FR2821775A1 - MOLDING APPARATUS WITH MOUNTING MANEUVER AND MOLD PLACEMENT - Google Patents

Abstract

A molding apparatus and shell molds for molding molten metallic materials. The molding apparatus comprises a mold (10) having a mold placing fixture (12) thereon, a molding apparatus (12), molding chamber (70) incorporating a molten product delivery device (80) from which the mold (10) receives a molten product, a positioner assembly (90) disposed in the molding chamber (70), and a manipulator mold (50a, 50b) for locating the mold (10) in the molding chamber with said mold placing fixture (12) cooperatively engaged with the positioner fixture for locating said mold (10) by compared to the molten product supply device (80). The invention applies in particular to precision casting in which the shell mold is formed by the so-called lost wax process.

Description

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 The present invention relates to a molding apparatus and shell molds for molding molten metallic materials.

 In carrying out precision molding operations, a precision shell mold made of ceramic is formed by the well-known lost-wax process in which a fleeting pattern (for example in wax) of the object to be molded is immersed. repeatedly in a slurry of fine ceramic powder, discharged from excess slurry, coated with coarse ceramic particles, and air dried until a precision shell mold is constructed on the model to a desired wall thickness of the shell mold. The motif is then removed from the shell mold by a heat or chemical treatment, leaving a raw shell mold which is then baked in an oven to develop a resistance of the mold in order to mold a molten metal or alloy inside. . To this end, the shell mold which has thus been baked is preheated in an oven or a chamber forming a mold heating oven and is then placed in an oven and a molding chamber where the molten metal or alloy is introduced into the shell mold. The shell mold is typically placed in an oven or molding chamber with a shell mold pouring cup located below a crucible for holding molten product from which the molten metal or alloy is "cast in source "or" spout "by tilting the crucible towards the underlying shell mold. US Patents 5,309,976.5,592,984, 5,931,214 and 6,019,158 describe precision shell mold molding apparatuses where a precision shell mold made of ceramic and preheated is placed in relation to a crucible in order to receive a molten metal or alloy therefrom.

 In a particular molding apparatus, a melting chamber is separated or isolated from the underlying mold receiving chamber by means of a valve

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 appropriate isolation, such as a slide valve, which allows a vacuum to be maintained in the melting chamber. An individual charge of metal, such as an individual ingot, is caused to melt under vacuum (pressure below ambient pressure) in the crucible located in the melting chamber above the mold receiving chamber. When the charge is determined to be at an appropriate molding temperature, an operator requests that a preheated mold be removed from the mold heating oven and placed in the vacuum chamber for molding.

For example, a mold manipulator manually removes a preheated mold from the mold molding oven and manually places the preheated mold on a molding pan below the melting chamber closed by the isolation valve which has been closed. After the isolation valve is opened towards the melting chamber, the preheated mold is lifted by an elevating device under the molding tank to a height previously selected in the melting chamber below the crucible. The crucible is then caused to pivot so as to pour the molten metal in the form of a stream of free molten metal into a frustoconical pouring cup of the preheated mold placed below in the melting chamber. The pouring cup has a simple frustoconical receptacle for receiving the stream of molten metal from the crucible and directing it into the mold to fill it. After filling the mold with the molten metal, the mold is lowered onto the mold pan by the lifting device and brought into the mold receiving chamber, and the isolation valve is closed. The mold filled with molten product can remain in the mold receiving chamber or be removed therefrom for solidification of the molten metal inside. This cycle is repeated to mold a plurality of preheated molds one at a time during a molding campaign.

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 In such molding campaigns, the manual positioning of the preheated mold on the molding pan located in the vacuum chamber results in variations in the alignment of the mold relative to the crucible in the melting chamber. This variation in alignment from one mold to the next is typically greater at the start of a molding campaign and also when there is a change in the mold used and / or in the product (molding) in progress. . As molds are molded during a campaign, adjustments can be made by the mold manipulator until a position of the preheated mold close to the optimal is obtained constantly during the rest of the campaign. However, when "just in time" manufacturing procedures are adopted, shorter molding campaigns are used so that the problem of misalignment of the molds relative to the melting crucible becomes more troublesome.

