Note: Descriptions are shown in the official language in which they were submitted.
2~50~
NO-TWIST SLIT-ROLLING APPROACH ("NTA") APPARATUS AND
METHOD FOR MANUFACTURING STEEL REINFORCIN~ ROD
FIE~D OF THE INVENTION
This invention pertains to the field of
manufacturing steel reinforcing bar.
BACXGROUN~ OF THE INVENTION
Various methods of manufacturing steel
reinforcing bar have been well-known in the art for
many years. Reinforcing bar is vital to the
construction of roads, bridges, and the other concrete
structures. In the manufacture of reinforcing rod, hot
steel stock or rod is typically passed between several
pairs of rollers, termed "rolls, n driven in opposite
directions, which is termed "rolling. n Repeated
rolling is necessary to give the finished steel
reinforcing rod sufficient tensile strength and rolling
also aids in descaling, or the removal of surface
imperfections on the steel rod. The pair of rolls are
usually mounted inside a housing on sha~ts, and the
complete unit is commonly known as ~a stand.~ The
steel rod assumes the shape of the roll profile as it
passes through the stand. In the case of round steel
reinforcing bars, the steel rod must be rolled by
alternate stands on opposite sides so that the
resulting product is symmetrical.
In a conventional rolling mill layout, all of
the stands are arranged on the same axis, and the steel
rod are twisted approximately 90~ by either twist guides
; or twist rollers as they enter the next stand. This is
.
203~
termed the ~twist-method.~ Use of this method for
production of steel rod has often been troublesome,
because an incorrect setting of the twist angle, or
wear in the twist rollers can prevent the steel rod
from entering the next stand in a proper alignment, or
at al}. Despite attempts to overcome these problems,
they remain a major source of downtime. Use of the
twist-method to produce steel rod is also problematic
in that there is a greater possibility of surface
defects resulting from contacts of the steel bar with
the twist guides or twist rollers.
The development of the arrangement of stands in
alternate horizontal and vertical axes has eliminated
many of the inherent shortcomings of the twist-method,
especially in the rolling of round products. This
arrangement has been commonly adopted by modern-day
rolling mills, especially in the production of alloy
steel products, where the surface finish of the final
product is very critical. - -
In the production of small diameter round steel
reinforcing bar, because of its small cross section and
hence light mass per length, very high rolling speeds
must be maintained in order to achieve hiqh
productivity. However, with higher rolling speeds, the
problems associated with twisting of the bar betweQn
the stands are amplified. Further problems arise with
the collection of the finished steel reinforcing bars
after the rolling process at such high speeds, and the
collection is usually done by coiling the bars as they
leave the rolling process, and thereafter, the steel
rod must be straightened by a separate process. At
lower speeds, the finished straight rod can be
deposited directly onto cooling beds.
Recently, a new method for producing steel
reinforcing bar has been developed which involves
rolling the steel stock into a profile which is later
slit and is further rolled into the required shape and
203~a~
sizes. This is termed the ~slit-rolling~ method. The
advantage of this system is that the same productivity
can be main~ained at half the rolling speeds and hence
the finished bars can be delivered straight onto
conventional cooling beds. However, the adoption of
the slit-rolling method using either t~e conventional
horizonal stand arrangement or the horizonal and
vertical stand arrangement still has inherent
shortcomings as described below.
Figure 1 illustrates the typical horizontal
stand slit-rollinq mill, without showing rod twisting
guides or twisting rollers, the base, or the turning
means for the rollers. Twisting of the steel rod
remains necessary between all stands including ~etween
the final two stands 17 and 18. The twisting of each
rod emerging from stand 17 is critical because if
problems occur on one of the stands, the production on
the other stand is intexrupted as well, thereby causing
a bottleneck in production.
A typical horizontal and vertical slit-rolling
mill, without showing rod twisting guides or twisting
rolls, or the base, or the turning means for the rolls,
is illustrated in Figure 2. Although the majority of
the twisting is eliminated, twisting of the steel rod
remains necess~ry between stands 14 and 15 and from
stand 15 to 16. Furthermore, the overlapping of the
slitted oval section from stand 17 to 18 involves
bending the steel rod at its longer axis on its cross
section, which results in the full advantage of the
horizontal and vertical arrangement not being realized.
