CA1311677C - Automatic wheel attachment apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An automatic wheel attachment apparatus for attaching a wheel to a wheel attachment member of an automotive body. The automatic wheel attachment apparatus includes a reorienting device for reorienting a wheel attachment surface of the wheel attachment member, a phasing device for phasing wheel attachment bolts on the wheel attachment member, the phasing device being movable longitudinally and vertically of the automotive body to bring the wheel attachment member and the phasing device into central alignment with each other, a detecting device for detecting the amount and direction of movement of the phasing device, and a nut runner for fastening the wheel to the wheel attachment member while the center of the wheel attachment member as detected by the detecting device is being held in alignment with the center of the wheel. At least the reorienting device, the phasing device, and the detecting device are combined in a single robot. The automatic wheel attachment apparatus also includes a wheel gripping device for gripping the wheel with at least three gripping fingers under equal forces, and a wheel positioning device for positioning the wheel before it is brought into a wheel attachment position.

Description

1 3 1 1 ~) 7 7 AUTOMATIC WHEEI, ATTACHMENT APPARATUS

3BAC}CGROVND OF THE INVENTION
41. Field of ~he Invention:
5The present inv~ntion rela~es to an automatic 6 ~heel attachment apparatus for automatically attaching 7 wheels to an automotive body, and more particularly to a 8 robot in such an automatic wheel attachment apparatus for g reorienting a wh~el attachment mem~er or hub, phasing wheel attachment bolts on the wheel attachment member, and 11 positionally detecting the wheel attachment member.
12 2. Description of the Relevant Art:
13 One conventional apparatu~ for automatically 14 mounting wheels on an automotive body is disclosed in 1~ Japanese ~aid-Open Patent Publication No. 60-42521 16 publi~hed March 26, 1985.
17 The disclosed automatic wheel attachment 18 apparatus include a robot mounted on an attachment base 19 and movable transversely (X direction), longitudinally ~Y
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2~ direction), and vertically ~Z direction) of the automotiYe 21 body by respe~tive driver mechanisms. The robot is also 22 ~wingable to meet the toe-ln angle (~) and the camber angle 23 l~) o~ a hub. The robot is thus singly capable of 24 performing varlous phases of operation ranging from the :detection o~ the hub position to the attachmen~ of a wheel ~26 to the hub.

27 In the conventional apparatus, the wheel~ are , :

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' . -1 in~talled on the automotive body with the hubs (automotive2 body) used aR a po~itional reference, except when the hub 3 bolts are phased. Therefore, the robot must be angularly 4 moved ln the X, Y, Z direcitons and al~o in directions to S meet the toe-in angle ~) and the camber angle (r~. A~ a 6 re~ult, the apparatus reguires a total of slx control axes 7 about which the robot ~hould rotate, resulting in a complex 8 mechanism and a lo~er degree of reliability.

9 SUMMARY OF T~E INVENI'ION
~cc~rding to the pre~ent invention, an automotive 11 body transferxed by a feeding device iR ~upported by a 12 supporting device at a wheel attachment position, in which 13 a hub i~ reorlented on the basis of a robot reference, and 14 then hub bolts are phased and the hub is positionally detected. Thereafter, a wheel is attached to the hub by a 16 nut runner installed on or separate from a robot.
17 According to the present inv~tion, there i 18 provîded an automatic wheel attachment apparatus for 19 attaching a wheel to a wheel attachment member of an automotive body, the wheel attachment member having a wheel 21 attachment ~urface with wheel attachment bolts thereon, the 22 automatic wheel attachment apparatus co~pri~ing a 23 reorienting device for reorienting a wheel atta~hment 24 ~urfac of the wheel attachMent member, a phasing device for phasin~ the wheel attachment bolts, the phasing device 26 being movabl~ longitudinally and vertically of the 27 automotive body to bring the wheel attachment member and .~ .

1 ~ I 1 677 1 the phasing device into central alignment with each other, 2 a detecting device for detecting the amount and direction 3 of movement of the pha~ing ~evice, a nut runner or 4 fastening the wheel to the wheel attachment member while the center of the wheel attachment ~ember a~ detected by 6 the detecting device is being held in alignment with the 7 center of the wheel, and at least the reorienting device, 8 the phasing device, and th~ detecting device being combined 9 in a single robot.
The reorienting device, the phasing device, and 11 the de ecting device ~r~ mounted in one portion of th~
12 robot, and the nut runner is mounted in another portion of 13 the robot, the portions of the robot being supported on a 14 common shaft, the robot being arranged su~h that one of the portions confronts the wheel attachment member by rotating 16 the shaft.
17 The phasing device comprises a pair of phasing 18 finger3 movable toward ea~h other with the wheel attachment 19 bolts therebetween, and a mechanism for releasing the wheel attachment bolts from dead point~ of the phasing fingers, 21: the mechanism including ~ rotatable tube rotatable about 22 the center of the phasing device, and engaging members held 23 by the rotatable tube for engaging the wbeel attachment 24 bolt5, the engaging members being ro atable with the rotatable ube and movable toward the wheel attachment 26 member at respec~ive speeds:selected such that ~he engaging 27 members traverse the dead points of the phasing fingers .,.. ,.. ,.. ,, :

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1 ~ 1 1 677 1 while the engaging members are being positioned ~o closely 2 tv the wheel attachme~t m~mber as to engage the wheel 3 attachment bolt~.
4 The nut runner comprises a plurality of socket~
for holding nuts to be tightened over the wheel attachment 6 bolts, a plurality of motor~ for rotating the eockets 7 respectlvely, a plurality of drive shafts coupled to the 8 motors, respectively, and a plurality of univer~al joints 9 connectlng the ~ockets and the drive shafts while allowing the sockets to be tilted with respect to the drive shafts, 11 the univer~al joint~ being movable axially of the drive 12 shafts to allow the sockets to be retracted under reactive 13 force~ produced when the nuts engage the wheel attachment 14 bolt~.
The automatic wheel attachment apparatus also 16 includes a wheel gripping device cooperating with the nut 17 runner, the wheel ~ripping device comprising at least three 18 cylinders independently actuatable to produce equal forces, 19 a plurality of fingers coupled respectively to the cylinder unit~ for pre~ing engagement with an outer tire of the 21 wheel which is pre-positioned, and fixi~g means for keeping 22 the finger~ in pressing engagement with the tire.
23 The automatic wheel attachment apparatus ~urther 24 includes a wheel positloning device cooperating with the wheel gripping:device, the wheel positioning device ~2~ co~pri8ing a head vertically movably suppor~ed below the :27 wheel wh~h i~ tran~ferred in horizontal attitude, a _ 4 _ :~ :

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1 rotatable member rotatably di~po~ed in the head, a 2 central~zer di~posed in a di~tal end of the rotatable 3 member and fittable into a cen~ral hole of a wheel center 4 of the wheel in xe~pon3e to upward movement of the head, a 5 clamp member for engaging the wheel center while the 6 centralizer i5 fitted in the central hole, and a pin 7 mounted Oh the head and engageable in a bolt attashment 8 hole in the wheel center when the bolt attachment hole 9 reache~ a prescribed position upon rotation of the wheel by the rotatable member.
ll ~he above and further obj~ctR, ~tAils and 12 advantageq o~ the present inventlon will become appa~ent 13 from the following detailed description of a pre~erred 14 embodiment thereof, when read in conjunction with the accompanying drawing~.

