EP3423215B1 - Diecasting die system - Google Patents

Description

The present invention relates to a die-casting method and a die-casting nozzle system for use in a hot-chamber system for die-casting molten metal, comprising a hot-chamber die-casting machine with a pouring vessel and a melt distributor which distributes the melt evenly from a machine nozzle to evenly heated die-casting nozzles. At least one non-return valve is arranged between a sprue area of the die-casting nozzle and the casting container, the non-return valve preventing the backflow of the melt away from the sprue area in the direction of the casting container.

The sprue as a by-product of casting, which solidifies in the channels between the die-casting nozzle and the casting mold in conventional die-casting processes and ultimately joins the cast parts together after demoulding in an undesirable manner, entails additional material expenditure, which usually accounts for between 40% and 100% of the weight of the casting. Even if the sprue is melted down again for material recycling, this is associated with energy and quality losses due to the slag and oxide components that are produced. Sprueless die casting avoids these disadvantages.

For sprueless die casting, it is necessary to either bring the melt in the liquid state from the crucible to the mold for each casting and then return it again, which also leads to a loss of quality, or at least to loss of time, or the melt in the liquid state at the sprue to keep the shape. The latter happens in the hot chamber process, where all channels up to the sprue are heated in such a way that the melt remains liquid and, ideally, is prevented from flowing back to the crucible.

Backflow into the crucible can be prevented by valves, but also in a particularly advantageous manner by a plug of solidified melt which closes the sprue opening in the die-casting nozzle.

Nozzle systems with melt distributors, heated nozzles and closing devices are known from the prior art. However, these work with actively controlled valve elements, as in the publications DE 103 54 456 A1 , DE 103 59 692 A1 and U.S. 2003/209532 A1 is described. Alternatively, a plug formation is used, for example from the references U.S. 2007/181281 A1 and U.S. 2007/221352 A1 known. Closure devices between the last branch of the melt manifold and the gate area of the nozzles are off the pamphlet U.S. 2003/209532 A1 , where an actively controlled valve element is provided, as well as from the references U.S. 2007/181281 A1 and U.S. 2007/221352 A1 known. The use of non-return valves is also known in hot chamber systems of hot chamber die casting machines, for example from the publication DE 198 07568A1 , where the non-return valve is arranged as usual around the pump area (piston, piston housing) and thus far in front of any melt distributor.

Although conventional valves prevent the melt from flowing back into the crucible, in multiple systems they are unsuitable for preventing higher-lying strands from leaking into lower-lying strands and from escaping from the die-casting nozzle. Although this is prevented by sealing with a plug of solidified melt, it is complicated to achieve short cycle times for high dynamics with this method because of the necessary rapid change between melting and solidification.

This problem results in the task of offering a die-casting nozzle system for use in a die-casting hot-chamber system for molten metal, which allows simple temperature control and a simple structure.

The object is achieved by a die-casting nozzle system for use in a hot-chamber system for die-casting molten metal, in the hot-chamber process in which the melt is held in liquid state at a sprue of a mold, the hot-chamber system comprising a hot-chamber die-casting machine with a casting container and a machine nozzle, via which the melt enters the die-casting nozzle system, the die-casting nozzle system comprising at least one upper and at least one lower die-casting nozzle, each with a sprue area, and a melt distributor, which distributes the melt evenly from the machine nozzle to the die-casting nozzles, with at least one check valve between the sprue area of the die-casting nozzles and the pouring container, wherein the non-return valve prevents the backflow of the melt away from the sprue area in the direction of the pouring container. Primarily low-viscosity melts, especially of non-ferrous metals, are intended here, up to the melting point of aluminum. According to the prior art, however, the liquid melt from an upper nozzle are pulled back and at the same time leak out of a lower nozzle in an undesired manner due to the shearing force.

