Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Work or object holding type
Reexamination Certificate
2000-02-15
2001-09-18
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Work or object holding type
C335S288000, C269S008000, C294S065500
Reexamination Certificate
active
06292078
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a manually controlled magnetic anchoring device by means of which ferrous parts can be clamped. In particular, in the description which follows, we will refer to an anchoring device intended to act as a magnetic hoist for loads even high in weight, without thereby forming a limitation to the field of application of the requested patent, given that such a device can be used for example also for restraining a ferrous workpiece in a predetermined position.
DESCRIPTION OF THE RELATED ART
According to the inventor the most efficient model of magnetic hoist in the relevant known state of the art is that formed by two permanent magnetic cores, whereof one core can be inverted manually through approximately 180 degrees and henceforth shall be defined as rotor core, and the other is a stator core normally divided into two or more parts and henceforth shall be defined stator core.
The aforesaid rotation will dispose the magnetic field of the rotor core alternatively in repulsion or attraction with the magnetic field generated by the stator core. In the first case the working zone of the hoist will be activated, in the second case, by disposing the two magnetic cores in reciprocal attraction, the working zone will be demagnetised.
Both in the active and passive phase said hoist uses ferromagnetic components which form both the conductor poles for activating the working zone and the external short circuiting yoke of the stator core.
The hoist device described hitherto has serious constructional problems.
It is in fact formed by various components which are to be machined separately and then assembled by means of a plurality of screws and/or welds.
Despite all the work of careful assembly such a device has the undoubted disadvantage of not tolerating excessive mechanical stresses, with the risk of misalignment of the active work surface defined by the two collector poles and a consequent functional and performance deterioration.
Another penalising aspect is apparent, during the phase of activation of the hoist, due to the high dispersion of the magnetic flux which occurs mainly through the four lateral surfaces of the magnetic poles, generally in the form of a parallelepiped. Due to the perfect isotropy of steel, which is the material forming the collector poles, the quantity of magnetic flux, contained inside the pole and suitable for crossing the collector poles and then closing on the part to be hoisted, and which disperses outwards, is higher the larger the total surface of the pole directly exposed to the air.
SUMMARY OF THE INVENTION
The object of the present invention is thus that of providing a magnetic anchoring device which avoids the disadvantages mentioned above and namely that of providing a magnetic hoist which during activation reduces to a minimum the dispersion of magnetic flux linked to the collector poles, and which at the same time is solid and robust in such a way as to improve efficiency and offer a high standard of performance.
Another object of the present invention is that of providing a magnetic anchoring device which, on a par with the magnetic material used, generates a higher magnetic power although allowing its weight and hence overall dimensions to be reduced.
A further object of the present invention is that of providing a magnetic anchoring device with a simple structure and whose parts do not require precision machining, which are long and complex or in any case such as to make it expensive.
Finally an object of the present invention is that of providing a versatile, practical, easy to handle and convenient use magnetic anchoring device.
These objects are achieved with a manual magnetic anchoring device in accordance with the claims listed below.
In the magnetic anchoring device according to the present invention a monolithic ferromagnetic block is provided which defines laterally and above the neutral crown or yoke for short circuiting of the stator core, and below the two collector poles or pole pieces. While two grooves branch off from the opposite lateral walls of the monolithic block, extending inwards to house the stator core, on the front wall of the monolithic block a substantially circular opening is formed which penetrates longitudinally inwards to house the reversible rotor core. Advantageously this monolithic block solution produces a mechanically resistant device. Thanks to the material continuity between the pole pieces and the neutral crown, there are no points of attachment, by means of screws or the like, which in the traditional embodiment do not offer complete reliability given that around them the forces arising from accidental and unexpected stresses of a dynamic nature are preferably concentrated, including above all vibrations or impact, and arising from expected stresses due to transients of activation or inhibition of the hoist and to the weight of the load to be hoisted.
The spaces for housing the stator and rotor cores are formed through milling of the monolithic block; this type of machining is fast, practical, simple, economical and convenient to the extent wherein it allows a single multi-use finished product to be obtained from an unmachined monolithic block, comprising not only, as mentioned, the grooves for housing the stator and rotor cores, but also the neutral crown and the two pole pieces. The advantages achieved in this case are even more evident if we consider that, traditionally, the neutral crown and the two pole pieces, being intended for different purposes, are machined separately and at times even require separate machining processes.
In an extremely advantageous manner the rotor core is inserted in a respective housing formed in one single piece, thus further reducing the number of parts of the device.
Since it is not possible for constructional and functional reasons to eliminate completely the losses of flux distributed along the whole magnetic circuit, it has however been possible to restrict them considerably during activation of the hoist, finding an optimal and extremely convenient arrangement of the stator and rotor cores and conferring on the magnetic collector poles a new shape which allows one of the four lateral surfaces to be eliminated which, traditionally, tend to disperse the flux.
More particularly the two magnetic collector poles are approximately defined by the portions of the monolithic ferromagnetic block enclosed between the stator and rotor cores, while the work surface is defined by the two end and coplanar surfaces of the above mentioned portions of the monolithic block.
REFERENCES:
patent: 2280437 (1942-04-01), Levesque
patent: 5166654 (1992-11-01), Doyelle
patent: 2038677 (1971-01-01), None
Cardone Michele
Giglio Antonino
Barrera Ramon M.
Tecnomagnete S.p.A
Young & Thompson
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