JPS6340673A - Horizontal pulse arc welding method - Google Patents

Abstract

PURPOSE:To stabilize the formation of a penetration bend and to prevent the generation of a blow hole by using the shielding gas mixing a CO2 gas in spe cific amount to an argon and performing the pulse welding of the line to be welded of both side faces in the same direction with respective torch simultane ously. CONSTITUTION:The shielding gas mixing CO2 of about 30-60% to argon is used in case of performing a penetration welding from the horizontal direction of the line L to be welded of both side faces by abutting bisected materials 1, 2 to be welded from the upper and lower directions. The lines L1, L2 to be welded are then simultaneously welded with the torches T1, T2 for consumable electrode welding. The tip 3a of a consumable electrode 3 is crept to the inner part of the surface 1a, 2a of the material to be welded, the molten metal of the tip 3a on which periphery the wall of molten metals 1b, 2b exists is transferred by synchronizing with a pulse current and a droplet 4 is stably transferred. The tolerance of a gap is, therefore, large, no dropping is caused, the penetration bead is stably formed and the generation of a blowhole can be eliminated as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an arc welding method in which halves of materials to be welded are abutted from above and below, and welding lines on both sides are welded horizontally.

[Prior art]

2 and 3 are a front perspective view 3 and a side view showing the arrangement of a welding material and a welding torch for carrying out a conventional welding method of the present invention, 2 is a material to be welded by f-cutting, for example, an axle housing of an automobile axle, and the welding lines L1 and L2 or L3 and L4 on both sides are butted from above and below,
From the horizontal direction, welding torches r1 and T2 or r3 and r4 are used to perform back wave welding using the arc welding method.

The first conventional welding method for arc welding the materials to be welded shown in FIGS. 2 and 3 is a carbon dioxide arc welding method (hereinafter referred to as C02 welding).

In this method, the range of optimal welding conditions that can continuously form uniform Uranami beads is very narrow, so it is not possible to continuously obtain good Uranami beads. The reason is as follows. FIG. 4 is an enlarged view of the part indicated by the dotted line A in FIG. It is extremely difficult in practice to press punch and arrange so that each total length ≦ and each total length (approximately - constant S) of the lines to be welded of a large number of materials to be welded. , conventional C
In the O□ welding method, in areas where the gap G is large, the bead hangs down on the back side, as shown in Figure 4 (B), and in areas where the gap G is small, as shown in Figure 4 (B). (C
)1 As shown, no Uranami bead was formed, and in both cases, the bond strength was insufficient, resulting in defective products. In addition, FIG. 4(A) shows that the gap G is appropriate,
It is a figure showing that a good Uranami bead was obtained. Next, in order to reduce the variation in the gap G due to one thermal strain during welding, welding in one direction at the same time with four welding torches is shown in Figure 1. is desirable, but C
In 02 welding, the arc became unstable due to magnetic blowing, and stable welding results were sometimes not obtained.

In this way, in the conventional C02 welding method, the range of optimal welding conditions is narrow, resulting in a high number of defects, and manual [α
It required a lot of effort.

Therefore, as a second conventional welding method, a MAG pulse welding method using argon gas containing 20% carbon dioxide gas (1'lF, referred to as COt) has also been put into practical use. This MAG pulse welding method.

The tolerance of gap G is CO! Since it is larger than welding, a stable Uranami bead can be obtained, but as a result of X-ray testing, a large number of blow balls were generated in the weld, and JIS Z3104
The drawback was that only grades 2 to 4 could be obtained in the X-ray test.

[Problem that the invention seeks to solve]

In the first conventional method of arc welding the materials to be welded shown in Figure 2, CO! The welding method has the disadvantage that the tolerance of the gap G is small, causing sag and the inability to obtain an underwave bead.Also, the MAG pulse welding method, which is the second conventional method, causes blowholes. Therefore, the present invention has been developed to solve the problem that the materials to be welded shown in FIG. 1 and FIG. It is an object of the present invention to provide a welding method in which blowholes are formed and do not generate blowholes as in the conventional MAG welding method.

