Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1105507
The invention relates to an apparatus for slowing-down and over-
lapping sheets or sets of sheets to be deposited as a pile in a storage
means.
In a known apparatus of this type (German Patent Specifications
1 917 616 and 2 000 078) individual sheets delivered from a transverse cut-
ter are supplied to the storage means between upper ant lower conveyor belts.
On the feed path between the next to the last and the last lower belt of the
storage means, a braking device is provided in the form of a suction header
with suction holes which can be covered. By opening and closing the suction
holes in synchronism with the feed of sheets, this braking device acts on ~the
rear areas of the sheets. Since the sheet is not only retarded by the braking
'tevice, but also guided downwards, the beginning of the next following sheet
may slide over the preceding sheet, thus causing overlapping. The sheets
overlapped in this way are then conveyed further by the last lower conveyor
belt extending as far as the storage means and the upper .:onveyor belt possibly
extending over the storage means. When the apparatus is operating at maximum
capacity, despite the braking of the sheets achieved by the braking device,
the residual conveying speed is too great to ensure reliable prevention of
damage to the sheets due to striking of their front edges against the stop of
the storage means. On the other hand, to apply a greater braking effect with
the braking device would involve a substantial reduction in the capacity of
the apparatus.
The object of the invention is to provide an apparatus of the
aforesaid type, which can be operated at high capacity and in which there
is less danger of the sheets being damaged on their front edges due to
excessively hard impact on the stop of the storage means.
The invention provides apparatus for slowing down and overlapping
~- sheets o paper to be deposited as a pile in a storage means, the
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sheets being fed by conveying means from an inlet to the storage means at
a predetermined conveying speed, said apparatus including: a braking device
acting on the rear areas of the sheets and located below the conveying plane
and upstream of the storage means, the action of said braking device
being adjustable in relation to the conveying speed; said braking device
comprising a discharge roller provided with recesses and located directly
before the storage means, suction bars being located in the recesses in the
discharge roller and extending approximately to the crown thereof, blowing
nozzles being provided in the region of the discharge roller below said
bars to direct a flow of air towards the storage means.
Owing to the provision of the braking device directly before the
storage means, the sheets can be conveyed at maximum speed over virtually
the entire feed section. The combination of discharge roller with tangent
conveyor belts, suction bars and blowing nozzles ensures troublefree a~d
reliabl0 slowing down from the rear area of the sheet. The blowing nozzles
produce a cushion of air between the sheets already deposited and the sheet
being slowed-down, so that the sheet is slowed-down exclusively from its
rear area, floating on a cushion of air and is thus kept rigid. }-lowever,
the suction/braking device according to the invention not only allows a
higher capacity of the apparatus, but also facilitates a more compact
construction than the known a M aratus.
Preferably, the conveying means, in particular a conveyor belt
or set of conveyor belts located above the conveying plane extends into
the region of, in particular to the end of the storage means. This
embodiment thus assisSs conveyance of the leading edge of the sheet and
help to keep the sheet rigid during the braking process.
However, in this embodiment, since there is a tendency for the
sheets or sets of sheets to stick to the conveying means as a result of
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adhesion or of electrostatic charges, further blowing nozzles can be provided
directly before the storage means and below the conveying plane, which
nozzles have a blowing direction directed towards the rear areas of the
sheet to be tepositet and blowing nozzles may also be provitet above the
storage means in the front region of the latter, which nozzles have a blow-
ing direction pointing townwards onto the front areas of the sheet to be
deposited. In this case, the blowing nozzles blowing towards the rear
areas can be identical to the blowing nozzles below the suction bars in the
region of the tischarge roller. If the conveying means consist of spaced
individual belts or strips, the blowing nozzles, in particular blowing bars
are appropriately located in the gaps therebetween. An apparatus of this
type with nozzles blowing onto the rear ant front areas of the sheets can
not only be used in conjunction with the suction/braking device according
to the invention, but quite generally if the conveying means extend over
the storage means and there is a tendency for the sheets to stick to the
conveying means owing to adhesion or an electrostatic charge. In such
cases, the sheets are deposited in a Teliable and troublefree manner by
means of the blowing air.
An embodiment of invention is described in detail hereafter by
way of example only, with reference to the drawings wherein:
Figure 1 shows diagrammatically and in side view, an apparatus
for slowing-down and overlapping sheets to be conveyed to storage means;
Figure 2 shows to an enlarged scale a braking device of the
apparatus accorting to figure 1, directly preceding the storage means; and
Figure 3 shows the storage means of figure 1 in plan view.
