Method for the additive manufacturing of a three-dimensional workpiece and device for carrying out a method

Abstract

The invention relates to a method (100) for the additive manufacturing of a three-dimensional workpiece (2), with a device (1) for the additive manufacturing of a three-dimensional workpiece (2) from a thermoplastic material (20), wherein the thermoplastic material (20) is converted into a liquid phase by heating and is selectively applied to locations that are predetermined by the shape and dimensions of the workpiece (2) to be manufactured, wherein the workpiece (2) is built up layer by layer on a substrate carrier (5). It is characterized by the fact that when (120) a first layer (21) of the material (20) is applied to the substrate support (5) an at least partially positive-locking connection is created between a surface (50) of the substrate support (5) and the first layer (21) of the thermoplastic material (20). The invention further relates to a device for carrying out the inventive method for the additive manufacturing of a three-dimensional workpiece.

Description

[0001] The present invention relates to a method for the additive manufacturing of a three-dimensional workpiece and a device for carrying out the method for the additive manufacturing of a three-dimensional workpiece. State of the art

[0002] In additive manufacturing, or 3D printing, liquid or solid materials are built up layer by layer to create a three-dimensional workpiece. For example, thermoplastic materials, especially thermoplastic polymers, can be used, which are first liquefied by heating. The liquid material is then selectively applied to the areas where the workpiece is to be created. Upon cooling, the material solidifies again.

[0003] Some thermoplastic materials tend to shrink upon cooling. This shrinkage leads to variations in the dimensions of the finished workpiece. To counteract this, 3D printers with heated build chambers are known, allowing a constant temperature within the build chamber during the printing process. Once the printing process is complete, the build chamber is cooled in a controlled manner to allow the workpiece to cool and solidify. After cooling, the workpiece is removed, and a new printing process can be started by reheating the build chamber.

[0004] DE 10 2017 212 305 A1 discloses a 3D printer comprising a build chamber for accommodating a substrate carrier, on which the workpiece can be built layer by layer using a print head, and heating elements arranged within the build chamber for locally heating the workpiece. The heating element or heating system heats the substrate carrier such that a first layer of the material forms a solid bond with the substrate carrier.

[0005] The invention is based on the object of making the additive manufacturing of a three-dimensional workpiece from a thermoplastic material more efficient and thus more cost-effective, whereby the connection between the component and the substrate carrier is optimized. Disclosure of the invention

[0006] The object is achieved by the method according to the invention and the device for carrying out the method according to the invention.

[0007] The method for the additive manufacturing of a three-dimensional workpiece, with a device for the additive manufacturing of a three-dimensional workpiece from a thermoplastic material, wherein the thermoplastic material is converted into a liquid phase by heating and is selectively applied to locations that are predetermined by the shape and dimensions of the workpiece to be manufactured, wherein the workpiece is built up layer by layer on a substrate carrier.

[0008] According to the invention, when a first layer of the material is applied to the substrate carrier, an at least partially positive connection is produced between a surface of the substrate carrier and the first layer of the thermoplastic material.

[0009] The device for the additive manufacturing of a three-dimensional workpiece from a thermoplastic material liquefied by heating is preferably a 3D printer.

[0010] The method according to the invention ensures that an at least partially positive connection can be established between the surface and the first layer of the thermoplastic material, or the first printed layer of a component. This advantageously improves the quality of the components to be printed because warping of the component, or of the first layer on the substrate carrier, is avoided.

[0011] The thermoplastic material is a material for printing a component, or a printing material.

[0012] The substrate carrier can also be referred to as a printing plate or building plate. Quality degradations, such as deformation of the components, tend to occur in the area of ​​the printing plate, which is advantageously avoided by the method according to the invention.

[0013] Furthermore, the method according to the invention prevents unwanted detachment of the components from the substrate carrier, thereby advantageously preventing slipping, falling over, or displacement of the components from the substrate carrier. The at least partially positive connection ensures that the component does not adhere too tightly to the printing plate, thus advantageously preventing damage or destruction of the components upon removal from the printing plate, which can occur, for example, when the first layer is attached to the printing plate with adhesive.

