Diecasting die system

Abstract

The invention relates to a diecasting method and a diecasting nozzle system (10) for use in a hot-chamber system (1) for the diecasting of metal melt (4), comprising a hot-chamber diecasting machine (2) with a casting vessel (3) and a melt distributor (20), which distributes the melt (4) from a machine nozzle (7) among uniformly heated diecasting nozzles (40). Arranged between a sprue region (42) of the diecasting nozzles (40) and the casting vessel (3) is at least one nonreturn valve (48), which prevents the melt (4) from flowing back from the sprue region (42) in the direction of the casting vessel (3). According to the invention, the nonreturn valve (48) is respectively arranged between the sprue region (42) of at least the upper diecasting nozzles (40) and a final branch of melt runners (22) in the melt distributor (20) to each of the diecasting nozzles (40).

Claims

1. A diecasting nozzle system (10) for use in a hot-chamber system (1) for the diecasting of metal melt (4), comprising a hot-chamber diecasting machine (2) with a casting vessel (3) and a melt distributor (20), which distributes the metal melt (4) uniformly from a machine nozzle (7) among heated diecasting nozzles (40), wherein at least one nonreturn valve (48) is arranged between a sprue region (42) of the diecasting nozzles (40) and the casting vessel (3), wherein said at least one nonreturn valve (48) prevents the metal melt (4) from flowing back from the sprue region (42) in the direction of the casting vessel (3), such that said at least one nonreturn valve prevents retraction of the liquid metal melt from an upper diecasting nozzle and at the same time the flow of the liquid metal melt out of a lower diecasting nozzle due to gravity, characterized in that the at least one nonreturn valve (48) is respectively arranged between the sprue region (42) of at least one upper diecasting nozzle (40) and a final branch of melt runners (22) in the melt distributor (20) to each of the respective diecasting nozzles (40).

2. The diecasting nozzle system according to claim 1, wherein the diecasting nozzles (40) can be heated from inside and/or from outside in the region of a body of the diecasting nozzles (40) and comprises a sprue region (42) made of a material with a heat conductivity corresponding at least to the heat conductivity of the melt and/or can be heated separately.

3. 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).

4. The diecasting nozzle system according to claim 3, 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.

5. The diecasting nozzle system according to claim 4, wherein the thermal insulator is configured as an insulating ferrule (58) made of a material surrounding the sprue region (42) and having a low heat conductivity, 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 bodies of the diecasting nozzles (40) and the casting mold (30).

6. The diecasting nozzle system according to claim 4, 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).

7. The diecasting nozzle system according to claim 6, wherein a device that uses a CO.sub.2 cycle is provided for operation of the counter-heater.

8. The diecasting nozzle system according to claim 1, wherein a nozzle channel (41) 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) in the sprue region (42) of the diecasting nozzles (40), 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 a casting mold (30).

9. The diecasting nozzle system according to claim 1, wherein a temperature sensor (62) is arranged in the sprue region (42).

10. The diecasting nozzle system according to claim 1, wherein the nonreturn valve (48) is arranged in a nozzle channel (41) of the diecasting nozzles (40).

11. The diecasting nozzle system according to claim 1, wherein the nonreturn valve (48) is configured as a freely moving ball cooperating with a valve seat.

12. A diecasting method, which uses a diecasting nozzle system according to claim 1, characterized by the following method steps: fitting the permanently and uniformly heated diecasting nozzle (40) onto the casting mold (30); opening the 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 lower diecasting nozzles (40) in the melt distributor (20) by closing the nonreturn valves (48) in the region of the upper diecasting nozzles (40).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details, features and advantages of the invention become apparent from the following description of embodiment examples with reference to the associated drawings. In the drawings:

(2) FIG. 1 is a schematic illustration of a diecasting nozzle system according to the invention;

(3) FIG. 2 is a schematic cross-sectional illustration of a diecasting nozzle system according to the invention with two diecasting nozzles;

(4) FIG. 3 shows a further embodiment of the diecasting nozzle;

(5) FIG. 4 shows an embodiment of a detail of the diecasting nozzle according to the invention in the sprue region;

