DE2018615A1 - Method for soldering the heat sinks of motor vehicle radiators - Google Patents

Description

^: ■ PATENTANWÄLTE '. MUNICH 2
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8000 Munich 2 April 17, 1970 case 5671/60953 - T 3592

Fabrica de Radiatoare si Cabluri Brasov Brasov / Romania

Method for soldering the heat sinks of automobile radiators

The invention relates to a method for soldering the heat sinks of motor vehicle radiators.

There are known methods for soldering the heat sinks of car coolers, after which the heat sinks from previously pickled and - with an easily fusible alloy covered cooling tubes on which. Copper, brass or steel ribs were applied, in electrical or with liquid or

_o . gaseous fuel heated stoves is introduced, wherein

co '*

00 the connection between ribs and pipes through the melting

⁰¹ zen of the easily fusible alloy takes place.

fo The known processes have the disadvantages

that the heating of the entire structure for the purpose of melting

the easily fusible alloy is not evenly achieved can lead to the formation of spots of incomplete soldering can lead, which affects the heat transfer during operation of the cooler to a great extent. The usage of Pickling agents, in most cases based on zinc chloride solutions lead to the etching of the furnace, which adversely affects the quality of the soldering, and damage to the im further technological process to be soldered surfaces, which is why complex neutralization measures after soldering required are. Nevertheless, the remains of the dressing agent not completely removed from the surface of the heat sink, so that this continues the etching process and the service life shorten the cooler.

Furthermore, methods for the production of motor vehicle radiators are known, according to which the cooling fins are made of aluminum. In this case, one applies for connecting the aluminum ribs with the covered with a fusible alloy cooling pipes to be joined aluminum fins with a solderable with low-melting alloy metal layer to the electrochemical or mechanical plating, as the direct soldering of the Aluminiims is difficult because of Alumini umoxy ds chi CHT _r the removal of which requires a number of complex operations, which is the main disadvantage of this method.

109815/1102

Another disadvantage is that the soldering work in furnaces with a neutral atmosphere in the presence of corrosive Pickling happens, which is difficult to remove from the contact surface.

By the method according to the invention, these

Avoid disadvantages by using a hot pickling bath when soldering -

is used, which consists of 98% mineral oil and 2% pickling mixture based on ammonium bromide, ammonia and glycerine. In this bath, the heat sink, which is made up of tubes with attached copper, brass, steel or aluminum fins, is inserted after the aluminum fins have been pickled and covered with a protective layer, and the cooling tubes with one or two layers of easily fusible alloy and a protective layer were provided, wherein the heat sink in the pickling bath 5 to 10 minutes (| remains at 260 ° to 300 ⁰ C. During this time, the pickling, melting of the fusible alloy and the brazing takes place, after which the soldered heat sink in a horizontal position through. Air jet and washed with an appropriate common solvent.

The invention is carried out by the following exemplary embodiments explained in more detail. "

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example 1

Invention device requires the soldering of the aluminum produced cooling fins with the cooling tubes remove the oxide layer covering the fin surfaces. For this purpose, the aluminum fins are immersed in a bath for 1 to 5 minutes at 20 ° to 30 ° C Pickling solution pickled with the following percentage composition: 40% techh. Nitric acid, spec. Weight = 1.40, 2% hydrofluoric acid a 38% concentration and 58% water. The ribs are then washed in a running water bath for 1 minute and then at 30 for 30 seconds to protect the stain immersed in a protective bath up to 35 ° C, which consists of 5 to 15% stearin, 2% ammonium bromide and 83 to 93% techn. alcohol consists. In this way, a protective layer is created on the rib surfaces, the thickness of which is between 2 and 4 u, which prevents re-oxidation of the pickled ribs.

The cooling pipes are made by a conventional thermal process with a thickness of at least 0.04 to 0.06 mm Layer of easily fusible alloy covered, which has the following composition: 46% tin, 15% zinc, 15% Cad- ' mium, 24% lead, or with two successive layers of solder alloy, the first layer of which is a common alloy of 40% tin and 60% lead, and the second an easily fusible alloy of the composition: 51% tin, 16.2% zinc

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16/2% is cadmium, 16.6% is lead. The cooling pipes are then protected by immersion in a stearic protective solution with the composition given above.

The aluminum fins treated in the manner described above are placed on the tubes prepared in this way, then the heat sink is placed in a hot pickling bath made of 98% mineral oil and 2% pickling additive with the following composition: 60% stearin, 20% ammonium bromide, 10% glycerin and 10% concentrated ammonia solution immersed »The mineral oil used for this purpose must have the following characteristics: 0.910 rel. Density at 20 ° C, color ünio Maxima -5, flash point according to Marcuson 265 ° C, freezing point -4 ° C max., Kinematic toughness according to CST228 to 224 at 50 C and 26 at 100 ° C, conventional toughness at 50 ° C: 30 ° to 32 ° E, viscosity number 85, water content: none, ash content 0.01 max., - mineral acid and alkalinity - not available% , Conradson coke 1.4%.

