U.S. patent application number 10/204205 was filed with the patent office on 2003-09-11 for method and apparatus in unwinding.
Invention is credited to Kinnunen, Jorma, Naatti, Ilkka.
Application Number | 20030168548 10/204205 |
Document ID | / |
Family ID | 8557500 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030168548 |
Kind Code |
A1 |
Kinnunen, Jorma ; et
al. |
September 11, 2003 |
Method and apparatus in unwinding
Abstract
In the method in splicing in a continuous unwind, the surface
speed of a new machine reel (R2) which is brought to the unwind and
closed with a leading splice is accelerated in the initial
acceleration to make the speed correspond to the speed of the old
machine reel (R1) that is becoming empty, so that the fastening
splice of the new machine reel can be joined to the web of the old
machine reel. The loading affecting the leading splice and/or
fastening splice of the new machine reel (R2) during the initial
acceleration is reduced. The present invention also relates to an
apparatus for implementing the method.
Inventors: |
Kinnunen, Jorma; (Helsinki,
FI) ; Naatti, Ilkka; (Vantaa, FI) |
Correspondence
Address: |
STEINBERG & RASKIN, P.C.
1140 AVENUE OF THE AMERICAS, 15th FLOOR
NEW YORK
NY
10036-5803
US
|
Family ID: |
8557500 |
Appl. No.: |
10/204205 |
Filed: |
March 18, 2003 |
PCT Filed: |
January 31, 2001 |
PCT NO: |
PCT/FI01/00089 |
Current U.S.
Class: |
242/555.3 |
Current CPC
Class: |
B65H 19/1821 20130101;
B65H 2301/41361 20130101; B65H 19/1894 20130101 |
Class at
Publication: |
242/555.3 |
International
Class: |
B65H 019/18 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 15, 2000 |
FI |
20000320 |
Claims
1. A method in splicing in a continuous unwind, in which method the
surface speed of a new machine reel (R2) which is brought to the
unwind and closed with a leading splice is accelerated in the
initial acceleration to make its speed correspond to the speed of
an old machine reel (R1) that is becoming empty, so that the
fastening splice of the new machine reel can be joined to the web
of the old machine reel, characterized in that the loading
affecting a leading splice and/or fastening splice of the new
machine reel (R2) during the initial acceleration is reduced by
using active and/or passive actuators.
2. The method according to claim 1, characterized in that the
loading is reduced by directing air blows and/or suction to
suitable locations.
3. The method according to claim 2, characterized in that air is
blown towards a splicing gap (N).
4. The method according to claim 3, characterized in that air is
blown between contact points (N1, N2) restricting the splicing gap
in such a manner that the air blow is substantially parallel to a
tangent travelling via a contact point (N1) on the periphery of the
splicing roll (3) and a tangent travelling via a contact point (N2)
on the periphery of the new machine reel (R2).
5. The method according to claim 2, characterized in that air is
sucked from the splicing gap (N).
6. The method according to claim 5, characterized in that air is
sucked between contact points (N1, N2) restricting the splicing gap
in such a manner that the suction of air is substantially parallel
to a tangent travelling via a point (N1) on the periphery of the
splicing roll (3) and a tangent travelling via a point (N2) on the
periphery of the new machine reel (R2).
7. The method according to claim 2, characterized in that the blow
of air is directed in parallel to the surface of the new machine
reel (R2) against the direction of rotation of the machine
reel.
8. The method according to claim 2 or 7, characterized in that the
blow of air is directed in parallel to the web (W) coming from the
old machine reel (R1) against the direction of rotation of the
web.
9. The method according to claim 2, characterized in that the blow
of air is directed in parallel to the outer periphery of the new
machine reel (R2) close to the surface of the machine reel in the
direction of rotation of the machine reel.
10. The method according to claim 2, characterized in that the flow
of air is affected before the splicing gap (N) and/or after the
splicing gap (N) by means of mechanical obstacles.
11. The method according to claim 10, characterized in that the
obstacle is an article (7) shaped into a given form from a
sheet-like material.
12. The method according to claim 10, characterized. in that the
obstacle is a roll (8) arranged before the splicing gap, which roll
touches the web (W) when the web passes by the roll.
