Die casting nozzle and method for operating a die casting nozzle

Abstract

Die cast nozzle for use in a die casting hot chamber system for molten metal with at least melting channel (4) in a channel carrier (3) that can be connected to a melt distributor (21), wherein the melting channel (4) passes over into a heating zone (6) and a nozzle tip (8), to which a sprue area (10) is attached, in which a plug of solidified melting can be formed that interrupts the melting flow, wherein the heating zone (6) comprises a heating cartridge (2) and/or a heatable nozzle shaft (33) and/or the nozzle tip (8) is comprised as heatable nozzle tip (8) and comprises at least one heating cartridge (2), the heatable nozzle shaft (33), or the heatable nozzle tip (8) as heating element with electric heating, which comprises high power density in at least one section and low thermal inertia, comprised in a way that a temperature change gradient of 20 to 250 K/s, preferably 150 K/s, can be achieved on the surface of the heating element. A method for operating the die cast nozzle is also the subject matter of the invention.

Claims

1. A die cast nozzle for use in a die casting hot chamber system for molten metal with at least one melting channel (4) in a channel carrier (3) that can be connected to a melt distributor (21), wherein the melting channel (4) passes over into a heating zone (6) and a nozzle tip (8), to which a sprue area (10) is attached, in which a plug of solidified melting can be formed that interrupts the melting flow, characterised in that the heating zone (6) comprises a heating element with electric heating, that comprises in at least one section materials with low density and high thermal conductivity, providing a high power density and low thermal inertia, such that a temperature change gradient of 20 to 250 K/s can be achieved on the surface of the heating element, wherein the die cast nozzle comprises a nozzle body (5) that encases the channel carrier (3) and the nozzle body (5) or the channel carrier (3) are comprised of titanium.

2. The die cast nozzle according to claim 1, characterised in that the nozzle tip (8) is comprised of ceramic.

3. The die cast nozzle according to claim 1, characterised in that the melting channel (4) comprises a channel coating (20).

4. The die cast nozzle according to claim 1, characterised in that at least one thermal sensor (41) is included for determining the melting temperature in the heating zone (6) and/or the sprue area (10).

5. The die cast nozzle according to claim 1, characterised in that at least one cross-section change (14) is included that limits the heat flow up to the sprue area (10).

6. The heating element for a die cast nozzle according to claim 1, characterised in that at least partially a layer structure comprised of an insulator ceramic (15) and at least one heating conductor are included, wherein the insulator ceramic (15) forms at least on one exterior of the heating element and around at least one heating conductor an electrically insulating barrier and that the heating conductor can be contacted electrically via contacts (11, 11).

7. The heating element according to claim 6, characterised in that the heating conductor is comprised of a conductor ceramic (16) or a metal conductor.

8. The heating element according to claim 6, characterised in that the heating element comprises at least one surface coating (13) or an internal insert (31).

9. The heating element according to claim 6, characterised in that at least one of the heating elements comprises an individually controllable heating conductor.

10. A heating cartridge with electric heating for a die cast nozzle according to claim 1, characterised in that the heating cartridge (2) comprises a shaft (19) that is extended to a head (44) that leads through the melt distributor, so that the contacts (11, 11) are outside of the melt distributors.

11. The heating cartridge according to claim 10, characterised in that a compensating device for balancing different thermal expansions of the channel carrier (3) and the heating cartridge (2) inserted into the channel carrier (3) is included, wherein the channel carrier (3) comprises a seat (12) for the heating cartridge (2), against which the heating cartridge (2) is pressed, wherein an expansion bolt (39), comprising a pressure screw (40) that is in connection with the channel carrier (3) in a force application zone is included, which is in connection to the heating cartridge (2) in a contact zone, so that the heating cartridge (2) is pressed against the seat (12) by the expansion bolt (39) when the channel carrier (3), heating cartridge (2) and expansion bolt (39) are heated.

12. Method for operating a die cast nozzle according to claim 1, characterised in that the steps operation of one or several heating elements with electric heating with low thermal inertia and a power density in at least one section that is sufficiently high, so that a temperature change gradient of 20 to 250 K/s can be achieved on the surface of the heating elements, wherein operation ensues with increased power, injection of the melting into a mold immediately afterwards or at the same time, reduction of power of the heating element or the heating elements or their complete deactivation, stopping the melting flow, operation of the heating element or the heating elements with such power that the melting in the heating zone (6) remains liquid, but the heat is not sufficient to maintain the melting on melting temperature in the sprue area (10) as well, wherein the melting solidifies to a plug, seals the injection point (23) and subsequent flow or reflowing of the melting is prevented.

