EP2963660A1 - Unregulated alternating current demagnetiser - Google Patents

Abstract

In an uncontrolled Wechselstromomentmagnetisierer (1), comprising an AC circuit (10) and an AC voltage source (100), wherein the AC circuit (10) by means of actuation of a switch (S), the AC loading of a parallel resonant circuit (P), comprising a Entmagnetisierspule (L) and a to the demagnetizing coil (L) in parallel parallel capacitor (C1) allowed, the possibility should be created to minimize the susceptibility to error during demagnetization of users who have no knowledge of the processes during demagnetization. This is achieved by the fact that the alternating current in the inductance L oscillates freely when the semiconductor element D is switched off. To limit the inrush current due to the parallel capacitor C1, at least one electronic component (D) is arranged in series with the AC voltage source (100) and can be operated by means of a switch (S). The AC circuit (10) is switched on exactly at the zero crossing of the AC voltage source (100). Conveniently, a series capacitor (C2) is connected in series with the demagnetizing coil (L) in the AC circuit (10).

Description

Technical area

The present invention describes an uncontrolled Wechselstrommagnetmagnetierer, comprising an AC circuit and an AC voltage source, wherein the AC circuit by means of actuation of a switch, the AC loading of a parallel resonant circuit, comprising a demagnetization and a demagnetizer parallel-connected parallel capacitor allows.

State of the art

For degaussing ferromagnetic components or components with ferromagnetic components, uncontrolled Wechselstromentmagnetisierer be used for some time.

By means of an alternating voltage, which usually alternates with the mains frequency, an alternating current flow is generated by at least one inductance and thereby an alternating magnetic field in the vicinity of the inductance. In order to generate sufficiently high alternating magnetic fields, the uncontrolled AC magneto must be designed such that a current flow of several amps through the at least one inductor safely can flow. The uncontrolled Wechselstrommagnetmagnetierer usually available in the form of Plattenentmagnetisierern or handheld demagnetizers are manually operated and handy, with a simple electronic circuit is used. The alternating alternating voltage can be easily switched on and off by means of a switch, wherein after switching on, the alternating voltage is applied uncontrolled to the at least one inductor and the corresponding alternating magnetic field is induced until it is switched off. During operation, the alternating magnetic field has a defined amplitude and a constant frequency, defined by the applied alternating voltage.

The at least one inductance in the form of a correspondingly designed coil is usually magnetically coupled to C / E cores of ferromagnetic material. To enhance the magnetic field effect, the coils can be covered with plates, which also protects the coil. The plates can each still be provided with a special coating, so that the components can slide over the plates almost smoothly.

In the most technically simple case of the embodiment of a plate demagnetizer or a hand demagnetizer, a parallel resonant circuit comprising a parallel capacitor and a demagnetizing coil is used. After excitation of the parallel resonant circuit and switching off the supply of alternating voltage oscillates this, the Current amplitude automatically oscillates to zero and thus a magnetic alternating field with decreasing amplitude can be easily generated without control. Like in the US2240749 described the parallel resonant circuit is applied after turning on a switch with an AC voltage, whereby the demagnetization process can be started.

While the electrical design of both uncontrolled demagnetizers is identical, the use is different. In both cases, however, a relative movement of the component to be demagnetized is generated for the demagnetizer.

After switching on the Plattenentmagnetisierers a demagnetizing component is moved over the plate surface of the Plattenentmagnetisierers manually or for example by a transport device, wherein the component is moved into and out of the field lines again. For best demagnetization this should be done by approaching the Plattenentmagnetisierer, sweeping the plate as perpendicular to the pole transition of the C- or E-core Entmagnetisierpule and as far as possible removal of the component from the plate and thus from the field of magnetic field lines. When the demagnetizing process is carried out, optimum demagnetizing results can be obtained. In reality, however, the process looks different as part of a production process. Due to too short a discharge distance of the components of the Plate demagnetizer away, remain partly residual magnetic fields in the component stand. It is also common practice to turn off the plate demagnetizer even though the component has not yet been removed from the field of magnetic field lines. Since this maltreatment can not be considered for the component and often there are no magnetic field measuring devices for checking the demagnetization, these errors remain undetected.

