An apparatus and method for electric arc additive manufacturing of composite materials based on visual sensing

Abstract

The application discloses an arc additive manufacturing composite material device and method based on visual sensing. The method belongs to the technical field of additive manufacturing. In the forming process, when the arc area fed back by the computer processing unit is greater than the set area, the powder feeding gas flow is controlled to be lower than the maximum gas flow; and when the arc area fed back by the computer processing unit is smaller than the set area, the powder feeding gas flow is controlled to be a set value. The method utilizes the interval of arc extinguishing in the CMT-WAAMT forming to complete the delivery of the reinforcing particles into the molten pool, avoids the influence of the powder delivery gas flow on the arc combustion, can greatly improve the stability of the CMT-WAAM particle reinforced metal matrix composite material forming process, and utilizes the bypass powder feeding mode to realize the composition customization of different position regions of a part, thereby providing a new idea for the arc additive manufacturing particle reinforced metal matrix gradient composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric arc additive manufacturing, in particular to an electric arc additive manufacturing composite material device and method based on visual sensing. BACKGROUND

[0002] Cold metal transfer wire arc additive manufacturing (CMT-WAAM) uses metal wire as raw material, through a computer numerical control (CNC) system, adopts the principle of slicing, layering and discrete superposition, and accumulates layer by layer according to the specified path to obtain a near-net metal part. This technology is fast in manufacturing, flexible in forming, and low in cost, and is widely used in many important industries such as aerospace, biomedicine, and automation. However, the inherent high heat input and large temperature gradient of this technology cause the prepared parts to exhibit uneven microstructure, composition segregation, and anisotropy in mechanical properties. A large number of studies have shown that particle reinforcement can effectively regulate the WAAM microstructure and improve the mechanical properties such as strength and modulus of CMT-WAAM materials.

[0003] Currently, the introduction of reinforcing particles in the CMT-WAAM molten pool mainly includes the following three methods: surface coating of particles, powder core wire, and bypass delivery of particles. The surface coating of particles is convenient for adjusting the type and size of the particles, but the content of the reinforcing particles in the molten pool is limited, and the surface coating of particles needs to wait for the deposited layer to cool down to a lower temperature before each deposition layer, which is low in forming efficiency. When using powder core wire for additive manufacturing, the particles are encapsulated in the droplet after the wire is melted, which ensures the uniform distribution of the reinforcing particles in the molten pool and guarantees the high utilization rate of the reinforcing particles. However, the preparation process of the powder core wire is complicated, and it is not easy to adjust the type, size, and delivery amount of the reinforcing particles. When using bypass delivery of particles, the type, size, and input amount of the particles can be flexibly controlled, thereby realizing the composition customization of CMT-WAAM parts at different positions. However, the airflow of the delivered particle powder will interfere with the stable combustion of the electric arc, affecting the stability of CMT-WAAM forming.

[0004] In summary, the existing methods are difficult to adjust the type, size, and content of the introduced reinforcing particles while ensuring the stability of the CMT-WAAM forming process, that is, it is difficult to realize the stable forming of CMT-WAAM of customized composition and high-performance composite material parts. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide an electric arc additive manufacturing composite material device and method based on visual sensing to solve the problem of difficult stable forming in the CMT-WAAM forming process in the prior art.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A method for arc additive manufacturing of composite materials based on visual sensing, the method comprising the steps of:

[0008] S1, setting the cold metal arc additive manufacturing process parameters;

[0009] S2, setting the welding gun position and high-speed camera height, the camera focus being the welding gun and the deposition layer;

[0010] S3, during the cold metal arc additive manufacturing process, the high-speed camera captures the arc image, when the arc area is greater than the set area, the gas flow output by the powder feeder is reduced to below the maximum gas flow; when the arc area is less than the set area, the gas flow output by the powder feeder is increased to the set powder feeding gas flow;

[0011] S4, repeating S3 until the molding is completed.

[0012] Further improvements of the present application are:

[0013] Preferably, in S3, the arc area is the white area after the binaryzation processing of the high-speed camera captured picture.

[0014] Preferably, in S3, the set area is 0.6 times the maximum arc area, and the maximum arc area is the arc area in the combustion stage of the cold metal arc additive manufacturing process without powder feeding gas.

[0015] Preferably, in S3, it is judged whether the arc inclination factor is less than 0.6, if the arc inclination factor is less than 0.6, the powder feeding gas flow of the powder feeder is reduced until the arc inclination factor reaches 0.6, and the powder feeding gas flow of the powder feeder remains unchanged.

