U.S. patent number 3,661,703 [Application Number 05/023,588] was granted by the patent office on 1972-05-09 for decurling apparatus.
This patent grant is currently assigned to Westvaco Corporation. Invention is credited to Clifford D. Shelor.
United States Patent |
3,661,703 |
Shelor |
May 9, 1972 |
DECURLING APPARATUS
Abstract
Decurling apparatus for controlling the curl characteristics of
a web incorporates a pair of elongated decurling rollers over a
selected one of which the web may be drawn to produce a
modification of its curl tendency. The magnitude of the curl
tendency modification produced in the web is a function of the
sharpness of the angle at which the web is drawn over the selected
decurling roller. To vary the magnitude of the curl tendency
modification being produced, the position of the selected decurling
roller with respect to the web is varied to change the sharpness of
the angular path of the web over the decurling roller. A movably
mounted compensating roller over which the web is drawn is
repositioned in response to movement of the selected decurling
roller to compensate for the tendency of decurling roller movement
to change the overall web path length.
Inventors: |
Shelor; Clifford D. (Covington,
VA) |
Assignee: |
Westvaco Corporation (New York,
NY)
|
Family
ID: |
21816051 |
Appl.
No.: |
05/023,588 |
Filed: |
March 30, 1970 |
Current U.S.
Class: |
162/271;
162/270 |
Current CPC
Class: |
B65H
23/34 (20130101) |
Current International
Class: |
B65H
23/34 (20060101); D21f 007/02 () |
Field of
Search: |
;162/270,271 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kellogg; Arthur D.
Claims
I claim:
1. Apparatus for decurling a continuously advancing web
comprising:
a. a web path through said apparatus to be followed by a
continuously supplied web of thin sheet material;
b. a first fixed position station along said web path near the
entry thereof into said apparatus;
c. a second fixed position station along said web path near the
exit thereof from said apparatus;
d. a pair of elongated, substantially parallel, relatively spaced
decurling members disposed along, transversely of and oppositely
adjacent said web path between said first and second position
stations;
e. decurling member adjustment means for advancing said decurling
members along an adjustment path substantially, parallel to a plane
including the longitudinal axes of said decurling members, said
adjustment path also being substantially perpendicular to said
longitudinal axes, advancement in one direction from a neutral
position being effective to produce engagement between one of said
decurling members and one surface of said web to deflect said web
path in a first direction and impart to such web one modification
of its curl tendency and advancement from said neutral position in
the other direction being effective to produce engagement between
the other decurling member and the other surface of such web to
deflect the web path in a second direction and impart to such web
another modification of its curl tendency; and
f. web path compensation means movably disposed along said web path
between said first and second position stations and interconnected
to the movement of said decurling members in a manner such that the
linear distance along said web path between said first and second
position stations remains a substantially constant quantity.
2. Apparatus according the claim 1 wherein said web path
compensation means comprises:
a. a compensating roller;
b. means movably supporting said compensating roller adjacent said
decurling members so that such web may be drawn thereover
subsequent to passage of such web between said decurling members;
and
c. means linking said supporting means with said adjustment
means.
3. Apparatus according to claim 2 further comprising cam means
associated with said adjustment means and engageable with said
linking means for controlling movement of said roller means as said
decurling members are advanced.
4. Apparatus according to claim 3 wherein said decurling members
comprise a pair of cylindrical rollers rotatably mounted in spaced,
substantially parallel relationship, said rollers having a diameter
substantially smaller than the diameter of said compensating
roller.
