Papers by Keyword: Laser Bending

Abstract: The new method of laser prestressed bending of Titanium alloy sheet is put forward in this paper. Titanium alloy sheet is produced pre-deformation by a clamp, the laser beam with some certain intensity scans its surface along the given path, and it is formed due to the thermal effect of the laser to reduce the yield strength of the scanning area and enhance its plastic deformation ability. A feasibility experiment for Ti-6Al-4V sheet is done and the bending effect is remarkable. Laser prestressed bending mechanism is described and the main influence factors are analyzed.

Abstract: The worldwide production of more than half of the material to be processed into sheet metal. Therefore, improving the corresponding forming technology and manufacturing level is a subject of universal significance ^[1,. Sheet metal bending is the technology method that is using high energy laser beam scanning form when the surface of the sheet metal thermal stress caused by non-uniform temperature field to implement plastic forming. Compared with the conventional molding method, the technology neednt die and external force, it is large production flexibility, low cost, and high precision molding^[3,4]. As a new plastic molding method, a laser bending technology has been widespread concern of many scholars at home and abroad^[5]. In this paper that using ABAQUS for ST14 were simulated scanning laser bending. In the simulation, the simulation using shell elements to reduce the amount of computation and shorten the calculation time,finnally use the shell elements replace the solid elements simulations to provide evidence

Abstract: A method is presented based on geometric-curvature characteristics in which a scanning path planning for laser bending of a straight tube into a curve tube in a two- and three-dimensional space. In a two-dimensional (plane) bending, the steel tube is divided into several segments according to the extreme point and inflection point of the desired shape of the tube, taking the extreme point as the initial place of the path planning, using different scanning space for every segment in order to identify the scanning paths. For a tube bending in a three-dimensional space, a projection decomposition method is used, where the three-dimensional is decomposed into two two-dimensions, and respective scanning path planning and process parameters are thus acquired. By combining the data in the two-dimensional planes, the three-dimensional scanning path plan was obtained. Finally, an experimental verification is carried out to bend straight tubes into a two-dimensional sinusoidal and a three-dimensional helical coil-shaped tube. The results show that the proposed method of scanning path planning is effective and feasible.

Abstract: Laser bending process of tubes is a new flexible forming process without rigid tools and external forces. The tube is formed by internal thermal stress induced by laser irradiation. The process simulation of laser bending of tubes is realized numerically. When the other parameters remain invariable, the laser bending angle augments with the increase of the laser power. The laser bending angle decreases with the increase of the scanning velocity. Meanwhile, the bending angle varies with the diameter of the laser spot. The angle begins to decrease when the laser spot diameter get to an optimum value. The bending angle enlarges if the scanning wrap angle augments. The bending angle is largest when the scanning wrap angle is 180°. When the scanning wrap angle is over 180°, the bending angle decreases with the increase of the scanning wrap angle. The relationship between the number of scans and the bending angle is about in direct ratio. The bending angle induced by the first irradiated time is the largest.

Abstract: Laser bending process of sheet metals is a highly flexible forming technique. Simulate model of laser bending process was established by dimension analysis, and the control model of laser bending was achieved with the regression of swatch datum. It was shown that dimension analysis was an effective method in simulating the complex laser bending process, and the control model, which came from non-dimension group datum, was a high-accuracy model in predictive analysis of bending angle.

Abstract: Metal forming by a laser source is an efficient and economical method for forming sheet metal into straight bend and doubly curved shape. It can be most useful in the automation of sheet metal forming. This paper presents an FEM model for three dimensional thermo-mechanical simulation of the laser forming. The aim of this simulation and experimental study is to identify the response related to deformation and characterize the effects of process parameters such as laser power, beam diameter, scans velocity and pulse duration, in terms of bending angle for a square sheet part. Extensive experimentation, including a design of experiments, is performed to address the above-mentioned aims. From these experiments it has been determined that laser forming using Nd:YAG laser is a flexible manufacturing process for steel sheet bending.

Abstract: Stainless steel sheet metals were laser bent by means of a high power diode laser at different values of power and scan velocity. The laser power ranged from 100 to 300 W (with an increment of 50 W); two scan speeds were used, 4 and 8 mm/s, and the number of passes was 2, 4 or 6. In the experimentation, the values of bending angle, microstructure and residual stresses of the laser bended sheet metals were analyzed with regard to the input variables. In particular, residual stresses were evaluated by means of X-ray analysis in terms of first and second order stress. Measurements were performed on the convex surface of the sample in the laser beam action zone. The bending process was numerically simulated by means of a thermo-mechanical finite element model, implemented to predict the sheet metal bending angle as a function of the laser power and scan velocity. The residual stress distribution was extracted from the numerical simulations and its agreement with the experimental observations was discussed. As a general conclusion, the effect of multiple scans is hardly simulated by thermo-mechanical models which do not take into account the material annealing during forming.

Abstract: Bending of metal plates with high-energy laser beams presents a flexible materials forming technique where bending results from the establishment of a steep temperature gradient through the material thickness. This inevitably leads to non-uniform thermal expansion/contraction and subsequently residual stresses. Non destructive residual strain mapping with neutron diffraction through the 8mm thickness of a series WA 300 grade structural steel plate samples, focused on the region straddling the centerline of the heating bead location, shows the presence of large residual stress fields. Directly below the laser track the longitudinal strains are tensile and dominant, normal strains compressive and transverse strains slightly tensile. The magnitudes of the strains decrease outside the width of the laser beam footprint. The first laser pass induces throughthickness strains close to yield, whereafter their magnitudes decrease with increased number of laser beam passes. A comprehensive mapping of the longitudinal stresses as function of the number of laser passes is given.