Fused deposition 3D printing fault monitoring method and 3D printing equipment

Abstract

The fused deposition 3D printing fault monitoring method is applied to 3D printing equipment, the 3D printing equipment at least comprises a spray head, a base plate, a wire feeding module, a fault detection module and a main control system, and the fault detection module comprises a regulation and control assembly and a camera. The method comprises the steps of obtaining model printing information; setting a motion mode of the regulation and control assembly and a collection mode of the camera; acquiring an image of a monitored area; performing fault feature calculation on the monitored area image to obtain a fault feature value; judging whether a printing error occurs or not according to the fault characteristic value; and if a printing error occurs, an error alarm is given out. According to the method, the printing fault caused by the material shortage problem caused by nozzle blockage, material breakage and the like possibly existing in the printing process of the 3D printing equipment can be rapidly monitored in real time, and material waste and printing time waste are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and specifically, to a method for monitoring faults in fused deposition 3D printing and a 3D printing device. Background Art

[0002] The 3D printing device adopts a layer manufacturing method of fused deposition, that is, heating and melting a filamentous thermoplastic material and extruding it through a nozzle with a fine nozzle. During operation, according to the model data, the computer controls the nozzle and the 3D printing substrate to move along a preset path, and cooperates with the extrusion of the material filament by the nozzle to achieve the stacking of materials layer by layer, and finally complete the printing and production of the model. During the long process of 3D printing, when there is a material break, a printing nozzle blockage, or a local overheating, it will cause a filament break in 3D printing. If the filament break situation is not discovered in time, it will cause damage to the model and the 3D printing platform, and waste 3D printing materials and printing time.

[0003] Therefore, there is an urgent need for a technical method for quickly detecting and judging possible filament break faults during 3D printing. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for monitoring faults in fused deposition 3D printing to achieve the purpose of real-time monitoring of possible filament break faults during 3D printing.

[0005] To achieve the above purpose, the present invention adopts the following technical means: A method for monitoring faults in fused deposition 3D printing, based on a 3D printing device, the 3D printing device includes a nozzle, a substrate, and a fault detection module, the nozzle moves translationally along the X direction and Z direction, the substrate moves translationally along the Y direction, the fault detection module includes a camera that moves translationally along the Z direction, in the Z-axis direction, the coordinate values of the camera and the nozzle have the following relationship: C z = B z + e ; Where: e is the error range, , represents the minimum coordinate value that the nozzle can reach when moving along the X negative direction, where C z and C x respectively represent the camera in the Z direction and XThe coordinate value in the direction, B z indicating the coordinate value of the nozzle in Z the direction; The method includes: S1. Obtain the model printing information; S2. Set the movement mode and acquisition mode of the camera; S3. Obtain the image of the camera monitoring area; S4. Calculate the fault characteristics of the monitoring area image to obtain the fault characteristic value; S5. Determine whether a printing error occurs according to the fault characteristic value.

[0006] Preferably, the movement mode of the camera is synchronized with the coordinate value of the nozzle in Z the direction, and the variation range of the coordinate value of the camera in Z the direction is as follows: ; wherein, t i represents the starting printing time of the i th layer slice, B z_start represents the value of the starting printing coordinate of the nozzle in Z the direction, represents the layer spacing, i represents the number of layers of the printed layer slice ，e is the error range.

[0007] Furthermore, the acquisition mode of the camera is to acquire images for each layer slice.

[0008] Even further, the movement mode of the camera is that the coordinate value in Z the direction changes as follows: ; wherein, represents the starting printing time of the th layer slice, represents the value of the starting printing coordinate of the nozzle in the Z direction, represents the layer spacing, i represents the number of layers of the printed layer slice, k is an integer greater than 1, e is the error range.

[0009] Preferably, the acquisition mode of the camera is to start from the k’ th layer, and the camera acquires images every k layer slices.

[0010] Preferably, the k has a value range of 5 to 20.

[0011] Preferably, when calculating the fault features of the monitoring area image, first collect the pixel coordinate sets of the nozzles of the nozzles and the printed layers in each acquired image, as the nozzle pixel coordinate set and the layer pixel coordinate set respectively; determine the fault feature values by processing the Euclidean distances between each pixel coordinate in the nozzle pixel coordinate set and the layer pixel coordinate set.

[0012] The present invention also provides a 3D printing device, which applies the foregoing method for monitoring faults in fused deposition 3D printing, and includes a nozzle, a substrate, a wire feeding module, a fault detection module and a main control system.

