GB2550944A

GB2550944A - Feeder system

Info

Publication number: GB2550944A
Application number: GB1609626.5A
Authority: GB
Inventors: Viktorovich Soloveykin Anton
Original assignee: Foseco International Ltd
Current assignee: Foseco International Ltd
Priority date: 2016-06-02
Filing date: 2016-06-02
Publication date: 2017-12-06
Also published as: RU178745U1; CN207642240U; GB201609626D0

Abstract

A feeder system 100 for metal casting comprises a feeder sleeve 102 comprising a closed first end 106, an open second end 108 and a continuous sidewall 110 therebetween and a substantially planar breaker core 104 mounted on the second end of the feeder sleeve and having an aperture 116 therethrough, the aperture being offset from the centre of the breaker core, the feeder sleeve and the breaker core together defining a closed cavity for containing molten metal and the breaker core being provided with at least one retaining element 118 for holding and suspending the feeder system on a mould pattern. The retaining element preferably comprises a loop or hook of metal, wire or plastic. Also disclosed is a moulding system (500, figure 5a) for preparing a mould for metal casting comprising the feeder system 100 of the invention and a pin 508 received by the retaining element of the feeder system. Further disclosed is a method for preparing a horizontally parted mould for metal casting using said feeder system.

Description

Feeder system

The present invention relates to a feeder system for use in metal casting operations utilising casting moulds, and a moulding system comprising the feeder system.

In a typical casting process, molten metal is poured into a pre-formed mould cavity which defines the shape of the casting. However, as the metal solidifies it shrinks, resulting in shrinkage cavities which in turn result in unacceptable imperfections in the final casting. This is a well-known problem in the casting industry and is addressed by the use of feeder sleeves or risers which are integrated into the mould either during mould formation (ram-up sleeves) or inserted afterwards (insert sleeves). Each feeder sleeve provides an additional (usually enclosed) volume or cavity which is in communication with the mould cavity, so that molten metal also enters into the feeder sleeve. During solidification, molten metal within the feeder sleeve flows back into the mould cavity to compensate for the shrinkage of the casting. It is important that metal in the feeder sleeve cavity remains molten longer than the metal in the mould cavity, so feeder sleeves are made to be highly insulating or more usually exothermic, so that upon contact with the molten metal additional heat is generated to delay solidification.

The feeder sleeve may be located above the mould cavity (commonly known as a ‘top feeder1), or it may be located next to the mould cavity (known as a ‘side feeder’). During preparation of the mould, top feeders may be placed on top horizontal surfaces of the mould pattern, such that they are in direct contact with the casting surface. Alternatively, side feeders may be positioned above ingates connecting a running system to the casting cavity, or above a feeder base and neck area, all of which are horizontally connected to the mould cavity. Due to their different solidification properties and feed requirements, steel castings generally require a shorter metal flow path from the feeder compared to iron castings, resulting in the need to have multiple risers distributed around the casting.

After solidification of the casting and removal of the mould material, unwanted residual metal from within the feeder sleeve cavity remains attached to the casting and must be removed. In order to facilitate removal of the residual metal, the feeder sleeve cavity may be tapered towards its base (i.e. the end of the feeder sleeve which will be closest to the mould cavity) in a design commonly referred to as a neck down sleeve. When a sharp blow is applied to the residual metal it separates at the weakest point which will be near to the mould (the process commonly known as “knock off”). A small footprint on the casting is also desirable to allow the positioning of feeder sleeves in areas of the casting where access may be restricted by adjacent features.

Although feeder sleeves may be applied directly onto the surface of the casting mould cavity, they are often used in conjunction with a feeder element (also known as a breaker core). A breaker core is simply a disc of refractory material (typically a resin bonded sand core or a ceramic core or a core of feeder sleeve material) with a hole, usually in its centre, which sits between the mould cavity and the feeder sleeve. The diameter of the hole through the breaker core is designed to be smaller than the diameter of the interior cavity of the feeder sleeve (which need not necessarily be tapered) so that knock off occurs at the breaker core close to the casting surface. To further assist knock off, the bore of the breaker core is often profiled such that it forms a V-shaped notch in the metal feeder neck.

In some instances there may be dimensional limitations in the moulding box in which the mould is prepared, so that there is not sufficient height to place a top feeder. Although the use of an ingate or a side feeder circumvents the need for a top feeder, an ingate increases the distance between the mould cavity and the feeder sleeve, and thus increases the volume of metal required.

