IMPROVEMENTS IN THE MODE OF COATING METAL SHEETS OR PLATES WITH TIN LEAD OR OTHER METALS
Year: 1885

page_text: WAU AUT CHOR BRUIN, Or Amoys of the same, and
in the Apparatus to be Employed therein.
I HAMILTON HALL Merchant of 118 Bishopsgate St Within in the City of
London E.C. do hereby declare the nature of my invention for IMPROVEMENTS
IN THE MODE OF COATING METAL SHEETS OR PLATES WITH TIN LEAD OR OTHER
METALS and in what manner the same is to be performed; to be particularly
described and ascertained in and by the following statement :-
The object of my invention is to coat by one operation, plates or sheets or
surfaces of iron steel or other metals of various sizes or shapes with tin lead zinc or
other suitable metals or alloys of metals and by means of the apparatus I employ to
effect a considerable saving in the manufacture.
I have found that in passing plates of iron steel or other metal into tin terne or
other metal or alloys a certain amount of scruff undesirable matter, or impurity
adheres to the surface of the metal to be coated.
In describing this Patent I shall use the word scruff in a general sense to include
all undesirable inatter.
Hitherto great difficulty has been experienced in the attempts to remove this
Beruff etc by means of machinery.
It has further been found essential that the scruff should be removed from the
plates before they are passed between rolls otherwise the impurities become so
imbedded on the surface, that it is impossible afterwards to remove thein.
I also find that the attempts to remove the scruff etc by forcing the plate between
straight metal surfaces, or planishers, is unsuccessful owing to the plates becoming
bent and buckled from the heat of the metal or other causes, and consequently the
straight metal surface of the wiper, planisher, or scraper does not operate uniformly
on the surface of the Sheet, leaving much of it untouched. Metal or other brushes
will not stand the heat, and further get completely choked by the metal and scruff
which renders them useless-To overcome these difficulties I employ the following
meaus.
I place small pieces, pellets, grains or particles of metal (which I shall in this
Specification describe generally as pellets) either round, or of irregular shapes, in
the bottom of the pot containing the coating metal-These pellets are made of such

page_text: metals or alloys of metal which are of a greater specific gravity, and have a higher
melting point than the coating metal. In other words these pellets must be made
of metal or alloys of metal, which will not melt at the temperatures employed for
the purposes of coating, and are made of sufficiently heavy metal to sink and
remain at the bottom of the coating metal-For the selection of a suitable metal
for making the pellets I am guided by the specific gravity of the coating metal.
I do not restrict myself to any particular size for these pellets as I prefer the
sizes to be irregular.
The bulk of these pellets is regulated by the dimensions of the pot, the thickness
and size of the plate, and the amount of pressure required to remove the scruff.
Above these pellets already described and floating on or near the surface of the
coating metal, I place other pellets of metal, or other suitable substances, such as
fire clay etc, lighter than the coating metal-It is also requisite that these should
be made of metal or substances which will not melt, fuse, or be injured by the heat
of the pot.
In the operation of coating, the sheets or plates are passed into the molten metal,
and through the pellets. By this means the scruff which may have adhered to the
surface of the plate, is wiped off by the contact and friction of the pellets, which
press equally on all parts of the plate. The pressure is regulated by the bulk of
the pellets.
Besides removing the scruff, the friction of these pellets greatly facilitates and
hastens the process of coating causing the metal to be well rubbed on to the surface
of the sheet. The pellets themselves being coated and covered with the molten
metal. By this method the plates are wiped several times before they are
withdrawn from the pot, the extra labour of the washman can be dispensed with,
and the waste of metal incurred by the ordinary mode of brushing the plates is
obviated.
For some class of work, I find the pellets of great use in keeping the plates or
sheets down in the coating metal while they are undergoing the process of coating,
as they would otherwise float about in the metal. I do not confine myself, when
using this method of pellets for wiping plates, to any particular shaped pot or
machine for passing the sheets through molten metal. It can be used with the
present sides, in the Tin and Terne plate manufacture, in Galvanizing, or can be
applied advantageously to any of the machines, for coating metal sheets. Neither❤
do I confine myself to wiping and rubbing the plates in the molten metal only.
I use the pellets in the same way in conjunction with the preparing grease or
flux, to prepare the sheet before it is passed into the coating metal..
I find the friction of the pellets effectually removes the film of oxides, or
impurities, after the plate has been for a short time exposed to the action of the
preparing grease or flux. By this means the plate coats with much greater
rapidity and certainty.
I further clain a great advantage by the use of the pellets in a pot so constructed,
that the plates are made to enter in at one end, and pass out at the other such as
the pot described in Patent No 1044 of the year 1883 or any pot of somewhat the
same construction.
By filling the bottom of the pot with pellets I effectually separate the coating
metal in the pot into two distinct baths. By this method the plate is first coated
when passed into the entering half of the pot, it is then wiped free from scruff or
impurity by the friction and contact with the pellets, through which it passes. The
scruff formed in the first bath and removed froin the plate is prevented by means of
the barrier of pellets from passing into the other side of the pot or finishing bath,
which is thereby kept comparatively clean and free from scruff. The plate then
receives a second dip in purer metal.
This enables me to perform in one operation without removing the plate from
the metal bath, what is now done by skilled labour and the withdrawal of the plate
from the pot to brush it,

page_text: I also find the appearance of the plates and quality of the coating much
improved, by passing the plates through a body of pellets in the finishing grease
pot, after they have been tinned or coated in the metal bath.
By this operation I reduce the amount of metal on the plate, correct any
imperfection which may still remain, and equalize the distribution of the metal on
the surface of the plate.
I use the pellets in the grease pot, either lying at the bottom or in a box, so
constructed that the plate can pass up into the body of the pellets through an
opening on the underside of the box, but of such a width, as not to allow the
pellets to pass out. This box can be placed either under or between the finishing
rolls.
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
1. Removing the oxide, and preparing the surface of metal plates or sheets to
receive the coating metal, by passing them through a body of pellets, grains, or
small pieces of metal, or other suitable substances, while the plate is under the
chemical action of the preparing grease fluxes, or other agent used for cleaning the
surface of the metal to be coated, substantially as described.
2. Removing or wiping off from the surface of the plates, while in the coating
metal all scruff impurities or undesirable matter by causing them to pass through a
body of small pieces, pellets, or grains of toetal lying at the bottom of the coating
metal, the grains or pellets being made of metals which will not melt at the
ordinary temperatures of the metal bath, and which are heavier than the coating
metal substantially as described in my specification.
3. The use of the above described pellets made of metals or other suitable
substances lighter than the coating metal which will wipe the plates when caused
to pass through them on or near the surface of the metal bath.
4. The use of the pellets in the finishing grease bath as described, to wipe off the
surplus metal, or scruff; to equalize the metal on the surface of the plate after it
has left the coating metal.
5. The use of the pellets in the bottom of the pot, or metal bath, to form an
effectual barrier between the two ends of the pot, which, whilst permitting the
plates to pass through without emerging, impedes the passage of the scruff, or heat,
to the exit end of the bath, at the same time greatly assisting the operation of
tinning, or coating, by the friction of the pellets against the surface of the plate.
The barrier of pellets thus forming two distinct metal baths, substantially as
described.
6. The use of pellets in the metal bath for holding the plates in a certain
position under the metal during the process of coating.
.
"