US3174884A - Method of surface hardening steel rolls and apparatus for carrying out the same - Google Patents

Method of surface hardening steel rolls and apparatus for carrying out the same Download PDF

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Publication number
US3174884A
US3174884A US177039A US17703962A US3174884A US 3174884 A US3174884 A US 3174884A US 177039 A US177039 A US 177039A US 17703962 A US17703962 A US 17703962A US 3174884 A US3174884 A US 3174884A
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United States
Prior art keywords
roll
temperature
heating
hardening
hardened
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Expired - Lifetime
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US177039A
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English (en)
Inventor
Seulen Gerhard
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Deutsche Edelstahlwerke AG
AEG AG
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Deutsche Edelstahlwerke AG
AEG AG
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/38—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for roll bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
    • C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/40—Direct resistance heating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • a well known technique for raising the temperature of the surfaces which are to be hardened and one which is used particularly for the surface-hardening of rolls is that of inductive or conductive heating.
  • inductive hardening did away with the necessity of raising the temperature of the entire roll to hardening temperature and of then quenching the same for forming the desired hard surface skin. It permitted the surface of the roll to be heated to a given depth and to be quenched without affecting the core of the roll. Consequently a tough core could be formed with a hard skin. In the course of extended practical experience this method has been developed to give very satisfactory results.
  • the technique of progressive hardening is employed. This consists in advancing an inductor across the roll surface and in quenching the surface by spraying it immediately behind the inductor.
  • various techniques such as a slow speed of advance or the provision of two inductors in tandem as well as the choice of low frequencies for energising the inductor coil, it was impossible to obtain satisfactory hardened layers of greater depth.
  • this is the aim there is considerable risk of the outermost skin being damaged and of hair cracks appearing after a time. It was therefore necessary to compromise by foregoing the advantage of greater depth of the hardened zone in favour of obtaining an unexceptionable surface skin.
  • the object envisaged by the invention is a method which permits forged or cast steel rolls to be more penetratively hardened than was heretofore possible, without injury to the outermost layer, and without affecting the core of the roll by the heat treatment.
  • this problem is solved by heating the roll to above a critical temperature with the application of a high electric power intensity whilst at the same time cooling the surface to temperatures lower than the critical temperature. be to immediately above or below the Ac point.
  • the object of cooling in these cases was to keep the surface areas which were not to be hardened cold enough to prevent these cooled areas from hardening.
  • the surface of the workpiece is adjacently cooled to prevent its temperature from rising to beyond the critical Ac point.
  • inductive heating cooling is performed in the region which is actually under the influence of the inductors.
  • conductive heating the entire surface of the workpiece through which the current passes must be cooled.
  • the use of a high power density nevertheless permits a temperature peak above the Ac temperature to be generated inside the workpiece at a not in- ;considerable distance from the surface without much difficulty. This means that a temperature peak is generated inside the work without overheating the external surface and without injuring the outermost skin of the workpiece.
  • the hardening effect can be arranged to penetrate far deeper into the work than was hitherto possible. Moreover an external surface which has not sustained damage can thus be created because at no time is the outside surface overheated.
  • the greater penetrative effect of this hardening process has the further result that the hardened zones are better supported and are unlikely to yield when later they are exposed to considerable loads.
  • the invention therefore eliminates a deficiency of surface-hardened workpieces which are later exposed to high loads.
  • Conductive heating has the special advantage of being highly efficient with a high power factor.
  • the desired temperature equalisation between the temperature peak inside the workpiece and the cooled external layer can take place if there is an interval of delay between the termination of cooling and the beginning of quenching.
  • the process can be assisted by supplementary inductive heating. This is especially useful if the workpieces consist of extremely temperature-sensitive steels. In such steels the temperature peak must not significantly exceed the actual hardening temperature.
  • supplementary heating is useful. Supplementary heating can ensure that the temperature distribution curve between the external skin and the point where the temperature peak had been created is completely horizontal, whereas temperature equalisation without additional heating results in a temperature curve which slightly rises towards the points where the temperature peak had been established.
  • the proposed method is ideal for deep hardening without affecting the structure of even deeper zones and of the core.
  • the temperature at which the external skin should be maintained by cooling will generally depend upon the workpiece dimensions, the electrical power applied, the duration of heating and other factors. Conveniently, cooling will be so arranged that the permeability of the cooled zone remains low. Temperatures between 600 and 780 C. should be best.