 The variation in alignment from one mold to the next during a molding campaign adversely affects the alignment of the stream of molten metal poured from the crucible into the pouring cup of the respective molds. Such misalignment produces, for example, splashes of molten product because the pouring cup becomes cluttered with molten metal due to the misalignment. We then observe short installments and lower mold entry efficiency. In addition, such misalignment produces swirling of the metal in the pouring cup, which increases the residence time of the molten product in the relatively cooler pouring cup, thereby producing loss of thermal energy and resulting cold closures. as well as defects of cooled grains in the molding, and this decreases the axial kinetic energy of the stream of molten metal, by varying the filling time of the mold and in

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 decreasing the laminar flow of the metal while increasing the turbulence of the metal inside the mold. Turbulence inside the mold can cause the molten metal flowing to form swirls, reducing the pressure and speed of the metal, and this results in poor feed into the thin parts of the mold as well as the formation of oxides which leads to the formation of impurities or grime. Variations in the mold filling pattern from one mold to the next can increase the porosity of the moldings made during a particular molding campaign.

 The US patent application filed under number 09/255 187 and under examination describes a shell mold pouring cup the wall of which comprises a plurality of anti-swirl ribs spaced circumferentially from one another around the periphery of the pouring cup so as to reduce the swirling of the molten metal poured into the pouring cup due to poor alignment between the pouring cup and the pouring container.

 There is thus a need to improve the control of the operation and of the alignment of a precision shell mold relative to a crucible of molten material, or other container for supplying molten product, placed in a molding oven.

 The object of the present invention is to satisfy this need.

 The present invention creates, in one embodiment taken by way of illustration, a precision shell mold having a mold positioning assembly by which the shell mold can be maneuvered and moved by a mold manipulator between a mold heating chamber and a molding chamber. The mold manipulator sets up the preheated mold in the molding chamber in order to cooperate

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 with a positioner assembly arranged in the molding chamber. The positioner mounting of the chamber orients the preheated mold in a predetermined position relative to a device for supplying molten product, such as a container for supplying molten product, into the molding chamber so as to receive the molten product.

 The mold positioning assembly can be an integral part of the shell mold and can be adapted to be engaged by a manual or robotic mold manipulator, such as for example a mold sampling tool. The molding chamber may comprise a molding oven with the oven which has a positioner assembly inside and on which the mold placement assembly is placed to orient the shell mold relative to the crucible of molten product in the molding oven in order to place the mold in a predetermined orientation for receiving molten product from the crucible. Alternatively, a movable lifting piston located in the molding chamber can, for the same purpose, incorporate a positioner assembly.

 The molding apparatus according to the invention is thus characterized in that it comprises a mold having thereon a mold placement assembly, a molding chamber incorporating a device for supplying molten product from which the mold receives a molten product, a positioner assembly disposed in the molding chamber, and a mold manipulator for placing said mold in said molding chamber, with said mold placement assembly engaged cooperatively with the positioner assembly located in the molding chamber for positioning said mold relative to the device for supplying molten product.

 The invention will be better understood and other objects, characteristics, details and advantages thereof will appear more clearly during the description.

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 Explanatory which will follow made with reference to the appended schematic drawings given only by way of example illustrating an embodiment of the invention and in which: FIG. 1 is a schematic perspective view of a shell mold contained in an oven mold heating, the shell mold having a mold placement assembly in accordance with an embodiment of the invention for engagement by a mold grip tool; - Figure 2 is a schematic perspective view of the shell mold placed on a positioner assembly in a molding chamber for positioning the mold relative to a container for supplying molten product brought to communicate with the molding chamber; - Figure 3 is a schematic plan view of the mold placement mounting elements disposed on the positioner assembly in the molding chamber; - Figure 4 is an end elevation of a mold placement mounting member formed on the shell mold according to one embodiment of the invention; - Figure 5 is a schematic perspective view of a set of patterns used to make the shell mold by the molten wax process; - Figure 6 is a schematic perspective view of a lifting piston located in a molding chamber having a positioner mounting for positioning the mold relative to a container for supplying molten product brought to communicate with the molding chamber ; - Figure 7 is an exploded schematic perspective view of a shell mold on a positioner assembly placed on a lifting piston in a molding chamber to set up the mold

