JP2004218083A - Aluminum pipe and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum pipe being manufactured simply and inexpensively and having sufficient pitting corrosion resistance and to provide its manufacturing method. <P>SOLUTION: The aluminum pipe is formed of an alloy containing 0.90-1.50 mass% Mn and the balance Al and inevitable impurities and its electroconductivity is 30-43 LACS. The aluminum pipe is formed by heating the pipe material formed of the alloy containing 0.90-1.50 mass% Mn and the balance Al and inevitable impurities at 550-600°C for 10-600 min in the atmosphere or in an inert gas atmosphere then cooling. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum pipe and a method for manufacturing the same, and more particularly, for example, a condenser and an evaporator of a car air conditioner using a Freon-based refrigerant, a gas cooler and an evaporator of a car air conditioner using a CO ₂ refrigerant, an oil cooler for a car, and a radiator for a car The inlet and outlet pipes of a heat exchanger used as a compressor, a compressor for a car air conditioner comprising a refrigeration cycle that uses a chlorofluorocarbon refrigerant and has a compressor, a condenser and an evaporator, piping between the condenser and an evaporator, and compression. machine, gas cooler, intermediate heat exchanger, the expansion valve and consists of a refrigeration cycle using the provided and CO ₂ refrigerant evaporator car air conditioner compressors, gas cooler, intermediate heat exchanger, the aluminum used as a piping between the expansion valve and the evaporator Tube and its It relates to a method for manufacturing.

  In this specification and in the claims, the term “aluminum” shall include aluminum alloys in addition to pure aluminum. Naturally, the metal represented by the element symbol does not include the alloy.

  For example, as a condenser for a car air conditioner comprising a refrigeration cycle using a chlorofluorocarbon-based refrigerant, a pair of aluminum headers arranged in parallel at an interval from each other, and a parallel aluminum header having both ends connected to both headers, respectively. Flat heat exchange pipes, aluminum corrugated fins that are arranged in the ventilation gap between adjacent heat exchange pipes and brazed to both heat exchange pipes, and aluminum inlet pipes connected to one header And an aluminum outlet tube connected to the other header is known.

  Conventionally, as the inlet pipe and the outlet pipe of the above-mentioned condenser, JIS A1100, JIS A3003, Mn containing 1.0 to 1.5 wt% and Mg not less than 0.2 wt% and less than 0.6 wt% However, it is formed of an alloy including the remaining Al and inevitable impurities (see Patent Document 1).

Further, as an aluminum pipe used as a pipe between a compressor, a condenser and an evaporator in a car air conditioner, conventionally, Mn 0.3 to 1.5% by mass, Cu 0.20% by mass or less, Ti 0.06 to 0.30% by mass, Si-based compound, Fe-based compound formed of an alloy containing 0.01 to 0.20% by mass of Fe and 0.01 to 0.20% by mass of Si, the balance being Al and unavoidable impurities, and present in a matrix of this alloy Also, it is known that among the Mn-based compounds, compounds having a particle size of 0.5 μm or more are 2 × 10 ⁴ or less per 1 mm ² (see Patent Document 2).

By the way, the heat exchange tubes, inlet and outlet tubes of condensers and evaporators in car air conditioners as described above, and aluminum pipes in car air conditioners have conventionally been subjected to chromate treatment on the surface for the purpose of improving corrosion resistance. However, the processing was troublesome. Further, Cr ⁶⁺ is a harmful substance, and waste liquid treatment was troublesome. Therefore, there has been a problem that the operation of manufacturing the heat exchange tube, the inlet tube, the outlet tube, and the piping of the condenser and the evaporator is troublesome. Moreover, in Europe, the use of Cr ⁶⁺ will be banned in the near future.

Therefore, for the condenser and the heat exchange tube of the evaporator, various types of pitting corrosion-resistant treatments and pitting-corrosion-resistant treatments have been studied in place of the chromate treatment using harmful Cr ⁶⁺ .

