GB2117180A

GB2117180A - Magnetic supports

Info

Publication number: GB2117180A
Application number: GB08207971A
Authority: GB
Inventors: Reginald Flegg
Original assignee: BROWN ENGINEERS AND CONSTRUCTO; John Brown Engineers and Constructors Ltd
Current assignee: BROWN ENGINEERS AND CONSTRUCTO; Worley Field Services Ltd
Priority date: 1982-03-18
Filing date: 1982-03-18
Publication date: 1983-10-05
Also published as: GB2117180B

Abstract

A supporting device for a surveying instrument, e.g. an infrared reflecting beam tachometer 11, comprises a baseplate 2 and four pivotably mounted feet A, B, C, D each comprising a magnet 3 which may be switchable by means of a central section (3a, Fig. 3, not shown) reversible relative to the rest of the magnet 3. A magnet 3 may be pivotably mounted in its housing 4 thereby providing two orthogonal pivot axes. The device aids mounting on curved surfaces such as those of the steel spars of offshore oil rigs. <IMAGE>

Description

SPECIFICATION Magnetic supports The present invention relates in general to the use of a pivotally-mounted magnet as a support.

More particularly, the invention relates to supporting devices including such a magnet which can be used as a part of a mounting device for measuring instruments, for example, surveying instruments.

In surveying it is often necessary to measure distances between points that are not readily measurable by, say, tape measure, such as, for example, the distance between two points in a large steel structure e.g. an offshore oil rig. It is obviously essential that the measuring instrument is correctly and securely positioned. Thus, electronic distance measuring instruments are known, such as, for example, an infra-red reflecting beam tacheometer, e.g. the Wild Distomat D14, supplied by Wild Heerbrugg Ltd., of Heerbrugg, Switzerland, in conjunction with a mounting device comprising a baseplate supported by three legs, the three legs giving 3point contact with a host surface. Sometimes however, it is required to fix a measuring instrument to a surface which lies in a plane at an angle appreciably away from the horizontal and/or which is appreciably curved.In such circumstances the mounting must be capable of being firmly attached to the surface and/or of mounting the instrument at a stable and satisfactory orientation with respect to the surface. Such attachment mounting can be achieved by the use of, for example, bolts.

However, the use of the bolts requires careful alignment and securing. In addition fixed bolts inevitably damage the surface to which they are attached and hardly qualify as an easily reversible mounting. The present invention is concerned with a pivotally-mounted magnet which can provide a very versatile and easily removable support which does not damage the surface.

Accordingly, the invention provides the use of a pivotally-mounted magnet as a support.

The invention also provides a supporting device comprising a baseplate and a pivotallymounted magnet as a foot therefor.

The invention further provides a mounting device for a measuring instrument comprising a baseplate and at least two pivotally-mounted magnets serving as feet therefor, upon which baseplate is positioned a housing for the instrument.

The invention also includes a measuring assembly comprising a mounting device of the invention fitted with an infra red reflecting beam tacheometer, and an infra red beam prism reflector for use in conjunction with the tacheometer.

The invention further provides a method for attaching a measuring instrument to a magnetizable surface which comprises mounting the instrument on the baseplate of a supporting device of the invention and positioning the device on the surface using the magnetic attraction between the foot or feet and the surface to attach the device to the surface.

The present invention further includes a method for measuring distances comprising (a) positioning a measuring assembly of the present invention upon a magnetizable surface using the magnetic attraction between the foot or feet and the surface to attract the device to the surface and (b) employing the assembly in a conventional matter to measure distances.

In preferred embodiments the pivotallymounted magnet is provided with a gimbal mounting for greater versatility as a support.

It is highly preferred that the magnet be a reversed polarity magnet. Use of such a magnet ensures that a supporting device employing the same can be quickiy attached to or removed from a magnetizable surface. The reversed polarity magnet can comprise a central magnetic core rotatably positioned within an outer magnet and attached to a central spindle which enables the core to be rotated and hence, effectively, the overall reversed polarity magnet to be switched "on" or "off" at will.

The present invention will now be further described and illustrated by reference to the accompanying drawings, in which: Figure 1 is a perspective view of a pivotallymounted magnet of the present invention; Figure 2 is a cross-sectional view of the magnet of Figure 1 in the direction X--X'; Figure 3 is a cross-sectional view of the magnet of Figure 1 in the direction Y--Y'; Figure 4 is a perspective view of a supporting device of the present invention adapted as a mounting device to receive an infra red reflecting beam tacheometer; Figure 5 is a part of a cross-section of the device seen in Figure 4 along the line 5-5; Figure 6 is a part of a cross-section of the device seen in Figure 5 along the line 6-6;; and Figure 7 is a perspective view of a supporting device of the present invention upon which is mounted an infra red beam prism reflector for use in conjunction with the infra red reflecting beam tacheometer shown in Figure 4.

