Special device and method for variable-section arc additive based on laser displacement sensor

Abstract

The present invention discloses a special device and method for variable-section arc additive based on a laser displacement sensor, and relates to the technical field of additive equipment. The device consists of two parts: a software system and a hardware system. The software system mainly includes off-line programming software for model slicing, path planning and model prediction, and an intelligent control system for sensor signal processing and output; the hardware system mainly includes a laser displacement sensor and an arc additive device. The present invention solves the problem of metal dripping of thin-walled structures and the problem of uneven layer thickness of the overall component during the arc additive process of variable-section components. The device is easy to use and has diversified functions, and can improve the forming accuracy and mechanical properties of variable-section components.

Description

Technical Field

[0001] The present invention relates to the technical field of additive equipment, and in particular to a special device for variable-section arc additive and a method for using the same. Background Art

[0002] Electric Arc Additive Manufacturing (WAAM) is an additive method that uses electric arc as the energy beam to melt metal wire and then use layer-by-layer stacking to manufacture dense metal solid components. It has the characteristics of high material utilization, high molding efficiency, no restrictions on the size of molded parts, and low cost. It can realize the structural and digital manufacturing of the entire component. It is widely used in many fields such as HK aerospace and marine engineering.

[0003] Compared with traditional arc additive manufacturing technology, cold metal transfer technology greatly reduces the heat input in the additive process due to its new droplet separation method, which is beneficial to improving the forming accuracy and mechanical properties of components.

[0004] However, in the process of arc additive, due to its layer-by-layer accumulation and liquid droplet transition mode, a large amount of heat accumulation will still be generated during the additive process, resulting in overheating of the molten pool and difficulty in heat dissipation. This affects the forming effect of the overall component. Especially for variable-section components, since the length of each path during processing is different, the cooling time is also different. In thin-walled structures, it is easy for the previous path to not cool down and the next path to be stacked up, resulting in serious dripping in the thin wall and large dimensional deviation, resulting in the overall component with low sides and high middle appearance, which cannot achieve the required dimensional accuracy and mechanical properties of the component. At present, the process parameters and cooling time in the printing process are mainly controlled by the technicians' own experience. There is no special hardware and software equipment to monitor and adjust it. The control of dimensional accuracy is greatly affected by subjective factors, and it often reacts only after dripping occurs, which has a large lag. Summary of the invention

[0005] The purpose of the present invention is to provide a special device for variable-section arc additive manufacturing based on a laser displacement sensor to solve the problem of material dripping at the thin-walled parts of existing CMT arc additive variable-section components and the problem of insufficient forming accuracy of the overall components.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A special device for variable-section arc additive based on laser displacement sensor, which is special in that:

[0008] Including offline programming system, intelligent control system, laser displacement sensor, and additive manufacturing hardware system.

[0009] The offline programming system consists of three parts: three-dimensional modeling software, slicing and layering software, and intelligent simulation software. The three-dimensional modeling software is used to establish and optimize the basic model of the parts. The slicing and layering software slices the model and obtains the specific walking path of each layer under the set parameters such as layer thickness, path filling form, and filling speed, and displays its path through simulation. The intelligent simulation software simulates the arc additive process under the influence of external humidity, protective gas flow, etc. based on the slicing and layering path and results, providing a basis for model optimization, parameter correction, re-layering, etc., to achieve single-level optimization. The above three software functions are integrated into a computer system, connected to the robot control cabinet through an external port, and the operation sequence is "three-dimensional modeling-slicing and layering-intelligent simulation".

[0010] The laser displacement sensor includes a laser generating device and a signal conversion device. The laser generator is controlled by a manual switch. When emitting light, it scans the components in the entire arc additive process and transmits it to the signal conversion device and converts it into a recognizable data signal. The upper end of the signal conversion device is connected to the signal receiver of the intelligent control system. There are two laser displacement sensors, one is placed in the front to scan the overall front profile and overall height change of the arc additive part, and the other is placed on the right to scan the single-track profile and height change of the arc additive part. The laser displacement sensor is fixed to the tooling platform through a tripod.