SUMMARY OF THE INv~..lON
The present invention provides an improved
apparatus and method for producinq steel rein~orcing
bar which eliminates the shortcomings found in the
prior art methods of producing steel reinforcing bar,
and the method is called ~the NTA ~ethod,~ (~NTA~
2 ~ 0 ~
stands for no-twist approach). Figures 3 and 4
illustrate two embodiments of the apparatus employing
the NTA method without showing the base, the housings
for the stands or the means to turn the rolls
comprising the stands, which are standard design, and
which are deleted for clarity of presentation.
A first feature of both embodiments of the
apparatus is the arrangement of the sides of the rolls
of stands 13 and 14 at 45~ to a vertical plane through
A-A and at approximately 90~ to each other, resulting in
the steel stock being presented at stand 15 without
twisting being required.
A second feature of the first embodiment of the
apparatus is its arrangement of the sides of the rolls
of stand 17 being vertical and the stand 18 being
horizontal to the vertical plane through A-A and at
approximately 90~ to each other, which accomplishes the
goal of rolling the steel rod without the need for
twisting.
A second feature of the second embodiment of the
- apparatus is its arrangement of the sides of the rolls
of stands 17' and 18' at approximately 45~ in opposite
directions to the vertical plane through A-A and at
approximately 90~ to each other, which accompllshes the
goal of rollinq the steel without the need for
twisting.
BRIEF DESCRIPTION OF THE DRAWINGS
In describing both embodiments of the apparatus,
reference will be made to the accompanying drawings
wherein:
FIG. 1 is a diagram of a conventional slit-
rolling mill incorporating horizontal stands.
FI~. 2 is a diagram of a conventional slit-
rolling mill incorporating vertical and horizontal
stands.
20~ 3
FIGS. 3 and 4 are schematic side views of the
two embodiments of the apparatus without showing the
base, the housing for the stands, or the means to
rotate the roll comprising the stands, with the deleted
components being of standard design. The two
embodiments are similar except for the orientations of
stands 17 and 17' and 18 and 18'.
FIGS. 5-13 illustrate the stand and steel rod at
various stages of rolling common to both embodiments
shown in FIGS. 3 and 4.
FIG. 5 is a cross sectional view of the steel
rod prior to entering stand 13 viewed through plane A-
A.
FIG. 6 is a view of stand 13, viewed through
plane A-A.
FIG. 7 is a cross-sectional view of the steel
rod after rolling by stand 13 and aligned to enter
stand 14, viewed through plane A-A.
FIG. 8 is a perspective drawing of stand 14,
viewed through plane A-A.
FIG. 9 is a cross section of stock after being
rolled by stand 14, viewed through plane A-A~
FIG. 10 is a diagram of stand 15, viewed through
plane A-A.
FIG. 11 is a cross sectional view of the steel
stock after beinq rolled by stand lS and aliqned to
enter stand 16, viewed through A-A.
FIG. 12 is a drawing of stand 16, viewed through
plane A-A.
FIG. 13 is a cross-sectional view of one of the
steel rods after being rolled and slit by stand 16 and
before entering stands 17, viewed through plane A-A.
FIGS. 14-17 illustrate the additional stands and
cross-section of steel rods at various stages of
rolling unique to the first embodiment as shown in FIG.
3.
2~3550~
FIG. 14 is a drawing of stands 17, viewed
through plane A-A.
FIG. 15 is a cross-sectional view of the steel
rods after being rolled by stand 17 and aligned to
enter stand 18, viewed through plane A-A.
FIG. 16 is a drawing of stand 18, viewed through
plane A-A.
FIG. 17 is a cross-sectional view of the
finished steel reinforcing bar, viewed through plane A-
A.
FIGS. 18-21 illustrate the additional stands and
cross-section of steel rods at various stages of
rolling unique to the second embodiment as shown in
FIG. 4.
15FIG. 18 is a drawing of stands 17', viewed
through plane A-A.
FIG. 19 is a cross-sectional view of the steel
rods after being rolled by stand 17' and aligned to
enter stand 18', viewed through plane A-A.
20FIG. 20 is a drawing of stand 18', viewed
through plane A-A.
FIG. 21 is a cross-sectional view of the
finished steel reinforcing bar, viewed through plane
A-A.
DETAIL~D DESCRIPTION
Referring now to the drawings, there are
illustrated in Figs. 3 and 4, perspective schematic
views of the first and second embodiments of the
apparatus embodying the present invention. For the
sake of clarity, the base of the apparatus, the housing
for the stands, and the driving means for turning the
rolls comprising the stands are not shown. The
apparatus allows the steel rod to be rolled and shaped
without requiring the steel rod to be twisted. As can
be seen from Figs. 3 and 4, the stands are arranged
203~
with their sides in various orientations to the
vertical plane through A-A.
