Pressure die casting process and apparatus for carrying out the process

Abstract

The invention relates to a die-casting method and a corresponding device for a metal, in particular a light metal and its alloys, comprising the following steps: melting the metal, introducing the metal under pressure into a die-casting mold, solidifying the metal in the die-casting mold, wherein solid particles are added to the molten metal.

Description

[0001] The invention relates to a die-casting method and a device for carrying out the method according to the preambles of claims 1 and 13.

[0002] Die casting processes are well known. In the die casting process, liquid melt is pressed into a die casting mold under pressure of, for example, 150 to 1200 bar and at high filling speeds of up to 540 km / h. Alloys, especially light metal alloys with a low melting point, are typically used.

[0003] The production of die-cast parts requires a large amount of primary energy to melt the metal. Material costs are also considerable. Furthermore, the die-casting molds are subject to significant wear, particularly due to thermal shock caused by the high melt temperatures.

[0004] Based on this, the present invention is based on the object of providing a die-casting process and a device for carrying out such a process, which enable more sustainable production while at the same time improving the quality of the castings.

[0005] According to the invention, this object is achieved by the features of independent claims 1 and 13.

[0006] According to the invention, a die-casting process produces a cast part made of metal, i.e., aluminum or an aluminum alloy. Suitable metals for this purpose are light metals and their alloys, such as aluminum alloys, in particular the aluminum alloys most commonly used in die-casting, EN AC-46000 / EN AC-AlSi9Cu3(Fe). Also other aluminum alloys such as EN AC-46200 / EN AC-Al Si8Cu3, EN AC-46600 / EN AC-Al Si7Cu2, EN AC-47000 / EN AC-AlSi12(Cu), EN AC-47100 / EN AC-AlSi12Cu1(Fe), EN AC-42100 / EN AC-AlSi7Mg0.3, EN AC-42200 / EN AC-AlSi7Mg0.6, EN AC-43000 / EN AC-AlSi10Mg(a), EN AC-43200 / EN AC-Al Si10Mg(Cu), EN AC-43300 / EN AC-AlSi9Mg, EN AC-43400 / EN AC-AlSi10Mg(Fe), EN AC-43500 / EN AC-AlSi10MnMg, EN AC-44200 / EN AC-AlSi12(a), EN AC-44300 / EN AC-AlSi12(Fe)(a), EN AC-45000 / EN AC-AlSi6Cu4 are suitable because they have a relatively low melting point, e.g. in a range of 580°C to 660°C.The alloy designations used in this application correspond to the European standard and are specified numerically / chemically (EN = European standard; AC = aluminum casting). In this application, "metal" refers to the metal or metal alloy, such as aluminum or an aluminum alloy.

[0007] According to the invention, the metal is melted in a known manner, and then, before the metal is introduced into a die-casting mold under pressure, solid particles are added (i.e., after, not in, a device for melting the metal). The solid components are therefore not added during the melting of the alloy. The liquid and solid components are only combined directly at the device, i.e., the die-casting machine.

[0008] The addition of solid particles, especially metallic solid particles, brings the following advantages: By adding additional solid material to the melt, less metal needs to be melted, resulting in a significant saving in thermal energy, which leads to a significant reduction in production costs.

[0009] Furthermore, the addition of solid particles can lower the temperature of the melt, resulting in less thermal shock for the die casting mold due to the lower temperature difference between the melt and the die, which in turn increases service life. The service life of the filling chamber is also extended by reduced abrasive stress caused by the dampening effect of the solid particles, especially the chips, upon impact with the melt at the bottom of the filling chamber.

[0010] It has also been shown that the addition of solid particles improves the quality of the castings by reducing porosity and the number and size of cavities. Overall, this results in a sustainable process with increased quality, allowing the carbon footprint to be reduced.

[0011] Adding solid particles involves mixing molten metal and solid particles. It is therefore also possible to introduce the solid particles first, e.g., into a pressure channel or a transport device, and then add the molten metal. The only important thing is that they are combined.