According to the invention, it is provided to solve this problem that the non-return valve is arranged between the sprue area of at least the at least one upper die-casting nozzle and a last branch of melt channels in the melt distributor of the hot chamber system to each of the die-casting nozzles, in particular to the at least one upper die-casting nozzle. This prevents melt from escaping from the die-casting nozzles at all times if no melt shoots in via the melt distributor, which would lead to contamination and danger, especially when the mold is open. The risk of melt escaping results from the fact that the melt channels in the melt distributor form communicating tubes and as a result melt flows back from a die-casting nozzle arranged in the upper area of the melt distributor and accordingly melt flows out of a die-casting nozzle arranged in the lower area of the melt distributor due to the effect of gravity could. However, this is prevented by the non-return valve in the area between the sprue area of the die-casting nozzle and the last branch in the melt distributor, at least to the die-casting nozzle, for example in the upper die-casting nozzle itself.

An advantageous embodiment provides that the die-casting nozzles can be heated from the inside and/or from the outside in the area of a nozzle body and include sprue areas that have at least the thermal conductivity of the melt to be processed itself and/or can be heated separately. It is particularly advantageous if the heating takes place from the outside and the heat is passed on to the sprue areas, so that there is no need for internal heating. Provision is therefore made for the die-casting nozzle to be externally heated, with the external heating also being able to be designed as a printed heating (thick film heating). The external heater can be formed by a heat-shrinkable brass or stainless steel sleeve containing the heater.

Due to the low heat dissipation from the sprue area, the die-casting nozzle can thus be heated indirectly, in that the heat from the heated nozzle body flows over into the sprue area. The highest possible thermal conductivity, but not lower than that of the melt itself (e.g. Zn > 100 W/mK, Mg around > 60, Al around 235 W/mK) is achieved through suitable material selection, for example a molybdenum alloy, tungsten or a thermally conductive ceramics. Alternatively or additionally, the die-casting nozzle is internally heated, which is also covered by the invention.

Also advantageous is a thermal protection device provided in the sprue area of each die-casting nozzle, which reduces heat dissipation from the sprue area in the direction of the casting mold. Thermal insulation in the sprue area is particularly suitable for this. Thermal insulation can be used for this purpose, which can be used as an insulating ring made of a material with low thermal conductivity surrounding the sprue area, such as e.g. titanium alloys or ceramics, as an insulating layer of air, gas or vacuum within the gate area and/or as a constant layer of air between the body of the die and the mold forming a uniform or circumferential air gap as an insulating space. The insulation serves to prevent heat loss and minimize the heating output.

The sprue area of the mold preferably has insulation that reduces the outflow of heat into the mold. The insulation is part of the nozzle and is not formed by the mold or the melt as is the case with plastic injection molding. In addition, it is also provided as an alternative or in addition to thermal insulation, the To heat the sprue area of the mold, so to speak as an "active insulation" to reduce the heat dissipation from the sprue area through these measures. As a result, the melt remains liquid in the sprue area and does not have to be melted again after the cast part has been torn off. This leads to simple heating of the nozzle, despite all the advantages of holding the melt in the nozzle. For this purpose, it is also provided to produce the nozzle front from insulating material.

Alternatively, a further embodiment of counter-heating is provided in order to reduce the heat dissipation. This counter-heating is preferably designed as a separately heatable segment arranged around the sprue and/or as a separately heatable sprue area. Counter-heating that uses a highly dynamic CO ₂ cycle process for its operation has proven to be particularly advantageous.

A melt channel, which has a tear-off edge in the area of the sprue area of the die-casting nozzle that is designed in such a way that it forms a cross-section-reducing predetermined breaking point in the melt that has solidified in the sprue area, ensures high product quality . The tear-off edge is arranged on one side either circumferentially on the outside of a central conductor or on the inside of the melt conductor, in each case at the lower end lying towards the sprue area. A two-sided arrangement is also provided.

Furthermore, it has proven advantageous if a temperature sensor is arranged in the sprue area. This temperature sensor produces readings that can be used to control the nozzle heater. Controlled nozzle heating enables optimal process control, increases productivity and product quality and reduces wear on the die-casting nozzle. The temperature sensor in the front area of the nozzle, the area close to the sprue, thus supports optimized operation of the heater by using its measured values to control the nozzle heater.

