JPH0959721A - Heat treatment of metallic tubular coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove primary working oil in a coil by fitting a non-return valve at one end of a metallic tubular coil, replacing the inner part of the coil with inert gas, connecting a vessel incorporating silicone oil to the other end of the coil and executing heat treatment. SOLUTION: The metallic tubular coil 1 and the vessel 3 incorporating the silicone oil on a tray 4 are connected through a three-way valve 2, and the non-return valve is fitted to the other end of the metallic tubular coil 1. A valve out of the three-way valve 2 which is not connected to the vessel 3 is connected with an inert gas tank, and the inert gas is supplied into the metallic tubular coil 1 and the air in the coil 1 is replaced. The three-way valve 2 is changed over and the vessel 3 and the coil 1 are made to communicated with each other, and the tray 4 is supplied into a continuous heat treatment furnace. The temp. of working oil in the coil 1 is raised and the oil is vaporized and the silicone oil in the vessel 3 is vaporized, too and flows to the coil 1 and the vaporized primary working oil is discharged outside the tube, and the tray 4 is made to enter a cooling furnace. The silicone oil is liquefied and stuck on the inner wall of the coil 1 to produce the secondary working oil, and since there is the non-return valve, the air does not flow back in the coil 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for a metal tube coil used for a heat exchanger of an air conditioner, a construction pipe, etc., and particularly to reduce the processing oil remaining in the metal tube coil after the heat treatment, The present invention relates to a heat treatment method for a metal tube coil which improves workability in bending and expanding the tube coil.

[0002]

2. Description of the Related Art Conventionally, a metal pipe coil used for a heat exchanger of an air conditioner, a construction pipe, etc., is obtained by extruding a metal ingot and then performing a drawing process to obtain a metal pipe, which is formed into a coil shape. Is being manufactured. In this manufacturing process, when plastic working is performed, processing oil such as polybutene (hereinafter, this processing oil is referred to as primary processing oil) is used, and this primary processing oil remains in the metal tube coil until the end. This remaining primary processing oil later causes corrosion of the metal tube coil and has a great adverse effect on the subsequent process such as brazing. Therefore, the primary processing oil is removed from the metal tube coil before it is supplied to the subsequent process. It is necessary to.

Therefore, after the metal pipe is processed into a coil to form a metal pipe coil, when the metal pipe coil is heat-treated, an inert gas is blown into the metal pipe coil and the primary processing oil together with the inert gas. Is discharged to the outside of the metal tube coil (Japanese Patent Application Laid-Open No. 5-57263 and Japanese Patent Application Laid-Open No. 54-48620).
Japanese Laid-Open Patent Publication No. 1993-242242), or a method of absorbing primary processing oil from one end of a metal tube coil with a vacuum pump.

[0004]

However, the above-mentioned prior art has the following problems. That is, in the method of absorbing with a vacuum pump, it is necessary to place the metal tube coil in vacuum, and it is necessary to perform vacuum suction for every several coils, so continuous processing cannot be performed,
There is a problem that the workability is lowered and a batch type vacuum furnace is required, which increases the equipment cost.

Further, the method of annealing while blowing an inert gas or the like into the metal tube coil (JP-A-5-57263 and JP-A-54-48620) has the following problems. That is, if the temperature and humidity are high after the air in the metal tube coil is removed (purged) by an inert gas and further heat-treated, there is a drawback that discoloration is likely to occur in the metal tube coil. When the metal tube coil is used for an air heat exchanger such as an air conditioner, processing oil (hereinafter, this processing oil is referred to as secondary processing oil) is newly added for lubrication at the time of secondary processing of bending and expansion. It is necessary to apply the oil to the secondary processing oil, and it is also necessary to remove the secondary processing oil. However, in the heat treatment of the heat exchanger, which is implemented as a removing means,
Insufficient removal of residual secondary processing oil.

As described above, according to the conventional method, although the primary processing oil can be removed when the metal tube coil is processed, the work is complicated and the discoloration may occur in the metal tube coil. There is also a problem that the residual oil of the secondary processing oil after the secondary processing is not sufficiently removed.

