JPH0747214B2 - Arc control method in TIG welding - Google Patents

Description

TECHNICAL FIELD The present invention relates to an arc control method in TIG welding, and more specifically, it is possible to automatically and instantaneously and accurately control an arc. The control method of the arc in the possible TIG welding.

[Prior Art] As is well known, the TIG welding method is used for butt, overlap, or fillet welding of materials having high thermal conductivity such as aluminum. In recent years, demand for improved productivity and energy saving has increased, and high-speed welding has been performed using the TIG welding method.

However, when performing TIG welding at high speed, it is necessary to move the welding base material or electrode at high speed, and the arc state deviates from the state that matches the welding conditions at that time due to changes in the surrounding environment of the arc or inertia. There was a problem.

Therefore, in order to correct the deviation of the arc, the applicant previously proposed in Japanese Patent Laid-Open No. 62-286674 that the arc of magnet is corrected by utilizing the magnetism of a magnet that moves integrally with the electrode. did. The above-described arc correction is performed at high speed continuous welding by constantly directing the arc to the welding site by the magnetic action of a pair of magnets of N pole and S pole arranged point-symmetrically with respect to the center of the arc. The arc state at that time was kept in an optimum state, and the control was performed mechanically.

[Problems to be Solved by the Invention]

According to the above-mentioned conventional technique, it is possible to correct the arc condition during high-speed welding to keep it in an optimum state, but when trying to control the arc condition more positively according to various welding conditions, It is necessary to mechanically move the pair of magnets back and forth and to the left and right, and to rotate around the electrodes, which requires time and effort, and when it is necessary to respond to minute changes in welding conditions during welding work. However, since the pair of magnets are mechanically moved or rotated, the control is delayed from the actual change of the welding conditions, and the welding accuracy cannot be made sufficient.

[Object of the Invention]

Therefore, the object of the present invention is to solve the problems of the conventional techniques as described above, the actual state of the arc during high-speed welding by TIG welding the optimum reference state according to the welding conditions at that time. The present invention is to provide an automatic arc control method in TIG welding in which the control can be performed instantaneously and accurately, and sufficient welding accuracy can be obtained.

[Means for solving the problem]

In order to achieve the above object, the present invention has the following technical means. That is, to explain using the reference numerals used in the accompanying drawings corresponding to the embodiments, the non-magnetic welding base material 1 is an anode, the electrode rod 3 is a cathode, or the non-magnetic welding base material 1 is a cathode, an electrode rod. 3 serves as an anode, and a high-frequency current is generated between the electrode rod 3 and the base material 1 while ejecting an inert gas B for enclosing the arc A from the internal inert gas discharge space 5 of the ceramic cup 4 at the tip of the torch 2. The non-magnetic welding base material 1 is TIGed by the DC arc A generated by supplying power.
As a control means for welding and controlling the state of the arc A, TIG performed by using a group of a pair of magnets 6 of N pole and S pole symmetrically arranged with respect to the center of the arc A. In the method of controlling the arc in welding; the group of the pair of magnets 6 is a group of electromagnetic coil magnets that can be excited and demagnetized, and the coordinates developed in a plane for detecting the light generated from the arc A. The actual state 23 'of the arc A at the time of welding is provided by the optical detection means 8 for the arc arranged for each
Is detected, and the actual state 23 'of the arc A is compared with the reference state 23 of the arc corresponding to the state where the center of the arc A and the center of the electrode rod 3 are coincident with each other. In TIG welding, which is characterized in that the actual state 23 ′ of the arc A is variably controlled so as to match the reference state 23 by selectively exciting and deactivating each magnet 6 of the pair of magnets 6. This is the control method of the arc in the.

