Year: 1888

page_text: Date of Application (in United Kingdom), 29th Sept., 1888
Complete Specification Left, 29th Sept., 1888
Complete Specification Accepted, 12th Feb., 1889
I HENRY HAZLETT FORSYTH of Pittsburg Pennsylvania United States of America
Gentleman 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 :-
My invention relates to an improvement in dies for forging or swaging pieces of
iron or steel which are of circular cross-section and either of cylindrical conical or
irregular longitudinal section. Heretofore it has been the practice in forming such
articles to use two dies of similar contour, the edges of the working cavities of which
come into contact in the operation of the dies. The article to be forged-for example
a piston-rod, an axle, or the like is placed on the lower die, and the upper die or
hammer is caused to beat upon it, the iron meanwhile being turned on the bed-die.
The difficulty in the use of these dies is that when the conjoined cavities are circular
in cross-section they are apt to form fins on the surface of the article. This has
caused manufacturers generally to employ dies with elliptical working cavities, so
made in order to avoid the formation of fins: but the use of the elliptical dies is
disadvantageous in that it is hard to produce by the articles of uniform circular
cross-section and in any case the contact of the dies batters the edges of the cavities
and soon impairs their efficiency where great accuracy of outline and smoothness of
surface are required.
The object of my invention is to cure this defect and to provide dies by whose use a
perfectly round and uniform article can be produced.
In the accompanying drawings Figure 1 is a vertical cross section of my improved
dies shown in conjunction. Fig. 2 is a plan view of the lower die. Fig. 3 is a

page_text: plan view of the lower die modihed in order to adapt it to the manufacture of tapered
articles. Fig. 4 is a vertical sectional view similar to Fig. 1 illustrating a modified
form of the dies.
Like symbols of reference indicate like parts in each.
Referring now to the drawings, 2 represents the upper die, and 3 the lower die.
The working-face 4 of the lower die is made with a curved contour on the arc of a
circle, the curve being preferably nearly semicircular in cross-section and from the
top of the semicircle the bottom die extends upwardly and outwardly in flaring lines 5.
The working face of the upper die 2 is also made with a curved contour whose cross-
section is that of the arc of a circle somewhat less than a semicircle. The edges of
the cavities of the dies are separated by recesses 11 which communicate with
the cavities and while not substantially impairing the general circular shape in
cross-section of the conjoined cavities, yet part the edges and prevent the formation.
of fins on the article. From the extremites of the cavity 6 of the lower die the body
of the die extends upwardly and outwardly on diverging lines 7. These cavities need
not be continuously arcs of a circle, for they may be made ridged or polygonal; but
it will be found that the nearer the approximation to the circle the better will be
their operation.
In order that the faces of the dies shall not meet in their work of hammering 1
provide them with shoulders 8, 9, at their outer sides, which shoulders meet when
the moving die is in action, and by receiving the impact of the blows prevent the
working-faces of the dies from coming into contact and from being injured. In
order to save these shoulders from injury as much as possible, I prefer to face the
shoulders 9 with plates 10 of copper, or some other soft metal, which are set in
recesses on top of the shoulders, and by opposing a soft body to the action of the
moving upper die serve as buffers. Instead of having. these shoulders 8 and 9 in
connection with the bodies of the dies, I may substitute therefore suitable stops on
the plunger or the slide or piston-rod, which will act in substantially the same way to
produce the same result.
The operation of the dies is as follows-In order to forge a bar of iron into the
proper cylindrical shape, supposing the die-cavities to be constant in cross-section, the
bar is laid on the inclined faces 5. of the lower die, 3, and the upper die, being
actuated by a suitable steam hammer or plunger worked by a cam or crank, is caused
to reciprocate and to impart its blows to the bar. The bar is turned by a workman
or by suitable machinery continually during this operation, and the effect of the upper
die, acting in conjunction with the inclined faces 5, is gradually to diminish the
diameter of the bar and to bring it more nearly to a circular form, and finally to
force it into the cavity of the lower die, which, in conjunction with the correspondingly-
curved cavity of the upper die, gives the bar its finished circular form. I am enabled
thus to successfully employ dies the general contour of the cross-section of whose
conjoined working-cavities when the dies are most nearly in contact is substantially
circular, to conform to the section of the finished article, the conjoined cavities having
parted or recessed sides, and thus I get alantages of the circular dies with-
out the disadvantages which have heretofore attended their use. This I am enabled
to do by reason of the use of the inclined side faces 5 and by reason of the fact that
the working-faces of the dies do not come in contact at the edges. If they should
come in contact the effect would be to flatten out the metal bar, to produce fins on it.
and to spoil the dies without attaining the desired result. I believe that I am the
first to dissociate the edges of the operative faces of the dies from the stop which
limits their approach. This is a very important feature of my invention, since it
enables me to make the articles of true circular form in cross-section, and also to
prevent the dies from becoming battered or misshapen. In case the article to be pro-
duced is not of cylindrical but is of tapering form-such as a wagon axle-the
operation is the same, except that the dies, instead of having working-faces with
cavities of constant width, have cavities conforming to the shape of the article,
as shown in Fig. 3. For producing articles of other forms in longitudinal
section the dies are correspondingly modified, as will be readily understood,

page_text: My invention is susceptible of many modifications, not only in change of shape of
the dies to correspond to the change in shape of the article produced, but also in
other changes of form of the parts. For instance, the recesses 11 at the sides of the
working cavities of the dies are solely for the purpose of preventing contact of the
working-faces and may be greatly modified in form, and instead of having the dies
arranged as shown in the drawings they may be reversed, the present lower die being
used as the upper die, and vice versa.
illustrate a modification in form of the recesses in Fig. 4 in which the inclined
faces 5 and 7 of the dies are not used and the recesses 11 are enlarged. Other modi-
fications will suggest themselves to those skilled in the art.
My invention is of great practical utility and will be appreciated by those skilled in
the art.
It may be used not only for the purpose of forging hot metals into the
proper shapes but for finishing articles by cold-hammering. This last named feature
makes it especially desirable in the manufacture of tapered iron axles and other articles
of irregular longitudinal section. Hammering by means of these dies preserves the
desirable hardness of the article.
I do not claim herein, broadly, dies having their working-faces provided with semi-
circular cavities, nor do I limit the scope of my claims to dies having working-cavities
made on the arcs of a circle, unless expressly so stated therein, since, if the stops be
used, the working-cavities of the dies may be otherwise shaped, ny invention in this
regard relating to the construction of the dics by which the edges of the cavities are
prevented from coming into contact, and by which 1 an enabled, if desired to use dies
the general contour of whose conjoined working cavities is substantially circular in
cross-section.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what 1
claim is,
First. An improvement in dies for forging or swaging, which consists in the com-
bination of dies whose opposing faces are provided with suitable working-cavities
made substantially in arcs of a circle, the general contour of the conjoined die-cavities
when the dies are most nearly together being substantially circular, the edges of the
cavities of the dies being separated by lateral recesses, substantially as and for the
purposes described.
Second. An improvement in dies for forging or swaging, straight metal articles,
which consists in the combination of dies whose opposing faces are suitably formed
and stops whereby the motion of the movable die is limited and the edges of the
working-faces are prevented from coming into contact, substantially as and for the
purposes described..
Third. An improvement in dies for forging or swaging straight metal articles
circular in cross-section and either of constant or varying longitudinal section, which
consists in the combination of dies whose opposing faces are provided with cavities,
the cavity of one of the dies having flaring extensions substantially as and for the
purposes described.