WO2016176746A1

WO2016176746A1 - Manufacture of a tactile indicator plate or tile

Info

Publication number: WO2016176746A1
Application number: PCT/AU2016/050341
Authority: WO
Inventors: Daniel Dedomenico
Original assignee: Cta Australia Pty Ltd
Priority date: 2015-05-07
Filing date: 2016-05-06
Publication date: 2016-11-10

Abstract

There is disclosed a method of manufacturing a tactile ground surface indicator plate or tile having a base and at least one indicator which protrudes upwardly from the base, the method comprising compressing a plate between punch and die sections of a pressing apparatus, the punch section comprising at least one punch and the die section comprising at least one cavity, whereby the or each punch forces a portion of the plate into a respective said cavity, thereby plastically deforming it to form a protuberance, the or each indicator of the indicator plate or tile comprising a respective said protuberance or a portion which derives from that protuberance.

Description

MANUFACTURE OF A TACTILE INDICATOR PLATE OR TILE

The present invention relates to a method of manufacturing a tactile indicator plate or tile, and the plate or tile formed via the method. Preferred embodiments of the invention provide an integrated tactile ground surface indicator, which may comply with Australian Standard 1428 - Design for access and mobility ("AS 1428"), which comprises a series of tactile ground surface indicators in a defined pattern of the same colour and material as the underlying surface. Tactile ground surface indicators comprise protuberances which are fixed over walking surfaces, including in particular footpaths, stairs and platforms, principally to warn blind and vision-impaired pedestrians of a hazard ahead and/or to provide them with directional orientation information. Such protuberances can be installed one -by-one, by anchoring each to the ground, typically each via a projection, such as a stem, which projects downwardly from the protuberance and is fixed in a cavity in the ground, or arranged in arrays on the upper surface of a plate or tile, which plate or tile is secured, e.g. by adhesive/cement and/or fasteners, to the ground. The latter kind can be installed more easily and rapidly, and are subject to far less stringent luminance contrast requirements under AS 1428, which prescribes, for an integrated indicator, that there be a luminance contrast between that indicator and the substratum (i.e. the surface of the ground in/over which the indicator is installed), of 30% and, for a discrete indicator, that there be a minimum luminance contrast, between that indicator and the substratum, of 45% where the indicator is a coloured tactile stud and 60% where the indicator is polychromatic.

It is desirable to be able to form tactile indicator plate or tiles simply and rapidly.

According to a first aspect of the present invention, there is provided a method of manufacturing a tactile ground surface indicator plate or tile having a base and at least one indicator which protrudes upwardly from the base, the method comprising compressing a plate between punch and die sections of a pressing apparatus, the punch section comprising at least one punch and the die section comprising at least one cavity, whereby the or each punch forces a portion of the plate into a respective said cavity, thereby plastically deforming it to form a protuberance, the or each indicator of the indicator plate or tile comprising a respective said protuberance or a portion which derives from that protuberance.

In a preferred embodiment of the invention, base is defined by or includes an undeformed portion of the plate.

In a preferred embodiment of the invention, the punch section comprises plural said punches which are spaced apart and the die section comprises plural said cavities which are spaced apart, whereby each punch forces a respective said portion of the plate into a respective said cavity to form a respective said protuberance and the indicator plate or tile thus has plural said indicators. Preferably, the portions are forced by the punches into the cavities simultaneously. In an alternative embodiment of the invention, the punch section has only one said punch and the die section has only one said hole, whereby the indicator plate or tile has only one said indicator. Preferably, creation of the or each indicator includes forming an exterior configuration of that indicator into a respective said protuberance.

Preferably, formation of the exterior configuration into the or each protuberance is effected by plastically deforming the portion(s) of the plate. Preferably, the or each portion of the plate is, when the plate is compressed, forced against a respective patterned portion of the die such that a said exterior configuration is formed into the or each protuberance. Preferably, the or each die patterned portion is arranged at a closed end of a respective said cavity, against which end said portion is forced. Preferably, the or each portion of the plate is, when the plate is compressed, forced against a respective patterned portion of the punch such that a said exterior configuration is formed into each protuberance. In a preferred embodiment of the invention, the patterned portion of the or each punch is arranged at an extent of that punch which is closest to a closed end of the cavity into which it forces a respective said portion of the plate. Preferably, in that embodiment, the or each said portion of the plate is forced against the closed end of a respective said cavity when the plate is compressed.

