CA1087885A - Electrically powered torque-controlled tool - Google Patents
Electrically powered torque-controlled toolInfo
- Publication number
- CA1087885A CA1087885A CA302,910A CA302910A CA1087885A CA 1087885 A CA1087885 A CA 1087885A CA 302910 A CA302910 A CA 302910A CA 1087885 A CA1087885 A CA 1087885A
- Authority
- CA
- Canada
- Prior art keywords
- torque
- electric motor
- bit
- cut
- clutch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
- B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
- B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T292/00—Closure fasteners
- Y10T292/08—Bolts
- Y10T292/096—Sliding
- Y10T292/1014—Operating means
- Y10T292/1022—Rigid
- Y10T292/1028—Sliding catch
Abstract
TITLE OF THE INVENTION
ELECTRICALLY POWERED TORQUE-CONTROLLED TOOL
ABSTRACT OF THE DISCLOSURE
An electrically powered torque-controlled tool having an electric motor which rotates a bit, whereby a screw, bolt or nut fitted at the front and of the bit is tightened. The tool is designed so that when the tighten-ing force exerted by the bit reaches a preset torque, the driving by the electric motor is stopped by opening the switch and concurrently therewith a clutch interposed between the electric motor and the bit is disengaged and held in this released state, thereby avoiding the reaction which would otherwise be produced by the motor inertia immediately after the tightening, thus achieving a high-precision tightening operation.
ELECTRICALLY POWERED TORQUE-CONTROLLED TOOL
ABSTRACT OF THE DISCLOSURE
An electrically powered torque-controlled tool having an electric motor which rotates a bit, whereby a screw, bolt or nut fitted at the front and of the bit is tightened. The tool is designed so that when the tighten-ing force exerted by the bit reaches a preset torque, the driving by the electric motor is stopped by opening the switch and concurrently therewith a clutch interposed between the electric motor and the bit is disengaged and held in this released state, thereby avoiding the reaction which would otherwise be produced by the motor inertia immediately after the tightening, thus achieving a high-precision tightening operation.
Description
lOB78B5 The present lnvention relates to an electrically powered torque-controlled tool used, for example, for tightening threaded parts, such as bolts and nuts with the proper torque to avoid the deterioration Or product~
due to excessive or deficient tightening and make it easier for the tightening worker to control torque, thereby improving the ef~iciency of operation in a~sembling variou~ parts and products. More particularly, the invention relates to an electric~lly powered torque-controlled tool /0 which emplo~s an electric motor as a drive 30urce ~o that it can be easily used even in terminal factories where there is no air equipmant,said tool being ~ree from factors unde~irable to working e~vironment, ~uch as noi~e and vibration.
Further, the invention may be utilized as a safet~
device in connection with other electrically powered rotatory tools in order to ~top the electric motor when a preset torque is attained.
Recently, in electrically powered torque-controIled c~ tool~, especially electrically powered screw drivers~
there ha~ been an increa~ing demand for driving screw~ into synthetic resin products which require tightening-torque control, and in con~unction therewith electrically powered screw drivers which are electrically controlled ha~e come to be spoblighted, but such prior art electrically powered screw drivers are designed merely to ~top the electric motor, with the result that it ha~ been impossible to aYold the reaction to the worker' 5 hands produced upon ~,
due to excessive or deficient tightening and make it easier for the tightening worker to control torque, thereby improving the ef~iciency of operation in a~sembling variou~ parts and products. More particularly, the invention relates to an electric~lly powered torque-controlled tool /0 which emplo~s an electric motor as a drive 30urce ~o that it can be easily used even in terminal factories where there is no air equipmant,said tool being ~ree from factors unde~irable to working e~vironment, ~uch as noi~e and vibration.
Further, the invention may be utilized as a safet~
device in connection with other electrically powered rotatory tools in order to ~top the electric motor when a preset torque is attained.
Recently, in electrically powered torque-controIled c~ tool~, especially electrically powered screw drivers~
there ha~ been an increa~ing demand for driving screw~ into synthetic resin products which require tightening-torque control, and in con~unction therewith electrically powered screw drivers which are electrically controlled ha~e come to be spoblighted, but such prior art electrically powered screw drivers are designed merely to ~top the electric motor, with the result that it ha~ been impossible to aYold the reaction to the worker' 5 hands produced upon ~,
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' ~L~878B5 the ~toppage of the motor~ In the ca~e of a hl~h-torque screw tlghtening operation, therefore, the r~action to the worker is 80 high as to cauqe fatigue to hi~ hands and shoulders. Further~ in order to effect hi~h-torque ti~htenin~ by using an electrically powered screw driver, it has be~n neces~ary to dra~tically reduce the r.p.m.
the bit 80 as to increase the motor torque, resulting in a poor efficiency of operation. ~hua, electrically powered tightening tools, which have the merit that the .~.power source which is available even in homes can be used, are confronted wibh various problem~, a3 described above.
Further, in conve~tional pneumatic screw drivers having a torque cut-off mechanism adapted to be actuated by a predetermined torque, the diffiulty of fine operation of the shut-off valve causes the air motor to be re-started at the ti~e o~ the resetting operation subsequent to tightening. Also in such drivers, a variation in the air ;~
pressure increases or decreases the torque of the air motor, thus influencing the tlghtenin6 torque. In a further arrangement having an exhaust ho~e installed therein, there is ye~ much noise and vibration produced during the tightening operation, which has come to be limelighted a~
an important problem in the present day when improvements in the assembling emvironment are clamored for.
In order to ellmina~e ths drawbacks`inherent ln the prior art a~ de~cribed above, the present invention has for its ob~ect the provision of an electrioally powered ' .: . , . : . :. . .. :, .. ~, , : .... ... . ... .. . .. . .
~OB7885 torque-controlled tool desig~ed to stop the ~lectric motor b~ the actio~ of a torque cut-off mechanism adapted to be po~itively moved when the screw-tightsning torque reache~
a fixed value, thereby greatly reducing the noise and vibration which have been con~idered to be the fatal draw-back~ to conventional pneumatic screw driver~, avoiding the reaction produced by the inertia moment ef the motor ~
armature.immediately after the tightening operationS and :
maintaining the r.p.m. of t~e bit at a constant value even /0 in a high-torque tightening operation, thereby making it possible to achieve a high efficiency of screw tightening operation.
It is al~o an ob~ect of the inventian to provide an electrically powered torque-controlled bool which achieves a high precision ti~htening torque by the use Or a clutch adapted to be acted upon by the aforesaid torque cut-off mechanism and which is capable of fully meeting the recent increasi~g demand for torqus control. `~ `
It is a further ob~ect of the invention to provide an electrically powered torque-oontrolled tool which is adapted to stop the electric motor immediately after fixed-torque tightening, a3 described above, 80 that the tool i~
pre~ented from causing occupational disea~e~, such as tenosynovitis, which has been recently at issue, and wherein the electric motor may be rotated only when neces-sary, thu~ reducing the noise and, more than anything else, making it po~sible to prolong the life of the electric ``
motor~ especially the brushes. ~`
: 4 -~:
~ 8 5 In order to achieve the above ob~ect~, the invention provide~ an electrically powered ~orque-controlled tool comprising an electric motor serving as a drive source, a switch for starting and stopping said electric motor, a clutch installed between ~aid electric motor and a bit so a~ to permit interruption and conti~u-ation of the transmi_sion of rotation between the both, a torque cut-off mechani~m adapted to act on said clutch when the torque by the bit reache~ a preset torque to :
thereby cut of~ the driving ~orce from the electric motor to the bit, a lock mechanism for holding ~aid clutch in its disengaged ~tate at the cut-off time, and a switch operating mechanism adapted to tranQmit the action of Raid torque eut-off mechanism to _aid ~witch.