[Effect]

The present invention provides a conventional method of welding the liquid welding lines L1 to L4 on both sides from the horizontal direction by abutting halves of the welded materials 1.2 from above and below, as shown in FIG. Argon gas 30 to 60% CO2? Use a shield gas with a footrest.

Weld lines L1 and L2 on both sides. or L3 and L
1, or Ll to Ll simultaneously in the same direction, respectively, with consumable electrode welding torches T1 and T2. or Ta2 and r4
．． Or move 'r 1 to T4 and pulse 71!
This is a horizontal pulse arc welding method in which welding is carried out by

The reason for limiting the welding conditions of the welding method of the present invention will be explained below.

Figure 5 shows the mixing ratio of CO2 in argon gas (horizontal axis)
This is a diagram showing the relationship between the welding current (vertical axis) and the welding current (vertical axis) at which spray transfer occurs, where spray transfer occurs in chain acids above the upper curve SP, and i in the F direction than the lower curve DP.
In the in region, there is a drop transition, and the bright region between the two curves indicates a mixed range, and the C in the argon gas at point IOC
When the O2 mixing ratio reaches around 30%, even if the welding current value is increased.

It is known that spray transfer is impossible.

Therefore, in order to reduce the generation of spatter and perform stable arc welding, the spray S range has traditionally been used, and argon gas containing 5 to 20% CO2 has been used. There is.

On the other hand, it is known that the lower the mixing ratio of CO2, the more blowholes are likely to occur.
Argon gas mixed with 20% CO2 is said to be suitable for Nk.

Figure 6 shows the number of blowholes (vertical FIG. The welding conditions shown in FIG.

Material and plate thickness Soft M5m thickness Butt output Current Pulse sleep current 420A Base current 60
A Average value 280A Pulse frequency 250Hz Output voltage Average value 25V Welding speed
65cb In the same figure, curve B
As shown by H, blowholes no longer occur when the CO2 mixing ratio exceeds 40%, and conversely, blowholes occur when the CO2 mixing ratio is less than 40%, and the number of blowholes increases as the CO2 mixing ratio decreases. . The mixing ratio of C02 is 3
When it is 0%, the number of blowholes is 10/250t*
This corresponds to the first grade of the X-ray test method of JIS Z 3104, and is within the permissible range. Next, r of C02
When the foothold ratio exceeds 40%, blowholes will no longer occur, but the droplets will become large and move irregularly, making it impossible to form a smooth Uranami bead. For this reason, conventionally, mixed gases in which the mixing ratio of CO2 exceeds 30% have not been practically used.

Therefore, the present invention only allows the occurrence of blowholes with a C02 mixing ratio of 30% or more to be within the permissible range.

In order to achieve smooth droplet transfer, a high current of 250 to 350 A is used for horizontal welding of a soft plate with a thickness of 5 m+.1 For example, when the average current is 25 OA, the pulse average voltage is 2.
Lowering the voltage to about 5V: As a result, as shown in FIG. The format was adopted. When a pulse current is applied in this "hidden arc" form, the electrode tip 3a
The molten metal of the material to be welded is surrounded by the molten metal of @1b and 2b.
Because of the existence of this wall, the molten metal at the electrode tip 3a moves around the circle a1 in synchronization with the pulse current, and it was devised that the droplets 4 can be transferred stably in the same way as spray transfer. . In addition.

In FIG. 1, reference numeral 5 indicates an arc, and reference numeral 6 indicates arc light.

Based on the above idea, the material to be welded shown in Fig. 2 was
Pulse welding number 1 A pulse welding condition that allows better uranami welding to be obtained was investigated. Figure 7 shows a diameter of 1.2 fl.
average pulse current 280 A, average arc voltage 2 using mild steel consumable electrodes and argon gas containing 40% CO2.
Apply two pulsed currents of 5V.