13. The method according to claim 1, characterized in that the
temperature of the fastening splice and/or leading splice is
adjusted to increase the adhesion of the splices.
14. An apparatus in connection with splicing of a web (W) coming
from an old machine reel (R1) and a web of a new machine reel (R2),
in which splicing said webs are arranged to be connected to each
other by means of a fastening splice, characterized in that the
apparatus comprises means for reducing the loading applied to the
leading splice and/or fastening splice of the new machine reel
(R2).
15. The apparatus according to claim 14, characterized in that the
means for reducing the loading applied to the leading splice and/or
fastening splice of the new machine reel (R2) comprise one or more
active or passive actuators.
16. The apparatus according to claim 14 or 15, characterized in
that the device/devices is/are one or more devices that blow or
suck air.
17. The apparatus according to claim 16, characterized in that the
device is a blow device (6) which is positioned after the splicing
gap and directed towards the splicing gap against the travel
direction of the surface of the new machine reel (R1) and the web
(W).
18. The apparatus according to claim 17, characterized in that the
blow device (6) is arranged to blow air towards the splicing gap
(N) between the contact points (N1, N2) in such a manner that the
blow of air is substantially parallel to a tangent travelling via a
contact point (N1) on the periphery of the splicing roll (3) and a
tangent travelling via a contact point (N2) on the periphery of the
new machine reel (R2).
19. The apparatus according to claim 16, characterized in that the
device is a suction device (9) which is located after the splicing
gap and directed towards the splicing gap against the travel
direction of the surface of the new machine reel (R2) and the web
(W).
20. The apparatus according to claim 19, characterized in that the
blow device (9) is arranged to suck air from the splicing gap
between the contact points (N1, N2) in such a manner that the
suction of air is substantially parallel to a tangent travelling
via a contact point (N1) on the periphery of the splicing roll (3)
and a tangent travelling via a contact point (N2) on the periphery
of the new machine reel (R2).
21. The apparatus according to claim 16, characterized in that one
or more devices are arranged to blow air before the splicing gap in
parallel to the surface of the new machine reel (R2) against the
direction of rotation of the machine reel.
22. The apparatus according to claim 16 or 21, characterized in
that the blow of air is directed in parallel to the web (W) coming
from the old machine reel (R1) against the travel direction of the
web.
23. The apparatus according to claim 16, characterized in that one
or more devices are arranged to blow air in parallel to the outer
periphery of the new machine reel (R2) close to the surface of the
machine reel in the direction of rotation of the machine reel.
24. The apparatus according to claim 14 or 15, characterized in
that one or more device/devices is/are one or more mechanical
obstacles placed between the splicing gap and/or after the splicing
gap.
25. The apparatus according to claim 24, characterized in that the
obstacle is an article (7) shaped into a given form from a
sheet-like material.
26. The apparatus according to claim 24, characterized in that the
obstacle is a roll (8) arranged before the splicing gap, which roll
touches the web (W) when the web passes by the roll.
27. The apparatus according to claim 14, characterized in that it
comprises means for adjusting the temperature of the fastening
splice and/or leading splice.
Description
[0001] The present invention relates to a method and apparatus in
unwinding. The invention relates to a situation preceding the
splicing stage in a continuous unwind, which terminates when the
web of a new machine reel brought to the unwind is attached at full
speed to the web of a machine reel that is becoming empty, by
pressing the web of the machine reel that is becoming empty against
a splice in the new machine reel, and the old web has been cut.
Unwinding devices and measures conducted in connection with the
reel change are described for example in Finnish patents FI 100323
and FI 101875.
[0002] In this application, the term leading splice is used to
describe the arrangement that keeps the web attached to the surface
of a new machine reel before splicing. The term fastening splice is
used to describe the arrangement that fastens the web of a new
machine reel to the web coming from the old machine reel that is
becoming empty. The leading splice and the fastening splice can
form two discrete sections, or they can be parts of the same
fastening arrangement. The leading splice and the fastening splice
can, for example, form the different sides of a two-sided adhesive
tape, if the tape is attached to the end of the web of a new
machine reel in such a manner that part of the tape extends over
the length of the web fixing the end of the web to the new machine
reel. In this application, the concept of a splicing gap refers to
the point extending on the entire width of the web between the new
machine reel and the splicing roll, in which point the distance
between the new machine reel and the splicing roll is the shortest.
