JPH0443207B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to steel mills, etc., in which plate thickness is measured in a plate rolling mill (plate mill) for rolling slabs (flat steel pieces) to make thick plates. The present invention relates to an improvement of a radiographic thickness gauge suitably used as a control plate thickness measuring instrument.

[Conventional technology]

A radiographic thickness gauge is a measuring device that measures the thickness of a plate by applying radiation from one side of the plate to be measured and measuring the energy of the radiation that has passed through the plate.

Such radiographic thickness gauges are susceptible to changes in the thickness due to reasons such as a decrease in radiation intensity over time due to the decay of the radiation source that generates the radiation, or deterioration over time of the detector for detecting the energy of transmitted radiation. There is a characteristic that the indication accuracy of the thickness dimension (also referred to as thickness indication linearity or scale accuracy) deteriorates over time.

Therefore, it is necessary to calibrate the indicating scale of a radiation thickness gauge by measuring a standard piece of known thickness once every two weeks to once a month. be. What is a standard thickness piece?
It is a plate made of a certain material and finished with an accurate thickness dimension, or a combination of multiple plates.

FIG. 5 is an explanatory diagram of the operation mode of a conventional radiographic thickness gauge for rolling control, and FIG.
It is a side view seen from the AA direction in the figure.

In these figures, 1 is a radiation source container, 2 is a detector, 3 is a plate to be measured, 4 is a thickness standard piece, 5 is a C frame, 6 is a wheel, 7 is a C frame drive motor, and 8 is a drive chain. , 9 is a transport roll,
10 is a sample stand, 11 is a rail, and 12 is a support for a transport roll.

In FIG. 5, when the thickness gauge is in the on-line position (right solid line position), the thickness of the plate material 3 to be measured is measured. By driving the motor 7 and rotating the wheel 6 via the chain 8, the thickness gauge moves on the rail 11 to the off-line position (left dashed line position), where it measures the thickness standard piece 4. The thickness scale is calibrated as a target.

Incidentally, it is known that the accuracy of the date display of such a radiation type thickness meter deteriorates when the relative positional relationship between the radiation source container 1, the detector 2, and the plate material to be measured 3 becomes out of order. Therefore, in the conventional thickness gauge, the source container 1 and the detector 2 are held together by using a C-shaped frame 5, as shown in FIG. Even when pulled out to an offline position, the relative positional relationship between them is not disturbed.

In this way, the radiation source container 1 and the detector 2 are pulled out to the off-line position by placing the thickness standard piece 4 at the exact same position (corresponding position) without interfering with the passage of the plate material 3 to be measured. This is so that the scale can be calibrated without stopping the rolling operation.

That is, as shown in FIG. 5, the C frame 5 is pulled out to the off-line position (the position indicated by the dashed line on the left), the sample stage 10 is assembled, and the thickness standard piece 4 is placed on the sample stage 10, thereby removing the radiation source container 1. , the rolling operation of the line is stopped while keeping the relative positional relationship between the detector 2 and the thickness standard piece 4 as the measuring object exactly the same as when measuring the plate material 3 in the online position. It is now possible to calibrate the scale of the thickness gauge.

By the way, in order to roll one slab into one plate and finish it, a plate rolling mill must pass the slab once between the two rolling rolls that make up the rolling mill, and then roll it again. The material is rolled between the rolls from the opposite direction, and then the material is rolled by reciprocating between the rolls several dozen times, thereby gradually finishing it into a plate with a predetermined thickness.

Therefore, at the beginning of rolling, the thickness of the plate is thick and the length is short, so the distance of reciprocating movement around the rolling mill (roll) is short, and at the end of rolling, the thickness of the plate becomes thinner until it reaches a predetermined thickness. As the dimensions approach, the length also increases, so the distance of reciprocating movement around the rolling mill (roll) also increases.

Therefore, in order to implement rolling control that measures the thickness of the plate from the beginning of rolling and adjusts the gap between the rolls accordingly, it is necessary to place the thickness gauge as close to the rolling mill as possible. If the thickness gauge is placed far away, the thickness of the plate will become considerably thinner as the number of rolling operations progresses, and the length will also increase accordingly.In this case, the thickness of the plate will be measured using the thickness gauge during the reciprocating process. Therefore, by the time it becomes possible to measure the plate thickness, the plate thickness may be thinner than the predetermined size, and the plate may become a defective product.

