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(11) | EP 4 501 487 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | CASTING FEEDER |
| (57) It is provided a sleeve for sprue (1) comprising: retaining walls (2), an internal
volume (3) defined by the retaining walls (2), the retaining walls (2) defining a
connection portion (20) with a main mould (100) and a main portion (21), the main
portion (21) defining a portion of internal volume (3) having a substantially tubular
shape defining a central axis (21a), the retaining walls (2) in the main portion (21):
define an outer wall (22) defining a first mean diameter d, comprise protuberances
(23) protruding from said outer wall (22) towards the interior of the internal volume
(3), the protuberances (2b) protrude by a value between 0.1 d and 0.5 d and extend
predominantly in the axial direction (21a).
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[0001] The present invention relates to a sleeve for sprue, in particular for foundry use of the type specified in the preamble to the first claim.
[0002] The sprues used, in particular, in metal foundry processes and, more particularly, in ferrous material foundry processes, are currently known.
[0003] As is well known, liquid metal has a larger volume than solid metal, as do the vast majority of materials.
[0004] As a consequence, when metal solidifies from a liquid state, it includes shrinkage volumes or cavities that do not allow the metal to maintain the same shape as it had when it was in a liquid state. The latter coincided, of course, with the shape of the container in which the liquid metal was placed.
[0005] Consequently, in order to allow the solid metal to be shaped exactly like a cavity of the desired form, and thus to make metal parts by casting, the moulds include a sacrificial portion within which the metal forms the said shrinkage cavities.
[0006] This sacrificial portion, present in the moulds, is called a sprue and is surrounded by mould walls called sleeve for sprue.
[0007] The sprue must therefore comprise the portion of liquid metal that solidifies last. It generally has a cylindrical shape with an inlet, to the non-sacrificial portion of the mould, of a truncated cone shape.
[0008] Following solidification of the metal, the sprue portion is separated from the non-sacrificial portion. Typically, this separation is achieved through an initial brittle fracture and subsequent machining.
[0010] In particular, the molten metal contained in the sprue has been melted, expending thermal energy at high temperatures, and will then be discarded.
[0011] This melting is therefore a waste of energy that one would like to avoid in any way. However, the sprue must have minimum dimensions that allow the shrinkage cavity not to enter the non-sacrificial portion of the mould, and also considering a safety margin for uncontrollable process variables.
[0012] In this situation, the technical task underlying the present invention is to devise a sleeve for sprue capable of substantially obviating at least part of the aforementioned drawbacks.
[0013] Within the scope of said technical task, it is an important scope of the invention to obtain a sleeve for sprue having a smaller volume than commonly used volumes.
[0014] It is also an important scope of the invention to achieve a sleeve for sprue which allows the entire shrinkage cavity to be contained within the non-sacrificial portion of the mould.
[0015] The specified technical task and purposes are achieved by a sleeve for sprue as claimed in the appended claim 1.
[0017] The features and advantages of the invention are hereinafter clarified by the detailed description of preferred embodiments of the invention, with reference to the appended drawings, in which:
Fig. 1 shows an axonometric view of a sleeve for sprue according to the invention;
Fig. 2 shows a side view of the mould walls of a sleeve for sprue according to the invention and a portion of the mould immediately below;
Fig. 3 shows a preferred scaled example of the sectional view III-III, shown in Fig. 2, of the die walls of the sleeve for sprue according to the invention; and
Fig. 4 shows a preferred scaled example of the sectional view IV-IV, indicated in Fig. 2, of the die walls of the sprue according to the invention.
[0018] Herein, measurements, values, shapes and geometrical references (such as perpendicularity and parallelism), when associated with words such as "approximately" or other similar terms such as "nearly" or "substantially", are to be understood as unless there are measurement errors or inaccuracies due to production and/or manufacturing errors and, more importantly, unless there is a slight deviation from the value, measurement, shape or geometrical reference with which it is associated. For example, such terms, when associated with a value, preferably indicate a deviation of no more than 10% of the value.
