Members for Bridges, Buildings, and other Structures, and in the Manufacture and. Treatment of the same.
Year: 1885

page_text: Members for Bridges, Buildings, and other Structures, and
in the Manufacture and. Treatment of the same.
I ALBERT HAMILTON EMERY of Stamford, in the County of Fairfield and State
of Connecticut, United States of America, Civil Engineer, Vice President of the
Emery Scale Company do hereby declare the nature of the said invention for
IMPROVEMENTS IN EYE LINKS OR BARS, AND SIMILAR TENSION MEMBERS FOR
BRIDGES, BUILDINGS AND OTHER STRUCTURES AND IN THE MANUFACTURE AND
TREATMENT OF THE SAME, to be as follows :—
The object of this invention is to increase the strength of those members of
bridges and other structures which are to sustain tensional strains and to increase
the tensional rigidity and strength of the whole link or member and to so much
increase the elastic strength and rigidity of the eye and parts adjacent thereto,
that these parts may not be more liable and preferably may be less liable to yield,
under strain, than the body of the link or bar which has been strengthened.
To this end such links or bars, which may be produced in any of the ordinary
modes, are under the present invention subsequently compressed between dies or
rolls, while in a cold or moderately heated state so as to permanently condense
the metal, the body of the eye link and the eye thereof being preferably compressed
at separate operations, but with the maximum pressure surface of the dies or rolls
acting on a sufficient length of the link and having such form as to prevent the
flow of metal from under such pressure surface and the consequent attenuation of
the link. For the same reason the dies by which the eyes of the link are
compressed extend to a short distance over the body of the link. While the eye
is under pressure between the dies it is expanded by forcing through it a tapering
mandrel so as to stretch the eye circumferentially beyond the limit of elasticity,
giving it a permanent set and putting the metal on the interior of the eye under
an initial strain of compression and that on the exterior under an initial strain of
tension, thus placing the metal in the most effective condition to resist the strains
to which it will be subjected in use.
The body and eye of the link having been compressed to condense the metal
and the eye stretched as above explained, the link is stretched considerably beyond

page_text: its limit of elasticity and held in this condition for a sufficient period to allow the
particles of metal to permanently assume their new relations.
The link is thus brought to its required condition and length by condensation
and stretching, each of which serves to impart a much higher limit of elasticity
and ultimate strength.
It will be apparent that if an eye bar or rod thus treated and having the metal
condensed to the greatest extent in and near the eye is subjected to a tensile
strain in excess of its elastic limit the point of minimum strength being not in or
about, the eye or at any place where the conformation of the bar or rod could
aggravate the weakness, nor on any particular line or plane, the effect of such
excessive strain, being distributed over the body, will tend to stretch and elongate
the whole body, instead of causing the bar or rod to part at a point of special
weakness. Hence it will be apparent that when a number of such bars or rods
thus treated are employed as tension members in a truss or other structure, any
such tension members which may be subjected to an excessive load by reason of
will be adapted
inequality in length or strength or straining, or from other causes,
to elongate without violence or injury until the load is equalized and distributed
among all the tension members by which it should be sustained in common.
Thus a twofold benefit results from the invention.
First, each particular bar or link bas both its elastic and its ultimate strength
much increased. Second, the whole of the parts are made to work together before
rupture of any part takes place.

