JP3235975B2 - Method for brazing Mg-containing aluminum alloy material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for brazing a magnesium-containing aluminum alloy material by heating and brazing the surface of a brazing material in which a brazing material is clad on a core material of an aluminum alloy. About.

[0002]

2. Description of the Related Art Conventionally, Mg-containing aluminum alloy materials are:
It is widely used as a member of various aluminum products that require strength.

[0003] When such a member made of an aluminum alloy material containing Mg is bonded to a base material of an aluminum alloy and assembled into various products such as a radiator for an automobile, an evaporator for a car air conditioner, and a capacitor, the base material is used as the base material. A method is used in which a brazing material in which a brazing material is clad on an aluminum alloy core material is used, and a non-corrosive fluoride-based flux is applied to the joining surface of the brazing material, followed by heating and brazing.

However, in such a brazing method, Mg in the Mg-containing aluminum alloy material, which is a member, and F in the flux react with each other, and MgF ₂ or the like adheres to the joining surface of the aluminum alloy material, which is the base material. A needle-like or powdery reaction product was formed, which hindered the spread of the brazing material and did not allow sufficient bonding between the substrate and the member.

On the other hand, for example, the content of Mg in an Mg-containing aluminum alloy material is kept low to reduce the formation of reaction products, or a high-concentration fluoride-based flux suspension or powder is used. Although measures such as application of a fluoride-based flux are taken, they do not necessarily promote the wetting and spreading of the brazing material, and it is still not possible to achieve sufficient bonding.

In particular, when the member is small, such as a pipe joint member attached to the header of a condenser for a car air conditioner, the contact area with the header as a brazing material is originally very small. If the brazing material is not sufficiently wet-spread, it is difficult to bring the brazing material of the brazing material into wide contact with the joining surface of the member, and the torque crushing strength of the pipe joint member is not practical. The result is that only values in the range are obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a brazing material for joining a Mg-containing aluminum alloy material to a brazing material by using a fluoride-based flux. An object of the present invention is to provide a method of brazing an Mg-containing aluminum alloy material that can exhibit excellent brazing properties.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned object, the present invention provides a method for applying a fluoride-based flux to an Mg-containing aluminum alloy material on the surface of a brazing material clad with a brazing material. Brazing material and M
0.1 to 0.5 mm between g-containing aluminum alloy material
The gist of the present invention is to provide a method for brazing an Mg-containing aluminum alloy material, characterized by providing a gap for filling a brazing material.

The aluminum alloy material as a member to be subjected to the brazing method of the present invention is an aluminum alloy material containing Mg, and the content of Mg is usually adopted in order to improve the mechanical strength of the material. Any content may be used as long as it is within a certain range, and for example, a Mg-containing aluminum alloy material having a Mg content of 0.4 wt% to 6.0 wt% is suitably applied.

In the brazing method according to the present invention, the brazing material as a mating member to which the above-mentioned members are joined is formed on one or both sides of a core material made of an aluminum alloy by using a brazing alloy such as an Al-Si type. Clad plywood,
Or a secondary molding material such as an electric resistance welded tube formed from this laminated plate,
Alternatively, a seamless pipe or the like obtained using a composite billet is applied.

Further, the flux used in the brazing method of the present invention is mainly composed of a non-corrosive fluoride-based flux, and has a eutectic composition of potassium fluoride (KF) and aluminum fluoride (AlF3). It may be a single composition of a complex compound such as KAlF4, K2 AlF5 or K3 AlF6 substantially complexed with a substance, or a mixed composition of two or more of these. Each of these compositions is in the form of a powder or a suspension with water or another solvent.

In the brazing material filling gap (S), when brazing, Mg in the member and F in the flux are formed by the brazing material.
This serves to fill the brazing material itself in a state of spreading while wetting out the MgF ₂ or the like, which is a reaction product of the brazing material, with the gap width, that is, the brazing material and the Mg-containing aluminum alloy material. 0.1
When the thickness is less than 0.1 mm, the flow of the flux and the filling of the brazing material become insufficient, and when the thickness exceeds 0.5 mm, a broken portion is generated due to the breakage of the brazing material. Preferably, it should be at least 0.2 mm. It should be 0.4 mm or less.

