Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to an apparatus for trans~
porting a sheet of a flexible material between a first and a
second position. In particular, and in a preferred embodi-
ment, the invention provides an apparatus for transporting a
lead strip of paper web from the dryer of a paper-making
machine to the first pass of a calender of the machine.
United States patent ~o. 3,355,349 issued on
November 28, 1967 describes an apparatus for transporting a
lead strip of paper web from the dryer of a paper making
machine and feeding into the first pass of the calenders of -;
said machine. The apparatus comprises an elongated frame, a
air-pervious endless belt movably mounted on the frame and
having its upper run travelling from the dryer to the first
pass of the calenders. The belt is arranged to receive the
lead strip from the dryer. A vacuum chest having a perfor-
ated top extends longltudinally of and below the upper run
of the belt. There are means for evacuating air from the
chest so as to apply a vacuum at the undersurface of the ~-
belt and thus cause the lead strip to cling to the belt. ~ ~
Air blast means beneath, and extending transversely of, the ~ ~ -
upper run of the belt are positioned at the discharge end.
These air blast means direct a blast of air upwardly through
the belt to lift the lead strip from the belt and extend the
lead strip towards the first pass of the calender. Thus,
the apparatus described in the above United States patent is
provided with means for ensuring that the lead strip is ;
temporarily attached to the belt and with means to ensure ;~
that the lead strip can leave the belt at the appropriate
time.
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These contradictory requirements of the apparatus
have provided difficulties.
The apparatus works well in most clrcumstances but
it has been found that as the weight of the paper is reduced ~ `~
it is necessary to increase the under belt a:ir blast pressure,
that is the means for separating the paper web from the belt
at the end of the run, to maximum. Even then increasing of
this pressure was found inadequate for certa:in grades of `
paper and single sheet tissue could not be projected at all
and followed round the discharge pulley.
An analysis of this system indicated that at
higher speed air entrained in the belt held the sheet to the
pulley system. The present invention seeks to avoid this
disadvantage and to provide an improvement in the apparatus
o~ ~he above ~nited States patent 3,355,3~9.
Accordingly, in one aspect, the present invention
is in an apparatus for transporting a sheet of dry paper
between two structures spaced from each other, the apparatus
including an elongated frame, an air-pervious endless belt
movably mounted on first and second pulleys positioned at
each end of the frame, the belt having its upper rung
travelling from the irst pulley, adjacent one structure,
to the second pulley, adjacent the other structure, and ~ `
arranged to receive a lead strip of the sheet from the one
structure, a vacuum chest having a perforated top extending
longitudinally of and below the upper rung of the belt,
means for evacuating air from the chest in order to apply a
vacuum at the undersurface of the belt and thereby cause the
lead strip to cling to the belt, and is the improvement
comprising: a nose shoe disposed beyond the second pulley
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and spaced slightly from the second pulley to define an ;
opening between the shoe and the second pulley where the
sheet leaves the belt, an inlet into the shoe to receive a -
supply of air, at least one first air jet means disposed in ;~
the nose shoe adjacent the second pulley whereby a first air
jet may be directed into the opening and against the sheet
in a direction contrary to the rotation of the second pulley
sufficient both to overcome any gripping effect of air
entrained within the air~pervious belt and to lift the sheet
of flexible material; and second air jet means attached to
the nose shoe on that side of the shoe remote from the
second pulley and able to direct air downstream of the shoe
to act as a platform for the sheet.
The above apparatus has been ound to be effective ~;
with paper o the heavier basis weights. The system is able
to project such paper forward and, by varying the air flow,
may control the angle of trajec~ory in relation to the belt
face. Because of the second air jet means, downstream from
the first air jet means the apparatus is also effective with
lightweight tissues. The second air jet means is preferably
provided with holes that are small in diameter to give a
velocity 10w with minimum air volume. The tissue sheet
will not fall through this air stream until the stream is
too weak to provide support. ~
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The invention is illustrated, by way of example,
in the accompanying drawings in which: ;
Figure 1 is a partially exploded view illustrating
the prior art;
Figure 2 is a plan view of the modifications
according to the present invention; and
Figure 3 is a side elevation of th~e modification
illustrated in Figure 2.
In Figure 1 an apparatus is illustrated comprising
a dryer 10 and calenders 12. The dryer 10 and the calenders
12 are of known construction, forming no part of the present
invention, so that their construction is shown somwhat
diagrammatically.
