US2512304A

US2512304A - Vibrating table

Info

Publication number: US2512304A
Application number: US654288A
Authority: US
Inventors: Calver Cyril Maurice Grahame
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-03-15
Filing date: 1946-03-14
Publication date: 1950-06-20
Anticipated expiration: 1967-06-20

Description

June 20, 1950 c. M. G. CALVER 2,512,304

VIBRATING TABLE Filed March 14, 1946 H 5 Sheets-Sheet 1 K M29? 5/ wlggw/ffi June 20, 1950 c; M. e. CALVER 2,512,304

VIBRATING TABLE Filed March 14, 1946 5 Sheets-Sheet 2 Wwawvz 6/6/4 W6 54.11456 SEARCH H t M. G. CALVER VIBRATING TABLE June 20, 1950 5 Sheets-Sheet 4 Filed March 14, 1946 Jame 20, E950 c, M. G. CAM/ER sfi y VIBRATING TABLE Filed March 14, 1946 5 sneew-smm 5 Patented June 20, 1950 VIBRATING TABLE Cyril Maurice Grahame Calver, Bushey, England Application March 14, 1946, Serial No. 654,288 In Great Britain March 15, 1945 11 Claims.

This invention consists in improvements in or relating to vibrating tables which have been particularly designed for testing aircraft instruments under conditions which can be adjusted to simulate very closely the vibration conditions to which those instruments would be subjected when the aircraft carrying them is in flight. Although the invention is primarily designed for this purpose it is to be understood that it is not limited to this use and may be employed for any purpose in which a vibrating table is required to be vibrated in two planes disposed at an angle to one another, e. g. at a right-angle and in which the phase relationship of vibrations can be readily adjusted.

The present invention comprises broadly in combination a vibratory table, a carriage for the table permitting movement of the latter in two planes angularly displaced, at least two rotary shafts having an eccentric coupling to the table with the two shafts disposed with their axes angularly displaced with respect to one another at the required angle and means to adjust the eccentricity of the coupling between each shaft and the table.

One preferred example of the invention will now be described with the aid of the accompanying drawings in which:

Figure 1 is a side elevation showing the vibration table together with the main driving motor, Figure 2 is a section on the 22 of Figure 1,

Figure 3 is a section in a plane at right-angles to that of Figure 2 and containing the axis of the main driving shaft.

Figure 4 is a section of a detail taken on the line 4-4 of Figure 3, and

Figure 5 is a diagrammatic illustration of a portion of the vibratory shaft shown in Figure 2 to i1- lustrate more clearly the eccentricity of the shaft and the several parts associated with it.

Figure 6 is an exploded view of the main parts making up the vibratory table and sub-frame and Figure 7 is an enlarged sectional detail of the coupling to one of the main vibration shafts and the means for angularly adjusting it.

Like reference numerals indicate like parts in the several figures of the drawings.

The main base I0 upon which the table is supported may be of any preferred form and is conveniently a metal casting in which are provided bearings II and I2 for main driving shaft I3.

, Driving through a coupling 85 this shaft rotates driving shaft I I3 to which is splined a bevel gear I4 with which are engaged two other bevel gears I 5 and I6 mounted respectively on two vibration shafts I1 and I8. One of these vibration shafts, namely the shaft I1, is arranged with its axis at right-angles to and in a plane containing the axis of the main driving shaft H3. This shaft as shown in Figure 5, has ground ends I I! which rotate in the shaft bearings, the centre portion I9 is eccentrically ground to ends I IT. This centre portion I9 carries a tightly fitting sleeve 20, the outside of which is also ground eccentric with its own bore and the centre portion I9. The axes for the respective parts I1, I!) and 20 are indicated at

2I

22 and 23 respectively. It is to be understood, however, that eccentricity of the various parts is grossly exaggerated in the illustration in order to show the relationship of these eccentrically designed parts, and in practice, as only comparatively small vibrations are required the degree of eccentricity in all cases will be comparatively slight.

Sleeve 20 is in actual construction, as shown in Figure 2, composed of three portions, 24, 25 and 26 of which the

outer portions

24 and 26 are carried in bearings indicated as a whole by

reference numerals

21 and 28. These bearings are carried in housings 29 and 30 provided in the bottom of a sub-frame 3| to which vertical vibrations will be imparted when shaft I1 is rotated.

As shown more clearly in Figures 3 and 6, the vibratory table 32 is supported on sub-frame 3| through the medium of a spaced series of balls 33 which are housed in a ring 34 so that vertical motion is transmitted from the sub-frame to the table through balls 33. At the same time these balls provide an anti-friction support for table 32 when it is to partake of vibrations, say in the horizontal plane or in any plane in which a second series of vibrations is intended.

