DESCRIPTION

The present invention relates to a mobile half-die with rapidly replaceable cavity insert, said mobile half-die being a component of die-casting dies, preferably of castings of aluminium and magnesium, and of the dies for thermoplastic injection.

In particular, the present invention relates, preferably but not exclusively, to a half-die for die casting. The sectors of the art whereto the present invention relates are, therefore, preferably but not exclusively, the automobile, truck, heating and lighting.

The dies for die casting known to the state of the art are, essentially, constituted by two main parts, a fixed one and a mobile one. Such parts are commonly known, also by the expressions fixed half-die and mobile half-die.

The fixed half-die is anchored to the moulding machine, that is, more precisely, to the injection side of the press, while the mobile half-die is configured to move away from the fixed half-die, so as to make possible the extraction and the ejection of the moulded part. The mobile half-die comprises a cavity insert, a die holder, an ejection plate and a plurality of extractors or pins. The latter are placed perpendicularly to the ejection plate and, by means of the movement of the same plate, allow the part to be ejected. The mobile half-die, usually, may comprise also a bottom plate for the connection with the die holder by means of spacers. The function of the extractors is that of pushing the moulded part outside of the cavity insert, said extractors being, in turn, pushed by the ejection plate, which, in turn, is moved by the hydraulic system that is actuated by the press. Sometimes, if it is necessary to mould parts of highly complex geometry or, in the presence of undercut areas, such as, for example, in the case of cylinder blocks, the mobile half-die comprises a plurality of side slides.

These are typically four in number, in the case of dies for cylinder blocks, or in any case in a sufficient number for eliminating all the points not in line of extraction of the part. The side slides are constituted, essentially, by sliding carriages connected to blocks which, together with the cavity insert, determine the shape of the part. The carriages are moved by one or more hydraulic cylinders, in turn connected to the press system, and are configured to translate from a first position or closure position to a second position or opening position. When the side carriages are in the first position, the die is closed and injection of the molten material can take place which has as outcome the formation of the part in the space defined by the cavity insert and by the blocks, whereas, when the side carriages are in the second position, the die is open and it is possible to extract the moulded part thanks to the action of the extractors.

The techniques currently known to the state of the art for the replacement of the cavity inserts in dies such as those described above provide for the interruption of the moulding process and the at least partial, if not complete, dismantling of the die from the entire system. In particular, in the current state of the art, the procedure of replacing a worn or malfunctioning insert in a die-casting die can only take place by means of the interruption of the moulding process, the opening of the press and the dismantling of the mobile half-die or, even, of the entire die. Since this procedure involves the suspension of the moulding process and, therefore, a halt in production that can go from eight hours to sixteen hours, the need arises to develop systems and methods that shorten the duration of the interruption of the production process and therefore allow a reduction in the resulting financial losses.

The object of the present invention is, therefore, that of providing a die, preferably for die casting, which is provided with a system that allows the rapid replacement of the cavity inserts, without it being necessary to dismantle the whole half-die, if not even the entire die. This object is achieved by the present invention, which involves the insertion in the die of a mechanical system which, exploiting the action of the hydraulic cylinder which actuates the press and determines the extraction of the moulded part, allows rapid extraction of the cavity insert, without the need to disassemble the half-die or the die.

Thanks to the mobile half-die of the present invention, if there is the need to replace the cavity insert because it is worn or, in any case, damaged, or a component thereof, the extraction of the cavity insert from the die can take place immediately after opening of the die, said opening being normally performed for the extraction of the moulded part. In this way, the time required for the replacement of the cavity insert is further reduced, because not only does the half-die or the entire die no longer have to be disassembled, but it is not necessary either for the die to be opened specifically for the extraction of the cavity insert.

One of the major difficulties encountered in replacing a worn or damaged cavity insert, as well as one of the major factors in determining the increase of the time required for the replacement of the cavity insert with the traditional techniques, is linked to the need to disassemble the system of cooling or thermal regulation of the cavity insert, in order to then extract the latter.

The dies for die casting, as well as injection dies, are, in fact, provided with a thermal regulation system for the correct control of the temperature in the cavity insert. The moulding temperature must, in fact, be comprised within a very specific range, since both too low temperatures and too high temperatures may cause problems, such as, for example, the rapid deterioration of the die in the case of too high temperatures and dimensional instability, as well as the difficult ejection of the part, in the case of too low temperatures. It is, therefore, of fundamental importance for the die and, in particular, the mobile half-die where the cavity insert is located, to be provided with a system of thermal regulation.

