Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
CUTTER HAVING CIRCULAR ROTARY BLADE
BACKGROUND OF THE INVENTION
Field of the Invèntion
The present invention relates to a cutter
having a circular rotary blade which is rotatably
supported at its center on one side of a blàde mounting
portion of a handle. More particularly, the invention
is concerned~wlth a cutter of the above-mentloned type
wherein the resistance to rotation of the circular
blade is adjustable according to the kind of the object
to be cut.
Desaription of the Prior Art
Japanese Utility Model Laid-Open No.
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49674/1983 discloses a cutter having a circular rotary
blade.~ In ~thi~s~ cutter~, the circular blade has a
tendency that the ~peripheral edge of the blade is~
resiliently deformed over the entire circumference in
an undulating manner during the rotation of the blade.
The cut end of the object cut by such an undulating
edge is curved undesirably.
SUMMARY~OF THE INVENTION~
The present invention seeks to provide a
cutter having a circular rotary blade, wherein the
undulation of the circular disc when the disc is
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rotated against a certain resistance is substantially
minimized thereby preventing the cut end of an object
from being curved.
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The invention also seeks to provide a cutter
having a circular rotary blade, wherein the resistance
to the rotation of the blade is adjustable in
accordance with the kind of the object to be cut.
Still urther the invention seeks to provide
a cutter having a circular rotary blade, wherein the
rotation of the circular blade during ~he cutting
operation is controlled by adjustment of the fric-
tioning condition.
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The invention also seeks to provide a cutter
having a circular rotary blade, improved to facilitate
the visual check of the cutting edge of the circular
blade during cutting of the object.
Still further the invention seeks to provide
a cutter having a circular rotary blade, improved to
prevent projection of the cutting edge of the blade
when the cutter is not used.
Still further the invention seeks to provide
a cutter having a circular rotary blade, wherein, when
the cutter is used, the cutting edge of the blade can
be projected beyond a protective member not only
towards the end of the handle but also in the breadth-
wise direction of the handle.
In accordance with the invention, there is
provided a cut-ter having a circular rotary blade
comprising: a handle; a blade mounting portion formed
on one end of the handle, a circular blade secured to
one side of the blade mounting portion and rotatably
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carried at its central portion; a slot or hole having
an opening formed in the blade mounting section at a
position behind the central portion of the circular
blade and corresponding to the circular blade; and a
p~essing member movably received in the slot or hole
and projectable through the opening of the slot or hole
nto pressure contact with one side of the circular
blade.
An operation member is adapted to limit the
movement of the pressing member so as to adjust the
pressure of contact between the pressing member and the
circular blade. The operation member is held in
engagement with the pressing~ member and positioned on
the opposite side of~the blade mounting dispatch to the
circular blade.
The lnvention is further explained by refer-
~-~ ence to the following description of the preferred
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embodiments~ Fe~atures and advantages of the invention
which are not specifically mentioned in the specifica-
tion will be realized by those skilled in the art
carrying out this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a partial front elevational view of
a cutter having a circular rotary blade embodying the
present invention;
Fig. 2 is a sectional view taken ,along the
line II-II of Fig. l;
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Fig. 3 is an exploded perspective view o~ the cutter
showing speciEically a pressing member and an operation
~! member;
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Fig. 4 ls a bottom plan view of a pressing member
showiny an engaging sur~ace thereof; and
Fig. S ls a partial rear elevational view o~ the
cutter in accordance with the invention having a circular
rotary blade.
