JP2658799B2 - Aluminum vacuum brazing furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum vacuum brazing furnace, and more particularly, to vacuum brazing between aluminum members as components of an aluminum heat exchanger such as a radiator for a vehicle, an evaporator for a vehicle air conditioner, and a condenser. Aluminum vacuum brazing furnace.

[0002]

2. Description of the Related Art In general, an aluminum vacuum brazing furnace of this type transports an aluminum member, which is a combination of a brazing material containing magnesium, into a brazing chamber, and sets the brazing chamber to a vacuum atmosphere. (See, for example, JP-A-63-52764). Here, the reason why the magnesium-containing brazing material is used is that, at the time of brazing, the aluminum oxide film is destroyed and brazing can be performed well.

[0003]

However, in a conventional aluminum vacuum brazing furnace, after brazing, the brazed article to be brazed is carried out of the brazing chamber and then to be brazed. When the brazing chamber is opened to the atmosphere when it is carried into the brazing chamber, the evaporated magnesium in the brazing chamber is oxidized into powdered magnesium oxide, and this magnesium oxide accumulates on the floor in the brazing chamber. I do.

[0004] The magnesium oxide deposits are scattered to an evacuation system during vacuum evacuation in the next cycle of brazing, causing malfunctions and performance degradation of pumps for evacuation.
This causes clogging of the filter. Further, in order to prevent such a problem, manual cleaning work for removing magnesium oxide deposits must be frequently performed. Also, the brazing chamber contains magnesium oxide that has not yet been oxidized, and the impact energy when oxidized magnesium is usually oxidized is very dangerous. There was also the problem of having to do it.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and actively oxidizes magnesium evaporate and automatically recovers magnesium oxide. It is an object of the present invention to prevent performance degradation, filter clogging, and the like, eliminate complicated cleaning work, and safely remove evaporated magnesium.

[0006]

In order to solve the above-mentioned problems, an aluminum vacuum brazing furnace according to the present invention carries an aluminum member combined with a brazing material containing magnesium into a brazing chamber, and carries out the brazing. An aluminum vacuum brazing furnace for brazing the aluminum member by heating the chamber to a vacuum atmosphere and raising the temperature to a temperature equal to or higher than the melting point of the brazing material, comprising a magnesium recovery device, After the end, air is introduced into the brazing chamber, and the atmosphere opening means for oxidizing magnesium evaporated from the brazing material during brazing, and is installed below the brazing chamber to receive the magnesium oxide generated by opening to the atmosphere. Receiving means, installed downstream of the receiving means,
Separating and collecting means for separating and collecting the magnesium oxide received by the receiving means.

[0007]

The air opening means opens the brazing chamber to the atmosphere with dry air at -40 ° C. after the brazing is completed.
When this atmosphere is released, the evaporated magnesium evaporated from the brazing material during brazing is oxidized to magnesium oxide. The magnesium oxide is received by the receiving means and separated and collected by the separating and collecting means.

Thus, according to the present invention, after brazing, the evaporated magnesium is positively oxidized into magnesium oxide, and the magnesium oxide is automatically recovered. Therefore, it is possible to prevent malfunction of the pumps of the vacuum exhaust system, performance degradation, filter clogging, and the like, abolish complicated cleaning work, and safely remove evaporated magnesium.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

[0010] An aluminum vacuum brazing furnace according to one embodiment comprises a furnace body and a magnesium recovery device.
2 and FIG. 2 schematically show a furnace main part, and FIG.
Schematically shows the main part of the magnesium recovery apparatus.

1 and 2, reference numeral 1 denotes a furnace body formed in a substantially cylindrical shape in a horizontal direction. An exhaust port 2 of a vacuum evacuation system is provided in the furnace body 1 so as to communicate with a space in the furnace body. The exhaust port 2 includes a switching valve 60, a diffusion pump 61, and a mechanical booster pump 62, which are components of a vacuum exhaust system.
And the rotary pump 63 in order. A rail 3 projects from the upper part of the furnace body 1, and a heater module forming a brazing chamber 4 is suspended from the rail 3. A carrier rail 5 is suspended from the ceiling of the brazing chamber 4, and a carrier 7 on which a product to be brazed (an aluminum member obtained by combining a brazing material containing magnesium) 6 is vertically mounted. Are suspended in multiple stages. The carrier 7 is movable in a direction perpendicular to the plane of FIG.