[Action]

Since the present invention comprises the above technical means, the actual state 23 'of the arc A is detected by the optical detecting means 8 arranged for each coordinate developed in the plane during the high-speed welding by TIG welding, and the actual state 23' is detected. ′ Is compared with the reference state 23 of the arc A in which the center of the arc A and the center of the electrode rod 3 coincide with each other, and a pair of magnets composed of electromagnetic coil magnets provided around the arc A by a predetermined program. The magnets 6 of the six groups are selectively excited, demagnetized, or the strength of the magnetic field is adjusted to change the magnetic action on the arc A, so that the state of the arc A can be controlled to match the reference state 23.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 to 4, the TIG welding apparatus of the present invention is
The torch 2 comprises a torch 2, a magnet mounting coordinate board 7 and an optical detecting means 8. The torch 2 has an electrode rod 3, a ceramic cup 4 which is hardly affected by magnetic force, and an inert gas discharge space 5 formed between them. The cathode side or the anode side of the power source 18 is connected to the electrode rod 3 so that the electrode rod 3 serves as a cathode or an anode. At the time of welding, the inert gas discharge space 5
Further, the inert gas B for enclosing the arc A is discharged. A plurality of pairs of N-pole and S-pole magnets 6 are arranged around the arc A on the magnet mounting coordinate board 7.
Moreover, the pair of magnets 6 is an electromagnetic coil magnet that can be excited and demagnetized and can change the polarity and the strength of the magnetic field. The polarity and the strength and weakness of the magnetic field are determined according to the state of the arc A, and are excited and demagnetized. The optical detecting means 8 includes an optical fiber mounting coordinate board 9 disposed below the magnet mounting coordinate board 7 and the optical fiber mounting coordinate board 9 described above.
The optical fiber mounting hole 21 provided with a predetermined coordinate arrangement (in this embodiment, the intersections of the concentric circles L _{1 to} L ₄ and the line segments D _{1 to} D ₁₂ that divide the concentric circle into 12 equal parts are predetermined coordinates). The optical fiber 10 disposed in the optical fiber 10, and the photosensor 11 for converting the analog quantity introduced into the optical fiber 10 into an electric quantity, the photocoupler 12 for cutting high frequency components and noise from the electric quantity, and the signal thereof. An input / output device 14 for inputting / outputting to / from the control part 13 and a signal from the input / output device 14 are judged, and the control part 13 for controlling the device is constituted to detect the state of the arc A during welding, The photo sensor 11, the photo coupler 12, the control unit 13, and the input / output device 14 are
It is surrounded by a shield 19 that blocks high frequency waves during TIG welding, and prevents malfunction of the device due to noise. Moreover, the optical fiber 10 has an optical fiber mounting hole 21.
Since it is arranged with a gap 22 left in it, it is possible to prevent the scattered light of the light generated by the arc A.
The state of can be detected. In addition, since the light generated from the arc A is very strong, it is not necessary to provide a lens or the like for condensing at the tip of the optical fiber. At the time of welding, the non-magnetic welding base metal 1 moves relative to the electrode rod 3 in the direction of the arrow M in the figure and is welded. Moreover, the non-magnetic welding base metal 1 and the electrode rod 3 are Each is connected to a power supply 18.
The power source 18 is a direct current power source and can supply a high frequency current by superimposing it on the high frequency current.

Now, the control of the group of electromagnetic coil magnets 6 which can be excited and demagnetized and which can change the polarity and the strength of the magnetic field will be described.

The inner reference state of the state of arc A is determined. For example, arc A
The state of the arc A in which the center of the arc and the center of the electromagnetic rod 3 coincide with each other is referred to as a reference state 23. On the other hand, the actual arc state when the non-magnetic welding base material 1 moves may deviate from the reference state 23. Let that state be the actual state 23 'of arc A. Then, during welding, the light generated from the arc A in the actual state 23 'is introduced by each optical fiber 10 and then converted into an analog quantity by the photosensor 11, whereby the state of the arc A in the actual state 23' is controlled. Is input to. Then, the control unit 13 compares the reference state 23 of the arc A with the actual state 23 'of the arc A, and the deviation is recognized. Under the control of the control unit 13 according to a program predetermined by the deviation value, the plurality of groups of electromagnetic coil magnets 6 are selectively excited or demagnetized, the polarity is changed, and the magnetic field strength is controlled. The actual state 23 'of the arc A is controlled so as to coincide with the reference state 23 of the arc A.
An example of this control example will be described later in a usage example.