In a splicing situation, the splicing gap is closed when the
splicing roll strikes against the surface of the new machine roll
to attain splicing. Furthermore, in this application the term
initial acceleration refers to the stage of accelerating the speed
of a full machine reel and/or the rotation of the same before
splicing.
[0003] In off-machine coating machines for paper, a continuous
unwind is used in which a new, full machine reel that is brought to
the unwind is attached to the end of the paper web in the machine
reel that is becoming empty. In present-day fast coating machines
the splicing method is essentially the same, i.e. a fastening
splice is prepared in the leading end of the web of a new machine
reel by means of a two-sided adhesive tape, coated with a binding
agent, the splice being attached on the surface of the reel by
means of a leading splice, for example with pieces of fastening
tape. The surface speed of the new machine reel is accelerated to
be equal to the running speed of the machine, i.e. to the web speed
of the paper web discharged from the machine reel that is becoming
empty, whereafter the web of the reel that is becoming empty is
pressed against the aforementioned fastening splice for example by
means of a roll or a brush. The old web is cut with a blade above
the splice.
[0004] In the splicing, the splicing roll is rapidly struck against
the surface of a new machine reel, wherein a tension peak occurs in
the web. The aim is to keep the tension peak caused by the stroke
of the roll on a low level, by using a small splicing gap (8 to 12
mm), which causes a strong phenomenon of negative pressure. Because
the present running speeds are very high, even over 1600 m/min,
situations easily occur in which the travel of the web is disturbed
and the web may break. Because the loading stressing the leading
splice is directly proportional to the square of the running speed,
and the adhesive attraction of the fastening splice is directly
proportional to the adhesion time, which, of course, is reduced
when running speeds are increased, it is obvious that splicing is
problematic at high running speeds.
[0005] The negative pressure which is generated in the splicing gap
between the splicing roll and the machine reel tends to draw the
old web partly against the fastening splice already before
splicing. The negative pressure may be pulsating when the new
machine reel is out of round. Furthermore, the negative pressure
tends to detach the leading splice from the surface of the new
machine reel, wherein the new machine reel is unwound before
splicing.
[0006] One solution for stabilizing the run of the web is presented
in the patent publication U.S. Pat. No. 5,779,184 and in the
corresponding European publication 0732287. By means of the method
according to the publication, the run of the web is stabilized in
such a manner that before the splicing gap there is a suction box,
equal in width with the web, and the web touches this suction box
when passing by the same. The suction is directed away from the
web, wherein the negative pressure keeps the web on the surface of
the suction box, thereby stabilizing its run. By means of this
arrangement, it is not, however, possible to eliminate all effects
of the negative pressure in the splicing gap.
[0007] It is an aim of the solution of the present application that
the end of a new machine reel remains attached to the surface of a
new machine reel by its leading splice, and that the new machine
reel endures the initial acceleration without being unwound. On the
other hand, the leading splice has to be detached easily when the
splicing roll is struck against the surface of the new machine
reel, and the fastening splice adheres to the web coming from the
old machine reel that is becoming empty, the old web is cut and the
discharge of the web from the new machine reel begins. A
substantially uniform loading is exerted on the leading splice on
the entire width of the web, which loading can, however, vary as a
function of time for example due to said pulsating negative
pressure. The loading exerted on the leading splice consists of the
loading caused by air friction, centrifugal tension and the tension
caused by the negative pressure in the splicing gap. In addition,
the fastening splice must have a good adherence capacity to the
web. Most significant part of the loading that exerted on the
leading splice is the tension caused by the negative pressure
prevailing in the splicing gap.