(6) FIG. 5 shows a further embodiment of the diecasting nozzle system according to the invention;

(7) FIG. 6 shows a further embodiment of the diecasting nozzle system according to the invention;

(8) FIG. 7 shows a further embodiment of the diecasting nozzle according to the invention and

(9) FIG. 8 shows a number of different sprue geometries.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) FIG. 1 schematically illustrates a hot-chamber system 1 comprising an embodiment of a diecasting nozzle system 10 according to the invention connected to a conventionally known hot-chamber diecasting machine 2. The hot-chamber diecasting machine 2 comprises a casting vessel 3, which contains melt 4. The latter is forced downward by a piston 5, which is driven by a piston drive 6, so that the melt 4 reaches the diecasting nozzle system 10 via a machine nozzle 7.

(11) In the diecasting nozzle system 10, the melt 4 is first forced into the melt distributor 20, which distributes the melt 4 among the individual diecasting nozzles 40. The diecasting nozzles 40 are directly connected to the static mold half 32 as a part of the casting mold 30. Located between the static mold half 32 and a moving mold half 34 is a cavity 36 in which the product is formed upon injection and solidification of the melt 4.

(12) FIG. 2 is a schematic cross-sectional illustration of an embodiment of a diecasting nozzle system 10 according to the invention with two diecasting nozzles 40, an upper one and a lower one. The diecasting nozzles 40 are inserted into the static mold half 32 of the casting mold 30 and are connected to the melt distributor 20. Two radial seats 24 and an axial seat 26, at which the diecasting nozzle 40 is supported, secure it in its position inside the casting mold 30. The sealing function of the front radial seat 24 may further also be improved by an additional sealing member, which is not depicted here. The function of this gap will be described in more detail in connection with FIG. 3.

(13) When the diecasting nozzle system 10 is in operation, the machine nozzle is positioned at a machine nozzle boss 12, via which it is fitted, and thus tightly connected, to the melt distributor 20 under mechanical pressure. Through this, the melt can flow from the casting vessel into a melt runner 22 of the melt distributor 20 and to the diecasting nozzles 40 and reach their respective nozzle channels 41. From the nozzle channel 41, the melt flows through the nonreturn valve 48, which opens in the flow direction, to the sprue region 42, where it is injected into the cavity 36. There, the product is formed upon solidification of the melt in the cavity. The melt may further also solidify in the sprue region 42 since the heat of the melt is dissipated via the casting mold 30 (which is oftentimes additionally cooled).

(14) In a particularly advantageous embodiment, the nonreturn valve is configured as a ball valve such that the ball has a low weight and performs a short stroke, for example one millimeter. This property enables the diecasting nozzle to perform its function according to the invention in a highly dynamic manner.

(15) For removal of the finished product, the moving mold half 34 is lifted off. In this process, the product is separated from the sprue region 42 of the diecasting nozzle 40. The separation of the product and the removal of the moving mold half 34 at the same time eliminates the dissipation of heat into the casting mold 30. The heat generated by a nozzle heater 43 and transferred to the diecasting nozzle 40 thereupon heats the sprue region 42 far enough for the melt solidified in the sprue region 42 to remelt. The nozzle heater 43 is in this case configured as a sleeve, for example made of brass or high-grade steel, which contains the heater and is fitted onto the body of the diecasting nozzle 40.

(16) As a result, the sprue region in the diecasting nozzles 40 is open for the ejection of the melt again. As long as only one diecasting nozzle 40 is present, the melt would be prevented from escaping by capillary forces or lack of pressure balance. However, as soon as multiple diecasting nozzles are present, in particular arranged in a stacked manner, air may enter the upper diecasting nozzle 40 through the sprue region 42. The entering air then causes a pressure balance in the melt runner 22 of the melt distributor 20, so that the melt may flow back from the upper diecasting nozzle 40 to the melt runner 22 and may escape from the lower diecasting nozzle 40 in an undesired manner, in particular in the case of an open casting mold 30. The same applies of course if the melt does not solidify in the sprue region but remains fluid.

