DE102021105992A1 - Method for producing a molded part - Google Patents

Abstract

The invention relates to a method for producing a molded component (1) comprising the steps of: producing a molding tool (3) by means of an additive manufacturing process from a first powder with metallic powder particles for the production of the molded component (1), the molding tool (3) at least one outer edge contour (4) of the molded component (1) and at least one open volume (5), which is surrounded by the edge contour (4), and is left on the finished molded component (1), filling the open volume (5) with a further powder with metallic powder particles (7), the molding tool (3) being designed to be completely open on at least one side and the further powder being pressed into the molding tool (3) with a ram (11) into the open volume (5).

Description

The invention relates to a method for producing a molded component comprising the steps of: producing a molding tool by means of an additive manufacturing process from a first powder with metallic powder particles for the production of the molded component, wherein the molding tool has at least one outer edge contour of the molded component and at least one open volume, which is from the edge contour is surrounded, forms, and is left on the finished molded component, filling the open volume with a further powder with metallic powder particles.

Sintering technology has established itself in the automotive supply industry for the large-scale production of components with complex geometry. In addition, processes have always been described that are known under the term additive manufacturing processes. To put it simply, it is essentially a 3D printing process. Originally only used for prototype production, these processes are now also finding their way into small series production.

• - Herstellen eines Körpers aus einem ersten pulverförmigen Material mittels metallischem 3D-Druck, insbesondere Binderjetting, welcher zumindest teilweise eine Hohlstruktur aufweist, wobei der Körper zumindest eine Öffnung in der Hohlstruktur aufweist;
• - Entfernen des überschüssigen ersten pulverförmigen Materials aus der Hohlstruktur des Körpers über die zumindest eine Öffnung in der Hohlstruktur und anschließend entweder:
• - Auffüllen der Hohlstruktur des Körpers mit einem zweiten pulverförmigen Material; Nachverdichten des zweiten pulverförmigen Materials mittels einer Rüttelvorrichtung; Entfernen von Zusatzmittel, welches während des metallischen 3D-Drucks eingesetzt wird; Sintern des Körpers aus erstem Material mit dem pulverförmigen zweiten Material, sodass das dreidimensionale Bauteil hergestellt wird; Entnahme des fertigen dreidimensionalen Bauteils; oder
• - Entfernen von Zusatzmittel, welches während des metallischen 3D-Drucks eingesetzt wird; Sintern des Körpers aus erstem Material mit einer ersten Sintereinstellung; Auffüllen der Hohlstruktur des Körpers mit einem zweiten pulverförmigen Material; Nachverdichten des zweiten Materials mittels einer Rüttelvorrichtung; Sintern des Köpers aus erstem Material mit dem pulverförmigen zweiten Material mit einer zweiten Sintereinstellung, so dass das dreidimensionale Bauteil hergestellt wird; Entnahme des fertigen dreidimensionalen Bauteils.

From the DE 10 2018 203 151 A1 a method for producing a three-dimensional component is known. The procedure consists of the following steps:

• - Production of a body from a first powdery material by means of metallic 3D printing, in particular binder jetting, which at least partially has a hollow structure, the body having at least one opening in the hollow structure;
• - Removal of the excess first powdery material from the hollow structure of the body via the at least one opening in the hollow structure and then either:
• - Filling the hollow structure of the body with a second powdery material; Re-compacting the second pulverulent material by means of a vibrating device; Removal of additives used during metallic 3D printing; Sintering the body made of the first material with the powdery second material, so that the three-dimensional component is produced; Removal of the finished three-dimensional component; or
• - Removal of additives that are used during metallic 3D printing; Sintering the body of first material with a first sintering setting; Filling the hollow structure of the body with a second powdery material; Re-compacting the second material by means of a vibrating device; Sintering the body made of the first material with the powdery second material with a second sintering setting, so that the three-dimensional component is produced; Removal of the finished three-dimensional component.

The essence of this process is therefore to produce a component according to the shell-core principle, as stated in this publication.

