Control method of 3D printer for construction

Abstract

The invention relates to a control method of a 3D printer for construction for printing and forming various structures, the 3D printer is composed of a controller (10), a scanner (30) and a computer (40), the controller (10) controls the 3D printer for construction, the scanner (30) detects three-dimensional surface information, the computer (40) is connected with the controller (10) and the scanner (30), and the scanner (30) is connected with the computer (40). A scanner (30) detects measured surface information (39) of a printing material (20) and sends it to a computer (40), which calculates a printing error by comparing the measured surface information (39) with planned surface information (49), and then modifies command information (19) to compensate for the printing error and sends it to a controller (10). According to the invention, when the 3D printer for construction is used for forming a structure, not only can the error of the printing material (20) be quickly recognized in real time, but also the set value of the controller (10) of the 3D printer for construction can be immediately adjusted according to the recognized error.

Description

Technical Field

[0001] The present invention relates to a control method for a construction 3D printer for printing and forming various structures, which is composed of a controller 10, a scanner 30 and a computer 40, wherein the controller 10 controls the construction 3D printer, the scanner 30 detects three-dimensional surface information, the computer 40 is connected to the controller 10 and the scanner 30, the scanner 30 detects the measured surface information 39 of the printing material 20 and sends it to the computer 40, the computer 40 calculates the printing error by comparing the measured surface information 39 with the planned surface information 49, and then modifies the command information 19 to compensate for the printing error and sends it to the controller 10. Background Art

[0002] A 3D printer for construction is a device that uses linear extrusion and stacking of fluidized bed materials such as concrete or mortar to complete a structure of a desired shape. It can not only omit or minimize the mold building process that is essential in the construction of traditional concrete structures, but also achieve significant advantages in terms of formability and construction period. Relevant prior arts include Patent No. 2396629, etc.

[0003] As shown in FIG. 1 , conventional construction 3D printers, including Patent No. 2,396,629, extrude fluidized bed printing material 20, such as concrete or mortar, in a linear shape through a movable nozzle 11. The extruded linear printing material 20 is stacked and hardened to complete the structure, and the figure shows the situation of printing a wall.

[0004] The printing material 20 of these construction 3D printers basically has the form of linear extrudates, and the linear extrudates are stacked along the moving path of the nozzle 11 to form a planned structure. In the 3D printer shown in Figure 1, the nozzle 11 that spits out the printing material 20 is set in the printer body in the form of a gantry crane, so that it can move freely horizontally and vertically. In addition, various cranes such as jib cranes, multi-joint industrial robots, etc. can also be used to freely move the nozzle 11 and control its movement. Summary of the invention

[0005] Technical issues

[0006] As described above, the printing material 20 of the construction 3D printer can basically be said to be a fluidized bed linear extrudate, and as shown in the enlarged portion of Figure 1, these fluidized bed materials, i.e., printing materials 20 of concrete or mortar, etc., are formed by stacking new linear printing materials 20 of the fluidized bed ejected from the nozzle 11 on top of the initial base or the printed printing layer of the lower layer.

[0007] Therefore, during the printing process of the construction 3D printer, as new printing materials 20 are repeatedly stacked on top of the printed printing layers on the upper or lower part of the initial base, the upper end elevation of the entire printing material 20 stack increases and the planned structure is formed. At this time, due to errors in the moving bed such as the position and speed of the nozzle 11 that extrude the new printing material 20, external factors such as wind load or vibration, or excessive or insufficient physical properties such as viscosity and fluidity of the fluidized bed printing material 20, printing errors may occur in which the position or shape of the printing material 20 is different from the plan.

[0008] FIG2 illustrates the printing error of the above-mentioned construction 3D printer, showing a cross section of the printing material 20 cut on a vertical plane perpendicular to the direction of the nozzle 11. The solid line in the figure represents the actual printed shape of the printing material 20, and the dotted line in the figure represents the originally planned shape.

[0009] The printing errors of these construction 3D printers can be divided into offset errors and height errors, wherein the offset error refers to the deviation of the overall position of the center line of the printing material 20 from the planned position, and the height error refers to the height of the upper end of the printing material 20 being higher or lower than the return height. These offset errors and height errors can be formed individually or by a combination of heterogeneous errors.

