Hybrid manufacturing of 3D parts

Abstract

1. A method (100) for producing a three-dimensional object (1), comprising the steps of: providing (110) a three-dimensional mold (2) defining an internal space (21); introducing (120) a filling material (3) comprising at least one liquid or pasty monomer into the internal space (21); polymerizing (130) the monomer into a polymer, wherein the temperature (3a) of the filling material (3) and / or the temperature (2a) of the outer surface of the three-dimensional mold (2) are monitored (140); and evaluating (150) the quality (1a) of the object (1) based on the results (2a, 3a) of this monitoring and / or taking at least one measure (4) to guide (160) the temperature (2a, 3a) in a desired direction.

Description

[Technical Field]

[0001] The present invention relates to the manufacture of parts as a composite of a three-dimensional mold and a filler material. [Background technology]

[0002] 3D printing can be used to create three-dimensional objects of any shape. Most 3D printers build the object they are creating layer by layer, from the bottom up, by adding material to the object at each location within the layer that belongs to the object.

[0003] When building up a new layer, molten material is often placed on top of already solidified material. Therefore, the strength with which two layers adhere to each other is lower than that of a single layer against tensile or shear loads in the plane of the layers. Furthermore, 3D printing a solid mold can take a very long time. Therefore, Patent Document 1 discloses a 3D printing method in which the printed structure is filled with a monomer, which is then polymerized. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Patent Application Publication No. 102016222558 Summary of the Invention

[0005] Within the scope of the present invention, a method for manufacturing a three-dimensional object has been developed.

[0006] The method begins with providing a three-dimensional mold that defines an interior space. In particular, the three-dimensional mold can be a structure, for example, produced by 3D printing. This does not incur high tooling and tooling costs, making it particularly cost-effective for low-volume production, for example, with lot sizes in the single- or double-digit range.

[0007] A filler material containing at least one liquid or pasty monomer is introduced into the interior space. The monomer is polymerized into a polymer, and the temperature of the filler material and / or the temperature of the outer surface of the three-dimensional mold are monitored. Based on the results of this monitoring, the quality of the object is evaluated and / or at least one measure is taken to direct the temperature in a desired direction.

[0008] The polymerization of monomers into polymers proceeds optimally over a relatively narrow temperature range, but at the same time, for large volumes, the temperature of the filler material fluctuates widely during polymerization. For example, the polymerization of caprolactam into polyamide 6 proceeds optimally over a temperature range of 140-220°C.

[0009] At the same time, the temperature of the filler material must not be allowed to rise above the temperature at which the 3D mold softens or breaks. This would mean that it would no longer be possible to guarantee that the final object will have the exact shape predefined for the mold, for example during 3D printing. For polyamides, the limit for 3D printing mold materials is around 200°C. Furthermore, it is important to note that the polymerization is an exothermic reaction, generating heat of polymerization and heat of crystallization, the amount of which depends on the reaction rate.

[0010] The spatial variation of temperature can be exemplified by the example of a solid cup with a handle: heat can accumulate inside the cup and potentially overheat the filling material, whereas in the handle, heat from the interior must travel a much shorter distance to reach the outer surface.

[0011] Therefore, the assessment of the quality of an object is particularly important, e.g. How the temperature of the fill material was set throughout the area designated for polymerization; How much the temperature of the 3D model locally exceeds a given maximum (or falls below a given minimum), What temperature-time profile will the object be cooled with? · To what extent the temperatures of the fill material and / or the 3D mold deviate from the model-based determined predictions; The method can include determining:

[0012] The temperature-time profile determines the crystallinity and possible mechanical stress of the solidified fill material.

[0013] Although temperature deviations from the determined prediction do not have a direct physical effect on the quality of the object, they can indicate that the manufacturing process is not proceeding as planned in some respect. This raises at least a first suspicion that the quality of the part is also not as originally planned. For example, there may be a leak in the process or the object may be dirty. In the manufacturing equipment, for example, a heater may have broken down.

[0014] Alternatively or in combination with evaluating the quality of the object, the temperature can be actively steered in a desired direction, where the effective measures can depend, inter alia, on whether the temperature should be modified only locally in a specific range or globally, for example.

