WO2005012834A1

WO2005012834A1 - Distance measuring target

Info

Publication number: WO2005012834A1
Application number: PCT/GB2004/003278
Authority: WO
Inventors: Michael Angelo Calienda
Original assignee: Michael Angelo Calienda
Priority date: 2003-07-30
Filing date: 2004-07-28
Publication date: 2005-02-10
Also published as: GB2419669B; GB2419669A; GB0601665D0

Abstract

A combination distance measuring target comprising a flag portion (1, 1 a, 1b) including a target area (4, 4a), the flag portion being adapted to be releasably secured to a base portion (2, 2a, 2b), the base portion being adapted to be secured to a fixed base structure, such as the rail of a railway track.

Description

DISTANCE MEASURING TARGET

This invention relates to Electric Distance Measurement (EDM) laser targets such as those used to measure positional movements in structures such as railway lines where multiple targets are permanently or semi-permanently attached to the rail at regular intervals and can thereafter be used to reflect incoming laser radiation from an EDM laser device placed at a respective Permanent Ground Mark (PGM) established, typically, by the use of a Global Positioning System (GPS) . A known EDM laser target consists of a foldable sheet of aluminium haying on a portion thereof a small area of reflective material with a cross-hair gun site onto which a laser beam may be directed and reflected in order to take the measurement of the position of the target. The target itself is folded from an initially flat shape to a part corrugated or ribbed shape in which the reflective material becomes raised relative to the respective ends of the sheet or "feet", which are then stuck to the web portion of the rail by e.g. epoxy resin after the orientation of the reflective portion relative to the laser at the PGM has been established. This initial setting up of the EDM laser target can be time consuming and costly in terms of manpower, requiring the presence of safety personnel to act as lookouts for unexpected railway rolling stock, as well as requiring technicians at the PGM to operate the EDM laser and record its results and at the target end to ensure correct orientation and alignment of the target before it is finally glued to the foot or side web of the rail. Accordingly, a number of disadvantages ensue, the first of which being that because such targets necessarily have to be made of bendable material to adjust to a variety of different orientations and angular positions of the reflective material relative to the EDM laser, when they are finally set in place any, later, movement of the target, such as by accidentally being stepped upon or through damage caused by e.g. vandals, requires the entire target to be removed and repositioned. Hence, even though the target itself is relatively inexpensive the consequences are significant in terms of the number of personnel required for such an operation. The overall cost of replacing/repositioning such conventional targets is therefore disproportionate to the cost of the target itself. The present invention is derived from the realisation that it would be preferable to have an EDM target which includes a detachable base plate such that when the base plate and target is fitted to e.g. the foot or side of a rail the target itself can be removed and replaced without the need for the base plate to be repositioned if, say, the target is damaged following original installation at a required position and orientation. According to the invention there is provided a combination target for distance measuring comprising a flag portion including a target area, the flag portion being adapted to be releasably secured to a base portion, the base portion being adapted to be secured to a fixed base structure, such as the rail of a railway track. Conveniently, the flag portion is in the form of a stem, on the upper end of which is the target area and on the lower end of which is a spigot adapted to be received within a correspondingly shaped slot . or aperture within the base portion. The base portion may conveniently include formations, such as holes or slots to provide a key or anchor for e.g. adhesive to be used to secure the base portion to a fixed structure such as the foot or side web of a rail. The flag portion may also conveniently include a marker area below the