EP1353342B1 - Method and device for demagnetizing objects - Google Patents

Method and device for demagnetizing objects Download PDF

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Publication number
EP1353342B1
EP1353342B1 EP02405298A EP02405298A EP1353342B1 EP 1353342 B1 EP1353342 B1 EP 1353342B1 EP 02405298 A EP02405298 A EP 02405298A EP 02405298 A EP02405298 A EP 02405298A EP 1353342 B1 EP1353342 B1 EP 1353342B1
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Prior art keywords
current
coils
objects
demagnetising
inverter
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German (de)
French (fr)
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EP1353342A1 (en
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Albert Maurer
Urs Meyer
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Priority to AT02405298T priority Critical patent/ATE522915T1/en
Priority to EP02405298A priority patent/EP1353342B1/en
Priority to CNB031092365A priority patent/CN100409380C/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F13/00—Apparatus or processes for magnetising or demagnetising
    • H01F13/006—Methods and devices for demagnetising of magnetic bodies, e.g. workpieces, sheet material

Definitions

  • the invention relates to a method and an apparatus for demagnetizing objects according to the preambles of the independent claims.
  • a known method for demagnetizing objects uses an open magnetic core with a coil, which is traversed by a constant alternating current. The magnetic core is placed on the object and the alternating current is turned on. The magnetic core is then slowly pulled away from the object by hand. In an apparatus for this method, the size and weight of the magnetic core are limited. The demagnetization process is strongly influenced by environmental conditions and not precisely reproducible. Degaussing is incomplete and not always good.
  • a coil tunnel is used with large coils through which alternating current flows.
  • the article is pulled through the coil tunnel with a stationary magnetic field.
  • the object is the magnetic field first increasingly, then exposed to decreasing.
  • the demagnetizing effect is limited to a single direction.
  • the US-A-4,672,345 discloses opposed, AC-powered coils.
  • the US-A-4,384,513 shows an apparatus for demagnetizing objects with only one coil, which is part of a series resonant circuit, which is powered by an investor Stromes.
  • residual magnetism in articles is becoming an increasingly important problem.
  • the residual magnetism present in objects becomes a central quality criterion for suppliers.
  • Higher technology and material selection can reduce the cost factor, especially in mass production.
  • the object of the invention is to provide a method with which objects can be demagnetized so far that no measurable residual magnetism is more present.
  • Another object of the invention is to provide a device with which objects can be demagnetized according to the method.
  • the demagnetization process is done in two separate steps. First, magnetically hard areas, such as welds, pressure points, etc., are pretreated in the shadow mask locally locally with high fields by means of choke coils in the alternating field. These magnetically hard areas are thereby at least partially demagnetized.
  • the entire system in this case the perforated plate as a whole with the associated frame and attachments, is completely demagnetized.
  • the perforated plate is pulled through an alternating magnetic field, ver it remains locally for a certain time in the magnetic field within a station.
  • the change of the alternating field in this station is controlled by electronically controlling the coils electronically in frequency and amplitude.
  • the alternating field is brought to zero, whereupon the perforated plate the station is removed. It is now demagnetized so far that no residual magnetism is measurable. The process of demagnetization thus takes place in cycles.
  • the demagnetization device comprises a transport line 1, to which the objects to be demagnetized, transported away and further.
  • the transport route leads past at least one, but preferably a plurality of pretreatment stations 2 and then passes through the demagnetization station 3.
  • Each pre-treatment station 2 comprises a choke coil 21-24 of a type known per se.
  • the demagnetization station 3 comprises two mutually opposite boxes 31, 32 which each comprise a coil.
  • the two boxes with the spaced coils form a zone in which a homogeneous field is generated.
  • the two coils are part of a coupled synchronous Serieschwingnikes, which is current controlled by means of an inverter.
  • the two coils in the boxes 31, 32 are arranged opposite each other on both sides of a conveyor belt.
  • the objects are now transported in time on the transport route from pretreatment station 2 to pretreatment station 2 and finally through the demagnetization station 3. In each station the object remains for a certain period of time.
  • the magnetically hard areas are pretreated by strong fields, so that they can no longer be identified as such and the magnetic properties are reasonably balanced.
  • the magnetic properties of the objects are now reduced to no longer measurable values. Also in this station, the objects remain stationary during the influencing time required for this purpose.
  • the residence time of the object in the alternating field must be at least equal to a period of approximately 100 periods or alternating pulses.
  • the penetration depth of the magnetic strength at the same amplitude of the alternating field in the object of the frequency of the alternating field is dependent. This also gives the residence time.
  • a frequency of the alternating field of about 200 Hz is suitable, which corresponds to a residence time of at least 0.5 seconds. As the penetration depth or material thickness required increases, the frequency decreases.
  • the required frequency of the alternating field is about 10 Hz and thus an influence time of at least 10 seconds is required.
  • the frequency of the alternating field is now optimized by selecting the frequency as high as possible according to the properties of the object.
  • the station thus includes two such boxes, one on each side of the item.
  • the Serieschwing Vietnamese brings basically by the change of charge and short circuit decaying vibrations. Now the Serieschwing Vietnamese is controlled with a current controller or inverter. This provides a further advantage in that the temperature in the coil itself can be monitored and kept constant. Thus, the generated field remains precise without unwanted temperature influence.
  • the current controller is provided with a zero point correction. The zero point correction sets any residual current to zero after the oscillations of the alternating field have faded away. Thus, there is no voltage and no charge present at the time the object is removed from the station.
  • the oscillation in the series resonant circuit is controlled only via the current regulator and thus the oscillation circuit is controlled in a controlled manner and the vibrations are also controlled to decay.
  • a duration of at least 5 periods is typically used as the preprocessing time Vt. At the beginning even a slight override can be accepted. Only after the presence of the required current, ie after the expiry of the at least 5 periods, can the oscillating circuit be damped to oscillate during the required decay time At.
  • the control of the series oscillating circuits uses a current regulation of the inverter with rectangular pulses. Now, the desired demagnetization curve is controlled by supporting one or more of the oscillations with an additional square pulse at the beginning of the rise. Thus, the attenuation of the vibrations and thus the expiration of the demagnetization can be selected according to the problem.
  • the duration of the process is given by the above-mentioned principles. In order to determine the end of the process one must count only the impulses respectively the oscillations. For the specification of a final value deviating from zero, one can abort the process after a certain preselected number of oscillations.
  • a monitoring of the process and the final values obtained can be done by separate field measurement using separate coils or Hall sensors.
  • the zero point correction of the current controller / inverter automatically comes into operation and sets any residual current to zero after the oscillations of the alternating field have faded.
  • This is an extraordinary one Advantage for the device for demagnetization. Since the transport of the objects is timed by the conveyor belt, there is no reason for operators to intervene by hand and make any manipulations. Because there is no voltage at this time, no electricity flows and no charges in the Serieschwing Vietnameseen longer exist, there is no risk of electric shock to operating personnel. So if the device is finally turned off, no residual charges are no longer available. This makes repairs and maintenance, eg. on the conveyor, completely harmless.

