DE102018122296A1 - Method and device for additive manufacturing of a component with a support structure - Google Patents

Abstract

The invention relates to a method for the additive manufacturing of a component (3, 3 ') with a predetermined outer contour within an image box (1) which serves to delimit a construction field, comprising the steps:
a) applying a layer of a powdery material,
b) selective solidification of the powdery material based on construction data of the layer,
c) repeating steps a) and b) until the application and selective solidification of all layers required for additive manufacturing of the component (3, 3 '), as well as a device for the additive manufacturing of a additively manufactured component (3, 3').
The object of providing a method and a device for additive manufacturing of a component, in which an inaccuracy in the additive manufacturing of the component due to an unwanted movement of the powdered material applied is prevented or at least reduced, is achieved in that a support structure ( 4) is produced in addition to the component (3, 3 '), the support structure (4) covering the area between the image box (1) and the outer contours of the component (3, 3') without contact with the component (3, 3 ') to be produced runs through.

Description

The invention relates to a method for additive manufacturing of a component with a support structure according to the preamble of claim 1 and a device for the additive manufacturing of a additively manufactured component comprising a support structure according to the preamble of claim 11.

Numerous methods for additive or additive manufacturing of components are known from the prior art, such as powder bed processes or liquid material processes. With some methods it is necessary to use support structures in the manufacture of the component in order to support the additively manufactured component. In particular in the case of liquid material processes, such as, for example, stereolithography, support structures are required in order to support overhangs of components, as a result of which the regions of the component are kept in the desired geometric assignment.

From the German patent application DE 199 54 891 A1 For example, a stereolithography process emerges in which a supporting framework is produced together with the component to be produced in successive layers. The support frame serves to support predetermined areas of the component, in particular overhanging areas. For this purpose, the component and the supporting structure are connected to one another via needle-like posts. In order to separate the support structure from the component, a corresponding post-processing step is usually required.

In powder bed processes, a powdery material or granulate is applied in layers and then selectively solidified. Binder jetting, selective laser sintering, selective laser melting and electron beam melting are known from the prior art as powder bed processes. In the case of binder jetting, the powdery material is glued with a binder at selected points and thus solidified. In the case of selective laser sintering and selective laser melting, on the other hand, the powdery material is solidified with the aid of a laser and in the case of electron beam melting with the aid of an electron beam. Since the powdered material applied already provides sufficient support for the component, additional support structures are not required in powder bed processes. However, with powder bed processes it could be observed that an unwanted movement of the already applied, not solidified powder material causes inaccuracies in the layer-by-layer, generative manufacture of the component. Individual particles can move, for example, into existing interstices not filled with the powdery material. In particular, doctoring or shaking, in which a newly applied layer of the powder material is smoothed, often causes the powdery material to move. This is often associated with an unwanted movement of the structures that have already been manufactured. Since the acceptable manufacturing tolerances are often very small, inaccuracies of this kind can lead to high rejects in manufactured components. The inaccuracies resulting from the unwanted movement of the particles of the powdery material are in particular also from the particle size of the powdery material or the granules used and other parameters, such as depending on the environmental conditions and can therefore only be controlled with difficulty.

The object of the invention is to provide a method and a device for additive manufacturing of a component, in which an inaccuracy in the additive manufacturing of the component due to an unwanted movement of the applied powdered material is prevented or at least reduced.

The invention achieves this object by a method having the features of claim 1 and by a device having the features of claim 11. Advantageous refinements and useful developments of the invention are specified in the dependent claims.

1. a) Auftragen einer Schicht eines pulverförmigen Materials,
2. b) Selektive Verfestigung des pulverförmigen Materials basierend auf Konstruktionsdaten der Schicht,
3. c) Wiederholen der Schritte a) und b) bis zur Auftragung und selektiven Verfestigung aller für eine generative Anfertigung des Bauteils erforderlichen Schichten.

The method for additive manufacturing of a component with a predetermined outer contour within an image box serving to delimit a construction field comprises the steps customary in powder bed methods:

1. a) applying a layer of a powdery material,
2. b) selective solidification of the powdery material based on construction data of the layer,
3. c) repeating steps a) and b) until application and selective consolidation of all layers required for additive manufacturing of the component.

