KR20100039043A - Reinforcement material for top ring groove of piston for internal combustion engine in vehicle and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A piston top ring groove reinforcing material for an internal combustion engine and a manufacturing method thereof are provided to reduce total weight and improve the coefficient of thermal expansion and thermal conductivity by manufacturing hypereutectic aluminum. CONSTITUTION: A piston top ring groove reinforcing material(10) for an internal combustion engine consists of Si 7.0~25.0 weight%, Cu 2.0~7.0 weight%, Mg 0.2~2.0 weight%, and remainders such as Al and inevitable impurities. The content of Si of the piston top ring groove reinforcing material for an internal combustion engine is 14.0~25.0 weight%. The size of the primary silicon distributed to the micro-structure of the reinforcing material is 20~50 micron.

Description

Reinforcement material for top ring groove of piston for internal combustion engine in vehicle and manufacturing method

The present invention relates to a piston top ring groove reinforcement for a vehicle internal combustion engine and a method for manufacturing the same, and more particularly, for a vehicle internal combustion engine having a temperature reduction and a light weight of a moving system component through improved thermal conductivity and weight reduction of a piston component for a vehicle internal combustion engine. A piston top ring groove reinforcement and a method of manufacturing the same.

In general, since the piston of the vehicle internal combustion engine is exposed to high load and heat load during engine operation, the piston material is required to have characteristics for fatigue strength, wear resistance, and weight reduction.

The mechanical loads and thermal loads of the pistons during engine operation differ slightly depending on the position of the pistons, among which the top ring grooves of the pistons are not only exposed to high temperatures but also to high wear resistance due to the high mechanical loads of the piston rings during explosion. Measures are required.

Currently, various methods have been applied to strengthen the physical properties of the top ring groove portion subjected to such mechanical / thermal loads.

For example, in the case of diesel engine pistons, Ni-Resist cast iron is applied to the top ring groove and reinforced.In the case of gasoline engines, Ni-Resist cast iron is used as a countermeasure due to high output. There are increasing cases of reinforced applications.

However, when the cast iron reinforcement is applied to the piston as follows, ① weight increase of the piston occurs due to the high specific gravity, ② heat dissipation of the piston is not performed smoothly due to the low thermal conductivity of the cast iron material, and ③ cast iron reinforcement As the difference in physical properties such as the coefficient of thermal expansion between the two different materials and the aluminum piston occurs, there is a possibility of deformation, resulting in a problem of poor adhesion at the bonding interface of different materials.

As shown in FIG. 1, when Ni-Resist cast iron reinforcement is applied to the aluminum piston, aluminum exhibits thermal expansion of 20 to 22 X 10E-6 / ° C, while cast iron reinforcement is about 10 to 12 X 10E-6 / ° C. Because of the difference in thermal expansion of 2 times, as the temperature rises and cools repeatedly in the engine operating environment, a gap is easily generated at the joining interface, and heat transfer is prevented due to such gaps, resulting in overheating of the piston and It causes the failure.

On the other hand, in order to solve the above problems, various methods such as those shown in FIGS. 2A and 2B have recently been proposed. That is, a method of applying special welding to the top ring groove portion as shown in FIG. 2A has been proposed. In the case of Federal Mogul as shown in FIG. 2B, a conventional reinforcement alloy by welding is applied. A technique for improving the wear resistance and welding resistance of the contrast groove has been proposed.

However, the above method has a disadvantage in that high cost is required because a separate additional process must be applied after the manufacture of the piston.

An object of the present invention for solving the above problems, the piston top ring groove reinforcement for vehicle internal combustion engines that can solve the problem of reinforcement of the top ring groove portion of the piston and is capable of reducing the heat conductivity and weight compared to the Ni-Resist reinforcement and its manufacture To provide a way.

Piston top ring groove reinforcing material for a vehicle internal combustion engine according to an embodiment of the present invention for achieving the above object is 7.0 to 25.0wt% Si; 2.0 to 7.0 wt% Cu; 0.2 to 2.0 wt% Mg; And remainder Al and unavoidable impurities.

