EP4244752A2

EP4244752A2 - Method for providing a digital printed model, and method for additively manufacturing a component

Info

Publication number: EP4244752A2
Application number: EP21810334.9A
Authority: EP
Inventors: Shahrooz Sadeghi Borujeni; Sven Crull
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2020-11-12
Filing date: 2021-11-10
Publication date: 2023-09-20
Also published as: WO2022101237A2; DE102020214268A1; WO2022101237A3

Abstract

The invention relates to a method (A) for providing a digital printed model (1) and an additive manufacturing method (B) for a component (2), wherein a CAD model (3) of the component (2) is provided; a thermal treatment is simulated, as a result of which a digital deformation model (4) of the component (2) is produced; the CAD model (3) is compared with the deformation model (3), as a result of which local deviation amounts (6) between the models (3, 4) are determined; the models (3, 4) are aligned with each other in such a way that a total deviation amount formed from the deviation amounts (6) becomes minimal; and the printed model (1) is produced by modifying the CAD model (3) on the basis of the deviation amounts (6). According to the invention, the models (3, 4) are aligned with each other according to a condition (100, 101, 102, 103) according to which special geometric elements (9, 10) of the component (2) that correspond to one another are arranged in such a way that the total deviation amount formed from the deviation amounts (6) becomes minimal while satisfying this condition (100, 101, 102, 103).

Description

description

Method for providing a digital print model and method for additively manufacturing a component

According to patent claim 1, the invention relates to a method by means of which a digital printing model is provided, by means of which a component can be produced additively. Furthermore, the invention according to patent claim 9 relates to a method for the additive manufacturing of a component.

Nowadays, additive manufacturing methods are used in particular to produce components whose geometric shape cannot be realized or can only be realized with the use of particularly great effort using conventional, for example metal-cutting, manufacturing methods. Furthermore, the additive manufacturing processes are becoming more and more profitable with increasing further development, which is why more and more additive manufacturing processes are currently finding their way into the series production of components.

The additive manufacturing method can be embodied, for example, as 3D printing, in particular as a binder jetting printing method. Accordingly, a production unit is designed as a 3D printer, for example. The manufacturing unit, by means of which the binder jetting method is used to produce components, is configured to apply directly alternating layers of a binder and a material powder to a printing bed of the 3D printer in a printing process. In this case, it can be provided, for example, that a first layer, which is applied to the printing bed by means of the 3D printer, is a binder layer in order to prevent the object to be printed from slipping on the printing bed in an undesirable manner. The material powder is, for example, a metallic powder, the material powder and the binder, which can be a liquid, being designed or selected in such a way that two adjacent material powder layers are connected to one another by means of a binder layer. This means that in binder jet 3D printing, a first layer of material powder is applied to the print bed. A binder layer is then applied to this first layer of material powder at certain points (determined by a construction plan, such as a model of the component to be printed). This is followed by applying another material powder layer to the binder layer. The two material powder layers are connected to one another by means of the binder layer, glued for example. On the other hand, the first material powder layer consisting of individual powder elements is solidified by the individual powder elements being connected to one another by the application of the binder layer, since the binder penetrates into the material powder layer between the powder elements and connects the powder elements to one another.

As a result of such printing or production, an intermediate product - a so-called green part - "grows" with an increasing number of layers along a vertical printing axis, for example, with a digital print model including a geometry of the intermediate product or green part and in particular the points on which the binder is applied, characterized. In other words, the production unit is provided with the digital print model, with the production unit being designed to use the digital print model to arrange the alternating layers of binding agent or material powder on the print bed.

In order to improve the mechanical properties (such as strength, etc.) of the intermediate product or green part and to produce the corresponding component, the intermediate product or green part is heat-treated, for example sintered in a sintering furnace. The component is therefore produced in that the green part is heat-treated, in particular sintered. During the heat treatment or sintering, deformations occur on the component resulting from the green part, in particular due to gravitation, friction of the powder elements and anisotropic material properties of the material powder and/or the binder, etc. Furthermore, during heat treatment or sintering, the binder loses volume and/or partially escapes from the green part/component or is expelled. In addition, porosity reductions occur. Because of this, the green part shrinks and/or warps non-linearly during the heat treatment, so that a final geometry of the sintered component, which was produced by sintering the green part, is deformed in relation to a target geometry of the component due to the non-linear deformations. Due to the non-linearity of the deformations, hot spots or "focal points" occur on/in the component, at which the deformations are particularly pronounced and/or the deformations cannot be compensated for.

Accordingly, for the additive manufacturing of the component, there is a need to take into account and at least partially compensate for the deformations that occur as a result of the heat treatment during the printing process. For this purpose, for example, a simulation of the heat treatment is known, whereby an expected shrinkage and / or Warping behavior of the green part can be determined. On the basis of corresponding simulation results, a geometry of the digital print model is to be changed or modified in such a way that the deformations caused during the heat treatment of the green part result in the component having the final geometry that corresponds as closely as possible to the target geometry.

However, such a simulation of the heat treatment is particularly complex, since the non-linear deformations are particularly difficult to efficiently compensate. This is because the non-linear deformations occur on/in the component in some areas of the component, as a result of which deviations between the final geometry and the target geometry are particularly difficult to calculate or to compensate for.

US 2017 372 480 A1 discloses a system for compensating for thermal deformation during the manufacture of an object. In this case, a computing unit is designed to receive a model of the object. The computing unit is also designed to extract nodes that have a position and characterize a surface of the object. The processing unit is further configured to simulate the production of the object and to determine changes in the position of the nodes. Furthermore, the computing unit is set up to compensate for the thermal deformation by applying a trained neural network by modifying the object in accordance with the position changes, said trained neural network having been trained with previous manufacturing simulations. The computing unit is also designed to output a modified model of the object.

In particular due to the use of the neural network and the need for training thereof, this conventional system is particularly complex and not very efficient in order to compensate for the thermal deformation.

The object of the present invention is to reduce the effort involved in additively manufacturing a component with particularly advantageous dimensional tolerances.