  • the invention proposes to provide an inductor with a cooling sprayer arranged to act directly upon the zones on the workpiece which are under the influence of the nductor. At an adjustable distance behind this combined inductor and sprayer is a quenching sprayer. In a particularly simple arrangement the coolant may be sprayed on to the workpiece through the coil of the inductor itself.
  • FIG. 1 An arrangement of this kind is schematically illustrated in FIG. 1.
  • the roll 1 is being surface-hardened according to the method proposed by the invention.
  • an inductor coil 3 comprising several turns surrounds the roll.
  • the coolant which keeps the outer skin cold despite the application of a high electrical power density is sprayed between the turns of the coil of the inductor 3 on to the surface 1 of the roll which is exposed to the induction effect of the coil. This is indicated by arrows 4;
  • the roll moves through the inductor as indicated by arrow 5.
  • FIG. 2 illustrates an alternative in which the work 1 is taken through the coil in translato-ry motion in direction of arrow besides being simultaneously rotated about its axis as indicated by arrow 3. It is therefore possible in a manner known as such to provide one or more loops of the heating conductor, in the illustrated example those marked 9, with magnetically permeable laminations 10. Coolant spraying nozzles 11 are located 4 between these loops 9. It will be understood that when axially advancing and simultaneously rotating the roll the same effect can be achieved as that described by reference to FIG. 1.
  • the quenching sprayer is indicated at 7,
  • the equalisation of temperatures can be assisted by the provision of a further inductor in the intervening zone.
  • the entire cylindrical part 1 of roll 2 is embraced by the coils of an inductor 12.
  • the coolant is sprayed on to the surface through the gaps between adjacent turns in the direction indicated by arrow 13.
  • power is cut off and the temperatures are allowed to equalise during a waiting perod at the end of which the roll is quenched.
  • power can be supplied to the coil during this period of Waiting whilst the cooling spray is shut off. It may be advisable to rotate the roll to ensure that the coolant and quenching medium will have a uniformly even effect.
  • the coolant and quenching medium may be sprayed consecutively between the turns of the coil.
  • the sprayer may surround the inductor.
  • FIG. 4 shows an arrangement in which a heating loop 14 is arranged to extend axially along the length of the cylindrical part 1 of the roll.
  • This loop is provided in conventional manner with magnetically permeable sheet metal laminations 15.
  • the roll 2 rotates whilst advancing, and it will be readily understood that the entire surface of the roll will thus be heated.
  • a sprayer 16 Immediately behind the inductor is a sprayer 16 through which a coolant and a quenching medium can be supplied in succession.
  • the quenching sprayer may take the form of a box 17 which surrounds the entire induction device.
  • a power intensity of say 0.1 kw./sq. cm. surface will be needed.
  • the temperature of the outer skin is maintained at 750 0., whereas the temperature peak in the interior may be 890 C.
  • a temperature of 850 C. may be established substantially throughout the zone from the former peak to the external surface.
  • the temperature peak is generated at a depth of 15 mm. by using a frequency of 500 c./s. A depth of the hardened zone of 20 mm. can thus be established with ease.
  • the invention further proposes to apply the current supply contacts in the form of rollers or slippers to the ends' of the roll and to locate them in a common axial plane through a roll generator.
  • a linear zone of the roll surface can thus be raised to elevated temperature. Since the roll also rotates about its own axis the heating effect will affect the entire cylindrical surface, rotation of the roll being continued until an even surface temperature distribution at the desired level has been achieved.
  • FIG. 5 illustrates two different forms of such an arrangement.
  • Roll 1 revolves as indicated by arrow 2.
  • Contactrollers 3 or possibly slippers supply current to the end of the cylindrical part of the roll. This disposition is employed if it is desired to create a hardened zone as indicated by the dotted line at 4, i.e., a zone which ends slightly short of the ends 5 of the cylindrical part of the roll.
  • the production of hardened zones of this kind is known, their object being to prevent the hard brittle edges at 5 from breaking away and chipping.
  • the rollers or slippers would be located at 7 on the end faces of the roll above the neck near the edges of the cylindrical portion.
  • the slippers or contact rollers are conveniently watercooled to remove the heat generated by contact resistance and the heat generated in the contact bodies themselves and in their supply leads.
  • a method of surface-hardening rolls of forged or cast steel that can be hardened by heating and quenching which comprises heating the roll around its periphery by the application of a high electrical power density and thereby generating a temperature peak above the Ac point in the work under the surface while at the same time within the same axial extent of the roll in which heating is thus taking place cooling the surface to temperatures in the region of the A0 point and then discontinuing the cooling and allowing the temperature between the said peak and the surface to equalise and the temperature of the whole of the zone which is to be hardened to rise to a temperature at least up to the AC3 point and then quenching the said zone.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
US177039A 1961-03-04 1962-03-02 Method of surface hardening steel rolls and apparatus for carrying out the same Expired - Lifetime US3174884A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DED35561A DE1205999B (de) 1961-03-04 1961-03-04 Verfahren und Vorrichtung zum Oberflaechen-haerten von geschmiedeten oder gegossenenWalzen aus Stahl