~ he_e and other obJects and merits of the present invention will be readily u~der~tood from the following description o~ preferred embodiments of the invention~ which will be given with reference to the accompanying drawing~, in whieh:
Fig.1 i~ a longitudinal ~ection of an electrieall~
powered torque-controlled driver aceording to an embodiment of the invention;
~ ig.2a i9 a ~ectional view showing a elutch unit and a limit Qwitoh included in ~aid electrieally po~ered torque-controoled driver;
Fig.2b is a sectional ~iew taken along the line A-A of ~ig.2a;
~ ig.2c is a ~ectional view taken along the line B-B of ~ig.2a;
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Figs.3a, 3b and 3c are sectional views of principal portions ~ihowing the operatlng state of the clutch unit and limit switch;
Fig.4a i~ a sectional view showing another embodiment of clutch unit and a limit switch; and Fig.4b is a sectional view taken alon~ the line A-A of Fig.4a.
:~ First, referri~g to Fig.1, which i8 an entire view, the character a designates a power ~ou~ce unit;
/0 b designates a driving unit; c designates a speed-reducing unit; and d designates a clutch unitO
In the power source unit a, the numeral 1 desig- ~
nates a driver cord~ having an ac power ~ource receptable ?;
cap (not ~hown) fixed to the front end thereo~. The nume~al 2 de~ignates a switch u~ed for turning on and o~f the power and al~o for ~witching between forward and reverse rotations; and ~ designates hangers fixed to a top cover 4.
The numeral 6 designates a print board on which circuit parts which are the heart of the power source unit a are 0 placed, with a limi~ switch 7 fixed thereto. ~he numeral ~ desiignates a stepped pin for actuating the limit switch;
and 9 designates a spri~g in3talled between a ring 10 fitted on the stepped pin 9 and a partition plat~ 11, said spring 9 abutbing the flange portion 8a o~ the ~tepped pin 8 again~t the partition plate 11, while the lever 7a of the limit switch 7 abutting against the head o~ the flange portion ~a o~ the stepped pin 8. ~he numeral 12 deisignates screwa for ~ixing a split aheathing ca~e 14 ~or clamping ~:~
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:1~87B85 the top cover ~ and ~ront end cover 13 and co~erin~ the entire tool. ~he case 14 has its outer sur~ce shape formed with two ~ymmetrical curved surrace3 and has a 910p~ gradually thickening from the electric motor covering portion to the front end. ~he character 14a designates a rib o~ the ca~e 14 for fixing the partition plate 1~ in po~ition; 15 designates a bracket ~ecured to the partition plate 11 and to the l1mit switeh soldered to the pri~t board 6; and ~6 designate~ a ring for /o preventing the slipping-off of the protector bushing 1a of the driver cord 10 In the driving unit b, the numeral 17 designate~
a motor sha~t supported i~ ball bearlngs 21 ~nd 22 which are respectively ~itted in a bracket 19 fitted to a motor case 18 and another bracket 20 Or an electrioall~ non-; conductive material. A ran 24 is fixed through a fan boss 23 by a screw 25 to the portion of the motor shaft pro~ecting toward tha power source unit a, while a first sun gear 26 is adhesively fixed to the e~d of said motor o sha~t projectin~ toward the ~peed-reducing unit c. ~he motor shaft 17 is tubula~r, having a through-hole at the center, and received in said through-hole is a ~witch rod 27 whose head abuts against the end surface of the afore-said stepped pi~ 8 and which extends to the clut~h unit d.
The charaoters 28 and 28' designate nut~ for holding down electricall~ conductlve rings 29 and 29';
and 30 and 30' designate lead wires extending from the switch 2 to the motor and connected to the electricall~
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1~8781~
conductive rings 29 and 29'. Deqignata~ at 31 and 31' are lead wire guide pins pro~ecti~g from the ca~e 14.
~ he character 14b desi~nate~ holes proYided in the ca~e 14 for dissipating the ~enerated heat of the driving unit b by the fan 24, it being ~oted that th~
partition plate 11 serveq to ~hut off the hot air bei~g driven out by the fan ~4 that it may not influence the power source u~it a.
In the speed-reducing unit c, bhe character 32 J~ desig~ate~ fir~t plan~t gear~ of an electri~cally ~on-conductive material meshin~ with the first ~un gear 26 and an internal gear 33? I said planet gears rotating around the ;~ axes of the~r re~pective pins 35 press-~itted into a fir~t ~peed-reduction shart 34, saîd planet ~ears al~o revol~ing around the rir8t ~un gear 26, thereb~ executing a planetary motion. ~he numeral 36 designate~ a spacer of an elect~ically non-conductive material inserted betwee~ the bracket 20 and internal gear 33; and 37 designate6 a spacer of an electrically non-conductive ; ~ ~7~ material inserted between the fir~t planet ~ears 32 and first speed-reduction~sha~t.~ ~he numeral 38 designates econd pla~et Bear~ meshin~ with s seoond ~un ~ear 39 pr6ss-~itted on the first speed-reduction ~hafb 34 and ~.
with the internal ~ear 33 and rotating ~round the axe~
of respeoti~e pins 41 pre~qs-fitted into a second speed-redu¢tion shaft 40. ~ha numeral 42 designates a ball : ~
bearing fitted ini the internal ~ear 33 a~d retained b~ ~ -; a rin6 43, said ~econd speed-reduct~o~ shaft 40 being :`-~ .
~ 8 : . . .. - .,- . ~ , . . . , . .. -.:. .. ,. . .. ~ . . -78~5i ~itted in the inner race of said ball bearing 42. The int~.rnal gear 33 i8 fitted in the bracket 20 80 a~ ~ot to be circumferentially rotated.
In Fi~. 1 and 2 showing the clutch unit d, the numeral 44 designate~ a clutch ~haft, which is fitted i~
the second ~peed-reduction 3haft 40 and arranged 80 that the driving force may be ~ran~mltted by the front end flat portion of the clutch ~haft 44. ~he numeral 45 designates a lock spring interposed between a lock cam /0 46 and the clutch shaft 44; 4? designates a 4it holder fitted i~ the clutch shaft 44 and holding a bit 48 by means of a ball 49 and an ela~tic band 50; and 51 de~ignates a hammer ri~g which is axially slidabl~ and rotatably fitted on the clutch shaft 44 through a number of ball~ 52 and has square teeth 51a at one end thereof, said teeth 51a being adapted to engage ~quare teeth 54a o~ one end o.~ a clutch claw receiver 54 which is fitted on the bit holder 47 90 as to be slidable axially thereof but prevented b~ ball~ 53 from being ro~abed relative thereto. A retur~ spring 55 is interposed betwee~
the bit holder 47 and the clutch shaft 44, wbile a re~et spring 57 is i~terpo~ed between the clutch claw receiver 54 and a ring .56 ~itted on the bit holder 47.
A clutch ca~e 58 fitted on the internal ~ear 33 and screwed into the bracket 20 has coaxially screwed thereinto a cap 60 which has a bushing 59 press-fitted therei~to, with pins 61 slidably inserted in said cap 60.
One of the respective ends of the pins 61 abuts again~t ~1 :
:.
~7151~i a ring 62 and the other ends again~t an adju~ting nut 63.
A torque spring 64 i~ interposed betwee~ tha hammer ring 51 and the ring 62 through the intermediar~ of a spring seat 65 and balls 67 retained by a ball retaininK plate 66. The numeral 68 designates lock balls disposed between the lock cam 46 and the clutch claw receiver 54; 69 de~ignates a stop ball for the lock cam; and 70 designates a hnlder ring for the stop ball 69. ~he numeral 71 designates balls interposed between the clutch shaft 44 ;:
/0 and grooves 51bin the hammer rin~ 51 and abuttlng ..
against a ring 72 fitted o~ the clutch shA~t 44. ~he numeral 73 de~i~nates a retainer for a number of balls 52 interposed between the clutch shaft 44 a~d the hammer ring 51.
~ he relation betwen the clutch shaft 44, ball~ 71 and hammer ring 51 is as shown in Fig. 2b and is such that ~hen the clutch sha~t 44 and the hammer ring execute ~:
a relative rotary tion the ridBes 44a of the clutch s~haft 44 radiall~ ~outwar.dl~ push the ball~ 71 which, in ::
turn, depre~us the hammer ri~n~ 51 i~ the direction of ~;~
arrow a. ~he ~umeral 74 designates a ring fitted on the blt holder 47 and adap~ed to abut again~t the end surface of the bushing 59 at the time of stoppage. ~he numeral 75 de~ignates a ring fitted on the clutch shaft 44; 76 designates scr0ws whereby the sheathing case 14 and the front end cover 13 are put together; and 77. designates nuts therefor, ~-:
In the above arrangement, the operation will ~;
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~ 0 ~ ~ 8 ~5 now be described.
