JPH04202646A - Heat treating furnace of heat exchanger made of aluminum and production of heat exchanger - Google Patents

Abstract

PURPOSE:To promote age hardening of a fin material and to obtain a heat exchanger high in strength by carrying the core of the heat exchanger to the respective treatment chambers via opening and closing of a partition door by a conveyor line and performing age hardening in a regulation chamber after cooling. CONSTITUTION:The degree of vacuum of a preparatory chamber 25, a degreasing chamber 10, a first preheating chamber 11, a second preheating chamber 12, a vacuum heating chamber 2, a vacuum cooling chamber 3 and a takeout chamber 5 is held at a prescribed degree. The temp. in furnaces of the respective chambers is set at a prescribed value. While successively opening and closing the doors 4a-4h of the respective chambers at every specified time, a carrier 9 is discontinuously moved to the takeout chamber 5 through the respective chambers from the preparatory chamber 25 by a conveyor 8. The vacuum heating furnace 2 is gradually raised in temp. as the carrier is made to the downstream side. Soldering material with which the surface of parts for the core of a heat exchanger is coated is melted. The soldering material is solidified in the vacuum cooling chamber 3 and the intervals of the respective parts are integrally soldered. Then age hardening is promoted in a regulation chamber 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat treatment furnace for promoting brazing and age hardening of an aluminum heat exchanger, and a method for manufacturing the aluminum heat exchanger.

[Prior art and its problems]

An aluminum heat exchanger is assembled by, for example, inserting both ends of a large number of parallel tubes into through holes in a tube plate, and interposing fins between each tube. At this time, at least one of the parts to be joined to each other has its outer surface coated with a brazing material.

Then, both ends of the tube are expanded and the tube ends are crimped into the holes of the tube plate to form a heat exchanger core assembly. A plurality of such cores are housed in a carrier and brazed in a vacuum furnace in which each chamber is connected in series in a tunnel shape, and after the brazing, the cores are taken out to the atmosphere.

[Problem to be solved] Such conventional heat treatment equipment has a brazing chamber with a diameter of 10-3.
Since the heat exchanger core is made of an aluminum alloy and is maintained at a high vacuum of ~10-' Torr, the M of the fin material (0.15 an ~ 0.25 ann) with a particularly thin plate thickness is
A large amount of g and Zn components will scatter into the furnace.

Since these residual components are extremely small, there is a drawback that age hardening due to precipitation of Mg, Si, etc. in the aluminum alloy cannot be expected.

Therefore, there was a drawback that the strength of the brazed heat exchanger core was low.

[Means to solve the problem]

Therefore, the present invention adopts the following configuration in order to eliminate the above-mentioned drawbacks.

The heat treatment furnace of the present invention has a brazing material coated on the surface of the heat exchanger core 1 made of an aluminum alloy.
It has a vacuum heating furnace 2 for melting under a low vacuum of about 1 Torr, and a vacuum cooling chamber 3 and a take-out chamber 5 are successively installed downstream of the vacuum heating furnace 2 through airtight partition doors 4f, 4g, and 4h, respectively. and are placed in series. A heat-retaining adjustment chamber 7 is provided outside the take-out chamber 5 and is maintained at a set temperature via a cooling space 6 open to the atmosphere. A conveyor line 8 connecting the chambers in series is provided.

Further, in the method of the present invention, in the heat treatment furnace, the temperature of the core 1 is maintained at about 200°C in the cooling space 6 opened to the atmosphere while the adjustment chamber 7 is maintained at 150 to 250°C.
When it is cooled to room temperature or above, it is inserted into the adjustment chamber 7 from the cooling space 6 and kept in the adjustment chamber 7 for 20 to 60 minutes.

