JP3439897B2 - Copper tube coil manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a copper tube coil used in heat exchangers for air conditioners and refrigerators,
In particular, the present invention relates to a method for manufacturing a copper tube coil with a small amount of residual oil in the tube.

[0002]

2. Description of the Related Art A copper tube coil made of copper used in heat exchangers of air conditioners and refrigerators is manufactured by extruding a metal ingot and then drawing it into a copper tube, which is wound into a coil. It was obtained. Usually, in order to soften the copper tube coil, the coil is heated and annealed in a reducing atmosphere or an inert atmosphere. In such a manufacturing process, a hydrocarbon-based inner surface lubricating oil such as polybutene is used when drawing a copper tube coil. If this inner surface lubricating oil remains in the copper tube coil, it adversely affects the subsequent process. Therefore, by utilizing the fact that the copper tube coil is exposed to high temperature during heating and annealing, the inner surface lubricating oil in the copper tube coil is vaporized and removed, but it is not possible to remove the residual oil in the tube over the entire length. Have difficulty. Therefore, with hydrocarbon-based internal lubricating oil, the residual oil is randomly distributed in the pipe, and when brazing the copper pipe coil in the assembly of a heat exchanger, etc., this residual oil causes the brazing failure. May occur. Therefore, in order to reduce the residual oil on the inner surface of the copper tube coil, it has been attempted to reduce the viscosity of the hydrocarbon-based lubricating oil and thin the oil film on the inner surface of the tube.

As another residual oil removal method, nitrogen gas or an inert gas is supplied into the copper tube coil during heating and annealing,
A method of purging the vaporized residual oil has been proposed (JP-A-5-57263 and JP-A-54-48620).

[0004]

However, the above-mentioned prior art has the following problems. That is, the complete pyrolysis temperature of a hydrocarbon-based oil is 40 in an inert gas.
The temperature exceeds 0 ° C and is close to the softening temperature of the copper tube. Therefore, due to the uneven temperature distribution of the copper tube coil in the annealing furnace, the oil locally condenses and is concentrated by several tens to several hundreds of times, and a portion where the concentrated oil remains in the coil occurs. Therefore, there is a problem that low residual oil cannot be realized over the entire length of the coil.

Recently, to protect the environment, HFC (Hy
Freon gas of drofluorocarbon type is being used as a refrigerant. When a copper pipe coil is processed and a heat exchanger such as an air conditioner and a refrigerator is manufactured with the hydrocarbon-based residual oil remaining, the HFC-based refrigerant is not compatible with the hydrocarbon-based oil, so the refrigeration system However, there is a problem in that the operation of the vehicle is hindered and the capillaries are clogged due to contamination.

Further, the method of purging the residual oil in the copper tube coil in the furnace has the problems of extremely low productivity, high cost, and vaporized oil polluting the environment. In addition, there is a problem that oxidation and discoloration easily occur on the inner surface of the coil because the residual oil in the coil is reduced. Furthermore, in order to carry out this method, it is necessary to modify the existing annealing furnace, which has the disadvantage of requiring additional investment.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a copper tube coil having a small amount of residual oil on the inner surface of the tube.

[0008]

A method of manufacturing a copper pipe coil according to the present invention is a copper pipe coil obtained by winding a copper pipe obtained through one or more drawing steps into a copper pipe coil. In the method for producing a copper pipe coil in which a coil is heat-treated in a heat treatment furnace without passing gas through the pipe, a water-insoluble polyalkylene glycol is used as an inner surface lubricating oil from a predetermined drawing process to a final drawing process among the drawing processes. use,
It is characterized in that the water-insoluble polyalkylene glycol is thermally decomposed by the heat treatment.

Another method of manufacturing a copper pipe coil according to the present invention is that a copper pipe obtained through one or a plurality of drawing steps is subjected to intermediate annealing, then the inner surface of the copper pipe is grooved, and then wound. To make a copper pipe coil, and pass this copper pipe coil through the gas.
In a method for producing a copper pipe coil which is heat-treated in a heat-treating furnace without flowing, a water-insoluble polyalkylene glycol is used as an inner surface lubricating oil for the grooving, and the water-insoluble polyalkylene glycol is thermally decomposed by the heat treatment. It is characterized by In this case, a water-insoluble polyalkylene glycol is used as the inner surface lubricating oil from the predetermined drawing step to the final drawing step in the drawing step ,
During annealing and this <br/> to heat treatment without flow through the gas pipe is preferred.

In any of the methods for producing a copper tube coil, the viscosity of the water-insoluble polyalkylene glycol is 2
It is preferably from 00 to 2500 cSt.

Further, it is preferable that benzotriazole is dissolved in the water-insoluble polyalkylene glycol in an amount of 0.05 to 3.0% by weight.

Further, after the heat treatment, it is preferable to replace the inside of the copper tube coil with an inert gas.

Further, the water-insoluble polyalkylene glycol is preferably compatible with HFC-based CFCs.

Further, the water-insoluble polyalkylene glycol preferably further contains a higher alcohol: 10% by weight or less.

[0015]

As a result of various experiments and studies, the inventors of the present invention have found that if a water-insoluble polyalkylene glycol having a low thermal decomposition temperature in an inert gas atmosphere is used as a lubricating oil for pipe inner surface, the lubricating oil is thermally decomposed during heat treatment. It was found that a copper tube coil which is removed by the above method and has little residual oil over the entire length can be obtained.

