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Патент USA US2405274

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Aug. 6, 1946.
J. D. STlTEs
2,405,Z 74
REINFORCEMENT BAR AND METHOD OF MAKING SAME
. Filed July 24, 1943
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2 Sheets-Sheet 1
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lNEN-TOR
JOSEPH D 57/755
BY
ATT
NEY
I
Patented Aug. 6, 1946
2,405,274 »
UNITED STATES PATIENT oFFIcE
2,405,274
REINFORCEMENT BAR AND METHOD OF
MAKING SAlVIE
Joseph D. Stites, Chicago, 111., assignor to Ameri
can Isteg Steel Corporation, New York, N. Y., a
corporation of New York
Application July 24, 1943, Serial No. 496,024
8 Claims.
(01. 72—111)
l
The invention relates to reinforcement bars v
for concrete structures and the like, and to meth
ods of manufacturing such bars to give them
improved physical properties. It relates in par
ticular, to improvements in the type of twisted
reinforcement bar shown in my prior patents,
No. 2,256,060, and No. 2,324,651, and in the man
ufacture of such improved bars.
It is known that the bond value of reinforce
ment bars for concrete structures can be in
creased by providing them with transverse, diag
onal, or spiral ribs, and many forms of bar hav
2
Another object is to provide a reinforcement
bar which will increase the bending strength
of concrete sections produced therewith to a
greater extent than is possible with high bond
value reinforcement bars of types known here
tofore.
Other objects and advantages will appear as
the description proceeds.
In the drawings, wherein I have illustrated
10 certain preferred embodiments of my invention:
Fig. l is a plan view of a short length of rein
forcement bar as produced by the ?rst step of
ing such ribs have been devised. However, the
my process.
forms of ribbed bar heretofore proposed have been
Fig. 2 is a view of the same bar after twisting
unsuited inherently to twisted bar of the type 15 and stretching.
shown in my prior patent, to which reference
Fig. 3 is a cross-sectional view of the untwisted
has been made above. In those patents, I have
bar, taken as shown at 3——3 in Fig. 1.
disclosed another form of transverse rib which
Figs. 4, 5 and 6 are cross-sectional views of the
is applicable to twisted bar of dumb-bell cross
twisted bar, taken as shown, respectively, at 4-4,
section for preventing rupture during the twist
5—5 and 6-6 in Fig. 2.
ing operation. It has been an object of my pre
Fig. 7 is a view similar to Fig. 3, but illustrat
sent invention to provide an improved form and
ing a modi?ed rib construction.
arrangement of transverse ribs in such twisted
Fig. 8 is a view similar to Fig. 1, showing a
bar which will increase the bond value, and which
further modi?cation.
will eliminate, or greatly reduce, the manufac 25 In accordance with the invention I ?rst pro
turing'problems encountered with spiral ribs and
duce, as by usual rod rolling methods, a ?at bar
other rib forms of the prior art.
of the general form shown in Figs. 1 and v3,
Twisted bars of the type disclosed in my prior
having two parallel rod-like sections 9 joined by
patents, No. 2,256,060 and No. 2,324,651, possess
an integral Web ID. Each rod-like section 9 pref
recognized advantages over other types from the
erably is substantially circular in cross-section,
standpoint of tensile and bending strengths, as
or slightly ovoid as best shown in Fig, 3. ' The web
well as bond value. I have discovered that these
l0 preferably has across-section made up of
advantageous properties can be enhanced still
two opposed arcs which are tangent to the arcs
further by the provision of the novel rib form
of the sections 9.
that I shall now described. I have discovered,
A series of parallel transverse ribs I! extend
also, that the twisting process can be utilized to
across the web Ill and around at least one side
give to the transverse ribs 3, con?guration which
of the section 9, and a second series of such ribs
is peculiarly adapted to increase bond values.
l2 extend across the web and around the other
Concomitantly with this discovery I have found
side of the sections 9. The two series of trans
that parallel transverse ribs which initially are
verse ribs are arranged in staggered relation
spaced in a manner not calculated to have any
ship, as clearly shown in Fig. 1, so that each
important e?ect on the tensile strength of the
rib I I is exactly half way between a pair of adja
bar, can be so deformed during the twisting op
cent ribs lZ. For ease of rolling, the transverse
eration as to enable them to contribute substan
ribs may be rounded, or may have inclined sides,
tially to the tensile strength of the bar, pro
as shown at l3, so that their cross-sectional con
vided their original disposition and spacing bears
?guration approximates a trapezoidal form.
