DE102022212786A1 - Method and system for the generative production of components in generative manufacturing processes and motor vehicle, comprising at least one component produced by means of the method - Google Patents

Abstract

The invention relates to a method for the generative production (12) of components (1) in generative manufacturing processes (3), wherein in a generative manufacturing process (3) a material (20) for producing one or more components (1) is provided with at least one additive (2) and the material (20) with the additive (2) is partially used for the generative production (12) of at least one component (1), and wherein after the generative production (12) at least one physical quantity of the additive (2) is detected, wherein from a change in the physical quantity of the additive (2) compared to a value of the physical quantity before the generative production (12) at least one piece of information regarding a change in a material property of the additive (2) and/or material (20) remaining after the generative manufacturing process (3) has been carried out is obtained, and the information is used in a further generative manufacturing process (3) to adapt the process parameters.The invention further relates to a system (5) for generative production (12) of components (1) in generative manufacturing processes (3) and a motor vehicle comprising at least one component (1) produced by means of the described method.

Description

The invention relates to a method and a system for the generative production of components in generative manufacturing processes and to a motor vehicle comprising at least one component produced by means of the method.

In generative manufacturing, for example using selective laser sintering, powder in a powder bed is partially melted by a laser so that the melted powder combines to form a component. The component is then removed from the powder bed and the powder that has not been converted into the component remains. To make optimal use of the powder, the remaining powder should also be used in further generative manufacturing processes. However, the remaining powder has at least partially experienced thermal stress from the previous generative manufacturing process. As a result, the material properties of the remaining powder no longer correspond to those of the starting material before the component was manufactured. If the powder is therefore used in another generative manufacturing process, the process parameters used up to now are no longer optimally adjusted to the existing powder quality. This results in poor component quality and a high reject rate.

Typically, the thermally pre-stressed powder is reused and refreshed with fresh powder that has not been thermally pre-stressed, whereby the resulting material properties are assumed to be approximately the same as those of fresh powder. However, the process parameters are still not optimally set due to a lack of knowledge of the actual material properties. Alternatively, the process parameters are often only adjusted after predefined interval steps. However, the constant refreshing of the powder means that after a few production processes the powder consists of an unknown composition of different ages. This means that the component properties may deteriorate with each new printing process despite the constant refreshing, which can ultimately result in component rejection. The powder is therefore usually disposed of after a defined number of cycles, whereby high-quality powder may also be lost.

The state of the art is still based on the US20200333295A1 It is known to use so-called tracers in powder-based additive manufacturing, whereby optimal conditions for additive manufacturing are determined depending on the mere presence of the tracer. However, determining the optimal conditions for additive manufacturing based on the mere presence of the tracer only allows binary coding per tracer, whereby if the tracer is present, this corresponds to a first condition for additive manufacturing and whereby if the tracer is not present, this corresponds to a second condition for additive manufacturing, which is correspondingly complicated and impractical. In addition, this method does not allow any conclusions to be drawn about the material properties of the material used in production, so it is not suitable for process-accompanying analysis of the material properties.

In addition, the US20220134435A1 proposes to optimize powder-based additive manufacturing processes by taking layer-by-layer images of the powder and using artificial intelligence to examine them for anomalies in real time. However, this method is at best capable of identifying optically detectable anomalies. In the process, anomalies in the powder bed that are not optically detectable may be overlooked, which subsequently result in components with deteriorated quality. In addition, the problem of adjusting the process parameters during the process remains unsolved by the method proposed here.

It is therefore the object of the present invention to provide a method and a system for the generative production of components in generative manufacturing processes, which enable a more cost-effective and process-reliable generative production of components compared to the prior art. Furthermore, it is the object of the invention to provide a motor vehicle which comprises at least one component produced according to such a method.

The object is achieved according to the invention by a method for the generative production of components in generative manufacturing processes with the features of claim 1, by a system for the generative production of components in generative manufacturing processes with the features of claim 9 and by a motor vehicle with the features of claim 10.

Advantageous embodiments of the method are specified in subclaims 2 to 8.

