6023P087CA
A DEVICE FOR SEPARATING PAPER SECTIONS FROM A PAPER WEB
WOUND ONTO A PAPER ROLL, AS WELL AS A KNIFE FOR SEPARATING
THE PAPER SECTIONS
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The invention relates to a device for separating paper sections
from a paper
web wound onto a paper roll in accordance with the pre-characterizing clause
of claim
1 as well as to a knife for separating the paper sections in accordance with
the pre-
characterizing clause of claim 7.
Description of the Related Art
[0002] A device for separating paper sections as well as a knife for a
device of
that type is known from DE 20 03 354 A. This prior-art device comprises a
perforating device for dividing the paper band into individual sheets that
contains a
rotatable knife with a perforating cutting edge and ¨ rotating synchronously
with the
latter - with a slotted roller that is equipped with a slit that serves to
accept the radially
outer part of the knife. The cutting edge of the knife is embodied with a
sawtooth
shape. Additionally, the knife comprises a plurality of grooves, into which
engage the
ridges of a counterpart when the knife is moving into the immediate vicinity
of the
slotted roller and is moving past it in a rotating manner. The knife passes
the slotted
roller in a rotating manner, so that the radially outer part of the knife
engages into the
slit and the knife's cutting edge perforates the entire width of the paper
web, with the
exception of those parts of the paper web that are situated opposite the
grooves. The
unperforated portions of the web possess sufficient tensile force to allow the
user to
pull the paper web from the dispenser using a gentle steady pulling force.
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[0003] US 2005/0223860 Al relates to a paper dispenser, which comprises a
housing with a cover, a cylinder drum, a cutter device integrated in the
cylinder drum,
as well as an energy storage mechanism. The cutter device comprises two knifes
that
are arranged spaced some distance apart. The distance between the knives can
be
adjusted via an eccentric element situated in a region between the knives so
that it
becomes possible to deliver sections of different sizes during the dispensing
of a
paper web. Consequently, it is possible to use paper webs with different
tensile
strengths in the same dispenser.
[0004] DE 28 14 792 Al relates to a device for issuing paper sections of a
predetermined length and comprises a device for separating the paper section
from the
paper web wound onto a paper roll and for allowing easy access to the paper
web
following the dispensing of the separated paper section, whereby the device is
operated by pulling on a paper end. The device consists of at least one
cutting roller,
which has a width that corresponds to at least the width of the paper web, and
which
features a cutting line that at least partially encloses an angle a ¨
different from zero ¨
with the generatrix of the cutting roller. The cutting roller comprises a
fixed knife,
which substantially extends over the entire width of the roller and protrudes
from the
roller shell. Associated with the cutting roller is a pressure roller, which
has a slit-
shaped opening that matches the knife arrangement. The two rollers are coupled
to
each other by means of geared wheels, which possess a partial circle diameter
that
corresponds to the roller diameters, and which effect a synchronous movement
of the
roller in such a way that the paper web ¨ stretched tightly across the slit-
shaped
opening ¨ is perforated by a knife, whereby during the course of this cutting
process
the knife penetrates into the slit-shaped opening.
[0005] The knife comprises a cutting edge that is embodied sawblade-like.
According to this prior art, a cutting line of the knife forms an angle a with
the
generatrix of the cutting roller, whereby the angle corresponds to the
constant angle of
inclination of the helical line. Pulling the end of the paper web results in a
rotation of
the cutting roller by way of frictional contact. The knife engaging the paper
web,
which has been stretched tight with the help of the deflection roll, marks the
start of
the separation process of the paper section from the subsequent paper web.
This
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separating process is not completed before the end of the knife engages with
the paper
web and a sufficiently large piece of the following paper web protrudes from
the
dispenser and is easily accessible by hand for the subsequent paper dispensing
process.
