KR101277120B1 - Manufacturing method of forged piston - Google Patents

Abstract

The present invention relates to a method for manufacturing a forged piston including a head portion and a skirt portion, the method comprising the steps of manufacturing a predetermined alloy cut piece for forming the skirt portion and a predetermined alloy powder for forming the head portion; And a sintering step of forming a preform by injecting the cut piece and the powder into a mold, applying heat and pressure to diffusely bond the cut piece and the powder, and forging the preform. The piece and the powder relates to a forging piston manufacturing method characterized in that the heterogeneous material different in formability and strength and heat resistance, according to the present invention, while using a high-strength material excellent in high temperature properties, it is possible to manufacture a piston excellent in forging formation have.

Description

Forging Piston Manufacturing Method {MANUFACTURING METHOD OF FORGED PISTON}

The present invention relates to a forged piston manufacturing method, and relates to a forged piston manufacturing method that can satisfy both high temperature properties and forging formation.

In general, a piston for reciprocating at high speed is installed in a cylinder of an engine of an internal combustion engine such as an automobile, and the piston receives a high temperature and high pressure combustion gas generated in a combustion chamber to rotate a crank shaft through a connecting rod.

In this way, the piston is driven under severe conditions such that the piston head is exposed to high-temperature combustion gas, is subjected to high pressure shocks, and large friction is generated by the high-speed reciprocating motion in the cylinder.

Therefore, the piston should be made of a material that is not only light and durable, but also has good thermal conductivity and heat resistance.

In particular, recently developed automotive engines are combined with increased combustion pressure, increased power, and reduced weight in order to achieve fuel efficiency and environmental regulations. High temperature fatigue strength, ii) good high temperature tensile and yield strength, iii) low coefficient of thermal expansion and density, and iv) lightweight design.

In this regard, the casting method of the manufacturing method of the piston is a method of injecting the molten alloy into the mold to form a shape and then cooled and processed, whereby there is a problem that the durability of the material due to the lack of air bubbles or compactness of the parts due to lack of durability There is. On the other hand, by using the forging method that presses the press with high pressure to make the piston, the coarse material is changed finely and finely by high pressure and plastic deformation, which makes it possible to manufacture a piston with smooth surface and excellent durability. have.

However, in general, a material having excellent high temperature properties has a problem that it is difficult to form forging because it is difficult to deform at a high temperature.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a forged piston manufacturing method excellent in forging formation while using a high-strength material having excellent high temperature properties.

The present invention as a means for solving the above problems,

A method of manufacturing a forged piston comprising a head portion and a skirt portion (hereinafter comprising a pin boss portion), the method comprising the steps of: manufacturing a predetermined alloy cut piece for forming the skirt portion; Preparing a predetermined alloy powder for forming the head portion; A sintering step of forming a preform by injecting the cut pieces and the powder into a predetermined mold and applying heat and pressure to diffusely bond the cut pieces and the powder; And forging the preform; wherein the cut piece and the powder are heterogeneous materials having different formability, strength, and heat resistance.

Here, the cut pieces may be formed of an alloy having a higher moldability than the powder, and the powder may be formed of an alloy having a higher strength and higher heat resistance of the cut pieces.

Here, the step of manufacturing the cut piece, the step of preparing a skirt ingot to be a raw material of the cut piece; Dissolving and alloying the skirt ingot to produce a billet through a continuous casting method; And cutting the billet to form the cut pieces.

The preparing of the powder may include preparing a head ingot to be a raw material of the powder; And dissolving the head ingot to produce the powder by rapid cooling and solidification (atomization).

Here, the skirt ingot may be Al, Si, Ni, Cu and Mg as a component composition, the Si ratio may be characterized in that 10 to 13% by weight.

Herein, the head ingot has a Si composition of 12-17 wt%, a Fe ratio of 4.5-5.5 wt%, a Cu ratio of 1.5-2.5 wt%, and a Mg ratio of 0.5-1.5 wt%, with the remainder being Al. It can be characterized in that filled with.

Here, the Zr ratio in the head ingot may be 0.1 to 1.5% by weight is added and the Al ratio may be characterized in that reduced to a corresponding ratio.

Here, the Ni ratio in the mixture may be characterized in that 0.1 to 1.5% by weight is added and the Al ratio is reduced to the corresponding ratio.

Here, the step of cutting and surface treatment after the step of forging the preform; it may be characterized in that it further comprises.

