Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
BLADE-REPLACEABLE CUTTER
BACKGROUND OF THE INVENTION
The present invention relates to a blade-replaceable cutter
for a multi-edged slitter mainly for use to cut and align the
back pasting portion of a book which must be bound in a book binding
process . More particularly, the present invention relates to an
improvement in the shape of a replaceable blade and the cross
sectional shape of the outer portion of the cutter body in a
joining portion of a replaceable blade.
Hitherto, a cutter of the foregoing type has been known which
has a structure, for example, as shown in Figs . 12 and 13 . That
is, a plurality of chip joining seats la are, at the same angular
intervals, formed along the sunk portions on the same
circumference of the outer bevel face of a disc-shape cutter body
1. The chip joining seats 1a are identically inclined at a
predetermined angle in the direction of the rotation of the cutter.
A rectangular plate-like chips 2 made of a hard material for a
cutting edge, such as cemented carbide or high speed tool steel,
are brazed to the side face of the cutter body such that the
rectangular plate-like chips 2 proj ect over the outer periphery
of the cutter body. Moreover, the leading ends of the chips are
sharpend.
As shown in Figs. 14 and 15, a replaceable blade type
structure has been known. That is, a plurality of replaceable
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blade joining seats 5a identically inclined in a direction of
the rotation of the cutter by a predetermined angle are formed
on the same outer circumference of a disc-shape cutter body 5.
Substantially rectangular plate-like replaceable blade chips 6
having joining holes formed previously and edged leading ends
are joined to the cutter body 5 with bolts. Thus, the secured
chips 6 project over the side face of the cutter body 5.
The foregoing conventional cutters incorporating the
cutting edges having leading ends formed into the sharp knife
shapes suffer from a problem in that the cutting edges easily
become chipped. Although a relatively large number of cutting
blades can be provided, the sharp cutting edge and the large number
of the blades cause impactive cutting noise having high
frequencies to easily be produced. Thus, there arises a problem
in that the environment for the cutting operation deteriorates
owning to noise.
The operation for re-grinding the cutting edge is performed
such that the leading end of the cutting edge on the side face
of the cutter body is ground. Therefore, the thickness of the
cutter is changed, that is, reduced whenever the re-grinding
operation is performed. Hence it follows that the cutting
positions with respect to a work which must be ground are changed.
To make coincide the cutting position, fine adjustment of the
positions of the chips must be performed when the cutter is joined
to the finishing machine. The foregoing fine adjustment is an
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operation requiringsignificantskill. Undesirablecollision of
the cutting edge with a pressing roller or the like joined to
the body of the finishing machine to overhang above the cutter
frequently causes chipping of the cutting edge to occur. Hence
it follows that workability excessively deteriorates. What is
worse, cost reduction cannot be realized because of a required
cost for repairing the blade.
SUMMARY OF THE INVENTION
In view of the foregoing, an obj ect of the present invention
is to provide a blade-replaceable cutter which is free from easy
chipping, which permits quick repair if the cutting edge is
chipped, which is able to eliminate cutting noise and which
prevents considerable change in the thickness of the cutter after
re-grinding has been performed.
To achieve the foregoing object, according to one aspect
of the present invention, there is provided a blade-replaceable
cutter, comprising: a disc-shape cutter body having a plurality
of joining seats for replaceable blades formed on the same
circumference in one side surface of an outer portion thereof;
and mechanical means for locating and securing the replaceable
blades to the joining seats, wherein the replaceable blade is
formed into a single side bevel circular knife shape and having
a cutting edge line which can be changed by rotating the
replaceable blade around an axis perpendicular to the joining
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seat, and the replaceable blade is joined in such a manner that
a portion of the leading end of the replaceable blade projects
over the outer periphery of the cutter body, substantially overall
portion of the side face of the replaceable blade which does not
project over the outer periphery of the cutter body does not
proj ect over the side surface of the cutter body in a direction
of the axis of rotation of the cutter and the portion of the leading
end of the replaceable blade proj ecting over the outer periphery
of the cutter body makes a positive radial clearance angle.
According to the present invention, the replaceable blade
formed into the single side bevel circular knife is employed.
Although the number of blades is reduced as compared with that
of the conventional structure, the strength of the cutting edge
can be raised. Thus, chipping of the cutting edge and impactive
and grating cutting noise having high frequencies can be
eliminated. Since the cutting position of the replaceable blade
can be changed, quick repair is permitted if chipping of the
cutting edge occurs. Each replaceable blade can be used many
times and the number of re-grinding can be reduced. Moreover,
the lifetime can be elongated. Since the bevel face of the
replaceable blade is ground in place of grinding of the side face
of the blade, the thickness of the cutter is not substantially
changed when the re-ground replaceable blade has been joined to
the cutter body. Therefore, substantially fine adjustment is not
required and skillfulness is not required when the cutter is
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joined. Therefore, an unskilled worker is able to easily replace
and regrind the blade-replaceable cutter according to the present
invention. The working efficiency is improved.