Alternatively, instead of measuring the thickness during the reciprocating process associated with the rolling operation, the thickness of the thick plate at the early stage of rolling, which is thick and short, is moved to a distant thickness gauge installation position, and the thickness is measured. It is also possible to adjust the gap, but in this case, the time required to measure the thickness becomes longer, which reduces the uniformity of the rolling mill and leads to higher product costs.

Under these circumstances, it is desirable to install the thickness gauge as close to the rolling mill as possible.

However, in reality, in steel works, etc., thickness gauges are used not only in the vicinity of the mill housing that houses the rolling mill, but also up to about 10 meters in front and behind the rolling mill along the flow direction. There is physically no place where the C frame 5 can be installed.

For this reason, in conventional thickness gauges, the C-frame was usually installed at a distant location about 10 meters or more away from the installation location of the rolling mill.

FIG. 7 is an overhead view showing the arrangement near the rolling mill to illustrate this situation.

In the figure, 13 is a mill housing housing a rolling mill (mill), 14 is a mill drive shaft, and 15 is a mill drive motor.

The upstream and downstream locations viewed from the mill housing 13 are symmetrical and identical. 16 is a turning roll, 17 is a side guide, 18 is a turning roll drive motor, 19 is a side guide drive mechanism, 20 is a transport roll drive motor, 9 is a transport roll, 12 is a support for the transport roll, 2 is a detector,
5 is a C frame.

The slab is moved in the upstream direction indicated by arrow Y (solid line) and the arrow
It is gradually rolled while reciprocating on the rolling path in the downstream direction indicated by Y' (broken line).

Here, the C frame 5 includes the mill housing 13
It will be seen that the support 12 is located between the side guide 17 and the support 12 at a position approximately 10 m downstream from the support 12.

As already explained, there are inconveniences caused by the physical circumstances in steelworks where thickness gauges have to be placed far from rolling mills, but in order to resolve these inconveniences,
Inside the mill housing 13, a thickness gauge closest to the plate mill is disposed near the rolling mill.

FIG. 8 is a schematic diagram showing the concept of such a thick plate mill nearest thickness gauge, and FIG. 9 is a schematic side view of FIG. 8 as viewed from the AA direction.

In these figures, 1 is a radiation source container, 21 is a radiation source container support part of the rolling mill structural elements, 2 is a detector, 22 is a detector support part of the rolling mill structural elements, 23 is a rolling roll, 24 is a back-up roll, 9 is a conveyor roll, 25 is a pass line (reference position) through which the rolled plate material is conveyed by the conveyor roll 9, and 26 is a mill housing.

That is, as seen in FIGS. 8 and 9, the radiation source container 1 and the detector 2 are installed inside the mill housing 26 using the structural elements (21, 22) of the rolling mill, and the pass line 25 Attach them so that they are facing each other. At this time, the radiation source container 1 and the detector 2
It doesn't matter which side is the top and which is the bottom.

If installed in this way, the thickness gauge consisting of the radiation source container 1 and the detector 2 can be installed in the immediate vicinity of the rolling mill.

However, in this case, the space inside the mill housing is such that it would be too tight to mount the thickness gauge in the immediate vicinity of the mill.
It is not possible to provide a mounting structure that allows the thickness gauge to be pulled out from an on-line position to an off-line position, as shown in FIG. This causes a problem in that the indication scale of the thickness gauge cannot be easily calibrated.

That is, as explained above, the relative positional relationship of the three components, the radiation source container, the detector, and the thickness standard piece, is determined by the relative positional relationship between the radiation source container, the detector, and the material to be rolled while the rolling line is in operation. Same as the positional relationship,
When attempting to calibrate the scale of a thickness gauge, in this case, one of the following methods (a) or (b) must be used.

(a) A method of calibrating the scale by placing a thickness standard piece on the conveyor roll 9 of the rolling line.

(b) After removing the radiation source container and the detector and transporting them to the outside of the mill housing, and reproducing the same positional relationship outside the mill housing as inside the mill housing, using a thickness standard piece, perform the procedure as described above. Calibrate the scale using the same method as before.
After completing the scale calibration, return both to the original mill housing and reinstall.

