JP3003469B2 - AC arc welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC arc welding machine.

[0002]

2. Description of the Related Art A conventional AC arc welding machine is configured as shown in FIG. In FIG. 3, reference numeral 1 denotes a main circuit unit for supplying an AC output between the electrode 3 which is a non-consumable electrode and a base material 4 which is a work to be welded; 2 a control unit for controlling the main circuit unit 1; It is a detector. In the circuit configured as described above, the detection of arc generation between the electrode 3 and the base material 4 is performed by the insulated current detector 8. When an arc is generated between the electrode 3 and the base material 4 and an output current flows, the insulation type current detector 8
Sends a detection signal proportional to the output current to the control unit 2. This detection signal is subjected to full-wave rectification by the control unit 2, and when the detection signal subjected to full-wave rectification exceeds a preset threshold value, regardless of whether the output current is positive polarity or reverse polarity, arc generation detection is performed. The signal is sent to the subsequent control unit and used for various controls. This arc generation detecting method is widely used in conventional DC arc welding machines and AC arc welding machines.

[0003]

By employing the above-mentioned method, it is possible to detect both forward and reverse arcs while isolating the secondary output of the welding machine from the control unit.

However, since the current flowing between the electrode 3 and the base material 4 is detected by the insulated current detector 8, the insulated current detector 8 controls the control unit 2 when the current is small.
Becomes small, and it becomes difficult to determine the detection signal and the threshold value for detecting arc generation due to the influence of noise or the like. Therefore, it is necessary to increase the minimum current value of the welding machine to make it easier to determine the detection signal and the threshold value, or to separately add a current detector for small current.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an AC arc welding machine capable of detecting the occurrence of forward and reverse arcs with a simple circuit. is there.

[0006]

In order to solve the above-mentioned problems, an AC arc welding machine according to the present invention comprises a main circuit for supplying an AC output between an electrode and a base material, and a control circuit for controlling the main circuit.
A main circuit section between output terminals of the main circuit section.
With a threshold value between the no-load voltage of the part and the arc voltage
A directional constant voltage element is provided.
The light receiving portion of the AC signal photocoupler connected in series,
Arc generation detection circuit for sending an arc generation signal to the control unit
And the main circuit that supplies AC output between the electrode and the base material
And a control unit for controlling the main circuit unit.
Between the output terminal of the circuit section and the no-load voltage of the main circuit section,
Bidirectional constant-voltage element with threshold between peak voltage
And the AC signal connected in series to the bidirectional constant voltage element.
A light-emitting portion of a photocoupler for signal
The light receiving section of the photocoupler is connected to the control section .

[0007]

According to the above construction, if the output voltage between the electrode and the base material is equal to or lower than the threshold value, an arc generation detection signal is sent to the control circuit.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An AC arc welding machine according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an AC arc welding machine according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a main circuit unit for supplying an AC output between an electrode 3 which is a non-consumable electrode and a base material 4 which is a workpiece, 2 a control unit for controlling the main circuit unit 1, and 5 an output voltage. Bidirectional constant voltage element for determining the value,
Reference numeral 6 denotes an AC signal photocoupler that operates when the bidirectional constant-voltage element is turned on, and serves as an arc detection detector. Reference numeral 7 denotes a current-limiting resistor.

[0010] With this configuration, as shown in FIG. 2, first, that it has begun welding in order to perform welding at time T _0. Along with the welding start command, an output voltage having a preselected polarity is supplied between the output terminals. Base material 4 and electrode 3
Between until time T ₁ an arc is generated the output voltage is the no-load voltage V _1, the arcing time T ₁ subsequently comprising output voltage and arc voltage V _2. Wherein V ₁ and V ₁ was between V _2> V ₂
There is a relationship.

The threshold voltage V _{s of the} bidirectional constant voltage element 5
Is set to the value of V ₁ > V _s > V ₂ , the bidirectional constant voltage element 5 conducts when the output voltage is the no-load voltage V ₁ , and the circuit current flows from the bidirectional constant voltage element 5 to the limiting resistor. 7, the light flows into the light emitting section of the AC signal photocoupler 6, the light receiving section of the AC signal photocoupler 6 becomes conductive, and sends an arc non-generation signal to the control section 2. Arc becomes to the bidirectional constant-voltage element 5 is non-conductive if the output voltage and the arc voltage V ₂ occurs, the light receiving portion of the AC signal photocoupler 7 because the circuit current does not flow becomes non-conductive, the control The part 2 recognizes the signal as an arc generation signal.

That is, according to this embodiment, the arc generation is determined by the no-load voltage and the arc voltage, which have a relatively large difference between the small output current and the large output current. by the threshold voltage V _s of the constant voltage element 5, it is possible arcing detection in a wide range from a small current to a large current.

[0013]

As described above, according to the present invention, by providing the voltage detection means for determining the output voltage value between the output terminals, even if the output polarity is positive, the output polarity is reversed. Even if there is, arc detection can be easily detected from an output voltage value from a small output current to a large output current, which is extremely effective in practical use.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of an AC arc welding machine according to one embodiment of the present invention.

FIG. 2 is a timing chart showing the arc occurrence detection operation.

FIG. 3 is a circuit configuration diagram of a conventional AC arc welding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main circuit part which can switch output polarity 2 Control part 3 Electrode 4 Base material 5 Bidirectional constant voltage element 6 Photocoupler for AC signals 7 Limiting resistance

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-228323 (JP, A) JP-A-59-209481 (JP, A) JP-A-5-69135 (JP, A) JP-A-5-209135 69134 (JP, A) Japanese Utility Model Showa 57-56571 (JP, U) Japanese Patent Publication 50-15224 (JP, B1) Japanese Patent Publication 42-13189 (JP, B1) Japanese Patent Publication 50-27036 (JP, B1) JP-B-53-33534 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/073 H02M 9/00

Claims (2)

(57) [Claims] A main circuit for supplying an AC output between an electrode and a base material; and a control unit for controlling the main circuit.
The no-load voltage of the main circuit and the ground
And a bidirectional constant voltage element having a threshold between
And the AC connected in series to this bidirectional constant voltage element.
The light receiving part of the signal photocoupler is
An arc generation detection circuit that sends raw signals
AC arc welder that. 2. A main circuit section for supplying an AC output between an electrode and a base material, and a control section for controlling the main circuit section, wherein the main circuit section is connected between output terminals of the main circuit section. A bidirectional constant voltage element having a threshold between the load voltage and the arc voltage ,
A light emitting section of the AC signal photocoupler connected in series to the bidirectional constant voltage element is provided, and the AC signal photocoupler is provided.
An AC arc welding machine with the light receiving part of the plastic connected to the control part .