Preferably, the patterned portions of the die and punch(es) are complementarily configured, the or each patterned portion of the die being substantially the inverse of the patterned portion of the punch with which it compresses a respective said portion of the plate.

In an embodiment of the invention, the or each exterior configuration is formed after compression of the plate between the punch and die sections to form the protuberance(s). Preferably, in that embodiment, the or each exterior configuration is formed by compressing a wall of the protuberance, into which that configuration is formed, between opposed members forming a respective opposed member pair, at least one of which members is configured with a patterned portion against which said wall is forced. Preferably, in the or each opposed member pair, the member which contacts an exterior side of the wall compressed between the opposed members comprises a said patterned portion. Preferably, in the or each opposed member pair, the member which contacts an interior side of the wall compressed between the opposed members comprises a said patterned portion. Preferably, the patterned portions of the members in the or each opposed member pair are complementarily patterned, each patterned portion of one member in that pair being substantially the inverse of the patterned portion in the other member of that pair. Preferably, the opposed members form part of a pressing apparatus which is operated to effect simultaneous compression of the wall of the or each protuberance between opposed members in a respective said opposed member pair, whereby the or each exterior configuration is formed. Formation of the exterior configurations may be effected, additionally or alternatively, by machining said portions of the plate. The machining may, for example, comprise milling. Preferably, the or each exterior configuration is formed into a top wall of a respective said protuberance/indicator.

Preferably, the or each exterior configuration comprises a surface pattern.

Preferably, the or each exterior configuration confers anti-slip characteristics to the indicator plate or tile.

Preferably, the or each exterior configuration is formed at a top end of a respective said indicator.

Preferably, the plate is metal. Preferably, the metal is steel. Preferably, the steel is stainless steel. Alternatively, the metal may, for example, be brass or copper, which may be suitable where the indicator plate or tile is to be installed at a heritage-listed building location, or aluminium, where it is to be particularly lightweight.

Alternatively, the plate may be plastic. The plastic may comprise polyurethane, which is highly wear-resistant. Alternatively or additionally, it may comprise silicone, polyvinyl chloride (PVC) and/or polyethylene (either low-density (LDPE) or high density (HDPE)). In an alternative embodiment of the invention, the plate may have a coarse surface whereby the protuberances have anti-slip characteristics.

Preferably, a distal end of the or each punch is received in the cavity into which it forces a respective said portion of the plate when plastically deforming that portion to form a respective said protuberance.

Preferably, a/the distal end of the or each punch and the cavity into which it forces a respective said portion of the plate when plastically deforming that portion have complementary configurations, whereby the or each protrusion has a shape corresponding to those configurations. In a preferred embodiment of the invention, said complementary configurations are substantially frustoconical or truncated cone-shaped.

In a preferred embodiment of the invention, said complementary configurations are substantially frustospherical.

In a preferred embodiment of the invention, the configuration of the end of the or each punch is substantially dome-shaped and the configuration of the or each cavity is substantially bowl-shaped.

In a preferred embodiment of the invention, the configuration of the end of the or each punch is substantially rib-shaped and the configuration of the or each cavity is substantially slot-shaped or elongate bowl-shaped. In a preferred embodiment of the invention, the or each protuberance is formed in the shape of a truncated cone, dome or rib.

According to a second aspect of the present invention, there is provided the tactile ground surface indicator plate or tile formed by said method.

According to a third aspect of the present invention, there is provided said pressing apparatus.

According to a fourth aspect of the present invention, there is provided the pressing apparatus of which said opposed members form a part.

