US3898108A - Box annealing of steel strip coils - Google Patents

Box annealing of steel strip coils Download PDF

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Publication number
US3898108A
US3898108A US371984A US37198473A US3898108A US 3898108 A US3898108 A US 3898108A US 371984 A US371984 A US 371984A US 37198473 A US37198473 A US 37198473A US 3898108 A US3898108 A US 3898108A
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United States
Prior art keywords
coil
steel strip
strip
annealing
projection
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Expired - Lifetime
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US371984A
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Masaru Iwasaki
Isoshi Tokisada
Shinichi Miyamoto
Toshimi Kawabata
Hiroshi Sato
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Nippon Steel Corp
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Nippon Steel Corp
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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
    • C21D9/52—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
    • 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
    • C21D9/663—Bell-type furnaces

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  • ABSTRACT A box annealing method for a steel strip coil which comprises placing a steel strip coil having a projection on its side edge portion on a base plate of a box annealing furnace, and annealing the coil.
  • the present invention relates to box annealing of steel strip coils for reducing strain caused in the side edge portions of the coil, particularly strain caused in the side edge portion which contacts the annealing furnace base plate.
  • cold-rolled steel sheets are coiled and annealed for releaving strain caused by cold-rolling, and in case of electrical steel sheets, the sheets are coiled and annealed after cold-rolling to the final size for adjustment of the chemical composition, such as, for decarburization and denitrization or grain adjustment.
  • the steel strip coils are piled in the furnace with their coil axis being perpendicular to the furnace base plate and annealed.
  • the coils box-annealed in this way are susceptible to strain caused in their side edge portions which contact the furnace base plate, and such strain in the side edge portions of the annealed coils cause significant problems if the sheets from such coils are used in a piled state, as in case of an electrical steel sheet.
  • the object of the present invention is to provide a box annealing method which can minimize the strain affected zone in the side edge portions of the steel strip.
  • Another object of the present invention is to provide a box annealing method which reduces strain in the side edge portions caused when a cold rolled steel sheet, particularly an electrical steel strip coil is annealed.
  • the present invention has its feature in that the steel sheet rolled in a strip form is coiled in such a manner that the side edge portions form projections and recessions and then the coil is placed on the base plate of the box annealing furnace with the projected edge portions of the coil facing to the base plate side, and the coil is annealed with a de sired heating cycle.
  • FIG. 1 is a cross-sectional view showing the box annealing of a steel strip coil
  • FIG. 2 (a) (b) and (c) are cross-sectional views of steel strip coils according to the present invention.
  • any of ordinary steel, special steel and electrical steel can be treated by the present invention, but the present invention is particularly suitable for annealing electrical steel strip coil, which is box-annealed after it has been rolled to its final size.
  • Steel strip which does not need subsequent shape correction, such as, temper rolling can be obtained.
  • shape correction including the temper rolling
  • the present invention is remarkably advantageous for preventing lowering of the commercial value of the product.
  • the steel strip to be treated by the present invention is rolled to the final size by any known means. Then the steel strip is coiled while the strip is swung left and right so that the side edge portions of the coiled strip form projections and recessions.
  • the first half of the steel strip may be coiled so as to form the projection 2 and the latter half of the strip may be coiled so as to form the recession 3 as shown in FIG.2(a).
  • the strip is coiled in such a manner that the recession 4 and the projection 5 appear alternatively with a constant cycle through the whole course of the ceiling, but the recession 4 and the projection S are formed with the same number of coilings or with different numbers of coilings.
  • the projection 2 or 5 serves as a support for the coil on the base plate 7. Then the coil is annealed with a desired heating cycle.
  • the material to be annealed namely a steel strip coil and the base plate 7 of the annealing furnace expand or contract depending on the changes in the heat treatment temperature, and generally their expansions or contractions do not completely coincide.
  • the lower side of the strip coil namely the side contacting the base plate 7 is strained due to the perpendicular load by its own weight and the horizontal load by the abrasion, and thus is very susceptible to plastic deformation at high temperatures.
  • the horizontal force imposed on the side edge portion of the coil due to the expansion or contraction caused by the change in the annealing temperature can be limited only in the projection and prevented from expanding inside the projection or to nonprojected portions.
  • EXAMPLE I A grain-oriented electrical steel strip which had been rolled to its final size was coiled in such a manner that the first half of the strip is coiled with the normal position and the latter half was coiled by displacing the strip to one side, and the thus obtained coil was placed in the furnace with the inside projections contacting the base plate 7 as shown by FIG. 2(a), and box-annealed at l C.
  • EXAMPLE 3 Grain-oriented electrical steel strip which had been cold rolled to its final size was coiled while the strip was swung left and right each 20 coilings, and the thus obtained coil was placed on the base plate 7 of the box an nealing furnace as shown by FIG. 2(c) and annealed at 50C. The results show the strain formation was remarkably reduced as shown in Table 1.
  • a method for box annealing a steel strip coil and for decreasing the strains resulting in the sheet from non-uniform annealing which comprises forming a coil of a steel strip such that at least one edge of the coil has a projection thereon which is parallel to the winding axis of the coil and is disposed about the circumference of the coil to provide a stable support for the coil when placed on the edge having the projection by swinging the steel strip left and right during coiling; placing the coil on a base plate of a box annealing furnace such that each coil rests on the projection. and annealing the

