Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Work or object holding type
Reexamination Certificate
2000-09-01
2001-12-18
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Work or object holding type
C335S295000, C269S008000, C294S065500
Reexamination Certificate
active
06331810
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic lifting apparatus and more particularly to an improved magnetic lifting apparatus by using neodymium magnet, which prevents the neodymium magnet from being oxidized to improve magnetic performance and endurance with switchable function of an on/off handle.
2. Description of the Related Art
The magnetic lifting apparatus is used in the art for lifting, conveying and releasing the ferromagnetic objects by magnetizing on or off switching.
Generally, the magnetic lifting apparatus comprises poleplates, interval members' therebetween, side walls and a top cover on which a hook is disposed. The plate-shaped poleplates are provided with a permanent magnet arrangement sandwiched in between. Each pair of poleplates is separated by a non-magnetic medium. A rotor is disposed to switch magnetic polarity by using the switching handle.
In the center of the rotor, there is an axial aperture through which the axle is rotatably inserted to the rotor and the polarity plates. One end of the axle is connected to the switching handle for rotation of the axle.
Depending on on/off position of the switch handle, the objects are lifted or released. In the lifted state of the objects, there is provided a locking member for preventing the rotor from unintentionally moving to the off direction.
In rotating the switch handle, the polarity of the line of magnetic force is changed as the directional position of permanent magnetic is switched. The magnetic force becomes OFF in case that the line of magnetic force is applied to the opposite poleplates divided by the non-magnetic medium. If the rotor is switched again, the direction of the line of magnetic force is applied to the poleplates, thereby adsorbing the objects under the poleplates with a strong magnetic attraction to lift and move to the desired place.
For a permanent magnetic of the magnetic lifting apparatus, the ferrite magnetic is widely used, having the remaining magnetic density under 2,000 gauss.
In order to improve, however, a relatively large size of the ferrite magnetic is required to improve magnetic attractive performance.
The large size of the ferrite magnetic necessitates a relatively large size of the magnetic lifting body in a magnetic lifting apparatus, which is disadvantageous to use and in view of the high manufacturing costs as well.
Use of the neodymium magnet in the range of the remaining magnetic density of 10,000-13,000 gauss may improve function of the magnetic body. However, the neodymium magnet has a fatal disadvantage of easy oxidation when the neodymium magnet is exposed in atmosphere, thereby lowering magnetization.
In order to prevent the above disadvantage, coating on the surface of the neodymium magnet with resin or metal may be suggested. However, use of the coated neodymium magnet in the rotor results in exfoliation of the coated film because it is inevitable to rotate in contact with the poleplates.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved magnetic lifting apparatus by using the neodymium permanent magnetic with high coercive force on the rotor in which an oxidation prevention means is formed in the vicinity of the neodymium magnet.
The other object of the present invention is to provide a magnetic lifting apparatus in which direction of the rotor is readily switched on and off with a minimum of force, thereby improving productivity and reliability.
In order to achieve the objects of the present invention, there is provided a magnetic lifting apparatus comprising: plate-shaped polarity plates
10
disposed with a predetermined interval, having non-magnetic medium thereon; an interval member
20
for keeping the interval between the polarity plates
10
; top cover
30
covering the interval member
20
and the polarity plates
10
, having a hook
31
on the upper side; neodymium magnet
40
having S/N polarity in opposite and disposed between the polarity plates
10
; a rotor
50
rotated with the neodymium magnet
40
being inserted therein; a switch handle
60
for switching the polarity position of the rotor
50
and the neodymium magnet
40
engaged therewith to make magnetic attraction on and off; and an oxidation prevention means
70
for blocking the neodymium magnet
40
from oxygen. The magnetic lifting apparatus of the invention has a characteristic to prevent the neodymium magnet from oxidation, to have superior endurance and performance.
In the present invention, the switch handle is readily manipulated to switch on and off magnetic attraction performance, thereby improving productivity and reliability.
The scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, the given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 5266914 (1993-11-01), Dickson et al.
patent: 5382935 (1995-01-01), Doyelle
patent: 5435613 (1995-07-01), Jung
Barrera Ramon M.
Reed Smith Hazel & Thomas LLP
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