Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to the art of slitting paper webs,
and is more particularly concerned with new and improved means and
methoa which avoids certain problems inherent in prior slitting
techniques.
Heretofore, shearin~ of paper web has generally been by
means of a sharp beveled top rotating blade running in contact with
a relatively lecs sharp bottom band. The angles of the top blade
and bottom band may vary, but the top blade usually runs from 30
to 90 degrees included angle. The bottom band has an approximately
3~ to 10 bevel on the cutting surf~ce. Further, in order to
effectively shear material, it is necessary to toe-in and overlap
the top blade with the bottom band to ensure blade contact at only
one point, which is called the cut point, and is the vnly point of
contact between the two componen-ts.
As thus described, the prior expedients have been plagued
with certain problems which manifes~ themselves not only in the
excessive dust generated, but also in a plow effect of the bevel and
toe-in of the top blade. Such bevel on the top blade is necessary to
reduce the cutting force necessary to shear the paper. Also,a sharp
point has a higher concentration o~ load then a ~lat surface. The
be~el, however, creates a tension in ~he plane of th~ paper to help
sever the fiber. Nevertheless, *he almost inevitable plow effect
causes tearing rather than incising of the web and thus contributes
to the dust problem, in addition to the dust generated due to slitter
blade contact and wear.
Another problem due to slitter wear is that as the blade
wears, it is necessary to resharpen the same, thus reducing its
diameter. This requires re~uent readjus-tments in an attempt to
maintain proper cut point.
A principal aim o~ the present inventi~n is to overcome
the Eoregoiny and other disadvantages, drawbacks, inefficiences,
shortcomings and problems inherent in prior practice, and to effect
substantial improvements in slitting of paper webs.
To this end, it is an important object of the present
invention to provide new and improved means for slitting paper webs,
in which the slitter components do not make con~act with one another.
Another object of the invention is to substantially
ellminate the plow effect during paper web sli~ting.
Another object of the invention is to substantially
eliminate the dust problem during paper web slitting.
~ further object of ~he invention is to provide a new
and improved paper web slitter in which wear of the slitter components
is greatly minimized, and adjustability of components is sl~stantlally
simplified and facilitated.
In an embodiment of the invention, a paper web slitter
has a pair of cooperating circular rotary members which have
periph~ral web slitting edges in non-contacting radial opposition to
one another for engaging therebetween a running paper web ~o be slit,
the space between the points of closest approach of said edges being
sufficiently less than the thickness of the running pape~ web and so
related to the physical properties of said web as to cause compression
severance slitting of said web, and means acting on said members
for maintaining said edge points in compression severance slitting
engagement with said web.
The invention also provides a method of slitting a paper
web, comprising running sai.d web in engagement between non-contacting
radially opposed peripheral web slitting edges of a pair of
cooperating circular r~tary members, and maintaining the space
between the points of closest approach of said edges sufficiently
less than the thickness of said web and 50 related to the physical
properties of said web as to cause compressl.on seYerance slitting
of said web as the web runs in engagemen~ with said edges.
Other objects, features and advantages o the inventi~n
will be readily apparent from the following descripkion of a certain
representative embodiment thereof, ~aken LII c~njunction with the
accompanying drawing although varia~ions and modifica~ions may be
effected without departing from the spirit and scope of the novel
concepts embodied in the disclosure and in which:
Fig. 1 is a schematic side elevational view of a slitter
and winder emb~dying features of the invention;
Fig. ~ is an enlarged fragmental vertical sectional
elevational detail view taken substalltially a.l.ony the line II-II of
Fig. l;
Fig. 3 is a fxagmentary elevational view taken sub.stantially
in the planè of line III-III of ~ig. 2;
Fig. 4 is an enlarged i.llustrative sectional v.iew taken
substantially in the area IV of Fig. 2; and
Fig. 5 is a fragmentary schematic illustrative view
taken substantially along the lin~ V-V of Fig. 4.
By way of example, a slitter 10 ~ig~ 1) embodying the
in~ention is adapted to be supported by a suitable frame 11 -to
receive paper web W fed therethrouyh from any suitable source such
as a paper making machine,calender,or a source roll (no~ shown).
From the ~ource, the paper web W is adapted to pass about a guide
roller 1~ to an~ through the slitter 10, and the slit web leaving
the slit-ter and passirq to a shee~er or any other desired process,
or may be ~uicled about a drum 13 and wound into rolls 14 which may
in addition to support from the dr~n 13, receive support from a
cooperating drum 15. l'he drl~m 13 may be powered in any desirable
manner, represented schematically by the drive means 17.
The slitter 10 may be equipped ko slit the web W into
as many strips to be wound on the individual rolls 14 as deslred,
havi~g re~ard to the kind of paper web being processed. By the
term "paper web" any kind of paper web is intended which is
susceptible ~o being slit by the slitter 10. A characteristic of
a-l paper webs is that they comprise fiber matrix as the principal
material although various treating materlals, fillers and the like
may be carried by or incorporatecl in the web. By the term "web"
is meant either a single layer web or a plurality of individually
formed webs which may pass through the slitter 10 in laminar relation~
as depicted by way of illustration in the drawings, such as facial
or toilet tissue or fine paper for a sheeter~ and which is often
employed in double thickness.
