U.S. patent application number 12/727232 was filed with the patent office on 2010-09-30 for web traveling position regulating method, web manufacturing method, web conveying device and web cutting device.
This patent application is currently assigned to FUJIFILM CORPORATION. Invention is credited to Masatoshi OKU.
Application Number | 20100243788 12/727232 |
Document ID | / |
Family ID | 42782884 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100243788 |
Kind Code |
A1 |
OKU; Masatoshi |
September 30, 2010 |
WEB TRAVELING POSITION REGULATING METHOD, WEB MANUFACTURING METHOD,
WEB CONVEYING DEVICE AND WEB CUTTING DEVICE
Abstract
The present invention provides a web traveling position
regulating method, a web manufacturing method and a web conveying
device that, without relying on a roller whose peripheral surface
is crown-shaped, can carry out transverse direction position
regulation of a web that travels, and provides a web cutting device
to which the web conveying device is applied and that, by a simple
structure, can carry out transverse direction position regulation
of plural webs that travel.
Inventors: |
OKU; Masatoshi; (Kanagawa,
JP) |
Correspondence
Address: |
Solaris Intellectual Property Group, PLLC
401 Holland Lane, Suite 407
Alexandria
VA
22314
US
|
Assignee: |
FUJIFILM CORPORATION
Tokyo
JP
|
Family ID: |
42782884 |
Appl. No.: |
12/727232 |
Filed: |
March 19, 2010 |
Current U.S.
Class: |
242/525 ;
226/188; 226/3; 242/548 |
Current CPC
Class: |
B65H 23/038 20130101;
B65H 2301/4148 20130101; B65H 35/02 20130101; B65H 2404/1313
20130101; B65H 2404/13161 20130101; B65H 2404/1311 20130101; B65H
2701/378 20130101 |
Class at
Publication: |
242/525 ; 226/3;
242/548; 226/188 |
International
Class: |
B65H 23/038 20060101
B65H023/038; B65H 18/08 20060101 B65H018/08; B65H 35/02 20060101
B65H035/02; B65H 20/00 20060101 B65H020/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2009 |
JP |
2009-071563 |
Claims
1. A web traveling position regulating method comprising training a
web around a peripheral surface at a roller, which peripheral
surface forms a concave shape at which an axial direction center
has a smaller diameter than axial direction end portions, and
causing the web to travel while sliding the web with respect to the
roller, thereby regulating a traveling position in a transverse
direction of the web.
2. The web traveling position regulating method of claim 1, wherein
the web is made to travel while being slid with respect to the
roller, by driving and rotating the roller such that a peripheral
speed of the peripheral surface of the roller is faster than a
traveling speed of the web.
3. A web manufacturing method comprising: training a web around a
peripheral surface at a roller, which peripheral surface forms a
concave shape at which an axial direction center has a smaller
diameter than axial direction end portions, causing the web to
travel while sliding the web with respect to the roller, and
regulating a traveling position in a transverse direction of the
web; and taking-up the regulated web coaxially.
4. The web manufacturing method of claim 3, further comprising:
drawing-out a web original sheet; and dividing the web original
sheet in the transverse direction and cutting the web original
sheet into a plurality of webs.
5. The web manufacturing method of claim 3, wherein the web is made
to travel while being slid with respect to the roller, by driving
and rotating the roller such that a peripheral speed of the
peripheral surface of the roller is faster than a traveling speed
of the web.
6. A web conveying device comprising: a web traveling section that
causes a web to travel in a longitudinal direction; a roller
provided at a traveling path of the web by the web traveling
section, and having a concave peripheral surface at which an axial
direction center has a smaller diameter than axial direction end
portions, the web being trained around the peripheral surface; and
roller driving means driving and rotating the roller at a speed at
which sliding of the web with respect to the roller arises.
7. The web conveying device of claim 6, wherein the roller driving
means is structured so as to drive and rotate the roller such that,
at least when a traveling speed of the web is less than a
predetermined speed, a peripheral speed of the peripheral surface
of the roller is faster than the traveling speed of the web.
8. A web cutting device comprising: a draw-out section for
drawing-out a web original sheet; a cutting section that divides
the web original sheet in a transverse direction and cuts the web
original sheet into a plurality of webs; a take-up section for
coaxially taking-up at least two or more webs among the webs that
are formed by cutting at the cutting section; and the web conveying
device of claim 6 that is applied such that, due to the web
traveling section, the web original sheet is drawn-out from the
draw-out section and the webs are taken-up at the take-up section,
wherein the roller that structures the web conveying device is
structured such that a plurality of the concave peripheral
surfaces, at which the at least two or more webs that are to be
taken-up at the take-up section are trained independently, are
disposed in parallel in an axial direction.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 USC 119 from
Japanese Patent Application No. 2009-071563, filed Mar. 24, 2009,
the disclosure of which is incorporated by reference herein.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates a web traveling position
regulating method, a web manufacturing method, a web conveying
device and a web cutting device for a web that is a flexible
elongated body such as, for example, a magnetic tape or the
like.
[0004] 2. Related Art
[0005] There is known a technique that uses a roller whose
peripheral surface is crown-shaped in order to prevent lateral
offset of a tape that is drawn-out from a tape supply source.
