KR20050078510A - Method for casting aluminium alloy brake disc - Google Patents

Abstract

The present invention relates to a method for casting aluminum composite brake discs employing a method of injecting molten metal from the upper center of the brake disc when the molten metal is injected for casting the brake disc.

The present invention can significantly reduce the runner section, which is the movement path of the molten metal, by adopting a method of injecting molten metal from the center of the brake disc during the molten metal injection, thereby significantly reducing the amount of material discarded after casting. By improving the position of the disk friction portion upward through the design change to minimize the amount of precipitation of SiC particles, it provides an aluminum composite brake disk casting method that can improve the workability and surface quality of the brake disk.

Description

Aluminum composite brake disc casting method {Method for casting aluminum alloy brake disc}

The present invention relates to a method for casting an aluminum composite brake disc, and more particularly, to minimize the amount of material discarded after casting by adopting a method of injecting molten metal from the center of the brake disc when the molten metal is injected for casting the brake disc. In addition, the present invention relates to a method for casting an aluminum composite brake disc that can minimize the precipitation of SiC particles in the friction part to increase workability and surface quality.

In general, in the 1990s, many advanced companies have made efforts to replace brake discs made of cast iron with aluminum composite materials to reduce vehicle weight and improve brake performance.

If the brake disc is replaced with aluminum composite material, the weight reduction rate is more than 50%, and the effect is large. Especially, in the case of the disc, the ripple effect is greater.

In addition, when the disk is lightweight as the unsprung weight of the chassis parts, the disk also has the effect of improving handling performance and rideability, and improving overall friction coefficient and improving NVH (noise / vibration). The effect of improving brake performance can be obtained.

To apply aluminum composite material to brake discs, the following basic considerations should be considered.

When braking, it must withstand the heat generated when the kinetic energy is converted into thermal energy.

In addition, the strength to withstand the centrifugal force during rotation and the pressure applied during braking, stable friction coefficient in combination with the friction material, wear-related performance, NVH performance and the like are required.

Considering these basics, many studies have been conducted since the 1990s, especially among advanced companies in foreign countries. As a result, the closest mass production material to date is the method of using Duralcan composite material in which 20% of SiC is dispersed in aluminum alloy. to be.

Duralcan material has more than three times the thermal conductivity of cast iron and about 1.7 times that of Lanxide material, so it has a very good thermal conductivity, which has the advantage of relatively good cooling performance.

These Duralcan materials are sold in the form of ingots and are manufactured by melt casting the brake discs.

Dispersion of the reinforcing particles, one of the most important elements in the composite material, is performed by mechanical stirring, and the subsequent casting process is very similar to the existing aluminum alloy.

However, since the SiC particles sink in the molten state, the molten metal must be continuously stirred to disperse the SiC particles. Since the viscosity is high, it is difficult to remove the gas or impurities into the molten metal. Therefore, the oxidation of the molten metal is suppressed to the maximum using argon gas. shall.

The casting process is almost similar to the casting of the existing aluminum alloy, there is an advantage that can use the existing equipment by adding a few additional equipment.

1 is a schematic view showing a conventional aluminum composite brake disc casting method.

As shown in FIG. 1, an injection hole 10 is provided at one side, a runner 11 which runs horizontally in a predetermined section, and a ceramic filter 12 in a section are provided, and a mold part 13 for forming a brake disc. ) And a brake disc 15 of the aluminum composite material can be manufactured through a casting process provided with an overflow 14 for accommodating the excess melt.

Here, reference numeral 16 denotes a riser, and 17 denotes a disk friction portion in contact with the pad.

However, the existing casting method as described above has the following disadvantages.

1) When the solidification occurs because the distance from the injection hole to the mold part solidified into the actual product is too great, it can be seen that it solidifies from the injection hole to the overflow part and consumes a considerable amount of molten metal in addition to the part processed from the actual brake disc.

For example, as shown in Figure 2, since the part filled with the dotted line is discarded because of the nature of the material can not be recycled in order to produce a single product, about 8 times of the product should be discarded.

This is a huge loss, given that the cost of ingots for aluminum composites is more than 50 times that of steel.

2) SiC particles tend to settle down if they are not stirred due to their high density. However, the conventional casting method takes a lot of time to solidify due to the large amount of molten metal. Because of the bottom, SiC particles in the upper part of the disk friction part, including the riser, settle over time as solidification occurs and accumulate toward the lower part, that is, the disk friction part.

In this case, the disk friction portion is drastically increased due to excessive SiC particles, which makes it more difficult to process the disk friction portion that needs to be precisely processed with a diamond tool.

Therefore, the present invention has been devised in view of the above, by adopting a method of injecting the molten metal from the upper center of the brake disc during the injection of the molten metal to drastically reduce the runner section, which is the movement path of the molten metal, and then discarded The aim is to provide a method for casting an aluminum composite brake disc that can significantly reduce the amount of material.

