EP2861364A2

EP2861364A2 - Metal cast component and method for producing a metal cast component

Info

Publication number: EP2861364A2
Application number: EP13726758.9A
Authority: EP
Inventors: Rüdiger BÄHR; Ingolf Behm; Stefan Scharf; Sven RÖPKE; Joachim SCHNEIBEL; Manja Krüger
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2012-06-16
Filing date: 2013-05-29
Publication date: 2015-04-22
Also published as: WO2013186055A3; KR20150004385A; DE102012011992A1; CN104379278A; WO2013186055A2

Abstract

The invention relates to a metal cast component (1), which is intended in particular for parts of internal combustion engines or piston compressors, such as pistons, gearboxes, crankcases and other housings and/or cylinder heads, wherein the cast component (1) consists at least in certain portions of an iron aluminide and/or is a composite cast component comprising at least two portions (2, 3), which consist of a cast iron and/or an iron aluminide and/or a light metal. The invention also relates to a method for producing a metal cast component (1), in particular for parts of internal combustion engines or piston compressors, such as pistons, gearboxes, crankcases and other housings and/or cylinder heads, which consists of one or more cast materials such as cast iron and/or iron aluminide and/or light metal, in which method a first portion (2) of the cast component (1) is produced in a first casting operation and a further portion (3) of the cast component (1) is produced in a further casting operation and a coating, in particular of iron aluminide and/or a nickel alloy, is applied as a coupling agent layer to the first portion (2) before the further casting operation.

Description

description

Metallic cast component and method of making a metallic cast component

The invention relates to a metallic cast component, in particular for parts of a

Internal combustion engine or a reciprocating compressor such as a piston, a cylinder head, a transmission housing, a crankcase and / or another housing is provided.

Furthermore, the invention relates to a method for producing a metallic cast component, in particular for parts of an internal combustion engine or a reciprocating compressor such as a piston, a cylinder head, a gear housing, a crankcase and / or another housing, which consists of a cast material or more cast materials, such as cast iron and or ferrous aluminide and / or light metal, in which a first portion of the cast component is produced in a first casting operation and a second portion of the cast component is produced in a second casting operation.

A method of the type mentioned is known from DE 10 2005 015 186 A1. Of the

described manufacturing process of Verbundgussbauteils comprises an at least two-stage casting process in a casting, wherein in a first process step, a casting of a first material in the casting device is produced by casting and then in a second process step, the composite casting is finished by replacing one or more cores the first step during the

Cooling of the first material cores are changed geometry used in the pouring device before the casting process is completed in the second process step by pouring the second material.

In order to improve the cohesive connection of two casting sections in a composite cast component, DE 100 02 440 A1 discloses a primer layer of a nickel-aluminum alloy and a nickel-titanium alloy to be applied to a cast part first, the cast part. A cylinder head with support structures for stabilizing a jacket made of light metal shows the document EP 2 024 1 16 B1. The loads of cast components for internal combustion engines increased by

Combustion pressure as well as increased combustion and exhaust gas temperatures are increasing especially with increasing downsizing measures. At the same time there is the

Requirement to keep the weight of the cast components as low as possible.

Against this background, the invention has the object, a cast component and a method for producing a cast component of the type mentioned in such a way that the cast component meets the increased requirements.

This object is achieved with a cast component according to the features of patent claim 1. The subclaims relate to particularly expedient developments of the invention.

According to the invention, two embodiments of a cast component are provided. The first embodiment relates to a cast component which exclusively comprises an iron aluminide. The second embodiment relates to a cast component which comprises one of at least two

Sections existing composite casting is, each of the sections has a different density with respect to the casting material. It turned out that too

Cast component, which is made entirely of ferric aluminide, which meets the increased requirements. Iron aluminide has characteristics similar to those of cast iron, particularly in terms of temperature resistance and strength, but the density of iron aluminide is similar to that of a light metal such as aluminum. Thus, according to the invention, a lightweight and at the same time durable cast component was created.

