Papers by Keyword: Bending Forming

Abstract: To study the bending characteristics of copper alloy thin plate by single pulse laser, the thermal mechanical coupling model of pulsed laser forming (PLF) was established; the dynamic change and steady distribution for the fields of temperature, stress& strain and displacement were analyzed. The results show n that during the pulse laser heating stage, the temperature gradient along the thickness direction is far less than that of the heat affected zone; due to the constraints of materials around the heating field, the compressive stress and negative strain are appeared, the cantilever end of sample produces warping deformations; in the cooling stage, the temperature of top and bottom surface material drops rapidly, the sample is with a negative bending and reduced deformation. This is related to the transferring of the stress change and the recovery of part of the elastic deformation in heating area.

Abstract: By FEA method, the bending of the copper alloy thin-plates by continuous laser forming (CLF) and pulse laser forming (PLF) was studied. Based on the analysis of dynamic change and steady distribution for the fields of temperature, stress/strain and displacement, the forming mechanism and rule of copper alloy by different laser modes were revealed. The whole deformation of PLF was the additive effect of all impulse action, while CLF mainly was the result of thermal stress. To get the same deformation, laser pulse energy is about 6 times of the continuous laser，CLF is suitable for larger deformation demands, and PLF is more seemly for micro-forming.

Abstract: In this paper, on the basis of bending forming force and deformation analysis for a stainless steel part in a precision instrument, the combination mould having filling and support function is designed for the part with large size, ultra thin-walled and non-closed cross section structure characteristics. Combined with the forming process, the technological measures are proposed to eliminate the bending forming deformation by using the way of incremental forming control and the gap control between mould and part. And the forming process and the reliability are verified by the practical application.

Abstract: A new forming method of honeycomb semi-cell structures was proposed by analyzing the defects of finished products processed by traditional roll forming method. Using ANSYS/LS-DYNA, a numerical analysis of its forming process was set up. A new forming equipment has been developed to conduct experiments. The results of experimental and numerical analysis show that the new forming method of the honeycomb semi-cell structures is feasible and superior.

Abstract: In this article, a FEM model of high-frequency induction bending with gravity is established and with which the heated temperature, stress, deformation, residual stress and bending angle after cooling, etc are studied on different thickness ship plate. The results show that the steel plate can be heated to 860 above the austenitic temperature. Heating temperature is gradually decreased as the thickness increase, while there is a fluctuation in the late. As the plate thickness increases, in mm, the bending angle of the plate gradually decreases, and gradually increases in 8mm14mm, and then decreases in the late. Under the given heating conditions, thin plate and the mm thick plate have the best result of deformation. The stress in heat area reaches to the yield stress of Q345, and promotes plastic deformation due to the role of heating temperature gradient and gravity. When the plate has cooled, the residual stress is mainly concentrated at the bottom of the coil.

Abstract: Laser shot peen-forming of sheet metal(or LasershotSM Peening) is a new plastic forming technique for metallic materials, which uses high-power pulsed laser replacing the tiny balls to peen the surface of sheet metal. When the pressure of shock waves induced by laser impresses an inhomogeneous residual stresses distribution in a given depth on the surface of sheet, it responds to the stress by elongating at the peened surface and effectively bending the sheet. In order to investigate the mechanism of laser shot peen-forming, the narrow strip peen-forming experimental of aluminum alloy 6061-T6 was carried out by using a pulsed Nd:glass laser with 0.5Hz repetition-rate. Here, under some given laser energy, laser pulse width, laser beam diameter and pulse repetition frequency and so on, the influence of shot strip interval and shot times on surface residual stresses and the deformation of the sheet is analyzed. The results show that the bending forming of the sheet metal can be found, and the peened surface of sheet metal becomes convex. That the bending increases with shot strip interval increase is not obvious, but it increases with the shot times increase in a proper range of shot times. Besides, because laser shot peen-forming generates compressive residual stresses on the surface, it offers many desirable characteristics in shaped metals and is a valuable technique for producing components for a range of industries.

Abstract: Laser peen forming of sheet metal is a new plastic forming technique based on laser shock waves, which derives from the combination of laser shock processing and conventional shot peening technique, it uses high-power pulsed laser replacing the tiny balls to peen the surface of sheet metal, when the laser induced peak pressure of shock waves exceeds the dynamic yield strength of the materials, the sheet metal yields, resulting in an inhomogeneous residual stresses distribution in depth. The sheet metal responds to this residual stress by elongating at the peened surface and effectively bending the overall shape. On the basis of analyzing the mechanism of laser peen forming, the line-track-peening experiments of 45 steel sheets with 2 mm thickness were carried out; a curved sheet metal with deep layer of residual compressive stress was obtained. The preliminary experiment result shows that laser peen forming can offer desirable characteristics in shaped metals and is a valuable technique for producing components for a range of industries.