Optical pyrometer

Abstract

A device for measuring the temperature of a bath of metal contains a sleeve and an optical head. The sleeve and optical head may be joined together or taken apart by rotation with respect to each other. The sleeve is made at least partially of a refractory material. A method for measuring the temperature of a bath of molten metal makes use of the inventive device. By virtue of this device, mounting and removal is rendered easier while keeping the measuring zone centered and decreasing measurement disturbances caused by the emission of gas from the sleeve.

Claims

1. Device for measuring the temperature of a bath of molten metal, comprising: a) a sleeve made at least partially of refractory material and having: an open end provided with at least one notch, a closed end, a longitudinal axis, a main internal bore extending from the open end to the closed end along the longitudinal axis of the sleeve, an inlet portion of the internal bore that is spaced apart from the open end of the sleeve, wherein the bore has grooves disposed along the lengthwise direction of the inlet portion, wherein the grooves are angularly offset from said at least one notch in the open end, and wherein the grooves are configured to guide pins of a head of a bayonet rod into a blocking portion of the internal bore that has a cross section larger than the smallest cross section of the internal bore and a sufficient height to allow the relative rotation of the pins of the bayonet rod with respect to the sleeve about the longitudinal axis of the sleeve, and b) an optical head comprising: a hollow bayonet rod having an end provided with pins, and another end which accommodates a lens holder closed off by a protective window and a pyrometer lens, the intermediate part of the bayonet rod being disposed in the center of a spring supported by a locking component which: is free to rotate about the bayonet rod, is secured to a spring tensioner, is secured to a locking component rotator, and has at least one peg configured to be accommodated in said at least one notch in the sleeve, the locking component configured to be pivoted: from a starting position in which the peg of the locking component is in line with the notch in the sleeve and the pins of the bayonet rod are in line with the grooves, to a position angularly offset from the starting position, in which the pins of the bayonet rod are in the blocking portion of the internal bore in a position offset from the grooves.

2. Device according to claim 1, wherein the lens holder has a wall comprising lateral channels configured to allow the passage of a gas that cools the lens of the pyrometer and sweeps across the protective window.

3. Device according to claim 1, wherein the bore in the inlet portion spaced apart from the end of said sleeve is frustoconical.

4. Device according to claim 1, wherein the end of the locking component is conical.

5. Device according to claim 1, wherein the spring tensioner and the locking component rotator is a lever.

6. Device according to claim 1, wherein a vent tube is interlocked with the bayonet rod.

7. Sleeve made at least partially of refractory material and configured to be accommodated in a device according to claim 1, having: an open end provided with at least one notch, configured to accommodate a peg of an optical head, a closed end, a longitudinal axis, a main internal bore extending from the open end to the closed end along the longitudinal axis of the sleeve, an inlet portion of the internal bore that is spaced apart from the open end of the sleeve, the bore having grooves disposed along the lengthwise direction of the inlet portion, wherein the grooves are angularly offset from said at least one notch in the open end, the grooves being configured to guide the pins of a head of a bayonet rod into a blocking portion of the internal bore that has a cross section larger than the smallest cross section of the internal bore and a sufficient height to allow the relative rotation of the pins of the bayonet rod with respect to the sleeve about the longitudinal axis of the sleeve.

8. Sleeve according to claim 7 made at least partially of a refractory material, wherein a single notch is provided.

9. Sleeve according to claim 7, comprising a refractory material.

10. Sleeve according to the claim 7, wherein the bore in the inlet portion spaced apart from the end of said sleeve is frustoconical.

11. Stopper rod comprising a sleeve according to claim 7.

12. Method for assembling a temperature-measuring device according to claim 1, the method comprising the following steps of: providing an optical head and a sleeve, fitting the optical head into the sleeve, fixing the sleeve by rotation thereof, causing the rotation of the spring tensioner of the optical head, and decompressing the spring.

13. Method for disassembling a sleeve from an optical head of a temperature-measuring device according to claim 1, the method comprising the following steps of compressing the spring, pivoting the spring tensioner so as to return to the initial position of the spring tensioner, causing the disconnection of the sleeve, disengaging the sleeve.

14. Method for measuring the temperature of a bath of molten metal with a temperature-measuring device according to claim 1, comprising the following steps of: providing an optical head, providing a sleeve, assembling the sleeve to the optical head to produce a temperature-measuring device according to claim 1 by rotating the sleeve with respect to the optical head, causing the rotation of the spring tensioner of the optical head, decompressing the spring, positioning the assembly in the bath of molten metal, measuring the temperature.