The cast component may also be a composite cast component, which consists of at least two sections, also called casting sections. These sections are created one after the other. Preferably, one of the sections is made of a more durable, denser material, such as a cast iron and / or an iron aluminide and / or a

Light metal. The other section is ideally made of a lighter material, such as ferric aluminide and / or a light metal. By using ferric aluminide or a combination of a durable material with a lightweight material, it is possible to produce a cast component that meets the increased requirements.

Particularly favorable combinations of cast iron cast iron with aluminide, aluminide with aluminum and aluminum with magnesium have proven. This is mainly due to the fact that these materials have similar thermal expansion coefficients, which reduces the formation of gaps and residual stresses. In another, preferred combination The casting materials cast iron and aluminum may indeed form a gap between the components cooled to room temperature, but this is not a problem since the material with the lower density heats up when the cast component is heated

Thermal expansion, causing this on the section with the lower

Thermal expansion shrinks and so closes the gap. Other material combinations are cast iron with magnesium or iron aluminide with aluminum or iron aluminide with magnesium. The materials mentioned relate both to the pure material and to alloys on which the corresponding material is based.

The sections may also be referred to as casting areas, with a section made earlier in terms of time also being called a cast part. A Eingussteil, which is provided in an at least partially solidified state for placement in another casting tool is also referred to as a depositor. In a cast component of two sections, the first section, the cast part or the insert can be produced from both the resistant material and from the light material. It has proven to be particularly practical in production that the first section produced is made of the durable material. In particular, in an intermediate storage or the introduction into another casting tool this is easier to handle, because it is less sensitive. When using iron aluminide, the use of Fe _x Al, in particular of Fe ₃ AI has proven to be particularly favorable.

In one embodiment of the invention, it is provided that between two adjacent sections a coating of an iron-aluminide and / or a nickel alloy is applied as a primer layer. This makes it possible, a considerable

Savings potential in the production costs to create. By using an iron aluminide, in particular as a primer layer, simple casting plants and simple casting techniques can be used, as a targeted adjustment of certain microstructures, especially in the light metals such as aluminum, is not necessary. In addition, it is also possible to use secondary raw materials such as recycled aluminum. Also, a casting subsequent process of heat treatment can be omitted. The coating is at most 20 millimeters thick, but preferably thinner than 2 millimeters, and thus substantially thinner than the section of a section. Iron aluminides are characterized by extremely high strengths, even at high temperatures. Compared with classic steels, they have a significantly reduced density and, at the same time, very good corrosion resistance

different media. As a bonding agent layer between the materials iron and Aluminum is the material iron-aluminide especially due to its chemical composition.

A further embodiment of the invention relates to a cast component, in which one of the sections of a combustion chamber and / or a gas line of an internal combustion engine

or a piston compressor is associated and / or limited. The first section is for example a boundary wall of a combustion chamber and comprises at least one outlet opening of the combustion chamber for exhaust gas. Preferably, the first produced section is an insert, which is at least partially surrounded by at least one second section. Since the portion defining the combustion chamber or an exhaust pipe of an internal combustion engine is subjected to higher stress than other portions of the cast component by temperature and / or pressure, this first portion is preferably made of a steel, cast iron, iron aluminide or high-strength light metal alloy. The insert enclosing portion is also called shell casing. The jacket housing is preferably made of an iron-aluminide or light metal.

An embodiment of the invention also relates to a cast component, in which the first section with respect to geometry, pressure and temperature resistance as a support member of

Cast components is executed. Such a support structure in the interior and / or on the

Exterior surfaces of the casting provide additional stability, fatigue strength and rigidity to another section made from a lightweight, lower density material. Even by such a local reinforcement by partial use of high-strength materials, the specific power of an internal combustion engine can be increased. For example, a cast component for a cylinder head, a separation of the different media-carrying channels by the combination of the light metals aluminum and magnesium take place. At the same time, this cast component can have individual cast iron surfaces for shielding from the hot gases of the combustion chamber and a cast iron or iron-aluminide support structure for increasing the rigidity or for reducing stress peaks.

