US 3418538 A
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T. ROMAN TS WH Dec. 24, 1968 3,418,538
DEVICE HAVING w PAR ICH A BE ORIENTED IN P ETERMINED POS CNS 2 Sheets-Sheet 1 Filed April 26, 1966 FIG] THEODORE ROMAN g, n ATTORNEYS Dec. 24, 1968 T. ROMAN 3,418,533
DEVICE HAVING TWO PARTS WH ORIENTED IN PREDETERMINED ICH CAN BE POSITIONS 2 Sheets-Sheet 2 Filed April 26, 1966 FIG.9
THEODORE ROMAN \NVENTDR ATTO RNEYS United States Patent 3,418,538 DEVICE HAVING TWO PARTS WHICH CAN BE ORIENTED IN PREDETERMINED POSITIONS Theodore Roman, Neueuhof, Switzerland, assignor to Oerlikon Engineering Company, a Swiss corporation Filed Apr. 26, 1966, Ser. No. 545,421 Claims priority, application Switzerland, May 11, 1965, 6,540/65 7 Claims. (Cl. 317123) ABSTRACT OF THE DISCLOSURE Adjustable magnet having two spaced pole members defining gap between them. At least one pole member includes wedge-shaped rotatable support and a wedgeshaped pole piece rotatable with respect to the support. Axes of rotation of support and pole piece arranged at an angle to each other. Support and pole piece may be rotated by worm gear and worm, or by coaxial shafts. Automatic rotary adjustment of support and pole piece may be provided.
This invention relates generally to an apparatus having two parts which can be aligned in predetermined positions, and more particularly to an apparatus comprising adjacent magnet polar surfaces which can be aligned with respect to one another.
In the use of magnets for research purposes, particularly with magnets used for measurements in nuclear resonance spectroscopy, the uniformity of the magnetic field created between the magnetic poles must be of the highest precision. On the other hand, some specific physical measurements require certain distributions of the magnetic field which are not uniform. The attainment of both of these conditions requires precisely determined geometric measurements of the air gap between the magnetic poles.
For example, the relation:
shows that the magnetic flux density or induction B in the air gap of a width 6 at a given excitation or circulation 0 and at constant value of the permeability ,u in vacuum or air, is actually dependent on the spacing between the two polar surfaces. Thus, a constant intensity of the magnetic field, i.e., a constant magnetic reluctance, between the two polar surfaces must be accompanied by a constant spacing between the polar surfaces.
It is known that measurements indicated by the known constructions undergo changes as a result of the action of the magnetic attraction forces between the magnetic surfaces which deforms portions of the magnetic yoke. This deformation is a function of the excitation of the magnet and the width of the air gap. The refraction forces, which can be calculated from the relation:
B 2 F A (5,000)
can reach considerable values.
In the above equation,
F=force in kg.; A=effective cross section in cm. and B=intensity of magnetic field in gauss.
For example, a field of 25,000 gauss at an effective cross sectional area of 300 cm. (19.5 cm. diameter), produces a magnetic force of 7.5 tons. A field of 35,000 gauss at this cross sectional area produces a magnetic force of tons.
With a yoke which is arranged unsymrnetrically to the axis of the field, the above mentioned changes, due to the unsymmetrical construction, produce a reciprocal inclination of the polar surfaces which were originally in parallel. This inclination must be compensated for to provide the necessary magnetic field uniformity. The order of magnitude of the required precision of the pole inclination is illustrated by the following example. If B is the average value of the induction in an air gap of a width 5 and if B is the average value in an air gap of a width 6 then If it is assumed that B =B +AB and that 5 =5 A6 then this relation becomes:
mm B 5 If a field uniformity of, for example AB/B=l0- is required, this requires with an air gap of, for example, 5:50 min, an absolute precision of at least However, with the above mentioned magnetic attractions, the changes of the polar distance far exceed this value.
One known manner of compensating for the deformation of the polar surfaces consists in oppositely orienting the inclination of the polar surfaces of an unexcited magnet. However, this method has the disadvantage that a precise compensation is possible only for an accurately determined excitation, i.e., for a precisely known current intensity and air gap of known dimension. However, in general, compensation for any desired load would be required.
A further possibility of correcting for the oppositely oriented inclination of the polar surfaces, is a symmetrically closed design of the magnetic yoke. It is obvious that in this type of arrangement, the polar surfaces are subject only to a parallel shifting along the axis of the field. This is true despite the deformation of parts of the yoke as a result of the action of the magnetic attraction forces. For this reason, magnets of this type of design are widely used. However, these magnets are subject to several noticeable disadvantages. For example, the second short-circuit yoke of a symmetrical magnet greatly reduces the accessibility to the air gap between the magnetic poles, thus resulting in the need for auxiliary equipment. A further disadvantage of the symmetrical magnets is that the side yokes can be shifted to achieve a maximum range of adjustment of the pole spacing, only by the use of complex and costly equipment. In some cases the pole spacing cannot be shifted at all. In contrast to this, the shifting of the side yokes in unsymmetrical magnets is readily achieved.
