JPH044977A - Power unit for stud welding - Google Patents

Abstract

PURPOSE:To perform suitable welding in accordance with material by comparing a detection signal of a current detector with at reference signal and feedback- controlling high-frequency switching so that the detection signal is coincident with the reference signal. CONSTITUTION:The current detector 37 detects a load current flowing through a stud 18 and base metal 19 based on DC for arc welding. A reference signal generation part 39 generates signals to change alternately to levels of a base period of a low current and a pulse period of a high current with a period set on the arc melting section of the stud 18 and the base metal 19 as the reference signal for controlling output. The detection signal of the current detector 37 is compared with the reference signal and a driving control part 30 feedback- controls high-frequency switching so that the detection signal is coincident with the reference signal. Consequently, the influence of variation at the power source side and the load side is prevented and stability of welding can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC stud welding power supply device used for stud welding using the arc welding method.

[Conventional technology]

Conventionally, a DC stud welding power supply device used for stud welding using the arc welding method is configured as shown in FIG. (2) AC input terminals (3a), (3b) and circuit breaker (4a).

(4b) to the primary winding (5a) of the power transformer (5).
).

The power transformer (5) is the main arc generator.
It has a secondary winding m (5b) and a tertiary winding m (5C) for pilot arc generation. 7
b) After full-wave rectification in the main arc rectifier circuit (8) with a bridge circuit configuration, the free-wheeling diode (9
), smoothing glue)/L/Qci to the power supply (
2) to the output terminals (lla) and (Ilb) of the output terminal (
llb) is supplied as a direct current for the main arc.

Also, the output of the tertiary winding (5C) is a diode (12a)
.

After full-wave rectification in the pilot arc rectifier circuit α, which has a mixed 71° diode circuit configuration with (12b) and cylindrical star (Llla), (J3b), the freewheeling diode (to),
Output terminal (lla
), (llb).

It is supplied as a direct current for the pilot arc with the output terminal (Ilb) being positive.

Soshite, + IJ star (7a), (7b) and (
+3a) and (+3b) are determined by the control circuit αη provided in the power supply device (2).

Driven by timer control.

That is, when planting the stud (G) of the welding gun on the base material α by arc welding, the stud side is erected in advance on the base material QIVL-4 as shown in Fig. 10(a). The trigger switch is turned on and fg contact is started.

(7) Based on i+J trigger gas inch on.

The control circuit port first connects the thyristor (13a), (+3b)
10 (b) to the stud (2) and the base material aqh.
) will supply a small capacity pilot DC current of several tens of meters as shown by the arrow line.

In this state, the stud) is pulled up and separated from the base material α9, and the pilot arc (Ap
) occurs.

Furthermore, after the occurrence of the pyro arc (Ap), the control circuit (37) switches to driving the cyrisks (7a) and (7b).

A large-capacity main arc direct current of several hundred to several) 000 A, as shown by the arrow line in FIG. 10(d), is supplied to the stud side and the base metal.

Stud side by direct current for this main arc.

A main arc (Am) is generated between the base metals α1, and the heat of this arc (Am) melts the base metal G1 and the stud arc.

Then, when the main arc (Am) continues for a certain period of time,
The stand (to) is pushed down in the direction of the base material (11) by the pressure of the gun coil of the melting gun, and the stud [phase] is attached to the base material a9 as shown in Fig. 1θ (e).

At this time, in the control circuit 7) is the stud (G), the base material α9
The driving of the thyristors (7a) and (7b) is stopped at a timing set so that the load current between them reaches an appropriate level for welding, and the DC supply from the output terminals (11a) and (Ilb) is gradually reduced. Stop.

Then, after the stud (to) is welded to the base material -, the stud (to) is removed from the welding gun, and the stud (to) is planted in the base material 03 as shown in Fig. 10(f). The fg connection ends.

In addition, thyristors (7a), (7b) and (+3a)
, (+3b), continuity of the load current is maintained by the diode (9) and αG.

Further, the polarity of the load current is set to be positive for the base material Ql so that melting can be easily performed.

