JPH05230555A - Method for controlling annealing machine of weld zone of electric resistance welded tube - Google Patents

Abstract

PURPOSE:To provide the method for controlling the temp. of an annealing machine which can always stably control the, temp. with good responsiveness and is simple and low in cost. CONSTITUTION:Information Tn on an outlet side temp., information Dn on the wall thickness of an electro-resistance welded tube, information Tn on the difference between the inlet side temp. T1 and the outlet side temp. T2 or the information Vn on a moving speed is inputted to a program controller 1. This program controller 1 forms a data table 5 in accordance with the inputted information and makes interpolation calculation by this data table 5 in accordance with the thickness of the electro-resistance welded tube, the outlet side temp., the difference between the inlet side and outlet side temps. and the moving speed during the heating of the electro-resistance welded tube 3 by the annealing machine 2. The controller outputs the electric power command value PT obtd. by adding a corrected electric power value Pb by PID control to a calculated electric power value Pt to the annealing machine 2, thereby controlling the temp. of the electro-resistance welded tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annealing machine control method for controlling the heating temperature of an electric resistance welded pipe weld.

[0002]

2. Description of the Related Art An electric resistance welded pipe is formed into a tubular shape by bending both end edges of a rope to be continuously fed, and heats the contacted edge portions with high frequency. Lateral pressure is applied and welded to produce a pipe.

The electric resistance welded pipe manufactured in this manner runs in the axial direction toward the annealing machine. During the running, the welded portion is electromagnetically heated by the annealing machine at a high frequency of 1 to 10 KHz, and annealed and normalized to remove residual stress and improve the structure. In recent years, as the quality of electric resistance welded pipes has improved, there has been an increasing demand for accuracy of heating temperature in the heat treatment process of the welded portion.

[0004]

Generally, the heat treatment temperature control is performed by a PID controller which feedback-controls the measured temperature. However, when the lot of ERW pipes to be manufactured is changed, the time constant of the control system changes due to the change in the wall thickness of ERW pipes or the change in traveling speed, and there is a waste due to the difference between the annealing position and the temperature measurement position. It is difficult to perform stable control because the time changes.

Therefore, as a solution to this problem, the present applicant changes the control gain according to the wall thickness of the electric resistance welded pipe and the traveling speed,
We have proposed an induction heating device that performs stable control (Japanese Patent Laid-Open No. 63-63242).
-68282). This device can perform stable control in a steady state, but there is a problem that a response is delayed when the wall thickness of the electric resistance welded pipe and the traveling speed are changed. Further, at the start of annealing, the response is poor due to feedback control, and it takes time to reach an appropriate temperature, resulting in poor yield. Furthermore, the adjustment of the control system as described above has a problem that enormous effort is required. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for controlling an annealing machine of an electric resistance welded pipe welded portion, which has good responsiveness and whose control adjustment is easy.

[0006]

According to the present invention, there is provided a method for controlling an electric resistance welded pipe welded part annealing machine, in which a running welded part of an electric resistance welded pipe is fed toward an electric annealing machine to heat the welded part. In the method of controlling the temperature of the pipe weld, based on the annealing machine outlet side temperature, the annealing machine inlet side outlet side temperature difference, the wall thickness, the traveling speed and the electric power value at that time in the steady state of the actual operation of the electric resistance welded pipe. The process of making a data table, the process of obtaining the required power value of the annealing machine by interpolation calculation with the values of the data table, and the power command value to the annealing machine by adding the correction value by PID control to the required power value. And a determining step.

