GB1582889A

GB1582889A - Temperature determination

Info

Publication number: GB1582889A
Application number: GB4703877A
Authority: GB
Original assignee: British Steel Corp
Current assignee: British Steel Corp
Priority date: 1978-05-23
Filing date: 1978-05-23
Publication date: 1981-01-14

Description

(54) TEMPERATURE DETERMINATION (71) We, BRITISH STEEL CORPOR ATION, a Corporation incorporated and existing under the Iron and Steel Act 1967 whose'principal office is at 33 Grosvenor Place, London, S.W.1 7JG, England, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, .to be particularly described in and by the following statement: This invention relates to temperature determination. In particular, it is concerned with a temperature. measuring device, such as a pyrometer, which is scanned through a predetermined angle across the path of a body.The invention is particularly suitable for determining the temperature of a hot steel section whilst it is passing towards or away from a rolling mill stand. It may also be used however in the measurement of the temperature of other moving bodies, such as a sinter strand.

According to one aspect of the invention apparatus for determining the temperature of a moving body includes a temperature sensing device adapted to be scanned across the path of the body, said temperature sensing device providing in use an electrical output characteristic of the temperature of the body, and means for reversing the direction of scan of the temperature sensing device in response to said electrical output indicating that the scan has reached a perimeter of the body.

The temperature sensing device is typical ly a pyrometer of the optical type.

The pyrometer may be pivotally mounted to a reciprocable actuator whereby to effect the scanning of the pyrometer across the path of the body.

The maximum scan of the pyrometer may be determined by limit switches or other similar devices which can be preset at the maximum extent of the scan.

The means for reversing the direction of scan may ihclude a microprocessor which is linked to the reciprocating actuator to effect the reversal.

The apparatus may include means for switching off the actuator after a predetermined time period or number of scans during which the pyrometer has not had sight of a moving body.

The apparatus may further include a photodetector for initiating the scan of the pyrometer prior to the body enterìng the field of view of the pyrometer.

The apparatus may form part of a system for indicating the end of a period over which a body is estimated to have cooled from a higher temperature to a pre-set lower temperature, as described or clairned in British patent specification 1,482,185. The present invention includes a combination of such a system with apparatus as defined in the preceding paragraphs.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a scanning pyrometer and- its associated controls; Figure 2 is a schematic diagram df the scan reversal system for the pyrometer of Figure 1.

A pneumatically operable piston and cylinder assembly 10 has a piston rod 11 which is pivotally linked to a swinging arm 12. The piston and cylinder assembly 10 is seen in Figure 2 as the scanner actuator. A pyrometer 13 is mounted at the lower end of the arm 12 and is directed towards the path of a moving body (not shown) beneath the pyrometer 13. Operation of the piston and cylinder assembly 10 causes the pyrometer 13 to swing in a vertical plane.

A pair of limit switches, 14 and 15 respectively, are located at fixed positions on either side of the arm 12. When the arm 12 comes into contact with either of these switches 14, 15, a pneumatic signal is transmitted to a pneumatic controller 16 which causes the air supply to the piston and cylinder assembly 10 to be switched. This switching reverses the direction of movement of the piston rod 11. The pyrometer (in the absence of further controls) will therefore scan a fixed path determined by the piston of the limit switches 14 and 15.

The output from the pyrometer 13 (also called the scanner signal) is fed by appropriate leads 17 through a lineariser 18 (see detail of Figure 2) to a microprocessor 19.

The lineariser 18 is used because the voltage output of the pyrometer 13 is non-linear with respect to the sensed temperature, and a standard Land model is employed to obtain a linear signal. Within the microprocessor the temperature of the sensed body is determined and fed to an electronic controller 20.

The direction in which the pyrometer 13 is swinging can be determined by a scanner direction sensor 21 which is fitted to the pneumatic controller 16. The output from the scanner direction sensor 21 is fed to the electronic controller 20 within the microprocessor 19. One of the functions of the electronic controller 20 is to generate a control signal in response to sharp drops in the output of the pyrometer 13. This control signal has two forms, depending upon the input to the electronic controller 20 from the scanner direction sensor 21. For example, the trailing edge of the signal from the pyrometer 13 can trigger a monostable circuit to drive a solenoid to operate the appropriate valves to control the scanner actuator 10.If the scanner is -moving, say, to the left, when there is a sharp drop in the output of the pyrometer 13, then the control signal generated by the electronic controller 20 will, when supplied to the pneumatic controller, cause the scanner actuator 10 to reverse -the direction of movement, and move the pyrometer 13 to the right. This ensures that the pyrometer spends the majority of the time viewing the body whose temperature is to be determined, rather than only a limited percentage. The invention is particularly useful where the scan of the pyrometer has to be a large angle because the exact position of the body is uncertain.A photosensor 22 or other similar device can be used to detect the presence of the body as it approaches the pyrometer 13, and the output from the photoscanner 22 can be fed to the microprocessor 19 which ensures that the pyrometer 13 commences scanning. The pyrometer then effectively "locks-into" the body until it leaves its field of view, and the microprocessor 19 can be adapted so as to stop the scanning of the pyrometer 13 after say.a further five scans.

Where suitable, the apparatus described above can be combined with the invention described in our patent no. 1,482,185 which is hereby incorporated into the present specification by reference.