[0011] The intelligent control system includes a signal receiver, a signal processor, an external display, and an intelligent analysis system. When the signal receiver receives the signals output by the two laser displacement sensors, the signal processor converts them into data signals that can be recognized by the analysis system and transmits them to the analysis system. The intelligent analysis system integrates the two data signals to form a model of the actual additive situation, and after combining them with the layered model, the error value is transmitted to the offline programming system for real-time modification of parameters including the number of layers and speed, thereby achieving double optimization.

[0012] The additive manufacturing hardware system includes a robot system and an arc additive device. In the robot system, the robot teach pendant is connected to the robot control cabinet for inputting process parameters and additive paths. The teach pendant is provided with automatic and manual modes for controlling the movement of the robot body, and is provided with an emergency stop button. The robot body is connected to the robot control cabinet. The arc additive device includes an additive head, a CMT welder, a wire feeder, and an air supply device. The additive head is fixed on the robot body and connected to the CMT welder. The wire feeder is placed above the CMT welder and connected to the CMT welder to control the wire retraction. The air supply device consists of a gas cylinder, an air pressure valve, an air supply pipe, and a clamping device. The air supply pipe and the wire feeding mechanism are both fixed in the middle of the additive head, and the air pressure valve can adjust the air flow.

[0013] Furthermore, the CMT welding machine can be externally connected to a real-time voltage monitoring device and a current converter, which can be used to output the current and voltage signals in the additive process in real time.

[0014] Furthermore, the arc additive device may be equipped with a temperature sensor to collect temperature change and heat accumulation data during the additive process.

[0015] Furthermore, a knob is provided behind the laser displacement sensor to adjust the laser intensity to suit the actual external environment.

[0016] Furthermore, the laser displacement sensor can be interchanged in front-to-back position or left-to-right position according to actual needs, and its number can also be increased.

[0017] Furthermore, the multiple system software are connected to each other via external ports and data cables.

[0018] Furthermore, the external display of the intelligent control system can synchronously display the scanning results of the laser displacement sensor to form real-time three-dimensional imaging of the additive process.

[0019] Another object of the present invention is to provide a method for using a variable-section arc additive device based on a laser displacement sensor to solve the problem of material dripping at the thin wall of the existing CMT arc additive variable-section component and the problem of insufficient forming accuracy of the overall component. The method includes the following steps:

[0020] Step 1: Use 3D modeling software to create a CAD 3D model of the required variable-section component.

[0021] Step 2: Import the 3D model of the variable-section component into the layered slicing software, set the required single-layer thickness, robot travel speed, inter-layer waiting time, overlap rate and other parameters, and generate the layered model and additive path of the variable-section component.

[0022] Step 3: Import the layered model into the intelligent simulation software, and pre-simulate the entire additive process of the variable cross-section component according to the path planning. If the simulation results are good, output the process parameters and path planning to the robot control system. If the simulation results do not meet the requirements, reset the process parameters and path.

[0023] Step 4: Open the robot control cabinet and teach pendant, and retrieve the generated parameter and path files. Start the CMT welder, wire feeder, and gas supply device. Add a command line in the robot teach pendant to control the operation sequence of the instruments: CMT welder-gas supply device-wire feeder-robot body.

[0024] Step 5: Turn on the laser displacement sensor and intelligent analysis system, and the robot starts working. The laser displacement sensor records the layer height, layer width, etc. during the additive process, and forms an output signal to be transmitted to the intelligent analysis system. A real-time 3D rendering is presented on the external display, and compared with the pre-simulation model, the thin wall dripping and the overall layer thickness are monitored. When deviations occur, the process parameters of the next layer are adjusted in time to ensure the flatness of the entire additive part and the uniformity of the overall thickness. After completing the additive process, the corresponding equipment is turned off in sequence.