16 BRIEF DESCRIPTION OF T~E DRI~.WINGS
17 ~IG. 1 is a plan ivew of an automatic wheel 18 attachment apparatus incorporating robots according to the l9 pre~ent invention;

FIG. 2 i~ a side elevational view of the 21 automatic wheel attachment apparatus, with an automotive 22 ~ body bein~ viewed in front elevation;

23 FIG. 3 is a front elevational view of the 24 automatic wheel attachment apparatus, with the automotive 2S body being viewed in si~e ele~ation;

26 FIG. 4 i~ a verticaI cross-sectional view of a 27 ~ wheel posltioning device;

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PIB~ 5 i~ a plan Yie~ of the wheel po~itioning 2 devi~e:
3 FIG. 6 1~ a side elevational view, partly in 4 cross ~ection, of an automotive body ~upporting device;
FIG. 7 i~ a bottom view o~ a flo~ting table;
6 FIG. 8 is a front elevational view o~ a hu~
7 reorienting device ~nd a hub bolt phasing device on a wheel 8 a~tachment robot~
9 FIG. 9 is a side elevational view of the hub reorienting device and the hub bolt phasing device a~
11 viewed in the direction of the arrow IX in FIG. 8;
1~ FIG. 10 is a rear elevational view o the robot;
13 FIG. 11 i~ a fragmentary side elevational view of 14 thr robot as ~-iewed in a direction oppo~ite to the direction ln which FI~. 9 ie viewed;
16 FIB. 12 is a cross-sectional view of the hub bolt 17 pha~ing device as viewed in the direction of the arrow XII
18 in FIG. 8;
19 FIG. 13 i~ a front elevational view showing the manner in which the hub bolt phasing de~ice operate~;
21 FIGS. 14 and 15 are fragmentary views of a 22 me~hanism for operating the hub bolt phasing dPvi~e;
23 FIGS. 16~A) through 16~C) ~re plan view~
4 explaining~the priDciple of angularly correc~ing or ~ reorienting hubs;
~26 FIG. 17 is a fragmentary bottom view~of a ~heel ~27 ~ripping device;

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1 ~IG. 1~ i~ a fragmentary side elevational view of 2 the wheel grippiny device;
3 FIG. 19 is a cros3-~ectional view of the wheel 4 gripping device as ~iewed in the ~irection of the arr~w XIX
in FIG~ 18;
6 FIG. 2G i~ a view, partly in cro~s section, of a 7 gripper o~ the wheel s~ripping device 8 FIG. 21 i~ a cross-~ectional view of a nut 9 runne~;
FIG. 22 is a partly cross-sectional view taken 11 along line XXII - XXII of FIG. 21; and 1~ FIGS . 23 (A) through 23 (C ) are cross-~ectional 13 views showing the manner in which a nut held in a socket of 14 the nut runner is axially aligned with a hub bolt.
DET~ILED D~SCRIPTION OF THE PREFERRED EMBO~IMENT
16 A4 shown in FIGS. 1 through 3, an automatic wheel 17 attachment apparatu3 1 comprises a plurality of devices, 18 i.e., a conveyor device 3 ~FIGS. 1 and 2) for delivering 19 wheels S ln horizontal attitude to an automotive body 2, wheel po8itioning device~ 36 (FIGS. 1 through 3) each for 21 po~ltion~Dg the center of a delivered wheel W and for 22 phasing hub bolt attachment hole~ of the wheel W, an 23 intermittent feeding devi~e 4 for intermittently 24 transferring the automotive body 2 to a wheel attachment po~ition and for transferring the auotmotive body 2 with 26 wheels W attached to a next processing station, a ~2~ : ~upporting device 5 (FIGS. 2 and 3) for floatingly :: ;

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~1 1677 1 ~upporting the automotive body 2 in the wheel attachment 2 position, and robots 100 each for effe~ting variou~ modes 3 of operation rangin~ from the po~itioning of A wheel 4 attachment member or hub 6 on the automo~ive body 2 to the attachment o~ a wbeel W to the hub 6.
.6 The~e various devices of the automatic wheel 7 attachment apparatus 1 will be described belo~ in detail.
a The conveyor devire 3 comprises a main conveyor g 30, subconveyor~ 31 branched perpendicularly rom the main conveyor 30, and subconveyors 32 branched perpen~icularly 11 from the ~ubconveyors 32 and extending laterally to the 12 automotive body 2. Each of the conveyors 30, 31, 32 has a 13 number of longer rsller~ 33 and a number of shorter rollers 14 34 position~d at branched areas for changing the direction of travel of wheels W. When four wheels W, for example, 16 are delivered on the main conveyor 30, they are.separated 17 into two'~ which are fed onto tbe subconveyors 31, from 18 which the wheels W are transferred onto the ~ubconveyors 19 32, respectivelyO
The wheel~ W transferred onto the respective 21 subconveyors 32 are then supp1ied to the respective wheel 22 positioning devices 36 which are located adjacent to the 23 eDds of the ~ub~onveyor~ 32. Each of the wheel po~itioning : 24~ devlc~s 36 positiono the center of the whe~l W and phases : 25 hub bolt insertion or attachment holes of the wheel W, 26 Thereafter, the wheels W are held by the robots 100 and 27 attached thereby to the respective hubs 6 of the automotive :
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` 131 1677 1 body 2.
2 The wheel po3itioning device 36 will be de~cribed 3 with reference to ~IGS. 4 and 5. The wheel posi~ioning ~ device 36 i8 disposed between laterally ~paced roller~ 35 ~f the ~ubconveyox 32. The rollers 35 are supported on S re~pective column~ 51 on which a base 53 of the wheel 7 positioning device 36 i~ vertically movably mounted.
O The bz~ ;3 i3 vertice~lly mo~Able b~r ~ cylind_r 9 unit 54 and has an upper portion to which a head 55 is secured. ~ vertical hollow rotatable shaft S6 extends 11 centrally through the head 55 and is rotatable by a motor 12 57 mounted on a lower portion oP the head 55. The hollow 13 shaft 56 has on its upper end a centralizer 58 projecting 14 upwardly from the upper surface of the head 55. A rod 59 extend~ through the centralizer 58 and the hollow shaft 57 16 and is rotatably coupled through a joint 61 to a ~ylinder 17 unit 60 mounted on the base S3. The rod 59 is ~hus 18 vertically movable in the bollow shaft 57 by the cylinder l9 unit 60. ~ plurality of radial clamp fingers 63 are movably supported on an upper head 62 disposed in the 21 centralizer 58 of the rod 59. The clamp fingers 63 extend 22 respectively through inclined holes 64 defined in an upper 23 end portion of the hollow shaft 56 and project Oue of the 24 3haft 56. Pins 65 are disposed in the respective inclined holes 64 and enga~e re~pectively in slots 66 defined in the 26 respective clamp ~ingers 63.
27 When the rod 59 is lowered by the cylinder unit _ g _ ,~,,. , ' ~

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131 ~677 1 60, the clamp ingers 63 project out of the inclined h~les2 64 into abutment ~galn3t the inner surface of a central 3 hole 13 of the wheel center 11 of the wheel W thereby to 4 ~ecure the wheel W to the shaft 56.
~our positioning pin~ 67 which are equally 6 an~ularly 6paced around ~he shaft 56 are d1spo~ed in the 7 head 55. The po~itioning pins 67 are normally urged by 8 springs 6~ to move upwardly so tha~ ~he upper end~ of the g pin3 67 project upw~rdly beyond the upper surface o~ the head 55.
11 The wheel positioning device 36 thus constructed 12 operates a~ ~ollow~:
13 The wheel W which ha3 been delivered from the 14 main conveyor 30 and the subconveyor 31 onto the subconveyor 32 is stopped and held by holder arms 69 ~FIG.
16 1 ) . At this ~ime, the head 5~ of the wheel po~itioning 17 device 36 i8 poaitioned downwardly of the rollers 35.
18 Then, the cylinder unit 54 is actuated to bring 19 the centralizer 58 on the upper end of the hollow shaft 56 into the central hole 13 o~ the wheel W, whi~h is then 21 lifted off the roller 35 by the head 55. If the 22 positionin~ pin~ 67 enter the hub bolt attachment holes 12 23 of the wheel 11 when the wheel W is lifted, the hub bolt 2~ attachment holes 12 have properly been phased. ~owever, the hub bolt attachment hsle~ 12 and the pins 67 are : 26 usually out of alignment, and hence the upper e~ds of the : 27 positioning pin~ 67 engage the lower sur~ace of the wheel :

