JPS58157579A - Method for controlling welding heat input of electric welded tube - Google Patents

Abstract

PURPOSE:To obtain high quality electric welded tubes of stable quality, by measuring circumferential temperature distribution near the electric welded part, calculating the result thereof and making deviation from the set value of a parameter having positive correlation to supplied power zero. CONSTITUTION:When feeding contacts 2 are attached to both edges of a continuously formed strip 1 and high frequency current is flowed, high frequency current 3 flows along V-shaped end face. Heating energy is thereby concentrated on the edge face, and the heated part is pressed and forge welded by squeeze rolls 4, and electric welded tubes are manufactured continuously. During the while, the circumferential temperature distribution is measured by a temperature distribution detector 7 equipped with an optical system 6 above the converging point of the seam. A controlling parameter that correlates positively with supplied power is determined and welding heat input is controlled by this parameter. That is, by controlling welding heat input to make the set value given to each parameter coincide with the actual value, welding by desired welding heat input is made possible.

Description

[Detailed description of the invention] Main hole l! The present invention relates to a welding heat input control method for an electric resistance welded pipe, in which the welding heat is controlled by measuring the temperature distribution in the vicinity of the electric resistance welded part of the electric resistance welding line and determining a parameter having a positive phase relationship with the supplied power.

ERW pipes are made by continuously bending a steel strip in the width direction of the strip, abutting both ends of the copper strip to form a tubular shape, and then applying high-frequency power to the butted portion to heat it by resistance heating or induction. It is manufactured by heating and melting and press-welding the abutted parts. When manufacturing such electric resistance welded pipes, welding heat input is a factor that particularly affects the quality of the steel pipe as a product, particularly the quality of the welded G& portion.

Conventionally, the following two methods have been used to manage the heat input into this type of electric resistance welded pipe.

Method W, 1 is a method in which an operator visually determines the heat input wA and manually sets the bath contact voltage to manage the welding voltage. This method has poor workability and is highly dependent on the skill level of the individual operator, resulting in variations in quality, deterioration of quality due to delays in welding control due to fluctuations in heating conditions, and occurrence of welding defects. There is a problem that it is difficult to obtain stable quality in the manufacture of electric resistance welded pipes, which require high strength and high toughness.

The second method is based on the temperature measurement near the ERW tube, which has become easily possible due to recent advances in temperature measurement technology. In this method, the deviation between the temperature measurement result and the set temperature is determined, and control is performed so that this deviation becomes zero. In this control method, a method has also been proposed that takes into account welding speed, welding thickness, etc. (
As shown in Fig. 1, the measured temperature tends to saturate or decrease on the high force side, and during steady welding (when the welding speed and weld thickness are constant). It is possible to judge the height of welding heat input,
There is a problem.

The present invention was invented in view of this situation, and measures the temperature distribution in the circumferential direction near the electric resistance welding part and calculates the result, thereby determining a parameter that has a positive correlation with the power supplied to p1. By calculating the parameter and performing feedback control to make the deviation from the setting y4ut zero, welder heat control for erw y: Provides law.

That is, the method according to the present invention includes controlling the welding heat input to 1 so that the distribution area of the portion of the temperature distribution near the welding point exceeding the reference temperature becomes a set value, and controlling the welding heat input to 1 so that the width of the portion exceeding the reference temperature is set. controlling the welding heat input so that the
Or, there is a 4I-mold in establishing a new reference value temperature that divides the peak temperature near the welding point and the above reference temperature by a predetermined ratio, and controlling the welding heat input so as to reach the set value temperature. .

Next, the theoretical basis on which the present invention was made will be explained.

Figure 2 is an explanation of the method for manufacturing electric resistance welded pipes by high-frequency welding.
When the power supply contact 2 is attached to the inner edge of the knob 1 and a high-frequency current is applied, the high-frequency current 6 flows along the ■-shaped end face, thereby the heating energy is concentrated on the edge face, and the heated part is transferred to the squeeze roll 4. Steel pipes can be manufactured continuously by pressurizing and forging.

In order to quantitatively understand the heat input state at the seam convergence point 5, an optical system 6 is installed above the seam convergence point 5.
An rJ detector 7 is arranged.

FIG. 6(4), (Bl', (C1) are examples of the temperature distribution in the diurnal direction obtained by the temperature component 15 detector 7, respectively.

In addition, the welding conditions at this time were a pipe outer diameter of 114.6 mφ,
The wall thickness was 6.35 wt. 6th
Prisoner 9 has a low welding machine voltage, that is, a low heat input state, @6 Figure C
B+ is a normal welding state, IN5 diagram (C1 is an example of temperature distribution in a state where the welding machine voltage is high, that is, a high heat input state).

As is clear from these figures, the peak temperature of high heat input welding (Fig. 6 (C)) is almost the same as that of normal welding (*51V■), but the width of the distribution is wider. There is. Please note that with low heat input (Fig. 6 (AJ')), the peak temperature is low and the heating width is narrow.The following parameters can be obtained from such temperature characteristics.

