, coil, level wound coil, method for manufacturing level wound coil, cross-fin-tube-type heat exchanger, and method for manufacturing cross-fin-tube-type heat exchanger

Info

Publication number: WO2012128240A1
Application number: PCT/JP2012/056966
Authority: WO
Inventors: 勝政平工; 正明小平; 聖健澤
Original assignee: 株式会社住軽伸銅
Priority date: 2011-03-23
Filing date: 2012-03-19
Publication date: 2012-09-27
Also published as: CN103415643B; KR101385801B1; JPWO2012128240A1; JP5132845B2; KR20130105755A; MY156255A; CN103415643A

Abstract

A seamless tube for a heat transfer tube for a cross-fin-tube-type heat exchanger, which is characterized in that the material for the seamless tube is phosphorus deoxidized copper, the ratio of the thickness (mm) of the seamless tube to the outer diameter (mm) of the seamless tube (i.e., t/D) is 0.040 or less, and the seamless tube has a tensile strength (σ_B) of 245 MPa or more, a 0.2% offset yield strength (σ_0.2) of 140 MPa or less and an elongation (δ) of 40% or more. It becomes possible to provide a seamless tube made of phosphorus deoxidized copper, which has high strength and can be bent in a hairpin shape in a normal manner.

Description

Seamless tube, coil, level-wound coil, method for manufacturing level-wound coil, cross-fin tube type heat exchanger, and method for manufacturing cross-fin tube type heat exchanger

The present invention relates to a seamless pipe made of phosphorous-deoxidized copper used for heat transfer pipes or refrigerant pipes for air conditioner heat exchangers, refrigerators and the like.

Conventionally, heat pipes for air conditioners such as room air conditioners and packaged air conditioners, and heat transfer pipes or refrigerant pipes for refrigerators, etc., have been adopted with many seamless pipes, and various physical properties such as strength, workability, and heat transfer properties. In addition, a phosphorus-deoxidized copper pipe (JIS C1220T) balanced in material and processing cost has been used.

In recent years, in these heat exchangers, it has become necessary to reduce the thickness of seamless pipes due to demands for weight reduction or cost reduction, for example, International Publication No. 2008/041777 (Patent Document 1), Japanese Unexamined Patent Publication No. 2003-268467 (Patent Document 2) discloses a seamless pipe made of a copper alloy having high strength.

International Publication No. 2008/041777 (Claims) JP 2003-268467 A (Claims)

However, heat exchangers for air conditioners such as room air conditioners, packaged air conditioners, refrigerators, etc. in which seamless pipes made of copper alloy as described in Patent Document 1 or 2 are used are discarded. However, when disassembling the equipment and recycling each material, the copper alloy seamless pipes are limited in their recycling destination due to the presence of alloying elements added in addition to copper, making them valuable as recycling materials. It will be lower. In addition, when manufacturing seamless pipes made of copper alloy, when the waste generated in the manufacturing process is redissolved and used, the use destination is restricted and the melting furnace is contaminated by the added alloying elements. Occurs.

For this reason, there is a demand to reduce the thickness of the copper dephosphorized copper while adopting phosphorous deoxidized copper as the copper material constituting the seamless pipe, while increasing the pressure strength, and increasing the strength of the phosphorous deoxidized copper. It is desired.

For phosphorus deoxidized copper, it is not possible to use means for solid solution strengthening or precipitation strengthening like copper alloys, but it has been conventionally practiced to increase the strength by means of work hardening. For example, in the final process of processing a copper tube, it has been conventionally performed to add a predetermined degree of processing by drawing (drawing).

However, in the case of a seamless tube for a heat transfer tube of a cross fin tube type heat exchanger, the strength is improved by work hardening when performing strong processing called hairpin bending (U bending) in the process of assembling to the heat exchanger. When a thin-walled phosphorus-deoxidized copper seamless pipe is used, the yield strength is about 200 MPa and the elongation is less than 30%, which causes a problem that normal bending cannot be performed. Specifically, wrinkles are generated in the inner part of the bend, the bend is flattened, and the value in appearance quality is significantly impaired. In extreme cases, breakage occurs. In particular, in the current situation where the diameter and thickness of the heat transfer tube are reduced and the hairpin bending pitch is small and the hairpin bending conditions are severe, it is increasingly difficult to perform normal hairpin bending.

Therefore, the present invention is to provide a seamless tube made of phosphorus-deoxidized copper that has high strength and can perform hairpin bending normally.

As a result of intensive studies to solve the problems in the prior art, the present inventors have specified the total degree of work in cold working in the process of manufacturing seamless pipes by processing phosphorous deoxidized copper. the range, the holding temperature of the final annealing by a specific range, the tensile strength (sigma _B) despite the high 0.2% proof stress (sigma _0.2) is low, elongation ( A seamless pipe having a high δ) is obtained, and the tensile strength (σ _B ) is set to a specific range, and the 0.2% proof stress (σ _0.2 ) and the elongation (δ) are set to a specific range. The present seamless pipe has been found to be able to bend hairpin normally despite its high strength, and has completed the present invention.

That is, the present invention (1) is a seamless tube for a heat transfer tube of a cross fin tube type heat exchanger,
The material of the seamless pipe is phosphorus deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe is 0.040 or less,
The seamless pipe has a tensile strength (σ _B ) of 245 MPa or more,
0.2% proof stress (σ _0.2 ) is 140 MPa or less,
Elongation (δ) is 40% or more,
A seamless tube characterized by the above is provided.

Moreover, this invention (2) is a coil produced by winding a seamless pipe,
The material of the seamless pipe wound around the coil is phosphorus deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the coil is 0.040 or less,
The tensile strength (σ _B ) of the seamless pipe wound around the coil is 245 MPa or more,
0.2% proof stress (σ _0.2 ) is 130 MPa or less,
Elongation (δ) is 40% or more,
The coil characterized by this is provided.