According to the method for manufacturing a forged piston according to the present invention, the head portion of the piston is formed of a material that can withstand a high temperature environment well, the material of the skirt portion is formed of a material having excellent formability, thereby facilitating forging processing and high temperature environment Edo is able to produce a piston that can withstand well.

In addition, according to the present invention does not have to go through the step of forming a separate billet using the alloy powder to form the head portion has the effect of reducing the work time and cost.

In addition, according to the present invention has a high temperature tensile strength, high temperature fatigue strength and hardness, the thermal expansion coefficient and specific gravity has the effect of forming a lower piston head portion.

1 is a flow chart showing the flow of the forged piston manufacturing method according to the present invention,
Figure 2 is a flow chart representing the flow of the manufacturing method of FIG.
3 is a sectional view showing a piston manufactured according to the manufacturing method of FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in this specification and claims should not be construed in a common or dictionary sense, and the inventors will be required to properly define the concepts of terms in order to best describe their invention. Based on the principle that it can, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various equivalents may be substituted for them at the time of the present application. It should be understood that there may be water and variations.

1 is a flow chart showing a schematic flow of the forged piston manufacturing method according to the invention, Figure 2 is a flow chart showing the flow of the forged piston manufacturing method according to the present invention, Figure 3 is a forged piston production of the present invention A cross section showing a piston manufactured according to the method.

As shown in FIGS. 1 to 3, a method of manufacturing a forged piston according to an embodiment of the present invention includes manufacturing a predetermined alloy cut piece 100 to form a skirt portion 420 of a piston. (S10) and manufacturing a predetermined alloy powder 200 to form a head (410) of the piston (S20) and the cutting piece 100 and the powder 200 in a predetermined mold Forging the preform 300 and the sintering step S30 of forming the preform 300 by diffusion bonding the cut piece 100 and the powder 200 by applying heat and pressure thereto ( S40) and the forged preform 300 may be configured to include a machining step (S50) for cutting and surface treatment.

Meanwhile, in the case of the present invention, the skirt portion 420 of the piston also includes the pin boss portion 430 of the piston.

First, the present invention forms a predetermined alloy cutting piece 100 for forming a skirt portion and a predetermined alloy powder 200 for forming a head portion to form a skirt portion and a head portion of a piston through separate processes, respectively. The material of the alloy powder 200 (material having excellent high temperature properties) and the material of the skirt portion (material having excellent moldability) are formed of different materials.

This is different from the conventional casting method of the piston manufacturing method or forging method of the piston manufacturing method by forming the material of the head portion and the skirt portion differently, it is a piston manufacturing method excellent in forging formability (manufacturability) with good forging in high temperature environment. Will be provided.

To this end, the alloy cut piece 100 is formed of an alloy having excellent moldability than the alloy powder 200, the powder 200 is formed of an alloy having a higher strength and heat resistance of the cut piece 100 In the case of the piston head, it can be formed using high temperature fatigue strength, high temperature tensile strength, yield strength, low thermal expansion coefficient and density, and high strength and light weight material so as to withstand high temperature environment. In this case, it may be formed using a material having excellent moldability in order to facilitate forging rather than high temperature properties.

To this end, a step (S10) of forming a predetermined alloy cut piece 100 for forming the skirt part and a step (S20) of manufacturing a predetermined alloy powder 200 for forming the head part are performed.

The step (S10) of forming the alloy cut piece 100 is specifically a step of preparing a skirt ingot to be a raw material of the cut piece 100 (S11) and the alloy after melting and alloying the skirt ingot continuous casting method It may be configured to include a step (S12) for producing a billet (billet) and the step (S13) to form the cut piece 100 by cutting the billet.

Preparing the skirt ingot (S11) is a step of preparing the raw material of the cutting piece 100, the skirt ingot should be formed of a material capable of excellent forging formability of the skirt portion, Al, Si, Ni, Cu, and Mg. In one embodiment, the Si ratio is about 10 to 13% by weight in the skirt ingot, and in the case of Ni, Cu, and Mg, respectively, to be included in the range of 6% or less by weight, and most of the rest is filled with Al. It is preferable. However, since this is only a preferred embodiment, it is not limited to this component composition.

Then, the skirt ingot is placed in a predetermined mold, and melted and alloyed using a continuous casting method to prepare a billet (billet) (S12). The billet is cast in a rod shape as shown in FIG. 2, and then after the step S13 of cutting the billet to a predetermined size, an alloy cut piece 100 is formed.

On the other hand, the present invention is subjected to the step (S20) of manufacturing the alloy powder 200 from a separate material from the alloy cut piece 100 as described above.