An embodiment of the invention is that the first section is designed as a heat protection element or cooling element. A heat protection element reflects the heat radiation so that it can not penetrate into the depth of the cast component. At the same time a

Heat protection element also realize the function of a cooling element and dissipate heat targeted. As a cooling element, heat exchangers with a large surface area are also referred to. It is also an embodiment of the invention that a section which is a boundary wall of at least one combustion chamber comprising at least one outlet opening of the combustion chamber for exhaust gas comprises an exhaust manifold. By integrating the exhaust manifold into, for example, a so-called combustion chamber plate of a cylinder head housing, the cylinder head housing and the exhaust manifold become a one-piece cast component. This saves on the one hand manufacturing steps and on the other hand eliminates the costly connection of the exhaust manifold to the cylinder head housing, which must be resistant to high temperatures and high pressure. The cast together with one of the sections

Exhaust manifold according to the invention consists for example of a cast iron and / or an iron aluminide.

The invention also makes it possible to combine areas of the internal combustion engine that fulfill different functions in a cast component. Exemplary is an embodiment in which the cast component is a cylinder head or a cylinder housing, of which a portion is integrally formed with at least a part of a housing of a turbocharger. This makes it possible to reduce the number of parts and the assembly cost.

Furthermore, it has proven to be advantageous that in each section an independent water jacket is provided, in each of which a cooling fluid circulates. By independent casting process steps, in particular by the use of a section as a depositor, a separation of the media-leading areas in a simple manner possible. The separation of the media leading areas prevents corrosion as the cooling fluids in contact with different metals are separated. The vibration resistance in the region of a water jacket or a gas exchange channel can by the formation of a

Support structure can be achieved. The support structure is preferably made of an iron aluminide and is at least partially surrounded by an aluminum material.

For example, in trucks, cylinder heads made of cast iron are used.

Cylinder heads made of cast iron have the advantage that in the combustion chamber and the

Gas exchange channels high pressures can be achieved. Cylinder heads from one

Light metal such as aluminum are often used in passenger cars. These have the advantage of being light in weight. At higher temperatures, the strength of light metal decreases. In a hybrid cylinder head according to the invention of two sections, one section consists of a pressure-resistant material such as cast iron and the other section of a lightweight material, such as aluminum. The elements of the cast component of a Cylinder heads, which consist of pressure- or temperature-resistant materials, are for example the inlet and outlet channels. Other elements, for example conduits for cooling media or lubricants, are made of a light metal.

A mixture of iron and aluminum, iron aluminide, has proven to be particularly favorable to meet the higher requirements. According to the invention, the cast body of the cylinder head consists partly or completely of this material. In a cast body made of several materials, iron aluminide is combined according to the invention with cast iron and / or a light metal.

In a cast component, which consists of a combination of the materials cast iron and

Alloy exists, may form due to the different thermal expansion of the materials in the transition region columns. The use according to the invention of iron aluminide as adhesion promoter layer between two sections makes it possible to improve the material bond in the transition region between different light metal alloys or between light metal and cast iron and thus reduce the tendency to fission, in particular during cooling after casting. This is achieved above all by applying the iron aluminide as a coating to an existing section before producing a further section.

The object is further achieved by a method according to the features of

Claim 7. The dependent claims relate to particularly expedient developments of the invention.

According to the invention, therefore, a method is provided in which prior to a second casting operation on the first section a coating, in particular of iron aluminide as

Adhesive layer is applied. By using a primer layer of iron aluminide, it is possible to reduce the manufacturing costs compared to the prior art and to produce an improved cohesive connection between two sections in the casting. It is possible to use simple casting machines and casting techniques, since it is not necessary to deliberately adjust certain microstructures, in particular in light metals such as aluminum. In addition, it will be possible, even secondary raw materials, like again

to use recycled aluminum. It has been shown that especially ferric aluminide is characterized by extremely high strength values at relatively low density. Its thermal expansion behavior corresponds approximately to that of aluminum-silicon alloys, so that no increased residual stresses due to a material combination of For example, cast iron with aluminum can be expected. The production of a cast component from at least two different materials is also called hybrid casting.