(a) Beak temperature P; maximum temperature in the obtained temperature distribution. As shown in Prisoner No. 59, a conventional radiation thermometer, 2
Similar to the measurement results using color thermometers, etc., there is a tendency to saturate on the high mass side.

(b) S, = Ja'TdX; reference temperature 'r,
(The area value corresponding to the welding heat input in a heating width (ba) of 1:1 or more (see Figure 4). However, T: temperature distribution, x width direction am, Figure 5 1) show.

(cl' SR = peak temperature (B x reference temperature T
This is a case in which the heating width (b-a) of owC1 or more is simply determined, and the characteristics shown in FIG. 5 are shown.

(dJ W = b - a ; Heating width above the reference temperature TO (u (see Figure 4 jfit). Figure 5 (Q shows its characteristics).

(・) Half width H = ('(Peak temperature P-T,) + T.)
) heating width = d − c (see Figure 4); 5th
Figure 2) shows its characteristics.

Note that the reference temperature T·('Q is indicated as 1200cc+ in the figure, but this temperature is determined by taking at least the following two conditions into consideration.

■ Reference temperature To (IC) must be equal to or lower than the peak temperature during welding at which cold welding defects occur.

■ The resolution of the temperature distribution detector, and the calculation time and capacity constraints of the calculator, should be as large as possible.

As is clear from Fig. 5 (4) to Fig. 5 Q)l, except for the case of peak temperature P in Fig. 5 (A), the control parameters 8B, as, and W% H are all determined by the welding machine. Voltage E,
Since these parameters show a significant positive correlation, it is possible to quantitatively understand the heat input state.

Therefore, each parameter has a set value of 8!10 r Sto
If ego + HO is provided and the welding heat input is controlled so that the set value and the actual value match, welding with the desired welding heat input becomes possible. Of course, it is sufficient to use any one of the above parameters as a control parameter.

Next, embodiments of the method according to the invention will be explained with reference to the drawings.

! ! 611d is a block explanatory diagram of an apparatus for carrying out a method according to an embodiment of the present invention, and FIG. 7 is a block explanatory diagram illustrating a part of FIG. 6 in more detail.

The optical system 6 and the temperature distribution detector 7 are installed above the seam convergence point 5. The optical system 6 is composed of a lens, a filter, etc., and has an air purge and a water cooling jacket to prevent the lens and filter from being damaged or clouded.

t7t, this optical system 6 uses an optical fiber such as a glass fiber 41.

The temperature distribution detector 7 is m* separated from a temperature distribution sensor 71, a driver 72 for reading out each element of the temperature distribution sensor 71, and a video signal amplifier 76. The temperature distribution sensor 71 forms an image of the brightness distribution in the inner peripheral direction of the seam portion via the optical system 71 . As this sensor, for example, a photodiode array (linear array, CCD, etc.) is used. And its output is a video signal booster.
1m75 is supplied.

The temperature distribution detector control section 8 includes a start pulse generator 8
1, an A/D converter 82, a brightness distribution storage circuit 84, a temperature distribution storage circuit 85, and a sequence circuit 86.

The start pulse from the start pulse generator 81 activates the driver 72 of the temperature distribution detector 7, and the linear array 71 is scanned by this driver. The 'i''L image video signal obtained by this scanning is amplified by a video signal amplifier 75, passed through an A10ffi converter 82, a brightness distribution storage circuit 85, and converted into a temperature signal by a temperature conversion circuit 84. Then, it is stored in the temperature distribution storage circuit 85.The temperature distribution stored at this time is, for example, as shown in FIG.
A), CB).

(The content is as shown in C1.) The sequence circuit 86 controls the timing of the start pulse generation,
This circuit adjusts the timing of reading, reading, calculation, etc. of the memory circuits 83 and 85.

In step 311B9, the temperature distribution stored in the temperature distribution storage circuit 85 is read out, and calculation is performed to obtain the above-mentioned control parameter, for example, the half value @H.

The calculation in this calculation unit 9 is not the upper value H, but S! l
+ 81 + W is any control parameter that stutters.

Arithmetic unit 9″″! : The calculated control parameters are as follows:
& is supplied to the heat input control calculation section 10.

This calculation unit 10 smoothes the input numerical value according to the alteration status of the normal state, and calculates the set value HO (or
81141 +JB1 p Wo ) and calculate a corrected value of the welding machine voltage corresponding to the welding heat input according to the deviation. This correction value signal is supplied to the high frequency oscillator power supply section 11, whereby the welding machine voltage 12 is feedback-controlled so that the welding heat input becomes an appropriate value.

In the above embodiment, the parameters for S welding ripening are determined based on the temperature distribution in the vicinity of the melted part, and simple feedback control is performed.
Needless to say, the present invention can also be applied to a control system that feed-forwards Is wall thickness, etc.

