DE2264129A1 - DEVICE FOR MEASURING A REDUCTION OF AREA OF A WORKPIECE AND CONTROL DEVICE FOR A ROLLING MILL WITH SUCH A DEVICE - Google Patents

Description

1. Nippon Steel Corporation, Tokyo / Japan

2. Mitsubishi Ponki Kabushiki Kaisha, Tokyo / Japan

Vorr3.chturg ... for measuring a Flächenver rin ^ erimg a workpiece and SteuereInrtchtimp; for a rolling mill with such a device.

The invention relates to a device for moping a reduction in the area of a workpiece in a roll street, which includes: a V / alk, », orUöt., an electric lei tendes and in the V / alzüerüüi; govalzto.s Vv'oi'kstück, elekti'omagnetische Coils, polygamy associated with dam rolling rust and

- 2 ~ 3 0 9 8 2 8/0870

are changeable in their inductance in response to the workpiece passing through, as well as a device for determining a change in the inductance of the electromagnetic coils, and further to a control device for a rolling train such a device.

In the case of conventional rolls in a steel strip mill, a Measuring device for detecting the thickness can be used that a sheet material running through each roll stand of the rolling train can be aligned in its area reduction due to the particular thickness dimension detected by the measuring device. However v / iron metals such as tire steel have a complicated cross-section, so that the cross-sectional area and the profile so far only hard to pin down. To counter this difficulty, the use of an electromagnetic Proposed coil through which a rod-shaped metal is guided, as described in laid-open specification 2,020,749 is. According to the laid-open specification mentioned, a conductive body to be measured can be measured by an electromagnetic coil to change their inductance. This change in the inductance of the coil is a measure of the cross section of the conductive body. However, various problems were found in this measurement. For example, a change called the cross-sectional area of the conductive body shows only a slight change in the inductance of the measuring coil, while various factors have a disruptive effect on the measurement itself, for example a change in the cross-sectional profile of the conductive body that does not go through the center of the coil Arrangement of the conductive body, etc. Further, it was necessary to ensure the stability of a high frequency oscillator used therein increase considerably when attempting to measure the cross-sectional area of the conductive body directly. to Among other things, it was necessary to define the cross-sectional area dos conductive body into consideration.

Accordingly, it is the object of the present invention to provide an improved device for measuring the size of an area

309828/087 0 BAD ORIGINAL _ 5 ...

to create a reduction in an electrically conductive V / ERR piece to be rolled in a rolling train with high measuring accuracy, whereby a change in the cross-sectional area of the electrically conductive Material due to the rolling process in a rolling train is precisely determined, i.e. the difference or the ratio of cross-sectional areas of the workpiece is measured during, before and after the rolling process.

Another object of the invention is to provide an improved one Device for precisely measuring a change in area., i.e., the difference or a ratio of area reduction of a tire steel having a complicated sectional profile measured before and after the rolling process in a Walsstrasse.

Furthermore, the present invention is based on the object To create an improved measuring device which is based on the Working on the basis of a change in the inductance of an electromagnetic coil used to measure the reduction in area, neither a change in the cross-sectional profile of the workpiece, the arrangement of the same except "the center of the coil and the like have essentially no influence.

Another object of the invention is to provide an improved measuring device for the change in area of a in a rolling train rolled workpiece, with a measurement deviation due to the instability of a high-frequency oscillator, which is used to measure a change in the inductance of the associated electromagnetic coil, generated visual oscillation frequency is only slight. Finally, the present invention is based on the further object of a new and improved one To create a control device for controlling a rolling train for rolling a workpiece with a complicated cross-sectional profile, wherein the control device works very precisely and on the basis of a fourth of the reduction in area of the workpiece which is carried out by the aforementioned Meßvorriehturig is given.

The object according to the invention is achieved with a device of the

309828/0870 _ 4 -

gangs' described type solved in that the electromagnetic Coils in pairs on the supply and discharge side the roll stands are arranged coaxially to the direction of movement of the workpiece and that a device for measuring a reduction in the area of the workpiece based on the changes the inductance of the electromagnetic coils provided fet.

