System and method for monitoring the density of a printed structure during a 3D printing process

Abstract

The monitoring system and method for printing structure density in the 3D printing process of the present application, the monitoring system comprises a weighing device, a three-dimensional scanner, and a computer connected with both, the weighing device measures the mass of the printing structure, the three-dimensional scanner measures the volume of the printing structure, and the computer calculates the relative density of the printing structure. The monitoring method is as follows: printing the first layer structure L1 and measuring its mass and volume, calculating the relative density I1 of L1, judging whether I1 is within the allowable value range, printing the second layer structure L2 on L1, measuring the mass and volume of the first and second layer structures L1 and L2 respectively, calculating the relative density I2 of L1 and L2, judging whether I2 is within the allowable value range, and repeating the above steps to print layer by layer on the second layer structure L2 to the Nth layer structure L N , measuring the mass and volume of L1 to L N , and calculating the relative density I N of the first layer structure L1 to the Nth layer structure L N , respectively, such as I N , if it is within the allowable value range, the printing structure meets the construction requirements.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a system and method for monitoring the density of printed structures during the 3D printing process. Background Technology

[0002] During the 3D printing process of components, the actual density of the printed structure inevitably deviates from the design density. If the difference is large, it will directly affect the strength and safety of the printed structure. Therefore, it is very important to monitor the density of the printed structure during the printing process.

[0003] Because 3D printing is a complex dynamic forming process, the weight of the later-printed layers can cause deformation of the already printed layers. However, there is currently a lack of effective methods for monitoring the density of the printed structure. To ensure the safety of the 3D printing process, as well as the strength and quality of the printed structure, it is necessary to develop a device and method for monitoring the density of the printed structure during the 3D printing process. Summary of the Invention

[0004] To address the current lack of monitoring equipment and methods for the density of printed structures during the 3D printing process, the purpose of this invention is to provide a system and method for monitoring the density of printed structures during the 3D printing process.

[0005] The technical solution adopted by this invention to solve its technical problem is: a monitoring system for the density of a printed structure during 3D printing, comprising a weighing device, a 3D scanner, and a computer connected to both. The weighing device is used to measure the mass of the printed structure, the 3D scanner is used to measure the volume of the printed structure, and the computer is used to calculate the relative density of the printed structure based on the acquired data. The weighing device is located below the printed structure and includes a support platform, weighing sensors, an automatic leveling base, and a data acquisition device. The support platform supports the printed structure, and at least three weighing sensors are evenly distributed at the bottom of the support platform. The data acquisition device is connected to the signals of at least three weighing sensors, and the data acquisition device, the automatic leveling base, and the 3D scanner are all connected to the computer.

[0006] The 3D printing process monitoring system for the density of printed structures of the present invention includes a weighing device, a 3D scanner, and a computer. The platform of the weighing device supports the printed structure, and at least three weighing sensors are evenly distributed on the bottom of the platform to measure the mass of the printed structure. The weighing device measures the mass of the currently formed printed structure, the 3D scanner measures the volume of the currently formed printed structure, and the computer calculates the relative density of the currently formed printed structure based on the mass and volume data, and determines whether the strength and mass of the printed structure meet the construction requirements. During the 3D printing process of components, this monitoring device can measure the mass and volume of the printed structure layer by layer in real time and quantitatively. By calculating the relative density of the printed structure as a basis for judging its strength and mass, it is beneficial to the quality control and safe construction of 3D printing.

[0007] Furthermore, each weighing sensor of the weighing device is connected to an automatic leveling base at its bottom.

[0008] Furthermore, the platform of the weighing device is made of transparent glass.

[0009] In addition, the present invention also provides a method for monitoring the density of printed structures during the 3D printing process, the steps of which are as follows:

[0010] S1: Print the first layer structure L1 on the platform of the weighing device. The weighing sensor measures the mass of the first layer structure L1 after it is formed as m1. The 3D scanner scans and measures the volume of the first layer structure L1 after it is formed as V1. Calculate the relative density I1 of the first layer structure L1.