[0019] Furthermore, when used, terms such as "first", "second", "top", "bottom", "principal" and "secondary" do not necessarily identify an order, priority of relationship or relative position, but may simply be used to more clearly distinguish between different components.
[0020] Unless otherwise specified, as reflected in the following discussions, terms such as "processing", "computing", "determination", "calculation", or the like, are considered to refer to the action and/or processes of a computer or similar electronic computing device that manipulates and/or transforms data represented as physical quantities, such as electronic quantities of registers of a computer system and/or memories in, other data similarly represented as physical quantities within computer systems, registers or other information storage, transmission or display devices.
[0021] Measurements and data reported herein shall, unless otherwise indicated, be considered to have been made in ICAO International Standard Atmosphere (ISO 2533:1975).
[0022] With reference to the Figures, the sleeve for sprue according to the invention is globally referred to as number 1.
[0023] The sleeve for sprue 1 is subservient to a main mould 100, of a non-sacrificial type, defining an operating volume 100a having the shape of the part to be made. The main mould 100 and the sleeve for sprue 1 together form a complete mould 101.
[0024] The complete mould 101 is preferably for foundry use, more particularly for ferrous metal materials, such as steel and cast iron.
[0025] It is accordingly preferably made of compacted powders in insulating, isothermal or other materials known to them.
[0026] Said compacted powders preferably have the following preferred compositions. In a first example, they are exothermic powders and preferably comprise the following materials: Al2O3: 45%-50%; Al met: 23%-28%; SiO2: 15%-20%; Fe2O3: 3%-5%; Other < 5%.
[0027] In a second example, they are insulating powders and preferably consist of the following materials: Al2O3: 60%-65%; SiO2: 30%-35%; Fe2O3: 1%-3%; CaO <3%.
[0029] The sleeve for sprue 1 comprising retaining walls 2, preferably made of said refractory material and preferably integral with the walls of the main mould 100, and an inner volume 3 defined by the retaining walls 2.
[0031] The retaining walls 2 define a connection portion 20 with a main mould 100 and a main portion 21 of the mould, preferably constituting the majority of the internal volume 3.
[0034] The connection portion 20 is preferably of a per se known type. It defines a boundary surface 30 that virtually divides the internal volume 3 from the operational volume 100a. It is, moreover, preferably truncated cone-shaped with a minor base formed by said boundary surface 20a, it could also be cylindrical, cylindrical with oval cross-section or other.
[0035] The main portion 21, in turn, borders the connection portion 20 on one side, defining an internal surface 31, and the external environment on the other side, defining an external surface 32.
[0036] The inner volume 3, at the main portion 21 preferably defines a substantially tubular shape defining a central axis 21a, and with the inner surface 31 and the outer surface 32 preferably crooked and more preferably perpendicular to the central axis 21a.
[0037] Further preferably, the retaining walls 2 in the main portion 21 define an outer wall 22 and comprise protuberances 23 protruding from the outer wall 22 towards the interior of the inner volume 3.
[0038] The outer wall 22 preferably defines a first mean diameter d. The virtual extension of the outer wall 22, which in reality is interrupted by the protuberances 23, preferably defines a circular surface, more preferably a cylindrical surface, possibly with a diameter varying from the inner surface 31 to the outer surface 32, but preferably being constant.
[0039] The outer wall 22 also defines a surface s, virtual, which would coincide with the real surface if the protuberances 23 were not present.
[0040] Preferably, the protuberances 23 extend predominantly in the axial direction 21a and, more preferably, are parallel to said axial direction 21a.
[0041] Furthermore, the protuberances 23, preferably, extend along most of the outer wall 22, and more preferably along the entire length of said outer wall 22.
[0042] Furthermore, preferably, wherein said protuberances 2b have a section, in the plane perpendicular to the central axis 21a of rectangular shape, more preferably substantially square. Said section obviously has connections with the outer wall 22. The protuberances also define inner sides 23a whose ideal extension would make, in the section perpendicular to the central axis 21a a polygon, preferably regular, preferably with a number of sides between 4 and 16 depending on the size of the sprue, more preferably between 4 and 8.
