Note: Descriptions are shown in the official language in which they were submitted.
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1'1TL.E OF THE INVENTION
EI.ON(~ATED CUTTING TOOL I~OR WOOD WORKING AND APPARATUS FOR
AND METI10D OF GRINDING TIIE SAME
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an elongated cutting toot
used in wood working devices such as veneer lathes and veneer
dicers, and also to an apparatus for and a method of
grinding such an elongated cutting tool.
Description of the Related Art
An elongated cutting tool 2 conventionally used for wood
working has a s:loplng surface 'a' and a non-sloping surface
'b' as shown in Fig. 17, and a cutting edge thereof 2 has an
acute angle as 20 through 30 degrees.
Such a conventional cutting tool generally has a thin and
sharp cutting edge. ~5~hen the thin cutting edge of the
cutting tool hits against a knot or another hard portion of a
log in the cutting process, an excessive load is applied onto
the cutting edge. 'The cutting edge is thereby pressed back
outwardly to separate from the log and then inwardly onto the
log surface as a counteraction. The sharper cutting edge
causes greater vibration of the cutt:in g edge due to the
press-back and press-on cycle. Such vibration results in t:hc
uneven thickness of a veneer cut from the log and undesirably
damages the cutting edge hit against a knot, a resin pocket,
or another hard portion of the log.
'fhe applicant of the present invention has proposed an
improved method of superfinishing a cutting edge, wherein t;he
cut:t:ing edge of an elongated cutting tool is finished to have
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a curved surface by multiple-taper grinding as disclosed in
.1APANESE PATENT LAYING-OPEN GAZETTE No. 63-9f3163. 'this
method attains a thicker cutting edge with sufficient cutting
quality.
The elongated cutting tool having a cutting edge
superfinished according to the above method has greater angle
and thickness than the conventional cutting tool to give
longer service life. Improvement in the angle and thickness
of the cutting edge is, however, not sufficient, which st..ill
causes unstable cutting or vibration of the cutting edge
against the cut surface of the log.
In order to prevent vibration of the sharp cutting edge, a
tip of a non-sloping surface of the cutting tool is ground
off by a certain angle. Although this grinding procedure
reduces the vibration of the cutting edge to some extent, the
ground tip of the non-sloping surface slides <zgainst a rear
side of a veneer currently cut from the log to damage or even
crack the rear side of the veneer.
SLJMMARY OI~ THE INVENTION
One object of the invention is to provide a novel cutting
tool used in wood working, which has a sufficiently t;hic~k
cutting edge allowing stable cutting of a veneer from a Log.
Another object of the invention is to provide an apparatus
for and a method of grinding a cutting edge to have a
favorable shape and ti relatively large angle.
The above and other related object-s are realized by an
elongated cutting tool used in wood working, wherein a
cutting edge thereof has an arc-shaped first surface and an
arc-shaped second surface finished by multiple-taper grinding
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from a tip port;ion to a base portion of the respective
surfaces.
An apparatus for grinding such a cutting tool includes a
table which an elongated cutting tool ext:ending along a
longitudinal axis of the table is mounted on, a fixing
element for pressing the cutting tool upright against an
upright plate, and a carriage which is reciprocatingly
movable along tlse longitudinal. axis of the table. 1'he
carriage is provided with a pair of grinding wheels which are
respectively movable into and out of endwise grinding contact;
with an upper surface and a lower surface of the cutting edge
of the uprighC cutting tool at desirable angles. The
apparatus further includes a control mechanism for
controlling a moving distance and an inclined angle of each
grinding wheel according to a preset number of grinding steps
and a predetermined grinding depth and a predet:ermin ed
grinding angle at each grinding step for each surface of the
cui:ting edge .