A first aspect of the invention relates to a method for the generative production of components in generative manufacturing processes, wherein in a generative manufacturing process a material for producing one or more components is provided with at least one additive and the material with the additive is partially used for the generative production of at least one component, and wherein after the generative production at least one physical quantity of the additive is detected, wherein from a change in the physical quantity of the additive compared to a value of the physical quantity before the generative production at least one piece of information regarding a change in a material property of the additive and/or material remaining after execution of the generative manufacturing process is obtained, and the information is used in a further generative manufacturing process to adapt the process parameters.

The material can be the material from which the component manufactured in the generative manufacturing process essentially consists.

The material can, for example, be in the form of a powder which is used to manufacture components in such a way that the powder is partially melted and thus combined to form at least one component.

The value of the physical quantity before generative manufacturing can, for example, be known as a known material property in the case of fresh material used for the first time to manufacture components, so that the value can be taken from a table with known material properties, for example.

After the generative production of the component, it can be removed from a reservoir containing the material with the additive, for example a powder bed, whereby after the removal of the component, material not used to produce the component and unused additive remain in the reservoir.

The generative production of the component can be carried out, for example, using at least one of the following known generative manufacturing processes: laser sintering, selective laser sintering, multi jet fusion, binder jetting, digital light processing, stereolithography or injection molding. Furthermore, it can be powder-based, filament-based or resin-based generative manufacturing processes.

The process parameters are the parameters that are used in the respective generative manufacturing process to partially convert the material into the component. These can be physical parameters, for example thermal energy and/or radiation energy or laser energy acting on the material or additive; travel speed of radiation sources or laser sources that are used for generative manufacturing; temperatures of the environment of the material or additive during generative manufacturing or temperatures of the powder bed surface, powder dispensing unit and reservoir. A predefined or preprogrammed relative movement between the radiation source and the material with the additive or the exposure path during the manufacturing process as well as the smallest distance between adjacent sections of the exposure path can also be part of the process parameters, as can a layer thickness of the material before or during generative manufacturing.

The material property can be, for example, melt viscosity, melting point, flowability, particle size distribution, bulk density and/or tap density.

The information obtained from the change in the physical quantity regarding a change in a material property can be obtained, for example, by assigning the value of the physical quantity to a value of a material property. In other words, the material property can be functionally dependent on the physical quantity, so that each value of the physical quantity is assigned to a defined material property. The functional dependency can be predefined, for example, by designing a coding in which each value of the physical quantity is assigned to a corresponding material property. Alternatively, it is conceivable that the value of the physical quantity of the additive is physically correlated with the value of the material property, for example through a functional dependency of the two according to a natural law. The functional dependency does not have to be continuous. A known relationship between a group of values of the physical quantity and the values of the material property is also sufficient, whereby interpolation can then be carried out in the actually unknown range between the known values.

The information can be obtained automatically, for example by a processor unit receiving the detected value of the physical quantity during the process, i.e., for example, after each generative production of a component, and using this to infer the material property.

The information obtained from the change in the physical quantity can be used in a further generative manufacturing process to adjust the process parameters insofar as the process parameters are changed in at least one further generative manufacturing process This can be done at least partially automatically, for example by using suitable software.

For example, if a reduction in melt viscosity was determined after a first generative manufacturing process, the radiation output in a second generative manufacturing process following the first generative manufacturing process can be reduced compared to that from the first generative manufacturing process. It is also intended that the process parameters are adjusted when the detected value of the physical quantity falls below a predefined limit value. This can be done automatically by a processor unit comparing the detected values of the physical quantity with the predefined limit value during the process, i.e. for example after each generative manufacturing process, and if the limit is exceeded or not reached, causing a predefined adjustment of the process parameters. The process parameters can be changed in such a way that their adjustment in a further generative manufacturing process results in the value of the physical quantity moving away from the limit value. For example, if the physical value of the additive is found to be below the limit, which means that the melt viscosity is disadvantageous for additive manufacturing, this can be taken into account in a further additive manufacturing process by reducing the radiation output. Such adjustments to the process parameters based on known material properties are known per se and can be taken from the relevant tables, for example.