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Abstract

The method involves demagnetizing objects between two mutually opposing coils forming part of a series oscillation circuit. The object is stationary between the coils for a defined period during demagnetization and the series oscillation circuit is current controlled by an inverter. The desired current is maintained for at least 5 periods and the occupation time is at least approximately 100 periods. AN Independent claim is also included for the following: an arrangement for demagnetizing objects.

Description

Die Erfindung betrifft ein Verfahren und eine Vorrichtung zum Entmagnetisieren von Gegenständen nach den Oberbegriffen der unabhängigen Ansprüche.The invention relates to a method and an apparatus for demagnetizing objects according to the preambles of the independent claims.

Ein bekanntes Verfahren zum Entmagnetisieren von Gegenständen benützt einen offenen Magnetkern mit einer Spule, welche von einem konstanten Wechselstrom durchflossen wird. Der Magnetkern wird auf den Gegenstand aufgelegt und der Wechselstrom eingeschaltet. Darauf wird der Magnetkern langsam von Hand vom Gegenstand weggezogen. Bei einer Vorrichtung für dieses Verfahren sind Grösse und Gewicht des Magnetkerns begrenzt. Der Entmagnetisiervorgang ist stark durch Umgebungsbedingungen beeinflusst und nicht präzise reproduzierbar. Die Entmagnetisierung ist unvollständig und nicht immer gleich gut.A known method for demagnetizing objects uses an open magnetic core with a coil, which is traversed by a constant alternating current. The magnetic core is placed on the object and the alternating current is turned on. The magnetic core is then slowly pulled away from the object by hand. In an apparatus for this method, the size and weight of the magnetic core are limited. The demagnetization process is strongly influenced by environmental conditions and not precisely reproducible. Degaussing is incomplete and not always good.

