Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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l TUBULAR KNIFE
¦ Background of the Invention
¦ The instant invention relates to cutting knives, and
¦more particularly to a tubular knife.
¦ It is well known to form cutting devices by moving two
¦opposed cutting edges past each other in scissor-like fashion.
¦However, in industrial applications, such as in electrostatic
photocopiers, where a substantial quantity of cutting takes
~place, it is desirable to have a.cutting device which will
¦perform well for an extended period of time with virtually no
~need for maintenance or adjustment.
~Summary of the Invention
¦. Accordingly, the instant invention provides a tubular
¦knife. The knife comprises a stationary, inner cylindrical .
member having a slot extending substantially longitudinally
thereof, the slot having a longitudinally extending upper edge
and a longitudinally extending lower cutting edge, a rotatable,
outer tube concentric and substantially contiguous with the
inner member, the outer tube having a slot substantially
co-extensive with the slot of the inner member, the outer tube
slot having an upper cutting edge inclined at a slight angle
with respect to the lower cutting edge of the inner member
slot, means for biasing the outer tube to a position wherein .
the slot of th.e outer tube is substantially aligned with the
slot of the inner member, and means for rotating the upper
cutting edge of the outer slot past the lower cutting edge of
the inner slot. i-.
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Brief Description of the Drawings
Fig. 1 is a vertical sectional view of a tubular knife
according to the instant invention for cutting paper together
with other paper handling apparatus;
Fig. 2 is similar to Fig. 1 except that it shows the
paper immediately after it has been cut;
Fig. 3 is an enlarged view of the paper cutting area
shown in Fig. 2;
Fig. 4 is a sectional view taken on the vertical plane
indicated by the line 4-4 in Fig. 1;
Fig. 5 is a sectional view taken on the vertical plane
indicated by the line 5-5 in Fig. 1;
Fig. 6 is a radial sectional view of an alternative
embodiment of a tubular knife according to the instant
invention;
Fig. 7 is similar to Fig. 6 except that the outer tubular
member of the knife is shown rotated to a second position.
Detalled Description
In describing the preferred embodiment of the instant
invention, reference is made to the drawings, wherein there
is seen in Fig. 1 a pair of feed rollers 10 and 12 rotatable in
the directions indicated for feeding a web of paper 14 to a
tubular knife generally designated 16 through upper and lower
paper guides 18 and 20 respectively which extend into the knife
16. Once the paper web 14 is cut by the knife 16, the severed
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portion 22 (see Fig. 2) is pulled away from the knife 16 by
a second pair of feed rollers 24 and 26 rotatable in the
directions indicated between a second pair of paper guides
27 and 29.
The tubular knife 16 includes rotatable outer tubular
member 28 and a stationary concentric inner tubular member
30 contiguous with the outer tubular member 28. When the
knife 16 is not actuated for cutting purposes, the outer tubular
jllmember 28 is biased by a torsion spring 29 (see Figs. 4 and 5)
to the position shown in Fig. 1 designated the home position.
The inner tubular member 30 has a rear (relative to the
direction of movement of the paper web 14) slot 32 while the
,outer tubular member 28 has a rear slot 34 which is larger
in both circumferential directions than the slot 32 of the
,inner tubular member 30. It is only necessary, however, that
the bottom edge 36 of the outer slot 34 extend sufficiently
circumferentially below the paper web 14 so that when the outer
tubular member 28 is actuated by a solenoid 38 to rotate
¦clockwise in order to cut the paper web 14 the bottom edge 36
does not come in contact with the paper web 14.
As best seen in Fig. 5, the inner tubular member 30
has a forward (relative to the direction of the movement of the
¦paper web 14) slot 40 having a horizontal upper edge 42 and
a horizontal lower edge 44, while the outer tubular member
28 has a forward slot 46 having an inclined upper edge 48
and a horizontal lower edge 50. In order that appropriate
pressure is brought to bear between the outer and inner
tubular members 28 and 30 in the cutting region, a pair of
hemispheres 52 (only one is shown) are formed on a front
loading spring 54 while a second pair of hemispheres 56 are ,
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. ¦ formed on a rear loading spring 58. As seen in Fig. 1, when
¦ the outer tubular member 28 is biased to the home position,
¦ all four slots 32, 34, 40 and 46 are aligned to permit paper
¦ to pass therethrough.
