U.S. patent application number 13/463642 was filed with the patent office on 2013-11-07 for blade sharpener.
This patent application is currently assigned to Kabushiki Kaisha Suehiro. The applicant listed for this patent is Tom Hiroshi Hasegawa. Invention is credited to Tom Hiroshi Hasegawa.
Application Number | 20130295823 13/463642 |
Document ID | / |
Family ID | 49512850 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130295823 |
Kind Code |
A1 |
Hasegawa; Tom Hiroshi |
November 7, 2013 |
Blade Sharpener
Abstract
A blade sharpener including a frame casing body having a grip
and a grinding chamber and a grinder assembly detachably installed
in the grinding chamber in which the grinder assembly is formed by
a grinder casing body having a pair of vertical walls facing each
other, a supporting window provided in each of the vertical walls,
a rotary shaft provided between the vertical end walls with both
end thereof in the supporting windows of the vertical walls, an
abrasive wheel provided on the rotary shaft at the axial center,
and a pair of lateral coil springs each provided on either side of
the abrasive wheel. The rotary shaft can be supported by a pair of
longitudinal coil springs installed in the vertical walls.
Inventors: |
Hasegawa; Tom Hiroshi;
(Gardena, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hasegawa; Tom Hiroshi |
Gardena |
CA |
US |
|
|
Assignee: |
Kabushiki Kaisha Suehiro
Niigata-shi
CA
Hasegawa; Tom Hiroshi
Gardena
|
Family ID: |
49512850 |
Appl. No.: |
13/463642 |
Filed: |
May 3, 2012 |
Current U.S.
Class: |
451/194 |
Current CPC
Class: |
B24D 15/082
20130101 |
Class at
Publication: |
451/194 |
International
Class: |
B24B 3/36 20060101
B24B003/36 |
Claims
1. A blade sharpener comprising: a frame casing body having a
grinding chamber; and a grinder assembly detachably installed in
the grinding chamber, said grinder assembly being comprised of: a
grinder casing body having a pair of vertical walls facing each
other, a supporting window provided in each of said pair of
vertical walls, a rotary shaft provided between said pair of
vertical walls with both end thereof in said supporting windows of
said vertical walls, a grinding element provided on said rotary
shaft at substantially an axial center thereof, and a pair of
horizontally urging means each provided on either side of said
grinding element.
2. A blade sharpener comprising: a frame casing body having a
grinding chamber; and a grinder assembly detachably installed in
the grinding chamber, said grinder assembly being comprised of: a
grinder casing body having a pair of vertical walls facing each
other, a supporting window provided in each of said pair of
vertical walls, a vertically urging means provided in each of said
vertical walls, a rotary shaft provided between said pair of
vertical walls with both end thereof in said supporting windows of
said vertical walls and on said vertically urging means, a grinding
element provided on said rotary shaft at substantially an axial
center thereof, and a pair of horizontally urging means each
provided on either side of said grinding element.
3. The blade sharpener according to claim 1, wherein said grinding
element is in substantially a cylindrical shape with a V-groove at
an axial center thereof.
4. The blade sharpener according to claim 2, wherein said grinding
element is in substantially a cylindrical shape with a V-groove at
an axial center thereof.
5. The blade sharpener according to claim 1, wherein said grinding
chamber is covered by a cover casing formed therein with a blade
guide slit and said grinder assembly is disposed under said blade
guide slit so that the rotary shaft of the grinder assembly is set
to be at a biased angle with respect to a length direction of the
blade guide slit.
6. The blade sharpener according to claim 2, wherein said grinding
chamber is covered by a cover casing formed therein with a blade
guide slit and said grinder assembly is disposed under said blade
guide slit so that the rotary shaft of the grinder assembly is set
to be at a biased angle with respect to a length direction of the
blade guide slit.
7. The blade sharpener according to claim 3, wherein said grinding
element is formed by a pair of beveled disks of different diameters
so that smaller diameter sides of said pair of abrasive wheels of
different diameters are connected to each other to form the
V-groove.
8. The blade sharpener according to claim 4, wherein said grinding
element is formed by a pair of beveled disks of different diameters
so that smaller diameter sides of said pair of abrasive wheels of
different diameters are connected to each other to form the
V-groove.
