US20050048216A1 - Method for hot-dip finishing - Google Patents

Method for hot-dip finishing Download PDF

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Publication number
US20050048216A1
US20050048216A1 US10/490,780 US49078004A US2005048216A1 US 20050048216 A1 US20050048216 A1 US 20050048216A1 US 49078004 A US49078004 A US 49078004A US 2005048216 A1 US2005048216 A1 US 2005048216A1
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United States
Prior art keywords
strip
rotors
accordance
molten metal
coating
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.)
Abandoned
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US10/490,780
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English (en)
Inventor
Rolf Brisberger
Walter Trakowski
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SMS Siemag AG
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Individual
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Filing date
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Assigned to SMS DEMAG AG reassignment SMS DEMAG AG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BRISBERGER, ROLF, TRAKOWSKI, WALTER
Publication of US20050048216A1 publication Critical patent/US20050048216A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
    • C23C2/24—Removing excess of molten coatings; Controlling or regulating the coating thickness using magnetic or electric fields

Definitions

  • the invention concerns a method for coating the surface of a product, especially a strip-shaped product, for example, nonferrous metal strip or steel strip, with at least one metal coating by passing the product through at least one molten metal bath space that contains the molten coating material.
  • the invention also concerns a device for carrying out the method.
  • Method 1 In conventional hot dip coating of strip (referred to here as Method 1) with Zn, Zn—Al, Al, or Al—Si alloys, the strip runs in the coating section from an annealing furnace under conditions of air exclusion into the molten metal and is deflected vertically and stabilized by various arrangements of nondriven rollers (see FIG. 1 ). This applies to all of the specified coating metals/alloys used in hot dip coating.
  • a disadvantage of Method 1 is that the rollers and the bearings of the rollers are located within the molten material, and all parts are exposed to chemical attack by the molten material. The service life of the parts that are used within the molten material is limited. In addition, a large volume of molten material with a correspondingly large dip bath is necessary to accommodate the rollers and all of the bath equipment. 200 to 400 t of molten zinc are customary in hot dip galvanizing. Due to this large volume, rapid regulation of the temperature and alloy composition of the melt is not possible. Large fluctuations of the specified parameters must be accepted and sometimes result in loss of quality, since measures related to the production of the alloy and those related to influencing the strip quality are carried out in the same tank and thus affect one another.
  • Another disadvantage is that the production speed cannot be increased to realize an economical plant output (about 180 m/min), especially in the case of thin strip ⁇ 0.5 mm.
  • One reason for this is that relative motion can develop between the rollers located in the bath and the strip. If the tension is increased in an effort to avoid this problem, there is the risk of strip breakage. This results in scrap and prolonged plant shutdowns.
  • the jet stripping system located above the zinc hot dip bath further limits the maximum strip advance speed of a hot dip galvanizing installation (see FIG. 1 ).
  • the coating thickness is adjusted by air or nitrogen, and the minimum coating thickness that can be produced increases with increasing strip speed. This means that thin coatings cannot be produced at high strip speeds. However, certain demanding applications require thin coatings ( ⁇ 25 g/m 2 on one side in hot dip galvanized sheet).
  • So-called vertical hot dip galvanizing is well known as an advanced method for the hot dip coating of ferritic steel strip made of soft unalloyed steels and is described in various patents, such as EP 0 630 421 B1, EP 0 630 420 B1, and EP 0 673 444 B1.
  • Method 2 the strip passes from bottom to top through a working tank filled with molten metal composed of zinc and/or Al alloys after it has been subjected to a heat treatment.
  • the strip enters the molten bath under conditions of air exclusion.
  • the volume of molten metal (about 2-5 t of molten zinc) is much smaller than in Method 1.
  • the working tank and the furnace chamber located below it are connected by a gastight ceramic duct, which is about 800 mm high and has a passage width for the strip of only a maximum of 20 mm.
  • the working tank is sealed at the bottom to prevent molten metal from flowing down into the furnace chamber by means of a seal produced within this duct by two inductors arranged at the side of the duct or strip. These inductors induce an electromagnetic traveling field, which produces an upwardly directed force that prevents the molten metal from flowing down.
  • This inductive system acts like a pump, so that exchange of the melt in the duct is ensured.
  • Method 2 is characterized by the fact that, at least in the coating area up to the hot dip bath, significantly higher strip speeds on the order of 300 m/min can be realized even with thin steel strip, since there are no rollers in the coating tank.
  • the desired thickness of the metal coating is adjusted a short distance above the hot dip bath by the jet stripping process, as in Method 1. This process is comparable to the process used in Method 1 and involves the blowing of compressed air or nitrogen.