[0008] The tension caused by air friction can be calculated
according to the following formula
T.sub.fric={fraction
(1/2)}.multidot.C.sub.f.multidot..rho..sub.a.multidot-
.V.sup.2.multidot.I,
[0009] in which
[0010] T.sub.fric=tension caused by air friction (N/m)
[0011] C.sub.f=coefficient of resistance .about.0,0025
[0012] .rho..sub.a=air density (kg/m.sup.3)
[0013] v=running speed (m/s)
[0014] l=web length (m)
[0015] The centrifugal tension can be calculated according to the
formula
T.sub.CP=(M.sub.WEB+M.sub.AIR).multidot.V.sup.2,
[0016] in which
[0017] T.sub.CP=centrifugal tension (N/m)
[0018] M.sub.WEB=grammage of paper (kg/m.sup.2)
[0019] M.sub.AIR=mass of air conveyed by paper (kg/m.sup.2)
[0020] v=running speed
[0021] The tension caused by the negative pressure prevailing in
the splicing gap is calculated according to the formula
T.sub.VAC.apprxeq..DELTA.p.multidot.r,
[0022] in which
[0023] T.sub.VAC=tension caused by negative pressure (N/m)
[0024] .DELTA.p=the difference between the pressure of the splicing
gap and the pressure prevailing inside the reel (normal pressure),
i.e. the negative pressure (Pa) prevailing in the splicing gap
[0025] r=radius of the reel to be accelerated (m)
[0026] The negative pressure prevailing in the splicing gap is
calculated according to the formula
.DELTA..apprxeq.{fraction
(1/2)}.multidot..rho..sub.a.multidot.v.sub.a.sup- .2,
[0027] in which
[0028] .rho..sub.a=air density (kg/m.sup.3)
[0029] v.sub.a=flow rate of air in the splicing gap (m/s)
[0030] By means of the method and apparatus according to the
invention it is possible to affect the loading exerted on the
leading splice and/or fastening splice of the new machine reel. The
method is characterized in that the loading affecting the leading
splice and/or fastening splice of the new machine reel during the
initial acceleration is reduced. The apparatus is characterized in
that it comprises means for reducing the loading applied to the
leading splice and/or fastening splice of the new machine reel.
[0031] By means of the new high speed splicing arrangement
according to the invention, it is possible to considerably reduce
the loading exerted on the leading splice and/or fastening splice,
especially the negative pressure prevailing in the splicing gap.
Furthermore, it is possible to adjust the temperature of the
leading splice and/or fastening splice to adjust their
adhesion.
[0032] The effect of the loading exerted on the leading splice
and/or fastening splice, for example the tension caused by air
friction and the tension prevailing in the splicing gap, can be
reduced by passive and/or active actuators. By means of active
actuators the loading is reduced by producing counter loading for
said loading, and the passive actuators function as obstacles so
that the air current causing the negative pressure would not enter
the splicing gap. Generally, the actuators extend over the entire
width of the web, but it is also possible that the actuators only
extend on a part of the width of the web.
[0033] To reduce the tension caused by the negative pressure
prevailing in the splicing gap, the aim is to reduce or prevent the
generation of negative pressure. The generation of negative
pressure can be prevented or it can be reduced for example
[0034] by directing an air blow in the splicing gap, the direction
of which is substantially opposite to the flow direction of the air
flowing in the splicing gap. The amount of air blow is adjusted so
that the flow rate of air in the splicing gap is approximately
substantially zero, or
[0035] by arranging moving or stationary mechanical obstacles,
which prevent or reduce the generation of negative pressure in the
splicing gap, or
[0036] by directing air suction away from the splicing gap, the
direction of which is substantially opposite to the flow direction
of the air flowing in the splicing gap. The amount of air suction
is adjusted so that the flow rate of air in the splicing gap is
approximately substantially zero, or
[0037] by blowing air along the surface of a new, full machine reel
against the direction of rotation of the machine reel and/or by
blowing air along the surface of a web coming from the old machine
reel that is becoming empty against the travel direction of the
web.
[0038] The adhesion of the fastening splice to the web of the old
machine reel can be improved by adjusting the temperature of the
ambient air in the fastening splice and/or the temperature of the
fastening splice. The temperature of the ambient air in the
fastening splice and/or the temperature of the fastening splice can
be increased by means of infrared heating, by blowing heated air
from a blow box or the like, by microwave heating or inductively by
heating up the fastening splice that contains metal. The act of
reducing the negative pressure in the splicing gap and the heating
of the fastening splice can be combined in one actuator in such a
manner that the blowing of the heated air is arranged to a suitable
location from which air is blown to reduce the air flow in the
splicing gap.
