JPS5924585A - Method and device for measuring electric power in high- frequency butt seam weld zone - Google Patents

Abstract

PURPOSE:To determine continuously the instantaneous value of electric power to be applied to a weld zone during welding in an automatic controlling method for welding by the measurement of high frequency current, voltage, etc., by calculating the proportional constant during high-frequency butt seam welding. CONSTITUTION:The primary voltage E1 and current I1 of a current transformer 9 of a high-frequency oscillation circuit are measured and are inputted to a synchroscope 1, the Lissajour's waveform thereof determines the voltage 2V1 in the part cut by the Y-axis. The phase difference phi between the voltage E1 and the current I1 is determined by the equation I ; further, the secondary voltage E2 and angular frequency omega of said oscillation circuit are measured and the electric power P applied to the weld zone is determined from the equation II (L0, r0- L5, r5 are respectively the self inductances and resistances of a transmission circuit, the primary and secondary sides of the transformer 9, the overall V-shaped part of the pipe to be welded, and the circumferential length part of the pipe, M is mutual inductance, and C is the capacitance of the oscillation circuit).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring the instantaneous value of electric power applied to a welding part in high frequency electric resistance welding.

High-frequency electric resistance welding is widely used for seam welding of electric resistance welding pipes because of its ability to perform high-speed welding. In this case, it is necessary to keep the power applied to the welding part constant, but until now, operators have mainly been responsible for visually observing the molten steel in the welding part and measuring the temperature of the discharge bead of the V-shaped edge after squeeze roll. I was manually adjusting the human power to W1■. With this method, there are individual differences and limitations in how the operator perceives the color of the molten steel, and in the responsiveness to changes in the surface temperature and color of the molten steel due to changes in plate thickness or pipe forming speed, and often involves cold welding or Venet welding. Welding defects called welding defects sometimes occur. Also, plate 7 of the oscillator
A method of automatically controlling oscillator transmission circuit 1 using voltage, current, and grid current as control signals has been proposed. There is heat loss in the pipe, the accuracy is poor, and it is not practical.

The inventors previously proposed a method for automatic control by measuring high-frequency current and voltage. The proportional constant corresponding to the required power factor is calculated using a synchroscope etc. for each Lee's steel pipe to be welded. However, because the proportionality constant fluctuates due to changes in the thickness of the pipe, the shape of the pipe, etc. during construction, the power calculated by was found to be different from the instantaneous value of the iH force at the actual welding part.

High frequency oscillation and load circuit in high frequency resistance welding method
As shown in the figure. Figure 1 (a) ij is an oscillation, negative I Wi circuit that includes the first part of the V-shoe and the circumference of the tube; In the same figure (cl is the oscillation and load circuit that combines the shave section, tube circumference section, and CT).

here, Lo+ro; Transmission circuit self-inductance, resistance.

L+, r+; CT-next side self-inductance, resistance.

Lz, rz: CT secondary side self-inductance, resistance, LSH'rN; Vibrator overall self-inductance, resistance, L4. r4 ;” V-shave section self-inductance,
Resistance, Ls+rs: Self-inductance of the vibrator circumference, resistance, I+: CT-secondary side current, I2: CT secondary-side current, X+: C'I'-secondary-side voltage, Ey: CT secondary-side voltage, M: Mutual Inductance, L; total self-inductance (=Lt+Lo −L's
), ■ζ: Total resistance (=r+ + ro + r+s
).

When the circuit constants shown in FIG. 1 are measured with a measuring device (LCR meter), it is recognized that they are rs)rz, ωLs))rs. Using this relationship, ■Equation (1) holds true between the current I4 flowing in the shape part and the CT-next-side current 11. Also, ■The phase difference between the voltage and current IE2'H14 of the shoe 1 part is When θ is assumed, the power factor cos θ is expressed by equation (2).

Therefore, the power P generated by (supplied to cl-) is expressed by equation (3).