page_text: Improvements in Eye Links or Bars and similar Tension
Members for Bridges. Buildings, and other Structures, and
in the Manufacture and Treatment of the same.
I ALBERT HAMILTON EMERY of Stamford in the County of Fairfield and State
of Connecticut, United States of America, Civil Engineer, Vice President of the
Emery Scale Company do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The object of this invention is to increase the strength of those members of
bridges and other structures which are to sustain tensional strains and to increase
the tensional rigidity and strength of the whole link or member and to so much
increase the elastic strength and rigidity of the eye and parts adjacent thereto,
that these parts may not be more liable and preferably may be less liable to yield,
under strain, than the body of the link or bar which has been strengthened.
To this end such links or bars which may be produced in any of the ordinary
modes, are under the present invention subsequently compressed between dies or
rolls, while in a cool or moderately heated state so as to permanently condense
the metal the body of the eye-link and eye thereof being preferably compressed at
separate operations, but with the maximum pressure surface of the dies or rolls
acting on a sufficient length of the link and having such form as to prevent the
flow of metal from under such pressure surface and the consequent attenuation of
the link.
For the same reason the dies by which the eyes of the link are compressed
extend to a short distance over the body of the link. While the eye is under
pressure between the dies it is expanded by forcing through it a tapering mandrel
so as to stretch the eye circumferentially beyond the limit of elasticity giving it
a permanent set and putting the metal on the interior of the eye under an initial
strain of compression and that on the exterior under an initial strain of tension,
thus placing the metal in the most effective condition to resist the strains to which
it will be subjected in use. The body and eye of the link having been compressed
to condense the metal and the eye stretched as above explained, the link is
stretched considerably beyond its limit of elasticity and held in this condition for
a sufficient period to allow the particles of metal to permanently assume their new
relations.
The link is thus brought to its required condition and length by condensation
and stretching, each of which serves to impart a much higher limit of elasticity
and ultimate strength.
It will be apparent that if an eye-bar or rod thus treated and having the metal
condensed to the greatest extent in and near the eye, is subjected to a tensile
strain in excess of its elastic limit, the point of minimum strength being not in or
about the eye or at any place where the conformnation of the bar or rod could
aggravate the weakness, nor on any particular line or plane, the effect of such

page_text: excessive strain, being distributed over the body, will tend to stretch and elongate
the whole body, instead of causing the bar or rod to separate at a point of special
weakness.
Hence it will be apparent that when a number of such bars or rods thus treated
are employed as tension members in a truss or other structure, any such tension
members which may be subjected to an excessive load by reason of inequality in
length or strength or straining, or from other causes will be adapted to elongate
without violence or injury until the load is equalized and distributed among all
the tension members by which it should be sustained in common.
Thus a twofold benefit results from the invention.
First, each particular bar or link has both its elastic and its ultimate strength.
much increased.
Second, the strength of the entire structure is vastly increased by securing
mutual support from all its members and preventing the excessive loading of any
separate part.
The eye-link may be forged in any usual or customary manner, but with such
reduced length that its proper permanent length will be imparted by the stretching
to which it is subjected under the improved process. The subsequent cold com-
pression and condensation, of the metal, may be produced by rolling; but the rolls
must be of large diameter and moved slowly in order that the metal may be
condensed as required and may not flow out under the pressure of the rolls, and
care must be exercised not to repeat the pressure sufficiently to render the metal
brittle. It is preferable to condense the metal by pressure between dies instead of
by rolling for the reason that in rolling the part compressed is loaded only
momentarily, while in cold pressing between dies it is retained under the load for
a considerable length of time, such sustained and continued pressure causing a
rearrangement of the particles of the metal, so that the structure permanently
assumes a more dense condition, resulting in a large increase of its limit of
elasticity and ultimate strength. Pressing between dies is preferable to rolling for
the further reason that the adjoining particles are simultaneously compressed over
a considerable area, avoiding the abrading action and violence caused by local
compression on a short or small surface, and a flow of metal from the point of
pressure which is liable to occur where the pressure surface is of small area.
In practice, dies are employed with parallel faces of considerable area where the
maximum pressure is exerted and very slightly rounded portions on each side of
the parallel maximum pressure surfaces, such reduced portions exerting a less
pressure on the metal but sufficient to imprison and prevent the ontward flow of
the metal in the part subjected to the maximum pressure. In shifting the link to
bring one section after another of its length under pressure, it is moved each
time to a less extent than the length of the maximum pressure surface so that
the dies at each pressure may overlap the part or section previously compressed.
•
The accompanying drawings illustrate dies or parts of dies and stretching
apparatus suitable for carrying the invention into effect. The power apparatus and
other necessary accessories may be of common construction.
Figure 1 is a sectional elevation of the upper and lower dies employed for
compressing the link-body showing part of an eye link or bar between them :-
Figure 2 is a plan of the lower die or table showing a portion of the eye-link or
bar in position and a horizontal section of the side dies employed to prevent the
spreading of the link or bar while under pressure. Figure 3 is a plan partly
in horizontal section, of the bed and side dies employed for confining the end of
the link or bar while being compressed, showing also the end of the link within
the dies.
Figure 4 is a vertical section of the same and of the link end therein and of the
upper annular pressure die used in connection therewith, showing in elevation the
tapering mandrel employed for stretching the eye while under pressure within
the dies-Figure 5 is an elevation of a pair of drawing heads and a link secured
therein for the final stretching operation. In Figures 1 and 2, 1 represents a

