AN APPARATUS FOR CUTTING A WEB WITH A WATER JET

COUPE-VOILE AU JET D'EAU

English Abstract

The invention relates to an apparatus particularly for cutting a web with a water jet. The apparatus comprises support and positioning elements and a cutter head supported by them and extending to the edge part of the web (14) in the operating position. The cutter head comprises a support surface (13) provided with e.g. nodules (13.1-13.4) and at least one nozzle (28), which is so set that the edge part travels between the support surface (13) and the nozzle (28).

French Abstract

L'invention se rapporte à un appareil particulièrement destiné à couper une bande au moyen d'un jet d'eau. L'appareil comprend des éléments de soutien et de positionnement, et un porte-lame soutenu par eux et s'étendant à la partie de l'extrémité de la bande (14) dans la position de fonctionnement. Le porte-lame comprend une surface de soutien (13) fournie avec par exemple des nodules (13.1-13.4) et au moins une buse (28), qui est ainsi réglée, de sorte que la partie du bord se déplace entre la surface de soutien (13) et la buse (28).

Claims

CLAIMS

1. An apparatus particularly for cutting a web by means of a water jet
comprising
- a cutter head that extends to the edge area of the web (14) in the operating
position,
- a support surface (13) in the cutter head adaptable at least beneath the
edge
part,
- at least one nozzle (28) in the cutter head above the edge part for forming
a
cutting jet by means of high-pressure water, the nozzle (28) being so set that
the edge part travels between the support surface (13) and the nozzle (28) for
cutting a trim (54) from the paper web (14),
- support and positioning elements for supporting the cutter head and for
adjusting the nozzle (28) and the support surface (13) in the cross direction
of
the web (14), and
- a connection set below the support surface (13) and opening in the direction
of the cutting jet for collecting and removing cutting water from the
apparatus,
- an opening (84) arranged on the support surface (13) at the jet impact point
(84) for leading the cutting jet to the said underneath connection,
characterized in that the support surface (13) comprises elements (13.1-13.4)
providing an air gap for leading the air between the web and the support
surface (13) to the said opening.
2. An apparatus according to claim 1, characterized in that the support
surface
(13) has nodules (13.2).
3. An apparatus according to claim 1, characterized in that the support
surface
(13) has flat rivets (13.1 ).
4. An apparatus according to claim 1, characterized in that the support
surface
(13) has cavities (13.3).
5. An apparatus according to claim 1, characterized in that the support
surface
(13) has grooves (13.4).




6. An apparatus according to any of claims 1-5, characterized in that it
comprises
an ejector (18) set beneath the nozzle in the said connection, with an
essentially uniform diameter in the suction area.
7. An apparatus according to any of claims 1-6, characterized in that it
comprises
a forward blow (19) directed to beneath the web (14) towards the cutting
point.

Description

CA 02487208 2004-11-09
AN APPARATUS FOR CUTTING A WEB WITH A WATER JET
This invention relates to an apparatus for cutting a web with a water jet, the
apparatus comprising support and positioning elements and a cutter head
s supported by them and extending in the operating position to the web edge
area,
the cutter head comprising a support surface, adaptable at least beneath the
edge
part, and at least one nozzle above it for forming a cutting jet with high-
pressure
water, the nozzle being so set that the edge part travels between the support
surface and the nozzle for cutting a trim from the web. Here the web is
generally a
io paper web.
Finnish publication No. 98346 discloses an apparatus for cutting the edge of a
paper web. For the actual cutting the apparatus comprises here a nozzle for
forming a cutting jet with high-pressure water and a plane adapted beneath the
nozzle. In the cutting situation the web travels between the nozzle and the
plane
is whereat the water jet cuts the web. For the cutting jet, the plane is
provided with
an opening and discharge connections at the opening below the plane for
removing the cutting water from the apparatus. The plane is also called a
table,
the location of which together with the nozzle can be adjusted in the cross
direction of the web.
Zo Publication EP870583B1 sets forth an apparatus for cutting a trim, in which
the
support plane is a separate item being formed of a ceramic material.
Known solutions involve the risk that the opening in the support plane gets
blocked
eventually. This causes a web break.
The objective of the invention is to provide an improved apparatus
particularly for
2s cutting a web with a water jet without the above-mentioned disadvantage.
The
features characterizing this invention become evident from the appended
claims.
The apparatus according to the invention comprises several alternatives.
Blocking
is avoided by leading compensating air to the opening for keeping the
apparatus
clean and thus for preventing the formation of a blister.