This object is achieved by a method designed according to patent claim 1 for providing a digital printing model, based on which a component can be produced additively. Furthermore, this object is achieved by a method designed according to patent claim 9 for additively manufacturing the component. Features, Benefits and Beneficial Configurations of the method according to the invention for providing the digital print model are to be regarded as features, advantages and advantageous configurations of the method for additively manufacturing the component and vice versa.

According to a first aspect of the invention, a method for providing a digital print model is proposed, wherein the print model provided or that can be provided by means of the method can be used or is used for the additive manufacturing of the component. The component is, for example, a metallic component that can be produced or is produced by means of an additive manufacturing method. The component is in particular a component that is used in the field of machine and/or plant construction, for example as a vehicle component, as a component of a production unit for vehicles, etc. The component can be used, for example, in motor vehicle construction, in particular series motor vehicle construction, or be used, for example as a tool, component, semi-finished product, etc. or as a component thereof.

In a (for example first) step S1 of the method, a CAD model (CAD: computer-aided design) of the component is provided. In this case, the CAD model has a target geometry of the component, ie information or data that characterizes a shape and dimensions or relative dimensional ratios of the component. The target geometry corresponds to a final geometry which the finished component should have—as precisely as possible. Ideally, the component has the target geometry of the CAD model as the end geometry when the component has been completely manufactured. In other words, it is provided that the finished component and the CAD model correspond to one another. However, as explained at the outset, this is not readily possible, particularly if heat treatment is required to produce the component. This is the case, for example, when a green part is first produced when the component is produced by means of a binder jetting printing process, and the green part is then subjected to a heat treatment in order to finish producing the component.

In a further (for example second) step S2 of the method, a heat treatment is simulated using the CAD model, as a result of which a digital deformation model of the component to be manufactured is generated. The deformation model is thus generated or provided by, for example by means of a computer simulation, simulating the exposure of the CAD model to thermal energy occurring during the heat treatment. The deformation model has a deformation geometry or a deformed geometry of the component, in particular an intermediate product or the green part, where the deformation geometry and the target or end geometry differ from one another due to deformations. In this respect, the deformation geometry has information or data that characterizes a shape and dimensions or relative dimensional ratios of the component that the component would have if it had been manufactured using the unmodified CAD model. However, the deformation geometry is undesirable as the target or end geometry of the component.

The method has a further (for example third) step S3, in which the CAD model is compared with the deformation model, as a result of which local deviation amounts between the CAD model and the deformation model are determined. The respective local deviation amount is, for example, an amount of a linear measure that characterizes the local deviation as a straight distance between corresponding geometric elements (such as points, edges, surfaces, etc.) of the CAD model and the deformation model. Furthermore, the local amount of deviation can be an amount of an angular measure that characterizes the local deviation as an angle of deviation between the mutually corresponding geometric elements of the CAD model and the deformation model. In this case, the straight distance and/or the angle of deviation between the corresponding geometric elements is/are related in particular to one or more of the three spatial directions x, y, z. If the CAD model and the deformation model are each available as a networked component model - e.g. in order to examine a probable component behavior under load using an FEM analysis - the respective local deviation amount between a network node of the CAD model and a corresponding network node of the deformation model can be determined .

The method also includes a further (e.g. fourth) step S4, in which the CAD model and the deformation model are aligned with one another in such a way that a total deviation amount, which is formed from the local deviation amounts between the CAD model and the deformation model, becomes minimal. The process of aligning the CAD model and the deformation model with one another is carried out by moving/translating the two models relative to one another or one of the two models relative to the other of the models in a translatory and/or rotary manner. In this case, local deviation amounts are determined/calculated at predetermined/predeterminable points of the models, which are then added to the total deviation amount. The two models are said to be most aligned when the total variance amount, i.e. a sum of all local variance amounts, has become minimal. Accordingly, the two models in question are aligned in particular by means of a so-called best-fit algorithm (best-fit: best possible adjustment). The alignment is carried out without actually producing the models involved, for example in a simulative manner.

In a further (for example fifth) step S5 of the method, the print model of the component to be manufactured is generated by the CAD model being changed or modified using the local deviation amounts. The digital print model is therefore based on the CAD model, which was changed/modified using the local deviation amounts. If, for example, the deformation model has a smaller dimension between two points than the CAD model, the print model is created on the basis of the CAD model, with the dimension of the CAD model being extended by the amount of deviation at the corresponding points of the print model. If the deformation model between the two points has a larger size than the CAD model, the size of the CAD model is reduced by the amount of deviation at the corresponding points of the pressure model when/for creating the print model. The procedure for creating the print model is analogous in order to compensate for angular deviations: If, for example, a surface or edge of the deformation model is tilted by a deviation angle against a corresponding surface or edge of the CAD model, the corresponding surface/edge is tilted when/for creating the print model of the pressure model are tilted in opposite directions by the amount of deviation angle.

In order to reduce the effort involved in additively manufacturing the component with particularly advantageous dimensional tolerances, it is provided according to the invention that the CAD model and the deformation model are aligned with one another with at least one condition, according to which a predetermined special geometry element of the CAD model and a special geometry element corresponding thereto of the deformation model are arranged next to one another, in particular congruently. Step S4 of the method is therefore carried out on the premise that the special geometry elements which correspond to one another remain arranged on one another, in particular aligned with one another. Consequently, the total deviation amount formed from the local deviation amounts becomes minimal when this condition is met.

It is to be understood that the total amount of deviation formed while meeting the condition may be greater than the total amount of deviation that would be formed without the condition. However, the process in which the CAD model and the Deformation model are aligned with each other while complying with the condition, preferred according to the invention, since this process has a particularly advantageous ratio between effort and benefit.

The digital print model and consequently the finished component includes at least the specified special geometry element, which is of particular importance for the production and/or for the functionality of the component. In this case, the respective special geometry element is in particular predetermined or specified in that a designer of the component identifies the special geometry elements as such when creating the corresponding CAD model and marks them as such in the CAD model, for example. The respective special geometry element is, for example, a respective point, a respective (even or odd) edge, a respective corner and/or a respective (even or uneven) surface of the component or the CAD model.

