Note: Descriptions are shown in the official language in which they were submitted.
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COMPACT TRIMMER
Field of the Invention
This invention relates to devices for cutting and
trimming paper and especially to devices which cut by
shearing the paper between two cutting edges.
Background of the Invention
A common paper cutter found in many offices and
businesses is known as the "guillotine" style cutter
and comprises a board having a fixed cutting edge
l0 mounted on the board and a pivoting blade mounted on
the board adjacent to the fixed cutting edge. The
pivoting blade can be raised and lowered manually
relative to the board via a handle positioned opposite
the pivot point of the blade. Paper to be cut is
placed on the board overlying the fixed cutting edge
with the blade in the raised position, and the blade is
then lowered, the blade cooperating with the fixed
cutting edge to shear the paper.
Guillotine-style paper cutters, although
effective, have several disadvantages. Such cutters
are intended to perform relatively heavy-duty cutting
tasks and, therefore, tend to be relatively large,
heavy and expensive. Both the blade and cutting edge
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are made entirely of metal to provide adequate
stiffness and strength for cutting more than a few
sheets of paper. The blade is constantly exposed
presenting a risk of injury, and the method of cutting,
i.e., raising and lowering an exposed blade through an
arc of several inches, is inherently dangerous. The
large size and inherent risk associated with the
guillotine-style paper cutter make such devices
inappropriate for light-duty cutting, such as performed
in the home, in a photographic studio or in many
of f ices .
Summary and Ob-iects of the Invention
A compact trimmer according to the invention
comprises a cutting board which lends itself to
embodiment in small lightweight form. The cutting
board has an upper surface for supporting sheet
material to be cut, and a first cutting edge extending
lengthwise along one side. An elongated guide member
substantially overlies the first cutting edge. The
guide member is spaced above the upper surface, thus
allowing sheet material to pass between the guide
member and the upper surface and overlie the first
cutting edge. A housing having means for engaging the
guide member is movably supported on the guide member
and capable of sliding motion lengthwise along it arid
the first cutting edge. The housing has a sidewall
positioned in a spaced-apart relationship outwardly of
the first cutting edge. A cutting blade, which has a
second cutting edge, is mounted within the housing
between the first cutting edge and the sidewall, a
portion of the second cutting edge being in overlapping
engagement with the first cutting edge. The blade
cooperates with the first cutting edge to cut or trim
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sheet material, such as paper, which is positioned on
the board overlying the first cutting edge. During
cutting, the sheet material is sheared between the
second cutting edge and the first cutting edge when the
housing is moved along the guide member. The blade
portion is held in overlapping engagement against the
first cutting edge by means of a biasing assembly
disposed between the blade and the housing sidewall.
In a preferred embodiment, the cutting blade is
circular and is rotatably mounted within the housing
about an axis of rotation through the center of the
blade. In this embodiment the second cutting edge
extends circumferentially of the blade. The biasing
assembly preferably comprises a hub having a shoulder
upon which the blade is supported. The hub has a
cavity centered on the axis of rotation of the blade
and facing the sidewall. The cavity contains a biasing
member which extends outwardly to engage the facing
sidewall producing biasing forces which react against
the sidewall to keep the second cutting edge against
the first cutting edge.
Preferably the biasing member comprises a spring
and ball, the spring being housed within the cavity and
the ball overlying the spring and extending partially
from the cavity to engage the facing sidewall of the
housing.
It is an object of the invention to provide a
paper trimmer which is safe to operate.
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It is another object of the invention to provide a
paper trimmer suitable for light duty in the home,
studio or office.
It is still another object of the invention to
provide a paper trimmer which is compact and light in
weight.
It is yet another object of the invention to
provide a rotary paper trimmer suitable for personal
use.
It is another object of the invention to provide a
paper trimmer which is relatively inexpensive.
These and other objects of the invention will
become apparent from a consideration of the following
drawings and detailed description of preferred
embodiments of the invention.
