JPH044376B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a continuous heating system in which the position of a heating part that continuously heats a long object to be heated and the position of a sensor that measures the temperature of the heated object are shifted from each other. The present invention relates to a control device for a device.

For example, in a pipe having a welded part such as an electric resistance welded pipe, since the material of the welded part is hardened, it is necessary to perform an annealing treatment to facilitate normal temperature processing.

Such annealing treatment is performed as shown in Fig. 1.
This is performed by high-frequency heating while continuously passing the electric resistance welded tube 1 through a coil 2 to which high-frequency power is applied from a high-frequency power source 3.

However, in such an annealing process,
Good quality cannot be obtained unless it is baked at the optimum temperature. Moreover, even if one tries to measure the temperature during annealing, the high-frequency coil 2 gets in the way and it is extremely difficult to measure the annealing temperature directly below the high-frequency coil 2. Therefore, the sensor 14 is installed near the exit of the high-frequency coil 2. , only the temperature at the outlet can be measured.

In this way, the sensor 1 is placed at the outlet of the high frequency coil 2.
4 and an automatic control system that controls the high-frequency power supply 3 so that the temperature output of the sensor 14 remains constant, the heating section directly under the high-frequency coil 2 and the temperature measurement section of the sensor 14 may deviate by the distance. As a result, there was a problem in that the automatic control system caused hunting at intervals of the time t required to travel this distance D.

In order to prevent such hunting, it is possible to increase the time constant of the feedback loop of the automatic control system, but increasing the time constant deteriorates the response, which is not preferable.

Therefore, the control device of the present invention was devised to solve such problems, and will be described in detail below with reference to the drawings.

As shown in FIG. 2, this embodiment is applied to an annealing device equipped with an object to be heated such as an electric resistance welded tube 1, a heating section consisting of a high frequency power source 3 and a coil 2, and a sensor such as an optical thermometer 4. Let's discuss an example.

The analog output T of the optical thermometer 4 provided near the exit of the high-frequency coil 2 is led to the comparison circuit 5 together with the analog output S of the temperature setting device 6. The deviations S to T are converted into digital values by the A/D converter 7.
Converted to S _D ~ T _D. Further, N shift registers 8 and a digital addition/subtraction circuit 9 that adds and subtracts the N-bit digital value R _D output from the shift registers 8 and the digital output (S _D to T _D ) of the A/D converter 7 are provided. , the N-bit digital output (R _D ±S _D ~ T _D ) obtained from this digital addition/subtraction circuit 9 is
A circuit 11 that applies voltage to each input terminal of the shift registers 8, and a D/A converter 10 that converts the N-bit digital output of the digital addition/subtraction circuit 9 into an analog output P and leads it to the control input of the high frequency power supply 3. We are prepared.

On the other hand, a pulse generator 12 is provided which generates a pulse output every time the electric resistance welded tube 1 moves a certain distance and is used as a shift pulse signal source for the shift register 8.

The pulse repetition frequency of this pulse generator 12 and the number of stages of the shift register 8 are
The digital value applied to the input terminal of the shift register 8 is shifted to its output terminal while traveling a distance D from the part A surrounded by the high-frequency coil 2 to the field of view B of the optical thermometer 4. has been selected.

Next, the operation of the control device of the present invention configured as above will be explained.

At the start of operation, all the stored contents of the shift register 8 are zero, and the surface temperature of the ERW tube 1 within the field of view B of the optical thermometer 4 is low, so the output voltage T of the optical thermometer 4 is low. This is different from the output voltage S of the temperature setting device 6 which is set to the annealing temperature, and is compared by the comparator circuit 5 to obtain the difference voltage S to T between the two. This differential voltage is converted into a digital value S _D ~
It is converted into T _D and added to or subtracted from the digital output R _D of the shift register 8 in the digital addition/subtraction circuit 9 .

At this time, the output voltage T of the optical thermometer 4 is almost zero, and the digital output of the shift register 8
Since R _D is also almost zero, the output of A/D converter 7
S _D to T _D are almost S _D , and are guided as they are to the D/A converter 10 without any addition or subtraction in the digital addition/subtraction circuit 9, and are analog output (P, in this case P=S ) is applied to the high frequency power supply 3, and the output of the high frequency power supply 3 is controlled based on the analog output, and the controlled high frequency output is applied to the part A of the ERW pipe 1 surrounded by the coil 2.
is heated.

