JPS63130276A - Tig welding method - Google Patents

Abstract

PURPOSE:To perform the appropriate welding by supplying an arc current in the TIG welding with binary levels with a prescribed period and making its low value level to a low current value of an area where the welding voltage rises to change heat input with a welding condition constant. CONSTITUTION:A welding source 1 is constituted of a DC power source 2, a semiconductor controlling element 3 to control an outputting state of the power source 2 to load and a current control circuit 4 to control the current of the element 3 and the power is outputted from the element 3 to a torch 7 and the TIG welding is performed between a W electrode 6 and base metal 5. And arc current waveform outputted from the welding source 1 at this time is made to an intermittent waveform and the current is of a rectangular wave with abt. 20-500Hz and the low value current value IB of abt. 0-50A is selected. As a result, although the change of the voltage in accordance with the change of the current is small in a current area (abt. 50-350A) used for the ordinary welding, it becomes high suddenly in the low current area (<= abt. 50A) and the arc voltage becomes high transiently and the average arc voltage becomes high. In this way, the depth of penetration can be changed without changing a bead shape and the appropriate welding is performed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a TIG welding method, and in particular, it is possible to increase the heat input to the base material while keeping the bead shape such as bead height and bead width constant. Regarding TIG welding method.

[Conventional technology]

In the TIG welding method, an arc is generated between a tungsten electrode and a base metal to create a molten pool, and an additive wire is inserted into this molten pool to perform welding.

Conventionally, in TIG welding, conditions such as current value, additive wire, welding speed, etc. are set depending on plate thickness, groove, etc., and the size of the weld bead is determined by these. Furthermore, the heat input to the base metal was controlled by changing the arc current and welding speed.

However, even if welding conditions are set to obtain suitable bead width and bead height, it is difficult to obtain optimal conditions when the amount of weld penetration is insufficient.

[Problem that the invention seeks to solve]

In the conventional TIG welding method, if the amount of welding into the base metal is insufficient under the conditions that an appropriate bead shape can be obtained,
If the arc current is increased or the welding speed is decreased in order to increase the amount of heat input, the bead height and bead width change, making it impossible to perform proper welding.

An object of the present invention is to provide a TIG welding method that can increase heat input to the base metal while keeping the bead shape constant.

[Means for solving problems]

In order to solve the above problems, the present invention creates a molten pool by an arc generated between a tungsten electrode and a base metal, and performs welding by inserting an additive wire into this molten pool.
In the IG welding method, an arc current is supplied at a binary level at a predetermined period, and the low level is set to a small current value in a region where the welding voltage increases.

[Effect]

According to the above means, if the arc current is made into a rectangular wave current with a predetermined cycle of 1tII, and the low value level is set to a value smaller than the normal welding current region, the average voltage can be increased even though the average current is constant. Therefore, heat input can be increased without changing the bead shape.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a circuit diagram showing a schematic configuration of a welding device that implements the method of the present invention, and FIG. 2 is an arc current waveform diagram obtained by the device shown in FIG.

The welding power source 1 includes a DC power source 2, a half-quad control element 3 that controls the output state of the power source 2 to a load, and a current control circuit 4 that controls the current of the element 3.

The positive output of the DC power supply 2 is connected to the base material 5, and the output of the semiconductor control element 3 is connected to a torch 7 having a tungsten electrode 6.

The arc current waveform output from the welding power source 1 can be arbitrarily set by the current control circuit 3, and for example, an intermittent waveform as shown in FIG. 2 can be output. In the example shown here, the current is a rectangular wave with a frequency of 20 to 500 tlz, and a low current value I.

is selected from 0 to 50A. The welding current is evaluated based on the average current, and this average current is used to adjust the high value current value (peak current value), or to adjust the low value current value 1. This can be changed by changing the energization period.

FIG. 3 is a static characteristic diagram of the arc with respect to the arc length. As is clear from this figure, in the current range used for normal welding (50-350A), the change in voltage due to the change in current is small, but in the small current range (50A or less), the voltage changes suddenly. There is. Therefore, when the current is periodically lowered to a low current range as shown in FIG. 2, the arc voltage becomes transiently high, and the average arc voltage becomes higher than when welding with a constant current.

That is, even if the average current of the arc is constant, the average voltage can be increased by using a pulse current as shown in FIG. This means that the welding heat input, that is, the penetration rate, can be controlled while the welding current, welding speed, etc. remain constant.

FIG. 4 is a comparison diagram showing the relationship between the average current and heat input of the conventional energization method (constant hot welding current) and the welding method of the present invention (pulsed current). The characteristic according to the present invention is indicated by O mark, and the current waveform as shown in Fig. 2 is IB#OA, and the period T of I2 is
, and T, the ratio of periods TB is TP : Ts = 1
: Comparison of the relationship between average current and heat input when it is set to 1.

FIG. 5 is a circuit diagram showing another example of the configuration of the welding power source 1.

The same reference numerals are used for the same parts as in FIG. , transistor, turn-off thyristor, etc.), and also connect the negative pole of the DC power supply 2 to the torch 7, which is then turned ON-OFF by the current control circuit 6.
A configuration is adopted in which a pulse current is generated by F control.

Such a configuration simplifies the configuration of the power supply. In addition, the current value during the low current period of the pulse is almost O
It is possible to lower it to.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to change the heat input while keeping the welding conditions such as the average welding current and welding speed constant. The penetration depth can be changed, allowing for proper welding.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a schematic configuration of a welding device that implements the method of the present invention, Fig. 2 is a diagram of the arc current waveform obtained by the device of Fig. 1, and Fig. 3 is a diagram of the static characteristics of the arc with respect to the arc length. , Fig. 4 is a comparison diagram showing the relationship between average current and heat input between the conventional energization method (constant welding current) and the welding method of the present invention (pulsed current), and Fig. 5 is a circuit showing another example of the welding device. It is a diagram. 1-----Welding power source, 2...--11-DC current, 3
--- Semiconductor control element, 4--- Current control circuit, 5-- Base material, 6-- Tungsten electrode, 7-
------・-Torch, 8--------High current switching element. Figure 1 Figure 2 Figure 3 First class (A) →

Claims (3)

[Claims] (1) In the TIG welding method, which creates a molten pool by an arc generated between a tungsten electrode and the base metal, and performs welding by inserting an additive wire into this molten pool, the arc current is set to two values at a predetermined period. A TIG welding method characterized in that the current is supplied at a low level and the low level is set to a small current value in a region where the welding voltage increases. (2) The cycle of the binary level arc current is 20Hz to 5
The TIG welding method according to claim 1, characterized in that the welding frequency is set to 00 Hz. (3) The TIG welding method according to claim 1, characterized in that the arc current at the low value level is 50 amperes or less.