Hot chamber die casting casting vessel

Abstract

Casting vessel (1) for a hot-chamber die-casting plant, the casting vessel (1) comprising a casting chamber (2) configured to interact with a casting piston provided for changing the volume of the casting chamber (2), as well as an inlet (3) for liquid melt opening into the casting chamber (2), and an outlet (3) located in the bottom region of the casting chamber (2), through which outlet the melt can be discharged under pressure, characterized in that the casting vessel (1) is designed in several parts such that a parting plane is provided which runs at least through the casting chamber (2) in the longitudinal direction (L), through which parting plane the melt-carrying inner side of the casting chamber (2) can be exposed when the casting vessel (1) is disassembled.

Description

Introduction

[0001] The invention relates to the technical field of hot-chamber die casting. In particular, the invention relates to a casting container for use in a hot-chamber die casting system suitable for processing aluminum alloys. State of the art and disadvantages

[0002] Die casting processes have long been state-of-the-art. In these processes, a molten metal is poured under high pressure into a permanent mold, where it cools and solidifies until it can be ejected while maintaining the desired geometry.

[0003] A distinction is made, among other things, between cold-chamber and hot-chamber die casting processes. In the latter, a crucible-like furnace is used to prepare the molten melt. This contains the vertical casting vessel with the casting chamber and casting piston. The casting chamber refills with new melt after each cycle; the casting piston successively reduces the internal volume of the casting chamber, thus conveying the melt from the casting vessel into the mold. When the casting piston is retracted, the casting chamber refills itself automatically via a filling hole, allowing the casting cycle to begin again.

[0004] Due to the permanently high temperature of the casting container and casting piston, the process is currently only suitable for metals and alloys with less corrosive properties and lower melting temperatures, such as zinc, magnesium, tin or lead.

[0005] For alloys with a higher melting point and more corrosive properties, such as aluminum in particular, the so-called cold chamber die casting process has typically been used; in this process, the casting set is arranged outside the metallic melt.

[0006] Various casting vessel designs are known for use in hot-chamber die casting. One-piece casting vessels made of cast iron, for example, are cost-effective but require complex maintenance, particularly for the barrel sleeve. However, this does not allow for long service life due to the highly corrosive properties of aluminum. Multi-piece casting vessels enable the use of casting chambers made of alternative materials, which makes it possible to use more wear-resistant materials for the piston running surface. In this case, a corresponding cylinder is inserted into the bore of the casting chamber as a wear bushing. Although ceramic materials are generally suitable as a material for such wear bushings, as is known, for example, from the document DE 1110 828 B, by shielding the melt from the metallic component surfaces, contamination of the melt itself is also prevented.However, the high compressive forces and different thermal expansion coefficients lead to mechanical stresses, even leading to the detachment or breakage of the bushing. Here, too, a simple replacement of the wear bushing is hardly possible due to the force-locking mechanical connection (shrink-fit).

[0007] A design based on a special mounting and self-centering mechanism for the pressure cylinder and casting piston, which is intended to compensate for the different thermal expansion coefficients of metal and ceramic, is known from document DE 2414118 A1. A casting set with an improved sealing and guiding arrangement for the casting piston is described in document DE 69603605 T2. Document DE 69703604 T2 proposes the use of a multi-part, ceramic sprue system. Despite some efforts in the state of the art, no system for hot-chamber die casting of aluminum alloys is currently available that can be provided at a reasonable cost and also allows for sufficiently long service life / shot counts for cost-effectiveness.Although promising ceramic-based materials are available, they are not suitable for surface coatings of the melt-conducting areas, especially in the case of long bores such as those required in a casting vessel. Task of the invention and solution

[0008] The invention is therefore based on the object of providing a device that avoids the disadvantages of the prior art. Accordingly, the invention is intended to provide a casting chamber that is suitable for hot-chamber die casting of, for example, aluminum and aluminum alloys, can be provided at a reasonable cost, and also allows for sufficiently long service lives / shot counts for cost-effectiveness.

