IMPROVEMENTS IN MACHINERY FOR BENDING OR SHAPING TIMBER
Year: 1856

page_text: PROVISIONAL SPECIFICATION left by Richard Archibald Brooman at
the Office of the Commissioners of Patents, with his Petition, on the
2nd May 1856.-A communication.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN MACHINERY FOR BENDING OR SHAPING TIMBER," (com-
municated to me by a foreigner residing abroad,) to be as follows:-
This Invention consists of improvements in machinery for bending or shaping
timber, especially adapted for the formation of curved timber for ship-building.
In the construction of timber bending machines, heretofore, the clamping
trough which holds the beam is moved from one end only, the opposite half or
end remaining stationary, which increases the resistance and power required to
work the machine; and one of the improvements in the present Invention
consists in such an arrangement that both ends of the trough are moved
simultaneously, whereby the power required to operate may not only be
reduced, but the work' is also superior.
A second improvement is in a means for preventing the breaking of the
fibres on the outside of the wood at the angle or bend. This is accom-
plished by dividing the draw chain and fixing it at the middle to a strong
moveable block, which may be set up by a strong screw, so as to press
upon the wood at the weak point, and thus support the fibres.
nection with this; means are also provided to keep up the pressure at this
In con-

page_text: point after the timber is removed from the bending trough, and until it
The
has become fully set and dry, and this part is called the mould.
machine is constructed as follows:-The bending trough is in two parts,
joined at the centre to an axis. The bottom of each part consists of a wide
strong plate A. From the inner ends of each part an arm B extends, at an
acute angle outward. These arms, where they join the plate, are widened out
so as to overlap, and upon the bed beneath a strong plate C, Figure I., is
fastened, which passes through these two plates, and is the centre on which the
bending trough turns, the arrangement forming a rule joint of the form repre-
sented in the Drawing.
c, Figure I., is a sunken space, cut away from the face of the upper
arm B to receive the bottom plate of the mould piece which lies under the
wood to be bent, and when thus under, forms part of the bottom of the
trough; the upper surface must, therefore, be upon a general level with the
plates A. The pieces which form the inner side D of the trough are hinged
to the plates A at each outer end, as seen at d, so that their inner ends
may be raised when required. The two outer pieces E, forming the other
side of the trough, simply lie upon the plates, as these pieces must be free to
slide along during the bending operation. The cross blocks forming the ends
of the trough are fastened to these latter pieces, as shewn at E'. One end e
of each of the chains is fastened to the outer pieces E, the inner surface of E
being cut away sufficiently to allow the chain to lie in flush with the surface.
The other ends of the chains are secured to the clamping block, placed half
way or opposite to the turning axis of the trough at i; this block plays in a
guide frame G, at the back of which is a screw., to set the same forward and
press it against the timber while bending. The sides E do not quite meet.so
as to allow the block to come up against the plank. The end which presses is
not a plane surface, but is hollowed out, as shewn at 1, to allow of the wedge
being driven which is connected with the mould, and still maintain the
As the pieces of
pressure upon the angle of the wood after it is taken out.
timber vary in size, the sides of the trough must be arranged so as to accom-
modate them. This is effected by the movement of the pieces E, as..they
merely lie upon the bottom plate. At the back of this slide E is a series of
set screws g, playing in nuts cast upon the bottom plates A; and between the
points of these, at the side plates, is a set of friction rollers h, arranged to
vibrate upon their stocks or arms, so as to be kept in place. The timber to be
bent is strapped. on that side which lies against the chain e by an iron plate,
which bends with it, and must be kept upon the timber after its removal from
the trough, as shown at o, Figures I. and. II. Each end of the plate is bent

page_text: to a right angle, and must cross the end of the timber, which accordingly must
be cut square on the end, and to a length to fit within. When the timber is
placed in the trough a cover must be put upon it in order to confine the wood
upon all sides. To accomplish this, three plates are laid on and clamped down,
two of the plates being straight, as seen at p, while the third is a curved piece,
of the shape shewn at q. To keep these plates down there is a row of brackets /,
under which wedges are driven. The mould is a detached piece, and is of
the form represented in Figure III. The part r forms a portion of the bottom
of the trough (when lying in the sunken space c, Figure I.), its surface being
flush with the general surface of B. The part forming the mould is at s', and
is.a strong curved plate. The arc is struck from C, Figure 1, as a centre, and
the timber forms upon this in the act of. bending, as seen at Figure II. The
central post s''is for the purpose of taking on the braces r, through which the
wedge or key t passes and locks into the lower plate.. " are two other posts
which receive the keys by which the curved cover q is kept down upon the timber.
The operation is as follows:-Unwinding the chains from the capstan K, the
arms B are opened out until the trough is brought into a straight line. The
pieces p, q, forming the cover, are out of the way, the two sides D thrown up,
and the bed plate A all clear, for the reception of the piece of timber to be
bent, the ends of which are to be first squared, the iron band o fitted on, and
both put in, pushing the timber (which has been previously steamed) over until
the band presses against the chain e. If the timber is to be bent exactly in
the middle, the centre must be placed exactly opposite to the clamp i, the
timber being represented in place at X, Figure I. A block P is then placed
in each end, which is pressed hard up against the end of the timber by the
screws P. The set screw is turned to force the clamp i up, as are also the
several screws g; finally, the braces w are put upon the heads of the brace
studs, and all is in readiness. The bending is now performed by turning the
capstan K, whereby the arms B are drawn together. As the trough lies at
one side of the axis C, the moment the bending commences, the two ends,
abutting at the middle, begin to part asunder, whereby the block P would be
carried away from the ends of the timber; but to prevent this, and enable the
pressure to be still maintained, is the reason for leaving the side pieces E free
from the bottom plate A, and connecting these pieces together by the chain e,
attached to the clamp i in the centre block; thus the plate A will slide along,
carrying the side D with it. This produces a peculiar action at the point of
bending of the timber, since it compels the fibres to contract or be compressed
together, beginning at the outer side and gradually increasing in degree to the
inner one.
This compression is produced by the blocks P at the end in con-

page_text: nection with the pressure block i, for, were these blocks Pout of the way, the
tendency would be to part the outer fibres. The pressure block i serves to
support and keep the fibres together until the wood has become fairly set and
dry, when the danger no longer exists.
As the drying occupies some days, it is important to be able to relieve the
machine by taking out the timber, in order that the machine may be constantly
employed in performing the bending operation, as otherwise the number of
machines would have to be multiplied to a great extent. The mould, there-
fore, is detachable, and is lifted out with the bent timber; but previous to this,
in order to keep up the pressure on the fibres when the block i is to be with-
drawn, the key or wedge t is driven in. The braces are then taken off, and
the sides D thrown open. The two ends of the metal band o, having been
first connected by a rod o', Figure II., the bent timber may be removed, as in
Figure II., and will be retained in that position until dry, when it will have
become firmly set; the mould, band, and rod, may be then permanently re-
moved.