The present invention has been devised with these issues in mind.

According to a first aspect of the present invention there is provided a feeder system for metal casting comprising: a feeder sleeve comprising a closed first end, an open second end and a continuous sidewall therebetween; and a substantially planar breaker core mounted on the second end of the feeder sleeve and having an aperture therethrough, said aperture being offset from the centre of the breaker core, the feeder sleeve and the breaker core together defining a closed cavity for containing molten metal, except for the aperture in the breaker core, wherein the breaker core is provided with at least one retaining element for supporting the feeder system on a mould pattern.

It will be understood that any statements made in relation to the first aspect of the invention also apply to the second and/or third aspects, as appropriate, and vice versa.

In some embodiments the breaker core is provided with a single retaining element. Alternatively, the breaker core may be provided with more than one retaining element. In some embodiments, the breaker core is provided with at least two or at least three retaining elements.

In some embodiments, the second end of the feeder sleeve is beveled such that the longitudinal axis of the feeder sleeve is inclined by less than 90° relative to the plane of the breaker core. In said embodiments it will be understood that, with the breaker core supported on a vertical surface of the mould pattern, the feeder sleeve will be inclined such that the closed first end is higher than the open second end, thereby assisting feeding and minimising the unusable reservoir of molten metal below the aperture in the feeder cavity.

In some embodiments, the longitudinal axis of the feeder sleeve is substantially perpendicular to the plane of the breaker core.

In some embodiments, the retaining element comprises a projection extending generally away from the feeder sleeve, the projection having a bore therein whose axis is parallel to the plane of the breaker core. The bore may be a blind bore (i.e. having a single opening in a side of the projection) or a through bore (i.e. extending all the way through the projection from one side to another).

In some embodiments the projection comprises an abutment surface, the bore extending from said surface. In use, the abutment surface is received on a surface of the mould pattern. The abutment surface may be planar or it may be shaped (e.g. curved). For example, the abutment surface may be shaped in accordance with the shape of a corresponding surface of the mould pattern on which the abutment surface is intended to be seated.

In some embodiments the retaining element comprises a loop or a hook of metal, wire or plastic, the end or ends of which pass into or through the breaker core and are anchored therein.

It will be appreciated that the number of retaining elements and their configuration will be selected by the skilled person in accordance with the size of the feeder system and, more importantly, the weight of the feeder system once the feeder sleeve is at least partly filled with molten metal. In particular, the size and shape of the projection and the bore therein will be determined by the size and weight of the feeder sleeve that must be supported.

In some embodiments, the height of the projection, measured parallel to the plane of the breaker core is from 20% to 150%, from 30% to 130%, from 40% to 110% or from 50% to 90% of the distance that the projection extends away from in a direction perpendicular to the plane of the breaker core.

In some embodiments, the projection has a height that is from 5% to 70%, from 15% to 60% or from 25% to 50% of the height of the breaker core, both heights being measured in the same direction parallel to the plane of the breaker core. A relative height of at least 30% or at least 40% may be beneficial for larger feeder systems and/or feeder systems having a high density.

It will be appreciated that the greater the length of the bore, the greater the support given to the feeder system. Thus, in some embodiments the bore has a height that is from 60% to 100%, or from 70% to 90% of the height of the projection, both heights being measured in the same direction parallel to the plane of the breaker core.

The feeder sleeve may be any suitable size and shape. In some embodiments, the feeder sleeve is substantially circular or oval in cross section. In other embodiments, the feeder sleeve is substantially square, rectangular or triangular or irregular in cross section.

In some embodiments, the feeder sleeve is substantially cylindrical.

In embodiments wherein the second end of the feeder sleeve is beveled, it will be appreciated that the distance between the first and second ends of the feeder sleeve varies from a minimum length in a first region to a maximum length in a second region of the sidewall. In such embodiments, the breaker core may be mounted on the feeder sleeve such that the aperture is closer to the second region of the sidewall than to the first region. When the feeder system is in an in-use orientation, the first region may correspond to an upper region of the sidewall, while the second region may correspond to a lower region of the sidewall. Thus, in some embodiments, the aperture may be located closer to or adjacent a lower region of the sidewall, in use. The positioning of the aperture towards the lower region of the sidewall (in use) maximizes the volume of metal that can be released from the cavity of the feeder sleeve into the mould cavity, and minimizes the volume of the reservoir of unusable metal below the aperture. In some embodiments, the retaining element is located between the aperture and the first region of the sidewall. In other words, in an in-use orientation the retaining element may be located above the aperture.