[0015] For example, the temperature of the oven in which the monomer is polymerized and / or the residence time of the object in the oven can be varied. In this way, the temperature can be modified particularly globally. Furthermore, since the object varies from the outside to the inside, it is preferable to be able to modify the temperature to some extent in the outer regions of the object.

[0016] For example, the temperature at which the monomer is introduced into the interior space of the three-dimensional mold can be varied. This also allows for global temperature modification. The temperature change propagates from the point where the monomer is introduced into the interior space.

[0017] The object can also be locally heated or cooled, for example. For local heating, for example, an infrared beam or a laser beam can be used. For local cooling, for example, an air nozzle can be used.

[0018] In a particularly advantageous embodiment, the temperature monitoring comprises measuring the temperature at multiple locations and determining the temperature of at least one other location of the filling material and / or the three-dimensional mold taking this temperature into account. The spatial distribution of the temperature can be taken into account, in particular, to indicate, for example, how complete the polymerization has been throughout the object. This is also crucial for the mechanical strength of the object, which must be demonstrated, for example, within the scope of quality control.

[0019] For example, the location where the temperature is to be measured can be scanned with an infrared thermometer, but it is also possible, for example, to make a thermograph of the object and extract the temperature to be measured from this thermograph.

[0020] The temperature of at least one other location in the filler material can be determined, in particular, for example using a parameterized model, the parameters of which are trained from measurements of temperatures at locations within the filler material, where the model is a sort of "digital twin" of the object, the temperature of which can be read anywhere within the object.

[0021] For training the model, for example, a test object can be created, which contains temperature sensors at specific locations in the interior space of a three-dimensional mold. When the filler material is introduced, the filler material flows into these temperature sensors, which cannot be removed after the filler material solidifies. Therefore, this type of temperature monitoring is typically not possible for objects designated for normal use or sale. However, if the model learns the relationship between temperatures measured at accessible locations and temperatures at inaccessible locations inside the filler material, measuring the temperatures at these accessible locations is sufficient to at least approximately determine the temperature profile inside the object. The model can, in particular, include a machine learning model, such as a neural network. When creating the model, existing know-how from conventional filling simulations, for example from injection molding, can be used.

[0022] In particular, when a three-dimensional mold is provided, for example, access can be left free for inserting a temperature sensor at a location in the interior space of the three-dimensional mold for the purpose of training a model, in which case there is no need to manually modify the three-dimensional mold.

[0023] In a particularly advantageous embodiment, when the three-dimensional mold is provided, the locations where the temperature is intended to be measured are marked and / or prepared. For example, a hole or recess can be introduced into the three-dimensional mold at these locations in order to locally reduce the wall thickness of the mold. The temperature measured at these locations then closely follows the temperature of the filling material.

[0024] In another advantageous embodiment, at least one location on the outer surface of the three-dimensional mold where a local maximum or minimum temperature is expected based on the mold geometry is selected as the location for temperature measurement. These temperatures are already persuasive in themselves, since in the context of polymerization it is primarily important to maintain the reaction temperature in a given passage. Locations that stand out in terms of local minimum or maximum temperature are, for example, the inner edges, holes, or areas of maximum wall thickness of the three-dimensional mold.

[0025] The present invention may be fully or partially computer-implemented and thus embodied in software. Accordingly, the present invention also relates to a computer program having machine-readable instructions that, when executed on one or more computers, cause the computer(s) and / or one or more computer-controlled manufacturing facilities to perform a method. In this regard, embedded systems and process controls, among others, capable of executing machine-readable instructions may also be considered computers.

[0026] The invention also relates to a download product comprising a machine-readable data carrier and / or a computer program, which is a digital product that can be transmitted over a data network, i.e. downloaded by a user of the data network, and which can be sold for instant download, for example in an online shop.

[0027] Furthermore, the computer may be equipped with a computer program, a machine-readable data carrier, or a downloadable product. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram of an embodiment of a method 100. FIG. [Figure 2] 1 is a cross-sectional view of a three-dimensional object 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] Other measures for improving the present invention will be explained in detail below with reference to the drawings together with a description of a preferred embodiment of the present invention.

