DE3631643A1 - Device for the photoelectric temperature measurement of an object to be measured - Google Patents

Abstract

Device for the photoelectric temperature measurement of an object to be measured (4), in particular of metallurgical melts, having a radiation transmission device (1) which comprises light-conducting glass rods (5, 6a, 6b, 6c) and extends from the object to be measured (4) to a measured-value pickup (2). Diffusely scattering components, for example glass rods (6a, 6b, 6c) with matt-ground end faces, effect a uniform intensity distribution of the temperature radiation over the emergence plane (11) of the radiation transmission device (1). Two differently wavelength-selective pass filters (12, 13), arranged in the region of this emergence plane (11), split the temperature radiation, distributed uniformly according to the invention, into part-radiations of various wavelength ranges, the intensity ratio of which, detected by the two photo elements (15, 16) and processed in the signal further-processing device (3), represents a measure of the temperature of the object to be measured (4). <IMAGE>

Description

The invention relates to a device for photo electrical temperature measurement of a test object, especially of metallurgical melts, with a leading from the test object to a sensor Radiation transmission device, in particular from light-guiding glass rods, for transferring to a at or on the entry surface lying on the measurement object temperature radiation to the sensor.

It is known that from a heated test object outgoing radiation to determine its temperature to be used, especially when it comes to high Temperatures are like metallurgical Melting is the case.

For a non-contact measurement, for example is used for moving objects such as rolling stock, one uses measuring sensors, so-called color pyrometers, which are arranged at a certain distance from the measurement object are. Especially when measuring the temperature of metallurgical melting brings such a measurement However, there are disadvantages to this method: The only measurement location is the surface mostly covered with oxides and slag of the melt. In addition, the measurement result due to radiation from zones outside the ge desired measuring range in spite of the elaborate aperture device tals are falsified.

It has therefore already been suggested about temperature measurement of objects that are not or hardly moved, in particular metallurgical melting, radiation transmission directions, such as light-conducting glass rods, to provide the the temperature radiation of the object to be measured manage valuers. To measure the temperature of metallurgical melts carry these glass rods in space mean through the container wall to the outside, which also a temperature measurement inside or at the edge of the  Melt is possible. The measuring range (measuring surface) is thereby advantageously to the precisely defined one Entry surface of the radiation transmission device (e.g. end face of the glass rod) that is connected related, precisely defined. Annoying stranger Incidence of radiation can easily be avoided.

To such a radiation transmission device in principle many known color pyrometers connected be so-called two-color pyrometers an advantage are. In principle, these two-color pyrometers measure that Intensity ratio of the temperature radiation in two different wavelength ranges, whereby opposite the measurement in a wavelength range Measuring surface, weakening the light on the way to color pyrometer and the mostly not exactly known emission factor of the measurement object when determining the measurement result fall out. With such two-color Pyrometers need only be taken care that the formed in the pyrometer from the input radiation and part lying in different wavelength ranges radiations, the intensity ratio according to Principle of a two-color pyrometer for temperature measurement mood is used by the arriving Thermal radiation of one and the same measuring range or Part of the measuring range, otherwise it would lead to a ver falsification of the measurement result comes.

The majority of the known two-color pyrometers have movable, alternating in the beam path of one Different wavelengths inserted into the photo element selective filters to ensure that the ab alternating depending on the part formed filter Radiations from a temperature radiation from the same The measuring range or part of the measuring range originate. The evaluation (The measurement data are in both wavelength ranges not at the same time) is in these two-color pyro  meters difficult and for the detection of quick cooling not suitable. These pyrometers are also on Due to the moving parts technically complex, disturbing vulnerable and bulky.

The object of the invention is a technically simple and compact photoelectric temperature device to create measurement, particularly with regard to the preferred application in metallurgy robust and so that it is not susceptible to faults and which is an exact one Temperature measurement in a precisely defined measuring range allowed.

