Field of the Invention
[0001] The invention relates to dust extraction systems and web slitters equipped therewith.
Background to the Invention and Prior Art Known to the Applicant
[0002] The traditional dust extraction systems as used on the Applicant's slitter/rewinding
machines include dust extraction hoses attached at one end to the male knife and at
the other end to a fixed dust extraction manifold. A vacuum pump is provided to suck
the dust away from the blade along the dust extraction hoses into the dust extraction
manifold from where it is delivered to the dust collection vessel. The male knife
may be positioned anywhere along the male knife beam within the limits imposed by
the length of the dust extraction hose. Current dust extraction systems restrict the
lateral movement of a knife blade during automatic knife positioning and manual knife
positioning. The extraction hose of the prior art is secured in close proximity to
the blade of the male knife and to the extraction manifold by respective hose clamps.
These hose clamps are usually of the Chenny or Jubilee type. The extraction manifold
is normally secured to the male knife beam.
[0003] Whilst the prior art dust extraction systems have proved successful for a number
of years, the number of knives fitted to the machine typically match the number of
distinct extraction manifold fittings provided. Consequently, when the customer wishes
to add another knife he has to allow several hours downtime in order to modify the
extraction manifold and then purchase the spare parts to attach a new knife to the
manifold. Furthermore, when the customer wishes to remove a male knife, the revealed
unused manifold connection must be blocked to maintain the vacuum created in the extraction
manifold.
[0004] Furthermore, due to their inherent structure, the prior art dust extraction systems
require relatively unwieldy external hoses and clips. It is therefore a relatively
complex operation even to replace a knife blade with another kind of knife blade.
Furthermore, since a flexible hose is used to connect the male knife blade guard to
the extraction manifold, the flexible hose is extended every time the male knife is
engaged with the female knife or grooved roll and compressed every time the male knife
is disengaged with the female knife or grooved roll. The constant deflection of the
flexible hose makes hose failure a real possibility.
[0005] Within the current design, the hose used to link the knife holder to the manifold
restricts the movement of the knife thereby limiting the set-ups that can be achieved
with standard hoses. Extended hoses can be used to overcome this restriction but the
cost and complexity of handling the additional hose length safely is prohibitive.
[0006] Finally, relatively noisy, heavy and complex vacuum pumps are required to create
the suction in the manifold.
Summary of the Invention
[0007] In a first broad independent aspect, the invention provides a dust extraction system
for a web slitter incorporating one or more slitting blades; said system comprising
an extractor conduit which at its proximal extremity is in an area adjacent the slitting
operation and which at its distal extremity incorporates a head which engages with
an extraction manifold; and an extractor fan for causing the flow of extracted dust
from said proximal to said distal extremity;
characterised in that said manifold incorporates an elongate channel with means for sealing said head to
said extraction manifold; whereby said head may be positioned anywhere alongside said
channel.
[0008] This configuration is particularly advantageous because it avoids the traditional
requirement of one hole in the manifold for a particular hose end. Instead of discrete
positioning of the end of an extractor conduit, unlimited male knife positioning may
be achieved in the elongate channel. The requirements for potentially fiddly and complex
clips are avoided. The male knives may be added or removed quickly and simply without
the need for extensive technical assistance or spare parts other than the extra male
knife.
[0009] In a subsidiary aspect, the seal is formed from two oppositely positioned sealing
strips; whereby, in use, the relatively low pressure in the extraction manifold combines
with the relatively high ambient air pressure to push said portions against said head.
This configuration is particularly advantageous since it allows the strips to be relatively
straightforwardly parted for the removal of the head whilst at the same time allowing
a tight fit on the extraction head. Furthermore, it allows the knife blade to be positioned
in any appropriate position of the elongate channel. Consequently, downtime if any,
for the replacement of a knife blade is kept to the minimum with little or no requirement
for modification of the manifold.
[0010] In a further subsidiary aspect, the sealing strip portions are bowed. This increases
the surface area of contact between the inner portion of the sealing strips and the
head of the extraction system.