Pulse energization time (hereinafter referred to as pulse width) TP (lateral Pl)
h) is a diagram illustrating an appropriate pulse current value 1p (vertical axis) that can destroy a good Uranami bead when changing .h). In the figure, the range m between curves PA and PB is the range in which a good underwave bead can be obtained. Next, when the mixing ratio of CO2 is increased under the proper pulse conditions determined in Fig. 7, the molten metal at the tip 3a of the consumable electrode becomes normal CO, As with welding, the grains become large and cause a short circuit with the molten metals 1b and 2b of the welded materials.

If the CO2 mixing ratio exceeds 60%, smooth droplet transfer corresponding to the pulse current will not occur, making it impossible to obtain stable Uranami beads. For the above reasons, the mixing ratio of CO2 in the welding method of the present invention is limited to 30 to 60%.

〔Example〕

From the above study and experimental results, we found that the workpiece shown in Fig. 2 is suitable for conventional CO2 welding and conventional MAG welding (
The welding method of the present invention was applied to the workpiece in comparison with the welding process using argon with a CO2 mixing ratio of 20%.
Mild steel plate thickness 5f1 25I! /min Consumable electrode Mild steel diameter 1.2fl Projection length
12-15fl Pulse average current 260-280A Welding average voltage 25-26V Welding speed 65σ/min The appearance photograph of the surface bead welded by the welding method.

In the photo 2 of the outer appearance of the back bead and the macro cross-sectional photo, spatter is observed in the photo of the front bead 1.

(The photo of the back bead shows some areas where dripping is occurring.) Despite this, a uniform immersion bead is not obtained, and even the cross-sectional macro photo shows the appearance of the front bead welded using the Uranami welding method. The photo shows the exterior photo and cross-sectional macro photo of the long bead, and both the long bead and the back bead are approximately average. , (A bead was obtained, and a good shear wave bead was obtained in the cross-sectional macro photograph, but when a separate X-ray test was performed, the point BH of the curve BH in Fig.
2f As shown in the figure, during the welding length 2501, each of the 40 beads was welded by the welding method of the present invention. Approximately uniform beads are obtained,
A good Uranami bead was obtained in the cross-sectional macro photograph, and in a separate X-ray test, the weld length 2
Only three blowholes were generated during 50 fH, which was sufficient (within the first grade range).

〔effect〕

According to the welding method of the present invention, when the materials to be welded shown in Fig. 2 are produced by normal press working and butted, the gap G is 0.5 tn However, there are disadvantages such as dripping and failure of the Uranami beads (also, conventional M
AG welding (argon gas with 20% CO2)
Good Uranami beads can be stably obtained with normal press cleanliness without producing many blowholes.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the state of the tip of the consumable electrode and the molten metal of the material to be welded when the welding method of the present invention is carried out. FIG. 2 is a front perspective view showing the arrangement of welding materials and welding torches used in the conventional welding method and the welding method 1 of the present invention. FIG. 3 is a side view of FIG. 2, and FIG. 4 is an enlarged view of dotted line A in FIG. Figure 5 shows CO in argon gas at the downward welding point 5.
, a diagram showing the relationship between the mixing ratio (horizontal axis) and the welding current (vertical axis) at which spray transfer is obtained. Figure 6 shows the mixing ratio of Co1 in argon gas (horizontal axis) and the number of blowholes (
A diagram showing the relationship with the vertical axis). FIG. 7 is a diagram showing the relationship between the pulse energization time TP (horizontal axis) and the pulse current value 1p (vertical axis) for obtaining a proper Uranami bead in the welded material shown in FIG. 2. 1.2... Material to be welded, Ll to L4... Line to be welded. -r 1 to 'r 4...Welding torch agent Patent attorney Hiroshi Nakai Figure 2 (L3) 7 (L Shrine Figure 2 (C) (B) (K) 5th
figure

Claims (1)

[Claims] In an arc welding method in which halves of the materials to be welded 1 and 2 are abutted from above and below and the weld lines L_1 and L_2 on both sides are welded horizontally, 30 to 60% of argon gas is added.
Using a shielding gas mixed with % carbon dioxide gas, weld the consumable electrode welding torch T in the same direction on both sides of the weld line at the same time.
A horizontal pulse arc welding method in which _1 and T_2 are moved and welded by pulsed current.