Monitoring and early warning method and system for replacement of powder feeding pipe for 3D printing

Abstract

The invention discloses a monitoring and early warning method and system for replacement of a powder feeding pipe for 3D printing, and the method comprises the steps: carrying out the quantitative calibration of the convergence of the powder feeding pipe in a normal state, and obtaining the initial light powder overlapping length d of the powder feeding pipe; and the width W of the molten pool and the melting deposition height D are measured multiple times in real time, W and D are calculated respectively, if W and D are abnormal, it is judged that abnormal points exist in the powder feeding pipe, and the number of the abnormal points is accumulated and counted. And if the number of the abnormal points is larger than or equal to a set threshold value, forming is paused, the actually-measured light powder overlapping length value dn is collected, and if the difference value of dn and d exceeds the set threshold value, replacement of the powder feeding pipe is prompted. According to the invention, indirect judgment is carried out by adopting the melting width and melting height obtained by the laser coaxial measurement system, and direct judgment is carried out by adopting the lateral photographing data acquisition system, so that timely early warning and reconfirmation are realized, manual monitoring and judgment errors are reduced, the precision of monitoring the service life of the powder feeding pipe is improved, and the practicability is relatively good.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and particularly relates to a monitoring and warning method and system for replacing a powder feeding tube for 3D printing. Background Art

[0002] Laser powder feeding 3D printing is a complex thermoforming process of light-powder interaction. Among them, powder convergence is a key factor affecting part performance and the stability of the forming process. The hardware factor determining powder convergence is mainly the quality of the powder feeding tube. Among them, the traditional method for detecting coaxial powder feeding convergence is the caustic detection method, in which an operator applies a powder trace on a metal plate and a professional checks and determines. Secondly, the existing patent CN202120889399.9 discloses a high-efficiency coaxial powder feeding nozzle convergence detection device. A 360-degree panoramic camera is installed at the lower end of the connecting plate. The transmission screw is threadedly connected with a sliding seat. A laser is arranged on the right side of the sliding seat. The upper end of the transmission screw is fixedly sleeved with a grooved wheel. That is, a plane laser scattered by the powder cone beam is collected by a 360° camera to form an image for judgment. However, during the forming process, the convergence degree of the powder feeding tube is generally observed by on-site operators to determine whether to replace the powder feeding tube. The replacement criteria for the powder tube are inconsistent, which may lead to situations where the operator does not fully identify the effective life of the powder feeding tube, etc. There are potential risks in product quality, and the operation of replacing the powder feeding tube is complex, which will also increase the overall forming time of the part. Summary of the Invention

[0003] The purpose of the present invention is to provide a monitoring and warning method and system for replacing a powder feeding tube for 3D printing, aiming to solve the above problems.

[0004] The present invention is mainly realized through the following technical solutions:

[0005] A monitoring and warning method for replacing a powder feeding tube for 3D printing includes the following steps:

[0006] Step S1: Quantitatively calibrate the convergence of the powder feeding tube in the normal state: Capture a photo of the powder feeding state and process it to obtain the starting light-powder overlap length d of the powder feeding tube as the powder feeding tube life benchmark;

[0007] Step S2: For each slice layer, measure the molten pool width W and the melting deposition height D in real time multiple times;

[0008] Step S3: Calculate ΔW = W - W Q 、ΔD = D - D Q respectively, where W Q is the starting molten pool width calibration value, D Qis the calibration value of the initial melt deposition height; if ΔW is greater than the corresponding set threshold and ΔD is less than the corresponding set threshold, it is determined that there are abnormal points in the powder feeding pipe, and the number of abnormal points is accumulated;

[0009] Step S4: If the number of abnormal points is greater than or equal to the set threshold, the forming process is paused, the cladding head is raised, and the total overlap length of the light powder is collected to obtain the measured light powder overlap length value dn. If the difference between dn and d exceeds the set threshold, a prompt is given to replace the powder feed tube and the current machine tool coordinate value is recorded. Otherwise, the cladding head is lowered and returns to the pause point to continue forming.

[0010] In order to better implement the present invention, further, step S1 includes the following steps:

[0011] Step S11: The optical path is set as the extension line formed by the midpoint of the optical fiber entrance and the midpoint of the cladding head exit, and is drawn in the captured image;

[0012] Step S12: identifying the powder feeding profile of the powder path through the contrast formed by different powder concentrations and fitting it into a straight line;

[0013] Step S13: Measure the distance between the intersection of the powder path and the light path, and then determine the initial light-powder overlap length d.

