JPS6092069A - Multihole tube for aluminum heat exchanger and its production - Google Patents

Abstract

PURPOSE:To prevent buckling of an extruded multihole tube consisting of Al or Al alloy having the m.p. of a specific temp. or above in the stage of vacuum brazing even if a thinner walled fin is used by coating a specifically composed Al-Si alloy brazing filler metal on the surface of said tube. CONSTITUTION:A flux is coated on the surface of an extruded multihole tube consisting of Al or Al alloy having >=640 deg.C m.p. The tube is then dipped for 2-60sec into a molten bath of the brazing filler metal of Al-6-13%Si alloy kept at <=630 deg.C. The alloy of Al-6-13%Si is thus hot dipped on the surface of the tube.

Description

[Detailed Description of the Invention] The present invention relates to a multi-hole tube for an aluminum heat exchange core that is assembled by a waxing method, and a method for manufacturing the same.
In particular, it has made it possible to reduce the weight and cost of the heat exchanger.

Generally, aluminum heat exchangers, such as condensers and evaporators, have multiple holes (1) as shown in Figure 1.
a) A flat extruded multi-hole tube (1
) is bent into a meandering shape as shown in Figure 2, a corrugated fin (2) consisting of a brazing seam (1) is placed between each duplex (1), and flux is applied.
A heat exchanger core is used that is waxed at a temperature of around 00°C.

In this specification, all indications of component composition % of A (or 8) alloy materials mean % by weight.

Conventionally, the extruder hole duplex was JIS1050 (purity 99).
．． Pure △J) of 5% or more, J l51100 (AJ!
-0.05~0.20% Cu), J I 8300
3 (to A i -0,05・0.20% CIJ -1
,0-1,5%Mn), J[83203(A,e
-1.0 to 1.5% M1)) etc., and J
133003.3203 or 6951 (A f -0
,20~0.50%5i-0,15~0.4%Cu-
0.40~0.8+)% tvlu> as the core material, and on both sides Aλ-8i alloy brazing filler metal, for example IJJ IS 43
43 (△, f)-4,5~6.0%Si), JI
S4045 (A f!, -9.0~11.0%Si
), J I 54047 (A, (-11,0 to 13.0
A plating sheet with a thickness of about 0.1 (imm) coated with %S1) or the like is used.

In recent years, heat exchanger I9 has been used from the standpoint of energy saving and cost reduction.
! There is a desire to reduce the weight of the fins, and the first step is to consider making the fins thinner.
Brazing at around 0°C sometimes causes the fins to buckle, making it extremely difficult to reduce the weight of the heat exchanger core.

In view of this, the present invention was developed as a result of various examinations.
The buckling of the fin occurs because 3i in the brazing seam 1 diffuses into the core material, reducing the C strength, and the absolute thickness of the core material without diffusion becomes thinner, reducing the strength. Furthermore, as a result of the study, it was possible to use bare fins without coating the brazing material, and it was possible to reduce the heat exchanger's j 'l to I + ¥ A and the cost. We have developed a multi-hole duplex for aluminum heat exchangers that can be folded down and a method for manufacturing it.

That is, as shown in FIG. 3, the present invention provides a 3i alloy brazing filler metal (3i alloy with a melting point of 640° C. or higher) on the surface of an extruded multi-hole tube made of an alloy (1) having a melting point of 640° C. or higher. ).

In addition, the production method of the present invention has a melting point of 640°C or higher.
Apply flux to the surface of an extruded multi-hole tube made of alloy (1j), and apply flux to 63
The tube is characterized by being immersed in a molten bath at 0° C. or lower for 2 to 60 seconds to form a hot-dip plating layer of the wax on the surface of the tube.

