DE102020122934A1 - Additive manufacturing process - Google Patents

Abstract

The invention relates to a computer-implemented additive manufacturing method for producing a three-dimensional object with at least one material layer. In particular, the invention relates to a computer-implemented 3D printing method for producing a three-dimensional object with at least one material layer. A production system with at least two simultaneously moving application heads for applying the at least one material layer of the three-dimensional object is used for the production, the at least one material layer being divided into several partitions and being applied in the divided partitions. The invention also relates to a computer-aided production system for a additive manufacturing process and a computer program which includes instructions corresponding to the process, and a computer-readable medium with this computer program.

Description

The invention relates to a computer-implemented additive manufacturing method for producing a three-dimensional object with at least one material layer. In particular, the invention relates to a computer-implemented 3D printing method for producing a three-dimensional object with at least one material layer.

The invention also relates to a computer-aided production system for an additive manufacturing method, in particular a 3D printing method, for producing a three-dimensional object with at least one material layer.

The invention also relates to a computer program, which includes instructions corresponding to the method, and a computer-readable medium with this computer program.

In additive manufacturing, the layered structure is computer-controlled from one or more liquid or solid materials according to specified dimensions and shapes. Additive manufacturing processes are also becoming increasingly widespread in the series production of parts.

Proceeding from this, it is the object of the invention to provide an improved additive manufacturing method. In particular, faster additive manufacturing is to be made possible with a constant or reduced number of application heads.

This object is achieved by the subject matter of patent claim 1 and the independent claim. Preferred developments can be found in the dependent claims.

• - Analysieren, mittels eines Analysesystems des Produktionssystems, eines dreidimensionalen Objektmodells des herzustellenden Objekts;
• - Partitionieren, mittels eines Partitionssystems des Produktionssystems, des Objektmodells in eine Partitionsmatrix mit mehreren Partitionen mit einer jeweiligen Partitionsgeometrie und Bestimmen der jeweiligen Partitionsgeometrie abhängig von Objektmodell-Eigenschaften und den Auftragsköpfen, wobei eine maximale Seitenlänge zumindest eines Teils der Partitionen kürzer als eine maximale Seitenlänge der Materialschicht ist;
• - Zuordnen, mittels eines Zuordnungssystems des Produktionssystems, jeder Partition zu einem Auftragskopf;
• - Bestimmen, mittels eines Bestimmsystems des Produktionssystems, eines Bewegungspfads und eines dem Bewegungspfad zugeordneten Zeitintervalls eines der Auftragsköpfe für jede der Partitionen; und
• - Ansteuern, mittels eines Ansteuersystems des Produktionssystems, der Auftragsköpfe zum Auftragen von der zumindest einen Materialschicht innerhalb der jeweiligen Partition.

According to claim 1, a computer-implemented additive manufacturing method, in particular a 3D printing method, is provided for producing a three-dimensional object with at least one material layer. A production system with at least two simultaneously moving application heads for applying the at least one material layer of the three-dimensional object is used for the production, the at least one material layer being divided into several partitions and being applied in the divided partitions. The manufacturing process has at least the following process steps:

• - Analyzing, by means of an analysis system of the production system, a three-dimensional object model of the object to be produced;
• - Partitioning, by means of a partition system of the production system, the object model into a partition matrix with several partitions with a respective partition geometry and determining the respective partition geometry depending on object model properties and the order headers, with a maximum side length of at least some of the partitions being shorter than a maximum side length of the material layer is;
• - Assigning, by means of an assignment system of the production system, each partition to an order header;
• - determining, by means of a determination system of the production system, a movement path and a time interval associated with the movement path of one of the job headers for each of the partitions; and
• - Controlling, by means of a control system of the production system, the application heads for applying the at least one layer of material within the respective partition.

According to the independent claim, a computer-aided production system for an additive manufacturing method, in particular 3D printing method, for producing a three-dimensional object with at least one material layer is provided.

The production system has: at least two simultaneously movable application heads for applying the at least one material layer of the three-dimensional object in at least two partitions of the material layer; an analysis system for analyzing a three-dimensional object model of the object to be manufactured; a partition system for partitioning the object model into the at least two partitions with a respective partition geometry and determining the respective partition geometry based on object model properties and the job headers; a mapping system for mapping each partition to a job header; a determination system for determining a path of travel and a time interval associated with the path of travel of one of the job headers for each of the partitions; and a control unit for controlling the application heads for applying the at least one material layer within the respective partition.

Above all, the manufacturing process and the production system enable a layer of material to be produced more quickly than with known additive manufacturing processes. This is because, for example, the movements of the application heads can be coordinated more easily. The order heads can be coordinated more easily, for example, because the partitions are divided up as desired. They can be of any shape and within a layer of material to be manufactured, the partitions can be under vary in size and shape. It is particularly advantageous here that a maximum side length of at least some of the partitions is shorter than a maximum side length of the material layer. The partitions are thus of any geometric shape. This significantly reduces the effort involved in synchronizing the movement paths of the application heads when applying material. Less synchronization effort is also required than with known additive manufacturing methods.

In particular, it can also be made possible to carry out the manufacturing method, for example with a 3D printer with multiple application heads, with the printer being able to recognize problems and continue printing even if an error has occurred, even in the event of faults, for example faults in the application heads . If an error occurs, for example, the method steps of partitioning and one or more of the subsequent method steps can be carried out again.

The additive manufacturing process is in particular a three-dimensional printing process. The three-dimensional printing process can be a melt layering process, also known as fused deposition modeling (FDM) or fused filament fabrication (FFF). With the additive manufacturing process, a three-dimensional object can be produced.

