JPH0579765A - Vacuum aluminum brazing furnace - Google Patents

Abstract

PURPOSE:To prevent pollution of the inside of a furnace and an influence on the quality of products due to an excessive evaporation of magnesium by providing a measuring instrument which measures the concentration of magnesium in a heating compartment and a driving device that takes a magnesium evaporation source in or out from the heating compartment according to the measurements of the measuring instrument. CONSTITUTION:When the concentration of magnesium is detected by a measuring instrument 15 with an evaporation source 12 placed outside a heating compartment 3 and the measurement is less than the specified value, a controller 18 brings a cylinder 10 into action so that a cylinder rod 11 extends to insert the evaporation source 12 into the heating compartment 3. As a result, evaporation of magnesium from the evaporation source 12 is stimulated, causing an increase in the concentration of magnesium in the heating compartment 3. When the concentration exceeds the specified value with the evaporation source 12 inserted inside the heating compartment 3, the controller 18 brings the cylinder into action so that the cylinder rod 11 retracts and pulls the evaporation source 12 out from the heating compartment 3. Thereby, the concentration of magnesium in the heating compartment 3 is maintained at the specified value.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vacuum aluminum brazing furnace for brazing aluminum products.

[0002]

2. Description of the Related Art As is well known, it is essential that a brazing material for brazing aluminum products contains magnesium as a getter material for oxygen. That is, when brazing aluminum products in a vacuum aluminum brazing furnace, if oxygen gas or water is present in the atmosphere in the furnace, an aluminum oxide film is formed on the part to be brazed Therefore, in order to prevent such a situation, magnesium having a higher affinity for oxygen than aluminum is contained in the brazing filler metal and magnesium is evaporated together with the brazing filler metal during the treatment to prevent It combines oxygen and water with magnesium and removes it as magnesium oxide.

In some cases, the amount of magnesium contained in the brazing material is insufficient to remove oxygen and water sufficiently. In such a case, pure magnesium and other magnesium evaporation sources may be used. Brazing sheet (equivalent to brazing filler metal containing magnesium)
Is placed in the furnace together with the object to be treated, which is called so-called "placed magnesium".

[0004]

However, when the treatment is carried out by placing magnesium as described above, it is not possible to freely control the evaporation amount of magnesium from the magnesium evaporation source, and therefore the magnesium evaporation source is used. Magnesium in excess of the amount required for oxygen removal may evaporate. When magnesium evaporates excessively, it adheres to various parts inside the furnace and contaminates the inside of the furnace, so not only frequent cleaning is required, but also
There is a problem that excessively evaporated magnesium may dissolve in the molten brazing filler metal and adversely affect the quality of the product.

[0005]

In view of the above circumstances, the present invention has as its object to provide a vacuum aluminum brazing furnace capable of freely controlling the amount of evaporation from a magnesium evaporation source (placed magnesium). In addition, the furnace body, a heating chamber provided inside the furnace body, and a heating chamber that can be freely inserted into and removed from the heating chamber, and magnesium is evaporated by being loaded into the heating chamber during processing. A source, a measuring device for measuring the magnesium concentration in the heating chamber, and a drive device for moving the magnesium evaporation source into and out of the heating chamber based on the measurement result of the measuring device. is there.

[0006]

In the vacuum aluminum brazing furnace of the present invention, the magnesium evaporation source, which is the placed magnesium, is provided so that it can be freely taken in and out of the heating chamber by the drive device, and the magnesium concentration in the heating chamber is measured by the measuring device during brazing. If the measured magnesium concentration is less than the specified value, the evaporation source is charged into the heating chamber to evaporate magnesium, and if the magnesium concentration in the heating chamber exceeds the specified value, the evaporation source is removed from the heating chamber. By taking out and suppressing further evaporation, the magnesium concentration in the heating chamber is maintained at a predetermined value.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram of a vacuum aluminum brazing furnace of this embodiment, in which reference numeral 1 is a furnace body which is a vacuum container, 2 is its door, and 3 is a heating chamber provided inside the furnace body 1. Reference numeral 4 denotes a door thereof, 5 denotes an object to be processed, 6 denotes a support stand for supporting the object to be processed, and 7 denotes a heater.

An opening 8 is provided in the center of the bottom surface of the heating chamber 3, and the opening 8 is opened and closed by a shutter 9 that slides in the horizontal direction (the front and back directions of the paper in the drawing). Further, a cylinder (driving device) which is operated at the center of the bottom surface of the furnace body 1 by hydraulic or pneumatic pressure to extend and retract the cylinder rod 11 in the furnace body 1.
10 is provided facing upward, and a magnesium evaporation source 12 (pure magnesium or placed magnesium such as a brazing sheet) is provided at the tip of the cylinder rod 11. Then, by extending the cylinder rod 11 upward, the evaporation source 12 passes through the opening 8 of the heating chamber 3 and enters the heating chamber 3 as shown by the chain line in the figure, and the cylinder rod 11 Is retracted downward so that the evaporation source 12 is taken out of the heating chamber 3 as shown by the solid line in the figure. Further, the cylinder rod 11 is provided with a lid 13 that closes the opening 8 when the evaporation source 12 is loaded into the heating chamber 3.