13. Method according to claim 12, characterised in that the portion of heat flowing from the heating area (17) of the heating cartridge (2) into the sprue area (10) is at least determined by one cross-section change (14) and/or the melting is tempered in the sprue area (10) via the heatable nozzle tip (8) and/or the separately heatable tip area (18) of the heating cartridge (2), wherein at least one cross-section change (14) minimises the interaction between tip area (18) and heating area (17).

14. Method according to claim 13, characterised in that a thermal sensor (41) provides a temperature value of a melting temperature to a temperature control system that regulates the melting temperature in the heating zone (6) and/or in the sprue zone (10), so that the melting temperature is only insofar above the melting temperature of the melting that a safe melting flow is ensured.

15. The die cast nozzle according to claim 1, characterised in that the temperature change gradient 150 K/s can be achieved on the surface of the heating element.

16. The die cast nozzle according to claim 1, characterised in that the heating zone (6) comprises a heating cartridge (2).

17. The die cast nozzle according to claim 1, characterised in that the heating zone (6) comprises a heatable nozzle shaft (33).

18. The die cast nozzle according to claim 1, characterised in that the nozzle tip (8) is a heatable nozzle tip (8).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the invention can be found in the figures and their description. They show:

(2) FIG. 1a: a schematic sectional view of an embodiment of a die cast nozzle with cartridge heating according to the invention;

(3) FIG. 1b: a schematic sectional view of an embodiment of another die cast nozzle with cartridge heating according to the invention;

(4) FIG. 2: a schematic sectional view of an embodiment of a heating cartridge according to the invention in sectional cut;

(5) FIG. 3: a schematic sectional display of an embodiment of a die cast nozzle according to the invention with cartridge and shaft tip heating as well as lateral gating;

(6) FIG. 4: a schematic sectional display of an embodiment of a die cast nozzle according to the invention with cartridge and shaft tip heating;

(7) FIGS. 5a and 6 to 9: a schematic top view of a sprue schematic of a die cast nozzle according to the invention respectively;

(8) FIG. 5b: a schematic sectional display of a detail of an embodiment of a die cast nozzle according to the invention for lateral gating;

(9) FIG. 10: a schematic sectional display of an embodiment of a die cast nozzle according to the invention as coil tube cartridge; and

(10) FIG. 11: a schematic sectional display of a detail of an embodiment of a die cast nozzle according to the invention with tip heating and internal insert.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(11) FIG. 1a shows a schematic sectional display of an embodiment of a die cast nozzle according to the invention 1 with a heating cartridge 2, which is contacted by electric connections 11, a channel carrier 3, in which the melting channels that are designed as double in the presented embodiment are introduced, a nozzle body 5, which encases the channel carrier 3 and a nozzle tip 8 at the end of the die cast nozzle 1 facing the casting mold 22. The melting channels 4 run from an eccentric entry position of the melting from the melt distributor to a central bore in the nozzle shaft 33, the heating zone 6 and are protected in a preferred embodiment against the particularly corrosive effects of the melting by a channel coating 20. With this, a steel channel carrier 3 cannot form an alloy with the melting, nor be damaged in another way. As channel coating 20, enamel is used in the particularly preferred embodiment.

(12) The melting channels 4 are formed in a way, so that they can be connected to the melt distributor 21 only implied in FIG. 1 and are supplied with melting by it. The melting channels 4 lead to heating zone 6, which is also a part of the melting channel 4 and in which the heating cartridge 2 with the heating area 17 extends into. With this, the melting can be heated if it is in heating zone 6 in nozzle shaft 33.

(13) The heating cartridge 2 is also provided with a coating 13 in an alternative embodiment, which is similar to the channel coating 20 and protects the concerned surfaces against corrosion, adherence of slag or undesirable alloys. This particularly applies, if it is a heating cartridge 2 that is not made of ceramic.