In the additive manufacturing process or in the production system, at least two application heads are used simultaneously to apply material. In principle, the use of N application heads is possible, where N is a natural number. In the method, the number of application heads used, i. H. of those application heads which are used for applying material, for example depending on an application head functionality and an unimpeded mobility of the application heads.

The application heads are preferably moved simultaneously. However, they are moved independently of each other. Provision can be made for the movement paths of the application heads for applying the material layer to be defined for an x-axis and a y-axis, which correspond to the two main axes of extent of the material layer. In particular, the x and y axes are mutually perpendicular axes. For the application heads themselves, for example, a further direction of movement in a z-axis perpendicular to the x- and y-axis can be programmed into their control electronics. The movements of the guns, i. H. their trajectories depend on the properties of the partition within which they deposit material. The properties of the partition include the location of the partition in the material layer, material properties, geometry, which may also include thickness.

The production system is in particular a 3D printer. The application heads for additive application in a production system designed as a 3D printer are then print heads.

The print heads actuated simultaneously can print a multi-dimensional object. In a simplest embodiment, the three-dimensional object is a simple layer of material, i. H. one layer and not several layers on top of each other. The single layer of material can be printed onto a sheet of paper, for example as a colored layer. Particularly preferably, the print heads are provided for printing a three-dimensional object which is layered, i. H. Material layer by material layer, is printed. When applying the material layer, at least one material layer of a material is applied in each case.

The individual systems of the production system, i. H. the analysis system, the partition system, the allocation system, the determination system and the control system can all be realized by a common control unit of the production system, which executes the method steps of the manufacturing method.

The object model to be produced can be a technical three-dimensional drawing, such as a CAD file.

Each order head is assigned a single partition per order loop, which the order head processes, i. H. according to the properties of the partition, such as its shape in particular. The partition thus corresponds to a material layer of the material applied by the gun in a plane for producing the object in a specified area of a material layer. The assignment between partition and order header is therefore clear for each material layer. After the partition is completed, the gun can be assigned to another partition of the same material layer or to a partition of a different material layer. Alternatively, the application head can be assigned to a plurality of partitions of a material layer. In such a case, a partition of the material layer is created by the application head in one application loop and further partitions are created by the application head in one or more subsequent application loops.

Preferably, all partitions of a material layer together form the material layer in its entirety. In other words, when all the partitions are placed together, they form a closed surface of the layer of material.

The production system has at least two application heads, preferably at least four application heads.

A layer of material is preferably not created in a common application loop. In other words, preferably no closed layer of material is produced in an application loop in which the application heads apply material within the partitions. In particular, partitions of a layer of material that are adjacent to one another are not fabricated in a build loop.

The partition matrix includes the complete object, which is segmented by the partitions of the partition matrix. All partitions spatially next to each other then form the complete partition matrix. The partition matrix can be two-dimensional. In this case we are dealing with flat partitions of a flat object. The partition matrix can be three-dimensional. In this case, the partition matrix forms a three-dimensional object with all of its partitions.

When determining a partition, a two-dimensional partition geometry is specified. The partition geometry is defined in a two-dimensional coordinate system, for example in the case of only one layer of material being applied. To apply material within a partition, the application heads can be moved in several, but at least one x- and one y-direction of the surface extension direction of the material layer

The object model properties include, for example, the following: a material from which the object is made, a length of time required for the deposited material to solidify, a geometry of the object. In determining the partition based on the guns, consideration may be given to: a number and location of the guns, e.g. B. on a traverse, a working speed of the application heads. Specifically, the partition geometry is set separately for each partition based on the previous properties.

The maximum side length of at least part of the partitions can be shorter than a maximum side length of the material layer. It is also conceivable that all partitions have a maximum side length that is shorter than the maximum side length of the material layer. The aforementioned side length ratios exist, for example, when the material layer is divided into partitions in the longitudinal direction and in the transverse direction, so that the partitions together form a grid-like, in other words matrix-like, structure on the material layer. The partitions can have any geometric shape to form the lattice-like structure.

Associating the partitions with one of the guns means that each partition is uniquely assigned to a gun and the assigned gun has material to apply in one of the job loops in that partition. The assignment can be changed under certain conditions.

The movement path and the movement time interval can be determined for one or more order loops. The movement path and the movement time interval can be defined for a single material layer of a single layer object, for a single material layer of a multilayer object, for multiple material layers of a multilayer object, for multiple objects, e.g. B. when these are connected to each other by the manufacturing process, or are determined for a complete object with all its material layers. Each of the layers of material is made with one or more application loops. An order loop always includes a time interval that is uniquely assigned to the order loop, within which one or more application heads are controlled for applying material in one partition per application head. Each of the order loops is thus executed in a different time interval. An integer multiple of or at least one partition(s) is filled with material per order loop. The time it takes the gun to apply material in the partition is a time interval. In particular, that time interval of the partition also corresponds to the time length of the order loop which is the longest. This means, in particular, that partition within which the material application takes the longest also determines the maximum length of the respective application loop.

The activation of the order heads for a material order within a respective partition can, for example, take place separately for each of the order loops. Then, after the end of a job loop, it would be checked whether all job heads are still functional. If this is the case, the application heads for applying material could be controlled within a next partition. Otherwise, ie if it is determined, for example, that one of the application heads is no longer functional, a new movement path and a corresponding time interval can be set for all other application heads that are still functional vall be determined for still missing partitions of the material layer. Checking whether the application heads are still functional can also be carried out while material is being applied. Particular preference is always given to renewed partitioning of the object model whenever one or more application heads are inoperable or there is another fault affecting the application of material. Subsequent steps, ie the assignment, the determination and the activation, can then be carried out again.