[0013] Preferably, the main control system can control the translation of the nozzle in the X direction and the Z direction, and the translation of the substrate in the Y direction, and control the fault detection module to perform fault monitoring. The fault detection module includes a regulation component and a camera. The regulation component can control the camera to translate along the Z direction. The camera is an adjustable focus imaging module, and the optical axis of the camera is parallel to the X axis. In the Y direction, the coordinate value of the camera is the same as that of the nozzle. In the Z direction, the coordinate value of the camera and the coordinate value of the nozzle have the following relationship: C z = B z + e ; Wherein: e is the error range, , represents the minimum coordinate value that the nozzle can reach when moving along the X negative direction, C z and B z respectively represent the coordinate values of the camera and the nozzle in the Z direction.

[0014] Preferably, the shooting field angle fov of the camera satisfies the following relationship: ; Wherein, is the minimum coordinate position that the nozzle can reach when moving in the X axis negative direction, L 1Indicates the closest distance between the nozzle of the nozzle head and the layer sheet.

[0015] Through the 3D printing fault monitoring method provided by the present invention, it is possible to monitor in real time and quickly the printing faults caused by material shortage problems such as nozzle blockage and material breakage that may occur during the printing process of a 3D printing device. Brief Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the functional structure of a 3D printing device provided by the present application.

[0017] Figure 2 It is a schematic diagram of a fused deposition 3D printing fault monitoring method provided by the present application.

[0018] Figure 3 It is a schematic diagram of the first relationship between the camera position and the nozzle head position from the first perspective provided by the present application.

[0019] Figure 4 It is a schematic diagram of the second relationship between the camera position and the nozzle head position from the first perspective provided by the present application.

[0020] Figure 5 It is a schematic diagram of the relationship between the camera position and the nozzle head position from the second perspective provided by the present application.

[0021] Among them, 10 - nozzle head, 20 - substrate, 30 - fault detection module, 301 - camera, 302 - regulation component. Detailed Embodiments

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Refer to Figure 1 , Figure 1 It is a schematic diagram of the functional structure of a 3D printing device. The 3D printing device at least includes a nozzle head 10, a substrate 20, a fault detection module 30, a wire feeding module (not shown in the figure), and a main control system (not shown in the figure). The fault detection module 30 includes a regulation component 302 and a camera 301. The regulation component 302 can control the camera 301 to translate along Z a direction. The fault detection module 30 and the main control system can be communicatively connected. The main control system can control the nozzle head 10 to translate in the X direction and Z direction and the substrate 20 to translate in the YTranslation in the [direction], and control the fault detection module 30 to perform fault monitoring.

[0024] When the 3D printing device performs the printing task of the model, according to the sliced file of the three-dimensional model, obtain the paths of each layer, and determine the moving path of the nozzle 10 in the X and Z directions and the layer spacing between the layers. Under the control of the main control system, the substrate 20 moves along the Y direction and the nozzle 10 moves according to its moving path on the XZ plane and extrudes the filament from the nozzle on the nozzle 10. The hot-melt material adheres to the substrate or the previously cured layer. After each layer is printed, control the nozzle 10 to move up one layer spacing along the Z direction. Repeat this process layer by layer. After all the layers of materials are stacked, the final model object is formed. During the printing process of this 3D printing device, the position of the nozzle 10 in the X direction and Z direction is changing in real time.

[0025] The fault detection module 30 is arranged on one side of the substrate 20. The regulation component 302 is specifically an electric displacement stage, which is used to adjust and control the coordinate position of the camera 301 along the Z direction. The camera 301 is specifically a camera module. The optical axis of the camera 301 is approximately parallel to the X axis. When the fault detection module 30 is fixedly assembled, the coordinate values of the camera 301 in the X direction and in the Y direction are fixed, and the coordinate value in the Z direction changes with the control of the regulation component 302. The position coordinates of the nozzle 10 are represented by the central coordinates of the nozzle on the nozzle 10. Then, the coordinate value of the nozzle 10 in the Y direction is a fixed value, and the coordinate value of the camera 301 in the Y direction is the same as the coordinate value of the nozzle 10 in the Y direction. The coordinate value of the camera 301 in the Z direction and the coordinate value of the nozzle in the Z direction satisfy the following relationship: ; where ; In the above formula, C z represents the coordinate value of the camera 301 in the Z direction; B z represents the coordinate value of the nozzle in the Z direction.

[0026] Whene When = 0, C z = B z . When e is not equal to 0, e the value is similar to an error range, which causes the nozzle B z Although the value of is different from C z , it is still calculated within the 1-degree central field of view of the camera range. Here, 1 degree can also be 1 to 5 degrees. As long as the imaging effect of the camera module is good, 5 degrees is also acceptable. That is, in the above formula can also be replaced by to any number in, including .

