Study Of The Manufacturing For Smart Metal Structure Based On Welding Prototyping Technology

Smart material structure has the potential to be used in many fields, including military affairs, aviation and spaceflight, automobile and medicine, so smart material structure is a research hotspot and a trend of development. Now there are many achievements in design and manufacture of composite material parts. However, there are difficulties of sensor embedding and metal structure forming. In this paper, a method is presented for manufacturing the smart metal structure, which is based on the welding prototyping technology.The welding prototyping parts are made of pure welds; they have the characterics of high strength, high density and low cost. The welding prototyping and its thermal process have been studied in this paper, according to the characteristics of GTAW welding and the requirements of the FBG smart structure. The real-time control of welding process has been realized. At the same time, the metal coated FBG sensor was embedded in the metal structure successuffly during the prototyping process. The main work is listed below:1. The welding prototyping system of smart metal structure manufacturing has been established. The position of welding torch can be real-time controlled; the welding parameters can be adjusted quickly according to the requirements of welding prototyping; arc striking, extinguishing and wire feeding can be controlled with the help of computer; the optic fiber sensor can be protected.2. Based on the studies of welding prototyping process, the effects of welding parameters has been analysed. There are three controllable factors in the process, which are welding current, welding speed and wire feed rate. The quadratic regression revolution design has been applied and a model based on the relation among these parameters and weld geometry size has been established. The effects of welding parameters on the weld geometry have been analysed. Based on the analysis of general metal components, three kinds of basic structure were obtained, which are single-channel multi-layer, single-layer multi-channel and inclination, respectively. The controling parameters have been obtained by using a combination method of experiment and modeling. The controllable forming on basic structure is achieved.3.The temperature distribution of forming process was obtained using the finite element analysis method. And the effects of different forming trajectories on the temperature distribution were discussed. The microstructure of different position for the metal part was obtained using the standard metallography method. Results show, the surface structures was acicular martensite and bainite; the internal structure was the equiaxed grain similar to normalizing organization. Thus, the hardness shows the decreased characteric from the surface layer to the internal layer. The tensile test shows that the mechanical properties of prototyping metal parts in the direction of the welds reach the value of wire deposited metal.4. The functional relation have been established based on the study of the the welding voltage, welding current and arc length. A fuzzy control system for the weld size control is established. The weld reinforcement can be indirectly collected by measuring the welding voltage. And the welding voltage was used as the feedback quantity to adjust the welding parameters in time. Results show that the welding parameters can be adjusted and controlled well. Thus the accuracy of the metal structure can be improved obviously.5.A sub-forming hybrid milling method for the metal structure manufacturing is presented in this paper, which is based on the thermal (welding) and cold (milling) processing thechnology. The surface accuracy of the metal part was much higher than the direct welding forming; and the machining allowance was decreased. A variety of well forming metal parts was acquired using this method.6. According to the experimental and simulation analysis of the FBG sensor embeding process, the distance of the sensor and the weld pool should be more than 5mm. A surface plated FBG sensor was embedded in a piece of metal by induction brazing method. Then the metal block was embedded in the metal structure during the welding prototyping process. A smart metal structure with the function of self temperature sensing is then obtained.