Further, as shown in FIG. 1A, the value of the gap (S) for filling the brazing filler metal is such that the distance between the base material (A) and the member (B) is a constant value (d1) within the above numerical range. )
As shown in FIG. 1B, the distance between the base material (A) and the member (B) gradually decreases from the outside to the inside of the joining surface of the two materials (d
2> d3), and when the joining surfaces of both materials are not parallel and gradually decrease from one side to the other as shown in FIG. 1 (c), the numerical values (d4> d5) are all within the above numerical range. Should be there.

In the present invention, a brazing filler gap (S) of 0.1 to 0.5 mm is previously provided between a base material made of a brazing material and a member made of an Mg-containing aluminum alloy material.
The brazing filler gap (S) is generally formed such that the distance (D1) between the joining surfaces of the base material (A) and the member (B) is within the above numerical range. A member which is arranged and formed by an arbitrary means (FIG. 2) or which is cut as a member (B) such that a part of its joint surface remains as a bearing (t) having a height (D2) within the above-mentioned numerical value. (FIG. 3) or a substrate having a concave portion (v) having a depth (D3) within the above numerical range on the surface corresponding to the member (B) as the substrate (A). (FIG. 4), but is not necessarily limited thereto. Normally, as shown in FIG. 3, a member whose joint surface is cut so that a part thereof remains as a support portion (t) is used. However, when brazing, the member (B) can be easily positioned. This is reliable, and is advantageous in terms of quality such as brazing accuracy and strength, and cost.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
The embodiment will be described with reference to the drawings. The embodiment described below is applied to the attachment of a pipe joint for connecting a heat medium introduction pipe and a discharge pipe to a tubular body such as a header in a car air conditioner condenser.

FIG. 5 shows a condenser for a car air conditioner. The condenser (1) is composed of a plurality of flat tubes (2) extending in the horizontal direction and arranged at predetermined intervals in the vertical direction.
And cylindrical inlet-side headers (3) and outlet-side headers (4) to which both ends of each flat tube (2) are connected, and aluminum corrugated fins disposed between adjacent flat tubes (2). The pipe joint (6) is attached to the upper part of the inlet side header (3) and the lower part of the outlet side header (4). The mounting configuration of each pipe joint (6) is the same in both headers (3) and (4). The exit side header (4) has a brazing material (4b) on both sides of a core material (4a) of an aluminum alloy.
Is formed by electric resistance welding from a plate-shaped brazing material on which cladding is formed, and has a tubular body in which a through hole (4c) is formed. The structure of such a car air conditioner capacitor is disclosed in, for example, Japanese Utility Model Publication No. 6-27257.

As shown in FIGS. 6A and 6B, the pipe joint (6) includes a brazing ring (a brazing material) disposed around the through hole (4c) of the header (4). 7) and a pipe joint member (8) attached via the brazing ring (7). The brazing ring (7) is made of an aluminum alloy core material (7).
a) and a brazing material (7b) covering both surfaces of the core material (7a) from a plate-shaped brazing material, by pressing, the upper surface is made flat and the lower surface is a concave curved surface along the wall surface of the header (4). And an insertion hole (7c) corresponding to the through hole (4c) of the header (4).

Further, the pipe joint member (8) is made of an Mg-containing aluminum alloy material and, as shown in FIG. 7, an outward flange (8a) having a hexagonal outer peripheral surface at an intermediate portion of the length. ) Are integrally provided, and the flange (8)
A connecting portion (8b) formed with a male screw (n) for connecting a cap nut (not shown) for connecting the discharge pipe to the outer peripheral surface is provided on the upper end side of the flange (8a). Also at the lower end side, a cylindrical portion (8c) to be inserted into the through hole (4c) of the header (4) is provided.

The lower surface of the pipe joint member (8) is cut from the outside to the inside, and a part of the inside is supported (t).
When the flange (8a) and the brazing ring (7) are combined, the space between the lower surface of the flange (8a) and the upper surface of the brazing ring (7) is formed. A brazing filler gap (S) is formed. The height of the bearing (t) provided on the lower surface of the flange (8a) is as follows:
It is set within the range of 0.1 to 0.5 mm.

