U.S. patent application number 10/834533 was filed with the patent office on 2004-11-04 for blade sharpener for household use.
This patent application is currently assigned to Kai R & D Center Co., Ltd.. Invention is credited to Ikegaki, Ikuo, Shimizu, Takashi, Tanaka, Katsuya.
Application Number | 20040219868 10/834533 |
Document ID | / |
Family ID | 33308204 |
Filed Date | 2004-11-04 |
United States Patent
Application |
20040219868 |
Kind Code |
A1 |
Ikegaki, Ikuo ; et
al. |
November 4, 2004 |
Blade sharpener for household use
Abstract
A blade sharpener for grinding a kitchen knife, etc. in which
two separate rotary shafts are provided in parallel, at least one
whetstone is mounted on each one of the rotary shafts, the
circumferential surface of the whetstone forms a grinding surface,
the whetstone on one rotary shaft and the whetstone on the other
rotary shaft are positionally shifted in the axial direction of the
rotary shafts, and the cutting edge of the blade of kitchen knife
is ground by moving the blade in the axial direction of the rotary
shafts while applying the cutting edge to the grinding surfaces of
the whetstones.
Inventors: |
Ikegaki, Ikuo; (Seki-shi,
JP) ; Shimizu, Takashi; (Seki-shi, JP) ;
Tanaka, Katsuya; (Seki-shi, JP) |
Correspondence
Address: |
KODA & ANDROLIA
2029 CENTURY PARK EAST
SUITE 1430
LOS ANGELES
CA
90067-3024
US
|
Assignee: |
Kai R & D Center Co.,
Ltd.
|
Family ID: |
33308204 |
Appl. No.: |
10/834533 |
Filed: |
April 29, 2004 |
Current U.S.
Class: |
451/185 |
Current CPC
Class: |
B24B 3/54 20130101 |
Class at
Publication: |
451/185 |
International
Class: |
B24B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 1, 2003 |
JP |
2003-126676 |
Claims
1. An electric blade sharpener in which a whetstone is provided on
a rotary shaft and is rotated by a motive force of a motor and a
cutting tool is sharpened when moved in an axial direction of the
rotary shafts while applying a cutting edge of the cutting tool to
a grinding surface of the whetstone, wherein: two separate rotary
shafts are provided; and at least one whetstone is mounted on each
of said two rotary shafts, a circumferential surface of said
whetstone forming a grinding surface, and a whetstone on one of
said two rotary shafts and a whetstone on another one of said two
rotary shafts being positionally shifted in an axial direction of
said rotary shafts.
2. The electric blade sharpener according to claim 1, wherein said
whetstone on one of said two rotary shafts and said whetstone on
another one said two rotary shafts partially overlap between said
two rotary shafts.
3. The electric blade sharpener according to claim 1, wherein said
whetstone is in a cylindrical shape, and the grinding surface is at
right angles with respect to a planar portion of said
whetstone.
4. The electric blade sharpener according to claim 1, wherein said
whetstone on at least one of said two rotary shafts is in a
truncated cone shape and is provided so that a smaller diameter
portion of said truncated cone shape whetstone faces in a direction
in which said cutting tool is moved in the axial direction of said
rotary shafts.
5. The electric blade sharpener according to claim 1, wherein each
one of said whetstones is formed with a beveled surface at a corner
between the grinding surface and a planar portion that faces a
direction in which said cutting tool is moved during grinding of
said cutting tool.
6. The electric blade sharpener according to claim 1, wherein at
least two whetstones are mounted on each one of said rotary
shafts.
7. The electric blade sharpener according to claim 6, wherein said
whetstones provided in a direction in which said cutting tool is
moved for grinding are arranged so that whetstones on a downstream
side of a movement for grinding of said cutting tool is provided
with finer grinding surfaces than whetstones on an upstream
side.
8. The electric blade sharpener according to claim 6, wherein said
at least two whetstones provided on each one of said rotary shafts
are arranged so that a whetstone on a downstream side of a movement
for grinding of said cutting tool is provided with a finer grinding
surface than a whetstone on an upstream side.
9. The electric blade sharpener according to claim 6, wherein said
whetstones are respectively mounted on sleeve elements that have
same configurations and said sleeve elements are provided on said
rotary shafts.
10. The electric blade sharpener according to claim 1, wherein said
whetstone is rotated in a direction in which the grinding surface
of said whetstone rubs said cutting tool upward during
grinding.
11. The electric blade sharpener according to claim 1, wherein said
rotary shafts are rotated in the same direction.
12. The electric blade sharpener according to claim 1, wherein said
motor is an alternating-current motor.
13. A sharpener for a cutting tool in which a blade of a cutting
tool is brought into a blade insertion groove and grinding is
performed by moving the cutting tool, said sharpener is provided
with a heel end receiving section formed at one end of said blade
insertion groove, said heel end receiving section having a width
that is larger than a width of said blade insertion groove that is
formed continuously to said heel end receiving section.
14. The sharpener according to claim 13, wherein said heel end
receiving section is provided adjacent to where a handle of a
cutting tool is located when a blade of said cutting tool is
inserted in said blade insertion groove.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a blade sharpener for
grinding at home the blade of a cutting tool such as a kitchen
knife.
