Year: 1887

page_text: We, LEWIS ROBERTS, of 18 Wall Street, GEORGE CLINTON SCOFIELD, of 72
Broadway, and JOSEPH ALLEN COULTAUS, of 49 Warren Street, all in the City and
State of New York, United States of America, Gentlemen, 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 :-
This Invention relates to the art of making Spiral Springs-Its object being to
reinforce the metal of which the spring is made instead of stretching it in the usual
manner as will be hereinafter explained.
. In order to illustrate this invention as much as it is possible, we have provided the
accompanying drawing which forms part of this specification, and in which the
invention is illustrated in various figures with similar letters of reference to indicate
corresponding parts as follows:-
Figure 1. represents a top or plan view of a spiral spring made by the old process
of stretching the wire around a mandrel or arbor.
Figure 2. represents a side elevation of the same.
Figure 3. represents a top or plan view of a spiral spring made by the new process
to be hereinafter described.
Figure 4. represents a side elevation of the same.
Figure 5. represents the feed rollers e. e. in the act of forcing the wire s. through
the guide tube n. n. into the die m.
Figure 6. is a side elevation of the die m. showing the wire s. in the act of entering
the groove f. of the same and about to travel around the mandrel or arbor d. which is
shown in cross section.
Figure 7. represents a vertical cross section through the die m. on the line a. a.
showing the spiral groove f. which forms the pitch of the spring-and
Figure 8. represents a side elevation of the mandrel or arbor d.
The process of manufacturing spiral springs, now in general use is so well known
that it seems hardly necessary to describe it in detail excepting to say that the wire is
wound around a mandrel which is a little smaller in diameter than it is intended to
have the inside diameter of the spring thus made-So that when the spring is
removed from the mandrel it will expand to about the size intended--the class of
I Drvice fid1

page_text: springs made in this manner if placed under a microscope would appear as illustrated
in figures 1. and 2. with their outside crust or periphery full of small transverse
fractures as shown at a. in each of the figures, these fractures are so great sometimes
as to be plainly visible to the naked eye even in the smallest springs and necessarily
render the spring very imperfect and liable to break without a moments notice.
The demand for perfect springs is so great that numerous persons have been seeking
to discover a method of making springs that will overcome the defects above enumerated
-and it has become an established fact that if the "crust" of the wire of which the
spring is made can be preserved the spring will be far more durable, very much more
true, and accurate and therefore much more valuable-It is also an established fact
that to stretch a wire around a mandrel to form a spring is sure to crack and fracture
its outer "crust" simply because the difference in the length of the circumferential
line of the outer diameter of the spring and the circumferential line of the mandrel
which forms its inner diameter is so great as to be about twice the thickness
of the wire of which the spring is made. Thus to overcome this difference the wire
must compress on its inner diameter or stretch on its outer surface.
It is impossible for the wire to compress on its inner diameter simply because that
portion strikes the mandrel before any strain is put on the wire and its inner diameter
is gripped to the mandrel in the form of a fulcrum and has an actual tendency to
create an additional stretching strain.
Our method of overcoming all these difficulties and defects is to force the wire of
which the spring is made within a circular die which has the same diameter as the
outside of the spring-as shown in Figures 5. and 6.-It will be very readily
understood by any person skilled in the art that a spring made in this manner will be
compressed on the inside, and that the metal which forms the spring will be reinforced
in such a manner as will compress and close up its grain or fiber instead of separating
it as is done in the stretching process-The spring made by this method therefore
will appear with the metal forming its inner diameter crowded or reinforced as shown
to a limited extent in Figures 3. and 4. by the irregular lines, c.
The manner of making springs by this improved method is illustrated in Figures 5.
and 6. which represents the two rollers e. e. revolving in the direction of the arrows
and carrying with them the wire s. which is held in line by the two guide tubes n. n.
which of course are fixtures to the machine which operates the rollers e. by this method
the wire is forced into the groove ƒ of the die m. the mandrel d. inserted within the
die as shown in Fig. 5. and revolves as fast as the wire is forced within the die-the
mandrel d. is the same diameter as it is intended to have the inside of the spring-
so that its rotary action tends to increase the reinforcement of the metal.
Having thus particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is.―
Claim 1 The art herein described of making spiral springs by forcing the wire
of which the spring is made within a circular die-thus reinforcing the said wire
substantially as described.
Claim 2 The art of manufacturing spiral springs by means of the rollers e. e. and
die m. thus reinforcing the metal of which the spring is made, as set forth.
Claim 3-The art of reinforcing the metal of which spiral springs are made, by
forcing the said metal within a circular die as described instead of stretching it as is
the usual custom.