JPH06257959A - Heater for aluminum vacuum brazing furnace - Google Patents

Abstract

PURPOSE:To prevent the generation of heater short-circuit trouble due to adhesion of magnesium evaporated from a brazing material to the electrode unit and the like of the heater and simplify the cleaning work of the heater to remove magnesium oxide. CONSTITUTION:A heater 10 is installed on the internal surface of a wall 8 for a heating chamber for an aluminum vacuum brazing furnace. A heat generating member 15, formed of kanthal wire and the like, and parts of electrode units 16 are received in a box body 13. The opening section of the box body 13 is covered by a heat radiating lid 10a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater for an aluminum vacuum brazing furnace, and more particularly to a heater used for an aluminum vacuum brazing furnace for brazing aluminum products such as heat exchangers for automobiles.

[0002]

2. Description of the Related Art In an aluminum vacuum brazing furnace, an aluminum member in which a magnesium-containing brazing material is combined is carried into a heating chamber inside the furnace body, the heating chamber is placed in a vacuum atmosphere, and the brazing material is heated to its melting point or higher. It is configured to heat and braze the aluminum member. A heater for heating the brazing filler metal to its melting point or higher is arranged in the heating chamber.

By the way, in heating the brazing material, it is desirable to uniformly heat the brazing material. However, in order to heat the brazing material uniformly, the heater is relatively removed from the brazing material. It needs to be placed in a distant position. Therefore, the heater is required to have a high output so that the brazing material can be sufficiently heated even from a relatively distant position. Under the above demands, the conventional heater has a Fe-Cr-Ni structure in which the heat-generating member and the electrode portions (including the insulator) connected to both ends of the heat-generating member are exposed.
The system type heater was the mainstream.

[0004]

However, according to the above-mentioned conventional heater, magnesium evaporated from the brazing filler metal during vacuum brazing adheres to a low temperature portion such as the insulator of the electrode portion, and the insulation resistance of the insulator is lowered, resulting in heater short circuit. There was a risk of an accident.

Further, when the brazed aluminum member is carried out, the heating chamber is opened to the atmosphere. At this time, evaporated magnesium floating in the heating chamber is oxidized and scattered as powdery magnesium oxide. , Adheres to the heat generating member and the electrode part. Therefore, a cleaning operation for removing magnesium oxide adhering to the heat generating member or the like is required as needed, but there is a problem that the cleaning operation is complicated because the shapes of the heat generating member and the electrode portion are complicated.

The present invention solves the above-mentioned problems, prevents the occurrence of a heater short-circuit accident due to evaporated magnesium, and facilitates the heater cleaning work for removing magnesium oxide. The main purpose is to provide.

[0007]

In order to solve the above problems, the heater for an aluminum vacuum brazing furnace according to the present invention carries an aluminum member combined with a magnesium-containing brazing material into a heating chamber inside the furnace body, In an aluminum vacuum brazing furnace for brazing the aluminum member by heating the brazing material to its melting point or higher while making the heating chamber a vacuum atmosphere, the brazing material placed in the heating chamber is heated to its melting point or higher. An aluminum vacuum brazing furnace heater for heating, wherein a heating member and a part of an electrode portion connected to both ends of the heating member are both housed inside a box body, and the electrode is provided on the back side of the box body. The other part is taken out, and the box opening arranged on the aluminum member side is covered with a heat radiation cover that absorbs the heat generated by the heat generating member and radiates it outside. Is the fact characterized.

[0008]

Effect of the Invention Magnesium evaporates from the brazing material during vacuum brazing.

However, since the heat radiation cover that covers the opening of the box body absorbs the heat generated by the heat generating member and radiates the heat to the outside, it has a high temperature so that it functions to reflect the evaporated magnesium. Further, a part of the heat generating member and the electrode portion is housed inside a box whose opening is covered with a heat radiation lid. The other part of the electrode part is taken out from the back side of the box.

