| Welding wire or powder is heated and melted by plasma arc with high energy density,and then the melted welding material is stacked layer by layer to deposit the designed component,which is called plasma arc additive manufacturing technology.At present,this method is mainly applied to the components with large size and complex morphology.Due to the high energy density and concentration of plasma arc,the deposition process is easy to lead to the appearance of molten pool overflow phenomenon.Therefore,how to reduce the droplet overflow and reduce the probability of deposition layer collapse is an urgent problem for plasma arc additive manufacturing.After the droplet overflow,the morphology of additive manufacturing layer may lead to a large difference between the subsequent stacking process and the original plan,and the morphology and size of the workpiece obtained are quite different from the original design model.Therefore,improving the accuracy of additive manufacturing coating is another problem to be solved in this paper.In this paper,firstly,a magnetron plasma arc sensor is designed to reduce the phenomenon of molten pool overflow caused by the accumulation of heat in the cladding layer.Then,a magnetron plasma arc additive manufacturing system is established to detect the forming information of single pass and multi-layer plasma arc additive manufacturing and develop adaptive control.(1)In this paper,the magnetron plasma arc welding gun is designed based on the force analysis of swing plasma arc and molten pool,and the magnetron swing arc method and plasma arc additive manufacturing method;By controlling the arc swing on the deposited layer of additive manufacturing by magnetic control,the accumulated heat on the surface of the deposited layer is effectively reduced,and the solidification time of liquid metal in the molten pool is reduced.Thus,the phenomenon of molten pool overflow caused by heat accumulation in the manufacturing process of plasma arc additive is reduced.(2)In this paper,the design and research of the method for detecting the morphology of the coating in the manufacturing process of magnetron plasma arc additive are carried out.By establishing the mathematical model of arc length and various parameters,the parameters for detecting the morphology and size of the coating are obtained,which are mainly based on the input of the deposition current,deposition voltage,excitation current frequency and torch height,The data of welding current,welding voltage,exciting current frequency,welding torch height and additive manufacturing layer morphology and size were obtained.(3)next the first mock exam is carried out on the experimental data.The prediction model of the height and width of the BP coating is successfully constructed.The training model is trained and verified,and the 4-13-2 neural network structure of BP is established.Through the training of neural network model,the prediction of cladding morphology and size in additive manufacturing process is realized.(4)According to the characteristics of magnetron plasma arc additive manufacturing technology,a deposition size controller for magnetron plasma arc additive manufacturing is designed.Through the controller,the morphology and size of the deposition layer for additive manufacturing can be adjusted in real time,and then the precise forming of the deposition layer for plasma arc additive manufacturing can be realized.(5)Finally,the relevant components are manufactured by the method described in this paper on the platform built in this paper.The experimental results show that the components to be manufactured have regular morphology,high forming accuracy and no obvious defects.Therefore,the shape detection and adaptive control system designed in this paper can improve the forming accuracy of plasma arc additive manufacturing. |
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