JOINING METHOD OF HIGH CARBON STEEL FOR ENDLESS HOT ROLLING AND THE APPARATUS THEREFOR

• US 20110174869A1
• Filed: 11/20/2006
• Published: 07/21/2011
• Est. Priority Date: 12/26/2005
• Status: Active Grant

• Current Assignee: Primetals Technologies Japan, Ltd. (Mitsubishi Heavy Industries, Ltd.), POSCO Co. Ltd. (Posco Holdings Incorporated)
• Original Assignee: Mitsubishi-Hitachi Metals Machinery Incorporated (Mitsubishi Heavy Industries, Ltd.), Posco Holdings Incorporated
• Inventors: Furumoto, Hideaki, Kang, Youn-Hee, Won, Chun-Soo, Funamoto, Takao, Horii, Kenji, Lee, Jong-Sub, Shirogane, Shigenori, Usugi, Toshihiro, Lee, Jong-Bong, Ha, Sang-Wook
• Granted Patent: US 8,584,923 B2
• Time in Patent Office: Days
• US Class Current: 228/265
• CPC Class Codes: B23K 20/02 by means of a press ; Diffusion bonding B23K20/001, B23K20/04 take precedence
• CPC Class Codes: B23K 20/028 Butt welding
• CPC Class Codes: B23K 2101/16 Bands or sheets of indefinite length

Abstract

An endless hot rolling material shear-joining method capable of threading hot rolling materials in a finish rolling process without strip breakage by controlling joining conditions for the hot rolling materials in an endless hot rolling process for high carbon steel, and an endless hot rolling plant therefor are disclosed. The shear-joining method for endless hot rolling materials of high carbon steel includes shear-joining high carbon steel metal bars comprising, in terms of weight %, 0.30% to 1.20% C, inevitable impurities, and balance Fe, or comprising 0.15% to 1.5% C containing at least one of Cr, Ni, Mo, V, Ti, W, B, Nb, and Sb, inevitable impurities, and balance Fe, such that a joined surface of the joined metal bars is formed to be inclined in a thickness direction of the metal bars, in a hot rolling plant by a joiner adapted to join the metal bars after overlapping tail part of a leading one of the metal bar and top part of a trailing metal bar.

Claims

1. A shear-joining method for endless hot rolling materials of high carbon steel comprising:

shear-joining high carbon steel metal bars comprising, in terms of weight %, 0.30% to 1.20% C, inevitable impurities, and balance Fe, or comprising 0.15% to 1.5% C containing at least one of Cr, Ni, Mo, V, Ti, W, B, Nb, and Sb, inevitable impurities, and balance Fe, such that a joined surface of the joined metal bars is formed to be inclined in a thickness direction of the metal bars, in a hot rolling plant by a joiner adapted to join the metal bars after overlapping tail part of a leading metal bar and top part of a trailing metal bar.

2. The shear-joining method according to claim 1, wherein portions of the metal bars to be joined are descaled at a pressure of 50 MPa or less.

3. The shear-joining method according to claim 1, wherein the shear-joining of the metal bars is executed under a condition in which a lap representing an overlap distance between upper and lower blades of the joiner ranges from 2 mm to 18 mm.

4. The shear-joining method according to claim 1, wherein the shear-joining of the metal bars is executed under a condition in which a stroke ratio representing a value obtained after dividing a sum of moved distances of upper and lower blades of the joiner by a thickness of the metal bars ranges from 1.3 to 1.7.

5. The shear-joining method according to claim 4, wherein the shear-joining of the metal bars is executed under the condition in which the upper and lower blades of the joiner move simultaneously in upward and downward directions.

6. The shear-joining method according to claim 4, wherein the shear-joining of the metal bars is executed under the condition in which only one of the upper and lower blades of the joiner moves.

7. The shear-joining method according to claim 2, wherein the shear-joining of the metal bars is executed under a condition in which a lap representing an overlap distance between upper and lower blades of the joiner ranges from 2 mm to 18 mm.

8. The shear-joining method according to claim 7, wherein the shear-joining of the metal bars is executed under a condition in which a stroke ratio representing a value obtained after dividing a sum of moved distances of the upper and lower blades of the joiner by a thickness of the metal bars ranges from 1.3 to 1.7.

9. The shear-joining method according to claim 2, wherein the shear-joining of the metal bars is executed under a condition in which a stroke ratio representing a value obtained after dividing a sum of moved distances of upper and lower blades of the joiner by a thickness of the metal bars ranges from 1.3 to 1.7.

10. A hot rolling plant comprising:

a rough rolling mill for rough rolling high carbon steel slabs comprising, in terms of weight %, 0.30% to 1.20% C, inevitable impurities, and balance Fe, or comprising 0.15% to 1.5% C containing at least one of Cr, Ni, Mo, V, Ti, W, B, Nb, and Sb, inevitable impurities, and balance Fe, to produce rough-rolled metal bars;

a coil box for winding the rough-rolled metal bars in the form of coils;

a descaling apparatus for descaling portions, to be overlapped, of the metal bars unwound from a coiler of the coil box;

a shear-joining apparatus including a pair of shearing blades for overlapping tail part of a leading one of the metal bars and top part of a trailing metal bars, pressing the overlapped portions toward each other while clamping the overlapped portions, to shear the overlapped portions, thereby shear-joining the metal bars; and

a finish rolling mill for finish rolling the resultant shear-joined metal bar.