Therefore, there is no possibility that evaporated magnesium will adhere to the insulator of the electrode portion, and it is possible to prevent a heater short-circuit accident due to a decrease in the insulation resistance of the insulator.

Further, when the heating chamber is opened to the atmosphere, evaporated magnesium floating in the heating chamber is oxidized and powdered magnesium oxide is scattered.

However, a part of the heat generating member and the electrode portion is housed inside a box whose opening is covered with a heat radiation lid.

Therefore, there is no possibility that magnesium oxide will adhere to a part of the heat generating member and the electrode portion, and it will only adhere to the surface of a heat radiation lid or the like having a simple shape, and the cleaning operation of magnesium oxide will be extremely easy. Become.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 schematically show the whole structure of an aluminum vacuum brazing furnace according to one embodiment.

In FIGS. 1 and 2, reference numeral 1 denotes a furnace body formed in a substantially cylindrical shape in the horizontal direction. An exhaust port 2 of a vacuum exhaust system is provided in the furnace body 1 so as to communicate with the space inside the furnace body. The exhaust port 2 is in communication with a switching valve 60, a diffusion pump 61, a mechanical booster pump 62, and a rotary pump 63, which are components of a vacuum exhaust system. A rail 3 projects from the upper part inside the furnace body 1, and a heater module forming a heating chamber 4 is hung on the rail 3. On the ceiling of the heating chamber 4, there is a carrier rail 5
A carrier 7 on which a product to be brazed (an aluminum member in which a brazing material containing magnesium is combined) 6 is loaded is hung on the carrier rail 5 in a plurality of stages in the vertical direction. The carrier 7 is movable in the direction perpendicular to the paper surface of FIG.

In the case of this embodiment, two heating chambers 4 are formed independently in the lateral direction of FIG. On the inner surface of the side wall 8 except the ceiling and bottom of each heating chamber 4, a pair of heat reflecting plates 9 and heaters 10 serving as heater means are provided, and a plurality of sets are provided corresponding to the position of the brazed product 6. , Installed close to each other. A part 8a of the wall 8 of the heating chamber 4 is, as shown in FIG. 5, a driving means 30 including an air cylinder 11 and the like.
The structure is not limited to the one that rotates as shown in FIG. 5, but can be opened and closed. The heat reflection plate 9 and the heater 10 are also installed in pairs on the inner surface of this portion 8a. Therefore, part of the heating chamber 4 has a structure that can be opened and closed by the movable wall (movable door with heater) 12 as described above. In the case of the present embodiment, two movable walls 12 are provided in each heating chamber 4 on the side surface near the furnace body 1 near the front door 22 and the rear door 23, as shown in FIG. Has been formed. Also, the brazed product 6 is placed in the heating chamber 4
A pair of heat reflection plates 9 and heaters 10 are installed also on the inner surfaces of the front door 22 that is operated when loading and unloading to and from the rear door 23 that is operated during maintenance and inspection.

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

A rotary 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 32 above the ceiling 4 a of the heating chamber 4.
Is connected to the rod 11a of the air cylinder 11 through the movable wall 12 when the rod 11a is at the rear end position.
To the closed position, the rod 11a to the front end position to move the movable wall 12 to the open position, and when the rod 11a advances from the rear end position, the rotary shaft 31 is rotated in the arrow a direction to move the movable wall 12 When the rod 11a is opened from the closed position and the rod 11a is retracted from the front end position, the rotary shaft 31 is rotated in the direction of the arrow b to close the movable wall 12 from the open position. The above-described operation of the air cylinder 11 is performed by the air cylinder 1
In each of the head side chamber 11b and the rod side chamber 11c in 1,
It is realized by supplying and exhausting air 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 which communicate with the inside of the head side chamber 11b of the air cylinder 11 and the inside of the rod side chamber 11c. Rod side chamber 11c
The air hose 34 which communicates with is connected to the port A of the 4-port 2-position switching solenoid valve 36, and the air hose 35 which communicates with the head side chamber 11b is connected to the port B of the solenoid valve 36. The air inlet P of the solenoid valve 36 has, for example, 4 kg / cm.
An air source 37 for generating compressed air ² is connected.