5. Apparatus for decurling a continuously advancing web
comprising:
a. a pair of cylindrical decurling rollers mounted in spaced
relationship and with their longitudinal axes substantially
parallel to form a passage therebetween for such web;
b. means for advancing said decurling rollers along a path
substantially parallel to a line passing through the longitudinal
axes of said decurling rollers perpendicularly thereof, advancement
in one direction from a neutral position being effective to produce
engagement between one of said decurling rollers and one surface of
said web to deflect the web path in a first direction and impart to
such web one modification of its curl tendency and advancement from
said neutral position in the other direction being effective to
produce engagement between the other decurling roller and the other
surface of such web to deflect the web path in a second direction
and impart to such web another modification of its curl
tendency;
c. a compensating roller;
d. means movably supporting said compensating roller adjacent said
decurling rollers so that such web may be drawn thereover
subsequent to passage of such web between said decurling
rollers;
e. cam means associated with said advancing means for controlling
movement of said compensating roller as said decurling rollers are
advanced; and
f. means linking said supporting means with said advancing means,
said linking means including a cam follower engageable with said
cam means for imparting movement to said compensating roller in
response to advancement of said decurling rollers, said movement of
said compensating roller producing a change in web path geometry
which compensates for change in web path geometry resulting from
advancement of said decurling rollers to avoid change in web path
length during advancement of said decurling members.
6. Decurling apparatus for use with means for advancing a web
between a pair of predetermined loci comprising:
a. an elongated decurling member between said loci adjacent such
web for imparting curl tendency to such web;
b. means movably mounting said decurling member for advancing said
decurling member into engagement with such web to controllably
produce change in the path geometry of such web, the magnitude of
the curl tendency imparted to such web by said decurling member
being a function of web path geometry;
c. compensating roller means;
d. means movably mounting said compensating roller means between
said loci adjacent the path of such web to provide an adjustable
support for such web; and
e. cam means linking said means movably mounting said decurling
member and said means movably mounting said compensating roller
means for producing predetermined movement of said compensating
roller means in response to movement of said decurling member to
influence web path geometry in a manner which maintains the web
path length between said loci constant.
7. Decurling apparatus according to claim 6 wherein said decurling
member comprises a roller having a diameter which is small relative
to the diameter of said compensating roller.
8. Decurling apparatus according to claim 6 further comprising a
second elongated decurling member spaced from the first said
decurling member and disposed substantially parallel thereto to
provide a passage for such web between said decurling members.
9. Decurling apparatus according to claim 8 wherein said first
decurling member is advanceable from a neutral position into
engagement with one surface of such web for controllably producing
change in the path geometrty of such web and said second decurling
member is advanceable from a neutral position into engagement with
the other surface of such web for controllably producing change in
the path geometry of such web.
10. Decurling apparatus according to claim 6 wherein said cam means
comprises a cam surface associated with said means movably mounting
said decurling member and a cooperating cam follower extending from
said means movably mounting said compensating roller means.
Description
BACKGROUND OF INVENTION
In the treatment and processing of fibrous webs, it is advantageous
to employ a device for conditioning the web to control its curl
characteristics. The curl characteristics of the web determine its
aerodynamic properties which, in turn, substantially influence the
ease with which the web is handled. The effect of aerodynamic
properties of the web is especially evident in the handling of web
material at high speeds, particularly after the web has been cut
into short segments. Undesirable curl characteristics tend to cause
such short segments to fly off their intended path as they are
being transported while advantageous aerodynamic properties assist
in causing the web to travel along a desired path and properly come
to rest in a desired place. Undesirable curl characteristics will
also cause segments of the web to be difficult to stack
mechanically due to unwanted impingement of one segment of web with
an outturned edge of another segment.
In many systems which treat webs and with which decurling devices
are used, a preferred location for the decurling device is
immediately adjacent the system along a portion of the web path
length which is actively maintained in a predetermined registry
with operating elements of the system. Under these circumstances,
however, manipulation of the web by the decurling device to modify
its curl characteristics tends to change the registration between
the web and the elements of the system. In many systems, for
example printing systems, this can not be tolerated. Consequently,
decurling devices are usually located away from the system
operating upon the web, along a portion of the web path length
which is not to be maintained in any particular relationship with
elements of the system.
