JP3438146B2 - Brazing method of aluminum tube and stainless steel tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to, for example, joining an aluminum pipe of an aluminum heat exchanger to a stainless steel inlet / outlet pipe, joining an aluminum pipe used as a cryogenic piping pipe to a stainless steel pipe, and the like. A brazing method of an aluminum pipe and a stainless steel pipe, more specifically, an aluminum pipe whose outer peripheral surface is coated with a brazing material, and a stainless steel pipe, with the end of the aluminum pipe being inserted into the end of the stainless steel pipe. Regarding how to braze.

In this specification, the term "aluminum" includes aluminum alloy in addition to pure aluminum.

[0003]

2. Description of the Related Art In brazing an aluminum pipe having an outer peripheral surface coated with a brazing material and a stainless steel pipe with the end of the aluminum pipe being inserted into the end of the stainless steel pipe, conventionally, a stainless steel pipe was used. At the end of the tube, a straight tubular expansion part into which the end of the aluminum pipe can be inserted is formed, and the end of the aluminum pipe is inserted into the expansion part of the stainless steel pipe and both pipes are made horizontal. Flux was applied to the both tubes, and both tubes were brazed to each other by heating in a furnace.

[0004]

However, in the case of the conventional brazing method, when the brazing material covering the outer peripheral surface of the aluminum tube melts during heating during brazing, the outer peripheral surface of the aluminum tube and the stainless steel tube The gap between the inner peripheral surface of the expanded section and the inner surface becomes large, and as a result, the aluminum pipe moves slightly downward and the center lines of both pipes are displaced, or the center line of the aluminum pipe is different from the center line of the stainless steel pipe. There was a problem of tilting. Moreover, when the aluminum pipe moves slightly downward and the center lines of both pipes are displaced or the center line of the aluminum pipe is inclined with respect to the center line of the stainless steel pipe, the outer peripheral surface of the aluminum pipe and the expanded portion of the stainless steel pipe are The clearance between the inner peripheral surface and the inner peripheral surface is larger than the other parts in the part including the uppermost part of the entire planned site and including the uppermost part in the circumferential direction, and the molten brazing material remains in this part depending on the capillary phenomenon. After it disappears and flows down, and the molten brazing material resolidifies, the upper part of the fillet existing between the outer peripheral surface of the end of the aluminum pipe and the inner peripheral surface of the expanded portion of the stainless steel pipe becomes smaller, causing brazing failure. There was a problem. Further, in order to suppress the increase in the above-mentioned gap when the brazing material covering the outer peripheral surface of the aluminum pipe is melted as much as possible, the outer diameter of the end portion of the aluminum pipe and the inner diameter of the expanded portion of the stainless steel pipe in the state before brazing It is necessary to make the difference between the two as small as possible, and as a result, it is difficult to insert the stainless steel pipe at the end of the aluminum pipe into the expanded portion of the aluminum pipe, and there is a problem that the setting work for both pipes is extremely troublesome.

An object of the present invention is to provide a brazing method for aluminum pipe and stainless steel pipe which solves the above problems.

[0006]

A method of brazing an aluminum pipe and a stainless steel pipe according to the present invention is an aluminum pipe whose outer peripheral surface is covered with a brazing material, a stainless steel pipe, and an end portion of the aluminum pipe. When brazing the product while inserting it into the end of the stainless steel pipe, form a tapered insertion part that is gradually reduced in diameter toward the tip at the end of the aluminum pipe and at the end of the stainless steel pipe toward the tip. The taper-shaped receiving part, into which the tapered insertion part of the aluminum tube can be fitted ,
Taper angle of outer peripheral surface of tapered insertion part and tapered receiving part
Leave equal to the taper angle of the inner circumferential surface of the further stearate
On the tip of the tapered receiving part of the stainless steel pipe.
Previously formed rare, the spigot of the aluminum tube with plugged received in portion of the stainless steel tube, both tubes vertical form and without such aluminum tube comes upwards, it said brazing both tubes to each other in this state A fillet is formed in the flare .