[For production]

This device uses high-strength aluminum alloy (AI-Zn-Ng).
) or corrosion-resistant aluminum alloy (AI-Ng-Si
) The heat exchanger core formed by the conveyor line 8
is stored in the vacuum heating furnace 2. At this time, the vacuum heating furnace 2 is maintained at a low vacuum to minimize scattering of Mg in the aluminum alloy. And conveyor line 8
Vacuum cooling chamber 3. It is taken out through the take-out chamber 5 into the cooling space 6, where it is cooled down to a certain temperature and immediately stored in the adjustment chamber 7. Then, in the adjustment chamber 7, the core 1 is 150
It is held at a temperature of 250° C. to 250° C. for about 20 minutes to 60 minutes, aged and hardened, and taken out from the adjustment chamber 7.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a schematic plan view of the present apparatus, FIG. 2 shows an example of the set temperature of each chamber in the vacuum furnace, and FIG. 3 shows an example of the degree of vacuum of each chamber in the same furnace.

This heat treatment furnace consists of a vacuum brazing device 26, a cooling space 6, and a temperature control chamber 7. And vacuum brazing device 2
Reference numeral 6 indicates that the vacuum heating furnace 2 is long and narrow, and in this embodiment has a length that can accommodate nine carriers 9, and the maximum carriers 9 are carried into and out of the vacuum heating furnace 2 one by one one by one.

Note that there is no door in the middle of the vacuum heating furnace 2. A second preheating chamber 12 is provided on the upstream side of the vacuum heating furnace 2 via a partition door 4e, and a vacuum cooling chamber 3 is provided on the downstream side via a partition door 4f.

Furthermore, partition doors 4d and 4 are provided on the upstream side of the second preheating chamber 12, respectively.
c, the first preheating chamber 11.c via 4b. Degreasing chamber 10. A preparation room 25 is provided. Furthermore, a take-out chamber 5 is provided on the downstream side of the vacuum cooling chamber 3 via a partition door 4g.

In this embodiment, the degreasing chamber 10 has a length that accommodates six carriers 9, and each chamber except the degreasing chamber 10 and the vacuum heating furnace 2, the preparation chamber 25. First preheating chamber 11. Second preheating chamber 12. Vacuum cooling room 3. The transport length of the take-out chamber 5 is set to a length that can accommodate only one carrier 9.

Further, an external heater 13 is provided in the preparation chamber 25 and the take-out chamber 5, and a reflector and a heater 13 are provided on the inner surface of each chamber except for the vacuum cooling chamber 3. Furthermore, as shown in FIG. 4, a rack and pinion type overhand conveyor is arranged at the upper end of each chamber.

Then, a hanger main body 15 of a predetermined length as shown in FIG.
is moved by the Oharhesodo conveyor.

That is, the rack 23 is provided at the upper end of the hanger body 15,
A sprocket 1 is attached to the bin 22 protruding from the rack 23.
7 meshes. This sprocket 17 is repeatedly rotated and stopped by a motor 24 with a reducer, and the hanger body 15
is moved downstream intermittently. A pair of hooks 20 are suspended from the hanger body 15, and a locking portion of the carrier 9 is removably engaged with the hooks 20. Note that the upper ends of a large number of cores 1 are suspended from the carrier 9. The plane of the core 1 faces the direction of travel, and the side surface faces the side wall of the furnace.

Then, the radiant heat from the heater 13 enters through the gaps between the cores 1, and is absorbed by the core I while being diffusely reflected on the plane of the core I and other surfaces. In this embodiment, the carrier 9 is formed so that its length in the transport direction is shorter than its width direction.

Next, the hanger body 15 is provided with a plurality of rollers 18, which are guided by a rail 21 at the upper end of the vacuum furnace. A plurality of sprockets 17 are arranged at appropriate intervals in the upper part of each chamber, and the hanger main bodies 15 meshed with the sprockets 17 are sequentially conveyed downstream.