This is achieved in that the Radiation transmission device at least one diffuse scattering, optical component for uniform Intensity distribution of the temperature radiation over a has the exit surface facing the transducer and that the transducer in the area of this exit area at least two different wavelength selective, optical components, preferably pass filters, and at least one, preferably two photo element (s) for Reception of the components that are wavelength-selective contains outgoing partial radiation.

The invention is based on the idea of the measurement object radiation transmission leading to the sensor direction by placing a diffusely scattering component on it has to train such that a more robust, easier and also smaller, according to the principle of a two-color or multicolor pyrometers working sensor with fixed wavelength-selective, optical Components (preferably pass filters) and at least one photo element (preferably two photo elements) can be used without losing measuring accuracy, whereby also very rapid temperature changes of the test object are detectable.  

Through the diffusely scattering component, the simplest Case made from a glass rod with a matte finish Surface exists, can be reached in any wavelength uniform intensity distribution over the area Output surface facing the transducer, so that on all arranged in this area, different waves length-selective components on the input side each Temperature radiation with the same intensity meets. This ensures that the intensity ratio of the output side from these components partial radiations actually a measure of the Temperature of the measurement object on the measurement surface.

In the following, each electromagnetic is under light Radiation understood. In particular, are light guides not just components used to guide visible light are suitable, but components that any other electromagnetic radiation, especially infrared Can conduct radiation.

The different from the wavelength-selective, optical Partial radiation emanating from components can ripple overlap in length, i.e. Shares with the same waves have length, but also in completely separate waves length ranges.

The evaluation of the starting from the photo elements electrical signals are particularly simple, if any wavelength selective optical component at least one photo element for receiving the from this outgoing partial radiation is assigned, where Photo diodes due to their linear characteristic (current proportional to the radiation intensity) appear.

Suitable as wavelength-selective, optical components for the arrangement according to the invention in addition to pass filters  also selectively reflecting mirrors.

At the exit side of this wavelength selective construction parts can be according to a preferred feature of the invention be provided to prevent interference between the partial radiations preferably glass fiber Optical light guides are provided by the respective Wavelength-selective, optical component at least a photo element.

A particularly compact and small sensor, in metallurgy, especially when it comes to measurements small test jars are suitable, where the radiation transfer support devices small sizes, about in centi meter range can be achieved that the photo elements directly to the respective waves Adjacent length-selective components.

This small device with a small measured value and a simple and cheap radiation transfer Carrier device can also be used for temperature measurement be used on real castings (surface), by being moldable in the core and / or molding sand are. Correspondingly isolated and attached Ver small sensors after cooling again be applied.

Since the radiation transmission device is mainly on their entrance surface, for example by a molten metal is heavily loaded or no longer after the measuring process is a preferred embodiment the invention that the radiation transmission direction at least two in the beam path behind has mutually lying light guide elements from which at least one is releasably connected to the others is. The light in contact with the measurement object conductor element can e.g. on for measurements on metallur  the usual melting refractory glass rod, which is lost with each or after a few measurements. The rest of the device, i.e. another light guide element or the optically scattering component and the adjoining sensor, can by the Detachable attachment to the glass rod mentioned above can be used after the measurement or for several existing measuring objects can be used by e.g. to one each with these test objects tied light guide element and after the measurement process resolves again.

Especially with a detachable part of the Radiation transmission device connected, for example wise pluggable sensor, it is an advantage that the photo element (s) to one that has a predetermined period of time registered measurement data, preferably wise in digital form, storing, for example battery powered portable storage device connected. Without problems with long cables or to have bulky evaluation devices Measurement sensor (including storage device) at most with part or all of the radiation transmission device for registration of measurement data to not or only difficult to move objects or at there fixed brought fiber optic elements are connected. The The stored data is then evaluated on a central evaluation unit.

Assign the light guide elements of the radiation transfer carrying device on a similar diameter, so can be a heat-resistant protective tube in a particularly favorable Way for a plug connection of the light guide elements be used by putting the junction outside surrounds.

