KR101954955B1 - The Process for Repairing Ex-Mani by Brazing - Google Patents

Abstract

The present invention relates to a joining method of an Ex-Mani for a vehicle, in which joining portions and turbine housings through which exhaust gases are joined and joined are joined by an induction brazing method using a copper-based alloy applicator and a high-frequency induction coil, A fatigue strength of a joint portion is relaxed, and bonding defects such as thermal deformation, spatter, crack, or back bead are prevented.
More specifically, the present invention relates to an exhaust manifold (EX-MANI) including a merging section and a turbine housing for merging exhaust gases of a vehicle engine into a single passageway and exhausting the exhaust gas, wherein the merging section and the turbine housing The high frequency induction coil being spaced apart from the high frequency induction coil; Applying or applying a filler metal on the joining portion of the merging portion and the turbine housing; And heating the high frequency induction coil to melt the filler material. The present invention also provides a method of joining an Exmani using brazing.

Description

[0001] The present invention relates to a method of joining Exmani using brazing,

The present invention relates to a joining method of an Ex-Mani for a vehicle, in which joining portions and turbine housings through which exhaust gases are joined and joined are joined by an induction brazing method using a copper-based alloy applicator and a high-frequency induction coil, A fatigue strength of a joint portion is relaxed, and bonding defects such as thermal deformation, spatter, crack, or back bead are prevented.

Recently, the development of the turbo GDI engine has been actively pursued in response to the regulation of exhaust gas for vehicles, the demand for improvement of fuel efficiency, and the trend of downsizing of the engine.

In order to improve the output of the turbo GDI engine, the efficiency of the engine is increased by exposing it to a high temperature (eg, 950 ° C. or higher) and a high pressure in comparison with the existing MPI and GDI engines. To ensure durability against such severe conditions The Exmani runner and the confluent part are made of a thick and strong cast steel material, ie Ex-Mani, which is a cast-steel integral type.

Such cast steel materials are excellent in durability but they are heavy and have a disadvantage in that the heat-transfer efficiency to the catalyst is disadvantageous and the catalyst off-time (LOT) during the initial start-up is somewhat long. .

Under such circumstances, a double tube type excavator of plate type is recently emerging as one of the methods for attaining weight reduction and reduction of emission in the turbo GDI engine.

Referring to FIGS. 1A and 1B, in the case of the air gap extruder, an inner runner portion 110 and an outer runner portion 120 for forming an assembly between the extraneous manifold and the turbine housing, and a turbine housing (MAG) is generally performed, the welded portion is the most vulnerable portion subjected to severe thermal fatigue and vibration of 950 DEG C, and the fracture occurs in the thermal cycling and vibration endurance evaluation And this occurs on the welding portion of the merging portion 130.

In addition, when arc welding is performed, the base material is heated to the melting point and then cooled, so that thermal stress may be generated by melting, and breakage may occur at the interface between the welded portion and the base material due to tensile residual stress (90 ~ 110 °), and it is vulnerable to fatigue stress.

In addition, when the amount of heat input is excessively large, back beads are generated, resulting in the problem that the spark plug causes the merchantability to deteriorate.

Therefore, there is a demand for a junction method of the Exmani that can solve these problems.

It is an object of the present invention to provide a joining method of an exmani which is improved in durability by improving the fatigue strength at the joining portion of the joining portion and the turbine housing by using an induction brazing method other than the conventional arc welding method.

It is another object of the present invention to prevent junction defects such as cracks and back beads and to suppress thermal deformation and spatter generation at the junction regions to improve junction quality and merchantability.

Further, according to the present invention, another object of the present invention is to provide a method of joining Exmani, which facilitates process control by a small process variable in preparation for conventional arc welding.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the conventional art described above, and it is an object of the present invention to provide an EX-MANI which includes a merging portion and a turbine housing for merging exhaust gases of a vehicle engine into a single passage, Mounting the high frequency induction coil on the outer side of the joining portion of the joining portion and the turbine housing; Applying or applying a filler metal on the joining portion of the merging portion and the turbine housing; And heating the high frequency induction coil to melt the filler material. The present invention also provides a method of joining an Exmani using brazing.

