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Патент USA US2404710

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July 23, 1946.
Filed July 2, 1943
7340.17.’ Wm
A 77'0R/VEV
Patented July 23, 1946
Stanley Isaiah Hitchcock, London, England
Application July 2, 1943, Serial No. 493,238
In Great Britain July 14, 1942
4 Claims.
(Cl. 175-367)
ble comprises members 28 composed of soft iron
or other magnetic material having a high ini
tial permeability and intervening spacing mem
bers 25 or non-magnetic material, the members
28 and ‘it being enclosed within a surrounding
frame 32 which may conveniently be die-cast
It has been found in the course of experiments
that if the poles of a permanent magnet are
joined by a soft iron or other member of mag
from a suitable non-magnetic material.
The table is slidably mounted on a base like
wise built up of members 39 of soft iron or other
This invention relates to permanent magnet
structures wherein a permanent magnet is asso
ciated with a soft iron or other armature mem
ber separated from the pole faces of the magnet
by an intervening air gap or layer of insulating
netic material having a high initial permeability 10 magnetic material having a high initial perme
such as “Mu-metal” which is divided up into sec
ability and intervening non-magnetic spacing
members 3%, the members 30 and 3! being also
tions, the sections being separated by non-mag
enclosed within a surrounding frame 32a com
netic material, that the lines of magnetic force
posed of non-magnetic material and formed for
will pass through the sections, although the sec~
tic-ns with the intervening layers of non-magnetic 15 example by a die-casting process. The members
and so may if desired be of laminated con
material will have a higher reluctance than in
the member comprised of a single piece of soft
Located within the base is a permanent mag
iron or other magnetic material.
net 33 the end faces of which adjacent the poles
It is proposed therefore in accordance with the
present invention to provide a permanent mag 20 contact the adjacent members 38. The upper,
lower and lateral faces of the magnet may either
net with such a ?ux path, and to construct an
be in contact with the members 38 or separated
other member for use with such a magnet, in a
therefrom by intervening spacing members of
similar manner, said other member being sepa
non-magnetic material or alternatively separat
rated from the sectioned member providing the
ed by an intervening air gap. The members 30
?ux path by an air gap or a layer of non-mag
and 3| and permanent magnet are contained
netic material, said other member and perma
within a surrounding frame 3241 which may be
nent magnet being relatively movable to permit
conveniently die-cast from a non-magnetic ma
of the sections comprising the flux path and the
other member to lie opposite one another or to
The upper member or table when not in opera
occupy a position in which they lie in staggered
tion occupies the position shown in the ?gure
relationship. In this way the degree of attrac
in which position the members 28 of the table in
tive force between the permanent magnet and
the absence of the workpiece ful?ll the function
the other member can be varied as it has been
of a keeper. the members 28 absorbing the un
found as a result of experiments, that when the
wanted magnetic ?ux, the lines of magnetic flux
various sections are oppositely arranged the lines
following a zig-zag path of least reluctance
of magnetic force pass mainly through the flux
through the members 353 and 28, the lines of mag
path, the attractive force exerted on the other
netic ?ux being con?ned to the inner ends of
member being nil or small whilst when the sec
the members 23. When the table is moved into a
tions occupy a staggered position the lines of
magnetic force take a zig-zag path. through the 40 position in which the members 28 and 3B are in
alignment, the lines of magnetic ?ux emanating
?ux path and the other member, the attractive
from the poles of the magnet 33 pass upwardly
force being then materially increased.
through the aligned members 38 and 23 into the
In order that the said invention may be clearly
understood and readily carried into effect, the
workpiece thus exerting a powerful attractive
same will now be further described with refer
ence to the accompanying drawing, wherein the
single ?gure is a sectional view disclosing a mag
' force on the workpiece and maintaining it in
position on the table. When it is desired to in
crease the magnetic attraction to maintain the
workpiece in position, the table is moved into a
position in which the parts 25 and ?il are disposed
The application of this invention that is 50 in alignment, movement being effected by the
lever 34 which is pivotally connected with the
shown in the ?gure comprises a magnetic bench
base at the point 35 and pivotally connected to
which includes a base and an upper member or
the upper part or table at the point 35.
table on which a workpiece or workpieces can be
What I claim and desire to secure by Letters
placed and retained ?rmly in position thereon
during a machining or other operation. The ta 65 Patent of the United States is:
netic bench constructed in accordance with the
present invention.
1. A permanent magnet structure comprising
a permanent magnet having a flux leakage path
bers of high initial permeability separated by
intervening members of non-magnetic material,
between its poles, and an armature member for
use therewith said flux leakage path and arma
one of said elements overlying the other with the
members of both elements extending in the same
ture member being constructed in a similar man
direction, one of said elements containing a per
her and being built up of a series of members
manent maget, and means for imparting move
composed of soft iron or other magnetic material
having a high initial permeability and interven
ing spacing members of non-magnetic material,
members of high initial permeability of said ele
ment to and from staggered position with respect
ment to the other of said elements to shift the
and means for moving said armature member
to the like members of the other element to
thereby Vary the density of the magnetic ?eld
endwise from a position in which the soft iron
members of the armature and flux leakage path
existing between the two elements.
4. A magnetic workbench comprising a table
lie opposite or in line into a position in which
the parts occupy a‘ staggered position and vice
for the reception of the Work, and a base, said
versa, for the purpose of controlling the pas- 15 table and said base each including a series of
sage of the lines of magnetic force emanating
members of high permeability material sepa~
from the permanent magnet, through the arma“
rated by intervening members of non-magnetic
ture member, and thereby increasing or decreas
material, the members of said table and said base
ing the attractive force between the permanent
extending in the same direction, the members
magnet and its associated armature member.
20 included in said base enclosing a permanent mag~
2. A magnetic Workbench comprising an upper
net, the
each enclosed
included within
in said abase
member or table and a lower member or base,
the table including a series of members com
frame of non~magnetic material, and means for
posed of soft iron or other magentic material
imparting movement to said table in a direction
having a high initial permeability and separated
at right-angles to the length of said members to
by intervening members of non-magnetic mate
move the members included in said table into
and out of staggered relationship with regard to
rial, the lower member likewise comprising a se—
ries of soft iron or like members with interven
the members included in said base to thereby
ing non-magnetic spacing members, the lower
control the liners of magnetic ?ux emanating from
member containing a permanent magnet and
the permanent magnet, the members when in line
means for imparting relative movement to the
permitting the maximum number of lines of mag
upper and lower members to bring the soft iron or
netic ?ux to pass through the work, and the
like members in the upper and lower members
work to be held ?rmly on the table, the members
into a position in which they occupy a relatively
when in a staggered position providing an alter
staggered postion, or an inline position for the 35 native path for the lines of magnetic ?ux of a
purpose of causing the permanent magnet to exert
lower reluctance than that which they would
a suf?ciently high degree of magnetic attraction
have to take to pass through the work, the num
on a workpiece placed on the table to retain it in
ber of lines of magnetic flux passing through
position thereon, or, to so reduce the magnetic
the work being thus reduced to a minimum,
attraction to permit of the workpieces removal. 40 thereby enabling the work to be removed from
3. A permanent magnet structure comprising
the table without dif?culty.
two elements each including a like series of mem
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