Method for monitoring manufacturing process of 3D printer comprising magnetic levitation printing bed

Abstract

In various embodiments, a method for quality management of a printing process of a 3D object (402) comprising a plurality of layers (404, 406) is provided. The method includes a maglev printing bed (408) onto which a printing material is deposited to manufacture a 3D object, the method including determining a weight of the printing material that has been deposited to the printing bed until now as a function of a force acting on the maglev printing bed, and comparing the calculated weight with the measured weight in a continuous manner or at discrete time intervals. The method may be used to determine, based on the comparison, whether at least one portion of the layer of the printed 3D object meets an expected quality criterion.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of priority to European patent application serial number 23195423.1, filed on September 5, 2023, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0003] This invention relates to the field of additive manufacturing, and more particularly to a method for monitoring the manufacturing process of a 3D printer including a magnetically levitated printing bed. Background Technology

[0004] Additive manufacturing (AM), more commonly known as 3D printing, refers to a set of technologies that enable the creation of any kind of object or physical component by characteristically adding material layer by layer on a print bed (also known as a build platform). This process is fundamentally different from traditional machining, which involves subtracting material blocks through drilling, milling, and other methods.

[0005] 3D printers typically create 3D objects using additive manufacturing processes. First, a 3D model is designed using computer-aided design (CAD) software. Then, slicing software (a software engine) cuts the 3D model into multiple layers. Next, the object is built layer by layer by coordinating the movement of the printer's extrusion nozzles within the plane containing that layer (e.g., the x and y directions). Once a layer is complete, the extrusion nozzles (or the plane containing the completed layer) move vertically (e.g., in the z direction) to begin the extrusion process for the next layer. Printing material is continuously generated layer by layer until the object is completely built from bottom to top (from the 3D printer's perspective). The movement and three-dimensional movement of the extrusion nozzles, which determine the position of the printing material, are specified and controlled by a computer numerical control (CNC) programming language. Typically, in consumer and industrial 3D printers, G-code is used to achieve this.

[0006] It goes without saying that in order to obtain a 3D printed object with the required mechanical properties, each printing layer must be manufactured according to the design. That is, the outermost part of the layer and its infill pattern must be printed with high precision according to the design pattern. Based on the design pattern of the 3D object to be printed, the 3D printer software can determine how much printing material should be extruded in a given layer and in a given portion of that layer.

[0007] Variations in extruder nozzle output can lead to defects in printed 3D objects that may otherwise be undetectable. For example, if too much or too little material is extruded from a particular infill area compared to the actual design (corresponding to over-extrusion and under-extrusion, respectively), this variation may not be externally apparent when inspecting the final product. In cases of under-extrusion, the thickness or diameter of the extruded material is too small; in extreme cases, gaps between adjacent extruded portions may be visible when inspecting the layer. In cases of over-extrusion, the 3D printer extrudes more material than intended (e.g., according to software calculations). When over- or under-extruded portions are located on the outer shell of a layer, they can affect the size and appearance of the manufactured object.

[0008] Deviations in the amount of extruded material, especially in infill patterns, are undesirable because they can result in sections of greater or weaker mechanical strength within the 3D printed project, potentially altering its mechanical properties. Variations in the amount of extruded material can be caused by a variety of factors, such as incorrect nozzle height, incorrect printing temperature, and the presence of dust and dirt in the extrudate, which can lead to partial or complete nozzle blockage. For example, when the extruder temperature is too low, the printing material may not melt completely and may begin to adhere to the inner surface of the extruder nozzle. Considering that the inherent inaccuracy of thermostats can be as high as 10% in the worst case, it is clear that avoiding or at least reliably detecting over- and under-extrusion is a considerably challenging task, which is of great importance in 3D printing. The interaction between the magnetic fields of the mover and stator modules levitates the printing platform above the stator unit. By carefully controlling and varying the strength and direction of the magnetic fields, stable levitation and frictionless movement of the printing platform above the stator module can be achieved.

[0009] To achieve stability and precise control, the suspension mechanism is equipped with a sophisticated control system. This system utilizes magnetic field sensors (e.g., sensors strategically arranged across the structure) to monitor the platform's position and orientation. These sensors provide continuous feedback on the platform's position, enabling the control system to make real-time adjustments.