a certain relationship to the pitch of the helix
The flat bar of Fig. 1 is twisted to produce
of the twisted bar. Accordingly, a. further object
the helical structure shown in Fig. 2. In this
of my invention is to provide a method of in
step of the method. the length of the bar prefs
creasing the tensile strength of a twisted rein 50 erably is maintained constant. which means that
forcement bar without increasing the weight of
the length of each rod-like section 9 will be some
the metal in the bar per unit of length.
what increased. The stretching of the bar in
Another object is to provide an improved meth
this manner results in a desirable amount of
od of manufacturing reinforcement bars of the
cold working which improves the physical prop
character described.
55, erties of the bar.
2,405,274
3
An important feature of my invention resides
in spacing the transverse ribs closely together so
that, in the helical structure produced by the
twisting and stretching operation, portions of
ribs on opposite sides of the bar will be brought
into common planes normal to the axis of the
helices, or so that all planes normal to the axis
of the helices will intersect at least a portion of a
4
are arranged in general at an acute angle to the
longitudinal axis of the bar. The ends of the
ribs are reversely curved, as shown at a in Fig. 2,
forming hook-like portions which are particularly
effective in increasing bond between the rein
forcement bar and the concrete of the structure
in which it is used. I have found that concrete
sections reinforced with bars of the form I have
described, have increased bending strength. I at
in Figs. 4, 5 and 6, where the intersections of the 10 tribute this improvement in part to the increased
bending strength of the bar itself, and in part to
respective transverse planes-ei. e. planes normal
‘to the axis of the helices—with the transverse I the increased bond between the bar and the con
crete.
ribs are shown at the portions which have been
The ends of the ribs l I and l2 preferably blend
lined horizontally to represent the color blue.
into the sides of the sections 9, as shown at M in
In other words, I have discovered that it is possi
Fig. 3, where they meet longitudinal ribs l5 ex
ble to so adjust the spacing and disposition of
tending along the edges of the bar. The ribs l5,
the ribs II and I2, formed by‘ the rolling opera
besides increasing the bond value of the twisted
tion, in relation to the pitch of the helices pro
bar, simplify the manufacture of the bar by
duced by the twisting and stretching operation,
reason of the provision for a certain amount of
that all planes normal to the axis of the helices
?ashing between the rolls of the mill used in roll
will intersect at least a portion of a transverse
ing the ?at bar. These ribs, like the transverse
rib. ‘This means that the factor of
transverse rib.
These conditions are illustrated _
ribs H and IE, may be rounded or may have in
longitudinal rib spacing
clined sides as shown so that they have a cross
sectional con?guration which is substantially
trapezoidal in form. The ribs I5 may, if desired,
can be utilized in such a manner as to increase
be omitted.
the tensile strength of the bar. I have found, for
If desired, the transverse ribs may join the lon
example, that when the ribs on each side of the
gitudinal ribs in the manner shown in the modi
bar are spaced apart by a distance equal to ap
embodiment of Fig. '7. Here, the transverse
proximately % of the major diameter, D, of the 30 ?ed
ribs l5, instead of blending into the wire sections
bar,1or less, a twisting to a helical pitch of 12/1
9, come approximately flush with the tops of the
will result in the condition named, wherein all
longitudinal ribs I5. Also the central portion of
planes, normal to the axis of the helices will in
each rib I6 is made a little higher to further
tersect at least a portion of a transverse rib.
strengthen the web M, as shown at H.
' V
, helical pitch
The width and shape of the transverse ribs will
in?uence the spacing/pitch factor, so that in
some cases a spacing larger than 5/8D will result
In Fig. 8, I have shown another modi?cation of
the invention in which the transverse ribs are
given a slight initial pitch in the rolling opera
in the desired condition described. Also, if the
tion. The series of ribs H! are arranged at an
transverse ribs be given a slight initial pitch in
acute angle to the longitudinal axis of the bar.