[0011] S2: When the relative density I1 of the first layer structure L1 after molding is calculated in step S1 and meets the construction requirements, the second layer structure L2 is printed on the first layer structure L1. The weighing sensor measures the mass of the first layer structure L1 and the second layer structure L2 after molding as m2. The three-dimensional scanner scans and measures the volume of the first layer structure L1 and the second layer structure L2 after molding as V2. The relative density I2 of the first layer structure L1 and the second layer structure L2 is calculated.

[0012] S3: When the relative density I2 of the first layer structure L1 and the second layer structure L2 calculated in step S2 meets the construction requirements, the third layer structure L3, ..., the Nth layer structure L2 is printed sequentially on the second layer structure L2. N The masses of the first layer structure L1 to the third layer structure L3 are measured sequentially as m3, ..., the masses of the first layer structure L1 to the Nth layer structure L are measured sequentially as m3, ... N The mass is m N The volumes of the first layer L1 to the third layer L3 are measured sequentially as V3, ..., the volumes of the first layer L1 to the Nth layer L are measured as V3, ... N The volume is V NCalculate the relative densities I3, ..., I3 of the first layer L1 to the third layer L3, ..., the relative densities I3 of the first layer L1 to the Nth layer L3, respectively. N relative density I N Based on relative density I N Determine whether the printed structure meets the construction requirements, where N is a natural number.

[0013] The method for monitoring the density of printed structures during the 3D printing process of this invention involves first printing a first layer structure L1 on a support platform, measuring the mass and volume of the formed first layer structure L1, and calculating the relative density I1 of the first layer structure L1. Then, a second layer structure L2 is printed on the first layer structure L1, and the mass and volume of the formed first layer structure L1 and the second layer structure L2 are measured respectively, and the relative density I2 of the first layer structure L1 and the second layer structure L2 is calculated. This process is repeated layer by layer on the second layer structure L2 until the Nth layer structure L1 is printed. N The first layer L1 to the Nth layer L1 of the molded structure were measured respectively. N The mass and volume of the first layer L1 to the Nth layer L are calculated respectively. N relative density I N Based on relative density I N This monitoring method enables rapid and quantitative monitoring of the relative density of the printed structure during the 3D printing process to determine whether the printed structure meets the construction requirements. The operation is simple and the monitoring accuracy is high.

[0014] Furthermore, step S1 includes the following steps:

[0015] S101: The platform of the weighing device is placed within the printing operation range of the 3D printing equipment. The 3D scanner, the automatic leveling base of the weighing device, and the data acquisition instrument are respectively connected to the computer signal. The platform is leveled by the automatic leveling base.

[0016] S102: Adjust the printing parameters and materials of the 3D printing equipment, start the 3D printing equipment and carry out the printing operation of the first layer structure L1 on the support platform. After the first layer structure L1 is formed, the weighing device measures the mass of the first layer structure L1 as m1, pause the printing operation, scan and measure the first layer structure L1 to obtain the point cloud model of the first layer structure L1, and convert the point cloud model into a three-dimensional model. Planarize the bottom of the first layer structure L1 to obtain the volume of the first layer structure L1 as V1.

[0017] S103: Calculate the relative density I1 of the first layer structure L1 according to equation (1), as follows;

[0018]

[0019] Where: ρ sDesign density for the printed structure;

[0020] m1 is the mass of the first layer structure L1;

[0021] V1 is the volume of the first layer structure L1;

[0022] S104: Determine the rationality of relative density I1 according to equation (2). If relative density I1 satisfies equation (2), then the mass of the first layer structure L1 meets the construction requirements. If relative density I1 does not satisfy equation (2), adjust the printing parameters and materials of the 3D printing equipment and reprint the first layer structure L1.

[0023] a≤I1≤b (2)

[0024] Where: a and b are the minimum and maximum allowable relative densities I1 of the first layer structure L1, respectively, and a≥0, b≤1.