The first embodiment of the invention, shown in
Fig. 3, allows steel reinforcing rod to be manufactured
as follows: The starting steel stock, shown in Fig. 5,
is rolled by a first stand 13, with rolling surfaces
231 defining an oval, which is oriented with the sides
233 of the rolls 23 offset approximately 45~ in one
direction from the vertical plane A-A. First stand 13
lo is shown in greater detail by Fig. 6. The resulting
rod, which has an oval shaped cross-section,
illustrated in Fig. 7, is next rolled by a second stand
14, shown in greater detail in Fig. 8, which stand has
rolling surfaces 241 defining a square and which is
oriented with the sides 243 of the rolls 24 offset
approximately 45~ in a second direction from the
vertical plane A-A. The oval shaped steel rod does not
require twisting to enter the second stand 14 as the
longer dimension of its oval cross-section as rolled is
already oriented diagonally with the square rolling
surfaces of the second stand 14.
The resulting steel rod, having a generally
square cross-section, illustrated in Fig. 9, is next
rolled by stand 15, having rolling surfaces 251
defining two s}ightly overlapping circles, which is
oriented with the sides 253 of its rolls 25 offset
approximately 0~ from the vertical plane A-A, as can be
best seen in Fig. 10. The steel rod which emerges from
stand 15 has a cross-section of two slightly
overlapping circles, depicted in Fig. 11. Following
this, the steel rod is rolled by a stand 16 having the
same spatial orientation as the preceding stand, but
with a rolling surface 261 defining two abutting
circles, as is best shown in Fig. 12. The rolling by
stand 16 splits the rod into two generally circular
rods, one of which is shown in Fig. 13.
- ~ ~ ~
~3~0~
The two rods are next presented to be rolled one
each by two separate lines of stands 17-18, with the
first stand 17 in each line of stands being aligned
wit~ the sides 273 of its rolls 27 offset approximately
90~ from the vertical plane A-A, and with rolling
surfaces 271 generally defining a circle, as shown in
Fig. 14. The steel rods resulting from rolling by
stands 17 have a generally circular cross-section,
shown in Fig. 15. Next, the two steel rods are rolled
one each by stands 18 defining a generally circular
rolling surface 281 and aligned with the sides 283 of
their rolls 28 offset approximately 0~ from a vertical
plane, as can be seen in Fig. 16. The offsetting of
the orientations of the two stands allow the steel rods
to be rolled uniformly on all sides without twisting of
the steel rod being required. The final product is two
steel rods with circular cross-sections, one of which
is shown in Fig. 17.
The second embodiment, shown in Fig. 4, is
similar to the first embodiment, except for the
orientation of the stands in the lateral lines of
stands located at the end of the apparatus where the
rolling of the steel rod is finished. The description
of the first stages, recited above with reference to
Figs. 3-13 remains the same.
In the second embodiment, the two rods are
rolled after stand 16 by two separate lines of stands
with the first stand 17' in each line of stands being
aligned with the sides 273' of their rolls 27' offset
approximately 45~ in one direction from the vertical
plane A-A, and with the rolling surfaces 271' defining
an oval, best shown in Fig. 18. The steel rods
resulting from rolling by stands 17' have an oval
cross-section, as shown in Fig. 19. Next, the steel
rods are rolled by stands 18' having a circular cross-
section and aligned with the sides 283' of their rolls
28' of~set approximately 45~ in a second direction,
2~35~
opposite the first direction, from the vertlcal plane
A-A. The offsetting of the two stands by 45~ from the
vertical plane and at 90~ to each other allows the steel
rods to be rolled uniformly on all sides without
twisting being necessary. The final product is two
steel rods with circular cross-sections, one of which
is shown in Fig. 21.
Turning now to the detailed description of the
two embodiments, the stand and rolling product are as
follows:
' ' Figs. 5 through 13 are common to both
embodiments of the apparatus, and are views through
plane A-A, showing the orientation of the stands and
the cross-sections of the steel rod after beinq rolled
by each stand.
Fig. 5 is a cross-sectional diagram of the steel
stock prior to being rolled by stand 13.
Fig. 6 provides a detailed view of stand 13,
without showing its housing, viewed through plane A-
A. Stand 13 comprises two adjacent rolls 23 withconcave semi-oval shaped rolling profile, each roller
turning in opposite directions along their parallel
shafts 232, and with the sides of the rolls 233 offset
approximately 45~ in one direction from the plane
through A-A.
