KR0138932B1 - Plastic method of aluminium alloy piston ring groove by plazma arc welding - Google Patents

Abstract

The present invention melts and fuses a copper metal powder with a base material of a piece barrel into a plasma arc in a portion of a top ring groove of an aluminum alloy piece barrel, so that an alloy layer of a fine intermetallic compound is uniformly distributed to provide a top ring groove having excellent wear resistance. The present invention relates to a method of forming a piston ring groove by forming a plasma arc growth hardening, wherein a plasma torch is placed at a position of an aluminum alloy piston top ring groove, and the metal powder 44 is supplied into the plasma arc around the piston. Plasma arc growth hardening process to fuse the molten metal and powder molten metal of the piston to form the alloy layer 20: a cutting process for forming a top ring groove 30 in the alloy layer.

Description

Forming method of aluminum alloy piston ring groove by plasma arc growth hardening

1 is an overall schematic view of a piston by the molding method of the present invention

FIG. 2 is an enlarged sectional view of the portion A in FIG. 1

Figure 3 is an exemplary view showing the growth of the piston top ring groove portion of the present invention by the plasma arc

4 is an enlarged cross-sectional view of main parts of the plasma torch portion of the present invention;

(A), (b), (c) are enlarged sectional views of the principal part which show the example of shaping | molding of the piston top ring groove by the plasma arc growth hardening of this invention.

6 (a), (b), and (c) are photographs showing the microstructure of the alloying, boundary and piston portions of the present invention.

* Explanation of symbols for main parts of the drawings

10: top ring groove portion 20: alloy layer

30: top ring groove 40: power supply

41 electrode 42 plasma gas

43: atmosphere gas 44: rapid powder

45: plasma arc 46: coolant

50: plasma torch portion 100: piston

The present invention relates to a growth-hardening method for piston ring grooves by plasma arc melt alloying which can form ring grooves on which top rings are mounted in an aluminum alloy piston for an engine into an alloy layer having excellent heat and abrasion resistance. Plasma arc growth hardening that can mix and alloy the molten metal of the piston and the molten metal of the feed powder in an appropriate ratio by supplying metal powder into the plasma arc while partially melting the top ring groove portion using a plasma arc to the piston top ring groove portion. It relates to a molding method of the piston ring groove by the.

In general, the piston reciprocating in the cylinder of the engine gives a rotational force to the crankshaft through the connecting rod to the high-pressure, high-pressure gas pressure received by the expansion stroke by the combustion of the compressed fuel.

At this time, the piston head is exposed to the combustion gas of 200 ° C. or more, and at the same time, it receives a pressure of 40 to 60 kgf / cm 2 in a short time and also reciprocates the cylinder at a high speed, so that a strong friction occurs between the cylinder walls.

Therefore, since the piston is fully responsible for its function under the above bad conditions, the following conditions are required.

First, it is possible to effectively use the pressure of the explosion gas in the cylinder, and there should be no gas leakage under any temperature condition.

Second, there should be a gap for proper lubrication to reduce friction with the cylinder walls and to minimize mechanical losses.

Third, the oil lubricating the cylinder wall should not penetrate into the combustion chamber.

Fourth, the thermal conductivity must be good enough to prevent the material's strength from dropping due to heat or abnormal combustion due to redness.

Fifth, since the highway reciprocating motion in the cylinder to reduce the power loss due to the inertia and other requirements are required to be easy to facilitate the satisfactory compliance.

It is currently used, which means that the piston material of an automobile engine must be resistant to wear and have high strength, and it is also a lightweight material because it requires considerable force to overcome inertia in the process of moving in the opposite direction after stopping completely at the top dead center or bottom dead center. Alloy (AC8A) is mainly used.

However, aluminum material is lighter than cast iron, but its heat resistance and abrasion resistance are remarkably poor, so that the cracks at the edges of the piston and wear of the top ring groove due to the high temperature and high pressure conditions of the combustion chamber in the engine and the reciprocating motion of the piston easily occur. Have

In order to solve such problems, cast iron nickel-resist is manufactured as a method of improving the aluminum alloy piston currently used, inserted into a piston mold, and manufactured through a casting process to improve wear resistance.

However, in this case, since the cast iron is used, the total weight of the piston is increased, the adhesive strength with aluminum is reduced, and the design temperature is limited due to the temperature rise of the piston.

That is, the position of the top ring groove for reducing the combustion chamber dead volume and the position of the hole in the design of the piston for the cooling structure are limited in that the cooling efficiency is increased.

In order to solve this problem, instead of cast iron nickel-resist, an example of a composite reinforced piston of fiber reinforced metal (FRM) or nickel foaming agent can be found.

However, such a method has a problem in that the piston shape is restricted because the high pressure casting method should be used.

As another method, a method of locally forming a wear resistant alloy layer in a top ring groove using an electron beam is known.

In other words, the groove is machined at the position of the top ring groove of the piston, the copper wire is wound into the groove, and the copper wire and the surrounding base material are melted by electron beam elongation in the evolved state to diffuse copper.