[0010] Based on feedback from magnetic field sensors (e.g., Hall effect sensors), the control system of the magnetic levitation system can regulate the current flowing through the coils in the stator module. By adjusting the strength and distribution of the magnetic field, the control system can counteract external disturbances that may cause changes in the position and / or orientation of the printing platform, thereby ensuring the stability and controllable movement of the printing platform throughout the manufacturing process.

[0011] Combined with the control system, the levitation mechanism provides the ability to precisely manipulate the printing platform along different directions and axes. By dynamically adjusting the magnetic field, the printing platform can move horizontally, move vertically to a lesser extent, or even rotate. Summary of the Invention

[0012] This invention provides a method for detecting defects, such as over- and under-extrusion, during a 3D printing process performed on an additive manufacturing machine with a levitated print bed. As described above, based on the design of the layers of a 3D object, the volume of printing material extruded in a given layer or a given portion thereof can be determined by the 3D printer software. The volume of a given layer or a portion thereof typically corresponds to the total volume of all its filaments (i.e., the curves and lines that make up the layer or its considered portion). Using the known extrusion nozzle diameter of the 3D printer and the density of the printing material used for printing, the weight of a given printed layer or a portion thereof can be calculated. According to the invention, during the manufacturing process, the weight of the 3D object being printed is determined by a 3D printer including a magnetically levitated print bed. The magnetic levitation system is configured to determine the weight of the printing platform on which printing material is deposited as needed by the magnetic force generated, which is used to hold the print bed, which is in a levitated state, above the stator of the magnetic levitation system. In this way, the weight of each layer and / or a portion of each layer can be compared with the theoretical weight obtained through calculation (the weight the printed 3D structure should have before the considered point in time during the manufacturing process). If there is a discrepancy between the measured weight and the calculated weight, the discrepancy indicates a manufacturing process defect, such as over-extrusion or under-extrusion, occurring during the 3D printing process. The extruded printing material can be, for example, any polymer suitable for 3D printing.

[0013] According to various embodiments, a method for monitoring the manufacturing process of a 3D printer is provided, wherein the 3D printer includes a suspended print bed onto which printing material is deposited to create a 3D object, the method comprising: determining parameters indicating forces acting on the suspended print bed to maintain its suspension; determining, based on the forces acting on the suspended print bed, the weight of the printing material deposited on the print bed to date; and comparing the determined weight of the printing material deposited on the print bed to date with a calculated weight of the printing material that should have been deposited on the print bed to date.

[0014] To achieve the objectives of this method, a 3D printer with a magnetically levitated print bed is used. The printing method of the 3D printer according to various embodiments corresponds to a common printing method known in the prior art, in which 3D objects are manufactured by printing one layer at a time. For example, by continuously measuring the weight of any portion of the printing material extruded onto the print platform, the weight of the corresponding portion of the printing material can be determined, and thus the weight of the 3D object can be determined and compared with a corresponding calculated value. As the printing process proceeds, the weight of the 3D object being manufactured on the print platform should gradually increase. The method according to the invention is configured to detect the deviation between the weight increase during the 3D printing process and the expected / predicted increase obtained from calculations. Therefore, the method according to various embodiments is able to directly detect, for example, over-extrusion and under-extrusion when they occur, which are respectively manifested as a decrease or increase in the measured weight of a portion of a layer compared to its corresponding calculated weight. It should be understood that the weight of the printing material extruded onto the print platform naturally includes the printing material already printed / extruded onto the print bed of the 3D printer. The 3D objects printed by 3D printers mentioned in this article can refer to any real-life object that can be manufactured by a 3D printer, such as 3D objects in architecture, toys, industrial design (automotive, aerospace, military, engineering, etc.), medical industry, biotechnology (e.g., human tissue replacement), fashion, food, and many other fields.