[0003] 2. Prior Art
[0004] In a conventional electric blade sharpeners for household
use, a circular disk-form whetstone is mounted on a single rotary
shaft connected to the motor and is rotated, and the blade of a
cutting tool such as a kitchen knife is sharpened by applying the
cutting edge to the circular grinding surface of the rotating
whetstone. This structure is disclosed in, for example, Japanese
Patent Application Laid-Open (Kokai) No. H9-131649.
[0005] On the other hand, in manual blade sharpeners, the blade of
a cutting tool is brought into a blade insertion groove of the
sharpener, and the cutting tool is repeatedly moved back and forth
so that the cutting edge is sharpened as disclosed in Japanese
Utility Model Registration No. 2,547,576.
[0006] In such electric blade sharpeners that use whetstones
mounted on a single rotary shaft as described above, the cutting
edge of a kitchen knife is sharpened by way of applying the cutting
edge to the circular grinding surface of the whetstone.
Accordingly, grinding is performed only on one surface of the
blade. As a result, there are problems. First, burrs are formed on
the other surface of the blade (which is not ground). Accordingly,
this other surface must also be lightly ground during finishing
process. Furthermore, since the whetstone is mounted on a single
rotary shaft, and grinding is performed by the circular grinding
surface of this whetstone, the grinding that is done while moving
the kitchen knife is performed by the same whetstone. As a result,
the grinding conditions are not varied while moving the kitchen
knife.
[0007] In the above-described manual blade sharpener, circular
whetstones are mounted on supporting shafts that are provided
parallel to the direction in which the blade insertion groove
extends; and it is necessary to employ bearing members that hold
both ends of each one of the supporting shafts. As a result, spaces
for the bearing members are required, and thus the whetstones
cannot be provided so as to be in contact with the end of the blade
insertion groove, and a certain distance generates between the end
of the blade insertion groove and the whetstones. Some knifes,
however, cannot be sharpened by such a blade sharpener. In
particular, there are substantially two types of knives: in one
type the blade has a constant thickness for its entire length, and
in another type the blade has an area, near the handle, that is
larger in thickness than other portions. When a knife that has,
near the handle, an area that is thicker than other portion is
sharpened by the above-described manual sharpener, since the blade
insertion groove is small in width, such a thicker portion of the
blade is not brought into the blade insertion groove. As a result,
a portion of the blade that is positioned between the end portion
of the blade insertion groove and the whetstones does not make
contact with the whetstones and is not ground.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention is to provide a grinding
apparatus for household use that efficiently grinds and sharpens a
cutting tool such as a kitchen knife.
[0009] One object of the present invention is to provide an
electric blade sharpener which, by performing grinding
simultaneously on both sides of the cutting edge of a cutting tool
such a kitchen knife, scissors, etc. while being moved, makes it
possible to sharpen the cutting tool by means of a one-stroke
operation, i.e., merely by moving the cutting tool one time in one
direction, without any need to apply the cutting edge to the
whetstone many times.
[0010] Another object of the present invention is to provide a
cutting tool sharpener which, using a plurality of whetstones,
makes it possible to perform finishing sharpening of a cutting tool
by a one-stroke operation with, for instance, a coarse whetstone
and a finishing whetstone in combination without any need to apply
the cutting edge to the whetstones repeatedly.
[0011] Still another object of the present invention is to provide
a cutting tool sharpener that sharpens even a cutting tool that has
a thick portion near the handle.
[0012] The above objects are accomplished by a unique structure of
the present invention for a an electric blade sharpener in which a
whetstone is mounted on a rotary shaft that is rotated by the
motive force of a motor; and in the present invention:
[0013] two separate rotary shafts are provided in parallel,
[0014] at least one whetstone is mounted on each one of the rotary
shafts,
[0015] the circumferential surfaces of the whetstones form the
grinding surfaces of the respective whetstones,
[0016] the whetstone on one rotary shaft and the whetstone on the
other rotary shaft are positionally shifted in the axial direction
of the rotary shafts, and
[0017] a cutting tool is sharpened by moving the cutting tool in
the axial direction of the rotary shafts while applying the cutting
tool (or the cutting edge thereof) to the grinding surfaces of the
respective whetstones.
[0018] Furthermore, in the present invention, the whetstone on one
rotary shaft and the whetstone on the other rotary shaft partially
overlap between the two rotary shafts. In addition, the whetstones
have a cylindrical shape, and the grinding surfaces are at right
angles with respect to the planar or flat portions of the
whetstones.
[0019] The whetstone on at least one of the rotary shafts may have
a truncated cone shape, and this whetstone is installed so that the
smaller diameter side of this cone shape whetstone faces in the
direction in which the cutting tool is moved during the grinding
process.
[0020] Furthermore, the corner of each one of the whetstones which
is between the planar portion and the grinding surface and faces
the direction in which the cutting tool is moved to be ground
during the grinding process of the cutting tool is beveled.
[0021] In the present invention, two whetstones can be mounted on
each rotary shaft.
[0022] In the present invention, the whetstones that are lined up
in the direction in which the cutting tool is moved for grinding
are provided so that the whetstones on the downstream side of the
movement for grinding of the cutting tool are provided with finer
grinding surfaces so as to grind the cutting edge of the cutting
tool smoother than the whetstones on the upstream side do.