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---" 1 31 1 677 1 11 but not enter the hub bolt attachment hole~
2 The cylinder unit 60 is operated to lower the rod 3 S9. The clamp fingers 63 are pulled out and ~pread to 4 cause their distal ends to engage the inner ~urface of ~he central hole 13 of the wh~el 11 for thereby ~ixing the 6 wheel W to the sha~t ~6. Then, the motor 57 i~ energized 7 to rotate the hollow shaft 56 through meshing gears 70, 71 8 to rotate the wheel W until the hub bolt attachment holes 9 12 and the po~itioning pins 67 are aligned with each other, whereupon the positioning pins 67 project into the 11 re~pective hub bolt attachment holes 12 under the 12 re~ ncy of the springs 68. Upon detecting the insertion 13 of the positioning pins 67 into the hub bolt attachment 14 ~ S 12, the mo'cor 57 i~ de-~:ncrgi~cd to ~:top tha rotation lS of the shaft S6. Thereafter, the wheel W will be gripped 16 by a wheel gripping device of the robot 100, as des~ribed 17 later.
18 While in the illustrated embodiment the pin~ 67 19 are forced by the springs ~8 to proje~t into the hub bolt attachment hles 12 of the wheel 11, a cylinder unit may be 21 employed in place of ~he spring~ 68. More specificallyr at 22 the time a sensor detect~ when the hub bolt attachment 23 ~ hole~ 12 are positioned immediately above the positioning 24 pins 67, the motor 57 i8 de-energized, and the ~ylinder unit i~ operated to insert the positioning pins 67 into the ~26 re~pective hub bolt attachment hole~ 12 to pha~e them.
; 27 The wheel po~itioniny device 36 can position and :

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I ~ 1 1 677 1 phaRe a wheel while it i9 held in a horizontal attitude.
2 Thus, the mechani~m for hol~ing the wheel i8 quite simple 3 and any conven.itonal device ~or inverting the wheel is not 4 re~ulred. Since ~he wheel po~itioning device 36 can be incorporated in the wheel conveyor r it is a ~pace 8aver .
6 A~ ~hown in FIG. 3, the intermittent feeding 7 device 4 ha~ a propelling body 41 movable by a motor or the 8 like is movably moun~ed on a rail 40 hung from a ceiling, 9 and a cantilevered hanger 42 supported on the propelling body 41, the automotive body 2 i9 s~pported on the hanger 11 42 for intermittent feeding along the rail 40.
12 The supporting device 50 which supports, in the 13 wheel attachment position, the automotive body 2 that has 14 been delivered by the intermittent feeding device 4 is illu~trated in detail in FIGS. 6 and 7.
The supporting device ~ has guide receivers 81 17 vertically mounted on a base 80 and guide rods 83 fixed to 18 a lifter base 82 and vertically movably inserted through 19 the guide receivers 81. A cylinder unit 84 fixed to the base 80 has a rod ~ with its upper end secured to the 21 lifter ba~e 82 30 th~t the lifter base 82 can be moved 22 upwardly and downwardly in response to operation of the 23 cylinder unit 84.
24 Air bearings 86 are disposed on the respective 25: four corners of the upper ~urface of the lifter base 82.
26 ~ table 87 is placed on the air bearings 8~. ~ore : 27 specifically, each of the air bearings 86 comprise a pip~

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--`-` 1 3 1 1 677 l ~8 connected to a ~ource of compressed air and a ~hallow 2 bearlng ~eat 89 mounted on the upper end of the pipe 88, 3 the upper ~urface of the bearing seat 89 being closed by a 4 smooth flat plate 91 attached to the lower surface of the table 87.
6 A~ ~hown in FIG. 7, the lower surface of t~e 7 bearing seat 89 has front, rear, and lateral thi~k portions 8 89a ex~ending radially outwardly from the pi~e B8. ~ollers 9 92 mounted on the lo~er surface of the smooth flat plate 91 are held against the outer ends of the fr~n~ and rear thick ll portion~ 89a~ Coil ~prings 95 are coupled between pins 93 12 on the four corners of the lower surface of the smooth flat 13 plate 91 and pin~ 94 disposed around the central pipe 88 of 14 the air bearing 86 for normally urging the smooth flat plate 91 and the air bearin~ 86 to be centrally aligned 16 when no force is ~pplied to the smooth flat plate 91, i.e., 17 the table 87.
18 A pin 43 i8 a~fixed to the hanger 42 (shown ln l9 cro~ ~ectlon in FIG. 61 of the feeding device 4. The table 87 ha~ a tube 96 mounted on its front portion, the 21 pin 43 bein~ inserted in the tube 96. The tube 96 has a 22 hole 96a in which a rod 98 of a cylinder unit 97 ~i~ed to 23 ~he table B7 i5 ingerted.
24 When the table 87 is lifted by the cylinder unit 84, the tube 96 is fitted o~er the pin 43 of the hanger 42.
26 As the pin 43 i~ relatively inserted into the tube 96 ~or a 27 pre~cribed interval, an actuator 44 on the hanger 42 ;~ ~ 13 -' .
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1 operate~ a 11mit ~witch 90b attached to the table 87 for 2 enabllng the rod 98 of the cylinder unit 97 to project.
3 Tbe dietal end of the rod 98 engages in a rece~s of the pin 4 43 to ~ecurely position the ~utomotive body 2 on the table 87. The pin 43 hou~es a 3pring 45 therein for dampening 6 any shocks wh$ch are prod~lced when the lower end of the pin 7 43 hits the upper ~urface of the smoo~h flat plate 91.
8 With the automotive body 2 fixed to the table 87, 9 the bearing ~eat~ 89 of the air bearin~s 86 are supplied with compressed air. Since the upper ~urfaces of the 11 bearing 3eat 89 are closed by the respec:tive ~mooth flat 12 plate~ 91, the table 87 i8 movably supported in a 13 horizontal plane on the air bearings 86. Inasmuch aq the 14 rollers 92 fixed to the ~mooth flat plates 91 are held against the front ~nd rear thick portion~ 89a of the air 16 bearinge 86, however, the table 87 is floatingly ~upported 17 while being permitted to move only in ~he transverse 18 direction of the automotive body 2. This floatin~ support 19 of the automotive body 2 make~ it possible to eliminate any tran~verse po~itional error of the hub 6 on one side of the 21 ; automotive body 2 and also to el$minate any angular error 22 of the hub 6 on the other side of the automotive body 2, as 23 described later on.
24 Each of the robot~ 100 will hereinafter be 25 de~cribed in detail .
26 A~ illustrated in FIGS. 2 and 3, the robot 100 is 27 ~upported on a ba~e 101 which i~ movable by a cylinder unit : - 14 -':