Bei einem weitern bekannten Verfahren wird mit einem Spulentunnel mit grossen, von Wechselstrom durchflossenen, Spulen gearbeitet. Der Gegenstand wird durch den Spulentunnel mit stationärem Magnetfeld hindurchgezogen. Dadurch ist der Gegenstand dem Magnetfeld zuerst zunehmend, dann abnehmend ausgesetzt. Die entmagnetisierende Wirkung ist auf eine einzige Richtung beschränkt.
Die US-A-4 672 345 offenbart gegenüberliegende, Wechselstrom durchflossene Spulen.
Die US-A-4 384 513 zeigt eine Vorrichtung zum Entmagnetisieren von Gegenständen mit nur einer Spule, die Teil eines Serienschwingkreises ist, der mittels eines Investers stromgestenert wird.In a further known method, a coil tunnel is used with large coils through which alternating current flows. The article is pulled through the coil tunnel with a stationary magnetic field. As a result, the object is the magnetic field first increasingly, then exposed to decreasing. The demagnetizing effect is limited to a single direction.
The US-A-4,672,345 discloses opposed, AC-powered coils.
The US-A-4,384,513 shows an apparatus for demagnetizing objects with only one coil, which is part of a series resonant circuit, which is powered by an investor Stromes.

Bei der heutigen Verwendung von Materialen für mechanische Komponenten und der breiten Verwendung von empfindlichen elektronischen Komponenten und Schaltungen wird der Restmagnetismus in Gegenständen zu einem immer wichtigeren Problem. Der in Gegenständen vorhandene Restmagnetismus wird zu einem zentralen Qualitätskriterium für Zulieferer. Durch höhere Technologie und Materialauswahl kann insbesondere bei der Massenteilefertigung der Kostenfaktor reduziert werden. Allerdings handelt man sich dafür andere Störfaktoren, wie eben Restmagnetismus, ein.With today's use of mechanical component materials and the wide use of sensitive electronic components and circuits, residual magnetism in articles is becoming an increasingly important problem. The residual magnetism present in objects becomes a central quality criterion for suppliers. Higher technology and material selection can reduce the cost factor, especially in mass production. However, one deals with other disturbing factors, such as residual magnetism.

Aufgabe der Erfindung ist es, ein Verfahren anzugeben, mit welchem Gegenstände soweit entmagnetisiert werden können, dass kein messbarer Restmagnetismus mehr vorhanden ist.The object of the invention is to provide a method with which objects can be demagnetized so far that no measurable residual magnetism is more present.

Eine weitere Aufgabe der Erfindung besteht darin, eine Vorrichtung anzugeben, mit welcher entsprechen dem Verfahren Gegenstände entmagnetisiert werden können.Another object of the invention is to provide a device with which objects can be demagnetized according to the method.

Diese Aufgabe wird durch die Erfindung gemäss dem kennzeichnenden Teil der unabhängigen Patentansprüche gelöst.This object is achieved by the invention according to the characterizing part of the independent claims.

Die Erfindung wird nachstehend im Zusammenhang mit den Zeichnungen beschrieben. Es zeigen:

Figur 1
Vorrichtung in Ansicht
Figur 2 und
Entmagnetisierungskurven
Figur 3
Stützen der Schwingungen
The invention will be described below in conjunction with the drawings. Show it:
FIG. 1
Device in view
Figure 2 and
demagnetization
FIG. 3
Supporting the vibrations

Nachfolgend wird kurz auf die Grundlagen und Grundgedanken der erfindungsgemässen Verfahrens eingegangen. Als typischer Gegenstand, welcher entmagnetisiert werden soll, wird ein Bildschirm, respektive eine Lochmaske eines Bildschirmes als Ganzes mit dem dazugehörenden Rahmen und Anbauten angenommen. Diese Lochmaske dient hierbei nur als ein markantes Beispiel für solche Gegenstände.Below, the basics and basic ideas of the inventive method will be briefly discussed. As a typical object to be demagnetized, a screen, or a shadow mask of a screen as a whole with the associated frame and attachments is assumed. This shadow mask serves only as a striking example of such objects.

