Intelligent powder amount control method and system for additive manufacturing equipment

Abstract

The invention is suitable for the technical field of additive manufacturing, and provides an intelligent powder amount control method and system for additive manufacturing equipment, and the method comprises the following steps: 1, calculating the maximum value SNmax of the sum of process weighted sectional areas of all parts in a unit segmentation region in an Nth layer; 2, composite multiple factors of intelligent powder amount control are determined, wherein the composite multiple factors comprise SNmax, a part layer thickness value coefficient k and a dynamic compensation value E; step 3, calculating the pre-estimated required powder spreading amount F of the current layer based on multiple composite factors; 4, a closed-loop feedback method is adopted, the forming area obtained after powder laying is shot through a camera, image processing is carried out, the dynamic compensation value E is adjusted according to the processing result, and dynamic control over the powder amount is achieved; the problems that powder loss is too much, powder laying is insufficient and unstable, and powder amount estimation is difficult to adapt to complex processes and parts are solved, so that the system ensures that the powder laying amount is always in the optimal parameter under the condition that manual intervention is not needed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing technology, and particularly relates to an intelligent powder amount control method and system for an additive manufacturing device. BACKGROUND

[0002] Selective Laser Melting (SLM) technology is a technology route with wide application and development prospect among many additive manufacturing technologies. With the continuous increase of the forming work area of the SLM device and the increasing complexity of the machined parts, the accuracy requirements for powder consumption in the forming process are higher.

[0003] Currently, there are many deficiencies in the powder consumption control of SLM devices:

[0004] Generally, the devices use manual setting of fixed powder consumption per layer for printing processing. Since the part has different forming cross-sectional shapes and areas that are not fixed, it is difficult to determine the powder consumption setting value, and problems such as insufficient or excessive powder laying are prone to occur. Insufficient powder laying will cause part remelting and gap defects, and excessive powder laying will lead to rapid powder consumption, excessive powder return, and other problems, increasing powder pollution, loss, turnover labor, and downtime probability.

[0005] A few devices adjust the powder consumption according to the size parameters of the machined parts, but only consider the influence of the workpiece size on the powder laying amount, ignoring the influence of the layer thickness parameters and laser process parameters on the powder laying amount, and the layer thickness data is not a simple linear relationship. At the same time, this scheme cannot dynamically feedback and adjust abnormal conditions during printing, and cannot flexibly adapt to complex processes such as variable layer thickness and shell extraction printing.

[0006] Some devices use machine vision for powder laying monitoring, but most of them are only used for powder laying fault monitoring, alarm, fault identification, etc. Usually, it only prompts manual adjustment of the powder consumption setting, and cannot completely solve the problem of insufficient powder laying. It also cannot identify the problem of excessive powder laying, and if the manual processing is not timely, it will appear the defect marks caused by long forming intervals.

[0007] A few devices use residual powder detection schemes, but since the shape and structure of each layer of the part are not consistent and not completely filled with all the forming space, the powder demand of the current layer area with processing is greater than that of the current layer area without processing, and the powder laying situation cannot be simply judged from the uniformity or weight of the residual powder.

[0008] Therefore, in view of the above status, it is urgent to provide an intelligent powder amount control method and system for an additive manufacturing device to overcome the deficiencies in current actual applications. SUMMARY

[0009] The application aims to provide an intelligent powder amount control method and system for additive manufacturing equipment, effectively solving the problems in the background art.

[0010] The application is implemented as an intelligent powder amount control method and system for additive manufacturing equipment, which comprises the following steps:

[0011] Step 1: Calculate the maximum value S of the sum of the process weighted cross-sectional areas of each part in each unit division area in the Nth layer Nmax ;

[0012] Step 2: Determine the composite multi-factor of intelligent powder amount control, including S Nmax , part layer thickness value coefficient k and dynamic compensation value E;

[0013] Step 3: Calculate the estimated powder amount F required for the current layer based on the composite multi-factor;

[0014] Step 4: Use a closed-loop feedback method, take pictures of the formed area after powder laying by a camera and perform image processing, adjust the dynamic compensation value E according to the processing result, and realize dynamic control of the powder amount.

