GB2205518A

GB2205518A - Window refurbishing by machining

Info

Publication number: GB2205518A
Application number: GB08713536A
Authority: GB
Inventors: Edward Henry Mountford
Original assignee: EMI MEC Ltd
Current assignee: EMI MEC Ltd
Priority date: 1987-06-10
Filing date: 1987-06-10
Publication date: 1988-12-14
Also published as: DE3819666A1; GB8713536D0

Description

k 1 1 n ' 5 1 MI ZM 0 1 - 1 - IMPROVEMENTS IN OR RELATING TO WINDOW

REFURBISHING MACHINES The present invention relates to Improvements in or relating to window refurbi.shing machines, including a method and apparatus for such refurbishments.

In windows which are used on aircraft, the surfaces of those windows, and in particular the outwardly facing surface of the outer window, tend to become marked with small scratches, some of which are caused by minute particles In the air scraping against the window surface during the flight of the aircraft.

After a period of time, typically a year, these small scratches cause a hazy effect and detract from the ability of a passenger to see through the window.

Accordingly, if the window is to be made clear again it is necessary to remove these small scratches.

In a prior proposal for removing the scratches the window Is polished by holding the window stationary and pulling a band of abrasive material across the window. The size of the particles comprising the abrasive material must be extremely small i.f the scratches which are caused by the passage of the abrasive material over the window are to be such that they are not obviously visible to the eye. However, one disadvantage of having such small abrasive particles in the abrasive material 1 s that the po 1 1 sh 1 ng of the w 1 ndow takes an extremely long time.

According to one aspect of the present invention, a method of refurbishing a window comprises retaining a window in position with a suction force exerted on one side of the window, and causing relative rotational movement between a cutting tool and the window and causing relative translational movement of the cutting tool and the window such that the cutting tool removes a portion of the other side of the window.

The method may Include exerting a suction force on a curved window and causing the window to be sucked f lat.

The method may further comprise causing rotational movement of the window and/or causing relative translational movement of the tool The method may comprise causing rotational movement of the window and causing the tool to cut the surface of the rotating window at the centre of the axis of rotation.

The method may comprise causing relative translational movement of a plurality of cutting tools and the window. The method may comprise removing a greater depth of material with the first cutting tool In the direction of relative translational movement than the depth which Is removed with the or a subsequent cutting tool.

The method may further comprise retaining the window In position by exerting a suction force on said other side of the window, after said other side of the window has had a portion removed by the cutting tool, and then causing relative translational and rotational movement of the cutting tool and window to remove a portion of said one side of the window. The method may additionally comprise the steps of exerting a suction force on said other side of the window after a portion of said other side has been removed, releasing the suction force on said one side of the window, subsequently moving the window to another position and then exerting a suction force on said one side of the window and releasing the suction force on said other side of the window and returning the window so that a suction force Is exerted on said other side of the window.and the suction force on said one side of the window Is released, and then causing relative rotational and translational movement of the window and cutting tool to remove a portion of said one side of the window. The method may further comprise maintaining a normally curved window flat between the period when a portion of said other side of the window Is removed and when a portion of said one side of the window is removed.

According to another aspect of the present Invention, a window refurbishing apparatus comprises suction means arranged to exert suction force on one side of a window and thereby hold the window, rotational drive means arranged to cause relative rotational movement between a window held by the suction means and a cutting tool, and translational drive means arranged to cause relative translational movement between a window held by the suction means and the cutting tool.

The suction means may Include a flat portion against which a window can be held. The suction means may include a continuous seal against which a side of a window Is arranged to bear. The seal may be arranged to stand proud of the flat portion but be capable of lying flush with the flat portion when a window is held by the suction means.

Adjustment means may be provided to enable the relative translational movement caused by the translational drive means of the cutting tool and a window held by the suction means to be coincident with the rotational axis of the rotational drive means. The apparatus may include a plurality of cutting tools and the adjustment means may be arranged to cause simultaneous movement of each of the cutting tools. The adjustment means may comprise a wedge member movable between two opposed surfaces, one of which Is fixed relative to the other which carries the tool or tools.

Movement of the wedge relative to the surfaces may be JO arranged to Increase or decrease the distance between the opposed surfaces.

The apparatus may further comprise a probe arranged to provide an indication of the distance of a side of a window to have a portion thereof removed from the cutting tool. The probe may Include Infra red means.

According to another aspect of the present Invention a tool adjustment apparatus Includes a first portion fixed relative to a second portion which carries a tool and an adjustment member arranged to cooperate with the first and second portions movement of the adjustment member in a first direction relative to the first and second portions being arranged to cause relative movement of the first and second portions In a second direction transverse to the first direction.

The adjustment member may comprise a wedge member. The adjustment member may Include a threaded 30.

portion with which a rotatable threade d member cooperates whereby rotatable movement of the threaded member causes translational movement of the adjustment member.