WHAT WE CLAIM IS: 1. Apparatus for determining the temperature of a moving body . including a temperature sensing device adapted to be scanned across the path of the body, said temperature sensing device providing in use an electrical output characteristic of the temperature of the body, and means for reversing the direction of scan of the temperature sensing device in response to said electrical output indicating that the scan has reached a perimeter of the body.

2. Apparatus as claimed in claim 1 in which the temperature sensing device is a pyrometer of the optical type.

3. Apparatus as claimed in claim 2 in which the pyrometer is pivotally mounted to a reciprocable actuator whereby to effect.

the scanning of the pyrometer across the path of the body.

4. Apparatus as claimed in claim 2 or claim 3 in which the maximum scan of the pyrometer is determined by limit switches which can be. pre-set at the maximum extent of the scan.

5. Apparatus as claimed in any preceding claim in which the means for reversing the direction of scan includes a microprocessor which is linked to the reciprocating actuator to effect reversal.

6. Apparatus as claimed in any of claims 3 to 5 including means for switching off the actuator after a pre-determined time period or a number of scans during which the pyrometer has not had sight of a moving body.

7. Apparatus as claimed in any preceding claim including a photo-detector for initiating the scan of the temperature sensing device prior to a body entering the field .of view to the temperature sensing device.

8. Apparatus as claimed in any preced ing claim in conjunction with a device for indicating the end of a period over which a body is estimated to have cooled from a higher temperature to a pre-set lower temperature, as described or claimed in British Patent Specification 1482185.

9. Apparatus for determining the temperature of a moving body as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

12 comes into contact with either of these switches 14, 15, a pneumatic signal is transmitted to a pneumatic controller 16 which causes the air supply to the piston and cylinder assembly 10 to be switched. This switching reverses the direction of movement of the piston rod 11. The pyrometer (in the absence of further controls) will therefore scan a fixed path determined by the piston of the limit switches 14 and 15.

The output from the pyrometer 13 (also called the scanner signal) is fed by appropriate leads 17 through a lineariser 18 (see detail of Figure 2) to a microprocessor 19.

The lineariser 18 is used because the voltage output of the pyrometer 13 is non-linear with respect to the sensed temperature, and a standard Land model is employed to obtain a linear signal. Within the microprocessor the temperature of the sensed body is determined and fed to an electronic controller 20.

The direction in which the pyrometer 13 is swinging can be determined by a scanner direction sensor 21 which is fitted to the pneumatic controller 16. The output from the scanner direction sensor 21 is fed to the electronic controller 20 within the microprocessor 19. One of the functions of the electronic controller 20 is to generate a control signal in response to sharp drops in the output of the pyrometer 13. This control signal has two forms, depending upon the input to the electronic controller 20 from the scanner direction sensor 21. For example, the trailing edge of the signal from the pyrometer 13 can trigger a monostable circuit to drive a solenoid to operate the appropriate valves to control the scanner actuator 10.If the scanner is -moving, say, to the left, when there is a sharp drop in the output of the pyrometer 13, then the control signal generated by the electronic controller

20 will, when supplied to the pneumatic controller, cause the scanner actuator 10 to reverse -the direction of movement, and move the pyrometer 13 to the right. This ensures that the pyrometer spends the majority of the time viewing the body whose temperature is to be determined, rather than only a limited percentage. The invention is particularly useful where the scan of the pyrometer has to be a large angle because the exact position of the body is uncertain.A photosensor 22 or other similar device can be used to detect the presence of the body as it approaches the pyrometer 13, and the output from the photoscanner 22 can be fed to the microprocessor 19 which ensures that the pyrometer 13 commences scanning. The pyrometer then effectively "locks-into" the body until it leaves its field of view, and the microprocessor 19 can be adapted so as to stop the scanning of the pyrometer 13 after say.a further five scans.

Where suitable, the apparatus described above can be combined with the invention described in our patent no. 1,482,185 which is hereby incorporated into the present specification by reference.

WHAT WE CLAIM IS: 1. Apparatus for determining the temperature of a moving body . including a temperature sensing device adapted to be scanned across the path of the body, said temperature sensing device providing in use an electrical output characteristic of the temperature of the body, and means for reversing the direction of scan of the temperature sensing device in response to said electrical output indicating that the scan has reached a perimeter of the body.
2. Apparatus as claimed in claim 1 in which the temperature sensing device is a pyrometer of the optical type.
3. Apparatus as claimed in claim 2 in which the pyrometer is pivotally mounted to a reciprocable actuator whereby to effect.

the scanning of the pyrometer across the path of the body.
4. Apparatus as claimed in claim 2 or claim 3 in which the maximum scan of the pyrometer is determined by limit switches which can be. pre-set at the maximum extent of the scan.
5. Apparatus as claimed in any preceding claim in which the means for reversing the direction of scan includes a microprocessor which is linked to the reciprocating actuator to effect reversal.
6. Apparatus as claimed in any of claims 3 to 5 including means for switching off the actuator after a pre-determined time period or a number of scans during which the pyrometer has not had sight of a moving body.
7. Apparatus as claimed in any preceding claim including a photo-detector for initiating the scan of the temperature sensing device prior to a body entering the field .of view to the temperature sensing device.
8. Apparatus as claimed in any preced ing claim in conjunction with a device for indicating the end of a period over which a body is estimated to have cooled from a higher temperature to a pre-set lower temperature, as described or claimed in British Patent Specification 1482185.
9. Apparatus for determining the temperature of a moving body as hereinbefore described with reference to and as shown in the accompanying drawings.