Identical reference numerals are used throughout the following description to indicate the same parts or components in the various drawings.

Referring first to Figure 1, reference numeral 1 indicates generally a pivotally-mounted magnet which is in use as a support. The overall structure illustrated in Figure 1 comprises a reversed polarity magnet 3 which is provided with a housing 4. The overall effect is of a gimbal mounted magnet since housing 4 is pivotally mounted to a plate 2 by means of projections 8 at opposite sides of housing 4 whilst magnet 3 is itself pivotally mounted to housing 4 by way of a spindle 6 passing through opposite sides of housing 4. The pivoting axis provided by projections 8 is substantially at right-angles to the pivoting axis provided by spindle 6. A switch 5 is provided at one end of spindle 6 exterior to housing 4. Rotation of switch 4 turns spindle 6 and rotates a plate 6a attached to spindle 6.

Referring now to Figure 2 of the drawings, plate 6a is connected by means of screws or other connecting means 7 to a central section of magnet 3 designated 3a. This central section is a rotatable magnetic core. Thus, turning of switch 5 turns spindle 6 and plate 6a and, in turn, rotates magnetic core 3a. The end of spindle 6 opposite to switch 5 is provided with a further plate 6b which is connected by further screws 7 to magnetic core 3a. The fit of spindle 6 through housing 4 and its rotation therein is facilitated by the provision of nylon washers 29 and 28 at opposite ends of spindle 6. The reversed polarity arrangement of magnet 3, with rotatable core 3a, enables, by operation of switch 5, the magnetic attraction between magnet 3 and the supporting surface (not shown) to be switched "on" and "off" at will.

In Figure 3 it can be seen that projections 8 sit in correspondingly shaped recesses 31 in plate 2.

Projections 8 are retained in recesses 31 by means of locating strips 9 (not shown in Figure 1).

As can be seen more clearly in Figure 4, locating strips 9 are fastened to plate 2 by bolts, screws or other connecting devices 32. In this way, projections 8 are held securely but rotatably in place. Nylon washers 30 are provided for each of projections 8.

For a combination of low weight and strength it is preferred that housing 4, spindle 6, plates 6a and 6b, and switch 5 all be made of aluminium.

Because projections 8 are relatively small, strength criteria dictate that they are preferably made of steel.

Figures 1 to 3 of the drawings illustrate, in general terms, the use of a pivotally-mounted magnet as a support. Thus, plate 2 can be the basis for equipment which is to be mounted on the supporting surface (not shown). Figures 4, 5, 6 and 7 when taken in conjunction, illustrate a specific application of the present invention. In particular, Figures 4, 5, 6 and 7 of the drawings illustrate the use of the invention to support an infra red reflecting beam tacheometer and its associated infra red beam prism reflector. Figures 4, 5 and 6 shows a unique mounting for the tacheometer and Figure 7 shows the mounting for the prism reflector.

In Figure 4, the mounting device is generally indicated by reference numerals 32. An infra red reflecting beam tacheometer is generally indicated by reference numeral 11. Mounting device 32 includes a supporting device consisting offourgimbal-mounted magnetic feet (a, b, c and d), each of which feet have the same structure as shown in Figures 1, 2 and 3 and describeed above, and a baseplate 2. Baseplate 2 is provided with elongated slots 27 (only one of which is shown in Figure 4) to permit hand-carrying of the device.

Mounting device 32 consists of the supporting device noted above together with an instrument housing generally designated 10. Housing 10 comprises an inner shell 12 and an outer shell 13.

Inner shell 1 2 is positioned within and suspended from outer shell 1 3. This latter suspension is achieved by means of fulcrum screw pins 14 connecting shells 12 and 13 (best seen in Figure 5). Shells 12 and 13 are both connected to a plate 33 which is secured to baseplate 2. An elongated slot 1 6 is provided through the floor 15 of outer shell 13 and a screw pin 17 is positioned within slot 16 connecting shell 13 to plate 33 and providing stability to this arrangement whilst restraining the possible lateral movement of shell 13 between pedestals 21 and 34.

Infra red reflecting beam tacheometer 11 (a suitable example of which is the Wild D14 Distomat-supplied by Wild Heerbrugg Ltd., of Heerbrugg, Switzerland) is mounted, when device 32 is in use, on a block 53 by means of spring clips 54 (Figures 5 and 6 in particular). Block 53 is positioned on the floor 1 8 of inner shell 12 and is a standard item manufactured and supplied by Wild Heerbrugg Ltd., of Heerbrugg, Switzerland.

