JPH0394978A - Crater treating method for arc welding - Google Patents

Abstract

PURPOSE:To prevent the generation of a crater at an end of a weld bead at the time of arc welding of Al by attenuating and changing a welding current and the welding wire feed rate with the lapse of time, stopping the wire feed and then, immediately raising the welding voltage in order to treat the crater. CONSTITUTION:When a primary crater treating stage of a crater treating period of time begins, the welding voltage supplied to a weld zone is decreased gradually according a first slope-down characteristic from a welding set level V1 at the stationary time up to a first crater set level V2. As a result, heat input of the weld zone is decreased gradually and simultaneously with this, the feed quantity of a welding wire is also decreased according to the welding voltage. When the primary crater treating stage is completed, the welding wire feed is then stopped in the state with the welding voltage of the first crater set level V2 maintained and the heat input applied to the weld zone. As a result, since welding conditions of the welding wire and the weld zone are changed gradually, the generation of the crater is suppressed remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to improving a crater treatment method suitable for arc-welding aluminum mounds.

[Prior Art] In arc welding of aluminum, as shown in Fig. 3, if the welding power source is shut off immediately upon completion of welding the base material a, and at the same time the feeding of the welding wire is stopped (the Figure 3 (a
), (b)), at the end of weld bead b, there is a third
It is well known that concave craters c1 as shown in Figure (C) occur. Therefore, in order to prevent the occurrence of such craters, the welding t
A method is adopted in which the welding source is instantly switched from the welding setting level ■1 in steady state to a lower level V2 and supplied for a certain period of time, and at this time, the feeding speed of the welding wire (not shown) is gradually reduced. (Fig. 4 (a), (b)
), this method reduces the size of crater C2, but as shown in No. 40ffi(c), another crater c2' is formed around crater C2 like a mountain, which makes the appearance of the crater C2 smaller. It was quite difficult to obtain good beads. Therefore, the applicant of the present application proposed an improved crater treatment method in Japanese Patent Application No. 62-264791. As shown in FIGS. 5(a) and 5(b), this crater treatment method changes the welding voltage from the steady state welding setting level V1 to a lower crater treatment level ■2 at the end of welding. It was designed to suppress the generation of craters as much as possible by gradually decreasing the amount of crater C3 over time, and as shown in Figure 5 (C), it is possible to make crater C3 smaller. When performing aluminum welding, there was a problem in particular that crater treatment marks remained and the exterior appearance was to be avoided.

[Problems to be Solved by the Invention] The present invention is proposed to solve the above-mentioned problems, and it suppresses the occurrence of craters at the end of the weld bead when arc welding aluminum, and improves the appearance. The object of the present invention is to provide a crater treatment method that can obtain a good weld beat.

[Means for Solving the Problems] The present invention proposed to achieve the above object has been made through intensive study by the inventor, and is based on the welding voltage and the voltage applied to the welded part for crater treatment. By attenuating and changing the welding wire feeding speed over time and immediately increasing the welding voltage after stopping the welding wire feeding, a well-formed bead with a well-shaped crater area can be obtained. This was achieved by learning the facts.

In the method of the present invention, during the crater treatment period when aluminum is arc welded, in the first crater treatment step, the welding voltage supplied to the welded part is adjusted from a predetermined welding level to a steady state welding level. A first slope-down characteristic is provided that gradually decreases over time until a first crater setting level is reached, and the feeding speed of the welding wire is decreased in accordance with changes in the welding voltage, and then the processing step When the welding wire is finished, the feeding of the welding wire is stopped, and this
1! The second step carried out following the first crater treatment step
In the next crater treatment step, the welding voltage supplied to the part to be welded is increased to a second crater setting level higher than the first crater setting level for a predetermined period of time, and then this second crater setting level is
From the crater setting level to the time when the welding power source is cut off, the supply level is given a second slope-down characteristic in which the supply level gradually decreases over time. [Function] In the crater treatment method of the present invention, when entering the first crater treatment step of the crater treatment period, the welding voltage supplied to the welded part is increased from the steady welding setting level to the first crater setting level. Since the welding voltage is gradually decreased according to the slope-down characteristic of the welding voltage, the heat input to the welded part is gradually decreased, and at the same time, the welding wire feeding amount is also decreased according to the welding voltage (heat input). Then, at the end of the first crater treatment step, the welding voltage is maintained at the first crater setting level and the feeding of the welding wire is stopped while heat is being applied to the 'III' weld zone. As a result, the melting conditions of the welding wire and the welded part gradually change, so the generation of craters is significantly suppressed.

When the second crater treatment process starts following this first crater treatment process, the welding voltage supplied to the part to be welded is immediately increased from the crater setting level of @1 to the crater setting level of 1K2 for a predetermined period of time, and then , again gradually decrease and cut off.

As a result, the crater surface is melted and shaped by the heat input, resulting in a bead with a good appearance.

[Example] The method of the present invention will be explained below with reference to the accompanying drawings.

In the crater treatment according to the present invention, as shown in FIG. 1(a), the welding voltage at the start of the first crater treatment process starts from the steady state welding voltage level ■I, and the first slope down time T1 In between, the first crater setting level V
2, and then the first crater is set and the bell v2 is maintained until time T2 has elapsed.
On the other hand, the feeding speed of the welding wire is changed in the same way as the welding voltage, and the feeding is stopped when time T2 has elapsed and the first processing step is completed, and the voltage level in each processing step is adjusted. is V2<V3<Vl.