The leading end of the cutting edge of the replaceable blade
projecting over the outer periphery of the cutter body has the
positive radial clearance angle. Therefore, the overall portion
of the side face of the replaceable blade is not brought into
contact with the cutting surface. Therefore, the sharpness of
the cutting surface does not deteriorate easily. The leading
ends of the cutting edges which do not concern the cutting are
embedded and retracted in the cutter body from the side surface
of the cutter body. Only the portions of the cutting edges
proj ecting over the outer periphery of the cutter body are used
to perform cutting. Therefore, contactbetweenthecuttingedges
which do not concern the cutting operation and cutting dust can
be prevented. Hence it follows that the cutting edges can be
protected. Thus, the sharpness of the cutting edges can always
be maintained.
A structure may be employed in which the shape of the cutting
edge line of the replaceable blade is formed into the circular
shape or the polygonal shape, and the cutting edge is rotated
and indexed by a locating mechanism. As a result, the replaceable
blade in the form of a small chip formed into a single side bevel
circular knife can accurately be rotated and indexed at a
predetermined angle. When the replaceable blade is rotated and
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indexed, one replaceable blade can be used several times . Thus,
the lifetime of each replaceable blade can be elongated. As
described above, contact between the cutting edges which do not
concern the cutting operation and cutting dust can be prevented.
Therefore, the cutting edges are not damaged until the foregoing
cutting edges are used to perform the cutting operation. A
satisfactory sharpness of the cutting edge can be obtained when
the cutting edge has been indexed. Thus, the lifetime can be
stabilized. It leads to a fact that the lifetime of each
replaceable blade can be elongated. Since the position of the
cutting edge is changed if the cutting edge is worn, the cutting
surface does not deteriorate. As a result, the lifetime can be
elongated and the running cost can significantly be reduced.
A structure may be employed in which a portion of the
replaceable blade with which the replaceable blade is joined and
located with respect to the cutter body is formed into a polygonal
cylindrical shape. Thus, the rotation of the replaceable blade
is prevented such that at least two opposite sides of the polygon
are held or two sides of the polygon are received by V-shape
surfaces. When the position of the cutting edge is changed at
the position at which the replaceable blade has been joined,
indexing and location can easily and reliably be performed.
A structure may be employed in which a screw for clamping
the replaceable blade is provided such that pressing force
directed to the central portion of the cutter body acts on the
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replaceable blade after the replaceable blade has been clamped
to the joining seat of the cutter body. As a result, the
countersunk surface of the screw presses the 90°-countersunk
surface of the replaceable blade when the replaceable blade is
clamped with the countersunk head screw for clamping the
replaceable blade. Thus, the fractional pressing force acts on
the central portion of the cutter. Therefore, the side surfaces
of the polygonal cylinder replaceable blade are strongly pressed
against the reference surface of the wall of the joining seat.
Thus, locating and securing can reliably be performed.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side view showing a portion of a cutter body
according to the present invention;
Fig. 2 is an enlarged cross sectional view showing a seat
for joining a replaceable blade of the cutter body in a direction
of the diameter of the cutter;
Fig. 3 is a fragmentary view taken in the direction of the
arrows along line A-A shown in Fig. 1;
Fig. 4 is an enlarged cross sectional view showing a state
in which the replaceable blade has been joined in a direction
of the diameter of the cutter;
Fig. 5 is a fragmentary view taken in the direction of the
arrows along line B-B shown in Fig. l;
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Fig. 6 is a side view showing the side face of the blade
such that the replaceable blade according to the first embodiment
is enlarged;
Fig. 7 is a side view showing a bevel face portion such that
the replaceable blade according to the first embodiment is
enlarged;
Fig. 8 is an enlarged front view showing the replaceable
blade according to the first embodiment;
Fig. 9 is an enlarged vertical cross sectional view showing
the replaceable blade according to the first embodiment;
Fig. 10 is an enlarged side view showing a replaceable blade
according to a second embodiment;
Fig. 11 is an enlarged front view showing the replaceable
blade according to the second embodiment;
Fig. 12 is a side view showing a portion of a conventional
cutter having a structure in which the cutting edges are fixed;
Fig. 13 is a vertical cross sectional view showing a portion
of the conventional cutter having a structure in which the cutting
edges are fixed;
Fig. 14 is side view showing a portion of a conventional
cutter having a structure in which the cutting edges are
replaceable; and
Fig. 15 is a vertical cross sectional view showing a portion
of a conventional cutter having a structure in which the cutting
edges are replaceable.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will now be described
with reference to Figs. 1 to 5 which show a portion of the cutter
body and Figs. 6 to 9 which are enlarged views showing a
replaceable blade.
