EP0143091B1 - Induktionsheizgerät für ringförmige Produkte, insbesondere Rollenlager - Google Patents

Induktionsheizgerät für ringförmige Produkte, insbesondere Rollenlager Download PDF

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Publication number
EP0143091B1
EP0143091B1 EP19840850307 EP84850307A EP0143091B1 EP 0143091 B1 EP0143091 B1 EP 0143091B1 EP 19840850307 EP19840850307 EP 19840850307 EP 84850307 A EP84850307 A EP 84850307A EP 0143091 B1 EP0143091 B1 EP 0143091B1
Authority
EP
European Patent Office
Prior art keywords
switch
ptc
current
article
induction heater
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19840850307
Other languages
English (en)
French (fr)
Other versions
EP0143091A1 (de
Inventor
Carsten Aronsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SPM Instrument AB
Original Assignee
SPM Instrument AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SPM Instrument AB filed Critical SPM Instrument AB
Publication of EP0143091A1 publication Critical patent/EP0143091A1/de
Application granted granted Critical
Publication of EP0143091B1 publication Critical patent/EP0143091B1/de
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/101—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces
    • 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
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power

Definitions

  • the invention relates to an induction heater for heating annular articles, of the type recited in the preamble of appended claim 1.
  • Such induction heaters are known to the art and described e.g. in DE-A-2 812 166. They are primarily used when wishing to heat ball bearings or some other kind of ring-shaped article, in order to mount the same on a shaft and obtain a shrink-fit on said shaft as the article cools.
  • the annular article is made of- a ferromagnetic material, the article must normally be demagnetized, which is effected by allowing the alternating current conducted through the primary coil to decrease gradually down towards zero.
  • An object of the invention is to eliminate these disadvantages. Another object is to provide a simple and inexpensive construction in respective of those circuits which are intended to be active in the reduction of current for the demagnetizing function.
  • PTC-resistors are a type of resistor whose resistance increases with temperature. They are available on the market and are normally specified by their resistance value at room temperature and the so-called switch temperature, at which temperature the resistance increases quite strongly at relatively small relative changes in temperature.
  • the operating mode of the invention is as follows.
  • the primary coil is initially connected, via the switch, which is closed, directly to the mains network (50 or 60 Hz; e.g. 220 or 110 V), wherewith the transformer induces in the annular article a current which produces heat, as a result of the inherent resistance of the article.
  • the article is heated to the extent desired, by suitably determining the duration of the heating phase.
  • the article is demagnetized, which is the phase in which the present invention becomes operative.
  • the heated article is magnetized in alternate directions during successive half-periods of the mains frequency, with progressively reduced amplitudes, causing demagnetization in the same way as when the current is decreased in the known heating methods.
  • the switch is suitably arranged to co-act with a timing device which breaks the switch after a given period of time has lapsed, this length of time being determined in accordance with the size of the article to be heated, the shape of the article and other properties thereof, and in accordance with the desired final temperature.
  • the switch consists of a pair of contacts in a relay.
  • the invention foresees, to this end, to include two or more PTC-resistors in parallel, of which only one is switched-in at a time, e.g. by means of individual switches, which may be triacs. Because these valves are not phase-angle controlled, but either switched on or off, only negligible electromagnetic interference signals are generated.
  • the circuit may incorporate, for example, a signal lamp which lights up when the heating phase is completed.
  • this heating phase can take several minutes, during which time the operator may not have the whole of his attention concentrated on the heater.
  • Figure 1 illustrates schematically a transformer construction which includes a U-shaped transformer core 1 and a magnetic yoke 3, which can be removed to allow an annular metal article to be heated, such as a ball bearing (not shown), to be fitted thereonto.
  • a primary coil 2 comprises a winding of 260 turns and is dimensioned for a current of 10-15 A.
  • the transformer itself includes about 12 kg of transformer plate (for 110 V the number of turns is half this number and the current twice as strong).
  • Mains current is passed from a master switch (not shown), through the coil 2 via a switch 4, which is a relay, whose coil current is controlled by a timing circuit T with adjustable switch-in time.
  • a mechanical clock or an electronic clock e.g. powered with mains frequency, which is preferred.
  • a PTC-resistor 5, 5' Connected in parallel with the switch 4 in a respective branch line is a PTC-resistor 5, 5', each in series with a respective switch 7 and 8 effective in triggering said resistors alternately, these switches being in the form of triacs.
  • the switch 4 When using the transformer, the switch 4 is first closed for a given length of time of from 0.5 to 10 mins. and is then broken. One of the triacs 7, 8 is conductive. When the switch is broken, the current will flow via the one PTC-resistor, which soon becomes so hot that the current therethrough becomes progressively negligible.
  • PTC-resistors of the make ITT from the company Multikomponent AB
  • each in the form of two parallel-coupled -resistors which when cold each have a resistance of 10 ohm and thus together a resistance of 5 ohm.
  • a small drop in voltage soon occurs and the resistors become hot and the resistances thereof quickly increase to several kilo-ohms.
  • the PTC-resistors had a switch temperature of 115°C.
  • the Figure 1 embodiment also includes a lamp 9, which lights-up when the heating phase is terminated.
  • FIG. 2 and 3 The detailed circuit diagram shown in Figures 2 and 3 is largely self-explanatory and incorporates conventional components. It will be observed that a voltage divider is placed over the primary coil and its output C is coupled to a circuit which via firing output terminals D and E selects either of the triacs 7 and 8 to be conductive next and to extinguish the conductive triac when the voltage across the primary coil 2 has fallen, and which further causes firing of a light diode 9 upon termination of the demagnetizing phase.
  • An electronic clock circuit is supplied at B with an alternating current of 50-periods and, at a point in time determined by the setting of a potentiometer 10, opens the switching contact of the relay 4 via a signal A. Since such circuit diagrams are fully obvious to the electronics engineer, the information given above is deemed quite sufficient to render the switching circuit readily understandable.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • General Induction Heating (AREA)
  • Control Of Resistance Heating (AREA)