It has proven to be particularly advantageous if the check valve is arranged in the nozzle channel of the die-casting nozzle itself. A suitable non-return valve has a freely movable ball, preferably in a cage, which interacts with a valve seat.

It is favorable if the nozzle has a specific sprue geometry. A ring ensures a clean demolition, cross or star shapes are also provided. If the central conductor forming the ring is given a longitudinal bore that leads through the sprue area. This enables a better flow of the melt with just as good tear-off. The quality of the tear-off is further improved by a tear-off edge, which can be arranged inside and/or outside in the sprue area. The die-casting nozzle thus advantageously has a sprue geometry that is adapted to the respective requirements.

The gate cools only when the heat flows into the casting, the product, and cools the gate area as long as the casting remains bonded to the gate area. However, the sprue area does not cool down too much because, due to thermal insulation in the sprue area of the nozzle, only little heat flows directly into the mould. As a result, the heat flow is channeled essentially via the liquid or solidified melt.

• Aufsetzen der permanent und gleichmäßig beheizten Druckgussdüse auf die Gießform;
• Öffnen des Rückschlagventils beim Einschießen der Schmelze durch den Schmelzekanal und den Angussbereich bis in die Gießform;
• Erstarren der Schmelze zu einem Erzeugnis in der Gießform bis in den Angussbereich hinein, wobei Wärme aus dem Angussbereich in das Erzeugnis strömt;
• Abheben der Druckgussdüse, Abriss des Erzeugnisses und ausbleibender Abfluss der Wärme aus dem Angussbereich;
• Aufschmelzen der erstarrten Schmelze in dem Angussbereich aller Druckgussdüsen durch aus dem Düsenkörper nachströmende Wärme, wobei ein Ausfließen der Schmelze aus dem unteren Düsen im Verteiler, die aus den oberen Düsen über den Verteiler strömt, verhindert wird, indem die Rückschlagventile im Bereich der oberen Düsen schließen.

According to the invention is also a die-casting method using a die-casting nozzle system as described above. The die casting process includes the following process steps:

• Placing the permanently and evenly heated die-casting nozzle on the casting mold;
• Opening of the non-return valve when injecting the melt through the melt channel and the sprue area into the casting mold;
• solidifying the melt into a product in the mold up to the sprue area with heat flowing from the sprue area into the product;
• Lifting of the die casting nozzle, tearing of the product and failure to dissipate the heat from the sprue area;
• Melting of the solidified melt in the sprue area of all die-casting nozzles by heat flowing from the nozzle body, whereby the melt from the lower nozzle in the distributor, which flows from the upper nozzles via the distributor, is prevented from flowing out by closing the non-return valves in the area of the upper nozzles .

Such a method does not require the formation of a sealing melt slug in the sprue area, so that the cycle frequency during die-casting can be increased and the alternating thermal stress on the die-casting nozzle can be reduced. In addition, security against escaping melt is increased.

An advantageous embodiment of the method provides that the die-casting nozzle can be heated from the inside and/or from the outside in the area of a body of the die-casting nozzle and includes the sprue area, the material of which has a thermal conductivity of at least the thermal conductivity of the melt itself and/or can be heated separately.

• Fig. 1: in schematischer Darstellung ein erfindungsgemäßes Druckgussdüsensystem;
• Fig. 2: in schematischer Schnittdarstellung ein erfindungsgemäßes Druckgussdüsensystem mit zwei Druckgussdüsen;
• Fig. 3: eine weitere Ausführungsform der Druckgussdüse;
• Fig. 4: eine Ausführungsform eines Details der erfindungsgemäßen Druckgussdüse im Angussbereich;
• Fig. 5: eine weitere Ausführungsform des erfindungsgemäßen Druckgussdüsensystems;
• Fig. 6: eine weitere Ausführungsform des erfindungsgemäßen Druckgussdüsensystems;
• Fig. 7: eine weitere Ausführungsform der erfindungsgemäßen Druckgussdüse und
• Fig. 8: mehrere unterschiedliche Angussgeometrien.