According to a modified embodiment, it is provided that the partitioning of the object model into the partition matrix with the plurality of partitions includes an overlapping of at least two of the partitions. The benefit of overlapping is that it solidifies the object as it is being made. The partition overlapping can be performed with any of the partitions. Then each partition has at least one overlap with another partition. Rotating and/or enlarging one or more partitions is conceivable, for example, to produce an overlap between the partitions. Additionally or alternatively, it is also conceivable for one or more partitions to be shifted in one or more directions. Overlapping can be implemented for partitions of superimposed layers of material.

Side edges of superimposed partitions of superimposed material layers preferably run in opposite directions at an angle to one another. In particular, straight lines which in each case form a side edge of a partition in sections have opposite gradients in the case of material layers lying on top of one another. An oppositely sloping design, in particular with an opposite straight line gradient, can be used to obtain the same manufacturing time for the respective material layer, with better strengthening of the manufactured object being achieved at the same time, in particular between the individual material layers of the object. For superimposed layers of material of corresponding size, with side edges of the partitions of the respective material layers running in opposite directions at an angle to one another, a corresponding production time is also achieved.

• ◯ bei Partitionen verlaufen Partition-Seitenkanten schräg zueinander,
• ◯ bei übereinanderliegenden Partitionen verlaufen Partition-Seitenkanten schräg zueinander,
• ◯ bei übereinanderliegenden Partitionen übereinanderliegender Materialschichten verlaufen Partition-Seitenkanten schräg zueinander,
• ◯ bei Partitionen übereinanderliegender Materialschichten verlaufen Partition-Seitenkanten schräg zueinander,
• ◯ bei Partitionen ist zumindest eine Ecke einer Partition zu einer Seitenkante einer anderen Partition auf Stoß ausgerichtet,
• ◯ bei übereinanderliegenden Partitionen ist zumindest eine Ecke einer Partition zu einer Seitenkante einer anderen Partition auf Stoß ausgerichtet,
• ◯ bei Partitionen übereinanderliegender Materialschichten ist zumindest eine Ecke einer Partition zu einer Seitenkante einer anderen Partition auf Stoß ausgerichtet,
• ◯ bei übereinanderliegenden Partitionen übereinanderliegender Materialschichten ist zumindest eine Ecke einer Partition zu einer Seitenkante einer anderen Partition auf Stoß ausgerichtet.

According to a preferred embodiment, it is provided that the overlapping of at least two of the partitions of the object model includes that in the case of partitions, in particular superimposed ones, in particular superimposed material layers, partition side edges run obliquely to one another; and/or the overlapping of at least two of the partitions of the object model comprises that in the case of partitions, in particular superimposed ones, in particular superimposed material layers, at least one corner of one partition is butt-aligned with a side edge of another partition. The preferred embodiment thus includes the following alternatives, among others:

• ◯ in the case of partitions, partition side edges run at an angle to each other,
• ◯ in the case of partitions lying on top of one another, the side edges of the partitions run diagonally to one another,
• ◯ in the case of overlying partitions of overlying material layers, partition side edges run at an angle to each other,
• ◯ in the case of partitions of superimposed layers of material, partition side edges run at an angle to one another,
• ◯ in the case of partitions, at least one corner of a partition is aligned to a side edge of another partition,
• ◯ in the case of partitions on top of each other, at least one corner of one partition is aligned to a side edge of another partition,
• ◯ in the case of partitions made of superimposed layers of material, at least one corner of one partition is aligned to a side edge of another partition,
• ◯ in the case of overlying partitions of overlying layers of material, at least one corner of one partition is butt-aligned with a side edge of another partition.

The overlaps as specified according to the embodiment described above have been found to be particularly effective in strengthening the manufactured object. In particular, the only constraint between overlapping partitions of always different layers of material is a slope of the boundaries, i. H. the edges, the partitions. In particular, the alignments of corners and side edges of a partition of a first material layer are not restricted in relation to alignments of corners and side edges of a partition of a second material layer.

According to a modified embodiment, it is provided that a production system control unit transmits at least control signals for controlling the application heads to one or more of the application heads and receives feedback signals about the operating state of the application heads, and the production system control unit with one or more sensors at least feedback signals about the operating state of the respective sensors; and/or the method a Ver has a driving step of checking whether at least one of the application heads is functionally impaired, and if at least one of the application heads is functionally impaired, at least the method steps of assigning, determining and controlling for application heads that are not functionally impaired are carried out.

As a result, it is possible to react flexibly to disruptions and at the same time a consistently good, reproducible quality of the manufactured object can be favored. The production system control unit can be implemented by a local processor or an external processor or a combination thereof. The control signals can be transmitted to the respective application head for one or more application loops. The operational status feedback signals may include information regarding the operational readiness of the gun, such as e.g. B. a functional impairment. The operating status information can also include a status of the application of material. The feedback signals about the operating state of the respective sensor can include measured values of the sensor, for example measured values of a flow sensor or a filament sensor. In particular, any feedback signals about the operating status of the sensor are taken into account, via which a status or statuses of one or more application heads can be determined. The guns can be functionally impaired if the material output unit, e.g. an extrusion head for dispensing molten filament material. In general, a gun can be considered functionally impaired if the gun would produce the manufactured product incorrectly in its allocated partition.

• ◯ Zuordnen jeder Partition zu einem Auftragskopf;
• ◯ Bestimmen eines Bewegungspfads und eines dem Bewegungspfad zugeordneten Zeitintervalls eines der Auftragsköpfe für jede der Partitionen; und
• ◯ Ansteuern der Auftragsköpfe zum Auftragen von der zumindest einen Materialschicht innerhalb der jeweiligen Partition.

