The Process Study And Path Planning Of High-pressure Water Jet Incremental Forming

This exploratory paper aims to introduce a high-speed Water Jet (WJ) as a tool for die-less Incremental Sheet Metal Forming (ISMF).It use a high-speed Water Jet (WJ) as a tool instead of the rigid tool. And the tool to work-piece surface interface is liquid-solid .This fact brings many ad vantages such as low friction between the tool and the work-piece and no need for lubrication during the forming process.Additionally, the loads at the tool to work piece interface surface are more evenly distributed when compared to ISMF with a rigid tool. However, in the case of Water Jet Incremental Sheet Metal Forming (WJISMF) the forming time, energy efficiency and forming accuracy are rather poor compared to ISMF with a rigid tool. All of these need to be improved.Water Jet Incremental Sheet Metal Forming (WJISMF) was improved by Iseki in 2001 and Jurisevic in 2003. It's at the initial stage now, so its deformation and destroy theory is not perfect, the forming devices are rather crude, most of them are modified by other equipment, so the forming accuracy is also poor. So far, the domestic research on the technology doesn't fall behind with the foreign research, so we must catch up, occupied the commanding heights of the technology.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 Water Jet incremental sheet metal forming process is a flexible forming process without dedicated forming dies. Thus, its forming period is short and products can be quickly renovated. This process is very suitable for small-lot, varied and complex sheet metal products.In this paper, the forming principle of the Water Jet incremental sheet metal forming process is researched. The deformation law is obtained from the experiments performed on the Water Jet incremental sheet metal forming machine. The stress, strain and deformation force in the deformation process are analysed in detail and formulas are obtained. The key process parameters in the Water Jet incremental sheet metal forming process consist of the water stress, forming half-apex angleα, ironing ratio, amount of lateral feed, Target distance, amount of Vertical feed, feed speed of the forming tool, and so on. In this paper, the effect of all the process parameters on the deformation process and how to choose suitable process parameters are researched, which is an important condition of success in the Water Jet incremental sheet metal forming process. The research on the forming principle provides a powerful rationale for the practical production.In this article, the author used numerical analysis method, established a fluid-solid interaction control equation taking solid and fluid as a unified mathematical model. Then we calculated the two-dimensional fluid-solid interaction field, and obtained the deformation of the whole structure and the distribution of the field. In our calculation, ALE description is used in fluid domain in which the mesh point continuously renew with the motion of free surface of liquid or the movement of the contact surface between the structure and liquid.In this paper, a water jet incremental sheet metal forming process is presented according to the above-mentioned researches. The forming experiments of some simple parts have been made, and good results have been achieved.This paper also made the path planning for some hard machining pieces , such as pieces have less forming half-apex angle than the limits of forming half-apex angle, pieces of straight-walled, spheroidal pieces, nested loop pieces and so on. This paper also explored that using the sprinklers Multi-point and the trajectory of reverse ring to enhance the forming accuracy. Using the Planned paths can extend the forming range of the water jet incremental sheet metal forming, implement the forming of the complex pieces, so that the water jet incremental forming technology tends to be more practical.