The latter is usually constituted by a circuit of channels in which a fluid (diathermic oil or pressurised water) is sent via an electric pump. The transmission of heat to the moulding surface takes place, therefore, by convection, between the fluid and the surface of the channels, and, by conduction, through the cavity insert material. The system of channels surrounds and penetrates the cavity insert itself, and it must be, therefore, completely dismantled if it is to be replaced.

A second object of the present invention is, therefore, to provide a die, preferably, for die casting, which is provided with a system that allows the rapid replacement of the cavity inserts, without it being necessary to disassemble the circuit of pipes that carries out the thermal regulation. This object is achieved by the present invention, which provides for the cavity insert of the die to be formed by two distinct portions, connected to each other so as to be able to be quickly and easily separated, if necessary. In particular, the cavity insert of the die will be constituted by a first portion, which is the cavity insert in the strict sense of the word and wherein the molten metal takes shape, giving rise to the moulded part, and a second portion, referred to henceforth as thermal regulation platen, which is constrained to the die holder and includes the thermal regulation circuit which controls the temperature of the first portion.

As will be better explained, in the detailed description that follows, the first portion and the second portion of the cavity insert are connected by means of a plurality of couplings with conical surface which allow the quick release of the first portion from the second portion, should it be necessary to change the first portion, that is, the portion of said cavity insert which is configured to accommodate the casting of metal from which the part takes shape. The mobile half-die of the present invention achieves, therefore, the abovementioned objects, because thanks to it, the step of extraction of the cavity insert, or rather of a first portion of the cavity insert, can be preceded by a step of release of said first portion from said second portion of said cavity insert, which remains constrained to the die holder, said second portion being apt to control the temperature of said cavity insert. These and further features will be made clearer by reading the following detailed description of some preferred embodiments of the present invention, to be considered by way of a non-limiting example of the more general concepts claimed.

In the following description reference is made to the accompanying drawings in which:

- Figure 1 is an axonometric view of a mobile half-die for die casting of the prior art, closed;

- Figure 2a is an axonometric view of a detail of a mobile half-die for die casting of the prior art, constituted by the half-die without die holder, said half-die being open and with the extractors retracted;

- Figure 2b is an axonometric view of a detail of a mobile half-die for die casting of the prior art, constituted by the half-die without die holder, said half-die being open and with the extractors in the configuration of ejection of the moulded part;

- Figure 3 is an exploded view of a mobile half-die for die casting of the prior art seen from below;

- Figure 4 is an axonometric view of a detail of a first embodiment of the present invention, constituted by the mobile half-die without die holder, said half-die being closed;

- Figure 5 is an axonometric view of a detail of a first embodiment of the present invention, constituted by the mobile half-die without die holder, said half-die being open;

Figure 6 is an axonometric view of a detail of a first embodiment of the present invention, constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place;

Figure 7 is a detail relating to the system of exchange of a first embodiment of the present invention, with mobile half-die closed;

Figure 8 is a detail relating to the system of exchange of a first embodiment of the present invention, with mobile half-die open;

Figure 9 is a detail relating to the system of exchange of a first embodiment of the present invention, with mobile half-die open and the release of said first portion from said second portion of said cavity insert having taken place;

Figure 10 is a detail relating to the system of exchange of a second embodiment of the present invention, with mobile half-die closed;

Figure 11 is a detail relating to the system of exchange of a second embodiment of the present invention, with mobile half-die open; Figure 12 is a detail relating to the system of exchange of a second embodiment of the present invention, with mobile half-die open and the release of said first portion from said second portion of said cavity insert having taken place;

Figure 13 is a detail relating to the system of exchange of a third embodiment of the present invention, with mobile half-die closed;

Figure 14 is a detail relating to the system of exchange of a third embodiment of the present invention, with mobile half-die open;

Figure 15 is a detail relating to the system of exchange of a third embodiment of the present invention, with mobile half-die open and the release of said first portion from said second portion of said cavity insert having taken place;

Figure 16a shows a section of a detail of the present invention constituted by the cavity insert in which the first portion of the cavity insert connected to the second portion of said cavity insert is visible;

Figure 16b shows a section of a detail of the present invention constituted by the cavity insert in which the first portion of the cavity insert released from the second portion of said cavity insert is visible.

