JPS5847268B2 - Brazing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brazing method for providing defect-free brazing results in brazing two metal parts.

Conventionally, when brazing a face-to-face joint, a gap often occurs in the center of the joint surface, which poses a serious problem in terms of joint quality. Figure 1 shows the mechanism by which such a brazing defect occurs. In this figure, a shows a schematic plan view, b shows a schematic side view, and C shows a schematic cross-sectional view.

In the figure, 1 is the upper plate of the metal member constituting the joint, 3 is the supplied brazing material, 4 is the flux applied to the joint joint surface, 5 is the solder filling the joint joint surface, 6 is the unwetted part, and I is the fillet. show.

The inventor closely tracked the situation in which brazing defects occur, and found that in the process of supplying the brazing filler metal 3 and filling the gap between the joints with the solder 5, as shown in the half-white diagram a, the joint joints It has been discovered that wax 5 exhibits a phenomenon in which wax 5 preferentially progresses along the periphery.

This phenomenon also occurred when the supply of wax was not limited to one location as shown in the figure.

In other words, when the brazing filler metal 3 is supplied from one end face as shown in figure a, this phenomenon is judged to be caused by the expanding wetting phenomenon at the joint periphery taking precedence over the phenomenon of spreading due to capillary force within the joint gap. Based on this, before the solder 5 is completely filled in the joint gap, the solder 5 completely spreads to the peripheral edge of the joint forming a closed loop, so the joint gap is closed while leaving an unwetted area 6. to form a fillet 7.

This unwetted area 6 has an internal pressure, and it is impossible to eliminate it even by supplying the brazing filler metal 3 thereafter.

Therefore, in the result of brazing, the part corresponding to this unwetted part 6 remains as a defective part. FIG. Department.

In many cases, flux 4 remains inside this type of defect 8, which is undesirable from the viewpoint of corrosion resistance of the joint. Regarding the behavior of the brazing filler metal 5 filled in the joint, it is possible to preferentially cause the phenomenon of spreading due to capillary force within the gap of the joint, and then to cause the phenomenon of spreading and the formation of a fillet 7 at the peripheral edge of the joint. Periodic brazing provides a method.

FIG. 3 is for detailed explanation of this invention, and a
B shows a schematic plan view, b shows a schematic side view, and C shows a schematic cross-sectional view.

In the figure, reference numeral 9 indicates a notch formed in a part of the peripheral edge of the joint surface of each joint.

By providing the notch 9 in the peripheral edge in this manner, the solder 5 which progresses preferentially due to the expanded wetting phenomenon at the peripheral edge during the rice graining stage is stopped by this notch, and thereafter the solder 5 is caused by capillary force. The spread of the solder 5 becomes preferential, and the solder 5 is preferentially filled in the center of the joint surface.

FIG. 4 shows the situation when the center portion of the joint surface is completely filled with the brazing material, where 10 indicates an unfilled portion of the brazing material, and 11 indicates the brazing material for replenishment.

As shown in the figure, an unfilled portion of the solder material 5 is formed behind the notch portion 9, and this portion is supplemented with the solder material 11 later.

At the same time, the cut portion 9 is also replenished with the brazing material 5.

Note that the area of the unfilled portion 100 of the solder at the rear of the notch 9 changes depending on the shape of the notch 9 and the shape of the joint. It is possible to minimize the area of the filled portion 100 and eliminate the defective portion 8' at the center of the joint surface.

FIG. 5 shows the situation after the filling of the brazing material 5 into the unfilled portions of the brazing material 5 and the notches 9 has been completed.

As shown in this figure, according to the method of the present invention, the central part of the joint gap is filled with solder 5 preferentially, and then the unfilled portion 10 of the solder 5 on the end face of the joint is replenished with brazing filler metal 11. Therefore, the brazing that could not be achieved by the conventional method in which the solder 5 preferentially spreads to the peripheral edge of the joint easily and stably prevents the defective portion 8, and therefore, high-quality brazing can provide a joint.

In the above explanation, a plate material has been taken as an example of a metal member, but the present invention is not limited to this, but can be applied to any type of joint that constitutes a surface joint, and has great effects. play.

Further, the shape of the cut portion may be V-shaped or the like in addition to the shape shown in the figure.

The key is to prevent the wax from spreading around the edges.
A method of applying or sandwiching a material having such a function may also be used.

In other words, the same effect can be achieved by providing a solder advance prevention member.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the defect generation mechanism of brazing produced by conventional brazing methods; Fig. 2 is a schematic diagram showing the results of brazing produced by conventional brazing methods; The figure is a schematic diagram for explaining the first stage process of the embodiment of the present invention, and FIG. 4 is a schematic diagram for explaining the second stage process of the embodiment of FIG. FIG. 5 is a schematic diagram of the completed brazing of the embodiment shown in FIG. 3. 1: Upper plate of the metal member constituting the joint, 2: Lower plate of the metal member constituting the joint, 3: Supply brazing filler metal, 4: Flux 5: Filling braze,
6: Unwetted part, 7: Fillet, 8: Recessed part of solder, 9
: Cut portion, 10: Unfilled portion with brazing material, 11: Replenishment brazing material. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. When two metal members are joined together by brazing, a brazing progress prevention member is provided on a part of the peripheral edge of the joint surface of at least one of the metal members, and at least This is a brazing method in which the central part of the joint surface is completely filled with brazing material, and then the unfilled portion of the peripheral edge is filled with brazing material to perform brazing.