AU620035B2 - Plate working machine - Google Patents

Description

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AU-AI-17282/88 WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau 0 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 88/ 09236 B23B 39/14, 47/00, B23Q 3/06 Al B23B 3/146 A (43) International Publication Date: 1 December 198 (01.12.88) (21) Internatir,"; Application Number: PCT/AU88/00149 (81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (Euro- (22) International Filing Date: 17 May 1.988 (17.05.88) pean patent), FR (European patent), GB (European patent), IT (European patent), JP, KR, LU (European patent), NL (European patent), SE (European pa- (31) Priority Application Number: PI 2016 tent), US.

(32) Priority Date: 18 May 1987 (18.05.87) Published (33) Priority Country: AU With international search report.

(71) Applicant (for all designated States except US): FAR- LEY MANUFACTURING PTY. LTD. [AU/AU]; 7-9 Walter Street, Glenroy, VIC 3046 (AU).

(72) Inventor; and A. OJ.P. 2 FEB 1989 Inventor/Applicant (for US only) FARLEY, Peter, Anthony [AU/AU]; 24 Hodgson Street, Heidelberg, VIC 3084

AUSTRALIAN

(74) Agent: SANDERCOCK, SMITH BEADLE; 207 2 1 DEC 1988 Riversdale Road, Hawthorn, VIC 3122 (AU).

PATENT OFFICE (54) Title: PLATE WORKING MACHINE (57) Abstract A plate working machine comprising a metal plate supporting table a pair of rails 3) extending along the sides of the table a driven support means for travel along the rails said support means comprising a spaced pair of support beams 6) extending from one rail to the other and joined at either end by cross members A drilling assembly is mounted on tracks (10, 11) mounted on the beams 6) and a plasma profiling head (12) is carried by the drilling assembly and extends over the beam and downwardly towards a position adjacent the table i I LI ii -LL IY n: WO 88/09236 PCT/AU88/00149 1 1 TITLE: PLATE WORKING MACHINE 2 Field of the Invention: 3 This invention relates to improvements in metal plate 4 working machines and more particularly to a machine capable of performing cutting and drilling operations over a single 6 plate supporting structure.

7 Background of the Invention: 8 Most metal plate working involves both cutting by means 9 of a guillotine or by means of an oxy-fuel type profile cutter, and subsequent drilling, tapping or counterboring.

11 Many plate working operations also require line marking for 12 subsequent bending and welding operations.

13 At the present time, the above functions are performed 14 by means of separate and distinct machines and accordingly the metal plate being worked must be transported from one 16 machine to another. Thus, much of the labour expended in 17 working metal plates is consumed in transporting the plate 18 in the workshop. Where a plate is very large and heavy, the 19 moving operation may occupy a considerable amount of time and involve expensive transporting equipment. Thus, it is 21 not surprising that studies have shown that up to ninety per 22 cent of labour expended in preparing a metal plate component 23 is not actually adding value to the plate. In addition, 24 many of the drilling machines presently in use have serious limitations on the size of plate that can be accepted for 26 drilling and even these machines are extremely expensire.

27 Brief Summary of the Invention and Objects: 28 It is an object of the present invention to provide a 29 plate working machine by means of which the labour cost associated with the fabrication of metal plate components 31 may be reduced.

32 The invention accordingly provides a plate working 33 machine comprising means for supporting a metal plate to be 34 worked in a generally horizontal plane, a pair of rails extending along the sides of said plate supporting means, 36 driven support means engaging said rails for travel 37 therealong, said support means comprising a spaced pair of 38 support beams extending from one rail to the other and i WO 88/09236 PCT/AU88/00149 -2 1 joined at either end by cross members, means for supporting 2 drilling means between said support beams, said supporting 3 means being mounted on tracks on said beams, and drive means 4 for moving said drilling means along said support beams from one side of said plate supporting means to the other.

6 The machine preferably includes profile cutting means 7 munted on said supporting means for said drilling means and 8 extending over one of said beams and downwardly towards a 9 position adjacent said plate supporting means.

In a preferred form of the invention, the tracks on 11 the beams are secured to the top of one beam and to the 12 bottom of the other beam. This positioning of support means 13 provides optimum location of drill support means, thus 14 reducing deflection of the drilling means due to drilling forces.

16 Movement of the support means along the rails and the 17 drilling and profiling means along the beams is achieved by 18 electric motors, each of which drives a gear box and a pair 19 of pinion gears which mesh with racks mounted on the top of one of the rails and on the top of one of the support beams.