[0006] However, in a conventional technique such as that described
above, in order to center the tape by the crown-shaped peripheral
surface, the tape must be gripped at the peripheral surface of the
roller. Thus, there are limitations on the applications of a
conventional technique such as described above, and other methods
and devices that regulate the transverse direction position of a
web that travels are desired.
SUMMARY
[0007] The present invention provides a web traveling position
regulating method, a web manufacturing method and a web conveying
device that, without relying on a roller whose peripheral surface
is crown-shaped, can carry out transverse direction position
regulation of a web that travels, and provides a web cutting device
to which the web conveying device is applied and that, by a simple
structure, can carry out transverse direction position regulation
of plural webs that travel.
[0008] A first aspect relating to the present invention is a web
traveling position regulating method that includes training a web
around a peripheral surface at a roller, which peripheral surface
forms a concave shape at which an axial direction center has a
smaller diameter than axial direction end portions, and causing the
web to travel while sliding the web with respect to the roller,
thereby regulating a traveling position in a transverse direction
of the web.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] An exemplary embodiment of the present invention will be
described in detail based on the following figures, wherein:
[0010] FIG. 1 is a side view showing the schematic overall
structure of a centering roller that structures a magnetic tape
manufacturing device relating to an exemplary embodiment of the
present invention;
[0011] FIG. 2 is a side view schematically showing, in an enlarged
manner, a portion of the centering roller that structures the
magnetic tape manufacturing device relating to the exemplary
embodiment of the present invention;
[0012] FIG. 3 is a side view schematically showing the schematic
overall structure of the magnetic tape manufacturing device
relating to the exemplary embodiment of the present invention;
[0013] FIG. 4 is a plan view schematically showing a slitter that
structures the magnetic tape manufacturing device relating to the
exemplary embodiment of the present invention;
[0014] FIG. 5 is a graph that shows, in comparison with comparative
examples, results of centering by the centering roller that
structures the magnetic tape manufacturing device relating to the
exemplary embodiment of the present invention;
[0015] FIG. 6 is a side view schematically showing the schematic
structure of a testing device for measuring the results of
centering of FIG. 5;
[0016] FIG. 7A is a graph showing tension fluctuations of a
magnetic tape in the magnetic tape manufacturing device relating to
the exemplary embodiment of the present invention;
[0017] FIG. 7B is a graph showing tension fluctuations of a
magnetic tape in a magnetic tape manufacturing device relating to a
comparative example;
[0018] FIG. 8 is a drawing for explaining the effects of centering
by the centering roller relating to the exemplary embodiment of the
present invention, and is a graph showing the relationships between
tension at a side before or at a side after the roller in a
stationary state of the tape, and the roller peripheral speed;
[0019] FIG. 9 is a drawing for explaining the effects of centering
by the centering roller relating to the exemplary embodiment of the
present invention, and is a graph showing the relationship between
a tape floating amount with respect to the roller in a stationary
state of the tape, and the roller peripheral speed;
[0020] FIG. 10 is a drawing for explaining the effects of centering
by the centering roller relating to the exemplary embodiment of the
present invention, and is a graph showing the relationship between
the standard deviation of relative displacement in the transverse
direction of a tape with respect to the roller in a stationary
state of the tape, and the roller peripheral speed; and
[0021] FIG. 11 is a schematic drawing of a testing device for
obtaining the graphs of FIG. 8 through FIG. 10.
DETAILED DESCRIPTION
[0022] A magnetic tape manufacturing device 10, that serves as a
web cutting device to which are applied a web traveling position
regulating method, a web manufacturing method, a web conveying
device and a web conveying device relating to an exemplary
embodiment of the present invention, will be described on the basis
of FIG. 1 through FIG. 7A and FIG. 7B. First, the schematic overall
structure of the magnetic tape manufacturing device 10 will be
described. Then, a centering roller 38, which is a main portion of
the present invention, will be described in detail.
[0023] (Magnetic Tape Manufacturing Device)
[0024] A portion of the magnetic tape manufacturing device 10 is
shown in a schematic side view in FIG. 3. As shown in FIG. 3, the
magnetic tape manufacturing device 10 is a device that manufactures
a high-density magnetic recording tape 11 (hereinafter simply
called "magnetic tape 11") that serves as a web for, for example,
computer back-up. The magnetic tape manufacturing device 10
manufactures the plural narrow-width magnetic tapes 11 by cutting a
magnetic tape original sheet 12, that has a wide width and serves
as the web original sheet in the present invention, along the
longitudinal direction.
[0025] Concretely, the magnetic tape original sheet 12 is formed in
the shape of a strip having a wider width than that of the magnetic
tape 11 that is the manufactured product. For example, the magnetic
tape original sheet 12 is manufactured by forming a magnetic layer,
that includes strong magnetic particulates, on a non-magnetic
substrate by coating or vacuum deposition or the like, and carrying
out orienting processing, drying processing, surface treatment, and
the like on the magnetic layer. The magnetic tape original sheet 12
is wound in the form of a roll on a hub 14 that serves as a winding
core, and forms a magnetic tape original sheet roll 16 that serves
as a roll-shaped original sheet. The magnetic tape original sheet
roll 16 is supported so as to rotate freely around the axis via the
hub 14, and structures a draw-out section (also called unwinding
section) 15. Due thereto, at the magnetic tape manufacturing device
10, continuous unwinding of the magnetic tape original sheet 12
from the magnetic tape original sheet roll 16 is possible.