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 with respect to a container for supplying molten product brought into communication with the molding chamber; - Figure 8 is a schematic plan view of the preheated mold located on the positioner assembly placed on the lifting piston; - Figure 9 is a schematic perspective view of a shell mold according to another embodiment of the invention; and - Figure 10 is an exploded schematic perspective view of a shell mold for placement on a positioner assembly according to another embodiment of the invention on a lifting piston in a molding chamber to set places the mold relative to a container for supplying molten products brought into communication with the molding chamber.

 Referring now more particularly to FIGS. 1 to 4, these diagrammatically illustrate a molding apparatus for molding a molten metal or alloy (hereinafter called molten metallic material) in a shell mold precision made of ceramic 10 in a chamber 70 forming a molding oven. The shell mold 10, as illustrated, comprises a frustoconical pouring cup 10a which is an integral part thereof and which is connected to a main mold body 10b having one or more internal mold cavities 10c (only one of which is shown). A pouring nozzle 10d having an internal passage 10e connects the pouring cup 10a and the molding cavity 10c in such a way that the molten metallic material located in the pouring cup 10a flows into the molding cavity 10c. The mold cavity 10c has the shape of an object to be molded. For example, in Figure 1, the molding cavity 10c may have the shape of a turbine wheel.

 According to an embodiment of the present invention, the shell mold 10 comprises

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 also a mold fitting assembly 12 which comprises first and second elongated fitting mounting elements in the form of rod 12a secured to the outside of the pouring cup 10a. Each rod-shaped mounting element 12a preferably has a flat bottom surface 12b, FIG. 4. The remaining peripheral surface 12c of each mounting element 12a can have a curved shape, or any other shape such as a polygonal shape, or even a round shape. The rod-shaped mounting elements 12a are of equal length and are disposed on opposite diametric sides of the pouring cup 10a in a common horizontal plane and substantially parallel to each other in the common plane. The flat lower surfaces 12b of the mounting elements 12a collectively define a horizontal reference positioning plane or a platform by which the shell mold 10 can be removed, moved and put in place using a mold handling manipulator tool or the like 50.

 The mold 10 is produced using a set of fugitive patterns in wax or the like 20 illustrated in FIG. 5 with fugitive parts (for example, in wax) 20a, 20b, 20d and rods 22 corresponding to the pouring cup 10a, to the main mold body lOb, to the casting nozzle lOd and to the mold placement mounting elements 12a. The wax rods 22 comprise first and second solid fugitive rods (for example in wax) which are welded with wax, integral with the outside of the opposite diametrical sides of the pouring cup portion 20a of the set of patterns, or otherwise fixed on it, in order to constitute the mounting elements 12a. The wax rods 22 can be injection molded integrally with the pouring cup of all of the patterns 20, or preformed and fixed by welding with wax to all of the wax patterns 20. Alternatively, the wax rods 22 can be

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 fixed to the pouring cup 10a after application of one or more layers of ceramic on all of the patterns 20. The rods 22 can also be constituted by preformed rods made of ceramic or another refractory material caused to adhere to the cup for waxing all the patterns 20. The rods 22 are formed on the opposite diametrical sides of the portion of the pouring cup 20a or fixed thereon in a common horizontal plane and in a manner substantially parallel to each other. the other in the common plane to form the mounting elements 12a when all of the patterns are invested in the shell mold 10. Each rod 22 will have a flat bottom surface 22b and a curved surface (or of another shape) 22c complementary to the surfaces 12b, 12c of the mounting elements 12a.

 The shell mold 10 typically comprises a precision shell mold made of ceramic using the well-known so-called lost-wax process in which all the fugitive patterns (for example in wax) 20 are repeatedly immersed in a slurry of fine ceramic powder, discharged from excess slurry, coated with relatively coarse ceramic particles, and air-dried until a precision shell mold is made to a desired thickness of the shell wall on the motif.