In the method for manufacturing a copper tube coil according to the present invention, a copper tube is obtained by performing drawing one or more times to obtain a copper tube, and the copper tube is wound into a coil to form a copper tube coil. Next, this copper tube coil is placed in a heat treatment furnace and heat treated. In this case, from the predetermined drawing step to the final drawing step, a water-insoluble polyalkylene glycol as an inner surface lubricating oil is applied to the inner surface of the copper pipe, and the copper pipe is drawn. Then, the complete thermal decomposition temperature of the water-insoluble polyalkylene glycol is extremely low as compared with the complete thermal decomposition temperature of the hydrocarbon-based oil,
The water-insoluble polyalkylene glycol is thermally decomposed in the copper tube coil during heat treatment. Therefore, in the cooling process, since the lubricating oil does not exist as a gas component in the pipe, the lubricating oil does not condense at the low temperature portion of the inner surface of the pipe and the oil does not concentrate at this portion. As a result, low residual oil can be achieved over the entire length of the coil.

When the drawing process using the water-insoluble polyalkylene glycol is only one process, the predetermined drawing process to the final drawing process means the final drawing process. Since the water-insoluble polyalkylene glycol is expensive as compared with the conventional hydrocarbon-based oil, application of it to the entire drawing process causes an increase in cost. For this reason,
The water-insoluble polyalkylene glycol may be used only in the final drawing step and conventional oil may be used in the other drawing steps.

When a water-insoluble polyalkylene glycol is used as the inner surface lubricating oil in a plurality of drawing steps including the final step, a processing oil other than the water-insoluble polyalkylene glycol is used in the previous step. Even when the copper pipe remains in the copper pipe, the drawing oil is drawn from the predetermined drawing process to the final drawing process using the water-insoluble polyalkylene glycol, so that the processing oil other than the water-insoluble polyalkylene glycol in the copper pipe is reduced. As a result, when a copper tube is wound into a coil to form a copper tube coil, and this copper tube coil is placed in a heat treatment furnace and heat treated, the components of the lubricating oil in the coil are substantially water-insoluble polyalkylene. Since it becomes glycol, the residual oil in the pipe is further removed.

When the above-mentioned heat treatment is applied to a copper tube coil, the inside of the copper tube coil is usually DX gas (CO: 2 to 3 volume%, H ₂ : 2 to 3 volume%, CO ₂ : 10 to 12 volume). % and N _2: after purging with an inert gas such as balance) or a nitrogen gas, heat treatment to the coil at DX gas atmosphere. However, the purge gas and the atmosphere gas are not limited to this.

In another method for manufacturing a copper tube coil according to the present invention, a copper tube is obtained by performing drawing one or more times, then the copper tube is annealed and then grooved. In this case,
The water-insoluble polyalkylene glycol described above is applied to the inner surface of the copper pipe as an inner surface lubricating oil, and then grooved. The obtained copper tube is wound into a coil to form a copper tube coil, and the copper tube coil is placed in a heat treatment furnace and heat treated. Then, similar to the above-described method for producing a copper tube coil, the water-insoluble polyalkylene glycol is thermally decomposed in the copper tube coil during the heat treatment and does not condense at a low temperature portion on the inner surface of the tube during the cooling process. As a result, low residual oil can be achieved over the entire length of the copper pipe coil having the groove formed on the inner surface.

In addition to grooving, when a water-insoluble polyalkylene glycol is used as the lubricating oil in the predetermined drawing process to the final drawing process, the tempering of the copper pipe is adjusted during the intermediate annealing and The water-insoluble polyalkylene glycol of is thermally decomposed and removed. As a result, when the copper pipe is wound into a coil to form a copper pipe coil, and the copper pipe coil is charged into a heat treatment furnace and subjected to heat treatment, residual oil is further removed over the entire length of the coil.

An induction heater (induction heating furnace) is usually used for the above-mentioned intermediate annealing. When intermediate annealing is performed with an induction heater, the heating time is as short as several seconds, so the water-insoluble polyalkylene glycol used in the drawing step preferably has a low thermal decomposition temperature.

In any of the above-mentioned copper tube coil manufacturing methods, a water-insoluble polyalkylene glycol is used as the inner surface lubricating oil. The complete decomposition temperature of the water-insoluble polyalkylene glycol in the inert gas is about 50 ° C lower than the complete decomposition temperature of the water-soluble polyalkylene glycol. Therefore, the water-insoluble polyalkylene glycol is easily decomposed by heat and does not remain in the coil. On the other hand, since water-soluble polyalkylene glycol easily absorbs water, discoloration and corrosion of the inner surface of the coil due to water absorption poses a problem. Therefore, in the present invention, a water-insoluble polyalkylene glycol is used as a lubricating oil.

The water-insoluble polyalkylene glycol is P
A polymer of O (propylene oxide) and EO (ethylene oxide), which has a high proportion of PO and a linear structure, has a low thermal decomposition temperature and a small amount of residual oil in the pipe after heating the copper pipe coil.

The water-insoluble polyalkylene glycol has a temperature at which its complete thermal decomposition is substantially constant regardless of the viscosity (molecular weight), and is a temperature-dependent type. For this reason, even when the water-insoluble polyalkylene glycol is adjusted to have various viscosities, the water-insoluble polyalkylene glycol is completely decomposed by heating, so that the amount of residual oil in the copper pipe coil after annealing largely changes. There is no such thing. Therefore, the viscosity of the water-insoluble polyalkylene glycol can be adjusted according to the drawing load, but the viscosity is preferably 200 to 2500 cSt. The lubrication of the inner surface of the copper pipe during drawing is dominated by the thickness of the oil film. When performing drawing with a high processing rate, the viscosity is 2000 in order to maintain the oil film thickness.
To 2500 cSt is preferable. However, if the viscosity exceeds 2500 cSt, the oil film becomes too thick,
As the consumption of water-insoluble polyalkylene glycol increases, the load on the infusion pump increases due to viscous resistance.

