JP2001300759A - Device for detecting contact of electrode for tig welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the setting of a gap between an electrode and a base material before welding, to immediately detect an accidental contact between the electrode and the base material during the welding, and to enable its rapid recovery. SOLUTION: The device for detecting the contact of the electrode for TIG welding equipment, with which the joining part of the base material is welded with an arc discharge between the electrode rod EL and the base material M by using an inert gas, is formed by a monitoring circuit 1 for welding voltage, which detects the presence or absence of application of the welding voltage between the electrode rod EL and the base material M and a detecting circuit 2 for contact with which an alarm signal is generated at the time of contact by detecting the presence or absence of contact between the electrode rod EL and the base material M. The function of the monitoring circuit 1 for welding voltage is characterized by the fact that the circuit always makes detecting circuit 2 for contact operate during the time when the welding voltage is not applied, opens the detecting circuit 2 for contact when the electrode rod EL is not in contact with the base material M during the time when the welding voltage is applied, and generates the alarm signal by making the detecting circuit 2 for contact operate when the electrode rod EL and the base material M come in contact with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an automatic TIG.
Regarding the welding equipment, an alarm signal is generated when the base material and the electrode rod come into contact, thereby facilitating the setting of the gap between the electrode and the base material before the start of welding, and when the electrode rod comes into contact with the base material during welding. The torch travel can be stopped automatically and the welding arc can be stopped to prevent the occurrence of defective products.
The present invention relates to an electrode contact detection device of a TIG welding device capable of returning work in a short time.

[0002]

2. Description of the Related Art Generally, in the TIG welding method, a certain gap is set between a base material to be welded and an electrode rod, and a plasma arc is generated between the electrode rod and the base material while flowing out an inert gas. And the molten metal is cut off from the air by an inert gas,
This is an arc welding method in which the base material is melt-bonded by arc discharge.

FIG. 4 is a diagram showing a specific principle of the TIG welding method. The welding rod EL is fixed to the collet body CB, and the collet body CB is inserted into the torch T. The two base materials M ₁ and M ₂ are joined to each other using a filler rod FW.
The state of welding at C is shown. The electrode rod EL and the base material M (M ₁ , M ₂ ) are opposed to each other with a predetermined gap.

In welding, a welding voltage is applied such that the electrode rod EL is negative and the base material M (M ₁ , M ₂ ) is positive while flowing an inert gas, for example, argon gas in the direction of arrow I. I do. By applying this welding voltage, the electrode rod E
An arc A is generated between L and the base material M, and the base materials M ₁ and M ₂ are joined by this arc discharge.

In order to generate a stable arc in the TIG welding method, setting a gap between the base material M and the electrode rod EL is an extremely important factor. Conventionally, in order to set the gap, first, it is necessary to check that the tip of the electrode rod EL is in contact with the joint MC while visually observing the joint MC of the base materials M1 and M2 with an optical microscope. After confirming this, a method has been adopted in which the electrode bar is raised by a micrometer device by a certain distance corresponding to the gap.

In the TIG welding method, the electrode E
Contact between L and the base materials M ₁ and M ₂ must be avoided. When the tip of the electrode EL is in contact with the base material M _1, M _2, a short-circuit current to the welding voltage at the contact portion of the base material M _1, M ₂ and electrode EL is applied directly flow matrix by the short-circuit current This is because M ₁ , M ₂ and the electrode EL are damaged. In the past, when such a contact accident occurred, a skilled worker noticed the accident at an early stage and manually raised the welding torch or operated an emergency stop. Trouble occurred frequently.

[0007]

With respect to the setting of the gap between the base material and the electrode, the above optical method is based on the premise that the visual acuity of the operator is good. It becomes difficult. In particular, the tip of the electrode rod is sharpened to form a stable constant arc, and considerable skill is required to confirm that the extremely thin tip is in contact with the base material, resulting in poor productivity. Was causing it.

[0008] In addition, regarding a contact accident between a base material and an electrode during welding, if a welding operator judges an abnormality in welding early and shuts off the welding voltage, it takes a considerable time to shut off. The speed of human judgment is slow, the damage of the base material and the electrodes is widened before the switch is turned off, and the economic loss and the time loss for repair tend to be enormous.

Accordingly, it is an object of the present invention to provide a TIG which facilitates setting of a gap between an electrode and a base material before the start of welding, and enables quick repair by immediately detecting a contact accident between the electrode and the base material during welding. An object of the present invention is to provide an electrode contact detection device for a welding machine.