[0023] Furthermore, two whetstones mounted on each one of the
rotary shafts are provided so that the whetstone on the downstream
side of the movement for grinding of the cutting tool is provided
with a finer grinding surface so as to grind the cutting edge of
the cutting tool smoother than the whetstone on the upstream side
does.
[0024] Furthermore, the whetstones can be mounted sleeve elements
of same configuration, and these sleeve elements having whetstones
are fastened to the rotary shafts. The sleeve elements of the same
configuration having whetstones thereon are respectively fastened
to the rotary shafts so that the sleeve elements are positionally
shifted in the axial direction.
[0025] In the present invention, in addition, the whetstones on
both rotary shafts respectively are rotated in a direction in which
the grinding surfaces rub the cutting tool upward during grinding
process.
[0026] The rotary shafts are rotated in the same direction, and the
motor used in the present invention is an alternating-current
motor.
[0027] The above objects are further accomplished by a unique
structure of the present invention for a cutting tool sharpener in
which the blade of a cutting tool is brought into a blade insertion
groove and the grinding is performed by moving the cutting tool;
and in this sharpener, a heel end receiving section is provided at
one end of the blade insertion groove, and this heel end receiving
section is formed so that its width is larger than the width of the
blade insertion groove that is formed continuously to the heel end
receiving section. The heel end receiving section is provided
adjacent to where the handle of a cutting tool is positioned when
the blade of the cutting tool is brought into the blade insertion
groove.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a perspective view of the main body of the cutting
tool sharpener according to the present invention;
[0029] FIG. 2 is a perspective view of a part of the interior of
the sharpener main body;
[0030] FIG. 3 is a perspective view of the whetstone box;
[0031] FIG. 4 is a perspective view of the whetstone box seen from
the bottom;
[0032] FIG. 5 is a perspective view of the inside of the whetstone
cover;
[0033] FIG. 6 is a perspective view of the sharpener with the
whetstone cover removed;
[0034] FIG. 7 is a top view of the sharpener with the whetstone
cover removed;
[0035] FIG. 8 shows the manner of a whetstone arrangement;
[0036] FIG. 9 is a perspective view of whetstones and a sleeve
element;
[0037] FIG. 10A is an enlarged front view of the tubular body, and
FIG. 10B is a sectional view taken along the line 10B-10B in FIG.
10A;
[0038] FIG. 11 is an enlarged perspective view of the stopper
device;
[0039] FIG. 12 is an overall perspective view of the sharpener of
the present invention;
[0040] FIG. 13 is a perspective view of the interior of the
sharpener;
[0041] FIG. 14 shows the belt transmission mechanism;
[0042] FIG. 15 is another overall perspective view of the sharpener
of the present invention;
[0043] FIG. 16 is a perspective view of the sharpener of the
present invention seen from the bottom;
[0044] FIG. 17 is a front view of the sharpener with the cover
mounted;
[0045] FIG. 18 is a top view of the sharpener with the cover
mounted;
[0046] FIG. 19 is a perspective view of the sharpener having a heel
end receiving section; and
[0047] FIG. 20 shows a knife having a thick heel end.
DETAILED DESCRIPTION OF THE INVENTION
[0048] Embodiments of the grinding apparatus or sharpener for
cutting tools of the present invention will be described below with
reference to the accompanying drawings. The description will be
made on a sharpener for a kitchen knife (merely called "knife"
below).
[0049] The sharpener comprises a sharpener main body 1 shown in
FIG. 1, a whetstone box 2 shown in FIG. 3, and a cover 3 shown in
FIG. 18.
[0050] The whetstone box 2 is detachably attached to the sharpener
main body 1. The interior of the whetstone box 2 with the whetstone
cover 4 removed is shown in FIGS. 6 and 7. Two separate rotary
shafts 5 and 6 are provided parallel to each other inside the
whetstone box 2 by being supported at their respective end
portions.
[0051] A first whetstone 7 and a third whetstone 8 are mounted on
one rotary shaft 5, and a second whetstone 9 and a fourth whetstone
10 are mounted on the other rotary shaft 6. When a knife is ground,
the knife is moved so that the first whetstone 7 first contacts the
cutting edge of the knife, the second whetstone 9 next contacts the
cutting edge, the third whetstone 8 next contacts the cutting edge,
and then the fourth whetstone 10 contacts the cutting edge at
last.
[0052] The respective whetstones 7, 8, 9 and 10 have a cylindrical
shape; and in each one of the whetstones, the corner between the
planar or flat portion and the circumferential surface that
constitutes a grinding surface of the whetstones is beveled, so
that the corner has an inclined surface 11.
[0053] The first whetstone 7 and second whetstone 9 are formed from
the same material and have the same roughness; and these whetstones
have a coarseness of, for example, #120 and perform rough grinding.
The third whetstone 8 and fourth whetstone 10 have a finer grain;
and these whetstones have a coarseness of, for example, #180 and
perform finishing grinding so that they grind the cutting edge
smoother than the first and second whetstones 7 and 9 do. The third
whetstone 8 and fourth whetstone 10 are made of the same
material.
