JPS60210368A - Three o'clock welding method - Google Patents

Abstract

PURPOSE:To form a defectless weld bead and to perform satisfactorily three o'clock welding by specifying the angle of a wire with the groove face on the lower side of a groove and the distance between the aiming position of the top end of the wire and the lower groove face. CONSTITUTION:A three o'clock narrow groove 8 is subjected to three o'clock welding in two upper and lower passes by a gas shielded arc welding method by which welding current is periodically and alternately changed high and low. The wire 14 to be fed in a welding torch 13 is held at >=5 deg. angle with the lower groove face of the groove 8. The wire 14 is also held at 1-3mm. distance between the aiming position of the top end thereof and the lower groove face. The satisfactory weld bead having no defect such as lack of fusion is formed by the stable arc according to the above-mentioned method and the easy and satisfactory three o'clock welding is made possible even with the narrow groove formed of thick plates.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a horizontal welding and welding method for welding a horizontal narrow gap.

[Prior art]

In general, as a method for welding a horizontal narrow gap, two plates to be welded (
1) and (2) are butted together to form a narrow groove (3) or (4) having an appropriate groove angle in a rectangular or v-shape, and the electrode wire is fed through the welding groove 1. There is a method of stacking welding heat (5) on the groove (3) or (4) by moving the torch linearly without weaving while holding the torch downward at a predetermined aiming angle, or as shown in Fig. 3. As shown, the aiming angle of the wire is 0° in the ■-shaped narrow groove (8) formed by the two plates to be welded (fe) and f7), that is, the groove surface of the groove (8). A method has been disclosed and practiced in which the welding heat (9) is laminated in each layer in parallel with the wire and the wire in each layer.

In addition, in FIGS. 1 to 3, fulli,
(Ili is each backing material.

By the way, in the former case, that is, when welding the grooves f3t and in shown in Figs. Conventionally, welding methods such as manual welding, submerged arc welding, and gas shielded arc welding have been widely put into practical use because of their ease of use; however, as the plate thickness increases, As the root spacing increases, the rate of increase in the cross-sectional area of the grooves +31, +4 is much larger than that of the ■-shaped groove (8) shown in Fig. 3; The cross-sectional area increases further, the amount of molten metal increases significantly, and the welding process takes a long time, making it unsuitable for horizontal welding of thick plates.

On the other hand, in the latter case, that is, when welding the groove (8) shown in FIG. Since the amount of molten metal does not increase, the amount of molten metal is small, making it suitable for horizontal welding of thick plates, even if the groove width is too large.

If it is too small, defects such as poor fusion will occur in the bead (9), so v! ] Destination (8)
The permissible range of the groove width that can be welded is normally limited to a narrow range of 8 to llam, which is a disadvantage in that it lacks practicality.

Therefore, as a method to eliminate the above-mentioned drawbacks, it is possible to weave the weld 1--ch in the vertical direction, which is the width direction of the groove, as is done in the case of normal downward welding, or to periodically increase the welding current. With alternating low
A welding method has been proposed in which the weld 1--ch is weaved in the vertical direction, which is the width direction of the groove, in accordance with changes in the welding current, but the former method does not produce the effect of weaving when welding downward. First, the latter method has the disadvantage that the mechanism and its control are very complex.

Then, as a method to eliminate all of these drawbacks, welded P1 and B in the same groove (8) as shown in Fig. 4 in the same groove (8) as shown in Fig. 3 in two passes, respectively. Conventionally, methods have been considered to do this.

At this time, since there is a risk that the molten metal (12) in the groove (8) may drip as shown in Figure 5, a cass shielded arc welding method is used in which the welding current is alternately changed from high to low in relatively long cycles. The lower heat (12j) of each layer is formed prior to the upper heat (I2) of each layer by a low frequency pulse MAG welding method with a certain frequency of about 05 to 1 Hz.

However, in this case, in order to melt the engraving on the lower beat (12), as shown in Fig. 7, welding I.
- Ti (1: (The wire (14) fed inside the bevel (
8) When held parallel to the groove surface, the distance d from the lower groove surface to the target position of the tip of Wi-j-11=Ij should be made small, and the distance d should be made appropriately small. By doing so, it is possible to sufficiently increase the amount of welding in the groove I/portion (R) and prevent the occurrence of poor fusion.

However, if the distance d is made too small, the wire (14
) and the bottom of the groove at the left end of the groove (8), but an arc occurs between the wire (14) and the lower groove surface, making the arc unstable and preventing good heat ( 12) and in order to obtain a stable arc, for example, if the diameter of the wire (14) is 1.2.11, the distance d
It is necessary to maintain the above distance [1...] or more.
If becomes too large, the arc will not reach the groove root portion (1<), and defects such as poor fusion will occur at the groove root portion (■<).