[0030] FIG. 1 is a schematic flow chart of an embodiment of a method 100 for manufacturing a three-dimensional object 1 .

[0031] In step 110, a three-dimensional mold 2 is provided, which defines an interior space 21. According to block 111, a 3D printed structure can be provided as the three-dimensional mold 2.

[0032] In step 120, a filler material 3 comprising at least one liquid or pasty monomer is introduced into the interior space 21.

[0033] In step 130, the monomer is polymerized into a polymer while in step 140 the temperature 3a of the filling material 3 and / or the temperature 2a of the outer surface of the three-dimensional mold 2 is monitored.

[0034] Based on the results 2a, 3a of this monitoring, the quality 1a of the object 1 is assessed in step 150. Alternatively or in combination with this, at least one measure 4 can be taken in step 160 to guide the temperature 2a, 3a in a desired direction.

[0035] According to block 141, the temperature monitoring may involve measuring the temperatures 2a, 3a at a number of locations. Then, according to block 142, the temperature 2a of at least one other location of the filling material 3 and / or the three-dimensional mold 2 is determined taking these temperatures 2a, 3a into account. # , 3a # To this end, in particular for example according to block 112, when the three-dimensional mold 2 is provided, marking and / or preparation of the places where it is intended to measure the temperature can be carried out.

[0036] According to block 141a, in particular, at least one location 2a for temperature measurement can be selected, for example on the outer surface of the three-dimensional mold 2, where a local maximum or minimum value of temperature is expected based on the geometry of the mold.

[0037] According to block 142a, in particular, the temperature of at least one other location of the filling material 3 (2a # , 3a # ) can be determined using a parameterized model, the parameters of which are trained on the basis of measurements of temperatures at locations within the fill material 3. To facilitate these measurements for training the model, in particular, when the three-dimensional mold 2 is provided, for example according to block 113, access can be left free for inserting temperature sensors at predetermined locations in the interior space 21 of the mold 2.

[0038] The evaluation of the quality 1a of the object 1 can be carried out in particular by e.g. How the temperature 3a of the fill material 3 was set throughout the area designated for polymerization (block 151); How much the temperature 2a of the three-dimensional mold 2 locally exceeds a predetermined maximum (or falls below a predetermined minimum) (block 152), With what temperature-time profile will object 1 be cooled (block 153), How much the temperature of the filling material 3 and / or the three-dimensional mold 2 deviates from the model-based determined prediction (block 154), The method can include determining:

[0039] The measures 4 for inducing the temperatures 2a, 3a can be, in particular, e.g. Varying the temperature of the furnace in which the monomer is polymerized and / or the residence time of the object 1 in the furnace (block 161); and / or Varying the temperature at which the monomer is introduced into the interior space 21 of the three-dimensional mold (block 162), and / or Locally heating or cooling object 1 (block 163) may include:

[0040] FIG. 2 exemplarily shows a snapshot of the execution of the method 100 during filling of a three-dimensional mold 2 with a fill material 3. The three-dimensional mold 2 is shown in cross section and has an inlet 22 for the fill material 3 and three vents 23a-23c that allow air to escape from the mold 2, so that the three-dimensional mold does not experience resistance when filled with the fill material 3. Twelve measurement points a-l are marked on the outer surface of the three-dimensional mold 2. According to block 142 of the method 100, the temperature 2a of the outer surface of the mold 2 is measured at these measurement points a-l. Based on the temperatures measured at the locations a-l, according to block 142 of the method 100, the temperature 3a at each arbitrary location in the fill material 3 in the mold 2, here points m and n, is calculated. # Next, the temperature 2a measured directly on the outer surface of the mold 2 and the calculated temperature 3a at other locations in the filling material 3 can be calculated. # And, can be used to determine the quality 1a of the object 1 made up of the mould 2 and the filling material 3 in step 150 of the method 100; and / or Step 160 of the method 100 can be utilized to determine measures 4 for directing the temperature 2a of the outer surface of the mould 2 and / or the temperature 3a of the filling material 3 in a desired direction. [Explanation of symbols]