The present invention has been made in view of the above problems, and the primary processing oil remaining in the metal tube coil can be easily removed, and the secondary processing which has been indispensable in the secondary processing has been conventionally required. An object of the present invention is to provide a heat treatment method for a metal tube coil, which can improve workability by eliminating application of processing oil and can prevent discoloration in the tube.

[0008]

In the heat treatment method for a metal tube coil according to the present invention, a check valve is attached to one end of the metal tube coil, and then an inert gas is supplied to the inside from the other end of the metal tube coil. Then, the air inside the metal tube coil is discharged through a check valve to replace the inside of the metal tube coil with an inert gas atmosphere, and then a container containing silicone oil is connected to the other end, The tube coil is heat treated together with the container.

The kinematic viscosity of the silicone oil is preferably 10 to 5000 centistokes.

[0010]

In the heat treatment method for a metal tube coil according to the present invention, after the check valve is attached to one end of the metal tube coil whose inner wall is coated with the primary processing oil, the metal pipe coil is not inserted into the metal tube coil from the other end. The active gas is supplied, the air in the metal tube coil is discharged through the check valve, and the inside of the metal tube coil is replaced with an inert gas atmosphere. Then, after the container containing the silicone oil and the other end of the metal tube coil described above are connected, they are heat-treated by, for example, charging them in a heat treatment furnace while they are connected to each other.

Then, as the temperature inside the heat treatment furnace rises, the silicone oil in the container evaporates and the pressure rises. Further, the primary processing oil remaining in the metal tube coil also evaporates as the temperature rises. When the silicone oil in the container evaporates and the volume expands, the vapor of silicon flows into the metal tube coil from the container and further flows out of the metal tube coil through the check valve. At this time, the evaporated primary processing oil is also extruded into this silicon vapor and flows out of the metal tube coil through the check valve. By cooling after the heat treatment of the tube, the silicon vapor is condensed and forms a film of silicon oil, which adheres to the inner wall surface of the metal tube coil.

As a result, discoloration due to the exposure of the metal background in the metal tube coil, that is, the formation of an oxide film, is prevented, and at the time of the hairpin bending process and the pipe expanding process when manufacturing the fins coil of an air heat exchanger such as an air conditioner, It is not necessary to newly apply the secondary processing oil to the metal tube coil.

Further, in the present invention, since the check valve is provided for discharging air or steam from the metal tube coil,
The flow direction of the fluid can be one-way from the inside to the outside of the metal tube coil, and even if the temperature of the metal tube coil is slightly high and the silicon film is not sufficiently generated, the outside air (air) will not flow. Since it is possible to prevent the metal tube coil from entering the inside, it is possible to prevent discoloration in the metal tube coil.

The kinematic viscosity of the silicone oil used in the present invention is 10 to 5000 centistokes (10 ^−6).
m ² / s or cSt) is preferable. When silicone oil having such a kinematic viscosity is used, the background of the inner wall of the metal tube coil is not exposed, so discoloration (formation of an oxide film) can be prevented, and during bending and tube expansion processing. It is not necessary to apply the secondary processing oil.
When the kinematic viscosity of the silicone oil is less than 10 centistokes, the lubricating effect of the coating is small, and therefore the lubricating effect of the coating is small during the hairpin bending process and the tube expanding process, which may cause problems such as baking. On the other hand, when the kinematic viscosity of the silicone oil exceeds 5000 centistokes, it becomes difficult to remove the silicone oil in the final step.

[0015]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

First, as shown in FIG. 1, a metal tube coil 1 on a tray 4 and a container 3 containing silicone oil are connected via a three-way valve 2. As a result, one end of the metal tube coil 1 is connected to the container 3 containing the silicone oil via the three-way valve 2. Then, a check valve (not shown in FIG. 1, see FIG. 3) is attached to the other end of the metal tube coil 1. In addition, among the valves of the three-way valve 2, a valve that is not connected to either the metal tube coil 1 or the container 3 is an inert gas tank (not shown) when nitrogen gas is introduced into the metal tube coil 1. ) Is connected to.