[0027] Furthermore, in the above formula, represents the minimum coordinate value that the nozzle can reach when moving along the X negative direction.

[0028] The above C z value setting makes the nozzle 10 and the top several layer slices close to the nozzle 10 within the central field of view of the camera 301. The interesting part in the image collected by the camera 301 is always in the center, which is beneficial to obtaining high-quality images. The imaging quality of the central field of view of the camera 301 is better than that of the edge field of view; on the other hand, in the case of image cropping operations on the interesting part of the original image collected by the camera 301, it is beneficial to improve the efficiency of image cropping.

[0029] As Figure 2 shown, it is a schematic diagram of a 3D printing fault monitoring method provided by the present invention. This method includes the following steps: Step S1: Obtain model printing information; Specifically, when the 3D printing device starts the printing task of the 3D model, the main control system obtains the model printing information according to the slice file of the 3D model. The model printing information includes the value of the starting printing coordinate of the nozzle 10 in the Z direction , the layer spacing and the starting printing time of each layer slice , where i represents the number of layers of the printed layer slice, i = 1 … K , K is the total number of layer slices.

[0030] Step S2: Set the movement mode of the regulation component and the acquisition mode of the camera; The acquisition mode of the camera can be set to have the camera acquire images for each layer slice. Specifically, the camera acquires images at time intervals during the printing process of each layer slice. T The time interval T refers to starting from the printing start time of a layer slice, and the camera acquires an image every T time interval.

[0031] The acquisition mode of the camera can also be set to have the camera start from the k’ th layer, and acquire images every k layer slices. Among them, k’ can be equal to k or not equal to. Specifically, when starting to print the k’ th layer, for the k’ rd layer, the camera acquires images according to the time interval T ; for the k’ + k +1st layer, the camera acquires images according to the time interval T ; for the k’ +2 k +1st layer, the camera acquires images according to the time interval T ; …. Since the camera does not need to acquire images during the printing process of each layer slice, but acquires images after printing every k layer slices, on the one hand, it can reduce the power consumption of the camera. At the same time, if the nozzle does not extrude wire, since the layer spacing is very small, usually 0.1 mm, it is difficult to identify the 0.1 mm fault feature from the acquired images. After the printing duration of k layer slices, this fault distance will increase by k times, making it easy to identify the fault feature on the acquired images and improving the accuracy. Among them, k takes an integer greater than 1. When k takes a value between 5 and 20, it is beneficial to the calculation of fault features in subsequent steps, and when a printing error fault is detected, the waste of materials can be ignored.

[0032] The movement mode of the regulation component 302 refers to the movement trajectory of the regulation component 302 controlling the camera 301 along the Z direction, that is, the way the coordinates of the camera 301 in the Z direction change with time.

[0033] When the acquisition mode of the camera 301 is set to have the camera acquire images for each layer slice, the movement mode of the regulation component 302 is set to be in theY Control the coordinate values of the camera 301 and the coordinate values of the nozzle 10 to be synchronized in the [direction]. Specifically, as Figure 3 and Figure 4 shown, when printing the first layer slice, the regulation component 302 controls the camera 301 to move in the Z direction C z_start = B z_start + e position, where and can be equal, or errors or limitations can be considered, so they can differ by e ; as Figure 3 in PC 1 shown position, during the printing of the first layer slice PB 1 the camera 301 collects images; when the first layer printing is completed, the regulation component 302 controls the camera 301 to move along the Z positive direction by a layer spacing distance , that is, move to the position, that is Figure 4 in PC 2 shown position, and control the camera 301 to collect images during the printing of the second layer slice PB 2 ; and so on, when the i th layer printing is completed, the regulation component 302 controls the camera 301 to move to the position and control the camera 301 to collect images during the printing of the i th layer slice. The coordinate value of the camera 301 in the Z direction C z changes within the following range: ; represents the value of at time C z is , .

[0034] When the acquisition method of the camera is set to start from the k’ rd layer, and the camera acquires images every k layers, when the regulation component 302 controls the coordinate Z of the camera 301 in the C z changes within the following range: ; The above relationship indicates that at moment, the control camera 301 moves in the Z direction to C z , C z The value of is , , is the starting printing time of the i + k layer of the layer stack.

[0035] The above formula describes the correspondence between time and position. At the t moment, Z the coordinate of the camera moves to the position represented by the latter.

