WO2022144645A1

WO2022144645A1 - Vent duct for a casting channel of a gravity casting system

Info

Publication number: WO2022144645A1
Application number: PCT/IB2021/061502
Authority: WO
Inventors: Antonio Catalano; Roberto BARONI; Omar CAPELLI
Original assignee: Brembo S.P.A.
Priority date: 2020-12-29
Filing date: 2021-12-09
Publication date: 2022-07-07
Also published as: MX2023007820A; CN116887932A; EP4271529A1; IT202000032576A1

Abstract

The present invention relates to conveying ducts, known as "uprights", for a jet of molten metal in foundry molds. More specifically, the present invention relates to a conveying duct (1, ID for a casting channel of a gravity casting system, comprising a cylindrical outer surface (2, 12) with a lower edge (2a, 12a) and an upper edge (2b, 12b), and a cone-shaped longitudinal hole (4, 14) with downward flaring, extending between a surface (5, 15) at the upper edge (2b, 12b), and a lower opening (6, 16) at the lower edge (2a, 12a), characterized in that the outer surface (2, 12) comprises a flange (3, 13) at a distance (d) from the lower edge (2a, 12a).

Description

VENT DUCT FORA CASTING CHANNELOFA GRAVITY CASTING SYSTEM

DESCRIPTION

[0001]Technical field of the invention

[0002]The present invention relates to discharge ducts, known as "uprights", for a jet of molten metal in foundry molds.

[0003]Background art

[0004]The foundry processes for casting by gravity aluminum into a shell include using a mold made of a metal material, such as steel, cast iron, or bronze, in which a template representing a piece to be manufactured is obtained. The mold comprises one or more casting channels, depending on the shape and size of the piece to be manufactured, with which the so-called uprights are associated, forming discharge ducts for the jet of molten metal.

[0005] As shown in figures 1A and IB, the normally used upright configuration requires providing a seat in the mold on which the upright rests for supporting it. As is better shown in the enlarged view in figure IB, such a seat is geometrically fragile, with sharp edges and thin teeth which are prone to wear and easily damageable.

[0006]Damage to the seat or upright results in the formation of undercuts in the mold and thus in an interruption of the casting needed to arrange the mold. Furthermore, a heavy preventive maintenance action on the mold is required to keep the support teeth permanently intact.

[0007]On the other hand, a thickening or strengthening of such teeth causes the upright to move away from the jet, thus losing the feeding power. This results in an incorrect feeding of the jet with the onset of metallurgical problems, such as shrinkage cavities.

[0008] Furthermore, it should be noted that, unlike the upright which is generally made of a refractory material, the metal mold has a significantly lower insulating power, whereby the mold portion placed immediately below the upright and having sharp edges forms a surface for triggering the solidification of the casting molten metal. Such a premature solidification results in problems in the metallurgical quality of the manufactured piece.

[0009]Summary of the invention

[0010]The present invention aims to solve a two-fold problem: avoiding fragile points in the mold and avoiding cold points between jet and feeder.

[0011]This and other objects are achieved by an upright as outlined in claim 1 and in the dependent claims 2 to 5. [0012]In particular, the invention first relates to an upright or discharge duct for a casting channel of a gravity casting system, comprising a cylindrical outer surface with a lower edge and an upper edge and a cone-shaped longitudinal blind hole with downward flaring, extending between an upper surface and a lower opening arranged at the lower edge, characterized in that the outer surface comprises a flange at a distance d from the lower edge.

[0013]The invention further relates to a gravity casting system as outlined in claims 6 to 11.

In particular, the invention is further directed to a gravity casting system for a molten metal, in particular an aluminum alloy, comprising:

- an upper half-mold and a lower half-mold enclosing a template for a piece to be manufactured, preferably a caliper for disk brakes, where said template comprises one or more feeding chambers for the jet of molten metal;

- one or more casting channels at said feeding chambers of the template;

- a discharge duct as defined above, associated with each of said feeding chambers of the template, where said discharge duct is made of a refractory material; characterized in that the upper half-mold comprises a seat for said discharge duct, a suspension system of said discharge duct being placed in an intermediate position of said seat, and in that the discharge duct terminates at the bottom at the feeding chamber and the end portion of the seat of the discharge duct does not comprise edge or step profiles.