With respect to the metal pipe coil 1 on the tray 4 thus constructed, the three-way valve 2 is switched to connect the inert gas tank and the metal pipe coil 1 to each other, and nitrogen gas is supplied to the metal pipe coil 1. . Then, the air in the metal tube coil 1 is expelled by the inert gas and discharged outside the tube through the check valve. As a result, the inside of the metal tube coil 1 is replaced with the inert gas. After that, the three-way valve 2 is switched to connect the container 3 containing the silicone oil and the metal tube coil 1.

Next, with the container 3 and the metal tube coil 1 in communication with each other, the tray 4 on which the container 3 and the metal tube coil 1 are placed is fed to a continuous heat treatment furnace. FIG. 2 is a schematic diagram showing the temperature distribution at each position in the heat treatment furnace. As shown in FIG. 2, in the inlet vestibule 5a, a large amount of inert gas is supplied to expel mixed air,
The tray 4 is fed into the heating zone 6.

Then, the metal tube coil 1 on the tray 4
The processing oil inside evaporates as the temperature rises. At this time, the silicone oil in the container 3 also vaporizes and expands as the temperature rises. For this reason, the pressure in the container 3 becomes high, so the vaporized silicon oil flows from the container 3 into the metal tube coil 1, and the inflowing silicon oil passes through the check valve together with the vaporized primary processing oil. It is discharged outside the pipe.

Next, the tray 4 passes through the heating zone 6 and enters the cooling zone 7. Then, as the temperature of the metal tube coil 1 decreases, the vaporized silicon is liquefied and adheres to the inner wall of the metal tube coil 1 in a film shape. Metal tube coil 1 after cooling
Is sent from the heat treatment furnace after passing through the outlet side vestibule 5b.

As a result, the primary processing oil in the metal tube coil can be easily removed, and the silicon is removed from the metal tube coil 1.
Since it adheres to the inner wall in a film shape, there is an effect that it is not necessary to newly apply the secondary processing oil.

Further, in the method of this embodiment, a check valve is attached to one end of the metal tube coil so that air flows into the metal tube coil when the gas in the metal tube coil flows out of the metal tube coil. Never. FIG. 3 is a schematic diagram showing a check valve connected to one end of a metal tube coil.
As shown in FIG. 3, a gas outlet 11 and a gas outlet 1 are provided inside the check valve 9 connected to one end 8 of the metal tube coil.
The wall 12 is arranged so as to face 1 and the ball valve 10 is arranged between the gas outlet 11 and the wall 12.

In the check valve 9 thus constructed, the ball valve 10 is first pushed by the wall 12 to come into contact with the gas outlet 11, but the internal pressure of the gas in the metal tube coil is Only when the internal pressure becomes higher and the internal pressure becomes higher than the pressure by the wall 12, the ball valve 10 is separated from the gas outlet 11 and the gas in the metal tube coil is discharged to the outside. Therefore, outside air does not flow into the metal pipe.

When the check valve 9 is not connected to the one end 8 of the metal tube coil, the silicon oil in the container 3 shown in FIG. 1 is heated and expanded in the heat treatment furnace, and then cooled after the heating is completed. When contracted by, the outside air flows into the metal tube coil. When the temperature inside the metal tube coil is as high as 70 to 100 ° C. and the inflowing air is humid, there is a risk that discoloration inside the metal tube coil will occur. In the embodiment of the present invention, since the inside of the metal tube coil is covered with the silicon film, the possibility of discoloration inside the tube is extremely low, but when there is a portion with a thin silicon film inside the metal tube coil. However, by providing the check valve, discoloration in the pipe due to the inflow of air can be prevented.

Next, the results (Examples) obtained by actually heat treating the metal tube coil by the method of this Example are as follows.
Description will be made in comparison with a comparative example that departs from the scope of claims.