[0010]

According to a first aspect of the present invention, there is provided a TIG welding apparatus for welding a joint of a base material by an arc discharge between the electrode bar and the base material using an inert gas. A welding voltage monitoring circuit for detecting the presence or absence of application of a welding voltage during the welding, and a contact detection circuit for detecting the presence or absence of contact between the electrode rod and the base material and generating an alarm signal upon contact; The function of is to always operate the contact detection circuit when no welding voltage is applied, and to cut off the contact detection circuit when the electrode rod is not in contact with the base material when the welding voltage is applied, so that the electrode rod and the base material come into contact with each other. An electrode contact detection device for a TIG welding device, wherein an alarm signal is generated by activating a contact detection circuit when the detection is performed.

According to a second aspect of the present invention, the welding voltage monitoring circuit comprises a comparator for comparing the welding voltage with a monitoring reference voltage, and a relay that is turned on and off by the output of the comparator. The T according to claim 1, wherein the detection circuit is shut off, and when the electrode rod comes into contact with the base material, the contact detection circuit is reset by a relay.
This is an electrode contact detection device of the IG welding device.

According to a third aspect of the present invention, the contact detection circuit comprises:
A detection power supply for applying a detection voltage, a comparator for comparing the detection voltage with a detection reference voltage when the electrode rod and the base material come into contact with each other, and a relay intermittently operated by the output of the comparator. 3. The T according to claim 1, wherein the relay is activated by the contact to generate an alarm signal.
This is an electrode contact detection device of the IG welding device.

According to a fourth aspect of the present invention, there is provided an electrode contact detecting device for a TIG welding apparatus according to the first, second or third aspect, wherein a high-frequency attenuation filter is interposed between the electrode rod and the base material and the welding voltage monitoring circuit. is there.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a TIG welding apparatus provided with an electrode contact detecting device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of a first embodiment of a TIG welding device provided with an electrode contact detection device according to the present invention. This TIG welding apparatus employs an arc start method using an external high frequency. The TIG welding device includes a welding voltage supply circuit 3, a torch T loaded with an electrode rod EL, a power supply circuit 4, and an electrode contact detection device C.
The electrode rods EL are arranged at a predetermined distance from the base material M. The electrode contact detection device C according to the present invention includes a high frequency filter F, a welding voltage monitoring circuit 1, and a contact detection circuit 2.

The welding voltage supply circuit 3 comprises a welding power source WE, a relay RY ₃ , a switch SW, and normally open contacts P ₃₁ and P ₃₂ . When exciting the relay RY ₃ closes the switch SW, the normally open contacts P _31, P ₃₂ is the welding voltage closed is supplied between the electrode rod EL and the base material M. When opening the switch SW relay RY ₃ is deenergized, the normally open contacts P _31, P ₃₂ is opened, the welding voltage is cut off.

The high frequency filter F is constituted by an LC filter, and prevents high frequency from entering a subsequent circuit. The cause of the high frequency is considered to be an external high frequency introduced for igniting the arc or a discharge during the generation of the arc. However, the high frequency is cut off by the filter F, and the electrode contact detection device C is disturbed by the high frequency. Never.

The welding voltage monitoring circuit 1 includes resistors R ₀ and R ₁ , high-voltage diodes D ₁₁ and D ₁₂ , a monitoring reference power supply Er ₁ for providing a monitoring reference potential, a comparator C ₁ , a relay RY ₁ and a normally closed contact P ₁₁ , and it is configured from the P _12. When point A becomes a high potential exceeding the monitoring reference potential, the output of the comparator C ₁ becomes a high level, energizing the relay RY _1. With this excitation, the normally closed contacts P ₁₁ and P ₁₂ are opened. Conversely, when the point A becomes a low potential, the relay RY ₁ is deenergized, the normally closed contact P _11, P ₁₂ is closed.

The contact detection circuit 2 includes a resistor R ₂ , a detection reference power supply Er ₂ for providing a detection reference potential, a comparator C ₂ , a relay R
It comprises Y ₂ , a detection power supply E ₂ for providing a detection voltage, a normally open contact P _2, and an alarm circuit AL. When the point B becomes a high potential exceeding the detection reference voltage, the output of the comparator C ₂ becomes a high level, to excite the relay RY _2. Normally open contact P ₂ by the excitation is closed, the alarm circuit AL generates an alarm signal. Conversely, when the point B is low potential, the relay RY ₂ is deenergized, the normally open contact P ₂ is opened by the alarm circuit AL stops generating the alarm signal.

The power supply circuit 4 includes an AC power supply AC and a noise filter.
NF, rectifying diode D, D _1, D ₂ and a smoothing circuit EC, EC _1,
Consists of EC ₂ . The smoothing circuits EC, EC ₁ and EC ₂ are, for example, R
It is composed of a C circuit and a three-terminal regulator circuit, etc.
And supplies the DC voltage V _cc, the V _cc1, V _cc2 to each circuit of the.

Next, the operation of the TIG welding machine will be described. This operation is of two types, and will be described separately for the operation before the start of welding and the operation during welding. First, before starting welding, the gap is adjusted so that the tip of the welding rod EL is separated from the base material M by a predetermined distance in order to generate a good arc discharge.