[0054] In other words, the whetstones, which are lined up in the
direction shown by arrow in FIG. 7 in which the knife is moved to
be ground during grinding, are provided so that the whetstones 8
and 10 that are on the downstream side of the movement for grinding
of the knife have finer grinding surfaces so that they grind the
cutting edge of the knife smoother than the whetstones 7 and 9 that
are on the upstream side. Furthermore, the whetstones 7 and 8 on
the rotary shaft 5 are provided so that the whetstone 8 that is on
the downstream side of the movement for grinding of the knife is
provided with a finer grinding surface so as to grind the cutting
edge of the knife smoother than the whetstone 7 that is on the
upstream side, and the whetstones 9 and 10 on the rotary shaft 6
are provided so that the whetstone 10 that is on the downstream
side of the movement for grinding of the knife is provided with a
finer grinding surface so as to grind the cutting edge of the knife
smoother than the whetstone 9 that is on the upstream side.
[0055] The present invention is, however, not limited to the
construction as described above. All of the whetstones 7, 8, 9 and
10 can be different in coarseness. In addition, they can be
arranged so that grain of the whetstones becomes finer in the order
from the first whetstone 7 to the fourth whetstone 10.
[0056] The shape of the whetstones is not limited to a cylindrical
shape. The whetstones mounted on at least one of the rotary shafts
5 and 6 can have a truncated cone shape as shown in FIG. 8. In this
case, a larger whetstone 12 and a smaller whetstone 13 are used,
and the circumferential surfaces of the whetstones 12 and 13 are
lined up along a single straight line. In use, the cutting edge of
the knife first contacts the larger whetstone 12 and then contacts
the smaller whetstone 13; thus as see from FIG. 8, the smaller
diameter sides of the cone shape whetstones face in the direction
in which the knife is moved or drawn to be ground during the
grinding process. As a result, the cutting edge angle can be
slightly increased in the finishing stage of the sharpening, thus
increasing the strength of the cutting edge.
[0057] As shown in FIG. 7, the left and right side whetstones
overlap slightly (at their edge portions) in the center between the
two rotary shafts 5 and 6. As a result of this slight overlapping,
the angle of the bottom of a substantially V-shaped grinding groove
formed by the whetstones on both sides becomes smaller, and the
cutting edge is sharply ground.
[0058] FIG. 9 shows the whetstones before mounted on the rotary
shafts.
[0059] The whetstones 7 and 8 are not directly mounted on the
rotary shaft 5. Instead, the whetstones 7 and 8 are mounted on both
ends of a sleeve 14 that has an expanded in diameter portion at the
center. The rotary shaft 5 is passed through a hole 15 in the
sleeve 14, and the sleeve 14 with the whetstones thereon is
fastened in a specified position of the rotary shaft 5. Another
sleeve 14 with whetstones 9 and 10 thereon is fastened likewise in
a specified position of the other rotary shaft 6. Thus, since the
same sleeves with the whetstones mounted thereon can be
manufactured in large numbers and appropriately fastened to the
rotary shafts, the whetstones can be mounted on the rotary shafts
efficiently.
[0060] In the upper surface of the whetstone box 2, a blade
insertion groove 16 in which the blade of the knife is inserted and
moved or drawn (thus being guided) is formed.
[0061] FIG. 5 shows the inside of the whetstone cover 4,
particularly the construction of the blade insertion groove 16. No
that the bottom of the blade insertion groove 16 is removed for its
the entire length, but bottom portions 17 and 18 are disposed near
both ends of the blade insertion groove 16. In other words, the
blade insertion groove 16 has no bottom in the area between the
bottom portions 17 and 18, thus forming a narrow slit 19.
[0062] The reference numerals 20, 21, 22 and 23 indicate protruding
walls that reach the bottom portions 17 and 18. The first whetstone
7 is positioned in the space 24 which is between the bottom portion
18 and the protruding wall 21, the third whetstone 8 is positioned
in the space 25 between the protruding wall 21 and the protruding
wall 23, the second whetstone 9 is positioned in the space 26
between the protruding wall 20 and the protruding wall 22, and the
fourth whetstone 10 is positioned in the space 27 between the
protruding wall 22 and the bottom portion 17. Thus, since the
circumferential surfaces of the respective whetstones show only
slightly for sufficient enough to grind the knife in the respective
spaces 24, 25, 26 and 27 inside the blade insertion groove 16,
there is no danger that sharpening debris will fly into the
surrounding area during use. The sharpening debris drops into the
interior of the whetstone box 2 from the respective spaces. The
sharpening debris inside the whetstone box 2 can be discharged from
a discharge hole 39 (see FIG. 3).
[0063] On the bottom surface of the whetstone box 2 and on the
upper surface of the sharpener main body 1, an engaging device used
to the secure, in a detachable fashion, the whetstone box 2 on the
sharpener main body 1 is provided.
[0064] As shown in FIG. 1, a recess area 28 used for mounting the
whetstone box 2 is formed on the upper surface of the sharpener
main body 1. This recess area 28 is surrounded on two sides by a
sidewall 29 and an end wall 30. As seen from FIG. 7, the sidewall
29 is curved so that this wall opens toward the left as it runs
downward in FIG. 7. One side surface 31 of the whetstone box 2 is
likewise curved so as to conform to the curvature of this sidewall
29. Accordingly, the sidewall 29 of the sharpener main body 1 and
the side surface 31 of the whetstone box 2 make a tight contact
with each other, and the end wall 30 of the sharpener main body 1
and the end surface 32 of the whetstone box 2 make a tight contact
with each other, so that the whetstone box 2 is securely fitted to
the sharpener main body 1, and rattling of the whetstone box 2
never occur during use.
