KR20190101028A - Dissimilar material brazing method of aluminum alloy and stainless steel applied to vehicle - Google Patents

Abstract

The present invention relates to a dissimilar material brazing method of an aluminum alloy and stainless steel applied to a vehicle and, more specifically, to a dissimilar material brazing method of an aluminum alloy and stainless steel applied to a vehicle which relates to a characteristic method for joining stainless steel and aluminum applied to a main body and an intake/exhaust system of a vehicle. The method for joining an aluminum alloy and stainless steel in an intake/exhaust system of a vehicle comprises: a washing process of cleaning a surface of the stainless steel and the aluminum alloy; a galvanizing process for a joining portion of the stainless steel; a flux coating process of improving melting of the aluminum alloy by coating flux on a joining portion of the aluminum alloy; a drying process of removing water formed on the flux; and a joining process of bringing the aluminum alloy and the stainless steel into contact with each other to braze the aluminum alloy and the stainless steel.

Description

Dissimilar material brazing method of aluminum alloy and stainless steel applied to vehicle}

The present invention relates to a method for brazing a dissimilar material brazing of aluminum alloy and stainless steel applied to a vehicle, and more particularly, to a vehicle relating to a characteristic method for joining stainless steel and aluminum applied to an engine intake and a body of a vehicle. It relates to a method for brazing dissimilar materials between aluminum alloy and stainless steel.

In general, the weight of a vehicle is considered a very important parameter in terms of the amount of exhaust gas and the improvement of fuel economy. In recent years, in the aspect of reducing environmental pollution and reducing fuel costs, vehicle weight has been reduced, and the necessity of the automobile industry has been greatly demanded by mandatory measures such as regulating the amount of exhaust gas.

In order to achieve a lighter weight of the vehicle, the use of aluminum alloys, which are lighter than conventional steel sheets and have a satisfactory strength and rigidity, are increasing. In the case of engine intake and exhaust machines, oxidation resistance, corrosion resistance and heat resistance are high due to the operating environment at high temperatures. Stainless steel is widely used.

That is, in the part where some stainless steel is applied, the bonding with the aluminum alloy inevitably occurs, but the stainless steel and the aluminum alloy are different from each other and are not joined by welding or brazing.

Conventionally, in the position of the engine intake and exhaust machine, mechanical coupling between aluminum alloy and stainless steel is made to join the heterogeneous materials. Specifically, a method of applying heat-resistant rubber that can withstand the high temperature of the engine intake and exhaust system and enables mechanical coupling of aluminum alloy and stainless steel is used, or a joining method by riveting or pressing is used.

Such mechanical coupling has a problem that the bonding strength is weak compared to the method by welding or brazing, and in particular, in the case of heat-resistant rubber that is used a lot, there is a problem that the durability and the reliability of the bonding force are low and the replacement is frequent.

In addition to the mechanical coupling, there is also a method of joining dissimilar materials using a friction welding, explosion welding, friction stir welding, but there is a problem that can not be widely applied due to geometric constraints, in order to solve these problems Although a method of joining dissimilar materials using a separate mediatored base material has been developed, there is a problem in that workability is very low, such as having to prepare separate mediators and separately bonding them to both sides.

KR 10-1553708 B1 KR 10-1783891 B1

The present invention has been invented to solve the above problems, it is possible to simply combine by special treatment on both sides of the dissimilar material, and also to create an atmosphere that can be smoothly bonded to the dissimilar material to be applied to the vehicle to increase the bonding force The object is to provide a method for brazing dissimilar materials of alloy and stainless steel.

The object of the present invention is not limited to the above-mentioned object, and other objects which are not mentioned will be clearly understood from the following description.

The dissimilar material brazing joining method of the aluminum alloy and stainless steel applied to the vehicle according to the present invention for achieving the above object, in the method of joining the aluminum alloy and stainless steel in the intake and exhaust machine of the vehicle, the surface of the aluminum alloy and the stainless steel Cleaning process to clean; Galvanizing the stainless steel joints; A flux coating process applied to a joint portion of the aluminum alloy to improve melting of the aluminum alloy; A drying process of removing moisture formed in the flux; And a bonding process for brazing the aluminum alloy to the stainless steel.

The present invention by the above configuration can be expected the following effects.

By simplifying the joining of the dissimilar stainless steel and the aluminum alloy, productivity is improved compared to the method of using a mediator base material or joining by mechanical bonding.

Ultimately, due to the improved productivity, it is possible to apply the vehicle omnidirectionally, thereby reducing the weight of the vehicle, and reducing the exhaust gas and improving fuel efficiency.

When the stainless steel and the aluminum alloy are combined, the bonding is smoothed by preheating before brazing by using a laser. In addition, the bead can be widely formed during brazing by flux application on the aluminum alloy side, thereby enabling a firm bonding.

In the case of heat-resistant rubber, rivets, and press-fitted methods, which are conventionally combined by mechanical coupling, the coupling force must be decreased due to corrosion or wear, and thus frequent replacement is required. There was a problem that the operation rate is lowered due to the receipt for replacement, but this problem can be solved by enabling a solid coupling of the stainless steel and the aluminum alloy.

