JPH0259033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacitor discharge type stud welding method and an apparatus therefor, in which a capacitor is charged with an electric charge and the electric charge is mainly used as welding energy.

[Conventional technology]

The conventional capacitor discharge type welding machine 10 has a first
As shown in the figure, a thyristor stack 12 is connected to the secondary side of a power transformer 11 to create a charging circuit 13.
, and charged a capacitor 15 connected in series to a reactor 14.

The capacitor discharge stud welding method using the capacitor discharge welding machine 10 is as follows:
First, the capacitor 15 is charged to a predetermined voltage by the charging circuit 13, and the thyristor 16 is turned on in response to a predetermined signal. The charge in the capacitor 15 is instantaneously discharged, and the stud material 18 is connected to the workpiece 1
It was welded to 9.

[Problem that the invention seeks to solve]

However, in the welding method using the conventional capacitor discharge welding machine 10, the stud material 18 is pressed against the workpiece 19 at a predetermined pressure, and the charge in the capacitor is discharged to generate an arc. , the welded part is melted, but since the stud material 18 is constantly pressed, the arc ends in a short time, and the stud material 18 and the object to be welded 19 are melted.
The problem was that only the surface of the material was melted, and the penetration was relatively shallow.

Therefore, in the case of a pipe made of stainless steel, which has poor heat conduction throughout the metal and has a curved surface, only the surface melts into a curved shape, making it difficult to completely weld the stud material 18.

Furthermore, in the conventional capacitor discharge type stud welding method, the stud material 18 is attached to the workpiece 1.
Since the capacitor is discharged while pressing 9, the welding conditions change depending on the time constant of the reactor 14 and the entire circuit, as well as adjustment of the spring force, etc. Once the circuit constant is selected, subsequent changes cannot be made. It has been difficult to perform stud welding reliably in accordance with welding conditions that vary depending on the material and its shape.

On the other hand, in arc studs that use an AC or DC power source, an arc is generated continuously while the stud material is raised, and the stud material and workpiece are pressed while being sufficiently melted, so that the welding part is not melted. However, if the thickness of the object to be welded is thin, it may melt to the back side, creating a hole phenomenon, and there is a problem that it may become unusable.

Further, arc stud welding performed using an alternating current or direct current power source as described above has a problem in that the power input is large.

The present invention was made in view of these circumstances, and provides a capacitor discharge stud that requires only a small power input and has deeper penetration and welding strength than when using a conventional capacitor discharge welder. The purpose of this invention is to provide a welding method and device.

[Means to solve problems]

In the capacitor discharge type stud welding method according to the present invention, which meets the above objectives, the stud material is pressed against the workpiece and at the same time is slightly pulled up, a pilot arc current that maintains a small arc is applied, and then a plurality of charged capacitors are welded. The stud material is sequentially discharged to generate a main arc to melt the surface of the stud material and the object to be welded, and then the stud material is pressed against the object to be welded to weld the stud material to the object to be welded.

A capacitor discharge welding machine according to the present invention which achieves the above object includes a stud holding means for removing and freely holding the stud material, and an elevating means for lifting the stud holding means in a pressed state. A capacitor welding type stud welding machine comprising a power supply device for supplying a welding current to the stud holding means, a DC power supply device that causes a pilot arc current to flow through the power supply device at the same time as or slightly earlier than pulling up the stud material; It is divided into a plurality of capacitor groups connected to a charging circuit, each of which is provided with a switch that turns on the capacitor continuously.

Here, the DC power supply that flows the pilot arc current and the power supply of the charging circuit that charges the divided capacitors may be provided separately, but it is also possible to use a common power supply and take the pilot arc current from the charging circuit. be.

[Effect]

In the capacitor discharge type welding machine according to the present invention, the power supply that supplies power to the welded part of the stud material includes a DC power supply device that flows a pilot arc current, and a group of capacitors that are each provided with a switch that is continuously turned on. It is composed of. Therefore,
In the capacitor discharge type stud welding method using the capacitor discharge type welding machine, the stud holding means is pulled up by the lifting means at the same time as welding starts, and at the same time or a little before this, the pilot arc current is turned on by the DC power supply. The current flows to form a small arc to maintain continuity, and then the switches connected to the capacitor group are turned on continuously to discharge the charge in the capacitors.