15. Device according to claim 1, wherein the spring tensioner and the rotatable bayonet housing is a cam lever.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

(1) FIG. 1a is a cross section view, in a vertical plane, of a device according to the present invention;

(2) FIG. 1b is a cross section view, in a vertical plane, of a portion of a device according to the present invention;

(3) FIG. 2 is a cross section view, in a vertical plane, of a device according to the present invention;

(4) FIG. 3 is a cross section view, in a horizontal plane, of a device according to the present invention;

(5) FIG. 4 is a cross section view, in a vertical plane, of a device according to the present invention;

(6) FIG. 5 is a series of perspective views of the sequence of mounting and removing the sleeve of a device according to the present invention; and

(7) FIG. 6 is a cross section view, in a vertical plane, of a device according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIGS. 1a, 1b show a measuring device according to one particular embodiment of the invention, FIG. 1b being an enlargement of the upper region of FIG. 1a. Said figures show a device comprising:

(9) a lens (2) of the pyrometer, disposed in a lens holder (3) cooled by the passage of gas through the lateral channels (13) in the wall of the lens holder (3). The lateral channels (13) carry this gas under the protective window (12) and ensure constant sweeping, preventing any gas or dust from condensing on the protective window (12).

(10) a hollow bayonet rod (4) which has an end provided with two pins (7) and another end accommodating the lens holder (3) and the pyrometer lens (2). The intermediate part is disposed in the centre of a spring (11) supported by a locking cone (6) that is free to rotate about the bayonet rod (4),

(11) the spring (11) being held between the locking cone (6) and a ring (19) secured to the bayonet rod (4),

(12) the locking cone (6) having:

(13) 1. in its upper part, two opposite protuberances (20) that are parallel to the axis of the bayonet rod (4) and fixed with the aid of nuts to a double cam lever (9),

(14) 2. in its lower part, two opposite pegs (21) that are intended or configured to be accommodated in the notches (14) in the sleeve (8), the locking cone (6) pivoting, or configured to be pivoted: from a starting position in which the pegs (21) of the locking cone are in line with the notches (14) in the sleeve (8) and the pins (7) of the bayonet rod (4) are in line with the grooves (15), to a position angularly offset from the starting position, in which the pins (7) of the bayonet rod (4) are in the blocking portion (16) in a position offset from the grooves (15).

(15) 3. in its intermediate part, a lip that holds the spring (11). a double cam lever (9), secured to the locking cone (6) via the protuberances (20) of the cone, bearing against the ring (19). By pivoting the lever upwards, the locking cone (6) is lowered and releases the compression of the spring (11), which may be made of inconel in order to withstand the high use temperatures. a sleeve (8) made at least partially of refractory material, the composition of which is selected so as to reduce the production of gas at high temperatures. It may be made at least partially of alumina-graphite.

(16) a metal insert (10) accommodated in the upper part of the sleeve (8) and delimiting an inlet such as a frustoconical inlet for receiving the lower end of the bayonet rod (4).

(17) In the embodiment described above, the spring tensioner, also described as the tensioning means, and the locking component rotator, also described as means for rotating about the bayonet rod (4), are one and the same: the double cam lever (9) is used to turn the locking cone (6). FIG. 2 shows another embodiment: a nut (22)/bolt (23) system which is used for tensioning and is connected to two handles (24) for turning the locking cone (6).

(18) In FIG. 3, which shows the cross section through the sleeve on a horizontal plane, and in FIG. 4, which shows a cross section through the sleeve (8) on a vertical plane, two grooves (15) that pass vertically through the metal insert can be seen. In this way, these grooves allow the two pins (7) of the bayonet rod (4) to pass in. The pins (7) arrive under the metal insert (10), in the blocking portion (16) of the internal bore that has a cross section larger than the smallest cross section of the internal bore (17) and a sufficient height to allow the rotation of the pins (7) of the bayonet rod (4). The pins (7) can thus be rotated through a quarter turn, thereby fixing the bayonet rod (4).

(19) The grooves (15) are also used for evacuating gases emitted by the refractory material. The evacuation of the gases can be improved by creating a negative pressure in the sleeve (8) by way of a Venturi system for example. The gases will then be sucked out towards the outlet.