The invention also provides a method of multiple-taper
grinding a first surface and a second surface of a cutting
edge of such an elongated cuttirug tool with a pair of
grinding wheels mounted on a carriage movable along a
longitudinal axis of a table onto which the cutting tool
extending along t:he l.ongi tudinal axis thereof is fixed
up right. The first surface and the second surface of the
cutting edge are multiple-taper ground accorci.i.nl,~ t.o desirable
grinding angles and grinding depths set by a control circuit
to have an arc shape, respectively.
The elongated cutting tool of the invention has a first:
surface and a second surface, which are multiple-taper ground
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from a tip to a base thereof to have an arc shape,
respectively. 'this gives a sufficient thickness to t;he
cutting edge. 'fh a apparatus of the invention allows
relatively easy multiple-taper grinding with a control
mechanism for contro7l.ing a moving distance and an inclined
angle of each grinding wheel according to a preset number of
grinding steps and a predetermined grinding depth and a
predetermined grinding angle at each grinding step for each
surface of the cutting edge.
These and other objects, features, aspects, and advantages
of the present; invention will become more apparent from the
following detailed description of the preferred embodiment
with the accompanying drawings.
IIRlEF DhSCRIfTlON OF TIfE DRAWINGS
Fig. 1 is a front view illustrating a general structure of
a grinding apparatus for grinding an elongated cutting tool.
aS a preferred embodiment according to the invention;
fig. 2 is a plan view showing the grinding apparatus of
F.i g. 7 ;
Fig. 3 is a side view illustrating part of the grinding
apparatus of I~ i g. 1 ;
Fig. 4 is a rear view showing part of the grinding
apparatus of Fig. 1;
Fig. 5 is a partly broken plan view showing a primary part
of the grinding apparatus of F.ig. 2;
Fig. 6 is an enlarged side view showing the primary part
of Fig. 5;
Fig. 7 is an enlarged front view showing the primary part:
of Fig. 5;
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Fig. 8 is an enlarged side view illtrat:rating a primary
part of a braking mechanism;
Fig. 9 is <i partly omitted front, view showing the braking
mechanism of Fig. 8;
Fig. 10 is a block diagram showing arr autornat:ic cont:rol
system with a counter;
Fig. 11 is a block diagram showing a manual control system
with a counter;
Fig. 12 is a block diagram showing an automatic control
system based on a preset amount;
Fig. 13 is a block diagram showing a manual control system
based on a preset amount;
Fig. 14 is a block diagram showing an automatic control
system based on an image signal;
Fig. 1.5 is a block diagram showing a manual control system
based on an image signal;
Fig. 76 is a schematic view showing a cutting edge of an
elongated cutting tool ground according to the method of the
invention; and
Fig. 17 is a schematic view showing a cutting edge of an
elongated cutting tool ground according to a conventional
method.
DESCRIPTION OF 'fIIE PREFERRED EMBODIMENT
An apparatus for grinding an elongated cutting tool
embodying the invention is first, described in detail based on
t;he drawi ngs .
Fig. 1 is a front view showing a general structure of a
grinding apparatus of an embodiment; Fig. 2 is a plan view of
the grinding apparatus; and Fig. 3 and Fig. 4 are a side view
and a rear view showing part of the grinding apparatus,
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rCSpeCt:1 VCly.
As clearly seen ir-r fig. 3, in the grinding apparatus of
the embodiment, an elongated cutting tool 2 to be ground is
held on a table 3 to extend along a longitudinal axis of the
table 3 and is pressed upright against an upright plat:e 1 by
a plurality of fixing elements 4.
Tyre table 3 has a lengt:h equal to or greater t:han the 1 ength
of the cutting tool 2.
An inverse U-shaped carriage 6 with rollers 5 on the four
corners thereof' is mounted on the table 3 and is provided
with a driving mechanism 7. The driving mechanism 7 for
moving the carriage 6 includes a prime mover 8 mounted on the
upper portion of the carriage 6, a belt 11 running between a
pulley 9 of the prime mover 8 and another pulley 10 supported
on one end of a rotary shaft to be disposed below the pulley
9, a chain pulley 12 attached on the other end of the rotary
shaft to be connected t:o the pulley 10, and a chain 13
supported in tension on both .Longitudinal ends of the table 3
by means of a spring (not. shown) to engage with the chain
pulley 12. 'The driving mechanism 7 makes the carriage 6
movable along the longitudinal axis of the table 3.
