Assembly for casting molten metal including a sand casting mold, a short shroud, and a mold / shroud coupling mechanism, casting apparatus, and method for casting molten metal parts

Abstract

The present invention relates to a kit and assembly of parts, including a sand casting mold (2) for casting a metal part, a short shroud (9) with a short shaft (10), and a mold / shroud coupling mechanism (14). The mold (2) includes a bore (7) extending over a bore length (d7) from a bore inlet to an inlet (6i) of a housing (6) that is in fluid communication with a cavity defining the shape of the metal part. The mold / shroud coupling mechanism (14) is configured to receive the short shroud (9) and maintain the short shroud (9) in a shroud-casting position with the short shaft inserted into the bore (7) a shaft-free distance (d710>0) from the housing inlet (6i), where k=d710 / d7 is preferably between 0.2 and 0.8.

Description

[Technical Field]

[0001] The present invention refers to a mold assembly including a sand casting mold, a short shroud, and a mold / shroud coupling mechanism for coupling the short shroud to the sand casting mold at a shroud casting location. The use of a short shroud rather than the known long shroud significantly reduces the cost of casting metal in a shrouded metal stream in foundry applications by saving a significant amount of expensive refractory material forming the shroud. [Background technology]

[0002] In foundries, metal parts are produced by pouring metal from a ladle nozzle into a bore that leads to a sand casting mold cavity that defines the geometry of the part being cast. One of the main challenges in such metal casting processes is avoiding air entrapment as the metal is poured into the bore. This causes defects, including air bubbles and oxide films, which can cause cracks in the casting.

[0003] It is known in the art to protect the molten steel from air entrapment and bifilm formation during the casting process by using a shroud extending along the entire length of the bore to avoid air entrapment. A sealing gasket can be applied to the shroud inlet to prevent air from being drawn into the metal stream at the contact interface between the ladle nozzle and the shroud. This gasket also has the advantage of protecting the nozzle and shroud from mechanical damage upon contact, due to the brittleness of ceramic materials. The shroud outlet is introduced into a housing, sometimes equipped with a filter unit to prevent solid particles from entering the mold cavity. A mold / shroud coupling mechanism is used to ensure reproducible and stable positioning of the shroud within the bore of the sand casting mold.

[0004] A system for casting molten metal is disclosed in EP 3463715. This system comprises: a sand casting mold comprising an inlet and a casting cavity having a bore extending between a top surface of the mold and the inlet; A shroud comprising a shroud base and a hollow shaft, the shroud base being located outside the mold adjacent the top surface, the hollow shaft being housed in a bore and movable therein.

[0005] To achieve a sealed contact between the nozzle and the shroud base, EP3463715(B1) proposes a mold / shroud coupling mechanism that includes a lift mechanism located on the upper surface of the mold. The lift mechanism includes a concentrically arranged first collar and a second collar. The first collar is fixed to the upper surface of the mold, and the second collar is rotatably coupled to the upper surface of the mold and supports the shroud base. A bayonet system, including a follower engaged in an inclined slot, allows the second collar to be lifted relative to the upper surface of the mold by rotation, thus causing linear movement of the shroud. Rotation of the bayonet system is performed by an operator. Once the shroud base contacts the nozzle, the lift mechanism no longer moves during the entire casting operation, ensuring a stable and reproducible process. However, the lack of freedom of movement of the shroud during casting can be problematic because the flow of molten metal through the shroud causes vibrations that propagate to the contact area between the nozzle and the shroud base, which can cause wear or even cracks in the refractory material. Furthermore, securing the bayonet requires human operator intervention, thus increasing costs and safety risks when operating above the workshop floor level.

[0006] To solve this problem, an alternative mold / shroud coupling mechanism is proposed in PCT / EP2022 / 072007, in which the first and second collars are coupled by a spring, so that upon application of a vertical load to the shroud seated on the first collar, the shroud is driven downwardly within the bore, forming a dynamic seal between the nozzle and the shroud inlet, and between the shroud outlet and the filter housing.

[0007] Casting metal parts in foundry applications using a shroud as described above is highly advantageous in that air entrapment in the shrouded metal stream is significantly reduced. However, this solution increases the cost of the process because the shroud is made of a refractory material that is more expensive than any material used in sand casting molds.

[0008] The present invention proposes a solution for producing metal parts in foundries, which brings together the advantages of the shrouded casting assemblies discussed above, at a much lower cost. This and other advantages of the present invention will be explained in more detail subsequently. Summary of the Invention

[0009] The accompanying independent claims define the invention. The dependent claims define preferred embodiments. In particular, the invention relates to a kit of parts for casting molten metal comprising a short shroud, a sand casting mold, and a mold / shroud coupling mechanism.

[0010] The short shroud a shroud base attached to the proximal end of a short shaft having a shaft length (d10) measured along the Z axis; and a shroud bore extending along the Z-axis from a shroud inlet opening in the shroud base to a shroud outlet opening at the downstream end of the short shaft; Sand casting molds are ● a casting cavity having a cavity entrance; a housing selected from a filter housing and a diverter housing, the housing having a housing outlet in fluid communication with the cavity inlet and a housing inlet in fluid communication with the bore; a bore extending over a bore length (d7) along the Z axis between a bore inlet opening at the top surface of the sand casting mold and a bore outlet opening at its downstream end at the level of the housing inlet, the downstream end being provided with a bore choke; the bore choke reduces the bore diameter by at least 10% in the flow direction along the Z-axis to form a bore constriction defining a bore outlet that opens into the housing; The mold / shroud coupling mechanism is • A seat member configured to receive the shroud base and hold the short shroud in a shroud casting position where the downstream end of the short shaft (10) is inserted into the bore.

[0011] The shaft length (d10) is shorter than the bore length (d7) (i.e., d10 < d7). As a result, at the shroud casting position, the downstream end of the short shaft is separated from the housing inlet by a distance (d710) without a shaft that is proportional to the bore length (d7) by a proportionality coefficient (k) (i.e., d710 = kd7). The proportionality coefficient (k) is preferably at least 20% (i.e., k ≥ 0.2), more preferably at least 35% (i.e., k ≥ 0.35), and the proportionality coefficient (k) is preferably 90% or less (i.e., k ≤ 0.9), more preferably 80% or less (i.e., k ≤ 0.8), more preferably more than 70% (i.e., k ≤ 0.7), and most preferably 60% or less (i.e., k ≤ 0.6). In terms of absolute value, the penetration depth of the short shaft (10) in the bore (7) at the shroud casting position (= d7 - d710) is preferably equal to at least 3 cm (i.e., d7 - d710 ≥ 3 cm), more preferably equal to at least 5 cm (i.e., d7 - d710 ≥ 5 cm), and most preferably equal to at least 10 cm (i.e., d7 - d710 ≥ 10 cm). When 5 cm ≤ d7 - d710 ≤ 3 cm, it is preferable to provide a sealing material (e.g., gasket) between the bore (7) and the short shaft (10) to ensure the airtightness of the gap formed between the two.

[0012] In a preferred embodiment, the mold / shroud coupling mechanism ● A base member fixed to the upper surface, ● A sheet member configured to receive the shroud base and hold the short shroud (9) in the shroud casting position.

[0013] The base member and the seat member each include a central hole aligned with one another for introduction toward the bore for the shroud. The seat member is coupled to the base member by at least one flexible element such that the seat member is movable relative to the base member from a seat rest position to a seat casting position upon application of a load to the seat member parallel to the Z axis that deforms the at least one flexible element so as to separate the seat member from the base member and drive the short shroud seated on the seat member to reach the shroud casting position.

[0014] The flexible element preferably comprises: a spring, preferably a spiral spring, or one or more elastic elements comprising an elastomeric material at the process temperature, extending between the seat member and the base member; or • A free-flowing material enclosed within one or more bags configured to deform upon application of a load to the sheet member.

[0015] The mold / shroud coupling mechanism preferably includes at least three resilient elements, preferably at least three spiral springs, extending between the seat member and the base member, the at least three resilient elements preferably being equally spaced around the circumference of the central bore of the seat member and the base member.

[0016] To strengthen the walls of the bore, the bore is preferably lined with a lining over at least a portion of the bore length (d7), preferably over the entire bore length (d7). The lining material may be selected from chamotte (or grog), preferably composed of highly calcined clay, a sand core material, or a cellulose material.

[0017] The present invention also relates to a sand casting mold assembly comprising a short shroud and a sand casting mold as defined above, wherein a shroud base of the short shroud is seated on a seat member with a short shaft of the short shroud inserted into a bore with its downstream end away from the housing inlet.

[0018] In a preferred embodiment, the mold / shroud coupling mechanism includes a flexible element as discussed above. In this embodiment, the mold / shroud coupling mechanism includes: In the seat rest position, the downstream end of the short shaft is maintained at a distance from the housing inlet that is greater than the distance without the shaft (d710), and ●In the seat casting position, when a load parallel to the Z axis is applied, the downstream end of the short shaft is configured to maintain the short shroud in the shroud casting position with the shaft at a distance from the housing inlet substantially equal to the shaft-free distance (d710).

[0019] The present invention also provides Short shroud and sand casting moulds as defined above, a casting apparatus comprising a ladle with a nozzle provided at the base of the ladle for dispensing molten metal from the ladle, The nozzle is configured to reversibly and sealingly engage the shroud inlet of the short shroud. The ladle is adapted to be inserted into the sand casting mold, e.g., to position the nozzle over the mold / shroud coupling mechanism in substantial alignment along the Z axis; and The nozzle is configured to be displaced downward along the Z axis until the downstream end of the short shaft is outside the housing inlet and engages the shroud inlet of the short shroud at the shroud casting position a shaft-free distance (d710) from the housing inlet.

[0020] In a preferred embodiment, the casting apparatus includes a ladle / shroud coupling mechanism configured to reversibly grip the short shroud to the nozzle, preferably without forming a seal between the shroud inlet and the nozzle. a base adapter fixed to the shroud base of the short shroud, the base adapter comprising a retaining means; a nozzle adaptor adapted to be fixed relative to the ladle base or nozzle and adapted to engage with the retaining means of the base adaptor to reversibly lock the short shroud (9) on the nozzle in a locked position.

[0021] For example, the retaining means of the base adaptor may comprise a retaining peg and the nozzle adaptor may comprise: a fastening hook configured to reversibly engage with the retention peg, preferably configured to self-engage with the retention peg; or • A bayonet coupling element configured to interact with one or more retention pegs to reversibly lock the shroud to the nozzle in a locked position.

[0022] In a preferred embodiment, the mold / shroud coupling mechanism includes a flexible element as discussed above. In this embodiment, the downstream end of the short shaft reaches a casting position a shaft-free distance (d710) from the housing inlet by applying a load parallel to the Z axis to the sheet member.

