DE102008031569A1 - Mandrel for rolling of hollow ingot, has mandrel bar with thorn arranged at axial end of mandrel bar, where thorn is arranged in relocated manner relative to mandrel bar in more radial direction - Google Patents

Abstract

The mandrel has a mandrel bar (2) with a thorn (4) arranged at the axial end of the mandrel bar. The thorn is arranged in a relocated manner relative to the mandrel bar in more radial direction. The mandrel bar extends in radial or parallel direction.

Description

The The invention relates to a piercer for rolling one on the piercer received hollow block, wherein the piercer a mandrel with a Having arranged at the axial end of the mandrel bar mandrel.

When Raw material for the production of seamless tubes is mostly rolled Round steel, mainly as round casting up to 200 mm diameter, in lengths up to 5 meters in a rotary hearth furnace to a rolling temperature of approx. Brought 1,280 ° C. becomes. After a desiccation of the water, the punching of the Solid block on a piercing mill to a thin-walled hollow block. As a piercing mill This is usually a cross rolling mill used, wherein the hollow tube block rolled in a nip is achieved by a number of rollers, preferably three rollers, the outer circumference roll the tube hollow block, and a mandrel-shaped inner tool, the coaxial is arranged to the tube-hollow block is formed. Here are the Rolling around to achieve a sufficient flow rate an angle between 10 ° and 12 ° to the Walzgutachse inclined.

Of the Hollow block manufactured in the piercing mill is then heated in the same heat Continuous rolling mill (continuous tube rolling) over also a piercer rolled out to a doll. This is an elongation up to a fourfold Stretching reached, d. H. it comes to a cross-section decrease until to 75%. The continuous rolling mill is also called MPM (Multistand Plug Mill) designated.

The Kontiwalzwerk consists mostly of seven to nine in close succession lying rolling stands. The individual rolling stands are each rotated against each other, for example, each 90 °. The Roller peripheral speeds are matched according to the cross-sectional decreases so that there are no significant differences between scaffolds. or compression forces the rolling stock act.

In front the beginning of the rolling process in the continuous rolling mill, the piercer is in pushed or threaded the hollow block. After reaching a certain Position will then hollow block including piercing pin in the Kontiwalzwerk thrusted. The rolling stock is captured by the rolls and smaller by the one from frame to frame rolled rolling caliber rolled on the piercer. It takes the piercer as a result of the increasing rolling stock speed also an ever-increasing Speed on.

is the for the continuous rolling mill achieves the required degree of deformation for the billet, the Luppenspitze in a continuous rolling mill downstream of the continuous rolling mill one. In this, the removal of the piercer takes place on the extent finished doll. By an oval calibration of the mostly used Duo rolls can play a game between the piercer and the rolling stock achieved in the last round caliber evenly around the Scope is distributed, so that the piercer can be solved easily can. Then the retreat takes place of the piercer to the starting position, an ejection of the piercer as well as the insertion of a new piercer. Before a piercer again he must be used chilled be, so that a perforated circle is required. Usually are about eight to ten piercers of the same dimensions in circulation.

One both during skew rolling for punching blocks to hollow blocks as well as when rolling the hollow block to a billet in a multi-stand Konti mills known problem is that the mandrel due to the partial considerable forces Undergoes deformations. Thus, the mandrel moves on the axial End of the mandrel eccentric to the longitudinal axis of the piercer. In the consequence it comes to wall thickness nonuniformity of the hollow block and the doll over their scope. The same problem arises when using Punching mandrels (rolling rods) with insufficient straightness or rigidity.

Of the Invention is therefore based on the object, a piercer of the initially so that it becomes possible, even with certain Deformations of the mandrel a more even wall thickness of the produced Hollow block or to be produced doll.

These Task is inventively characterized solved, that the mandrel displaceable relative to the mandrel in the radial direction is arranged. It is thus the emergence of wall thickness deviations due to radial forces, emanating from the piercer, avoided or at least reduced.