On the other hand, when the drawing rate is low,
Although a low-viscosity water-insoluble polyalkylene glycol can be used, when the viscosity is less than 200 cSt, the fluidity becomes too large, and the tip is shrunk during the pointing operation (the tip of the copper tube is passed through the die. Diameter.)
Moreover, oil leaks from the inside of the pipe, and the oil film becomes too thin, and the copper pipe easily breaks. Therefore, the water-insoluble polyalkylene glycol has a viscosity of 200 to 2500 cS.
It is preferably t. Note that cSt (centistoke) is a unit of viscosity and is 1 m ² s ⁻¹ = 10 ⁴ St = 10.
⁶ cSt.

When a copper pipe is drawn by using a water-insoluble polyalkylene glycol as the inner surface lubricating oil, the residual oil on the inner surface of the pipe is reduced and the residual carbon content is reduced, so that an extremely clean inner surface can be obtained. . However, this increases the susceptibility of the inner surface of the tube to oxidation and discoloration. Therefore, when the copper pipe coil is stored in a warehouse after heat treatment, a temperature difference between the inside and outside of the coil causes a pressure difference between the inside and outside of the pipe, and this pressure difference causes gas to flow in and out of the pipe. There is a risk that the gas in the tube will be replaced by the outside air by the breathing action, and oxidation and discoloration will occur on the inner surface of the tube. Oxidation and discoloration of the inner surface of the pipe due to this breathing action also occur when nitrogen gas or an inert gas is supplied into the copper pipe coil during heating and annealing, and the vaporized residual oil is purged to remove the residual oil on the inner surface of the pipe. Therefore, it is preferable to take some measures.

Therefore, it is preferable to form an oxidation protection film on the inner surface of the copper tube as described below. That is, benzotriazole, which is a vaporization rust inhibitor such as copper, is dissolved and added to a water-insoluble polyalkylene glycol. Then, the benzotriazole is vaporized from the water-insoluble polyalkylene glycol by heating during the heat treatment. When benzotriazole vaporizes due to heating during heat treatment in an atmosphere gas such as nitrogen gas and is condensed and adheres to the inside of the tube, the rustproofing effect of benzotriazole becomes extremely small. However, since the water-insoluble polyalkylene glycol adheres to the inner surface of the tube during heating, benzotriazole does not adhere to the inner surface of the tube. When the water-insoluble polyalkylene glycol on the inner surface of the pipe is completely decomposed and the clean surface of the inner surface of the copper pipe is exposed, the copper pipe is cooled, and during this cooling, benzotriazole adheres to the clean surface and an antioxidant protective film is formed. It is formed. By attaching the benzotriazole to the inner surface of the tube at a low temperature in this way, a strong antioxidative protective film can be obtained, and discoloration of the inner surface of the tube can be prevented for a long period of time.

Since the lubrication in the pipe during drawing of the copper pipe depends on the oil film thickness, it is preferable to change the total amount of benzotriazole dissolved and added according to the viscosity of the water-insoluble polyalkylene glycol used. That is, the optimal benzotriazole content depends on the viscosity of the water-insoluble polyalkylene glycol. In order to effectively prevent the inner surface of the pipe from rusting with benzotriazole, when the water-insoluble polyalkylene glycol has a viscosity of 2500 cSt, the amount of benzotriazole dissolved and added is preferably 0.05% by weight or more. On the other hand, when the viscosity of the water-insoluble polyalkylene glycol is 200 cSt, the amount of benzotriazole dissolved and added is preferably 2.0% by weight or less, and 3.0% by weight in consideration of the variation in quality during production. % Or less is preferable. Therefore, when the benzotriazole is dissolved and added to the water-insoluble polyalkylene glycol, the amount of the dissolved addition is preferably 0.05 to 3.0% by weight.

Although benzotriazole is soluble in the water-insoluble polyalkylene glycol, in order to dissolve it more uniformly, the benzotriazole is dissolved while heating the water-insoluble polyalkylene glycol at a temperature of 50 to 60 ° C. Add and stir.

Further, the film formed by benzotriazole is extremely thin and does not adversely affect the bending and expanding processing of the copper tube and the processing such as brazing, but an excessive amount of benzo is contained in the tube of the copper tube coil after cooling. When the triazole gas remains, the benzotriazole gas crystallizes to form a solid. Such a solid matter may cause a problem when a copper tube coil is expanded and bent to manufacture a heat exchanger or the like. Further, when the obtained heat exchanger is actually used, this solid substance is vaporized to become a non-condensed gas, which may adversely affect the refrigeration system. Therefore, after the heat treatment is completed, it is preferable to supply an inert gas such as nitrogen gas into the inside of the copper tube coil to replace the inside of the tube to prevent crystallization of benzotriazole and to prevent the formation of solid matter.

The water-insoluble polyalkylene glycol is H
It is preferable that it is compatible with FC type CFCs. In such a water-insoluble polyalkylene glycol, when a copper tube coil is processed and used as a tube of a heat exchanger, even when the water-insoluble polyalkylene glycol remains in the tube, Since the water-insoluble polyalkylene glycol is compatible with the Freon of the refrigerant, it is possible to prevent contamination in the tube.

The viscosity of the water-insoluble polyalkylene glycol can be variously changed by changing its molecular weight, but when a large number of copper pipe coils are produced, the viscosity is adjusted by a viscosity modifier. Is economical. As the viscosity adjusting rust agent, it is preferable to use a higher alcohol compatible with the water-insoluble polyalkylene glycol. However, if the content of higher alcohol exceeds 10% by weight, the amount of residual oil remaining in the pipe of the copper pipe coil increases. Therefore, when a higher alcohol is made compatible with the water-insoluble polyalkylene glycol, the content thereof is preferably 10% by weight or less.

