US3044740A

US3044740A - Supports for high sensitivity devices

Info

Publication number: US3044740A
Application number: US42922A
Authority: US
Inventors: Pearce Derek Charle Kilminster; Tolmon Francis Richard
Original assignee: National Research Development Corp UK
Current assignee: National Research Development Corp UK
Priority date: 1959-10-20
Filing date: 1960-07-14
Publication date: 1962-07-17
Anticipated expiration: 1979-07-17

Description

July 17, 1962 D. c. K. PEARCE ETAL 3,

SUPPORTS FOR HIGH SENSITIVITY DEVICES Filed July 14, 1960 2 Sheets-Sheet 1 July 17, 1962 D. c. K. PEARCE ETAL 3,044,740

SUPPORTS FOR HIGH SENSITIVITY DEVICES Filed July 14, 1960 2 Sheets-Sheet 2 HIIIIIIIIIIIIIIIIW fig. 2.

48 g 4 Q9 6/ g i i J I 5 F-+-- 3,044,740 SUPPORTS FOR HIGH SENSITIVITY DEVICES Derek Charles Kilminster Pearce, Shepperton, and Francis Richard Tolmon, Ellingham, England, assignors to National Research Development Corporation, London, England, a corporation of Great Britain Filed July 14, 1960, Ser. No. 42,922 Claims priority, application Great Britain Oct. 20, 1959 13 Claims. (Cl. 248-124) The present invention relates to supports for high sensitivity devices such as high sensitivity indicators or dial gauges and its object is to provide a support which while being robust enables the position of the supported device to be adjusted with a very great degree of fineness without backlash. I

According to the invention the support comprises a heavy base to stand on a surface table or the like, a vertical metal column firmly anchored to the base to which the supported device can be directly or indirectly secured, and means for applying an adjustable bending moment to the metal column. The elastic deflection so caused moves the supported device bodily and thus adjusts its position. 7

Care must be taken to limit the bending moment applied to a value which keeps the stresses below the elastic limit in the column. A convenient arrangement is to make the column hollow and to anchor in its outer end a plug carrying a cantilever which extends inwardly along the axis of the column towards the base. The bending stress is then applied by imposing a load transversely to the axis at the lower end of the cantilever. The dimensions may be designed so that the end of the cantilever touches the wall of the column before the elastic limit is reached oran adjustable stop may be provided.

A convenient way of applying the necessary forces to the cantilever is a fine pitched screwarranged horizontally and screwing through the base and lower end of the column.

An alternative to a screw adjustment would be a cam but usually a screw adjustment is simpler to provide.

By making the column of constant cross-section and providing it with clamping means for a direct or indirect attachment of the supported device, the latter can be adjusted in the longitudinal direction of the column, while if the column is of circular external cross-section, the supported device can be adjusted around the axis of the column. Desirably the support is equipped with an arm held by the clamping means, the device being attached to the arm, thus enabling the distance of thedevice from the column to be adjusted, and if the arm is of circular cross-section enabling the device to be rotated about the axis of the arm. The clamping means may then also be arranged so that when loosened it permits the arm to be swung about an axis perpendicular to the column.

Since when it is bent the column will take a curved form in the vertical i.e. axial plane in which the bending forces are applied, the actual amount of movement of the supported device can be varied by clamping the arm supporting it to different points along the length of the column, or by swinging the arm around the column, or by a combination of both.

If the supported device is an indicator it may be arranged with its axis horizontal or vertical or in any other desired direction. Any component of the movement imparted to the indicator by its support in the direction of the indicator axis may be used as a zeroing adjustment, the magnitude of this adjustment depending upon the attitude of the indicator in relation to the base and column.

The invention will be further described with reference Patet I enables the arm 41 to be moved along and swung round to the accompanying drawings which illustrates an example embodying it. 5

FIGURE 1 is an-elevation partly in axial section, of

the complete support,

the cantilever reaching almostto the lower end of the column 12. I

To apply a bending force to the tube 12 afine-pitched spherical-ended screw 1S with a thumb piece 16 is set in the base at right angles to the cantilever Hand to provide a suitable surface against which the spherical end of the screw can abut, a flat 17 is machined in the canti- 1 lever. The thread in which the screw 15 turns is desirably provided in a Phosphor-bronze nut 18 held in the base 11 by'screws 19. -A screw 21, locked by a screw 22 acting through a soft (lead) plug 23, serves to provide an adjustable stop limiting the deflection which can be applied to the cantilever 14. Another screw 24, locked by a screw 25 acting through a soft (lead) plug 26, serves to impart an initial deflection to the cantilever 14, and in conjunction with the screw 21 to limit the range of deflection which can be imparted by the screw .15.

The base 11 is preferably provided with three support pads, two of which marked 27 are visible in FIGURE 1, to avoid any risk of rock. The rest of the base may be coated with a relatively thick layer of plastic such as polyvinyl chloride.

A bracket 28 has a groove 29 to. engage the column 12 and is drawn against and clamped to the column by a flexible metal band 31 which encompasses the column and is drawn into a recess in the bracket by a screw. A convenient screw arrangement comprises a threaded shank 32 having a part-spherical head 33 engaging a wedge shaped block 34 to whichv the ends of the band 31 are attached as by hard soldering, the shank 32 being drawn into the bracket 28 by the aid of a knurled hand nut 35. A compression spring fidensures release when the nut 35.is loosened. I t

A pad member 37 having a truncated conical portion 38 seats in a corresponding conical bore in'the bracket 28 with its axis perpendicular to .(but not intersecting) the axis of the column 12. The pad member 37 has a grooved seating 39 perpendicular to its axis, for a cylindrical arm 41, the arm being drawn and clamped against the seating 39 by a metal band 42 encompassing the arm and drawn into the pad member by a screwpwhich again conveniently comprises a threaded shank43 and knurled hand nut 44, while a compression spring 45 again ensures release when the nut 44 is loosened.

