Refrigeration – Display type – Plural storage compartments
Patent
1996-09-30
1999-01-12
Hail, III, Joseph J.
Refrigeration
Display type
Plural storage compartments
723662, 298953, B21B 3920
Patent
active
058573739
DESCRIPTION:
BRIEF SUMMARY
OBJECT OF THE INVENTION
The present invention relates to a method and a device for manufacturing cold rolled metal sheets or strips, through a cold rolling tandem mill or temper mill, in order to avoid the moire effect on the metal sheets or strips.
The present invention relates also to metal sheets or strips obtained through cold rolling tandem or temper mills by using the method and the device of the present invention.
STATE OF THE ART
The cold rolling process consists essentially in pulling off the strip coming from the hot rolling mill from the uncoiler through a tandem mill comprising usually several stands of 2, 4 or 6 high rolls and to coil it up again. The rolled strip coil is then heated up in a furnace, this process is known as annealing process. Afterwards, the annealed coil passes again through cold roll mill called skin pass or temper mill.
It is a common practice in cold rolling metal sheet to apply a certain roughness to the work rolls of the last stand of the tandem mill and/or of the temper mill.
The roughness is usually obtained by engraving the tandem or temper mill rolls through shot blasting or Electron Discharge Technology (EDT). The result of using such techniques is a stochastical roughness.
It is also known to use the laser technology for texturing rolls intended to cold rolling mills (see Fachberichte Huttenpraxis Metallweiterverarbeitung Vol. 23, No. 10, 1985, pp 968-972). This technique creates isolated craters with rims on the roll surface which are arranged in helicoidal pattern around the roll giving rise to periodic unidirectional phenomenon as far as the crater distances in the direction of the helix (roll circumference) are concerned.
The electron beam technology (EBT) can also be used in order to texture cold rolls for cold rolling tandem or temper mills. Advantageously, with this technique bidimensional periodic patterns (circumferential and axial) are produced, in which the unit cell is repeated as in a wall paper pattern.
It is common knowledge that when two periodic phenomena are superimposed, an interference is created having a different periodicity from the two composing phenomena, in the optical field, this is generally known as moire. When dealing with tandem and temper mill roll textures in the cold rolling process of metal sheet, the moire phenomenon occurs when more or less deterministic textures are applied to the rolls.
Shot blast technique does not give rise to moire, as the resulting textures are stochastic by nature. Laser, and electron beam (EBT) texturing and even EDT (electron erosion technique) are however subject to this optical interference pattern (see Journal of Materials Processing & a Manufacturing Science, volume 2, number 1, July 1993, p. 63, "Focused Energy Beam Work Roll Surface Texturing Science and Technology", L. G. Hector and S. Sheu).
During the cold rolling process, more can be created in two ways, when deterministic textures are used: or temper mill stand, i.e. when the upper and lower work rolls of a stand turn under load, touching each other, without a metal strip in between. During this process, the textures of both rolls are imprinted on each other, causing an unwanted moire pattern. Subsequently this moire pattern is transferred to the rolled sheet or strip, yielding a useless surface texture. tandem mill and subsequently, after annealing, in the temper mill, both mills being equipped with periodic textured rolls. The Superposition of the temper mill pattern on the existing tandem mill pattern can cause moire.
In "Gravures des cylindres de laminage a l'aide d'un. faisceau d'electrons" (A. Hamilus; ea, La Revue de Metallurgie--CIT Decembre 1992), there is mentioned that to avoid the moire effect between two deterministic patterns, it is necessary to rotate one pattern to the other over some degrees. This solution is technically not possible: the EBT texturing system is designed in such a way that the craters are always placed on parallel lines in the circumferential direction of the roll. Pivoting the pattern over some degrees
REFERENCES:
patent: 4866830 (1989-09-01), Zohler
patent: 4996113 (1991-02-01), Hector et al.
patent: 5025547 (1991-06-01), Sheu
patent: 5508119 (1996-04-01), Sheu et al.
patent: 5537851 (1996-07-01), Sheu et al.
patent: 5608969 (1997-03-01), Fields et al.
Revue De Metallurgie, vol. 89, No. 12, 1992, Paris FR pp. 1083-1091.
Hamilius "Gravures des cylindres de laminage a l'aide d'un faisceau d'electrons" see whole document.
De Mare Carl
Gadeyne Yves
Hail III Joseph J.
Sidmar N.V.
Tolan Ed
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