[0015] The weight of at least one portion of a layer can be calculated based on the path length and cross-section of the extruded printing material contained in that portion, as well as the density of the printing material. Its volume can be calculated from the path length and cross-section of the extruded printing material. The cross-sectional area of ​​the printing material can be determined by the diameter of the extruder nozzle used, while also considering other parameters, such as the travel speed of the extruder nozzle. The volume of the extruded material portion under consideration can be approximated, for example, as a cylinder or flattened cylinder extending along the path of the extruder nozzle. Once the volume of that portion of the layer is calculated, its theoretical weight can be calculated by multiplying that volume by the density of the printing material used. The printing temperature at which the printing material is extruded from the nozzle, or the printing material density at the temperature expected when the printing material begins to bond with the layer provided below (which can be approximated by the printing temperature), can be considered.

[0016] According to other embodiments of the method, the printing bed may be a magnetically levitated printing bed.

[0017] According to other embodiments of the method, the 3D printer may include an extruder that is movable independently of the levitation printing bed along a vertical axis perpendicular to the levitation printing bed.

[0018] According to other embodiments of the method, the levitation printing bed may include a permanent magnet and may be controlled by an electromagnetic field generated by a coil of a magnetic levitation platform.

[0019] According to other embodiments of the method, the weight of the printing material deposited onto the print bed so far can be calculated by dividing the force acting on the print bed by the acceleration due to gravity. For this purpose, the magnitude of the magnetic force required by the stator module of the magnetic levitation system to levitate the print bed at a predetermined distance above the surface of the stator module can be used as a reference value and compared with the magnitude of the magnetic force required by the stator module of the magnetic levitation system to levitate the print bed, including the printing material deposited thereon, at that distance above the surface. The excess weight of the print bed (i.e., the printing material) can be determined based on the surplus of the magnetic force required to keep a heavier print bed levitated.

[0020] According to other embodiments of the method, the weight of the printing material deposited on the print bed can be determined multiple times during the manufacturing process. Specifically, a weight value can be obtained at a time point corresponding to the start of 3D printing of a portion or the entire layer to be monitored. Another weight value can be obtained at another time point corresponding to the end of printing that portion or the entire layer to be monitored. Using this approach, the weight of any portion of the layer can be determined. Measurements of the weight of the printing material extruded or printed on the print bed can also be performed at predetermined time intervals or at predetermined time points (e.g., at the time when uniform, symmetrical, and / or particularly challenging portions have been printed).

[0021] According to other embodiments of the method, the weight of the printing material deposited on the print bed can be continuously determined during the manufacturing process. Therefore, the method according to this embodiment provides online or "live" monitoring of the printing process by continuously acquiring the weight value of the 3D object over time during printing. Precise quality management can be achieved by monitoring the weight evolution of the 3D object being printed and comparing it to a calculated weight evolution. Specifically, the method can pinpoint the deviation between the measured weight value and the calculated weight value to specific points and / or portions of the printed object. If errors repeatedly occur in (one or more) portions of the printed 3D object across various prints, the design of the 3D object can be evaluated and potentially optimized to obtain a design that is easier to manufacture and has a lower probability of error during its manufacturing. For the purposes of this invention, continuous measurement may include quasi-continuous measurement of the weight of the suspended print bed, at least several times per second, such as every 500 ms, every 250 ms, every 100 ms, or even more frequently. In fact, the sampling rate for obtaining weight measurements can be determined by the resolution of force measurements, and the weight value of the levitation printing bed is obtained through force measurements.

[0022] In summary, when continuously monitoring weight, pauses in the printing process (e.g., after completing one layer of a 3D object) will generate a plateau in the corresponding graph and are easily detected by the algorithm. Therefore, pauses after the manufacture of one layer can be used to generate markers in the corresponding weight-time graph, allowing the graphical portion of the weight-time graph to be easily assigned to its corresponding layer.

[0023] Furthermore, the range or path length of the deviation can be determined based on weight measurements. Based on this information, it can be determined whether the weight deviation will result in tolerable "defects" in the final 3D printed object. For example, defects in the form of overfill and / or underfill are tolerable when the density along the printing path and / or in specific regions within a layer is below a predetermined threshold.

[0024] According to other embodiments, when the deviation between the measured weight and the calculated weight of the printing material deposited on the print bed exceeds a first predetermined threshold for a predetermined number of times, at least one parameter of the printing process is adjusted.