Further details, features and advantages of the invention result from the following description of exemplary embodiments with reference to the associated drawings. Show it:

• 1 : a schematic representation of a die casting nozzle system according to the invention;
• 2 : a schematic sectional view of a die-casting nozzle system according to the invention with two die-casting nozzles;
• 3 : another embodiment of the die casting nozzle;
• 4 : an embodiment of a detail of the die-casting nozzle according to the invention in the gate area;
• figure 5 : another embodiment of the die casting nozzle system according to the invention;
• 6 : another embodiment of the die casting nozzle system according to the invention;
• 7 : another embodiment of the die-casting nozzle according to the invention and
• 8 : several different gate geometries.

1 shows a schematic representation of a hot chamber system 1, comprising an embodiment of a die-casting nozzle system 10 according to the invention, connected to a well-known hot-chamber die-casting machine 2. This is moved downwards by a piston 5, driven by a piston drive 6, so that the melt 4 reaches the die-casting nozzle system 10 via a machine nozzle 7.

In the die-casting nozzle system 10, the melt 4 is first pressed into the melt distributor 20, which distributes the melt 4 to the individual die-casting nozzles 40. The die casting nozzles 40 are directly connected to the fixed mold half 32 as part of the casting mold 30 . Between the fixed mold half 32 and a Movable mold half 34 is a cavity 36 in which the product is formed after the injection of the melt 4 and its solidification.

2 shows a schematic sectional view of an embodiment of a die-casting nozzle system 10 according to the invention with two die-casting nozzles 40, one upper and one lower. The die casting nozzles 40 are inserted into the fixed mold half 32 of the casting mold 30 and connected to the melt distributor 20 . Two radial seats 24 and an axial seat 26, on which the die casting nozzle 40 is supported, secure its position within the casting mold 30. The sealing function of the front radial seat 24 can also be improved by an additional sealing element, not shown here. The function of this space becomes 3 described in more detail.

If the die-casting nozzle system 10 is in operation, the machine nozzle is located on a machine nozzle extension 12 and is attached to the melt distributor 20 under mechanical pressure and is thus tightly connected. As a result, the melt can get from the casting container into a melt channel 22 of the melt distributor 20 and to the die-casting nozzles 40 in their respective nozzle channel 41 . The melt flows from the nozzle channel 41 through the check valve 48, which opens in the direction of flow, to the sprue region 42, where it shoots into the cavity 36. There, after the melt has solidified, the product is formed in the cavity. In addition, the melt can also solidify in the sprue area 42 since the heat of the melt is dissipated via the (often additionally cooled) casting mold 30 .

In a particularly advantageous embodiment, the check valve is designed as a ball valve and in such a way that the ball is light in weight and has a short stroke, for example one millimeter. This property ensures high dynamics in the function of the die-casting nozzle according to the invention.

In order to be able to remove the finished product, the movable mold half 34 is lifted off. In the process, the product tears off the sprue area 42 of the die-casting nozzle 40 . With the demolition of the product and the removal of the movable mold half 34, there is no flow of heat into the casting mold 30. The heat generated by a nozzle heater 43 and given off to the die-casting nozzle 40 then heats the sprue area 42 to such an extent that the in the sprue area 42 solidified melt melts again. The nozzle heater 43 is designed here as a sleeve, for example made of brass or stainless steel, which contains the heater and which is pushed onto the body of the die-cast nozzle 40 .

The sprue area in the die-casting nozzles 40 is thus open again for the melt to exit. As long as there is only one die-casting nozzle 40, the melt would be prevented from exiting by capillary forces or a lack of pressure equalization. However, as soon as a plurality of die-casting nozzles are present, above all arranged one above the other, air can enter the upper die-casting nozzle 40 through the sprue area 42 . The incoming air then leads to pressure equalization in the melt channel 22 of the melt distributor 20, so that the melt flows back from the upper die-casting nozzle 40 to the melt channel 22 from the lower die-casting nozzle 40 in an undesired manner. a. can escape when the mold 30 is open. Of course, this also applies if the melt does not solidify in the sprue area, but remains free-flowing.