If a hand demagnetizer is used, then in the optimal case, after being switched on, it is guided to a component to be demagnetized, then moved as uniformly as possible over the surface of the component at a minimum distance, and the hand demagnetizer is then removed continuously from the component. Due to the high alternating magnetic field, a continuous movement with a constant distance to the component is often not easy. The hand demagnetizer partially sticks firmly to the surface of the component and can only be moved jerkily. For simplicity, the hand demagnetizer is simply turned off to move it away from the surface. Again, unwanted residual magnetic fields remain in the component.

The component appears to be demagnetized because demagnetization has been performed from power on to turn off. The resulting disturbing residual magnetic field is usually higher than before the demagnetization process. In production, the demagnetization process must be fast be performed and the competent persons often have no idea of the processes in the demagnetization, resulting in components with strong residual magnetism.

In order to provide a secure demagnetization of ferromagnetic components, the prior art has gone from uncontrolled AC magnetic solenoids to more sophisticated electronically controlled automated demagnetizers. These are much more expensive and more complicated, but offer the user after placing the demagnetizing component the possibility of passing a controlled demagnetization curve. In this case, the alternating magnetic field is controlled down controlled, with a residual magnetism within the component is achievable, which is less than the strength of the earth's magnetic field. The controlled demagnetizers in the premium segment are extremely easy to use, which virtually eliminates errors during demagnetization.

However, for some applications and for many users, the acquisition of such controlled automated demagnetizers is too expensive and the initial cost is spared at the expense of quality.
This circuit can also be used for demagnetization coils, for example tunnel demagnetizers, which have no coupling due to an additional ferromagnetic laminated core. The parts to be demagnetized themselves produce the magnetic coupling. The Parts are de-magnetized through or over the opening of the coil.

Presentation of the invention

The present invention has for its object to provide simple and inexpensive uncontrolled Wechselstromentmagnetisierer with which the error rate of demagnetization also by users who have no idea of the processes during demagnetization to minimize.

The inventive solution can be integrated with little additional effort in conventional hand, plate or Tunnelentmagnetisierer. The considerably more complex and expensive version with external power modules or control units for pulse / ramp control is thus eliminated.

By means of the uncontrolled AC magneto magnetizer according to the invention, a good process reliability is achieved, whereby faulty manipulation is minimized.

Brief description of the drawings

Figur 1

zeigt eine schematische Ansicht einer elektronischen Schaltung eines erfindungsgemässen ungesteuerten Wechselstromentmagnetisierers.

Figur 2

zeigt den zeitlichen Verlauf der alternierenden Magnetfeldamplitude bei Betrieb des ungesteuerten Wechselstromentmagnetisierers in einer schematischen Ansicht während des Einschaltens, dem Netzbetrieb und der Ausschaltphase, wobei der Netzbetrieb stark verkürzt dargestellt ist.

A preferred embodiment of the subject invention will be described below in conjunction with the accompanying drawings.

FIG. 1

shows a schematic view of an electronic circuit of an inventive uncontrolled Wechselstromentmagnetisierers.

FIG. 2

shows the timing of the alternating magnetic field amplitude in operation of the uncontrolled Wechselstrommagnetmagnetier in a schematic view during power-up, the network operation and the off phase, the network operation is shown greatly shortened.

An uncontrolled alternating current magnetizer 1 is described, which can also be used by laypersons to carry out an optimized, less fault-prone demagnetization method.

The alternating current magnetizer 1 has an AC circuit 10, which may be mounted in a housing 11. The AC circuit 10 includes a parallel resonant circuit P having a demagnetizing coil L as an inductance and a parallel capacitor C1 as a capacitance. Both components are connected in parallel. The demagnetizing coil L consists of a plurality of turns, which are advantageously wound as closely as possible so that high magnetic field strengths can be achieved and, depending on the embodiment, can have a cylindrical or rectangular design. The parallel capacitor C1 is usually chosen as the standard motor capacitor. Typical capacitances of the parallel capacitor C1 are between 4μF and 40μF.