[0009] The object is achieved by a device according to claim 1. Advantageous embodiments can be found in the dependent subclaims, the following description and the figures. Description

[0010] The casting container according to the invention and advantageous embodiments thereof are first described below. This is followed by a description of the manufacture of a casting container and its maintenance.

[0011] The casting container is intended for use in a hot-chamber die-casting system, which is particularly intended for casting aluminum and its alloys.

[0012] The casting vessel comprises a casting chamber configured to interact with a casting piston designed to vary the volume of the casting chamber. It further comprises an inlet for liquid melt leading into the casting chamber and an outlet located in the bottom region of the casting chamber through which the melt can be discharged under pressure. Such casting chambers are already well known in the art and suffer from the disadvantages described above.

[0013] The casting container according to the invention is characterized in that it is designed in several parts in such a way that a parting plane is provided which runs at least through the casting chamber in the longitudinal direction and through which the melt-carrying inner side of the casting chamber can be exposed in the disassembled state of the casting container.

[0014] "Multi-part" here means that the casting vessel is not designed as a single piece, or is essentially made up of several pieces, whereby additions such as a barrel sleeve or a gooseneck (see below) are not counted. This multi-part design provides one or more parting or cutting planes that are parallel to one another, perpendicular, or at a different angle to one another. It is important that one parting plane is positioned such that it runs lengthwise through the casting chamber, thereby physically dividing it into two "halves" that are (preferably) the same size, but can also have different sizes or shapes. There can also be several such parting planes, so that the casting chamber is divided into a corresponding number of segments.

[0015] Due to this "separation" of the casting chamber along or parallel to its longitudinal axis, the interior of the casting chamber is "exposed" (when the casting chamber is disassembled), i.e., freely accessible. "Freely accessible" here means that, in addition to the openings typically known from the prior art at the inlet and / or outlet of the casting chamber, there are additional access options, namely those that run in a direction perpendicular to the longitudinal axis of the casting chamber.

[0016] The effect of such "exposed" accessibility is that said melt-conducting surfaces can be coated using processes that would not be applicable to a non-separated casting chamber, making them more durable against a highly reactive melt such as aluminum. This applies in particular to CVD and PVD (chemical / physical vapor deposition) processes, which, while capable of producing tribologically advantageous coatings, are unsuitable for coating deeper holes and openings. By "exposing" or "opening" the casting chamber, its interiors can also be advantageously coated using, for example, CVD / PVD processes.

[0017] The invention thus avoids the disadvantages known from the prior art.

[0018] The invention provides a casting chamber which is suitable for hot chamber die casting of, for example, aluminum and aluminum alloys, can be provided at a reasonable cost, and also allows sufficiently long service lives / number of shots for economic efficiency.

[0019] Various embodiments of the invention are described in more detail below.

[0020] According to one embodiment, the casting vessel is designed in several parts such that the casting chamber is divided into two hollow cylindrical segments. It is clear that the term "hollow cylindrical segments" only approximately describes the shape of the casting chamber; what is meant is that the casting chamber can be divided into two halves, with the dividing plane running approximately parallel to or along the longitudinal axis of the casting chamber. The longitudinal axis is the axis along which the casting piston moves to pressurize the melt in the casting chamber and expel it through the outlet.

[0021] Preferably, the parting plane runs exactly along the longitudinal axis, so that two substantially equal halves or half-shells are present, which together form the casting chamber.

[0022] According to a preferred embodiment, the entire casting vessel comprises two halves, by which the casting chamber is divided into said two hollow cylinder segments. In other words, not only is the casting chamber itself divided by the parting plane, but the same continues through the entire casting vessel, so that the latter - together with the casting chamber - exists as two half-shells, in the approximate centers of which the (semi-cylindrical) cavities of the respective casting chamber halves are arranged. While the parting plane continues to run through the longitudinal axis of the casting chamber, very different angles are possible, by which the parting plane is rotated towards the exit, for example. An angle of 0° means that the parting plane also runs through the exit. At an angle of 90°, the exit is in the middle of one of the two half-shells.

