DE102019125680B4 - Process for manufacturing a component - Google Patents

Abstract

Method for producing a component (11), in which an aluminum-based alloy (20) is provided in the liquid state and the component (11) is produced therefrom by die-casting, characterized in that the alloy (20) contains less than 1.3% by weight -% iron, not more than 0.2% by weight silicon, 2.7 - 5.0% by weight magnesium, not more than 0.2% by weight copper and not more than 0.1% by weight manganese, the total weight percentage of any other elements other than aluminium, magnesium, iron, silicon, copper and manganese is below 0.05% by weight.

Description

The invention relates to a method for producing a component, having the features of the preamble of claim 1, and the use of an aluminum-based alloy to produce a component.

the DE 601 26 529 T2 discloses an aluminum-magnesium alloy die-cast product. In addition to aluminum, the alloy contains, among other things, 2.7-6.0% by weight of magnesium, a maximum of 1.0% by weight of iron and a maximum of 1.4% by weight of silicon. Manganese is envisaged as an essential additive element, with the understanding that manganese levels below 0.4 cannot provide sufficient strength and corrosion resistance for the alloy. Zinc is also envisaged as an essential alloying element, which should be present in a range from 0.1 to 0.9%.

the DE 10 2009 026 725 A1 discloses a cast aluminum alloy product. In addition to aluminum, the alloy contains, among other things, 2.8-5.3% by weight magnesium, less than 0.85% by weight iron, less than 1.2% by weight silicon, 0.5-2.0% by weight -% manganese and 0.2-0.9% by weight zinc. The cast aluminum alloy can also be used for die casting, among other things.

the DE 39 26 576 A1 discloses a steering wheel skeleton in which at least the steering wheel hub and steering wheel spokes are integrally die cast from aluminum alloy and the spokes are cast around the steering wheel rim. In addition to aluminum, the alloy contains 2.5-3.5% by weight magnesium, 0.40-0.60% by weight iron, 0.10-0.30% by weight silicon, 0.25-0. 45% by weight manganese, 0.015-0.05% by weight copper and 0.035-0.085% by weight zinc.

the DE 602 00 169 T2 discloses an aluminum alloy for high-pressure injection molding which, in addition to aluminum, contains 3.6-5.5% by weight magnesium, 0.6-1.2% by weight manganese and 0.2-0.5% by weight contains nickel. Exemplary embodiments show a silicon content of 0.1% by weight and an iron content of 0.2% by weight.

Components made of aluminum or aluminum alloys are used in different areas, especially in automobile construction. Compared to steel components, in addition to the higher corrosion resistance, the lower density is also an advantage. The latter enables weight to be minimized, even if greater material thicknesses are sometimes necessary in order to achieve the desired material properties. Various processes can be used to manufacture aluminum components (which in this context includes aluminum alloy components). In addition to primary forming, this includes both hot forming and cold forming. A common process for manufacturing aluminum components, e.g. body parts, is die casting. In this process, aluminum or the aluminum alloy in a liquid state is pressed under pressure into a mold cavity, where it solidifies.

A component manufactured in this way often has to be connected to another component. Depending on the composition of the other component, different joining methods can be used. A frequently occurring combination in automotive engineering involves the joining of an aluminum component with a steel component. In this case in particular, joining is often carried out by forming. A method used here is punch riveting, in which a specially designed rivet not only serves as a connecting element, but also as a cutting punch. In a variant of the method, two sheets of metal are connected to one another, with the rivet only punching through the upper sheet, while the lower sheet, like the rivet itself, is only formed. In order to achieve the latter goal in particular, sufficient ductility is necessary, since otherwise undesirable cracks or fractures can occur.