The solenoid valve 36 is driven by a valve drive circuit 38. The valve drive circuit 38 confirms the signal from the open position detecting switch 39 which is turned on when the rod 11a is at the front end position for confirming the open position of the movable wall 12 and the closed position of the movable wall 12. In order to confirm that the signal from the closed position detection switch 40 that is turned on when the rod 11a is at the rear end position and that the front door 22 is changed from the open position to the closed position, the front door 22 is set to the closed position. Temperature sensor 4 that detects a signal from the front door closed position detection switch 41 that turns on when the temperature is high and the temperature of the brazed product 6 in the heating chamber 4 and outputs a signal of a voltage value proportional to the temperature.
The signal from 2 is input. Then, the power supply to the two electromagnetic solenoids 43 and 44 of the solenoid valve 36 is controlled based on these input signals. Here, the one electromagnetic solenoid 43 is connected to the movable wall 12
Is a closing solenoid that is energized when it is rotated or maintained in the closed position, and the other electromagnetic solenoid 44 is the movable wall 12
Is an opening solenoid that is energized when rotating or maintaining the open position.

The valve drive circuit 38 energizes the closing solenoid 43 when the movable wall 12 is in the closed position. At this time, the rod 11a is at the rear end position, and the closed position detection switch 40 is in the ON state. When the movable wall 12 is in the closed position, the front door 2 is started to start brazing.
When 2 is closed, the front door closed position detection switch 41 is turned on, and 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 Therefore, 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 advances, and the movable wall 12 opens. By this opening operation of the movable wall 12, the closed position detecting switch 40 is turned off and the open position detecting switch 39 is turned on. afterwards,
When the temperature of the brazed product 6 in the heating chamber 4 rises and reaches near the evaporation temperature of magnesium (for example, 545 ° C.), the output voltage of the temperature sensor 42 becomes higher than the reference voltage, so the closing solenoid 43 is energized. Also, the opening solenoid 44
De-energize. 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 retracts, and the movable wall 12 closes.

The product 6 to be brazed is an aluminum heat exchanger such as a radiator for automobiles, an evaporator for automobile air conditioning, a condenser, etc. The brazing material for brazing is a composition as shown in Table 1 below. According to the present embodiment, the magnesium content is reduced from 1.2% to 0.6%.

[0025] Each heater 10 is configured as shown in FIGS. 3 and 4.

In FIGS. 3 and 4, reference numeral 13 denotes a box body made of stainless steel or the like. Box 1
3 has a thickness of 1.2 mm, a plurality of heat generating member support rods 14 supported by the box body 13 are arranged inside, and a heat generating member 15 is wound around each heat generating member support rod 14. . The heat generating member 15 is made of a material such as Kanthal wire. Both ends of the heat generating member 15 are connected to the electrode portions 16, respectively. Each electrode portion 16 is fixed to the electrode rod 17 having the end portion 15a of the heat generating member 15 fixed to one end, the ceramic insulator 18 arranged on the outer periphery of the electrode rod 17, and the other end of the electrode rod 17. It is composed of a bolt 19 and a terminal 20 fixed to the other end of the electrode rod 17 by the bolt 19 and having a tip of a heater cable 27 fixed thereto.
Here, as is clear from FIG. 4, a part of the ceramic insulator 18 is housed inside the box body 13, and the other part is inside the box body 13.
Is taken out from the back surface 10b. On the floor surface of the box body 13, one or a plurality of heat reflection plates 21 for preventing heat radiation are arranged. The heat reflecting plate 21 is made of stainless steel or the like and has a thickness of 0.5 mm. The opening of the box 13 is covered with a removable heat radiation lid 10a. The heat radiation lid 10a is made of stainless steel or the like, has a thickness of 1.2 mm, and has a maximum surface temperature of 800 ° C.
Guaranteed up to. The heating member 15 of the aluminum vacuum brazing furnace heater 10 shown in FIGS. 3 and 4 has a coil shape, but is not limited to this.
Alternatively, it may have a band shape.