[0014] A further advantage of the inventive method is that the adhesion of the first layer to the surface of the substrate carrier occurs independently of the material. A specific combination of printing material for the component and substrate carrier material is not necessary. This allows for the selection of lightweight materials, such as aluminum, for the substrate carrier, which advantageously reduces the weight of the substrate carrier and, if necessary, allows for the smaller design of the servo motors of an axis system of the device or 3D printer.

[0015] Furthermore, the process according to the invention also enables printing of polyolefins. Since these materials do not usually form adhesive bonds, the at least partially positive connection can advantageously ensure adhesion of the component to the substrate carrier.

[0016] In a preferred development, when applying the first layer of the material to the surface of the substrate carrier, an overdose of material is carried out by the print head in order to compensate for a corresponding amount of material which is received in recesses of the surface of the substrate carrier in order to produce an at least partially positive connection between the surface and the first layer of the thermoplastic material.

[0017] By using a substrate carrier with a surface that allows a form fit via recesses, adhesion of the first layer of the component to the surface is achieved in an advantageous manner.

[0018] In a first embodiment, this can be achieved, for example, by undercuts present in the recesses, wherein the material of the first layer can penetrate into the recess and, upon solidification by the undercuts, advantageously produces an at least partially positive connection.

[0019] In another embodiment, recesses have narrow contours, which can create adhesion or a partially positive connection through capillary action. During printing, the printable material flows into the recesses of the substrate carrier or the surface, whereby the first printed layer, and thus also the component, is at least partially positively bonded to the surface.

[0020] The overdosage of material by the print head compensates for the corresponding amount of material absorbed into the recesses in the surface of the substrate carrier, creating an at least partially positive connection between the surface and the first layer of thermoplastic material. As a result, the first layer is applied in such a way that it creates an at least partially positive connection and itself forms a nearly flat surface onto which the next layer to be printed is applied. This flat surface advantageously optimizes the strength and quality of the workpiece or component.

[0021] The overdosage of material by the print head to compensate for the amount of material within the build plate can be achieved, for example, by adjusting the speed of the print head.

[0022] In a further development, before the first layer of the material is applied to the substrate carrier by the print head, the substrate carrier is heated by a means for locally heating the workpiece to be manufactured.

[0023] The means for local heating are preferably heating elements arranged below or within the substrate carrier.

[0024] The means for local heating, or the heating elements, which are arranged below or within the substrate carrier, ensure targeted heating of the substrate carrier and thus of the surface, whereby the printing material can penetrate into the recesses of the surface, thereby advantageously producing the positive connection.

[0025] The means for local heating, or rather the heating elements arranged below or within the substrate carrier, also ensure easy removal of the component from the substrate carrier, since the positive locking can be released by heating the substrate carrier. This advantageously avoids the need for additional cleaning or coating of the substrate carrier before the printing process.

[0026] Local heating of the workpiece also advantageously ensures lower energy requirements of the device or the 3D printer, since the entire build space does not have to be heated. This is achieved by heating only the workpiece to be manufactured locally.

[0027] In a further development, the substrate carrier is heated by the means for locally heating the workpiece to be manufactured in such a way that the absorption of the material into the recesses of the surface is optimized.

[0028] The adjustability of the adhesion of the components to the substrate carrier or the build plate is achieved via various process parameters such as setting the temperature of the build plate and / or setting the temperature of the component material or the plastic and / or setting a nozzle distance between the print head and the substrate carrier and / or setting a volume flow during printing or extrusion.

[0029] The method according to the invention also enables optimized temperature management, since the optimized adhesion of the component to the substrate carrier allows the temperature of the substrate carrier to be lowered after just a few layers, which advantageously prevents, for example, degradation of the printed material. Heating the build plate is then no longer necessary, thus saving energy.

[0030] Furthermore, the invention comprises a device for the additive manufacturing of a three-dimensional workpiece for carrying out the method according to the invention for the additive manufacturing of a three-dimensional workpiece, wherein the device comprises a substrate carrier on which the workpiece can be built up layer by layer by a print head.

[0031] The substrate carrier has a surface configured such that a positive connection can be established, at least partially, between the surface and a first layer of the thermoplastic material. Furthermore, the surface of the substrate carrier has recesses into which the thermoplastic material can be at least partially introduced.