(17) To prevent the melt from flowing out, a nonreturn valve 48 is provided according to the invention which prevents the melt from flowing back to the melt runner 22 of the melt distributor 20. As a result, due to the lack of pressure balance, melt cannot escape from the lower diecasting nozzle 40. Through this, even the sprue region 42 of the respectively lower nozzles remains practically sealed even without additional measures for closure such as a solidified melt plug or a nozzle needle.

(18) FIG. 3 is a schematic cross-sectional illustration of an embodiment of the diecasting nozzle 40 of the diecasting nozzle system 10 according to the invention including a detail view of the sprue region 42. The diecasting nozzle 40 is coupled to the melt distributor 20, so that its melt runner 22 is in communication with the nozzle channel 41. Further, the nonreturn valve 48, which is schematically illustrated here, is advantageously arranged inside the nozzle channel 41. However, it might just as well be arranged at any position in the depicted section of the melt runner 22.

(19) Further shown are the nozzle heater 43 and (only in the detail view) a part of the static mold half 32, against which rests the diecasting nozzle 40. To avoid heat dissipation from the diecasting nozzle 40 to the static mold half 32 via the resting support in the sprue region 42, i.e. the radial seat 24, a thermal insulator is provided. In the depicted example, said insulator consists in an air space 58, which surrounds a substantial part of the diecasting nozzle 40, and in particular in a sprue insulator 50. The sprue insulator 50 is arranged directly in the sprue region 42. It consists of a hollow space into which air, some other gas or an insulating material has been introduced. Moreover, provision is made for the sprue region to be fabricated of a different material having a reduced heat conductivity, for example a ceramic material. The sprue insulator 50 may be formed by joining parts configured to define the hollow space via a form lock or an adhesive connection.

(20) The sprue insulator 50 particularly effectively prevents a large portion of the heat from being dissipated via the radial seat 24. This enables heating of the sprue region 42 and melting of melt solidified there via the existing nozzle heater 43 without requiring arrangement of an additional heater in the sprue region 42. However, such an alternative solution, in which a separate nozzle heater is provided for the sprue region, is also within the scope of the invention.

(21) Dotted lines with arrows in the detail view further indicate the path of the melt flow in the final section of the nozzle channel 41 and to the sprue region 42. In the depicted embodiment example, the sprue region 42 has an annular sprue geometry. The latter is formed by the melt runner 41 near the sprue region 42 having a central duct 61 that passes the melt to the outside and into a cylindrical gap, which results in the annular sprue geometry. Further advantageous sprue geometries are shown in FIG. 8.

(22) FIG. 4 is a schematic cross-sectional illustration of an embodiment of a detail of the diecasting nozzle 40 according to the invention in the sprue region 42. As in FIG. 3, the melt flow in the nozzle channel 41 is indicated here as well.

(23) An important feature of the diecasting nozzle 40 according to the invention is shown in the sprue region 42. The latter comprises a separation edge 60, which may be provided on one side or on both sides, i.e. on the inner side at the central duct 61 and/or on the outer side in the lower section of the melt duct 41 as a respective circumferential protrusion. Shown is a two-sided configuration in the inner and outer region, wherein the separation edge 60 creates a reduced cross-section between the product, which consists of the solidified melt, and the “frozen” sprue region, i.e. the melt plug formed in said region. Said reduced cross-section forms a breaking point at which the product separates from the melt plug in the sprue region in a defined manner and thus provides for the creation of a proper sprue on the product that does not require postprocessing.

(24) FIG. 5 is a schematic illustration of an embodiment of the diecasting nozzle system 10 according to the invention including, similar to the illustration of FIG. 3, a detail view of the sprue region 42, which in addition to the static mold half 32 also shows the moving mold half 34 and the cavity 36.

(25) There are, however, a number of differences compared to the embodiment example of FIG. 3. These relate to the environment of the sprue region 42 and the nozzle heater 44. The latter is embedded in a circumferential groove in the body of the diecasting nozzle 40.

(26) At the sprue region 42, a part of the static mold half 32 is depicted, which is formed such that an insulating air space 58 forms between said fixed mold half and the diecasting nozzle 40. Also arranged in this region is a temperature sensor 62, which is connected via a lead 63. In the detail view, the channel for said lead may also be used for a supply line of the heater.