Since at least one respective point or at least one respective section of the two models to be aligned with one another is already defined by the predefined condition, the effort required to provide the print model is reduced, in particular the effort required to align the CAD model with the deformation model or vice versa. In this way, the printing model is created or provided more efficiently in the method, as a result of which the additive manufacturing of the component can be carried out particularly easily and/or with little effort.

When the component is actually manufactured, there is a point on/in the component at which a particularly low degree of deviation occurs during sintering or heat treatment. In particular, this point is free from deviation. So this point has zero deformation, which is why this point is called the zero deformation point. The zero deformation point and a footprint over which the green part for heat treatment is placed coincide. In other words, with respect to a height of the green part, the zero deformation point is at the same height as the footprint. In addition, the zero deformation point is congruent with the center of gravity of the green part in relation to a width and a length of the green part. The same applies when the finished sintered or heat-treated component is considered: the zero deformation point lies in a contact plane of the component and is congruent with the component's center of gravity in relation to a width and a length of the component. Accordingly, the green part at the zero deformation point is not deformed or only deformed to a particularly small extent by the heat treatment. To put it simply, the green part deforms or shrinks “towards the zero deformation point” or “around the zero deformation point” as a result of sintering. Since the zero deformation point of the corresponding model is known or can be easily determined, according to a further advantageous embodiment of the method, the zero deformation point of the CAD model and a corresponding zero deformation point of the deformation model are determined in order to align the CAD model and the deformation model in order to -Align the model and the deformation model at the zero deformation points. This means that the respective geometry special element can be the respective zero deformation point. In other words, the CAD model has the special geometry element configured as the zero deformation point, with the deformation model having a special geometry element corresponding to the special geometry element, which is configured as the zero deformation point of the deformation model.

In the method, therefore, the zero deformation point of the CAD model and the zero deformation point of the deformation model are first ascertained or determined. Thereafter, the CAD model and the deformation model are aligned with one another, so that the zero deformation point of the CAD model and the zero deformation point of the deformation model coincide. Since a positional arrangement of the zero deformation point does not change by sintering, the zero deformation point can be regarded as a common point of the CAD model and the deformation model. Step S4 of the method is therefore carried out on the premise that the zero deformation points which correspond to one another remain arranged on one another, in particular aligned with one another.

That the zero deformation point of the CAD model and the zero deformation point of the deformation model must not fall apart or deviate from each other can be the or another condition that is met for aligning the CAD model and the deformation model with one another. Consequently, the condition according to which the predetermined special geometry element of the CAD model and the predetermined special geometry element of the deformation model are arranged next to one another, in particular congruently, is met if the zero deformation point of the CAD model and the zero deformation point of the deformation model are at or during the alignment of the CAD model and the deformation model coincide or remain arranged next to one another or congruently. Furthermore, the condition is met when the zero deformation points coincide due to the alignment of the CAD model and the deformation model. The condition that the zero deformation points do not fall apart or do not deviate from one another during alignment further reinforces the effect that the effort involved in providing the print model, in particular the effort involved in aligning the CAD model and the deformation model with one another, is reduced.

According to a further advantageous embodiment of the method, it is provided that, in order to align the CAD model and the deformation model with one another, a functional element of the CAD model that characterizes a functionality of the component and a functional element of the deformation model that corresponds thereto are determined in order to match the CAD model and the deformation model align the functional elements with each other.

Accordingly, the special geometry element can alternatively or additionally be the functional element of the component. In this case, the special geometry element is of particular importance for the functionality that is to be provided by the component. For example, the functional element of the component or the special geometry element is a surface, such as a surface used to form a material, positive and/or non-positive connection device, etc. The functional element can also be a hole, in particular a unthreaded and/or provided with an internal thread through or blind hole, around a groove etc. It is also conceivable that the functional element is designed as a material projection, which serves, for example, to form a material, form and/or force-fitting device, for example as an unthreaded and/or provided with an external thread pin or as another correspondingly designed material elevation.

The functional element of the CAD model and the functional element of the deformation model are thus first ascertained or determined. The CAD model and the deformation model are then aligned with one another, with the functional element of the CAD model and the functional element of the deformation model coinciding. Step S4 of the method is therefore carried out on the premise that the functional elements which correspond to one another remain arranged on one another, in particular aligned with one another.

Another condition can be that the functional element of the CAD model and the functional element of the deformation model must not fall apart or deviate from one another. Consequently, this further condition, according to which the predetermined geometry feature of the CAD model and the predetermined Special geometry element of the deformation model are arranged next to one another, in particular congruently, if the functional element of the CAD model and the functional element of the deformation model coincide for or during the alignment of the CAD model and the deformation model or remain arranged next to one another or congruently. Furthermore, the further or second condition is met if the two functional elements coincide due to the alignment of the CAD model and the deformation model.

This condition can be specified as an alternative or in addition to the condition or the other conditions. Since the CAD model and the deformation model are aligned with one another under the condition that the functional elements do not fall apart or differ from one another during alignment, the provision of the print model, in particular the effort involved in aligning the CAD model and the deformation model with one another, is particularly simple or low-effort.

According to a further advantageous embodiment of the method, an auxiliary production element of the CAD model and a corresponding auxiliary production element of the deformation model are determined in order to align the CAD model and the deformation model with one another, in order to align the CAD model and the deformation model with one another at the auxiliary production elements.

Accordingly, the special geometry element can alternatively or additionally be the auxiliary production element of the component. In this case, the special geometry element is of particular importance for the production of the component. For example, the production aid element or a multiplicity of production aid elements is provided on the green part in order to promote the production of the component. For example, the (respective) production aid element can be a support structure in order to support the green part or at least elements thereof during or after the application of the material powder and binder layers. For example, the green part can have a (for example horizontal) material projection which, due to its own mass, would break off from the green part or at least be deformed without additional support. By means of the support structure, which is also called a support structure, such a material projection can be supported on the contact level, for example on the printing bed or a surface of a heat treatment furnace. In this case, this material projection can be supported during the application of the material powder and binding agent layers and/or during the heat treatment. It is particularly provided that the support structure or Support structure is removed after the heat treatment of the component, for example by means of a material-separating or cutting separation process. This means that the auxiliary printing element or the support structure is no longer important for the functionality of the finished component. Furthermore, it is conceivable that the desired functionalities are provided by the component when the component has been freed from the corresponding auxiliary production element.