[0065] A guide groove 34 is formed in the bottom surface 33 near
the outside portion of the recess area 28. Furthermore, another
(second) guide groove (not shown) is also formed so as to face the
guide groove 34 so that the sidewall 29 is the bottom of this
groove. This (second) facing guide groove is formed by integrally
forming an L-shaped part on the sidewall 29. As seen from FIG. 4,
projections 35 that engage with the guide groove 34 and the
(second) guide groove that faces this guide groove 34 are formed in
the bottom surface of the whetstone box 2. When the projections 35
are to be engaged with the guide grooves, the engagement is
accomplished by opening the space between the end wall 30 and the
end surface 32 of the whetstone box, applying the side surface 31
of the whetstone box to the sidewall 29, and then pressing the
whetstone box 2 in this state until the whetstone box 2 contacts
the end wall 30.
[0066] A pair of engaging grooves 37 are, as shown in FIG. 1,
formed in the bottom surface of the recess area 28 near the front
surface 36. Furthermore, as shown in FIG. 4, engaging projections
38 that engage with these engaging grooves 37 are provided in the
whetstone box 2. When the whetstone box 2 is attached to the
sharpener main body 1, the engaging projections 38 engage with the
engaging grooves 37 so that the whetstone box 2 is firmly fastened
to the sharpener main body 1.
[0067] The reference numeral 40 in FIG. 1 is a stopper that
prevents the mounted whetstone box 2 from moving toward the front
side (toward the front surface 36) of the main body 1 and coming
loose. The stopper 40 is elastically supported so as to emerge or
sink and is attached to the sharpener main body 1 together with the
stopper device 41 shown in FIG. 11.
[0068] The reference numeral 42 in FIG. 11 is an anchoring
projection that fastens the stopper device 41 to the sharpener main
body 1 (another anchoring projection 42 is also disposed on the
opposite side (not shown in FIG. 11). The stopper 40 is formed as
an integral unit with a knob 43, and a portion between these two
portions is elastically supported by a coil spring 44.
[0069] With the structure above, when the knob 43 is pressed
downward, it is elastically lowered together with the stopper 40,
so that the stopper 40 sinks into the interior of the sharpener
main body 1. The upper surface of the stopper 40 has an inclined
surface. Accordingly, when the whetstone box 2 is mounted on the
sharpener main body 1, the anchoring wall 45 (see FIG. 4) formed on
the bottom surface of the whetstone box 2 contacts the inclined
surface of the stopper 40 and presses the stopper 40 downward so
that the stopper 40 sinks into the interior of the sharpener main
body before the whetstone box 2 contacts the end wall 30.
[0070] When the whetstone box 2 is moved in this state toward the
end wall 30 so that the whetstone box 2 contacts the end wall 30,
the stopper 40 elastically protrudes into the interior of an
anchoring recess 46 of the whetstone box 2. The protruding stopper
40 contacts the anchoring wall 45 and prevents the whetstone box 2
from moving. When the whetstone box 2 is to be detached from the
sharpener main body 1, the knob 43 is pressed down so that the
stopper 40 is caused to sink as described above.
[0071] A motor (not shown in the drawings) is installed in the
housing 47 of the sharpener main body 1, and the motive force of
this motor is transmitted to the rotary shafts by separable spline
shaft couplings via various motive force transmission devices.
[0072] In the shown embodiment, as seen from FIG. 3, spline shaft
coupling insertion bodies 48 are attached to the ends of the rotary
shafts 5 and 6 on a motive force transmission side of the whetstone
box 2. The insertion bodies 48 are respectively provided with
integrally formed four teeth 49 so that the insertion bodies are in
a cruciform shape. As shown in FIG. 2, tubular bodies 50 that are
to be connected to these insertion bodies 48 are provided in the
sharpener main body 1, and four grooves 51 are, as seen from FIGS.
10A and 10B, formed inside each one of the tubular bodies 50 so
that a cruciform shape is formed. As seen from FIGS. 10A and 10B,
the inside surfaces of the respective grooves 51 are, near the
insertion openings 52, formed into tapered surfaces 53 along with
the inside surfaces of the adjacent grooves. Accordingly, since the
insertion openings 52 of the respective grooves are formed so that
these openings are widened toward outside, the insertion bodies 48
of the whetstone box 2 can be smoothly inserted into the tubular
bodies 50. The attachment of the whetstone box 2 to the sharpener
main body 1 is thus facilitated. Furthermore, since the
above-described spline shaft couplings are of the type in which the
teeth 49 of the insertion bodies 48 are inserted into four grooves
51 that are in a cruciform shape, almost no rattling occurs in the
joint portions, and vibration are prevented.
[0073] A guide groove 55 is, as seen from FIG. 1, formed in the
upper surface 54 of the sharpener main body 1. This guide groove 55
communicates with the blade insertion groove 16 of the whetstone
box 2 when the whetstone box 2 is set on the sharpener main body 1.
As seen from FIG. 12, the length of the guide groove 55
substantially extends when it communicates with the blade insertion
groove 16 of the whetstone box 2, the knife is stabilized when the
blade of the knife is inserted into this long groove.
