KR20030048704A - High strength semi solid aluminum tappet and its production process - Google Patents

Abstract

PURPOSE: A high strength semi solid aluminum tappet capable of improving gas mileage and reducing noise by injection molding semi solid aluminum alloy to manufacture the tappet, thereby reducing moment of inertia due to weight reduction as a whole, and a manufacturing method of the aluminum tappet are provided. CONSTITUTION: The manufacturing method of a high strength semi solid aluminum tappet comprises the processes of manufacturing a semi solid aluminum billet after spheroidizing in the cooling process using rotary power of an electronic agitator installed on the outer part of a mold while continuously casting aluminum alloy having a composition comprising 5.4 to 6.4 wt.% of Si, 0.14 wt.% of Fe, 2.5 to 3.5 wt.% of Cu, 0.03 wt.% of Mn, 0.3 to 0.45 wt.% of Mg, 0.03 wt.% of Ni, 0.05 wt.% of Zn, 0.2 wt.% of Ti and 0.02 to 0.04 wt.% of Sr horizontally and vertically to a temperature of 650 to 610 deg.C in tundish; rapidly and uniformly reheating the semi solid aluminum billet to a temperature of 575 to 585 deg.C using a low frequency induction heater; injection molding a semi solid slug in the slurry state; and performing heat treatment at T6 for 4 hours at 520 deg.C and 8 hours at 160 deg.C.

Description

High strength semi solid aluminum tappet and its production process

The present invention relates to a high-strength reaction solid aluminum tappet and a method of manufacturing the same, and more particularly, to a solid-state aluminum tappet excellent in formability and corresponding to the mechanical properties of a material for producing a tappet and a method of manufacturing the same.

In general, an engine of a vehicle is divided into a stationary part such as a cylinder block and an intake and exhaust device, and a moving part which is actually moved by combustion. In particular, the moving part is divided into a piston and a crank mechanism for generating rotational force by combustion of the mixer, and a valve opening / closing mechanism for opening and closing the intake / exhaust valve according to the movement of the mechanism.

As shown in FIG. 4, the valve opening / closing mechanism includes an intake / exhaust valve 10 mounted on the valve seat 110 of the cylinder head 100, and a cam shaft 20 that opens and closes the intake / exhaust valve 10. ) In particular, a tappet 11 is provided at the upper end of the intake and exhaust valve 10 so as to be in direct contact with the cam 21 of the cam shaft. In addition, in particular, the tappet 11 is a portion in which the cam portion repeats contact and non-contact by driving the cam shaft, and uses a lot of hydraulic pressure to automatically adjust the valve gap.

Such tappets are usually made of steel and used for the manufacturing method thereof as shown in FIG. 5.

However, the conventional tappet is made of a steel material, and the following problems occur because the manufacturing process of the various steps as described above.

1) The oil passage is complicated to allow automatic valve clearance adjustment, resulting in an increase in the overall weight of the tappet.

2) This results in a problem that the tappet, which repeats the vertical movement at high speed, affects the moment of inertia according to the weight, which in turn lowers the engine performance.

3) Since tappets are made of steel blocks and other steel blocks, which are usually made of aluminum alloys, when the vehicle is driven for a long time, the difference in coefficient of thermal expansion of these different materials (24 for aluminum, about 9 for steel) In order to eliminate this, the assembly space is largely manufactured to eliminate this problem, and the chattering phenomenon occurs when the tappet vibrates during high speed driving of the engine.

The present invention has been made in view of this point, by producing a tappet by injection-molding reaction-alloy aluminum alloy whose mechanical properties are equivalent to steel material, the moment of inertia can be reduced by reducing the overall weight, thereby improving fuel efficiency and reducing noise. It is an object of the present invention to provide a high strength reaction solid aluminum tappet and its manufacturing method.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing (1) general tissue (dendritic tissue) and (2) reactive solid tissue (sphered tissue) according to the present invention;

2 is a photograph showing a metal sludge state according to the present invention;

Figure 3 is a photograph showing the reaction solid state after heat treatment according to the present invention,

4 is a cross-sectional view schematically showing a conventional valve device;

5 is a flowchart showing a conventional tappet manufacturing method.

[Description of Symbols for Main Parts of Drawing]

10: intake and exhaust valve 11: tappet

20: cam shaft 21: cam

100: cylinder head 110: valve seat

The manufacturing method according to the present invention for realizing this is an electronic stirring device installed outside the mold during continuous casting of aluminum alloy having a composition as shown in the following table at a temperature of 650 to 610 ° C. in a tundish. Preparing a solid aluminum billet after spheroidizing during the cooling process by using the rotational force; Rapidly and uniformly reheating the reaction solid aluminum billet at 575 to 585 ° C. using a low frequency induction heating apparatus; Injection molding the slurry solids slug; And, it characterized in that the process consisting of a heat treatment for 520 ℃ × 4h, 160 ℃ × 8h at a temperature T6.