In order to prevent melt from flowing out, the non-return valve 48 is provided according to the invention, which prevents the melt from flowing back to the melt channel 22 of the melt distributor 20 . As a result, due to a lack of pressure equalization, no melt can escape from the lower die-casting nozzle 40 either. The sprue area 42 also of the lower nozzle in each case remains as a result even without an additional measure for closure, such as e.g. B. a solidified melt plug or a nozzle needle, practically tight.

3 shows a schematic sectional view of an embodiment of the die-casting nozzle 40 of the die-casting nozzle system 10 according to the invention, including a detailed view of the sprue area 42. The die-casting nozzle 40 is connected to the melt distributor 20, so that there is a connection between its melt channel 22 and the nozzle channel 41. The non-return valve 48 is also advantageously arranged in the nozzle channel 41, shown here schematically. However, it could also be arranged at any desired position in the section of the melt channel 22 shown.

Furthermore, the nozzle heater 43 is shown and (only in the detailed representation) a part of the fixed mold half 32 on which the die casting nozzle 40 is supported. A thermal insulation provided. In the example shown, this consists of an air space 58 which surrounds a substantial part of the die-casting nozzle 40 and, above all, of a sprue insulation 50 . The sprue insulation 50 is arranged directly in the sprue region 42 . It consists of a cavity filled with air, another gas, or an insulating material. In addition, it is provided that the sprue area is made from a different material that has reduced thermal conductivity, for example from a ceramic. The sprue insulation 50 can be achieved by the form-locking or material-locking joining together of correspondingly designed parts that delimit the cavity.

The sprue insulation 50 is particularly effective in preventing a large part of the heat dissipation via the radial seat 24. This makes it possible to heat the sprue area 42 and melt the melt that has solidified there via the existing nozzle heater 43, without having to arrange an additional heater in the sprue area 42. However, such an alternative solution, which has a separate nozzle heater for the sprue area, is also encompassed by the present invention.

The detailed illustration also shows, by means of drawn-in dotted lines with arrows, how the melt flow takes place in the last section of the nozzle channel 41 up to the sprue area 42 . In the exemplary embodiment shown, the sprue region 42 has an annular sprue geometry. This is formed in that the melt channel 41 has a central conductor 61 in the vicinity of the sprue region 42, which guides the melt outwards into a cylindrical gap, from which the ring-shaped sprue geometry results. Shows other advantageous sprue geometries 8 .

4 shows a schematic sectional view of an embodiment of a detail of the die-casting nozzle 40 according to the invention in the sprue area 42. Here, as already in FIG 3 , the melt flow in the nozzle channel 41 marked.

An important feature of the die casting nozzle 40 of the present invention is shown in the gate area 42 . This includes a tear-off edge 60, which can be designed on one side or both sides, ie inside on the central conductor 61 and/or outside on the lower section of the melt conductor 41 as a circumferential elevation in each case. Shown is a two-sided design indoors and outdoors, where the Tear-off edge 60 causes a cross-sectional reduction between the product, consisting of the solidified melt, and the "frozen" sprue area, the melt slug formed there. This reduction in cross-section forms a predetermined breaking point at which the product tears off the melt slug in the sprue area in a defined manner and ensures that the product has a clean sprue that does not require any reworking.

figure 5 shows a schematic representation of an embodiment of the die casting nozzle system 10 according to the invention, similar to the representation from FIG 3 with a detailed view of the sprue area 42, which shows the movable mold half 34 and the cavity 36 in addition to the fixed mold half 32.

Compared to the embodiment 3 however, there are a number of differences. These relate to the surroundings of the sprue area 42 and the nozzle heater 44. The latter is placed in a peripheral groove in the body of the die-casting nozzle 40.

A part of the fixed mold half 32 is shown at the sprue area 42 and is designed in such a way that an insulating air space 58 is formed between this and the die-casting nozzle 40 . Furthermore, a temperature sensor 62, connected via a feed line 63, is arranged in this area. The duct for the supply line can also be used for a supply line for the heating in the detailed view.

