Note: Descriptions are shown in the official language in which they were submitted.
~2~
TOOL CHUC~
BAC~GROUND OF THE I~-E~TION
(1) Field of Application
This invention relates to tool chuchs for
attachment to power drills, power drivers and the
like, to hold tools such as drill bits and driver
bits, and more particularly to the type of tool chuck
that is manually tiohtened withcut using a chuck
handle.
(2) Description of the Prior Art
A conventional tool chuck of the type having a
turn ring rotatable with a chuck handle to extend and
retract chuck claws involves a cumbersome handle
. operation, maintenance of the chuck handle under care
1~ and other inconveniences. To eliminate such disadvan-
taoes, a tool chuck has already been developed which
has a turn ring rotated manually without using a chuck
handle to tiohten the chuck claws, and a locking
~ device for preventing the chuck claws from loosenino
durino an operation.
~-ith the tool chuck having such a locking device,
2028~1
however, the tool will rotate idlv to the detriment of
an effective operation if the chuck claws impart an
insufficient clamping force
In order to obtain a strong tightening force, it
is conceivable to increase the torque by reducing the
rotation of the turn ring throuoh a suitable reduction
mechanism Ho~ever, this would give rise to the
problem that the chuck cannot be operated quickly
since the chuck claws are caused to slide at a reduced
speed even when an inserted tool is not clamped by the
chuck claws.
OBJECTS OF THE INVENTION
A primary object of this invention is to provide
a tool chuck comprising a locking device disposed
1~ between a chuck bodv and chuck claws slidable by screw
feeding, the locking device pressing and locking to
the chuck body by a reaction force occurring when the
chuck claws clamp a tool, and a torque amplifying
de~-ice disposed between the locking device and a
control ring rotatably mounted on the chuck body, the
torque amplifyino device reducing rotation of the
- 202~
control ring to output an amplified torque to a screw
ring which screw-feeds the chuck claws when the lock-
ing device is locked to the chuck body, whereby the
chuck claws are slidable fast until the chuck claws
contact a tool inserted in position to realize a quicl;
clamping action.
.~ secondary object of this invention is to
provide a tool chuck wherein the rotation of the
control ring is provided with an automatically in-
creased torque when the chuck claws contact and hold
the tool, therebv causing the chuck claws to slide
~-ith the increased torque for holding the tool with a
strong clamping force.
Other objects of this invention will be apparent
1v from the following description of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DR~INGS
The drawings show embodiments of this invention,
in which:-
Fig. 1 is a view in vertical section of a tool
chuck in a first embodiment,
2028~01
Fig. '2 is an e~ploded perspective view of a
torque amplifving mechanism, and
Fig. 3 is a schematic view illustrating rolling
grooves,
Fig. ~ is a ~-iew in vertical section of a tool
chuck in a second embodiment,
Fig. 5 is a section taken on line I-I of Fig.
and illustrating an operation,
Fig. 6 is a section taken on line II-II of Fig.
and illustrating an operation,
Fig. 7 is a view in vertical section of a tool
chuck in a third embodiment,
Fig. 8 is a section taken on line III-III of Fig.
7,
Fig. 9 lS a view in vertical section of a tool
chuck in a fourth embodiment,
Fig. 10 is a view in vertical section of a
control ring,
Fig. 11 is a side view of the control ring,
Fig. 12 is a view in vertical section of a tool
chuck in a fifth embodiment,
Fig. 13 is an enlarged partial view in vertical
202~001
section of a torque amplifying mechanism in an
inoperative position,
Fig. 1~ is an enlar~ed partial view in vertical
section of the torque amplifyin~ mechanism in an
v operative position, and
Fig. 15 is an enlarged partial view in vertical
section of a tool chuck in a si~ embodiment.
DET~ILED DESCRIPTION OF THE PREFERRED E~BODI~IENTS
(First Embodiment)
A first embodiment of this invention will be
described in detail hereinafter with reference to the
drawings.
Figs. 1 through 3 show a tool chuck in the first
embodiment. This tool chuck is used with a power
1~ drill or a power driver for holding a tool such as a
drill bit or a driver bit.
Referring to Figs. 1 and 2, the tool chuck 10
comprises three chuc~ claws 1~ slidably mounted cen-
trallv of the forward end of a chuck body 11. The
chuck claws 12 are inclined with respective forward
ends thereof converging toward the a~is of the chuck
`- 202~0~1
bodv 11.
~ ore particularly, the chuck cla~is 12 are mounted
only slid~blv in slide arooves 13 formed in the chuck
body 11 as inclined relati~-e to its aYiS~ respective-
ly. Each claw 12 defines a partial male screw 1~ on aperipheral position thereof, with threads of the screw
arranged to constitute a continuous whole. The re-
spective partial male screws 1~ are meshed with a
female screw 16 ~efined in a screw rina 15. With
turnino of the screr~ rin~ 15 in opposite directions,
the chuck claws 1~ are slidable toward and away from
one another for clamping and releasing a tool.
A torque amplifying mechanism 17 is mounted
peripherally of t~le screw ring 15, and a control ring
18 is mounted peripherally of the torque amplifying
mechanism 17. When the control ring 18 is turned
forward or backward, i.e. in a direction to clamp or
release the tool A, the torque is transmitted to the
screw ring 15 through the torque amplifying mechanism
17.