This construction of the bracket and clamping means the axis of the column 12 and also enables the arm 41 to be moved longitudinally and rotated on its own axis in relation to the bracket 28 and to be swung about the axis of the cone 38.

If the arm 41 is to support an indicator, the indicator stem may similarly be clamped by a metal band 46 encompassing it, which draws it into a grooved seating in a head 47 at one end of the arm, the arm being tubular and the screw shank extending axially along it so that the knurled hand nut 48 is located at the other end of the arm. I

Conveniently the arm 41 may be of the same diameter as the stem of the indicator in which caseby removing 3 the arm 41 the indicator can be clamped in its place directly to the bracket 28 i.e. to the column 12.

The above described construction of clamping means has the advantage that along with low weight a high degree of rigidity can be obtained without the need for precision of manufacture of the bracket, column or arm. Though the clamps are intended for use with one nominal size only they will readily accommodate and work satisfactorily on parts, the diameter of which has variations of several thousandths of an inch. Thus the column and arm may be made of centreless ground tubing. A further advantage is that the clamping means has high mechanical advantage and is easily operated.

For a column 12 of say one inch diameter and an arm 41 and indicator shank of three quarter inch diameter the metal band may be of 0.020 thick spring steel strip 9 inch wide and A inch wide respectively and the screwed shank may have a A inch B.S.F. thread. In the case of the clamp holding the arm 41 to the bracket 28 through the tapering seating 38, a fairly large diameter of nut 44 is desirable, say one and a half inch, to ensure adequate clamping force to lock the tapers together. Smaller diameters are suitable for the

other nuts

35 and 48 say one inch. The bracket 28 may be of cast iron with the groove 29 taking the form of two substantially semi-circular seatings for the column 12 spaced apart to avoid the possibility of rock. Similarly the pad member 37 and head 47 may have the groove taking the form of two spaced substantially semi-circular seatings for the arm 41 and indicator stem respectively.

We claim:

1. A support for a high sensitivity device comprising a base, a hollow vertical column firmly anchored to the base, a cantilever having an axis and having one end fixed to the upper end of the column, said cantilever extending substantially within the column and clear of the inner wall of said column, and means for applying a load to the cantilever transverse to said axis, thereby imposing a bending moment on the column.

2. A support according to claim 1 and further comprising an adjustable stop to limit the maximum deflection of the cantilever.

3. A support according to claim 1 and further comprising an adjustable stop to impart an initial deflection to the cantilever.

4. A support according to claim 1, in which the means for applying a load to the cantilever comprises a screw screwing through the base and lower end of the column.

5. A support according to claim 1 in which the column is of constant external cross section and further comprises clamping means for attachment of the supported device.

6. A support according to claim 1 in which the column is of circular external cross-section.

'7. A support according to claim and further comprising an arm held by the clamping means.

8. A support according to claim 7 in which the arm is of circular cross-section.

9. A support according to claim 7 in which the clamping means comprises a pivot perpendicular to the arm and to the column, about which the arm can be swung when the clamp is loosened.

10. A support according to claim 5 in which the clamping means comprise a bracket having a groove to engage the column, a flexible band which encompases the column and a screw which when tightened draws the band into a recess in the bracket thereby drawing the bracket against and clamping it to the column.

11. A support according to claim 5 in which the clamping means includes a bracket having a conical bore with its axis perpendicular to but not intersecting the axis of the column, a pad member having a truncated conical portion seating in the bore, the pad member having a grooved seating perpendicular to its axis, a metal band adapted to encompass a member to be secured, and a screw which when tightened draws the band into a recess in the pad member, and the pad member into its seating in the bore.

12. A support according to claim 10 and further comprising an arm, a head on the end of said arm having a grooved seating to receive the supported device, a band adapted to encompass the supported device, and a screw actuatable at the other end or" the arm to draw the band into a recess in the head.

13. A support for a high sensitivity device comprising a base, a hollow vertical column of circular cross-section firmly anchored to the base, a cantilever within the column anchored to the outer end thereof and extending inwardly towards the base, an adjusting screw screwing through the base transversely to the column and abutting said cantilever, a bracket having a first grooved seating for the column and a conical bore to one side of the seating with its axis perpendicular to but not intersecting the axis of the column, a first band encompassing the column in the region of the grooved seating, a first clamping screw to draw the ends of said first band into a recess in the bracket thereby to clamp the bracket to the column, a pad member having a truncated conical portion seating in said conical bore, said pad member also having a second grooved seating perpendicular to its axis, a hollow circular section arm, a second hand encompassing the arm in the region of the second grooved seating, a second clamping screw to draw the ends of said second band into a recess in the pad member and at the same time draw the pad member against said conical bore, a head member on one end of the arm having a transverse third grooved seating in its outer face to receive the supported device, a third band adapted to encompass the supported device, and screw means actuatable from its other end of the arm for drawing the ends of the third band into a recess in the head.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Aug. 1, 1956 ha e