[0014]The text of the claims shall be considered included in the description for the purposes of evaluating the description sufficiency.

[0015]For a better understanding of the invention and for appreciating the advantages thereof, some nonlimiting exemplary embodiments thereof will be described below with reference to the accompanying drawings.

[0016]Brief description of the drawings

[0017]Figures 1A and 1B show sectional views of a detail of a foundry mold provided with an upright according to the prior art;

[0018]Figure 2 shows a partial perspective view of a foundry template with which a plurality of uprights according to the invention is associated;

[0019]Figure 3 shows a sectional view of a detail of a foundry mold with an upright according to the invention;

[0020]Figure 4 shows a perspective view of an upright according to the invention;

[0021]Figures 5A-5B show sectional views of two variants of the upright of the invention;

[0022]Figure 6 shows a plan view of the upright of the invention;

[0023]Figure 7 shows a phantom perspective view of the upright of the invention

[0024]Figure 8 shows a sectional view of a detail of a different embodiment of a foundry mold with an upright according to the invention.

[0025]Detailed description of the invention

[0026]For a better understanding of the invention, an upright according to the prior art will be first described in brief, with reference to figures 1A and IB. Such figures show a sectional detail of a mold of the conventional type, in which a conventional upright is inserted.

[0027]The mold consists of two half-molds, an upper half-mold Ms and a lower half-mold Mi, enclosing a template F of the piece to be manufactured.

[0028]The mold, made of a metal material, such as iron steel, cast iron, or bronze, or of sand, comprises, at the upper half-mold Ms, at least one seat C in which an upright M made of a refractory material is accommodated. The upright M is conveniently fixed inside the seat C by means of a cap MC.

[0029]The upright M is cylindrical in shape and comprises a cone-shaped longitudinal blind hole with downward flaring.

[0030]As is better shown in the enlargement in figure IB, the lower edge of the upright M rests on a shoulder SP obtained at the lower end of the seat C, which then widens again leading into a chamber V which will form the feeding chamber or riser and from which the casting moves to the template F.

[0031]As it can be seen, the portion of the seat C, at the shoulder SP, comprises a sharp edge profile. The assembly of shoulder SP and sharp edges placed at the bottom is easily damageable during the casting and further creates an easy solidification triggering area, which must strictly be avoided during this step of casting.

[0032]The invention solves the aforesaid problem, as shown below with reference to figures 2 to 8.

[0033]Figure 2 is a simplified view omitting the two half-molds and showing a template portion 100 with a plurality of feeding chambers 101 for the jet of molten metal (typically an aluminum alloy), with which an equal number of discharge ducts 1, also referred to as "uprights", is associated. By way of example, the template 100 represents a caliper for a disk brake, but the present invention is also applicable to other gravity casting templates.

[0034]Figures 3, 4, 5A, 6 and 7 depict an example of a discharge duct 1 of the invention.

[0035]In particular, figure 3 shows the discharge duct 1 mounted in a respective seat 104 of a mold comprising an upper half-mold 102 and a lower half- mold 103.

[0036]The seat 104 comprises a first portion 104a with a greater diameter, a second portion 104b with an intermediate diameter, and a third portion 104c with a smaller diameter, said portions 104a, 104b, 104c being joined by respective first and second shoulders 105a, 105b.

[0037]The discharge duct 1 has a cylindrical outer surface 2 with a lower edge 2a and an upper edge 2b. The outer surface 2 comprises a flange 3 at a distance d from the lower edge 2a. As it can be seen from figure 3, the flange 3 rests on the second shoulder 105b of the seat 104.