CA 02487208 2004-11-09
The invention is described below in detail by making reference to the enclosed
drawings, which illustrate some of the embodiments of the invention, in which
Figures 1 a -1 d illustrate various methods of providing a construction that
creates an air gap in the support plane.
Figure 2 is a top view of a water cutting apparatus.
Figure 3 is a side view of another water cutting apparatus.
The apparatus of Figure 2 is a modification of the solution disclosed in
publication
EP 87058381. Here the apparatus comprises support and positioning elements,
which are formed of a support arm and a guide construction adapted to it (not
io shown). The support arm is attached to a suitable position in a paper
machine and
generally on both sides of the web. In addition to a paper machine, the
apparatus
can also be used in connection with board machines and similar for cutting
even a
thick web.
The cutter head comprises a support surface 13, adaptable at least below the
is edge part, and at least one nozzle 28 above it for forming a cutting jet by
means of
high-pressure water. Deviating from the EP document, here the nozzle is
arranged
perpendicularly against the web. The cutter head is so arranged that the edge
part
travels between the support surface 13 and the nozzle 28, whereat a trim 54 is
cut
off the paper web 14. The cutter head additionally comprises connections for
2o removing the cutting water and the trim 54 from the apparatus. With the
cutting
water, part of the remains of cutting is also removed. On the support surface
13,
there is an opening 84 at the impact point 52 of the water jet, and beneath
the
opening a connection arranged in a known manner for collecting off the jet.
The
support surface 13 is supported to the frame 78. A compressed air nozzle 75,
Zs used for removing the mist from the cutting area, is arranged behind the
water
nozzle 28.
The invention is related to the cutter head of the apparatus and particularly
to
keeping clean the support surface 13, which allows avoiding disturbances
caused
by the cutting procedure. To prevent blocking of the opening, compensating air
is


CA 02487208 2004-11-09
led thereto from between the paper and the support surface. For this purpose,
at
least in the vicinity of the opening there are nodules, cavities, ridges or
grooves
conveying air to the opening, and allowing the speed of the air flow to remove
the
remains of cutting from the opening. The nodules or ridges are harder than the
surrounding.
According to Figures 1a-1d, the elements according to the invention conveying
the air flow to the opening are composed for example of nodules 13.2 formed in
the sheet, rivets 13.1 or the like embedded in the support surface, cavities
13.3 or
grooves 13.4, which are preferably set radial to the opening. For these, the
io opening in the support surface for passing the shower is not shown. In one
embodiment, machine directional rods or wires are added in the environment of
the discharge opening producing the same effect as the grooves or nodules.
These rods or wires can be either fastened directly to the sheet surface for
example by welding or, for improving the fastening, the rods/wires can be
is connected to machine directional grooves. In one embodiment, 6 piano wires
(diameter 1 mm) were first welded on both sides at 5-mm interval in the
machine
direction with a 5-mm opening remaining between the center-most wires. In an
additional embodiment, besides the above-mentioned wires, one shorter wire was
welded at the center of them until to the opening from the web inlet
direction. The
2o ends of the wires are rubbed down for avoiding sharp edges.
In Figure 2 the support surface is provided with rivets 13.1, which are flat
in
relation to their width.
A more preferable solution than the above described is shown in Figure 3. The
nozzle 28 is here set perpendicular to the web 14. Reference number 13 refers
to
2s a support plane according to the invention comprising said nodules, rivets
or the
like for improving the air flow into the opening 84. This solution is
preferable firstly
due to a straight-tube ejector 18. The discharge pipe is uniform over a major
length and broadens finally at the bottom end, which prevents remains of fiber
from accumulating and blocking the discharge pipe.
3o Another preferable feature is a forward auxiliary flow 19 (so-called tail
shooter
type) in a relatively narrow area at the point of cutting.


CA 02487208 2004-11-09
It will be understood that the foregoing description is merely by way of
example,
and shall not be construed as limiting. Further changes in the structure which
would occur to a person skilled in the art are within the scope of the claims
without
departing from the spirit of the invention.

Representative Drawing