=
[0006] EP 1 153 565 Al relates to a mechanism for cutting and providing
sections
of a tape material, in particular paper towels, comprising at least one
cylinder, which
in a support structure is free to rotate about one axis and drags along an end
section of
at least one web, whereby arranged in the cylinder is/are one or several
movable
knife/s, which may protrude from the cylinder for cutting the end section of
the paper
web, whereby the knifes are connected to a shaft that is free to rotate about
one axis,
e.g. oriented parallel to the longitudinal axis of the cylinder. The shaft
comprises at
least one first means, which protrudes from one side of the cylinder and is
free to
rotate about an angular portion of a circumference. The rotational movement is
effected by at least one second means, which shifts along a direction parallel
to the
longitudinal axis of the movable knife and rotates about the axis, whereby the
rotation-translation movement of this second means is synchronized to the
rotational
movement of the cylinder. The rotational movement of the cylinder is initially
started
by pulling on the paper web for a distance equivalent to half a rotation,
whereby
subsequently the second half rotation is caused by a tension spring, which is
connected between a side wall and a geared wheel that is connected to the axle
of the
cylinder. A knife with a sawtooth geometry is used for cutting the paper.
[0007] DE 36 90 545 T1 relates to a dispenser for rolls of flexible tape
material,
comprising a feed roll and a cutter blade. The cutter blade consists of a
series of teeth,
which are arranged some distance from each other along the length of the
blade. In
this prior art, four pairs of teeth are present along the length of the blade,
whereby
these pairs of teeth are separated by cut-outs. Employing this shape of
cutting edge
allows the cutting action that is performed on the web of the flexible band
material
when it is supplied via the feed roll to result in a straight cut that extends
in parallel to
the axis of the feed roll, but this leaves three small sections of the web
uncut, which
correspond to the width of the sections and to the length of the sections
still on the
circumferential surface of the feeder roll.
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[0008] By leaving these small uncut sections of the web, which across the
width
of the web contain a section between each other, serves to maintain the
continuity of
the web, when the web has essentially already been cut but still remains
within the
confines of the dispenser chassis before reaching the dispensing outlet. When
the web
is pulled further out of the dispenser housing by the future user of the now
determined
sheet length, the future user applies a low level of pulling force, which very
easily
separates the spaced-apart uncut sections, which are formed by the
configuration of
the cutting blade and the spacing between the slits arranged in the
circumferential
surface of the feed roll.
SUMMARY OF THE INVENTION
[0009] Starting from this basis, the objective of the present invention
is to further
develop a device of the type mentioned above in a way so that paper webs of
high
strength and elasticity can be cut and dispensed in a reliable and trouble-
free manner.
[0010] Another objective of the invention is to further develop a cutting
knife of
the above-mentioned type in a way so that paper webs of varying strength and
elasticity, in particular paper webs of high strength and elasticity, can be
cut in a
reliable and trouble-free manner.
[0011] This objective is met by the invention for example with the
features of
claim 1.
[0012] Each of the cut-outs comprises two cutting edges, which extend in
parallel
to each other and extend transversely to the longitudinal extent of the knife,
whereby
at least one of the cutting edges is a cutting edge of a group of teeth
bordering the cut-
out. A maximum length of the cutting edges is achieved by embodying the
cutting
edges of the group of teeth bordering the cut-outs in parallel or
substantially in
parallel.
[0013] Along its circumferential surface, the cutting roller comprises
circumferential grooves, each of which corresponds to one of the cut-outs. The
width
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and the depth of the groove preferably correspond to the width and the depth
of the
cut-out.
[0014] In an
especially preferred embodiment, it is intended that the slit-shaped
opening of the pressure roller comprises bridges extending along the
circumferential
direction, whereby a width and a spacing of the bridges corresponds to the
width and
a spacing of the cut-outs in the knife, so that during a relative movement
between the
cutting roller and the pressure roller, the bridges engage into the cut-outs
of the knife
and work together with the adjoining cutting edges in a scissor-like manner.
This
achieves a clean cut in the area of the bridges, which in turn leads to a
smooth and
trouble-free continued transport of the paper section and simplifies tearing-
off the
paper section.