9. The blade sharpener according to claim 1, wherein each of said
horizontally urging means is a coil spring.
10. The blade sharpener according to claim 2, wherein each of said
horizontally urging means is a coil spring.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a blade sharpener that
sharpens blades such as kitchen knives and table knives with an
abrasive wheel and more particularly to a manual blade sharpener
having an abrasive wheel therein.
[0003] 2. Background Art
[0004] Japanese Patent Application Laid-Open (Kokai) No. S62-181860
discloses a table knife sharpener that is comprised of a frame
casing body, a adhesive wheel rotatably installed in this frame
casing body and equipped with grinding surfaces that are of a
truncated cone shape and forming an angle to each other, a guide
part that guides the blade so that the blade being sharpened is
pressed against both grinding surfaces, and a liquid vessel
installed in the frame casing body so as to surround the bottom
part of the abrasive wheel.
[0005] In this device, two sides of the blade of a knife is pressed
against the two sides of the grindstone and the knife is moved back
and forth at a bias relative to the axial direction of the abrasive
wheel that has truncated conical grinding surfaces to sharpen both
sides of the blade. This device has problems, however. During
sharpening by the back and forth movements of the blade, frictional
heat is generated, thus dulling the blade. Grinding dust from the
blade would clog the pores of the abrasive wheel. Though the liquid
vessel that contains liquid for cooling and cleaning the blade
during the sharpening is provided, the problems of the frictional
heat and clogging are not sufficiently solved. Furthermore, since
the abrasive wheel is fixedly provided in the frame casing body, it
is difficult to wash and clean the abrasive wheel.
[0006] Japanese Utility Model Registration No 3007312 discloses a
blade sharpener that is to solve the problems above. This blade
sharpener includes a frame casing body having a grip and a grinding
chamber, a rotary shaft rotatably installed across the grinding
chamber and arranged at a bias to the direction of the length of
the frame casing body, an abrasive wheel that is installed in the
center of the rotary shaft and has grinding surfaces which are
truncated cones and form an angle to each other, a guide part that
guides the blade so that the blade being sharpened is pressed
against the two grinding surfaces, and a liquid vessel installed in
the grinding chamber so that the liquid therein for cooling the
abrasive wheel can surround the bottom part of the abrasive wheel.
Also, Japanese Utility Model Registration No 3010973 discloses a
sharpener for a single-blade knife in which a grinding element is
comprised of a pair of roller bodies having conical surfaces and
one of the conical surfaces is a grinding surface and the other
conical surface is a smooth, hard, non-grinding surface.
[0007] In these blade sharpeners described above, the side of a
blade is, while being pressed against the grinding surface,
sharpened by moving the blade back and forth along the guide part
while it is being pressed against the conical surface of an
abrasive wheel. Accordingly, sharpened conditions of blades can
differ depending on how (in terms of pressing loads, pressing
angles, etc.) the blade is pressed against the abrasive wheel.
Pressing the blade too firmly will create defects in the cutting
edge and can leave it to be able to cut less than before. In
addition, blades with serrated cutting edges and fine ceramic
blades cannot be sharpened very well even with use of a diamond
abrasive wheel for the grinding surface.
[0008] Japanese Utility Model Registration No 3128435 discloses a
blade sharpener that is to overcome the problems described above,
and in this sharpener a rotary shaft that has a abrasive wheel is
supported at both end thereof by a pair of vertically installed
springs so that the blade can be evenly pressed against the
abrasive wheel and evenly grinded by the conical surfaces of the
abrasive wheel.
SUMMARY OF THE INVENTION
[0009] Accordingly, the present invention is made with the above
problems in mind, and it is an object of the present invention to
provide a blade sharpener that is able to prevent variations in the
force of pressing the cutting edge against conical surfaces of an
abrasive wheel and can grind blades further evenly and smoothly
compared to the existing blades sharpeners such as those described
above.
[0010] The above object is accomplished by a unique structure of
the present invention for a blade sharpener that comprises: [0011]
a frame casing body having a grip and a grinding chamber; and
[0012] a grinder assembly which is detachably installed in the
grinding chamber and comprised of: [0013] an empty substantially
rectangular block shape grinder casing body having a pair of
vertical walls facing each other, [0014] a supporting window
provided in each of the vertical walls, [0015] a rotary shaft
provided between the vertical walls with both end thereof in the
supporting windows of the vertical walls, [0016] a grinding element
provided on the rotary shaft at substantially an axial center
thereof, and [0017] a pair of horizontally urging means each
provided on either side of the grinding element.