The method rotates the piston while melting the part passing through the beam to solidify, thereby forming an alloy layer in which the intermetallic compound of aluminum and copper is finely and uniformly distributed. To form.

However, in forming the alloy layer at the position of the top ring groove by the electron beam, after processing the groove at the position of the top ring groove, the technical problem of projecting the electron beam by mounting a copper wire in the groove and the electron beam can be applied to the piston. Since it must be made in a vacuum at the time, there are technical problems such as equipment cost including the equipment to maintain the vacuum and time required to maintain the vacuum.

The present invention is to solve the above problems, while heating the plasma metal to the top ring groove portion of the piston by injecting the copper metal powder into the plasma arc, the base metal of the piston is melted and solidified together to form a fine intermetallic compound and alloying layer It is an object of the present invention to provide a method for forming a piston ring groove by plasma arc growth hardening which can be uniformly distributed in a top ring groove having excellent wear resistance.

In order to achieve the above object, the present invention provides a metal powder that is supplied to a plasma mark at a position of a piston top ring groove made of an aluminum alloy so that the molten metal and the powder molten metal of the piston are fused to the arc to form an alloy layer. Process and a cutting process for forming a top ring groove in the alloy layer, wherein the metal powder is 50 to 200 μm copper (Cu) powder, the addition amount is 10 to 50% by weight, and the alloy layer is copper ( Cu) and an aluminum (Al) alloying layer.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 3 to 5, the plasma torch 50 is positioned at the piston top ring groove portion 10 made of aluminum (AC8A), followed by alloy molding while partially melting the base material. Part 10 is subjected to a plasma arc used for melting and growth as shown in FIG.

The plasma arc is generally to be supplied with power from the power supply port 40, the torch unit 50 is the plasma gas 42, the cooling water 46, the metal powder 44 and around the electrode 41 The atmospheric gas 53 is supplied to generate the plasma arc 45.

At this time, since the polarity is a direct current positive polarity (DCSP) to use a deep pressure, the plasma gas is argon, the atmospheric gas uses helium (He) and uses a current range of 100 to 200 amperes that can be alloyed.

In addition, the alloying material of the metal powder 44 selects the copper (CU) to increase the wear resistance of the piston.

Copper forms a fine intermetallic compound with aluminum to form a very hard alloy layer, and its distribution is uniform in alloying than other metals.

The size and shape of the powder is a variable of the alloying layer, the size of which is about 50-200 μm, and a spherical shape is used.

The amount of the copper powder to be added is about 10 to 50% by weight, and the addition of excessive copper makes the alloying layer fragile so as not to exceed 50% by weight.

In the growth of the plasma arc, as shown in FIG. 3, the piston 100 body is rotated so that the growth hardening layer 20 is formed by the plasma arc in the top ring groove portion 10 around the perimeter.

As shown in FIG. 5 (b) by the above-mentioned plasma, copper metal powder 44 is supplied to the entire circumference of the top ring groove part in the plasma arc so that the base metal molten metal and powder of the piston 100 itself are supplied by the arc. The molten metal is fused to form an alloy layer 20 of copper (Cu) and aluminum (Al).

The alloyed piston as described above is subjected to the top ring groove 30 processing by the automatic lathe cutting process is the shape is as shown in Figure 5 (c).

Regarding the characteristics of the growth hardening layer of the present invention, as shown in Figs. 6A, 6B, and 6C, the structure of the piston portion, the alloying layer, and its boundary portion, which was not alloyed, was enlarged by 400 times. It was.

As can be seen from the picture, the alloy layer has a uniform intermetallic compound of aluminum and copper, and the bonding of the boundary is also firm.

The hardness of the alloying layer is Hv 150 ~ 300 (depending on the copper content%) 2 ~ 3 times higher than the piston hardness, it can be seen that the wear resistance of the alloying layer is improved by at least 2 times.

As described above, the present invention supplies a metal powder into the plasma arc while partially melting the top ring groove portion by using a plasma arc to the ring groove portion of the piston, so that the molten metal and the feed powder molten metal of the piston can be mixed and alloyed at an appropriate ratio. The piston ring groove formed by the plasma arc growth hardening can be obtained.

In the present invention, the copper metal powder is introduced into the plasma arc while the plasma arc is heated to the top ring groove of the piston to melt and solidify together with the base metal of the piston to form a fine intermetallic compound, which is uniformly distributed in the alloying layer, thereby providing excellent wear resistance. Top ring grooves can be formed and the effect is expected.

Claims (1)

Plasma torch is positioned at the position of the piston top ring groove of the aluminum alloy material so that the plasma lower metal powder 44 containing 10-50% by weight of copper having a size of 50 to 200 µm is supplied to the entire plasma arc. While the groove position of the piston is partially melted, the molten metal and the powdered molten metal are fused to form a copper and aluminum alloy layer 20, and the top ring groove 30 is formed in the alloy layer formed by the above-described hardening and growth hardening process. Forming method of the piston ring groove by the plasma arc growth hardening, characterized in that the mechanical cutting process to form a.