[0014] In order to better implement the present invention, further, in step S2, the real-time measurement data is randomly collected n times, and n=slice layer area S÷(100-1000).

[0015] In order to better implement the present invention, further, in step S3, when forming the Nth slice layer, the average value of the molten pool width W and the molten deposition height D measured multiple times is taken as the starting molten pool width calibration value W Q and the initial melt deposition height calibration value D Q ; where N≥3.

[0016] In order to better implement the present invention, further, in step S3, if ΔW>0.02WQ and ΔD<0.03DQ, it is determined that there is an abnormal point in the powder feeding pipe.

[0017] In order to better implement the present invention, further, in step S4, if the measured light powder overlapping length value dn≥1.5d, it is prompted to replace the powder feeding tube.

[0018] In order to better implement the present invention, further, in step S4, the cladding head is raised upward by 10 to 20 mm.

[0019] The present invention is mainly achieved through the following technical solutions:

[0020] A monitoring and warning system for replacing the powder feeding tube in 3D printing, which is used to implement the monitoring and warning method for replacing the powder feeding tube in 3D printing as described above, includes a lateral photographing data acquisition system, a laser coaxial measurement system, and a data processing system. The data processing system is respectively connected to the lateral photographing data acquisition system and the laser coaxial measurement system; the data processing system includes an image processing unit, an abnormality statistics unit, and a warning prompt unit;

[0021] The lateral photographing data acquisition system is used to acquire picture information of the powder feeding state;

[0022] The laser coaxial measurement system is used to measure the width of the molten channel and the melting deposition height;

[0023] The image processing unit is used to process the picture information acquired by the lateral photographing data acquisition system to obtain the overlapping length of light and powder;

[0024] The abnormality statistics unit is used to calculate ΔW = W - W Q 、ΔD = D - D Q , respectively compare ΔW and ΔD with the corresponding set thresholds, and count the abnormal points;

[0025] The warning prompt unit is used to compare the measured overlapping length value dn of light and powder with the starting overlapping length d of light and powder, and give a warning for replacing the powder feeding tube.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention utilizes the law that the powder feeding convergence affects the molten pool deposition size, uses the laser coaxial measurement system and the lateral photographing data acquisition system to perform real-time acquisition and measurement, indirectly judges by using the molten width and molten height obtained by the laser coaxial measurement system, and directly judges by using the lateral photographing data acquisition system, that is, realizes timely warning and reconfirmation based on two forms of monitoring, can efficiently and accurately automatically determine the service life of the powder feeding tube, reduces manual observation and judgment, and has good practicability. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the state of single-channel powder feeding;

[0029] Figure 2 It is a schematic diagram of the state of multi-channel powder feeding;

[0030] Figure 3 It is a flowchart of the monitoring and warning method for replacing the powder feeding tube in 3D printing of the present invention;

[0031] Figure 4 It is a schematic structural diagram of the monitoring and warning system for replacing the powder feeding tube in 3D printing of the present invention.

[0032] Wherein: 1 - lateral photographing data acquisition system, 2 - laser coaxial measurement system, 3 - data processing system, 4 - motion mechanism, 5 - powder feeding tube. Specific embodiments

[0033] Embodiment 1:

[0034] A monitoring and warning method for replacing the powder feeding tube in 3D printing, which quantitatively calibrates the convergence of the new powder feeding tube 5 to determine the effective life state of the powder feeding tube 5; measures the size of the laser powder feeding 3D printing molten pool to obtain the values of the molten channel width and the melting deposition height; respectively compares and analyzes the molten channel width, the melting deposition height and the corresponding set thresholds to determine whether the powder feeding tube 5 is abnormal; if the powder feeding tube 5 is abnormal, then conducts a convergence detection again, compares the current life state of the powder feeding tube 5 with the effective life state of the powder feeding tube 5, and finally determines whether to prompt to replace the powder feeding tube 5.

[0035] Preferably, as Figure 3 shown, the present invention includes the following steps:

[0036] Step 1: The lateral photographing data acquisition system 1 quantitatively calibrates the initial convergence of the normal powder feeding tube 5 to determine the initial optical powder overlap length d.