target area to allow for reference information to be affixed thereto, such as an indication that a Temporary Bench Mark (TBM) reading is being or has been taken at the point where the target area is disposed above the base portion. Conveniently, the target area may include a reflective flag prism material such as M3 LDP 7391 providing high levels of reflectivity, which flag prism material may also conveniently be provided with pre-printed cross hairs in order to facilitate accurate readings. Further, compass points may be provided around the target area to enable the use of manual targeting, such as through the use of laser levelling devices. Such compass points may conveniently project out of the target area, each being at 90 degrees to other such compass points. The stem portion may conveniently include one or more waisted regions permitting the flag to be bent and, through the use of a material having low hysterisis, thereby permitting the angular orientation of the flag relative to the base portion to be adjusted relative to its original shape and, thereafter, to remain in such adjusted position. In a preferred embodiment of the invention, the stem portion is circular in cross section so as to offer little resistance to wind. The stem portion may also include an elbow or stepped portion where the base portion is intended to be affixed to an inclined or vertical surface, such as on one side of the central web of a portion of railway track to thereby permit the flag portion to be still orientated generally vertically prior to final adjustment. Conveniently, the end of the stem portion remote from the flag portion is provided with formations and/or recesses engageable with corresponding formations and/or recesses in the base portion permitting the stem to be angularly adjustable about its major axis relative to the base portion, such as by the use of polygonally shaped formations and recesses which inter-engage and which may be releasably secured in position by e.g. a spigot extending from the stem portion into a correspondingly shaped aperture within the base portion by means of e.g. a snap fit. In such an arrangement, markers may conveniently be positioned on or in the base indicating angular orientation of a reference part of the stem or flag portion with the base such that if, say, 12 different positions are available at equi-spaced intervals about the major axis of the stem each such interval therefore indicates a 30° difference from adjacent reference points. In a preferred embodiment of the invention, splines are used to provide for greater adjustability, such as by the use of 36 splines on the spigot extending from the stem portion engagable with 36 grooves in the base portion, thereby allowing for radial adjustment at 10° increments. In a preferred embodiment of the invention, the stem portion is made of relatively hard plastics material and includes a waist region designed to allow the flag portion to snap off to minimise the risk of the flag portion becoming a tripping hazard. Where the stem portion is made of such relatively rigid plastics material it will be appreciated that such is not readily bendable so as to allow tilting of the flag portion in a required direction and in such circumstances wedge-shaped shims may be placed below the base portion to provide for such tilting adjustment and such shims may even be provided with projections or recesses engageable with corresponding projections or recesses on or in the base portion by which the latter may be releasably engageable therewith following or before fixing of the former to e.g. the web or foot of a rail. The base portion may also be provided with a cap for closing the aperture into which the stem portion of the flag portion is otherwise insertable such that after initial set up and marking of radial orientation of the stem portion relative to the base portion the flag portion may be removed and replaced with a cap to thereby allow the flag portion to be used elsewhere and for it to be reinserted onto or into the base portion at a future time. Conveniently, the flag portion also includes a hood, which may be detachable, so as to protect the target area from weather and debris such as dust and leaves. The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is an exploded front view of a first embodiment of combination