In Fi~.1, the A.C.current supplied through the driver cord 1 is passed through the limit switch 7 and then recti~ied b~ the circuit on the print board lnside the power source unit a, whereupon it is pas~ed through the switch 2 and then through the lead wires 30 and ~0' to be supplied to the dri~ing unit b. Thereupo~, the electric motor starts rotating to transmit the torque to the speed-reduction unit c~ Concurrently therewithg / 0 the fa~ 24 i8 rotated to draw the open air along a path indicated by arrows v1~ ~2 and V3, said air then flowin~
along a path indicated by arrows V4 and ~5 inside th~
motor to force the bot air into the atmosphere.
As the first sun gear 26 starts rotating, the first plane-t gears 32 rotatably attached to the first peed-reduction shaft ~4 by the pins 35 execute a planetary motion around the first sun gear 26 while meshing with the teeth of the internal gear 33, 50 that the rotation Or the first speed-reduction sha~t 34 is O what results from the rotation o~ the motor shaft 17 bein~
reduc~d in speed. ~urther, the second planet gear~ 38 rotatably attached to the second speed-reduction shaft 40 b~ the pins 41 execute a pla~etary motio~ around bhe second sun ~ear 39, which 1~ press-fitted on the ~i~st speed~
reduction shaft 34 and is coaxial with the fir~t speed-reduction shaft ~4, while meshing with the teeth of the i~ter~al gear 33, so thab the rotation of the second speed-reduction sha~t 40 is what results from the ~-~
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~ 5 rotation of the fir~t speed-reductio~ shaft ~4 being reduced in speed. As a result, the rotation of the motor ~ha~t 17 is reduced in speed twice and taken out by the second speed-reduction shaft ~0. ;:
In this connection, it is to ba noted that i~
order to i801ate the speed-reducing section ~rom the driving u~it b, the internal gear 33 is ooaxially fitted in the bracket 20 of an electrically no~-conductive material, that the ~irst planet gears ~2 revolvin~ around /~ the fir3t sun gear 26 adhesivel~ fixed to the motor shart 17 i~ al~o made of an electrically non-conducti~e materiall `
and that the spacer 37 of an electrically non-conductive material is interposed between the end surface of the first ~un gear 26 and the first speed-reduction shart 34 Further, the switch rod 27 is al80 made of an electricall~ -non-conductive material, whereby the speed-reductio~ unit c and the clutch unit d are isolated.
: ~he fir~t speed-reduction unit constituted by the fir~t planet gears 32, pins 35, spaoer 37, fir~t spe.ed-~2~ reductio~ shart 34 and~second su~ gear 39 has the ~pacer ..
36 i~terposed between it~elf and the bracket 20 to reduce sliaing friction produoed b~ the relati~e spqed and cause ~aid first speed-reduction unit to f~oat. Further, profile shirting i~ applied to the firsb planet gears 32, first eun ~ear ?6 a~d internal gear ~3 and to the seco~d ~un gear 39 and second planet gears 38 80 a~ to assure the proper meshing of their teeth or the backlash :
ha~ been adjusted so as to have an optimum value.
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~0~781~;
Therefore, the first ~peed-reduction unit will ~moothly execute a rotary motlon while playi~g a self-ali~ning role.
~ he motor shaft 17 $9 reduced i~ speed in two stage~, and the torque of the driving unit b i~ tra~smitted from the second speed-reductio~ shaft 40 to the clutch unit d. However, in a state where the bit 48 i~ not yet pressed a~ before it drive~ a screw9 as shown in ~ig. 2a, the limit switch 7 is not in a position to allow electric ~Q current to pass..therethrough, 90 that the motor does ~ot rotate. When the bit 48 i8 pressed in the direction of arrow b in order to drive a screw, as ~hown in ~ig. 3a, th~ bit holder 47 i8 backwardly moved against the force of the return ~pring 55, causing the lock ball 68 to abut against the slope 46a of the lock cam 46 to 4ackwardl~
move the latter again~t the force of the lock sprin~ 45, depressing the switch rod 27 to backwardly move the ~tepped pin 8 a6ainst the ~orce of the sprin~ 9, thereby aotuating the limit switoh 7. As a result, the electric ~ motor ~ar~s rota~in~, 50 that a torque which i5 decelerated~and strengthened by the action o~ the speed-reducing unit o:is tran~mitted to the clutch shaft 44 a~d the ha~mer ring 51 ~tarts rotatinæ through the inter-med~ar~ o~ the ball3 710 Co~currentl~ therewith, und~r the action Or the resilient ~orce of the reseb spring 57 the teeth 54a of the clutch claw receiver 54 backwardly moving iutegrally wi:th the bit holder 47 engage the teeth 51a of said hammer rin6 51, thus ~tarting to rotate the : . - 13 -. .:.. : ~,.. ~ . . ..
bit holder 47 through the intermediary of the clutch claw receiver 54 and balls 53, 90 that the ~crew (not shown) which i8 enKaged with the bi~ 48 start8 to b~ screwed.
~he movement of the bit holder 47 in the dir~ction of arrow b i8 stopped when it~ rear step surface abut~
against the front e~d surface of the clutch shaft 44, but the construction i8 such that the thrust load acti~g in the direction of arrow b is applied to the inner race of : the ball bearing 42 by the clutch ~haft 44 90 that it ~a does not influence the sècond speed-reducbion shaft 40 at all. :
When the screw haq been tighte~ed up, as shown ~ :
in Fig. 3b, the ridges 44a of the clutch shaft 44 radiall~
outwardl~ push the balls 71, depressing bhe haimmer ring .
51 in the dire¢tio~ of arrow a against the force o~ the tor~ue spring 64. Concurrently therewith, the clutch claw recei~er 54 is al80 moved against the force of the reset spring S7 until the hollow portion ~b of the clutch claw receiver 54 is positioned above the lock o2~ balls 68. W~th thi~ state established, the lock cam 46 urged b~ the lock spring 45 pushes up the lock balls 68 by lts slope 46 to fit ~hem into said hollow portion 54b.
800n a~ this ball fittin~ takes place, the switGh spring 9 pu8he8 back the switch rod 27, as shown in Flg. 3c, thereb~ cutting of~ the current flowing to the .
motor.
Concurrently therewith, the hammer ring 51, under the action o~ the torque sprin~ 64, drops the b~lls 71 : - 14 -~
. . : . .,: : , : . . . ;: -. .: . ~ . - .,: : . . :; :: ~ .
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78~9~
onto the flats 44b of the clutch sha~t 44 and return~ to its ori~inal po~ition. Therefora, the taeth 5~a a~d 54b are dise~ga~ed from each okher, 80 that the driving force is completely cut orf. As a result, there i8 no reaction to the worker' 9 hands due to ~he inertia moment of the motor armature (not shown) when the motor is qtopped, i.e., whe~ the screw has been ti~htened up, and very little noîse is produced.
When the bit is pushed back from the state o~
~; /0 Fig~ 3c in ~he direction of arrow d by bhe resilient force of the return spring 55, the lock balls 68 are positioned above the vall~y 46b of the lock cam 46, and with thi~ state e~tablished, the lock ball~ 68 can be ea~ily dropped thereinto by the resilient force of the reset spring 57, 80 that the state prior to screwin~
i.e., the state of Fig. 2a is restored.
~ he balls 67 serve to reduce the friction produced by the relative movement of the hammer ring 51 and torque spring 64~ The adjustment of the ti~htening c20 torgue can be made by tighteni~g the adjusting nut 63, causing the~pin~ 61 to move the ring 62 to compress the to:rque spring 64, thereby increasing the re~silient force.