By setting the capacity of the capacitor to a sufficient amount to allow the stud material to be welded, a large current will flow between the workpiece and the stud material, and the charge in the capacitor will turn into arc heat, causing the welded part to heat up. Since it is completely melted and the discharge time is long, the welding becomes deep. Next, stud welding is completed by operating the elevating means to press the stud material against the workpiece.

In this case, the pilot arc current is small and the power to charge the capacitor is small, so
Stud welding with deep penetration can be performed even with small power supply equipment.

〔Example〕

Next, an embodiment embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention.

Here, FIG. 1 is a wiring diagram showing a schematic circuit configuration of a capacitor discharge type welding machine according to an embodiment of the present invention, and FIG. 2 is a wiring diagram according to the present invention using the capacitor discharge type welding machine according to the above embodiment. 1 is a waveform diagram showing the operating state of the capacitor discharge type stud welding method, in which A shows the moving state of the stud material and B shows the waveform of the current flowing between the stud material and the workpiece.

As shown in the figure, in a capacitor discharge welding machine 20 according to an embodiment of the present invention, electric power supplied by a power transformer 21 is converted into DC by a thyristor stack 22, which is an example of a rectifier circuit. After being rectified by the reactor 24 and the diodes 25, 26, 27, 28, 29, the capacitors 30, 31, 32, 33, and 34 (hereinafter referred to as a capacitor group 35) are charged.

This capacitor 30, 31, 32, 33, 3
4 has thyristor 3, which is an example of a switch.
6, 37, 38, 39, and 40 are connected, and the output thereof is connected to a terminal 43 connected to a workpiece 41 by a cable 42.

On the other hand, the negative terminal side of the capacitor group 35 is connected to a stud welding gun 45 via a terminal 44.

The stud welding gun 45 is provided with stud holding means (not shown in full) for standing the stud material 46 at a predetermined position on the object to be welded, and elevating means for lifting the stud material together with the stud holding means a predetermined length.

To explain the above elevating means in more detail,
A magnetic body is attached to the holding means that holds the stud material 46 which is pressed with a predetermined pressure by a spring, and the magnetic body is pulled up a predetermined length (approximately 0 to 1.5 mm) by an electromagnet if necessary. It's getting old.

The transformer 47 is a power transformer that supplies power to the electromagnet, and has relay contacts (triac,
A switch 48 (which may be a switching means such as a transistor) turns the electromagnet on and off in response to a signal from a control device 49.

The thyristor 50 is connected to the connection between the diode 29 and the capacitor 34 via a limiting resistor 51, and if necessary, turns on the thyristor stack 22 and turns on the thyristor 50 to connect the stud material 46 and the thyristor 50. It is used as a power source to flow an initial current that causes a pilot arc to flow between the workpiece 41 and the workpiece 41.

Here, the capacitor 34 functions as a smoothing capacitor and smoothes the current converted to direct current by the thyristor stack 22. Also,
In the embodiment described above, the device for supplying the initial current is taken from the thyristor stack 22 for charging the capacitor group 35, but it is also possible to provide a separate rectifier circuit.

Next, the operation of the capacitor discharge type welding machine 10 according to the above embodiment will be explained, and the capacitor discharge type stud welding method according to the present invention will be explained in detail.

First, a predetermined signal is sent from the control device 49 to operate the thyristor stack 22 and charge the capacitor group 35 to a predetermined voltage.

Next, the stud material 46 is attached to the stud holding means of the stud welding gun 45, and the workpiece 41 is
Install it at the designated welding location. In this case, it is assumed that the stud material 46 is pressed against the workpiece 41 by a predetermined pressure by a spring built into the stud welding gun 45.

