IMPROVEMENTS IN PROCESS OF COATING METALS
Year: 1887

page_text: ILLIAM J. WILDER,
manufacturer, a cruzen of the ited States, residing at
Ansonia, in the county of New Haven and State of Connecticut, United States of
America, do hereby declare the nature of my invention for IMPROVEMENTS IN PROCESS
OF COATING METALS and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
Similar letters of reference indicate corresponding parts in all the figures of
drawing.
Figure 1, a side view; Fig. 2, a top view; Fig. 3, a transverse section of the table
looking toward the upper end.
This invention relates to an improvement in the manufacture of metals coated with
tin-such as used for the lining of bath-tubs, refrigerators, roofing, measures, &c., and
as a substitute for tin coated sheet-copper.
Copper as a basis of sheet metal to be coated for various uses to which it is applied
is so expensive as to necessitate some resort for a cheaper material. Various alloys
have been made and coated with tin as a substitute for tinned copper-such, for
instance, as yellow-metal. Zinc has not heretofore been successfully used as such a
substitute, for the reason that in applying the hot tin to the surface to be coated the
great heat causes the zinc and tin to amalgamate to such an extent as to deface the
surface, and, further, such amalgamation destroys the life of the metal to such an
extent as to make the metal practically useless for any purposes for which tinned
sheet-copper is now employed, whereas were it not for this imperfect surface zinc
would be an acceptable substitute.
The object of my invention is to avoid this defacing of the surface, which is always
apparent in tinned sheet-zinc, as well as to avoid deterioration of the metal; and my
invention consists in coating a sheet of zinc with tin while the other surface is subjected
to a cold blast, as more fully hereinafter described.
I will first describe the apparatus by which my process may be practically
employed.
A represents the usual furnace for retaining the tin in a molten condition. Near
the furnace, and inclining toward it in the usual manner is the table B. The upper

page_text: surface of this table is constructed with numerous channels, C, having ribs D between
them. These ribs should present a narrow surface, upon which the sheet may be
placed. At one end of the table, preferably the upper end, a cold-air pipe, E, leads
to several injectors, F, one into each of the channels C. The cold-air blast is forced
through these cjectors by the common blast-fan, or any suitable device for giving
a forced supply of air, and so that the blast will be injected longitudinally through the
channels. It will be apparent that the channels may be in other than a longi-
tudinal direction, it only being essential that there shall be channels open upward
against the surface of the sheet which may be laid thereon, and so that the blast
introduced will pass into the said channels.
The sheet of zinc-say common merchantable zinc-having its surface cleaned, is
laid upon the table, and so as to cover the channels, the cleaned side uppermost. The
cold-air blast being in operation, the molten tin is flowed over the surface and quickly
wiped off. The cold-air blast prevents the heating of the zinc by the molten tin to
such an extent that no amalgamation occurs between the tin and zinc and the surface
thus tinned is as free from blemish or combination with the metal of the sheet as is the
tinned surface of the best copper.
In some cases it is desirable that the sheet shall present the appearance of copper
or other metal on the reverse or tinned side. In such a case I coat that surface with
copper, nickel, or whatever metal may be desired, by electro-deposit in the usual
manner of coating such metals. The cold-air blast prevents the heat of the sheet,
and thereby avoids oxidation or discoloration of the reverse or coated side, unavoidable
in the usual tinning apparatus where the sheet lies flat upon the table, and without
the cold blast which I have described, so that the tinned sheet coming from the table
the reverse side presents the same appearance as when laid upon the table, not being
affected by the process of tinning.
In some cases it is desirable to coat the surface to be tinned with nickel or copper,
as enabling a higher finish to the tinned surface. In this case the blast prevents the
amalgamation of the metals with the zinc as before.
The sheet thus tinned may be cold-rolled or finished in any of the usual or desirable
methods.
My improved table may be employed to great advantage in tinning pure sheet-
copper or other metals from the fact that the cold blast will prevent oxidation or
discoloration of the reverse side.
The tinned sheet-zinc being thus successfully produced, is the cheapest possible
substitute for copper, and for many purposes for which copper is used is equally as
good and for which sheet-zine as ordinarily tinned would be useless.
It will be understood that any merely formal change may be made in the practice
of my invention without departing from the spirit and scope thereof and that such
changes will be covered by the concluding claim.
I make no claim to the apparatus described.
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 herein described for tinning sheet metals, consisting in applying a
blast of cold air to the reverse side while the hot tin is being applied to the first side,
substantially as described.
Dated this 20th of T1Q7