Das Verfahren zur Entmagnetisierung geschieht in zwei gesonderten Schritten. Zuerst werden magnetisch harte Stellen, wie Schweissnähte, Druckstellen usw., in der Lochmaske örtlich lokal mit hohen Feldern mittels Drosselspulen im Wechselfeld vorbehandelt. Diese magnetisch harten Stellen werden dadurch mindestens teilweise entmagnetisiert.The demagnetization process is done in two separate steps. First, magnetically hard areas, such as welds, pressure points, etc., are pretreated in the shadow mask locally locally with high fields by means of choke coils in the alternating field. These magnetically hard areas are thereby at least partially demagnetized.

In einem nun erfindungsgemäss entscheidenden zweiten Schritt wird das ganze System, in diesem Falle die Lochplatte als Ganzes mit dem dazugehörenden Rahmen und Anbauten, komplett entmagnetisiert. Statt dass, gemäss Stand der Technik, die Lochplatte durch ein magnetisches Wechselfeld durchgezogen wird, ver bleibt sie während einer gewissen Zeit örtlich im Magnetfeld innerhalb einer Station. Nun wird die Aenderung des Wechselfeldes in dieser Station gesteuert, indem die Spulen elektronisch in Bezug auf Frequenz und Amplitude elektronisch gesteuert werden. Nach einer gewissen Aufenthaltszeit der Lochplatte in der Station wird das Wechselfeld auf Null gebracht, worauf die Lochplatte aus der Station entfernt wird. Sie ist nun soweit entmagnetisiert, dass kein Restmagnetismus mehr messbar ist. Der Ablauf der Entmagnetisierung findet also Taktweise statt.In a second step, which is decisive according to the invention, the entire system, in this case the perforated plate as a whole with the associated frame and attachments, is completely demagnetized. Instead of that, according to the prior art, the perforated plate is pulled through an alternating magnetic field, ver it remains locally for a certain time in the magnetic field within a station. Now, the change of the alternating field in this station is controlled by electronically controlling the coils electronically in frequency and amplitude. After a certain period of residence of the perforated plate in the station, the alternating field is brought to zero, whereupon the perforated plate the station is removed. It is now demagnetized so far that no residual magnetism is measurable. The process of demagnetization thus takes place in cycles.

Die Vorrichtung nach Figur 1 zeigt eine Ausführung, welche nach diesen Grundgedanken arbeitet. Die Entmagnetisierungsvorrichtung umfasst eine Transportstrasse 1, auf welche die zu entmagnetisierenden Gegenstände zu-, weg- und weitertransportiert werden. Die Transportstrasse führt unter mindestens einer, vorzugsweise aber mehreren Vorbehandlungsstationen 2 vorbei und anschliessend durch die Entmagnetisierungsstation 3 hindurch. Jede Vorbehandlungsstation 2 umfasst eine Drosselspule 21- 24 an und für sich bekannter Art. Die Entmagnetisierungsstation 3 umfasst zwei einander gegenüberliegende Boxen 31, 32, welche je eine Spule umfassen. Die beiden Boxen mit den voneinander beabstandeten Spulen bilden eine Zone in der eine homogenes Feld erzeugt wird. Die beiden Spulen sind Teil eines gekoppelten synchronen Serieschwingkreises, welcher mittels einem Inverter stromgesteuert ist. Die beiden Spulen in den Boxen 31, 32 sind einander gegenüberliegend beiderseits eines Transportbandes angeordnet sind.The device after FIG. 1 shows an embodiment that works on these principles. The demagnetization device comprises a transport line 1, to which the objects to be demagnetized, transported away and further. The transport route leads past at least one, but preferably a plurality of pretreatment stations 2 and then passes through the demagnetization station 3. Each pre-treatment station 2 comprises a choke coil 21-24 of a type known per se. The demagnetization station 3 comprises two mutually opposite boxes 31, 32 which each comprise a coil. The two boxes with the spaced coils form a zone in which a homogeneous field is generated. The two coils are part of a coupled synchronous Serieschwingkreises, which is current controlled by means of an inverter. The two coils in the boxes 31, 32 are arranged opposite each other on both sides of a conveyor belt.

