KR100669603B1 - Manufacturing method of aluminum wheel that make use of fusion forging method - Google Patents

Abstract

A manufacturing method of an aluminum wheel using a high pressure fusion forging method is provided to improve productivity and mechanical property of the aluminum wheel by pre-heating the mold at a relatively low temperature, pressing the melted liquid at super-high pressure, and reducing the manufacture-cycle time. A manufacturing method of an aluminum wheel using a high pressure fusion forging method comprises a step of melting a melted liquid(F) at 800~850‹C; a step of pre-heating the mold at 120~250‹C and injecting the melted liquid in upper and lower molds(55,56); a step of applying the pressure of 800~1000Kg/cm^2 to the melted liquid injected in the molds by a squeeze pin(S) and a piston(P); and a step of keeping the pressing time for 20~120 seconds. The temperature of the melted liquid injected in the mold is within 650~750‹C.

Description

MANUFACTURING METHOD OF ALUMINUM WHEEL THAT MAKE USE OF FUSION FORGING METHOD}

1 is a cross-sectional view showing a squeeze casting casting apparatus to which the present invention is applied;

Figure 2 is a photograph of the structure of the aluminum wheel produced by the present invention,

Figure 3 is a schematic cross-sectional view showing a low pressure casting device used in general low pressure casting.

Figure 4 is a photograph of the structure of the aluminum wheel produced by the low pressure casting of Figure 3;

* Explanation of symbols for the main parts of the drawings

S: Squeeze Pin P: Piston

F: molten metal 55: upper mold

56: lower mold

The present invention relates to a method for manufacturing an aluminum wheel using a high pressure melt forging method, and more specifically, there is no pore or shrinkage hole in the casting, and has a uniform microstructure, which can reduce weight and improve mechanical properties. The present invention relates to a method for manufacturing an aluminum wheel using a high pressure melt forging method.

In general, in order to manufacture an aluminum wheel of an automobile, an aluminum alloy is manufactured by forming a wheel through gravity casting or low pressure casting, and then cutting unnecessary parts to manufacture an aluminum wheel.

In addition, after manufacturing the wheel through the low-pressure casting, the rim is cast separately to combine them by welding to produce an aluminum wheel.

That is, the aluminum alloy is melted and injected into the low pressure casting apparatus, and then the molten alloy is injected into the mold while pushing up the molten metal. When the molten solidifies, the mold is separated to take out the product.

In the low pressure casting, the molten metal having a temperature of about 700-750 ° C. is pressurized at a pressure of about 1 Kg / cm 2 or less, and the molten metal is precisely injected into the mold while applying the pressure to the molten metal relatively slowly.

In the general low pressure casting apparatus used in the low pressure casting, as shown in FIG. 3, the crucible 51 is installed so that the molten metal F is injected and stored through the injection hole 50 and the molten metal F is stored in the molten metal F. The lower mold provided with a molten metal heating furnace 53 in which the compressed air injection pipe 52 is applied to apply pressure, and a hot water pipe 54 is installed so that the molten metal F is supplied to the upper portion of the molten metal heating furnace 53. And 55, and an upper mold 56 installed to engage with the lower mold 55 in an elevated manner.

Of course, the upper mold 56 is installed so as to be elevated through the operating means such as a cylinder.

The low pressure casting state described above is described in more detail. After preheating the mold to 450-500 ° C, the molten metal F is heated to 700-750 ° C and the molten metal F is injected into the mold. When it is maintained while pressing for 300-500 seconds, an aluminum wheel having characteristics of approximately 23-26Kg / mm2 in tensile strength, 4-8% elongation, 85min in hardness, and 60-70 µm in size of crystal grains is obtained.

Here, the cycle time of manufacturing the product by the low pressure casting has a period of 400 seconds.

The aluminum wheel produced by the low pressure casting is a photograph shown in Figure 4 is a 200 times magnification with an optical microscope, including shrinkage and gas defects, the crystal grains are large, the density is low, the grain size is large and mechanical characteristics Because of its weakness, the alloying element for reinforcement is added during low pressure casting, and fine precipitated phase is deposited through heat treatment to achieve strength improvement.

However, as described above, when manufacturing the aluminum wheel by using low pressure casting, since pores or shrinkage holes inside the casting are generated, it is difficult to improve the rigidity and toughness of the aluminum wheel, and to maintain the high mechanical properties. There is a problem that the weight of the.

In other words, aluminum wheels made through low pressure casting have low strength and toughness, so it is difficult to fundamentally increase strength and toughness even when reinforcing compounds are added, and the weight of the aluminum wheels is increased to maintain high mechanical properties. It is difficult to satisfy the characteristics of the aluminum wheel to be large.

In addition, since the cycle time of manufacturing the product by the low-pressure casting is too long (400 seconds), there is a problem that the product production efficiency is low.

Accordingly, an object of the present invention is to solve the above problems, by greatly reducing the strength and toughness of the aluminum wheel and to reduce the weight of the aluminum wheel by preventing the generation of pores or shrinkage holes in the casting during manufacture of the aluminum wheel. It is to provide a method of manufacturing an aluminum wheel using a high pressure melt forging method that can achieve the fuel economy improvement of the automobile.

In order to achieve the above object, the present invention provides a method for manufacturing an aluminum wheel by injecting aluminum molten metal into the lower mold,

Melting the melt at a temperature of 800-850 ° C .;

Preheating the mold to 120-250 ° C. and injecting molten metal into the lower mold;

Applying pressure in the range of 800-1000 Kg / cm 2 to the molten metal injected into the mold with a squeeze pin and a piston;

It characterized in that it comprises the step of maintaining the pressing time for 20-120 seconds.