[0010] In Figure 2 showing the printing errors of a construction 3D printer, the displacement error is displayed in the upper part of the figure, and the height error is displayed in the lower part of the figure. The upper left and upper right sides of the figure respectively show the displacement error of the printing material 20 shifting to the left relative to the planned position and the displacement error of the printing material 20 shifting to the right relative to the planned position. The lower left and lower right sides of the figure respectively show the height error of the upper end height of the printing material 20 being lower than the planned height and the height error of the upper end height of the printing material 20 being higher than the planned height.

[0011] The causes of the misalignment error shown in the upper part of FIG. 2 include errors in the movement of the position and speed of the 3D printer nozzle 11 and external influences such as wind loads or vibrations. In particular, when the nozzle 11 rotates along a curve on a plane, the ejected printing material 20 deviates to the outside of the rotation direction due to centrifugal force, which may cause misalignment errors.

[0012] When these offset errors occur, as shown in the upper part of FIG. 2 , the center line of the offset error 20 is spaced apart from the planned center line, and the outer contour lines on both sides of the printing material 20 are also spaced apart from the planned outer contour lines in the same direction.

[0013] The causes of the height error shown in the lower part of FIG. 2 include inappropriate properties of the material ejected from the nozzle 11. If the slump value of the concrete ejected from the nozzle 11 is too large, that is, the concrete mixture is thinner, the upper end height of the printed material 20 is lower than the planned height. If the slump value of the concrete is too small, that is, the concrete mixture is thicker, the upper end height of the printed material 20 exceeds the planned height.

[0014] In addition, as shown in the lower part of FIG. 2 , for the height error caused by the physical properties of the concrete, the side contour of the printed material 20 is also accompanied by an error. For the excessively large slump concrete shown in the lower left side of FIG. 2 , the upper end height of the printed material 20 is excessively reduced, and at the same time, the outer contours on both sides of the printed material 20 collapse outward, thereby forming an outer contour line that protrudes outward compared to the planned outer contour line. For the excessively small slump concrete shown in the lower right side of FIG. 2 , the lateral expansion of the cross-section caused by the deadweight of the printed material 20 is suppressed immediately after printing, so that the upper end height of the printed material 20 is formed on the upper side of the planned height, and the outer contours on both sides are also formed to shrink toward the center side.

[0015] In addition, although not shown in Figure 2, height errors may occur even when the moving speed or discharge flow rate of the nozzle 11 is not appropriate. When the moving speed of the nozzle 11 is too fast or the discharge flow rate is insufficient, the upper end height of the printed material 20 may drop due to insufficient printing volume per unit area or per unit interval. When the moving speed of the nozzle 11 is too slow or the discharge flow rate is too large, the upper end height of the printed material 20 may rise due to excessive printing volume per unit area or per unit interval. When height errors occur due to the moving speed or discharge flow rate of these nozzles 11, depending on the situation, they may not be accompanied by errors in the outer contour of the printed material 20.

[0016] In this way, in existing construction 3D printers, various reasons will lead to various types of errors. As mentioned above, since the construction 3D printer has the operating characteristics of forming a planned structure by stacking multiple layers of linear printing material 20, the errors in each layer of the printing material 20 may accumulate during the sequential stacking and forming process of the entire stack, which will cause serious damage to the construction accuracy and performance of the entire structure.

[0017] Therefore, when using a traditional construction 3D printer to print structures, it is necessary to continuously detect the offset error and height error in the printing material 20. If the detection result exceeds the tolerance, the 3D printer can only stop running, adjust the control setting value of the 3D printer, and then resume operation.

[0018] In particular, error detection and control set value adjustment in traditional construction 3D printers are based on manual operation by workers, which requires long-term operation by highly skilled technicians. Error detection and set value adjustment can only be repeated through trial and error, which inevitably leads to problems such as reduced work efficiency and construction delays.