On the other hand, the digital output (R _D ±S _D ~T _D ) of the digital adder/subtractor circuit 9 is fed back to the input terminal of the shift register 8, and is sequentially shifted by the shift pulse signal from the pulse generator 12, and is then input to the coil. The heated part A at the position surrounded by 2 is at a distance D
When it reaches the field of view B of the optical thermometer 4, it appears at the output terminal of the shift register 8.

When the heated portion A in the position surrounded by the coil 2 reaches the field of view B of the optical thermometer 4, the output voltage T of the optical thermometer 4 increases.

The deviation S to T between the output voltage T of the optical thermometer 4 and the output voltage S of the temperature setting device 6 is detected by an A/D converter 7.
After converting it into digital values S _D ~ T _D , it is led to the addition/subtraction circuit 9 along with the output R _D of the shift register 8.
By adding or subtracting the output S _D to _{T D} of the A/D converter 7 to the heating control amount R D stored in the shift register 8, a correction of S _D to T _D is added to the control amount P _D. ,
This corrected control amount (R _D ±S _D ~ T _D ) is fed back to the input terminal of the shift register 8, and the D/
After converting it into an analog value P with the A converter 10, the high frequency power source 3 is applied, and the output of the high frequency power source 3 is controlled based on this corrected analog amount, and the coil 2 is surrounded by the controlled high frequency output. Part A is heated.

Each time the portion A heated in this way advances by a distance D and reaches the field of view B of the optical thermometer 4, the control amount at the time of heating is outputted to the output terminal of the shift register 8, and the optical thermometer 4 Find the deviation S to T between the temperature when reaching field of view B and the set temperature,
When a deviation occurs, the output of the shift register 8 is corrected according to this deviation (R _D ±S _D ~ T _D )
The output of the high frequency power supply 3 is controlled by this.

If the period during which the ERW tube 1 advances from the part A surrounded by the coil 2 to the field of view B of the optical thermometer 4 is defined as one cycle, each control amount during heating for each phase is controlled by the shift register 8. The output is sequentially shifted one cycle at a time, and control is performed by making the temperature in the field of view B of the optical thermometer 4 correspond to the control amount during heating.

Note that the temperature measured in the field of view B of the optical thermometer 4 will be slightly lower than the temperature in the area B surrounded by the high-frequency coil 2, but this decrease can be obtained empirically and corrected in advance. be.

In the embodiment described above, N shift range registers 8 are used to shift N-bit digital values in parallel, but by using means for converting digital signals from serial to parallel, a single shift range register 8 is used. A shift register may be used to serially shift the N-bit digital value.

Although the control device of the present invention has been explained by taking an example of annealing the electric resistance welded pipe 1, it may also be applied to the position of the heating part, such as continuous heating of various long materials such as cotton material, pipe material, bar material, etc. Excellent effects can be achieved by applying the present invention to various heating devices in which the sensors for measuring temperature and temperature are disposed at different positions.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a conventional continuous heating device, and FIG. 2 is a block diagram showing an embodiment of a control device for a continuous heating device according to the present invention. 1... Heated object, 2... High frequency coil, 3...
High frequency power supply, 4...Sensor (optical thermometer), 5
... Comparison circuit, 6 ... Setting device, 7 ... A/D converter, 8 ... Shift register, 9 ... Addition/subtraction circuit,
10...D/A converter, 12...Pulse generator.

Claims (1)

[Claims] 1. A heating section that continuously heats a long object to be heated;
A long object to be heated is continuously heated, which is equipped with a sensor that is located at a distance from the heating section and measures the temperature of the object to be heated, and a control means that automatically controls the output of the heating section based on the output of the sensor. In a continuous heating device that heats the long object to be heated, the device includes a pulse generator that generates a pulse output every time the long object to be heated moves a certain distance, and a control amount for each part when heating the long object to be heated. a shift register in which each of the controlled variables is shifted by the pulse output of the pulse generator so that the corresponding controlled variable is sequentially input each time each heated portion reaches the sensor; and a correction means for correcting the output of the shift register based on the deviation between the temperature obtained by the sensor and the set value, and applying the corrected control amount to the input of the shift register and the input of the control means. 1. A control device for a continuous heating device, comprising: a circuit for guiding; and a control device for a continuous heating device.