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~10 DESCRIPTION O~ ~rHE PREERRED EMBODIMENT
~ A preEerred embodiment of the invention will be
`' described hereinunder with reference to the accompanying
~ drawings.
il~ The cutter in accordance with the invention has a
handle l~which~ i6 provided at~its front end with a blade
mounting s~ection 3 on both sides of whiah are formed
suporting portions 4,5. A supporting hole 6 is formed to
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extend from one to the other of these supporting portions 4
and S. A circular blad ~7 is laid on one 4 of the
supporting portions. A stopper screw 8 is extended
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through a cenLral hole 7a ln the blade 7 into the
supporting bore 6 not rotatably. A nut 9 is screwed to the
end o~ the screw 8 projecting out of the o~her supporting
portion 5 until it tigh~tly contacts the surface oE the
suppOrting portion 5. In this state, the circular blade 7
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is pressed at a suitable level of pressure onto the
supporting portion 4 by the tension acting on the stopper
screw 8, so that the blade 7 is rotatable with a certain
level of ~riction resistance,
A slit 10 is formed in the supporting portion 4 of the
blade mounting portion 3. The slit 10 has an opening lOa
which spreads at the rearlside of the central hole 7a of
the blade 7 over an arcuate region corresponding to a
certain circumferential length of the rear part of the
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central hole 7a, and exteods vertically from the supporting
portion 4 to a rear part~of the other supporting portion 5.
A pressing member 11 received in the slot 10 is adapted to
be moved in the directionlsubstantially perpendicular to
: the plane o~ the circular blade 7 such as to be pressed to
the lower side of the blade 7 through the opening lOa.
An operation member 14~has a base 15 which is slidably
superposed to~the surface of the blade mounting section 3
opposite to the blade 7.: The base 15 has a hole 16 which
rotatably receives the supporting por.tion 5. A guide
~: 20 projection 17 projected from the rear end of the base 15
movably fits ln a guide groove 18 formed in the rear end
; : port1on of the blade mounting portion 3.
A manipulation tab 19 projected rearwardly from the
: rear end of the base 15 is slidably superposed to an outer
. surface of the handle i. I A finger-retaining portion 20 is
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formed on the manipulation tab 19. The pressing member 11
and the operation member 14 engage with each other at their
slant engaging surfaces 12,21 serving as cam surfaces. The
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arrangement is such thatla plurality of retaining
projections 13 formed on the engaging surface 12 of the
pressing member 11 are received in corresponding recesses
22 formed in the engaging surface 21 of the operation
` member 14.
When the operation member 14 is rotationally slided in
: 10 the direction of an arrow A in Fig. 5, the pressing member
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11 is raised due to the;cam effect of the slant engaging
surfaces 12,21. As a result, the pr~ssing member 11
projects through the opening lOa of the slot 10 towards the
circular blade 7 so as to make a pressure contact
therewith, so that a frictional resistance of a level
correspondlng to thecontact pressure ls produced to resist
the rotation of:the disc 7. The pressing member 11 is
held at the projecting position due to the engagement
between the projections 13 on the pressing member 11 and
the recesses 22 in the operation member 14. The contact
pressure between the pressing member 11 and the circular
blade 7 is ad~justable through varying the amount of
projection of the pressing member 11 which in turn is
caused by rotating the o~eration member 14 to vary the
position of engagement bltween both slant engaging surfaces
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12 and 21.
The protective member 23 is composed of a disc portion
24 greater in diameter than the circular disc 7 and a base
portion 25 projected from the rear portion of the disc
portion 24. The peripheral portion of the disc 24
constitutes a back-up portion 24a which backs up the
cutting edge portion of the circular blade 7. An aperture
26 large enough to permit the movement of the disc 7 i9
formed in the central portion of the disc portion 24. A
pair of leaf sprlngs~27 extend forwardly from both lateral
~ides of the base portion 25 of the protective member 23.
On the other hand, a leaf spring 29 is loaded to act on a
step surface 28 ~ormed in the rear portion of the bottom
surface oE the base portion 25. A guide projection 30 is
formed on the bottom surface of the:base portion 25 of the
protective member 23~ at a pos1tion ahead of the leaf
spring 29. a pair of gui~de ridges 31 extend longitudinally
of the handle; l~at both sides of the guide projection 30.