Brief Description of the Drawings
Figure 1 is an isometric view of a compact trimmer
according to the invention;
Figure 2 is a plan view of the trimmer shown in
Figure l;
Figure 3 is a sectional view on an enlarged scale
taken along line 3-3 of Figure 1;
Figure 4 is a sectional view taken along line 4-4
of Figure 3; and
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Figure 5 is an exploded isometric view of a detail
of the trimmer shown from below.
Detailed Description of the Preferred Embodiment
Figure 1 is an isometric view of a compact trimmer
5 10 according to the invention. Trimmer 10 comprises a
cutting board 12 which provides an upper surface 14
upon which to place sheet material such as paper,
photographs and the like for cutting or trimming.
Board 12 preferably has indicia l6 displayed thereon to
aid in the alignment of the sheet material and insure
precise, measured cutting. One or more raised
shoulders 18 are formed adjacent to upper surface 14 to
provide a convenient edge against which the sheet
material can be squarely aligned with respect to the
cutting first cutting means described below.
Preferably, board 12 is injection molded from plastic
material such as a high impact styrene which allows for
a strong, stiff but lightweight design. Alternatively,
ABS plastic is a suitable material.
As seen in Figures 1 and 2, a first cutting means
in the form of a rectilinear cutting edge 20 is
arranged lengthwise along a first side of board 12.
Figures 3 and 4 show a preferred embodiment of cutting
edge 20, formed as an edge of an elongated member 22,
preferably a metal strip of stainless steel. Elongated
member 22 is mounted flush with upper surface 14 and
preferably attached to board 12 by means of screws 24
(Figure 3). First cutting edge 20 extends clear of
board 12 as best shown at 26 in the cross sectional
view of Figure 3.
*rB
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Figures 1, 2 and 3 show a preferred guide means,
an elongated guide member 28 mounted on board 12,
substantially overlying elongated member 22. As seen
in Figure 3, guide member 28 includes a guide rail 30
extending upward from the guide member. Preferably,
guide rail 30 includes a relatively wide head 30a
supported on a narrow upright 30b thus giving the guide
rail a "T" shaped cross section further described
below. Guide member 28 is preferably molded from a
transparent styrene and is attached to board 12 by any
suitable means such as by inserting tabs (not shown)
projecting from its ends into slots (not shown) formed
in raised portions 32 of board 12 located adjacent to
each end of guide member 28 and seen in Figures 1 and
2. Guide member 28 should be positioned to be spaced
above upper surface 14 and elongated member 22, and
rail 30 should extend beyond the shoulders 18 to the
positions marked "A" for reasons explained below.
Figures 1 and 5 show a blade housing 34 for
mounting a second cutting means, the second cutting
means~being a blade and preferably a circular cutting
blade 36. The housing has means 38 for engaging guide
rail 30 for~sliding motion along the length of guide
member 28. As seen in Figure 5, rail engaging means 38
preferably comprises two pairs of spaced flanges 40a
and 40b defining a pair of spaced apart "T" shaped
apertures 42 through which guide rail 30 extends,
thereby constraining housing 34 to move linearly along
a predetermined path defined by the guide rail, all
other motions being prevented. Housing 34 is
preferably molded from ABS plastic material and has
raised gripping segments 44 to facilitate manual
gripping to effect the sliding motion.
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Rail engaging means 38 further comprises standoffs
41 which extend downwardly from housing 34 as seen in
Figures 3 and 5. Standoffs 41 are preferably hemi-
cylindrical in shape and serve to space the lower
portion of the housing away from elongated guide member
28 in order to reduce friction between the two
components during relative motion.
Cutting blade 36 is preferably a rotary cutting
blade made of steel, 12L-14 being preferred due to its
ready machinability. The blade has a circular shape
and a second cutting edge 46 is disposed about its
circumference. Blade 36 is rotatably mounted Within
housing 34 on an axle 48 oriented perpendicularly to
guide rail 30. Axle 48 rides in two bearings 50,
preferably integrally molded within housing 34 and
flanking guide rail 3U, as best seen in cross section
in Figure 3. Blade 36 is supported on a shoulder 52
extending from axle 48. The blade is preferably staked
onto the shoulder, the staking preventing it from
rotating independently of axle 48.