First of all, the auxiliary production element of the CAD model and the auxiliary production element of the deformation model are ascertained or determined. Thereafter, the CAD model and the deformation model are aligned with one another, with the production aid element of the CAD model and the production aid element of the deformation model coinciding. Step S4 of the method is therefore carried out on the premise that the auxiliary production elements that correspond to one another remain arranged on one another, in particular aligned with one another.

Another condition can be that the auxiliary production element of the CAD model and the auxiliary production element of the deformation model must not fall apart or deviate from one another. Consequently, this further condition, according to which the predetermined geometrical element of the CAD model and the predetermined geometrical element of the deformation model are arranged next to one another, in particular congruently, is met if the auxiliary production element of the CAD model and the auxiliary production element of the deformation model are used for or during the alignment of the CAD Model and the deformation model coincide or remain arranged congruently or together. Furthermore, this condition is met if the auxiliary production elements coincide due to the alignment of the CAD model and the deformation model.

This condition can be specified as an alternative or in addition to the condition or the other conditions. By aligning the CAD model and the deformation model with one another under the condition that the auxiliary manufacturing elements do not fall apart or deviate from one another during alignment, the provision of the print model, in particular the effort involved in aligning the CAD model and the deformation model with one another, becomes even easier or less complex.

According to an advantageous development of the method, step S4 takes place, in which

CAD model and the deformation model are aligned to each other by a

reducing the local deviation amounts at the predetermined geometry minutiae is prioritized higher than reducing the local deviation amounts away from the special geometry elements, for example on other geometry elements. A respective local deviation is characterized in particular by a corresponding deviation amount. A first priority is therefore assigned to reducing the local deviations occurring on the special geometry elements--for or when aligning the CAD model to the deformation model--a second priority being assigned to reducing the local deviations away from the special geometry elements. Here, the first priority is higher than the second priority. Due to such a prioritization of the alignment, it follows that the CAD model and the deformation model are aligned with each other primarily - i.e. according to the first priority - on the special geometry elements and subordinately - i.e. according to the second priority - on the other geometric elements are aligned with each other. In other words, it is provided that, for example by means of the best-fit algorithm, a deviation amount that is formed from the local deviation amounts at the special geometry elements is primarily minimized by the alignment, with another deviation amount sum that is formed from the local deviation amounts at the other geometry elements is formed, is minimized subordinately when aligning.

This results in the advantage that the special geometry elements, which are of particular importance for the functionality and/or for the production of the component, are arranged particularly accurately or precisely on one another, in particular congruently.

It has also proven to be advantageous in the method if a (first) permissible tolerance amount is specified for the respective local deviation amount at least between the respective predetermined special geometry element of the CAD model and the corresponding special geometry element of the deformation model. Furthermore, a loop comprising steps S2, S3 and S4 is carried out iteratively until the respective local deviation amount at the respective predetermined special geometry element corresponds to the (first) permissible tolerance amount. In particular, a first iteration model of the component is generated for this purpose before the print model is generated--for example in a step S4a--by the CAD model being changed or modified on the basis of the local deviation amounts. The iteration model is fed to step S2 for a first repetition and for further repetitions of the loop. This means that for the first iteration, the loop involves simulating the heat treatment against the iteration model, creating an iteration deformation digital model of the part to be manufactured. The loop also includes comparing the CAD model with the iteration deformation model, whereby the local deviation amounts between the iteration deformation model and the CAD model are determined. In addition, the loop includes aligning the iteration deformation model and the CAD model, thereby minimizing the total error amount formed from the local error amounts between the iteration deformation model and the CAD model. The loop of the method also includes step S4a, in which a further iteration model of the component is generated by changing or modifying the first iteration deformation model based on the local deviation amounts. The further iteration model is then fed to step S2 of the loop for a further repetition of the loop, etc.

In this case, it is provided in particular that the permissible tolerance amount is specified for the entire component, that is to say over the entire CAD model. In other words, it is provided that the external dimensions of the component correspond to the permissible tolerance amount after its heat treatment. By executing the loop of the method iteratively until the local deviations correspond to the allowable tolerance amount, the CAD model and the deformation model are aligned particularly precisely.

In this context, it has proven to be particularly advantageous for the method if a further or second permissible tolerance amount, which is larger, is specified for the respective local deviation amount at least between one of the other geometric elements of the CAD model and the other geometric element of the deformation model that corresponds to it than the first allowable tolerance amount. Thus, the second, larger amount of tolerance is allowed between the other geometry features (which are generally not geometry features herein), with the first, smaller or tighter amount of tolerance being allowed between the geometry features. This means that the CAD model and the deformation model (or possibly the iteration deformation model) are aligned more precisely at the geometry features than off the geometry features.

As a result, the effort involved in aligning the CAD model and the deformation model and, as a result, in providing the print model is again advantageously reduced. Since the special geometry elements are of primary importance for the functionality and/or for the production of the component, a complex and particularly precise alignment of the models apart from the special geometry elements can be carried out - i.e for example on the other geometric elements - can be dispensed with in order to increase the efficiency of the process. Nevertheless, simple manufacturability and the functionalities provided by the component remain guaranteed.

Furthermore, according to a further advantageous embodiment of the method, before step S2, in which the heat treatment is simulated using the CAD model and the deformation model (or possibly the iteration deformation model) of the component to be manufactured is generated, the CAD model is generated based on an expected or .probable deformation scaled. In other words, before the simulative heat treatment or before the simulative sintering—for example in a step S1a—a scaled CAD model is generated. In this case, the scaling takes place, in particular, translationally along one or more of the three spatial directions x, y, z. A scaling factor, by which the CAD model is scaled, emerges, for example, from internal experiments, for example from previous heat treatments of at least similarly designed green parts with similar or the same parameters (temperature, duration, etc.) of the corresponding heat treatment. In this way, the outlay for the method is further reduced since, due to the scaling of the CAD model, the deformations are already roughly compensated for before the heat treatment is simulated.