[0019] Technical Solution

[0020] The present invention is proposed in consideration of the above-mentioned problems. A control method for a construction 3D printer is characterized in that it is composed of a construction 3D printer, a controller 10, a scanner 30 and a computer 40, wherein the construction 3D printer prints a printing material 20 from a moving nozzle 11, the controller 10 controls the construction 3D printer, the scanner 30 detects the surface information of the subject, the computer 40 is connected to the controller 10 to send command information 19 to the controller 10, and is connected to the scanner 30 to receive and process the surface information sent by the scanner 30, and the control method The method comprises: a measuring step (S10), in which a scanner 30 detects measured surface information 39 of a printing material 20 printed by a construction 3D printer and sends it to a computer 40; a comparing step (S20), in which the computer 40 calculates a printing error by comparing the measured surface information 39 of the sent printing material 20 with the planned surface information 49 of the planned structure; a modifying step (S31), in which if the printing error exceeds the tolerance, the computer 40 modifies the command information 19 to compensate for the printing error; and a commanding step (S32), in which the computer 40 sends the modified command information 19 to the controller 10.

[0021] In addition, the control method of the construction 3D printer of the present invention is characterized in that, in the comparison step (S20), the STL file constituting the planned surface information 49 and the STL file constituting the measured surface information 39 are overlapped, and if the information in the overlapping STL files shows a difference value exceeding the standard value, it is regarded as a printing error.

[0022] Beneficial Effects

[0023] Through the present invention, when a construction 3D printer is used to form a structure, not only can the error of the printing material 20 be quickly identified in real time, but the setting value of the controller 10 of the construction 3D printer can also be immediately adjusted according to the identified error.

[0024] In particular, the real-time detection of the printing material 20 error and the adjustment of the controller 10 can be automatically performed by a computer without detailed user operation, and can quickly respond to the early stage of the occurrence of the printing material 20 error, thereby preventing the continuous occurrence and accumulation of the printing material 20 error and improving the accuracy of structural construction using a construction 3D printer.

[0025] In addition, since the error detection of the printing material 20 and the setting value adjustment of the construction 3D printer controller 10 are performed without stopping the operation of the 3D printer, it is possible to ensure work efficiency and shorten the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a schematic diagram of an existing construction 3D printer.

[0027] FIG. 2 is an explanatory diagram of printing material errors of a construction 3D printer.

[0028] FIG. 3 is a block diagram of a system for implementing the present invention.

[0029] FIG. 4 is a diagram for explaining the scanner operation method of the present invention.

[0030] FIG. 5 is an explanatory diagram of the design model information processing method of the computer of the present invention.

[0031] FIG. 6 is a schematic diagram of a construction 3D printer for implementing the present invention.

[0032] FIG. 7 is a schematic diagram of a construction 3D printer equipped with a scanner for implementing the present invention.

[0033] FIG. 8 is a schematic diagram of a nozzle of a construction 3D printer equipped with a scanner for implementing the present invention.

[0034] FIG. 9 is a flow chart of the present invention.

[0035] FIG. 10 is a diagram for explaining a method of comparing measured surface information with planned surface information.

[0036] FIG. 11 is a schematic diagram showing a comparison state between measured surface information and planned surface information of a construction 3D printer according to the present invention. DETAILED DESCRIPTION

[0037] The specific configuration and implementation process of the present invention are described below with reference to the accompanying drawings.

[0038] First, Figure 3 shows the various components of the system for implementing the present invention and their connection relationships. The present invention is implemented by a construction 3D printer, a controller 10, a scanner 30 and a computer 40, wherein the construction 3D printer prints a printing material 20 from a moving nozzle 11, the controller 10 controls the construction 3D printer, the scanner 30 detects surface information of the subject, and the computer 40 is connected to the controller 10 to send command information 19 to the controller 10, and is connected to the scanner 30 to receive and process the surface information sent by the scanner 30.

[0039] In the present invention, the controller 10 is a device responsible for controlling the overall operation of the 3D printer, including the movement of the nozzle 11. It is connected to multiple motors installed on the 3D printer for moving the nozzle 11. According to the instructions of the computer 40, that is, the input of command information 19 such as G-code, the controller 10 controls the moving position and moving speed of the nozzle 11.

[0040] In addition, for a construction 3D printer that can control the ejection speed of the printing material 20 of the nozzle 11, this can also be controlled by the controller 10. Although not shown in the figure, for a construction 3D printer that can adjust the ratio of the fluidized bed material supplied to the nozzle 11, the ratio can also be adjusted by the controller 10.