According to an embodiment of the present invention, the size of the primary silicon distributed in the microstructure of the reinforcing material is 20 to 50㎛.

Method for producing a piston top ring groove reinforcement for a vehicle internal combustion engine according to an embodiment of the present invention, 7.0 to 25.0wt% Si, 2.0 to 7.0wt% Cu, 0.2 to 2.0wt% Mg, balance Al and inevitable The aluminum material is manufactured by continuous casting for pouring molten aluminum alloy made of impurities and continuously solidifying the aluminum material. The aluminum material is secondaryly processed into a reinforcing material shape and then inserted into a piston casting.

According to another embodiment of the present invention, a method for manufacturing a piston top ring groove reinforcement for an internal combustion engine for a vehicle includes: 7.0 to 25.0 wt% Si, 2.0 to 7.0 wt% Cu, 0.2 to 2.0 wt% Mg, balance Al, and A molten aluminum alloy made of unavoidable impurities is injected into a rotating mold and centrifugal force is applied to the molten metal to produce an aluminum material by centrifugal casting in a hollow form, and the aluminum material is second processed into a reinforcement shape to insert the piston during casting. It is characterized by manufacturing.

According to the piston top ring groove reinforcement for a vehicle internal combustion engine according to the present invention as described above and a manufacturing method thereof, the following effects can be obtained.

first. Compared with the conventional Ni-Resist cast iron reinforcement, the specific gravity is small, allowing about 29 g / kg in weight reduction, thereby improving fuel efficiency by reducing the inertial mass of the moving parts.

second. Compared with the conventional Ni-Resist cast iron reinforcement, the thermal conductivity is more than two times, so the temperature of the piston can be reduced during engine operation.

third. Compared to the conventional Ni-Resist cast iron reinforcement, the piston base material and the same material are used, so the difference in thermal expansion coefficient is small, thereby improving the bonding property and deformation characteristics.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the piston top ring groove reinforcement for a vehicle internal combustion engine according to the present invention and a manufacturing method thereof will be described.

Figure 3 is a perspective view showing a reinforcement of the piston top ring groove according to the present invention, Figure 4 is a microstructure photograph showing aluminum according to the Si content of the reinforcement of the piston top ring groove according to the present invention, Figure 5 is a present invention Figure 6 is a microstructure picture of the material produced by the composition of the reinforcement of the piston top ring groove according to the present invention, Figure 6 is a view showing a continuous casting process for producing a reinforcement of the piston top ring groove according to the present invention, Figure 7 FIG. 8 is a view illustrating a centrifugal casting casting process for manufacturing a reinforcement material of a piston top ring groove according to the present invention, and FIG. 8 is a cross-sectional view illustrating a structure in which a reinforcement material of the piston top ring groove is applied to a piston.

As is known, the piston of a vehicle internal combustion engine is a component that is subjected to high mechanical loads and heat loads when the engine is operated. In particular, the top ring groove portion is generally a portion requiring smooth heat dissipation and wear resistance. It is responding to wear resistance through anodizing surface treatment, and moreover, when high load / high temperature such as diesel engine is applied, cast iron insert reinforcement is applied to top ring groove part.

In the present invention, when the conventional cast iron reinforcement is applied to improve the disadvantages of the weight increase and the disadvantages of low thermal conductivity, the thermal conductivity is improved by more than two times compared to the cast iron reinforcement, light weight of about 65% as shown in FIG. The reinforcement 10 was provided.

As the top ring groove reinforcing material, an aluminum alloy, in particular, an over-process silicon aluminum alloy has been applied in consideration of the need for thermal conductivity and wear resistance required for piston parts.

The reinforcing material 10 of the aluminum alloy is composed of 7.0 to 25.0 wt% Si, 2.0 to 7.0 wt% Cu, 0.2 to 2.0 wt% Mg, and balance Al and unavoidable impurities.

In particular, it is preferable that the eutectic silicon aluminum alloy is applied as the reinforcing material 10, so that the content of Si contained therein is 14.0 to 25.0 wt%.

The reason for limitation of each component contained in the aluminum alloy of the reinforcing material 10 is as follows.