However, at present, there has not been found any of the above inlet and outlet pipes and pipes that can be manufactured easily and inexpensively and has sufficient pitting corrosion resistance. Of course, even in the inlet pipe and the outlet pipe described in Patent Literature 1 and the pipe described in Patent Literature 2, pitting corrosion resistance cannot be expected unless chromate treatment is performed.
Japanese Patent Publication No. 3-22459 JP 2002-180171 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an aluminum pipe which solves the above problems, can be manufactured simply and inexpensively, and has sufficient pitting resistance, and a method for manufacturing the same.

  The present invention has the following aspects to achieve the above object.

  1) An aluminum tube containing Mn 0.90 to 1.50% by mass, made of an alloy consisting of the balance of Al and unavoidable impurities, and having a conductivity of 30 to 43% IACS.

  In the aluminum tube of the above 1), Mn has an effect of improving pitting corrosion resistance and strength, but if the content is less than 0.90% by mass, the above effect cannot be obtained, and 1.50% by mass. If the ratio exceeds, the effect of improving strength is saturated, but the deformation resistance during hot working increases, and the workability at the time of forming an aluminum tube, for example, the extrudability, decreases. Therefore, the Mn content of the alloy forming the aluminum tube should be 0.90 to 1.50% by mass, but is preferably 1.0 to 1.2% by mass.

  Further, in the aluminum tube of the above 1), if the conductivity is less than 30% IACS, the amount of Mn is insufficient and the strength is reduced, and if it exceeds 43% IACS, the Mn and unavoidable impurities are introduced into the matrix. Insufficient solid solution lowers the corrosion resistance. Thus, the conductivity of the alloy forming the aluminum tube should be 30-43% IACS, but preferably 33-37% IACS.

  2) The aluminum tube as described in 1) above, wherein Cu is contained as an unavoidable impurity, and the content of Cu is 0.05% by mass or less.

  In the aluminum tube of the above 2), Cu as an unavoidable impurity may reduce the pitting corrosion resistance of the aluminum tube even if mixed in a small amount. Therefore, the Cu content is preferably set to 0.05% by mass or less.

  3) The aluminum tube according to 1) or 2), wherein Fe is contained as an unavoidable impurity, and the content of Fe is 0.25% by mass or less.

  In the aluminum tube of the above 3), Fe as an unavoidable impurity is not as strong as Cu, but may reduce the pitting corrosion resistance of the aluminum tube. Therefore, the Fe content is preferably set to 0.25% by mass or less.

  4) The aluminum tube according to any one of 1) to 3) above, wherein Si is contained as an unavoidable impurity, and the content of Si is 0.25% by mass or less.

  In the aluminum tube of 4), Si as an unavoidable impurity may reduce the pitting corrosion resistance of the aluminum tube, similarly to Fe. Therefore, the Si content is preferably set to 0.25% by mass or less.

  5) A tube material containing 0.90 to 1.50% by mass of Mn and formed of an alloy consisting of the balance of Al and inevitable impurities is heated to 550 to 600 ° C. in an air atmosphere or an inert gas atmosphere to form a tube material. A method for producing an aluminum tube, comprising holding for 600 minutes and then cooling.

  In the method for producing an aluminum pipe according to the above 5), when the pipe material is heated to a predetermined temperature and held for a predetermined time, Mn and unavoidable impurities in an alloy forming the pipe material are dissolved in a matrix to cause corrosion. Crystals and precipitates in the nucleus material are reduced, and the corrosion resistance is improved. As a result, the electrical conductivity is reduced, and the pitting corrosion resistance of the manufactured aluminum tube is improved. Here, the heating temperature is set to 550 to 600 ° C. If the heating temperature is lower than 550 ° C., the solid solution of Mn and unavoidable impurities in the matrix is insufficient, and even if the heating temperature exceeds 600 ° C., the efficiency is low. This is because the effect of solid solution of Mn and unavoidable impurities in the matrix is not improved. If the heating and holding time is set to 10 to 600 minutes, if it is less than 10 minutes, the solid solution of Mn and unavoidable impurities in the matrix is insufficient, and even if it exceeds 600 minutes, the efficiency is low economically. This is because the effect of solid solution of Mn and unavoidable impurities in the matrix is not improved.