Not all aluminum alloys that are suitable for die casting can be used to produce components that are sufficiently suitable for joining processes such as punch riveting. This applies, for example, to aluminum alloys that have a significant proportion of silicon, for example between 5 and 10% by weight (the terms “% by weight” and “percent by mass” being used interchangeably here and below). Such alloys generally have a significantly reduced ductility. In addition, silicon-free alloys such as Castaduct®-42 (AIMg4Fe2) are also known in the prior art, which in comparison have improved ductility. Nevertheless, depending on the dimensions of the components to be connected and the composition of the other component, for example, cracks can occur in the material even when using these alloys, which can impair the mechanical stability of the connection and possibly the corrosion resistance.

the U.S. 9,920,401 B2 discloses a high thermal conductivity aluminum alloy intended for die casting. In addition to aluminum, the alloy contains 0.2-2.0% by weight magnesium, 0.1-0.3% by weight iron and 0.1-1.0% by weight cobalt. It is intended in particular for the production of LED components.

From the U.S. 9,715,971 B2 there is known an electrode for a secondary battery comprising aluminum alloy foil. The aluminum alloy contains 0.03 - 0.1% by weight iron, up to 0.1% by weight silicon, and optionally titanium and copper. The alloy is first cast by continuous or semi-continuous casting into an ingot, which is then thermally homogenized and then rolled to produce the foil. the US 2013/0269842 A1 relates to a similar electrode, the aluminum alloy in this case containing 0.03-0.1% by weight iron, 0.01-0.1% by weight silicon and small amounts of copper.

the U.S. 2018/0 274 073 A1 discloses a high-strength aluminum alloy which, in addition to aluminum, contains 0.3-1.0% by weight of iron, 1.2-2.6% by weight of magnesium and also zinc, nickel, copper, zirconium, titanium, scandium and chromium. It is envisaged that iron and nickel will produce aluminides of an Al9FeNi phase which accounts for at least 2 percent by volume. Components can be cast or forged from the aluminum alloy.

From the CN 108 165 842 A an aluminum alloy is known which is particularly suitable for semi-solid processes. In addition to aluminium, the alloy contains 6.6-7.4% by weight silicon, at most 0.15% by weight iron, 0.15-0.25% by weight magnesium, as well as titanium, chromium, ytterbium, tellurium, beryllium and possibly traces of other elements.

the U.S. 2003/0 178 106 A1 discloses an aluminum alloy containing 6.5-8.5% by weight silicon, 0.6-1.0% by weight iron, 0.35-0.65% by weight magnesium and manganese, zinc, titanium, copper and bis to 0.15% by weight of other elements. The alloy is intended in particular for semi-solid processes.

the U.S. 5,115,770 A relates to an aluminum alloy containing up to 0.8% by weight iron, up to 0.6% by weight silicon as well as copper, manganese, vanadium, zirconium and optionally small amounts of zinc, manganese and nickel. The alloy can be used to die-cast components that have a particular tensile strength, even if they are exposed to elevated temperatures over long periods of time, e.g. a piston for an internal combustion engine.

In view of the state of the art shown, the production of components with increased ductility from an aluminum alloy by die casting still offers room for improvement.

The object of the invention is to enable the production of components with increased ductility from an aluminum alloy by die casting.

According to the invention, the object is achieved by a method having the features of claim 1.

A method for producing a component is disclosed, an aluminum-based alloy being provided in the liquid state and the component being produced from this by die-casting. It is proposed that the alloy contains less than 1.3% by weight iron, not more than 0.2% by weight silicon, 2.7 - 5.0% by weight magnesium, not more than 0.2% by weight copper and contains at most 0.1% by weight of manganese, the total weight percentage of any other elements other than aluminium, magnesium, iron, silicon, copper and manganese being less than 0.05% by weight.

The dependent claims relate to advantageous developments of the invention. The object is also achieved by using the features of claim 7 .

It should be pointed out that the features and measures listed individually in the following description can be combined with one another in any technically meaningful way and show further refinements of the invention. The description additionally characterizes and specifies the invention, in particular in connection with the figures.

The invention provides a method for producing a component. In this context, the term "component" is to be interpreted broadly and, in addition to fully finished parts that do not require further processing, also refers to parts that may be reworked before use, e.g. by machining, surface treatment, surface coating or similar. In particular, the term also includes semi-finished products in this context.

