Improvements in or appertaining to Rotary Flat Sieves and Sieve Bottoms or Sieving Devices.
Year: 1896

page_text: Date of Application, 29th Apr., 1890
Complete Specification Left, 1st Mar., 1897-Accepted. 3rd Apr., 1897
pplication, 29th Apr., 1890
Complete Specification Left, 1st Mar., 1897-Accepted, 3rd Apr., 1897
PROVISIONAL SPECIFICATION.
Improvements in or appertaining to Rotary Flat Sieves and Sieve
Bottoms or Sieving Devices.
I JAMES HIGGINBOTTOM. of 32, Seel Street, Liverpool, in the County of
Lancaster, Milling Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention has for its object a method of and appliances for enabling
the material on a rotary flat sieve to move forward from the feeding to the
delivery end.
The improvement consists essentially in forming a surface, the longitudinal
section of which shall consist of a series of inclined planes with vertical terminations
forming corrugations somewhat similar in appearance to a ratchet rack, the vertical
faces facing in the direction in which it is desired that the material shall travel.
There are various ways in which these corrugations can be arranged, thus the sieve
can be formed of a sieving surface sloping upwards to a given point and then a
sudden descent followed by another slope and so on, the silk or other material
being in such instance passed between bars or frames of wood or the like so as to
form a framework for the corrugations; or the sieve or bottom can be flat and
a series of corrugations placed above it preferably approaching slightly nearer the
siere near the tail end than at the head. The length of the corrugations varies
with the stroke and I have not yet worked out the exact best length of corrugations
for the different varieties of material and throw of the crank. My preliminary
experiments indicate however that from one to one and a half times the double
throw of the crank or diameter of rotation is about the proper length for corruga-
tions. It will be obvious that what is applicable for sieves is also equally
applicable for sieve bottoms and that these latter can be corrugated or can have
corrugations above them. Theoretically a corrugated sieve or sieve bottom is
better and feeds more evenly than a plain one having corrugations above, but there
are two advantages in the latter plan, first, that the sieve can be perfectly smooth
and therefore more adaptable for brushing, secondly, that the corrugations being
placed above have a tendency to level the height of the material on the sieve, as
if there be little material on the sieve there is little or no propulsion, whereas if
there be a thick layer the propulsion is more rapid as the vertical sides of the
corrugations are able the better to act on the material.
Instead of the vertical faces to the corrugations I may sometimes make such
faces at an angle to the vertical.
The sieves or trays may be so placed that a line drawn through the highest
or lowest points of the corrugations or inclined surfaces may be either horizontal
or inclined.
220
1000
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Patent Agents for the Applicant.

page_text: Improvements in or appertaining to Rotary Flat Sieves and Sieve
Bottoms or Sieving Devices.
I, JAMES HIGGINBOTTOM, of 32, Seel Street, Liverpool, in the County of
Lancaster, Milling Engineer, do hereby declare the nature of this invention aud
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention has for its object a method of and appliances for enabling the
material of a rotary flat sieve to move forward from the feed end to the delivery
end. The improvement consists essentially in forming a surface, the longitudinal
section of which consists of a series of inclined planes with vertical or nearly
vertical terminations forming corrugations somewhat similar in appearance to a
ratchet rack, the vertical or nearly vertical faces facing in the direction in which
it is desired that the material shall travel. The sieve surface itself can thus be
formed into corrugations, or the sieve surface, or the sieve bottom as the case may
be, may be flat, and have a corrugated cover above it, this cover or its corrugations
preferably approaching slightly nearer the sieve near the tail end than at the head.
The length of the corrugations varies first with the stroke, secondly with the speed,
and thirdly with the material and it is impossible to give exact directions for all
kinds of material. A good plan however, is to be able to slightly regulate the
stroke. For middlings dressing a length of stroke of four inches, a length of
corrugations of six inches and a speed of 180 revolutions a minute are found
satisfactory. If, however, the crank be made adjustable it can be adjusted for
each variety of material. Theoretically a corrugated sieve or sieve bottom is
better and feeds more evenly than a plain one having corrugations above, but
there are two advantages in the latter plan, first, that the sieve can be perfectly
sinooth and therefore more applicable for brushing, second, that the corrugations
being placed above have a tendency to level the height of the material on the
sieve as if there be little material on the sieve there is little or no propulsion,
whereas if there be a thick layer the propulsion is more rapid as the vertical sides
of the corrugations are able the better to act on the material, consequently, the
thin parts remain nearly stationary, while the thick parts are very rapidly levelled
down, thus causing the whole to assume an approximately even thickness of material
on the sieve. The sieves or trays may be so placed that a line drawn through the
highest or lowest point of the corrugations may be either horizontal or inclined.
For ordinary middlings purifying, however, I prefer a horizontal section. In order
to further illustrate my invention I append the accompanying drawings showing
a transverse section of a plan-sifter. In these A is the box, B suspension straps
or rods, ordinary rotating device. D driving band, E entrance for feed,
and F1, F2, F, and F exits of material. G', G, G, G corrugated sieves,
H', H2, H3, H corrugated trays. H corrugations sometimes applied to the upper
surface of the box. These however are not necessary when the sieves are
corrugated. The feed from E passes along sieve G and the tailings pass over
at F. The throughs pass on to tray H and from there on to the sieve G
when again the tailings pass through at the end and the througlis pass on
over the tray H2 on to sieve G. This is continued until the finer thronghs pass
out at F.
In thus describing my invention, I wish to confine it to sieves in which the
material enters at one end and passes out at the other, and in which every part of
the sieve has the same amount of motion, the main value of the invention being
that by these means perfectly level sieves and sieve frames can be used and a large

page_text: number of sieves and sieve bottoms can be superimposed in a small space. Further,
it is obvious that the corrugated bottom of the sieve can actually be used to propal
the material along a smooth tray beneath in the opposite direction and thus a very
great saving in space can be obtained. The principle of my invention might,.
suitably varied, be applicable in the case of single sieves, conveyors, or the like,
but as the main advantage of this invention consists in being able to have a large
number of sieves and trays superimposed in a small space having the rotary or
hand sieve movement on the level without the use of jerking propelling mechanism
which would dash the material about, I have decided to make no claim for these.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
The improvement in or appertaining to rotary flat sieves and sieve bottoms in
which numerous sieves or sieve and trays are superimposed, which consists in
forming the sieves or trays in ratchet steps or with ratchet stepped covers which.
can be formed of the sieve or tray above, said ratchets being formed in lines crossing
the sieve, substantially at right angles to the direction of travel of the material
substantially as and for the purposes described, whereby the material can be propelled
on the level or even on the upward slope without the use of other mechanism than..
the moving sieve or tray surface itself.
Dated thin w7th day of th
1007
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.