First, a metal pipe coil (level wound coil) was manufactured by molding a pure copper smooth pipe and a grooved pipe whose composition is specified in JIS H3300 C1220 into a coil shape. This level wound winding is abbreviated as LWC. The manufacturing process for smooth tubes is melting → casting → extrusion → rolling → drawing → LWC, and the manufacturing process for grooved tubes is melting → casting → extrusion → rolling → drawing → annealing → grooved → LW.
It is C. Manufactures two types of smooth pipe and grooved pipe, one with a diameter of 9.52 mm and a weight of 0.35 tons, and one with a diameter of 7 mm and a weight of 0.3 tons. did. In the drawing and grooving processes in the manufacturing process described above, since the polybden lubricant was used as the primary processing oil, the primary processing oil remained in each LWC pipe. Example No. 1 to 4 and Comparative Example No. The diameter, weight and type of each LWC in 1 to 8 are shown in Table 1 below.

[0027]

[Table 1]

Example No. Each of the LWCs 1 to 4 was heat-treated by the method of the above-described example. A roller hearth type continuous furnace was used as the heat treatment furnace. The temperature in the furnace was about 600 ° C., and the roller feed rate was 270 mm / min. Also, silicone oil is
A kinematic viscosity of 250 centistokes was used.

Next, Comparative Example No. The heat treatment method in 1 to 8 will be described. As the heat treatment furnace, a roller hearth furnace was used as in the above-mentioned examples, and the temperature and feed rate were set to the same conditions as in the examples. Comparative Example No. In 1 to 8, an inert gas was introduced into the LWC instead of the silicone oil. FIG. 4 is a schematic diagram showing a connection state between the LWC 15 and the conduit 16 of the comparative example. As shown in FIG. 4, the conduit 16 having one end connected to the gas pipe 17 has the other end connected to one end of the LWC 15 on the roller 14. Further, the conduit 16 is wound around the winder 13 existing between the gas pipe 17 and the LWC 15, and the length of the conduit 16 can be increased by rotating the winder 13 according to the distance between the gas pipe 17 and the LWC 15. The height can be adjusted.

The LWC 15 is constantly supplied with an inert gas (nitrogen gas) from the conduit 16 while the heat treatment furnace is in progress. As shown in FIG. 2, when the LWC 15 enters the heating zone 6, the LW 15
The primary processed oil in C15 is vaporized, and the primary processed oil is discharged out of the LWC 15 together with the inert gas supplied from the conduit 16.

Example No. 1 obtained as described above. 1
4 and Comparative Example No. Each LWC of 1 to 8 was subjected to bending work and pipe expanding work. Specifically, a heat exchanger used for an air conditioner or the like was manufactured by combining LWC with fins made of aluminum, and in the process, bending and pipe expanding were performed to process the LWC into a caterpillar tube shape. In addition, Comparative Example No. With respect to Nos. 5 to 8, LWC was processed using a secondary processing oil during bending and pipe expanding.

FIG. 5 is a schematic diagram showing a processing procedure of the heat exchanger, and FIG. 6 is a schematic diagram showing how the tube taken from the LWC is expanded. As shown in FIG. 5, the tube 18a collected from the LWC is bent at a bending pitch of 25.4 mm or 21 mm as shown in Table 2 to become the tube 18b, which is fitted into the fin 19 made of aluminum. The tube 18b integrated with the fin 19
Using the core metal 20 as shown in FIG. 6, the tube 18b
Expanded. The pipe expansion rate α was calculated from the following mathematical formula 1.

[0033]

## EQU1 ## Expansion ratio α = {(D ₁ −D ₀ ) / D ₀ } × 100 where D _{0 is} the outer diameter of the tube before the expansion and D _{1 is} the outer diameter of the tube after the expansion.

In the bending process, the case where the tube was wrinkled or fractured was marked with x, and the case where the tube was good without wrinkled or fractured was marked with o. In addition, in the tube expansion process, when the shrinkage of the tube was uneven or buckling occurred, x was given, and when good, it was given as o. Example No. which could be bent. 1 to 4 and Comparative Example No. After heat-treating 5 to 8 with hot air having a temperature of 150 to 180 ° C. for 5 minutes, the remaining amount of the deposits in the tube was measured by the solvent extraction method. The results are shown in Table 2 below.