That is, the diameter of the wire (14) is set to 1.2. , the binding distance d was maintained at about 2 11j1, which is the minimum value that can obtain a stable arc, and the welding current was 280 to 360 A, the welding voltage was 28 to 32 V, and the high current welding conditions were as follows:
Welding time was 0.5 to IO seconds, welding current was 80 to 100 A, and welding voltage was 16 to 18 V as low current welding conditions.
As a result of experimentally welding the groove (8) by varying the flow time within the range of 0.5 to 10 seconds and in addition, varying the welding speed within the range of 10 to 40 cm/min, we found that both conditions However, poor fusion occurred in the groove loops 1 to 1 (I).
As long as the twist (I.11) and the groove surface of the groove (8) are parallel, there is a problem in that even if the arc is stabilized, the occurrence of fusion failure cannot be prevented.

[Purpose of the invention]

This invention was made with the above points in mind,
The purpose is to form a good welding joint free of defects such as poor fusion.

[Structure of the invention]

This invention increases the welding heat of each layer in the lateral direction of a narrow lateral gap by using a cass shielded arc welding method in which the welding current is periodically varied between high and low.

In the horizontal welding method in which the lower bead is formed in two passes, when forming the beat on the lower side of each layer, the wire fed through the welding 1-ch is applied to the groove surface on the lower side of the narrow groove. This horizontal welding method is characterized in that the angle is maintained at 5 degrees or more, and the aimed position of the tip of the wire is maintained at 1 to 3 degrees from the lower groove surface.

〔Effect of the invention〕

Therefore, according to the horizontal welding method of the present invention, the angle of the wire with respect to the lower groove surface of the narrow groove is maintained at 5 degrees or more, and the aimed position of the tip of the wire is 1° from the lower groove surface. By keeping the welding temperature at ~3 runs, it is possible to form a good welding heat with a stable arc without defects such as poor fusion, and even in a narrow gap formed by a thick plate, it is possible to easily and This makes it possible to perform horizontal welding well and is very practical.

〔Example〕

Next, this invention will be explained in detail with reference to FIG. 8 showing the actual results of one embodiment thereof.

Now, the same ■-shaped groove (8) as in Fig. 4 is welded at a frequency of 0.5, which is a cast-n-rule welding method in which the welding current is periodically changed high and low alternately as in the case of Fig. 4. ~IH
When welding by low frequency pulse IVI A G welding method of about Z, a wire (14) with a diameter of 12 mm is used, the welding speed is 18 cmZ, and the welding current is 35OA
.

High current welding conditions include a welding voltage of 32cm, a conduction time of 0.7 seconds, a welding current of 100cm, and a welding voltage of 18cm.

Under low current welding conditions with a flow time of 0.7 seconds, the angle θ of the wire (14) with respect to the lower groove surface of the groove (8), the aim position of the tip of the wire (141), and the above-mentioned As a result of experimentally forming only the lower weld bead of each layer in the groove (8) by changing the distance m# and d from the lower groove surface, it was found that poor fusion occurred in a part of the groove 1. The presence or absence is shown in Figure 8.

That is, in FIG. 8, the mark indicates a case where no fusion failure occurs, and the square mark indicates a case where a fusion failure occurs, and the angle θ is 06, that is, the groove surface of the wire (14) and the groove (8) When they are parallel, defective fusion will occur no matter how you change the distance (1).If the angle θ is set to 5 degrees or more and the distance d is in the range of 1 to 311I+, defective fusion will not occur and the result will be good. The allowable range of the groove width that allows for even better welding to be formed is 11 to 17.

By the way, if the angle θ is less than 10 degrees, the distance 1flI
If d is too small, the arc becomes unstable, and if the distance d exceeds 3, regardless of the angle θ, the arc will not reach the groove root, resulting in poor fusion.

Therefore, according to the above embodiment, since the angle θ was kept at 5 degrees or more and the distance III d was kept at 1-3 mm, a stable arc formed a good welding heat without defects such as poor fusion. The amount of molten metal does not increase, and the allowable range of groove width is reduced from 8 to 11
- from 11 to 17. , which makes it possible to easily and effectively perform horizontal welding even in a narrow gap formed by a thick plate, making it very practical.

In addition, in order to create a predetermined angle between the wire (14) and the lower groove surface of the groove (8), 1.-chi (13)
The entire structure may be tilted by the predetermined angle together with the wire (14), or only the wire (14) may be tilted by the predetermined angle by plastic deformation.

[Brief explanation of the drawing]

Figures 1 to 4 are cutaway front views of the vicinity of the narrow gap welded by the conventional horizontal welding method, Figures 5 to 7 are cutaway front views for explaining the operation of Figure 4, and Figure 8. shows the experimental results in one embodiment of the horizontal welding method of the present invention, and is a diagram of the relationship between angle θ and distance (1). (8) Narrow gap, 1st stitch 1 Weld 1.
wire. Agent Patent Attorney Fujita 111 Abe Fig. 1 Fig. 21 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Yesterday 1 No. 7, 11 18 Fig. 4 1111fLθ(@)-

Claims (1)

[Claims] ■ Gas-shielded arc welding, in which the welding current is periodically varied between high and low, is used to weld each layer in the horizontal direction of a narrow horizontal gap in two passes, top and bottom. , when forming the heat on the lower side of each layer, the angle of the wire fed through the welding torch with respect to the groove surface on the lower side of the narrow groove is maintained at 5° or more, and the tip of the wire is The aim position is 1 to 1 from the lower groove surface.
A horizontal welding method characterized by holding in three positions.