The object of the invention is to provide a method for producing a molded component from powders which has great variability with regard to the shape of the molded component to be produced and with which the molded components can be produced more cost-effectively than conventional sintered components.

The object is achieved with the mold component mentioned at the beginning, in which it is provided that the mold is designed to be completely open at least on one side, and that the further powder is pressed into the mold by means of a press into the open volume.

The advantage here is that a separate mold for powder-metallurgical production does not have to be produced for each molded component in accordance with classic mold construction. A molded component can therefore also be produced in a small or very small series or as a special component, since only the data of the mold need to be provided for the production of the molding tool (in addition to the otherwise usual process parameters for controlling the machine during the production of the molding tool, which as a rule always remain at least essentially the same). The advantage here is that the molding tool is minimized as much as possible, i.e. that at least one molding surface is completely missing. In essence, the molding tool can only be produced defining the circumferential contour of the molded component. This means that the powder can be poured into the open volume defined by the molding tool more quickly. In addition, conventional machines, such as presses with filling shoes, can also be used to fill the mold. This means that the process can be better integrated into conventional powder metallurgical processes. As a result of the use of presses, not only can the powder be compacted more quickly, but a higher level of compaction can also be achieved than, for example, with ultrasonic compressors. In addition, no special powders have to be used to achieve higher densities, which means that the manufacturing costs of the molded component can be additionally reduced. By achieving a higher green density, a reduction in the sintering temperature and the sintering time is possible if the filling is sintered from the further powder.

According to one embodiment of the invention, it can be provided that the molding tool is designed in the shape of a shell. In this way, not only is the circumferential contour of the molded component defined by the molding tool, but the molding tool also has a base which simplifies the filling of the open volume.

According to a further embodiment variant of the invention, it can be provided that the open volume is divided into several partial volumes by means of a support structure. On the one hand, the molding tool can thus be designed with a smaller wall thickness or the molded component can be given a higher mechanical stability. On the other hand, it is also more easily possible to specifically provide areas in the molded component which have different properties from the rest of the molded component.

According to a further embodiment variant of the invention, a support structure that is embodied as spoke-shaped or honeycomb-shaped or network-shaped or lattice-shaped has proven to be particularly suitable for achieving or reinforcing these effects.

According to another embodiment variant of the invention, it can also be provided that the molding tool also forms an inner edge contour of the molded component, for example an inner circumference. In this way, for example, at least approximately hollow cylindrical shaped components, such as gear wheels, can be produced relatively easily, with the inner circumferential surface being given a higher mechanical stability against wear through the use of a suitable first powder, in particular the metallic powder particles. A higher mechanical stability against wear can also be achieved by printing the internal structure as a fully dense material and in particular having a higher density than a powder metallurgical component.

In order to achieve even higher densities in the molded component, it can be provided according to an embodiment variant of the invention that the further powder filled into the open volume is further compressed in a further compression step. The large-area accessibility of the powder filling from the further powder has an advantageous effect here, since the redensification can thus take place more easily and in a shorter time. It is also possible to specifically provide areas with a higher density in the component.

As already stated above, according to an embodiment variant of the invention it can be provided that the molded component is sintered or the further powder filled into the open volume is melted or melted. When using a powder with a lower melting point than that of the mold, this can serve as a mold for the liquid melt.

According to a further embodiment of the invention it can be provided that the same powder or powder with different properties are used as the first powder and as the further powder, so that molded components with a wide variety of properties can be produced relatively easily or a desired profile of properties of the molded component can be produced relatively easily.

For the same reasons, it can be provided according to an embodiment of the invention that the open volume is filled with different powders.

According to another embodiment of the invention, it can be provided that the open volume is filled with a liquid instead of or in addition to the further powder, and this liquid is hardened after filling, whereby the properties of the molded part can be varied to a greater extent.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

• 1 ein Formbauteil im Querschnitt;
• 2 einen Herstellungsschritt für einen Formbauteil;
• 3 ein Formwerkzeug zur Herstellung eines Formbauteils;
• 4 eine Ausführungsvariante eines Formwerkzeugs zur Herstellung eines Formbauteils.