[0007]

In the annealing machine temperature control method of the present invention, the outlet side temperature of the electric resistance welded pipe, the inlet side outlet side temperature difference, the wall thickness,
A data table is created for the traveling speed and the electric power value of the annealing machine at that time. Unlike feedback control, which adjusts the electric power each time depending on the measured temperature during running, the electric power to the annealing machine is determined based on the values in the data table according to the conditions at the start of annealing. Good temperature control can be performed. At the same time, PID control is performed and the obtained correction power value is added.
More precise control can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic block diagram showing a control system used for implementing the present invention. ERW tube 3 is
It is fed from the left side to the right side in the drawing toward the annealing machine in the axial direction thereof with the welded part on the upper side. The annealing machine 2 is arranged above the electric resistance welded pipe 3. The wall thickness of the electric resistance welded pipe and the set temperature on the outlet side are set in the programmable controller 1, and by the control of the programmable controller 1, the annealing machine 2 causes the electric resistance welded pipe 3 to operate.
Heating the weld. Further, an inlet side thermometer 71 is arranged on the upstream side of the annealing machine 2 and an outlet side thermometer 72 is arranged on the downstream side thereof to detect the inlet side temperature T1 and the outlet side temperature T2 of the surface of the welded pipe 3 welded portion, respectively. is doing. The inlet side temperature T1 and the outlet side temperature T2 are input to the programmable controller 1, and the inlet side outlet side temperature difference is calculated here. A speed detector 4 is arranged below the electric resistance welded pipe 3 to measure the traveling speed V of the electric resistance welded pipe 3 and input it to the programmable controller 1.

In the programmable controller 1, the thickness information Dn of the electric resistance welded pipe 3, the outlet side temperature information Tn, the traveling speed information Vn, the inlet side temperature T1 and the outlet side, which are operation data accumulated from the data accumulated in the past, are used. A data table 5 is created based on the temperature difference information ΔTn, which is the temperature difference from the temperature T2, and the power value information Pn, which is the power value of the annealing machine at that time, and the data table 5 is further enhanced. In order to achieve the above, the above-mentioned information in the steady state in the subsequent operation is added to the data table 5 by the procedure described below and updated.

When annealing the welded portion of the electric resistance welded pipe, the current wall thickness D, traveling speed V, outlet side temperature T2, inlet side outlet side temperature difference ΔT are collated with the data table 5, and corresponding data or information is obtained. If the combination exists, the calculated power value Pt corresponding to this data is calculated. If it does not exist, the calculated power value Pt is calculated by the interpolation calculation described later using the values in the preceding and following data table 5 closest to the data.

A method of creating the data table 5 and a method of controlling the temperature will be described. The data table 5 is the output side temperature information Tn, which is the data accumulated in the past, the wall thickness information Dn of the electric resistance welded pipe, the temperature difference information ΔTn between the input side temperature T1 and the output side temperature T2, the traveling speed information Vn, and the corresponding information. This data table 5 is sequentially updated with the values at the time when these data become substantially constant during annealing. In the data table 5, each data is divided into blocks. For the wall thickness information Dn,
Less than 5mm, 5-8mm, 8-11mm, 11-14mm, 14-17mm, 17
Output temperature information Tn is less than 850 ° C, 8
Blocking is performed in four ways of 50 to 900 ° C, 900 to 950 ° C, 950 ° C or more, and three types of temperature difference information ΔTn less than 50 ° C, 50 to 100 ° C, 100 ° C or more.

As actual operation data at the present time, when the outlet temperature Ta, the wall thickness Da, the traveling speed Va, and the temperature difference ΔTa,
The interpolation calculation for obtaining the calculated power value Pt based on the data table 5 described above is performed as follows.

D _{L and} D _H are selected as the wall thickness table values immediately before and after the wall thickness Da. Then, as the last speed table value to the running speed Va, the V _L1, V _L2 relative to D _L of the thickness table value, the V _H1, V _H2 against D _H, respectively 2
Select the latest price for each type. As for the output side temperature Ta, two types of _output side temperature table values are provided for each of the traveling speed table values V _L1 , _VL2 , V _H1 , and V _H2 .
_L11, T _L12 , T _L21 , T _L22 , T _H11, T _H12 , T _H21, T
Similarly, for the temperature difference ΔTa, _H22 is selected, and two latest temperature difference table values are selected for each output side temperature table value, and ΔT _L111 , ΔT _L112 , ΔT _L121 ..., Δ
_Let T _H111 , ΔT _H112 , ΔT _H121 ... Calculated power values P _L111 , P _L112 , P _L121, ..., P _H111 , P _H112 , P _H121 corresponding to these 16 types of temperature difference table values, _{respectively.}
… Decide.

