IMPROVEMENTS IN AND IN MACHINERY FOR DRYING AND PRESSING BOARDS AND VENEERS
Year: 1880

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
AND IN MACHINERY FOR DRYING AND PRESSING BOARDS AND VENEERS."
A. communication from abroad by George Washington Read, of New York
City, United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 22nd July 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN AND IN MACHINERY FOR DRYING AND
PRESSING BOARDS AND VENEERS." [A communication from abroad by George
Washington Read, of New York City, United States of America.]
The object of this Invention is to perfectly and rapidly season boards and
veneers by a process of air and press drying, and to flatten or curve the same
during the seasoning process. For this purpose I employ a number of hollow
steam heated pressing plates or platens superposed between the ram or rams and
crosshead of a hydraulic press, and supported when not in operation by the columns
of the press at any required distances apart to permit of the work being introduced
between them, and which are capable of being raised from their supports and closed
upon the work by pressure between the rams and the crosshead.
To the interior of these hollow platens steam is conveyed from a steam distributing
chamber through separate pipes connected to the respective platens, and which
have longitudinal motion through stuffing boxes or glands in the top of the
distributing chamber to enable the platens to be closed together with the work
between them. A constant circulation and regular degree of heat is maintained by
providing similar pipes and connections at the opposite end of the platens, the
steam or condensation communicating through check valves to the air, or returned
to the steam generator. The broad top and bottom surfaces of these platens are
planed perfectly smooth and flat, and have at frequent intervals grooves cut
transversely across their faces from edge to edge. The direction and number of
grooves may be regulated according to the work to be done. On the planed and

page_text: grooved surfaces of the platens are fastened thin face plates of brass or other
material of good conducting quality, having at frequent intervals minute perforations
extending through their thickness and leading into grooves in their sides next to
the platens corresponding with the grooves in the surfaces of the platens, and
forming, by coming opposite thereto, tubular channels for the escape of the vaporised
moisture from the wood. Between the perforated face plates of these platens are
placed the boards or veneers to be seasoned and pressed, care being taken to cover
the whole surface of the platens as nearly as possible when they are closed upon
the material by hydraulic power operating through the rams, to which water is
conveyed from an accumulator. For rough material the grooved platens may be
used without the face plates, but for comparatively smooth surfaces where finish is
required it is preferred to use the perforated face linings. While the material is
under pressure of the heated surfaces the moisture finds free escape through the
perforations and channels provided for the purpose. When the material is dry,
and just before taking it out of the press, additional pressure may be given to
remove any slight irregularities in thickness, and to give a more highly finished
surface. When this is accomplished the water is released from the rams by a
suitable valve and the platens drop, each one to its former place, to enable the dried
and pressed material to be removed and other material inserted.
While the press
is being filled again the material taken out is allowed to cool before being laid
together.
The whole operation is simple, and the result is a great saving of time, labor,
and expense. The same method may be employed in bending boards and veneers
to curved or irregular shapes by giving the surfaces of the platens the desired
curvature or form.
Instead of driving the press rams directly from the hydraulic pump I employ an
accumulator constructed of two or more stand pipes, in which power is stored by
pumping in water against the pressure of compressed air confined at the upper
part of the stand pipes, which are connected by pipes and check valves. These
stand pipes are of lap welded iron of internal diameter and height according to the
number of presses to be operated, to which the accumulator is connected by suitable
pipes and controlling valves.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Creat Seal Patent Office on the 22nd
January 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN AND IN MACHINERY FOR DRYING AND
PRESSING BOARDS AND VENEERS." A communication from abroad by George
Washington Read, of New York City, United States of America.
This Invention relates to a process of and machinery for air drying and pressing
boards and veneers under heat, whereby they are perfectly and rapidly seasoned and
their surfaces finished or smoothed, and they are at same time flattened or curved
as may be required, the said process and machinery being adapted to all sawn boards
of moderate thickness and veneers, but more especially to boards and veneers cut
from the log by means of a knife.