In the present invention, the above-mentioned filler is preferably a copper (Cu) alloy filler.

In the present invention, the copper (Cu) based alloy filler comprises 8.0 to 12.0% by weight of manganese (Mn), 2.0 to 6.0% by weight of nickel (Ni) and 1.0 to 3.0% by weight of silicon (Si) .

In the present invention, the heating temperature of the high frequency induction coil is preferably in the range of 900 to 1000 ° C.

In the present invention, the heating of the high frequency induction coil is preferably performed at an output of 3 to 10 kW for 50 to 100 seconds.

In the present invention, it is preferable that the above-mentioned Exmani is a double-pipe type air gap expansive.

According to the joining method of the Exmani using the brazing according to the present invention, since the joining angle of the joint portion is made larger than that of the arc welding, the fatigue strength at the joining portion of the Exmani junction portion / turbine housing is advantageous in terms of stress concentration with respect to the load (Arc welding: more than 1590 ° C, brazing: about 1150 ° C), the fatigue strength in the heat affected zone is improved and the durability of Exmani is improved There is an effect to be improved.

Further, according to the present invention, as in arc welding, there is no problem such as torch angle interference, and there is little probability of occurrence of defective junctions such as cracks and back beads, and there is no thermal deformation or spatter, thereby improving junction quality and merchantability .

Further, according to the present invention, since only the current and the output time applied to the high frequency induction coil need to be considered in comparison with the arc welding in which the current, voltage, speed, torch angle, protective gas condition, welding rod type, There are few variables and it is easy to control the process conditions.

Figs. 1A to 1B are diagrams of a configuration of an automotive extemany. Fig.
Fig. 2 is an exemplary view showing an arc welding process according to the prior art; Fig.
FIG. 3A is an exemplary view showing a joining portion of a conventional extemal manifold and a turbine housing joined together by arc welding; FIG.
FIG. 3B is an exemplary view showing a joining portion of the automotive extruder and a turbine housing joined together by a brazing method according to an embodiment of the present invention. FIG.
4A is an SEM image showing a welding angle of a base material in arc welding according to the prior art.
FIG. 4B is a SEM image showing the joining angle of the spark plug in the brazing method according to an embodiment of the present invention. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

The present invention relates to a new joining process for increasing durability in a gasoline turbo engine and is designed to improve fatigue strength against high temperature compared to conventional arc welding. The induction brazing method is proposed in order to improve thermal deformation and fatigue strength deterioration caused by conventional arc welding when joining the junction 130 of the Exmani and the turbine housing 140.

Brazing refers to a technique of joining two base metals after heat is applied by using a filler metal without damaging the base metal at a melting point or less. When the base metal is melted or melted, It can be applied to various industries such as automobiles, aircrafts, electric and electronic devices and the like, since various kinds of joining are possible, whether they are homogeneous or heterogeneous metals, without damaging the base material. The advantages of such a brazing method are as follows.

First, since it is possible to form various kinds of junctions between homogeneous metals and dissimilar metals, the material cost can be reduced, the degree of freedom of shape can be guaranteed, and various parts can be designed.

Secondly, it is possible to have a relatively strong bonding strength than other bonding methods, and in some cases, the tensile strength of the bonding part is made stronger than that of the base metal.

Third, since it is possible to form elaborate joints and to obtain a clean joint after brazing, it is not necessary to add additional mechanical machining such as grinding or streaking.

Fourth, since the joint is a metal metallurgical joint, characteristics such as ductility, impact resistance, vibration proof, airtightness, thermal conductivity, and corrosion resistance are superior to those of other joints.

Hereinafter, characteristics of the present invention will be described in consideration of the advantages of the brazing method.

Figs. 1A to 1B are diagrams showing a configuration of an automotive extemany.