The bottom of the picture box is preferably formed by a movable carrier plate which, after the application of a layer or after the selective solidification of the powdery material of a layer, is lowered by one layer thickness each. The powdery material applied can be applied over the entire surface, in particular with the aid of a doctor blade or a roller. According to the invention, the method is characterized in that a support structure is produced in addition to the component within each layer, the support structure covering the area between the image box, specifically between the inner edges of the image box, which delimit the construction field. and runs through the outer contours of the component. The support structure is preferably produced simultaneously with the component and therefore does not require any additional method steps, for example method steps in which a corresponding support structure is introduced from the outside. The design of the support structure in each layer greatly reduces the freedom of movement of the powdered material applied. The support structure contributes significantly to the fact that the powdery material already applied and not solidified is supported within the image box against flowing, slipping or other movements of the particles of the material. Inaccuracies in the additive method due to unwanted movements of the powdery material, which can arise in particular during the application or smoothing of a further layer, are thereby reduced or prevented. Furthermore, the support structure is characterized according to the invention in that it has no contact with the component to be produced, in particular with its outer contour. In the area between the component and the support structure there is an intermediate space with non-solidified or non-bound powdery material. Complex and time-consuming post-processing steps for separating the component from the support structure are therefore not necessary. The space between the component and the support structure can always have the same width around the contour of the component or can vary, in particular depending on the geometric shape of the component. The support structure preferably also has no connection to the image box. The support structure can then be removed from the image box after the component has been produced without any further processing steps. However, it is also conceivable to connect the support structure to the picture box. In particular, this can bring about advantages in terms of production technology and stabilization of the support structure and thereby contribute to additional fixing of the powdery material.

The respective configuration of the support structure adapted to a component to be produced can be generated, for example, by preprogrammed support framework generators based on the construction data of the component and the geometric configuration of the image box. In order to test the accuracy of the additive manufacturing process, test specimens can be made in addition to the component. By measuring the test specimens, a statement can be made about the accuracy or the quality and the manufacturing tolerances of the component without having to measure the component itself. A measurement of the test specimen can also take place during the method in order to be able to intervene in a corrective manner in the event of an error, in particular already during the additive method.

The support structure preferably extends essentially through the entire area of the image box that is not intended for the component. The support structure also has no contact with the component. In particular with special configurations of the component, for example with an undercut or an opening, such as in the case of a ring-shaped component, it is advantageous if, in addition to the region between the image box and the outer contour of the component, the inner region enclosed by the contours of the component is also penetrated by the support structure. The support structure can be easily removed from the image box after the end of the additive manufacturing process, in particular if the component is open or undercut, and the support structure can be eliminated in the process. As a result, the accuracy of the method or of a component resulting therefrom can be further increased, particularly in the area of undercuts and openings.

It is particularly advantageous if the support structure is produced generatively, in particular through the selective solidification of the powdery material. Generative manufacturing makes it possible to easily adapt the geometric design of the support structure individually to the component to be produced, the image box and the powdery material used. The support structure and the component preferably consist of the same material or the same materials. This provides an efficient generative process without additional devices, for example through additional systems for applying or solidifying different powdery materials, and without additional process steps. However, it is also possible to manufacture the component and the support structure from different materials. As a result, the component and support structure can be manufactured with, for example, different mechanical properties, in particular a different strength. It is particularly conceivable to produce the support structure from a material that enables simple reprocessing of the material used for the support structure. For example, this is conceivable through the use of a thermoplastic as a binder for the support structure in binder jetting.

In a preferred embodiment, the support structure has at least partially closed support structure units, for example in the form of closed chambers. The absolute size of a support structure unit can be selected depending on the component geometry, the powder used and / or the size of the image box. The closed support structure units further reduce the freedom of movement of the powdery material in the region of the support structure. This has a positive effect on the accuracy of the process or of structures made by the method. In the area of the component in particular, the support structure can deviate from the closed support structure units. Depending on the geometry of the component to be manufactured, the support structure units can be partially open, for example, or closed by correspondingly adapted connections.

The support structure is particularly preferably a hollow chamber structure. The required stability of the support structure is particularly high. In contrast to a full-volume support structure, this results in a material-saving configuration of the support structure in which the non-consolidated powdery material arranged between the hollow chambers can then be reused. In addition, less time is required for the generative production of the support structure than, for example, in the case of a full-surface configuration of the support structure. In a particularly advantageous embodiment, the support structure has a honeycomb pattern. In particular with regard to their stability, the support structure is particularly advantageous. In addition, the use of a honeycomb pattern is also advantageous when adapting the support structure to the contour of the component. However, support structures with other patterns are also conceivable, for example a pattern that is square or diamond-shaped or octahedral in cross-section.

The support structure is preferably designed as a plurality of plates arranged in parallel and at a distance from one another with chambers between adjacent plates. This further reduces the freedom for unwanted movement of the powdery material, which can occur, for example, by doctoring, shaking or lowering the carrier plate. The accuracy of the method or the resulting component is thus further improved. The plates are preferably arranged parallel to the carrier plate. This also offers the possibility of a continuously ongoing additive manufacturing process. After the application of the last layer of a component to be manufactured, an intermediate plate arranged parallel to the carrier plate can be formed, which serves as the floor for the next component. This provides a particularly efficient embodiment of the generative process, which enables the production of several components in a continuous process.