[0037] As Figure 1 and Figure 2 shown, the laser powder feeding forming is divided into two processes: single-path powder feeding and multi-path powder feeding. To further determine the powder feeding convergence, the lateral photographing data acquisition system 1 is used to capture the powder feeding state by taking pictures, and the image processing technology is used to obtain the optical powder overlap length d of the normal powder feeding tube 5. As Figure 1 shown, the optical powder overlap length d refers to the length of the overlap between the powder feeding path and the optical path.

[0038] Specifically, the method for measuring the optical powder overlap length d is as follows:

[0039] 1. Default the optical path as the extension line formed by the midpoint of the fiber optic inlet and the midpoint of the cladding head outlet, and draw it in the captured picture;

[0040] 2. Identify the powder feeding profile of the powder path through the contrast formed by different powder concentrations and fit it into a straight line;

[0041] The contrast is the difference in light and dark contrast shown on the image; after the powder is sent out from the powder feeding tube 5, it forms a powder path, but due to gravity and air flow, the powder is somewhat dispersed, and the powder amount at the center and edge of the powder path is different, that is, the concentration is different. Under the illumination of light, it can be seen that the center of the powder path is brighter and gradually becomes transparent from the inside out. The boundary of the powder path can be identified by taking pictures, and no less than 3 points on the boundary are determined, and a straight line is fitted by a certain point at the outlet of the powder feeding tube 5 and the points on the powder path.

[0042] 3. Measure the distance between the intersection points of the powder path and the optical path to determine the starting optical-powder overlap length d.

[0043] Step 2: The laser coaxial measurement system 2 monitors in real time to obtain the molten pool width and deposition height.

[0044] The laser coaxial measurement system 2 is used to detect the molten pool width and deposition height of laser powder feeding forming in real time, and the molten pool width value W and the melting deposition height D are fed back to the data processing system 3 in real time. When forming one slice layer, the laser is interrupted and the cladding head is lifted by the height of one slice layer, thus completing the forming of one slice layer. The data is randomly collected n times, and the calculation method of the number n is: n = slice layer area S÷(100 - 1000). Among them, the number of data acquisitions is the number of times the laser coaxial measurement system 2 detects the molten pool; according to the requirements of data volume and monitoring accuracy, the denominator of the above formula is set to 100 - 1000. The unit of the area S is mm 2 。

[0045] To avoid errors caused by the instability of the molten pool at the beginning of forming, real-time monitoring starts from the 3rd slice layer, and the average value of the molten channel width and molten pool deposition height data collected in the 3rd layer is used as the starting molten width calibration value W Q and the starting molten height calibration value D Q 。

[0046] The determination of the 3rd slice layer is as follows: the processing program has slice layer display; it can be determined according to the Z-axis machine tool coordinate and the number of Z-axis liftings. The height of each slice layer is a fixed value, and the starting Z-axis machine tool coordinate value is 0.

[0047] Step 3: The data processing system 3 calculates the molten width difference value ΔW and the molten height difference value ΔD during the forming process, and calculates ΔW = W - W Q 、ΔD = D - D Q 。If ΔW > 0.02W appears once Q and ΔD < 0.03D Q at the same time, it is determined as an abnormal point. The data processing system 3 assigns the abnormal point quantity X as 1. Each time it appears, it is counted once, and the X value is accumulated.

[0048] Step 4: When the number of abnormal points X ≥ (5 - 10) times, the forming is paused, and the cladding head is lifted upward by (10 - 20 mm) so that the lateral photographing data acquisition system 1 can collect the entire optical-powder overlap length, and repeat Step 1 to measure the optical-powder overlap length value dn.

[0049] Step 5: If the measured optical-powder overlap length value dn ≥ 1.5d, the system prompts to replace the powder feeding pipe 5 and records the current machine tool coordinate value. Otherwise, resume forming - lower the cladding head and return to the pause point to continue forming.

[0050] During the initial acquisition, the part is only three layers high, which is not high, the forming is stable, the powder convergence point is on the surface of the formed part, and the lateral photography and acquisition system will not be interfered with; if the forming is paused in the subsequent forming process, the cladding head is raised to a certain height for measurement to avoid interference and collision between equipment. At the same time, if the powder convergence is not good, the forming is unstable, and the powder convergence point is no longer on the surface of the part. If it is not raised, it will be interfered with by the part and it is impossible to find the powder convergence point well.

