Year: 1886

page_text: Date of Application, 20th July, 1886.
Complete Left, 16th Apr., 1887.
Complete Accepted, 17th May, 1887.
declare the nature of this invention to be as follows:-
My invention consists in a process of straightening and stiffening metal bars by
subjecting them to a powerful longitudinal tension so as to pull straight any curves
or crooks existing in them, and also to give them a permanent elongation and set in a
straight line.
Bars thus elongated, straightened and stiffened by tension, are more useful for
many purposes and are more suitable for being afterwards turned, planed or ground,
or drawn through dies or elongated by rollers.
One part of my invention is to combine the action of the longitudinal tension with
a simultaneous compression of the surface of the bar by means of dies or rollers.
The effect of this is that the bar, besides being stretched and straightened by the
first application of the tension, is also kept in a state of extreme elastic elongation
continuously while it is being compressed by the dies or rollers, so that the flow of
metal caused by the compression takes place in the line of the elastic elongation, and
additional permanent elongation, set and stiffness are obtained. Bars thus elastically
elongated by tension require less force to pull them through a die, and the pressure
on the die hole and its consequent wear are less. Bars of large sectional area which
would be difficult to draw through dies in the ordinary way can conveniently be
drawn by this combined action.
Bars drawn or rolled while elastically elongated have less inequality of strain
between their outer and inner portions than is the case with bars drawn or rolled in
the ordinary way. When round bars are treated by rollers, either after or during
the application of the longitudinal tension, the rollers may either be made to revolve
in planes passing through the axis of the bar, as in the ordinary rolling process, or
the rollers may be placed in a frame which is made to revolve round the bar and also
to traverse it lengthways, so that the rollers will run round the bar, revolving in
planes perpendicular, or nearly so, to its axis, and will make spiral lines of compressed
surface round it, from one end to the other.

page_text: Before being subjected to the tension the bars should be well annealed so as to avoid
any difference of hardness or elasticity in the metal on different sides, which would
tend to make the elongated bar curve itself after the tension is relieved.
Such curves however are long and regular and can be straightened by ordinary
methods. Hydraulic apparatus provided with accumulators having adjustable loads is
a convenient means of applying a regulated degree of tension particularly to bars of
considerable sectional area.
Shafting, rails for railways, beams, girders, tension rods and generally metal bars
which are desired to be stiff and resistant to strains may be advantageously treated by
longitudinal tension, which may or may not be combined with surface compression
from dies or rollers. I generally apply the tension to bars at the ordinary temper-
ature of the air. Heat will make the metal more ductile, but should not exceed the
temperature of melting lead or thereabouts.
ALLISON BROS.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Straightening, Stiffening, Drawing, and Rolling
Metal Bars.
I, BENJAMIN CHEW TILGHMAN of Altrincham in the County of Chester Engineer,
do hereby declare the nature of my invention for IMPROVEMENTS IN STRAIGHTENING
STIFFENING DRAWING AND ROLLING METAL BARS and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
My invention consists in a process for straightening, stiffening, drawing and rolling
metal bars by subjecting them to a powerful longitudinal tension at the same time
that they are receiving a compression of their surfaces by the action of dies or rollers.
The effect of this combined action is that the bar is first straightened and to some
extent elongated by the tension and is also kept in a state of extreme elastic elongation,
so that the coinpressive action of the die or rollers applied consecutively upon each
point of the surface causes the final change of shape and makes the flow of metal take
place more readily in the line of the elastic elongation and gives greater straightness
and stiffness to the bar.
Bars drawn while thus elastically elongated by tension require less force to pull
them through a die and the pressure on the sides of the die hole and its consequent
wear are less-Bars of large sectional area which would be difficult to draw through

