GB2235051A

GB2235051A - Strip temperature measurement

Info

Publication number: GB2235051A
Application number: GB9014733A
Authority: GB
Inventors: Peter David Spooner; William John Edwards
Original assignee: BRONER CONSULTANTS Ltd
Current assignee: BRONER CONSULTANTS Ltd
Priority date: 1989-07-03
Filing date: 1990-07-03
Publication date: 1991-02-20
Anticipated expiration: 2010-07-03
Also published as: GB8915256D0; GB9014733D0; GB2235051B

Abstract

The temperature pattern across a strip 2 of material passing over a roll 4 is determined by measuring surface temperatures of different parts of the roll 4. A series of sensors 7 extending axially across the roll downstream from the point 6 of strip-roll contact make the measurements. Means are provided to determine the strip temperature pattern from these measurements. The sensors 7 are supported on an air-cushion close to, but not touching, the roll surface. <IMAGE>

Description

STRIP TEMPERATURE MEASUREMENT This invention relates to an apparatus for measuring the temperature of strip material as it passes under tension over a roll.

The process of rolling strip material is complicated and requires many delicate and precise measurements and adjustments to the various control factors. One of these factors is measuring the temperature of the strip as it is being rolled. It is well known to modify the rolling operation to account for variation in the flatness or "shape" of the strip. However, to take full advantage of flatness measurement it is desirable to measure the temperature distribution across the width of the strip as the strip can warp while cooling down.

Many different devices have been used in order to measure the temperature of the strip as a preliminary to overcoming the problem of warping during cooling.

Non-contact radiation pyrometers are the most usual devices employed. They have the advantage that they can be located away from the strip and so escape the possibility of damage should the strip break. However, they do suffer from a lack of accuracy as they rely on the emissivity of the surface of the strip being constant. As the temperature of the strip varies considerably the pyrometer is not therefore able to detect the precise temperature.

Another more accurate device employed relies on convection currents. The device measures a thin film of air very close to the surface of the strip. The use of such a device would, however, render it very vulnerable in the event of a strip breaking.

Accordingly the present invention provides a temperature measuring apparatus for strip material passing under tension over a roll comprising a series of sensors arranged in series axially in association with a surface of the roll and positioned after a region of contact between the strip and the roll such that each sensor ca measure the surface temperatures of different parts of the roll corresponding with parts of the strip aligned therewith and means to determine the temperature pattern across the strip from said surface temperature.

The process of rolling strip material requires that the material pass over and so make contact with, often at great speeds, a number of roll works which act to e.g.

flatten, realign and/or direct the material as required.

These roll works are arranged so as to manipulate the strip material to the correct shape.

However the temperature distribution of the strip material transfers to the surface of the roll over which it passes. Measurement of this temperature distribution across the roll would thus be a good indication of the temperature across the strip in contact with the roll.

Correction could then be made mathematically for any deviation from the true value due to, for example, wrap angle and/or heat transfer coefficient.

In a preferred embodiment a series of non-contact temperature sensors are supported in a housing on an air cushion. The sensors are positioned axially along and close to but not touching the surface of the roll after the region of contact between the roll and the strip.

Here the sensors make use of convection currents by measuring the temperature of a thin layer of air very close to the surface of the roll. The support provided by the air cushion also ensures the roll surface remains unaffected by the sensors.

One application of the present invention will now be described by way of example with reference to the accompanying drawing, in which: Figure 1 is a front elevational view of a series of temperature sensors; and Figure 2 is a cross-section along the line II-II and also includes a roll with a strip in contact therewith.

Referring generally to the drawing the present invention part of a strip rolling mill is indicated at 1 and comprises a strip 2 passing over the outer surface 3 of a roll 4. A temperature sensing device 5 is positioned adjacent the roll 4 after the region of contact 6 between the strip 2 and the roll surface 3 so as to be close to but not touching the roll surface 3 of the roll 4. The temperature sensing device 5 is arranged axially above the roll surface 3.

The temperature sensing device 5 comprises a series of sensors 7 arranged on a backing 8 and housed within a container 9. The container 9 has back, front and end walls 10, 11, 12 and 13 respectively and the front wall 11 has pposing sides 14 and 15 which define an opening 16 through which the sensors 7 protrude.

With specific reference to Figure 2 an air cushion 17 supports the sensors 7 within the container 9, and is substantially enclosed between the back and end walls 10, 12 and 13 of the container 9 and the backing 8 of the sensors 7.

Each sensor 7 supported on the air cushion 17 comprises a circular ceramic sensing head containing a centrally mounted thermocouple.

A pressurised incoming air supply for the air cushion 17 enters to the rear of the sensor and passes through the sensing head by way of a plurality of apertures. The apertures are arranged in a ring on a front of the sensing head.

The incoming air supply urges the sensor towards the roll surface and through the opening 16 in the container 9 housing the sensors 7.

Exiting air from the apertures forms a thin layer over the front of the sensing head. As this layer is in close proximity to the surface of the roll the heat from the roll is transferred to the air supply.

The layer of air also helps to prevent the sensor from touching the roll surface. The layer of air is extremely thin being in the order of 150 microns.

The thermocouple is housed within the sensing head and an opening in the front thereof allows contact between the exiting heated air and the thermocouple.

The exiting air in addition to passing over the thermocouple can follow a plurality of vent means leading from the opening to the rear of the sensor.

The sensors 7 can therefore measure the temperature of the roll surface 3, this temperature being a measure of the temperature of the strip 2 which passes over the roll 4, the strip 2 having transferred its temperature distribution to the roll surface 3.

Claims

CLAIMS:

1. A temperature measuring apparatus for strip material passing under tension over a roll comprising a series of sensors arranged in series axially in association with a surface of the roll and positioned after a region of contact between the strip and the roll such that each sensor can measure the surface temperatures of different parts of the roll corresponding with parts of the strip aligned therewith and means to determine the temperature pattern across the strip from said surface temperatures.

2. Apparatus as claimed in claim 1, wherein the temperature sensors are supported in a housing on an air cushion and are arranged axially along and close to but not touching the surface of the roll.

3. Apparatus as claimed in claim 2, wherein the temperature sensors supported on an air cushion each comprise a sensing head containing a centrally mounted thermocouple.

4. Apparatus as claimed in claim 3 wherein pressurised incoming air supply is arranged to enter to the rear of the sensor and passes through the sensing head by way of a plurality of apertures, the incoming air urging the sensor towards the roll surface.

5. Apparatus as claimed in claim 4, wherein the apertures are arranged in a ring on a front of the sensing head and from which exiting air forms a thin layer of air over the front of the sensing head.

6. Apparatus as claimed in claim 4 or 5, wherein an opening in a front of the sensing head allows for contact between the exiting air, heated by proximity to the roll surface, and the thermocouple.

7. Apparatus as claimed in claim 6, wherein the exiting air is arranged to follow a plurality of vent means leading from the opening to the rear of the sensor.

8. A temperature measuring apparatus, substantially as hereinbefore described with reference to the accompanying drawing.