Note: Descriptions are shown in the official language in which they were submitted.
8 ~
The present invention relates to an ~n~ul ~r cutter
c~nnecting a~a~atus for cQn~cting an ~nm~-~r uu~e
to a dr~ n~ m~ch~ne used-for dr~ relatiYely deep
holes in a workpiece made of a.hard material, and an
s ~nnlll ~r uuL~e~ connected.by such a connecting apparatus
to the ~r~ n~ mach~ne~ and more part~cul ~rly to an
annular ~Ler ~o~ cting apparatus for csnne-cting an
~nnl~lAr-cutter to a dr~ ng ma~h~ne with ease,
receiving only an annular cutter suited for the
0 dr~ll1n~ mar,h~n~ and ~ev~ing any ~n~ r ~u~e~ not
suited ~l-e~e~or from being connected to the dr~ ng
m~ch~ne, and such an ~nn~ r ~u~e
The ~onv~ll~on~l dr~ n~ r2-h~ or dr~ n~ a
workpiece made of a hard material generally forms holes
by driving an annular cutter having downward directed
blade edges at a constant-Lo~a~on~l speed and feed.
Upon dr~ ng a workpiece made of a hard material on
this dr~ ng r~Chi ne, it is necessary to change the
annular cutter which is now used when it is not suited
for the workpiece to be drilled.
There have been developed various annular cutter
connecting apparatuses which facilitate replacement of
annular cutters, and annular cutters which can be
replaced easily. There are variety of annular cutter
connecting apparatuses, the simplest type of which
connects an annular cutter to an arbor by means of a
bolt, and a relative complicated type of which uses
2138581
locking members such as balls for holding the arbor.
The present invention will be described by way of
embodiments with reference to the accompanying drawings
in which:
S Fig. 1 is a longitudinal cross-sectional view of a
conventional annular cutter connecting apparatus;
Fig. 2 is a side view of the main part of the
annular cutter connecting apparatus of Fig. l;
Fig. 3 is a transversal cross-sectional view of
the fixing portion of another conventional annular
connecting apparatus using a fixing bolt with an
annular cutter fixed thereto;
Fig. 4 is a longitudinal cross-sectional view of
the main part of an annular cutter connecting apparatus
according to one embodiment of the present invention in
which an annular cutter to be connected the arbor of
the apparatus is separated from the apparatus;
Fig. 5 is a longitudinal cross-sectional view of
the main part of the annular cutter connecting
apparatus of Fig. 4 with the annular cutter connected
to the arbor;
Fig. 6 is a longitudinal cross-sectional view of
the pushing sleeve of the annular cutter connecting
apparatus of Fig. 4;
Fig. 7 is a cross-sectional view along line 7-7 in
Fig. 6;
Fig. 8 is a cross-sectional view along line 8-8 in
5 8 1
_ -3-
Fig. 4;
Fig. 9 is a cross-sectional view along line 9-9 in
Fig. 4;
Fig. 10 is a cross-sectional view along line 10-10
in Fig. 5;
Fig. 11 is a front view of a first embodiment of an
annular cutter according to the present invention;
Fig. 12 is a side view of the annular cutter of
Fig. 11;
Fig. 13, which appears on page 5 of the drawings, is
a transversal cross-sectional view of second and third
embodiments of annular cutters according to the present
receiving portions;
Fig. 14 is a front view of the third embodiment of
the annular cutter according to the present invention;
Fig. 15 is a side view of the third embodiment of
the annular cutter;
Fig. 16 is a front view of a fourth embodiment of an
annular cutter according to the present invention; and
Fig. 17 is a side view of the annular cutter of
Fig. 16.
A conventional annular cutter connecting apparatus
which has a relative complicated structure as disclosed
in Japanese Laid-open Patent Application 62-74515 will be
described with reference to Figs. 1 and 2.
The conventional annular cutter 1 connected to an
arbor 2 of a drilling machine (not shown) and transmits
the rotation and the feed required for drilling
~r~
2138581
_
operation from the drilling machine to an annular
cutter 8. A cylindrical rotation transmitting member 3
is irrotationally connected to the arbor 2 by means of
a key 4. A plurality of holding holes 6 for holding
fixing balls 5 are formed in the lateral wall of the
lower portion of the rotation transmitting member 3 so
as to be directed toward the axis of the rotation
transmitting member 3.