In Figs. 4a and 4b showing another embodiment o~
thR clutch unit c, the numeral 78 designates a ¢lutch shaft fitted ln a second ~peed-reducbion shafb 40 and ~, adapted to transmit the driving force by its front end flat portio~.~ The nu~eral 79 designates a ri~g for transmittin~ the thru~t on the clutch shaft 78 to the : ~
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~78~S
inner rac~ of a ball bearing 42. The numeral 80 de~ignates a lock ~pring interpo~ed betwaen a lock cam 81 a~d the clutch shaft 78; 82 de~ignates a bit holder fitted on the clutch shaft 78 and ~exving to hold a bit by means of ~ ball 84 and an elastic band 85; 86 desiKnates a bal}
holder rotatably fitted on the clutch sha~t 78 through ~--balla 87 and 88 ~or retaining ball~ 89; and 90 de~ignates a hammer ring which is fitted on the ball holder 86 so that it is slidable but not rotatable relative thereto, 0 and wh~ch ha~ ~quare teeth 90a on one end thereof. The teeth 90a are adapted to engage square teeth 92a o~ one end of a olutch claw receiver 92 which i8 fitted on the bit holder 82 so as to be slidable axially thereof but prevented b~ balls 91 fxom being rotated relative thereboO
A return spring 94 is interposed between the bit holder 82 and the ball holder 86 through the intermediary of balls 88 and a ring 9~, while a reset spring 96 is intexposed between the clutch claw receiver 92 and a ring ` :
.". 95 ritted on the bit holder 82. ~ :
~ he relatio~ between ;the clutch shaft 78, the ball~ 89 and the.ball holder 86 is a~ shown in Fig. 4b and is ~uch that wh~n the clutch shaft 78 and the ball holder 86 execute a relative rot~ry motion, the rid~e~
78a of bhe clutch sha~t 78 radially outwardly push out the balls 89 which, in turn, ~epres~ the hammer ri~g 90 in the direction of arrow a.
The numeral 110 de~ignates a lever for actuatlng ~:~
a limit switch 111; 112 designate~ a pin serving as an _ 16 -.,, ~
:
~17885 axi~ around which the lever 111 i8 -turned; and 113 de~ignates a ~prin~ for urgin~ the lever toward the limit switch 111.
The function of the clutch u~it hown in Figs.
4a and 4b differs from that of the clutch unit in the first embodiment shown in Figq. 1 throu~h 3 in that when the bit holder attains a preset torque, the clutch shaft 78 and ball holder 86 execute a relati~e rotary motion and the hammer ring 90 rotation-wise coupled with the J~ ball holder 86 is rotated integrall~ with the ball holder 86 and at the ~ame time i5 moved axially of the ball holder 86~ and that th~ direction of actuation of the limit switch 111 i9 rever~ed. The re~t Or the function i9 the same.
~ n the abo~e arrangement, since the power source unit a, driving unit b, speed-reducing unit c and clutch unit d are prepared as indi~idual units, it i~
pos~ible to perform 6crew tightening operation~ efficient-ly and properly by preparing several kinds of each unit and changing the combination of units a-d accordi~g to the type of the screw bo be tightened and the tightening torque~ Further, i~ this electrically powered torque-controlled tool i~ used with an automatic screw ~eeding apparatu~, the eff`ici~ncy will be much higher.
As has b~en described ~o far, the electrically powered torque-controlled tool açcording to the embodiments is designed so that the motor i~ rotated by the pres~ing action of the tool exerted when the worker '~
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tightens th~ screw or nut, while the electric motor is stopped by the action Or the torque cut-off mechani~
adaptsd to be po~itively moved when the screw tightaning torque reaches a fixed vAlue, thereby greatly reducing the noi~e and vibration which have been considered to be the fatal drawback~ to conventional pneumatic dri~ers, avoiding the reaction which would otherwi~e be produced ~-by th~ inertia moment of the motor armature imme~iately after the tightening operation, ~nd maintaining ther.p.m.
/~ o~ the bit at a constant value even in a high-torque tightenin~ operation, thereby making it possible to achie~e a high ef~icienc~ of screw tightenin6 operation.
Further, the clutch adapted to be acted upon by the a~ore~aid torque cut-off mechanism achie~es a high-precision tightsning torque and fully meet~ the recent increasing demand for torque control.
~ urther, since the electrically powered torque controlled tool of the embodiments is de~iBned to push-3tart the electric motor and ~top it immediately after flxed torque tight~enlng, as described above,~the tool 1s prèvented f`rom cau~ing occupational disea~es, ~uch as tenosyncvitis, which has bee~n recentl~ at i~sue; and since the ele~tric~ motor ma~ be rotated only when necessary, the noise i~ reduced and, more than anythi~g else~ the life Or the 01ectric motor, especially the brushe~ ca~ be prolonged.
, ~ - 18 -:~, ,
' ~L~878B5 the ~toppage of the motor~ In the ca~e of a hl~h-torque screw tlghtening operation, therefore, the r~action to the worker is 80 high as to cauqe fatigue to hi~ hands and shoulders. Further~ in order to effect hi~h-torque ti~htenin~ by using an electrically powered screw driver, it has be~n neces~ary to dra~tically reduce the r.p.m.
the bit 80 as to increase the motor torque, resulting in a poor efficiency of operation. ~hua, electrically powered tightening tools, which have the merit that the .~.power source which is available even in homes can be used, are confronted wibh various problem~, a3 described above.
Further, in conve~tional pneumatic screw drivers having a torque cut-off mechanism adapted to be actuated by a predetermined torque, the diffiulty of fine operation of the shut-off valve causes the air motor to be re-started at the ti~e o~ the resetting operation subsequent to tightening. Also in such drivers, a variation in the air ;~
pressure increases or decreases the torque of the air motor, thus influencing the tlghtenin6 torque. In a further arrangement having an exhaust ho~e installed therein, there is ye~ much noise and vibration produced during the tightening operation, which has come to be limelighted a~
an important problem in the present day when improvements in the assembling emvironment are clamored for.
In order to ellmina~e ths drawbacks`inherent ln the prior art a~ de~cribed above, the present invention has for its ob~ect the provision of an electrioally powered ' .: . , . : . :. . .. :, .. ~, , : .... ... . ... .. . .. . .
~OB7885 torque-controlled tool desig~ed to stop the ~lectric motor b~ the actio~ of a torque cut-off mechanism adapted to be po~itively moved when the screw-tightsning torque reache~
a fixed value, thereby greatly reducing the noise and vibration which have been con~idered to be the fatal draw-back~ to conventional pneumatic screw driver~, avoiding the reaction produced by the inertia moment ef the motor ~
armature.immediately after the tightening operationS and :
maintaining the r.p.m. of t~e bit at a constant value even /0 in a high-torque tightening operation, thereby making it possible to achieve a high efficiency of screw tightening operation.
It is al~o an ob~ect of the inventian to provide an electrically powered torque-controlled bool which achieves a high precision ti~htening torque by the use Or a clutch adapted to be acted upon by the aforesaid torque cut-off mechanism and which is capable of fully meeting the recent increasi~g demand for torqus control. `~ `
It is a further ob~ect of the invention to provide an electrically powered torque-oontrolled tool which is adapted to stop the electric motor immediately after fixed-torque tightening, a3 described above, 80 that the tool i~
pre~ented from causing occupational disea~e~, such as tenosynovitis, which has been recently at issue, and wherein the electric motor may be rotated only when neces-sary, thu~ reducing the noise and, more than anything else, making it po~sible to prolong the life of the electric ``
motor~ especially the brushes. ~`
: 4 -~:
~ 8 5 In order to achieve the above ob~ect~, the invention provide~ an electrically powered ~orque-controlled tool comprising an electric motor serving as a drive source, a switch for starting and stopping said electric motor, a clutch installed between ~aid electric motor and a bit so a~ to permit interruption and conti~u-ation of the transmi_sion of rotation between the both, a torque cut-off mechani~m adapted to act on said clutch when the torque by the bit reache~ a preset torque to :
thereby cut of~ the driving ~orce from the electric motor to the bit, a lock mechanism for holding ~aid clutch in its disengaged ~tate at the cut-off time, and a switch operating mechanism adapted to tranQmit the action of Raid torque eut-off mechanism to _aid ~witch.