A pair of support chain pulleys 14 mounted on both sides
of and adjacent to the chain pulley 12 as shown in Pig. 4 are
engaged with the chain 13 to prevent excessive vibration of
the chain pulley 12.
'rhe carriage 6 is provided with a pair of brackets 15,15
projecting downward from a top el.ernent of the carriage 6 and
disposed in parallel across the longitudinal axis of t:he
table 3. A pair of base plates 16 and 17 facing t:o each
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of:her across the longitudinal axis of the table 3 are
pivotably supported on between the pair of brackets 1;i,75 <rs
clearly seen in L~'igs. 2 and 3. A first face of the base
plate 16 is opposed to a sloping surface ' a' of t:he cutt:i ng
tool 2 uprightly supported to extend over the longitudinal
axis of the table 3 whereas a second face of floe base plate
17 is opposed to a non-sloping surface ' b' of the cut.ti rrg
tool 2. Here the second face is opposite to tire first face
across the longitudinal. axis of the t:able 3. Angle set.t:ing
units or angle adjustors 18,78 for varying t:he inclined
angles of the base plates 16 and 17 are further mounted on
the base plates 16 and 17, respectively.
A typical mechanism of the angle adjustors 18,18 attached
to the base plates 16 and 17 is described briefly. A pinion
gear 21 activated via a chain 20 by a prime mover 19 mount:ed
on the carriage 6 engages with a fan-shaped rack gear 22
attached t:o one end of the base plate 16, so that. the base
plate 16 disposed on the side of the sloping surface 'a' of
the cutting tool 2 is pivotably moved around the joint with
the bracket l:i. The base plate 17 disposed on the side of
the non-sloping surface 'b' of the cutting tool 2 is
connected to another prune mover 23 mounted on the carriage 6
via a chain 24 suspended on a gear of the prime mover 23.
1'he pinion gear 21 and the prime mover 23 are respect.ivcly
provided on a shaft; thereof with rotational angle detection
units or rotational angle detectors 25,2 each including an
encoder and a linear transformer for detecting the inclined
angles of the base plates 16 and 17 inclined corresponding to
the pivotal movement thereof. Each base plate 76 or 17 is
further provided with a prime rnover 26 as typically shown in
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Fig. 5. A belt 31. runs between a pulley 27 of the prime
mover 2Ei and another pulley 30 slidable with respect to a
drive shaft 29 supported by means of a first bearing 28.
Substantially U-shaped guide plates 32,32 are further
mounted on the base plates 16 and 17, respectively. A pair
of sliding guides 3:3,33 including linear-ways are mounted on
ttte diverged elements of each U-shaped guide plate 32 as
clearly seen in Figs. 5, Ei, and 7. Although Figs. 5, Ei, and
7 only show the elements on the base plate 16, there is a
similar structure on the base plate 17. A tubular sliding
body 34 with the drive shaft 29 securely fitted therein is
movably supported on the pair of sliding guides 33,33 by
means of a pressing member 35.
The pressing member 35 includes a transport unit 40 and a
sliding unit 44 as shown in Fig. 6. The transport unit 40
includes a second bearing 37 disposed above the first bearing
28, a rack member 36 fitted in the second bearing 37, and a
bracket 39 attached t.o the end of t=he rack member 36. The
rack member 36 of the transport unit 40 is movable towards
t:he cutting edge of the cutting tool 2 by means of a motor
38. In the sliding unit 44, a fluid cylinder 41 is attac:hect
to the upper end of the bracket 39, and a piston rod 42 of
the fluid cylinder 41 is connected to a control plate 43
disposed above the sliding body 34.