The sections can be produced in a common casting tool. However, it has proved favorable that the sections are produced in separate casting tools, wherein the first section is arranged in the casting tool intended for the second or further casting operation before a second or further casting operation. In any case, the first cast and already partially or fully solidified section is surrounded by the second section. In this case, the sections connect materially.

An embodiment of the invention is when the method for producing a

Cast component is provided according to one of claims 1 to 6.

It is also favorable that the coating is applied by means of casting, dipping, spraying and / or thermal spraying. The coating forming a primer layer is ideally applied completely between the sections. The coating is a liquid or solid material. For a solid material, the use of powder or flakes is practical. A development of the method according to the invention is that the coating and the section on which the coating is applied are charged statically in opposite directions for application. The improved by the coating

Bonding between the sections reduces the gap formation during the cooling of the cast component after the casting process.

The iron aluminide for the primer layer is provided as a coating, preferably in a solid phase, for example as a powder. The application of the coating success preferably by means of thermal spraying, such as flame spraying, arc spraying or

High Speed Splash. In a development of the invention, the first section, in particular a first section provided as a depositor of the cast component, is subjected to sandblasting prior to coating.

It is advantageous that a first casting material is used in the first casting process and a second casting material is used in the second casting process. This is the first one

Cast material a different from the second casting material metallic

Alloy. When casting over a coated first section and / or first

Casting material with another section and / or other casting material, the coating is a material connection with both the first and with the another section and thus forms the adhesion promoter layer. This cohesive connection formed between the sections by means of a bonding agent layer has in particular during

Cooling of the cast component over the prior art, a lower tendency to form a gap.

The invention allows numerous embodiments. To further clarify its basic principle, three of them are shown in the drawing and will become hereafter

described. The drawing shows in

Fig. 1 is a schematic representation of a first embodiment of a portion of a cast component;

FIG. 2 shows a schematic representation of the section shown in FIG. 1 with the casting cores of a casting tool before the casting of a further section of the cast component; FIG.

3 shows a schematic exploded view of the section shown in FIG. 1 and of the further section of the cast component formed during casting;

FIG. 4 shows a schematic representation of the cast component shown in FIG

cohesively connected sections;

5 shows a schematic representation of a cast component with two sections and a coating provided therebetween;

6 shows a schematic representation of a flow chart of the method for producing a cast component;

Fig. 7 is a schematic representation of a combustion chamber of a

Internal combustion engine side facing away from the portion of a cast component shown in Figure 1;

Fig. 8 is a schematic representation of a combustion chamber of a

Internal combustion engine facing side of the portion of a cast component shown in Figure 1; 9 shows a schematic illustration of a second embodiment of a section of a cast component with a support structure;

10 shows a schematic representation of a third embodiment of a section of a cast component with an exhaust manifold.

FIGS. 1 to 6 show a method for producing a metallic cast component 1. The cast component 1 shown by way of example here is a cylinder head of one not further

shown internal combustion engine. The cast component 1 is a hybrid cylinder head consisting of two different cast materials. A first section 2 of the cast component 1 consists of cast iron or iron aluminide, while a second section 3 of the cast component 1 consists of iron aluminide or a light metal. In a first casting operation 4, the first section 2 of the cast component 1 is produced in a first casting tool. The first section 2 taken from the first casting tool (not shown) is shown inter alia in FIG. After solidification, the first section 2 is inserted into a second casting tool 5. From the second casting tool in Figure 2, only one oil core 6 for generating a cavity, which later serves to receive a lubricant, and a water core 7 shown. The water core 7 generates in the second section 3 a cavity, also called water jacket 10, which can serve to receive a cooling medium or cooling fluid. A water jacket 1 1 arranged in the first section 2 is independent of the water jacket 10 of the second section 3. This serves to reduce corrosion in the cylinder head. In a subsequent second casting operation 9, the second section 3 of the cast component 1 is produced. In FIGS. 3 and 4, the complete cast component 1 with the first section 2 and the second section 3 can be seen. Before the second casting process 9, a coating 12 is applied to the first section 2

Adhesive layer between the first section 2 and the second section 3

The coating 12 is made of an iron aluminide and is preferably applied by thermal spraying. 8. The application of an iron-aluminide coating is dispensed with if the first section 2 and the second section 3 consist of an iron aluminide.