A functional impairment can be determined in a communication between the respective application head and a central control unit of the production system. Alternatively or additionally, the production system has one or more sensors for measuring a material flow, or generally a material output, on one or more application heads. These sensors communicate with the central control unit. For example, the sensors can be a flow sensor or a filament sensor. Such sensors can be provided for each of the application heads. If at least one of the application heads is functionally impaired, at least the following procedural steps are carried out for application heads that are not functionally impaired:

• ◯ associating each partition with a job header;
• ◯ determining a trajectory and a time interval associated with the trajectory of one of the guns for each of the partitions; and
• ◯ Controlling the application heads for applying the at least one layer of material within the respective partition.

The activation of the application heads for applying the at least one layer of material within the respective partition can take place directly after checking whether there is a fault in at least one of the application heads.

• ◯ Zuordnen jeder Partition zu einem Auftragskopf;
• ◯ Bestimmen eines Bewegungspfads und eines dem Bewegungspfad zugeordneten Zeitintervalls eines der Auftragsköpfe für jede der Partitionen; und
• ◯ Ansteuern der Auftragsköpfe zum Auftragen von der zumindest einen Materialschicht innerhalb der jeweiligen Partition.

According to a modified embodiment of the invention, it is provided that if at least one of the application heads is functionally impaired, the method steps of analyzing the three-dimensional object model of the object to be produced are carried out for the application heads that are not functionally impaired; and partitioning the object model into the at least two partitions with the respective partition geometry and determining the respective partition geometry based on the object model properties and the job headers. Alternatively, it can be provided that for the non-functionally impaired application heads only the method step of partitioning the object model into the at least two partitions with the respective partition geometry and determining the respective partition geometry based on the object model properties and the application heads is carried out. In this case, the object model is partitioned again without a previous analysis. It can be selected, for example, depending on the design of the object, whether it is only partitioned or analyzed again and then partitioned. After analyzing and partitioning or after merely partitioning, the following is preferably done again:

• ◯ associating each partition with a job header;
• ◯ determining a trajectory and a time interval associated with the trajectory of one of the guns for each of the partitions; and
• ◯ Controlling the application heads for applying the at least one layer of material within the respective partition.

• Ein Sicherheitsabstand (SD) wird definiert, welcher beim Auftragen in Unterpartitionen eingehalten werden muss. Folgende zwei Anforderungen können gestellt werden:
  1. 1. Wenn eine Unterpartition mit anderen Unterpartitionen auf der linken und rechten Seite gleichzeitig kollidiert, muss eine Breite der Unterpartition größer oder gleich SD sein.
  2. 2. Wenn eine Unterpartition mit anderen Unterpartitionen an der Ober- und Unterseite zur gleichen Zeit kollidiert, muss die Höhe der Unterpartition größer oder gleich SD sein.
• Aufgrund dieser Anforderungen müssen Partitionen der Materialschicht zwei weitere Anforderungen erfüllen:
  1. 1. Wenn eine Partition gleichzeitig links und rechts mit anderen Partitionen kollidiert, muss die Partitionsbreite größer oder gleich 2*SD sein, andernfalls muss die Partitionsbreite größer oder gleich SD sein.
  2. 2. Wenn eine Partition gleichzeitig mit anderen Partitionen in der Ober- und Unterseite kollidiert, muss die Partitionshöhe größer oder gleich 2*SD sein, andernfalls muss die Partitionshöhe größer oder gleich SD sein.

According to a modified embodiment, it is provided that the determination of a movement path and a time interval associated with the movement path of one of the application heads for each of the partitions includes determining whether the application heads collide during application. Determining collisions favors one from the other the independent movement of the application heads. Determining whether the guns are colliding during dispensing may include checking whether partitions within which material is being dispensed are a safe distance from one another. The safety distance can be determined depending on the object size and/or depending on the application heads. For example, a collision determination for a material layer with four partitions, which in turn are each divided into four sub-partitions, can be performed as follows. A subpartition is a part of a partition. The subpartition is always smaller than the partition of which it is a part:

• A safety distance (SD) is defined, which must be observed when applying to sub-partitions. The following two requirements can be made:
  1. 1. When a sub-partition collides with other sub-partitions on the left and right at the same time, a width of the sub-partition must be greater than or equal to SD.
  2. 2. If a sub-partition collides with other sub-partitions at the top and bottom at the same time, the height of the sub-partition must be greater than or equal to SD.
• Because of these requirements, material layer partitions must meet two additional requirements:
  1. 1. If a partition collides with other partitions left and right at the same time, the partition width must be greater than or equal to 2*SD, otherwise the partition width must be greater than or equal to SD.
  2. 2. If a partition collides with other partitions in the top and bottom at the same time, the partition height must be greater than or equal to 2*SD, otherwise the partition height must be greater than or equal to SD.

If it is determined that a collision cannot be avoided, for example if the requirements listed above cannot be met due to the size of the object, the arrangement of the guns must be changed. Alternatively or additionally, the number of application heads involved in applying material in the partitions of the material layer can also be reduced, with at least one or more application heads not moving and/or being in a parking position.

According to a modified embodiment, it is provided that a size of at least one of the partitions is determined according to the time interval for applying the at least one material layer within the respective partition and/or a size of at least one of the partitions is modified until it is determined that the application heads are being applied not collide. The embodiment has the advantage that planning of the application of material within the individual partitions is simplified. It can also be advantageous that no collisions take place between the application heads. The size of the partitions is selected in each case in such a way that the time for applying material within partitions from the application heads within an application loop is the same. Alternatively or additionally, partitions with mutually corresponding processing time for applying material can be distributed over the application loops.