[0015] Further
it is intended in a preferred embodiment that the knife comprises a
knife edge that protrudes from the cutting roller and forms an angled section.
This
ensures that during a relative movement between the cutting roller and the
pressure
roller, at the moment when the knife edge penetrates into the paper web
stretched
along the circumferential surface of the pressure roller, the entry angle will
be set to
an optimum value.
[0016] The
angled section preferably comprises the groups of teeth and is angled
relative to the blade along a deflection line with an angle a with 15 < a <
50 ,
preferably a = 35 .
[0017] It is further intended that the cutting roller comprises two
sections with a
preferably semi-circular cross-section, and that the blade of the knife is
fixed in
position, e.g. clamped, between the semi-circular sections. This
embodiment
facilitates both a simple assembly and an uncomplicated exchange of the knife.
[0018] To achieve an optimum scissor action between the transversely
extending
cutting edges of the knife and the radial bridges of the pressure roller, it
is intended
that the spacing between the bridges of the pressure roller corresponds to the
width of
a group of teeth of the knife edge.
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[0019] The invention further relates to a knife for a device for
separating paper
sections from a paper web wound onto a paper roll, whereby the knife comprises
a
knife blade with teeth and/or groups of teeth, which are arranged spaced apart
along
the length of the knife blade, whereby the teeth and/or groups of teeth are
separated
from each other by cut-outs. The cut-outs have two cutting edges that extend
in
parallel to each other and transversely to the longitudinal extent of the
knife, whereby
at least one of the cutting edges is a cutting edge of a tooth or group of
teeth bordering
the cut-out.
[0020] The invention intends that the cutting edges of the groups of teeth
possess
flanks that rise in the direction toward the cut-outs, which facilitates a
maximum
length of the cutting edges. Flanks that rise in the direction of the cut-out
serve to
achieve an acute angle, which improves the knife's cut into the paper web.
[0021] The teeth or groups of teeth are angled with respect to the blade
along a
deflection line by an angle a with a 15 <a < 55 , preferably a = 35 .
[0022] The teeth or groups of teeth include outer teeth that adjoin the
lateral edge
of the blade as well as at least two inner groups of teeth, whereby a cutting
edge of the
inner group of teeth is embodied with a W-shaped geometry and whereby a
cutting
edge of the outer group of teeth is embodied with a triangular geometry.
[0023] It is further intended that the cutting edges of the inner groups
of teeth,
which border the cut-outs, extend in parallel to each other.
[0024] Further details, advantages, and features of the invention are
not only
found in the claims, the characteristic features listed therein ¨ individually
and/or in
combination ¨ but also in the following description of the figures.
BRIEF DESCRIPTIONS OF DRAWINGS
[0025] The figures show:
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[0026] Fig. 1 shows a front view of a device for dispensing paper
sections of a
predetermined length without the covering hood,
[0027] Fig. 2 shows in a sectional view the device of Fig. 1 along a
section line A-
A, with paper roller, cutting roller, and pressure roller,
[0028] Fig. 3 shows a lateral view of the device of Fig. 1, from the
left, with
gearwheel transmission and return spring,
[0029] Fig. 4a) shows a lateral view of the gearwheel transmission with
return
spring of Fig. 3 in its neutral position,
[0030] Fig. 4b) shows in a sectional view the roller arrangement in its
neutral
position,
[0031] Fig. 5a) shows a lateral view of the gearwheel transmission in the
knife-
entry position,
[0032] Fig. 5b) shows in a sectional view the roller arrangement in the
knife-entry
position,
[0033] Fig. 6a) shows a lateral view of the gearwheel transmission in the
engaged-knife position,
[0034] Fig. 6b) shows in a sectional view the roller arrangement in the
engaged-
knife position,
[0035] Fig. 7a) shows a lateral view of the gearwheel transmission in the
knife-
withdrawal position,
[0036] Fig. 7b) shows in a sectional view the roller arrangement in the
knife-
withdrawal position,
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[0037] Fig. 8 shows a lateral view of the device of Fig. 1; seen from the
right,
with hand wheel,
[0038] Fig. 9 shows a perspective representation of a pressure roller,
[0039] Fig. 10 show a perspective representation of the cutting roller
with knife,
[0040] Fig. 11a) shows a top view onto the knife, and
[0041] Fig. 11b) shows a lateral view of the knife.