21 Each gearbox is preferably provided with a gear 22 arrangement which biases said pinions in opposite 23 directions so that the pinions engage opposing faces of the 24 teeth of the rack to thereby reduce the backlash in the drive system to a minimum. It will be appreciated that 26 accurate positioning of the drilling means and the profile 27 cutting head is extremely important and for this reason the 28 avoidance of backlash in the drive system is paramount.

29 In a preferred form of the invention, the plate working machine also includes means for marking the plate to be 31 worked for subsequent bending and/or welding operations.

32 It will be appreciated from the above that the 33 necessary drilling, tapping cr counterboring, profile 34 cutting, and if desired line marking, may be performed on the metal plate to be worked without moving the plate from 36 the plate supporting means. 1,s a result of this 37 arrangement, the plate working operations may be performed 38 far more efficiently with significant reductions in nonii: N 1 1 -3 productive labour content. The cutting head of the profile cutting means and the drilling head of the drilling means may be accurately positioned by movement of the driven support means on which the support beams are mounted and by the drive means for moving the drilling means across the support beams.

The accurate positioning of the drilling means and cutting head, as well as the other operations performed by the machine, are controlled by a computerised numerical control system mounted at one end of the front support beam. The control system is programmed to automatically perform all movements and machine operations necessary to process large plates into finished parts. Since the support beams may be relatively long (of the order of four metres) compared to other drilling and profiling machines, and the plate supporting means may be of any desired length, but conveniently of the order of 16 metres, plates of substantial dimensions may be accommodated by the machine.

When a metal plate is drilled, tapped or counterbored, it is important that the plate be maintained in a stationary position with respect to the drilling head. At the present time, this is usually achieved by means of hydraulically operated clamping feet which apply substantial forces to the plate and therefore require substantial support structures to ensure that deflection of the plate and the drill support structure during drilling, and especially at the point of break-through, are minimized.

In a preferred form, the machine includes a clamping means comprising at least one clamping foot positioned to engage the plate to be worked, means for applying a substantially perpendicular clamping force to the plate to be worked through said foot and means for locking the clamping foot in the clamped k tbspe/farley.spe 91 7 31 WO 88/09236 PCT/AU88/00149 -4- 1 position whereby the means applying the clamping force may 2 be deactivated to reduce the loads applied to the structure 3 supporting the clamping foot during plate working 4 operations.

In a preferred form, a single clamping foot which 6 partially surrounds the intended drilling portion is 7 provided.

8 In a third aspect, the invention provides a plate 9 working machine comprising means for supporting a metal plate to be worked in a generally horizontal plane, a pair 11 of rails extending along the sides of said plate supporting 12 means, driven support means engaging said rails for travel 13 therealong, said support means comprising a spaced pair of 14 support beams extending from one rail to the other and joined at either end by cross members, means for supporting 16 drilling means between said support beams, said supporting 17 means being mounted on tracks on said beams, and drive means 18 for moving said drilling means along said support beams from 19 one side of said plate supporting means to the other, plate clamping means supported by said means supporting said 21 drilling means, means for applying a clamping force to said 22 plate through said clamping means, said force being selected 23 to be larger than the greatest expected drilling force, and 24 means for locking the clamping means in its clamped position while said clamping force is applied to said plate.

26 It will be appreciated that by locking the clamping 27 means in the plate clamping position, additional vertical 28 forces due to plate working operations will not be added to 29 the total vertical force on the supporting structure, as in prior art arrangements described above, and the total 31 vertical load on the supporting structure is the greater of 32 the forces applied by the plate working means or the 33 clamping force. Thus, of the clamping force is always 34 greater than the drilling force, then the total vertical load on the support structure will b- invariant durinpl at%\ 36 dr:lling operations, thus ensuring no change in v&ttic.al' i 37 position of the drilling means during drilling opera.tions, 38 Conventional designs must be much more rigid to e.e jLU WO 88/09236 PCT/AU88/00149 5 vertical movement as the total vertical force changes during drilling operation. In the case of the preferred embodiment described in greater detail below, the support beams are designed for loads of about 4 tonnes rather than' loads of about 15 tonnes would be required if a prior art clamping mechanism were to be used.

In a particularly preferred form of the above aspect, the locking means may comprise a deformable sleeve surrounding a piston rod extending from the means for applying the clamping force, said sleeve being deformed into locking engagement with said piston rod by means of fluid pressure to thereby lock the clamping feet in position.