[0026] The magnetic tape original sheet 12 is trained around a feed
roller 18 that serves as a web traveling portion and is also a
reference roller. By driving the feed roller 18, the magnetic tape
original sheet 12 is continuously unwound and fed-out from the
magnetic tape original sheet roll 16. A slitter 20, that serves as
a cutting portion for cutting the magnetic tape original sheet 12
along the longitudinal direction at plural places thereof in the
transverse direction, is disposed at the downstream side of the
feed roller 18.
[0027] As shown in FIG. 4 as well, the slitter 20 has plural pairs
of rotating upper blades 22 and rotating lower blades 24 that are
paired upward and downward and that are parallel in the transverse
direction of the magnetic tape original sheet 12. The respective
rotating upper blades 22 are driven and rotated by a motor 26, and
the respective rotating lower blades 24 are driven and rotated by a
motor 28.
[0028] The magnetic tape original sheet 12, that is fed-in between
the plural pairs of rotating upper blades 22 and rotating lower
blades 24 that structure the slitter 20, is divided uniformly in
the tape transverse direction such that the plural, narrow-width
magnetic tapes 11 are formed. In the present exemplary embodiment,
a width Wt (see FIG. 2) of the magnetic tape 11 is approximately
12.65 [mm].
[0029] Returning to FIG. 3, the magnetic tapes 11 after being cut
by the slitter 20 are trained around path rollers 30, and
thereafter, are taken-up onto take-up hubs 32 that rotate
synchronously with the feed roller 18, such that so-called pancakes
24 are formed. A plurality of each of the path roller 30 and the
take-up hub 32 (two of each in the present exemplary embodiment)
are provided. The two path rollers 30 and the two take-up hubs 32
are disposed so as to be offset vertically with respect to one
another in the transverse direction of the magnetic tape original
sheet 12. The magnetic tapes 11 that are adjacent to one another in
the tape transverse direction are offset from one another
vertically, and are taken-up onto the take-up hubs 32. In other
words, in the magnetic tape manufacturing device 10, downstream of
the slitter 20, the traveling path of the magnetic tapes 11
branches off into an upper traveling path Wu and a lower traveling
path W1.
[0030] Further, guide rollers 36, around which the magnetic tape
original sheet 12 or the magnetic tapes 11 are trained, are
appropriately disposed between the magnetic tape original sheet
roll 16 and the feed roller 18, and between the feed roller 18 and
the slitter 20, and between the slitter 20 and the upper and lower
path rollers 30. The centering rollers 38 are respectively disposed
between the guide rollers 36, that are furthest toward the path
rollers 30 side, and the respective upper and lower path rollers
30. Due to each of the centering rollers 38 having a training
surface 40 as will be described later, the centering rollers 38
carry out position regulation in the tape transverse direction of
the magnetic tapes 11 that travel.
[0031] The magnetic tapes 11 that are wound onto the take-up hubs
32 are conveyed as the pancakes 34 to an unillustrated servo
writing device. Servo signals are written to the magnetic tapes
while the magnetic tapes 11 are unwound from the take-up hubs 32 in
a servo process at the servo writing device. Thereafter, the
magnetic tapes 11 are wound onto product reels.
[0032] (Structure of Centering Roller)
[0033] The centering roller 38, that serves as the roller in the
present invention, is a roller for regulating the traveling
position in the tape transverse direction of the magnetic tape 11.
Due thereto, the centering roller 38 exhibits a function of
centering the magnetic tape 11 in the tape transverse direction
with respect to the corresponding take-up hub 32.
[0034] As shown in FIG. 1, the centering roller 38 has a roller
portion 42, at which are formed the plural (40 in the present
exemplary embodiment) training surfaces 40 around which are trained
the magnetic tapes 11 that travel along the upper traveling path Wu
or the lower traveling path W1, and a supporting shaft portion 44
provided at the axially central portion of the roller portion 42.
In the present exemplary embodiment, the centering roller 38 is
structured integrally (manufactured as a single product) such that
the roller portion 42 (the respective training surfaces 40) rotates
coaxially and integrally with the supporting shaft portion 44.
[0035] The respective training surfaces 40 of the centering roller
38, that structures the magnetic tape manufacturing device 10, are
formed in concave shapes at which the respective central portions
in the axial (tape width) direction thereof are recessed toward the
rotational center side as compared with the both end portions.
Accordingly, the centering roller 38 can be understood as being a
so-called concave roller (a structure at which plural concave
rollers are connected in the axial direction). In the present
exemplary embodiment, viewed from a direction orthogonal to the
axis of the centering roller 38, the respective training surfaces
40 form curves (circular arcs in the present exemplary embodiment)
that do not have inflection points.