On an intermediate portion of the inner peripheral
surface of the rotation transmitting member 3 are
formed a plurality of engaging portions 7 (Fig. 2)
which extend toward the central axis of the member 3
and transmit rotation from the rotation transmitting
member 3 to the annular cutter 8. A pushing sleeve 9
for pushing the fixing balls 5 toward the central axis
of the rotation transmitting member 3 surrounds the
rotation transmitting member 3 so as to be slidable
axially thereof. Between the pushing sleeve 9 and the
rotation transmitting member 3 is provided a
compression coil spring 10 for urging the pushing
sleeve 9 downward. The pushing sleeve 9 is held by a
holding ring 11 fixed to the outer peripheral surface
of the rotation transmitting member 3 so that the
pushing sleeve 9 is prevented from slipping off the
rotation transmitting member 3.
The annular cutter 8 has a downwardly open
cylindrical body having a plurality of blades (not
2138~81
5-
shown) formed on the lower end thereof. On the upper
end of the cylindrical body is formed a cylindrical
shank portion 12 inserted in the lower portion of a
cylindrical central hole (hereinafter referred to as
the "fixing hole") formed by the inner peripheral
surface of the rotation transmitting member 3. Axially
projecting portions 13 engageable with the engaging
portions 7 are formed on the upper end of the shank
portion 12. An annular groove 14 for receiving the
fixing balls 5 is formed in an intermediate portion of
the outer peripheral wall of the shank portion 12.
A center pin 15 for determining the drilled
position axially slidably passes through the central
hole of the annular cutter 8. An annular engaging
groove 16 for receiving engaging balls 17 is formed in
the upper end portion of the center pin 15. The
annular cutter 8 is connected to the arbor 2 in the
fixing hole by pushing the engaging balls 17 into the
engaging groove 16. The center pin 15 is urged
downward by a compression coil spring 18 through the
balls 17, and a sealing member l9 is abutted against
the upper shoulder of another annular groove 20 so as
to prevent cutting oil from flowing downward from the
cylindrical central hole in the arbor 2, when the
center pin 15 is not in use. During the drilling
operation, however, the lower end tip of the center pin
15 is pressed against a to-be-drilled workpiece (not
2138581
-6-
shown) made of a hard material, and the center pin 15
is pushed in the fixing in the rotation transmitting
member 3 against the urging force of the compression
coil spring 18. Accordingly, the sealing member 19 is
released from the shoulder of the annular groove 20 of
the annular cutter 8, and the cutting oil is supplied
from the cylindrical hole of the arbor 2 to the blade
edges of the annular cutter 8, whereby the drilling
operation is performed smoothly.
The annular cutter 8 is fixed to the rotation
transmitting member 3 in the following way. First, the
pllsh~ng sleeve 9 is moved upward against the urging
force of the compression coil spring 10. Next, the
shank portion 12 of the annular cutter 8 is inserted
into the fixing hole of the rotation transmitting
member 3 until the projecting portions 13 engage the
engaging portions 7. In this state, the pushing
portion 21 of the pushing sleeve 9 is displaced from
the fixing balls 5, and the fixing balls 5 face the
cylindrical ball-escaping hole 22 of the sleeve 9 so
that the balls 5 are movable radially outward. Thus,
the shank portion 12 of the annular cutter 8 is
inserted freely in the cylindrical hole of the rotation
transmitting member 3.
When the annular cutter 8 is fully inserted in the
rotation transmitting member 3, the pushing sleeve 9 is
released. Then, the pushing sleeve 9 is moved downward
2138581
by the urging force of the compression coil spring 10
and pushes the fixing balls 5 into the annular groove
14 of the shank portion 12. In this way, the annular
cutter 8 is fixed to the rotation transmitting member
3.
Upon drilling a workpiece made of a hard material,
the annular cutter now on the drilling machine must be
replaced by an annular cutter having a diameter suited
for holes to be formed, if the annular cutter now on
the drilling machine does not have such a suitable
diameter.