[0039] The effect of the tension caused by air friction can be
reduced by directing air blows to suitable points in the direction
of the periphery of the new machine reel and in the direction of
rotation of the reel within a given section on the periphery, that
does not extend close to the splicing gap, in the vicinity of which
air is blown substantially against the aforementioned
direction.
[0040] In the following, the invention will be described with
reference to the appended drawings, in which,
[0041] FIG. 1 shows a side-view of a full machine reel,
[0042] FIG. 2 shows an unwinding apparatus and an embodiment of the
invention,
[0043] FIGS. 3 to 7 shows embodiments of the invention, and
[0044] FIG. 8 shows an arrangement to reduce air friction.
[0045] FIG. 1 shows a side-view of a full machine reel R2 that
enters the unwind. The drawing also shows as an example how leading
splices and fastening splices can be formed on the surface of the
full machine reel R2. The paper web is reeled around a reeling
shaft K, and the end E of the paper web W (marked with a dotted
line in the drawing) is attached to the surface of the reel R2 by
means of a leading splice P. The end E of the paper web W remains
underneath the splices according to FIG. 1. On the surface of the
reel R2 there is a ready-made fastening splice F, from which the
new machine reel R2 is attached to the end of the web W of an old
machine reel R1.
[0046] FIG. 2 shows a side-view of an apparatus whose splicing
arrangement is of the type presented in the Finnish patent 100323.
In the apparatus, the web W is continuously unwound from machine
reels brought to thereto, said machine reels being formed at an
earlier reeling stage, and the web W is guided to a finishing
apparatus of paper web, for example to a coating machine. The
apparatus comprises a secondary drive 2 which rotates the machine
reel R1 that is becoming empty and a primary drive 1 which rotates
a new, full machine reel R2 brought to the apparatus. The main
principle of the continuous unwinding is to bring reels
successively into the apparatus in such a manner that a full reel
is brought therein to be rotated by the primary drive 1, the paper
web of the reel is attached to the web W coming from the reel that
is becoming empty, which is rotated by the secondary drive 2, and
the web is cut, whereafter it is unwound from the full reel rotated
by the primary drive 1. When a particular amount of paper remains
on the reel rotated by the primary drive 1, the reel is transferred
to be rotated by the secondary drive 2, and a new full machine reel
is brought to the primary drive, whereafter the webs are attached
to each other again in the above-described manner. The transfer of
the full reel R2 to the primary drive 1, the removal of the empty
reel R1 from the secondary drive 2 and the change of the unwound
reel from the primary drive 1 to the secondary drive 2 can be
performed by using known solutions, and since they are not part of
the invention, they will not be described in more detail in this
context.
[0047] FIG. 2 describes a situation before the change, in which the
web of the full machine reel R2 that has been brought to a primary
station in the primary drive 1 is joined to a web W discharged from
the machine reel R1 that is becoming empty in the secondary drive
2. The circumference of the full machine reel R2 touches a splicing
station provided with a splicing roll 3 which guides the web W
discharged from the reel R1 that is becoming empty in close
proximity to the outer surface of the circumference in the full
machine reel R2 rotated by the primary drive 1, in such a way that
a splicing gap of a given width is formed between the web and the
machine reel R2. The splicing is performed by striking the splicing
roll 3 rapidly towards the opposite surface of the reel, wherein
the splicing gap is closed. The splicing stroke is synchronized by
striking the web W against the surface of the full machine reel R2
when the attachment point on the surface of the reel, for example a
splicing tape, enters the splicing station. This point is marked
with the letter S. The tape assembly in question can be for example
a tape assembly in the transverse direction of the web by means of
a tape whose both sides are adhesive, the tape assembly being
attached to the end of the web of a full machine reel R2, and it
typically has the shape of a saw blade or the like for the purpose
of improving the grip. Furthermore, the cutting of the web to be
discharged is conducted in a synchronized manner with the splicing
stroke by utilizing a cutting device illustrated by arrow C, which
cutting device performs the cutting stroke and is located before
the splicing roll 3 in the travel direction of the web. The cutting
device can be for example a striking blade cutting device. The
drawing also illustrates an auxiliary roll 4 cooperating with the
actual splicing roll 3 and guiding the discharged web W after the
splicing station (splicing gap). The auxiliary roll is attached
together with the splicing roll 3 to a common lever 5 articulated
at an articulation point 5a located between the axes of the rolls 3
and 4. When the splicing roll 3 is struck against the surface of
the full machine reel R2 by means of an actuator (not shown), the
motion is transmitted to the auxiliary roll 4 by means of the
lever, this motion of the auxiliary roll backwards along a path
determined by the point of articulation compensating the stretch
otherwise produced on the web.