Next, a usage example will be described based on the above configuration.

By supplying DC and high-frequency current from the power source 18 to the non-magnetic welding base material 1 and the electrode rod 3 in an overlapping manner, an arc A is generated from the tip 20 of the electrode rod 3 and the non-magnetic welding base material 1 At this time, the non-magnetic welding base material 1 can be continuously welded by moving the non-magnetic welding base material 1 in the direction of the arrow M in the figure. And the ceramic cup 4 at the tip of the torch 2
An inert gas B for enclosing the arc A is ejected from the inner inert gas discharge space 5.

In the above-mentioned welding operation, the arc A is changed by the change of the situation around the arc A generated when the non-magnetic welding base material 1 moves.
Becomes a reference state 23 according to the welding conditions at that time (actual state 23 '(Fig. 5 (B)) which is out of the state shown in Fig. 5 (A). Optical fiber mounting coordinate board 9 provided below the arc so as to surround the arc A
The light generated from the arc A is introduced by each optical fiber 10 provided in a predetermined coordinate arrangement (L ₁ D ₁ , L ₁ D ₂ , ... L _n D _n ) to the arc A by the photosensor 11. The generated analog quantity of light is converted into an electric quantity, the high frequency component and noise in the signal are removed by passing through the photocoupler 12, and the arc A in the control unit 13 is passed through the input / output device 14.
Recognize the actual state 23 '. That recognition of actual state 23 'of the arc A is L ₁ D _1, the intensity of each arc light introduced from the position of ~L _n D _n, is input to the controller 13, compare the intensity of each arc light It is obtained by calculating the position of the center of the arc of the actual state 23 'by calculation. Shows a case of recognizing the position 24 of the arc center of the actual state 23 'of the arc A at coordinates L _2, D ₁ in the present embodiment. Then, the arc A is controlled based on the deviation between the reference state 23 and the actual state 23 'of the arc A. For example, the state of the arc A as a reference
In order to set 23
A virtual line segment 15 connecting (L ₂ , D ₁ ) and the center of the reference state 23 of the arc A is obtained, and a virtual line segment orthogonal to the virtual line segment 15 and passing through the center of the reference state 23 of the arc A Ask for 16.
Then, a pair of magnets 6 provided at positions corresponding to the virtual line segment 16 are excited to generate a magnetic force line C around the arc A, and the magnetic action causes the arc A to be in the reference state 23 (see FIG. )) Can be. At this time, the polarities and strengths of the pair of magnets 6 are based on a program predetermined according to the coordinates of the displaced position 24, and the polarity is controlled by switching SW ₁ by the control unit 13. Excitation / demagnetization is performed by opening / closing SW _{2 to} SW ₇ , and the magnetic field lines are controlled by changing the strength of the current. By performing the above operation automatically during the welding of the welding base material 1, it is possible to maintain the state of the arc A at the reference state, which enables more accurate welding and control of the arc A. Since a mechanical operation is not required and only an electrical operation is performed, control delay is unlikely to occur. Further, since the program for controlling the arc can incorporate empirical factors corresponding to various conditions during actual welding, more accurate welding is possible.

FIG. 6 shows another example of the actual state 23 'of the arc A. In this case, the same control as described above is performed.