Claims (3)

1. Induktionsheizgerät zum Heizen von ringförmigen Gegenständen, insbesondere von Kugellagern, mit einem U-förmigen Transformatorkern (1), der mit einer Primärwicklung (2) und einem Magnetjoch (3) versehen ist, welches in der Lage ist, einen durch den Transformatorkern verlaufenden Magnetkreis zu schließen und auf welchem ein ringförmiger Gegenstand aufgenommen wird, der als Einzelwindungs-Sekundärwicklung zum Heizen des Gegenstandes durch einen induzierten Strom arbeitet, und ferner mit einem ersten Schalter (4), der zum Koppeln der Primärwicklung mit einer Wechselstromnetzversorgung in Reihe mit der Primärwicklung (2) geschaltet ist, und mit einer Einrichtung, die zum Entmagnetisieren des Gegenstandes den Strom, der von der Wechselstromnetzversorgung durch die Primärwicklung fließt, schrittweise reduziert, dadurch gekennzeichnet, daß die Einrichtung einen PTC-Widerstand (5) aufweist, der bei Raumtemperatur einen niedrigen Widerstand von unter etwa 20 ohm hat und der bei Erwärmung nach Durchleiten eines Stroms durch den PTC-Widerstand (5) einen Widerstand hat, der mindestens 100 fach größer ist, und daß die Einrichtung ferner einen weiteren PTC-Widerstand (5') aufweist, wobei jeder der beiden PTC-Widerstände (5, 5') in Reihe mit einem jeweiligen zweiten Schalter (7, 8) geschaltet ist und jede Reihenschaltung aus einem PTC-Widerstand (5 oder 5') und einem zweiten Schalter (7 oder 8) dem ersten Schalter (4) parallelgeschaltet ist, wobei die zweiten Schalter derart angeordnet sind, daß sie alternativ eingeschaltet werden.
2. Induktionsheizgerät nach Anspruch 1, dadurch gekennzeichnet, daß der erste Schalter ein Relais (4) ist und daß ein einstellbarer Zeitgeber (6) mit der Wicklung des Relais gekoppelt ist.
3. Induktionsheizgerät nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die zweiten Schalter (7, 8) Triacs sind.
EP19840850307 1983-10-21 1984-10-18 Induktionsheizgerät für ringförmige Produkte, insbesondere Rollenlager Expired EP0143091B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8305807A SE439718B (sv) 1983-10-21 1983-10-21 Induktionsvermare for vermning av ringformade produkter, serskilt rullningslager
SE8305807 1983-10-21

Publications (2)

Publication Number Publication Date
EP0143091A1 EP0143091A1 (de) 1985-05-29
EP0143091B1 true EP0143091B1 (de) 1989-01-18

Family

ID=20353002

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840850307 Expired EP0143091B1 (de) 1983-10-21 1984-10-18 Induktionsheizgerät für ringförmige Produkte, insbesondere Rollenlager

Country Status (3)

Country Link
EP (1) EP0143091B1 (de)
DE (1) DE3476314D1 (de)
SE (1) SE439718B (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5248865A (en) * 1989-12-18 1993-09-28 Tyler George W Apparatus for induction heating of bearings or the like
AU622056B2 (en) * 1989-12-18 1992-03-26 Feeney, Charles Heating of bearings and the like
CN102171471B (zh) * 2008-09-30 2015-01-07 Skf公司 轴承加热器
CN102280237A (zh) * 2010-06-11 2011-12-14 吴昌德 一种调节电阻阻值的方法
US9810113B2 (en) 2015-03-09 2017-11-07 The Boeing Company Engine lubrication heating system
CN105118606B (zh) * 2015-09-11 2017-05-31 浙江大学 用于在线消除电磁式电流互感器剩磁的退磁电路及方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2942162A (en) * 1953-07-02 1960-06-21 Maximilian C Becker Demagnetizers and methods for demagnetizing
DE1097059B (de) * 1959-10-12 1961-01-12 Kugelfischer G Schaefer & Co Verfahren zum elektrisch-induktiven Erwaermen von Metallringen
US3845442A (en) * 1971-02-03 1974-10-29 Nichicon Capacitor Ltd Automatic degaussing device
CH621659A5 (en) * 1978-01-18 1981-02-13 Greiner Electronic Ag Method and device for inductive heating electrically conductive workpieces
AT365028B (de) * 1978-04-11 1981-12-10 Vertina Anstalt Verfahren und anlage zum induktiven erwaermen von metallischen werkstuecken

Also Published As

Publication number Publication date
SE8305807D0 (sv) 1983-10-21
DE3476314D1 (en) 1989-02-23
SE8305807L (sv) 1985-04-22
SE439718B (sv) 1985-06-24
EP0143091A1 (de) 1985-05-29

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