Wing Manufacturing

8/3/2019 Wing Manufacturing

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Wing Manufacturing: Next Generation

John HartmannElectroimpact, Inc

Peter Zieve

Electroimpact, Inc

Copyright 1997 Society of Automotive Engineers, Inc.

ABSTRACT

Due to the part size and technological limitations of theavailable assembly equipment, traditional wingmanufacturing has consisted of a three stage process.Parts are first manually tacked together in an assembly

jig, They are then removed from the jig, rotatedhorizontally and craned into an automated fasteningmachine. Finally they are removed from the fasteningmachines and craned to a third station where the manualtacks are removed and the parts are prepped for finalwing box assembly.

With the advent of electromagnetic riveting (EMR) andthe traveling yoke assembly machine this traditionalapproach has been replaced with single stationprocessing. Wing panels and spars can now beautomatically tacked together under continuous clamp upin their assembly jigs using EMR. This eliminates therequirement for disassembly, debur and cleaningrequired with the manual process. While the wing panelsand spars remain rigidly held in their flying configurationby the assembly jig they are fastened with an articulatedyoke. Tool tables are mounted to the bottom of a solidyoke to insure opposing head alignment. Assembly jigsare lined end to end to allow one machine to servicemultiple stations and further enhance productivity.

In addition to efficiency improvements this new processimproves product quality. The elimination of multiplecrane moves and the manual tracking process greatlyreduces the potential in process damage to thecomponents. Since the parts are held rigidly in their

assembly jigs during the entire fastening process, finalpanel and spar definitions are improved. Further, theuse of EMR riveting has been demonstrated to providesuperior fatigue to conventional process.

Two recent case studies of this approach are presented.The E4000 assembly system went into production on theA320 program in early 1998. The E5000 spar assemblysystem, ASAT4, goes into production in mid 1998.These two system are evolutions of earlier systemsintroduced on the Airbus A340 and Boeing 767 programsrespectively. These two systems include a number of

new enhancements over past systems and demonstrateapproaches to both high and low rate aircraft production.

1.0 INTRODUCTION-WING SPARS

The Automated Spar Assembly Tool or ASAT was

originally developed for the Boeing 767 wing spar in thelate 1970s. Since then this powerful concept has beenfurther advanced and integrated into nearly all thecurrent Boeing commercial wing lines. A fourthgeneration system, ASAT4, has been developed for theBoeing C-17 Globemaster III. ASAT4 provides anunprecedented level of flexibility in a minimum amount ofloor space. Similar to ASAT3, ASAT4 consists of avertical traveling yoke machine which straddles the spafixtures. Two fixtures placed end to end form a systemapproximately 220 feet in length which is serviced by asingle machine. This allows manual operations, e.gload and unload, to be performed on one spar while themachine works in the adjacent cell. Each fixture canaccept any of the six C-17 spars. Fixture reconfigurationbetween spars is completely automatic. The single threeaxis yoke machine, the E5000, travels the full systemlength. The yoke is simply supported on the side of arigid gantry structure. The E5000 has completelyredundant tool heads on both legs of the yoke. Thispermits drilling and fastener insertion from either side ofthe spar.

The wings of the Boeing C-17 Globemaster III are builaround three wing spars, front, center and rear. Duringthe initial production years these parts were completelymanually assembled. Twelve different assembly jigs

were used to assemble these six spars. Spar caps andstiffeners are located to the web in the first assembly jig(AJ1) with drill templates used to place fastener holesOnce fastened the spars are then transferred to asecond assembly jig (AJ2) for precision location ocritical components such as the wing rib attachmenfittings. With thousands of fasteners per spar the entireprocess is highly labor intensive.

As part of a program wide effort Boeing engineers werechallenged by the US Air Force to develop long termmanufacturing cost reduction strategies for the C-17


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While automation is recognized as a means tosignificantly reduce labor costs and improve quality, largescale automation projects are typically difficult to justifyon low rate sustaining programs such as the C-17. Anadditional hurdle common with many sustainingprograms was the introduction of automation to anassembly designed without the benefit of Design ForManufacturing and Assembly (DFMA) initiatives. Whilethe C-17 spars are flat in profile, there are offsetfasteners with extremely tight clearances on both sides

of the spar.