  • Method 2 As in Method 1, the jet stripping process in Method 2 also limits the maximum possible strip speed when thin coatings are being applied. However, Method 2 offers greater degrees of freedom for the galvanizing parameters of melt temperature and viscosity and alloy composition, which likewise affect the coating thickness. For this reason, it is to be expected that a higher strip speed can be selected in Method 2 than in Method 1 for the same coating thickness. In contrast to Method 1, Method 2 has not yet been tested on the industrial scale. So far only pilot plant trials with narrow strip have been conducted. These trials were successful.
  • the cooling is usually produced by several successive air cooling lines.
  • the cooling effect or, more precisely, the cooling rate is limited by the medium and cannot be increased at will on a fixed length of line (e.g., two times 15 m) with the use of air as the cooling medium.
  • the cooling lines With increasing strip speed or with increasing mass throughput, the cooling lines must be lengthened. However, it then becomes necessary to raise the upper deflecting roller in the cooling tower of a hot dip coating installation.
  • the height of the upper deflecting roller is usually 30-60 m.
  • the objective of the present invention is to avoid the specified disadvantages of Methods 1 and 2 and to create a high-speed hot dip coating installation without a cooling tower, which combines the least possible construction expense with optimized capital investment costs and high plant output with the best production quality.
  • FIG. 1 shows a conventional strip coating method
  • FIG. 2 shows an advanced coating method in accordance with the state of the art.
  • FIG. 3 shows the coating method of the invention and a correspondingly designed high-speed hot dip coating installation in operation.
  • FIG. 4 shows the installation in FIG. 3 in a start-up situation.
  • FIG. 5 shows the installation in FIG. 3 during shutdown after operation.
  • strip 1 runs vertically downward into a molten metal bath space that contains the hot dip bath.
  • This hot dip bath is sealed towards the bottom.
  • forces but these forces are not electromagnetic in nature, but rather are produced by rotating permanent magnets.
  • the sealing of the melt with permanent magnets is well known in itself, but the prior art involved the use of rectangular ducts. A duct shape like this cannot be changed with respect to clearance and shape.
  • the present invention proposes two adjacent rotors 5 , 5 ′.
  • the rotors are tubes 6 , 6 ′ made of materials that are resistant to heat and molten metal, preferably ceramic materials. Rollers, on whose cylindrical surface permanent magnets 4 are mounted, rotate inside these tubes 6 , 6 ′, whose diameters may be freely selected.
  • the rotors 5 , 5 ′ can be adjusted to the melt or to the strip. It is also possible to close the gap 7 when the installation is shut down or is being started up.
  • Permanent magnets are significantly less expensive than electromagnetic sealing by means of coils or inductors, and much less power is required for the rotation than for an electromagnetic seal, which is an advantage especially in the event of a power failure.
  • the strip can be supported at much shorter lengths than in the previously known Methods 1 and 2, since the strip 1 can be immediately cooled and deflected into a water bath 9 directly below the sealing unit.
  • the support length in the present invention is preferably only about 5,000 mm, whereas in Method 1 it is about 8-10 times greater, and in Method 2 it is greater still.
  • the surface of the molten metal, preferably the molten zinc, in the coating area is within a protective gas atmosphere, which preferably consists of a nitrogen/hydrogen mixture, so that interfering oxidation of the molten zinc cannot occur.
  • a protective gas atmosphere which preferably consists of a nitrogen/hydrogen mixture
  • the incoming strip 1 to be coated passes through a tension roller 17 and then through a lock 18 , which hermetically seals the protective gas atmosphere prevailing inside the hot dip coating installation from the ambient, oxygen-containing atmosphere.
  • the strip 1 In the galvanizing chamber 14 which follows, the strip 1 is vertically deflected by guide rollers 13 towards the coating section 19 . Upon entering the coating station 19 , the strip 1 passes vertically from top to bottom through the bath of molten metal 3 maintained in the gap 7 between the rotors 5 , 5 ′ and thus receives the desired coating.
  • this hot dip bath 3 in a gap formed between spaced rotors 5 , 5 ′, the molten metal is prevented from running out at the bottom by magnetic forces of magnetic fields or traveling magnetic fields of the rotating permanent magnets 4 .
  • the rotors 5 , 5 ′ are located inside the tubes 6 , 6 ′ that surround them.
  • the coating station 19 is surrounded on the outside by a duct-like housing and holds the rotors 5 , 5 , which are spaced a variable distance apart. They are surrounded by the tubes 6 , 6 ′, which are made of materials that are resistant to heat and molten metal, especially nonmagnetic materials and preferably ceramic materials.
  • the permanent magnets 4 rotate inside these tubes 6 , 6 ′.
  • the molten metal required for coating which must be continuously replenished, is conveyed in controlled amounts by a metal pump 12 from a reservoir 8 , in which it is conditioned, into the gap 7 between the rotors 5 , 5 ′.
  • the strip 1 which is coated in the gap 7 , passes through the gap at the lower end and then passes in succession through an arrangement 15 for air stabilization and an arrangement 16 for water cooling.
  • FIGS. 4 and 5 show the method of the invention