In this embodiment, two brazing chambers 4 are formed independently in the left-right direction in FIG. Except for the ceiling and bottom surface of each brazing chamber 4, on the inner surface of the side wall 8, a pair of a heat reflecting plate 9 and a heater 10 as heater means are provided corresponding to the position of the brazed article 6. Pairs are installed close to each other. And part 8a of the wall 8 of the brazing chamber 4
As shown in FIG. 7, the structure is such that it can be opened and closed by a driving means 30 (not limited to a rotating operation as shown in FIG. 7) composed of an air cylinder 11 and the like.
The heat reflection plate 9 and the heater 10 are also provided as a pair on the inner surface of the device. Therefore, a part of the brazing chamber 4 can be opened and closed by the movable wall (movable door with heater) 12 as described above. In the case of the present embodiment, the movable wall 12 is located at a position close to the front door 22 and the rear door 23 in each brazing chamber 4, as shown in FIG. Individually formed. Further, the heat reflection plate 9 and the heater 10 are also provided on the inner surfaces of the front door 22 operated when loading and unloading the article 6 to be brazed into and out of the brazing chamber 4 and the rear door 23 operated during maintenance and inspection. They are installed as a pair.

Driving means 30 for driving the movable wall 12
Is configured as follows.

A rotating shaft 31 is vertically fixed to an end of the movable wall 12 on the front door 22 side or the rear door 23 side. The rotating shaft 31 is connected to the connecting member 3 above the ceiling 4 a of the brazing chamber 4.
2 is connected to the rod 11a of the air cylinder 11 through the movable wall 1 when the rod 11a is at the rear end position.
2 is in the closed position, the movable wall 12 is in the open position when the rod 11a is at the front end position, and the rotating shaft 31 is rotated in the direction of the arrow a when the rod 11a is advanced from the rear end position to move the movable wall 12 Is opened from the closed position, and when the rod 11a retreats from the front end position, the rotating shaft 31 is rotated in the direction of arrow b to close the movable wall 12 from the open position.
The above-described operation of the air cylinder 11 is realized by supplying / exhausting air to / from each of the head-side chamber 11b and the rod-side chamber 11c in the air cylinder 11 according to a control procedure described later.

Next, the air cylinder control means 33 will be described.

The air cylinder control means 33 has air hoses 34 and 35 communicating with the head side chamber 11b and the rod side chamber 11c of the air cylinder 11. Rod side chamber 11c
Is connected to a port A of a 4-port 2-position switching solenoid valve 36, and an air hose 35 communicating with the head side chamber 11b is connected to a port B of the solenoid valve 36. The air supply port P of the solenoid valve 36 has, for example, 4 kg / cm
An air source 37 for generating compressed air of the ^{second type} is connected.

The solenoid valve 36 is driven by a valve drive circuit 38. The valve drive circuit 38 checks a signal from an open position detection switch 39 that is turned on when the rod 11a is at the front end position to check the open position of the movable wall 12 and a closed position of the movable wall 12. The signal from the switch 40 for detecting the closed position, which is turned on when the rod 11a is at the rear end position, and the front door 22 is moved to the closed position to confirm that the front door 22 has been changed from the open position to the closed position. A signal from the front door closing position detection switch 41 that is turned on when the temperature of the brazed article 6 in the brazing chamber 4 is detected,
A signal from the temperature sensor 42 that outputs a signal having a voltage value proportional to the temperature is input. The power supply to the two electromagnetic solenoids 43 and 44 of the solenoid valve 36 is controlled based on these input signals. Here, one electromagnetic solenoid 43 is connected to the movable wall 12.
Is a closing solenoid that is energized when rotating or maintaining the movable wall in the closed position, and the other electromagnetic solenoid 44 is
Is an opening solenoid that is energized when turning or maintaining the open position.

