JP3277218B2 - Heat treatment furnace for aluminum heat exchanger and method for manufacturing the heat exchanger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat treatment furnace for promoting brazing and age hardening of an aluminum heat exchanger, and a method of manufacturing the aluminum heat exchanger.

[Prior art and its problems]

As an example, an aluminum heat exchanger is assembled by inserting both ends of a large number of tubes arranged in parallel into through holes of a tube plate and interposing fins between the tubes. At least one of the parts to be joined at this time has an outer surface coated with a brazing material. Then, both ends of the tube are expanded, and the tube end is pressed into the hole of the tube plate to form a heat exchanger core assembly. Such a core is stored in multiple carriers,
Brazing is performed in a vacuum furnace in which the chambers are connected in series in a tunnel shape, and after brazing, the chamber is taken out to the atmosphere.

[Problem to be solved]

Such a conventional heat treatment apparatus has a brazing chamber of 10 ^-3 to
Since the vacuum is maintained at a high vacuum of about 10 ⁵ Torr, Mg and Zn components in the fin material (0.15 mm to 0.25 mm) with a particularly low plate pressure among the heat exchanger cores made of aluminum alloy scatter a lot in the furnace. Resulting in.

Since these residual components are extremely small, there is a disadvantage that age hardening accompanying precipitation of Mg ₂ Si or the like in the aluminum alloy cannot be expected.

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

[Means for solving the problem]

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

The heat treatment furnace of the present invention is capable of reducing the brazing material coated on the surface of the heat exchanger core 1 made of an aluminum alloy by 0.01 to 1T.
It has a vacuum heating furnace 2 for melting under a low vacuum of about orr, and airtight partition doors 4f, 4g,
The vacuum cooling chamber 3 and the extraction chamber 5 are sequentially arranged in series via 4h. Further, outside the unloading chamber 5, there is provided an adjusting chamber 7 for keeping the inside at a set temperature via a cooling space 6 opened to the atmosphere. And the conveyor line 8 which connects each room in series was provided.

Further, the method of the present invention is characterized in that in the heat treatment furnace, the temperature of the core 1 is about 200 ° C. or less and the temperature of the core 1 is not more than 200 ° C. When cooled as described above, it is inserted into the adjustment chamber 7 from the cooling space 6 and is held in the adjustment chamber 7 for 20 to 60 minutes.

[Action]

In this apparatus, a heat exchanger core made of a high-strength aluminum alloy (Al-Zn-Ng) or a corrosion-resistant aluminum alloy (Al-Ng-Si) is housed in a vacuum heating furnace 2 by a conveyor line 8. At this time, the vacuum heating furnace 2 is maintained at a low vacuum, and scattering of Mg in the aluminum alloy is reduced as much as possible. And, by the conveyor line 8, the vacuum cooling chamber 3,
It is taken out to the cooling space 6 through the take-out chamber 5, where it is cooled to a certain temperature and immediately stored in the adjustment chamber 7. Then, the core 1 is held at 150 ° C. to 250 ° C. for about 20 minutes to 60 minutes in the adjustment chamber 7, is age-hardened, and is taken out of the adjustment chamber 7.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

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

This heat treatment furnace includes a vacuum brazing device 26, a cooling space 6, and a temperature control chamber 7. And the vacuum brazing device 26
The vacuum heating furnace 2 is formed to be elongated, and in this embodiment, the length is such that nine carriers 9 can be stored.
A maximum of seven carriers 9 are sequentially carried in and out one by one.

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

Also, on the upstream side of the second preheating chamber 12, partition doors 4d, 4c, 4b are respectively provided.
A first preheating chamber 11, a degreasing chamber 10, and a preparation chamber 25 are provided via the first preheating chamber 11, the debinding chamber 10, and the preparation chamber 25. Further, an extraction chamber 5 is provided downstream of the vacuum cooling chamber 3 through a partition door 4g.

In this embodiment, the degreasing chamber 10 has a length in which six carriers 9 are accommodated. Except for the degreasing chamber 10 and the vacuum heating furnace 2, each chamber, namely, the preparation chamber 25, the first preparatory chamber 11, the second preheating The transport length of the chamber 12, the vacuum cooling chamber 3, and the take-out chamber 5 is set to a length that can accommodate only one carrier 9.

