Note: Descriptions are shown in the official language in which they were submitted.
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The present invent:ion re]ates to an improved structure of an eccentric
mass to be used in vibrators such as material tampi.ng devices, pile
drivers, vibratin~ tabl.es, and generel.]y vibrators for the conveying of
small ar~ic].es and the ].ike.
In these device tbe general. structure comprises supporting members in
which bearing are included, the ]atter requiring a continuous
lubrication.
This ].ubrication can be of two types, one the so-called by fluttering
and the other that by nebu].iz~tion .
General].y the nebu].ized ].ubrication consists in the throwing of oil
sprays onto the bearings, col]ecting the oil excess in a recovery basin
and returning the oi]. from the basin to the spraying no7zles by means of
a pump3 this type of ]ubrication is on].y performed in free atmosphere.
The lubrication by f]uttering , which can be carried out both in a free
atmosphere and under vacuum , generally consists in driving into rotation
an eccentric mass w:ithin an oi]. container, the oil bein~ thrown by the
centrifugal force towards the periphery of the basin, wherein sma].l
channe].s are provided by which the oi]. is conveyed towards the bearings
and then co].lected onto the bottom of the same basin.
Several types of eccentric masses are known.
A first type consists of a meta]. semicircular disk (for instance an iron
disk) driven into rotation around its axis, whereby at each half turn an
impact against the oil mass occurs, the ].atter being pushed a~ainst the
walls of the basin. This impact is generally rather strong, although
being dependent on the diameter of the disk, on the thickness thereof and
on the viscosity of the oil3 thus this type Or eccentric mass has its use
restricted to the range of the smal.l powers.
In order to enl.arge the app].ication range of the eccentric mass, it has
been proposed to enc].ose the semicircular dislc within a metal
semicircu]ar housing, having ]ow thickness ~such as for example a case of
metal sheet).
Although by this expedient the above mentioned impact wi.th the oil is
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avoided and an oi:l elltr~inlllcllt effect occurs, however the we]ding 'seams
and/or the riveted joints of the outer case remain the weak point of the
assembly, with serious possibilities of breakages and consequent
detachment of the c~se from the interna]. semicircu].ar disk.
Anotller type of eccentric m~ss consists of a disk of circu]ar shape in
which, by milling, the semicircu].ar shape of the eccentric mass is formed
whereby the previously described rotation is created again, but in a
monolithic form.
In this way the strong impacts of the above cited first case are reduced
and obviously the detachment of the second cited case cannot take place,
but the force that the mass may apply during its rotation is relevantly
].imited. .
The presence of a f].uttering effect causes the number of rotations of the
eccentric mass to be compu].sori].y reduced, with the attendant reduction
of the entrainment effect with respect to the secondly cited case.
The purpose of the present invention is that of providing a solution
overcoming the above mentioned drawbacks in terms of impact and
detachment of the components of the eccentric mass, together with a
greater efficacy of displacement of the oil mass against the peripheral
wal]. of the basin (without an exceedingly high consumption of energy).
Thus the object of the present inventlon is an improved structure of the
eccentric mass comprising a rmetal disk (generally a steel disk) rotating
around its central axis, characterized in that said disk consists of a
material having a determined specific gravity and is provided with at
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].east a cavity ].ocated in a radial].y more externa] area with respect to
said axis, said cavity housing at least one pad of a material having
specific gravity different from that of said materia]. of said disk.
According to a first preferred embodiment of the present invention said
disk has at least two cavities respectively located at opposed zones with
respect to a symmetry axis of said disk, said symmetry axis being
perpendicular to said rotation axis, one of said opposed cavities housing
a pad or p].ug of a material having specific ~ravity higher than that of
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the material. of s~id d:i.sk or of a matcria] having specific gravity,].ower
than that of the material -forming said disk.
~ccording: to another embodiment of the present invention, said disk has
at ~.east two cavities respective]y located at opposed zones with respect
to a symmetry axis perpendicul.ar to said centra]. axis, at :Least one of
said cavities housing a pad or p].ug of a material having specific gravity
higher than that of the materia.]. forming said disk, and at least one of :~
the cavities located in the opposed zone with respect to said symmetry
axis housing a pad or p~ug of a materia]. having specific gravity ].ower
than that of the m~terial forming said disk.
According to a further preferred embodiment of the present invention said
disk is provided with a number of cavities located along a circular. crown
coaxia]. with rcspect to said disk, at ].east one of the cavities located
from one side with respect to a symmetry axis of said disk, perpendicular
to said rotation axis, housing at ].east a pad or plug of a material
having specific gravity higher than that of the material forming said
disk, and at ]east one of the said cavities located at the opposite si.de
of said symmetry axis housing a pad or plug of a material havin~ specific
gravitiy ].ower than that of the materia]. forming said disk.
Said cavities have preferab]y circu].ar shape or, al.ternatively, consist
of circular through ho]es.
Still preferably said p].ugs have the same shape as that of sai.d cavi~ies
and are permanently forced within said cavities.
Preferab].y said heavier pads or p].ugs are of a material selected among .
].ead, wolfram and their alloys.
Still pre~erab].y said ].i~hter pads or p].ugs are of a p].astic material
se].ected among nyl.on, pol.yethylene therephtalate and their mixtures. ~:
Thé specific features and advantages of the present invention shall
appear more c].ear].y ~rom the fo].lowing description of a preferred
embodiment, having illustrative but non limiting purpose, with reference
to the accompanying drawings, in which: - ~
fig. 1 is a perspective view of the structure of eccentric mass according : : .
,,.. :,: .: . , ., , . . .. " ",. . ,: , . . , , . . . : .;, . ......... .. . ..