The device for measuring a change in area can preferably comprise a pinhole frequency oscillator with each of the electromagnetic coils, the oscillation frequency of which changes in response to the DuI ^-1 ChIaUf of the workpiece through the associated coil, while a device for generating a difference or a ratio between the changes in the oscillation frequencies it is provided to give a measure of a difference or a ratio between the cross-sectional areas of the workpiece in the plane of the electromagnetic coils.

The invention will now be described and explained in more detail below with reference to the accompanying drawings. It shows

Fig. 1 is a schematic representation of the basic principle of a Apparatus for measuring a cross-sectional area of an electrically conductive body for use therewith Invention;

2 shows a schematic representation of a device for measuring the difference between the thickness of a workpiece rolled in a roll stand before and after the rolling process according to the invention, and using a superposition method;

3 shows a schematic representation of a device for measuring a relationship between the thickness of a workpiece rolled in a roll stand before and after the rolling process according to the invention _. , d using an impedance bridge;

309828/0870

Pig. .4 a view similar to Pip; 5 * but with the illustration another Ausüihrungsbeißpiels of the invention below Application of a superposition process and

5 shows a schematic representation of a control device for controlling a steel strip mill using the arrangement shown in FIG.

With reference to FIG. 1, the basic principles of a device used here for measuring a cross-sectional area of a body made of electrically conductive material will now be explained in more detail to explain the invention. The arrangement shown comprises an electromagnetic coil 10, a body made of electrically conductive material 12, which is passed through the coil 10 without actually touching it. A high-frequency oscillator 14 cooperates with the coil 10 in such a way that a high-frequency magnetic field with a frequency f is built up around the coil 10. For purposes of clarity, it is now assumed that the electrically Ie itenden body 12 have no magnetic properties and electrical conductivity of approx. If the body 10 is made of magnetic material, it can be brought to a temperature above its Curie temperature so that it is not magnetic. Due to its skin effect, the high-frequency magnetic field can penetrate into the conductive body 12 to a depth ο (cf. FIG. 1), which is expressed by the following equation

where: cO = angular frequency of the high-frequency magnetic field

equal to its frequency £ multiplied by

II = permeability of the material of the body 12

under the assumed assumption, equal to 4 T. 10 "'Henry / Mo ter.

- 6 309828/0870

From the above equation it is clear that the depth of penetration

ö is negligible, if the frequency f_ enough greatly increased. This means that the high-frequency radiation field in the conductive body 10 can essentially be completely disregarded because of the skin effect if the frequency f_ is increased sufficiently. Under these circumstances, the coil 10 changes its equivalent inductance. It is assumed that the penetration depth ο is negligibly small, so that the change in inductance corresponds to the following relation:

Δ L = A

to <

Lo \ Sun /

where : Lo = inductance of the coil 10, through which

no conductive body extends.

L = change in inductance of the coil 10 because of the

through these extending conductive bodies,

So = cross-sectional area of the coil 10,

S., = cross-sectional area of the conductive body 12,

A = constant determined by the shape of the coil

<> i = another constant, determined by the shape of the coil 10.

It can be seen from this that a change in the inductance of the coil 10 can be measured, as a result of which the cross-sectional area of the conductive body 12 in the plane of the coil 10 is determined .

While extending through the coil 10, conducting body 12 as described non-magnetic material consisting we do, 'it may be made of magnetic material, as far as its permeability remains substantially unchanged compared with a comparison used for calibration body.

309828/087 0

2264179

More detailed information can be found in German Offenlegungsschrift 2 020 which has already been mentioned above. Farther are flow meters in which the arrangement from Fig. 1 is used, in the German Auslegeschrift 2 03.6 567 described and claimed.