They each show in a greatly simplified, schematic representation:

• 1 a shaped component in cross section;
• 2 a manufacturing step for a molded component;
• 3 a molding tool for producing a molded component;
• 4th a variant of a molding tool for producing a molded part.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference symbols or the same component designations, it being possible for the disclosures contained in the entire description to be transferred accordingly to the same parts with the same reference symbols or the same component designations. The position details selected in the description, such as above, below, to the side, etc., also relate to the figure immediately described and shown and these position details are to be transferred accordingly to the new position in the event of a change in position.

Information on standards in this description always refers to the latest version of the patent application in question on the filing date of the respective standard, unless expressly stated otherwise.

1 shows a molded component 1 . The molded part 1 comprises a three-dimensional component body 2 .

The component body 2 preferably comprises or consists of at least one metallic material. But it is also possible for the component body 2 at least partially use a different material, such as a polymer plastic. It is also possible that the molded part 1 consists of or has at least two different metallic materials or polymer plastics or elastomers.

The molded part 1 after 1 is only to be understood as an example for various specific component shapes in order to be able to represent the essence of the invention. The molded part 1 can for example be a gear wheel, a sliding sleeve, a synchronizer ring, a connecting rod, a bearing cover for a split bearing arrangement, a bearing element, an unbalanced component, a torsional vibration damper, a filter structure or other components according to the benefits of the properties provided by this method.

The molded part 1 has a molding tool 3 that surrounds a volume that is filled with another material, or consists of these components.

The molding tool 3 is used for each molded part 1 manufactured separately because it is attached to the molded part 1 remains, so to a part of the molded part 1 will.

The molding tool 3 is manufactured using an additive manufacturing process. For example, the component 1 can be produced using any of the previously known additive processes such as Laser Powder Bed Fusion, Electron-Beam Powder Bed Fusion, Selective Laser Sintering, Binder Jetting, Direct Energy Deposition, Wire Arc Additive Manufacturing, Fused Depostion Molding, Stereolithography process and other processes.

Since these methods are known per se, reference is made to the relevant prior art (to avoid repetitions) for further details.

For the production of the at least partially, preferably completely, metallic three-dimensional molded component 1 becomes the molding tool first 3 manufactured. For this purpose, this is produced from at least one first powder with or from metallic powder particles. Ceramic powder particles can also be contained in the first powder, for example.

The first powder is processed using a conventional device (in particular a 3D printer) for the additive manufacturing of components. This device has at least one data memory or at least one data memory is assigned to this device for operation. A first data set (CAD data) for the production of the molded component is stored in this at least one data memory 1 provided. This data record includes data relating to the geometry.

A second data record with process parameters for controlling the device is also provided in this data memory. The process parameters are used to define, for example, the printing speed or the speed at which the individual layers are formed.

By processing the individual program steps with which the device is operated, the individual layers are used to build the mold 3 successively produced one above the other or the molding tool in general 3 manufactured.

With a device for the introduction of energy into the respectively deposited layer, the powder particles of the first powder are connected within a layer and with the layer immediately below, in particular in that the powder particles are at least superficially melted or sintered together.

For the production of the molding tool 3 can be non-spherical powder particles 5 can be used, for example a so-called water-atomized powder. However, gas-atomized powders with at least approximately spherical powder particles can also be used.

In principle, the first powder used can have powder particles of the most varied of sizes. According to a preferred embodiment of the invention, however, powders are used, the powder particles 5 of grain fractions according to DIN ISO 4497 in the range of 0 µm - 250 µm.

The first powder can be a pure metal powder or an alloy powder or a powder mixture of different metallic powders (pure metals and / or alloys). For example, the powder can be an iron powder or an iron alloy powder or an aluminum powder or an aluminum alloy powder or a titanium powder or a titanium alloy powder or a copper powder or a copper alloy powder, or else mixtures thereof.