The heat sink is in this bath for 5 to 10 minutes, Depending on size and design, leave at 260 ° to 280 ° C. While During this time, the alloy melts and the aluminum fins are soldered onto the cooling tubes.

After removing it from the hot pickling bath, the heat sink cooled in a horizontal position by air jet, whereby

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the cooling and solidification of the solder alloy at the bond points, as well as draining and recovery the warning pickling liquid is carried out.

The complete cleaning of the heat sink is accomplished by immersion in a bath, which is an appropriate contains common solvent.

The soldered heat sink is then used for assembly, according to the technological plan.

Example 2

Cooling fins made of copper, brass or steel mounted on cooling tubes, which previously had a layer of solder the composition; 40% tin and 60% lead, as indicated in Example 1, as well as a protective coating by immersion in a protective solution of 20% stearin, 40% paraffin oil, 18% paraffin, 2% ammonium bromide and 20% gas oil.

The subsequently assembled heat sink is inserted into a hot pickling bath for the purpose of soldering was given in Example 1. In this bath, the heat sink remains at 260 ° bis for 2 to 10 minutes 300 C. During this period, the pickling of the surfaces takes place, the melting of the low-melting ends on the cooling tubes Alloy and the soldering of said ribs

1098115/1 702 '. '

instead of. .

After removal from the hot pickling bath, the soldered construction is treated further as in Example 1.

By using the method according to the invention
is the soldering of unclad aluminum to the
Cooling tubes achieved and unnecessary the furnaces with neutral
Atmosphere that were previously required for soldering and the
are expensive and difficult to maintain by using immersion baths with a hot pickling liquid in their place, which at the same time ensure the pickling of the surfaces to be soldered and the uniform heating up to the melting temperature of the alloy on the cooling tubes, whereby the soldering without the occurrence of oxidation points or zones is erzieJLt to the tubes, wherein no more corrosive mordant are required for soldering, which are difficult to remove from the surface of the heat sink%.

109815/1702

Claims (6)

Claims 1.y method for soldering the heat sink of motor vehicle radiators, characterized in that the heat sink built in a known manner from cooling tubes with applied copper, brass, steel or aluminum fins in a hot pickling bath made of 98% mineral oil and 2% pickling mixture of ammonium bromide, Ammonia and glycerine are immersed, whereby the aluminum fins are preferably previously pickled and covered with a protective layer, and the cooling tubes with one or two layers of easily fusible alloy and a protective layer, and the heat sink prepared in this way for 6 to 10 minutes in the 260 ° to 300 ⁰ C heated Wambeizbad is left for the purpose of pickling, melting the easily fusible alloy and soldering the ribs to the cooling tubes, after which the soldered heat sink is cooled in a horizontal position by means of an air jet and washed with a customary appropriate solvent. 2. The method according to claim 1, characterized in that a pickling mixture of 60% stearin, 20% ammonium bromide, 10% glycerin and 10% concentrated ammonia solution are used. 3, method according to one of the preceding claims, characterized in that for the purpose of pickling the aluminum 1 0 9 8 1 '5/1 7 0 2 rip a bath from 40% techn. Nitric acid, spec. Weight = 1.4, 2% hydrofluoric acid, 38% concentration, the remainder being water, is used, in which the pickling is carried out at 20 ° to 30 ° C. for 1 to 5 minutes. 4. The method according to any one of the preceding claims, characterized in that after pickling the aluminum ribs in a bath of 5 to 15% stearin, 2% ammonium bromide and 83 to 93% techn. Hold alcohol at 30 ° to 35 ° C for 30 seconds to create a protective membrane. 5. The method according to any one of the preceding claims, characterized in that the cooling tubes are easily meltable with a layer by conventional thermal processes Alloy that is at least 0.04 mm thick and consists of 46% tin, 15% zinc, 15% cadmium, 23% lead, or with two back (J. Covered one above the other to be applied solder alloy layers, the first from a 40% tin and 60% lead conventional solder alloy, and the second from a light fusible alloy of: 51% tin, 16.2% zinc, 16> 2% cadmium, 16.2% lead or with just one layer of 40% tin and 60% lead alloy. 6. The method according to any one of the preceding claims, characterized in that the cooling tubes after application of the solder alloy or alloys in the case of copper, brass or steel ribs in a 20% stearin / 40% faraffin oil, - 1 0981 S / 1702 "■ ■ ■ ' 18% paraffin, 2% Ainmoni umb roraid and 20% gas oil, and in the case the aluminum ribs in a from 5 to 15% stearin, 2% ammonium bromide and 83 to 93% techn. Alcohol existing bath Immerse for 30 seconds at 30 ° to 35 ° C to form a protective membrane. 10981S / 1702