~ he_e and other obJects and merits of the present invention will be readily u~der~tood from the following description o~ preferred embodiments of the invention~ which will be given with reference to the accompanying drawing~, in whieh:
Fig.1 i~ a longitudinal ~ection of an electrieall~
powered torque-controlled driver aceording to an embodiment of the invention;
~ ig.2a i9 a ~ectional view showing a elutch unit and a limit Qwitoh included in ~aid electrieally po~ered torque-controoled driver;
Fig.2b is a sectional ~iew taken along the line A-A of ~ig.2a;
~ ig.2c is a ~ectional view taken along the line B-B of ~ig.2a;
~ - 5 -~87~3~S
Figs.3a, 3b and 3c are sectional views of principal portions ~ihowing the operatlng state of the clutch unit and limit switch;
Fig.4a i~ a sectional view showing another embodiment of clutch unit and a limit switch; and Fig.4b is a sectional view taken alon~ the line A-A of Fig.4a.
:~ First, referri~g to Fig.1, which i8 an entire view, the character a designates a power ~ou~ce unit;
/0 b designates a driving unit; c designates a speed-reducing unit; and d designates a clutch unitO
In the power source unit a, the numeral 1 desig- ~
nates a driver cord~ having an ac power ~ource receptable ?;
cap (not ~hown) fixed to the front end thereo~. The nume~al 2 de~ignates a switch u~ed for turning on and o~f the power and al~o for ~witching between forward and reverse rotations; and ~ designates hangers fixed to a top cover 4.
The numeral 6 designates a print board on which circuit parts which are the heart of the power source unit a are 0 placed, with a limi~ switch 7 fixed thereto. ~he numeral ~ desiignates a stepped pin for actuating the limit switch;
and 9 designates a spri~g in3talled between a ring 10 fitted on the stepped pin 9 and a partition plat~ 11, said spring 9 abutbing the flange portion 8a o~ the ~tepped pin 8 again~t the partition plate 11, while the lever 7a of the limit switch 7 abutting against the head o~ the flange portion ~a o~ the stepped pin 8. ~he numeral 12 deisignates screwa for ~ixing a split aheathing ca~e 14 ~or clamping ~:~
`.: '.
- 6 - ~ ~
,' ' ':
:1~87B85 the top cover ~ and ~ront end cover 13 and co~erin~ the entire tool. ~he case 14 has its outer sur~ce shape formed with two ~ymmetrical curved surrace3 and has a 910p~ gradually thickening from the electric motor covering portion to the front end. ~he character 14a designates a rib o~ the ca~e 14 for fixing the partition plate 1~ in po~ition; 15 designates a bracket ~ecured to the partition plate 11 and to the l1mit switeh soldered to the pri~t board 6; and ~6 designate~ a ring for /o preventing the slipping-off of the protector bushing 1a of the driver cord 10 In the driving unit b, the numeral 17 designate~
a motor sha~t supported i~ ball bearlngs 21 ~nd 22 which are respectively ~itted in a bracket 19 fitted to a motor case 18 and another bracket 20 Or an electrioall~ non-; conductive material. A ran 24 is fixed through a fan boss 23 by a screw 25 to the portion of the motor shaft pro~ecting toward tha power source unit a, while a first sun gear 26 is adhesively fixed to the e~d of said motor o sha~t projectin~ toward the ~peed-reducing unit c. ~he motor shaft 17 is tubula~r, having a through-hole at the center, and received in said through-hole is a ~witch rod 27 whose head abuts against the end surface of the afore-said stepped pi~ 8 and which extends to the clut~h unit d.
The charaoters 28 and 28' designate nut~ for holding down electricall~ conductlve rings 29 and 29';
and 30 and 30' designate lead wires extending from the switch 2 to the motor and connected to the electricall~
.: :
1~8781~
conductive rings 29 and 29'. Deqignata~ at 31 and 31' are lead wire guide pins pro~ecti~g from the ca~e 14.
~ he character 14b desi~nate~ holes proYided in the ca~e 14 for dissipating the ~enerated heat of the driving unit b by the fan 24, it being ~oted that th~
partition plate 11 serveq to ~hut off the hot air bei~g driven out by the fan ~4 that it may not influence the power source u~it a.
In the speed-reducing unit c, bhe character 32 J~ desig~ate~ fir~t plan~t gear~ of an electri~cally ~on-conductive material meshin~ with the first ~un gear 26 and an internal gear 33? I said planet gears rotating around the ;~ axes of the~r re~pective pins 35 press-~itted into a fir~t ~peed-reduction shart 34, saîd planet ~ears al~o revol~ing around the rir8t ~un gear 26, thereb~ executing a planetary motion. ~he numeral 36 designate~ a spacer of an elect~ically non-conductive material inserted betwee~ the bracket 20 and internal gear 33; and 37 designate6 a spacer of an electrically non-conductive ; ~ ~7~ material inserted between the fir~t planet ~ears 32 and first speed-reduction~sha~t.~ ~he numeral 38 designates econd pla~et Bear~ meshin~ with s seoond ~un ~ear 39 pr6ss-~itted on the first speed-reduction ~hafb 34 and ~.
with the internal ~ear 33 and rotating ~round the axe~
of respeoti~e pins 41 pre~qs-fitted into a second speed-redu¢tion shaft 40. ~ha numeral 42 designates a ball : ~
bearing fitted ini the internal ~ear 33 a~d retained b~ ~ -; a rin6 43, said ~econd speed-reduct~o~ shaft 40 being :`-~ .
~ 8 : . . .. - .,- . ~ , . . . , . .. -.:. .. ,. . .. ~ . . -78~5i ~itted in the inner race of said ball bearing 42. The int~.rnal gear 33 i8 fitted in the bracket 20 80 a~ ~ot to be circumferentially rotated.
In Fi~. 1 and 2 showing the clutch unit d, the numeral 44 designate~ a clutch ~haft, which is fitted i~
the second ~peed-reduction 3haft 40 and arranged 80 that the driving force may be ~ran~mltted by the front end flat portion of the clutch ~haft 44. ~he numeral 45 designates a lock spring interposed between a lock cam /0 46 and the clutch shaft 44; 4? designates a 4it holder fitted i~ the clutch shaft 44 and holding a bit 48 by means of a ball 49 and an ela~tic band 50; and 51 de~ignates a hammer ri~g which is axially slidabl~ and rotatably fitted on the clutch shaft 44 through a number of ball~ 52 and has square teeth 51a at one end thereof, said teeth 51a being adapted to engage ~quare teeth 54a o~ one end o.~ a clutch claw receiver 54 which is fitted on the bit holder 47 90 as to be slidable axially thereof but prevented b~ ball~ 53 from being ro~abed relative thereto. A retur~ spring 55 is interposed betwee~
the bit holder 47 and the clutch shaft 44, wbile a re~et spring 57 is i~terpo~ed between the clutch claw receiver 54 and a ring .56 ~itted on the bit holder 47.
A clutch ca~e 58 fitted on the internal ~ear 33 and screwed into the bracket 20 has coaxially screwed thereinto a cap 60 which has a bushing 59 press-fitted therei~to, with pins 61 slidably inserted in said cap 60.
One of the respective ends of the pins 61 abuts again~t ~1 :
:.
~7151~i a ring 62 and the other ends again~t an adju~ting nut 63.
A torque spring 64 i~ interposed betwee~ tha hammer ring 51 and the ring 62 through the intermediar~ of a spring seat 65 and balls 67 retained by a ball retaininK plate 66. The numeral 68 designates lock balls disposed between the lock cam 46 and the clutch claw receiver 54; 69 de~ignates a stop ball for the lock cam; and 70 designates a hnlder ring for the stop ball 69. ~he numeral 71 designates balls interposed between the clutch shaft 44 ;:
/0 and grooves 51bin the hammer rin~ 51 and abuttlng ..
against a ring 72 fitted o~ the clutch shA~t 44. ~he numeral 73 de~i~nates a retainer for a number of balls 52 interposed between the clutch shaft 44 a~d the hammer ring 51.