〔The invention's effect〕

As described in detail above, the present invention has the following effects. That is, according to claim 1, the arc A at the time of TIG welding is used.
Is detected by the optical detecting means 8 of the actual state of the arc, and a pair of magnet groups provided around the arc is excited and demagnetized by a program that is algorithmized according to the actual state of the arc at that time, thereby causing the magnetic field lines to the arc. By applying a force, the actual state of the arc can be controlled to the reference state of the arc, and at this time, no mechanical action is required and the control is performed only by the electrical action, so control is performed from detection of the actual state of the arc. Since it takes very little time to perform welding, accurate welding is possible, and since it is automatically controlled by a program that has been algorithmized beforehand, accurate control is possible and active control according to various welding conditions is possible. It is possible to provide a means for controlling the arc in TIG welding that enables the above. According to claim 2, the center position of the arc in the actual state is detected, the center position is orthogonal to the virtual line segment passing through the center of the reference state of the arc, and the center of the reference state of the arc is passed. Since the arc state is controlled to the reference state by exciting a pair of magnets arranged on the virtual line segment, good welding accuracy can be obtained without requiring complicated control. is there. Moreover, since an optical fiber, a photosensor, a photocoupler, an input / output device, and a control unit are used as the optical detection means, the state of the arc captured as light can be recognized as an electric quantity by the photosensor, and the high frequency component is removed by the photocoupler. Since it is possible to obtain more accurate information on the state of the arc, it is possible to improve the welding accuracy and at the same time to lengthen the optical fiber, it is possible to move away precision equipment such as the control unit from the welding site, The control is performed more safely. Furthermore, since the polarities of the pair of magnets and the strength of the magnetic field can be changed alternately, a wider range of control is possible.

[Brief description of drawings]

The attached drawings show an embodiment of the present invention, and FIG.
Sectional drawing which shows the structure of the principal part of a welding apparatus, FIG. 2 is the top view which follows the XX 'line in FIG. 1, FIG. 3 is the top view which follows the YY' line in FIG. FIG. 5 is a configuration diagram showing the configuration of the optical detection means, FIGS. 5 (A) to 5 (C) show an arc control method, and FIG. 5 (A) is a diagram showing an arc reference state. FIG. 5 (B) is a diagram showing the actual state of the arc, and FIG. 5 (C).
Shows a diagram when the state of the arc is controlled, and FIG. 6 is a diagram showing another example. In the drawing, reference numeral A ... arc B ... inert gas C ... magnetic field line 1 ... non-magnetic welding base material 2 ... torch 3 ... electrode rod 4 ... ceramic cup 5 ... inert gas discharge space 6 ... A pair of magnets 7 ... Magnet mounting coordinate board 8 ... Optical detection means 9 ... Optical fiber mounting coordinate board 10 ... Optical fiber 11 ... Photo sensor 12 ... Photo coupler 13 ... Control unit 14 ... I / O device 15 , 16 ... Virtual line segment 18A ... Welding power source 18B ... Excitation power source respectively.

Claims (2)

[Claims] 1. A non-magnetic welding base material 1 is an anode and an electrode rod 3 is a cathode, or a non-magnetic welding base material 1 is a cathode and an electrode rod 3.
And the ceramic cup 4 at the tip of the torch 2.
Non-magnetic welding by the direct current arc A generated by supplying high frequency current between the electrode rod 3 and the base material 1 while ejecting the inert gas B for wrapping the arc A from the inner inert gas discharge space 5 As a control means for TIG welding the base material 1 and controlling the state of the arc A, a group of a pair of magnets 6 having N and S poles symmetrically arranged with respect to the center of the arc A. In a method for controlling an arc in TIG welding performed by using a magnet, the group of the pair of magnets 6 is a group of electromagnetic coil magnets that can be excited and demagnetized, and is a plane for detecting the light generated from the arc A. The actual state 23 'of the arc A at the time of welding is obtained by the optical detection means 8 of the arc arranged for each coordinate that has been developed.
Is detected, and the actual state 23 'of the arc A is compared with the reference state 23 of the arc corresponding to the state where the center of the arc A and the center of the electrode rod 3 are coincident with each other. In TIG welding, which is characterized in that the actual state 23 ′ of the arc A is variably controlled so as to match the reference state 23 by selectively exciting and deactivating each magnet 6 of the pair of magnets 6. Control method in arc. 2. The control of the arc A is performed by an optical detecting means 8
Then, the coordinates corresponding to the center 24 of the arc A in the actual state 23 'are obtained, and the center of the arc A in the reference state 23 is orthogonal to the virtual line segment 15 connecting the coordinates and the center of the arc A in the reference state 23. The magnetizing process is performed by exciting the pair of magnets 6 arranged on a virtual line segment 16 passing therethrough.
Arc control method in TIG welding.