[0012] According to a preferred embodiment, the molten metal is introduced into the die casting mold via a pressure generating device, wherein the solid particles are fed to the molten metal before or in the pressure generating device.

[0013] It has proven particularly advantageous if the solid particles are already added to the molten material before it is fed under pressure via the gating system of the die casting mold. Furthermore, the molten metal can be fed particularly easily at these points, e.g., into the flowing melt, i.e., into the flowing pouring stream, e.g., at the end of a feed chute.

[0014] The pressure under which the melt, here the molten metal containing solid particles, is introduced into the casting mold is preferably in a range of 150 to 1200 bar.

[0015] Advantageously, the addition of solid particles lowers the temperature of the molten metal. This means that the temperature of the mixture of molten metal and solid particles, for example, in the pressure channel of a pressure generating device, is lower than if no solid particles were added. Thus, when the melt is introduced into the die casting mold, it has a lower temperature than in the prior art, minimizing wear on the die casting mold. The metal temperature can thus drop below the technically feasible dosing temperature in the prior art, since thixostatic states of alloys cannot be dosed with conventional metal dosing methods in die casting. Until now, complete liquefaction of the dosing material was required.

[0016] According to a preferred embodiment, the temperature of the molten metal can be reduced by a temperature in the range of 40 to 90 °Kelvin by adding the solid particles. With an aluminum alloy such as EN AC-46000 / EN AC-AlSi9Cu3(Fe), the temperature of the molten metal can drop by 40°C to 60°C to a temperature of 590 to 610 °C in a pressure channel of the pressure generation device, depending on the amount of solid added. The lower temperatures have a positive effect on the die casting process. Consequently, the follow-up time can also be reduced. The follow-up time refers to the residence time of the liquid aluminum melt in the casting chamber. On the one hand, it is required to calm the metal after the dosing process. On the other hand, the melting temperature drops during this defined time.

[0017] The mass of added solid particles corresponds, for example, to 1 to 15%, particularly 2 to 10%, of the mass of the finished casting. With correspondingly high proportions, such as 10%, considerable savings in heating costs for melting the metal can be achieved, i.e., 10%. This is very advantageous from an ecological perspective.

[0018] Advantageously, the melting temperature of the solid particles is >= the temperature of the molten metal, so that the solid phase of the solid particles can be reliably maintained.

[0019] Advantageously, the melt, i.e. the metal containing the solid particles, has a semi-liquid state, with the liquid phase and solid phase existing side by side and with the added solid particles in particular not melting or at least not completely melting.

[0020] The solid particles are preferably designed to be free-flowing and can thus be easily introduced into the molten metal. They are preferably in the form of chips, particles, or granules. This means that the starting material is first crushed before being introduced into the molten metal.

[0021] According to a preferred embodiment, the added solid particles each have a mass of 0.001 g to 3 g, preferably 0.001 g to 2 g, in particular 0.001 g to 1 g. The solid particles can have the same mass or different masses. The above-mentioned mass range has proven particularly favorable, particularly with regard to handling and the material properties of the finished die-cast part. In this mass range, the solid particles can also be easily introduced into the mold cavity via the gating system. At masses above 3 g, flowability suffers.

[0022] The solid particles may be formed from at least one material from the following groups: metal, metal alloy, light metal, light metal alloy, aluminum, aluminum alloy, in particular

[0023] EN AC-46000 / EN AC-AlSi9Cu3(Fe) or also EN AC-46200 / EN AC-Al Si8Cu3, EN AC-46600 / EN AC-Al Si7Cu2, EN AC-47000 / EN AC-AlSi12(Cu), EN AC-47100 / EN AC-AlSi12Cu1(Fe), EN AC-42100 / EN AC-AlSi7Mg0.3, EN AC-42200 / EN AC-AlSi7Mg0.6, EN AC-43000 / EN AC-AlSi10Mg(a), EN AC-43200 / EN AC-Al Si10Mg(Cu), EN AC-43300 / EN AC-AlSi9Mg, EN AC-43400 / EN AC-AlSi10Mg(Fe), EN AC-43500 / EN AC-AlSi10MnMg, EN AC-44200 / EN AC-AlSi12(a), EN AC-44300 / EN AC-AlSi12(Fe)(a), EN AC-45000 / EN AC-AlSi6Cu4

[0024] The solid particles can all be made of the same material or of different materials. The solid particles can also be made of the same material as the molten metal or of a different material.