[0034]

The method for manufacturing a copper tube coil according to the present invention will be further described below. First, the heat treatment furnace (roller hearth furnace) will be described. FIG. 1 is a schematic view showing a roller hearth furnace. As shown in FIG. 1, the roller hearth furnace includes an inlet side vestibule 25a, a heating zone 26, a cooling zone 27 and an outlet side vestibule 25b. The entrance vestibule 25a is a room that prevents the atmosphere from entering the heating zone 26, and the exit vestibule 25b is a room that prevents the atmosphere from entering the cooling zone 27.
A copper tube coil 61 is loaded in the roller hearth furnace.
The copper tube coil 61 is heat-annealed in the heating zone 26 after passing through the entrance side vestibule 25 a, and then the cooling zone 27.
After being cooled in, it passes through the outlet vestibule 25b,
It is sent out of the furnace.

Next, the characteristics of the conventional hydrocarbon-based lubricating oil will be described. FIG. 2 is a graph showing the relationship between the temperature (° C.) on the horizontal axis and the thermal decomposition characteristic (% by weight) on the vertical axis. This measurement was performed by using a nitrogen atmosphere as an atmosphere, preparing a hydrocarbon-based oil having a viscosity of 1000 cSt, and raising the temperature of this oil at 10 ° C./min. As shown in FIG. 2, the complete pyrolysis temperature of the hydrocarbon-based oil is 400 ° C. or higher in the inert gas atmosphere. Further, the viscosity of this oil was changed and the same measurement was carried out, but the complete thermal decomposition temperatures were all 400 ° C. or higher. When such an oil is applied to the inner surface of the copper tube coil 61 as the inner surface lubricating oil and the copper tube coil 61 is heated or cooled in the roller hearth furnace, the temperature of the copper tube coil 61 varies greatly depending on the coil portion. , A temperature difference occurs in the coil.

FIG. 3 is a graph showing the relationship between the time (minutes) on the horizontal axis and the temperature at each part of the copper tube coil 61 on the vertical axis. In addition, reference numerals 51 to 5 of the graph
5 shows each part of the copper tube coil 61, and FIG. 4 is a sectional view showing each part of the copper tube coil 61. As shown in FIG.
Reference numeral 51 in FIG. 3 indicates the hollow portion upper portion 51 of the copper tube coil 61, and reference numerals 52 to 54 in FIG. 3 respectively indicate the copper tube coil 61.
The outer peripheral central portion 52, the inner central portion 53, and the inner peripheral central portion 54 are shown, and the reference numeral 55 in FIG. As shown in FIG. 3, each part is a heating zone 2 of a roller hearth furnace.
It is heated at 6 and reaches a high temperature. Each part is cooled when it enters the cooling zone 27, but the temperature of the inner central part 53 is 450 ° C.
Even if it exceeds, the temperature of the central portion 55 of the lower surface is already 100
It is cooled down to about ℃. That is, even when the lubricating oil in the inner central portion 53 and the like is exposed to a high temperature and evaporates, the temperatures of the lower surface central portion 55 and the outer peripheral central portion 52 have already dropped. Therefore, when the complete thermal decomposition temperature of the inner surface lubricating oil is high as described above, the evaporated lubricating oil moves in the pipe and is recondensed in the low temperature portion before being completely thermally decomposed. For this reason, the evaporated lubricating oil concentrates in the low temperature part, and an extremely high-concentration residual oil remains in the low temperature part.

FIG. 5 is a graph showing the relationship between the water-insoluble polyalkylene glycols of various viscosities, with the horizontal axis representing temperature (° C.) and the vertical axis representing thermal decomposition characteristics (wt%). . Reference numerals 81 to 83 in the figure each have a viscosity of 5
00cSt, 1000cSt, 1500cSt are shown. Further, this measurement was carried out in a nitrogen atmosphere under the condition that the temperature rising rate was 10 ° C./min.

As shown in FIG. 5, the water-insoluble polyalkylene glycol is completely decomposed at a temperature of around 350 ° C. in an inert gas atmosphere, and the residual component after decomposition is extremely small. . As described above, since the complete thermal decomposition temperature of the water-insoluble polyalkylene glycol is extremely lower than the complete thermal decomposition temperature of the hydrocarbon-based oil, this water-insoluble polyalkylene glycol is applied to the inner surface of the copper tube coil 61. If yes, heating zone 2
At 6, the thermal decomposition of the lubricating oil is completed. Therefore, the oil is not cooled and condensed in the cooling zone 27, and the oil is not concentrated on a specific portion in the copper tube coil 61. As a result, low residual oil can be achieved over the entire length of the coil.

Next, examples of the present invention will be described.
A water-insoluble polyalkylene glycol having a viscosity of 1000 cSt was used for the second drawing (the final drawing step and the drawing step before it) to draw a phosphorus deoxidized copper tube, and the outer diameter was 9.5.
A smooth copper tube having a thickness of 2 mm and a thickness of 0.3 mm was used. Next, this smooth copper tube was wound to form a copper tube coil having a weight of 135 kg, and residual gas in the tube was purged with DX gas, and then this copper tube coil was loaded into a roller hearth furnace in a DX gas atmosphere, The atmosphere gas temperature was set to 630 ° C., the material was heated and annealed, then cooled, and the temper was set to OL. After the residual gas in the cooled copper tube coil was replaced with nitrogen gas, the copper tube coil was disassembled and samples were taken from each site in the tube. The obtained sample was washed and collected with Freon (R141b), and the residual oil weight was measured. FIG. 6 is a cross-sectional view showing each part.
As shown in FIG. 6, 15 sites (reference numerals 1 to 15 in FIG. 6) were selected from the upper, middle, and lower stages from the outer circumference to the inner circumference of the copper tube coil 61, and samples were taken from the respective sites. .