The torque amplifving mechanism 17 is constructed
as follows.
20280Gl
The mechanism 1, includes three annular elements,
i.e. an output ring 20 press fit in and fi~ed to the
screw ring 1~, an input ring 21 relatively rotatably
supported in the control ring 18 and offset a prede-
termined amount of eccentricit~ e, and a locking ring22 movable into pressure contact with a rearward posi-
tion of the chuck body 11 through tapered peripheral
surfaces. These annular elements are arranged a~ially
of the chuc~ bod 11.
The input ring 21 defines a hypocycloidal rolling
groove 23 having an arcuate section on a surface
thereof opposed to the locking ring 22. The locking
ring 22 defines an epicvcloidal rolling groove 24
having arcuate sections on a surface thereof opposed
to the input ring 21. A plurality of balls 25 are
arranged between these rolling grooves 23 and 24 to
roll along the grooves 23 and 2~.
As also shown in Fig. 3, the rolling grooves 23
and 24 have an amplitude corresponding to the amount
of eccentricity e of the input ring 21. The input
ring 21 has ten waves, and the locking ring 22 twelve
waves. The number of balls 25 arranged therebetween
~ 2~12~0~L
is eleven or less.
~hen a revolution due to the amount of eccentric-
ity e is applied to the input ring 21 having the roll-
ing grooves 23 and 2~, the balls 25 roll along the
rolling grooves 23 and 24 to rotate the input rina 21.
Since the rotation is significantlv reduced with
respect to the revolution, the rotation of the input
ring 21 results in output of an amplified torque.
Since, in this embodiment, the rolling groove 23
of the input ring 21 has 10 waves and the rolling
groove 24 of the locking ring 22 has 12, the differ-
ence in the number of waves being 2, the reduction
ratio is 2/10 waves = 1/5.
A greater reduction ratio may be obtained by
increasing the numbers of waves. Where, for e~ample,
the input ring 21 has 40 waves and the difference in
the number of waves is 2, 2/40 waves = 1/20, to output
a greatly amplified torque.
To transmit the rotation of the input ring 21 to
the outpllt rin~ 20, a pluralitv of balls 26 are ar-
ranged between opposed surfaces thereof.
~ore particularly, the input rina 21 defines
202~01
recesses (not shown) for receiving the balls 26, while
the output ring 20 defines recesses 27 opposed there-
to. The recesses 2l of the output ring 20 have a size
(ring-shaped) for allowing the balls 26 to move round
5 b~- the same amount of eccentricity e, so that power
transmission is possible despite the eccentric turning
of the input ring 21.
For fixing the loc~ing ring 22 to the chuc~ body
11, the locking ring 22 defines, centrally thereof, a
tapered pressure contact surface 28 diverging rear-
wardly, while the chuck body 11 defines a pressure
contact surface 29 corresponding thereto. These sur-
faces move into pressure contact with each other when
the locking ring 22 is pushed by a backlash of the
screw ring 15 (with retraction of the chuck claws 1~),
whereby the lockino ring 22 is fi~ed to the chuck body
11 .
The locking ring 22 defines teeth 30 on the
circular rear end thereof. ~n elastic ring 33 is
disposed on the rear end of the locking ring 22, the
elastic ring 33 defining a plurality of elastic
elements 32 having pawls 31 elastically engaging the
2~GO~
teeth 30. The elastic ring 33 further defines fixing
bosses 3~ for press fitting into grooves 35 defined on
an inside wall of the control ring 18, whereby the
elastic ring 33 is retained in position and against
rotation.
The elastic elements 32 perform at least three
functions. One of them is application of an urging
force to separate the above-mentioned pressure contact
surfaces 28 and 29. The second function is to engage
the locking ring 22 and cause it to rotate with the
control ring 18 since, otherwise, the locking ring 22
would be freely rotatable when out of pressure contact
with the chuck body 11. The third function is a
locking function to fiY the locking ring 22 which may
become loose by reaction even when the locking ring 22
is pressed against the chuck body 11.
A cover 36 is mounted on the rear end of the
controi ring 18, and is press fit at a base thereof on
a rear position of the chuck body 11.
The elastic ring 33 is fixed to the control ring
18 in this embodiment, but may be fixed to the chuck
body 11.
-- 10 --
2028û01
..
The screw ring 15 consists of two parts which are
rigi~ly interconnected by the press fitting the output
rina 20 after the two parts are assembled to the chuck
bod~; 11. The interconnection may be achieved by any
other means, such as by defining screws on the two
elements for screwin tight together, or by a spline
engagement therebetween with an E-ring provided for
pre~-enting separation.
In Figs. 1 and 2, numeral 37 denotes a bearing
provided in the input ring 21 for smooth rotation of
the control ring 18.
The way in which the tool chuck 10 as constructed
above operates will be described ne~t.
Assume that the chuck claws 12 are wide open to
be ready to hold the tool A. The tool A is placed in
position, and the control ring 18 is turned in the
tightening direction for causing the chuck claws 12 to
clamp the tool A.