[0036] More specifically, as shown in FIG. 2, at each of the
training surfaces 40, given that a radial difference between a
minimum radius Rmin (.apprxeq.40 mm) and a maximum radius Rmax is
.DELTA.R, then .DELTA.R=0.2 mm. Further, a width Wr of each
training surface 40 in the axial direction is approximately 25.3 mm
that is twice the width Wt of the magnetic tape 11. As mentioned
above, because each training surface 40 forms a circular arc when
viewed from a direction orthogonal to the axis of the centering
roller 38, it can be understood that a radius of curvature r of
this circular arc is approximately 400 mm, from the above .DELTA.R
and width Wr.
[0037] Further, as shown in FIG. 2, when the magnetic tape 11 is
trained around the training surface 40 such that the tape
transverse direction center line is made to coincide, a radial
difference .DELTA.Rr between the minimum radius Rmin and a trained
maximum radius Rr in the trained range of that magnetic tape 11 is
approximately 0.050 mm. In the present exemplary embodiment, the
respective magnetic tapes 11 are trained over a range of
approximately 90.degree. on the corresponding training surfaces 40
at the centering roller 38 (see FIG. 3). Therefore, a trained
peripheral length difference .DELTA.Lr between the tape transverse
direction central portion and both end portions of the magnetic
tape 11 is approximately 0.078 mm. Moreover, a peripheral length
change rate .DELTA.Lrn, that is computed by dividing the peripheral
length difference .DELTA.Lr by the width Wt of the magnetic tape 11
and non-dimensionalizing, is approximately 0.006. The relationship
between the depth of each training surface 40 and the magnetic tape
11 is expressed (generalized) by this peripheral length change rate
.DELTA.Lrn.
[0038] At each of the training surfaces 40, the indentations and
protrusions are set to be extremely small, in order for slipping
between the training surface 40 and the magnetic tape 11 traveling
thereon to arise easily (in order for the coefficient of friction
to be sufficiently small). Specifically, a surface roughness Ry of
each of the training surfaces 40 is made to be less than or equal
to 0.1 .mu.m. In the present exemplary embodiment, the above
surface roughness of the training surface 40 is set by coating
diamond like carbon (hereinafter called "DLC") on the surface of
the roller portion 42. In the present exemplary embodiment, the
surface roughness Ry of each of the training surfaces 40 is from
0.05 .mu.m to 0.1 .mu.m. Note that the surface roughness Ry of the
magnetic tape 11 trained on the training surface 40 is made to be
sufficiently smaller than 0.1 .mu.m.
[0039] As shown in FIG. 1 and FIG. 3, the centering roller 38
structuring the magnetic tape manufacturing device 10 is driven and
rotated around the axis of the supporting shaft portion 44 by a
roller driving mechanism 46 serving as a roller driving means. The
roller driving mechanism 46 is structured to include at least a
variable speed motor.
[0040] In the magnetic tape manufacturing device 10, at the roller
driving mechanism 46, the rotating speed of the motor is controlled
by the controller 48 such that a peripheral speed Vr at (the
portion of the minimum radius Rmin of) the training surface 40 is
always greater than or equal to a predetermined speed Vs (200 m/min
in the present exemplary embodiment). Specifically, at the roller
driving mechanism 46, the rotating speed of the motor is controlled
by the controller 48 such that, if a traveling speed Vt of the
magnetic tape 11 that is made to travel due to rotation of the feed
roller 18 is lower than the predetermined speed Vs (including cases
in which the tape is stopped), the peripheral speed Vr is made to
substantially coincide with the predetermined speed Vs, and, if the
traveling speed Vt of the magnetic tape 11 is greater than or equal
to the predetermined speed Vs, the peripheral speed Vr is made to
substantially coincide with the traveling speed Vt of the magnetic
tape 11. The predetermined speed Vs is set as a speed at which,
even when the magnetic tape 11 is stopped, air is pulled-in between
that magnetic tape 11 and the training surface 40 (hereinafter this
air is called "accompanying air"), and that magnetic tape 11 and
the training surface 40 do not contact at least at the transverse
direction central portion (details will be described later). Note
that the controller 48 obtains the traveling speed Vt from, for
example, the rotating speed of the feed roller 18 that feeds the
magnetic tape 11 without sliding.
[0041] Due to the above, in the magnetic tape manufacturing device
10, regardless of the traveling speed of the magnetic tape 11, the
magnetic tape 11 travels while sliding substantially completely (in
a non-contact state at least at the transverse direction central
portion) with respect to the training surface 40 of the centering
roller 38. Due thereto, the magnetic tape manufacturing device 10
is structured such that the position of the magnetic tape 11 is
regulated (the magnetic tape 11 is centered) at the axial (tape
transverse) direction central portion of the training surface 40.
The mechanism of this centering will be described hereinafter
together with the operation of the present exemplary
embodiment.
[0042] Operation of the present exemplary embodiment will be
described next.
[0043] In the magnetic tape manufacturing device 10 of the
above-described structure, at the time of manufacturing the plural
magnetic tapes 11 from the magnetic tape original sheet 12, the
feed roller 18 is activated, and the magnetic tape original sheet
12, that is unwound from the magnetic tape original sheet roll 16
of the draw-out section 15, is led to the slitter 20. At the
slitter 20, the magnetic tape original sheet 12 is divided
uniformly in the transverse direction, such that the magnetic tapes
11 are formed. The traveling paths of the plural (80) magnetic
tapes 11 are divided into the upper traveling path Wu and the lower
traveling path W1 alternately in the tape transverse direction, and
the magnetic tapes 11 pass along the guide rollers 36, the
centering rollers 38, and the path rollers 30 that form the
respective traveling paths, and are taken-up onto the take-up hubs
32. The plural pancakes 34 of the predetermined width Wt are
thereby obtained from the wide-width magnetic tape original sheet
12.