The Mandrel can be a in the radial direction or parallel for this purpose and about have the axial end of the mandrel rod protruding guide portion, in a corresponding, in the radial direction or parallel thereto extending recess engages in the mandrel.

alternative may be provided accordingly that the mandrel bar a has in the radial direction or parallel thereto extending recess, into the one over the axial end of the mandrel protruding out corresponding, in radial direction or parallel thereto extending guide section intervenes.

Further can also two pairs of guide sections and recesses axially adjacent, the two Pairs relative to each other by 90 ° the longitudinal axis the piercer are arranged twisted. This will make it possible that the Mandrel relative to the mandrel in all radial directions movable is.

Between the guide section and the recess may be formed a linear guide. Also between the axial end portion of the guide portion and the ground the recess may be a linear guide be educated. The surface of the guide section and the recess can be provided with a sliding bearing material. In the area of linear guides a lubricant may be arranged. This is it for example, a grease.

According to one Continuing education are in the piercer coolant provided with which it is cooled can. The coolants can Include line elements with which a cooling medium in a through a predetermined axial extent expands inner bore in the punch can be directed.

to Achieving a long life can be provided that the outer surface of the Mandrel and / or mandrel with a layer of wear-resistant Material, in particular of ceramic material, is provided.

Finally, can the mandrel bar over their axial course have a slightly conical shape, which the Deduction of the mandrel from the finished billet in the hollow block favors.

By the measures according to the invention can made a hollow block or a billet with a uniform wall thickness become. At unchanged behind axially fixed mandrel, the mandrel (the mandrel tip) with radial play of a few millimeters arranged. It is so no fixed connection, such as a screw, between Mandrel and thorn in front.

By the proposed embodiment will transmit radially acting personnel avoided or at least reduced by the mandrel on the mandrel.

The Invention is preferred when punching in a cross rolling mill used in the production of a seamless pipe.

In the drawing are embodiments of Invention shown. Show it:

1 schematically the side view of a piercing pin for the production of a billet from a hollow block;

2 an enlarged view of the right part of the piercer after 1 according to a first embodiment of the invention; and

3 in the illustration according to 2 an alternative embodiment of the invention.

In 1 a piercer is to be seen, which is a along a longitudinal axis L erstrechende mandrel 2 has, at its axial end 3 a thorn 4 is arranged. The piercer 1 is used in the manner mentioned above, preferably in a cross rolling mill from a hollow block in a conventional manner to roll a tube blank.

The area where the thorn 4 at the mandrel bar 2 is arranged in is 2 in a first embodiment of the invention. The mandrel 2 has at its axial end portion extending over the entire diameter of the mandrel guide portion 5 on. This extends in the radial direction R. The mandrel 4 has a recess 6 that is considered to be over the entire diameter of the spine 4 trained groove is executed and also extends in the radial direction R. Thus, the forms in the recess 6 used guide section 5 a linear guide 7 that allows the spike 4 relative to the mandrel 2 in the radial direction R is movable. For eccentric tumbling movements of the mandrel 4 facing end of the mandrel 2 allows the linear guide 7 by a movement between mandrel 4 and mandrel 2 in the radial direction that the mandrel 4 retains its position and is driven centrally in the hollow block to be rolled, so that the billet has a uniform wall thickness distribution.

The linear guide 7 can also through the frontal surfaces of the mandrel 2 and the thorn 4 be formed. As in 2 can be seen, lies the axial end region 8th of the guide section 5 the reason 9 the recess 6 across from; Together, these two surfaces form a linear guide 10 ,

As the alternative embodiment according to 3 shows, the guide section 5 ' also in the thorn 4 be arranged; in this case then has the mandrel 2 in its axial end portion of the recess 6 ' to the linear guide 7 to build.

As in 3 is further indicated by dashed lines, in addition to the linear guide 7 a further linear guide can be provided, which is analogous to the linear guide 7 is constructed. However, that is these arranged rotated by 90 ° about the longitudinal axis L. Here is a guide section 5 '' in a corresponding recess 6 '' one. The two pairs of leadership sections 5 ' respectively. 5 '' as well as the recesses 6 ' respectively. 6 '' allow a relative displacement of the mandrel 4 to the mandrel 2 in all radial directions.

