JP2000263279A - Brazing method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent shrink generation in the central part and to achieve uniform brazing by forcedly cooling from the center of the weld zone at the time of cooling of brazing. SOLUTION: Materials to be welded 1, 3, and materials to be welded 2, 5 are attached to an upper and lower jigs 2, 6, respectively, and inserted into a furnace 1 which is kept at a temperature 20-30 deg.C higher than the melting temperature of a brazing filler metal 4. Before being attached to the jigs, the materials 3, 5 to be welded are masked in the areas that need to be free from the deposit of the filler metal. At the moment when the upper and lower jigs 2, 6 and the materials 3, 5 reach the same temperature as that of the furnace 1, the filler metal 4 fused in another equipment is poured in, with the materials fixed by the upper and lower jigs 2, 6. Considering the volume of the weld zone and a volumetric shrinkage due to high temperature, the filler metal 4 10% in excess is used. After the fixing of the upper and lower jigs 2, 6, the furnace is slowly cooled with air (water) jetted out simultaneously from the center of these jigs 2, 6 for forced cooling. Slow cooling is performed at such speed that the temperature in the center becomes lower than in the outer periphery. A reservoir for the filler metal is provided in the outer periphery, supplementing the reduction in the filler metal volume from solidification and shrinkage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method, in which a temperature difference is likely to occur in a brazing material at the time of joining.
Particularly, the present invention relates to a brazing method suitable for a large area and a large brazing thickness. In essence, the example of "joining situation where a temperature difference is likely to occur in the brazing material" is a case where the area is large and the brazing thickness is large. Therefore, a similar situation may occur depending on the thermal conductivity of the brazing material itself.

[0002]

2. Description of the Related Art Brazing is used in various fields, such as mechanical devices, because it can be easily performed if the brazing material melts at a temperature lower than the melting point of a member to be joined and is wet. In practice, it is mainly used when the joint area and brazing thickness are small, so cooling after brazing can be done by a simple method such as natural cooling or oil bath, or forced cooling immersed in a water bath. Bonding could be performed without any problem.

[0003]

However, in the case where a joining area having a relatively large joining area, especially a joining with a large brazing thickness, is required, the cooling method according to the current technology allows the cooling to proceed from the outer peripheral portion while the outer peripheral portion increases. Due to the shrinkage, there is a high possibility that sinking occurs at the center of the joining surface due to the molten central brazing material being brought to the outside, and uniform brazing cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-described problems, and the present invention provides a brazing method and a brazing method which do not cause a bonding problem even when the area is large and the brazing thickness is large. It is intended to provide a device.

[0005]

In order to achieve the above object, in the first and second aspects, when cooling a large-area brazed joint, the brazing is forcibly cooled from the center of the joint. As a result, sink marks generated near the center are prevented, and uniform brazing is enabled.

According to a third aspect of the present invention, a pool of brazing material is provided on the outer peripheral portion. After the brazing material is melted and the objects to be joined are joined, the cooling material is forcibly cooled from the center when cooling, so that the brazing material solidifies and shrinks from the center and reduces the volume of the brazing material. This pool is necessary for the purpose of sufficiently supplying the brazing material. Thereby, when brazing is performed by the joining method of the first and second aspects, sink marks generated at the center of the joining surface can be prevented.

According to a fourth aspect of the present invention, in the brazing apparatus for joining objects to be joined together with a brazing material, the temperature of the outer edge of the object to be joined is maintained at a higher temperature than the center of the joining surface. A cooling means for forcibly cooling from the vicinity and a pool portion for accumulating the brazing material at the outer edge of the joint surface are provided. This makes it possible to realize a joining device capable of easily obtaining a brazed joint that does not cause sink marks at the center.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to make the contents of the present invention easier to understand, the present invention will be described in detail with reference to the following embodiments.

[0009]

EXAMPLE In this example, two metal plates having a diameter of 200 mm × t5 mm and a brazing material capable of wetting both plates were prepared. In the case of a non-wetting metal, a pretreatment may be performed to wet the brazing material.

A plate is attached to the jig shown in FIG. 2 and inserted into a furnace kept at a temperature about 20 to 30 ° C. higher than the melting temperature of the brazing material. When the jig and the object to be joined have the same temperature as the furnace, the wax melted by another device is poured in and the jig is fixed as shown in FIG. The brazing filler is added in consideration of the joint volume and volume shrinkage due to temperature drop,
The volume is assumed to be about 10% extra. Before attaching the plate, a portion where no brazing material can be attached is subjected to a masking process. For this bonding, the bonding thickness was 0.5 mm. After the jig is fixed, the furnace is gradually cooled, and at the same time, air (water) is jetted to the center of the jig as shown in FIG. 1 to perform forced cooling. The slow cooling is performed at such a speed that the temperature at the center is always lower than the temperature at the outer periphery.

Regarding the joined body manufactured as described above,
Table 1 shows the results of inspection using an ultrasonic flaw detector and an X-ray flaw detector. As shown in Table 1, no voids due to sink marks were found.

[0012]

[Table 1]

[0013]

According to the present invention, the following effects are exhibited by the above configuration. In claims 1 and 2, solidification starts from the central part of the brazing material at the joint, and even if the volume shrinks, the molten wax can be replenished from the outside according to claim 3, and the inside of the brazing material Uniform brazing that does not occur can be performed.

According to a third aspect of the present invention, a pool of brazing material is provided on the outer peripheral portion. After the brazing material is melted and the objects to be joined are joined, by forcibly cooling from the center when cooling, it is possible to prevent sink marks occurring at the center of the joining surface.

According to a fourth aspect of the present invention, in the brazing apparatus for joining objects to be joined with a brazing material, the temperature of the outer edge of the object to be joined is maintained at a higher temperature than the center of the joining surface. A cooling device for forcibly cooling from the vicinity and a pooling portion for accumulating a brazing material at an outer edge portion of the bonding surface, so that a brazing device capable of easily obtaining a brazed bonded body that does not generate sink marks in the center portion. Can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a central portion of an apparatus showing an embodiment of the present invention.

FIG. 2 is a view showing a joining jig of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Furnace, 2 ... On a jig, 3 ... Workpiece 1, 4 ... Molten solder
5: Workpiece 2, 2, ... under jig

Claims (4)

[Claims] 1. A brazing method for joining objects to be joined together with a brazing material, wherein cooling is performed from near the center of the joining surface between the objects to be joined during cooling after joining. Brazing method. 2. The brazing method according to claim 1, wherein cooling is performed while maintaining the temperature of the outer edge of the article to be joined at a temperature higher than the center of the joining surface during cooling after the joining. 3. A brazing material according to claim 1, wherein a pool of brazing material is provided at an outer edge of said joining surface so as to compensate for a shortage of brazing material due to solidification and shrinkage during cooling after said joining. Joining method. 4. A brazing joining apparatus for joining objects to be joined together with a brazing material, wherein the temperature of the outer edge of the object to be joined is maintained at a higher temperature than the center of the joining surface, and the temperature is forcibly applied from the vicinity of the center of the joining surface. A brazing joining apparatus comprising: a cooling means for performing a cooling operation; and a pool portion for accumulating a brazing material at an outer edge of the joining surface.