[0023] According to a further preferred embodiment, the casting container further comprises a gooseneck as an outlet, as is also known in principle from the prior art. However, according to the invention, the inside of the gooseneck is also "exposed" when the casting container is disassembled due to the multi-part design of the casting container. For example, it is conceivable to have a further parting plane positioned such that the longitudinal bore through the gooseneck is exposed, which brings with it the advantages described above with regard to coatability. For example, the area in which the gooseneck is located can be split in the middle so that one shell remains on the main body of the casting container (or is provided by it), and the other shell is provided by a removable molded part that can be attached to the main body.

[0024] However, it is preferred that the parting plane also runs lengthwise through the gooseneck. This means that the entire casting vessel is divided into two halves by one and the same parting plane, so that both the casting chamber and the interior of the gooseneck are "exposed" when the casting chamber is disassembled. Such a construction is particularly simple and offers the possibility of simultaneously coating both the casting chamber and the interior of the gooseneck. The same applies to all other access points (e.g. gooseneck inlet and outlet, filling bore of the casting chamber), provided they are passed through by a parting plane. This enables particularly economical coating of the melt-carrying surfaces of the casting vessel.

[0025] According to another embodiment, which can be combined with the embodiments described above, the casting chamber comprises an insert made of a ceramic material as a barrel sleeve inserted into the casting chamber. The advantage of such a barrel sleeve is its ability to be manufactured from a tribologically particularly advantageous material, such as ceramic. Such barrel sleeves are already known from the prior art; however, due to their high mechanical susceptibility to fracture and the fact that they have an expansion coefficient that differs significantly from that of the surrounding metallic material, installation in a conventional casting chamber is complex, as it must be achieved by shrinking into the casting vessel bore or by means of a very precise, form-fitting bearing. Disassembly of such a barrel sleeve is equally difficult, assuming this is to be done non-destructively.

[0026] In contrast, the inventive separation of the casting chamber into two or more halves or segments allows the barrel sleeve to be inserted while the casting chamber is cold, as well as stored in a material-appropriate manner. Thus, the inventive solution also offers the advantage of using ceramic barrel sleeves while avoiding the disadvantages known from the prior art when assembling (and disassembling) them from conventional casting chambers.

[0027] Preferably, the material of said barrel sleeve is a nitride, carbide, or oxide ceramic of high density and hardness. Although such ceramics are generally known from the state of the art, their use as barrel sleeves for casting chambers has not been possible until now.

[0028] A particularly preferred ceramic material is a glass ceramic, for example the material marketed by Schott under the trade name ZERODUR® or ZERODUR® K20. Tests have shown that this material can be used to provide barrel sleeves and casting pistons with particularly advantageous properties. The inherent properties of the material, which make installation in conventional casting chambers difficult, such as, in particular, high fracture sensitivity, are practically eliminated in the casting vessel according to the invention. It is particularly advantageous if the barrel sleeve is made of a ceramic material and the casting piston is made of a glass ceramic or comprises the corresponding material.

[0029] According to a further embodiment, the bottom of the casting chamber is formed by a separate end piece. Such an end piece or such a "plug" makes it easy to provide a highly sealed casting chamber, even if this is a divided casting chamber according to the invention. The end piece can also have a transverse bore that opens into the inlet of the gooseneck, if one is present. Since the end piece is relatively short and, in particular, has an internal recess a few centimeters deep, this recess can be easily coated using the methods described above, since this recess also comes into permanent contact with the melt during operation.

[0030] The casting chamber is therefore initially open at both ends and is closed by the end piece at the lower end during operation. This also applies if a barrel sleeve is used as the inner lining of the casting chamber.

[0031] Particularly preferably, at least the surfaces intended for contact with the liquid melt are coated with a layer of aluminum chromium nitride (AlCrN). This material can be applied using the CVD / PVD process mentioned above and exhibits advantageous tribological properties for the present application. Such a material has not previously been used in the field of coating hot-chamber die-casting vessels, as the coating process suitable for applying this material is not suitable for coating long bores.