  6) The method for producing an aluminum tube according to 5) above, wherein the alloy forming the tube material contains Cu as an inevitable impurity, and the content of Cu is 0.05% by mass or less.

  7) The method for producing an aluminum tube according to the above 5) or 6), wherein the alloy forming the tube material contains Fe as an unavoidable impurity, and the content of Fe is 0.25% by mass or less.

  8) The aluminum tube according to any one of the above 5) to 7), wherein the alloy forming the tube material contains Si as an unavoidable impurity, and the content of Si is 0.25% by mass or less. Production method.

  9) The method for producing an aluminum tube according to any one of the above items 5) to 8), wherein the heating rate during heating is 20 to 130 ° C / min.

  In the method for manufacturing an aluminum tube according to the above item 9), the heating rate during heating is set to 20 to 130 ° C./min. If the heating rate is less than 20 ° C./min, the efficiency is low economically. This is because there is a possibility that the temperature rise of another product such as another aluminum tube heated at the same time as exceeding 130 ° C./min may be varied.

  10) The method for producing an aluminum tube according to any one of the above 5) to 9), wherein a cooling rate after heating is 47 ° C / min or more.

  In the method for manufacturing an aluminum tube according to the above item 10), the cooling rate after heating is set to 47 ° C./min or more because if the cooling rate is less than 47 ° C./min, Mn and unavoidable impurities dissolved in the matrix are dissolved. This is because reprecipitation may occur and the corrosion resistance may be reduced.

  11) A heat exchanger for a vehicle, wherein the aluminum tube according to any one of the above 1) to 4) is used as an inlet tube and an outlet tube.

  12) A vehicle having a compressor, a condenser, an evaporator, and a car air conditioner comprising a refrigeration cycle using a chlorofluorocarbon-based refrigerant, wherein the condenser comprises the heat exchanger described in 11) above.

  13) It has a compressor, a condenser and an evaporator and uses a chlorofluorocarbon refrigerant, and the aluminum pipe according to any one of the above 1) to 4) is used as piping between the compressor, the condenser and the evaporator. Refrigeration cycle.

  14) A vehicle equipped with the refrigeration cycle described in 13) above as a car air conditioner.

According to the aluminum tube of 1), since the electrical conductivity is 30 to 43% IACS, the occurrence of pitting corrosion can be prevented without performing a chromate treatment. In addition, since the alloy contains Mn 0.90 to 1.50 mass% and is made of an alloy consisting of the balance of Al and inevitable impurities, the strength is improved and excellent workability is secured. In addition, since it can be manufactured by simply heating it to a predetermined temperature in an air atmosphere or an inert gas atmosphere, holding it for a predetermined time, and then cooling it, it can be manufactured simply and inexpensively.
According to the above aluminum tubes 2) to 4), the pitting resistance is further improved.

  According to the method for manufacturing an aluminum tube of the above 5), the above-described aluminum tube can be manufactured relatively easily and at low cost.

  According to the above-described methods 6) to 8) for manufacturing aluminum tubes, the aluminum tubes 2) to 4) can be manufactured relatively easily and inexpensively.

  According to the aluminum pipe manufacturing methods of 9) and 10) above, the economic efficiency is excellent and the pitting corrosion resistance of the manufactured aluminum pipe can be ensured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a condenser for a car air conditioner using an aluminum pipe according to the present invention as an inlet pipe and an outlet pipe.

  In FIG. 1, a condenser (1) used in a car air conditioner using a chlorofluorocarbon-based refrigerant includes a pair of aluminum headers (2) and (3) arranged in parallel at a distance from each other, and both ends are both headers. (2) A flat refrigerant flow pipe (4) (heat exchange pipe) made of parallel extruded aluminum members connected to (3) and a ventilation gap between adjacent refrigerant flow pipes (4) Also, an aluminum brazing sheet corrugated fin (5) brazed to both refrigerant flow pipes (4), and an aluminum extruded profile inlet pipe (6) welded to the upper end of the peripheral wall of the first header (2). An outlet pipe (7) made of an extruded aluminum member welded to the lower end of the peripheral wall of the second header (3), and a first partition plate (7) provided inside a position above the middle of the first header (2). 8), and a second partition plate (9) provided inside a position lower than the middle of the second header (3). Note that, as the refrigerant flow pipe (4), a pipe made of an electric resistance welded pipe may be used.