Further, the present invention (3) is a level-wound coil in which the coil is produced by arranging multiple layers in a cylindrical shape.
The material of the seamless pipe wound around the level wound coil is phosphorous deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the level wound coil is 0.040 or less,
The tensile strength (σ _B ) of the seamless pipe wound around the level wound coil is 245 MPa or more,
0.2% proof stress (σ _0.2 ) is 130 MPa or less,
Elongation (δ) is 40% or more,
A level-wound coil characterized by the above is provided.

In the present invention (4), the material is phosphorous deoxidized copper, the ratio (t / D) of the thickness (mm) to the outer diameter (mm) is 0.040 or less, and the tensile strength (σ _B ) is 245 MPa or more, 0.2% proof stress (σ _0.2 ) is 120 MPa or less, and a level-wound coil-producing seamless pipe having an elongation (δ) of 40% or more is aligned in a cylindrical shape. The present invention provides a method for producing a level-wound coil that is wound to produce a level-wound coil.

In addition, the present invention (5) comprises hairpin bending the seamless pipe of the present invention (1), the coil of the present invention (2), or the seamless pipe unwound from the level wound coil of the present invention (3), and aluminum fins. The cross fin tube heat exchanger obtained by assembling to is provided.

Further, the present invention (6) is a method of bending the seamless tube unrolled from the seamless tube of the present invention (1), the coil of the present invention (2) or the level wound coil of the present invention (3) by hairpin bending, A cross fin tube type heat exchanger is obtained by assembling to a cross fin tube type heat exchanger.

According to the present invention, it is possible to provide a seamless pipe made of phosphorus-deoxidized copper which has high strength and can perform hairpin bending normally.

It is a schematic diagram which shows the vicinity of the hairpin bending part of the seamless pipe in a cross fin tube type heat exchanger. It is typical sectional drawing which shows the groove shape of an inner surface grooved pipe | tube.

The seamless tube of the present invention is a seamless tube for a heat transfer tube of a cross fin tube type heat exchanger,
The material of the seamless pipe is phosphorus deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe is 0.040 or less,
The seamless pipe has a tensile strength (σ _B ) of 245 MPa or more,
0.2% proof stress (σ _0.2 ) is 140 MPa or less,
Elongation (δ) is 40% or more,
It is a seamless tube characterized by.

The seamless tube of the present invention is a seamless tube for a heat transfer tube of a cross fin tube type heat exchanger. That is, the seamless pipe of the present invention is a seam used for manufacturing a cross fin tube type heat exchanger by being hairpin bent and assembled to a fin material when the cross fin tube type heat exchanger is manufactured. There is no pipe.

The seamless pipe of the present invention is made of phosphorous deoxidized copper. The phosphorus-deoxidized copper according to the seamless pipe of the present invention does not contain various alloy components, and the chemical composition is defined in JIS H3300 C1220 or C1201, so that the phosphorus-deoxidized copper according to the seamless pipe of the present invention. The P content of the acid copper is 0.004 to 0.040 mass%, preferably 0.015 to 0.030 mass%, and the Cu content is 99.90 mass% or more. And since the seamless pipe of this invention is a product made from phosphorus deoxidation copper, it is excellent in recyclability.

The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe of the present invention is 0.040 or less, preferably 0.020 to 0.040, particularly preferably 0.030 to 0. .038. When t / D is in the above range, the seamless pipe can sufficiently cope with the reduction in diameter and thickness.

The outer diameter D (mm) of the seamless pipe of the present invention is 3 to 8 mm, particularly preferably 4 to 7 mm. The wall thickness t (mm) of the seamless pipe of the present invention is determined by the outer diameter (D) of the seamless pipe and the ratio of the wall thickness to the outer diameter (t / D). 0.15 to 0.30 mm is preferable.

The tensile strength (σ _B ) of the seamless pipe of the present invention is 245 MPa or more, preferably 245 to 265 MPa. When the seamless pipe has a tensile strength in the above range, a sufficient pressure resistance can be obtained even by thinning. On the other hand, when the tensile strength of the seamless pipe is less than the above range, the pressure resistance is insufficient when the thickness is reduced. If the tensile strength of the seamless pipe exceeds 265 MPa, it becomes difficult to make the 0.2% proof stress (σ _0.2 ) 140 MPa or less and the elongation (δ) 40% or more.

The 0.2% proof stress (σ _0.2 ) of the seamless pipe of the present invention is 140 MPa or less, preferably 80 to 120 MPa. The elongation (δ) of the seamless pipe of the present invention is 40% or more, preferably 40 to 55%. When the 0.2% proof stress (σ _0.2 ) and the elongation (δ) of the seamless pipe are in the above ranges, the hairpin bending workability is improved. On the other hand, when the 0.2% proof stress of the seamless pipe exceeds the above range and the elongation is below the above range, strong processing with a small bending pitch P (for example, hairpin processing with a bending pitch P of 22 mm or less shown in FIG. 1) is performed. It becomes difficult to perform, and at the time of hairpin bending, wrinkles are generated in the inner part of the bend, the tube is flattened, or is damaged in an extreme case. Also, if the 0.2% proof stress of the seamless pipe is less than 80 MPa, problems such as buckling and clogging are likely to occur in the bending process because the degree of bending and bending of the material increases before being subjected to bending. Become. In addition, the bending pitch P is a distance between the tube axes (code | symbol 1) of the 2 seamless pipes arranged in parallel substantially by hairpin bending, as shown in FIG.

