DE433344C - Rolled stock of polygonal shape for pipe rolling - Google Patents

Description

Rolled stock of polygonal shape for pipe rolling. Round metal casts, which are used to manufacture hollow bodies for seamless tubes in cross-rolling mills, require great care in terms of weldability and elongation during manufacture, with the greatest possible exclusion of gas, slag and stone inclusions.

As is known, the production of such blocks has been achieved without problems up to certain diameters. On the other hand, it is known that with a larger block diameter, even if the most advantageous properties of the S. 11. material and the most suitable casting temperature are maintained, phenomena occur on the casts which lead to internal or external defects in the perforated hollow bodies. Therefore, the blocks required for the production of tubes of large dimensions have recently been cast at a lower temperature in order to avoid cracks in the blocks. The cooler casts, however, include gases, slag and stone particles that can rise to the surface when the blocks are cast hotter. These inclusions, together with small internal cracks, sometimes lead to greater damage than the external cracks that occur in the case of hot-cast round blocks when they shrink because the outer shell does not yield. The invention is based on the knowledge that the stated disadvantages can be eliminated by changing the outer shape of the blocks.

It is known that in the manufacture of forgeable metal castings; For heavy forged pieces or the like, the blocks are not round, but polygonal are so that the material in the flats of the body without cracking after the : Can shrink towards the middle and the block remains intact. For the manufacture of hollow bodies In the cross-rolling mill, however, a multi-edged ingot has not yet been able to be used will. No suit cone on the work rolls of a piercing mill either Bauart is able to attack flattened blocks.

According to the invention, the use is made possible in that the Attack end on the roller block is a suitable taper of the roller corresponding rounded shape is granted. The rounding can be turned, forged, pressed or cast directly in the form (mold) or on any other Way to be executed. The tightening cone of the work rolls grips and promotes the round part of the block forward, with the gradually following polygonal part of the block is progressively rounded and punched until it finally has the shape of the Hollow stick receives like a hollow body rolled from a round block.

In the drawing the invention is illustrated, namely show) Fig. I and z two stages of the action of the rollers on the block. Abl). 3 shows a longitudinal section through a mold used for production and a top view on the block cast in it.

In the drawing, A denotes the Valzen. B is the polygonal block with the rounded parts B, at one or both ends, as well as with the edges B- In the manner shown in fig A, the rollers A the round part B1 of the block B; the moment is shown where A, the block already up to the high point A, the work rolls pulled forward and with has led the front end against the rolling mandrel C. Fig. A illustrates a later stage of work; on the block that has advanced between the rollers is at B3 the previously angular part B, already partially rounded and perforated, and the other The movement of the block until it is finished is completely secured.

In the shape illustrated in Fig. 3, the upper part D is round (slightly tapered) for the design of the block ends, the part Dl is polygonal.

The angular shape of the cast blocks with rounded ends ensures the production of flawless casts for pipes with large cross-sections in the between advantageous casting temperature lying within certain limits. This results in longitudinal cracks avoided that the material on the sides of the = block at irdemer - StettF-der-Blocklänge can dwindle towards the middle. Gas bubbles, slag and stone particles can more easily rise to the surface without becoming trapped. Furthermore, this is Throws that sometimes occur in the molds for round blocks, which is often the cause the blocks are prevented from sticking in the molds; there will also be imperfections avoided on and under the upper skin.

The invention extends to the production of rolled stock for pipes all diameters, as far as angular blocks with round ends are possible.

Claims (1)

PATENT CLAIM: Rolled stock of polygonal shape for pipe rolling, characterized in that the polygonal cross-section of the block towards one end towards or towards both ends merges into a round cross-section in such a way that the inclined rolling mill can grasp the ingot.