However, the conventional annular cutter
co~necting apparatus can connect any annular cutter to
the arbor so long as the inner diameter of fixing hole
of the rotation transmitting member corresponds to the
outer diameter of the shank portion of the annular
cutter and the annular groove coincides with fixing
balls. Thus, an annular cutter not suited for the
driving capability of a drilling machine and for the
material of a workpiece is sometimes connected to the
arbor 2 mistakenly. If the drilling operation
continues without noticing this mistake, unexpected
high cutting resistance is produced during the drilling
operation. As a result, the driving mechanism of the
drilling m~chine tends to be damaged and/or the blade
edges of the annular cutter 8 are apt to be broken.
In case wheFe only blade edges are broken, this
2138581
problem can be solved by replacing the annular cutter 8
with a suitable one. When, however, the driving
mech~n~sm of thé drilling machine is broken, the
drilling operation must be interrupted for a long time
in order to repair the driving ~ech~n1sm~ deranging the
production plan. When the annular cutter 8 is not
suited for the material of a workpiece, burrs tend to
be produced to lower the dimensional accuracy of the
formed holes, even if the holes can be formed. As cut
chips are wound around the annular cutter 8, the
pushing sleeve 9 is sometimes pushed up against the
urging force of the compression coil spring lO, and the
annular cutter 8 is apt to be adversely loosened or
removed from the arbor 2.
When the annular cutter 8 is fixed to the arbor 2
as shown in Fig. 2, the pushing sleeve 9 is lowered so
that the annular cutter fixing balls 5 coincide with
the escaping hole 22 formed in the lower end portion of
the pushing sleeve 9 and are set in a waiting state in
the escaping hole 22. In the conventional annular
cutter connecting apparatus 1 of a general type, part
of each ball 5 projects from the inner peripheral
surface of the rotation transmitting member 3 into a
central bore defined by the inner peripheral surface of
the rotation transmitting member 3 (Fig. 1). Flat
faces 23 each having a depth corresponding to the
extended amount of each ball 5 into the central bore
2138581
g
are formed on the parts of the outer peripheral surface
of the shank portion 12 of the annular cutter 8, which
parts extend from the annular groove 14 to the upper
end of the shank portion 12. When the shank portion 12
is fixed to the arbor 2, the flat faces 23 align with
the corresponding balls 5, and then the shank portion
is pushed into the central bore.
Any annular cutter can be connected to the arbor 2
so long as the annular cutter is provided with a shank
portion 12 having an outer diameter corresponding to
the inner diameter of central hole of the arbor 2 and
flat faces 23 for receiving the balls 5 extending from
the holding holes 6 into the central hole. Thus, the
subject matter in that only a suitable annular cutter
can be fixed to a specific arbor cannot be achieved by
the conventional annular cutter 1.
Japanese ~x~ml ned Utility Model Application No.
64-3603 discloses one of the conventional annular
cutter connecting apparatus which uses a bolt by which
an annular cutter is connected to an arbor. This
conventional apparatus will be described with reference
to Fig. 3. The shank portion 24 of an annular cutter
is inserted in the central bore 26 of an arbor 25.
Then, a fixing bolt 27 provided in the arbor 25 is
turned to engage a flat face 28 formed on the lateral
wall of the shank portion 24, and the annular cutter is
connected to the arbor 25. The center ~l of the shank
~ ~ 3 ~ ~ 8 1
--10--
port~on 28 should coincide with the center ~2 of the
receiving hole 26 of the arbor 25. Actually, however,
slight manufacturing errors of the shank portion 24 and
the receiving hole 26 and/or fitting tolerances between
them produce a center displacement ~ ranging from
1/100 to 1/50mm. This displacement provides
eccentricity of the annul ar cutter, giving an adverse
effect to the ~nnlllAr cutter.
The first ob~ect of the present invention is to
provide an annular cutter ~o~ner-ting apparatus which
connects to a dr~ ng m~ch~ne only an ~nn~ r cutter
suited for the dr~ ng mach~e and ~ev~llts a p~ h;n~
sleeve of the apparatus from being loosened or removed
even when cut chips are wound around the pl~sh1ng sleeve
during the drilling operation.
The second object of the present invention is to
provide an annular cutter to be connected to a drilling
machine by means of such an annul ar cutter co~ecting
apparatus.