The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figure 1A is a perspective view of a tactile ground surface indicator plate or tile formed via a method embodying the present invention; Figure IB is a perspective view of a blank from which the tactile ground surface indicator plate or tile is formed; Figure 1C is a perspective view showing the configuration of an indicator element of the indicator plate or tile;

Figure 2 is a perspective view showing punch and die sections of a press used in the fabrication of the indicator plate or tile according to a first embodiment of the invention;

Figure 3A is a perspective view showing the configuration of a punch in the punch section of the press; Figure 3B is a perspective view showing the configuration of a die in the die section of the press;

Figures 4A and 4B are schematic views showing operation of the press to form the indicator plate or tile in accordance with the first embodiment;

Figure 5 is a perspective view showing punch and die sections of a press used to form protuberances in the first of two stages in the fabrication of the indicator plate or tile according to a second embodiment of the invention; Figure 6A is a perspective view showing the configuration of a punch in the punch section of the press shown in Figure 5;

Figure 6B is a perspective view showing the configuration of a die in the die section of the press shown in Figure 5; Figure 6C is a perspective view showing an intermediate product resulting from operation of the press shown in Figure 5;

Figure 7 is a perspective view showing opposed punch and die sections of a press operable to complete the manufacture of the indicator plate or tile in the second stage in the fabrication of the indicator plate or tile according to the second embodiment;

Figure 8A is a perspective view showing the configuration of a punch in the punch section of the press shown in Figure 7;

Figure 8B is a perspective view showing one of plural arrangements of apertures or voids in a die plate in the die section of the press shown in Figure 7, each arrangement being arranged to cooperate with a respective punch in the punch section of that press; Figure 9A are schematic views showing operation of the press of Figure 7 in the second manufacturing stage, to form the indicator plate or tile;

Figure 10A is a perspective view of an alternative tactile ground surface indicator plate or tile formed via a method embodying the present invention;

Figure 1 OB is a perspective view showing the configuration of an indicator element of the indicator plate or tile shown in Figure 10A;

Figure IOC is a perspective view showing the configuration of a punch in a punch section of a press which corresponds to that shown in Figure 7 but is configured specifically for manufacture of the indicator plate or tile shown in Figure 10A; and

Figure 10D is a perspective view showing one of plural arrangements of apertures or voids in the die plate of the die section of the aforementioned corresponding press, each arrangement being arranged to cooperate with a respective punch in the punch section of that press. The invention is embodied in simple and rapid methods of manufacturing a tactile ground surface indicator plate or tile 1 as shown in Figure 1A. The plate or tile 1 comprises a body 3 and, projecting upwardly from the body 3, indicator elements or indicators 5 arranged in an array. Referring to Figure 1C, each indicator 5 is integrally formed with the body 3 and configured with a gripping pattern 7 on an exterior side of a top wall 9 thereof. Each element 5 is generally frustoconical, though other element shapes are possible, including, for example, hemispherical or dome shapes or elongate rib or bar shapes (the or each rib/bar shape possibly defining a directional rib or bar), without departure from the invention.

The indicator plate or tile 1 is formed from a malleable plate 10, shown in Figure IB. The plate 10 can be metal, such as steel (preferably stainless steel), brass, copper and/or aluminium, or suitably malleable plastic, such as polyurethane, silicone, polyvinyl chloride (P VC ) and/or polyethylene .

Referring to Figures 2, 3 A, 3B, 4A and 4B, fabrication of the indicator tile or plate 1 from the plate 10 via a method according to a first embodiment of the invention consists of a single pressing operation, which is effected using a stamping press 20. As shown in Figure 2, the press 20 includes a die section 30, comprising a body 31 and an array of cavities 32 which open through a flat upper surface 34 of the body 30, and a punch section 40, opposed to the die section 30 and comprising a body 41 and an array of punches 42 each of which projects from the body 41 and is concentrically aligned with a respective cavity 32 (the sections 30 and 40 being shown in Figure 2 as divergent only for the purposes of revealing their configurations).

Referring to Figure 3A, each punch 42 has a substantially frustoconical tip 44 and is configured with protrusions 46 arranged on a downwardly facing surface 48 of the punch 42 at a leading end of a body of the punch. Referring to Figure 3B, each of the cavities 32 is frustoconical, comprising a tapered side face 36 and a flat, upwardly facing surface 37 at its base. An arrangement of apertures or voids 38 opens through the surface 37. The arrangement of voids 38 opening into each cavity 32 is complementary to and aligned with the arrangement of protrusions 46 of the punch 42 which is concentrically aligned with that cavity, so that the pattern defined by the voids 38 is substantially the inverse of the pattern defined by the protrusions 46, each void 38 being cross sectionally slightly larger than a respective protrusion 46 with which it aligns. Each tip 44 is sufficiently small cross-sectionally that it can fit within the respective cavity 32.

