KR100225256B1 - The apparatus with auto-control input heating quantity in high wave spot welder and the control method of the same - Google Patents

Abstract

The present invention relates to a control device and a method for controlling an electric resistance welding device used to fabricate an electric sealing tube to improve welding quality, comprising: receiving means (70) for detecting electromagnetic waves formed by sparks generated at a welding site; A spark signal processor (3) which selects only necessary signals from the spark signals received through the receiving means (70), separates the amplitude components and the frequency components, and processes them into a predetermined signal form and outputs them; A heat generator 61 attached to the object to be welded 2 to generate heat of fusion; An oscillator 6 for oscillating and outputting a high frequency current supplied to the heat generator 61; A welder controller 5 for controlling the amount and frequency of current supplied to the oscillator 6; A welder power controller 4 for controlling the output of the welder controller 5; The main control unit 1 is connected to the spark signal processing unit 3 and the welder power controller 4 to control the power of the welder to receive the spark signal and to achieve the optimum welding condition.

Description

Automatic heat input control device of high frequency electric resistance welding device and the way to me

The present invention relates to an automatic heat input amount control device of a high frequency electric resistance welding device and a control method thereof. More particularly, the present invention relates to a control device and a method for improving welding quality by controlling an electric resistance welding device used when manufacturing an electric tube. will be.

In general, electric resistance welding, in which a welded portion of a metal is melted by electric resistance heat, is welded by welding a welded portion of the welded portion together with a spot welding, a projection welding, a seam welding, and a welding portion. Welding butt welding, butt welding, flash butt welding, butt seam wdlding, percussion welding, soldering machines that melt and weld metal directly have. This classification is based on the welding method for convenience, and when classified by the power supply method supplied to the welding machine, there are general AC single phase, low reactance, heat storage, and the like. Manpower pressurization, electric force pressurization, air pressurization, hydraulic pressurization, electromagnetic force pressurization, etc. are mentioned. In addition, the control method is classified into asynchronous control, semi-synchronous control, synchronous control, and computer control. Among them, computer control includes input voltage control, welding transformer input current control, welding current control, nagget voltage control, and welding power. It can be divided into control, pressing force and power control, welding condition selection control, and nagget control method.

These various types of electric resistance welding machines are to weld the welded object by the resistance heat generated by supplying a large current using the electrical resistance generated between the contact portion between the welded object, the welding principle will be described as follows.

The heat of resistance (Q) generated by the electrical resistance is 0.24I ² RT (cal), and the heat of resistance is generated in proportion to the square of the resistance (R) and the current (I). Therefore, the amount of current supplied to the object to be welded must be large, and in order to do so, a large current can be supplied with a small amount of power VA only by dropping it at a low voltage.

On the other hand, if the two welded objects overlap each other and the electrode tip is brought into contact with each other and the current is supplied, the resistance of the contacted part is the greatest, and the contacted part and the electrode tip come next. Is the next largest, with the bulk portion of the welded object having the lowest resistance. Therefore, when the current is supplied to the electrode tip, the most heat is generated in the contact portion between the welded contact, and then a lot of heat is generated in the order of contacting the electrode tip and the contacted object, and bulk parts of the welded contact.

On the other hand, in order to generate heat to the welded object and melt-bond each other, it is necessary to press an appropriate force on the welded object, and to adjust the size and duration of the current supplied according to the metal characteristics of the welded weld You can maintain good quality.

Among the electric resistance welding methods having such general characteristics, the high frequency electric resistance welding machine according to the present invention is a method of welding an object to be welded by generating an induction heating by an induction current by supplying a high frequency current to a welded portion. When a current is supplied by contacting a contact with a contact with a high frequency of 300 to 1000 kHz, a closed circuit is formed to form the shortest distance centered on the contact, and induction heating occurs at that portion to melt the contact.

Such high frequency electric resistance welding has been widely used to manufacture an electric sealing tube because the welding speed is very fast and the occurrence frequency of welding defects is low. In particular, high-frequency electric resistance welding has excellent economical efficiency and is excellent in welding quality, and is widely applied to parts requiring high quality, such as oil and gas oil pipes, oil well pipes, and mechanical structural steel pipes. Therefore, the electric tube used for such an important use must be strictly managed the defect of the welding part.