A plurality of replaceable blade joining seats 11a and
chamfered countersunk holes 11b are formed by cutting. The
replaceable blade joining seats 11a and the chamfered countersunk
holes llb formed substantially concentrically are provided for
the side surface of a disc-shape cutter body 11 perpendicular
to an axis of rotation of the cutter body 11. Note that the
replaceable blade joining seats lla and the chamfered countersunk
holes 11b are formed at the same angular intervals (note that
a necessity that the angles are the same can be eliminated) . The
chamfered countersunk hole llb is formed into a nearly circular
shape from which the outside of the outer periphery of the cutter
body 11 has been removed. The removed portion of the chamfered
countersunk hole llb is substantially 1/3 of a circle. The
diameter of the chamfered countersunk hole 11b is slightly larger
than the diameter of a replaceable blade 13 which must be joined
to the chamfered countersunk hole llb. The depth of the chamfered
countersunk hole 11b is larger than the bevel face portion of
the replaceable blade.
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The joining seat 11a formed at substantially the central
portion of the chamfered countersunk hole llb is provided for
the bottom of a rectangular countersunk hole. When the bossed
portion of the replaceable blade 13 according to first and second
embodiments to be described later.is formed into a hexagonal shape,
the foregoing rectangular countersunk hole is surrounded by the
following walls. That is, the walls include walls lld and lle
of the joining seat lla formed at substantially the same distances
from a tapped hole llg formed at substantially the central portion
(note that the distance between the walls 11d and lle of the
joining seat 11a has a tolerance which is produced when clearance
fit is performed and the distance is the same as 2 m shown in
Fig. 7 ) . The walls lld and 11e are opposite to each other at the
both side of the tapped hole llg. The walls include a wall 11c
of the joining seat lla distant from the tapped hole llg and formed
adjacent to the central portion and an outer wall 11f of the
joining seat 11a more distant from the tapped hole llg as compared
with the wall llc of the joining seat 11a.
The tapped hole 11g is formed at a position at which the
distance from the tapped hole llg and the central wall 11c of
the joining seat 11a is slightly shorter than radius r of the
polygonal cylindrical bossed portion for the replaceable blade.
Therefore, when the replaceable blade 13 has been clamped by a
countersunk head screw, the circular-arc surface of the bossed
portion of the replaceable blade is pressed against the central
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wall llc of the joining seat lla which serves as a reference
surface for joining the cutter body 11. As a result, a required
accuracy of the outer surface of the replaceable blade can be
maintained.
When the replaceable blade 13 has been clamped to the joining
seat 11a for the replaceable blade 13, a positive radial clearance
angle 8 of 0.5° to 5° (2° in this embodiment) is given to
the
cutting edge by inclining the surface of the joining seat 11a
for the replaceable blade 13 with respect to a surface which is
perpendicular to the axis of rotation of the cutter. The walls
11d and lle of the joining seat lla distant from the tapped hole
11g in the joining seat lla for the same distance and paralleling
each other and the central wall llc of the joining seat 11a more
distant from the central portion as compared with the walls 11d
and lle of the joining seat lla are finished to have-excellent
accuracy so as to serve as reference surfaces.
The depth of the joining seat 11a for each replaceable blade
and disparity of the distance between the wall 11c of the joining
seat 11a which serves as the reference surface for joining the
replaceable blade and the center of the cutter body and the
distance between the tapped hole 11g from the same exerts an
adverse influence on stabilization of the position of the outer
cutting edge line of the cutter. Therefore, machining must
carefully be performed.
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Also a case of the bossed portion of the replaceable blade
is formed into a regular octagon or quadrangle, the walls 11d
and 11e of the joining seat lla are formed to be distant from
the tapped hole for the same distance. Moreover, the wall llc
of the joining seat 11a is formed to be distant for a distance
which is slightly shorter than the foregoing distance.