  The number of refrigerant flow pipes (4) between the inlet pipe (6) and the first partition (8), and the number of refrigerant flow pipes (4) between the first partition (8) and the second partition (9) The number of the refrigerant flow pipes (4) between the second partition plate (9) and the outlet pipe (7) is sequentially reduced from the top to form a passage group, and the number of the refrigerant flow pipes has flowed from the inlet pipe (6). By the time the gas-phase refrigerant flows out of the outlet pipe (7) as a liquid phase, the refrigerant flows in the condenser (1) in a meandering manner for each passage group.

The inlet pipe (6) and the outlet pipe (7) each contain Mn 0.90 to 1.50 mass%, are formed of an alloy consisting of the balance Al and unavoidable impurities, and have a conductivity of 30 to 43% IACS. ing.
When Cu is contained as an inevitable impurity in the alloy forming the inlet pipe (6) and the outlet pipe (7), the content of Cu as the inevitable impurity is preferably 0.05% by mass or less. When the alloy forming the inlet pipe (6) and the outlet pipe (7) contains Fe as an inevitable impurity, the content of Fe as the inevitable impurity is preferably 0.25% by mass or less. Furthermore, when the alloy forming the inlet pipe (6) and the outlet pipe (7) contains Si as an inevitable impurity, the content of Si as the inevitable impurity is preferably 0.25% by mass or less.

  The inlet pipe (6) and the outlet pipe (7) are manufactured, for example, as follows.

  That is, after the inlet tube material and the outlet tube material are extruded by using the alloy as described above, these tube materials are heated to 550 to 600 ° C. in an air atmosphere or an inert gas atmosphere to be heated to 10 to 600 ° C. Hold for a minute and then cool. Here, the heating rate during heating is 20 to 130 ° C./min, and the cooling rate after heating is 47 ° C./min or more. Thus, the inlet pipe (6) and the outlet pipe (7) are manufactured.

  When the tube material is heated to a predetermined temperature and held for a predetermined time, Mn and unavoidable impurities in the alloy forming the tube material dissolve in the matrix, thereby causing crystallization and precipitation in the material that becomes a nucleus of corrosion. The corrosion resistance is improved by reducing the amount of material, and as a result, the electrical conductivity is reduced, and the pitting corrosion resistance of the manufactured aluminum tube is improved.

  In the above-described embodiment, the aluminum pipe according to the present invention is used as an inlet pipe and an outlet pipe of a condenser of a car air conditioner including a refrigeration cycle using a Freon-based refrigerant. Sometimes used as an outlet pipe. Further, the aluminum pipe according to the present invention may be used as an inlet pipe and an outlet pipe of a heat exchanger used as an automobile oil cooler, an automobile radiator, or the like.

In addition, the aluminum pipe according to the present invention includes a compressor, a pipe between the condenser and the evaporator, a compressor, a gas cooler, an intermediate heat exchanger, and a compressor of a car air conditioner including a compressor, a condenser and an evaporator and comprising a refrigeration cycle using a chlorofluorocarbon-based refrigerant. It may be used as a pipe between a compressor, a gas cooler, an intermediate heat exchanger, an expansion valve, and an evaporator of a car air conditioner comprising a refrigeration cycle using a CO ₂ refrigerant and a compressor, an expansion valve, and an evaporator.

Further, the aluminum pipe according to the present invention is used as an inlet pipe and an outlet pipe of a gas cooler and an evaporator of a car air conditioner including a compressor, a gas cooler, an intermediate heat exchanger, an expansion valve, and an evaporator and comprising a refrigeration cycle using a CO ₂ refrigerant. Sometimes it is done.

  Hereinafter, specific examples of the present invention will be described together with comparative examples.

