DE102009034566A1 - Use of generative manufacturing method for layered structure of a component of a tank shell of a tank for liquids and/or gases, preferably fuel tank of e.g. satellite, where the component consists of titanium or an alloy of titanium - Google Patents

Abstract

Use of generative manufacturing method for layered structure of at least one component (1) of a tank shell of a tank for liquids and/or gases, where the component consists of titanium or an alloy of titanium, is claimed. An independent claim is also included for manufacturing a fuel tank, comprising: constructing at least one component of a tank shell of the tank layerwise with a generative manufacturing method, where the component consists of titanium or an alloy of titanium and exhibits a hollow shape, which is defined by a wall with a wall thickness, and further processing the component after the layerwise construction of the component, to produce the final dimension of the component.

Description

The The invention relates to a method for producing a tank for Fuel.

tanks for fuels, in particular fuel tanks for Satellites and aircraft are said to be made of a material that is light and at the same time has a high mechanical strength. Titanium and titanium alloys are in principle suitable materials for these fuel tanks as they want those Have properties.

titanium and titanium alloys, however, have the disadvantage of being difficult to edit. When cold forming thin titanium sheets the degree of springback is difficult to determine in advance, so that the contour of the deformed sheet is not determined reproducibly can be.

Further Problems with the deformation of titanium and titanium alloys are the risk of cracking, tool wear and tear embrittlement of the material, in particular during thermoforming, as well as a tendency to unevenness due to the anisotropy of thin sheets.

The DE 10 2007 014 948 A1 discloses a method for forming a titanium sheet, in which the titanium sheet is inserted in a sealed closed mold and is pressed there against a tool contour with a combination of a heated pressure medium on one side of the titanium sheet and a negative pressure on the other side of the titanium sheet and thereby deformed.

This Process has the disadvantage that the types of contours that produced can be limited. In particular, deeply deformed Making contours difficult with this method.

consequently It is an object of the present invention to provide a manufacturing method to provide a wider choice of shapes of titanium and titanium alloys can be produced, which is suitable for the production of a tank, in particular a fuel tank are suitable.

Solved this task is accomplished by the subject matter of the independent Claims. Advantageous developments are the subject the respective dependent claims.

According to the invention a generative manufacturing process for layered construction at least a component of a tank shell of a tank for liquids and / or gases used. This ingredient is made of titanium or from a titanium alloy.

With A generative manufacturing process is a part of a Base material built up in layers. Under generative manufacturing processes are to be understood as processes in which components directly and with the desired final contour can be produced. These parts are so strong that they the mechanical-technological functions "normal" produced Can take over components.

Generative manufacturing processes are also called rapid prototyping. These direct component production manufacturing methods are known in the art under a variety of names or designations such as "direct metal sintering"("DMS"),"powder metal sintering", "laser assisted metal sintering", "fusing" or "near net shaping". "Solid free form fabrication (SF ³ )", "additive layer manufacturing" (ALM), etc. The term "rapid manufacturing" is often used in the production of higher quantities recently. In the following, however, only the term "generative manufacturing process" is to be used, but this is not meant to be limiting, for example, only to a small number.

The The aforementioned generative manufacturing process is common to that the source material through one, usually from a CNC program controlled heat source (eg a laser or an electron beam) is melted locally and solidifies immediately afterwards. So is incrementally, following the CNC program, the 3-dimensional Component geometry more or less point by point or Layer by layer or layer by layer. Due to the melting and solidification, the component has a cast structure, which, however, by the high local cooling rate is much finer-grained than conventional cast structures.

These generative manufacturing processes allow the direct Manufacture of titanium and titanium alloy components have a thin wall structure. The problems of springback and cracking, which in the chipless deformation of sheets Titanium and titanium alloys, can occur be avoided. Furthermore, titanium components or a titanium alloy having an anisotropic shape with a generative one Manufacturing process made easier and more reliable than with a chipless deformation of a sheet of titanium or a titanium alloy.

A fuel tank shell has a thin wall that forms a tank with a nearly closed hollow shape. The advantages of using a generative process for making thin walled titanium and titanium alloy parts are used in the invention to produce a fuel tank. The tank may be a fuel tank of a satellite, aircraft, or vehicle or space shuttle, since the material properties of titanium and titanium alloys, particularly low weight, high strength, are particularly desirable in these applications.

The Invention also provides a method of manufacturing a fuel tank, in particular a fuel tank for a satellite. At least one component of a tank shell of the tank is provided with a generative manufacturing process built up in layers. This Part consists of titanium or a titanium alloy and has a hollow shape that passes through a wall with a wall thickness is defined. After building up the ingredient becomes this ingredient processed to produce the final dimensions of the component.

