Patent Application
20200001355
This application claims benefit to European Patent Application No. EP 18 180 430.3, filed Jun. 28, 2018, which is incorporated by reference herein.
The invention relates to a method and a device for producing metals or metal alloys, to which solids are added, preferably light metals or light metal alloys for the casting of cast parts, preferably diecast parts
Methods for producing composite materials by adding particles in order to improve physical properties, such as mechanical strength, or to improve fatigue strength, are known from the prior art. The challenge when introducing the solids due to the high wetting angle, particularly in light metal melts, is also known.
The poor wetting behaviour of solids because of the high wetting angle, especially in the case of nonmetallic solids, in the melt, is equivalent to poor matrix binding, which makes it difficult to incorporate solids into a metal or metal alloy. Furthermore, such a process is very elaborate.
U.S. Pat. No. 7,509,993 B1 discloses a method in which the particles are added while the casting melt is still in the melting furnace in the liquid state. This, however, entails the disadvantage that there is not a continuous process up to the mould filling, but rather in each case only one furnace charge can respectively be cast, which then also respectively has a different ratio of fibres to melt per charge. There is furthermore the possibility of sedimentation since scarcely any mixing takes place during the casting of the casting melt.
In an embodiment, the present invention provides a method for producing metals or metal alloys. The method includes melting, by a melting apparatus, a metal or a metal alloy to produce a casting melt, transporting, by a feed line, the casting melt to casting moulds to be filled, adding, during the transporting of the casting melt by the feed line, solids to the casting melt, and mixing the casting melt with the added solids in a mixing zone during the transporting of the casting melt by the feed line.
The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. All features described and/or illustrated herein can be used alone or combined in different combinations in embodiments of the invention. The features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:
The FIGURE shows a device according to the invention for producing metals or metal alloys to which solids are added.
The invention relates to a method and a device for producing metals or metal alloys, to which solids are added, preferably light metals or light metal alloys for the casting of cast parts, preferably diecast parts, the method including the steps of melting a metal or a metal alloy by means of a melting apparatus, transporting casting melt by means of a feed line to casting moulds to be filled, and adding solids to the casting melt during the transport of the casting melt in the feed line.
Embodiments of the invention provide a method and an associated device, which make it possible to incorporate solids into a metal or a metal alloy while achieving good wetting of the solids and homogeneous mixing without cluster formation, as well as to ensure a continuous production process.
Embodiments of the invention provide for added solids and the casting melt to be mixed in a mixing zone, preferably by means of energy input, during transport, where the mixer is arranged on the feed line.
The method according to the invention relates to a method for producing metals or metal alloys, to which solids are added, preferably light metals or light metal alloys for the casting of cast parts, preferably diecast parts.
First the metal or metal alloy is melted until the metal or the metal alloy is converted into the liquid state and is present as a casting melt.
The casting melt is transported by means of a feed line to the casting moulds to be filled, which may preferably be carried out by means of a gradient of the feed line and/or by means of a pump. An electromagnetic pump is especially preferred for the feeding of the casting melt.
In order to add solids into the casting melt, the solids are introduced into the casting melt by means of a dosing system during the delivery in the feed line. In order to ensure homogeneous mixing and optimal wetting of the solids, the casting melt is mixed with the solids during the transport, or the delivery, in the feed line in a mixing zone, preferably by means of energy input, in which case the mixing zone may also be arranged directly in the region of the dosing system for introducing of the solids.
It is advantageous for the mixing to be carried out during and/or after the addition of the solids. By optical mixing, cluster formation of the solids is prevented and the binding and the wetting behaviour of the solids with respect to the casting melt are improved.
One preferred embodiment consists in the energy input for the mixing being carried out in at least one mixing zone by means of an ultrasound sonotrode. This improves the binding of the solids to the casting melt in that agglomerations of solids which have been formed are broken up by the ultrasound by means of the energy and pulses delivered, and the individual solids can thereby bind better to the casting melt and the wetting angle between the solid and the casting melt is reduced, which in turn contributes to improvement of the binding.
As another advantage of the energy input, preferably by means of ultrasound, the oxide layer which is located on the casting melt and prevents the entry of solids because of the surface tension, is removed, so that the solids can penetrate better into the casting melt.
It has been found advantageous for the supply of the casting melt in the feed line to be carried out continuously. In this way, a continuous and ongoing process, as well as a high efficiency, can be ensured.
Preferably, the solids are formed as fibres and/or particles, fibres having an elongate shape and particles being shaped more spherically or in the form of flakes.
It is advantageous for the fibres or particles to come from the group carbon fibres, aluminium oxides, basalt, silicon carbide, aramid, metal fibres, coated fibres and/or derivatives thereof. From tests, it has been found that these fibres and flakes or particles have good thermal stability and do not anneal in the highly heated casting melt.