[0015] As a further scheme of the application: the calculation method of the sum of the process weighted cross-sectional areas is as follows:

[0016] Divide the scanning area of the Nth layer into several unit division areas with a unit width perpendicular to the powder laying direction;

[0017] Calculate the area to be scanned for each part in each division area;

[0018] Obtain the process package coefficient corresponding to each part; calculate the sum S of the process weighted cross-sectional areas of all parts in each division area n ; take the maximum value of each S n as S Nmax .

[0019] As a further scheme of the application: the formula for calculating the powder amount F in step 3 is as follows:

[0020] F = I * S * k / J + E;

[0021] Where I is the powder amount base, J is the maximum forming cross-sectional area of the equipment, and S is the S Nmax of the current layer.

[0022] As a further scheme of the application: in step 3, the determination step of the dynamic compensation value E is as follows:

[0023] When the equipment is ready to start the printing process in the initial stage, read the S Nmax of the Nth layer to be scanned, and let S0 = S Nmax ;

[0024] If the current layer is the first layer, let S1=S0, E0=E2;

[0025] If the current layer is not the first layer, subtract S0 from S1, compare the difference with △S, and have a preset upper limit S H , a preset upper limit S L , △S=S0-S1, and let E1=E0;

[0026] If △S is less than the preset upper limit S L , that is, △S L , let E0=E1-X, S1=S0, where X is a preset adjustment value;

[0027] If △S is greater than the preset upper limit S H , that is, S H <△S, let E0=E1+X, S1=S0;

[0028] If S L ≤△S≤S H , let E0=E1, S1=S1;

[0029] Let S=S0, and finally determine the dynamic compensation value E=E0.

[0030] As a further scheme of the application: the specific steps of the closed-loop feedback method in step 4 are:

[0031] After the device performs the powder spreading action, the camera takes a photo of the formed area after powder spreading, and obtains the gray value A after image processing;

[0032] Calculate A and the preset gray threshold B to obtain A-B;

[0033] If A-B≤C, it is judged that the powder spreading is normal, and a laser scanning action is performed, where C is a preset value;

[0034] If A-B>C, it is preliminarily judged that the powder spreading has defects, let E0=E+y, S1=S, and perform a second powder spreading action, where y is a preset powder adjustment value;

[0035] After the second powder spreading, the camera takes a photo again to judge, if A-B≤C at this time, the printing continues normally, and the next powder amount calculation uses the modified E0 and S1, if A-B>C at this time, an alarm signal is output to prompt manual processing.

[0036] An intelligent powder amount control system for an additive manufacturing device, which executes the method as described above, the system comprises:

[0037] A calculation module for calculating the maximum value S of the sum of the process weighted sectional areas of each part in the unit division area of the Nth layerNmax ;

[0038] a factor determination module configured to determine a composite multi-factor of intelligent powder amount control, including S Nmax , a part layer thickness value coefficient k, and a dynamic compensation value E;

[0039] a powder amount estimation module configured to calculate an estimated powder amount F required for a current layer based on the composite multi-factor;

[0040] a closed-loop feedback module configured to adjust powdering parameters according to image data.

[0041] As a further scheme of the present application, the calculation module comprises:

[0042] a region segmentation unit configured to segment a scanning region of an Nth layer into a plurality of unit segmentation regions with a unit width X perpendicular to a powdering direction;

[0043] an area calculation unit configured to calculate an area required for scanning each part in each segmentation region;

[0044] a process package coefficient acquisition unit configured to acquire a process package coefficient corresponding to each part according to a preset mapping set;

[0045] a maximum value determination unit configured to calculate a sum S n of process weighted cross-sectional areas of all parts in each segmentation region and take a maximum value as S Nmax .