[0018] Furthermore, the above objects are accomplished by another
unique structure of the present invention for a blade sharpener
that comprises: [0019] a frame casing body having a grip and a
grinding chamber; and [0020] a grinder assembly which is detachably
installed in the grinding chamber and comprised of: [0021] an empty
substantially rectangular block shape grinder casing body having a
pair of vertical walls facing each other, [0022] a supporting
window provided in each of the vertical walls, [0023] a vertically
urging means provided in each of the vertical walls, [0024] a
rotary shaft provided between the vertical walls with both end
thereof in the supporting windows of the vertical walls and on the
vertically urging means, [0025] a grinding element provided on the
rotary shaft at substantially an axial center thereof, and [0026] a
pair of horizontally urging means each provided on either side of
the grinding element.
[0027] In the structures of the present invention as describe
above, since the grinding element of the blade sharpener is
constantly urged by the two lateral urging means or coil springs so
that the grinding element is at the middle of the distance between
the two vertical walls during the grinding process, the blade being
grinded receives lateral pressure (or pressing force) from both
sides by the urging means and makes good contact with the grinding
element when the blade is moved back and forth with respect to the
grinding element and as a result is sharpened smoothly and
efficiently. Furthermore, in the structure that further, includes
the vertical coil springs, the blade that is receiving downward
pressing force against the grinding element by the user further
receives upward pressing force caused by the vertical coil springs
that is in the direction opposite from the downward pressing force,
in addition to the lateral pressure by the lateral urging means (or
coil springs). Accordingly, the blade receives not only the lateral
pressure but also the longitudinal pressure (or pressing force)
from four directions and thus can make further good contact with
the grinding element when the blade is moved back and forth with
respect to the grinding element, and the blade is thus sharpened
further smoothly and efficiently.
[0028] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0029] FIG. 1 shows a front view of a frame casing body of the
blade sharpener according to the present invention;
[0030] FIG. 2 is a top view thereof with the cover casing of the
frame casing body removed;
[0031] FIG. 3A is an enlarged side view of holding means and FIG.
3B is an enlarged top plan view thereof;
[0032] FIG. 4A is a vertically cross-sectional view of first type
of grinder assembly according to the present invention with a
symmetric abrasive wheel employed, and FIG. 4B is a side view
thereof;
[0033] FIG. 5 illustrates an arrangement of grinder assemblies
installed in the grinding chamber of the blade sharpener of the
present invention;
[0034] FIG. 6 is a vertically cross-sectional view of the first
type of grinder assembly according to the present invention with an
asymmetric abrasive wheel is employed;
[0035] FIG. 7 illustrates the grinder assembly of FIG. 4A with the
abrasive wheel depressed down during grinding;
[0036] FIG. 8A is a vertically cross-sectional view of another type
of grinder assembly according to the present invention with a
symmetric abrasive wheel employed, and FIG. 8B is a side view
thereof;
[0037] FIG. 9 is a vertically cross-sectional view of the other
type of grinder assembly according to the present invention with an
asymmetric abrasive wheel is employed;
[0038] FIG. 10 is a top view of a frame casing body of a blade
sharpener in which the cover casing is formed with one single blade
slit so that a single grinder assembly is installed in the grinding
chamber;
[0039] FIG. 11 illustrates the cross-section of a known
double-edged blade; and
[0040] FIG. 12 illustrates the cross-section of a known
single-edged blade.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Preferred embodiments of a blade sharpener according to the
present invention will be described in detail below with reference
to the accompanying drawings.
[0042] FIGS. 1 and 2 illustrate an example of a frame casing body 1
of the blade sharpener according to the present invention. The
frame casing body 1 is made of, for instance, synthetic resin and
includes a grip 2 and a grinding chamber 3 which is connected to
the end of the grip 2 and is substantially in a rectangular box
shape having a size of for instance 2.5 inches (W).times.4 inches
(L).times.2.5 inches (H). The grinding chamber 3 is provided with a
removable cover, casing 4 covering the upper opening of the
grinding chamber 3, and this removable cover casing 4 is formed
with two blade guide slits 5 which extend in the width direction W
of the grinding chamber 3 so as to open continuously to the above
and to both sides of the cover casing 4.