The arrangement shown in FIG. 1 can have a cross-sectional area effectively determine any electrically conductive body, even if it has a complicated cross-sectional profile. However, the use of such an arrangement for determining the cross-sectional area of electrically conductive bodies posed various problems. For example, a change called the cross-sectional area of the conductive body shows only a very small change in the impedance of the coil. Furthermore, a Changing the cross-sectional profile of the conductive body, placing it off the center of the coil, and the like influence the change in the impedance of the coil. In order to measure the cross-sectional area directly, it is also necessary to to considerably increase the stability of a high-frequency oscillator used and also the cross-sectional profile of the to take into account the measuring electrically conductive body.

According to the present invention, these problems are solved in an efficient and simple manner. According to the basic ideas of the invention is a couple electromagnetic measuring coils each on the supply and discharge side a roll stand of a steel strip rolling mill, and a workpiece to be rolled is located in such Able to run through both coils. The arrangement from Flg. 1, to determine the size of a reduction in area dec workpiece is used in the roll stand, more precisely for determination a difference or ratio between cross-sectional areas the same before and after passing through the roll stand. Thus, according to the invention, it does not directly become an absolute Fourth of the cross-sectional area of the workpiece measured,

Fig. 2 shows an embodiment eier invention, at. which one

309828/0870 -8-

a difference between a cross-sectional area of a workpiece before the rolling process and after the rolling process under Application of an overlay process is appreciated. the The arrangement shown comprises a roll stand, which is represented by a pair of work rolls 16, and a pair of electromagnetic measuring coils 10 and 18, which are coaxial on the feed and exit side of the. Roll stand 16 are arranged. One to The rolling workpiece 12 initially runs through the bobbin 10 the feed side of the rolling stand 16 and then between the work rolls 16 through, between v / elchen the workpiece is reduced in its thickness to the desired hatred. Afterward If the rolled workpiece 12 runs through the coil 1_8 on the discharge side of the roll stand 16.

The coil 10 forms part of a high-frequency oscillator 20 which normally generates a predetermined unchanged frequency f. In the same way, the coil 18 forms part of another high-frequency oscillator 22 which normally generates _{a predetermined unchanged frequency f o.} The workpiece 12 enters the Skips ¹ 10 a, thereby deren- inductance changed so v; ith that the oscillation frequency of the oscillator 20 is f f of its value to a value. + Λ f,, changed.

—Ο ~ -ol —1

If the workpiece 12 enters the coil 18, the oscillator 22 is changed in the same way from a frequency £ ρ to a frequency + Δ £ _2 .

The high frequency of f, + A i \ of the oscillator 20, as well as the

-Oi -J.

Frequency f ₂ + Λ £ o "es oscillator 22, is applied to a superimposing converting transmitter 2) \ . The superimposing converting transmitter 24 comprises a pair of oscillators for generating (3 frequencies f or fp, a superimposing device for generating a difference frequency between the frequencies Ht ⁺ A ii ^{un <} ^ f ι * ie a frequency of / if. and for generating a difference frequency · - .; tS f _o between the frequencies £ _o + A f _o and f _, ^, Sü'iie a ν . · ^{τ 'ν ί} terc Ü]) cr]; - ~ g rungsoinri.chtung for generating a differentiator -enzfro- .: ucji:...'. ^ f_, - _c \ f _o superimposed from the

309828/0870 - 9 -

Frequencies A ί \ + f _o * even if these components are not shown. The difference frequency / 4 £ n - ^ £. ₂ ^{V7 is passed to a} frequency approximation converter 26, by which it is converted into a corresponding voltage.

The ratio between the surface area of the workpiece 12 in the plane of the coil .10 on the feed side of the roll stand 16 and the oscillation frequency coming from the oscillator 20 can be expressed by the following equation:

⁸ Ml = B ₁

^S ol ^f ol

where B-, is a constant. The same applies to the Coil l8 on the discharge side of the roll stand 16 the following equation:

^S M2 = B ₂ 4 ^f ?

