JPS6055009B2 - Radiation thermometer for wire rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation thermometer for wire rods, and in particular, uses a light receiving element having sensitivity unevenness in the axial direction of the wire rod as an object to be measured and in the direction perpendicular to the measurement optical axis. The present invention relates to an improvement in a radiation thermometer for wires using a wire diameter correction method that measures the temperature of the wire through a field of view formed by a rectangular target placed between an element and the wire.

In recent years, temperature control has become more important in order to improve the quality control of wire rods. In these temperature measurements, a special measurement method is used because the diameter of the object to be measured is as small as 5.5 to 19 wg. One of them, as shown in Figure 1, is
A lens 13 and a rectangular mask 14 forming a rectangular target are arranged between the light receiving element 10 and the wire 12, and the so-called wire diameter is measured in a rectangular target field of a fixed area formed by the rectangular mask 14 at a position where the wire 12 passes. There is a correction method. In this wire diameter correction method, if the wire diameter of the wire 12 changes, the area ratio occupied by the wire 12 changes, so this is converted to the output when the entire field of view is occupied by wires of the same temperature. A wire diameter corrector 16 is used. According to this wire diameter correction type radiation thermometer, compared to the so-called scanning method in which scanning is performed in a field of view with a measurement diameter smaller than the minimum diameter of the wire, a movable part for scanning is not required, and the wire 12 is It has the characteristic that the measured value is representative because it measures the average temperature of half the circumference. However, in this wire diameter correction type radiation thermometer, the wire 12
The position at which the radiant energy is focused on the surface of the light receiving element 10 is determined by the position of the wire 12 within the measurement field of view.
That is, as shown in FIGS. 1 and 2, when the position perpendicular to the axial direction of the wire in FIG. 1 is at position A, the image is formed at position B on the surface of the light receiving element. On the other hand, when the position perpendicular to the optical axis is at the A'' position, the light receiving element 1
0 surface, the image will be formed at position B''. Therefore, if the sensitivities at positions B and B'' on the light receiving element 10 are the same, there will be no variation in measured values due to sensitivity. However, in reality, it is impossible to obtain uniform sensitivity due to the manufacturing process of the light receiving element 10, so there is a problem that the measured values vary due to positional fluctuations in the direction perpendicular to the axial direction of the wire 12. The light-receiving element 10 was made of silicon, and at a measurement distance of 600T!n, a wire radiation thermometer with a square field of view of 28TfgR on a side and a measurement range of 600 to 1100°C was used.The wire diameter was 8T1r. !!FIG. 3 shows the relationship between the wire position and the measured value when measuring a wire with a t1 temperature of 900°C.

In Figure 3, since the field of view is square, the position of the wire is changed in five steps in two directions, the x direction and the Y direction, and the measured value at each position is This shows whether there is such a relationship. As is clear from these measured values, it is difficult to improve the measurement accuracy of wire radiation thermometers using the wire diameter correction method unless the variation in measured values due to uneven sensitivity on the surface of the light receiving element is reduced. One thing is clear.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and even when using a light receiving element that has sensitivity unevenness in the axial direction of the wire being measured and in the direction perpendicular to the measurement optical axis, the measured value remains unchanged. It is an object of the present invention to provide a radiation thermometer for wire rods that does not fluctuate due to positional fluctuations in the axial direction of the wire rod and in the direction perpendicular to the measurement optical axis.

The present invention uses a light-receiving element having sensitivity unevenness in the axial direction of a wire rod as an object to be measured and in a direction perpendicular to the measurement optical axis, and a rectangular target field of view formed by a rectangular mask placed between the light-receiving element and the wire rod. In a radiation thermometer for wire rods using a wire diameter correction method that measures the temperature of the wire rod through the wire, a part of the field of view of the rectangular target is shielded, and at least the wire axis direction of the light receiving element and the direction perpendicular to the measurement optical axis are The above object is achieved by providing a shielding means for correcting sensitivity unevenness.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The first embodiment of the present invention, as shown in FIGS. 4 and 5,
A phosphor bronze shielding plate 20 whose one end surface is a stay portion 20a having a substantially inverted L shape is fixed to the end side wall 14a of the rectangular mask 14 with a set screw 22, and a rectangular mask is attached to the opposite side of the set screw 22. An adjustment screw 24 screwed into the end side wall 14a of the shield plate 20 is provided, and by changing the insertion depth of the adjustment screw 24, the shielding position and shielding amount of the shielding plate 20 with respect to the rectangular target field of view can be changed. It was made by The amount of shielding of the surface of the light receiving element 10 by the shielding plate 20 in this embodiment is determined as follows.

That is, it is now assumed that the relationship between the wire position and the sensitivity of the surface of the light-receiving element 10, determined as shown in FIG. 3, shows a distribution as shown in FIG. 6. In FIG. 6, the numbers indicate relative values of sensitivity, and the larger the number, the greater the sensitivity. In a light receiving element having a surface sensitivity distribution as shown in Fig. 6, in order to keep the measured value constant against positional changes in the wire axis direction and the x direction, which is a direction perpendicular to the measurement optical axis, it is necessary to It is necessary that the sensitivity in the Y direction at the position is the same. Now Y5
Considering the case where the sensitivity in the Y direction is made the same by shielding only the Y direction, the sum of the sensitivities from Y1 to Y4 in the X1 column is 50, . The sum of the sensitivities from Y1 to Y in the X2 column is 5.The sum of the sensitivities from Yl to η in the AX3 column is 5.The sum of the sensitivities from Y1 to η in the X4 column is 3.X5
Since the sum of the sensitivities from Y1 to Y4 in fiil is 30, the X4 row and X5, which have low sensitivity, are not shielded, and the sum of the sensitivities from Y1 to Y5 from X1 to the island group is 5
It is necessary to shield it so that it is equal to 7. This amount of shielding is calculated as shown in the following equation. From the above calculation results,
If the portion Y5 at each position in the x direction is shielded as shown by the shaded area C shown in FIG. 7, the sensitivity at each position in the x direction becomes the same.

