Classifications

• • 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
  • B21D1/05—Stretching combined with rolling

Definitions

• the present invention concerns a method for levelling strips, the thickness of which is maximum 4 mm, by simultaneous stretching and bending and by help of two levelling rolls only.
• Known levelling devices, fig 1 for levelling strips with a small thickness and widths, which can be considerable, is constituted in its central part of a number of zigzag-placed rolls 1 between which the strip 2 is passing and where the surface of the strip 2 is bended in two opposite directions.
• the strip 2 is subjected to a stretching in order to move the elastic zone from the centre of the strip at the bendjng around the levelling rolls 1.
• the main principle for the levelling of the strip 2 is to bring the material to exceed the yield point ⁇ s across the whole of its cross section in such a way that partly eventual buckles and others are removed, partly the strip leaving the last levelling roll without beeing bent.
• the strip is passing the levelling device, fig 1, under a pull effected by a tractive force of the coiling reel 3 and the braking force of the decoiling reel 4.
• Breaking rolls 5 are arranged on both sides of the levelling roll assembly to compensate changes in the pulling force in the strip 2 at changing outer diameters of the coils at coiling and decoiling. To get a good result a constant pull is required in the strip 2.
• the stretching force in the strip usually is adjusted in that way that a specific pulling force of 20-40 % of the yield point is reached in the strip.
• the diameter of the levelling rolls usually is dimensioned according to the unlevelty of the strip before levelling and the thickness of the strip.
• roller diameter is about 100 times the thickness t of the strip, but can of course vary within wide limits.
• a varying roller diameter in the assembly of levelling rolls also can be found.
• the drawbacks of conventional roller levelling assemblies is among others that these, because of a great number of levelling rolls, are complicated to adjust to get level strips and rather expensive in manufacturing. Also the plastic area of the strip is utilised into a too high degree because of a great number of bendings, which reduces the area of finishing of the material before reaching the breaking point and also hardens considerably because of the cold working.
• a radius R1 of the first levelling roll 1 is choosen, which because of earlier experiances from roller levelling devices shall be around or somewhat below 50 times the thickness t of the strip 2.
• a distance a is pointed out from the origin of coordinates along the abscissa, which distance is equal to the thickness t of the strip divided by the radius R1 of the first roll, and from that point a first parallel line 10 is drawn up against the plasticity line 9, parallel to the elasticity line 7.
• a first surface 11 is constituted in the diagram, fig 2, between the abscissa, the elasticity line 7, the first parallel line 10 and the plasticity line 9.
• a new second parallel line 12 is drawn to the right of the first surface 11 in that way that a second surface 13 between the abscissa, the first and the second parallel line 10, 12 and the plastcity line 9 becomes equal to the first surface 11.
• the distance b along the abscissa between the first and the second parallel line 10, 12 is measured.
• the thickness t of the strip 2 is devided with the later distance b which constitutes the radius R2 of the second levelling roll 1 in the rollsr levelling device, fig 1.

Landscapes

• Mechanical Engineering (AREA)
• Engineering & Computer Science (AREA)
• Straightening Metal Sheet-Like Bodies (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Stringed Musical Instruments (AREA)
• Treatment Of Fiber Materials (AREA)
• Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
• Decoration Of Textiles (AREA)
• Battery Electrode And Active Subsutance (AREA)
• Luminescent Compositions (AREA)
• Bending Of Plates, Rods, And Pipes (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20375919

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (1)

• 1989
  • 1989-05-11 SE SE8901686A patent/SE463605B/sv unknown
• 1990
  • 1990-05-09 AT AT90908320T patent/ATE94094T1/de not_active IP Right Cessation
  • 1990-05-09 DE DE90908320T patent/DE69003242T2/de not_active Expired - Fee Related
  • 1990-05-09 EP EP90908320A patent/EP0471777B1/en not_active Expired - Lifetime
  • 1990-05-09 DK DK90908320.6T patent/DK0471777T3/da active
  • 1990-05-09 WO PCT/SE1990/000311 patent/WO1990013372A1/en active IP Right Grant
• 1991
  • 1991-11-05 NO NO914335A patent/NO176046C/no not_active IP Right Cessation
  • 1991-11-11 FI FI915311A patent/FI915311A0/fi unknown

Non-Patent Citations (1)

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