In one embodiment, a physical quantity of the additive is detected before and after the additive manufacturing process, and at least one piece of information is obtained from a change in the value of the physical quantity detected in each case. This is advantageous in that the information regarding the change in the material properties of the material and/or the additive associated with the additive manufacturing process is obtained with increased certainty through the respective detection, since no specific, possibly uncertain value of the physical quantity is assumed to be given before the additive manufacturing process. Detection before the additive manufacturing process is particularly useful when the material properties of the material and the additive are uncertain or unknown, for example because of their use in previous additive manufacturing processes. The information can then be used advantageously to adapt the process parameters to the respective material properties during the process. This ultimately results in an advantageously reduced scrap rate of components.

According to one embodiment, at least one of the physical quantities is the concentration of the additive. The concentration can advantageously be determined precisely and with little effort, for example by mass spectrometry, or also by means of optical methods in which the ratio of additive to material can be determined by optical properties of the additive, such as a change in absorption compared to the material.

Furthermore, the physical quantity can be optical or optically detectable quantities, more specifically, for example, absorption, reflection and/or transmission of electromagnetic radiation. Physical quantities from electronics are also conceivable, such as electrical polarization, electrical conductivity, electrical resistance and/or physical quantities from magnetism, such as magnetization or inductance.

In the context of the present disclosure, the pH value should also be understood as a physical quantity.

In one embodiment, the additive comprises at least one of the following: modified polymers, fluorescent particles, color particles, magnetic particles, metallic particles, silicate-encapsulated DNA or additives which are designed to change the pH value of the material. Several different additives can be combined. The exemplary additives listed here are advantageous in that they can be detected with high accuracy using detection methods known per se. The additive can be present in the material in a concentration of 1 ppm - 1000 ppm. More specifically, concentrations of 1 ppm - 10 ppm, 10 ppm - 100 ppm or 100 ppm - 1000 ppm are conceivable. The ratio of additive to material therefore remains so low that the additives converted into components can have practically no negative effects on the quality of the components. In addition, the additives can have similar material properties to the material, so that the process parameters involved have similar effects on the additive as on the material. Thus, the additives do not have a detrimental effect on the quality of the generatively manufactured components, but on the contrary ensure a reduced rejection of components due to unfavorable or not adjusted process parameters.

The detection of the physical size of the additive depends on the additive selected. In conjunction with the above-mentioned example additives, optical or chemical detection, or even mass spectrometry, can therefore be considered.

According to one embodiment, a sample of the material with the additive is taken and the physical size of the additive is detected using the sample. This is advantageous, for example, if the detection of the physical size of the additive in-situ, i.e. without sampling and external detection, is not possible. This is the case, for example, if the concentration can only be determined using mass spectrometry. This embodiment is also advantageous if the detection of the physical size in-situ is associated with adverse changes in the material properties, for example if chemicals have to be added for detection.

In an alternative embodiment, the physical size of the additive is detected without at least partial removal of material and at least one type of additive. This has the advantage that removal for external detection is not necessary and thus the physical size of the additive can be detected in-situ and during the generative manufacturing processes. For example, the optical detection methods listed above can be used for this purpose. Since no removal and external detection takes place in this embodiment, the generative manufacturing process is accelerated accordingly, with the process parameters being continuously adapted to the respective material properties through the process-accompanying detection.

In a further embodiment, several generative manufacturing processes are carried out, whereby material and/or further additives are mixed in between two consecutive generative manufacturing processes and a homogeneous mixture is produced. The mixed material and/or the further additive can be fresh material or additive, i.e. material or additive that has not yet been used in a generative manufacturing process. By adding material and/or additives, the material properties of the material and/or additive used in the manufacturing processes can be advantageously adapted. For example, as soon as a change in the physical quantity has been detected which implies a critical change in the material property, a poor flowability of the material and/or additive, a predefined amount of fresh material and/or additive can be added in a targeted manner in order to move the material property, for example the flowability, back to a non-critical range. The predefined quantity can be specifically selected with regard to a mass of material and/or additive or various additives to be added in order to obtain the desired material properties of the material and/or additive, since the composition of material and additive prior to addition or their material properties are known through the detection of the physical size of the additive. Furthermore, the homogeneous mixture of material and additive proposed in this embodiment advantageously ensures that the additive is spatially evenly distributed in the material. This allows a statistically representative detection of the physical size both in the case of a sample taken for this purpose and in the case of in-situ detection, so that the information regarding changing material properties of the material and/or additive is also statistically meaningful.

