INSERTABLE RISER BASE, SAND MOULD, MOULDING DEVICE CONSISTING OF THE INSERTABLE RISER BASE AND THE SAND MOULD, AND METHOD FOR PRODUCING THE MOULDING DEVICE

Abstract

The riser base is an insert obtained by manual moulding or by blowing having an insulating or exothermal composition. The composition includes hollow microspheres of aluminium silicate. The mould is mainly comprised of silica sand and presents a main cavity configured to be filled with molten metal to obtain a cast part and one or several auxiliary cavities. The insert fits into the auxiliary cavity made in the mould and presents an interior cavity configured to receive molten metal from a feeding riser or mini-feeding riser and an exterior geometry which coincides with the geometry of the aforesaid auxiliary cavity. The auxiliary cavity or cavities made in the mould itself are disposed in such a way that when the riser base is inserted into the auxiliary cavity, the interior cavity of the riser base is left in communication with the main cavity of the mould to allow passage of the molten metal.

Claims

1. A riser base insertable into a sand mould for casting metal parts, which comprises a main cavity configured to be filled with molten metal to obtain a cast part and at least one auxiliary cavity, wherein the riser base has an exterior geometry that allows the insertion of the riser base into the at least one auxiliary cavity of the mould, and in that the riser base further includes an interior cavity which communicates said main cavity of the mould with a feeding riser, when the riser base is inserted into the at least one auxiliary cavity, said riser base comprising an insulating or exothermal composition.

2. The riser base according to claim 1, wherein the insulating or exothermal composition comprises hollow microspheres of aluminium silicate and a binder, the hollow microspheres presenting an alumina content of equal to or less than 38% in weight.

3. The riser base according to claim 2, wherein the hollow microspheres present an alumina content of 20 to 38% in weight.

4. The riser base according to claim 2, wherein the insulating or exothermal composition comprises non-fibrous fillers, selected from the group formed by oxidable metals, oxidants, and inorganic fluorinated fluxes.

5. The riser base, according to claim 2, wherein the insulating and/or exothermal composition comprises cold or hot box curing binders.

6. The riser base according to claim 1, wherein the exterior geometry is prismatic, truncated pyramidal, cylindrical, or semi-spherical.

7. A sand mould for casting metal parts, configured to receive the incorporation of an insertable riser base provided with an interior cavity configured to receive molten metal from a feeding riser, wherein the sand mould comprises a main cavity which can be filled with molten metal to obtain a cast part and, at least, one auxiliary cavity with a geometry that allows the insertion of said riser base, the auxiliary cavity being disposed in respect to the main cavity in such a way that, when the riser base is inserted into the auxiliary cavity, the interior cavity of the riser base puts said main cavity of the mould in communication with a feeding riser, and in that the sand mould is made of silica sand.

8. The sand mould according to claim 7, wherein the interior geometry of the auxiliary cavity is prismatic, truncated pyramidal, cylindrical, or semi-spherical.

9. A moulding device formed by the sand mould according to claim 7, wherein said riser base is inserted into said sand mould.

10. A method for obtaining a moulding device for casting cast parts wherein the method includes the following steps: Obtaining a mould of silica sand which comprises a main cavity which can be filled with molten metal to obtain a cast part and at least one auxiliary cavity which presents a geometry that is configured to allow the insertion of a riser base; Obtaining the riser base having a composition of insulating and/or exothermal material, which comprises an interior cavity to receive molten metal from a feeding riser and an exterior geometry that allows the insertion of the riser base into the at least one auxiliary cavity of the mould. Inserting the riser base in the at least one auxiliary cavity of the mould, in such a way that the interior cavity of the riser base is in communication with the main cavity of the mould. Placing a feeding riser on the riser base, in such a way that the interior of the riser is in communication with the interior cavity of the riser base.

11. The method according to claim 10, wherein the riser base comprises an insulating or exothermal composition which comprises hollow microspheres of aluminium silicate and a binder, the hollow microspheres presenting an alumina content of equal to or less than 38% in weight.

12. The method according to claim 11, wherein the aluminium silicate presents an alumina content of 20 to 38%.

13. The method according to claim 11, wherein the riser base comprises non-fibrous fillers, selected from the group formed by oxidable metals, oxidants, and inorganic fluorinated fluxes.

14. The method according to claim 11, wherein the insulating and/or exothermal composition comprises a hot or a cold box cured binder.