It is therefore an object of the present invention to eliminate the disadvantages of the known devices. In accordance with the present invention, an apparatus is provided in which at least one of the two parts can be rotated on its base in order to facilitate continuous alignment of the two parts. The axis of rotation of the rotating part forms an angle with the main axis of symmetry of the apparatus which may vary between 0 and The invention is illustrated by way of example in the figures shown below. In the figures:
FIG. 1 is a longitudinal section taken through the apparatus, illustrating features of the present invention;
FIGS. 2 and 3 are sectional views of the apparatus shown in FIG. 1, showing the parts in the two extreme positions of inclination;
FIG. 4 is a sectional view of apparatus shown in FIGS. 13, illustrating a worm-gear drive for rotating the parts;
FIG. 5 is a longitudinal section showing another type of drive for the adjustment of the various parts of the apparatus;
FIG. '6 is a view similar to that of FIGS. 2 and 3 illustrating a two-part guard ring;
FIG. 7 is a view similar to FIG. 6 showing an alternative construction;
FIGS. 8 and 9 are sectional views of typical pole pieces which may be employed in the apparatus of FIG. 1; and
FIG. 10 is a wiring diagram of a controlling device for the apparatus, such as that shown in the embodiment of FIG. 4.
The end of a yoke of a magnet, shown in FIG. 1, comprises a fixed or startor part 1 and an intermediate support member 3 of conical shape which can be rotated on the datum plane 28 of the stator part 1. The stator part 1 is provided with a bore 7 into which a cap screw 9 is inserted in order to support the intermediate support member 3 in such a manner that support member 3 can be rotated. A suitable chamber 11 is provided in support member 3 for the insertion of the head of the screw 9. Chamber 11 is closed by means of a stop plate 13 which is fastened to member 3 by screws (not shown). Stop plate 13 also serves as a mounting support for the head of the screw 9. For that magnetic circuit the chamber 11 is bypassed by suitable means.
The axis of screw 9 coincides with the main axis of symmetry 15 of the stator part 1, while the bearing surface 17 of the intermediate support member 3 forms an angle of less than 90 with the main axis of symmetry 15.
Surface 19 of swivel 5 rests (an the bearing surface 17. The axis of rotation 21 of swivel 5 forms an angle ,8 with the main axis of symmetry 15. The swivel 5 is provided with a fastening pin 23, at the end of which is placed a spring washer 25 which is fastened to swivel 5 by a nut 26. In this manner, the swivel 5 is rotatably connected to the intermediate support member 3, so that swivel 5 can be rotated on the intermediate support member 3 about the axis of rotation 21. FIG. 1 shows the end or directional surface 27 in vertical position with respect to the horizontal main. axis of symmetry 15. In FIG. 2, the swivel 5 has been rotated through an angle of 180, around the axis of rotation 21, as compared to the position in FIG. 1, while the position of the intermediate support member 3 is left unchanged. Therefore, it may be seen that the inclination of directional surface 27 may be moved from the vertical with respect to the main axis of symmetry 15, by an angle of up to 2,8.
FIG. 3 shows the other extreme position, in which the intermediate support member 3 is rotated through an angle of 180, while the position of the swivel 5 is maintained as in FIG. 1. Consequently, the angle of inclination of the directional surface 27, with reference to the normal plane is again equal to 2/3. This same orientation of surface 27 can also be obtained if the members 3 and swivel 5 are rotated as a single unit through an angle of 180 from their positions shown in FIG. 1 about the main axis of symmetry 15. In this manner, it is possible that the angular position of the directional surface 27, relative to the main axis of symmetry 15, which was obtained by prior adjustment of the swivel 5 with respect to the intermediate support member 3, can subsequently be oriented in any manner desired. It is therefore possible to orient the directional surface 27 at any angular position over the range of :25, by rotating intermediate support member 3 and/ or swivel 5. It is also possible to obtain a position, in which the directional surface 27 is parallel relative to another plane, for example, the directional surface of the opposite end of the yoke.
FIG. 4 shows a typical construction permitting the adjustment of intermediate support member 3 and swivel 5. The swivel 5 is provided with a worm wheel 31, which is engaged by a worm 32. The worm 32 is supported by a bearing 34. Another worm wheel 36 surrounds the inter mediate support member 3, and is engaged by a worm 37 supported by a bearing 39 secured to stator part 1.
FIG. 5 illustrates another drive, which acts through a hollow shaft 58, disposed within a lateral passageway provided in stator base 28, upon intermediate support member 3, by means of which intermediate support member 3 is caused to rotate with respect to stator base 28. The support member 3 is secured to the hollow shaft 58 by means of set screws 60. The swivel 5 is rotated by means of a solid shaft 62 within the hollow shaft 58. The two shafts 58 and 62 are arranged at an angle [3 with respect to each other, which angle in this case is relatively small. Swivel 5 is also fastened by means of screws to the shaft 62'. The alignment of the support member 3 and swivel 5 relative to the main axis of symmetry 15, corresponding to the axis of the hollow shaft 58, is carried out in a manner analogous to that shown in the embodiments of FIGS. 1-4.
