CASTING SLEEVE WITH WILLIAMS CORE

Abstract

A sleeve (110) for use in metal casting has a sleeve body, where a longitudinal axis (B) has a side wall (116) formed around it, defining a sleeve interior. The sleeve body is open at a first end (118). A core (120) is formed integrally along an interior surface extends into the sleeve interior. The sleeve body and the core are formed of a gas-permeable refractory material. At least the core contains material for generating heat when heated by a molten metal. The core extends along the side wall from the first end to a second end. The core has a width that is constant or decreases in a radial direction away from the side wall, especially with a triangular profile, with a base thereof in contact with the side wall. The sleeve body is cylindrical or frustoconical, with a diameter that decreases from the open first end.

Description

TECHNICAL FIELD

The disclosed embodiments of the present invention relate to sleeves used in the casting of metals. More specifically, the present invention relates to a sleeve that has a “Williams” core provided on an inside length of the sleeve.

BACKGROUND OF THE ART

The so-called “Williams” core owes its name to the work in the 1930's of John Williams of Palmyra, N.Y., as described in U.S. Pat. No. 2,205,327. While that patent speaks for itself and need not be described in any detail here, the core now attributed to Williams is useful to provide a hot spot inside a sleeve used in metal casting. In some circles of the art, the Williams core is referred to as a “firecracker” core.

Sleeves are used in metal casting to provide a reservoir of molten metal during the casting process. As molten metal pours into a mold cavity and solidifies, it shrinks. The failure to replace this metal would result in an undersized piece. Depending upon the size of the piece being cast, it may be necessary to place one or more sleeves in fluid communication with the cavity so that the shrinkage is obviated by the gravity flow of the molten metal in the sleeve into the cavity. In general, a sleeve comprises a material that allows the reservoir of molten metal formed during the pour to remain molten longer than the molten metal entering the mold cavity, so that it is available for flow when needed.

In many instances, the sleeve has a top that is open to the atmosphere. By doing this, the gravity flow into the mold cavity is not opposed by a vacuum being formed at the opposite end of the sleeve. However, this can allow undesired heat loss from the reservoir. This type of a sleeve is often called an “open feeder.”

Also, there are circumstances, especially with a large pour, where the reservoir needs to be positioned low in the mold. In such a case, the reservoir is positioned entirely within the interior of the mold and there is no way provided by the sleeve to counter the vacuum generated by metal flow. These reservoirs are generally referred to as “blind heads.”

In his patent, Williams describes his core as a cylinder or rod of a preferably gas-permeable refractory material that allows communication of the interior of a blind head with the surrounding sand, which is, of course, gas-permeable. In this way, atmospheric pressure is provided into the blind head, and particularly to the interior.

Over time, the Williams core has been refined so that U.S. Pat. No. 4,467,858 to Trinkl says that the Williams core is typically in the shape of a cone or pyramid, with the pointed end extending into the interior of the reservoir. Notably, Trinkl teaches several problems encountered in producing Williams cores integrally with the sleeve or blind head. Even in the invention taught by Trinkl, the Williams core extends inwardly from the cover at the top of the blind feeder sleeve.

Both Williams and Trinkl teach a sleeve that is placed in the mold so that a generally longitudinal axis of the sleeve is aligned vertically in use, with the Williams core at the top.

In some applications, there is a need to allow a sleeve to have its longitudinal axis aligned horizontally when inserted into a mold. One such situation is when the vertical green sand molding technology of DISA Industries (Taalstrup, DK) is being used. These machines use a vertically-split mold and the sleeves are necessarily inserted on their side. One embodiment of such a machine is sold under the registered trademark DISAMATIC. The machine is an automatic production line for fast manufacturing. The need to place the sleeve on its side can arise from a requirement that the sleeve needs to be located at the section of the casting that will be the last to solidify.

It is therefore an unmet advantage of the prior art to provide a casting sleeve having a Williams core that can be effectively used in a horizontal alignment.

SUMMARY OF THE INVENTION

This and other unmet advantages are provided by a sleeve for use in metal casting. The sleeve comprises a sleeve body having a longitudinal axis around which is formed a side wall that defines an interior of the sleeve. The sleeve body is open at a first end thereof. A core is formed integrally along an interior surface of the side wall, extending into the sleeve interior.

