Research On The Mechanism Of Water Jet Incremental Sheet Metal Forming

As the rapid movement of the market environment, the requirement of consumers is becoming more and more principle, individual, and various. The updating of the products is more and more quickly, the customization of the product fashion is growing up. So all of these need manufacturing continue to open out new product to meet people's need. And these new products must be made quickly so that they can occupy the market quickly. As the long period of the provision and high cost of the conventional method using mold, it can not meet the need of the market, such as variety and small batch. So many flexible productions appear recently, such as peen forming, numeral incremental forming, multi-point forming, laser thermal stress forming, laser shock forming and so on. All of these techniques need the support of CNC. They can shape the sheet without die, so they have high flexibility. The overcome the disadvantage of die, saving the cost and period of the production, especially adapt to the research of new products and small production.Besides all of these method above on, Water Jet Incremental Sheet Metal Forming (WJISMF) is a new method of die-less. It bases on the computer technology, numerical control technology, material forming technology, and water jet technology. It adopt the idea of the delamination produce to scatter a complex 3D shape to many 2D layers along Z axis, and then the water jet machine partially on these layers. The water come through the high pressure pump and pass through the muzzle to become high pressure water jet, ejecting on the material sheet, when the pressure reach to the degree, the sheet will distortion, under the control of the CNC, the jet will move along the fixed path, so one layer is made, after that the water jet descend along the Z axis to shape next one, cycle as these till to the end.The automobile industry is thriving, the sell of the car is successively climbing, so many new products come out every year. The main job of the new product research is design of the bodywork, it needs pass many programs before beingproduced, the trial-manufacture need much time, money and work, so the cost and period of the new product research is very high. WJISMF can shape any figure, no matter how complicated the shape, so it can provide an efficient approach of manufacturing the bestrow products. In addition, for the variety and small batch of the product of the airplane and secondary planet and the other thin shell product, it also has huge economic value. The shape of the product manufactured in this way can be more complicated than the conventional. It can bring a revolutionary influence to the sheet forming, and also renovate the conception of the sheet product design, so the idea of the new product design will gain more big exertion. It have wide application foreground.As far as soon, many institutions are researching this technique. Among these researches, there are little researches about mechanism of the technique, so that although the technique begins to be applied in the production, there are no literatures expatiating the technique on theory. So the main job of us is to explore the mechanism of the technique based on the theory of material forming and high pressure water jet for the farther research about this technique. The principle content involves the following several respect:(1) The application of high pressure water jet in WJISMFIn WJISMF, high pressure water jet plays an important part as the forming tool. The sheet forming is mainly depends on the pressure exerted on the surface of the sheet by the water jet. Now the water jet has been used in many fields such as removing rust on the ship, industry cleaning, maintaining bridge, coal bed exploitation, assistant dig, road destroy and so on. But it is the first time to apply the water jet in the forming field. Comparison with other applications, sheet forming needs precision dimension and good quality of the surface. So we must analyse and control the parameters correlate to the water jet. We research the account measure about the force of the water jet, and research the range of the working pressure of the water jet to make the quality of the surface be good, but not be penetrated or corroded. In addition, for gaining the best distance between water jet and sheet and the best working range, we make research about thedistance and the length of the water jet, whose pressure is in the range between 10MPa and 50MPa by examination.(2) The research about sheet forming mechanismTo make the sheet form according to the require is tenet of the technique, stress and strain are the parameters of the essence of the forming. So we research the changing rule and characteristic of the stress and strain in the course of the forming to master the forming course. And then we research the account measure about the forming force base on the theory correlate to the material forming. Combine the account measure about the forming force with the account measure about the force of the water jet to deduct to the relationship between water jet pressure and the parameters of the forming to give basis to the control of the pressure.(3) Simulation and validationFor validating the conclusions gained from the research, we make a simulation by using the emulator. And then we make a comparison between the result and conclusion to validate the rationality of the conclusion.