Referring to Figure 4A, fabrication of the indicator plate or tile 1 commences with placing the plate 10 on the die section upper surface 34. Preferably, the die section includes a peripheral wall (not shown) which surrounds the plate 10 when placed on the upper surface 34, locating the plate 10 and restraining it from movement in the plane of the surface 34. The press 20 is then operated to force the punch section downwardly whereby the tips 44 of the punches 42 are urged against portions of the plate 10, forcing them into respective cavities 32. Each tip 44 is cross-sectionally narrow enough, and the plate 10 thin enough, that that tip 44 is received within the respective cavity 32 when it forces the respective plate portion into the cavity. Owing to the punch tips 44 and respective cavities 32 being complementarily shaped, the deformation of the plate portions results in the formation of an array of correspondingly shaped (in the present embodiment, frustoconical) protuberances. The stroke of each punch 42 is sufficient that central portions of the deformed plate portions are compressed between the punch tip surfaces 48 and the bottom surfaces 37 of the cavities 32, whereby the protrusions 46 force material in the respective central portion into the respective voids 38, giving rise to an arrangement of square/diamond-shaped protrusions, defining the gripping pattern 7, on a top face of the respective protuberance, each protuberance thus defining a respective indicator element 5. Referring to Figure 4B, the punches 42 are then retracted and the thus-formed indicator plate or tile 1 is removed from the die section 30.

In the following description of further embodiments of the invention, and in the associated drawings, like reference numerals are used to refer to like features, and an apostrophe is used together with any such reference numeral where the feature in question has been varied. Fabrication of the indicator plate or tile 1 in accordance with a second embodiment of the invention will now be described referring to Figures 5, 6A, 6B, 6C, 7, 8A, 8B, 9A and 9B. Unlike the manufacturing method of the first embodiment, which comprises a single pressing operation, the manufacturing method of the second embodiment comprises two pressing stages, the first resulting in formation of protuberances having smooth exterior faces, which define the general shape of the indicator elements 5, and the second resulting in formation of the protrusions defining the grip pattern 7. The first pressing stage involves the use of a press 20', shown in Figure 5, which is identical to the press 20 except that, with reference to Figures 6A and 6B, the tips 44' of the punches 42' do not include protrusions and die section 30 does not include voids, whereby the top wall 9' each of the protuberances 5' formed in the first pressing stage has an upper face which is smooth throughout in an intermediate piece 10' thus formed, as shown in Figure 6C.

Referring to Figures 7 and 9A, the intermediate piece 10' is placed in a stamping press 60 which includes a punching section 70 and a die section 80 opposed to and above the punching section 70. (The sections 60 and 70 are shown in Figure 7 as divergent only for the purposes of revealing their configurations.) The punching section 70, referring to Figures 7 and 8A, comprises a body 71 and an array of punches 72 each of which projects upwardly from the body 71 and includes a substantially frustoconical tip 74 configured with protrusions 76 arranged on an upwardly facing surface 78 thereof. The die section 80, referring to Figures 7 and 8B, comprises a body 81 having a downwardly facing surface 87 and configured with die portions 86 each of which comprises an arrangement of voids 88 opening through the surface 87. Each arrangement of voids 88 is complementary to and aligned with the arrangement of protrusions 76 on a respective one of the punches, so that the pattern defined by the voids 88 is substantially the inverse of the pattern defined by the protrusions 76, each void 88 being cross-sectionally slightly larger than a respective protrusion 76 with which it aligns. The sections 70 and 80 as shown in Figure 7 are divergent only for the purposes of revealing their configurations. Referring to Figure 9A, the intermediate piece 10' is placed on the punching section 70 such that the punch tips 74 are concentrically received into hollow interiors of the protuberances 5' . Referring to Figure 9 A, the die section 80 is then urged downwardly such that the top walls 9' of the protuberances 5' are compressed between the punches 72 and die portions 86, whereby the protrusions 76 force material in the top wall 9' into the voids 88, giving rise to the arrangement of square/diamond- shaped protrusions defining the gripping pattern 7. The die section 80 is thereafter retracted and the thus-formed indicator plate or tile 1 removed from the punching section 70.