When the movable wall 12 is at the closed position, the valve drive circuit 38 turns on the closing solenoid 43. At this time, the rod 11a is at the rear end position, and the switch 40 for detecting the closed position is in the ON state. When the movable wall 12 is in the closed position, the front door 2 is used to start brazing.
2 is closed, the front door closed position detection switch 41 is turned on. When the front door closed position detection switch 41 is turned on, the opening solenoid 44 is energized, and the closing solenoid 43 is de-energized. To For this reason, the spool of the solenoid valve 36 is switched, the head side chamber 11b of the air cylinder 11 is supplied with air, the rod side chamber 11c is exhausted, the rod 11a moves forward, and the movable wall 12 is opened. By the opening operation of the movable wall 12, the switch 40 for detecting the closed position is turned off, and the switch 39 for detecting the open position is turned on. afterwards,
When the temperature of the brazed article 6 in the brazing chamber 4 rises and reaches near the magnesium evaporation temperature (for example, 545 ° C.),
Since the output voltage of the temperature sensor 42 becomes higher than the reference voltage,
The closing solenoid 43 is energized, and the opening solenoid 4 is turned on.
4 is de-energized. Therefore, the spool of the solenoid valve 36 returns to the original position, the rod side chamber 11c of the air cylinder 11 is supplied with air, the head side chamber 11b is exhausted, the rod 11a is retracted, and the movable wall 12 is closed.

The article 6 to be brazed is an aluminum heat exchanger such as a radiator for a car, an evaporator for a car air conditioner, and a condenser. The brazing material for the brazing is a composition as shown in Table 1 below. According to the present embodiment, the content of magnesium is reduced from 1.2% to 0.6% in the related art.

[0020] Each heater 10 is configured as shown in FIGS. 5 and 6, reference numeral 13 denotes a box made of stainless steel or the like. Inside the box 13, a plurality of heater support rods 14 supported by the box 13 are provided.
The electric heater 15 is wound. This electric heater 15
Is made of an electric heater material such as Kanthal wire. Both ends of the electric heater 15 are connected to the electrodes 16 respectively.
Each of the electrodes 16 includes an electrode rod 17 having one end to which an end 15 a of an electric heater 15 is fixed, an insulator 18 disposed on the outer periphery of the electrode rod 17, and a bolt 19 fixed to the other end of the electrode rod 17. And a terminal 20 fixed to the other end of the electrode rod 17 by the bolt 19 and to which the tip of the heater cable 27 is fixed. On the floor of the box 13, one or a plurality of heat reflection plates 21 for preventing heat radiation are disposed. The heat reflecting plate 21 is made of a material such as stainless steel.

As shown in FIG. 6, the heater 10 constructed as described above has one or a plurality of heat reflecting plates 9 interposed on the inner surface side of the frame constituting the wall 8 of the brazing chamber 4. It is mounted on top. In addition, the heater 10 includes the front door 2
2 and the inner surfaces of the rear door 23 are also attached in the same manner as described above.

A heat reflection plate 24 is also provided on the ceiling of the brazing chamber 4.

1 and 2, in the ceiling of the brazing chamber 4, dry air, for example, -40 ° C., for opening the inside of the brazing chamber 4 to the atmosphere.
The end 28a of the gas passage 28 for introducing the dry air into the brazing chamber 4 is open. The other end of the gas passage 28 extends outside the furnace body 1, and a gas valve 29 for opening and closing the gas passage is provided on the way. In this manner, the atmosphere opening means according to the present invention is constituted.

The furnace body 1 also has an open end 30a of another gas passage 30 for introducing dry air into the furnace body 1 to open the inside of the furnace body 1 to the atmosphere. Is provided with another gas valve 31 for opening and closing the gas passage.