~ he relation betwen the clutch shaft 44, ball~ 71 and hammer ring 51 is as shown in Fig. 2b and is such that ~hen the clutch sha~t 44 and the hammer ring execute ~:
a relative rotary tion the ridBes 44a of the clutch s~haft 44 radiall~ ~outwar.dl~ push the ball~ 71 which, in ::
turn, depre~us the hammer ri~n~ 51 i~ the direction of ~;~
arrow a. ~he ~umeral 74 designates a ring fitted on the blt holder 47 and adap~ed to abut again~t the end surface of the bushing 59 at the time of stoppage. ~he numeral 75 de~ignates a ring fitted on the clutch shaft 44; 76 designates scr0ws whereby the sheathing case 14 and the front end cover 13 are put together; and 77. designates nuts therefor, ~-:
In the above arrangement, the operation will ~;
- 10 - ~
:
;~ ...
~ 0 ~ ~ 8 ~5 now be described.
In Fi~.1, the A.C.current supplied through the driver cord 1 is passed through the limit switch 7 and then recti~ied b~ the circuit on the print board lnside the power source unit a, whereupon it is pas~ed through the switch 2 and then through the lead wires 30 and ~0' to be supplied to the dri~ing unit b. Thereupo~, the electric motor starts rotating to transmit the torque to the speed-reduction unit c~ Concurrently therewithg / 0 the fa~ 24 i8 rotated to draw the open air along a path indicated by arrows v1~ ~2 and V3, said air then flowin~
along a path indicated by arrows V4 and ~5 inside th~
motor to force the bot air into the atmosphere.
As the first sun gear 26 starts rotating, the first plane-t gears 32 rotatably attached to the first peed-reduction shaft ~4 by the pins 35 execute a planetary motion around the first sun gear 26 while meshing with the teeth of the internal gear 33, 50 that the rotation Or the first speed-reduction sha~t 34 is O what results from the rotation o~ the motor shaft 17 bein~
reduc~d in speed. ~urther, the second planet gear~ 38 rotatably attached to the second speed-reduction shaft 40 b~ the pins 41 execute a pla~etary motio~ around bhe second sun ~ear 39, which 1~ press-fitted on the ~i~st speed~
reduction shaft 34 and is coaxial with the fir~t speed-reduction shaft ~4, while meshing with the teeth of the i~ter~al gear 33, so thab the rotation of the second speed-reduction sha~t 40 is what results from the ~-~
- 11 - ' ~, : .. . . . . . .
~ 5 rotation of the fir~t speed-reductio~ shaft ~4 being reduced in speed. As a result, the rotation of the motor ~ha~t 17 is reduced in speed twice and taken out by the second speed-reduction shaft ~0. ;:
In this connection, it is to ba noted that i~
order to i801ate the speed-reducing section ~rom the driving u~it b, the internal gear 33 is ooaxially fitted in the bracket 20 of an electrically no~-conductive material, that the ~irst planet gears ~2 revolvin~ around /~ the fir3t sun gear 26 adhesivel~ fixed to the motor shart 17 i~ al~o made of an electrically non-conducti~e materiall `
and that the spacer 37 of an electrically non-conductive material is interposed between the end surface of the first ~un gear 26 and the first speed-reduction shart 34 Further, the switch rod 27 is al80 made of an electricall~ -non-conductive material, whereby the speed-reductio~ unit c and the clutch unit d are isolated.
: ~he fir~t speed-reduction unit constituted by the fir~t planet gears 32, pins 35, spaoer 37, fir~t spe.ed-~2~ reductio~ shart 34 and~second su~ gear 39 has the ~pacer ..
36 i~terposed between it~elf and the bracket 20 to reduce sliaing friction produoed b~ the relati~e spqed and cause ~aid first speed-reduction unit to f~oat. Further, profile shirting i~ applied to the firsb planet gears 32, first eun ~ear ?6 a~d internal gear ~3 and to the seco~d ~un gear 39 and second planet gears 38 80 a~ to assure the proper meshing of their teeth or the backlash :
ha~ been adjusted so as to have an optimum value.
- 12 - .
.
~0~781~;
Therefore, the first ~peed-reduction unit will ~moothly execute a rotary motlon while playi~g a self-ali~ning role.
~ he motor shaft 17 $9 reduced i~ speed in two stage~, and the torque of the driving unit b i~ tra~smitted from the second speed-reductio~ shaft 40 to the clutch unit d. However, in a state where the bit 48 i~ not yet pressed a~ before it drive~ a screw9 as shown in ~ig. 2a, the limit switch 7 is not in a position to allow electric ~Q current to pass..therethrough, 90 that the motor does ~ot rotate. When the bit 48 i8 pressed in the direction of arrow b in order to drive a screw, as ~hown in ~ig. 3a, th~ bit holder 47 i8 backwardly moved against the force of the return ~pring 55, causing the lock ball 68 to abut against the slope 46a of the lock cam 46 to 4ackwardl~
move the latter again~t the force of the lock sprin~ 45, depressing the switch rod 27 to backwardly move the ~tepped pin 8 a6ainst the ~orce of the sprin~ 9, thereby aotuating the limit switoh 7. As a result, the electric ~ motor ~ar~s rota~in~, 50 that a torque which i5 decelerated~and strengthened by the action o~ the speed-reducing unit o:is tran~mitted to the clutch shaft 44 a~d the ha~mer ring 51 ~tarts rotatinæ through the inter-med~ar~ o~ the ball3 710 Co~currentl~ therewith, und~r the action Or the resilient ~orce of the reseb spring 57 the teeth 54a of the clutch claw receiver 54 backwardly moving iutegrally wi:th the bit holder 47 engage the teeth 51a of said hammer rin6 51, thus ~tarting to rotate the : . - 13 -. .:.. : ~,.. ~ . . ..
bit holder 47 through the intermediary of the clutch claw receiver 54 and balls 53, 90 that the ~crew (not shown) which i8 enKaged with the bi~ 48 start8 to b~ screwed.
~he movement of the bit holder 47 in the dir~ction of arrow b i8 stopped when it~ rear step surface abut~
against the front e~d surface of the clutch shaft 44, but the construction i8 such that the thrust load acti~g in the direction of arrow b is applied to the inner race of : the ball bearing 42 by the clutch ~haft 44 90 that it ~a does not influence the sècond speed-reducbion shaft 40 at all. :
When the screw haq been tighte~ed up, as shown ~ :
in Fig. 3b, the ridges 44a of the clutch shaft 44 radiall~
outwardl~ push the balls 71, depressing bhe haimmer ring .
51 in the dire¢tio~ of arrow a against the force o~ the tor~ue spring 64. Concurrently therewith, the clutch claw recei~er 54 is al80 moved against the force of the reset spring S7 until the hollow portion ~b of the clutch claw receiver 54 is positioned above the lock o2~ balls 68. W~th thi~ state established, the lock cam 46 urged b~ the lock spring 45 pushes up the lock balls 68 by lts slope 46 to fit ~hem into said hollow portion 54b.
800n a~ this ball fittin~ takes place, the switGh spring 9 pu8he8 back the switch rod 27, as shown in Flg. 3c, thereb~ cutting of~ the current flowing to the .
motor.
Concurrently therewith, the hammer ring 51, under the action o~ the torque sprin~ 64, drops the b~lls 71 : - 14 -~
. . : . .,: : , : . . . ;: -. .: . ~ . - .,: : . . :; :: ~ .
, ~ . ~ . .
78~9~
onto the flats 44b of the clutch sha~t 44 and return~ to its ori~inal po~ition. Therefora, the taeth 5~a a~d 54b are dise~ga~ed from each okher, 80 that the driving force is completely cut orf. As a result, there i8 no reaction to the worker' 9 hands due to ~he inertia moment of the motor armature (not shown) when the motor is qtopped, i.e., whe~ the screw has been ti~htened up, and very little noîse is produced.
When the bit is pushed back from the state o~
~; /0 Fig~ 3c in ~he direction of arrow d by bhe resilient force of the return spring 55, the lock balls 68 are positioned above the vall~y 46b of the lock cam 46, and with thi~ state e~tablished, the lock ball~ 68 can be ea~ily dropped thereinto by the resilient force of the reset spring 57, 80 that the state prior to screwin~
i.e., the state of Fig. 2a is restored.
~ he balls 67 serve to reduce the friction produced by the relative movement of the hammer ring 51 and torque spring 64~ The adjustment of the ti~htening c20 torgue can be made by tighteni~g the adjusting nut 63, causing the~pin~ 61 to move the ring 62 to compress the to:rque spring 64, thereby increasing the re~silient force.