A pair of grin ding wheels 45,45 for grinding the sloping
surface 'a' and the non-sloping surface 'b' of the cutting
tool 2 are attached to the ends of the drive shafts 29
disposed on the base plates 16 and 17, respect=ively. A
grinding depth of each grinding wheel 45 is sei= corresponding
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to a feeding amount of t:he transport unit 40. A grinding
depth controller 46 for adjusting the grinding depth is
activated by the motor 38 for driving the rack member 36 and
stopped when i t i s c;onfi rmed by a proxi mi ty swi t.c;h ( not:
shown) that an indication of a dial indicator (not shown)
reaches a preset amount 47 (see Figs. 12 and 13). The preset
amount 47 represents a maximum forward movement of the
grinding wheel 45, that is, a maximum grinding depth. 41'hcn
the grinding depth reaches the preset amount: 47 at each
grinding step, grinding operation is immediately stopped.
This prevents an uneven surface of the cutting tool 2 from
being excessively ground by the grinding wheel. 45 along the
longitudinal axis of the cutting tool 2.
A rail member 48 is disposed above the base plate 16 or 17
parallel. to a sliding direction of the drive shaft 29 as
clearly shown in Fig. 7. A slide member 49 such as a roller
or a linear v~ay is attached onto the rail 48, and a balancer
50 is suspended from the rail 48 via the slide member 49.
'fhe sliding unit 44 and t;he balancer 50 are connected to each
other by a link 52 with a fulcrum on one end of a link
support 57 projected from the transport unit 40 towards the
grinding wheel 45. The weight of the balancer 50 is
determined according to the length of the link 52 from the
fulcrum of the link support 51.
In the transport unit: 40 on the base plate 16 or 17
sliding.ly movable relative to t;he cut;ti.ng tool 2 and the
sliding unit 44 supporting the grinding wheel 45 for grinding
the cutting tool 2, the grinding depth is adjusted by m<~ki.ng
use of fluid pressure applied from the fluid cylinder 41 and
the piston rod 42 connected thereto. Alternatively, a spring
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m<iy be used for the same purpose.
Ln the embodiment, the grinding depth controller 46 is
activated by the motor 38 for driving the rack member 36 and
stopped when it is confirmed by a proximity switch (not
shown) that an indication of a dial indicator (not shown)
reaches the preset amount 47. An enc:ocier or a :Linear
transformer may be used in place of the dial indicator.
A pair of detectors 53 (see Fig. 4), each including a
limit switch, a photo-electric tube, and a proximity swit:c:h,
are attached to both ends of the base plates 16 and 1.7. A
cooling water groove 54 (see Fig. 3) spans the whole moving
distance of the grinding wheel 45 between the table 3 and the
upright plate 1.
The sliding unit 44 is further provided with a brukin g
mechanism 55 as shown in Digs. 8 and 9. The braking
mechanism 55 includes a piston rod 5f> for pressing one of the
sliding guides 33 disposed on both sides of the sliding body
34, and a cylinder 57 for actuating the piston rod 56 by
making use of fluid pressure.
Although the fluid pressure cylinder i.s applied to the
braking mechanism ~5 in this embodiment, any other mechanism
may be employed alternatively, for example, actuating a screw
by a servo motor, or locking by means of a plunger
corresponding to OTC and OFF of an electromagnet.. The number
of the braking mechanism is also not limited.
Figs. 10 through 15 are block diagrams showing typical
examples of multiple-taper grin ding the cutting edge of the
cutting tool 2 from the tip portion to the base portion
thereof to have an arc-shaped sloping surface 'a' and an
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arc-shaped non-sloping surface 'b'.