In the process, an aluminum-based alloy is provided in a liquid state and the component is produced from this by die-casting. In this context, the aluminum-based alloy, one could also say aluminum alloy, preferably contains at least 70% by weight, more preferably at least 80% by weight, even more preferably at least 90% by weight aluminum. In addition to aluminum, it has other elements, which can be metals and possibly also at least one semimetal and/or nonmetal. The alloy is provided in the liquid state. The alloy is usually melted as a whole, but if necessary individual components of the alloy can also be melted and then mixed to form the alloy.

After the liquid alloy is provided, the component is die-cast from the alloy. The term "die casting" generally refers to a primary shaping process in which the alloy in a liquid state is pressed into a mold under pressure. The mold is usually preheated to prevent premature hardening of the alloy. Optionally, it can have means for heating and, if necessary, means for cooling. The alloy can be introduced into a predominantly closed mold cavity through at least one transfer opening. Pressure is still maintained as the alloy cools and eventually solidifies in the mold cavity. The mold cavity is a hollow space that is formed inside the mold. The mold can be formed by two mold halves, for example, which are joined together before the alloy is introduced in order to form the mold cavity. The latter is mostly closed, but has at least one transfer opening for introducing the alloy. The alloy can also be introduced into the mold cavity simultaneously or sequentially through a plurality of transfer openings. After the alloy has solidified within the mold, the mold can be opened, e.g. by separating the mold halves, and the workpiece can be removed.

As already mentioned above, the alloy contains less than 1.3% by weight iron, at most 0.2% by weight silicon and 2.7 - 5.0% by weight magnesium. The alloy can be processed without problems in die casting and the components manufactured according to the invention have a high ductility or high breaking point. In order to achieve a corresponding ductility, no heat treatment of the component is necessary, but it is given immediately after casting and cooling of the component. This has a positive effect, for example, when the component is subsequently connected to another component by punch riveting. The increased ductility reduces the risk of fractures or cracks in the component.

Without this having to be interpreted restrictively, it can be assumed that various factors have a positive influence on the ductility. First of all, this includes the small proportion of silicon, which within the scope of the invention can also be negligibly small, so that the alloy can also be regarded as (almost) silicon-free. It is believed that the formation of silicon mixed phases generally leads to a reduction in ductility. In addition, since the iron content is limited to less than 1.3% according to the invention, the formation of an Al13Fe4 phase during cooling and solidification is delayed and the proportion of this phase in the hardened alloy is reduced, which has an advantageous effect on the ductility or .affects the breaking point of the finished component. Finally, the alloy has a magnesium content that is significantly higher than, for example, alloys commonly used for die casting, such as AlSi9Cu3(Fe), AlSi12Cu1(Fe), AISi12(Fe) or AISi10Mg(Cu), which may have a positive effect on strength affects. The magnesium can also be contained in combination with iron, so that one can speak of an aluminium-magnesium-iron alloy. In the finished component, the magnesium can then be present within an Al3Mg2 phase.

The alloy preferably contains at most 0.1% by weight or at most 0.05% by weight silicon. The proportion of silicon can ideally be reduced even further, for example to at most 0.01% by weight or at most 0.001% by weight, so that the alloy can be regarded as essentially silicon-free. The proportion of silicon is advantageously reduced to unavoidable impurities.

According to one configuration, the proportion of iron can be reduced even further, so that the alloy contains at most 1.0% by weight of iron. Under certain circumstances, the iron content can also be at most 0.7% by weight or at most 0.5% by weight.

While reducing iron levels has the positive effects described above, reducing iron levels “to zero” is unnecessary. A certain non-negligible proportion of iron can be advantageous for setting certain alloy properties. Furthermore, it has been shown that with this the wear within the mold is lower than without iron content. From this point of view, it is preferable that the alloy contains at least 0.1% by weight of iron. It can also be advantageous for the alloy to contain at least 0.3% by weight of iron.

The alloy preferably contains 3.0-4.6% by weight of magnesium. More preferably, the lower limit for the magnesium content can be 3.2% by weight, 3.4% by weight or 3.6% by weight. The upper limit for the magnesium content can more preferably be 4.5% by weight or 4.4% by weight.