・・・・・・・・・(3) Until now, the power supplied to the %V shape section was CT-
nIn was determined from the next-side current I+, the measured value of the voltage E2 on the CT secondary side, and the average value of the proportionality constant α determined in advance. However, it has been found that α is not constant during pipe making, and that automatic control to keep the electric power constant is not necessarily carried out precisely.

In view of the above-mentioned background, the present invention has been devised by using a synchroscope, an image camera, a high frequency ammeter, and a voltage n1 in combination, during pipe making, that is, high frequency electric resistance welding. Calculate the proportionality constant, knead,
It is an object of the present invention to provide a method and apparatus for continuously determining the instantaneous value of electric power applied to a welding part in a solution.

The gist of the present invention is to manually apply the voltage s't11 flow on the CT side of the high-frequency oscillation constant i path to a synchronoscope, and to cut the current waveform drawn on this synchroscope by the Y axis. The voltage value 2V+ is determined by the image safety camera and the arithmetic circuit, and the peak value E of the primary side voltage is determined by the voltage signal 1.
, E+ is input to the performance circuit and ψ=5in-'(VE
Find out the phase difference ψ between the -order (II+ voltage and current) from the -order (+), and further measure the -order current II, secondary side voltage & , and angular frequency ω and input them to the operation η- circuit, which will be described later. 2〇 (Cram school or formula (1υ) is used to find the power P for 1 welding part 1 hour.

Hereinafter, the present invention will be specifically explained and explained with reference to the drawings.

The proportionality constant α in equation (3) consists of [2 M, Ls,
rs.

It is known that L2 hardly changes during pipe making.

Therefore, it can be seen that it is sufficient to measure ω, L3, and I's during pipe making.

Figure 1: smell, r, )') r2. ωLs >> r
3, L12 is expressed by equation (4).

Therefore, the oscillation frequency f is expressed by equation (5) as 7'.

In addition to measuring the oscillation frequency f from Equation (5), the angular frequency ω can be obtained from 2πf, and Ls can be obtained from Equation (5) by nth division. Note that Lx can also be determined by measuring Kokushi and (11) since equation (6) holds true between hills 1 and 1+ in FIG.

On the other hand, if the phase difference between the island and i is ψ, then the power factor cosψ
is expressed by equations (7) and (8).

2rg 1 ~ Therefore r3 is e03 ψ, II from equation (8)
HI! It is determined by measuring +1. By the way, until now there has been no technology for measuring the phase difference between high frequency high current and 11ε pressure, and it has been impossible to obtain the instantaneous r at 1 o'clock. In the present invention, a synchroscope, an image sensor camera, and a high frequency high current output are used.
The phase difference ψ between E+ and 11 can be determined. In other words, the method for measuring 1 phase difference ψ is as shown in Figs. 2 and 3, by manually drawing the Lissajous waveform 6 by manually drawing the Buddha on the vertical axis of the synchroscope 1 and I+ on the horizontal axis, while using the image sensor The camera 2 is arranged so that its scanning line coincides with the Y'-Y axis of the synchroscope.

The image sensor camera captures a waveform 5 with two 11-1s.
” Enter the circuit 7 and here the Lissage waveform is Y 1l
Calculate and find the voltage 2V+ of the portion AB which is cut by Ql+ and increases by t. The voltage E+ is increased by the high frequency voltage i13.
seek. These voltages Vly lb+ are input to the arithmetic circuit 4 [7] and the phase difference ψ is determined according to equation (9).

-1■1 ψ-8in(-) ・・・・・・・・・(9)1 ■The electric power supplied to the shape part is calculated by formula (3), (
(i).

From (8), it can be expressed by the formula θ・0 spanning (1■). Ru.

・・・・・・−・・・・・・(M) ・・・・・・・・・Ot) In the above formula, ω! J, IHII) The variables other than 008ψ and stop 2 are almost constant during pipe making, and appropriate values can be input into the 394 machine before pipe making.

Next, an apparatus for measuring the instantaneous value of electric power applied to a welding part and its operation will be described with reference to FIG.