For example, as shown in the block diagram of an apparatus for carrying out a method according to another embodiment of the present invention in FIG.
The thickness of the steel plate 1 of 11171I is detected by a plate thickness detector 20, and the speed detector 21 detects the transfer speed of the steel plate. These plate thickness and speed signals are then supplied to a set temperature calculator 22, where the set temperature is determined. In the present invention, the set value Ha (or S, . . . , Sl, WO) of the control parameter is further determined based on this temperature, and this set value is supplied to the heat input control calculation section 10. That is, in relation to the above embodiments, it can be said that this is a book in which the set values of control parameters change in response to changes in welding conditions. Therefore, the temperature distribution detector 7, the temperature distribution detector control s8, and the arithmetic unit ? , heat input control s10, and high frequency oscillator circuit power supply section 11 are similar to those in the above embodiment.

As is clear from the above explanation, the method according to the present invention
The temperature in the circumferential direction near the electric resistance welding part, i't-, is measured, and the control parameters that have a positive correlation with the supplied power are determined, and the welding heat input is controlled using the control parameters.
A high-quality and stable electric resistance welded part is obtained, which makes it possible to manufacture high-quality electric resistance welded pipes.

[Brief explanation of drawings]

Figure Wc1 is a characteristic diagram of the measured temperature of the electric resistance welding part, Figure 2 is an explanatory diagram of the manufacturing method of electric resistance welded pipes by high frequency welding, Figure 6, CB
), (C) are characteristic diagrams of the temperature distribution in the circumferential direction, W, and 4 are the theory for determining the control parameters related to the main hole 1j11 (Fig. #4, Iris 5), (Bl, (C)
), (D are characteristic diagrams of control parameters, 6th
The figure is a block explanatory diagram of an apparatus for implementing a method according to an embodiment of the present invention, FIG. 7 is a block explanatory diagram showing a part of the block explanatory diagram of FIG. 6 in more detail, and FIG. Numerical block theory f! for implementing the method according to another embodiment of the present invention! This is diagram A. 1... Strike IJ knob, 2... Power supply contact, S...
High frequency current, 4... Squeeze roll, 5... Seam convergence point, 6... Optical system, 7... Temperature distribution detector, 8
...Temperature distribution detector control section? ... Arithmetic section, 10.
...Heat input control calculation section, 11...High frequency oscillator power supply section,
12... Melt** voltage. Agent Patent Attorney Masaru Sato Year 5th r21(A) Shigeru 5th m(s) No.5
Town C) Figure 5 (D) +3.1 f3
．． 3 13.5: Conflict tIPu-Ep (kv) W-
↑luxury! (Beak n Ep'kv) Figure 6 Procedure Supplement 1 Written by: (Volunteer) 1.1' Director General, Mr. Voluntary, 1982 2
++KOn1, (Indication Patent Application No. 15'41155 No. 2, Title of Invention Method for Welding Heat Input Control Method for ERW Tubes 4, Agent (1) Page 3 of the specification, line 12, "possible" is replaced with "possible" (2) W14 specification, page 4, line 11, “2nd @wa” is amended as “impossible”.
Correct it as "Figure 2 (4), @". (3) Mei 11 Book 1114m [line 12 rlltIl
Correct lK & iteJ as "in (4) of the same figure". (4) The following is added after "...manufactured" on page 4, line 18 of the specification. [(6) in the same figure shows the case of the induction** method, and when a high frequency current is passed through the working coil 2-1, steel pipes are manufactured continuously in the same way. (5) Specification, page 11, No. 2
In line 0, ``The second cabinet'' is corrected to ``Figure 2 (4), @ is respectively''. (6) 11 of page 12 of the specification, line 11 “Power supply contactor”
K, r2-1... working coil" is added. (7) If the book "Figure 2" of the drawings is marked in red as the attached sheet amended drawing nil, it will be amended as "No. 211(A)J." (II) If the attached sheet amended drawing is added to the drawings, To)
replenish. (9) Amend No. 5 [1] of the drawings to the attached amended drawings. Above Figure 1 Figure 2 (A) Figure 2 (8) 7 No'2-1- Figure 5 (A) Figure 5 (8) (P(
kv) Figure 5 (C) Figure 5 (D)

Claims (3)

[Claims] (1) A method for controlling welding heat input of an electric resistance welded pipe, characterized by controlling welding heat input so that the distribution area of the portion of the temperature distribution near the welding point exceeding a reference temperature becomes a set value. (2) If welding heat input is controlled so that the width of the part of the temperature distribution near the welding point that exceeds the reference temperature is the set value, '1
A method for controlling welding heat input of an electric resistance welded pipe using fr% characteristics. (3) It is characterized by setting a precise reference value temperature that internally divides the peak temperature near the welding point and the reference temperature by a predetermined ratio, and controlling the 1W class human heat to reach the set value temperature. Method for controlling welding heat input of ERW pipes.