As a result, the effort, in particular the computing or simulation effort, for generating the deformation model or the iteration deformation model is reduced. Furthermore, the effort involved in determining the deviation amounts and in aligning the CAD model and the deformation model with one another is reduced. Accordingly, the effort involved in providing the print model is reduced overall. Step S1a can be part of the iteratively executable loop S10 (see above).

According to a second aspect of the invention, a method for additively manufacturing a component is proposed. In this manufacturing method, a material of the component to be manufactured is arranged according to a digital print model of the component. Furthermore, in the manufacturing process, the material is joined to form the component by means of heat treatment, in particular by means of sintering. The digital print model is provided using a method designed according to the above description. In particular, it is provided that an intermediate product or green part of the component is produced using binder jetting 3D printing. The invention also includes developments of the production method according to the invention, which have features as have already been described in connection with the developments of the method according to the invention for providing the digital print model. For this reason, the corresponding developments of the manufacturing method according to the invention are not presented again here.

The invention also includes the combinations of features of the described embodiments.

An exemplary embodiment of the invention is described below. For this shows:

1 shows a flowchart to clarify a method for providing a digital print model, wherein a component can be produced additively using the print model;

2 is a schematic view of a CAD model;

3 shows a schematic view of a deformation model;

4 is a schematic view of a process in which the CAD model and the deformation model are compared with each other;

FIG. 5 shows a schematic view of the comparison from FIG. 4 in a detailed view V; FIG.

Fig. 6 is a schematic view of the pressure model and

7 shows a schematic view of a process in which the CAD model and the manufactured component are compared with one another.

The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention to be considered independently of one another, which also develop the invention independently of one another and thus also individually or in a combination other than that shown Part of the invention are to be considered. Furthermore, the embodiment described can also be supplemented by further features of the invention already described.

Elements with the same function are each provided with the same reference symbols in the figures.

FIG. 1 shows a flowchart to illustrate a method A for providing a digital print model 1 (see FIG. 6), it being possible for a component 2 (see FIG. 7) to be produced additively using the print model 1. Furthermore, a method B for additively manufacturing the component 2 is illustrated by the flowchart in FIG. 1 . For the following, method A is considered a part of method B. Procedures A, B are described together. Where necessary, the differences between methods A and B are discussed. If reference is only made to “a method” or “the method” (without a reference number), the associated statements apply to methods A and B considered individually or in combination.

For the production of the component 2, for example by means of method B, it is provided that an intermediate product is first produced by means of 3D printing, in particular by means of binder jetting 3D printing, using the digital printing model 1. The intermediate product, which can also be referred to as a green part, is produced by alternately arranging material powder layers and binder layers, with the respective binder layer being applied selectively to a respective material powder layer according to the printing model 1 . The result is the intermediate product or green part, which is made up of alternating layers of material powder or binder. Accordingly, the material powder layers are bonded to one another by means of the binder. Next, powder elements of the respective material powder layer are glued together.

It is preferred if a material connection is formed directly between the material powder layers and not only indirectly, that is to say not only by means of the binder. For this purpose it is provided that the intermediate product is heat-treated. For example, the green part is sintered, creating a direct material connection between the powder elements of the respective material powder layer and a direct material connection between the material powder layers. Furthermore, the binder is at least partially dissolved or expelled from the intermediate product by sintering, for example by liquefaction, evaporation or sublimation. As a result, the intermediate product is deformed / deformed. Due to the deformations caused by sintering, a component produced in this way (not shown) does not correspond or does not correspond sufficiently to specifications that are specified by the target Geometry or by a CAD model 3 of the component 2 are specified. This is where procedure(s) A and/or B intervene.

In a first step S1 of the (respective) method, the digital CAD model 3 is provided, which is shown in a schematic view in FIG. 2 . For example, a designer uses suitable software or a CAD program to create the CAD model 3, which in this case has a target geometry of the component 2, i.e. information or data that indicates a desired shape and dimensions or relative dimensional ratios of the component 2 characterize.

In a further step S2, a heat treatment is simulated using the CAD model 3, as a result of which a digital deformation model 4 of the component 2 to be manufactured is generated, which is shown in a schematic view in FIG. The deformation model 4 has a deformation geometry or a deformed geometry of the component 2, the deformation geometry and the target geometry differing from one another due to deformations. The result of the simulative heat treatment are the deformations that would occur in reality on the component 2 if the intermediate product were printed using the CAD model 3 and then sintered.

It is conceivable that the CAD model 3 is roughly scaled before the heat treatment is simulated (ie before step S2). For this purpose, the method has a further step S1a before step S2, in which a scaled CAD model 3a is generated. A scaling factor by which the CAD model 3 is scaled emerges from internal experiments, by means of which previous heat treatments of at least similarly designed green parts were examined. In particular, the scaling factor is greater than one, that is to say the scaled CAD model 3a is larger than the CAD model 3. The scaling takes place, for example, translationally along one or more of the three spatial directions x, y, z. It is also conceivable that a separate scaling factor is determined for each of the spatial directions x, y, z, it being possible for the respective separate scaling factor to be greater than one, smaller than one or equal to one. In other words, the CAD model 3 can be scaled in the respective spatial direction x, y, z with a different scaling factor, as a result of which the scaled CAD model 3a is created. Alternatively or additionally, the scaling or the generation of the scaled CAD model 3a includes a respective rotation about one or more of the three spatial directions x, y, z. The method steps described below can be used in relation to the CAD model 3 and/or in relation to the scaled CAD model 3a. Therefore, for the following description no longer explicitly differentiates between the CAD model 3 and the scaled CAD model 3a.

In a step S3 of the method, the CAD model 3 and the deformation model 4 are compared with one another. 4 shows a schematic view of a process in which the CAD model 3 and the deformation model 4 are compared with one another, as a result of which local deviations 5 between the CAD model 3 and the deformation model 4 are determined. The local deviations 5 are shown schematically in the detailed view V or in FIG. The respective deviation 5 has a deviation amount 6, for example a straight deviation length 7 and/or a deviation angle 8. To determine or determine the deviation amounts 6, the CAD model 3 and the deformation model 4 are, for example, roughly superimposed, for example using the CAD program.