In some embodiments the longitudinal axis of the feeder sleeve is inclined at an angle of from 30° to 90°, from 35° to 70°, or from 40° to 50° (e.g. approximately 45°) relative to the plane of the breaker core. An angled feeder sleeve aids the flow of metal from the cavity of the feeder system into the mould cavity under the influence of gravity.

In some embodiments a Williams Wedge is included inside the feeder sleeve. This can be either an insert or preferably an integral part produced during the forming of the sleeve, and comprises a prism shape situated on the internal roof of the sleeve. On casting when the sleeve is filled with molten metal, the edge of the Williams Wedge ensures atmospheric puncture of the surface of the molten metal and release of the vacuum effect inside the feeder to allow more consistent feeding.

The feeder sleeve of the present invention may be formed from or comprise any suitable refractory insulating and/or exothermic material or composition from which known feeders may be formed; the skilled person will be able to select the appropriate materials for each particular requirement. The nature of the feeder sleeve material is not particularly limited and it may be for example insulating, exothermic or a combination of both. Neither is its mode of manufacture particularly limited, it may be manufactured for example using either the vacuum-forming process or core-shot method. Typically, a feeder sleeve is made from a mixture of low and high density refractory fillers (e.g. silica sand, olivine, alumino-silicate hollow microspheres and fibres, chamotte, alumina, pumice, perlite, vermiculite) and binders. An exothermic sleeve further requires a fuel (usually aluminium or aluminium alloy), an oxidant (typically iron oxide, manganese dioxide, or potassium nitrate) and usually initiators/sensitisers (typically cryolite).

The feeder sleeve may be formed by any of the known methods of forming feeders, for example by vacuum forming a slurry of the sleeve material around a former and inside an outer mould, followed by heating of the sleeve to remove the water and to harden or cure the material. Alternatively, the feeder sleeve may be formed by ramming or blowing the material in a core box (core shot method), and curing the sleeve via the passage of a reactive gas or catalyst through the sleeve to cure the binder, or via application of heat by using a heated core box, or by removing the sleeve and heating in an oven. Suitable feeder compositions include for example those sold by Foseco under the trade name KALMIN and KALMINEX, made by both slurry and core-shot methods.

The density of the feeder sleeve depends on both the composition and method of manufacture. In some embodiment, the density of the feeder is no more than 1.5 g cm'3, no more than 1.0 g cm'3 or no more than 0.7 g cm'3. In some embodiment, the density of the feeder is from 0.8 to 1.0 g cm'3 or from 0.5 to 0.7 g cm'3.

The breaker core is designed to reduce the feeder to casting contact area and may typically be based on silica or sometimes chromite sand, produced by blowing novolak resin coated sand into a heated core box allowing the resin to melt then harden (Croning process). Alternatively, the breaker core may be made from highly refractory ceramic material or shaped metal such as steel plate.

The breaker core and the retaining element may be formed from the same material, or they may be formed from different materials. In some embodiments the retaining element is integrally formed with the breaker core.

The thickness of the breaker core will partly depend on the size of the feeder, and a typical sand breaker core will have a thickness of the order 8 to 15 mm, whereas a ceramic breaker core being stronger will typically have a thickness of 5 to 10 mm. The breaker core is mounted on the feeder sleeve and fixed by adhesive, typically a hot melt glue.

According to a second aspect of the present invention there is provided a moulding system for preparing a mould for metal casting, the moulding system comprising: a horizontal planar surface; a mould pattern seated on the horizontal planar surface, the mould pattern having a vertical planar surface and an upper surface; a pin extending vertically upwardly from the upper surface; and the feeder system of the first aspect of the invention, wherein the pin is received by the retaining element such that at least a part of the breaker core containing the aperture is flush with the vertical planar surface of the mould pattern and the retaining element is seated on the upper surface.

In some embodiments the abutment surface of the projection is seated on the upper surface of the mould pattern. In some embodiments the abutment surface is planar. In some embodiments the abutment surface is shaped in accordance with the shape of the upper surface of the mould pattern on which the abutment surface is intended to be seated. For example, a planar abutment surface is seated on a corresponding planar upper surface of the mould pattern. Alternatively, the abutment surface may be curved to match the curvature of a curved upper surface.