Examples of the seamless pipe according to the present invention include an inner surface smooth tube (bearing tube) in which no inner surface groove is formed and an inner surface grooved tube in which an inner surface groove is formed. In the case of an inner smooth tube, the outer diameter D of the seamless tube is the outer diameter of the tube in a cross section when the seamless tube is cut by a plane perpendicular to the tube axis direction, and the wall thickness t of the seamless tube. Is the thickness of the pipe in a cross section when the seamless pipe is cut along a plane perpendicular to the pipe axis direction. In the case of an internally grooved pipe, the outer diameter D of the seamless pipe is the outer diameter of the pipe in a cross section when the seamless pipe is cut by a plane perpendicular to the pipe axis direction. As shown in FIG. 2, the wall thickness t is the thickness of the pipe (bottom wall thickness) at the deepest position s of the inner groove in the cross section when the seamless pipe is cut along a plane perpendicular to the pipe axis direction. It is.

The method for producing the seamless pipe of the present invention will be described. The manufacturing method of the seamless pipe of the first aspect of the present invention is a manufacturing method in the case where the seamless pipe is an inner surface smooth pipe. Moreover, the manufacturing method of the seamless pipe of the 2nd form of this invention is a manufacturing method in case a seamless pipe is an internal grooved pipe.

The method for producing a seamless pipe according to the first aspect of the present invention includes a casting process for casting phosphorous deoxidized copper, a hot extrusion process, and a cold working with a total working degree of 99.5% or more in terms of a cross-section reduction rate. A cold working process for performing a final annealing process in which annealing is performed at a holding temperature of 360 to 600 ° C. is performed in this order, and an intermediate annealing process is not performed between the hot extrusion process and the final annealing process. It is a manufacturing method.

In the seamless pipe manufacturing method of the first aspect of the present invention, a casting process, a hot extrusion process, a cold working process, and a final annealing process are performed in this order. In addition, performing these in order does not mean that a hot extrusion process is performed immediately after the casting process, a cold working process is performed immediately after the hot extrusion process, and a final annealing process is performed immediately after the cold working process. It means that a hot extrusion process is performed after the casting process, a cold working process is performed after the hot extrusion process, and a final annealing process is performed after the cold working process.

In addition, the seamless pipe manufacturing method according to the second aspect of the present invention includes a casting process for casting phosphorous deoxidized copper, a hot extrusion process, and a cold working with a total workability of 99.8% or more in terms of the cross-section reduction rate. A cold working process in which hot working is performed, an intermediate annealing process (A), a rolling process process, and a final annealing process in which annealing is performed at a holding temperature of 360 to 600 ° C. are sequentially performed, and a hot extrusion process and an intermediate annealing process are performed. This is a seamless pipe manufacturing method in which no other intermediate annealing treatment is performed between the treatment (A).

In the seamless pipe manufacturing method of the second aspect of the present invention, a casting process, a hot extrusion process, a cold working process, an intermediate annealing process (A), a rolling process process, and a final annealing process, , In order. In addition, performing these in order means that a hot extrusion process is performed immediately after the casting process, a cold processing process is performed immediately after the hot extrusion process, an intermediate annealing process (A) is performed immediately after the cold processing process, and an intermediate annealing process. The rolling process is performed immediately after the process (A), and the final annealing process is not performed immediately after the rolling process, but the hot extrusion process is performed after the casting process, and the cold processing process is performed after the hot extrusion process. Indicates that the intermediate annealing process (A) is performed after the cold working process, the rolling process process is performed after the intermediate annealing process (A), and the final annealing process is performed after the rolling process process.

From the casting process to the cold working process of the seamless pipe manufacturing method of the first aspect of the present invention and from the casting process to the cold working process of the seamless pipe manufacturing method of the second aspect of the present invention. The same.

The casting process according to the method for manufacturing a seamless pipe according to the first aspect of the present invention and the method for manufacturing the seamless pipe according to the second aspect of the present invention involves melting and casting in accordance with a conventional method, and a predetermined element is a predetermined element. It is a step of obtaining a billet that is blended by content. In the casting process, for example, copper ingot, copper scrap, Cu-P master alloy, etc. are blended and the components are adjusted so that the P content becomes a predetermined content, and then a high frequency melting furnace or the like is used. And billet is cast.

In the method for manufacturing a seamless pipe according to the first aspect of the present invention and the method for manufacturing the seamless pipe according to the second aspect of the present invention, heat for extruding a billet obtained by performing a casting process is then performed. Inter-extrusion process is performed. In the hot extrusion process, the billet is heated at a predetermined temperature before hot extrusion, and then hot extrusion is performed. Hot extrusion is performed by mandrel extrusion. That is, hot extruding is performed with a mandrel inserted into a billet that has been previously perforated cold before heating, or a billet that has been perforated hot before extrusion to obtain a seamless hot extruded element tube. .

The seamless hot-extrusion element tube obtained by performing the hot extrusion process is quickly cooled after the hot extrusion process. The cooling is performed by extruding the seamless hot-extrusion element tube into water or by introducing the seamless hot-extrusion element tube after hot extrusion into water.

In the method for producing a seamless pipe according to the first aspect of the present invention and the method for producing the seamless pipe according to the second aspect of the present invention, the seamless extruded element pipe after cooling is then cold-worked. A cold working process is performed to reduce the outer diameter and thickness. Cold working is cold drawing (drawing) or a combination of cold rolling with a tube laser and cold drawing (drawing). In the cold working process, cold working such as rolling and drawing can be performed a plurality of times. In the method for manufacturing a seamless pipe according to the first aspect of the present invention and the method for manufacturing a seamless pipe according to the second aspect of the present invention, the cold working step refers to all of the cold working.

After the cold working step, the method for manufacturing the seamless pipe according to the first aspect of the present invention and the method for manufacturing the seamless pipe according to the second aspect of the present invention are different from each other.

