US3161225A - Method for obtaining flat and stress-free magnetic strip - Google Patents

Method for obtaining flat and stress-free magnetic strip Download PDF

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Publication number
US3161225A
US3161225A US163283A US16328361A US3161225A US 3161225 A US3161225 A US 3161225A US 163283 A US163283 A US 163283A US 16328361 A US16328361 A US 16328361A US 3161225 A US3161225 A US 3161225A
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United States
Prior art keywords
strip
furnace
flattening
stress
coil
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 - Lifetime
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US163283A
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English (en)
Inventor
Chester E Ward
Victor W Carpenter
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Armco Inc
Original Assignee
Armco Inc
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
Priority to BE625879D priority Critical patent/BE625879A/xx
Application filed by Armco Inc filed Critical Armco Inc
Priority to US163283A priority patent/US3161225A/en
Priority to GB47727/62A priority patent/GB951749A/en
Priority to SE13722/62A priority patent/SE317694B/xx
Priority to DEA41986A priority patent/DE1275561B/de
Application granted granted Critical
Publication of US3161225A publication Critical patent/US3161225A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C47/00—Winding-up, coiling or winding-off metal wire, metal band or other flexible metal material characterised by features relevant to metal processing only
    • B21C47/34—Feeding or guiding devices not specially adapted to a particular type of apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D1/00—Straightening, restoring form or removing local distortions of sheet metal or specific articles made therefrom; Stretching sheet metal combined with rolling
    • B21D1/02—Straightening, restoring form or removing local distortions of sheet metal or specific articles made therefrom; Stretching sheet metal combined with rolling by rollers
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1238—Flattening; Dressing; Flexing
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • 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
    • C21D1/26—Methods of annealing
    • C21D1/30—Stress-relieving
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest

Definitions

  • the coils to be processed exhibit a lack of the flatness required in laminations for transformers and other applications of magnetic material.
  • various methods have hitherto been proposed to flatten the strip, such as hot roller leveling and the use of catenary units, these methods rely heavily upon tension and the resultant elongation to flatten the material and are designed primarily to remove such irregularities as longitudinal troughs, buckles, and the like commonly encountered in rolled and heat treated metallic strip.
  • Such methods are effective in flattening strip but the operation often is so severe that all of the deleterious effects of mechanical stresses are not removed and the material is then unsatisfactory for magnetic applications.
  • the second important problem encountered in the production of magnetic strip material is stress.
  • the stresses involved are mechanical stresses, such as those occasioned by the physical processing of the strip, and thermal stress resulting from fast and non-uniform cooling of the strip after the heating step in the processing.
  • These two types of stresses can be complementary and under extreme circumstances result in permanent impairment of magnetic properties, i.e., original properties are not recoverable with heat treatment for stress-relief.
  • Even if not per manently damaging, residual stresses from processing may be unduly difiicult to remove with stress-relief annealing and will, if not completely removed, cause decreased etticiency in the magnetic application. Consequently, it is highly desirable that prior processing stresses, inclusive of those introduced by flattening of the strip, be kept to an absolute minimum.
  • a principal object of the instant invention is the provision of procedures by means of which both coil set and the stresses introduced during processing of the magnetic strip material may be effectively eliminated, thereby providing strip having extreme flatness without any appreciable loss in magnetic properties.
  • a further object of the instant invention is the provision of a simple and inexpensive procedure by means of which coil set or longitudinal curvature can be effectively removed from magnetic strip material without inducing mechanical stresses which cannot be relieved in the same operation.
  • Still a further object of the invention is the provision of a technique for obtaining extreme flatness in magnetic strip material while at the same time relieving both mechanical and thermal stresses introduced in the strip during prior processing or as an incident to the removal of coil set, such techniques embodying the passage of the strip material through a heat treating furnace wherein a controlled reverse curvature is introduced into the strip to offset coil set, such reverse curvature being introduced while the strip is being subjected to a stress relieving heat treatment and advanced through the furnace with a minimum of stress-producing tension and flexing of the strip.
  • FIGURE 1 is a schematic representation of one form of apparatus suitable for carrying out the procedures of the instant invention.
  • FIGURE 2 is a schematic diagram similar to FIGURE 1 illustrating an alternative form of apparatus.
  • FIGURE 3 is a schematic diagram of another form of apparatus.
  • FIGURE 4 is a schematic diagram of still another form of apparatus having a two part pass line.
  • FIGURE 5 is a schematic diagram of yet another form of apparatus.
  • a thermal-flattening furnace is indicated at 1, such furnace being of conventional length which, while variable, may be on the order of feet.
  • the leading end of the furnace i.e., approximately the first 60 feet, is for heating and soaking; whereas the remainder of the furnace is for cooling.
  • the strip 2 is conducted through the furnace on a series of spaced apart hearth rolls 3 which are preferably driven, the strip being fed into the furnace from a pay oil reel 4 and removed by means of rewind reel 5.
  • the magnetic strip material will often be coated with a thin layer of a composition capable of reacting with the surface material of the strip while at an elevated temperature to produce an adherent solid insulating film of high resistivity on the surfaces of the strip material.
  • a coating composition such as an aqueous phosphoric acid solution
  • the tensile stress exerted on the strip should be insufiicient in combination with thermal stress to case creep or plastic elongation of the strip. Stresses of a magnitude to cause creep or plastic trated in FIGURE 1, the reverse bending of the strip can be induced -by elevating a single roll 6 above the pass line of the hearth rolls 3. Preferably, the roll 6-which can.
  • a flattening roll also will be driven and may comprise a 4 inch 'diarneter'cylindrical roll.
  • FIGURE 2 of the drawings there is illustrated a modification of the invention wherein the single reverse bending of the strip is induced by means of a series of adjacent flattening rolls 7, '8 and 9 displaced upwardly from the pass line of the strip, as: defined by the hearth rolls 3.
  • the purpose of this arrangement is to introduce a single bend in the strip in
  • the flattening roll' was positioned approximately feet from the exit end of the heating and soaking zone of the furnace.
  • the reverse bending which takes place is unidirectional, that is, the strip is deflected from the pass line in a single direction only, and while the strip returns to the pass line 'upon passage over the flattening roll, it is not bent in more than one direction nor more than one time.
  • the: flattening roll will'be movably mounted so that it may be automatically. moved 7 relative to the pass line of the 'strip'in accordance with" the diameter; of the coil being unwound That is, as
  • the cluster of flattening rolls 7, 8 and 9 define a single large diameter bending surface which enables the user to more closely calibrate the corrective deformation of the strip.
  • the coils 4 and 5 may be placed beneath the furnace and the strip lead over a series" of hearth rolls 10 arranged to define an inverted U-shaped' path of travel. With this arrangement, there .is no flexing of the strip in the direction of coil set as itpasses through the furnace. Alternatively, the coils may be placed to the sides or above the furnace and the U-shaped rolls oriented accordingly.
  • the'str'ip is taken over a series of hearth rolls 11 .to an elevated flattening roll 12, but in this'instance the pass line of the strip beyond the elevated flattening roll is raised .to the level of the flattening roll 12, the strip 7 being conveyed from the furnace on raised hearth rolls 13.
  • FIG URE 5 A further form of the invention is illustrated in FIG URE 5 wherein the hearth roll 14 lies in the pass line of gle reverse bendingof the strip without elevating or dcto compensate for the progressivelyiincreasing coil set.
  • the 'strip will pass over or under the isolated roll 14 depending upon whether the strip is payed off and reeled in from the bottom or top of the coil, respectively. It may be noted that while 'asinglefree 'catenary within the hot zone of :a furnace has been used for manytyears, it has not "been'pre'viously known to position a hearth roll in'such a mannerjthat one or two shorter catenaries-,may be formed and' con trolledto efiectfthe desired reverse bending of the-strip.
  • the instant invention contemplates proceduresbyfmeans of which extreme flatness ,eanb'e produced in magnetic strip material, such asv grain tensile stress jshould be wellsbelow r1000, lbs;.fp'er square aori ented silicon steel, by bending the "strip in one direction only-in opposition to coil setwhile at stress relieving temperature and in the absence of excessive tensile stresses.
  • the flatness characteristics of the strip are greatly enhanced while at the same time the type of magnetic damage which results from mechanically induced stresses is essentially eliminated. It will be understood that deformations of the strip, such as wavy edges, sag buckles, and the like, will be minimized by processing controls ahead of the thermal flattening treatment. Thermal stresses, such as those induced by fast and nonuniform cooling of the strip, will be controlled in the cooling section of the furnace. If desired, a cooling hood may be provided in order to provide more gradual cooling of the strip.
  • the instant procedures are particularly applicable to the treatment of coated strip since the strip is deformed only in one direction and is contacted only on one side. Consequently, the scratching, cracking, and flaking of the insulating'films during the processing and handling of the strip is minimized, thereby providing on the magnetic strip materials more uniform insulating films having high dielectric properties.
  • a process for flattening magnetic metallic strip material wherein the strip, as an incident of its processing, has been coiled and box annealed, said process comprising unwinding .the coil strip and passing it through a heat treating furnace and subjecting it to a stress relieving heat treatment and, as said strip passes through said furnace, introducing a single reverse bend in said strip in opposition to the coil set thereof by contacting one side only of the strip and deflecting it in the direction opposite to the coil set, said strip being advanced through the furnace at a tension insufiicient to produce creep or plastic elongation of the said strip which would impair its magnetic properties.
  • the pass line of said strip is defined by a series of spaced apart hearth rolls transversely disposed with respect to the path of travel of the strip and upon which the strip is supported and advanced through the furnace, and wherein the single reverse bend in said strip is effected by means of at least one flattening roll positioned to penetrate the pass line of said strip.
  • a process for the thermal flattening of grain oriented silicon steel to remove coil set and at the same time minimize mechanical stresses introduced therein by such processing comprising the steps of unwinding the coil strip and passing it through a heat treating furnace and, while said strip is passing through said furnace, subjecting it to a single reverse bend in opposition to the coil set of said strip by contacting one side only of the strip and deflecting it in the direction opposite to the coil set, said strip being advanced through said furnace at a tension insufficient to produce creep or plastic elongation of the strip which would impair its magnetic properties.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Tunnel Furnaces (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)
US163283A 1961-12-29 1961-12-29 Method for obtaining flat and stress-free magnetic strip Expired - Lifetime US3161225A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE625879D BE625879A (lt) 1961-12-29
US163283A US3161225A (en) 1961-12-29 1961-12-29 Method for obtaining flat and stress-free magnetic strip
GB47727/62A GB951749A (en) 1961-12-29 1962-12-18 Method for obtaining flat and stress-free magnetic strip
SE13722/62A SE317694B (lt) 1961-12-29 1962-12-19
DEA41986A DE1275561B (de) 1961-12-29 1962-12-27 Verfahren zur Verringerung von Spannungszustaenden beim Abrollen eines gehaspelten und in dieser Form gegluehten ferromagnetischen Metallbandes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US163283A US3161225A (en) 1961-12-29 1961-12-29 Method for obtaining flat and stress-free magnetic strip