An externally heated heater 13 is provided in the preparation chamber 25 and the take-out chamber 5, and each chamber other than the vacuum cooling chamber 3 is provided with a reflector and a heater 13 on its inner surface. I have. Further, as shown in FIG. 4, a rack-and-pinion type overhead conveyor is arranged at the upper end of each chamber. Then, the hanger body 15 having a predetermined length as shown in FIG. 5 is moved by the overhead conveyor.

That is, the rack 23 is provided at the upper end of the hanger body 15, and the sprocket 17 meshes with the pin 22 protruding from the rack 23. The sprocket 17 is rotated and stopped repeatedly by a motor 24 equipped with a speed reducer, and moves the hanger body 15 intermittently to the downstream side. A pair of hooks 20 hang down from the hanger main body 15, and the locking portions of the carrier 9 engage with the hooks 20 in a detachable manner. The upper ends of a number of cores 1 are suspended from the carrier 9. Then, the plane of the core 1 faces the traveling direction, and the side faces face the side walls of the furnace. The radiant heat from the heater 13 enters through the gap between the cores 1 and is absorbed by the cores 1 while irregularly reflecting the plane and the like of the cores 1. In this embodiment, the length of the carrier 9 in the transport direction is shorter than the length in the width direction.

Next, the hanger body 15 is provided with a plurality of rollers 18,
It is guided to the 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 body 15 meshing with the sprockets 17 is transported forward and downstream.

Next, each chamber is connected to a vacuum pump (not shown). An oil rotary pump and a mechanical booster (not shown) are connected to the preparation chamber 25 and the degreasing chamber 10, and 10 ^-1
It can be maintained at a vacuum of about Torr. The other chambers are additionally provided with a diffusion pump. The chamber provided with the diffusion pump can maintain a higher degree of vacuum of about 10 ^-3 to 10 ^-6 Torr. Dry air is supplied to the preparation room and the extraction room,
A pipeline for introducing nitrogen gas is connected to the heating chamber and the cooling chamber via a valve.

Next, the set temperature of each chamber is maintained as shown in FIG. 2 as an example. This set temperature is appropriately changed depending on the size of the heat exchanger and the like. For example, the preparation room 25 and the take-out room 5 are at about 100 ° C. to 200 ° C., and the degreasing room 10 is at 300 ° C. to 450 ° C.
The temperature of the first preheating chamber 11 and the second preheating chamber 12 is set at 350 ° C. to 500 ° C., and the temperature of the vacuum heating furnace 2 is set at 450 ° 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 rises stepwise toward the downstream side, and slightly descends stepwise at the end thereof. Are set so as to be sequentially lower.

Next, the fan 16 and the cooling space 6 are located outside the take-out chamber 5.
Is provided, and the traverse 14 is arranged there. The traverse 14 is a conveyor connecting the downstream end of the vacuum brazing device 26 and the upstream end of the adjustment chamber 7.

Next, the adjusting chamber 7 has partition doors 4i, 4j at both ends in the longitudinal direction.
Are provided and are elongated. A large number of carriers 9 can be stored in the adjustment chamber 7 and the carriers 9 stored therein or taken out of the adjustment chamber 7
The cycle time corresponds to that of the vacuum brazing apparatus 26. The length is set such that the time for each core 1 to be stored in the adjustment chamber 7 is about 20 to 60 minutes. A heater 13 is provided inside the adjustment chamber 7, and maintains the inside at 150 ° C to 250 ° C. At the same time, an overhead conveyor as shown in FIG.

An exhaust heat recovery device 27 is provided downstream of the cooling space 6, as shown in FIG. 6, to recover the heat generated when the carrier 9 and the core 1 are cooled in the cooling space 6, and to transfer the heat to the conditioning room. 7 can be reused as a part of the heat source.

Next, a method of using the present heat treatment furnace will be described. First preparation room
The degreasing chamber 10, the first preheating chamber 11, the second preheating chamber 12, the vacuum heating furnace 2, and the vacuum cooling chamber 3 are maintained at 25, the degreasing chamber 10, and the discharge chamber 5 at a low vacuum of about 10 ^-1 Torr. Each is maintained at a vacuum degree of about 10 ⁻³ Torr to 10 ⁻⁵ Torr. Further, the furnace temperature of each chamber is set as an example as shown in FIG. After the completion of such preparation, dry air or nitrogen gas is slightly supplied into the vacuum heating furnace 2 to maintain the inside at a low vacuum of about 10 ^-1 Torr.