In this embodiment, since the shielding plate 20 having a linear end face is used as the shielding means, the actual shielding position is shown by the shaded area D in FIG. In the case of shielding with a shielding plate, the sensitivity of each part of the light receiving element 10 corresponding to FIG. 6 is as shown in FIG. 8.
In this example, the sensitivity of the X1 column is 50, and the sensitivity of the X2 column is 60. Sensitivity of island chain is 62, sensitivity of X4 is 46sX
5y! The sensitivity of 1 is 52, and the sensitivity ratio of each column in the x direction is 1.1:1.3:1.3:1:1:1.1. On the other hand, the sensitivity ratio in each row in the x direction before shielding is 81:86:81:57:57=1.6
:1.7:1.6:1:1, which clearly shows a considerable improvement. A second embodiment of the present invention is shown in FIGS. 9 and 10. In this embodiment, the shielding means is a large number of shielding rods 30 arranged in parallel in the X direction, and the amount of shielding of each can be adjusted independently of each other. The second embodiment differs from the first embodiment in this respect.

The other points are the same as those of the first embodiment, so the explanation will be omitted. In this embodiment, unlike the case where a shielding plate with straight end faces is used as in the first embodiment,
Since detailed shielding can be performed according to the required shielding amount calculated from the surface sensitivity distribution of the light-receiving element, variations in the sensitivity distribution in the x direction can be made more uniform.

In each of the above embodiments, the sensitivity of the light receiving element was made uniform only by the shielding means disposed between the light receiving element 10 and the wire 12, but as shown in FIG. The wire is divided into a large number of parts in the axial direction and the direction perpendicular to the measurement optical axis, and variable resistors 32a to 32n are connected to each of the divided light receiving elements 10a to 10n, and the amount of attenuation by the variable resistors is calculated as the surface sensitivity. It is also possible to reduce the sensitivity unevenness on the output side of the light receiving element 10 by changing it according to the distribution, thereby further eliminating the sensitivity unevenness.

As explained above, the present invention is an object to be measured. Using a light-receiving element that has sensitivity unevenness in the axial direction of the wire and in the direction perpendicular to the measurement optical axis, the temperature of the wire is measured through a rectangular target field of view formed by a rectangular mask placed between the light-receiving element and the wire. In the radiation thermometer for wire rods using the wire diameter correction method, the rectangular shape described above. A shielding means for shielding a part of the target field of view and correcting sensitivity unevenness of the light receiving element in at least the axial direction of the wire and in the direction perpendicular to the measurement optical axis is provided, and Since measurement errors caused by positional fluctuations are reduced, the temperature measurement accuracy of the radiation thermometer is significantly improved compared to conventional ones. Therefore, it is now possible to control the temperature of the wire more strictly than before.
It has the excellent effect of significantly improving the quality of the wire rod. According to the inventor's experiments, in a conventional radiation thermometer that does not use a shielding means, the variation in measured temperature was about 5 degrees Celsius, whereas the radiation thermometer for wire rods using a shielding plate as shown in the first embodiment According to the thermometer, this variation could be reduced to about 2°C.

[Brief explanation of the drawing]

FIG. 1 is a route diagram showing the configuration of a conventional radiation thermometer for wire rods using the wire diameter correction method, FIG. 2 is a route diagram showing the relationship between the light-receiving element and the wire rod position, and FIG. FIG. 4 is a diagram showing the relationship between wire position and temperature measurement error in a radiation thermometer for wire rods, and FIG. The figure is also a side view, Figure 6 is a line diagram showing an example of the surface sensitivity distribution of the light receiving element, and Figure 7 shows the state in which the light receiving element as shown in Figure 6 is shielded with a shielding plate. Diagram, Figure 8 is the 7th
As shown in the figure, FIG. 9 is a diagram showing the sensitivity distribution in the shielded light-receiving element.
0 is a side view, and FIG. 11 is a diagram showing an example of application in which the sensitivity distribution is adjusted also on the output side of the light receiving element. 10... Light receiving element, 12... Wire rod, 1
4... Rectangular mask, 20... Shielding plate, 30... Shielding rod.

Claims (1)

[Claims] 1 Using a light-receiving element that has sensitivity unevenness in the axial direction of the wire to be measured and in the direction perpendicular to the measurement optical axis, through a rectangular target field of view formed by a rectangular mask placed between the light-receiving element and the wire. In a wire radiation thermometer using a wire diameter correction method that measures the temperature of a wire, a part of the rectangular target field of view is shielded to reduce sensitivity unevenness of the light receiving element at least in the wire axis direction and in the direction perpendicular to the measurement optical axis. A radiation thermometer for wire rods, characterized in that a correction shielding means is provided to reduce measurement errors caused by positional fluctuations in the axial direction of the wire rod and in the direction perpendicular to the measurement optical axis.