A shown in Figs . 6 to 9, a replaceable blade chip 13 which
is joined to the joining seat 11a is a dish-like shape having
a diameter with which a portion of the cutting edge 13a projects
over the outer periphery of the cutter body when the replaceable
blade chip 13 has been clamped to the joining seat 11a. The cross
sectional shape of the replaceable blade chip 13 is formed into
a single side bevel circular knife. The ridge of the outer
periphery is formed into the cutting-blade line 13a. A bossed
portion 13b having an end surface 13c, which is a reference surface
which is pressed and fixed against the surface of the joining
seat 11a, is formed to project over the central portion of the
back face of the blade (the bevel surface). The bossed portion
13b has the end surface 13c which parallels a side face 13d of
the blade. The bossed portion 13b is formed into a polygonal
cylinder having an outer surface which has small circular-arc
portions.
It is preferable that the polygonal cylinder is an
even-numbered polygonal cylinder which permits easy locating
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when the position of the cutting edge is changed by rotating the
replaceable blade 13. In this embodiment, a regular hexagonal
shape is employed. When the even-numbered polygon, such as the
rectangle, hexagon or octagon, is employed, the two opposite sides
are parallel surfaces. As a result, joining to the walls 11e and
lld of the joining seat lla, which are reference surfaces, can
easily and accurately be performed. Note that the shape is not
limited to the even-numbered regular polygon. When an odd-
numbered polygon, such as a regular triangle or a regular pentagon,
is employed, the walls of the joining seat lla are made correspond
to the employed shape. The walls 11d and lle of the joining seat
lla, which are reference surfaces, can be formed into V-shapes
each having a vertex facing the central portion. A shape except
for the regular polygon may be employed from a viewpoint of
practical use.
The replaceable blade 13 has a rake side face 13d on the
side face thereof which has a central portion provided with a
joining through hole 13e countersunk-chambered at 90°. The
bossed portion 13b of the replaceable blade 13 is inserted into
the rectangular countersunk hole provided for the joining seat
11a. The hexagonal surfaces of the bossed portion are placed
along the walls llc, 11d and lle of the joining seat lla which
is a reference surface. Then, the 90°-countersunk head screw 14
is inserted into the through hole 13e of the replaceable blade
13, and then screwed in the tapped hole 11g formed in the joining
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seat lla for the replaceable blade 13, followed by tightening
the 90°-countersunk head screw 14. Since the tapped hole 11g is
formed slightly adjacent to the wall llc of the joining seat lla,
the clamping force of the 90°-countersunk head screw 14 causes
the countersunk surface to be pressed against the countersunk
surface of the through hole 13e of the replaceable blade 13 in
the axial direction of the 90°-countersunk head screw. Thus, the
fractional pressing force directed to the central portion presses
and fixes the bossed portion 13b against the wall 11c of the
joining seat lla which is the reference surface. As a result,
the replaceable blade 13 can accurately and reliably be secured
with a satisfactory accuracy of the outer surface of the
replaceable blade 13.
The length of projection of the polygonal-cylinder-shape
bossed portion 13b of the replaceable blade 13 is longer than
the depth of the joining seat 11a. Therefore, the end surface
13c of the replaceable blade 13 can reliably be seated in the
joining seat lla. The thickness of the portion of the bevel face
13f adjacent to the central portion is smaller than the depth
of the chamfered countersunk hole llb of the cutter body 11. When
the replaceable blade 13 is pressed and secured in the joining
seat 11a by the positive radial clearance angle 8 , the overall
portion of the replaceable blade 13, which does not proj ect over
the outer periphery of the cutter body 11, is embedded in the
chamfered countersunk hole llb such that proj ection from the side
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surface of the cutter body 11 toward the axis of rotation of the
cutter is prevented. Since the joining seat 11a is inclined by
2°, the portion of the replaceable blade 13 projecting over the
outer surface of the cutter body 11 proj ects over the side surface
of the cutter body 11 by a distance corresponding to the radial
clearance angle of 2°. The walls lld and 11e of the joining seat
11a, which are parallel reference surfaces of the joining seat
11a for the replaceable blade 13, serve as stoppers for preventing
rotation of the replaceable blade 13.
The squareness of the end surface 13c, which is the reference
surface for the bossed portion 13b, with respect to the 90°-
countersunk surface of the replaceable blade 13, and the
parallelism between the end surface 13c and the side face 13d
of the replaceable blade 13 are important factors. When the
position of the cutting edge is changed by rotating the
replaceable blade 13, the foregoing factors exert an influence
on the stability of the cutting edge line. It is preferable that
the replaceable blade 13 is made of a hard material for the edge
of the blade, such as cemented carbide or high-speed tool steel.
As an alternative to this, it is preferable that at least either
of the bevel face 13f or the side face 13d of the replaceable
blade 13 is coated with a chrome nitride layer made of CrN or
Cr~N or a mixture of CrN and Cr~N and having a thickness of 0.5
~.m to 6. 0 ~.un. That is, it is preferable that the replaceable blade
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13 is made of a hard material for the edge subjected to
wear-resisting surface treatment.
