GB2066473A

GB2066473A - Apparatus for measuring the gap between a pair of working rolls

Info

Publication number: GB2066473A
Application number: GB8039876A
Authority: GB
Original assignee: Vereinigte Flugtechnische Werke GmbH; Vereinigte Flugtechnische Werke Fokker GmbH
Current assignee: Vereinigte Flugtechnische Werke GmbH; Vereinigte Flugtechnische Werke Fokker GmbH
Priority date: 1979-12-22
Filing date: 1980-12-12
Publication date: 1981-07-08
Also published as: CH649012A5; GB2066473B; DE2952232A1; DE2952232C2; AT380649B; ATA363680A

Abstract

Apparatus for measuring the gap between a pair of working rolls 7, 8 comprises two lever arms (1, 2) carrying sensors (5, 6) and arranged on the roll support by means of a common pivot bearing (3), a measuring device (23) being provided on one lever arm (1) for producing an actual value signal representative of the roll gap and the other lever arm (2) displacing a rack (17) via a tensioned wire (14) for displacing the measuring device (23) without slip via a gear wheel (21). <IMAGE>

Description

SPECIFICATION A measuring arrangement for detecting the gap between a pair of working rollers The invention relates to a measuring arrangement for detecting the gap between a pair of working rolls and having two lever arms mounted on the roll support by a common pivot bearing and exhibiting sensors, on which is provided a measuring device detecting an actual value signal for a device controlling the roll gap.

It is usual in rolling mills to control the sheet thickness in order to achieve smaller sheet thickness tolerances. In order to achieve this, it is necessary to have a sufficiently rapid system of adjustment and to be able to detect the control magnitude as far as possible without delay besides the necessity of solving or satisfying the dynamic requirements of such a control process.

There are a number of measuring devices for measuring the roll gap in which two corresponding sensor elements measure the spacing between the working rolls without touching them. The measurement itself may be by inductors, capacitors or other suitable methods of measurement.

However, as is known from German Patent Specification No. 1931-654, there has recently been a clear trend in favour of inductive methods of measurement. The roll gap may be measured and controlled either by detecting the absolute spacing, as known from the above-mentioned specification, or by detecting the relative roll gap.

The latter method or technique is apparent from German Offenlegunsschrift No. 22 24 909.

Besides the previously mentioned methods of measurement, a so called fixed support roll gap measurement device is known from German Offenlegungsschrift No. 25 30 593. This roll gap measuring device comprises two lever arms, arranged on the roll support with a common pivot bearing and scanning the position of the working rolls by means of sensors. The measuring device also comprises two sensor elements which are not in contact and are arranged in each case on one lever arm and affect each other as a function of their mutual spacing and produce an analog electrical actual value signal.This roll gap measuring device has proved its worth in practice, since besides the accuracy which it can achieve, its construction is able to cope with rough operation of the rolling mill on the one hand and on the other hand does not prevent or hinder exchange of the rollers which is frequently necessary. In spite of these very good features, it is nevertheless unsatisfactory that this roll gap measuring device is unsuitable for digital roll gap control. As in many fields of technology, in roll gap measurement there is also the desire for digital control requiring digital roll gap measuring devices.

The invention seeks to provide a roll gap measuring device of the type stated at the outset which is in a position to detect the roll gap both in an analog and a digital manner.

According to the invention, there is provided a measuring arrangement for detecting the gap between a pair of working rolls comprising two lever arms, carrying sensors and arranged on the roll support by means of a common pivot bearing on a measuring device being provided on the lever arms for the purpose of producing an actual value signal for a device controlling the roll gap, wherein one of the lever arms has an operating element for displacing the measuring device arranged on the other lever arm, without slip.

It may be advisable to form the adjusting element of one lever arm as a toothed rack which meshes with a tensioned gear wheel of a producing shaft of the measuring device arranged on the other lever arm. The toothed rack may be connected to a load cable formed preferably as a steel wire, one end of the load cable being guided over a damping cylinder and deflection roller to a connecting point of the other lever arm and its other end being connected via a deflection roller and a tensioning device to the lever arm supporting the measuring device.

The invention will now be described in greater detail by way of example, with reference to the drawing, the single figure of which is a side view of a roll gap measuring device in accordance with the invention.

In the drawing a side view of a roll gap measuring device may be seen in which two lever arms 1, 2 are hinged on a common pivot bearing 3. The pivot bearing 3 has a flange 4 for connection to a roll support (not shown). The free ends of the lever arms 1, 2 are provided with movably connected sensors 5, 6, for scanning the position of the rollers, which sensors are situated on the bale ends 9, 10 of working roll 7, 8, as indicated. A pneumatic actuating cylinder 11 is provided for the purpose of pressing the sensors 5, 6 provided on the lever arms 1, 2 against the ends 9, 10, actuating cylinder 11 being pivoted to the upper lever arm 2. The piston rod 13 of the piston 12 provided in the operating cylinder 11 is also pivoted in fact is connected to the lower lever arm 1.Both lever arms 1, 2 are provided with appropriate recesses for the actuating cylinder 11.