Therefore, first of all, when considering method (b) above, the source container weighs several hundred kilograms, the detector also weighs several hundred kilograms including the collimator, and the space inside the mill housing is limited. It can be said that method (b) above is extremely difficult to implement due to the extremely narrow scope and other reasons.

Next, when we examine method (a) above, we find that this method has the following drawbacks.

The first drawback is that the heat capacity of the rolling mill is extremely large, so even if the rolling mill is stopped, humans will have to measure the thickness for about 24 hours or more after the rolling operation has stopped, until the ambient temperature has dropped. It is not possible to get close to the installation location, so it is not possible to calibrate the scale. In other words, the time required to calibrate the scale is (24 hours + actual calibration time 30 minutes to 2 to 3 hours), so if you calibrate the scale once every two weeks to a month. , the operating rate of the line becomes considerably poor, resulting in large monetary losses.

The second drawback is that inside the mill housing, there is poor foothold for work, the space is small, there is no lighting, so it is dark, and the environment is hot, so in such a site, it is difficult to work with objects weighing several tens of kilograms. The point is that it is quite a difficult task to carry a standard thickness piece in and out.

The reason why you have to go in and out with the standard piece many times is because it is necessary to calibrate the scale for each thickness, so you have to replace the sample that becomes the standard piece, and you are exposed to radiation during the calibration. This is because it needs to be far away from the standard piece to avoid radiation exposure.

In this way, scale calibration work using method (a) above may expose workers to the risk of radiation exposure due to judgment errors caused by fatigue, and therefore, it is recommended that such work be performed regularly and constantly. It can be said that it is undesirable from the standpoint of occupational safety management to do so.

[Problem to be solved by the invention]

The present invention has been made in view of the conventional technical circumstances as described above, and the problem to be solved by the present invention is that a radiographic thickness gauge for rolling control is not installed in a rolling mill housing. The scale of the thickness gauge can be easily adjusted without having to take the thickness gauge out of the housing or requiring a person to enter the housing. It can be said that the purpose is to make calibration executable.

Accordingly, an object of the present invention is to provide a method for calibrating a radiographic thickness gauge for rolling control configured to enable the above-mentioned operations.

[Means to solve the problem]

In order to solve the above object, in the present invention,
A radiation line located within a housing that accommodates a thick plate rolling mill, adjacent to the rolling mill, and placed on one side of the conveyance path for rolled plates coming out of the rolling mill from above and below. As a method of calibrating the thickness scale of a radiographic thickness gauge for rolling control, which consists of a radiation source and a radiation detector placed on the other side, the method is to A thickness sample positioning mechanism is provided to sequentially position multiple thickness samples at any specified path position except for the intersecting portion, and a standard sample piece of known thickness is first placed along the radiation beam path along the sheet material conveyance path. The amount of radiation transmitted by the standard sample piece is measured, and the thickness scale is first calibrated based on the relationship between the thickness of the standard sample piece and the amount of radiation transmitted. After this primary calibration, the standard sample piece is is moved from the radiation beam path, a plurality of thickness samples are sequentially positioned by a positioning mechanism, and the amount of radiation transmitted by each thickness sample is measured to determine the primary calibration thickness of each thickness sample on the primary calibration scale. After that, at any time during the conveyance of the plate material, we sequentially position multiple thickness samples, measure the amount of radiation transmitted for each thickness sample, and calculate the thickness of each thickness sample using the primary calibration scale. The readings were compared to the primary calibration thickness of each thickness sample to provide a secondary calibration of the primary calibration scale.

[Effect]

By using the above technical means, the scale of the radiation thickness gauge is first calibrated using a standard sample piece of known thickness placed on the conveyance path of the plate material.
Following this primary calibration, a primary calibration thickness, which is the equivalent thickness on the primary calibration scale, for each of the multiple thickness samples located off the transport path of the plate material (e.g., housed in a radiation source container) Seeking the
After this, the thickness read value of each thickness sample on the conveyance path using the primary calibration scale is compared with the primary calibration thickness at any time during the conveyance of the plate material, and the primary calibration scale is secondarily calibrated. Calibration of a thickness gage by measuring multiple thickness samples on off-path locations is always related to calibration by measuring thickness standard pieces on the transport path, and calibration with thickness standard sample pieces on the transport path is A secondary calibration can easily be performed with a thickness sample located off the transport path without compromising the same accuracy.