FIG. 7 is a graph showing the relationship between the two, with the horizontal axis representing the sample number and the vertical axis representing the residual oil weight. As shown in FIG. 7, the residual oil weight was 0.3 mg / m or less at all the sites. That is, it was 0.3 mg / m or less over the entire length of the coil tube. Thus, by using the water-insoluble polyalkylene glycol as the inner surface lubricating oil, a low residual oil can be achieved over the entire length of the coil tube.

Next, 0.3% of benzotriazole was added to water-insoluble polyalkylene glycol having a viscosity of 1000 cSt.
An example in which 3% by weight and 3% by weight of higher alcohol are dissolved and added will be described. This water-insoluble polyalkylene glycol was used for raising and drawing 2 to draw a copper tube to obtain a smooth copper tube having an outer diameter of 9.52 mm and a wall thickness of 0.3 mm. Next, this smooth copper tube was wound up into a copper tube coil having a weight of 132 kg, residual gas in the tube was purged with DX gas, and then this copper tube coil was loaded into a roller hearth furnace in a DX gas atmosphere, The atmosphere gas temperature was set to 630 ° C., the material was heated and annealed, and then cooled. After substituting the residual gas in the copper pipe coil after cooling with nitrogen gas, the pipe was disassembled, a sample was taken from the site shown in FIG. 6, and the obtained sample was washed and collected with Freon (R141b) to measure the residual oil weight. It was measured.

FIG. 8 is a graph showing the relationship between the two, with the horizontal axis representing the sample number and the vertical axis representing the weight of the residual oil. As shown in FIG. 8, the residual oil weight was 0.3 mg / m or less over the entire length of the coil tube regardless of the site.

Next, under the same conditions, 130 to 142 kg.
5 annealed copper pipe coils were prepared, and each copper pipe coil was placed in an environment of 40 ° C and 80% humidity for 12 hours, and then 12 hours in an environment of 25 ° C and 60% humidity. Then, the cycle test was repeated 100 times, and the discoloration of each copper tube coil was investigated. as a result,
Discoloration was recognized on the outer surface of the copper tube inside each coil (copper tube surrounded by the copper tube inside the coil), but discoloration was observed on the inner surface of the coil coated with the water-insoluble polyalkylene glycol of this example. I was not able to admit.

On the other hand, using hydrocarbon-based oil as the inner surface lubricating oil, five 130 to 142 kg annealed copper tube coils were prepared under the same conditions, and as a result of examining the discoloration state of each coil,
In each coil, a strong purple discoloration occurred on the inner surface of the tube near both tube ends.

Further, benzotriazole was added to a hydrocarbon-based oil, this oil was used as an inner surface lubricating oil, the copper tube coil was annealed under the same conditions, and as a result of examining the discoloration state, no discoloration occurred. However, benzotriazole was crystallized at a site where residual oil was concentrated, and a solid product was produced. When such a copper tube coil is used for a tube or the like of a heat exchanger, problems such as contamination occur and there is a practical problem.

From the above, by using the water-insoluble polyalkylene glycol in which benzotriazole is dissolved as the inner surface lubricating oil, the residual oil of the coil tube is reduced and the discoloration of the inner surface of the coil tube is prevented. You can

Next, an embodiment of the inner grooved tube will be described. In recent years, inner grooved tubes have been widely used as tubes for heat exchangers of air conditioners. When the residual oil is present in the inner grooved pipe, the residual oil is concentrated in the groove. Therefore, when a heat exchanger is manufactured by brazing the inner grooved pipe, brazing failure due to residual oil may occur, or this residual oil may vaporize and adversely affect the refrigeration system. It is preferable to reduce the amount beyond the smooth tube. Therefore, in this example, a water-insoluble polyalkylene glycol having a low viscosity was used during the grooving process.

To a water-insoluble polyalkylene glycol having a viscosity of 1000 cSt, 0.3% by weight of benzotriazole and 2% by weight of a higher alcohol were dissolved and added, and the obtained water-insoluble polyalkylene glycol was used as an internal lubricating oil. Then, the copper tube is drawn, and the outer diameter is 12.7 mm,
A copper tube coil (bulb block) having a wall thickness of 0.38 mm was obtained. While purging the inside of this copper tube coil with nitrogen gas,
Continuous annealing was performed with an induction heater using DX gas as the atmosphere gas. Next, benzotriazole was added to 0.
Prepare a water-insoluble polyalkylene glycol (viscosity 300 cSt) dissolved and added at 1% by weight, and apply this water-insoluble polyalkylene glycol to the inner surface of the above-mentioned copper pipe,
Grooving was performed by a grooving device to obtain a copper tube coil having an outer diameter of 9.52 mm, a wall thickness of 0.36 mm and a weight of 135 kg. After the inside of the obtained copper tube coil was purged with DX gas, the atmosphere gas was changed to DX gas and the atmosphere temperature was set to 63.
The copper tube coil was heated and annealed in a roller hearth furnace at 0 ° C., and further cooled. Next, after substituting the residual gas in the copper tube coil with nitrogen gas, the copper tube coil was disassembled, a sample was taken from the site shown in FIG. 6, and the obtained sample was washed with Freon (R141b). After collecting the residual oil, the residual oil weight was measured.

FIG. 9 is a graph showing the relationship between the two, with the horizontal axis representing the sample number and the vertical axis representing the residual oil weight. As shown in FIG. 9, the residual oil weight was 0.2 mg / m or less over the entire length of the coil tube regardless of the site. Thus, in addition to using a low-viscosity water-insoluble polyalkylene glycol (viscosity 300 cSt) as the inner surface lubricating oil to make the oil film extremely thin, the oil film is a thin film,
Due to the improved thermal conductivity from the groove to the oil, even though about twice as much oil as the smooth tube was attached to the inner surface before annealing, about half the residual oil of the smooth tube was obtained after annealing. As the amount of the residual oil, the residual oil could be removed very well.