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1 102 in the longltudinal direction of the a~tomotive body 2.
2 A po t 103 i~ vertically mounted on the base 101, and a box 3 104 housing a motor and other p~rts therein i9 mounted on 4 the upper e~d of the po~t 103. The box 104 i9 vertically movable by a cylinder unit 105, the box 104 ~upporting a 6 shaft 106 rotatable by the motor in the box 10~. The ~haft 7 106 ~upports thereon a unit A for reorienting the hub 6 and 8 phasing the hub bolts, and a unit B for holding ~he wheel W
9 and attaching the wbeel W to the hub 6, the units ~, B
being angularly spaced 90 about the shaft 106. The unit B
11 i~ vertically movable by a cylinder unit 107.
12 Upon rotation of the shaft 106 through 90 in the 13 direction of the arrow in FIG. 2, the unit A which has 14 completed the reorientation of the hub 6 and the phasing of the hub bolt~ is turned upwardly away from the hub 6, and 16 the unit ~ carrying the w~eel W i~ angularly moved up to 17 the hub 6.
18 The unit A will first be described with reference 19 to FIGS. 8 through 16. The unit A comprise~ a device 200 for reorientin~ the hub 6 ana a device 300 for phasing the 21 hub bolts. As shown in FIGS. 8 and 9, the reorienting 22 dev~ce 200 includes a cylinder unit 202 mounted laterally 23 on a ~upport plate 201 and having a rod 203 fixed to a ~4 plate 205 slidably supported on two guide rods 204, with a pair of reorlenting bars 206 attached to the plate 205. As 26 ~hown in FIG. B, the reorienting bar~ 206 are progressively 27 ~pread away from each other, and movable toward and away 1 ~1 1 677 1 from the hub 6 by the cylinder unit 202 independently of 2 the pbaslng device 300.
3 The proce~ of reorienting the hub 6 With the 4 correcting device 200 wlll be described also with reference to FIGS. 16~A) through 16(C). The proce~s of reorientati~n 6 of the hub 6 i8 to control the hub 6 so that it~ positional 7 error in the transverse direction of the automotive body 2 8 and it~ angular error will fall within an allowable error 9 range, with the re~ult that nuts can reliably be tightened on the hub bolts on the hub 6 by a nut runner, described 11 later.
12 FIG. 16~A) shows in plan view the relationship 13 between a front portion of the automotive ~ody 2 that has 14 been fed by the feeding device 4 and the reorienting devices 2000 In the position of FI~. 16(~1, the 16 reorienting bar~ 206 of the lefthand and righthand 17 reorlenting devices 200L, 200R are spaced from the lefthand 18 and righthand hub~ 6L, 6R. The hubs 6L, 6R which are not 19 yet reoriented are po~itionally displaced x mm fro~ their original po~ition in the trans~erse direction of the 21 automG~ive body 2, and are angularly displaced . The 22 hubs 6 are always subjected to a positional error and 23 angularly displaced when the hub 6 i~ installed on a 24~ ~nuckle or during transfer of the automotive body 2. If one of the hubs, e.g., the righthand hub 6R, had a 26 positio~al error and an angular error in a concentrated ~7 manner, then ~uch combined errors are ~o large that pha~ing ~ ' 131 1~77 l fingers 317 9 319 of the phasing device 300 may not engage 2 hub bolts 60 or nut may not be tightened by ~ ~ut runner 3 500.
4 According to the present invention, the reorientin~ b~rs 206 of one of the reorienting device~ 200R
6 can project to a fixed e~tent, wherea~ the reorientin~ bars 7 206 of the oth~r reorienting device 200L can project to an 8 extent which is possible. More specifically, the 9 reoxienting bars 206 of the righthand reorienting device 200R project a fixed distanc2 toward the hub 6R and then ll stops, and the reorienting bars 206 of the lefthand 12 reorienting device 200L project until they abut against the 13 hub 6L aDd are ~topped thereby.
14 As shown in FIG. 16(B), the reorienting bars 206 of the reorlenting device 200R are first caused to project 16 a fixed amount into abutment again~t the righthand hub 6R.
17 Since the automotive body 2 i~ floatingly supported in the 18 transverse direction, the automotive ~ody 2 is transversely 19 pushed by the reorienting bar~ 206. ~ow, the po~itional error and angular error of the righthand hub 6R are 21 eliminated, and any transversely positional errGr and 22 angular error are all concentrated on the lefthand hub 6L.
23 Tbereafter, as ~hown in FIG. 16(C), the 24 reorienting bar~ 206 of the lefthand reorienting de~ice 200~ are forced.to project until they abut against the 26 lefthand hub 6~ to ellminate the angular error of the the 27 hu~ 6Lo ~owever, since the righthand hub 6R is engaged by : .
~ 17 -1 the reorientlng bars 206 of the righthand reorientiny 2 device 200R, any positlonal error of the lefthand hub 6~ in 3 the tran~ver~e direction of the automotive body 2 remain~.
4 Sub~equently, the reorienting bars 206 of the righthand reorienting device 200R ~re retracted out of 6 engagement wlth the righthand hub 6R, and then the 7 reorienting bar~ 206 o~ the lefthand reorienting device 8 200L are retracted out of engagement with the lefthand hub 9 6L. When the reorienting bars 206 of the ri~hthand reorlenting device 200R are retracted first, the righthand 11 hub 6R i~ ~ub~ected to an angular error. When the 12 reorienting bar~ 206 of the lefthand reorienting device 13 200L are thereafter retracted, no angular error is produced 14 on the lefthand hub 6L.
A~ter the above reorienting proces3, the 16 righthand hub 6R i8 subjected to an angular error only, 17 wheraa~ the lefthand hub 6L is subjected to a positional 18 error only, with the result that no combined effect of 19 these angu~ar and positional errors is produced on each of the hubs. Therefore, phasing fingers can reliably be 21 bro~ght into engagement with the hub bolts in a subsequent 22 phasing process, ana nut~ can reliably be tightened on the 23 hub bolt~ without fail.
24 The reorienting bars 206 of one of the reorlenting devices 200 project to a fixed inter~al, 26 wherea~ the reorienting barq 206 of the other reorienting ~7 devi~e 200 project untll they are ~topped. ~hus, it i8 not - 18 ~

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1 ~ece~ary to detect how the reorienting bars 206 has 2 projected e~ch t~m~ the hub is reoriented, unlike the 3 conventional apparatu~ in which the amount o~ movement o~ a 4 wheel attachmen~ robot must be detected each time the hub ls reoriented. Therefore, the nu~ber of control axes is 6 reduced and the s~ructure is simpler accordiny to the 7 present invention.
8 A~ shown ln FIGS. 8 through 12, the hub bolt 9 pha~ing device 300 lncludes a base assembly 301.mounted on the support plate 201 of the unit A and supporting a pair 11 of phasing fin~ers. More spezifically, the base assembly 12 301 comprise~ a ~irst movable base 301a and a second 13 movable base 301b. ~ sho~n in FIGS. 9 and 11, the first 14 movable base 301a engage~ rails 303 attached to the support plate 20i and i8 movable horizontally in a plane parallel 16 to the wheel attacbment surface of the hub 6. The second 17 movable base 301b engage~ the first movable base 301a 18 through rails 304 and is movable vertically in a plane 19 parallel to the wheel attachment sur~ace of the hub 6. The 20 fir~t movable base 301a is horizontally moved with guite a 71 small force by horizontal balancinq cylinders 305 (FIG.
22 10), whereas the ~econd movable base 301b is vertically 23 moved with quite a small force by a vertical balancing 24 cylinder 306. The~e small forces are smaller than a force which sub~tantially deforms a resilient member such as a 26 suspe~cion, a rubber mount, or the like that is interposed 27: between th~ hub 6 and the automotive body 2.

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1 3 1 l G ~ 7 1 A3 lllustrated in FIGS. 10 and 11, clutch plate~
2 307 have ends ~wingably supported on the support plate 201.
3 A cylinder unit 309 i~ a~tsched to the upper end of an ar~
4 30a ~ntegral with the ~econd movable base 301b. The cylinder u~it 309 ha~ a rod 309a extending through an 6 oblong hole 310 defined in the clutch plates 307 with a 7 pres-ser plate 311 secured to the distal end of the rod 8 309a. As the movable bases 301a, 301b are moved, the 9 clutch plat~ 307 are angularly m3ved. Wh~n ~ho cylindcr unit 309 is operated, the clutch plate~ 307 arP ~andwiched 11 between the arm 308 and the presser plate 311 to stop the 12 movable base~ 301a, 301b. The direetion and amount of 13 movement of the movable bases 301a, 301b are detected by 14 rotary encoders 312, 313.
As shown in FIGS. 9 and 13, two pairs of 16 vertlcally extending upper and lower rails 315, 316 which 17 are vertically spaced from each other are ~ounted by posts 1~ ~not shown~ on the second movable ba3e 301b. An upper 19 phasing finger 317 ha~ it~ ba~e vertically movably mounted on the upper rails 315, and a lower phasing ~inger 319 has 21 its base vertically movably mounted on the lower rails 316.