[0016] Preferably, the arc inclination factor is the ratio S1 / S2 of the arc areas on both sides of the powder feeding boundary line, the powder feeding boundary line is the vertical direction of the welding wire, S1 is the arc area on the side of the powder feeding boundary line close to the powder feeding pipe, and S2 is the arc area on the side of the powder feeding boundary line close to the molded workpiece.

[0017] Preferably, in S1, the process parameters include wire feeding speed, powder feeding speed and welding speed.

[0018] Preferably, in S3, when the high-speed camera captures the arc image, the shooting angle is perpendicular to the moving path of the powder feeding pipe.

[0019] An apparatus for arc additive manufacturing of composite materials based on visual sensing for implementing the above method, comprising a molding unit, a powder feeding unit, a visual sensing unit and a computer processing unit;

[0020] The powder feeding unit is used to deliver powder materials to the molding unit, and the molding unit manufactures workpieces through the cold metal arc additive manufacturing process.

[0021] The powder feeding unit and the computer processing unit are electrically connected, and the visual sensing unit and the computer processing unit are electrically connected.

[0022] Preferably, the visual sensing unit comprises a high-speed camera and a filter, and the filter is arranged in front of the lens of the high-speed camera.

[0023] Preferably, the computer unit comprises a high-speed camera image processing module and a powder feeding module; the high-speed camera image processing module is used for displaying the image processed by the high-speed camera, and the powder feeding module is used for controlling the powder feeding speed of the powder feeding unit.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The application discloses a method for arc additive manufacturing of composite materials based on visual sensing. The method controls the powder feeding gas flow to be lower than the maximum gas flow when the arc area fed back by the computer processing unit is greater than the set area, and controls the powder feeding gas flow to be the set value when the arc area fed back by the computer processing unit is less than the set area during the forming process. The method utilizes the gap of arc extinguishing in the CMT-WAAM forming to complete the delivery of the reinforcing particles into the molten pool, avoids the influence of the powder delivery gas flow on the arc combustion, can greatly improve the stability of the CMT-WAAM particle reinforced metal matrix composite material forming process, and realizes the composition customization of parts in different position areas by using the bypass powder feeding mode, thereby providing a new idea for the arc additive manufacturing of particle reinforced metal matrix gradient composite materials.

[0026] Further, the method prepares the metal matrix composite material by the bypass powder feeding arc additive manufacturing mode, facilitates the realization of the composition customization of parts in different position areas, and has unique advantages in the preparation of gradient composite materials. In addition, for common forming technologies such as TIG and MIG, the application also provides a way to improve the stability of the bypass powder feeding arc additive manufacturing of metal matrix composite materials, that is, the arc image is extracted by online monitoring, and the bypass powder feeding gas flow is controlled in real time by the computer under the premise of ensuring the stable combustion of the arc.

[0027] The application also discloses a device for arc additive manufacturing of composite materials based on visual sensing, which is composed of a shaping unit, a powder feeding unit, a visual sensing unit and a computer processing unit. The powder feeding mode is bypass powder feeding; the visual sensing unit is mainly a high-speed camera, which can shoot the arc shape; the computer processing unit can perform binary processing on the arc image transmitted by the visual sensing unit and calculate key information such as arc area and inclination. Communication is established between the powder feeding unit and the computer processing unit, so that the powder feeding gas flow can be controlled in real time by the computer. The application is particularly suitable for cold metal arc additive manufacturing (CMT-WAAM) of particle reinforced metal matrix composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The application is a device for arc additive manufacturing of composite materials based on visual sensing;

[0029] Figure 2 The application monitors the CMT-WAAM "arc striking-arc burning-arc extinguishing" image;

[0030] Figure 3 The application is a schematic diagram of the arc inclination factor calculation method. DETAILED DESCRIPTION

[0031] The embodiments of the application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application.

[0032] The first aspect of the application discloses a device for arc additive manufacturing of composite materials based on visual sensing, which comprises a shaping unit, a powder feeding unit, a visual sensing unit and a computer processing unit.

[0033] The shaping unit comprises a welding machine, a welding torch, a robot and a robot control cabinet. Communication is established between the welding machine and the robot, and the shaping process is controlled by the robot control cabinet, including wire feeding speed, welding torch moving speed, starting and ending of shaping.