With the device according to the invention are not only  Surface temperatures measurable, but for example also temperatures in the middle of the melt pool. To do this extends the radiation transmission device into the Melt and is up to an entry area of one surround a radiation-preventing envelope.

The diffusely scattering component (s) can be one diffuse scattering surface area, such as a matte have a ground or etched surface, whereby several such components, for example glass rods matted end faces, one behind the other in the beam path can be arranged. But it can alternatively or additionally a component made of light-diffusing material be provided (diffusing glass, volume spreader).

To prevent that from existing, if not diffuse scattering sections of the radiation transmission device is uneven across the cross-section Intensity distribution results, which then also at the beginning abuts on the wavelength-selective components and thus falsifies the measurement result, sees another preferred embodiment of the invention that at least one diffusely scattering component in the area of outlet surface of the sensor pointing Radiation transmission device is arranged and preferably forms this exit surface. It is it’s also convenient if the wavelength selective, optical components directly to the exit surface of the Adjacent radiation transmission device.

Of course, those of the photo elements outgoing electrical signals directly or after Intermediate storage on an above storage device from an evaluation device (e.g. with linear preamplifiers and a logarithmic Differential amplifier) and the measuring results displayed, printed out or otherwise  (e.g. for temperature control).

Details of the invention are based on execution examples by the figures of the drawing he closer purifies. It shows

Fig. 1 is a schematic sectional view of an inventive device from the execution example for temperature measurement including the attached storage and evaluation circuit,

Fig. 2 shows a section according to the line AA of Fig. 1

Fig. 3 is an enlarged view of the transducer and a part of the radiation transmission means of the device shown in FIG. 1,

5 further embodiments of FIGS. 4 and Fig. Of optically scattering or components of the transducer,

Fig. 6 and Fig. 7 for direct measurement on the casting in the upper box or in the core molded transducer.

The apparatus shown in Fig. 1 for photoelectric temperature measurement consists essentially of a transducer 2, and a radiative tragungseinrichtung 1 having the (a metallurgical melt, in this case) from continuous thermal radiation leads from the measured object 4 to the transducer 2, which in its entirety with the reference number 3 be designated signal processing devices is connected.

The radiation transmission device 1 has four light guide elements 5 , 6 a , 6 b and 6 c, one behind the other in the beam path, made of refractory quartz glass (cylindrical glass rods). Here, the glass inlet side location is rod 5 by means of sizing 7 firmly into the wall 8 of synthetic resin-bonded silica sand of the melt 4 receiving sample crucible glued, while the remaining radiation transmission device 1 together with the transducer 2 detachably with this glass rod 5 is connected, namely, with the front part of the Protective tube 9 can be plugged onto this glass rod 5 . Between the protective tube 9 made of metal or ceramic and the light guide elements 5 , 6 a , 6 b and 6 c there are retaining straps 10 made of heat-resistant material. After the melt 4 solidifies in the test crucible, the glass rod 5 is generally no longer usable, while the rest of the device remains undamaged and can be used further.

The components of the invention, in the Strahlungsübertragungsein device 1 arranged, diffusely scattering, optical, in the present embodiment of the light guide elements 6 a, 6 b and 6 are formed c whose end faces satin finished and etched, and thus are diffusely scattering to a uniform intensity distribution of the radiation temperature on the transducer 2 which faces the exit surface 11 of the radiation transmission device and thus the entire entry surface (see. also FIG. 2) of the directly adjacent, different wavelength selective transmission filter 12, 13, the transducer, the wavelength-selective optical components of the measurement value 2 form, to reach . In the present exemplary embodiment, the pass filter 12 is a filter of the RG 830 type which transmits light with a wavelength of over 800 mm, while the pass filter 13 is of the KG 1 type and transmits light of 250 to 600 mm.