The replaceable blades 13 are joined to the joining seats
lla for all of replaceable blade 13 of the cutter body 11, and
then clamped with the countersunk head screws 14. Then, the
cutter is joined to the cutting machine so as to cut and align
the back pasting portion of a book which must be bound. Since
the circular replaceable blades are employed, the cutting edges
are able to cut at a small angle of inclination with respect to
the direction of the tangent of a rotational circle of the cutter.
Therefore, the wedge angle at the cutting position of the cutting
edge is considerably reduced as compared with the cross sectional
angle of the cutting edge portion of the replaceable blade 13.
As a result, a sharp cutting edge can be realized.
If the sharpness deteriorates after a large number of cutting
operations, the countersunk head screw 14 is loosen to slightly
move the replaceable blade 13 in an upward direction. Then, the
regular hexagonal cylinder of the bossed portion 13b is removed
from the hole in the joining seat. Then, the replaceable blade
13 is rotated by one pitch to expose a new cutting edge portion.
Then, the regular hexagonal cylinder is inserted into the hole
in the joining seat 11a, followed by clamping and securing the
replaceable blade 13 with the countersunk head screw 14. After
the replaceable blade 13 has been rotated six times, the
replaceable blade 13 must be again ground. Therefore, the
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replaceable blade 13 is removed. Then, a rod-shape j ig is used
which has a diameter somewhat smaller than the diameter of the
replaceable blade 13, which exhibits accurate squareness of the
surface for joining the replaceable blade 13 with respect to the
axis of rotation, which is provided with a boss arranged to be
inserted into the through hole 13e of the replaceable blade 13
and which is formed at the center thereof . The rake surface of
the side face of the replaceable blade 13 is brought into contact
with the jig, followed by screwing and securing a fixing bolt
into a central hole of the jig.
Then, the jig is rotated around the axis of rotation to
perform grinding with a flat grind stone having a grinding surface
which parallels the bevel face 13f. As a result of the foregoing
grinding operation, the cutting edge line 13a is formed on a plane
perpendicular to the central axis of the replaceable blade 13
such that the cutting edge line 13a is concentric with the central
axis of the replaceable blade 13. Since the bevel face 13f of
the replaceable blade 13 is again ground, the thickness of the
replaceable blade 13 is not substantially changed. Also change
in the thickness realized after the replaceable blade 13 has been
joined to the cutter body 11 is slight change corresponding to
the radial clearance angle 8. Therefore, substantially no fine
adjustment is required.
To realize accurate leading end of each of the replaceable
blades 13, the grinding operation must be performed such that
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the diameters of all of the replaceable blades 13 of one cutter
are the same.
Second Embodiment
A second embodiment will now be described with reference
to Figs . 10 and 11 which show a replaceable blade having a cutting
edge line formed into a polygonal shape.
A replaceable blade according to the second embodiment has
a shape of a single side bevel circular knife having a cutting
edge line formed into a polygonal shape, such as a regular
rectangle, a square pentagon, a square hexagon or a square octagon.
Figs . 10 and 11 show a replaceable blade 15 having a cutting edge
line 15b formed into the square hexagon. A pressing end surface
15a, a bossed portion 15c in the form of the hexagonal cylinder,
a 90°-countersunk hole 15c and a through hole in the countersunk
head screw are the same as the corresponding elements according
to the first embodiment.
Also the chamfered countersunk hole 11b of the cutter body
11, the walls 11c, 11d and 11e of the joining seat lla and the
replaceable blade joining seat lla are the same as those of the
replaceable blade according to thefirst embodiment. Therefore,
description of the same elements and that of the operation of
the same elements are omitted.
A re-grinding operation is performed such that a bevel face
15d is ground in such a manner that the rod-shape grinding jig
is not rotated. The amount of feeding of the grindstone is made
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to be constant to sequentially grind an indexed portions of the
swaged surface 15d for a predetermined angular degree. It is
convenient to employ a grinder having a structure with which the
axis of rotation of the j ig can be rotated and indexed. Also the
material of the blade and wear-resisting surface treatment are
the same as those according to the first embodiment.
Also the bossed portion of the replaceable blade are formed
into the square polygonal shape to correspond to the square
polygonal shape of the cutting edge line. To maintain a required
accuracy of the outer line of each of the cutting edges, it is
preferable that the bossed portion has a polygonal shape having
a small circular-arc shapes similarly to the replaceable blade
according to the first embodiment.
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