IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF GROUND WOOD' PULP
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by John Evans-Freke Aylmer at
the Office of the Commissioners of Patents, with his Petition, on
the 18th September 1873.
I, JOHN EVANS-FREKE AYLMER, of No. 27, Walbrook, in the City of
London, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF GROUND WOOD' PULP,"
to be as follows:-
In the manufacture of wood pulp by the mechanical process as
heretofore carried out blocks of wood are presented lengthwise of the
grain to the surfaces of grindstones, which in abrading small particles or
fibres of wood from the block to form pulp of necessity converts a great
portion thereof to an impalpable powder which has little or no value for
the manufacture of paper.
Now my Invention has for its object to facilitate the grinding, to
prevent as much as possible such formation of wood powder, and to
ensure that all or nearly all particles of wood separated from the blocks
shall consist of fibres of a certain length. For this purpose I apply to
the grinding surface of the grindstone, whether of steel, iron, or stone,

page_text: one or more rows of knives or steel cutters projecting somewhat beyond
such surface, and so arranged that as the grindstone rotates such cutters
make incisions at small distances apart upon the surface of the wood
blocks in contact with the grindstone. By this means the fibre of the
wood is cut into short lengths, and the separation of such short lengths
of fibre from the block is consequently effected by the grindstone with
such comparative facility as to prevent the reduction of the fibres to
powder. The said cutters may be variously constructed and arranged
for the above purpose.
In the arrangement which I prefer to employ a number of small
discs with sharp edges are placed at small distances apart upon a pin
carried in a box which encloses the discs all but small portions of the
circumference thereof which protrude through slits in the box. The pin
has small projections fitting into corresponding notches in the discs, so
that these are prevented from turning on the pin, while the pin together
with the discs can be turned from time to time in the box so as to bring
a fresh portion of the disc into action when the other part has become
blunt. The discs are held in place at the required distance apart by
partitions in the box which also serve as supports to the pin. The said
box with cutting discs is inserted into a corresponding groove formed
in the grindstone so that the said portions of the cutting discs protruding
through the box project beyond the grinding surface, and the box is
secured in this position in the grindstone by any suitable means, such as
by threaded bolts fixed at the ends of the box passing through lugs on
the sides of the grindstone, and secured thereto by screw nuts.
If two or more such rows of cutters are employed they may either be
so arranged that the cutters of the one row make incisions in the wood
at the same points as the other row, or so that the one row of cutters
make incisions in the wood between the incisions made by the other
row.