To determine the maximum bulge height at bursting pressure, researchers pressurized two tubes of each design until they burst. Two criteria were used to evaluate the engineered tubes: maximum bulge height at bursting pressure and wall thickness uniformity. Figure 4 shows the schematic drawing of this tube design concept. The region of maximum wall thinning after deformation was reinforced with more material in the longitudinal direction. The concept E tube was prepared by following the wall-thinning distribution pattern of the deformed tube shown in Figure 1. 4Of these five (designated A through E), the two that were determined by FEA to have the most potential were concept D, which has a linear wall thickness increase, and concept E, which has a stepped wall thickness increase (see Figure 3). This helps to produce a hydroformed part that has more uniform wall thickness it also reduces the overall weight of the part.įigure 4 Engineered tube concept E has several gradual changes in wall thickness.įive conceptual designs were proposed. In other words, in the tubular preform, the location of the largest deformation is made thicker. Engineered tubes can be designed based on the deformation profile of the expansion during hydroforming. manufactures engineered aluminum tubes using a proprietary technique. 3Įngineered aluminum tubes commonly are used for manufacturing structural frames for bicycles. Tubes that have varying thickness circumferentially and an asymmetrical cross section also are called engineered tubes. Tubes with varying wall thickness along the length are known as butted or engineered tubes (see Figure 2). What Is An Engineered Tube?įigure 3 Engineered tube concept D has specific steps where the tube wall changes from constant thickness to increasing thickness. Two engineered tubes-those that appeared to provide the most uniform wall thickness in bulging-were selected and tested experimentally. Five engineered tube designs were analyzed by finite element analysis (FEA). This hydroforming study, which evaluated the formability limits of tapered tubes as compared to tubes of uniform wall thickness, includes both a description of the methodology used to evaluate various engineered tube designs and a comparison of simulation versus experimental results. Figure 1(left) shows the deformation stages in the hydraulic bulge test, and the right side of Figure 1 shows that maximum thinning occurs at the center of the bulge. The tube is formed freely at the midsection (middle of the bulge). 2In this test, the tube is sealed at both ends and pressurized until it bursts. The hydraulic bulge test was used to investigate the wall thinning that occurs during hydroforming. The material is 6061 T4 aluminum OD = 64.135 mm, length = 230 mm, t o= 2.30 mm.įigure 2 A simple engineered tube has gradual changes in wall thickness. (Right) Measuring the tube's wall thickness along its length after bulging shows that the wall thinned from 2.30 mm to less than 1.85 mm at the bulge center. The most dramatic thinning is at the bulge center. 1įigure 1 (Left) An FEA model at intermediate stages of forming simulation of a uniform-thickness tube shows that the wall remains thick at the tube end but thins in the bulge area. Research conducted at the Engineering Research Center for Net Shape Manufacturing (ERC/NSM) examines the use of extruded aluminum tubes that vary in thickness both circumferentially and axially for these purposes. In such cases, other efforts are made to reduce wall thinning to produce a hydroformed component with nearly uniform wall thickness along its length. Often axial feeding is used to reduce wall thinning, but this is not always possible. Since the volume of tube material (the product of its cross section multiplied by its length) remains constant, the tube wall thins to accommodate the expansion. In tube hydroforming processes, tube is expanded by a high-pressure medium (usually water) until it fills a die cavity.
0 Comments
Leave a Reply. |