Aluminum tube and stainless steel according to the present invention
In the brazing method with stainless steel pipe,
Taper angle of outer peripheral surface of pad-shaped insertion part and stainless steel
The taper angle of the inner peripheral surface of the tapered receiving part of the pipe is 3 to
It may be 5 degrees .

Aluminum tube and stainless steel according to the present invention
In the brazing method with steel pipe,
Can be formed at the end of the stainless steel pipe through
There is .

Aluminum tube and stainless steel according to the present invention
Steel pipes and brazed pipes have an outer surface coated with a brazing material.
Luminium tube and stainless steel tube are aluminum tubes
With the end of the plug inserted into the end of the stainless steel pipe,
It is a joint pipe that is attached and the end of the aluminum pipe
The tapered insertion part with the diameter gradually reduced toward the tip.
Is formed at the end of the stainless steel pipe,
Diameter gradually increases and the taper of the aluminum pipe
The taper-shaped receiving portion into which the insertion portion is inserted is formed,
Taper angle of outer peripheral surface of tapered insertion part and tapered receiving part
The taper angle of the inner peripheral surface of the
At the tip of the tapered receiving part of the stainless steel pipe,
Flare is formed and the insertion part of the aluminum tube is stainless steel.
The two pipes are inserted inside the receiving part of the
Formed between the peripheral surface and the inner peripheral surface of the receiving part and in the flare
It is brazed by a fillet .

In the brazing tube according to the present invention, aluminum
The taper angle of the outer peripheral surface of the tapered insertion part of the aluminum pipe, and
And taper angle of inner peripheral surface of stainless steel pipe
May be 3 to 5 degrees, respectively. Also taper
The receiving part is formed on the end of the stainless steel pipe through the step.
May have been .

[0011]

The function of the present invention is to form a tapered insertion portion at the end of the aluminum pipe, the diameter of which is gradually reduced toward the tip, and at the end of the stainless steel pipe, the diameter of which is gradually increased toward the tip and is tapered. Form a tapered receiving part into which the shape insertion part can be inserted, insert the insertion part of the aluminum pipe into the receiving part of the stainless steel pipe, and make both pipes vertical so that the aluminum pipe is above. If both pipes are brazed to each other in this state, the brazing material covering the outer peripheral surface of the aluminum pipe melts during heating during brazing, causing the outer peripheral surface of the insertion part of the aluminum pipe and the receiving part of the stainless steel pipe to Even if there is a gap between the inner peripheral surface and the inner peripheral surface, the aluminum tube slightly moves vertically downward due to its own weight, so that the outer peripheral surface of the insertion portion of the aluminum tube and the stainless steel surface become stainless Gap between the inner peripheral surface of the receiving portion of the steel tube is kept uniformly and small over the entire circumference. Moreover,
The insertion part of the aluminum pipe is tapered with the diameter gradually reduced toward the tip, and the receiving part of the stainless steel pipe is tapered with the diameter gradually expanded toward the tip, so the aluminum pipe moves slightly downward. Even if it does, it is possible to prevent the center lines of both pipes from being deviated from each other and the center line of one pipe from being inclined with respect to the center line of the other pipe. In addition, since the insertion part of the aluminum pipe has a taper shape in which the diameter is gradually reduced toward the tip, and the receiving part of the stainless steel pipe is a taper shape in which the diameter is gradually increased toward the tip, both before brazing Even if the dimension is set so that the outer peripheral surface of the insertion portion and the inner peripheral surface of the receiving portion are in close contact with each other, the insertion portion of the aluminum pipe can be easily inserted into the receiving portion of the stainless steel pipe.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a state before the aluminum pipe and the stainless steel pipe are combined, FIGS. 2 and 3 show a state in which both the pipes are combined, and FIG. 4 shows the outer peripheral surface of the aluminum pipe due to heating during brazing. A state in which the brazing material is melted is shown.