40
they rolling operation, the spacing can be in.
A second series of ribs 19 at the other side of
creased, as I shall discuss later in describing a
the bar, likewise arranged at an acute angle to
modi?ed form of the invention. In every case
the longitudinal axis, are disposed midway’be
the proper relation of spacing, to pitch can be de
termined by simple experiment, following my
teaching that the ribs must always be su?iciently
close together that, after twisting of the bar, no
transverse plane can fail to intersect at least a
tween the ribs IS. The two series of ribs are thus
in staggered relationship. They are pitched in
the same direction around the bar. In this em
bodiment, the spacing between the transverse
ribs can be increased somewhat while maintain
portion of a rib.
,
ing the feature of increased minimum cross-sec
When the transverse ribs are arranged in the
tional area in the twisted bar. The spacing and
50
manner I have described, twisting of the bar
pitch of the ribs I18, I9 as formed by the rolling
actually increases its minimum cross-sectional
operation is so adjusted in relation to the pitch
area. _This_ may be seen from a comparison of
of the helices produced by the twisting and
Fig. 3 with any one of Figs. 4, 5, and 6. (Fig. 3 is
stretching operation that portions of ribs on op
a section of the untwisted bar.) In each case,
posite sides of the bar will be brought into com
the cross-sectional area is increased by approxi
mon
planes normal to the axis of the helices, or
mately the amount shaded for blue. Fig. 4 is
taken at the center of a rib ll opposite the web
Hi. Fig. 5 is taken half way between a rib H
and a rib 12. Fig. 6 is taken one-quarter of the
so that all planes normal to the axis of the
helices will intersect at least a portion of a trans
verse rib. In this case, the ribs I8 (and ill) may
way between a rib l l and a rib l2, i. e., half way 60 be spaced apart by a distance greater than 5/,;B
between the, two extreme or limiting conditions
represented by Figs. 4 and 5. Hence it will be
seen that these views show representative sec
tions and cover substantially all possible cases.
In every case the cross-sectional area is substan
when the helical pitch of the twisted bar is 12/1.
The spacing may be as much as %D, or more,
depending upon the initial pitch of the trans
verse ribs and to a certain extent upon the width
65 or thickness of the ribs. In every case the proper
tially increased, with resultant increase in ten
relation of initial pitch to spacing to helical pitch
can be determined by simple experiment, follow
increase has been brought about by the combina
ing, as before, my teaching that the ribs must al
tion of proper rib spacing and degree of twist
ways be su?iciently close together that, after
70
without the necessity of rolling the ribs at an
twisting of the bar, no transverse plane can fail
sile, compressive, and bending strengths.
This
angle, or on a spiral which from a manufactur
ing standpoint is not practicable.
It will further be observed that the transverse
to intersect at least a portion of a rib. I prefer
a rib spacing of not over about %D to "/8D for
all forms of bar disclosed herein, but I do not wish
ribs, while rolled initially at right angles to the
longitudinal axis of the bar, in the twisted bar 75 to be limited to this exact proportion in view of
2,405,274
6
‘the number of variables such as helical pitch,
rib thickness, etc.
ing on both sides of said web and around one side
of said rod-like sections, and a second Series Of
integral parallel transverse ribs extending on
both sides of said web and around the other side
.
The modi?ed constructions of Figs. 7 and 8 are
suggestive of certain changes which can be made
in my preferred construction while retaining
salient features of the invention. Other modifi
cations will suggest themselves to those skilled
in the art.
The terms and expressions which I have em
oftsaid rod-like sections, said two series of ribs
being arranged in staggered relationship and
being spaced closely together so that portions of
ployed are used in a descriptive and not a limit
10
ribs on opposite sides of the bar lie in common
planes normal to the axis of the helices.
