JP2819779B2 - Heat input control device for ERW pipes - Google Patents

Description

The present invention relates to a welding heat input control device for an electric resistance welded pipe.

B. Summary of the Invention The present invention relates to a heat input control device for an electric resistance welded pipe in an electric resistance welded pipe production line, which obtains respective heat input amounts by fuzzy inference based on moving and stationary heating regions by an intermediate variable, and synthesizes these heat input amounts by fuzzy inference. By using fuzzy inference in the section to set the optimal heat input as a control amount, it is not necessary to identify various parameters in the linear approximation formula, and the number of control rules can be reduced.
In addition, it is possible to smoothly perform the rising control of the heat input control.

C. Conventional technology In an ERW pipe production line using an induction heating device, heat input control is performed to improve the welding quality in ERW pipe welding, stabilize the quality, and significantly improve the production yield. I have.

FIG. 8 shows an induction type high-frequency electric resistance welded pipe production line, where 1 is a work coil for electromagnetic induction, 2 is a squeeze roll, 3 is a material to be welded, 4 is a V seam, 5 is an electric resistance welded pipe, 6 is a high-frequency oscillator.

The work coil 1 is arranged at the front stage of the squeeze roll 2, and is used to form a multi-stage forming roll (not shown).
When a high-frequency current is applied to the V seam 4 made of the raw material 3, the butted edges are heated by the high-frequency current and then pressure-welded by the squeeze roll 2.

In the above-described ERW pipe welding, conventional heat input control means for controlling a high-frequency current flowing through the V seam 4 is as follows.
Two control means are employed.

(1) Manual control means for the operator to visually observe the temperature (fire color) of the welded portion, observe the shape of the cut weld bead, and manually adjust the heat input based on these conditions.

(2) Speed-linked control means for detecting the feed rate of the material to be welded and adjusting the amount of heat input corresponding to the feed rate by the output of the function generator.

(3) Temperature control means for detecting the temperature of the weld and controlling the temperature to be constant.

However, the heat input control means (1) to (3) are still insufficient in the following points (a) to (c).

(A) It cannot follow rapidly changing factors such as a change in the feed speed of the material and a change in the plate thickness.

(B) At the time of starting and stopping, welding cannot be performed near a feed rate of zero, and an open pipe is generated.

(C) Due to these factors, excess or deficiency of heat input occurs, and therefore, a penetrator (a state in which oxides such as scale are entangled in the welded portion and welding is poor), cold welding (incomplete welding at low temperature), etc. , And good welding quality cannot be obtained.

D. Problems to be solved by the invention In order to solve the above-mentioned problems (a) to (c),
The feed rate of the material to be welded is detected and input to an arithmetic processing unit, and a relational expression between the feed rate and the optimal welding heat input (described later)
Based on this, it has become possible to calculate the welding heat input corresponding to the detected feed rate and to perform online control by a feedforward method.

The main control element of the feedforward system is the feed rate of the raw material for the same plate thickness, the same outer diameter, and the same steel type. The control section includes a moving heating area and a static heating area. When the heat input amounts P ₀ and P ₁ feed speed in each area are used as parameters, P ₀ = av + b (1) P = e / cv + d + F ... (2)

From the above equations (1) and (2), the heat input amount P in the heat input control device is obtained.
Is given by the following equation.

P = P ₀ + P ₁ = av + b + (e / cv + d) + f (3) where a, b, c, d, e, f: parameters, v: feed speed However, in the above-mentioned method, feed including a nonlinear element Since the entire speed range is approximated by the above equation (3), a, b, c, d, e, f
Is difficult to identify, and there is a problem in reproducibility.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a heat input control device for an electric resistance welded pipe, in which identification of various parameters is not required and control of rising from a stationary heating region to a moving heating region can be smoothly performed. The purpose is to provide.