22 The phasing ingers 317, 319 have pairs of right an~ularly 23 ~paced arms 317a, 319a, respectively, which havs thin tip 24 end portion~ 80 that when the phasing fingers 317, 319 are moved clo~ely toward each other, the tip end portions of 26 the arm~ 317a, 319a overlap each other.
~7 The pha~ing fingers 317, 319 are interconnected .
':
' 1 ~uch that they can be moved away from each other by a 2 mech~nism ~described later).
3 The phaYing finger~ 317, 319 are al~ in 4 engagement with a rotatable body 330 a~ well ~ the rails 315, 316. As ~hown in FIG. 12, the rotatable body 330 i~
6 rotatably ~ounted around a tubular body 322 having one end 7 fixedly disposed in a circular hole 3Zl defined in the 8 movable base 301b. Curved arms 323 whi~h are symmetrical g in ~hape wlth respect to the center of rotation of the rotatable body 330 extend therefrom ~only one curved arm is 11 shown in FIG. 14). The curved arms 323 have grooves 324, 12 respectively, in which rollers 325 mounted on the phasing 13 finger bases 318, 3~0 are fitted. A motor 326 i8 mounted 14 on a lower portion o~ the movable base 301b and has a rotatable shaft 327 over which a semicircular gear 328 is 16 fitted. The gear 328 is held in mesh with gear teeth on 17 the outer peripheral edge of the rotatable body 330, as 18 shown in FIGS. 12 and 15.
19 When the motor 326 i6 energized, the rotatable body 330 i8 angularly moved clock~ise in FlG. 8 until the ?1 ~urved arms 323 rea~h the po~ition indicated by the 22 imaginary line~. During ~ucb rotation, since the rollers 23 325 of the pha3ing fingers 317, 319 engage in the grooves 24 324 of tbe cur~ed arm~ 323/ the upper phasing finger 317 2S moves downwardly along the rails 315 and the lower phasing 26 finger 319 moYe~ upwardly along ~he rails 316. A~ shown in 27 FIG~ 13, the tip ends of the arms 317a, 319a of the phasing :: :

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1 s 1 1 677 1 ~inger~ 317, 319 overlap each other to form a ~iquare shape.
2 The hub bolt~ 60 of the hub 6 are positioned respective at 3 tha corner~ of the ~quare sh~pe. The hub bolts 60 of the 4 hub 6 which ha~ been reoriented by the reoriented devlce 200 ~re now pha~d.
6 The center of the hub ~ after it ha~ been 7 reoriented and the center of the pha~iing device 300 are not 8 necessarily aligned with each other, but may be di~placed 9 from each ~ther in the longitudinal and vertical directions o~ the automotive body 2. At the same ti~e that the hub 11 bolts 60 are pha~ed, poqiitional detection i~ ef~ected in 12 order to bring he center of the phasin~ device 300 into 13 alignment with the center of the hub 6. More specifically, 14 if the hub bolt~ 60 are pha~ed while the phasing device 300 and the hub 6 are out of central alignment, the hub bolts 16 60 do not abut again~it the arm~ 31?a, ~19b of the upper and 17 lower phasing device3 317, 319 simultaneou~ly, but one of 18 the hub bolts 60 abuts against one of the phasing ~inger-~19 317. Then, the movable bases 301a, 301b ~upporting the 2D phasing fingers 317, 319 are moved vertically and laterally 21 with small forces by the horizontal balanclng cylinders 305 22 and the vertical balancing cylinder 30Ç. For example, if 23 one of the hub bolts 60 first engages the upper pha ing 24 finger 317 when the motor 326 is energized to move the phaQiDg finger~ 317, 319 toward each other, the upper 26 phasing finger 317 i6 prevented from descending ~urther, 27 and the rota~able body 330 and t~e lower phasing finger 319 .

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131 1 h77 1 con~inuously a~cend, with the first movable base 301a o~
2 the phasing dev~ce 300 moving upwardly. If one of the hub 3 bolt~ 60 abut~ against one of the arms of the phasing 4 finger~ 317, 319 r the ~econd movable base 301b i8 moved hoxi70ntally. Thus, where the hub 6 and the base assembly 6 301 of the hub b~lt phasing device 300 are out o central 7 alignment with each other, the center of the base as~embly 8 301 1~ moved into alignment with the center o~ the hub 6 at 9 the ~ame time tha~ the hub bolts are being phased. After the hub bolts have been phased, the cylinder unit 309 is 11 operated to grip the clutch plates 307 to fix the movable 12 ba~es 301a, 301b in position. Thereafter, the direction 13 and amount of movement of the movable bases 301a, 301b are 14 detectea by the rotary encoder3 312, 313, and ~ignals from the rotary encoders 312, 313 indicating the detected 16 direction and amount of movement are supplied to a control 17 unit lnot shown). The control unit then ~omputes the I8 accurate position of ~he hub 6 based on the supplied 19 signal~.
When the phasing fingers 317, 319 are moved 21 toward each other to phase the hub bolts 60, the hub bolts 22 60 which are angularly spaced 45 may happen to engage the 23 dead points D.P. of the phasing fingers 317, 319, and hence ~24 the hub 6 ~ay not rotate ~n ei her direction irrespective : 25 of the fact tbat the hub bolts 60 are out of phase.
26 As shown in FIG. 12, a dead-point releasing 27 mechanism 350 is dispo3ed in the tube 322 for releasing the : :

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1 ~1 1 617 1 hub bolts 60 off the dead points of the phasing fingers ~ 317, 319.
3 The dead point relea~ing mechanism 350 includes a 4 rotatable tube 352 fixed to the rotatable shaft of a ~otor 351 and having a pair of integral arm~ 353 on its distal 6 end, the arm~ 353 having through hole~ 354 on their di~tal 7 end~ with engaging members 355 slidably inserted through 8 the holes ~54, respectively. ~ nonrotatable tube 356 i~
g dispo~ed around the rotatable tube 352 and normally urged by a sprin~ 357 toward the hub 6. ~ cylinder rod 358 11 extsnding from a cylinder unit (not shown) has it3 tip end 12 engaging the tube 3$6 to keep the tube 356 nonrotatable '!
13 even when the rotatable tube 352 is rotated. ~he tube 356 14 has a groove 359 defined in the outer periphery thereof at its di~tal end, and roller~ 360 on the engaging members 355 16 are fitted in the groove 359.
17 The dead point releasing mechanism 350 operates 18 as follows: ~hen the motor 326 is energized to move the 19 phasing fingers 317, 319 toward each other, the motor 351 is also energized to rotate the rotatable tube 352 slowly.
21 Since the tube 356 is not rotated at thi~ ti~e, the rollers 22 360 on the engaging member6 355 roll in and along the 23 groove 359 of the tube 356.
24 Upon ener~ization of the motor 351, the cylinder unit is operated to cau~e the cylinder rod 358 to move the 26 tube 3g5 along the rotatable tube 352 toward the hub 6.
27 The engaging member~ 355 are now moved toward the hub 6 ~;