15. The method according to claim 10, wherein the exterior geometry of the riser base and the interior geometry of the auxiliary cavity of the mould is of a prismatic, truncated pyramidal, cylindrical, or semi-spherical shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] To complement the description and with a view to contributing to a better understanding of the characteristics of the disclosure, in accordance with a preferred example of an embodiment thereof, a set of drawings is attached as an integral part of the description, which by way of illustration and not limitation represent the following:

[0080] FIG. 1 is a schematic representation of the elements which constitute a casting mould;

[0081] FIG. 2 describes the two ways of presenting the feed devices (in this case mini risers);

[0082] FIG. 3 represents a match plate used in the prior art to obtain a sand mould having a main cavity and a cavity or riser base;

[0083] FIG. 4 is a schematic representation of an insertable riser base, according to the present disclosure, ready to be inserted into a sand mould configured in accordance with the present disclosure to receive and house the insertable riser base;

[0084] FIG. 5 is a schematic representation of a moulding device which comprises an insertable riser base and a sand mould according to the present disclosure; and

[0085] FIGS. 6A and 6B are a comparative representation of a specific example to show what happens by replacing a traditional riser base with an insertable riser base according to the features of the present disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

[0086] FIG. 1 represents a casting mould (1) which comprises a main cavity (2) corresponding to the part to be manufactured and which has been formed by the moulding tool (3). In the same stage of moulding the filling system (4) has been configured and the feed devices (5).

[0087] The filling system (4) communicates the exterior of the mould (1) with the main cavity (2) and is made up of the feeding riser, the distribution channels and the joins or attacks on the part.

[0088] The feeding system feeding system (5) is responsible for feeding the part, in other words, for offsetting the contractions that occur in the liquid-solid change. It is frequent to use mini risers with insulating and/or exothermal properties.

[0089] FIG. 2 represents two common shapes of feed devices (in this case mini risers). When the feed device (5) is situated on the top part of the part it is referred to as on top and in this case the riser base is not used. However, when the feed is on the side, it is essential to use cavities for the bases of the riser (6). The cavity corresponding to the riser base (6) is one more part of the mould and, for this reason, these cavities are formed by the moulding tools (3) themselves, with the same moulding material as the mould assembly (1).

[0090] FIG. 3 presents a moulding tool (3) or match plate used to obtain the main cavity (2) and the cavity that forms the base of the riser (6).

[0091] FIG. 4 represents an insertable riser base (7) according to the features of the disclosure. The insertable riser base (7) is an element obtained independently from the casting mould (1) and comprises an interior cavity (8) which can house molten metal for feeding the main cavity (2). A casting mould (1) has also been represented which comprises a main cavity (2) that reproduces the shape of the part to be obtained and an auxiliary cavity (9). The exterior geometry of the insertable riser base (7) is similar to the geometry of the auxiliary cavity (9), in such a way that the riser base (7) can easily be inserted into the auxiliary cavity (9).

[0092] FIG. 5 represents an insertable riser base (7) housed in the auxiliary cavity (9) of the mould (1) and a riser or mini riser (10) on the insertable riser base (7). As can be observed in the aforesaid FIG. 5 the interior cavity (8) is left in direct communication with the main cavity (2) of the mould (1) and with the riser, in such a way that the molten metal contained in the riser feeds the main cavity (2) of the mould (1). It is observed that the metal of the part, of the riser base and of the mini riser forms a unit, which from the thermal point of view must keep the corresponding relation. It can be appreciated that the material constituting the insertable riser base (7) is similar to or the same as that of the mini riser (10), as in both cases they must present insulating and/or exothermal characteristics, this material being different to that of the mould (1). It is observed that the riser base (7) is an insert in the mould (1), which fulfils the same function as those traditional riser base cavities made of the same mixture (silica sand) as the mould and obtained along with the cavity of the party.

[0093] FIGS. 6A and 6B help to visualise what actually happens in manufacturing cast components. FIG. 6A shows a riser base according to the usual techniques. As observed in FIG. 6A the size of the riser base is very large, if compared with the diameter of the riser itself. This disproportion is related to the thermal and physical characteristics of the material of the mould and of the riser. It is very obvious that the size of the riser base penalises performance, while at the same time it is possible to appreciate the enormous disproportion existing between it and the feeder itself. The replacement of the cavity of the riser base with a riser base having a similar material to that of the mini riser, allows the modification of the solidification models of the feed environment. By optimising the insulating behaviour and providing it with exothermal capacity, the thermal behaviour of the riser bases forming the features of the present disclosure is more favourable and, for this reason, the quantity of metal that both riser bases demand is totally different. In FIG. 6B it is possible to observe the size of the riser base according to the features of the present disclosure. Unlike the size of the riser base represented in FIG. 6A in 6B it adjusts to reality, given that said geometries have been designed and validated by means of the corresponding simulation studies.

[0094] In this text, the word comprises and its variants (such as comprising, etc.) should not be interpreted as excluding, in other words, they do not exclude the possibility of what has been described including other elements, steps, etc.

[0095] On a separate note, the disclosure is not limited to the specific embodiments described herein, and also encompass, for example, variants that may be embodied by the average person skilled in the art (for example, with regards to the choice of materials, dimensions, components, configuration, etc.), within the scope of that inferred from the claims.