The pin may have a height which is from 50% to 400% of the height of the bore in the projection. In some embodiments wherein the bore is a blind bore, the pin has a height which is from 50% to 100%, from 60% to 90% or from 70% to 80% of the height of the bore . In some embodiments wherein the bore is a through bore, the pin has a height which is from 70% to 400%, from 100% to 300% or from 150% to 250%of the height of the bore. In general, larger and heavier feeder systems require a longer bore and consequently require a longer pin for support.

The pin may be formed from any suitable material. In some embodiments, the pin is formed from a metal. The pin may be fixed to the upper surface of the mould pattern by any suitable means. In some embodiments, the pin is screwed into the upper surface.

The mould pattern may be formed from any suitable material, such as wood.

According to a third aspect of the invention there is provided a process for preparing a horizontally parted mould for metal casting comprising: placing a mould pattern on a horizontal planar surface with the mould pattern orientated to have a vertical planar surface and an upper surface from which a pin extends vertically upwardly; placing the feeder system of the first aspect of the invention on the mould pattern such that the pin is received within the retaining element and at least a part of the breaker core containing the aperture is flush with the vertical planar surface of the mould pattern; surrounding the mould pattern and the feeder system with mould material; compacting the mould material; removing the mould pattern, together with the pin, from the compacted material to form an upper half (cope) mould.

The method may also comprise preparing a lower half (drag) mould in a similar manner to the upper half mould without the use of a feeder system.

The method may further comprise placing the cope mould on top of the drag mould.

The present invention thus provides a side feeder which can be supported on a mould pattern by virtue of a breaker core which is provided with at least one retaining element. In use, the feeder system is placed on a mould pattern such that the pin, which extends vertically upwardly from an upper surface of the mould pattern, is received within the retaining element of the breaker core. Since the breaker core is substantially planar, it rests and is held against the mould pattern during preparation of the mould and, on removal of the mould pattern, the aperture of the breaker core is in direct contact with the casting cavity. By reducing the distance between the cavity of the feeder system and the casting cavity, the amount of waste metal upon removal of the feeder system from the finished casting is reduced.

It will be appreciated that the pin must extend substantially vertically from the upper surface of the mould pattern, and that the bore within the projection which receives the pin must also extend parallel to the plane of the breaker core such that, on removal of the mould pattern and pin from the compacted mould material, the pin slides out of the bore without either damaging the breaker core or pulling out the feeder system.

The mould material may be moulding sand. As is well-known in the art, moulding sand can be classified into two main categories; chemical bonded (based on either organic or inorganic binders) or clay-bonded. Chemically bonded moulding sand binders are typically self-hardening systems where a binder and a chemical hardener are mixed with the sand and the binder and hardener start to react immediately, but sufficiently slowly enough to allow the sand to be shaped around the pattern plate and then allowed to harden enough for removal and casting. Clay-bonded moulding systems use clay and water as the binder and can be used in the “green” or undried state and are commonly referred to as greensand. Greensand mixtures do not flow readily or move easily under compression forces alone and therefore to compact the greensand around the pattern and give the mould sufficient strength properties, a variety of combinations of jolting, vibrating, squeezing and ramming are applied to produce uniform strength moulds at high productivity.

Moulding practices are well known and are described for examples in chapters 12 and 13 of Foseco Ferrous Foundryman’s Handbook (ISBN 075064284 X). A typical process known as the no-bake or cold-setting process is to mix the sand with a liquid resin or silicate binder together with an appropriate catalyst, usually in a continuous mixer. The mixed sand is then compacted around the pattern by a combination of vibration and ramming and then allowed to stand, during which time the catalyst begins to react with the binder resulting in hardening of the sand mixture. When the mould has reached a handleable strength, it is removed from the pattern and continues to harden until the chemical reaction is complete.

