Improvements in or relating to Sieves, applicable for Purifying, Grading, or Separating Grain and other Substances.
Year: 1890

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c., Act, 1883), as allowed
by the decision of the Comptroller General of the 27th day of March 1897.
Date of Application, 17th Mar., 1890
Complete Specification Left, 6th Nov., 1890-Accepted, 6th Dec., 1890
Improvements in or relating to Sieves, applicable for Purifying,
Grading, or Separating Grain and other Substances.
We, TOM PARKINSON, and GEORGE MARSDEN PARKINSON, of Doncaster Mills,
Doucaster, in the County of York, Millers, do hereby declare the nature of this
invention to be as follows:-
This invention relates to improvements in the construction and working of
oscillating or otherwise moving sieves used for purifying, grading, or separating
middlings, grain or other substances and may be briefly described as follows:-
Instead of using the whole surface of the tray or sieve for the purpose of
purification or sifting of the material under treatment one or more narrow longitudinal
channels suffice for our purpose. These run in parallel lines the length of the tray, a
suitable distanco apart, and inay be slightly tapered in width towards the delivery or
tail end so that the quantity of material sifted through at the head end may not
diminish the thickness of the stream and thus offer an unequal resistance to the
pressure of wind which may be blown or exhausted through it. The remainder of
the tray surface we prefer to make up of solid or wind proof sections intervening
between the aforesaid sieve channels. These dead spaces form expansion room for
the air causing it to deposit the solid matter it may in its passage through the sieve
have lifted from the material under treatment and to escape free from such solid
matter to the outlet. Over each sieve channel and running the entire length of it is
a cowl or hood or deflecting board which expedites the deposit of the material on to
the dead parts before referred to. The wind coming with its full force up the narrow
channel immediately strikes this board and is at once deflected to either or both sides
and the solid particles being thus thrown out of the influence of the air current
settle and are removed by the motion of the tray carrying them to the tail end or by
other suitable means if the deposit or dead portions of the tray do not partake of
the shaking motion of the sieve portion or portions. The top side of the deflecting
boards may form a channel for the depositing and carrying off of any particles of
light dust or flour which may by reason of their small specific gravity have floated
above the underside of thein. The sieves must oscillate or rotate or shake in sɔme
manner to ensure the travel and separation of the material but the dead parts may
either be part and parcel of the sieve portions shaking with them or can be
independent having special devices for clearing off the deposited material.
Such special devices could be worm or other form of conveyors working in the
dead stationary sections and carrying off the material as deposited or the dead

page_text: sections could be made to slope outwards from a centre sieve channel so that the
deposited material would fall away of its own weight and be let out of the machine
by suitable valves.
Improvements in, or relating to Sieves, applicable for Purifying,
Grading, or Separating Grain and other Substances.
We, TOM PARKINSON, and GEORGE MARSDEN PARKINSON, both of Doncaster
Mills, Doncaster, in the County of York, Millers, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement ;-
This invention relates to oscillating sieves used for purifying, grading or separating
middlings, grain or other substances and may be described as follows ;-
Instead of using the whole surface of the tray or sieve for the purpose of
purification or sifting the material under treatment a narrow longitudinal channel
suffices for our purpose. This runs the length of the tray and is preferably tapered in
width towards the delivery or tail end so that the quantity of material sifted through
at the head end and onwards may not diminish the thickness of the stream and thus
offer an unequal resistance to the pressure of wind which may be blown or exhausted
through it. The remainder of the tray surface is made up of solid or wind-proof
sections which serve as deposit surfaces for the dust and which when the sieve
portion is taper expand in width towards the delivery or tail end simultaneously with
the diminishing width of the sifting portion. By this means if extra wind is
required and provided at and towards the tail end to operate on the heavy material
still left on the surface of the sieve it finds gradually increasing expansion room and
deposit surface. These dead sections provide expansion room for the air causing or
allowing it to deposit the solid matter it may in its passage through the sieve have
lifted from the material under treatment and to escape free from such solid matter at
the outlet.
In the accompanying drawings ;—Figs. 1 and 2 are respectively a transverse
vertical section and a horizontal section of apparatus constructed according to this
invention the latter view representing the sieve and deposit surfaces in plan and the
hood or cowl removed.
Like letters indicate like parts in both figures.
A is the case in which the apparatus is enclosed. B is the sieve or silk and B' the
wind-proof sections or deposit surfaces which together as one piece are preferably
carried by vertical springs or rods (not shown in the drawings) so as to permit of the
requisite vibratory movement being imparted by means of an eccentric on the shaft C
or by other suitable means. The size and shape of B can be varied but Fig. 2 gives
a fair idea of the preferred proportions a sieve 9 feet long and tapering in width
from 18 inches at the head end down to 5 inches at the tail end as illustrated giving
excellent results in practice. The sieve and deposit surfaces (hereinafter for
convenience when referred to as a whole indicated by the letter B B') preferably
incline towards the tail end, 1 in 48 being a suitable gradient, but they may incline
more or less than this. At the outer longitudinal edges of B are provided joint
strips A' and at the lateral edges at the head and tail end of the machine B B¹ is
connected to the case A by strips of cloth or equivalent material all of which is for
allowing B B' to be vibrated whilst preventing the leakage of air past its edges.