Typically, the alloy contains at most 1.0% by weight of other elements other than aluminum, magnesium, iron and silicon. More preferably, the proportion of these elements is less than 0.5% by weight. Such further elements that are optionally contained could be, for example, metals that can be selected in particular from copper, manganese, zinc, molybdenum, zirconium, beryllium and titanium. According to the invention, the other elements can be copper in a proportion by weight of at most 0.2% by weight and manganese in one 0.1% by weight at the most, with the total weight percentage of any other elements (other than Al, Mg, Fe, Si, Cu and Mn) being less than 0.05% by weight.

In particular, a component for a motor vehicle can be produced with the method according to the invention. The component can be provided for the chassis or the body. All components that can be produced by die-casting in terms of shaping and for which increased ductility is advantageous come into consideration here. This could be trim panels, support members, suspension components, engine components, or others. The method is also suitable for producing a component which is then to be joined to a second component by self-piercing riveting (SPR) to form a composite component. The second component can consist in particular of steel. The increased ductility achieved according to the invention is advantageous in this connection method. Other joining methods that take advantage of this ductility include flow-drilling bolting, high-speed bolting, friction welding, and weld riveting.

The invention also relates to the use of an aluminum-based alloy for the production of a component by pressure die casting, the alloy containing less than 1.3% by weight iron, at most 0.2% by weight silicon, 2.7-5.0 Contains by weight magnesium, not more than 0.2% by weight copper and not more than 0.1% by weight manganese, the total weight fraction of any other elements other than aluminum, magnesium, iron, silicon, copper and manganese , is below 0.05% by weight. The terms mentioned have already been explained with reference to the method according to the invention and are therefore not explained again. Advantageous configurations of the use according to the invention correspond to those of the method according to the invention.

• 1 eine schematische Darstellung einer ersten Stufe eines erfindungsgemäßen Verfahrens;
• 2 eine schematische Darstellung einer zweiten Stufe des erfindungsgemäßen Verfahrens; sowie
• 3A-3E verschiedene Stufen eines Fügeverfahrens unter Verwendung eines erfindungsgemäß hergestellten Bauteils.

Further advantageous details and effects of the invention are explained in more detail below with reference to different exemplary embodiments illustrated in the figures. It shows

• 1 a schematic representation of a first stage of a method according to the invention;
• 2 a schematic representation of a second stage of the method according to the invention; such as
• 3A-3E different stages of a joining process using a component produced according to the invention.

In the different figures, the same parts are always provided with the same reference numbers, which is why they are usually only described once.

1 FIG. 1 shows a highly schematized device 1 that can optionally be used to carry out a method according to the invention. In this case, a component is to be produced by die-casting from an aluminum-based alloy 20 . A mold 2 with a first mold half 2.1 and a second mold half 2.2 can be seen, which, when joined together, define a mold cavity 3 between them. On one side the mold cavity 3 is connected to a transfer opening 4 which in turn is connected to a container 5 . The container 5 has a filling opening 6 through which the alloy 20 can be filled in liquid form. Inside the container 5, the alloy 20 is kept in the liquid state, with the required temperature being set by a tempering device 10, which can have means for cooling as well as means for heating. Furthermore, a mixing device 9 is arranged adjacent to the container 5, which can be designed, for example, to generate electromagnetic fields. These act on the alloy 20 and bring about improved mixing of the individual components. Both the temperature control device 10 and the mixing device 9 are purely optional components. Inside the container 5 there is arranged on the one hand a movable piston 7 and on the other hand a transfer hatch 8. The alloy 20 is initially enclosed between the piston 7 and the transfer hatch 8 (see 1 ).

For the actual forming process, the transfer hatch 8 is opened (see 2 ) while moving the piston 7 towards the mold 2. This moves the alloy 20 through the container 5 and further into the mold cavity 3 via the transfer port 4 while in the liquid state.

As pressure continues to be applied via the piston 7, the alloy 20 hardens in the mold cavity 3 and forms the desired component. In order to prevent premature curing, mold 2 is usually preheated. Optionally, the mold 2 could be provided with its own temperature control device, which has means for heating and, if necessary, means for cooling in order to set the temperature of the mold 2 . Even without subsequent heat treatment, the finished component has high ductility or a high breaking point.