[0025] Furthermore, step S2 includes the following steps:

[0026] S201: Continue printing the second layer structure L2 on the first layer structure L1. After the second layer structure L2 is formed, the weighing device measures the mass of the first layer structure L1 and the second layer structure L2 as m2. The printing operation is paused. The 3D scanner scans and measures the first layer structure L1 and the second layer structure L2 to obtain the point cloud model of the first layer structure L1 and the second layer structure L2. The point cloud model is converted into a 3D model, and the bottom of the second layer structure L2 is planarized to obtain the volume V2 of the first layer structure L1 and the second layer structure L2.

[0027] S202: The relative density I2 of the first layer structure L1 and the second layer structure L2 is calculated according to equation (3) as follows:

[0028]

[0029] Where: ρ s Design density for the printed structure;

[0030] m2 is the mass of the first layer structure L1 and the second layer structure L2;

[0031] V2 is the volume of the first layer structure L1 and the second layer structure L2;

[0032] S203: Determine the rationality of relative density I2 according to formula (4). If relative density I2 satisfies formula (4), then the mass of the first layer structure L1 and the second layer structure L2 meets the construction requirements. If relative density I2 does not satisfy formula (4), adjust the printing parameters and materials of the 3D printing equipment and re-establish the first layer structure L1 and the second layer structure L2.

[0033] a≤I²≤b (4)

[0034] Where: a and b are the minimum and maximum allowable relative densities I2 of the first layer structure L1 and the second layer structure L2, respectively, and a≥0, b≤1.

[0035] Furthermore, step S3 also includes the following steps:

[0036] S301: Calculate the first layer structure L1 to the Nth layer structure L according to equation (5). N relative density I N ,as follows:

[0037]

[0038] Where: ρ s Design density for the printed structure;

[0039] m N The first layer structure L1 to the Nth layer structure L N The quality;

[0040] V N The first layer structure L1 to the Nth layer structure L N Volume;

[0041] S302: Determine the relative density I according to equation (6) N The rationality, if relative density I N If equation (6) is satisfied, then the first layer structure L1 to the Nth layer structure L N The quality meets the construction requirements, if the relative density I N If equation (6) is not satisfied, adjust the printing parameters and materials of the 3D printing equipment, and reprint the first layer structure L1 to the Nth layer structure L. N ;

[0042] a≤I N ≤b (6)

[0043] Where: a and b represent the first layer structure L1 to the Nth layer structure L1, respectively. N relative density I N Minimum and maximum values ​​are allowed, and a≥0, b≤1.

[0044] Furthermore, the method for monitoring the density of the printed structure during the 3D printing process also includes step S4, as follows:

[0045] S401: When the Nth layer structure L NAfter printing, a 3D scanner is used to obtain the point cloud model of the recessed part of the bottom surface of the first layer structure L1. The point cloud model is converted into a 3D model, and the bottom of the 3D model of the first layer structure L1 is planarized to obtain the volume of the recessed part of the bottom surface of the first layer structure L1 as V0. Then the volume of the printed structure is V. N -V0;

[0046] S402: Calculate the relative density correction value I of the printed structure according to equation (7). NR ,as follows:

[0047]

[0048] Where: ρ s Design density for the printed structure;

[0049] m N The first layer structure L1 to the Nth layer structure L N The quality;

[0050] V N The first layer structure L1 to the Nth layer structure L N Volume;

[0051] V0 is the volume of the recessed portion at the bottom of the first layer structure L1;

[0052] S403: If the relative density correction value I NR If equation (8) is satisfied, then the quality of the printed structure meets the construction requirements;

[0053] a≤I NR ≤b (8)

[0054] Where: a and b are the relative density correction values ​​I. NR The minimum and maximum values ​​allowed are a and b, and a ≥ 0 and b ≤ 1.

[0055] Furthermore, in step S401, the printed structure is flipped over to expose the recessed portion, and the volume V0 of the recessed portion is obtained by scanning it.