The cooperation of the adjustment member with the first and second members may be such t-hat movement of the adjustment member in the f Irst direction to a certain extent causes movement of the second member relative to the first member to a lesser extent.

According to a further aspect of the. present invention, a rotatable workplece holder comprises a casing including an inner portion of hardenable material which has been inserted Into the casing prior to the material hardening. Such a holder Is particularly useful JO where the casing Is of aluminium which Is, i n use, ar ranged to rotate at re 1 at 1 ve 1 y h 1 gh speeds as, without the inner portion, the aluminium may expand or flutter when rotating, which is clearly not desirable when working on a workpiece rotating with the holder.

The Inner portion may, when hardened, be of greater rigidity than the casing. The Inner portion may be adhered or bonded to the casing. The Inner portion may Include epoxy resin and/or reconstituted granite.

According to another aspect of the present invention a method of forming a rotatable workplece holder comprises Inserting a hardenable material Into a casing prior to the material hardening.

The present invention also Includes a workpiece which has been refurbished by a method or apparatus as herein referred to.

The Invention may be carried Into practice In various ways, but several embodiments will now be described way of example and with reference to the accompanying drawings, In which:

Figure 1 Is a schematic view from the front of a window holding plate 10 of a window refurbishing machine; Figure 2 Is a schematic plan view of an automated window refurbishing arrangement Including two window refurbishing machines 12 and 112; Figures 3A and 3B are a side and an end sectional view respectively of a tool holder 14, and Figure 4 Is a cross-sectional view through the window holding plate 10.

As shown In Figure 1, the window holding plate carries a window 16 on Its front facing surface 18. The plate Is arranged to rotate about an axis 20, and a tool carrier 22 Is slidably mounted to move across the surface 18 of the plate.

A scratched window Is refurbished as follows.

The window Is placed against the plate 10, with either Its convex or concave side facing the plate, such that a flexible lip seal 24 protruding from the front face of the plate is engaged by the window. The surface of the plate Includes a network of channels 26 to which a vacuum of the order of 12 pounds per square Inch Is applied, and that vacuum pulls the window flat against the plate 10 and causes the window to push the lip seal 24 flush with the surface of the plate.

A sensor Indicated schematically at 28 then determines the distance of the surface of the window facing away from the plate from the tool holder and the gap between the surface of the plate and the tool holder Is adjusted, If necessary.

The plate 10 is then rotated at 3000 revs per minute about the axis 20.

The tool carrier 22 Is then moved across the surface of the plate such that three diamond tools 30, 32 and 34 (shown In Figure 3) mounted on the tool holder 14 pass along the phantom line 38 shown In Figure 1 coincident with the rotational axis 20 of the plate.

The first tool 30 removes 51100'ths of an inch from the surface of the window, the next tool 32 removes 3/100'ths from that surface and the final tool 34 removes 1/100'ths of an Inch. Once the final tool 34 has passed the axis 20 the tools are then returned to the position shown in Figure 1 having first been moved away from the surface of the window being cut.

In order to refurbish the opposite side of the window the plate Is stopped, the vacuum holding force relieved, and the window turned round whereupon the above described sequence Is repeated.

Figure 2 shows an automated window refurbishment arrangement Including two refurbishing machines 12 and 112 including respectively a window holding plate 10 and and a tool carrier 22 and 122 as previously described.

The machines 12 and 112 are located on either side of a transporting arm 40 which is pivotally mounted at one end about an axis 42 and has a pair of suction plates 44 and 46 pivotally mounted at its other end about a first axis 48 coincident with the longitudinal extent of the arm 40 (either separately or together) and about a second horizontal axis 50 perpendicular to the first axis 40.

1 n use, a w I ndow 16 approaches the arm. 40 on a conveyor 52, and the arm 40 Is located such that the plate 46 Is over the window 16. The plate 46 Is then lowered onto the window 16 by pivoting the arm 40 downwardly about a horizontal axis-36 extending through the axis 42. A suction force Is then applied to grip the window and pull it flat against the plate 46.

The arm 40 Is then raised and pivoted about the axis 36 so that the window 16 is opposite the plate 10, and the plate 46 Is then pivoted In a clockwise direction about the horizontal axis 50 until the exposed surface of the window faces the plate 10. The window Is then advanced to contact the plate 10 by sliding the arm 40 on a bar 54. When that contact Is made, the suction force on the plate 10 is applied to thewindow 16 to grip and retain the window flat, and the suction force on the p 1 ate 46 1 s removed to a 1 1 ow the arm to be used i n transporting a second window 116 to the machine 112, or turn round a window at the machine 112 or remove a refurbished window from the machine 112, as described below In relation to the machine 12.

The window at the machine 12 Is then refurbished as described previously In relation to Figure 1.