Below the brazing chamber 4, a hopper 25 as a receiving means according to the present invention is provided. In this hopper 25, the gas valve 29 is opened after vacuum brazing,
Magnesium oxide and the like generated when the inside of the brazing chamber 4 is opened to the atmosphere are collected and guided to a later-described primary cyclone 35 and the like disposed downstream. The hopper 25
A heat reflection plate 26 is provided on the upper part of FIG. A large number of holes 32 are formed in the heat reflecting plate 26 in order to increase the suction force for sucking magnesium oxide and the like in the brazing chamber 4 toward the hopper 25. An inert gas such as N ₂ gas is applied to the heat reflecting plate 26.
A blowing pipe 33 is provided which blows out toward the center of the upper surface of the heat reflecting plate 26, so that the magnesium oxide on the upper surface of the heat reflecting plate 26 rises to improve the suction efficiency.

As shown in FIG. 3, the hopper 25
It is connected to a primary cyclone 35 via a pipe 34. The first pipe 34 is provided with a magnesium recovery valve 36 that opens and closes an internal passage of the first pipe 34. The primary cyclone 35 is connected to the second cyclone 35 through the second pipe 37.
It is connected to the next cyclone 38. Primary cyclone 3
5 has a first magnesium recovery tank 41 for recovering the collected magnesium oxide. A scrubber 39 is provided above (downstream) the secondary cyclone 38, and a fan 40 is provided downstream of the scrubber 39. The secondary cyclone 38 recovers the magnesium oxide collected by the secondary cyclone 38 itself and the scrubber 39.
It has a magnesium recovery tank 42. The second magnesium recovery tank 42 is divided into two tank sections 44 and 4 by a weir 43.
5 are separated. One tank portion 44 is located below the secondary cyclone 38, and the tank portion 44 has
The magnesium oxide collected by the next cyclone 38, the water-insoluble and flame-retardant oil and the magnesium oxide discharged from the shower nozzle 46 in the scrubber 39 flow in, and the magnesium oxide is deposited in a sludge state. The oil overflowing from one tank portion 44 flows into the other tank portion 45. The oil in the other tank part 45 is sucked up by the pump 47, cooled through a heat exchanger (not shown), and discharged from the shower nozzle 46. In FIG. 3, reference numeral 48 denotes a glass ball layer. In addition, primary cyclone 35, secondary cyclone 3
8. The scrubber 39 and the like correspond to the separation and recovery means according to the present invention.

Next, a vacuum brazing method using the aluminum vacuum brazing furnace configured as described above will be described with reference to FIG.
Will be described with reference to FIG.

First, the brazing in the nth cycle is started. In the brazing, the article 6 to be brazed is carried into the brazing chamber 4,
The operation is started with the front door 22 closed, and by closing the front door 22, as described above, the opening solenoid 44 is energized and the closing solenoid 43 is de-energized by the valve drive circuit 38, and the movable wall 12 is opened. Position. Then, the switching valve 60 of the vacuum exhaust system is opened, and the inside of the brazing chamber 4 is evacuated by the diffusion pump 61, the mechanical booster pump 62, and the rotary pump 63. When the evacuation is started, the pressure in the brazing chamber 4 drops as shown in FIG. 8 and the degree of vacuum increases, and since the heater 10 is in an energized state, the brazed article 6 in the brazing chamber 4 is energized. Temperature rises as shown in FIG. Then, as shown in FIG. 8, when the temperature of the brazed article rises to near the magnesium evaporation temperature (for example, 545 ° C.), the output voltage of the temperature sensor 42 becomes equal to or higher than the reference voltage, and as described above, the valve driving circuit 38 The closing solenoid 43 is energized and the opening solenoid 44 is de-energized, and the movable wall 12 is closed. Instead of directly detecting the temperature of the brazed article by the temperature sensor 42,
Noting that the temperature of the brazed article is correlated with the elapsed time after the start of energization of the heater 10, it is assumed that the energization time of the heater 10 has exceeded the required time set based on the experimental data. The temperature of the article to be brazed may be indirectly detected, for example, by a method using a timer.