[0032] Furthermore, the device comprises means for optimising the at least partial positive connection between the surface and the first layer of the thermoplastic material, wherein the means are suitable for locally heating the workpiece.

[0033] Further measures improving the invention are presented in more detail below together with the description of the embodiments of the invention with reference to the figures. Short description of the drawing

[0034] They show: Fig. 1 A device for additive manufacturing of a three-dimensional workpiece according to the state of the art, Fig. 2 shows a device according to the invention for the additive manufacturing of a three-dimensional workpiece, Fig. 3 a detailed drawing of a first embodiment of a substrate carrier, Fig. 4 a detailed drawing of a second embodiment of a substrate carrier, Fig. 5 a flow diagram of a method according to the invention and Fig. 6 a flow diagram of a further development of the method according to the invention. Example

[0035] The Fig. The device 1 shown in Figure 1 for the additive manufacturing of a three-dimensional workpiece 2 from a thermoplastic material 20 liquefied by heating according to the prior art comprises a build chamber 3 for receiving a substrate carrier 5, on which the workpiece 2 can be built up layer by layer by a print head 4. Furthermore, means 6, 7 for locally heating the workpiece 2 are arranged within the build chamber 3.

[0036] The print head 4, which in this embodiment is designed as a piston extruder, applies the heated material 20 layer by layer to the substrate carrier 5. The substrate carrier 5 is movable at least in the vertical direction to enable the desired geometry of the workpiece 2 to be manufactured. Depending on the design of the device 1 or the 3D printer, the print head 4 or the substrate carrier 5 moves in the horizontal direction to enable the desired geometry of the workpiece 2 to be manufactured.

[0037] During the movement of the substrate carrier 5, accelerations occur that can cause the workpiece 2 to slip. To prevent this, a first means 6 for local heating is arranged below the assembly position of the workpiece 2, wherein this first means 6 is designed as a heating element arranged below the substrate carrier 5. The substrate carrier 5 is designed as a printing plate for receiving the three-dimensional workpiece 2. Depending on the structure and thickness of the substrate carrier 5, the heating element 6 can also be arranged within the substrate carrier 5.

[0038] A second means 7 for local heating is arranged above the substrate carrier 5, wherein the second means 7 is formed by at least one heat radiator. In the illustrated embodiment, the device 1 comprises two heat radiators.

[0039] Fig. 2 shows a device 1 according to the invention for the additive manufacturing of a three-dimensional workpiece 2 from a thermoplastic material 20 liquefied by heating, comprising a substrate carrier 5 on which the workpiece 2 can be built up layer by layer by a print head 4, wherein the substrate carrier 5 has a surface 50 which is designed such that a positive connection can be produced at least partially between the surface 50 and a first layer 21 of the thermoplastic material 20.

[0040] The device 1, or the 3D printer shown here, comprises the print head 4, which performs horizontal movements to print the first layer 21 of the workpiece 20 by dispensing the thermoplastic material 20, or the printing material. For this purpose, the printing material 20 is heated within the print head 4 by heating elements 43, and after melting, the first layer 21 is printed through a nozzle 41 onto the surface 50 of the substrate carrier 5, or the printing plate. A temperature sensor 42 arranged in the print head 4 measures the temperature of the printing material 20, or the melt, in order to monitor it and, if necessary, adjust it via the heating elements 43.

[0041] Furthermore, the 3D printer 1 comprises means 6 for optimizing the positive connection between the surface 50 and the first layer 21 of the thermoplastic material 20, wherein the means 6 are suitable for locally heating the workpiece 2. The means 6 for local heating are heating elements 6 arranged below or within the substrate carrier 5. The temperature set by the heating elements 6 within the substrate carrier 5 is measured and monitored by a temperature sensor 61.

[0042] If a target temperature deviates, the heating elements 6 are regulated accordingly.