[0025] Beneficial effects of the present invention:

[0026] (1) Compared with common arc additive manufacturing, the present invention provides a special device for arc additive manufacturing of variable cross-section components. It uses advanced laser displacement sensors to record layer height related data during the entire additive process and conduct real-time feedback and adjustment. This can solve the problems of material dripping at thin-walled parts and uneven layer thickness of the entire component during the additive manufacturing process of variable cross-section components.

[0027] (2) The present invention provides a special device for arc additive manufacturing of variable-section components. Based on recording the layer height and layer width of the component, it can present a specific real-time three-dimensional rendering on an external display, which allows a more intuitive understanding of the specific additive process of the part and helps to more clearly understand the impact of parameter changes in the additive process on the actual effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is an overall device diagram provided by an embodiment of the present invention;

[0029] Figure 2 It is a three-dimensional diagram of a variable cross section provided by an embodiment of the present invention;

[0030] Figure 3 It is a schematic diagram of an interface path provided by an embodiment of the present invention.

[0031] In the figure:

[0032] 1-variable cross-section parts; 2-substrate; 3-robot system; 4-offline programming system, 5-intelligent control system; 6-data connection line; 7-first laser displacement sensor; 8-tripod; 9-arc additive device; 10-second laser displacement sensor; 11-tooling platform DETAILED DESCRIPTION

[0033] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" 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 an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In the description of this embodiment, the terms "front", "rear", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0036] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0037] like Figure 1 As shown, the special device for arc additive of variable-section components is provided with a first laser displacement sensor 7 and a second laser displacement sensor 10, the arc additive device 9 and the robot system 3 constitute an additive hardware device, the off-line programming system 4 composed of three-dimensional modeling software, layered slicing software and simulation analysis software and the intelligent control system 5 constitute a control device, and the base plate 2 and the tooling platform 11 constitute an integral fixing device.

[0038] In this embodiment, the offline programming system 4, the analysis and feedback system 5, the robot system 3, the laser displacement sensors 7, 10 and the arc material addition device 9 are first connected by the data connection line 6, and each system is turned on to confirm that the connection is good. In this embodiment, the offline programming system 4 used includes three parts: 3D modeling software, slicing and layering software and intelligent simulation software. The 3D modeling software is used to establish the model of the variable cross-section component, such as Figure 2As shown, the XY plane is selected as the drawing plane, with +X, +Y, and +Z as the positive directions, and the substrate model and its size are drawn based on the measurement results. Then, the upper surface of the substrate model is used as the bottom surface, and the actual part size is used as the standard to draw the arc additive variable cross-section component model, and obtain the STL file of the three-dimensional model. The width of the components at both ends and the center is different, and the transition part is generally transitioned with an arc. The slicing and layering software reads the three-dimensional STL file of the variable cross-section component model, slices it in a plane, generates the "exterior wall" outline and the internal filling path, and simulates the specific walking path and walking process on the external display. The "exterior wall" here refers to the outer contour of the metal. Specifically, in the process of plane slicing and path generation, it is necessary to set relevant arc additive process parameters, including process library, scanning speed, wire feeding speed, single layer height, maximum number of printing layers, cooling time, number of exterior wall layers, filling spacing, etc. The process library is mainly selected according to the type and thickness of the welding wire material used. The wire feeding speed and scanning speed affect the width, height and quality of the single-layer weld. The current voltage and wire feeding speed are set as an integrated parameter, and no separate adjustment is required. The specific values ​​need to be determined by searching for the corresponding additive process. The intelligent simulation software simulates the manufacturing of the slice model in the actual additive environment, evaluates the rationality and practicality of the current parameters, and feeds back to the layered slicing software for parameter correction and path modification to achieve the first optimization. Specifically, in the process of simulated manufacturing, the values ​​of parameters that have a greater impact on the arc additive process, including ambient humidity, ambient temperature, and shielding gas flow, can be manually set to improve the simulation accuracy. At the same time, the component printing accuracy value can be set. If it is higher than this value, it will be output to the robot system, and if it is lower than this value, it will be returned to the slicing and layering software.