When the movable wall 12 is closed, magnesium evaporated from the brazing material due to a subsequent increase in the temperature of the brazed article 6 is contained in the brazing chamber 4. Here, when the movable wall 12 is closed, the inner surface of the movable wall 12 is heated by the heater 10 of the movable wall 12, and the wall portion around the gas flow opening of the brazing chamber closed by the movable wall 12 is also different. The movable wall 12 is heated by the heater 10.
Is hardly cooled by the influence of the low temperature furnace body 1 and is in a high temperature state. Therefore, after the movable wall 12 is closed, the evaporated magnesium hardly adheres to the seal between the movable wall 12 and the gas flow port. Therefore, unlike the related art, the movable wall 12 is not completely shielded in the next and subsequent brazing, which causes the degree of vacuum in the brazing chamber 4 to deteriorate, and as a result, the magnesium content in the brazing material becomes a large value. The problem of having to set can be solved. In other words, according to the present embodiment, the magnesium content in the brazing material can be set to a small value. Further, since the complete shielding property of the movable wall 12 is improved, the diffusion pump 61, the mechanical booster pump 62,
It is also possible to solve the problem that the evaporated magnesium is sucked by the rotary pump 63 or the like, which causes the pumps 61, 62, 63 to malfunction.

After that, when the time for the brazing process has elapsed, the inside of the brazing chamber 4 is opened to the atmosphere and the recovery of magnesium oxide is started. To open to the atmosphere, use the gas valve 29
Is performed, and dry air is blown into the brazing chamber 4. At this time, the other gas valves 31 are also opened, and the furnace body 1 is opened.
Dry air is blown into the furnace body 1 and the inside of the furnace body 1 is also opened to the atmosphere.
On the other hand, magnesium oxide recovery is performed by opening the magnesium recovery valve 36 when the fan 40 is rotating or simultaneously with the start of the fan 40. The magnesium recovery is performed until immediately before the start of the brazing in the (n + 1) th cycle.

When the inside of the brazing chamber 4 is opened to the atmosphere, the evaporated magnesium in the brazing chamber 4 is almost oxidized into magnesium oxide (powder). The magnesium oxide has a specific gravity of 2.244 and an average particle size of 20 μm.
The distribution is 4.0% for 2 μm or less, and 21% for 2 to 10 μm.
0%, 25.0% for 10 to 20 μm, 16.0% for 20 to 30 μm, 11.0% for 30 to 40 μm, 40 to 50
μm is 7.5%, 50 to 60 μm is 4.5%, 60 to 7
0 μm is 3.0%, 70 to 80 μm is 2.0%, 80 to
90 μm is 1.0%, 90 to 100 μm is 1.0%, 1
4.0% or more is 4.0%.

Then, the magnesium oxide in the brazing chamber 4 is released from the magnesium recovery valve 36 and the fan 40.
Of the heat reflecting plate 2
6 through the hole 32, the hopper 25, and the first pipe 34, and is led to the primary cyclone 35. Then, most (about 85 to 90%) of the primary cyclone 35 is collected and accumulated in the first magnesium recovery tank 41. Magnesium oxide not collected in the primary cyclone 35
It is led to the next cyclone 38. Then, a part thereof is collected by the secondary cyclone 38 and accumulates in one tank portion 44 of the second magnesium recovery tank 42. The primary cyclone 35 and the secondary cyclone 38 recover about 98% of the sucked magnesium oxide. Then, the remaining magnesium oxide is guided to the scrubber 39, flows into one tank portion 44 of the second magnesium recovery tank 42 together with the oil discharged from the shower nozzle 46, and accumulates in a sludge shape.