[0023] The present invention also relates to a method for casting molten metal using a casting device according to any one of claims 8 to 11, comprising the following steps: lowering the ladle along the Z axis until the nozzle is engaged in sealing contact within the shroud inlet and the short shroud is in a shroud casting position with its downstream end outside the housing inlet and a shaft-free distance (d710) from the housing inlet, with the shroud base seated on the seat member; • The process of allowing molten metal to flow from the ladle into the casting cavity through a nozzle, a short shroud, and a housing.

[0024] In a preferred embodiment, the mold / shroud coupling mechanism includes a flexible element as discussed above. In this embodiment, the ladle is lowered along the Z axis until the nozzle (engaging the shroud inlet) applies a load parallel to the Z axis to the shroud base seated on the seat member, thus moving the seat member along the Z axis relative to the base member against the flexible element and forming a sealed contact between the nozzle and the shroud inlet of the short shroud in the shroud casting position, with its downstream end outside the housing inlet and spaced a shaft-free distance (d710) from the housing inlet.

[0025] In this embodiment, the short shroud is first placed into the sand casting mold with the seat member receiving the shroud base and holding the short shroud with its downstream end outside the housing inlet and a distance greater than the shaft-free distance (d710) from the housing inlet to form a sand casting mold assembly as described above. The nozzle is then engaged with the shroud inlet by vertically lowering the ladle, and further lowering the ladle for the nozzle to apply a load to the shroud base, forming a sealing contact between the nozzle and the short shroud, moving the short shroud toward the housing inlet to a shroud casting position with its downstream end the shaft-free distance (d710) from the housing inlet.

[0026] Alternatively, the nozzle may be engaged with a shroud inlet of a short shroud, the short shroud having A retaining means for the base adapter fixed to the shroud inlet of the short shroud is provided. Engage with a nozzle adapter fixed to the base or nozzle of the ladle, For example, by locking the short shroud (9) to the nozzle (12) in a locked position, it is held to the nozzle using a ladle / shroud coupling mechanism.

[0027] The short shroud, locked to the nozzle, can be positioned in substantial alignment along the Z-axis on the mold / shroud coupling mechanism and lowered along the Z-axis until the shroud base is seated on the seat member with the short shroud within the bore and its downstream end a distance greater than the shaft-free distance (d710) from the housing inlet. At this point, the ladle can be further lowered along the Z-axis until the short shroud reaches a shroud casting position with its downstream end (10d) outside the housing inlet and the shaft-free distance (d710) from the housing inlet, thereby forming a sealed contact between the short nozzle and the short shroud. Casting of metal can begin.

[0028] The invention will now be described in more detail with reference to the following drawings. [Brief explanation of the drawings]

[0029] [Figure 1] 1 illustrates steps in a metal casting method using a casting apparatus according to an embodiment of the present invention. [Figure 2] 1 illustrates steps in a metal casting method using a casting apparatus according to an alternative embodiment of the present invention, including a ladle / shroud coupling mechanism (140). [Figure 3] 1 shows a perspective view of one embodiment of a mold / shroud coupling mechanism suitable for the present invention. [Figure 4] 4 shows a cross section of the mold / shroud coupling arrangement and the short shroud housed therein along line IV-IV of FIG. 3. [Figure 5] 1 shows a perspective view of a casting apparatus according to the present invention, with the ladle nozzle positioned vertically above a short shroud in a shroud casting position and the shroud base received in a seat member of a mold / shroud coupling mechanism, the ladle not being shown for clarity. [Figure 6] 6 shows a cross-sectional view of the casting apparatus of FIG. 5 with the nozzle reversibly and sealingly engaged with the shroud base despite slight misalignment of the nozzle coaxially with the bore axis. [Figure 7a]1 shows a cross-sectional view of the mold / shroud coupling mechanism and nozzle in a casting apparatus according to the present invention as the ladle moves over the mold and aligns the nozzle with the shroud inlet. [Figure 7b] 1 shows a cross-sectional view of the mold / shroud coupling mechanism and nozzle in a casting apparatus according to the present invention as the ladle is lowered to bring the nozzle close to or into contact with the shroud inlet. [Figure 7c] 10 shows a cross-sectional view of the mold / shroud coupling mechanism and nozzle in a casting apparatus according to the present invention as the ladle is further lowered to compress the flexible element and form a sealing contact. [Figure 8] 10A shows a perspective bottom view of a sheet member of a mold / shroud coupling mechanism according to one embodiment of the present invention. FIG. [Figure 9a] FIG. 10 shows a cross-sectional view of a ladle / shroud coupling mechanism in a casting apparatus according to one embodiment of the present invention prior to clamping of the short shroud to the nozzle. [Figure 9b] 9a shows a cross-sectional view of the ladle / shroud coupling mechanism in the casting apparatus of FIG. 9a, in which the short shroud is unsealedly coupled to the nozzle and holds the short shroud vertically above the mold / shroud coupling mechanism. [Figure 9c] 9a shows a cross-sectional view of the ladle / shroud and mold / shroud coupling mechanism in the casting apparatus of FIG. 9a, where the base adapter is received in the seat member of the mold / shroud coupling mechanism that holds the short shroud, and the flexible element is in a stationary state. [Figure 9d] 9a shows a cross-sectional view of the ladle / shroud and mold / shroud coupling mechanism in the casting apparatus in FIG. 9a, where the ladle is further lowered vertically with the short shroud gripped by the nozzle until the nozzle applies a load to the flexible member, thus forming a sealing contact between the nozzle and the short shroud. [Figure 10] 9b shows a view of the ladle / shroud coupling mechanism in the casting apparatus of FIG. 9a prior to clamping the short shroud to the nozzle in the shroud casting position. [Figure 11]11 shows a diagram of the ladle / shroud coupling mechanism in the casting apparatus of FIG. 10 with the short shroud gripped to the nozzle in the shroud casting position. [Figure 12] 11 shows a detailed cross-sectional view of the ladle / shroud coupling mechanism of FIG. 10. [Figure 13] 12 shows a detailed cross-sectional view of the ladle / shroud coupling mechanism of FIG. 11. [Figure 14] FIG. 1 shows a detailed view of the ladle / shroud coupling mechanism in a casting apparatus according to the present invention, in which a short shroud is coupled to the nozzle and vertically translates (up or down) the ladle and its coupled short shroud above the mold. [Figure 15] 1 shows a detailed cross-sectional view of a casting apparatus with a ladle / shroud coupling arrangement according to the present invention in a shrouded casting position with a short shroud gripped by the nozzle. [Figure 16a] 1 shows an embodiment of a flexible element according to the present invention. [Figure 16b] 1 shows an embodiment of a flexible element according to the present invention. [Figure 16c] 1 shows an embodiment of a flexible element according to the present invention. [Figure 16d] 1 shows an embodiment of a flexible element according to the present invention. [Figure 16e] 1 shows an embodiment of a flexible element according to the present invention. [Figure 16f] 1 shows an embodiment of a flexible element according to the present invention. [Figure 17a] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17b] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17c] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17d] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17e] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17f] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17g] 1 illustrates an embodiment of a kit of parts of the present invention. [Figure 17h]1 illustrates an embodiment of a kit of parts of the present invention. [Figure 18a] 1 shows an example of a long shroud of the prior art having a long shaft with a long shaft length d10L. [Figure 18b] 1 shows an example of a short shroud of the present invention having a short shaft with a shaft length d10. [Figure 18c] 18a and 18b show top views of the long and short shrouds. [Figure 18d] 18a and 18b graphically illustrate material weight savings as a function of shaft length (d10) for the shroud illustrated in FIGS. 18a and 18b, expressed in terms of a proportionality factor k, defined as k=d10 / d10L, k=0 (i.e., d10=0) to 100% (i.e., d10=d10L). DETAILED DESCRIPTION OF THE INVENTION

[0030] In a first aspect, the present invention relates to a kit of parts for casting molten metal, comprising a short shroud (9), a sand casting mold (2), and a mold / shroud coupling arrangement, for example as illustrated in Figures 17(a) to 17(c).

[0031] For example, as illustrated in Figures 4, 9a, and 17a-17h, the short shroud (9) comprises a shroud base (11) attached to the proximal end of a short shaft (10) having a shaft length (d10) measured along the Z-axis. The short shroud has a shroud bore extending along the Z-axis from a shroud inlet (9i) opening in the shroud base (11) to a shroud outlet (9o) opening at the downstream end (10d) of the short shaft. The short shaft (9) suitable for the present invention differs from prior art shrouds in that the short shaft (10) has a substantially shorter shaft length (d10) as prior art shrouds, as discussed in detail below.

[0032] For example, as shown in Figures 5, 6, and 17a to 17h, the sand casting mold (2) is a bore (7) in fluid communication with the cavity (3); a housing (6) having a housing inlet (6i) and a housing outlet (6o); - One or more casting cavities (3).

[0033] The bore (7) extends a bore length (d7) along the Z axis between a bore inlet opening in the top surface (8) of the sand casting mold and a bore outlet opening at the downstream end, the downstream end comprising a bore choke (7c) forming a bore constriction defining a bore outlet that opens into the housing (6) with a bore diameter reduction of at least 10% along the Z axis in the flow direction.

[0034] The housing (6) is selected from among a filter housing and a diverter housing. In both cases, the housing includes a single housing inlet (6i) in fluid communication with the bore outlet and one or more housing outlets (6o) in fluid communication with one or more cavities (3). The housing is configured to distribute the flow of molten metal across the housing from the housing inlet (6i) to one or more housing outlets (6o) connected to the casting cavities. The housing (6) can be a filter housing including a filter element for filtering and removing solid impurities in the flow of molten metal.

[0035] The one or more casting cavities (3) have a geometry that defines the geometry of the part to be cast. Each of the one or more casting cavities (3) has a cavity inlet (4) that is in fluid communication with the housing outlet (6o). Figures 5 and 6 show a mold (2) with a single cavity (3), while Figures 15 and 17a-17h show molds with several cavities (3).

[0036] During use, molten metal flows through the bore inlet, enters the housing, and fills one or more cavities (3). If the molten metal is cast directly into the bore (7) without any specific protection from exposure to the atmosphere, oxide inclusions form and become entrapped in the flowing melt, forming defects in the cast metal. This problem has been largely solved by using a shroud that extends from the bore inlet down the bore length (d7) through the housing inlet (6i) into the housing (6), thus forming a continuous, substantially airtight flow path extending from the ladle to the cavities (3). This is described, for example, in EP 3463715 and PCT / EP2022 / 072007, discussed above, and such a shroud is commercially available from Foseco under the trademark Hollotex®. The shroud must be seated on a mold / shroud coupling mechanism to ensure that the shroud is repeatedly and stably maintained in its casting position. The kit of parts of the present invention also includes a shroud, i.e., a short shroud, and therefore must also include a mold / shroud mating mechanism (14) for receiving and maintaining the short shroud (9) in the shroud casting position.