In order to minimize the occurrence frequency of weld defects in steel pipes manufactured by high frequency electric resistance welding, an automatic heat input control device has been developed and used. It detects variables of major welding variables such as the welding speed and the thickness of steel, and automatically adjusts the welding heat input to maintain proper welding conditions.

The automatic heat input control apparatus of the high frequency electric resistance welding method uses a method of using oscillation frequency variation, a bead shape, a welding temperature or a distribution thereof depending on the type of feedback signal used. In particular, the method using the oscillation frequency developed and used in New Nippon Steel (Japanese Patent, Hep. 3-34432, 52-111851) automatically adjusts the welding heat input by using the change of the oscillation frequency as a feedback signal. have. In other words, as the welding heat input increases, the oscillation frequency fluctuates gradually to the maximum, and if the welding heat input further increases, the oscillation frequency fluctuates gradually to the maximum, and when the welding heat input increases further, oscillation occurs. It is based on the principle that the fluctuation of frequency decreases again. Therefore, it is a method of automatically maintaining an appropriate welding interval by maintaining the welding heat input amount in the type 2 welding zone with the largest change in the oscillation frequency.

However, this method requires an appropriate welding range for the thickness and the welding speed of the material to be welded by changing the welding heat input amount from minimum to maximum when starting a welding operation. Due to the process there was a problem that the productivity is lowered.

The present invention to solve the above problems of the prior art, by measuring the frequency and size of the spark generated in the welding site in order to control the amount of heat input welding to the high-frequency electric resistance welding apparatus and control it by using this as a feedback signal It is an object of the present invention to provide an automatic heat input control apparatus of a high frequency electric resistance welding apparatus capable of controlling a convenient and precise heat input of welding.

In order to achieve the above object, the present invention, in the device for automatically controlling the heat input of the high-frequency electric resistance welding apparatus used when manufacturing the electric tube, receiving the electromagnetic wave formed by the spark generated from the welding site Means; A spark signal processing unit which selects only necessary signals from the spark signals received through the reception means, separates an amplitude component and a frequency component, and processes and outputs them in a predetermined signal form; A heat generator mounted on the object to be welded to generate heat of fusion; An oscillator for oscillating and outputting a high frequency current supplied to the heat generator; A welder controller for controlling an amount of current and a frequency supplied to the oscillator; A welder power controller for controlling the output of the welder controller; Automatic heat input control device of the high frequency electric resistance welding device, characterized in that the main control unit is connected to the spark signal processing unit and the welder power controller to control the power of the welder to achieve the optimum welding conditions by receiving the spark signal feedback To provide.

In addition, the present invention provides a method for controlling the optimum welding when manufacturing an electric tube using a high frequency electric resistance welding machine, wherein the amplitude and the frequency of the sparks vary depending on the magnitude of the current supplied to the heat generator. Measuring and setting a plurality of areas; Selecting an optimal welding region according to the industrial condition from the region set as the plurality of regions in the above step; Starting the welding in the region selected in the welding region selection step and measuring the amount of sparks generated during welding; Reducing or increasing the amount of current supplied to the heat generator by comparing the spark generation amount measured in the spark generation amount measurement step with the spark amount in the selected region; Provided together with the automatic heat input control method of the high-frequency electric resistance welding device, characterized in that the step of terminating when the welding is finished.

FIG. 1 is a state diagram schematically showing a current flow state when manufacturing an electric tube using a high frequency electric resistance welding apparatus. FIG.

2 is a block diagram showing a configuration of an automatic heat input amount control device of a high frequency electric resistance welding device according to the present invention.

3 is a graph showing the change in the amplitude and frequency of sparks according to the change in the heat input of the welding by region.