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to the present invention;
fig. 2 is a plan vie~ of~the eccentric mass structure of fi~
Referring to the figs. I and 2, reference 10 indicated generical].y the
structure of the eccentric mass; it consists of a disk 11 havin~ a
certain thickness, of a meta] materia]. such as steel, iron , cast iron :and aluminium or even of a plastic material resistant to the oil action. :
The disk 11 having essentia].]y circular shape is rotatable around its . .: .
central axis 11 and is manufactured so as to be substantially dynamically
balanced, owing to the profi]e thereof, without the presence of .:.
particular hetero~eneous masses in its body outward]y of its rotation ~.
axis. :
The disk 1I has si.x ho]es 13, the axes of which lie on a circular crown
14, the axis of which is coincident with that of said disk~ the diameter
of the crown and the diameter of the holes are selected so that a
re].evant space S exists between the most outer end of each hole and the
circumference forming the border line of the disk. :
At the center of the disk the device for the splining of the disk to the
rotation shaft (not shown) is provided, but no further comments shall be .
given, since it is within the reac~l of the man skilled in this ar~t.
Taking as the symmetry axis of the disk 11 the axis XX, the three holes
15, 16 and 17, 1aying in the ]ower part with respect to the said ..
symmmetry axis, house respectively the pads 18, 19 and 20 of cylindrical
shape and of a materia]. having specific ~ravity higher than that of the
material of the disk l1, preferbaly leadj wolfram, or an a].loy containing ~ :-
at least one of said metals. :-
The three ho].es 21, 22 and 23, ~.aying in the upper part with respect to
the said symmetry axis, house respectivel.y the p].u~s 24, 25 and 26 stil].
of cylindriea.]. shape and of a materia]. havin~ specifie ~ravity lower than ; `
that of the materia]. of the disk 11, preferab].y a plastie materia]. like
nylon (having specific gravity 1.2) and polyethy]ene terephtalate, or ~ ..
compounds of these plastic materia]s.
The pads and the plu~s have a size such that they are forced within the
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respective holes, thus bei.Il~ perIllanent]y and certainly bl.ocked thereinto.
~or further safety the screws 27 c~n be added, actin~ a~ainst the pads
and the p]ugs in a radial direction.
According to a particul.ar embodiment the hol.es 13 might lay along two
l.ines para].le]. to the symmetry axis XX, at one side and at the other side
of said axis.
The holes 13 may be in a number different from six, as described, and
mi~ht even consist of only one hol.e ].ocated at one side with respect to
the symmetry axis XX and spaced therefrom, said hole being provided with
a lead pad or proper si%e: in this case an eccentric mass would be
obtained suitable for some uses.
The addition of a ho~.e prov:ided with a nyl.on pl.ug at the opposite zone
and ~t the same distll-ce from the symInctry axis may enhance the
performances of the eccentric mass.
The holes may have different shapes besides the above described
cylindrical one3 for example they can be blind cavities, have triangular,
square, poly~onal. or slice or other shape3 of course the pads and plu~s
shal.l have like shapes.
The pads/plugs, instead of being forced, can be glued, when it is
consistent with the materia~.s being employed, a].though this type of
attachment might to sometimes economical.l.y less advanta~eous than the
forcin~.
Alternatively the hol.es and the related pads/plu~s might be screw
threaded and assembled by screwin~, al.thou~h in particular cases of
particularly heavy uses, s]ight re].ative, undesired displacements of the
assemb~.ed elements mi~ht occur.
The shape of the pads/p].u~s must be consistent with that of the
hol.es/cavity of the disk, but it does not mean that their shapes must be
identical3 for example whilst the shape of the holes/cavities may be
cy].indrical, the shape of the correspondin~ pads/p].ugs may be partial]y
cy].indrical. with side planar surfaces, as indicated by the reference 28
with dashed lines in fig. 2.
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The structure of eccentric mass accordin~ to the present invention and
above descr.ibed with respect to a preferred embodiment thereof, to~ether
with some different construction alternatives, does comp]ete]y fu].fil]
the purposes sought for, namel.y to improve the performances of the ].ike
structures known in the prior art.
As a matter of fact the described structure of eccentric mass,
consisting of an essentia].].y circu].ar disk (and possib].y s].i~htly
e].].iptical) has no impact effects on the ]iquid to be disp].aced a~ainst
the walls of the basin; on the contrary on]y ]iquid entrainment effects
are shown therefrom: that means that this structure is suitable also for
high power vibrators, whereby the use fie].d is broadened.
More particu].ar].y the structure of the invention is capab].e of enduring
without prob].ems a hi~her number of rotations of the disk and an
eccentric mass is obtained re].evant].y ~reater than those .of the prior
art, with the resu].tin~ ~reater efficacy of displacement of the ].iquid
mass3 alternative].y the efficacy bein~ the same, the structure is
rei.evantly ].ess encumberin~.
Furthermore the prob].ems of detachment of the component e].ements are no
].on~er present (as in the case of the eccentric mass housed in a case)3
the structure of~the present invention as a matter of fact consists of
massive members secured to each other in a quite fi~ed manner, whereby an
essential].y compact structure resu]ts; consequent].y the structure of the
lnVentiOn can be effective].y used a].so in the case of vibratin~ devices
operatin~ under the most serious conditions, both in terms of frequency
~nd in terms of vi.~rat:i.ons.
Not negl.i~ib].e is a].so the fea.ture of the simp].icity of the eccentric
mass structure by which the manufactin~ becomes ea.sy and ready, thus
positively affecting the industrial. production costs.
~].thougb the eccentric mass structure accordi.n~ to the present invention
has been described with reference to a preferred embodiment and to
several a].ternative variations, possib].e further modifications thereof
are considered as fa].].ing within the main concept characterizing the
present invention.