page_text: D is the outlet through which falls the material passed over the sievo B and from
which material the dust or other impurities have been removed by the air currents
passing upward through the sieve and E, Fig. 2, is a screw conveyor for conducting
the dust and impurities from the tail end of B¹ to the outside of the machine.
F, Fig. 1, are screw conveyors for conducting to the outside of the machine the
purified material which falls through the sieve B. G, Fig. 1, is the hood which runs
centrally from end to end over the sieve B to direct the lifted impurities on to B¹ and
which is preferably connected by suitable supports to B'. G' are cheeks secured to
B B' one on each side of sieve B to guide the material as it passes along the sifting
surface.
In the operation of the before described apparatus the material to be treated is
charged into the machine through the hopper H, Fig. 2, which delivers it on to the
head or wider end of the vibrating sieve B. In passing over B a portion of the
heavier purified material according to the size of the particles falls through the sieve
and is conducted to the outside of the machine by the conveyors F, Fig. 1, and the
lighter impurities are drawn or blown up from the sieve as indicated by the arrows in
Fig. 1, by the wind or air currents which may be created by an exhaust fan at the
upper side or blowing fan connected with the underside of the sieve or by any other
suitable means.
The dust-laden wind which has passed through the sieve B enters
the spaces I where it expands and the dust previously suspended in it falls on to the
deposit surfaces B' and also onto the deposit surface G³ formed on the top of the
hood G from all of which surfaces B₁ and G³ the dust falls into the trough of
the conveyor E by which it is conducted away.
When the space 1 is of sufficient capacity in relation to the superficial area of the
sieve B experience has proved that practically no particles of dust are carried away
into the surrounding atmosphere with the escaping wind and so far as those
proportions are duly observed it is immaterial whether the sieve and deposit surfaces
are taper or parallel but the former construction is preferred because it compensates
for the quantity of material sifted through at the head end and onwards and preserves
a uniformity in the thickness of the stream of material and in the resistance
presented to the wind blown or exhausted through it and moreover by this tapered
construction when extra wind is required and provided at and towards the tail end to
operate on the heavy material still left on the sieve D it finds gradually increasing
expansion room in I and surface B' for depositing the impurities it carries with it.
Even if the sieve B is not tapered but throughout its length kept the same width
as at the head end it will be seen that compared with ordinary sieves it is narrow in
proportion to its length and to the size of the case A in which it is enclosed.
The deposit surfaces may either be formed in part and vibrate with the sieve as
before described or they may be stationary.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, wo declare that what we
claim is :-
In apparatus such as described the combination with a central sieve and one or
more side deposit surfaces of a deflector G substantially as described and illustrated
in Figure 1 of the accompanying drawings.