WO1999012698A2

WO1999012698A2 - Improvements relating to airframe manufacturing

Info

Publication number: WO1999012698A2
Application number: PCT/GB1998/002734
Authority: WO
Inventors: Ghassan Matar; Colin Alfred Hawes
Original assignee: Geodetic Technology International Holdings N.V.
Priority date: 1997-09-10
Filing date: 1998-09-10
Publication date: 1999-03-18
Also published as: GB9719281D0; WO1999012698A3; WO1999012698A8; GB2329138A

Abstract

A machine for cutting openings in an airframe section comprises a gantry (1) which is translatable past an blank (6), open which cutting machines (4) are mounted, each cutting machine (4) comprising a platform (8) supported from the gantry by three pairs of legs (9) which are coupled to the platform by three universal joints, each pair of legs coupling together at a respective one of the universal joints, and at their other ends are coupling to spaced-apart locations of a mounting (10) in the gantry by means of leg-drive motors (11) which are mounted in universal joints. The motors enable the leg lengths to be adjusted independently so that the position and orientation of the platform can be precisely determined. A cutting head (12) is mounted on the other side of the platform and the entire machine is precision controlled by a computer system (3) which controls all aspects of the cutting machines (4) and the position of the gantry.

Description

IMPROVEMENTS RELATING TO AIRFRAME MANUFACTURING

Field of the Invention:

This invention concerns improvements relating to airframe manufacturing, that is to say the manufacture of aircraft fuselages, wings, tailplanes and the like.

Background of the Invention:

Airframes have conventionally been manufactured by a process involving the construction of an open framework which is subsequently panelled over by the rivetting of structural panels to the framework, and it can readily be appreciated that this is a time consuming and labour intensive operation.

Recently, proposals have been made to construct aircraft fuselages and the like from lightweight, high strength composite materials such as carbon fibre composites. A "blank" for a fuselage, for example, can be assembled on a former by deposition of the composite onto the former, allowing the composite to cure and then removing the former. The former can be inflatable and deflatable to facilitate its use and, more particularly, facilitate its removal from the formed blank. Once the composite has cured, access openings such as doors, windows etc. can then be cut into the formed blank.

The abovementioned proposal to use composite blanks in the manufacture of airframe sections has attractive advantages over the traditional manufacturing method, but nonetheless gives rise to problems as regards the cutting of access openings since these must be cut with precision and without unduly stressing the airframe blank in the region that has to be cut. The present invention addresses this problem.

Summary of the Invention:

In its broadest aspect, the present invention proposes to make use of one or more machines according to the teachings of WO-A-92/17313 to cut the access openings in the composite airframe blank.

We have pioneered the development of machines based upon the mechanical manipulator that is described in WO-A-92/17313 and which comprises a platform suspended by means of three pairs of supportive legs which are coupled thereto at triangularly spaced-apart locations by means of three universal joints each of which couples to one end of each of the two legs of a respective pair, the two legs of each pair extending from their respective universal joint in divergent directions to spaced-apart locations in an overhead mounting (which is preferably domed as described in International Patent Application No. PCT/GB97/01562 ) whereat each leg is drivingly engaged by a respective leg-drive motor arranged to move the leg in its own longitudinal direction whilst simultaneously accommodating the angular leg movement that results, the motors being gimbal-mounted or, more preferably, being mounted within spherical bearings- for accommodating angular or pivotal movements of the legs. The platform position and orientation can be controlled by appropriate operation of the six leg drive motors and provides for the mounting thereon of a variety of working tools including mechanical cutters and drills for example, lasers, high-pressure fluid cutters, robotic components etc. Disclosed in WO-A-92/17313 for example is an arrangement wherein the platform has a rotary stage mounted thereon, a pivotal stage is mounted on the rotary stage and a spindle motor is mounted in the pivotal stage for driving a rotary cutter.