[0035]

[Table 2]

As is apparent from Table 2 above, Example N
o. 1 to 4 are excellent in bending work and pipe expanding workability,
In addition, the remaining amount of the deposits in the tube was 0.03 to 0.07 mg / m, which was extremely small. On the other hand, in Comparative Example No. Nos. 1 to 4 do not use silicone oil, and 2 when bending
Bending was difficult because no secondary processing oil was used. Comparative Example No. In Nos. 5 to 8, since the secondary processing oil was used during bending and pipe expanding, the bending and pipe expanding could be performed, but the residual amount of deposits in the pipe was 0.58 to 1.15, which was extremely large.

Next, the results of examining the influence of the kinematic viscosity of silicone oil on the workability and the remaining amount of deposits in the pipe will be described. A metal tube coil is manufactured by the same manufacturing method as in the above-mentioned embodiment, and the kinematic viscosity of the silicone oil is 5 to 580.
Each metal tube coil was heat-treated under conditions different from 0 centistokes.

FIG. 7 is a graph showing the relationship between the kinematic viscosity of silicone oil on the horizontal axis and the remaining amount of deposits in the metal tube on the vertical axis. As shown in FIG. 7, when the kinematic viscosity of silicone oil exceeds 5000 centistokes,
Although the pipe expansion and bending are good, the remaining amount of deposits in the pipe exceeds the allowable value of the refrigeration cycle of 0.1 mg / m. Therefore, when the metal tube is used as a caterpillar tube for an air conditioner or the like, the caterpillar tube may be clogged. If the kinematic viscosity of silicone oil is less than 10 centistokes,
Although the amount of deposits in the pipe was small, lubrication was cut off during bending or pipe expansion, causing seizure and shrinkage on the inner surface of the metal pipe.

Although the roller hearth furnace was used as the heating furnace when the metal tube coil was actually heat-treated by the method of this embodiment, a batch furnace can also be used.

[0040]

As described above, according to the present invention,
Since the container containing the silicone oil and one end of the metal tube coil are connected and heat-treated together, the primary processing oil in the metal tube coil can be easily removed. Further, since the silicon film is formed on the inner wall of the metal pipe, post-processes such as bending and expanding of the metal pipe can be performed without using secondary processing oil. Furthermore, since the silicone oil can be easily removed after these processes are completed, workability is greatly improved. Furthermore, since the check valve is installed at one end of the metal tube coil, it is possible to prevent the metal tube coil after the heat treatment from drawing in air and discoloring.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and is a schematic diagram showing a state in which a metal tube coil on a tray and a container containing silicone oil are connected via a three-way valve.

FIG. 2 is a schematic diagram showing a temperature distribution at each position in a heat treatment furnace.

FIG. 3 is a schematic diagram showing a connected state of a metal tube coil and a conduit tube of a comparative example.

FIG. 4 is a schematic diagram showing a processing procedure of a heat exchanger.

FIG. 5 is a schematic diagram showing how a tube taken from a metal tube coil is expanded.

FIG. 6 is a graph showing the relationship between the kinematic viscosity of silicone oil and the remaining amount of deposits in a metal tube.

FIG. 7 is a schematic diagram showing a check valve connected to one end of a metal tube coil.

[Explanation of Codes] 1; Metal tube coil 2; Three-way valve 3; Container 4; Tray 5a; Vestible on input side 5b; Vestible on output side 6; Heating zone 7; Cooling zone 8; One end of metal tube coil 9; Check valve 10; Ball valve 11; Gas outlet 12; Wall 13; Winder 14; Roller 15; LWC 16; Conduit 17; Gas pipe 18a, 18b; Tube 19; Fin 20; Core bar

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kuriyama 1-2-8 Marunouchi, Chiyoda-ku, Tokyo Incorporated company Kobe Steel, Ltd. Tokyo head office

Claims (2)

[Claims] 1. A check valve is attached to one end of a metal tube coil, and then an inert gas is supplied to the inside from the other end of the metal tube coil so that air in the metal tube coil is passed through the check valve. The metal tube coil is discharged to replace the inside of the metal tube coil with an inert gas atmosphere, then a container containing silicon oil is connected to the other end, and the metal tube coil is heat-treated together with the container. Heat treatment method. 2. The method of claim 1, wherein the silicone oil has a kinematic viscosity of 10 to 5000 centistokes.