In addition, the present invention improves the position of the disk friction portion through the design change of the mold portion to improve the amount of precipitation of SiC particles to the maximum, thereby increasing the processability and surface quality of the brake disk aluminum composite brake disc casting There is another purpose in providing a method.

In the present invention for achieving the above object, in the aluminum composite brake disc casting method for casting by injecting a molten aluminum composite material into the mold portion for forming the brake disc and taking out the brake disc casting after solidification, molten aluminum composite material It is characterized in that the injection hole is set at the center of the mold part at the time of injection so that molten metal can be injected vertically downward from the center without a horizontal runner.

In addition, when applying the mold portion for forming the brake disk is characterized in that for applying the mold disposed so that the cavity for forming the disk friction portion in contact with the pad upwards.

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

3 is a schematic view showing the casting method of the present invention, and shows an example in which the position of the inlet for injecting molten metal is set to an optimal position.

As shown in FIG. 3, the injection hole 10 for injecting the molten aluminum composite material is located at the center of the mold part 13 forming the actual product of the brake disc, and thus vertically downwards through the injection hole 10. The molten metal can be injected into the mold unit 13.

Since the vertical downward melt injection method as described above can completely exclude the horizontal runner used when injected from the side as before, the occurrence of the molten material that is solidified in the horizontal runner portion can be reduced.

The ceramic filter 12 is installed at the lower end of the injection hole 10, that is, at the inlet side of the cavity of the mold 13 to remove impurities contained in the molten metal.

In addition, the mold part 13 applied in the present invention has a feature in which a cavity for forming the disk friction part 17, which is a part of the brake disc 15 which is rubbed with the pad, is disposed upward.

As the disk friction part 17 is molded in the upper part of the mold part 17, the disk friction part 17 can be protected from the precipitation phenomenon of the SiC particles that sink downward as the solidification progresses.

That is, it is possible to improve the phenomenon that the SiC particles are precipitated in the disk friction portion relative to the conventional method.

Therefore, when the molten aluminum composite material is injected through the injection hole, the molten metal is filled into a cavity in the mold part and then molded into a shape of a brake disk after solidification. As can be seen, it is possible to minimize the portion to be discarded during processing.

In addition, the disk friction portion is brought upwards, and less time is required to solidify because less molten metal is used, which reduces the time for the SiC particles to settle, thereby reducing the SiC relative to the disk friction portion. It is possible to reduce the precipitation of particles.

Thus, the aluminum composite brake disk manufactured by the casting method of the present invention can be seen in FIG.

Here, it can be seen that only the actual parts of the brake disc are stuck with only four liners and one inlet in the center, and thus, the parts discarded during machining of the brake disc are significantly reduced compared to the conventional ones.

6 is a micrograph showing the SiC particle distribution of the disc friction portion in the aluminum composite brake disc manufactured by the casting method of the present invention.

As can be seen in Figure 6, it can be seen that the distribution of SiC particles per unit area of the disk friction portion is lower than in the conventional Figure 7.

As described above, the present invention provides a casting method including a method of injecting molten metal from the center vertically below the brake disc during injection of the molten metal for casting the brake disc and a method of bringing the position of the disc friction portion upward. The cost saving effect can be reduced by maximally reducing the amount of SiC particles, and the SiC particles can be more evenly dispersed in the aluminum substrate while solving problems such as poor workability caused by the precipitation of heavy SiC particles in the disk friction portion. It is possible to increase the surface quality of the disk friction portion.

1 is a schematic view showing a conventional casting method

Figure 2 is a schematic diagram showing a state after solidification in the conventional casting method

3 is a schematic view showing a casting method of the present invention

Figure 4 is a schematic diagram showing a state after solidification in the casting method of the present invention

Figure 5 is a photograph showing the aluminum composite brake disk produced by the casting method of the present invention

Figure 6 is a micrograph showing the distribution of SiC particles in the disk friction portion in the aluminum composite brake disk produced by the casting method of the present invention

Figure 7 is a micrograph showing the distribution of SiC particles in the disk friction portion in the aluminum composite brake disk produced by a conventional casting method

<Explanation of symbols for main parts of drawing>

10: injection hole 11: runner

12 ceramic filter 13 mold part

14: overflow 15: brake disc

16: riser 17: disk friction

Claims (2)

In the aluminum composite brake disc casting method of casting by injecting a molten aluminum composite material into the mold portion for forming the brake disc and taking out the brake disc casting after solidification, An aluminum composite brake disc casting method, characterized in that the molten metal can be injected vertically downward from the center without a horizontal runner by setting the position of the injection hole in the center of the mold part when the molten aluminum composite material is injected. The method of claim 1, wherein when applying the mold for forming the brake disk, the aluminum composite brake disc casting method, characterized in that for applying the mold disposed so that the cavity for forming the disk friction portion in contact with the pad upwards.