[0041] 1 3D object 1a quality 2 3D type 2a Outer surface temperature 3a Filling material temperature 2a # Temperature of different locations in the fill material 3a # Temperature of different locations in a 3D model 3 Filling material 4. Measures 21 Interior Space 23a~23c Bent 100 Method for manufacturing a three-dimensional object a~l Measurement points n, m points

Claims

1. A method (100) for manufacturing a three-dimensional object (1), comprising: a step (110) in which a three-dimensional mold (2) is provided that defines an interior space (21); a step (120) in which a filler material (3) comprising at least one liquid or pasty monomer is introduced into said interior space (21); - polymerizing (130) said monomers into a polymer; a step (140) in which the temperature (3a) of said filling material (3) and / or the temperature (2a) of the outer surface of said three-dimensional mould (2) is monitored; a step (150) in which the quality (1a) of said object (1) is assessed based on the results (2a, 3a) of said monitoring and / or a step (160) of taking at least one measure (4) to guide the temperature (2a, 3a) in a desired direction; It encompasses In the step (140) in which the temperatures (2a, 3a) are monitored, The temperature (2a, 3a) of at least one location of the filler material (3) and / or the three-dimensional mold (2) is measured (141), The measured temperatures (2a, 3a) are input to a machine learning model that has been previously trained based on temperatures of the filling material (3) previously measured within the interior space (21) to determine temperatures (2a #, 3a #) of at least one other location of the filling material (3) and / or the three-dimensional mold (2) that is different from the location (142), using the measured temperatures (2a, 3a) as input; The monitoring results (2a, 3a) include the measured temperatures (2a, 3a) and the temperatures (2a #, 3a #) determined by the machine learning model; method.

2. The method (100) of claim 1, wherein a structure produced by 3D printing is provided (111) as the three-dimensional mold (2).

3. The method (100) of claim 1, wherein said monitoring of said temperature comprises measuring (141) said temperature (2a, 3a) at multiple locations.

4. 3. The method (100) of claim 2, wherein said monitoring of said temperature comprises measuring (141) said temperature (2a, 3a) at multiple locations.

5. 4. The method (100) of claim 3, wherein at least one location on the exterior surface of the three-dimensional mold (2) where a local maximum or minimum of the temperature is expected based on the geometry of the mold is selected (141a) as a location for the temperature measurement.

6. 5. The method (100) of claim 4, wherein at least one location on the exterior surface of the three-dimensional mold (2) where a local maximum or minimum of the temperature is expected based on the geometry of the mold is selected (141a) as a location for the temperature measurement.

7. 7. The method (100) according to any one of claims 1 to 6, wherein when the three-dimensional mould (2) is provided, marking and / or preparation of the locations where it is intended to measure the temperature is carried out (112).

8. 7. The method (100) according to any one of claims 1 to 6, wherein when the three-dimensional mould (2) is provided, an access is left (113) for inserting a temperature sensor at a predetermined location in the interior space (21) of the mould (2).

9. The assessment of the quality (1a) of the object (1) is how the temperature (3a) of the filling material (3) was set (151) throughout the area designated for the polymerization; the extent to which the temperature (2a) of the three-dimensional mould (2) locally exceeds a predetermined maximum or falls below a predetermined minimum (152); With what temperature-time profile the object (1) is cooled (153), - how much the temperature of the filler material (3) and / or the three-dimensional mold (2) deviates from the model-based determined prediction (154); The method (100) of any one of claims 1 to 6, comprising determining:

10. The measures (4) for inducing the temperatures (2a, 3a) are Varying (161) the temperature of the oven in which the monomer is polymerized and / or the residence time of the object (1) in the oven; and / or Varying (162) the temperature at which the monomer is introduced into the interior space (21) of the three-dimensional mold, and / or - locally heating or cooling (163) said object (1); The method (100) of any one of claims 1 to 6, comprising:

11. 10. A computer program comprising machine-readable instructions that, when executed on one or more computers, cause the one or more computers and / or a manufacturing facility controlled by the one or more computers to perform the method (100) of any one of claims 1 to 6.

12. A machine-readable data carrier and / or download product containing a computer program according to claim 11.

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