[0038]The discharge duct 1 further comprises a cone- shaped longitudinal blind hole 4 with downward flaring, extending between an upper surface 5 and a lower opening 6. [0039]The discharge duct 1 is held in place inside the seat 104 by means of a plate 106 resting on the first shoulder 105a and removably fixed thereto, for example, by means of a screw system 107.

[0040]The discharge duct 1 is made of a refractory material so as to minimize the heat exchanges with the metal mold and thus eliminate or drastically reduce the risk of solidification of the casting therein.

[0041]In the embodiment shown in the figures, the flange 3 consists of two projecting portions 3a, 3b which extend from diametrically opposite sections of the outer surface 2 of the discharge duct 1. The projecting portions 3a, 3b can have a square (figure 4) or semi-circular (figure 6) shape. Therefore, in such an embodiment, the sections of the outer surface 2 placed at 90° with respect to the projecting portions 3a, 3b have no projections.

[0042]This embodiment has a two-fold advantage. Firstly, it allows a lower consumption of refractory material, as the discharge duct 1 is obtained from a block by milling. Furthermore, considering that in one direction the duct 1 has no outer projections, it will be possible to place a greater number of discharge ducts close together in one mold, so as to improve the casting process. Additionally, such a geometry does not allow the rotation of the discharge duct 1 on its own axis.

[0043]However, in other embodiments, it will also be possible to provide a circular flange 3, thus protruding along the whole periphery of the duct 1.

[0044]Therefore, the discharge duct 1 is held inside the seat 104, on one side by means of the flange 3 resting on the respective shoulder 105b and on the other side by means of the plate 106 which presses the duct 1 downwards against the shoulder 105b.

[0045]Figure 5B shows a variant of the discharge duct. The discharge duct 11 is quite similar to the duct 1 shown in figure 5A, with the only difference that the distance D between the flange 13 and the upper edge 12b is greater, while the distance d between the flange 13 and the lower edge 12a is the same. Therefore, the longitudinal extension of the discharge duct 11 is greater than that of the duct 1. This allows keeping the distance between the second shoulder 105b and the outlet into the feeding chamber 101 constantly fixed in a mold, therefore the seat remains the same for both types of discharge duct (figs. 5A and 5B). The interchangeability of the uprights exclusively results in the geometry change of the fixing cap 106.

[0046]As shown in figure 8, the discharge duct 11 is held in place inside the seat 104 by means of a plate 206 comprising a flat portion 206a and a cylindrical portion 206b projecting downwards, so that the plate 206 has an upside-down U-shaped cross-section. The cylindrical portion 206b forms a support element of the plate 206 on the first shoulder 105a and is removably fixed thereto, for example by means of a screw system 107, as described above.

[0047]The flange assembly 3, 13 and respective shoulder 105b form a suspension system of the discharge duct 1, 11 inside the casting channel 104.

[0048]The invention further relates to a gravity casting system for a molten metal, in particular aluminum alloy, comprising:

- an upper half-mold 102 and a lower half-mold 103 enclosing a template 100 of a piece to be manufactured, preferably a caliper for disk brakes, where said template 100 comprises one or more feeding chambers 101 for the jet of molten metal;

- one or more casting channels at said feeding chambers 101 of the template 100;

- a discharge duct 1, 11 associated with each of said feeding chambers 101, where said discharge duct is made of a refractory material and has the features described above; characterized in that the upper half-mold 102 comprises a seat 104 for said discharge duct 1, 11, a suspension system of said discharge duct 1, 11 being placed in an intermediate position of said seat 104, and in that the discharge duct 1, 11 terminates at the bottom at the feeding chamber 101 and the end portion of the seat 104 of the discharge duct 1, 11 does not comprise edge or step profiles.

In particular, the seat 104 can comprise the features described above for such an embodiment.

[0049]As it can easily be inferred from the figures and the above description, the discharge duct 1, 11 of the present invention achieves the preset objects. [0050]In fact, having moved the suspension system of the upright to the intermediate position along the respective seat allows shaping the latter so as to avoid edge profiles in the lower portion thereof. In the lower part, the seat is cylindrical and smooth and opens out directly into the feeding chamber 101 of the casting.