[0036] i is not a collection point, but only used to represent a variable integer. This mathematically represents a series of values, i taking 1, 2, 3, 4,... respectively, the corresponding relationship can be obtained. That is to say, t 1 at the moment, the camera is controlled to B z_start + e position, t 2 when, the camera is controlled to position. According to this correspondence, the 3D printing device controls the movement trajectory of the camera.

[0037] Step S3: Obtain the image of the monitored area; During the printing process of each layer of the layer stack, the camera 301 follows the time period T , where T represents the acquisition time interval set for obtaining multiple acquisition images during the printing process of each layer of the layer stack; the image is acquired, and the time period T is a preset value and can be set according to actual needs. For example, if the time period T is 2s, then the camera 301 acquires images every 2s.

[0038] As Figure 3 , Figure 4 or Figure 5 shown, the monitored area includes the nozzle of the nozzle 10 and several layers of the printed layer stack near the nozzle.

[0039] Since the shooting optical axis of the camera 301 is parallel to the X direction, the coordinate of the camera 301 in the Z direction and the nozzle 10 alongZ The coordinates in the direction are kept consistent. Considering the setting of the movement mode of the control component 302 in step S2, the monitored area is always covered by the central field of view of the camera 301. At the same time, considering that only a small central part of the original image captured by a camera with a large shooting field of view contains the monitored area, on the one hand, each frame of the original image captured needs to be cropped, which increases the processing flow and time. On the other hand, it also wastes the resolution of the camera. As Figure 5 shown, therefore, by designing the shooting field of view of the camera 301 fov to satisfy the following relational expression: ; wherein, is the minimum coordinate position that the nozzle of the nozzle 10 can reach when moving in the negative direction of the X axis. L 1 represents the closest distance between the nozzle of the nozzle 10 and the layer. If the acquisition method of the camera is to set the camera to collect images of each layer and a nozzle non-spinning fault occurs, L 1 the value of is approximately one layer spacing distance , and the layer spacing is generally 0.1 - 0.3 mm; if the acquisition method of the camera is to set the camera to start from the k’ layer, and the camera collects images every k layers, and a nozzle non-spinning (wire breakage) fault occurs, L 1 the value of is at most k layer spacing distances .

[0040] In the optical imaging design of the camera, the design of the camera that satisfies the above fov relational expression not only has a lower design difficulty, is easy to obtain high-spatial-resolution image imaging quality, but also has a large coverage rate of the monitored area in the original image, and subsequent cropping processing is not required.

[0041] Step S4: Calculate the fault characteristics of the monitored area image to obtain the fault characteristic value; First, perform conventional image processing operations on the original image captured by the camera 301, such as grayscale processing, denoising, filtering, etc. to obtain the first image. Then, use a feature recognition algorithm to obtain the pixel coordinate set of the nozzle image and the pixel coordinate set of the printed layer image in the first image. The pixel coordinate set of the nozzle in the first image refers to the coordinate set of all pixels that make up the nozzle image in the first image, denoted as the nozzle pixel coordinate set, which also includes the pixels of the wire inside the nozzle. The pixel coordinate set of the printed layer in the first image refers to the coordinate set of all pixels that make up the printed layer image in the first image, denoted as the layer pixel coordinate set. Calculate the closest pixel pairs in the nozzle pixel coordinate set and the layer pixel coordinate set. In the specific implementation process, the Euclidean distance can be calculated between the coordinate of a pixel in the nozzle pixel coordinate set and each pixel coordinate in the layer pixel coordinate set to obtain a series of Euclidean distances. Traverse all pixels in the nozzle pixel coordinate set to obtain the Euclidean distances between each pixel coordinate in the nozzle pixel coordinate set and each pixel coordinate in the layer pixel coordinate set, and take the minimum value of these Euclidean distances as the fault feature value.

[0042] In step S5, determine whether a printing error has occurred based on the fault feature value. If it is determined that a printing error has occurred, go to step S6; if it is determined that no printing error has occurred, return to step S3.

[0043] The threshold value of the fault feature value for a printing fault is preset and can be set according to actual requirements. For example, the threshold can be determined based on the distance between the nozzle pixels and the layer pixels during normal printing. Another example is that when collecting images of the monitored area for each layer, the threshold can be equal to or less than , which is the layer spacing distance described above, that is, the layer thickness. Compare the fault feature value obtained in step S4 with the threshold. If it exceeds the threshold, it indicates that the nozzle is broken or not extruding wire, and it is determined that a printing error has occurred, and step S6 will be entered. If the fault feature value is within the threshold range, it indicates that the nozzle is not broken or is extruding wire normally, and it is determined that no printing error has occurred, and return to execute step S3.