4 is a flowchart showing a method for automatically controlling heat input of a high frequency electric resistance welding apparatus according to another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: main control unit 2: welded object

3: spark signal processor 4: welder power controller

5: welder controller 6: oscillator

11: serial port 1 12: serial port 2

21: welding point 22: bridge

31 Spark Detector 32 Signal Separator

33: spark frequency signal processor 34: spark amplitude signal processor

35: ADC 36: μ-processor

41: μ-processor 42: DAC

70: coil antenna 61: heat generator

The configuration and operation of the automatic heating amount control device and control method of the high-frequency electric resistance welding apparatus according to the present invention will be described in detail through an embodiment of the present invention.

The accompanying drawings, FIG. 1 is a state diagram schematically showing the flow of current when manufacturing an electric tube using a high frequency electric resistance welding apparatus, and FIG. 2 is an automatic heat input control of the high frequency electric resistance welding apparatus according to the present invention. A block diagram showing the configuration of the device. And, Figure 3 is a graph showing the change in the amplitude and frequency of the spark according to the change in the amount of heat input welding, Figure 4 is a flow chart showing an automatic heat input control method of a high frequency electric resistance welding apparatus according to another invention of the present invention to be.

First, prior to explaining the configuration of the automatic heat input control device of the high frequency electric resistance welding apparatus according to the present invention, the characteristics of the spark generated when welding the metal using the high frequency electric resistance welding method, using a high frequency electric resistance welding method According to the results observed using a high speed camera when welding the welded object, it was observed that spark was generated between the edges of both steels near the welding point. In other words, the high frequency current applied to the steel melts the edge of the steel, and the molten metal is flowed by the high current of about 1000 to 3000 (Ampere) (Pinch Instability), and these come into contact to generate sparks.

It was observed that the frequency of occurrence of such sparks gradually increased with the amount of heat input of the welding and reached the maximum, and then decreased as the heat input of the welding increased further.

In addition, the size of the spark was observed to increase with the increase in the amount of heat input welding, and the increase in the amount of heat input welding was observed to decrease when the multiple sparks occur at the same time.

This process is typically shown in FIG. 1, and the amount of molten metal increases as the weld heat input amount I _t increases and the molten metal crosslinks (Bridge, 22) at a part far from the welding portion 21. Will form. At this time, a portion I ₂ of the welding current flows through the formed bridge, and the bridge is rapidly heated to generate sparks. Therefore, as the crosslinking of the molten metal is generated farther from the welding point, the current flow path difference is larger, so that the current flow fraction (I ₂ / I _t ) through the bridge is larger than the amount of current flowing through the welding point (I ₁ ). Therefore, the size of the spark also increases.

Therefore, by observing the frequency and magnitude of the sparks, it is possible to indirectly measure the amount of heat input for welding.

Therefore, in order to control the amount of heat input for welding, it is more efficient to measure and control the frequency and size of the sparks occurring in the welded portion.

The present invention relates to a device for controlling the welding heat input by using the characteristics of the spark according to the change of the welding heat input as described above, the configuration of the automatic heat input control device of the high frequency electric resistance welding device is shown in FIG. As described above, Coil antenna 70 for sensing the electromagnetic wave formed by the spark generated in the welding portion; A spark signal processor (3) which selects only necessary signals from the spark signals received through the coil antenna (70), separates the amplitude components and the frequency components, and processes them into a required signal form; A heat generator 61 attached to the object to be welded 2 to generate heat of fusion; An oscillator 6 for oscillating and outputting a high frequency current supplied to the heat generator 61; A welder controller 5 for controlling the amount and frequency of current supplied to the oscillator 6; A welder power controller 4 for controlling the output of the welder controller 5; The main control unit 1 is connected to the spark signal processing unit 3 and the welder power controller 4 to control the power of the welder to receive the spark signal and to achieve the optimum welding condition.