page_text: suitable bed or table and 2 a pair of dies adjustable thereon to and from each other
and in practice formed with concave faces to embrace the body of the link 4. The
link being set between the side dies 2, the latter are forced together against the
body of the link and firmly held and supported by wedge shaped followers 3.
5 is the upper or pressure die the central portion of which extending to a
sufficient length is made parallel with the surface of the bed 1 while at each side
of this central parallel surface, the surfaces recede or fall back to a very slight
extent, the curvature being scarcely perceptible on the scale on which the drawings
are made, but being much exaggerated in the drawing for the purpose of
illustration.
Any adequate machinery as for example a hydraulic press or ram is employed to
force down the upper die 5.
The formation of the bearing surface of the die is such as to give over the central
portion 50 to 50, the maximum pressure which may be for example fifty thousand
pounds to the square inch while the pressure from 50 to 5b may be forty thousand
pounds to the square inch, from 5 to 5° thirty thousand pounds, from 5° to 5d
twenty thousand pounds and from 5d to 50 ten thousand pounds, for example, thus
tapering off gradually. so as to avoid any violence or abraiding of the metal, while
each zone of pressure effectually prevents outward flow of metal from the adjoining
zone of greater pressure and the zones of gradually reduced pressure from 50 to 5º
effectually imprison the metal subjected to the maximum pressure between the
points 5 and 5.
Supposing the portion of the die from 5 to 5a to be thirty inches long and the
part from 50 to 5° at each end to be five inches, the link may be shifted after each
operation twenty five inches so that there will be an overlap of five inches in the
successive maximum pressure surfaces, and the portion of metal subjected to the
maximum pressure will be at each operation imprisoned by the pressure of
the slightly curved and receding surfaces from 50 to 50 on the fresh metal at the
advancing end of the die. The pressure at each operation is maintained steadily
for a considerable period so as to permit the particles of metal to permanently
assume their new relations. The entire body of the link having in this manner
been compressed while in a cold or moderately heated state the successive ends or
the eyes 6 thereof are in like manner compressed by placing them on bed dies 7,
Figures 3 and 4 forcing against their sides concave faced side-dies 8, pressed up
and held by followers 3a and then bringing down the top die 10 Figure 4 to
compress and condense the metal. These dies for condensing the eye ends of the
link are formed to extend for a short distance over the body of the link and, as
already described with reference to the top dies 5 are formed with very slightly
receding faces from 10% to 10e so as to prevent violence to the metal and prevent
the outward flow of metal from the portion subjected to the maximum pressure.
The dies for compressing the eyes or ends of the links are of annular form giving
access to the interior of the eye in order to permit the insertion and pressing
through the eye of a tapering mandrel 11, the outward pressure of which while
the eye is in a cold or moderately heated state and confined on all sides by the
dies 7, 8, 10 condenses the metal by radial pressure from the interior outward
stretching the entire eye and subjecting the metal on the inner part of the eye to
initial strains of compression and that on the exterior to initial strains of tension.
This load of compression is maintained as already described in reference to the
body of the link for a sufficient period to permit the particles of metal to
permanently assume their new conditions and relations.
The dies 5 and 10 may if preferred be divided as illustrated in figure 1 so that
the outer portions 5f figure 1 and from 10 to 100 figure 4 can be operated by a
separate hydraulic press applying the confining pressure to the adjacent parts of
the link before the maximum condensing pressure is applied by the die 5 or 10.
The entire eye-link having in this manner been subjected to compression while
in a cold or moderately heated state, the link is next stretched considerably beyond

