Aluminum alloy for die casting and die casting mold manufactured using the same

Abstract

The present disclosure relates to an aluminum alloy for die casting, more particularly, to an aluminum alloy for die casting which has high corrosion resistance, strength and castability. The embodiments of the present disclosure provide an aluminum alloy for die casting comprising a composition ratio having an aluminum (Al) content which occupies almost the composition ratio of the aluminum alloy; a magnesium (Mg) content of 2.5˜3.0%; a silicon (Si) content of 9.6˜0.5%; a zinc (Zn) content of 0.5% or less; and a copper (Cu) content of 0.15% or less.

Claims

1. An aluminum alloy for die casting comprising: aluminum (Al), magnesium (Mg), silicon (Si), zinc (Zn), copper (Cu), beryllium (Be), iron (Fe), manganese (Mn), nickel (Ni), tin (Sn), lead (Pb), titanium (Ti), boron (B), and calcium (Ca), wherein the aluminum alloy comprises by weight: 2.6 to 3.0% magnesium (Mg); 9.9 to 10.5% silicon (Si); 0.5% or less zinc (Zn); 0.15% or less copper (Cu); 0.5 to 0.6% manganese (Mn); 0.03% or less nickel (Ni); 0.03% or less tin (Sn); 0.05% or less lead (Pb); 0.01 to 0.02% titanium (Ti); 0.002 to 0.004% boron (B); 0.01% or less calcium (Ca); iron (Fe) greater than 0.65% and less than or equal to 0.7%; 0.005% to 0.008% beryllium (Be); and a balance including aluminum (Al) and unavoidable impurities.

2. The aluminum alloy of claim 1, wherein Fe is about 0.7% of the aluminum alloy by weight.

3. A die casting product manufactured by using the aluminum alloy of claim 1.

4. The die casting product of claim 3, wherein a temperature of a molten metal for manufacturing the die casting product corresponds to a temperature of a molten metal of an ALDC-3 alloy.

5. The die casting product of claim 4, wherein the temperature of the molten metal of the ALDC-3 alloy is 650° C.

6. The die casting product of claim 3, wherein the die casting product has a corrosion resistance property that corresponds to a corrosion resistance property of an ALDC-6 alloy, and a castability property that is greater than a castability property of an ALDC-3 alloy.

7. The die casting product of claim 3, wherein the die casting product has a breaking strength in a range from 3600 to 4000 kgf/cm.sup.2.

8. The die casting product of claim 3, wherein the die casting product includes a spider that is configured to couple to a rear wall or lower wall of a drum, the drum being configured to be mounted in a washing machine, and wherein the spider is configured to transmit drive force of a motor to the drum.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings, which are given by illustration only, and thus are not limitative of the present invention, and wherein:

(2) FIG. 1 illustrates a spider which is able to be manufactured of an aluminum alloy in accordance with one embodiment of the present disclosure;

(3) FIG. 2 includes pictures which are showing the results of salt spray tests which are performed to a spider manufactured of the conventional ALDC-3 and ALDC-6 and a spider manufactured of the aluminum alloy in accordance with the embodiment;

(4) FIG. 3 is a table showing composition ratios of the conventional ALDC-3 and ALDC-6 and a composition ratio of the aluminum alloy in accordance with the embodiment; and

(5) FIG. 4 is a table showing a composition ratio of the aluminum alloy in a test sequence to gain the aluminum alloy in accordance with the embodiment.

DESCRIPTION OF SPECIFIC EMBODIMENTS

(6) Description of an aluminum alloy for die-casting will now be given in detail according to exemplary embodiments disclosed herein, with reference to the accompanying drawings.

(7) Embodiments of the present disclosure start from a point in question about the fact or theory accepted in tolerate manners. In other words, the present disclosure starts from a question whether the increase of the MS content which is an excellent physical property in the aspect of the corrosion resistance is compatible with the increase of the Si content which is an excellent physical property in an aspect of the castability.

(8) Completely ignoring the theory that the increase of the silicon (Si) will result in the increase of transition corrosiveness while effective in improving the castability, there is an attempt to increase the Si content based on ALDC-6. In this instance, the attempt is resolutely done, ignoring the expectation in theory that the castability is increased while the corrosion resistance is deteriorated.