[0025] Typically, the magnitude of the deviation between the measured weight and the calculated weight of a given portion (or the entire layer) of a layer provides information about the severity of under- or over-extrusion. For example, the variance of the measured weight can also be used as a quality parameter. A first predetermined threshold defines the maximum tolerable magnitude of over- or under-extrusion for the layer portion under consideration. For example, if under- or over-extrusion with a certain magnitude (e.g., 5% more than the expected / calculated weight) is detected in more than a certain number of layers of a 3D object and / or in more than a certain number of consecutive layers of a 3D object, at least one parameter of the 3D printer can be adjusted to counteract the over- or under-extrusion. The adjustment of at least one parameter can be performed in a closed-loop feedback loop, for example, via a PID controller. The adjustment of at least one parameter aims to identify optimal process parameters (nozzle height, printing temperature, extruder nozzle travel speed, etc.) to bring the printing process as close as possible to an optimal printing process free of over- and under-extrusion.

[0026] In other embodiments, if the 3D printing state cannot be brought into optimal parameters after a certain number of attempts to adjust the printing process parameters or after the printing process parameters have been adjusted for a certain period of time, the method may include terminating the 3D printing process.

[0027] According to other embodiments, the method may include halting the manufacturing process when the deviation between the measured weight and the calculated weight of the printing material deposited on the print bed exceeds a second predetermined threshold. The second predetermined threshold defines an extent (e.g., 10%) of over- or under-extrusion that is intolerable during the printing process and will lead to termination of the 3D printing process. For example, this termination criterion is useful when printing 3D objects for implantation in patients. This termination criterion prevents the printing of prosthetic parts that do not meet mechanical performance requirements and may be at risk of breakage due to weak points, necessitating further surgery to replace the broken prosthetic part. Similar to the first predetermined criterion, the second predetermined criterion may be combined with a frequency condition. That is, the 3D printing process may be terminated when the deviation between the calculated weight value and the measured weight value exceeds the second predetermined threshold more than a predetermined number of times or for a period longer than a predetermined threshold time period.

[0028] According to other embodiments of the method, the weight of the printing material deposited on the print bed can be obtained through a pre-obtained calibration curve that correlates a reference weight of the print bed (including a reference weight placed on the print bed) with a corresponding force acting on the suspended print bed. The force acting on the print bed can be primarily gravity, depending on the mass of the print bed. Assuming an equilibrium state exists that keeps the print bed suspended, the gravity acting on the print bed corresponds to a counter-magnetic force acting on the print bed to maintain its suspension.

[0029] A method for forming 3D objects using an additive manufacturing machine with a suspended printing bed, and a corresponding additive manufacturing machine generally used in the context of this invention, can be found in international application PCT / EP2022 / 083548. Attached Figure Description

[0030] Figure 1 An example design of a 3D object layer that can be used in the 3D printing process is shown.

[0031] Figure 2 A schematic diagram is shown illustrating the weight versus time relationship of the method according to the present invention, which can be used to monitor the 3D printing process.

[0032] Figure 3 An exemplary form according to the present invention can be used for quality management is shown.

[0033] Figure 4 A sketch of an exemplary 3D object on a suspended printing bed is shown.

[0034] Figure 5 The diagram illustrates different scenarios of weight evolution during 3D object printing.

[0035] Figure 6 An exemplary force versus weight graph is shown. Detailed Implementation

[0036] The following description of the embodiments is illustrative in nature and is not intended to limit the invention, its application, or its uses. Furthermore, the invention may be practiced according to the claims without some or all of this illustrative information.