In Figs. 4a and 4b showing another embodiment o~
thR clutch unit c, the numeral 78 designates a ¢lutch shaft fitted ln a second ~peed-reducbion shafb 40 and ~, adapted to transmit the driving force by its front end flat portio~.~ The nu~eral 79 designates a ri~g for transmittin~ the thru~t on the clutch shaft 78 to the : ~
- 15 - ~
;~
~ .
~78~S
inner rac~ of a ball bearing 42. The numeral 80 de~ignates a lock ~pring interpo~ed betwaen a lock cam 81 a~d the clutch shaft 78; 82 de~ignates a bit holder fitted on the clutch shaft 78 and ~exving to hold a bit by means of ~ ball 84 and an elastic band 85; 86 desiKnates a bal}
holder rotatably fitted on the clutch sha~t 78 through ~--balla 87 and 88 ~or retaining ball~ 89; and 90 de~ignates a hammer ring which is fitted on the ball holder 86 so that it is slidable but not rotatable relative thereto, 0 and wh~ch ha~ ~quare teeth 90a on one end thereof. The teeth 90a are adapted to engage square teeth 92a o~ one end of a olutch claw receiver 92 which i8 fitted on the bit holder 82 so as to be slidable axially thereof but prevented b~ balls 91 fxom being rotated relative thereboO
A return spring 94 is interposed between the bit holder 82 and the ball holder 86 through the intermediary of balls 88 and a ring 9~, while a reset spring 96 is intexposed between the clutch claw receiver 92 and a ring ` :
.". 95 ritted on the bit holder 82. ~ :
~ he relatio~ between ;the clutch shaft 78, the ball~ 89 and the.ball holder 86 is a~ shown in Fig. 4b and is ~uch that wh~n the clutch shaft 78 and the ball holder 86 execute a relative rot~ry motion, the rid~e~
78a of bhe clutch sha~t 78 radially outwardly push out the balls 89 which, in turn, ~epres~ the hammer ri~g 90 in the direction of arrow a.
The numeral 110 de~ignates a lever for actuatlng ~:~
a limit switch 111; 112 designate~ a pin serving as an _ 16 -.,, ~
:
~17885 axi~ around which the lever 111 i8 -turned; and 113 de~ignates a ~prin~ for urgin~ the lever toward the limit switch 111.
The function of the clutch u~it hown in Figs.
4a and 4b differs from that of the clutch unit in the first embodiment shown in Figq. 1 throu~h 3 in that when the bit holder attains a preset torque, the clutch shaft 78 and ball holder 86 execute a relati~e rotary motion and the hammer ring 90 rotation-wise coupled with the J~ ball holder 86 is rotated integrall~ with the ball holder 86 and at the ~ame time i5 moved axially of the ball holder 86~ and that th~ direction of actuation of the limit switch 111 i9 rever~ed. The re~t Or the function i9 the same.
~ n the abo~e arrangement, since the power source unit a, driving unit b, speed-reducing unit c and clutch unit d are prepared as indi~idual units, it i~
pos~ible to perform 6crew tightening operation~ efficient-ly and properly by preparing several kinds of each unit and changing the combination of units a-d accordi~g to the type of the screw bo be tightened and the tightening torque~ Further, i~ this electrically powered torque-controlled tool i~ used with an automatic screw ~eeding apparatu~, the eff`ici~ncy will be much higher.
As has b~en described ~o far, the electrically powered torque-controlled tool açcording to the embodiments is designed so that the motor i~ rotated by the pres~ing action of the tool exerted when the worker '~
. ;
:, :
- 101!~781~S
tightens th~ screw or nut, while the electric motor is stopped by the action Or the torque cut-off mechani~
adaptsd to be po~itively moved when the screw tightaning torque reaches a fixed vAlue, thereby greatly reducing the noi~e and vibration which have been considered to be the fatal drawback~ to conventional pneumatic dri~ers, avoiding the reaction which would otherwi~e be produced ~-by th~ inertia moment of the motor armature imme~iately after the tightening operation, ~nd maintaining ther.p.m.
/~ o~ the bit at a constant value even in a high-torque tightenin~ operation, thereby making it possible to achie~e a high ef~icienc~ of screw tightenin6 operation.
Further, the clutch adapted to be acted upon by the a~ore~aid torque cut-off mechanism achie~es a high-precision tightsning torque and fully meet~ the recent increasing demand for torque control.
~ urther, since the electrically powered torque controlled tool of the embodiments is de~iBned to push-3tart the electric motor and ~top it immediately after flxed torque tight~enlng, as described above,~the tool 1s prèvented f`rom cau~ing occupational disea~es, ~uch as tenosyncvitis, which has bee~n recentl~ at i~sue; and since the ele~tric~ motor ma~ be rotated only when necessary, the noise i~ reduced and, more than anythi~g else~ the life Or the 01ectric motor, especially the brushe~ ca~ be prolonged.
, ~ - 18 -:~, ,
Claims (14)
1. An electrically powered torque-controlled tool comprising:
an electric motor which is a drive source;
a switch for starting and stopping said electric motor;
a clutch installed between said electric motor and a bit so as to permit interruption and continuation of the transmission of rotation between the both;
a torque cut-off mechanism adapted to act on said clutch when the torque by the bit reaches a preset torque to thereby cut off the driving force from the electric motor to the bit;
a lock mechanism for holding said clutch in its disengaged state at the cut-off time; and a switch operating mechanism adapted to transmit the action or said torque cut-off mechanism to said switch.
an electric motor which is a drive source;
a switch for starting and stopping said electric motor;
a clutch installed between said electric motor and a bit so as to permit interruption and continuation of the transmission of rotation between the both;
a torque cut-off mechanism adapted to act on said clutch when the torque by the bit reaches a preset torque to thereby cut off the driving force from the electric motor to the bit;
a lock mechanism for holding said clutch in its disengaged state at the cut-off time; and a switch operating mechanism adapted to transmit the action or said torque cut-off mechanism to said switch.
2. An electrically powered torque-controlled tool as set forth in claim 1, wherein said torque cut-off mechanism comprises a driving member which receives the torque from the electric motor, a driven member axially slidable on said driving member, and cam means interposed between said two members.
3. An electrically powered torque-controlled tool as set forth in claim 2, wherein said torque cut-off mechanism comprises a driving member having a plurality of circumferentially curved surface portions, a driven member having axially tapered grooves at portions of its inner periphery, the number of said groove being equal to the number of said curved surfaces, and balls interposed between said curved surfaces and grooves.
4. An electrically powered torque-controlled tool as set forth in claim 1, wherein said clutch comprises claw means on the front end surface of a driven member axially slidable on a driving member which receives a drive force from the electric motor, a claw receiver having claws meshing with said claw means, a bit holder inserted in said claw receiver and fitted in the driving member, and means for coupling said bit holder and said claw receiver together in the direction of rotation while allowing slide movement thereof.
5. An electrically powered torque-controlled tool as set forth in claim 4, wherein said coupling means comprises a plurality of balls arranged in a plurality of rows, and said balls smooth the slide movement of the claw receiver.
6. An electrically powered torque-controlled tool as set forth in claim 1, wherein said lock mechanism comprises a lock cam inserted in the central hole of a bit holder fitted in a driving member receiving the drive force of the electric motor, a spring interposed between said lock cam and said driving member, and a lock member held in said bit holder.
7. An electrically powered torque-controlled tool as set forth in claim 6, wherein said lock member comprises two balls which are in rolling contact with each other and retained in said bit holder so that the lock action is made smooth.