As mentioned previously, each indicator element can, without departure from the invention, be configured in the form of an elongate rib or bar, and may thereby define a directional rib/bar. Shown in Figure 10A is a tactile ground surface indicator , also embodying the invention, which includes such elements. The plate or tile is formed in exactly the same manner as the plate/tile 1, comprising a body 3, and, projecting upwardly from the body 3, indicator elements or indicators 5', integrally formed with the body 3 and configured with a gripping pattern 7 on an exterior side of a top wall 9 thereof. The indicator elements or indicators 5' are configured in the form of parallel respective ribs or bars and, to that end, referring to Figures IOC and 10D, the punch section 40' and die section 30' of the stamping press used to form the plate or tile are appropriately configured. More particularly, the punches 42', configured with protrusions 46, are elongated, rather than circular, in cross section, as is each of the respective cavities 32', of the die section 30', aligned with those punches 42' . In this embodiment, the configuration of the end of each punch 42' is substantially rib-shaped in the configuration of the or each cavity 32' is substantially slot-shaped or elongate bowl-shaped. The plate or tile can be varied in numerous ways without departure from the invention; for example, instead of comprising one row of side-by-side elongate indicator elements or indicators 5', as shown in Figure 10A, it may comprise plural, e.g. two, rows of such elements/indicators, each element/indicator in one row being aligned, in end-to-end relation, with a respective element/indicator in the or each other row Of course, the plate or tile 1 ' can, instead, be manufactured via a method which comprises two pressing stages, consistent with fabrication in accordance with the second embodiment described previously, the first resulting in formation of protuberances having smooth exterior faces, which define a general shape of the indicator elements 5' and the second resulting in the formation of the protrusions defined in the grip pattern 7.

In the examples shown, each of the punch protrusions and the voids complementary to it are diamond- shaped/square or rectangular, though it will be appreciated that they may have other shapes - for example, other regular shapes, such as circles or ovals, and irregular shapes, which may, for example, define the trade mark of a manufacturer or supplier of the indicator plate or tile.

In another embodiment of the invention, the indicator plate or tile can be formed by subjecting the plate blank to only a single pressing operation using the press, the resulting indicator plate or tile then not having a surface pattern which is pressed into it. Such an embodiment may be appropriate where the indicator elements need only have smooth exterior faces or where the blank 10 has a coarse surface which will define the exterior surface of the indicator plate or tile, which surface may, for example, have been created by knurling or result from the plate material being grainy.

Alternatively, formation of the gripping pattern, following pressing using the press 20' or the press corresponding to it for forming the elongate protuberances, may be effected by a machining operation, such as milling. In another embodiment, press-formed exterior configurations of the indicators of the indicator plate or tile may be such that each of the protuberances has, on the exterior of its top wall, a shallow upwardly opening recess, that may (for example) be bounded by a peripheral, upwardly projecting lip, which recess can fixedly receive an infill or insert, which infill/insert may be, for example, metal, plastic or another material, e.g. carborundum (silicon carbide), which can self -bond to the protuberance or be bonded to it via adhesive, in which case the or each indicator/indicator element in the indicator plate or tile comprises the respective protuberance and infill/insert received in the recess thereof. It will thus be appreciated that an exterior configuration of the or each indicator/indicator element formed in a method embodying the invention need not be one which defines a gripping pattern.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method of manufacturing a tactile ground surface indicator plate or tile having a base and at least one indicator which protrudes upwardly from the base, the method comprising compressing a plate between punch and die sections of a pressing apparatus, the punch section comprising at least one punch and the die section comprising at least one cavity, whereby the or each punch forces a portion of the plate into a respective said cavity, thereby plastically deforming it to form a protuberance, the or each indicator of the indicator plate or tile comprising a respective said protuberance or a portion which derives from that protuberance.

2. A method according to any one of the preceding claims, wherein the base comprises an undeformed portion of the plate.

3. A method according to claim 1 or 2, wherein the punch section comprises plural said punches which are spaced apart and the die section comprises plural said cavities which are spaced apart, whereby each punch forces a respective said portion of the plate into a respective said cavity to form a respective said protuberance.

4. A method according to any one of the preceding claims, wherein creation of the or each indicator includes forming an exterior configuration of that indicator into a respective said protuberance.

5. A method according to claim 4, wherein formation of the exterior configuration into the or each protuberance is effected by plastically deforming the portion(s) of the plate.

