GB2463510A

GB2463510A - Work mat for restricted access environments

Info

Publication number: GB2463510A
Application number: GB0817005A
Authority: GB
Inventors: Dean Carran; Diane Elston; Jan Niklewicz
Original assignee: JNDC Ltd
Current assignee: JNDC Ltd
Priority date: 2008-09-16
Filing date: 2008-09-16
Publication date: 2010-03-17
Also published as: GB0817005D0

Abstract

A work mat 301 comprises a platform 303 having at least one flexible region 310a, and a plurality of base elements 304 fastened to the underside of the platform for supporting the platform. The base elements have a thickness which is determined by the height of projecting members the mat is to be laid over, so that, in use, the platform is raised clear of the projecting members by the base elements (Figure 6). The base elements define channels 309a, b, such that in use the projecting members are accommodated in the channels. The flexible regions of the platform coincide with the channels; the base elements can therefore be folded between a first position, where they lie side-by-side, and a second position, where they are stacked. This allows the work mat to be used in environments with restricted access; for example, aircraft wing sections.

Description

A WORK MAT

BACKGROUND

Technical Field of the Invention

The present invention generally relates to a work mat, and in particular a work mat suited for use in environments with restricted access, and for use on surfaces that have projecting members. The work mat is suitable for use in the construction or the maintenance of bodies that have complex internal structures and is particularly suited for use in, but not limited to, aircraft wing sections, where a skin is fixed to a framework.

io During the construction or maintenance of such bodies a worker needs to get inside the structure to perform operations such as drilling and riveting to fix further elements to the inside or outside of the structure. When inside the structure it is important that the worker is comfortable and has a stable surface to lie on, sit on, or lean against and also upon which to place tools. Some structures are complex inside and have many projecting elements which provide, for example, strength for the overall structure and! or support for an external skin. The projections make it uncomfortable to work in such a structure. Finding a comfortable working position is important in order to perform operations effectively and to eliminate cramps and pains which reduce the amount of time a worker can comfortably spend within the structure. The problem is compounded in situations where access is restricted and also when the space within the structure is restricted. Furthermore, in certain applications it is S...

important to protect the internal structure from damage, which could be caused by S...

the weight of the worker moving against the internal components, or tools laid against the surface, or debris from the workings being dragged across the structure by workers as they move around. It is particularly important to protect the internal * elements of aircraft structures from damage because the smallest scratch can form **S the seed for a stress fracture and hence failure of the component. Wing structures are particularly vulnerable to such damage because their components are highly stressed during operation; elements of the wing structure such as stringers, runners and ribs should therefore be carefully protected in order to reduce the possibility of scratching or otherwise damaging them. However, access to the interior of a wing structure is generally very restricted, which limits the size and shape of protective equipment that can be installed. Furthermore the space for a worker to move around within the wing structure is also restricted which again limits the dimensions of the equipment that can be used to protect internal components.

Description of Related Art

Conventionally, mats of two types are used in the construction of aircraft wing sections in an attempt to protect the wing components and to provide comfort to workers. Both types of mat are limited by the size of the opening through which a worker can gain access to the interior of the wing section. The first type of mat is small and fits between stringers and covers a portion of the internal skin of the wing.

However, the stringers remain exposed and as such are vulnerable to damage and cause discomfort to workers. The second type of mat typically used is a thin foam sheet, which can be rolled up to pass through the access port and unrolled within the wing to be laid across the stringers. However, the stringers can still be felt through the thin foam. Furthermore, the working surface undulates across the stringers which is not a satisfactory surface upon which to rest tools. Furthermore, the foam can trap swarf (fine metal shavings produced when metal is drilled or otherwise worked) which can scratch the wing components.

The present invention seeks to overcome the problems encountered with conventional mats and in particular seeks to overcome the limitations of roll-up mats to provide a work mat capable of supporting a person comfortably while protecting *...

the components of the structure being worked on. * * **** * S**.. * *

*:::: SUMMARY OF THE INVENTION

* 25 The present invention therefore provides a work mat for use with surfaces that have projecting members, the work mat comprising a plafform having at least one flexible region, and a plurality of base elements fastened to the underside of the platform for supporting the platform, wherein the base elements have a thickness determined by the height of the projecting members, such that in use the platform is held above the projecting members by the base elements, and wherein the base elements are positioned on the platform so as to define channels, such that in use the projecting members are accommodated within the channels, and wherein the at least one flexible region of the platform is coincident with the channels thus allowing the base elements to be folded in relation to each other between a first unfolded position where the base elements lie side-by-side, and a second folded position where the base elements are stacked. In this way a worker is provided with a comfortable support without feeling the projections. It is also possible to fold the work mat to a size suitable for passing through the restricted opening of a wing structure.