Die Gegenstände werden nun im Takt auf der Transportstrasse von Vorbehandlungsstation 2 zu Vorbehandlungsstation 2 und schliesslich durch die Entmagnetisierungsstation 3 transportiert. In jeder Station verbleibt der Gegenstand während einer gewissen Zeitspanne. In den Vorbehandlungsstationen werden die magnetisch harten Stellen durch starke Felder vorbehandelt, so dass sie nicht mehr als solche festgestellt werden können und die magnetischen Eigenschaften einigermassen ausgeglichen sind.The objects are now transported in time on the transport route from pretreatment station 2 to pretreatment station 2 and finally through the demagnetization station 3. In each station the object remains for a certain period of time. In the pre-treatment stations, the magnetically hard areas are pretreated by strong fields, so that they can no longer be identified as such and the magnetic properties are reasonably balanced.

In der eigentlichen und massgebenden Entmagnetisierungsstation 3 werden nun der die magnetischen Eigenschaften der Gegenstände auf nicht mehr messbare Werte reduziert. Auch in dieser Station verbleiben die Gegenstände während der dazu benötigten Beeinflussungszeit ortsfest.In the actual and authoritative demagnetization station 3, the magnetic properties of the objects are now reduced to no longer measurable values. Also in this station, the objects remain stationary during the influencing time required for this purpose.

Es handelt sich also um ein getaktetes Durchlaufverfahren. Für dieses getaktete Durchlaufverfahren mit dem Transport und dem Betrieb der Vorbehandlungsstationen 2 wird eine Steuerung bekannter Art verwendet. Für die Ansteuerung der Entmagnetisierungsstation 3 allein wird eine weitere und separate spezielle Inverterregelung 4 benützt. Die Taktzeiten werden dem Problem respektive den Behandlungszeiten in der einzelnen Stationen angepasst. Dabei gibt die längste Behandlungszeit in einer der Stationen die Taktrate vor. Eine Automatisierung ist möglich.So it is a clocked cycle. For this clocked-through process with the transport and operation of the pretreatment stations 2, a control of known type is used. For the control of the demagnetization station 3 alone, a further and separate special inverter control 4 is used. The cycle times are adapted to the problem respectively the treatment times in the individual stations. The longest treatment time in one of the stations determines the clock rate. Automation is possible.

Um diese zu ermöglichen werden einige Grundsätze aufgestellt. Erstens muss die Aufenthaltszeit des Gegenstandes im Wechselfeld mindestens einer Zeitspanne von annähernd 100 Perioden oder Wechselpulsen entsprechen. Zweitens ist die Eindringtiefe der Magnetstärke bei gleicher Amplitude des Wechselfeldes in den Gegenstand von der Frequenz des Wechselfeldes abhängig. Dadurch ist auch die Aufenthaltszeit gegeben. Für Material von 1mm Stärke eignet sich eine Frequenz des Wechselfeldes von etwa 200 Hz, was einer Aufenthaltszeit von mindestens 0,5 Sekunden entspricht. Mit zunehmender benötigter Eindringtiefe respektive Materialdicke nimmt die Frequenz ab. Für einen Gegenstand mit 10mm Materialdicke entspricht die benötigte Frequenz des Wechselfeldes etwa 10 Hz und damit wird eine Beeinflussungszeit von mindestens 10 Sekunden benötigt.To make this possible, some principles are set. First, the residence time of the object in the alternating field must be at least equal to a period of approximately 100 periods or alternating pulses. Secondly, the penetration depth of the magnetic strength at the same amplitude of the alternating field in the object of the frequency of the alternating field is dependent. This also gives the residence time. For material of 1mm thickness, a frequency of the alternating field of about 200 Hz is suitable, which corresponds to a residence time of at least 0.5 seconds. As the penetration depth or material thickness required increases, the frequency decreases. For an object with a 10mm material thickness, the required frequency of the alternating field is about 10 Hz and thus an influence time of at least 10 seconds is required.

Um eine schnelle Taktrate für den Durchlauf der Entmagnetisierungen zu erhalten wird nun die Frequenz des Wechselfeldes optimiert, indem man die Frequenz den Eigenschaften des Gegenstandes entsprechend möglichst hoch wählt.In order to obtain a fast clock rate for the passage of the demagnetizations, the frequency of the alternating field is now optimized by selecting the frequency as high as possible according to the properties of the object.

