Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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2.
Thls invention relates to a methocl of manufacture
of gravity fcd cylindrical separating screen.
The invention is particularly applicable to a
screen adapted to provide an alignment of seed separation
(the term seed to be understood to incorporate all
forms of seed in the widest possible concept of this
term wherever there is an applicable sizing technique
required).
The problem has been hitherto that there has been
generally no economically viable method to manufacture
apparatus to perform this separating technique.
It has been considered that by providing such
an alignment that is by providing an internal groove
within a cylinder and then having a sizing gap or a
separating gap below this or behind this that there would
be good separa-iorl e~l-ects available.
The problem however has been to provide such a
cylinder which not on]v mtlst provide this effect but
must also be able to be mal~llEaclllred economically.
Obviously or-e~ could manufacture such a device
by simply casting a unitary structure but the costs
of dies and the therefore single cost of each separating
cylinder made using this technique considering the
marlcet available, makes such a proposal not economically
and therefol-c commcrcially feasible.
One proposal envisages a metal sheet having a
plurality o~ grooves form across the sheet ancl thereafter
having a plurality of slots punched througll thc shcet
in the troughs of the grooves and thereafter thc sheet
1~
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3.
being rolled so as to be formecl with the grooves following
a circular path around the inside face of a cylinder
then formed by the metal sheet.
A difficulty with this proposal is to provide
for the grooves in the first instance.
Analysing this problem further, it has the economic
viability of providing such grooves that is the difficulty
in relation to the speciic art.
In other words provided there is unlimited funds,
one can obviously achieve a product of this type perhaps
by providing a cold roll line or otherwise, but such
techniques are only viable in terms of large volumes
in cases where the size shall be the same.
This is simply not feasible in terms of this parti-
cular art in that e~en with large separation volumes
being required, the number of devices as such need
not be extensive and in an~ event, the separation between
respective grooves has l~o L~c selectecl with some care
for each application ancl mi3y in fact need to be tailor
made for each particular case.
Use of a technique in which one groove at a time
is pressed into the metal has been considered using
a device generally referred to as a "press brake" but
because the location of onc groove must bc closely
related to a fol]owing groove, and the location of
the first groove may necessarily hold the metal from
being drawn into the subsequent groove upon pressing
of this.
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At least that has been hitherto consi.dered to
the extent that despite extensive investigation and
advice, it has not been hitherto economically or commer-
cially feasible to provide Eor manufacture oi such
devices by using a press technique incorporating a
press brake.
In the event, such convèntional advice has been
proved to be wrong. .
By discovery and by development, it has now been
discovered that it is possible to use a press brake
technique to provide Eor grooves in sheets of metal
for the purpose discussed and this can therefore be
achieved both economically for the specialised application
and to this extent it is commercially viable as an
answer to the problem.
The inven~-ioll :in one iorm can be said to reside
in the method oi m.lllufacture of a gravity head cylindrical
seed screen, the steps o:E stamping by use o:E matching
dies a first groove into a sheet of metal, the groove
having a front sidc pr~rtioll a t'i~r side, and a base
portion and then locating the thus formed groove a
selected distance ~rorn a Lemale portion of the die
for the stamping of a further groove parallel to the
first groove, holding the sheet thus while stamping
the next groove, then repeating said last step using
the previously formed groove, cutting slots along the
bnse of the grooves allcl sh;3p:ing thc thus worl<ed shcet
into a cylinc3rical shape where the groovcs arc? each
following a circular shape which is coaxial with the
circular shape followed by adjacent grooves.
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5.
PreLe~a~ly the sheet of metal is held in an inter-
locking relationship by the female die for a first
groove when located for the stamping of a subsequent
groove in the adjacent parallel alignment.
Preferably this interlocking relationship is effected
by a rearward facing face of the female die being position-
ed against a forward facing side of the front side
of the first said groove.
The invention will be better understood with reference
to a preferred embodiment which shall now be described
with the assistance of drawings in which :-
Figure 1 is a side elevation of the male and femaledies with a metal sheet about to be stamped for a succes-
sive groove and
Figure 2 is the sallle view as in Figure 1 with
howe~ver the male (I;e having stamped the groove.
Referring in detail to the drawings, it will be
seen that there is a em<ll( an-vil die 1 which includes
a first platform portioTl ~ al-d then a rectangular depres-
sion 3 having a front face 4, a rear face S and a base
6.
The front and rear faces 4 and 5 are at an inclined
angle to the vertical of approximately as is shown
15 taper.
There is a second platform portion 7 and behind
this a rearward facing face 8.
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~, .
The mo~ing or male portion of the die 9 as a protrud-
ing shape portion 10 which includes a base portion
11, a forwar~ face 12 and a rearward face 13, thes~
being corr~spondingly i.nclined one with respect to
the other to.match with appropriate metal therebetween
the depression 3.
The metal sheet 14 has an ungrooved end 15 resting
on support 16 and at the other end of the assembly
the sheet 17 is retained in an interlocking position
as is shown in Figure 1 by retainer 18.
The dies are located in a conventional. brake of
conventional design so that upon successive coming
together of the dies 1 and 9 there will be formed a
further groove of elongated constant cross-sectional
shape as illustrated in Figure 2.
By reason o~ the interlocking of the sheet 14
especially by h~lvill~, a rearward facing face 8 of the
female die 1 engaging against the forward facing side
19 of the front side 20 of a previously formed groove,
as well as having the sheet~ ~.lt 17 held by member 18,
this ensures that as the (I-i.e 9 engages the metal, this
pulls the sheet from encl 1~ Eor the urther formation
of the groove.
Subsequent to the steps shown in Figures 1 and
2, the metal sheet is lifted from the interlocking
position shown in Figure 2 so that the sheet 14 is
then disp].aced by the depth of the groove and the sheet
is then equivalent to the position as shown in Figure
1 and the operation is repeated.
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Subsequent to all of the grooves being formed,
these are then caused to have cut in the base portion,
screening slots which are being cut in alignment wi.th
the groove shape and subsequent to this each o.E sheets
thus grooved and cut are rolled so that their outer
surface, that is the base portion is outermost in the
cylindrical shape and the grooves being previ.ously
elongate are now formed so as to form a circular shape
with successive grooves then being in coaxial alignment
with each having their circular shape.
In a preferred instance, the grooves are approximately
one centimetre deep and one centimetre across the base
and the rounded edges are as is shown in the drawings
and that the metal sheet selected can be made from
either 16 through to 24 gauge metal.
The method Or l-nan~lfacture of screens in this manner
has dramatically ;.nlpl~oved, the cost previously incurred
in the man~lfacture of such articles and has been a
very signi~:icant improvem~rlt in the art.