[0046] As a further scheme of the present application, the powder amount estimation module comprises:

[0047] a process package coefficient storage unit configured to store a mapping relationship between parts and process package coefficients;

[0048] a layer thickness coefficient calculation unit configured to determine a layer thickness coefficient k according to a layer thickness h;

[0049] a dynamic compensation calculation unit configured to calculate and adjust a dynamic compensation value E.

[0050] As a further scheme of the present application, the closed-loop feedback module comprises:

[0051] a camera configured to take a photo of a formed region after powdering;

[0052] an image processing unit configured to process the photo and adjust the dynamic compensation value E according to a processing result to realize dynamic control of the powder amount.

[0053] As a further scheme of the present application, the system further comprises:

[0054] an alarm module configured to output an alarm signal when a gray value still does not meet a requirement after continuous powdering for two times.

[0055] Compared with the prior art, the present application has the following advantages:

[0056] The present application proposes the maximum value S of the sum of the process weighted cross-sectional area of each part in the unit division area in the Nth layer Nmax as an important powder amount estimation basis in the intelligent powder amount control strategy, solving the problem of interference caused by overlapping of multiple part contours or excessive support lines, which cannot be solved by the powder amount estimation scheme using only the sum of the cross-sectional lengths of each division line.

[0057] Through reasonable and accurate process weighted cross-sectional area calculation, combined with the layer thickness coefficient factor, based on the device powder basic quantity and the device maximum forming cross-sectional area, and with the dynamic adjustment function, relatively accurate powder amount data of each layer can be obtained, solving the problem of large error and inapplicability of the conventional estimation model for powder estimation under complex model and complex process conditions, enhancing the estimation reliability and stability, and eliminating the need for manual intervention during printing.

[0058] The specific method of combining camera shooting to extract gray value for closed-loop feedback adjustment of powder amount enables the powder amount estimation model to have a closed-loop feedback function, solving the missing part of the conventional scheme, ensuring that the powder laying action no longer affects the printing success rate in terms of powder supply, improving the yield, reducing labor, reducing powder loss and defective product loss, etc. DETAILED DESCRIPTION

[0059] The technical solutions of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0060] The present application will be further explained and described below in combination with specific embodiments.

[0061] The intelligent powder amount control method for additive manufacturing equipment provided by the embodiments of the present application has the following specific steps:

[0062] First, the maximum value S of the sum of the process weighted cross-sectional area of each part in the unit division area in the Nth layer (N=1, 2, 3,...) is proposed Nmax as an important powder amount estimation basis in the intelligent powder amount control strategy.

[0063] The calculation logic of S ND is as follows:

[0064] (1) Read the device powder laying direction, and divide the scanning area of the Nth layer (N=1, 2, 3,...) into a plurality of unit division areas with a unit width L (which can be set) perpendicular to the powder laying direction;

[0065] (2) Calculate the area of each part that needs to be scanned in each divided area, such as the area of part a that needs to be scanned in the nth area, which is calculated as S na , and the area of part b that needs to be scanned is calculated as S nb , and so on;

[0066] (3) Read the mapping set according to the preset value: f1: part → process package coefficient, such as part a corresponding to read process package coefficient D a , part b corresponds to read process package coefficient D b , and so on; Calculate the sum of the process weighted cross-sectional area of all parts in each divided area: S n = S na *D a +S nb *D b +S nc *D c +…;

[0067] (4) Compare the sum of the process weighted cross-sectional area of each part in each divided area, and take the maximum value as the maximum value of the process weighted cross-sectional area of each part in the nth layer in the unit divided area S Nmax ;

[0068] (4) Store the mapping set f2: N → S Nmax , for reading and calling when calculating the powder amount of each layer. This scheme solves the problem of interference caused by multiple part contour overlaps or excessive support lines that cannot be solved by the powder amount estimation scheme using only the sum of the cross-sectional lengths of the divided lines.