To prove cost effective in this environment theautomation system must provide a high degree offlexibility in a minimum amount of floor space. TheASAT4, a fourth generation spar assembly system, wasdeveloped to meet these unique challenges of the C-17program. ASAT4 is based on the concept of in jigassembly with a vertical yoke assembly machine. ThisASAT configuration was initially implemented for theBoeing 737 and 757 programs. ASAT4 however offersan unprecedented level of flexibility along with many newfeatures for improved process speed and control.

2.0 SYSTEM OVERVIEW-ASAT4

ASAT4 consists of a vertical traveling yoke assemblymachine which straddles two CNC controlled flexiblespar fixtures. The fixtures are placed end to end to forma system approximately 220 feet in length serviced by asingle machine. This allows manual operations, e.g.load and unload, to be performed on one spar while themachine works on the adjacent fixture. Each fixture canaccept any of the six C-17 spars. Reconfigurationbetween spars is completely automatic and requiresunder five minutes. The machine is designed withcompletely redundant tool heads which permits drillingand fastener installation from either side of the rigidlysupported spar.

Since ASAT4 was introduced into a sustaining programthe existing AJ1s remain in use for initial location of capto web. This helped to reduce the over system cost andcomplexity. The spars are therefore loaded into thefixtures in a tacked condition. This is illustrated in Figure6. The machine is used to install the bulk of theremaining fasteners. All fastener installation and fixtureoperation are CNC controlled. The high accuracy of theASAT4 machines ultimately will allow elimination of theneed for the AJ2s and reduce overall spar manufacturing

floor space requirements. Components with criticalposition requirements will be located using machinedrilled coordination holes.

3.0 AUTOMATED FASTENING MACHINE - E5000

The requirements being placed on next generationassembly systems demand that the assembly machinebe stiffer, faster and significantly more accurate thanolder systems. These newer machines are actuallybeing designed more as machine tools with theaccompanying performance requirements. The ASAT4

automated fastening machine, the E5000, was designedto meet these challenges.

3.1 MAJOR MACHINE STRUCTURE-E5000

Figure 1: E5000 Machinewith Redundant OperatorStations

The E5000 consists of a rigid yoke mounted to a gantrystructure which straddles the spar fixture and rides onparallel sets of precision beds. The system is completelyCNC controlled with fifteen servo axes all directlyintegrated into a single control, the Fanuc 15MBMASince the C-17 spars are flat no major rotary axes arerequired. The E5000 therefore operates as a three axesmachine for fastener location.

High precision and stiffness is required along the X axisto allow for fast, stable and accurate positioning. The

E5000 is driven in X by four motors in a synchronoustandem configuration, a unique feature provided by theFanuc control. A Rennishaw RG2 tape scale is used fosecondary feedback. This arrangement provides activeelectronic anti-backlash control which does not vary ovetime as is the case with most mechanical anti-backlashmechanisms. Active temperature compensation usingmacro calls within the Fanuc CNC is used to maintainabsolute positional accuracy throughout the largethermal swings present in the Long Beach factoryThese features insure the high accuracy required ovethe 100 foot working envelopes for precise CNC fastenerand detail part location.

Servo positioned tool tables are mounted to the bottomof the yoke legs. See Figure 2. A rigid yoke providesthe most reliable arrangement to maintain alignmenbetween opposing heads. Precision alignment of thetoolpoints is critical to the fastening process especiallyfor the installation of collars onto interference bolts. Theyoke is simply supported on the gantry legs with aminimal constraint design. This insures that in the eventhe machine beds should settle differentially the yoke wilnot see any torsional loading transmitted through thegantry which could cause the toolpoint to move out o


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alignment. These features provide the optimalconfiguration for long term process reliability.

The yoke is positioned vertically by one Y-axis motorwhich drives Y carriages on either yoke leg through apair of right angle gear boxes. Secondary feedback forthe Y axis is provided with a Heidenhain glass scalelinear encoder which guarantees high precision over the72 inch vertical working envelope. The entire Y-axis iscounterbalanced with a 300 psi pneumatic

counterbalance system. Air was chosen over more amore conventional nitrogen charged hydraulic systemsince pneumatic systems are less costly and more easilymaintained. Functionally the pneumatic system hasproven equal in performance to the older hydraulicsystems.