[0037] The mold / shroud coupling mechanism (14) suitable for the present invention comprises a seat member (15) configured to receive the shroud base (11) and hold the short shroud (9) in the shroud casting position where the downstream end (10d) of the short shaft (10) is inserted into the bore.

[0038] The gist of the present invention is that the short shaft (10) has a shaft length (d10) shorter than the bore length (d7), that is, d10 < d7. Thus, contrary to the prior art shroud system discussed above, at the shroud casting position, the downstream end (10d) of the short shaft is separated from the housing inlet (6i) by a shaftless distance (d710) greater than zero. The shaftless distance (d710) can be defined to be proportional to the bore length (d7) by a proportionality coefficient (k < 1). For example, the proportionality coefficient (k) can be at least 30%, preferably at least 40%, more preferably at least 50% (i.e., d710 = kd7, preferably k ≥ 0.3, preferably k ≥ 0.4, more preferably k ≥ 0.5).

[0039] To ensure a close interface between the short shaft (10) and the bore wall, the short shaft (10) must penetrate into the bore (7) over at least a certain distance. For example, the proportionality coefficient (k) can be 90% or less (i.e., k ≤ 0.9), preferably 80% or less (i.e., k ≤ 0.8), more preferably more than 70% (i.e., k ≤ 0.7), most preferably 60% or less (i.e., k ≤ 0.6). When the ratio coefficient (k) is less than 1, the short shaft (10) needs to have a length (d10) such that it does not penetrate the bore (7) over the entire bore length (d7). The penetration depth of the short shaft (10) in the bore (7) at the shroud casting position can be defined as equal to (d7 - d710). The penetration depth is preferably equal to at least 3 cm (i.e., d7 - d710 ≥ 3 cm), more preferably equal to at least 5 cm (i.e., d7 - d710 ≥ 5 cm), most preferably equal to at least 10 cm (i.e., d7 - d710 ≥ 10 cm).

[0040] A shroud having a short shaft (10) with a shaft length (d10) as shown in FIG. 18b, which is smaller than the shaft length (d10L) of a prior art shroud as shown in FIG. 18a (which must be greater than d7), is advantageous in that significantly less refractory material is required to manufacture the short shroud than a state-of-the-art shroud. The cost of the most expensive consumable item in the shrouded metal casting foundry process is proportionally reduced. The weight of the short shroud is also proportionally reduced, thereby making it easier to handle. Another advantage of the short shroud (9) is illustrated in FIG. 2, where station (1a) has a short shroud (9) coupled to a nozzle (12) below a ladle (103) that moves around the work area. Moving a ladle with a short shroud (9) coupled to it is substantially easier than with a long shroud, as in the prior art (see, e.g., PCT / EP2022 / 072007).

[0041] Short Shroud(9) As shown in Figure 15, during casting, molten metal contained in the ladle (103) is distributed through a nozzle (12) located in the lower portion of the ladle (103), from which it flows into the cavity (3) via the short shroud (9), the unshrouded distance (d710) of the bore (7), the housing (6), and the feed channel (5). The short shroud (9) comprises a shroud base (11) attached to the proximal end of a shaft (10), which is hollow and has a shroud bore opening at a shroud inlet (9i) in the shroud base and extending to a shroud outlet (9o) opening at the distal end (10d) of the hollow shaft.

[0042] The gist of the present invention is to replace the long shroud (9L) extending along the entire bore length (d7) from the bore inlet to the housing inlet (6i) described in the prior art (e.g., EP 3 463 715 and PCT / EP2022 / 072007) by a short shroud (9) whose shroud outlet (9o) is a shaft-free distance (d710) from the housing inlet (6i). This reduction in shaft length (d10) results in a corresponding saving of expensive material and therefore a cost reduction, while maintaining the advantages described in the aforementioned documents.

[0043] The shroud base 11 of the short shroud 9 of the present invention is identical to the shroud base of the long-shaft shroud described in the cited prior art. Accordingly, the shroud inlet 9i is shaped to receive the nozzle 12 and form a sealed interface with the nozzle. As with the prior art long shrouds, the nozzle 12 of the ladle 103 must sealingly engage with the shroud inlet 9i to prevent air from being drawn into the molten metal flow through the interface between the nozzle and the shroud inlet 9i, while simultaneously preventing molten metal from leaking therethrough. The sealing contact between the nozzle 12 and the shroud inlet 9i is achieved by the complementary mating geometries of the nozzle tip and the shroud inlet. The shroud inlet can have either a curved or frusto-conical cup geometry, and the nozzle tip can have a corresponding protruding mating geometry. Pressure can be applied to the interface via the ladle's (103) Z-axis movement, which drives the nozzle tip into the mating shroud inlet (9i). If necessary, a sealing joint or gasket can be applied to ensure enhanced sealing of the interface. A static or dynamic seal can be formed between the moving nozzle (12) and the shroud inlet (9i). A dynamic seal can include, for example, an expandable sealing material, such as a gasket, packed into the shroud inlet, as described for sliding gates in WO 2013 / 088249 A2. As shown in Figures 17e-17h, the shroud bore of the short shroud (9) can include a lining insert (9L). Such a lining insert (9L) is advantageously made from a consumable material selected for its durability under the specific conditions of a single sand casting operation and its effectiveness in keeping the shroud bore largely free of molten metal residue. This consumable material can be, for example, a composition of cellulose, selected grades of minerals, and a binder. Alternatively, the insert may be made of a refractory material. The thickness of this lining insert (9L) generally ranges from 3mm to 10mm.This is in contrast to the wall thickness of the short shroud (9) itself, which is typically 15 mm to 20 mm. With this configuration, the short shroud (9) can be efficiently reused over multiple sand casting operations. This is enabled by simply replacing the lining insert (9L) after each operation, allowing a single short shroud (9) to be repeatedly used. Additionally, the lining insert (9L) preferably includes an integral gasket (9g) designed to seamlessly contact the nozzle (12) of the ladle (103). However, the integration of the gasket (9g) may not be necessary if the lining insert (9L) inherently has the mechanical properties necessary to accommodate the nozzle (12). This is particularly true when the insert includes a material such as cellulose. Additionally, a metal can (not shown in the figures) can be lined on its outer surface to enhance the resistance of the short shroud (9) to molten metal leakage and thermal shock. The lining insert (9L) provides a highly versatile mounting option. The lining insert can be pre-assembled onto the short shroud (9) prior to its integration into the sand casting mold assembly, as demonstrated in FIGS. 17e and 17f. Alternatively, the insert (9L) can be mounted onto the short shroud (9) following the installation of the short shroud into the sand casting mold assembly, which is the process illustrated in FIGS. 17g and 17h.

[0044] The short shroud (9) of the present invention differs from the long shroud (9L) of the cited prior art in that the long shaft of the long shaft length, the latter d10L>d7, has been replaced by a short shaft (10) with a shaft length d10<d7<d10L. The shaft lengths of both the long shroud and the short shroud are defined as the portion of the shroud with a shroud outlet (9o) whose bore has a substantially constant hydraulic diameter (Dh10), where the hydraulic diameter is defined as the ratio 4A / P, A is the cross-sectional area, and P is the outer perimeter of the bore. For a circular cross-section, the hydraulic diameter (Dh) is equal to the diameter of the bore.

[0045] Figures 18a and 18c show an example of a long shroud from the cited prior art, with a simplified geometry including a shroud base (11) with a cylindrical section of diameter (Dhi) followed by a frusto-conical shroud inlet (9i) with a smaller diameter (Dh10) attached to a long cylindrical shaft (10) of length (d10L) with a constant bore diameter (Dh10). This simplified geometry is a reasonable representation of the actual shroud geometry and is sufficient for purposes of illustrating the material savings when shortening the shaft length (d10). The wall thickness (tw) is constant. Figure 18b shows a corresponding short shroud (9) according to the present invention, with an identical shroud base (11) and a short shaft of the same diameter but shorter shroud length (d10), where d10 = a × d10L. Examples of different dimension values ​​for the long shroud (9L) are listed in Table 1, and the corresponding calculated weight (m9L) is ρ = 2.4 g / cm 3 Considering the density of the refractory material, if the shaft length is 100 cm, the weight of the long shroud (9 L) in Figure 18a is about 11 kg. [Table 1]

[0046] Figure 18b shows the corresponding short shroud (9) according to the present invention. Since the short shroud (9) only has a shorter shaft length d10 < d10L which is different from the long shroud of Figure 9a, the top view of the shroud in Figure 9c is the same for both the long and short shrouds of Figures 9a and 9b. The shaft length (d10) of the short shaft (10) according to the present invention is shorter than the long shaft length (d10L) of the long shroud. The shroud length (d10) can be expressed as d10 = a × d10L < d10L, where it is proportional to the long shaft length (d10L) by a proportionality factor (a), a < 1, and a is preferably 0.2 to 0.8 (as shown in Figure 18a), more preferably 0.35 to 0.6. Figure 18d graphically illustrates the relative weight reduction ((m9L - m9) / m9L) between the weight (m9) of the short shroud (9) and the weight (m9L) of the long shroud (9L) as a function of the proportionality coefficient a = d10 / d10L. The lightly shaded region identifies the preferred range of 0.2 < a < 0.8 (i.e., d10 = 20 to 80 cm), which results in a weight reduction of 75 to 20% respectively. Thus, the weight of the short shroud (9) is 2 to 7.9 kg instead of 11 kg. The darkly shaded region identifies the more preferred range, 0.35 < a < 0.6 (i.e., d10 = 40 to 60 cm), which results in a weight reduction of 60 to 40% respectively. Thus, the weight of the short shroud (9) is 3.9 to 6.4 kg instead of 11 kg. This has the advantage of reducing the cost of the non-essential shroud and also greatly facilitates the handling of the shroud by the operator.

[0047] The short shroud (9) is made of a refractory material, such as fused silica, alumina graphite, or other materials known in the art. The outer wall of the shroud base (11) can have a conical shape with a sloped shoulder (23) that rests on a seat element (15). In one embodiment, the shoulder rests on a filler (22) that fills the space between the sleeve of the seat element (15) and the shroud base, as shown in Figure 4. Alternatively, the shroud shoulder rests directly on the seat element, as shown in Figures 9c, 9d, 12, and 13.

[0048] The main purpose of the long shaft of the long shroud (9L) in the cited prior art is to span the distance separating the tip of the nozzle (12) from the housing inlet (6i) and prevent the flowing metal melt from contacting the air between the ladle (103) and the cavity (3) of the mold (2). Protecting the molten metal from contact with air can also be achieved with a short shroud (9), whose short shaft does not reach the housing inlet (6i) but is separated therefrom by a shaft-free distance (d710) by ensuring sealed contact between the short shaft (10) and the bore (7).