Abstract

A box annealing method for a steel strip coil which comprises placing a steel strip coil having a projection on its side edge portion on a base plate of a box annealing furnace, and annealing the coil.

Description

United States Patent Iwasaki et al.
BOX ANNEALING OF STEEL STRIP COlLS Inventors: Masaru lwasaki, Kitakyushu; lsoshi Tokisada, Nakama; Shinichi Miyamoto, Kitakyushu; Toshimi Kawabata, Kitakyushu; Hiroshi Sato, Kitakyushu, all of, Japan Assignee: Nippon Steel Corporation, Tokyo,
Japan Filed: June 21, 1973 Appl. No.: 371,984
Foreign Application Priority Data June 23, I972 Japan 47-62360 US. Cl. 148/112; l48/l2; l48/l3;
l48/l34; 148/155; 242/78.l; 432/5; 432/6 Int. Cl.. CZld 1/26; C2ld 9/68 Primary Exuminer-C. Lovell Attorney, Agent, or FirmT0ren, McGeady and Stanger [57] ABSTRACT A box annealing method for a steel strip coil which comprises placing a steel strip coil having a projection on its side edge portion on a base plate of a box annealing furnace, and annealing the coil.
1 Claim, 4 Drawing Figures BOX ANNEALING OF STEEL STRIP COILS The present invention relates to box annealing of steel strip coils for reducing strain caused in the side edge portions of the coil, particularly strain caused in the side edge portion which contacts the annealing furnace base plate.
Generally, cold-rolled steel sheets are coiled and annealed for releaving strain caused by cold-rolling, and in case of electrical steel sheets, the sheets are coiled and annealed after cold-rolling to the final size for adjustment of the chemical composition, such as, for decarburization and denitrization or grain adjustment.
When the annealing operation is conducted by box annealing, the steel strip coils are piled in the furnace with their coil axis being perpendicular to the furnace base plate and annealed.
The coils box-annealed in this way are susceptible to strain caused in their side edge portions which contact the furnace base plate, and such strain in the side edge portions of the annealed coils cause significant problems if the sheets from such coils are used in a piled state, as in case of an electrical steel sheet.
Such strains will not often cause a problem in case of ordinary cold-rolled steel sheets, since the sheets are further temper rolled after the annealing. However, in case of cold rolled steel sheets which are not subjected to treatments, such as, temper rolling after the annealing, and particularly in case of electrical steel sheets, the side edge portions affected by the above strain are cut off. In case the strain-affected portions are not cut off, it is necessary to apply shape-correction treatments.
The object of the present invention is to provide a box annealing method which can minimize the strain affected zone in the side edge portions of the steel strip.
Another object of the present invention is to provide a box annealing method which reduces strain in the side edge portions caused when a cold rolled steel sheet, particularly an electrical steel strip coil is annealed.
Other objects of the present invention will be clear from the following descriptions and the attached drawings.
For attaining the above object, the present invention has its feature in that the steel sheet rolled in a strip form is coiled in such a manner that the side edge portions form projections and recessions and then the coil is placed on the base plate of the box annealing furnace with the projected edge portions of the coil facing to the base plate side, and the coil is annealed with a de sired heating cycle.
The present invention will be described in more details by referring to the attached drawing.
FIG. 1 is a cross-sectional view showing the box annealing ofa steel strip coil, and FIG. 2 (a) (b) and (c) are cross-sectional views of steel strip coils according to the present invention.
Any of ordinary steel, special steel and electrical steel can be treated by the present invention, but the present invention is particularly suitable for annealing electrical steel strip coil, which is box-annealed after it has been rolled to its final size. Steel strip which does not need subsequent shape correction, such as, temper rolling can be obtained. In the case when the shape correction, including the temper rolling, is done at the separate places, for example, at user's shops, the present invention is remarkably advantageous for preventing lowering of the commercial value of the product.
The steel strip to be treated by the present invention is rolled to the final size by any known means. Then the steel strip is coiled while the strip is swung left and right so that the side edge portions of the coiled strip form projections and recessions.
In this case, the first half of the steel strip may be coiled so as to form the projection 2 and the latter half of the strip may be coiled so as to form the recession 3 as shown in FIG.2(a).