3.2 PROCESS HEADS-E5000

While the C-17 spars are flat in profile, there are offsetfasteners with extremely tight clearances on both sidesof the spar. The E5000 was therefore designed withcompletely redundant tool heads mounted on both legs

of the yoke. This permits drilling and fastener insertionfrom either side of the spar. The spar remains fixedthroughout the assembly process. Redundant operatorstations allow the operator to monitor the process fromthe most appropriate side with no loss of control. Theseare illustrated in Figure 1.

Two CNC controlled clamp tables are mounted to bottomof the yoke legs. Clamp up on a rigidly held part withoutpart movement is critical to the success of the in jigassembly process. Clamping is accomplished withoutimparting a differential load to the spar by driving onetable forward and actively sensing the spar surface with

a non contact panel probe. The opposing table thendrives into the part under load cell feedback to completethe clamping cycle. Clamping is maintained throughoutthe installation process by continual closing of the clamptable servoloops around the loadcell. This enablingoperation is described in detail in Hartmann [1].

The fastener installation tools are mounted to redundantshuttle tables which ride on the underside of the clamptables. See Figure 2. The tools consist of a servo drivenspindle, a feedernose servo EMR, a smart pneumaticbolt inserter, a hole probe, a fastener ejection tool and aresynchonization camera. The shuttle table axis is themost critical axis to cycle rate. For each one inch

machine move between fasteners the tool shuttle tablemust move approximately three feet between the varioustools. Linear motors drive the shuttle tables with 1Gacceleration to a maximum velocity of over 40 in/s. Theintegration of the linear motor shuttle table alone hasreduced process cycle times by 15%-20%.

Figure 2: Clamp Table with Process Tools

A number of features have been integrated into theprocess tools to enhanced the speed and verification ofthe fastening process. These include:

1. The 15,000 RPM DC servo controlled spindle isprovided with water cooling for increased heatdissipation required at higher power levels, The

spindle is configured with an Ott Jacob powereddrawbar which allows for quick change of theappropriate cutters. Cutters can be preset withtheir set up parameters stored in the CNC toreduce downtime during tool changes.

2. Past electromagnetic riveting heads (EMR) havebeen positioned using air cylinders. Onedisadvantage of this method is that sincematerial stacks vary infinitely and slug rivets onlycome in 1/16 increments it is difficult to properlyset the rivet protrusion height. Servo control othe EMR forming dies axial position by the CNChowever permits precise balancing of the slug

rivet protrusion on both sides of the spar. Thedesired protrusion is calculated by the CNCusing the stack thickness and selected rivet gripThe EMR is then servoed to the calculatedposition for exact protrusion balancing. Thisfeature provides more repeatable and higherquality fastener installation results.

3. The axial position of the pneumatic bolt inserteis controlled by an air cylinder which has a lineaencoder grating etched directly on its rod. Thispowerful feature allows continual monitoring andverification of the bolt insertion process. Bollength, orientation, diameter, installation speedand bolt/hole interference levels all can bechecked real time with this feedback device.

4. A servo driven hole probe based on precisionball gages is used to validate hole diameter inprocess and prior to fastener installation. Holediameter is one parameter which cannot bemeasured after the fastener installation cycle iscompleted. A record of the hole diameter iscritical to the long term goal of reduction oelimination of test coupons.

5. A fastener ejection tool allows automaticrecovery in the event that a bad fastener is


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detected prior to forming. This tool increasesthe efficiency and safety of the system as iteliminates the need for operator intervention toclear unwanted fasteners.

6. The resynchronization camera is used toreference the machine to the appropriate fixture.In additional it is used to verify the location ofparts which were manually installed in the initialtacking stage. This tool thereby allows theE5000 to function as a very large CMM forverification of part and fastener locations.

The requirement to fasten six different spars with onemachine is by itself not a significant challenge in todaysDFMA design environment. The C-17 however was notdesigned with this philosophy and therefore access tothe fasteners varies considerably across the differentspars and even with a single spar. The E5000 system isdesigned to install two diameters of slug rivets as well asthree diameters and two types of interference bolts.There are a assortment of different clearancerequirements for each fastener size and type. To meetthese requirements a variety of front end or clampnose

configurations were developed. One offset configurationis illustrated in Figure 3. To avoid collisions and potentialdamage to the spars it is imperative that the correctclampnose is installed for the appropriate part program.Each nosepiece assembly has therefore been providedwith an identification tag realized through a series of dipswitches and a D shell connector. This connector and allother utility connections are fully integrated into theheadstone and the appropriate nosepiece for quickchange convenience. This greatly simplifies the toolchange process for the operators.

Figure 3: Offset Clampnose

The large number of fasteners which must be supportedrequires a compact fastener feed system. Fasteners arestored in coiled tube cartridges which are approximatelythe size of a small briefcase. Each cartridge holdsaround five hundred fasteners. The narrow cartridgecross section permits a large number of cartridges to becarried on the gantry in a relatively small area. The sixty

point system easily fits onto one side of the gantry(Figure 4), The individual escapements arepneumatically controlled through a PLC which resides onthe Fanuc fiber optic ring. The cartridges are multiplexedthrough a series of laterals located below the mainstorage racks. A second routing station located on top othe gantry directs the requested fastener to theappropriate side of the machine. For low fastener countsdrops tubes are provided at the operator stationsupstream of the main fastener feed station to permit

manually feeding. The cartridges are automaticallyloaded off line with vibratory bowl feeders. This removesall inherent problems of dealing with bulk fasteners offline and away from the production environment. For afurther discussion of these feed systems see, Rink [2].

Figure 4: Fastener Feed System


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4.0 FLEXIBLE FIXTURES-ASAT4

Jigs are typically used in the aircraft industry to providefaster, simpler and more repeatable location of detailparts than could be accomplished by repeated manuallayouts. In the past large component jigs have beendesigned for high rigidity and precision to meet the tighttolerances required for integration with other aircraftcomponents in final assembly. Drill blankets are used tolocate holes and locating jigs index subcomponentsrelative to the nearest available reference. Over the firstfew shipsets jigs are typically modified to correctunforeseen problems encountered in the downstreamassembly process.

The result is typically the development of dedicatedinflexible fixtures for each major aircraft component. Forlower rate programs this inflexibility can prove costly.The large number of jigs are expensive to maintain androutine. Floor space requirements are high and cannotbe as easily amortized over low production rates. Thelack of jig flexibility can also hamper the design ofderivative aircraft modifications. With conventional jigs

changeover time between variants can significantlyreduce efficiency and drive up costs. Assembly jigflexibility is therefore key to the commercial success oflow rate programs.

The ASAT4 system contains two flexible fixtures whichare situated end to end to form one automated cell. Thetwo fixtures are identical and each can accept any of thesix C-17 wing spars. Since the C-17 is a relatively lowrate program the decision was made to keep the originaldedicated AJ1s for use as tack fixtures only. Unlikeprevious ASATs the spar is therefore provided to theASAT4 cell in the tacked configuration. ASAT4 is thenutilized to install the bulk of the fasteners and toultimately locate and install critical components such asthe rib attachments. This revised job description alloweda significant reduction in the number of indices requiredrelative to previous ASATs and thereby reduced theoverall system cost. Despite the reduced number ofindices the fixtures still must maintain the spars inprecise and repeatable locations relative to the machinecoordinate system since all fastening is performed undercomplete CNC control.

Figure 5: Flexible Fixture Unloaded

Figure 6: Loading Spar into Fixture

Figure 7: Spar Loaded in Fixture


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Each fixture consists of sixteen upper index assemblies,sixteen lower index assemblies and one primary indexassembly. These assemblies are mounted to a series ofrigid steel based modules which are placed between thetwo X-axis machine beds. The sixteen lower indexassemblies provide the anchor for the spar fixture andare used to clock the spars X-axis parallel to that of themachine. Each lower index consists of three uniqueindex nests which correspond to the cap geometry of thefront, center and rear spars at that particular station

value. The nests are spaced 120 degrees apart on apneumatic rotary indexer as shown in Figure 8. Theindexer operates using a Geneva mechanism whichprovides .001 in. true position repeatability.Pneumatically controlled toggle clamps retain the spar inthe lower nests. The clamps move on a vertical slideand index off each individual nest to insure properorientation of the clamp body to the respective spar capas the spar heights vary between the three spars.Belleville washer stacks provide the clamp arms withsufficient compliance to accommodate the gage changesbetween the three spars at each station.