Figure 17a is an axonometric view of an assembly made up of a hoist, four anchorage poles, the replacement cavity insert and a detail of the present invention constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place;

Figure 17b is an axonometric view of an assembly made up of a hoist, four anchorage poles, the replacement cavity insert and a detail of the present invention constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place and the four anchorage poles being attached to the cavity insert to be replaced:

Figure 18a is an axonometric view of an assembly made up of a hoist, four anchorage poles, the replacement cavity insert and a detail of the present invention constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place, the four anchorage poles being attached to the cavity insert to be replaced and the cavity insert to be replaced being extracted outside of the mobile half-die; Figure 18b is an axonometric view of an assembly made up of a hoist, four anchorage poles, the replacement cavity insert and a detail of the present invention, constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place, the four anchorage poles being attached to the cavity insert to be replaced and the cavity insert to be replaced being extracted outside of the mobile half-die and the hoist being rotated through 45° with respect to the bottom plate;

Figure 19a is an axonometric view of an assembly made up of a hoist, four anchorage poles, the replacement cavity insert and a detail of the present invention constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place, the four anchorage poles being attached to the cavity insert to be replaced and the cavity insert to be replaced being extracted outside of the mobile half-die and the hoist being rotated through 90° with respect to the bottom plate;

Figure 19b is an axonometric view of an assembly made up of a hoist, four anchorage poles, the replacement cavity insert and a detail of the present invention constituted by the mobile half-die without die holder, said half-die being open and the release of said first portion from said second portion of said cavity insert having taken place, the four anchorage poles being attached to the cavity insert to be replaced and the cavity insert to be replaced being extracted outside of the mobile half-die and the hoist being rotated through 135° with respect to the bottom plate;

- Figure 20 is an axonometric view of a fixed half-die whereto the mechanical system of the present invention can be attached.

Referring to Figures 1 , 2a, and 2b, a die for die casting of the prior art, for example for moulding cylinder blocks, comprises:

a fixed half-die (not shown in the drawings); and

- a mobile half-die (1 ).

The mobile half-die (1 ), comprises, in turn:

- a bottom plate (2);

- a cavity insert (3);

• - a die holder (4);

- a plurality of spacers (4\ 4");

- an ejection plate (5);

- a plurality of extractors or pins (6, 6', 6"), placed between the ejection plate (5) and the cavity insert (3); and

- four side slides (7, 7', 8, 8").

The mobile half-die (1) is able to pass from a first configuration or configuration of closure to a second configuration, or configuration of opening, and vice versa. The four side slides (7, 7', 8, 8') are configured to move, two by two, in two orthogonal directions. In particular, a first pair of side slides (7, 7') is configured to move in a first direction and a second pair (8, 8') of side slides is configured to move in a second direction orthogonal to said first direction.

The side slides (7, 7') of said first pair (7, 7') are, therefore, configured to pass from a first position of minimum distance to a second position of maximum distance. Similarly, also the side slides (8, 8') of said second pair are, therefore, configured to pass from a first position of minimum distance to a second position of maximum distance. When the mobile half-die (1 ) is in the closure configuration, the extractors (6, 6', 6") are retracted inside the die, the first pair of side slides (7, 7') and the second pair of side slides (8, 8') are in the position of minimum distance and the molten metal can fill the cavity insert (3).

Once the part has been formed in the cavity insert (3), the mobile half-die moves away from the fixed half-die and the side slides of the first pair (7, 7') move away reciprocally, passing from the position of minimum distance to the position of maximum distance, like the side slides of the second pair (8, 8'). The side slides (7, 7', 8, 8') are moved by one or more hydraulic cylinders (407, 407', 408, 408') connected directly to the system of the moulding press. After the reciprocal moving away of the side slides (7, 7', 8, 8'), it is possible to extract the moulded part. To this end, the ejection plate (5) is made to translate towards the cavity insert (3), again through the action of the press itself and in this way the extractors (6, 6', 6"), positioned between the ejection plate (5) and the cavity insert (3), push the newly moulded part, contained in the cavity insert (3), outside of the same.

Referring to Figures 1 and 3, if the cavity insert of a die of the prior art is to be replaced, it is necessary to disassemble the entire mobile half-die (1 ) from the moulding press, dismantle the bottom plate (2) by unscrewing the screws (13, 13', 13") that attach the same to the spacers (4', 4") and to the die holder (4), remove the ejection plate (5), dismantle the pipes of the cavity insert thermal regulation circuit (3) and, finally, disassemble a series of components (e.g. small plates) that lock said cavity insert (3). The time required for a procedure of this type is, usually, comprised between eight and sixteen hours.