[0074] As seen from FIG. 12, the guide groove 55 is formed so as to
be wider than the width of the blade insertion groove 16 of the
whetstone box 2. The vertical cross section of the guide groove 55
is, however, not symmetrical about its center. In other words, the
right side inside surface of the guide groove 55 is slanted more
than the other side as seen from FIG. 12. Accordingly, the inside
surface on the left side is flush to the inside surface of the
blade insertion groove 16 of the whetstone box 2.
[0075] Furthermore, the upper surface 54 is formed with a step 56
on the right side of the guide groove 55 in FIG. 1. The height of
the upper surface 54 on the front surface 36 side of the step 56 is
the same, but the upper surface 54 closer to the back surface
(opposite from the front surface 36) is formed lower than the step
56. As a result, when the blade of the knife is inserted into the
guide groove 55, the cutting edge of the knife is drawn near side
(toward the front surface 36) while being applied to the upper
surface 54 on the right side; and when the heel portion of the
blade of the knife that is near the handle of the knife comes to
contact the step 56, the knife is moved "as is" to the left (in
FIG. 1); as a result, the blade naturally comes into the guide
groove 55, so that the blade is easily inserted into the guide
groove 55. Since one (left side in FIG. 1) inside surface of the
blade insertion groove 16 and one (left side in FIG. 1) inside
surface of the guide groove 55 are flush to each other, the blade
of the knife can easily come into the narrow blade insertion groove
16 when the blade contacts these inside surfaces and draw the knife
toward the front, i.e., toward the front surface 36 in the
direction of arrow in FIG. 1. Thus, the blade of the knife is
ground when moved or drawn into the blade insertion groove 16 from
the guide groove 55. Since the guide groove 55 and blade insertion
groove 16 are located between the spline shaft couplings, the
overall height of the sharpener can be reduced.
[0076] Though the step 56 is provided at the front edge of the top
surface 54 of the main body 1 as shown in FIGS. 1 and 6 in the
above embodiment, the step 56 can be formed in a position that is
further back from the front edge of the top surface 54 as shown in
FIGS. 7, 12 and 15.
[0077] Next, the construction that transmits the motive force from
the motor to the rotary shafts 5 and 6 will be described.
[0078] FIG. 13 shows the interior of the sharpener main body and
the whetstone box attached to the sharpener main body. The motor is
not shown in FIG. 3, but it is attached to the bottom of the
sharpener main body directly beneath the whetstones 7, 8, 9 and
10.
[0079] As will be described in detail below, a belt transmission
mechanism is employed for transmitting the motive force of the
motor, and a space that includes the motor and rotary shafts 5 and
6 inside the sharpener main body 1 and a space that includes the
belt transmission mechanism are separated by a bearing plate
57.
[0080] The power shaft 58 connected to the motor extends parallel
to the rotary shaft 5 and 6, and a power gear 59 is attached to the
end of this power shaft 58. As shown in FIG. 14, the shaft hole 66
in the power gear 59 has a substantially circular shape having a
flat surface inside, and the power shaft 58 has the same outer
circumferential shape, so that rotation of the power shaft 58 is
securely transmitted to the power gear 59.
[0081] A first gear 60 and a second gear 61 which are larger than
the power gear 59 in diameter are provided side by side above the
power gear 59. The power shaft 58 and the first and second gears 60
and 61 are anchored on the bearing plate 57. The first gear 60 is
provided together with a coaxial lower pulley 62 that rotates as a
unit with this gear 60, and the second gear 61 is provided together
with a coaxial lower pulley 63 that rotates as a unit with this
gear 61. The power shaft 59 engages with the first gear 60, and the
second gear 61 engages with the first gear 60. Thus, the motive
force of the power gear 59 is first transmitted to the first gear
60 and to the second gear 61.
[0082] Two upper pulleys 64 and 65 are attached and supported on
the bearing plate 57 in positions close to the upper end of the
sharpener main body 1. As shown in FIG. 14, two projections 68 are
formed on the pulley shaft 67 of the upper pulley 65, and recessed
portions 69 into which these projections 68 are fitted are formed
in the shaft hole of the upper pulley 65. As a result of this
structure, the rotation of the upper pulley 65 is securely
transmitted to the pulley shaft 67. The other pulley 64 is in the
same configuration as the pulley 65.
[0083] A transmission belt 70 is mounted between the lower pulley
62 and the upper pulley 64, and another transmission belt 71 is
mounted between the lower pulley 63 and the upper pulley 65, so
that the motive force is transmitted.
[0084] The above-described tubular body 50 of one of the spline
couplings is attached to the end of the pulley shaft 67. This
tubular body 50 and the insertion body 48 of the corresponding
rotary shaft 5 are connected via a round hole (not shown) formed in
the end wall 30 so that the rotary shaft 5 is rotated, and the
first whetstone 7 and third whetstone 8 are rotated as a unit with
the rotary shaft 5. The adjacent upper pulley 64, rotary shaft 6,
second whetstone 9 and fourth whetstone 10 are also rotated in the
same manner as described above.
[0085] The two rotary shafts 5 and 6 in this construction are
rotated in opposite directions, so that the whetstones are rotated
in such a direction that the whetstones rub upward over the cutting
edge of the knife. The present invention is, however, not limited
to this construction, and it goes without saying that the rotary
shafts can be rotated in the same direction by way of using a means
of additional gears interposed.