The entire lower index assembly is mounted to the fixturebase modules though a second pneumatically controlledrotary indexer. This second indexer provides 180degrees of motion. By placing the center of the indexersrotation coincident with the spar datum plane the sameassembly is able to locate an opposite hand spar byreversing the orientation of the nest. The second indexerand all required utilities are mounted in a covered trench.

Figure 8: Lower Index Assembly

The upper index assemblies hold the spar vertical bygrabbing onto the upper spar cap and thereby maintainthe spar plane perpendicular to the machine drill axis.These components are mounted to vertical posts whichare provided with sufficient vertical motion to sink into thefloor and completely out of the machine path.Servomotors are used to position the upper index bothvertically and horizontally under CNC control. Upper

index positions are therefore all programmed positionswhich are easily changed in software. A swing clampwith ample compliance to accommodate the different capwidths draws the upper cap into the index.

Figure 9: Upper Index Assembly with Post Fully Down

The spars are indexed in the X-axis through a singletooling hole in the web designated as the primary indexThe primary index is shown in Figure 10. The toolingholes in the spars webs have been placed such that asingle index location can be used for all six spars. TheAJ bases sit on conventional jig feet and are fixated tothe foundation in X at one point which coincides with theprimary index. This insures that all growth due totemperature for both the fixture and the spar originatefrom the same point. A single primary index provides afixed origin point to which the machine can synchronizeThis is important to insure proper functioning of themachine temperature compensation which is critical toprovide the accuracy required for precision jigless

component location.

Figure 10: Primary Index with First Lower IndexAssembly

The two flexible fixtures are completely automated foboth their set up and operation. The fixtures are directlycontrolled by GE PLCs which reside on the fiber opticring of main system brain, the Fanuc 15MBMA CNC


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Each fixture has thirty two servo motors in addition topneumatically controlled actuators. Changeoverbetween one spar configuration to another requiresunder five minutes and is controlled either from themachine button panel or remotely from the fixture junction boxes. No manual intervention is required.Once running under part program control all operation ofthe fixture is controlled through M-codes for completeCNC operation.

5.0 INTRODUCTION: WING PANELS-E4000

The first application of the E4000 yoke assemblymachine cell is on the A319/A320/A321 upper wingpanels. The machine has built a pair of A320 upper wingpanels. A second set is nearly completed as of thiswriting.

In the E4000 assembly cell detailed parts are loaded intothe cell. These detailed parts include seventeenstringers, two skins, a buttstrap and a pylonreinforcement. These parts load into the clampingdetails of the wing panel holding fixtures, both port and

starboard. The E4000 machine then runs across thefixtures, drills critical holes and installs all of thepermanent fasteners. When the wing panel is removedfrom the fixture all of the assembly work is complete.

6.0 E4000 FACILITY

a. The machines and fixtures sit on a dedicatedfoundation provided by BAe. The foundation is sixty-sixmeters long with features for mounting the machine railsand the two fixtures (port and starboard).

b. The facility includes two upper wing panel fixtures, a

port and a starboard.

c. There are two parallel sixty meters runs of levelableprecision bedrail, fifty-six meters of continuous RenishawRG2 scale on each bed, IKO precision recirculating rollerbearing and ground rack. The bedrails straddle and runalong both sides of the fixtures.

d. The E4000 riveting machine runs on the bedrail.

e. There are floor plates surrounding the machine andfixture.

f. There is an offline fastener feed system.

7.0 E4000 ASSEMBLY MACHINE KINEMATICS

The E4000 machine is designed to access the entiresurface of the wing panel for drilling holes and installingrivets and lockbolts. Each wing panel is fifteen meterslong and three meters in width. The width of the panel isthe vertical height that the machine must traverse sincethe panel is placed vertically in the fixture.

The E4000 machine is capable of accurate positioning ofthe toolpoint. On the E4000 machine the toolpoint is thepoint where the drill first touches when entering the skinThe E4000 is designed to locate this point within .008over the work envelope of the machine.