SUMMARY OF THE INVENTIONS
The decurling apparatus of this invention conditions a web to have
a particular curl characteristic without influencing the length of
the web path. The web is drawn over an elongated decurling member
which alters an undesirable curl characteristic of the web by
imparting to the web a curl tendency which corrects the undesirable
curl tendency. The magnitude of the correcting curl tendency
imparted to the web is a function of the sharpness of the angular
turn of the web as it is drawn over the decurling member. The
position of the decurling member is adjustable to vary the
sharpness of the angular turn of the web thereover and thereby
variably control the magnitude of the correcting curl tendency
imparted to the web.
Compensating means is provided to alter web path geometry in
response to movement of the decurling member. This change in web
path geometry compensates for the change in web path geometry
necessarily produced by movement of the decurling member. The
compensation is in a manner which avoids change in web path length
as the position of decurling member is adjusted.
The decurling device of this invention is therefore usable along
the active web path length of a system without influencing the
relationship between the web and the system.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially cut away perspective view illustrating a
preferred embodiment of this invention;
FIG. 2 is a cross-sectional view of the preferred embodiment of
FIG. 1, taken along line 2--2 of FIG. 1;
FIG. 3 is a schematic view showing the apparatus of FIG. 2 in
another position; and
FIG. 4 is a schematic view showing the apparatus of FIG. 2 in still
another position.
DESCRIPTION OF A PREFERRED EMBODIMENT
The illustrated preferred embodiment of this invention will be
described. Referring to FIGS. 1 and 2, the decurling unit 16 for
operating upon a web 12 includes a support means 22 which rests
upon a base 24. The support means mounts an elevator means 32, a
compensating means 38 and a drive means 40. Base 24 rotatably
supports a pair of turn rollers 26 and 28 and also a resilient
drive roller 30 which is mounted adjacent the turn roller 28 to
form a nip through which the web 12 may be drawn. Elevator means 32
supports decurling rollers 34 and 36 and varies the position of the
decurling rollers in response to operation of the drive means 40.
Included within the drive means 40 is a reversible motor 42, a
sprocket 44, a chain 46, a sprocket 48 for rotating a shaft 50 and
a pair of gear boxes 52 each housing a gearing mechanism, not
shown, driven by the shaft 50. The elevator means 32 includes a
pair of threaded shafts 59 extending from cooperative relationship
with the gearing mechanism in each gear box 52 for reciprocally
operating a pair of carriage plates 54. The carriage plates
rotatably support the decurling rollers 34 and 36. The ends of the
decurling rollers are journaled into bearings means 55, one such
bearing means being mounted upon each carriage plate 54. The
diameter of the decurling rollers is small relative to the diameter
of rollers 26, 28 and 30.
The gap between the rollers 34 and 36 is greater than the thickness
of the web 12 so that either the roller 34 may engage one side of
the web or the roller 36 may engage the other side of the web, or
so that the web may pass between the rollers without being engaged
by either of them. Each carriage plate 54 is mounted for axial
movement along a rigid carriage rod 56 which is firmly mounted to
the support means 22. Bushings 58 provide the necessary support for
the carriage plate 54 while permitting movement thereof along the
rigid carriage rod 56. When the reversible motor 42 is driven in
one direction, the drive means 40 will drive the threaded shaft 59,
and thus the carriage plates and the decurling rollers from the
condition illustrated in FIG. 2 wherein neither of the decurling
rollers engages the web 12 to the condition illustrated in FIG. 3
wherein the decurling roller 34 is positioned to operate upon the
web. Conversely, when the reversible motor 42 is driven in the
opposite direction, the drive means 40 will lift the threaded
shafts to lift both the carriage plates 54 and the decurling
rollers 34 and 36 and thereby position decurling roller 36 for
operation upon the web, as illustrated in FIG. 4.