In some embodiments the mould material is chemical bonded sand, for example sand which is bonded by a no-bake cold-setting process which uses a liquid binder such as an acid set furanic or phenolic resin, or an ester set alkaline phenolic or sodium silicate binder together with an appropriate catalyst. In some embodiments, the mould material is clay bonded sand (greensand). This typically comprises a mixture of clay such as sodium or calcium bentonite, water and other additives such as coal dust and cereal binder.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:-

Figure 1a is a perspective view of a feeder system in accordance with an embodiment of the invention;

Figure 1 b is a side view of the feeder system of Figure 1 a;

Figure 1 c is a plan view of the feeder system of Figure 1 a;

Figure 2 is a perspective view of a feeder system in accordance with an alternative embodiment of the invention;

Figure 3 is a perspective view of a feeder system in accordance with another embodiment of the invention;

Figure 4a is an front end-on front view of a breaker core in accordance with an alternative embodiment of the invention;

Figure 4b is a perspective rear view of the breaker core of Figure 4a;

Figure 5a is a feeder system in accordance with an embodiment of the invention in use during the process of preparing a casting mould; and

Figure 5b is a feeder system according to an embodiment of the invention in use during the process of casting a metal article.

Referring to Figures 1a-c, there is shown a feeder system 100 according to a first aspect of the invention, comprising a feeder sleeve 102 and a breaker core 104.

The feeder sleeve 102 comprises a closed first end 106, an open second end 108 and a continuous sidewall 110 therebetween. The basic shape of the feeder sleeve is that of a (hollow) cylindrical segment in which the closed end 106 defines a circular cap and the open end 108 defines an elliptical cap. The distance between the first end 106 and second end 108 of the feeder sleeve 102 varies continuously from a minimum length A in a first (upper in use) region 112 of the sidewall 110 to a maximum length B in a second (lower in use) region 114 of the sidewall 110.

The breaker core 104 has an elliptical, substantially planar portion 104a with an aperture 116 therethrough, the periphery of the planar portion corresponding to the second end 108 of the feeder sleeve 102. The side wall of the aperture has an inwardly projecting V-shaped profile, the sharp edge 117 providing a notch in the feeder neck to further assist knock off. The breaker core 104 is integrally formed with a retaining element in the form of a generally cuboidal projection 118 having radiused corners at its free end 120 and which is located centrally on and projects away from the planar portion 104a of the breaker core 104.

The projection 118 comprises substantially planar, non-parallel, lower surface 122 and upper 124 surface such that the projection 118 tapers slightly towards its free end 120 and a circular through bore 126 extending from the lower 122 to upper 124 surface in the region of the free end 120 of the projection, the axis of the bore 126 being parallel to the planar portion 104a. In use, the lower surface 122 of the projection 118 constitutes an abutment surface for being received on an upper surface of a mould pattern.

The height of the projection 118 is approximately 10% of the height of the breaker core 104, and approximately 35% of the distance that the projection 118 extends in a perpendicular direction away from the plane of the breaker core 104.

The planar portion 104a of the breaker core 104 is attached to the open end 108 of the feeder sleeve 102 by adhesive such that the projection 118 faces away from the sleeve 102 and the aperture is located adjacent the second lower region 114 of the sidewall 110. The segmenting or bevelling of the cylindrical feeder sleeve at its second end results in the longitudinal axis (L) of the feeder sleeve 102 being inclined by an angle a, approximately 50°, relative to the plane (P) of the breaker core 104. It will be understood that the feeder sleeve 102 and breaker core 104 define a substantially closed cavity for molten metal in use, the only entrance to and exit from the cavity being the aperture 116 in the breaker core 104.

Referring to Figure 2, there is shown an alternative embodiment of a feeder system 200 substantially the same as shown in Figure 1. The feeder sleeve is identical to that of figure 1 and corresponding parts of the breaker core 204 are labelled in the “200” series. The projection 218 of the breaker core 204 is thickened in a direction parallel to the axis of the bore 226 compared to the embodiment of Figure 1 and the upper surface 224 of the projection 218 flares upwardly in a curve at its point of intersection with the substantially planar portion 204a.

Referring to Figure 3, there is shown another embodiment of a feeder system 300 substantially the same as shown in Figure 1. The feeder sleeve is identical to that of figure 1 and corresponding parts of the breaker core 304 are labelled in the “300” series. In this embodiment the projection 318 of the breaker core 304 is thickened in a direction parallel to the axis of the bore 326 to the extent that the upper surface is flush with the peripheral edge of the planar portion 304a of the breaker core 304 and is generally curved in line with the peripheral edge of the breaker core 304. The height of the projection 318 is approximately 50% of the height of the breaker core 304 measured parallel to the axis of the bore 326 in the projection 318. In this case the bore 326 (shown in dashed lines) extends from the lower surface 322 into the projection but not as far as the upper surface 324 (i.e. a blind bore).

