Electric arc additive manufacturing composite material device and method based on visual sensing

Abstract

The invention discloses an electric arc additive manufacturing composite material device and method based on visual sensing. According to the method, in the forming process, when the arc area fed back by a computer processing unit is larger 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. According to the method, conveying of reinforced particles into a molten pool is completed through arc extinguishing gaps in CMT-WAAMT forming, the influence of powder conveying airflow on arc combustion is avoided, the stability of the CMT-WAAM particle reinforced metal matrix composite forming process can be greatly improved, component customization of different position areas of parts can be achieved through a bypass powder feeding mode, and the forming efficiency of the CMT-WAAM particle reinforced metal matrix composite is improved. And a new thought is provided for electric arc additive manufacturing of the particle reinforced metal matrix gradient composite material.

Description

Technical Field

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

[0002] Cold Metal Transition Arc Additive Manufacturing (CMT-WAAM) uses metal wire as raw material, and through the CNC system (Computer Numerical Control, CNC), adopts the principle of slicing, layering and discrete superposition, and stacks layer by layer along the specified path to obtain near-net metal parts. This technology has fast manufacturing, flexible forming, and low cost, and is widely used in many important industries such as aerospace, biomedicine, and automation. However, the inherent problems of this technology, such as high heat input and large temperature gradient, make the prepared parts show problems such as uneven organization, component segregation, and anisotropy of mechanical properties. A large number of studies have shown that particle reinforcement can effectively regulate WAAM organization and improve the mechanical properties of CMT-WAAM materials such as strength and modulus.

[0003] At present, the methods of introducing reinforcing particles into the CMT-WAAM melt pool mainly include surface coating particles, powder core wires and bypass conveying particles; among them, the surface coating particles are easy to introduce particles, and it is easy to adjust the particle type and particle size, but the content of reinforcing particles in the melt pool is limited, and each layer is deposited, and the surface coating of the particles can only be carried out after the deposited layer cools to a lower temperature, which has low forming efficiency. When additive manufacturing is performed with powder core wires, the particles are coated in the molten droplets after the wire is melted, so that the particles can be evenly distributed in the melt pool, ensuring the high utilization rate of the reinforcing particles, but the powder core wire preparation process is cumbersome, and this method is not easy to adjust the type, particle size and conveying amount of the reinforcing particles. When conveying particles through bypass, the particle type, particle size and input amount can be flexibly controlled, so as to achieve the customization of the components at different positions of CMT-WAAM parts. However, the airflow conveying the particle powder will interfere with the stable combustion of the arc and affect the forming stability of CMT-WAAM.

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

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide an 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. In order to achieve the above object, the present invention adopts the following technical solutions: A method for arc additive manufacturing of composite materials based on visual sensing, the method comprising the following steps: S1, setting cold metal arc additive manufacturing process parameters; S2, setting the welding gun position and high-speed camera height, with the camera focusing on the welding gun and the deposited layer; S3, during the cold metal arc additive manufacturing process, a high-speed camera takes an arc image. When the arc area is larger than the 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; S4, repeat S3 until the molding is completed.

[0006] A further improvement of the present invention is: Preferably, in S3, the arc area is the area of ​​the white region after binarization processing of the image taken by the high-speed camera.

[0007] 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 when there is no powder feeding gas.

[0008] Preferably, in S3, it is determined whether the arc inclination factor is less than 0.6. If the arc inclination factor is less than 0.6, the powder feeding airflow of the powder feeder is reduced until the arc inclination factor reaches 0.6 and the powder feeding airflow of the powder feeder remains unchanged.

[0009] Preferably, the arc inclination factor is the ratio S1 / S2 of the arc areas on both sides of the powder feeding boundary, the powder feeding boundary is the vertical direction of the welding wire, S1 is the arc area on the side of the powder feeding boundary close to the powder feeding pipe, and S2 is the arc area on the side of the powder feeding boundary close to the formed workpiece.

[0010] Preferably, in S1, the process parameters include wire feeding speed, powder feeding speed and welding speed.

[0011] Preferably, in S3, when the high-speed camera captures the arc image, the shooting angle is perpendicular to the moving path of the powder delivery tube.

[0012] A device 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; The powder feeding unit is used to feed powder material to the molding unit, and the molding unit manufactures the workpiece by a cold metal arc additive manufacturing process; The powder delivery unit is connected to the computer processing unit by electrical signals, and the visual sensing unit is connected to the computer processing unit by electrical signals.

[0013] Preferably, the visual sensing unit comprises a high-speed camera and a filter, and the filter is arranged in front of the high-speed camera lens.