[0011] In a further subsidiary aspect, the head incorporates an upper aperture and laterally
extending fins. This configuration is particularly advantageous in terms of allowing
the parting of the sealing strips for the insertion or the removal of the head.
[0012] In a further subsidiary aspect, the fins are tapered. This further improves the ability
of the fins to be used in parting the sealing strips.
[0013] In a further subsidiary aspect, the fins are tapered in varying width from an upper
portion of the fins to a lower portion of the fins. This further improves the ability
of the fins being used to part the sealing strips.
[0014] In a further subsidiary aspect, the fins decrease in thickness in the lateral direction.
This provides a relatively pointed lateral extremity for the fins further facilitating
the parting of the sealing strips.
[0015] In a further subsidiary aspect, the fins are rounded. This configuration is particularly
advantageous in terms of removing the sharp edges which may otherwise damage the air
tightness of the extraction manifold.
[0016] In a further subsidiary aspect, the extractor conduit incorporates a rigid telescopic
portion. This configuration is particularly advantageous as it limits the degree of
motion other than in the telescopic direction. In preferred embodiments, the internal
surfaces of the rigid telescopic portion are relatively smooth which reduces the level
of turbulence and consequently noise during the suction process.
[0017] In a further subsidiary aspect, the extraction manifold is directly mounted onto
a male knife blade beam.
[0018] In a further subsidiary aspect, the system further comprises Venturi holes through
said extraction manifold which are aligned with holes provided through the male knife
blade beam. This further improves the flow of air between the extraction manifold
and the male knife blade beam.
[0019] In a further subsidiary aspect, both the extraction manifold and the fan are mounted
onto the male knife blade beam. This further improves the suction properties of the
dust extraction system.
[0020] In a further independent aspect, the invention provides a web slitter comprising
a dust extraction system according to any of the preceding aspects.
Brief Description of the Figures
[0021]
Figure 1 shows a side view of a male knife equipped with a first embodiment of the
invention.
Figure 2 shows a perspective view of a first embodiment of a dust extraction system.
Figure 3 shows a cross-sectional view of a dust extraction manifold according to the
first embodiment of the invention.
Figure 4 shows a side view of a second embodiment of a dust extraction system.
Figure 5 shows a front view of a male knife beam equipped with a plurality of extractor
conduits at various locations along the length of the dust extraction manifold.
Figure 6 shows a perspective view of the dust extraction manifold of the second embodiment
of the invention.
Figure 7 shows a cross-sectional view of the dust extraction manifold and male knife
beam in accordance with a further embodiment of the invention.
Figure 8 shows three separate configurations of the head of an extractor conduit in
accordance with any of the embodiments of the invention.
Detailed Description of the Figures
[0022] Figure 1 shows a knife blade assembly 1 equipped with a dust extraction system generally
referenced 2. The dust extraction system incorporates an extractor conduit which at
its proximal extremity 3 is in an area adjacent the slitting operation and which at
its distal extremity incorporates a head 4 which engages with extraction manifold
5. The extractor conduit 2 incorporates a telescoping extraction tube 6 and a manifold
seal deflector 7. The telescoping extraction tube 6 extends laterally whilst the manifold
seal deflector 7 extends upwardly. The telescoping extraction tube 6 and the deflector
7 are joined together by a tube section 8 provided at an angle. The deflector is secured
onto the mounting plate 9 by the mounting plate 10. Releasable attachment means such
as fasteners 11 and 12 immobilise the deflector relative to the plate 9.
[0023] The telescoping extraction tube 6 incorporates a number of concentric tubular portions
which slide relative to one another in order to achieve a lengthening or a shortening
of the tube. The central portion 13 of the telescoping extraction tube provides a
relatively smooth internal surface.
[0024] The manifold seal deflector 7 provides a substantially oblong internal cavity through
which a mixture of air and dust travel upwards. The upper extremity of the deflector
incorporates a head 4 which has at least one but preferably two laterally extending
fins 14 and 15. These fins are wedge shaped and reduce in thickness towards their
distal extremities 16 and 17. Alternative head configurations are presented in Figure
8 where distal extremities 18 and 19 are rounded, distal extremities 20 and 21 progressively
increase in width and, extremities 22 and 23 where a reduction in width is provided
from an upper portion to a lower portion. The head of the manifold seal deflector
has tapered ends machined perpendicular to maximise the sealing efficiency when traversing
the manifold seals 24 and 25.