Examples 1-4
Using four kinds of alloys having the compositions shown in Table 1, tube materials having an outer diameter of 9.53 mm and a wall thickness of 1.0 mm were extruded, respectively.

  Next, these tube materials were placed in a preheating furnace in which the furnace temperature was set at 500 ° C., and maintained for 10 minutes, and then placed in a main heating furnace in which the furnace temperature was set at 601 ° C. When the actual temperature of the material was maintained at 600 ° C. for 3 minutes, the tube material was cooled to 570 ° C. with nitrogen gas, and then taken out of the heating furnace. The heating rate during heating is 30 ° C./min, and the cooling rate is 60 ° C./min. The heating pattern is shown in FIG.

  The conductivity of the tube thus manufactured was measured. The results are also shown in Table 1.

Each tube was subjected to a SWAAT 960 hr test to check the corrosion state. As a result, the maximum corrosion depth in each tube was as shown in Table 1. Further, the state of occurrence of corrosion in each pipe, that is, the depth of corrosion and the number of corrosion were as shown in Table 2.

Comparative Examples 1-4
Using four types of alloys having the compositions shown in Table 1, each tube material having an outer diameter of 9.53 mm and a wall thickness of 1.0 mm was extruded, and each tube material was subjected to SWAAT 960 hr without heat treatment. As a result of conducting a test and examining the state of corrosion, pitting corrosion penetrating the peripheral wall occurred.

1 is a perspective view showing a condenser having an aluminum pipe according to the present invention as an inlet pipe and an outlet pipe and used for a car air conditioner using a chlorofluorocarbon-based refrigerant. It is a figure which shows the heating pattern of Examples 1-4.

Explanation of reference numerals

(6): Inlet pipe
(7): Outlet pipe

Claims (14)

An aluminum tube containing Mn of 0.90 to 1.50% by mass, made of an alloy composed of the balance of Al and unavoidable impurities, and having a conductivity of 30 to 43% IACS. The aluminum tube according to claim 1, wherein Cu is contained as an unavoidable impurity, and the content of Cu is 0.05% by mass or less. 3. The aluminum tube according to claim 1, wherein Fe is contained as an unavoidable impurity, and the content of Fe is 0.25% by mass or less. The aluminum tube according to any one of claims 1 to 3, wherein Si is contained as an unavoidable impurity, and the content of Si is 0.25% by mass or less. A tube material containing 0.90 to 1.50% by mass of Mn and made of an alloy consisting of the balance of Al and inevitable impurities is heated to 550 to 600 ° C. in an air atmosphere or an inert gas atmosphere for 10 to 600 minutes. A method for producing an aluminum tube, comprising holding and then cooling. The method for manufacturing an aluminum tube according to claim 5, wherein the alloy forming the tube material contains Cu as an unavoidable impurity, and the content of Cu is 0.05% by mass or less. 7. The method for producing an aluminum tube according to claim 5, wherein the alloy forming the tube material contains Fe as an unavoidable impurity, and the content of Fe is 0.25% by mass or less. The method for producing an aluminum tube according to any one of claims 5 to 7, wherein the alloy forming the tube material contains Si as an inevitable impurity, and the content of Si is 0.25% by mass or less. The method for producing an aluminum tube according to any one of claims 5 to 8, wherein a heating rate during heating is 20 to 130 ° C / min. The method for producing an aluminum tube according to any one of claims 5 to 9, wherein a cooling rate after the heating is 47 ° C / min or more. An automotive heat exchanger, wherein the aluminum pipe according to any one of claims 1 to 4 is used as an inlet pipe and an outlet pipe. A vehicle comprising a compressor, a condenser and an evaporator, a car air conditioner comprising a refrigeration cycle using a chlorofluorocarbon-based refrigerant, and a condenser comprising the heat exchanger according to claim 11. Refrigeration having a compressor, a condenser and an evaporator and using a chlorofluorocarbon refrigerant, and wherein the aluminum pipe according to any one of claims 1 to 4 is used as piping between the compressor, the condenser and the evaporator. cycle. A vehicle in which the refrigeration cycle according to claim 13 is mounted as a car air conditioner.

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