| 摘要 |
The present invention relates to a cooled piercing (boring) mandrel intended especially for the manufacture of weldless tubes, having a general ogival shape. This mandrel is characterised in that it comprises a relatively thin outer casing 1 in contact with the material to be formed, intended to provide the viscous flow of this material, an inner body 2 of the same shape as the outer casing 1, fitted tightly and fixed to the inside of this casing 1, in which body are formed conduits 5, 9, 11 for the circulation of a coolant fluid, and a nose 3 fixed at the end of the casing 1 and made of an extra-hard material in order to be able to withstand the forces of the hot mechanical working without deforming. <IMAGE>
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