Next, 131 to 143 kg under the same conditions
5 annealed copper pipe coils were prepared, and each copper pipe coil had a temperature of 40 ° C. and a humidity of 80 as in the case of the smooth copper pipe.
%, A temperature of 25 ° C., a humidity of 60%, a 12-hour cycle test was performed 100 times,
The discoloration situation of each copper tube coil was investigated. As a result, discoloration was observed on the outer surface of the copper tube inside each coil, but no discoloration was observed on the inner surface of the coil coated with the water-insoluble polyalkylene glycol of this example.

On the other hand, using hydrocarbon-based oil as the inner surface lubricating oil, five pieces of 133 to 140 kg annealed copper pipe coils were prepared under the same conditions, and the discoloration of each coil was examined.
In all of the coils, purple discoloration occurred on the inner surface of the tube near both tube ends.

When a coating film is formed from benzotriazole, the coating film is extremely thin, so that it does not adversely affect bending and expanding of the copper tube and brazing of the copper tube. This was actually confirmed.

Further, the water-insoluble polyalkylene glycol in this example was heated in a furnace at an equivalent temperature, and the obtained decomposition product was subjected to a shield tube test. As a result, the water-insoluble polyalkylene glycol was compatible with the HFC-based refrigerant and no contamination occurred.

Next, examples of the present invention will be described in comparison with comparative examples. First, a method for manufacturing a copper tube coil and a method for measuring a residual oil weight in Examples 1 to 7 and Comparative Examples 1 and 2 will be described.

Example 1 0.5% by weight of benzotriazole was dissolved and added to a water-insoluble polyalkylene glycol having a viscosity of 1000 cSt,
This water-insoluble polyalkylene glycol was used as an internal lubricating oil of 2 drawn and a phosphorus deoxidized copper tube was drawn. The obtained copper tube was wound into a coil and had an outer diameter of 9.52 mm,
A smooth copper tube coil having a wall thickness of 0.3 mm and a weight of 135 kg was used. After purging the inside of the copper tube coil with DX gas, the atmosphere gas was changed to DX gas and the atmosphere temperature was set to 63.
The copper tube coil was heated and annealed in a roller hearth furnace at 0 ° C. and then cooled. After the residual gas in the tube was replaced with nitrogen gas, the copper tube coil was disassembled and samples were taken from each part shown in FIG. 6, and each sample was made of CFC (R141b).
The residual oil was weighed after the residual oil was collected by washing with.

Example 2 To a water-insoluble polyalkylene glycol having a viscosity of 1000 cSt, 0.3% by weight of benzotriazole was dissolved and added, and this water-insoluble polyalkylene glycol was used as an internal lubricating oil at the time of drawing and phosphorus. A deoxidized copper tube was drawn. The obtained copper tube was subjected to intermediate annealing with an induction heater. 0.5% by weight of benzotriazole was dissolved and added to a water-insoluble polyalkylene glycol having a viscosity of 350 cSt, and the water-insoluble polyalkylene glycol was used as an inner surface lubricating oil to form a groove on the inner surface of the copper pipe after the intermediate annealing. Was applied. The grooved copper tube obtained was wound into a coil, and the outer diameter was 7.0 mm, the average wall thickness was 0.3 mm, and the weight was 140 mm.
After making a copper pipe coil with a groove of kg, purging the inside of this coil with DX gas, setting the atmosphere gas to DX gas, setting the atmosphere temperature to 630 ° C., heating and annealing this coil in a roller hearth furnace, Cooled. After replacing the residual gas in the pipe with nitrogen gas, dismantling the grooved copper pipe coil, collecting samples from each site shown in FIG. 6, washing each sample with Freon (R141b), and collecting residual oil The residual oil weight was measured.

Example 3 A non-water-soluble polyalkylene glycol having a viscosity of 120 cSt was used as an inner surface lubricating oil during drawing and was drawn to obtain a phosphorus-deoxidized copper smooth tube having an outer diameter of 9.52 mm and a wall thickness of 0.3 mm. It was However, because the oil film thickness of the lubricating oil was insufficient,
The plug was pumped, the pipe broke, and drawing was extremely difficult. Therefore, the residual oil weight was not measured.

Example 4 A phosphorus-deoxidized copper tube was drawn by using a water-insoluble polyalkylene glycol having a viscosity of 3500 cSt as an internal lubricating oil for drawing. The obtained copper tube was wound into a coil, the outer diameter was 9.52 mm, the wall thickness was 0.3 mm, and the weight was 1.
A 38 kg smooth copper tube coil was used. After the inside of the copper tube coil was purged with DX gas, the atmosphere gas was set to DX gas, the atmosphere temperature was set to 630 ° C., the copper tube coil was heated and annealed in a roller hearth furnace, and then cooled. After replacing the residual gas in the pipe with nitrogen gas, the copper pipe coil was disassembled, samples were taken from each part shown in FIG. 6, and each sample was washed with Freon (R141b) to collect the residual oil. The oil weight was measured.

Example 5 0.03% by weight of benzotriazole was dissolved and added to a water-insoluble polyalkylene glycol having a viscosity of 2500 cSt, and this was used as an internal lubricating oil for drawing and drawing a phosphorus deoxidized copper pipe. did. The obtained copper tube was wound into a coil, the outer diameter was 9.52 mm, the wall thickness was 0.3 mm, and the weight was 1.
It was a smooth copper tube coil of 42 kg. After the inside of the copper tube coil was purged with DX gas, the atmosphere gas was set to DX gas, the atmosphere temperature was set to 630 ° C., the copper tube coil was heated and annealed in a roller hearth furnace, and then cooled. After replacing the residual gas in the pipe with nitrogen gas, the copper pipe coil was disassembled, samples were taken from each part shown in FIG. 6, and each sample was washed with Freon (R141b) to collect the residual oil. The oil weight was measured.

