Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention is based on improvements in permanent
magnet systems for adhesion purposes, particularly in regard to .
a clamping plate of the described kina, the cover plate, insofar
as its magnetic adhesion pxoperties are concerned. In the
improved constructionl the cover plate is provided with holes or
l perforations, hereafter described in detail. A further adYanta-
¦~geous design of the cover plate involves filling the holes with a
jnon-magneticall~ conductive material.
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¦! As a result of the holes which~ advantageously, are
l~distributed over at least most of, or a distinctly substantial
¦Ipart of, the area of entire adhesive surface of the cover plate
~and have a size which is synchronized with the size of the
¦¦adhesive objects, the magnetic stray field existing ad]acent or
beside the magnetic short circuit becomes more intensive, due to
the fact that the magnetic lines of force must pass through a
labyrinth formed by the bridges caused by the holes or perfora-
tions and discharge at the edge of the holes or perforations in
concentrated form. Thus, powerful individual magnetic stray
fields form, in contrast with a cover plate having an imperforate
or closed surface, which are distributed practically uniformly
over the entire adhesion surface, as far as the center of gravity
is concerned.
The cover plate may be of any reasonably practical
thickness, that is to say, lt may be designea thicker than the
known short circuit plates, because the maintaining and the
strength of the magnetic stray field is determined more or less
by the number of the holes or perforations reducing ~he mass of
material of the cover plate. With a thicker cover plate, the
advantage exists that the wear cause~ by prolonged use and occurr-
ing on the surface of t~e cover plate can be repaired by reworking
for example sanding or grinding, and a full replacement plate is
l not required. Conveniently, the thickness of the cover plate may
¦lbe 0.6 to about 2 cm., more ox less.
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In acc~rdance with the present invention
there is provided a permanent magnet system for
a~hesion purposes consisting of individual permanent
magnets inser-ted in-to a ferromagnetic housing and a
cover plate of soft magnetic material covering the
permanent magnets and the housing and used as adhesive
surface, the cover plate seating directly on the pole
surfaces of the permanent magnets and having a thickness
so dimensioned in relation to the magnetic flux of
force of the permanen-t magne-ts that it provides a
maglletic stray field exceeding the magnetic sa-turation,
characterized by the fact that the cove:r plate is
provided with holes.
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~ urther details of the invention are expl~ined below by
Imeans o~ en~odiments exemplified in the drawing, in detail, with
¦particular regard to cons~ructions of the clamping plate.
Fig. 1 shows a schematic VieW of one embodiment of the
present invention showing a form which the clamping plate can
také, with one sidewall eliminated ~o allow for a view into the
housing.
Figs. 2 to 5 show partial sections through different
cover plates with perforations of different designs.
Fig. 6 represents a schematic view of another embodiment
of the invention showiny the clamping plate with one sidewall
partly eliminated to allow for a view into the housing, and with a
different distribution of the perforations on the cover plate.
Fig. 7 shows a schematic view of an embodiment with a
further modified distribution of the perforations in the cover
plate.
The clamplng plate unit consists, in a manner known from
the prior art, of a ferro-magnetic base plate 1 with the permanent
magnets 2 arranged thereon in alternating pole sequence and the
cover plate 3, likewise of ferro-magnetic material, and the lateral
parts 4 r 5 r 6 r 7. The lateral parts 4, S~ 6, 7 which seal the
magnetic system box or housing~like construction preEerably consisl
o ferro-magneticmaterialr like iron, for example~ ~ccording to
~he inVention~ the cover plate 3 is provided with holes 8 distri-
¦buted mainly over its entire surface or in spaced sections or
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arrangements, as described below. These holes are drilled contin-
uously from the top side to the bottom side of the cover plate 3,
or they can be formed in any other suitable manner, for example
by a Laser beam. The magnetic lines of force, thus, flow only
through the bridges 9 between the perforations and thus radiate
with corresponding reinforcement at the externally disposed edges
of the holes 8. Depending on ~he number and the distribution of
the holes 8 in the cover plate 3, a strong magnetic stray ~ield
exists on the surface of the plate which is composed of a multi-'
plicity of individual stray fields.
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The cross-section of the holes 8 can take di~ferent
con~igurations. Thus, as shown in Fig. 2~ the holes 8 have a
cylindrical cross-section. In Fig. 3, the holes 8 have a tapered
configuration. In case of holes 8 with a tapered cross-section
configuration, the tapering may extend from the top side of the
cover plate 3 toward the bottom side as in Fig. 3, or in the
opposite direction as in Fig. 4. With the selected cross-section,
one can determine the thicknesses of the bridges 9 between the
perforations 8 in a difexential manner, and this also applies to
thè prevailing strength of radiation of the magnetic lines of
force at the surface of the cover plate 3. Independen~ly of the
selection of the cross-section ~or the per~orations 8, it is
¦ advisable to fill them with a non-ma~netic material 10, in order
to restore a uniform surface on the cover plate 3. There is
I nothing cri-tical about such non-m~gnetic materials and they may
comprlse non-magnetic metals or alloys such as bxass, or synthetic
or natural non-magnetic materials.
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Instead of havin~ a cylindrical or t:apered cross-section
the perforations 3 can be made to have a cross-section different
from the above r for example, a triangular, qucldrangulax or a
s~ellate cross-section. For achieving the desixed effect accordin~
to the present invention there practically exists no limitation
which the cross-section configuration may not have ~or the perfor-
ations 8. Depending,on a regular or irregular distribution of the
holes 8 on the surface of the cover plate 3, the ~orces of
adhesion may di~fer. With a tight arran~ement of the holes 8 the
magnetic saturation of the cover plate is reduced and the magnetic
stray field, originating from the bridges 9 between the perfora-
tions 8, is increased. Conversely, the magnetic stray field is
reduced when the distance of the perforations 8 from each other lS
increased.
It also may be desirable in certain :instances, as shown
in Fig. 6, to reduce the n~ber of holes 8 in t:he area above the
poles of the magnets 2, and/or to arrange them at larger distances
on the cover plate 3j because here the strongest magnetic radiatio ~ ,
originates from the'poles to the cover plate 3,'and the magnetic
lines of force exiting in a concentrated manner from the poles
coact to the extent where it is necessary to form a magnetic stra~
field effective over the entire surface of the cover plate 3. In
this connection one can also select the embodiment according to
Fig. 7, which contemplates the provision o~ the perfoxa-tions 8 in
the area between the poles of the magnets 2. This aids ln this
area in effecting a reinforced magnetic radiation ana accordingly
brings about an increase in the magnetic force of adhesion.
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f In regard to the thickness of the cover plate 3, there
¦is a relationship therebetween and the distance of the holes 8
from each other. Thus, for an optimal magnetic force o~ adhesion,
the thicker the cover plate 3 the closer together should be the
holes 8; and, conversely, if the thickness of the cover plate 3 is
reduced, the distance from each other of the holes 8 must be .
increased for optimal results.
The magnet system of the present invention can be made
to be connectable and disconnectable in a manner known per se from
prior art.
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