Brief Description of the Drawings: One presently preferred form of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective schematic view of the machine embodying the invention; Figure 2 is a fragmentary front elevation of the machine; Figure 3 is a fragmentary sectional end elevation of the drilling means and profile cutting support means; Figure 4 is a detailed sectional elevation of the locking means for the clamping foot means; Figure 4A is a plan view showing the shape of the clamping foot; Figure 5 is a fragmentary front elevation of the drilling means showing the drive arrangement therefor; Figure 6 is a sectional end elevation of a gearbox and pinion arrangement suitable for driving the support means along the rails and for driving the drilling means and profiling means across the support beams; Figures 7, 9, 11 and 13 are schematic diagrams of drilling mechanisms according to the prior art, and Figures 8, 10, 12 and 14 are similar schematic diagrams showing the drilling mechanism embodying the invention.

Referring firstly to Figure 1 of the drawings, the plate working machine embodying the invention will be seen

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33 34 36 37 38 i f I:i i j :i i:Ei :lin WO 88/09236 PCT/AU88/00149 1 to comprise a metal plate supporting table 1 including an 2 array of upstanding support pins P of aluminium or similar 3 soft metal surrounded by an edge frame F, a pair of rails 2, 4 3 extending along the sides of the table 1, a driven support means 4 for travel along the rails 2, 3, said support means 6 4 comprising a-spaced pair of support beams 5, 6 extending 7 from one rail to the other and joined at either end by cross 8 members 7 and 8. A drilling assembly 9 is mounted on tracks 9 10 and 11 (Figures 2 and 3) on the beams 5 and 6, and a high speed oxy/plasma profiling head 12 of known construction is 11 carried by the drilling assembly 9 and extends over the 12 beam 6 and downwardly towards a position adjacent the table 13 1.

14 As will be seen from Figures 1, 2, 3 and 5 of the drawings, the support pins P have a pointed tip to minimise 16 contact between the pins and the workpiece W and the pins P 17 are arranged in arrays which are skewed at about 15° to the 18 ends of the frame F. The frame F is adapted to contain water 19 or other suitable coolant which is maintained in the frame F to a level approximately coincident to the tips of the pins 21 P (Figuress 3 and The pins P are removably attached to 22 support bars B adjustably supported within the frame F by 23 support frame S, as shown in Figure 2. The use of aluminium 24 or similar soft metal for the pins P is preferred since less damage will be caused to the drilling tip as it breaks 26 through a hole which happens to be coincident with a support 27 pin P. The pins P also serve to conduct plasma current from 28 the workpiece W to earth in the event that plasma cutting is 29 performed at the same time as drilling operations. The use of pointed tips on the pins serves to minimise degradation 31 of profile cutting operations.

32 Referring now to Figure 2 of the drawings, the rail 2 33 comprises a supporting structure 13 on which is mounted a 34 base rail member 14 and a laterally extending rail member engaged by upper and lower roller bearings 16 and 17 mounted 36 on a lower extension of the cross member 7. The rollers 16 37 and 17 support their end of the support structure for 38 movement along the rail 2, the lower roller bearing 16 I

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0 .PC T/AU' 1 i O88/09236 PCT/AU88/00149 7 1 2 3 4 6 7 8 9 11 12 13 14 16 17 18 19 21 22 23 24 26 27 28 29 31 32 33 34 36 37 38 preventing upward movement of the support structure during drilling operations.

The rail 3 comprises a similar supporting structure 18 carrying a linear track 19 engaged by a linear bearing and a rack 21 engaged by drive pinions 22 driven by an electriC motor 23 through a gearbox 24 to be described in greater detail below. It will be appreciated that since the linear bearing 20 substantially encloses the rounded section of the linear track 19, upward movement of the support structure with respect to the track 3 is resisted.

Referring now to Figures 3 and 4 of the drawings, the drilling assembly 9 comprises a structurally rigid outer housing 25 carrying laterally extending supports 26 and 27 at upper and lower positions of opposed sides of the housing 25. The supports 26, 27 carry track engaging structures 28 and 29 which engage the tracks 10 and 11 mounted on the upper face of the support beam 6 and on the lower face of the support beam 5 respectively, as clearly shown in Figure 3 of the drawings. The tracks 10 and 11 are of an inverted wedge shape and the track engaging structures 28 and 29 have a corresponding profile. This arrangenient minimizes the upward and downward movement of the housing 25 with respect to the support beams 5 and 6.