⁸ o2 ^f o2

where B ₂ eim is a constant. The difference frequency Αί \ -Α.χ_ ₂ j which is formed by the superimposed converting transformer 2h is expressed by the following equation:

AT ₁ - Λ ί ₂ - ^f ol ^f ol
^B i ~ " _ ^ M1_
⁸ Ol ^f oP
_ _ ! ■ 'Ϊ2 - ^B a κ (s _M1 - ^S M2 ^ ^S o2 v / ob ei K i ^f o2 χ ⁸ Ol B ₂

It is now on the Haiui. That f ,, i ' _n -, ß ι and 3 _{o can be} so vci-bo-tuned that they correspond to the equation;

309828/0870

f 1 f

¹ Ol = O2

^B l ^S ol ^B 2 ^S o2

For this reason, the frequency converter is 26 output voltage proportional to the difference in savings (^ f-, -Δ f) and represents a measure of the difference in the Quorschnitfcö ·· - area of the workpiece 12 before and after the VJaI ζ process.

The arrangement from Fig. 2 forms a difference between the vibration frequencies before and after the workpiece is rolled, which is why the area reduction of the workpiece with very little Deviations based on the aforementioned factors can be determined.

In the arrangement of FIG. 2, each oscillator has a frequency change rate from Af / f on, which is very low and

- "3 -4

is between 10 ^ and 10. If one now wants to try to obtain an absolute value for a cross-sectional area of a workpiece, the measuring devices used must be stabilized to a high degree, which is very difficult in an environment such as a rolling mill. In this environment, a device as shown in Fig. 3 can be effectively used to minimize the effects of a change in a high oscillation frequency applied to the associated electromagnetic coil, as well as the effects of a change in after the measuring operation applied voltage.

The arrangement shown in Fig. ¹ \ comprises a pair of electromagnetic coils 10 and 18, which with respect to a rolling mill · stand 16 in the same manner as that in connection with; Flg... The other left of the two coils 10 and; iS are grounded, while a tap on the Rogeüvvlder ::. 1 ·· υ.ι · ι *. '·'!

■ - 11

309828/08 7 0

BATH ORIGINAL

at one end of a balance detector 30 is connected, which in turn is grounded at the other end. The coils 10 and 18 with the variable resistor 28 thus form an impedance bridge which is fed by a high-frequency source 32 which is connected across the variable resistor 28. The frequency of the source 32 can be predetermined in accordance with the cross-sectional area of the respective workpiece to be rolled. It has been found that the frequency of the source 32 is between 100 kHz and 5 megahertz with a satisfactory result.

The arrangement of Fig. 3, the relationship between one Cross-sectional areas of the workpiece in the plane of the coil 10 and the cross-sectional area in the plane of the coil 18 from one The relationship between the two parts is determined, - in which the total resistance of the variable resistor 28 is divided by the tap on this when the impedance bridge is in a balanced state is located.

Fig. 4 shows a further embodiment of the present invention, in which a ratio of the cross-sectional area of a workpiece to be rolled is determined by a superposition method. A pair of oscillators 20 and 22 are provided which are identical to those from FIG. 2, only with the exception that in the absence of a workpiece in the associated coils 10 and 18, a common frequency T ^ is generated. A reference frequency generator 34 outputs a reference frequency to a pair of superimposed converting transmitters 24 'and 24 "which is equal to the common frequency f, the frequencies coming from the oscillators 20 and 20, respectively, being applied to the superimposed converting transmitters 24' and 24" will.

In the arrangement of Fig. 4, the workpiece 12 passes through the coil 10, whereby a change in the oscillation frequency by one Value A f, is effected in the associated oscillator 20, v / obei the Value “Δ f, in turn from the superimposed converting transformer 24 '. is detected. In the same way, it causes running through rolled workpiece 12 through the coil 18 a Fr · -: .mei · - :: -

309828/0870 " ¹²

Change Δ ί " _{2 of} the associated oscillator 22. This frequency change is detected by the superimposed converting transmitter 24". Then these frequency changes detected by the superimposed converting transmitters 24 'and 24 "are fed to a divider J> 6 ", in which the ratio A f ₂ / A ί _{χ is} formed. Since the relationship Af ₂ / ^ f ₁ = k S _M2 / S _M1 , where k is a constant, the output signal of the dividing device 36 is a measure of the ratio of the cross-sectional area of the workpiece on the supply side to the cross-sectional area of the workpiece on the discharge side Roll stand 16 is.