In order to achieve the first object of the present
invention, an annular cutter connecting apparatus comprises
an arbor including cylindrical one end portion having an
outer diameter, a central bore and a plurality of holding
holes arranged circumferentially in the end portion and
communicating with said central bore, locking members for
connecting an annular cutter to the arbor received in the
receiving holes, a sleeve rotatably surrounding
A
the end portion of the arbor. The sleeve is provided
with a first control face having an inner diameter
slidable over the outer diameter of the end portion of
the arbor, for causing the locking members to project
from the holding holes by a predetermined amount into
the central bore when the first control face engages the
locking members. The sleeve is further provided with
second control faces formed in the first control face
and arranged circumferentially thereof, for receiving
the locking members in such a manner that the locking
members are held in the holding holes in a state in
which the locking members project from the inner
peripheral wall of the central bore of the arbor by a
second predetermined amount. The first control face and
the second control faces are arranged so that the
locking members selectively engage the first control
face and the second control faces. Upon connecting an
annular cutter to the arbor, locking member passing
means formed on the sidewall of the shank portion of the
annular cutter is passed through the regions of the
locking members, and the locking members engage with
recessed locking member receiving portions formed in or
at an end of the locking member passing means.
In order to achieve the second object of the
present invention, an annular cutter comprises a
substantially hollow cylindrical blade portion having
one end, a shank portion coaxially formed on the end of
the blade protion having a sidewall, locking member
-12-
pas~ing means formed on the sidewall of the shank
portion and depressed locking member receiving portions
formed in or on the locking member pACs~ ~ means and
arranged circumferentially thereof.
An ~n~t~ 1 ~r cutter connecting apparatus and an
annular cutter according to the present invention will
be described by way of preferred embodiments with
reference to Figs. 4 to 17.
First, the annular cutter connecting apparatus
according to the present invention will be described.
As shown in Figs. 4 and 5, a rotational speed and
a feed required for drilling operation is transmitted
from a dr~ ng machine (not shown) to an arbor 101
~onnected thereto. The arbor 101 is formed with a
cylindrical central bore 102 to which cutting oil is
supplied from the drilling machine through an oil
passage (not shown).
A seal member 103 is set in p'osition by a
ret~ n~ ng ring 104 in the lower portion of the central
bore 102. A valve body 105 for opening and closing oil
paths comprises a head portion 106, a flange portion
107 formed at the side of the seal member 103 and
formed with oil grooves 108 and a rod portion 109
coaxially extending downward from the flange portion
107 and idly fitted in the central hole 103a of the
seal member 103.
In the non-operative condition, the flange portion
__,
A
21~8581
_ -13-
107 is pressed against the seal member 103 by the
urging force of a compression coil spring 110 provided
in the central bore 102, thereby preventing the cutting
oil from leaking downward from the central hole 102.
The valve body 105, the seal member 103 and the
compression coil spring 110 constitute a valve for
opening and closing the oil paths.
During the drilling operation, the center pin 138
of each of annular cutters 130A, 130B, 130C and 130D
which will be described later in detail is pressed
against a workpiece and is lifted up. The head portion
139 formed on the upper end of the center pin 138 abuts
against the lower end of the rod portion 109 of the
valve body 105 and raises it. The flange portion 107
is separated from seal member 103 against the urging
force of the compression coil spring 110. As a result,
the cutting oil flows down through the oil passages
108, spaces formed between the flange potion 107 and
the seal member 103 and between the inner peripheral
surface of the central hole of the seal member 103 and
the outer peripheral surface of the rod portion 109 and
reaches the edges of the blade portion 131.
Holding holes 112 for receiving locking members
for fixing the annular cutter 130A (balls 113 in this
embodiment and hereinafter referred to as the "fixing
balls 113") are circumferentially arranged in the lower
end portion 111 of the arbor 101. Each holding hole
-14-
112 may have the same inner diameter throughout the
whole depth, but it is preferred that the inner-wall of
the holding hole 112 be tapered so that the diameter at
the inner end of the hole 112 i~ smaller than the
diameter at the outer end thereof. ~his prevents the
balls 113 from falling in the central bore 102 of the
arbor 101.
A substantially hollow cylindrical supporting
member 114 is A~lly slidably ~itted in the lower end
portion of the ~ ,al bore 102 and is urged downward
by the urging force o~ a comp~e~x~n coil spring 115
provided between the ~u~o~ng member 114 itself and
the ret~n1n~ ring 104. In the outer peripheral wall
of the lower end portion of the supporting member 114
is formed an ~nn~ r neck 116 having-a smaller outer
diameter than the rem~n~n~ part of the outer
peripheral wall, for receiving the fixing balls 113
which partially project from the holding holes 112
toward the central bore 102. The depth of the ~nnlll ~r
neck 116 is shown by E in Fig. 8.