1 is a schematic cross-sectional view of a squeeze casting casting apparatus to which the present invention is applied, and is formed to inject molten metal F in the form of an aluminum wheel, and the upper and lower molds 55 and 56 configured to integrally form a disk and a rim of the wheel. ), And a squeeze pin (S) installed to press the molten metal to the center portion of the lower mold (56) and a piston (P) installed to press the molten metal to the upper and lower molds (55, 56).

That is, when the molten metal F is supplied into the upper and lower molds 55 and 56, the squeeze pin S and the piston P press the molten metal F at a constant pressure from the upper and lower portions, thereby forming the structure of the aluminum wheel. This makes it possible to obtain aluminum wheels which are more compact, which leads to an increase in strength and elongation as well as a very dense grain size.

In more detail, the molten casting or forging aluminum alloy is melted at a temperature of 800-850 ° C. to form a molten metal, the mold is heated to a preheating temperature of 120-250 ° C., and the molten metal F is injected into the lower mold. Done.

At this time, the temperature at the time of pressurizing the molten metal (F) is about 650-750 ℃, the pressure through the squeeze pin (S) and the piston (P) after injection is 800-1000Kg / ㎠ and in the mold at the above pressure The time required for filling the molten metal is about 5-30 seconds and the pressure is maintained for 20-120 seconds.

When the temperature when the above-mentioned molten metal F is injected into the mold is 650 ° C. or lower, the molten metal F cools and is not densely injected to the minute portion of the mold, and defects occur. The fluidity of the fluid is so great that there is a risk of flow out of the mold.

Of course, the temperature of the molten metal (F) corresponds to the conditions when the pressurization pressure is 800-1000Kg / ㎠, the product characteristics of the casting by the above-mentioned pressure casting is 29-33Kg / ㎠, Elongation is 9-16%, and crystal grains are 20-30 µm.

As described above, if the forging while pressing with the squeeze pin (S) and the piston (P) can be injected into the mold and cooled quickly to produce the casting while compacting the structure of the casting, according to the present invention The cycle time is less than 150 seconds.

Compared with the low pressure casting according to Table 1 below, the tensile strength and elongation of the casting can be further improved, and it can be confirmed that the crystal grains are smaller.

division Invention Low pressure casting Tensile Strength (Kg / ㎡) 29-33 23-26 Elongation (%) 9-16 4-8 Hardness (HB) 85 min 85 min Crystal grain (㎛) 20-30 60-70 Manufacturing cycle time (seconds) 150 400 Mold preheating temperature (℃) 120-250 450-500 Press force (Kg / ㎠) 800-1000 1 or less Pressure holding time (seconds) 20-120 300-500

The reduction of the cycle time is because the preheating temperature of the mold is much lower than that of low pressure casting. Therefore, the time required for preheating is saved, and the pressurization is performed at a very high pressure to rapidly fill the fine parts of the mold. By setting it as 1/10 or less compared with low-pressure casting, it becomes possible to manufacture a product by high pressure melt forging very quickly.

Here, the above-mentioned preheating time was able to be 120-250 ° C or less, because not only the temperature of the molten metal F was increased to about 800-850 ° C but also the pressure was increased to 800-1000Kg / cm 2, so that the temperature of the mold was increased. This is because it lowers the product so that the product cools rapidly, thereby miniaturizing the tissue.

The microstructure of the aluminum wheel formed by the super-pressure melting forging as described above is shown in Figure 2 is a photograph taken by the optical microscope, which shows the crystal structure of the aluminum wheel produced by conventional low-pressure casting ( It can be seen that the tissue is very dense compared to the one taken at a 200x magnification with the same microscope as in FIG. 4.

When the crystal structure of the aluminum wheel is dense, fine pores or shrinkage holes do not exist in the wheel, and thus the tensile strength and elongation of the aluminum wheel can be significantly improved compared to the aluminum wheel manufactured by low pressure casting.

In addition, since the preheating temperature of the mold is low, the casting is cooled at a very high speed after casting, thereby improving mechanical properties such as tensile strength and elongation of the aluminum wheel.

As described above, according to the present invention, when the aluminum wheel is cast, the mold is preheated to a relatively low temperature, and the casting is performed while pressing the molten metal at a very high pressure, thereby shortening the cycle time of the casting, thereby improving productivity and mechanically manufacturing the cast aluminum wheel. There is an advantage that the characteristics can be improved, the weight is reduced, resulting in cost reduction.

Claims (3)

In the aluminum wheel manufacturing method for manufacturing an aluminum wheel by injecting molten aluminum into the upper and lower molds, Melting the melt at a temperature of 800-850 ° C .; Preheating the mold to 120-250 ° C. and injecting molten metal into the upper and lower molds; Applying pressure in the range of 800-1000 Kg / cm 2 to the molten metal injected into the mold with a squeeze pin and a piston; Method of manufacturing an aluminum wheel using a high pressure melt forging method, characterized in that it comprises the step of maintaining the pressing time for 20-120 seconds. The method of claim 1, Method of manufacturing an aluminum wheel using a high pressure melt forging method characterized in that the pressure of the molten metal injected into the mold is pressed with a squeeze pin and a piston within the range of 650-750 ℃. The method according to claim 1 or 2, Method of manufacturing an aluminum wheel using a high pressure melt forging method characterized in that the time required for filling the molten metal into the mold by pressing the squeeze pin and the piston within 5-30 seconds.

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