[0044] Step S6 issues a printing error alarm and stops the printing task; Specifically, if it is confirmed that a printing error has occurred, a printing error alarm is issued. The printing error alarm can be displayed in text form on the control panel or can be given as a sound warning.

[0045] Through the 3D printing fault monitoring method provided by the present invention, it is possible to monitor in real time and quickly the printing faults caused by material shortage problems such as nozzle blockage and material breakage that may exist during the printing process of 3D printing equipment.

[0046] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for monitoring faults in fused deposition 3D printing, characterized in that, Based on a 3D printing device, the 3D printing device includes a nozzle, a substrate, and a fault detection module. The nozzle translates along the X direction and Z direction, the substrate translates along the Y direction, the fault detection module includes a camera that translates along the Z direction. In the Z axis direction, the coordinate values of the camera and the nozzle have the following relationship: C z = B z + e ； Wherein: e is the error range, , B x_min represents the minimum coordinate value that the nozzle can reach when moving along the X negative direction, where C z and C x respectively represent the coordinate values of the camera in the Z direction and the X direction, B z represents the coordinate value of the nozzle in the Z direction; The method includes: S1. Obtain model printing information; S2. Set the movement mode and acquisition mode of the camera; S3. Obtain the image of the camera monitoring area; S4. Calculate the fault features of the monitoring area image to obtain fault feature values; S5. Determine whether a printing error has occurred according to the fault feature values.

2. The method for monitoring faults in fused deposition 3D printing according to claim 1, wherein The movement mode of the camera is to be synchronized with the coordinate value of the nozzle in Z direction, and the variation range of the coordinate value of the camera in Z direction is as follows: ； Among them, t i represents the starting printing time of the i layer slice, B z_start represents the value of the starting printing coordinate of the said nozzle in the Z direction, represents the layer spacing, i represents the number of layers of the printed layer slice, e is the error range.

3. A method for monitoring faults in fused deposition 3D printing according to claim 1 or 2, characterized in that, The acquisition mode of the camera is to acquire images for each layer slice.

4. A method for monitoring faults in fused deposition 3D printing according to claim 1, characterized in that, The movement mode of the camera is that the coordinate value in the Z direction changes as follows: ； Among them, t i*k represents the starting printing time of the i + k th layer slice, B z_start represents the value of the starting printing coordinate of the said nozzle in the Z direction, represents the layer spacing, i represents the number of layers of the printed layer slices, k is an integer greater than 1, e is the error range.

5. The method for monitoring faults in fused deposition 3D printing according to claim 1 or 4, characterized in that, The acquisition method of the camera starts from the k’ th layer, and for every k layers, the camera performs image acquisition.

6. The method for monitoring the failure of fused deposition 3D printing according to claim 5, wherein, The k has a value range of 5 to 20.

7. A method for monitoring faults in fused deposition 3D printing according to claim 1, characterized in that, When calculating the fault features of the monitoring area image, first collect the pixel coordinate sets of the nozzles of the print head and the printed layer slices in each acquired image, as the nozzle pixel coordinate set and the layer slice pixel coordinate set respectively; determine the fault feature values by processing the Euclidean distances between each pixel coordinate in the nozzle pixel coordinate set and the layer slice pixel coordinate set.

8. A 3D printing device, characterized in that, Applying a fused deposition 3D printing fault monitoring method according to any one of claims 1 to 7, including a print head, a substrate, a wire feeding module, a fault detection module and a main control system.

9. A 3D printing device according to claim 8, wherein, The main control system controls the translation of the nozzle in the X direction and the Z direction, and the translation of the substrate in the Y direction, and controls the fault detection module to perform fault monitoring. The fault detection module includes a regulation component and a camera. The regulation component can control the camera to translate along the Z direction. The camera is an adjustable focus imaging module, and the optical axis of the camera is parallel to the X axis. In the Y direction, the coordinate value of the camera is the same as that of the nozzle. In the Z direction, the coordinate value of the camera and the coordinate value of the nozzle have the following relationship: C z = B z + e ； Wherein: e is the error range, , B x_min represents the minimum coordinate value that the nozzle can reach when moving along the X negative direction, C z and B z respectively represent the coordinate values of the camera and the nozzle in the Z direction.

10. A 3D printing device according to claim 9, characterized in that, The shooting field of view angle of the camera fov Satisfies the following relationship: ； Among them, B x_min is the minimum coordinate position that the nozzle can reach when moving in the negative direction of the X axis, L 1 indicating the closest distance between the nozzle of the nozzle and the layer.

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