[0044] At the time of manufacturing the magnetic tapes 11, the
respective centering rollers 38 are driven and rotated by the
respective roller driving mechanisms 46 such that, from before the
start of traveling of the magnetic tapes 11 due to the feed roller
18, the peripheral speeds Vr coincide with the predetermined speed
Vs. Due thereto, the accompanying air exists between the training
surfaces 40 and the portions of the magnetic tapes 11 which
portions are trained on the training surfaces 40, and, from
immediately after the start of traveling, the magnetic tapes 11
travel while sliding (slipping) substantially completely (in a
non-contact state at least at the transverse direction central
portion) with respect to the training surfaces 40 on which the
magnetic tapes 11 are trained. Further, if the traveling speed Vt
of the magnetic tapes 11 is increased and becomes greater than or
equal to the predetermined speed Vs, the respective centering
rollers 38 are driven and rotated by the respective roller driving
mechanisms 46 such that the peripheral speeds Vr coincide with
traveling speed Vt of the magnetic tapes 11. For these reasons,
accompanying air always exists between the magnetic tapes 11 and
the training surfaces 40. Further, the surface roughnesses of the
magnetic tapes 11 and the training surfaces 40 are made to be less
than or equal to 0.1 .mu.m. Therefore, the thickness of the
accompanying air layer as compared with the indentations and
protrusions of these surfaces is relatively large, and friction
between the magnetic tapes 11 and the training surfaces 40 is
reduced. The magnetic tapes 11 thereby travel while sliding
substantially completely with respect to the training surfaces 40
as described above.
[0045] Due thereto, in the magnetic tape manufacturing device 10,
the position of the magnetic tape 11 is regulated (the magnetic
tape 11 is centered) at the axial direction center of the
corresponding training surface 40, and meandering and swaying that
accompany the traveling are suppressed. This point will be
explained further on the basis of the experimental results that are
shown in FIG. 5. The experimental results shown in FIG. 5 are
results obtained by using a testing device 70 shown in FIG. 6. The
testing device 70 is structured by a tape push-in portion 72 being
provided at a position of a distance L2 (=450 mm) from the
centering roller 38, between the guide roller 36, that is disposed
apart by distance L1 (=750 mm) from the centering roller 38, and
the centering roller 38 (or any of the modified example rollers or
comparative example rollers that will be described later). The tape
push-in portion 72 imparts forced displacement (pushes-in by a
predetermined amount) in the tape transverse direction to the
magnetic tape 11 that is traveling at that position. FIG. 5 shows
the results of measurement of traveling position (offset amount in
the tape transverse direction with respect to the tape transverse
direction center) X1 of the magnetic tape 11 on the centering
roller 38 (or any of the modified example rollers or comparative
example rollers that will be described later), when forced
displacement amount X0 in the transverse direction, that is applied
to the magnetic tape 11 by the tape push-in portion 72, is
imparted. Note that a first comparative example roller is a crown
roller whose training surface is formed in a crown shape and that
is generally used in centering applications. This is a structure in
which, due to a groove, through which the accompanying air escapes,
being formed in the training surface, the magnetic tape 11 is
trained without sliding (the peripheral speed at the maximum
diameter portion coincides with the traveling speed Vt of the
magnetic tape 11). A second comparative example is a flat roller
whose training surface is a cylindrical surface. Due to a groove,
through which the accompanying air escapes, being formed in the
training surface, the magnetic tape 11 is trained without
sliding.
[0046] From FIG. 5, it can be understood that, with the second
comparative example roller, when the forced displacement X0=10 mm
is applied, the offset amount X1 is 5 mm, and the centering effect
due to friction between the roller and the magnetic tape is hardly
exhibited at all. Further, it can be understood that, in the first
comparative example, when the forced displacement X0=10 mm is
applied, the offset amount X1 is 0.5 mm, and when the forced
displacement X0=20 mm is applied, the offset amount X1 is 2 mm, and
a predetermined centering effect is obtained. On the other hand, in
the present exemplary embodiment in which the magnetic tape 11
slides on the training surface 40 of the centering roller 38, when
the forced displacement X0=10 mm is applied, the offset amount X1
is 0 mm, and when the forced displacement X0=20 mm is applied, the
offset amount X1 is 1.5 mm, and it is confirmed that a centering
effect is obtained when either of a small displacement or a large
displacement is imparted. Further, it is confirmed that the
centering roller 38 has a good centering function as compared with
the crown roller relating to the first comparative example, when
either of a small displacement or a large displacement is
imparted.