How out 1 can be seen, forms the mold 3 at least one outer edge contour 4th of the molded part 1 . This is also in 2 indicated by dashed lines. That is to say that the molding tool is the circumferential surface, that is to say, for example, a lateral surface, of the molded component 1 defined after the forming tool 3 on the finished molded part 1 remains. Further defines the forming tool 3 at least one open volume 5 how this looks 2 can be seen. The open volume 5 is surrounded by the edge contour.

The edge contour of the molded part 1 , i.e. the molding tool 3 can have a wall thickness 6th between 0.3 mm and 30 mm. The wall thickness 6th can be designed to be the same everywhere or differently in areas or sections. For example, the wall thickness 6th of the molding tool 3 in particularly stressed areas of the molded part 1 be larger than in the rest of the molded part 1 . The wall thickness can also 6th of the molding tool 3 in particularly stressed areas of the mold 3 during the manufacture of the molded part 1 be larger than the rest of the mold 3 .

The molding tool 1 can thus for example have an at least approximately ring-shaped geometry in the simplest case.

After the molding tool 3 is established, becomes the open volume 5 with a further powder with metallic and / or ceramic powder particles 7th filled, in particular completely filled like this out 2 can be seen. With "completely filled up" is meant that in the finished molded component 1 the filling of the further powder in alignment with one end face 8th of the molding tool 3 concludes. However, other degrees of filling are also possible. For example, the filling can be made from the further powder in predefinable areas with at least one cutout 9 or at least one recess can be produced, as shown in FIG 1 is indicated by dashed lines. In the 1 The form shown in concrete terms is only illustrative and not restrictive. It is particularly advantageous if the open volume is filled with the powder via the upper edge of the molding tool, since a simple plate press can then be used to press into the molding tool. Repeated pressing and refilling is also possible. Different powder materials can be filled and pressed (compacted) alternately.

Filling the open volume 5 can be carried out in one step or in several steps, optionally with an intermediate compression of the further powder.

Filling the open volume 5 with the further powder can with conventional devices, such as a so-called filling shoe, which over the open volume 5 is spent and from which the necessary amount of additional powder is released. The further powder can, however, also be introduced into the open volume (by hand) from a corresponding vessel.

This simple filling of the molding tool is made possible 3 in that this is designed to be completely open at least on one side, as shown in the 1 and 2 can be seen. The molding tool is thus without a top surface with which the open volume 5 could be covered, manufactured. A filling opening 10 thus has a size which corresponds to the size of the area which is defined by the inner edge (s) of the end face (s) 8 or is limited by this / these.

This volume, which is completely open at least on one side 5 of the molding tool 3 further enables the simple and rapid removal of any excess first powder from the molding tool 3 (before this is filled with the further powder).

In addition, the large open volume enables it 5 also the use of presses to compact the further powder. So it can, for example, presses with a ram 11 are used, which are known from sintering technology for the production of green compacts, as described in 2 is indicated. The ram 11 also has a size of the pressing surface that is that of the filling opening 10 corresponds, taking into account that the ram 11 according to the double arrow shown in 2 possibly in the mold 3 should be able to immerse, so between the by the edge contour 4th defined "mold wall" of the mold 3 and the ram 11 a (slight) gap remains. The ram 11 but can also have an area larger than the pressing surface of the molding tool 3 exhibit. As a result, the press ram cannot enter the molding tool 3 immerse, but it can be caused by overfilling with powder over the upper edge of the mold 3 In addition, any form tools with the same press punch 11 or flat ram are pressed, with which a virtually tool-free production can be made possible.

By using the press ram 11 the further powder can quickly and easily be poured into the open volume 5 be pressed in and compressed. If necessary, the compression can be repeated several times, especially if the open volume 5 is filled in several steps (if necessary with different powders).

If necessary, the molding tool 3 when compacting with the ram 11 be supported from the outside, for example to enable higher pressing pressures.