[0025] The metal that is melted is preferably formed from at least one material from the following group: EN AC-46000 / EN AC-AlSi9Cu3(Fe) or also EN AC-46200 / EN AC-Al Si8Cu3, EN AC-46600 / EN AC-Al Si7Cu2, EN AC-47000 / EN AC-AlSi12(Cu), EN AC-47100 / EN AC-AlSi12Cu1(Fe), EN AC-42100 / EN AC-AlSi7Mg0.3, EN AC-42200 / EN AC-AlSi7Mg0.6, EN AC-43000 / EN AC-AlSi10Mg(a), EN AC-43200 / EN AC-Al Si10Mg(Cu), EN AC-43300 / EN AC-AlSi9Mg, EN AC-43400 / EN AC-AlSi10Mg(Fe), EN AC-43500 / EN AC-AlSi10MnMg, EN AC-44200 / EN AC-AlSi12(a), EN AC-44300 / EN AC-AlSi12(Fe)(a), EN AC-45000 / EN AC-AlSi6Cu4.

[0026] Advantageously, the solid particles are added in a controlled quantity during each casting cycle via a feed device, particularly a screw conveyor. This allows a predetermined amount of solid particles to be added per casting at any time, ensuring consistent quality and an automated process.

[0027] It is particularly advantageous when metal scrap is crushed into solid particles and used as an additive to the molten metal. This can save not only energy costs but also material costs.

[0028] A device, in particular for carrying out the method according to at least one of claims 1 to 13, comprises a pressure-generating device and a die-casting mold, wherein the pressure-generating device can introduce molten metal under pressure into the die-casting mold. Advantageously, the device comprises a feed device via which solid particles can be fed to the molten metal.

[0029] The feeding device is advantageously arranged in such a way that the solid particles can be fed to the molten metal before or in the pressure generating device but after the device for melting the metal.

[0030] Advantageously, the feed device is a dosing device, in particular a screw conveyor, which is preferably controlled by a controller such that a specific amount of solid particles can be fed in per casting cycle. This allows a consistent process with consistent quality of the cast parts to be achieved, which further optimizes the process and the quality of the cast parts.

[0031] The solid particles preferably each have a volume in the range of 0.8 cubic millimeters to 15 cubic millimeters, preferably 1.2 cubic millimeters to 15 cubic millimeters, and even more preferably 1.2 cubic millimeters to 5 cubic millimeters. Such solid particles can be easily produced, especially during the comminution of scrap.

[0032] The present invention is explained in more detail below with reference to the following figures: Figure 1 shows a roughly schematic representation of an embodiment of a device for carrying out the die-casting process according to the invention with a filled pressure channel. Figure 2 shows a roughly schematic representation of the Fig. 1 shown device in which the mold cavity is filled. Figure 3 shows a rough schematic of the Fig. 1 The device shown in which the die-casting mold halves are open. Figure 4 shows a schematic flow diagram of a method according to the invention.

[0033] As from the Figure 1 As can be seen, the device 1 comprises a die casting mold 6 with the two mold halves 6a and 6b. The mold halves 6a and 6b are in Figure 1closed in a known manner. The die casting mold 6 has a mold cavity 9 into which melts, i.e. molten metal, can be introduced under pressure. For this purpose, the device 1 has a pressure generating device 3 with a piston 5 and a pressure channel 4. The pressure channel 4 here has an inlet 11 for the molten metal 2 at its upper end facing the piston 5. The molten metal 2 can, for example, be poured into the pressure channel 4 via the inlet 11. The metal 2 is previously melted in a device (not shown) and is brought to the inlet 11 via a transport device. The transport device can, for example, be an inclined pouring trough or a vacuum pipette.