In the present invention, the melting point of the extruded multi-hole china is 640°C.
The reason for the above limitation is that Af-6 has a melting point of less than 640°C.
~13%Si alloy braze is difficult to hot dip plate, and A (or A (alloy) with a melting point of 640°C or higher, for example,
．． 3203 etc. are used. Also, on the surface of the tube A (
-6~13% The reason for covering the 3i alloy braze is to use bare fin material that is not coated with brazing material, such as Jl 33003.
This is to enable brazing in combination with a fin material made of 3203.6951 etc., and the S
The reason why the i content is limited as above is that the 3i content is 6%.
This is because even if it is less than 13%, or if it exceeds 13%, the melting point of the brazing material will become high, making hot-dip plating and brazing difficult. If it is necessary to improve the fluidity and wettability of the brazing material, one or more of Bi, 3N, Pb, and Sr may be added within a range of 0.3% or less. good.

In the present invention, the surface of an extruded multi-hole boob is coated with wax, and the wax is coated by hot-dip plating.
Flux is used to avoid forming a good plating layer since the duplex and brazing filler metal are well suited.

Fluxes include KCI, Na cz, C*,
Ordinary wax (114
: Using a chloride or fluoride flux for J, apply it to the surface of the tencoup in advance and immerse it in a molten bath of brazing material. It is desirable to degrease and clean the duplex surface with a solvent, detergent, etc. prior to applying flux. Therefore, the temperature of the molten bath of brazing filler metal in hot-dip plating is set to 630°C.
℃ or less and soak it! Limiting the time to 2・-60 seconds, I
This is to ensure good immersion plating, and the bath temperature is 6.
If the temperature exceeds 30°C, part of the multi-hole tube will deform or melt; if the immersion time is less than 2 seconds, the plating will be incomplete even if the tube is preheated; if it exceeds 60 seconds, the plating will be 3i diffuses deeply into the interior from the boot-1 surface,
This is because the melting of the surface layer of the wax (=J 4:J II;

In this way, the present invention has a multi-hole duplex whose surface is coated with -L solder, which can be combined with bare fins without using the fins made of plastic wire coated with wax on both sides, and which can be combined with ordinary wax. (=J 4: Since the heat exchanger core can be obtained by the J method, there is no need to coat both sides of the fins with brazing metal, so brazing does not cause any deterioration in the strength of the fins, and therefore reduces the thickness of the fins.) becomes possible,
This makes it possible to reduce the weight and cost of the heat exchanger.

The present invention will be described in detail below with reference to Examples.

Using an extruded multi-hole tube of the shape shown in Fig. 1 made by a conventional method and an AZ-S:alloy braze shown in Table 1, the tube surface was degreased with a detergent and then KC(, Na (1! , L
i C1, l i Apply a 50% aqueous solution of flux for "normal brazing 1" containing F3 as one component 15, 30
Drying and preheating were performed at a temperature of 0° C. for 1 minute, and brazing filler metal was dip-plated on the duplex surface under various conditions. While observing the plating state of these, the tube was bent into a serpentine shape as shown in Figure 2, and was mated with a bare corrugated fin made of JIS 3'003 with a thickness of 0.12 mm. T! , KCf, NaC (, Li Cf, LiF3
The above-mentioned wax (41, J flux 50
% aqueous solution, dried at 300°C for 10 minutes, heated to 610°C for 10 minutes to wax, to create a heat exchanger core and braze it. investigated gender. These results are listed in Table 1.

In addition, regarding the brazing C property, the bond between dupe and fin is 1
Those that could not be soldered were judged as unacceptable, those that had parts that were not waxed or that did not form a uniform fillet were judged as poor, and those that had perfect waxiness were judged as good.