The protective member 23 fits in a space defined by
the inner surface of the circular blade 7 and one lateral
side of the blade mounting section 3 of the handle, when
the circular;blade 7 is pressed onto the supporting portion
4 of the blade mounting ~ortion 3. In this state, the
supporting portion 4 is loosely received in the aperture 26
formed in the disc portion 24. A space for allowing the
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movement of the protective member 23 is formed between the
inner peripheral surface of the aperture 26 and the outer
peripheral sUrface of the supporting portion 4. At the
same time, the base portion 25 of the protective member 23
fits in a recess 32 formed in the front end portion of the
handle 1. In this state' the guide projection 30 on the
base portion 25 of the protective member 23 is slidably
received in a guide groove 33 formed in the bottom of the
recess 32 so as to extend longitudinally of the handle 1.
In addition, the leaf springs 27 on both lateral sides of
the base portion 25 resiliently contact opposing side walls 32a
o the recess 32, and the leaf spring 29 provided on the
~- rear end of the base portion 25 abuts the step 32b on the
rear end of the recess 32.
Therefore,~the protective member 23 is swingable to
the left and right about the axis of the guide projection
30 over an area limited by the aperture 26 in the
breadthwise direction of the handle 1, overcoming the
` resilient force exerted by respective leaf springs 27.
The protective member 23 is movable also in the longitudinal
direction of the hanale 1 along the guide groove 33 against
the leaf spring 29.
When the cutter i~ not used, the supporting portion 4
of the blade mounting section 3 is centralized in the
aperture 26 due to balance of resilient forces exerted by
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the leaf springs 27. At the same time, the protectivP
member 23 is urged resillently in the ~orward direction by
the force of the leaf spring 29, but the edge 7b of the
circular blade 7 is prevented by the back-up portion 24a of
the disc portion 24 from projecting outwardly. A cover 34
is placed to overlie the recess 32 with its three legs 34a
retained by retaining holes 35 in the recess 32~ thereby
covering the base portion 25 of the protective member 23.
In the use of the cutter o~ the invention having the
circul~r rotary blade, the pressure of the contact between
the pres~ing member 11 and the circular disc 7 is adjusted
in accordance with the kind of the material to be cut, in a
manner explained before. Subsequently, handle 1 is placed
at a suitable angle of inclination to the object to be cut
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and is moved in the direction of cutting while the circular
dlsc 7 is pressed onto.the object to be cut. As a result,
- ~ the protective member 23;is moved in the~longitudinal or
~;~ breadthwise direction of the handle 1 while making contact
with one s~ide-of the circular blade 7, in accordance with
the angle of inclination of the handle 1. Meanwhile, the
back-up portion 24a slides on the object to be cut, while
the edge 7b of the circular blade 7 projects in any
direction beyond the back-up portion 24a to cut into the
object to be cut. Consequently, the circular blade 7
rolls on the object to be cut, while making a slight ~lip
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~ on the object to be cut. After the use, as the protective
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:: member 23 is automatically retracted to the inoperative
position by the resilient force of the leaf spring 29.
As has been described, since the circular blade of the
invention is pressed at its portion behind the central bore
7a, the cutting edge 7b on the front side o the circular
; blade 7 is not affected by the pressure exerted by the
pressing member so that the object is cut to exhibit a
` linear cut end. At the same time, the pressing member 11
is:always received in the hole 10 ~ormed in the blade
~;. mounting portion 3, while the operating member 14 which
: engages with the pressing member 11 through the cam
: surfaces 12,21 is positioned on the side of the blade
~` : mounting section 3 opposite to the circular blade 7.
Therefore, these: members 11!14 do not project into the
; outer space EaciLng the cir~cular blade 7 so that the edge 7b
of the circular blade 7 is visually~checked easily from the
: upper side during the use o the cutter.
Although the inventi~on has been described through
~specific terms, it is to be understood that the described
.: embodiment of the invention is not exclusive and various :
changes and modifications may be imparted thereto without
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~i departing from the scope of the invention which is limited
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