In this state, when the welding start switch provided on the stud welding gun 45 is pressed, the control device 4
9 is activated, the thyristor 50 and the thyristor stack 22 are turned on, and the stud material 46 is turned on.
A current flows between the welding object 41 and the workpiece 41 (p in FIG. 2B). In this case, first capacitor 3
Since the current charged at 4 flows, the current that initially rose will flow.

At the same time or with a slight delay, the relay contact 48 is made conductive and the electromagnet of the stud welding gun 45 is activated (q in FIG. 2A). As a result, the stud 46 rises a little (r in Fig. 2A), an initial current flows between the tip of the stud 46 and the workpiece 41, and the pilot arc flies (second s in Figure B).

When the stud material 46 has risen a predetermined length, the thyristors 36 to 40 are turned on in sequence to discharge the charges accumulated in the capacitor group 35 and cause a large current to flow (t in Fig. 2B). A main arc is generated to melt the lower part of the stud material 46 and the upper surface of the workpiece 41, and at this point the control device 49 is operated to cut the relay contact 48 and turn off the electromagnet (as shown in FIG. 2A). u), stud material 4
6 is pressed against the workpiece 41 by the force of the spring to complete welding.

In the above embodiment, the thyristor stack 2
After 2, a reactor 24 is installed to restrict the rapid current from flowing, but it can be omitted by using a thyristor element with an appropriate capacity, and the limiting resistor 21 can be omitted. It is also possible to use a reactor instead.

〔Effect of the invention〕

As is clear from the above description, in the capacitor discharge type stud welding method and device according to the present invention, the large welding current is generated by storing electric charge in a plurality of capacitor groups and then sequentially discharging the welding current. Therefore, the power capacity required by the welding machine is small.

In addition, since the pilot arc is pulled up a predetermined length and transferred to the main arc while flying, the energy stored in the capacitor group is fully utilized as heat, resulting in stud welding with deeper penetration than the conventional capacitor discharge type stud welding method. It became possible to weld.

Furthermore, since the capacitance of the switch that discharges the capacitor group and the capacitor connected to each switch can be selected as appropriate, it is possible to obtain a welding current waveform that corresponds to the object to be welded. It is now possible to select welding conditions according to the shape.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram showing a schematic circuit configuration of a capacitor discharge type welding machine according to an embodiment of the present invention, and FIG.
The figure is a waveform diagram showing the operating state of the capacitor discharge type stud welding method according to the present invention using the capacitor discharge type welding machine according to the above embodiment.
B shows the moving state of the stud material, B shows the waveform of the current flowing between the stud material and the workpiece,
FIG. 3 is a wiring diagram showing a schematic circuit configuration of a conventional capacitor discharge type welding machine. Explanation of symbols, 21... Power transformer, 22...
Thyristor stack, 35... Capacitor group, 36, 37, 38, 39, 40, 50... Thyristor (switch), 41... Welded object, 4
5... Gun for stud welding, 46... Stud material.

Claims (1)

[Claims] 1. Press the stud against the workpiece and at the same time pull it up a little to flow a pilot arc current that maintains a small arc, and then sequentially discharge a plurality of charged capacitors to generate a main arc. A capacitor discharge type stud welding method in which the surfaces of the stud material and the object to be welded are melted, and then the stud material is pressed against the object to be welded to weld the stud material to the object to be welded. 2. Capacitor welding type stud welding comprising a stud holding means for detachably holding the stud material, lifting means for pulling up the stud holding means in a pressed state, and a power supply device supplying welding current to the stud holding means. In the machine, the above power supply device consists of a DC power supply device that supplies a pilot arc current at the same time as or slightly earlier than when the stud material is pulled up, and a plurality of switches that are connected to a charging circuit and are each equipped with a switch that is sequentially turned on. A capacitor discharge type welding machine characterized by being divided into a capacitor group. 3. The capacitor discharge type welding machine according to claim 2, wherein the DC power supply device that flows the pilot arc current and the power supply of the charging circuit that charges the divided capacitors are common.