[0051] Example 2:

[0052] A monitoring and early warning method for replacing a powder feeding tube for 3D printing comprises the following steps:

[0053] Step 1: The lateral photographic data acquisition system 1 quantitatively calibrates the initial convergence of the normal powder feeding pipe 5 to determine a benchmark.

[0054] The laser powder forming used is a four-way powder feeding process. The side-viewing data acquisition system 1 is used to capture the powder feeding status of a normal powder feeding tube 5. The image processing technology is used to calculate that the light-powder overlapping length d of the normal powder feeding tube 5 is 5 mm.

[0055] Step 2: The laser coaxial measurement system 2 monitors the molten pool width and deposition height in real time to determine any abnormalities.

[0056] The laser coaxial measurement system 2 is used to detect the width and height of the laser powder feeding forming molten pool in real time, and the molten pool width value W and the molten deposition height D are fed back to the data processing system 3 in real time. The area of the third layer is 10000mm 2 , it is calculated that 10000 / 1000=10 times of data collection is required, and the collected molten pool size is shown in Table 1. Then the average value of all data values of the third layer is calculated to obtain: the initial molten width calibration value W Q =6.45mm, initial melting height calibration value D Q =1.02mm.

[0057] Table 1

[0058] Serial number Width of runner / mm Deposition height of runner / mm 1 6.5 1.0 2 6.4 1.1 3 6.5 1.1 4 6.5 1.0 5 6.4 1.0 6 6.4 1.0 7 6.4 1.1 8 6.5 1.0 9 6.5 1.0 10 6.4 0.9 Average value 6.45 1.02

[0059] Step 3: The data processing system 3 determines whether it is an abnormal point and counts the abnormal points. The data processing system 3 determines whether the number of abnormal points reaches a threshold and determines whether the side-viewing photo data collection system 1 should be used again.

[0060] The data processing system 3 calculates the difference in width ΔW and the difference in height ΔD during the forming process. The calculation formula is: ΔW = WW Q , ΔD=DD Q If ΔW>0.02W occurs once Q And ΔD<0.03DQ If it is determined as an abnormal point, the data processing system 3 assigns the number of abnormal points X as 1. Each occurrence is counted, and the value of X is accumulated. During the forming process, the system monitored a total of 1002 data points, and the number of times determined as abnormal points was 5 times, which has reached the program pause threshold. 10 data points are detected in one slice layer. Here, 1002 refers to the second data of the 103rd layer where the 5th abnormal point occurred.

[0061] Step 4: The program pauses, and the lateral photographing data acquisition system 1 takes a photo of the powder convergence of the current powder feeding tube 5, and the data processing system 3 determines whether to replace the powder tube.

[0062] The forming pauses, and the cladding head is lifted upward by 20 mm, so that the lateral photographing data acquisition system 1 can collect the entire length of the overlapping light and powder. The measured value of the overlapping length of light and powder is dn = 8.2 mm, and the measured value of the overlapping length of light and powder is dn = 1.64d. The system prompts that the powder feeding tube 5 needs to be replaced, and records the current coordinate value, and the operator replaces it.

[0063] Embodiment 3:

[0064] A monitoring and warning system for replacing a powder feeding tube for 3D printing, as Figure 4 shown, includes a lateral photographing data acquisition system 1, a laser coaxial measurement system 2, a data processing system 3, and a motion mechanism 4. Among them, the lateral photographing data acquisition system 1 is mainly used for determining the powder feeding convergence and mainly collects picture information; the laser coaxial measurement system 2 is mainly used for measuring the width of the molten pool and the deposition height, and is used for indirectly determining and warning the powder feeding convergence; the motion mechanism 4 is mainly used for executing actions.

[0065] Preferably, the data processing system 3 includes an image processing unit, an abnormality statistics unit, and a warning prompt unit;

[0066] The image processing unit is used to process the collected picture information by the lateral photographing data acquisition system 1 to obtain the overlapping length of light and powder;

[0067] The abnormality statistics unit is used to calculate ΔW = W - W Q 、ΔD = D - D Q , respectively compare ΔW and ΔD with the corresponding set thresholds, and count the abnormal points;

[0068] The warning prompt unit is used to compare the measured value of the overlapping length of light and powder dn with the initial overlapping length of light and powder d, and give a warning for replacing the powder feeding tube 5.