[0037] Figure 1 A visual representation of an example design for layer 100 of a 3D object to be printed is shown. It can be seen that layer 100 is square and includes three outer shell layers 102, wherein the outermost shell describes a slice of the actual outer surface of the 3D object after printing. Layer 100 also includes a fill pattern 104 composed of mutually vertically arranged lines. The thickness of the lines depends on the diameter of the extruder nozzle used. Figure 1 In the diagram, the dashed rectangle represents an exemplary portion 106 of layer 100 to which the methods of various embodiments can be applied. That is, during printing, the weight of portion 106 can be determined by measuring or tracking the weight between the start and end points of the path of the extrusion nozzle corresponding to portion 106. It can be seen that the start and end points correspond to the points where the T-shaped portion 106 marked in the fill pattern 104 intersects the dashed rectangle. Generally, the exemplary portion 106 can include any part of layer 100 containing any fill pattern 104. Specifically, portion 106 can include the entire layer 100, i.e., its outer shell layer 102 and fill pattern 104.

[0038] exist Figure 2 The diagram illustrates an exemplary graph 200, where the x-axis 202 represents time in minutes and the y-axis 204 represents weight in grams. Within graph 200, a figure 206 is shown, depicting the recorded evolution of the weight of a 3D object printed on a suspended printing bed during its fabrication. Figure 206 can be viewed in essence as a continuous whole, with linearly increasing portions between platforms 208, highlighted with dashed circles (only every second platform is indicated by a reference numeral). Figure 206 depicts a scenario where the 3D printing process pauses after each layer of the 3D object is completed. During each pause, the weight of the 3D object ceases to increase, thus forming platforms 208, which can advantageously serve as markers demarcating subsequent layers from one another. Because the linearly increasing portions between platforms 208 have the same slope, Figure 206 indicates that the 3D printing process for each examined layer is performed at the same printing rate (the amount of printed material extruded per unit time). Furthermore, since the slope of each linear segment of pattern 206 is uniform, the printing process proceeds at a constant material output rate, indicating that there is no over- or under-filling (except in cases of overall offset of the entire pattern 206). The weight of each printed layer can be determined by comparing the weight corresponding to each platform 208. Comparing these weight values, obtained by directly measuring the 3D object during manufacturing, with calculated / expected theoretical values ​​provides reliable information about potential defects in the corresponding layers, most notably over- and under-filling. Pattern 206 is a continuous line, meaning it is generated by continuously monitoring the weight of the 3D object being printed on the printing platform over time. Here, the advantage of using a magnetic levitation system becomes apparent: it is able to continuously track the weight of the object being printed on a suspended printing bed. However, the method described herein can also be performed by sampling the weight of the printed 3D object at discrete points (e.g., at given time intervals). For slower 3D printing speeds, a longer weight sampling interval, such as 3 seconds, can be selected; while for faster 3D printing speeds, a shorter weight sampling interval, such as 1 second, can be selected.

[0039] If the measured weight value (e.g., the weight value corresponding to plateau 208 in graph 200) matches the theoretically predicted weight value, it can be inferred that each printed layer contains a predetermined amount of printing material. Therefore, the lines of printing material that make up the printed layer are very likely neither overfilled nor underfilled. Furthermore, the slope consistency of a given layer can be checked to verify this statement. If the weight value at any plateau does not match the theoretically predicted weight value, it can be inferred that too much or too little printing material has been deposited in the corresponding layer, and therefore, the layer is very likely affected by underfilling and / or overfilling. To further investigate suspected defect locations, graph 206 can be enlarged and compared with the weight evolution of the printed 3D object calculated on a finer timescale to better spatially locate points or regions within the layer where the measured weight curve begins to deviate from the calculated weight curve.

[0040] It is worth noting that if a layer is affected by over-extrusion and / or under-extrusion, the absolute weight at each subsequent platform 208 will differ from the calculated weight (due to the offset caused by over- or under-filling). In this case, the weight difference measured at platform 208 can be used to determine the actual platform weight measured by the weighing device.