[0047] Here, the mechanism of the centering operation by the
centering roller 38 will be described further. It is known that the
above-described crown roller exhibits a centering effect on the
magnetic tape 11. This utilizes the property that, when the
magnetic tape 11 is rotated integrally while gripping the surface
of the crown roller by friction, the magnetic tape 11 attempts to
approach the tape transverse direction central portion where the
peripheral speed is the fastest. In contrast, it is assumed that,
when the magnetic tape 11 slips at the training surface 40, the
property that the magnetic tape 11 tends toward the portion where
the peripheral speed is fast is not exhibited, and the magnetic
tape 11 attempts to travel along the shortest path due to tension,
and therefore, the position of the magnetic tape 11 is regulated at
the tape transverse direction central portion that is the minimum
diameter portion at the training surface 40.
[0048] Here, in the magnetic tape manufacturing device 10, because
the magnetic tapes 11 slip at the respective training surfaces 40,
differences in lengths of the magnetic tapes 11 that are conveyed
in parallel are not problematic. For example, in a structure using
crown rollers that the magnetic tapes 11 grip as described above,
in order to absorb the difference in the lengths (traveling speeds
Vt) of the plural magnetic tapes 11 that are parallel, the plural
crown rollers are provided so as to rotate freely with respect to
the supporting shaft portion 44 via bearings respectively. Namely,
a complex structure in which the plural crown rollers, that are
parallel in the axial direction, are provided via bearings so as to
be able to rotate independently, is required.
[0049] In contrast, in the magnetic tape manufacturing device 10,
as described above, the magnetic tapes 11 slip at the respective
training surfaces 40. Therefore, the magnetic tapes 11 of different
lengths can be made to travel (conveyed) at independent traveling
speeds Vt, while the magnetic tape 11 centering function is
exhibited by a simple structure in which the respective training
surfaces 40 rotate integrally (in the present exemplary embodiment,
the single product in which the roller portion 42 and the
supporting shaft portion 44 are formed integrally).
[0050] Moreover, in the magnetic tape manufacturing device 10, the
accuracy of the training surfaces 40 is high (the eccentric amounts
are small) because bearings do not exist between the roller portion
42 and the supporting shaft portion 44. Therefore, in the magnetic
tape manufacturing device 10, rotation deviation of the centering
roller 38, and fluctuations in tension of the magnetic tapes 11
caused by such rotation deviation, are markedly suppressed as
compared with the comparative example that uses that aforementioned
bearings. Specifically, FIG. 7A illustrates measurement of the
relationship (tension fluctuations) between tension and the
longitudinal position of the magnetic tape 11 between the centering
roller 38 and the path roller 30 at a tension fluctuation measuring
section 50 shown in FIG. 3. It can be understood that the tension
fluctuations are markedly suppressed as compared with the tension
fluctuations of the comparative example that are shown in FIG. 7B.
Note that the longitudinal position of the magnetic tape 11 can be
read as time, if the traveling speed Vt is constant.
[0051] In this way, the magnetic tape manufacturing device 10
employs the simple structure of the magnetic tapes 11 slipping at
the respective training surfaces 40. Therefore, the accuracy of the
training surfaces 40 with respect to the rotational center is high,
and a high deviation accuracy can be realized easily. Due thereto,
in the magnetic tape manufacturing device 10, tension fluctuations
of the magnetic tape 11, and adverse affects on tape quality due
thereto, can be effectively suppressed.
[0052] Further, in the magnetic tape manufacturing device 10, if
the traveling speed Vt of the magnetic tape 11 is lower than the
predetermined speed Vs, the controller 48 drives and rotates the
centering roller 38 so that the peripheral speed Vr of the training
surface 40 is made to substantially coincide with the predetermined
speed Vs. Therefore, from the start to the stoppage of operation of
the magnetic tape manufacturing device 10, the state in which the
magnetic tapes 11 is slid substantially completely with respect to
the training surfaces 40 of the centering rollers 38 is
substantially always maintained, and the centering function can be
exhibited. This point will be described with reference to FIG. 8
through FIG. 11.
[0053] FIG. 8 through FIG. 10 illustrate results of testing by a
testing device 80 shown in FIG. 11. The testing device 80 of FIG.
11 rotates the centering roller 38 in a stationary state of the
magnetic tape 11, whose one end is fixed and whose intermediate
portion is trained on the training surface 40 (.DELTA.R=0.2 mm) of
the centering roller 38 and to whose other end a predetermined
tension T0 (.apprxeq.0.98 N) is applied, and measures the tension
of the magnetic tape 11 at the side before and at the side after
the centering roller 38 by tension detectors 82, 84, and measures
the floating amount of the magnetic tape 11 with respect to the
training surface 40 by a floating amount detector (distance sensor)
86. Further, the testing device 80 measures a meandering amount of
the magnetic tape 11 with respect to the training surface 40 by a
meandering amount measuring device 88. FIG. 8 shows the
relationship between the peripheral speed Vr of the training
surface 40 and the tension of the magnetic tape 11 (a value that is
non-dimensionalized by the aforementioned predetermined tension).
FIG. 9 shows the relationship between the peripheral speed Vr of
the training surface 40 and the floating amount of the magnetic
tape 11 with respect to the training surface 40. FIG. 10 shows the
relationship between the peripheral speed Vr of the training
surface 40 and the standard deviation of the relative displacement
in the tape transverse direction of the magnetic tape 11 with
respect to the training surface 40 (the deviation with respect to
an average meandering amount that is obtained by averaging the
meandering amounts at respective peripheral speeds).