The Advantages of a generative manufacturing process are thus for producing constituents of titanium and titanium alloys used to make an intermediate. This intermediate can be further processed after its manufacture, to the material properties as well to further optimize the dimensions of the component.

In An embodiment is the layered structure of the component an energy beam onto a surface to be built up directed. On this surface, a starting material is made Titanium or a titanium alloy provided. From the starting material is with an energy beam on the surface to be built a molten area is generated and the energy beam is over the to be built up surface defined to be a Make layer of the ingredient.

Under The term "defined" is to be understood that the energy beam corresponding to a predetermined course, for example is determined with the help of a CAD program. The guiding of the energy beam is typically done with a controlled computer.

The Wall thickness of the layered constituent can between 2 mm and 10 mm, preferably between 3 mm and 5 mm. After further processing of the component, the wall thickness reduced to 1 mm to 3 mm to the weight of the component to reduce and refine the contour.

In Further embodiments, the energy beam is so defined that the component in a dome-like Shape or a cylindrical shape is built. These ingredients can then be joined together to make a closed To produce tank.

In In one embodiment, the starting material and hence the TiAl6V4 titanium alloy component. The Composition of this alloy is 6 weight percent aluminum, 4 Weight percent vanadium, balance titanium.

When Energy beam can be one or more laser beams or Electron beams or an arc can be used.

Of the Starting material can be used in the form of a wire or a powder become. However, some metallic powders have the disadvantage that they are flammable and / or toxic, so they only under strict controlled conditions can be used. By the use of a wire as a starting material can Difficulties encountered with the use of metallic powders be avoided. A metal in wire form is not only simpler to handle, but usually also cheaper, since its production is also easier.

In An exemplary embodiment is a metallic substrate provided on which the component is built. This metallic one Substrate can form part of the finished fuel cup. in In another embodiment, the component built on a subcarrier, which later removed becomes.

moreover can the source material before or during of the generative manufacturing process further admixtures metallic or non-metallic, e.g. Ceramic materials, z. B. may be added as a powder.

To the Melting of the starting material is a variety of possibilities given. Usually, this is done by one or more Laser beams, electron beams or an arc. It can but also a chemical, exothermic reaction can be used, or the starting material is heated capacitively or inductively. Also any combination of these different heat sources is possible.

In terms of The achievable material properties takes place in one embodiment the process of the invention, the cooling of the molten starting material at a cooling rate in the temperature interval Tliquidus - T450 ° C, the greater than 100 K / sec. Although such cooling rates are intrinsically inherent in the generative process, can for Achieving higher cooling rates an additional Cooling can be used.

moreover it is advantageous if the solidification and cooling of the molten starting material under inert gas or in a vacuum takes place. The shielding gas may, for example, argon, nitrogen or be a mixture of argon and helium.

Even though usually not required, can the generative manufacturing process Downstream heat treatment the material properties improve the manufactured structural component even more and in particular increase the strength and toughness. The subsequent Heat treatment can typically be done at temperatures between 400 ° C and 1200 ° C for a period of 10 minutes to 100 hours respectively.

Of Further, the component after the subsequent heat treatment rapid cooling (eg quenching in water) Room temperature with a subsequent heat aging in the temperature range 400 ° C-650 ° C for be subjected to a period of 10 minutes to 100 hours.

The use of a generative manufacturing method for producing a thin-walled tank, such as a titanium or titanium alloy fuel tank, has the further advantages of:
The generative process allows the production of components of different shapes with the same device. Consequently, all or many of the components of a fuel tank can be manufactured in one place. This avoids the problems of irregular delivery from multiple different suppliers as well as inappropriate parts sourced from different suppliers. The production chain of the fuel tank can thus be downsized.

Further may change due to the generative manufacturing process to be performed on the tank geometries simply because only the computer program, the energy beam and the source material controls, needs to be changed. The generative manufacturing process thus allows a design flexibility that other manufacturing processes such as casting not to offer.

Further the material usage is lower because the layered built Component made with almost the desired dimensions is, the so-called nearnet shape.

embodiments The invention will now be explained in more detail with reference to the drawings.

1 shows a schematic representation of the layered structure of a component of a fuel tank shell according to a first embodiment,

2 shows a schematic representation of the layered structure of a component of a fuel tank shell according to a second embodiment,

3 shows a schematic representation of the further processing of the component of 2 go berserk,

4 shows a schematic representation of the welding of the components of 1 and 3 together.

1 shows a schematic illustration for explaining the layered structure of a dome-like component 1 a fuel tank for a satellite. The part 1 provides a structural component of the tank shell and thus has a hollow shape, which is defined by a thin wall.