EDM target comprising a flag portion and base portion according to the invention, Figure 2 is an exploded side view relative to Figure 1 , Figure 3 is an exploded perspective view of the target of Figure 1 , Figure 4 is a perspective view of the combination flag portion and base portion in their assembled condition, Figure 5 is a part sectional exploded front view of a second embodiment of combination EDM target comprising a flag portion and base portion, Figure 6 is an exploded side view of the embodiment shown in Figure 5, Figure 7 is a perspective view of a third embodiment of combination EDM target, Figure 8 is a front view of the embodiment of Figure 7, Figure 9 is a side view of the embodiment of Figure 7, Figure 10 is a plan view of the base portion of the embodiment of Figure

7, Figure 11 is an underneath view of the flag portion of the embodiment of Figure 7, Figure 12 is an exploded part-sectional view of the base portion and flag portion of the embodiment of Figure 7, and Figure 13 is a sectional view of Figure 9. Referring firstly to Figures 1 and 2, an EDM target flag portion shown generally at 1 and base portion shown generally at 2 are made of a rigid, low hysterisis, fluorescent plastics material so as to provide high visibility in use even in poor ambient light conditions. The flag portion 1 comprises a central stem 3 on the upper end of which is a target area 4 having affixed thereto a square of reflective material 5 such as M3 LDP 7391 , onto which material are provided pre-printed cross hairs 6, 7 for facilitating accurate sighting by e.g. an EDM laser. Around the periphery of the target area 4 are compass points 8, 9 and 10 which facilitate alignment of the target area with e.g. a manual targeting laser level, although it will be appreciated that their use is optional, depending upon the sighting equipment being used. Below the target area 4 is disposed a marking area 11 which may, in use, be marked with information indicating e.g. the marking of TBM readings, although other information may be provided as desired. At the lower end of the stem portion 3 is a waisted region 12, shown more clearly with reference to Figure 2, permitting the upper portion of the stem 3 and hence the target 4 and marker area 11 to be tilted as required in the directions shown arrowed, the low hysterisis of the plastics material thereafter ensuring that such angular adjustment is retained. At the lower end of the stem portion 3 is a spigot 13 and associated flange 14, the spigot 13 being receivable in a correspondingly shaped slot 15

(shown in broken outline) in the base portion 2. As will be apparent, the spigot

13 can therefore be inserted within the slot 15 to the extent permitted by the flange 14. Turning now to Figure 3, it will be seen that the base portion 2 comprises a raised central region 16, which includes the slot 15, and is surrounded on either side by perforated foot portions 17, the perforations being used to key or anchor adhesive used to secure the base portion 2 to a fixed object such as part of the rail of a railway track. Turning now to Figure 4, it will be seen that the flag portion 1 has now been releasably mounted on the base portion 2 by virtue of the spigot 13 (not shown) being inserted into the slot at 15 (not shown) to the extent afforded by the presence of the flange 14, in which position the combination flag portion and base portion are ready for use. In use, the combination flag portion 1 and base portion 2 are assembled as shown in Figure 4, hereafter they are ready to be positioned as required on a fixed object, such as the foot or side web of a rail, although it will be appreciated that such may be on other fixed objects including e.g. over concrete or rock etc. However, a particular problem in the rail industry with the use of conventional targets is that if they are damaged for whatever reason they have to be replaced and reset, this being time consuming and also highly inconvenient given that the affected section of track has to be closed while this work is carried out. In contrast, however, it will be appreciated that when the combination flag portion 1 and base portion 2 have been initially positioned and the base portion 2 secured in place on the rail any accidental damage to the flag portion 1 , or even removal thereof by e.g. vandals, can be rectified by simply inserting the spigot end of a fresh flag portion 1 into the spigot 15 of the base portion 2 and even where angular adjustment thereafter has to be made by bending the stem 3 about the waisted region 12, it will nevertheless be apparent that this is still relatively easy as compared to removing, replacing and repositioning an entire target structure. Turning now to Figures 5 and 6, there is shown a second embodiment of combination EDM target to that shown with reference to Figures 1 to 4 where corresponding parts are numbered the same. In this embodiment the stem 3a is substantially circular in cross section and has at its lower end a waisted region