[0086] As seen from FIG. 13, there is a space between the two upper
pulleys 64 and 65, and a groove 72 is formed in the center of the
upper end of the bearing plate 57. Since the guide groove 55 is set
in this space and groove 72, the overall height of the sharpener
can be reduced.
[0087] Next, a grip section 73 that is used to secure the sharpener
in place during use will be described.
[0088] As shown in FIG. 12, the sharpener is set so that the front
surface 36 is positioned in front (or near side or in front of the
user), and the grip section 73 is held by the left hand of a user
so that the grip section 73 is covered by the left hand. As shown
in FIG. 15, the side surface 75 of the grip section is slightly
rounded and is thus formed so that this surface fits the palm of
the hand. Furthermore, a concave end surface 74 is formed in the
back of the grip section 73. When the grip section 73 is held by
being covered by the hand, the fingertips of the user that protrude
from the grip section 73 are bent and applied to the concave end
surface 74 so that the sharpener can be held in place. In this
case, the thumb is naturally on the upper surface of the grip
section 73, and the switch 76 can be operated by slight extension
of the thumb. Thus, the operation can be done easily. The grip
section 73 protrudes to the side of the sharpener and is formed as
a part of the housing 47.
[0089] The motor and electrical devices other than an electrical
cord connected to this motor are provided inside the grip section
73. The motor employed is, for instance, an alternating-current
motor, and thus a plug and an electrical cord that is connected to
the plug are accommodated inside the grip section 73. In a case
that the motor is a direct-current motor, then a dry cell is
accommodated inside the grip section 73. The mechanism of the
switch 76 is also provided in the grip section 73.
[0090] FIG. 16 shows the bottom of the sharpener.
[0091] A cover 77 for the electrical cord storage portion is
attached, and a groove 78 that allows the passage of the electrical
cord during use is formed. Pawls 79 are integrally formed in the
groove 78, so that the cord is held in position in the groove 78 by
the pawls 79, and the sharpener is prevented from being lifted
upward by the cord. Ventilation slits 80 are formed in the bottom
of the sharpener. Heat from the motor escapes through the slits 80.
Ventilation windows 81 are formed near the cover 77. Either the
ventilation slits 80 or the ventilation windows 81 act to suck in
the outside air, while the other acts to discharge heated air.
Accordingly, the air inside the sharpener flows in a convection
current, so that the cooling effect is heightened.
[0092] As shown in FIGS. 17 and 18, a cover 3 can be attached to
the upper surface of the sharpener so as to cover other than the
grip section 73. Since the peripheral edge portion 83 (see FIG. 12)
of the upper surface 54 of the sharpener main body 1 and the
peripheral edge portion 84 of the whetstone box 2 are continuous as
shown in FIG. 12, the cover 3 snugly covers the upper surface 54
and the whetstone box 2.
[0093] FIG. 19 shows a cutting tool sharpener formed with a heel
end receiving section 85 which has a larger width than the blade
insertion groove 16 and is formed continuously at the end of the
blade insertion groove 16. The end portions of the rotary shafts 5
and 6 (not shown in FIG. 19) are located on both sides of the heel
end receiving section 85. This sharpener shown in FIG. 19
efficiently sharpens a knife 87 that has, as seen from FIG. 20, a
thick portion at the heel end 86 of the blade 88. Knives having
thick heel ends are mostly forged knives.
[0094] In the sharpener of FIG. 19, when the thick heel end 86 of
the knife 87 is set in the heel end receiving section 85, the edge
of the blade 88 in front of the heel end 86 is located near the
whetstones that are inside the blade insertion groove 16; as a
result, the edge of the blade 88 can be ground up to the heel end
86.
[0095] The sharpener shown in FIG. 19 is a motor-operated type as
describe above, but it can be a manual sharpener that is not
operated by an electric motor.
[0096] In the sharpener shown in FIG. 19, the heel end receiving
section 85 is formed in the whetstone box 2; however, the sharpener
of the present invention is not limited to one that has a whetstone
box and is applicable to a sharpener that has no whetstone box.
[0097] In use, the blade 88 of the knife 87 is inserted in the
blade insertion groove 16 with the heel end 86 positioned within
the heel end receiving groove 85, and the knife 87 is drawn in the
direction shown by arrow in FIG. 19. When the knife is thus drawn,
the edge of the blade 88 is ground by the whetstones mounted on the
rotary shafts 5 and 6 (not shown) under the whetstone box 2.
[0098] The sharpener in FIG. 19 can be designed so that the
whetstone box 2 is 69.5 mm long, and the entire length of the blade
insertion groove 16 is, including the heel end receiving section
85, 67.5 mm, the heel end receiving section 85 being 16.5 mm long
and its largest width being 17 mm.
[0099] As seen from the above, in the present invention, two
separate rotary shafts are provided, at least one whetstone is
mounted on each of these rotary shafts, the circumferential
surfaces of the whetstones form the grinding surfaces, and the
whetstone on one rotary shaft and the whetstone on the other rotary
shaft are shifted in the axial direction. Accordingly, both sides
of the blade of a cutting tool are simultaneously sharpened, and
burrs are not created on only one surface of the blade.
Consequently, there is no need for re-grinding the opposite surface
of the blade to remove burrs, and the cutting tool is sharpened by
a one-stroke operation.