[Problem to be solved by the invention]

In the case of the conventional stud welding power supply device (2) shown in FIG.
Alternatively, the 50 Hz alternating current is rectified to form direct current for the main arc and pilot arc as the direct current for arc welding, so the load current pulses at the commercial power frequency as shown in FIG. 11.

In this case, especially since there is no pulse change in the load current during arc melting due to the main arc (Am).

Poor arc concentration.

Moreover, since the base material α9 is always heated with a substantially constant amount of heat, the base material 01
Holes etc. occur.

Therefore, there is a problem in that good fg contact cannot be achieved depending on the material of the stud (end), the base material, the diameter of the stud (end), etc.

Also, power transformer (5), react/L/QQ, QQ
For example, large and heavy products for low frequency are used, and the DC capacity for one arc differs greatly.

Requires dedicated windings (5b) and (5c) for the main arc and pilot arc, rectifier circuit (8), α-column, reactor α0, AE, etc., resulting in a large and heavy device. be.

Furthermore, since the DC for both arcs is formed by directly rectifying commercial AC from the source, it is easily susceptible to fluctuations in the commercial AC power supply, and is susceptible to contact defects due to so-called power fluctuations, resulting in poor stability. (Reproducibility) Problems with poor reproducibility are also identified.

The present invention has a compact and lightweight configuration that improves the concentration of the arc during arc melting, and also allows for appropriate heat input control depending on the material of the stand and base material. It is an object of the present invention to provide a DC power supply device for stud welding, which allows extremely stable welding against side fluctuations.

[Means to solve the problem]

Input side rectifier.

an inverter section that converts the output of the input side rectifying section into high frequency alternating current by high frequency switching of a plurality of switching semiconductors and supplies it to the primary side of the high frequency transformer; and an inverter section that rectifies the output of the secondary side of the high frequency transformer to generate an arc. an output side rectifier for forming a direct current for welding; and the stud based on the direct current for arc welding.

A current detector detects the load current flowing through the base metal, and the stud serves as a reference signal for output control. and a reference signal generator that generates a signal whose level changes alternately.

Comparing the detection signal of the current detector and the reference signal,
and a drive control section that performs field control of the high frequency switching so that the detection signal matches the reference signal.

[For production]

In the case of the power supply device of the present invention configured as described above, after the AC power source such as a commercial AC power source is rectified by the input side rectifier,
The high frequency alternating current Kf is converted in the inverter section.

The high-frequency alternating current from the inverter section is output via a high-frequency transformer (1111) and is rectified by the rectifying section, converted into direct current for arc welding, and supplied between the stud and the base metal.

Because of this, a small, lightweight switching regulator circuit generates direct current for arc welding without distinguishing between pilot arc and main arc, as in the past.

Then, the high frequency switching of the inverter section is controlled by feedback control of the V-motion control section based on the detection signal of the current detector and the reference signal of the reference signal generation section so that the detection signal matches the reference signal.

At this time, due to the change in the level of the reference signal in the arc g-section, the load current in the arc melting section becomes a pulsed current that changes greatly at a frequency based on a set cycle.

The pulsed load current improves the concentration of the arc and controls the amount of heat input to the stud and the base metal by periodically increasing and decreasing it.

Therefore, it is necessary to set the period of the level change of the reference signal according to the stand, the material of the base material, etc.

Improved arc concentration allows for optimal welding depending on the material, etc.

Moreover, the high-frequency switching blade pack control prevents the effects of reaction on the power supply side and the load side with quick response control, improving welding stability.

[Tora example]

The east example will be explained with reference to FIGS. 1 to 8.

(1-addition example) First, a 1-addition example will be explained with reference to FIGS. 1 to 6.

As shown in Figure 1, a commercial AC power source (1) as an AC ffi power source is connected to the AC input terminal (1) of the power supply unit for stud welding.
21a), (21b) and circuit breakers (22a), (22b)
) is supplied to the rectifier circuit (c) of the input side rectifier @.

This rectifier circuit (c) is a rectifier diode (25a)
.