[0056] Furthermore, in step S401, the platform of the weighing device is made of transparent glass, and the volume V0 of the recessed portion is obtained by scanning the three-dimensional scanner. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of an embodiment of the monitoring system for the density of printed structures during the 3D printing process of the present invention;

[0058] Figure 2 This is a flowchart of the method for monitoring the density of printed structures during the 3D printing process of the present invention.

[0059] The numbers in the diagram are as follows:

[0060] Weighing device 100; platform 110; weighing sensor 120; automatic leveling base 130; data acquisition device 140; 3D scanner 200; computer 300; printed structure 400; 3D printing equipment 500. Detailed Implementation

[0061] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the embodiments of the present invention. For ease of description, the terms "upper" and "lower" used below are consistent with the upper and lower directions in the drawings, but this should not be construed as a limitation of the technical solution of the present invention.

[0062] Example 1

[0063] Combination Figure 1 This invention describes a monitoring system for the density of a printed structure during the 3D printing process. It includes a weighing device 100, a 3D scanner 200, and a computer 300 connected to both. The weighing device 100 measures the mass of the printed structure 400, the 3D scanner 200 measures the volume of the printed structure 400, and the computer 300 calculates the relative density of the printed structure 400 based on the acquired data. The weighing device 100 is positioned below the printed structure 400 and includes a support platform 110, load cells 120, an automatic leveling base 130, and a data acquisition device 140. The horizontally placed support platform 110 supports the printed structure 400. At least three load cells 120 are evenly distributed on the bottom of the support platform 110. The data acquisition device 140 is connected to each of the at least three load cells 120. The data acquisition device 140, the automatic leveling base 130, and the 3D scanner 200 are all connected to the computer 300.

[0064] The 3D printing density monitoring system of the present invention includes a weighing device 100, a 3D scanner 200, and a computer 300. The platform 110 of the weighing device 100 supports the printed structure 400, and at least three weighing sensors 120 are evenly distributed on the bottom of the platform 110 to measure the mass of the printed structure 400. The weighing device 100 measures the mass of the currently formed printed structure 400, the 3D scanner 200 measures the volume of the currently formed printed structure 400, and the computer 300 calculates the relative density of the currently formed printed structure 400 based on the mass and volume data, and determines whether the strength and mass of the printed structure 400 meet the construction requirements. During the 3D printing process of components, this monitoring device can measure the mass and volume of the printed structure 400 layer by layer in real time and quantitatively. By calculating the relative density of the printed structure 400 as the basis for judging its strength and mass, it is beneficial to the quality control and safe construction of 3D printing.

[0065] Furthermore, each weighing sensor 120 of the weighing device 100 is connected to an automatic leveling base 130 at its bottom. By adjusting the height of the automatic leveling base 130, the leveling platform 110 can be used.

[0066] To facilitate scanning of the volume of the recessed part at the bottom of the printed structure 400 by the 3D scanner 200, the support 110 of the weighing device 100 is made of transparent glass.

[0067] Example 2

[0068] The 3D printed structure 400 in this embodiment has N layers, which are, from bottom to top, the first layer L1, the second layer L2, ..., the Nth layer L... N The following is combined with Figure 1 and Figure 2 The method for monitoring the density of a 400-fold printed structure during the 3D printing process of this invention is described in detail below:

[0069] S1: Print the first layer structure L1 on the support 110 of the weighing device 100. The weighing sensor 120 measures the mass of the first layer structure L1 after molding as m1. The three-dimensional scanner 200 scans and measures the volume of the first layer structure L1 after molding as V1. Calculate the relative density I1 of the first layer structure L1.

[0070] S2: When the relative density I1 of the first layer structure L1 after molding is calculated in step S1 and meets the construction requirements, the second layer structure L2 is printed on the first layer structure L1. The weighing sensor 120 measures the mass of the first layer structure L1 and the second layer structure L2 after molding as m2. The three-dimensional scanner 200 scans and measures the volume of the first layer structure L1 and the second layer structure L2 after molding as V2. The relative density I2 of the first layer structure L1 and the second layer structure L2 is calculated.