When the switch SW is turned off, the normally open contact P ₃₁ ,
Left open the P _32, keep blocked welding power WE. In this state, the electrode rod EL is lowered until it comes into contact with the base material M. When the electrode rod EL and the base material M are not in contact with each other, the detection voltage E
_2, the resistor R ₀ is pulled up, the potential at the point A becomes a high level, the normally closed contact P ₁₁ by the excitation of the relay RY _1, P
₁₂ is released. Accordingly, the relay RY ₂ is demagnetized point B becomes a low potential, the normally open contact P ₂ is the alarm circuit AL at left open is not activated.

The electrode rod EL descends and comes into contact with the base material M.
And the point A becomes low potential and the relay RY ₁Is demagnetized and normally closed
Contact P₁₁, P₁₂Is closed. This closure causes the
Pressure E_TwoIs applied to the point B via the contact portion, and the point B is
It becomes the potential and the relay RY_TwoTo excite. Therefore, normally open contact
Point P_TwoIs closed and the alarm circuit AL
Occurs.

There are various forms of the alarm signal. Here, an alarm sound is used. Upon hearing the alarm sound, the operator knows that the electrode bar EL has come into contact with the base material M, and stops lowering the electrode bar EL. When the electrode bar EL is raised by a predetermined distance from this position by a micrometer device (not shown), the gap between the electrode bar EL and the base material M can be finely adjusted to a predetermined value.

Next, when the switch SW is turned on, the normally open contacts P ₃₁ and P ₃₂ are closed, a welding power source WE is connected between the electrode bar EL and the base material M, and a welding voltage is applied between the two. . In this state, an external high frequency is applied to the gap between the electrode rod EL and the base material M to start an arc discharge between them.
The base material M is welded by stable arc discharge.

During welding, if the electrode rod EL and the base material M are not in contact with each other, the welding voltage acts on the resistance R ₀ and keeps the point A at a high potential. Accordingly, the relay RY ₁ is energized, normally closed contact P _11, P ₁₂ is held open, contact detection circuit 2 becomes a cut-off state, the alarm signal is not generated.

During welding, the electrode rod EL comes into contact with the base material M.
And the electrode A and the base material M are short-circuited, so that the point A
Changes to Therefore, the relay RY₁Is demagnetized and normally closed
Contact P₁₁, P₁₂Is closed and the contact detection circuit 2 is in the operating state.
become. That is, the detection voltage E _TwoMakes point B high potential
Relay RY_TwoIs excited. Normally open by this excitation
Contact P_TwoIs closed and the alarm circuit AL
Signal and inform the worker of the contact between the electrode rod EL and the base material M
I do.

The alarm sound causes the operator to operate the electrode rod E.
Knows that L has contacted the base material M, and immediately switches S
W is turned off to shut off the welding power source WE. As a result, damage to the electrode rod EL and the base material M can be prevented. Further, if the circuit configuration is such that the switch SW is automatically turned off by the alarm signal, the welding power source WE can be cut off at high speed, and the electrode rod EL and the base material M can be kept intact.

FIG. 2 is a schematic configuration diagram of a second embodiment of a TIG welding apparatus in which the electrode contact detection device according to the present invention is arranged. This TIG welding apparatus differs from the first embodiment in that it employs an arc start method by contact.

The electrode EL is brought into contact with the base material M in response to the generation of an alarm signal from the electrode contact detection device C. Switch SW
The turned on to energize the relay RY _3, normally open contacts P _31, P ₃₂
To close. By this closing, a welding voltage is applied between the electrode EL and the base material M. With the voltage applied, the electrode EL is raised by a predetermined distance by the micrometer device. At the moment when the electrode EL is separated from the base material M, an arc discharge starts between the electrode EL and the base material M. The contact between the electrode EL and the base material M during welding is constantly monitored by the electrode contact detection device C.

FIG. 3 is a schematic configuration diagram of a third embodiment of a TIG welding apparatus in which the electrode contact detection device according to the present invention is arranged. This TIG welding machine differs from the first embodiment in that it employs an arc start method by applying a high voltage power supply.

First, the electrode EL is detected by the electrode contact detecting device C.
The gap between the base material M and the base material M is adjusted. Then, exciting the relay RY ₃ by turning on the switch SW, closing the normally open contact P _31, P _32. Next, the high voltage power supply HE is connected between the electrode EL and the base material M by the arc start circuit AS, and an arc is generated between the two. After the arc start, the high voltage power supply HE is cut off by the arc start circuit AS, and the welding power supply WE is connected. The contact between the electrode EL and the base material M during welding is constantly monitored by the electrode contact detection device C. A diode D ₃ is to prevent the high voltage power supply HE is applied to the welding power source WE.

