Piercing mandrel having an improved service life for producing seamless tubes

Abstract

The invention relates to a piercing mandrel(4)for piercing heated round blooms(3)made of metal,in order to produce seamless tubes (6),the piercing mandrel comprising a piercing mandrel nose(4.2)and a piercing mandrel main body(4.1)that can be connected to a mandrel bar(5).According to the invention, the external diameter of the piercing mandrel nose(4.2)is conically tapered in the longitudinal direction towards the piercing mandrel main body (4.1),in order to increase the service life of the piercing mandrel when cross-roll piercing round blooms made of metal,in particular made of more highly alloyed steel materials that are difficult to form,while taking into consideration a qualitative improvement of the inner surface of the pierced round blooms,and while reducing the cost of tools.

Description

technical field [0001] The invention relates to a punch for producing seamless pipes by punching hot circular metal blocks. The punch includes a punch nose and a punch body attachable to a punch mandrel. Background technique [0002] As is known, seamless pipes are produced as follows: Using axially fixed internal tools, the raw material, the so-called round block, formed in the original cylindrical shape and heated in an annular furnace is processed in a piercing mill to produce a tubular hollow block . Wherein, the internal tool includes a punch and a punch mandrel. [0003] To make seamless hollow block tubes, after gripping the tubular hollow block through the piercing mill, the tubular hollow block is conveyed through the piercing mill in a helical form, whereby the tubular hollow block passes through an axially fixed internal tool and is The tubular hollow block is wall-ironed in a subsequent step of the method to produce a seamless tube. The round block is pushed ...

AI Technical Summary

Problems solved by technology

Disadvantages of this construction include that there is still insufficient cooling of the punch tip itself, and that the oblique position of these coolant outlets on the one hand complicates the production process and on the other hand no longer reliably prevents passage during the punching process. Vent closure due to contact of punch tip with pellet material

Another disadvantage is that the one-piece design of the punch makes it necessary to replace the entire punch if it becomes worn

The disadvantage of this solution is that it does not cool the punch tip and still does not significantly increase the service life in the case of difficult-to-machine materials

[0011] All of the measures already mentioned in this article are not suitable for effectively reducing the thermo-mechanical loads on the punch during cross-rolling, so that, from an economical and qualitative point of view, when they are used for difficult-to-machine materials, Inability to achieve a sufficiently long service life

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