[0041] The scanner 30 of the present invention is a device for detecting surface information of the external shape of a specified subject or object. The specific detection technology of each model may be different, but it performs the function of generating surface information, which digitizes the information of the surface shape of the subject or object. This surface information may include an STL (STereo Lithography) file that approximates the surface of the subject or object as a continuous triangular network.

[0042] That is, as shown in Figure 4, the scanner 30 of the present invention is a device that measures the surface shape of the printed material 20 as a test object or an object and generates surface information in the STL file format. As a specific method, various methods can be applied, including multi-distance measuring devices such as laser point 3D scanners, shape information detection devices such as 3D scanners using optical triangulation methods, shooting devices using photogrammetry technology, or 3D model generation devices using post image processing technology.

[0043] In this way, various methods can be applied in the operation of the scanner 30 of the present invention, but in summary, the main function of the scanner 30 of the present invention can be said to be to generate STL file format information that can specify the surface shape of the printed material 20 as a specimen or an object. As shown in Figure 4, it can be said that the STL file, that is, the surface information, is generated by scanning the printed material 20 printed by the construction 3D printer, and the STL file is the numerical information of the triangular network structure as shown in the lower part of the figure.

[0044] The function of these surface information is not limited to the simple designation of the external shape, but also specifies the spatial coordinates of the surface information generated by specifying the position of the scanner 30 in advance, which is important as information that can be used to perform the comparison step ( S20 ) described later.

[0045] That is, the scanner 30 of the present invention has its own built-in control computing device and storage device, which converts the measurement value into the above-mentioned surface information and stores it. The computer 40 is connected to the scanner 30 via wired or wireless means, and the surface information generated by the scanner 30 is input into the computer 40.

[0046] On the other hand, the computer 40 of the present invention is connected to the scanner 30 and the controller 10 by wire or wirelessly to receive and process surface information, and generate and send command information 19, all of which are processed by a dedicated program installed on the computer 40.

[0047] FIG5 shows the processing process of the computer 40 of the present invention on the design model information 48, which is information for quantifying the design information such as the shape and specification of the structure to be constructed. The design model information 48 is processed by the computer and converted into planning surface information 49 such as STL files, and the planning surface information 49 is further converted into command information 19 such as G-code.

[0048] The computer 40 converts the design model information 48 into command information 19 such as G code, which is used to input into the controller 10 of the construction 3D printer. The controller 10 controls the movement of the 3D printer nozzle 11 according to the input of the command information 19. As shown in the upper part of Figure 5, the printing material 20 is printed with the shape consistent with the design model information 48 as the target.

[0049] In the embodiment shown in Figure 5, when converting the design model information 48 into the command information 19, the process of directly converting the design model information 48 into the command information 19 is not adopted, but the process of first converting the design model information 48 into the planning surface information 49 and then converting it into the command information 19 again is adopted, that is, the design model information 49 of the designed 3D model, etc. is first converted into an STL file, and then the STL file is converted into G code again. Most 3D printers including construction 3D printers use G code as the standard command information 19, and the G code is created based on the STL file. Since many conversion programs for creating G code based on STL files are commonly used, it is assumed here that they are used.

[0050] Of course, the above-mentioned special program installed on the computer 40 and responsible for processing the information required in the entire process of executing the present invention can directly convert the design model information 48 into command information 19 through its own processing function, and can also improve the efficiency and compatibility of system construction by using the general G-code conversion program in the form of a subroutine or program module.

[0051] Figure 6 shows a construction 3D printer in the state of implementing the present invention. As shown in the figure, the scanner for obtaining the surface information of the printing material 20 printed by the nozzle 11 is operated in a fixed position during the implementation of the present invention. As shown in the figure, multiple scanners 30 are installed in different positions and are configured to be able to measure the parts of the printing material 20 hidden by the existing printing structure or the construction 3D printer itself.

[0052] In the embodiment shown in FIG6 , although two scanners 30 are used, a single scanner 30 may be used for a simple printed material 20 that does not form the aforementioned hidden portion, and more than two scanners 30 may be used in cases where hidden portions are often formed, such as complex printed materials 20 or printed materials 20 combined with existing structures.

[0053] As described above, the function of the surface information generated by the scanner 30 and provided to the computer 40 is not limited to the simple designation of an external shape, and the spatial coordinates of the surface information generated by pre-specifying the position of the scanner 30 are also specified, and the surface information generated by multiple scanners 30 can be processed like the surface information generated by a single scanner 30, simply by applying the same coordinate system to overlap them.