[0034] In addition, the device 1 has a feed device 8, here, for example, a conveyor screw 8, which can be controlled by a controller (not shown) to feed metered amounts of solid particles 7 from a storage container (not shown) to the molten metal 2. Here, for example, the feed device 8 is also arranged in the region of the inlet 11 of the pressure generating device 3. Advantageously, the solid particles 7 are fed upstream of a gating system 10. In Figure 1 the pressure channel 4 is filled with molten metal in which solid particles 7 are located.

[0035] The piston 5 is, as indicated by the arrow P in Figure 1 shown, is movable in direction P and can, as can be seen Figure 2The molten metal together with the solid particles 7 is pushed under pressure into the mold cavity 9 of the die 6 via the gate system 10. The metal 2 can solidify together with the solid particles 7 and can then, as can be seen in particular from Figure 3 , by moving the die casting mold halves 6a, 6b apart via an ejection device 12, as shown by the arrow, whereupon the finished casting 20 can be removed. In this case, for example, half 6b moves to the right and half 6a remains stationary.

[0036] The device shown is only an example. In principle, any conventional die-casting equipment can be used, as long as it is possible to add solid particles to the already molten metal.

[0037] The method according to the invention is described below with reference to Figures 1 to 4 explained in more detail.

[0038] The process according to the invention is suitable for all conventional die-casting processes in which solid particles can be added accordingly and is explained in more detail here using the following exemplary embodiment.

[0039] As metal 2, a material from the following group is particularly suitable: metal, metal alloy, light metal alloy, in particular the previously mentioned die-cast alloys. In this embodiment, the metal is Step S1 e.g. Melted in a known manner at a temperature in the range of 650°C to 720°C. In this specific embodiment, the metal or material is EN AC-46000.

[0040] The molten metal 2 is Step S2 to the pressure generating device 3 and as shown in Figure 1 is filled into the pressure channel 4 via the inlet 11.

[0041] In a Step S3The solid particles 7 are added either before, during, or after the molten metal is poured into the pressure channel 4. The solid particles can be added, for example, on the transport path between the device for melting the metal (not shown) and the inlet 11, or in the region of the inlet, or via a separate inlet for solid particles in the pressure generating device (not shown).

[0042] The solid particles can be fed in via the conveyor screw 8. Even though feeding via a feeding device 8 is shown here, it is also possible in principle to manually feed a specific amount of solid particles 7. For this purpose, the feeding device, here, for example, the conveyor screw 8, can be controlled via a control device (not shown) to meter in a specific amount of solid particles per casting cycle.

[0043] The solid particles 7 are formed from at least one material from the following group: metal, metal alloy, light metal, light metal alloy, in particular the die-casting alloys mentioned above for the solid particles.

[0044] The solid particles 7 can be made of the same material as the metal 2 or of a different material. The solid particles 7 can all be made of the same material or different materials. In this specific embodiment, the material of the solid particles is, for example, EN AC-46000.

[0045] The individual added solid particles 7 each have, for example, a mass of 0.001 g to 3 g, in particular 0.001 g to 2 g, more preferably 0.001 g to 1 g, and are designed here such that they are free-flowing and can thus be easily transported by a dosing device, such as a conveyor screw 8. The solid particles can have the same or different masses. The solid particles 7 are in particular in the form of chips or particles or granules, etc. In this exemplary embodiment, the solid particles are formed, for example, from EN AC-46000 and have, for example, the following dimensions: 5 mm - 3 mm - 0.5 mm. The solid particles particularly preferably each have a volume in a range of 0.8 cubic millimeters - 15 cubic millimeters, preferably 1.2 cubic millimeters - 15 cubic millimeters and even more preferably 1.2 cubic millimeters - 5 cubic millimeters.Such solid particles can be easily produced, especially when crushing scrap.