[0049] A simple approach to creating a seal between the short shaft 10 and the bore 7 is to dimension the short shroud 9 so that, when the short shaft 10 is in the shroud casting position, only a narrow gap remains between the short shaft 10 and the wall of the bore 7. When the bore 7 is filled with molten metal as it flows through the nozzle 12 and the short shroud 10, some metal flows into the gap between the short shaft 10 and the cold wall of the bore 7 and freezes to form a solid layer that seals the bore 7 from the atmosphere. To enhance the seal, a sealing gasket or sealing material can be provided to seal the gap from the atmosphere. Again, in addition to sealing materials known in the art, an expanding material can be used to create a dynamic seal, as described in WO 2013 / 088249, particularly when the mold / shroud coupling mechanism 14 includes flexible or elastic elements.

[0050] The shroud outlet (9o) may include one or more apertures for distributing molten metal within the bore (7).

[0051] Mold / shroud coupling mechanism (14) To receive and maintain the short shroud (9) in the shroud-casting position for the duration of the casting operation, the mold according to the present invention is provided with a mold / shroud coupling mechanism (14). The type of mold / shroud coupling mechanism is not critical to the present invention, so long as it performs the dual function of receiving the short shroud (9) and maintaining it in the shroud-coupling position for the entire duration of the casting operation. However, the following types of mold / shroud coupling mechanisms (14) are preferred: (1) flexible element, and (2) lift coupling.

[0052] Mold / shroud coupling mechanism (14) - with flexible element A preferred type of mold / shroud coupling mechanism (14) includes a flexible element (17), as shown in Figures 3 and 4. As shown in Figure 6, the mold / shroud coupling mechanism (14) is configured to accommodate the shroud (9) of the casting apparatus (1) in a defined shroud casting position, where the short shaft (10) is accommodated in the bore (7), with its distal end (10d) spaced a shaft-free distance (d710) from the housing inlet (6i). During a casting operation, molten metal flows from the ladle through a nozzle (12) sealingly engaged with the shroud inlet (9i) in the shroud casting position. The molten metal then flows along the bore (7) through the short shaft (10) before entering the housing (6) through the bore outlet at the bore choke (7c), exiting the housing through the housing outlet (6o) into a feed channel, and filling the casting cavity (3).

[0053] Base member (16) and seat member (15) As shown in FIGS. 3 and 4, the mold / shroud coupling mechanism (14) includes a base member (16) fixed to the upper surface (8) of the mold (2), and a sheet member (15) configured to receive the shroud base (11) and hold the short shroud (9) in the shroud casting position. As shown in FIGS. 3 and 4, the sheet member (15) is coupled to the base member (16) by at least one flexible element (17), such that the sheet member (15) is spaced apart from the base member (16) when the mold / shroud coupling mechanism (14) is in a stationary state, and is movable relative to the base member (16), preferably towards the base member (16), upon application of a load along the Z-axis to the sheet member (15) that deforms at least one flexible element (17) and reduces the stationary distance (h0) to the casting distance (h1) at which the sheet member (15) is spaced apart from the base member (16). The flexible element (17) will be described in more detail subsequently and is defined as an element that significantly deforms along the Z-axis when a load is applied along the Z-axis.

[0054] The flexible element (17) is configured to deform upon application of a vertically (i.e., along the Z-axis) and downwardly oriented load by the nozzle (12) of the ladle (103) onto the shroud base (11) received in the sheet member (15), driving both the sheet member (15) and the short shroud (9) from the stationary distance (h0) from the bore inlet to the casting distance (h1 < h0), such that the short shroud (9) reaches the shroud casting position with the shroud outlet (9o) spaced from the housing inlet (6i) by a shaftless distance (d710). Upon release of the load along the Z-axis from the short shroud (9) and the sheet member (15), if the flexible element (17) is an elastic element, the sheet member can return to its stationary distance (h0) from the bore inlet, if the flexible element (17) is a plastic element, it can remain at the casting distance (h1), or if the flexible element (17) is a viscoelastic element, it can return with a delay to either the stationary distance (h0), or to some point between the casting distance (h1) and the stationary distance (h0).

[0055] In a preferred embodiment of the mold / shroud coupling mechanism (14) with the flexible element (17), it is not necessary to manually adjust the position of the short shroud (9) received on the seat member (15) relative to the nozzle (12) to engage the shroud inlet (9i) with the nozzle (12) of the ladle (103). In one embodiment of the present invention, the short shroud is coupled to the mold at a rest distance (h0) from the bore inlet, i.e., with the shroud base resting on the seat member (15) of the mold / shroud coupling mechanism (14), the short shaft (10) is housed in the bore (7), and the shroud outlet (9o) is spaced from the housing inlet (6i) by a distance greater than d710 (the shroud outlet (9o) is actually spaced from the housing inlet (6i) by a distance [d710+(h0-h1)]). In a stationary state, the shroud base (11) rests on the seat member (15) at a stationary distance (h0) from the base member (16) maintained by the reaction force of the flexible element (17) biased in that manner. The nozzle (12) of the ladle (103) is lowered into engagement with the shroud inlet (9i) simply by first moving the ladle along the Z axis to align with and above the shroud inlet (9i), and then lowering the ladle (103) along the Z axis until the nozzle engages the shroud inlet (9i), as illustrated in Figures 7a and 7b. In Figure 7a, the nozzle is aligned with the shroud inlet (9i) along the Z axis and is located a fixed distance from the shroud inlet (9i). The ladle is then lowered, i.e., moved downward along the Z axis toward the shroud base (11), so that the nozzle engages the shroud inlet (9i) of the shroud, as illustrated in Figure 7b. At this stage, the nozzle and shroud inlet (9i) are not mated to form a sealing contact.In order to sealingly engage the nozzle with the shroud inlet (9i) and prevent air and molten metal from leaking through the gap between the nozzle and the shroud inlet (9i), the ladle is then further lowered as illustrated in Figure 7c, so that the nozzle contacts the shroud base (11) which rests on the seat member (15) of the mold / shroud coupling mechanism (14), applying a load along the Z axis and deforming the flexible element (17), thereby moving the seat member (15) towards the base member (16) from the rest distance (h0) to the casting distance (h1), so that, on the other hand, A sealing contact can be formed between the nozzle and the shroud inlet (9i), while • The short shroud (9) reaches the shroud casting position with the shroud outlet (9o) a shaft-free distance (d710) from the housing inlet (6i).

[0056] As shown in FIG. 7c, the movement of the seat member (15) relative to the base member (16), driven by the downward translation of the ladle and enabled by the deformation of the flexible element (17), reduces the distance between the seat member (15) and the base member (16) by (h0-h1), moving it from a rest distance (h0) to a casting distance (h1) (h1 <h0)。

[0057] Another advantage of the mold / shroud coupling mechanism (14) with the flexible element (17) is that it absorbs the energy generated by the movement between the nozzle and the short shroud, caused for example by the impact of the lowering of the ladle (103) or by vibrations during the casting operation, thereby reducing the wear caused by friction between the moving elements.

[0058] The mold / shroud coupling mechanism (14) in the mold of the present invention preferably also allows for compensation for lateral and / or tilt misalignment between the nozzle and the shroud inlet (9i), as shown in FIG. 6 . Lateral misalignment can occur when the ladle is lowered to engage the nozzle with the shroud inlet (9i). Without the flexible element (17) in the mold / shroud coupling mechanism (14), as in the previous example, lateral misalignment could prevent the formation of a sealing contact between the nozzle and the shroud inlet (9i) or cause significant material stress to compensate for the misalignment in order to establish a sealing contact. In the present invention, the lateral misalignment is compensated for by the flexible element, thereby reducing material stress and potential defects in the casting equipment.

[0059] As illustrated in Figures 3, 4, and 5, the base member (16) and seat member (15) of the mold / shroud coupling mechanism (14) according to the present invention can each have a central hole aligned with each other and with the bore entrance to define an introduction path for the short shroud (9) toward the bore (7). In Figures 3, 4, and 5, the base member (16) is circular and has a central hole (20) forming an introduction path into the bore (7) through which the short shaft (10) of the short shroud (9) can pass into the bore (7) until the shroud base (11) rests against the seat member (15) in a stationary position, as shown in Figure 4. As discussed below, the short shroud can be introduced into the bore (7) by a human operator, as shown in Figure 1(1a), or by lowering the ladle with the short shroud attached, as shown in Figures 2(1a), 2(1), and 2(2).

[0060] In one embodiment, the short shroud seats on a seating member (15) (see Figures 1(1a) and (1) and Figure 7a) before the ladle is lowered to establish contact between the nozzle and the shroud inlet (9i), which may be formed by a sleeve (21) with arms (18) distributed around the circumference of the sleeve and extending radially outward therefrom, as illustrated in Figures 3 and 4. A centering pin (19) may be used to center the flexible element.

[0061] The sleeve geometry can mate with the geometry of the outer wall of the shroud base (11) to provide a snug fit for the shroud base (11). Alternatively, as shown in Figures 4 and 7a, the shroud base (11) can be snugly received by the seat member (15) by filling the seat gap with a filler (22), preferably made of molding sand, to form a seat on which the shoulder (23) of the shroud base (11) rests when the shroud (9) is in the casting position. The molding sand filler (22) can include an organic binder, such as a furan or alkali-phenol binder. Other binders, such as inorganic binders or clay minerals, can also be used.

[0062] A preferred embodiment of a mold / shroud coupling mechanism (14) having a flexible element (17) is depicted in FIG. 3. It comprises a seat member (15) with a sleeve configured to receive and retain the shroud base (11). The seat member is coupled to a base member (16) by a flexible member (17) in the form of a spiral spring (17s). The seat member (15) has three radially outwardly extending arms (18) uniformly distributed around the circumference of the sleeve at a radial distance relative to the axis of symmetry of the drive-through. Those skilled in the art will appreciate that the seat member may have any other shape, for example, may be disk-shaped, and the number of outwardly extending arms may vary.

[0063] The base member (16) is preferably firmly secured to the upper surface (8) of the mold (2). For example, the base member can be bonded with an adhesive (organic or mineral) or with fastening means such as screws, rivets, etc. Alternatively, the base member (16) can be seated in a mating recess and held in place by gravity and a load parallel to the Z axis applied by the nozzle (12). This latter embodiment has the advantage that the mold / shroud coupling mechanism can be easily removed before destroying the mold (2) to remove the cast metal part. This is sufficient to ensure that the central hole (20) of the base member remains concentric with the bore (7) during the entire casting operation. The base member also includes three radially outwardly extending arms (18) that align with the corresponding arms of the seat member (15). The flexible element (17) is formed by three spiral springs (17s) sandwiched between the arms of the seat member and the arms of the base member.