Referring to Figures 1 , 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, a die the present invention comprises:

a fixed half-die (not shown in the drawings); and - a mobile half-die. The mobile half-die, in turn, comprises:

- a bottom plate (102);

- a cavity insert (103);

- a die holder (4);

- an ejection plate (105);

- a plurality of extractors or pins (106, 106', 106"), placed between the ejection plate (105) and the cavity insert (103);

- a plurality of side slides (107, 107', 108');

- a mechanical system (109, 109', 111 , 112, 114, 114', 115, 115", 116, 116', 117, 117', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') for the rapid extraction of the cavity insert (103); and

- four sliding shafts (118, 118', 120, 120') that is a first sliding shaft (118), a second sliding shaft (120), a third sliding shaft (118') and a fourth sliding shaft (120'), said sliding shafts (118, 118', 120, 120') being perpendicular to said bottom plate (102) and said sliding shafts (118, 118', 120, 120') being configured to connect said cavity insert (103) with said ejection plate (105) and to cooperate with said mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116 ^* , 117, 117 ^* , 119, 119', 121 , 122, 123, 123', 124, 124", 125, 125', 126, 126') for the rapid extraction of the cavity insert.

The mobile half-die can, also, comprise only two sliding shafts (118, 120) or, obviously, more than four sliding shafts.

The ejection plate (105) is configured to move from a first position, or retracted position, shown in Figures 4, 5, 7, 8, 10, 11 , 13, 14, wherein said ejection plate (105) is in contact with said bottom plate (102), or at least is located at a position of minimum distance from said bottom plate (102), to a second position, or extracted position, shown in Figures 6, 9, 12, 15, in which said ejection plate (105) is located at a position of maximum distance from said bottom plate (102).

Should the bottom plate (102) not be present, which is a component not necessary for the purpose of the functioning of the present invention, the ejection plate (105) is configured to move from a first position, or retracted position, shown in Figures 4, 5, 7, 8, 10, 11 , 13, 14, wherein said ejection plate (105) is located at a position of minimum distance from said moulding machine (401) to a second position, or extracted position, shown in Figures 6, 9, 12, 15, in which said ejection plate (105) is located at a position of maximum distance from said moulding machine (401 ).

The cavity insert(103) is configured to move from a first position or moulding position or position of minimum distance from said bottom plate (102) or from said moulding machine (401 ) to a second position or position of replacement or position of maximum distance from said bottom plate (102) or from said moulding machine (401 ).

The mobile half-die is configured to pass from a first configuration known as closure to a second configuration, or configuration of opening, and vice versa. As is the case in the dies of the prior art, when the mobile half-die is in the closure configuration, the ejection plate (105) is in its first position, the extractors (106, 106', 106") are retracted inside the die, the cavity insert (103) is in its first position or moulding position and the molten metal can fill the cavity insert (103).

Once moulding of the part has been completed, thanks to the action of the hydraulic cylinder that moves the press, the ejection plate (105) is made to translate towards the cavity insert (103), that is said ejection plate (105) passes into its second position and, while the cavity insert (103) remains in its first position or moulding position, the extractors (106, 106', 106") positioned between the ejection plate (105) _, and the cavity insert (103) push the newly moulded part, contained in the cavity insert (103), outside the same.

Referring to Figures 1 , 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, said mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') for the rapid extraction of the cavity insert (103) comprises: -four exchange plates (109, 109', 119, 119'), that is a first exchange plate (109) or first upper exchange plate (109) and a second exchange plate (109') or first lower exchange plate (109'), a third exchange plate (119) or second upper exchange plate (119) and a fourth exchange plate (119') or second lower exchange plate (119');

-a first exchange lever (111) and a second exchange lever

(121) ;

-a first exchange fork (112) and a second exchange fork

(122) , both attached to said die holder (4);

four pairs of forks (114, 114', 115, 115', 123, 123', 124, 124'), that is a first pair of forks (114, 114') or first pair of upper forks (114, 114'), a second pair of forks (115, 115') or first pair of lower forks (115, 115'), a third pair of forks (123, 123') or second pair of upper forks (123, 123') and a fourth pair of forks (124, 124') or second pair of lower forks (124, 124'); and

four pairs of connection shafts (116, 116', 117, 117', 125, 125', 126, 126') between exchange plates (109, 109', 119, 119') and forks (114, 114', 115, 115', 123, 123'. 124, 124'), that is a first pair of connection shafts (116, 116') or first pair of upper connection shafts (116, 116'), a second pair of connection shafts (117, 117') or first pair of lower connection shafts (117, 117') a third pair of connection shafts (125, 125') or second pair of upper connection shafts (125, 125'), a fourth pair of connection shafts (126, 126') or second pair of lower connection shafts (126, 126').