According to one embodiment of the invention, the additive and the material each comprise particles whose maximum dimensions differ from one another by less than 25%. This advantageously ensures that the material properties such as flowability, bulk density and tap density of the material and additive are similar, which enables homogeneous mixtures of material and additive with the above-mentioned advantages.

For example, the material has particles with maximum dimensions of 50 µm to 120 µm.

• - aus einer Änderung der physikalischen Größe des Zusatzstoffs gegenüber einem Wert der physikalischen Größe des Zusatzstoffs zumindest eine Information hinsichtlich einer Veränderung einer Materialeigenschaft des Zusatzstoffs und/oder Materials zu gewinnen und
• - die Information in einem weiteren generativen Fertigungsprozess zur Anpassung der Prozessparameter zu verwenden und entsprechend die Prozessparameter einzustellen.

A second aspect of the invention relates to a system for the generative production of components in generative manufacturing processes. The system has a detection unit which is designed to detect a value of a physical quantity of an additive in a material for the generative production of at least one component. The system also comprises a processor unit which is designed to:

• - to obtain at least one piece of information regarding a change in a material property of the additive and/or material from a change in the physical size of the additive compared to a value of the physical size of the additive and
• - to use the information in a further generative manufacturing process to adapt the process parameters and to set the process parameters accordingly.

The system according to the second aspect of the invention can be used to carry out the method be designed according to the first aspect of the invention.

The processor unit can receive data from the detection unit, whereby the value of the physical quantity detected by the detection unit is passed on to the processor unit. Furthermore, the processor unit can access data relating to the material properties of the additive and/or material from a database with material properties known per se in order to obtain corresponding values of the physical quantity in the case of fresh additive and/or material.

The system can further comprise an output unit for outputting additive and/or material. The processor unit can further be designed to calculate an amount of additive and/or material to be added by the output unit based on existing material properties in order to achieve a target material property of the material and/or additive after addition. The target can be a specific value of the respective material property, for example a specific bulk density.

A third aspect of the invention relates to a motor vehicle comprising at least one component produced by means of the method according to the first aspect of the invention. The motor vehicle can be, for example, a passenger car or, more specifically, an at least partially electrically driven passenger car.

The invention is explained below with reference to the embodiment shown in the accompanying drawings.

• 1: eine schematische Übersicht eines Ausführungsbeispiels des Verfahrens sowie des Systems zur generativen Herstellung von Bauteilen in generativen Fertigungsprozessen; sowie
• 2: schematisch einen Mischprozess, welcher eine homogene Mischung aus Material und Zusatzstoff erzeugt.

Show it

• 1 : a schematic overview of an embodiment of the method and the system for the generative production of components in generative manufacturing processes; and
• 2 : schematically shows a mixing process which produces a homogeneous mixture of material and additive.

In 1 an embodiment of the proposed method and the system 5 for the generative production 12 of components 1 in generative manufacturing processes 3 is shown schematically.

An output unit 8, a detection unit 6, a mixing unit 9 and a processor unit 7 are shown as components of the system 5. In this exemplary embodiment, the output unit 8 is designed to output additive 2 and material 20 in the form of a powder 21 for the generative production of components 1. The detection unit 6 is designed to detect at least one physical quantity of the additive 2. The processor unit 7 is designed to obtain information regarding a change in the material properties of the powder 21 and/or the additive 2 based on the physical quantity of the additive 2 detected by the detection unit 6 and to use the information to adapt the process parameters in a further production process 3. In addition, in this exemplary embodiment, the processor unit 7 is designed to specify the quantities of material 20 or powder 21 and/or additive 2 output via the output unit 8 based on the information.