In the seamless pipe manufacturing method of the first aspect of the present invention, after the cold working step, the final annealing treatment of the seamless bare tube after the cold working obtained by performing the cold working step is performed. The holding temperature and holding time of the final annealing treatment are appropriately selected so that the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ) and elongation (δ) of the seamless pipe are within the predetermined ranges. Is done. In particular, with respect to the holding temperature, a temperature of “recrystallization temperature (° C.) × 0.7” to “recrystallization temperature (° C.) × 0.8” is selected in the range of 360 to 600 ° C. For example, when the recrystallization temperature is 600 ° C., a temperature of 420 to 480 ° C. is selected.

And in the manufacturing method of the seamless pipe of the 1st form of this invention, an intermediate annealing process is not performed between a hot extrusion process and a final annealing process, but the total workability ( (Section reduction rate) is 99.5% or more. In addition, the total degree of cold working process is the machining of the seamless tube after the last cold working performed in the cold working process for the first seamless steel pipe before the cold working performed in the cold working process. It indicates the degree and is represented by the cross-sectional reduction rate shown in the following formula (1).
Cross-sectional reduction rate (%) = ((cross-sectional area before processing of pipe−cross-sectional area after processing of pipe) / (cross-sectional area before processing of pipe)) × 100 (1)
For example, in the cold working process, when cold rolling is performed a plurality of times and then cold drawing is performed a plurality of times, “cross-sectional reduction rate (%) = ((cross-sectional area before the first cold rolling of the tube −Cross sectional area after the last cold drawing of the tube) / (Cross sectional area before the first cold rolling of the tube)) × 100 ”.

In the first method for producing a seamless pipe of the present invention, after performing the hot extrusion process and before performing the final annealing process, the intermediate annealing process is not performed, and the total processing degree of the cold working process is not performed. Is within the above range, and the holding temperature of the final annealing treatment is within the above range, the tensile strength (σ _B ) of the seamless pipe obtained by final annealing is 245 MPa or more, preferably 245 to 265 MPa. The 2% proof stress (σ _0.2 ) can be 140 MPa or less, preferably 80 to 120 MPa, and the elongation (δ) can be 40% or more, preferably 40 to 55%.

Thus, the seamless pipe of the present invention can be obtained by performing the seamless pipe manufacturing method of the first aspect of the present invention.

In the method for producing a seamless pipe according to the second aspect of the present invention, the cold-worked seamless pipe obtained by performing the cold-working process subsequent to the cold-working process is subjected to 450 to 600 ° C. An intermediate annealing process (A) is performed by heating at the holding temperature. By performing the intermediate annealing process (A), the rolling process in the rolling process is facilitated. In the seamless pipe manufacturing method of the second aspect of the present invention, after the intermediate annealing process (A) is performed, no other heat treatment is performed until the rolling process step is performed. That is, the intermediate annealing process (A) is a heat treatment before the rolling process.

In the seamless pipe manufacturing method according to the second aspect of the present invention, a rolling process step of rolling the seamless pipe after the intermediate annealing treatment (A) is then performed. The rolling process is a process of forming a groove on the inner surface of the pipe material. The rolling process is performed by forming a spiral groove on the outer surface of the seamless pipe after the intermediate annealing (A). This is done by placing the formed plug and pressing it from the outside of the tube with a plurality of rolling balls rotating at high speed to transfer the groove of the formed plug to the inner surface of the tube. Moreover, after performing an intermediate annealing process (A), after performing a diameter reduction process, a rolling process process is performed.

In the seamless pipe manufacturing method of the second aspect of the present invention, a final annealing process is then performed on the internally grooved pipe after the rolling process obtained by performing the rolling process. The holding temperature of the final annealing treatment is a temperature of 360 to 600 ° C. The processing time for the final annealing treatment is appropriately selected so that the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe are within a predetermined range. The

And in the manufacturing method of the seamless pipe of the 2nd form of this invention, it does not perform heat processing, such as another intermediate annealing process, between a hot extrusion process and an intermediate annealing process (A). By setting the total processing degree (cross-sectional reduction rate) of the processing steps to 99.8% or more and keeping the holding temperature of the final annealing treatment within the above range, the tensile strength of the seamless pipe obtained by performing the final annealing treatment ( σ _B ) is 245 MPa or more, preferably 245 to 265 MPa, 0.2% proof stress (σ _0.2 ) is 140 MPa or less, preferably 80 to 120 MPa, and elongation (δ) is 40% or more, preferably 40 to 55. %. Note that the total degree of cold working process is the processing of the seamless element tube after the cold working performed last in the cold working process for the first seamless element tube performed before the cold working process. Degree (degree (1)).

Thus, the seamless pipe of the present invention can be obtained by performing the method for producing the seamless pipe of the second aspect of the present invention.

If the seamless tube is an internally grooved tube, it is possible to maintain both the heat transfer performance and the bending workability of the tube by setting the dimensional parameters of the internal groove within the following range, preferable.
・ When fin height is h (mm) and wall thickness (bottom wall thickness) is t (mm),
h / t is 0.50 to 1.2
・ When lead angle is θ (°) and fin apex angle is α (°)
θ / α is 0.70 or more Note that the fin height h, the wall thickness (bottom wall thickness) t, and the fin apex angle α are denoted by symbols h, t, and α in FIG. The lead angle θ is an inclination angle of the inner surface groove with respect to the tube axis direction of the seamless pipe.

The seamless pipe is usually wound in a coil shape to form a coil. Such a coil, that is, the coil of the present invention is a coil produced by winding a seamless tube,
The material of the seamless pipe wound around the coil is phosphorus deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the coil is 0.040 or less, preferably 0.020 to 0.040, particularly preferably 0. .030-0.038,
The tensile strength (σ _B ) of the seamless pipe wound around the coil is 245 MPa or more, preferably 245 to 265 MPa,
0.2% proof stress (σ _0.2 ) is 130 MPa or less, preferably 80 to 120 MPa,
Elongation (δ) is 40% or more, preferably 40 to 55%,
It is a coil characterized by this.

