An Improved Method of Making Dies for Forming Metal Articles.
Year: 1890

page_text: COMPLETE SPECIFICATION.
An Improved Method of Making Dies for Forming Metal Articles.
1, JOHN SCOTT, of 395 Washington Street, Taunton, in the County of Bristol and
State of Massachusetts, United States of America, gentleman, do hereby declare the
nature of my 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 manufacture or duplication of dies which are used in
making various articles of malleable metal, such as knife handles, the dies being of
hardened steel in which the desired ornamentation is formed in intaglio, so that articles
having ornamentation in relief may be formed by pressing suitable malleable metal
into said dies. Dies of this class are made by cutting the desired intaglio ornamentation
by hand in a block of steel, the cutting operation being very laborious and expensive.
Owing to the expense of making dies of this class it is very desirable to provide
cheaper duplicates of each die, so that in the event of the injury or breakage of the
original die a facsimile thereof will be available, and in case the demand for the goods
of the pattern for which the die was made is greater than can be supplied by one die,
any desired number of duplicate dies can be used simultaneously.
The only method known of duplicating said dies is by making a reverse of the die
by forcing a mass of soft steel into the original die, and subsequently hardening the
same, the article thus produced being called a "hub" and having ornamentation in
relief upon its surface like that produced on the goods made by the die, and then
forcing said hub into a block of red or white hot steel, thus forming in the latter a
facsimile of the acting surface of the die, the steel block being afterward hardened
as usual. A serious difficulty attends this method of duplication, viz.: the oxidation
of the ornamented surface of the duplicate by contact of air therewith while the
metal is hot, said oxidation causing the formation of scale on the ornamented surface
to such an extent as to seriously deface and injure the ornamentation.
My invention has for its object to prevent the formation of scale on the ornamented
or acting surface of a duplicate die formed by pressing a hub into a block of
heated steel, and it consists in protecting the said surface by a coating or film of a
suitable metal deposited by the process of electro deposition, said coating being
pressed into the block by the action of the hub and preventing the access of air to
the die surface formed on the block by the hub, as I will now proceed to describe.
Of the accompanying drawings forming a part of this specification,
Fig. 1 represents a longitudinal section of the block of steel from which a
duplicate die is to be made.
Fig. 2 represents a similar section of said block, showing the electro deposited
coating on the surface in which the die is to be formed.
Fig. 3 represents a longitudinal section showing the hub pressed into the coated
surface of the block.
Fig. 4 represents a longitudinal section of the block after the removal of the
hub.
Fig. 5 represents a section on line x, Fig. 4.
The same letters of reference indicate the same parts in all of the figures.
In the drawings
a represents a hub or, in other words, a block of steel that has been pressed into a
die formed in the usual way with intaglio ornamentation, the metal of the hub being
conformed by pressure to said ornamentation so that it presents a surface having
relief ornamentation. Said hub is made for the purpose of producing, in a block b of
hot steel, a duplicate of the original die by the pressure of the acting surface of the
hub into said block, a surface having intaglio or sunken ornamentation being thus
formed in said block.
In carrying out my invention I deposit, by a suitable electro plating process, upon the

page_text: surface of the block b into which the hub is pressed, a coating c of cobalt, nickel,
silver, or any other suitable metal capable of being deposited by electric action. Said
coating adheres closely to the surface of the steel block and is pressed into the block
by the action of the hub, the acting or die surface a' of the block being formed through
said coating, so that all parts of said die surface are protected by the coating, as shown
in Figures 4 and 5.
The block a is heated to redness or thereabouts when the hub is pressed into it, and
if the coating were not present the heated die surface a¹ would oxidize and scale
would form thereon; but the firm and intimate union of the inoxidizable coating b
with the die surface prevents the access of air to the die surface, so that there can be
no oxidation of the steel surface, the latter being therefore entirely free from scale.
The coating should be extremely thin, and in fact a mere film, so that its interposition
between the hub and the steel surface formed by the hub will not affect the ornamenta-
tion formed on the steel surface. The coating being of comparatively soft metal wears
away when the die is used, its absence causing no appreciable change in the form of
the die.
I do not limit myself to the formation of the coating b by electro deposition, as a
coating which I believe would be fairly useful may be formed by subjecting the block b
to the action of a solution of sulphate of copper, thereby forming a thin film of copper
on the surface of the block. Said solution may be applied by means of a brush, or the
block may be placed with a quantity of small motal articles, such as tacks or rivets,
in a tumbling box with a suitable quantity of the sulphate of copper solution, said box
being rotated to cause the said small articles to repeatedly strike the surfaces
of the block while the solution is in contact with said surfaces, the percussive action of
said articles having the effect of hardening the film of copper that forms on the
surfaces of the block.
I prefer the coating formed by electro deposition however, because of its firmer
union with the surface of the block and the greater protection it affords said surface.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is :
1. In the method of making duplicate dies, which consists in impressing a hub, the
surface of which is the reverse of the original die, into one of the surfaces of a block
of heated steel and subsequently hardening said block, the improved step which
consists in protecting the steel surface to be impressed, by a coating of a suitable metal
adapted to exclude air from the steel surface, as set forth.
2. The improved method of making duplicate dies herein before described, the same
consisting in depositing an electro plate coating of metal upon the surface of a steel
block, heating said block, and while it is hot impressing a male die or hub into the
coated surface, and thereby forming a die surface which is protected from oxidation
by said coating, as set forth.
Dated this 7th 1
JOHN SCOTT.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.