[0043] On the rectangular bottom 3a of the grinding chamber 3, one
pair of (or two) holding means 6 are provided. As seen from FIGS.
3A and 3B, each one of the holding means 6 is comprised of four
projections 6a each of which is in a shape of L when viewed from
above (or through the removable cover casing 4). Four projections
6a form a rectangular shape (when they are connected with dotted
lines, see FIG. 3B) that is substantially the same as (or slightly
smaller than) the bottom of each one of grinder assemblies 10
(described below), so that the grinder assembly 10 is held by the
four projections 6a when the grinder assembly 10 (or the bottom
thereof) is pressed (by hand of a user of the sharpener) against
the rectangular area defined by the four projections 6a from above
so that the four corners of the grinder assembly 10 are
respectively in contact with the four projections 6a that are each
in an L shape when viewed from above as described above. Since the
holding means 6 (or the four projections 6a ) and the grinder
assembly 10 are made of resins or plastics, and the bottom of the
grinder assembly 10 is slightly larger than the area defined by the
four projections 6a, the grinder assembly 10 can be secured tightly
in position by the holding means 6 and nonetheless can be separated
therefrom when the grinder assembly 10 is forcedly lifted (by
hand). The grinder assembly 10 is thus removed from the grinding
chamber 3 for, for instance, cleaning of the grinder assembly 10
(and the grinding chamber 3) and for replacement thereof.
[0044] Each one of the pair of grinder assemblies 10 that are
detachably installed in the grinding chamber 3 of the frame casing
body 1 as described above (they can thus be called grinder
cassettes in view of the removability) comprises as shown in FIGS.
4A and 4B a grinder casing body 10A formed by a rectangular bottom
plate 12, a pair of end walls 14 vertically formed along the two
shorter side edges of the rectangular bottom plate 12 so as to face
each other, and a pair of side walls 16 formed along two longer
side edges of the rectangular bottom plate 12 to face each other
(The side walls 16 are lower than the end walls 14 so as to allow a
blade, an abrasive wheel and a rotary shaft to be moved down as
described below). Thus, the frame casing body 1 in this example is
an empty substantially rectangular block shape. In each one of the
pair of (or two) vertical end walls 14 facing each other, a
supporting window 14A is opened, and below this supporting window
14A, a vertical channel 14B is provided. In this vertical channel
14B, a longitudinal coil spring 20, which is greater (longer) than
the depth of the vertical channel 14B, is installed so as to stand
vertically within the vertical channel 14B. Thus, an upper end
portion of the longitudinal coil spring 20 is outside of the
vertical channel 14B to project out therefrom and is located inside
the supporting window 14A. A supporting piece 20A is attached to
the top end of the longitudinal coil spring 20 so that it is in the
supporting window 14A.
[0045] The grinder casing body 10A thus having a pair of
longitudinal coil springs 20 further includes a rotatable shaft 22.
This rotatable shaft 22 is provided inside the grinder casing body
10A horizontally with its both ends inside the supporting windows
14A of the end walls 14 and on the supporting pieces 20A of the
coil springs 20. To the top surface of each one of the end walls 14
of the grinder casing body 10A is attached a holding piece 14C so
as to cover the upper opening of each of the windows 14A and
prevent the rotatable shaft 22 from being removed upwardly from the
supporting windows 14A (or from the end walls 14 of the grinder
assembly 10). The diameter of the rotatable shaft 22 is (slightly)
smaller than the width W' of the supporting window 14A, and the
height H' of the supporting window 14A is greater than the width W'
of the supporting window 14A for the substantially the same amount
(length) as the upper end portion of the longitudinal coil spring
20 projecting out of the vertical channel 14B into the supporting
window 14A. As a result, the rotatable shaft 22 being supported by
the supporting windows 14A is rotatable within the supporting
windows 14A and is movable within the supporting windows 14A
vertically (or up and down) but is restricted from moving in the
direction of the width W' of the supporting window 14A.