In particular, in the manufacture of a cross fin tube type heat exchanger, the seamless tube is usually unwound from the coil wound with the seamless tube, and the unwound seamless tube is subjected to hairpin bending, but the coil is cylindrical. It is often a level-wound coil that is wound in multiple layers. That is, the seamless pipe used for the cross fin tube type heat exchanger is often a seamless pipe unwound from the level wound coil.

The level wound coil is a bobbin in which seamless pipes are aligned and wound in a cylindrical shape, and the first layer, the second layer, the third layer, etc. wound in a cylindrical shape from the inner surface side of the cylindrical shape. In order from the nth layer, the multilayered layers are wound up to the final nth layer on the outer surface of the cylindrical shape. The level wound coil includes a level wound coil in which the seamless tube is unwound from the inner surface side, and a level wound coil in which the seamless tube is unwound from the outer surface side. Examples of the level wound coil in which the seamless tube is unwound from the outer surface side include a level wound coil disclosed in FIG. 11 of JP-A-2002-370869. Further, examples of the level wound coil in which the seamless pipe is unwound from the inner surface side include a level wound coil disclosed in FIG. 14 of JP-A-2002-370869.

In the level-wound coil, when manufacturing a cross fin tube heat exchanger, the seamless pipe is unwound from the inner or outer surface side of the level-wound coil, but when the seamless pipe is unwound from the level-wound coil. Since seamless hardening is added to the seamless pipe by extending the pipe, the 0.2% proof stress of the seamless pipe after being unwound becomes the 0.2% proof stress of the seamless pipe before being unrolled. Compared to increase. Therefore, the 0.2% proof stress of the seamless pipe wound around the level-wound coil (the seamless pipe before being unwound from the level-wound coil) is a hairpin bending process when manufacturing a cross fin tube type heat exchanger. Must be lower than the 0.2% proof stress of the seamless pipe (seamless pipe after being unwound from the level wound coil). Therefore, the level wound coil must be designed so that the 0.2% proof stress (σ _0.2 ) of the seamless pipe wound is taken into account in the increment when unwinding.

Such a level-wound coil, i.e., the level-wound coil of the present invention, is a level-wound coil produced by aligning multiple layers of seamless tubes,
The material of the seamless pipe wound around the level wound coil is phosphorous deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the level wound coil is 0.040 or less,
The tensile strength (σ _B ) of the seamless pipe wound around the level wound coil is 245 MPa or more,
0.2% proof stress (σ _0.2 ) is 130 MPa or less and elongation (δ) is 40% or more,
Is a level-wound coil.

In the level wound coil of the present invention, the material of the seamless tube wound around the level wound coil is phosphorous deoxidized copper. The phosphorous deoxidized copper according to the level wound coil of the present invention is the same as the phosphorous deoxidized copper of the seamless tube of the present invention. In the level wound coil of the present invention, the outer diameter D and the wall thickness t of the seamless pipe wound around the level wound coil are the same as the outer diameter D and the wall thickness t of the seamless pipe of the present invention.

In the level wound coil of the present invention, the ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the level wound coil is 0.040 or less, preferably 0.020. To 0.040, particularly preferably 0.030 to 0.038.

In the level wound coil of the present invention, the tensile strength (σ _B ) of the seamless pipe wound around the level wound coil is 245 MPa or more, preferably 245 to 265 MPa. Since the tensile strength (σ _B ) of the seamless pipe wound around the level-wound coil is in the above range, the seamless pipe after being unwound from the level-wound coil, that is, a cross-fin tube heat exchanger The tensile strength (σ _B ) of the seamless pipe subjected to the hairpin bending process for the production of 245 MPa can be 245 MPa or more, preferably 245 to 265 MPa.

In the level wound coil of the present invention, the 0.2% yield strength (σ _0.2 ) of the seamless pipe wound around the level wound coil is 130 MPa or less, preferably 80 to 110 MPa. Since the 0.2% proof stress (σ _0.2 ) of the seamless pipe wound around the level-wound coil is in the above range, the seamless pipe after being unwound from the level-wound coil, that is, the cross fin tube The 0.2% proof stress (σ _0.2 ) of a seamless pipe subjected to hairpin bending for the production of a mold heat exchanger can be 140 MPa or less, preferably 80 to 120 MPa.

In the level wound coil of the present invention, the elongation (δ) of the seamless pipe wound around the level wound coil is 40% or more, preferably 40 to 55%. Since the elongation (δ) of the seamless pipe wound around the level-wound coil is in the above range, the seamless pipe after being unwound from the level-wound coil, that is, the production of the cross fin tube type heat exchanger Therefore, the elongation (δ) of the seamless pipe subjected to the hairpin bending process can be 40% or more, preferably 40 to 55%.

In the level wound coil of the present invention, the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ) and elongation (δ) of the seamless pipe wound around the level wound coil are within the above ranges. By being set, the tensile strength (σ _B ) of the seamless pipe after being unwound from the level wound coil, that is, the seamless pipe subjected to hairpin processing, is 245 MPa or more, preferably 245 to 265 MPa. The 0.2% proof stress (σ _0.2 ) is 140 MPa or less, preferably 80 to 120 MPa, and the elongation (δ) is 40% or more, preferably 40 to 55%.