As already mentioned above, the molding tool 3 in the simplest case be designed in a ring shape. In this case it is during the filling of the open volume 5 a support is required, for example in the form of a lower punch of the press, with which the further powder is compacted. But it is also possible that the molding tool 3 is printed directly onto the metallic construction platform using an additive process (3D printing) and this construction platform is used directly as the base of the printed contour of the molding tool. The building platform can therefore be the bottom of the molding tool produced 3 form. The powder goes straight into the mold 3 pressed and only then separated from the build platform.

According to one embodiment of the invention, however, it can also be provided that the molding tool 3 is at least approximately cup-shaped. The bowl-shaped design is off 2 evident.

It should be pointed out in this connection that the annular side wall does not run perpendicular to a floor 12th of the bowl-shaped mold 3 must be formed, but also at an angle other than 90 ° to the ground 12th can run. The floor has to go further 12th not necessarily be designed flat, as shown in 2 is shown. The floor 12th can also have a shape deviating from flatness.

Even with the shell-shaped design of the molding tool 3 the above-mentioned construction platform can be used as a support.

According to a further embodiment of the invention it can be provided that the open volume 5 in several partial volumes 13th is divided. This can be done like this in the 3 and 4th is shown, according to a further embodiment of the invention in the open volume 5 of the molding tool 3 a support structure 14th are formed as above by means of an additive manufacturing process. The support structure 14th can be made, for example, spoke-shaped or honeycomb-shaped or net-shaped or lattice-shaped, but can also have a different shape, for example in the form of rings (arranged concentrically to one another), etc.

By providing the support structure 14th can, among other things, the partial volumes 13th easier to fill with different materials, especially different powders. With regard to further advantages of this embodiment variant, reference is made to the statements above.

But it is also possible to use the open volume 5 to be filled with different powders when the molding tool 3 no support structure 14th having.

Next are in 3 teeth 15th a toothing of a gear indicated. As already stated, the molded component 1 also be a gear.

Just to clarify that the molding tool 1 can have a wide variety of forms are in the 3 and 4th a molding tool which is at least approximately cylindrical in plan view 3 with a circular cross-section or a molding tool 3 shown with an octagonal cross-section. However, these forms are not of a restrictive nature for the invention.

Next is off 3 can be seen that the molding tool 3 according to a further embodiment of the invention, also an inner edge contour 16 of the molded part 1 can form. It is thus possible to use the molded part 1 with one in the axial direction through the molded component 1 to provide penetrating breakthrough, so that the molded part 1 can be attached to another component, for example a shaft or an axle.

As also already stated above, according to a further embodiment variant of the invention it can be provided that the further powder filled into the open volume is further compressed in a further compression step. The further compression step can also be carried out with the at least one press ram 11 be performed. However, it is also possible to use other compression methods as an alternative or in addition, for example to effect additional compression with ultrasound.

In this context it should be mentioned that the ram 11 can have a surface contour / a surface pattern on its pressing surface, for example around the recess mentioned above 9 in the molded part 1 to create.

In the preferred embodiment of the invention, the molded component 1 sintered or the further powder filled into the open volume is melted or partially melted. The molded part 1 can in this case also be referred to as a molded sintered component. In general, the molded component can also be used as a hybrid component from additive and powder metallurgical production or as a contour component or are referred to as the shell component. The sintering itself can (depending on the powders used and / or the pretreatment of the molded part 1 ) for example at a temperature between 500 ° C and 1600 ° C for a period of time between five minutes and two hours.

When sintering or at least partially melting the filling of the molding tool 3 can not just connect the powder particles 7th be produced with each other, it can optionally also the powder filling of the mold 3 be connected to this.

The further powder can be a pure metal powder, a mixture of pure metal powders, an alloy powder or a mixture of alloy powders, such as pure iron or low-alloy iron powder, copper and copper alloys, aluminum and aluminum alloys and mixtures of these with ceramic particles such as tungsten carbide, aluminum oxide, aluminum nitride, Titanium dioxide, titanium nitride, titanium carbide, silicon oxide, silicon nitride, silicon carbide, etc.

It is possible that the first powder and the second powder are different powders. In general, the first powder and the further powder with different properties can be used. "Different properties" does not necessarily mean a different composition of the powder. The other properties can also be due to a different shape and / or size of the particles in the powder.

