In particular, the present invention relates to a device for filling moulds aimed at forming the above mentioned metallic articles in an apparatus for centrifuged moulding.

DESCRIPTION OF PRIOR ART A lot of metallic articles produced by melting, usually having rather complicated shape and therefore, being difficult to produce, are advantageously obtained by making the melted metal penetrate inside suitable moulds, driven to rotate rapidly in a suitable apparatus, by the centrifugal force.

A particularly significant example of such articles is a metal structure for dental prosthesis, which supports the external portion of teeth in their exact implant position.

There are other types of such apparatuses.

A commonly used apparatus includes a substantially cylindrical basin, situated horizontally or vertically, which contains a rotating arm extending parallel to the basin bottom.

The arm is situated diametrically to the basin and is

hinged to a motorized shaft protruding from the basin bottom, in the region of the basin axis.

One end of the shaft carries a pot containing melted metal, a mould carrying device, and a mould, carried by the mould carrying device and aimed at receiving the melted metal from the pot.

The pot is substantially a container made of refractory material, with its upper part open.

The pot and the mould are situated along one basin radial direction, the former inner and the latter outer with respect to this direction.

The pot has a lateral hole, set in communication with a corresponding inlet mouth of the mould.

The hole of the pot and the mouth of the mould are oriented along the above mentioned radial direction.

The other end of the arm carries a counter-weight aimed at balancing the arm and at bringing its gravity center substantially in the region of the rotation axis.

A suitable quantity of metal in solid state is put into the pot and is made to melt by a heating device including an induction coil situated in the basin.

Afterwards, the arm is driven to rotate rapidly, with the maximum possible acceleration.

The melted metal contained in the pot is subjected to a progressively increasing centrifugal force, which acts in radial direction, oriented outward the basin.

The centrifugal force conveys the melted metal toward the hole of the pot and toward the mouth of the mould, which are oriented, as has been already said, in radial direction.

Therefore, the metal tends to enter the mould cavities in a particularly efficient and uniform way.

The mould filling operation must be carried out as quickly as possible to prevent the metal from cooling and solidifying.

Usually, the mould is filled after the centrifuge had rotated by much less than 90° (a quarter of a turn).

Another type of centrifuge device includes a surface, turning about an axis and aimed at being driven to rotate rapidly by a motor situated below.

The turning surface supports a mould and a casting pit, which communicate with each other along the radial direction and which are situated at a predetermined distance from the rotation center and in radial alignment.

An overturning melting pit, situated over the casting pit, is aimed at receiving a suitable quantity of metal in solid state.

An electric arc heating member is situated over the melting pit and makes the metal contained in the pit melt.

At this moment, the melting pit is turned, to cast the melted metal into the casting pit.

Then, the surface supporting the casting pit and the mould is immediately driven to rotate rapidly, with a strong acceleration.

The centrifugal force discharges the melted metal from the pit through the above mentioned communication channel and conveys it to the mould.

Obviously, in the above described devices, the earlier

the high rotation speed is obtained, the more rapidly the mould is filled.

Therefore, as high as possible acceleration is necessary at the start.

The known devices feature a disadvantage, which limits their efficiency.

Actually, the starting acceleration creates a very high tangential force, whose direction is opposite to the rotation direction. The tangential force acts on the still melted metal and pushes it against the inner wall of the container (pot or melting pit), to a position located backward with respect to the radial hole communicating with the mould.

Only when the centrifugal force becomes considerable, can the metal be conveyed toward the mould.

Thus, a good part of the metal does not reach the mould before solidification due to cooling.

The above described disadvantage is always present, but it is particularly important when metals like titanium are treated.

Actually, the titanium temperature interval required for the transition from the solid state to the liquid state is very limited, thus the metal passes very quickly to a state, in which it is completely unusable.

Other metals, like iron, tend to solidify, due to cooling, passing gradually through different states of always bigger viscosity, thus they can be used in a bigger temperature interval.