[0100] In the present invention, the whetstone on one rotary shaft
and the whetstone on the other rotary shaft partially overlap (at
edges) between the two rotary shafts. Accordingly, when the cutting
edge of a cutting tool is set between the whetstones and sharpened,
the cutting edge is ground while being supported on the
circumferential surfaces of the whetstones on both sides, without
passing between the whetstones and slipping out below. As a result,
grinding is performed easily.
[0101] In the present invention, the whetstones have a cylindrical
shape, and the grinding surfaces are at right angles with respect
to the planar or flat portions of the whetstones. Accordingly, the
blade is sharpened using substantially the entire circumferential
surfaces of the whetstones, and sharpening work is performed
efficiently.
[0102] In the present invention, the whetstone on at least one of
the rotary shafts is a truncated cone shape, and this whetstone is
provided so that the smaller diameter side of this cone shape
whetstone faces in the direction in which the cutting tool is moved
during the grinding process. This means that when a cutting tool is
ground by the rotating whetstones while being moved, since the
diameter of the initial whetstone that grinds the cutting edge is
large, the cutting edge is ground extremely sharply, so that the
cutting edge angle becomes smaller; however, as the diameter of the
whetstone gradually decreases in the direction in which the cutting
tool is moved to be ground, the cutting edge angle gradually shows
an increased variation. In other words, the sharpness is somewhat
reduced. If the cutting edge of a cutting tool is formed too
sharply, the strength of the cutting edge tends to decrease, so
that nicks are formed in the blade and so that the cutting edge is
bent. Accordingly, the strength of the cutting edge can be
maintained by the above structure of the present invention.
[0103] In the present invention, the corners that are between the
planar portions and grinding surfaces of the whetstones and face
the direction in which the cutting tool are moved to be ground
during the grinding process of the cutting tool are beveled or have
slant surfaces. Accordingly, it is possible to avoid a situation in
which the movement of the blade of the cutting tool is obstructed
when heel portion of the blade contacts the whetstones during the
movement of the cutting tool.
[0104] Furthermore, in the present invention, when two whetstones
are mounted on each rotary shaft, grinding is performed by four
whetstones. Thus, the sharpening work is performed efficiently.
Since there are two or more whetstones on each side of the blade of
a cutting tool, the blade is stably supported during grinding, and
the sharpening work is smoothly performed.
[0105] The whetstones that are lined up in the direction in which
the cutting tool is moved during grinding are provided so that the
whetstones on the downstream side of the movement for grinding of
the cutting tool has finer grinding surfaces so as to grind the
cutting edge of the cutting tool smoother than the whetstones on
the upstream side of the grinding movement of the cutting tool.
Accordingly, when the cutting edge is sharpened, rough sharpening
is performed first, and then sharpening to a finished surface is
performed afterward. Consequently, one-stroke grinding is
efficiently performed, and the sharpened surface that is finally
sharpened is finished to a smoother finished surface.
[0106] Furthermore, the two or more whetstones on the same rotary
shaft are provided so that the whetstone on the downstream side of
the movement for grinding of the cutting tool has a finer grinding
surface so as to grind the cutting edge of the cutting tool
smoother than the whetstone on the upstream side of the grinding
movement of the cutting tool. With this arrangement, the initial
sharpening and finishing sharpening of both surfaces of the blade
of the cutting tool are respectively performed by whetstones with
the same rough surfaces and the same finishing surfaces on both
sides, it is thus possible to grind the cutting edge of the cutting
tool into the same degree of grinding or sharpness on both surfaces
of the cutting edge.
[0107] In the present invention, sleeve elements on which the
whetstones are mounted are provided on the respective rotary
shafts, and these two sleeve elements have the same configuration
including the whetstones. Accordingly, sleeve elements that have
the whetstones and have the same configuration are respectively
provided on both rotary shafts with these sleeve elements being
shifted in the axial direction. With this structure, there is no
need for work to mount a plurality of whetstones on the rotary
shafts one at a time with certain gaps between these whetstones,
and the whetstones can be mounted on the rotary shafts merely by
attaching the sleeve elements to the rotary shafts. Accordingly,
the work required for assembling the sharpener is reduced.
[0108] Furthermore, in the present invention, the grinding surfaces
of the whetstones on the rotary shafts are rotated in a direction
so as to rub the blade of a cutting tool upward during grinding.
This means that the two rotary shafts rotate in mutually opposite
directions. In other words, the rotation of the whetstones in the
direction in which the whetstones rub upward along the cutting tool
is an equivalent to sharpening performed while the cutting tool is
moved in the direction of the cutting edge with respect to the
sharpening surfaces. Accordingly, no burrs are formed in the
cutting edge, and a cutting edge that has both sharpness and
strength can be obtained.
[0109] In addition, since the rotary shafts are rotated in the same
direction, both surfaces of the blade are ground in opposite
directions. This structure is more effective when grinding that
produces an especially sharp cutting edge is performed.
[0110] Furthermore, with the use of an alternating-current motor, a
strong motive force can be obtained.
[0111] In addition, in the present invention, the heel end
receiving section is provided at the end of the blade insertion
groove so as to be wider than the blade insertion groove.
Accordingly, a cutting tool that has a thick portion in the blade
is sharpened up to such a thick portion. In addition, since the
heel end receiving section is provided in an area where the handle
of a cutting tool that is sharpened is positioned, a cutting tool
that has a thick portion in the blade can be efficiently sharpened
up to such thick portion.
* * * * *