With such a configuration, the through hole (4c) of the header (4) and the insertion hole (7c) of the brazing ring (7) are provided.
A brazing ring (7) is arranged on the header (4) in such a manner that the tubular portion (8c) of the pipe joint member (8) is inserted into the through hole (4c) through the insertion hole (7c). Then, after filling the brazing filler gap (S) formed between the brazing ring (7) and the flange (8a) with flux, the header (3) made in the same manner as the header (4) is formed. Between the flat tube (2) and the corrugated fin (5)
Are assembled in a conventional manner, and then put into a heating furnace and subjected to heating brazing.

[0021]

【Example】

Example 1 As a pipe joint member as a member, as shown in FIG.
It consists of a square nut-like flange (8a), a connecting part (8b) and a cylindrical part (8c), and the lower surface of the flange (8a) is a ring with a width of 2 mm and a thickness of 0.3 mm from outside to inside. Mg content 0.35 to 0.55 wt%, with a bearing (t) with a width of 2 mm left inside in a ring shape
Five pipe joint members (8) made of the above-mentioned Mg-containing aluminum alloy material were prepared.

Further, a tubular body (4) made of an aluminum alloy having an outer diameter of 24 mm and a wall thickness of 1.5 mm, and an Al-Si brazing alloy on both surfaces serving as a base material of the pipe joint member (8).
Five brazing rings (7) each having the same shape as shown in FIGS. 6 and 7 and clad with 5 wt% were prepared. The gap (S) for filling the brazing material at this time is 0.3 mm.

Next, the pipe joint member (8) is set on the tubular body (4) via the brazing ring (7) as shown in FIG. 6, and the brazing material formed thereby is filled. After the gap (S) was filled with a fluoride-based flux containing a brazing material, it was placed in a heating furnace and heated and brazed to prepare five brazing samples.

The torque fracture strength of each of the brazed pipe joint members (8) was measured for the five samples (N1 to N5), and as a result, as shown in Table 1, 450 to 550 kgf.
The values in the range of cm were shown.

The sample after measuring the torque fracture strength was cut along the axis of the pipe joint member (8), and the cut surface was visually observed. In the filled state, there was evidence that the brazing filler metal was sufficiently filled. The flange (8a) of the pipe joint member (8) is in contact with the brazing ring (7), that is, between the bearing (t) of the flange (8a) and the brazing ring (7). In any of the samples, traces of filling with brazing material were hardly observed. From this, it can be seen that the improvement of the bonding strength by brazing the base material (A) and the member (B) is preferably achieved by increasing the area of the brazing filler gap (S) as much as possible.

[0026]

[Table 1]

COMPARATIVE EXAMPLE 1 In Example 1, the pipe joint member (8) was not cut on the lower surface of its flange (8a), and was a ring-shaped flat plate having a width of 4 mm from the inside to the outside. A pipe joint member (8), a tubular body (4) and a brazing ring (7) were prepared which were all the same as in Example 1 except for the parts. The brazing filler gap (S) at this time is zero.

Then, a suspension of a fluoride-based flux is applied to the lower surface of the flange (8a) of the pipe joint member (8) on the tubular body (4), and the brazing ring (7) is attached. After that, it was set in the same manner as in Example 1 and then placed in a heating furnace and brazed by heating to prepare five brazed samples.

With respect to the five samples (N11 to N15), the torque fracture strength of each brazed pipe joint member (8) was measured in the same manner as in Example 1. As a result, as shown in Table 1, , In the range of 100 to 200 kgf · cm.

Further, the sample after measuring the torque breaking strength was cut along the axis of the pipe joint member (8) in the same manner as in Example 1, and the cut surface was visually observed. A fillet of brazing material was found in the corner of the brazing ring (7), but any contact surface between the flange (8a) of the pipe joint member (8) and the brazing ring (7) was found. There was almost no trace of the filler filled with the brazing material.