In the slitter 10, the web ~ is slit hetween one or
more pairs of cooperating circular rotary components or mem'oers,
comprising for each slit to ~e made, a top member 18 and a bottom
member 19. As .is generally the case, a plurality of pairs of the
slitter members 18 and 19 is employed across ~he width of the web W,
one pair being adjacent to one longitudinal side edge o the web, and
another pair being adjacent to the opposite side edge of the web
and serving to trim off the side edge portions of the web which may
be discarded. One or more pairs of the slitter members are located
at additional desired intervals across the web determinative of the
width of the strips into which the web is to be slit. Although
each of the rotary slitter members 18 and 1~ may be separately
,
xotatably mounted, all of the upper members 18 may be
mounted corotatively on a common shaft 20 and all of the
lower members 19 may be corotatively mounted on a common
shaft 21. Preferably, both of the shafts 20 and 21 are
driven but for some applications only the lower shaft 21
may be driven at the speed predetermined for the running
speed of the web W. Where both the top and bottom members
18 and 19 are driven, a desirable slicing effect results.
; No particular driving means are shown for the shafts 20
and 21 because such driving means are well known. Supported
journalling of the shaft 21 on the frame 11 is by means of
suitable bearings 22 at opposite ends of the shaft.
Mounting of the upper shaft 20 may be by means
which will permit vertical adjustment o~ the upper slitter
members 18 relative to the companion lower slitter members
19. Such means may comprise respective bearing blocks 23
carrying the opposite ends of the sha~t 20 and vertically
adjustable in respective vertical ways 2~ b~ means such as
respective adjustment screws25 carried by a supporting frame
head 27 and adapted to be locked in adjustment by means of
locking nuts 28. On the other hand, the upper slitter com-
ponents 18 may be individually adjustable. In any event,
the members 18 and 19 and their shafts 20 and 21 should be
supported in a rigid and sturdy manner, to as nearly as
practicable, avoid deflection of the slitter components,
and in particular at the edges 29 and 30.
According to the present invention, each of the
upper slitting members has a pe.riphera~ web slitting edge 29 and
each of the lower slitting members 19 has a pexipheral web slitting
edge 30 and the edges 29 and 30 are in non-contacting radial
opposition to one another for enyaging therebetween the running
pap~r web W to be slit. The space between the points of closest
approach of the edges 29 and 30 must be sufficiently less than
the thickness of the running paper web W and so related to ~he
physical properties of the web as to cause compression severance
slitting of the web.
For maximum resistance to wear, such as may be caused
by abrasiveness in the paper web, the edges 2~ and 30 may be provided
on highly wear resistant material such as carbide rings 31 and 32,
respectively, carried by the bodies of the members 18 and 19
constructed from a less expensive material.
For optimum results, the perimeters of the members 18
and 19 should have only a very shallow angle relative ~o the
cutting edges 29 and 30 of from 0 to ~0. rrhe smaller the angle
the better. Overlap of the non-contacting edges 29 and 30 in
axial direction where, as best seen in Figs. 2 and 4, the edges
29 and 30 are at the adjacent axial faces of the members 18 an~ 19,
should be as little as practicabl~ such as from 0 to .010 inch.
For best results, the radial spacing between the edges 29 and 30
should be no greater than 0-30% of the thickness of the web.
Proper radial spacing and then maintenance OI the edges 29 and 30
in the optimum compression .severance slitting engagement with the
web is adapted to be accomplished by means of the adjustment
screws 25 or individual adjustmen~ of the m~ers 18 and 19.
Supporti~g table means 33 supports the web W in stable
condition, and for this purpose~ the upper supporting surface of
the table means is in ~ proper plane with respect to the edges 29
and 30~ Suitable clearance openings 34 in the table 33 provide
clearance for the lower members 19.
As best visualized in Figs. 4 and 5, as the web runs
through the rotating ~ooperating eircul~r rotary slitter members
18 and 19, the non-contactin~ slitting edges 29 and 30 at the
closest approach or severance point of the edges severely compress
the engaged web and compact the fibers from the web t.hickness,
as indicated between the arrows T (Fig. 5), to the extent indicated
between the arrows S Ishown as about 30~) so that fiber failure
is caused and thus severance of the web along the slit line. By
this method, there is minimum tens.ion in the plane of the web, so
that tearing is precluded. There is practically no plowing effect.
Dust is substantially eliminated or at least greatly minimi~ed.
The to~and bottom slitter members 18 and 19 can be
preadjusted transversely relative to the web to attain the
desired strip widths of the slit web. Adjustment of the radial
spacing at the severance points between the slitting edges 29 and
30 relative to the particular web to be slit, can be readily effected
by adjusting all of the upper members 18 in unison relative to the
lower mem~ers 19. Vertical loading of the slitter me~ers 18 and
19 relative to one another may be on the order of from 200 to 800
pli at said points of closest approach in severance engagement with
the web and depending on the physical character and thickness of
the particular web to be slit.
~ mong numerous advanta~es inherent in the web
slitter and method of slitting according to the present invention
may be mentioned that no side loading of slitter blades is
necessary; no penetration adjustmerrt. of slitter blades is necessary;
there is no wear caused by knife contact; the web or web strips
may be wrapped around the upper or bottom slitter members, if
desired; cross machine adjustmen-~ of the top and bottom slitter
members may be effected while ~he web is in the slitter; there
i5 maximum slitter member life; ~he upper and lower slitter members
need not be adjusted in axial direction even though some
adjustment may be necesaary from time-to-time in the radial
~ direction.
: It will be understQod that variations and modifications
may be effected without departing from the spirit and scope o the
novel concepts of this invention.
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