A further step S4 of the method follows, in which the CAD model 3 and the deformation model 4 are aligned with one another in such a way that a total deviation amount, which is formed by adding the local deviation amounts 6, becomes minimal. For example, for this purpose the deformation model 4 is moved translationally and/or rotationally in relation to the CAD model 3 until the total amount of deviation has become as small as possible. In particular, a best-fit algorithm is used here. The two models 3, 4 are considered to be best aligned with one another when the total amount of deviation, ie a sum of all local amounts of deviation 6, is minimal. To this extent, the total amount of deviation is reduced or minimized by aligning the models 3, 4 with one another—in particular using the best-fit algorithm.

The alignment of the CAD model 3 and the deformation model 4 with one another takes place here with at least one condition 100, according to which a predetermined special geometry element 9 of the CAD model 3 and a corresponding special geometry element 10 of the deformation model are arranged particularly close to one another—if possible congruently. Step S4 of the method is therefore carried out in such a way that the special geometry elements 9, 10 which correspond to one another remain arranged close to one another, in particular aligned with one another, with condition 100 being/is fulfilled. Consequently, the total deviation amount formed from the local deviation amounts 6 becomes minimal while complying with this condition 100. The digital print model 1 and consequently the finished component 2 comprises at least the specified special geometry element 9, 10, which is of particular importance for the production and/or for the functionality of the component 2. The respective special geometry element 9, 10 is specified here, for example by the designer of the component 2 identifying and marking the special geometry elements 9, 10 as such when creating the CAD model 3. The respective special geometry element 9, 10 is, for example, a respective point 11, a respective (even or odd) edge 12, a respective corner 13 and/or a respective (even or uneven) surface 14 of the component 2 or .of the CAD model 3.

In Fig. 3 and in Fig. 4, a zero deformation point 15 of the component 2 and the respective model 3, 4 is shown. A particularly low degree of deviation occurs at the zero deformation point 15 during sintering or heat treatment. In particular, the zero deformation point 15 is free from deviation. The zero deformation point 15 and a contact plane 16, over which the green part is set up, for example for the heat treatment, coincide. The zero deformation point 15 is therefore at the same height as the contact plane 16 in relation to a height of the green part. In addition, the zero deformation point 15 is congruent with the center of gravity of the green part in relation to a width and a length of the green part. The same applies when the finished sintered or heat-treated component 2 is considered: The zero deformation point 15 lies in a contact plane 16 of the component 2 and is congruent with the center of gravity of the component 2 with regard to a width and a length of the component 2. This applies to the CAD model 3 as well as for the deformation model 4. Accordingly, the zero deformation point 15 can be regarded as a common point of the component 2.

The condition 100 can have a further condition 101, according to which the zero deformation point 15 of the CAD model 3 and the zero deformation point 15 of the deformation model 4 must not fall apart or deviate from one another when the models 3, 4 are aligned. Here, the zero deformation point 15 can be considered as a special geometry element 9, 10. Consequently, condition 100, according to which the predetermined special geometry element 9, 10 of the CAD model 3 and the corresponding special geometry element 9, 10 of the deformation model 4 are arranged next to one another, can be condition 101. It is also conceivable that condition 101 is part of condition 100 . The condition 101 is met when the zero deformation points 15 coincide due to the alignment of the CAD model 3 and the deformation model 4 . In the present case, condition 100 has a further condition 102 or is formed by condition 102 . Condition 102 determines that when the models 3, 4 are aligned, a functional element 17 of the CAD model 3 characterizing a functionality of the component 2 and a functional element 18 of the deformation model 4 corresponding thereto are determined in order to determine the CAD model 3 and the deformation model 4 to the functional elements 17, 18 to align with each other. In particular, the special geometry element 9, 10 is designed as the functional element 17, 18. The special geometry element 9, 10 or the functional element 17, 18 is of particular importance for the functionality of the finished component 2. For example, the functional element 17, 18 is the surface 14. Furthermore, the functional element 17, 18 can be a hole or other material recess 23, such as a through hole or blind hole without a thread and/or provided with an internal thread, a Groove, etc. It is also conceivable that the functional element 17, 18 is designed as a cylindrical or polyhedral material projection, for example as a threadless and/or externally threaded pin or as another correspondingly designed material elevation. In particular, the functional element 17, 18 acts in the finished component 2 as a material, form and/or force-fitting element to form a material, form-fitting and/or force-fitting device, for example between the component 2 and another component, around the component 2 and to connect the other component materially, positively and/or non-positively to one another.

According to condition 102, the functional elements 17, 18 must not fall apart or deviate from one another when the models 3, 4 are aligned with one another. Condition 100, according to which the predetermined special geometry element 9, 10 of the CAD model 3 and the corresponding special geometry element 9, 10 of the deformation model 4 are arranged next to one another, can be condition 102. It is also conceivable that condition 102 is part of condition 100 . Condition 102 is met when, due to the alignment of CAD model 3 and deformation model 4, functional elements 17, 18 that correspond to one another coincide.

Alternatively or additionally, a further condition 103 is provided, according to which an auxiliary production element 19 of the CAD model 3 and a corresponding auxiliary production element 20 of the deformation model 4 are determined in order to align the CAD model 3 and the deformation model 4 with one another, in order to attach the models 3, 4 to the Manufacturing auxiliary elements 19, 20 to align with each other. The respective Auxiliary production element 19, 20 is produced, for example, during 3D printing of the intermediate product, in particular layered on from the same material powder as the intermediate product or component 2 itself. In the present case, the respective auxiliary production element 19, 20 is designed as an auxiliary printing element or as a so-called support structure, on the basis of which material projections, in particular material overhangs, can be produced by means of 3D printing. Furthermore, these material projections or overhangs do not break off during the sintering of the green part or intermediate product and/or do not deform if the material projections or overhangs are supported by the auxiliary production elements 19, 20. The production aid element 19, 20 is therefore of particular importance for the production of the component 2. The special geometry element 9, 10 can be designed as the production aid element 19, 20.

