FR2605254A1 - LAMINATION PROCESS AND TRAIN FOR THE MANUFACTURE OF METAL STRIPS IN A LAMINATION PROCESS - Google Patents

Abstract

METHOD OF MANUFACTURING METAL STRIPS IN A LAMINATION PROCESS IN WHICH THE METAL TAPE IS TRAINED BY TENSION AND BENDING BEFORE A LAMINATION PASS, TENSILE AND BENDING DRESSING IN A COLD ROLLING PROCESS TAKING PLACE BEFORE THE FIRST STEP COLD ROLLED. THIS IS THEREFORE ELIMINATED "PINCHING", OR THE "PINCHING" EFFECT.

Description

The invention relates to a method of manufacturing metal strips in

  a rolling process in which the metal strip is drawn up by traction and forward bending

the rolling pass.

  For reduction passes as well as for dressing passes, difficulties arise when the supplied strip has undulations. The corrugated strip areas cause crush marks which deteriorate the strip and the cylinders. When the ripple is large enough, the waves collect in front of the right-of-way until they are folded down and laminated. For large cylinder diameters with a sufficient angle of attack,

  for example for duo rolling mills, the linings are laminated

  born, which makes the cylinders and the band unusable.

  For small cylinder diameters, for example for quarto rolling mills or rolling mills with multiple cylinders,

  the accumulation leads to the rupture of the strip or the cylinders

  dres. To avoid this so-called "pinching" effect, rolling is carried out with so high belt pulls that the plastic elongation of the strip occurs upstream of the narrowest right-of-way. The displacement of the flow limit line results in a greater elongation of the longitudinal strip areas compared to the longer wavy longitudinal strip areas so that the ripples are eliminated and the "pinching" effect is eliminated. These extremely high pulls of the web require additional devices, for example

  sets of traction rollers upstream of the cage

  minoir, which must be additionally trained by the

  cylinder drive mechanism. In addition, pull-ups

  extremely high band leads to aging-

  accelerated material.

  For finishing mills, for example laminates

  dressage blacks, it is however desirable for the ob-

  attention to the determined characteristics of the material, ef-

  carry out the deformation with the rolling mill with as little tension as possible on the strip, for example to obtain a well-defined grain in the area close to the surface. Empirical experiments indicate that rolling with

  weak pull-ups brings, as for the behavior called "anti

  floating ", a clear improvement for steels.- The question

  The extent to which this improvement is attributable to residual constraints of a different type, to a modification of the dislocations and to their density or to other action mechanisms remains unclear in a

large measure.

  Since undulations are inevitable during the production of strips, the aforementioned drawbacks of the well-known rolling processes manifest themselves in a particularly unfavorable manner for dressing rolling. In a completely different context, namely for

  the manufacture of thin metal strips from foil

  hot-rolled bacon in a hot-rolling process,

  it is known to draw up the hot rolled strip by trac-

  tion and bending before winding, dressing by traction and bending being carried out before the last hot rolling pass. The metal strip must therefore be produced,

  in a rational and economical way, with the mechanical qualities

  niques, metallurgical and geometric of a cold rolled metal strip, in a continuous hot rolling process

  while avoiding in particular pronounced rolling textures.

  These well-known measures did not allow an exercise

  decisive influence on the problems described above

  and encountered during the cold rolling of metal strips.

  The object of the present invention is to indicate a process for manufacturing metal strips of the aforementioned type which makes it possible, during cold rolling, to eliminate the "pinching" effect by employing extremely high tensile forces.

weak of the band.

  According to the invention, this object is achieved by the fact that, in a process of this type, dressing by traction and bending is carried out in a cold rolling process.

  before the first cold rolling pass. The invention re-

  posits on the discovery that, during dressing by traction and bending, the metal strip to be cold rolled is folded alternately under traction on several traction and bending rollers of small diameter, the traction and bending forces being added on the respective traction and bending rollers. The efforts required for stretching are provided not only by the traction of the

  strip, but mostly by superimposed bending.

