Investigation on the influence of mandrel on the forming quality of thin-walled tube during free bending process

Recently, miniaturization and weight reduction have become important issues in various industries such as automobile and aerospace. To achieve weight reduction, it is effective to reduce the material thickness. Generally, a secondary forming process such as bending is performed on the tube, and it is applied as a structural member for various products and a member for transmitting electromagnetic waves and fluids. If the wall thickness of this tube can be thinned and the bending technology can be established, it will contribute to further weight reduction. Therefore, in this study, we fabricated an aluminum alloy rectangular tube with a height H0 = 20 mm, width W0 = 10 mm, wall thickness t0 = 0.5 mm (H0/t0 = 40) and investigated the deformation properties in the rotary draw bending. As a result, the deformation in the height direction of the tube was suppressed applying the laminated mandrel. In contrast, it was found that the pear-shaped deformation peculiar to the ultra-thin wall tube occurs. In addition, axial tension and lateral constraint were applied. Furthermore, the widthwise clearance of the mandrel was adjusted to be bumpy. As a result, the pear-shaped deformation was suppressed, and a more accurate cross-section was obtained.

Deformation Property and Suppression of Ultra-Thin-Walled Rectangular Tube in Rotary Draw Bending

Introduction of a new method for bending of AISI 304L stainless steel micro-tubes with micro-wire mandrel

Size effect mechanism of cross-section deformation and section hollow coefficient-bending degree of the thin-walled composite bending tube

Pipes are widely applied across many industries such as the automotive, aerospace and air conditioning industries. With the development of industrial technology, various pipe materials and various pipe shapes are produced according to the purpose. Many researchers have been studied pipe bending technology to meet these diverse needs, and among them, the long-type elbow is a typical one that changes the moving direction of fluid or gas among various pipe types. Many researchers work on the pipe segment. In-process push-bending used in pipe bending is a bending process where a cut pipe is inserted into a die. Push-bending is effective for reducing the weight of parts that do not induce material loss, but the process is more complicated than the draw-bending process. In this study, we proposed an analytical model for a push-bending process in which a joint type mandrel was added to a long-type elbow made of C1220 material for weight reduction. The forming analysis is to verify the experiment by comparing the analysis result and the experimental result through the forming analysis software DEFORM to confirm the change of the wrinkle and the thickness of the bent pipe. In addition, we confirmed the wrinkling of the bent pipe and the die non-contact phenomenon depending on the angle and position of the joint mandrel and presented the optimum angle and center of gravity position of the joint mandrel using the experimental design method.

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Guanghui Wang

Papers

Prevention of defects by optimizing mandrel position and shape in rotary draw bending of copper tube with thin wall

Strengthening mechanisms of a heterostructured pure aluminum with extraordinary mechanical properties