FR2622291A1 - ELECTROMAGNETIC VIBRATORS - Google Patents

Abstract

The invention relates to a head expander for attachment to the head of the armature of an electromagnetic vibration generator, which has a generally frustoconical shape and consists of an upper support plate or work platform. 1 at its largest end, and a lower plate 2 at its smallest end. A honeycomb-type cellular structure 3 extends between the plates 1 and 2, the axis of the cells being normal to the plane of the plates, and a plurality of rigid-walled tubes 4, load transmitters, extend to through the cell structure, parallel to the axis of the cells. Cell structure 3 has a layered or sandwich form, each cell layer being separated from its adjoining layer (s) by a separator sheet. A cover or skin 8, for the outer side wall, envelops the cell structure 3. The invention finds its main application in machines for testing vibrations.

Description

ELECTROMAGNETIC VIBRATORS

  The present invention relates to electromagnetic vibration generators, also known as

  name of "vibrators", which produce a vibrating environment

  simulated roof and which are used for vibration testing of articles such as components, devices and

equipment.

  These vibration generators are basically

  consisting of an armature structure comprising a coil

  ment, which is suspended in the air gap of a magnetic circuit defined by the stator, or body, of the vibration generator. An excitation of the armature winding at a

  selected frequency causes a vibration of the structure

  armature at this frequency, so that an article connected to, or supported by, the armature is subjected to

this vibration.

  So that the vibration tests can be carried out along a vertical axis or along a horizontal axis, the body of the vibrator is generally mounted on pivots so as to be able to pivot between a vertical position and a horizontal position. For vibration tests along a horizontal axis, the armature of the vibration generator is usually connected to a sliding table or another

  support on which the article under test is fixed.

  For vibration tests along a vertical axis

  cal, it is possible to support small direct items

  head on the armature. However, as the effective area of the armature head is relatively small, it is known to attach to an armature what is called a head enlarger. It is a type of platform, which rests on the head of the armature and is fixed to the latter, so as to provide a larger support area, which may

  receive larger test items.

  The constructions of the current state of the art,

  with regard to the head expander, are

  solid metal, cast or shaped and, well

  that they provide the required increase in the work area

  vail to support large items

  sions tested, they suffer from the disadvantage of having a large mass, which obviously affects

  the performance of the vibration generator.

  The object of the present invention is to provide an improved construction of a head enlarger, having a lower mass, and therefore requiring, for its excitation, a

weaker vibrator thrust.

  According to the present invention, a head expander, intended to be fixed to the head of the armature of a generator

  electromagnetic vibrations, includes a cellular structure

  the sheet fixed to a support surface intended to support an article under test, said cellular structure ensuring structural rigidity between the head of the armature and the

support surface.

  According to one embodiment of the invention, the cell structure generally has a honeycomb structure, the cells being normally arranged on the support surface so as to extend vertically when the head enlarger is in position walking, fixed

to an armature.

  Alternatively, instead of being a honeycomb structure, the cell structure may have a mesh structure, and for example cells may have a

rectangular cross section.

  According to a preferred embodiment of the invention,

  a plurality of rigid-walled tubes extend through

  towards the cellular structure parallel to the axis of the cells

  and are used to transmit the charge from the vibrator to the support surface. These tubes provide the locations

  intended to receive screws or bolts, by means of

  which the head expander is attached to the armature head.

  The cell structure can be stratified, i.e.

  say to be of the sandwich type, with separating sheets arranged parallel to the support surface and separating from each other the contiguous layers of the cellular structure. In a preferred embodiment of the invention, the head enlarger has a generally frusto-conical shape, the larger end forming the support surface, or working platform, on which a test article is fixed. , the small end being adapted so as to

  be adjusted to the head of the vibrator armature.

  The invention will now be explained in more detail by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view, partially exploded, of an embodiment of the head enlarger according to the invention, Figure 2 is a half view in section, on a large scale, showing the structure of the head enlarger, in more detail, and Figure 3 is a schematic view showing the head enlarger attached to an electromagnetic vibration generator.

  With reference to the drawings, the head enlarger illus-

  very has a generally frustoconical shape and comprises an upper support plate, or working platform 1, at its largest end, and a lower plate 2 at its small end. A cellular structure 3, of the honeycomb type, extends between the plates 1 and 2, the axis of the cells being normal to the plane of the plates, a plurality of

  rigid-walled tubes 4, load transmitters, extend

  - through the cellular structure, parallel to

the axis of the cells.

