EP1669141B1 - Process for the control of the cross-section of wires running out from a wire rolling mill and metal wire rolling mill - Google Patents

Abstract

Controlling the cross-section of wire strands leaving a wire rod mill comprises carrying out drawing for the cross-sectional changes in front of the last common drive group of a roll stand so that the wire with a uniform cross-section leaves the roll stand, preferably a finished roll stand. An independent claim is also included for a wire rod mill for carrying out the control method.

Description

The invention relates to a method for controlling the cross section of emerging from a wire rod wire strands, in which the brought up from an intermediate wire rod of a finishing stand assembly and this optinal subsequent Nachwalzgerüstanordnung is supplied, wherein the cross section of the wire strand is changed during the rolling process by controlled Zugbeaufschlagung. In addition, it relates to a wire rod mill for carrying out the method.

The industry today demands tolerances from modern wire rolling mills, which are virtually no longer attainable with conventional design of the wire rod with manual corrections of their settings. Both narrow and over the entire length of the wire strand at most minimally varying deviations are required or tolerated. The tolerances behind the finished wire block are determined by many parameters. Great influence on the tolerances of the incoming in the finished block or the finished scaffold assembly cross section of the wire strand and its inlet temperature. These cross-sectional and temperature fluctuations result in tensile fluctuations in the finished block, which in turn results in tolerance fluctuations behind it. The inlet cross section in the finished block depends inter alia on the train in the upstream intermediate road or in a bloc. The rolling conditions do not remain constant during the rolling of the rod, but constantly change during the rolling. Under these Rolling conditions are especially the parameters inlet cross section, temperature and longitudinal train of importance, which lead to cross-sectional fluctuations.

In order to achieve good tolerances despite these constantly varying rolling conditions, the bloom settings would have to be permanently adapted to the respective rolling conditions. However, this is extremely difficult in practice, especially in group drive of the rolls of the rolling stands only the nip, but not the speeds are correctable. With the systems known hitherto, attempts have been made to ensure the negative influence of the interference factors on the finished tolerances with the aim of creating a constant outlet cross section of the wire from the finishing stand arrangement by controlling a likewise constant inlet cross section of the wire in the finishing stand arrangement.

So it is from the EP 200 396 B1 known to arrange in front of the finishing stand arrangement in the rolling direction two sizing stands whose speeds are controlled so that together with the scaffolding a train is created, which has a corresponding reduction of the wire cross-section result and makes it possible to have a constant end cross-section of the in the To control the finishing stand arrangement of incoming wire.

The invention is therefore an object of the invention to provide a control method and a wire rod of the type mentioned, which allow in a simple manner to adapt the wire production to the varying rolling conditions and independently of these provide an optimal finished cross-section of the wire or billet.

This object is achieved with the features stated in the main method claim and the main device claim relating to a wire rod mill. Advantageous embodiments of the fully automatic running control method and the wire rod mill are included in the dependent claims.

The invention is based on the finding that, unlike the known rolling mill training, a constant outlet cross section of the finished stand arrangement or, if present, the wire strand emerging from a Nachwalzgerüstanordnung (Nachwalzblock) can be determined due to change in the inlet cross section of the wire in the respective framework arrangement , The tension control of the wire strand can here at any point and in extreme cases even before a last drive or single group, d. H. take the last rolling.

This can be achieved according to the invention by measuring and comparing the wire cross sections, preferably in front of and behind the finishing stand arrangement, and changing the inlet cross section of the wire by pulling forces applied to the incoming wire. As is known, these tractive forces can be applied to the wire by pairs of variable-speed horizontal and vertical stands arranged in front of the finishing stand arrangement. However, according to the invention, a piston-cylinder unit can also be arranged between the two rolling stands, on whose piston, which can be controlled via a displacement sensor, a tensioning roller acting upon the wire-strand can be arranged. In addition, can be arranged in front of and behind the horizontal and vertical roller pair and behind the finishing stand assembly or the Nachwalzgerüstanordnung profile measuring devices and also in front of these scaffolds and in front of the finishing stand assembly or the Nachwalzgerüstanordnung pyrometer.

Thus, when both a profile measuring system and a temperature measuring device are provided in front of the stands, the cross section A ₀ and the temperature T ₀ can be measured. For a defined type of steel and temperature T ₀ , as shown in FIG. 3, including the reference numeral list, be constructed by correlations between A ₀ and A _1, a "feed forward". It can thus be achieved that the first billet or wire strand of a new batch is within a permissible tolerance range.

The invention enables an adaptive cross-sectional control (AQR) as a hierarchical sizing system, which ensures the best possible finished cross-section, with minimal tolerances, at all times by means of a continuous adaptation of the puncture cross-section, regardless of the constantly changing rolling conditions. The AQR assumes that all subordinate rules or measurements, ie. H. Position Tensile Measurement (PZM), Position Tensile Control (PZR), and Position Cross Section Control (PQR) are active.

To realize a slow "backward control", as shown in Fig. 4, including the reference numeral list, a Profilmeßgerät is required behind the rolling mill assembly. It is the round width, ie the caliber filling behind the rolling stand assembly used as a control variable for the cross-sectional control before the roll stand. The cross section A ₁ is varied by a variable train F _z (t) between the scaffolds 1 and 2 in A ₁ (t) that there is behind the roll stand optimal caliber filling and thus a constant width in the cross section A ₂ and thus a good Ovality exists.

If a fast "backward regulation" is to be realized as an option, as illustrated in FIG. 5 with reference to the reference list, a profile measuring device or system must also be provided in front of the first stand of the rolling stand arrangement. By a product to product adaptation, with the same steel grades and temperatures T ₁ and T ₂ in the wire train and by correlations between the cross sections A ₁ and A ₂ and adaptation values, the control intervention can be advanced. Thus, a cross-sectional control is built with a high dynamic, which ensures that the fluctuations in the caliber filling, and consequently the ovality, are minimal.

In the case of adaptation with the slow "backward control", this only serves to correct system errors and trends.

Finally, it is also possible to influence the cross section of the wire entering the finishing stand arrangement even in the finishing stand arrangement itself, before leaving the latter, by controlling that the finishing stand arrangement consists of a sequence of stand groups, the rolls which can be set for themselves and / or for have drivable rollers.

Figur 1

in schematischer Darstellung als Einzelheit eine Vorrichtung zur Zugbeaufschlagung des Drahtstranges, von der Seite gesehen;

Figur 2

die Seitenansicht einer Drahtwalzstraße, in schematischer Darstellung, mit einer einem Fertigblock vorgeschalteten Zugbeaufschlagungseinrichtung nach Fig. 1;

Figur 3

in schematischer Darstellung eine Anordnung zur Adaptiven Querschnitts-Regelung als "Vorwärtsregelung";

Figur 4

in schematischer Darstellung eine Anordnung zur Adaptiven Querschnitts-Regelung als langsame "Rückwärtsregelung"; und

Figur 5

in schematischer Darstellung eine Anordnung zur Adaptiven Querschnitts-Regelung als schnelle "Rückwärtsregelung".

The invention will be explained in more detail with reference to the embodiments shown in the drawing in connection with a arranged before a finishing stand assembly / finished block Zugbeaufschlagungseinrichtung in the wire rolling. Show it:

FIG. 1

in schematic representation as a detail of a device for Zugbeaufschlagung the wire strand, seen from the side;

FIG. 2

the side view of a wire rolling mill, in a schematic representation, with a pre-finished block pre-tensioning device according to Fig. 1;

FIG. 3

a schematic representation of an arrangement for adaptive cross-section control as "feed forward";

FIG. 4

a schematic representation of an arrangement for adaptive cross-section control as a slow "backward control"; and

FIG. 5

a schematic representation of an arrangement for adaptive cross-section control as a fast "backward control".

The arrangement for tension measurement and for loading the wire of Fig. 1 consists of a between the rollers of a vertical horizontal roller pair VW, HW, of which the vertical roller pair VW has a variable speed drive DR, arranged piston cylinder unit KZ, on the piston rod KS a tension roller SR stores , which acts on the continuous wire strand DS from below. The piston cylinder KZ as a hydraulic or pneumatic control cylinder is connected to a force transducer KA and a displacement sensor WG. With this arrangement, the section of the wire strand between the roller pairs VW, HW can be selectively biased and the amount of deflection of the wire strand DS can be determined and measured. The measurement, control and cross-sectional control serving measuring and control cylinder unit is shown in simplified dash-dotted lines.

1, in the rolling direction WR behind this a profile measuring device PMI and further in the rolling direction WR behind the finished block FB on another profile measuring device PMII on the wire drawing apparatus of Fig. 2. In addition, in the rolling direction WR behind the Zugbeaufschlagungseinrichtung described above and behind the finished block each pyrometer PYI and PYII are arranged.

For the method of controlled variation of the input cross-section of the wire strand DR in the finished block FB by tensile forces applied to the wire, the device of Figure 1 is used. This works as follows: After entry of the beginning of the wire strand DS, the tension roller SR is driven upwards by the piston cylinder KZ against the wire strand DS, so that this undergoes a deflection, the dimension of which forms the basis for the clamping force, the value continuously recorded and stored a computer and train control device is supplied. Since the tension exerted on the wire rod DR is a function of the tension and deflection of the wire under the tension roller SR he controlled and regulated by means of a position control of the tension roller under the position sensor WG. By controlling a constant train between the vertical and horizontal rollers VW, HW cross-sectional errors of the wire strand DS can be eliminated and achieve a relatively constant inlet cross section in the finishing stand assembly FB with the result of an optimal exit or finished cross section of the arrangement.

With the reproduced in Figure 2 training a wire rod two modes for carrying out the method according to the invention are possible, namely the Zugbeaufschlagung via a speed control or a deflection.

In the deflection control, a set deflection is specified and their size is optimized depending on the cross section. By a product-dependent deflection, the ratio between tensile force and clamping force can be optimized. In order to achieve the reference value of the clamping force, the speed at the tension-controlled stand VW is corrected until the clamping force, d. H. also the current train reaches the given reference value. Thereafter, the clamping force is kept constant by further speed corrections.

In the case of speed control, in order to achieve the reference value of the clamping force, the deflection is controlled in such a way that the reference value and thus also the traction force are achieved and kept as constant as possible. In order to work in an optimal train range, speed corrections are made on the tension-controlled scaffold VW. The speed of the scaffolds VW and HW is not changed in this case.

Another operating mode is based on the respective measurable cross section of the wire strand. Measuring means are the profile measuring devices PMI shown in Figure 2 behind the vertical, horizontal roller pair VW and HW of the arrangement of FIG 1 and behind the finishing stand arrangement or the finished block FB according to FIG. 2. The prerequisite for this cross-sectional regulation is tension control. If the tip of the wire rod DS passes the horizontal rolling stand HW, the tension control is activated first. If the tip then passes the profile measuring system PMI, the rolling stock cross section is continuously measured before the finishing stand arrangement FW and parameters relevant to the regulation, such as profile width and height, are passed on to the computer, not shown, and displayed on the monitor. The cross-section control uses the tension between the two scaffolds VH and HW to optimize the outlet cross-section of these scaffolds. The controlled variable for this case is not the train, as with the tension control, but the outlet cross section. The train is no longer kept constant but varies to maintain a cross-sectional setpoint. The train by speed correction can be realized on the train-controlled rolling stand VW or by varying the deflection.

For a closed control, the profile measuring device PMII behind the finishing block FB becomes necessary. The caliber filling behind this framework arrangement is used as a control variable for the cross-sectional control before the finished block. The inlet cross-section is varied by a variable train between the stands VW and HV so that behind the finished block FB optimal caliber filling and a constant width in cross-section and thus good ovality is achieved.

Reference numeral Directory

VW

vertical roller

HW

horizontal roll

DS

wire strand

concentration camp

Piston cylinder unit

SR

idler

KA

Load cell

WG

encoder

DR

Variable speed drive

DB

deflection

PMI

profiler

PMII

profiler

FB

finishing block

PY

pyrometer

KS

piston control

WR

rolling direction

AQR

Adaptive cross-section control

RE

Computing / control unit

PZM

Position measurement train

PZR

Position train control

PQR

Position cross-regulation

A ₁ , A ₂ , A ₀

cross-section

T ₀ , T ₁ , T ₂

temperature

h _R

deflection

F _S

tension

.DELTA.n

Speed correction

*

Indicator for setpoints

1

H scaffold

2

V framework

3

rolling

4

idler

5

Load cell

6

Control cylinder / cylinder

7

transducer

8th

Scissors and shredder

9

loop

10

Wire block (finished block)

11

Profile Measurement System

14

pyrometer

15

pyrometer

16

pyrometer

Claims (9)

1. A method for controlling the cross section of wire strands emerging from a wire mill train, in which the wire strand (DS) arriving from an intermediate train is fed to a finishing stand arrangement (FB) and a sizing stand arrangement optionally arranged downstream thereof, wherein the cross section of the wire strand is changed during the rolling process by exerting tension in a controlled fashion, and wherein tension is exerted in order to change the cross section no later than upstream of the last common driving group of the finishing stand arrangement (FB) or the sizing stand arrangement, respectively,
   characterized in
   that the tension exerted has such an intensity that the wire respectively emerges from the finishing stand arrangement (FB) or the sizing stand arrangement, preferably the finishing stand arrangement (FB), with a constant cross section.
2. The control method according to Claim 1,
   characterized in
   that tension is conventionally exerted upon the wire strand (DS) with a pair of speed-controllable horizontal and vertical stands (1, 2).
3. The control method according to Claim 1,
   characterized in
   that a nominal flection corresponding to a pre-calculated ratio between clamping force and tension force is produced in the wire strand (DS) with a tension roller (SR) pressed thereagainst by means of a displacement transducer (WG) and the reference value of the tension force being exerted upon the wire strand (DS) is adjusted by controlling the speed of adjacent roll stands.
4. The control method according to Claim 2,
   characterized in
   that the exerting of tension upon the wire strand (DS) takes place between individually controllable roll stand groups.
5. The control method according to Claim 4,
   characterized in
   that the exerting of tension upon the wire strand (DS) is pre-controlled by means of a temperature-dependent lateral flow correction.
6. The control method according to one of Claims 1 to 5,
   characterized in
   that the values of the cross section of the wire strand (DS) acquired downstream of the tension-controlled roll stands with the aid of profile measuring means are computationally processed and the entry cross section of the wire strand (DS) is changed before the entry into the last non-controlled forming stages by controlling the tension of the wire strand (DS) between tension-controlled roll stands and, if applicable, by means of the tension roller in order to achieve a constant cross section of the emerging wire strand (DS) measured downstream of the finishing stand arrangement (FB).
7. A wire mill train for carrying out the method according to Claims 1 to 6,
   characterized in
   that the roll stand arrangements consist of a sequence of roll stand groups that feature individually adjustable rolls (VW/HW) and/or individually drivable rolls (VW/HW) and are provided with means (PMI, PMII) for measuring the cross section of the wire strand (DS) which are connected to a tension control device.
8. The wire mill train according to Claim 7,
   characterized in
   profile measuring devices (PMI/PMII) that are arranged upstream and downstream of the tension-controlled roll stands, as well as downstream of the finishing stand arrangement (FB).
9. The wire mill train according to one of Claims 1 to 4,
   characterized in
   pyrometers (PYI/PYII) that are arranged upstream and downstream of the tension-controlled roll stands in order to measure the temperature of the wire strand (DS).

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