The dryer 10 is mounted on a base 14 secured to
lS the floor 16. The floor 16 is provided with an opening 18
which permits the paper web, in the event o a breakage, to
pass downwardly through the floor into a waste bin (not
shown) provided beneath the opening 18.
Calenders 12 comprise a plurality of rolls 20 -
mounted on a frame 22 one above the other. The paper web
normally passes from the top 24 of the dryer 10 into a first ~
pass 26 in the calenders 12. The dryers and calenders a~e ~-
both driven by conventional means (not shown) and are
provided with conventional controls so that the peripheral
speed of each of them may be synchronozed to control the
tension in the web.
An endless beIt type conveyor 28 extends between ~-
the dryer 10 and the calenders 12. The conveyor 28 carries
the lead strip between the dryers 10 and the calenders 12.
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At the calenders 12 the web is released to the
first pass 26 so that it may be caught in the pass 26 and
passed in the usual manner around the rolls 20 of the
calenders 12.
The conveyor 28 comprises an endless belt 29 that
extends between a pair of belt pulleys 30 and 31 mounted on
shafts 32 and 33, respectively. Shaft 33 is secured for
rotation between the opposite ends of a pair of spaced,
parallel support frames 34 (only one of which is shown~.
Shaft 33 projects at one end 35 beyond the frame 34 and is
provided with a small V-pulley 36 driven by a V-belt 37. -~
The V-belt 37 passes over a V-pulley 38 which is secured
concentrically to one of the calender rolls for rotation
with the roll. One of the V-pulleys 36 or 38 is of the ;`
variable diameter type so that the linear speed of the belt
may be synchronized with the peripheral speed o~ the calender
roLls.
Belt tensioners 39, which bear upwardly against a
lower run 40 of the belt 29, are secured between the frames
34. The belt tensioners are of known construction and are
not therefor described here.
Side frames 34 are connected to the vertical sides
o~ an elongated chest 41. Chest 41 is located between the
lower run 40 of the belt 29 and its upper run 42. Chest 41
~5 extends longitudinally of the conveyor belt 29 from a point -
adjacent pulley 30 to a point adjacent pulley 31. The chest
has an upper wall located adjacent to and parallel to the
upper run 42 of the belt. The upper wall is perforated.
The perforations may take any desired form, for example,
holes 43 (see Figure 3).
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The chest 41 is also provided with a conduit
extending from a vertical side and is connected by suitable
air line to a vacuum pump, an arrangement illustrated in
United States patent 3,355,349.
Extending transversely across the ~onveyor and
located beneath the belt and between the chest 41 and the ,~
pulley 31 is a perforated pipe 44 which is connected by
suitable conduits ~not shown) to an air pump (not shown).
The perforations in the pipe are arranged so that when air '~
pressure is supplied to the pipe the air blast issuing from
the perforation will be directed in a direction upwardly
against the underside of the belt and forwardly towards the
calenders 12. The pipe ~4 is held rigidly in place by
brackets.
Roller 45 is secured to the side frame 34. As
described' in United States Patent 3,355,349, the roller 45
is movable between a position in which the roller is pressed
downwardly upon the belt and a position in which it is
lifted upwardly from the belt.
The apparatus is also provided with a lead strip ~,
cutter 46.
Belt 29 is made of an air-pervious material, '
preferably a woven fabric. The weave is coarse so that the
space between the warp and welt will freely permit the
passage of air.
The conveyor 28 is supported on a framework 47 so
that the belt 29,,as it passes over pulley 30, lies inwardly
of the vertical plane 48 shown in dashed lines in Figure 1.
The plane 48 represents the position assumed by the paper
web when the web extends vertically downwardly from the
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periphery of the dryer 10 or from a doctor 49 as shown in
Figure 1.
In operation, the machine starts with the paper
web delivered as far as the last dryer of the paper making
machine and running vertically downward from the doctor 49,
through the opening 18 in the floor 16 and into waste.
A lead strip is formed in known manner at an edge
of the web lying above the conveyor. Due to the weight of
the paper, the lead strip passes over the upper run 42 of
the belt 29 and over the end portion of the chest 41 ad-
jacent pulley 30 and continue into the waste. The belt 29
is then placed in operation and the roller 45 extended
transversely across the belt 29. Air pressure is supplied
to pipe 44 and air is exhausted from chest 41. Vacuum
created in the chest results in the lead strip adhering to
the moving belt 29 and thus moving upwardly along the
conveyor 28. The portion of the lead strip now in the waste
bin is automatically severed by the cutter 46.
