Limitation of dieless forming technique and application to triple-layered heat exchangers: dieless forming technique for double-layered heat exchangers III

摘要

A uniform moment bending method has been used in manufacturing a heat exchanger for packaged air conditioning units. This is because this method offers flexibility during the manufacturing process in terms of the bending radii and forming angles. It has already been adopted for double-layered heat exchangers, but to cope with the design changes on a number of layers or bending radii, limitations of the processing conditions had to be considered. Both sides of the portion of the workpiece to be bent have to be gripped to proceed with this method. The relationship between the grip length and the bending radius has been estimated through both experiments and calculations. As a result, for example, the minimum length of the gripper to form a 107.8 mm radius is considered to be 125 mm. As for triple-layered workpiece forming, a machine for practical use has been adopted in an actual manufacturing line. This can be accomplished using a four-axis controller as has been used previously for bending a double-layered workpiece. In this case, by controlling only the inner and outer layer positions, the middle layer position will be maintained by both controlled layers, which results in a simultaneous bending without workpiece damage.