Example 6 3.50% by weight of benzotriazole was dissolved and added to a water-insoluble polyalkylene glycol having a viscosity of 200 cSt, and this was used as an internal lubricating oil for drawing and drawing a phosphorus deoxidized copper pipe. did. In the same manner as in Example 5, the obtained copper pipe was wound into a coil to form a smooth copper pipe coil, which was annealed by heating and then disassembled to measure the residual oil weight.

Example 7 15% by weight of a higher alcohol (octyl alcohol) was dissolved and added to a water-insoluble polyalkylene glycol having a viscosity of 2500 cSt, and this was used as an inner surface lubricating oil for ascending drawing, and a phosphorus deoxidized copper pipe was used. Was drawn. Similar to Example 5,
The obtained copper pipe was wound into a coil to form a smooth copper pipe coil, which was annealed by heating and then disassembled to measure the residual oil weight.

Comparative Example 1 A polybutene-based inner surface lubricating oil having a viscosity of 1000 cSt was used in all drawing steps, and a phosphorus deoxidized copper tube was drawn.
Next, the obtained phosphorous deoxidized copper tube was wound into a coil shape, the outer diameter was 9.52 mm, the wall thickness was 0.3 mm, and the weight was 137 k.
g copper tube coil, and after the inside of the copper tube coil was purged with DX gas, the atmosphere gas was DX gas, the ambient temperature was 630 ° C., the copper tube coil was heated and annealed in a roller hearth furnace, and cooled. . After replacing the residual gas in the tube with nitrogen gas, the copper tube coil was disassembled, samples were taken from each site shown in FIG. 6, and each sample was made into fluorocarbon (R141
After the residual oil was collected by washing in b), the residual oil weight was measured.

Comparative Example 2 A polybutene-based inner lubricating oil having a viscosity of 500 cSt was drawn after drawing a phosphorus deoxidized copper pipe using an inner lubricating oil of a polybutene base having a viscosity of 1000 cSt, and then performing intermediate annealing with an induction heater. And used as a groove. The grooved copper tube obtained was wound into a coil, and the outer diameter was 7.0 mm, the average wall thickness was 0.3 mm, and the weight was 138 kg.
The inner surface of the copper tube coil with groove. After purging the inside of the obtained copper tube coil with DX gas, the atmosphere gas was set to DX gas, the atmospheric temperature was set to 630 ° C., and the copper tube coil was annealed by heating in a roller hearth furnace and cooled. After replacing the residual gas in the tube with nitrogen gas, the copper tube coil was disassembled, and as shown in FIG.
Samples were taken from the respective sites shown in 1), each sample was washed with Freon (R141b) to collect the residual oil, and then the residual oil weight was measured.

The residual oil weights of Examples 1 to 7 and Comparative Examples 1 and 2 are shown in Table 1 below.

[0065]

[Table 1]

Next, for each of the copper tube coils of Examples 1, 2, 4, 5 and Comparative Examples 1, 2, the temperature was 40 ° C. and the humidity was 8
Under the condition of 0%, the temperature of 25 ° C. and the humidity of 60%, a 12-hour cycle test was carried out a plurality of times, and the discoloration state of each copper tube coil at the number of cycles of 10, 30, 100 and 150 was investigated. . The results are shown in Table 2 below.

Note that, in Example 3, the discoloration acceleration test was not conducted because the drawing process was defective. In addition, in Examples 6 and 7, the discoloration acceleration test was not performed because the residual oil was large.

[0068]

[Table 2]

As shown in Tables 1 and 2 above, Example 1,
In No. 2, the residual oil amount was extremely small. In addition, discoloration did not occur on the inner surface of the tube.

In Example 3, although drawing is difficult because the viscosity of the water-insoluble polyalkylene glycol is less than 200 cSt, the amount of residual oil in the pipe becomes extremely small when heat treatment is performed. In Example 4, since the water-insoluble polyalkylene glycol had a high viscosity of 3500 cSt, the oil film thickness was thick. Therefore, as compared with the case where the viscosity of the water-insoluble polyalkylene glycol was 2500 cSt, the injection amount of the water-insoluble polyalkylene glycol to the inner surface of the copper pipe was about 1.5 times. The residual oil amount of Example 4 was larger than the residual oil amounts of Examples 1 and 2, but was extremely small compared to Comparative Examples 1 and 2. Further, since the rust preventive benzotriazole was not dissolved and added to the water-insoluble polyalkylene glycol, discoloration occurred on the inner surface of the copper tube coil during the cycles of 10 to 30. From the above, although the viscosity of the water-insoluble polyalkylene glycol is not particularly limited, it is preferable to set the viscosity in the range of 200 to 2500 cSt in order to smoothly perform the drawing at low cost.

In Example 5, the amount of residual oil was substantially the same as in Examples 1 and 2, and the amount of residual oil at each site was 0.5 mg / m or less, but the amount of benzotriazole added was 0.03. weight%
Therefore, discoloration occurred on the inner surface of the copper tube coil during the cycle number of 30 to 100. In Example 6, since the amount of benzotriazole added was as large as 3.50% by weight, the benzotriazole that did not form a film was recrystallized, and this recrystallized benzotriazole became a part of the residual oil and the residual oil. The amount increased. Therefore, the amount of residual oil in Example 6 was larger than those in Examples 1 and 2. However, the residual oil amount of Example 6 was smaller than that of Comparative Example 1. From the above, when benzotriazole is dissolved and added to the water-insoluble polyalkylene glycol as a rust preventive, it is preferable to set the addition amount in the range of 0.05 to 3.0% by weight.