Step (S20) of preparing the alloy powder 200 is specifically a step of preparing a head ingot to be a raw material of the powder 200 (S21) and the head ingot to dissolve the powder by rapid cooling solidification method (atomization) It may include a step (S22) to manufacture in (200).

In the case of the head ingot is composed of a different composition of the skirt ingot or even the same composition is used to form a different type of alloy with the cut piece 100 by varying the composition ratio.

To this end, the head ingot, the composition of the Si ratio of 12 to 17% by weight, the Fe ratio of 4.5 to 5.5% by weight, the Cu ratio of 1.5 to 2.5% by weight, the Mg ratio of 0.5 to 1.5% by weight, the rest is It may be characterized by being filled with Al.

Here, the Zr ratio of the head ingot may be added 0.1 to 1.5% by weight and the Al ratio may be reduced to a corresponding ratio, and further, the Ni ratio of the mixture is added to 0.1 to 1.5% by weight and the Al ratio is corresponding thereto. Can be reduced in proportion.

First, the Al content occupies the largest portion, and may occupy about 70 to 85 wt%. In the present invention, the aluminum alloy is made, and Al corresponds to the main component in the present invention.

Next, it is preferable that content of Si is made to contain about 12 to 17 weight% in view of the composition ratio of the alloy powder 200 mentioned above. In this case, Si not only improves the wear resistance of the alloy but also reduces the coefficient of thermal expansion. However, since Si increases the forging formability as the content of Si increases, it may be selectively used within the range in consideration of the required physical properties and the design of the piston. .

Further, the content of Fe, which is an element that improves high temperature properties, is preferably such that about 4.5 to 5.5 wt% is essentially contained in consideration of the composition ratio of the alloy powder 200 described above, and the calculation of the composition range is made of alloy powder ( This is because the Fe content may change during the manufacturing process of 200).

And, the content of Cu is 1.5 to 2.5% by weight, the content of Mg is about 0.5 to 1.5% by weight can be prepared to change the content in the manufacturing process of the alloy powder 200.

In addition, content of Zr makes it possible to contain Zr in the Example of this invention, and to classify as containing and not containing Zr.

In the case of containing Zr, the ratio is 0.1 to 1.5% by weight, which is also to prepare for the reduction of the content in the manufacturing process of the alloy powder 200.

Furthermore, the content of Ni is classified as containing and not containing Ni, and in the case of containing Ni, the ratio is 0.1 to 1.5% by weight to prepare for a decrease in content during the manufacturing process of the alloy powder 200. .

Then, the head ingot is dissolved and manufactured into powder 200 by rapid cooling (atomization) (S22).

In order to manufacture the alloy powder 200, it is preferable to use a gas spraying method among the quenching and solidification methods, and to use the same to prepare the alloy powder 200 having a spherical shape or irregular shape to be described below.

In the present invention, when the alloy powder 200 is manufactured, the atmosphere of the atomizer may be controlled by a vacuum or inert gas atmosphere, and in the case of vacuum, the degree of vacuum may be set to 5 × 10 ⁻² torr. In addition, an inert gas (argon or nitrogen) is used to prevent oxidation of the powder 200 as the sprayed gas. In the case of rapid solidification, the pressure of inert gas is about 10 ~ 15bar. In addition, the method of using dried compressed air as a spray gas to reduce the manufacturing cost in powder production and the method of obtaining a quench-solidified structure regardless of the size of the powder by spraying droplets onto the wall of the rotating chamber where water flows (SWAP Process) is also not excluded from the present invention.

In addition, in order to prevent the solidification of the melt occurs at the nozzle end during the spraying of the melt to prevent clogging of the nozzle to use the nozzle diameter of 2mm.

The dissolution of the mixture for preparing the alloy powder 200 is performed by dissolving the mixture for preparing the alloy powder 200 at a temperature of about 800 to 1000 ° C. using an induction furnace or an arc furnace for smooth dissolution of the high melting point alloy element. After maintaining for 20 minutes to prepare an alloy powder 200 through quench solidification.

Then, the preform (Preform) by inserting the alloy cut piece 100 and the alloy powder 200 formed as described above into a predetermined mold and applying heat and pressure to diffusely bond the cut piece 100 and the powder 200. Step 300 is performed to form a sintering step (S30).

This is also a characteristic step of the present invention, in the case of the present invention does not dissolve the alloy powder 200 or use it to manufacture a separate billet (billlet), etc., the alloy powder 200 itself is directly put into the mold alloy By diffusion bonding with the cutting piece 100, the manufacturing process is simplified to reduce the work time and cost.