The system of WO-A-92/17313 further incorporates a computer control system which determines the operation of the various motor drives and other components of the system whereby the platform and a working tool carried by the platform can be manipulated with a precision which exceeds the standard levels of precision achieved by conventional X,Y,Z orthogonal axis machine tools. Shaft encoders and other feedback measurement systems are provided which enable the computer control system to operate with high precision.

Described hereinafter is an exemplary system for forming access openings in a composite material airframe blank which comprises a mounting for the airframe blank, a gantry extending on opposite sides of the mounting and over the top thereof, and a plurality of machines constructed according to the teachings of WO-A-92/17313 mounted in said gantry so as to be capable of working on an airframe blank in said mounting, said gantry being movable in translation to enable the machines to work at different positions along the length of the airframe. In use of such a system, the machines (hereinafter called hexapod machines) can first be arranged to measure the airframe blank on a first pass of the gantry along the length of the airframe, there being suitable probes provided on the machine platforms to enable such measurements to be made, and can then be arranged to cut the required openings in the measured blank at precisely determined positions, the measuring of the blank and the cutting of the openings being effected under precision control by the computer systems of the machines.

The above and further features of the present invention are set forth in the appended claims and will be described hereinafter by way of example with reference to the accompanying drawings.

Description of the Drawings:

Figure 1 is a perspective view of an airframe manufacturing system embodying the present invention; Figure 2 is a side elevation view of the system of Figure 1;

Figure 3 is a front elevation view showing an airframe blank mounted within the system of Figure 1 and with the gantry of the system around the airframe; and

Figure 4 is a front elevation view of the system of Figure 1 which illustrates a toolchanger facility included in the system.

Detailed Description of the Embodiment: Referring to Figure 1 of the accompanying drawings, a manufacturing system is shown in which a gantry 1 is movable along a rectilinear track 2 under control from a computer system 3. The gantry 1 has three hexapod machines 4 mounted therein, one on each side of the track 2 and the other above the track 2. A mounting 5 is provided between the two rails of the track 2 for supporting a composite airframe blank 6 as shown. A toolchanger facility 7 is provided at the front end of the system as shown.

Each of the hexapod machines 4 is substantially as described in WO-A-92/17313 aforementioned. As mentioned hereinbefore, the machines 4 each comprise a triangular platform 8 having a pair of support legs 9 connected to each apex of the platform by a ball-and-socket universal joint mechanism as described in WO-A-92/17313. The six legs 9 attached to each platform 8 extend in divergent directions to locations in a bulkhead 10, preferably a domed bulkhead as described in our International Patent Application No. PCT/GB97/01562 , whereat the legs 9 each engage respective leg drive motors 11 mounted by means of universal joint arrangements such as to accommodate pivotal movement of the legs 9 without permitting rotation thereof about their axes. As is described in WO-A-92/17313, the leg drive motors 11 enable the legs 9 to be moved so as to vary the distance between their coupling to the platform 8 and their coupling to the bulkhead 10, under computer control, so as to adjust the position and orientation of the platform 8 within the working volume of the machine. A work head 12 may be attached to the opposite side of the platform 8 from the support legs 9 and different kinds of work heads may be provided for accomplishing different tasks. In the arrangements illustrated in the accompanying drawings, the work head 12 is as described in WO-A-92/17313 and comprises a first stage providing precision positioning within a rotational plane parallel to the platform 8, a second stage mounted on the first stage and providing precision positioning within a pivotal plane orthogonal to the plane of movement of the first stage, and a rotary drive for a cutting tool mounted on the second stage.

In operation of the illustrated system, access openings may be cut as desired in the airframe blank 6 by appropriate operation of the hexapod machines 4 as the gantry 1 is translated along the track 2, the work heads of the machines 4 incorporating appropriate cutting tools for different purposes and, as shown in Figure 4, the arrangement may be such that each hexapod machine can directly access a range of cutting tools held in the facility 7 and can effect tool changing automatically under computer control. As previously mentioned herein, the hexapod machines can be utilized to measure the airframe blank, for example to determine its precise orientation on the mountings 5, and suitable measurement probes may be provided in the facility 7.