The use of spring clips 54 is equivalent to a locking device ensuring that tacheometer 11 is permanently attached, for the duration of an operation, and can be used with the total assembly in any attitude. "Any attitude" meaning from being upright and horizontal through to being completely upside down.

Adjustment of the horizontal alignment of tacheometer 11 when in position in housing 10 is achieved by use of a screw arrangement generally designated 1 9. Arrangement 1 9 comprises a screw 20 mounted through a pedestal 21. One end of screw 20 abuts against the wall of outer shell 13. An opposite wall of outer shell 13 is positioned adjacent a resistance 22 which is mounted in a pedestal 34. As can be seen in Figures 5 and 6, outer shell 13 is able to pivot around screw pin 52 which fastens into plate 33.

Rotation of screw 20 pivots outer shell 13 around screw pin 52 within the limits dictated by the arrangement of screw 1 7 and slot 16.

Vertical alignment of tacheometer 11 when in position in housing 10, is effected by means of operation of a vertical motion screw 23. As can be seen best in Figure 6, inner shell 12 is maintained stable by pressure from a flat steel spring 50 fastened to the floor 1 5 of outer shell 13. The spring pressure acts upwards on the underside if shell 12 and at the opposite end thereof to screw 23. The operation of vertical motion screw 23 extends or retracts a pin 51 at its base and which bears down on the floor 1 5 of outer shell 1 3. A "rocking" movement may then be achieved through fulcrum screw pins 14.

The structure of instrument housing 10 described above (and the generality of concept which may be derived for such a structure and is expressed in the wording describing the particular features of claims 1 3 to 20 hereinafter regardless of the claim preambles is unique and is encompassed with the present invention concept.

However, the invention is not of course, limited to the use of aluminium. Any lightweight but tough material can be used and,in some applications heavier materials such as steel may be employed.

In some applications it is perfectly permissible to use plastics materials.

Turning now to Figure 7 of the drawings, a supporting device is shown which is generally designated by reference numeral 36. This comprises a plate 35 which is of similar structure to baseplate 2 shown in Figure 4 of the drawings.

Further description is, accordingly, superfluous. In addition, baseplate 35 is supported by four magnetic feet (designated e, f, g and h) which are identical in structure with the magnetic feet a, b, c and d shown in Figure 4 of the drawings. In the centre of baseplate 35 is mounted on infra red beam prism reflector 24 of conventional design. A suitable reflector is the Wild GHl prism reflector supplied by Wild Heerbrugg Ltd. of Heergrugg, Switzerland. The apparatus of Figure 7 in conjunction with the apparatus of Figures 4 to 6 constitutes a measuring assembly which permits the measurement of distances between points where the use of other measuring means such as, for example, a tape measure, is inappropriate or difficult.

As will be readily appreciated by the skilled man upon examining the structures of Figure 4 to 7, the use of gimbal-mounted magnets 3 as supports permits a supporting device to be provided, e.g. for a measuring instrument such as tachometer 11, which may be positioned upon a surface other than a flat surface and, in the case of a surface which is magnetizable, attached thereto by means of magnetic attraction. In particular, a problem frequently encountered in large scale engineering, such as the assembly of oil rigs for off-shore use, is the measurement of distances between relatively inaccessible parts. In the case of off-shore oil rigs, measurement between rig spars is rendered very easy by the use of a tacheometer as referred to above when employed in a manner using the principles of the present invention.It will be appreciated that in the case of a right cylinder, a single pivot axis for each magnet 3 would be sufficient for proper positioning of, say, device 32 on a steel or iron pipe or beam. However, any departure from a strict right cylindrical shape is, of course, provided for by the gimbal-mounting of magnets 3 in the preferred embodiments of the present invention.

The invention is, accordingly, not defeated by either high degrees of curvature or by departures from regularity of shape in terms of the underlying surface upon which the mounting or support device of the present invention is to be positioned or to which such device is to be attached.

In general terms, the use of a pivotallymounted magnet as a support provides many advantages in terms of supporting instruments or other items on magnetizable surfaces. The use of the devices of the present invention enables the provision of a method of attaching any measuring instrument to a magnetizable surface virtually independently of the precise shape of that surface.

It will be clearly appreciated that although in the preferred embodiments described above the two pivot axes for magnet 3 are substantially at right-angles this is not essential. As already indicated, in some applications a single pivot axis may be sufficient whilst in others it may be desirable or possible to use two pivot axes which are aligned with respect to each other at an angle less than a right-angle. The principle of the present invention is extremely flexible in terms of its application.

Claims

1. The use of a pivotally mounted magnet as a support.

2. A supporting device comprising a baseplate and a pivotally mounted magnet as a foot therefor, preferably a reversed polarity magnet.