[0046] In this case, the melting temperature of the solid particles 7 is preferably greater than or equal to the melting temperature of the metal, such that the solid particles 7 do not melt, or at least not completely, and are present in the melt, i.e., in the molten metal, in a solid phase, i.e., the metal containing the solid particles has a semi-liquid state, i.e., a semi-liquid quality in which the liquid phase and solid phase exist side by side. In such a semi-liquid state, the metal 2 can be introduced into the die 6 under pressure, e.g., between 150 bar and 1200 bar. Advantageously, the mass of the solid particles added in one pressure cycle comprises 1 to 15%, in particular 2 to 10% of the mass of the finished casting, in this specific embodiment, e.g., 10%. This means that in Step S1correspondingly less, here for example 10% less thermal energy is required, compared to conventional die casting processes.

[0047] Furthermore, it is possible for metal scrap to be crushed as solid particles 7 and used as an additive for the molten metal 2. This saves material costs and simultaneously disposes of scrap.

[0048] By adding the solid particles 7, the temperature of the molten metal 2 is reduced. The temperature of the molten metal 2 can be reduced, for example, by a temperature of 40 to 90° K, so that the temperature of the molten metal 2 containing the solid particles 7 in the pressure channel 4 preferably drops to a temperature of 560° C to 680° C, in particular to 590° C to 610° C.

[0049] As from Figure 4 is then shown in a Step S4The semi-liquid melt is introduced into the die-casting mold 6 under pressure, e.g., under a pressure of 150 to 1200 bar. Both the molten metal 2 and the solid particles 7 are pressed into the mold cavity 9 via the gating system 10. Solid particles also collect in the area of ​​the gating system 10, which can be recognized as solid particles when the mold halves are opened. The solid particles 7 are evenly distributed throughout the casting 20 to be produced.

[0050] In Step S5 the melt solidifies, ie the molten metal containing solid particles 2. As can be seen from Step S6 shows After solidification, the finished casting 20 is ejected.

[0051] According to the invention, a casting 20 with excellent material properties is produced with a shortened solidification time. In particular, the formation of pores and cavities is positively influenced. Furthermore, wear on the die casting mold is minimized and thermal shock is reduced due to the lower temperatures, which in turn increases the service life.

[0052] Overall, the die-casting process and device according to the invention are sustainable and enable a reduction in the CO2 footprint.

Claims

1. A die-casting process for a metal (2) in the form of aluminum or an aluminum alloy, comprising the following steps: - melting the metal (2) - introducing the metal (2) under pressure into a die-casting mold (6) - solidifying the metal (2) in the die-casting mold (6) characterized in that solid particles (7) are added to the molten metal.

2. Die-casting process according to claim 1, characterized in that the molten metal (2) is introduced into the die casting mold (6) via a pressure generating device (3) and the solid particles (7) are fed to the molten metal (2) before or in the pressure generating device (3).

3. Die-casting process according to claim 1 or 2, characterized in that the pressure under which the molten metal (2) containing the solid particles is introduced into the casting mould (6) is in a range of 150 to 1200 bar.

4. Die-casting process according to at least one of claims 1 to 3, characterized in thatthe temperature of the molten metal (2) is reduced by adding the solid particles (7).

5. Die-casting process according to at least one of claims 1 to 4, characterized in that the temperature of the molten metal (2) decreases by a temperature in a range of 40 to 90 °Kelvin by adding the solid particles (7), in particular in the case of an aluminum alloy, to a temperature of 590 °C to 610 °C in a pressure channel (4) of the pressure generating device (3).

6. Die-casting process according to at least one of claims 1 to 5, characterized in that the mass of the added solid particles (7) corresponds to 1 to 15%, in particular 2 to 10% of the mass of the finished casting (20).

7. Die-casting process according to at least one of claims 1 to 6, characterized in that the melting temperature of the solid particles (7) is greater than or equal to the melting temperature of the metal (2).