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1 j 1 1 6 ~7 1 while there are being rotated by combined motion of the 2 ~otatable ~haft 352 as it i~ rotated and the tube 3~6 as it 3 is moved toward the hub 6, until finally the di~tal end3 of 4 the engaging members 355 abut against the rear ~urfaces of the pha~lng fingers 317, 319, whereupon the tubes 352, 356 6 are ~topped~
7 The ~peed of rotation of the tube 352 and the 8 speed of movement of the tube 356 are selected such that 9 during the time period in which the di~tal ends of the engaging ~embers 355 overlap the tip ends of the hub bolts 11 60 as viewed in side elevation as indicated by the 12 i~aginary lines in FIG. 12, the enga~ing members 355 13 traver~e the dead points D.P. of the phasing fingers 317, 14 319 once. With such a ~peed s~tting, even if the hub bolts 60 are exactly 45 out of phase, they can be displaced off 16 the dead points D.P. by sidewise engagement with the 17 engaging members 355 and can reliably be forcsd into the 18 corner~ of the ~quare shape formed by the pha~ing fingers 19 317~ 319 a they are brought together.
While the engagig members 355 are moving toward 21 the hub 6 and rotating, the ~istal end~ thereof may hit the 22 tip end~ of the hub bolts 60 in fa~e-to-face relation and 23 may not be able to engage the sides of the hub bolts 60.
24 In thi~ case, however, the tube 356 is resiliently 2S retracted against the force of the spring 357. Such Z6 : retracted movement of the tube 356 is then detected,:and .
27 the engaging members 355 are moved back to their original : :

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1~1 1617 1 p~sition, after which the tub~ 352 i ~lightly rotated.
2 ~hen, the ab~ve pro~ess i9 repeated ~gain. ~ccordingly, 3 the hub boltc 60 can reliably be released from the dead 4 points D.P. of the phasing fingers 317, 319 for pha~ing purpo~e.
6 As described above, the unit A o~ the r~bot 100 7 i5 composed of the device 200 for reorienting the hub 6 and 8 the devi~e 300 or phasing the hub bolt~ 60. The hub 6 is 9 f ir8t reoriented by the reorienting device 200, then the the hub 6 is positioned during the phasin~ process with the 11 automotive body 6 u~ed as a reference, and the accurate 12 position of the hub 6 which ha~ been pha~ed i~ computed by 13 the control unit. Thereafter, the wheel W is placed in 14 confronting relation to the hub 6 and attached to the hub 6 by the unit ~ ~f the ro~ot 100.
1~ The unit B of the robot 100 will hereinafter be 17 described.
18 A~ shown in ~IGS. 2 and 3, the unit ~ comprises a 19 wheel gripping dev~ce 400 ana a nut runner 500~ which i5 dispo~ed back in the center of the wheel gripping device 21 40~.
22 The whee1 gripping device 400 will be descràbed 3 `.with ~eferen~e to FIGS. 17 through 20.~ The wheel gripping:
:~24 device 400 has a pair of rail~ 402 at each of the our .corner~ o~ a support plate 401. A movable ~ody 403 engages 26:~ ea~h pair~f rail~ 402 and is fixed to a cylinder uni~ 404 27 whi~h is actuated to move the movable body 403 along the ~:
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13`1 t677 1 rails ~02. The rails 402 in each pair extend parallel to 2 e~ch other. There ~re four cylinder units 404 (40~a -3 404d) ~ecured to the ~upport plate 401 for moving the 4 re~pective movable bodie~ 403. In FIG. 17, only two cylinder units 404a, 404b are ~hown in ~helr entirety, and 6 the other two cylinder unit~ 404c, 404d are partly 7 illu trated. The cylinder unit~ 404a, 404b and the 8 cylinder unit3 404c, 404d have their axes parallel to each 9 other, and the cylinder units 404a, 404c and the cylinder units 404b, 404d have their axes aligned with each other.
11 The cylinder units 404a - 404d produce equal operating 12 ~orces.
13 As illustrated in FIGS. 18 and 19, t~o tubes 405 14 are fixed to each movable body 403 and extend downwardly (FIG. 18) perpendicularly to the axis of the cylinder unit 16 404. ~ shown in FIG. 19, shafts 407 are inserted in the 17 tubes 405, re~pectively, and normally urged by prings 406 18 in a direation to project out of the tubes 405. The shafts 19 407 have p~ojecting end~ to which a gripper or finger 40B
2~ ls secured by bolts 409. The finger 408 is of a 21 substantially triangular shape as viewed in pl~n as shown 22 in FIG. 20, and ha a presser plate 410 for pre3sing 23 engageme~t with a tire 10 o~ the wheel W, the pres~er plate 24 410 ha~ing a nu~ber of teeth 411 on its out~r surface.
The bolt~ 409 are faatened ~o the shaft~ 407 at 26 eccentric or off-center po~itions as shown in FIGS. 19 and 27 20. The bol~ 407 are ~onnected by a line 11 which extends .

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1 s I 1 617 1 at an angle ranging from 30 to 60 with respect to a 2 tangen~ial line 12 of the tire 10 where it i~ pre-~ed by 3 the pre~er plate 410.
4 A~ shown in FIG. 18, a stack of spaced clutch plates 41~ are atta~hed at one end to each movable body 6 403, and are disposed at the other end in overlapping 7 relati~n to another stack of clutch plates 412 attached to 8 another movable body 403 within a fastening device 413 9 mounted transver~ely centrally on the support plate 401.
The movable bodie~ 403 with their clutch plates 412 held in 11 overlapping relation aq de~cribed above are associated with 12 the cyl~der units 404 having aligned axes. More 13 specifically, the clutch plates 412 of the movable body 403 14 which is moved by the cylinder unit 404a are positioned in overlapplng relation to the clutch plates 412 of the 16 movable body 403 moved by the cylinder unit 404c, whereas 17 the clu~ch plates 412 of the movable body 403 which is 18 moved by the cylinder unit 404b are po~itioned in 19 overlapp'ng relation to the clutch plates 412 o~ the mov~ble body 403 moved by the cylinder unit 404d.
21 ~ach of the fastenins devices 413 i~ operated by 22 a cyllndsr unit 414. When the cylinder unit 414 is not 23 :actuated, the overlapping clutch plates 412 are slidable 24 again~t each other, and the movable bodies 403 are movable alo~g the rails ~02 by the cylinde~ units 404. When the 26 cyllnder unlt 414 iQ actuated to cause the fastening device ~27 413 to pres~ the overlapping clutch plate~ 412 against each ' :

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1 other, thereby ~ecurely fixing the mov~ble bodie~ 403.
2 Thus, after the cylinder units 404 have been operated to 3 cause the f~nger~ 4D8 to hold the tire 10 of the wheel W, 4 the cylinder unit~ 414 are actuated to lock the wheel W on the wheel ~ri~Din~ device 400.
6 ln operation, the cylinder unit 105 ~FTGS. 2 and 7 3~ of each robot 100 i8 operated to lower the unit B of the 8 robot 100 to lthe wheel positioning device 36, and then the 9 cylinder units 404a - 404d are actuated to grip the tire 10 of the wheel W under equal force3 at four point~ on the 11 tire 10.
12 Since the tire 1~ is gripped with equal forces at 13 plural po9itions thereon, the central position o~ the wheel 1~ W remain~ unchanged. In the convetional whe~l gripping deivce, only one cylinder unit is actuated, and its 16 mov2ment i8 tr~nsmitted through a link mechanism to 17 re~pective gripping fingers which grip the wire of a wbeel 18 by depressing the ~ame~to equal depths. H~wever, the tire 19 i not uniform in thickne 8 and have different thickne~ses at localized areas. If the tire area engaged by one finger 21 is thick and the tire area engaged by another finger is Z2 thin, then the thick tire area produces a larger repelling 2 3 ~orce whereas the thin tire area producec a smaller 24 repe}ling force when they pushed to equal depths by the 25 corresponding f ingers . Inasmuch a~ the wheel iS held by 26 the f ingers only t the center of the wheel i9 d;splaced 27 until the repelling force~ from the tire become equalized.

