Improvements in or relating to Sieves, and in Apparatus therefor.
Year: 1894

page_text: Date of Application, 20th Oct., 1894-Accepted, 29th Dec., 1894
COMPLETE SPECIFICATION.
Improvements in or relating to Sieves, and in Apparatus therefor.
A communication from FRIEDERICH BRANDSTAEDTER, Engineer, of
Louvain, Belgium.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent, 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 :-
A flat sieve reciprocating to and fro in the usual well known manner, can in spite
of its horizontal position, deliver the material to be sifted from one end of the
sieve to the other, when placed as shown in Figures 8-10 of the accompanying
drawings.
The sieve is formed with a number of obstacles which regarded in plan are
wedge-shaped. The material to be sifted when the sieve is in operation is pierced
and separated by the wedge-points, on the side to which the latter are directed
and thus move towards the right, by reason of the motion of the sieve to the
left. When the sieve however moves to the right the broad ends of the wedge-
shaped obstacles avail to carry the matter to be sifted in the same direction, so
that only a small portion thereof retrogrades on the sieve to the left. This
causes the material to move steadily across the sieve from left to right.
The same principle equally applies when the obstacles are wedge-shaped in
vertical section instead of in horizontal section, as shown in Figures 11-13. In
this case, they must not touch the bottom, i.e. the actual sifting surface, but be
arranged slightly above it. When the sieve is moved to the left, a certain
quantity of the material to be sifted must owing to the wedge-shaped space
between the obstacles and the sieve-bottom, be delivered to the right, in relation
to the sieve; but then on the return movement of the sieve to the right,
encountering the broad ends of the hindrances, the bulk of the material being
gifted carried along with the sieve, so that the result is that the bulk of it is
delivered to the right as in the first case above described.
It is obvious both these kinds of obstacles may be utilised together, as e.g. the
one above the other; and also that the form of the obstacles or hindrance is not
limited to that of a triangle (or wedge) but may only approximate thereto. Thus
by the conjoint application of the two wedge forms specified, pyramidal shapes
would be obtained which would give the same working results.
In Figure 14 is illustrated another modification of the principle above set forth.
In this case, the sieve is divided longitudinally for the greater part of its length,
into two compartments in one of which the obstacles are so arranged that a forward
delivery of the material under treatment is obtained, say to the right whereas in
the other compartment the arrangement is reversed, so as to give a backward
delivery, i.e. to the left.
The transfer of the material from the first to the second half or compartment of
the sieve can be advantageously and suitably facilitated by the insertion of a
alanting. corner or guide-piece as shown. At the left end or termination of the
second compartment an opening is provided in the sieve bottom, through which the
material under treatment falls into another sieve or receptacle placed suitably
beneath it.