All the fugitive patterns are then removed from the shell mold by a heat or chemical treatment, leaving the raw shell mold 10 which is then baked in an oven to develop an adequate resistance of the mold in order to mold inside. a molten metal or alloy. The wax process continues to produce shell molds is described in particular in US Patents 5,335,717 and 5,297,615 to which it is possible to refer. The ceramic materials used in the manufacture of ceramic slurry and in that of coarse ceramic particles

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 will be chosen in dependence on the particular metallic material to be molded in the shell mold and are not directly part of the present invention.

 After all of the patterns are removed, the raw shell mold 10 is baked or sintered in an oven (not shown) at a high baking temperature to develop sufficient strength of the mold for molding in the shell mold , a molten metallic material.

 In the preparation of a molding, the shell mold 10 which has been baked is preheated in a chamber 60 forming a mold heating oven, FIG. 1, and is then placed in a chamber 70 forming a molding oven, FIG. 2, where the molten metal or alloy is introduced into the shell mold 10 from a molten product holding container 80, such as a crucible of molten product 82. The chamber 60 forming the mold heating oven is shown separate of the chamber 70 forming a molding oven, FIG. 1, although the invention is not limited to this because the chambers 60 and 70 can be brought to communicate with each other. The preheated shell mold 10 can then be moved from the chamber 60 forming the mold heating oven to the chamber 70 forming the molding oven.

 According to the present invention, the shell mold 10 is moved by means of a mold gripping tool 50 which is illustrated as having a fork-shaped end with two branches 50a adapted to be placed around a nozzle. of casting 10d and in support engagement under the surfaces 12b of the mounting elements 12a for lifting and supporting the mold in preheated shell 10 during its transport to and out of the mold heating chamber 60 and then from the mold heating chamber 60 to the molding chamber 70. The tool 50 comprises an elongated tool arm 50b which can be operated by a robotic device

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 (not shown), or manually by a worker grabbing and operating the tool arm 50b.

The tool 50 can be made of steel or another suitable material.

 The shell mold 10 can be placed on a heat-resistant support plate T located in the chamber 60 forming the mold heating furnace using the tool 50, which is then removed from the furnace chamber 60 until the shell mold 10 is ready to be removed and moved to the molding chamber 70. The oven chamber 60 comprises a closable access door, (not shown) through which the shell mold 10 and the tool 50 can be moved to be brought into and out of the oven chamber 60.

 After the shell mold 10 is preheated in the chamber 60 forming the mold heating oven, it is withdrawn therefrom via the oven door using the tool 50 and it is transported using this tool 50, towards the molding chamber 70, FIG. 2, which has a positioner assembly 90 provided for engaging, supporting and positioning the mounting elements 12a of the shell mold 10 in order to orient it relative to the holding container of molten product 80 brought to communicate with the molding chamber. The molten product supply container 80 can comprise a molten product crucible 82 which can pivot around pins 82a, only one of which is shown, on the opposite sides of the crucible in order to pour the molten metallic material M located inside onto the lip 82b of the crucible and in the pouring cup 10a of the shell mold 10.

 The positioner assembly 90 includes spaced parallel side rails 92 each having a horizontal surface 92a and a vertical surface 92b. The surfaces 92a are coplanar to define a horizontal reference plane in a height direction H

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 relative to the container 80. The surfaces 92b are parallel to define respective vertical reference planes spaced from one another in a lateral direction L perpendicular to the direction H. The lateral (horizontal) distance between the vertical surfaces 92b is controlled to ensure the desired lateral orientation of the shell mold 10 relative to the container 80. Rear vertical surfaces 92c are provided on the rails 92 and are situated in a common vertical plane perpendicular to the plane which contains the surfaces 92a and to the plane which contains surfaces 92b in order to control and limit the movement of the mold in the direction of the depth D of the chamber 70.

 In particular, the planar lower surfaces 12b of the mold-fitting mounting elements 12a are placed by the tool 50 on the horizontal coplanar surfaces 92a between the vertical surfaces 92b, with the outermost lateral ends 12e of the mounting elements 12 near the surfaces 92b, or in abutment against them, and the rearmost element 12a near the surfaces 92c, or in abutment with them.