In order to turn the window 16 around and refurbish the other side, the plate 46 Is returned to abut the refurbished side of the window 16 and the suction force Is applied to the plate 46 to hold and retain the window flat, and the suction force on the plate 10 Is removed. The plate 46 Is then moved away from the plate 10 by sliding the arm 40 along the bar 54.

The plate 46 can then be pivoted about the axis 48 relative to the plate 44_ such that the refurbished side of the window abuts the plate 44. A suction force is then applied to the plate 44 to grip and retain the w 1 ndow f 1 at and the suct 1 on f orce 1 s then removed f rom the p 1 ate 46 to a 1 1 ow the p 1 ate 46 to be p i voted away from the plate 44.

The plate 44 Is then manoeuvred such that the refurbished side abuts the plate 10, and the suction f orce i s then app 1 1 ed to and subsequent 1 y removed f rom the plates 10 and 44 respectively. The other side of the window Is then refurbished as previously described whilst the transporting arm is free to carry out operations in relation to the other machine 112.

When both sides of the window have been refurbished the plate 46 picks up the window from the plate 10 and deposits the window on a further conveyor 56.

Thus the machines 12 and 122 refurbish both sides of alternate windows advancing on the conveyor 52, and refurbished windows are removed by the conveyor 56.

Figures 3A and 313 show the detail of the tool holder 14. The tool holders 14 are preset before they are mounted in the tool carrier 22 and thus, when the tools 30, 32 and 34 require replacement a preset holder may replace the previous holder without delaying the refurbishing operation significantly.

Each tool Is mounted In a respective block 58, 60 and 62 and a rod 64 extending through the blocks constrains each block to move or pivot together. A wedge 66 Is located between the central block 60 and a base 68 and the wedge 66 ca.n be moved downwardly with respect to Figure 3B by tightening up a nut 70 on a threaded Shaft 72 connected to the wedge to move each tool to the right when viewed In that figure.

Alternatively the tools can be moved to the left by slackening the nut and allowing the wedge to move upwardly. The purpose of the tool adjustment effected by the wedge i s to ensure that the too 1 s are a 1 1 1 n a 1 1 ne which passes through the centre of the rotational axis 20 of the plate 10, and the accuracy of the adjustment may be to within 1/4000 of an Inch.

Figure 4 is a cross-sectional view through the centre of the plate 10 showing two aluminium parts 74 and 76 which are connected together by screws 78 to define four cavities 80 (only two of which are shown) located symmetrically about the rotational axis 20. The aluminium part 76 is provided with four filler holes 82 through which a material 84 comprising reconstituted granite with epoxy resin is poured to fill and set in the cavities 80.

The aluminium provides a light weight plate. The material 84 Is approximately the same density as aluminium but is much more rigid and thus tends to stop or 1 nh 1 b i t any f 1 utter wh 1 ch may tend to occur when a disc comprising solely aluminium is rotated.

Referring again to Figure 1, It will be noted that an additional 1 1 p sea 1 86 surrounds the sea 1 24.

The function of the seal 86 Is to allow the disc to hold windows of a larger size than those which may be held by the seal 24, as the concave surface of such a large window may not abut the protruding lip seal 24 to enable the suction force to be applied.

When a window is being refurbished by the machine shown in Figure 1 or 2 the refurbishment may take place in an enclosed area which may be provided with an extractor fan arranged to remove the portions of the windows which are taken off.

1 CLA 1 MS.

1. A method of refurbishing a window comprising retaining a window In position with a suction force exerted on one side of the window, and causing relative rotational movement between a cutting tool and the window and causing relative translational movement of the cutting tool and the window such that the cutting tool removes a portion of the other side of the window.

Claims

2. A method as claimed In Claim 1 Including exerting a suction force on a

curved window and causing the window to be sucked flat.

3. A method as claimed In Claim 1 or Claim 2 comprising causing rotational movement of the window.

4. A method as claimed In any preceding claim comprising causing translational movement of the tool.

5. A method as claimed In Claim 3, and Claim 4 when dependent upon Claim 3, comprising causing the tool to cut the surface of the rotating window at the centre of the axis of rotation.

6. A method as claimed In any preceding claim comprising causing relative translational movement of the window and a plurality of cutting tools.

7. A method as claimed In Claim 6 comprising removing a greater depth of material with a first cutting tool in the direction of relative translational movement than the depth which is removed with the or a subsequent cutting tool.

8. A method as claimed in any preceding claim comprising retaining the window in position by exerting a suction force on said other side of the window, after sai-d other side of the window has had a portion removed by the cutting tool, and then causing relative translational and rotational movement of a cutting tool and window to remove a portion of said one side of the w 1 ndow.