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3505133A (en) * 1969-04-09 1970-04-07 Bethlehem Steel Corp Roll heat treating method
US20110084062A1 (en) * 2009-09-10 2011-04-14 Sms Elotherm Gmbh Device for inductive heating and use of such a device
EP3108018A1 (de) * 2014-02-21 2016-12-28 ThyssenKrupp Rothe Erde GmbH System, fertigungsanlage und verfahren

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3008374A1 (de) * 1980-03-05 1981-09-17 Aeg-Elotherm Gmbh, 5630 Remscheid Verfahren zur haertung der oberflaeche von rohrwalzen und vorrichtung zur induktiven erwaermung von rohrwalzenkoerpern

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US400366A (en) * 1889-03-26 Process of hardening steel
US2479934A (en) * 1943-08-26 1949-08-23 Gen Motors Corp Heat treating
US2600290A (en) * 1950-08-08 1952-06-10 Du Pont Process for quench-hardening steel
US2799606A (en) * 1954-02-23 1957-07-16 Michael W Freeman Products for and methods of quenching to harden steels
US2819056A (en) * 1955-06-13 1958-01-07 Induction Heating Inc Apparatus for heat-treating steel
US2857154A (en) * 1950-11-30 1958-10-21 Delapena & Son Ltd Apparatus for heat treating toothed articles by high frequency induction heating
US2930724A (en) * 1958-01-27 1960-03-29 Magnetic Heating Corp Process for induction heating and quenching of metal

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE767227C (de) * 1939-09-30 1952-03-03 Deutsche Edelstahlwerke Ag Verfahren und Vorrichtung zum Oberflaechenhaerten von metallischen Gegenstaenden mittels induktiver Erhitzung
GB749609A (en) * 1952-07-18 1956-05-30 Deutsche Edelstahlwerke Ag Method of inductively hardening the surfaces of rolls

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US400366A (en) * 1889-03-26 Process of hardening steel
US2479934A (en) * 1943-08-26 1949-08-23 Gen Motors Corp Heat treating
US2600290A (en) * 1950-08-08 1952-06-10 Du Pont Process for quench-hardening steel
US2857154A (en) * 1950-11-30 1958-10-21 Delapena & Son Ltd Apparatus for heat treating toothed articles by high frequency induction heating
US2799606A (en) * 1954-02-23 1957-07-16 Michael W Freeman Products for and methods of quenching to harden steels
US2819056A (en) * 1955-06-13 1958-01-07 Induction Heating Inc Apparatus for heat-treating steel
US2930724A (en) * 1958-01-27 1960-03-29 Magnetic Heating Corp Process for induction heating and quenching of metal

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3505133A (en) * 1969-04-09 1970-04-07 Bethlehem Steel Corp Roll heat treating method
US20110084062A1 (en) * 2009-09-10 2011-04-14 Sms Elotherm Gmbh Device for inductive heating and use of such a device
EP3108018A1 (de) * 2014-02-21 2016-12-28 ThyssenKrupp Rothe Erde GmbH System, fertigungsanlage und verfahren

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Publication number Publication date
DE1205999B (de) 1965-12-02

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