Example 2 As shown in FIG. 8, the same tubular body (4) and brazing ring (7) as used in Example 1 and the same pipe joint member (8) as used in Comparative Example were used. The pipe joint member (8) is disposed so as to be inclined with respect to the brazing ring (7), and an outer peripheral portion of a flange (8a) of the pipe joint member (8) and the brazing ring (7). ) Were prepared by changing the brazing filler gap (S) consisting of a large gap (L) and a small gap (R) from the upper surface of the sample to the values shown in Table 2. Similarly, braze three pieces (N
6 to N8) Prepared.

The sample obtained above was cut along the axis of the pipe joint member (8), and the cut surface was visually observed. As a result, as shown in Table 2, the solder in the brazing filler gap (S) was obtained. Except for a slight break in the material in sample N6,
Not at all.

[0033]

[Table 2]

Comparative Example 2 Example 2 was repeated except that the gap (L) in Example 2 was set to a value exceeding 0.5 mm and was changed as shown in Table 2.
Three brazes (N16 to N18) were prepared in exactly the same manner as in the above. As a result of visual observation of each of the obtained samples in the same manner as in Example 2, as shown in Table 2, the brazing material was cut off on the gap (L) side in the gap (S) for filling with the brazing material. From this, it can be inferred that when the brazing filler gap (S) exceeds 0.5 mm, the joining strength varies and a high torque breaking strength cannot be obtained.

In the brazing method of the present invention, even if a member made of an Mg-containing aluminum alloy is brazed to a base made of a brazing material by applying a fluoride-based flux to the base, the member formed between the base and the member can be brazed. It becomes possible to sufficiently fill the brazing material.

[0036]

As described above, according to the present invention, when a brazing material clad with a brazing material is heated and brazed with a Mg-containing aluminum alloy material by applying a fluoride flux to the surface of the brazing material, the brazing material and the Mg Since a gap for filling the brazing filler metal of 0.1 to 0.5 mm is provided between the aluminum alloy material containing Mg and the reaction product of Mg in the aluminum alloy material containing Mg and F in the fluoride-based flux. The brazing filler metal wets and spreads sufficiently between the brazing material and the Mg-containing aluminum alloy material without disturbing the filling of the brazing material, and the Mg-containing aluminum alloy material is used as the brazing material. Can be joined strongly.

Further, according to the present invention, since the fluoride-based flux can be easily and sufficiently filled in the gap for filling the brazing material, there is an advantage that the brazing operation can be made extremely easy and reliable. is there.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the shape of a brazing filler gap in the present invention in relation to numerical values.
(C) shows another embodiment.

FIG. 2 is a conceptual diagram showing a mode of forming a brazing filler gap in the present invention.

FIG. 3 is a conceptual diagram showing another mode of forming a brazing filler gap in the present invention.

FIG. 4 is a conceptual diagram showing another mode of forming a brazing filler gap according to the present invention.

FIG. 5 is a drawing showing a condenser for a car air conditioner which is an example of an embodiment of the present invention.

6 is a drawing showing a part of the condenser for a car air conditioner of FIG. 5, FIG. 5 (a) is a perspective view showing a configuration of a pipe joint, and FIG. 5 (b) is a sectional view taken along line II.

FIG. 7 is a sectional view showing an arrangement state when the pipe joint member of FIG. 6 is brazed.

FIG. 8 is a cross-sectional view showing a relative position between a brazing ring and a pipe joint member in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 A: base material B: member S: gap for filling with brazing filler metal 1 ... condenser 2 ... flat tube 3 ... inlet side header 4 ... outlet side header 5 ... aluminum corrugated fin 6 ... pipe joint 7 ... brazing ring 7a ... core Material 7b: brazing material 7c: insertion hole 8: pipe joint member 8a: flange 8b: connecting portion 8c: tubular portion t: support portion

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-297139 (JP, A) JP-A-6-63734 (JP, A) JP-A-6-7927 (JP, A) 67985 (JP, U) Hira 1-109368 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 1/19 B23K 1/00 B23K 1/14 B23K 1/18 B23K 33/00

Claims (1)

(57) [Claims] When a brazing material clad with a brazing material is heated and brazed by applying a fluoride-based flux to a surface of a brazing material clad with a brazing material, a gap between the brazing material and the Mg-containing aluminum alloy material is set in advance. .1 to 0.5
mm, characterized in that a gap for brazing filler metal is provided.
Brazing method for aluminum alloy material.