In the second crater treatment step that follows this first crater treatment step, the welding voltage is set to the first crater setting level v.
2 to the second crater setting level V3 for a predetermined time, and after time T3 has elapsed, the welding voltage is increased to the second crater setting level V3 during the second slope down time T4.
The voltage is changed again in an attenuating manner from to zero level and is shut off.

Here, the welding wire is usually connected to a torch switch (not shown)
The first operation starts feeding the welding wire toward the base metal, and after the welding wire comes into contact with the base metal, the welding wire continues to be fed even if the operation of the torch switch is released. Welding progresses in this state, and by starting the operation of the torch switch a second time, it is switched to crater treatment at the end of welding, and the time T2 of the first crater treatment step can be changed depending on the operation time. The secondary crater treatment step is automatically performed according to predetermined data.

Here, welding setting level V1, first slope down time T1, first crater setting level ■2, second crater processing time (T3+74), second crater stage setting level V3, and second slope down time The jump T4 is set to the maximum value in advance depending on the contact conditions such as the material and thickness of the welding base material a. i value, and the feeding speed of the welding wire is also set to a characteristic according to the welding conditions.

For example, depending on the setting of T1, changes in welding voltage and welding wire feeding speed may exhibit characteristics as shown by the dashed-dotted lines in FIGS. 1(a) and 1(b).

In such a method of the present invention, the amount of particles supplied to the end of the weld bead b in the first crater treatment step gradually decreases, and the amount of welding wire fed decreases accordingly. In addition to suppressing the formation of craters as in the treatment of Figure (C
), it is possible to obtain a weld bead that is significantly smaller and has a smart build-up.

FIG. 2 shows a schematic configuration 1'2 of an apparatus for carrying out the method of the present invention.
It shows I. As shown in the figure, the main parts of the device include a first crater level setting device 1, a first slope down time setting device 2, and a second slope down time setting device 2.
crater level setting device 3, second slope down time setting device 4, second crater processing time setting device 5l, signal processing circuit 6, welding voltage control circuit 5'87, steady welding level setting device 8 and welding wire feed It is constructed by combining circuits 9.

To explain the basic operation, when welding is started by operating a torch switch (not shown), during steady welding, the signal processing circuit 6 sets the control i3j according to the data set by the steady welding level setting device 8. Welding progresses by sending a signal to the melt 1a voltage control circuit 7 and the welding wire feed circuit 9.

At the end of welding, the operation of the torch switch is started and the first
When entering the next crater treatment process, the data set by the first crater level setting device 1 and the first slope down time setting device 2 are processed by the signal processing circuit 6, and the welding voltage control circuit 7 and the welding wire feed are processed. A control signal is sent to the feed circuit 9, and the welding voltage control circuit 7 controls the welding voltage to a set condition by driving an output control element (not shown), and the welding wire feed circuit 9 controls the welding voltage to a set condition. The welding wire is fed at the specified speed. Then, when the operation of the torch switch is released, the feeding of the welding wire is stopped and the second crater treatment process begins.

In the second crater processing step, the signal processing circuit 6 processes the data set by the second crater level setting device 3, the second slope down time setting device 4, and the second crater processing time setting device 5. Then, a control signal is sent to the welding voltage control circuit 7, and the welding +! In the voltage control circuit 7, the method of the present invention is implemented by driving the output control element to control the welding voltage to a set condition. In the above description, the case where arc welding is performed is explained, but the method of the present invention is not limited to this case, and the method of the present invention can also be applied to pulse welding. [Effects of the Invention] According to the method of the present invention, the heat input to the welded part during cratering treatment gradually changes in an attenuated manner, and at the same time, the amount of image sent by the welding wire decreases with the passage of time. I'm going, so i +
The generation of craters at the end of the bead is significantly suppressed, and human heat is applied to shape the crater again after the feeding of the welding wire is stopped, resulting in a welded bead with a smooth and good appearance. is obtained.

[Brief explanation of drawings]

FIGS. 1(a) to 1(c) are explanatory diagrams of the crater treatment method in the method of the present invention; FIG. 1(a) is an explanatory diagram showing changes in the welding voltage supplied to the welded part; The figure is an explanatory diagram showing changes in the feeding speed of welding wire, (c) is a schematic explanatory diagram of a welding beat when the method of the present invention is implemented,
The figures are schematic configuration diagrams of an apparatus for implementing the method of the present invention, Figures 3 (a) to (c), Figures 4 (a) to (C), and Figure 5 (a).
-(C) are explanatory diagrams of the conventional crater treatment method, which are shown in imitation of FIGS. 1(a)-(C). [Explanation of code v1... Welding level in steady state ■2... First crater setting level ■3... Second crater setting level

Claims (1)

[Claims] (1) Prior to cutting off the welding power source at the end of welding,
In a crater treatment method in arc welding in which a welding voltage lower than the level supplied during steady welding is applied to the part to be welded, the period of crater treatment is divided into a primary crater treatment process and a secondary crater treatment process. However, in the first crater treatment step, the welding voltage supplied to the welded part is adjusted to a predetermined first slope from the steady welding level to the predetermined first crater setting level. The feeding speed of the welding wire is gradually decreased according to the down characteristics, and the feeding speed of the welding wire is decreased according to the change in the welding voltage, and finally, the feeding speed of the welding wire is stopped, and following the first crater treatment step, In the secondary crater treatment step to be performed, the welding voltage supplied to the welded part is increased from the first crater setting level to a higher second crater setting level for a predetermined period of time, and then A crater treatment method in arc welding, characterized in that the crater is gradually reduced according to a predetermined second slope-down characteristic, and finally a welding power source is cut off.