The exhaust gas from the vehicle engine is connected to the exhaust pipe through an inner runner 110 having a plurality of branch pipes. The inner runner 110 is covered by the outer runner 120 in the form of a plate, A plurality of branch pipes are connected to the exhaust pipe through a single passage.

Accordingly, the inner runner 110 and the outer runner 120 having a plurality of branches are connected to the exhaust pipe through the merging portion 130. As described above, the double runner type air gap Generally, the exhaust manifold 140 includes a turbine housing 140 for connecting the confluence portion 130 of the manifold made of cast iron and the exhaust pipe of the cast steel.

Therefore, in the present invention, with respect to the method of joining the confluence portion 130 of cast iron and the turbine housing 140 of the cast steel to bond the different kinds of metals with each other easily, fatigue strength is improved, The joining portion 130 and the turbine housing 140 are joined together by a brazing method.

FIG. 2 is an exemplary view showing arc welding according to the prior art, and FIG. 3A is an exemplary view showing a joining part of a merging part and a turbine housing of a conventional automobile extinner by arc welding.

Conventionally, joining of the confluence portion 310 and the turbine housing 320 is performed through arc welding (MAG) in order to manufacture an assembly between the Exmani and the turbine housing. The welded joints have a small joining angle (90 ~ 90 °), and the welded joints have a small joint angle, 110 °) and is vulnerable to fatigue stress.

In addition, back beads and spatter may be generated due to incidence of excessive heat, resulting in nonuniform bonding surfaces, resulting in deterioration of merchantability.

FIG. 3B is an exemplary view illustrating a joining portion of the automotive extruder and a turbine housing according to an embodiment of the present invention joined together by a brazing method.

According to the joining method of the Exmani using the brazing of the present invention, the high-frequency induction coil 350 is separated from the joining portion of the joining portion 310 and the turbine housing 320 and then mounted.

The high frequency induction coil 350 may be disposed by determining a distance from the bonding site in consideration of a rated current or the like, and may be formed using a known coil material.

In addition, the high frequency induction coil 350 may be formed in various polygonal shapes such as a circular shape and a quadrangular shape so as to cover the outer periphery of the joint portion, and may be provided in a linear shape parallel to the needs of the invention.

When the high frequency induction coil 350 is mounted, it is possible to preheat the joining portion of the merging portion 310 and the turbine housing 320 according to the necessity of the invention, .

Subsequently, a step of applying a filler metal onto the joining portion of the merging portion and the turbine housing is performed.

As shown in the following Table 1, it is preferable that the filler material 340 is made of a copper (Cu) alloy alloying material, and the copper (Cu) To 12.0 wt%, nickel (Ni) 2.0 to 6.0 wt%, and silicon (Si) 1.0 to 3.0 wt%.

The copper (Cu) is included as a main element for strengthening the strength and corrosion resistance. The copper (Cu) alloy alloying material is generally advantageous in manufacturing cost compared with the nickel (Ni) alloy used at high temperature.

The silicon (Si) is added so as to lower the melting point of the solvent, and is an effective element for improving the high-temperature oxidation characteristics as the amount of the silicon (Si) added increases. It also plays an important role in high temperature strength and grain growth resistance. It is an element which has a considerable effect in suppressing intergranular corrosion cracking (SCC). In addition, it can be said that it plays an important role in securing the brazing strength by forming a predetermined compound together with Ni contained in the filler.

The nickel (Ni) serves to further increase the post-brazing strength without significant loss in thermal conductivity, and serves to assist the filler 340 to reach the desired balance between strength, thermal conductivity and corrosion resistance after brazing .

Such a copper (Cu) based alloy filler may be formed into various shapes such as wire, wire, plate, special shape, paste, and the like.

Then, when the high-frequency induction coil is heated to melt the filler, the joining of the joining portion and the turbine housing is completed.

In the present invention, the heating temperature of the high frequency induction coil 350 may be in the range of 900 to 1000 ° C, and the heating time may be preferably in the range of 3 to 10 kW for 50 to 100 seconds.