[0069] Propose to use composite multi-factor as intelligent powder control strategy powder estimation calculation factor. Including but not limited to:

[0070] (1) The maximum value of the sum of the process weighted cross-sectional area of each part in the nth layer in the unit divided area S Nmax , which includes the part scanning area factor and the process package factor;

[0071] (2) Part layer thickness value coefficient k, which is derived from the mapping set: f3: layer thickness h → layer thickness coefficient k. This factor is adjusted for variable layer thickness printing and inconsistent powder consumption for various layer thicknesses;

[0072] (3) Dynamic compensation value E, which will fluctuate with the size of S Nmax to dynamically adjust the compensation size. This factor is a dynamic compensation factor that plays a role in the model, and this factor is also a parameter adjusted by the closed-loop regulation function.

[0073] Based on the above multiple factors, the intelligent powder control strategy is proposed. In the initial stage of the device, the S Nmax , and S0=S Nmax , determine whether the current layer to be scanned is the first layer, if it is the first layer, then S1=S0, E0=E2 (preset default value), if the current layer to be scanned is not the first layer, then S0 and S1 are subtracted, the difference is compared with △S, there is a preset upper limit of deviation value S H , the preset upper limit of deviation value S L , △S=S0-S1, and E1=E0. If △S is less than the preset upper limit of deviation value S L , that is, △S L , E0=E1-X, S1=S 0， , where X is a preset adjustment value; if △S is greater than the preset upper limit of deviation value S H , that is, S H <△S, E0=E1+X, S1=S 0， , where X is a preset adjustment value; if S L ≤△S≤S H , then E0=E1, S1=S1. The values generated above are S=S0, dynamic compensation value E=E0, layer thickness coefficient k, powder base I, and device maximum forming cross-sectional area J, according to the formula to calculate the current layer estimated powder amount F, the formula can be simplified as: F=I*S*k / J+E.

[0074] Based on the above, we propose a further closed-loop feedback method. After the device performs the powder spreading action, the camera is used to take pictures of the formed area after powder spreading, and the gray value A is obtained after image processing. Calculate A-B with the preset gray threshold B to determine the relationship between A-B and C. If A-B≤C, it is determined that the powder spreading is normal, and the laser scanning action is executed; if A-B>C, it is preliminarily determined that the powder spreading has defects, at this time the abnormal information feedback by the camera causes the parameter of the dynamic adjustment value E to be adjusted, so as to achieve the effect of closed-loop feedback, E0=E+y, S1=S, where y is a preset powder adjustment value. Then perform the second powder spreading action, and continue to judge by camera shooting after the second powder spreading action is completed. If A-B≤C at this time, continue normal printing, and the values of E0 and S1 modified before due to closed-loop feedback will be used for analysis and calculation before the next powder amount F calculation. If A-B>C still, after two times of powder spreading with the powder amount calculated accurately by the intelligent powder control strategy, it is still not satisfied, it means that there is other abnormality, then output an alarm signal to prompt manual processing. The above process is continuously looped and judged in the printing process.

[0075] In the embodiment, the application can obtain relatively accurate powder amount data of each layer by reasonable and accurate process weighted cross-sectional area calculation, combination of layer thickness coefficient factor, and dynamic adjustment function based on the universality of the parameters of device powder basis quantity and device maximum forming cross-sectional area, and on the basis of the specific method of closed-loop feedback adjustment of powder amount by combining camera shooting and extraction of gray value, the dynamic stability of powder amount is ensured as a whole, the powder amount is appropriate, various problems such as excessive powder loss, insufficient powder laying, instability, and difficulty in adapting complex process and parts for powder amount estimation are solved, so that the system ensures that the powder laying amount is always at the optimal parameter without manual intervention.

[0076] Meanwhile, according to the powder laying structure of the device, the method is also compatible with one-way powder laying and two-way powder laying.