Figs. 10, 12, and 14 show automatic control systems
wherein grinding data including numbers of grinding steps and
grinding depths and grinding angles corresponding to the
respective grinding steps are previously stored in a pair of
arithmetic units 60,60, one for the sloping surface 'a' and
t;he other for t:he non-sloping surface 'b' of the cutting
edge. A desirable grinding pattern is then selected out of
the grinding data. On the other hand, Figs. 11, 73, and 15
show manual control systems wherein a number of grinding
steps and grinding angles and grinding depths at the
respective grinding steps are input into a memory unit 61
prior to every grinding operation.
Grinding depths at each grinding angle are detected with
one of the following three mechanisms.
in a first mechanism shown in Figs. 10 and 11, the
grinding depth is detected by the detector 53 as a number of
reciprocating movement; of the grinding wheel 45. 'the number
of the reciprocating movement is then compared with a preset
count in a counter 63.
I.n a second mechanism shown in Figs. 12 and ~3, a preset
amount 47 in each dial indicator is determined by considering
abrasion of the grinding wheel 4;i. An indication of the dial
indicator detected as a grinding depth is then compared with
the preset amount 47 by a proximity switch or a like element.
In a thi rd mechanism shown i n Fi gs . 14 arnd 15 , a process
of grinding the cutting tool 2 is observed with a video
camera 65. An image signal 66 from the video camera 65 is
then compared wi t:h a predetermined grinding margin 64 of the
cutting tool 2. In this mechanism, the driving mec;h anism 7
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includes a t;ime-measuring clement (not shown) such as a tuner
for expressing a movin6r distance of the carriage 6 as a
function of the time or a measuring element 62 (see I~'ig. 4)
for detecting a moving distance and a position of the
carriage 6.
In the above three mechanisms, after a grinding angle of
the grinding wheel 4;i set by the angle ad,justor 18 is
detected by tine rotational angle detector 25, the driving
mechanism 7 actuates the grinding wheel 45 to reciprocate
along the longitudinal axis of the cut;t:ing tool 2. N'hen t;he
number of reciprocating movement reaches t:he preset count in
the counter 63, when the indication in t;he dial indicator
reaches the preset amount 47, or when the image signal ff
from the video camera 65 reaches the grinding margin 64, the
arithmetic unit 60 stops the driving mechanism 7 and thereby
the grin ding wheel 45 and actuates the angle adjustor 18 to
prepare for grinding at a next step.
'The apparatus for grinding the cutting edge thus
constructed is operated in the following manner.
'The cutting tool 2 which has roughly been ground with a
knife grinder is vertically laid on the table 3 and pressed
by the fixing elements 4 to face the cutting edge thereof
upward. An automatic or manual control system is then
select;eci. When data for- a certain wood material has
empirically been obtained, t:he manual control cyst:em is
applied to select a desirable grinding pattern out of the
stored data including grinding angles and grinding depths at
each step of multiple-taper grinding. On the contrary, when
there is no data obtained for a wood material, the manual
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control system is applied to find the desirable grinding
angle: and grinding depth by trial and error.
A number of grinding steps and grinding angles and
grinding depths at the respective grinding steps are
determined for the sloping surface 'a' and the non-sloping
surface 'b' of the cutting edge.
In one example shown in Fig. 16, both the sloping surface
'a' and the non-sloping surface 'b' are finished by triple-
taper grinding. The grinding angle and the grinding depth
for the sloping surface 'a' are set equal to 30 degrees and
5/100 through 8/100 nun (corresponding to the count 14 in the
count:cr 63) at a first grinding step, 26 degrees and 10/1.00
through 15/100 mm (corresponding to the count 2 in the
counter 63) at a second grinding step, and 23.30 degrees and
20/100 through 30/100 mm (corresponding to the count 2 in the
counter 63) at a third grinding step.
'fhe grinding angle and the grinding depth for the non-
sloping surface 'b' are set equal to 10 degrees and 10/100 mm
(corresponding to the count. 12 in the counter 63) at a -first
grinding step, ~ degrees <ind 20/100 mm (corresponding to t;he
count 2 in the counter 63) at a second grinding step, and
0.10 degrees and 20/700 mm (corresponding to the count 2 in
the counter 63) at a third grinding step.