In the level wound coil, for example, the seamless pipe obtained by performing the final annealing treatment according to the first seamless pipe manufacturing method of the present invention or the second seamless pipe manufacturing method of the present invention has a cylindrical shape. It is wound up into an aligned multilayer winding. Here, when the seamless pipe is wound into a cylindrical shape, since the work hardening by bending is added to the seamless pipe, the 0.2% proof stress of the seamless pipe wound around the level wound coil is Compared to the 0.2% proof stress of the seamless pipe before being wound around the level wound coil. As described above, the 0.2% proof stress of the seamless pipe also increases when it is unwound from the level wound coil. Therefore, the 0.2% proof stress of the seamless pipe before being wound around the level wound coil, for example, the manufacturing method of the seamless pipe according to the first aspect of the present invention or the seamless pipe according to the second aspect of the present invention. The 0.2% proof stress of the seamless pipe obtained by performing the final annealing treatment according to the manufacturing method takes into account the increase when wound around the level wound coil and the increase when unrolled from the level wound coil. Must be designed to the specified range.

For this reason, the seamless pipe used for the production of the level wound coil is made of phosphorous-deoxidized copper, and the ratio of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe. (T / D) is 0.040 or less, preferably 0.020 to 0.040, particularly preferably 0.030 to 0.038, and the tensile strength (σ _B ) of the seamless pipe is 245 MPa or more, preferably Is 245 to 265 MPa, 0.2% proof stress (σ _0.2 ) is 120 MPa or less, preferably 80 to 100 MPa, and elongation (δ) is 40% or more, preferably 40 to 55%. A seamless tube for producing a wound coil is preferred. Then, such a levelwound coil production seamless tube is wound in a multilayered arrangement in a cylindrical shape to produce a levelwound coil, and then the seamless tube is unwound from the produced levelwound coil to obtain a cross fin. As a seamless tube used for hairpin bending when manufacturing a tube heat exchanger, the material is phosphorous deoxidized copper, and the ratio of thickness (mm) to outer diameter (mm) (t / D) Is 0.040 or less, preferably 0.020 to 0.040, particularly preferably 0.030 to 0.038, and the tensile strength (σ _B ) is 245 MPa or more, preferably 245 to 265 MPa. Obtaining a seamless tube having a 2% proof stress (σ _0.2 ) of 140 MPa or less, preferably 80 to 120 MPa and an elongation (δ) of 40% or more, preferably 40 to 55% Can do.

In this method, the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe for producing the level wound coil are set in the above ranges. In the method of manufacturing a seamless pipe of the form of the present invention or the method of manufacturing the seamless pipe of the second aspect of the present invention, the total working degree of the cold working step, the holding temperature or holding of the intermediate annealing process (A) or the final annealing process By appropriately selecting the time, the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe for producing the level wound coil can be within the above ranges.

In addition, although the level-wound coil was described in detail above, the coil of the present invention is not limited to this. For example, it may be a coil obtained by stacking pancakes in multiple layers by sequentially repeating bunch winding or adjusting the winding diameter directly on the tray without performing aligned winding on bobbins.

The cross fin tube type heat exchanger of the present invention is obtained by bending a seamless tube unwound from the seamless tube of the present invention, the coil of the present invention or the level wound coil of the present invention by hairpin bending into an aluminum fin. It is a cross fin tube type heat exchanger obtained by assembling.

Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

Below, the Example in case a seamless pipe is an internal grooved pipe is shown.
(Examples 1 and 2)
(1) An ingot of phosphorous deoxidized copper (JIS H3300 C1220) having the following chemical components was melted and cast to produce a billet for hot extrusion.
-Phosphorus-deoxidized copper had a P content of 0.025% by mass, a Cu content of 99.97% by mass, and the others were inevitable impurities.
(2) The billet was heated and subjected to hot extrusion at 850 ° C. to obtain an extruded tube. Next, the extruded extruded tube was extruded into water and quenched.
-The inner diameter was about 75 mm perforated before extrusion.
-The outer diameter of the extruded element tube was 102 mm, and the inner diameter was 75 mm.
(3) The extruded blank was cold-rolled with a Birger mill to obtain a rolled blank.
-The rolling tube had an outer diameter of 46 mm and an inner diameter of 39.8 mm.
-The degree of work in cold rolling (cross-sectional reduction rate) was 88.9%.
Cross-sectional reduction rate (%) = ((cross-sectional area before processing−cross-sectional area after processing) / cross-sectional area before processing) × 100
(4) The above-mentioned rolled blank was cold drawn a plurality of times to obtain a drawn blank.
-The outer diameter of the drawing element tube was 38 mm, and the inner diameter was 33 mm.
-The degree of work in the entire cold drawing was 98.2% in terms of the cross-section reduction rate.
-The total working degree of cold rolling and cold drawing, that is, the total working degree of cold working was 99.8% in terms of the cross-section reduction rate.
(5) The above-mentioned drawn element pipe was subjected to intermediate annealing to obtain an original pipe for use in the rolling process.
・ Intermediate annealing conditions are as shown in Table 1.
Table 1 shows the 0.2% proof stress (σ _0.2 ) and average grain size of the original pipe.
(6) The above-mentioned original pipe was processed by ball rolling to obtain an internally grooved pipe A having the following dimensions.
<Dimensions of inner grooved tube A>
・ Outer diameter: 7.0mm
・ Wall thickness (in FIG. 2, symbol t): 0.26 mm
-Fin height (symbol h in FIG. 2): 0.22 mm
-Fin apex angle (symbol α in FIG. 2): 13 °
・ Number of grooves: 44 ・ Lead angle: 28 °
-Ratio of thickness (mm) to outer diameter (mm) of inner grooved tube (t / D): 0.037
(7) The inner grooved tube was wound up into a coil shape and subjected to a final annealing treatment under the following conditions to obtain a seamless tube (for producing a level wound coil (LWC)).
-Annealing method: performed in a roller hearth continuous annealing furnace.
-Conditions: The holding temperature is as shown in Table 1, the rate of temperature increase is 5.0 ° C / min from 25 ° C to the holding temperature, and the cooling rate is 2.2 ° C / min from the holding temperature to 25 ° C. It was.
Table 1 shows the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe (for LWC production) after the final annealing treatment.
(8) The above seamless pipe (for LWC production) was wound around a cylindrical aligned multilayer winding to produce an LWC of the type that was unwound from the inner surface side.
Table 1 shows the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe wound around the LWC.
(9) The seamless tube was unwound from the inner surface side of the LWC to obtain a seamless tube (for heat transfer tubes of a cross fin tube type heat exchanger).
Table 1 shows the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of seamless tubes (for heat transfer tubes of cross fin tube heat exchangers).
(10) Using the above seamless tube (for heat transfer tube of cross fin tube type heat exchanger), a hairpin bending test was performed under the following conditions to evaluate workability. The results are shown in Table 1.
・ Hairpin bending test method: The position where the shoulder of the one-neck swing ball mandrel and the bending start position of the bending mold are aligned on a straight line is 0 point, and the mandrel position is 2.0 in the direction away from the bending R part. The hairpin processability was evaluated while shifting within a range of ˜5.5 mm.
-Hairpin bending test conditions: Ball mandrel outer diameter is 5.90 mm, bending pitch is 22 mm
-About 20 seamless pipes of each Example and Comparative Example, 20 tests were performed.
<Evaluation>
(I) Wrinkle generation The number of seamless tubes in which wrinkles are generated in the inner part of the hairpin bend was counted, and the wrinkle generation rate was determined by the following formula. The case where the wrinkle occurrence rate was 0% was regarded as acceptable.
Wrinkle generation rate (%) = (number of tubes with wrinkles / number of tubes tested) × 100
(II) Flatness The flatness of the bent part after hairpin bending was calculated as follows.
Flatness ratio (%) = ((maximum outer diameter−minimum outer diameter) / nominal outer diameter) × 100
In addition, a measurement position is a 45 degree, 90 degree, and 135 degree position of a hairpin bending part, and a nominal outer diameter is 7.0 mm in this example. In addition, as shown in FIG. 1, 45 degrees, 90 degrees, and 135 degrees of a hairpin bending part are the position (code | symbol a) which bent the seamless pipe 45 degrees, the position (code | symbol b) which bent 90 degrees, and 135 degrees. It is the bent position (symbol c).
The flatness of each seamless pipe tested was determined, and the average value of the flatness was 15% or less.
<Tensile strength (σ _B ), 0.2% yield strength (σ _0.2 ), elongation (δ)>
The tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe were measured according to JIS Z 2241.
<Average grain size>
The average crystal grain size of the seamless tube was measured by using a comparative method defined in JIS H0501, and an average value of 10 arbitrary points was defined as the average crystal grain size.

In both Examples 1 and 2, the hairpin bending wrinkles and the flatness ratio passed, and a normal hairpin bending process could be performed.

(Comparative Examples 1 and 2 and Reference Example 1)
(1) An ingot of phosphorous deoxidized copper (JIS H3300 C1220) having the following chemical components was melted and cast to produce a billet for hot extrusion.
-Phosphorus-deoxidized copper had a P content of 0.025% by mass, a Cu content of 99.97% by mass, and the others were inevitable impurities.
(2) The billet was heated and subjected to hot extrusion at 850 ° C. to obtain an extruded tube. Next, the extruded extruded tube was extruded into water and quenched.
-The inner diameter was about 75 mm perforated before extrusion.
-The outer diameter of the extruded element tube was 102 mm, and the inner diameter was 75 mm.
(3) The extruded blank was cold-rolled with a Birger mill to obtain a rolled blank.
-The rolling tube had an outer diameter of 46 mm and an inner diameter of 39.8 mm.
-The degree of work in cold rolling (cross-sectional reduction rate) was 88.9%.
Cross-sectional reduction rate (%) = ((cross-sectional area before processing−cross-sectional area after processing) / cross-sectional area before processing) × 100
(4) The above-mentioned rolled blank was cold drawn a plurality of times to obtain a drawn blank.
-The outer diameter of the drawing element tube was 38 mm, and the inner diameter was 33 mm.
(5) The above-mentioned drawn element pipe was subjected to intermediate annealing to obtain an original pipe for use in the rolling process.
・ Intermediate annealing conditions are as shown in Table 2.
-The one that has been subjected to the intermediate annealing treatment (A) at 440 ° C is used as the original pipe.
Table 2 shows the 0.2% proof stress (σ _0.2 ) and average grain size of the original tube.
(6) The above-mentioned original pipe was subjected to ball rolling to obtain an internally grooved pipe A or B having the following dimensions.
<Dimensions of inner grooved tube A>
・ Outer diameter: 7.0mm
・ Wall thickness (in FIG. 2, symbol t): 0.26 mm
-Fin height (symbol h in FIG. 2): 0.22 mm
-Fin apex angle (symbol α in FIG. 2): 13 °
・ Number of grooves: 44 ・ Lead angle: 28 °
-Ratio of thickness (mm) to outer diameter (mm) of inner grooved tube (t / D): 0.037
In addition, in the manufacture of the inner surface grooved tube A, the workability of the entire cold drawing is 98.2% in terms of the cross-sectional reduction rate, that is, the total workability of cold rolling and cold drawing, that is, cold The total processing degree of processing was 99.8% in terms of the cross-section reduction rate.
<Dimensions of inner grooved tube B>
・ Outer diameter: 7.0mm
・ Wall thickness (in FIG. 2, symbol t): 0.29 mm
-Fin height (symbol h in FIG. 2): 0.22 mm
-Fin apex angle (symbol α in FIG. 2): 13 °
・ Number of grooves: 44 ・ Lead angle: 28 °
-Ratio (t / D) of wall thickness (mm) to outer diameter (mm) of inner grooved tube: 0.041
In addition, in the manufacture of the inner surface grooved tube B, the workability in the entire cold drawing is 97.2% in terms of the cross-sectional reduction rate, that is, the total workability of cold rolling and cold drawing, ie, cold The total degree of processing was 99.7% in terms of the cross-section reduction rate.
(7) The inner grooved tube was wound up into a coil shape and subjected to a final annealing treatment under the following conditions to obtain a seamless tube (for producing a level wound coil (LWC)).
-Annealing method: performed in a roller hearth continuous annealing furnace.
-Conditions: The holding temperature is as shown in Table 1, the rate of temperature increase is 5.0 ° C / min from 25 ° C to the holding temperature, and the cooling rate is 2.2 ° C / min from the holding temperature to 25 ° C. It was.
Table 2 shows the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe (for LWC production) after the final annealing treatment.
(8) The above seamless pipe (for LWC production) was wound around a cylindrical aligned multilayer winding to produce an LWC of the type that was unwound from the inner surface side.
Table 2 shows the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of the seamless pipe wound around the LWC.
(9) The seamless tube was unwound from the inner surface side of the LWC to obtain a seamless tube (for heat transfer tubes of a cross fin tube type heat exchanger).
Table 2 shows the tensile strength (σ _B ), 0.2% proof stress (σ _0.2 ), and elongation (δ) of seamless tubes (for heat transfer tubes of cross fin tube heat exchangers).
(10) Using the above seamless tube (for heat transfer tube of cross fin tube type heat exchanger), a hairpin bending test was performed under the same conditions as in Example, and the workability was evaluated. The results are shown in Table 2.