(20) FIG. 5 shows the sequence of mounting and removing the sleeve (8) (a to f): the operator inserts the sleeve (8) by bringing the pegs (21) of the locking cone (6) into correspondence with the notches (14) in the upper part of the sleeve (8), position (a). Then, the pins (7) of the bayonet rod (4), which are offset through a quarter turn with respect to the pegs (21) of the locking cone, pass into the grooves (15) in the metal insert. When the pegs (21) of the locking cone (6) are in the notches (14), the pins (7) of the bayonet rod (4) have passed beyond the metal insert and pass into the blocking portion (16) of the internal bore that has a cross section larger than the smallest cross section of the internal bore (17).

(21) By turning through a quarter turn (position b), the fixing of the bayonet rod (4) takes effect, and the operator can then release the sleeve (8). This rotational movement causes the locking cone (6) and thus the lever (9) to rotate through a quarter turn via the pegs (21) of the locking cone.

(22) The operator then vertically raises this lever (position c), thereby lowering the locking cone (6), which bears against the metal insert. By raising the lever, the spring (11) is partially relaxed, and is thus more flexible and can counter additional tensions which arise on account of the different coefficients of expansion of the refractory material and the metal.

(23) The measuring device is ready to be used. It then suffices to move the assembly above a tundish.

(24) Position (d) shows the device in operation, and the bottom of the sleeve (8) is hot.

(25) When it is subsequently necessary to replace the sleeve (8) made of refractory material, all that is required is to carry out the opposite movements of the lever (9). That is to say, lower the lever (position e) and then carry out a quarter turn (position f), thereby releasing the protective sleeve (8) into the tundish.

(26) A further subject of the invention is a method for measuring the temperature of a bath of molten metal, comprising the following steps of:

(27) providing a sleeve and an optical head as previously described:

(28) assembling the sleeve and the optical head by rotation of the sleeve, causing the rotation of the spring tensioner of the optical head, also described as the means for tensioning the spring of the optical head,

(29) decompressing the spring to form an assembly of the sleeve and optical head into a measuring device as previously described,

(30) positioning the assembly in the bath of molten metal, and

(31) measuring the temperature.

(32) The sleeve may be configured so that a single notch (14) is provided. The sleeve may consist of refractory material, consist essentially of refractory material, or be made only of refractory material. The bore in the inlet portion (18) spaced apart from the end of the sleeve may be frustoconical.

(33) It should be noted that the method for assembling the sleeve on the optical head can be applied to the assembling of a stopper rod on a fixing rod.

(34) The stopper rod thus has the following features: an open end provided with at least one notch, a closed end, a longitudinal axis, a main internal bore extending from the open end to the closed end along the longitudinal axis of the stopper rod, an inlet portion of the internal bore that is spaced apart from the open end of the stopper rod, the bore having grooves disposed along the lengthwise direction of the inlet portion; the grooves being angularly offset from said at least one notch in the open end, the grooves being designed or configured to guide the pins, of which there are three in certain embodiments, of a head of a bayonet rod into a portion for blocking the internal bore that has a cross section larger than the smallest cross section of the internal bore and a sufficient height to allow the rotation of the pins of the bayonet rod with respect to the stopper rod about the longitudinal axis of the stopper rod.

(35) Such a stopper rod can be used with a system for fixing the device described above, wherein the elements intended or configured to measure the temperature can optionally have been omitted.

(36) FIG. 6 shows a device according to claim 6. The vent tube is interlocked with the bayonet rod (4) and held with the aid of a screw. The cavity of the vent tube is flared in its lower part so as to avoid the situation in which a slight misalignment of the vent tube prevents the range of the pyrometer from reaching the bottom of the sleeve.

(37) Numerous modifications and variations of the present invention are possible. It is, therefore, to be understood that within the scope of the following claims, the invention may be practiced otherwise than as specifically described.

LIST OF REFERENCES

(38) 1. Inlet of the optical fibre and the measuring cables 2. Lens of the pyrometer 3. Lens holder 4. bayonet rod 5. Support bracket 6. Locking cone 7. Pins of the bayonet rod 8. Protective sleeve 9. Lever 10. Metal insert 11. Spring 12. Protective window 13. Gas inlet channel 14. Notches 15. Grooves 16. blocking portion of the internal bore 17. Main internal bore 18. Inlet portion of the internal bore (17) that is spaced apart from the open end of the sleeve (8) 19. Ring 20. Protuberance of the locking cone 21. Peg of the locking cone 22. Nut 23. Bolt 24. Handle 25. Vent tube