The solidification of the pulverulent material by a binder in so-called binder jetting is particularly advantageous for the method according to the invention. Selective solidification by laser melting, laser sintering or electron beam melting is also possible. Such methods and their respective advantages are known from the prior art and, in addition to simultaneous manufacture, in particular enable the support structure to be designed in an advantageous manner.

The powdery material is preferably sand or a metal powder or a polymer granulate or a ceramic powder. This enables advantageous manufacture of the components and of the support structure according to the invention. It is possible to use different powdery materials, for example different metal powders, for individual areas. For example, a different powder material can be used for the component than for the support structure in order to obtain different properties of the respective areas.

The invention also includes a device for the additive manufacturing of a additively manufactured component with a predetermined outer contour within an image box which serves to delimit the construction field. The device comprises a support structure that is manufactured in addition to the component and extends over the entire area between the image box and the outer contour without contact with the component to be produced. The advantages of such a device for additive manufacturing correspond to the advantages mentioned above for increasing the accuracy of the method or the resulting component. The configuration of the support structure, the powdery materials used here and the means used for the selective solidification of the powdery material can correspond to the advantageous features and designs mentioned above.

• 1 eine Draufsicht auf eine Schicht eines aufgetragenen und bereichs- bzw. teilweise verfestigten pulverförmigen Materials;
• 2 ein Schnitt durch die Schnittebene A-A aus 1;
• 3 ein Schnitt durch die Schnittebene B-B aus 1;
• 4 eine Draufsicht auf eine Schicht des aufgetragenen und verfestigten pulverförmigen Materials in einem Bereich ohne Bauteil;

Special features and advantages of the invention result from the following description of preferred exemplary embodiments with reference to the drawings. These show:

• 1 a plan view of a layer of an applied and partially or partially solidified powdery material;
• 2nd a section through the section plane AA out 1 ;
• 3rd a section through the section plane BB out 1 ;
• 4th a plan view of a layer of the applied and solidified powdery material in an area without a component;

1 shows an example of an embodiment of a layer in the additive manufacturing of two components 3rd , 3 ' using the method according to the invention. The construction area in which the powdery material is applied and selectively solidified is by a square picture box on the edge 1 limited. The footprint that is the bottom of the picture box 1 forms and on which the first layer of the powdery material is applied, is by an in 1 Carrier plate, not shown 2nd educated. The area between the outer contours of the components 3rd , 3 ' and the picture box 1 is of a support structure 4th pulled through. The support structure 4th consists of honeycomb support structure units 5 . Between the outer contour of the components 3rd , 3 ' and the support structure 4th is a space 7 trained of no support structure 4th having. By that in the space 7 arranged, non-bound powdery material there is no fixed connection between the components 3rd , 3 ' and the support structure 4th . At the corners of the square picture box 1 are test specimens 8th to check the accuracy of the additive process or the resulting components 3rd , 3 ' manufactured in the additive manufacturing process.

In 2nd is a section through the section plane AA out 1 in an area of additively manufactured components 3rd , 3 ' and in 3rd a section through the section plane BB out 1 in an area without a component 3rd , 3 ' shown. The support structure 4th extends through all layers. In addition, the support structure 4th plates 6 on, parallel to the backing plate 2nd are arranged at certain intervals and the support structure units 5 , the chambers between the plates 6 form, limit horizontally. In 2nd it can be seen in particular that the width of the spaces 7 between a component 3rd , 3 ' and the support structure 4th depending on the geometric shape of the component 3rd , 3 ' can vary. In particular, the width of the spaces 7 also vary in layers.

4th showed a top view of a layer consisting solely of the support structure 4th with the honeycomb-shaped chambers of the support structure units 5 consists. On the long sides L of the picture box 1 are the support structure units 5 only selectively over the honeycomb corners and on the transverse sides Q over the honeycomb edges with the picture box 1 connected. However, other configurations are also possible, in particular in such a way that between the picture box 1 and the support structure 4th Another space and therefore no fixed connection between the picture box 1 and support structure 4th consists.