According to another coiling method, it is also possible to coil the first half of the strip so as to form the simple projection 2 and coil the latter half of the strip so as to form the recession 3 having a concave 4 and a convex 5 alternatively by swinging the strip left and right while it is coiled. (See FIG. 2(b)) According to a still another coiling method, the strip is coiled in such a manner that the recession 4 and the projection 5 appear alternatively with a constant cycle through the whole course of the ceiling, but the recession 4 and the projection S are formed with the same number of coilings or with different numbers of coilings.
When the steel strip coil coiled by swinging the strip left and right so as to have projections and recessions on its side edge portions is placed on the base plate 7 of the annealing furnace with the said side edge portion faced to the base plate, the projection 2 or 5 serves as a support for the coil on the base plate 7. Then the coil is annealed with a desired heating cycle.
During the course of annealing, the material to be annealed, namely a steel strip coil and the base plate 7 of the annealing furnace expand or contract depending on the changes in the heat treatment temperature, and generally their expansions or contractions do not completely coincide. Thus, the lower side of the strip coil, namely the side contacting the base plate 7 is strained due to the perpendicular load by its own weight and the horizontal load by the abrasion, and thus is very susceptible to plastic deformation at high temperatures.
When the coil is supported on the base plate by means of the projection 2 or 5 formed on the side edge portion contacting the base plate according to the present invention, the horizontal force imposed on the side edge portion of the coil due to the expansion or contraction caused by the change in the annealing temperature can be limited only in the projection and prevented from expanding inside the projection or to nonprojected portions.
As above mentioned, it is possible to prevent expansion of the strain affected portion of the strip coil by forming a projection on the side edge portions of the coil to be box-annealed according to the present invention.
The present invention will be more clearly understood from the following embodiments.
EXAMPLE I A grain-oriented electrical steel strip which had been rolled to its final size was coiled in such a manner that the first half of the strip is coiled with the normal position and the latter half was coiled by displacing the strip to one side, and the thus obtained coil was placed in the furnace with the inside projections contacting the base plate 7 as shown by FIG. 2(a), and box-annealed at l C.
As seen from the results shown in Table l the strain formation was remarkably reduced by the present invention as compared with the conventional method.
EXAMPLE 2 Low-carbon cold rolled steel strip which had been cold rolled to its final size was coiled in such a manner that the first half of the coil was coiled by displacing the strip to one side and the latter half of the strip was coiled at the normal position while the strip was swung left and right each ten coilingsv The thus obtained coil was placed on the base plate 7 with the inside projections contacting the base plate as shown by HG. 2(1)), and was box-annealed. The results are shown in Table l and the strain-affected portion was remarkably reduced.
EXAMPLE 3 Grain-oriented electrical steel strip which had been cold rolled to its final size was coiled while the strip was swung left and right each 20 coilings, and the thus obtained coil was placed on the base plate 7 of the box an nealing furnace as shown by FIG. 2(c) and annealed at 50C. The results show the strain formation was remarkably reduced as shown in Table 1.
Table l Strain-affected Zone (Depth in strip width direction) 4 Outer Middle lnner Portion Portion Portion Conventional Method 35 mm 26 mm 22 mm Present Example l 24 mm 22 mm l8 mm invention Example 2 5 mm l3 mm H] mm Example 3 10 mm [3 mm 7 mm It should be understood that the above examples do not limit the present invention, and various modifications and changes thereof may be made within the scope of the present invention. For example, the projection and the recession on the side edge portion of the coil may be formed by coiling a steel strip having appropriate notches on one side of the strip.
What is claimed is:
l. A method for box annealing a steel strip coil and for decreasing the strains resulting in the sheet from non-uniform annealing which comprises forming a coil of a steel strip such that at least one edge of the coil has a projection thereon which is parallel to the winding axis of the coil and is disposed about the circumference of the coil to provide a stable support for the coil when placed on the edge having the projection by swinging the steel strip left and right during coiling; placing the coil on a base plate of a box annealing furnace such that each coil rests on the projection. and annealing the