The outer peripheral surface 117 of the lower end
portion 111 of the arbor 101 is reduced in diameter and
an ~nn~ r cutter fixing sleeve 118 is fitted thereon.
As shown in Figs. 6 and 7, the sleeve 118 comprises a
cylindrical first control face 119 defined by the inner
peripheral surface of the sleeve 118 and having an inner
diameter slidable over the outer diameter of the lower
-15-
portion 111 of the arbor 101, and second control ~aces
120 forming shallow U-shaped depressions arranged
circumferentially in the first control face 119. A
ring-~hap~ return spring chamber 121 formed in the end
of the sleeve 118 which end becomes the lower end of
the sleeve 118 when it is attached to the arbor 101.
In this embodiment, three second control faces 120 are
arranged circumferentially eguidistantly arranged in
the first control face 119. The number of the second
control faces is not limited to three. However, three
are the most suitable because the shank portion of the
annular cutter is supported most stably by the three
second control faces 120. The second control faces
120 may be circumferentially arranged at irregular
intervals, but it is preferable that they be arranged
regularly so that they receive equal loads.
The first control face 119 pushes the fixing balls
113 and causes parts of the fixing balls 113 to project
from the holding holes 112 deep into the central bore 102.
The sleeve 118 can be rotated in the direction of an arrow
A as shown in Fig. 8. In a non-operative condition, the
sleeve 118 assumes the rotated state in the direction of
the arrow A as shown in Fig. 8 by means of the a return
spring 124 as shown in Fig. 9. In this state, the fixing
balls 113 are in contact with the corresponding second
control faces 120 and are received by the neck portion
116 of the supporting member 114. Thus, they
A
-16-
are at the waiting position as shown in Fig. 4.
Referring to Figs. 4 and 5, the return spring
chamber 121 is covered with a ring cover 151 held on
the lower end of the outer peripheral wall of the arbor
101 by a holding ring 152.
As shown in Figs. 4 to 6 and 9, a substantially
C-shaped return spring 124 is housed in the return
spring chamber 121. One end 125 of the return spring
124 is fixed to the arbor 101 and the other end 126
thereof is fixed to the sleeve 118, and the sleeve 8 is
always urged in the direction of the arrow A in Fig. 8
so as to push the fixing balls 113 into the central
bore 102.
Next, embodiments of annular cutters according to
the present invention will be described.
Fig. 11 and 12 show a first embodiment of an
An~ r cutter 130A according to the present invention
which comprises a substantially hollow cylindrical
blade portion 131 having the open lower end and a
cylindrical shank portion 132A formed coaxially on its
upper end. On the lateral side of the shank portion
132A are formed flat faces 133 arranged circumferen-
tially at equal intervals. A recessed ball receiving
portion 134A forming a hemispherical depression for
receiving the respective fixing ball 113 is formed in
each flat face 133. The recessed ball receiving
portion 134A is an example of a locking member
'' 'A~ "
17-
receiving portion for connecting an annular cutter to
an arbor.
Fig. 13 is a transverse cross-sectional view
showing a second annular cutter 130B in a state in
which it is co~nected to the arbor 101. A cylindrical
shank portion 132B is coaxially formed on the upper end
of a blade portion 131 having the same structure of the
blade portion 131 of the first embodiment of the
annular cutter 130A, and flat faces 133 are formed on
the lateral side of the shank portion 132B in the same
manner as the flat faces 133 on the shank portion 132A
of the first embodiment of the annular cutter 130A. A
ball receiving portion 134B having a conical shape in a
horizontal cross section is formed in each flat face
lS 133. The ball receiving portion 134B is also an
example of the locking member receiving portion.
Figs. 14 and 15 show a third embodiment of an
annular cutter 130C of the present invention. Its
shank portion 132C has the same structure as the shank
portion 132A of the first embodiment of the annul ar
cutter 130A (the shank portion 132A having the
hemispherically recessed ball receiving portions 134A)
or the shank portion 132B of the second embodiment of
the annular cutter 130B (the shank portion 132B having
the conically recessed ball receiving portions 134B).