In some embodiments, the sleeve body and the core that extends into the sleeve interior are each formed of a gas-permeable refractory material. At least the core will comprise material selected for generating heat when heated by a molten metal.

In many of the embodiments, the core extends along the side wall of the sleeve body from the first end to a second end thereof. Such a core will have a width that is constant or decreases in a radial direction away from the side wall. Such a decreasing width is provided by a core that has a triangular profile, with a base thereof in contact with the side wall.

In many embodiments, the sleeve body is frustoconical, with a diameter that decreases from the open first end to a second end thereof. The second end of the sleeve body may be open or closed. In case where it is open, it may be closable with a cover, sized and adapted to close the sleeve body at a second end thereof. In some cases, the cover may be formed integrally with the sleeve body at the second end.

The cover, when provided, may be provided with at least one aperture therethrough. Such a cover would comprise a gas-permeable refractory material and, optionally, material selected for generating heat when heated by a molten metal. Preferably, these would be the same materials as the sleeve body and core.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the disclosed embodiments will be obtained from a reading of the following detailed description and the accompanying drawings wherein identical reference characters refer to identical parts and in which:

FIG. 1 is a side sectional view of a blind feeder sleeve with a Williams core, as known in the prior art;

FIG. 2 is a side sectional view of an exemplary embodiment of a sleeve having a Williams core, arranged in the same manner as the FIG. 1 sleeve; and

FIG. 3 is a perspective view of a section of the FIG. 2 embodiment sleeve, rotated to show the sleeve with a longitudinal axis arranged horizontally.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 shows a side-sectional view of a typical blind feeder sleeve 10 with a Williams core 12, in the manner generally taught by Trinkl in the prior art. This sleeve 10 has the Williams core 12 integrally formed as a part of the cover 14. The sleeve 10 has a longitudinal axis A, with a side wall 16 that is preferably symmetrical about the axis. In the depicted embodiment, the side wall 16 appears to be somewhat frustoconical, with the larger diameter at the open lower end 18. However, it would also be known to provide a cylindrical sidewall 16. The blind feeder sleeve 10 is arranged with the axis A aligned in a vertical direction, facilitating outflow through open lower end 18 of the molten metal contained therein. Although not shown in FIG. 1, it would be known to provide one or more vent apertures through cover 14 to enhance the gas-permeability of the material comprising the sleeve 10.

If the FIG. 1 embodiment 10 were to be placed in a mold with the axis A aligned in a horizontal manner (rather than the illustrated vertical manner), the beneficial effect of the Williams core 12 would be lost.

FIG. 2 shows, in side-sectional view, an embodiment that incorporates the concept of a Williams core for a feeder sleeve 110 that can be used with effect in a horizontal position. The sleeve 110 has a cover 114 and a side wall 116. As in the prior art example provided in FIG. 1, and subject to an exception required by the Williams core that will be described, the side wall 116 is designed for symmetry about a longitudinal axis. In this case, the axis is designated as B. To facilitate comparison with the prior art, the sleeve 110 in FIG. 2 is shown in the same orientation as the FIG. 1 sleeve. It can thus be seen that the side wall 116 can have a frustoconical or cylindrical design. The cover 114, which is needed in the prior art to provide a base for the Williams core, is not needed for that purpose in the FIG. 2 sleeve 116. Opposite the cover 114 is an open end 118, which is substantially the same as the open lower end 18 of the FIG. 1 prior art. The cover 114 can be either formed integrally with the sidewall 116 or it can be separately formed in a size to fit into an otherwise open second end of the sleeve 110.

While continuing to consider FIG. 2, FIG. 3 is now introduced as a section view of the FIG. 2 embodiment 110 that allows a view down the longitudinal axis B. In these views, it is readily seen that a portion 120 of the side wall 116 has been formed to project in a radial direction into the interior of the sleeve 110. As shown, the portion 120 extends in the longitudinal direction essentially from the cover 114 to the open end 118. In the depicted embodiment, the portion 120 is shaped as a wedge, with the larger base of the wedge formed along the side wall 116. The portion 120 need not be a wedge, but it is preferred for the portion to have a constant profile along the entire length that extends from the cover 114 to the open end 118. The portion 120 also does not need to decrease in width in the manner shown in FIGS. 2 and 3, but it is preferred that the width does not increase as one moves from the side wall towards the longitudinal axis.