As shown in FIG. 4, the heater 10 constructed as described above has one or a plurality of heat reflecting plates 9 on the inner surface side of the frame forming the wall 8 of the heating chamber 4. Installed above. In addition, the heater 10 has a front door 22.
Also, it is attached to each inner surface of the rear door 23 in the same manner as above.

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

Below the heating chamber 4, a hopper 25 is provided in the furnace body 1 for collecting magnesium oxide and the like generated by opening the heating chamber 4 to the atmosphere after vacuum brazing, A heat reflection plate 26 is provided above the hopper 25.

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, brazing in the nth cycle is started. Brazing is started with the brazed product 6 carried into the heating chamber 4, and the front door 22 is closed. By closing the front door 22, the opening solenoid is opened by the valve drive circuit 38 as described above. 44 is energized, the closing solenoid 43 is de-energized, and the movable wall 12 is in the open position. Then, the switching valve 60 of the vacuum exhaust system is opened, and the diffusion chamber 61, the mechanical booster pump 62, and the rotary pump 63 start exhausting the inside of the heating chamber 4. When the exhaust starts, the pressure in the heating chamber 4 drops as shown in FIG. 6 and the degree of vacuum increases, and since the heater 10 is in the energized state, the temperature of the brazed product 6 in the heating chamber 4 increases. Rises as shown in FIG. Then, as shown in FIG. 6, when the temperature of the brazed product 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,
As described above, the valve drive circuit 38 energizes the closing solenoid 43 and deenergizes the opening solenoid 44, and the movable wall 12 is closed. Note that instead of the method of directly detecting the temperature of the brazed product by the temperature sensor 42, the temperature of the brazed product is correlated with the elapsed time after the start of energization of the heater 10, The temperature of the brazed product may be indirectly detected by, for example, a method in which the timer means determines that the energization time to the heater 10 has exceeded the required time set based on the experimental data.

When the movable wall 12 is closed, the magnesium evaporated from the brazing material due to the subsequent temperature rise of the brazed product 6 is enclosed in the heating chamber 4. Here, when the movable wall 12 is closed, the inner surface of the movable wall 12 is
Since the wall portion around the gas flow port of the heating chamber that is heated by the second heater 10 and is closed by the movable wall 12 is also heated by the other heater 10, the inner surface of the movable wall 12 and the periphery of the gas flow port. The wall portion of is almost never 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, evaporated magnesium hardly adheres to the seal portion between the movable wall 12 and the gas flow port.

After that, when the time for the brazing process elapses, the inside of the heating chamber 4 is opened to the atmosphere. Although not shown in the drawing, the opening of the atmosphere to the atmosphere passage from the furnace body 1 to the atmosphere is
It is performed by opening the closed state until then. By opening to the atmosphere, most of the magnesium in the heating chamber 4 is oxidized into magnesium oxide (powder), and the magnesium oxide and the residual magnesium are recovered by a magnesium recovery device (not shown) having the hopper 25 as a constituent element. To be done.

After that, the front door 22 is opened, the carrier 7 is taken out, the brazed product 6 to be brazed is lowered, the brazed product 6 to be brazed next is loaded on the carrier 7, and the carrier 7 is removed.
And close the front door 22. When the front door 22 is closed, as described above, the front door closed position detection switch 41 is turned on, the valve drive circuit 38 energizes the opening solenoid 44 and deenergizes the closing solenoid 43, and the movable wall 12 is closed. Is opened. Then, the brazing in the (n + 1) th cycle is started.

As described above, according to this embodiment,
The ceramic insulator 18, which is a constituent element of the electrode portion 16 of the heater 10, is located inside and on the back side of the box body 13, and the heat radiation lid 10a that covers the opening of the box body 13 has a high temperature, and the evaporated magnesium emits heat. Since the surface of the lid 10a is reflected as it is and does not enter the inside and the back of the box body 13, the evaporated magnesium hardly adheres to the ceramic insulator 18, and therefore the insulation of the ceramic insulator 18 is deteriorated due to the adhered magnesium. Based on this, it is possible to prevent a heater short circuit accident.