In order that the Invention may be more fully understood, I will proceed to
describe it with reference to the accompanying Drawings, in which Figure 1 is a
front, and Figure 2 an end elevation of the improved press for drying and
seasoning boards and veneers. Figure 3 is a horizontal section of the same just
above the rams. Figures 4 and 5 show details.
A is the base plate, B the follower, C the columns, D the rams, and E the head of
the press. B¹ are pressing plates or platens, between which the boards or veneers
are placed to be pressed, and which, as well as the follower B, are hollow and of
suitable construction and strength. They may be made of cast or wrought iron.
Each platen B' is provided at its ends with two lugs c, which, when the press is
not in operation, rest upon similar lugs c¹ on the columns C to support the platens B¹
at the proper distances apart to permit the insertion and removal of the work.
When closed together upon the work by the rising of the rams D, the platens are
successively lifted off their supports, beginning at the lowest, and drop back onto
their supports in the inverse order on releasing the pressure. Steam is supplied
through a pipe to a distributing chamber F, and is thence conveyed to the platens
B and B through separate distributing pipes f, whose upper ends are connected to
the ends of the respective platens, the lower ends of the said pipes passing through
glands or stuffing boxes on the top of chamber F to permit of their moving up and
down with the platens, the lower ends of pipes f being of smooth brass to ensure
ease in working combined with tight stean joints.
A constant circulation of steain and regular degree of heat are maintained by
providing a similar chamber and pipes F', f, at the opposite ends of the platens, as
shown in Figures 1 and 3, the steam or condensation communicating through a
suitable steam trap (not shown) to the air, or returning to the steam generator by
similar means. The broad (ie., the top and bottom) surfaces of the platens BL
and the top of the follower B are planed perfectly smooth and flat or curved
(if it is desired to curve the boards and veneers), and they have at frequent
intervals small grooves b cut transversely across their faces from edge to edge, as
shown in Figure 4. The direction and number of these grooves may be regulated
according to the work to be done, but I prefer that they should be transverse, and
about three eighths of an inch apart. On the planed and grooved surfaces of the
platens are screwed or otherwise fastened thin face plates G, preferably not more
than about one eighth of an inch in thickness (shewn separately in part front and
part back view in Figure 5) of brass or other metal of good conducting quality,
having at frequent intervals rows of minute perforations g extending through their
thickness, and leading into grooves g' cut transversely from edge to edge in the
surfaces of the face plates that lie next to the platens, as shewn in the lower half of
Figure 5, which grooves g¹ correspond with the grooves b in the surfaces of the
platens, and form, by coming opposite thereto, tubular channels for the escape of the
vaporised moisture from the boards or veneers under pressure between the heated
perforated face plates.

page_text: In carrying out the combined air and press drying process of this Invention, the
boards or veneers immediately on being sawn from the log or block are separated
and left exposed to the action of the atmosphere, which, if but moderately dry,
partially absorbs the moisture or albumen from the fibres, allowing them to contract
slowly and naturally without impairing their strength. In climates where the
atmosphere is surcharged with moisture the material may be submitted to a higher
temperature than that of the atmosphere by placing the wood to be treated in a
room heated by steam or warm air blast, and provided with suitable ventilators for
the escape of the moisture in suspension. When the wood has been steamed to
facilitate cutting it into boards or veneers by means of a machine in which a
knife is employed, the immediate separation of the boards or veneers allows the
heat absorbed in the steaming process to rapidly vaporise a large portion of the
moisture absorbed from the steam, and, as in the preceding case, permits the
fibres to gradually contract and thus prepare the material for the operation of press-
drying.
The time required for air drying is determined by the thickness and nature of
the material. When the boards have thus been partly air-dried, they are brought
to the heated presses, where they are inserted between the platens, one layer of boards
only between each two platens being treated at a time. When thin veneers are
to be dried, two or three layers may be inserted at one time between the platens.
Care should be taken to cover the whole surface of the platens as nearly as possible
with the boards or veneers, to ensure uniform pressure. For rough material the
grooved platens may be used without the face plates G, but for comparatively
smooth surfaces, where finish is required, it is preferred to use the perforated face
linings. When the material has been dried under pressure, and just before taking
it out of the press, additional pressure may be given to remove any slight irregu-
larities in thickness, and to give a more highly finished surface. When this is done
the water is released from the rams D by a suitable two way or double valve t, t¹,
and the platens B¹ drop until they rest upon the lugs c as before. The dried and
pressed material removed from the press is allowed to cool in the open air before
being laid together.