[0071] S3: Print the third layer structure L3, ..., the Nth layer structure L3 sequentially on the second layer structure L2. N The masses of the first layer structure L1 to the third layer structure L3 are measured sequentially as m3, ..., the masses of the first layer structure L1 to the Nth layer structure L are measured sequentially as m3, ... N The mass is m N The volumes of the first layer L1 to the third layer L3 are measured sequentially as V3, ..., the volumes of the first layer L1 to the Nth layer L are measured as V3, ... N The volume is V N Calculate the relative densities I3, ..., I3 of the first layer L1 to the third layer L3, ..., the relative densities I3 of the first layer L1 to the Nth layer L3, respectively. N relative density I N Based on relative density I N Determine whether the printed structure 400 meets the construction requirements, where N is a natural number.

[0072] The method for monitoring the density of printed structures during the 3D printing process of the present invention involves first printing a first layer structure L1 on a support 110, measuring the mass and volume of the first layer structure L1 after molding, and calculating the relative density I1 of the first layer structure L1. Then, a second layer structure L2 is printed on the first layer structure L1, and the mass and volume of the first layer structure L1 and the second layer structure L2 after molding are measured, and the relative density I2 of the first layer structure L1 and the second layer structure L2 is calculated. This process is repeated layer by layer on the second layer structure L2 until the Nth layer structure L1 is printed. N The first layer L1 to the Nth layer L1 of the molded structure were measured respectively. N The mass and volume of the first layer L1 to the Nth layer L are calculated respectively. N relative density I N Based on relative density I N This monitoring method enables rapid and quantitative monitoring of the relative density of the printed structure 400 during the 3D printing process to determine whether the printed structure 400 meets the construction requirements. The operation is simple and the monitoring accuracy is high.

[0073] The specific steps of step S1 are as follows:

[0074] S101: Install the 3D printing structure density monitoring system as described in Embodiment 1, place the platform 110 of the weighing device 100 within the printing operation range of the 3D printing equipment 500, and connect the 3D scanner 200, the automatic leveling base 130 of the weighing device 100 and the data acquisition instrument 140 to the computer 300 respectively, and level the platform 110 through the automatic leveling base 130.

[0075] S102: Adjust the printing parameters and materials of the 3D printing equipment 500, start the 3D printing equipment 500 and carry out the printing operation of the first layer structure L1 on the support platform 110. After the first layer structure L1 is formed, the weighing device 100 measures the mass of the first layer structure L1 as m1, briefly stop the printing operation, and scan and measure the first layer structure L1 by the 3D scanner 200 to obtain the point cloud model of the first layer structure L1. Then, convert the point cloud model into a 3D model and planarize the bottom of the first layer structure L1 to obtain the volume of the first layer structure L1 as V1.

[0076] S103: Calculate the relative density I1 of the first layer structure L1 according to equation (1), as follows;

[0077]

[0078] Where: ρ s The design density is 400 for the printed structure;

[0079] m1 is the mass of the first layer structure L1;

[0080] V1 is the volume of the first layer structure L1;

[0081] S104: Determine the rationality of relative density I1 according to formula (2). If relative density I1 satisfies formula (2), then the mass of the first layer structure L1 meets the construction requirements. If relative density I1 does not satisfy formula (2), adjust the printing parameters and materials of the 3D printing equipment 500 and reprint the first layer structure L1.

[0082] a≤I1≤b (2)

[0083] Where: a and b are the minimum and maximum allowable values ​​of the relative density I1 of the first layer structure L1, respectively, and a≥0, b≤1.