[0048] FIGS. 2 and 3 show an embodiment of the invention, in which
air is blown to the splicing gap N from a blow device 6. From the
blow device 6 installed in the gap opening between the reel and the
web, air is blown in the direction of the arrow B towards the
splicing gap N against the travel direction of the periphery of the
reel R2 and the web W. During splicing, a contact point N1 on the
periphery of the splicing roll 3 and a contact point N2 on the
periphery of the new machine reel R2 enter in contact with each
other. The points N1 and N2 extend over the length of the splicing
roll 3 and over the entire width of the web W. In a normal running
situation there is a splicing gap N between these contact points N1
and N2 that extend over the entire width of the web W. The blow of
air is parallel to the tangent on the periphery of the splicing
roll 3 that travels via the point N1 and the tangent on the
periphery of the new machine reel R2 that travels via the point N2,
and it is substantially directed towards the splicing gap N between
the points N1 and N2. Air is blown at such a speed that the flow
rate in the splicing gap is substantially zero. Air is blown on the
entire width of the web from a slit orifice or the like, at a speed
which substantially equals the travel speed of the web W. Thus, it
is advantageous that the air inlet of the blow device 6 is equal in
size with the splicing gap N. The blow device 6 is connected to a
positive pressure air source, for example to an air compressor. The
blast pressure of the blow device 6 can be set as a function of the
running speed, i.e. the travel speed of the web W.
[0049] FIG. 2 also shows an arrangement by means of which it is
possible to measure and adjust the temperature of the air to be
blown to improve the adhesion of the fastening splice or to adjust
the adhesion of the leading splice and/or fastening splice. A
temperature sensor 12 measures the temperature on the surface of
the machine reel R2 and the adjustment device 13 for temperature is
arranged to adjust the temperature of the air to be blown on the
basis of the information obtained from the temperature sensor 12.
The temperature sensor 12 and the adjustment device 13 for
temperature are known as such, and therefore they will not be
described in more detail in this context. The binding agents of the
leading splices and fastening splices can be selected in such a
manner that their adhesion is different in the same temperature,
wherein the splices behave optimally in the splicing situation. For
example the adhesion of the fastening splice may be greater than
the adhesion of the leading splice in said temperature. The
temperature of the air to be blown can also be changed during the
period of time passed between the act of starting the initial
acceleration and the splicing. Thus, the air flow blown from the
device 6 can be utilized to affect both the flow conditions and the
temperature conditions in the splicing gap.
[0050] FIG. 4 shows an embodiment of the invention, in which
mechanical obstacles 7 are placed above and below the splicing gap
to prevent the generation of negative pressure. The cross-section
of the obstacles 7 can, for example, resemble the one shown in FIG.
4, but obstacles of other shapes are also possible. The
cross-section of the obstacles 7 shown in FIG. 4 has a shape of the
letter V with a rounded angle. The obstacles 7 are located above
and below the splicing gap, i.e. in the travel direction of the
periphery of the reel R2 and the web W before the splicing gap N
and after the splicing gap N. The ends of the obstacles, whose
cross-section has the shape of the letter V with a rounded angle,
are directed towards the splicing gap N, close to the space between
the points N1 and N2. One side of the obstacle 7 is close to the
surface of the new machine reel R2 and the other is close to the
surface of the web W. This way it is possible to reduce air flow in
the splicing gap, and thereby also the negative pressure. The
obstacles may be stationary or movable, wherein they can be
transferred away from their position after the splicing is
finished, or the position of the same can be changed for example
when the size of the machine reel changes. The number of the
obstacles may vary, and they extend over the entire width of the
web W.