In FIG. 1, an aluminum pipe (1) is an electric resistance welded pipe formed by using an aluminum clad plate whose one surface is coated with a brazing material, the outer peripheral surface of which is coated with the brazing material (2). There is. The brazing material (2) has a thickness of aluminum tube (1)
The thickness of the brazing filler metal (2) is about 0.15 mm when the thickness of the aluminum pipe (1) is 1.5 mm. Then, first, at the end of the aluminum tube (1), a tapered insertion part (3) having a diameter gradually reduced toward the tip is formed.

On the other hand, at the end of the stainless steel pipe (4), a step
A tapered receiving portion (6) is formed in which the diameter is gradually increased toward the tip through the (5) and the tapered insertion portion (3) of the aluminum tube (1) can be fitted therein. The taper angle of the inner peripheral surface of the receiving part (6) is equal to the taper angle of the outer peripheral surface of the insertion part (3) of the aluminum tube (1), and is preferably about 3 to 5 degrees. In addition, the length of the inner peripheral surface of the receiving part (6) is
While keeping the length of the outer peripheral surface of the insertion part (3) of (1) almost equal, set the large end diameter and the small end diameter of the inner peripheral surface of the receiving part (6) to the outer peripheral surface of the insertion part (3). It should be slightly smaller than the large end diameter and the small end diameter. A flare (7) is formed at the tip of the receiving portion (6).

Next, as shown in FIGS. 2 and 3, the insertion portion (3) of the aluminum pipe (1) is inserted into the receiving portion (6) of the stainless steel pipe (4) so that they are concentric with each other. Put in. At this time, there is a slight gap between the tip of the insertion part (3) and the step part (5), and the base end part of the insertion part (3) is slightly outside the receiving part (6). positioned.

Then, the aluminum pipe (1) and the stainless steel pipe (4) are vertically formed by an appropriate jig so that the aluminum pipe (1) is located above, and in this state, the fluoride flux or tin is used. Both tubes (1) and (4) are brazed to each other by applying the added fluoride-based flux and heating it in a furnace. Then, the brazing filler metal (2) covering the outer peripheral surface of the aluminum pipe (1) is melted during heating during brazing, and the outer peripheral surface of the insertion portion (3) and the inner peripheral surface of the receiving portion (6) are separated from each other. The interval becomes large. However, the insertion part (3) and the receiving part (6)
Since the taper is tapered, the aluminum pipe (1) moves vertically downward as shown in FIG. 4, and the center lines of both pipes (1) and (4) are displaced or the center lines of one pipe are Tilt with respect to the center line of the other tube is prevented. Moreover, the gap between the outer peripheral surface of the insertion portion (3) and the inner peripheral surface of the receiving portion (6) is uniform and small over the entire circumference (about 0.1 mm or less).
Therefore, the molten brazing filler metal (2A) stays in the gap due to the capillary phenomenon. When the brazing material (2) in the portion of the aluminum pipe (1) existing outside the receiving portion (6) is melted, it flows down and accumulates in the flare (7). After the molten brazing filler metal (2A) is solidified again, flare (7) is formed between the outer peripheral surface of the insertion part (3) of the aluminum pipe (1) and the inner peripheral surface of the receiving part (6) of the stainless steel pipe (4). Fillets of uniform size are formed in the entire circumference.

[0018]

According to the method of the present invention, as described above, when the brazing material covering the outer peripheral surface of the aluminum tube is melted during heating of the brazing, the outer peripheral surface of the insertion portion of the aluminum tube is melted. Even if there is a gap between the aluminum pipe and the inner surface of the receiving part of the stainless steel pipe, the aluminum pipe slightly moves vertically downward due to its own weight, so that the outer peripheral surface of the insertion part of the aluminum pipe and the receiving part of the stainless steel pipe Since the clearance between the inner peripheral surface and the inner circumference is kept uniform and small over the entire circumference, the molten brazing material stays in the above clearance due to the capillary phenomenon. Therefore, after the molten brazing material is re-solidified, a fillet of a uniform size is formed over the entire circumference between the outer peripheral surface of the insertion portion of the aluminum pipe and the inner peripheral surface of the receiving portion of the stainless steel pipe. It is possible to prevent defective brazing between the stainless steel pipe and the pipe. Moreover, it is possible to prevent the center lines of the brazed pipes from being displaced from each other and the center line of one pipe from being inclined with respect to the center line of the other pipe. Further, since the insertion portion of the aluminum pipe can be easily inserted into the receiving portion of the stainless steel pipe, the setting work before brazing becomes easy.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a state before combining an aluminum pipe and a stainless steel pipe.