Since, in the initial stage of this ring turning
opera~ion, the chuck claws 12 are free from the load
resulting from the clamping of tool A, the locking
ring ~2 of the torque amplifying mechanism 17 is in a
2~28û~1
free state relative to the chuck body 11. Further,
since the locking ring 22 is engaged bv the elastic
elements 32, the output ring 20, input ring 21 and
locking ring 22 are interconnected as a unit and are
rotated to~ether. As a result, the rotation of the
control ring 18 directly causes an equal-rate rotation
of the screw ring 15, which provides a fast screw feed
for projecting the chuck claws 12.
A load acts on the chuck claws 12 when the claws
12 contact and begin to clamp the tool A. This load
causes a backlash of the screw ring 15, which rear-
wardly pushes the locking ring 22 through the output
ring 20 and input ring 21.
As a result, the pressure contact surfaces 28 and
29 of the locking ring 22 and chuck body 11 move into
pressure contact with each other. The elastic ele-
ments 32 vield to this pressure contact, which results
in slippage thereof. The locking ring 22 is then
fi~ed to the chuck body 11, to place the torque ampli-
fving mechanism 17 in an operable state.
That is, the rotation of the control ring 18
causes revol-ltion of the input rina 21, whereby the
- 12 -
~2~
.
balls 25 roll along the rolling grooves 23 and 2~ to
rotate the input ring 21. The rotation of the input
ring 21 is transmitted to the output ring 20 as a high
torque resulting from reduction of the input, to
5 rotate the screw ring 15 for projecting the chuc~
claws 12 and causin~ them to clamp the tool A with the
high torque.
In carrying out an operation with the tool A held
bv the chuck claws 12 as described above, the tool A
which may be a driver bit, for e~ample, is turned in
opposite directions depending on the nature of the
operation.
If this operation involves forward rotation of
the tool A which acts on the control ring 18, torque
amplifying mechanism 17 and screw ring 1~ in the
direction to tighten the chuck claws 12, then backward
rotation acts on these components 18, 17 and 15 in the
direction to rela~ the chuck claws 12. Even though a
reaction occurs with reversal of the rotation acting
in the direction to rela~ the chuck claws 12, actually
no rela~ation will occur because the locking ring 22
is engaged by the elastic elements 32 to rigidlv
20~a~
.
connect the control ring 18, torque amplifying mecha-
nism 17 and screw ring 15 to the chuck body 11.
When releasing the tool A, the control ring 18
needs onlv to be rotated in the rela~ing direction.
Then the chuck claws 12 are rela.Yed under a high
torque since the torque amplifying mechanism 17 is in
the operative state in the initial stage of rotation.
~hen the chuck claws 12 are further rela~ed to elimi-
nate the backlash of the screw ring 15, the elastic
elements 32 push back the lockino ring 22. Conse-
quently, the pressure contact surfaces 28 and 29 of
the locl~ing ring 22 and chuck body 11 move out of the
pressure contact. The screw ring 15 rotates fast at
the same speed as the control ring 18, to move the
chuck cla~-s 12 fast in the rela~ing direction.
According to this embodiment, the tool ~ is held
with the tightening force amplified by the torque
amplifying mechanism 17. Thus the tool A is held
ri~idly in a manner equivalent to the case of using a
chuch handle.
Further, the torque amplifying mechanism 17
includes the three rings, i.e. the output ring 20,
- 2028001
input ring ~1 and locking ring 22. This construction
is compact and capable of easily interlockind with the
chuck claws 12. Despite the simple construction, a
great torque can be transmitted.
The urging engagement provided by the elastic
elements 32 is effective to prevent loosening of the
control ring 18 and chuck claws 12 against vibrations
occurring during an operation. This promotes clamping
of the tool A with increased rigiditv.
Besides the function to pre~-ent relaxation, the
elastic elements 32 have the functions to engage the
control ring 18 for ri~id connection, to retain the
control ring 18 on the chucl. body 11, and to release
the chuck body 11 and chuch claws 12 from mutual
pressure contact when removing the tool A from the
chuck claws 12. This single component fulfilling
these functions enables the construction to be compact
with a reduced number of components.
In the foreaoing first embodiment, the output of
input ring 21 is transmitted to the screw ring 15
througll the output ring 20. Alternatively, the output
may be made through a gear coupling operatively inter-
- 15 -
2D~8û~1
connectina the input ring 21 and screw ring 15 and
capable of absorbing the eccentric rotation of the
input ring 21.
Further, in the first embodiment, the chuck claws
12 are fed by the action of screw ring 1~ fitted
peripherally thereof. The torque amplifyina mechanism
1/ is applicable to the type of chuck claws which are
pushed and pulled by a bush provided at the rear ends
of the chuck claws and driven by screw feeding.
(Second Embodiment)
Figs. 4 through 6 show a tool chuck in a second
embodiment. In Fi8. 4, the tool chuck 40 comprises
three chuck claws 42 slidably mounted in a chuck body
41, to be projectable and retractable by opposite
rotations of a screw ring ~3, as in the first embodi-
ment shown in Fig. 1. A detailed description of such
arrangement i5 omitted here.
The screw ring 43 consists cf two parts which are
rigidly interconnected by press-fitting a sleeve 44
peripherally thereof.