5_. A rolled and twisted reinforcement bar
ing sense, and I have no intention of excluding
which comprises two rod-like sections joined by
such equivalents of the invention described, or of
an integral web, the bar being twisted about its
portions thereof, as fall within the purview of
longitudinal axis into a helical structure compris
the claims.
me: two helices having a common axis, and a series
I claim:
15 of integral parallel transverse ribs extending on
1. A method of manufacturing a reinforcement
both sides of said web and around one side of
bar which comprises the steps of forming a bar
said rod-like sections, and a second series of in
having two parallel rod-like sections joined by
tegral parallel transverse ribs extending on both
an integral web andpforming thereon a series of
parallel transverse ribs extending across said 20 sides of said web and around the other side of
said rod-like sections, said two series of ribs being
web and around one side of said rod-like sections,
arranged in staggered relationship and being
and a second series of parallel transverse ribs
spaced closely together so that all planes normal
extending across said web and around the other
to the axis of the helices intersect at least a por
side of said rod-like sections, said two series of
tion of a transverse rib.
ribs being arranged in staggered relationship, and
thereafter twisting and stretching the bar so
6. A rolled and twisted reinforcement bar
which comprises two rod-like sections joined by
an integral web, the bar being twisted about its
longitudinal axis into a helical structure compris
formed to produce a helical structure, the parallel
ribs being spaced closely together so that, in the
helical structure produced by the twisting and
ing two helices having a common axis, and a
stretching operation, all planes normal to the axis 30 series of integral parallel transverse ribs extend
of the helices will intersect at least a portion ‘of
mg across said web and around one side of said
a transverse rib.
2. A method of manufacturing a reinforcement
bar which comprises the steps of forming a bar
having two parallel rod-like sections joined by
35
rod-like sections, and a second series of integral
parallel transverse ribs extending across said web
and around the other side of said rod-like sec
tions, said two series of ribs being arranged in
an integral web and forming thereon a series of
staggered relationship and the spacing of the
parallel transverse ribs arranged at an acute
ribs being so adjusted in relation to the pitch of
angle to the longitudinal axis of the bar and ex
the helices that portions of ribs on opposite sides
tending on both sides of said web and around one
of the bar lie in common planes normal to the
side of said rod-like sections, and a second series 40 axis of the helices.
of parallel transverse ribs arranged at an acute
7. A rolled and twisted reinforcement bar
angle to the longitudinal axis of the bar and ex
which comprises two rod-like sections joined by
tending on both sides of said web and around the
an integral web, the bar being twisted about its
other side of said rod-like sections, said two series
longitudinal axis into a helical structure com
of ribs being arranged in staggered relationship,
prising two helices having a common axis, and a
and pitched in the same direction, and there
series of integral parallel transverse ribs extend
after twisting and stretching the bar so formed to
ing across said web and around one side of said
produce a helical structure, the spacing and pitch
rod-like sections, and a second series of integral
of the ribs being so adjusted in relation to the
parallel transverse ribs extending across said web
pitch of the helices produced by the twisting and 50 and around the other side of said rod-like sec
stretching operation that portions of ribs on op
tions, said two series of ribs being arranged in
posite sides of the bar will be brought into com
staggered relationship and the spacing of the
mon planes normal to the axis of the helices.
ribs being so adjusted in relation to the pitch of
3. A rolled and twisted reinforcement bar which
the helices that all planes normal to the axis of
comprises two rod-like sections joined by an in
the helices intersect at least a portion of a trans
tegral web, the bar being twisted about its longi
verse rib while planes at selected acute angles to
tudinal axis into a helical structure comprising
said axis of the helices and intermediate said ribs
two helices having a common axis, and a series of
lie wholly between the ribs.
integral parallel transverse ribs extending on
8. A method of increasing the tensile strength
both sides of said web and around at least .one 60 of a twisted reinforcement bar having two rod~
side of said rod-like sections, said ribs in the
like sections joined by an integral web, which
vicinity of the web being arranged in general at
comprises forming on the bar, prior to twisting,
an acute angle to the longitudinal axis of the bar
a series of parallel transverse ribs which are sep
and having reversely curved ends.
arated longitudinally of the bar but which are so
4. A rolled and twisted reinforcement bar ' spaced in relation to the pitch of the twist that,
which comprises two rod-like sections joined by
after twisting, portions of said ribs will be brought
an integral web, the ‘bar being twisted about its
into common planes normal to the axis of the
longitudinal axis into a helical structure com
twisted bar.
prising two helices having a common axis, and a
series of integral parallel transverse ribs extend- 70
JOSEPH D. STITES,
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