Dies wird nun durch Verwenden eines Serieschwingkreises mit Spule und Kondensator erreicht. Dieser ist in einer geschlossenen Box untergebracht. Dadurch kann Spannung und Strom ausserhalb der Box klein gehalten werden, während die für das Wechselfeld nötigen hohen Spannungen im Lade - Entladezyklus nur innerhalb der Box vorhanden sind. Dies verhindert Gefahren für Bedienungspersonal weitestgehend. Die Station umfasst also zwei solche Boxen, je eine auf einer Seite des Gegenstandes.This is now achieved by using a coil-capacitor series resonant circuit. This is housed in a closed box. As a result, voltage and current outside the box can be kept small, while the high voltages required for the alternating field in the charge - discharge cycle are only present within the box. This prevents dangers for operating personnel as far as possible. The station thus includes two such boxes, one on each side of the item.

Der Serieschwingkreis bringt grundsätzlich durch den Wechsel von Laden und Kurzschluss abklingende Schwingungen. Nun wird der Serieschwingkreis mit einem Stromregler oder Inverter angesteuert. Dadurch wird ein weiterer Vorteil ermöglicht, indem die Temperatur in der Spule selbst Ueberwachung und konstant gehalten werden kann. Damit bleibt das erzeugte Feld ohne unerwünschten Temperatureinfluss präzise. Der Stromregler wird mit einer Nullpunktkorrektur versehen. Die Nullpunktkorrektur stellt einen allfälligen Reststrom nach dem Abklingen der Schwingungen des Wechselfeldes auf Null. Somit ist an diesem Zeitpunkt, an dem der Gegenstand aus der Station genommen wird, keine Spannung und keine Ladung mehr anliegend vorhanden.The Serieschwingkreis brings basically by the change of charge and short circuit decaying vibrations. Now the Serieschwingkreis is controlled with a current controller or inverter. This provides a further advantage in that the temperature in the coil itself can be monitored and kept constant. Thus, the generated field remains precise without unwanted temperature influence. The current controller is provided with a zero point correction. The zero point correction sets any residual current to zero after the oscillations of the alternating field have faded away. Thus, there is no voltage and no charge present at the time the object is removed from the station.

Die Schwingung im Serieschwingkreis wird nur über den Stromregler gesteuert und damit der Schwingkreis gesteuert angeregt und die Schwingungen auch gesteuert zum Abklingen gebracht.The oscillation in the series resonant circuit is controlled only via the current regulator and thus the oscillation circuit is controlled in a controlled manner and the vibrations are also controlled to decay.

In der Figur 2 sind Beispiele von Entmagnetisierungskurven dargestellt, wie sie nach diesem getakteten Verfahren nun möglich sind. Der Serieschwingkreis bringt durch den Wechsel von Laden und Kurzschluss durch abklingende Schwingungen eine übliche Exponentialkurve E. Für Gegenstände, welche besondere Anforderungen an die Entmagnetisierung stellen, kann nun diese Entmagnetisierungskurve in eine Lineare L oder eine Krümmungskurve K verändert werden. Man kann nun die Zeitdauer bestimmen, in welcher der Restmagnetismus im Gegenstand bis auf nicht mehr messbare Werte hinuntergebracht werden kann. Der Gegenstand bleibt während dieser Dauer ortsfest im Bereich zwischen den beiden benachbarten Schwingkreisen. Die Schwingungen der Serieschwingkreise werden stromgesteuert auf einen, durch die benötigte Eindringtiefe bedingten, Sollwert (= 100%) gebracht und anschliessend auf annähernd Null (10-3 bis 10-4) zurückgefahren. Es ist so auch möglich, den Endwert bewusst abweichend von Null auf einer bestimmten Höhe zu erhalten.In the FIG. 2 Examples of demagnetization curves are shown, as they are now possible by this clocked method. The series oscillation circuit brings a usual exponential curve E by the change of charge and short circuit due to decaying oscillations. For objects which place particular demands on the demagnetization, this demagnetization curve can now be changed into a linear L or a curvature curve K. One can now determine the period of time in which the residual magnetism in the object can be brought down to no longer measurable values. The object remains stationary during this period in the area between the two adjacent oscillating circuits. The oscillations of the Serieschwingkreise are controlled by current, brought to a, due to the required penetration depth, setpoint (= 100%) and then returned to approximately zero (10 -3 to 10 -4 ). It is thus also possible to consciously receive the final value deviating from zero at a certain height.