The components (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') of said mechanical system for the rapid extraction of the cavity insert are mounted so as to constitute two similar assemblies arranged symmetrically with respect to the cavity insert (103).

In particular, the first of said assemblies (111, 112, 109, 109', 114, 114', 115, 115', 116, 116', 117, 117') comprises: the first exchange lever .(111), the first exchange fork (112), the first upper exchange plate (109), the first lower exchange plate (109'), the first pair of upper forks (114, 114'), the first pairs of lower forks (115, 115'), the first pair of upper connection shafts (116, 116') and the first pair of lower connection shafts (117, 117').

The first exchange lever (111) is hinged to said first exchange fork (112), said first exchange fork (112) being attached to said die holder (4). The first exchange lever (111) connects, in addition, said first upper exchange plate (109) with said first lower exchange plate (109'). The first upper exchange plate (109) is connected to the first pair of upper forks (1 14, 1 14') by means of the first pair of upper connection shafts (1 16, 116') and the first lower exchange plate (109') is connected to the first pair of lower forks (1 15, 1 15') by means of the first pair of lower connection shafts (117, 1 17').

The first pair of upper forks (1 14, 1 14') and the first pair of lower forks (1 15, 1 15') are coupled to said first sliding shaft (118) and to said third sliding shaft (118 ^* ). In particular, a first fork (1 14) of said first pair of upper forks (1 14, 1 14') and a first fork (1 15) of said first pair of lower forks (1 15, 1 15') are configured to be able to pass from a first position in which they are coupled to said first sliding shaft (118) to a second position in which they are not attached to said first sliding shaft (1 18), while a second fork (114') of said first pair of upper forks (1 14, 114') and a second fork (115') of said first pair of lower forks (115, 1 15') are configured to be able to pass from a first position in which they are coupled to said second sliding shaft (1 18') to a second position in whic they are not coupled to said second sliding shaft (1 18').

Similarly, the second group (121 , 122, 1 19, 1 19', 123, 123', 124, 124', 125, 125', 126, 126') comprises: the second exchange lever (121 ), the second exchange fork (122), the second upper exchange plate (1 19), the second lower exchange plate (1 19'), the second pair of upper forks (123, 123'), the second pair of lower forks (124, 124'), the second pair of upper connection shafts (125, 125') and the second pair of lower connection shafts (126, 126').

The second exchange lever (121 ) is, therefore, hinged to said second exchange fork (122), said exchange fork (122) being attached to said die holder (4). The second exchange lever (121 ) connects, in addition, said second upper exchange plate (1 19) with said second lower exchange plate (1 19'). The second upper exchange plate (1 19) is connected to the second pair of upper forks (123, 123') by means of the second pair of upper connection shafts (125, 125') and the second lower exchange plate (1 19') is connected to the second pair of lower forks (124, 124') by means of the second pair of lower connection shafts (126, 126').

The second pair of upper forks (123, 123') and the second pair of lower forks (124, 124') are coupled to said second sliding shaft (120) and to said fourth sliding shaft (120'). In particular, a first fork (123) of said second pair of upper forks (123, 123') and a first fork (124) of said second pair of lower forks (124, 124') are configured to be able to pass from a first position in which they are hooked to said third sliding shaft (120) to a second position in which they are not hooked to said third sliding shaft (120), while a second fork (123') of said second pair of upper forks (123, 123') and a second fork (124') of said second pair of lower forks (124, 124") are configured to be able to pass from a first position in which they are hooked to said fourth sliding shaft (120') to a second position in which they are not hooked to said fourth sliding shaft (120'). The first upper exchange plate (109) and the second upper exchange plate (1 19) can move between a position of minimum distance and a position of maximum distance. Similarly, also the first lower exchange plate (109') and the second lower exchange plate (1 19') can move between a position of minimum distance and a position of maximum distance. The exchange plates (109, 109', 1 19, 1 19') and the exchange levers (11 1 , 121 ), are configured in such a way that, when the first upper exchange plate (109) and the second upper exchange plate (1 19) are in the position of maximum distance, the first lower exchange plate (109') and the second lower exchange plate (1 19') are in the position of minimum distance and, vice versa, when the first (109) and the second (1 19) upper exchange plates are in the position of minimum distance, the first (109') and the second (1 19') lower exchange plates are in the position of maximum distance.