[0064] Figure 3 shows three spiral springs 17s, which are the preferred flexible elements 17. However, flexible elements 17 can have other configurations, some examples of which are illustrated in Figures 16a-16f and discussed in more detail in the next section.

[0065] When the shroud base (11) of the short shroud (9) is seated on the seat member (15), the flexible element (17) (e.g., a spiral spring (17s)) maintains the seat member (15) at a rest distance (d0) (see Figures 4 and 7b). During the lowering of the ladle (103), the nozzle engages the shroud inlet (9i) and applies a load along the Z axis to the seat member (15), which deforms the flexible element (17) and drives the seat member to a casting distance (h1), driving the short shroud (9) to a shroud casting position where the shroud outlet (9o) is a shaft-free distance (d710) from the housing inlet (6i). At this stage, A sealed contact is formed between the nozzle (12) and the shroud inlet (9i) by the mating geometry of the two elements, by the application of a load between the two, and optionally by a sealing member. A metal melt can be forced through the nozzle and short shroud (9), filling the bore (7) and flowing into the housing (6) and cavity (3). The narrow gap between the short shaft (10) and the bore wall is rapidly filled with metal, which freezes on contact with the cold mold and forms a seal. Optionally, a sealing member (e.g., a gasket) can be used to ensure the narrow gap is sealed.

[0066] Flexible Elements (17) At least one flexible element (17) of the mold / shroud coupling mechanism of the embodiment discussed above allows the short shroud (9) to be dynamically moved to the shroud casting position by its deformation upon application of a load along the Z-axis. The load is applied by lowering the ladle (103) along the Z-axis until the nozzle (12) contacts and exerts a force on the shroud inlet (9i). The flexible element (17) is an element that deforms significantly along the Z-axis when a load is applied along the Z-axis. The flexible element (17) can exhibit elastic, viscoelastic, or purely plastic behavior.

[0067] The elastic elements are flexible elements (17) that can absorb energy when elastically deformed and instantly release that energy upon release of the load. Mold / shroud coupling mechanisms equipped with elastic elements return to their rest state after use, ready to be used again, so they can be used several times with different molds (2) without replacing the elastic elements. Examples of elastic elements include spiral springs (17s), as shown in Figures 3, 4, 16a, and 16b, or blade springs, as shown in Figure 16e.

[0068] Viscoelastic elements are flexible elements (17) with an elastic modulus (E') and a loss modulus (E''). Upon release of the load, viscoelastic elements either do not recover their initial geometric shape or recover with a time delay. Only the latter type of viscoelastic elements can be used several times in different casting operations. Examples of viscoelastic elements include elastomeric materials such as rubber, as illustrated in Figure 16d, or hydraulic or pneumatic dampers, as shown in Figure 16c, which can be modeled with a spring and shock absorber arranged in parallel.

[0069] The plastic elements are flexible elements (17) that cannot even partially recover their original geometric shape upon the release of a load. For example, this is the case for flexible elements such as beams configured to substantially plastically deform upon the application of a load along the Z axis. This can also be the case for a free-flowing material enclosed in one or more bags or flexible containers configured to viscously deform upon the application of a load to the sheet member (15), as illustrated in FIG. 16f. The free-flowing material can be a particulate material such as sand, which can absorb energy by viscously opposing the load applied by the nozzle to the shroud and sheet member (15). Flexible elements can also include disposable elements configured to break or shatter due to plastic deformation upon the application of a load. Upon the release of the load, the plastic elements maintain their deformed configuration. The plastic elements must either be remolded or removed and replaced with new, undeformed plastic elements each time the mold / shroud coupling mechanism (14) is used again.

[0070] Due to the ready availability of spiral springs (17s), their resistance to casting conditions, and the fact that they can be reused several times without any repairs between two consecutive uses, spiral springs (17s) are the preferred flexible elements (17). Resilient elements are also better suited to maintaining a sealing contact between the shroud inlet (9i) and the nozzle (12) during the casting operation when the ladle (103) and nozzle (12) move slightly up and down due to vibrations during casting.

[0071] Preferably, the mold / shroud coupling mechanism (14) comprises at least three elastic elements, preferably at least three spiral springs (17s), extending between the seat member (15) and the base member (16), as illustrated in Figures 3, 4, and 5, the at least three elastic elements preferably being equally spaced around the circumference of the central bore of the seat member (15) and the base member (16). Preferably, at least three spiral springs, preferably evenly distributed, extend between the seat member (15) and the base member (16). This design has the advantage that the flexible elements (17s) are not excessively heated by molten metal flowing through the shroud bore from the shroud inlet (9i) to the hollow shaft of the shroud during the casting process.

[0072] Mold / shroud coupling mechanism with lift mechanism (14) A mold / shroud coupling mechanism (14) comprising a lift coupling system suitable for use in the present invention is described in EP 3463715 and will subsequently be referred to simply as the "lift mechanism." The lift mechanism comprises a seat member (15) in the form of an inner collar concentrically seated within an outer collar forming a base member (16). The inner collar comprises an annular seat configured to receive and support the shroud base (11), with a short shaft passing through the central hole and bore entrance and inserted into the bore (7). Two pegs and handles extend radially from and are distributed across the outer surface of the inner collar.

[0073] The base member (16) formed by the outer collar comprises a cylindrical wall surrounding an annular base. The base 70 is glued, screwed, or simply placed on top of the upper surface of the mold in the same manner as the base members of the mold / shroud coupling mechanism having flexible members discussed above, preferably mounted within a mating recess that prevents any lateral movement (across the plane perpendicular to the Z axis that defines the upper surface of the mold).

[0074] The cylindrical wall of the outer collar is notched to provide at least two inclined or spiral surfaces that rise a distance (h1-h0) from a rest position at h0 to a casting position at h1 from the top surface of the mold. The inner collar is inserted into the outer collar with its peg resting on the inclined surfaces of the outer collar at rest position h0. By rotating the inner collar using a handle, the peg advances along the inclined surfaces, lifting the inner collar, and thus the short shroud 9 supported by the inner collar, upward until it reaches casting position h1. The inner and outer collars thus function as a cylindrical cam, and the peg constitutes the follower.

[0075] Unlike the mold / shroud coupling mechanism with flexible elements discussed above, the lift mechanism drives the short nozzle away from the housing inlet (6i) to reach the shroud casting position. Thus, in the rest position, the shroud outlet (9o) is closer to the housing inlet (6i) than it is at the shroud casting position by a distance d710-(h1-h0), and is spaced from the housing inlet by a shaft-free distance (d710).

[0076] In use, the ladle (103) and nozzle (12) are lowered along the Z axis until they contact or nearly contact the shroud inlet (9i) without forming a sealed contact, which is formed by lifting the shroud inlet (9i) above the nozzle (12) by rotating the inner collar relative to the outer collar, as described above.

[0077] The mold / shroud coupling mechanism with flexible elements discussed above is preferable to the lift mechanism for the following reasons: First, the flexible elements allow for more automation because they provide a dynamic, self-adjusting sealing contact mechanism that requires no human intervention other than lowering the ladle to engage the nozzle with the shroud opening. Second, as will be explained in more detail subsequently, the lift mechanism can be used solely by first inserting the short shroud into the bore (7) and then lowering the ladle, as illustrated in FIG. 1. The mold / shroud coupling mechanism with flexible elements also offers the possibility of coupling the short shroud directly to the nozzle and driving the short shaft (10) into the bore (7) by controlling the displacement of the ladle (103) and nozzle (12).

[0078] Sand Casting Mold(2) The mold (2) is a sand casting mold made of sand compressed with a binder. The mold has a bore (7) extending from a bore inlet to a bore outlet located within a bore choke (7c) and opening into a housing inlet (6i) leading to the housing (6). The sand casting mold (2) has one or more cavities (3) fluidly connected to the housing (6) by a supply channel (5). When the sand casting mold has two or more cavities, a single supply channel (5) can be coupled to a housing outlet (6o) and branch off toward different cavities, as illustrated in Figures 17a and 17c. Alternatively, several supply channels (5) can be coupled to corresponding housing outlets (6o), each leading to a different cavity, as illustrated in Figure 17b. Finally, as shown in Figure 15, several supply channels can be coupled to corresponding housing outlets (6o), with each supply channel branching off toward a different cavity. Vent channels (13) may be provided to vent the cavity as it is being filled with molten metal, maintaining a substantially constant pressure in the head space. The cavities (3) with corresponding feed channels (5) of the sand casting mold of the present invention are identical to those currently in use and are well known to those skilled in the art. Therefore, they will not be discussed in further detail subsequently.

[0079] Boa (7) The bore (7) extends from the bore inlet to the housing inlet (6i) over a bore length (d7). The bore portion, excluding the choke (7c), is preferably cylindrical, has a circular cross section, or tapers slightly in the flow direction, preferably with a taper angle of 2 degrees or less, more preferably 1 degree or less. The downstream end of the bore (87) is formed by a choke (7c), which forms a bore constriction that defines the bore outlet and reduces the bore diameter by at least 10% in the flow direction along the Z axis. The bore outlet opens to the housing inlet (6i). The choke (7c) allows pressure to build in the bore (7) so that the bore is completely filled with molten metal during the casting operation, reducing air entrapment and turbulence.

[0080] The bore walls can be formed by compacted sand, which forms the bulk of the mold (2), as illustrated in Figures 17a and 17e. This is the cheapest solution. However, the sand forming the bore walls can be eroded by the rapidly flowing molten metal, trapping sand particles in the housing (6) along with the molten metal. If the housing is equipped with a filter unit, the sand particles can be retained, but at the expense of pressure loss. To reduce or even avoid the risk of erosion, the bore walls can be lined with a lining (7s) over the entire bore length (d7), as shown in Figure 17b, or over only a portion of the bore length (d7), as shown in Figures 17c and 17g. The lining material must be cheaper than the refractory material forming the short shroud (9); otherwise, the material and cost savings achieved by using the short shroud would be offset by the additional material and cost required to form the lining (7s). The sole function of the lining (7s) is to prevent sand particles from eroding and becoming entrained in the metal flow. Any inexpensive material that forms an erosion-resistant compression surface during a single casting operation can be used to form the lining (7s). For example, chamotte (or grog), preferably composed of highly calcined clay, sand core material, or cellulose material can be advantageously used to form the lining (7s) because they are inexpensive and form a compression surface that is resistant to erosion by the flowing metal. In an alternative embodiment, the bore (7) features a dual-material lining approach. Specifically, the downstream segment of the bore length (d7) is lined with a first material, as depicted in the lining (7s). In contrast, the upstream segment of the bore length (d7) is lined with a second material (7m) that is characterized by higher dimensional accuracy compared to the first material. This dual-material lining configuration is illustrated in Figures 17d, 17f, and 17h. The primary role of the second material (7m) is to ensure an effective seal in the gap between the short shroud (9) and the bore (7). This second material is not limited to a particular type and may include a variety of substances such as foundry sand, ceramic, or core sand.An important criterion for selecting this material is its ability to be dimensionally accurate enough to ensure an optimum seal.