(14) The die cast nozzle 1 furthermore has a nozzle top 8 that is connected to the channel carrier 3 in the direction of a casting mold 22 that is only implied in FIG. 1. The nozzle tip 8 has in its centre an area tapering towards the injection point 23, in which the melting is oriented towards escaping from the die cast nozzle 1 at the sprue area 10. The nozzle tip 8 is planned as exchangeable in the preferred embodiment, so that this highly stressed component can be replaced easily upon wear, without the need to deactivate the entire die cast nozzle 1. It is particularly preferred to use highly wear-resistant material such as ceramic for the production of the nozzle tip 8. With this, the particularly high service life is ensured in spite of the high stress due to the melting that is discharged from the sprue with high velocity.

(15) For reducing heat loss from the die cast nozzle 1, the area through which the melting flows, the channel carrier 3, is insulated. The insulation is preferably made by a nozzle body 5, whose heat transfer to the casting mold 22 is reduced, because the nozzle tip 1 only supports itself in the area of the supporting rings 7 on the casting mold 22. Another reduction of heat transfer is made by using an insulator 9 between channel carrier 3 and nozzle body 5. Air can also be used for this.

(16) The permanently safe and fixed seat of the heating cartridge 2 in channel carrier 3 is ensured by a seat 12 of centring guidance.

(17) The end of the heating cartridge 2 that points to the injection point 23 is formed by a preferably conical tip area 18. This forms in cooperating with the internal recess of the nozzle tip 8 a hollow-cone shaped space that is tapered off to the injection point 23 and through which the melting must flow with high velocity, before it escapes the die cast nozzle 1 via injection point 23. As soon as the melting cools down in this space of the sprue areas 10, it forms a tight plug that prevents escaping or reflowing of the melting and which does not loosen from the sprue area 10, even after it starts to melt when the heating begins and is loosened from the walls. The melting itself ensues fairly quickly and evenly, because the preferred hollow-cone shape of the plug has only a low wall thickness than a full profile and it can be heated up quickly.

(18) The very quick solidification of the plug is facilitated by the fact that the melting flowing through the narrow space in sprue area 10 further heats itself during flowing due to friction and is still fluid when the cooling of tip area 18 begins. However, if the melting flow stops, not frictional heat occurs anymore and the melting solidifies immediately to the plug sealing sprue 10.

(19) For re-fusing the plug, the heating area 17 of the heating cartridge is heated in the presented embodiment, so that the temperature of the melting in the heating zone 6 also rises. With this, the heat is guided on the one hand via the melting to the plug and on the other hand through the zone of cross-section change 14 to the tip area 18. With the formation of the cross-section change 14 it can be controlled, to what extent the heat is transferred to the tip area 18. This way, the time of re-fusing can be controlled subject to the temperature that the heating area 17 reaches.

(20) FIG. 1b shows a schematic sectional display of another embodiment of a die cast nozzle 1 according to the invention with cartridge heating using heating cartridge 2. The heating cartridge 2 has a head 44 here that is formed cylindrically and is pressed against a seat 12 in the bore of channel carrier 3 by an expansion bolt 39 in connection with a pressure screw 40. Here, the pressure screw 40 generates a pre-tension of the expansion bolt 39, connected with a force effect to the head 44 of the heating cartridge 2.

(21) If the die cast nozzle 1 commences operation, all components are heated to operating temperature, which approaches 450 C. in the preferred method. As a consequence, expansion of components subject to heat ensues, where metal elements such as channel carrier 3 expand more than ceramic elements such as the heating cartridge 2. As a result, the heating cartridge 2 would loosen in its seat 12.

(22) This is however prevented by the use of a pre-tensioned expansion bolt 39, which also expands significantly such as channel carrier 3 in an expansion area and which counteracts a loosening of seat 12. The expansion area stretches from 12 up to the end of the thread in a slot nut positively connected to channel carrier 3, in which the pressure screw 40 intervenes. Instead, the recorded pre-tension of seat 12 is maintained by the pressure screw 40 and the heating cartridge 2 remains fixed on its head 44 fest in its seat 12. Due to appropriate design in the thermal expansion of cooperative elements, here channel carrier 3 and expansion bolt 39, an increase of tension can be generated here. This would result in a better force fit during operation without bringing the attached element, the head 44 of the heating cartridge 2, to flowing by strong permanent pressure load, if the material used for this should lean towards such an effect.