[0084] The specific steps of step S2 are as follows:

[0085] S201: Start the 3D printing equipment 500 and continue printing the second layer structure L2 on the first layer structure L1. After the second layer structure L2 is formed, the weighing device 100 measures the mass of the first layer structure L1 and the second layer structure L2 as m2. Briefly stop the printing operation and scan and measure the first layer structure L1 and the second layer structure L2 with the 3D scanner 200 to obtain the point cloud model of the first layer structure L1 and the second layer structure L2 (excluding the bottom). Convert the point cloud model into a 3D model and flatten the bottom of the second layer structure L2 to obtain the volume V2 of the first layer structure L1 and the second layer structure L2.

[0086] S202: The relative density I2 of the first layer structure L1 and the second layer structure L2 is calculated according to equation (3) as follows:

[0087]

[0088] Where: ρ s The design density is 400 for the printed structure;

[0089] m2 is the mass of the first layer structure L1 and the second layer structure L2;

[0090] V2 is the volume of the first layer structure L1 and the second layer structure L2;

[0091] S203: Determine the rationality of relative density I2 according to equation (4). If relative density I2 satisfies equation (4), then the mass of the first layer structure L1 and the second layer structure L2 meets the construction requirements. If relative density I2 does not satisfy equation (4), adjust the printing parameters and materials of the 3D printing equipment 500 and reprint the first layer structure L1 and the second layer structure L2.

[0092] a≤I²≤b (4)

[0093] Where: a and b are the minimum and maximum allowable relative densities I2 of the first layer structure L1 and the second layer structure L2, respectively, and a≥0, b≤1.

[0094] Step S3 further includes the following steps:

[0095] S301: Calculate the first layer structure L1 to the Nth layer structure L according to equation (5). N relative density I N ,as follows:

[0096]

[0097] Where: ρ s The design density is 400 for the printed structure;

[0098] m N The first layer structure L1 to the Nth layer structure L N The quality;

[0099] V N The first layer structure L1 to the Nth layer structure L N Volume;

[0100] S302: Determine the relative density I according to equation (6) N The rationality, if relative density I N If equation (6) is satisfied, then the first layer structure L1 to the Nth layer structure L N The quality meets the construction requirements, if the relative density I NIf equation (6) is not satisfied, adjust the printing parameters and materials of the 3D printing equipment 500, and reprint the first layer structure L1 to the Nth layer structure L. N ;

[0101] a≤I N ≤b (6)

[0102] Where: a and b represent the first layer structure L1 to the Nth layer structure L1, respectively. N relative density I N Minimum and maximum values ​​are allowed, and a≥0, b≤1.

[0103] Furthermore, the method for monitoring the density of the printed structure 400 during the 3D printing process of the present invention further includes step S4, correcting the relative density of the printed structure 400, the specific steps of which are as follows:

[0104] S401: When the Nth layer structure L N After printing, the weight of the subsequent printed layer causes deformation of the bottom printed layer, forming a recessed portion (not shown). A point cloud model of the recessed portion at the bottom of the first layer structure L1 is obtained using a 3D scanner 200. This point cloud model is then converted into a 3D model. The bottom of the 3D model of the first layer structure L1 is planarized, resulting in a volume of V0 for the recessed portion at the bottom of the first layer structure L1. Therefore, the actual volume of the printed structure 400 is V. N -V0;

[0105] S402: Calculate the relative density correction value I of the printed structure 400 according to equation (7). NR ,as follows:

[0106]

[0107] Where: ρ s The design density is 400 for the printed structure;

[0108] m N The first layer structure L1 to the Nth layer structure L N The quality;

[0109] V N The first layer structure L1 to the Nth layer structure L N Volume;

[0110] V0 is the volume of the recessed portion at the bottom of the first layer structure L1;

[0111] S403: If the relative density correction value I NR If equation (8) is satisfied, then the printed layer structures L1, L2, ... and L... N The quality meets the construction requirements;

[0112] a≤INR ≤b (8)

[0113] Where: a and b are the relative density correction values ​​I. NR The minimum and maximum values ​​allowed are a and b, and a ≥ 0 and b ≤ 1.

[0114] In step S401, the printed structure 400 is flipped over to expose the recessed portion, and the volume V0 of the recessed portion is obtained by scanning it.

