METHOD OF OPERATION FOR ROLLING ROUND SECTIONS HAVING PREDETERMINED PRECISE FINISHED DIMENSIONS AND GROUP OF ROLLING STANDS FOR CARRYING OUT THE METHOD

MODE DE FONCTIONNEMENT D'UN LAMINOIR POUR LA PRODUCTION DE RONDS AYANT DES DIMENSIONS PRECISES DE FINITION ET ENSEMBLE DE CAGES PERMETTANT D'UTILISER CE MODE DE FONCTIONNEMENT

English Abstract

ABSTRACT OF THE DISCLOSURE
A method of operation for rolling round sections having
predetermined precise finished dimensions in a group of
adjustable rolling stands arranged following a wire rolling train
and including two-high horizontal, vertical and horizontal
rolling stands which are arranged closely one behind the other.
In the first two rolling stands, a pass reduction of between 14%
and 28% is carried out and the rolling speed is adjusted in such
a way that only a low tension occurs, and in the last rolling
stand, the pass reduction is 1% to 5% and the force of the drive
of this rolling stand is limit-adjusted in such a way that the
cross section of the rolled material is not reduced between the
last rolling stand and the preceding rolling stand. The group of
rolling stands for carrying out the method includes a first motor
for jointly driving the first and second rolling stands and a
motor with adjustable current limitation for driving the third
rolling stand.
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Claims

We Claim:
1. A method of operation for rolling round sections having
predetermined precise finished dimensions in a group of rolling
stands arranged following a rolling train and including a first
adjustable two-high horizontal rolling stand, a second adjustable
two-high vertical rolling stand and a last adjustable two-high
horizontal rolling stand, the method comprising carrying out a
pass reduction of between 14% and 28% within the first and second
rolling stands and adjusting a rolling speed of the first and
second rolling stands such that only a small tension occurs in
the rolled section, adjusting a pass reduction of 1% of 5% in the
last rolling stand and controlling a driving force of the last
rolling stand such that a cross sectional size of the rolled
section is not reduced between the last rolling stand and a
rolling stand preceding the last rolling stand.
2. A group of rolling stands for rolling round sections
having predetermined precise finished dimensions, the group
comprising at least a first adjustable two-high horizontal
rolling stand, a second adjustable two-high vertical rolling
stand and a third adjustable two-high horizontal rolling stand,
wherein the first and second rolling stands have a pass reduction
of between 14% to 28% and the third rolling stand has a pass

reduction of 1% to 5%, further comprising a motor for jointly
driving the first rolling stand and the second rolling stand, and
a motor with adjustable current limitation for driving the third
rolling stand.
3. The group of rolling stands according to claim 2,
wherein the rolling stands have a spring characteristic of about
0.001mm/kN.
4. The group of rolling stands according to claim 2,
wherein the rolling stands have rolls which are cantilever-
mounted.
5. The group of rolling stands according to claim 4,
wherein the rolls of the rolling stands are roll disks, and
wherein each roll disk has a diameter of between 130 and 300mm.
6. The group of rolling stands according to claim 2,
wherein the rolling stands are spaced apart from each other by a
distance of about 600 to 750mm.
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7. The group of rolling stands according to claim 2,
further comprising loopers arranged in front of and following the
group of rolling stands.
8. The group of rolling stands according to claim 2,
wherein each rolling stand has a pair of rolls, the rolls having
grooves forming passes, each groove having a bottom portion, a
contour of the bottom portion having an approximately
elliptically oval shape, the groove further having a straight
portion adjacent the bottom portion and extending to an edge of
the groove, and wherein oppositely located straight portions of
the pair of rolls include an acute angle with each other.
12

