Improvements in or relating to Moulds for Moulding or Pressing Wood or the like.
Year: 1896

page_text: Date of Application, 6th June, 1896
Complete Specification Left, 6th Mar., 1897-Accepted, 10th Apr., 1897
PROVISIONAL SPECIFICATION.
Improvements in or relating to Moulds for Moulding or Pressing
Wood or the like.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I. Mech. E., of 6 Lord Street,
Liverpool, and 322 High Holborn, London, Patent Agent for Engraved Wood
Limited, do hereby declare the nature of this invention to be as follows:-
Hitherto moulds for this purpose have been made of cast steel engraved out for
the purpose and consequently are exceedingly expensive. Now this invention is
designed to make cheap moulds and at the same time to form moulds giving a
higher relief and also be able to form curved ornamental surfaces.
I first of all form a box of the very strongest and toughest steel planed on both
sides. The interior of the box is roughened in any desirable manner such as for
instance having numerous studs in the bottom or projecting ribs or points. Into
this box hard type metal or other hard easily fusible composition made preferably
of tin, lead, antimony, bismuth and aluminium, and in some cases a little zinc,
copper, cadmium, or mercury is added. This alloy is so proportioned as to expand
slightly on cooling and at the same time be sufficiently hard and tough to resist a
pressure. Congealing round the various studs in the bottom of the metal it is
prevented from falling out of the steel mould. In casting the pattern I form a
pattern first of wood plaster or other material and in some instances electroplate it.
I then place the electroplate or naked mould or pattern in the sand at the right
height and place the steel box inverted over it, then run the fusible metal in
through a high gate and allow it to cool. It is then stripped from the matrix and
in some instances an even coating of a hard metal electroplated on it in the same
way that copper engravings are sometimes coated with steel or hard metal.
Hitherto a mould has been placed in the press the wood placed upon it, and the
pressure effected. By this means however we cannot get a great height of relief.
In order to get a higher relief I form a second mould the complement of this mould
but where only one side of the moulded wood appears this latter mould can be only
a very rough casting. The two mould frames have pins and holes placed in their
outer rims so as to exactly register one with the other. A piece of wood is now
placed upon one mould inside the pins and the second mould applied and the whole
placed in the press. When it is desired to form curved impressed pieces such as
the back of a chair the wood is steamed and bent to the right curve. The mould
is then made to the same curve and the wood engraved by hydraulic pressure in
the manner well known. For door panels I prefer to form two different patterns
in the two moulds so arranged that the maximum relief on the one mould will
roughly correspond to a maximum hollow in the other mould and vice versa. It is
not necessary that the two moulds should be exactly alike but simply that nowhere
shall two high reliefs come opposite each other.
Dated the 5th day of June 1806
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Patent Agents for the Applicant.

page_text: for pouring in the metal.
Fig. 5 the same box without its lid being used in combination with the pattern
as an electrolytic bath.
Figs. 6 and 7 a plan view and a section of a double die used for impressing chair
backs.
Referring first to Figs. 1 and 2, A is the cast iron box drawn to scale and
- usually about one and a half inches thick. B the pouring hole. Ca high funnel
or gate. D two little air holes about three-sixteenths of an inch in diameter for
the escape of air. In Figs. 3 and 4 the same letters refer to the same parts but
there is an additional part E forming the bottom or lid of the box. F is the
pattern of wood or plaster of Paris either naked or clothed with electro-type
matter as hereafter described. H (Fig. 5) are cathode wires in electrical connection
with a thin coating of graphite and beeswax or other simple electrical conducting
coating on the pattern F. Between the box and pattern F is also placed a thin
layer of waterproof cement or wax, vaseline, or the like to form a joint & prevent
the escape of electrolyte. I are the anode wires and J the anode hereafter
described. In Figs. 6 and 7 A & A are two moulds, or dies male and female
and K a fence preferably on the bottom mould firmly attached to the end. The
upper mould is then pressed against this fence when put in the press so as to
exactly register. In place of this fence a stout pin or peg at each end can project
from the bottom mould and enter a corresponding hole in the upper die. I prefer
however the fence above described. The mode of action is as follows:-I form
the box A and the lid E (if there be one) of tough cast iron or other like tough
hard metal. The interior of the box cau be roughened somewhat in order to
enable the type metal to stick or it can be tinned. The type metal however
generally sticks quite tight enough without any special preparation of the surface.
Where a die is only required to make a comparatively few repeats and will then
no longer be required, but can be broken up, I simply place the pattern with the
required design in wood plaster or the like thoroughly desiccated against the
planed and open side of the box Figs. 1 & 2 and clamp it tight. I then place it
on end, preferably heat it considerably above the boiling point of water and then
pour in the type metal rapidly and with a high gate until it is full. The type
metal sometimes flows out of the air holes, but generally congeals in them. When