The present invention can be applied to the boundary region between the runner merging portion 310 and the turbine housing 320 by applying the high frequency induction coil 350 and applying or applying the copper alloy alloy filler material 340, The filler material 340 melted by the capillary action is diffused and welded between the runner merging portion 310 and the turbine housing 320.

At this time, the property indicating the degree of affinity between the confluence portion 310 and the turbine housing 320 and the filler material 340 can be expressed by wetting, and the flow between the joint portions 310 and the jointing gap 340 The phenomenon is a capillary action.

That is, the main basic principle of brazing is that when the joining is performed by adding a filler to the base material, the filler material 340 is melted into the base material by wetting and flows into the base material by capillary phenomenon.

Table 2 below shows the fatigue strength of the single piece using the induction brazing and the conventional arc welding using the high frequency induction heating of the present invention in which the fatigue strength was greatly improved as described above.

As can be seen from Table 2, it can be seen that the fatigue strength of the brazing according to the present invention was improved about 1.5 times higher than that of arc welding under two conditions of high temperature, and the turbocharger gas temperature was 950 ° C (metal temperature was about 900 ° C) It can be confirmed that the fatigue strength in the heat affected zone is improved.

FIG. 4A is an SEM image showing the joining angle of the base material in the arc welding according to the related art, and FIG. 4B is an SEM image showing the joining angle of the spark plug in the brazing method according to an embodiment of the present invention.

As shown in FIG. 4A, in the case of arc welding, the joining angle 410 is small, so that the joining portion acts as a notch of stress concentration and the fatigue strength is weak. On the other hand, referring to FIG. 4B, It can be confirmed that the angle 420 is large and the stress concentration is relaxed to increase the fatigue strength.

Although the present invention has been described in connection with the specific embodiments of the present invention, it is to be understood that the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Various modifications and variations are possible.

110: Inner runner section
120: outer runner section
130, 310:
140, 320: Turbine housing
210: wire
220: Protective gas
230: arc
240: base metal
330: welding torch
340: Ingredient
350: high frequency induction coil
410, 420: joint angle

Claims (7)

1. A jointing method for an excavation using brazing to join a joining portion of an air gap excavator and a turbine housing in place of an arc welding method,
Mounting the high frequency induction coil on the outer side of the joining portion of the merging portion and the turbine housing;
(Cu) containing 8.0 to 12.0 wt% of manganese (Mn), 2.0 to 6.0 wt% of nickel (Ni), 1.0 to 3.0 wt% of silicon (Si) and the balance of copper (Cu) on the junction of the merging portion and the turbine housing Cu) alloy alloy filler metal (Filler Metal); And
And heating the high frequency induction coil to deposit the copper (Cu) alloy alloy material,
Wherein the joining angle of the joining portion is larger than that of the arc welding.
The method according to claim 1,
And the temperature of the combined joining portion and the turbine housing is lower than that in arc welding.
delete The method according to claim 1, wherein the temperature of the brazing is 1010 to 1050 占 폚.
The induction heating apparatus according to claim 1, wherein the heating of the high-
And heating at an output of 3 to 10 kW for 50 to 100 seconds (sec).
In a single unit which is joined to a confluence portion of an air gapexmaney and a turbine housing by brazing,
The joining portion of the joining portion and the turbine housing is made of copper (Cu) containing 8.0 to 12.0 wt% of manganese (Mn), 2.0 to 6.0 wt% of nickel (Ni), 1.0 to 3.0 wt% of silicon (Si) ) Based alloy filler metal (Filler Metal)
Wherein the single piece has a fatigue strength of from 160 MPa to 125 MPa at 700 to 900 ° C.

In a single unit which is joined to a confluence portion of an air gapexmaney and a turbine housing by brazing,
The joining portion of the joining portion and the turbine housing is made of copper (Cu) containing 8.0 to 12.0 wt% of manganese (Mn), 2.0 to 6.0 wt% of nickel (Ni), 1.0 to 3.0 wt% of silicon (Si) ) Based alloy filler metal (Filler Metal)
Wherein the single unit can be used even when the temperature of the turbocharger gas is 950 DEG C or higher.

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