In addition, the tappet according to the present invention is the rotational force of the electronic stirring device installed outside the mold during continuous casting in the vertical or horizontal direction of the aluminum alloy of the composition of [Table 1] at a temperature of 650 ~ 610 ℃ in the tundish (Turndish) Spheroidizing process during the cooling process, rapid homogeneous reheating of the reaction solid aluminum billet to 575-585 ° C. using a low frequency induction heating device, and then injection molding the reaction slurry slug in slurry state at 520 ° C. × 4 h, Heat treatment at 160 ° C. for 8 h.

Hereinafter, with reference to the accompanying drawings, the configuration and effect of the present invention will be described.

The present invention aims to simplify the manufacturing process while producing a tappet from an aluminum alloy to reduce its overall weight.

In the manufacturing process of the present invention, the rotational force of the electronic stirring device installed outside the mold during the continuous casting in the vertical or horizontal direction of the aluminum alloy having the composition shown in Table 1 in the tundish at a temperature of 650 ~ 610 ℃ in the first process Proceeds during the cooling process.

1 shows a general casting structure and the reaction structure according to the present invention, (1) shows a general casting structure (resin structure, Dendrite), (2) the reaction structure according to the present invention ( Demonstrate Globular Structure. Here, it can be seen that the reaction solid structure is uniform and has no shrinkage (shrinkage) compared to the general cast structure.

The second process is then a process of rapidly reheating the spheroidizing billet. In this process, a low-frequency induction heating apparatus is used at 575-585 ° C. under the condition of rapidly and uniformly reheating the reaction high aluminum billet. In this reheating process, the process structure (black in the drawing) is liquefied in (2) of the accompanying drawings to obtain an aluminum metal slurry in which a solid phase and a liquid-solid coexist.

Figure 2 shows the metal slurry obtained in the second process. The metal slurry is in a state capable of maintaining its own shape and becomes a state capable of being cut into slugs in a pseudo-plastisity state in which viscosity is sharply lowered like a polymer.

In the third step, the reaction slurry is subjected to injection molding. In the injection molding, the slug is put in the sleeve in the same manner as in the conventional art, and filled into the cavity at a predetermined pressure, preferably at a pressure of 700 to 1200 MPa and a cavity of the mold to obtain a product.

The product thus obtained is subjected to heat treatment as the last step. At this time, the heat treatment temperature is a heat treatment for 520 ℃ × 4h, 160 ℃ × 8h at T6. Figure 3 shows the reaction solid tissue state of the product that has completed this heat treatment process. As can be seen from the reaction solid structure after heat treatment, primary aluminum (spherical) is more spheroidized, and the mechanical properties are further improved through the T6 heat treatment process.

Table 2 compares the mechanical properties of the reaction solid aluminum alloy according to the present invention with conventional steel materials.

Yield Strength (YS) Mpa Tensile Strength (UTS) Mpa Elongation (%) Invention 310-330 400-410 4-7 Conventional 800-1100 1000-1400 8-12

Therefore, the tappet according to the present invention and the manufacturing method thereof can be produced by the injection molding method of the tappet of a level corresponding to the forged material using the high-alloy aluminum alloy.

As described above, the present invention obtains the following effects by manufacturing a tappet by injection molding into a reactive solid aluminum alloy.

1) As it is possible to manufacture tappets from aluminum alloy, which is lighter in weight than steel, it has the effect of reducing fuel consumption and reducing noise (reducing chattering phenomenon).

2) Cost savings can be achieved by shortening the number of manufacturing processes.

3) Engine performance can be improved.

Claims (2)

After continuous casting of aluminum alloy with the composition as shown in the table below in the vertical or horizontal direction at a temperature of 650 to 610 ° C. in a tundish, the reaction is performed after spheroidization during the cooling process by using the rotational force of the electronic stirring device installed outside the mold. Manufacturing an aluminum billet; Rapidly and uniformly reheating the reaction solid aluminum billet at 575 to 585 ° C. using a low frequency induction heating apparatus; Injection molding the slurry solids slug; And, high temperature reaction solid aluminum tappet manufacturing method, characterized in that consisting of a process of heat treatment for temperature 520 ℃ × 4h, 160 ℃ × 8h at temperature T6. The aluminum alloy of the composition of [Table 1] was spheroidized during the cooling process by using the rotational force of the electronic stirring device installed outside the mold during continuous casting in a vertical or horizontal direction at a temperature of 650 to 610 ° C. in a tundish. After rapid homogeneous reheating of the solidified aluminum billet at 575 to 585 ° C. using a low frequency induction heating apparatus, injection molded slug in the form of slurry was injected and heat treated at 520 ° C. × 4 h and 160 ° C. × 8 h at T6. High strength reaction high aluminum tappet.