According to a modified embodiment, it is provided that a start time of the time interval of each of the partitions is determined as a function of a length of the time interval compared to other time intervals of other partitions of the same material layer. This has the advantage that planning of material application within the individual partitions is simplified. For example, movement paths of individual application heads, e.g. B. from a parking position to a partition, can be better coordinated. The material layer can be applied within several application loops. For each job loop, a start time of the time interval assigned to the partition is specified for the partitions that are processed in the job loop. The starting point of each iteration of the additive manufacturing process does not need to be calculated. Each head informs the controller when the partition has completed, and the controller instructs it to proceed to the next partition when all heads have finished iterating. The production time of each partition is calculated and optimized (partitioning) when the partitions are created. However, it is no longer necessary during the manufacturing process of the partitions.

For example, a layer of material is said to have been divided into six partitions. Two functional application heads are available for processing, ie filling the partitions with material. Accordingly, three application loops are necessary to complete the layer of material. A starting point of the time interval corresponding to a starting point of the job loop can then be assigned to the individual partitions, for example. The time interval within which a partition is filled with material can vary between partitions. If the partitions are located within a material layer, this can be caused, for example, by different area sizes of the partitions. A different processing time, for example due to different layer thicknesses and/or different materials, can also be a cause. The start times Simultaneously processed partitions can then, for example, be synchronized or at least placed in a short period of time so that they are close together.

According to a modified embodiment, it is provided that the partitioning of the object model into the at least two partitions with the respective partition geometry and the determination of the respective partition geometry based on the object model properties and the order headers includes dividing strip-shaped partitions into sub-partitions, with the sub-partitions extending over a Extend partial length of the strip-shaped partitions. It can be useful to use computer-aided calculation programs that include a slicing algorithm, so that the material layer is already divided into strip-shaped partitions by this slicing algorithm. Based on this, the strip-shaped partitions, which at this point can still have a side length equal to the side length of the material layer, can be further subdivided into sub-partitions. These sub-partitions then in turn have a smaller side length than the side length of the material layer. In particular in the context of the description of the figures, the sub-partitions which were previously obtained from partitions of a slicing algorithm are also partitions. In other words, in connection with this application, partitions are always the smallest possible subdivision of the material layer within which material is applied in an application loop.

According to a modified embodiment, it is provided that after each completion of the material layer within the respective partition, the application head is moved to another position by at least one other application head in an unsynchronized manner.

In particular, a synchronization point is needed after creating partitions. Once this point is reached, the process of moving to the next partition can be performed by all the job heads at the same time without any additional synchronization points. An unsynchronized movement of the individual application heads is possible since the application heads are moved independently of one another. For example, moving a gun after completion can be to a park position, i. H. a position of the application head, which is safe from collisions with other application heads, take place. In particular, when collisions between guns must be avoided, there is no transition process from a completed partition to a position yet to be filled with material. For example, to avoid a collision, upon completion of dispensing in a partition of a zone, the gun(s) may be moved to a safe line/point that will allow each head to launch into the next zone without collisions. In particular, the application heads are synchronized for each layer of material to be produced. Subsequently, the application heads would then carry out an application of material within the individual partitions of the material layer, unsynchronized from one another.

The invention is explained in more detail below using a preferred exemplary embodiment with reference to the drawings.

• 1 schematisch eine Möglichkeit zur Aufteilung einer Materialschicht eines Objektmodells in einzelne Partitionen;
• 2 schematisch einen ersten Schritt eines Aufteilens eines Objektmodells gemäß einer weiteren Möglichkeit zur Aufteilung einer Materialschicht;
• 3 schematisch einen zweiten Schritt des Aufteilens des Objektmodells;
• 4 schematisch einen dritten Schritt des Aufteilens des Objektmodells;
• 5 schematisch einen vierten Schritt des Aufteilens des Objektmodells;
• 6 schematisch einen auf den vierten Schritt folgenden fünften Schritt, bei dem jeweils innerhalb einer Partition pro Hauptunterteilung der Materialschicht Material aufgetragen wird;
• 7 schematisch einen sechsten Schritt, bei dem jeweils innerhalb einer weiteren Partition pro Hauptunterteilung der Materialschicht Material aufgetragen wird;
• 8 schematisch einen siebten Schritt, bei dem jeweils innerhalb einer weiteren Partition pro Hauptunterteilung der Materialschicht Material aufgetragen wird;
• 9 schematisch einen achten Schritt, bei dem jeweils innerhalb einer weiteren Partition pro Hauptunterteilung der Materialschicht Material aufgetragen wird;
• 10 schematisch eine Aufteilung der Materialschicht, bei der ein Sicherheitsabstand zur Vermeidung von Kollisionen zwischen Auftragsköpfen nicht eingehalten werden kann;
• 11 schematisch eine Aufteilung der Materialschicht, bei der der Sicherheitsabstand zur Vermeidung von Kollisionen zwischen Auftragsköpfen eingehalten werden kann;
• 12 schematisch eine erste Aufteilung der Materialschicht mit schräg verlaufenden Partition-Seitenkanten;
• 13 schematisch eine zweite Aufteilung der Materialschicht mit schräg verlaufenden Partition-Seitenkanten;
• 14 schematisch eine Übersicht über Eingaben bzw. Eingabeparameter, Prozessschritte und Ausgaben bzw. Ausgabeparameter bei einem Verfahren gemäß einer Ausführungsform;
• 15 schematisch ein Produktionssystem gemäß einer Ausführungsform; und
• 16 schematisch ein Flussdiagramm eines Verfahrens gemäß einer Ausführungsform.