[0077] The embodiment of the application also provides an intelligent powder amount control system for an additive manufacturing device, which executes the method as described above, and the system comprises:

[0078] A calculation module is configured to calculate a maximum value S of a sum of process weighted cross-sectional areas of parts in each unit division region in the Nth layer Nmax ; the calculation module comprises:

[0079] A region division unit is configured to divide a scanning region of the Nth layer into a plurality of unit division regions with a unit width X perpendicular to a powder laying direction;

[0080] An area calculation unit is configured to calculate areas to be scanned by the parts in each division region;

[0081] A process package coefficient acquisition unit is configured to acquire process package coefficients corresponding to the parts according to a preset mapping set;

[0082] A maximum value determination unit is configured to calculate a sum S of process weighted cross-sectional areas of all parts in each division region n , and take a maximum value as S Nmax ;

[0083] A factor determination module is configured to determine a composite multi-factor of intelligent powder amount control, including S Nmax , a part layer thickness value coefficient k, and a dynamic compensation value E;

[0084] A powder amount estimation module is configured to calculate a required powder laying amount F of a current layer based on the composite multi-factor; the powder amount estimation module comprises:

[0085] A process package coefficient storage unit is configured to store a mapping relationship between the parts and the process package coefficients;

[0086] A layer thickness coefficient calculation unit is configured to determine a layer thickness coefficient k according to a layer thickness h;

[0087] A dynamic compensation calculation unit is configured to calculate and adjust a dynamic compensation value E.

[0088] A closed-loop feedback module is configured to adjust the powder spreading parameters according to the image data; the closed-loop feedback module comprises:

[0089] A camera is configured to take a photo of the shaped area after powder spreading;

[0090] An image processing unit is configured to process the photo and adjust the dynamic compensation value E according to the processing result to realize dynamic control of the powder amount.

[0091] The system further comprises:

[0092] An alarm module is configured to output an alarm signal when the gray value does not meet the requirement after two consecutive powder spreadings.

[0093] In summary, the present application can obtain relatively accurate powder amount data of each layer by means of reasonable and accurate process weighted cross-sectional area calculation, combination of layer thickness coefficient factor, and dynamic adjustment function based on the device powder basic amount and the device maximum shaping cross-sectional area universal parameter, and on the basis of the above, the specific method of adjusting the powder amount by means of closed-loop feedback adjustment of the gray value extracted by the camera shooting, overall ensures the dynamic stability of the powder amount, ensures the appropriate powder amount, solves the problems of excessive powder loss, insufficient powder spreading, instability, powder amount prediction difficult to adapt to complex processes, parts, and various problems, and ensures that the system is always in the best parameters without manual intervention.

[0094] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for intelligent powder quantity control in additive manufacturing equipment, characterized in that, The method comprises the following steps: Step 1: Calculate the maximum value S of the sum of the process weighted sectional areas of the parts in the unit division area in the Nth layer Nmax ; Step 2: Determine the composite multi-factors of intelligent powder volume control, including S Nmax , part layer thickness value coefficient k and dynamic compensation value E; Step 3: estimating the powdering amount F of the current layer based on composite multi-factors; Step 4: adopting a closed-loop feedback method, taking a photo of the formed area after powdering by a camera and performing image processing, adjusting the dynamic compensation value E according to the processing result, and realizing dynamic control of the powdering amount.

2. The intelligent powder volume control method for an additive manufacturing apparatus according to claim 1, wherein, The calculation method of the sum of the process weighted sectional areas is: Dividing the scanning area of the Nth layer into a plurality of unit division areas with a unit width X perpendicular to the powdering direction; Calculating the area of each part to be scanned in each division area; Obtain the process package coefficient corresponding to each part; calculate the sum S of the process weighted sectional area of all parts in each segmentation area n ; take the maximum value in each S n as S Nmax .

3. The intelligent powder volume control method for an additive manufacturing apparatus according to claim 1, wherein, The formula for calculating the powdering amount F in step 3 is: F = I * S * k / J + E; where I is the powder basis, J is the maximum cross-sectional area of the device, S is the S Nmax .