In Example 7, the amount of the residual oil was extremely large because the higher alcohol of 15% by weight was added to the water-insoluble polyalkylene glycol. Alcohol has a good vaporization property, but has a problem of thermal decomposability, and therefore recondenses. Therefore, when the alcohol content is high, the residual oil amount is high. From the above, when the higher alcohol is added to the water-insoluble polyalkylene glycol, the addition amount is set to 10% by weight or less.

On the other hand, in Comparative Examples 1 and 2, since the polybutene-based oil was used as the inner surface lubricating oil, the residual oil amount after annealing was extremely large. Further, since the inner surface lubricating oils of Comparative Examples 1 and 2 did not contain a rust preventive agent, all the copper tube coils were discolored during the cycle number of 10 to 30.

[0074]

As described above, according to the present invention,
Since the copper pipe coil is heat-treated by using a water-insoluble polyalkylene glycol as the inner surface lubricating oil, it is possible to obtain a copper pipe coil with an extremely small amount of residual oil in the pipe, and at the same time without adding a step during the heat treatment. Since the inner surface lubricating oil is removed, the copper tube coil can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view showing a roller hearth furnace.

FIG. 2 is a graph showing the relationship between the temperature (° C.) on the horizontal axis and the thermal decomposition characteristic (% by weight) on the vertical axis.

FIG. 3 is a graph showing the relationship between the time (minutes) on the horizontal axis and the temperature at each site of the copper tube coil on the vertical axis.

FIG. 4 is a cross-sectional view showing each part of the copper tube coil.

FIG. 5 is a graph showing the relationship between the two, with the vertical axis representing the thermal decomposition characteristic (% by weight).

FIG. 6 is a cross-sectional view showing each part.

FIG. 7 is a graph showing the relationship between the two, with the horizontal axis representing the sample number and the vertical axis representing the residual oil weight.

FIG. 8 is a graph showing the relationship between the two by taking the sign of the sample on the horizontal axis and the weight of the residual oil on the vertical axis.

FIG. 9 is a graph showing the relationship between the two, with the horizontal axis representing the sample number and the vertical axis representing the weight of the residual oil.

[Explanation of symbols]

1,2,3,4,5,6,7,8,9,10,11,1
2, 13, 14, 15; part 25a; entrance side vestibule 25b; exit side vestibule 26; heating zone 27; cooling zone 51; hollow upper part 52; outer peripheral central part 53; inner central part 54; inner peripheral central part 55; Lower surface central portion 81; viscosity 500 cSt 82; viscosity 1000 cSt 83; viscosity 1500 cSt

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C10N 40:32 C10N 40:32 (72) Inventor Yoshinobu Tsuzaki 65 Hirazawa, Hadano City, Kanagawa Pref. Inside the Hadano Plant, Kamido Steel Works (72) Inventor Takashi Kuriyama 1-2-8 Marunouchi, Chiyoda-ku, Tokyo Kobe Steel Co., Ltd. Tokyo head office (72) Inventor Saeki, 65 Hirazawa 65, Hadano, Kanagawa Pref. 72) Inventor Akinori Tsuchiya 65 Hirazawa, Hadano City, Kanagawa Prefecture, Kanto Steel Works, Ltd., Hadano Plant (72) Inventor, Masahiko Sato 65, Hiranozawa, Hadano City, Kanagawa Prefecture, Ltd., Hadano Plant, Kanto Steel Works (56) References JP-A-53-54159 (JP, A) JP-A-54-48619 (JP, A) JP-A-50-37966 (JP, A) JP-A-53-58413 (JP, A) (58) Fields investigated (In t.Cl. ⁷ , DB name) C21D 9/08 C21D 1/74 C10M 107/34 C22F 1/08 B21C 23/32

Claims (8)

(57) [Claims] 1. A copper tube obtained by one or more drawing steps is wound into a coil to form a copper tube coil, and the copper tube coil is heat-treated in a heat treatment furnace without passing gas through the tube. In the method for manufacturing a copper tube coil, using a water-insoluble polyalkylene glycol as an inner surface lubricating oil from a predetermined drawing step to a final drawing step among the drawing steps,
A method for producing a copper tube coil, characterized in that the water-insoluble polyalkylene glycol is thermally decomposed by the heat treatment. Wherein one or several times of drawing steps the intermediate copper tube obtained through the annealing and then after processing grooved said copper inner surface, wound and copper tube coil, tube and the copper tube coil
In the method for producing a copper pipe coil which is heat-treated in a heat-treating furnace without causing gas to flow therethrough , a water-insoluble polyalkylene glycol is used as an inner surface lubricating oil for the groove processing, and the water-insoluble polyalkylene glycol is obtained by the heat treatment. A method for producing a copper tube coil, which comprises thermally decomposing a copper. 3. A water-insoluble polyalkylene glycol is used as an inner surface lubricating oil from a predetermined drawing step to a final drawing step in the drawing step, and the intermediate annealing is performed by using a gas in a pipe.
The method for manufacturing a copper tube coil according to claim 2, wherein the heat treatment is performed without passing through. 4. The method for producing a copper tube coil according to claim 1, wherein the water-insoluble polyalkylene glycol has a viscosity of 200 to 2500 cSt. 5. The method for producing a copper tube coil according to claim 4, wherein benzotriazole is dissolved in the water-insoluble polyalkylene glycol in an amount of 0.05 to 3.0% by weight. 6. The method for producing a copper tube coil according to claim 5, wherein the inside of the copper tube coil is replaced with an inert gas after the heat treatment. 7. The copper pipe coil according to claim 1, wherein the water-insoluble polyalkylene glycol is compatible with HFC-based CFCs. Method. 8. The method for producing a copper tube coil according to claim 1, wherein the water-insoluble polyalkylene glycol further contains 10% by weight or less of a higher alcohol.