1 is an overall flowchart of a method for brazing dissimilar materials of aluminum alloy and stainless steel applied to a vehicle according to an exemplary embodiment of the present invention.
Figure 2 is a conceptual diagram of the brazing of aluminum alloy and stainless steel according to an embodiment of the present invention.
Figure 3 is a block diagram of the bonding portion of the dissimilar material brazing bonding method of the aluminum alloy and stainless steel applied to a vehicle according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings a method for brazing dissimilar materials of aluminum alloy and stainless steel applied to a vehicle according to a preferred embodiment of the present invention will be described in detail.

1 is a complete flowchart of a method for brazing dissimilar materials of an aluminum alloy and a stainless steel applied to a vehicle according to an exemplary embodiment of the present invention. FIG. 2 is a conceptual view and diagram of a brazing of an aluminum alloy and a stainless steel according to an exemplary embodiment of the present invention. 3 is a block diagram of the joint portion of the dissimilar material brazing bonding method of the aluminum alloy and stainless steel applied to a vehicle according to an embodiment of the present invention.

The dissimilar material brazing bonding method of the aluminum alloy and the stainless steel applied to the vehicle according to the preferred embodiment of the present invention, as shown in Figure 2 washing process (S1), zinc plating process (S2), flux coating process (S3), drying It consists of a process (S4), a preheating process (S5) and a bonding process (S6).

First, look at the washing process (S1).

Washing process (S1) is generally a process for removing dust or dirt, condensate, lubricating oil and oil that can affect this in order to improve the bonding when welding or brazing, such as bonding is performed.

Washing process (S1) is performed according to a general method, preferably performing an ultrasonic pickling (Supersonic pickling) method to wash while giving an ultrasonic vibration, it may be neutralized and rinsed after ultrasonic pickling.

In ultrasonic pickling, the washing agent may be heated to 70 to 90 ° C. to improve the washing power through the activity of the chemical component of the washing agent.

The cleaning process S1 may be performed before the start of the bonding process S6 since the function of the flux may be lowered by the impurities present in the bonding surface at the time of brazing, resulting in incomplete bonding.

Next, look at the zinc plating process (S2).

After the cleaning process (S1), zinc (Zn) may be plated on a part of the joint of stainless steel. Zinc has good reactivity with iron (Fe) or aluminum (Al) and is plated on stainless steel, and later plays a role of mediating the joining of the stainless steel and the aluminum alloy (10) when joining the aluminum alloy (10). Can be.

Zinc plating may be any thing easy depending on the working environment, such as electro zinc plating or hot dip galvanizing.

As described above, since the galvanizing serves to mediate the joining of the stainless steel 20 and the aluminum alloy 10, the plating quality is very important. In particular, the plating thickness is a parameter that affects the bonding quality, the plating thickness to maintain 5 to 10㎛.

Next, look at the flux application process (S3).

Flux creates a thin layer that does not react with the metal surface that melts during welding or brazing, thereby preventing the metal surface from melting by oxidizing by contact with the atmosphere or by containing moisture by contact with water vapor. It does not affect the role.

In general, the flux is applied to the surface of the welding rod in the case of arc welding, and is melted together with the melting of the welding rod during the progress of welding to form an oxide film on the surface of the welding bead. In step S6, since brazing is performed by MIG (Metal inert Gas) or TIG (Tungsten inert Gas), a separate coating process is required for supplying the flux.

If the amount of flux is insufficient, beads may not be formed properly. In detail, the aluminum alloy 10 should be smoothly melted so that the beads should be formed widely. Spots or narrow beads may be formed due to contact with the atmosphere and penetration of water vapor.

Formation of such incomplete beads eventually leads to a decrease in bonding strength, which makes it difficult to achieve the object of the present invention.

Preferably, the amount of flux is used at a concentration of 3 to 8 g / ㎡ uniformly applied to the surface of the junction portion, it is possible to immerse in a flux barrel or to use a spray method, it is preferable to use an aluminum-based flux. Do.

Next, look at the drying process (S4).

Drying process (S4) may be necessary to remove the oil or water that may occur in the flux coating process (S3). As described above, the application of the flux is for the purpose of preventing the penetration of impurities or moisture into the molten metal, so that the flux or the moisture of the flux itself must be removed to function.

Drying process (S4) may be carried out drying for 20 to 30 minutes at a temperature of 90 to 100 ℃. At temperatures above 100 ° C, the boiling point of moisture is exceeded, and even a short time of drying can cause rapid phase change, which can cause porosity and imbalance on the uniform coated surface of the flux. Therefore, drying occurs at high temperatures below the boiling point for a long time. It is preferable.

Next, look at the preheating process (S5).

In general, preheating prior to welding or brazing activates the melting of the base metal, activates the galvanizing or flux as a medium of the above-mentioned bonding, or cracks that may occur when the high temperature is rapidly applied to the low temperature base material. Is made to prevent.