The mandrel 2 and the thorn 4 are provided in the region of the forming zones under the rolls of the rolling stands with a wear-resistant material, such as ceramic inserts.

The mandrel 2 can perform a small oscillating movement during the rolling process to avoid partial overheating in the working zone.

In all solutions can be provided that the piercer 1 a continuous cooling during the rolling process in the continuous rolling mill is subjected.

A further development sees a conically shaped mandrel 2 before, what the peeling or rolling off the billet from the mandrel 2 facilitated following the Kontiwalzen.

1

piercer

2

mandrel

3

axial The End

4

mandrel

5

guide section

5 '

guide section

5 ''

guide section

6

recess

6 '

recess

6 ''

recess

7

linear guide

8th

axial End portion of the guide section

9

reason the recess

10

linear guide

R

radial direction

L

longitudinal axis

Claims (12)

Piercer ( 1 ) for rolling one on the piercer ( 1 ) received hollow block, wherein the piercer ( 1 ) a mandrel ( 2 ) with one at the axial end ( 3 ) of the mandrel ( 2 ) arranged thorn ( 4 ), characterized in that the mandrel ( 4 ) relative to the mandrel ( 2 ) is arranged displaceably in the radial direction (R). Mandrel according to claim 1, characterized in that the mandrel bar ( 2 ) at least one extending in the radial direction (R) or parallel thereto and over the axial end of the mandrel bar ( 2 ) protruding guide section ( 5 ), which in at least one corresponding, in the radial direction (R) or parallel thereto extending recess ( 6 ) in the thorn ( 4 ) intervenes. Mandrel according to claim 1, characterized in that the mandrel bar ( 2 ) at least one in the radial direction (R) or parallel thereto extending recess ( 6 ' ) into which at least one over the axial end of the mandrel ( 4 ) protruding, in the radial direction (R) or parallel thereto extending guide portion ( 5 ' ) intervenes. Mandrel according to claim 2 or 3, characterized in that two pairs ( 5 ' . 6 '; 5 '' . 6 '' ) Guide sections ( 5 ' . 5 '' ) and recesses ( 6 ' . 6 '' ) are arranged axially adjacent, wherein the two pairs ( 5 ' . 6 '; 5 '' . 6 '' ) relative to each other by 90 ° about the longitudinal axis (L) of the piercer ( 1 ) are arranged twisted. Mandrel according to one of claims 2 to 4, characterized in that between the guide section ( 5 . 5 ' . 5 '' ) and the recess ( 6 . 6 ' . 6 '' ) a linear guide ( 7 ) is trained. Mandrel according to one of claims 2 to 5, characterized in that between the axial end portion ( 8th ) of the guide section ( 5 . 5 ' . 5 '' ) and the reason ( 9 ) of the recess ( 6 . 6 ' . 6 '' ) a linear guide ( 10 ) is trained. Mandrel according to claim 5 or 6, characterized in that the surface of the guide portion ( 5 . 5 ' . 5 '' ) and the recess ( 6 . 6 ' . 6 '' ) are provided with a sliding bearing material. Mandrel according to one of claims 5 to 7, characterized in that in the region of the linear guide ( 7 . 10 ) A lubricant can be supplied. Mandrel according to one of claims 1 to 8, characterized through a supply of a coolant. Mandrel according to claim 9, characterized in that over a predetermined axial extent expands inner bore in the piercer ( 1 ) is provided as a coolant supply line. Mandrel according to one of claims 1 to 10, characterized in that the outer surface of the mandrel bar ( 2 ) and / or the spine ( 4 ) is provided with a layer of wear-resistant material, in particular of ceramic material. Mandrel according to one of claims 1 to 11, characterized in that the mandrel bar ( 2 ) has a slightly conical shape over its axial course.