A steel wire 14 serves as a load cable and is fixed to known means, (not shown) on the upper lever arm 2, on a level with the sensors 5, 6. This wire leads to a toothed rack 1 7 via a deflection roller 1 5 provided at the same level on the lower lever arm 1 and a damping and tensioning cylinder 1 6 is provided in this lever arm. The steel wire 14 is guided over a deflection roller 1 8 to a tension spring 19 at the other side of this toothed rack 1 7.

its other end being connected rigidly to the lever arm 1. The toothed rack 1 7 is guided in a rod guide 20 without any play and meshes in known manner, without play, with a gear wheel 21 which is seated on the positioning shaft 22 of a measuring sensor 23. For installation of the measuring sensor 23, appropriate recesses are provided in the lever arms 1, 2 and either digital measuring sensors or analog measuring sensors, e.g. a synchro, may be used. A conical spiral spring 25 and a bellows 24 lying over the spring 25 are provided between the deflection roller 1 5 and the connecting point on the upper lever arm 2 for the purpose of protecting the steel wire 14 and constitute an adequate safety measure for the steel wire 14, particularly when operation of the rolling mill is rough.The steel wire preferably comprises a thin spring steel wire of approximately 0.2 to 0.3 mm in thickness.

The roll gap measuring device in accordance with the invention is in a position to detect the roll gap either in analog or digital manner, as already mentioned. This depends merely on the respective measuring sensor which is used. The measuring sensor may be arranged also at the level of the deflection roller 1 5 transversely in the lower arm 1 and may be displaced by means of an approximately formed load cable. The function of the deflection roller 1 5 is taken over in this case by the drive wheel of the measuring sensor which is seated on the positioning shaft.In each case, the roll gap set between the working rolls 7, 8 is scanned by the sensors 5, 6 of the lever arms 1, 2 and transmitted to the gear wheel 21 of the measuring sensor 23 via the already tensioned steel wire 14 and the toothed rack 1 7. Rapid fluctuations in the roll gap do not result in natural oscillations since the damping device 1 6 passes on changes in the roll gap in damped form to the measuring sensor 23. The roll gap measuring device in accordance with the invention detects the absolute roll gap in each case without loss of the accuracy which accuracy depends solely on the accuracy of the measuring sensor.As compared to roll gap measuring devices with measuring sensors without contact, this roll gap measuring device has the advantage of always measuring with the same sensitivity, while this is not possible for example with inductive or capacitative methods of measurement because of the non-linearity of these methods of measurement. The feature of equal sensitivity within the measurement range makes it easier to carry out the required calibration process since the zero point and the related zero setting of the signal can be achieved, simply by moving the operating rollers together.In the roll gap measuring device in accordance with the invention the operating cylinder 11 provided there serves to draw together the lever arms 1, 2 or move them apart rapidly by acting in each case on one of the operating chambers and thus facilitates interchange of rollers which is often necessary in rolling mills.

The operating cylinder 11 then ensures that the sensors 5, 6 always abut the bale ends 9, 10 of the operating rollers 7, 8 during measurement and also ensures perfect detection of the actual value signal for a roll gap control device. The use of a synchro in conjunction with a synchro/digital converter is particulariy advantageous. This measuring sensor system provides an output signal which is not sensitive to interference and which is absolutely coded digitally, the said output signal can be further processed in one operation.

Claims

1. A measuring arrangement for detecting the gap between a pair of working rolls comprising two lever arms carrying sensors and arranged on the roll support by means of a common pivot bearing on a measureing device being provided on the lever arms for the purpose of producing an actual value signal for a device controlling the roll gap, wherein one of the lever arms has an operating element for displacing the measuring device arranged on the other lever arm, without slip.

2. A measuring arrangement according to claim 1 wherein one of the lever arms controls the position of a toothed rack which meshes with a tensioned gear wheel of a positioning shaft of the measuring device which is arranged on the other lever arm.

3. A measuring arrangement according to Claim 2, wherein the toothed rack is connected to a load cable one end of which is guided to a connecting point with the other lever arm via a damping and tensioning cylinder and a deflection roller and its other end is fixed to the lever arm supporting the measuring device via a deflection roller and a tensioning device.

4. A measuring arrangement according to Claim 3, wherein the load cable comprises a thin steel wire.

5. A measuring arrangement according to any one of Claims 1 to 4, wherein the measuring device comprises a measured value device producing digital actual value signals.

6. A measuring arrangement according to any one of Claims 1 to 4 wherein the measuring device comprises an analog measuring device.

7. A measuring arrangement according to Claim 6 wherein the measuring device is a synchro.

8. A measuring arrangement according to Claim 7, wherein the output signal of the synchro is supplied to a computing device of a digital device for controlling the roll gap via a synchro/digital converter.

9. A measuring arrangement for detecting tti1e gap between a pair of working rolls substantially as described herein with reference to the drawing.