[0034] The powder feeding unit comprises a powder feeder, a powder feeding pipe and a clamp. The powder feeding mode is bypass powder feeding; the powder feeding speed is controlled by the gas flow of the powder feeder, and the powder feeder can change the powder feeding gas flow in real time; the inner diameter of the powder feeding pipe is not more than 1.5 mm.

[0035] A visual sensing unit, including a high-speed camera, a filter. The filter is externally embedded in front of the lens of the high-speed camera; the high-speed camera is used to monitor the image of the electric arc, and the monitoring frame rate can be artificially controlled. Specifically, the frame rate of the high-speed camera is not less than 1000 frames / s, so as to meet the shooting requirements.

[0036] A computer processing unit, including high-speed camera image processing software. A communication is established between the computer processing unit and the powder feeding unit, so that the powder feeding gas flow can be adjusted in real time based on the monitored electric arc shape.

[0037] The computer processing unit, the visual sensing unit and the powder feeding unit are electrically connected, so that the computer processing unit can collect the pictures taken by the visual sensing unit in real time, and the powder feeding gas flow can be controlled by the computer processing unit in real time. Specifically, the computer controls according to the data information analyzed by the image processing unit.

[0038] It should be particularly pointed out that the device is particularly suitable for CMT-WAAM forming metal matrix composite. The method related to the present application will be described below taking the CMT-WAAM forming metal matrix composite process as an example.

[0039] In the second aspect of the present application, a method for electric arc additive manufacturing of composite materials based on visual sensing is provided. The method is aimed at the CMT-WAAM forming characteristics, and includes the stages of arc starting, arc burning and arc extinguishing. In the CMT-WAAM arc burning stage, in order to ensure the stability of the electric arc, the powder feeder gas flow is controlled to be lower than A max , so as to ensure the stability of the electric arc burning. In the electric arc extinguishing stage, the powder feeder gas flow is controlled to increase to A0.

[0040] The specific steps of the CMT-WAAM forming particle reinforced composite material are as follows:

[0041] Step 1, setting the CMT-WAAM forming metal matrix composite process, including wire feeding speed, powder feeding speed and welding speed.

[0042] Step 2, positioning the welding gun position to be perpendicular to the substrate and maintaining a proper distance from the substrate; positioning the high-speed camera position to be consistent with the height of the welding gun, and the shooting angle is perpendicular to the moving path of the powder feeding pipe.

[0043] Step 3, running the visual sensing unit and the computer processing unit, running the powder feeding unit, the powder feeder gas flow is A0, running the CMT-WAMM forming program, the wire end first arcs, the high-speed camera of the visual sensing unit detects the electric arc image and transmits it to the computer processing unit, and the electric arc area information is obtained through binary processing. When the electric arc area reaches 0.6S max , it is considered that the CMT-WAAM forming enters the arc burning stage, and the computer controls the powder feeder gas flow to decrease to Amax Subsequently, the CMT-WAAM forming enters the arc extinguishing stage, when the arc area is reduced to 0.6S max Then, the computer controls the powder feeder gas flow to increase to A0. Thus, one cycle of the CMT-WAAM forming is completed.

[0044] Further, considering that the welding wire diameter is known, the arc area can be calculated by comparing the welding wire diameter with the arc size and scaling it in proportion.

[0045] Step 4, the CMT-WAAM enters the second forming cycle, and the visual sensing unit transmits the acquired arc image to the computer processing unit, which judges and controls the powder feeder gas flow according to step 3. This process is repeated until the forming is completed.

[0046] Further, in step 3, the arc extinguishing stage is determined by the computer processing unit, and the determination basis is the arc area after binary processing.

[0047] Further, the arc area is the area of the white region after binary processing of the white bright arc monitored by the high-speed camera.

[0048] Further, referring to Figure 2 When the arc area is greater than 0.6S max , it is determined that the CMT-WAAM forming enters the burning stage, and the computer controls the powder feeder gas flow to decrease to A max ; when the arc area is less than 0.6S max , it is determined that the CMT-WAAM forming enters the extinguishing stage, and the computer controls the powder feeder gas flow to increase to A0. Wherein S max is the arc area in the burning stage under the specific CMT-WAAM process parameters without the influence of the powder feeding gas, and its value changes with the CMT-WAAM process parameters. A0 is the preset powder feeding gas flow, and A max is the maximum gas flow that does not affect the stable burning of the arc, and its value is related to the arc inclination factor I.