Referring now to Fig. 5, a controller for use in a continuous strip mill is shown, which both the rolling speed as well as controlling the area reduction of the sheet metal strip on each roll stand using the arrangement of Fig. 4, In Fig. 5 the steel strip mill is under the general reference number 50 and includes a plurality of roll stands which are arranged one behind the other, of which, however, only three are shown and labeled "FRAMEWORK i", "FRAMEWORK II" and "FRAMEWORK III" are designated. Each of these roll stands comprises a pair of work rolls 16 in which the surface passes through one after the other various rolling stands running workpiece 12 is reduced in a desired V / iron, as well as a mechanism 52 for detecting the setting position on the work rolls 16 and for controlling the same, and a mechanism 54 for detecting the rolling speed the work rolls 17 and for controlling the same.

For the purpose of a simplified illustration, the detectors and control devices are not shown. Furthermore, an arrangement from FIG. 4 is effectively assigned to each of the roll stands, a single reference frequency generator being connected to all of the superimposed converting transmitters 24 'and 2V. All mechanisms 52 for detecting the contact position, mechanisms ^c j ^! i aim detection of the rolling speed and

309828/0870

Divider devices J6 are connected to a programmed digital control computer 56.

A workpiece 12 is successively and alternately passed through the coils and roll stands, while the control computer 56 receives the respective data for each of the roll stands l6, which are output by the associated mechanism 52, the mechanism 54 and the dividing device ~ $ 6 for controlling the VJaI ζ process This proceeds according to the law that a mass flow for the workpiece 12 is kept constant through the entire rolling train 50. More specifically, it is assumed that on each roll stand S, and S "p represent the cross-sectional areas of the workpiece on the feeding and discharging side, respectively, so that V, and Vp show the feeding and discharging speeds of the same, where the rolling process should be controlled so that it corresponds to the following equation:

^S M1 ^V 1 ^{= S} M2 ^V 2

Palis the dividing device effectively connected to a roll stand 36 finds that the cross-sectional area is at the Feed side from a value S ^, for some reason to one Value S 'has changed, the arithmetic unit 56 controls the supplied

Hi
arranged mechanism 52 for the angle of attack and / or the mechanism 5 ^ for the rolling speed so that the rotational speed or the cross-section on the rolling stand corresponds to one of the following two equations:

ν = - V

2. _q ^V l

^fa M2

or V ₁

^D M2 * ^D M1
2

where V, and V _{0 are released} by the associated mechanism 5 ^ for the rolling motion and are therefore known. In this way

309828/0870 -U-

will "the workpiece in a stable and continuous manner in the successive roll stands rolled.

The control device has been described and illustrated in connection with the device from FIG. 4, but it is obvious that the control device can also be effectively connected to any other measuring device for the reduction in area, for example with the device from FIG. 2 and J.

In summary, the present invention relates to a device in which two measuring coils on the feed and discharge side a roll stand are arranged, an electrically conductive workpiece runs through polygons. An oscillator, v / elcher one of the coils., speaks to the passage of the workpiece by the associated coil in such a way that its oscillation frequency is changed. A difference between frequency changes both oscillators, or a ratio between them, is measured, so that one can give a measure of a difference or ratio between the cross-sectional areas of the workpiece in the planes of both coils. This also refers to the following Patent applications referenced: German Offenlegungsschrift 2,020,749 (US application 32,551) and German Offenlegungsschrift 2,016,567 (U.S. Application 25,668).

Even if the present invention is described and illustrated in more detail in connection with some preferred exemplary embodiments it is obvious that numerous changes and modifications are possible without departing from the scope of the invention to deviate.