With regard to the method for the generative production 12 of components 1 in generative manufacturing processes 3, 1 a cycle in which several generative manufacturing processes 3 are carried out one after the other. In each generative manufacturing process 3, at least one component 1 is generatively manufactured. Starting from the mixing unit 9, the following will initially assume a composition of powder 21 and additive 2 present there, whereby the material properties of the powder 21 and those of the additive 2 are assumed to be unknown here. This can be the case, for example, if the powder 21 present in the mixing unit 9 consists of the additive 2 to form a first component of powder 21 and additive 2, which were already used in a previous generative manufacturing process 3 but not converted into a component 1. However, this first component was at least partially exposed to process parameters such as thermal energy or radiation energy in the previous generative manufacturing process 3, so that the material properties of powder 21 and/or additive 2 no longer correspond to the known material properties of fresh powder 21 and/or additive 2. The material properties of this first component are then unknown or subject to uncertainty at this point. As a second component, a quantity of further powder 21 and further additives 2 can be added in the mixing unit 9 via the output unit 8. This can also be powder 21 and/or additives 2 that have already been used in previous generative manufacturing processes 3, so that the second component can also have unknown material properties. Even if fresh powder 21 and fresh additives 2 are added here, the first component of powder 21 and additive 2 and thus the material properties of the powder present at this point remain the same. Total of powder 21 and additive 2 unknown.

This combination of powder 21 and additive 2 is used in the 1 The powder is mixed in the mixing unit 9 shown to form a homogeneous mixture 4, which is then provided for the generative production 12 of components 1. For example, this can involve the powder provision 11 of powder 21 in a powder bed.

Subsequently, at least one physical quantity of the additive 2 present homogeneously in the powder 21 is detected by means of the detection unit 6. For example, this can be done by taking a sample of the powder 21 with the additive 2 from the powder bed and examining it externally with regard to the physical quantity of the additive 2. One conceivable option here is mass spectrometric detection of the concentration of the additive 2 in the powder 21 from the sample. Alternatively, the physical quantity can also be detected in the powder bed and without removing powder 21 and additive 2, for example by optical detection of the physical quantity. Based on the detected value of the physical quantity of the additive 2, information regarding a change in the material properties of powder 21 and/or additive 2 as a result of previously carried out generative manufacturing processes 3 can be obtained by means of the processor unit 7.

The processor unit 7 uses this information by adapting the process parameters to the changed or corresponding material properties of powder 21 and/or additive 2 at this point based on the information. This can be done, for example, by increasing or reducing the radiation power of a radiation source used in the subsequent generative production 12 of the at least one component 1 and acting on the material 20 or powder 21 with the additive 2 compared to the radiation power used in a previous generative manufacturing process 3. Consequently, the process parameters can be adapted to the material properties present immediately before the generative production 12, whereby the rejection of components 1 due to process parameters not optimally adapted to the material properties is significantly reduced.

The at least one component 1 produced during the generative production 12 can now be removed from the powder bed, whereby the powder 21 not converted into the at least one component 1 and the additive 2 not converted into the at least one component 1 remain in the powder bed. This recyclate 10 is also intended to be used in subsequent generative manufacturing processes 3 for optimized utilization of powder 20 and additive 2.

For this purpose, as in 1 It can also be seen that the physical size of the additive 2 in the recyclate 10 is detected at this point by means of the detection unit 6. From the change in the value of the physical size of the additive 2 detected here after the generative production 12 compared to its value before the generative production 12, information can be obtained regarding the change in the material properties of powder 21 and additive 2. This information is then used in a further generative production process 3 to adjust the process parameters. In addition, the information can, as in 1 shown, can be used to adjust the mixing ratios of powder 21 and additive 2 by adding further powder 21 and/or further additive 2. To do this, the processor unit 7 can, for example, based on the now known material properties of the recyclate 10, cause the output unit 8 to add an amount of material 20 or powder 21 and/or additive 2 calculated by the processor unit 7 in order to achieve a predefined or preprogrammed target for the material properties after the addition. For example, based on a first value of the physical quantity of the additive 2 detected in the recyclate 10, which corresponds to a first bulk density of the additive 2 and/or powder 21, the processor unit 7 can calculate how much fresh powder 21 and additive 2 must be added in order to achieve a target for the bulk density. The masses of the recyclate 10 and the fresh powder 21 or additive 2 required for this calculation are essentially given by the powder 21 due to the low concentrations of the additive in the range of, for example, 1 ppm - 1000 ppm and can be weighed.