It is obvious that, in the case wherein the mobile half-die comprises only two sliding shafts (1 18, 120), said mechanical system comprises, instead of four pairs of forks (114, 1 14', 1 15, 1 15', 123, 123', 124, 124'), only four forks, namely a first upper fork (1 14), a first lower fork (115), a second upper fork (123) and a second lower fork (124). Consequently, said mechanical system comprises only four connection shafts (116, 117, 125, 126), instead of four pairs of connection shafts (116, 116', 117, 117', 125, 125', 126, 126'). The mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') can take on three different positions or configurations. More particularly the mechanical system (109, 109',

111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') can be in a first position wherein said mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121,

122, 123, 123', 124, 124', 125, 125', 126, 126') is configured in such a way as to prevent the movement of the cavity insert (103), said cavity insert (103) being in the moulding position; in a second position wherein said mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122,

123, 123', 124, 124', 125, 125', 126, 126') is configured in such a way as to make possible the movement of the cavity insert (103) from the moulding position to the replacement position; and, finally, in a third position wherein said mechanical system (109, 109', 111,

112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118", 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') is configured so as to prevent the movement of the cavity insert (103), said cavity insert (103) being in the replacement position, and said ejection plate (105) being locked in the position of maximum distance from the moulding machine (401).

The mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124 ^* .125, 125', 126, 126') is, therefore, configured to move from said first position to said second position, and vice versa, as well as from said second position to said third position and vice versa.

In greater detail, when the mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') is in its first position, as shown in Figures 4, 7, 10 and 13, the following situation occurs:

the first (114, 114') and the second (123, 123') pair of upper forks are in their first position, that is, they are hooked to said sliding shafts (118, 118', 120, 120'); the first (115, 115') and the second (124, 124') pair of lower forks are in their second position, that is they are not hooked to said sliding shafts (118, 118', 120, 120');

the first upper exchange plate (109) and the second upper exchange plate (119) are at a position of minimum distance, and the first lower exchange plate (109') and the second lower exchange plate (119') are, consequently, at a position of maximum distance.

The cavity insert (103) remains therefore locked in its moulding position thanks to the upper forks (114, 114', 123, 123') which lock the sliding shafts (118, 118', 120, 120').When the mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') is in its second position, as shown in Figures 5, 8, 11 and 14, the following situation occurs:

the first (114, 114') and the second (123, 123') pair of upper forks are in their second position, that is, they are not hooked to said sliding shafts (118, 118', 120, 120');

the first (115, 115') and the second (124, 124') pair of lower forks are in their first position, that is, they are hooked to said sliding shafts (118, 118', 120, 120'); the first upper exchange plate (109) and the second upper exchange plate (119) are at a position of maximum distance and the first lower exchange plate (109') and the second lower exchange plate (119') are, consequently, at a position of minimum distance.

The cavity insert (103) is, therefore, free to translate from the moulding position to the replacement position, thanks to the translation of the ejection plate (105) from its retracted position to its extracted position.

When the mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') is in its third position, as shown in Figures 6, 9, 12 and 15, the following situation occurs:

the first (1 14, 1 14') and the second (123, 123') pair of upper forks are in their second position, that is, they are not hooked to said sliding shafts (1 18, 1 18', 120, 120');

the first (1 15, 115') and the second (124, 124') pair of lower forks are in their first position, that is, they are hooked to said sliding shafts (1 18, 1 18', 120, 120'); the first upper exchange plate (109) and the second upper exchange plate (1 19) are at a position of maximum distance and the first lower exchange plate (109') and the second lower exchange plate (1 19') are, consequently, at a position of minimum distance;

said lower forks (1 15, 1 15', 124, 124') are disconnected from said lower connection shafts (1 17, 1 17', 126, 126').