The support beam 6 also carries a rack 30 engaged by a pair of drive pinions 32 driven by an electric motor 33 via a gearbox 34. The gearbox arrangement will be described in greater detail below. Thus, the motor 33 drives the pinions 32 through the gearbox 34 and the drilling assembly 9 is moved in either direction across the support beams 5 and 6 on the tracks 10 and 11. Since the tracks 10 and 11 are arranged in the manner shown in Figure 3 of the drawings, movement of the drilling assembly 9 as a result of the torsional forces applied during drilling operations will be minimized. Thus, the drilling assembly 9 may be accurately positioned with respect to the workpiece W supported on the table 1 without the need to compensate for torsional movements caused by the drilling operation. The extreme positions of the drilling assembly 9 with respect to the c I.

WO 88/09236 PCT/AU88/00149 8 1 support beams 5 and 6 is controlled by limit switches 2 one of which is shown in Figures 1 and 3 of the drawings.

3 The above advantage will be more clearly appreciated by 4 reference to Figures 7 12 of the drawings which compare the apparatus of the embodyment with prior art arrangements.

6 Referring first to Figures 7 and 8, it will be noted that 7 the drilling thrust T applied to the drilling assembly 9 8 will be equally divided between the beams 5 and 6 via the 9 linear bearings. Thus the distortion of the prior are drill box clearly shown in Figure 7 of the d'rawings is 11 substantially eliminated.

12 Referring now to Figures 9 and 10, because the drilling 13 thrust T is taken equally by the beams 5 and 6, the moment 14 arm TL present in the prior art arrangement shown in Figure 9 of the drawings is avoided, thus reducing the twisting 16 moments applied to the beams. Similarly, as shown in Figures 17 11 and 12, because the drilling thrust force is taken 18 equally by the beams 5 and 6, the vertical deflection of 19 each beam will be the same, thereby avoiding the nonvertical movement of the prior art arrangement shown in 21 Figure 11 of the drawings.

22 As shown best in Figure 3, the housing 25 encloses a 23 drill carriage 36 mounted for vertical movement in linear 24 bearings 37 and carrying an automatic drill changer 38 cooperating with a drill head 39, both of known 26 construction. The mechanism is enclosed within a protective 27 bellows 40 and is driven by an'electric motor 41 through 28 toothed drive belt 42 and ball screw 42A.

29 The housing 25 also carries a shaped pneumatically operated clamping foot 43 by means of which the workpiece W 31 is clamped against the table 1 during the drilling and other 32 operations. As shown in Figure 3, the clamping foot 43 is 33 attached to the piston rods 45 of a pair of pneumatic 34 cylinders 46 and includes a novel clamping mechanism 47, shown in enlarged detail in Figure 4.

36 The clamping mechanism 47 includes a composite locking 37 sleeve 48 comprising a fluid-impervious nylon outer sleeve 38 49 and an inner brass s leeve 50 formed with i, j 'l WO 88/09236 PCT/AU88/00149 -9- 1 circumferentially space slits (not shown) which increase the 2 flexibility of the brass sleeve 50. The composite sleeve 48 3 is located by annular end fittings 51, 52 and the sleeve 48 4 is surrounded by a body 53 formed with a cavity 54 into which high pressure hydraulic fluid may be injected. It 6 will be appreciated that as the fluid under pressure is i 7 injected into the cavity 54, the composite sleeve 48 is 8 distended inwardly until the brass sleeve 50 makes contact 9 with the piston rod 45 to thereby clamp the piston rod 45 in any desired extended position.

11 As shown in Figure 4'A, the clamping foot 43 has a 12 generally U-shaped central portion 44 which in use surrounds 13 that portion of the'workpiece W which is being drilled. The 14 shape of the foot 43 serves to ensure that the wor.kpiece W is clamped immediately adjacent the working area whereby 16 maximum rigidity of the workpiece during drilling is 17 ensured. In this way, the workpiece W will be held against 18 rotation due to the applied drilling torque and that portion 19 of the workpiece W between the lines of applied force of the pneumatic cylinders 46 will be held against buckling 21 resulting from the applied drilling thrust.

22 The clamping foot 43 is found with internal passages 23 43a through which water flows to openings (not visible) in 24 the b.ttom face and the inner face of the central portion 44 of the foot 43 at the positions 43b and 43c respectively.