[0046] The rotatable shaft 22 is provided thereon with an abrasive
wheel (grinding element) 30, a pair of lateral coil springs 40 (40A
and 40B) on either side of the abrasive wheel 30, and a pair of
washers 50 each on the far end side of each coil spring 40 from the
abrasive wheel 30.
[0047] The abrasive wheel 30 is provided at substantially the
center of the rotatable shaft 22 in the axial direction. The
abrasive wheel 30 is a cylindrical grinding element having a
V-groove 32 in the circumferential surface, so that it has such a
shape that a pair of truncated cone-shaped elements are connected
to each other at the smaller diameter end surfaces so as to form
the V-groove 32 in between or that a pair of oppositely beveled
abrasive disks are connected to each other at the smaller diameter
end surfaces.
[0048] On either side of the abrasive wheel 30, the lateral coil
spring 40 is provided so that one end thereof is in touch with the
abrasive wheel 30 and another end thereof is in touch with the
washer 50 and so that each coil spring 40 is compressed by and
between the abrasive wheel 30 and the washer 50. In other words,
the abrasive wheel 30 is urged by the coil springs 40 towards the
axial center of the rotatable shaft 22 as shown by A-1 and A-2
arrows in FIG. 4A so as to be at the center or at a middle point of
the two vertical end walls 14 of the grinder casing body 10A. The
two lateral coils springs 40 (40A, 40B) have the inner diameter
slightly larger than the diameter of the rotatable shaft 22 so that
they are loosely disposed around the rotatable shaft 22 on both
sides of the abrasive wheel 30. Also, these coil springs 40 (40A,
40B) are substantially the same in length and have substantially
the same spring force with each other. Thus, in FIG. 4A, the coil
spring 40A urges the abrasive wheel 30 into the right direction
shown by arrow A-1, and the coil spring 40B which is on another
side of the abrasive wheel 30 urges the abrasive wheel 30 into the
left direction shown by allow A-2 or in the opposite direction from
the direction the coil spring 40A urges the abrasive wheel 30.
[0049] The washers 50 of a thin plate having an inner diameter
slightly larger than the diameter of the rotatable shaft 22 are
disposed on the rotatable shaft 22, and the outer diameter of the
washers 50 is greater than the size of the supporting windows 14A,
particularly greater than the width W' (see FIG. 4B) of the
supporting window 14A, of the end walls 14 of the grinder casing
body 10A, so that the surface of each of the washers 50 that faces
the end wall 14 is slidably in contact with the inner surface of
the end wall 14.
[0050] The above described pair of grinder assemblies 10 each
comprising the grinder casing body 10A, the horizontal rotatable
shaft 22, the lateral coil springs 40 and the vertical coil springs
20 are installed in the grinding chamber so that they are
respectively directly below the blade guide slits 5 formed in the
cover casing 4 of the grinder casing body 10A and so that the
rotatable shafts 22 and thus the grinding wheels 30 of these two
grinder assemblies 10 are at bias or diagonal with respect to the
length direction L' of the blade guide slits 5 of the frame casing
body 10A. More specifically, as seen from FIG. 2 and FIG. 5, in
which the abrasive wheels 30 are drawn exaggeratingly for easier
understanding, the pair of holding means 6 are provided on the
bottom 3a of the grinding chamber 3 so as to have a bias or
diagonal angle of 10-25 degrees with respect to the length
direction L of the grinding chamber 3, and thus the two grinder
assemblies 10 that are respectively held by these holding means 6
each comprised of four projections 6a are provided so that the
center of the abrasive wheel 30 or the V-groove 32 thereof is at a
bias or diagonal angle of about 10 to 20 degrees with respect to
the length direction L' of the blade guide slits 5 and the rotary
shafts 22 take a symmetric positional relationship with each other
about the center line C of the grinding chamber 3 which is at right
angles to the direction of length L of the grinding chamber 3.
However, the arrangement of the grinder assemblies 10 can take
another manner in which the rotary shafts 22 are parallel to each
other, and a only one (or single) grinder assembly 10 can be
installed in a grinding chamber 3 of which cover casing 4 is formed
only one blade guide slit 5 (or two blade guide slits 5).