To rotate blade 36 an annular friction collar 54,
seen in Figures 3-5, is positioned coaxially on axle 48
between bearings 50. Collar 54 engages the top of
guide rail 30 when housing 34 is moved along guide
member 28. Frictional forces between the collar and
the guide rail cause the axle to turn as the housing
moves relative to the guide rail, the arrangement
functioning as a toothless rack and pinion.
Preferably, axle 48 is made of metal and collar 54 is
of a resilient material having a relatively high
coefficient of friction, such as rubber, to provide for
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positive frictional contact between the collar and the
rail as well as the collar and the axle.
Blade 36 is mounted adjacent to and aligned
parallel to first cutting edge 20 with a portion 56 of
second cutting edge 46 in overlapping engagement with
first cutting edge 20, as seen in Figure 3. Because
the blade overlaps the first cutting edge, it is
necessary to provide positions, denoted "A" at either
or preferably both ends of guide member 28 wherein
guide rail 30 extends beyond the boundary of upper
surface 14 marked by shoulders 18. When housing 34 is
in either position marked "A", blade 36 does not
obstruct the gap 58 (seen in Figure 3) between guide
member 28 and elongated member 22 at any point along
upper surface 14. This allows sheet material to be
positioned anywhere on upper surface 14 in overlying
relation with first cutting edge 20 without the need to
pivot guide member 28 out of the way as required for
other trimmers.
Effective shearing of the sheet material requires
a biasing means for biasing blade 36 against first
cutting edge 20, thus keeping the overlapping blade
portions in contact. The biasing means is preferably
in~the form of biasing assembly 60 (see Figures 3 and
5), which extends from axle 48 and is interposed
between blade 36 and a sidewall 62 of housing 34.
Sidewall 62 is spaced outwardly from blade 36 on the
side of the blade facing away from the first cutting
edge 20, thus, providing a stiff structure against
which to react the biasing forces of biasing assembly
60.
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As seen in Figures 3 and 5, biasing assembly 60
preferably comprises a hub 64 extending from axle 48
and disposed between blade 36 and housing sidewall 62.
Hub 64 has a cavity 68 preferably centered on the axis
of rotation 70 of blade 36 as defined by axle 48.
Cavity 68 contains a biasing member, preferably
comprising a coil spring 72 and a ball 78, made of
steel for durability. Spring 72 resides within cavity
68 and ball 78 overlies the spring and extends
partially out of the cavity, as seen in Figure 3.
Spring 72 forces ball 78 against housing sidewall 62,
which serves as a reaction point for the spring,
forcing blade 36 into overlapping interengagement
against first cutting edge 20. Axle 48 is free to
slide laterally in bearings 50 to ensure that spring 72
and ball 78 provide effective biasing action to keep
the cutting edges engaged. Ball 78 is sized to fit
easily within cavity 68 and its spherical shape insures
that it will not cause the axle to bind or lock and
prevent rotation of the axle and rotary blade.
In operation, sheet material, for example, paper,
is placed on upper surface 14 with the portion to be
trimmed overlying the first cutting edge 20. The
operator can align the paper using shoulders 18 and/or
the indicia 16 for. precision cutting. Preferably
housing 34 is located at either position marked "A" on
guide member 28 so that blade 36 does not interfere
with the placement of the paper on the upper surface.
once the paper is placed as desired, the operator grips
housing 34 and slides it along guide member 28. Within
the housing, collar 54 frictionally engages the top of
rail 30 and forces blade 36 to turn via axle 48. Blade
36 encounters the portion of the paper overlying first
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cutting edge 20 and the paper is sheared apart between
the second cutting edge 46 and the first cutting edge
20.
The compact trimmer according to the invention is
5 designed to fill a multi-purpose role, but is
particularly suited to light duty, cutting up to five
sheets of paper safely, cleanly and precisely.
Components such as the board, housing and guide member
are preferably molded from plastic material, thus,
10 providing relatively high strength and stiffness and
light weight. Metal is preferably used for the cutting
edges, the axle, spring and ball for durability. The
combination of materials and compact design provides a
trimmer which is safe and easy to use and readily
affordable.