The E4000 machine utilizes a solid yoke that isarticulated in five axes. By rotating the solid yoke thealignment between the opposing heads is maintainedCorrespondingly, the work axis of the yoke is horizontalThe E4000 machine can rotate the yoke +/-15 degrees inA and B to keep the drilling axis normal to the wing panesurface. Rotation of a solid yoke provides precisionalignment between the opposite heads. Alignment within.007 is required for reliable collar loading, and it isachieved. The yoke is employed as the engine oalignment and clampup.

The yoke is connected by two trunnions that attach neato the extreme points of the yoke. By attaching thetrunnions near to the extreme points the stability of theyoke is enhanced. Each trunnion features twoperpendicular passive rotary axes. One of the rotary

axes is for the A axis, the second is for the B axis. Thetrunnions are supported by the gantry. In addition thetrunnion on the stringer side features a passive lengthchange slide.

The gantry has two independent X axes, one on eachside of the wing panel. In addition, the gantry featurestwo separate Y saddles that also straddle the wing panelWhen the two gantry X axes move in unison the yoketranslates in X. When the two gantry X axes movedifferentially the yoke rotates in B.

The motion is similar for the two Y axes. Parallel motion

causes a Y translation of the yoke. Differential motioncauses the yoke to rotate in A. A figure is enclosedwhich illustrates the resulting kinematics.

The servo axes of the E4000 machine are as follows:

AXIS SIDE DESCRIPTION FEEDBACK

Xm skin gantry racktandem master

RG2

Xs skin gantry racktandem slave

tandem

Im stringer gantry racktandem master

RG2

Is stringer gantry racktandem slave

tandem

Ym skin vertical ballscrewmaster

Heidenhein

Ys skin vertical ballscrewslave

Heidenhein

Jm stringer vertical ballscrewmaster

Heidenhein

Js stringer vertical ballscrewslave

Heidenhein

U skin head in/out for2000 lbs of

Heidenhein andload cell


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clampup

V stringer head in/out for2000 lbs ofclampup

Heidenhein andload cell

C stringer anvil rotation motor encoder

K1 skin EMR in/out motor encoder

K2 skin hole probe in/out motor encoder

E skin shuttle tablelinear motor,

2m/sec transferspeed

Heidenhein

W1 skin spindle #1 feed Heidenhein

W2 skin spindle #2 feed Heidenhein

In addition to the above listed real axes, the E4000 alsofeatures three virtual axes. These axes respond tomotion commands and are displayed on the CNC but areactually the result of calculation.

Table 2: E4000 machine virtual axes

A yoke A rotation, ARCTAN[(Y-J)/192"]B yoke B rotation, ARCTAN[(X-I)/192"]

Z Z plane of workpoint from yoke center

Table 3: E4000 spindle drives

S1 spindle 1, 13,500 RPM, HSK 50 hydrauliccollet with Ott-Jacobs power drawbar

S2 spindle 2, 13,500 RPM, HSK 50 hydrauliccollet with Ott-Jacobs power drawbar

As already mentioned, the X axis is 55 meters long. TheY axis is 3.55 meters, although some of this height issacrificed to allow for A axis rotation.

8.0 WING PANEL HOLDING FIXTURES- E4000

Elements of the fixtures include:

a. Fixture bases which can be precision leveled

b. Upper beam on each fixture

c. 14 rotating headers on each fixture

d. Stringer clamps and buttstrap grippers are mountedon the headers

e. Slider for the inboard end

f. Stringer inboard locators are mounted on the slider

g. Slider moves out of the way to permit unloading

h. Skin straps to pull in panels, air motors pull in straps

The fixture is designed so that every location on thepanel can be accessed. This is achieved by the rotatingheaders. As illustrated the stringer side head is 14wide. The dimension to the inside surface of the rotatingheader is eight inches. Therefore, coming from eithedirection the stringer side head can rivet up to thecenterline of each rotating header.

9.0 PROCESS TOOLS - E4000

As shown in the attached photo the shuttle table on theskin side carries seven tools. All of the tools on the skinside remain permanently attached with the shuttle tablewhich uses a high speed linear motor to transfer fromtool to tool. The shuttle table positions on the skin sideare as follows:

a. EMR

b. bolt inserter

c. sealant applicator

d. spindle 1

e. spindle 2

f. hole probe

g. resynch camera

The stringer side has multiple anvil setups. The anvisetups have side tooling to perform the necessaryfunctions. Stringer side tooling is shown in the photoThe various stringer side tools are listed in Table 4. Thestringer side anvils attach to a spring loaded crash base

which freezes machine motion if the anvils are deflectedto the side or outward.