Fig. 7 is a cross-sectional view of the oval
shaped steel rod after rolling in stand 13 with its
longer dimension offset at approximately 45~ from the
plane through A-A.
Fig. 8 illustrates stand 14, without showing its
housing, viewed through plane A-A. Stand 14 comprises
two adjacent rolls 24 with triangular shaped roll
profiles, each roller turning in opposite directions
along their parallel shafts 242 and with the sides of
the rolls 243 offset approximately 45~ in an opposite
direction from the plane through A-A as the rolls in
stand 13. The sides of the roll 23 and 24 comprising
~3~0~
-- 10 --
stands 13 and 14 are thus offset approximately 90~ from
each other.
Fig. 9 is a diagram of the square steel rod
after being rolled by stand 14, viewed through A-A.
Fig. lo is a view of stand 15, without showing
its housing viewed through A-A. Stand 15 comprises two
adjacent rolls ~5 with roll profiles 251 in the shape
of two slightly overlapping semi-circles, each roll
turning in opposite directions along their parallel
shafts 252, with the sides of the roll 253 parallel to
the plane through A-A.
Fig. 11 is a cross-sectional view of the steel
rod as it emerges from stand 15, viewed through plane
A-A.
Fig. 12 is a view of stand 16, without showing
its housing, viewed along plane A-A. Stand 16
comprises two adjacent rolls 26, with roll profiles 261
in the shape of two adjacent semi-circles, each roller
turning in opposite directions along their parallel
shafts, 262, with their sides 263 parallel to the plane
through A-A. Stand 16 slits the entering steel rod
shown in Fig. 11 into two steel rods.
Fig. 13 is a cross-sectional view of the steel
rod as it emerges from stand 16, viewed through plane
A-A.
Figs. 14-17 are unique to the first embodiment.
Fig. 14 is a view of stands 17, without showing
their housing, viewed through plane A-A. Stands 17
comprise two adjacent rolls 27, with roll profiles 271
in the shape of a concave semi-circle, each roll
turning in opposite direction along their parallel
shafts 272, with the sides of the rolls 273 offset
approximately 0~ from the plane through A-A.
Fig. 15 is a cross-sectional view of the steel
rods as they emerge from stands 17.
Fig. 16 is a view of stands 18 without showing
their housings, viewed through plane A-A. Stands 18
'' 2~3~0~
comprise two adjacent rolls 28, containing roll
profiles 281 in the shape of a concave semi-circle,
each roll turning in opposite direction along their
parallel shafts 282, with the sides of the rolls 283
offset approximately 90~ from the plane through A-A as
the rolls in stands 17.
Fig. 17 is a cross-sectional view of finished
reinforcing rod as they emerge from stands 18.
The second embodiment of apparatus is
substantially similar to the first embodiment, except
with respect to the orientation of its stands 17' and
18', and these features are illustrated in Figs. 18-
21.
Fig. 18 is a view of stands 17', without showing
their housing, viewed through plane A-A. Stands 17'
comprise two adjacent rolls 27', with roll profiles
271' in the shape of a concave semi-oval, each roll
turning in opposite direction along their parallel
shafts 272', with the sides of the rolls 273' offset
in one direction by approximately 45~ from the plane
through A-A.
Fig. 19 is a cross-sectional view of the steel
rods as they emerge from stands 17'.
Fig. 20 is a view of stands 18' without showing
their housings, viewed through plane A-A. Stands 18'
comprise two adjacent rolls 28, containing roll
profiles 281 in the shape of a concave semi-oval, each
roll turning in opposite direction along their parallel
shafts 282', with the sides of the rolls 283' offset
approximately 45~ in an opposite direction from the
plane through A-A as the rolls in stands 17'.
Fig. 21 is a cross-sectional view of the
finished reinforcing rod as they emerge from stands
18'.
3SIt should be borne in mind that the drawings are
not rendered in actual scale so that certain features
of the invention can be brought out and depicted.
2~3~5~
- 12 -
The drawings and the foregoing description are
not intended to represent the only form of the
invention in regard to the details of its construction
and manner of operation. In fact, it will be evident
to one skilled in the art that modifications and
variations may be made without departing from the
spirit and scope of the invention. Changes in form and
in the proportion of parts, as well as the substitution
of equivalents, are contemplated as circumstances may
suggest or rendered expedient; and although specific
terms have not been employed they are intended in a
generic and descriptive sense only and not for purposes
of limitation. The scope of the invention being
delineated in the following claims.