The parallel resonant circuit P is fed by an AC voltage source 100 which is likewise arranged parallel to the demagnetizing coil L and to the parallel capacitor C1, wherein an AC voltage having a constant frequency f and an AC voltage amplitude UAC can be acted upon by means of the AC voltage source 100. During operation, the alternating voltage induces a current flow and a resulting alternating magnetic field in the demagnetizing coil L.

Since no active control is required for uncontrolled alternating current magnetizers 1 and the demagnetization process carried out therewith, no high demands are placed on the alternating voltage source 100. The frequency f can be the mains frequency of 50 Hz or 60 Hz in the simplest case, while the alternating amplitude should be constant.
The AC circuit 10 is made switchable by a switch S, wherein when the switch S is applied, the AC voltage at the parallel resonant circuit.

For demagnetization of the AC circuit 10 is acted upon by turning on the switch S with the AC voltage. An alternating magnetic field builds up in the region of the demagnetizing coil L. Demagnetizing components 13 are subsequently guided along a plate side 12 on the demagnetizer or the demagnetizer on the components 13 to be demagnetized. The demagnetizing components 13 dive into the alternating magnetic field and then move away from the alternating magnetic field, resulting in demagnetized components 14 with almost no residual magnetic field.

The invention is based on the idea by circuitry measures to minimize incorrect manipulation during demagnetization and thereby increase process reliability.

By arranging special circuit components or measures, it is prevented that current pulses or discontinuities of the resulting alternating current lead to unwanted magnetization of the components to be demagnetized 13 when switching on and off.

As in FIG. 1 can be seen, a semiconductor device D is integrated into the AC circuit 10, which is connected in series with the AC voltage source 100 and by means of the switch S is actuated. Preferably, the semiconductor device D is a triac, with which the alternating current in the AC circuit 10 controlled while avoiding a switch-on current pulse can be turned on. Accordingly, the semiconductor device D is a current-limiting semiconductor device D, which switches the AC voltage in the zero crossing, whereby a high inrush current, which would arise due to the parallel capacitor C1, is avoided in the AC circuit 10. Thus, an early failure of the semiconductor element D or an alternative usable, conventional mechanical switch, prevented due to the high inrush currents.

In order to prevent unwanted magnetization of demagnetizing components 13 when turning off the uncontrolled demagnetizer 1, a series capacitor C2 is connected in series with the demagnetizing coil L and thus arranged within the parallel resonant circuit P. Of the Series capacitor C2 prevents a current breakdown, which can occur during operation of the uncontrolled demagnetizer 1 by manipulating the inductance of the demagnetizing coil L by approaching the demagnetizing ferromagnetic components 13. Preferably, the series capacitor C2 is a standard motor capacitor. Particularly preferably, parallel capacitor C1 and series capacitor C2 are configured identically.

Based on an on and off spectrum 2, the time course of a demagnetization is based on FIG. 2 explained. In order to start a demagnetization process, the uncontrolled demagnetizer 1 is switched on by means of switch S at a time t0. Because of the semiconductor device D, the AC circuit 10 is only at zero crossing of the AC voltage UAC time-delayed at time t1 applied to the AC voltage UAC, whereby the inrush current due to the capacitor C1 is effectively limited and the switch-on phase I passes into a mains-powered phase II ,

In this phase-driven phase II, the alternating voltage UAC with a frequency f and defined amplitude leads to an alternating current in the alternating current circuit 10 and an alternating magnetic field induced in the demagnetizing coil L with a magnetic field amplitude A with frequency f. The component to be demagnetized 13 is preferably only during the mains-powered phase II, which usually takes a few seconds, in the region of the demagnetizing coil L past the uncontrolled demagnetizer 1.