[0039] In this embodiment, the additive manufacturing hardware system includes a robot system 3 and an arc additive device 9. The arc additive device 9 includes an additive head, a CMT welder, a wire feeder, and a gas supply device. The additive head is fixed on the robot body and operates synchronously with the robot. The robot system 3 includes three parts: the robot body, the robot control cabinet, and the teaching pendant. The robot teaching pendant is connected to the offline programming software through the network and is used to stably receive the code file. After receiving the start command, the robot works in coordination with the arc additive device 9 to complete the entire additive process according to the specified path under the appropriate current voltage and wire feeding speed until a stop command is received. Specifically, after the robot teaching pendant receives the code file, it is displayed on the teaching pendant screen. After confirming that it is correct, the manual mode needs to be adjusted to the automatic mode to ensure that the process continues. At the same time, the robot needs to use the three-point method to calibrate the zero-point coordinates to ensure that the actual working coordinates of the robot are consistent with the positions in the layered slicing software. Before fixing the laser displacement sensor, the robot is run without turning on the CMT welder. After confirming that its working path and related positions are correct, the position of the substrate 10 is adjusted to make the parts in the appropriate specific printing position, and the substrate 10 is fixed with a fixture to ensure the relative position of the fixture and the robot is safe. Then the welder is turned on to complete the entire additive process. An emergency stop button is provided on the robot teaching pendant.

[0040] In this embodiment, two laser displacement sensors are provided, namely, a first laser displacement sensor 7 and a second laser displacement sensor 10, both of which are fixed on the tooling platform through a tripod and connected to the intelligent analysis software through a data cable. The laser displacement sensor adjusts the lens up and down and left and right through the rotating arm on the tripod. It is equipped with a red light spotlight to facilitate the calibration of the laser displacement sensor position. In addition, the intelligent analysis system connected to the laser displacement sensor can display the shooting position in real time. After turning off the red light and turning on the laser, adjust the knob behind the sensor to control the laser intensity, and fix its position when the substrate can be clearly seen. The first laser displacement sensor is placed on the front of the variable cross-section component to monitor its overall profile and overall height change during the additive process. The second laser displacement sensor is placed on the right side of the variable cross-section component to monitor its single-channel profile and height change. The distance between the sensor and the workpiece is mainly adjusted according to the size of the workpiece to ensure that the overall additive process of the entire workpiece can be seen. The specific number and specific position can be appropriately adjusted according to the experimental conditions and experimental requirements.

[0041] In this embodiment, the intelligent control system 5 includes a signal receiver, a signal processor, an external display, and an intelligent analysis system. After the signal receiver receives the signal from the laser displacement sensor, the signal processor converts the transmission signals of the two laser displacement sensors into the analysis system in real time. The analysis system integrates the transmission signals of the two laser displacement sensors in real time to improve the accuracy of the actual model. At the same time, the comparison process between the actual variable cross-section component and the initial model is presented through the external display, and the relevant error value is calculated, which is then transmitted to the offline programming system for secondary optimization of process parameters including layer height, scanning speed, etc.

[0042] Optionally, a temperature sensor may be added to the arc additive device 9 to collect temperature changes and heat accumulation during the additive process.

[0043] In summary, the variable-section arc additive device based on laser displacement sensors provided by the present invention has a simple overall structure and strong versatility. Compared with ordinary arc additives, advanced laser displacement sensors are used to record the layer height related data in the entire additive process, and combined with the simulation analysis software before additives and the intelligent analysis system after additives, real-time feedback and adjustment in the additive process are performed, which realizes multiple optimizations of the overall additive process, and can well solve the problems of material dripping down at thin-walled parts and uneven layer thickness of the overall component during the additive process of variable-section components. At the same time, by connecting the intelligent analysis system to an external display, it is possible to present a real-time three-dimensional rendering of the variable-section component during the specific additive process, which can more intuitively understand the specific additive process of the component and more clearly understand the impact of parameter changes in the additive process on the actual effect.