Furthermore, as described above, by determining the equivalent thickness on the primary calibration scale of each thickness sample, the calibration method of the present invention can calculate the radiation of the standard sample piece using the standard sample piece and the thickness sample. Absorption Coefficient, Material/Density, and Thickness Even if the radiation absorption coefficient and material/density of the sample are different, there is no need to correct the difference again.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the main parts of a radiation source container used for calibrating a thickness gauge according to the present invention. That is, it is a longitudinal cross-sectional view showing the structure of the radiation source container 1 according to the present invention, which is arranged as shown in FIGS. 8 and 9.

FIG. 2 is a plan view of FIG. 1 viewed from the direction AA.

In these figures, 27 is the source capsule, 2
8 is a rotary source shutter, 28a is a shutter opening, 30 is a rotating plate, 29 is a support for the rotating plate 30, 31a to 31f are thickness samples, respectively.
32 is a collimator, 33 is a thickness sample drive motor, 34 is a reduction gear, 35 is a worm gear mechanism,
Reference numeral 36 indicates an arm; 37a and 37b indicate limit switches 38a and 38 which are respectively driven by strikers 38a and 38b as the arm 36 moves;
39a to 39d are limit switches for detecting rotational positions, 40a to 40c are strikers, 41 is a protrusion, 42 is a position mechanism, 43 is a measurement opening, 47 is a cap screw.

In FIG. 1, the radiation emitted from the source capsule 27 passes through the opening 28a of the rotary shutter 28, passes through the thickness sample 31a, and
The light is further narrowed down by the aperture 32a of the collimator 32 and irradiated toward an external detector.

Note that the rotary shutter 28 has shafts S1,
It is rotatably supported in the direction perpendicular to the plane of the paper with S2 as the center, and when rotated, the opening 2
8a takes a position perpendicular to the plane of the paper, and the radiation from the radiation source capsule 27 is blocked by the shutter 28 and does not reach the thickness sample 31a.

The thickness sample 31a is placed on a rotating plate 30 that is rotatable about an axis S3. Another thickness sample 31b is also placed on the rotary plate 30 at another position. The rotary plate 30 is placed on a disk-shaped support base 29 centered on an axis S3, and as described later, when driven by a motor 33, rotates stepwise around the axis S3. It's becoming like that.

That is, in FIG. 1, the thickness sample 31a is placed at a position where the radiation from the radiation source capsule 27 is transmitted, but the disk 30 is rotated step by step around the axis S3 by the motor 33. Thickness sample 31b can then replace 31a and be in a position to transmit radiation from source capsule 27.

This will be explained in more detail with reference to FIG. In FIG. 2, when the motor 33 rotates, its movement is transmitted to the worm gear mechanism 35 via the reducer 34, and when the arm 36 moves along the direction of arrow Y, the arm tip 36a is placed on the disk 30. It is designed to push the protrusion 41 provided.

When the arm 36 that has advanced in this manner is fully extended, the striker 38b that is integrally attached to the arm 36 switches the arm limit switch 37.
Touch b to operate this limit switch 3.
The rotation of the motor 33 is stopped by the signal from 7b, and then the motor 33 is driven in reverse. This causes the arm 36 to return in the opposite direction, and when it returns to the predetermined initial position, the striker 38b contacts and operates the arm limit switch 37a, and the motor 33 is stopped by a signal from the limit switch 37a. You can repeat the same thing as many times as you like.

On the rotary plate 30, six types of thickness samples 31a to 31f are arranged around the axis S3, and zero thickness samples, that is, the radiation irradiated to the plate material to be rolled when the rolling line is operating, are simply placed. An opening 43 for measurement is also provided to allow the sample to pass through. The thickness samples 31a to 31f and 43 are arranged at equal intervals at seven points on the circumference centering on the axis S3, and the thickness samples 31a to 31f and 43 are arranged at equal intervals at seven points on the circumference centering on the axis S3.
The projections 41 to be driven by the shaft 6a are also arranged at seven points on the circumference centered on the axis S3 at equal intervals.