12a by which the entire assembly thereabove can be bent over as shown by the arrows adjacent the stem portion 3a. However, at the upper end of the stem portion 3a is another waisted region 18 allowing the target area 4 to be angularly moved relative to the stem 3a as shown by the arrows adjacent compass point 9 in Figure 6. This allows for greater adjustability of the target relative to e.g. an EDM laser device. This adjustability is enhanced by the presence of a (in this example) 12-sided polygonally shaped mounting spigot 19 integral with the side of a circular flange 14a below the waisted portion 12a, the mounting spigot 19 being slideably received within a correspondingly shaped polygonal socket 20 within the central region 16a of the base portion 17a. A snap fit locking spigot 21 extending from the centre of the mounting spigot 19 is adapted to be received within a correspondingly shaped bore 22 within the raised central region 16a of the base portion 2a, which bore is closed at one end to prevent ingress of e.g. adhesive applied to the lower surface of the foot portion 17a in order to secure it to e.g. the foot portion of a railway track. The flag portion 1a can thus be snap fitted into the base portion 2a, the polygonal mounting spigot 19 and corresponding polygonal socket 20 permitting the angular position of the target flag portion 1a to be adjusted about the major axis of the stem portion 3a. A further improvement is provided by the use of a hood or cowl 23 which surrounds the reflective material 5 and helps to shield it from the effects of weather and flying debris such as dust and leaves etc. This may be integral with the target area 4 but is preferably detachable so that replacements can be e.g. snap-fitted in place. A similar, preferred, embodiment is shown with reference to Figures 7 to 13 where like parts are numbered accordingly. In this embodiment the cowl 23a is much deeper to that shown in the second embodiment of the invention with reference to Figures 5 and 6 and is retained on the target area 4a by means of two pairs of oppositely disposed side clips 24 being received in correspondingly shaped recesses (not shown) on opposing sides of the target area 4a, thereby allowing the cowl 23a to be removed and replaced as necessary. The cowl also includes a lower floor portion 25 which therefore substantially encloses the periphery of the target area 4a and hence helps to protect it. In this embodiment, and as can be seen more clearly with reference to Figures 8 and 9, the waist region 12b is disposed at the lower end of the central stem 3b and is entirely circular but is not intended to bend in order to allow for tilting of the rest of the flag portion to permit alignment with an EDM beam. Instead, it simply provides a weakened portion of the stem 3b so that it can snap at that point to thereby reduce any tripping hazard the flag portion 1b may otherwise constitute. In this embodiment, tilting of the flag portion 1b relative to the base portion 2b is achieved by the use of wedge shaped shims (not shown), which can be inserted beneath base portion 2b when the target is first installed. The shims may find particular use with e.g. highly cambered rails requiring a more acute tilting of the target than normal and may also have projections or recesses co-operabie with projections or recesses in the foot portion 17b of the base portion 2b in order to aid assembly prior to fixing of the foot portion in its required position, such that the orientation of the target area 4a can be adjusted to face the direction required so as to align the target area 4a with an incoming laser beam. As can be seen with reference to Figures 10 to 13, the manner of assembly of the flag portion 1 b and the base portion 2b is the same as with the second embodiment shown in Figures 5 and 6 except that in this instance instead of the use of a 12-sided polygonally shaped mounting spigot 19 there is instead a hollow slightly tapered splined spigot 26 having 36 splines co-operable within correspondingly shaped splines 27 of a splined socket 28, thereby allowing radial adjustment by 10° increments. Conveniently, there may be markings around the periphery of the flag portion 1b and/or base portion 2b indicating a particular radial position of the flag portion 1b relative to the foot portion 2b such that after the perforated foot portion 17b and associated shim or shims have been permanently set and fixed in place, and thereafter when replacement of the flag portion 1 b is required, it can be easily returned to its correct radial orientation. As can be seen more clearly with reference to Figures 12 and 13, the foot portion 17b has a castellated locking spigot 29 disposed centrally within the splined socket 28 which has a flanged upper periphery 30 co-operable with a peripheral bead on the inside of the splined spigot 26 such that the latter can be releasably snap-fitted onto the castellated spigot 28 and hence the foot portion

17b. As will be apparent, the combination targets in accordance with the various embodiments of the invention described above provides significant advantages over the targets described in the preamble thereto in being easily adjustable and replaceable and although the invention has been described with reference to targets for use with EDM laser distance measuring devices it will be understood that such targets may find other uses without departing from the spirit or scope of the invention.

Claims

1. A combination target for distance measuring comprising a flag portion (1 , 1a, 1b) including a target area (4, 4a), the flag portion being adapted to be releasably secured to a base portion (2, 2a, 2b), the base portion being adapted to be secured to a fixed base structure, such as the rail of a railway track.

2. A target according to Claim 1 further characterised in that the flag portion (1 , 1a, 1b) is in the form of a stem (3, 3a, 3b), on the upper end of which is the target area (4, 4a) and on the lower end of which is a spigot (13, 26) adapted to be received within a correspondingly shaped slot or aperture (15, 27) within the base portion (2, 2a, 2b).