Table 4 E4000 stringer side tooling

ANVIL FUNCTIONS SIDE TOOLING

drill only drill only V tracer

shallow offset rivets, 5/16collars

Y/V tracer, double hit,collar feed

deep offset 1/4 collars Y/V tracer, collar feed

straight 1/4 and 5/16collars

Y/V tracer, collar feed

The sequence for installing a rivet is as follows:

a. clampup

b. drill and countersink

c. feed, measure rivet and upset rivet with EMR

d. double hit if required


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e. shave

The sequence for installing a lockbolt is as follows:

a. clampup

b. drill and countersink

c. probe hole

d. apply sealant to hole

e. feed and measure bolt

f. feed collar

g. drive bolt

h. swage collar with EMR

10 MANUFACTURING PROCESS - E4000

a. Stringers, buttstrap and pylon reinforcing are loadedinto the clamps. All rotating supports are initially closed.

b. Sealant is applied at the rib bays and at the stringerends.

c. Two skins are loaded in. The lower skin sits on thetrailing edge locators and is pushed in by removablepushers. The upper skin is attached to lugs and is slid inand the gap then adjusted. Skin straps press the skinsup against the stringers.

d. The E4000 machine runs over the panel and installsrivets and lockbolts to stabilize and hold firm all of the

sealed areas. This includes fastening of the buttstrap.

e. Precision 5 axis drilling is performed on the inboardend. Only the U side head is engaged for the inboard

hole drilling. The U side head presses the panel upagainst the fixture. The inboard pattern is employedwhen the wing panel is attached to the center wing box.

f. After the seal pass is complete the skin straps areremoved and the production pass begins. Headers arerotated out of position to create 48 wide bays. The bulkof the rivets and lockbolts are installed.

Some of the fastener locations utilize sensors (there aresix sensors, four skin side normality sensors and a twoaxis stringer side tracer). Some are located under CNCcontrol.

CONCLUSION

The ASAT4 system has been designed to meet thespecified requirements of low rate productionrequirements of the Boeing C-17. A high degree oflexibility has been integrated into the spar fixtures andthe E5000 automated assembly machine to allow onesystem to meet the production requirements for all six C-17 wing spars.

The E4000 Wing Riveting System has provided BritishAerospace with a flexible automated assembly methodwhich assists in meeting ramped-up Airbus productionschedules. Its centerpiece, the five axis solid yoke withworkheads on each end of the yoke, accurately andeffectively installs both rivets and lockbolts over theentire wing panel surface including offset areas.

Both these systems represent the transition to the nextgeneration of the automated wing assemblly processwhich involves in jig riveting. The in jig process savesfloor space and improves control of the build process

ACKNOWLEDGMENTS

The authors wish to thank the ASAT4 team both withinElectroimpact and Boeing for all the hard work that madethis project a success. The authors also would like toacknowledge the assistance of British Aerospace Airbus in providing material for this paper.

REFERENCES

1. Hartmann, John et.al., A Flexible Automated AircrafAssembly System, Phase 1:Process Development, SAEAerofast Proceedings, 1996.

2. Rink, Phil et. Al. ,Next Generation Fastener FeedSystems, SAE Aerofast Proceedings, 1995.


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Figure 1: Overall view of cell

Figure 2: Stringer side workhead andshuttle table

Figure 4: View of completed panel

Figure 5: stringer side view

Figure 6: skin side workhead

Figure 7: stringer side anvils

Figure 8: E4000 installs offset fasteners

Figure 3: Operator Platform


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Figure 8: Skin side panel in fixture at root

Figure 9: Cartridgefastener feed system


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Figure 10: E4000 Machine Kinematics


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Figure 11: offset anvil


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Figure 12: E4000 Machine View

Figure 13: String side head clears the rotating support.Rotating supports provide a 48 wide workbay.


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Figure 14: Offset anvil

Figure 15: E4000 machine view

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