[0054] As a specific method for converting a plurality of surface information generated by a plurality of scanners 30 into a single surface information by overlapping them, a method such as averaging the values ​​of repeated detection parts or assigning a weight value to a close-range measurement value may be applied. Since a person skilled in the art can select and implement such a method for overlapping a plurality of surface information, there is no specific limitation on the scope of the claims.

[0055] On the other hand, FIG. 7 and FIG. 8 show an embodiment in which a scanner 30 is installed on a construction 3D printer. FIG. 7 shows a plurality of scanners 30 installed on a structural frame of a 3D printer, and FIG. 8 shows a plurality of scanners 30 installed on a nozzle 11.

[0056] In this way, the advantage of installing the scanner 30 on the 3D printer is that it can not only minimize the hidden parts that may be formed by the printing material 20 or the 3D printer itself, but also omit the initial setting work for specifying the spatial coordinates of the surface information generated by the scanner 30.

[0057] Of course, in the embodiments of Figures 7 and 8, during the operation of the construction 3D printer, the installed scanner 30 moves together, and the spatial coordinate reference point of the surface information can move at any time, but since the movement of the installed scanner 30 accompanying the operation of the 3D printer is performed in a state where its path is accurately determined, the reference point can be accurately and quickly identified by inversely calculating the movement path, as shown in Figure 6, so that the same surface information as the scanner 30 that always operates in a fixed state can be detected.

[0058] The present invention implemented by such a configuration, as shown in FIG. 9 , starts from a measuring step ( S10 ) in which the scanner 30 detects measured surface information 39 of the printing material 20 printed by the construction 3D printer and sends it to the computer 40 .

[0059] As shown in FIG. 4 , the measuring step ( S10 ) is a process of establishing measured surface information by detecting the surface information of the printing material 20 printed by the nozzle 11 in real time. As described above, the measured surface information 39 is generated in a format such as an STL file and sent to a computer 40 connected to the scanner 30 by wire or wirelessly.

[0060] Then, a comparison step (S20) is performed, that is, the computer 40 calculates the printing error by comparing the measured surface information 39 of the sent printing material 20 with the planned surface information 49 of the planned structure. The comparison process of the measured surface information 39 and the planned surface information 49 is shown in Figures 10 and 11.

[0061] First, FIG. 10 shows a situation where it is assumed that only the measured surface information 39 and the planned surface information 49 are compared with each other and no action is taken thereafter. As shown in the figure, it can be confirmed that a displacement error is occurring in which the printing material 20 is offset to the right based on the direction in which the nozzle 11 moves on the plane, and as the right-side displacement error accumulates, the printing material 20 is excessively offset, resulting in serious molding defects.

[0062] FIG11 shows a situation in which the printed material 20 is modified by applying the present invention when an error occurs due to the same external factors as in FIG10 . It can be confirmed that at the beginning of the error on the right side, the command information 19 is modified immediately after the corresponding printing error exceeds the tolerance, and accordingly, the deviation error is gradually modified to detect the measured surface information 39 that is as close as possible to the planned surface information 49.

[0063] Of course, it can be seen from Figure 11 that even in the construction 3D printer applying the present invention, it is impossible to completely prevent the occurrence of printing errors due to various external factors, but once the printing error exceeds the tolerance, even if the printing error that has occurred still exists, the printing error that occurs in the future can be greatly reduced by immediately modifying the command information 19, thereby preventing serious defects and functional losses in the printed material 20 due to the accumulation of printing errors.

[0064] In the comparison step (S20), as a specific comparison method between the planned surface information 49 and the measured surface information 39, as shown in Figures 10 and 11, the following method may be included, that is, by applying the same coordinate system and the same scale, the STL file constituting the planned surface information 49 and the STL file constituting the measured surface information 39 are overlapped. If the triangular network information in the overlapping STL files on both sides has a difference value exceeding a preset standard value, it is regarded as a printing error.

[0065] In particular, when printing errors are detected by overlapping the triangular networks of these two-side STL files, the overall construction of the planned surface information 49 and the measured surface information 39, that is, the overall shape comparison between the planned shape of the printing material 20 and the shape of the actually printed printing material 20, rather than local comparison, can be performed, so that each detailed printing error type can be accurately identified.

