KR20030069656A - Casting method of a small diameter hollow cast-iron product using quartz glass core - Google Patents

Abstract

PURPOSE: A casting method of small diameter hollow cast-iron product is provided to cast the small diameter hollow cast-iron products such as hollow cam shaft, and hollow crank shaft using quartz glass core. CONSTITUTION: In a method for casting an ordinary small diameter hollow cast-iron product comprising a hollow having a smaller diameter compared to thickness so that the cast-iron product has length corresponding to 3 times or more of the diameter of the hollow, the casting method of the small diameter hollow cast-iron product is characterized in that quartz glass core is used to form the hollow, wherein the quartz glass core comprises 99 wt.% or more of SiO2 and 1 wt.% or less of impurities, wherein fire resistant zircon coating material is coated on the surface of the quartz glass core, and wherein the method comprises core fabrication process, mold fabrication process, core installation process, mold connecting process, molten iron injection process, cast-iron product separation process, and core stripping and product completion process.

Description

Casting method of small diameter hollow casting using quartz glass core {CASTING METHOD OF A SMALL DIAMETER HOLLOW CAST-IRON PRODUCT USING QUARTZ GLASS CORE}

The present invention relates to a method for casting small diameter hollow castings, and more particularly, to a method for casting small diameter hollow castings such as hollow camshafts, hollow crankshafts and the like using a quartz glass core.

Spherical graphite cast iron or gray cast iron is used as the material of the camshaft or compressor crankshaft casting used for automobile parts. There are many.

In general, a core made of a molding sand is used to form a hollow in a casting, where the diameter of the hollow must be larger than the thickness of the casting and the length of the casting to be manufactured must be smaller than about three times the diameter of the hollow. In the case of manufacturing small diameter hollow castings such as hollow camshafts, hollow crankshafts, etc., even if the most suitable cell core among the cores made of casting sand is used, the core diameter is small, so that the core is overheated during the injection of molten metal so that sintering occurs. This is because there is a problem in that it is impossible to produce a beautiful hollow casting of a uniform diameter as the core is long due to the length of the core.

Therefore, when the hollow is manufactured in the production of small hollow castings such as hollow camshafts, hollow crankshafts, etc., the diameter of the hollow is smaller than the thickness of the casting and the length of the casting is longer than about three times the diameter of the casting. It may be manufactured by a casting method using a core, but is mainly manufactured by machining since a separate structure for supporting the core is required.

For the reason described above, Utility Model Registration Application No. 20-1994-0037952 discloses a camshaft casting mold for forming a camshaft cavity by joining an upper mold and a lower mold, wherein the core placed in the cavity extends to one side thereof. A core support structure of a hollow camshaft for an internal combustion engine is described, which has a core print, on the opposite side to which the core print is provided, provided with at least one core support means.

Therefore, the present invention uses a core to cast a small diameter hollow casting, such as a hollow camshaft, hollow crankshaft, etc., in which the diameter of the hollow is smaller than the thickness of the casting and the length of the casting is longer than about three times the diameter of the casting. In the case, it is based on the subject to provide the casting method of the small diameter hollow casting which can prevent the sintering of the core at the time of melt injection, and can cast the beautiful hollow casting of uniform diameter.

The above object is achieved by a method of casting a small diameter hollow casting according to the present invention using a quartz glass core.

Hereinafter, a method of casting a small diameter hollow casting according to the present invention will be described in detail.

The casting method of small diameter hollow castings according to the present invention is characterized by using a quartz glass core instead of a core made of a conventionally used casting sand.

The quartz glass core preferably has an SiO ₂ content of 99% or more and an impurity content of 1% or less, wherein the impurities contained in the quartz glass core are used in the production of quartz glass cores such as Al ₂ O ₃ , Fe ₂ O ₃ , and the like. It is inevitably included.

Quartz glass, also commonly referred to as silica glass, is formed only by a reticulated structure of SiO ₂ without any net modified ions, and is obtained by melting pure silica or synthesized by hot gas phase reaction of SiCl ₂ . The softening point of the quartz glass is 1500 ° C. or more, the expansion coefficient is 5.5 × 10 ⁻⁷ / K, the resistance to rapid quenching and quenching is strong, the corrosion resistance and elasticity performance is good, and it transmits ultraviolet rays up to about 200 nm. do. Although melting requires a high temperature of more than 1800 ℃ and uses an oxyhydrogen flame for fine processing, it is expensive. However, glass fiber for optical fiber, heat insulation tile, substrate for electronic device, hot air balloon material, chemical apparatus material and UV transmission It is widely used for optical instrument materials and precision springs.

The quartz glass core may be transparent or opaque according to the content of impurities such as Al ₂ O ₃ , Fe ₂ O _3, etc., and the opacity increases as the content of the impurities increases. In addition, according to the embodiment, the quartz glass core may be used without a figure on the surface thereof, or may be used by drawing a refractory zircon figure.

Hereinafter, one embodiment of the method for casting a small diameter hollow casting according to the present invention, which uses a quartz glass core to cast a small diameter hollow casting such as a hollow camshaft, a hollow crankshaft, and the like, is performed as follows.

1. Core Fabrication

A core having the same dimensions as the hollow of a small diameter hollow casting such as a hollow camshaft, hollow crankshaft, etc. to be manufactured is manufactured using quartz glass. The use of a quartz glass core in the casting of hollow castings can produce small diameter hollow castings having a diameter of up to 50 mm.

2. Mold Making

In the green mold or the cell mold, a model of a small diameter hollow casting such as a hollow camshaft, a hollow crankshaft, etc., mainly a wooden mold, is filled with a molding sand, and the model is extracted. In the case of manufacturing a mold, all the steps become simpler.

3. Core installation

The quartz glass core is installed in the lower mold of the mold using a core print having the same diameter and size of the quartz glass core. According to an embodiment, a figure may not be formed on the surface of the quartz glass core, and a refractory zircon figure may be formed.

4. Formation

The molds formed by pouring, pouring, pressing, etc. are covered and molded.

5. Melt injection

After the molding, molten spherical graphite cast iron or gray cast iron is injected through a hot-dip, and in this case, the quartz glass core does not cause sintering due to overheating of the core and is resistant to rapid heat. Since no warpage occurs as in the finished core, a hollow casting of a uniform diameter can be obtained. .

6. Separation of castings

After the molten metal has solidified, the castings are separated from the molds, and the casting sand is removed from the surface. In this case, the sintering phenomenon does not occur after the injection of the melt due to the quartz glass core, so the separation of the molding sand is much easier, and thus a beautiful hollow casting can be obtained.

7. Core spin off and process completed

After the quartz glass core is spun off from the casting, and after finishing, casting of the small diameter hollow casting such as the hollow camshaft and the hollow crankshaft is completed.

Therefore, the casting method of the small diameter hollow castings according to the present invention as described above is molten in the casting of small diameter hollow castings, the diameter of the hollow is smaller than the thickness of the casting and the length of the casting is about 3 times or more of the hollow diameter. It prevents sintering of the core during injection, and has an excellent effect of casting a beautiful hollow casting of a uniform diameter.

Claims (3)

In the conventional method for casting small diameter hollow castings having a diameter smaller than the thickness and having a length of at least three times the diameter of the hollow, A method of casting a small diameter hollow casting, characterized by using a quartz glass core for forming the hollow. The method of claim 1, And the quartz glass core has a SiO ₂ content of 99% or more and an impurity content of 1% or less. The method according to claim 1 or 2, A method of casting a small diameter hollow casting, characterized in that a refractory zircon figure is formed on the surface of the quartz glass core.