The illustrated arrangement is exemplary only and modifications and variations thereto are possible without departure from the spirit and scope of the present invention as set forth in the appended claims. For example, the mountings 5 could be arranged to enable the airframe blank 6 to be rotated about its axis to enable access openings to be cut in its underside. Alternatively, or additionally, the gantry 1 could be such as to enable the hexapod machines 4 to be rotated bodily about the airframe blank 6. The arrangement illustrated in the accompanying drawings could also be used in applications other than for cutting access openings in composite airframe structures.

Claims

CLAIMS :

1. A manufacturing system wherein a plurality of machines are mounted on a gantry so as to be capable of operating upon a workpiece straddled by the gantry, each said machine comprising a means defining a base for further movement which is mounted for movement with substantial freedom in translation and rotation relative to said gantry by means of a plurality of legs the effective length and angular orientation whereof are controllably adjustable, and wherein tne gantry is itself movable for enabling said machines to operate upon an elongate workpiece.

2. A system as claimed in claim 1 wherein the means defining a base for further movement of each said machine comprises a platform and three pairs of supportive legs are coupled thereto at triangularly spaced-apart locations by means of three universal joints each of which couples to one end of each of the two legs of a respective pair, and the two legs of each pair extend from their respective universal joint in divergent directions to spaced-apart locations in a mounting in said gantry whereat each leg is drivingly engaged by controllable leg drive means for moving the leg in its own longitudinal direction, the leg drive means associated with each leg being mounted so as to be capable of accommodating angular movement of its respective leg.

3. A system as claimed in claim 2 wherein the triangularly spaced-apart locations whereat the three pairs of supportive legs couple to the platform are equilaterally spaced apart, and the locations in the mounting whereat the legs are drivingly engaged by the leg drive means are arranged in a hexagon wherein the spacing between the respective locations for the two legs of each pair of legs are uniform as between the three pairs of legs, and the spacings between the adjacent legs of different pairs of legs are uniform.

4. A system as claimed in claim 2 or 3 wherein the leg drive means comprise motors drivingly engaged with the legs, for example electric motors driving the legs by means of recirculating ball screw couplings with the legs.

5. A system as claimed in claim 2 or 3 or 4 wherein the leg drive means are mounted in the mounting by universal joint means.

6. A system as claimed in claim 5 wherein said universal joint means mounting the leg drive means comprise ball and socket means.

7. A system as claimed in claim 6 wherein said ball and socket means mounting the leg drive means comprises a spherical ball within which is housed the leg drive means.

8. A system as claimed in any of claims 2 to 7 wherein the universal joints coupling the ends of respective pairs of the legs to the platform comprise ball and socket means.

9. A system as claimed in any of claims 2 to 8 including means coupled to said platform and providing for movement additional to the platform movement arising out of movements of the legs.

10. A system as claimed in claim 9 wherein said means for providing said additional movement is adapted and arranged to provide rotational movement in a plane parallel to a plane defined by the platform.

11. A system as claimed in claim 10 wherein said means for providing rotational movement in a plane parallel to a plane defined by the platform comprises a motor driven member rotatably mounted with respect to the platform.

12. A system as claimed in any of claims 9 to 11 including yet further means coupled to said additional movement providing means and providing for a different degree of movement to that provided by said additional movement providing means.

13. A system as claimed in claim 12 wherein said yet further movement providing means is arranged to provide rotational movement in a plane generally transverse to the plane defined by the platform.

14. A system as claimed in claim 13 wherein said yet further movement providing means comprises a motor driven pivotal arrangement.

15. A system as claimed in claim 14 wherein said pivotal arrangement comprises a motor adapted to provide rotational movement about an axis transverse to the pivot axis.

16. A system as claimed in claim 15 wherein a tool-holder is arranged to be rotated by said motor.

17. A system as claimed in any of the preceding claims in combination with a computer system controlling the operation of the system.

18. A manufacturing system substantially as herein described with reference to the accompanying drawings.

19. The use of a manufacturing system as claimed in any of the preceding claims in the manufacture of an airframe section.