When elevator means 32 advances the decurling rollers from the
position of FIG. 2 toward the position shown in FIG. 3, the web 12
is contacted by the decurling roller 34 and the magnitude of the
wrap of the web around the decurling roller 34 increases as the
decurling rollers approach the position shown in FIG. 3.
Conversely, movement of the decurling rollers from the position of
FIG. 2 toward the position shown in FIG. 4 brings decurling roller
36 into contact with the web 12 and the magnitude of the wrap of
the web 12 around the decurling roller 36 increases as the
decurling rollers approach the position shown in FIG. 4. The amount
of decurling action applied to the web by the decurling rollers
increases as the wrap of the web around the rollers increases. It
will be appreciated that operation upon the web by the decurling
roller 34 produces a tendency to curl in one direction which
compensates for an objectionable tendency of the web to curl in the
opposite direction. Similarly, operation upon the web by the
decurling roller 36 imparts to the web a tendency to curl in the
aforesaid opposite direction to compensate for an objectionable
tendency of the web to curl in the aforesaid one direction.
Variation in the position of the decurling rollers 34 and 36
necessarily effects a change in the geometry of the path of web 12.
The change in web path geometry would produce a change in web path
length between rollers 26 and 28 except for compensation provided
by the compensating means 38. Such alteration of the web path
length produces objectionable loss of registry between the web 12
and apparatus which operates upon the web either before the web
reaches the unit 16 or after it emerges therefrom. The compensating
means 38 responds to relative movement between the web 12 and the
decurling rollers to change web path geometry in a manner which
compensates for the tendency of web path length to vary when the
aforesaid relative movement between the web and decurling rollers
occurs.
The compensating means 38 comprises a pair of cam followers 62
adapted to cooperate with the cams 60 formed in the carriage plates
54. The pair of cam followers 62 extend from a pair of cam follower
shafts 64 mounted for reciprocation along their longitudinal axes
by bearings 66. The cams 60 and cam followers 62 operatively
interconnect the compensating means 38 and the elevator means 32.
Depending from each of the cam follower shafts 64 and keyed thereto
by means 70 is a support 68. Rotatably mounted between the supports
68 is a compensating roller 72 having a diameter larger than the
diameter of the decurling rollers 34 or 36. In response to
reciprocatory movement of the carriage plates 54 the cam follower
shafts 64 reciprocate along their longitudinal axes and thereby
cause the supports 68 and the compensating roller 72 to
reciprocate. As shown in FIG. 2, the web passes over turn roller
26, between decurling rollers 34 and 36, around compensating roller
72 and then through the nip between turn roller 28 and resilient
drive roller 30. As seen in FIG. 2, the apparatus is in a neutral
position wherein the web is not operated upon by the decurler
16.
In the condition illustrated in FIG. 3, the decurling roller 34 is
in position for engaging one surface of the web 12 for imparting to
the web the maximum tendency to curl in one direction. The
condition of FIG. 3 is achieved by driving the elevator means 32 to
its full downward position. In response to this motion of the
elevator means 32, the cam followers 62 and the cam follower shafts
64 are drawn by portion 60' of cams 60 along a path substantially
normal to the path of the elevator means to draw the supports 68
and the compensating roller 72 toward turn roller 26. The change in
web path geometry produced by the compensating roller 72
compensates for that produced by the decurling roller 34.
Therefore, no change in web path length results. In the condition
illustrated by FIG. 4, the other surface of web 12 is engaged by
decurling roller 36 impart to the web 12 the maximum tendency to
curl in the other direction. When decurling roller 36 is selected
for use, the portion 60" of cam 60 controls movement of the
compensating roller 72.
The character of the compensation provided by the motion of the
compensating roller 72 is dependent upon the shape of cams 60.