To understand the cutting action, reference is made to
Fig. 3, wherein the paper web 14 is seen at the instant it is
severed. The inclined upper edge 48 of the outer slot 46
rotated past the horizontal lower edge 44 of the inner slot 40,
so that a scissor action is effected upon the paper web 14 as it
exits from the knife 16. The rotation of the outer tubular
member 28 is effected by the solenoid 38 through an actuating arm
39- The scissor action comes about by virtue of the upper edge
48 being inclined. The severed portion 22 of the paper web 14 is
then removed through the paper guides 27 and 29 by the feed
¦rollers 24 and 26. Once the cutting action of the outer tubular
¦member 28 is completed, the coil spring 29 returns the outer
¦tubular member 28 to its home position preparatory to another
cutting cycle.
It has been found that in order for the outer tubular
member 28 to possess sufficient rigidity, it should be at
least 1/16 inch thick when formed from stainless steel. Of ¦
course other metals may be used, and depending on their
rigidity, other thicknesses may be required. The foregoing . .
also applies to the inner tubular member 30. However, it
should be understood that the inner tubular member 30 can
have almost any thickness, and could even appear in cross
section as two half circles. If the inner tubular member 30
assumes the two half circles configuration, then it is possible
to eliminate the paper guides going through the tubular knife .
assembly 16. -
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¦ Although the outer tubular member 28 is shown to
constitute a full circle in cross section, it is only necessary
that its cross section exceed 180 by an amount sufficient to
assure that the outer tubular member 28 can rotate snugly about
the inner tubular member 30. Cross sections of 240 for the
outer tubular member 28 are adequate. Accordingly, tube or
tubular member is hereby defined and understood to include cross
sections less than 360~.
Although the preferred embodiment described hereinabove
effects a cutting action by means of rotating the outer tubular ~d
member 28, it is also possible to employ a rotatable, inner
cylindrical member with a fixed, outer tubular member. Further-
more, regardless of which of the inner and outer members is
rotated, it is possible to cut the web of paper or other sheet
material either as it enters the knife or as it exits from the
knife, depending upon the nature of the material to be cut.
¦Preferably, as seen in Fig. 3, the material would be cut as it
¦exits from the knife. It is also obvious that the direction of
¦rotation of the rotatable member and the various upper and lower
¦cutting edges of the various slots may be reversed, thereby
¦effecting cutting in an opposite direction, i.e. from low to
¦high instead of from high to low as seen in Fig. 3. However, all
¦these opposite cutting actions are virtually equivalent to each
other.
The preferred embodiment described above shows one
forward slot 46 on the outer tubular member 28. However, if
two forward slots are employed, substantially parallel to
each other, properly spaced and angled, the cutting life of
the entire mechanism can be doubled since the reciprocating
motion of the outer tubular member 28 makes it possible to
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cut paper on the upward stroke as well as ~he downward stroke
of the outer tubular member. With two forward slots on the
outer tubular member, the upper as well as the lower edge of
the inner tubular member would be used for cutting. Accordingly,
the alternative embodiment seen in Fig. 6 showns a tubular
knife 116 having a rotatable outer tubular member 128 and a
stationary concentric inner tubular member 130 contiguous with
the outer tubular member 128. The inner tubular member 130
has a rear slot 132 and a forward slot 140. The upper edge
142 and the lower edge 144 of the forward slot 140 are both
horizontal and both function as cutting edges as explained
hereinafter. The outer tubular member 128 includes an extended
rear slot 134, a first forward slot 146 and a second forward
slot 147. The upper edge 148 of the first forward slot 146
and the lower edge 149 of the second forward slot 147 are both
j inclined. Accordingly, when the outer tubular member 128 is
¦rotated by conventional means clockwise from the home position
¦ of Fig. 6 to the home position of Fig. 7, a scissor action is
¦ effected between the inclined upper edge 148 and the horizontal
¦lower edge 144. Similarly, when the outer tubular member 128
¦ is rotated by conventional means counter-clockwise from the
jhome position of Fig. 7 to the home position of Fig. 6, a
scissor action is effected between the inclined lower edge
1.49 and the horizontal upper edge 1i2.
While the invention has been described with reference
to the structures disclosed herein, it is not confined to the
l details set forth and this application is intended to cover
¦ such modifications or changes as may come within the purpose
of the improvements or the scope of the following claims.
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