[0051] In the above described structure, the abrasive wheel 30 has
a cylindrical shape in which the V-groove 32 is in the axial center
and in such a shape that a pair of two truncated cones (or beveled
disks) of the same diameter are connected to each other at the
smaller diameter end surfaces, thus having a symmetric grinding
surfaces 32A and 32B along the V-groove 32, and thus being called
in the description a "symmetric abrasive wheel." This symmetric
abrasive wheel is suitable to sharpen a double-edged blade X as
shown in FIG. 11 that has the same blade surface XA and XB on both
sides. The abrasive wheel in the present invention can be of
another type as shown in FIG. 6. In this abrasive wheel 30', the
diameters of the two truncated cone elements (or beveled disks) are
different from each other, so that the V-groove 32' is asymmetric
with one grinding surface 32A' has more acute angle than the other
grinding surface 32B', thus being called in the description an
"asymmetric abrasive wheel." In the shown asymmetric abrasive wheel
30', the grinding surface 32A' on the left side is about 5 to 20
degrees with respect to the imaginary vertical line C' and the
grinding surface 32B' on the right side is about 15 to 45 degrees
with respect to the vertical center line C'. This asymmetric
abrasive wheel 30' is suitable to sharpen a single-edged blade Y as
shown in FIG. 12 that has on one side of the blade a single blade
surface YA (the blade Y can be formed with a minute blade surface
YB on another side).
[0052] In use of the above-described blade sharpener, a pair of
grinder assemblies 10 (more specifically, two grinder assemblies
both having symmetric abrasive wheels, or both having asymmetric
abrasive wheels or one having a symmetric abrasive wheel and the
other having an asymmetric wheel) are set in the grinding chamber 3
by being held by the holding means 6, and the grinder assembly or
assemblies 10 are filled with a liquid Lq, such as water or oil,
and the grinding chamber 3 is covered by the cover casing 4.
[0053] With the cover casing 4 thus set and the grip 2 gripped by
one hand, the blade (such as the blade X) of a knife held by
another hand at the handle is inserted into the guide slit 5 and
pressed down against the abrasive wheel 30 so that the cutting edge
of the blade X comes into contact with the V-groove 32 of the
abrasive wheel 30 and then moved back and forth inside the blade
guide slit 5 along its length direction or in the direction of the
width W of the grinding chamber 3. As a result, the blade surfaces
XA and XB contact the grinding surfaces 30A and 30B while being
pressed against thereto, and the blade X is thus sharpened. Since
the blade X is pressed against the abrasive wheel 30, the rotatable
shaft 22 is pressed and moved down within the supporting window 14A
as shown in FIG. 7, and the longitudinal coil springs 20 press back
(upward) the rotary shaft rotatable shaft 22 as indicated by upward
arrows. The blade X thus receives pressing forces from above (by
the user) and from below (by the longitudinal coil springs); and as
a result, it is pressed substantially uniformly against the
grinding surfaces 30A and 30B and thus sharpened evenly and
efficiently.
[0054] In addition to these vertical pressing forces, the blade X
receives lateral or horizontal pressing forces from one side (for
instance, from the left side by the lateral coil spring 40A) and
from another side (for instance, from the right side by the lateral
coil spring 40B) when the blade X is moved back and forth in a
reciprocating manner in the blade guide slit 5. More specifically,
since the rotary shaft 22 is set to have a biased or diagonal angle
relationship (of 10-20 degrees) with respect to the blade guide
slit 5, when the blade X is moved in one direction, one lateral
coil spring (for instance the spring 40A) is compressed and the
other lateral coil spring (for instance spring 40B) expands, and
when the blade X is moved in another or opposite direction, then
the coil spring compressed (spring 40A) expands and the spring
expanded (spring 40B) is compressed. When grinding is thus
performed, these lateral or horizontal pressing forces that are
opposite from each other in direction and are equal to each other
in strength are repeatedly applied to the blade X. As a result, in
addition to the vertical pressing forces by the user and
longitudinal coil springs 20, the blade X repeatedly receives equal
amount of lateral or side pressing forces from the two lateral
springs 40 (40A, 40B) and is pressed sideways substantially
uniformly and repeatedly against the grinding surfaces 30A and 30B
of the abrasive wheel 30. The blade X is, accordingly, sharpened
further evenly, efficiently and smoothly.