The tool 50 lowers the shell mold 10 on the positioner assembly 90. The shell mold 10 is thus placed at an appropriate vertical height in the direction H and is oriented in the directions L and D relative to the container 80 to provide precise control over the position of the shell mold relative to container 80.

 The positioner rails 92 can be mounted in the molding chamber 70 on the side walls 70a thereof using appropriate connecting elements made of steel or the like 97 fixed between the rails and the side walls, FIG. 2.

 As a variant, with reference to FIG. 6, the positioner rails 92 can be connected to a rear rail 94 which is fixed and supported by a vertical rail support element 93 fixed on a molding pan 95

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 which is arranged and fixed on top of a movable lifting piston R, FIG. 6. The rear rail 94 is disposed between the rails 92 and forms, in this embodiment, the vertical positioning surfaces 92c to control the positioning in place of the mold in the direction D. The surfaces 92a, 92b of the rail 94 are associated in a cooperative manner with the latter. The rail surfaces 92b control the positioning of the mold in the direction L. The lifting piston R is movable from top to bottom and from bottom to top in the chamber 70 to move the mold 10 on the positioning rails 92 while advancing it and moving it away from the container 80 in order to control the positioning of the mold in the direction H.

The molding chamber 70 comprises an access door of the traditional type, not shown, which is open to allow the positioning of the shell mold 10 on the positioner assembly 90.

 After the shell mold 10 is placed on the positioner assembly 90 in the molding chamber 70, the tool 50 is released and removed from the mounting elements 12a, leaving the shell mold 10 to rest on the container 80 in the chamber 70 and be set up in relation to it. The access door of the chamber can then be closed and closed to allow the melting of the metallic material under vacuum or under an atmosphere of inert gas in the chamber 70 and the subsequent pouring of the molten metallic material from the container 80 into the shell mold 10 suitably placed for this purpose with respect to the container 80 using the positioner assembly 90.

 The chamber 70 forming a molding furnace may comprise an optional isolation valve 100, such as a sliding slide valve which, when closed, will allow the metallic material M to be melted under vacuum (pressure lower than the ambient pressure), or under an inert gas atmosphere, in a melting chamber 75, while the preheated shell mold 10

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 is placed in the molding chamber 70 on the positioner assembly 90 below the isolation valve 100. The access door is then closed and closed to allow the molding chamber located below the isolation valve 100 to be evacuated at a pressure below ambient pressure, or to receive an inert gas atmosphere, before the isolation valve 100 is opened and the molten metallic material is poured from the container 80 into the shell mold 10 .

 If the lifting piston R is present in the chamber 70 forming the molding oven, FIG. 6, it can be moved upwards in the chamber 70 to move the shell mold 10 to a molding position near and below the container 80 After the shell mold is molded with the molten metal or alloy from the container 80, the piston R is lowered to lower the molded shell mold 10, which contains the metallic material M, to a lower position in the chamber. 70 forming a molding oven to be removed therefrom.

 The molded shell 10, which contains the metallic material M, can be removed from the chamber 70 forming a molding furnace at any suitable time before or after the solidification of the metallic material inside. An inert gas vacuum or atmosphere in the mold furnace chamber 70 can be replaced with ambient air so that the access door can be opened and the tool 50 can be moved into the chamber 70 and be engaged under the mounting surfaces 12b in order to lift the molded shell 10 from the positioner assembly 90 to be moved out of the chamber 70 for further processing.

 The present invention is advantageous for ensuring a uniform and precise positioning of successive shell molds 10 relative to the container 80 in the chamber 70 forming the molding oven. A

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 perfecting alignment from one mold to the next during a molding campaign will reduce splashes of molten product and short installments and improve the input efficiency of the mold. In addition, the swirling of the molten metal in the pouring cup will be reduced, which decreases the residence time of the molten product in the relatively cooler pouring cup, thereby reducing the loss of thermal energy, resulting cold closures. as well as the defects of cooled grains in the molding. Reducing such swirling in the pouring cup can reduce the variability in mold filling times and laminar metal flow and decrease the turbulence of the metal inside the mold.