[0025] As can be best seen in Figure 3, the seal is formed of two sealing strips 24 and
25 which are upwardly bowed and abut each other at their distal extremities. The sealing
strips will be of inherently flexible material in order to accommodate the insertion
of the fins of the head. The sealing strips fit tightly in an elongate channel generally
referenced 26. The dust extraction manifold 5 may be mounted onto the male knife beam
27 through releasable attachment means 28 and 29. The extraction manifold may be substantially
U-shaped. An aperture 30 may be provided between the extraction manifold and the male
knife beam 27. Extractor fans may be provided on at least one side of the male knife
beam as shown for example in Figure 5 where pumps 31 and 32 can draw air from the
internal cavity of the male knife beam 27.
[0026] When the male knife is positioned, the tapered ends of the head part the seal gradually,
preventing loss of air from the dust extraction manifold. Sealing is increased by
flowing air (low pressure) in the dust extraction manifold exerting an upward "pull"
on the seals forcing them against the head of the extraction system whilst the ambient
air (high pressure) push the seal onto the head. The length of the taper offers least
resistance and best sealing efficiency.
[0027] The dust extraction manifold 5 may be formed of two parts 33 and 34. These parts
may be light alloy extrusions. Each light alloy extrusion may have the facility to
accommodate sealing strips as shown in the previous figures. The ends of the dust
extraction manifold may be closed by a closure plate or other appropriate closure
means. As shown in Figure 3, the dust extraction manifold 5 is mounted directly onto
the male knife beam 27. The holes machined through the dust extraction manifold align
with the holes machined through the male knife beam.
[0028] A control mechanism may be provided so that when the slitting operation starts, the
extractor fans start. The air being expelled from the plenum chamber is replaced in
equal volume by air being sucked into the telescoping extraction tube.
[0029] The volume of air being sucked into the telescoping extraction tube takes with it
the dust created by the slitting action of the knives. The air passes through the
telescoping extraction tube into the manifold seal deflector and into the dust extraction
manifold. The smooth internal surfaces of the telescoping extraction tube produce
a fast, laminar air flow that maximises dust extraction. The extractor fans draw the
air out of the dust extraction manifold into the plenum chamber. From the plenum chamber,
the air/dust mixture is expelled from the extractor fans into a dust collection vessel
(not shown). The dust extraction is illustrated by arrows 35 and 36.
[0030] As can be best seen in Figure 5, a number of deflectors may be positioned along a
part of a dust extraction manifold.
[0031] A further embodiment of the invention is illustrated in Figures 4, 6 and 7. Identical
numerical references to the first embodiment are employed throughout for simplicity
other than for parts which differ from the corresponding parts in the first embodiment.
In Figures 4 and 6, the telescoping extraction tube of the first embodiment has been
replaced by a flexible hose 37 which connects the male knife blade guard 38 to the
manifold seal deflector 7.
[0032] As shown in Figure 7 dust extraction manifold 5 is mounted directly onto the male
knife beam 39. Venturi holes 40 machined through the dust extraction manifold 5 align
with holes machined through the male knife beam 39. The Venturi holes improve dust
extraction by accelerating the airflow into the plenum chamber.
[0033] When the machine starts, the extractor fans start. The air being expelled from the
plenum chamber is replaced in equal volume by air being sucked into the flexible hose.
The volume of air being sucked into the flexible hose takes with it the dust created
by the slitting action of the knives. Air passes through the flexible hose, into the
manifold seal deflector, and into the dust extraction manifold. The extractor fans
draw the air out of the dust extraction manifold into the plenum chamber. From the
plenum chamber, the air/dust mixture is expelled from the extractor fans into the
dust collection vessel.