Referring to Figures 4a and 4b, there is shown an alternative embodiment of a breaker core 404 for use with a feeder system of the present invention. Corresponding parts of the breaker core 404 are labelled in the “400” series. The breaker core 404 has the same elliptical planar portion 404a as the previous embodiments and an aperture 416. The breaker core 404 is provided with a pair of mutually spaced parallel slots 430 which lie on a central axis of the breaker core 404. Two retaining elements 432 are provided each in the form of a metal spring clip having a looped central portion 432a, a waisted region and free ends 432b which curve outwardly away from each other and then back towards the looped central portion 432a. The clips are mounted to the breaker core 404 by inserting the looped central portion 432a through the slots 430 in the breaker core 404 so that the waisted region lies within the slot 430. Accidental dislodgement of the retaining means 432 is prevented in one direction by the natural resilience of the spring clip preventing the looped portion 432a passing back through the slot 430 and in the other direction by abutment of the free ends 432b on the breaker core 404 either side of the slot 430. It will be understood that, as with the slots 430, the loops 432a are axially aligned so that in use they can receive a pin.

Referring to Figure 5a, there is shown half of a moulding system 500 according to a second aspect of the invention comprising: the feeder system 100 of figure 1, a mould pattern 502 for an upper part of a valve housing having a planar vertical end surface 504 and an upper surface 506, and a metal pin 508 extending vertically upwardly from the upper surface 506 of the mould pattern 502. The mould pattern 502 also includes internal cores (not shown) to provide flow passages within the casting and spot feeders (not shown) of standard design as will be familiar to the skilled person. The mould pattern 502 is formed from wood into which the pin 508 is screwed.

The feeder system 100 is mounted on the mould pattern 502 by sliding the bore of the projection 118 over the pin 508 such that the lower part of the breaker core 104 containing the aperture 116 lies flush against and in direct contact with the planar vertical surface 504 of the mould pattern 502 and the feeder sleeve 102 overhangs the side of the pattern 502. The abutment surface of the projection 118 is seated on the upper surface 506 of the mould pattern 502. It will be understood that this arrangement is extremely stable: rotational movement of the feeder system 100 is prevented by abutment of the planar portion of the breaker core 104 with the planar vertical surface 504 of the mould pattern 502.

During a process for preparing a horizontally parted mould for metal casting, the mould assembly is positioned on a horizontal pattern plate 510. The mould assembly is surrounded with mould material 512, which is then compacted and hardened. The horizontal pattern plate 510 and the mould pattern 502 are removed from the compacted mould material 512, leaving a half mould cavity 514a (see Figure 5b) which is the inverse shape of the mould pattern 502. The feeder system 100 remains embedded in the compacted mould material 512. The axis of the bore through the projection 118 being parallel to the plane of the breaker core 104 allows the pin 508 to be easily removed from the projection 118 without disturbing or breaking the feeder system 100 within the compacted mould material. Removal of the pin creates a small cavity 514c.

Referring to Figure 5b, there is shown a mould 516 assembled and ready for casting. The mould 516 comprises an upper (cope) mould part 518a, formed from the mould assembly shown in Figure 5a, and a lower (drag) mould part 518b, formed in a similar manner but without a feeder system. The cope mould contains two additional standard top feeders 530. The cope mould 518a and the drag mould 518b are formed with a downsprue 520, runner system 522 and ingates 524. Half mould cavities 514a and 514b constitute the mould cavity 514, wherein the line X—X represents the horizontal parting line of the mould. The aperture 116 in the breaker core 104 of the feeder system 100 is in direct communication with the mould cavity 514.

During a metal casting process, molten metal is poured into the mould 516 via the downsprue 520, through the runner system 522 and ingates 524. Molten metal fills the mould cavity 514 and also enters the feeder system 100 through the aperture 116 in the breaker core 104, and the feeder system 530 through the aperture in its breaker core (not shown). As the metal in the mould cavity 514 solidifies and contracts, molten metal within the feeder sleeve 102 flows back into the mould cavity 514 through the aperture 116, compensating for the shrinkage and ensuring that the cast fills the mould cavity 514 completely when cooled. The inclined angle of the feeder sleeve 102 assists in feeding molten metal into the mould cavity 514 through the aperture 116 in the breaker core 104. The location of the aperture 116 close to the lower region of the feeder sleeve 102 minimises the unusable reservoir of metal below the aperture 116, reducing wastage.