The 1 The cycle process shown is closed by mixing the recyclate 10 in the mixing unit 9 with the additional powder 21 and/or additive 2 to form a homogeneous mixture 4. A further generative manufacturing process 3 can then be carried out in accordance with the above description.

In 2 A mixing process is shown schematically. In this process, a homogeneous mixture 4 is produced from a material 20 or a powder 21 on the one hand and an additive 2 on the other hand, which mixture is produced from the material 20 or the powder 1 and the additive 2. This homogeneous mixture 4 can then be used for a generative manufacturing process 3 for the generative production 12 of Components 1 as shown in 1 shown and described previously.

In the homogeneous mixture 4, the additive 2 is spatially homogeneous, i.e. evenly distributed, so that the physical size of the additive 2 can also be detected by taking a sample of material 20 or powder 21 with additive 2, whereby the sample is statistically representative of the entirety of the present material 20 or powder 21 with the additive 2. As an alternative to the sample, a subset of the material 20 or powder 21 with the additive 2 can also be examined with regard to the physical size of the additive 2 without the subset being taken from the entirety. Due to the homogeneity of the homogeneous mixture 4, the physical size determined in this way is also representative of the entirety of material 20 or powder 21 and additive 2.

List of reference symbols

1

Component

2

Additive

3

Manufacturing process

4

Homogeneous mixture

5

system

6

Detection unit

7

Processor unit

8th

Output unit

9

Mixing unit

10

Recycled

11

Powder supply

12

Generative manufacturing

20

material

21

powder

QUOTES INCLUDED IN THE DESCRIPTION

This list of 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 accepts no liability for any errors or omissions.

Cited patent literature

• US 20200333295 A1 [0004]
• US 20220134435 A1 [0005]

Claims (10)

Method for the generative production (12) of components (1) in generative manufacturing processes (3), wherein in a generative manufacturing process (3) a material (20) for producing one or more components (1) is provided with at least one additive (2) and the material (20) with the additive (2) is partially used for the generative production (12) of at least one component (1), and wherein after the generative production (12) at least one physical quantity of the additive (2) is detected, wherein from a change in the physical quantity of the additive (2) compared to a value of the physical quantity before the generative production (12) at least one piece of information regarding a change in a material property of the additive (2) and/or material (20) remaining after execution of the generative manufacturing process (3) is obtained, and the information is used in a further generative manufacturing process (3) to adapt the process parameters. Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to Claim 1 , wherein a sample of the material (20) with the additive (2) is taken and the physical size of the additive (2) is detected based on the sample. Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to Claim 1 , wherein the physical size of the additive (2) is detected without at least partial removal of material (20) and the at least one type of additive (2). Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to one of the preceding claims, wherein a physical quantity of the additive (2) is detected before and after the generative production (12), and wherein the at least one item of information is obtained from a change in the respectively detected value of the physical quantity. Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to one of the preceding claims, wherein at least one of the physical variables is the concentration of the additive (2). Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to one of the preceding claims, wherein the additive (2) comprises at least one of the following: modified polymers, fluorescent particles, color particles, magnetic particles, metallic particles, silicate-encapsulated DNA or additives which are designed to change the pH value of the material. Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to one of the preceding claims, wherein several generative manufacturing processes (3) are carried out, and wherein between two successive generative manufacturing processes (3) material (20) and/or further additive (2) is added and a homogeneous mixture (4) is produced. Method for the generative production (12) of components (1) in generative manufacturing processes (3) according to one of the preceding claims, wherein the additive (2) and the material (20) each comprise particles whose maximum extensions differ from one another by less than 25%. System (5) for the generative production (12) of components (1) in generative manufacturing processes (3), comprising a detection unit (6) which is designed to detect a value of a physical quantity of an additive (2) in a material (20) for the generative production (12) of at least one component (1), wherein the system (5) further comprises a processor unit (7) which is designed to: • obtain at least one piece of information regarding a change in a material property of the additive (2) and/or material (20) from a change in the physical quantity of the additive (2) compared to a value of the physical quantity of the additive (2) and • use the information in a further generative manufacturing process (3) to adapt the process parameters and to set the process parameters accordingly. Motor vehicle, comprising at least one by means of the method according to one of the Claims 1 until 8th manufactured component (1).

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