6 shows in a schematic sectional view, including a detailed view, an embodiment of the die-casting nozzle system 10 according to the invention, which is the in the Figures 3 and 5 illustrated differs again in the type of heating and the design of the sprue area 42. An insulating ring 59 , for example made of titanium alloy, is used in the sprue region 42 to improve the thermal insulation with respect to the fixed mold half 32 . This is arranged on the sprue area 42 and surrounds it in the area of the radial seat 24.

In the exemplary embodiment shown, the die-casting nozzle 40 is heated via a printed nozzle heater 45 which is applied in a spiral shape to the body of the die-casting nozzle 40 and is protected by a movable protective sleeve.

7 shows a further embodiment of a die-casting nozzle 40' according to the invention in a schematic sectional representation, which differs significantly from the embodiments described above. It has a nozzle heater 46, which is designed as an internal heating element. The nozzle heater 46 is surrounded by the nozzle channel 41, which as a result has the shape of a hollow cylinder. As a result, the thermal heat can very easily be brought directly up to the sprue area 42, without the heat dissipation having to be counteracted by special measures for thermal insulation. This embodiment is particularly advantageous for the use of melts with a melting temperature of over 600° C. or in the case of a multiple sprue, with which several closely spaced cavities can be supplied with melt from a die-casting nozzle.

The hollow-cylindrical nozzle channel 41 has no non-return valve; this is to be arranged in the melt channel of the melt distributor when such a die-casting nozzle 40' is used.

The nozzle channel 41 transitions into the sprue area 42, which in the present exemplary embodiment has a punctiform design.

More sprue molds are in the 8 shown.

View a) shows a gate geometry of a multi-nozzle, which makes it possible to fill a multi-mould. The melt then not only shoots into one cavity, but into several closely spaced cavities, so that several parts can be manufactured with one nozzle.

View b) shows a sprue geometry, as shown in section from the Figures 2 to 6 emerges and is designed as an annular sprue with a large cross section for short casting times. The point inside the ring, the central conductor 61 (cf. Figures 3 and 4 ), ensures heat conduction from the heated nozzle body into the sprue area and is made of a particularly thermally conductive material, for example a suitable alloy. As a result, after the product is torn off and the heat sink is no longer available, any solidified melt in the sprue area is quickly melted again, so that a new die-casting cycle for the production of another product can begin.

This also contributes in particular if the entire sprue area is made of the particularly thermally conductive material.

View c) supplements the ring-shaped sprue with a punctiform sprue arranged centrally in the ring, so that an even larger melt volume flow can be achieved. A punctiform sprue can also be provided without the additional annular sprue. Such a variant can already be found in the in 7 die-casting nozzle 40 shown.

Views d) to f) each show a sprue geometry that promises faster injection of the melt into the cavity with similar stability in the sprue area, especially if it has a larger volume. For this purpose, grooves in the sprue area starting laterally from the ring-shaped sprue geometry are used in the form of a line, two crossed lines or as a star-shaped sprue geometry.

Reference List

1

warm chamber system

2

hot chamber die casting machine

3

casting container

4

melt

5

Pistons

6

piston drive

7

machine nozzle

10

die-cast nozzle system

12

machine nozzle approach

20

melt spreader

22

melt channel

24

radial seat

26

axial fit

30

mold

32

fixed mold half

34

movable mold half

36

cavity

36'

product

40,40'

die cast nozzle

41

nozzle channel

42

sprue area

43

Nozzle heater (sleeve)

44

Nozzle heater (circumferential groove)

45

Nozzle heater (movable sleeve)

46

Nozzle heater (internal heater)

48

check valve

50

sprue insulation

58

isolation room

59

insulating ring

60

tear-off edge

61

central leader

62

temperature sensor

63

supply line

Claims (11)