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l A~ a re~ult, the center of the nut runner and the center of2 the wheel are thrown ou~ of alignment, and ~utq cannot b~
3 tlgh~enad. The nut runner and the wheel gripping device 4 cannot therefore be combined with each other.
According to the embodiment of the pre3ent 6 invention, however, the fingers 408 are attached 7 respectively to the cylinder units 404a - 404d so that the fingers 408 are pulled under e~ual forces. Consequently, 9 the tire lO of the wheel W can be gripped such that, even if the tire 10 has different thickneRses, the thick tire 11 area i~ depre5sed to a lesser degree and the thin tire area 12 is depressed to a larger degree. The center o the wire W
13 whiCh ha8 once been positioned i~ thu8 never displaced.
14 The wheel gripping 400 and the nut runner 500 may be combined together in the unit B of the robot lO0 for 16 allowing nut~ to be reliably tightened on the hub bolts.
17 After the wbeel W has been gripped by the wheel 18 gripping device 400 while the wheel center is being kept in 19 positional alignment, the cylinder 105 i9 actuated agaln to l$t the unit B and the ~haft 106 is turned 90 to cause 21 the unit ~ to face the hub 6 while the hub 6 and the wheel 22 W are being kept in central alignment with each other.
23 Then, the cylinder unit 107 is operated to move the wheel 24 gripping device 400 toward the hub 6 until the hub bolt~ 60 2S are iD~erted into the hub bolt insertion holes of the wheel 26 W held by the wheel gripping device 400. ~uts 502 held in 27 re~pective sockets 5Cl of the nut runner S00 ( see ~IG . 17 ) , , :

, :

1 are tightened on the hub bolt~ 60 by rotating the ~ockets 2 501 to complete the attachment of the wheel W to the hub 6.
3 As shown ~n FIG. 17, the nut~ ~02 are tlghtened 4 by rotating the sockets 510 c~unterclockwi~e, for example.
5 When all of the sockets 501 have been rota~ed counter-6 clockwi~e, the nut runner 500 i5 subjected to a orce 7 tending to rotAte the nut runner 500 countercockwise as a 8 whole. The wheel W is then turned bodily by such a force, 9 exerting an undue fo~ce to the hub 6.
To eliminate the above problem, the finger 408 is 11 shaped and the finger 408 is attached to the shafts 407 as 12 follow-~: The line ll interconnecting the bolts 409 and the 13 line 12 tangential to the tire 10 where lt is pressed by 14 the presser pl~te 410 form ~he prescribed angle, as l~ . described above. When the wheel W tends to rotate 16 counterclockwise upon counterclockwise rotation of the 17 sockets 501 iD FIG. 17, the finger 408 is turned in the I8 dire~tion o~ tbe arrow (FIG. 20) about an intermediate l9 point P between the bolts 409 at the time the wheel W i9 ~lightly turned. The teeth 411 of the presser plate 410 21 bite into the tire 10, thereby preventing the wheel W ~rom 22 being further turned. Therefore, no undue force is applied 23 to th~ hub 6 when the nuts 502 are tightened~
24 In the illustrated embodiment, the bolts 40g are eccentrically attached to the respective shafts 407, and 26 the line~ ll, 12 extend at the pres~ribed angle to each ~7 other for enabllng the teeth 411 to bite into the tire lO

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1~1 1677 1 when the nut~ 502 are tightened. The tePth 411 m~y m~re 2 effectively bite lnto ~he ~ire 10 by positioning re~ilient 3 members a~ of rubber b~tween the ~hafts 407 ~nd the fingers 4 408.
~he nut runner 500 will be described in det~il 6 with reference to FIGS. 21 through 23. ~s shown in FI~.
7 21, the nut runner 500 has a main body or hou~ing 503 8 accommodating therein four motors 504 ~only two shown), 9 ~our pairs of bracket~ 50S, 506 ~only two pairY ~hown) moun~ed on a front ~urfa~e (on lefthand side in FIG. 21) of 11 the housing 5~3, and tables 509 coupied by parallel links 12 507, 508 to the brackets 505, 506. To the lin~s 508 closer 13 to the center of the nur runner 500, there are fixed four 14 ~ector ~haped pinions 510, respectively, meshlng with a single rack 511 which i~ operated by a cylinder unit 512 16 positioned between th~ motors 504.
17 Guide rods 513 are moun~ed respectively on the 18 tables 509. Cases 515 are slldably mounted respectively on 19 the gu~de rods S13 with springs 514 disposed around the guide rod~ 513 between the cases S15 and table~ 509.
21 The motors 504 have rotatable output shafts 22 coupled respectively to drive shafts 517 through constant-2:3 velocity univer8al jolnts 516. Other con~tant-velocity 24 u~iversal joints 518 are 8plined to the drive shaft~ 517, 2S respectively, so that the constant-velociSy joints 518 are 26 rotatable with ~he drive ~hafts 517 and axially movable 27 With respect to the drive ~hafts 517. The Con~tant-' :

:

1 -~ 1 1 677 1 velocity joint~ 518 are di~posed in the respective cases 2 515, with the sockets 501 coupled to the distal end~
3 thsreof.
4 Each of the ~ocket~ 501 i~ rot~tably supported in a tubul~r bearing member 519 having a magnet for 6 magnetically attracting a nut ~upplied from an automati~
7 nut feeder. The bearing member 519 i~ ~upported on the 8 case 515 by four leaf ~prings 520 which are located in 9 upper, lower, and lateral position3. The leaf ~prings 520 have di~tal end3 ~upporting th~ rear end of the bearing 11 member 519 to center ~he bearing member 519. The lower 12 leaf ~pring 520 i9 held in overlapping relation to anoher 13 l~af spring 5~1, and attached therewith to the case 515.
14 When the nut runner 500 is moved toward the hub 6, the nut 502 held in the socket 501 abuts against the tip of the hub 16 bolt 60, and the ~ocket 501 is moved inwardly (to the right 17 in FIG. 21). At thl~ time, the socket 501 is relea~ed from 18 the support by the four leaf springo 520. The leaf spring 19 521 ~erve~ to hold the socket 501 from below to prevent the ~ame from tumbling downwasdly.
21 ~ single coil ~pring 523 is disposed around the 22 con~t~nt-v~locity joint 51a between the front end of the 23 ase 51~ and a spring seat 522. A ball bearing 524 is 24 positioned between the ~pring ~eat 522 and an inner ~urface of the soaket 501 for allowing the ~ocket 501 to move under ~26 a very small force ~ub~tantially in the radial direction of 27 the ca~e 515.

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1 For tightening nut~ 502 with the nut runner 500, 2 the nu~s 502 are supplied to the nu~ runner 500, and then 3 the shaft 106 i~ turned 9o from the position of FIGS. 2 4 and 3 until the u~it B faces the hub 6. At thi~ time, the 5 un~t B i~ controlled by the control unit ~ not ~hown ) ~uch 6 that the unit B confronts the hub 6 at the exactly central 7 position thereof which ha~ been computed by the control B un~t based on the output ~ignal~ from the rotary en~oder~
9 312, 313 of the hub bolt phasing devics 300.
Then, the wheel gripping device 400 is moved 11 toward the hub 6 to insert the hub bolts 60 into the 12 respective hub bolt attachment holes 12 of the wheel center 13 11 of the wheel W, and thereaf~er the nut runner 500 is 14 advanced toward the hub 6. The nuts 502 are then tightened over the re~pective hub bolts 70 by energizlng the motors 16 504.
17 The hub bolts 70 may not necessarily extend 18 perpendicularly to ~he attachment surface o the hub 6, but 19 may be inclined at an angle ranging from 2 to 3. For 2a exa~ple, the axi~ 13 of the hub bolt 70 may not be aligned 21 with the axis 14 of the nut 502, as shown in FIG. 23(A).
22 If the nut 502 were tightened in this condition, i~- would 23 not properly be threAded over the hub bolt 60 or would not 24 be removed from the socket 501 after being tightened~over th~ hub bolt 60.
26 To over~ome the above problem, the axi~ 13 of the 27 hub bolt 6~ and the axis I of the nut 502 are brought into 3~

` :-.' ~' ;