[0032] In addition, the production of a casting vessel according to the preceding description will now be explained. After the parts of the casting vessel have been prepared, at least those surfaces intended for contact with the liquid melt are coated using a coating process, such as, in particular, a PVD or CVD process, in such a way that said surfaces become resistant to corrosion caused by the melt, whereupon the parts of the casting vessel are joined together (detachably or permanently). In other words, based on the multi-part construction and the associated significantly improved accessibility of the surfaces to be coated, these are coated using a process that can only be used to coat easily accessible surfaces. This applies in particular to CVD and PVD processes.

[0033] The production provides a casting container which is suitable for processing aluminium alloys in the context of hot chamber die casting.

[0034] Particularly preferably, the coating consists of aluminum chromium nitride or comprises this material. To avoid repetition, reference is made to the above explanations.

[0035] If a barrel sleeve made of a ceramic material of the type described above is available, it can advantageously be inserted into the casting chamber (or halves) before at least the individual parts constituting the casting chamber are assembled. This effectively circumvents the problems known from the prior art when installing such a barrel sleeve. Reference is also made to the above explanations for further details.

[0036] Finally, the maintenance of a casting vessel of the type according to the invention with a ceramic barrel sleeve is also described, whereby it is clear that the casting vessel must be capable of being disassembled accordingly. After cooling, the vessel is first disassembled into its individual parts so that the corresponding surfaces are at least exposed to the casting chamber. The barrel sleeve made of one ceramic material can then be replaced with another, and the individual parts can subsequently be reassembled.

[0037] The coating can also be renewed in the same way; here too, the easy disassembly allows quick access to the relevant surfaces for repeated coating using the methods described above. Character description

[0038] The invention is explained below by way of example with reference to figures. Fig. 1 a perspective view of a casting container of the type according to the invention with a casting chamber open on both sides; Fig. 2 a perspective view of one half of a casting container according to the invention; Fig. 3 a view similar to the construction from Fig. 2, but intended for use with a ceramic insert; Fig. 4 the same view, supplemented by a ceramic sleeve and an end piece.

[0039] In the Fig. Figure 1 shows a perspective view of a casting container 1 of the type according to the invention with a casting chamber 2 open on both sides. As can be seen from the body edges created by the dividing plane T1 indicated by dash-dotted lines, the casting container 1 is divided into two halves 1A, 1B. These are similar to each other, but not identical. The casting chamber 2 is located in the center of the two halves 1A, 1B.

[0040] Also shown are alternative parting planes T2 and T3, shown in dotted lines. Parting plane T2 also runs centrally through the casting chamber 2, but is rotated by 90° relative to parting plane T1. Nevertheless, such a parting plane T2 also results in the inventive exposure of the inner sides of the casting chamber 2.

[0041] Also shown is a further parting plane T3, which leads to the exposure of further melt-carrying parts of the casting vessel 1, as can be seen from the following figure.

[0042] In the Fig. Figure 2 shows a perspective view of one half 1A of a casting vessel. The parting plane T1 (not shown here) runs along the surface facing the viewer in the image. Since no material is cut here, no hatching is shown. Clearly visible is half of the casting chamber 2, which has the shape of a cylindrical segment. For reasons of clarity, known fasteners (e.g., holes, screws, etc.) intended for connecting two halves have been omitted.

[0043] Inlets 3 lead into the casting chamber 2. Melt (not shown) enters the casting chamber 2 through these inlets when the casting piston (not shown) retracts. Outlet 4 is located in the bottom area of ​​the casting chamber 2. The melt, pressurized by the casting piston, can exit the casting chamber 2 through this outlet.

[0044] As can be seen, due to the continuous parting plane T1 in the longitudinal direction L of the casting chamber 2, the melt-carrying inside of the casting chamber 2 is exposed in the disassembled state of the casting vessel 1, i.e. freely accessible; accessibility is no longer limited to the Fig. 1. Thus, the inner surface can be provided with a tribologically advantageous coating at desired locations, whereby processes such as CVD and PVD processes can now also be used, which would not lead to satisfactory coating results without said exposure.

[0045] The embodiment shown also includes a gooseneck 5, into which the outlet 4 of the casting chamber 2 opens. Due to the multi-part nature of the casting container 1 in the disassembled state, the inside of the gooseneck 5 is also exposed and can therefore also be advantageously coated.