3. A target according to Claim 1 or Claim 2 further characterised in that the base portion (2, 2a, 2b) includes formations, such as holes or slots to provide a key or anchor for e.g. adhesive to be used to secure the base portion to a fixed structure such as the foot or side web of a rail.

4. A target according to any preceding Claim further characterised in that the flag portion (4, 4a) includes a marker area (11) below the target area to allow for reference information to be affixed thereto, such as an indication that a Temporary Bench Mark (TBM) reading is being or has been taken at the point where the target area is disposed above the base portion.

5. A target according to any preceding Claim further characterised in that the target area (4, 4a) comprises a reflective flag prism (5) such as M3 LDP 7391 providing high levels of reflectivity.

6. A target according to Claim 5 further characterised in that the flag prism (5) is provided with pre-printed cross hairs (6, 7) in order to facilitate accurate readings.

7. A target according to any preceding Claims further characterised in that compass points (8, 9, 10) are provided around the target area (4, 4a) to enable the use of manual targeting, such as through the use of laser levelling devices.

8. A target according to Claim 7 further characterised in that the compass points (8, 9, 10) project out of the target area (4, 4a) , each being at 90 degrees to other such compass points.

9. A target according to any preceding Claim further characterised in that the flag portion includes a stem portion (3, 3a) having one or more waisted regions permitting the flag to be bent and, through the use of a plastics material having low hysterisis, thereby permitting the angular orientation of the flag relative to the base portion to be adjusted relative to its original shape and, thereafter, to remain in such adjusted position.

10. A target according to Claim 9 further characterised in that the stem portion (3, 3a) is circular in cross section so as to offer little resistance to wind.

11. A target according to Claim 10 further characterised in that the stem portion (3, 3a, 3b) also includes an elbow or stepped portion where the base portion is intended to be affixed to an inclined or vertical surface, such as on one side of the central web of a portion of railway track to thereby permit the flag portion to be still orientated generally vertically prior to final adjustment.

12. A target according to any preceding claim further characterised in that the end of the stem portion (3a, 3b) remote from the target portion (4a) of the flag portion (1a, 1 b) is provided with formations and/or recesses (19, 26) engageable with corresponding formations and/or recesses (20, 27) in the base portion (2a, 2b) permitting the stem to be angularly adjustable about its major axis relative to the base portion.

13. A target according to Claim 12 further characterised in that the formations and/or recesses are polygonally shaped formations (19) and recesses (20) which inter-engage and which may be releasably secured in position by e.g. a spigot (21) extending from the stem portion (3a) into a correspondingly shaped aperture (22) within the base portion (17a) by means of e.g. a snap fit.

14. A target according to Claim 12 further characterised in that the formations and/or recesses are splines (26, 27) which are used to provide for greater adjustability, such as by the use of 36 splines on the spigot engagable with 36 grooves in the base portion, thereby allowing for radial adjustment at 10° increments.

15. A target according to any preceding Claim further characterised in that the flag portion (4, 4a) also includes a hood or cowl (23, 23a).

16. A target according to Claim 15 further characterised in that the hood or cowl (23, 23a) is detachable.

17. A combination target according to any preceding Claim further characterised in being adapted to be tilted by one or more wedge-shaped shims prior to the base portion being fixed in place.

18. A target according to any preceding claim in which the flag portion includes a stem having a waist region permitting the target area to snap off so as to avoid being a tripping hazard.

19. A combination distance measuring target substantially as hereinbefore described with reference to Figures 1 to 4.

20. A combination distance measuring target substantially as hereinbefore described with reference to Figures 5 and 6.

21. A combination distance measuring target substantially as hereinbefore described with reference to Figures 7 to 13.

22. Any individual component of the combination distance measuring targets substantially as hereinbefore described with reference to any one of Figures 1 to 13.