The rotational position of the rotary plate 30 (in other words, which thickness sample is in the position to receive the radiation from the source capsule 27) is mounted on the rotary plate 30 and is integral with the rotary plate 30. Strikers 40a, 40b, 40c that move
However, depending on the rotational position of the rotary plate 30, the rotational position detection limit switches 39a, 39b, 39c,
Since one of the limit switches 39d is driven to operate, it can be known from a remote location using a code consisting of a combination of ON and OFF outputs of each limit switch.

In addition, each of the thickness samples 31a to 31f and the measurement opening 43 are aligned with the axis S each time the arm tip 36a pushes the protrusion 41 once.
However, if the source capsule 27 is not positioned correctly (or misaligned) as a result of being driven, the radiation source capsule 27
It is not possible to properly transmit radiation from the
Calibration results are not reproducible. Therefore, it is necessary to position correctly, and the details of the positioning mechanism 42 for this purpose will be explained below.

FIG. 3A is a sectional view of the positioning mechanism 42 in the positioning state, and FIG. 3B is a sectional view of the positioning mechanism 42.
FIG. 3 is a cross-sectional view when the device is in a state on the way to a positioning state.

In these figures, 29 is a support base, 30 is a rotary plate placed on it, 44 is a coil spring, 45 is a steel ball, 46 is a conical groove formed in the support base 29, and 47 is a holding screw. The positioning mechanism 42 is made up of these components.

That is, a steel ball 45 and a coil spring 44 are inserted into a hole M made in the rotating plate 30, a retaining screw 47 is screwed in, and the elasticity of the spring 44 causes the steel ball 4 to
5 is pressed against the support stand 29. conical groove 4
6 are at seven locations on the circumference centered on the axis S3, which is the locus of movement of the positioning mechanism 42 on the support base 29.
They are placed at equal intervals.

When in the positioning state, each steel ball 45 in the three positioning mechanisms 42 is in the seven grooves 4.
As shown in FIG. 3A, the spring 44 presses and fits into any three of the 6.

Now, the specific example of the positioning mechanism 42 has been understood.

I mentioned the following earlier. That is,
The accuracy of the scale indication of a radiation thickness gauge becomes incorrect if the relative positional relationship between the radiation source container, the detector, and the plate to be measured goes out of order. It was stated that the relative positional relationship between the sample and the thickness sample needs to be kept the same as that during online operation.

Examining the main parts of the radiation source container shown in FIGS. 1 and 2 from this point of view, we find that in FIG. On the other hand, when the rolling operation is online, as shown in Fig. 8, the plate material to be measured is
Since it is transported outside the radiation source container 1 by the transport roll 9, the relative positional relationship is different,
It can be seen that even if the scale is calibrated using the actual thickness of the thickness sample, the scale will not be valid as it is during online rolling operation.

Therefore, as a countermeasure for this, the following can be done. In short, it is sufficient to replace the thickness of each thickness sample shown as 31a to 31f in Fig. 1 with the thickness of the equivalent thickness standard piece on the conveyor roll. When the detector is first installed near the rolling mill, when the rolling line is stopped, or when the detector is replaced for maintenance reasons,
Taking advantage of the suspension of the rolling line during the replacement, a thickness standard piece separate from the thickness samples shown as 31a to 31f in FIG. 1, that is, a thickness standard piece shown as 4 in FIG. 5, was prepared. , the amount of radiation attenuation when the plate material to be measured is placed on the transport roll being transported is compared with the amount of radiation attenuation due to the thickness samples in the radiation source container shown as 31a to 31f in FIG. Calibrate the scale by replacing the thicknesses of the thickness samples shown as 31a to 31f in the figure as scale calibration reference values with the thickness of the thickness standard piece (Figure 5, 4) with equivalent radiation attenuation on the conveyor roll. If you do this, you will get exactly the same result as if you calibrated the scale using the standard piece on the conveyor roll.

FIG. 4 is a schematic diagram showing an example of a usage mode of the radiographic thickness gauge for rolling control according to the present invention.