If it be desired to bend the boards and veneers to curved or irregular shapes,
the surfaces of the platens B', instead of being plane, are curved or shaped
accordingly.
I interpose between the press rams and the hydraulic pump or pumps by which
they are operated an accumulator, in which power is stored by pumping in water
against air previously compressed to the amount of 300 lbs. or more to the squaro
inch, the object being to equalize and accelerate the action of the rams by the
direct action of the water under the compressed air. This accumulator may either
form part of the press frame itself, as represented in Figures 1, 2, 3, or may be
I will proceed
constructed separately, as illustrated in Figures 6, 7, and 8.
to describe its construction and mode of working with reference to the latter
Figures.
Figure 6 is an elevation of the accumulator and pumps; Figure 7 is a plan view
of the same, showing the arrangement of pipes; Figure 8 is a front elevation of the
pumps. The pump is a double cylinder pump, whose cylinders h are connected by
pipes i,, with a water tank placed on a level or a little above the bottom of
cylinders. They also communicate by pipes l, l, with blow offs m, which are
controlled by weighted safety valve S. Being put in motion, the water is drawn in
by pipes, , and forced out through pipes h, k, which have a check valve at K to
prevent the return of water by back pressure. The accumulator is composed of two
or more vertical cylindrical chambers of lap-welded hydraulic pipe iron N, N,
connected at the top by a small pipe p, closed by two valves O and P, and at the
bottom by a 5 branch coupling R with valves, having conical seats and corre-
sponding stems, operated by their respective hand wheels. n, n', n², n³, n*, are pet
cocks at different heights on the accumulator. In order to use this accumulator it
inust be charged with compressed air, that is to say, a large amount of air must be

page_text: stored into it under a small volume. For this purpose all the air of one of the
cylinders N is forced through pipe p into the other cylinder N¹ by filling it with
water; the water is then run off, and it is replaced by air, which is forced into the
other cylinder in the same way. Valves r, 2, and 3 and P are plain valves;
valve O is a spring valve that shuts down when the pressure behind ceases.
To the coupling R is connected a small pipe q, with pressure guage Q, giving the
pressure per square inch in the pipes. s is another small pipe from R to safety
valve S. x is a relief or return water pipe to tank. Two or more similar
accumulators can be connected according to the number of presses operated. To
charge the accumulator close valve r¹, close petcocks n, n¹, n², n³, n, and close
outlet t and inlet t' to the rams (Figure 3) at press. Open valve, open plain
valve P, and open spring valve 0 2 or 3 turns. Open valver, start the pumps with
safety valve S open; after 2 or 3 strokes close the safety valve by letting.
down the weight. When the hand on the pressure guage Q begins to agitate'
suddenly (indicating that all the air has passed from N to N', and that water is
beginning to pass valve O, whose section is smaller than that of inlet pipe k) open
the safety valve S by raising the weight, and stop the pump. Close valve 7 and
spring valve O. Open outlet t at press and petcocks n, n', and n*. As fast as the
water runs out of N it is replaced by air through n', and when water is all run out,
which is known by its stopping at petcock n, close n, n', and n³, open valve r, start
the pumps, and after a few strokes close the safety valve S, open the spring valve O
as before, and repeat the various operations above described. If any water shows at
petcock n³ it must be let out, being careful not to lose the air. When the guage
indicates about 1200 or 1400 lbs. per square inch pressure, valve rand outlet t being
closed, open valve r'.
Water then rushes from N to N¹ by R, and air from N¹ to N by p until the
pressure is equally divided between the two and each is half full of water, and the
pressure obtained in one column being divided by two indicates just half that
amount on the guage. Then close O and P, start the pump, open valve ?, and after
a few strokes close S and open t¹, then the water is sent to both cylinders N, N¹,
When the desired pressure is obtained valves r¹ and 2 are closed and the
accumulator is charged, the weight at S being set so as to rise at this pressure.
at once.