(9) Hereinafter, an overall process to gain an aluminum alloy in accordance with one embodiment of the present disclosure will be described in detail, referring to FIG. 4. The other except the contents shown in FIG. 4 is almost aluminum and some impurities might be contained.

(10) In a first test which uses ALDC-6, it is described that the satisfactory physical property for the castability failed to be gained. The amount of the aluminum alloy content used in additional 7 tests, in other words, the total 8 tests and the results of the physical properties gained in the tests will be described in detail. The components of ALDC-3 and ALDC-6 are shown in FIG. 3.

(11) On the premise that ALDC-6 satisfies the required corrosion resistance property, a test for increasing the silicon content is performed based on the ALDC-6 content.

(12) In the second test, the silicon content is increased from 0.1% or less to 1.8˜2.3%. It is checked based on the result of the test that the required castability property is not gained.

(13) In the third test, the silicon content is increased more to 5.6˜6.0%. At this time, it is checked based on the result of the test that the castability is improved but that the required castability property is not gained. Also, the breaking strength is 2900 kgf/cm.sup.2 which is not enough to satisfy the required value. According to the result of the third test, when the silicon content is increased, the castability is improved unlike the theory and the increase of the strength is required.

(14) It is necessary to decrease the contents of the other elements according to the increase of the silicon content. In theory, Zinc (Zn) is known as the element capable of effectively increasing the tensile strength and the hardness degree. However, there is an attempt to decrease the Zn content in response to the increased Si content which is the fourth test.

(15) In the fourth test, the similar castability and corrosion resistance properties are gained to the properties gained in the third test. Also, it is checked that the strength is improved about to 3200 in the fourth test. In other words, it is known that the result of the fourth test puts a different complexion on the general knowledge or theory about the Si content and the Zn content. Different from the expectation, the Si content and the Zn content bring the improved result in the castability and the strength.

(16) Accordingly, the fifth test is performed to increase the Si content more and decrease the Zn content more. In the test, the Si content is increased to 9.6˜105% and the Zn content is decreased to 0.5% or less.

(17) It is figured out based on the result of the fifth test that the required level is satisfied in the castability, corrosion resistance and strength properties. More specifically, the test result is different from the general knowledge or theory about the Si, Mg and Zn contents.

(18) It may be checked based on the composition ratio of the aluminum alloy gained from the fifth test shown in FIG. 5 that all of the castability, the corrosion resistance and the strength may satisfy the required properties. In other words, a new aluminum alloy having the equal level of castability to ALDC-3 and the equal level of corrosion resistance to ALDC-6 can be invented out of the general knowledge and common sense. In addition, a new aluminum alloy having the equal level of strength to ALDC-3 and ALDC-6 may be invented.

(19) Hence, a test about whether to increase the strength more is performed. The six and seventh tests are performed to test whether the strength is increased by increasing the copper (Cu) content. That is because copper is known in theory as the element capable of increasing the tensile strength and the hardness level.

(20) When the Cu content is increased from a conventional level of 0.1% or less to 0.4˜0.6%, it is identified that the strength property is improved as expected. However, the corrosion resistance property is decreased more as figured out from the result of the sixth test.

(21) Accordingly, in the seventh test, the Mg content, which is related with the increase of the corrosion resistance under similar conditions to the sixth test conditions, is increased from a conventional level of 2.0˜3.0% to 3.0˜3.5%. However, the corrosion resistance is not improved based on the result of the seventh test, different from what is expected.

(22) As a result, it is not easy to increase the strength more noticeably than the result of the fifth test. The eighth test is performed to gain the result that the strength is increased by minimizing the increase of the Cu content, while the corrosion resistance property is not decreased.

(23) More specifically, the Cu content is increased in the eighth test more than in the fifth test and less than in the sixth and seventh tests. In the eighth test, the Mg content is increased to 2.6˜3.0%. As expected, the corrosion resistance and castability properties satisfy the required level and the strength property also satisfies the required level. Through the eighth test like the fifth test, a new aluminum alloy is invented and it is known that the results of the two tests are very similar. The corrosion resistance and castability properties of the aluminum alloy invented through the eighth test are almost equal to those of the aluminum alloy invented through the fifth test, while the strength property of the aluminum alloy invented in the eighth test is improved a little.