(27) FIG. 6 shows a schematic cross-sectional illustration, including a detail view, of an embodiment of the diecasting nozzle system 10 according to the invention, which differs from those shown in FIGS. 3 and 5 with respect to the type of heating and the design of the sprue region 42. To improve the thermal insulation from the static mold half 32, the sprue region 42 is provided with an insulating ferrule 59, which is for example made of a titanium alloy. Said insulation ferrule is arranged at the sprue region 42 and surrounds the latter in the region of the radial seat 24.

(28) In the illustrated embodiment example, the diecasting nozzle 40 is heated via a printed nozzle heater 45, which is applied to the body of the diecasting nozzle 40 in a helical configuration and is protected by a moving protective sleeve.

(29) FIG. 7 is a schematic cross-sectional illustration of a further embodiment of a diecasting nozzle 40′ according to the invention, which substantially differs from the embodiments described above. It includes a nozzle heater 46 configured as an internal heating rod. The nozzle heater 46 is surrounded by the nozzle channel 41, which thereby has the shape of a hollow cylinder. Through this, the heat can easily be guided directly to the sprue region 42 without requiring any particular thermal insulation measures to counteract the heat dissipation. This embodiment is particularly advantageous for the use of melts with a melting temperature of more than 600° C. or for multi gating, in which melt is supplied from one diecasting nozzle to multiple cavities located closely adjacent to one another.

(30) The hollow-cylindrical nozzle channel 41 has no nonreturn valve since the latter needs to be arranged in the melt runner of the melt distributor when employing such a diecasting nozzle 40′.

(31) The nozzle channel 41 connects to the sprue region 42, which in the present embodiment example has a dot-shaped configuration.

(32) Further sprue shapes are illustrated in FIG. 8.

(33) View a) shows a sprue geometry of a multi-path nozzle, which can be used to fill a multi-cavity mold. In this case, the melt is then injected not only into one cavity but into multiple cavities arranged closely adjacent to one another, so that multiple parts can be fabricated with one nozzle.

(34) View b) shows a sprue geometry that results from a cross-section of FIGS. 2 to 6 and is formed as an annular sprue with a large cross-section for short casting times. The tip arranged inside the ring, i.e. the central duct 61 (cf. FIGS. 3 and 4) provides for heat transfer from the heated nozzle body into the sprue region and to this end is made of a material having a particularly high heat conductivity, for example a suitable alloy. Through this, any melt that may have solidified in the sprue region upon separation of the product and thus elimination of the heat sink is quickly remelted, so that a new diecasting cycle for fabrication of a further product can be started. This can be additionally supported especially if the entire sprue region is made of said material having a particularly high heat conductivity.

(35) In view c) the annular sprue is supplemented by a dot-shaped sprue arranged centrally inside the ring, so that an even larger volumetric flow rate can be achieved for the melt. A dot-shaped sprue without the additional annular sprue may also be provided. Such a variant already results from the diecasting nozzle 40 illustrated in FIG. 7.

(36) Views d) to f) respectively show a sprue geometry that provides similar stability in the sprue region but offers a quicker injection of the melt into the cavity, particularly if the latter has a larger volume. This is achieved by grooves originating laterally from the annular sprue geometry so as to form a line, two crossed lines, or a star-shaped sprue geometry.

LIST OF REFERENCE NUMERALS

(37) 1 hot-chamber system 2 hot-chamber diecasting machine 3 casting vessel 4 melt 5 piston 6 piston drive 7 machine nozzle 10 diecasting nozzle system 12 machine nozzle boss 20 melt distributor 22 melt channel 24 radial seat 26 axial seat 30 casting mold 32 static mold half 34 moving mold half 36 cavity 36′ product 40, 40′ diecasting nozzle 41 nozzle channel 42 sprue region 43 nozzle heater (sleeve) 44 nozzle heater (circumferential groove) 45 nozzle heater (moving sleeve) 46 nozzle heater (internal heater) 48 nonreturn valve 50 sprue insulator 58 insulating space 59 insulating ferrule 60 separation edge 61 central duct 62 temperature sensor 63 lead