After passing the component to be demagnetized 13 and demagnetization, the switch S is switched at a time t3, whereby a switch-off phase III is started. The AC voltage UAC is separated from the AC circuit 10 and there is a decay of the parallel resonant circuit P with the resonant frequency f0 of the parallel resonant circuit P to a magnetic field amplitude A of zero at a time t4. As in FIG. 2 indicated, the resonant frequency f0 of the resonant circuit is greater than the excitation frequency f of the AC voltage UAC.

Even if a component 13 to be demagnetized would still be in the region of the demagnetizing coil L during the switch-off phase III, no undesired magnetization would take place, since an automatic decoupling takes place. The parallel resonant circuit consists of C1, C2 and L in this phase.

The AC voltage source 100 preferably supplies a constant peak-to-peak AC voltage amplitude UAC and the frequency f of the AC voltage is freely adjustable to a constant value in a frequency range of approximately 1 Hz to 100 Hz, so that the AC voltage source 100 for the desired demagnetization results at excitation frequencies f of 1 Hz to 100 Hz can be used. In practice, that will usual power grid used as AC power source 100, the AC voltages with 50Hz and 230V or 60Hz and 115V supplies.

Instead of a triac, the semiconductor device D may be formed of a plurality of thyristors, which are connected accordingly. Preferably, two thyristors are connected in anti-parallel to each other.

Experiments have shown that the capacitances of the capacitors C1 and C2 and the inductance of the demagnetizing coil L should be chosen such that the resonant frequency f0 of the parallel resonant circuit P is approximately a factor of 2 to 4 times greater than the mains frequency of 50 Hz or 60 Hz should.

LIST OF REFERENCE NUMBERS

1

uncontrolled alternating current magnetizer
10 AC circuit
100 alternating voltage source
U _{AC AC} voltage
f excitation frequency (mains frequency 50 / 60Hz)
fo resonant frequency
S switch
C ₂ series capacitor
C ₁ parallel capacitor
L demagnetizing coil (inductance)
D inrush current limiting semiconductor device
P parallel resonant circuit
11 housing
12 plate side
13 to be demagnetized component
14 demagnetized component

2

On and off spectrum

A

magnetic field amplitude

t

Time

I

Switch

II

Powered phase

III

switch-off

Claims (6)

An uncontrolled AC magneto-generator (1) comprising an AC circuit (10) and an AC source (100),
wherein the AC circuit (10) by means of actuation of a switch (S), the AC loading of a parallel resonant circuit (P) comprising a demagnetizing coil (L) and a parallel capacitor (C1) connected in parallel to the demagnetizing coil (L),
characterized in that
the AC circuit (10)
at least one electronic component (D) arranged in series with the AC voltage source (100) by means of switch (S) operable, with which the AC circuit (10) exactly defined at zero crossing of the AC voltage can be acted upon by AC voltage, whereby an inrush current pulse is avoidable,
and
a series capacitor (C2) connected in series with the Entmagnetisierspule (L) in the AC circuit (10) connected. Uncontrolled alternating current magnetizer (1) according to claim 1, characterized in that the at least one electronic component (D) is a current-limiting semiconductor component in the form of a triac (D). Uncontrolled Wechselstromentmagnetisierer (1) according to claim 1, characterized in that as at least one electronic component (D) a circuit with a plurality of thyristors, preferably a circuit with two antiparallel connected to each other thyristors is selected as Einschaltstrombegrenzendes semiconductor device. Uncontrolled alternating current magnetizer (1) according to one of the preceding claims, characterized in that the capacitances of the parallel capacitor (C1) and of the series capacitor (C2), and the inductance of the demagnetizing coil (L) are selected such that a resonant frequency (f0) of the parallel resonant circuit ( P) is about a factor of 2 to 4 times above the excitation frequency (f) of the AC voltage (UAC). Uncontrolled alternating current magnetizer (1) according to one of the preceding claims, characterized in that the series capacitor (C2) is a motor capacitor. Uncontrolled alternating current magnetizer (1) according to one of the preceding claims, characterized in that the parallel capacitor (C1) and the series capacitor (C2) are designed identically.

Images