  The advantage of straightening by traction and bending also resides, in addition to the relatively weak traction of the strip itself

  for large sheet sections, in real flatness

  sand the metal strip in such a way that the undulations

  tions are also eliminated at the same time. After the dres-

  wise by traction and bending, the metal strip is

  put, with now the same lengths of "fibers", in the cold rolling process. Therefore, the "pinching" effect is eliminated. Damage to the metal strip and

  cylinders are avoided while obtaining the effect of lami-

  desired swim. We also see the possibility of acting

  in a controlled manner on the stretch limit, the deformability

  lity and aging of the metal strip. The process

  according to the invention is particularly suitable for

  tagger for processing lines, for example annealing lines, galvanizing lines or the like, in which the metal strip in question is ironed or rolled up. In such processing lines, the cold rolled metal strip is annealed

  soft in annealing ovens, which can cause

  ripples following the dissolution of con-

  traces, uneven residuals in the band plane but

which are now eliminated.

  The invention also relates to a rolling mill train which is particularly suitable for implementing the claimed process and which comprises at least one rolling mill stand and a straightening stand by traction and bending mounted upstream.

  of the rolling stand. This rolling mill train is characterized

  se by the fact that the rolling mill stand is shaped as a cold rolling mill, for example as a duo, quarto or multi-roll rolling mill. The diameter of the dressing rollers by traction and bending can then be 30 to 40 times the thickness of the strip before the first rolling pass.

Cold.

  The following description, next to the drawings

  appended as nonlimiting examples, will allow

  understand how the invention can be put into practice.

  Figure 1 is a diagram of a rolling mill train

  with a quarto cage for the implementation of the following process

  before the invention. Figure 2 is a diagram of a cold rolling train with a duo cage for the implementation of the process

  according to the invention, in an annealing line.

  FIG. 1 shows a rolling mill train with at least one rolling stand 1, namely a quarto stand, and a drawing and bending dressing stand 2 mounted upstream of the rolling stand 1, as well as with an unwinder 3 and one

  reel 4 for the metal strip 5. The quarto cage con-

  titues the rolling mill stand 1. The diameter of the dressing rollers 6 by pulling and bending the stand 2 mounted upstream is equal to 30 to 40 times the thickness of the strip

  before the first rolling pass.

  FIG. 2 shows an annealing line with an annealing oven 7 followed by a cooling zone 8 and a reserve 9 of strip with a looper carriage. Between the cooling zone 8 and the strip reserve 9 is disposed a duo rolling stand preceded by a dressing stand 2 by traction and bending. Upstream of the cage 2 can be arranged braking rollers 10. In all cases, the duo rolling mill cage is also shaped as a

cold rolling mill 1.

  In the two embodiments, dressing by traction and bending in the context of a cold rolling process takes place before the first cold rolling pass so that, during the cold rolling of the metal strip 5 considered, the "pinching" or clamping / pinching effect is eliminated with the use of extremely weak pulls on the strip. It results from the weak pulls of the strip a controlled aging or

  extremely delayed from the web material.

Claims (4)

  1. Method for manufacturing metal strips in a rolling process in which the metal strip is drawn by tension and bending before the rolling pass, characterized in that the drawing by tension and bending in a cold rolling process is done before the first rolling pass.   2. Method according to claim 1, characterized in that the dressing by traction and bending is carried out before ironing with a rolling mill or the dressing of the metal strip in a treatment line, for example a   annealing, galvanizing line or similar installation.   3. Rolling mill train for implementing the process   die according to one of claims i or 2, comprising at least   a rolling stand (1) and a dressing stand (2) by   traction and bending mounted upstream of said laminate cage   black (1), characterized in that the rolling mill stand is shaped like a cold rolling stand (1), for example   in duo, quarto or multi-cylinder cages.   4. Rolling mill train according to claim 3, charac-   terrified by the fact that the diameter of the dressing rollers   (6) by traction and bending is 30 to 40 times the thickness   strip before the first rolling pass.