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Coating With Molten Metal (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
US10/490,780 2001-09-28 2002-09-25 Method for hot-dip finishing Abandoned US20050048216A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10148158A DE10148158A1 (de) 2001-09-28 2001-09-28 Verfahren zur Schmelztauchveredelung mit umgekehrtem Bandlauf
DE1048158.6 2001-09-28
PCT/EP2002/010741 WO2003029507A1 (de) 2001-09-28 2002-09-25 Verfahren zur schmelztauchveredelung

Publications (1)

Publication Number Publication Date
US20050048216A1 true US20050048216A1 (en) 2005-03-03

Family

ID=7700812

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US10/490,780 Abandoned US20050048216A1 (en) 2001-09-28 2002-09-25 Method for hot-dip finishing

Country Status (18)

Country Link
US (1) US20050048216A1 (de)
EP (1) EP1430162B1 (de)
JP (1) JP2005504177A (de)
KR (1) KR20040045011A (de)
CN (1) CN1295373C (de)
AT (1) ATE327352T1 (de)
BR (1) BR0212938A (de)
CA (1) CA2461912A1 (de)
DE (2) DE10148158A1 (de)
ES (1) ES2264738T3 (de)
HU (1) HUP0401759A2 (de)
MX (1) MXPA04002746A (de)
PL (1) PL367442A1 (de)
RU (1) RU2300577C2 (de)
UA (1) UA78722C2 (de)
WO (1) WO2003029507A1 (de)
YU (1) YU25704A (de)
ZA (1) ZA200401565B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050115052A1 (en) * 2002-09-13 2005-06-02 Hideyuki Takahashi Method and apparatus for producing hot-dip coated metal belt
US20130029055A1 (en) * 2010-04-13 2013-01-31 Fives Stein Method and device for coating metal strips

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10240954B4 (de) * 2002-09-05 2012-05-31 Sms Siemag Aktiengesellschaft Vorrichtung zur Schmelztauchbeschichtung eines Metallstranges