page_text: This arrangement shows how to cause the transmission of the material under
treatment from one end to the other of the sieve (say, from left to right) and vice
versa; and it offers the advantage, on the one hand, of keeping the material during
a longer period of time in contact with the sifting surface, and on the other hand
of being enabled to feed several sieves from one and the saine end.
Further, Figures 15 and 16 illustrate a device or arrangement whereby the silk
bottom of the flat sieve can be kept clean. This consists in the provision of
longitudinal slack strings or ribbons extending in the direction of motion of, and
attached to the ends of the siere, with small transverse strips or bands fastened
thereto, touching the silk, the strips or bands by their own weight or with the
assistance of the flour or material on the sieve remaining more or less stationary
while the sieve is reciprocated.
-
The flat sieve described in the foregoing, is utilised in practice by arranging a
suitable number of them, one above another in a box or casing, and fully charging
them, when a special apparatus may be employed to operate them.
Such an apparatus is illustrated in Figures 1-7 of the accompanying drawings.
Figure 1 shows two sieve-boxes A and B thus combined, in elevation, and
Figure 2 is a view of the same as seen from above; while
Figures 3-7 exemplify sundry details thereof.
The sieve-boxes A and B are arranged on opposite sides of a driving shaft C,
and are so actuated respectively by the eccentrics D and D', secured to the shaft
at an angle of 180° from each other, that both sieve-boxes simultaneously advance
towards and recede from the central shaft, so that the contrary moments of the
opposed working parts counterbalance each other, as the two sieve-boxes are
equally loaded.
The free ends of the sieve-boxes are carried by springs and the ends adjoining
the eccentrics on rollers. The springs E are of special construction and secured in
rigid frames, which serve also to carry the bearings of the shaft C.
Each of the eccentrics D and D' works in an iron frame G screwed on to the
sieve-box (Figures 3 and 4) in which steel bars H. rounded on the outer side
are so arranged that the distance between the inner surfaces, with which the
periphery of the eccentric comes in rolling contact, admits of regulation by means
of a sliding wedge J adjustable by a screw, whereby on the one hand, continuous
close contact of the rubbing surfaces is attained, and on the other hand shock and
vibration are diminished. Beneath the frame or cast-iron box G wherein as
described the eccentric rotates is a roller which runs in a small oil-receptacle,.
the box G sliding to and fro on this roller lubricates itself.
The special construction and arrangement of the springs E is illustrated in
Figures 5-7. They consist of two or more plate-springs E, which are fastened at
top and bottom in boxes or sockets E' E' and strengthened and kept apart by short
plate-springs e transversely set. -
This arrangement has for its object to transfer the stress from the end portions
more to the centre, and so attain to a more equal distribution of elastic effort over
the entire length of the springs. In order to facilitate the securing of the springs
to the boxes, a movable dovetailed joint-piece E' is attached within the box by a
screw-bolt and nut together with the end of the plate-spring. The upper box or
socket E is screwed to the longitudinal beam of the framework F of the apparatus
while the lower.box E' is secured to or formed in one piece with an angle-iron or
L-bracket E' screwed on the bottom of the sieve-box.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent, and in what
manner the same is to be performed, I declare that what I claim is :-
--
1. A reciprocating horizontal flat sieve having suitable preferably wedge shaped
bodies arranged above the sifting surface in such a manner as to cause the
substance under treatment continually to move in a given direction substantially
as described and illustrated in the accompanying drawings.

page_text: 2. The division of a flat sieve into two longitudinal compartments in which
suitable bodies are so arranged that the material under treatment advances in
one direction in the first compartment and in the opposite direction in the second
compartment in order that the material may remain longer in contact with the
sifting surface and also that several sieves may be fed from one and the same
end substantially as described and illustrated in the accompanying drawings.
3. The arrangement of sieve boxes such as A and B on opposite sides of a
driving shaft on which are keyed at a suitable angle relative to each other
eccentrics such as D D' working inside frames such as G secured to the sieve
boxes substantially as and for the purpose described and illustrated in the accom-
panying drawings.
4. The suspension of the free ends of sieve-boxes such as A and B by springs
or the like and the support of their inner ends by rollers for the purpose of
lubrication substantially as described and illustrated in the accompanying drawings.
5. The combination with sieve-boxes such as A and B of springs such as E for
the suspension of the free ends of these boxes such springs consisting of two or
more parallel plate-springs strengthened and kept apart at their ends by short
pieces such as e and secured at top and bottom in boxes or sockets such as E¹ E*
by means of dovetailed plates such as E³ the upper sockets E¹ being secured to the
frame while the lower sockets E' are secured to the sieve-boxes the whole
operating substantially as and for the purpose described and illustrated in the
accompanying drawings.
6. The combination with sieve-boxes such as A and B actuated by eccentrics
such as D D¹ of the arrangement in the eccentric frames G of segments or plates
such as H and of adjustable wedge plates such as J so arranged that the distance
apart of the inner faces of these segments can be regulated for the purpose of
ensuring suitable contact between the periphery of the eccentric and the said inner
faces and reducing shock and vibration in the reciprocating motion substantially as
described and illustrated in the accompanying drawings.
7. A device for keeping the surface of the sieve clean by the arrangement of a
longitudinal ribbon cord or the like fitted with small transverse strips or ribbons
substantially as described and illustrated in the accompanying drawings.
Dated this 20th day of October 1894.
W. P. THOMPSON & BOULt,
Agents for the Applicant.