  The structure is shown in more detail in Figure 2, which shows that the cell structure 3 has a laminate or sandwich shape, each cell layer 3 '

  being separated from its immediately contiguous layer (s)

  forwards by a separation sheet 5. The tubes transmits-

  load heads 4 are located, at their upper end 4a and at their lower end 4b, respectively in the upper support plate 1 and in the lower plate 2, and they also serve as locations for the bolts or screws 6 using which the head expander is fixed to the armature head 7. A cover, or skin 8, for the outer side wall, is provided to wrap the structure

cell 3.

  Figure 3 illustrates the head enlarger attached to the

  armature head 7 of an electro-vibration generator

  magnetic whose stator or body 9 is mounted on pivots 10 in a support frame 11. As can be seen, the vibration generator is oriented so as to vibrate along a vertical axis, to transmit vibrations to a

  article 12 fixed to the working platform 1 arranged horizontally

  horizontally. In the embodiment described, the plates 1 and 2, and the cellular structure 3 are preferably made of aluminum or an aluminum alloy, while the charge transmitting tubes 4 are preferably tubes made of

carbon fibers.

  The head expander is constructed by forming the struc-

  sandwich the cell layers 3 ′ and the separation plates 5, the assembly then being cut out to give a frustoconical shape. The holes for receiving the carbon fiber tubes 4 are then machined, and the tubes and the honeycomb sandwich are assembled on the upper aluminum plate 1 and on the lower plate 2, using a adhesive based on an epoxy resin at the interfaces of the tubes, the honeycomb structure and the plates. The whole is then cooked in the

  required temperature and vacuum. Finally, the aluminum skin

nium 8 is glued to the structure.

  If desired, the head expander can also be constructed from different materials. For example, the cell structure could be steel, polyamide or fiberglass, and the work platform 1 could

  be made of a fabric bound by a resin, or glass fibers.

  As for the charge transmitting tubes 4, they could also be made of steel or aluminum, although carbon fibers are preferred, due to better

stiffness / weight ratio.

  Of course, the invention is not limited to the examples

  ples of realization described above and represented, from

  shooting which may provide other modes and other embodiments, without departing from the scope of the invention. In particular, the cell structure has not

  need to have a sandwich structure. In addition, one can use

  read instead of a honeycomb structure

  different arrangement forms, for example a grid.

  Those skilled in the art will understand that the overall form of the

  structure may be different from a frustoconical shape.

Claims (12)

Claims   1. Head enlarger, for attachment to the head of the armature of an electromagnetic vibration generator, characterized in that it comprises a cellular structure (3) fixed to a support surface (1) intended to support   an article (12) to be tested, said cellular structure provided   rant structural rigidity between the armature head (7) and the support surface.   2. Head enlarger according to claim 1, charac-   terized in that the cell structure has a structure   general honeycomb type, whose cells are dis-   normally placed on the support surface so as to extend vertically when the head expander   found in the running position fixed to an armature.   3. Head enlarger according to claim 1, charac-   terized in that the cellular structure is of the grill type   age. 4. Head enlarger according to claim 3, in   which cells have a rectangular cross section laire.   5. Head enlarger according to any one of   Claims 1 to 4, characterized in that a plurality of   rigid-walled tubes (4) extend through the cell structure, parallel to the axis of the cells, and serve to   transmit the load from the vibration generator to the support face.   6. Head expander according to claim 5, in which the tubes provide the locations intended for   receive screws or bolts by means of which the   The head is attached to the armature head.   7. Head enlarger according to any one of   Claims 1 to 6, characterized in that the structure   The cell is laminated, separating sheets (5) being arranged parallel to the support surface and separating the immediately adjacent layers from the cell structure. 8. Head enlarger according to any one of   previous claims, characterized in that the structure   cell ture is wrapped in a blanket or skin   (8) for the outer side wall.   9. Head enlarger according to any one of   Claims 1 to 8, characterized in that the structure   cell is made of aluminum or an aluminum alloy. 10. Head enlarger according to any one of   Claims 5 to 9, characterized in that the tubes with   rigid walls are made of carbon fibers.   11. Head enlarger according to any one of   claims 1 to 10, characterized in that it has a shape   generally frusto-conical, the larger end forming the support surface or work platform to which a test article is attached, the smaller end being adapted to fit the head of   the armature of the vibration generator.   12. Compressed electromagnetic vibration generator   armature head, characterized in that an enlarger   head according to any one of claims 1 to 11 y is fixed.