Output i and C of current detector 8 inserted into one side of high frequency transmission water cooling pipe 17 connecting high frequency oscillator 14 and CT9
Input the primary side voltage E+ of '1'9 into the synchroscope l.
The lj pressure 2V+ is also stopped by the image sensor camera 2 and the Lissajous waveform voltage wave $1 [circuit 7]. On the other hand, the primary side voltage of CT9 is measured at voltage N13. These arithmetic circuits 7,
Input the output total phase difference of the voltmeter 3, 1υ, to the force calculation circuit 4, and find the ψ of (11). Current detector 8
The output α■, is input to the current calculator 11 to obtain the current I+. - Still, the secondary side voltmeter of C'l'', 9 is connected to the voltage side 1.
Measure at 0. Further, the output of a search coil 15 placed near the welding portion is input to a frequency calculation circuit 16 to measure the angular frequency ω.

The l1il HII H2 Hω obtained above is input to the phase difference/power calculation circuit 4, and formula (M), (11
), calculate and find the electric power P supplied to the first part of the shoe. The power P thus obtained is input to the automatic welding control circuit 13, and the high frequency input current is controlled so that the power P is constant.

According to the present invention, the welded portion has the following features: 1. Since the electric power generated by the welding process can be measured online, it can be grasped more accurately than the lδ contact electric power, and as a result, automatic power control can be performed appropriately, and the occurrence of welding defects has almost been eliminated. Note that the present invention is applicable not only to the field of manufacturing electric resistance welded steel pipes, but also to high frequency resistance welding of copper plates, shaped steel, and the like.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the oscillation and load circuit in high frequency resistance welding, Fig. 2 is a diagram showing the phase difference measurement circuit between the CT and secondary voltage and current, and Fig. 3 is a diagram showing the synchroscope according to the present invention. FIG. 4, which shows the drawn Lissajous waveform, is a circuit diagram of the welding part power measuring device according to the present invention. 1... Synchroscope, 2... Image sensor camera, 3...-Next side 1 [1, pressure side, 4... Phase difference/'i[ force calculation circuit, 5... Image sensor camera output waveform signal, 6... Lissajous waveform, 7... Lissajous waveform voltage calculation circuit, 8... current detector, 9... current transformer CT of the high frequency oscillation circuit. 10...Secondary side voltmeter, 11...Current calculator,
13... Automatic welding control circuit, 14... High frequency oscillator, 15... Search coil. 16...Frequency calculation circuit (frequency MN). Agent Patent Attorney Toshikichi SomekawaFigure 2Figure 4

Claims (2)

[Claims] (1) Voltage E+ on the current transformer-next side of the high-frequency oscillation circuit. While measuring the current I + f, the voltage 1 of the -th +1111
Bow 1. Input the current L to the synchroscope, and find the voltage 2Vl at the part where the Lissajous waveform is cut off by YN111), and further measure the secondary side voltage 2 and the angular frequency ω of the oscillation circuit. The electric power P that can be applied to the welding part is -I. A method for measuring the power of a high-frequency electric resistance welding part, which is determined from Lt;r2: Current transformer secondary side self-inductance of high-frequency oscillation circuit, resistance, LsHrs: Total self-inductance of welded tube, resistance, L4.r4: V-shoe 1 part self-inductance, resistance, Ls, rs: Control section Self-inductance, resistance, M
; mutual inductance, C; oscillation circuit capacitance. (2), the current transformer of the high frequency oscillation circuit - connected to the next side! a primary side ammeter and a primary side ammeter of the oscillation circuit, a synchroscope that manually draws a Lissajous waveform by applying the primary (ill voltage E+), and an image sensor that scans the Lissajous waveform of the synchroscope. The camera and the previous image - output from Hinza Kamishi
, manually input the waveform signal and perform the above-mentioned Reili. - Calculate the voltage 2V+ for f<jl, where the surge waveform is cut by the Y-axis.
circuit, a voltmeter that measures the secondary voltage E2 of the oscillation circuit, a frequency meter that measures the angular frequency ω, and the V+, E+, I+, E2, and Cat inputs during welding, and the welding JI section. A power measuring device for a high-frequency electric resistance welding part, comprising a power calculation circuit for calculating power given to an error.