26 Water enters at 43d and is discharged through these openings 27 at 43b and 43c to create a hydrodynamic bearing under the 28 foot 43 and to assist in removing swarf from the drilling 29 region.

To further ensure maximum rigidity during drilling, the 31 computerised operating system of the machine is programmed 32 to apply a large initial load to the clamping foot 43, 33 preferably of the order of 50% greater than the maximum 34 drilling thrust force, by means of the pneumatic cylinders 46, to cause an upward deflection of the beams 5 and 6. The 36 piston rods 45 are then rigidly clamped in positi( jy means 37 of the hydraulic clamping mechanisms 47 whereby a rigid link ji 38 is created between the drilling assembly 9 and the clamping i 1 WO 88/09236 PCT/AU88/00149 i 1 foot 43. In this way, any variation in the drilling force, 2 as invariably occurs during drilling, will have little 3 effect on the vertical deflection of the drilling assembly 9 4 by virtue of the pre-loading applied by the deflected beams 5 and 6 via the rigid link referred to above. The 6 improvement in drilling performance introduced by this 7 arrangement will be better understood by consideration of 8 Figures 13 and 14, comparing the arrangement of the present 9 invention with the prior art. In these figures, KB equals beam stiffness, FD equals drilling force, FR equals beam and 11 drill weight on rails, FC equals clamping force and KC 12 equals clamping foot stiffness.

13 As will be clearly appreciated from Figures 13 and 14, 14 when a drill is about to pierce through the workpiece W, the resistance of the workpiece to the drill thrust is reduced 16 and it is possible for the applied drill thrust force to 17 "punch out" the last part of a h o e. This is most 18 undesirable as the drill can be damaged and the drill hole 19 not properly formed. The above described arrangement reduces this effect greatly because of the higher stiffness between 21 the workpiece on the drilling assembly 9 afforded by the 22 stiffness KC of the clamping foot 43. This advantage is not 23 present in the prior art arrangements which apply a constant 24 clamping force FC using pneumatic cylinders only since the plate clamping means does not increase the plate-to-drilling 26 assembly stiffness in any way. Also, the large vertical pre- 27 load applied to the drilling assembly 9 pre-loads the li'near 28 bearings linking the drilling assembly 9 to the beams 5 and 29 6. This increases the stiffness of the linear bearings which in turn improves the location of the drilling assembly 9 31 leading to improved drilling accuracy and operation.

32 Referring now to Figure 5 of the drawings, the drill 33 head 39 will be seen to be driven by an electric motor 34 via a toothed belt 56. A coolant injector 57 is provided to inject coolant through the main drive shaft of the drill 36 head 39 in a manner known in the art. Further coolant may 37 be injected onto the workpiece W via coolant tube 58. I 38 A tool changing mechanism 59 of known construction WO 88/09236 PCT/AU88/00149 11 1 extends to one side of the housing 25 and by means of which 2 drills and other tools (not shown) mounted on a rotary 3 holder 60 may be transported into position for fitting to 4 the drill head 39. Since the tool changer is of known construction, further description thereof is not required.

6 Referring now to Figure 6 of the drawings, the gearbox 7 shown in section is typical of the gearboxes 24 and 34, 8 although the ratios in each gearbox are of course different.

9 The pinions 22 (32) have their shafts 61, 62 mounted in spaced tapered roller bearings 63, 64 and 65, 66 mounted in 11 the gearbox housing 67. Each shaft 61, 62 carries a gear 12 68, 69 each of which meshes with a gear 70, 71 carried on a 13 drive shaft 72 which is driven by the electric motor 23 (33) 14 via a toothed belt drive 73a engaging a toothed drive head 73.

16 It will be noted that the gears '70 and 71 are 17 oppositely bevelled so that the gears 68 and 69 and thus the 18 shafts 61 and 62 are biased outwardly whereby the pinions 22 19 (32) are forced onto opposing faces of the teeth of the rack whereby little or no backlash is evident in the pinion 21 drive. The importance of reducing backlash to a minimum is 22 of course important where accuracy of positioning of the 23 apparatus with respect to the workpiece W is paramount.

24 As mentioned above, the operations of the electric motors 23 and 33 is controlled by a computer numerical 26 control system C mounted in the cross member 8. The control 27 system is programmable to perform repetitive operations on 28 the workpiece W but may be manually controlled if desired.