In t;he above example, the count at the second or third
grinding step is significantly smaller than the same at tlrc
first grinding step. This is attributable t.o a greater
grinding depth at the first grinding step as clearly sc;en in
Fig. 16.
After the suitable control system is selected, the
grinding angles of the pair of grinding wheels 45,45 for
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grinding the sloping surface 'a' <ind the non-sloping surface
'b' of the cutting edge of t:he cutting tool 2 are set by
actuating the prime movers 19 and 2:3 based on signals sent
from the angle acljustors 18,18 and then checked by the
rotational. angle detectors 25,25.
An initial grinding depth for the cutting edge is
determined by the grinding depth controller 46. The prime
mover 8 is driven to activate the carriage 6 t.o move the pair
of grinding wheels 45,45 to the sloping surface 'a' and the
non-sloping surface 'b' of the cutting edge of the cutting
tool '?. When the carriage 6 reaches t;he cutting tool 2, the
fluid cylinder 41 is actuated to supply fluid from each port
thereof to make the pressure in a rear cylinder chamber of
the cylinder 41 higher than t:hat of a front cylinder chamber
thereof and stretch the piston rod 42. Accordingly, the rack
member 36 is moved towards t:he cutting edge by the motor 38
while t:he control plate 43 is pressed forward.
When the rack member 36 is rnoved i'orward along the bearing
37, the piston rod 42 of the fluid cylinder 47 attached to
the bracket 39 slides the sliding body 34 with the drive
shaft 29 fitted therein in the axial direction via the
control plate 43 to bring each grinding wheel 45 in contact
with each surface of the cutting edge of the cutting tool 2.
Al though a backward moment i s app lied to the ciri ve shaf t: 29 ,
each grinding wheel 45 remains in contact with the cutting
edge because of a forward pressure of the piston rod 42 of
the fluid cylinder 41 against the drive shaft 29. The
magnitude of the fluid pressure applied to the drive shaft 29
is determined by adding an expected degree of unevenness in
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rough grind to the grinding depth for a ricasso or a base
p ort:ion of the cutting t;ool 2 with respect to the cutting
edge. 'fhe amount of the backward movement of the drive shaft
29 against the fluid pressure t:hereby represents a maximum
grinding depth required for the ricasso or the base portion
of the cutting tool 2.
'fhe base plate lf> or 17 is inclined by a predetermined
angle set by the angle adjust:or 18, and the dead weights of
each grinding wheel 45 and the sliding unit 44 are about to
move the slicing unit 44. The balancer 50 on the rail member
48 projected from the base plate 16 or 17 moves along the
rail member 48 in a direction to balance t:he dead weights
thereof with the fulcrum on the link sup port 51, thus
allowing stable and consi;ant grind.
The fluid is released from the rear cylinder chamber of
the fluid cylinder 41 so as to contract; the piston rod 42 and
actuate the driving mechanism 7 to move the carriage 6 back
to its original waiting position. The prime mover 26 is then
actuated to apply a rotat:ional force to each grinding wheel
45.
The chain pulley 12 starts rotation wit:h actuation of t:he
driving mechanism 7. Since the chain pulley 12 is supported
by the support chain pulleys 14 mount:ed on both sides of the
chain pulley 12 to increase a running force applied onto the
chain 13, the carriage 6 smoothly moves and each grinding
wheel 45 favorably starts grind of t:he cutting tool 2. The
pair of detectors 53,53 disposed on either side of the
carriage Ei detect the position of the carriage 6 with respect
to the cutting tool 2.
lVhen the carriage f> is activated t:o move from a first end
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i n a fi rst; d i rect.ion along the 1. ont,~i tuci.i nal <rx i s ol' t:he
cutting tool 2, fluid is supplied into the rear cylinder
chamber of the fluid cylinder 41 to st:retch the piston rod
42. Each grinding wheel. 45 is accordingly pressed against
the cutting edge of the cutting tool 2 to start grinding.