The chuck body 41 carries a cylindrical control
ring 45 rotatablv mounted on an intermediate peripher-
- 16 -
2028001
al position thereof. A cylindrical co~er ~6 is fitted
and fiYed to the periphery at a pro~imal end of the
chuck body ~1.
A torque amplifying mechanism 47 is pro~ided in a
power transmitting path between the scre~- rino 43 and
control rin~ 45 for transmitting torque of the control
ring ~5 to the screw ring ~3.
The torque amplifying mechanism 47 includes an
input/output ring ~8 rotatabl~ fitted in the control
ring 48, and a lockin~ rin~ 4g rotatablv mounted on
the chuck body 41.
The input/output ring ~8 has a forward inside
~-all fitted through a needle bearing 50 on the outer
peripheral surface of a tubular control section 51
formed centrally of the control ring 45.
As also shown in Fia. 5, the outer peripheral
surface of the tubular control section 51 is formed
about an a~is C which is offset an amount e with
respect to an a.~;is B of the chuck body ~1.
The input/output ring 48 has an intermediate
inside wall in drivin~ en~a~ement throuah a gear
couplin~ 52 ~iith an outer periphery of a rear end of
20280~1
the screh ring ~3.
~ lore particularl~, this gear coupling 52 is
loosel-- meshed ~-ith a gear 53 formed on the inter-
mediate inside wall of the input/output ring ~8, and
5 h-ith a ge2r 5~ formed on the outer periphery at the
rear end of the screw ring ~3, to allow eccentricitv
in the amouni e.
Further, the input/output ring ~8 has a rear
inside wall defining a gear 55 which, as also shown in
Fig. 6, is meshed with a gear 56 formed peripherally
of the locking ring ~9.
These gears 55 and 56 form cycloidal gears for
making a ccloidal motion. When the control ring ~5
is turned to revolve the input/output ring 48 through
the eccentricit~ of the tubular control section 51, a
difference in the number of teeth between the gear ~5
formed on the input/output ring 48 and the gear 56
formed on the locking ring 49 results in rotation of
the input/output ring ~8 corresponding to the e~tra
number of teeth. As a result, the rotation of the
input/output ring ~8 is greatly reduced, and the rota-
tion of the input/output ring 48 pro~-ides an amplified
- 18 -
2028001
torque output.
~ here, for e.~ample, the gear 56 of the locking
ring ~9 has 66 teeth and the gear 55 of the input/out-
put rin~ ~3 has 68, the difference in the number of
teeth being 2, the reduction ratio is 2/66 teeth =
1/33. Thus, the reduction ratio of 1/33 is obtained
with respect to an input, whereby the input/output
ring ~8 provides a greatly amplified torque output.
A suitable number of thrust balls are mounted for
rolling movement between opposed surfaces of the screw
ring ~3 and locking ring 49.
The locking ring 49 has an inside peripheral wall
defining a tapered pressure contact surface 58 diverg-
ing rearwardlv, ~hile the chuck body 41 has an inter-
mediate outer peripheral wall defining a taperedpressure contact surface 59 opposed to the contact
surface 58 and divergina rearwardl~, to correspond
thereto.
These pressure contact surfaces 58 and ~9 move
~0 into pressure contact with each other when the screw
ring 43 is retracted by a backlash of the chuck claws
~2 resultin~ from tightening of the screw ring 43 for
-- 19 --
2028~
clamping the tool A, whereby the lockina rino 49 is
fi~ed to the chuck body ~1.
An elastic ring 60 is fitted in a peripheral
inside wall of the control ring ~ to be opposed to
5 the rear end of the locking rin~ ~9. The elastic ring
60 incl~des elastic elements 61 formed around inside
peripheral positions thereof and engaging a toothed
surface at the end of the locking ring ~9. In this
~-av, the control ring 45 and lockina ring ~9 are
ri~idly interconnected and the lockina ring ~9 and
chuck body ~1 are urged in a direction to separate the
pressure contact surfaces 53 and 59.
A retainer ring 63 is fi~ed by press fit rear-
wardly of the elastic ring 60 to hold the elastic ring
60 in positicn and against rotation.
The way in which the tool chuck ~0 as constructed
according to the second embodiment is tightened and
loosened will be described ne.Yt.
~ hen the tool A is clamped by the three chuck
claws ~2, the control ring ~5 is turned in a tighten-
ino direction D (indicated by solid line arrows in
Fias. 5 and 6~ for clamping the tool A, with the co-~er
- 20 -
202~001
~6 locked aaainst rotation.
Since, in the initial staoe of this turning
operation, the chuck claws ~2 are free from the load
resulting from the clamping of tool A, the lockino
5 ring ~9 forming part of the torque amplifying mecha-
nism ~, is rotatable relative to the chuck body ~1.
F~lrther, since the locking ring 49 is connected to the
control ring ~5 by the elastic elements 61, the
control ring 45, input/output ring ~8 and locking ring
lg rotate to~ether. As a result, the rotation of the
control ring ~5 directly causes an equal-rate rotation
O,r the screw ring ~3, which provides a fast screw feed
for rapidly projecting the chuck claws 42 to clamp the
tool ~.