(24) Through the fifth and eighth tests, the composition ratio of the new aluminum alloy capable of improving all of the corrosion resistance, castability and strength properties may be found out. Such the new aluminum alloy may be referred to as “ALDC6-Si10”. As mentioned above, that aluminum alloy is derived from ALDC-6 and the difference between them is the difference of the Si contents.

(25) Through the several tests, the attempts beyond the general common sense in the industry are performed and the result beyond the general knowledge can be gained accordingly.

(26) Meanwhile, a spider of a washing machine is manufactured of the aluminum alloy in accordance with the embodiment of the present disclosure and it has to be considered whether the manufactured spider satisfies the conditions required by the manufactured spider.

(27) First of all, there are following effects in an aspect of the primary cost.

(28) Compared with the spider manufactured by using the conventional ALDC-3 and painting and ALDC-6, the spider manufactured by using ALDC6-Si10 has a lowered manufacturing cost which is approximately 86˜94% of the conventional manufacturing cost. When it is premised that such spiders are mass produced, the manufacturing cost can be lowered remarkably. Aluminum occupies almost of the entire content ratio and the other elements occupies a little so that the primary cost may be differentiated by a minute difference of the ALDc-3, ALDC-6 and ALDC6-Si10 contents. Even when the unit cost of a specific element is changed drastically, the overall primary cost is affected little.

(29) Especially, in case of ALDC-6, the temperature of a molten metal is required to be 700° C. and it is not easy to manufacture the molten metal having such a temperature and there is a disadvantage of a high manufacturing cost. However, the temperature of a molten metal required by ALDC6-Si10 is 650° C. which is similar to that of a molten metal required by ALDC-3 so that there may be little change of the conventional manufacturing process in case of ALDC6-Si10. Also, there may be little change of a mold when using ALDC-3 and ALDC6-Si10.

(30) Accordingly, only the material of the mold is changed and the mold and manufacturing process for die-casting are not changed in manufacturing process so that the initial investment cost can be also reduced noticeably.

(31) Not only the primary cost and expense but also the manufacturing process and distribution may be reduced. Therefore, not only the decrease of the primary cost but also moral gains can be expected which are created from the smooth supply and demand of products and factory planning and scheduling.

(32) The result of the corrosion resistance in a high temperature boiling environment of 400 cycles after a salt spray test which is the most severe environment in the washing machine is very satisfactory.

(33) FIG. 2 includes pictures which are showing the results of salt spray tests which are performed to a spider manufactured of the conventional ALDC-3 (FIG. 2(a)) and ALDC-6 (FIG. 2(b)) and a spider manufactured of ALDC6-Si10 (FIG. 2(c)). It can be checked that the corrosion resistant effect in ALDC6-Si10 is remarkably good such as a corrosion generation position and a corrosion generation size.

(34) All of the properties required by a test list of the spider about a structure exterior, measurements, the salt spray test, a humidity resistance test, a detergent resistance test, a fabric softener test, a bleacher (oxygen-based) resistance test, a bleacher (chloride-based) resistance test and cooling/heating resistance may be satisfied.

(35) Moreover, all of the properties required by a test list of the spider for an assembly attached to a drum and a test list of the entire washing machine may be satisfied.

(36) Meanwhile, for the aluminum die casting, an ingot is generally melted and used. However, a scrap which will be left after the aluminum die casting is re-used. More specifically, after melted and hardened, the ingot is re-melted and re-used. It is melted again and used in case the manufactured mold has an error or it is recycled. Especially, when re-using such the scrap, Mg might be oxidized only to deteriorate the physical properties of the aluminum.

(37) Accordingly, it is preferred that the return scrap is used by preventing the oxidization of Mg so as to lower the manufacturing cost and protect the environments.

(38) In the fifth and eighth tests shown in FIG. 1, the Beryllium (Be) content is 0.005˜0.008% to facilitate the re-use of the return scrap.

(39) According to the embodiments mentioned above, the aluminum alloy may have a chemical consisting of a balance of Aluminum (Al), a plurality of elements and unavoidable impurities. The contents of Aluminum and other elements are controlled except the unavoidable impurities. Also, an amount of each component is given in “wt-%” based on the total weight of the aluminum alloy.

(40) According to the embodiments mentioned above, the basket with the beautiful design and the sub storage compartment including the same may be realized. Also, the user is able to manipulate the moving basket smoothly. Various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.