The last diffusely scattering component (light guide element 6 c) - as is also shown in FIG. 3 - forms the exit surface 11 with its matte end face facing the measuring sensor 2 .

In the transducer 2 , which is surrounded by a protective sheath 14 only shown in FIG. 1, the temperature radiation of the test object 4 , which is uniformly distributed over the entrance surface, is measured by the two wavelength-selective transmission filters 12 , 13 in partial radiation in two different wavelength ranges divided, the respectively associated with a passage filter 12 or 13 and directly adjacent photodiodes 15, 16 determine the intensities of the partial radiations independently of one another and corresponding electrical signals, the ratio of which represents a measure of the temperature of the test object 4 at the entry surface of the glass rod 5 ( Principle of a two-color pyro meter) to which signal processing devices 3 are connected via plug connections 17 , 18 and lines 19 , 20 . A reflective separating film 21 prevents, in a manner known per se, undesired interference between the two partial radiations lying in different wavelengths.

A first variant of the signal processing devices consists in a battery-operated, portable storage device 22 , which digitizes the measurement signals of the photodiodes 15 , 16 over a certain period of time in an analog-to-digital converter 22 a and temporarily stores them in a storage part 22 b . Especially when measuring on immovable objects, long cables can be avoided, which lead to the actual evaluation device 24 , which is also usually not or only difficult to move. In addition, the evaluation circuit does not need to be taken into the danger zone of a workshop, for example, where the measurement takes place, for example, on a melt. After the measurement, you put the memory device 22 only by means of a multi-channel connector 23 in a multi-channel sleeve 23 'to the off evaluation circuit (such as a central computer), processed, whereupon the stored measurement data and a visual display device 25 or a printer 26 can give out .

In smaller laboratories or while continuously monitoring the objects to be measured, however, direct measurement data acquisition can also be advantageous. In the present embodiment example (dashed lines in Fig. 1), an analog-to-digital converter 27 is provided for this purpose, which can of course also be integrated into the evaluation device 24 . In addition to the ongoing display of the measurement data on an optical display device 25 or a printer 26 , there is of course also the possibility, depending on the speed of the measured temperature of the measurement objects, to carry out certain control functions by means of a control device 28 .

Fig. 4 shows the transducer 2 and part of the radiation transmission device 1 of another embodiment. The same or equivalent parts are designated in the same way as in FIGS . 1 to 3. While in the exemplary embodiment shown in FIGS . 1 to 3, the scattering of the thermal radiation mainly on the matt end faces of the light guide elements 6 a , 6 b and 6 c , the radiation transmission device according to FIG. 4 has a separate scatter glass 6 'made of light-scattering material in order to achieve a uniform intensity distribution of the radiation over the entire exit surface 11 of the radiation transmission device.

In the embodiment shown in Fig. 5, such a diffusing glass 6 'is also provided. The sensor 2 , however, has photodiodes 15 , 16 which do not directly adjoin the pass filters 12 , 13 , but are connected to these pass filters 12 , 13 for thermal or structural reasons via flexible, glass fiber optic light guides 29 , 30 . The light filters 29 , 30 conduct the partial radiation emanating from the transmission filters 12 , 13 to the assigned photodiodes 15 , 16 without interference.

In addition to the measurement on a melt in a test crucible, for example for determining the solidification behavior, the small device according to the invention is also particularly suitable for measurements directly on the real casting 35 or its surface, the entire device 1 , 2 for example in the molding sand of the upper box 36 ( Fig. 6) or in the core 37 ( Fig. 7) can be molded. The electrical measurement signals arrive via schematically Darge lines 19 , 20 in a battery-operated, portable storage device 22 , which can be connected in the following to a central evaluation device, not shown. After solidification of the casting is the foremost part of the Strahlungsübertragungsein direction one is no longer usable, but probably the most suitable insulated transducer 2 and at most a part of the facing direction Strahlungsübertragungsein first

Of course, especially in the case of thin top and bottom box walls, there is also the possibility of shaping only the radiation transmission device 1 and arranging the measurement receiver 2 on the outside. Glass fiber optic light guides known per se are also possible.