In the figure, 1 is a radiation source container, 31 is a thickness sample, 2 is a detector, 50 is a scintillation counter, 51 is a push button switch, 48 is a computer for the thickness gauge, 49 is a rotation drive for the thickness sample, etc. 52 is a constant temperature bath, 53 is a pump, 54 is a fluid tank, 55 is a heater, 56 is a cooler, 57 is a sensor for the fluid temperature in the tank, 58 is a thermometer that measures the temperature of the thickness sample, It is.

The operation when calibrating the indicator scale of the thickness gauge will be explained.

The programmable controller 49 is configured as a subordinate system to the thickness gauge computer 48. Now, when the push button switch 51 is operated, the computer 48 instructs the controller 49 to perform an operation for scale calibration.

The controller 49 selects a timing when there is no plate material to be rolled between the radiation source container 1 and the detector 2, and sequentially moves the plurality of thickness samples contained in the radiation source container 1 to the path position of the radiation beam. I drive it against it and position it. That is, starting with a sample of zero thickness, a sample with a first thickness, a sample with a second thickness, and so on.
Each thickness sample is driven and positioned in a predetermined order (according to a programmed schedule).

Since the controller stores the thickness dimension of each sample in advance, the controller stores the thickness dimension actually measured via the detector 2, counter 50, and computer 48 for each sample positioned as described above. Multi-point scale calibration can be automatically performed by comparing the dimensions one after another.

When the scale calibration is completed, the controller 49 automatically returns the zero-thickness sample to the pass position, returns the plate material to be rolled to a state in which the thickness can be measured, and displays or notifies the outside.

In addition, in light of the well-known fact that short-period noise that occurs when actually measuring sample thickness during scale calibration decreases in inverse proportion to the square root of the time required for measurement, it is important to note that the required measurement time should be long enough to match the required scale calibration accuracy. , predetermined for each thickness sample,
By programming and performing scale calibration,
The time required for scale calibration can be minimized while ensuring the necessary calibration accuracy.

Next, we will examine the indication error of the scale due to the ambient temperature of the thickness sample.

Now, as an example, a sample with a plate thickness of 50 mm is
Temperature change of 40℃ due to summer, winter or heat from rolling line
If we estimate the degree of indication error caused by this, it is as follows for a thickness gauge with a cold measurement indication.

50mm x 40℃ x 2 [coefficient for cold dimensions, 3 for hot dimensions] x linear expansion coefficient 1.5 x 10 ^-5 = 0.06mm,
In other words, an indication error of approximately 60 μm will occur.

Since the required accuracy for calibrating the scale of a thickness gauge is about 10 to 30 μm, this is a very problematic number. Therefore, as shown in FIG. 4, a temperature sensor 57, a heater 55, and a cooler 56 are attached to the tank 54, and the constant temperature fluid is circulated around the constant temperature bath 52 surrounding the sample section using the pump 53. It is recommended to maintain the accuracy of scale calibration by keeping the temperature of the sample constant.

Furthermore, as shown in FIG. 4, temperature information about the sample obtained by placing a thermometer 58 in the built-in part of the thickness sample can be input into the computer 48 to accurately compensate for the effects of temperature changes on the sample. can.

That is, a thermometer (temperature measurement sensor) is attached to the part where the thickness samples are stored or to each sample itself, so that the temperature measured by the temperature sensor can be known remotely from the outside. By determining the relationship between "temperature vs. radiation dose" or "temperature vs. thickness indication" theoretically or experimentally in advance, the radiation dose or thickness indication at the above measurement temperature can be calculated at the reference temperature for scale calibration. This makes it possible to compensate for thickness indication errors due to temperature changes in the built-in sample during scale calibration.
This is done by a computer.

Alternatively, the measured temperature information is imported into a remote external programmable controller 49,
The controller is configured as a subordinate system of the computer 48. Required data is stored in advance in this controller, and the controller automatically performs the required conversion using this data and the temperature information taken into the controller. Alternatively, the scale calibration may be performed with a high degree of accuracy, thereby realizing highly accurate scale calibration.