The ejection plate (105) remains locked in its second position, or extracted position, or end of stroke position, thanks to the upper forks (1 14, 1 14', 123, 123') that prevent the further moving away of the ejection plate (105) from the bottom plate (102) or from the moulding machine (401 ), fixing a maximum distance between the ejection plate (105) and the bottom plate (102) or between the ejection plate (105) and the moulding machine (401 ). When the ejection plate (105) is in its end of stroke position, the cavity insert (103) remains, consequently, locked in the replacement position.

Referring to Figures 1 , 16a and 16b, the cavity insert (103) of the die is constituted by a first portion (103') and a second portion (103').

Said first portion (103') is that part of the cavity insert (103) in which the molten metal takes shape, giving rise to the moulded part. Said second portion (103'), referred to hereinafter as thermal regulation platen (103'), comprises the thermal regulation circuit which controls the temperature of the first portion (103'). Said thermal regulation platen (103") is restrained to the die holder (4) and is connected to said first portion (103') by means of at least one conical surface coupling (127), i.e. a coupling formed by two truncated cone surfaces which engage one in the other. Preferably, said thermal regulation platen (103") is connected to said first portion (103') by means of a plurality of couplings (127, 127', 127").

Referring to Figures 1 , 6, 16a and 16b, when the mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') is in its third position and, therefore, the cavity insert (103) is in its second position, the first portion (103') of said cavity insert (103), is unhooked from the thermal regulation platen (103") which, instead, remains restrained to the die holder (4).

The mechanical system (109, 109', 111 , 112, 114, 114 ^* , 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') can be moved in different ways including, here below, some of which mentioned by way of a non-exclusive example of possible other equivalent embodiment solutions.

Referring to Figures 4, 5, 6, 7, 8, 9, in a first embodiment of the present invention, the passage of the mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') from the first to the second position takes place by exploiting the side slides (107, 107', 108') which, thanks to the action of the hydraulic cylinders with which they are provided, pass from their position of minimum distance to their position of maximum distance, when the half-die passes from its position of closure to its position of opening. To this end, the mobile half-die comprises two levers (128, 128') which connect said side slides (107, 107') with said mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 1 18', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126'). In particular, the mobile half-die comprises a first lever (128) which connects a first side slide (107) with the first upper exchange plate (109) and a second lever (128') which connects a second side slide (107') to the second upper exchange plate (119). Said levers (128, 128') are configured so that when said side slides (107, 107') pass from their position of minimum distance to their position of maximum distance, said levers (128, 128') move integrally with said side slides (107, 107') and make said first upper exchange plate (109) and said second upper exchange plate (119) pass from their position of minimum distance to their position of maximum distance, said first lower exchange plate (109') and said second lower exchange plate (119') move from their position of maximum distance to their position of minimum distance and, therefore, the mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') pass from its first position to its second position.

Referring to Figures 10, 11 and 12, in a second embodiment of the present invention, the passage of the mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') from the first to the second position takes place thanks to the action of two dedicated hydraulic cylinders (129, 129'). In particular, a first (129) of said two hydraulic cylinders (129, 129') moves the group formed by the first upper exchange plate (109), the first lower exchange plate (109') and the first exchange lever (111 ). The second (129') of said two hydraulic cylinders (129, 129') moves the assembly formed by the second upper exchange plate (119), the second lower exchange plate (119') and the second exchange lever (121).

Said two hydraulic cylinders (129, 129') are, therefore, configured in such a way as to cause the passage of said first upper exchange plate (109) and said second upper exchange plate (119) from their position of minimum distance to their position of maximum distance and, therefore, the passage of the lower exchange plates (109', 119') from their position of maximum distance to their position of minimum distance.

Said two hydraulic cylinders (129, 129') are, therefore, configured in such a way as to cause the passage of said mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') from its first position to its second position.

Referring to Figures 13, 14 and 15, in a third embodiment of the present invention, the passage of the mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') from the first to the second position takes place manually.

To this end, the exchange plates (109, 109', 119, 119') are provided with a hole (130, 130', 131, 131') configured so as to receive in its interior a screw (132, 133) for the locking of said plates (109, 109', 119, 119'). In particular, the third embodiment of the present invention provides for the use of two screws: a first screw (132) used to lock, alternately, the first upper exchange plate (109) and the first lower exchange plate (109' ); and a second screw (133) used to lock, alternately, the second upper exchange plate (119) and the second lower exchange plate (119').

