Background Art As is known, for die-casting of items made of aluminum, aluminum alloys, light alloys and the like, a casting technique is used which is known as low-pressure casting, wherein the liquid metal is made to rise from the furnace through a duct for introducing the liquid metal that exits upward in a die formed by two or more parts.

Once the filling of the die has been completed, the liquid metal must solidify, and this occurs normally over a relatively long time, furthermore forming a relatively large sprue at the liquid metal input channel.

This type of casting has the drawback of having long casting times in addition to a waste of material determined by the sprue and to the fact that the cast item has a structure that is relatively scarcely compacted, since casting occurs at low pressure.

According to what is disclosed in document WO 02/089625 by the same Applicant, assumed incorporated herein by reference, a casting technique is described which allows to produce items, particularly shoe toe caps, with a particularly compact structure that arises from the fact that the two parts of the die that form the impression of the cast item are mutually closed with a pressing action, thus achieving compaction of the material and considerable structural uniformity, furthermore avoiding the formation of sprue, with the consequent benefits regarding the casting time.

In this solution it was necessary to provide a relatively precise dosage of the liquid metal and it was therefore necessary to have a dosage device that allowed to introduce dosed quantities of material.

Although this solution is valid in-many respects, it was relatively

complicated from a constructive standpoint.

Disclosure of the Invention The aim of the invention is indeed to solve the above problems, providing an apparatus for manufacturing items made of aluminum, aluminum alloys, light alloys and the like, which allows to cast items that have a very compact structure without however having to use a dosage device to introduce the liquid metal, which is instead in practice dosed automatically by the apparatus.

Within this aim, an object of the invention is to provide an apparatus that allows to produce items without sprue and with considerably shorter times for obtaining the solidification step.

Another object of the present invention is to provide an apparatus that allows to provide, with a single casting operation, a plurality of parts that may optionally be different one another, obtaining correct dosage for each cast part.

Another object of the present invention is to provide an apparatus that by virtue of its particular constructive characteristics is capable of giving the greatest assurances of reliability and safety in use.

Another object of the present invention is to provide an apparatus that can be obtained easily starting from commonly commercially available elements and materials and is also competitive from a merely economical standpoint.

This aim and these and other objects that will become better apparent hereinafter are achieved by an apparatus for manufacturing items made of aluminum, aluminum alloys, light alloys and the like, comprising, on a platen, a lower die and at least one upper die, a duct for introducing liquid metal that is connected to a furnace, said liquid metal input duct arriving from below and leading into said lower die, characterized in that said lower die forms at least one lower impression, which has at least one concave portion for introducing a dosed quantity of liquid metal, a male plug being associated with said upper die, said male plug being adapted to move with

respect to said upper die and forming at least one upper impression that can be coupled to said at least one lower impression in order to determine the shape of the item being cast, said at least one upper die being closable onto said lower die and said male plug closing said shape and acting as a flow control element for the port that provides a connection to said input duct.

Brief description of the Drawings Further characteristics and advantages will become better apparent from the detailed description of an apparatus for manufacturing items made of aluminum, aluminum alloys, light alloys and the like, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a schematic sectional view of the apparatus, taken along a vertical plane, during the initial step of casting; Figure 2 is a view illustrating the step for introducing the liquid metal in the lower die; Figure 3 is a view illustrating the step for dosing the liquid metal; Figure 4 is a view illustrating the step for the closure of the upper die onto the lower die; Figure 5 is a schematic plan view of a die with three impressions; Figure 6 is a schematic view of a safety shoe toe cap that can be obtained with the apparatus according to the invention.

Ways of carrying out the Invention With reference to the figures, the apparatus for manufacturing items made of aluminum, aluminum alloys, light alloys and the like, according to the invention, comprises a platen, generally designated by the reference numeral 1, on which there is a lower die 2 with which an upper die 3 cooperates; said upper die can perform a translational motion toward and away from the lower die.

There is also a duct 10 for introducing liquid metal, which arrives from below from a furnace 11 of the liquid metal which is preferably of the pressurized type; the duct 10 runs through the platen, where there are usual

heating means 12, until it exits at the impressions 20 provided in the lower die.

In the illustrated specific example there are three lower impressions that are uniformly distributed circumferentially around the input duct 10 and are connected thereto by way of ports 22 that form in practice, as explained hereinafter, ports for the overflow of the liquid metal.

The lower impression 20 has at least one concave portion 23 that allows to introduce therein a quantity of liquid metal that is a direct function of the geometry of the concave portion; therefore, by introducing the liquid metal and making it rise through the duct, by virtue of a pressing action applied by the furnace, it is possible to fill the concave regions or portions 23 with a quantity of liquid metal that in practice is dosed.

It is possible to provide level sensors 30 to stop the rise of the liquid metal or it is optionally possible to preset the time and the pressure applied to the liquid metal so as to achieve dosed overflow of said liquid metal.

Once the concave regions have been filled, the level of the liquid metal is lowered again (Figure 3), so as to provide precise dosage of the metal according to the position of the overflow ports 22 that form the region for the overflow of the liquid metal into the concave regions 23.

At least one male plug 8 is connected to the upper die 3, can move with respect to the upper die 3, and forms an upper impression 25, which in cooperation with the corresponding lower impression 20 forms the shape of the item being cast. The specific example illustrates a toe cap 21 for safety shoes.

An important particularity of the invention consist in that after closing the upper die 3 onto the lower die 2 and after dosing the liquid metal, the piston 8, which moves with respect to the upper die 3, closes the port 24 for connection to the liquid metal input duct 10, thus achieving clear separation with respect to the column of'liquid metal, which moreover, to perform dosage, had been made to descend in the channel 10, so as to place the free

surface of the liquid preferably at the heated region.

The movement of the male plug 8 with respect to the upper die 3 applies pressure to the liquid metal, producing a particular compaction of said metal and thus obtaining parts that have considerable structural uniformity and improved mechanical strength.

It is also noted that the particular solution adopted, in which the dosage of the metal is substantially produced by the shape of the lower impression and more particularly by the concave portion of the lower portion, allows to arrange around the same input channel impressions that are different one another and in which the liquid metal is always dosed correctly, said dosage being possibly different in each impression.

It should be noted that with the arrangement described above it is possible to introduce in the various impressions a dosed quantity of liquid metal without having to resort to particular operations but simply by making the liquid metal that arrives from the input duct overflow and by bringing said liquid metal to a presettable limit that can be determined directly by a level sensor 30, as shown, or optionally by using the time for which pressure is applied to the liquid metal, said pressure causing its rise and consequently its introduction in the various recesses.

It is evident from what has been described above that the invention achieves the intended aim and objects, and in particular the fact is stressed that the male plug in practice forms a flow control element that closes the port for connection to the liquid metal input duct, avoiding the formation of sprue and also generating pressure on the liquid metal undergoing solidification, which helps to obtain a product with high-level structural and mechanical characteristics.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

All the details may further be replaced with other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to requirements.

The disclosures in Italian Patent Application No. MI2002A000223 from which this application claims priority are incorporated herein by reference.