The joining part is heated by a gas torch, the method using a high frequency, the method of laminating | stacking and joining at high temperature, bonding at low temperature, etc. are mainly used.

In the present invention, a method by the laser 30 may be used for preheating. The laser 30 generally has a property of light having a straightness, so that accurate irradiation is possible at a desired position.

However, in the present invention, when intensive preheating is performed by the laser 30 on the junction, rather than the purpose of preheating for the activation of the junction, thermal stress may be induced in the base material, thus intentionally defocusing. Blur) so that the laser 30 is irradiated to a large area. In detail, when the laser beam 30 is focused, the width is 20-30 μm. However, in the present invention, the laser beam 30 may be defocused so as to have a width of 3 mm to 5 mm.

As the power source of the laser 30 used in the present invention, a capacitance of 1 to 2 kHz is used, and the solid-state laser 30 having a continuous wavelength rather than a pulse wave can be used. In the present invention, as the preheating of the bonding portion prior to the brazing of the bonding process (S6) to play the role of the laser 30 to be described later, the wettability of the zinc plating and aluminum alloy 10 of the stainless steel 20 is improved by preheating To facilitate bonding.

Finally, look at the bonding process (S6).

For the bonding process (S6) it may be specifically formed a shape of the butt portion of the stainless steel 20 and the aluminum alloy (10).

Specifically, the end of the aluminum alloy 10 of the butt portion of the stainless steel 20 and the aluminum alloy 10 forms a step, so that the end of the stainless steel 20 can be seated on the step. have.

The aluminum alloy 10 has a melting point of 600 to 650 ° C., and the stainless steel 20 has a melting point of 1,400 to 1,450 ° C. When welding or brazing is used when joining two metals, melting of the aluminum alloy 10 having a low melting point is prevented. In order for the stainless steel 20 to be joined by the molten metal 50 formed therethrough, the stainless steel 20 is formed at the end of the aluminum alloy 10 so as to be joined.

The joining can be made by the brazing method, which is a joining method for the low melting point of the aluminum alloy 10, but the melting point is low and easy to deform, shrinkage deformation or deterioration during brazing depending on the properties of the thin aluminum alloy (10). MIG or TIG method can be used which is small and applicable to sheet metal.

In detail, after the end of the stainless steel 20 is seated at the end of the stepped aluminum alloy 10, the preheating process S5 by the laser 30 precedes the direction in which the bonding process S6 proceeds. It can be done by.

The torch 40 is positioned so that the brazing, which is the joining process S6, may be performed after the preheating process S5 is performed, and the upper step 11 of the aluminum alloy 10 having a low melting point is While molten, the molten metal 50 may be formed on the upper portion of the stainless steel 20 on the lower step 13.

As described above, since the surface of the stainless steel 20 is galvanized by the galvanizing process (S2), the aluminum alloy 10 and the stainless steel 20 may be formed by the covalent bonding of zinc and aluminum. It can be a junction.

At this time, the flux applied to the aluminum alloy 10 by the flux application process (S3) is dissolved by brazing by the torch 40 to form a thin film on the surface of the molten metal 50, the molten metal 50 ) Improves the bonding quality by avoiding contact with air and water vapor.

The above embodiments are merely exemplary, and those having ordinary skill in the art may have other embodiments modified in various ways.

Therefore, the true technical protection scope of the present invention should include not only the above embodiment but also various other embodiments modified by the technical spirit of the invention described in the claims below.

S1: cleaning process
S2: Zinc Plating Process
S3: flux coating process
S4: drying process
S5: Preheating Process
S6: Bonding Process
10: aluminum alloy
11: upper step
13: lower step
20: stainless steel
30: laser
40: torch
50: molten metal

Claims (5)

In the method of joining aluminum alloy and stainless steel in the intake and exhaust machine of a vehicle,
A cleaning process for cleaning the surfaces of the aluminum alloy and the stainless steel;
Galvanizing the stainless steel joints;
A flux coating process applied to a joint portion of the aluminum alloy to improve melting of the aluminum alloy;
A drying process of removing moisture formed in the flux; And
The brazing method for dissimilar materials brazing the aluminum alloy and stainless steel applied to the vehicle consisting of a bonding process for brazing the aluminum alloy and the stainless steel. The method of claim 1,
Dissimilar brazing bonding method of the aluminum alloy and stainless steel applied to the vehicle, characterized in that further comprising a preheating process using a laser between the drying process and the bonding process. The method of claim 2,
The preheating process is a method for brazing dissimilar materials of aluminum alloy and stainless steel applied to a vehicle, wherein a large area is preheated by defocusing a focus of a laser. The method of claim 1,
The drying process is a different material brazing bonding method of the aluminum alloy and stainless steel applied to the vehicle, characterized in that carried out for 20 to 30 minutes at a temperature of 90 to 100 ℃. The method of claim 1,
The bonding process is a different material brazing bonding method of the aluminum alloy and stainless steel applied to the vehicle, characterized in that for brazing MIG or TIG.

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