[0055] Also, during the back and forth movement of blade X with a
pressing force applied thereto from above, the rotating abrasive
wheel 30 can come in contact with the liquid Lq in the sharpening
assembly 10. This liquid Lq absorbs the heat generated during the
grinding and prevents the blade X from dulling that would be caused
by heat, and it washes away grinding debris and thus maintains the
grinding surfaces 30A and 30B in good grinding condition without
getting clogged.
[0056] When the blade X is pressed against the abrasive wheel 30 as
described above, the pressing back forces of the longitudinal coil
springs 22 make the force of the abrasive wheel 30 applying to the
blade X substantially uniform. As a result, with an addition of the
lateral or horizontal pressing forces by the lateral coil springs
40, grinding of even a serrated edge knife such as bread slicing
knives and fine ceramic blades and the like can be done
efficiently.
[0057] A single-edged blade Y can be grinded in the substantially
the same manner as in the blade X. The blade surface YA is brought
into contact with the grinding surface 30A and blade Y is pressed
down and moved back and forth within the guide slit 5, and the
blade Y is sharpened while receiving the lateral forces from the
lateral coil springs and also receiving the longitudinal forces
from the longitudinal coil springs.
[0058] As seen from the above, according to the present invention,
a blade to be sharpened (including both double-edged blade and
single-edged blade) receives pressing forces of not only in the
vertical direction (or in the up and down directions) but also in
the horizontal direction (or in the right and left directions).
Accordingly, the blade is grinded and sharpened smoothly and
evenly, producing a sharp cutting edge.
[0059] In the above describe structure and operation, the grinder
assembly 10 is provided with a pair of longitudinal coil springs
and a pair of lateral coil springs. However, the object of the
present invention can be accomplished by a structure that includes
only a pair of lateral springs.
[0060] In this aspect of the present invention, as seen from FIGS.
8A and 8B, each one of pair of grinder assemblies 110 that are
detachably installed in the grinding chamber 3 of the frame casing
body 1 (they can thus be called grinder cassettes as well in view
of the removability) comprises a grinder casing body 110A is formed
by a rectangular bottom plate 102, a pair of end walls 104
vertically formed along the two end shorter side edges of the
rectangular bottom plate 102 so as to face each other, and a pair
of side walls 106 formed along two longer side edges of the
rectangular bottom plate 102 to face each other. In each one of the
pair (two) of end walls 104 facing each other, a supporting window
104A is opened.
[0061] In addition, the grinder assembly 110 further includes a
rotatable shaft 122. This rotatable shaft 122 is provided within
the grinder assembly 110 horizontally with its both ends inside the
supporting windows 114A of the end walls 114. To the top surface of
each one of the end walls 114 is attached a holding piece 104C so
as to cover the upper opening of each of the supporting windows
114A and prevent the rotatable shaft 122 from being removed
upwardly from the supporting windows 114A (or from the end walls
114 of the grinder assembly 110). The diameter of the rotatable
shaft 122 is (slightly) smaller than the width W'' and height H''
of the supporting window 114A. As a result, the rotating shaft 122
is rotatable within the supporting windows 114A.
[0062] The rotatable shaft 122 is provided thereon with an abrasive
wheel (grinding element) 130, a pair of lateral coil springs 140
(140A and 140B) on either side of the abrasive wheel 130, and a
pair of washer 150 each on the far end side of each coil spring 140
from the abrasive wheel 130. This structure that includes the
rotatable shaft 122 with the abrasive wheel 130, the lateral coil
springs 140 and the washers 150 thereon and the functions of the
these parts arc the same as those of the structure of the rotatable
shaft 22 having thereon the abrasive wheel 30, the lateral coil
springs 40 and the washers 50 shown in FIGS. 4A and 4B.
[0063] In addition, an asymmetric abrasive wheel 130' as shown in
FIG. 9 can be employed instead of the abrasive wheel 130 shown in
FIG. 8. In this abrasive wheel 130', the diameters of the two
truncated cone elements (or beveled disks) are different from each
other, so that the V-groove 132' is asymmetric with one grinding
surface 132A' has more acute angle than the other grinding surface
132B'. In the shown asymmetric abrasive wheel 130', the grinding
surface 132A' on the left side is about 5 to 20 degrees with
respect to an imaginary vertical line C'' and the grinding surface
132B' on the right side is about 15 to 45 degrees with respect to
the imaginary vertical line C''. This asymmetric abrasive wheel
130' is also suitable to sharpen a single-edged blade Y as shown in
FIG. 12
[0064] The above described pair of grinder assemblies 110 each
including the horizontal rotatable shaft 122 and the lateral coil
springs 140 are installed in the grinding chamber 3 in the same
manner as that of the grinder assemblies 10.