[0041] Figure 3An exemplary implementation of the quality management scheme according to the present invention is shown. Table 300 has an exemplary format in which the comparison results between measured weight and calculated weight can be evaluated. It is worth noting that although the smallest unit of weight considered in Table 300 is a layer, the unit of weight considered can also be chosen to be smaller and involve portions of layers. Column 302 of Table 300 contains layer numbers, which are 1-10 in this example. Column 304 contains the actual weight, i.e., the measured weight of each inspected layer obtained by analyzing at least one operating parameter of the magnetic levitation system. Column 306 contains the planned weight, i.e., the expected weight obtained by calculating for each inspected layer. Column 308 lists the percentage of relative deviation between the measured weight and the calculated weight of each layer. In column 310, a classification of the determined deviations listed in column 308 is given, i.e., whether the determined deviations are acceptable. Each detected deviation is classified based on a comparison of its magnitude with a user-defined deviation acceptance threshold 316 (set to 2% in this example). Therefore, in the fifth column, each deviation with a magnitude greater than 2% is classified as unacceptable. Column 312 of Table 300 provides the most likely cause of the deviation. Here, based on the sign (+ or -) of the determined deviation, it can be determined whether the detected deviation is related to under-extrusion or over-extrusion. It should be understood that Table 300 only shows a simple example of how quality management can be implemented according to the methods disclosed herein.

[0042] The following describes a typical exemplary embodiment of the method according to the invention. While it is assumed that a single layer is considered, any other weighing unit, such as comprising multiple layers or a portion of a single layer, may also be considered. At the beginning of the method, the number of filaments contained in each layer of the 3D object can be calculated. This calculation can be performed by 3D printer software or dedicated software installed on a computer based on the layer architecture / layout. Based on the determined number of filaments, and further considering the diameter of the extruder nozzle, the volume of material to be deposited in each layer can be calculated. In the final calculation step, the expected weight of each layer can be determined based on the density of the material used to manufacture each layer. The actual printing process is performed so that the weight of the 3D object being printed can be determined during the printing process. This is achieved by a magnetically levitated printing bed configured such that the weight of the material extruded thereon can be determined. The weight can be recorded continuously during the printing process, or at predefined time intervals, such as every second, every two seconds, every three seconds, or every five seconds. Under normal circumstances, the weight of the 3D object recorded during printing should increase linearly with the continuous deposition of printing material (see [link to documentation]). Figure 2If the rate of weight gain decreases sharply or disappears during the printing process, this indicates that the extruder nozzles have stopped depositing material and can be interpreted as nozzle blockage. As mentioned above, after each layer of a 3D object is completed, it may be necessary to pause the 3D printer's extrusion for a predetermined amount of time. Since the weight does not change during these pauses, these pauses can be used as measurement points to attribute the (typically linear) portion of the weight versus time graph to the respective layers. Alternatively, the weight can be recorded during these periods of constant weight to determine the weight of the corresponding layer. Quality management can be performed based on a comparison of the measured weight with the predetermined / calculated weight. If the error is within a predefined threshold range, it is considered to have passed quality assurance. Otherwise, the user can be informed that the 3D printed object has been affected by under-extrusion or over-extrusion. If it is determined that under-extrusion or over-extrusion has occurred more than a certain number of times, and / or has existed for a total time period longer than the predetermined time, and / or has been detected in more than a certain number of layers, the flow rate of the printing polymer can be automatically adjusted by adjusting at least one parameter of the printing process to compensate for the flow rate deviation.

[0043] Figure 4 A sketch of an exemplary 3D object on a levitated printing bed is shown. In sketch 400, the 3D printed object 402 is situated on a magnetically levitated printing bed 408, which is suspended above the stator 10 of a magnetic levitation system. The 3D printed object 402 comprises multiple sequentially printed layers, starting with a first layer 406 and ending with a last layer 404, which will be extruded during the additive manufacturing process. In this example, each layer has the same weight, 2 grams. The combined weight of the 3D printed object 402 and the magnetically levitated printing bed 408 generates a force F. m This force is generated by the electromagnetic force F within the stator 410 of the magnetic levitation system. em This cancels out the distance between the magnetically levitated print bed 408 and the stator 410, keeping it constant throughout the printing process. In other words, the control loop within the magnetic levitation system attempts to maintain a balanced state in which the electromagnetic force F acting on the levitated print bed 408 is neutralized. em The force F acting on the printing bed, including the 3D printed object m The forces are equal. This balance of forces keeps the levitation printing bed 10 at a constant distance above the surface of the stator 410. Since the weight of the levitation printing bed 408 is known and constant, the weight of the 3D printed object 402 can be determined in this way at any point during the manufacturing process. Because the levitation printing bed 408 moves frictionlessly above the surface of the stator 410, the forces acting on the levitation printing bed 408 (including the 3D printed object 402) are equal to the force of gravity.