page_text: the gate is full up to the top it is well just to smartly strike the back of the mould
with a hammer and then knock off the gate. The hole or holes are then filled up
with type metal. Where however a very large number of repeats are required
I prefer to coat the pattern first electrolytically with a very thin layer of copper.
On this thin layer of copper I then deposit a harder metal say iron by using an iron
anode and an electrolyte formed of a saturated solution of protosulphate of iron
and chloride of ammonium in equal quantities and then add about twice its weight
of water. It is not at all a bad arrangement to use the box itself as an
electrolytic bath and Fig. 5 shows this arrangement. The pattern is thoroughly
well coated with blacklead and oil or beeswax. A sulphate of copper solution is
first put in and a copper anode placed above & connected up and a thin coating of
copper deposit, the copper solution is then withdrawn and the iron solution inserted
with an iron anode until a layer of something under a millimetre in thickness has
been formed. I then withdraw the electrolyte the anode and the wires, place the
lid on the box clamp the whole together, place it on end and pour in type metal or
stereotype metal or other suitable filling until the box is full as above described.
It is needless to say that both faces of the box must be planed and if a lid be used
the lid also must have its flange and back planed. In some instances however I
may simply use a temporary or permanent back as a simple plate of iron clamped
on and then fill the entire mould with type metal. This is cheaper than having a
planed back, but is not always so effective as there is more liability to blow holes
and other defects when there is a great thickness of type metal than when there is
only a comparatively thin layer. In Fig. 6 I show a pair of dies for making chair
backs and other curved surfaces. In this instance the wood if the curve is not too
great is simply placed in the die and the die pressed down till it presses the wood
to its right shape but where the bend is otherwise too great the dies are heated
and gradually applied, the wood being pressed in a comparatively damp state.
speaking of type metal in the foregoing the very hardest type metal is preferably
used, the mixtures of metal which I prefer being 70 per cent. lead, 24 per cent.
antimony, 2 per cent. tin, 1 per cent. arsenic, and 2 per cent. bismuth. Besides these
a small amount of nickel and of copper is also desirable, but the nickel and copper
must be first melted and the tin added and then the united metals poured into the
liquid type metal. The arsenic should be added just before pouring. In some
instances when an ordinary type metal die has been made I may electroplate its
surface with a very thin coating of iron or other hard material as is done in
ordinary copper-plate engraving. This enables the mould to last much longer and
prevents it from blackening portions of the wood which it otherwise sometimes
does. In making purely type metal moulds it is desirable not to have high
projecting points or even ridges of type metal unsupported. Where such are in
the pattern it is always best to electroplate before casting. I have only mentioned
copper and iron, but it is obvious that nickel and other metals can also be used.
In making door panels and the like where both sides of the panel can be seen it is
desirable to have two moulds and it is not always necessary that the same pattern
should be on both moulds so long as it is arranged that no high relief on one side
of the panel is opposite a high relief on the other side. There is a great advantage
in any case of using two moulds a male and female as when this is done the great
tendency to become convex on the pattern side is thus obviated.
In
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. A composite die for use in wood pressing formed of type metal or the like
encased in iron or other stronger and tougher metal substantially as described.
2. The mode of forming dies which consists in placing an iron or other like
box with its hollow side against the pattern and filling the space between with type
metal or other metal which does not contract sensibly on setting and whether the
pattern be electroplated or be an electrotype film or a naked pattern.

page_text: 3. In the process of making pressed wood carvings in which there is a thick
layer of wood with the grain on end enclosed in layers of veneer the combination
of a male and female die guided so as to register one with another whereby a
higher relief can be obtained than when only one die is used and the panels are not
so liable to warp.
4. The process of making pressed wood chair backs and other curved articles
which consists in having a male and female die curved to the required shape and
with the required ornamental pattern and pressing the same gradually with or
without heat and moisture.
Dated the 5th day of March 1897.
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Patent Agents for the Applicant.