It is formed of bridge rectifier circuits (25b), (25c), and (25d), and rectifies the commercial AC power supply (1).

Then, the output of the rectifier circuit (c) is passed through the DC reactor/L/wire for rectification and the capacitor wire for smoothing to the full transistors (29a), (29b), (29c),
(29d).

Transistors (29a), ('29d), and
29b) and (29c) switch inversely to each other.

Then, high frequency alternating current is supplied to the primary winding N (32a) of the high frequency transformer (12) by high frequency switching of the transistors (29a) to (29d).

Furthermore, the high frequency alternating current of the secondary winding (32b) with center tap 7 of the high frequency transformer I3z is transmitted to the output 4AI rectifier (13+) rectifying diode (34a), (34
After full wave rectification in b), it is smoothed in reactor □□□,
Direct current for arc welding is created.

This DC is supplied between the stud (G) and the base material α) via the output terminals (36a) and (36b), and based on this supply, the load current flowing through the stud (G) and the base material G1 is It is detected by a current detector 3γ provided between the cathodes of the diodes (34a) and (34b) and the output terminal (36b).

Then, the detection signal Vd of the detector '31 according to the load current is
is supplied to the drive control signal error amplification circuit &'.

This amplifier circuit '18! The detection signal Vd is compared with the reference signal Vref for output control of the reference signal generating section i39'.

Based on this comparison, the error amplification circuit C (81 is the detection signal V
A signal corresponding to the deviation amount of d from the reference signal Vref is formed and supplied to the PWMi adjustment circuit t401.

The father adjustment circuit 14 (ll) forms a high-frequency drive control signal whose pulse width changes according to the amount of deviation.

Based on this drive control signal, the output circuit variably controls the on-periods of the transistors (29a) to (29d) in accordance with the amount of deviation.

Through this variable control, the load current is feedback-controlled so that the detection signal Vd becomes equal to the reference signal Vref.

The reference signal generating section is constructed as shown in FIG. 2, and the switch control circuit 1411 is triggered and activated in conjunction with the operation of the trigger switch of the FG gun.

This control @ 1 circuit 4] is based on the timer operation, and each welding interval T is controlled by the pilot section 0° from the start of fg contact until the pilot arc (Ap) in Fig. 1O (C) occurs. The arc gW!1 section (11) in which the stud [phase] and base material αO melt in the main arc (Am) of i), the same figure (
e) and (f) are time-divided into the joining section (+1+>) where the studs are joined to the base material α9 and planted.

Then, by gate processing of a plurality of counter pulses generated based on the timer operation, the switch control circuit'
41) generates an ON control signal for the switch (42a) in the pilot section (+), and in the arc melting section (ii), the switch (42
b) Alternately generating the ON control signals of (42c),
The junction section (IIi) generates an ON control signal for the K switch (42c).

Therefore, in the pilot section m, the switch (42a) is turned on as shown in FIG. 3(a), and the output of the pilot arc reference power source (44a) is switched on.

The signal is supplied to an operational amplifier circuit for buffer amplification via a resistor (451).

In addition, in the arc fg#lI section (11), Fig. 3 (C)
, fd), the switch (42b), (
42c) are turned on alternately.

Pulse period 1i5 (ta
), the output of the pulse current reference power supply (44b) is the switch (42b).

The signal is supplied to the operational amplifier circuit 146) via the resistor (45b).

During the base period (tb) when the switch (42c) is on, the output of the base current cycle fs power supply (44C) is
2C).

The signal is supplied to an operational amplifier circuit (46) via a resistor (45c).

Furthermore, in the joining section (iii'), the switch (42C) is turned on as shown in FIG. 3(C), and the reference power source (44
The output of C) is an operational amplifier circuit! 461.

In addition, (45d) in Fig. 2 is a resistor for voltage division, 147'
The decoy is a resistor for determining the gain and bias of the operational amplifier circuit.

Then, each reference power source (44a), (44b), (
44c), the operational amplifier circuit 146
As shown in FIG. 3(d), the reference signal Vref supplied from the error amplifier circuit (north) in FIG. 1 to the error amplifier circuit (north) in FIG.
11) Level Va.