[0043] Furthermore, preferably, the protuberances 23 decrease in circumferential thickness by moving away from said connection portion 20, as illustrated in the sections of Figs. 3 and 4. Preferably, this reduction is of linear dimensions of between 10% and 20% and provides for substantially unchanged proportions.
[0044] Dimensionally, preferably, the protuberances 23 protrude by an average value of between 0.1 d and 0.5 d, with d comprising the diameter of the outer wall 22 as cited. More preferably this value is between 0.1 d and 0.4 d, more preferably still between 0.2 d and 0.4 d, more preferably still between 0.25 and 0.35.
[0045] Further, the protuberances 23 occupy a surface area of the outer wall 22 between 0.3 s and 0.7 s, with s comprising the value of the ideal surface area of the outer wall 22 as cited. More preferably, this value is between 0.4 s and 0.6 s.
[0046] The operation of the sleeve for sprue 1, described above in structural terms, does not vary from the operation of known sprue types.
[0047] The sleeve for sprue 1 is in fact placed on the main mould 100 at the area that solidifies last.
[0048] When the liquid metal is inserted into the operating volume 100a of the main mould 100, the entire inner volume 3 of the sleeve for sprue 1 is also filled.
[0049] The liquid metal solidifies inside the main mould 100, forming the desired shaped part and remains liquid in the sleeve for sprue 1.
[0050] Thereafter, the liquid metal solidifies everywhere, including in the sleeve for sprue 1 inside which it forms a shrinkage cavity.
[0051] The part, including the sprue counter-mould, is extracted from the operating volume 100a. The sprue counter-mould is then removed, first roughly, for example by impact causing a brittle fracture at the boundary surface 30, and then by tooling.
[0053] In fact, tests of the applicant, have surprisingly shown that the volume of liquid metal inside the sleeve for sprue 1 remains liquid, and thus at temperature, for longer than the period of time during which the same volume of metal placed in a conventional, cylindrical, smooth-walled sprue would remain liquid.
1. Sleeve for sprue (1) comprising
- retaining walls (2)
- an internal volume (3) defined by said retaining walls (2),
- said retaining walls (2) defining a connection portion (20) with a main mould (100) and a main portion (21),
- said main portion (21) defining a portion of internal volume (3) having a substantially tubular shape defining a central axis (21a),
- and characterised by said retaining walls (2) in said main portion (21):
- define an outer wall (22) defining a first mean diameter d,
- comprise protuberances (23) protruding from said outer wall (22) towards the interior of said internal volume (3),
- said protuberances (2b) protrude by a value between 0.1 d and 0.5 d and extend predominantly in the axial direction (21a).
2. Sleeve for sprue (1) according to claim 1, wherein said outer wall (22) is cylindrical.
3. Sleeve for sprue (1) according to any one of the preceding claims, wherein said protuberances
(23) protrude by a value of between 0.2 d and 0.4 d.
4. Sleeve for sprue (1) according to any one of the preceding claims, wherein said outer
wall (22) defines an area s and said protuberances (23) occupy an area of said outer
wall (22) between 0.3 s and 0.7 s.
5. Sleeve for sprue (1) according to any one of the preceding claims, wherein said protuberances
(23) extend along the entire length of said outer wall (22).
6. Sleeve for sprue (1) according to any one of the preceding claims, wherein said protuberances
(23) decrease in circumferential thickness as they recede from said connection portion
(20).
7. Sleeve for sprue (1) according to any one of the preceding claims, wherein said protuberances
(23) have a section, in the plane perpendicular to the central axis (21a) of rectangular
shape.
8. Sleeve for sprue (1) according to any one of the preceding claims, wherein said protuberances
(23) have a section, in the plane perpendicular to the central axis (21a), of rectangular
shape.
9. Sleeve for sprue (1) according to any one of the preceding claims, wherein said connection
portion (20) is truncated cone-shaped and narrows away from said main portion (21).
10. Sleeve for sprue (1) according to any one of the preceding claims, configured for
metal foundry.