Therefore, the carrier 9 is moved from the preparation chamber 25 to the degreasing chamber 10, the first preheating chamber 11,
The second preheating chamber 12, the vacuum heating furnace 2, the vacuum cooling chamber 3, and the discharge chamber 5 are sequentially and intermittently moved. When the carrier 9 is stored in the preparation room 25, dry air is supplied to the preparation room 25 in advance to double-press the inside. Then, the leak valve is further opened for a certain period of time, the atmospheric pressure and the pressure in the furnace are made equal, and then the partition door 4a is opened, and the carrier 9 is stored in the preparation room 25 by an overhead conveyor. And the partition door 4a
Is closed, and the oil rotary vacuum pump and the mechanical booster are sequentially operated, and the pressure inside is set to about 10 ^-1 to 10 ^-2 Torr.

Next, the partition door 4b at the boundary between the preparation chamber 25 and the degreasing chamber 10 is opened, the carrier 9 is stored in the degreasing chamber 10, and the partition door 4b is closed. In the degreasing chamber 10, the carrier 9 is transported at a low speed to the downstream side. Carriers are sequentially loaded into the degreasing chamber 10, and a total of six carriers are stored. Then, each core 1 is heated in the degreasing chamber 10 to evaporate oil on the surface of the core 1.

Next, the carrier 9 that has reached the leading end 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 moves from the first preheating chamber 11 to the second preheating chamber 12 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 to the downstream side at a low speed similarly to the degreasing chamber 10.

The temperature of the vacuum heating furnace gradually increases toward the downstream side, and the brazing material coated on the surface of the component of the heat exchanger core melts.

Next, the carrier 9 which has reached the tip in the vacuum heating furnace 2 is accommodated in the vacuum cooling chamber 3, where the molten brazing material is solidified and the parts are integrally brazed. Aging treatment after quenching the exchanger becomes possible.

Further, the carrier 9 passes through the extraction chamber 5 and traverses
It is taken out by 14. Then, when the core 1 is further cooled by the fan 16 and the temperature of the core 1 falls to 250 ° C. or less, the core 1 is stored in the adjustment chamber 7. If the temperature is kept at 250 ° C. or higher for a long time, the composition is cured in an extremely short time, but has a disadvantage that it is softened again after the curing. The cycle time stored in the adjustment chamber 7 is the same as the cycle time taken out of the take-out chamber 5.

Further, only one carrier 9 is stored in the traverse, and is stored from the unloading chamber to the adjustment chamber within one tact time. The core 1 accommodated in the adjustment chamber 7 is conveyed at a low speed or moves intermittently downstream, and is taken out from the carrier 9 that has reached the downstream end of the adjustment chamber 7. The inside of the adjustment chamber 7 is maintained at about 150 ° C. to 250 ° C. by the heater 13, and the most preferable temperature is about 200 ° C. or,
The time in which the core 1 is stored in the adjustment chamber 7 is about 20 minutes to 60 minutes, and preferably about 30 minutes. Note that these numerical values slightly vary depending on the residual amount of the alloy component and the cooling rate.
Then, age hardening is rapidly promoted in the adjustment chamber 7,
The strength of the core increases.

〔The invention's effect〕

(1) In the heat treatment furnace of the present invention, the core 1 to be brazed under a low vacuum is rapidly cooled in the cooling space 6 after passing through the vacuum heating furnace 2, the vacuum cooling chamber 3, and the extraction chamber 5, and then adjusted. Since the temperature is maintained at a constant temperature by the chamber 7, the age hardening of the aluminum heat exchanger, particularly the fin material, is promoted, and a high strength heat exchanger can be provided.

According to experiments, the hardness of the fin according to the present invention was twice as high as that of the conventional fin. That is, A3003 (Al-Mn-based aluminum alloy) is used as a fin material of a normal aluminum heat exchanger, and its Vickers hardness is about 35.
On the other hand, 1.0% Mn-0.9% Si-0.4% Mg-
When the aluminum alloy of 1.5Zn and the remaining Al was treated in the heat treatment furnace of the present invention, the Vickers hardness became about 70. The alloy component of the fin material after brazing in this furnace is
0.3% Mg and 0.4% Zn remained, and the Vickers hardness after brazing was about 50. The Vickers hardness was heated at 200 ° C. for 30 minutes to obtain the aforementioned Vickers hardness of 70.