The channels of the work mat may be of a width that gives a clearance gap between the sides of the base elements and the projections when the work mat is in use.

This reduces the risk that stray swaif or other debris will be dragged across the internal surface of the aircraft causing scratches.

Preferably, three base elements are fastened to the platform and the platform has two flexible regions defined between the base elements and the three base elements may comprise two outer base elements that are half the width of a central base element, such that when the work mat is in the folded position, the two outer base elements are stacked on top of the central base element. This is a convenient configuration for passing through the access port while also offering protection to all of the stringers upon which the work mat rests.

Alternatively, two base elements may be fastened to the platform so that the platform has a single flexible region defined between the base elements. S... * . . S* *

The platform may be made from flexible material such that the at least one flexible *.

region is an integral part of the platform. *. * * **5

The platform may be made from low density foam in order to provide the at least one flexible region and a comfortable working surface. The base elements may be made ***.

: 25 from high density foam blocks to provide a resilient base for the work mat.

S *SS

The base elements may be removably fastened to the platform for convenience, although they are preferably permanently fixed to the platform. The platform and! or the base elements may be covered with a protective layer.

The width of the base elements may be determined by the separation of the projections on a surface. -4..

The surface upon which the work mat is intended to be used may be the interior of an aircraft wing section and the projections are stringers running in parallel set apart at a stringer pitch.

A number of work mats may be placed contiguously in order to tile an area of surface.

In another aspect of the invention, a structure with a surface that has projecting members is provided, where a work mat is fitted such that the channels of the work mat accommodate the projecting members.

In another aspect of the invention, a method of installing a work mat on a surface within a structure is provided, comprising folding the work mat into the second folded position, passing the work mat through an access port in the structure, unfolding the work mat into the first unfolded position, locating the work mat over the projecting members on the surface such that the projecting members are accommodated within the channels of the work mat.

BRIEF DESCRIPTION OF THE DRAWINGS

The forgoing objects described herein may be better understood with reference to the following drawings, which are intended for example purposes only. *..

.. : Figure 1 shows a sectional view of an aircraft wing, within which the present * .** ....20 invention is suited for use. S...

Figure 2a is a cross-sectional view of an aircraft skin supported on T-section stringers as can be found in an aircraft wing such as that illustrated in Figure 1.

*: Figure 2b is a cross-sectional view of an aircraft skin supported on J-section . stringers as can be found in an aircraft wing such as that illustrated in Figure 1.

Figure 3 is a schematic view of a preferred embodiment of the present invention which comprises a work mat in the deployed position.

Figure 4 is a cross-sectional view of the platform of the work mat shown in Figure 3.

Figure 5 is a schematic view of a base element of the work mat shown in Figure 3.

Figure 6 is a cross-sectional view of part of the work mat shown in Figure 3 in position on an internal wing surface with a stringer accommodated within a channel of the work mat.

Figure 7 is a schematic view of an embodiment of the work mat being folded S between the deployed position and the transport position.

Figure 8 is a schematic view of an embodiment of the work mat in the transport position.

Figure 9 is a schematic view of the work mat shown in Figure 8 (transport position), located between stringers in an aircraft wing section.

Figure 10 is a schematic view of the work mat shown in Figure 3 (deployed position), in place with stringers accommodated within the channels of the work mat.

Figure 11 is a schematic view of a series of work mats of the type shown in Figure 3 that have been arranged to tile an area of internal wing surface, such as that shown in Figure 1.

Figure 1 2a is a schematic view of an alternative embodiment of the present invention in the deployed position.

Figure 1 2b is a schematic view of an alternative embodiment of the present invention in the transport position. * * .

Figure 13 is a schematic view of a series of work mats of the type shown in Figure *.

12a that have been arranged to tile an area of internal wing surface, such as that *S* shown in Figure 1. *

* **.** * * * ***

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT S.

S

It will be appreciated that the work mat described herein has numerous applications.

It is particularly suited to applications in environments where access is restricted and! or where the surface to be protected is characterised by members projecting from the surface. Such environments include boat hulls or water tanks or aircraft fuselages. For the purposes of illustration, the description provided below relates to use of the work mat in the construction or subsequent maintenance of the wing sections of large multi-passenger commercial aircraft.