[0049] Further, the powder feeding amount can also be calculated according to the arc inclination factor, referring to Figure 3 , wherein the arc inclination factor I is calculated as follows: taking the vertical straight line where the welding wire is located as the boundary, measuring the areas S1 and S2 on the left and right sides of the boundary, and S1 / S2 is the arc inclination factor I. It should be particularly pointed out that S1 is the area on the side close to the powder feeding pipe, and S2 is the arc area on the side close to the forming workpiece.

[0050] Example 1

[0051] Taking the CMT-WAAM particle reinforced metal matrix composite material as an example.

[0052] The metal matrix is 304L stainless steel, the powder is WC, and the particle size of the WC powder is 17-53 μm.

[0053] The steps of the metal matrix composite material preparation method are as follows:

[0054] Step 1, set the CMT-WAAM wire feeding speed to 9 m / min, the welding speed to 7 mm / s, the protective gas flow to 15 L / min, and the powder feeding gas flow to 8 L / min.

[0055] Step 2, position the welding gun so that it is perpendicular to the substrate, and the tail of the welding gun is 1.2 cm away from the upper surface of the substrate; position the high-speed camera so that its height is consistent with that of the welding gun, and the shooting angle is perpendicular to the movement path of the welding gun.

[0056] Step 3, turn on the high-speed camera, set the frame rate to 3600 fps, and run the computer processing unit. Turn on the powder feeder to deliver WC powder at a gas flow rate of 8 L / min, and then immediately run the CMT-WAMM forming program. The end of the welding wire is ignited, the high-speed camera detects the arc image, and transmits it to the computer processing unit. The arc area information is obtained through binary processing. When the detected arc area reaches 24 mm 2 , it is considered that the CMT-WAAM forming enters the arc burning stage, and the computer controls the powder feeder gas flow to reduce to below 2 L / min. Subsequently, the CMT-WAAM forming enters the arc extinguishing stage, and when the arc area decreases to 24 mm 2 , the computer controls the powder feeder gas flow to increase to 8 L / min. Thus, one cycle of CMT-WAAM forming is completed.

[0057] Step 4, CMT-WAAM enters the second forming cycle. According to the description in Step 3, the visual sensing unit transmits the acquired arc image to the computer processing unit, and the computer judges and controls the powder feeder gas flow. This process is repeated until the forming is completed.

[0058] This embodiment uses CMT-WAAM technology, and there is an arc extinguishing stage in the forming process. This embodiment utilizes the interval of arc extinguishing to deliver WC powder to the molten pool, and there is no problem of powder feeding gas flow disturbing the arc.

[0059] Example 2

[0060] Taking MIG-WAAM particle reinforced metal matrix composite material as an example.

[0061] The metal matrix is 304L stainless steel, the powder is WC, and the particle size of the WC powder is 17-53 μm.

[0062] The metal matrix composite material preparation method steps are as follows:

[0063] Step 1, set the MIG-WAAM wire feeding speed to 7 m / min, the welding speed to 5 mm / s, the protective gas flow to 15 L / min, and the powder feeding gas flow to 8 L / min;

[0064] Step 2, position the welding gun so that the welding gun is perpendicular to the substrate, and the tail of the welding gun is 1.2 cm away from the upper surface of the substrate; position the high-speed camera so that the height of the camera is consistent with the welding gun, and the shooting angle is perpendicular to the movement path of the welding gun;

[0065] Step 3, turn on the high-speed camera, set the frame rate to 1000 fps, and run the computer processing unit. Turn on the powder feeder to deliver WC powder at a gas flow of 8 L / min, and then immediately run the CMT-WAMM forming program. The end of the welding wire is arced, the high-speed camera detects the arc image and confirms the position of the welding wire, which is transmitted to the computer processing unit, and the arc inclination factor I is judged after binary processing. The arc inclination judgment is as follows: taking the straight line where the welding wire is located as the boundary, calculating the areas S1 and S2 on the left and right sides of the boundary, and S1 / S2 is the arc inclination factor. When the arc inclination factor is less than 0.6, the computer controls the powder feeder to reduce the powder feeding gas flow until the arc inclination factor reaches 0.6, and the computer controls the powder gas flow to remain unchanged.