Claims (1)

1. A METHOD FOR BOX ANNEALING A STEEL STRIP COIL AND FOR DECREASING THE STRAINS RESULTING IN THE SHEET FROM NON-UNIFORM ANNEALING WHICH COMPRISES FORMING A COIL OF A STEEL STRIP SUCH THAT AT LEAST ONE EDGE OF THE COIL HAS A PROJECTION THEREON WHICH IS PARALLEL TO THE WINDING AXIS OF THE COIL AND IS DISPOSED ABOUT THE CIRCUMFERENCE OF THE COIL TO PROVIDE A STABLE SUPPORT FOR THE COIL WHEN PLACED ON THE EDGE HAVING THE PROJECTION BY SWINGING THE STEEL STRIP LEFT AND RING DURING COILING, PLACING
US371984A 1972-06-23 1973-06-21 Box annealing of steel strip coils Expired - Lifetime US3898108A (en)

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JP47062360A JPS5213169B2 (en) 1972-06-23 1972-06-23

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BE (1) BE801284A (en)
DE (1) DE2331716C3 (en)
FR (1) FR2189520B1 (en)
GB (1) GB1425752A (en)
IT (1) IT989381B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4131417A (en) * 1977-06-15 1978-12-26 Aluminum Company Of America Carbon electrode production
US4427396A (en) 1981-02-16 1984-01-24 U.S. Philips Corporation Method of manufacturing a color selection electrode for a color display tube

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5527515U (en) * 1978-08-09 1980-02-22
JPS5914522B2 (en) * 1979-05-24 1984-04-05 新日本製鐵株式会社 Box annealing method for steel strip coil
JPS57101000A (en) * 1980-12-12 1982-06-23 Sumitomo Electric Ind Ltd Preparation of ceramic whisker
JPS57111300A (en) * 1980-12-25 1982-07-10 Sumitomo Electric Ind Ltd Preparation of ceramic whisker
JPS61295299A (en) * 1985-06-21 1986-12-26 Kobe Steel Ltd Preparation of silicon carbide whisker
JPS623098A (en) * 1985-06-21 1987-01-09 Kobe Steel Ltd Production of silicon carbide whisker
JPH0717369B2 (en) * 1987-10-20 1995-03-01 工業技術院長 Method for producing fibrous silicon / oxygen / carbon compound
JPH02217400A (en) * 1989-02-16 1990-08-30 Ofic Co Production of silicon carbide whisker

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2677538A (en) * 1950-11-09 1954-05-04 Asea Ab Method and apparatus for preventing piled sheet iron from sintering together during annealing
US2769630A (en) * 1954-03-19 1956-11-06 John D Keller Method for annealing tightly wound flat rolled metal stock
US3086729A (en) * 1960-06-29 1963-04-23 Nat Steel Corp Coiling apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2677538A (en) * 1950-11-09 1954-05-04 Asea Ab Method and apparatus for preventing piled sheet iron from sintering together during annealing
US2769630A (en) * 1954-03-19 1956-11-06 John D Keller Method for annealing tightly wound flat rolled metal stock
US3086729A (en) * 1960-06-29 1963-04-23 Nat Steel Corp Coiling apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4131417A (en) * 1977-06-15 1978-12-26 Aluminum Company Of America Carbon electrode production
US4427396A (en) 1981-02-16 1984-01-24 U.S. Philips Corporation Method of manufacturing a color selection electrode for a color display tube

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DE2331716B2 (en) 1975-03-06
JPS4922320A (en) 1974-02-27
JPS5213169B2 (en) 1977-04-12
FR2189520A1 (en) 1974-01-25
GB1425752A (en) 1976-02-18
FR2189520B1 (en) 1975-08-22
BE801284A (en) 1973-10-15
DE2331716C3 (en) 1975-10-09
DE2331716A1 (en) 1974-01-10
IT989381B (en) 1975-05-20

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