[0054] From FIG. 8, it can be understood that tension T1 at the
side before the centering roller 38 decreases as the peripheral
speed Vr increases, and, when the peripheral speed Vr is greater
than or equal to 200 m/min (.apprxeq.Vs), the difference between
the tension T1 and tension T2 at the side after the centering
roller 38 becomes substantially constant. Namely, it can be
understood that, when the peripheral speed Vr is 200 m/min, the
effects of the friction between the magnetic tape 11 and the
training surface 40 (the dragging torque) on the tension T1
decrease, i.e., the magnetic tape 11 is substantially completely
sliding with respect to the training surface 40. Note that the
slight difference between the tensions T1, T2 is thought to be the
effects of friction due to the magnetic tape 11 contacting the
training surface 40 at the transverse direction end portions.
Further, from FIG. 9, it can be understood that the floating amount
of the magnetic tape 11 with respect to the training surface 40,
i.e., the thickness of the accompanying air layer, increases as the
peripheral speed Vr increases, and, in particular, when the
peripheral speed Vr is greater than or equal to 200 m/min
(.apprxeq.Vs), the floating amount exceeds 10 .mu.m. It is assumed
that, in this state, the magnetic tape 11 slides completely
(without contact) with respect to the training surface 40 at least
at the transverse direction central portion. Further, it can be
understood from FIG. 10 that, when the peripheral speed Vr is
greater than or equal to 200 m/min (.apprxeq.Vs), the meandering
amount of the magnetic tape 11 with respect to the training surface
40 is kept small.
[0055] In this way, by setting, as the predetermined speed Vs, the
peripheral speed Vr at which the tension T1 at the side before the
centering roller 38 converges to a predetermined value (the
peripheral speed Vr that does not cause effects on the dragging
torque due to the training surface 40) as shown in FIG. 8, the
magnetic tape 11 can be set in a state of being made to slide
substantially completely with respect to the training surface 40
regardless of the traveling speed Vt of the magnetic tape 11 as
described above, and, even during the time from the activation of
the magnetic tape manufacturing device 10 until a steady operating
state is reached, the function of centering the magnetic tapes 11
well can be exhibited. In other words, by obtaining data as in FIG.
8, the appropriate predetermined speed Vs can be set in accordance
with the dimensions, shapes, surface roughnesses, materials, and
the like of the training surfaces 40 and the magnetic tapes 11.
Further, it can be understood that this is substantiated by the
data of FIG. 9 and FIG. 10.
[0056] Note that the accompanying air, that is pulled-in between
the magnetic tape 11 and the training surface 40, increases
proportionally to the peripheral speed Vr of the training surface
40, and increases proportionally to the traveling speed Vt of the
magnetic tape 11. Therefore, on the whole, the accompanying air
increases proportionally to the sum of the peripheral speed Vr and
the traveling speed Vt of the magnetic tape 11. Thus, after the
traveling speed Vt of the magnetic tape 11 reaches a uniform speed
(in the present exemplary embodiment, the aforementioned
predetermined speed Vs), if the peripheral speed Vr is made to be
the same as the traveling speed Vt of the magnetic tape 11, even if
a speed difference is not set therebetween, sufficient accompanying
air is pulled-in between the magnetic tape 11 and the training
surface 40, and the magnetic tape 11 can be maintained in a state
of being made to slide substantially completely (without contact)
with respect to the training surface 40.
[0057] To summarize the above, in the position regulating method of
the magnetic tape 11 that uses the centering roller 38, and in the
magnetic tape manufacturing device 10 to which this method is
applied, a good centering effect of the magnetic tape 11 can be
obtained even as compared with a crown roller. Further, in the
position regulating method of the magnetic tape 11 that uses the
centering roller 38, and in a tape conveying device to which this
method is applied, with a simple structure in which bearings are
not provided respectively between the supporting shaft portion 44
and the respective training surfaces 40, the lengths of the
respective magnetic tapes 11 can be absorbed, and the method and
device can be applied appropriately to the magnetic tape
manufacturing device 10 that causes the plural magnetic tapes 11
having different lengths to travel in parallel. Moreover, in the
position regulating method of the magnetic tape 11 that uses the
centering roller 38 and in a tape conveying device to which this
method is applied and in the magnetic tape manufacturing device 10
to which these are applied, high accuracy is obtained easily and
rotational deviation is effectively suppressed by making the
centering roller 38 be a simple structure as described above.
[0058] Note that the above-described exemplary embodiment
illustrates an example in which the radial difference .DELTA.R,
that corresponds to the depth (concave amount) of the training
surface 40 that is a concave surface, is 0.2 mm. However, the
present invention is not limited to the same. It is confirmed that,
in respective structures (modified examples) in which at least
.DELTA.R is 0.2 mm, 0.5 mm, 1.0 mm, 2.0 mm, centering effects that
are equivalent to or better than those of the above-described
exemplary embodiment are obtained as shown in FIG. 5. The radius of
curvature r, the radial difference .DELTA.Rr, the peripheral length
difference .DELTA.Lr, and the peripheral length change rate
.DELTA.Lrn of the arc of the training surface 40 in the respective
modified examples are shown in Table 1.