DESCRIPTIONS OF THE PREFERRED EMBODIMENTS
[0042] Fig. 1 shows a front view of a device 10, referred to as a paper
dispenser
hereinafter, for dispensing paper sections of a predetermined length. The
device
comprises a housing 12 with a rear wall 14 to be mounted to a wall (not
illustrated), as
well as a covering hood 16. From the rear wall 14 extend holding elements 18,
20 for
accommodating a paper roll 22. From the paper roll 22 issues a paper web 24,
which
is accommodated in a device 26 for separating and dispensing paper sections.
The
device 26 comprises a right-side wall 28 as well as a left-side wall 30, which
are
connected to the rear wall 14. The side walls 28, 30 are connected on the
front side
via a brace 32. From the brace 32 extends along the vertical direction a
pressure
spring 34, which is in contact with a surface 36 of the paper web 24 or the
paper roll
22 and prevents creasing of the paper web 24. The pressure spring is pivotably
mounted around a hinge 38 and can be pivoted laterally to the right or the
left to
facilitate exchanging the paper roll 22. The length of the pressure spring is
such, that
the pressure spring 34 in its laterally pivoted position prevents the covering
hood 16
from closing.
[0043] Fig. 2 shows a sectional view of the paper dispenser 10 along the
section
line A-A. The device 26 comprises a cutting roller 40 with a fixed knife 42
that
extends along the longitudinal axis of the cutting roller as well a pressure
roller 44
with a slit-shaped opening 46, which extends along the longitudinal direction
of the
pressure roller 44, and into which the knife 42 can engage during a
synchronous
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movement of the rollers 40, 44. Each of the rollers 40, 44 is supported in the
side
walls 28, 30 by shaft journals 48, 50. At their ends, each of the shaft
journals 48, 50
features geared wheels 52, 54 or 56, 58, which serve to couple the rollers 40,
44.
[0044] Deflecting rollers 60, 62 are provided for guiding the paper web,
each of
which is supported on an axle 64, 66, which extend between the side walls 28,
30.
[0045] The paper web 24 is deflected by the deflecting rolls 60, 62 and
is guided
along a circumferential section 72 around the pressure roller 44 by
circumferential
guide elements 68, 70. One end 74 of the paper web 24 is guided through a
withdrawal opening 76 in the covering hood 16 and may be grasped by a user. To
ensure that the end of the paper web 74 is guided into the withdrawal opening
76, a
guide element is provided in the area of the withdrawal opening 76 and extends
along
the pressure roller 44 between the side walls 28, 30.
[0046] The guide elements 68, 70 are connected in the area of the cutting
roller 40
by guide lands 71 that extend in the circumferential direction and are
arranged spaced
apart. The guide lands 71 serve to guide the paper web 24 in the region of the
guide
elements 68, 70, where the knife 42 engages into the opening 46 of the
pressure roller
44.
[0047] Fig. 3 shows a lateral view of the paper dispenser 10 and
illustrates the
geared wheel 52 of the cutting roller that is connected to the shaft journal
48, as well
as the geared wheel 56 of the pressure roller 44 that is connected to the
shaft journal
50. The geared wheels 52, 56 form a gear unit with a 1:1 transmission ratio
and effect
a synchronous motion of the rollers in such a way that the paper web 24, which
has
been stretched tightly along the circumferential surface 72 of the pressure
roller 44, is
cut or pierced by the knife 42 when the paper end 74 is being pulled, whereby
during
this cutting operation the knife 42 penetrates into the slit-like opening 46.