Another flat face lS3 is formed on the portion of the
outer peripheral surface of the shank portion 132C
, ~_
A~
8 ~ ~ ~
-18-
between ad~acent two flat faces 133. The flat face 153
is shown by broken lines in Figs. 4 and S. The other
structure is the same as that of the first and.e~co~A
embodiments of the ~nn~ r cutters 130A and 130B. The
annular cutter 130C can be co~ected to an arbor by
means of a conventional annular cutter connecting
apparatus by using the flat face 153 as a passing
portion.
Fig. 13 also shows a transverse cross section of
the third embodiment of the annular cutter 130C having
conically depressed ball receiving portions in a state
in which the annular cutter 130C is ~o~ected to the
arbor 101. The annular cutter, the shank portion and
the conically depressed ball receiving portions o~ the
third embodiment are shown by (130C), (132C) and
(134C), respectively, in Fig. 13.
Figs. 16 and 17 show a fourth embodiment of an
annular cutter 130D which has a blade portion 131 having
the same structure as that of the first embodiment of
the annular cutter 130A. A cylindrical guide portion
135 is coaxially formed on the upper end of the shank
portion 132D provided on the upper end of the blade
portion 131. The guide portion 135 has an outer
diameter reduced from the outer diameter of the shank
portion 132D so that it does not hit against the fixing
balls 113 when the shank portion 132D is inserted in
the central bore 102 of ~he arbor 101. Hemispherically
__.,.,,.. ~
~A~
--19--
recessed ball receiving portions 134D are formed
circumferentially in a step portion 136 defined between
the upper end of the shank portion 132D and the lower
end of the guide portion 135. The recessed ball
receiving portion 134D is also an example of the locking
member receiving portion.
In the embodiments described above, the flat faces
133 and guide portion 135 constitute locking member
p~ss~g means, and the locking member passing means and
10 the locking member receiving portions constitute
engaging portions.
The number, the positions and sizes of the flat
faces 133 of the annular cutter 130A and 130B, and the
guide portions 135 and the ball receiving portions
15 134A, 134B, 134C and 134D of the annular cutters 130C
and 130D correspond to the number, the positions and
the size of the fixing balls 18 when the shanks of the
annular cutter are fully inserted in the central bore
102 of the arbor 101 (Fig. 5). Because of this
20 arrangement, only the specific annular cutters 132A,
132B, 132C and 132D can be connected to the arbor 101
but other annular cutters cannot be connected thereto.
Each of the shank portions of the first to fourth
embodiments of the annular cutters has three ball
25 receiving portions arranged circumferentially
equidistantly. However, the shank portion may have a
polygonal cross section.
- ' -20~
As shown in Fig. 5, the center pin 138 for
setting a to-be-drilled position extends through the
center hole of the annular cutter 130A so as to be
movable axially. On the upper end of the center pin
S 138 is formed a head 139 having a larger outer diameter
than the outer diameter of the center pin 138 so as to
prevent the center pin 138 from slipping off the
central hole 137 of the annular cutter 130A. As
described above, the point formed on the lower end of
the center pin 138 abuts against a workpiece which is
being drilled, and the center pin 138 is lifted. The
valve body lOS for opening and closing the oil passage
is lifted by the head 139 of the center pin 138 to
allow the cutting oil in the arbor 101 to flow down to
the edges of the blades formed on the blade portion 131
of the annular cutter 130A. Each of the second to
fourth embodiments of the annular cutters 130B, 130C
and 130D is provided with a center pin having the same
structure as that of the first embodiment of the center
pin 138.
First, the processes of how to fix the annular
cutters to the arbors will be described.
The shank portion 132A of the annular cutter 130A
is inserted from below in the central bore 102 of the
arbor 101 which is in a state shown in Figs. 4 and 8.
As the shank portion 132A is inserted, the supporting
member 114 is lifted by the shank portion 132A and
'~'rA ~
2138581
-21-
disengaged from the fixing balls 113. The fixing balls
113 roll on the flat faces 133 and engage the ball
receiving portions 134A provided in the shank portion
132A at the final stage of the insertion. At the same
time, the sleeve 118 is rotated in the direction of the
arrow A in Fig. 8 by the urging force of the return
spring 124. As a result, the fixing balls 113 contact
the first control face 119 and are firmly pushed in the
ball receiving portions 134A. Thus, the annular cutter
130A is connected to the arbor 101 in one-touch
operation, as shown in Fig. 5.