Therefore, in order to process titanium, it is necessary to accept considerable material scraps or to use centrifuges featuring much higher starting speed, whose

construction is consequently more complicated and expensive.

OBJECTS OF THE INVENTION The object of the present invention is to propose a device for filling moulds in a centrifuge apparatus, which avoids the above mentioned disadvantage and optimizes the use of all-the forces created by the device rotation and acting on the melted metal, thus allowing the moulds to be filled correctly and in a particularly short time.

Another object of the present invention is to propose an adjustable device, whose performance is always the best, in relation to the features of the used centrifuge.

SUMMARY OF THE INVENTION The above mentioned objects are obtained in accordance with contents of claims, by a device for filling moulds with melted metal in a centrifuge apparatus, said device being supported in said apparatus in a eccentric position by supporting means which are driven into rotation about a predetermined axis.

The device includes: a container for melted metal, situated at a distance from said rotation axis and having a hole for the melted metal outlet; a mould carrier, situated further from said rotation axis than said container and aimed at carrying a corresponding mould, said mould having an inlet mouth communicating with the

above outlet hole.

In particular, according to the proposed device, the outlet hole and the inlet mouth are angularly located backward with respect to the radial direction of the centrifugal force F, by a predetermined angle A.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristic features of the present invention, which do not result from what has been said, will be pointed out in the following description, with reference to the enclosed drawings, in which: -Figure 1 is a schematic top view of a melting basin of an apparatus for the centrifugal melting, equipped with the device proposed by the present invention ; -Figure 2 is a schematic lateral view of a pot joined to an induction heating device; -Figure 3 is a schematic lateral section view taken along line III-III of Figure 1; -Figure 4 is a section view of the pot of Figure 3, taken along line IV-IV of Figure 3.

DESCRIPTION OF PREFFERED EMBODIMENTS OF THE INVENTION With reference to Figure 1, and to one embodiment of the invention, the reference numeral 100 indicates a centrifugal apparatus for obtaining metal articles.

This embodiment, as far as the type of the apparatus 100

implementing the invention is concerned, is described as a mere example, and therefore the embodiment can be used in other known types of centrifugal apparatuses.

The proposed device could be used, without substantial changes, in other types of apparatuses, described before, or in other known apparatuses.

The apparatus 100 includes a horizontal, substantially cylindrical basin 1, which is accessible from top and can be covered with a cover, which is not shown.

An arm 2 is situated inside the basin 1, horizontally and substantially extending along a diametrical direction.

The arm 2 is fastened, at an intermediate position between the ends 2a, 2b thereof, by suitable fastening means 4, to a vertical shaft 3 protruding from the basin 1 bottom, in the region of the basin center.

The shaft 3 is driven to rotate in a direction W by known motor means, not shown.

Consequently, also the arm 2 is driven to rotate on a horizontal plane, about an axis X of the shaft 3, integrally therewith, in the same direction W.

The device for filling moulds 10, subject of the present invention, is joined to the end 2a of the arm 2.

According to a preferred, but not only embodiment, the moulds filling device includes a frame 11 featuring a transversal bar lla, fastened to the above mentioned end 2a.

A pair of horizontal prongs, substantially cylindrical, respectively fore llb and rear llc with respect to the rotation direction W, are fastened to the transversal bar lla.

The prongs llb, llc are situated symmetrically with respect to the axis of the arm 2, and substantially parallel thereto.

The prongs llb, llc support slidingly a plate 40 by a pair of ring-like guides 41a, 41b made on the sides of the plate 40.

A circular seat 42 is made in the plate 40, substantially symmetrical with respect to the arm 2 axis.

The circular seat 42 receives a container for melted metal 12, e. g. a pot (see also Figure 2).

The pot 12 forms a container, whose upper part is open and which is equipped with a cavity 15, narrowing at the lower section, and with an outer shoulder 12a, aimed at resting onto the plate 40.