[0069] The above is only a preferred embodiment of the present invention, and does not make any form of limitation to the present invention. Any simple modification and equivalent change made to the above embodiments according to the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A monitoring and warning method for replacing the powder feeding tube used in 3D printing, characterized in that, It includes the following steps: Step S1: Quantitatively calibrate the convergence of the powder feeding tube in the normal state: Take pictures of the powder feeding state and process them to obtain the initial light powder overlapping length d of the powder feeding tube, which is used as the powder feeding tube life benchmark; Step S2: For each slice layer, measure the molten pool width W and the melting deposition height D in real time and multiple times; Step S3: Calculate respectively and , where W Q is the calibration value of the starting molten pool width, and D Q is the calibration value of the starting melting deposition height; if both is greater than the corresponding set threshold and is less than the corresponding set threshold, it is determined that there is an abnormal point in the powder feeding pipe, and the number of abnormal points is accumulated; Step S4: If the number of abnormal points is greater than or equal to the set threshold, the forming is paused, the cladding head is lifted upward, all the light powder overlapping lengths are collected to obtain the measured light powder overlapping length value dn. If the difference between dn and d exceeds the set threshold, it is prompted to replace the powder feeding tube, and the current machine tool coordinate value is recorded. Otherwise, the cladding head is lowered and the forming continues at the paused position.

2. The monitoring and early warning method for replacing the powder feeding tube for 3D printing according to claim 1, characterized in that The said Step S1 includes the following steps: Step S11: Default the optical path as the extension line formed by the midpoint of the fiber optic inlet and the midpoint of the cladding head outlet, and draw it in the captured picture; Step S12: Identify the powder feeding profile of the powder path through the contrast formed by different powder concentrations and fit it into a straight line; Step S13: Measure the distance between the intersection points of the powder path and the optical path, and then determine the initial light powder overlapping length d.

3. The monitoring and early warning method for replacing the powder feeding tube for 3D printing according to claim 1, characterized in that, In the said Step S2, the real-time measurement data is randomly collected n times, and n = the slice layer area S ÷ (100 - 1000).

4. A monitoring and warning method for replacing the powder feeding tube for 3D printing according to claim 1, characterized in that, In the step S3, when forming the Nth slice layer, the average values of the molten pool widths W measured multiple times and the melting deposition heights D are respectively taken as the starting molten pool width calibration value W Q and the starting melting deposition height calibration value D Q ; where N ≥ 3.

5. A monitoring and warning method for replacing the powder feeding tube for 3D printing according to claim 4, characterized in that, In the step S3, if and appear, it is determined that there is an abnormal point in the powder feeding pipe.

6. The monitoring and early warning method for replacing the powder feeding tube for 3D printing according to claim 1, characterized in that, In the said Step S4, if the measured light powder overlapping length value dn ≥ 1.5d, it is prompted to replace the powder feeding tube.

7. A monitoring and early warning method for replacing a powder feeding tube for 3D printing according to claim 1 or 6, characterized in that, In the said Step S4, the cladding head is lifted upward by 10 - 20 mm.

8. A monitoring and warning system for replacing the powder feeding tube used in 3D printing, which is used to implement the monitoring and warning method for replacing the powder feeding tube used in 3D printing according to any one of claims 1-7, characterized in that, It includes a lateral photographing data acquisition system, a laser coaxial measurement system and a data processing system. The data processing system is respectively connected to the lateral photographing data acquisition system and the laser coaxial measurement system; The data processing system includes an image processing unit, an abnormality statistics unit and a warning prompt unit; The lateral photographing data acquisition system is used to acquire the picture information of the powder feeding state; The laser coaxial measurement system is used to measure the molten channel width and the melting deposition height; The image processing unit is used to process the picture information acquired by the lateral photographing data acquisition system to obtain the light powder overlapping length; The abnormal statistic unit is used to calculate , , and respectively compare , with the corresponding set thresholds, and count the abnormal points; The warning prompt unit is used to compare the measured light powder overlapping length value dn with the initial light powder overlapping length d and give a warning for replacing the powder feeding tube.

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