In the example shown, the two sets of vibrations are intended to take place in two planes at right angles to one another, and in consequence the vibration shafts I1 and I8 are disposed with their axes at right angles to one another.

Sub-frame 3|, which is mounted by the bearings described on shaft I1, is guided for its vertical movements by means of a plate I3I. This plate has tenons I32 arranged vertically one above the other to engage in corresponding grooves in an end bearing standard I00, and on the opposite face has other tenons I33 in line at right angles to tenons I32, and these tenons I33 slide in grooves formed to correspond with them in the wall of sub-frame 3|.

A similar plate I34 is interposed between subframe 3| and table 32, the latter having grooved uides I35 to engage tenons I36 on plate I34. The latter also has other tenons I31 which enage in grooved guides I38 in sub-frame 3 I. Thus, it will be clearly seen that the vibratory table can move independently of the sub-frame in its guides in one direction, and is bodily moved by the subframe in a direction at right angles, this latter movement of the sub-frame being permitted and guided by reason of the provision of plate I3 I.

The three

portions

24, 25 and 26 of the sleeve are interengaged by dogs as shown at 35 and are held thus in engagement with one another after assembly by means of thrust bearing 36. The outer end of sleeve portion 24 where it projects from hearing housing 29, is formed as one element of a comparatively finely toothed clutch 31 and this oo-operates with a second companion clutch element 38, splined on the left hand end of shaft I1. Thus the clutch element 38 may be moved into and out from engagement with the clutch element 31 in order to lock or free the

sleeve

24, 25 and 26 to and from shaft I1 respectively.

When adjusting the amplitude of vibration imparted from shaft I1 relative rotation between the shaft and its sleeve will have to be made and for this adjustment the

clutch

31, 38 is actuated by the following means.

Shaft I1 is formed with a screw threaded enlargement 61 and this is engaged by nut 68. In the nut 68 is formed a groove accommodating a split ring 18 which is housed in a recess formed in gear ring 13. The split ring and gear ring 13 are secured to clutch member 38 by means of screws and dowels, holes 12 are drilled in the nut to give access to these screws and dowels. The gear teeth on gear ring 13 are engageable when

clutch

31, 38 is disengaged by pinion 14 secured to and rotatable with shaft 15. The shaft 15 is slidable in bearing 16 and is normally spring urged outwardly by means of spring 11 compressed between the end of bearing 16 and the interior face of a cap 18 which is screw-threaded on to shaft 15 and is secured thereon by means of a lock nut 19.

A sleeve 84 with clutch teeth machined on one end is secured to shaft 15 by means of a pin 89 and is engageable by a similar sleeve 8| with clutch teeth formed thereon. The sleeve 8| is secured to crank handle 82.

Thus when the

clutch

31, 38 has been disengaged as shown in Figure 2, crank handle 82 can be applied to shaft 15 and the whole moved inwardly against spring 19 until pinion 14 meshes with gear ring 13. Rotation of crank handle 12 will then rotate shaft I1 because clutch member 38 is splined as at 83 to shaft I1.

After the shaft has been adjusted to its required angular position crank handle 82 is removed, spring 11 moves shaft 15 to withdraw pinion 14 from engagement with gear ring 13 and thereafter by turning nut 68 the clutch part 38 will be moved back into engagement with clutch part 31. As nut 68 can rotate freely with respect to ring 10, the clutch part 38 will not be rotated when nut 68 is rotated, and rotational movement of the latter, by engagement with thread 61 will, according to direction of rotation, move the clutch member in one direction or the other. The outer surface of nut 68 is formed to be readily engageable by a tool by which it can be rotated when desired.

One of the

clutch elements

31, 38 is marked on the outside with a scale to which a setting mark on the companion element can be adjusted in order to regulate and ascertain the angular movement of the sleeve relatively to the shaft for the purpose of adjusting the throw which will be imparted vertically to the sub-frame 3| as shaft I1 is rotated. Thus adjustment is, of course, obtained by altering the angular relationship of the eccentric portions of the shaft and sleeve.

A second and similar vibratory shaft I8 (Figure 3) and similar adjusting devices therefor are provided. As in the main, the shaft I8 and its sleeve 44 will be similar to the shaft I1 and its sleeve, no detailed description of this second vibratory shaft construction is thought to be necessary but it should be stated that in this case the two clutch elements corresponding to 31, and 38 are indicated at 48 and 4|. Lock nuts 42 and 43 are provided to hold the clutch parts 46 and 4| in engagement after they have been sent relatively to one another to produce the relative angular adjustment required between the eccentric portions of shaft I8 and its surrounding eccentric sleeve 44.