Description

2 ~
BACRGRO D OF T~E INVENTION
1. ~ield of the Iuvention
The present invention relates to a method of operation for
rolling round sections having predetermined precise finished
dimensions in a group of adjustable rolling stands arranged
following a wire rolling train and including two-high horizontal,
vertical and horizontal rolling stands which are arranged closely
one behind the other.
2. Descriptio~ of the Related Art
Numerous proposals concerning methods of operation of the
above-described type and groups of rolling stands for carrying ;.:
out such methods of operation are known in the art. For example,
Brauer "Weiterentwicklungen der Dreiwalzen-Umformblocke", .
[Further Developments of Three-High Shaping Blocks] Stahl und
Eisen 112/192, No. 7 discloses the arrangement of three-high - .- .
rolling stands in blocks of three stands. The use of two-high
rolling stands with two-sided support of the rolls, also in ;~ :
blocks of three stands, is described in the brochure Morgan :~
:.:
Construction Co. ""TEKISUN BAR SIZING MILL TECHNOLOGY".
The two known methods of operation mentioned above have in
common that they operate with relatively low total pass ~ .
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reductions, i.e, at most approximately 14~, and, as a result,
with a limited capacity, and that the groups of rolling stands
used in the metXods are of relatively complicated construction, -
particularly the roll supports and the roll drives in the blocks
of three-roll stands and the stands themselves in all groups of ~ :~
rolling stands, because of the necessary extremely high stand ~:
stiffnesses with spring characteristics of O.004 mm/kN and less ~. ~
and the required high adjustment accuracy. ~ :
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S~MMARY 0~ T~E INVENTION
Therefore, it is the object of the present invention to
provide a method of operation and a group of rolling stands of
the above-described type which overcomes the disadvantages of the ;-
prior art arrangements described above.
In accordance with the present invention, in the first two
rolling stands, a significantly greater pass reduction of between
14% and 28% is adjusted and the rolling speed is adjusted in such
a way that only a low tension occurs, and in the last rolling -
stand, the pass reduction is adjusted to 1% to 5% and the force
of the drive of this rolling stand is limit-adjusted in such a '-
way that the cross section of the rolled material is not reduced
between the last rolling stand and the preceding rolling stand.
It has been found that the method according to the present
invention makes it possible to roll good round sections whose ;~
finished dimensions are of comparably good accuracy. ; , ;
The group of rolling stands for carrying out the above-
described method of operation may include, in accordance with the
present invention, a first motor for jointly driving the first
and second rolling stands and a motor with adjustable current -
limitation for driving the third r~lling stand.
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In accordance with another feature of the present invention,
the value of the stand springiness of the rolling stands of the
group can be limited to about 0.001 mm/kN. The rolls may be -~
cantilevered, i.e. mounted with one-sided support, and the
rolling stands may be spaced apart from each other by
approximately 600 to 750mm. The rolls may be constructed as roll ~-
disks having a diameter of 130 to 300mm. Conventional loopers
may be arranged in front of and behind the rolling stand group.
The loopers ensure a transition from the preceding and the ;~
subsequent units of the rolling train which does not influence
the dimensions of the rolled material itself and the manner of
operation of the group of rolling stands.
In accordance with another advantageous feature, in the
passes of the first and second rolling stand of the group of
rolling stands, the contours of the bottom portions of the
grooves forming the passes are approximately oval and adjacent
the bottom portion and extending toward the outer edges of the
groove, the contour is a straight line and the straight contours
of opposing rolls in each stand include an acute angle with each
other.

~ ~ a
The various features of novelty which characterize the
invention are pointed out with particularity in the claims
annexed to and rorming a part of the disclosure. For a better
understanding of the invention, its operating advantages,
specific objects attained by its use, reference should be had to
the drawing and descriptive matter in which there are illustrated .. `. .
and described preferred embodiments of the invention.
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BRIEF DESCRIPTION OF T~E DRAWING
In the drawing~
Fig. 1 is a schematic top view of a rolling stand
arrangement according to the present invention; `~
Fig. 2 is a diagram illustrating the relationship between -~
drive motor current and rolling speed; and
Figs. 3, 4 and 5 are schematic illustrations of the passes
of the rolling stands.
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DESCRIPTION OF T$E PREFERRED EMBODIMENTS
As illustrated in Fig. 1 of the drawing, rolling stands 1 --
and 3 are horizontal stands with cantilever-mounted roll disks 4 ~ ~ -
and 5 and the rolling stand 2 arranged between stands 1 and 3 is
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a vertical stand 2. The roll disks 6 of the vertical stand 2 are
also cantilever-mounted, not shown. As is apparent from the
drawing, all stands 1, 2 and 3 are arranged closely one behind
the other. The stands 1 and 2 are jointly driven by a motor 8
through a gear unit 7 and the stand 3 is driven separately by a ;~
motor 9.
The diagram of Fig. 2 illustrates the pattern of the current `
limitation I~ in dependence on the rolling speed, wherein the
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rolling work WA and the mechanical frictions MR are taken into `~
consideration. In order to avoid an influence on the cross ~ ;
section of the rolled material, the power excess required for ~ -
operating the rolling stand is always to be dimensioned smaller
than the tensile strength of the rolled material.
Figs. 3, 4 and 5 show the contours of the passes of stands
1, 2 and 3, respectively. In the bottom portions B of the
grooves forming the passes of stands 1 and 2, the contours are
elliptically oval and the adjacent portions R extending toward
the two edges K of the grooves are straight and the straight
portions of opposing rolls include an acute angle with each
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other, wherein the angle of the straight portion in stand 1 is
30 to 60 relative to the vertical and the angle of the straight
portion of the pass in stand 2 is 30 to 60 relative to the
horizontal. The finishing pass of stand 3 is a round pass.
The invention is not limited by the embodiments described
above which are presented as examples only but can be modified in
various ways within the scope of protection defined by the
appended patent claims.
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