When the portion 120 that exemplifies the features of a Williams core is integrally formed during manufacture of the sleeve 110, it will have essentially the same properties of gas-permeability, exothermicity, etc. as that provided by the side wall 116 of the sleeve. However, the projection of the portion 120 into the interior space defined by the side wall 116 provides the improvement over a sleeve lacking the Williams core structure.

As also seen in FIGS. 2 and 3, the cover may be provided with one or more vent apertures 122. In the embodiment of FIGS. 2 and 3, there are two vent apertures 122 provided and they are placed near the portion 120.

When placed into a sand mold where the longitudinal axis needs to be arranged horizontally, the preferred orientation for the embodiment 110 is shown in FIG. 3. In this situation, the portion 120 is positioned at the “top” or “12 o'clock” position, so that it is gravitationally above the molten metal reservoir formed in the sleeve 110 by the pour.

Claims

1. A sleeve for use in metal casting, comprising: a sleeve body having a longitudinal axis around which is formed a side wall that defines an interior of the sleeve, the sleeve body being open at a first end thereof; anda core, formed integrally along an interior surface of the side wall and extending into the sleeve interior.

2. The sleeve of claim 1, wherein: the sleeve body and the core that extends into the sleeve interior are each formed of a gas-permeable refractory material.

3. The sleeve of claim 2, wherein: at least the core comprises material selected for generating heat when heated by a molten metal.

4. The sleeve of claim 1, wherein: the core extends along the side wall of the sleeve body from the first end to a second end thereof.

5. The sleeve of one of claim 1, wherein: the core has a width that is constant or decreases in a radial direction away from the side wall.

6. The sleeve of claim 5, wherein: the core has a triangular profile, with a base thereof in contact with the side wall.

7. The sleeve of claim 1, wherein: the sleeve body is frustoconical, with a diameter that decreases from the open first end to a second end thereof.

8. The sleeve of claim 1, further comprising: a cover, sized and adapted to close the sleeve body at a second end thereof.

9. The sleeve of claim 1, further comprising, a cover, formed integrally with the sleeve body at a second end thereof.

10. The sleeve of claim 9, wherein: the cover is provided with at least one aperture therethrough.

11. The sleeve of claim 9, wherein: the cover comprises a gas-permeable refractory material and, optionally, material selected for generating heat when heated by a molten metal.

12. The sleeve of claim 8, wherein: the cover is provided with at least one aperture therethrough.

13. The sleeve of claim 8, wherein: the cover comprises a gas-permeable refractory material and, optionally, material selected for generating heat when heated by a molten metal.

14. The sleeve of claim 3, wherein: the core extends along the side wall of the sleeve body from the first end to a second end thereof.

15. The sleeve of claim 3, wherein: the core has a width that is constant or decreases in a radial direction away from the side wall.

16. The sleeve of claim 15, wherein: the core has a triangular profile, with a base thereof in contact with the side wall.

17. The sleeve of claim 3, wherein: the sleeve body is frustoconical, with a diameter that decreases from the open first end to a second end thereof.

18. A sleeve for use in metal casting, comprising: a sleeve body having a longitudinal axis around which is formed a side wall that defines an interior of the sleeve, the sleeve body being frustoconical, with a diameter that decreases from an open first end to a second end thereof; anda core, formed integrally along an interior surface of the side wall and extending into the sleeve interior, the core having a triangular profile, with a base thereof in contact with the side wallwherein each of the sleeve body and the core are formed of a gas-permeable refractory material, with at least the core further comprising material selected for generating heat when heated by a molten metal.

19. A method of preparing a mold for casting a molten metal, comprising the steps of: providing a sleeve according to claim 1;providing a vertically-split mold;inserting the sleeve in a first part of the vertically-split mold, such that an axis of the sleeve lies horizontally in the mold when the mold is oriented to receive the molten metal, with the core of the sleeve positioned to be gravitationally above a reservoir of the molten metal reservoir formed in the sleeve by a pour of the molten metal.