The part 1 is built up of a titanium alloy, in particular TiAl6V4, by a generative process in the direction of arrow A in layers. The individual layers 3 are with dashed lines 2 shown in the drawing. The individual layers 3 However, they are not recognizable in the finished tank.

For producing a first layer 3 becomes a starting material 4 made of TiAl6V4 on a surface to be built up 5 applied and with a focused laser beam 6 locally melted as an energy source. The molten area is denoted by the reference numeral 7 designated. The areas 8th of the ingredient 1 that melted outside this area 7 remain unmelted because of the laser beam 6 not on these areas 8th is directed, so that in these areas the temperature below the melting temperature of the starting material 4 remains.

In the first embodiment of the invention, a starting material 4 in the form of a wire 9 made of TiAl6V4, with the end of the wire 9 on the surface to be built up 5 brought and with the laser beam 6 is melted there.

The laser beam 6 as well as the wire 9 are guided in a plane B, which is perpendicular to the construction direction A, to a layer 3 of the ingredient 1 manufacture. In particular, the laser beam 6 as well as the wire 9 in a circle, with the end of the wire 9 in the molten area 7 to be led. This movement of the laser beam 6 and the wire 9 is with the arrows B in 1 shown. The movement of the laser beam 6 as well as the wire 9 is controlled by a computer program.

The molten material solidifies quickly when the laser beam 5 from this molten area 7 in the plane B is controlled away. This creates a solid area 10 a circular layer 3 of the dome component 1 , In this embodiment, the dome-like component 1 When assembled, a wall thickness of about 3 mm (millimeters) on.

To make the next layer of the ingredient 1 become the laser beam 6 as well as the wire 9 Guided so that they are on the surface 11 the previously prepared layer 3 hit and again in a circle with a slightly larger diameter than the underlying layer 3 in a plane B, which is perpendicular to the mounting direction A, are performed. Other layers are similarly made to the component 1 build up layer by layer or layer by layer in the direction of arrow A until it has the desired contour.

In the 1 first the closed ground 12 of the dome component 1 produced. However, it is also possible to start the dome-like shape at the open edge and build the dome-like shape inwardly, with the dome cap then being made.

The 2 shows a schematic representation of another cylindrical component 13 the fuel tank shell according to a second embodiment of the invention. The same components are shown with the same reference numerals and will not be explained further.

The part 13 is also built up layer by layer using a generative manufacturing process. The second embodiment differs from the first embodiment in the shape of the starting material 4 , In the second embodiment, the starting material 4 in the form of a powder 15 provided, which consists of a titanium alloy, in particular TIAl6V4.

A starting powder layer 14 will be on the surface 4 a carrier plate applied. The focused laser beam 6 is applied to the starting powder layer 14 to a place to be built up 5 directed, being a local area 7 the starting powder layer 14 is melted. The laser beam 6 is guided in the plane B in a circle, so that a first solid circular layer 3 will be produced.

Another layer 14 ' gets out of the starting powder 14 on the carrier plate and the first layer 3 applied and the laser beam 6 will be on the surface 11 the other starting powder layer 14 ' directed and guided so that another circular layer 3 ' on the lower layer 3 will be produced. This process is repeated and the component 13 is built up layer by layer in the direction of arrow A to the cylindrical component 13 produce with the desired height.

generative Manufacturing processes can be used to ingredients produce with the desired final contour. In one embodiment However, the ingredients are after the layered construction process further processed.

In this embodiment, the components are heat-treated to increase the mechanical strength. In particular, the ingredients are hot isostatically pressed. Thereafter, the shape and size of the components are refined by twisting and / or grinding in order to improve the dimensional tolerances and / or the surface quality. The twisting of the outer surface 17 of the cylindrical component 13 the tank shell is with the arrows 16 in 3 shown. In this step, the wall thickness is reduced from 3 mm to about 1 mm.

To manufacture the fuel tank, the individual components are joined together. 4 shows a schematic representation of the welded together cylindrical component 13 with the dome-shaped component 1 to a closed pipe 18 manufacture. The weld between the components is with the dashed line 19 shown. In another step, not shown, a second dome-shaped component is attached to the open end of the tube 18 of the 4 welded to produce a closed fuel tank. Holes through the tank shell are also made to fill the tank with fuel and guide the fuel to the engine.

By the use of a generative manufacturing process for manufacturing The components of the fuel tank can be a thin-walled fuel tank made of titanium or a titanium alloy reliably become. Furthermore, components of various shapes produced by the same method and consequently in the same factory become. Together with the generative process this has the advantage that changed the design of the fuel tank in the short term can be. Furthermore, special production of tanks, d. H. Tanks of special size, the usual Standard deviate, by reprogramming the computer-controlled Laser beam and the starting material.