(23) For the reduction of heat flow from the die cast nozzle 1, a supporting ring 7 as well as a pressure piece 38 are planned. With these elements, the die cast nozzle 1 supports itself on the casting mold 22 during the casting process, if it drops down to the casting mold 22 during the casting process. Due to selective dropping down and the use of material with low heat conductivity, the heat flow from the die cast nozzle 1 into casting mold 22 is reduced. In the area of nozzle tip 8, an insulator 9, preferably an air space, is planned. Alternatively or additionally, an insulating element, for example a disc made of titanium is planned for arrangement in the area of the front surface 43 of nozzle tip 8, in order to prevent the discharge of heat directly into the sprue area of the casting mold.

(24) A cross-section change 14, here in the cross-section in the melting channel 4, takes care of the defined heat transfer via the melting in the sprue area 10 of nozzle tip 8. Alternatively or additionally, a cross-section change of the heating cartridge 2, according to FIG. 1a, is planned. Additionally, another cross-section in the form of a tear-off edge 42 is planned in the presented embodiment. This does not only prevent heat discharge into the casting mold via the melting, but also provides a pre-determined breaking point for the solidified melting, on which the solidified melting shrinking during cooling tears off from the item even before the molding process. If the nozzle tip 8 is comprised of titanium as in the preferred embodiment, an internal insert, preferably comprised of resistant ceramic or tungsten, is an advantage in the sprue area 10, because the melting that flows there with high velocity would otherwise cause extensive wear.

(25) The use of a thermal sensor 41 has proved to be particularly advantageous. This is arranged near the sprue area 10 in the nozzle tip 8 preferably comprised of insulating titanium in the preferred embodiment. The measured temperature value that the thermal sensor 41 delivers is preferably processed in a control system. This will then provide exact temperature guidance subject to time in every section of the die casting process with the result of an effective use of energy as well as minimum thermal load on the elements guiding the melting. With this, special measures for preventing thermal wear or undesirable alloys such as coating can be omitted.

(26) The melting channel 4 runs from the connection area with the melt distributor through the channel carrier 3 deviating from the vertical, until it comes up to the heating zone 6, which receives the heating cartridge 2, and runs further in the heating zone 6 to the nozzle tip 8. Heating area 17 and tip area 18 merge into each other in this embodiment of the heating cartridge 2 with cross-section change. The internal insert 31 mitigates wear and increases the service life of nozzle tip 8.

(27) FIG. 2 shows a schematic display of an embodiment of a heating cartridge 2 according to the invention in sectional cut, which shows the heating area 17. There, a multi-layer structure of the heating system can be seen, which in the particularly preferred embodiment has as a central core as well as circumference and for insulation of the conducting areas from each other an insulator ceramic 15 respectively. Embedded between these in the presented embodiment of concentric layers is the conductor ceramic 16, which serves as heating system using its electrically conducting properties. The individual conductor loops are also preferably electrically insulated against each other by insulator ceramic 15.

(28) Heating cartridges 2 comprised of high-performance ceramics are particularly well suited for die cast nozzles with short cycle times, which must be heated with quickly changeable heating requirement.

(29) Even though full ceramic heating elements heating elements with insulating and conducting ceramic are basically known, wherein the heating function in the previous application according to the state of the art is only integrated into high-strength ceramics such as cutting knives, welding jaws and tools. The ceramic heating element according to the invention is integrated in a totally different way than the state of the art, in particular into a die cast nozzle as heating system, wherein it is controlled highly dynamically by using its thermal properties.

(30) As materials in the preferred embodiment of the heating cartridge 2 according to the state of the art, known ceramics are used that have various advantages compared to metal heating elements. Particularly favourable is the high surface power of up to 150 W/cm.sup.2 and the radiation emission of e>0.9, wherein temperatures of up to 1000 C. can be reached, which is of particular interest for refractory non-ferrous metals such as aluminium, which can be processed in the die casting process.

(31) Other advantages include short heating-up times, minor residual, which facilitates quick cooling down, and a very high controllability due to minor thermal mass. Particularly due to the minor thermal capacity of the ceramic because of its low density, high heating rates can be realised with low energy intake. High heat conductivity and minor mass of the ceramic heating body ultimately cause low thermal inertia.