[0048] The geared wheel 52 is coupled to the lateral wall 30 via a
tension spring
80 in a way so that a pulling movement acting on the paper end 74 in the
direction of
the arrow 82 in accordance with Fig. 2, effects a rotation of the pressure
roller 44 in
the direction of the arrow 84, on account of a frictional engagement between
the paper
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web 24 and the circumferential surface of the pressure roller. Due to the
coupling of
the geared wheels, the geared wheel 48 is moved in the direction of the arrow
86,
which results in a tensioning of the tension spring 80. After half a rotation
of the
pressure roller 44, the tension spring has reached its maximum tension, so
that during
continued pulling of the paper end 74 the tension spring 80 contracts, which
effects an
automatic further conveyance, which in turn guides a new paper end from the
opening
76.
[0049] Figs. 4 to 7 show individual positions of the cutting roller 40
relative to the
pressure roller 44 when a pulling motion acts on the paper end 74.
[0050] Figs. 4a) and 4b) show the geared wheels 48, 50 and the rollers
40, 44 in a
neutral position, in which the tension spring 80 is relaxed. In this, an
effective line 88
of the tension spring 80 extends substantially perpendicular to a line 90 that
connects
the shaft ends 48, 50. The paper web 24 is in contact with the pressure roller
44 along
its circumferential surface and is pulled tight in the area of the slit-shaped
opening 46.
[0051] Figs. 5a) and 5b) show the geared wheels 48, 50 as well as the
rollers 40,
44 in a knife-engaging position, e.g. after a rotation of approximately 25 ,
whereby
the knife 42 penetrates the paper web and enters into the slit-shaped opening
46,
which starts the separation process. In this position, the knife 42 comes into
contact
with the paper web. Pulling the paper end 74 even further results in an at
last sectional
separation (perforation) of the paper section by the penetration of the knife
42 into the
slit-like opening 46.
[0052] Figs. 6a) and 6b) show the geared wheels 46, 50 and the rollers
40, 44 in
the engaged-knife position, in which the knife 42 is completely accommodated
in the
slit-like opening 46.
[0053] Pulling the paper end 74 results in the tension spring 80 being
further
tensioned, whereby pursuant to Fig. 7a) and Fig. 7b) the knife 42 ¨ after a
rotation of
approximately 120 - is no longer engaged in the slit-like opening 46 (knife
withdrawal position).
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[0054] Pulling the paper end 74 serves to further tension the tension
spring 80,
until the rollers 40, 44 have completed half a rotation. After the effective
line 88 of
the tension spring 80 has crossed the centre of the geared wheel, the
contraction of the
tension spring 80 results in an automatic further conveyance of the paper web
24,
together with the separated paper section. Subsequently, the paper section 74
can be
separated from the paper web 24 along the perforated cutting line.
[0055] Fig. 8 shows a lateral view of the paper dispenser 10 from the
right side
and shows the geared wheels 54 and 58, which are in an engaged position. A
hand
wheel 92 is coupled to the geared wheel 58 for the pressure roller 44. The
hand wheel
92 facilitates a manual operation of the pressure roller 44 for threading the
paper web
24, e.g. after the paper roll 22 has been exchanged.
[0056] The geared wheel 58 of the pressure roller 44 interacts with a
locking lever
94, which is pivotably mounted on a rod 96. The locking lever locks the geared
wheel
58 along the direction of the arrow 94.
[0057] Fig. 9 shows a perspective representation of the pressure roller
44 with the
shaft 50 and the slit-shaped opening 46. The slit-shaped opening 46 extends
along the
longitudinal direction of the pressure roller 44 all along the latter's
longitudinal
extent. The slit-shaped opening 46 comprises four sections 98, 100, 102, 104,
which
are separated by bridges 106, 108, 110 extending in the radial and the
circumferential
direction.
[0058] Fig. 10 shows a perspective representation of the cutting roller 40
with the
fixed knife 42. The knife 42 comprises a knife edge 112 as well as a knife
blade 114,
which is accommodated in the cutting roller 40. In the illustrated embodiment
example, the cutting roller 40 comprises two elements 116, 118, which possess
a
semi-circular cross-section, and in between which the knife blade 114 is
clamped.