1. A diecasting nozzle system (10) for use in a hot-chamber system (1) for diecasting metal melt (4) according to the hot-chamber approach, in which the melt is held in a liquid state at a sprue of a mold, the hot-chamber system (1) comprising a hot-chamber diecasting machine (2) with a casting vessel (3) and a machine nozzle (7), via which the melt enters the diecasting nozzle system (10), the diecasting nozzle system (10) comprising at least one upper and at least one lower diecasting nozzle (40), each having a sprue region (42), and a melt distributor (20) which distributes the melt (4) uniformly from the machine nozzle (7) among the diecasting nozzles (40), wherein at least one nonreturn valve (48) is arranged between the sprue region (42) of the diecasting nozzles (40) and the casting vessel (3), wherein the nonreturn valve (48) prevents the melt (4) from flowing back away from the sprue region (42) in the direction of the casting vessel (3), characterized in that the nonreturn valve (48) is in each case arranged between the sprue region (42) of at least the at least one upper diecasting nozzle (40) and a last branch of melt runners (22) in the melt distributor (20) of the hot-chamber system (1) to the at least one upper diecasting nozzle (40).
2. The diecasting nozzle system according to claim 1, wherein a thermal protective device, which reduces heat dissipation from the sprue region (42) in the direction of a casting mold (30), is provided in the sprue region (42) of each diecasting nozzle (40).
3. The diecasting nozzle system according to claim 2, wherein the thermal protective device is configured as a thermal insulator (58, 59) in the sprue region (42) or as a counter-heater arranged in the sprue region to reduce heat dissipation, wherein the counter-heater is configured as a segment that is arranged around the sprue region (42) and can be temperature-controlled separately, and/or as a separately heated sprue region (42).
4. The diecasting nozzle system according to claim 3, wherein the thermal insulator is configured as an insulating ferrule (58) made of a material with a low heat conductivity surrounding the sprue region (42), as a sprue insulator (50) configured as an insulating air, gas or vacuum layer inside the sprue region (42), and/or as an insulating space (58) between the body of the diecasting nozzle (40) and the casting mold (30).
5. The diecasting nozzle system according to claim 4, wherein a device that uses a CO₂ cycle is provided for operation of the counter-heater.
6. The diecasting nozzle system according to any of claims 1 to 5, wherein a nozzle channel (41) in the sprue region (42) of the diecasting nozzle (40) includes a separation edge (60) at an outer circumference of a central duct (61) and/or at an inner circumference of the nozzle channel (41), wherein said separation edge (60) is designed such that it forms a breaking point in the melt (4) solidified in the sprue region (42) where a product (36') separates when the sprue region (42) is lifted off the casting mold (30).
7. The diecasting nozzle system according to any of claims 1 to 6, wherein a temperature sensor (62) is arranged in the sprue region (42).
8. The diecasting nozzle system according to any of claims 1 to 7, wherein the nonreturn valve is arranged in the nozzle channel (41) of the diecasting nozzle (40).
9. The diecasting nozzle system according to any of claims 1 to 8, wherein the nonreturn valve is configured as a freely moving ball cooperating with a valve seat.
10. A diecasting method, which uses a diecasting nozzle system according to any of claims 1 to 9, characterized by the following method steps:

    • fitting the permanently and uniformly heated diecasting nozzles (40) onto the casting mold (30);

    • opening the at least one nonreturn valve (48) during injection of the melt (4) through the melt runner (41) and the sprue region (42) into the casting mold (30);

    • solidifying the melt (4) to obtain a product (36') inside the casting mold (30) including the sprue region (42), wherein heat flows from the sprue region (42) into the product;

    • lifting off the diecasting nozzle (40), separating the product (36'), and non-occurrence of heat dissipation from the sprue region (42);

    • melting the solidified melt in the sprue region (42) of each of the diecasting nozzles (40) through continued heat flow from the diecasting nozzle (40), wherein melt (4) flowing from the upper diecasting nozzles (40) via the melt distributor (20) is prevented from flowing out of the at least one lower diecasting nozzle (40) in the melt distributor (20) by closing at least the nonreturn valve (48) in the region of the at least one upper diecasting nozzle (40).
11. The diecasting method according to claim 10, wherein the diecasting nozzle (40) can be heated from inside and/or from outside in the region of a body of the diecasting nozzle (40) and comprises the sprue region (42) made of a material that has a heat conductivity corresponding at least to the heat conductivity of the melt and/or can be heated separately.

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