page_text: a die in the ordinary way can more conveniently be drawn by this combined action.
The longitudinal tension strains the bar nearly up to its yielding point, and the
surface compression then has less work to do in reducing the diameter and increasing
the length of the bar.
The surface compression acts directly to lessen the diameter of the bar but only
indirectly to increase its length, and in the same way the longitudinal tension acts
directly to increase the length but only indirectly to lessen the diameter, but when
the two forces are applied at the same time each supplies the deficiency of the other.
Bars drawn or rolled while elastically elongated by tension have less inequality of
strain between their outer and inner portions than is the case with bars drawn or rolled
in the ordinary way.
It is to be understood that the tension which gives the elastic elongation to the bar
is independent of, and additional to, the force which pulls it through the die; the
latter acts only on that part of the bar which has passed through the die, the former
acts on its whole length.
Before being subjected to the combined tension and compression the bars should be
well annealed so as to avoid any difference of hardness or elasticity in the metal on
different sides which would tend to make the elongated bar curve itself after the
tension is removed.
Such curves however are generally long and regular and can be straightened by
ordinary methods.
The following is a method of carrying my invention into effect taking for example
the application of longitudinal tension to a bar at the same time that a die is being
drawn over it. Referring to the drawings Fig. 1. is a horizontal or plan view, partly
in section, and Fig. 2. is a vertical sectional view on the line ay of Fig. 1.
A is a hydraulic press constructed so as to pull by the rod B and having a stroke
longer than the greatest elongation intended to be given to the bar. C C are two
long hydraulic presses which also serve as columns to take the thrust between the
press A and the cross head D.
The plungers E E have a stroke longer than the longest bar intended to be treated.
The cross head F, rigidly connecting the plungers EE, runs in ways G G, and is
connected by rods H H with the moveable die head i, which also runs in ways. All
these ways and the lines of motion of the plungers of the three presses and of the
cross head F and the die head i are parallel to each other. The bar K having been
previously annealed is to have its scale removed in the usual way, and both its ends
are to be reduced concentrically in diameter so that the die M will slide over them.
One end of K is passed through the die M and the die head i and is gripped fast
in the cross head D, and its other end is gripped in the collar which is fastened to the
rod B, the bar K being adjusted so that its axis is parallel to the line of motion of
the die head i. Tension is then applied by means of the press A until the curves of
the bar have been pulled straight, and it is stretched nearly or about up to the limits
of elasticity, or it may be permanently elongated to a slight extent.
The plungers E E are then set in motion with equal speed and pressure and the
die M is drawn over the bar until it reaches the part at the other end where the
diameter is reduced. The plunger of the press A is then drawn back so as to
allow the gripping wedges to be removed and the bar is taken out. The plungers of
the three presses and the die head are then drawn back to their original positions by
counterweights.
When the length of the bars treated is considerable their weight and that of the
long plungers and connecting rods may be supported by pivoted levers arranged so as
to allow of the passage of the cross heads, as is well understood.
The hydraulic pressure in the press A is continuous during the passage of the die,
so that the elastic tension is kept constant on the bar K, notwithstanding its elongation
by the drawing process. Hydraulic accumulators, the loads of which can be adjusted
to suit, are convenient to work the presses so as to give a regulated tension. They
are well understood and need not be described.
The amount of longitudinal tension to be applied will vary with the sectional area

page_text: of the bar and the nature of the metal and may be described approximately as about
the elastic limit of the bar. It should be great enough to pull straight the curves of
the bar, and may also give it some permanent elongation, and it should not be great
enough to reduce its diameter in any place to the diameter of the small end of the
die hole.
The longitudinal tension should do a large part of the work but the final shape of
the bar should be given by the compressive action of the die.
Although I recommend that to produce the best result the longitudinal tension
should be great enough to pull straight all the curves of the bar, yet a less degree of
tension will produce partial effects in improving the straightness and stiffness of the
bar, and facilitating the action of the die and may be practically sufficient in some
cases. I have described a hydraulic machine because I think it most convenient
especially for drawing rods of considerable sectional area, but it is evident that the
invention can be carried out by any machine operated by steam cylinders, screws,
drag chains or otherwise, and capable of giving the requisite tension to the bar, and
the pull to the die. I do not claim or confine myself to the machinery herein described
or any particular form of machinery-The invention may be applied to bars and rods
of any shape or cross section capable of being drawn or rolled. In carrying my
invention into effect I prefer to apply the surface compression by means of dies
because great accuracy of shape can thus be obtained, but it may be applied also by
means of rollers in combination with longitudinal tension.
The rollers may be made to rotate in planes passing through the axis of the bars, as
in the ordinary rolling process. Or, in the case of round bars, the rollers may be
placed in a frame which is made to revolve round the bar and also to traverse it
lengthways, so that the rollers will rotate in planes perpendicular or nearly so to the
axis of the bar, and will make spiral lines of compressed surface round the bar from
one end to the other-These arrangements are well understood by engineers, and need
not be particularly described.
Any known method or machine for rolling bars may be used to give the surface
compression at the same time that the longitudinal tension is applied according to my
invention. I generally prefer to work my invention at the average temperature of
the air. A moderate degree of heat, never exceeding that of melting lead may be
useful in some cases to make the metal more ductile.
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,
The process of drawing or rolling metal bars by the application of longitudinal
tension throughout the whole length of the bars simultaneously with and in addition
to the compression of their surfaces by the action of dies or rollers.
Dated this Twelfth day of April 1887.