[0014] 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 to display the image processed by the high-speed camera, and the powder feeding module is used to control the powder feeding speed of the powder feeding unit.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a method for arc additive manufacturing of composite materials based on visual sensing. In the forming process of this method, when the arc area fed back by the computer processing unit is larger than the set area, the powder feeding gas flow rate is controlled to be lower than the maximum gas flow rate, and when the arc area fed back by the computer processing unit is smaller than the set area, the powder feeding gas flow rate is controlled to be the set value. This method utilizes the gap of arc extinguishing in CMT-WAAM forming to complete the delivery of reinforced particles to the molten pool, avoiding the influence of powder delivery airflow on arc burning, and can greatly improve the stability of the forming process of CMT-WAAM particle-reinforced metal-based composite materials. By utilizing the bypass powder feeding method, the composition customization of different position areas of the parts can be realized, providing a new idea for arc additive manufacturing of particle-reinforced metal-based gradient composite materials.

[0016] Furthermore, the method prepares metal-based composite materials by bypass powder feeding arc additive manufacturing, which facilitates the customization of the components of parts in different position areas and has unique advantages in preparing gradient composite materials. In addition, for common forming technologies such as TIG and MIG, the present invention also provides a way to improve the stability of the forming process of bypass powder feeding arc additive manufacturing metal-based composite materials, that is, to extract arc images through online monitoring, and to control the bypass powder feeding gas flow in real time through a computer under the premise of ensuring stable arc combustion.

[0017] The present invention also discloses a device for arc additive manufacturing of composite materials based on visual sensing, which is composed of a forming unit, a powder feeding unit, a visual sensing unit and a computer processing unit. The powder feeding method is bypass powder feeding; the main body of the visual sensing unit is a high-speed camera, which can take pictures of 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 the arc area and inclination. Communication is established between the powder feeding unit and the computer processing unit, so that the powder feeding gas flow rate can be controlled by the computer in real time. The present invention is particularly suitable for forming particle-reinforced metal matrix composite materials by cold metal transfer wire and arc additive manufacturing (CMT-WAAM). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention discloses an arc additive manufacturing composite material device based on visual sensing; Figure 2 The CMT-WAAM "arc start-arc burning-arc extinction" image monitored by the present invention; Figure 3 Schematic diagram of the arc tilt factor calculation method of the present invention. DETAILED DESCRIPTION

[0019] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0020] A first aspect of the present invention discloses an arc additive manufacturing composite material device based on visual sensing, which includes a forming unit, a powder feeding unit, a visual sensing unit and a computer processing unit.

[0021] The forming unit includes a welding machine, a welding gun, a robot, and a robot control cabinet. Communication is established between the welding machine and the robot, and the forming process is controlled by the robot control cabinet, including the wire feeding speed, the welding gun moving speed, and the start and end of forming.

[0022] The powder feeding unit includes a powder feeder, a powder feeding tube, and a clamp. The powder feeding method is side-axis 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 tube does not exceed 1.5 mm.

[0023] The visual sensing unit includes a high-speed camera and a filter. The filter is embedded in front of the high-speed camera lens; the high-speed camera is used to monitor the arc image, and the monitoring frame rate can be manually adjusted. Specifically, the frame rate of the high-speed camera is not less than 1000 frames / s to meet the shooting requirements.

[0024] A computer processing unit, including high-speed camera image processing software, is used to establish communication between the computer processing unit and the powder feeding unit, so that the powder feeding gas flow rate can be adjusted in real time based on the monitored arc morphology.

[0025] The computer processing unit, the visual sensor unit and the powder delivery unit are all connected by electrical signals, so that the computer processing unit can acquire the pictures taken by the visual sensor unit in real time, and the powder delivery gas flow rate can be adjusted in real time by the computer processing unit. Specifically, the computer is controlled according to the data information analyzed by the image processing unit.

[0026] It should be particularly pointed out that the device is particularly suitable for forming metal matrix composite materials by CMT-WAAM. The method involved in the present invention will be described below by taking the process of forming metal matrix composite materials by CMT-WAAM as an example.

[0027] The second aspect of the present invention provides a method for arc additive manufacturing of composite materials based on visual sensing. The method is based on the CMT-WAAM forming characteristics and includes arc starting, arc burning and arc extinction stages. In the CMT-WAAM arc burning stage, in order to ensure arc stability, the gas flow rate of the powder feeder is controlled to be lower than A max To ensure stable arc burning. In the arc extinction stage, the gas flow rate of the powder feeder is controlled to increase to A0.