According to condition 103, the auxiliary production elements 19, 20 must not fall apart or deviate from one another when the models 3, 4 are aligned. Condition 100, according to which the predetermined special geometry element 9, 10 of the CAD model 3 and the corresponding special geometry element 9, 10 of the deformation model 4 are arranged next to one another, can be condition 103. It is also conceivable that condition 103 is part of condition 100 . The condition 103 is met when, due to the alignment of the models 3, 4 with one another, the auxiliary production elements 19, 20 which correspond to one another coincide.

The conditions 100, 101, 102, 103 are applicable individually or in any combination of one or more of the conditions 100, 101, 102, 103 simultaneously or sequentially in any order in the method to minimize a burden of step S4, in which the models 3, 4 are aligned with each other. By the respective condition 100, 101, 102, 103 already defining at least one respective point or at least one respective section of the two models 3, 4 to be aligned with one another, the effort for aligning the CAD model 3 with the deformation model 4 and thereby an effort to provide the print model 1. For this purpose, the CAD model 3 and the deformation model 4 are only aligned with one another to the extent that the at least one condition 100, 101, 102, 103 is met. In other words, during the alignment or as a result of the alignment, the total amount of deviation is only minimized to the extent that the at least one condition 100, 101, 102, 103 is met. As an alternative or in addition to the respective condition 100, 101, 102, 103, reducing the deviations 5 or deviation amounts 6 in the special geometry elements 9, 10 is assigned a first, high priority. A second, lower priority is assigned to reducing the local deviations 5 away from the special geometry elements 9, 10—in particular on other geometry elements 21, 22. Accordingly, the CAD model 3 and the deformation model 4 are primarily aligned with one another—according to the first or high priority—at the special geometry elements 9 , 10 and secondarily—according to the second, low priority—at the other geometry elements 21 , 22 . The other geometry elements 21, 22 are elements of the CAD model 3 that are of very little, in particular no, importance for the manufacture and for the functionality of the component 2. A deviation amount sum, which is formed from the local deviation amounts 6 on the special geometry elements 9, 10, is primarily minimized or reduced by the alignment, with another deviation amount sum, which is formed from the local deviation amounts 6 on the other geometry elements 21, 22, when Align is minimized or reduced subordinate.

In particular, a first permissible tolerance amount is specified for the respective amount of deviation 6 at least between the respective special geometry element 9 of the CAD model 3 and the corresponding special geometry element 10 of the deformation model 4 . Furthermore, in the present example, a second permissible tolerance amount is specified for the respective local deviation amount 6 between the other geometric elements 21 of the CAD model 3 and the corresponding other geometric element 22 of the deformation model 4 . The second allowable tolerance amount is greater than the first allowable tolerance amount. Consequently, when aligning the models 3, 4, a higher tolerance is permitted on the other geometric elements 21, 22 than on the special geometry elements 9, 10 others due to the different allowable tolerance amounts.

The method has a loop S10, which includes at least steps S2, S3 and S4. Loop S10 is repeated at least once, that is to say it is run through at least once more after it has been run through for the first time, with step S2, for example, following step S4 for repeating steps S2, S3, S4. In particular, the loop S10 is carried out iteratively until the respective deviation amount 6 at the special geometry elements 9, 10 corresponds to the first permissible tolerance amount. For this purpose, the method has a step S4a before the generation of the pressure model 1, in which, after step S4 has been run through for the first time, a first iteration model of the component 2 is generated by the CAD model 3 being changed or modified using the deviation amounts 6 . Then, when executing loop S10, the iteration model is fed to step S2. In particular, loop S10 has steps S1a, S2, S3, S4 and S4a, step S1a following step S4a for repeating steps S1a, S2, S3, S4 and S4a.

This means that for the first repetition of loop S10, the first iteration model generated in step S4a is fed to step S1a of loop S10, in which the first iteration model is optionally scaled to form a scaled first iteration model. The first (possibly scaled) iteration model is then provided to step S2 of loop S10, in which the first iteration model is heat-treated or sintered in a simulative manner. A first iteration deformation model is thereby generated, which is compared with the CAD model 3 in step S3 of the loop S10 and the deviation amounts between the CAD model 3 and the iteration deformation model are determined. In step S4 of loop S10, the iteration deformation model and the CAD model 3 are aligned with one another, with the total deviation amount formed from the deviation amounts 6 between the iteration deformation model and the CAD model 3 becoming minimal. In this case, one or more of the conditions 100, 101, 102, 103 are met. Loop S10 also includes step S4a, in which a second iteration model is created for a second repetition of loop S10 by changing or modifying the first iteration deformation model using local deviation amounts 6 . The second iteration model is then fed to step S1a of the loop for one more iteration of the loop.

For the iterative execution of loop S10, this includes--for example as a sub-step of step S4a--a test in which the respective amount of deviation 6 at the special geometry elements 9, 10 is checked for compliance with the first permissible tolerance amount. In particular, the test includes checking the respective amount of deviation 6 away from the special geometry elements 9, 10—ie, for example, on the other geometric elements 21, 22—for compliance with the second permissible tolerance amount. If the check establishes that at least the first tolerance amount is complied with, loop S10 is terminated and the method, for example after step S4, is continued with a further step S5. In step S5 of the method, the print model 1 of the component 2 to be manufactured is now generated. For this purpose, the CAD model 3 is changed or modified using the local deviation amounts 6 . The digital print model 1 is therefore based on the CAD model 3 , which was changed/modified using the deviation amounts 6 that occurred between the CAD model 3 and the deformation model 4 . If loop S10 was run through or executed at least once before step S5, digital print model 1 is based on CAD model 3, which was changed/modified using deviation amounts 6 that occurred between CAD model 3 and the iteration deformation model.

Fig. 6 shows a schematic view of the print model 1, which is deformed compared to the CAD model 3 and compared to the deformation model 4 in such a way that when the intermediate product that has been produced according to the print model 1 is sintered, the intermediate product or green part deformed so that the shape of the component 2 is formed.