(32) The full ceramic heating elements are resistant against oxidation and acids. They have low wettability with liquid metals, high mechanical strength, high heat conductivity as well as high electric insulation resistance and high disruptive strength at the same time. They also have high hardness and fine wear-resistance.

(33) Attributable to fine and safe electric insulation to the outside, the heating cartridge 2 can be operated with higher voltages, preferably 230 V. This has the advantage that less current strength must be conducted to the heating system and the cross-section of the feed lines can be correspondingly small. Saving of costs and minor power loss are the result. With the preferred power of 400 W, only a current strength of 1.8 A is required.

(34) The electrically conducting ceramic and the shell of insulating ceramic are sintered to a homogeneous body and therefore facilitate very high power densities with high mechanical stability at the same time. The fine resistance to age and wear ensures long service life even with high temperatures.

(35) Alternative embodiments plan however, to use other materials for the heating cartridge 2, such as steel. Particularly in this case, a coating 13, preferably enamel, is required to produce corresponding surface properties, primarily to reduce wear. Next to high wear-resistance, the prevention of oxidation under the influence of aggressive melting and a minor tendency of adherence for metals on the surface shall be achieved.

(36) The heating cartridge is alternatively manufactured from a ceramic with at least one metal conductor integrated into it, wherein the metal conductor is prepared as metal powder, preferably refractory, as massive conductor or prepared in a lithographic procedure and introduces as a film. For this, preferably procedures such as thick-film technology, HTCC or LTCC are planned.

(37) A particularly preferred embodiment of the heating cartridge 2 provides for separated heating in heating area 17 and the tip area 18, which can also be controlled individually via the electric connections 11, 11. With this, the heating area 17 can be continuously supplied with as much energy to keep the melting liquid in a particularly energy-saving manner. The tip area 18 however, can be heated and cooled down in a clocked, targeted manner, so that solidification and re-fusing of the little amount of melting that is present in the periphery of the tip area 18 is made possible. Via the cross-section change 14, the mutual influence of the heating area 17 and the tip areas 18 is minimised and the independent function of both areas is supported.

(38) Furthermore planned is the heating of only the tip area 18 or other delimited areas of the die cast nozzle.

(39) The shaft 19, which is shown as interrupted, preferably has such a length that is stands out from upwards from the melt distributor, that the contacts 11, 11 are easily accessible and a cable duct through the melt distributor is avoided by this.

(40) FIG. 3 shows a schematic sectional display of an embodiment of a die cast nozzle 1 according to the invention with cartridge and shaft tip heating and lateral gating 34, here with injection mold 24 in the shape of a star for producing the items 29. A nozzle shaft 33 is used for this, which can be heated directly and that has a structure of an insulator ceramic 15 and conductor ceramic 16 for this, similar to the heating cartridge 2 described above. A special feature is that the nozzle shaft 33 and the nozzle tip 8 are designed in one piece and can be heated. Preferably, the largest portion of heating power is generated in the area of the nozzle tip 8, particularly preferably in the first 1 to 15 millimeters when viewed from the injection point 23. Enough heating power is entered here that the heat drop in the front area of the nozzle is compensated. This depends of external factors such as thermal insulation and heat-conducting contact surfaces.

(41) Thereby even heating of the melting is achieved by both the heating cartridge 2 as well as the nozzle shaft 33. The electric connections 11, 11 is made from the outside here, for example via head plate 35, where the die cast nozzle 1 is in contact with the melt distributor.

(42) Alternatively to this, a melting temperature in the area of heating cartridge 2 that is overall too high can be countered by operating it with low temperature or entirely unheated. So you do not need to make sure that sufficient heat flows into the tip area 18. Rather the temperature conditions in the area of only the nozzle tip 8 can be controlled in a targeted manner.

(43) Instead of the presented peaked shape of the heating cartridge 2, it is alternatively planned here that it maintains its cylindrical shape and the full diameter up to injection point 23 and that it increases the ring diameter of the sprue 25 from FIG. 6 in such a manner that the production of several parts is facilitated by lateral injection or parts with larger dimensions can be produced. An extension of the heating cartridge 2 diameter in the tip area 18 is planned and preferred in particular.

(44) Furthermore, a solution is given preference, in which the entire die cast nozzle 1 in the outer area of a nozzle body 5 comprises a sheath of titanium or has at least an insulating air layer towards nozzle shaft 33.