[0059] The knife edge 112 comprises four sections 120, 122, 124, 126 in
the form
of teeth, which are separated from each other by cut-outs 128, 130, 132. The
individual sections 120, 122, 124, 126 in the form of teeth of the knife edge
112
engage into the sections 98, 100, 102, 104 of the slit-shaped opening 46,
whereby the
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bridges 106, 108, 110 engage into the cut-outs 128, 130, 132. The outer
surface 134 of
the cutting roller 40 is provided with circumferential grooves 136, 138, 140,
which
corresponding to the cut-outs 128, 130, 134. The outer surface 134 of the
cutting
roller 40 is provided with circumferential grooves 136, 138, 140, which
correspond to
the cut-outs 128, 130, 134. The circumferential grooves 136, 138, 140 engage
into
the guide lands 71 of the circumferential guide elements 68, 70, whereby the
guide
lands extend circumferentially and transversely to the longitudinal axis of
the cutting
roller 42, so that a section of the circumferential surface 134 of the cutting
roller 42
together with the inner surface of the guide lands 71 forms a guide surface,
which
simplifies the guiding of the paper web, in particular during the threading
process.
[0060] Fig. 11a) shows a top view onto the knife 42, comprising the knife
edge
112 as well as the knife blade 114. The knife 42 is embodied as a stamped
part.
[0061] Fig. 11b) shows a lateral view of the knife 42. The knife edge 112
is bent
relative to the knife blade 114 by an angle a, with a in the range of 20 < a
< 60
preferably a = 30 . This ensures that the knife edge 112 enters the slit-
shaped
opening 46 at an optimum angle for cutting the paper web 24.
[0062] In accordance with an aspect of the invention with independent
inventive
merit, the outer sections 120, 126 possess a triangular cutting edge, whereby
sections
142, 144 or 146, 148 of the cutting edge are embodied with an obliquely
downward
shape in the direction towards the lateral edges 150, 152 or the cut-outs 128,
132.
[0063] The invention's embodiment is characterized in that the cutting
edges of
the central sections 122, 124 have flanks 154, 156; 158, 160 that rise in the
direction
of the cut-outs 128, 130, 132, which serves to ensure that cutting edge
sections 162,
164, 166, 168 of the longest possible length are formed adjacent to the cut-
outs 128,
130, 132, whereby the cutting edge sections interact with the bridges 106,
108, 110 of
the pressure roller to cut the paper web in a precise manner, which in turn
facilitates a
simple tear-off action.
[0064] With respect to the invention's embodiment of the knife edge 112,
it
should also be noted that because of the cut-outs 128, 130, 132 the paper web
24 is
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only subjected to a type of perforation, instead of being subjected to a
complete
continuous cut, so that even after the cutting process, the automatic advance
due to the
tension spring 80 is sufficient to transport the paper section 74 to be torn
off out of the
paper dispenser, without any risk of a paper jam. After the perforated paper
section 74
has been dispensed through the opening 76, it may simply be torn off by a
user, which
separates the remaining strands in the paper web 24.
[0065] This requires only minimal pulling forces, whereby a further
conveyance
of the paper web 24 is prevented by the restoring force of the tension spring
80.
[0066] As a result of the invention's embodiment of firstly the knife
edge 112 in
interaction with the slit-shaped opening 46 with the sections 98, 100, 102,
104 as well
as the bridges 106, 108, 110, and secondly by fine-tuning the spring tension
of the
tension spring 80, the invention's embodiment allows the cutting or rather
perforating
of paper webs of different density and strength. In particular, the
invention's paper
dispenser 10 is to convey paper webs with a density of 2 x 25 g per mm2, i.e.
paper
webs that usually can only be used in electrically operated paper dispensers.
In the
prior art, mechanically operated paper dispensers are usually operated using
thin
paper webs with a density of 2 x 17 g per mm2, i.e. single-layer paper.
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