[0043] Fig. 3 shows a detailed drawing of a first embodiment of a substrate carrier 5, wherein the surface 50 of the substrate carrier 5 has recesses 51 1-ninto which the thermoplastic material 20 can be at least partially introduced. The adhesion of the first layer 21 of the component 2 to the surface 50 of the substrate carrier 5 is achieved by the material 20 being pressed into the recesses 51 in the printing area. 1-n is introduced. Shown here in the recesses 513 to 517. The material 20 can, as shown here, completely fill the recesses 513 to 517 or alternatively only partially. The shown size ratio of the recesses 51 1-n within the surface 50 of the substrate carrier 5 to the first layer 21, or the thickness of the substrate carrier 5, serves only to illustrate the function. The recesses 51 1-n can be formed by microscopically small structures.

[0044] The recesses 51 1-nhave undercuts 53 behind which the material 20 flows, thereby creating an at least partially positive connection during solidification. In order to achieve a nearly flat surface 23 of the first layer 21, an overdose of material 20 by the print head 4 is necessary, wherein the overdose compensates for the corresponding amount of material 20 that is received in the recesses 513 to 517 of the surface 50 of the substrate carrier 5. The first layer 21 thus adheres via the material 20 within the recesses 513 to 517, wherein it does not adhere to the surface 50 of the substrate carrier 5. This creates the at least partially positive connection between the first layer 21 and the surface 50 of the substrate carrier 5. This creates a good connection so that the component 2 cannot detach from the substrate carrier 5 during printing.However, after completion of component 2, it can be easily separated from surface 50. This can be done with or without the activation of the in . Fig. 1 and Fig. 2 shown heating element 6.

[0045] Fig. 4 a detailed drawing of a second embodiment of the substrate carrier 5, wherein the surface 50 of the substrate carrier 5 recesses 52 1-n into which the thermoplastic material 20 can be at least partially introduced. The adhesion of the first layer 21 of the component 2 to the surface 50 of the substrate carrier 5 is achieved by the material 20 being pressed into the recesses 52 in the printing area. 1-n is introduced. Shown here in the recesses 525 to 52 14 . The material 20 can, as shown here, have the recesses 525 to 52 14 Completely or alternatively only partially fill. The size ratio of the recesses shown 52 1-nwithin the surface 50 of the substrate carrier 5 to the first layer 21, or the thickness of the substrate carrier 5, serves only to illustrate the function. The recesses 52 1-n can be formed by microscopically small structures.

[0046] The recesses shown here 52 1-n have narrow contours, whereby these can create a partially positive connection or adhesion via capillary action. During printing, the printable material 20 flows into the recesses 525 to 52 14 of the substrate carrier 5, or the surface 50, whereby the first printed layer 21 and thereby also the component 2 are at least partially positively connected to the surface 50.

[0047] In order to achieve a nearly flat surface 23 of the first layer 21, an overdose of material 20 by the print head 4 is also necessary for this embodiment, wherein the overdose compensates for the corresponding amount of material 20 that is in the recesses 525 to 52 14 the surface 50 of the substrate carrier 5. The first layer 21 thus adheres via the material 20 within the recesses 525 to 52 14 , whereby it does not adhere to the surface 50 of the substrate carrier 5. This creates the at least partially positive connection between the first layer 21 and the surface 50 of the substrate carrier 5. This creates a good connection that the component 2 cannot detach from the substrate carrier 5 during printing. After completion of the component 2, however, it can be easily separated from the surface 50. This can be done with or without the activation of the Fig. 1 and Fig. 2 shown heating element 6.

[0048] Fig. 5 shows a flow diagram of a method 100 according to the invention for the additive manufacturing of a three-dimensional workpiece 2 with a device 1 according to the invention, in which a thermoplastic material 20 is converted into a liquid phase by heating and is selectively applied to locations that are predetermined by the shape and dimensions of the workpiece 2 to be manufactured, wherein the workpiece 2 is built up layer by layer on a substrate carrier 5, wherein during the application 120 of a first layer 21 of the material 20 to the substrate carrier 5, an at least partially positive connection is produced between a surface 50 of the substrate carrier 5 and the first layer 21 of the thermoplastic material 20.In a next step, during the application 120 of the first layer 21 of the material 20 to the surface 50 of the substrate carrier 5, an overdose 130 of material 20 is carried out by the print head 4 in order to compensate for a corresponding amount of material 20 that is present in the recesses 51. 1-n , 52 1-n the surface 50 of the substrate carrier 5 in order to produce an at least partially positive connection between the surface 50 and the first layer 21 of the thermoplastic material 20.