Subsequently, a load acts on the chuck claws ~2
when the claws 42 contact and begin to clamp the tool
. Then the screw ring ~3 is retracted by a backlash
due to the tightenin~, which rearwardly pushes the
locking ring ~9 through the thrust balls 5/. As a
result, the pressure contact surfaces 58 and 59 of the
locking ring ~9 and chuck body 41 move into pressure
contact with each other. The elastic elements 62
- ` 2~280~1
yield to this pressure contact, which results in slip-
page thereof. The locl.ing ring 49 is then fi~ed to
the chuck body ~1, to place the torque amplifying
mechanism ~l in an operable state to produce the speed
reducing effect.
That is, the rotation of the control ring 45
causes the tubular control section 5l to revolve the
input/output ring ~8 the amount of eccentricity. This
produces rotation of the input/output ring 48 based on
the difference in the number of teeth between the gear
55 formed on the input/output ring 48 and the gear 56
formed on the locking ring 49. This rotation is
output as a high torque resulting from reduction of
the input, to rotate the screw ring 43 and screw-feed
the chuck claws 42, therebv causing them to clamp the
tool A with the high torque.
In carrying out an operation with the tool A held
by the chuck claws ~2 as described above, the elastic
elements 61 engaging the locking ring ~9 act to stop
the rela.~ation resulting from rotation in the direc-
tion to relav~ the chuck claws 42.
~ihen releasing the tool A, the control ring ~5
- 22 -
202~001
needs only to be rotated in the rela~ing direction E
(indicated by dotted arrows in Figs. 5 and 6).
When the chuc~ claws 42 are retracted to elimi-
nate the backlash due to the tightening and actina on
the screw ring ~3, the locking ring ~9 is advanced by
the urging force of elastic elements 51. Consequent-
ly, the pressure contact surfaces 58 and 5~ of the
locking ring ~9 and chuck body 4l move out of the
pressure contact. Then the reduction effect of the
torque amplifying mechanism ~ is canceled, whereby
the control rino ~5, input/output ring ~8 and loc~ing
ring ~g rotate to~ether. The screw ring ~3 rotates at
the same speed as the control ring ~, to screw-feed
the chuck cla~s ~2 fast in the rela~ing direction. As
1~ a result, the chuc~ claws ~2 rapidl~- slide away from
each other to release the tool A.
~ hen the tool A is held, the torque undergoes the
speed red~lction and amplification by the torque ampli-
f~-ing mechanism ~l as described above. Thus, a higher
torque is obtained than where the torque of the con-
trol ring 4~ is transmitted directly to the screw ring
43 meshed with the respecti~e chucl claws 4 . By
2028031
simply turning the control ring ~5 in the tightening
direction, the tool ~ may be rigidly clamped and fi~ed
in position.
~oreover, the control rino ~5, input/output ring
5 ~8 and lockino, ring ~9 may be rotated together in
opposite directions during the turning operation
carried out until the tool A is clamped in position
and the turning operation after the release thereof.
The chuc~ claws ~2 are rapidly screw-fed toward and
away from one another by the screw ring ~3 to clamp
and release the tool A. Thus, this construction has
e~cellent operability.
The following construction may be provided in
place of the tubular control section 51 of the second
embodiment.
The control ring ~5 may have an inside peripheral
~-all offset the amount e with respect to the a~is B of
the chuck bodv ~1, with the input/output ring ~8
loosely fitted in this eccentric inside peripheral
wall, the input/output ring ~8 being revolvable along
the eccentric inside peripheral wall of the control
ring ~5.
- 2~ -
- 202~
Such a construction will be described ne~t as a
third embodiment, with emp~asis placed on the torque
amplifying mechanism.
(Third Embodiment)
Figs. 7 and 8 show a tool chuc~ in the third
embodiment. This tool chuck has the same basic
construction as in the second embodiment, and like
components are affixed with like reference numerals
~-ithout describing the particulars thereof.
The control ring 45 has an inside peripheral wall
formed about an a~is C which is offset an amount e
with respect to the a.~is B of the chuck body 41. The
input/output ring 48 of the torque amplifying mecha-
nism ~7 is rotatably fitted in the concentric inside
1~ peripheral wall 70 of the control rino ~8 through a
plurality of balls 71. When the control ring ~5 is
turned, the input/output ring ~8 is revolvable along
this eccentric peripheral inside wall 70.
A sleeve 72 is press fitted peripher~llv of the
screw ring 43. The gear coupling 52 comprises a gear
53 formed on an inside wall at the forward end of the
input/output ring 48 and a gear 54 formei on the outer
- 2~ -
2028001
periphery of the slee~-e 5~.
~ urther, the input/output ring 48 has a rear
inside wall defining a gear ~5 which is meshed with a
gear 56 formed peripherallv of the locking rin, ~9.
These gears 55 and 56 form cvcloidal gears. The
numbers of teeth of these gears 55 and 56 are selected
as in the second embodiment.
When the control ring 45 is turned, the torque
amplifying mechanism 47 causes the tool A to be
clamped as in the second embodiment.
In the initial stage of this turning operation
when the chuck claws ~2 are not clamping the tool A
yet, the control ring 45, input/output rino 48 and
locking ring 49 rotate together to rotate the screw
1~ ring 43 at the same speed as the control ring 45 as
described in the second embodiment. The fast screw
feed by the screw rino 43 causes the chuck claws 42 to
mc~-e toward one another rapidly to clamp the tool A.