Figure 1 shows a view of a wing section 101, which comprises two wing spars 102 and 102a, an array of ribs 103 fixed to the wing sparslo2 and 102a, stringers 104 fixed to the ribs 103 and a skin 105 fixed to the ribs 103 and stringers 104. While the external surface of the wing section 101 is necessarily smooth and flat, the interior is complex and provides support for the skin 105, and may also house further systems such as fuel tanks (not shown). There are many features projecting from the internal surface of the wing section 101. The most common and, from a worker's to perspective, the most uncomfortable, are the stringers 104. The stringers 104 are set apart at a predetermined distance and run parallel to each other in a direction termed herein as the stringer running direction.

Figure 2a is a cross-sectional view of a series of typical stringers 104 supporting a skin 105. The stringers 104 are of a "T" cross-section and typically project around 7.5cm from the internal surface of the wing section 101, and have a thickness of around 1cm. The stringers 104 are typically set 25cm apart along the length of the ribs 103 -which is a value referred to as the stringer pitch. The stringer pitch is largely constant throughout the wing section 101, although it changes in certain parts. Different aircraft will have different stringer pitches. Figure 2b is a sectional view of another type of stringer with a "J" cross-section. Stringers with a variety of cross-sections may be used in the construction of aircraft wings. The work mat of *. the present invention is intended to be placed over the stringers 104 to protect them and to provide a surface upon which a worker can sit, lie or lean and upon which tools can be laid when not in use. It will be appreciated that the work mat can be used to cover not only stringers but any other member projecting from a surface, particularly a member or set of members that project from a surface and run linearly * across the surface. *** *

During construction or maintenance of a wing section 101 a worker must be able to access the interior of the wing section 101 to perform a variety of actions, for example to fix further components to the wing section 101. A hole in bottom wing skin is therefore used as an access port 106 enabling a worker to get into the wing section 101 and to move around therein. The access port is typically oval in shape and has dimensions typically of 45cm by 25cm. However, the size and shape of the access port 106 will often vary between aircraft types.

Figure 3 shows a schematic view of the present invention in a deployed position, i.e. suitable for lying, sitting or leaning on by a worker. The work mat 301 comprises a s platform 302 which is substantially level and has an upper working surface 303 upon which a worker may rest their tools or themselves. Figure 4 shows a cross sectional view of the platform 302, where it can be seen that the platform 303 is constructed from a core 401 which is made of a low density foam. This material is selected for comfort of the worker and for its ability to flex, for reasons that will be explained below. The foam core 401 may be covered in a flexible protective layer 402 which is preferably a durable PVC coated material. The protective layer 402 is provided so that swarf cannot become embedded in the foam core 401. The protective layer 402 can also be wiped clean after use if necessary. The seams of the protective layer 402 can be either stitched or welded, or any other joining method which reduces the is chances of swarf becoming trapped and also keeps moisture away from the core 401. All of the materials used in the work mat 301 should be fire resistant for safety reasons.

Returning to Figure 3, it can be seen that the platform 302 is supported on its underside by a number of base elements 304a, 304b and 304c. The base elements 304 are made from high density foam blocks and are selected to provide a *: lightweight supporting structure beneath the platform 302. A degree of resilience in this material also gives further comfort to the worker. The base elements 304 may also be covered in a flexib'e protective layer of PVC coated material, for the same *.S reason as the protective layer 402 covering the foam core 401 of the platform 302. *I*.S * *

A single base element is shown in Figure 5. The base elements 304 have an upper **** : platform support surface 501, which is the surface upon which the platform 302 bears. The base elements 304 have a lower contact surface 502, which is the surface of the work mat 301 that rests against the internal surface of the wing section 101. The plane of the lower contact surface 502 is orientated parallel to the platform support surface 501. The distance between the platform support surface 501 and the lower contact surface 502 defines the thickness of the base elements 304. This thickness is selected in dependence on the degree to which the stringers 104 project from the internal surface of the wing section 101. For instance, for a stringer of height 5cm above the internal surface, a base element thickness of approximately 5cm would be required so that the top of the stringer 104 could not be felt by a The base elements 304 have side faces 503 which are parallel to the running direction of the stringers 104. The side faces 503 are separated by a distance that is determined by the separation of the stringers 104, i.e. the stringer pitch, and defines the width of the base elements 304. The central base element 304b has a width approximately equal to the stringer pitch and is intended to sit comfortably between two stringers 104 so that neither of its two side faces 503 are pressing against the stringers 104, and preferably so that there is clearance between the side faces 503 and stringer 104. The clearance given here is to reduce the chance of stray swarf trapped between the work mat 301 and a stringer from scratching the stringers; if swarf or other debris is trapped under pressure, then when the work mat 301 moves, either because the worker deliberately moves the work mat 301 to a new location, or because the worker shifts their position on the work mat 301, then the swarf will be dragged across the surface of the stringer and cause a scratch.