[0051]Therefore, a premature solidification of the molten metal does not occur at the end portion of the seat, which may occur, instead, with the uprights of the prior art, since the conveying duct is entirely interposed between the seat 104 and the feeding chamber. Thereby, the feeding power and the material intake are better and the thus-manufactured pieces show no problems of shrinkage cavities.

[0052]The invention further allows reducing the times and costs of manufacturing and maintenance of the mold, avoiding excessive machine stoppages for maintenance, and reducing the percentage of waste material.

[0053]From the above description, in order to meet specific, contingent needs, those skilled in the art may make several changes or additions or can replace elements with others which are functionally equivalent, without departing from the scope of the appended claims. Each of the features described as belonging to a possible embodiment can be achieved irrespective of the other embodiments described.

Claims

1. A discharge duct (1, 11) for a casting channel of a gravity casting system, comprising a cylindrical outer surface (2, 12) with a lower edge (2a, 12a) and an upper edge (2b, 12b), and a cone-shaped longitudinal blind hole (4, 14) with downward flaring, extending between an upper surface (5, 15) and a lower opening (6, 16) arranged at the lower edge (2a, 12a), characterized in that the outer surface (2, 12) comprises a flange (3, 13) at a distance (d) from the lower edge (2a, 12a).

2. The discharge duct (1, 11) according to claim 1, wherein the flange (3, 13) consists of two projecting portions (3a, 3b) extending from diametrically opposite sections of the outer surface (2, 12).

3. The discharge duct (1, 11) according to claim 1 or claim 2, wherein the flange (3, 13) is circular.

4. The discharge duct (1, 11) according to any one of claims 1 to 3, wherein the distance (D) between the flange (3, 13) and the upper edge (2b, 12b) can have a different length, while the distance (d) between the flange (3, 13) and the lower edge (2a, 12a) is fixed.

5. The discharge duct (1, 11) according to any one of claims 1 to 4, said discharge duct being made of a refractory material.

6. A gravity casting system for a molten metal, in particular an aluminum alloy, comprising:

- an upper half-mold (102) and a lower half-mold (103) enclosing a template (100) for a piece to be manufactured, preferably a caliper for disk brakes, wherein said template (100) comprises one or more feeding chambers (101) for the jet of molten metal;

- one or more casting channels at said feeding chambers (101) of the template (100);

- a discharge duct (1, 11) according to any one of claims 1 to 5 associated with each of said feeding chambers (101), wherein said discharge duct (1, 11) is made of a refractory material; characterized in that the upper half-mold (102) comprises a seat (104) for said discharge duct (1, 11), a suspension system of said discharge duct (1, 11) being placed in an intermediate position of said seat (104), and in that the discharge duct (1, 11) terminates at the bottom at the feeding chamber (101) and the end portion of the seat (104) of the discharge duct (1, 11) does not comprise edge or step profiles.

7. The casting system according to claim 6, wherein the seat (104) comprises a shoulder (105b) configured to allow the flange (3, 13) of the discharge duct (1, 11) to be supported.

8. The casting system according to claim 6 or 7, wherein the seat (104) comprises a first portion (104a) with a greater diameter, a second portion (104b) with an intermediate diameter, and a third portion (104c) with a smaller diameter, said portions (104a, 104b, 104c) being joined by respective first and second shoulders (105a, 105b), wherein said second shoulder (105b) is configured to allow the flange (3, 13) of the discharge duct (1, 11) to be supported.

9. The casting system according to any one of claims

6 to 8, comprising a plate (106, 206) or a cap (MC) for retaining the discharge duct (1, 11) inside the seat (104).

10. The casting system according to claim 8, comprising a plate (106, 206) resting on the first shoulder (105a) and being removably fixed thereto, for example by means of a screw system (107).

11. The casting system according to claim 10, wherein the plate (206) comprises a flat portion (206a) and a cylindrical portion (206b) projecting downwards, said cylindrical portion (206b) forming an element for supporting the plate (206) on the first shoulder (105a).