In Comparative Examples 1 and 2 in which the 0.2% proof stress of the seamless tube of the hairpin bending test exceeds 140 MPa, the paired pin bending wrinkles and the flatness ratio were unacceptable, and normal hairpin bending processing could not be performed. .

Moreover, t / D exceeds 0.040 although t / D exceeded 0.040, although the hairpin bending wrinkle and the flatness ratio were passing and it was able to perform normal hairpin bending process, t / D exceeded 0.040. Since the mass per unit length of the seamless tube becomes too high, it cannot be thinned.

Since the seamless pipe of the present invention is a seamless pipe made of phosphorous deoxidized copper which has high strength and can bend hairpin normally, the heat transfer pipe made of phosphorous deoxidized copper can be thinned. Therefore, the cross fin tube type heat exchanger manufactured by assembling the seamless tube of the present invention can easily recycle the heat transfer tube after disposal.

1 Pipe axis P Bending pitch t Thickness (bottom thickness)
h Fin height s Deepest position of inner groove α Fin apex angle

Claims

A seamless tube for a heat transfer tube of a cross fin tube type heat exchanger,
The material of the seamless pipe is phosphorus deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe is 0.040 or less,
The seamless pipe has a tensile strength (σ B ) of 245 MPa or more,
0.2% proof stress (σ 0.2 ) is 140 MPa or less,
Elongation (δ) is 40% or more,
Seamless tube characterized by
A casting process for casting phosphorous deoxidized copper, a hot extrusion process, a cold working process for performing cold working with a total working degree of 99.5% or more in cross-sectional reduction rate, an intermediate annealing process (A), The seamless pipe according to claim 1, wherein the seamless pipe is obtained by sequentially performing a rolling process step and a final annealing treatment in which annealing is performed at a holding temperature of 360 to 600 ° C.
The seamless pipe according to any one of claims 1 and 2, wherein the inner pipe is a grooved pipe provided with a plurality of spiral grooves on the inner face.
A coil made by winding a seamless tube,
The material of the seamless pipe wound around the coil is phosphorus deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the coil is 0.040 or less,
The tensile strength (σ B ) of the seamless pipe wound around the coil is 245 MPa or more,
0.2% proof stress (σ 0.2 ) is 130 MPa or less,
Elongation (δ) is 40% or more,
Coil characterized by
The coil is a level-wound coil made by aligning multiple layers in a cylindrical shape,
The material of the seamless pipe wound around the level wound coil is phosphorous deoxidized copper,
The ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) of the seamless pipe wound around the level wound coil is 0.040 or less,
The tensile strength (σ B ) of the seamless pipe wound around the level wound coil is 245 MPa or more,
0.2% proof stress (σ 0.2 ) is 130 MPa or less,
Elongation (δ) is 40% or more,
A level-wound coil characterized by
6. The level-wound coil according to claim 5, wherein the level-wound coil is a level-wound coil in which the seamless axis is unwound from the cylindrical inner surface side of the coil with the coil axis arranged vertically. .
The material is phosphorous deoxidized copper, the ratio (t / D) of the wall thickness (mm) to the outer diameter (mm) is 0.040 or less, the tensile strength (σ B ) is 245 MPa or more, 0 A level-wound coil is manufactured by winding a level-wound coil seamless pipe having a 2% proof stress (σ 0.2 ) of 120 MPa or less and an elongation (δ) of 40% or more in a cylindrical arrangement. A method for producing a level-wound coil.
A cross-fin obtained by bending a seamless pipe unwound from the coil according to any one of claims 1 to 3 or a seamless pipe unwound from the coil according to any one of claims 4 to 6 into a hairpin and assembling it to an aluminum fin. Tube heat exchanger.
A seamless tube according to any one of claims 1 to 3 or a seamless tube unwound from a coil according to any one of claims 4 to 6 is bent with a hairpin and assembled to an aluminum fin to produce a cross fin tube type heat A method of manufacturing a cross fin tube heat exchanger, comprising obtaining an exchanger.