After clutch parts 48 and 4| have been separated a tool I40 can be applied to clutch part 4| in order to turn shaft I8 within its sleeve in a similar manner to and for the same purpose as that for which shaft I1 is angularly adjustable relatively to its sleeve after

clutch

31, 38 has been disconnected.

Sleeve 44 is received in anti-friction bearing 45 carried by table 32 so that horizontal vibrations are imparted directly to the table. Thus the latter can be subjected to vertical vibrations from shaft I1 and horizontal vibrations fromshaft I8 and the amplitude of the vibrations derived from the rotation of both these shafts is capable of adjustment in very fine degrees from zero to whatever maximum is imposed by the degree of an eccentricity of the shafts and sleeves.

When it is necessary to adjust the phase angle of the vibrations imparted to table 32 from vibratory shafts I1 and I8, it is necessary to rotate one or the other or both of these shafts in company with its sleeve without disturbing the angular adjustment between that shaft and its sleeve. For this purpose it is necessary first to free the main driving bevel gear I4 from driving engagement with bevel gears I5 and I6.

In order to enable this disconnection to be effected the driving shaft is in two parts I3 and H3. One part I3 is mounted in bearings II and I2 and the other, H3 is mounted in bearings 41 carried in housing 48 which is itself carried in a bracket 49 at the base of sub-frame 3|, so as to be movable axially.

The driving power is transmitted from the driving shaft I3 to the other 3 by means of a universal coupling 85, one half of which is secured by splines to I 3. The other half I I3 is splined to the coupling but not secured, allowing driving shaft 3 to be axially movable therein when moving the housing 48 which carries the shaft H3 and the bevel gear I4 which is splined to it, into the disengaged position.

The main bevel gear I4 is disengaged by means of a hand wheel 55 secured by a pin to a screw 53. The screw is mounted in a bearing 54 secured to the side of sub-frame 3|, any unintentional axial movement of screw 53 being eliminated by adjusting two locknuts 58. As the handwheel 55 and screw 53 rotate in one direction, the screw operates the rack 52 which is carried in a guide 5| formed in the top of the bracket 49. The rack meshes with the teeth 56 formed onv the housing 48 and rotates the housing. This SEARCH rotational movement is converted into an axial movement by co-operation of the helical slot 56, formed in housing 48, and an actuating pin 51. This actuating pin is secured by means of a thread and pin 81 to the base of bracket 49. Thus shaft H3 is moved endwise so as to carry the main bevel gear l4 out of engagement with pinions I5 and I6 when it is desired to adjust the phase angle.

The main bevel gear [4 is engaged by rotating the handwheel 55 in the opposite direction to that described for disengagement so operating the screw 53 and rack 52 and rotating the housing 48 which moves axially, owing to the helical slot 56 and the actuating pin, back to engaged position. When engaged position is reached the housing is held by the rack, which stops rotary movement and is locked between the actuating pin and the locking plate 86; this stops axial movement. The locking plate 86 is secured to the back of the housing 48 by means of screws. Thus shaft H3, is moved back to engaged position carrying main bevel gear M to its original position meshing with pinions l5 and Hi.

The main drive can be obtained by any preferred prime mover, such as an electric motor 60, as shown in Figure 1. As it is difiicult commercially to obtain a motor which can be run at any speed from zero to the high speeds required, it is preferable to employ a motor having a slower maximum speed than that requisite for the maximum vibration speed and to gear this motor by a 2:1 step-up gear or a step-up gear of any other preferred ratio as may be found necessary. The motor shaft 6|, as will be seen in Figure 3, is thus geared by step-up gearing 62 to shaft l3.

In the case of certain aircraft instruments it is sometimes necessary that the internal mechanism thereof should be rotated during the vibration test. For this purpose a flexible drive is provided, indicated in Figure 1 at 63 and this flexible shaft is driven by a comparatively small motor (not shown) housed within the base portion of the apparatus. For the sake of illustration, flexible shaft 63 is shown as connected to the driving spindle to one or more of the instruments in an instrument panel 64 shown in the position in which it will be carried between brackets 65 supported on the main table 32. Flexible shaft 63 will preferably be provided at 66 with a nipple or other connector by which it can be readily attached to and detached from the instrument spindle.