The pot 12 is also equipped with a hole 13, made laterally in the upper part thereof, approximately in correspondence to the shoulder 12a.

An angular bracket 43, fastened to the free end of the fore prong llb, is aimed at cooperating with the rear prong llc to support a mould carrier 20.

The shape and characteristics of the mould carrier 20 are known and will not be described in detail as it is beyond the scope of the present invention.

The mould carrier 20 is supported by the bracket 43 and the rear prong llc, and is inclined in direction opposite to the rotation direction W, i. e. located backward with respect thereto.

A mould 30, situated inside the mould carrier 20, is aimed at receiving the melted metal from the pot 12 through an inlet mouth 31 (see also Figure 4).

The angular arrangement of the mould carrier 20, the position of the mould 30 inside the mould carrier 20 and the orientation of the pot 12 in the corresponding housing 42 make outlet hole 13 of the pot 12 and the inlet mouth 31 of the mould be aligned and touch each other, thus defining a continuous passage for the melted metal.

The alignment direction advantageously does not correspond to the axis of the arm 2, and therefore to a radial direction corresponding to the direction of the centrifugal force during the device 10 rotation.

The alignment direction is angularly offset backward with respect to the radial direction by a predetermined angle A.

Balancing means 50, joined to the end 2b of the arm 2, include a counter-weight 51, suitably adjustable on a worm screw 52, which is fastened to the end 2b of the arm 2.

The apparatus 100 includes also induction heating means 60 (Figure 2) including a coil 61.

The coil 61 is supported by a frame 62, in a housing 63 made in the bottom of the basin 1.

The coil 61 is aligned with the trajectory of the pot 12 and moves vertically between a rest position, not shown, in which the coil is wholly contained inside the housing 63, and a working position (Figure 2), in which the coil wraps the pot 12 and heats the metal contained therein until it melts.

When the metal inside the pot 12 is melted, the device 10 is driven to rotate rapidly by the arm 2 in the direction W.

During the strong initial acceleration (Figure 4), the composition of the tangential force Fa, together with the gradually increasing centrifugal force F, generates a resulting force Fr, whose direction changes in relation to the change of the angular velocity, but is substantially oriented toward the alignment direction of the outlet hole 13 and the inlet mouth 31.

Due to the shape of the cavity 15, the melted metal is pushed upwards and then toward the outlet hole 13.

Therefore, the orientation of the outlet hole 13 and of the inlet mouth 31 along a direction withdrawn with respect to the radial direction allows to use the tangential force Fa as a useful and active element of the conveying of melted metal toward the mould 30.

This allows to reduce considerably the time necessary to complete the filling operations, with respect to known filling devices, with the same initial acceleration of the apparatus 100.

The performance of the device 10 can be further easily improved by making adjustable the orientation of the mould carrier 20, for instance by hinging the mould carrier 20 to the rear prong 2c and providing means, of any known type, for adjusting the angle, in the region of the angular bracket 43.

The outlet hole 13 of the pot 12 can be oriented itself by any angle, as the pot 12 itself is placed on the plate 40.

Therefore, it is possible to choose the best alignment angle for the outlet hole 13 and the inlet mouth 31 for any type of centrifuge and metal.

The advantages of the present invention result

substantially from the possibility to exploit, in a centrifuge apparatus for melting, the tangential forces generated by the acceleration, together with the centrifugal force, to convey the melted metal toward the mould.

Another advantage of the present invention is that it proposes a device for filling moulds, which is adjustable in relation to the characteristics of the centrifuge apparatus and the metal to be treated, and therefore it allows to optimize the mould filling.

A further advantage derives from the possibility to use in best way the quantity of the melted metal in the container, thus avoiding expensive losses of material and energy.

Still another advantage of the proposed device results from its simplicity, reliability and low costs.

It is understood that what above, has been described as a pure, not limitative example, therefore, possible variants of the invention remain within the protective scope of the present technical solution, as described above and claimed hereinafter.