[0049] The overdosage of material 20 by the print head 4 compensates for the corresponding amount of material 20 that is in the recesses 51 1-n , 52 1-nthe surface 50 of the substrate carrier 5 in order to create an at least partially positive connection between the surface 5 and the first layer 21 of the thermoplastic material 20. As a result, the first layer 21 is applied in such a way that it creates an at least partially positive connection and itself forms a nearly flat surface 23 onto which the next layer to be printed is applied. The flat surface 23 ensures optimization of the strength and quality of the workpiece 2 or the component.

[0050] The overdosage of material 20 by the print head 4 to compensate for the amount of material within the build plate 5 can be achieved, for example, by adjusting the speed of the print head 4.

[0051] Fig.6 shows a flow diagram of a further development of the method 100 according to the invention for the additive manufacturing of the three-dimensional workpiece 2 with a device 1 according to the invention, in which the thermoplastic material 20 is converted into a liquid phase by heating and is selectively applied at locations that are predetermined by the shape and dimensions of the workpiece 2 to be manufactured, wherein the workpiece 2 is built up layer by layer on the substrate carrier 5, wherein before the application of the first layer 21 of the material 20 to the substrate carrier 5 by the print head 4, the substrate carrier 5 is heated by means 6 for local heating 110 of the workpiece 2 to be manufactured and during the application 120 of the first layer 21 of the material 20 to the surface 50 of the substrate carrier 5, an overdosage 130 of material 20 is carried out by the print head 4 in order to compensate for a corresponding amount of material 20 that is in the recesses 51 1-n , 521-n the surface 50 of the substrate carrier 5 in order to produce an at least partially positive connection between the surface 50 and the first layer 21 of the thermoplastic material 20.

[0052] The adjustability of the adhesion of the first layer 21, or of the components 2 on the substrate carrier 5, or the building plate is achieved via various process parameters such as, for example, setting the temperature of the building plate 5 and / or setting the temperature of the component material 20, or of the plastic and / or setting a nozzle distance between the print head 4 and the substrate carrier 5 and / or setting a volume flow during printing or during extrusion. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 212 305 A1

[0004]

Claims

[1] Method (100) for the additive manufacturing of a three-dimensional workpiece (2), comprising a device (1) for the additive manufacturing of a three-dimensional workpiece (2) from a thermoplastic material (20), wherein the thermoplastic material (20) is converted into a liquid phase by heating and is selectively applied to locations which are predetermined by the shape and dimensions of the workpiece (2) to be manufactured, wherein the workpiece (2) is built up layer by layer on a substrate carrier (5), characterized by that when applying (120) a first layer (21) of the material (20) to the substrate carrier (5), an at least partially positive connection is produced between a surface (50) of the substrate carrier (5) and the first layer (21) of the thermoplastic material (20). [2] Method (100) according to claim 1, characterized bythat when applying (120) the first layer (21) of the material (20) to the surface (50) of the substrate carrier (5), an overdose (130) of material (20) is carried out by the print head (4) in order to compensate for a corresponding amount of material (20) which is deposited in recesses (51 1-n , 52 1-n ) of the surface (50) of the substrate carrier (5) in order to produce an at least partially positive connection between the surface (50) and the first layer (21) of the thermoplastic material (20). [3] Method (100) according to one of the preceding claims, characterized by that before the first layer (21) of the material (20) is applied to the substrate carrier (5) by the print head (4), the substrate carrier (5) is heated by a means (6) for locally heating (110) the workpiece (2) to be manufactured. [4] Method (100) according to claim 3, characterized bythat the substrate carrier (5) is heated by the means (6) for locally heating the workpiece (2) to be manufactured in such a way that the material (20) is received in the recesses (51 1-n , 52 1-n ) of the surface (50) is optimized. [5] Device (1) for the additive manufacturing of a three-dimensional workpiece (2) for carrying out a method for the additive manufacturing of a three-dimensional workpiece (2) according to one of the preceding claims.

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