[0044] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A variable-section arc additive device based on a laser displacement sensor, characterized in that: The variable-section arc additive manufacturing device includes an additive manufacturing hardware system, a laser displacement sensor, an offline programming system, and an intelligent control system; The additive manufacturing hardware system comprises a robot system (3) and an arc additive device (9); there are two laser displacement sensors, a first laser displacement sensor (7) is placed on the front of the component, and a second laser displacement sensor (10) is placed on the right side of the component, fixed by a tripod, and is mainly used to monitor the overall and single-channel contour morphology and height changes during the additive process; The offline programming system (4) includes three parts: three-dimensional modeling software, slicing and layering software, and intelligent simulation software. The three-dimensional modeling software and the slicing and layering software are mainly used for establishing a three-dimensional model of the workpiece to be processed and path planning. The intelligent simulation software simulates the external environment parameters in real time, performs intelligent simulation before the actual additive process, and predicts the actual printing effect and printing error, so as to verify the rationality of the additive manufacturing plan planned by the offline programming system (4), and optimizes the slicing process and process parameters through result output and error feedback. The intelligent simulation software is integrated with the three-dimensional modeling software and the slicing and layering software in a computer system, which is connected to the robot control cabinet; the intelligent control system (5) includes four parts: a signal receiver, a signal processor, an external display, and an intelligent analysis system. The signal receiver and the signal processor are responsible for receiving and collating information, establishing an actual additive model, and presenting it clearly and intuitively through the external display. The intelligent analysis system compares and analyzes the actual model with the initial model to achieve parameter optimization; The offline programming system (4) is combined with the intelligent control system (5) to achieve dual optimization of the variable cross-section component before and during arc material addition; The offline programming system (4) is provided with an environmental parameter window, which can manually input parameters including environmental temperature, environmental humidity, and protective gas flow rate under the condition of detecting the external environment, so as to realize a simulated printing process in a substantially consistent environment with the real additive manufacturing environment through the intelligent simulation software, and through the setting of relevant thresholds, the layer height, overall forming size and accuracy, side wall roughness, and fusion effect are evaluated layer by layer, so as to provide a corresponding basis for parameter correction and feedback to the slicing and layering software, so as to optimize the additive manufacturing path and process parameter design, that is, to realize the first optimization; The intelligent control system (5) realizes real-time monitoring of the additive process by receiving the signal of the laser displacement sensor during the specific arc additive process, compares the overall morphology and related parameters of the actual printed part with the initial slice model before printing in real time, detects the uniformity of the layer thickness of the overall variable cross-section component and the dripping condition at the thin wall, calculates its deviation and compares it with the set error value; when the error exceeds the threshold, the relevant signal is transmitted to the intelligent analysis system, and the intelligent analysis system analyzes the layer thickness by comparing the difference between the two layers, thereby modifying the process parameters related to the wire feeding speed and the cooling time, and re-feeds back to the additive equipment through the downlink signal, so as to immediately make real-time adjustments to the process parameters, control the wall thickness and the forming accuracy to return to the pre-standard, ensure the overall printing effect, and achieve the second optimization; The laser displacement sensor is provided with a knob at the rear side for adjusting the laser intensity; the arc additive device (9) can be externally connected to a voltage real-time monitoring device and a current converter for real-time output of current and voltage signals during the additive process, and a temperature sensor can be additionally provided for collecting temperature changes and heat accumulation data during the additive process; the intelligent control system (5) is connected to an external display and can present a real-time three-dimensional effect diagram of a variable cross-section component during a specific additive process by integrating and analyzing the data signals of the two laser displacement sensors, thereby more intuitively and clearly reflecting the arc additive process and the influence of parameters.

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