The present invention is not limited to the above-described embodiment, but includes various modifications and design changes within the technical scope thereof without departing from the technical concept of the present invention.

[0033]

According to the first aspect of the present invention, the gap between the electrode and the base material can be easily set before the start of welding.
In addition, a contact accident between the electrode and the base material during welding can be immediately detected to realize quick restoration.

According to the second aspect of the present invention, the welding voltage monitoring circuit can be simply constituted by a comparator and a relay, and an inexpensive and practically useful electrode contact detecting device can be realized.

According to the third aspect of the present invention, the contact detection circuit can be simply constituted by the detection power source, the comparator and the relay, and a simple, inexpensive and practically useful electrode contact detection device can be realized.

According to the fourth aspect of the present invention, since the high frequency attenuation filter is interposed in the preceding stage of the welding voltage monitoring circuit,
An external high frequency for arc start or a high frequency in the arc can be prevented from being mixed into the electrode contact detection device, and the electrode contact can be detected stably. The present invention has excellent practical utility as described above.

[Brief description of the drawings]

FIG. 1 shows a TI in which an electrode contact detection device according to the present invention is arranged.
1 is an overall configuration diagram of a first embodiment of a G welding device.

FIG. 2 shows a TI in which an electrode contact detection device according to the present invention is arranged.
It is a schematic structure figure of a 2nd embodiment of a G welding device.

FIG. 3 shows a TI in which an electrode contact detection device according to the present invention is arranged.
It is a schematic structure figure of a 3rd embodiment of a G welding device.

FIG. 4 is a specific principle diagram of the TIG welding method.

[Explanation of symbols]

 A is arc, AL is alarm circuit, AC is AC power supply, A
S is an arc start circuit, C is an electrode contact detection device,
C₁, C_TwoIs a comparator, CB is a collet body, D,
D₁, D_Two, D_Three, D₁₁, D₁₂Is a diode, E is a sensing power
Source, E_TwoIs the detection power supply, Er₁Is the monitoring reference power supply, Er_TwoIs
Knowledge reference voltage, EC, EC₁, EC_TwoIs a smoothing circuit, EL is
Pole, F is high frequency attenuation filter, FW is filler rod, HE is
High voltage power supply, M, M₁, M_TwoIs a base material, N is a noise filter,
P₁₁, P₁₂Is a normally closed contact, P_Two, P₃₁, P_{Three Two}Is a normally open contact,
R₀, R₁, R_TwoIs the resistance, RY₁, RY_Two, RY_ThreeIs a relay,
SW is a switch, T is a torch, WE is a welding power source, 1 is a welding power source.
Contact voltage monitoring circuit, 2 is contact detection circuit, 3 is welding voltage supply
Circuit 4 is a power supply circuit.

Claims (4)

[Claims] In a TIG welding apparatus for welding a joint of a base material by an arc discharge between an electrode rod EL and a base material M using an inert gas, a welding voltage is applied between the electrode rod EL and the base material M. Voltage monitoring circuit 1 for detecting the presence or absence of
The welding voltage monitoring circuit 1 comprises a contact detection circuit 2 which detects the presence or absence of contact between the EL and the base material M and generates an alarm signal at the time of contact, and the function of the welding voltage monitoring circuit 1 is to constantly operate the contact detection circuit 2 when no welding voltage is applied. When the welding voltage is applied, the contact detection circuit 2 is cut off when the electrode rod EL is not in contact with the base material M, and the contact detection circuit 2 is operated when the electrode rod EL comes into contact with the base material M. An electrode contact detection device for a TIG welding device, wherein the electrode contact detection device generates an alarm signal. Wherein said welding voltage monitoring circuit 1 includes a comparator C ₁ for comparing the welding voltage and monitoring reference voltage consists relay RY ₁ Metropolitan intermittently by the output of the comparator C _1,
The relay RY ₁ upon application of the welding voltage blocking said contact detection circuit 2, the electrode rod EL is according to claim 1 for returning operating the contact detection circuit by the relay RY ₁ upon contact with the base material M of the TIG welder Electrode contact detection device. Wherein said contact detection circuit 2 includes a detection power source E ₂ of imparting a detection voltage, a comparator C which electrode rod EL and the base material M to compare the detection voltage and the detection reference voltage when contacted
₂ and the relay R intermittent by the output of this comparator C ₂
Consists Y ₂ Prefecture, relay RY ₂ by contact of the electrode rod EL and the base metal M
3. The electrode contact detection device for a TIG welding machine according to claim 1, wherein the device operates to generate an alarm signal. 4. The electrode contact detection device for a TIG welding machine according to claim 1, wherein a high-frequency attenuation filter F is interposed between the electrode rod EL and the base material M and the welding voltage monitoring circuit 1.