[0046] Also shown are the two alternative parting planes T2 and T3. Parting plane T2 intersects the casting chamber 2, and the parallel parting plane T3 intersects the gooseneck 5 in its longitudinal direction. It is clear that in this case, parting plane T1 can be omitted, resulting in three (rather than six) main components, which, when combined, form the casting chamber 1 as shown in FIG. Fig. 1, but with correspondingly different separation planes T2, T3.

[0047] Fig. 3 and Fig. 4 show a view similar to the construction in Fig. 2, but intended for use with a ceramic insert as a barrel sleeve 6 for the casting piston (not shown). Fig. 3 shows the fit 7 for the barrel sleeve 6, as well as a shoulder intended as a counter-hold 8.

[0048] In Fig. 4, the barrel sleeve 6 is shown, with its upper end (right in the picture) resting against the counter-hold 8. At the other, lower end (left in the picture) it rests against an end piece 9, which forms the bottom of the casting chamber 2; such an end piece 9 is also suitable for installation in the embodiments according to Fig. 1, Fig. 2 and Fig. 3. The end piece 9 has a transverse bore (concealed) so that the melt can flow from the casting chamber 2 into the outlet 4 and the gooseneck 5. Also visible are holes 10 in the barrel sleeve 6, which are aligned with the inlets 3 to allow the melt to flow into the casting chamber.

[0049] As can be seen, the assembly and disassembly of the barrel sleeve 6 is very simple, as it is not Fig.1, but can be inserted into the split casting chamber before the other half is connected. The heating required for shrink-fitting is completely eliminated, and installation and removal can be performed in a material-friendly and non-destructive manner. List of reference symbols 1 watering container 1A,1B half 2 casting chamber 3 Access 4 Exit 5 gooseneck 6 Barrel sleeve 7 Fit 8 Counterhold 9 End piece 10 holes L Longitudinal axis, longitudinal direction T parting line QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 1110 828 B

[0006] DE 2414118 A1

[0007] DE 69603605 T2

[0007] DE 69703604 T2

[0007]

Claims

[1] Casting container (1) for a hot-chamber die-casting plant, the casting container (1) comprising a casting chamber (2) designed to interact with a casting piston provided for changing the volume of the casting chamber (2), as well as an inlet (3) for liquid melt opening into the casting chamber (2), and an outlet (3) located in the bottom region of the casting chamber (2) through which the melt can be discharged under pressure, characterized by that the casting container (1) is designed in several parts in such a way that a parting plane is provided which runs through at least the casting chamber (2) in the longitudinal direction (L), through which the melt-carrying inside of the casting chamber (2) can be exposed when the casting container (1) is disassembled. [2] Casting container (1) according to claim 1, wherein the same is designed in several parts such that the casting chamber (2) is divided into two hollow cylinder segments. [3] Casting container (1) according to claim 2, wherein the entire casting container (1) comprises two halves (1A, 1B) by which the casting chamber (2) is divided into two hollow cylinder segments. [4] Casting container (1) according to one of the preceding claims, further comprising a gooseneck (5) as the outlet (4), wherein the inside of the gooseneck (5) is also exposed due to the multi-part nature of the casting container (1) in the disassembled state of the casting container (1). [5] Pouring container (1) according to claim 4, wherein the parting plane also passes through the gooseneck (5) in its longitudinal direction. [6] Casting container (1) according to one of the preceding claims, further comprising an insert made of a ceramic material as a barrel sleeve (6) inserted into the casting chamber. [7] Casting container (1) according to claim 6, wherein the material is a nitridic, carbide or oxide ceramic of high density and hardness. [8] Casting container (1) according to claim 6, wherein the ceramic material is a glass ceramic. [9] Casting container (1) according to one of the preceding claims, wherein the bottom of the casting chamber (2) is formed by a separate end piece (9). [10] Casting container (1) according to one of the preceding claims, wherein at least the surfaces intended for contact with the liquid melt are provided with a layer of aluminum chromium nitride.

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