JPH0517289B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a continuous heating system in which the position of a heating section over a certain length that is continuously heated and the position of a temperature measuring device that determines the heating result are disposed apart from each other. The present invention relates to a control device for a heating device.

For example, in a pipe having a welded part such as an electric resistance welded pipe, the material of the welded part is hardened, so annealing is necessary to facilitate room-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 annealing is performed at the optimum temperature. Moreover, even if you try to measure the temperature during annealing, the high-frequency coil 2 gets in the way, making it extremely difficult to measure the annealing temperature directly below the high-frequency coil 2. provided, only the temperature at the outlet can be measured.

In this way, even if the temperature measurement device 14 is provided at the outlet of the high frequency coil 2 and an automatic control system is provided to control the high frequency power source 3 so that the temperature output of the temperature measurement device 14 maintains a constant value, the temperature measurement device 14 directly below the high frequency coil 2 Since the heating section of the temperature measuring device 14 and the temperature measuring section of the temperature measuring device 14 are deviated by a distance d, there is a problem in that the automatic control system causes hunting depending on the period of time 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 these problems, and will be described in detail below with reference to the drawings.

As shown in Fig. 2, it 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 temperature measuring device such as an optical thermometer 4. An example will be described below.

The analog output of the optical thermometer 4 installed near the outlet of the high-frequency coil 2 is led to the comparison circuit 5 together with the analog output of the temperature setting device 6, and the deviation between the two analog outputs obtained by the comparison circuit 5 is , are led to one input terminal of the addition/subtraction circuit 7.

The output of the high frequency power supply 3 corresponding to the amount of heat input, that is, the output of the integrating circuit 8 which generates an output proportional to the product of the voltage E and the current I, is applied to the other input terminal of the addition/subtraction circuit 7. Furthermore, the integrated output of the power integrator 13 is applied to another input terminal, and the output of this addition/subtraction circuit 7 is led to a control input terminal of the high frequency power source 3.

The output of the integration circuit 8 is led to an A/D converter 9 where it is converted into an 8-bit digital value, and then sent to eight sister registers 2 for each bit with a different weight.
It is led to serial input terminals 1 to 28.

Each shift register 21-28 has 16 stages, each stage is provided with a parallel output terminal, and each parallel output terminal is connected to each input terminal of multiplexers 31-38, respectively.

Each of these multiplexers 31 to 38 selects the input signals applied to the 16 input terminals according to the binary address inputs A, B, C, and D, and guides the selected signals to the respective output terminals.

On the other hand, while the electric resistance welded tube 1 travels the distance e from the inlet to the outlet of the high frequency coil 2, 256 (=16×16)
Pulse signal generator 10 that generates pulse signals of
The pulse signal from this pulse signal generator 10 is applied to a 4-bit binary counter 11 which generates a carry output (cp) every time 16 pulse signals are counted.

Each 4-bit binary output terminal of this binary counter 11 is connected to address input terminals A, B, C, and D of each multiplexer 31-38, respectively. Further, the carry output terminal (cp) of the binary counter 11 is connected to each shift register 21 to 2.
It is connected to the clock input terminal k of 8.

Further, the 8-bit digital signals generated in parallel from the output terminals of the eight multiplexers 31 to 38 are led to the D/A converter 12 and converted into analog signals, and then integrated in the analog integrator 13. .

The output terminal of this analog integrator 13 is connected to the input terminal of an attenuator 14 that attenuates the input to 1/16 and outputs the resultant signal. It is led to one input terminal.

The analog integrator 13 is for obtaining an analog value of the sum of all 16 digital values stored in 8 bits in the 8 shift registers 21 to 28, and converts the analog output of the D/A converter 12 into an analog value. The integration time for integration is the time for sequentially reading out all 16 digital signals stored in the shift registers 21-28 via the multiplexers 31-38,
This time is the time for counting 16 pulses by the binary counter 11, that is, the carry output (cp)
The period is Then, at the end of the integration time, the integrated value is attenuated to 1/16, averaged, and held in the sample/hold circuit 15, and then the analog integrator 13 is reset to its initial state (output is zero). Repeat the action.

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

At the start of operation, the stored contents of the shift registers 21 to 28 are all zero, and the surface temperature of the ERW tube 1 within the field of view of the optical thermometer 4 is low, so the output voltage of the optical thermometer 4 is This is different from the output voltage 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 (ΔT) between the two. This differential voltage (ΔT) is applied to the adder/subtractor circuit 7 together with the output of the integrating circuit 8 and the output of the sample/hold circuit 15, and since the output of the analog integrator 13 is initially zero, the differential voltage (ΔT) The output of the high frequency power supply 3 is controlled so that the output of the integration circuit 8 becomes equal to the output of the integration circuit 8.