Alloy 20 used in this example has the following components: Magnesium: 4.3% by weight Iron: 1.0% by weight Silicon: 0.1% by weight Copper: 0.1% by weight Manganese: 0.075% by weight Aluminum: rest

In the alloy according to the invention used here, the silicon content is 0.1% by weight. This proportion can be further reduced without impairing the advantageous properties described above, for example to 0.05% by weight, 0.01% by weight or 0.001% by weight.

In particular, the manufactured component could be a body component that is later connected to another component made of steel by self-piercing riveting (SPR). In this method, the increased ductility that occurs according to the invention is advantageous.

3A-3E FIG. 1 shows various phases of a method in which a component produced according to the invention, hereinafter referred to as aluminum part 11, is connected to a steel part 12 by punch riveting. Both parts 11, 12 are shown here as flat sheets, which is not to be understood as limiting. The aluminum part 11 is placed on a die 13, with the steel part 12 resting on the component 11. A semi-tubular rivet 14 is accommodated in a setting unit 15 (see 3A ). The setting unit 15 is placed on the steel part 12, whereby the intended joint is fixed. At the same time, the semi-tubular rivet 14 is advanced and placed ( 3B ). Further feed initially causes plastic deformation of the steel part 12 and the aluminum part 11 into the die 13, while the semi-tubular rivet 14 still retains its original shape ( 3C ). Furthermore, the semi-tubular rivet 14 only punches through the steel part 12 located at the top and plastically reshapes the aluminum part 11 located at the bottom to form a closing head 11.1 ( 3D and 3E ). At the same time, the shank of the semi-tubular rivet 14 is expanded, as a result of which the form-fitting connection is completed. It goes without saying that a high degree of deformation takes place in the area of the closing head 11.1, with a particularly high level of ductility being necessary in order to avoid cracks or fractures. It has been shown that components which have been produced according to the invention show a particularly low tendency to form cracks with this method.

Apart from the punch riveting shown here as an example, the aluminum part 11 can also be used advantageously in other connection methods, including in particular flow-drilling screwing, high-speed bolt setting, friction welding and weld riveting.

reference list

1

contraption

2

shape

2.1, 2.2

mold half

3

mold cavity

4

transfer port

5

container

6

filling hole

7

Pistons

8th

transfer hatch

9

mixing device

10

temperature control device

11

component

11.1

locking head

12

steel part

13

die

14

semi-tubular rivet

15

setting unit

20

alloy

Claims (7)

Method for producing a component (11), in which an aluminum-based alloy (20) is provided in the liquid state and the component (11) is produced therefrom by die-casting, characterized in that the alloy (20) contains less than 1.3 wt. -% iron, not more than 0.2% by weight silicon, 2.7 - 5.0% by weight magnesium, not more than 0.2% by weight copper and not more than 0.1% by weight manganese, the total weight percentage of any other elements other than aluminium, magnesium, iron, silicon, copper and manganese is below 0.05% by weight. procedure after claim 1 , characterized in that the alloy (20) contains at most 0.1% by weight of silicon. Method according to one of the preceding claims, characterized in that the alloy (20) contains at most 1.0% by weight of iron. Method according to one of the preceding claims, characterized in that the alloy (20) contains at least 0.1% by weight of iron. Method according to one of the preceding claims, characterized in that the alloy (20) contains 3.0 - 4.6% by weight of magnesium. Method according to one of the preceding claims, characterized in that a component (11) for a motor vehicle is produced. Use of an aluminum-based alloy (20) for producing a component (11) by die casting, the alloy (20) containing less than 1.3% by weight iron, at most 0.2% by weight silicon, 2.7 - 5.0% by weight of magnesium, not more than 0.2% by weight of copper and not more than 0.1% by weight of manganese, the total weight fraction of any other elements being different from aluminium, magnesium, iron, silicon, copper and manganese differ, is below 0.05% by weight.

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