Further, the furnace of this embodiment has a measuring device 15 for measuring the concentration of magnesium vapor in the heating chamber 3.
Is provided. The measuring device 15 is composed of a measuring device body 16 such as a mass spectrometer and a suction nozzle 17 for sucking a sample gas from the inside of the heating chamber 3, and the magnesium concentration in the heating chamber 3 during the brazing process. Is measured continuously or intermittently. And
The cylinder 10 is controlled by the controller 18 based on the measurement result.

That is, when the evaporation source 12 is outside the heating chamber 3 and the concentration measured by the measuring device 15 does not reach the preset predetermined value, the control device 18 extends the cylinder rod 11. Thus, the cylinder 10 is operated to load the evaporation source 12 into the heating chamber 3 to promote the evaporation of magnesium from the evaporation source 12 and increase its concentration. Further, in a state where the evaporation source 12 is charged in the heating chamber 3, if the magnesium concentration in the heating chamber 3 exceeds a predetermined value, further evaporation is prevented to reduce the concentration. The controller 18 operates the cylinder 10 so as to retract the cylinder rod 11, and pulls the evaporation source 12 out of the heating chamber 3. Thereby, the magnesium concentration in the heating chamber 3 is maintained at a predetermined value.

When the evaporation source 12 is outside the heating chamber 3, the shutter 9 of the opening 8 is always closed. Although the shutter 9 is opened when the evaporation source 12 is loaded into the heating chamber 3, the opening 8 is automatically closed by the lid 13 at the same time when the evaporation source 12 is loaded. In addition, the evaporation source 12
It is necessary to close the shutter 9 promptly after taking out the heating source from the heating chamber 3, and the opening and closing of the shutter 9 is linked to the withdrawal of the evaporation source 12 and the control device 1 described above.
8 may be used for control.

An example of the operation procedure of the vacuum aluminum brazing furnace having the above structure will be described below. First, the evaporation source 12 is placed outside the heating chamber 3 and the shutter 9 is closed. In that state, the workpiece 5 is placed inside the heating chamber 3 and the doors 4 and 2 are closed. Thus, the entire furnace body 1 is evacuated, and when a predetermined degree of vacuum is reached, the heater 7 is energized to perform initial heating. At that stage, the moisture attached to the object to be processed 5 evaporates and the degree of vacuum temporarily decreases. Therefore, the evacuation is further continued until the predetermined degree of vacuum is reached. At this time, if the predetermined degree of vacuum cannot be reached only by performing vacuuming, the evaporation source 12
The steam in the heating chamber 3 may be removed by temporarily charging the heating chamber 3 to evaporate magnesium.

When the inside of the heating chamber 3 reaches a predetermined degree of vacuum, main heating is performed to further raise the temperature inside the furnace to melt the brazing material previously attached to the object 5 to be brazed. Do. At this time, as described above, the magnesium concentration in the heating chamber 3 is measured by the measuring device 15, the cylinder 10 is operated based on the measurement result, and the evaporation source 12 is put into and taken out of the heating chamber 3, The magnesium concentration in 3 is maintained at a predetermined value.

By the above, the magnesium concentration in the heating chamber 3 can be properly maintained, and therefore water and oxygen in the furnace can be surely removed, and magnesium is excessively evaporated. It is possible to prevent problems caused by doing so, that is, excessive evaporation of magnesium adheres to the inside of the furnace, which necessitates frequent cleaning and adversely affects product quality.

In the above embodiment, the evaporation source 12 is moved up and down by the cylinder 10 so that the evaporation source 12 is moved in and out from the bottom of the heating chamber 3. However, as a driving device for moving the evaporation source 12 in and out, Of course, not only the cylinder 10 but also an appropriate mechanism can be adopted. Also,
In the above embodiment, the control device 18 automatically controls the cylinder 10 based on the measurement result of the measurement device 15. However, by observing the measurement result, the drive device such as the cylinder is manually operated. May be.

[0016]

As described in detail above, since the vacuum aluminum brazing furnace of the present invention is constructed so that the evaporation source is put into and taken out of the heating chamber based on the magnesium concentration in the heating chamber, It is possible to maintain the concentration appropriately, and therefore it is possible to prevent problems such as the inside of the furnace being contaminated by the excessively evaporated magnesium, and the product quality being adversely affected.
It is extremely effective in terms of maintenance and quality control.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a vacuum aluminum brazing furnace that is an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 furnace main body 3 heating chamber 5 object to be treated 10 cylinder (driving device) 12 magnesium evaporation source 15 measuring device 18 control device.

Claims (1)

[Claims] 1. A furnace main body, a heating chamber provided inside the furnace main body, and magnesium which is provided so as to be freely inserted into and removed from the heating chamber and which is evaporated into the heating chamber during processing. A vacuum comprising an evaporation source, a measuring device for measuring the magnesium concentration in the heating chamber, and a drive device for moving the magnesium evaporation source into and out of the heating chamber based on the measurement result of the measuring device. Aluminum brazing furnace.