[0065] In use of the above-described blade sharpener, a pair of
grinder assemblies 110 (in other words, two grinder assemblies both
having symmetric abrasive wheel, or both having asymmetric,
abrasive wheels or one having a symmetric abrasive wheel and the
other having an asymmetric wheel) are set in the grinding chamber 3
by being held by the holding means 5. The grinder assemblies can be
filled with a liquid Lq, such as water or oil, and the grinding
chamber 3 is covered by the cover casing 4.
[0066] With the cover casing 4 thus set and the grip 2 gripped by
one hand, the blade X of a knife held by another hand at the handle
is inserted into the guide slit 5 and pressed down against the
abrasive wheel 130 so that the cutting edge XE of the blade X comes
into contact with V-groove 132 of the abrasive wheel 130 and then
moved back and forth inside the blade guide slit 5 along its length
direction or in the direction of the width W of the grinding
chamber 3. As a result, the blade surfaces XA and XB contact the
grinding surfaces 130A and 130B while being pressed against
thereto, and the blade X is thus sharpened.
[0067] More specifically, the blade X receives lateral pressing
forces from one side (for instance from the left side by the
lateral coil spring 140A) and from another side (for instance from
the right side by the lateral coil spring 140B) when the blade X is
moved back and forth in a reciprocating manner in the blade guide
slit 5. In other words, since the rotary shaft 122 is set to have a
biased or diagonal angle relationship (of 10-20 degrees) with
respect to the blade guide slit 5, when the blade X is moved in one
direction, one lateral coil spring (for instance the spring 140A)
is compressed and the other lateral coil spring (for instance
spring 140B) expands, and when the blade X is moved in another or
opposite direction, then the coil spring compressed (spring 140A)
expands and the spring expanded (spring 140B) is compressed. When
grinding is performed, these lateral or horizontal pressing forces
that are opposite from each other in direction and are equal to
each other in strength are repeatedly applied to the blade X. As a
result, the blade X repeatedly receives equal amount of lateral or
side pressing forces from the two lateral springs 140 (140A, 140B)
and is pressed sideways substantially uniformly and repeatedly
against the grinding surfaces 30A and 30B of the abrasive wheel 30.
The blade X is thus sharpened evenly, efficiently and smoothly. The
blade Y as shown in FIG. 12 can be grinded in the same manner as
above with the grinder assembly shown in FIG. 9.
[0068] Thus, according to the above-described structure, since a
blade to be sharpened (including both double-edged blade and
single-edged blade) receives pressing forces in the horizontal
direction (or in the right and left directions), the blade is
grinded and sharpened smoothly and evenly, producing a sharp
cutting edge.
[0069] Though the abrasive wheels 30 and 130 are formed by the same
material entirely, the materials that make the grinding surface 30A
and 130A can be alumina- or silicon-carbide ceramics, and the like,
and the materials that make the grinding surfaces 30B and 130B can
be different substances including silica clay ceramics, or alumina
fine ceramics or alumina new ceramics, forming the surfaces smooth
and hard.
[0070] In the above description, a pair of or two grinder
assemblies are installed in the grinding chamber. However, only one
or a single grinder assembly can be installed in the grinding
chamber, and further, as seen from FIG. 10, the cover casing 4 can
be formed with only one blade guide slit 5 so that a single grinder
assembly 10 (110) is installed in the grinding chamber 3.
[0071] Also, though coil springs are described as an urging means
to place the abrasive wheel to the center of the grinder assembly
and to below the blade guide slit, any other replacement urging
means can be used in the present invention such as a so-called
washer-less-spring that is made of plastic. In addition, a
permanent magnet and/or rubber sheets can be affixed to the
underside of the frame casing body so as to prevent the sharpener
from slipping during the use or grinding.
* * * * *