Next, a vacuum pump (not shown) is connected to each chamber. An oil rotary pump and a mechanical booster (not shown) are connected to both $ chambers 25 and the degreasing chamber 10,
A degree of vacuum of about 10-' Torr can be maintained. In addition, diffusion pumps are provided in other chambers. A chamber provided with this diffusion pump can maintain a higher degree of vacuum of about 10-' to 10-6 Torr. Further, dry air is connected to the preparation chamber and the extraction chamber, and a vibrate line for introducing nitrogen gas is connected to the degreasing chamber, heating chamber, and cooling chamber through valves.

Next, the set temperature of each chamber is maintained as shown in FIG. 2, for example. Note that this set temperature is changed as appropriate depending on the size of the heat exchanger and other factors. For example, the temperature of the preparation room 25 and the extraction room 5 is about 100°C to 200°C, and the temperature of the degreasing room 10 is about 30°C.
00°C to 450°C, the first preheating chamber 11. The second preheating chamber 12 is heated to 350°C to 500°C, and the vacuum heating furnace 2 is heated to 45°C.
It is set at 0°C to 650'C.

The heater of the vacuum heating furnace 2 is divided into a plurality of heaters from the upstream side to the downstream side, and the set temperature of each heater increases in an upward step-like manner toward the downstream side, and increases in a slightly downward step-like manner at the end. It is set so that it becomes lower in sequence.

Next, a fan 16 and a cooling space 6 are provided outside the extraction chamber 5.
is provided, and a traverse 14 is arranged there.

This traverse 14 is a conveyor that connects the downstream end of the vacuum brazing device 26 and the upstream end of the adjustment chamber 7.

Next, the adjustment chamber 7 has partition doors 4i and 4 at both ends in the longitudinal direction.
j is provided and is elongated.

A large number of carriers 9 can be stored in the adjustment chamber 7, and the takt time, ie, cycle time, of the carriers 9 stored therein or taken out from the adjustment chamber 7 matches that of the vacuum brazing device 26. Then, the time during which each core 1 is stored in the adjustment chamber 7 is 20 minutes to 6 minutes.
The length is set to approximately 0 minutes. A heater 13 is provided inside the adjustment chamber 7, and the temperature inside the adjustment chamber 7 is 150°C to 2°C.
The temperature is maintained at 50°C. At the same time, an overhand conditioner as shown in FIG. 4 is also provided in the adjustment chamber 7.

In addition, an exhaust heat recovery device 27 is provided downstream of the cooling space 6 as shown in FIG. 6, and the heat generated when cooling the carrier 9 and the core 1 in the cooling space 6 is recovered and transferred to the adjustment chamber. It can also be reused as part of the heat source.

Next, we will discuss how to use this heat treatment furnace. First, preparation room 2
5. Degreasing chamber 10. While maintaining the unloading chamber 5 at a low vacuum of about 10-' Torr, the degreasing chamber 10. First preheating chamber 11
．． Second preheating chamber 12. Vacuum heating furnace 2. The vacuum cooling chambers 3 are each maintained at a degree of vacuum of about 10-3 Torr to 10-' Torr. Furthermore, the temperature inside the furnace in each chamber is set as shown in FIG. 2, as an example. After completing such f$ preparation, a small amount of dry air or nitrogen gas is supplied into the vacuum heating furnace 2 to maintain the inside at a low vacuum of about 10-'Torr.

Therefore, while sequentially opening and closing each field 48 to 4h at regular intervals, the carrier 9 is moved from the preparation chamber 25 to the degreasing chamber 10° to the first preheating chamber 11. Second preheating chamber 12. Vacuum heating furnace 2゜Vacuum cooling chamber 3
．． It is sequentially and intermittently moved to the take-out chamber 5. Note that when storing the carrier 9 in the preparation room 25, the preparation room 2
Supply dry air to 5 to create double pressure inside. Further, the leak valve is opened for a certain period of time to equalize the atmospheric pressure and the pressure inside the furnace, and then the partition door 4a is opened, and the carrier 9 is stored in the preparation chamber 25 by the oat λ-head conveyor. Then, the partition door 4a is closed, the oil rotary vacuum pump and the mechanical booster are operated in order, and the interior is
-1 to 10- Set the pressure to about 100 Torr.