[0028] The specific steps of CMT-WAAM forming particle reinforced composite materials are as follows: Step 1: Set the CMT-WAAM forming metal matrix composite process, including wire feeding speed, powder feeding speed, and welding speed.

[0029] Step 2: Position the welding gun so that it is perpendicular to the substrate and maintains an appropriate distance from the substrate; position the high-speed camera so that the camera height is consistent with the welding gun and the shooting angle is perpendicular to the moving path of the powder delivery tube.

[0030] Step 3: Run the visual sensing unit and computer processing unit, run the powder feeding unit, set the gas flow of the powder feeder to A0, run the CMT-WAMM forming program, arc the wire end first, the high-speed camera of the visual sensing unit detects the arc image, transmits it to the computer processing unit, obtains the arc area information through binarization processing, and when the arc area reaches 0.6S max After that, it is considered that CMT-WAAM forming has entered the arc burning stage, and the computer controls the powder feeder gas flow rate to decrease to A max Then CMT-WAAM enters the arc extinguishing stage. When the arc area is reduced to 0.6S max Finally, the computer controls the gas flow rate of the powder feeder to increase to A0. At this point, a cycle of CMT-WAAM forming is completed.

[0031] Furthermore, considering that the diameter of the welding wire is known, the arc area can be calculated by comparing the welding wire diameter with the arc size and converting them in proportion.

[0032] Step 4: CMT-WAAM enters the second forming cycle. As described in step 3, the visual sensor unit transmits the acquired arc image to the computer processing unit, and the computer determines and controls the gas flow of the powder feeder, and the cycle repeats until the forming is completed.

[0033] Furthermore, in step 3, the arc extinction stage is determined by a computer processing unit based on the arc area after binarization.

[0034] Furthermore, the arc area is the area of ​​the white area after the white bright arc is binarized as monitored by the high-speed camera.

[0035] Further, see Figure 2 , when the arc area is greater than 0.6S max , it is determined that CMT-WAAM forming has entered the combustion stage, and the computer controls the powder feeder gas flow rate to reduce to A max Below; 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. max It is the arc area in the arcing stage under specific CMT-WAAM process parameters without the influence of powder feeding gas, and its value changes with the change of CMT-WAAM process parameters. A0 is the preset powder feeding gas flow rate, A max In order to not affect the maximum gas flow rate for stable combustion of the arc, its value is related to the arc tilt factor I.

[0036] Furthermore, the powder feed rate can also be calculated based on the arc tilt factor, see Figure 3 The arc inclination factor I is calculated as follows: take the vertical straight line where the welding wire is located as the boundary, calculate the areas S1 and S2 on the left and right sides of the boundary, S1 / S2 is the arc inclination factor I. It should be pointed out that S1 is the area close to the powder feeding pipe, and S2 is the arc area on the side of the powder feeding boundary close to the formed workpiece.

[0037] Example 1 Take CMT-WAAM particle reinforced metal matrix composites as an example.

[0038] The metal matrix is ​​304L stainless steel, the powder is WC, and the particle size of the WC powder is 17-53 μm.

[0039] The steps of the method for preparing the metal matrix composite material are as follows: Step 1. Set the CMT-WAAM wire feeding speed to 9 m / min, welding speed to 7 mm / s, shielding gas flow rate to 15 L / min, and powder feeding gas flow rate to 8 L / min.

[0040] 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 the camera height is consistent with the welding gun and the shooting angle is perpendicular to the moving path of the welding gun; 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 arc starts at the end of the welding wire, and the high-speed camera detects the arc image and transmits it to the computer processing unit. The arc area information is obtained through binarization processing. When the detected arc area reaches 24 mm 2 After that, it is considered that CMT-WAAM forming enters the arcing stage, and the computer controls the powder feeder gas flow rate to be reduced to below 2 L / min. Then CMT-WAAM forming enters the arcing stage. When the arc area is reduced to 24 mm 2 After that, the computer controls the gas flow rate of the powder feeder to increase to 8 L / min. At this point, one cycle of CMT-WAAM forming is completed.

[0041] Step 4: CMT-WAAM enters the second forming cycle. As described in step 3, the visual sensor unit transmits the acquired arc image to the computer processing unit, and the computer determines and controls the gas flow of the powder feeder, and the cycle repeats until the forming is completed.

[0042] This embodiment adopts CMT-WAAM technology, and there is an arc extinction stage in its forming process. This embodiment uses the gap when the arc is extinguished to transport WC powder to the molten pool, and there is no problem of powder feeding airflow disturbing the arc.