1st person Dicove No., tube brazing filler metal composition (%
) Material Melting point ('C) Si AJ! flux
Temperature 1α (T inventive tube I JISi050 approx. 6
46 6.5 Remainder Right 62;2 9 Ijl It
[11! 3 12 n 60t 491161! 5 763 (8J I 83003 approx. 643 u 161:9 A
J! -0,3% C11 approx. 648〃1110A, f! -0
,3%Cu approx. 645uII-0,3%1yln Comparison tube 14 JIS1050 approx. 646 9
lI TsugB61:12 6.5 u stone 64 +3 5 n 62 14 15 l162 1591! !・61 6 Plating condition Plating condition Wax (dtJ
) Time (seconds) Appearance Average plating S1 diffusion Scraping thickness μ) Depth μ) 10 Uniform 30 4 Good 2 012 030 + 4020 51 Metered -- Impossible 2 Tube -- Partly melted) 50 Large unevenness 5020 Defective i 2 60 5 1 Mostly -- Not plating 70 Partially 3070 Defective Melting As is clear from Table 1, A with a melting temperature of 640°C or higher,
AJ extruded multi-hole tube made of Q or Yabu alloy! -6
2 in a molten bath of ~13% Si alloy brazing material at 630℃ or less
Melt the brazing material on the tube surface by dipping for ~60 seconds.
The tubes (No, 1 to 10) of the present invention, which are plated in a good condition, have a good plating condition, and as shown in FIG.
) is also 2
It can be seen that it is shallow at ~30μ and has excellent brazing properties of the heat exchanger core.

On the other hand, even if dupe and brazing filler metal are within the scope of the present invention,
Comparative tube No. 11, which does not use flux, cannot be plated with brazing filler metal on the surface of the tube, and comparative tube No. 12, whose plating quality exceeds 630°C.
In this case, a part of the duplex will melt, and the plating time will be reduced by 2.
Comparative tube No. 1, H+, where the plating time was less than 60 seconds, was hardly plated, and no irreversibility was observed. In comparison tube No. 16, where the plating time exceeded 60 seconds, the duplex was partially dissolved. The solderability was also poor, and the depth of Si diffusion 11) in the plating brazing material in the duplex was as deep as 70μ, as shown in FIG. 4(b). In addition, comparison tube No. 0013 contains the least amount of 3i and comparison tube No. 1 contains the most amount of 3i.
It can be seen that in No. 4, even if the intermediate conditions were within the range of the present invention, the plating condition was poor and the brazing properties were also poor.

In addition, all brazed heat exchanger cores comply with JIS 30.
Even though relatively thin corrugated fins of 0.12 m in thickness were used, no buckling of the fins was observed.

For comparison, an extruded tube made of JI33003 shown in Fig. 1 was used, the brazing filler metal was bent into a serpentine shape without dip-plating, and Δ(-11% 3i alloy solder was applied to both sides of the core H made of JIS3003). A brazing seam 1~ (16 μm of brazing filler metal per side) with a thickness of 0.1 Gmm coated with 10% per side. A conventional heat exchanger core was created by combining Korgu 1 to fins with a thickness of 12μ) as shown in Fig. 2 and brazing them under the same conditions as in the above example, and the bondability of the tubes and fins was determined. We investigated the buckling properties of the fins.As a result, we found that the buckling properties were good, but the
．． In the case where s+ fins were used, buckling occurred in the fins.

In this way, according to the tube of the present invention, it is possible to create a heat exchanger core using bare fins that do not cover the wax shank, and even if the fins are made thinner, buckling during vacuum waxing can be prevented. This has the remarkable effect of making it possible to reduce the weight and loss of the heat exchanger.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of an extruded multi-hole tube f for a heat exchanger, FIG. 2 is a perspective view showing an example of a heat exchanger core, and FIG.
The figure is a perspective view showing an example of a multi-hole duplex according to the present invention, and FIG.
A) and ([]) are enlarged cross-sections of the main parts of the multi-hole duel 1 covered with a wax shrine;
indicates a multi-hole duplex for comparison. 1 Extruded multi-hole tube 1a hole 2 Corrugated fin 3 Brazing material Figure 1 Figure 2 Figure 3 Figure 4 (A) (0)

Claims (2)

[Claims] (1) A (-6 to 13% 3i
Multi-hole tube for aluminum heat exchanger 1° characterized by coating with alloy brazing material (2) By applying 7 lux to the surface of an extruded multi-hole tube made of A (or A (alloy) with a melting point of 640°C or higher,
- Made of aluminum characterized by being immersed in a molten bath of 6 to 13% 3i alloy solder at 630°C or lower for 2 to 60 seconds, and melting the brazing material on the surface of the die. Method for manufacturing multi-hole tube 7 for heat exchanger.