Subsequently, a load acts on the screw ring 43
when the chuck claws 42 contact and begin to clamp the
tool A. Then the screw ring 43 is retracted by a
backlash due to the tightening, which rearwardly
2028~01
pushes the loc~ing rin~ 49 through the thrust balls
5~. As a result, the pressure contact surfaces 58 and
59 of the locking ring 49 and chuc~ body 41 move into
pressure contact with each other. The elastic ele-
5 ments 62 yield to this pressure contact, which resultsin slippage thereof. The locking ring 49 is then
fi~ed to the chuck body ~1, to place the torque ampli-
f~;ing mechanism 47 in an operable state to produce the
speed reducing effect.
10That is, the rotation of the control rin~ 46
causes the eccentric inside wall 70 to revolve the
input/output ring 48 the amount of eccentricity. This
produces rotation of the input/output ring 48 based on
the difference in the number of teeth between the gear
1555 formed on the input/output rin~ ~8 and the gear 56
formed on the locking ring 49. This rotation is out-
put as a high torque resulting from reduction of the
input, to rotate the screw ring 43 through the gear
couplina 5Z and screw-feed the chuck claws 42, thereby
causing the chuck claws 4~ to clamp the tool A with
the high torque.
When releasing the tool A, the control rin~ 45
2028001
needs only to be rotated in the rela~ing direction E
(indicated by the dotted arrow in Fig 8), as already
described in the second embodiment. A detailed
description thereof will therefore be omitted.
Functions and advantages may be expected from the
third embodiment as constructed above, which are equi-
~-alent to those of the second embodiment.
(Fourth Embodiment)
Fi~s. g, 10 and 11 show a tool chuck in a fourth
embodiment. This fourth embodiment relates to another
e~ample of the bearing for the input/output ring 48 in
the third embodiment. The torque amplifying mechanism
~, and other basic constructions are the same as in
the third embodiment, and like components are affixed
1~ with like reference numerals without describing the
particulars thereof.
As in the third embodiment, the control rin~ 4~
has an inside peripheral wall offset with respect to
the axis of the chuck body ~1. The input/output rina
48 of the torque amplifying mechanism 47 is rotatably
fitted in the concentric inside peripheral wall 70 of
the control ring 48. When the control ring ~ is
- 2~ -
-
2028~)01
turned, the inpu./o-ltput ring ~8 is revolvable along
this eccentric peripheral inside wall 70.
The input/output ring 48 revolvable as above is
supported by a plurality of needle bearings ~. These
5 needle bearings 7~ are arranged only along a partial
circumferential range.
That is, the cycloidal gear 56 of the loc~ing
ring ~g revolves and rotates while partiallv engaging
the cycloidal gear 55 of the input/output ring ~8.
This engagement takes place in a fi~ed range as far as
the control ring 45 is concerned. The load produced
by clamping of the tool A results in a radial pressure
acting only in the above ranae of engagement.
Thus, the needle bearings 7~ are provided along
the partial circumferential range of the control ring
~5 where the gears 55 and 56 engage each other and the
load is applied.
The needle bearings 7~ have ends slightly proj-
ecting to~ard the locking ring ~9. The locking ring
~9 defines a fittino groove 75 e~tending circumferen-
tiallv therecf and opposed to the projecting portions
of the needle bearings 7~. This fitting groove 7
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20280~1
receives the projecting portions of the needle bear-
ings 7~ so as to allow mo~-ement due to the rotation
(movement relative to the locking ring ~9) of the
needle bearings 7~.
The load produced by the clamping of the tool A
acts on the needle bearings 7~ and radiallv presses
the needle bearings 7~ as noted above. Therefore,
where the control ring ~6 is formed of a synthetic
resin, the pressing force will tend to partially
e~pand and deform the control ring ~5. Such outward
deformation of the control ring ~5 is suppressed since
the ends of the needle bearings 7~ are snugly fitted
in the fitting groove 75 against out~-ard spread under
the pressure.
1~ ~hen the control ring ~5 is outwardlv e~panded,
this will fill the gap between its outer periphery and
the cover ~6, which is effective to prevent entry of
dust and other foreign matter through the gap.
~hen the force is applied to radially spread the
needle bearings 7~ as noted above, this load is
appLied to the inward position of the control ring ~.
~s a result, an internal stress is produced in the
- 30 -
2028001
control ring ~ to cause a twist with its outward
portion.
To counteract the twist, needle bearin~s 76 are
pro~-ided on an inside peripheral wall in the outward
portion of the control ring ~5 to be opposed to the
needle bearings ~. These needle bearings 16 prevent
the twist of the control ring ~5.
The needle bearin~s 74 and 76 may be provided in
a small number. ~ith the projecting portions of the
needle bearings 7~ held in the fitting groove 76 of
the locking ring ~9, the deformation of the control
ring ~5 due to the tool clamping load may be avoided.
The bearing structure described above may be
applied also to the tool chuc~ in the first embodiment
shown in Fia, 1.