Um den Sollwert des Stromes zu erhalten wird typischerweise eine Dauer von mindestens 5 Perioden als Vorlaufzeit Vt eingesetzt. Dabei kann zu Beginn sogar eine leichte Uebersteuerung in Kauf genommen werden. Erst nach Vorhandensein der benötigten Stromstärke, also nach Ablauf der mindestens 5 Perioden, lässt man den Schwingkreis dämpfend ausschwingen während der benötigten Ausschwingzeit At. Die Steuerung der Serieschwingkreise wird eine Stromregelung des Inverters mit Rechteckimpulsen verwendet. Nun wird die gewünschte Entmagnetisierungskurve gesteuert, indem man zu Beginn des Anstieges einzelner oder jeder der Schwingungen mit einem zusätzlichen Rechteckimpuls stützt. Damit kann die Dämpfung der Schwingungen und damit der Ablauf der Entmagnetisierung dem Problem entsprechend gewählt werden. Die Dauer des Vorganges ist durch oben erwähnte Grundsätze gegeben. Um das Ende des Vorganges festzustellen muss man nur die Impulse respektive die Schwingungen zählen. Für die Vorgabe eines Endwertes abweichend von Null kann man den Vorgang nach einer bestimmten vorgewählten Anzahl Schwingungen abbrechen.In order to obtain the setpoint value of the current, a duration of at least 5 periods is typically used as the preprocessing time Vt. At the beginning even a slight override can be accepted. Only after the presence of the required current, ie after the expiry of the at least 5 periods, can the oscillating circuit be damped to oscillate during the required decay time At. The control of the series oscillating circuits uses a current regulation of the inverter with rectangular pulses. Now, the desired demagnetization curve is controlled by supporting one or more of the oscillations with an additional square pulse at the beginning of the rise. Thus, the attenuation of the vibrations and thus the expiration of the demagnetization can be selected according to the problem. The duration of the process is given by the above-mentioned principles. In order to determine the end of the process one must count only the impulses respectively the oscillations. For the specification of a final value deviating from zero, one can abort the process after a certain preselected number of oscillations.

Eine Ueberwachung des Vorganges und der erhaltenen Endwerte kann durch separate Feldmessung mittels getrennten Spulen oder Hall-Senoren erfolgen.A monitoring of the process and the final values obtained can be done by separate field measurement using separate coils or Hall sensors.

Nach dem gesteuerten Ausschwingen der Serieschwingkreise tritt automatisch die Nullpunktkorrektur des Stromreglers/Inverters in Funktion und stellt jeden allfälligen Reststrom nach dem Abklingen der Schwingungen des Wechselfeldes auf Null. Somit ist zu diesem Zeitpunkt, während dem der Gegenstand aus der Station genommen wird, keine Spannung und keine Ladung mehr anliegend vorhanden. Dies ist ein ausserordentlicher Vorteil für die Vorrichtung zum Entmagnetisieren. Da der Transport der Gegenstände durch das Transportband getaktet erfolgt, besteht kein Anlass für Bedienungspersonen, von Hand einzugreifen und irgendwelche Manipulationen vorzunehmen. Weil zu diesem Zeitpunkt keine Spannung mehr anliegt, kein Strom mehr fliesst und keine Ladungen in den Serieschwingkreisen mehr vorhanden sind, besteht auch keine Gefahr von elektrischen Schlägen für Bedienungspersonal. Wenn also die Vorrichtung schliesslich abgestellt ist, sind auch keinerlei Restladungen mehr vorhanden. Dies macht Reparaturen und Wartung, bsp. am Transportband, völlig ungefährlich.After the controlled oscillation of the series oscillating circuits, the zero point correction of the current controller / inverter automatically comes into operation and sets any residual current to zero after the oscillations of the alternating field have faded. Thus, at this time, while the article is being removed from the station, there is no tension and no more charge. This is an extraordinary one Advantage for the device for demagnetization. Since the transport of the objects is timed by the conveyor belt, there is no reason for operators to intervene by hand and make any manipulations. Because there is no voltage at this time, no electricity flows and no charges in the Serieschwingkreisen longer exist, there is no risk of electric shock to operating personnel. So if the device is finally turned off, no residual charges are no longer available. This makes repairs and maintenance, eg. on the conveyor, completely harmless.