LIST OF REFERENCE NUMBERS

1

dome-shaped component

2

layer boundary

3

layer

4

Starting material

5

be established surface

6

laser beam

7

melted Area

8th

solid Area

9

wire

10

solid Area

11

be established surface

12

Domboden

13

cylindrical component

14

Starting powder layer

15

powder

16

turn

17

outer surface

18

closed pipe

19

Weld

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007014948 A1 [0005]

Claims (24)

Use of a generative manufacturing process for the layered construction of at least one constituent ( 1 ; 13 ) a tank shell of a tank for liquids and / or gases, the component ( 1 ; 13 ) consists of titanium or a titanium alloy. Use of the generative manufacturing process according to claim 1, wherein the tank is a fuel tank of a satellite is. Use of the generative manufacturing process according to claim 1, wherein the tank is a fuel tank of an aircraft or a vehicle or a space shuttle. Method for producing a fuel tank, wherein - at least one component ( 1 ; 13 ) of a tank shell of the tank is built up in layers by a generative manufacturing process, the component ( 1 ; 13 ) is made of titanium or a titanium alloy and has a hollow shape which is defined by a wall with a wall thickness, - after the layered structure of the component ( 1 ; 13 ) the part ( 1 ; 13 ) is further processed to give the final dimensions of the constituent ( 1 ; 13 ) to create. A method according to claim 4, characterized in that the layered structure of the component ( 1 ; 13 ) an energy beam ( 6 ) on a surface to be built up ( 5 ), on which a starting material ( 4 ) made of titanium or a titanium alloy, wherein a molten area ( 7 ) from the starting material ( 4 ) on the surface to be built up ( 5 ) with the energy beam ( 6 ), and the energy beam ( 6 ) above the surface to be built up ( 5 ) is defined to be a layer ( 3 ) of the component ( 1 . 13 ). Method according to claim 4 or claim 5, characterized in that the wall thickness of the component ( 1 ; 13 ) is between 2 mm and 10 mm, preferably between 3 mm and 5 mm. Method according to one of claims 4 to 6, characterized in that the energy beam ( 6 ) defined so that the constituent ( 1 ; 13 ) in a dome-like shape ( 1 ) or a cylindrical shape ( 13 ) is constructed. Method according to one of claims 4 to 7, characterized in that the starting material ( 4 ) consists of TiAl6V4. Method according to one of claims 4 to 8, characterized in that as energy beam ( 6 ) one or more laser beams or electron beams or an arc are used. Method according to one of claims 4 to 9, characterized in that a wire-shaped starting material ( 9 ) is used. Method according to one of claims 4 to 9, characterized in that a powdered starting material ( 15 ) is used. Method according to one of claims 4 to 11, characterized in that the starting material ( 4 ) before or during the process further admixtures of metallic or non-metallic materials are added. Method according to one of claims 4 to 12, characterized in that for melting the starting material ( 4 ) a chemical exothermic reaction is used. Method according to one of claims 4 to 12, characterized in that the starting material ( 4 ) is heated capacitively, ohmically or inductively. Method according to one of claims 4 to 14, characterized in that a cooling of the molten starting material ( 4 ) in the temperature interval Tliquidus - T450 ° C with a cooling rate greater than 100 K / sec. A method according to claim 15, characterized in that the cooling rate of the molten starting material ( 4 ) is increased by an additional cooling. Method according to one of claims 4 to 16, characterized in that the solidification and cooling of the molten starting material ( 4 ) takes place under inert gas or in vacuo. Method according to one of claims 4 to 17, characterized in that for further processing of the component ( 1 ; 13 ) the part ( 1 ; 13 ) is turned off or ground. Method according to one of claims 4 to 18, characterized in that the constituent ( 1 ) with another component ( 13 ) is welded from titanium or a titanium alloy. Method according to one of claims 4 to 19, characterized in that the from the starting material ( 4 ) component ( 1 ; 13 ) a subsequent heat treatment at temperatures between 400 ° C and 1200 ° C for a period of 10 min to 100 h. Method according to claim 21, characterized that the subsequent heat treatment in several Steps and / or steps is performed. Method according to claim 20 or 21, characterized in that the constituent ( 1 ; 13 ) after the subsequent heat treatment of a rapid cooling to room temperature. Method according to claim 22, characterized in that that after the rapid cooling another heat Auslagerung in the temperature range 400 ° C-650 ° C for a duration of 10 minutes to 100 hours. Method according to one of claims 4 to 23, characterized in that the from the starting material ( 4 ) component ( 1 ; 13 ) is hot isostatically pressed.

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