The output of the high frequency power supply 3, that is, the output of the integration circuit 8 corresponding to the heat input of the ERW tube 1, is converted into a digital value by the A/D converter 9, and then converted into 16 pulses by the binary counter 11. Each time the signal is counted and a carry output (cp) is generated, it is sequentially inputted from the serial input terminals of the shift registers 21-28. In this way, while the ERW tube 1 moves from the inlet to the outlet of the high-frequency coil 2, the digital value corresponding to the amount of heat input required for heating is stored in the shift registers 21 to 2 as 16 pieces of 8-bit data.
8 is stored.

Therefore, the electric power applied to the portion of the ERW tube 1 within the field of view of the optical thermometer 4 immediately after exiting the outlet of the high-frequency coil 2 while it is traveling inside the high-frequency coil 2, that is, the amount of heat input. The signal corresponding to 8
Shift register 21 as 16 bit data
~28.

On the other hand, in addition to the carry output (cp), the binary counter 11 generates a 4-bit binary output between the carry outputs. By sequentially specifying addresses, 16 pieces of data are sequentially output using 8 bits stored in each shift register 21 to 28,
The 8-bit digital output is sent to the D/A converter 12.
After converting it into an analog signal, integrate it for 16 signals at a time.
After being attenuated and averaged, it is held in the sample/hold circuit 15, and then sent to the addition/subtraction circuit 7.
to one input terminal of the

In this way, in a continuous operation state in which the latest 16 pieces of data are maintained in each of the shift registers 21 to 28, the optical thermometer 1 is connected to the output of the high frequency coil 2.
The portion of the ERW tube 1 that appears within the field of view of 4 outputs a value corresponding to the amount of heat input received while traveling inside the high-frequency coil 2 from the analog integrator 13 via the sample-and-hold circuit 15. In the circuit 7, addition and subtraction processing is performed on the output of the comparison circuit 5 and the output of the integration circuit 8.

If the temperature of the ERW tube 1 at the outlet of the high-frequency coil 2 is the same as the set value, the output of the comparator circuit 5 is zero, and the output obtained by the analog integrator 13 and held by the sample-and-hold circuit 15 is the same as the output of the comparison circuit 5. The high frequency power source 3 is controlled to produce the same output.

If the temperature of the ERW tube 1 at the outlet of the high-frequency coil 2 differs from the set value, a deviation output is generated from the comparator circuit 5, so the output of the high-frequency power supply 3 is controlled based on the deviation output. The resulting outputs are sequentially stored in each of the shift registers 21 to 28 via the A/D converter 9.

In this way, each part of the ERW tube 1 calculates the integral amount of electric power (E Since the output of the high frequency power source 3 is controlled by comparing the actual temperature of each part of the tube 1,
The annealing temperature can be optimized.

In particular, when the high frequency power supply 3 is controlled and its output fluctuates temporarily due to a temporary deviation between the set temperature of the temperature setting device 6 and the temperature detected by the optical thermometer 4, the output fluctuation The information is stored in one stage of the 16-stage shift registers 21 to 28, and when read out, the amount of information is attenuated to 1/16, so hunting can be reduced.

Even if the advancing speed of the ERW tube 1 changes, the integral output from the analog integrator 13 also changes in inverse proportion to the advancing speed, so the output of the analog integrator 13 corresponding to the amount of heat input is influenced by the advancing speed. Because I do not receive
Optimal temperature control can be achieved even when the speed changes.

Although it is difficult to measure the actual amount of heat input to the ERW pipe 1, the power of the high frequency power source 3 (E x I)
Since this can be easily determined, the temperature is controlled by making the power of this high frequency power supply correspond to the amount of heat input.

In the embodiment described above, eight shift registers each having 16 stages are used.
The number of bits of a digital signal and the number of stages of a shift register are merely examples; other numbers may be used, and random access memory may be used instead of a shift register. can be operated.

Although the control device of the present invention has been explained using an example of annealing an electric resistance welded pipe 1, it is also applicable to the case of continuous heating of various long materials such as wire rods, pipe materials, and bar materials. By applying the present invention to various continuous heating devices in which the temperature measuring section is placed outside the heating section, it is possible to exhibit excellent effects in terms of temperature control.

[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 (ERW pipe), {2... High frequency coil, 3... High frequency power supply} Heating section, 4... Temperature measuring device, 5... Comparison circuit, 6... Setting device, 7... Addition/subtraction circuit, 8... Integration circuit, 9... A/D converter,
10... Pulse signal generator, 11... Binary counter, 12... D/A converter, 13... Analog integrator, 15... Sample/hold circuit, 21
~28...shift register, 31~38...multiplexer.

Claims (1)

[Claims] 1. A long material that has a heating section over a certain length and a temperature measuring device that measures the heated temperature near the outlet of the heating section, and that controls the heating section based on the output of the temperature measuring device. In a continuous heating device that continuously heats a long object, signals corresponding to the amount of heat input to the object are sequentially stored, and each heated part reaches the temperature measuring device. storage means for outputting the average value of all signals corresponding to the amount of heat input, and the heating section is controlled based on the deviation between the temperature obtained by the temperature measuring device and the set temperature and the output of the storage means. A control device for a continuous heating device, characterized in that it comprises a control means for controlling.