Show in the drawings

• 1 schematically a way of dividing a material layer of an object model into individual partitions;
• 2 schematically a first step of dividing an object model according to a further possibility for dividing a material layer;
• 3 schematically a second step of partitioning the object model;
• 4 schematically a third step of partitioning the object model;
• 5 schematically a fourth step of partitioning the object model;
• 6 schematically a fifth step following the fourth step, in which material is applied within one partition per main subdivision of the material layer;
• 7 schematically a sixth step, in which material is applied in each case within a further partition per main subdivision of the material layer;
• 8th schematically a seventh step, in which material is applied in each case within a further partition per main subdivision of the material layer;
• 9 schematically an eighth step, in which material is applied in each case within a further partition per main subdivision of the material layer;
• 10 Schematically a division of the material layer in which a safety distance to avoid collisions between application heads cannot be maintained;
• 11 schematically a division of the material layer, in which the safety distance to avoid collisions between application heads can be maintained;
• 12 schematically a first division of the material layer with inclined partition side edges;
• 13 schematically a second division of the material layer with inclined partition side edges;
• 14 schematically an overview of inputs or input parameters, process steps and outputs or output parameters in a method according to an embodiment;
• 15 schematically a production system according to an embodiment; and
• 16 schematically a flow chart of a method according to an embodiment.

In an additive manufacturing process, molten material is deposited layer by layer of material from the bottom to the top of the object, with each layer of material formed by extruded lines of material. Traditional slicing algorithms, for example, define a pattern for these lines to form each layer of material. The slicing algorithm then determines the printing order of the lines to reduce gun movement from the end of one line to the beginning of the next. Finally, in the normal operating state, ie without faults, several application heads 4 (see 15 , in which a schematic diagram to illustrate a mode of operation and in particular a communication between individual components of a production system is shown) during the printing process all the defined lines that make up each layer of material until the object is completely printed.

The computer-implemented additive manufacturing method according to a possible embodiment works together with a slicing algorithm, which is used for known additive manufacturing methods. After a line pattern of each layer of material is defined, according to the computer-implemented method, the line pattern is divided into different partitions so that the line pattern can be produced simultaneously by different guns. In this case, the lines of the line pattern form side edges of the partitions. When the partitions are defined, the lines which each partition has are sorted in order to keep the movement paths of the application heads 4 as short as possible.

In the case of multi-head printing, the possibility of collisions between application heads 4 should also be ruled out as far as possible. Each application head 4 must maintain a certain distance from another application head at all times. In order to achieve this, the method defines which partitions of the material layer are to be printed at the same time. These partitions have a defined distance from one another, at which it can be ensured that the application heads 4 can produce the partitions at the same time without collisions. Before the completion of a material order in a material layer is continued with the next layer of material, the application heads 4 are synchronized so that all application heads start the material application at the same time. Another goal of the algorithm is to distribute the production work evenly to the application heads 4. To achieve this, each partition that is to be printed at the same time must be printed in the same amount of time. Therefore, a gun 4 does not have to wait during the synchronization process to start printing the next partition, and the overall print time acceleration can be optimized.

In order to be able to use a division algorithm for partitioning with any partition sizes in the computer-implemented method, the application heads 4 must be able to move independently of one another in the X and Y axes. A mechanism for moving in a Z-axis can move for each application head 4 at the same time.

In 1 1 schematically shows a possibility of how a material layer of an object or object model can be divided into individual partitions. The arrangement of the application heads 4 is organized in rows in this exemplary embodiment. Each row consists of guns 4 and the number of guns per row can be different for each row. For example, an arrangement with three rows and two guns 4 in the first row, three in the second row and four in the last row as in 1 appearance.

To simplify the definition of an array, the array can be defined as an integer array specifying the number of guns 4 in each row. The previous example is then defined as: (2,3,4). The entire algorithm of the method can be performed by swapping the X and Y axes. Thus, the rows can be defined in each of the axes.

According to the exemplary embodiment, an object is printed material layer by material layer. It does not start crafting a layer of material before the previous one is finished. Application heads 4 moving in parallel apply material in partitions of the same layer of material and only change to the next layer of material when the previous one is completely produced. This is taken into account in the method according to In the exemplary embodiment, the work of a single layer of material is divided between the various applicator heads 4, this process being repeated for each layer of material in the object.

A possible embodiment of the method is based on the 2 until 13 as well as based on 16 be discussed.

According to a method step with the reference number "100" (see 16 ) an analysis takes place, by means of an analysis system of the production system, of a three-dimensional object model of the object to be produced.

Optionally, according to a method step with the reference number “150”, a check is carried out to determine whether at least one of the application heads 4 is functionally impaired. Checking can take place without analyzing. Checking can include the analysis system detecting, for example, an interference signal from one of the application heads 4 (see 15 ) receives and/or that the analysis system queries the application heads or one of the sensors associated with the application heads 4 as to whether there is a fault. If there is a fault, the subsequent method steps 200, 300, 400 and 500 are carried out again, even if they may have already been carried out beforehand.

According to a method step with the reference number "200", the object model is partitioned by means of a partition system of the production system into a partition matrix with several partitions with a respective partition geometry and determination of the respective partition geometry depending on object model properties and the order heads 4, with a maximum side length at least part of the partitions is shorter than a maximum side length of the material layer.

Once the line pattern of each material layer is obtained by a traditional slicing algorithm, subdivisions are defined. A possible example of such a subdivision is in 2 shown. In the 2 The subdivisions shown are line subdivisions. The divisions determine which partition of a single layer of material from each gun 4 according to a gun assembly, e.g. B. a printer is produced. When dividing into the partitions, the aim is to ensure that the time required to make each partition is equal. The metric used to calculate the work assigned to each job head 4 may differ in the implementation of the method. It can be calculated to give a real manufacturing time of the part using the line pattern and the configuration of the printer, e.g. B. taking into account its speed or acceleration, etc. to obtain.