Method B differs from method A in a step S6, in which the digital print model 1 is provided to a production unit, in particular a binder jetting 3D printer. The intermediate product or green part of the component 2 is then actually produced by means of the 3D printer and using the print model 1 . Step S6 also includes the (real) sintering of the green part, as a result of which the component 2 is produced.

FIG. 7 shows a process, for example a quality assurance process, in a schematic view, in which the CAD model 3 and the manufactured component 2 are compared with one another. This means that the component 3 is checked, for example measured, to what extent the actually produced component 2 corresponds to the shape stored in the CAD model 3 . It can be seen here that the component 2 follows the CAD model 3 particularly precisely at the special geometry elements 9, that is to say has particularly small tolerances. It can also be seen that the component 2 follows the CAD model 3 less precisely on the other geometric elements 21, since a larger tolerance was allowed on the other geometric elements 21 than on the special geometric elements 9.

Overall, the invention shows how particularly efficiently and precisely a deformation occurring on important elements of the component 2 as a result of a heat treatment is compensated for. Here, the method focuses on the compensation of special geometric elements of the component 2, namely the special geometric elements 9, 10. Although method A, B has been described here in connection with an additive manufacturing method, it should be understood that method A, B can also be used for other manufacturing methods in which heat is introduced into the corresponding component or into a corresponding intermediate product, such as when welding.

The invention is based on the idea of not specifying a particularly complex and precise tolerance at points on the component 2 that are unimportant for the production and the functionality of the component 2 . Instead, a distinction is made between the (important) special geometric elements 9, 10 and the (less important or unimportant) other geometric elements 21, 22 in the design and/or production of the component 2. A particularly narrow tolerance range is then specified only for the important special geometry elements 9, 10, while larger tolerances are permitted for the other unimportant geometric elements 21, 22.

reference number

A Method of providing a digital print model

B Process for the additive manufacturing of a component

1 print model

2 component

3 CAD model

3a scaled CAD model

4 deformation model

5 deviation

6 Deviation Amount

7 deviation length

8 deviation angles

9 geometry special element

10 geometry special element

11 point/node

12 edge

13 corner

14 area

15 zero deformation point

16 insurgency level

17 functional element

18 functional element

19 crafting aid element

20 Crafting Aid Element

21 other geometry element

22 different geometry element

23 material recess

100 condition

101 condition

102 condition

103 condition 51 process step

S1a method step

52 process step

53 process step

54 process step

S4a method step

55 process step

56 process step

S10 loop

Claims

PCT/EP2021/081182

Claims Method (A) for providing a digital print model (1) on the basis of which a component (2) can be produced additively, wherein

51 a CAD model (3) of the component (2) to be manufactured is provided;

52 a heat treatment is simulated using the CAD model (3), whereby a digital deformation model (4) of the component (2) to be manufactured is generated;

53 the CAD model (3) is compared with the deformation model (4), whereby local deviation amounts (6) between the CAD model (3) and the deformation model (4) are determined;

54 the CAD model (3) and the deformation model (4) are aligned with one another in such a way that a total deviation amount, which is formed from the local deviation amounts (6) between the CAD model (3) and the deformation model (4), becomes minimal;

55 the print model (1) of the component (2) to be manufactured is generated by the CAD model (3) being modified on the basis of the local deviation amounts (6); characterized in that the alignment of the CAD model (3) and the deformation model (4) with a condition (100, 101, 102, 103) takes place, according to which a predetermined geometry special element (9) of the CAD model (3) and a so that the corresponding special geometry element (10) of the deformation model (4) is arranged next to one another in such a way that the total deviation amount formed from the local deviation amounts (6) is minimal while complying with this condition (100, 101, 102, 103). Method (A) according to Claim 1, characterized in that a zero deformation point (15) of the CAD model (3) and a zero deformation point (15) of the deformation model (4) corresponding thereto are determined in order to convert the CAD model (3) and the Align the deformation model (4) at the zero deformation points (15) with one another. Method (A) according to Claim 1 or 2, characterized in that a functional element (17) of the CAD model (3) characterizing a functionality of the component (2) and a functional element (18) of the deformation model (4) corresponding thereto are determined, in order to align the CAD model (3) and the deformation model (4) on the functional elements (17, 18) with one another. Method (A) according to one of the preceding claims, characterized in that an auxiliary production element (19) of the CAD model (3) and a corresponding auxiliary production element (20) of the deformation model (4) are determined in order to form the CAD model (3) and to align the deformation model (4) on the auxiliary production elements (19, 20) with one another. Method (A) according to Claim 3 or 4, characterized in that step S4, in which the CAD model (3) and the deformation model (4) are aligned with one another, takes place by reducing the local deviation amounts (6) to the predetermined geometry special elements (9, 10) has a higher priority than reducing the local deviation amounts (6) apart from the geometry special elements (9, 10). Method (A) according to one of Claims 3 to 5, characterized in that for the respective local deviation amount (6) between the respective predetermined special geometry element (9) of the CAD model (3) and the special geometry element (10) of the deformation model ( 4) a permissible tolerance amount is specified and a loop S10 comprising steps S2, S3 and S4 is iteratively executed until the respective local deviation amount (6) on the respective predetermined special geometry element (9, 10) corresponds to the permissible tolerance amount. Method (A) according to Claim 6, characterized in that for the respective local deviation amount (6) between other geometric elements (21) of the CAD model (3) and the other geometric element (22) of the deformation model (4) corresponding thereto, a further permissible Tolerance amount is specified, which is greater than the allowable tolerance amount. Method (A) according to one of the preceding claims, characterized in that before step S2, in which a heat treatment is simulated using the CAD model (3), whereby the digital deformation model (4) of the component (2) to be manufactured is generated , the CAD model (3) is scaled based on an expected deformation. Method (B) for the additive manufacturing of a component (2), wherein a material of the component (2) to be produced is arranged according to a digital printing model (1) of the component (2), and the material is formed into the component (2) by means of a heat treatment is joined, characterized in that the digital print model (1) is provided by means of a method (A) designed according to one of Claims 1 to 8.