29 The control system includes a VDU and keyboard to enable the creation, deletion or modification of controlling 31 programmes. Alternatively, a programme may be loaded 32 directly from a separate computer system. The control 33 system also controls the motors 41 and 55 to control the I 34 depth of penetration of the tool carried by the drill head 39 as well as the direction of rotation of the drill head 36 39. Similarly, coolant fluid flow and the operation of the 37 plasma and oxy/fuel torches are controlled by the control 38 system C. As also mentioned above, a plate marking system, a makn sy WO 88/09236 12 1 such as a flame powder marker of known const 2 mounted on the structure 12 to enable the wo 3 marked for subsequent bending and welding ope w.

PCT/AU88/00149 ruction, may be rkpiece W to be *rations.

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Claims (12)

1. 13 Claims 1. A plate working machine comprising means for supporting a metal plate to be worked in a generally horizontal plane, a pair of rails extending along the sides of said plate supporting means, driven support means engaging said rails for travel therealong, said support means comprising a spaced pair of support beams extending from one rail to the other and joined at either end by cross members, means for supporting drilling means between said support beams, said supporting means being mounted on tracks on said beams, and drive means for moving said drilling means along *said support beams from one side of said plate :supporting means to the other. g* 15

2. The machine of claim 1, wherein said tracks on said beams are secured to the top of one beam and to the bottom of the other beam.

3. The machine of claim 1, wherein movement of the j support means along the rails and the drilling means 20 along the beams is achieved by electric motors, each of which drives a gear box aud a pair of pinion gears which mesh with racks mounted on the top of one of tLe rails and on the top of one of the support beams.

4. The machine of claim 3, wherein each gearbox is preferably provided with a gear arrangement which biases said pinions in opposite directions so that the pinions engage opposing faces of the teeth of the rack to thereby reduce the backlash in the drive means to a minimum.

5. The machine of any preceding claim, further comprising a clamping means comprising at least one clamping foot positioned to engage the plate to be worked, means for applying a substantially perpendicular clamping force to the plate to be worked through said foot and means for locking the clamping foot in the clamped position whereby the means applying the clamping force may be deactivated to reduce the loads applied to the structure supporting the clamping foot during plate I working operations. tbspe/farley.spe 91 7 31 l, 32 The invention accoraingLy pLuv u. 33 machine comprising means for supporting a metal plate to be 34 worked in a generally horizontal plane, a pair of rails extending along the sides of said plate supporting means, I 36 driven support means engaging said rails for travel I 37 therealong, said support means comprising a spaced pair of 38 support beams extending from one rail to the other and o. 1 i -14

6. A plate working machine comprising means for supporting a metal plate to be worked in a generally horizontal plane, a pair of rails extending along the sides of said plate supporting means, driven support means engaging said rails for travel therealong, said support means comprising a spaced pair of support beams extending from one rail to the other and joined at either end by cross members, means for supporting drilling means between said support beams, said supporting means being mounted on tracks on said beams, and drive means for moving said drilling means along said support beams from one side of said plate supporting means to the other, plate clamping means supported by said means supporting said drilling means, means for applying a clamping force to said plate through said clamping means, said force being selected to be larger than the greatest expected drilling force, and means for locking the clamping means in its clamped position while said clamping force is applied to said 20 plate.

7. The machine of claim 5 or 6, wherein said clamping foot has a portion which partially surrounds the region of said plate to be worked.

8. The machine of claim 5 or 6, wherein said clamping foot includes liquid receiving passages which open under the foot to create a hydrodynamic bearing under the foot and in the region of the plate to be worked.

9. The machine of any one of claims 5 to 8, wherein said locking means comprises a deformable sleeve surrounding a piston rod extending from the means for applying the clamping force, said sleeve being deformed into locking engagement with said piston rod by means of fluid pressure to thereby lock the clamping feet in position.

10. The machine of any preceding claim, further -LA comprising profile cutting means mounted on said Csupporting means for said drilling means and extending over one of said beams and downwardly towards a position xI adjacent said plate supporting means. tbspe/farley.spe 91 7 31I 4 r 15 I

11. A plate working machine substantially as hereinbefore described with reference to the accompanying drawings.

12. The machine of any one of claims 5 to 10, wherein said clamping means is substantially as described with reference to the accompanying drawings. DATED this 31 July 1991 CARTER SMITH BEADLE Fellows Institute of Patent Attorneys of Australia Patent Attorneys for the Applicant: FARLEY MANUFACTURING PTY.LTD. r rr r V II tbspe/farley.spe 91 7 31