Claims

1. A feeder system for metal casting comprising: a feeder sleeve comprising a closed first end, an open second end and a continuous sidewall therebetween; and a substantially planar breaker core mounted on the second end of the feeder sleeve and having an aperture therethrough, said aperture being offset from the centre of the breaker core, the feeder sleeve and the breaker core together defining a closed cavity for containing molten metal, except for the aperture in the breaker core, and wherein the breaker core is provided with at least one retaining element for holding and suspending the feeder system on a mould pattern.

2. The feeder system of claim 1, wherein the second end of the feeder sleeve is beveled such that the longitudinal axis of the feeder sleeve is inclined by less than 90° relative to the plane of the breaker core.

3. The feeder system of claim 1 or claim 2, wherein the retaining element comprises a projection extending generally away from the feeder sleeve, the projection having a bore therein whose axis is parallel to the plane of the breaker core.

4. The feeder system of claim 3, wherein the bore is a blind bore or a through bore.

5. The feeder system of claim 3 or claim 4, wherein the projection comprises an abutment surface, the bore extending from said surface.

6. The feeder system of claim 5, wherein the abutment surface is planar.

7. The feeder system of any one of claims 3 to 6, wherein the height of the projection, measured parallel to the plane of the breaker core is from 30% to 150% of the distance that the projection extends away from in a direction perpendicular to the plane of the breaker core.

8. The feeder system of any one of claims 3 to 7, wherein the projection has a height that is from 5% to 70% of the height of the breaker core, both heights being measured in the same direction parallel to the plane of the breaker core.

9. The feeder system of any one of claims 3 to 7, wherein the bore has a height that is from 60% to 100% of the height of the projection, both heights being measured in the same direction parallel to the plane of the breaker core.

10. The feeder system of any preceding claim, wherein the retaining element is integrally formed with the breaker core.

11. The feeder system of any preceding claim, wherein the feeder sleeve or feeder system is substantially circular or oval in cross section.

12. The feeder system of any preceding claim, wherein the longitudinal axis of the feeder sleeve is inclined at an angle of from 35° to 70° relative to the plane of the breaker core.

13. The feeder system of claim 1 or claim 2, wherein the retaining element comprises a loop or hook of metal, wire or plastic, the end(s) of which pass through the breaker core and are anchored therein.

14. The feeder system of any preceding claim, further comprising a Williams Wedge located inside the feeder sleeve.

15. A moulding system for preparing a mould for metal casting, the moulding system comprising: a horizontal planar surface; a mould pattern seated on the horizontal planar surface, the mould pattern having a vertical planar surface and an upper surface; a pin extending vertically upwardly from the upper surface; and the feeder system of any one of claims 1 to 14, wherein the pin is received by the retaining element such that at least a part of the breaker core containing the aperture is flush with the vertical planar surface of the mould pattern and the retaining element is seated on the upper surface.

16. The moulding system of claim 15 comprising the feeder system of claim 4, wherein the abutment surface of the projection is seated on the upper surface of the mould pattern.

17. The moulding system of claim 16, wherein the abutment surface is planar and is seated on a corresponding planar upper surface of the mould pattern.

18. The moulding system of any one of claims 15 to 17, comprising the feeder system of any one of claims 3 to 9, wherein the pin has a height which is from 50% to 400% of the height of the bore in the projection.

19. A process for preparing a horizontally parted mould for metal casting comprising: placing a mould pattern on a horizontal planar surface with the mould pattern orientated to have a vertical planar surface and an upper surface from which a pin which extends vertically upwardly; placing the feeder system of any one of claims 1 to 14 on the mould pattern such that the pin is received within the retaining element and at least a part of the breaker core containing the aperture is flush with the vertical planar surface of the mould pattern; surrounding the mould pattern and the feeder system with mould material; compacting the mould material; removing the mould pattern, together with the pin, from the compacted material to form an upper half mould; preparing a lower half mould in a similar manner to the upper half mould without the use of a feeder system; and placing the upper half mould on top of the lower half mould.

20. A feeder system substantially as described herein with reference to Figures 1-4.

21. A moulding system substantially as described herein with reference to Figure 5a.

22. A process for preparing a horizontally parted mould for metal casting substantially as described herein with reference to Figure 5b.