8. Die-casting process according to at least one of claims 1 to 7, characterized in that the molten metal containing the solid particles has a semi-liquid state, wherein the liquid phase and solid phase exist side by side and wherein in particular the added solid particles (7) do not melt or at least do not melt completely.

9. Die-casting process according to at least one of claims 1 to 8, characterized in that the added solid particles (7) are preferably free-flowing and are in particular manufactured in the form of chips or particles or granules and preferably each have a mass of 0.001g to 3g, preferably 0.001g to 2g, in particular 0.001g to 1g.

10. Die-casting process according to at least one of claims 1 to 19, characterized in thatthe solid particles formed from at least one of the following material groups: Metal, metal alloy, alloy, alloy, aluminum, aluminum alloy, in particular EN AC-46000 / EN AC-AlSi9Cu33(ACF / EN-2004), EN-2 AC-Al Si8Cu3, EN AC-46600 / EN AC-Al Si7Cu2, EN AC-47000 / EN AC-AlSi12(Cu), EN AC-47100 / EN AC-AlSi12Cu1(Fe), EN AC-42100 / EN-AlSi12Cu1(Fe), EN AC-42100 / EN-AlSi12, AC-42200 / EN AC-AlSi7Mg0.6, EN AC-43000 / EN AC-AlSi10Mg(a), EN AC-43200 / EN AC-Al Si10Mg(Cu), EN AC-43300 / EN AC-AlSi9Mg / EN-4340 AC-AlSi10Mg(Fe), EN AC-43500 / EN AC-AlSi10MnMg, EN AC-44200 / EN AC-AlSi12(a), EN AC-44300 / EN AC-AlSi12(Fe)(a), EN AC-400 / ENCu-AlSi / or the metal (2) in particular from a material of the following group is: EN AC-46000 / EN AC-AlSi9Cu3(Fe), EN AC-46200 / EN AC-Al Si8Cu3, EN AC-46600 / EN AC-Al, SiENCu2 AC-47000 / EN AC-AlSi12(Cu), EN AC-47100 / EN AC-AlSi12Cu1(Fe), EN AC-42100 / EN AC-AlSi7Mg0.3, EN AC-42200 / EN AC-AlSi7Mg0.6, ENEN AC-43000 / EN AC-AlSi10Mg(a), EN AC-43200 / EN AC-Al Si10Mg(Cu), EN AC-43300 / EN AC-AlSi9Mg, EN AC-43400 / EN AC-AlSi10Mg(Fe), EN AC-43500 / EN AC-AlSi10MnMg, EN AC-44200 / EN AC-AlSi12(a), EN AC-44300 / EN AC-AlSi12(Fe)(a), EN AC-45000 / EN AC-AlSi6Cu4., 11. Die-casting process according to at least one of claims 1 to 10, characterized in that the solid particles (7) are quantitatively dosed in each casting cycle via a feeding device (8), in particular a conveyor screw (8).

12. Die-casting process according to at least one of claims 1 to 11, characterized in that as solid particles (7) metal scrap is crushed and used as an additive for the molten metal (2) and / or the solid particles preferably each have a volume in a range of 0.8 cubic millimeters - 15 cubic millimeters, preferably of 1.2 cubic millimeters - 15 cubic millimeters and even more preferably of 1.2 cubic millimeters - 5 cubic millimeters.

13. Devices (1), in particular for carrying out the method according to at least one of claims 1 to 12, with a pressure generating device (3) and a die casting mold (6), wherein the pressure generating device (3) can introduce molten metal (2) under pressure into the die casting mold (6), characterized in that the device has a feeding device (8) via which solid particles (7) can be fed to the molten metal.

14. Device (1) according to claim 13, characterized in that the feeding device (8) is arranged such that the solid particles (7) can be fed to the molten metal (2) in front of or in the pressure generating device.

15. Device (1) according to claim 13 or 14, characterized in that the feeding device (8) is a dosing device, in particular a conveyor screw (8), which is preferably controlled by a controller such that a predetermined amount of solid particles (7) can be fed per casting cycle.

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