Therefore, when the mechanical system (109, 109', 111, 112, 114, 114', 115, 115", 116, 116', 117, 117', 118, 118", 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') is located in its first position the first screw (132) and the second screw (133) respectively lock the first upper exchange plate (109) and the second upper exchange plate (119). When, instead, the mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') is located in its second position and third position the first screw (132) and the second screw (133) respectively lock the first lower exchange plate (109') and the second lower exchange plate (119'). If the mechanical system (109, 109', 111, 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121, 122, 123, 123', 124, 124', 125, 125', 126, 126') is to be passed from its first to its second position, the first and the second screws have to be unscrewed, manually, from the holes of the upper exchange plates (109, 119), the exchange plates have to be moved so that the upper exchange plates (109, 19) pass from their position of minimum distance to their position of maximum distance and the lower exchange plates (109', 1 19') pass, consequently, from their position of maximum distance to their position of minimum distance, and finally the screws have to be screwed in said lower exchange plates (109', 1 19'), so that said first screw (132) locks the first lower exchange plate (109) and the second screw (133) locks the second upper exchange plate (1 19).

Referring to Figures 17a, 17b, 17c, 18a, 18b, 18c, 19a, 19b, 19c, the replacement of the cavity insert (103), after the procedure of extraction of the same has taken place according to what is described above, takes place in the following way:

the new cavity insert (140) is hooked by a hoist (141 ) whereto a plurality of poles (142, 142', 142") are connected, said poles (142, 142', 142") being configured in order to connect said hoist (141 ) with the cavity insert to be replaced (103);

said hoist (141 ) is brought close to the cavity insert to be replaced (103) in such a way that said plurality of poles (142, 142', 142") is in a useful position in order to be able to hook said cavity insert to be replaced (103); hooking of the cavity insert to be replaced (103) to said plurality of poles (142, 142', 142");

moving of the hoist (141 ) in the median point of joining of the new cavity insert (140) and of the cavity insert to be replaced (103) or in any case in such a way as to balance the weight of the cavity insert to be replaced (103) and of the new cavity insert (140);

optionally, moving of the hoist (141) backwards to a sufficient extent in order not to have a collision during the subsequent rotation;

rotating of the hoist (141 ) through 180° so as to have the new cavity insert (140) in a useful position for the insertion of the same in the housing (145) previously occupied by the cavity insert to be replaced (103); insertion of the new cavity insert (140) in said housing (145);

hooking of said plurality of poles (142, 142', 142") by the cavity insert to be replaced (103);

moving away of the hoist (141 ).

At this point, with a reverse sequence with respect to what is described above in relation to the extraction of the cavity insert to be replaced (103), said mechanical system (109, 109', 111 , 112, 114, 114', 115, 115', 116, 116', 117, 117', 118, 118', 119, 119', 121 , 122, 123, 123', 124, 124', 125, 125', 126, 126') passes from its third position to its second position and from its second position to its first position. The new cavity insert (140) is in this way returned inside the half-die which can, in this way, be closed once again, in order to start a new moulding cycle.

Referring to Figure 20, it is obvious that the mechanical system described hitherto can also be mounted on a fixed half-die (501).

There are, in fact, some particular moulding machines for die casting where the moulded part is extracted from the fixed half-die. In these cases it is possible to use the same mechanical system described for the mobile half-dies and the same division of the cavity insert (504) into a first portion wherein the molten metal takes shape and a second portion which is connected to said first portion by means of at least one conical surface coupling and comprises the thermal regulation circuit which controls the temperature of the first portion. In this way the extraction of the cavity insert from the fixed half-die can take place immediately after opening of the die, said opening being normally performed for the extraction of the moulded part.

In the case of fixed half-dies, the movement of the mechanical system takes place through the action of the press itself, since in this case the mechanical system, being on the fixed half-die, is directly connected to the moulding machine and, therefore, to the systems of movement of the latter.

Thanks to the half-die, described hitherto, the objects proposed are achieved and the disadvantages suffered in the prior art overcome. In particular, thanks to the mechanical system of extraction of the cavity insert and to the introduction of a thermal regulation platen reversibly restrained to the rest of the cavity insert, the extraction of the cavity insert from the die can be concurrent with the opening of the die for the extraction of the moulded part. In this way the time necessary for the replacement of the cavity insert, or of its components, is strongly reduced, passing from approximately 8-16 hours to approximately one hour, in the case of the mobile half-die and, from 4-5 hours to approximately 5 minutes, in the case of the fixed half-die.