In order to reduce a lot of the calculations required and the processing time involved, an alternative is to use the surface instead of the real manufacturing time. Two partitions with the same area are then printed in almost the same time. The small difference in the print time of the partitions does not make a big difference in the final print time and speed. Depending on the computer resources and the time spent on the cutting process, a metric is chosen. On the one hand, the real manufacturing time will take more resources and time, but achieve the optimal distribution. On the other hand, by using the area, a sufficiently approximate distribution is achieved without causing any work overload during the process. Other metrics can also be chosen, such as approximate print time, total length of lines, etc.

In the following, the work metric is denoted by the abbreviation "WM". First, the subdivisions for the lines of the gun array are defined. These divisions make the WM of each partition proportional to the number of guns 4 in the row. the 2 shows an example of a (2, 3) application head arrangement. The area with the reference number “1” corresponds to 2 WM and the area with the reference number “2” corresponds to 3 WM.

The subdivisions are defined independently for each row. According to a method step with the reference number “300”, each partition is assigned to an order header 4 by means of an assignment system of the production system.

Each partition obtained with these subdivisions is assigned an order header 4 so that they have the same WM. In 3 an example of a (2,3) gun assembly is shown. The subdivisions associated with the (2,3) gun assembly are major subdivisions.

According to a method step with the reference number “400”, a determination system of the production system determines a movement path and a time interval assigned to the movement path of one of the application heads 4 for each of the partitions.

According to a method step with the reference number “500”, activation takes place by means of a control system of the production system, the application heads 4 for applying the at least one layer of material within the respective partition.

With the main divisions, the production work can be divided equally between the application heads 4 of the arrangement. To reduce the chance of collisions, the printing process of one layer of material is divided into four stages. In each stage the application heads 4 print a partition of a part of the layer of material assigned to them. A safety distance is maintained between the partitions, so that material can be applied simultaneously within the partitions without collisions between the application heads 4. At the beginning of each stage the guns 4 are synchronized and wait until all guns 4 are ready to start the stage. In order to avoid performance losses in the manufacturing process, each applicator head 4 should complete the work in the same time. In this way, the WM of each partition will be similar. The partitions are defined by secondary subdivisions within the material layer portions obtained by the major subdivisions. First, horizontal divisions are calculated to get the same WM on each side, see this 4 . Second, vertical partitions are defined to have four partitions per part of the material layer with the same WM, see this 5 .

The order in which the partitions are filled with material is always the same in the exemplary embodiment: In the first stage, the partitions are printed at the top left (see 6 ). In the second stage, the partitions are printed out at the top right (see 7 ). In the third stage, the partitions are printed at the bottom left (see 8th ). In the fourth stage, the partitions are printed at the bottom right (see 9 ).

A safety distance SD from one another is maintained when partitions are printed at the same time. To ensure this, sub-partitions of the partitions must meet two requirements: If a sub-partition to be processed by an application head 4 collides with sub-partitions to the left and right that are also to be processed, the width of the sub-partition must be greater than or equal to the safety distance SD . If a sub-partition to be processed collides with other sub-partitions to be processed in the top and bottom at the same time, the height of the sub-partition must be greater than or equal to the safety distance SD.

Because of these requirements, partitions created by major divisions must meet two additional requirements: if a partition collides with other partitions on the left and right at the same time, the partition width must be greater than or equal to 2*SD, otherwise the partition width must be greater or be equal to SD. If a partition collides with other partitions in the top and bottom at the same time, the partition height must be greater than or equal to 2*SD, otherwise the partition height must be greater than or equal to SD.

If these requirements cannot be met due to the size of the object, the arrangement of the application heads 4 must be changed or the number of application heads 4 is reduced by some application heads 4 being stopped.

Under certain circumstances, for the even distribution of the WM to the application heads 4 in material layers with a small width and/or height, such as in 10 shown, an additional measure may be required. In this example of the divided material layer, the above conditions would not be met even if the divisions in the layer of the 10 split the World Cup evenly. To solve this, the side walls of the partitions are shifted until the requirements are met. A suitably partitioned layer of material, where the conditions are satisfied again after the sidewalls of the partitions have been moved, is in 11 shown.

In an object, as a rule, two consecutive layers of material are similar. Therefore, the parting lines defined by the method will likely be the same in two consecutive layers of material. If this is the case, the final object will not be stable enough due to the splits in the same position. To solve this, the parting lines used in a layer of material have a small slope. This slope is the same for all lines in a material layer. The dividing process in which the inclined lines divide the material layer can be the same process as the process for meeting the SD constraints. In the exemplary embodiment, the slope of the lines is inverted for each layer of material to ensure that there are not two similar lines in two consecutive layers of material. After the partitions have been completed, two layers of material lying on top of one another can be divided, as is the case in FIGS 12 and 13 is shown.

14 shows a schematic overview of inputs or input parameters (see reference “E”), process steps (see reference “P”) and outputs or output parameters (see reference “A”) in the method. to the inputs or input parameters include user commands, computer-aided design (CAD) files from which properties of the object model are determined, and errors, locations or states of the guns. In the process, the user commands are translated, the CAD files are divided into grids and sent to a production system for the additive manufacturing process, as well as processing data from the object's manufacturing process (see also 16 ). Here, after the method step “400” of determining, by means of a determination system of the production system, the movement path and the time interval assigned to the movement path of one of the application heads 4, a G-code file is created for each of the partitions from the CAD file. The G-code file is used in method step “500”, in which the application heads 4 are actuated to apply the at least one material layer within the respective partition. The 3D print of the object or the movements of the application heads 4 are received as output or output parameters.