[0051] FIG. 5 shows an embodiment, in which a moving obstacle is
placed before the splicing roll 3 on the opposite side of the web W
in the travel direction of the web W, which obstacle prevents or
reduces the generation of negative pressure in the splicing gap N.
The obstacle is a roll 8 which has a considerably smaller diameter
than the splicing roll 3, and it extends over the entire width of
the web W. The roll 8 touches the web W when the web travels passes
by the roll 8. The direction of rotation of the roll 8 is opposite
to the direction of rotation of the splicing roll 3, and at the
point closest to the new machine reel R2, the surface of the same
moves to a direction opposite to the direction of motion of the
surface of the machine reel, thereby preventing the flow of air
towards the splicing gap in the direction of the periphery of the
reel R2.
[0052] FIG. 6 shows an embodiment, in which air is sucked from the
splicing gap at a suitable flow rate in such a manner that the flow
rate of air in the splicing gap N is substantially zero. The
suction can be performed by means of a suction device 9 extending
over the entire width of the web, for example by means of a slit
orifice or the like. The suction device is positioned in the
closing gap formed by the reel and the web, close to the splicing
gap N, in such a manner, however, that it does not touch the new
machine reel R2, the splicing roll 3 or the web W. The slit orifice
or corresponding suction inlet/inlets are directed towards the
splicing gap. The suction is directed in such a manner that it is
parallel to the tangent on the periphery of the splicing roll 3
travelling via the point N1 and the tangent on the periphery of the
new machine reel R2 travelling via point N2, and it is
substantially directed away from the splicing gap N between the
points N1 and N2. The slit orifice or a corresponding structure
extends substantially over the entire width of the web. In FIG. 6
the direction of the suction is shown with an arrow A. The suction
device 9 is coupled to a negative pressure air source, for example
to a vacuum pump.
[0053] FIG. 7 shows an embodiment in which air is blown in the
directions shown by arrows B1 and B2, substantially in parallel to
the surface of the machine reel R2 and the web W in such a manner
that the blowing takes place against the direction of rotation of
the machine reel R2, and against the travel direction of the web W.
The blowing arrangement 10 can be for example a slit orifice or the
like, which is directed in a suitable manner and extends
substantially on the entire width of the web. The air currents B1
and B2 prevent the access of air currents accompanying the surface
of the reel and the web to the splicing gap.
[0054] FIG. 8 shows an embodiment the aim of which is to reduce air
friction. Outside the outer periphery of the new machine reel R2,
close to the surface of the reel, devices 11 have been arranged at
fixed intervals, which devices blow air in the direction of
rotation of the machine reel R2 and extend over the entire width of
the new machine reel R2. In FIG. 8, arrows B3 represent the
direction in which air is blown. The air blowing devices 11 are
basically of the same type with the blow arrangement 10, but they
can differ from each other as far as their operating parameters,
for example the flow rate of air or mass flow are concerned. As can
be seen in FIG. 7, there are several successive blow devices on the
sector of the periphery of the reel that begins approximately at an
angular distance of 180.degree. from the splicing gap and ends at a
distance of approximately 30.degree. from the same. The blow
devices are not normally located in the splicing gap. The blow rate
of air is advantageously substantially the same as the speed of the
web to be unwound.
[0055] The above-described facts do not restrict the invention, but
the invention may vary within the scope of the claims. The
mechanical obstacles can differ from those presented in this
application. The effect can also be produced solely by means of an
obstacle/obstacles located before the splicing gap or solely by
means of an obstacle/obstacles located after the splicing gap. The
blowing or suction of air can be directed in different ways. The
essential aspect is that the loading exerted on the leading splice
and/or fastening splice of the new machine reel during the initial
acceleration is reduced by means of an apparatus which is suitable
for this purpose.
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