Here, the spark signal processor 3 receives a signal from a coil antenna 70 that detects a signal of a spark that is melted by the heat generated by the heat generator 61 and is generated at a welding site, and is a good signal. A spark detector 31 for filtering and amplifying and outputting the filtered signal; A signal separator 32 for separating and outputting the signal output from the spark detector 31 into an amplitude signal and a frequency signal; A spark frequency signal processor 33 which receives the frequency signal separated by the signal separator 32 and outputs the frequency signal as a frequency signal; A spark amplitude signal processor 34 which receives the amplitude signal separated by the signal separator 32 and outputs it as an amplitude signal; An analog / digital converter (ADC) 35 for converting and outputting an analog signal output from the spark frequency / amplitude signal processing units 33 and 34 into a digital signal; Under the control of the main control unit 1 is configured to control the operation of the spark detector 31, and converts the output of the ADC (35) is composed of a microprocessor 36 for outputting .

And, the welding machine power controller 4 is to control the output of the welding machine controller 5, the ADC 43 for receiving the state signal of the welding machine controller 5, converts it into a digital signal and outputs it; ; A DAC 42 which outputs a signal for controlling the welder controller 5 and converts the digital signal into an analog signal and outputs the analog signal; The microprocessor 4 which processes the signal for controlling the welder controller 5 through the ADC 43 and the DAC 42 under the control of the main controller 1.

1) consists of.

On the other hand, the welder controller 5 receives three-phase or single-phase AC power and generates and outputs a power having a predetermined frequency and amount of current, and is usually composed of a thyristor, an oscillation tube, and the like.

In addition, the heat generator 61 is composed of an induction coil and a contactor, which is mounted on the welded object 2 to generate heat, and the heat generator used in the high frequency electric resistance welding method usually produces a steel pipe of small diameter. An induction coil is used for this purpose, and a contactor (CONTACT TIP) attached to the edge portion of the welded object is used for manufacturing a large diameter steel pipe.

In addition, the present invention is a method of controlling the optimal welding is made when manufacturing the electric tube using a high-frequency electric resistance welding machine, as shown in Figure 4, varying depending on the amount of current supplied to the heat generator Measuring the amplitude and frequency of occurrence of the sparks and setting them to a plurality of regions (8 regions in the present invention), as shown in FIG. 3; Selecting (32) an optimum welding region according to the welding condition from the region set as the plurality of regions in the above step (31); Starting welding in the region selected in the welding region selection step 32 and measuring the amount of sparks generated during welding; The spark generation amount measured in the spark generation amount measurement step 33 is compared with the spark amount of the selected region cooling (34), and the current amount supplied to the heat generator 61 is reduced (35) or increased (351). ) Giving; At the end of the welding step 36 is completed.

An automatic heat input amount control apparatus and a control method of the high frequency electric resistance welding apparatus according to the present invention configured as described above work as follows.

First, before operating the apparatus, the amount of spark generation according to the change in the amount of heat input of the welding is measured, the area is set by the area, and the weight is set for the area. In other words, the first region has a decay value '0', the second region has a weight '1', the third region has a weight '2', the fourth region has a weight '3', the fifth region has a weight '4', the sixth region The region is set to '5', the seventh region to a weight '6', and the eighth region to a weight '7'. This area setting can be set more finely. Then, the correlation between the spark generation amount and the welding quality is tested to set an area having the optimum welding quality.

This process is measured through a lot of experiments in advance, and the amount of current supplied (welding heat input), the data on the spark, and the welding state are compared and set.

Thus, after selecting the area | region according to the welding condition through the main control part 1, welding is started and simultaneously, the spark generation amount is measured.

This spark generation measurement process is as follows.

When a high frequency power is applied to the heat generator 61 mounted on the object to be welded 2, as shown in FIG. 1, current flows, and the edges of the object to be welded are fused and advanced while the edges of the object to be welded are welded together. Joined at (21). By the way, the molten part of the to-be-welded object 2 melted by the high frequency electric current supplied forms a spark by an electrical phenomenon. This spark phenomenon is generated due to the fluidity of the melt and the electromagnetic force generated by the current flowing in the edge portion of the welded object 2, and the amount of spark generation, i.e. its amplitude and frequency of occurrence, depends on the amount of welding heat supplied. The pattern changes as shown in FIG.