When the release to the atmosphere as described above is completed, the front door 22 is opened, the carrier 7 is taken out, the brazed article 6 to be brazed is lowered, and the brazed article 6 to be brazed next to the carrier 7 is removed. After loading, the carrier 7 is loaded, and the front door 22 is closed. When the front door 22 is closed, as described above, the front door closed position detection switch 41 is turned on, and the valve drive circuit 3 is turned on.
8 energizes the opening solenoid 44 and closes the solenoid 43
Is turned off, and the movable wall 12 is opened. And the (n
+1) Start the brazing in the cycle.

As described above, according to the present embodiment,
The magnesium in the brazing chamber 4 is released to the atmosphere
9 makes it possible to oxidize safely and aggressively, as well as cyclones 35 and 38 and scrubber 3
9, etc., the magnesium oxide can be collected automatically and efficiently. Therefore, the cleaning operation for removing the deposits of magnesium oxide can be omitted, and the unoxidized magnesium can be recovered safely.

Although the above-mentioned embodiment is a so-called internal heating type aluminum vacuum brazing furnace, the present invention is not limited to such an internal heating type brazing furnace. Aluminum vacuum brazing furnace (for example, JP-A-63-199070, JP-A-63-199071).
Please refer to Japanese Patent Publication No. ) Can also be applied.

The magnesium recovery apparatus in the above embodiment includes the primary cyclone 35, the secondary cyclone 38 and the scrubber 39. However, if the recovery efficiency and safety can be ensured, only the cyclone or only the scrubber can be configured. You may make it an element.

Further, the scrubber 39 in the above embodiment is used.
Is a wet type in order to increase dust collection efficiency. However, the present invention is not limited to this, and a dry type can be freely used.

Although the above embodiment uses a box type heater, any heater can be used as long as it does not cause insulation failure due to the adhesion of magnesium to the electrode or operation failure due to the adhesion of magnesium near the flow opening of the movable door. A heater may be used.

The shape of the furnace body is not limited to a round shape, but may be a square shape, an elliptical shape, or the like.

Further, in the above-described embodiment, the batch system (the system in which the brazing is performed after opening the brazing after the completion of the brazing) has been described. A system in which a rear chamber is disposed and the brazing chamber is always kept in a vacuum state) may be used in which the brazing chamber or the preheating chamber is periodically opened to the atmosphere according to the load of magnesium to recover magnesium. .

[Brief description of the drawings]

FIG. 1 is a front view schematically showing the inside of a furnace main body of an aluminum vacuum brazing furnace according to one embodiment.

FIG. 2 is a side view schematically showing the inside of a furnace main body.

FIG. 3 is a schematic configuration diagram of a main part of a magnesium recovery device of the aluminum vacuum brazing furnace.

FIG. 4 is a perspective view of a receiving means of the magnesium recovery device.

FIG. 5 is a front view of a heater in the furnace main body.

FIG. 6 is a cross-sectional view of the heater as viewed from a side.

FIG. 7 is a perspective view showing a configuration of a movable wall.

FIG. 8 is a time chart for explaining an aluminum vacuum brazing method using the above aluminum vacuum brazing furnace.

[Explanation of symbols]

 4 Brazing chamber 25 Receiving means 28, 29 Air release means 35, 38, 39 Separation and recovery means

Continuation of the front page (56) References JP-A-62-287054 (JP, A) JP-A-63-52764 (JP, A) JP-A-6-257959 (JP, A) Actually open JP-A 63-127766 (JP) , U)

Claims (1)

(57) [Claims] An aluminum member combined with a brazing material containing magnesium is carried into a brazing chamber, the brazing chamber is evacuated to a vacuum atmosphere, and the temperature is raised to a melting point of the brazing material or higher. An aluminum vacuum brazing furnace for brazing, comprising a magnesium recovery device, which, after brazing is completed, flows air into the brazing chamber and removes magnesium evaporated from the brazing material during brazing. An atmosphere opening means for oxidizing; a receiving means installed below the brazing chamber to receive magnesium oxide generated by the air opening; and a magnesium oxide installed downstream of the receiving means and received by the receiving means. And a separating and collecting means for separating and collecting the aluminum vacuum brazing furnace.