Web material 3 is cut into individual sheets 4 by a transverse
cutter, consisting of an upper cutter roller 1 and lower cutter roller 2.
The sheets are conveyet in the direction of storage means 7 between upper
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and lower convcyor belts 5, G ~uided over rollers. ~ braking device 8 is
~rovidcd bclow the conve~ing plane between thc end of the lower conveyor
bclt (, (whicll prcfcrahly consists of several spaced apart individual belts)
and the storag~c ~cans 7. In order that the sheets arriving a~ a relatively
higll conveying spee~ do not follow the lower conveyor belts 6 at the rear
guide roller, lut pass into the braking device 8! a triangul~r hollow bar
9 is provided in the upper region of the guide roller on the discharge side~
By means of jets of air directed tangentially in the feed direction of the
guided conveyor belt 6, the bar effects parting of the front edges of the
sheets from this conveyor belt and urges them towards the conveyor belt 5,
the latter extending beyond the braking device ~.
The brakin~ device 8 (Figure 2) consists of a discharge roller
10, which is provided with a plurality of recesses 11. Like the teeth of
a comb, suction bars 13 provided with suction openings 12 connected to
a common suction header or box 14, project into these recesses 11. The
suction bars 13 extend approximately to the crown of the discharge roller
10 Below the suction bar 13, a blowing nozzle 15 is ~rovided in each
recess 11 J which nozzles blow in the direction of the storage means, i.e.
towards the rear areas of the sheets to be deposited. The discharge roller
10, suction bars 13 with the common suction box 14 and the blowing nozzles
15 are located in a common support 16 and are ver~ically adjustable by means
of an eccentric 17 (Figure 1).
The storage means 7 consists of a vertically movable platform 19
sUpporting a pallet 18, a stop 20 for the front edges of the sheets, lateral
guide plates 21 and a front vibrating plate 22.
The conveyor belt 5 ex~ending above the storage means 7 consists
of a plurality of individual belts spaced apart side~ y-side. Iocated
between the belts are blowing bars 23 with nozzles which blow downwards on
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the sheets to be deposited. l`he blowing bars 23 are supported by a common
hollow bar 24, through which they are supplied with air.
The apparatus illustrated operates as follows:
The sheets introduced into the feed section by the transverse cut-
ter are retained between the upper and lower conveyor belts 5, 6 and con~eyed
at a high speed in the direction of the storage means 7. By means of the
blowing air escaping from the hollow bar 9 at the end of the conveyor belts
6, the sheets are detached from the belts 6 and pressed against the extended
upper conveyor belt 5. While the front and central areas of the sheet are
passing over the braking device 8, the latter remains inoperative. It is
only actuated when the rear area is located above the braking device 8. To
effect this a sensor 25 (Figure 1~ is located on the feed section, which
sensor opens the suction openings 12 of the suction bars 13 through a
control device. The means by which the suction effect at the suction open-
ings 12 of the suction bars 13 is started and stopped, can be a laterally
movable slide plate 26, as is known from Ge~man Patent Specification
1 917 ~16. When the braking device 8 is actuated, the rear ends of the
sheets are sucked down onto the suction bars 13 and thus slowed-down. The
braking effect can be adjusted both by the level of the reduced pressure
in the suction box 14 as well as by the duration of the suction effect.
The sheets are only slowed to an extent such that after leaving the discharge
roller 10, their residual kinetic energy is sufficient to allow them to
reach the stop 20 without damage and to abut against the latter. The sheets
must also be guided reliably during braking. This guiding is effected by
the discharge roller 10 in conjunction with the conveyor belts 5, which are
tangential to the roller 10. To avoid the front edges of the sheets being
slowed-down before reaching the stop 20 by frictional contact with the
sheets already deposited, the blowing nozzles 15 deliver air between the
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moving sheet and the sheet already deposited, so that the moving sheet
floats on a cushion of air.
Thc hraking device is not actuated when the sheets are conveyed
at a lower speed, i.c. ~hen the machine is started-up. Only when a predeter-
mined conveying speed is exceeded is the sheet braked by reduced pressure
from the suction box 14. The speed at which braking is initiated depends
on the sheet material being handled. As the conveying speed increases, the
vacuum in the suction box is increased in proportion to the speed.
In this way it is ensured that the sheet can be conveyed reliably
to the stop at virtually any speed, but comes into contact with the latter
at a speed which does not damage the sheet.
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