Importance

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Abstract

A method and a device for the draw expansion of metal tubes of oval cross-section uses expansion elements drawn unidirectionally through metal tubes by means of draw elements. The expansion elements are fastened to the draw elements by suspension devices which have a hammer-like contour. The draw elements are preferably made of a rod-shaped material. An apparatus of the invention is an apparatus for mechanically expanding metallic tubes, in particular tubes in heat exchangers. Each individual tube to be expanded is held in at least one holding device and passed through by a drawing mandrel with an expanding element. To prevent jamming of the expanding element in one of the holding devices, the holding devices are provided with lateral guides which are resiliently compliant outward in the radial direction. When the expanding element passes through the metallic tube, the tube is expanded in the radial direction. The forces occurring thereby in the axial direction are absorbed by the holding device, since the tube is seated on a stop in the holding device.

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First Claim