Publications (1)

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US3161225A true US3161225A (en) 1964-12-15

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US163283A Expired - Lifetime US3161225A (en) 1961-12-29 1961-12-29 Method for obtaining flat and stress-free magnetic strip

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US (1) US3161225A (lt)
BE (1) BE625879A (lt)
DE (1) DE1275561B (lt)
GB (1) GB951749A (lt)
SE (1) SE317694B (lt)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328988A (en) * 1964-02-18 1967-07-04 Indugas Ges Fur Ind Gasverwert Method of and an apparatus for the heat treating of metal pipe
US3421925A (en) * 1965-07-30 1969-01-14 Westinghouse Electric Corp Method for producing improved metallic strip material
US4016740A (en) * 1973-12-27 1977-04-12 Nippon Steel Corporation Method and an apparatus for the manufacture of a steel sheet
US4057989A (en) * 1975-08-13 1977-11-15 Nippon Steel Corporation Method for levelling a metal strip or sheet
US5096510A (en) * 1989-12-11 1992-03-17 Armco Inc. Thermal flattening semi-processed electrical steel
WO2011157192A1 (zh) * 2010-06-13 2011-12-22 浙江伯耐钢带有限公司 一种装有余热利用装置的钢带热处理系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0591589A1 (en) * 1992-10-07 1994-04-13 Sumitomo Metal Industries, Ltd. Metal plate levelling method and apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2868702A (en) * 1952-11-04 1959-01-13 Helen E Brennan Method of forming a dielectric oxide film on a metal strip
US2922460A (en) * 1953-09-30 1960-01-26 E S C O S A Process and apparatus for straightening and feeding wire
US2980561A (en) * 1958-08-01 1961-04-18 Westinghouse Electric Corp Method of producing improved magnetic steel strip

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE674278C (de) * 1933-12-30 1939-04-13 Bethlehem Steel Corp Verfahren zur Verminderung der Neigung zu Biegungsfehlern und Verwerfungen bei Blechen oder Baendern aus Stahl
DE879250C (de) * 1945-08-07 1953-06-11 Cie Generale Du Duralumin & Du Ofen und Anlage zum fortlaufenden Ausgluehen von Metallbaendern

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2868702A (en) * 1952-11-04 1959-01-13 Helen E Brennan Method of forming a dielectric oxide film on a metal strip
US2922460A (en) * 1953-09-30 1960-01-26 E S C O S A Process and apparatus for straightening and feeding wire
US2980561A (en) * 1958-08-01 1961-04-18 Westinghouse Electric Corp Method of producing improved magnetic steel strip

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328988A (en) * 1964-02-18 1967-07-04 Indugas Ges Fur Ind Gasverwert Method of and an apparatus for the heat treating of metal pipe
US3421925A (en) * 1965-07-30 1969-01-14 Westinghouse Electric Corp Method for producing improved metallic strip material
US4016740A (en) * 1973-12-27 1977-04-12 Nippon Steel Corporation Method and an apparatus for the manufacture of a steel sheet
US4057989A (en) * 1975-08-13 1977-11-15 Nippon Steel Corporation Method for levelling a metal strip or sheet
US5096510A (en) * 1989-12-11 1992-03-17 Armco Inc. Thermal flattening semi-processed electrical steel
WO2011157192A1 (zh) * 2010-06-13 2011-12-22 浙江伯耐钢带有限公司 一种装有余热利用装置的钢带热处理系统

Also Published As

Publication number Publication date
BE625879A (lt)
GB951749A (en) 1964-03-11
DE1275561B (de) 1968-08-22
SE317694B (lt) 1969-11-24

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