Vb (Vo < Vb < Va) K changes alternately and reaches level vb in the junction section (iii).

Based on this level change of the reference signal Vref, the load current becomes low as shown in FIG. 4(a), and the pilot period (
i) A pilot arc (Ap) is generated.The arc is controlled to a constant current IO with a small capacity of about several dozen, and arc generation is performed stably.

Furthermore, the main arc (Am
) is generated, and a large-capacity pulse current Ia of several thousand to several hundred A is generated to input sufficient heat into the stud (g) and the base metal a9, and a base current of about several hundred A is generated to maintain the main arc (Am). The pulse changes alternately to Ib and Ib.

This pulse change in load current causes the main arc (Am
) improves the stiffness of the stud (to) and prevents deflection.
The main arc (Am) is concentrated at the bottom of the stud (
), the joint of base material Q'J is reliably and stably melted.

Moreover, the heat input state of the stud exposed base material a1 is controlled by alternating between heating based on the pulse current Ia and cooling based on the base current Ib, and the pulse current Ia corresponds to the conventional direct current supply for the main arc. Overheating caused by continuous supply of water is prevented.

To be sure of this, by setting the pulse period tal and base period tb to an appropriate period of heat input according to the material of the stud (G) and the base material 4, for example, even if the base material 09 is a thin plate, holes may occur. Good welding is achieved without any occurrence of this problem.

In addition, the welding section (i) immediately after the arc melting section (II)
In ii), the load current is maintained at a constant current of the base current Ib, and based on this constant current, the welding timing is determined within the welding section (iii) due to variations in mechanical properties such as the push-down mechanism of the gun coil of the TG implant gun. Even if the load current fluctuates, the load current is maintained at a current that allows stable bonding, and the stud (end) and base material α
9 is stably bonded.

By the way, the pulse change of the load current in the arc melting section (11) is determined by the reference signal Vr using the Deinoa switch (0).
By variable setting of the level change period of ef, it is also possible to set it to a higher frequency, for example, as shown in FIG. 4(b).

Then, based on the setting of the level change period of the reference signal, the load current change frequency of the arc melting section (11) is approximately several dozen to several tens of degrees depending on the material of the base material Q1. It is arbitrarily set variably within the range of i.

At this time, the higher the pulse change frequency becomes, the more concentrated the arc becomes.

”! To each v of the reference signal Vref, yL/Va, V
a, Vb c, 1 [variably set arbitrarily by the t-pressure capacitor of the power source (44a) to (44c), especially the power source (44b)
, (44c) by varying the voltage.

The arc fgM section f! ](ii) heat input control is -f
iF can be performed with high accuracy.

1 [source device (1) is formed by a so-called switching power supply, and the transistor (29) of the inverter section (c)
Due to the feedback control of high frequency switching in a) to (29d), the load current changes continuously, stably and accurately over a wide range according to the reference signal Vref, so that the DC for arc welding is The power supply transformer (5) is formed by a compact, lightweight, common If-direction circuit using a compact, lightweight high-frequency transformer 132' or the like.

Moreover, by high-frequency switching of the transistors (29a) to (29(1)), the load current can be corrected and controlled with good responsiveness to fluctuations in the commercial AC power supply (1) and arc length.
This prevents deterioration of the fg connection quality due to power supply fluctuations and arc erosion (load failure).

By the way, the inside of the inverter section etc. may be configured as shown in FIG. 5 or FIG. 6.

In the case of FIG. 5, the inverter section (C) is a switching semiconductor, and two transistors C (49a),
(49b) and U 2 fm LD:! +
(50a), (50b) (Formed with a D half-bridge configuration.

Also, in the case of Fig. 6, the inverter section G is in a constant state! −
Two transistors (51a) as a 7g and a half m body.

(51b) and 11i117) Thailand, t-do (52a)
, (52b) can be formed with a 26-forward configuration, and a high frequency transformer (3z is a primary winding (32a)' without a center tap).

It is formed by a secondary winding (32b)'.