TABLE-US-00001 TABLE 1 .DELTA.R r .DELTA.Rr .DELTA.Lr [mm] [mm]
[mm] [mm] .DELTA.Lrn exemplary embodiment 0.2 400 0.050 0.078 0.006
first modified example 0.5 160 0.125 0.196 0.016 second modified
example 1.0 81 0.247 0.388 0.031 third modified example 2.0 44
0.457 0.718 0.057
[0059] The centering effects in the respective modified examples
are equivalent to or better than those of the above-described
exemplary embodiment, as shown in FIG. 5. Accordingly, it is
confirmed that the centering effect of the training surface 40 of
the centering roller 38 in the present invention is obtained when
the peripheral length difference .DELTA.Lr of the portion on which
the magnetic tape 11 of the predetermined width Wt is trained is
greater than or equal to 0.078 mm, and more generally, when the
peripheral change rate .DELTA.Lrn in the tape transverse direction
of the magnetic tape 11 is greater than or equal to 0.006. Note
that it is confirmed that, if the radial difference .DELTA.R, i.e.,
the peripheral length difference .DELTA.Lr, the peripheral length
change rate .DELTA.Lrn, is great, it becomes easy for wrinkles to
form in the magnetic tape 11 that travels. Even when .DELTA.R is
greater than or equal to 0.5 as shown in FIG. 5, differences do not
arise in the centering effect (the centering effects of the first
through third modified examples are equivalent). Taking these
results into consideration, it is desirable that
.DELTA.R.ltoreq.1.0. In other words, 0.2.ltoreq..DELTA.R.ltoreq.1.0
is desirable, and 0.2.ltoreq..DELTA.R.ltoreq.0.5 is even more
desirable.
[0060] Further, the above exemplary embodiment describes an example
in which the position regulating method of the magnetic tape 11
that uses the centering roller 38 and the tape conveying device to
which this method is applied are applied to the magnetic tape
manufacturing device 10. However, the present invention is not
limited to the same, and can be applied to various types of web
conveying devices. Accordingly, for example, the present invention
may be applied to a take-up device that takes-up a single magnetic
tape 11 onto a product reel such as a tape cassette or the like.
Or, for example, the present invention may be applied to a
conveying device of a web other than a magnetic tape.
[0061] The above exemplary embodiment describes an example in which
control is effected such that, when the traveling speed Vt of the
magnetic tape 11 is less than the predetermined speed Vs, the
peripheral speed Vr coincides with the predetermined speed Vs, and,
when the traveling speed Vt of the magnetic tape 11 is greater than
or equal to the predetermined speed Vs, the peripheral speed Vr
coincides with the traveling speed Vt of the magnetic tape 11.
However, the present invention is not limited to the same. For
example, when the present invention is applied to a device in which
the traveling speed Vt of the magnetic tape 11 is always lower than
the predetermined speed Vs, it suffices that the centering roller
38 be rotated at a uniform speed at which the peripheral speed Vr
substantially coincides with the predetermined speed Vs.
[0062] Moreover, although the above exemplary embodiment describes
an example in which the surface roughness Ry of the training
surface 40 is less than or equal to 0.1 .mu.m, the present
invention is not limited to the same. For example, the peripheral
speed Vr and the surface roughness Ry of the training surface 40
may be appropriately set in accordance with the web that travels.
Further, the present invention is not limited to a structure in
which the training surface 40 is smoothed (is made to be low
friction) by DLC coating, and the training surface 40 can be
smoothed by any of various types of surface treatments or
mechanical workings.
[0063] As described above, in the above exemplary embodiment, the
web is made to travel while sliding is caused between the web and
the roller peripheral surface. Therefore, the web is led to the
central portion in the axial direction of the roller (the
transverse direction of the web), and its transverse direction
position is regulated. The mechanism thereof is thought to be that
the web, that is not guided by friction by sliding to a
large-diameter portion at which the peripheral speed is great, is
led by tension to the central portion in the axial direction of the
roller that is the shortest path.
[0064] Accordingly, positional regulation in the transverse
direction of a web that travels can be carried out without relying
on a roller whose peripheral surface is crown-shaped.
[0065] By forcibly rotating the roller, the web that is traveling
is stably slid with respect to the peripheral surface of the
roller, and regulation of the transverse direction position of the
web that travels can be carried out even better. Namely, at least
when the traveling speed of the web is less than a predetermined
speed, by making the roller peripheral speed be faster than the
traveling speed of the web, the peripheral surface of the roller
and the web can be slid reliably (stably as compared with cases in
which the roller peripheral speed is slower than the web traveling
speed and cases in which the roller peripheral speed is the same
speed as the web traveling speed that is less than the
predetermined speed). Therefore, regulation of the transverse
direction position of the web that travels can be carried out even
better. The control of the present web conveying device is
effective particularly when the traveling speed of the web is low
(including transient states such as during acceleration or the
like). Note that the aforementioned predetermined speed can be set
as the speed of (a vicinity of) the lower limit at which sliding
arises between the web and the roller, even if the web traveling
speed and the roller peripheral speed are the same.
* * * * *