Next, the partition door 4 at the boundary between the preparation room 25 and the degreasing room 10
b is opened, the carrier 9 is stored in the degreasing chamber 10, and the partition door 4b is closed. Within the degreasing chamber 10, the carrier 9 is transported downstream at low speed. Carriers are sequentially carried into this degreasing chamber 10 and stored in a total of holes. And degreasing room 1
Each core 1 is heated in 0 to evaporate the oil on the surface of the core 1.

Next, the carrier 9 that has reached the tip of the degreasing chamber 10 is stored in the first preheating chamber 11 after the partition door 4c is opened, and the partition door 4c is closed.

Next, the carrier 9 is moved from the first preheating chamber 11 to the second preheating chamber 2 and from the second preheating chamber 12 to the vacuum heating furnace 2 at regular intervals. In the vacuum heating furnace 2, the carrier 9 is conveyed downstream at low speed similarly to the degreasing chamber IO.

The temperature of the vacuum heating furnace 2 gradually rises as it goes downstream, and the brazing material coated on the surface of the heat exchanger core parts melts.

Next, the carrier 9 that has reached the tip inside the vacuum heating furnace 2 is stored in the vacuum cooling chamber 3, where the molten brazing filler metal solidifies and the parts are integrally brazed, and the aluminum is heated by rapid cooling. It is possible to perform aging treatment after hardening the exchanger.

Furthermore, the carrier 9 passes through the take-out chamber 5 and the traverse 1
4, it is taken out to the outside. Then, the core 1 is further cooled by the fan 16, and when the temperature of the core 1 drops to 250° C. or less, the core 1 is stored in the adjustment chamber 7. In addition, 250
If held at a temperature above 0.degree. C. for a long time, it will harden in a very short time, but it has the disadvantage that it will soften again after hardening. The cycle time stored in the adjustment chamber 7 is the same as the cycle time taken out from the extraction chamber 5.

In addition, only one carrier 9 is stored in the traverse,
The product is stored from the unloading chamber to the adjustment chamber within one takt time.

The core l stored in the adjustment chamber 7 is transported inside at low speed or intermittently moved downstream, and is taken out from the carrier 9 that has reached the downstream end of the adjustment chamber 7 to the outside. The inside of the adjustment chamber 7 is maintained at about 150°C to 250°C by the heater 13, but the most preferable temperature is about 200°C. Also, the time that the core l is stored in the adjustment chamber 7 is 20
The time is about 60 minutes, preferably about 30 minutes.

Note that these values vary somewhat depending on the amount of remaining alloy components and the cooling rate. Age hardening is rapidly promoted within this conditioning chamber 7, increasing the strength of the core.

〔Effect of the invention〕

(1) In the heat treatment furnace of the present invention, the core 1 to be brazed under low vacuum is in the vacuum heating furnace 2. Vacuum cooling room 3. After passing through the extraction chamber 5, it is rapidly cooled in the cooling space 6, and then kept at a constant temperature in the adjustment chamber 7, which promotes age hardening of the aluminum heat exchanger, especially the fin material, and improves its strength. can provide a high heat exchanger.

According to experiments, the hardness of the fin according to the present invention was twice that of the conventional fin. That is, 43003 (AI-Mn aluminum alloy) is used as the fin material of a typical aluminum heat exchanger, and its Vickers hardness is about 35. On the other hand, the weight ratio is 1.0%Mn-0.9%
When an aluminum alloy containing 54-0.4% Mg-1,5Zn and the balance A was treated in the heat treatment furnace of the present invention, the Pinkers hardness was approximately 70. In this furnace, the alloy composition of the fin material after brazing is 0.3% Mg, 0.4%
Zn remained and the Vickers hardness after brazing was about 50, and it was heated at 200°C for 30 minutes to obtain the aforementioned Vickers hardness of 70.