[0043] Example 2 Take MIG-WAAM particle reinforced metal matrix composites as an example.

[0044] The metal matrix is ​​304L stainless steel, the powder is WC, and the particle size of the WC powder is 17-53 μm.

[0045] The steps of the method for preparing the metal matrix composite material are as follows: Step 1: Set the MIG-WAAM wire feeding speed to 7 m / min, welding speed to 5 mm / s, shielding gas flow rate to 15 L / min, and powder feeding gas flow rate to 8 L / min; 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 the camera height is consistent with the welding gun and the shooting angle is perpendicular to the moving path of the welding gun; 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, deliver WC powder at a gas flow rate of 8 L / min, and then immediately run the CMT-WAMM forming program. The arc starts at the end of the welding wire. The high-speed camera detects the arc image and confirms the position of the welding wire, which is transmitted to the computer processing unit. After binarization, the arc inclination factor I is judged. The basis for judging the arc inclination is as follows: Taking the straight line where the welding wire is located as the boundary, the areas S1 and S2 on the left and right sides of the boundary are measured, 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 airflow until the arc inclination factor reaches 0.6, and the computer controls the powder feeding gas flow to remain unchanged.

[0046] This embodiment uses MIG-WAAM technology, and there is a problem of powder feeding airflow disturbing the arc during its forming process. This embodiment uses a visual sensor unit and a computer processing unit to judge the arc inclination, and can efficiently obtain the bypass powder feeding gas flow that can ensure the stability of the arc shape under specific MIG-WAAM process parameters. 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.

[0047] Based on the above analysis, it can be seen that in the CMT-WAAM manufacturing process, the method of the present invention uses a high-speed camera to determine the change of the arc area, and uses the gap when the arc is extinguished to complete the transportation of the reinforced particles into the molten pool, thereby avoiding the influence of the powder conveying airflow on the arc burning, and can greatly improve the stability of the CMT-WAAM particle-reinforced metal matrix composite forming process.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, the first feature "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features not being in direct contact but being in contact through another feature between them.

[0050] In the description of the present invention, “on”, “over” and “above” a first feature from a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0051] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", 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 present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0053] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for arc additive manufacturing of composite materials based on visual sensing, characterized in that: The method comprises the following steps: S1, setting cold metal arc additive manufacturing process parameters; S2, setting the welding gun position and high-speed camera height, with the camera focusing on the welding gun and the deposited layer; S3, during the cold metal arc additive manufacturing process, a high-speed camera takes an arc image. When the arc area is larger than the 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; S4, repeat S3 until the molding is completed.

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

3. The method for arc additive manufacturing of composite materials based on visual sensing according to claim 1, characterized in that: 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 when there is no powder feeding gas.

4. The method for arc additive manufacturing of composite materials based on visual sensing according to claim 1, characterized in that: In S3, it is determined whether the arc inclination factor is less than 0.

6. If the arc inclination factor is less than 0.6, the powder feeder airflow is reduced until the arc inclination factor reaches 0.6 and the powder feeder airflow remains unchanged.

5. The method for arc additive manufacturing of composite materials based on visual sensing according to claim 4, characterized in that: The arc inclination factor is the ratio S1 / S2 of the arc areas on both sides of the powder feeding boundary, the powder feeding boundary is the vertical direction of the welding wire, S1 is the arc area on the side of the powder feeding boundary close to the powder feeding pipe, and S2 is the arc area on the side of the powder feeding boundary close to the formed workpiece.

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

7. The device for arc additive manufacturing of composite materials based on visual sensing according to claim 1, characterized in that: In S3, when the high-speed camera takes the arc image, the shooting angle is perpendicular to the moving path of the powder delivery tube.

8. A device for arc additive manufacturing of composite materials based on visual sensing for implementing the method of claim 1, characterized in that: It includes a molding unit, a powder feeding unit, a visual sensing unit and a computer processing unit; The powder feeding unit is used to feed powder material to the molding unit, and the molding unit manufactures the workpiece by a cold metal arc additive manufacturing process; The powder delivery unit is connected to the computer processing unit by electrical signals, and the visual sensing unit is connected to the computer processing unit by electrical signals.

9. The device for arc additive manufacturing of composite materials based on visual sensing according to claim 8, characterized in that: The visual sensing unit comprises a high-speed camera and a filter, wherein the filter is arranged in front of the high-speed camera lens.

10. The device for arc additive manufacturing of composite materials based on visual sensing according to claim 8, characterized in that: 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 to display the image processed by the high-speed camera, and the powder feeding module is used to control the powder feeding speed of the powder feeding unit.

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