FIG. 2 is a partially cutaway front view showing a state in which an aluminum pipe and a stainless steel pipe are combined.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is a partially enlarged vertical cross-sectional view showing a state where the brazing material on the outer peripheral surface of the aluminum tube is melted by heating during brazing.

[Explanation of symbols]

(1) Aluminum pipe (2) Brazing material (3) Insert (4) Stainless steel pipe (5) Step (6) Receiving (7) Flare

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23K 1/18 B23K 33/00

Claims (6)

(57) [Claims] 1. An end portion of an aluminum pipe for brazing an aluminum pipe whose outer peripheral surface is coated with a brazing material and a stainless steel pipe in a state where the end portion of the aluminum pipe is inserted into the end portion of the stainless steel pipe. A tapered insertion part that is gradually reduced in diameter toward the tip, and a taper insertion part that is gradually expanded in diameter toward the tip and can be fitted into the end of the stainless steel pipe. The taper receiving part is formed, and the taper insertion part's outer peripheral surface
The taper angle and the taper angle of the inner peripheral surface of the tapered receiving part, etc.
Well, and the tapered receiving part of the stainless steel pipe
A flared flare is formed at the tip of the, the insertion part of the aluminum pipe is inserted into the receiving part of the stainless steel pipe, and both pipes are made vertical so that the aluminum pipe is above, and in this state and brazing both tubes to each other, frame
(A) A brazing method for an aluminum pipe and a stainless steel pipe, which comprises forming a fillet in the pipe. 2. An outer circumference of a tapered insertion portion of an aluminum tube
Taper angle of surface and tapered receiver of stainless steel pipe
The taper angle of the inner peripheral surface of the part is 3 to 5 degrees, respectively.
Brazing of aluminum pipe and stainless steel pipe described in 1.
Law . 3. A taper-shaped receiving portion is provided with a step through a stainless steel sheet.
3. The method according to claim 1, which is formed at the end of the stainless steel pipe.
Brazing method of aluminum pipe and stainless steel pipe . 4. Aluminium whose outer peripheral surface is coated with a brazing material.
Aluminum tube and the end of the aluminum tube
Brazed in the end of the stainless steel pipe
It is a joint pipe consisting of an aluminum pipe with an end
A tapered insertion part with a gradually reduced diameter is formed.
At the end of the stainless steel pipe,
The diameter is gradually increased and the aluminum tube is tapered
The taper-shaped receiving part into which the
Taper angle of outer peripheral surface of recessed portion and inner peripheral surface of tapered receiving portion
Taper angle is equal to
A flared flare is formed on the tip of the tapered receiving part of the steel pipe.
Formed, the insertion part of the aluminum pipe is stainless steel pipe
Is inserted into the receiving part of the
Fillet formed between the inner surface of the rake and the flare
Aluminum tube and stainless steel brazed by
Steel pipe and joint pipe . 5. An outer circumference of a tapered insertion part of an aluminum tube
Taper angle of surface and tapered receiver of stainless steel pipe
The taper angle of the inner peripheral surface of the part is 3 to 5 degrees, respectively.
A joined pipe of the aluminum pipe according to 4 and a stainless steel pipe . 6. The tapered receiving portion is a stainless steel plate with a stepped portion interposed therebetween.
6. The stainless steel pipe is formed at the end of the steel pipe.
Joint pipe of aluminum pipe and stainless steel pipe .