As the hardness increases, the tensile strength of the heat exchanger core increases in proportion to the hardness. Therefore, when the present heat treatment furnace is used, a fin material thinner than the conventional fin material can be used, and the weight reduction of the heat exchanger and the improvement of heat transfer can be achieved at the same time.

(2) According to the manufacturing method of the present invention, after the core 1 is cooled to a predetermined temperature or lower in the cooling space 6, it is inserted into the adjustment chamber 7 and maintained at a constant temperature. The thermal efficiency is improved, and as a result, the manufacturing cost of the aluminum heat exchanger can be reduced. At the same time, a high-strength heat exchanger can be rapidly produced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of the present heat treatment furnace, FIG. 2 shows an example of a set temperature of each chamber in a vacuum furnace, and FIG. 3 shows an example of a degree of vacuum in each chamber of the vacuum furnace. FIG. 4 shows an example of the in-furnace conveyor, FIG. 5 shows a side view of the hanger, and FIG. 6 shows another embodiment of the conditioning chamber of the present heat treatment furnace. DESCRIPTION OF SYMBOLS 1 ... Core, 2 ... Vacuum heating furnace 3 ... Vacuum cooling room, 4a-4j ... Partition door 5 ... Extraction room, 6 ... Cooling space 7 ... Adjustment room, 8 ... Conveyor line 9 ...... Carrier, 10 degreaser 11 ...... first preheating chamber 12, 12 ... second preheating chamber 13 ... heater 14, traverse 15 ...... hanger body 16, fan 17 sprocket 18, Roller 19 Furnace 20 Hook 21 Rail 22 Pin 23 Rack 24 Motor 25 Preparatory room 26 Vacuum brazing device 27 Exhaust heat recovery device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-197874 (JP, A) JP-A-57-62859 (JP, A) JP-A-54-114455 (JP, A) 177952 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F27B 9/00-9/40 B23K 1/00 330 C22F 1/04

Claims (4)

(57) [Claims] 1. A vacuum heating furnace 2 for melting a brazing material coated on the surface of a component of a heat exchanger core 1 made of an aluminum alloy under a low vacuum, and an airtight partition door downstream of the vacuum heating furnace 2. It has a vacuum cooling chamber 3 and a take-out chamber 5 arranged in series through 4f, 4g, 4h in sequence, and the inside is provided through a cooling space 6 open to the outside of the take-out chamber 5 and open to the atmosphere. A heat treatment furnace for an aluminum heat exchanger, comprising: a regulating chamber 7 for keeping heat at a set temperature; and a conveyor line 8 for connecting the chambers in series. 2. The fin material of the heat exchanger core 1 according to claim 1, wherein the fin material is based on an Al-Mg-Zn alloy, an Al-Mg-Si alloy, or an Al-Mg-Zn-Si alloy. Heat treatment furnace for aluminum heat exchanger for aluminum alloys. 3. A vacuum heating furnace 2 for melting a brazing material coated on the surface of a component of a heat exchanger core 1 made of an aluminum alloy under a low vacuum, and a sealing door downstream of the vacuum heating furnace 2 in an airtight manner. It has a vacuum cooling chamber 3 and a take-out chamber 5 arranged in series through 4f, 4g, 4h in sequence, and the inside is provided through a cooling space 6 open to the outside of the take-out chamber 5 and open to the atmosphere. A regulating chamber 7 for keeping the temperature maintained at a set temperature is provided, and a conveyor line 8 connecting the respective chambers in series is provided. When the temperature of the core 1 is cooled to about 200 ° C. or less and room temperature or higher in the open cooling space 6, it is inserted into the adjusting chamber 7 from the cooling space 6 and is controlled for 20 minutes to 60 minutes. A method for manufacturing an aluminum heat exchanger that is configured to be held for a while. 4. A method for manufacturing an aluminum heat exchanger according to claim 3, wherein the time of storage from said extraction chamber 5 to said adjustment chamber 7 is within one tact time.