 Although the mold placement assembly 12 and the positioner assembly 90 have been described with respect to first and second rod-shaped mold assembly elements 12a for placement on placement rails 92, the invention is not limited to this and can be put into practice using other configurations for mounting 12 of the mold and mounting positioner 90. For example, with reference to FIGS. 7 and 8 in which analogous features are represented by like reference numbers with a prime index, the 12 'mold set-up assembly, as shown, includes a 13' D-shaped set flange, formed on the mold pouring cup 10a 'to form an integral part thereof. The positioning flange 13 'comprises a laterally extending flat platform positioning part 13a' and an annular lip 13b 'around the pouring cup 10a'. The tool 50 'can be inserted under the lip 13b' in order to lift and move the mold 10 'from a mold heating oven, not shown but similar to that illustrated in FIG. 1, to a chamber 70' forming similar molding furnace

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 to that shown in FIG. 2. The positioner assembly 90 ′ comprises lateral positioner rails 92 ′ and a rear rail 94 ′ provided on a rail support element 93 ′ fixed to a mold pan 95 ′ which is arranged and fixed on the top of a movable lifting piston R ', Figure 7. The tool 50' sets up the preheated shell mold 10 'in the chamber 70' on the rails 92 'in such a way that the setting part place with flange 13a 'is received on a rail 92' (left rail in Figure 8) and the lip 13b 'is received on the other rail 92' (right rail in Figure 8) with the setting part flange place 13a 'received in the corner CI defined by the side rail 92' oriented perpendicularly and the rear rail 94 ', as shown. The molding of the mold 10 'thus placed is carried out as described above.

 In another embodiment of the invention illustrated in FIG. 9 in which similar characteristics are represented by similar reference numbers assigned to the double prime index, the assembly arrangement 12 '' of the shell mold 10 '' may include a flat plate-like element 15 '' provided on the pouring cup 10a ''. The tool 50 '' can be inserted under the element 1511 in order to lift and move the mold 10 '' from a mold heating oven, not shown but similar to that illustrated in FIG. 1, to the chamber forming molding furnace, not shown but similar to that illustrated in FIG. 2.

 The positioner mounting located in chamber 70 is not limited to the 92.94 (92 ', 94') rails discussed above, and may include other mounting configurations for receiving and placing places the assembly of the mold placement. For example, with reference to FIG. 10 in which similar characteristics are represented by similar reference numbers assigned a triple prime index, the positioner assembly 90 '' 'can

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 include a container or box 17 '' 'arranged and fixed on the lifting piston R' '' to set up the shell mold 10 '' 'in the chamber 70' ''. For example, a box 17 '' 'having an open top, positioning surfaces 17a' '', 17b '' 'and 17c' '', as well as a closed bottom 17d '' 'is shown as being placed on piston R '' 'in chamber 70' ''. The surfaces 17a '' ', 17b' '' and 17c '' 'have functions corresponding to the surfaces 92a', 92b ', 92c' in Figure 8. The surfaces 17a '' 'receive the positioning flange 13a above '' 'and the lip 13b' '' to cooperate with the surfaces 17b '' 'and 17c' '' in order to properly place the shell mold relative to the container for holding the molten product. The front and rear walls 17s '' 'may have a configuration necessary to allow the tool 50' '' to lower the mold 10 '' 'on the positioning flanges 17a' ''. Other configurations of boxes or containers are also possible.

 Furthermore, although a mold heating chamber 60 separate from the molding chamber 70 has been described, the mold heating chamber may be caused to communicate with the molding chamber. For example, in Figure 2, the mold heating chamber 60 can communicate directly with the molding chamber 70 through an access door, a passage or an opening therebetween. Furthermore, in FIG. 2, the molding chamber 70 can incorporate heating elements of the traditional type for preheating the shell mold 10 located inside, to a mold molding temperature before pouring, from the crucible , metal or metal alloy. In this embodiment, the molding chamber 70 also includes the mold heating chamber.