〔Effect of the invention〕

As explained above, according to the present invention, while the radiographic thickness gauge for rolling control is installed in the mill housing in the immediate vicinity of the rolling mill,
It is not necessary to take the thickness gauge out of the housing, nor does it require a person to enter the housing, and the thickness standard sample can be easily and automatically transferred from a remote location to the conveyance path of the plate material. There is an advantage that the scale calibration of the thickness gauge can be performed with the same accuracy as when calibrating the thickness gauge after installation.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the main parts of the radiation source container used for calibrating the thickness gauge according to the present invention, Fig. 2 is a plan view seen from the A-A direction in Fig. 1, and Fig. 3A is the positioning mechanism. FIG. 3B is a sectional view when the positioning mechanism is in the positioning state, and FIG. 4 is a sectional view showing how the radiographic thickness gauge according to the present invention is used. A schematic diagram showing an example, FIG. 5 is an explanatory diagram of the operating state of a conventional radiographic thickness gauge for rolling control, FIG. 6 is a side view seen from the A-A direction in FIG. 5, and FIG. An overhead view showing the conventional arrangement near the rolling mill, Fig. 8 is a schematic diagram showing the concept of the conventional thick plate mill nearest thickness gauge, Fig. 9 is a side view seen from the A-A direction in Fig. 8, It is. Explanation of symbols, 1... Source container, 2... Detector, 3
...Plate material to be measured, 4...Thickness standard piece, 5...
C frame, 6...Wheel, 7...C frame drive motor, 8...Drive chain, 9...Transport roll, 10...Sample stand, 11...Rail,
12... Conveyance roll support, 13... Mill housing, 14... Mill drive shaft, 15...
Mill drive motor, 16...Swivel roll, 1
7...Side guide, 18...Swivel roll drive motor, 19...Side guide drive mechanism, 20...Transportation roll drive motor, 21...Radiation source container support section, 22...Detector support section, 23... …
Roll, 24...Backup roll, 25
...Pass line, 26...Mil housing, 27
...Radiation source capsule, 28...Rotary type radiation source shutter, 28a...Shutter opening, 29...Rotating plate support, 30...Rotating plate, 31a to 31f
... Thickness sample, 32 ... Collimator, 32a
...Aperture, 33...Thickness sample drive motor,
34... Attenuator, 35... Worm gear mechanism, 3
6...Arm, 36a...Arm tip, 37
a, 37b... Limit switch for arm, 38
a, 38b... Striker, 39a to 39d...
Limit switch for rotational position detection, 40a-40
c... Striker, 41... Protrusion, 42... Positioning mechanism, 43... Measuring opening, 44... Coil spring, 45... Steel ball, 46... Conical groove, 47... Holding screw , 48...computer, 49...programmable controller, 50
... Scintillation counter, 51 ... Push button switch, 52 ... Constant temperature bath, 53 ... Pump, 5
4... Tank, 55... Heater, 56... Cooler, 57... Tank internal temperature sensor, 58... Sample thermometer.

Claims (1)

[Claims] 1. Located within a housing that accommodates a thick plate rolling mill, located adjacent to the rolling mill, and sandwiching the conveyance path for rolled plate materials coming out of the rolling mill from above and below. A method for calibrating the thickness scale of a radiographic thickness gauge for rolling control comprising a radiation source disposed on one side and a radiation detector disposed on the other side, comprising: a radiation beam extending from the radiation source to the detector; In the pass, a thickness sample positioning mechanism is provided to sequentially position a plurality of thickness samples at arbitrary specific pass positions other than the portion intersecting with the conveyance path of the plate material, and first, a standard with known thickness is provided. A sample piece is placed at a portion where the radiation beam path intersects with the transport path of the plate material, the amount of radiation transmitted by the standard sample piece is measured, and the thickness is determined from the relationship between the thickness of the standard sample piece and the amount of radiation transmitted. Perform a primary calibration of the scale, and after this primary calibration, move the standard sample piece from the radiation beam path, and
Sequentially positioning the plurality of thickness samples by the positioning mechanism, measuring the amount of radiation transmission for each thickness sample to determine the primary calibration thickness of each thickness sample on the primary calibration scale, and thereafter at any time. , sequentially position the plurality of thickness samples, measure the amount of radiation transmission for each thickness sample, and measure the thickness reading of each thickness sample according to the primary calibration scale with respect to the primary calibration scale of each thickness sample. A method for calibrating a radiographic thickness gauge for rolling control, characterized in that the primary calibration scale is secondarily calibrated by comparing it with a calibrated thickness.