[0014]

[Equation 1] The same calculation is performed for P _L12, P _L21, P _L22, P _H11, P _H12, P _{H21, and} P _H22 .

[0015]

[Equation 2] The same calculation is performed for P _L2 , P _H1 , and P _H2 .

[0016]

[Equation 3] The same is true for P _H.

[0017]

[Equation 4]

On the other hand, the programmable controller 1 has
The PID controller 6 is built in, and in this PID controller 6, the deviation between the outlet set temperature R and the actual outlet temperature T2 is input via the adder 8. In order to eliminate this deviation, PID calculation by normal feedback control is performed, and the corrected power Pb is output. This correction power Pb is added to the adder 9
At the above, the calculated power value Pt is added and output as a power command value PT, and the welded portion of the electric resistance welded pipe 3 is annealed.

FIG. 2 is a graph showing changes in the outlet temperature T2 and the power command value PT when the traveling speed changes according to the present invention. The solid line shows the method of the present invention, and the dashed line shows the case where the initial value is high in the conventional method using the feedback control shown in the above-mentioned JP-A-63-68282, and the broken line shows the case where the initial value is low in the same conventional method. ing. According to the method of the present invention, the outlet side temperature T2 approaches the outlet side set temperature R sooner than the conventional control method, and a constant temperature can be stably maintained. Also, it can be seen that the time required for the power command value PT to reach a steady state is significantly shortened.

Further, in the present invention, since the correction is performed by the feedback control, the outlet temperature approaches the outlet set temperature without limit. Accordingly, the output side temperature information may include the output side set temperature.

[0021]

As described above, in the method for controlling an electric resistance welded pipe annealing machine according to the present invention, the electric power value is calculated from the data tabulated based on the steady-state operation data in the past actual operation, and the annealing machine is operated. Since it is given, control can be performed in a feedforward manner, and even if the traveling speed, wall thickness or inlet temperature of the electric resistance welded pipe is changed, excellent responsiveness control is performed.
Moreover, since the correction power value by PID control is added to the power value, stable control can be performed. Further, since the data amount is small and the electric power value can be obtained by a simple calculation formula, a general-purpose controller can be used, and the present invention has excellent effects such as simple and low cost.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a control system used for implementing the present invention.

FIG. 2 is a graph showing changes in an outlet temperature T2 and a power command value PT according to changes in traveling speed according to an embodiment of the present invention.

[Explanation of symbols]

 1 Programmable controller 2 Annealing machine 3 ERW pipe 4 Speed detector 5 Data table 6 PID controller 71 Inlet thermometer 72 Outlet thermometer 8,9 Adder T1 Inlet temperature T2 Outlet temperature Dn Wall thickness information Vn Travel Speed information ΔT Temperature difference information Tn Outlet temperature information Pn Power value information Pt Calculated power value Pb Corrected power value PT Power command value

Claims (1)

[Claims] 1. A method for controlling the temperature of the electric resistance welded pipe welding part by feeding the heated welded part of the electric resistance welded pipe toward an electric annealing machine to heat the welded part, and in the steady state of the actual operation of the electric resistance welded pipe. Process of making a data table based on the annealing machine outlet side temperature, the annealing machine inlet side outlet side temperature difference, the wall thickness, the traveling speed and the electric power value at that time, and the annealing machine by interpolation calculation with the value of the data table. The process of obtaining the required power value of
And a step of determining a power command value to the annealing machine by adding a correction value by ID control, and an annealing machine control method for an electric resistance welded weld.