DIRECTIONS TO RUN THE PRESS BY THE ACCUMULATOR.
To close the press open the valve r, close the outlet t, Figure 3, and start the
pump. After a few strokes open the valves 21 and 22 simultaneously; keep these
two latter valves open during the working hours, and only controlling the action of
the water on the rams at the valve t and t¹; open the valve t' and the press will
be immediately closed, when the valve t' is shut and the pressure from the accumu-
lator ceases; during the operation of closing the press the hand on the pressure
gauge will go down a few points and indicating one or two hundred pounds less
than the initial pressure, according to the volume of water withdrawn to the ram
cylinders and the pipes conducting thereto; but as the pump continues to run it
will soon get up the pressure in the accumulator again to the point regulated by
the weighted safety valve S, which will then open of itself and relieve the pumps,
which will then merely draw water from and force it to the supply tank through
the small relief valves m, m, which connect with the tank at the top by two flexible
rubber or fixed metal pipes; in doing this the high pressure from the accumulator
acting through the small pipes on the underside of the weighted lever S causes
the latter to rise when the short end of the lever acts upon the pistons in the
small valves m, m, and opening the outlets to the waste pipe connecting with the
tank. When the inlet at the press is opened and water is drawn from the
accumulator the decrease of pressure in the latter causes the weighted lever S to
drop, when the pistons in the small valves m, m, are forced outward by spiral
springs under their heads and the communications to the tank are cut off; the
water by the action of the pump is forced through pipes k¹ to the accumulator

page_text: again and the former pressure restored, the accumulator will suffice to close the
press a few times without the pump if necessary. When guage on the accumulator
indicates the highest pressure which the safety valve allows, and just before the
wood being treated is ready to be taken out, the outlet t being closed, the inlet t¹
to the rams is opened and the second and higher pressure is imparted to the wood,
which, being at this time dry, receives a polish on its broad surfaces without being
sensibly reduced in thickness. After the wood has received this higher pressure for
an instant the inlet valve t' is shut off and the outlet valve t'is opened, when the
water sustaining the rams is released through suitable pipes to the tank again; the
platens then separate and assume their original and open position; this pressure
of water on the rams, being cushioned by the elasticity of the air in the accumu-
lator, can be applied at all times without danger to the presses or injury to the
wood. In Figures 1, 2, and 3, the columns C of the press are hollow and serve
also the purpose of the stand pipes of the accumulator, they being connected
together and with the pumps and ram cylinders by pipes provided with check
valves, arranged to operate precisely as described in reference to Figures 6 & 7,
so that no further description is necessary.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is,-
1st. The combined process of air and press drying boards and veneers, sub-
stantially as herein described.
2nd. In the process of drying boards and veneers under pressure between heated
plates, the application of a final or terminal finishing pressure superior to the initial
or drying pressure for imparting a smooth surface, substantially as specified.
3rd. In a press for drying boards and veneers under pressure; the heated pressing
plates having grooves or channels on their faces for the escape of vapour from the
wood being treated, substantially as shown and described.
4th. In a press for drying boards and veneers under pressure, the combination
with the grooved press plates of face plates correspondingly grooved and perforated,
substantially as and for the purpose specified.
5th. In a press for drying boards and veneers under pressure, the employment of
a series of pressing plates supported when not in operation at the proper distancos
apart to receive the work between them, and adapted to be successively closed
together upon the work by the rising of the hydraulic rams, substantially as shown
and described.
6th. In a press for drying boards and veneers under pressure, the combination of
a series of hollow pressing plates adapted to be closed together and separated from
one another, as herein specified, and series of pipes connected to the respective
platens and sliding through stuffing boxes in steam distributing and collecting
chambers, substantially as and for the purpose set forth.
7th. A compressed air accumulator constructed of a pair of stand pipes connected
together by tubes with check valves, combined to operate substantially as herein
specified.
8th. The employment, in combination with a press for drying boards and
veneers under pressure, of a compressed air accumulator interposed between the
press rams and the pumps, and constructed to operate substantially as herein
specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
1001