E. Means for Solving the Problems The present invention provides a first deviation detecting unit for detecting a deviation between a feed rate of a tube material and a reference feed speed set value in welding heat input control of an electric resistance welded pipe; A second deviation detecting unit for detecting a deviation between the feed speed of the state and the set value of the state change speed, and a deviation output of the first deviation detecting unit are input, and when the speed is equal to or higher than the reference feed speed, an inference result based on the moving heating area fuzzy inference is obtained. A fuzzy estimating unit for determining a moving heating region, which outputs a heat input amount at which the heat becomes effective as an intermediate variable, and a deviation output of the second deviation detecting unit are inputted. A fuzzy inference part for determining the static heating area which outputs the amount of heat input for which the inference result is valid to the output as an intermediate variable, and a fuzzy inference for moving and stationary heating area based on the intermediate variables transmitted from the two inference parts. A heat input amount and a deviation output of the first and second deviation detection units are input, and a fuzzy inference synthesizing unit that sends out an optimum heat input amount with respect to a feed rate from the input and an optimal heat input amount sent from the fuzzy inference synthesis unit are controlled. And a variable power supply for heating the tube material.

F.Action The intermediate variable is the amount of heat input in the moving heating area where the inference result is valid at or above the reference feed rate, and the amount of heat input in the stationary heating area where the inference result is effective from the zero feed rate to the state change rate. Output as For both outputs, the fuzzy inference synthesis unit infers the optimal heat input for the current feed speed of the tube material taking into account the state change speed deviation and the reference speed deviation value, and controls the variable power supply unit based on the inference result. .

G. Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a pipe material roll-formed into a pipe shape
11 is a work coil located at the front of the squeeze roll 12.
The V-seam portion 11A is heated by the 13 high-frequency current. The high-frequency current supplied to the work coil 13 is stepped and rectified by the DC high-voltage unit 15 in AC power whose voltage is controlled by the variable power supply unit 14. This high-voltage DC power is supplied to the high-frequency oscillation unit 16,
A high-frequency current is extracted from the oscillating unit 16, and the high-frequency current is extracted from the matching transformer 17.

Reference numeral 18 denotes a speed detector, which detects the feed speed v _t of the tube material 11, and the detected feed speed v _t
1, is supplied to the second deviation detecting units 19 and 20. First, reference speed setting value to the second difference detecting section 19, 20 v _s and state change speed setting value v
_x is respectively given, these values v _s, v deviation of _x and v _t delta
Get v _s , Δv _x at the output.

These deviations v _s and v _x are the fuzzy inference unit for determining the amount of heat input in the moving heating area (hereinafter referred to as “moving heating inference”) 21 and the fuzzy inference unit for determining the amount of heat input in the stationary heating area (hereinafter referred to as “static heating inference”) 22.
Is entered separately for each. The former moving heating inference 21 is for obtaining an intermediate variable% P ₀ that makes the inference result effective when the feed speed v _t is equal to or greater than the state change speed, and the latter stationary heating inference 22 is from the feed speed zero to the state change speed. it is intended to obtain the intermediate variable% P ₁ to enable the inference result.

The obtained intermediate variables% P ₀ and P ₁ are input to the fuzzy inference synthesizing unit 23. This fuzzy inference synthesis unit 23 intermediate variable%
Deviation Δv of the first and second deviation detectors 19 and 20 with respect to P ₀ and% P _1
x (state change speed deviation) is for obtaining an optimum heat input P _t for Delta] v _s in consideration of the (reference feed speed deviation) v _t (current feed rate). Variable power supply unit 14 is controlled by the optimum amount of heat input P _t which is output from the fuzzy inference synthesis unit 23.

 Next, the operation of the above embodiment will be described.

The feed speed v _t of the tube material 11 is detected by the detector 18. The detected feed speed v _t is set by the first and second deviation detectors 19 and 20 to the set value v _s ,
v is compared to _x, the deviation Delta] v _s, the Delta] v _x is outputted from the first, second difference detecting section 19, 20. The deviations Δv _s and Δv _x are fuzzy inferred by the moving heating inference 21 and the stationary heating inference 22 according to the control rule explanatory diagram shown in FIG. In the control rule of FIG. 3, R _{1 to} R ₃ are rule examples of the moving heating inference 21, and R _{n to} R _{n + 6} are rule examples of the static heating inference 22. Also, R _x and R _{x + 1} are rule examples of the fuzzy inference synthesis unit 23.