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2223499A (en) * 1936-08-20 1940-12-03 Crown Cork & Seal Co Method of coating metal
US3939799A (en) * 1973-07-17 1976-02-24 Nippon Kokan Kabushiki Kaisha Magnetic force sealant for plating tank
US5384166A (en) * 1991-06-25 1995-01-24 Nkk Corporation Method for controlling coating weight on a hot-dipped steel strip

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE328454B (de) * 1968-09-20 1970-09-14 Asea Ab
JPS63286562A (ja) * 1987-05-19 1988-11-24 Hitachi Cable Ltd 溶融めっき方法
DE3718178A1 (de) * 1987-05-29 1988-12-15 Hoesch Stahl Ag Verfahren zur herstellung von metallischen fasern und vorrichtung zu dessen durchfuehrung
IN191638B (de) * 1994-07-28 2003-12-06 Bhp Steel Jla Pty Ltd
JPH1017184A (ja) * 1996-07-01 1998-01-20 Nippon Steel Corp 鋼帯の搬送ロール
JPH1143754A (ja) * 1997-07-23 1999-02-16 Nisshin Steel Co Ltd 溶融めっき金属の流下防止機構を備えた空中ポット
JPH11172400A (ja) * 1997-12-15 1999-06-29 Hitachi Ltd 連続溶融金属めっき装置及び連続溶融金属めっき方法
CN2332733Y (zh) * 1998-07-17 1999-08-11 张玉崑 使用电磁力抹制的金属线材热镀钢丝设备
JP2000212714A (ja) * 1999-01-18 2000-08-02 Hitachi Ltd 連続溶融金属めっき装置及び連続溶融金属めっき方法
JP2000219944A (ja) * 1999-01-29 2000-08-08 Nkk Corp 溶融金属メッキ鋼帯の製造装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2223499A (en) * 1936-08-20 1940-12-03 Crown Cork & Seal Co Method of coating metal
US3939799A (en) * 1973-07-17 1976-02-24 Nippon Kokan Kabushiki Kaisha Magnetic force sealant for plating tank
US5384166A (en) * 1991-06-25 1995-01-24 Nkk Corporation Method for controlling coating weight on a hot-dipped steel strip

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050115052A1 (en) * 2002-09-13 2005-06-02 Hideyuki Takahashi Method and apparatus for producing hot-dip coated metal belt
US7617583B2 (en) * 2002-09-13 2009-11-17 Jfe Steel Corporation Method for producing hot-dip coated metal belt
US20130029055A1 (en) * 2010-04-13 2013-01-31 Fives Stein Method and device for coating metal strips
US9109833B2 (en) * 2010-04-13 2015-08-18 Fives Stein Method and device for coating metal strips

Also Published As

Publication number Publication date
CA2461912A1 (en) 2003-04-10
WO2003029507A1 (de) 2003-04-10
CN1295373C (zh) 2007-01-17
RU2300577C2 (ru) 2007-06-10
EP1430162A1 (de) 2004-06-23
DE10148158A1 (de) 2003-04-17
RU2004113102A (ru) 2005-05-20
EP1430162B1 (de) 2006-05-24
ATE327352T1 (de) 2006-06-15
ES2264738T3 (es) 2007-01-16
CN1561404A (zh) 2005-01-05
JP2005504177A (ja) 2005-02-10
PL367442A1 (en) 2005-02-21
HUP0401759A2 (en) 2004-12-28
KR20040045011A (ko) 2004-05-31
YU25704A (sh) 2006-08-17
BR0212938A (pt) 2004-10-13
ZA200401565B (en) 2004-05-04
MXPA04002746A (es) 2005-09-08
DE50206923D1 (de) 2006-06-29
UA78722C2 (en) 2007-04-25

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AS Assignment

Owner name: SMS DEMAG AG, GERMANY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BRISBERGER, ROLF;TRAKOWSKI, WALTER;REEL/FRAME:015659/0938

Effective date: 20040308

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION