EP0272204B1 - Method for controlling the thickness of tubewall - Google Patents
Method for controlling the thickness of tubewall Download PDFInfo
- Publication number
- EP0272204B1 EP0272204B1 EP87730165A EP87730165A EP0272204B1 EP 0272204 B1 EP0272204 B1 EP 0272204B1 EP 87730165 A EP87730165 A EP 87730165A EP 87730165 A EP87730165 A EP 87730165A EP 0272204 B1 EP0272204 B1 EP 0272204B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- wall thickness
- pipe
- measured
- values
- rolling mill
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
- B21B17/14—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling without mandrel, e.g. stretch-reducing mills
Definitions
- the invention relates to a method for controlling the tube wall thickness in a multi-stand continuous stretch-reducing rolling mill with devices for measuring the tube wall thickness before the forming and the inlet speed of the pipe, a computer unit for measured value processing and a device for speed control of the drive motors of the rolling mill.
- the stretching of the rolling stock and thus its wall thickness is specifically influenced by the setting of the ratios of the roll speeds from stand to stand.
- the wall thickness of the pipes entering the rolling mill there are also wall thickness differences in the formed pipes if the speed ratios are unchanged during the forming.
- suitable devices for speed control by varying the wall thickness of the incoming tube and correspondingly adjusting and changing the roller speed ratios, it is possible to compensate to a certain extent for different wall thicknesses both from tube to tube and within a tube.
- Such a device and a method according to the preamble of claim 1 is known, for example, from Sloma, J., Automatic control of the tube wall thickness on a multi-stand stretch-reducing mill, from "Problems of Project Planning", 1973, No. 8, pages 352-356. It is used to measure the wall thickness of the pipe entering the rolling mill, depending on the length, from this the target stretches and target speed ratios are determined and a corresponding speed change is carried out at the point in time at which the cross-sections of the rolling stock assigned to the measurement data are in the area of the rolling mill intended to influence the wall thickness.
- This control device makes it possible to compensate for small wall thickness differences over pipe length sections, which roughly correspond in volume to the sections of the rolling stock located simultaneously in the area of influence of the rolling mill. If, however, larger wall thickness differences occur at shorter intervals, the control device mentioned inevitably reforms individual pipe sections with an excessive elongation and, as a result, impermissibly high wall thickness reductions occur with regard to the finished pipe tolerances. This is due to the fact that the speeds cannot be pressed continuously.
- the invention has for its object to compensate for changing tube wall thicknesses in short lengths of rolling stock, in such a way that each rolling stock cross-section is reshaped with maximum, but not greater than the stretching or wall thickness reduction necessary to achieve a desired finished tube wall thickness.
- the control law is influenced in accordance with the deviation between the setpoint value of the finished pipe wall thickness and the minimum value of the wall thickness values, which are measured after the forming, and are each to be assigned to a pipe length section which has the same volume as the section of the rolling stock located in the wall thickness influence area of the rolling mill is.
- control law for determining the drive speeds from the measured values of the wall thicknesses of the pipe before the forming is corrected independently of the pilot control or by means of a control circuit.
- Such an adaptation can be carried out within a tube as well as from tube to tube.
Description
Die Erfindung betrifft ein Verfahren zur Steuerung der Rohrwanddicke in einer vielgerüstigen kontinuierlichen Streckreduzierwalzstraße mit Einrichtungen zur Messung der Rohrwanddicke vor der Umformung sowie der Einlaufgeschwindigkeit des Rohres, einer Rechnereinheit zur Meßwertverarbeitung und einer Einrichtung zur Drehzahlsteuerung der Antriebsmotoren der Walzstraße.The invention relates to a method for controlling the tube wall thickness in a multi-stand continuous stretch-reducing rolling mill with devices for measuring the tube wall thickness before the forming and the inlet speed of the pipe, a computer unit for measured value processing and a device for speed control of the drive motors of the rolling mill.
In einer Rohrstreckreduzierwalzstraße wird die Streckung des Walzgutes und damit seine Wanddicke durch die Einstellung der Verhältnisse der Walzendrehzahlen von Gerüst zu Gerüst gezielt beeinflußt. Bei unterschiedlichen Wanddicken der in die Walzstraße eintretenden Rohre ergeben sich ebenfalls Wanddickenunterschiede bei den umgeformten Rohren, wenn die Drehzahlverhältnisse während der Umformung unverändert sind. Mit Hilfe geeigneter Vorrichtungen zur Drehzahlsteuerung kann durch Messung der Wanddicke des eintretenden Rohres und entsprechende Einstellung und Veränderung der Walzendrehzahlverhältnisse in gewissem Umfang ein Ausgleich unterschiedlicher Wanddicken sowohl von Rohr zu Rohr als auch innerhalb eines Rohres erreicht werden. Eine solche Vorrichtung und ein Verfahren, entsprechend dem Oberbegriff des Anspruchs 1 ist z.B. aus Sloma, J., Automatische Regelung der Rohrwanddicke auf einem vielgerüstigen Streckreduzierwalzwerk, aus "Probleme der Projektierung", 1973, Nr. 8, Seiten 352-356 bekannt. Mit ihr wird die Wanddicke des in die Walzstraße eintretenden Rohres längenabhängig gemessen, hieraus Sollstreckungen und Solldrehzahlverhältnisse ermittelt und eine entsprechende Drehzahländerung zu dem Zeitpunkt durchgeführt, zu dem die den Meßdaten jeweils zugeordneten Querschnitte des Walzgutes sich in dem zur Wanddickenbeeinflussung vorgesehenen Bereich der Walzstraße befinden. Mit dieser Steuerungsvorrichtung ist es möglich geringe Wanddickenunterschiede über Rohrlängenabschnitte auszugleichen, die in etwa volumenmäßig dem jeweils gleichzeitig im Einflußbereich der Walzstraße befindlichen Walzgutabschnitten entsprechen. Treten jedoch größere Wanddickenunterschiede in kürzeren Abständen auf, so werden mit der genannten Steuerungsvorrichtung zwangsläufig einzelne Rohrabschnitte mit einer zu großen Streckung umgeformt und infolge dessen treten hinsichtlich der Fertigrohrtoleranzen unzulässig hohe Wanddickenreduktionen auf. Dies ist darauf zurückzuführen, daß keine fortlaufende Anpressung der Drehzahlen möglich ist.In a pipe stretch reducing rolling mill, the stretching of the rolling stock and thus its wall thickness is specifically influenced by the setting of the ratios of the roll speeds from stand to stand. With different wall thicknesses of the pipes entering the rolling mill, there are also wall thickness differences in the formed pipes if the speed ratios are unchanged during the forming. With the help of suitable devices for speed control, by varying the wall thickness of the incoming tube and correspondingly adjusting and changing the roller speed ratios, it is possible to compensate to a certain extent for different wall thicknesses both from tube to tube and within a tube. Such a device and a method according to the preamble of claim 1 is known, for example, from Sloma, J., Automatic control of the tube wall thickness on a multi-stand stretch-reducing mill, from "Problems of Project Planning", 1973, No. 8, pages 352-356. It is used to measure the wall thickness of the pipe entering the rolling mill, depending on the length, from this the target stretches and target speed ratios are determined and a corresponding speed change is carried out at the point in time at which the cross-sections of the rolling stock assigned to the measurement data are in the area of the rolling mill intended to influence the wall thickness. With This control device makes it possible to compensate for small wall thickness differences over pipe length sections, which roughly correspond in volume to the sections of the rolling stock located simultaneously in the area of influence of the rolling mill. If, however, larger wall thickness differences occur at shorter intervals, the control device mentioned inevitably reforms individual pipe sections with an excessive elongation and, as a result, impermissibly high wall thickness reductions occur with regard to the finished pipe tolerances. This is due to the fact that the speeds cannot be pressed continuously.
Der Erfindung liegt die Aufgabe zugrunde, einen Ausgleich von sich in kurzen Walzgutlängenabschnitten ändernden Rohrwanddicken durchzuführen, und zwar so, daß jeder Walzgutquerschnitt mit maximaler, aber nicht mit größerer als der zur Erzielung einer gewünschten Fertigrohrwanddicke notwendigen Streckung bzw. Wanddickenreduktion umgeformt wird.The invention has for its object to compensate for changing tube wall thicknesses in short lengths of rolling stock, in such a way that each rolling stock cross-section is reshaped with maximum, but not greater than the stretching or wall thickness reduction necessary to achieve a desired finished tube wall thickness.
Diese Aufgabe wird erfindungsgemäß durch die Merkmale des Oberbegriffs des Anspruchs 1 gelöst, wobei eine Datenglättung der gemessenen Werte erfolgt z.B. durch Mittelwertbildung und daß die Verhältnisse der Walzendrehzahlen von Walzgerüst zu Walzgerüst fortlaufend nach einem Steuerungsgesetz in Abhängigkeit von diesem geglätteten Wert und bezogen auf den sich jeweils im Einflußbereich der Walzstraße befindlichen gemessenen Rohrbereich mit der kleinsten, für die gewünschte Fertigrohrwanddicke erforderlichen Streckung eingestellt werden.
Als Steuerungsgesetz kommmt beispielsweise die Wanddickenänderung zur Änderung der Drehzahlverhältnisse in Frage.
Es wird also bei diesem Verfahren fortlaufend festgestellt, welche Meßstellen mit den zugehörigen gespeicherten Daten sich augenblicklich in dem Bereich der Walzstraße befinden, der für die Wanddickenbeeinflussung vorgesehen ist. Die den Meßstellen zugeordneten Wanddickenmeßdaten werden verglichen und der jeweils kleinste Meßwert zur Steuerung der Antriebsmotoren herangezogen. Statt der Wanddickenwerte können auch hieraus abgeleitete Streckgradsollwerte oder Differenzen zwischen diesen beiden Größen und vorgegebenen Sollwerten verwendet werden.This object is achieved according to the features of the preamble of claim 1, data smoothing of the measured values taking place, for example, by averaging and that the ratios of the roll speeds from roll stand to roll stand continuously according to a control law as a function of this smoothed value and based on the respective value measured tube area located in the area of influence of the rolling mill with the smallest extension required for the desired finished tube wall thickness.
As a control law, for example, the change in wall thickness to change the speed ratios comes into question.
This method continuously determines which one Measuring points with the associated stored data are currently in the area of the rolling mill which is intended for influencing the wall thickness. The wall thickness measurement data assigned to the measurement points are compared and the smallest measurement value is used to control the drive motors. Instead of the wall thickness values, stretching target values derived therefrom or differences between these two quantities and predetermined target values can be used.
Bei systematischem Verlauf der Wanddicke über der Rohrlänge, wie er häufig abhängig vom Rohrherstellungsverfahren auftritt, ist es nach einem weiteren Merkmal der Erfindung vorteilhaft, die vor der Umformung gemessenen Wanddickenwerte durch für bestimmte Längenabschnitte gemeinsam gültige mathematische Funktionen anzunähern. Auf diese Weise wird durch statistische Auswertung der Wanddickenverläufe von mehreren unter gleichen oder ähnlichen Umformbedingungen in den der Streckreduzierwalzwerke vorgeschaltenen Umformanlagen erzeugten Rohren eine größere Sicherheit bei der Glättung der Meßdaten und der Ermittlung der Sollwertvorgabedaten erreicht.In the case of a systematic course of the wall thickness over the pipe length, as often occurs depending on the pipe production process, it is advantageous according to a further feature of the invention to approximate the wall thickness values measured before the forming by mathematical functions that are common to certain sections of length. In this way, greater statistical reliability in smoothing the measurement data and determining the setpoint data is achieved by statistically evaluating the wall thickness curves of a plurality of pipes produced under the same or similar forming conditions in the forming plants upstream of the stretch-reducing roll mills.
Nach einer Ausgestaltung der Erfindung ist vorgesehen, daß das Steuerungsgesetz beeinflußt wird gemäß der Abweichung zwischen dem Sollwert der Fertigrohrwanddicke und dem Minimalwert der Wanddickenwerte, die nach der Umformung gemessen werden und jeweils einem Rohrlängenabschnitt zuzuordnen sind, der dem sich im Wanddickeneinflußbereich der Walzstraße befindlichen Walzgutabschnitt volumengleich ist. Somit wird eine Kontrolle und Adaption der Drehzahlsteuerung ermöglicht, wenn die Wanddicke des Rohres nach der Umformung fortlaufend gemessen und aus diesen Meßwerten jeweils für Rohrlängenabschnitte, die unter Berücksichtigung der durchgeführten Streckung der Einflußlänge entsprechen, die Minimalwerte der Wanddickenmeßdaten ermittelt werden. Bei einer Abweichung dieser Werte von der Sollwanddicke des Fertigrohres wird das Steuerungsgesetz zur Ermittlung der Antriebsdrehzahlen aus den Meßwerten der Wanddicken des Rohres vor der Umformung unabhängig von der Vorsteuerung oder mittels Regelkreis korrigiert. Eine solche Adaption kann innerhalb eines Rohres als auch von Rohr zu Rohr durchgeführt werden.According to one embodiment of the invention, it is provided that the control law is influenced in accordance with the deviation between the setpoint value of the finished pipe wall thickness and the minimum value of the wall thickness values, which are measured after the forming, and are each to be assigned to a pipe length section which has the same volume as the section of the rolling stock located in the wall thickness influence area of the rolling mill is. This enables control and adaptation of the speed control if the wall thickness of the pipe is continuously measured after forming and from these measured values for pipe length sections, which correspond to the length of influence taking into account the stretching carried out, the minimum values of the wall thickness measurement data are determined. If these values deviate from the target wall thickness of the finished pipe, the control law for determining the drive speeds from the measured values of the wall thicknesses of the pipe before the forming is corrected independently of the pilot control or by means of a control circuit. Such an adaptation can be carried out within a tube as well as from tube to tube.
Claims (3)
- A method for controlling the pipe wall thickness in a multiple-stand continuous stretch-reducing rolling mill with means for measuring the wall thickness of the pipe, a computer unit for processing the measured values and a means for controlling the speed of rotation of the drive motors, the wall thickness of the pipe being measured continuously before it enters the rolling mill and furthermore the passage movement of the measuring points associated with the measured values being determined by means of measurement of speed,
characterised in that smoothing of the data of the measured values takes place, for instance by taking the mean of adjacent values, and that the ratios of the roller speeds from roller stand to roller stand are continually adjusted with the minimum extension required for the desired finished pipe wall thickness according to a control law dependent on this smoothed value and relative to the measured pipe region located in each case in the sphere of influence of the rolling mill. - A method according to Claim 1, characterised in that the wall thickness values measured before shaping are approximated by mathematical functions which are jointly valid for certain length sections.
- A method according to Claim 1 or 2, with a means for measuring the pipe wall thickness after shaping, characterised in that the control law is influenced in accordance with the deviation between the desired value of the finished pipe wall thickness and the minimum value of the wall thickness values which are measured after shaping and are each associated with one pipe length section which is of equal volume to the rolled stock section located in the sphere of influence of wall thickness of the rolling mill.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863643659 DE3643659A1 (en) | 1986-12-18 | 1986-12-18 | METHOD FOR CONTROLLING THE PIPE WALL THICKNESS |
| DE3643659 | 1986-12-18 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0272204A2 EP0272204A2 (en) | 1988-06-22 |
| EP0272204A3 EP0272204A3 (en) | 1988-11-09 |
| EP0272204B1 true EP0272204B1 (en) | 1992-07-15 |
Family
ID=6316703
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87730165A Expired - Lifetime EP0272204B1 (en) | 1986-12-18 | 1987-12-15 | Method for controlling the thickness of tubewall |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0272204B1 (en) |
| DE (2) | DE3643659A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10201717C1 (en) * | 2002-01-18 | 2003-04-10 | Sms Meer Gmbh | Pipe rolling stand in which at least two rollers work together, takes the measured pipe wall thickness at different peripheral positions to control the roller rotary speeds independently |
| DE102017211481A1 (en) | 2017-07-05 | 2019-01-10 | Sms Group Gmbh | Device for controlling a draft-reducing mill |
| DE102017220750A1 (en) | 2017-11-21 | 2019-05-23 | Sms Group Gmbh | Device for controlling a draft-reducing mill |
| DE102018217378B3 (en) | 2018-10-11 | 2020-03-26 | Sms Group Gmbh | Wall thickness control when reducing pipe stretch |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1427922C3 (en) * | 1965-04-07 | 1975-08-14 | Fa. Friedrich Kocks, 4000 Duesseldorf | Adjustment device for regulating the total degree of stretching when reducing the stretching of pipes |
| GB1158754A (en) * | 1967-03-21 | 1969-07-16 | Kocks Wermelskirchen Gmbh | Process for Stretch-Reducing Tubes |
| US3496745A (en) * | 1967-05-01 | 1970-02-24 | Kocks Gmbh Friedrich | Process for stretch-reducing tubes |
| US3564882A (en) * | 1968-04-22 | 1971-02-23 | Allegheny Ludlum Steel | Rolling mill control system |
| DE2947233C2 (en) * | 1979-11-23 | 1992-03-12 | Kocks Technik Gmbh & Co, 4010 Hilden | Device for controlling the wall thickness of pipes |
| JPS60199514A (en) * | 1984-03-22 | 1985-10-09 | Sumitomo Metal Ind Ltd | Draw rolling method of pipe |
-
1986
- 1986-12-18 DE DE19863643659 patent/DE3643659A1/en active Granted
-
1987
- 1987-12-15 DE DE8787730165T patent/DE3780429D1/en not_active Expired - Lifetime
- 1987-12-15 EP EP87730165A patent/EP0272204B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0272204A3 (en) | 1988-11-09 |
| DE3643659A1 (en) | 1988-07-07 |
| EP0272204A2 (en) | 1988-06-22 |
| DE3780429D1 (en) | 1992-08-20 |
| DE3643659C2 (en) | 1990-05-17 |
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