Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Patent
1983-01-13
1985-01-29
Eisenzopf, Reinhard J.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
361156, H01H 4730
Patent
active
044970110
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a switching unit for changing the absolute value and the direction of the permanent magnetization of ferromagnetic bodies, for example of permanent magnets, this unit possessing a circuit for generating current-pulses which comprises an energy-storage system, a firing circuit and a controllable electronic switch, this electronic switch being designed in the form of a gas-discharge tube, and possessing a firing electrode, this switching unit also possessing at least one coil which is suitable for receiving the ferromagnetic body and is connected to the circuit for generating current-pulses, and further relates to a permanent-magnet clamping device for clamping workpieces which can be attracted magnetically, this clamping device possessing a plurality of permanent magnets which are, with respect to their poles, arranged side-by-side and separated by walls.
In order to polarize a permanent magnet, or to alter its polarity, in particular to reverse its polarity, a magnetic body must be briefly subjected to a strong magnetic field, directed in the direction counter to the existing polarity. A strong, short-lived magnetic field of this nature can be generated in a coil, for example an air-core coil, when a high current, in the form of a pulse, flows through this coil. For generating the pulse-current, an arrangement is known from German Auslegeschrift No. 1,054,581, this arrangement possessing capacitors as energy-storage devices and a series-connected circuit assembly comprising a discharge tube and the coil, this circuit assembly being connected in parallel to these capacitors. A discharge tube of this type, known, for example, as a thyratron, or as an ignitron, functions as a controllable gas-filled electrical valve, that is to say as an electronic switch for discharging the energy-storage devices, and is an elaborately constructed current-gate comprising a thermionic cathode, a coolant-coil, a control grid and control anodes, as well as further valve-elements, such as, for example, specially shaped surfaces. This pulse-generation circuit for changing or reversing the polarity of a ferromagnetic body is complicated in terms of its design, is bulky and, in consequence, is relatively expensive. As mentioned, special measures must be taken for cooling a thyratron or ignitron, for example a cooling system employing water.
Attempts have, moreover, been made to generate the high pulse-currents by means of a thyristor circuit, instead of a thyratron. This results in a unit which is likewise very bulky overall, and which is incapable of the sudden generation of the high currents which are necessary. On the contrary, when thyristors are used, it is necessary, for a single polarity-reversal, to switch them at least three to four times more frequently and moreover, as a rule, to switch them ten times more frequently. This frequent switching correspondingly shortens the service lives of thyristor units of this type.
The object of the invention is to provide a switching unit for temporarily changing the magnetic field strength of a ferromagnetic body, this switching unit to be as compact as possible in terms of its construction, to be capable of implementation by means of a simple electrical circuit, and in which unit the energy-storage devices can be repeatedly discharged at high power, while the unit has, at the same time, a long service life.
This object is achieved, in a switching unit of the type initially mentioned, in that the gas-discharge tube is a flashlamp, of a short type, which is designed for high gas pressures. The flashlamp is an electronic component which is constructed in accordance with a simple design, with small volumetric measurements, so that it can be integrated into the switching unit in a space-saving manner. The lamp can switch the power required for reversing the polarity of a ferromagnetic body, without cooling of any kind, and can be manufactured at a cost which is low in comparison to a thyratron. The number of switching operations which can be achieved with the flas
REFERENCES:
patent: 2247745 (1941-07-01), Brader
patent: 2287543 (1942-06-01), Vang
patent: 2786970 (1957-03-01), Connoy
patent: 3959688 (1976-05-01), Bonazoli
patent: 4354218 (1982-10-01), Steingroever et al.
patent: 4399482 (1983-08-01), Inoue
Eisenzopf Reinhard J.
Levy Edward F.
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