Claims (10)

  1. A method for demagnetising objects between two mutually opposite coils, characterised in that the coils are part of a series oscillating circuit and in that the object is fixed in the region between the two coils during the retention time of a certain duration and in that the series oscillating circuits are current-controlled by means of an inverter.
  2. The method according to Claim 1, characterised in that the setpoint current is maintained for a duration of a minimum of 5 periods.
  3. The method according to Claim 1, characterised in that the retention time lasts approximately 100 periods.
  4. The method according to any one of Claims 1 to 3, characterised in that the periods of the series oscillating circuits are reduced by means of an inverter in a current-controlled manner from a setpoint current to a final current along a demagnetisation curve in a controlled manner.
  5. The method according to Claim 4, characterised in that the demagnetisation curve is achieved by supporting individual oscillations of the series oscillating circuits by supporting the amplitude by means of rectangular pulses by the inverter.
  6. The method according to Claim 4, characterised in that final current can be preselected and in that following the completion of the demagnetising procedure, the series oscillating circuits are made voltageless, currentless and chargeless by means of a zero-point correction.
  7. A device for demagnetising objects, with a demagnetising station (3) which comprises a coil, characterised in that two mutually spaced coils are present, which form a homogeneous field zone in-between and which are part of a series oscillating circuit which is current-controlled by means of an inverter, wherein the two coils are each arranged in a box (31, 32) opposite one another on both sides of a conveyor belt.
  8. The device according to Claim 7, characterised in that at least one pre-treatment station (2) for demagnetising magnetically hard points in the object is present in the transport direction of the conveyor belt.
  9. The device according to Claim 7, characterised in that the transport of the objects on the conveyor belt takes place in a clocked manner in start/stop operation.
  10. Use of a device according to Claim 7 for carrying out the method according to any one of Claims 1 to 6.
EP02405298A 2002-04-12 2002-04-12 Method and device for demagnetizing objects Expired - Lifetime EP1353342B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AT02405298T ATE522915T1 (en) 2002-04-12 2002-04-12 METHOD AND DEVICE FOR DEMAGNETIZING OBJECTS
EP02405298A EP1353342B1 (en) 2002-04-12 2002-04-12 Method and device for demagnetizing objects
CNB031092365A CN100409380C (en) 2002-04-12 2003-04-04 Method and device for demagnetizing body

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP02405298A EP1353342B1 (en) 2002-04-12 2002-04-12 Method and device for demagnetizing objects

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EP1353342A1 EP1353342A1 (en) 2003-10-15
EP1353342B1 true EP1353342B1 (en) 2011-08-31

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Publication number Priority date Publication date Assignee Title
AT394730B (en) * 1990-05-08 1992-06-10 Voest Alpine Ind Anlagen METHOD FOR PRODUCING EXO- AND ENDOCELLULASE-FREE XYLANASE
CH698521B1 (en) 2007-02-21 2009-08-31 Albert Maurer Demagnetizing.
DE102017109149A1 (en) 2017-04-28 2018-10-31 Marek Rohner Device and method for demagnetizing objects
DE102018108037A1 (en) 2018-04-05 2019-10-10 Marek Rohner Device and method for demagnetizing objects
CN111243825B (en) * 2018-11-29 2023-06-16 阿尔贝特·莫伊雷尔 Device for demagnetizing ferromagnetic material

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3005927A1 (en) * 1980-02-16 1981-09-03 Erich Dr.-Ing. 5300 Bonn Steingroever DEMAGNETIZING PROCEDURE
DE3500011C2 (en) * 1985-01-02 1986-04-17 Axel R. Dr.-Ing. 5900 Siegen Hidde Process for the controlled demagnetization of rod-shaped, ferromagnetic and tempered semi-finished or finished products in the ongoing production process
US4672345A (en) * 1985-09-24 1987-06-09 Electro-Matic Products Co. Degausser/demagnetizer
DE9003286U1 (en) * 1990-03-21 1990-05-23 Agfa-Gevaert Ag, 5090 Leverkusen Demagnetization device for magnetic recording media
CN2073151U (en) * 1990-10-04 1991-03-13 中国康复研究中心康复工程研究所 Information eraser of magnetic recording carrier
CN2081559U (en) * 1991-02-08 1991-07-24 中国科学院物理研究所 High-capacity magnetizing and demagnetization machine
CN2164095Y (en) * 1993-04-09 1994-05-04 太原西迪计算机公司 Pulse eraser
GB9411594D0 (en) * 1994-06-09 1994-08-03 Welding Inst Demagnetisation of materials

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ATE522915T1 (en) 2011-09-15
EP1353342A1 (en) 2003-10-15
CN100409380C (en) 2008-08-06
CN1452188A (en) 2003-10-29

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