FIGS. 7 and 8 show the first section 2 in a first embodiment as a combustion chamber plate of a cylinder head. The combustion chamber plate comprises two gas outlet channels 13, two gas inlet channels 14 and also a part of the already described water jacket 1 1. In Figure 8, the combustion chamber facing side is shown. This side is also called cylinder head surface 15 and has outlet openings 16 of the gas outlet channels 13 and inlet openings 17 of the gas inlet channels 14. FIG. 9 shows a second embodiment of the cast component 1, in particular its first section 2. This first section 2 comprises a support element 18

Support structure. The second section 3 encloses the first section 2 and forms the

Shell casing a cylinder head, while the first portion 2 is designed as a combustion chamber plate with the cylinder head surface 15.

FIG. 10 shows a third embodiment of the cast component 1, in particular its first section 2. This first section 2 comprises an exhaust manifold 19. A housing of a turbocharger 20 is arranged on the exhaust manifold 19 by means of a screw connection.

LIST OF REFERENCE NUMBERS

cast component

first section

second / further section

first casting process

Insert oil core

water nuclear

Instruct

second casting process

Water jacket water jacket

coating

gas outlet

Gas inlet channel

Cylinder head surface outlet openings

inlets

support element

exhaust manifold

turbocharger

Claims

claims

1. Metallic cast component (1), in particular as a part of a

Internal combustion engine such as a piston, a cylinder head, a cylinder housing and / or a crankcase is provided, characterized in that the

Cast component (1) exclusively comprises an iron-aluminide or is, consisting of at least two sections (2, 3) composite casting member, wherein each of the sections (2, 3) has a different casting material with respect to the density.

2. cast component (1) according to claim 1, characterized in that at adjacent

Sections (2, 3) having one of the sections (2, 3) a cast iron alloy or an iron aluminide or an aluminum alloy and the other of the sections (2, 3) comprises an iron aluminide or an aluminum alloy or a magnesium alloy.

3. cast component (1) according to at least one of claims 1 or 2, characterized in that between two adjacent sections (2, 3) a coating (12) made of an iron-aluminide is applied as a primer layer.

4. cast component (1) according to at least one of claims 1 or 2, characterized in that one of the sections (2, 3), which has a denser cast material, a combustion chamber and / or a gas line of an internal combustion engine is assigned and / or limited ,

5. casting component (1) according to at least one of the preceding claims, characterized

characterized in that one of the sections (2, 3), which has a denser cast material, in terms of geometry, stress distribution, pressure and / or

Temperature resistance is designed as a support element (18) of the cast component (1).

6. cast component (1) according to claim 6, characterized in that one of the sections (2, 3), which has a denser cast material, an exhaust manifold (19) and / or parts of a housing of a turbocharger (20).

7. A method for producing a metallic cast component (1), in particular for parts of internal combustion engines such as pistons, cylinders, cylinder head housing and / or

Crankcase comprising one or more casting materials, such as cast iron and / or ferric aluminide and / or light metal, in which a first section (2) of the cast component (1) is produced in a first casting process (4) and in a further casting process (9 ), a further portion (3) of the cast component (1) is produced, wherein before the further casting process (9) on the first portion (2) a coating (12), in particular of iron aluminide, applied as a primer layer (8).

8. The method according to at least one of the preceding claims, characterized

in that in the first casting process (4) a first casting material and in the further casting process (9) a further casting material, in particular metallurgically different from the first casting material, is arranged in a casting tool.

9. The method according to at least one of the preceding claims, characterized

in that the two sections (2, 3) are produced in separate casting tools, and the first section (2) is arranged in the further casting tool provided for the further casting process (9) before a further casting operation (9),

in particular in the other casting tool inserted (5).

10. The method according to at least one of the preceding claims, characterized

in that the coating (12) is applied (8) to at least one of the sections (2, 3) by means of casting, dipping, spraying and / or thermal spraying.