[0044] Figure 5An exemplary evolution of the weight of a 3D-printed object is shown, from which various types of error can be derived. Graph 500 illustrates the possible weight evolution of several 3D-printed objects consisting of multiple layers, where the x-axis represents the layer number and the y-axis represents the determined weight. The first weight curve 502 represents the ideal weight distribution of the 3D object being printed, where the weight increases by 2 grams with each printed layer. The permissible deviation from the ideal weight is represented by the gray shaded area around the first weight curve 502. The second weight curve 504 represents a printing process where the third layer is affected by overflow, resulting in a weight increment of more than 2 grams for the fourth layer. The third weight curve 506 represents a printing process affected by underflow, resulting in a weight increment of less than 2 grams for the fourth layer. The fourth weight curve 508 represents a printing process affected by the 3D-printed object detaching from and being lost from the suspended print bed, causing the measured weight to drop to zero. It can also be seen that the loss event occurs after the fifth layer has been completed. If the weight deviation of a 3D object exceeds a predefined threshold and / or occurs more than a predefined number of times, the printing process will be terminated, which is represented as termination event 510 in graphic 500.

[0045] In this system, the x-axis represents force of any unit and the y-axis represents weight. Figure 6 In graph 600, a force-weight calibration curve 602 is shown. This curve 602 can be obtained during calibration prior to the actual 3D printing process by placing a reference weight on the print bed and determining the corresponding force acting on the levitated print bed. Calibration curve 602 can correspond to extrapolation of individual sampling data points. Calibration curve 602 can be used during the 3D printing process to measure the electromagnetic force F generated within the stator 410 of the magnetic levitation system. em This is converted to the weight of the suspended printing bed on which the 3D printed object is mounted.

Claims

1. A method for monitoring the manufacturing process of a 3D printer, wherein, The 3D printer includes a suspended printing bed, onto which printing material is deposited to create a 3D object, the method comprising: Determine the parameters of the forces acting on the suspended printing bed to maintain its suspension; The weight of the printing material deposited onto the printing bed so far is determined based on the force acting on the suspended printing bed; The determined weight of the printing material that has been deposited onto the print bed so far is compared with the calculated weight of the printing material that should have been deposited onto the print bed so far.

2. The method according to claim 1, wherein, The printing bed is a magnetic levitation printing bed.

3. The method according to claim 1 or 2, wherein, The 3D printer includes an extruder that is movable independently of the suspended printing bed along a vertical axis perpendicular to the suspended printing bed.

4. The method according to any one of claims 1 to 3, wherein, The levitation printing bed includes a permanent magnet and is controlled by an electromagnetic field generated by a coil of a magnetic levitation platform.

5. The method according to any one of claims 1 to 4, wherein, The weight of the printing material deposited onto the printing bed so far is calculated by dividing the force acting on the printing bed by the gravitational acceleration.

6. The method according to any one of claims 1 to 5, wherein, The weight of the printing material deposited on the printing bed is determined multiple times during the manufacturing process.

7. The method according to any one of claims 1 to 6, wherein, The weight of the printing material deposited on the printing bed is continuously determined during the manufacturing process.

8. The method according to any one of claims 1 to 8, further comprising: When the deviation between the measured weight and the calculated weight of the printing material deposited on the print bed exceeds a first predetermined threshold, at least one parameter of the printing process is adjusted.

9. The method according to claim 8, wherein, When the deviation between the measured weight and the calculated weight of the printing material deposited on the print bed exceeds a first predetermined threshold number of times, at least one parameter of the printing process is adjusted.

10. The method according to any one of claims 1 to 9, further comprising: The manufacturing process is terminated when the deviation between the measured weight and the calculated weight of the printing material deposited on the printing bed exceeds a second predetermined threshold.

11. The method according to any one of claims 1 to 10, wherein, The weight of the printing material deposited on the printing bed is obtained through a pre-obtained calibration curve that correlates the reference weight with the corresponding force acting on the suspended printing bed.

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