Claims (25)

1. Molding apparatus characterized in that it comprises a mold having thereon a fitting for placing the mold, a molding chamber incorporating a device for supplying molten product from which the mold receives a molten product, a mounting for positioning disposed in the molding chamber, and a mold manipulator for placing said mold in said molding chamber, with said mold placement assembly engaged cooperatively with the positioner assembly located in the molding chamber in place said mold relative to the device for supplying molten product.  2. Apparatus according to claim 1 characterized in that the mold placement assembly is an integral part of the shell mold.  3. Apparatus according to claim 2 characterized in that the mold placement assembly is an integral part of a mold pouring cup.  4. Apparatus according to claim 1 characterized in that the mounting of the mold comprises first and second coplanar elements on opposite sides of the pouring cup.  5. Apparatus according to claim 1 characterized in that the mounting of the mold comprises a planar element near the pouring cup.  6. Apparatus according to claim 1 characterized in that the device for supplying molten product is a crucible brought to communicate with the molding chamber.  7. Apparatus according to claim 7 characterized in that the crucible can be tilted to pour the molten product from it into the mold.  8. Apparatus according to claim 1 characterized in that the positioner assembly comprises first and <Desc / Clms Page number 19>  second parallel rails, each rail having a horizontal surface and a vertical surface.  9. Apparatus according to claim 8 characterized in that the horizontal surfaces are coplanar to define a horizontal reference plane in a height direction.  10. Apparatus according to claim 8 characterized in that the vertical surfaces are parallel to define vertical reference planes spaced from each other in a lateral direction perpendicular to the horizontal plane.  11. Apparatus according to claim 8 characterized in that the first and second rails cooperate with a vertical surface which controls the positioning of the mold in a direction perpendicular to the direction of the height and the lateral direction.  12. Apparatus according to claim 11 characterized in that the vertical surface is constituted by a third rail disposed between the first and second rails.  13. Apparatus according to claim 11 characterized in that said surfaces set up the shell mold at a vertical height and first and second lateral orientations relative to a container for supplying molten product.  14. Apparatus according to claim 1 characterized in that the mold manipulator comprises a mold-taking tool for engaging said mold-fitting assembly.  15. A method of molding molten metallic material, characterized in that it comprises the operations consisting in providing a mold having thereon a fitting for placing the mold and placing the mold in a molding chamber with said fitting for fitting in place of mold in cooperation engagement with a positioner assembly disposed in said molding chamber so as to orient the mold to receive molten metallic material. <Desc / Clms Page number 20>  16. The method of claim 15 characterized in that the mold positioning assembly is an integral part of the mold.  17. The method of claim 16 characterized in that the mold positioning assembly is an integral part of a mold pouring cup.  18. The method of claim 17 characterized in that the mounting of the mold comprises first and second coplanar elements on opposite sides of the pouring cup.  19. The method of claim 15 characterized in that the positioner assembly comprises first and second parallel rails, each rail having a horizontal surface and a vertical surface.  20. The method of claim 19 characterized in that the positioner assembly comprises a vertical surface which controls the positioning of the mold in a direction perpendicular to the horizontal surfaces and to the vertical surfaces.  21. The method of claim 15 characterized in that it comprises having a container for supplying molten product to communicate with the molding chamber.  22. The method of claim 21 characterized in that the positioner assembly sets up the mold in a predetermined position relative to the container for supplying molten product.  23. The method of claim 15 characterized in that it comprises lifting, using the mold manipulator, the preheated mold.  24. The method of claim 23 characterized in that it comprises lowering the preheated mold on the positioner assembly in the molding chamber.  25. Process for molding molten metallic material, characterized in that it comprises the steps consisting in: <Desc / Clms Page number 21>  preheat a mold in a mold heating chamber, engage a mold manipulator with a mold placement fixture disposed on the mold, move the preheated mold using the mold manipulator from the mold heating chamber to a molding chamber comprising a container for supplying molten product, placing the preheated mold in the molding chamber with the mold positioning assembly engaged in a cooperative manner, with a positioning assembly in the molding oven so placing the preheated mold at a vertical height and in a lateral orientation relative to the container for supplying molten product, and transferring the molten metal material from the device for supplying molten product to the preheated mold.