[0081] Housing(6) The housing (6) is in fluid communication with the bore outlet, allowing molten metal to flow directly from the bore (7) through the bore outlet and the housing inlet (6i) into the housing (6). Like a manifold, the housing (6) can be a diverter that directs the flow of molten metal toward the feed channels (5) that lead to the corresponding cavities (3). The housing also helps stabilize the flow of molten metal, eliminating turbulence and resulting in a more laminar flow before filling one or more cavities (3).

[0082] Preferably, the housing (6) is a filter housing provided with a filter unit to prevent solid particles from entering the feed channel (5) and the mold cavity (3), as illustrated by the checkered elements of the housing (6) in Figures 17a to 17c.

[0083] Sand Casting Mold Assembly The present invention also relates to a mold assembly comprising a mold (2), a mold / shroud coupling mechanism (14), and a short shroud (9) as defined above, wherein the shoulder base (11) of the short shroud (9) is seated on the seat member (16) of the mold / shroud coupling mechanism (14), and the downstream end (10d) of the short shaft (10) is inside the bore (7) and outside the housing inlet (6i). This configuration of the sand casting mold assembly is suitable for performing a casting process such as that illustrated in Figure 1, in which the short shroud (9) is first coupled to the sand casting mold (2) via the mold / shroud coupling mechanism (14). The shroud base (11) is generally located outside the mold, i.e., above and adjacent to the upper surface (8) of the mold, and the short shaft (10) is engaged within the bore (7). In the rest position, the downstream end of the short shaft is a given distance away from the housing inlet. If the mold / shroud coupling mechanism does not allow any movement of the short shroud along the Z-axis when the shroud base (11) is seated on the seat member (15), the given distance is d710, and the short shroud is in the shroud casting position. If the two types of mold / shroud coupling mechanisms (14) described above (one with a flexible element (17) and one with a lift mechanism) allow the short shaft to move up and down relative to the bore (7) between the rest position (h0) and the casing position (h1), the given distance is d710 ± |h0-h1|. As described above, the short shroud can be moved to the shroud casting position with the downstream end (10d) of the short shaft (10) at the shaft-free distance (d710) from the housing inlet (6i), i.e., If the mold / shroud coupling mechanism (14) comprises a flexible element (17), by applying a load along the Z axis towards the sand casting mold (2) to reduce the distance to d710, or • If the mold / shroud coupling mechanism (14) is equipped with a lift mechanism, by rotating the inner collar to increase the distance to d710.

[0084] In the shroud casting position, as shown in Figure 5, the short shaft is spaced from the housing inlet (6i) by a shaft-free distance d710. Molten metal is supplied to the casting cavity (3) through a flow passage extending from the ladle (103) to the casting cavity, flowing sequentially through the short nozzle of the nozzle (12), the short shroud (9), the bore (7), the housing (6), and the feed channel (5) before entering the cavity. As with the cited prior art long shroud, the flow passage is substantially airtight, preventing reoxidation of the metal by protecting it from the atmosphere. The bore (7) extends along the Z axis and is sized to receive the short shroud (9) with as narrow a gap as possible between the bore wall and the short shaft while still allowing linear movement of the short shroud (9) within the bore (7) along the Z axis. As explained above, when the bore (7) is filled with molten metal, some flows through the narrow gap and freezes or solidifies upon contact with the cold sand casting mold material, thus creating a sealed joint. Optionally, a joining material can be applied as a paste or gasket to ensure a perfect seal between the short shaft (10) and the bore wall.

[0085] In one embodiment of the mold assembly according to the present invention, the short shroud (9) is secured to the seat member (15) either by gravity or by a filler of molding sand (22) that fills the annular gap between the shroud base (11) and the seat member (15) and defines a seat for the shroud base (11), as illustrated in FIG.

[0086] In a preferred embodiment of the present invention, a gasket is disposed within the shroud inlet 9i to enhance the sealing contact between the nozzle 12 and the shroud inlet 9i. The gasket may be formed, for example, from plasticized clay or from an expandable material.

[0087] Casting Equipment The present invention also relates to a casting apparatus comprising a sand casting mold (2), a short shroud (9), a mold / shroud coupling mechanism (14), and a ladle (103) with a nozzle (12) provided at the base of the ladle (103) for dispensing molten metal from the ladle. The nozzle (12) is configured to reversibly and sealingly engage a shroud inlet (9i). The ladle (103) is configured to position the nozzle (12) substantially vertically (along the Z-axis) above the mold / shroud coupling mechanism (14) and the bore inlet (9i), and to be displaced relative to the sand casting mold (2) so that the nozzle (12) is lowered vertically along the Z-axis with the shroud (9) in the shroud casting position until the nozzle (12) sealingly engages within the shroud inlet (9i). Depending on the type of mold / shroud coupling mechanism (14) used, the short shroud (9) may already be in the shroud casting position before the nozzle (12) engages the shroud inlet (6i), or it may be brought to the shroud casting position by applying a load along the Z axis to the seat member (15) to deform the flexible element (17) or by rotating the inner collar to activate the lift mechanism. The casting apparatus may preferably include a gasket located within the shroud inlet (9i). In the casting apparatus, the short shroud (9) may be fixed to the seat member, preferably with a filler (22), or may be detachable and removable from the seat member (15).

[0088] To enhance sealing contact between the nozzle 12 and the shroud inlet 9i, the nozzle tip and the shroud inlet 9i preferably have mating male-female geometries. For example, the nozzle 12 can have a protruding frusto-conical geometry, and the shroud inlet 12 has a mating frusto-conical cup shape, as shown in Figures 3, 4, and 7a. Alternatively, the nozzle 12 can form a protruding spherical cap, and the shroud inlet 9i forms a spherical cup, as shown in Figures 5 and 6. These types of male / female geometries allow for moderate tilting of the nozzle relative to the short shroud 9. These geometries are also self-centering, compensating for any small deviations from nozzle alignment relative to the short shroud 9.

[0089] Applying a load to the interface between the nozzle and the shroud inlet (9i) is also important to ensure intimate contact. If a mold / shroud coupling mechanism with a flexible element (17) is used, the load can be applied when the ladle is lowered, engaging the nozzle tip into the shroud inlet (9i) and pressing the flexible element (17). If a mold / shroud coupling mechanism with a lift mechanism is used, the load is applied by lifting the shroud inlet (9i) above the nozzle top along the Z axis. The use of a flexible element is preferred because it reduces the risk of impact when the nozzle is lowered into the shroud inlet (9i) and can also absorb vibrations of the ladle and nozzle during the casting operation.

[0090] Ladle / shroud coupling mechanism (140) A preferred embodiment of the casting apparatus according to the present invention includes a ladle / shroud coupling mechanism (140) configured to reversibly grip the short shroud (9) to the nozzle (12), preferably without forming a seal between the shroud inlet (9i) and the nozzle (12).

[0091] As illustrated in Figures 2 and 9a, this allows the ladle to be moved with a short shroud suspended therefrom, which is advantageous when the shroud can be reused for multiple casts in succession, as illustrated, for example, in Figure 2. When a series of subsequent casts are made with the same ladle and shroud (9), the shroud can be disengaged from the bore of the first mold after completing the casting of the metal in the first mold, for example, by lifting the ladle (see Figure 2, step 4). The ladle is then translated horizontally to position the shroud over the bore of the second mold (see Figure 2, step 5). The ladle is then lowered downward (see Figure 2, step 1) until the shroud reaches the casting position (see Figure 2, (2)), and the subsequent cast can be made into the second mold. This operation can be repeated as long as the shroud remains in casting condition. The used shroud can then be removed (see Figure 2-Step 1b) and a new shroud can be loaded into the ladle (see Figure 2-Step 1a). This ladle / shroud coupling mechanism allows the same shroud to be used repeatedly for multiple castings. It also reduces the operator's workload because the coupling between the ladle, shroud, and mold can be performed by the operator alone, who commands the ladle positioning system. Between two castings using the same shroud, the shroud heated by the previous casting in one mold does not need to be manipulated by the operator to position it in the casting position in the subsequent mold, thus increasing safety.

[0092] Gripping the shroud to the nozzle, as described in PCT / EP2022 / 072007, can also be done with the long shroud of the cited prior art, but using a short shroud (9) instead has significant advantages in that the ladle does not have to be lifted high to remove the long shaft from the bore, and translating the ladle with the short shroud attached across the work area is easier and less dangerous than doing the same with a long shroud.

[0093] As shown in FIG. 9a, the ladle / shroud coupling mechanism (140) includes a base adapter (140b) secured to the shroud base (11) and equipped with a retaining means. The base adapter (140b) is typically made of metal and secured to the shoulder of the shroud with an adhesive filler (113), such as cement. The ladle / shroud coupling mechanism (140) also includes a nozzle adapter (140n) secured to the base or nozzle (12) of the ladle (103) and configured to engage with the retaining means of the base adapter (140b) to reversibly lock the short shroud (9) to the nozzle (12) in a locked position. The unlocked and locked positions of the ladle / shroud coupling mechanism (140) are shown in FIGS. 10 and 11, respectively. The ladle base is the lowest part of the ladle in use. The nozzle adapter (140n) is preferably attached to the base of a bottom-pour ladle.

[0094] The base adapter (140b) and the nozzle adapter (140n) are complementary and configured to releasably and loosely engage with each other in the locked position. One important aspect of the ladle / shroud coupling mechanism (140) according to the present invention is that the base adapter (140b) and the nozzle adapter (140n) are configured to loosely engage with each other in the locked position. This means that the shroud inlet (9i) and the nozzle adapter engage with each other in the locked position with sufficient play relative to each other so that they can articulate with each other to some extent. This design allows for relative movement between the short shroud and the ladle when the short shroud is attached to the ladle, significantly reducing the risk of damage to the shroud during insertion of the short shaft (10) into the mold bore (7). In the locked position, preferably, no sealing contact is formed between the nozzle and the shroud inlet (9i).

[0095] In a preferred embodiment of the ladle / shroud coupling mechanism depicted in Figures 10 and 11, the retaining means of the base adapter (140b) includes a retaining peg (109), and the nozzle adapter (140n) is provided with a fastening hook (107) configured to reversibly engage, and preferably self-engage, with the retaining peg (109). The self-engaging fastening hook allows the shroud to be easily gripped to the ladle. For example, this allows the ladle to be used to pick up a shroud held in a casting position in the first mold (2) according to the present invention, as illustrated in Figure 10, by lowering the ladle so that the retaining means of the base adapter engages with the nozzle adapter, as illustrated in Figures 11 and 15, and then the ladle can be lifted to remove the shroud from the bore, as illustrated in Figures 14 and 16.