The outer base elements 304a, 304c have a width which is substantially half the width of the central base element 304b. These relative proportions are chosen so that a number of work mats 301 can be tiled together, as described in more detail below. The selected sizes of the base elements 304 also allow the work mat 301 to be folded to fit through restricted openings and for ease of carrying, also described in more detail below. * 0 *0**

The base elements 304 have parallel end faces 504 and the distance between each **.Ss.

end face 504 defines the length of the work mat 301. The length of the work mat *** 301 is limited to what can be comfortably carried by a worker and manipulated within ** the restricted space of the wing section 101. This is typically of the order of 50cm.

However, the length of the work mat 301 could be between less than 10cm and greater than 200cm.

The platform support surfaces 501 of the three base elements 304 are secured to the underside of the platform 302. Velcro (registered trade mark) fastening may be used as a fixing means so that the base elements 304 may be removed from the platform 302, but this is not essential. Indeed in some instances it is preferable to permanently fix the base elements 304 to the platform 302 in order to stabilise the work mat 301 and to reduce the opportunities for swarf and other debris to become trapped. Permanent fixings include plastic welding the base elements 304 to the platform 302 or stitching.

The base elements 304 are fastened to the platform 302 so as to define channels 309a, 309b, which run in the stringer direction along the length of the work mat 301.

The channels 309a, 309b are of a width suitable to receive stringers 104 without the side faces 503 pressing against the stringers 104, and preferably so that there is a io clearance around the stringers 104 in order to minimise contact of the work mat 301 with the stringer faces. This is important for the reasons stated above, i.e. movement of the work mat 301 against the stringers 104 increases the chance that stray swan or other material will scratch or otherwise damage the strInger 104.

Figure 6 shows in detail the clearance around a stringer. Stringer 104 is mounted is upon the skin 105 of the aircraft. The base elements 304a, 304b locate on either side of the stringer 104. The position of the base elements 304a, 304b in relation to the platform 302 is selected to provide adequate clearance but the channel width should also be limited to ensure that the platform 302 is sufficiently supported.

The upper boundary of the channels 309a, 309b are defined by the platform 302.

Since the platform 302 is made of flexible material, two hinge regions 310a, 310b are formed between the base elements 304. The hinge regions 310a, 310b extend V.. S along the length of the platform 302 in the running direction of the stringers 104 to define hinge axes 311a and 311b. The hinge regions 310a, 310b allow the base elements 304 to flex relative to each other, to the extent that the outer base elements * 25 304a, 304c may be folded over the central base element 304b into a configuration * ,. : suitable for carrying or for storage but more particularly for passing through the restricted access port 106 of the wing section 101 and for manoeuvring within the wing section 101. This position will hereafter be referred to as the transport position.

A line of stitching or welding may be applied along the hinge axes 311a, 311b in order to better define the hinge region and allow more flexibility and more positive folding of the work mat 301. The foam core 401 may be divided into sections along the hinge axes 311a, 311b for the same reason.

Figure 6 also shows a fastening means 601 used to secure the base elements 304 to the platform 302.

Figure 7 shows the work mat 301 being converted from the deployed position to the transport position and Figure 8 shows the work mat 301 in the transport position.

The work mat illustrated in Figure 8 does not have a closing means, but a clasp or strap could be used to secure the work mat 301 in the transport position.

Figure 8 shows a work mat 301 in relation to an access port 106. As noted above, the access port 106 is approximately 45cm wide, which is of the order of the stringer pitch dimension. In the deployed position, the width of the work mat 301 is io approximately twice the stringer pitch dimension and therefore cannot fit through the access port 106. However, the width of the work mat 301 when in the transport position is defined by the width of the central base element 304b because the outer base elements 304a, 304c are folded into a position on top of the central base element 304b. Since the width of the central base element 304b is slightly less than is the stringer pitch it is of a width that will fit through the access port 106. The thickness of the work mat 301 in the transport position is approximately twice the height of the stringers plus twice the thickness of the platform 302, i.e. around 18cm and therefore the cross-section of the work mat 301 has clearance to fit through this particular access port 106.

Figures 9 and 10 show how the work mat 301 is deployed in order to protect stringers 104. In Figure 9 the work mat 301 is shown in the transport position (or folded position), where the outer base elements 304a, 304c are stacked on top of the central base element 304b. The central base element 304b is placed between two stringers 104. Figure 10 shows the work mat 301 in the deployed position, where the outer base elements 304a, 304c have been folded out so that platform 302 is : substantially flat and level, ready to be used by a worker and offering protection to the stringers 104.