(45) FIG. 4 shows a schematic sectional display of an embodiment of a die cast nozzle 1 according to the invention with cartridge and tip heating. Here, a nozzle shaft 33 is used that cannot be heated. A separate nozzle tip 8 is planned for heating the melting, which also has conductive and insulating ceramics corresponding to the description mentioned above and which can therefore be heated. The electric connection that is required for this is preferably introduced via the nozzle shaft 33 to the head place 35 or conducted through the nozzle body 5 directly to the outside. With this, a favourable structure is achieved, because only in the area of the nozzle tip 8 a heating ceramic is required, where particularly high temperatures and most of all high dynamics between melting and solidifying temperature are required. Next to this, the tip area 18 is also designed as heatable.

(46) FIG. 5a shows a schematic top view of a sprue pattern of a die cast nozzle according to the invention in the mold of a star 24 and lateral sprue 34. An item 29 is furthermore indicated, a product of the planned die casting process. This is produced using the star mold 24 of the sprue in lateral gating 34. With this, several parts can be produced with one die cast nozzle without a channel system that would result in a solidified so-called tree upon molding, which would have to be separated from the item. In the present case with the example of the presented sprue structure in the mold of a star 24 these are six items 29 that can be produced in one process.

(47) FIG. 5b with the nozzle tip 8 shows a schematic sectional display of a detail of an embodiment of a die cast nozzle according to the invention with lateral gating 34, wherein the injection point is sealed by a nozzle plug 37. Here, a nozzle tip, a nozzle ring or a nozzle bar is planned depending of the specific shaping of the structure of the nozzle tip 8, both heated and unheated versions. Furthermore, a separate nozzle seal 37 is also comprised just as a nozzle tip in one piece without opening in the injection point. Openings in the wall of nozzle tip 8 are planned as lateral sprue 36 for discharging the melting into the laterally arranged sprue area of the casting mold that is not displayed.

(48) Here, a rotationally symmetric arrangement around a conical wall of nozzle tip 8 is according to the invention just as an elongated nozzle tip 8, in which the lateral sprues are arranged linear in series. The preferred structure of the heating ceramic nozzle comprised of insulation ceramic 15 and conductor ceramic 16 is displayed.

(49) FIG. 6 shows a schematic top view of a sprue pattern of a die cast nozzle according to the invention in the mold of a ring 25. Such a mold is created, just as shown in FIG. 1, when the tip area 18 reaches up to the injection point 23. If a larger ring diameter is required, this can be achieved by a larger diameter of the tip areas 18 at the injection point 23.

(50) FIG. 7 shows a schematic top view of a sprue pattern of a die cast nozzle according to the invention in the mold of a point 26. In contrast to the ring mold 25 shown in FIG. 6, this mold 26 is achieved, if there is no tip area 18 according to FIG. 1 and instead, just as shown in FIG. 10, the stumpy heating cartridge 2 does not reach into the nozzle tip 8.

(51) FIG. 8 and FIG. 9 show a schematic top view of a sprue pattern of a die cast nozzle according to the invention in flat mold 27 or in the mold of a cross 28. The basic structure of the die cast nozzle corresponds to the one described in FIG. 7, meaning without the tip area 18 reaching too far into the nozzle tip 8. The mold of the sprue 23 as a flat mold 27 is the result of the corresponding molding of nozzle tip 8. Particularly advantageous is a flat mold 27 for items with large longitudinal extension. An even flow of melting material into four directions however is achieved by applying the mold of a cross 28.

(52) It is furthermore planned that the abovementioned injection molds can be evoked by a respectively exchangeable tungsten disc with the corresponding injection mold, which is set to the nozzle at injection point 23. With this, different injection molds can be applied without having to change the die cast nozzle 1 altogether.

(53) FIG. 10 shows a schematic sectional display of an embodiment of a die cast nozzle 1 according to the invention with twisted pipe 30. With this, the entire nozzle body 5 can be heated in the external area. The twisted pipe 30 is placed around the outer sheath. By heating it, the entire die cast nozzle 1 receives a more even temperature distribution and the energy input into the heating cartridge 2, the nozzle shaft 33 or the nozzle tip 8 can be made with less energy input. The energy applied to the elements mentioned last can therefore have higher dynamics in the interest of faster casting processes and shorter cycle times according to the description of plug formation in the sprue area mentioned in the beginning. Also, the thermal load of sensitive melting, primarily plastics, is lower.