The lead strip is passed upwardly along the
conveyor and under the roller 45. It is lifted from the
beIt by an air blast issuing from the pipe 44 which extends
it towards the first pass 26 in the calenders 12.
When the grip of the calender upon the lead strip
is assured, roller 45 is released and vacuum in the chest 41
is eliminated. The lead strip is then widened in a normal
manner to the full width of the web.
As indicated above the use of the pipe 44 has
certain disadvantages with the lower weights of paper. The
present invention, which is illustrated in Figures 2 and 3,
overcomes these disadvantages.
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Figures 2 and 3 illustrate an embodiment of the
present invention, which is a modification of the apparatus
of Figure 1 in that the pipe 44 is dispensed with and
replaced by a shoe 50 spaced from the pulley 31 to define
an opening 51. This shoe functions as a shaped air receiver
to give maximum effect to air flow through jets 53. The
shoe 50 is provided with an inlet 52 that is adapted to
engage a source of compressed air. The shoe is provided
with angled outlets 53 able to direct zir through the
opening 51 between the second pulley 31 and the shoe 50.
The air is specifically directed in a direction contrary to
the direction of movement of the belt 29, that is contrary
to the direction of rotation of the pulley 31.
Figures 2 and 3 illustrate a preferred embodiment
of the invention tha~ i5 equipped wlth second air jet
means in the form of a pipe 54 provided with an inlet 55 and
with outlets 56 able to direct air downstream from the first
air jet means to act as a platform for a sheet moving down- -
stream of the shoe 50.
The pipe 54 is attached with collars 57, one at
each end of the pipe 54. These collars 57 can be slackened
on the pipe 54, for example, by the use of set screws (not
shown), so that the direction of air forced from the outlets
56 in the pipe 54 can be varied. The relative position of
the pulley 31 and of the upper surface 58 of the chest 41
should be noted. This positioning is such that there is a
gap of approximately 1/8 inch at 59, that is between the
belt and the upper surface 58 of ~he chest 41. Such a gap
is important in order to enable the system to operate
without vary rapid belt wear. The use of belt tensioners is
also necessary to maintain the necessary clearance.
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In an embodiment of the invention that has proved
useful the shoe 50 was formed with seventeen outlets 53 each
with a diameter of l/32 inch. There were six outlets 56
each with a diameter of l/16 inch. However, 1/32 inch
diameter outlets 56 also provided good results, and even
smaller outlets are preferred where they are adequate for
the transfer. The inlets 52 and 55 were threaded l/4 inch
normal pipe taper couplings. The vacuum chest cover 41 was
a "MICARTA" (trade mark) plate. The surface 51 was inclined
downwardly as illustrated in Figure 2 at an angle of 5 from
the horizontal. However, it should be emphasized that
these dimensions are not essential. Variations in them will
clearly be possible. It is simply essential that the amount
of air issuing from the outlets 53 be sufficient both to
overcome the efect of the air entrained within the pores of
belt 29 and, also, to lift the web above the upper surface
of the shoe 50.
The illustrated apparatus can be used without
forcing air through the outlets 56. If the paper is rel-
atively heavy it is found that the air jets through the
outlets 56 in pipe 54 are not necessary. These air jets are
only necessary with normal paper weights.
The air emitted through the outlets 53 is usually
of a varying velocity and volume but is dependent upon the
desired trajectory required of the sheet being transferred.
Air emitted through the outlets 56 in pipe 54 is preferably
of high velocity and low volumne. By increasing the velocity
of air the paper can be lifted higher.
The shoe 50 is provided with a bracket 60 formed
with openings 61 so that it may be mounted on the apparatus.
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A feature of the invention that can be parti-
cularly useful if there is a possibility of static elec-
tricity causing the paper to tend to cling to the shoe S0
is the provision of small outlets 62 in the upper surface
of the shoe 50. The holes 62 may direct air at an angle
to the surface or normal to the surface to overcome any
tendency of certain types of paper being attracted to the
surface by electrostatic charge.
The device of the present invention can be used -~
wherever it is desired to move a sheet of flexible material,
particularly paper, across a gap. This can be done simply
because it is required to move the sheet across a gap
between parts of a machine or it may be done deliberately,
for example, to scan a sheet of paper. The invention is of
particular importance where it is required to project a
paper tail across an openlng over which a scanner is posi-
tioned and send it to a position where the tail can be
picked up and fed to a reel.
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