Upon the connection of the first embodiment of the
annular cutter 130A to the arbor 101, the upper end of
the shank portion 132A reaches the region of the fixing
balls 113, as the shank portion 132A is inserted in the
central bore 102 of the arbor 101. When the flat faces
133 of the shank portion 132A are axially aligned with
the fixing balls 113, the fixing balls 113 engage the
ball receiving portions 134A by merely pushing the
annular cutter 130A in the central hole. When, on the
other hand, the flat faces are not axially aligned with
the fixing balls 113, the upper end of the shank
portion 132A hits against the fixing balls 113, and no
further insertion of the shank portion 132A is
permitted. However, after the flat faces 133 have been
aligned with the fixing balls 113 by rotating the
annular cutter 130A around its own axis, the annular
2138581
-22-
cutter 130A can be inserted further, enabling the
fixing balls 113 to be engaged with the ball receiving
portions 134A easily so that the connection of the
annular cutter 130A to the arbor 101 is completed.
The second and third embodiments of the annular
cutters 130B and 130C can be connected to the arbor 101
in the same way as the first embodiment of the annular
cuter 130A. As described above, the third embodiment
of the annular cutter 130C can be connected to the
arbor by means of a conventional annular cutter
connecting apparatus.
In an aligned state, the fourth embodiment of the
annular cutter 130D is fully inserted in the central
hole 102 of the arbor 101, and the balls 113 are fitted
in the ball receiving portions 134D, whereby the
annular cutter 130D is connected to the arbor 101. In
a misaligned state, however, the step portion 136 of
the shank portion 134D hits against the fixing balls
113, as the shank portion 134D is inserted in the
central bore 102 of the arbor 101. In this case, the
cutter 130D is rotated around its own axis to axially
align the receiving portions 134D with the fixing balls
113. Thereafter, the shank portion 132D is further
inserted in the central bore 102 of the arbor 101 so
that the fixing balls 113 engage the ball receiving
portions 134D. In this way, the annular cutter 130D is
connected to the arbor 101.
-23-
The three point support att~ne~ by the balls 113
of ~h~ first to fourth embodiment 130A, 130B, 130C and
130D ensures accurate transmission of the rotation and
t~he rotational force from the arbor 101 to the annular
cutters 130A, 130B, 130C and 130D and prevention of
center displacement between the annular cutter and the
arbor 101, le~1 ng to accurate drilling operation. The
reception of the balls 13 in the ball receiving
portions of the shank portion of the annular cutter
according to the present invention allows the annular
cutter to be moved slightly upward and downward
repeatedly due to the cutting resistance or the like
during the drilling operation so that cut chips are
broken into small pieces, the drilling efficiency is
improved and the life of the annular cutter is
prolonged.
As apparent from the above description, only an
annular cutter having locking member passing means
whose size and arrangement are suited for an annular
cutter co~necting apparatus which is now to be used can
be connected to an arbor, but an unsuitable annular
cutter is prevented from being connected thereto. Even
when long chips are produced and wound around the
sleeve 118 thereby lifting the sleeve 118, the sleeve
118 is not rotated in the direction in which the
annular cutter is released from the annular cutter
connecting apparatus. Thus, the annular cutter is not
.A r
-24-
loosened or removed by such chips from the arbor 101.
The annular cutter is removed from the arbor 101
in the following way.
The sleeve 118 of the annular cutter 130A is
m~nll~lly rotated in the direction opposite to the
direction of the arrow A in Fig. 8, and the second
control faces 120 are caused to face the fixing balls
113. Then, the annular cutter 130A is pushed downward
by the urging force of the compression coil spring 115
and automatically ~lips out of the arbor 101. Thus, the
removal of the annular cutter 130A from the arbor 101
can also be performed in one-touch operation, although
it is necessary to hold the annular cutter 130A during
its removal in order to avoid dropping of the annular
cutter 130A. As the annular cutter 130A is pushed out
of the arbor 101, the supporting member 114 is lowered
by the urging force of the compression coil spring 115,
and finally the fixing balls 113 are held by the
annular neck 116. In this way, the annular cutter
ro~ecting apparatus is returned to the original state
as shown in Fig. 4. The removing operation is
applicable to the other embodiments of the annular
cutters 130B, 130C and 130D.
..
A