15 12 schematically shows a production system according to an embodiment. The production system has the following components: a control unit 3, two application heads 4, a filament sensor 5, a flow sensor 6, a user interface 7, an external display 8, and a filament flow detector 9. The components of the production system transfer signals. The control unit 3 receives filament interference signals FS and start detection signals SE from the filament flow detector 9 , the filament flow detector 9 receiving signals S from the filament sensor 5 and the flow sensor 6 . The control unit 3 sends pressure signals D to the user interface 7, which can be displayed to a user via the external screen 8, for example. User commands BB can be queried via a command line prompt BE. The control unit 3 can continue to send 4 requests for further printing AW and G-code commands GB to each of the application heads. A signal can be sent from the respective application head 4 to the control unit 3 when the application head 4 is ready to continue printing BW.

Reference List

1

Area corresponding to a major subdivision of the material layer

2

Area corresponding to a major subdivision of the material layer

3

control unit

4

order header

5

filament sensor

6

flow sensor

7

user interface

8th

external screen

9

filament flow detector

A

output

B

commands

D

printer status

E

input

P

process

S

sensor signal

X

axis

Y

axis

Z

axis

AW

Prompt to continue printing

bb

user command

BE

Command line prompt

BW

Ready to continue printing

FS

filament noise

GB

G code commands

SD

safety distance

SE

start detection signal

WM

work metrics

Claims (13)

Computer-implemented additive manufacturing method, in particular 3D printing method, for producing a three-dimensional object with at least one material layer, wherein a production system with at least two simultaneously moving application heads (4) for applying the at least one material layer of the three-dimensional object is used for the production, wherein the at least one material layer is divided into several partitions and is applied in the divided partitions, the manufacturing method having at least the following method steps: analyzing (100), by means of an analysis system of the production system, a three-dimensional object model of the object to be manufactured; Partitioning (200), by means of a partition system of the production system, the object model into a partition matrix with a number of partitions with a respective partition geometry and determining the respective partition geometry depending on object model properties and the job heads (4), wherein a maximum side length of at least some of the partitions is shorter than a maximum side length of the material layer, assigning (300) each partition to an order header (4) by means of an assignment system of the production system; determining (400), by means of a determination system of the production system, a movement path and a time interval associated with the movement path of one of the job heads (4) for each of the partitions; and controlling (500), by means of a control system of the production system, the application heads (4) for applying the at least one layer of material within the respective partition. The method of the preceding claim, wherein partitioning (200) the object model into the partition matrix having the plurality of partitions comprises overlapping at least two of the partitions. Method according to the preceding claim, wherein the overlapping of at least two of the partitions of the object model includes that in the case of partitions, in particular one on top of the other, in particular material layers lying on top of one another, partition side edges run at an angle to one another; and or the overlapping of at least two of the partitions of the object model comprises that in the case of partitions, in particular superimposed ones, in particular superimposed material layers, at least one corner of one partition is aligned to a side edge of another partition in abutting manner. Method according to one of the preceding claims, wherein a production system control unit transmits at least control signals for controlling the application heads (4) to one or more of the application heads (4) and receives feedback signals about the operating state of the application heads (4), and wherein the production system control unit with one or more sensors at least feedback signals about the operating status of the respective sensors; and or the method has a method step of checking (150) whether at least one of the application heads (4) is functionally impaired, and if at least one of the application heads (4) is functionally impaired, at least the method steps of assigning (300), determining (400) and Activation (500) for non-functionally impaired application heads (4) are performed. Method according to the preceding claim, wherein, if at least one of the application heads (4) is functionally impaired, for the non-functionally impaired application heads (4) the method steps of analyzing (100) the three-dimensional object model of the object to be manufactured; and des Partitioning (200) the object model into the at least two partitions with the respective partition geometry and determining the respective partition geometry based on the object model properties and the order headers (4) to be executed; or wherein for the non-functionally impaired application heads (4) the method step of Partitioning (200) the object model into the at least two partitions with the respective partition geometry and determining the respective partition geometry based on the object model properties and the order headers (4). Method according to one of the preceding claims, wherein determining (400) a movement path and a time interval associated with the movement path of one of the application heads (4) for each of the partitions comprises determining whether the application heads (4) collide during application. Method according to one of the preceding claims, wherein a size of at least one of the partitions is determined according to the time interval for applying the at least one material layer within the respective partition and/or a size of at least one of the partitions is modified until it is determined that the application heads (4) do not collide when applied. Method according to one of the preceding claims, wherein a start time of the time interval of each of the partitions is determined depending on a length of the time interval in comparison to other time intervals of other partitions of the same material layer. Method according to one of the preceding claims, wherein the partitioning (200) of the object model into the at least two partitions with the respective partition geometry and the determination of the respective partition geometry based on the object model properties and the order heads (4) comprises a division of strip-shaped partitions into sub-partitions, wherein the sub-partitions extend over a partial length of the strip-shaped partitions. Method according to one of the preceding claims, wherein after each completion of the material layer within the respective partition the application head (4) is moved into a different position by at least one other application head (4) in an unsynchronized manner. Computer-aided production system for an additive manufacturing process, in particular 3D printing process, for producing a three-dimensional object with at least one material layer, the production system having: at least two simultaneously movable application heads (4) for applying the at least one material layer of the three-dimensional object in at least two partitions of the material layer ; an analysis system for analyzing a three-dimensional object model of the object to be manufactured; a partition system for partitioning the object model into the at least two partitions with a respective partition geometry and determining the respective partition geometry based on object model properties and the job headers (4); a mapping system for mapping each partition to a job header (4); a determination system for determining a movement path and a time interval associated with the movement path of one of the application heads (4) for each of the partitions; and a control unit for controlling the application heads (4) for applying the at least one material layer within the respective partition. A computer program comprising instructions which cause the production system of the preceding claim to carry out the method steps according to any one of Claims 1 until 10 executes Computer-readable medium on which the computer program according to the preceding claim is stored.

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