[0034] In certain embodiments at least the following advantages are achieved:
- unlimited male knife positioning;
- simplified operation for changing the extraction hose attached to the male knife;
- male knives are added or removed quickly and simply without the need for technical
assistance or spare parts other than the extra male knife;
- the number of male knives is only limited by the length of the male knife beam;
- a positive flow dust extraction manifold system;
- no external pipes or hoses connecting the male knives to the dust extraction manifold;
and
- centrifugal blowers which are lighter and quieter.
1. A dust extraction system for a web slitter incorporating one or more slitting blades;
said system comprising an extractor conduit which at its proximal extremity is in
an area adjacent to the slitting operation and which at its distal extremity incorporates
a head which engages with an extraction manifold; and an extractor fan for causing
the flow of extracted dust from said proximal to said distal extremity; characterised in that said manifold incorporates an elongate channel with means for sealing said head to
said extraction manifold; whereby said head may be positioned anywhere along said
channel.
2. A system according to claim 1, wherein said seal is formed from two oppositely positioned
sealing strip portions; whereby, in use, the relatively low pressure in the extraction
manifold combines with the relatively high ambient air pressure to push said portions
against said head.
3. A system according to claim 2, wherein said sealing strip portions are bowed.
4. A system according to any of the preceding claims, wherein said head incorporates
an upper aperture and laterally extending fins.
5. A system according to claim 4, wherein said fins are tapered.
6. A system according to claim 5, wherein said fins are tapered and vary in width from
an upper portion of said fins to a lower portion of said fins.
7. A system according to either claim 5 or claim 6, wherein said fins decrease in thickness
in the lateral direction.
8. A system according to any of claims 4 to 7, wherein said fins are rounded.
9. A system according to any of the preceding claims, wherein said extractor conduit
incorporates a rigid telescopic portion.
10. A system according to any of the preceding claims, wherein said extraction manifold
is directly mounted onto a male knife blade beam.
11. A system according to claim 10, further comprising Venturi holes through said extraction
manifold which are aligned with holes provided through said male knife blade beam.
12. A system according to either claim 10 or claim 11, wherein both said extraction manifold
and said fan are mounted onto said male knife blade beam.
13. A web slitter comprising a dust extraction system according to any of the preceding
claims.
Amended claims in accordance with Rule 137(2) EPC.
1. A web slitter comprising a dust extraction system (2); said dust extraction system
incorporating one or more slitting blades; said system comprising an extractor conduit
(2) which at its proximal extremity (3) is in an area adjacent to the slitting operation
and which at its distal extremity incorporates a head (4) which engages with an extraction
manifold; an extractor fan for causing the flow of extracted dust from said proximal
(3) to said distal extremity; and an elongate channel (26) with means for sealing
said head (4) to said extraction manifold (5); whereby said head (4) may be positioned
anywhere along said channel (26); characterised in that said manifold (5) is mounted onto a male knife beam (27); said manifold (5) incorporating
Venturi holes (40) aligned with holes provided through said male knife blade beam
(27).
2. A system according to claim 1, wherein said seal is formed from two oppositely positioned
sealing strip portions (24,25); whereby, in use, the relatively low pressure in the
extraction manifold (5) combines with the relatively high ambient air pressure to
push said portions (24, 25) against said head (4).
3. A system according to claim 2, wherein said sealing strip portions (24,25) are bowed.
4. A system according to any of the preceding claims, wherein said head (4) incorporates
an upper aperture (30) and laterally extending fins (14,15).
5. A system according to claim 4, wherein said fins (14,15) are tapered.
6. A system according to claim 5, wherein said fins (14,15) are tapered and vary in
width from an upper portion of said fins to a lower portion of said fins.
7. A system according to either claim 5 or claim 6, wherein said fins (14,15) decrease
in thickness in the lateral direction.
8. A system according to any of claims 4 to 7, wherein said fins (14,15) are rounded.
9. A system according to any of the preceding claims, wherein said extractor conduit
(2) incorporates a rigid telescopic portion.
10. A system according to any of the preceding claims, wherein both said extraction manifold
(5) and said fan are mounted onto said male knife blade beam (27).