Accordingly, a discussion will follow setting forth the general
manner in which the shape of the cam 60 in the preferred embodiment
was determined. The general layout of the decurling apparatus was
formulated and sketched. That is, the sizes and relative positions
of all the elements influencing web path geometry and length were
determined. Two reference points were then chosen, one on each side
of the decurling roller, between which the web path length is to be
maintained constant as the decurling roller is moved. For
convenience in computations, the loci of the points should be close
as possible to the decurling roller. In the preferred embodiment,
these points are A and B. Point A is located where web 12
tangentially contacts fixed turn roller 26 and point B is located
at the center of the nip where web 12 passes between fixed turn
roller 28 and resilient drive roller 30. The path of movement of
the decurling rollers was then determined. A path along a line
passing through the longitudinal axes of the decurling rollers
perpendicularly thereof, substantially normal to the undefected
path of the web between rollers 26 and 72, is preferred. Next, the
identity of the roller which is movably mounted to compensate for
movement of the decurling roller and the desired path of its
movement is determined. Roller 72 was selected and movement along a
path perpendicular to the direction of movement of the decurling
rolls was chosen for simplicity.
An algebraic equation for web path length between the selected
reference points A and B was written in terms of web path geometry.
It should be observed that the equation must be solved separately
to determine the cam shape to be associated with each of the
decurling rollers. That is, the shape of the portion 60' of the cam
60 which governs the movement of roller 72 when the decurling
roller 34 is in use and the shape of the portion 60" of the cam 60
which governs the movement of roller 72 when the decurling roller
36 is in use must be independently determined. This independent
determination of the shapes of portions 60' and 60" of the cam 60
is required because the displacement of roller 72 to compensate for
a given downward displacement of the elevator means 32, which
brings decurling roller 34 in contact with the web 12, is not equal
to the displacement of compensating roller 72 to compensate for an
equal upward displacement of the elevator means to bring decurling
roller 36 in contact with the web.
For the apparatus shown in FIGS. 1 and 2, the equation included
terms for the radii of turn roller 26, a selected one of the two
decurling rollers 34 and 36, compensating roller 72 and turn roller
28. Also included in the equation were terms for the spacing
between turn roller 26 and the selected decurling roller, the
spacing between compensating roller 72 and the selected decurling
roller and the spacing between the compensating roller 72 and turn
roller 28. Terms were also included for displacement of the
selected decurling roller and displacement of the compensating
roller 72. A term for the angle defined at the geometric center of
compensating roller 72 by radial lines extending therefrom to the
two points on the roller surface at which web 12 is tangent to the
roller surface was included. A similar term for the angle formed at
the geometric center of the selected decurling roller by radial
lines extending therefrom to points on the surface of the decurling
roller at which the web is tangent to the surface of the decurling
roller was also included. A determination was then made of the
exact web length between the two reference points. This length was
set equal to the algebraic expression.
Numbers were then substituted for all equation terms which are
constant. A number of displacement values for the decurling roller
were then assumed. Utilizing each assumed value, the expression was
solved by a trial and error process to determine corresponding
displacement values for the compensating roller. The displacement
values for the decurling roller were plotted against the
displacement values for the compensating roller to determine the
shape of the portion of the cam 60 which governs the pattern of
movement of the compensating roller 72 when the selected one of the
decurling rollers is in use. In similar manner, the equation was
solved a second series of times and the resulting values were
plotted to determine the shape for the other portion of the cam 60
which governs the pattern of movement of the compensating roller
when the other of the two decurling rollers is in use.
Operation of decurling unit 16 will now be described.
It will first be assumed that, in an initial condition, the web
does not have any objectionable tendency to curl as it enters
decurler 16. In this condition, the decurler is set in a neutral
position, as shown in FIG. 2, wherein it performs no operation upon
the web 12. The web 12 is drawn over the turn roller 26 and between
the decurling rollers and 34 and 36. The decurling rollers are
positioned so that the web passes therebetween without contacting
the surface of either roller. After passing between the decurling
rollers, the web is drawn over compensating roller 72 and through
the nip formed by turn roller 28 and resilient drive roller 30. A
certain length of web is obtained between point A at turn roller 26
and point B at turn roller 28. During operation of the decurling
unit 16, the length of web between points A and B must remain
constant to insure that systems preceeding or following unit 16 are
free from change in the relative positions of the web and elements
of the system.