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-1 alignment with each other as follows: The ~ocket 501 i~
2 rotated from the po~ition of FIG. 23(A) while the nut 3 runner 500 i~ moved towa~d the hub 6. When the i~ner 4 ~urface of the nut 502 hits the tip en~ of the hub bslt 60 ana the socket 501 is moved ba~k by reactive forces from the hub bolt 60 a~ shown in FIG. 23(B), the ~ocket 501 i~
7 moved substantially radially of the case 515 since the 8 resistance to the rolling movement of the ball bearing 524 9 between the spring seat 522 and the socket ~01 is very small. Thus, the axes 13, 14 are brought into alignment 11 with each other a~ illustrated in FIG. 23~
12 Then, as shown in FIG. 23(C), the nut runner 500 13 is moved toward the hub 6 to move the socket 501 relatively 14 b~ckwards further, whereupon the ~ocket 510 is tilted lS again~t the flexural rigidity of the ~pring 523 to ca~lse 16 the axe~ 13, 14 to be completely aligned with each other.
17 ~or the axes 13, 14 to be ~ompletely aligned with each 18 oth~r, the socket 501 mu~t be moved in any of vertical and 19 later~l directions from the position of FIG. 23~B), and 20 BUCh movement of the socket 501 i8 allowed by the hending 21 of the leaf ~pring 520. The rotation of the motor 504 22 during th~s ime i~ transmitted through the constant-23 velocity joint 516, the dr~ve shaft 517, and the con~tant-24 velocity ~oint 518 to the eocket 501 to tighten the nut S02 2S : over the hub bolt 60.
~26 ~here wheels W are to be attached to an 27 automotive body of a different type with different _o~

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1 3 1 l hl 7 1 di~tances between hub bolt~ 60~ the cylinder unit ~12 in 2 th~ hou~ing 503 are operated to move the rack 511 in one 3 direction or the other. The pinions 510 are turne~ to 4 angularly move the parallel link.~ 507, 508 to move the tables 509 toward or away from each other. Thus, the 6 ~ocket~ 501 supported on the tables 509 by the guide rods 7 513 and the cases 515 are also moved toward or away from 8 each other un~il they are properly aligned with the hub 9 bolt~ 60~
~s des~ribed above, the bearing member 519 of the 11 nut runner 500 i5 floatingly supported o that when the nut 1~ 502 is pressed against the hub bolt 60, the bearing 519 can 13 be varied in po~ition and angle to enable the nut 502 to be 14 allgned with the hub bolt 60 under a ~mall force.
Specifically, the bearing 519 i8 moved first to correct 16 axial misalignment of the nut 502 and the hub bolt 60 and 1~ then to correct angular deviation between the nut 502 and 18 the hub bolt 60. Therefore, the nut 502 will properly b~
19 tightened over the hub bolt 60 without biting threaded engagement, and will ~moothly be removed ~ro~ the socket 21 501 after lt i9 tightened over the hub bolt 60.
22 With the present invention, since the reorienting 23 device for reorienting the hub, the phasing device for 24 phasing the hub bolt~ r and the device for detecting the position of the hub are incorporated in one robot, the 26 ap~aratus i9 integrated and the time required to a~tach 27 wheel~ ~o an au~omotive body is shortened. With the :, "

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131 th77 1 ~rious devic~ combined in one robot, the hub 2 reor~entation, the hUb bolt phasing, and the p~itional 3 detection can be perfo~med without rotating the robot, and4 the wheel atta~hment process can be effected highly efficientlyO
6 The apparatu. can be more integrated and the 7 wheel attachment time can be reduced by incorporating the 8 nut runner and the wheel gripp~ng device in the robot~
9 ~lthough there ha~ been described what is at preqent con~idered to be the preferred embodiment o the 11 present invention, it will be understood that the invention 12 may be embodied ln other specific forms without departing 13 from the spirit or essential characteristics thereof~ The 14 present embodiment is therefore to be con~idered in all a~pects as illustrative, and no,t re3trictive. The scope of 16 the invention i indicated by the appended claims rather 17 than by the foregoing de~cription.

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Claims (8)

1. An automatic wheel attachment apparatus for attaching A wheel to a wheel attachment member of an automotive body, the wheel attachment member having a wheel attachment surface with wheel attachment bolts thereon, said automatic wheel attachment apparatus comprising:
a reorienting device for reorienting a wheel attachment surface of the wheel attachment member;
a phasing device for phasing said wheel attachment bolts, said phasing device being movable longitudinally and vertically of said automotive body to bring said wheel attachment member and the phasing device into central alignment with each other;
a detecting device for detecting the amount and direction of movement of said phasing device;
a nut runner for fastening the wheel to the wheel attachment member while the center of said wheel attachment member as detected by said detecting device is being held in alignment with the center of said wheel; and at least said reorienting device, said phasing device, and said detecting device being combined in a single robot.

2. An automatic wheel attachment apparatus according to claim 1, wherein said reorienting device, said phasing device, and said detecting device are mounted in one portion of said robot, and said nut runner is mounted in another portion of said robot, said portions of the robot being supported on a common shaft, said robot being arranged such that one of said portions confronts said wheel attachment member by rotating said shaft.

3. An automatic wheel attachment apparatus according to claim 1, wherein said phasing device comprises a pair of phasing fingers movable toward each other with said wheel attachment bolts therebetween, and a mechanism for releasing said wheel attachment bolts from dead points of said phasing fingers, said mechanism including a rotatable tube rotatable about the center of said phasing device, and engaging members held by said rotatable tube for engaging said wheel attachment bolts, said engaging members being rotatable with said rotatable tube and movable toward said wheel attachment member at respective speeds selected such that said engaging members traverse the dead points of the phasing fingers while the engaging members are being positioned so closely to said wheel attachment member as to engage said wheel attachment bolts.

4. An automatic wheel attachment apparatus according to claim 1, wherein said nut runner comprises a plurality of sockets for holding nuts to be tightened over said wheel attachment bolts, a plurality of motors for rotating said sockets respectively, a plurality of drive shafts coupled to said motors, respectively, and a plurality of universal joints connecting said sockets and said drive shafts while allowing said sockets to be tilted with respect to said drive shafts, said universal joints being movable axially of said drive shafts to allow said sockets to be retracted under reactive forces produced when the nuts engage said wheel attachment bolts.

5. An automatic wheel attachment apparatus according to claim 4, wherein said nut runner further includes a housing, and a plurality of cases supported on said housing and surrounding intermediate portions of said drive shafts, respectively, said sockets being resiliently biased to move with said universal joints in a direction away from said cases, said sockets being movable radially of said cases, respectively.

6. An automatic wheel attachment apparatus according to claim 1, further including a wheel gripping device cooperating with said nut runner, said wheel gripping device comprising at least three cylinders independently actuatable to produce equal forces, a plurality of fingers coupled respectively to said cylinder units for pressing engagement with an outer tire of said wheel which is pre-positioned, and fixing means for keeping said fingers in pressing engagement with said tire.

7. An automatic wheel attachment apparatus according to claim 6, wherein said reorienting device, said phasing device, and said detecting device are mounted in one portion of said robot, and said nut runner and said wheel gripping device are mounted in another portion of said robot, said portions of the robot being supported on a common shaft, said robot being arranged such that one of said portions confronts said wheel attachment member by rotating said shaft.

8. An automatic wheel attachment apparatus according to claim 6, further including a wheel positioning device cooperating with said wheel gripping device, said wheel positioning device comprising a head vertically movably supported below the wheel which is transferred in horizontal attitude, a rotatable member rotatably disposed in said head, a centralizer disposed in a distal end of said rotatable member and fittable into a central hole of a wheel center of the wheel in response to upward movement of said head, a clamp member for engaging said wheel center while said centralizer is fitted in said central hole, and a pin mounted on said head and engageable in a bolt attachment hole in said wheel center when the bolt attachment hole reaches a prescribed position upon rotation of said wheel by said rotatable member.