[0115] In step S401, the platform 110 of the weighing device 100 is made of transparent glass, which makes it easy for the 3D scanner 200 to directly scan the recessed part to obtain its volume V0.

[0116] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the claims.

Claims

1. A method for monitoring the density of a printed structure during 3D printing, comprising a monitoring system including a weighing device, a 3D scanner, and a computer connected to both devices. The weighing device measures the mass of the printed structure, the 3D scanner measures the volume of the printed structure, and the computer calculates the relative density of the printed structure based on the acquired data. A weighing device is installed below the printed structure. It includes a support platform, load cells, an automatic leveling base, and a data acquisition unit. The support platform supports the printed structure. At least three load cells are evenly distributed on the bottom of the support platform. The data acquisition unit is connected to the signals of at least three load cells. The data acquisition unit, the automatic leveling base, and the 3D scanner are all connected to a computer. The device is characterized by the following steps: S1: Print the first layer of structure on the platform of the weighing device. L 1. Weighing sensor measures the first layer of structure after molding. L The mass of 1 is m 1. A 3D scanner is used to scan and measure the first layer of the formed structure. L The volume of 1 is V 1. Calculate the first layer structure L relative density of 1 I 1; S2: When the first layer structure after molding is calculated in step S1... L relative density of 1 I 1. When construction requirements are met, in the first floor structure L Print the second layer structure on 1 L 2. Weighing sensor measures the first layer of the formed structure. L 1 and second layer structure L The mass of 2 is m 2. The first layer of the formed structure is scanned and measured using a 3D scanner. L 1 and second layer structure L The volume of 2 is V 2. Calculate the first layer structure L 1 and second layer structure L relative density of 2 I 2; S3: When the first layer structure after molding is calculated in step S2... L 1 and second layer structure L relative density of 2 I 2. When construction requirements are met, in the second floor structure L 2. Print the third layer structure layer by layer. L 3, ..., Nth layer structure L N Measure the first layer structure in sequence L 1 to the third layer structure L The mass of 3 is m 3,…, First layer structure L Structure from layer 1 to layer N L N The quality is m N Measure the first layer structure in sequence L 1 to the third layer structure L The volume of 3 is V 3,…, First layer structure L Structure from layer 1 to layer N L N The volume is V N Calculate the first layer structure respectively L 1 to the third layer structure L 3 relative density I 3,…, First layer structure L Structure from layer 1 to layer N L N relative density I N Based on relative density I N Determine whether the printed structure meets the construction requirements, where N is a natural number; S4 includes: S401: When the Nth layer structure L N After printing, a 3D scanner is used to scan and obtain the first layer structure. L 1. The point cloud model of the concave bottom part is converted into a 3D model, and the first layer structure is... L 1. The bottom of the 3D model is planarized to obtain the first layer structure. L The volume of the concave portion at the bottom is 1 V If 0, then the volume of the printed structure is V N - V 0; S402: Calculate the relative density correction value of the printed structure according to equation (7). I NR ,as follows: （7） in: ρ s Design density for the printed structure; m N The first layer structure L Structure from layer 1 to layer N L N The quality; V N The first layer structure L Structure from layer 1 to layer N L N Volume; V 0 represents the first layer of structure. L 1. The volume of the recessed portion at the bottom; S403: If the relative density correction value I NR If equation (8) is satisfied, then the quality of the printed structure meets the construction requirements; （8） in: a , b These are the relative density correction values. I NR The minimum and maximum values ​​are allowed, and a≥0, b≤1.

2. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that, Step S1 includes the following steps: S101: The platform of the weighing device is placed within the printing operation range of the 3D printing equipment. The 3D scanner, the automatic leveling base of the weighing device, and the data acquisition instrument are respectively connected to the computer signal. The platform is leveled by the automatic leveling base. S102: Adjust the printing parameters and materials of the 3D printing equipment, start the 3D printing equipment, and implement the first layer of structure on the support platform. L Print job 1, first layer structure L 1. After molding, the weighing device measures the first layer structure. L The mass of 1 is m 1. Pause printing and use a 3D scanner to measure the first layer structure. L 1. Obtain the first layer structure L A point cloud model of 1 is generated and converted into a 3D model, including the first layer structure. L 1. The bottom layer is planarized to obtain the first layer structure. L The volume of 1 is V 1; S103: Calculate the first layer structure according to equation (1) L relative density of 1 I 1. As follows; （1） in: ρ s Design density for the printed structure; m 1 represents the first layer structure. L The quality of 1; V 1 represents the first layer structure. L Volume of 1; S104: Determine the relative density according to equation (2) I The rationality of 1, if relative density I If equation (2) is satisfied, then the first layer structure L The quality of 1 meets the construction requirements, if the relative density I If equation (2) is not satisfied, adjust the printing parameters and materials of the 3D printing equipment and reprint the first layer structure. L 1; （2） in: a , b The first layer structure L relative density of 1 I 1. Minimum and maximum values ​​are allowed, and a≥0, b≤1.

3. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that, Step S2 includes the following steps: S201: In the first layer structure L Continue printing the second layer structure on page 1. L 2. When the second layer structure L 2. After molding, the weighing device measures the first layer structure. L 1 and second layer structure L The mass of 2 is m 2. Pause printing and use a 3D scanner to measure the first layer structure. L 1 and second layer structure L 2. Obtain the first layer structure L 1 and second layer structure L The point cloud model is converted into a 3D model, and the second layer structure is added. L 2. The bottom layer is planarized to obtain the first layer structure. L 1 and second layer structure L Volume of 2 V 2; S202: Calculate the first layer structure according to equation (3) L 1 and second layer structure L relative density of 2 I 2, as follows: （3） in: ρ s Design density for the printed structure; m 2 represents the first layer structure. L 1 and second layer structure L The quality of 2; V 2 represents the first layer structure. L 1 and second layer structure L Volume of 2; S203: Determine the relative density according to equation (4) I The rationality of 2, if relative density I 2. If equation (4) is satisfied, then the first layer structure L 1 and second layer structure L The quality of item 2 meets the construction requirements, if the relative density... I 2. If equation (4) is not satisfied, adjust the printing parameters and materials of the 3D printing equipment and restructure the first layer. L 1 and second layer structure L 2; （4） in: a , b The first layer structure L 1 and second layer structure L relative density of 2 I 2. Minimum and maximum values ​​are allowed, and a≥0, b≤1.

4. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that, Step S3 further includes the following steps: S301: Calculate the first layer structure according to equation (5) L Structure from layer 1 to layer N L N relative density I N ,as follows: （5） in: ρ s Design density for the printed structure; m N The first layer structure L Structure from layer 1 to layer N L N The quality; V N The first layer structure L Structure from layer 1 to layer N L N Volume; S302: Determine the relative density according to equation (6) I N The rationality of relative density I N If equation (6) is satisfied, then the first layer structure L Structure from layer 1 to layer N L N The quality meets the construction requirements, if the relative density I N If equation (6) is not satisfied, adjust the printing parameters and materials of the 3D printing equipment and reprint the first layer structure. L Structure from layer 1 to layer N L N ; （6） in: a , b The first layer structure L Structure from layer 1 to layer N L N relative density I N Minimum and maximum values ​​are allowed, and a≥0, b≤1.

5. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that: In step S401, the printed structure is flipped over to expose the recessed portion, and the volume of the recessed portion is obtained by scanning it. V 0.

6. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that: In step S401, the platform of the weighing device is made of transparent glass, and the volume of the recessed part is obtained by scanning the three-dimensional scanner. V 0.

7. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that: Each weighing sensor in the weighing device is connected to an automatic leveling base at its bottom.

8. The method for monitoring the density of printed structures during the 3D printing process according to claim 1, characterized in that: The platform of the weighing device is made of transparent glass.

Images