[0096] Referring to FIG. 12, the base adapter (140b) may include a sleeve-like element having a truncated bearing surface (114) that rests on a beveled edge (115) within a central bore (25) of a seat member (15) that forms a seat for the base adapter (140b). The base adapter (140b) seats snugly on the seat member (15) but is held only by gravity. Two, three, or four retaining pegs (109) extend radially outward on the outer periphery of the base adapter (140b). The retaining pegs (109) may be engaged by fastening hooks (107) attached to a nozzle adapter (140n) that is attached to the ladle base plate (105).

[0097] The nozzle adapter (140n) is designed as a socket that surrounds the nozzle (12). At the side attached to the ladle (103), also referred to as the proximal side, the first coupling member (11) comprises a bayonet ring (106) that engages with the ladle base plate (105). The nozzle adapter (140n) is removably connected to the ladle (103). At the other end of the nozzle adapter (140n), also referred to as the distal end, the nozzle adapter (140n) comprises a number of studs (111) on which fastening hooks (107) are rotatably mounted.

[0098] During lowering of the nozzle 12 into the shroud inlet 9i, the nozzle adapter 140n and the base adapter 140b are engaged with each other. The coupling and locking of the nozzle adapter and the base adapter can be achieved in different ways. The fastening hook 107 can be self-engaging. The inclined surface 112 of the fastening hook 107 slides over the retaining peg 109 so that the fastening hook 107 captures the retaining peg 109.

[0099] Alternatively, the base adapter (140b) can be rotated so that the retaining pegs (109) are positioned between the fastening hooks (107) when the ladle (103) is lowered, and then upon rotation of the base adapter (140b), locking of the retaining pegs (109) in the fastening hooks (107) is achieved.

[0100] Once coupled as shown in Figure 13, the ladle (103) with the shroud (9) hanging thereon can be lifted for insertion into a second mold for a second casting using the same shroud.

[0101] In another embodiment of the ladle / shroud coupling mechanism (140), the retention means of the base adapter (140b) includes one or more retention pegs (109), and the nozzle adapter (140n) comprises a bayonet coupling element configured to interact with the one or more retention pegs to reversibly lock the short shroud (9) to the nozzle (12) in a locked position.

[0102] The nozzle adapter (140n) may be in the form of a sleeve-like member that may be configured as a bayonet coupling element at one and / or both ends. The nozzle adapter (140n) may enclose the nozzle and be releasably attached to the ladle base plate (105), as illustrated in Figures 12 and 13. For example, at one end, the nozzle adapter (140n) may be configured as a bayonet ring (106) that engages with a corresponding structure on the ladle base plate.

[0103] In one embodiment of the ladle / shroud coupling mechanism according to the invention, the base adapter and / or the nozzle adapter are rotatable about a longitudinal axis to allow at least disengagement of the base adapter and the nozzle adapter by rotating either the base adapter or the nozzle adapter about said longitudinal axis.

[0104] In the casting apparatus according to the present invention, the seat member 15 of the mold / shroud coupling mechanism 14 is configured to receive the base adapter 140b and hold the short shroud 9 when the short shroud 10 is inserted into the bore 7. The base adapter 140b is preferably fixed to the short shroud 9 with an adhesive material 113, as shown in FIGS. 12 and 13. Preferably, the outer wall of the shroud base 11 has a truncated conical shape, forming a shoulder 23 that rests on and is held by the adhesive material 113. The adhesive material may be filled or packed with molding sand and preferably contains a binder (organic or inorganic). The base adapter may be designed as a sleeve-like element.

[0105] Preferably, as illustrated in Figures 2(2a) and (2), the casting apparatus according to the present invention allows the ladle to be coupled to the short shroud (9) in situ, i.e., when the short shroud is inserted into the bore (7) of the sand casting mold. Therefore, a separate station for attaching the short shroud to the ladle, as shown in Figure 2(1a), is not required. The short shaft (10) of the short shroud (9) is first inserted into the bore, and the ladle is then lowered along the Z-axis, as described above with reference to Figures 1(1a) and (1), to engage the nozzle with the shroud opening (9i) and begin casting. In contrast to the embodiment of Figure 1, once the nozzle (12) is engaged with the shroud opening (9i), the base adapter (140b) and the shroud adapter (140n) can lock together to hold the short shroud (9) to the nozzle (12). At the end of a casting run, when the ladle is driven up and away from the sand casting mold (2), the short shroud (9), instead of remaining in the bore (7), is gripped by the nozzle and withdrawn along with the ladle, ready for use in the next casting run with a new sand casting mold (2). This operation can be repeated as long as the short shroud (9) is in good working condition. When the short nozzle becomes worn and must be disposed of, it is ungriped and discarded. A new short shroud (9) can be inserted into the next sand casting mold for the next casting run.

[0106] In existing technology, the so-called Harrison process, proposed by Harrison Steel Castings Company, involves installing a fused silica shroud under the nozzle of a bottom-pour ladle. The mold is provided with side risers to receive the shroud, which is provided with a pouring well below the side riser that flows into the casting cavity. Once the shroud is installed, the ladle is aligned over the mold and then lowered to insert the shroud into the side riser. The stopper rod is then moved to an open position, allowing the molten metal contained in the ladle to flow through the nozzle and shroud into the mold. Once the mold is filled, the stopper is closed. The ladle is then raised until the shroud clears the mold, and then the process is repeated for the next mold. To install the shroud under the nozzle of a bottom-pour ladle, the ladle is first secured to a mounting station, and the shroud is then fixedly attached to a shroud holder assembly connected to the ladle base plate.

[0107] One drawback of this rigid and fixed attachment of the shroud to the nozzle is that cleaning the nozzle by oxygen lancing is nearly impossible. Because the material chosen for the shroud is fused silica, inserting the shroud into the side risers of the mold while attaching it to the bottom of the ladle is a difficult and critical operation, as even the slightest tilt of the shroud can result in the shroud's destruction. Using a short shroud (9) instead is advantageous when moving the ladle around the workplace with the shroud protruding from its bottom.

[0108] Methods without ladle / shroud coupling mechanism (140) The present invention also relates to a method for casting molten metal using a casting apparatus according to the present invention. In a first embodiment of the method illustrated in Figure 1, the casting apparatus does not include a ladle / shroud coupling mechanism (140). The short shaft (10) of the short shroud (9) is inserted into the bore (7) with the shroud base (11) seated on the seat member (15) before the ladle approaches the mold. During use, the Z axis is substantially vertical. The short shroud (9) can be inserted into the mold (2) by an operator, as illustrated in Figure 1 (1a), or using one or more dedicated tools or robots. As illustrated in Figures 5 and 6, the shroud base (11) is seated on the seat member (15), and the short shaft (10) is inserted into the bore (7) with the downstream end (10d) of the short shaft (10) positioned a distance from the housing inlet (6i).

[0109] After step 1a of Figure 1, the mold assembly is ready to receive molten metal. 2 As illustrated in Figures 1(2) and 7a, a ladle (103) loaded with molten metal is transported (e.g., using a crane) onto a first sand casting mold (2) equipped with a short shroud (9), with the nozzle (12) aligned along the Z-axis with the shroud inlet (9i). The ladle (103) is then lowered until the nozzle (12) engages the shroud inlet (9i), as illustrated in Figures 1(2) and 7b. The short shroud (9) is brought to the shroud casting position by moving it a distance |h0-h1| along the Z-axis either by applying a load along the Z-axis to the flexible element (17) of the mold / shroud coupling mechanism (14) or by actuating a lift mechanism to lift the short nozzle into close contact with the nozzle, depending on the type of mold / shroud coupling mechanism used.

[0110] When the short shroud (9) is in close contact with the nozzle and in the shrouded casting position, as illustrated in Figure 1(3), metal can begin pouring into the mold. The nozzle is opened, thereby allowing molten metal to flow from the ladle (103) into the casting cavity (3) through the nozzle (12), the short shroud (9), and the housing (6) of the first sand casting mold. Once the casting cavity is full, as illustrated in Figures 1(3) and 1(4), the nozzle can be closed to stop the flow of molten metal, and the ladle can be withdrawn, ready to move over the next mold to begin a new casting run, as shown in Figures 1(5) and 1(1). The short shroud (9) remains inserted in the bore (7) of the first mold, not gripped by the ladle.

[0111] As shown in Figure 1 (6), the sand casting mold is broken to remove the cast metal part. The mold / shroud coupling mechanism (14) is also recovered for further use in a new mold. If the mold / shroud coupling mechanism is equipped with a lift mechanism or elastic elements, it can be directly reused without any further action. If the flexible elements are plastic or viscoelastic elements, it may be necessary to replace or reshape the flexible elements (17) before reusing the mold / shroud coupling mechanism.

[0112] The ladle is available for subsequent pouring into a second mold, as illustrated in Figures 1(5) and (1).

[0113] A method using a ladle / shroud coupling mechanism (140) In a second embodiment of the present invention illustrated in Figure 2, the casting apparatus includes a ladle / shroud coupling mechanism (140). The nozzle (12a) is provided with a nozzle adapter (140n), and a short shroud (9) with a base adapter (140b) is - inserted into the bore (7) as described with reference to the embodiment of Figure 1 and illustrated in Figure 2 (2a), or • As shown in Figure 2(1a) and explained above, it can either be fixed to the nozzle (12) by an operator or a robot.

[0114] The ladle (103a), with or without the short shroud (9), is moved (along the Z axis) with the nozzle (12) above the bore entrance; The nozzle (12) engages with the shroud inlet (9i) as shown in Figures 2(2a) and (2) and simultaneously the nozzle adapter (140n) grips the base adapter (140b), or The nozzle (12) with the locked short shroud (9) is either lowered to insert the short shaft (10) into the bore (7) until the shroud base (11) seats on the seat member (15) of the mold / shroud coupling mechanism (14) as shown in Figures 2(1) and (2).

[0115] At this stage, the short shroud (9) can be moved to the shroud casting position with the shroud inlet (9i) in intimate contact with the nozzle (12a) and the downstream end (10d) of the short shaft (9) at a shaft-free distance (d710) from the housing inlet (6i). If the mold / shroud coupling mechanism (14) comprises a flexible element (17), this is achieved by applying a load along the Z axis together with the nozzle (12) and ladle (103) to lower the seat member (15) and the short shroud (9) by a distance (h0-h1). If the mold / shroud coupling mechanism (14) comprises a lift mechanism, this is achieved by activating the lift mechanism (e.g., by rotating the seat member (15) (= inner collar) on the inclined surface of the base member (16) (= outer collar)) to lift the short shroud (9) by a distance (h1-h0).