4. The intelligent powder volume control method for an additive manufacturing apparatus according to claim 1, wherein, In step 3, the determination steps of the dynamic compensation value E are as follows: At the beginning of the initial phase of the device, read the S of the N layer to be scanned Nmax , let S0 = S Nmax ; If the current layer is the first layer, let S1 = S0 and E0 = E2; If the current layer is not the first layer, then S0 is subtracted from S1, and the difference is compared with ΔS, and if the preset deviation upper limit S H , the preset deviation upper limit S L , ΔS = S0 - S1, and E1 = E0. If the value of ΔS is less than the upper limit S of the preset deviation value, the value of S is adjusted to S0-ΔS. L That is, ΔS < S L Let E0 = E1 - X and S1 = S0, where X is a preset adjustment value. If ΔS is greater than the upper limit of the preset deviation value S H That is, S H If ΔS is less than S, let E0=E1+X and S1=S0. If S L ≤△S≤S H then let E0 = E1, S1 = S1; Let S = S0, and finally determine the dynamic compensation value E = E0.

5. The intelligent powder volume control method for an additive manufacturing apparatus according to claim 1, wherein, The specific steps of the closed-loop feedback method in step 4 are as follows: After the device performs the powdering action, the camera takes a photo of the formed area after powdering, obtains the gray value A after image processing; Calculate A-B by taking A and the preset gray threshold B; If A-B ≤ C, it is judged that the powdering is normal, and the laser scanning action is performed, wherein C is a preset value; If A-B > C, it is preliminarily judged that the powdering is defective, let E0 = E + y and S1 = S, and perform the second powdering action, wherein y is a preset powder adjustment value; After the second powdering, the camera takes a photo again to judge, if A-B ≤ C at this time, continue normal printing, and the powdering amount calculation adopts the modified E0 and S1 next time, if A-B > C at this time, output an alarm signal to prompt manual processing.

6. An intelligent powder volume control system for an additive manufacturing apparatus, performing the method of any one of claims 1-4, characterized in that, The system comprises: a calculating module for calculating a maximum value S of the sum of the process weighted sectional areas of the parts in the unit division area in the Nth layer Nmax ; A factor determining module is configured to determine a composite multi-factor of intelligent powder volume control, including S Nmax , a part layer thickness value coefficient k, and a dynamic compensation value E. A powdering amount estimation module for estimating the powdering amount F of the current layer based on composite multi-factors; A closed-loop feedback module for adjusting the powdering parameters according to image data.

7. The intelligent powder volume control system for an additive manufacturing apparatus of claim 6, wherein, The calculation module comprises: A region division unit for dividing the scanning area of the Nth layer into a plurality of unit division areas with a unit width X perpendicular to the powdering direction; An area calculation unit for calculating the area of each part to be scanned in each division area; A process package coefficient acquisition unit for acquiring the process package coefficient corresponding to each part according to a preset mapping set; The maximum value determining unit is configured to calculate the sum S of the process-weighted sectional areas of all parts in each division region n and take the maximum value as S Nmax .

8. The intelligent powder volume control system for an additive manufacturing apparatus of claim 6, wherein, The powdering amount estimation module comprises: A process package coefficient storage unit for storing the mapping relationship between the parts and the process package coefficients; A layer thickness coefficient calculation unit for determining the layer thickness coefficient k according to the layer thickness h; A dynamic compensation calculation unit for calculating and adjusting the dynamic compensation value E.

9. The intelligent powder volume control system for an additive manufacturing apparatus of claim 6, wherein, The closed-loop feedback module comprises: A camera for taking a photo of the formed area after powdering; An image processing unit for processing the photo, adjusting the dynamic compensation value E according to the processing result, and realizing dynamic control of the powdering amount.

10. The intelligent powder volume control system for an additive manufacturing apparatus of claim 6, wherein, The system further comprises: An alarm module for outputting an alarm signal when the gray value does not meet the requirements after two consecutive powderings.