(54) FIG. 11 shows a schematic sectional display of a detail of an embodiment of a die cast nozzle according to the invention with tip heating and internal insert 31, comprised as heating ceramic nozzle 32. Here in the presented embodiment, a nozzle tip 8 with a ceramic structure is applied to a nozzle shaft as described in FIGS. 2, 3, and 4. Due to the structure of the insulator ceramic 15 and the conductor ceramic 16, a high conductor density is generated in this area, through with much heating power can be introduced to this area. The nozzle tip 8 represents only a very small quantity of material compared to the other components of the die cast nozzle, so that heating and cooling down are possible with very high dynamics and quick changes of the cycle. The power density can be set for every section by the cross-section of the conducting areas of conductor ceramic 16, and by corresponding abatement. These parts are overwrought after burning for giving them their exact shape and a layer of insulator ceramic 15 always remains on the outside.

(55) In order to prevent wear on the highly stressed internal sheath, the surface that comes in contact with the melting, a coating, but particularly preferably an internal insert 31 is used here. This is comprised of tungsten, but also other materials with high resistance to wear, high melting point and high heat conductivity such as ceramic conducting heat are used.

(56) In alternative embodiment, where the nozzle tip 8 is comprised of steel, but particularly if it is comprised of titanium, an internal insert 31 that reduces wear is of particular importance. In comparison it is planned for a nozzle tip 8 comprised of ceramic, in turn a very sturdy, wear-resistant material not prone to chemical bonds or alloys, to dispense with the use of an internal insert 31. An outer insulation not presented here is however planned for the preferred embodiments of both versions in order to avoid heat discharge from the die cast nozzle.

(57) The reduction in wear ensues alternatively or additionally to the abovementioned measures using a special method. It has proven to be favourable, if the power of the heatable elements in the sprue area is controlled in a manner that the wear of the sprue areas is minimised. The control system only provides as much power as is needed for re-fusing the melting plug in the sprue area. With this, the wear in the die cast nozzle in the sprue area is further reduced. The control of the thermal power ensues according to the material of the melting as well as other parameters of the die cast nozzle such as injection geometry.

(58) Alternatively to a control by fixed parameters it is planned that a regulation processes values measured by sensors and thereby determines the heating power accordingly. As sensors, temperature sensors in the area of the die cast nozzle, but also other sensors such as pressure sensors in the melting channel are planned. Temperature sensors are particularly preferred for this in the area of the melting channels inside and/or on its outer wall as well as alternatively or additionally pressure sensors used in the interior of the melting channel 4 or the sprue area 10 as shown in FIG. 1.

(59) Particular advantages of the method according to the invention lie in the accessibility of high cycle times and minor wear of the die cast nozzle. The die casting hot channel system without sprue that comprises the die cast nozzle according to the invention also facilitates highly reproducible conditions, which result in a high, even cast part quality. Particularly the wall strengths of the cast parts can be minimised by this increased quality with corresponding saving of materials and weight.

LIST OF REFERENCE NUMERALS

(60) 1, 1 Die cast nozzle 2, 2 Heating cartridge 3 Channel carrier 4 Melt channel 5 Nozzle body 6 Heating zone 7 Supporting ring 8,8,8 Nozzle tip 9 Insulator 10 Sprue area 11, 11 Electric connection 12,12 Seat 13 Coating 14 Cross-section extension 15 Insulator ceramic 16 Conductor ceramic 17 Heating area 18 Nozzle tip section 19 Shaft 20 Channel coating 21 Melt distributor 22 Casting mold 23 Injection point 24 Injection mold star 25 Injection mold ring 26 Injection mold point 27 Injection mold flat 28 Injection mold cross 29 Item 30 Twisted pipe 31 Internal insert 32 Heating ceramic nozzle 33, 33 Nozzle shaft 34 Lateral gating 35 Head plate 36 Lateral sprue 37 Nozzle seal 38 Pressure piece, supporting element 39 Expansion bolt 40 Pressure screw 41 Thermal sensor 42 Tear-off edge 43 Front surface