As the hardness increases in this manner, the tensile strength of the heat exchanger core increases in proportion to the hardness. Therefore, by using this heat treatment furnace, it is possible to use a fin material that is thinner than the thickness of conventional fin materials, and it is possible to simultaneously reduce the weight of the heat exchanger and improve heat conductivity.

(2) Also, according to the manufacturing method of the present invention, after the core l has been cooled down to a predetermined temperature or lower in the cooling space 6, it is inserted into the regulating chamber 7 and kept at a constant temperature. The thermal efficiency of No. 7 is improved, and as a result, the manufacturing cost of the aluminum heat exchanger can be reduced. At the same time, a heat exchanger with high strength can be rapidly produced.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of the heat treatment furnace, FIG. 2 shows an example of the set temperature of each chamber in the vacuum furnace, and FIG. 3 shows an example of the degree of vacuum in each chamber of the vacuum furnace. FIG. 4 shows an example of an in-furnace conditioner, FIG. 5 is a side view of the hanger, and FIG. 6 shows another embodiment of the adjustment chamber of the heat treatment furnace. 1...Core 2...Vacuum heating furnace 3...
Vacuum cooling room 4a-4j...Partition door 5...Take-out room 6...Cooling space 7...314 room
8...Conveyor line 9...Carrier
10... Degreasing chamber 11... First preheating chamber 12
...Second preheating chamber 13...Heater 14.
...Traverse 15...Hanger body 16...
Fan 17...Sprocket 18...Roller 1
9...Furnace 20...Hook 21...
Rail 22...Pin 23...Rack
24...Motor 25...Preparation room 2
6... Vacuum brazing device 27... Exhaust heat recovery device Representative Patent attorney Kubo 1) Takumi Figure 5 Figure 4

Claims (4)

[Claims] (1) A vacuum heating furnace 2 for melting the brazing filler metal coated on the surface of the heat exchanger core 1 made of aluminum alloy under low vacuum, and an airtight partition door 4f located downstream of the vacuum heating furnace 2. It has a vacuum cooling chamber 3 and a take-out chamber 5 which are arranged in series through 4g and 4h, and the inside is maintained at a set temperature through a cooling space 6 which is open to the atmosphere outside the take-out chamber 5. 1. A heat treatment furnace for an aluminum heat exchanger, characterized in that a temperature adjustment chamber 7 for maintaining temperature is provided, and a conveyor line 8 is provided to connect the respective chambers in series. (2) a vacuum heating furnace 2 for melting the brazing filler metal coated on the surface of the heat exchanger core 1 made of aluminum alloy under low vacuum; and airtight partition doors 4f downstream of the vacuum heating furnace 2; It has a vacuum cooling chamber 3 and a take-out chamber 5 which are arranged in series through 4g and 4h, and the inside is maintained at a set temperature through a cooling space 6 which is open to the atmosphere outside the take-out chamber 5. A temperature control chamber 7 is provided for maintaining heat at a temperature of 150 to 250° C., and a conveyor line 8 is provided to connect the respective chambers in series. The temperature of the core 1 in the cooling space 6 is approximately 200℃.
When it is cooled from below to room temperature, it is inserted into the conditioning chamber 7 from the cooling space 6 and kept in the conditioning chamber 7 for 20 to 60 minutes.
A method of manufacturing an aluminum heat exchanger configured to retain a temperature of 100%. (3) In claim 1 or 2, the fin material of the heat exchanger core 1 is an Al-Mg-Zn alloy or an Al-Mg
- Made of aluminum alloy based on Si alloy or Al-Mg-Zn-Si alloy. (4) According to claim 2 or 3, the time from the take-out chamber 5 to the adjustment chamber 7 is within one takt time.