Measuring and testing – Vibration – Vibrator
Patent
1992-03-23
1994-10-04
Williams, Hezron E.
Measuring and testing
Vibration
Vibrator
B06B 100
Patent
active
053515455
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to electromagnetic vibration generators, sometimes known in the art as shakers, which are employed for the vibration testing of components, apparatus and equipment in numerous branches of industry and research. Such electromagnetic vibration generators basically consist of an armature which is suspended from a rigid body or stator and having a coil carried by the armature located in an air gap in the stator. A D.C. magnetic field is generated across the air gap either by permanent magnets or electromagnets and when an alternating current is fed through the armature coil, the armature is caused to vibrate along its axis at the frequency of the applied alternating current. The armature is mounted on bearings and has a plurality of peripheral suspension members disposed around it which center the armature in the air gap and allow free movement along its axis of vibration but which impose a high stiffness to any lateral movement of the armature normal to its axis of vibration. An article to be vibration tested may be placed directly on top of the armature or on a work table carried by the armature when the vibration testing is to be carried out in the vertical mode, or the article to be tested may be placed on a horizontal slip table coupled to the armature when the vibration testing is to be carried out in the horizontal mode, as is well known in the art.
In one known vibration generator the peripheral suspension members each consist of a flexure member in the form of one or more leaves of polypropylene which are rigidly connected at one end to the armature and anchored at the other end to the stator via a U-shaped bracket. Although such a flexible suspension structure has been found to be adequate when the vibrational stroke of the armature is within certain limits which have hitherto been accepted by users; there is now a requirement for a longer vibrational stroke of the armature. As a result, premature failure of the bracket can occur due to fatigue since it cannot sustain the increased flexing load imposed upon it by the larger vibrational stroke of the armature.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an electromagnetic vibration generator having an armature suspended from a stator, in which the armature for transmitting the vibrations generated to an article to be vibrated is suspended at its periphery by a plurality of circumferentially spaced flexure members each connected at their outer end to the stator by means of an anchoring bracket comprising a floating part connected to the outer end of the flexure member, a stationary part connected to the stator and at least one resilient member disposed between and located with respect to said parts, characterised in that the parts of the bracket are provided with recesses in each of which is located a part of a resilient member of elongate form and the recesses are blind, that is to say have closed ends, so as to reduce the tendency of the material of the resilient member or members to migrate during operation of the vibration generator as well as to provide rotational stiffness for the complete armature suspension assembly.
The resilience of the bracket is such that it can withstand foreshortening of the flexure member as it flexes during movement of the armature along its axis of vibration whilst providing stiffness in the direction of torsional movement of the armature about the said axis.
Preferably each bracket comprises a central rigid floating part disposed between two outer rigid stationary parts and at least one resilient member is arranged between either side of the floating part and the adjacent stationary part.
In one embodiment, each bracket comprises four elongate resilient members arranged two on either side of the central floating part, each resilient member being located by a blind recess in the floating part and a blind recess in the adjacent rigid part. Each bracket is connected to the flexure member such that the lengths of the resilient
REFERENCES:
patent: 3062041 (1962-11-01), Spodnewski
patent: 3123728 (1964-03-01), Kreiskorte
patent: 3529188 (1970-09-01), Gearing
patent: 4715229 (1987-12-01), Butts
Ling Dynamic Systems Ltd.
Oda Christine K.
Williams Hezron E.
LandOfFree
Electromagnetic vibration generators does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electromagnetic vibration generators, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic vibration generators will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-573881