Further, according to this embodiment, the heat generating member 15 and a part of the electrode portion 16 are accommodated in the box body 13, and
Since the heat radiation lid 10a is covered on the opening of
When the heating chamber 4 is opened to the atmosphere, powdered magnesium oxide, which is evaporated due to oxidation of evaporated magnesium, does not adhere to the heat generating member 15 and the electrode portion 16 or the like, and is attached to the flat surface of the heat radiation lid 10a or the like. It only adheres. Therefore, the cleaning work for removing magnesium oxide is extremely simple.

Further, comparing the aluminum vacuum brazing furnace heater 10 of this embodiment with a conventional bare type heater,
In the case of a heater with vertical and horizontal dimensions of 425 mm x 380 mm,
The maximum temperature difference between the heaters was about 150 ° C. in the conventional heater, but the maximum temperature difference was about 50 ° C. in the aluminum vacuum brazing furnace heater 10 of this embodiment.
Then, this temperature difference was as small as about 20 ° C. when the aluminum vacuum brazing furnace heater 10 was placed in a vacuum. As described above, according to the aluminum vacuum brazing furnace heater 10 of the present embodiment, the soaking property is remarkably improved as compared with the conventional bare type heater.

When the aluminum vacuum brazing furnace heater 10 of this embodiment is applied to the aluminum vacuum brazing furnace as described above, the aluminum vacuum brazing furnace heater is opened by opening the front door 22 after the brazing is completed. The temperature of 10 is 40
Although the temperature dropped to about 0 ° C., this temperature drop was about 200 ° C. less than that of the conventional exposed heater. For this reason,
According to the aluminum vacuum brazing furnace heater 10 of the present embodiment, the heat insulating property of the heater, that is, in the period from the opening of the front door 22 to the closing of the front door 22 for the next brazing after the brazing is completed. The heater performance of keeping the temperature in the heating chamber 4 at a high temperature is significantly improved as compared with the conventional bare-type heater, which is excellent in energy saving.

[Brief description of drawings]

FIG. 1 is a front view showing the inside of an aluminum vacuum brazing furnace to which a heater for an aluminum vacuum brazing furnace according to an embodiment is applied.

FIG. 2 is a side view showing the inside of the aluminum vacuum brazing furnace.

FIG. 3 is a front view of the heater for the aluminum vacuum brazing furnace.

FIG. 4 is a cross-sectional view of the heater seen from a side surface side.

FIG. 5 is a perspective view showing a configuration of a movable heater.

FIG. 6 is a time chart for explaining an aluminum vacuum brazing method using the aluminum vacuum brazing furnace.

[Explanation of symbols]

 4 Heating Chamber 10 Aluminum Vacuum Brazing Furnace Heater 10a Heat Radiation Lid 13 Box 15 Heat Generation Member 16 Electrode Part

Front page continued (72) Inventor Hiroto Hayashi 1-1, Showa-cho, Kariya city, Aichi Prefecture

Claims (1)

[Claims] 1. An aluminum member in which a magnesium-containing brazing material is combined is loaded into a heating chamber inside a furnace body, the heating chamber is placed in a vacuum atmosphere, and the brazing material is heated to a temperature equal to or higher than its melting point to obtain the aluminum member. In an aluminum vacuum brazing furnace for brazing, a heater for an aluminum vacuum brazing furnace arranged in the heating chamber to heat the brazing material to its melting point or higher, the heating member being connected to both ends of the heating member. Part of the electrode part is housed inside the box body, the other part of the electrode part is taken out on the back surface side of the box body, and the heat generation is performed in the box body opening part arranged on the aluminum member side. A heater for an aluminum vacuum brazing furnace, which is formed by covering a heat radiation cover that absorbs heat generated by a member and radiates the heat to the outside.