US 2657342 A
Description (OCR text may contain errors)
Oct. 27, 1953 o. E. STEM MAGNETIC PLATE STRUCTURE Filed April 17. 1950 INVENTOR. DONALD E. STEM ATTORNEY Patented Get. 27, 1953 UNITED ATENT OFFICE 2,657,342 MAGNETIC PLATE s'rRuc'rURE Donald E. Stem, san Francisco, Calif. Application April 17, 1950, Serial No; 156,328 1 Claim. (01. sir-159) This invention relates to a magnetic plate structure.
Magnetic plates heretofore used in traps or conduits for foods, grain or the like, included a plate mounted on a frame by belts or similar structures, which with the usual housings thereon, resulted in cracks, crevices and small cavities wherein food or the like substance was lodged and thus produced unsanitary conditions and diminished the effectiveness of the magnetic field.
An object of my invention is to provide a magnetic plate and an integral magnet housing on the plate surrounding the magnets magnetizing said plate so as to form a continuous smooth integral unit without cracks, crevices or the like.
Another object is to provide a magnetic plate unit, which is sanitary, without cracks or crevices, and which can be totally immersed in foods, as for instance on rotating paddles or paddle wheels or agitators, or immersed in tanks or vats or the like, without food particles lodging in the same.
I am aware that some changes may be made in the general arrangements and combinations of the several devices and parts, as well as in the details of the construction thereof without departing from the scope of the present invention as set forth in the following specification, and as defined in the following claim; hence I do not limit my invention to the exact arrangements and combinations of the said device and parts as described in the said specification, nor do I confine myself to the exact details of the construction of the said parts as illustrated in the accompanying drawings.
With the foregoing and other objects in view, which will be made manifest in the following detailed description, reference is had to the accompanying drawings for the illustrative embodiment of the invention, wherein:
Fig. 1 is a perspective view of my magnetic plate unit the top casing being partly broken away to expose to view the packing of the magnets therein.
Fig. 2 is a perspective bottom view of my magnetic plate unit viewing it from upon the collecting plate surface and Fig. 3 is a cross sectional view of my magnetic plate unit.
In carrying out my invention I make use of a plate I made of a pair of spaced strips 2 of magnetic material and a non-magnetic strip 3 in the space between the said magnetic strips 2 being welded together edge to edge into an integral unit and finished to form a single continuous surface 4.
On top of the plate I and straddlingthe nonmagnetic strip 3 is provided a magnet, in the present illustration formed out of a plurality of spaced permanent horseshoe magnets ii so arranged transversely with respect to said strips that the pole pieces I of each magnet 6 are in contact with and engage the respective mag netic strips 3 on the opposite sides of the magnetic strip 3. The magnets 6 are surrounded by a casing 3 which is suitably shaped and rounded and has tapered securing flanges 3 all around suitably flaring into the top surface II of the plate I so that the joining edges of said casing 3 present a continuous smooth surface blending into the top surface I i of the plate i.
Between the magnets 6 and also at the outer side of each magnet ii are provided insulating spacers such as blocks of wood or rubber spacers to positively locate the magnets in the casing and to fill the spaces between the magnets and also between each magnet and the adjacent side of the casing. The top of the casing has on its inside surface a rubber cushion I3 which is pressed upon the magnets when the casing 53 is secured in place so as to exert pressure on top of the magnets 6 and hold them in constant firm contact with the respective top surfaces of the magnetic strips 2. The flange surfaces ll between the respective edges of the casing B and the outer edges of the plate I provide a supporting flange surface which may be suitably held on the bottom of a channel or conduit with the casing 3 outside the conduit, or which may otherwise suitably rest upon other supporting surfaces wherein this magnetic unit may be installed.
The casing 8 may be made of a material of limited magnetic properties, namely of a poor conductor, which i capable of closing the magnetic field across the plates above the magnets and thereby increasing the magnetic effectiveness or efficiency of the unit. For instance a slightly permeable stainless steel, such as the so-called type 304 stainless steel was found suitable. This steel has about 2% manganese content. This type of steel can be case hardened. This casing acts like a keeper across the magnetic circuit. The object is to have a wide airgap for throwing the magnetic field comparatively high, yet retain as much residual magnetic induction as a narrower airgap would retain. A casing which for all practical effects and purposes is non-magnetic, but is conductive to a slight degree acts in the arrangement as herein described to retain a higher level of residual magnetic induction than the level normally retained with the given airgap.
The unit herein described may be mounted in any channel, chute or conduit through which food products or the like pass, or the unit may be mounted on moving parts. In each application magnetic particles are effectively collected upon the magnetic strips 2, but neither such particles nor any food particle or the like can be lodged anywhere except on smooth exposed surfaces of the unit, from where such particles can be easily swept off or cleaned.
A magnetic plate unit including a pair of spaced magnetic strips, a non-magnetic strip integrally joined with said magnetic strips and filling the space therebetween at a continuous level and in the plane of said magnetic strips, said strip assembly forming a single uninterrupted plate having a smooth operating surface, permanent magnet means straddling said non-magnetic strip on the plate side opposite said operating surface, opposite poles of said permanent magnet means engaging the respective adjacent magnetic strips, a housing completely covering said permanent magnet means and being integrally united with the adjacent face of said plate, said References Cited in the file of this patent UNITED STATES PATENTS Numb er Name Date 2,179,625 Groden Nov. 14, 1939 2,187,240 Karasick Jan. 16, 1940 2,348,967 Duby May 16, 1944 2,517,174 Bradley Aug. 1, 1950 OTHER REFERENCES Indiana Permanent Magnet Manual No. 4, The Indiana Steel Products Co., Chicago, 111., p. 5.