[0066] This embodiment adopts MIG-WAAM technology, and there is a problem of powder feeding gas flow disturbing the arc during the forming process. This embodiment can efficiently obtain the bypass powder feeding gas flow that can ensure the stability of the arc shape under specific MIG-WAAM process parameters by judging the arc inclination through the visual sensing unit and the computer processing unit. In addition, by setting the bypass powder feeding gas flow, the composition design of the enhanced particle content of the WAAM part can be achieved to a certain extent.

[0067] From the above analysis, it can be seen that in the CMT-WAAM manufacturing process, the method of the present application determines the change of the arc area through the high-speed camera, and uses the gap of arc extinguishing to complete the delivery of the enhanced particles into the molten pool, avoiding the influence of the powder delivery gas flow on the arc burning, and can greatly improve the stability of the CMT-WAAM particle reinforced metal matrix composite material forming process.

[0068] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0069] In the description of the application, it is necessary to understand that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the features defined as "first", "second" can be explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "a plurality of" is two or more, unless otherwise specified. In the description of the application, the first feature "above" or "below" the second feature can include the first and second features in direct contact, or the first and second features not in direct contact but in contact through another feature between them.

[0070] In the description of the application, the first feature "above", "above" and "above" the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the first feature is higher than the second feature in height.

[0071] In the description of the application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0072] In the description of the application, the description of the terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the application. In this specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0073] Although embodiments of the application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirit of the application, and the scope of the application is defined by the claims and their equivalents.

[0074] The above descriptions are only the preferred embodiment of the application, not intended to limit the application and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for arc additive manufacturing of composite materials based on vision sensing, characterized in that, The method includes the following steps: S1, set the process parameters for cold metal arc additive manufacturing; S2, set the welding torch position and high-speed camera height, with the camera focus on the welding torch and the deposited layer; S3, In the cold metal arc additive manufacturing process, a high-speed camera captures an image of the arc. When the arc area is larger than a set area, the gas flow rate output by the powder feeder is reduced to below the maximum gas flow rate; when the arc area is smaller than the set area, the gas flow rate output by the powder feeder is increased to the set powder feeding gas flow rate; the set area is 0.6 times the maximum arc area, and the maximum arc area is the arc area during the combustion stage of the cold metal arc additive manufacturing process when there is no powder feeding gas. In S3, the gas flow rate output by the powder feeder can also be calculated by the arc tilt factor to determine whether the arc tilt factor is less than 0.

6. If the arc tilt factor is less than 0.6, the powder feeder's airflow is reduced until the arc tilt factor reaches 0.6, and the powder feeder's airflow remains unchanged. The arc tilt factor is the ratio S1 / S2 of the arc areas on both sides of the powder feeding boundary line. The powder feeding boundary line is the vertical direction of the welding wire. S1 is the arc area on the side of the powder feeding boundary line closer to the powder feeding pipe, and S2 is the arc area on the side of the powder feeding boundary line closer to the formed workpiece. S4, repeat S3, until molding is complete.

2. The method for arc additive manufacturing of composite materials based on vision sensing according to claim 1, characterized in that, In S3, the arc area is the area of ​​the white region after binarization of the image captured by the high-speed camera.

3. The method for arc additive manufacturing of composite materials based on vision sensing according to claim 1, characterized in that, In S1, the process parameters include wire feeding speed, powder feeding speed, and welding speed.

4. The method for arc additive manufacturing of composite materials based on vision sensing according to claim 1, characterized in that, In S3, when the high-speed camera captures an arc image, the shooting angle is perpendicular to the moving path of the powder feeding tube.

5. An apparatus for implementing the method of claim 1, using vision sensing-based arc additive manufacturing of composite materials, characterized in that, It includes a molding unit, a powder feeding unit, a vision sensing unit, and a computer processing unit; The powder feeding unit is used to supply powder to the forming unit, which manufactures workpieces using a cold metal arc additive manufacturing process. The powder feeding unit and the computer processing unit are electrically connected, and the visual sensing unit and the computer processing unit are also electrically connected.

6. The apparatus for arc additive manufacturing of composite materials based on vision sensing according to claim 5, characterized in that, The visual sensing unit includes a high-speed camera and a filter, with the filter positioned in front of the high-speed camera lens.

7. The apparatus for arc additive manufacturing of composite materials based on vision sensing according to claim 5, characterized in that, The computer processing unit includes a high-speed camera image processing module and a toner feeding module; the high-speed camera image processing module is used to display the images processed by the high-speed camera, and the toner feeding module is used to control the toner feeding speed of the toner feeding unit.

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