6. A method according to claim 5, wherein the or each portion of the plate is, when the plate is compressed, forced against a respective patterned portion of the die such that a said exterior configuration is formed into the or each protuberance.

7. A method according to claim 6, wherein the or each die patterned portion is arranged at a closed end of a respective said cavity, against which end said portion is forced.

8. A method according to any one of claims 4 to 7, wherein the or each portion of the plate is, when the plate is compressed, forced against a respective patterned portion of the punch such that a said exterior configuration is formed into each protuberance.

9. A method according to claim 8, wherein the patterned portion of the or each punch is arranged at an extent of that punch which is closest to a closed end of the cavity into which it forces a respective said portion of the plate.

10. A method according to claim 8 or 9 as dependent from claim 6 or 7, wherein the patterned portions of the die and punch(es) are complementarily configured, the or each patterned portion of the die being substantially the inverse of the patterned portion of the punch with which it compresses a respective said portion of the plate.

11. A method according to claim 4 or 5, wherein the or each exterior configuration is formed after compression of the plate between the punch and die sections to form the protuberance(s).

12. A method according to claim 11 as appended to claim 5, wherein the or each exterior configuration is formed by compressing a wall of the protuberance, into which that configuration is formed, between opposed members forming a respective opposed member pair, at least one of which members is configured with a patterned portion against which said wall is forced.

13. A method according to claim 12, wherein, in the or each opposed member pair, the member which contacts an exterior side of the wall compressed between the opposed members comprises a said patterned portion.

14. A method according to claim 12 or 13, wherein, in the or each opposed member pair, the member which contacts an interior side of the wall compressed between the opposed members comprises a said patterned portion.

15. A method according to claim 14 as appended to claim 13, wherein the patterned portions of the members in the or each opposed member pair are complementarily patterned, each patterned portion of one member in that pair being substantially the inverse of the patterned portion in the other member of that pair.

16. A method according to any one of claims 12 to 15, wherein the opposed members form part of a pressing apparatus which is operated to effect simultaneous compression of the wall of the or each protuberance between opposed members in a respective said opposed member pair, whereby the or each exterior configuration is formed.

17. A method according to any one of claims 4 to 16, wherein the or each exterior configuration is formed into a top wall of a respective said protuberance.

18. A method according to any one of claims 4 to 17, wherein the or each exterior configuration comprises a surface pattern.

19. A method according to claim 18, wherein the or each exterior configuration confers anti-slip characteristics to the indicator plate or tile.

20. A method according to claim 19, wherein the or each exterior configuration is formed at a top end of a respective said indicator.

21. A method according to any one of the preceding claims, wherein the plate is metal.

22. A method according to claim 21, wherein the metal is steel.

23. A method according to claim 22, wherein the steel is stainless steel.

24. A method according to claim 3 or any one of claims 4 to 23 as dependent therefrom, wherein the portions are forced by the punches into the cavities simultaneously.

25. A method according to any one of the preceding claims, wherein a distal end of the or each punch is received in the cavity into which it forces a respective said portion of the plate when plastically deforming that portion to form a respective said protuberance.

26. A method according to any one of the preceding claims, wherein a distal end of the or each punch and the cavity into which it forces a respective said portion of the plate when plastically deforming that portion have complementary configurations, whereby the or each protrusion has a shape corresponding to those configurations.

27. A method according to claim 26, wherein said complementary configurations are substantially frustoconical or truncated cone-shaped.

28. A method according to claim 26, wherein said complementary configurations are substantially frustospherical.

29. A method according to claim 26, wherein the configuration of the end of the or each punch is substantially dome-shaped and the configuration of the or each cavity is substantially bowl-shaped.

30. A method according to claim 26, wherein the configuration of the end of the or each punch is substantially rib-shaped and the configuration of the or each cavity is substantially slot-shaped or elongate bowl-shaped.

31. A method according to any one of claims 1 to 26, wherein the or each protuberance is formed in the shape of a truncated cone, dome or rib.

32. The tactile ground surface indicator plate or tile formed by a method according to any one of the preceding claims.

33. The pressing apparatus for effecting the compression of the plate in a method according to any one of claims 1 to 31.

34. The pressing apparatus, of which said opposed members in the method according claim 16 or any one of claims 17 to 31 as dependent therefrom form a part.