In Fig. 9, the elastic rin~ 60 comprises a spring
material formed into an inclined flange shape and
retaining a plurality of balls 7~ at a pluralit~- of
positions thereof. These balls ~1 engage and spring-
load the toothed face 62 e.~tending over the entireperiphery of the locl~ing ring ~9.
The elastic ring 60 thus formed provides func-
.
2o`28QDI
tions and ad~antages equivalent to those provided bythe third embodiment.
In Fig. 11, recesses 78 serve to lock the elastic
ring 60, and the latter defines projections (not
shown) engageable with these recesses.
(Fifth Embodiment)
Figs. 12, 13 and 14 show a tool chuck in a fifth
embodiment. In Fig. 12, the tool chucl~ 100 comprises
three chuc~ claws 102 slidably mounted in a chuck body
101, to be projectable and retractable by opposite
rotations of a screw ring 103, as in the first embodi-
ment sho~in in Fig. 1. A detailed description of such
arrangement is omitted here.
The screw ring 103 consists of two parts which
1~ are rigidly interconnected by press-fitting a sleeve
10~ peripherally thereof.
A cover 105 having a U-shaped section is fi:~ed to
the outer periphery of a pro~imal end of the chuck
body 101. The chuck body 101 carries a cylindrical
control ring 106 rotatably mounted on an intermediate
peripheral position thereof. The control ring 106 has
the o--ter periphery of an open end thereof relatively
- 32 -
~. 2o28ool
rotatabl~- fitted in the inner periphery of the pro~i-
mal end of the cover 10~.
A torque amplifying mechanism 10/ is provided
bet~ieen the control ring 106 and screw ring 103 for
transmittino torque of the control ring 106 to the
screw ring 103.
The torque amplify-ing mechanism 10/ includes an
input ring 108 interlocked with the control ring 108,
an output retainer 112 fi~ed to the screw ring 103,
and a locking ring 115.
The input ring 108 is rotatably mounted on an
intermediate outer periphery of the screw ring 103. A
plurality of metallic rolling balls 109 are arranged
between opposed surfaces of the input ring 108 and
1~ sleeve 10~. The input ring 108 includes a plurality
of projections 110 on the outer periphery thereof for
engagement with a plurality of grooves 111 defined in
the inside wall of the control ring 106. In this way,
the input ring 108 is interlocked with the control
ring 106 to be capable of a slight a~ial movement.
The output retainer 112 is fi~ed to the outer
perlphery of a pro~imal portion of the screw ring 103.
- 33 -
202~01
The output retainer 112 includes ball holders 113
provided at, for example, 16 equidistant positions
peripherally thereof. Each ball holder 113 holds a
metallic ball 11~.
The locking ring 115 is rotatably supported
between the output retainer 112 fixed to the screw
~ing 103, and a stepped portion defined on an inter-
mediate periphery of the chuck body 101. The locking
ring 115 is constantly urged for pressure contact with
the balls 11~ of the output retainer 112 fi~ed to the
screw ring 103, by a coil spring 116 housed in the
proximal portion of the cover 105.
The coil spring 116 is compressed between a
sprinG stopper 11, fixed to the inside wall of the
proximal portion of the cover 105 and a presser plate
118. A plurality of metallic balls 119 are arranaed
between opposed s-lrfaces of the locking ring 115 and
pressure plate 118.
Thus, the coil spring 116 constantly presses the
presser plate 118, balls 119, locking ring 115, the
balls 11~ held bv the output retainer 112, input ring
10~, balls 109, sleeve 10~ and screw ring 103 a~ially
~ 202800I
against a peripher~l inside wall at a forward end of
the control rina 106.
.~s shown in Fig. 13, a leaf spring 121 is fi~ed
to the inside wall of the control rin~ 106 and opposed
to the outer periphery of the loc~ino ring 115. When
the locl.{ing rino 11~ is permitted to rotate in oppo-
site directions, a projection 122 formed on the leaf
spring 12i en~ages a toothed surface 123 formed on the
outer periphery of the locking ring 115 to rotate the
locking ring 115 in the same direction as the control
rin~ 106. ~hen the locking ring 115 is locked aoainst
rotation, this en~agement is broken to allow rotation
of the control ring 10~ only.
The engaging arrangement between the projection
122 of leaf spring 121 and the toothed surface 123 is
equivalent and performs a similar function to the
arrangement between the toothed surface 30 and elastic
elements 32 in the first embodiment shown in Fig. 3.
However, the leaf spring 121 does not act to separate
the loc~ing ring 115 from the stepped portion 120, and
the fifth embodiment relies for this function on the
coil spring 116.
- 35 -
2028~01
The lccking ring 11~ includes a pressure contact
surface 1~ on an inside periphery thereof for pres-
sure contact with the stepped portion 120. This pres-
sure contact surface 12~ may have a tapered shape.
The wa~- in which the tool chuck 100 as con-
structed according to the fifth embodiment operates to
clamp the tool A will be described ne~t.
First, the tool A is inserted into the chuck body
101 through the chuck claws 102 kept wide open. Then
the control rino 106 is turned in a tool clamping
direction relative to the chuck body 101.