In the embodiment described in FIG. 6, support member 3 and swivel 5 are held together by means of a twopart ring 42 and can be rotated with respect to each other in the manner described above. FIG. 7 shows a similar construction, in which a one-part guard ring 48 is fit over a shoulder flange 46 of the intermediate support member 44 and is bolted to the swivel 5. FIG. 8 shows the manner in which a pole piece 51 can be fastened to the swivel 5 by means of the screw bolts 53. As shown in FIG. 9, the pole piece 57 may be integrally formed as a swivel having an extending fastening pin 23.
The above described embodiments illustrate typical construtcions of a pole piece, or an intermediate support member which is arranged between the pole piece and the actual pole or the yoke of the magnet. The pole piece or the intermediate support member is separated into two parts by means of a plane section which is oriented at an angle [3 to the main axis of symmetry 15, or it may consist of two suitable parts. The two parts obtained in this manner are wedge-shaped so that a rotating motion of one part relative to the other, and a constant support between the adjoining surfaces, such as 17 and 19, causes the two plane sections of each of the parts, which originally had been positioned in parallel, to be placed into any desired angular position. In the same manner, the surfaces which had originally formed a certain angle can be placed into another angular position, such as into a parallel position. The angle ,8 may be selected according to the desired range of adjustment.
The adjustment of the intermediate support member 3 and swivel 5 can be carried out by a worm gear or concentric shafts as described above, or the adjustment may be carried out manually by the use of wrenches.
FIG. 10 shows a wiring diagram of a controlling device by means of which two pole pieces 57, or their polar surfaces, can be adjusted parallel to each other under any desired load in the manner described above, by the rotation of pole pieces 57 with respect to the intermediate support members 3. The rotation is carried out in such a manner that the two polar surfaces may be positioned at a predetermined angle. Assume the polar surfaces are to be positioned perpendicular to the main axis of symmetry 15. For this purpose, a probe 50 is inserted between the two polar surfaces to maintain the two surfaces at the desired position by evaluation of the prevailing magnetic field intensity between the polar surfaces. Probe 50 transmits signals to an indicator 52 which records the actual values of the magnetic field. The actual values recorded at indicator 52, and the theoretical values obtained from a theoretical value indicator 54 are compared at a comparator 56 which adjusts the swivels 57 and/or the intermediate support member 3 of the yoke of the magnet, until the actual values correspond to the theoretical values. The comparator may act, for example, on adjustable links which are designed as Worm gears.
In this manner it is possible to continuously shift simply and suitably two polar surfaces of open magnets into any desired position.
What is claimed is:
1. An adjustable magnet comprising a base, and a pair of magnetic pole members on said base spaced along an axis in opposed relation to define a gap between them, at least one of said members including a Wedge-shaped support rotatably carried by said base, the axis of rotation of said support being coline-ar with said axis extending between said pole members, and a wedge-shaped pole piece rotatably mounted on said support with one of its two converging faces located adjacent to said support member and the other facing the gap, the axis of rotation of said pole piece being perpendicular to the face of said pole piece adjacent to said support member, whereby rotation of said pole piece causes the angle of its other face to vary continuously with respect to said axis extending between said pole members.
2. An adjustable magnet as defined in claim 1 including a worm gwr mounted on said pole piece, and a Worm cooperably engaging said worm gear, said worm being rotatably supported on said support.
3. An adjustable magnet as defined in claim 2 including a second worm 'gear mounted on said support, and a second worm coopenably engaging said second worm gear, said second worm being rotatably supported on said base.
4. An adjustable magnet as defined in claim 1 including a hollow shaft rotatably carried by said base, said support being mounted on said hollow shaft, and a second shaft rotatably arranged within said hollow shaft, said pole piece being mounted on said second shaft.
5. An adjustable magnet as defined in claim 4 wherein the axes of said shafts are arranged at an angle to each other of less than and greater than 0.
6. An adjustable magnet as defined in claim 1 including a probe located within said gap for sensing the magnetic field intensity between said pole members, an indicator responsive to signals received from said probe for transmitting corresponding signals, another indicator for transmitting signals corresponding to a desired theoretical value of magnetic field intensity between said pole members, a comparator for receiving signals from both indicators and producing a signal corresponding to their difference, and means responsive to said comparator signal for rotating said pole piece.
7. An adjustable magnet as defined in claim 6 including means responsive to said comparator for rotating said support.
References Cited UNITED STATES PATENTS 1,312,546 8/1919 Kanasick 335287 2,569,476 10/1951 Landils et al 336133 X 3,089,066 5/1963 Uc et a1. 335287 X 3,223,897 12/1965 Sullivan 335-298 FOREIGN PATENTS 151,858 12/1937 Austria.
LEE T. HIX, Primary Examiner.
U.S. Cl. 317262; 340421; 324.5, 43; 335-298; 336-432