1) Silicon (Si)

The Si improves castability during casting of the aluminum alloy and is dissolved in it to increase the strength of the base metal.

If the content of Si is less than 7.0wt%, it does not provide sufficient strength and castability to the reinforcing material 10, so that it does not correspond to mechanical loads and causes problems in casting, and when more than 25wt%, the strength is too high to cause brittleness. Since destruction due to overload due to engine operation can easily occur, its content was limited to 7.0 to 25 wt%.

In addition, the material of the reinforcing material 10 according to the present invention used aluminum over eutectic silicon alloy as a basic composition.

In general, the alloy for casting aluminum includes Si as a main element for improving castability, wherein it is classified into sub-process, process and over-process according to the content of Si, and the microstructure of aluminum for them is shown in FIG. As shown.

In particular, in the case of the over-process composition, Si is crystallized as a primary in the form of particles during solidification, thereby improving the wear resistance of the part.

2) Copper (Cu)

Cu plays a role of improving the hardenability as a precipitation hardening element. In the present invention steel, Cu is limited to a range of 2.0 to 7.0 wt% in order to obtain a desirable effect of Cu.

3) Magnesium (Mg)

Mg is characterized by excellent thermal conductivity. Especially, Mg has the largest specific strength (low intensity per unit weight) and low specific gravity.

Therefore, its content was limited to a range of 0.2 to 2.0 wt% so as to be dissolved in an aluminum alloy and applied to the appropriate thermal conductivity and light weight as the reinforcing material 10.

And, the microstructure of the over-process in the alloy composition of the reinforcing material 10 is as shown in Figure 5, the size of the primary silicon distributed in the microstructure was in the range of 20 to 50㎛.

Looking at the manufacturing method of the reinforcing material 10 made of the above composition briefly as follows.

First, while manufacturing the material by steelmaking through the melting furnace while adjusting the amount of the component to be added to the aluminum alloy steel for the reinforcing material 10, centrifugal casting is used as a continuous casting or another method.

The continuous casting is an advantageous casting method for making a long good quality casting of a certain cross section, as shown in Figure 6, while pouring molten aluminum alloy consisting of the alloying components as described above while simultaneously solidifying the product How to make

In the centrifugal casting, as shown in FIG. 7, the hollow aluminum alloy made of the alloying components is injected while rotating the mold to apply a centrifugal force to the molten metal, thereby obtaining a casting having good quality in the hollow form. It is a way.

Therefore, it is possible to facilitate casting of the reinforcing material alloy according to the present invention by the continuous casting or centrifugal casting as described above.

The primary raw material manufactured by the continuous casting or centrifugal casting process is subjected to final secondary machining into an insert shape as shown in FIG. 8.

At the time of casting the final product piston (1) it is to cast the piston by setting the reinforcing material (10) produced in the casting mold of the top ring groove position.

Through this process, it is possible to manufacture the piston 1 in which the top ring groove is reinforced by the reinforcing material 10.

That is, by using the reinforcement 10 manufactured as described above as an insert in the casting of the piston 1, it is possible to manufacture at low cost for the reason why the piston 1 with the top ring groove reinforced as a final product can be manufactured.

In addition, since the interface between the reinforcing material 10 and the piston 1 has an interface of aluminum-aluminum, unlike the conventional interface of cast iron-aluminum, the bonding property is good and the deformation characteristics are improved due to the small difference in the coefficient of thermal expansion. The thermal conductivity also has the advantage of being superior to the prior art.

When the Ni-Resist cast iron reinforcing material, which is currently used at about 45g level, is replaced with the reinforcing material 10 according to the present invention, the weight is 16g, and a weight reduction of about 29g / piece per piston (1) is possible. Is about 2.1 times better.