3. A device as claimed in claim 2, wherein the foot is mounted to the plate by a gimbal arrangement.

4. A device as claimed in claim 3, wherein the foot is provided with a housing, the gimbal arrangement comprising a first pivot for the foot in the form of a spindle passing through the magnet and each end thereof also passing through the housing, and a second pivot for the foot in the form of a projection on each of opposite sides of the outside of the housing and rotatably mounted to the baseplate, there being no other connection between the housing and the baseplate.

5. A device as claimed in claim 4, wherein the projections are mounted in correspondinglyshaped recesses in the baseplate and are each held therein by a respective locating strip fastened across the recess.

6. A device as claimed in claim 4 or claim 5, wherein the projections are short spindles extending from the housing.

7. A device as claimed in any one of claims 4 to 6, wherein the pivot axis provided by the spindle passing through the foot is substantially perpendicular to the pivot axis between the housing projections.

8. A device as claimed in any one of claims 4 to 7, wherein the baseplate and housing are made of aluminium.

9. A device as claimed in any one of claims 2 to 8 including at least two, preferably four, of said pivotally-mounted magnets as feet.

10. A device as claimed in claim 2 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

11. A mounting device for a measuring instrument comprising a housing for the instrument positioned upon the baseplate of a device as claimed in any one of claims 2 to 8, there being at least two of said pivotally-mounted magnets serving as feet.

12. A device as claimed in claim 11, wherein the instrument housing is adapted to receive an infra red reflecting beam tacheometer.

13. A device as claimed in claim 12, wherein the instrument housing comprises an outer shell and an inner shell pivotally supported in the outer shell for holding the tachometer.

14. A device as claimed in claim 13, wherein the inner shell is supported within the outer shell by means of two oppositely positioned screw pins, each screw pin passing through one wall of the outer shell and one wall of the inner shell.

1 5. A device as claimed in any one of claims 12 to 14, wherein the instrument housing is horizontally moveable and provided with an adjustable screw arrangement for altering the horizontal alignment of the housing.

16. A device as claimed in claim 15, wherein the adjustable screw arrangement comprises a pedestal located adjacent to one end of one wall of the outer shell with an adjustable screw mounted through the pedestal and having one end thereof abutting said one wall, and means located adjacent an opposite wall of the outer shell for providing resistance of the outer shell against said one end of the screw the outer shell floor being connected when the screw is adjusted, to the baseplate by means including a screw pin so as the enable the floor to pivot around the pin and relative to the baseplate.

17. A device as claimed in any one of claims 1 3 to 16, wherein means is provided for adjusting the vertical alignment of the tachometer comprising an arrangement for altering the alignment of the inner shell relative to the outer shell.

18. A device as claimed in claim 17, wherein the vertical alignment adjusting means comprises a spring providing resistance between outer and inner shells on one side of the pivotal connection between the shells and screw adjusted means on the opposite side of the pivotal connection between the shells for opposing the action of the spring so as to enable the inner shell to be "rocked" around the pivotal connection.

19. A device as claimed in any one of claims 13 to 18, wherein the instrument housing is attached to the supporting device by means of a screw the head of which is positioned in an elongated slot in the floor of the outer shell.

20. A device as claimed in any one of claims 12 to 19, wherein the instrument housing is made of aluminium.

21. A device as claimed in any one of claims 12 to 20, wherein the baseplate is provided with an elongated slot adapted to permit hand holding of the device.

22. A device as claimed in claim 12 and substantially as hereinbefore described with reference to and as illustrated in Figures 4 to 6 of the accompanying drawings.

23. A measuring assembly comprising: (a) a device as claimed in any one of claims 12 to 22 fitted with an infra red reflecting beam tacheometer; and (b) an infra red beam prism reflector for use in conjunction with the tacheometer.

24. A measuring assembly as claimed in claim 23, wherin the prism is mounted upon a supporting device as claimed in any one of claims 2to 10.

25. An assembly as claimed in claim 23 and substantially as hereinbefore described with reference to and as illustrated by Figures 4 to 6 and 7 of the accompanying drawings considered in combination.

26. A method for attaching a measuring instrument to a magnetizable surface which comprises mounting the instrument on the baseplate of a supporting device as claimed in any one of claims 2 to 10 and positioning the device on the surface using the magnetic attraction between the foot or feet and the surface to attach the device to the surface.

27. A method as claimed in claim 26, wherein the magnet is a reverse polarity magnet.

28. A method as claimed in claim 26 and substantially as hereinbefore described.

29. A method for measuring distances comprising (a) positioning an assembly as claimed in any one of claims 23 to 25 upon a magnetizable surface using the magnetic attraction between the foot or feet and the surface to attract the device te the surface and (b) employing the assembly in a conventional manner to measure distances.

30. A method as claimed in claim 29 and substantially as hereinbefore described.