[0116] As shown in Figure 2 (3), the nozzle is opened, allowing molten metal to flow from the ladle (103) into the casting cavity (3) through the nozzle (12), short shroud (9), and housing (6) of the first sand casting mold (2). Once one or more cavities (3) are filled with metal, as shown in Figures 2 (4) and (5), the nozzle is closed and the ladle (103) can be removed by lifting it away from the mold along the Z axis. Because the short shroud (2) is locked to the nozzle (12), the short shroud (9) is thereby ejected from the bore (7) and removed with the ladle, ready for use for the next casting operation or, if worn, ready to be dispensed.

[0117] As shown in Fire 2 (6), when the metal solidifies, the sand casting mold (2) can be destroyed to remove the metal part. The mold / shroud coupling mechanism (14) can be salvaged and reused in a new sand casting mold (2) after replacing or remolding any deformed plastic or viscoelastic elements, if necessary. The new sand casting mold can be used in a new metal casting process in accordance with the present invention (see Figure 2 (1) or (2a)).

[0118] Figure 2 shows how easy it is for the ladle (103) to advance across the work area with the short shroud (9) locked to the nozzle (12), as opposed to a ladle attached to the long shroud instead. Both the mold / shroud coupling mechanism (14) and the short shroud (9) can be recovered and reused for several other casting operations, thus significantly reducing the cost of the process. [Table 2-1] [Table 2-2] [Table 2-3]

Claims

1. A kit of parts for casting molten metal, comprising a short shroud (9), a sand casting mold (2), and a mold / shroud coupling arrangement, said short shroud (9) comprising: a shroud base (11) attached to the proximal end of a short shaft (10) having a shaft length (d10) measured along the Z axis; and a shroud bore extending along the Z-axis from a shroud inlet (9i) opening in the shroud base (11) to a shroud outlet (9o) opening in the downstream end (10d) of the short shaft; The sand casting mold is a casting cavity (3) having a cavity entrance (4); a housing (6) selected from a filter housing and a diverter housing, the housing (6) having a housing outlet (6o) in fluid communication with said cavity inlet (4) and a housing inlet (6i) in fluid communication with the bore (7); a bore (7) extending along the Z-axis over a bore length (d7) between a bore inlet opening in the upper surface (8) of the sand casting mold and a bore outlet opening at its downstream end at the level of the housing inlet (6i), the downstream end comprising a bore choke (7c); the bore choke (7c) reduces the bore diameter by at least 10% in the flow direction along the Z-axis to form a bore constriction defining the bore outlet opening into the housing (6); The mold / shroud coupling mechanism (14) a seat member (15) configured to receive the shroud base (11) and hold the short shroud (9) in a shroud casting position where the downstream end (10d) of the short shaft (10) is inserted into the bore (7); the shaft length (d10) is shorter than the bore length (d7) (i.e., d10<d7), so that, at the shroud casting position, the downstream end (10d) of the short shaft is spaced from the housing inlet (6i) by a shaft-free distance (d710) proportional to the bore length (d7) by a proportionality factor (k) (i.e., d710=kd7), the proportionality factor (k) being at least 20% (i.e., k≧0.2), more preferably at least 35% (i.e., k≧0.35); and the penetration depth (=d7-d710) of the short shaft (10) in the bore (7) at the shroud casting position is at least equal to 3 cm, more preferably at least equal to 5 cm, and most preferably at least equal to 10 cm; The mold / shroud coupling mechanism (14) a base member (16) fixed to said top surface (8); a seat member (15) configured to receive the shroud base (11) and hold the short shroud (9) in the shroud casting position; the base member (16) and the seat member (15) each have a central hole aligned with each other for introduction towards the bore (7) for the shroud (9); the seat member (15) is connected to the base member (16) by at least one flexible element (17), so that the seat member (15) is spaced from the base member (16) and is movable relative to the base member (16) from a seat rest position to a seat casting position upon application of a load parallel to the Z-axis to the seat member (15) that deforms the at least one flexible element (17) so as to drive a short shroud (9) seated on the seat member (15) to reach the shroud casting position; 10. The kit of parts, characterized in that said flexible element (17) comprises one or more elastic elements including a spring, preferably a spiral spring (17s), extending between said sheet member (15) and said base member (16).

2. 3. The kit of parts according to claim 2, wherein the mold / shroud coupling mechanism (14) preferably comprises at least three elastic elements, preferably at least three spiral springs (17s), extending between the seat member (15) and the base member (16), the at least three elastic elements preferably being equally spaced around the circumference of the central hole of the seat member (15) and the base member (16).

3. 3. A kit of parts according to claim 1 or 2, wherein the bore (7) is defined by a wall that is lined with a lining (7s) over at least a portion of the bore length (d7), preferably over the entire bore length (d7).

4. 4. The kit of parts of claim 3, wherein the lining material is selected from any one of chamotte composed of highly calcined clay, a sand core material, or a cellulosic material.

5. 1. A sand casting mold assembly comprising the short shroud (9) and the sand casting mold (2) as defined in any one of the preceding claims, wherein the shroud base (11) of the short shroud (9) is seated on the seat member (15) with the short shaft (10) of the short shroud (9) inserted into the bore (7) with the downstream end (10d) away from the housing inlet (5i).

6. The mold / shroud coupling mechanism (14) In the seat rest position, the downstream end (10d) of the short shaft (10) is maintained at a distance from the housing inlet that is greater than the shaft-free distance (d710); and 6. The sand casting mold assembly of claim 5, wherein, in the sheet casting position, upon application of the load parallel to the Z-axis, the downstream end (10d) of the short shaft (10) maintains the short shroud in the shroud casting position with the downstream end (10d) of the short shaft (10) spaced from the housing inlet by a distance substantially equal to the shaft-free distance (d710).

7. 1. A casting apparatus comprising: the short shroud (9) and the sand casting mold (2) as defined in any one of claims 1 to 4, a ladle (103) provided at the base of said ladle (103) with a nozzle (12) for dispensing molten metal from said ladle; The nozzle (12) is configured to reversibly and sealingly engage with the shroud inlet (9i) of the short shroud (9), and the ladle (103) is adapted to be, for example, to position the nozzle (12) over the mold / shroud coupling mechanism (14) in substantial alignment along the Z-axis; and the nozzle (12) is configured to be displaced downward along the Z-axis until the downstream end (10d) of the short shaft (10) engages the shroud inlet (9i) of the short shroud (9) in the shroud casting position outside the housing inlet (6i) and a shaft-free distance (d710) from the housing inlet (6i).

8. Preferably, the ladle / shroud coupling mechanism (140) is configured to reversibly grip the short shroud (9) to the nozzle (12) without forming a seal between the shroud inlet (9i) and the nozzle (12), and the ladle / shroud coupling mechanism (140) comprises: a base adapter (140b) fixed to the shroud base (11) of the short shroud (9), the base adapter (140b) comprising a retaining means; a nozzle adapter (140n) fixed to the base or the nozzle (12) of the ladle (103) and configured to engage the retaining means of the base adapter (140b) to reversibly lock the short shroud (9) on the nozzle (12) in a locked position.

9. The retaining means of the base adapter (140b) comprises one or more retaining pegs (109), and the nozzle adapter (140n) comprises: a fastening hook (107) configured to reversibly engage with said retention peg (109), preferably configured to self-engage with said retention peg (109); or A casting apparatus as described in claim 8, comprising either: a bayonet coupling element configured to interact with the one or more retaining pegs to reversibly lock the shroud (9) to the nozzle (12) in the locked position.

10. 10. The casting apparatus according to any one of claims 7 to 9, wherein the downstream end (10d) of the short shaft reaches the casting position at a shaft-free distance (d710) from the housing inlet (6i) by applying the load parallel to the Z-axis to the seat member (15).

11. A method for casting molten metal using a casting device according to any one of claims 7 to 10, comprising the steps of: lowering the ladle (103) along the Z-axis until the nozzle (12) is engaged in sealing contact within the shroud inlet (9i) and the short shroud, with the shroud base (11) seated on the seat member (15), is in the shroud casting position with the downstream end (10d) outside the housing inlet (6i) and spaced from the housing inlet (6i) by the shaft-free distance (d710); allowing the molten metal to flow from the ladle (103) to the casting cavity (3) through the nozzle (12), the short shroud (9), and the housing (6).

12. The casting apparatus according to claim 10, The method according to claim 11, wherein the ladle (103) is lowered along the Z-axis until the nozzle (12) engaging the shroud inlet (9i) applies a load parallel to the Z-axis to the shroud base (11) seated on the seat member (15), thus moving the seat member (15) along the Z-axis relative to the base member (16) against the flexible element (17), forming a sealing contact between the nozzle (12) and the shroud inlet (9i) of the short shroud (9) in the shroud casting position with the downstream end (10d) outside the housing inlet (6i) and spaced from the housing inlet (6i) by the shaft-free distance (d710).

13. the short shroud (9) is initially received within the sand casting mold (2) with the seat member (15) receiving the shroud base (11) and holding the short shroud (9) with the downstream end (10d) outside the housing inlet (6i) and at a distance from the housing inlet (6i) that is greater than the shaft-free distance (d710) to form a sand casting mold assembly according to claim 5 or 6; 13. The method of claim 12, comprising: lowering the ladle (103) vertically to engage the nozzle (12) with the shroud inlet (9i); and further lowering the ladle (103) for the nozzle (12) to apply the load to the shroud base (11), thereby forming the sealing contact between the nozzle (12) and the short shroud (9), and moving the short shroud (9) towards the housing inlet (6i) to the shroud casting position where the downstream end (10d) is spaced from the housing inlet by the shaft-free distance (d710).

14. The casting apparatus is as defined in claim 8 or 9, - engaging the nozzle (12) with the shroud inlet (9i) of the shroud (9); the retaining means of the base adapter (140b) fixed to the shroud inlet (9i) of the short shroud (9), Engage the nozzle adapter (140n) fixed to the base or the nozzle (12) of the ladle (103), gripping the short shroud (9) to the nozzle (12) using the ladle / shroud coupling mechanism (140), for example by locking the short shroud (9) to the nozzle (12) in a locked position; Positioning the short shroud (9) locked to the nozzle (12) on the mold / shroud coupling mechanism (14) in substantial alignment along the Z-axis; lowering the shroud base (11) along the Z-axis until it seats on the seat member (15) with the short shroud in the bore (7) and the downstream end spaced from the housing inlet (6i) by a distance greater than the shaft-free distance (d710); further lowering the ladle along the Z-axis until the short shroud reaches the shroud casting position where the downstream end (10d) is outside the housing inlet (6i) and is a shaft-free distance (d710) from the housing inlet (6i), whereby The method of claim 13, comprising forming the sealing contact between the short nozzle (12) and the short shroud (9).

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