8. An electrically powered torque-controlled tool comprising:
an electric motor which is a drive source;
a switch for starting and stopping said electric motor;
a clutch installed between said electric motor and a bit so as to permit interruption and continuation of the transmission of rotation between the both;
a torque cut-off mechanism adapted to act on said clutch when the torque by the bit reaches a preset torque to thereby cut off the driving force from the electric motor to the bit;
a lock mechanism for holding said clutch in its disengaged state at the cut-off time;
a switch operating mechanism adapted to transmit the action of said torque cut-off mechanism to said switch;
a torque adjusting mechanism for said torque cut-off mechanism; and a sheathing case.
an electric motor which is a drive source;
a switch for starting and stopping said electric motor;
a clutch installed between said electric motor and a bit so as to permit interruption and continuation of the transmission of rotation between the both;
a torque cut-off mechanism adapted to act on said clutch when the torque by the bit reaches a preset torque to thereby cut off the driving force from the electric motor to the bit;
a lock mechanism for holding said clutch in its disengaged state at the cut-off time;
a switch operating mechanism adapted to transmit the action of said torque cut-off mechanism to said switch;
a torque adjusting mechanism for said torque cut-off mechanism; and a sheathing case.
9. An electrically powered torque-controlled tool as set forth in claim 8, wherein said torque adjusting mechanism comprises a casing surrounding said torque cut-off mechanism, said clutch and said look mechanism, a plurality of pins slidably inserted in the end of said casing, and a nut abutting against the front ends of said pins and threadedly coupled with said casing, the arrangement being such that the movement of the nut causes the rear ends of the pins to adjust the amount of compression of a torque spring.
10. An electrically powered torque-controlled tool as set forth in claim 8, wherein the outer surface shape of the sheathing case is formed with two symmetrically curved surfaces.
11. An electrically powered torque-controlled tool as set forth in claim 8, wherein the sheathing case has a slope gradually thickening from the electric motor covering portion to the front end.
12. An electrically powered torque-controlled tool comprising:
an electric motor;
a planetary gear type speed-reduction mechanism;
a switch for starting and stopping said electric motor;
a clutch installed between said electric motor and a bit so as to permit interruption and continuation of the transmission of rotation;
a torque cut-off mechanism adapted to act on said clutch when the torque by the bit reaches a preset torque to thereby cut off the driving force from the electric motor to the bit;
a lock mechanism for holding said clutch in its disengaged state at the cut-off time;
a switch rod extending centrally through said electric motor and said planetary gear type speed-reduction mechanism to transmit the action of the torque cut-off mechanism to aid switch; and a sheathing case covering all said members;
wherein the front bearing means for the electric motor, the planet gears of the planet gear type speed-reduction mechanism, the switch rod, and the sheathing case are made of an electrically non-conductive material, whereby the exposed parts are electrically insulated.
an electric motor;
a planetary gear type speed-reduction mechanism;
a switch for starting and stopping said electric motor;
a clutch installed between said electric motor and a bit so as to permit interruption and continuation of the transmission of rotation;
a torque cut-off mechanism adapted to act on said clutch when the torque by the bit reaches a preset torque to thereby cut off the driving force from the electric motor to the bit;
a lock mechanism for holding said clutch in its disengaged state at the cut-off time;
a switch rod extending centrally through said electric motor and said planetary gear type speed-reduction mechanism to transmit the action of the torque cut-off mechanism to aid switch; and a sheathing case covering all said members;
wherein the front bearing means for the electric motor, the planet gears of the planet gear type speed-reduction mechanism, the switch rod, and the sheathing case are made of an electrically non-conductive material, whereby the exposed parts are electrically insulated.
13. An electrically powered torque-controlled tool as set forth in claim 12, wherein said electric motor being provided with a fan at the rear end and having bearing means with ventilating holes, said sheathing case surrounding the front bearing means of said electric motor with a clearance therebetween and having ventilating holes at a position facing the outer periphery of said fan.
14. An electrically powered torque-controlled tool comprising:
an electric motor;
a switch for starting and stopping said motor;
a torque cut-off mechanism comprising a driving member receiving the driving force of said electric motor, a driven member axially slidable on said driving member, and cam means disposed between said two members, the arrangement being such that when a preset torque is reached, said mechanism produces a camming action to move said members axially from each other;
a rotatable and slidable bit holder fitted in said driving member and having a spring interposed therebetween;
a clutch comprising a claw receiver slidable on said bit holder and having at the rear end surface thereof claws engageable with claws provided on the front end surface of said driven member, means for rotation-wise coupling said bit holder and said claw receiver, and a spring interposed between the ring of said bit holder and said claw receiver;
a lock mechanism comprising a lock cam inserted in the central hole. of said driving member and bit holder and having a spring between itself and said driving member, means for controlling the forward movement of said lock cam, and balls held in said bit holder and interposed between said lock cam and said claw receiver;
a switch rod abutting against the rear end surface of said lock cam and leading to said switch;
a torque adjusting mechanism comprising a casing including the bearing means of said bit holder, pins slidably inserted in the end of said casing, and a nut abutting against the front ends of said pins and threadedly coupled with said casing;
a torque spring acting between said driving member and said pins; and a sheathing case surrounding the whole;
the arrangement being such that the backward movement of the bit holder starts the electric motor and that when a preset torque is reached, the torque cut-off mechanism is actuated, the lock mechanism is actuated and the motor is stopped by the movement of the switch rod.
an electric motor;
a switch for starting and stopping said motor;
a torque cut-off mechanism comprising a driving member receiving the driving force of said electric motor, a driven member axially slidable on said driving member, and cam means disposed between said two members, the arrangement being such that when a preset torque is reached, said mechanism produces a camming action to move said members axially from each other;
a rotatable and slidable bit holder fitted in said driving member and having a spring interposed therebetween;
a clutch comprising a claw receiver slidable on said bit holder and having at the rear end surface thereof claws engageable with claws provided on the front end surface of said driven member, means for rotation-wise coupling said bit holder and said claw receiver, and a spring interposed between the ring of said bit holder and said claw receiver;
a lock mechanism comprising a lock cam inserted in the central hole. of said driving member and bit holder and having a spring between itself and said driving member, means for controlling the forward movement of said lock cam, and balls held in said bit holder and interposed between said lock cam and said claw receiver;
a switch rod abutting against the rear end surface of said lock cam and leading to said switch;
a torque adjusting mechanism comprising a casing including the bearing means of said bit holder, pins slidably inserted in the end of said casing, and a nut abutting against the front ends of said pins and threadedly coupled with said casing;
a torque spring acting between said driving member and said pins; and a sheathing case surrounding the whole;
the arrangement being such that the backward movement of the bit holder starts the electric motor and that when a preset torque is reached, the torque cut-off mechanism is actuated, the lock mechanism is actuated and the motor is stopped by the movement of the switch rod.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP056960/1977 | 1977-05-16 | ||
| JP5696077A JPS608195B2 (en) | 1977-05-16 | 1977-05-16 | electric screw driver |
| JP131723/1977 | 1977-11-01 | ||
| JP52131723A JPS582036B2 (en) | 1977-11-01 | 1977-11-01 | electric screw driver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087885A true CA1087885A (en) | 1980-10-21 |
Family
ID=26397966
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA302,910A Expired CA1087885A (en) | 1977-05-16 | 1978-05-09 | Electrically powered torque-controlled tool |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4265320A (en) |
| CA (1) | CA1087885A (en) |
| GB (1) | GB1568952A (en) |
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| SE461510B (en) * | 1986-11-27 | 1990-02-26 | Atlas Copco Ab | ACTIVATION ARRANGEMENTS FOR ELECTRIC SCREW CARRIER |
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| US10934773B2 (en) * | 2012-06-13 | 2021-03-02 | Somfy Activites Sa | Motorized manoeuvring device intended to manoeuvre a moving windable fabric screen of a window or projection screen cover device |
| FR2992142B1 (en) | 2012-06-13 | 2014-07-11 | Somfy Sas | ELEMENT FOR SUPPORTING A BATTERY IN A WINDOW TUBE OF A DOMOTIC SCREEN |
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| US4078618A (en) * | 1976-03-15 | 1978-03-14 | Gardner-Denver Company | Torque controller shutoff mechanism |
-
1978
- 1978-05-04 US US05/902,867 patent/US4265320A/en not_active Expired - Lifetime
- 1978-05-09 GB GB18471/78A patent/GB1568952A/en not_active Expired
- 1978-05-09 CA CA302,910A patent/CA1087885A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4265320A (en) | 1981-05-05 |
| GB1568952A (en) | 1980-06-11 |
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| MKEX | Expiry |