However, it can also be provided that the same powder is used as the first powder and as the further powder.

In this context it should be pointed out that the powders, in particular the further powder, can also be provided with auxiliaries, such as, for example, pressing auxiliaries, etc. These auxiliaries are known from sintering technology, so that further explanations are unnecessary.

According to a further embodiment variant, it can also be provided that the open volume 5 is filled with several different powders, so that for the production of the molded part 1 in this case at least three different (metallic) powder (mixtures) are used.

In addition, according to a further embodiment of the invention, it is possible that the open volume 5 instead of or in addition to the further powder is filled with a liquid, and this liquid is hardened after the filling. The liquid can be based on epoxy hairs, acrylates, urethanes, rubber prepolymers, etc., for example. It is also possible to fill the open volume using an injection molding process with thermoplastics such as PE, PP, PA, PS, TPU or similar.

Any hardening or hardening that may be required can be carried out thermally or by irradiation (e.g. with UV light).

The exemplary embodiments show possible design variants, whereby it should be noted at this point that combinations of the individual design variants with one another are also possible.

Furthermore, parts of the invention can be an independent invention. For example, a described molded component 1 be a standalone invention if its filling the mold 3 has a density of at least the bulk density of the powdery material determined in accordance with DIN ISO 3923. For example, molten iron has a density of 7.85 g / cm ³ . The bulk density of iron powder is approx. 3 g / cm ³ (depending on the powder particle size distribution.

The further powder can be a plastic, glass, ceramic or metal powder and any combination thereof.

The liquid mentioned above can be a solution, a suspension, a dispersion or an emulsion. Pastes, such as a slip composed of metallic and / or ceramic particles, or foams or the precursors to foams can also form the liquid in the context of the invention.

For the sake of order, it should finally be pointed out that for a better understanding of the structure of the molded part 1 or the molding tool 3 these are not necessarily shown to scale.

List of reference symbols

1

Molded part

2

Component body

3rd

Forming tool

4th

Edge contour

5

volume

6th

Wall thickness

7th

Powder particles

8th

Face

9

Recess

10

Filling opening

11

Press ram

12th

floor

13th

Partial volume

14th

Support structure

15th

tooth

16

Edge contour

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102018203151 A1 [0003]

Claims (10)

A method for producing a molded component (1) comprising the steps: - producing a molding tool (3) by means of an additive manufacturing process from a first powder with metallic powder particles for the production of the molded component (1), - wherein the molding tool (3) has at least one outer edge contour (4) of the molded component (1) and at least one open volume (5) which is surrounded by the edge contour (4) and is left on the finished molded component (1), - Filling the open volume (5) with another Powder with metallic powder particles (7), characterized in that the molding tool (3) is designed to be completely open at least on one side and that the further powder is pressed into the molding tool (3) with a ram (11) into the open volume (5) . Procedure according to Claim 1 , characterized in that the molding tool (3) is designed in the shape of a shell. Procedure according to Claim 1 or 2 , characterized in that the open volume (5) is divided into several partial volumes (13) with a support structure (14). Procedure according to Claim 3 , characterized in that the support structure (14) is formed spoke-shaped or honeycomb-shaped or net-shaped or lattice-shaped. Method according to one of the Claims 1 until 4th , characterized in that the molding tool (3) also forms an inner edge contour (16) of the molded component (1). Method according to one of the Claims 1 until 5 , characterized in that the further powder filled into the open volume (5) is further compressed in a further compression step. Method according to one of the Claims 1 until 6th , characterized in that the molded component (1) is sintered or the further powder filled into the open volume (5) is melted or melted. Method according to one of the Claims 1 until 7th , characterized in that the same powder or powder with different properties are used as the first powder and as the further powder. Method according to one of the Claims 1 until 8th , characterized in that the open volume (5) is filled with different powders. Method according to one of the Claims 1 until 9 , characterized in that the open volume (5) is filled with a liquid instead of or in addition to the further powder, and this liquid is hardened after filling.

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