(Other Examples) Next, other examples will be described with reference to FIGS. 7 and 8.

vinegar.

This generating section is formed by providing an integral smoothing capacitor in parallel with the gain setting resistor (47) of the operational amplifier circuit shown in FIG.

Then, due to the integral action across the capacitor, Fig. 8(a)
, the switch (42a) shown in (b) and (c),
The reference signal Vref based on the switching of (42b) and (42c) is made smooth to the extent that the rising and falling edges do not impair the pulse change of the load current, as shown in FIG. 4(d).

Based on the smoothing of the rising and falling edges of the reference signal Vref, the load current also changes as shown in FIG. 8(d), and the rising and falling edges are smoothed.

Therefore, noise such as arc sound especially in the arc melting section (11) where the load current changes in pulses is reduced compared to the case of FIG. 1, and the noise can also be reduced.

The structure of the driving/reducing part (1), the reference signal generating part 39, etc., and each section m, (ir), (o) of the reference signal Vref:
) levels etc. are not limited to one example.

〔Effect of the invention〕

Since the present invention is configured as described above, it achieves the effects described below.

AC power is converted to DC at the input side rectifier, this DC is converted to high frequency AC at the inverter, and the high frequency AC via the high frequency transformer is returned to DC at the output side rectifier to produce DC for arc welding. This direct current is supplied between the stud and the base metal.

The high-frequency switching of the inverter section is feedback-controlled via the drive control section so that the load current detection signal of the current detector matches the reference signal of the reference signal generation section, and the level of the reference signal changes during the arc melting section. Based on
Because the load current changed in a pulsed manner at a set period,
A single circuit with a small and lightweight switching power supply configuration can stably vary the load current over a wide range to form direct current for arc welding.

Also, based on the pulse change of the load current in the arc 4 section, it improves the concentration of the arc during melting and controls the heat input to achieve an appropriate fg according to the material of the base material, etc.
It is possible to make contact with

Moreover, based on the feed puncture control of high frequency switching, it is possible to prevent f-movement on the power supply side and the load side, thereby improving welding stability.

[Brief Description of the Drawings] Figures 1 to 8 show embodiments of the stud welding power supply device of the present invention, and Figure 1 shows 19! Example wiring diagram, Figure 2 is a detailed wiring diagram of a part of Figure 1, Figures 3 (a) to (d)
are shown in Fig. 2 (timing chart for operation explanation) and Fig. 4 (
a) and (b) are waveform diagrams of the load current in Figure 1, Figures 5 and 6 are connection diagrams of other examples of the inverter section, and Figure 7 is a part of details of another example. Connection diagram, No. 8
Figures (a) to (d) are timing charts for explaining the operation of Figure 7, Figure 9 is a connection diagram of the conventional example, and Figures 10 (a) to (
f) is a process explanatory diagram of stud welding, and FIG. 11 is a waveform diagram of the load current in FIG. 9. (1)...Commercial AC power supply, (to)...Stud, q9
・Base material. ...Input side rectifier section, @...Inverter section, ■...
Drive control section, (IZ...high frequency transformer, c113
1...Output side rectifier. Ll171...Current detector, (support) s, o9'...
・Reference signal generation section.

Claims (1)

[Claims] (1) In a stud welding power supply device that supplies DC for arc welding between a stud and a base metal, the input side rectifier section rectifies the AC power source, and the input side rectifier section uses high frequency switching of a plurality of switching semiconductors. an inverter section that converts the output of the high-frequency transformer into a high-frequency alternating current and supplies it to the primary side of the high-frequency transformer; an output-side rectifier section that rectifies the output of the secondary side of the high-frequency transformer to form the direct current for the arc welding; a current detector that detects the load current flowing through the stud and the base metal based on the DC for the arc welding; a reference signal generating section that generates a signal that alternately changes in level between a current base period and a large current pulse period, and compares a detection signal of the current detector with the reference signal, and compares the detection signal with the reference signal. 1. A power supply device for stud welding, comprising: a drive control section that feedback-controls the high frequency switching so as to match the above.