The device according to the invention is both in the An application as well as in the construction not on the described Embodiments limited. For example, you can also not radiated, but selectively reflective Components used as wavelength-selective components will. The radiation transmission device can be flat if constructed differently, especially what the diffuse scattering components. Finally, are suitable in addition to photodiodes, of course, others as such known photo elements such as phototransistors etc.

Claims (13)

1. Device for photoelectric temperature measurement of a measurement object, in particular of metallurgical melts, with a radiation transmission device leading from the measurement object to a measurement value, in particular from light-conducting glass rods, for transmitting the temperature radiation incident on an entry surface lying on or at the measurement object to the measurement sensor, thereby characterized in that the radiation transmission device ( 1 ) has at least one diffusely scattering, optical component ( 6 a , 6 b , 6 c , 6 ') for uniform intensity distribution of the temperature radiation over an exit surface ( 11 ) facing the transducer ( 2 ) and that the transducer ( 2 ) in the area of this exit surface ( 11 ) at least two different wavelength-selective optical components ( 12 , 13 ), preferably transmission filter, and at least one, preferably two photo element (s) ( 15 , 16 ) for receiving the waves length-selective component len ( 12 , 13 ) outgoing part contains radiation. 2. Device according to claim 1, characterized in that at least one of the wavelength selective, optical components a selectively reflective Mirror is. 3. Apparatus according to claim 1 or 2, characterized in that to prevent interference between the partial radiations preferably glass fiber optical light guides ( 29 , 30 ) are provided, which from the respective wavelength-selective optical component ( 12 , 13 ) to at least one photo element ( 15 , 16 ) lead. 4. Device according to one of claims 1 to 3, characterized in that the photo elements ( 15 , 16 ) directly adjoin the respective wavelength-selective components ( 12 , 13 ). 5. Device according to one of claims 1 to 4, characterized in that the or the photo elements ( 15 , 16 ) to one, the recorded over a predetermined period of measurement data, preferably in digital form, storing, for example battery operated, portable storage device ( 22 ) are connected. 6. Device according to one of claims 1 to 5, characterized in that the radiation transmission device ( 1 ) has at least two light guide elements ( 6 a , 6 b , 6 c) located one behind the other in the beam path, of which at least one ( 6 a) is detachable connected to the others ( 6 b , 6 c) . 7. A device for measuring the temperature of metallurgical shear, according to one of claims 1 to 6, characterized in that the radiation transmission device ( 1 ) extends into the melt ( 4 ) and in the area surrounded by the melt except for the entry surface of one a sheath preventing radiation entry is surrounded. 8. Device according to one of claims 1 to 7, characterized in that at least one scattering component ( 6 a , 6 b , 6 c) has a diffusely scattering surface area. 9. Device according to one of claims 1 to 8, characterized in that at least one component consists of a irradiated, light-guiding glass rod ( 6 a , 6 b , 6 c) with a ground and / or etched entry and / or exit surface. 10. Device according to one of claims 1 to 9, characterized in that several glass rods ( 6 a , 6 b , 6 c) with matt end faces are arranged one behind the other in the beam path as diffusely scattering components. 11. Device according to one of claims 1 to 10, characterized in that at least one diffusely scattering component, for example a diffusing glass ( 6 ') consists of a light-scattering material. 12. Device according to one of claims 1 to 11, characterized in that at least one diffusely scattering component (6 c, 6 ') in the region of the side facing the sensor (2) exit surface (11) of transmission of the radiation is disposed (1) and before preferably forms this exit surface ( 11 ). 13. Device according to one of claims 1 to 12, characterized in that the wavelength-selective, optical components ( 12 , 13 ) directly adjoin the exit surface ( 11 ) of the radiation transmission device ( 1 ).