For additive manufacturing of a component, the first step is based on the design data of the component 3rd , 3 ' as well as the picture box used 1 a geometrically adapted support structure 4th calculated by the entire gap 7 between the outer contour of the components and the picture box 1 extends. In particular, openings can also be made in the component 3rd , 3 ' with the support structure 4th be provided. The calculation of the design of the support structure 4th can, in particular, be computer-controlled by a support frame generator. For the additive manufacturing of a component, the powdery material is layered within the image box which serves to delimit the construction area 1 applied evenly. Based on the design data of the respective layer, the powdery material is selectively solidified, for example by applying and gluing with a suitable binder. Then the carrier plate 2nd lowered by one layer thickness and the next layer of the powdery material applied. After all of the component has been applied 3rd , 3 ' the component is required layers 3rd , 3 ' from the picture box 1 removed and not with the component 3rd , 3 ' connected support structure 4th away. Elaborate post-processing steps to separate the support structure 4th and component 3rd , 3 ' are due to the gaps 7 between the component 3rd , 3 ' and the support structure 4th not mandatory. After removing the support structure 4th and the component 3rd , 3 ' from the picture box 1 can the next component 3rd , 3 ' be made within the image box. Alternatively, a continuous additive manufacturing process is also conceivable, after the application of the last layer for a component to be manufactured 3rd , 3 ' one parallel to the carrier plate 2nd arranged intermediate plate, which serves as the floor for the next component 3rd , 3 ' serves by solidifying the powdered material over the entire surface within the image box 1 can be trained. Instead of solidifying the powdery material over the entire surface, it is also conceivable to insert an already prefabricated intermediate plate from the outside.

Reference list

1

Picture box

2nd

Carrier plate

3, 3 '

Component

4th

Support structure

5

Support structure unit

6

plate

7

Space

8th

Test specimen

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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 19954891 A1 [0003]

Claims (19)

Method for the additive manufacturing of a component (3, 3 ') with a predetermined outer contour within an image box (1) serving as the boundary of a construction field, comprising the steps: a) applying a layer of a powdery material, b) selectively solidifying the powdery material based on construction data the layer, c) repeating steps a) and b) until the application and selective solidification of all layers required for additive manufacturing of the component (3, 3 '), characterized in that within each layer a support structure (4) in addition to the component (3, 3 ') is produced, the support structure (4) running through the area between the image box (1) and the outer contours of the component (3, 3') without contact with the component (3, 3 ') to be produced. Procedure according to Claim 1 , characterized in that the support structure (4) essentially runs through the entire area of the image box (1) not intended for the component (3, 3 ') without contact with the component (3, 3') to be produced. Method according to one of the preceding claims, characterized in that the support structure (4) is produced generatively, in particular by the selective solidification of the powdery material. Procedure according to Claim 3 , characterized in that the support structure (4) and the component (3, 3 ') are made of the same or different materials. Method according to one of the preceding claims, characterized in that the support structure (4) has at least partially closed support structure units (5). Method according to one of the preceding claims, characterized in that the support structure (4) is a hollow chamber structure. Procedure according to Claim 6 , characterized in that the support structure (4) has a honeycomb pattern. Method according to one of the preceding claims, characterized in that the support structure (4) has a plurality of plates (6) arranged in parallel and at a distance from one another with chambers between adjacent plates (6). Method according to one of the preceding claims, characterized in that the selective solidification is carried out by applying a binder provided for solidifying the powdery material or by laser melting, laser sintering or electron beam melting. Method according to one of the preceding claims, characterized in that the powdery material is sand or a metal powder or a polymer granulate or a ceramic powder. Device for the additive manufacturing of a generatively manufactured component (3, 3 ') with a predetermined outer contour within an image box (1) serving as a limitation of the construction field, comprising a support structure (4), characterized in that the support structure (4) is additive to the component is produced and extends over the entire area between the image box (1) and the outer contour of the component (3, 3 ') without contact with the component (3, 3') to be produced. Establishment after Claim 11 characterized in that the support structure (4) extends over the entire area of the image box (1) not provided for the component (3, 3 ') without contact with the component (3, 3') to be produced. Device according to one of claims 11 or 12, characterized in that the support structure (4) and the component (3, 3 ') are made of the same or different materials, in particular by selective solidification of a powdery material. Device according to one of claims 11 to 13, characterized in that the support structure (4) has at least partially closed support structure units (5). Device according to one of claims 11 to 14, characterized in that the support structure (4) is a hollow chamber structure. Establishment after Claim 15 , characterized in that the support structure (4) has a honeycomb pattern. Device according to one of claims 11 to 16, characterized in that the support structure (4) has a plurality of plates (6) arranged in parallel and at a distance from one another with chambers between adjacent plates (6). Device according to one of claims 11 to 17, characterized in that the component (3, 3 ') and the support structure (4) are formed by a selective solidification of a powdery material, the powdery material by applying a binder or by laser melting, laser sintering or electron beam melting is solidified. Device according to one of claims 11 to 18, characterized in that the powdery material is sand or a metal powder or a polymer granulate or a ceramic powder.

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