page_text: its limit of elasticity, so as to impart a permanent set with increased length, the
increase being in many instances from two to five per cent or even more.
This stretching of the link is effected by any suitable apparatus, as for example
drawing heads 12, 12 (Figure 5) connected to hydraulic jacks or other adequate
power.
The eye may be polished after the stretching of its body by a second mandrel; to
bring it to size and to circular shape or by reaming or broaching.
It frequently happens that the most advantageous stretching of the link will
result in imparting a set to the eye. In this case the final finishing of the eye is
deferred until after stretching.
The term "moderately heated" in this specification refers to such heating as
does not change the texture of the iron or steel and temporarily render it plastic.
While it is the intention to treat the metal in a substantially cold state, it is
evident that heating it to a moderate extent, up to 300° Fahrenheit for example or
even more, so long as it is not rendered plastic would not change the novel process
nor involve any departure from the invention; but any heat which would disturb
the crystallization or relax the condensation to which the metal has been subjected,
or prevent the condensation of the metal would defeat the object of the invention.
Heating even to such a degree as to show color would prevent or impair the effects
to be produced, as the metal would not then acquire the increased limit of elasticity
or condensation desired.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The process of strengthening eye-bars and like tension members of bridges
trusses and other structures which consists in compressing the body of the bar
while cold or nearly so between dies formed as herein described, to confine the
metal subjected to maximum pressure by the application of reduced pressure to
the metal on either side of it as explained.
2. The process of treating eye-links or bars to increase their strength which
consists in compressing the eyes while in a cold state or nearly so, between dies
formed as herein described preventing the flow of metal from the part subjected to
maximum pressure by the application of reduced pressure to the adjacent parts.
3. The process of treating eye-links or bars to increase their strength which
consists in compressing the eyes subsequently to forming them by the ordinary
method, and when in a cold or moderately heated state between dies extending
partly over the body of the link.
4. The process of treating eye links or bars to increase their strength and
limit of elasticity which consists in pressing the eye from the interior outward
subsequently to forming it by the ordinary method, and while in a cold or
moderately heated state, so as to put the metal under an initial strain of compression
on the interior and tension on the exterior.
5. The mode and process of increasing the strength and limit of elasticity of eye-
links or bars, and like members which are required to endure tensional strains in
bridges trusses and other similar structures, the same consisting in stretching each
separate link or bar permanently to a considerably increased length, while in a cold
or moderately heated state, subsequently to forging.
6. The mode or process of increasing the strength and limit of elasticity, of eye-
links and bars and like members, which are required to endure tensional strains in
bridges trusses and other similar structures, the same consisting in stretching each
separate link or bar and holding it for a considerable period under tension sufficient
to impart a considerable permanent increase in length.
7. The process of manufacturing and treating eye-links or bars which consists in
forging the bar and eyes in any customary or suitable manner and after the same
is completed for use as ordinarily made and when cold or nearly so compressing the

page_text: links or bars or portions thereof between dies or rolls compressing the eyes from
the interior outward and stretching the links or bars beyond the limit of elasticity
so as to impart a permanent set with considerable increase of length.
8. An eye link or eye bar forged in any usual or suitable manner and subsequently
strengthened by cold compression, especially at and near the eye.
9. An eye link or eye bar forged in any usual or suitable manner and subsequently
strengthened by stretching the metal around the eyes so as to produce initial strains
of compression on the interior and tension on the exterior, as explained.
10. An eye link or eye bar forged in any usual or suitable manner and
subsequently stretched to its required length while cold or nearly so, so as to impart
a permanent set as explained.