When the detector 5:3 detects that t:he carriage G reaches a
second end of the cutting tool 2, the cylinder 57 of the
braking mechanism 55 is synchronously ac:t.ivat.ed to press the
piston rod 56 against the sliding guides 33 and :loc:k the
sliding movement of the sliding body 34.
After the carriage 6 continues moving in the first
direction to pass by the second end of the cutting tool 2
under the above locking condition, the prime mover 8 is
inversely driven to return the carriage 6 to Lh a second end
of the cutting tool 2. When the measuring element 6z det;ec:ts
the return of the carriage 6, the lock of the braking
mechanism 55 is roleased to move the carri~ige 6 .in a second
direction, that is, from the second end to the first end.
The above reciprocating movement in the first direction and
the sec:onci direction is repeated by a predetermined number of
times.
In a modified system wit;bout the braking mechanism 55, the
grinding wheel 45 is separated from the cutting edge of the
cut: t;ing tool 2 by stopping fluid supply .into the rear chamber
of the fluid cylinder 41 or driving the motor 38 t,o inversely
move the rack member 36 and is brought into contact with the
cutting edge by re-starting fluid supply or moving the rack
member 36 in the normal direction.
lYhen grinding at the initial grinding angle is completed,
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t:he driving mechanism 7 is stopped and the braking mechanism
55 is released. Implementation of the first grinding step is
dot:errnined based on the count in the count:er 63, the preset
amount 47, or the image signal E>6 from the video camera 65 as
described above. The angle ad,justors 1_8 are then activated
to set second grinding angles at a second grinding step for
the sloping surface 'a' and the non-sloping surface 'b' of
the cutting edge. Each angle ad,justor 18 is driven directly
in the automatic control system or via the memory unit E>1 in
the manual control system. After the second grinding angle
is set by actuating the prime mover 19 or 23 and c:hocked by
the rotational angle detector 25, the driving mechanism 7 is
driven again to start grinding at the second grinding angle.
Each time when the grinding angle is changed, the balancer 50
slides on t:he rail member 48 via the slide member 49 to
balance the dead weights of t:he grinding wheel 45 and the
sliding unit 44, thus preventing an excessive weight from
being applied onto the cutting edge of the cutting tool 2.
The above procedure is repeated for a predetermined number
of grinding steps to complete multiple-taper grinding of tire
cutting edge from a tip portion to a base portion thereof' to
give a first arc-like shape to the sloping surface 'a' and a
second arc-like shape to the non-sloping surface 'b' as shown
in Fig. 16. Although the grinding depth decreases from the
tip portion to the base portion of the cutting edge in the
embodiment, it may alternatively increase from the base
portion to the tip portion.
As described above, the cutting ccige of t;he e-longated
cutting tool of the embodiment has a first surface and a
second surface, which are multiple-l.aper ground from a t.ip
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portion to a base portion thereof to have an arc shape,
respectively. This gives a sufficient thickness i.o t:he
cutting edge of the cutting tool, which preveni.s excessive
vibration of the cutting edge and reduces damage or crock of
a rear face of a veneer cut from a log, thereby allowing
stable and constant cutting of veneers from a log.
'fhe apparatus of the embodiment allows relatW ely easy
multiple-taper grinding with a control mechanism for
controlling a moving distance and an inclined angle of each
grinding wheel. according to a preset number of grinding steps
and a predetermined grinding depth and a predetermined
grinding angle at each grinding step for each surface of the
cutting edge.
Since there may be many other modifications, alternations,
and changes wit:bout departing from the scope of the
invention, it is clearly understood that the above
embodiments are only illustrative and not restrictive in any
sense.
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