During the turning operation before the chuck
claws 102 move into contact with the tool A, only a
minor recistance is applied to the screw ring 103, and
1~ the loc~ing ring 11~ of the torque amplifying mecha-
nism 107 is in a free state relative to the chuck body
101. Further, since the locking ring 11~ is connected
to the control ring 106 by the leaf sprin~ 121, the
control ring 106, input ring 10~, balls 11~ of the
output retainer 112, and locking ring 11~ rotate to-
gether. The rotation of the screw ring 103 which is
at the same speed as the control ring 106 provides a
- 36 -
202gO~l
fast scre~ feed for rapidlv projecting the chuck cla~s
102 to clamp the tool A.
Subsequentlv, as shown in Fig. 1~, a load acts on
the chuck claws 102 when the claws 10 contact and
begin to clamp the tool A, therebv producing a back-
lash of the chuch claws lOZ. Then the screw ring 103
is a~ially retracted by the backlash, which a,~ially
retracts, through the sleeve 10~ and balls 109, the
input ring 108, balls 11~ held by the output retainer
11~, and locking rin~ 115 of the torque amplifying
mechanism 10l which have been axially pressed. As a
result, the pressure contact surface 124 of the locl,-
ing ring 115 moves-into pressure contact with the
stepped portion 120 of the chuck body 101, and the
leaf sprin,g 121 for locking the locking ring 115
against rotation undergoes slippage.
W'hen the locking ring 115 is locked against
rotation, the balls 11~ of the output retainer 112 act
~s i~lers to roll, with the rotation of the input ring
108, along the opposed face of the locking rina 115.
This rolling movement pro~-ides a reduced rotation of
the output retainer 112, which reduces the rotation of
3t -
-
202~01
the control ring lU6 to rotate the screw ring 103 with
high torque, thereby causing the chuck claws 102 to
firml~J clamp the tool A.
In carr~ing out an operation with the tool A, the
leaf sprino 121 providing the locking engagement acts
to stop rela~ation due to reactions of opposite rota-
tions of the tool chuck 100, which is the same as in
the preceding embodiments.
When releasing the tool A, the control ring 106
is turned in the relaYing direction relative to the
chuck bod-~ 101. In the initial stage of the turning
operation, a momentarv high torque occurs since the
locking ring 115 of the torque amplifying mechanism
10l is locked against rotation. This facilitates
rotation of the screw ring 103 in th~ rela~ing direc-
tion.
Once rela~Yed, the resistance to the rotation
diminishes, and the coil spring 116 releases the lock-
ing ring 115 from the pressure contact, with the lock-
ing ring 11~ connected to the control ring 106 through
the leaf spring 121. Then, the control ring 106 and
torque amplifying mechanism 107 rotate together. The
- 38 -
2`o2~oDl
rotation of the control ring 106 causes the screw ring
103 to rotate at the same speed, whereby the chuck
claws 102 rapidly slide away from each other to
release the tool A.
When the tool A is held, as described above, the
rotation of the control ring 106 is reduced by the
rotating balls 11~ forming part of the torque ampli-
fying mechanism 107, for transmission to the output
retainer 11~. Thus, a higher torque is obtained than
the torque for rotatin~ the control ring 106, for the
tool A to be clamped firmly.
Moreover, the resistance of the load is small,
and the control ring 106 and the respective components
of the torque amplifying mechanism 107 can rotate
1~ together in opposite directions by the action of leaf
spring 121 during the turning operation carried out
until the tool .~ is clamped in position and the turn-
ing operation after the release thereof. The chuck
claws 102 are rapidly screw-fed toward and away from
one another by the screw ring 103 to clamp and release
the tool A. Thus, this construction has e~cellent
operabilitv,
- 39 -
20280~I
For facility of operation, the relative rotation
between the chuck body 101 and control ring 106 may be
effected by opposite rotations of the power drill or
power driver to which the ch-~ck bodv 101 is attached.
This applies to the other embodiments as well.
In the fifth embodiment, the torque amplifying
mechanism 107 includes the balls 11~ rotatable to
cause reduced rotation of the output retainer 112.
These balls 114 may be replaced bv gears.
Such a construc-tion will be described as a si~th
embodiment next.
(Si~th Embodiment)
Fig. 1~ shows a tool chuck in the si~th embodi-
ment. This tool chuc~ has the same basic construction
as in the fifth embodiment, and like components are
affixed with like reference numerals without describ-
ing the particulars thereof.
As illustrated, the torque amplifying mechanism
10, includes a plurality of bevel gears 12~ provided
between the screw ring 103 and output retainer 112
fi~ed thereto. The bevel gears 125 are meshed with a
gear surface 126 formed on the input ring 108 and a
-- ~0 --
'_, , 2028~1
ge~r surface 1 ~ formed on the locking ring 115,
respectivel~-.
With this construction, when the locking rina 115
is locked against rotation by the pressure contact
5 with the stepped portion 120, rotation of the input
ring 108 causes rotation and rolling movement of the
be~-el g~ars 125. The rotation of the control ring 106
is reduce~ b~,r this rolling movement for transmission
to the OUtp-lt retainer 112. Thus, the bevel gears 11~
perform a function equivalent to that of the balls 114
in the fifth embodiment, and this construction pro-
vides a high torque as in the fourth embodiment.
-- ~1 --