Therefore, the spark signal processor 3 measures the amplitude and frequency of the sparks and feeds them back to appropriately reduce or increase the current welding heat input so that welding is performed in an optimal state. In other words, if the optimum welding state is achieved in the third region, the welding heat input amount is changed on the basis of the spark signal at this time, that is, the amplitude and the frequency of occurrence, so as to maintain the welding condition at the optimum state.

Automatic heat input control apparatus and control method of the high frequency electric resistance welding device according to the present invention made as described above by using a spark signal generated during welding when manufacturing the electric tube, the welding heat amount is appropriately changed by the optimum welding state By automatically controlling to maintain the state, it improves the welding quality and increases the productivity.

While the present invention has been illustrated and described with reference to preferred embodiments, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments, and has a general knowledge in the technical field to which the present invention belongs. Various changes and modifications may be made by the user.

Claims (4)

An apparatus for automatically controlling the heat input of a high frequency electric resistance welding apparatus for use in manufacturing an electric tube, comprising: receiving means (70) for wirelessly sensing electromagnetic waves formed by sparks generated at a welding site; A spark signal processor (3) for separating and outputting a frequency amplitude component and a frequency component among the spark signals received through the receiving means (70); A heat generator 61 attached to the object to be welded 2 to generate heat of fusion; An oscillator 6 for oscillating and outputting a high frequency current supplied to the heat generator 61; A welder controller 5 for controlling the amount and frequency of current supplied to the oscillator 6; A welder power controller 4 for controlling the output of the welder controller 5; High frequency, characterized in that the main control unit 1 is connected to the spark signal processing unit 3 and the welder power controller 4 to control the power of the welder to receive the spark signal to achieve the optimum welding conditions Automatic heat input control device of electric resistance welding device. The method of claim 1, wherein the spark signal processor 3 is melted by the heat generated by the heat generator 61 is input signal from the wireless coil antenna 70 for detecting the signal of the spark generated in the welding site A spark detector 31 which filters and amplifies and outputs a valid signal; A signal separator 32 for separating and outputting the signal output from the spark detector 31 into an amplitude signal and a spark signal; A spark frequency signal processor 33 which receives the frequency signal separated by the signal separator 32 and outputs it as an analog frequency signal; A spark amplitude processor 34 which receives the amplitude signal separated by the signal separator 32 and outputs it as an analog amplitude signal; An analog / digital converter (ADC) 35 for converting and outputting an analog signal output from the spark frequency / amplitude signal processing units 33 and 34 into a digital signal; Under the control of the main control unit 1 is configured to control the operation of the spark detector 31, and converts the output of the ADC (35) is composed of a micro-processor 36 for outputting Automatic heat input control device of a high frequency electric resistance welding device, characterized in that. The welding machine power controller according to claim 1, wherein the welding machine power controller 4 includes the welding machine controller. An ADC (43) for controlling the output of (5), receiving a state signal of the welder controller (5), converting it into a digital signal, and outputting the digital signal; A DAC 42 which outputs a signal for controlling the welder controller 5 and converts the digital signal into an analog signal and outputs the analog signal; The microprocessor 4 which processes the signal for controlling the welder controller 5 through the ADC 43 and the DAC 42 under the control of the main controller 1. 1) Automatic heat input control device of high frequency electric resistance welding device, characterized in that consisting of. In the method for controlling the optimum welding when manufacturing the electric tube using a high frequency electric resistance welding machine, by measuring the spark amplitude and the frequency of occurrence of the approximate edge portion that changes depending on the amount of current supplied to the heat generator, Setting (31) an area; Selecting (32) an optimum welding region according to the welding condition from the region set as the plurality of regions in the above step (31); Starting welding in the region selected in the welding region selection step 32 and measuring the spark amplitude and frequency occurring during welding; Comparing the measured value in the spark amplitude and frequency measurement step 33 with the amount of sparks in the selected region (34) to reduce (35) or increase the amount of current supplied to the heat generator (61); 351; Automatic welding control method of the high-frequency electric resistance welding device characterized in that the step of terminating (36) when the welding is finished.

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