[0066] In other words, by comparing the overall shape of the planned surface information 49 and the measured surface information 39 executed in the comparison step (S20), when the above-mentioned misalignment error occurs, it is not simply to calculate whether the error exists and the value, but to accurately judge, for example, whether the cross-sectional shape of the printed material 20 is offset as a whole, resulting in an error in the movement of the center line itself, or whether a specific part of the printed material 20 is concave due to poor material properties or an incorrect extrusion speed, etc., causing a misalignment error, and take appropriate measures in subsequent steps.

[0067] The printing error compensation process in the modification step (S31) can ultimately be said to be a process in the opposite direction or reverse effect of the induced printing error. For example, when a right-side error occurs, the movement path of the nozzle 11 in the command information 19 is offset to the left, and when a left-side error occurs, the movement path of the nozzle 11 in the command information 19 is offset to the right.

[0068] In addition, when a height error occurs due to insufficient upper end height, the moving speed of the nozzle 11 is reduced to increase the discharge amount of the printing material 20 per unit interval, or the ratio is adjusted to reduce the slump value. When a height error occurs due to excessive upper end height, the moving speed of the nozzle 11 is increased to reduce the discharge amount of the printing material 20 per unit interval, or the ratio is adjusted to increase the slump value. As described above, for a construction 3D printer that can adjust the ratio of the fluidized bed material supplied to the nozzle 11, the adjustment of the ratio can also be controlled by the controller 10, so that the adjustment of the slump value can also be performed by modifying the command information 19 for the controller 10.

[0069] This modification of the command information 19 and compensation of the printing error can be performed without accurately identifying the cause of the printing error. This can be achieved by repeatedly executing the acquisition of the measured surface information 39 and the modification of the command information 19 that are unique to the present invention. As can be seen from Figure 11, if the movement path of the nozzle 11 in the command information 19 is modified to shift to the left to compensate for the right-side deviation error, the left-side deviation error is caused due to the excessive leftward movement of the nozzle 11, and the command information 19 is immediately modified to the right to compensate for this error. In this repeated modification process, the deviation error gradually decreases, and the movement path of the nozzle 11 in the command information 19 converges to the correct position.

[0070] In this way, when the command information 19 is modified through the modification step (S31), the execution computer 40 sends the modified command information 19 to the controller 10 in the command step (S32), as shown in FIG. 11, a printed material 20 having a shape close to the planned surface information 49 can be formed.

[0071] Description of Reference Numerals

[0072] 10: Controller 11: Nozzle

[0073] 19: Command information 20: Print material

[0074] 30: Scanner 39: Measured surface information

[0075] 40: Computer 48: Design model information

[0076] 49: Planning surface information S10: Measurement steps

[0077] S20: Comparison step S31: Modification step

[0078] S32: Command step.

Claims

1. A control method for a construction 3D printer, characterized in that: The invention is composed of a construction 3D printer, a controller (10), a scanner (30) and a computer (40), wherein the construction 3D printer linearly extrude and print fluidized bed printing material (20) from a moving nozzle (11), the controller (10) controls the construction 3D printer, the scanner (30) detects surface information of a subject including spatial coordinates, and the computer (40) is connected to the controller (10) to send command information (19) to the controller (10), and is connected to the scanner (30) to receive and process the surface information sent by the scanner (30). The control method comprises: a measuring step (S10), wherein the scanner (30) detects measured surface information (39) of a printing material (20) printed by the construction 3D printer and sends it to the computer (40), wherein the position of the scanner (30) is pre-specified to generate spatial coordinates, and the measured surface information (39) includes spatial coordinates; A comparison step (S20), wherein the computer (40) calculates a printing error by comparing the measured surface information (39) of the sent printing material (20) with the planned surface information (49) of the planned structure; a modification step (S31), if the printing error exceeds the tolerance, the computer (40) modifies the command information (19) to compensate for the printing error, deflects the moving path of the nozzle (11) in the command information (19), or increases or decreases the moving speed of the nozzle (11) in the command information (19); and In a command step (S32), the computer (40) sends the modified command information (19) to the controller (10).

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