For example, in the rule example of FIG.
When you run a 22 rule R _1, the intermediate variable% P ₁ of the output is a medium (medium). Further, when the mobile heating reasoning 21 executes the rules R _n, intermediate variables% P ₀ of its output is very small. These intermediate variables% P ₀ and% P ₁ are input to the fuzzy inference synthesis unit 23. When fuzzy inference synthesis section 23 intermediate variables are input, obtaining a deviation Delta] v _s, in consideration of the Δv _x% P ₁ or% P ₀ fuzzy inference to heat input P _t to the output. Variable power supply section 14 by the heat input P _t is controlled, the high-voltage DC unit 15,
The tube material 11 is heated with the optimal heat input via the high-frequency oscillator 16, the transformer 17, and the work coil 13.

If the control rules shown in FIG. 3 are used, the variable power supply section 14 is controlled in an ideal heat input control pattern as shown in FIG.

4 to 7 are explanatory diagrams showing examples of membership functions. FIG. 4 is an example of a membership function of Δv _x (v−v _x ), and FIG. 5 is Δv _s (v−v _s ). 6 is an example of a membership function of v, and FIG.
P _0,% is a membership function example of P _1.

If the heat input of the tube material 11 is performed using fuzzy inference as described above, the heat input can be controlled similarly when the operator operates.

H. Effects of the Invention As described above, according to the present invention, by controlling the heat input control in the ERW pipe production line using fuzzy inference, the control algorithm of the feedback control with the feed rate as the main factor is realized. It is not necessary to identify various parameters of the linear approximation formula, and the control rules for the stationary heating area and the moving heating area are separately expressed to reduce the number of rules and to shift from the stationary heating area to the moving heating area. There is an advantage that control (rise control) can be performed smoothly.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is an ideal heat input control pattern diagram in manufacturing an electric resistance welded tube, FIG. 3 is an explanatory diagram showing an example of a control rule, FIG. 7 is an explanatory diagram showing an example of a membership function, and FIG. 8 is a schematic perspective view showing an induction type high-frequency electric resistance welded pipe production line. 11 ... Tube material, 12 ... Squeeze roll, 13 ... Work coil, 14 ... Variable power supply unit, 15 ... High voltage DC unit, 16 ... High frequency oscillation unit, 17 ... Transformer, 18 ... Speed detection Vessels, 19,20
... First and second deviation detectors 21... A moving heating area heat input amount determining fuzzy inference section, 22... A stationary heating area heat input amount determining fuzzy inference section, and 23.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H05B 6/06 H05B 6/10 G05B 13/02 G05D 23/00 G05D 23/19

Claims (1)

(57) [Claims] In a welding heat input control of an electric resistance welded pipe, a first deviation detecting unit for detecting a deviation between a feed speed of a tube material and a reference feed speed set value, a feed speed of a tube material and a state change speed setting. When a deviation output from the second deviation detection unit for detecting a deviation from the value and a deviation output from the first deviation detection unit are input and are equal to or higher than the reference feed speed,
The moving heating area determining fuzzy inference unit that sends out the heat input that makes the inference result by the moving heating area fuzzy inference effective as an intermediate variable and the deviation output of the second deviation detection unit are input, and the feed rate changes from zero to a state change. By the speed, the stationary heating area determining fuzzy inference unit that sends the heat input amount at which the inference result by the static heating area fuzzy inference becomes effective to the output as an intermediate variable, and the moving and stationary heating by the intermediate variable sent from both the inference units A fuzzy inference synthesizing unit which receives a heat input amount based on a region fuzzy inference and a deviation output of the first and second deviation detection units and sends out an optimum heat input amount with respect to a feed rate, and an optimum heat input amount transmitted from the fuzzy inference synthesis unit And a variable power supply for heating the tube material.