AU703642B1 - Riser sleeve with neck-down core - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): YONGSUN YOO Invention Title: RISER SLEEVE WITH NECK-DOWN CORE C.

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*0*4 C. I 4.04 a The following statement is a full description of this invention, including the best method of performing it known to me/us: I I RISER SLEEVE WITH NECK-DOWN CORE BACKGROUND OF THE INVENTION 1) Field of the Invention The present inventiojn relates to a riser sleeve, and more particularly, to a riser sleeve to which a neck-down core is integrated.

2) DescriDtion of Related Arts Generally, a riser sleeve is used in casting cast iron, cast steel, stainless steel and special steels including Mn-steels and Cr-steels. A neck-down core is additionally attached to the bottom of the riser sleeve to make it easier to break off the riser after casting such materials.

U.S. Patent No. 5,299,625 discloses such a riser sleeve, to the bottom of which the neck-down core is attached. The neck-down core is usually made of material that has a relatively high refractoriness and thermal-insulation so that melt can be prevented from being solidified faster than a casting.

However, in the structure of the riser sleeve as described above, since the neck-down core which is manufactured separately is attached to the bottom of the riser sleeve by adhesives, when the attaching portion is damaged or cracked, molten metal flows into a clearance formed by the crack, forming a fin cast. This causes the casting defects. The adhesive used for attaching the neck-down core to the riser sleeve may react with molten metal during the casting process, thereby generating reaction gases.

I r -2- SUMMARY OF THE INVENTION Therefore, the present invention has been made in an effort to solve the above described problems.

IL is an object of the present invention to provide a riser sleeve with which a neck-down core is integrally formed in order to prevent the casting defects.

To achieve the above object, the present invention provides a riser sleeve comprising a sleeve section defining a casting space, and a neck-down core section integrally formed extending from a lower end of the sleeve section. The neck-down core section is provided with an opening having a notch portion formed along with an inner circumference thereof. The neck-down core section is made of at least one material selected from the group consisting of ceramic fiber, silica, alumina, chromite, and zircon.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principle of the invention: Fig. 1 is a sectional view of a riser sleeve with a neck-down core according to a preferred embodiment of the present invention; Fig. 2 is a sectional view of a riser sleeve with a neck-down core according to another preferred embodiment of the present invention; and Fig. 3 is a sectional view of a riser sleeve with a neck-down core according to further preferred embodiment of the present invention.

'4 eBT M -3- DETAILED DESCRIPTION OF TIHE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 shows a riser sleeve with a neck-down core according to a preferred embodiment of the present invention.

The inventive riser sleeve comprises a sleeve section 10 and a neck-down core section 20. The sleeve section 10 can be formed to have a V or U-shape. The neck-down core section 20 is formed as a part of the bottom of the sleeve section 10. An inner wall of the sleeve section 10 defines a molten metal receiving space 12. The neck-down core section 20 is provided with a notch portion 22 formed along with an inner circumference thereof.

The sleeve section 10 is generally made of exthothermic or insulating materials. The neck-down core section is formed of a material which has high refractoriness and thermal-insulation, such as a material, which depends on the cast melt, selected, from the group consisting of i silica, alumina, chromite, and zircon, or a mixture of at least one selected from this group and a ceramic fiber.

S. A method for forming a riser sleeve according to the present .i invention will be described hereinafter.

The neck-down core section 20 is first formed in a predetermined form by mixing the ceramic fiber with phenol resin and alumina, then the sleeve section 10 is formed through, for example, a vacuum process. At this point, a filling material added to the neck-down core section 20 is selected from the group consisting of silica, alumina, chromite, and zircon.

Inorganic or organic binder is used as a binding material. A composition of the inorganic and organic binder also can be used. The inorganic ~-SCI -L -4binder may be selected from the group consisting of silica-sol, alumina-sol, bentonite, and fire clay. The organic binder is selected from the group consisting of drying oils and phenol resins.

After integrally forming the sleeve section 10 and the neck-down core section 20, the same is heat-treated for about 2 hours at 180-2001C.

Therefore, when casting, for example, a high Mn-steel, a riser can be easily removed from the sleeve section by the notch portion 22 of the neck-down core section 20 using a tool such as a small hammer.

Fig. 2 shows another preferred embodiment of the present :invention.

As shown in the drawing, an inner circumference of the neck-down core section 20 can be formed having multi-steps for obtaining notch effect.

In addition, as can be seen from Fig. 3, the neck-down core section 20 according to the present invention may have a projection 24 formed along with an outer circumference thereof. The projection 24 contributes to prevent the riser sleeve 10 from being pushed upward by molding sand when preparing a cast molding or by buoyancy force of molten metal.

In the above described structure of the riser sleeve, since the neck-down core section is integrally formed with the sleeve section, an adhesive for attaching a neck-down core to a sleeve is not required and reaction gas does not produced. Therefore, it is possible to reduce gases defect in casting products. In addition, since there is no possibility of crack of the attaching portion, no cast defects occur, and since no post process for processing fracture is required, the productivity can be increased.

-I I Other embodiments of the invention will be apparent to the slkilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further :features in various embodiments of the invention.

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Claims (3)

1. A riser sleeve comprising: a sleeve section defining a casting space; and a neck-down core section integrally formed with the sleeve section and extending from a lower end of the sleeve section.

2. The riser sleeve of claim 1, wherein the neck-down core section is provided with an opening having a notch portion formed along with an inner circumference of the opening and a projection formed along with an outer circumference of the opening.

3. The riser sleeve of claim 1, wherein the neck-down core section is made of at least one material selected from the group consisting of ceramic fiber, silica, alumina, chromite, and zircon. Dated this 20th day of October, 1998 YONGSUN YOO By his Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia II I I