Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Work or object holding type
Patent
1986-10-07
1987-09-01
Harris, George
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Work or object holding type
335294, H01F 720
Patent
active
046911839
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
This invention relates to the machine-tool engineering, and, more specifically, to devices for magnetically holding workpieces to be machined on machine-tools.
STATE OF THE ART
Known in the prior art are devices for magnetically holding workpieces, comprising a magnetic field source in the form of coils enclosing steel cores and, disposed thereon, a plate intended to support workpieces (cf. U.S. Pat. No. 2,435,737.
The plate of the above cited device has recesses intended to separate unlike poles. These recesses are filled with a non-magnetic material, e.g. aluminium, and they do not fully perforate the plate to protect the magnetic field source against fouling with cutting fluids used in machining.
With this constructional arrangement of the plate, between the bottom of the recesses and the plate surface facing the magnetic field source, local zones are formed in the plate through which magnetic flux tends to leak, whereby the efficiency of the device is lowered.
DISCLOSURE OF THE INVENTION
The invention is based on the problem of providing such a device for magnetically holding workpieces in which a plate is designed in such a manner as to guarantee a comparatively high efficiency, while preserving sealing of the device.
The above problem is solved by that in a device for magnetically holding workpieces to be machined on machinetools, comprising a magnetic field source, and, disposed thereon, a plate whose surface supporting workpieces has recesses intended to separate magnetic poles, according to the invention, the plate, on its surface facing the magnetic field source, has auxiliary grooves shifted with respect to the recesses in such a manner that the distance from the bottom of the recess to the plate surface facing the magnetic field source, the distance between the recess and the auxiliary groove, and the overlap between the recess and the auxiliary groove are substantially equal to one another.
The device for magnetically holding workpieces to be machined on machine-tools according to this invention, while being comparatively simple in its design, makes it possible to considerably increase attraction forces generated by the device and improve its uniformity, hence consequently, to improve its reliability and safety in operation.
BRIEF DESCRIPTION OF THE DRAWINGS
In what follows, there is a description of a specific embodiment of this invention, with reference to the accompanying drawings, wherein:
FIG. 1 shows a device for magnetically holding workpieces according to the invention (a cross-sectional view); and
FIG. 2 graphically shows the relationship of the attraction force generated by the device V. geometric parameters of its plate.
PREFERRED EMBODIMENT OF THE INVENTION
Now, referring to FIG. 1, a device for magnetically holding workpieces 1 comprises a base 2 supporting cores 3 with coils 4 forming a source of magnetic field. A plate 5 is mounted over the magnetic field source for supporting the workpieces 1, the place being made of a ferromagnetic material.
The plate 5, on its side adapted to support the workpieces 1, has recesses 6 intended to define magnetic poles in the plate 5. The recesses 6 are filled with a non-magnetic material, such as a non-ferrous metal alloy.
The plate 5, on its side facing the magnetic field source 3, 4, has auxiliary grooves 7 symmetrically disposed above the coils 4, in between, and with an overlap with the recesses 6.
The auxiliary grooves 7 are shifted with respect to the recesses 6 at a distance "a" which is equal to the distance "b" from the bottom of the recess 6 to the plate 5 side facing the magnetic field source 3, 4, and which is also equal to the amount "c" of overlap between the recess 6 and the auxiliary groove recess 7.
Alternatively, the auxiliary grooves 7a may be disposed over the cores 3 as shown in FIG. 1.
The plate 5 may be circular in shape, in which case the recesses 6, auxiliary grooves 7, 7a, cores 3, and coils 4 are made annular in shape and disposed concentrically.
The device for magnetically holding workpi
REFERENCES:
patent: 1180457 (1916-04-01), Walker
patent: 2275839 (1942-03-01), Boehne
patent: 2435737 (1948-02-01), Carson
O. Ya. Konstantinov "Magnitnaya Tekhnologicheskaya Osnastka", 1974, Mashitroenie, (Leningrad), cf. pp. 159, 160, 218, 221, 222.
O. Ya. Konstantinov "Raschet i Konstruirovanie Magnitnykh i Electromagnitnykh Prisposobleny", 1967, Mashinostroenie (Leningrad), cf. pp. 52, 53.
B. M. Malkin "Magnitnye Prisposoblenia k Metallorezhuschim Stankam", 1965, Mashinostroenie (Moskva, Leningrad), cf. pp. 28, 29.
Gamarnik Iosif I.
Khinkus Alexandr S.
Rashkovich Mikhail P.
Trostanovsky Boris A.
Vernikov Arkady Y.
Harris George
Odesskoe Spetsialnoe Konstruktorskoe Bjuro Spetsialnykh Stankov
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