9. A method as claimed In Claim 8 comprising the steps of exerting a suction force on the other side of the window after a portion of said other side has been removed, releasing the suction force on said one side of the window, subsequently moving the window to another position and then exerting a suction force on said one side of the window and releasing the suction force on said other side of the window and returning the window exerting a suction force on said other side of the window and releasing the suction force on said one side of the window, and then causing relative rotational and translational movement of the window and the cutting tool to remove a portion of said one side of the window.

10. A method as claimed In Claim 9 comprising maintaining a normally curved window flat between the period when a portion of said other side of the window is removed and when a portion of said one side of the window is removed.

11. A method of refurbishing a window substantially as herein described with reference to, and as shown in the accompanying drawings.

12. A window refurbishing apparatus comprising suction means arranged to exert a suction force on one side of a window and thereby hold the window, rotational drive means arranged to cause relative rotational movement between a window held by the suction means and a cutting tool, and translational drive means arranged to cause relative translational movement between a window held by the suction means and a cutting tool.

13. Apparatus as claimed in Claim 12 In which the suction means includes a flat portion against which a window can be held.

14. Apparatus as claimed In Claim 12 or Claim 13 In which the suction means includes a continuous seal against which a side of the window Is arranged to bear.

15. Apparatus as claimed in Claim 13 and Claim 14 In which the seal is arranged to stand proud of the f lat portion but be capable of lying flush with the flat portion when a window Is held by the suction means.

16. Apparatus as claimed in any of Claims 12 to 15 including adjustment means arranged to enable the relative translational movement caused by the translational drive means of the cutting tool and the window held by the suction means to be coincident with the rotational axis of the rotational drive means.

17. Apparatus as claimed In any of Claims 13 to 16 Including a plurality of cutting tools.

18. Apparatus as claimed In Claim 16 and Claim 17 In which the adjustment means is arranged to cause simultaneous movement of each of the cutting tools.

19. Apparatus as claimed In any of Claims 16 to is In which the adjustment means comprises a wedge member movable between two opposed surfaces, one of which Is fixed relative to the other which Is constrained to move with the tool or tools.

20. Apparatus as claimed i.n Claim 19 In which movement of the wedge relative to the surfaces Is arranged to increase or decrease the distance between the opposed surfaces.

21. Apparatus as claimed In any of Claims 13 to 20 comprising a probe arranged to provide an indication of the distance of a side of a window to have a portion thereof removed from the cutting tool.

22. Apparatus as claimed In Claim 21 In which the probe Includes infra-red means.

23. A window refurbishing apparatus substantially as herein described with reference to, and as shown In the accompanying drawings.

24. A tool adjustment apparatus including a first portion fixed relative to a second portion which Is constrained to move with the tool, and an adjustment member arranged to co-operate w I th the f I rst and second portions, movement of the adjustment member in a first direction relative to the first and second portions being arranged to cause relative movement of the first and second portions in a second direction transverse to the first direction.

25. Apparatus as claimed In Claim 24 in which the adjustment member comprises a wedge member.

26. Apparatus as claimed in Claim 24 or Claim 25 in which the adjustment member Includes a threaded portion with which a rotatable threaded member co-operates whereby rotational movement of the threaded member causes translational movement of the adjustment member.' 27. Apparatus as claimed in any of Claims 24 to 26 in which the co-operation of the adjustment member with the first and second member Is such that movement of the adjustment member in the f Irst direction to a certain extent causes movement of the second member relative to the first member to a lesser extent.

28. A tool adjustment apparatus substantially as here 1 n descr 1 bed w i th ref erence to, and as shown 1 n Figures 3A and 3B of the accompanying drawings.

29. A rotatable work piece holder comprising a casing Including an Inner portion of hardenable material which has been inserted Into the casing prior to the material hardening.

30. A holder as claimed In Claim 29 In which the casing comprises aluminium.

31. A holder as claimed In Claim 29 or Claim 30 In which the Inner portion is of greater rigidity than the cas 1 ng.

32. A holder as claimed In any of Claims 29 to 31 In which the Inner portion Is adhered or bonded to the cas i ng.

33. A holder as claimed in any of Claims 29 to 32 in which the Inner portion Includes epoxy resin.

34. A holder as claimed In any of Claims 29 to 33 in which the Inner portion Includes reconstituted granite.

35._ A rotatab I e work p I ece ho I der substant I a I I y as herein described with reference to, and as -shown In Figure 4 of the accompanying drawings.

36. A method of forming a rotatable work piece holder comprising Inserting a hardenable material into a casing prior to the material hardening.

37. A method of forming a rotatable work piece holder substantially as herein described with reference to, and as shown in Figure 4 of the accompanying drawing.

38. A work piece which has been refurbished by a method as claimed in any of Claims 1 to 11, or by an apparatus as claimed In any of Claims 12 to 23.

Published 1988 at The Patent Office. State House, 66'71 High Holborn, London WClR 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Maxy Cray, Kent. con. 1/57.