Figure 11 shows how a number of work mats 301 can be placed contiguously to provide a larger working area. Any number of work mats 301 can be tiled in this way, provided that the stringer pitch width remains constant.

Work mats 301 may be adapted for use on surfaces having a range of projections.

Different projection profiles are accommodated by making work mats with appropriate gap size between the base elements 304. Different projection projections heights are accommodated by making work mats with appropriately thick base elements 304. Different stringer pitches are accommodated by making work mats with base element widths of suitable size. The work mats may be colour coded to identify mats for application in different areas of wing section or different types of aircraft wing sections which may be produced within the same facility.

A further variation of the work mat is where two base element blocks are provided with a single flexible region, as illustrated in deployed position in Figure 12a and transport position in Figure 1 2b. Figure 13 shows a number of the two base element variations tiled together.

It is to be understood that various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those is skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown and such modifications and variations also fall within the spirit and scope of the appended claims. *.. * ** ** * * .S. * * *** *.* * I S...

I S.. * a **** * a.

SI S a *a.

Claims

CLAIMS1. A work mat for use with surfaces that have projecting members, comprising: a platform having at least one flexible region, and a plurality of base elements fastened to the underside of the platform for supporting the platform, wherein the base elements have a thickness determined by the height of the projecting members, such that in use the platform is held above the projecting members by the base elements, and wherein the base elements are positioned on the platform so as to define channels, such that in use the projecting members are accommodated within the channels, and wherein the at least one flexible region of the platform is coincident with the channels thus allowing the base elements to be folded in relation to each other between a first unfolded position where the base elements lie side-by-side, and a second folded is position where the base elements are stacked.
2. A work mat as claimed in claim, wherein the channels are of a width that gives a clearance gap between the sides of the base elements and the projections when the work mat is in use.
3. A work mat as claimed in claim 1 or 2, wherein three base elements are fastened to the platform and the platform has two flexible regions defined between the base elements.
4. A work mat as claimed in claim 3, wherein the three base elements comprise :. a central base element and two outer base elements, and wherein the two outerSbase elements are half the width of the central base element, such that when the work mat is in the folded position, the two outer base elements are stacked on top of *5*S the central base element.S*.S...

*
5. A work mat as claimed in claim 1 or 2, wherein two base elements are S..' fastened to the platform and the platform has a single flexible region defined between the base elements.
6. A work mat as claimed in any preceding claim, wherein the platform is made from flexible material such that the at least one flexible region is an integral part of the platform.
7. A work mat as claimed in any preceding claim, wherein the platform is made from low density foam in order to provide the at least one flexible region and a comfortable working surface.
8. A work mat as claimed in any preceding claim, wherein the base elements are made from high density foam blocks to provide a resilient base for the work mat.
9. A work mat as claimed in any preceding claim, wherein the base elements are io permanently fastened to the platform.
10. A work mat as claimed in claims 1 to 8, wherein the base elements are removably fastened to the platform.
11. A work mat as claimed in any preceding claim, wherein the platform is covered with a protective layer.
12. A work mat as claimed in any preceding claim, wherein the base elements are covered with a protective layer.
13. A work mat as claimed in any preceding claim, wherein the cross-section of the work mat in the folded position is such as to allow it to be passed through a restricted opening.
14. A work mat as claimed in any preceding claim, wherein the width of the base elements is determined by the separation of the projections on a surface. S...
15. A work mat as claimed in any preceding claim, wherein the surface upon which the work mat is intended to be used is the interior of an aircraft wing section and the projections are stringers running in parallel set apart at a stringer pitch.
16. A work mat as claimed in any preceding claim, wherein a plurality of work : mats are placed contiguously in order to tile an area of surface.S
17. A structure with a surface that has projecting members, said structure having a work mat of the type claimed in any one of claims 1 to 15 fitted such that the channels of the work mat accommodate the projecting members.
18. A method of installing a work mat of the type claimed in any one of claims I to 15 on a surface within a structure, comprising; folding the work mat into the second folded position, passing the work mat through an access port in the structure, unfolding the work mat into the first unfolded position, locating the work mat over the projecting members on the surface such that the projecting members are accommodated within the channe's of the work mat.
19. A work mat substantially as described above and illustrated in the accompanying figures. S... * * * S. S *... * S *S.S *SSS * * *...SS..... * S S... * S S S. *S S..I