At this time, the alloy cutting piece 100 to be the skirt portion is placed in the lower portion of the mold and the alloy powder 200 is put into the upper portion by applying heat and pressure to be mutually diffusion bonded to form a preform (Preform) (300) It is preferable. As an example of the present invention for easily applying heat and pressure, when using the rapid sintering principle (electric pressure sintering method or discharge plasma sintering method), the purpose of manufacturing the preform 300 of heterogeneous materials may be more usefully achieved.

Thereafter, the preform 300 is forged by using a predetermined forging machine or the like to produce a piston (S40). By using the forging method that presses high pressure press to make piston, coarse material is changed finely and finely by high pressure and plastic deformation, and it is possible to manufacture piston with smooth surface and excellent durability.

In the case of the piston 400 manufactured by the method of manufacturing a forged piston according to the present invention, as shown in FIG. 3, the head portion 410 of the piston 400 which is subjected to high temperature and pressure is formed of a high strength material having excellent high temperature properties. In addition, the skirt 420 of the piston 400, which is subjected to relatively high temperature and less pressure, is formed of a material having excellent moldability, thereby simultaneously achieving high temperature properties and ease of manufacture of the piston. Here, since the pin boss portion 430 of the piston is included in the skirt portion 420 is formed of a material having excellent moldability.

In addition, by cutting the piston produced through the forging step (S40), and may further include a processing step (S50) for a predetermined surface treatment, thereby making the surface of the forged piston more smooth through The reliability can be further improved.

As described above, the present invention relates to a method of manufacturing a piston using a forging method, and has an advantage of manufacturing a piston having a light weight and excellent durability compared to a casting method, and in particular the head and skirt of the piston. By varying the material, the head of the piston is formed of a material that can withstand high temperature environments. The material of the skirt is formed of a material that is excellent in formability, thereby facilitating forging and making it possible to withstand high temperatures. There is an effect that can be produced. In addition, in order to form the head portion, the alloy powder 200 is put into a predetermined mold and sintered to form a preform 300 directly, so that it is not necessary to go through the step of forming a separate billet through the alloy powder 200. Work time and costs are reduced.

100: alloy cutting pieces
200: alloy powder
300: Preform
400: forged piston
410: piston head
420: piston skirt
430: piston pin boss

Claims (9)

In the manufacturing method of the forged piston comprising a head portion and a skirt portion (hereinafter, including a pin boss portion),
Manufacturing a predetermined alloy cut piece for forming the skirt portion;
Preparing a predetermined alloy powder for forming the head portion;
A sintering step of forming a preform by injecting the cut pieces and the powder into a predetermined mold and applying heat and pressure to diffusely bond the cut pieces and the powder; And
Forging the preform;
The cutting piece and the powder is a forging piston manufacturing method characterized in that the heterogeneous material different in formability and strength and heat resistance. The method of claim 1,
The cutting piece is formed of an alloy having a formability higher than the powder, the powder is a forging piston manufacturing method, characterized in that formed with an alloy of higher strength and heat resistance than the cutting piece. The method of claim 1,
The step of manufacturing the cut piece,
Preparing a skirt ingot to be a raw material of the cut piece;
Dissolving and alloying the skirt ingot to produce a billet through a continuous casting method; And
Cutting the billet to form the cutting piece; forging piston manufacturing method comprising a. The method of claim 1,
Preparing the powder,
Preparing a head ingot to be a raw material of the powder; And
And dissolving the head ingot to produce the powder by quenching and solidification (atomization). The method of claim 3,
The skirt ingot comprises Al, Si, Ni, Cu and Mg as a component composition, the Si ratio is 10 to 13% by weight manufacturing method of the forged piston. 5. The method of claim 4,
The head ingot,
The component composition is Si to 12 to 17% by weight, Fe to 4.5 to 5.5% by weight, Cu to 1.5 to 2.5% by weight, Mg to 0.5 to 1.5% by weight, the remainder is filled with Al forging Piston manufacturing method. The method according to claim 6,
Zr ratio of the head ingot is added 0.1 to 1.5% by weight and Al ratio is reduced to a corresponding ratio. The method of claim 7, wherein
The forged piston manufacturing method, characterized in that the Ni ratio in the head ingot is added 0.1 to 1.5% by weight and the Al ratio is reduced to the corresponding ratio. The method of claim 1,
And forging and surface treatment after the forging of the preform.

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