It will next be assumed that the web begins to pass through the
system with an undesirable tendency to curl upon itself in a
counterclockwise fashion. This tendency is corrected by bringing
decurling roller 34 into contact with the web so as to apply
thereto a tendency to curl in a clockwise fashion. The magnitude of
the clockwise curl tendency must equal the objectionable
counterclockwise curl tendency to achieve full compensation. The
result is a web having the desired curl characteristics. It may be
desirable to provide a web entirely free of curl or it may be
desirable to provide a web having a predetermined curl.
The magnitude of the compensating curl tendency applied to the web
12 by the decurling roller 34 varies in accordance with the amount
of the surface contact between the decurling roller and the web as
the web passes over the roller. The amount of compensating curl
tendency increases as the area of contact between the decurling
roller and the web increases and decreases as the area of contact
between the web and the decurling roller decreases. Stated
differently, the amount of curl tendency imparted to the web by the
decurling roller increases or decreases with increase or decrease,
respectively, in the sharpness of the angular turn in the path of
the web over the decurling roller. Accordingly, as the decurling
roller 34 first contacts the web, a relatively small amount of
compensating curl tendency is applied thereto and as the position
of the decurling roller is continuously changed to increase the
sharpness of the angular turn in the path of the web over the
decurling roller, the compensating curl tendency increases. The
compensating curl tendency is so increased until it relieves the
objectionable curl tendency. Then the web 12 emerges from the
decurling unit having the desired curl characteristics. To advance
decurling roller 34 into contact with the web 12, reversible motor
42 is actuated to cause drive means 40 to drive threaded shafts 59
downwardly, as seen in FIG. 3, so that the decurling roller engages
the web 12 to impart thereto a tendency to curl about itself in a
clockwise direction. The decurling roller 32 is advanced downwardly
until the angular path of the web over the decurling roller
provides a compensating curl tendency of the desired magnitude.
When the web 12 is without objectionable curl, motor 42 is cut off
and the decurling roller 34 remains as then positioned. When
conditions change and a compensating curl tendency of different
magnitude is required, elevator means 32 is again operated to
reposition the decurling rollers. FIG. 3 shows the apparatus of
FIG. 2 set to impart the maximum amount of clockwise compensating
curl tendency to the web 12.
If the web 12 is characterized by an objectionable tendency to curl
upon itself in a clockwise direction, the decurling apparatus 16 is
operated in a manner similar to that described above except
elevator means 32 is raised rather than lowered to bring decurling
roller 36 into engagement with the web 12. The decurling roller 36
applies to the web a tendency to curl upon itself in a
counterclockwise fashion so that it compensates for objectionable
clockwise curl tendency. See FIG. 4.
As the decurling roller 34 or decurling roller 36 moves to change
the path of the web 12, it changes the web path geometry in a
manner which tends to lengthen the overall web path between points
A and B. Actual change in the path length between these two points
is avoided however, by shifting the position of compensating roller
72 in response to motion of elevator means 32. Cams 60, shaped in
the manner described above, cause the cam follower shafts 54 to
move along their longitudinal axes to reposition supports 68 and
compensating roller 72 as the elevator means 32 moves the decurling
rollers with respect to the web 12. Movement of the compensating
roller 72 tends to shorten or lengthen the web path by an amount
equal to the tendency of the decurling roller movement to lengthen
or shorten, respectively, the web path. The overall length of the
web path between points A and B thereby remains constant.
It will now be appreciated that this invention provides apparatus
for decurling a web without influencing the web path length. It is
to be understood, however, that the foregoing description is of a
preferred embodiment and that the invention is not limited to the
specific apparatus shown and described. Therefore, changes may be
made in the described preferred embodiment without departing from
the scope of the invention.
* * * * *