One preferred embodiment consists in the feed line being thermally regulated. By the possibility of different thermal regulation over the feed line, an influence can be exerted on the states of the casting melt. This means, for example, that the feed line can be cooled, so that the casting melt is actively cooled and the state of the casting melt is semisolid, or lies in the semisolid range of a metal or a metal alloy. Of course, there is also the possibility of heating the feed line in order to bring the casting melt into the liquid state or keep it in this state.
It is advantageous for the casting melt to be cooled during the transport in the feed line, preferably until the casting melt has a semisolid state. The semisolid state makes it possible for the solids to be kneaded in, which in turn achieves an improvement in the binding between the solids and the alloy. It is advantageous for the temperature to be kept at a certain temperature level in order to have the same state of the casting melt over a particular range, so that the solids can be correspondingly introduced or the binding between the solids and the metal or metal alloy is improved, for example by means of kneading or applying ultrasound.
The invention is distinguished by a further configuration in which the solids are kneaded into the casting melt in the semisolid state in a mixing zone. Any kneading is preferably carried out in a further mixing zone, which is preferably likewise arranged on the feed line.
The device according to the invention for producing metals or metal alloys, to which solids are added, preferably light metals or light metal alloys for the casting of cast parts, preferably diecast parts, contains a melting apparatus in which the metal or the metal alloy is melted, a furnace preferably being used for this. For delivery or transport of the casting melt, the device contains a feed line. The dosing system of the device according to the invention is used to add solids into the casting melt, the dosing system being connected to the feed line. The device according to the invention contains at least one mixer for homogeneous mixing of the casting melt, the mixer being arranged on the feed line and the mixing of the casting melt being carried out during the transport or delivery.
It is advantageous for the mixer to be configured as an ultrasound sonotrode. By mixing of the solids in the preferably liquid casting melt by means of ultrasound, the binding, as mentioned above for different reasons, between the casting melt and the solid is improved.
It has been found advantageous for a pump for delivering the casting melt, preferably an electromagnetic pump, to be arranged on the feed line. This ensures continuous and controllable transport or delivery of the casting melt.
It has been found to be a preferred embodiment when the feed line comprises a bypass line, the bypass line permitting a plurality of passes of the casting melt through the introduction and mixing zone. This allows high flexibility of the quantity of solids added, or to be added, as well as the mixing. Preferably, the bypass line can be thermally regulated.
The dosing system preferably comprises an injector for introducing the solids into the casting melt. This ensures continuous introduction of solids into the casting melt.
It is advantageous for the feed line to comprise a tube constriction in the region of the dosing system. This permits a lower pressure in the narrower region, so that the solids which are present in the dosing system are entrained by suction.
The metal or metal alloy according to the invention is preferably used for the production of cast parts, in particular diecast parts, the cast parts preferably being used as vehicle parts. Of course, other fields of application may be envisaged. The composition of the corresponding metal, or of an alloy, is to be marked to the application and correspondingly provided with solids suitable therefor.
All configuration possibilities may be combined freely with one another, and the features of the method as well as of the device and the use specifications may be combined freely with one another.
The drawing represented in the FIGURE shows a device 1 according to the invention for producing metals or metal alloys to which solids are added. The device 1 comprises a melting apparatus 2, preferably a furnace, for melting metals and metal alloys. The casting melt thereby obtained is transported by means of a feed line 3 to the casting moulds 9 to be filled.
Preferably, in order to deliver the casting melt in the feed line 3, a pump 11 is used which ensures that a constant and preferably continuous flow of the casting melt flows through the feed line 3. Arranged on the feed line 3, or connected thereto, there is a dosing system 4 which introduces the solids, preferably particles or fibres, into the casting melt. In order to mix the solids with the casting melt, at least one mixer 5 is arranged on the feed line 3, in which case a plurality of mixers 5 may also be arranged at different positions of the feed line 3. Preferably, there is already a mixer 5 in the region of the dosing system 4, which is preferably configured as an ultrasound sonotrode and which ensures mixing of the solids in the preferably still liquid casting melt. As an alternative, a further mixing zone 6 with a corresponding mixer 5 may be arranged on the feed line 3, which again mixes the casting melt, preferably when the casting melt is in a semisolid state and is kneaded by means of the mixer 5, which ensures good binding of the solids to the casting melt. In order to ensure an optimal state of the casting melt, the feed line 3 can be correspondingly thermally regulated, whether by heating or by cooling, and this may correspondingly be applied individually. As one possible embodiment, a bypass line 8 is arranged on the feed line 3, which permits repeated passing of the casting melt through the introduction and mixing zone 7 on the feed line 3, and the casting melt is thus correspondingly provided with solids until the casting melt has the desired composition and is sufficiently mixed, and it is subsequently introduced into the casting moulds 9.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18 180 430.3 | Jun 2018 | EP | regional |