It will be understood from the foregoing description that the vibratory table can be subjected simultaneously to vibrations in two different planes and that the eccentric portions of the vibratory shafts in relation to the eccentric sleeves surrounding them can be adjusted to produce vibrations ranging from zero to the desired maximum. Hence vibrations of any magnitude from zero to this maximum can be applied to table 32 in either plane singly or in both planes simultaneously and moreover the phase angle of the two sets of vibrations can be readily and rapidly changed as and when desired in addition to changing the amplitude thereof.

I claim:

1. A vibration test machine comprising in combination a vibratory table, a carriage for the table permitting movement of the latter in two planes angularly displaced, at least two rotary shafts, each having an eccentric coupling to the table, with the two shafts disposed with their axes angularly displaced with respect to one another at the required angle, and means to adjust the eccentricity of the coupling between each shaft and the table.

2. A vibration test machine according to claim 1 in which the operative portion of each vibration shaft is formed, as to its outer surface, eccentrically with respect to the axis of rotation of the shaft.

3. A vibration test machine according to claim 1 in which part of the eccgM En g Q Q N-..

each vibration shaft and the table comprises a sleeve which surrounds the shaft and which has its operative surface formed eccentrically with respect to its through-way axis.

4. A vibration test machine according to claim 1 in which part of the qssn isicsgslinebsinge each vibration shaft and the table comprises a sleeve which surrounds the shaft and which has its operative surface formed eccentrically with respect to its through-way axis, and in which each vibration shaft is coupled to its associated sleeve by means of adisconnectable coupling.

5. A vibration test machine according to claim 1 comprising a main driving shaft, a main driving gear rotated thereby, other gears which mesh with the main driving gear and are coupled respectively to the vibration shafts, and means to connect and disconnect at will the main driving gear from the two driven gears.

6. A vibration test machine according to claim 1 comprising a main driving shaft, a main driving gear rotated thereby, other gears which mesh with the main driving gear and are coupled respectively to the vibration shafts and means to connect and disconnect at will the main driving gear from the two driven gears, said means comprising a bearing carrying the main driving gear, means for rotatably mounting the bearing in a support, means to rotate the bearing, and a cam device operable on the bearing as it is rotated for moving it axially.

7. A vibration test machine according to claim 1 comprising a main driving shaft, a main driving gear rotated thereby, other gears which mesh with the main driving gear and are coupled respectively to the vibration shafts, means to connect and disconnect at Will the main driving gear from the two driven gears, said means comprising a bearing carrying the main driving gear, means for rotatably mounting the bearing in a support, means to rotate the bearing, and a cam device operable on the bearing as it is rotated for moving it axially, the said means for rotating the bearing comprising a tangentially disposed rack meshing with gear teeth formed on the outer surface of the bearing, and operating means to move the rack endwise to rotate the sleeve.

8. A vibration test machine according to claim 1 comprising a main driving shaft, a main driving gear rotated thereby, other gears which mesh with the main driving gear and are coupled respectively to the vibration shafts, means to connect and disconnect at will the main driving gear from the two driven gears, said means comprising a bearing carrying the main driving gear, means for rotatably mounting the bearing in a support, means to rotate the bearing, and a cam device operable on the bearing as it is rotated for moving it axially, the said means for rotating the bearing comprising a tangentially disposed rack meshing with gear teeth formed on the outer surface of the bearing, and operating means which serves to move the rack endwise and comprises a lead screw engaging the rack and rotatable in fixed hearings in the machine.

9. A vibration test machine according to claim 1 comprising a main driving shaft, a main driving gear rotated thereby, other gears which mesh with the maindriving gear and are coupled respectively to the vibration shafts and means to connect and disconnect at will the main driving gear from the two driven gears, said means comprising a bearing carrying the main driving gear, means for rotatably mounting the bearing in a support, means to rotate the bearing, and a cam device operable on the bearing as it is rotated for moving it axially, the said cam means comprising a slot and a pin working therein whereof the slot and pin are provided one on the bearing and one on a fixed guide in which the bearing is axially movable.

10. A vibration test machine according to claim 1 in which the operative, portion of the sleeve 20 surrounding one of the vibration shafts is received within a bearing in the table itself, and the latter is mounted on a sub-frame over which itcan move under vibrations imparted by the shaftjust referred to, and the operative portion of the sleeve of the other vibration shaft is received in a bearing carried by the sub-frame.

11. A vibration test machine according to claim 1 in which an auxiliary motor is housed within the .machine and a flexible driving shaft connected with the motor is provided for attachment to a rotating part of an instrument to be tested for vibration by the machine.

CYRIL' MAURICE GRAHAME CALVER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,774,769 Spear July 19, 1927 1,901,122 Robins Mar. 14, 1932 2,227,499 Allendorf Jan. 14, 1941 2,349,778 Teplow May 23, 1944