309828/0870

Claims (1)

Claims e (1.) Device for measuring a reduction in area of a square piece in a rolling train, which comprises a rolling stand, an electrically conductive workpiece rolled in the roll stand, electromagnetic coils connected to the roll stand and are changeable in their inductance in response to the workpiece being passed, as well as a device for plaguing a change in the inductance of the electromagnetic coils, characterized in that the electromagnetic Coils (10, 18) in pairs on the feed and discharge side of the roll stands (16) coaxially to the direction of movement of the workpiece (12) are arranged, and that a device for measuring a reduction in area of the workpiece (12) on the basis of the changes the inductance of the electromagnetic coils (10,18) is provided. 2. Apparatus according to claim 1, characterized in that the device for measuring the Flädienvaringe a warning ~ (24) indicating a difference between cross-sectional areas of the workpiece (12) in the plane of the electromagnetic coils (10, 18). 5. Apparatus according to claim 1, characterized in that the device for measuring the reduction in area a device (10, 18, 2.8, JO, JS; 24 ', 24 ", ^ 4, for determining a relationship between cross-sectional areas of the workpiece (12) in the plane of the electromagnetic coils (10, 18). h . Device according to claim 1, 2 or 5 > characterized in that a first oscillator (20) with one of the electronic coils (10) is provided, the flow rate of which corresponds to the inductance of an electromagnetic coil ( 10) changes that a second oscillator (22) is provided with the other electromagnetic Spj Ic5 (Vo) , 309828/0870 If ₁ whose oscillation frequency is related to the inductance of the assigned Coil (l8) changes, as well as a device (24,26) for determining a reduction in the area of the workpiece (12) through the V / alzgerüst (l6) due to changes in inductance both electromagnetic coils (10, 18). 5. The device according to claim 4, characterized in that the device for determining the area reduction a superimposed converting transmitter (24) with a pair of normally equal oscillation frequencies as the first or second oscillator (20 or 22) having oscillators, and only two superimposing devices for generating differences in oscillation frequency between the first and second oscillators (20, 22) and the associated ones Oscillators and then for generating a frequency difference between the Differcnzfrequenzen, and also a frequency voltage converter (26) for converting the frequency difference into a corresponding voltage, which is used as a measure of a difference between the cross-sectional areas of the workpiece (12) in the planes of the electromagnetic coils (10, 18) is provided is. 6. Apparatus according to claim 4, characterized in that the first oscillator (20) has the same oscillation frequency as the second oscillator (22), and that the device for determining the area reduction has a reference frequency generator (34) same oscillation frequency v / ie the first and the second oscillator (20, 22) on we lsi that a first superimposed converting transmitter (24 ') for generating a difference in the oscillation frequency between the first oscillator (20) and the reference frequency generator (3> 4 ) is provided, as well as a second superimposed converting transmitter (24 ") for generating a difference in the oscillation frequency between the first oscillator (22) and the reference frequency generator (3> 4), that also a dividing device (36) - 17 309828/0870 is provided for generating a ratio between the difference frequencies, which of the first and the second superimposed converting transmitter (24 ', 24 ") are generated, which is a measure of the ratio of cross-sectional areas of the workpiece (12) in the planes of the electromagnetic coils (10, 18). 7. Control device for a rolling train, with at least one roll stand with a pair of work rolls for reducing the surface of an electrically conductive workpiece, a mechanism for Detection of the contact position of the workpiece, so that a corresponding output is provided and the contact position is controlled A mechanism for detecting the rolling speed of the work rolls so that an appropriate output is provided and the rolling speed is controlled, and with one of the output of the rolling speed detecting mechanism responsive control device for controlling at least one of the mechanisms for detecting the setting position or the rolling speed, so that there is a uniform mass flow for the workpiece, and with a device according to one of the preceding Claims, characterized in that the control device (56) responds to a measure for the area reduction of the workpiece (12) so that at least the Mechanism (52) for detecting the setting position or the mechanism (54) for detecting the rolling speed can be controlled. 8. Control device according to claim 'J ₃ in particular with a device according to claim 6, characterized in that the control device (56) is responsive to the ratio between cross-sectional areas of the workpiece (12), which of the dividing device (36) of the measuring device for controlling at least the Mechanism (52) for detecting the starting position or the mechanism (54) for detecting the rolling speed is released. 309828/0870 Jt Blank page