Example

A test comparing the physical properties of the aluminum alloy reinforcement prepared in accordance with an embodiment of the present invention and the conventional cast iron-based reinforcement was done, the results are shown in Table 1 below.

division reinforcement Base material division Conventional Steel Invention steel Basic system Ni-based cast iron Hypereutectic Aluminum Al-Si-Cu-Mg Alloy Hypereutectic Aluminum Al-Si-Cu-Ni-Mg Alloy Component (wt%) C: 2.0 Si: 4.0-6.0 Mn: 0.5-1.5 Ni: 34.0-36.0 Cr: 1.5-2.5 Fe: Balance Si: 14.0-25.0 Cu: 2.0-7.0 Mg: 0.2-2.0 Al: remainder Si: 11.0-13.0 Cu: 1.0-4.0 Ni: 1.0-3.0 Mg: 0.5-1.5 Al: remainder Coefficient of Thermal Expansion (X10E-6) 10-12 18-19 20-22 Thermal Conductivity (W / mK) 46 143 155 Weight (g) 45 16 -

As shown in Table 1, the conventional Ni-based cast iron and the over-processed aluminum according to the embodiment of the present invention and the physical properties were measured for them, the reinforcement of the present invention has a coefficient of thermal expansion and thermal conductivity than the conventional reinforcement It was much higher, while it was found to be very light in weight.

In addition, the conventional reinforcing material has a lot of differences in physical properties compared to the base material, but in the reinforcing material of the present invention is maintained at almost the same level, it is judged that there is no large gap between each other, it is excellent in the bonding interface.

As a result, in the case of a diesel engine using the reinforcement of the present invention it is possible to improve the thermal conductivity and light weight, especially when applied to gasoline engines according to the high output and downsizing development environment according to GDI (gasoline direct injection) and turbo-GDI It can be seen that it is possible to cope with an improvement in the durability of the piston.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation in the scope of the appended claims. It will be understood by those skilled in the art that various modifications may be made and equivalents may be resorted to without departing from the scope of the appended claims.

1 is a view showing a reinforcement of a conventional piston top ring groove.

Figure 2a and 2b is a view showing a reinforcement method of a conventional piston top ring groove.

Figure 3 is a perspective view of the reinforcement of the piston top ring groove according to the present invention.

Figure 4 is a microstructure photograph showing the aluminum according to the Si content of the reinforcement of the piston top ring groove according to the present invention.

Figure 5 is a microstructure photograph of the material produced by the composition of the reinforcement of the piston top ring groove according to the present invention.

Figure 6 is a view showing a continuous casting process for producing a reinforcement of the piston top ring groove according to the present invention.

Figure 7 is a view showing a centrifugal casting process for producing a reinforcement of the piston top ring groove according to the present invention.

Figure 8 is a cross-sectional view showing a structure for applying a reinforcement of the piston top ring groove according to the present invention to the piston.

* Brief description of symbols for the main parts of the drawings *

1: piston 10: reinforcement

Claims (6)

7.0 to 25.0 wt% Si; 2.0 to 7.0 wt% Cu; 0.2 to 2.0 wt% Mg; And A piston top ring groove reinforcement for an internal combustion engine of a vehicle, comprising a balance Al and inevitable impurities. The piston top ring groove reinforcement for an internal combustion engine of claim 1, wherein the Si content is 14.0 to 25.0 wt%. The piston top ring groove reinforcement for an internal combustion engine of claim 1, wherein the size of the primary silicon distributed in the microstructure of the reinforcement is 20 to 50 μm. By continuous casting to melt and continuously solidify a molten aluminum alloy composed of 7.0 to 25.0 wt% Si, 2.0 to 7.0 wt% Cu, 0.2 to 2.0 wt% Mg, balance Al and unavoidable impurities A method for producing a piston top ring groove reinforcement for an internal combustion engine of a vehicle, characterized by producing an aluminum material. Centrifugal force is applied to the molten aluminum by injecting a molten aluminum alloy composed of 7.0 to 25.0 wt% Si, 2.0 to 7.0 wt% Cu, 0.2 to 2.0 wt% Mg, balance Al and unavoidable impurities into a rotating mold. A method of manufacturing a piston top ring groove reinforcement for an internal combustion engine in a vehicle, characterized by producing an aluminum material by centrifugal casting in a hollow form. The method of claim 4 or 5, wherein the reinforcing material is manufactured by inserting the aluminum material into the reinforcing material in the form of a secondary machining piston and inserting the piston top ring groove reinforcing material for a vehicle internal combustion engine.

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